JPS62257415A - Molded article of molecule orientated and silane crosslinked ultra-high-molecular-weight polyethylene and production thereof - Google Patents

Abstract

PURPOSE:To obtain a molecule orientated molded article having improved heat resistance, by thermally molding a composition containing ultra-high- molecular-weight polyethylene, silane compound, etc., drawing, impregnating the molded article with a silanol condensation catalyst, bringing the impregnated molded article into contact with water and crosslinking. CONSTITUTION:A composition comprising an ultra-high-molecular-weight polyethylene having >=5dl/g intrinsic viscosity in decalin solvent at 135 deg.C, silane compound, radical initiator and diluent is thermally molded to give a molded article of an ultra-high-molecular-weight polyethylene onto which the silane compound is grafted. Then the molded article is drawn. The molded article is brought into contact with a silanol condensation catalyst during or after drawing. Consequently, the molded article of a molecule orientated and silane crosslinked ultra-high-molecular-weight polyethylene is obtained. The polyethylene shows two or more crystal melt peaks at temperature 10 deg.C higher than the original crystal melt temperature (Tm).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a molecularly oriented and silane-crosslinked ultra-high molecular weight polyethylene molded article and a method for producing the same, and more particularly relates to a stretched molded article of ultra-high molecular weight 4-lyethylene. The present invention relates to a molded product having a high modulus of elasticity and high tensile strength characteristic of , as well as significantly improved heat resistance and adhesiveness, and a method for producing the same.

(Prior art) It is already known that ultra-high molecular weight polyethylene can be formed into fibers, tapes, etc. and stretched to produce molecularly oriented molded products having high elastic modulus and high tensile strength. JP-A-56-15408 describes spinning a dilute solution of ultra-high molecular weight polyethylene and drawing the resulting filament. Also, JP-A-59-1
In Publication No. 30313, Superpolymer 1? It is described that melt-kneading polyethylene and wax, extruding the mixed wire, cooling and solidifying, and then stretching, and furthermore, JP-A-59-18761
Publication No. 4 describes that the above-mentioned molten mixture is extruded, drafted, cooled and solidified, and then stretched.

On the other hand, it is already known that silane crosslinking is carried out for the purpose of imparting heat resistance etc. to polyolefin. It is described that after grafting, crosslinking is carried out by exposing to moisture in the presence of a silanol condensation catalyst. Also, JP-A-54-111
No. 54 describes that a silane-grafted polyolefin molded product is immersed in a mixed solution of a silanol condensation catalyst and a solvent to speed up the crosslinking process, and furthermore, JP-A No. 52-
Japanese Patent No. 154872 describes that an oriented product of silane grafted polyolefin is subjected to extraction treatment after crosslinking.

(Problems to be Solved by the Invention) However, a stretched product of ultra-high molecular weight polyethylene,
For example, fibers, tapes, etc. have high elasticity, high tensile strength,
Although it is lightweight and has excellent water resistance and weather resistance, it has one of the drawbacks inherent to polyethylene: poor heat resistance and poor adhesiveness.

Further, with conventional polyethylene silane crosslinking technology, a stretched molded product with high elastic modulus and high tensile strength cannot be obtained, and the effect of improving heat resistance is also insufficient.

It is generally known that the heat resistance of polyolefins is improved by molecular orientation of polyethylene or by crosslinking of polyethylene, but there are limits to the improvement of heat resistance in this conventional technology. The melting point of polyethylene is in the relatively low range of 110 to 140°C, and as far as the present inventors know, it is impossible to avoid the restriction that the melting point of polyethylene is in a relatively low range of 110 to 140°C. After exposure, most things melt,
Its strength is lost.

Therefore, an object of the present invention is to provide a molecularly oriented molded article of ultra-high molecular weight polyethylene which has significantly improved heat resistance, adhesion and creep resistance.

Another object of the present invention is to maintain the shape of the stretched molded product without melting even when exposed to a temperature of 180°C for 10 minutes, and to maintain a high strength retention rate even after the above-mentioned thermal history. Molecular orientation and silane cross-linked ultra-high molecular weight, i? An object of the present invention is to provide an IJ ethylene molded product.

Still another object of the present invention is to provide a silane-crosslinked ultra-high molecular weight polyethylene molded article having a combination of heat resistance, adhesiveness and creep resistance suitable for use as strength fibers in resin composites, and a method for producing the same. be.

(Means for Solving the Problem) The present inventors grafted a silane compound to ultra-high molecular weight XZV ethylene having an intrinsic viscosity [η] of 5 dt/i or more in the presence of a radical initiator, and then extruded it. Then, when the extrudate is impregnated with a silanol condensation catalyst after stretching or during stretching and then exposed to moisture and crosslinked, a phenomenon of improvement in the melting temperature that is not observed at all in conventional polyethylene stretched and crosslinked products occurs. It is possible to obtain a novel molecularly oriented molded product in which 18
10 minutes at a temperature of 0°C! It has been found that the shape of the stretched molded product is maintained without melting even when exposed to heat, and that a high strength retention rate is maintained even after this heat history. Furthermore, it has been found that in this stretched molded product, the high elastic modulus and high tensile strength characteristic of ultra-high molecular weight polyethylene stretched molded products are maintained, and the adhesion and creep resistance are also significantly improved.

That is, according to the present invention, there is provided a molded article of molecularly oriented and silane-crosslinked ultra-high molecular weight polyethylene, which has a main melting point during the second temperature rise when measured with a differential scanning calorimeter in a restrained state. The original crystal melting temperature of ultra-high molecular weight polyethylene is required as a peak! (Tm) at least 10
At least two crystal melting peaks (Tp
), the heat of fusion based on this crystal melting peak (Tp ) per total heat of fusion is 40% or more, and the strength retention rate after giving a thermal history of 10 minutes at 180 ° C. is 60%. A molded article characterized by the above is provided.

According to the present invention, a composition containing ultra-high molecular weight ethylene having an intrinsic viscosity [η] of 5 dl11 or more, a silane compound, a radical initiator, and a diluent is thermoformed, and ultra-high molecular weight polyethylene grafted with a silane compound is produced. A molecular orientation and silica method characterized by stretching a molded product, impregnating a silanol condensation catalyst into the stretched molded product during or after stretching, and then crosslinking the stretched molded product by bringing it into contact with moisture. /Cross-linked superpolymer site? A method for producing a polyethylene molded body is provided.

(Function) The present invention provides that when ultra-high molecular weight polyethylene grafted with silanes is molded, this molded product is stretched, and then silane crosslinking is performed, at least a portion of the polymer constituting the stretched and crosslinked molded product is formed. This is based on the surprising finding that the melting point of the chains increases under restraint conditions.

The melting point of a polymer is associated with the melting of crystals in the polymer, and is generally measured as the endothermic peak temperature associated with crystal melting using a differential scanning calorimeter. This endothermic peak temperature is
Once the type of polymer is determined, it remains constant, and it hardly changes due to subsequent treatments, such as stretching treatment or crosslinking treatment.Even if it does change, it is well known that the most variable case is stretching heat treatment. However, it will only move to the higher temperature side by about 15 degrees Celsius at most.

Figures 1 to 4 of the attached drawings show raw ultra-high molecular weight polyethylene (Figure 1) and drawn filaments of the polyethylene (Figure 2).
), undrawn filaments obtained by crosslinking the polyethylene with silane (Fig. 3), and filaments obtained by drawing the silane-grafted ultra-high molecular weight polyethylene and then crosslinking according to the present invention (Fig. 4) under restraint conditions. The endothermic curve measured using a differential scanning calorimeter is shown. For details of the processing conditions, please refer to the example described later.

These results show that simply drawn or silane-crosslinked ultra-high molecular weight polyethylene exhibits an endothermic peak associated with crystal melting at approximately 135°C, which is almost the same as untreated ultra-high molecular weight polyethylene; The peak area (heat of fusion) is smaller than that of the untreated product, whereas the stretch-crosslinked molded product according to the present invention has a peak area (heat of fusion) at the melting peak temperature of the untreated ultra-high molecular weight polyethylene. It can be seen that although small peaks remain, the large peaks have rather shifted to the high temperature side.

FIG. 5 shows an endothermic curve when the sample shown in FIG. 4 was subjected to a second run (second temperature raising measurement after the measurement shown in FIG. 4 was performed). The results shown in Figure 5 indicate that in the case of re-heating, the main peak of crystal melting is at almost the same temperature as the melting peak temperature of untreated ultra-high molecular weight polyethylene; Since the orientation has almost disappeared,
The shift of the endothermic peak to the high temperature side in the sample in Figure 4 is as follows:
This shows that it is closely related to the molecular orientation in the molded body.

In the present invention, the fact that the crystal melting temperature of at least some of the polymer chains constituting the molded article shifts to a higher temperature side due to the drawing of the ultra-high molecular weight teriethylene and the silane crosslinking increases the crystal melting temperature. This was a truly unexpected and novel discovery, as the means to do so were previously unknown.

Although the reason why the crystal melting temperature shifts to a higher temperature side in the oriented crosslinked molded article of the present invention has not yet been fully elucidated, the present inventors estimate this reason as follows. That is, when the silane-grafted ultra-high molecular weight teriethylene is subjected to a stretching operation, the silane-grafted portion selectively becomes an amorphous portion, and an oriented crystal portion is generated through this amorphous portion. Next, when this stretched molded body is crosslinked in the presence of a silanol condensation catalyst, a crosslinked structure is selectively formed in the amorphous portion, resulting in a structure in which both ends of the oriented crystalline portion are fixed by silane crosslinking. In a normal stretched molded product, crystal melting proceeds from the amorphous portions at both ends of the oriented crystal part, whereas in the stretched and crosslinked molded product of the present invention, the amorphous parts at both ends of the oriented crystal part are selectively crosslinked, It is recognized that because the polymer chains are less likely to move, the melting temperature of the oriented crystal portion is improved. This structure can be further characterized as follows by observation using a differential scanning calorimeter. Figure 6 shows the crystallization measured using the temperature-lowering process to move from the measurement at the elevated temperature shown in Figure 4 to the measurement at the elevated temperature shown in Figure 5, i.e., the second temperature. Shows the heat generation curve at From this, a shoulder or broad sub-peak is observed on the high temperature side of the main exothermic peak. Also, in the second run during the second temperature increase (FIG. 5), a shoulder is observed on the high temperature side of the Tm peak.

Normally, in polyethylene, a single sharp exothermic peak is observed during the cooling process from a molten state, and no shoulder or peak is observed on the high temperature side of this peak.

Further, even in the case of ordinary crosslinked polyethylene, although the peak may be broad, no shoulder or peak is observed on the high temperature side. Even in the second run, an endothermic peak on the high temperature side of Tm is not observed in both normal polyethylene and crosslinked polyethylene. It is believed that this thermal behavior is a trace of the new oriented crosslinked structure and is related to the excellent heat resistance properties, Cree-7° resistance, etc. Thus, in the present invention, the molded product not only maintains its shape stably even at a high temperature such as 160°C, but also achieves a high strength retention rate even after this thermal history.

(Description of Preferred Embodiments of the Invention) In order to facilitate understanding, the invention will be described in detail below in the order of raw materials, processing means, and objects.

Raw material The ultra-high molecular weight polyethylene (A) used in the method of the present invention is a decalin solvent with an intrinsic viscosity [η] of 5 at 135°C.
dlli or more, preferably in the range of 7 to 30 dlli. If [η] is less than 5 dt/i, a stretched product with excellent tensile strength cannot be obtained even if the stretching ratio is increased. Also, there is no particular restriction on the upper limit of [η], but 30
Those exceeding dl/1/ have an extremely high melt viscosity at a high kneading level, tend to cause melt fractures during extrusion, and have poor melt spinnability. Such ultra-high molecular weight polyethylene refers to ethylene or ethylene and small amounts of other α-olefins such as propylene, 1-pudene, 4-methyl-
Among polyethylenes obtained by polymerizing 1-pentene, 1-hexene, etc. by so-called Ziegler polymerization, it has a much higher molecular weight.

On the other hand, the silane and compound used for grafting treatment may be any silane compound as long as it is capable of grafting treatment and crosslinking treatment, and such silane compounds can be hydrolyzed with radically polymerizable organic groups. It has both an organic group and the following general formula % formula % (1), where R is an organic group containing radically polymerizable ethylenic unsaturation, and Y is a hydrolyzable organic group. Aυ, n is a number of 1 or 2 and is expressed as ruru.

Examples of radically polymerizable organic groups include vinyl group, allyl group,
Examples include ethylenically unsaturated hydrocarbon groups such as butenyl and cyclohexenyl groups, and alkyl groups containing ethylenically unsaturated carboxylic acid ester units such as acryloxyalkyl and methacryloxyalkyl groups. groups are preferred. Examples of hydrolyzable organic groups include alkoxy groups and acyloxy groups.

Suitable examples of silane compounds include, but are not limited to, vinyltriethoxysilane, vinyltrimethoxysilane,
Vinyltris(methoxyethoxy)silane and the like.

Grafting and Molding According to the present invention, silane grafting and molding are performed by thermoforming a composition containing the ultra-high molecular weight polyethylene, a silane compound, a radical initiator, and a diluent by melt extrusion or the like. That is, due to the action of the radical initiator and the heat during melt-kneading, polymer radicals are generated in the ultra-high molecular weight polyethylene, and the reaction between the polymer radicals and the silane compound causes grafting of the silane compound to the ultra-high molecular weight polyethylene.

As radical initiators it is possible to use all the radical initiators used in this type of grafting, for example organic peroxides, organic bersesters such as benzoyl peroxide, dichlorobenzoyl oxide, dicumyl peroxide, di-tert- Butylyloxy p
, 2,5-zo(yloxyrbenzoate)hexyl-
3,1,4-ni'su(t+ert-butylyloxyisopropyl)benzene, lauroyl peroxide, te
rt-butylberacetate, 2.5-tmethyl-2,
5-di(tert-butylperoxy)hexyne-3,
2,5-dimethyl-2,5-di(tart-butylperoxy)hexane, tert-butylberbenzony), tart-butylberphenylacetate),
tart-butylberisobutyrate, tert-butylberisobutyrate, tert-butylberyl bivalate, cumylyl pivalate and tert-butylberdiethyl acetate, other azo compounds such as azobisisobutyronitrile, There is dimethyl azoisobutyrate. In order to effectively carry out grafting under melt-blended PJ moxibustion conditions of ultra-high molecular weight polyethylene, it is desirable that the half-life temperature of the radical initiator is in the range of 100 to 200°C.

In the present invention, a diluent is blended with the above components to enable melt molding of the silane-grafted ultra-high molecular weight polyethylene. As such a diluent, a solvent for ultra-high molecular weight polyethylene and various wax-like substances having compatibility with ultra-high molecular weight polyethylene are used.

The solvent preferably has a boiling point higher than the melting point of the polyethylene, more preferably higher than the melting point +20°C.

Specific examples of such solvents include n-nonane, n-decane, n-undecane, n-dodecane, n-tetradecane, n-octadecane, liquid paraffin, aliphatic hydrocarbon solvents such as kerosene, xylene, and naphthalene. , aromatic hydrocarbon solvents such as tetralin, butylbenzene, p-cymene, cyclohexylbenzene, diethylbenzene, pentylbenzene, dodecylbenzene, bicyclohexyl, decalin, methylnaphthalene, ethylnaphthalene, or hydrogenated derivatives thereof, 1,1,2 .2-Tetrachloroethane, pentachloroethane, hexachloroethane, 1,2.3-) Lichloroglonomon, dichlorobenzene, 11214-) IJ Halogenated hydrocarbon solvents such as chlorobenzene and chromobenzene, paraffinic process oil, naphthenic process Examples include mineral oils such as oil and aromatic process oil.

As the waxes, aliphatic hydrocarbon compounds or derivatives thereof are used.

The aliphatic hydrocarbon compounds are mainly saturated aliphatic hydrocarbon compounds, and usually have a molecular weight of 2000 or less,
The wax is preferably 1000 or less, more preferably 800 or less, which is called a rough-in wax. These aliphatic hydrocarbon compounds include tocosan,
n-alkanes with 22 or more carbon atoms such as tricosane, tetracosane, triacontane, or mixtures of these with lower n-alkanes as main components, so-called paraffin wax separated and purified from petroleum, ethylene or ethylene and other α-olefins Polyethylene such as medium/low pressure polyethylene wax, high pressure polyethylene wax, ethylene copolymer wax, medium/low pressure polyethylene, high pressure polyethylene, etc., which are low molecular weight polymers obtained by copolymerizing with Examples include waxes with reduced molecular weights, oxides of these waxes, oxidized waxes modified with maleic acid, and waxes modified with maleic acid.

Examples of aliphatic hydrocarbon compound derivatives include one or more, preferably one or two, particularly preferably one, carboxyl group or hydroxyl group at the terminal or inside of an aliphatic hydrocarbon group (alkyl group, alkenyl group). , fatty acids and aliphatic alcohols having 8 or more carbon atoms, preferably 12 to 50 carbon atoms, or molecular weights 130 to 2,000, preferably 200 to 800, which are compounds having functional groups such as carbamoyl groups, ester groups, meltcapto groups, and cargenyl groups. , fatty acid amides, fatty acid esters, aliphatic mercaptans, aliphatic aldehydes, aliphatic ketones, and the like.

Specifically, the fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid; the fatty alcohols include lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol; and the fatty acid amides include caprinamide, laurinamide, Examples of lumitinamide, stearylamide, and fatty acid ester include stearyl acetate.

In the present invention, the silane compound is contained in the range of 0.1 to 10 parts by weight, particularly 0.1 to 10 parts by weight, per 100 parts by weight of the ultra-high molecular weight polyethylene.
．． 2 to 5.0 parts by weight, the radical initiator in a catalytic amount, generally 0.01 to 3.0 parts by weight, especially 0.05 to 0.5 parts by weight.
Parts by weight and diluent range from 9900 to 33 parts by weight, especially 19
It is preferable to use the silane compound in an amount of 00 to 100 parts by weight.If the amount of the silane compound is lower than the above range, the crosslink density of the final stretched and crosslinked molded product will be too low and the desired crystal melting temperature will be lowered. There is a tendency for no improvement to be achieved. On the other hand, if the amount of the silane compound exceeds the above range, the crystallinity of the final stretch-crosslinked molded product tends to decrease, and the mechanical properties, part elastic modulus, tensile strength, etc. tend to decrease.

Furthermore, since silane compounds are expensive, they are economically disadvantageous. Furthermore, if the amount of the diluent is lower than the above range, the melt viscosity will become too high, making melt kneading and melt molding difficult, and the surface of the molded product will be extremely rough, easily causing stretching breakage and the like. On the other hand, if the amount of the diluent is larger than the above range, melt cross-linking will still be difficult and the stretchability of the molded product will be poor.

The above-mentioned chemicals may be blended into ultra-high molecular weight polyethylene by any method6.For example, a silane compound, a radical initiator, and a diluent may be blended at the same time and melt cross-mixing may be performed; There is a method in which the agent is first blended and then a diluent, or conversely, a diluent is first blended into ultra-high molecular weight polyethylene, and then a silane compound,
and a method of blending a radical initiator.

Melt kneading is generally preferably carried out at a temperature of 150 to 300°C, particularly 170 to 270°C; at temperatures lower than the above range, the melt viscosity becomes too high and melt molding becomes difficult; In this case, the molecular weight of ultra-high molecular weight polyethylene decreases due to thermal degradation, making it difficult to obtain a molded article with high elastic modulus and high strength. The blending may be carried out by dry blending using a Henschel mixer, a V-type blender, etc., or by melt mixing using a single-screw or multi-screw extruder.

Melt forming is generally carried out by melt extrusion. For example, filaments for drawing can be obtained by melt extrusion through a spinneret, and films, sheets or tapes for drawing can be obtained by extrusion through a flat die or ring die. By extruding the obtained product through a circular die, it is possible to obtain a tube for stretch blow molding (
The present invention is particularly useful for producing drawn filaments, in which case the melt extruded from the spinneret can be subjected to drafting, ie, drawing in the molten state. Extrusion speed vo of molten resin in the die orifice and winding speed V of the cooled and solidified ±unstretched material
The draft ratio can be defined by the following formula.

Draft ratio = V/vo, (2)
The draft ratio depends on the temperature at which the mixture reaches temperature, the molecular weight of the ultra-high molecular weight polyethylene, etc., but is usually 3 or more, preferably 6 or more.

Of course, melt molding is not limited to extrusion molding, and in the case of manufacturing various stretch molded containers, it is also possible to manufacture preforms for stretch blow molding by injection molding. The molded product can be cooled and solidified by forced cooling means such as air cooling or water cooling.

Stretching The unstretched molded product of silane-grafted ultra-high molecular weight polyethylene thus obtained is stretched. The degree of stretching treatment is
Of course, the ultra-high molecular weight polyethylene of the molded article is effectively imparted with molecular orientation in at least one axis direction.

The stretching of the silane-grafted polyethylene molded article is generally carried out by 4
It is desirable to carry out the heating at a temperature of 0 to 160°C, particularly 80 to 145°C. Air, water vapor, or a liquid medium can be used as the heating medium for heating and maintaining the unstretched compact at the above temperature. .

However, as a heating medium, a solvent capable of eluting and removing the diluent mentioned above and whose boiling point is higher than the melting point of the molded article composition, specifically decalin, decane, kerosene, etc., is used to stretch the material. By carrying out this operation, it is possible to remove the above-mentioned diluent, eliminate stretching unevenness during stretching, and achieve a high stretching ratio, which is preferable.

Of course, the means for removing excess diluent from ultra-high molecular weight polyethylene is not limited to the method described above.
Excess diluent in the molded product can be removed by a method of stretching after treatment with a solvent such as heptane, hot ethanol, chloroform, or benzene, or by a method of treating the stretched product with a solvent such as hexane, heptane, hot ethanol, chloroform, or benzene. The removal can be carried out effectively and a stretched product with high elastic modulus and high strength can be obtained.

The stretching operation can be performed in one stage or in multiple stages of two or more stages. Although the stretching ratio depends on the desired molecular orientation effect, satisfactory results can be obtained if the stretching operation is performed at a stretching ratio of generally 5 to 80 times, particularly 10 to 50 times.

In the case of uniaxial stretching operations such as filament, tape, or uniaxial stretching, tension stretching can be performed between rollers with different circumferential speeds, and in the case of biaxially stretched films, stretching can be carried out in the longitudinal direction between rollers with different circumferential speeds. In addition to tensile stretching, tensile stretching is also performed in the transverse direction using a tenter or the like. Biaxial stretching by the inflation method is also possible. Furthermore, in the case of a three-dimensional molded product such as a container, a biaxially stretched molded product can be obtained by a combination of axial stretching and expansion stretching in the circumferential direction.

Crosslinking Treatment According to the present invention, a silanol condensation catalyst is impregnated into the molded product during or after the stretching, and then the stretched molded product is brought into contact with moisture to effect crosslinking.

As the silanol condensation catalyst, those known per se are used, such as dialkyltin dicalgexylate such as diptyltin tholaurate, butyltin noacetate, and sibutyltin dioctoate; organic titanates such as tetrabutyl titanate; lead naphthenate, etc. be able to. These silanol condensation catalysts can be effectively impregnated into unstretched molded bodies or stretched molded bodies by contacting them in a state dissolved in a liquid medium. If the processing is carried out in a liquid medium,
By dissolving the silanol condensation catalyst in this liquid medium for stretching, it is possible to impregnate the molded body with the silanol condensation catalyst at the same time as the stretching operation. It is believed that diluents such as waxes act to promote uniform impregnation of the silanol condensation catalyst into the compact.

The amount of the silanol condensation catalyst impregnated into the molded article may be a so-called catalytic amount, and it is difficult to directly specify the amount, but in general, the amount of silanol condensation catalyst impregnated into the molded article is either unstretched or a stretching agent in a liquid medium that comes into contact with the molded article. 10 to 100% by weight, especially 25 to 7%
Satisfactory results are obtained by adding a silanol condensation catalyst in an amount of 5% by weight and contacting the molded body with this liquid medium.

The crosslinking treatment of the stretched molded article is carried out by bringing the stretched molded article of silane-grafted ultra-high molecular weight polyethylene impregnated with a silanol synthesis catalyst into contact with moisture. There are no particular restrictions on the conditions for this crosslinking treatment, but generally a long treatment time is required at a low treatment temperature. Advantageously, contact with moisture takes place. For this purpose, moisture is preferably applied to the drawn body in the form of hot water or hot steam. During this crosslinking treatment, the stretched molded product may be placed under restraint conditions to prevent orientation relaxation, or conversely, orientation relaxation may occur to some extent under unrestricted conditions.

Molecular Orientation - Silane Crosslinked Molded Product After the stretched molded product has been crosslinked, if it is further stretched (usually three times or less), mechanical strength such as tensile strength is further improved.

The molecularly oriented and silane-crosslinked ultra-high molecular weight polyethylene molded article according to the present invention exhibits a crystal melting peak (Tp) even at a much higher temperature than the original crystal melting temperature (Tm) of ultra-high molecular weight polyethylene under restraint conditions. It has the surprising characteristic of showing

The original crystal melting temperature (Tm) of ultra-high molecular weight polyethylene can be determined by a method of completely melting the molded body, cooling it to relax the molecular orientation in the molded body, and then raising the temperature again, the so-called differential scanning calorimetry method. It can be found in the second run where the plan fails.

Furthermore, the constraint condition refers to a condition in which no active tension is applied to the molded body, but the end portions are fixed so as to prevent free deformation.

As is clear from FIG. 4 explained above, the molded article according to the present invention has a crystalline melting temperature (
have at least two crystal melting peaks (Tp) at temperatures at least 10° C. higher than Tm), and the heat of fusion based on the total heat of fusion of these crystal melting peaks (TP) K is 40% or more, in particular 60% It has the above characteristics.

Generally, the crystal melting peak (Tp
) is the temperature range Tm -) -35°C to Tm + 120
It often appears as two peaks: a high-temperature side melting peak (Tpl) at °C and a low-temperature peak (Tpz) in the temperature range Tm + 10 °C to Tm + 35 °C, and the Tm melting peak itself is extremely small.

Note that the high temperature side melting zone (Tp l) is related to the amount of silane grafted in the molded body, and when the amount of silane grafted is small, a clear maximum point (peak) does not appear on the melting curve, but a broad maximum point (peak). Alternatively, it often appears as a shoulder or tail on the high temperature side of the low temperature side melting zone (Tp2) over a temperature range of Tm + 35°C to Tm + 120°C.

Furthermore, when the melting peak of Tm is extremely small, it may be hidden behind the melting peak shoulder of TPt and cannot be confirmed. Even if there is no Tm melting peak, there will be no problem with the functionality of the ultra-high molecular weight polyethylene molded product.

High temperature side melting peak (Tpl) and temperature range Tm + 10 at Tm + 35°C to Tm + 120 C
'C ~ Tm + 35℃ low temperature side melting peak (Tp
z) may be further divided into two or more melting peaks depending on sample preparation conditions and melting point measurement conditions.

These high crystal melting peaks (Tps - TP2) act to significantly improve the heat resistance of the ultra-high molecular weight polyethylene molded product, but they also contribute to improving the strength retention rate after high-temperature thermal history. is the melting peak on the high temperature side (
Tpl).

Therefore, it is desirable that the sum of the heat of fusion based on the high temperature side melting peak (Tpl) in the temperature range Tm+35°C to Tm+120°C is 5 inches or more, particularly 10% or more, based on the total heat of fusion.

In addition, as long as the sum of the heat of fusion based on the high-temperature side melting peak (Tpl) satisfies the above-mentioned value, if the high-temperature side melting peak (Tpl) does not stand out as a main peak, the 9th minor peak Even if it becomes an aggregate or a broad peak, the heat resistance may be slightly lost, but the creep resistance is excellent.

In the present invention, the above-mentioned shift of the crystal melting peak to the high temperature side does not occur in a mere stretched polyethylene molded article or a mere stretched cross-linked polyethylene molded article, but when silane is grafted onto a polyethylene composition containing a diluent. This can be achieved by combining molecular orientation by stretching and silane crosslinking in this order.

The melting point and heat of crystal fusion in the present invention were measured by the following method.

The melting point was determined using a differential scanning calorimeter as follows. Differential scanning calorimeter is DSCI [! (]]'--manufactured by KinElmer Co., Ltd. was used.

The sample was restrained in the direction of edge orientation by winding approximately 3 cm around an aluminum plate measuring 4+4 m x 4 m and 100 μm thick. Next, the sample wrapped around an aluminum plate was enclosed in an aluminum man.
This was used as a sample for measurement. In addition, the same aluminum plate used for the sample was sealed in the normally empty aluminum T4 tube placed in the reference holder to maintain heat balance. Mazu sample at 30℃ for approx.
The temperature was maintained for 1 minute, and then the temperature was raised to 250°C at a temperature increase rate of 10'C/min, and the melting point measurement at the first temperature increase was completed. Subsequently, the temperature was maintained at 250°C for 10 minutes, then the temperature was lowered at a rate of 20°C/min, and the temperature was further lowered for 3
The sample was held at 0°C for 10 minutes, and then the temperature was raised a second time to 250°C at a rate of 10°C/min. At this time, the melting point was measured during the second heating (second run). After completion, the maximum value of the melting peak at this time was taken as the melting point. If it appears as a shoulder, draw a tangent at the inflection point immediately on the low-temperature side and the inflection point immediately on the high-temperature side of C, L, and take the intersection as the melting point.

In addition, the straight line (
Baseline) and the original crystalline melting temperature of ultra-high molecular weight polyethylene determined as the main melting peak during the second temperature rise (
Draw a perpendicular line to the point 10°C higher than the Tm), and let the low-temperature side area surrounded by these be based on the original crystal melting (Tm) of ultra-high molecular weight polyethylene, and the high-temperature and low-temperature area be based on the crystal melting (Tm) of the molded article of the present invention. It is based on the crystal melting (Tp) that exhibits the function, and the heat of fusion of each crystal was calculated from these areas. In addition, the heat of fusion based on the melting of Tp2 made by TPI is determined according to the above method, and the part surrounded by the perpendicular line from Tm + 10°C and the perpendicular line from Tm + 35°C is the heat of fusion based on the melting of Tp2, and the high temperature side part is The heat of fusion was similarly calculated based on the melting of TPt.

The degree of molecular orientation in a molded product can be determined by X-ray diffraction, birefringence, fluorescence polarization, etc. In the case of the stretched silane crosslinked filament of the present invention, for example, Yukichi Go, Teru Kubo, Kazuhiro Kubo: Industrial Chemistry The degree of orientation according to the half value, that is, the degree of orientation F = 9, which is detailed in the magazine Vol. 39, page 992 (1939): 3-90 degrees, where Ho is the strongest /# radrope on the equator. It is the half-width (') of the intensity distribution curve along the Debye ring of the surface.

The degree of orientation CF defined by CF) is 0.90 or more, especially 0.9
It is desirable for the molecules to be oriented in such a way as to have a molecular orientation of 5 or more in terms of heat resistance and mechanical properties.

In addition, the amount of silane grafted was 135
Extraction treatment was carried out in p-xylene for 4 hours at a temperature of ℃,
It can be determined by extracting and removing unreacted silane and diluent contained therein, and performing quantitative determination using a gravimetric method or an atomic absorption method. 81% by weight, 0.01 to 5% by weight, especially 0.035 to 3.
From the viewpoint of heat resistance, it is desirable that the weight is in the range of 5 -
That is, when the amount of grafting is less than the above range, the crosslinking density is lower than in the case of the present invention, while when it is more than the above range, the crystallinity decreases, and in either case, the heat resistance is insufficient. Become.

In the molecularly oriented silane crosslinked molded article of the present invention, the crystal melting temperature of at least some of the polymer chains constituting the molded article has shifted significantly to the high temperature side as described above, and therefore has extremely excellent heat resistance. The strength retention rate after being subjected to a heat history of 160°C for 10 minutes is 80 degrees or more, preferably the strength retention rate is 60 degrees or more after being subjected to a heat history of 180 degrees Celsius for 10 minutes, especially 80% or more, even 200℃
It exhibits surprising heat resistance, which is completely unexpected from conventional ultra-high molecular weight polyethylene, with a strength retention rate of 80 or more after being subjected to a heat history of 5 minutes.

Furthermore, the molded article of the present invention has heat-resistant creep properties, such as load resistance;
Under the conditions of 30% breaking load and temperature near 0℃, the uncrosslinked material becomes 1
While the molded product shows an elongation of 50% or more after standing for a minute, the elongation of the molded product is 30% or less, and even 20% or less, which is extremely excellent.

In addition, the molded product of the present invention further elongates and breaks after being left for 1 minute under the conditions of a load: 50% breaking load and a temperature of near 0°C, whereas an uncrosslinked product elongates and breaks within 1 minute. indicates 20% or less.

In addition, since this molded product contains grafted and crosslinked silanes, it has excellent adhesive properties, particularly with various resins9, and this fact can be seen in the examples described later. It will be easier to understand.

Furthermore, this molded body is made of ultra-high molecular weight polyethylene,
Moreover, since molecular orientation is effectively imparted, it is excellent in mechanical customization, and exhibits an elastic modulus of 20 GPa or more and a tensile strength of 1.2 GPa or more in the form of a drawn filament, for example.

(Effects of the Invention) The molecularly oriented and silane-crosslinked ultra-high molecular weight polyethylene molded article of the present invention is excellent in the combination of heat resistance, mechanical properties, adhesiveness, and the like. Thus, when a molded article in the form of a filament is used as a reinforcing fiber for various resins such as epoxy resin, unsaturated polyester, synthetic rubber, etc., it has better heat resistance and adhesive properties than conventional ultra-high molecular weight polyethylene drawn filaments. It is clear that this filament has a high strength and a low density, so it is superior to conventional glass fibers, carbon fibers, glass fibers, aromatic polyamide fibers, aromatic polyimide fibers, etc. It is particularly effective because it can be made lighter compared to molded molded products. Similar to composite materials using glass fiber etc., TJD
(Unit Dlrsctional) Laminated board, SMC
(5heet Mold Compound)
, BMC (Bulk Molding Cornpou)
nd), etc., and is expected to be used as a variety of composite materials in lightweight, high-strength fields such as automobile parts, structures for seats and yachts, and substrates for electronic circuits.

(Example) Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these embodiments as long as they do not go beyond the gist of the invention.

Example 1 Grafting and spinning ultra-high molecular weight polyethylene (intrinsic viscosity [η) = 8.2
0dt/! i) Powder: 100 parts by weight, vinyltrimethoxysilane (Shin-Etsu Chemical Exhibition): 10 parts by weight and 2
．． 5-dimethyl-2,5-no(t@rt-butylperoxy)hexane (manufactured by NOF: trade name, Barhexa 25
B): 0.1 parts] After uniformly blending 100 parts by weight of ultra-high molecular weight I-lyethylene, powder of No.
Melting point = 69°C): 370 parts by weight were added and mixed to obtain a mixture. Next, the mixture was melt mixed using a single screw extruder (screw diameter = 20 wrφ, L/D = 25) at a set temperature of 200°C, and then the melt was spun through a gouie with an orifice diameter of 2+w. Silang graft completed. The spun fibers were cooled and solidified in air at room temperature through 180 air gaps to obtain undrawn ultra-high molecular weight polyethylene silica/graft fibers. This undrawn yarn had a 8007'neal, a draft ratio at the time of spinning of 36.4, and a winding speed of 907q/m1n.

Determination of the amount of silane grafting 1
The ultra-high molecular weight polyethylene was heated and maintained at 35 DEG C. and dissolved in 200 g of p-xylene, then precipitated in excess hexane at room temperature to remove rough wax and unreacted silane compounds. After this, St weight% by gravimetric method
The amount of grafting determined was 0.57% by weight.

Stretching The grafted undrawn fibers spun from the ultra-high molecular weight polyethylene mixture by the method described above were drawn under the following conditions to obtain oriented drawn fibers. Two-stage stretching was carried out using a Godetstrol manufactured by Ohdai in a stretching tank using decane as a heating medium. At this time, the temperature inside the first drawing tank was 110°C, and the temperature inside the second drawing tank was 120°C.
'C, and the effective length of each cypress was 50 cm. During stretching, the rotational speed of the first godet roll was set to 0.5.
A fiber with a desired drawing ratio was obtained by changing the rotation speed of the third godet roll in m/min. In addition, the rotational speed of the second godet roll should be appropriately selected within the range that allows stable stretching, but the stretching ratio should be set at the same rate as that of the first godet roll and the third godet roll.
It was obtained by calculating the rotation ratio with the coptrol.

The resulting fibers were dried under reduced pressure at room temperature to form ultra-high molecular weight I-lyethylene silane grafted fibers.

Impregnation of cross-linking catalyst When further cross-linking the oriented fibers of the silane compound-grafted ultra-high polymer bar polyethylene that have been split in the above method, n-decane is used as a heating medium in the second stretching tank during stretching. using a mixture of equal amounts of Tubutyltin Thoraurate,
At the same time as paraffin wax was extracted, subbutyltin tholerate was impregnated into the fiber. The obtained fibers were dried under reduced pressure at room temperature until they were free of deca/odor.

After crosslinking, the fibers were left in boiling water for 12 hours to complete crosslinking.

Measurement of Dull Fraction 0.4 g of the silane cross-linked stretched ultra-high molecular weight polyethylene fiber obtained by the above method was placed in an Erlenmeyer flask equipped with a condenser containing 200 grams of T4 laxylene.
The mixture was stirred at boiling for 4 hours. Next, the insoluble matter was passed through a stainless steel wire mesh of 300 m@sh. After drying under reduced pressure at 80°C, it was weighed to determine the weight of insoluble matter. The dull fraction was calculated using the following formula.

The dull fraction of the above prepared sample was 51.4 cm.

Tensile modulus, tensile strength, and elongation at break were measured at room temperature (23°C) using an Instron universal testing machine model 1123 (Instron M). Sample length between clamps is 10
The tensile speed was 100/min at 0/min. However, the tensile modulus is the initial modulus. Fl required for calculation, 8ft
The cross-sectional area was determined by measuring the weight and length of the acid fibers, assuming the density of polyethylene as 0.96177 cm 2 .

Table 1 shows the physical properties of the silane-crosslinked stretched ultra-high molecular weight polyethylene fiber thus obtained.

Table 1 In addition, the original crystal melting temperature (Tm) of ultra-high molecular weight polyethylene, which is determined as the main melting peak during the second temperature rise, is 13
The temperature was 2.2°C, and the ratio of the heat of fusion based on 'rp to the total heat of fusion of the crystals, and the ratio of the heat of fusion based on TPI to the total heat of fusion of the crystals were 73% and 22%, respectively. At this time, the main temperature of TI)z was 151.0°C, and the main temperature of TPt was 226.5°C.

Figure 1 shows the melting characteristic curve during the first temperature rise of the ultra-high molecular weight polyethylene used in Example 1, which was formed into a 100μ thick press sheet at 200°C, and Figure 2 shows the melting characteristic curve, which will be described later. The melting characteristic curve of the ungrafted stretched ultra-high molecular weight polyethylene fiber prepared in Comparative Example 1 at the first temperature increase is shown. ! In addition, FIG. 3 shows that the unstretched arm rough-in wax grafted with silane in Example 1 was extracted with hexane at room temperature and formed into a press sheet by press molding, and then impregnated with diptyltin dilaurate. The melting characteristic curve at the first temperature increase of the sample crosslinked by the method is shown below. FIG. 4 shows the melting characteristic curve of the silane-crosslinked stretched ultra-high molecular weight polyethylene fiber prepared in Example 1 during the first temperature rise, and FIG. 5 shows the melting characteristic curve of the fiber during the second temperature rise ( The melting characteristic curve of the second run) is shown.

Figure 6 also shows the temperature rise from the first temperature rise to the second self-rise mf critical 7.
．． 1-t shows the key of the iron flood song.

Evaluation of Adhesiveness Evaluation of adhesiveness was carried out by the drawing method. The resin to be bonded was Araldite and Ravid (epoxy resin, manufactured by Showa Kobunshi Co., Ltd.), and the method was based on the JIS L-1017 chemical fiber tire cord test [Method Q, Adhesion A method (P test). The results are shown in FIG.

The silane-crosslinked stretched ultra-high molecular weight polyethylene fiber (Sample-1) prepared in this example has about three times the adhesion as compared to the stretched ultra-high molecular weight f IJ ethylene fiber (Sample-2) prepared in Comparative Example 1 described later. It can be seen that the force (pulling force) has been improved.

Evaluation of creep characteristics The creep test was performed using a thermal stress strain measuring device TMA/5SIO.
(manufactured by Seiko Electronics Co., Ltd.)
, at an ambient temperature of 70°C. The results at a load of 500 MPa are shown in FIG. 8, and the results at a load of 30% of the breaking load are shown in FIG. 9. The silane-crosslinked stretched ultra-high molecular weight polyethylene fiber (Sample-1) prepared in this example is the same as the hole-stretched ultra-high molecular weight polyethylene fiber (Sample-1) prepared in Comparative Example 1 described below.
It can be seen that the creep characteristics are significantly improved in both cases compared to 2).

Table 2 shows the elongation at 1 minute, 2 minutes, and 3 minutes immediately after loading in a creep test conducted at an ambient temperature of 70° C. and a load equivalent to more than 50 times the chamber load at room temperature.

Table 2 Samples 117, 4 28, 2 38, 6 The thermal history test was conducted by leaving the samples in a gear open (arm-effect open: manufactured by Tabai Seisakusho). The sample was approximately 3 m long, and a plurality of pulleys were installed at both ends of a stainless steel piece, and both ends of the sample were fixed by folding it back over the piece. At this time, both ends of the sample were fixed to about 17', and no tension was actively applied to the sample. I will show the results to 3.

Table 3 It can be seen from Table 3 that it has surprising heat resistance and strength retention properties.

Measurement of degree of orientation by X-ray diffraction The fibers were wound around a Phillips holder 10 to 20 times, one side was cut off, and the fibers were bundled and used for measurement. The degree of orientation is (110
) The surface reflection was measured with a diffractometer and the reflection intensity distribution was determined. The calculations followed the method of Wu et al. described above. The degree of orientation determined in this way was 0.955.

Observation of crystal melting using a polarizing microscope A sample for observation was prepared by winding a fiber sample around a glass plate with a width of about 211I+1 and a thickness of about 0.5 m and fixing both ends. Next, the observation sample was placed on a hot stage (manufactured by Metra,
The silane-crosslinked stretched ultra-high molecular weight polyethylene fiber prepared in this example was observed under a microscope under polarized light while heating at a temperature increase rate of 10°C/weight n on a model PF20). It can be confirmed (Figure 10) that 2
At 20°C, it becomes a dark field, confirming the melting of the crystal.

Comparative Example 1 Preparation of drawn ultra-high molecular weight polyethylene fiber Ultra-high molecular weight polyethylene (intrinsic viscosity [η] = 8.20 > powder: 1
00 parts by weight and 320 parts by weight of the paraffin wax powder described in Example 1 were spun by the method described in Example 1. At this time, the draft ratio is 25 times and the undrawn yarn fineness is 100.
Just in case it's 0 denier. Then, the fibers were drawn in the same manner to obtain drawn fibers. The physical properties of the obtained fibers are shown in Ken 4.

Table 4 The melting characteristic curve of this fiber (sample-2) is shown in FIG.

The adhesive strength was measured by the method described in the section ``Evaluation of Adhesion'' in Example 1. The results are shown in FIG. 7 together with Example 1. The creep properties were measured by the method described in the section "Evaluation of creep properties" in Example 1. 500MPa
The results under load are shown in FIG. 8, and the results under a breaking load of 30 inches are shown in FIG. 9.

In addition, in the measurement of creep properties conducted in the same manner as in Example 1 (ambient temperature = 70°C, load = 50 inches of breaking load at room temperature), the sample broke immediately after loading. Figure 2 shows the DSC melting characteristic curve during the first temperature increase.
The original crystal melting temperature Tm, which is determined as the main melting peak during the second heating, is 132.2°C, and the ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on Tpl to the total heat of fusion of the crystals Well, they are 32.1 inches and 1.7 inches, respectively.

The strength retention rate after heat history was measured using the method described in the section ``Strength retention rate after heat history'' in Example 1. In order to ensure that the crystals melted, observation of crystal melting under a polarizing microscope was carried out in the same manner as described in the section of Example 1, <Observation of crystal melting using a polarizing microscope>. Crystals were observed at 150°C (Fig. 11), but a dark field appeared at around 180°C.

Comparative Example 2 Preparation of silane cross-linked stretched polyethylene fiber
Density: 0.955 fl/cm, intrinsic viscosity [7ri]
= 2.30 dllf I) 2100 parts by weight of the powder and 10 parts by weight, 0.11 parts by weight, and 33 parts by weight of the vinyltrimethoxysilane, mother oxide and rough-in wax powders described in Example 1, respectively. Parts by weight were mixed uniformly, and then III was prepared by the method described in Example 1.
The fibers were spun using a + die to obtain undrawn fibers of 1800 denier. The grafting rate at this time was 1.23 wt as determined by Sii Keichi. It was then stretched as described in Example 1 and impregnated with a catalyst to form fibers and complete the crosslinking. The obtained fiber properties are shown in Table 5.

Table 5 The strength retention rate after heat history was measured by the method described in the section ``Strength retention rate after heat history'' in Example 1. The results are shown in Table 6.

Shallow 6 In addition, when the temperature was 180°C, it melted even after being left for 10 minutes. Compared to Sample-1 of Example 1, the molecular weight is lower, the strength before heat history is lower, and the strength retention rate after heat history is also inferior.

In addition, when the cyclic f% property was measured by the method described in Example 1 (ambient temperature = 70°C, load equivalent to more than 50% of the breaking load at room temperature), the sample broke immediately after loading. did. FIG. 12 shows the υSC melting characteristic curve #l during the first temperature rise. The original crystal melting temperature Tm, which is determined as the main melting peak during the second heating, is 128.0°C.
The ratio of the heat of fusion of Mi based on p to the total heat of fusion of the crystals and the ratio of the heat of fusion based on Tpt to the total heat of fusion of the crystals are 47% and 9.5%, respectively. Similarly to Example 1, a creep test was conducted at an ambient temperature of 70° C. with a load equivalent to 50% of the breaking load at room temperature, and the sample broke immediately after the load was applied.

Comparative Example 3 Preparation of Cross-linked Stretched Fiber with E-Oxide From the undrawn yarn prepared by the method described in Comparative Example 1, Rough-in wax was extracted using excess hexane. The undrawn yarn was dried at room temperature under reduced pressure.

Subsequently, the yarn was impregnated with dicumyl peroxide (manufactured by Mitsui Petrochemical Industries, Ltd., trade name: Mikata DCP) in a 20% by weight acetone bath and dried again at room temperature under reduced pressure to obtain an undrawn yarn. The content of dicumyl peroxide measured by the gravimetric method was 0.
．． It was 51 weight jt%.

Subsequently, three Gatsutrols were used to infrared gold image furnace (manufactured by Shinku Riko Co., Ltd.: RHL-E461).
) was used as a stretching tank to carry out two-stage stretching.

At this time, the temperature inside the first drawing tank was 110°C, the temperature in the second drawing tank was 145°C, and the effective length of each cypress was 42 holes. During stretching, the first step is to set the rotational speed of the puttrol to 0.
．． Fibers with the desired draw ratio were obtained by adjusting the rotational speed of the third godet roll as 5 m/m1n. Second, the rotational speed of the Guttrol was appropriately selected within a range that allowed for stable stretching. However, the stretching ratio was calculated from the rotation ratio of the first Gatsutrol and the third Gatsutrol. Table 7 shows the physical properties of the obtained fibers.

Table 7 In addition, the original crystal melting temperature Tm determined as the main melting peak during the second temperature rise is 133.1°C, and the ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the heat of fusion based on Tps to the total crystal The proportions to the heat of fusion were 73% and 2%, respectively. The strength retention rate after heat history was measured by the method described in the section ``Strength retention rate after heat history'' in Example 1. When heated at 180° C. for 10 minutes, the fiber shape remained, but the fibers were fused.

Example 2, ultra-high molecular weight polyethylene (intrinsic viscosity (η) = 8.20d
Vinyltris(methoxyethoxy)silane (Shin-Etsu Chemical &&): 10 parts by weight of powder 2 of i/11)
Parts by weight and 2,5-dimethyl-2,5-di(tart-
Butylyloxynohexane (manufactured by NOF: trade name)
] Arm-Hexa 25B: 0.111i: After uniformly blending the base part, paraffin wax powder (manufactured by Nippon Seiro Co., Ltd.: trade name, Luvax 1266 JI point = 69°C) is added to 100 parts by weight of ultra-high molecular weight polyethylene. :235Xit parts were added and mixed to obtain a mixture. Then, the mixture was passed through a screw extruder (screw diameter = 20 mm, L/D = 25 mm).
Melt-kneading and grafting were performed at a set temperature of 250° C., followed by spinning, stretching, and crosslinking by the method described in Example 1 to obtain silane crosslinked stretched ultra-high molecular weight polyethylene fibers.

Table 8 shows the physical properties of the fiber thus obtained.

Table 8 In addition, the original crystal melting temperature Tm of ultra-high molecular weight polyethylene, which is determined as the Dozo beak during the second temperature rise, is 132. I
C, the ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on Tpt to the total heat of fusion of the crystals were 59% and 11%, respectively. At this time, Tp2 was removed at 148.1°C, and the main TPs were removed at 170.5°C. Furthermore, the melting characteristic curve at the first temperature increase is shown in FIG. Tables 9 and 10 show the silane graph) i (8i weight %), the glue fraction, and the tensile property retention rate measured by the method described in Example 1.

Table 9 Table 10 Also, as in Example 1, a creep test was conducted at an ambient temperature of 70° C. with a load equivalent to 50% of the breaking load at room temperature. Table 11 shows the elongation 1 minute, 2 minutes, and 3 minutes after loading.

Table 11 Sample Time (min) Elongation (H) Sample-2110
,8 212,6 313,8 The degree of orientation determined by the method of Example 1 was 0.950.

Example 3 Ultra-high molecular weight polyethylene (limiting viscosity [η) = 15.
5dv11) powder = 100 parts by weight, vinyltriethoxysilane (manufactured by Shin-Etsu Chemical): 3 parts by weight and 2.5 parts by weight
-Dimethyl-2,5-di(tert-butyloxy)hexane (manufactured by NOF: trade name, Perhexa 25B
): After uniformly blending 0.1 part by weight with 100 parts by weight of ultra-high molecular weight polyethylene, powder of noni rough-in wax (manufactured by Nippon Suro: trade name, Luvax 1266, melting point = 69°C): 400 parts by weight were added and mixed to obtain a mixture. Next, the mixture was heated to a set temperature of 250 using a screw extruder (screw diameter = 20 fins φ, L/D = 25).
Melt-kneading and grafting were carried out at 0.degree. C., followed by spinning, drawing and crosslinking according to the method described in Example 1 to obtain silane crosslinked drawn ultra-high molecular weight polyethylene fibers. The physical properties of the fiber thus obtained are shown in Figure 12.

Table 12 Sample -617.6 de=-#16.0 times 2.00
GP & elastic modulus elongation 50.88 GPa 5.02 % In addition, the crystal melting temperature Tm of ultrapolymer*ysv ethylene rice, which is determined as the main melting peak during the second temperature rise, is 133
．． The ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on Tps to the total heat of fusion of the crystals are 64 and 12%, respectively.
It was 4%. T at this time? is 152.2°C, and T
The main value of p□ was 181.4°C. Further, the DSC melting characteristic curve during the first temperature increase is shown in FIG. The amount of silanelast (S) measured by the method described in Example 1
Tables 13 and 14 show the t weight %), the glue fraction, and the tensile property retention rate.

Table 13 Sample silanelast amount Glue fraction sample-6
0,068% 71.6chi Table 14 (Retention rate %) (Retention rate Chi) 24.18 6.66 (48.0chi) (133chi) Also, as in Example 1, at room temperature at an ambient temperature of 70°C A creep test was conducted at a load equivalent to 50% of the breaking load. Table 15 shows the elongation 1 minute, 2 minutes, and 3 minutes after loading.

Table 15 Sample-219,8 211,0 312,0 The degree of orientation determined by the method of Example 1 was 0.964.

Example 4 Ultra-high molecular weight polyethylene (intrinsic viscosity [η] = 8.20
di/i) powder: 100 parts by weight of vinyl)
After uniformly blending IJ ethoxysilane (+i Etsu Kagaku): 5-weight xh and dicumyl nose oxide (NOF Hibi: trade name, Permil P): o, os heavy lid part, 100 parts by weight of ultra-high molecular weight polyethylene. Against this, ・Zorafuin Wax powder (manufactured by Nippon Kenwa: product name, Luvax 12
66, melting point = 69°C): 400 parts by weight were added and mixed to obtain a mixture. Next, the mixture was melt-kneaded and grafted using a single-screw extruder (screw diameter = 20 mφ, L/[) = 25] at a set temperature of 230°C, and subsequently, according to the method described in Example 1. Spinning, drawing, and crosslinking were performed to obtain silane crosslinked drawn ultra-high molecular weight polyethylene fibers. Table 16 shows the physical properties of the fibers obtained in this way.

Table 16 Sample Fineness Stretching ratio Strength denier
times GPa sample-79,111,192
, 14 Elastic modulus Elongation GPa 43.14 5.85 Furthermore, the original crystal melting temperature Tm of ultra-high molecular weight polyethylene, which is determined as the King's melting peak during the second temperature rise using a differential scanning calorimeter, is 133.2°C. The ratio of the heat of fusion based on Demeri Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on TPt to the total heat of fusion of the crystals are each 71
．． 5% and 19.0% were rare. This and @Tp* are 150
．． 3°C, and the main TPt was 234.7°C. In addition, the DSC melting characteristic curve during the first temperature increase was
It is shown in Figure 5. The silane graft amount (Si weight %), the glue fraction, and the tensile property retention rate measured by the method described in Example 1 are shown in Table 17.18.

Table 17 Sample Silang graft amount Glue portion 8 sample-7
0,044% 94.9% - Table 18 Sample Oven temperature Standing time 'Cmin Sample - 7180℃ 10 160℃ 10 (Retention rate Chino (Retention ``4%) (Retention ``4%) 1.4
4 24.14 7.301.53
28.81 6.90
Further, as in Example 1, a creep test was conducted at an ambient temperature threshold of 70° C. and a load equivalent to 50 inches of the breaking load at room temperature. Table 19 shows the elongation 1 minute, 2 minutes and 3 minutes after loading.

Sample Time (min) Elongation (%) Sample-711
The degree of orientation determined by the method of Example 1 was 0.954.

Example 5 Ultra-high molecular weight polyethylene (intrinsic viscosity [η) = 8.20d
i/i) powder: 100 parts by weight, vinyltriethoxysilane (manufactured by Shin-Etsu Chemical) = 5 parts by weight and 2.5-methyl-2,5-di(tart-butylperoxy)hexyne-3 (Japan) Made of oil: Product name.

Perpekin 725B): After uniformly blending 0.05 parts by weight, with respect to 100 parts by weight of ultra-high molecular weight polyethylene,
400 parts by weight of rough-in wax powder (manufactured by Nippon A-Ro Co., Ltd.: trade name, Luvax 1266, melting point = 69°C) was added and mixed to obtain a mixture.Then, the mixture was passed through a screw extruder (Screw Lx- Diameter -20waφ, L/D=25)
Melt kneading and grafting were carried out at a set temperature of 200°C using a
Stretching and crosslinking were performed to obtain a silica/crosslinked stretched ultra-high molecular weight polyethylene fiber. Table 20 shows the physical properties of the fiber thus obtained.

Table 20 Sample Consistency Stretching ratio Strength denier
times GPa sample-86,416,74
3,34 Elastic elongation GPa % 74.32 5.87 In addition, the original crystal melting temperature Tm of ultra-high molecular weight polyethylene, which is determined as the main melting peak during the second heating, is 133
．． The ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on Tpl to the total heat of fusion of the crystals were 76.2% and 6.2%, respectively. T at this time? was 153.1°C. Also T
Although no main peak of pt was observed, Tm + 3
A shoulder peak of TPz extending from 5°C to the high temperature side was observed. The endothermic characteristic curve at the -th temperature increase is shown in FIG.

The silane graft amount, glu fraction, and tensile property retention measured by the method described in Example 1 are shown in Table 21.22.

Table 21 Sample Silang graft amount Glue fraction sample -80,013% 42.5chi Table 22 Temperature °C min (retention rate %) Elastic modulus GPa
Elongation Chi (retention rate %) (retention rate Chi) 49.11 5.82 Similarly to Example 1, a cleave test was conducted at an ambient temperature of 70°C with a load equivalent to 50% of the breaking load at room temperature. . Table 23 shows the elongation 1 minute, 2 minutes, and 3 minutes after loading.

Table 23 Sample Time (min) Elongation (%) Sample -818,4 210,4 312,8 Also, the degree of orientation determined by the method of Example 1 was 0.980.

Example 6゜Ultra high molecular weight polyethylene (intrinsic viscosity [η]=8.20d
l/i) powder: 100 parts by weight of vinyl l-IJ
Ethoxysila/(manufactured by Shin-Etsu Chemical) = 1 part by weight and 2.5-
Dimethyl-2,5-di(tart-butyloxy)
Hexine-3 (Nippon Oil & Fats Co., Ltd.: trade name, Perhexine 25)
B): After uniformly blending 0.05 parts by weight, paraffin wax powder (manufactured by Hiki Seiro Co., Ltd., trade name, Luvax 1266,
Melting point = 69°C) = 400 parts by weight were added and mixed to obtain a mixture. Then, the mixture was heated to a set temperature of 230 using a screw extruder (screw diameter = 20 wφ, diameter = 25).
Melt-kneading and grafting were carried out at 0.degree. C., followed by spinning, drawing and crosslinking according to the method described in Example 1 to obtain silane crosslinked drawn ultra-high molecular weight polyethylene fibers. Table 24 shows the physical properties of the fiber thus obtained.

24 Sample-95,623,503,22 Elastic modulus Elongation GPa % 80.26 4.75 In addition, the original crystals of ultra-high molecular weight polyethylene determined as the main melting peak during the second temperature rise using a differential scanning calorimeter The melting temperature Tm is 134.4°C, and the ratio of the heat of fusion based on Tp to the total heat of fusion and the ratio of the heat of fusion based on Tpl to the total heat of fusion of the crystals are each 75.4%.
and 8.3%.

At this time, Tp2 was 154.0°C.

Also, no main peak of Tpl was observed, but Tm+
A shoulder peak of Tp2 was observed from 35°C to the high temperature side.

Table 2 shows the amount of silane craft (81% by weight), glue fraction, and tensile property retention measured by the method described in Example 1.
5.26.

Table 25 Sample -90,015% 77.6%Table 26 Elastic modulus GPa Elongation Chi (Retention rate Chi) (Retention rate %) Also, as in Example 1, breaking load at room temperature at ambient temperature near 0°C A creep test was conducted under a load equivalent to 50% of the above. Table 27 shows the elongation 1 minute, 2 minutes, and 3 minutes after loading.

Table 27 Sample-917.4 211.0 Comparative Example 4 Ultra-high molecular weight polyethylene (intrinsic viscosity [η] = 8,20
di/9) powder = 100 parts by weight, paraffin wax powder (manufactured by Nippon Seiro Co., Ltd., trade name Luvax 126)
6, melting point = 69° C.): 235 parts by weight were added and mixed to obtain a mixture. Then, the mixture was passed through a single screw extruder =
20 mφ, VD=25), the mixture was melt-kneaded and spun at a set temperature of 200°C.

The draft ratio during spinning is 31 times and the winding speed is 15 m.
The undrawn yarn produced at /min, p had a denier of about 1000. Subsequently, the undrawn yarn was drawn in two stages in a drawing tank using n-decane as a heat medium using a godet roll on a stand, and further drawn in three stages in total using triethylene glycol.

At this time, the first drawing tank temperature was 110°C, the second drawing tank temperature was 120°C, and the third drawing temperature was 140°C, and the effective length of each cypress was 50cW1. During stretching, the rotational speed of the first godet roll was set at 0.5 m/min.
By changing the rotational speed of the fourth godet roll, fibers with the desired draw ratio were obtained. Further, the rotational speeds of the second and third puttrols were appropriately selected within a range that allowed stable stretching. However, the first drawing ratio was calculated based on the rotation ratio of the puttrol and the third godetroll. Table 28 shows the physical properties of the fiber thus obtained.

Table 28 Sample Fineness Stretching ratio Strength denier times GPa Sample-108,025,02,29 Elasticity modulus Elongation GPa 82.0 Original ultra-high molecular weight polyethylene determined from the main melting peak at the second temperature increase in 4.1 The crystal melting temperature Tm is 133.1°C, and the ratio of the heat of fusion based on Tp to the total heat of fusion and the ratio of the heat of fusion based on TpI to the total heat of fusion of the crystals are 72.0 and 2.2S''11s6z, respectively. (7) Tp2 was 155.0°C @ Table 2 shows the tensile property retention y4 measured by the original method described in Example 1.
9.

Table 29 Elastic modulus GPa Elongation (retention rate %) (retention rate L) In addition, a creep test was performed in the same manner as in Example 1 (atmosphere temperature = 70°C, load = load equivalent to 50% of the breaking load at room temperature). ), and 50 seconds after loading, it elongated to 49% and broke.

Comparative Example 5 100 parts by weight of the polyethylene powder used in Comparative Example 2, 1 part each of vinyltrimethoxysilane described in Example 1, and Tsucumyl peroxide (manufactured by Mikata Petrochemical Industries, trade name Mikata DCP) 0.0 part by weight and 0.03 part by weight were uniformly mixed, and then granulated using a 20-kilometer extruder at a set temperature of 185° C. to obtain grafted pellets.

Then, it was used in Comparative Example 2 in the same manner. d Liethylene powder =
1.0 parts by weight of butyltinnolaurate was uniformly mixed with 100 parts by weight, and granulation was performed at a temperature of 190° C. according to the method described above to obtain a crosslinked catalyst master patch. Thereafter, 95 parts of the grafted pellets and 51 parts of the cross-linked catalyst master patch were uniformly mixed, and spinning was attempted at a set temperature of 270 DEG C. using a spinning machine equipped with a 25-inch screw. However, polyethylene solidifies in the spinning machine,
It could not be spun.

Comparative Example 6 Using the silane grafted pellets prepared in Comparative Example 5,
A grafted undrawn yarn was obtained by spinning using a melt tension tester (manufactured by Toyo Kumiki Co., Ltd.). At this time, the nozzle diameter was 2 m and the set temperature was 250°C. The film was then stretched under the following conditions to obtain oriented and stretched pJ fibers. Stretching was carried out using a pair of cop rolls in a stretching tank using triethylene glycol as a heating medium. At this time, the temperature inside the drawing tank was 102°C, and the effective length of the tank was 50 cPn. The rotational speed of the delivery godet roll was 0.5 m/min, and the stretching ratio was determined by the method described in Example 1. The obtained drawn fibers were washed with warm water and dried at room temperature.

The drawn yarn was then immersed in a 3011% diptyltin dilaurate n-decane solution under a 70-g vacuum to impregnate the water crosslinking catalyst. The resulting water-crosslinked, catalytically immersed, grafted drawn fibers were then left in water for one day to complete water-crosslinking. The physical properties of the silica/crosslinked drawn polyethylene fiber thus obtained are shown in Cloth 30.

Table 30 In addition, the original crystal melting temperature Tm of polyethylene, which is determined as the king melting peak during the second temperature rise using a differential scanning calorimeter, is filtered at 131.5°C, and the ratio of the heat of fusion based on Tp to the total heat of fusion of the crystals and the ratio of the heat of fusion based on TPt to the total heat of fusion of the crystals is 6.4 and 0, respectively.
It was Chi. The original crystalline melting temperature Tm of polyethylene is
Despite the results of cross-linking and stretching, the melting point could not be increased and a main peak could not be obtained in the TPt region. Furthermore, no traces of peaks or shoulders due to melting could be observed in the 'rpl region.

Furthermore, no subpeaks peculiar to the uninvented molded product were observed in the exothermic characteristic curve during recrystallization for the second temperature increase and the endothermic characteristic curve (second run) during the second temperature increase.

The endothermic characteristic curve during the first self-heating, the exothermic characteristic curve during the process of moving to the second temperature increase, and the endothermic characteristic curve during the second temperature increase are shown in FIGS. 17 to 19, respectively. Figures 17 to 19
As is clear from the figure, the characteristic peak or shoulder on the high temperature side with respect to the main peak observed in the stretched molded product of the present invention was not observed at all in the stretched molded product of this comparative example.

The glu fraction determined by the method of Example 1 was 3.5%.

Further, the fiber melted at 140° C. and did not exhibit retention of tensile properties at high temperatures.

[Brief explanation of drawings]

Figure 1 is a diagram showing the melting characteristic curve of the raw material ultra-high molecular weight polyethylene, Figure 2 is a diagram showing the melting characteristic curve of the ultra-high molecular weight polyethylene drawn filament of Figure 1, and Figure 3 is a diagram showing the melting characteristic curve of the ultra-high molecular weight polyethylene of Figure 1. Figure 4 is a diagram showing the melting characteristic curve of the drawn filament obtained by grafting silane to the ultra-high molecular weight polyethylene shown in Fig. Diagram showing a characteristic curve. Figure 5 is a diagram showing the melting characteristic curve when the sample in Figure 3 is subjected to the second heating measurement. Figure 6 is a graph showing the crystallization characteristic curve when the sample in Figure 3 is subjected to the first temperature cooling measurement. Figure 7 is a diagram showing the relationship between embedding length and pull-out force in the adhesion test for Sample 1 and Sample 2 of Example 1. Diagrams showing the measurement results of creep properties for Sample 1 and Sample 2 of Example 1 (Figure 8 shows the load at 500 MPa, Figure 9 shows the breaking load at 300 MPa measured at room temperature).
These are the results measured with a load of 0%. ), Figure 10 shows the molecular orientation and silane cross-linked ultra-high molecular weight polyethylene filament of the present invention (Example 1).
11 is a polarized light micrograph showing the presence of a crystal structure at 150°C for the ultra-high molecular weight polyethylene filament of Comparative Example 1, and FIG. 12 is a polarized light micrograph showing the presence of a crystal structure in Comparative Example 2 Figure 13 is a diagram showing the melting characteristic curve of the silane-crosslinked polyethylene filament; Figure 13 is a diagram showing the molecular orientation of Example 2 and the melting characteristic curve of the silane-crosslinked ultra-high molecular weight polyethylene filament; Figure 14 is the molecule diagram of Example 3. Figure 15 is a diagram showing the melting characteristic curve of the molecular orientation and silane crosslinked ultra-high molecular weight polyethylene filament of Example 4. Figure 16 is a diagram showing the melting characteristic curve of the molecular orientation and silane crosslinked ultra-high molecular weight polyethylene filament of Example 4. 5 molecular orientation and silane crosslinked ultrapolymer 1iyj? Figure 17 is a diagram showing the melting characteristic curve of the lJ ethylene filament, Figure 17 is a diagram showing the melting characteristic curve of the molecular orientation and silane crosslinked polyethylene filament of Comparative Example 6, Figure 18 is the crystallization characteristic curve of the sample in Figure 17. FIG. 19 is a diagram showing the melting characteristic curve when the sample shown in FIG. 17 is subjected to a second heating measurement.

Claims (2)

[Claims] (1) A molded body of ultra-high molecular weight polyethylene that is molecularly oriented and cross-linked with silane, and the molded body has an ultra-high melting peak determined as the main melting peak at the second temperature increase when measured with a differential scanning calorimeter in a restrained state. It has at least two crystalline melting peaks (Tp) at a temperature at least 10°C higher than the original crystalline melting temperature (Tm) of high molecular weight polyethylene, and the heat of fusion based on these crystalline melting peaks (Tp) per total heat of fusion. is 50% or more and the sum of the heat of fusion based on the high temperature side melting peak (Tp_1) in the temperature range Tm+35°C to Tm+120°C is 5% or more based on the total heat of fusion. (2) A molded product of ultra-high molecular weight polyethylene grafted with a silane compound by thermoforming a composition containing ultra-high molecular weight polyethylene with an intrinsic viscosity [η] of 5 dl/g or more, a silane compound, a radical initiator, and a diluent. A molecularly oriented and silane cross-linked ultra-high molecular weight polyethylene molded article, characterized in that the molded article is stretched, a silanol condensation catalyst is impregnated into the molded article during or after stretching, and the stretched molded article is then crosslinked by contacting with moisture. manufacturing method.