JP2019172896A - MODIFIED ETHYLENE/α-OLEFIN COPOLYMER, FORMED BODY, AND PIPE - Google Patents

Abstract

To provide an unsaturated silane graft-modified ethylene/α-olefin copolymer that can reduce the occurrence of gum deposit during the production of crosslinked pipes and can produce crosslinked pipes having a high gel fraction.SOLUTION: Provided is a modified ethylene/α-olefin copolymer, which is a modified ethylene/α-olefin copolymer obtained by graft-modifying an ethylene/α-olefin copolymer having, in an integral elution curve measured by temperature elution fractionation (TREF), an elution amount integral value at 80°C or below of 35 mass% or less, with an unsaturated silane compound, and in which, characterized, the modified ethylene/α-olefin copolymer satisfies the following (1) to (2): (1) the gel fraction is 65% by mass or more; (2) the melt flow rate (MFR) at 190°C and 2.16 kg is 0.05 g/10 min or more, 2 g/10 min or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a modified ethylene / α-olefin copolymer. The present invention also relates to a molded body and a pipe using the modified ethylene / α-olefin copolymer.

  Plastics that are superior in corrosion resistance and workability compared to metal materials are used as piping materials for water supply and hot water supply. Of these, the use of so-called silane-modified polyethylene cross-linked pipes (hereinafter referred to as cross-linked pipes) obtained by cross-linking unsaturated silane-modified polyethylene, which is particularly excellent in pressure resistance and creep resistance in a high temperature region, is the mainstream. .

  Generally, a crosslinked pipe is produced by a method of crosslinking a pipe obtained by mixing polyethylene, an organic unsaturated silane compound, an organic peroxide and a silanol condensation catalyst in the presence of moisture. For the production method, the above materials are mixed at once, and the pipe is molded, and the silane-modified polyethylene is prepared once using polyethylene, an organic unsaturated silane compound, and an organic peroxide. There is sometimes a two-stage method in which a silanol condensation catalyst is added and molded.

  In these methods, the monosil method has problems that it is difficult to adjust the conditions and the defect rate such as poor appearance is high because graft modification is also performed during melt molding. The two-stage method is an improvement of this problem. However, since a silanol condensation catalyst needs to be present during the molding process, the generation of a trace amount of a crosslinking component cannot be avoided, and as a result, the generation of eyes and the like is prevented. There was a problem of not getting.

In order to deal with these problems, Patent Document 1 and Patent Document 2 describe an unsaturated silane graft from an ethylene / α-olefin copolymer polymerized using a special single-site catalyst and controlling the comonomer amount and comonomer distribution. A method for obtaining a modified ethylene / α-olefin copolymer has been proposed. However, these methods are not general because it is necessary to obtain a special material polymerized with a special single-site catalyst.
In addition, polyethylene polymerized by a generally available single-site catalyst is usually mainly a low-density grade product. On the other hand, JIS K6769, which is a standard for crosslinked polyethylene pipes, JISPA401, which is a standard for polyethylene pipes for heating, etc., are considered based on a material density of 0.94 to 0.93 kg / m ^3. If the density is too low, the creep characteristics may be affected.

JP 2011-12208 A JP 2017-66332 A

  The present invention has been made in view of the above problems, and is capable of reducing generation of eyes when a crosslinked pipe is produced, and an unsaturated silane graft capable of producing a crosslinked pipe having a high gel fraction. It is an object of the present invention to provide a modified ethylene / α-olefin copolymer, a molded body using the same, and a crosslinked pipe.

The present inventor has intensively studied to solve the above problems. As a result, in the integral elution curve measured by temperature elution fractionation (TREF), the ethylene / α-olefin copolymer whose elution amount integral value in the specific temperature range is less than the specific amount is graft-modified with an unsaturated silane compound. It has been found that the above problem can be solved by using a modified ethylene / α-olefin copolymer having a specific melt flow rate and gel fraction, which is an ethylene / α-olefin copolymer. Invented.
That is, the present invention is as follows.

[1] Modified by graft-modifying an ethylene / α-olefin copolymer having an integrated elution amount of not more than 35% by mass at 80 ° C. or less in an integral elution curve measured by temperature elution fractionation (TREF) with an unsaturated silane compound A modified ethylene / α-olefin copolymer, wherein the modified ethylene / α-olefin copolymer satisfies the following (1) to (2):
(1) Gel fraction is 65% by mass or more (2) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min or more and 2 g / 10 min or less

[2] The modified ethylene / α-olefin copolymer according to [1], wherein the density of the ethylene / α-olefin copolymer is 925 kg / m ³ or more and 950 kg / m ³ or less.

[3] The melt flow rate (MFR) at 190 ° C. and 2.16 kg of the ethylene / α-olefin copolymer is 0.5 g / 10 min or more and 5 g / 10 min or less, [1] or [2] Modified ethylene / α-olefin copolymer described in 1.

[4] The modified ethylene / α-olefin copolymer according to any one of [1] to [3], wherein the α-olefin of the ethylene / α-olefin copolymer contains n-hexene and / or n-octene. Coalescence.

[5] Extrusion of a silane-crosslinked ethylene / α-olefin copolymer obtained by cross-linking the modified ethylene / α-olefin copolymer according to any one of [1] to [4] in the presence of a silanol condensation catalyst A molded body that is a molded body.

[6] A pipe made of the molded article according to [5].

  According to the present invention, it is possible to reduce the occurrence of spears during the production of a crosslinked pipe, and it is possible to produce a crosslinked pipe having a high gel fraction after crosslinking, excellent appearance, and excellent long-term durability. A saturated silane graft-modified ethylene / α-olefin copolymer and a pipe using the same can be provided.

2 is a photograph of a cross-linked pipe (die outlet portion) manufactured in Example 1. 4 is a photograph of a cross-linked pipe (die outlet portion) manufactured in Comparative Example 1. 6 is a photograph of a cross-linked pipe (die outlet portion) manufactured in Comparative Example 2.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, in this specification, when expressing by putting a numerical value or a physical-property value before and behind using "-", it shall use as what includes the value before and behind.

[Modified ethylene / α-olefin copolymer]
The modified ethylene / α-olefin copolymer of the present invention is an ethylene / α-olefin copolymer having an integrated elution amount of not more than 35% by mass at 80 ° C. or less in an integral elution curve measured by temperature elution fractionation (TREF). A modified ethylene / α-olefin copolymer obtained by graft-modifying a blend with an unsaturated silane compound, wherein the modified ethylene / α-olefin copolymer satisfies the following (1) to (2): .
(1) Gel fraction is 65% by mass or more (2) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min or more and 2 g / 10 min or less

<Ethylene / α-olefin copolymer>
In the present invention, as an ethylene / α-olefin copolymer subjected to graft modification with an unsaturated silane compound, in an integral elution curve measured by temperature elution fractionation (TREF), an elution amount integrated value at 80 ° C. or less (hereinafter, An ethylene / α-olefin copolymer having a mass of 35% by mass or less may be referred to as “a TREF elution component amount of 80 ° C. or lower”.

  Examples of the ethylene / α-olefin copolymer used in the present invention include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin having 3 to 20 carbon atoms to be copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene and 1-hexadecene. 1-octadecene, 1-eicocene, 3-methyl-1-butene, 4-methyl-1-pentene, 6-methyl-1-heptene and the like.

1-hexene and 1-octene are preferred as the α-olefin to be copolymerized with ethylene from the viewpoint of not only versatility but also effective in reducing the effect of the eyes when forming a pipe. The reason is as follows.
In order to obtain an ethylene / α-olefin copolymer having a predetermined density, the amount of the comonomer is adjusted, but when obtaining an ethylene / α-olefin copolymer having the same density, an α-olefin having a large number of carbon atoms is used. However, the molar amount is smaller. On the other hand, in the case of graft modification with an unsaturated silane compound, radical generation by a radical generator such as peroxide is important, but the tertiary carbon of the comonomer part is most likely to cause radical generation, and the above 80 ° C. or lower When α-olefin with a small number of carbon atoms is used as a comonomer in the TREF elution component amount, the amount of graft modification by the unsaturated silane compound becomes a component, and when these components are generated as a spear at the time of pipe forming Conceivable. For the above reasons, 1-hexene and 1-octene, which can easily adjust the density in a small amount, are preferable.

  The ethylene / α-olefin copolymer may be a copolymer of ethylene and one type of α-olefin, or may be a copolymer of ethylene and two or more types of α-olefins. Good.

  Moreover, as a catalyst used when polymerizing ethylene and α-olefin, a Ziegler-Natta catalyst or a metallocene catalyst can be used, but considering the availability of the required density range, a Ziegler-Natta catalyst A catalyst is preferred. The ethylene / α-olefin copolymer obtained by using a metallocene catalyst is usually mainly composed of a material having a low density.

  The ethylene / α-olefin copolymer used in the present invention has a TREF elution component amount of 80 ° C. or less of 35% by mass or less, preferably 30% by mass or less. The amount of TREF elution component of ethylene / α-olefin copolymer below 80 ° C is mainly the component in the α-olefin comonomer, which is eluted at a low temperature due to low crystallinity. come. These components are preferentially generated by the action of the radical generator even during graft modification with the unsaturated silane compound, resulting in a component having a high graft modification amount. It is thought to occur as an eye strain. That is, when the amount of the TREF elution component at 80 ° C. or less is more than 35% by mass, the amount of creaking on the pipe is increased. In addition, although there is no restriction | limiting in particular about the minimum of the TREF elution component amount of 80 degrees C or less of the ethylene * alpha-olefin copolymer used by this invention, Usually, it is 10 mass% or more.

  In the present invention, the TREF elution component amount of 80 ° C. or less of the ethylene / α-olefin copolymer is measured as follows.

<TREF measurement method>
A sample is dissolved in orthodichlorobenzene (containing 0.5 mg / mL BHT (dibutylhydroxytoluene), the same applies hereinafter) at 140 ° C. to obtain a solution. This was introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to 40 ° C. at a rate of 4 ° C./min, and then cooled at a rate of 1 ° C./min. To -15 ° C and hold for 20 minutes. Thereafter, orthodichlorobenzene, which is a solvent, is allowed to flow through the column at a flow rate of 1 mL / min, and components dissolved in orthodichlorobenzene at −15 ° C. are eluted in the TREF column for 10 minutes. The column is heated linearly to 140 ° C over time to obtain an elution curve. At this time, the integrated elution amount at the time of 80 ° C. is set as the TREF elution component amount of 80 ° C. or less.

Equipment used and measurement conditions are as follows.
<Devices used and measurement conditions>
(TREF part)
TREF column: 4.3 mmφ × 150 mm stainless steel column Column packing material: 100 μm surface inactive glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled by water)
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000
(Valve oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve, 4-way valve (sample injection part)
Injection method: Loop injection method Injection amount: Loop size 0.1ml
Inlet heating method: Aluminum heat block Measurement temperature: 140 ° C
(Detection unit)
Detector: Fixed wavelength infrared detector FOXBORO MIRAN 1A
Detection wavelength: 3.42 μm
High-temperature flow cell: LC-IR micro flow cell, optical path length 1.5 mm, window shape 2φ × 4 mm oval, synthetic sapphire window Measurement temperature: 140 ° C.
(Pump part)
Liquid feed pump: SSC-3461 pump manufactured by Senshu Kagaku

<Measurement conditions>
Solvent: Orthodichlorobenzene (with 0.5 mg / mL BHT)
Sample concentration: 5 mg / mL
Sample injection volume: 0.1 mL
Solvent flow rate: 1 mL / min

In the present invention, the density of the ethylene / α-olefin copolymer subjected to graft modification with the unsaturated silane compound is preferably 925 kg / m ³ or more and 950 kg / m ³ or less, more preferably 925 kg / m ³ or more and 940 kg / m. ³ or less.

The density of the ethylene / α-olefin copolymer can be adjusted mainly by the amount of other α-olefin copolymerized with ethylene, etc., and the modified ethylene / α- after graft modification with an unsaturated silane compound. Equal to olefin copolymer.
When the density of the ethylene / α-olefin copolymer exceeds 950 kg / m ³ or more, the rigidity of the resulting cross-linked pipe becomes considerably high, and the pipe workability of the pipe deteriorates. When the density of the ethylene / α-olefin copolymer is less than 925 kg / m ³ , the piping workability is improved, but the long-term durability, particularly creep resistance and heat resistance are deteriorated, and the crosslinked polyethylene pipe, the hot water supply pipe There is a high possibility that the standard will not be satisfied. Here, the density of the ethylene / α-olefin copolymer is measured by the method described in JIS K6922-2.

  The melt flow rate (MFR) at 190 ° C. and 2.16 kg of the ethylene / α-olefin copolymer subjected to graft modification with the unsaturated silane compound in the present invention is 0.5 g / 10 min or more and 5 g / 10 min or less. It is preferable that it is 1.0 g / 10 min or more and 2 g / 10 min or less.

  When the ethylene / α-olefin copolymer has a 190 ° C. and 2.16 kg MFR of less than 0.5 g / 10 min, not only the viscosity at the time of modification becomes high and the extrusion characteristics at the time of modification deteriorate, but also As a result, the MFR of the modified ethylene / α-olefin copolymer is also greatly reduced, and as a result, the pressure at the time of pipe forming is also greatly increased. For example, abnormalities in torque and the occurrence of melt fracture that deteriorates surface properties Etc. Extrudability deteriorates. On the other hand, if the MFR of the ethylene / α-olefin copolymer exceeds 5 g / 10 minutes, the MFR of the resulting modified ethylene / α-olefin copolymer also increases, and the occurrence of drawdown during pipe molding, etc. The extrusion moldability is also deteriorated.

  The melt flow rate of the ethylene / α-olefin copolymer and the modified ethylene / α-olefin copolymer of the present invention described later is measured at 190 ° C. under a load of 2.16 kg according to the method described in JIS K7210.

In the present invention, as the ethylene / α-olefin copolymer to be subjected to graft modification with an unsaturated silane compound, a commercially available product can also be used, for example, by selecting the corresponding product from DOW's Daurex series or the like. You can also. Further, only one kind of ethylene / α-olefin copolymer may be used, or two or more kinds of comonomer α-olefins having different kinds and physical properties may be mixed and used.
When two or more kinds of ethylene / α-olefin copolymers are mixed and used, the amount of TREF elution component, MFR and density of 80 ° C. or less as a mixture may be within the above range.

<Modified ethylene / α-olefin copolymer>
The modified ethylene / α-olefin copolymer of the present invention is obtained by graft-modifying the ethylene / α-olefin copolymer with an unsaturated silane compound, and hydrolyzing the ethylene / α-olefin copolymer into the ethylene / α-olefin copolymer. An olefinically unsaturated silane compound having a possible organic group can be obtained by copolymerization in the presence of a radical generator. In this reaction, the unsaturated silane compound is grafted to the ethylene / α-olefin copolymer so as to serve as a cross-linking point between the ethylene / α-olefin copolymer as a base.

Here, as the olefinically unsaturated silane compound having a hydrolyzable organic group, a silane compound represented by the following general formula (1) is preferably used.
RSiR ′ _n Y _3-n (1)
(In the formula, R represents a monovalent olefinically unsaturated hydrocarbon group, Y represents a hydrolyzable organic group, and R ′ is the same as a monovalent hydrocarbon group other than aliphatic unsaturated hydrocarbon or Y. And n represents 0, 1 or 2.)

  In general formula (1), R is preferably a vinyl group, allyl group, isopropenyl group, butenyl group, R ′ is preferably a methyl group, an ethyl group, a propyl group, a decyl group, a phenyl group, or the like, and Y is a methoxy group. An ethoxy group, a formyloxy group, an acetoxy group, a propionoxy group, and an alkyl or arylamino group are preferable.

Moreover, as a more preferable unsaturated silane compound, the compound represented by following General formula (2) is mentioned, for example.
CH ₂ = CHSi (OA) ₃ (2)
(In the formula, A represents a monovalent hydrocarbon group having 1 to 8 carbon atoms.)

Specific examples of the unsaturated silane compound represented by the general formula (1) include vinyltrimethoxysilane and vinyltriethoxysilane.
As unsaturated silane compounds,
_{CH 2 = C (CH 3)} COOC 3 H 6 Si (OA) 3
(However, A is as defined above.)
The compound represented by these can also be used preferably, and examples of such a compound include γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, and the like.

  Among these, as the unsaturated silane compound, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltriethoxysilane are preferable. These unsaturated silane compounds may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations.

  The amount of the unsaturated silane compound used for graft modification is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.00% by mass based on the total mass of the ethylene / α-olefin polymer. It is 7 mass% or more, and is 15 mass% or less normally, Preferably it is 10 mass% or less, More preferably, it is 7 mass% or less, More preferably, it is 4 mass% or less. If the amount of the unsaturated silane compound added is too small, sufficient grafting tends to be difficult, and if it is too much, it tends to cause eye strain and is not economical. Here, the addition amount of the unsaturated silane compound has the same meaning as the unit derived from the unsaturated silane compound in the modified ethylene / α-olefin copolymer.

  Examples of radical generators used at the time of graft modification include various organic peroxides and peresters having a strong polymerization initiating action, such as dicumyl peroxide, α, α′-bis (t-butylperoxydiisopropyl) benzene, Di-t-butyl peroxide, t-butyl cumyl peroxide, di-benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butyl peroxypivalate, di -T-butyl peroxide, t-butyl peroxy-2-ethylhexanoate, etc. are mentioned. Among these, dicumyl peroxide, benzoyl peroxide, and di-t-butyl peroxide are preferable. These radical generators may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations.

  The amount of radical generator added must be adjusted so that the MFR of the resulting modified ethylene / α-olefin copolymer finally falls within the following MFR range. Based on the total mass of the copolymer, it is usually 0.01% by mass or more, preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and usually 0.5% by mass or less, preferably It is 0.4 mass% or less, More preferably, it is 0.2 mass% or less. If the amount of the radical generator used is too small, sufficient grafting reaction tends to be difficult, and if it is too much, the MFR of the resulting modified ethylene / α-olefin copolymer is lowered and the extrusion processability is lowered. However, the molding surface tends to deteriorate.

The melt flow rate (MFR) at 190 ° C. and 2.16 kg of the modified ethylene / α-olefin copolymer of the present invention is 0.05 g / 10 min or more and 2 g / 10 min or less. This MFR is preferably 0.1 g / 10 min or more, preferably 1 g / 10 min or less.
If the MFR of the modified ethylene / α-olefin copolymer is lower than 0.05 g / 10 min, the pressure at the time of pipe forming will increase significantly, for example, the occurrence of torque abnormality or melt fracture that deteriorates the surface properties, etc. Extrudability deteriorates. On the other hand, when the MFR of the modified ethylene / α-olefin copolymer exceeds 2 g / 10 minutes, the extrusion moldability is also deteriorated due to the occurrence of drawdown during pipe molding.

  Further, the modified ethylene / α-olefin copolymer of the present invention is required to have a gel fraction of 65% by mass or more. This is generally defined in JIS K6769, which is a standard for cross-linked polyethylene pipes, and in JXPA 401, which is a standard for heating polyethylene pipes. Here, the gel fraction serves as an index indicating the degree of cross-linking of the resin. If the gel fraction is large, the degree of cross-linking is high. Conversely, if the gel fraction is small, the degree of cross-linking is low. When the degree of cross-linking of the modified ethylene / α-olefin copolymer is lower than 65% by mass, the heat resistance and creep characteristics of the finally obtained product are deteriorated. From this viewpoint, the gel fraction of the modified ethylene / α-olefin copolymer of the present invention is preferably 68% by mass or more. On the other hand, since it is difficult in the present technology to completely crosslink all the molecules, the upper limit of the gel fraction of the modified ethylene / α-olefin copolymer of the present invention is usually 90% by mass or less.

  The gel fraction measurement method defined in JIS K6769 or JISPA401 is measured using a pipe that has been subjected to crosslinking treatment in the pipe state after actual pipe forming, but for the sake of simplicity in the present invention. The gel fraction of the modified ethylene / α-olefin copolymer is measured by the following method.

<Method for measuring gel fraction of modified ethylene / α-olefin copolymer>
That is, 0.05% by mass of dioctyltin laurate was added to the modified ethylene / α-olefin copolymer (actually MFR: 1 g / 10 min, density 920 kg / m ³ linear low density polyethylene with dioctyltin laurylate. A master batch to which 1% by mass of a rate was added was added), and after melt-kneading, a sheet extruded to a thickness of 0.5 mm at 210 ° C. was cut into 1 mm square using a sample obtained by crosslinking in 80 ° C. warm water for 24 hours. About 0.5 g of the sample (sample weight: G1 (g)) was refluxed in xylene at 120 ° C. for 8 hours in a 200-mesh wire mesh, and then the boiling xylene-insoluble matter remaining on the wire mesh was in a vacuum of 10 Torr. The sample is dried at 80 ° C. for 8 hours, and the weight thereof is weighed (the weight of the boiled xylene-insoluble matter is G2 (g)).
Gel fraction (%) = G2 (g) ÷ G1 (g) × 100

  Further, the modified ethylene / α-olefin copolymer of the present invention has an appropriate content of units derived from the unsaturated silane compound, and the gel fraction and MFR as a mixture are within the above-mentioned prescribed ranges. A blend of two or more kinds of modified ethylene / α-olefin copolymers, or a blend of a modified ethylene / α-olefin copolymer and an unmodified ethylene / α-olefin copolymer. Also good.

[Silanol condensation catalyst]
The modified ethylene / α-olefin copolymer of the present invention is extruded as a silane-crosslinked ethylene / α-olefin copolymer obtained by crosslinking reaction in the presence of a silanol condensation catalyst.

  Examples of the silanol condensation catalyst include tin catalysts such as dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate and dioctyltin dilaurate; lead catalysts such as lead naphthenate and lead stearate; zinc caprylate, Zinc catalysts such as zinc stearate; Cobalt catalysts such as cobalt naphthenate; Titanium catalysts such as tetrabutyl ester; Cadmium catalysts such as cadmium stearate; Organics such as alkaline earth metal catalysts such as barium stearate and calcium stearate A metal catalyst is mentioned. Of these, tin catalysts are preferred. These silanol condensation catalysts may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations.

  The addition amount of the silanol condensation catalyst is usually 0.01% by mass or more, preferably 0.02% by mass or more, more preferably based on the total mass of the modified ethylene / α-olefin copolymer to which the silanol condensation catalyst is added. It is 0.05 mass% or more, and is 5 mass% or less normally, Preferably it is 3 mass% or less, More preferably, it is 2 mass% or less. If the amount of the silanol condensation catalyst added is too small, sufficient crosslinking reaction will not proceed, and if it is too much, it will be disadvantageous in terms of cost.

  In addition, it is easy to add a silanol condensation catalyst generally in a masterbatch format. The master batch of the silanol condensation catalyst is produced, for example, by adding and kneading the silanol condensation catalyst to one or more of polyolefins such as ethylene homopolymer (polyethylene) and ethylene / α-olefin copolymer. be able to.

  When the silanol condensation catalyst is used as a master batch in which a silanol condensation catalyst is blended with polyolefin, the content of the silanol condensation catalyst in the master batch is not particularly limited, but is usually about 0.1 to 5.0% by mass. It is preferable.

  If necessary, other miscible thermoplastic resins, stabilizers, lubricants, fillers, colorants, foaming agents, and other auxiliary materials can be added to the silanol condensation catalyst-containing masterbatch. These additives may be those commonly used and known per se. Further, as a third component, it is also possible to add these additives together with a silanol condensation catalyst to the modified ethylene / α-olefin copolymer of the present invention.

[Bridged pipe]
The cross-linked pipe using the modified ethylene / α-olefin copolymer of the present invention is formed by melt-kneading and extruding the raw material with a molding machine provided with a cylindrical die in an extruder.

  During the main molding, the eyes are accumulated near the die exit, and when the amount of accumulation increases, it causes defective appearance of the pipe and foreign matters. In addition, cleaning is necessary as a countermeasure, but by carrying out the cleaning, the yield during that time deteriorates, and if the accumulation of the center part of the die is significant, the continuous extrusion of the pipe must be cut once, the yield, As a result, the cost is greatly affected, but such a problem is solved by using the modified ethylene / α-olefin copolymer of the present invention.

The resulting pipe crosslinks silane groups in the presence of warm water or steam. The crosslinking conditions are determined in consideration of the finally obtained gel fraction.
The cross-linked pipe using the modified ethylene / α-olefin copolymer of the present invention is a high-quality pipe with reduced eyes and excellent appearance and long-term durability. According to the present invention, such a cross-linked pipe is used. Can be manufactured with good yield.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated more concretely using an Example, this invention is not limited by a following example, unless the summary is exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiments of the present invention, and preferred ranges are the above-described upper limit or lower limit values and the following values: It may be a range defined by a combination of values of the examples or values of the examples.

[Production Example 1]
DOW DOULEX 2042G (ethylene / n-octene copolymer, MFR: 1.0 g / 10 min, density: 930 kg / m ³ ) and QAMAR FC18N (ethylene / n-butene copolymer, MFR: 2 g / 10 min, density: 920 kg / m ³ ) was mixed at a mass ratio of 70:30 to obtain an ethylene / α-olefin copolymer mixture 1.

Table 1 shows the density, MFR, and TREF elution component amount of 80 ° C. or less measured for the ethylene / α-olefin copolymer mixture 1 by the following method.
MFR: JIS K7210, 190 ° C, 2.16 kg
Density: JIS K6922-2
TREF elution component amount of 80 ° C. or lower: the above-mentioned method For ethylene / α-olefin copolymer mixture 1 and ethylene / α-olefin copolymer mixtures 2 and 3 described later, di-t-butyl peroxide and vinyl tri The mixture containing no methoxysilane was mixed at 210 ° C. with a 15 mm twin-screw extruder, and the obtained sample was used for measurement.

After adding and mixing 0.04 mass part of di-t-butyl peroxide and 2 mass parts of vinyltrimethoxysilane with respect to 100 mass parts of this ethylene / α-olefin copolymer mixture 1, biaxial A modified ethylene / α-olefin copolymer 1 was obtained by kneading and extrusion at 230 ° C. in an extruder.
The MFR (JIS K7210, 190 ° C., 2.16 kg) of the obtained modified ethylene / α-olefin copolymer 1 was measured. The results are shown in Table 2.
Further, the gel fraction of the modified ethylene / α-olefin copolymer 1 was measured by the method described above, and the results are shown in Table 2.

[Production Example 2]
FD18N (ethylene / butene copolymer, MFR: 2.0 g / 10 min, density: 920 kg / m ³ ) manufactured by QAMAR and HY430 (ethylene / butene copolymer, MFR: 0.8 g / 10) manufactured by Nippon Polyethylene The modified ethylene / α-olefin copolymer was prepared in the same manner as in Production Example 1 except that the ethylene / α-olefin copolymer mixture 2 was mixed at a mass ratio of 75:25 (min, density: 956 kg / m ³ ). A polymer 2 was obtained. Table 1 shows the density, MFR, and TREF elution component amount of 80 ° C. or less of the ethylene / α-olefin copolymer mixture 2. Table 2 shows the MFR and gel fraction of the modified ethylene / α-olefin copolymer 2 obtained.

[Production Example 3]
FD18N (ethylene / butene copolymer, MFR: 2.0 g / 10 min, density: 920 kg / m ³ ) manufactured by QAMAR and HY430 (ethylene / butene copolymer, MFR: 0.8 g / 10) manufactured by Nippon Polyethylene Ethylene / α-olefin copolymer in the same manner as in Production Example 1 except that the ethylene / α-olefin copolymer mixture 3 was mixed at a mass ratio of 70:30 by weight, density: 956 kg / m ³ ). A coalescence mixture 3 was obtained. Table 1 shows the density, MFR, and TREF elution component amount of 80 ° C. or less of the ethylene / α-olefin copolymer mixture 3. Further, Table 2 shows the MFR and gel fraction of the obtained modified ethylene / α-olefin copolymer 3.

[Example 1]
Silanol condensation catalyst master batch (1% by weight tin catalyst (dioctyltin dilaurate) -containing linear low density polyethylene (MFR: 4 g / 10 min, density) with respect to 100 parts by mass of the modified ethylene / α-olefin copolymer 1 : 900 kg / m ³ ) Master batch) 5 parts by mass were dry blended and supplied to a 50 mm single screw extruder equipped with a die for a pipe having a die diameter of 8 mm and a core diameter of 5 mm to prepare a crosslinked pipe. Extrusion was started, and after purging for 15 minutes, the die outlet was cleaned, and the state of the eye deposit accumulated at the die outlet when continuously extruded for 45 minutes was confirmed and evaluated according to the following criteria. The results are shown in Table 2. Moreover, the external appearance photograph of the bridge pipe near the die after 45 minutes is shown in FIG.

<Eye Jani Evaluation Criteria>
◯: There is almost no eyes, and it has a beautiful appearance.
(Triangle | delta): There are few eyes | cracks and it is slightly inferior to an external appearance.
X: There are very many eyes and the appearance is remarkably inferior.

[Comparative Examples 1-2]
Other than using modified ethylene / α-olefin copolymer 2 (Comparative Example 1) or modified ethylene / α-olefin copolymer 3 (Comparative Example 2) instead of modified ethylene / α-olefin copolymer 1 In the same manner as in Example 1, a cross-linked pipe was prepared, and the accumulation state of the eyes was evaluated in the same manner.
The results are shown in Table 2.
Moreover, the external appearance photograph of the die part at the time of shaping | molding of the bridge | crosslinking pipe | tube near the die | dies 45 minutes after in Comparative Examples 1 and 2 is shown to FIG.

  From the above results, according to the modified ethylene / α-olefin copolymer of the present invention, it is possible to reduce the creaking at the time of production of the crosslinked pipe, the gel fraction is high, the appearance is excellent, and the long-term durability is achieved. It can be seen that excellent cross-linked pipes can be produced.

Claims (6)

In an integrated elution curve measured by temperature elution fractionation (TREF), an ethylene / α-olefin copolymer having an integrated elution amount of not more than 35% by mass at 80 ° C. or lower is graft-modified with an unsaturated silane compound. -An olefin copolymer, wherein the modified ethylene / α-olefin copolymer satisfies the following (1) to (2):
(1) Gel fraction is 65% by mass or more (2) Melt flow rate (MFR) at 190 ° C. and 2.16 kg is 0.05 g / 10 min or more and 2 g / 10 min or less The modified ethylene / α-olefin copolymer according to claim 1, wherein the ethylene / α-olefin copolymer has a density of 925 kg / m ³ or more and 950 kg / m ³ or less.   The modified ethylene according to claim 1 or 2, wherein a melt flow rate (MFR) at 190 ° C and 2.16 kg of the ethylene / α-olefin copolymer is 0.5 g / 10 min or more and 5 g / 10 min or less. Α-olefin copolymer.   The modified ethylene / α-olefin copolymer according to claim 1, wherein the α-olefin of the ethylene / α-olefin copolymer contains n-hexene and / or n-octene.   A molded product, which is an extrusion molding of a silane-crosslinked ethylene / α-olefin copolymer obtained by crosslinking the modified ethylene / α-olefin copolymer according to any one of claims 1 to 4 in the presence of a silanol condensation catalyst. .   A pipe comprising the molded body according to claim 5.