JP5074673B2 - Method for molding fiber reinforced thermoplastic resin - Google Patents

Description

  The present invention relates to a method for injection molding of a fiber reinforced thermoplastic resin, and more specifically, impregnating a reinforcing fiber in a mold with a bifunctional compound that is linearly polymerized, and polymerizing the bifunctional compound in the mold as it is. Relates to a method for molding a fiber-reinforced thermoplastic resin.

  Fiber Reinforced Thermoplastic Resin (FRTP) is a composite material in which the strength is improved by reinforcing a thermoplastic resin with a reinforcing fiber, which is difficult with a fiber reinforced thermosetting resin reinforced with a reinforcing fiber. In recent years, it has been used for various purposes because it can be reused, recycled and secondary processed. Such FRTP is generally formed and manufactured by a method of kneading a thermoplastic resin and reinforcing fibers (see, for example, Non-Patent Document 1).

  However, the following problems are known when kneading a thermoplastic resin and reinforcing fibers. That is, in order to impregnate the reinforcing fiber with a high molecular weight thermoplastic resin, it is necessary to melt the thermoplastic resin at high pressure and high temperature to ensure fluidity and wettability with the fiber. As a result, the reinforcing fibers such as glass fibers are damaged by the high pressure and high temperature, and the reinforcing fibers in the composite material become short fibers, and the strength of the fiber itself decreases due to the damage, and this composite material is finally used. The strength characteristics of the molded FRTP are reduced. Further, since the thermoplastic resin has a high molecular weight, the reinforcing fiber is not sufficiently impregnated with the thermoplastic resin, and a void is generated at the interface between the thermoplastic resin and the reinforcing fiber. Further, there is a disadvantage that the thermoplastic resin is decomposed or deteriorated by being held at a high temperature for a long time. Furthermore, much larger molding energy is required as compared with the production of a composite of a thermosetting resin and reinforcing fibers. In addition, since the reinforcing fibers are impregnated at the stage of the thermoplastic resin that has already been polymerized, there is no chemical reaction with the coupling agent of the reinforcing fibers and the interface between the reinforcing fibers and the thermoplastic resin. The chemical bonding does not occur, and the composite efficiency is greatly reduced.

  On the other hand, the injection molding method is a method in which a liquid resin is injected into a space inside a molding die in which reinforcing fibers are arranged in advance, the resin is cured, and then demolded to obtain a molded body. Or it is applicable to manufacture of the molding of various shapes including a molding of a complicated shape, and when forming a fiber reinforced composite material, it is known as a method with high reproducibility of accuracy. In the injection molding method, molding is performed in a state in which the reinforcing fiber is impregnated in the mold. Therefore, it is desirable that the injection resin has a low viscosity at the time of injection, and that the molded body can be demolded by solidifying in the mold. Therefore, thermosetting resins such as unsaturated polyester resins, epoxy resins, vinyl ester resins, and phenol resins have been conventionally used. This is because the thermosetting resin is in a very low-viscosity monomer state when injected into the mold, and can be polymerized and cured to change into a polymer state after impregnation with the fiber.

  A method for producing a fiber-reinforced thermoplastic by mixing a reactive compound with a reinforcing fiber and then polymerizing is known (for example, see Patent Document 1). In this technique, first, a prepreg impregnated with a reactive compound and dried is manufactured, and thereafter, this is hot-pressed to perform a polymerization reaction, thereby manufacturing a molded body. In addition, a method for producing a polylactam composite material by impregnating a reinforcing lactam melt into a reinforcing fiber is also known (see, for example, Patent Documents 2 and 3). However, lactams are inherently ring-opening polymerized, and unreacted monomers are likely to remain due to the characteristics of the reaction mechanism, and only deteriorate the water resistance, solvent resistance, and chemical resistance of the molded product. In addition, the molded body is deteriorated with time due to the desorption of the residual monomer with time. Further, it is difficult to increase the molecular weight in a short time, and the molding time tends to be long. Furthermore, since the technique of Patent Document 3 causes caprolactam detachment, it is not preferable for injection molding.

Satoshi Hayashi “Composite Materials Engineering” Nisshin Gijutsu Publishing Co., Ltd. (1971) International Publication No. 2004/060981 Pamphlet JP-A-9-208712 JP-A-5-178985

  The object of the present invention is applicable to the manufacture of molded products of various shapes, including molded products of large or complex shapes, in view of the above-mentioned current situation, and voids at the interface between the thermoplastic resin and the reinforcing fibers Provided is a fiber reinforced thermoplastic resin injection molding method that can suppress generation to a sufficient level and can be molded without the need for high temperature and high pressure, and a fiber reinforced plastic molded by the method. There is to do.

  In the present invention, the compound (A) having two epoxy groups in one molecule and the compound (B) having two phenolic hydroxyl groups in one molecule are placed in a mold in which reinforcing fibers are arranged in advance. Injecting and mixing with the reinforcing fiber (I), and the compound (A) and the compound (B) mixed with the reinforcing fiber are combined with the compound (A) in the mold. Using a polymerization catalyst and a reaction retarder for the compound (B), polymerization is performed in a linear form by polyaddition reaction, and a thermoplastic resin formed by polymerizing the compound (A) and the compound (B) is formed. And a step (II) of forming a fiber-reinforced thermoplastic resin.

According to the molding method of the present invention, with the above-described configuration, the low-viscosity compound (A) and compound (B) (in the present specification, the reactive compound and the other compound are added to the reinforcing fiber previously placed in the mold. ) And then into a polymer, it can be molded at low pressure, and no large press or injection device is required. For this reason, it is possible to form a large or complex shaped molded article with low energy, and economically and environmentally compared to the conventional injection molding and thermoplastic resin molding methods using large presses, There is a great advantage. That is, in the present invention, at the time when the epoxy compound is mixed and impregnated into the reinforcing fiber inside the injection mold, the state of the low-viscosity compound (monomer, etc.) is maintained, and the mixing and impregnation of the fiber is sufficiently completed By selecting reactive compounds (including epoxy compounds) so that only the polyaddition reaction proceeds linearly preferentially and does not substantially involve three-dimensional crosslinking, reinforcing fibers can be obtained with very low energy. And epoxy resin can be composited, and a high-quality thermoplastic composite material having a high composite level can be obtained.
In addition, when compounded with reinforcing fibers, the reactive compound has a low viscosity, so that the wettability with the reinforcing fibers is extremely good, and no voids remain between the fiber bundles. Is obtained. For this reason, it becomes possible to easily and easily produce moldings having various complicated shapes in which generation of voids becomes a problem.

In addition, the low molecular weight thermoplastic resin and the reinforcing fiber are in a wet state, and then the polymerization of the resin proceeds while the reinforcing fiber and the thermoplastic resin are in a wet state. The chemical reaction with the agent is sufficiently performed, and a strong bond is possible.
Furthermore, in the present invention, by mixing the thermoplastic resin with the reinforcing fiber in a low molecular state, there is no decrease in strength due to fiber damage as in the conventional FRTP, and the reaction occurs when the fiber and the resin are wet. Advancing chemical bonds at the interface become stronger.
In the molding method of the present invention, a general injection molding method (RTM method, VARTM method, RTMV method, RRIM method, etc.) of FRP using a thermosetting resin that undergoes a three-dimensional crosslinking reaction can be applied.

  In the present invention, as described later, it is strengthened in advance in the mold of a mold (usually formed of a pair of separable molds, and a space into which a molding material can be introduced is formed by the pair of molds). After disposing the fibers and closing the mold, the compound (A) and the compound (B), which form a thermoplastic epoxy resin by polymerization reaction in the mold from the injection holes provided at appropriate positions, are subjected to a relatively low pressure. The reinforcing fiber is mixed and impregnated in the state where the reactive compound is not substantially polymerized (step (I)), and then the reinforcing fiber is mixed and impregnated in the mold as it is. A polymerization reaction of the compound (A) and the compound (B) is caused to obtain a thermoplastic resin in which reinforcing fibers are arranged (step (II)).

  In the said process (I), when inject | pouring the said compound (A) and compound (B) into a type | mold, it is preferable that it is a molten state, respectively. However, the compound (A) and the compound (B) must be in a molten state at least when polymerized in the step (II), and can be sufficiently impregnated into the reinforcing fiber at that time, so that injection is possible. As long as it can be mixed with the reinforcing fiber, it is not necessarily in the molten state in the step (I).

  Moreover, it is possible to obtain a molded product with a higher composite level by reducing the pressure in the mold and injecting the resin. Hereinafter, steps will be described in order. In the present specification, the thermoplastic epoxy resin refers to a linear polymer or copolymer of an epoxy compound or an epoxy compound and a compound capable of reacting with the epoxy compound.

  As the compound (A) having two epoxy groups in one molecule, for example, it has one benzene ring such as catechol diglycidyl ether, resorcin diglycidyl ether, t-butylhydroquinone diglycidyl ether, phthalic acid diglycidyl ether, etc. Mononuclear aromatic diepoxy compounds, dimethylolcyclohexanediglycidyl ether, 3,4-epoxycyclohexenylmethyl-3,4-epoxycyclohexenylcarboxylate, alicyclic epoxy compounds such as limonene dioxide, bis (4 -Hydroxyphenyl) methane diglycidyl ether, 1,1-bis (4-hydroxyphenyl) ethane diglycidyl ether, 2,2-bis (4-hydroxyphenyl) propane diglycidyl ether and the like bisphenol type epoxy compounds and Oligomer mixture (bisphenol type epoxy resin) in which these are partially condensed, 3,3 ', 5,5'-tetramethylbis (4-hydroxyphenyl) methane diglycidyl ether, 3,3', 5,5'-tetramethyl Examples thereof include bis (4-hydroxyphenyl) ether diglycidyl ether. Hydroquinone diglycidyl ether, methylhydroquinone diglycidyl ether, 2,5-di-t-butylhydroquinone diglycidyl ether, biphenyl type or tetramethylbiphenyl type epoxy resins, bisphenol fluorene type or biscresol fluorene type epoxy resin alone In an epoxy resin that exhibits crystallinity and melts at a temperature of 200 ° C. or lower even when it is solid at room temperature, it can be used.

  Examples of the compound (B) having two phenolic hydroxyl groups in one molecule include one benzene ring such as catechol, resorcin, hydroquinone, methylhydroquinone, t-butylhydroquinone, and 2,5-di-t-butylhydroquinone. Mononuclear aromatic dihydroxy compounds having 2, 2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) ethane (bisphenol AD), bis (hydroxyphenyl) Bifunctional phenols introduced with allyl groups such as bisphenols such as methane (bisphenol F), bisphenol fluorene and biscresol fluorene, compounds having a condensed ring such as dihydroxynaphthalene, diallyl resorcin, diallyl bisphenol A and triallyl dihydroxy biphenyl And the like.

  A compound having a fluorene skeleton can be used as at least a part of the compound (A) and / or at least a part of the compound (B). In this case, the melting temperature of the polymerized resin is adjusted to achieve high-temperature meltability. It can be set as resin.

  The compounding amount of the compound (A) and the compound (B) is preferably 0.9 to 1.1 mol, more preferably 0.95 to 1.05 mol with respect to 1 mol of the compound (A). More preferred.

  The reinforcing fiber used in the present invention has an aspect ratio of 1000 or more (more preferably 5000 or more), and a substrate having the form of a fiber braid (woven fabric, knitted fabric, braid), chopped strand mat, or continuous fiber mat. It is preferable that By using the base material as described above, the degree of reinforcement of the thermoplastic resin can be improved, and a fiber-reinforced thermoplastic resin exhibiting excellent mechanical properties can be molded and manufactured.

  As the reinforcing fibers, for example, organic fibers such as aramid fibers, and inorganic fibers such as glass fibers and carbon fibers can be used, but it is preferable to use carbon fibers and glass fibers.

  As glass fiber, glass fiber monofilament, glass fiber strand, glass fiber roving, glass fiber yarn and other long fibers; glass fiber chopped strands, glass fiber chopped fibers such as cut pieces of glass fiber roving, etc. can be used. Fiber milled fiber or the like may be included.

  Moreover, glass fiber braids, such as a glass fiber fabric, a glass fiber braid, a glass fiber braid, and a glass fiber nonwoven fabric, are also applicable. In addition, the glass fiber may have been subjected to a surface treatment with a surface treatment agent such as an epoxy silane coupling agent or an acrylic silane coupling agent.

  As the glass fiber, a cut product of glass fiber roving or a glass fiber fabric is preferable, and the cut product of glass fiber roving is a glass fiber bundle in which 100 to 2000 glass fiber monofilaments having a diameter of 3 to 100 μm are bundled. It is further bundled, and the fiber length is preferably 10 cm or more (more preferably 50 cm or more).

  As the glass fiber fabric, a glass fiber bundle of 5 to 500 TEX (preferably 22 to 68 TEX) is used as warp and weft, and the weave density is 16 to 64/25 mm in the warp direction and 15 to 60/25 mm in the weft direction. It is preferable that it is woven so that it becomes. And as for the glass fiber bundle which comprises a glass fiber fabric, the thing by which 50-1200 glass fiber monofilaments (filament diameter is preferable 3-23 micrometers) is bundled is preferable.

  As a glass composition of the said glass fiber, E glass, S glass, C glass etc. are mentioned, for example, E glass is especially preferable. Further, the cross section of the glass fiber monofilament may be circular or flat such as elliptical.

  There are three types of carbon fiber: “pitch-type” made from coal tar pitch or petroleum pitch, “PAN-type” made from polyacrylonitrile, and “rayon-type” made from cellulose fiber. Even fibers can be used in the present invention.

  In the injection molding method of the present invention, prior to the injection, mixing, and impregnation of the resin, the fiber reinforcing material having a predetermined mixing ratio and a predetermined shape is arranged in the mold in a uniform and set direction. This step is a reinforcing fiber shaping step. In this case, the reinforcing material can be arranged in a two-dimensional or three-dimensional manner. In addition, in the injection molding method, a preform in which the reinforcing material is preliminarily processed may be used by preceding the shaping of the reinforcing material.

  The blending ratio of the reinforcing fibers in the molded body may vary depending on the type of fiber. For example, in the case of glass fibers, the reinforcing fibers are preferably 10 to 75% by weight, and preferably 25 to 70% by weight. Is more preferable. If the amount of reinforcing fiber is less than 10% by weight, the physical properties of the molded product tend to be low or warpage and undulation tend to increase. If the amount exceeds 75% by weight, the fiber tends to become unimpregnated with resin. is there. For other types of reinforcing fibers, the blending known to those skilled in the art can be easily used while referring to the blending amount.

  As the injection pressure, the raw material mixture is preferably a pressure that can be injected, preferably in a molten state, and depends on whether or not the inside of the mold is decompressed. An injection pressure of about 0.01 MPa to 1 MPa can be used, and about 10 KPa to 100 KPa can be used for injection under reduced pressure.

  The injection mold is not particularly limited as long as the molded body can be obtained through resin injection, molding, and demolding of the molded body, and usually consists of a pair of separable molds. A space into which the molding material can be introduced is formed. In the present invention, reinforcing fibers are arranged in advance in the interior, and the mold is closed to prepare for resin injection. The mold can be high-rigidity or low-rigidity, and the high-rigidity can be used under conditions that generate internal pressure. The low rigidity can be used for injection and molding under reduced pressure. For example, it has a first mold and a second mold, and either of the first mold and the second mold is a resin ( For example, a mold made of a film of PVA, nylon, etc.) or rubber is injected with compound (A) and compound (B) in a state where the inside of the mold surrounded by the first mold and the second mold is decompressed. To do. The injection mold has a temperature control function for heating and cooling in order to allow the polymerization of the compound (A) and the compound (B) to proceed and to cool the molded product after polymerization to facilitate demolding. It is desirable that In addition, a general injection molding method (RTM method, VARTM method, RTMV method, RRIM method, etc.) of FRP using a thermosetting resin can be applied.

  The compound (A) and the compound (B) can be linearly polymerized by a polyaddition reaction as exemplified below. The linear polymerization can be confirmed by the solubility in a solvent and the heat melting property. In addition, as long as the objective of this invention is not inhibited, it does not exclude that a crosslinked structure exists in part.

  A polymerization catalyst can be used for this reaction. Examples of the polymerization catalyst include phosphorus catalysts, 1,2-alkylenebenzimidazole (TBZ), and 2-aryl-4,5-diphenylimidazole (NPZ). These are used alone or in combination of two or more. Phosphorus catalysts are preferred because they improve reflowability.

  Examples of the phosphorus catalyst include dicyclohexylphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, cyclohexyldiphenylphosphine, triphenylphosphine, triphenylphosphine-triphenylborane complex, tri -M-tolylphosphine-triphenylborane complex etc. are mentioned. Among these, tri-o-tolylphosphine and tri-m-tolylphosphine-triphenylborane complex are preferable.

  The amount of the polymerization catalyst used is usually 0.1 to 10 parts by weight, more preferably 0.4 to 6 parts by weight, and particularly 1 to 5 parts by weight with respect to 100 parts by weight of the compound (A). However, it is preferable from the viewpoint of excellent balance between short-time polymerization and pot life.

  When the mixture of the compound (A), the compound (B) and the polymerization catalyst is in a liquid state at room temperature, heating is not required in the impregnation step into the reinforcing fiber, or the thickening accompanying the start of polymerization of the mixture is remarkably caused. It is preferable from the point that the viscosity is sufficiently lowered and impregnation into the reinforcing fiber is facilitated by heating to a certain extent.

  Further, even when the compound (A) and the compound (B) are each solid alone, the viscosity when the mixture of the compound (A), the compound (B) and the polymerization catalyst is heated at a temperature of 200 ° C. or less. Can be applied to the present invention by using a two-component mixing apparatus equipped with a tank capable of heating and a static mixer.

  A reaction retarder can also be used in the present invention. In the two-component mixing and impregnation process for reinforcing fibers, the resin is uniformly liquefied and the viscosity is reduced as much as possible, so it is often heated, so polymerization is performed before the resin is impregnated into the reinforcing fibers. The reaction is initiated, the viscosity increases, and poor impregnation can occur. In order to prevent this, a reaction retarding agent that delays the reaction during heating for decreasing the viscosity and does not inhibit the reaction during the polymerization reaction after the impregnation is suitably used. As such a retarder, trialkyl borates such as tri-n-butyl borate, tri-n-octyl borate and tri-n-dodecyl borate, and triaryl borates such as triphenyl borate can be used. These are used alone or in combination of two or more. Among these, tri-n-octyl borate is preferable because it is liquid at room temperature and has excellent miscibility and significantly delays the reaction at 80 ° C. or lower.

  The amount of the reaction retarder used is such that the boron atom of the boric acid ester is 0.1 to 2.0 mol, more preferably 0.5 to 1.2 mol, especially 1 mol of the phosphorus atom of the phosphorus catalyst. Is preferably from 0.7 to 1.0 mol because the impregnation time is long and the polymerization is possible for a short time.

  In the present invention, a filler made of inorganic powder such as organic powder or aluminum hydroxide, a known flame retardant, or the like may be added as an optional additive component. Moreover, you may use a solvent in the range which does not inhibit the objective of this invention, for the objective of viscosity adjustment etc., for example. Examples of the solvent include ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone, and ethers such as methyl cellosolve and ethylene glycol dibutyl ether. Among these, acetone is preferable because it can easily fly during polymerization. The amount used is preferably 0.1 to 15 parts by weight, more preferably 4 to 8 parts by weight, based on 100 parts by weight of the resin component. When the amount is too small, phenols are precipitated, and when the amount is too large, deterioration of physical properties due to the solvent remaining in the resin after polymerization becomes large.

  The polymerization catalyst, reaction retarder, additive and the like can be added to either or both of the reactive compounds before being injected into the mold in advance.

  In the polymerization reaction in the molding method of the present invention, since the impregnation and polymerization proceed in the mold after the resin is injected, the polymerization conditions are set near the set temperature of the mold. The mold temperature is generally from about 80 ° C. by hot water heating or the like to about 200 ° C. by steam heating, electric heater or the like. Depending on the type of reactive compound, polymerization catalyst, and reaction retarder used, the temperature range for causing the polymerization reaction is different. Usually, the polymerization temperature is 100 to 200 ° C., and the polymerization time is 3 to 20 minutes. Degree. Moreover, it is preferable that the time when the polymerization starts after the resin is injected into the mold is longer than the filling time of the injected resin into the mold. In this case, the standard for starting the polymerization is the standard time for the resin viscosity at the time of injection to double. That is, it is desirable that the injection of all the resins has been completed while the viscosity of the resin has doubled since the injection of the resin.

  When the fiber-reinforced thermoplastic epoxy resin molded product obtained in the polymerization reaction step (II) has a Tg near the polymerization temperature, it is demolded after the cooling step or demolded immediately after the completion of the polymerization. In this case, it is desirable to fix it with a shape-holding jig or the like that approximates the shape of the molded product and hold it until the temperature of the molded product decreases.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, the following description is only for description and the present invention is not limited to these Examples.

Example 1
First, raw materials shown in Table 1 below were mixed in parts by weight shown in the same table to obtain a mixture of reactive compounds (hereinafter referred to as base C). The obtained mixture did not undergo a polymerization reaction when the mixture was prepared and stored at room temperature. The meanings of the abbreviations in Table 1 are as follows.
AER260 Asahi Kasei Co., Ltd. bisphenol type liquid epoxy resin (epoxy equivalent: 190 g / eq)
BPA-M Mitsui Chemicals bisphenol A (hydroxyl equivalent: 114 g / eq)
TOTP Tri-o-tolylphosphine manufactured by Hokuko Chemical Co., Ltd. (molecular weight: 304)
Tri-n-octyl borate manufactured by Tokyo Chemical Industry Co., Ltd. (molecular weight: 398)

  A carbon fiber fabric (plain weave carbon cloth, C06343 manufactured by Toray Industries, Inc., thickness: 0) is placed inside the mold 13 that is heated and held uniformly at 120 ° C. (male and female clearance t = 4.0 mm). 18 sheets of .25 mm, weight: 195 g / m2) were set and clamped. The base C obtained above was filled in the heated resin tank 01 shown in FIG. The warming resin tank 03 was filled only with BPA-M and kept at 160 ° C., which exceeded the melting point of BPA-M (155 ° C.), so that it was completely melted. The heated base C from the warming resin tank 01 and the BPA-M from the warming resin tank 03 were adjusted with the flow meters 09 and 10 so that the blending ratio was 107.93: 60, and the gear pump 04, In 05, the resin was fed into the static mixer 11 through the resin pipes 06 and 08, and the base C and BPA-M were mixed and then injected into the mold from the injection port 12 of the mold 13. The injection pressure was 0.1 MPa and the injection was completed in about 5 minutes. After the completion of the injection, the mold temperature was raised to 160 ° C. and held at 160 ° C. for 10 minutes, and then the cooling process was started. The cooling was performed by water cooling, and the mold was cooled to 80 ° C. in about 10 minutes and demolded.

  The carbon fiber reinforced thermoplastic epoxy resin molding obtained by demolding had a glass fiber content of 50% by volume, and no bubbles were observed on the surface or cross section, and the surface was beautiful. In addition, since this molded object was remelted only by heating at 160-180 degreeC for 1 minute, it was able to bend easily and it has confirmed that it was a linear polymer which does not have a crosslinked structure.

  Next, a flat plate was cut from the flat portion of the obtained carbon fiber reinforced thermoplastic epoxy resin molded body (hereinafter referred to as “thermoplastic CFRP”) into a width of 300 mm × length of 300 mm × thickness of 4 mm, and a bending test and dynamic viscosity were determined. Elasticity test measurements were taken.

Comparative Example 1
CFRP using a thermosetting epoxy resin as a base material, hereinafter referred to as “RefCFRP”. ) Were measured and compared. Detailed molding conditions and material specifications of RefCFRP are as follows.
Bisphenol A type liquid epoxy resin (trade name: Epicoat 828) manufactured by Yuka Shell Epoxy Co., Ltd .: Liquid methyltetrahydrophthalic anhydride (trade name: MT-500TZ) manufactured by Shin Nippon Rika Co., Ltd .: Kayaku Akzo 2,4,6-Tris (dimethylaminomethyl) phenol octylate (trade name: S-Cure 661) manufactured by Co., Ltd. was mixed and stirred at a ratio of 100: 80: 1 by weight, and the mixture was mixed with HLU method. In a dry carbon fiber fabric (plain weave carbon cloth, C06343 manufactured by Toray Industries, Inc., thickness: 0.25 mm, weight: 195 g / m 2) Press molding was performed at 100 ° C. for 1 hour and then at 150 ° C. for 3 hours at a molding pressure of 1.0 MPa. The finished dimensions and fiber volume content of the RefCFRP laminate were adjusted to be the same as the thermoplastic CFRP molded by the injection molding method of Example 1 by pressing with a 4 mm spacer during pressing. The thickness t = 4 mm and the fiber volume content was 50%.

Viscoelasticity test:
The measurement was performed by a dynamic viscoelasticity test according to JIS K7244-5. The test piece has a thickness h = 4 mm, a width b = 10 mm, and a length l = 20 mm. A dynamic viscoelasticity measuring machine DMS-6100 (manufactured by Seiko Instruments Inc.) was used as a test machine, both ends were completely fixed, a sample central part was clamped with a width of 5 mm, and sinusoidal strain due to bending was applied. The test conditions were a measurement temperature of −50 to 250 ° C., a temperature increase rate of 2 ° C./min, and an excitation frequency of 1 Hz.
Bending test:
The static bending strength and elastic modulus were measured by a three-point bending test according to JIS K 7017. The test piece has a height h = 4 mm, a width b = 15 mm, a length l = 80 mm, and a bending span of 60 mm. The measurement temperature is 25 ° C.

  The measurement results of the storage elastic modulus (E ′) and the measurement results of tan δ are shown in FIG. 3 (Example 1) and FIG. 4 (Comparative Example 1). Regarding the storage elastic modulus (E ′), the thermoplastic CFRP of Example 1 and the RefCFRP of Comparative Example 1 show substantially the same value, and the temperature at which E ′ decreases rapidly (corresponding to Tg) is the value of RefCFRP. A slightly high value was shown.

  From the temperature dispersion result of the loss (tan δ), in the case of RefCFRP, tan δ increased rapidly when Tg was reached, as shown by a normal thermosetting resin, and returned to the original low value above Tg (FIG. 4). On the other hand, in the case of thermoplastic CFRP, tan δ increases rapidly when Tg is reached, but maintains a high value without returning to the original tan δ value although it slightly decreases even at higher temperatures. 3). This indicates that when the thermoplastic CFRP is equal to or higher than the Tg of the base material, the viscous property increases and is melted (reliquefied).

  Table 2 shows the results of the three-point bending test. From these results, it was found that the fiber-reinforced thermoplastic epoxy resin of the present invention has very high mechanical properties compared to RefCFRP using a thermosetting epoxy resin that is three-dimensionally crosslinked as a matrix. .

  The composite material produced by the molding method of the present invention exhibits mechanical properties equivalent to a fiber reinforced resin (FRP) using a thermosetting resin as a matrix resin at around room temperature (for example, 20 ° C. to 100 ° C.). A fiber-reinforced thermoplastic epoxy resin molded body that can be easily liquefied at a high temperature (for example, 160 ° C. or higher) and can be subjected to secondary processing, reuse, and recycling can be obtained. Moreover, the fiber reinforced thermoplastic epoxy resin molding which improved heat resistance is obtained by using the compound which has a fluorene skeleton as at least one part of a compound (A) and / or at least one part of a compound (B). It can be applied to automobile applications such as platforms, bonnets, bumpers, doors, roofs, seats, spoilers, truck cab roof spoilers, bus bodies, and the like.

It is a figure which shows the injection molding apparatus of the fiber reinforced thermoplastic epoxy resin of Example 1. FIG. It is a figure which shows the viscoelasticity test result of the fiber reinforced thermoplastic resin (thermoplastic CFRP) of Example 1 of this invention. It is a figure which shows the viscoelastic test result of RefCFRP of the comparative example 1.

Explanation of symbols

01, 03 Heating resin tank 02 Cleaning tank 06, 08 Resin piping 07 Cleaning agent piping 04, 05 Gear pump 09, 10 Flow meter 11 Static mixer 12 Inlet 13 Mold

Claims (9)

Injecting a compound (A) having two epoxy groups in one molecule and a compound (B) having two phenolic hydroxyl groups in one molecule into a mold in which reinforcing fibers are arranged in advance, The step (I) of mixing with the reinforcing fiber, and the compound (A) and the compound (B) mixed with the reinforcing fiber are combined in the mold with the compound (A) and the compound (B). ) And a polymerization catalyst and a reaction retarder to form a linear polymer by a polyaddition reaction to form a thermoplastic resin obtained by polymerizing the compound (A) and the compound (B) (II) And a method for forming a fiber-reinforced thermoplastic resin. The molding method according to claim 1, wherein the temperature at which the compound (A) and the compound (B) are polymerized is 100 to 200 ° C. In the step (I), the compound (A) and the compound (B) are injected into a mold in which reinforcing fibers are arranged in advance in a molten state and impregnated in the reinforcing fibers. 2. The molding method according to 2. The molding method according to any one of claims 1 to 3, wherein a phosphorus polymerization catalyst and a borate ester reaction retarder are used. The molding method according to claim 1, wherein at least a part of the compound (A) and / or at least a part of the compound (B) is a compound having a fluorene skeleton. The compound (A) is heated and melted in the first resin tank, the compound (B) is heated and melted in the second resin tank, and the compound (A) supplied from the first resin tank and the second resin tank are used. The molding method according to claim 3, wherein the compound (B) to be supplied is mixed and then injected immediately before being injected into the mold. The molding method according to any one of claims 1 to 6, wherein the compound (A) and the compound (B) are injected into a mold whose inside is decompressed. The mold includes a first mold and a second mold, and either the first mold or the second mold is made of a resin or rubber film, and the first mold and the second mold The molding method according to claim 7, wherein the compound (A) and the compound (B) are injected while the inside of the mold surrounded by the mold is decompressed. The molding method according to claim 1, wherein the reinforcing fiber is a glass fiber, a carbon fiber, or an aramid fiber.

Images