JPH09227694A - Fibrous reinforcement, production of the fibrous reinforcement, and structural material containing the fibrous reinforcement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion and interfacial strength of polyamide fibers without impairing the mechanical properties thereof by treating the surface of a fibrous reinforcement with a cured epoxy resin. SOLUTION: A surface-treated fibrous reinforcement is produced by impregnating a fibrous reinforcement with 0.1 to 1.0wt.% epoxy resin and, if necessary, heat-treating it at 280 to 400 deg.C in an inert gas atmosphere to cure the epoxy resin. A starting monomer mixture for polyamide fibers is reaction injection- molded in a mold laminated with the fibrous reinforcement to give a structural material containing the polyamide fibers containing the fibrous reinforcement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced material, a method for producing the fiber reinforced material, and a structural material containing the fiber reinforced material, and in particular, RIM nylon as a matrix resin. It can be used for machine parts, automobile parts, armor and sports equipment. Specifically, robot arms, car skins, helmets, racket frames,
It is preferably used when molding a club shaft, a club head, a leaf spring, a wheelchair, a bumper, an anti-vibration material, an electromagnetic wave shielding material, etc. with a fiber reinforced resin.

[0002]

Conventionally, an FRP product (fiber reinforced resin product) made of nylon (RIM nylon) reinforced with a fiber reinforced material and reaction injection molded has hitherto been used. Japanese Patent Fairness related to
As disclosed in No. 33645, the characteristics of nylon, which is a matrix resin, are utilized to provide a FRP product having good vibration damping properties, high toughness, and high impact strength. Further, by using continuous fibers as the reinforcing fibers, it is possible to obtain a molded product having high rigidity and strength with respect to weight (so-called specific rigidity, specific strength).

The above mechanical properties are obtained when the interfacial adhesion strength between the fiber reinforcement and the matrix resin RIM nylon is sufficient. Therefore, in order to improve the boundary adhesion strength between the fiber reinforcement and the matrix resin,
Various methods for surface treatment of fiber reinforcement are provided. However, there has been a problem that the interfacial adhesive strength is not yet sufficient with the surface treatment technology of the fiber reinforced material provided so far.

As described in the prior art of Japanese Patent Publication No. 5-33645, conventionally, an epoxy resin is generally used as a surface treatment agent for fiber reinforced materials. However, using RIM nylon as the matrix resin,
In the case of reaction injection molding, it is known that the epoxy resin causes polymerization inhibition during the reaction of RIM nylon, resulting in a significant decrease in mechanical properties. This is because the epoxy group, which is the surface treatment agent for the fiber reinforcement, reacts with sodium hydride, sodium methoxide, sodium caprolactam and the like contained in the RIM nylon catalyst, and the RIM nylon catalyst is insufficient.

In order to solve the above problems,
In No. 33645, as a surface treatment agent for a fiber reinforced material, an alcohol-soluble, water-soluble or both alcohol- and water-soluble nylon is used as a surface treatment agent instead of an epoxy resin. However, this soluble nylon does not have good adhesiveness with nylon itself, and particularly has poor adhesiveness with carbon fibers. Further, soluble nylon has a high water absorption property, and as the matrix RIM nylon absorbs water, it tends to absorb more water. As a result, the adhesive strength at the interface between the fiber reinforced material and the matrix resin decreases, and the mechanical properties are reduced. In particular, there is a drawback that the shear strength is likely to decrease due to water absorption.

[0006] Furthermore, the applicant of the present invention has issued a Japanese Patent Publication No. 7-578.
No. 09 provides a method for treating the surface of a fiber reinforcement by coating the surface of the fiber reinforcement with a metal. However, although it is effective when the fiber reinforcing material is an organic fiber, it cannot be said that an inorganic fiber such as carbon fiber or glass fiber is effective because the adhesion to the metal film is not sufficient.

Further, a silane coupling agent may be used as a surface treatment material for the fiber reinforcement. The silane coupling agent was not effective for carbon fibers, but was considered effective for glass fibers. However, when confirmed with an actual molded product, there is no problem in the dry state, but a problem occurs when the moisture absorption of the matrix resin RIM nylon progresses. This is because the RIM nylon catalyst makes the glass fibers alkaline, and the alkali deteriorates the glass fibers, causing many cracks in the fibers. This is confirmed by the observation of the fracture surface by the SEM image.

For example, when the fiber content is 50 vol%,
The water absorption of the glass fiber with respect to nylon becomes 5%, and the strength of the structural material decreases to 35%. It has been confirmed that this reduced strength does not recover even when dried again. In order to confirm the corrosiveness of the glass fiber by the above alkali, a solution prepared by adding water to a monomer containing a RIM nylon catalyst was prepared and the glass fiber was immersed (9
0 ° C., 2 hours). As a result, the glass fiber was brittle.

The reason why the glass fiber is eroded by the alkali and becomes brittle is considered to be due to the following chemical reaction,
It is considered that NaOH generated by the formula (1) cleaves the Si-O bond according to the formula (2).

[0010]

Embedded image

The present invention has been made in view of the above problems, and can improve the interfacial adhesion strength between the fiber reinforcement and the matrix resin RIM nylon and suppress the deterioration of mechanical properties due to water absorption. An object of the present invention is to provide a surface-treated fiber reinforced material, a method for producing the fiber reinforced material, and a structural material comprising a fiber reinforced resin product containing the fiber reinforced material.

[0012]

As described above, when the epoxy resin is used as the surface treatment agent for the fiber reinforcement, R
It was generally considered that the surface treatment with the epoxy resin was unsuitable because the strength of the produced molded product was remarkably decreased because the IM nylon was inhibited by polymerization during the reaction. On the other hand, the present inventor has noticed that the epoxy resin itself has good adhesiveness to fibers, and the epoxy resin can be used as a surface treatment agent as long as it does not cause polymerization inhibition during the reaction of RIM nylon. In that case, it was considered that the boundary adhesive strength between the fiber reinforcement and RIM nylon could be increased. Therefore, focusing on the fact that the cause of polymerization inhibition is the epoxy group, and curing the epoxy resin used as the surface treatment agent, the RIM caused by the epoxy group
Suppresses the polymerization inhibition that occurs during the reaction of nylon, and
It has been found that the water absorption of the fiber reinforcement is suppressed.

Based on the above points, the present invention provides claim 1.
The matrix resin is a fiber reinforced material used in a fiber reinforced resin made of a reaction injection molded polyamide resin,
The present invention provides a fiber reinforced material, which comprises surface-treating a cured epoxy resin on the surface of the fiber reinforced material.

As the epoxy resin used as the surface treatment agent,
An epoxy resin having an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor is used. Specifically, various epoxy isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl-P-aminophenol, triglycidyl-m-aminophenol, and triglycidylaminocresol are listed as epoxy resins having amines as precursors. Bisphenol A type epoxy resin as an epoxy resin using phenols as a precursor,
Bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin,
Examples include cresol novolac type epoxy resin and resorcinol type epoxy resin. Examples of the epoxy resin containing a compound having a carbon-carbon double bond as a precursor include alicyclic epoxy resins.

The amount of the hardened epoxy resin deposited is preferably 0.1% to 1.0% of the weight of the fiber. (Claim 2) This adhesion amount is smaller than the adhesion amount (about 1.5%) when a conventional uncured epoxy resin is used as a fiber surface treatment agent.

The amount of the cured epoxy resin deposited is
If it exceeds 1.0%, the fiber reinforcing material is apparently harder than the uncured epoxy resin, and the handling becomes difficult. When manufacturing pipe-shaped molded products with fiber reinforced resin,
It is necessary to wind the reinforcing fiber around the tube, set it in the mold, apply pressure inside the tube, and cause the fiber reinforcing material to follow the mold by the internal pressure. However, if the amount of adhesion is large,
Even if internal pressure is applied, there is a problem in that it does not follow the mold well, the amount of the RIM nylon resin increases, the weight of the molded product increases, and the fiber content decreases. In addition, since the cured epoxy resin does not flow, if a large amount is attached, when the matrix resin is molded with RIM nylon, the cured epoxy resin blocks the penetration of RIM nylon into the fiber, and the RIM inside the fiber is blocked. Nylon penetration is poor.

On the other hand, if the amount of the hardened epoxy resin attached is less than 0.1%, the ratio of the coating on the fiber surface becomes small, and the mechanical properties vary. In addition, the fiber sizing effect is small. As a result, when the RIM nylon monomer is injected after the reinforcing fiber is placed in the mold, the displacement of the reinforcing fiber occurs due to the monomer injection pressure. Further, since the sizing effect is small, when the fiber such as a braid is used, the fibers are often scattered and the fibers are often cut. Furthermore, when a braid is formed from a fiber reinforcement material that has been surface treated with a cured epoxy resin, and when this braid is used to form a pipe-shaped fiber laminate, the braid sags due to the weight of the fiber itself, making it impossible to maintain the shape of the braid. . As a result, the design angle cannot be formed. In particular, this phenomenon is remarkable when the angle is small.

Further, according to the present invention, in claim 3, an epoxy resin is used as a surface treatment agent, the epoxy resin is impregnated with a fiber reinforcement, and then heated to cure the epoxy resin on the surface of the fiber reinforcement. The present invention provides a method of manufacturing a fiber reinforced material.

Specifically, there are two cases, that is, a case where a curing agent is added to the epoxy resin of the surface treatment agent and a case where the curing agent is not added.
There are types. In the first method of adding a curing agent, a surface treatment agent obtained by adding a curing agent to an epoxy resin is provided, the fiber treatment material is impregnated with the surface treatment agent, and then the epoxy resin is heated to cure the epoxy resin. The cured epoxy resin is attached to the surface of the fiber reinforcement. The curing agent for the epoxy resin may be any compound having an active group capable of reacting with an epoxy group, and examples thereof include amines, acid anhydrides and imidazoles. Specifically, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, dicyandiamide, boron trifluoride complex, polyphenyl compound and the like can be used. Further, these curing agents may be used in combination with imidazoles, urea compounds and the like as a curing accelerator.

The epoxy resin and the curing agent are dissolved in a solvent, and the fiber reinforcing material is immersed in this solution to impregnate the surface of the fiber reinforcing agent with the epoxy resin containing the curing agent. Then, it is heated at 120 to 180 ° C. to cure the epoxy resin.

In the second method, the fiber reinforced material is surface-treated with an epoxy resin containing no curing agent and then heat-treated,
It is self-polymerized by heating to cure the epoxy resin. The heat treatment atmosphere for the self-polymerization may be in an inert gas or in the air, but in the case of carbon fibers, an inert gas atmosphere is preferable in consideration of deterioration due to oxidation of carbon. The heat treatment temperature is
It is preferably 280 ° C to 400 ° C. Note that 40
At 0 ° C. or higher, the oxygen concentration in the atmosphere becomes high, and the deterioration of the carbon fiber progresses, but at 280 ° C. or higher, the epoxy resin does not self-polymerize. This is confirmed by the reduction of the epoxy group peak by TGA (thermogravimetric analysis) and IR of the sample after DSC measurement.

It is also possible to apply a predetermined amount or more of epoxy resin to the fiber reinforced material, cure it by the above heat treatment, and burn off unnecessary epoxy resin. The amount of this burn-off can be controlled by the heat treatment time. When this method is used, a reinforcing fiber material whose surface is treated with a general-purpose epoxy resin can be used, which is advantageous in terms of cost.

According to a fourth aspect of the present invention, there is provided a structural material comprising a polyamide resin reinforced with a fiber reinforcing material, wherein the polyamide resin is formed by reaction injection molding, and the fiber reinforcing material is a cured epoxy resin. There is provided a structural material including a fiber reinforced material which is surface-treated.

As described above, the fiber reinforced material having the cured epoxy resin adhered to the surface thereof has good adhesiveness to the fiber itself and the matrix resin and is cured, so that it does not cause polymerization inhibition by the epoxy group. Does not lower the mechanical properties of the polyamide resin.

The fiber reinforcement of the present invention is not limited in fiber length, and may be continuous fiber, long fiber or short fiber, and the fiber form is also not limited. Further, in the structural material including the polyamide resin and the fiber reinforcing material, the fiber content is not limited.

The type of fiber reinforcing material is not limited, but inorganic fibers are more effective. For example, even carbon fibers having poor adhesiveness can be bonded with a strong adhesive force. Further, even in the case of glass fiber which is easily deteriorated by alkali, it becomes difficult to absorb water by adhering to the surface thereof, and it is possible to suppress the strength reduction due to water absorption.

As described above, in the structural material composed of the fiber reinforced RIM nylon, the surface treatment is improved by adhering the hardened epoxy resin to the surface of the fiber reinforced material.
The mechanical properties of the molded product can be significantly improved.
Further, if the physical property values are the same as the conventional ones by improving the mechanical property values, the weight of the product can be reduced.

[0028]

Embodiments of the present invention will be described below. In order to compare the mechanical physical property value of the example of the present invention and the mechanical physical property value of the conventional example, a comparative example corresponding to the conventional example was also prepared, and a three-point bending test of JIS-K7055 was performed.
Bending elastic modulus and bending fracture stress were measured.

In Example 1, a carbon fiber plain weave cloth (manufactured by Toho Rayon (W3101)) was used as the fiber reinforcing material.
Was used to impregnate an epoxy resin containing no curing agent, and 1.7 wt% was adhered to the surface as a sizing agent. This is 3
The epoxy resin was cured by heat treatment at 00 ° C. for 6 hours. The final amount of epoxy resin deposited was 0.8%. Twenty layers of the carbon fiber plain weave cloth having the surface of the cured epoxy resin attached thereto were placed in a mold having a width of 300 mm, a length of 150 mm and a thickness of 4 mm. The mold is heated to 150 ° C,
A two-liquid mixed solution of raw material monomers of RIM nylon was injected into the mold. The injection pressure was 5 kgf / cm ² and the molding was completed by holding for 3 minutes. The RIM nylon used is U made by Ube Industries.
X-75.

This molded product was processed into a test piece having a width of 10 mm, a length of 150 mm and a thickness of 4 mm, and the sample supporting length was 8 mm.
A three-point bending test of JIS-K7055 was performed with the value set to 0 mm, and the bending elastic modulus and bending fracture stress were measured. The sample was kept at 23 ° C and 55RH% for 6 days,
It measured in the same atmosphere.

A sample having the same shape was tested at 32.5 ° C. 9
It was stored at 0 RH% for 40 days and used as a water absorption strength test. The water absorption rate was about 6.5% with respect to the matrix nylon.

In Example 2, as in Example 1, an epoxy resin containing no curing agent was impregnated with carbon fibers, and then heated at 300 ° C. for 24 hours for heat treatment to cure the epoxy resin. Same as Example 1 except that the amount of the cured epoxy resin attached to the carbon fiber is 0.3%.

In Example 3, a plain weave cloth made of E-glass as a fiber reinforcing material (WE-18KB manufactured by Nitto Boseki Co., Ltd.) was used.
Z) was used. A silane coupling agent was applied to the surface of the glass fiber, and 1.8 wt% of an epoxy resin (Epocoat 828) was attached. Then, it heat-processed at 300 degreeC for 6 hours, and hardened the epoxy resin. The final adhesion amount of the epoxy resin was 0.9%. Twenty-one layers of the surface-treated glass fiber were laminated in a mold. The casting conditions and physical property measuring conditions of RIM nylon are the same as in Example 1.

In Example 4, the same fiber reinforcing agent as in Example 1 was used and impregnated with an epoxy resin containing a curing agent. The epoxy resin main agent was Epicoat 828, the curing agent was aromatic amine DDS (diaminodiphenyl sulfone), and the mixing ratio was 100: 37. Adhesion amount is 0.7%, 15
Curing treatment was performed at 0 ° C. for 2 hours. The carbon plain weave cloth in this state was molded by injecting RIM nylon monomer in the same manner as in Example 1.

In Comparative Example 1, the same carbon fiber plain weave cloth as in Example 1 was used as a fiber reinforcement, and this was immersed in soluble nylon (A-70 manufactured by Toray) which was melted in ethanol. The final amount of nylon attached after removing the solvent was 0.8% by weight. This fiber reinforcement was placed in a mold. The casting conditions and physical property measuring conditions of RIM nylon are the same as in Example 1.

In Comparative Example 2, the fiber reinforcing material of Example 1 was not heat-treated, but ultrasonic cleaning was performed using a solvent mixed with toluene, MEK and isopropyl alcohol to remove the epoxy surface treatment. Other than that is the same as that of the first embodiment. In Comparative Example 2, the fiber holding effect was low, and the reinforcing fibers moved due to the monomer injection pressure.

In Comparative Example 3, the same glass fiber as in Example 3 was used as the fiber reinforcing material, and the surface thereof was treated only with the silane coupling agent. Other than that is the same as the third embodiment.

Examples 1 to 4 and Comparative Example 1
Through the measurement results of bending elastic modulus and bending fracture stress by the three-point bending test of JIS-K7055 of Comparative Example 3, the following Table 1 is shown.
Shown in

[0039]

[Table 1]

As shown in Table 1 above, comparing Example 1 and Example 2 using carbon fiber as the fiber reinforcing material with Comparative Example 1 and Comparative Example 2, an example in which the fiber contents were equal In Comparative Example 1 and Comparative Example 1, it was proved that Example 1 was superior to Comparative Example 1 both in the normal state and in the warm normal state, with large numerical values of bending elastic modulus and bending fracture stress and excellent mechanical properties. did it. Similarly, in the example 2 and the comparative example 2 in which the fiber contents are the same, the example 2 is the comparative example 2
From this, it was proved that the flexural modulus and flexural fracture stress were large and the mechanical properties were excellent both in the normal state and in the warm normal state. Furthermore, Example 3 in which glass fibers were used as the fiber reinforcement and the fiber content was the same
Comparing with Comparative Example 3, Example 3 is
It was verified that the flexural modulus and flexural fracture stress were large and mechanical properties were excellent both in the normal state and in the normal state of heating.

Further, the racket frames of Examples 4 to 6 made of the fiber-reinforced resin of the present invention were molded. In order to compare the rigidity and strength of the racket frame of the example of the present invention with the rigidity and strength of the conventional racket frame made of fiber reinforced resin, a comparative example equivalent to the conventional example was also prepared, and the racket frame flat The pressure stiffness and the compressive strength were measured.

In Example 5, carbon fiber braid (BC7364-24 manufactured by Toho Rayon Co., Ltd.) was used as the fiber reinforcing material.
(20), BC73664-45 (20)) and 1.7 wt% of epoxy resin (without curing agent) as a sizing agent.
% Adhered. This was heat-treated at 300 ° C. for 6 hours to cure the epoxy resin. Finally, the adhesion amount of the epoxy resin was 0.8%. The surface-treated carbon fiber braid had a width of 12 mm and a thickness of 22 mm and was laminated to prepare a sleeve-shaped layup to be placed in a racket frame mold. A 66 nylon tube was inserted into the inner layer of this sleeve-shaped layup, and pressure was applied inside to achieve hollow molding. The mold was heated to 150 ° C., and a two-liquid mixed solution of raw material monomers of RIM nylon was injected into the mold. The injection pressure was set to 5 kgf / cm ^2, and the molding was completed by holding for 3 minutes to produce a racket frame. The RIM nylon used is UX-75 manufactured by Ube Industries. The sample of this racket frame manufactured is 23 ° C, 55R
The sample was kept in the H% state for 6 days, and the above-mentioned compression rigidity and compression strength were measured under the same atmosphere.

A sample of the same shape was tested at 32.5 ° C. 90
It was stored at RH% for 40 days and used as a water absorption strength test. The water absorption rate was about 6.5% with respect to the matrix nylon.

Example 6 was the same as Example 5 except that the heat treatment of the fiber reinforcement placed in the mold of the racket frame was 300 ° C. for 24 hours, and the amount of epoxy resin adhered was 0.3%. Is.

In Example 7, the fiber reinforcement is the same as in Example 5. However, the surface treatment agent and treatment method for the fiber are the same as in Example 4, and a curing agent is used.

In Comparative Example 4, soluble nylon (Toray A-70) obtained by melting the surface treatment of the fiber reinforcement in ethanol was used.
The same as Example 5 except that it was immersed in The final deposited amount after removing the solvent was 0.8 wt%.

In Comparative Example 5, the fiber reinforcing material of Example 1 was not heat-treated, but ultrasonic cleaning was performed using a solvent mixed with toluene, MEK and isopropyl alcohol to remove the epoxy surface treatment. Other than that is the same as the fifth embodiment. In the fiber reinforced material of this example, it was difficult to maintain the fiber angle when laminated on the mold, and the variation of the fiber angle in the molded product became large.

In Comparative Example 6, the fiber reinforced material of Example 5 was heat treated at 300 ° C. for 6 hours. However, the amount of the epoxy resin initially attached was 2.5 wt%. The adhesion amount after heat treatment was 1.2 wt%. Other than that is the same as the fifth embodiment. In Comparative Example 6, the fiber at the time of layup was stiff,
Workability was poor. Also, because of this hardness, the reinforcing fibers did not follow the mold well, and the weight of the molded product increased.

Examples 4 to 6 and Comparative Example 4
A flat-pressure rigidity test of the racket frame of Comparative Example 6 was performed. In this flatness rigidity test, with the frame horizontal, the lower part near the top part side and the grip end side is supported by a support tool, and the center point between the top part and the grip end is the same with the pressing tool from above. Was applied to measure.

The racket frames of Examples 4 to 6 and Comparative Examples 4 to 6 were subjected to a compressive strength test. This measurement was performed under the same test conditions with the same device as the above-mentioned pressure bearing rigidity test, and the load value at the time of breaking was read to measure the pressure bearing strength.

Table 2 below shows the results of measurement of the weight of molded products, compression rigidity and compression strength of Examples 4 to 6 and Comparative Examples 4 to 6.

[0052]

[Table 2]

As shown in Table 2, in Example 5 and Comparative Example 4 in which the weight of the molded product is the same in the normal state and the normal state of heating, Example 5 has a larger compression rigidity and compression strength than Comparative Example 4, It has excellent mechanical properties. Similarly, in Example 5 and Comparative Example 5 in which the weight of the molded product is the same in the normal state and the normal state of heating, Example 6 has a higher compression rigidity and compression strength than Comparative Example 5, and has excellent mechanical properties. . Further, in Comparative Example 6, although the weight of the molded product is larger than that in Example 5, the compression rigidity and the compression strength are smaller than those in Example 5.

[0054]

As is clear from the above description, according to the present invention, since the cured epoxy resin is adhered to the surface of the fiber reinforced material, the RIM used as the matrix resin.
Does not cause polymerization inhibition during the reaction of nylon. Therefore,
Does not cause deterioration of mechanical properties of RIM nylon. Further, the epoxy resin adhering to the surface of the fiber reinforcing material has good adhesiveness with the fiber and also has good adhesiveness with RIM nylon, so that the interfacial strength between the fiber reinforcing material and the matrix resin can be sufficiently maintained. . Therefore, the mechanical properties of the fiber-reinforced resin product can be improved from this point.

Further, the method of adhering the cured epoxy resin to the surface of the fiber reinforced material and performing the surface treatment is to impregnate the epoxy resin with the curing agent (or without the curing agent) and heat it. Good and easy, it is possible to produce a fiber reinforced material to which a cured epoxy resin is attached.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C08L 77/00 KLC C08L 77/00 KLC // C08L 63:00

Claims (4)

[Claims] 1. A fiber reinforced material for use in a fiber reinforced resin comprising a polyamide resin in which a matrix resin is reaction injection molded, wherein a cured epoxy resin is adhered to the surface of the fiber reinforced material for surface treatment. A fiber reinforced material characterized in that 2. The fiber reinforcing material according to claim 1, wherein the amount of the cured epoxy resin deposited is 0.1% to 1.0% of the weight of the fiber. 3. An epoxy resin is used as a surface treatment agent,
After impregnating the epoxy resin with the fiber reinforcement, heat it to
A method for producing a fiber-reinforced material, wherein an epoxy resin on the surface of the fiber-reinforced material is cured. 4. A structural material comprising a polyamide resin reinforced with a fiber reinforcement, wherein the polyamide resin is formed by reaction injection molding, and the fiber reinforcement is surface-treated with a cured epoxy resin. Structural materials, including reinforcements.