JP2001294688A - Laminate with flexible interfacial layer and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminate with a reinforcing base of glass fiber, excellent in drilling processability and the resistance to damage under stress loading, and to provide a method for producing such a laminate. SOLUTION: This laminate 1 is obtained by mutually laminating prepregs each prepared by impregnating a reinforcing base 11 of glass fiber with a matrix resin 3, wherein a flexible interfacial layer is formed with a low-modulus resin 2 made of such a material with low elastic modulus as to absorb stress transmission, each between the reinforcing base 11 and the matrix resin 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a laminate obtained by impregnating a matrix resin into a reinforcing substrate made of glass fiber and forming a laminate, and a method for producing the same.
The present invention relates to a laminate having a flexible interface layer in which the surface of a glass fiber constituting a reinforcing substrate is covered with a low-elastic resin, and a method for producing the same.

[0002]

2. Description of the Related Art In a laminate using glass fiber as a reinforcing material,
In general, the adhesion between the glass fiber and the matrix resin poses a problem. Therefore, a method has been adopted in which a coupling agent is treated to form an adsorption layer of the coupling agent on the surface of the reinforcing material.
(See, for example, JP-A-4-192489).

That is, by forming an adsorbing layer between the reinforcing material and the matrix resin, the adsorbing layer is chemically bonded to the reinforcing material and the matrix resin, and the adhesion between the reinforcing material and the matrix resin is improved. It has become something.

[0004]

However, in a conventional corrosion resistant laminate, in a quality evaluation test in which a thermal shock or stress is applied, delamination, peeling at a crossing portion between a glass cloth warp and a weft, and a fiber Debonding may occur at the fiber-resin interface inside the bundle, and in particular, in the case of a laminate for applications requiring corrosion resistance, the reliability of the product may decrease due to defects such as delamination and debonding. There was a problem.

Further, in a conventional laminate using glass fiber as a reinforcing material, the adhesiveness between the reinforcing material and the matrix resin at the time of drilling for assembling parts has a strength enough to withstand mechanical processing such as drilling. Since it did not have, microcracks 4 as shown in FIG. 3 were sometimes generated inside the glass fiber bundle during processing.

When used in a corrosion-resistant application in which a microcrack is exposed to chemicals in the presence of such microcracks, the corrosive liquid penetrates into the voids created by the microcracks, and acts directly on the glass fibers and the interface to shorten the life. . Practically avoiding these factors, it takes a large safety factor to achieve very low stress (for example, a safety factor of 10 (1/1 of static strength).
0)).

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a laminate excellent in drilling workability and occurrence of damage when stress is applied, and a method of manufacturing the same. Things.

[0008]

In order to achieve the above-mentioned object, the inventors of the present application have developed such a microcrack which occurs when glass fiber is used as a reinforcing base material, by using a machine such as a drilling machine. This is because stress is generated at the interface due to a large difference in the elastic modulus between the reinforced base material and the matrix resin due to mechanical processing load or stress load, and the chemical bonding force by the conventional coupling agent treatment can withstand such stress. As a result of extensive research on countermeasures, a flexible interface layer made of a material with a low elastic modulus capable of absorbing stress transmission was formed between the reinforcing base material and the matrix resin. They have found that they are effective, and have completed the present invention based on this finding.

That is, the present invention relates to a laminate obtained by laminating and molding a prepreg obtained by impregnating a matrix resin into glass fibers serving as a reinforcing substrate, and a method for producing the same, particularly, the reinforcing substrate. An object of the present invention is to provide a laminate in which glass fibers are covered with a low elasticity resin and a method for producing the laminate.

Hereinafter, the present invention will be described in detail.

A laminate according to claim 1 of the present invention is a laminate in which a prepreg in which a matrix resin is impregnated on a reinforcing substrate made of glass fiber is laminated, wherein the surface of the glass fiber constituting the reinforcing substrate is formed by the matrix. The flexible interface layer is formed by coating with a low elastic resin having an elastic modulus of 50% or less of the resin.

According to such a laminate, a structure in which a low elasticity resin is interposed between the matrix resin and the reinforcing base material is used. The stress generated at the interface is reduced by the difference in the elastic modulus of the matrix resin.

Further, in the laminate according to claim 2, the low elasticity resin has a tensile elasticity of 1.OGPa or less or a tensile breaking strain of 20% or more, and the matrix resin has a tensile elasticity of not less than 20%. 2.0 GPa or more, or tensile breaking strain of 10
% Or any of the following:

According to such a laminate, the stress at the interface generated at the time of a thermal shock load, a mechanical processing load, and a stress load is particularly effectively reduced, so that the elastic modulus between the reinforcing base material and the matrix resin is reduced. The effect of preventing defects such as delamination and debonding caused by the difference is remarkable.

The laminate according to claim 3 is characterized in that the low elasticity resin is an iso-unsaturated polyester resin modified with polypropylene glycol in tensile modulus.

According to such a laminate, the tensile modulus of the low-elasticity resin is 1.OGPa or less, or the tensile breaking strain is 20%.
%, The stress at the interface generated at the time of thermal shock load, mechanical processing load, and stress load is particularly effectively reduced.

The laminate according to a fourth aspect is characterized in that the adhesion rate of the low elasticity resin to the glass fiber surface is 0.1 to 3.5%, preferably 0.4 to 2.0%.

According to such a laminate, the adhesion rate is 0.1%.
Mechanical processing and load strain of 0.2% when:
The occurrence of microcracks as described above can be reduced and prevented.

[0019] The laminate according to claim 5 is a case where the laminate is processed, and the prepreg is arranged at a portion where damage is likely to occur during the processing.

According to such a laminate, the prepreg is disposed at a portion where damage is likely to occur during processing. The generation of cracks can be reduced and prevented, and the decrease in heat resistance of the laminate due to the addition of the low elastic resin can be minimized.

The laminate according to claim 6 is characterized in that the laminate is used as a structural member for corrosion resistance.

According to such a laminate, high mechanical stress, such as drilling for assembling parts or the like, can be obtained.
Since various defects caused by the adhesion between the reinforcing base material and the matrix resin can be reduced and prevented, the reliability of the product can be improved.

Further, according to a seventh aspect of the present invention, there is provided a method for manufacturing a laminate, comprising: forming a flexible interface layer on the surface of glass fiber constituting the reinforcing base material; In a method of molding a laminate by performing press molding, a step of coating a reinforcing substrate made of glass fiber with a resin having a small elastic modulus or a large tensile breaking strain with respect to a matrix resin, and The laminated body is manufactured by a step including a step of drying, a step of impregnating the matrix resin between the reinforcing base materials, and a step of curing the matrix resin together with the low elasticity resin.

According to such a method of manufacturing a laminate, it is possible to continuously produce a laminate in which the stress at the interface generated when a thermal shock load, a mechanical working load, and a use stress is applied is effectively alleviated. Can be.

In the method for manufacturing a laminate according to claim 8, the reaction of the flexible interface layer does not proceed at room temperature, increases the adhesiveness by being compatible with the matrix resin, and is formed during FRP molding and post-curing. It is characterized in that curing of the flexible interface layer is started.

According to such a method for producing a laminate, the resin used for forming the flexible interface layer (for example, FK2000 (trade name: manufactured by Showa Polymer Co., Ltd.)) is cured at a high temperature. An agent (for example, t-butyl benzoate) is compounded and adheres to the reinforcing base material by volatilization of the solvent, but hardening does not proceed at room temperature (prepreg state).
When a reinforced substrate (prepreg) having a flexible interface layer formed thereon is laminated and impregnated with a matrix resin, a low-elastic resin and a matrix resin (for example, R806 (trade name: Showa (Manufactured by Kobunshi Co., Ltd.) are compatible with each other to form a laminate having excellent adhesiveness, and cured at a high temperature (for example, at 100 ° C. for 1 to 3 hours) to obtain an integrated laminate.

If the flexible interface layer has been cured first, it becomes difficult to form in the laminating step, and reliable adhesion between the flexible interface layer and the matrix resin cannot be obtained.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited by these.

An embodiment of the laminate according to the present invention will be described with reference to the drawings.

FIGS. 1 (a), 1 (b) and 1 (c) are schematic structural views of a laminate according to an embodiment of the present invention.
1A is a partial perspective view of a laminate, FIG. 1B is a partial perspective view of a reinforcing base, and FIG. 1C is an end view of a glass fiber bundle constituting the reinforcing base.

In the figure, a laminated body 1 is composed of a glass fiber bundle 12 composed of a large number of glass fibers 10 as a warp and a weft, and a reinforcing substrate 11 in the form of a woven cloth laminated so that they intersect.
In addition, as shown in FIG. 1 (c), a flexible interface layer is formed by impregnating a matrix resin 3 on a surface of a glass fiber 10 constituting a reinforcing base material 11, as shown in FIG. Are formed, and a low elastic resin 2 is interposed between the matrix resin 3 and the reinforcing base material 11.

The matrix resin 3 used in the present invention is not particularly limited, and those generally used as matrix resins for FRP can be used. However, unsaturated polyester, vinyl ester resin, epoxy resin, and phenol resin are preferable from the viewpoint of ease of molding of the laminate 1, curing temperature, and other required physical properties.

When the laminate 1 according to the present invention is used for corrosion resistance, a matrix resin 3 containing a bisphenol-type unsaturated polyester resin and a vinyl ester resin is preferably used.

The low elastic resin 2 used for forming the flexible interface layer in the present invention may have an elastic modulus of 50% or less of the matrix resin 3, and is not particularly limited within the range.
Unsaturated polyester resins are preferred from the viewpoint of adhesion to 11 and the matrix resin 3 and the like.

The effect of the present invention can be obtained by using a vinyl ester resin in addition to the above.

Further, the combination of the matrix resin 3 and the low elastic resin 2 is such that the tensile elastic modulus of the low elastic resin 2 is 1.0 GPa or less, or the tensile breaking strain is 20% or more. The elastic modulus is 2.0 GPa or more, or the tensile breaking strain may be any one of 10% or less, but the tensile elastic modulus of the low elastic resin 2 is 0.5 GPa or less, or the tensile breaking strain is any of 40% or more. Preferably, the matrix resin 3 has a tensile modulus of 2.5 GPa or more, or a tensile strain at break of 5% or less.
(2) The tensile elastic modulus is 0.3 GPa or less, or the tensile breaking strain is 60% or more, and the tensile elastic modulus of the matrix resin 3 is 3.5 GPa or more, or the tensile breaking strain is 5% or less. Is more preferred.

In the combination of the matrix resin 3 and the low elastic resin 2, when the elastic modulus of the low elastic resin 2 is 50% or more of the elastic modulus of the matrix resin 3, the effect of the present invention as described above becomes stable. It was confirmed experimentally that it could not be obtained.

Further, when the low elastic resin 2 is a resin which does not solidify even after curing and becomes only a gel, when the matrix resin 3 is impregnated, the reinforcing substrate 1 is impregnated with a solution.
It was confirmed that the low elastic resin 2 was removed from the surface of 1 and a desired adhesion rate could not be obtained.

The form of the reinforcing substrate 11 in the present invention is preferably a woven cloth, a nonwoven cloth, or a mat form.

Hereinafter, the method for producing a laminate according to the present invention will be described.
This will be described in detail with reference to FIG.

A: First, a solution is prepared by dissolving a flexible resin FK2000 (trade name, manufactured by Showa Polymer Co., Ltd.) containing t-butyl benzoate which reacts at a high temperature as a curing agent in a styrene monomer.

B: The solution is immersed and impregnated with a reinforcing substrate having a woven fabric structure made of glass fiber.

C: Thereafter, room temperature, preferably 15 to 20 ° C.
For 10 to 60 minutes, preferably for 20 to 30 minutes, to evaporate the solvent component and increase the viscosity of the low-elastic resin, thereby forming a flexible interface layer of the low-elastic resin on the glass fiber surface constituting the reinforcing substrate. .

D: A plurality of the obtained reinforcing base materials are laminated and integrated by a hand lay-up method using a vinyl ester resin matrix containing methyl ethyl ketone peroxide which reacts at room temperature as a curing agent. obtain.

At this stage, the matrix resin partially cures but is not complete, and the flexible resin does not cure at this stage, and as a result, it is well compatible with the matrix resin and secures adhesiveness. Thereafter, post-curing is performed at 100 ° C. for 1 to 3 hours to obtain a laminate in which the flexible resin layer (interface layer) and the matrix layer are completely cured. (Example 1) A woven fabric made of glass fiber was added to a solution obtained by dissolving a flexible resin FK2000 (trade name, manufactured by Showa Polymer Co., Ltd.) containing t-butyl benzoate as a curing agent in a styrene monomer to a concentration of 1 wt%. After immersion and impregnation of a reinforcing substrate with a linear structure, it is dried for 25 minutes to volatilize the solvent component and thicken the low elastic resin, and coat the low elastic resin on the surface of the reinforcing substrate to form a flexible interface layer Then, a prepreg having a thickness of 0.18 mm was obtained, and ten prepregs thus obtained were laminated, and a vinyl ester resin R806 (trade name: Showa Polymer Co., Ltd.) containing methyl ethyl ketone peroxide as a curing agent was used as a matrix. The laminate was integrated by a lay-up method to obtain a laminate having a thickness of 2.0 mm. (Comparative Example 1) Vinyl ester resin R806 containing methyl ethyl ketone peroxide as a curing agent (trade name:
(Manufactured by Showa Polymer Co., Ltd.) were laminated and integrated by a hand lay-up method using a matrix to obtain a laminate having a thickness of 2.0 mm.

Each of the laminates obtained in Example 1 and Comparative Example 1 was subjected to a tensile test, and an AE (acoustic emission) during the tensile test was examined. FIG. 2 shows the results obtained in the test.

The tensile test was performed at a speed of 1 mm per minute using a tensile tester manufactured by Instron, and the AE was performed using a measuring machine manufactured by PAC. It is considered that the AE in this case corresponds to microfracture (generation of damage) during the tensile test.

From the results shown in FIG. 2, the laminate of Example 1 shows almost no decrease in tensile strength and elastic modulus as compared with the laminate of Comparative Example 1, but is superior in resistance to damage caused by stress. By interposing a flexible interface layer made of a low elasticity resin at the interface between the reinforcing base material and the matrix resin, it is possible to prevent the occurrence of damage when stress is applied. It was confirmed that the occurrence of microcracks could be reduced or prevented even in the case where the cracking was performed.

FIG. 3 is a schematic diagram showing the results of electron microscopic observation of the reinforcing base material and the matrix resin in the cross section of the test piece when the test was stopped during the test of the laminate of Comparative Example 1.
(A) and (b) show.

From the results shown in FIG. 3, it was confirmed that damages 4 and 5 occurred in the glass fiber bundle of the laminate. Example 2 In order to examine the dependence of the bending strength of the laminate according to the present invention on the treatment concentration, a flexible resin FK2000 (trade name: Showa Kogaku Co., Ltd.) containing t-butyl benzoate as a curing agent was treated with styrene. Dissolve in monomer and increase concentration
After impregnating a solution (0, 1, 3, 5 wt%) changed to 0 to 5 wt% with a reinforcing base material, which is a woven fabric structure made of glass fiber,
Dry for 25 minutes to evaporate the solvent component and thicken the low elastic resin, and form a low elastic resin layer on the reinforcing
A 0.18 mm prepreg was obtained, and ten prepregs thus obtained were stacked, and a hand lay-up method was performed using a vinyl ester resin R806 (product name: Showa Kogaku Co., Ltd.) containing methyl ethyl ketone peroxide as a curing agent as a matrix. To obtain a laminate having a thickness of 2.0 mm.

FIG. 4 shows the results of measuring the bending strength of each of the laminates obtained in Example 2 having different solution concentrations. The bending test is a three-point bending test at room temperature (distance between marks: 32 mm, test speed: 1
mm).

From the results shown in FIG. 4, it can be seen that in each of the laminates in Example 2, the bending strength and the flexural modulus of each laminate were the same as those in Comparative Example 1 even when the same treatment shown in Example 2 was performed. Compared to those, the elastic modulus slightly decreased, but the bending strength tended to slightly increase.

It is considered that the formation of the flexible resin layer (interface layer) shown in Example 2 contributed to alleviating the stress concentration at the fiber / resin interface.

[0054]

According to the present invention, the surface of the glass fiber constituting the reinforcing substrate is covered with a flexible resin layer (interface layer).
Since the stress at the interface generated at the time of thermal shock load, mechanical processing, and application stress load is effectively relieved, damage can be suppressed as a result, and a highly reliable composite material laminate can be provided.

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are schematic structural views of a laminate according to an embodiment of the present invention.

FIG. 2 is a graph showing a tensile stress-time-AE diagram in Comparative Example 1 and Example 1.

3 (a) and 3 (b) are a schematic cross-sectional view of a laminated body of a laminate of Comparative Example 1 showing damage occurrence points during a tensile test and an end view of a glass fiber bundle.

FIG. 4 is a graph comparing the processing concentration dependence of the bending strength of the laminate according to the embodiment of the present invention. .

FIG. 5 is a schematic diagram showing a configuration of a process for manufacturing a prepreg according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated body 2 Low elastic resin 3 Matrix resin 4 Micro crack 5 Separation part between fiber bundles 10 Glass fiber 11 Reinforcement base material 12 Glass fiber bundle

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F072 AA01 AA04 AA06 AA07 AB09 AB28 AB29 AC08 AD13 AD23 AD38 AG03 AG16 AG17 AH02 AH22 AJ04 AK05 AK13 AK14 AL09 4F205 AD04 AD16 AD34 HA03 HA12 HA14 HA22 HA35 HB01 HC16 ACO4 AC15 CA45

Claims (8)

[Claims] 1. A laminate in which a prepreg in which a matrix resin is impregnated with a reinforcing substrate made of glass fiber is laminated, wherein the surface of the glass fiber constituting the reinforcing substrate has an elastic modulus of 50% or less of the matrix resin. A laminate comprising a flexible interface layer formed by coating with a low elasticity resin. 2. The low elasticity resin has a tensile modulus of not more than 1.OGPa or a tensile breaking strain of 20% or more, and the matrix resin has a tensile modulus of not less than 2.0 GPa or a tensile breaking strain. Has a characteristic of 10% or less. 3. The laminate according to claim 1, wherein the low elasticity resin is an isophthalic acid-based resin modified with polypropylene glycol. 4. The method according to claim 1, wherein the adhesion rate of the low elasticity resin to the surface of the glass fiber is 0.1 to 3.5%.
4. The laminate according to any one of items 3. 5. The laminate according to claim 1, wherein the prepreg is disposed at a portion where the laminate is likely to be damaged during the processing. 6. The laminate according to claim 1, wherein the laminate is used as a structural member for corrosion resistance. 7. After forming a flexible interface layer on the surface of the glass fiber constituting the reinforcing substrate, the prepreg is laminated with a matrix resin to perform hand lay-up, RTM,
In a method of molding a laminate by performing press molding, a step of coating a reinforcing substrate made of glass fiber with a resin having a low elastic modulus or a large tensile breaking strain with respect to a matrix resin, and drying the low elastic resin A method of manufacturing a laminate, comprising: a step of impregnating the matrix resin between the reinforcing base materials; and a step of curing the matrix resin together with a low elasticity resin. 8. The reaction of the flexible interface layer does not proceed at room temperature, but increases the adhesiveness by being compatible with the matrix resin.
The method for producing a laminate according to claim 7, wherein after the molding, the curing of the flexible interface layer is started at the time of post-curing.