JP2006249165A - Method for producing resin composition for self-adhesive type prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resin composition for self-adhesive type prepreg holding the compressive strength and tensile strength of the prepreg in a well-balanced state and improving the peel strength between the prepreg and a honeycomb core when applied to a honeycomb panel. <P>SOLUTION: The method for production comprises a first staging step of mixing a plurality of kinds of epoxy resin compositions with a thermoplastic resin and carrying out polymerization and a second staging step of mixing the resultant epoxy resin composition obtained in the first staging step with a new another epoxy epoxy resin composition and a curing agent and carrying out polymerization. The epoxy resin composition obtained in the second staging step is mixed with a new epoxy resin, a solid rubber and the curing agent to afford the final composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a resin composition for a self-adhesive prepreg, and more specifically, when the compressive strength and tensile strength of a prepreg are maintained in a well-balanced state by optimizing the minimum viscosity of the resin and applied to a honeycomb panel. The present invention relates to a method for producing a resin composition for a self-adhesive prepreg, which improves the fluidity of a honeycomb core to improve the peel strength between the honeycomb core and the honeycomb core.

  A prepreg (fiber reinforced composite material) as a molding material obtained by dissolving a matrix resin in a solvent and mixing a curing agent or additive and impregnating cloth, mat, roving, etc. is an aircraft and automobile due to its excellent mechanical properties. Widely used in industrial applications such as

  In particular, honeycomb panels having prepregs as face plates are widely used for aircraft structural materials from the viewpoint of weight reduction. In general, a honeycomb panel is manufactured by adhering a prepreg to both surfaces of a honeycomb core made of a material such as paper, aluminum, aramid, and glass.

  Conventionally, in order to bond a honeycomb core and a prepreg, a film-like adhesive is sandwiched between the honeycomb core and the prepreg and heated to simultaneously cure the prepreg itself and bond the prepreg and the honeycomb core. Has generally been adopted. However, in recent years, from the viewpoint of reducing the weight of the honeycomb core and reducing the molding cost, the honeycomb panel can be formed without using a film-like adhesive by giving the resin used for the prepreg the same characteristics as the adhesive. Research has been conducted on molding (see, for example, Patent Documents 1 and 2).

However, it has the same properties (especially peel strength) as conventional film-like adhesives, and it can satisfy the physical properties (especially tensile strength and compressive strength at high temperature) as the face plate of the honeycomb panel. At present, the development of a resin composition for an adhesive prepreg has not yet been developed.
JP 58-82755 A JP 2001-323046 A

  An object of the present invention is to solve such a conventional problem, and to maintain a good balance between the compressive strength and tensile strength of the prepreg and to improve the peel strength with the honeycomb core when applied to a honeycomb panel. It is providing the manufacturing method of the resin composition for adhesion type prepregs.

  In order to achieve the above object, a method for producing a self-adhesive prepreg resin composition of the present invention comprises a first staging step in which a plurality of epoxy resin compositions and a thermoplastic resin are mixed and polymerized; A second staging step in which another epoxy resin composition and a curing agent mixed with the epoxy resin composition obtained in one staging step are polymerized, and obtained by the second staging step A new epoxy resin, solid rubber and a curing agent are mixed with the epoxy resin composition to obtain a final composition.

  According to this invention, the polymerization process of the epoxy resin composition is made into two stages, and a thermoplastic resin is mixed in the first polymerization process, and a new epoxy is added to the epoxy resin composition obtained by the second polymerization process. Since the final composition was made by adding the resin composition and solid rubber, the minimum viscosity of the epoxy resin obtained as the final composition was optimized by mixing the urethane resin in the first polymerization step, and the compressive strength of the prepreg In addition, the tensile strength is maintained in a well-balanced state, and the fluidity to the honeycomb core when applied to a honeycomb panel is improved, so that the honeycomb wall is sufficiently wetted to form a good fillet, thereby forming the prepreg and the honeycomb core. The peel strength between them can be improved. In addition, since the epoxy resin manufacturing method does not add any special process, workability is not deteriorated.

  The configuration of the present invention will be described in detail below.

  The manufacturing method of the resin composition for self-adhesive prepreg of the present invention is obtained by a first staging step of mixing and polymerizing a plurality of types of epoxy resin compositions and a thermoplastic resin, and the first staging step. A second staging step in which another epoxy resin composition and a curing agent are mixed and polymerized with the obtained epoxy resin composition, and a new staging step is added to the epoxy resin composition obtained by the second staging step. An epoxy resin, solid rubber and a curing agent are mixed to obtain a final composition.

  As described above, by mixing the thermoplastic resin in the first staging step, the epoxy resin as the final composition is optimized for the minimum viscosity, and the compressive strength and tensile strength of the prepreg are maintained in a well-balanced manner. When applied to a panel, the fluidity to the honeycomb core is improved, and the honeycomb wall is sufficiently wetted to form a good fillet, whereby the peel strength between the prepreg and the honeycomb core can be improved. In addition, since the epoxy resin manufacturing method does not add any special process, workability is not deteriorated.

  As the epoxy resin, amine resins, phenols, and epoxy resins having a compound having a carbon-carbon double bond as a precursor are preferably used. Examples of the epoxy resin having an amine as a precursor include various isomers of tetraglycidyldiaminodiphenylmethane, triglycidyl p-aminophenol, and triglycidylaminocresol. Among these, tetraglycidyldiaminodiphenylmethane is preferably used as a resin composition for a prepreg used for a face plate of an aircraft honeycomb panel because it is excellent in heat resistance.

  Examples of the epoxy resin composition having phenol as a precursor include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac. Type epoxy resin, resorcinol type epoxy resin, and the like.

  Further, examples of the epoxy resin having a compound having a carbon-carbon double bond as a precursor include a biphenyl type epoxy resin, a dicyclopentadiene type epoxy resin, and the like. In particular, an epoxy resin having a naphthalene skeleton has water absorption resistance and Since it is excellent in heat resistance, it is preferably used as a resin composition for a prepreg used for a face plate of an aircraft honeycomb panel.

  In this invention, the epoxy resin used as the base material of the resin composition for prepreg may be appropriately mixed with a plurality of types of epoxy resins selected from the various epoxy resins described above. Preferably, a bifunctional epoxy resin and a trifunctional or higher polyfunctional epoxy resin may be blended. Thereby, it can be set as the epoxy resin which has the fluidity | liquidity of resin, and the heat resistance after hardening.

  The thermoplastic resin mixed in the first staging step described above includes carbon-carbon bonds, amide bonds, imide bonds, urethane bonds, ester bonds, ether bonds, carbonate bonds, carbonyl bonds, siloxanes in the main chain. Thermoplastic resins containing bonds, sulfone bonds, etc. are used. Among these, it is particularly preferable to use a urethane resin.

  Furthermore, the blending ratio of the thermoplastic resin may be 18 parts by weight or more, preferably 20 parts by weight or more with respect to 100 parts by weight of the epoxy resin in the first staging step. When the blending ratio of the thermoplastic resin is less than 18 parts by weight, the minimum viscosity of the epoxy resin is lowered, and it becomes difficult to form a good fillet on the honeycomb wall when applied to the honeycomb panel.

  As the solid rubber added after the second staging step in the present invention, an acrylonitrile-butadiene copolymer which is a random copolymer of butadiene and acrylonitrile is preferably used from the viewpoint of compatibility with the epoxy resin. Furthermore, a solid rubber having a functional group is preferably used in order to enhance the adhesion with the epoxy resin. Examples of the functional group include a carboxyl group and an amino group, and a solid acrylonitrile-butadiene rubber containing a carboxyl group is particularly preferable.

  Furthermore, the blending ratio of the solid rubber is preferably 5 to 7 parts by weight with respect to 100 parts by weight of the epoxy resin in the final composition. As a result, it is possible to increase the minimum viscosity of the resin and prevent tough resin outflow during molding to ensure toughness and improve adhesiveness. Furthermore, the compressive strength and tensile strength of the prepreg can be improved with a better balance. If the blending ratio of the solid rubber is less than 5 parts by weight, the minimum viscosity of the resin will be too low to prevent excessive resin outflow at the time of molding and the adhesiveness will be reduced. If it exceeds 7 parts by weight, the minimum viscosity of the resin will be high. It becomes too much and resin outflow at the time of molding cannot be obtained.

  The curing agent used in the present invention is not particularly limited as long as it is a compound having an active group capable of reacting with an epoxy group. Preferably, a compound having an amino group, an acid anhydride group, or an azide group is suitable. More specifically, dicyandiamide, diaminodiphenylmethane, various isomers of diaminodiphenylsulfone, aminobenzoic acid esters, various acid anhydrides, phenol novolac resin, cresol novolac resin, polyphenol compound, and the like can be mentioned.

  As described above, the method for producing a resin composition for a self-adhesive prepreg according to the present invention comprises a two-stage polymerization process for an epoxy resin composition and a urethane resin mixed in the first polymerization process. Since a new epoxy resin composition and solid rubber were added to the epoxy resin composition obtained in the polymerization step to obtain a final composition, the epoxy obtained as the final composition by mixing the urethane resin in the first polymerization step The minimum viscosity of the resin is optimized and the compressive strength and tensile strength of the prepreg are maintained in a well-balanced manner, and a good fillet is formed on the honeycomb wall when applied to a honeycomb panel, and the peel strength between the honeycomb core is increased. Since it improves, it is preferably used particularly for a face panel of an aircraft honeycomb panel.

The epoxy resin according to the present invention (Example 1) and the comparative epoxy resin (comparison) comprising the “final composition” shown in the middle part of the table, with different compositions, weights and polymerization steps constituting the epoxy resin as shown in Table 1. While producing Examples 1-3), 4 types of prepregs were produced by the method shown below using each epoxy resin. In Comparative Example 2, the step of polymerizing the epoxy resin is one stage, and in Comparative Example 3, the step of polymerizing the epoxy resin is not included.
[Preparation of prepreg]
Each resin composition was applied onto a release paper using a reverse roll coater to prepare a resin film having a resin basis weight of 65 g / m ² . Next, the two resin films were superposed on both sides of a plain weave carbon fiber (T300-3K, manufactured by Toray Industries, Inc.) and heated and pressed to impregnate the carbon fiber with the resin composition. After impregnating the resin composition, the resin film was peeled off, and a polyethylene film was placed on one side of the peeled surface and wound up to obtain a prepreg sheet.

  The minimum viscosity of the five types of resin compositions described above is measured by the following method, and the prepreg impregnated with these five types of resin compositions is measured for porous compressive strength, plane tensile strength and peel strength by the following test methods. Measurements were made and the results are shown in Table 1.

[Minimum viscosity]
Using a dynamic viscoelastic device (ARES-II) manufactured by Rheometrics,
The minimum viscosity (Pa · s) of each resin was measured under the conditions of a heating rate of 2.8 ° C./min, a frequency of 10 rad / sec, and a strain of 1% by the G method (diameter 25.4 mm). Are listed in Table 1.

[Perforated compressive strength]
Sixteen prepregs made of each resin are laminated and placed in a bag, which is heated in an autoclave at 180 ° C. for 2 hours (heating rate: 2.8 ° C./min) and cured to form a molded plate. Produced. During this time, the inside of the autoclave was pressurized to 0.32 MPa with compressed air.

  The obtained molded plate was processed into a predetermined size to produce each test piece, and the test conditions were (1) dry state at 23 ° C. and (2) 93 ° C. The perforated compressive strength (MPa) of each test piece in the moisture absorption state was measured. In addition, as each test piece in a hygroscopic state, the test piece taken out after being immersed in warm water of 70 ° C. for 2 weeks was used.

[Plane tensile strength]
The molded plate used in the measurement of the above [Perforated compressive strength] is processed into predetermined dimensions to produce each test piece, and each test at 23 ° C. (dry state) according to MIL-STD-401. The plane tensile strength (MPa) of the piece was measured.

[Peel strength]
Two prepregs made of each resin are laminated and placed on both sides of a honeycomb core (Nomex SAH-1 / 8-8.0, manufactured by Showa Aircraft Industry Co., Ltd.) and placed in a bag. Was heated in an autoclave at 180 ° C. for 2 hours (heating rate: 2.8 ° C./min) and cured to prepare a honeycomb panel. During this time, the inside of the autoclave was pressurized to 0.32 MPa with compressed air.

The obtained honeycomb panel was processed into a predetermined size, and the peel strength (lb-in / 3 in) of each test piece at 23 ° C. (dry state) was measured in accordance with ASTM D1781.

From the property evaluation results in Table 1, the epoxy resin composition of Example 1 was subjected to two-stage staging after mixing the thermoplastic resin. As a result, the epoxy resin composition showed higher viscosity than the lowest viscosity of Comparative Examples 1 to 3, and the prepreg While the porous compressive strength and the plane tensile strength of each were equal, the peel strength when applied to a honeycomb panel was high, and excellent self-adhesiveness was exhibited. On the other hand, the epoxy resin composition which performed the staging process without mixing the thermoplastic resin shown in Comparative Examples 1 to 3, and the epoxy resin composition which has not been subjected to the staging process without mixing the thermoplastic resin The peel strength of the honeycomb panel was low, and sufficient self-adhesion was not recognized.

Claims (5)

  A first staging step of mixing and polymerizing a plurality of types of epoxy resin compositions and thermoplastic resins, another epoxy resin composition newly added to the epoxy resin composition obtained by the first staging step, and A second staging step in which a curing agent is mixed and polymerized, and a new epoxy resin, a solid rubber and a curing agent are mixed with the epoxy resin composition obtained by the second staging step to obtain a final composition. A method for producing a self-adhesive prepreg resin composition to be obtained.   The method for producing a resin composition for self-adhesive prepreg according to claim 1, wherein the blending ratio of the thermoplastic resin is 18 parts by weight or more with respect to 100 parts by weight of the epoxy resin in the first staging step.   The method for producing a resin composition for self-adhesive prepreg according to claim 1, wherein the thermoplastic resin is a urethane resin.   4. The method for producing a resin composition for self-adhesive prepreg according to claim 1, wherein the solid rubber is acrylonitrile-butadiene rubber containing a carboxyl group. The method for producing a resin composition for self-adhesive prepreg according to any one of claims 1 to 4, wherein a blending ratio of the solid rubber is 5 to 7 parts by weight with respect to 100 parts by weight of the epoxy resin in the final composition. .