JP2016175970A - Prepreg and laminate sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg that can, while maintaining a high fire retardancy for formed product, achieve an excellent performance in tackiness and adhesiveness with honeycomb material or the like, and to provide a laminate sheet using the same.SOLUTION: Provided is a prepreg, and a laminate sheet using the same, characterized in comprising at least the following constitutive elements [A], [B], [C] and [D], and containing a thermoplastic resin [B] by 1 to 10 pts.mass per 100 pts.mass of a phenolic resin [A], and in which, characterized, the tack force measured by surface pressure bonding method in JIS K 7071 at temperature of 23°C and relative humidity of 50% is 1 N or more and 8 N or less. [A] a phenolic resin, [B] a thermoplastic resin having a weight average molecular weight of 5,000 to 150,000, [C] a thixotropic agent, [D] a reinforcing fiber fabric.SELECTED DRAWING: None

Description

  The present invention relates to a prepreg suitably used for an interior panel or the like that requires flame retardancy, and a laminate using the prepreg.

  2. Description of the Related Art Conventionally, sandwich panels featuring light weight and high rigidity have been widely used in applications such as interior panels that require flame retardancy or inner wall materials of buildings. A conventional sandwich panel has a fiber reinforced plastic (hereinafter abbreviated as FRP) or metal on both or one side of a light-weight core material such as a honeycomb material made of paper, metal, or a resin foam sheet. A skin material such as a plate made of metal is pasted. When manufacturing such a sandwich panel, a method of using a sheet-like film adhesive is generally used for bonding the skin material and the core material. And when the bending load acts on the sandwich panel, the strength of the skin material cannot be fully utilized unless the adhesive strength between the skin material and the core material is sufficient. In addition, when a honeycomb material or a foam core material is used, since the bonding area is small, the resin flow is controlled so that a resin reservoir portion called a fillet is formed at the contact portion between the skin material and the core material. Need to be added. For this reason, as conventional film adhesives, epoxy resins having excellent adhesive strength and a large degree of freedom of modification have been widely used.

  However, the use of such a film adhesive causes an increase in material cost and molding cost in the manufacture of a sandwich panel, which is not preferable from the viewpoint of manufacturing.

  For this reason, so-called self-adhesive prepregs have been developed in which the resin content of the prepreg is increased and the resin from the prepreg wraps around the bonding surface with the honeycomb material during molding, and also serves as an adhesive with the skin material. It was. However, most of the resins used for this type of prepreg are also epoxy resins in terms of mechanical properties and adhesive strength.

  On the other hand, in recent years, from the viewpoint of safety at the time of fire or the like, flame retardant regulations for materials used for interiors in places where a large number of people gather are being strengthened. This movement starts with aircraft interior materials, and gradually spreads to interior panels of vehicles and the inner wall materials of buildings. For this reason, in aircraft interior materials, not only prepregs of epoxy resins that have been widely used until now, but also prepregs using flame retardant epoxy resins in which halogen is introduced into the epoxy resin composition, emit smoke during combustion. However, it has become difficult to use in terms of heat generation, and development of alternative materials has become necessary.

  As a result, phenolic resins that have been known for good flame retardancy have been used for a long time. However, this phenol resin is certainly superior to the epoxy resin in its flame retardant properties and has the best flame retardant properties as a thermosetting resin. However, since it is a so-called brittle resin, the strength of the reinforcing fiber cannot be fully expressed in the skin material, and the adhesive strength with the core material is low. In other words, when phenol resin is used, its flame retardancy is good, but the strength and adhesive strength are low, and extra reinforcing fibers are required to obtain the same strength as epoxy resin, making it a sandwich panel The light weight effect could not be sufficiently achieved. Furthermore, since the phenol resin has insufficient adhesive force, it is difficult to obtain a so-called cocure type prepreg even if the resin content in the prepreg is increased.

  As a method for increasing the adhesive force between the prepreg and the core material, a method of adding a thermoplastic resin to a matrix resin is known (for example, Patent Document 1). However, since the resin used in Patent Document 1 has a low viscosity and is not imparted with thixotropy, when it is a sandwich panel, the prepreg as a skin material and the honeycomb core as a core material on the upper and lower surfaces. Differences in adhesive strength were likely to occur.

  In addition, when forming a plate with a complicated shape that is not a flat plate, it is necessary to follow the shape of the mold while applying the prepreg to the mold during lamination work, but if the tackiness is too low, it is difficult to apply it to the mold. On the other hand, if the tackiness is too high, it is difficult to correct by peeling off, and the prepreg lamination work becomes complicated. The phenol resin is generally a resin having a low tack property when used as a prepreg and inferior in the lamination workability.

  Tack property changes also with the amount of residual solvent in an additive or a prepreg (for example, patent document 2). In Patent Document 2, the thermoplastic resin added to the phenolic resin has a weight average molecular weight of 300,000 to 3,000,000, which is a high molecular weight, and when such a high molecular weight resin is added, the tackiness tended to decrease rapidly. .

JP-A-4-306253 WO99 / 28383

  Accordingly, an object of the present invention is to provide a prepreg capable of expressing performance excellent in tackiness and adhesion to a honeycomb material, etc., while maintaining high flame retardancy of a molded product, and a laminate using the prepreg It is in.

As a result of various studies to solve the above problems, the present inventors have found the following prepreg. That is, the prepreg according to the present invention comprises at least the following components [A], [B], [C] and [D], and 1 part of the thermoplastic resin [B] is contained in 100 parts by mass of the phenol resin [A]. The tack force measured by the surface pressure bonding method in JIS K7071 is 1N or more and 8N or less at a temperature of 23 ° C. and a relative humidity of 50%.
[A] phenol resin [B] thermoplastic resin having a weight average molecular weight of 50,000 to 150,000 [C] thixotropic agent [D] reinforced fiber fabric

  In the prepreg according to the present invention, the thermoplastic resin [B] is, for example, at least one thermoplastic selected from polyvinyl formal, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol, and polyethylene glycol. Made of resin.

  Further, as the thixotropic agent [C], various inorganic particles can be used, and silica is particularly preferably used. The content of the thixotropic agent [C] is preferably in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the phenol resin [A].

In addition, the prepreg according to the present invention preferably has a maximum heat generation rate of 110 kW / m ² or less measured according to ISO 5660-1: 2002.

  The present invention also provides a laminated plate obtained by laminating and bonding a prepreg and a substrate having a hole extending in the thickness direction, wherein the prepreg is the prepreg according to the present invention as described above. .

  In the laminated board according to the present invention, a honeycomb material can be used as the base material having the holes extending in the thickness direction.

  ADVANTAGE OF THE INVENTION According to this invention, the prepreg excellent in the flame retardance, the tack property with favorable handleability at the time of shaping | molding, and the self-adhesiveness with a core material, and a laminated board using the same can be provided.

Hereinafter, the present invention will be described in detail together with preferred embodiments.
The prepreg according to the present invention comprises at least the following components [A], [B], [C] and [D], and 1 to 10 parts of the thermoplastic resin [B] in 100 parts by mass of the phenol resin [A]. The tack force measured by the surface pressure bonding method in JIS K7071 is 1N or more and 8N or less at a temperature of 23 ° C. and a relative humidity of 50%, including mass parts.
[A] phenol resin [B] thermoplastic resin having a weight average molecular weight of 50,000 to 150,000 [C] thixotropic agent [D] reinforced fiber fabric

  Generally, the phenol resin [A] is phenol, alkylphenol such as cresol or xylenol, or various phenols such as halogenated alkylphenol in which a part of the benzene ring of the alkylphenol is substituted with a halogen atom, formaldehyde, acetaldehyde, It is synthesized by a condensation reaction with aldehydes such as furfural. Phenol resins are roughly classified into two types depending on the catalyst used during the synthesis, one of which is a novolac type phenol resin synthesized by an acidic catalyst, and the other is a resol type phenol resin synthesized by a basic catalyst. Both of these can be used in the present invention. The novolak-type phenol resin requires an amine-based curing agent such as hexamethylenetetramine as a catalyst at the time of heat curing, but the resol-type phenol resin is cured only by heating. If an acid catalyst is added, the resol type phenol resin can be cured at a lower temperature. Ammonia resol type phenol resins and benzoxazine type phenol resins are also preferred. The benzoxazine-type phenol resin is a resin having an oxazine ring synthesized from phenols, aldehydes, and amines. Since it is cured by ring-opening polymerization, there is no generation of condensed water, and voids are hardly generated in the molded product. Therefore, it is preferable to obtain a high-strength molded body. If bisphenol is selected as the phenol, it becomes bifunctional. As the raw material bisphenol, various structures such as bisphenol A, bisphenol F, bisphenol S, biphenyl, dihydroxybenzophenone, and diphenylfluorene can be used. Polycyclic phenols such as naphthol and naphthodiol can also be used as a raw material. Many phenolic resins are dissolved or dispersed in a solvent or water, but the higher the solid content concentration, the less likely voids are formed in the molded product, which is preferable for the present invention. In particular, the solid content is preferably 70% by weight or more, more preferably 80% by weight or more.

  The thermoplastic resin [B] used in the present invention needs to have a weight average molecular weight of 50,000 to 150,000. When the weight average molecular weight of the thermoplastic resin [B] is in the range of 50,000 to 150,000, it is possible to achieve both adhesion to the honeycomb material, dispersibility to the phenolic resin, and tackiness.

  When the weight average molecular weight of the thermoplastic resin [B] is less than 50,000, the effect of improving the adhesion to the honeycomb material tends to be reduced. On the other hand, when the weight average molecular weight of the thermoplastic resin [B] exceeds 150,000, the dispersibility with respect to the phenolic resin is lowered, and it becomes difficult to produce a product having stable performance. In addition, when a high molecular weight thermoplastic resin is added, tackiness is greatly reduced with a small addition.

  Moreover, content of thermoplastic resin [B] needs to be 1-10 mass parts with respect to 100 mass parts of phenol resin [A]. When the amount is less than 1 part by mass, the effect of increasing the adhesion to the honeycomb core cannot be obtained. Conversely, when the amount exceeds 10 parts by mass, the tackiness is lowered and the flame retardancy is deteriorated.

  In addition, as the thermoplastic resin [B], for example, at least one thermoplastic resin selected from polyvinyl formal, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol, and polyethylene glycol is used. Is preferred. These thermoplastic resins are characterized by not only improving adhesion to the honeycomb material but also having good compatibility or dispersibility with the phenol resin.

As the thixotropic agent [C], for example, talc, aluminum silicate, silica (particularly particulate silica), calcium carbonate, mica, montmorillonite, smectite, carbon black, silicon carbide, alumina hydrate, etc. are used. be able to. These inorganic particles have a great effect of rheology control, that is, thickening and thixotropy imparting effects. Among these, it is known that fine particulate silica has a great thixotropic effect when added to a resin composition. When the thixotropic property is high, in the case of adopting the configuration of the honeycomb sandwich panel, it is possible to reduce the phenomenon that the resin in the fillet portion that bonds the upper prepreg and the honeycomb core hangs down. In addition, the temperature dependence of the viscoelastic function of the resin composition is reduced, the handling property is not easily deteriorated even when the working environment temperature in which the prepreg is handled is changed, and the change in tackiness over time due to leaving the prepreg is reduced. It is preferable because the surface smoothness of the skin panel, which is a cured product, is improved, and the self-adhesiveness to the honeycomb core is excellent. As fine particle silica having silicon dioxide as a basic skeleton, for example, those having an average primary particle diameter in the range of 5 to 40 nm are commercially available under the trademark of Aerosil (manufactured by Nippon Aerosil Co., Ltd.). It is preferable that the primary particle diameter is as fine as 40 nm or less in order to give a sufficient thickening effect. The particle diameter is evaluated with an electron microscope. The specific surface area is preferably in the range of 50 to 400 m ² / g. In general, silica whose silica surface is covered with silanol groups is used. However, it is important to use hydrophobic fine-particle silica in which the hydrogen of the silanol group is substituted with methyl group, octyl group, dimethylsiloxane, etc. It is more preferable from the viewpoints of effect, stabilization of thixotropic properties, and improvement of mechanical properties represented by water resistance and compression strength of the molded product. Addition of organic particles may be performed as long as the heat resistance is not lowered.

  Moreover, it is preferable that content of thixotropic agent [C] is 0.1-5 mass parts with respect to 100 mass parts of phenol resin [A]. When the amount is less than 0.1 parts by mass, the effect of imparting thixotropy is small. Conversely, when the amount exceeds 5 parts by mass, it is difficult to impregnate the reinforcing fibers during prepreg production. A more preferable addition amount is 0.1 to 3 parts by mass, and further preferably 0.2 to 2 parts by mass.

  Carbon fiber, graphite fiber, aramid fiber, glass fiber, etc. can be used as the reinforcing fiber of the reinforcing fiber fabric [D] that can be used for the prepreg according to the present invention. The form of the reinforcing fiber fabric [D] is not particularly limited, and any form of fabric can be used.

  The prepreg according to the present invention essentially comprises the above-described components [A], [B], [C], and [D]. May contain various additives such as thermosetting resins other than those described above, fillers, anti-aging agents, flame retardants, pigments and the like.

  In the prepreg according to the present invention, the content of the matrix resin is preferably 30 to 50% by weight, more preferably 35 to 45% by weight. If the ratio of the matrix resin in the prepreg is within such a range, the self-adhesiveness of the prepreg is improved, the workability and the appearance quality are improved, and the mechanical properties when molded as a fiber-reinforced composite material are sufficient. Can be demonstrated.

  The resin composition in the prepreg according to the present invention is usually used as a solution, but may be used as a suspension, or may be used without a solvent, that is, by hot melt. As the solvent, an organic solvent is generally used, but an aqueous medium may be used.

  Examples of the organic solvent used in the present invention include alcohols, ethers, ketones, esters, amides, or a mixed solvent of two or more thereof. Specifically, for example, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, diethyl ether, tetrahydrofuran, ethyl carbitol, butyl carbitol, ethyl acetate, ethyl carbitol And butyl carbitol acetate, dimethylformamide, dimethyl sulfoxide, or a mixed solvent of two or more thereof.

  By changing the amount of the organic solvent remaining in the prepreg, the tackiness of the prepreg can be controlled.

Regarding the flame retardancy, considering that it is used as a flame retardant application, the maximum heat generation rate measured in accordance with ISO 5660-1: 2002 is preferably 110 kW / m ² or less in a flat plate formed by stacking two prepregs. .

  When forming a plate with a complex shape that is not a flat plate, it is necessary to keep the prepreg along the shape of the die while laminating, but if the tackiness is too low, it is difficult to attach to the die. If the tackiness is too high, it is difficult to correct by peeling off, and the prepreg lamination work becomes complicated. In order to achieve tackiness with excellent workability, the measured tension needs to be 1 to 8 N in accordance with the method described in JIS K7071 Method B (surface pressure bonding method).

  With respect to the adhesive strength of the sandwich panel, the climbing drum peel strength measured according to ASTM D1781-76 is preferably 20 N · in / 3 inches or more on the upper and lower skin surfaces, respectively. If it is smaller than 20 N · in / 3 in, the skin surface and the honeycomb core may be separated.

  In addition, in the sandwich panel, the closer the climbing drum peel strength between the upper and lower skin surfaces and the honeycomb material (honeycomb core) is, the better the sandwich panel as a product. The difference between the upper and lower climbing drum peel strength is preferably 10% or less.

  As the honeycomb material, a honeycomb material made of aramid paper impregnated with a phenol resin is particularly preferably used because it can form a high-strength structure while being lightweight. A cell size in the range of 3 to 19 mm is generally used. In addition, an aluminum honeycomb, a glass fiber reinforced plastic (GFRP) honeycomb, a graphite honeycomb, a paper honeycomb, or the like may be used.

  As a method for forming a honeycomb sandwich panel, vacuum bag molding, autoclave molding using a vacuum bag, press molding, or the like can be used. Autoclave molding is particularly preferable for obtaining a high-performance honeycomb sandwich panel. On the other hand, press molding is more preferable for shortening the molding cycle.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Examples 1 to 4]
(1) Preparation of prepreg [A], [B] and [C] whose product names are listed below were added and mixed in methanol as a solvent. Table 1 shows the components of the resin composition, the blending amount (parts by mass), and the evaluation results. After impregnating the obtained resin composition with glass cloth [D] (trade name: S325 A 103H (manufactured by Unitika)) which is a reinforced fiber fabric, a temperature gradient is continuously provided in the range of 80 ° C to 140 ° C. For 4 minutes to obtain a prepreg having a resin adhesion amount of 41% by weight.
[A] Phenol Made by Gunei Chemical Industry Co., Ltd. (trade name: REGI-TOP PL-3261)
[B] Thermoplastic resin Sekisui Chemical Co., Ltd. (trade name: ESREC BM-S (polyvinyl butyral, weight average molecular weight: 53,000))
[C] Thixotropic agent: Nippon Aerosil Co., Ltd. (trade name: “AEROSIL” (registered trademark) 200)

(2) Molding of sandwich panel Two prepregs were bonded to both sides of Nomex honeycomb SAH1 / 8-1.8 (manufactured by Showa Aircraft Industry Co., Ltd.), and a honeycomb sandwich panel was molded by an autoclave. Curing is performed at 1 ° C./min up to 80 ° C., held at the same temperature for 1 hour, then heated at 1 ° C./min to 150 ° C. and held at the same temperature for 1.5 hours in an autoclave. went. The pressure during molding was 0.2 MPa, and the bag was evacuated. This sandwich panel was tested for adhesion.

(3) Formation of flat plate Two prepregs were stacked and a flat plate was formed in an autoclave. The curing conditions were the same as (2). A flame retardancy test was performed on this flat plate.

(4) Tack property test The tack property of the prepreg was tested using EZ-SX manufactured by Shimadzu Corporation according to the method described in JIS K7071 Method B (surface pressure bonding method). In this method, a cubic rubber having a side of 10 mm is pressed against the prepreg with a force of 5 N for 30 seconds, and then the maximum load required when the rubber is lifted straight and separated from the prepreg is measured.

(5) Adhesion test In the honeycomb sandwich panel formed by the method described in (2) above, self-adhesion between the skin panel and the honeycomb core is in accordance with ASTM D1781-76, using an Instron 5565 type universal testing machine, Climbing drum peel strength was measured. The test piece size was 304.8 mm long × 76.2 mm wide.

(6) Flame Retardancy Test The flame retardant test was conducted according to ISO 5660-1: 2002 using a CONE Calimeter III manufactured by Toyo Seiki Seisakusho Co., Ltd. The test body used the board which cut | disconnected the flat plate shape | molded by the method of said (3) in the size of 100 mm x 100 mm.

[Comparative Examples 1-5]
Table 2 shows the components, blending amounts and evaluation results of the resin composition as a comparative example. According to Table 2, it produced similarly to the Example except having changed the component and the compounding quantity.
The following resins were used as thermoplastic resins other than the thermoplastic resin [B] defined in the present invention (Comparative Examples 4 and 5).
-Polyethylene glycol 2,000 (polyethylene glycol, weight average molecular weight: 2,000) manufactured by Wako Pure Chemical Industries, Ltd.
-Pure Chemical Co., Ltd. polyvinyl pyrrolidone K-90 (polyvinyl butyral, weight average molecular weight: 360,000)

  In Comparative Example 1, the adhesiveness is lowered, and in Comparative Example 2, the flame retardancy is deteriorated. Thus, from the comparison of Examples 1 to 3 and Comparative Examples 1 and 2, if the addition amount of polyvinyl butyral is in the range of 1 to 10 parts by mass, the flame retardancy, the adhesiveness to the honeycomb core and the tackiness are excellent. It can be seen that a prepreg can be produced.

  From the comparison between Examples 2 and 4 and Comparative Example 3, by adding silica (Aerosil), it is possible to substantially equalize the adhesive force between the upper surface and the lower surface with respect to the adhesiveness to the honeycomb core in the sandwich panel. I understand that. Moreover, it turns out that it is excellent also about flame retardance and tackiness other than adhesiveness.

  From Comparative Examples 4 and 5, the prepreg and the sandwich panel to which the thermoplastic resin not suitable for the present invention is added cannot obtain satisfactory characteristics.

  Comparative Example 4 in which polyethylene glycol having a molecular weight of 20,000 was added resulted in low adhesion to the honeycomb core.

  In Comparative Example 5 in which polyvinylpyrrolidone having a molecular weight of 360,000 was added, the compatibility between polyvinylpyrrolidone and phenol was poor, and it was difficult to produce a uniform prepreg in appearance. The adhesion between the honeycomb sandwich panel and the honeycomb core also differs greatly in the adhesive strength between the upper and lower surfaces, making it difficult to produce a honeycomb sandwich panel having stable physical properties.

  Since the phenolic prepreg of the present invention has good flame retardancy, adhesion to a honeycomb core, and tackiness, it can be used for aircraft materials, sports / leisure use, vehicles / ships, civil engineering / architecture use.

Claims (7)

It consists of at least the following components [A], [B], [C], and [D], 1 to 10 parts by mass of the thermoplastic resin [B] in 100 parts by mass of the phenol resin [A], and a temperature of 23 ° C. A prepreg characterized by having a tack force of 1N or more and 8N or less measured by a surface compression method in JIS K7071 at a relative humidity of 50%.
[A] phenol resin [B] thermoplastic resin having a weight average molecular weight of 50,000 to 150,000 [C] thixotropic agent [D] reinforced fiber fabric   The prepreg according to claim 1, wherein the thermoplastic resin [B] is at least one thermoplastic resin selected from polyvinyl formal, polyvinyl acetal, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol, and polyethylene glycol.   The prepreg according to claim 1 or 2, wherein the thixotropic agent [C] is silica.   The prepreg according to any one of claims 1 to 3, wherein the thixotropic agent [C] content is in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the phenol resin [A]. The prepreg according to any one of claims 1 to 4, wherein a maximum heat generation rate measured in accordance with ISO 5660-1: 2002 is 110 kW / m ² or less.   A laminated board obtained by laminating and bonding a prepreg and a substrate having a hole extending in the thickness direction, wherein the prepreg is the prepreg according to any one of claims 1 to 5.   The laminate according to claim 6, wherein the base material having holes extending in the thickness direction is made of a honeycomb material.