WO2020137945A1

WO2020137945A1 - Resin composition, fiber-reinforced plastic molding material, and molded article

Info

Publication number: WO2020137945A1
Application number: PCT/JP2019/050297
Authority: WO
Inventors: 涼丞原子; 浩之 ▲高▼橋
Original assignee: 日鉄ケミカル＆マテリアル株式会社
Priority date: 2018-12-26
Filing date: 2019-12-23
Publication date: 2020-07-02
Also published as: JPWO2020137945A1; TW202033659A

Abstract

The present invention provides: an FRP molding material which is capable of suppressing the problem of changes in mechanical characteristics in a high temperature environment by means of a crosslinking reaction, while maintaining good moldability that is a characteristic of phenoxy resins, and which enables the achievement of an FRP molded article that has a heat resistance high enough for use in a harsh environment and excellent mechanical strength at room temperature and in a hot environment; and a method for producing this FRP molding material.　A resin composition which is used, as a fiber-reinforced plastic molding material, together with a reinforcing fiber base material, and which is characterized by containing, as essential ingredients, (A) a phenoxy resin, (B) a maleic acid anhydride copolymer serving as a crosslinking agent and (C) a curing catalyst, and is also characterized in that: the maleic acid anhydride copolymer (B) has a weight average molecular weight of 100,000 or less and an acid value of 100-400 KOH-mg/g; and the components are blended so that the molar ratio of the secondary hydroxyl groups of the phenoxy resin (A) to the acid anhydride groups of the maleic acid anhydride copolymer (B) is from 1/0.1 to 1/1.6.

Description

Resin composition, fiber-reinforced plastic molding material and molded article

The present invention relates to a resin composition having a good impregnation property into a reinforced fiber base material and a good moldability, a fiber reinforced plastic molding material using the composition as a matrix resin, and a molded product thereof.

Fiber-reinforced plastic (FRP) material, which is a composite material of glass fiber or carbon fiber and plastic, is lightweight, has high strength and high rigidity, and is used for the industrial robots from the housing of electronic devices such as notebook PCs and tablets. Its applications are being applied to consumer equipment, industrial equipment, and automobile fields such as arms for automobiles, reinforcing materials for building structures, structural members such as automobile back doors and pillars.

A general FRP material is made by impregnating a base material made of reinforcing fibers with a liquid thermosetting resin such as an epoxy resin as a matrix resin, and curing and molding. However, when a thermosetting resin is used as the matrix resin, it is generally essential to use a curing agent together, so while the storage load of such a mixture is large, the curing time is long and the productivity is low. There is a strong demand for improvement.

Although the application of thermoplastic resin as a matrix resin is also under consideration, engineering plastics such as polyamide have a high melting point and high viscosity, making it difficult to impregnate a reinforced fiber base material or requiring a high temperature process for molding. There is a problem such as.

On the other hand, a thermoplastic resin that melts at a relatively low temperature, such as a phenoxy resin, has no problem in terms of processability, but it has poor heat resistance as an FRP material and has a problem of compatibility with high-temperature processes such as baking coating.

Therefore, Patent Documents 1 and 2 propose a method of increasing the glass transition temperature by a crosslinking reaction utilizing a hydroxyl group in the side chain of a phenoxy resin. This is due to the three-dimensional cross-linking of the phenoxy resin utilizing the esterification reaction between the hydroxyl group and the acid anhydride group, but the aromatic dianhydride used as the cross-linking agent easily absorbs moisture, depending on the storage environment conditions. Has a problem that the reactivity of the crosslinking reaction varies. Further, it is recommended to carry out post cure for 30 to 60 minutes to complete the crosslinking reaction, so that the takt time at the time of molding becomes long and it is difficult to reduce the manufacturing cost.

Further, as a resin composition utilizing a cross-linking reaction between an acid anhydride and a hydroxyl group, an adhesive resin composition obtained by blending a maleic anhydride-modified styrene resin, a naphthalene epoxy resin, and a latent curing agent into a bisphenol F type epoxy resin as in Patent Document 3. Example 9 discloses a blend of a bisphenol F-type phenoxy resin, a maleic anhydride-modified styrene resin, and an imidazole curing agent.
However, Patent Document 3 discloses a conductive resin composition for a circuit board material, which uses a bisphenol F-type phenoxy resin for the purpose of exhibiting flexibility and promoting a curing reaction of an epoxy resin, and a styrene copolymer. Is used for adjusting viscosity and suppressing bubbles, and the purpose of combining the two is to prevent contact between the latent curing agent and the epoxy resin at room temperature. In addition, the Tg of the obtained resin composition is 130° C. or lower, and the necessary physical properties such as melt viscosity necessary for use as a matrix resin of FRP are not disclosed at all.

Further, Patent Document 4 also discloses a resin composition for an adhesive, which is a mixture of maleic anhydride-modified polypropylene and a phenoxy resin. However, the phenoxy resin is a compound containing modified polypropylene as a main component at about 20 wt %. However, the evaluation was made only on the adhesive strength, and neither the improvement of Tg nor the physical properties necessary for the matrix resin of FRP were disclosed.

WO2014/157132 WO2016/152856 Japanese Patent Laid-Open No. 9-143445 JP, 2014-218633, A

An object of the present invention is an FRP molding material capable of suppressing changes in mechanical properties under a high temperature environment, which is a problem due to a crosslinking reaction, while having a good moldability which is a characteristic of a phenoxy resin. However, it is an object of the present invention to provide an FRP molding material capable of obtaining a FRP molding having high heat resistance that can be used and excellent mechanical strength at room temperature and hot and a manufacturing method thereof.

The present inventors have conducted extensive studies to solve the above problems, and when the fiber-reinforced base material is a continuous fiber, use a thermoplastic phenoxy resin as a main component and combine a specific cross-linking agent. The inventors have found that the above problems can be solved by using a resin composition, and have completed the present invention.

That is, the present invention is a resin composition used together with a reinforced fiber base material as a material for molding a fiber reinforced plastic, comprising a phenoxy resin (A) and a maleic anhydride copolymer (B) as a cross-linking agent. The curing catalyst (C) is contained as an essential component, the weight average molecular weight of the maleic anhydride copolymer (B) is 100,000 or less, and the acid value is 150 to 400 KOH-mg/g, and the phenoxy resin (A) is A resin composition characterized in that the secondary hydroxyl group and the acid anhydride group of the maleic anhydride copolymer (B) are mixed in a molar ratio of 1/0.1 to 1/1.6. It is a thing.

The resin composition may contain an epoxy resin (D), and the crosslinked or cured resin composition preferably has a glass transition temperature (Tg) of 160° C. or higher.

The present invention is also a fiber-reinforced plastic molding material in which at least a part of a reinforced fiber base material is coated or impregnated with the above resin composition.

Furthermore, the present invention is also a fiber-reinforced plastic molded product obtained by heat-molding this fiber-reinforced plastic molding material.

The resin composition of the present invention is used as a matrix resin for a fiber-reinforced plastic molding material, and since the reinforced fiber base material is satisfactorily impregnated, voids and the like are formed inside the molded body when this is used as a molded body. Is less likely to occur. Therefore, there is an effect that the mechanical properties of the molded body can be maintained well. Further, as a fiber-reinforced plastic molding material, since the matrix resin of the molding material is composed of a resin composition containing a thermoplastic phenoxy resin as a main component, it is flexible and can be shaped into various shapes. In addition to its characteristics, it has excellent adhesiveness to different materials. Further, the molded product can have a good external appearance, excellent heat resistance, and low water absorption.

Hereinafter, the present invention will be described in detail.
The resin composition used together with the reinforcing fiber as the FRP molding material of the present invention is a solvent-free room temperature system containing phenoxy resin (A), maleic anhydride copolymer (B) and curing catalyst (C) as essential components. It is a solid phenoxy resin composition. Further, the epoxy resin (D) may be contained.

The phenoxy resin (A) used as an essential component of the resin composition of the present invention is solid at room temperature and exhibits a melt viscosity of 4000 Pa·s or less in any of the temperature ranges of 160 to 280°C. .. The melt viscosity is preferably 3500 Pa·s or less, more preferably 3000 Pa·s or less. If the melt viscosity exceeds 4000 Pa·s in any temperature range from 160 to 280°C, the fluidity of the phenoxy resin during molding will deteriorate, and the phenoxy resin will not fully spread into the fiber substrate, causing voids. However, the mechanical properties of the molded product deteriorate.

The phenoxy resin is a thermoplastic resin obtained by a condensation reaction between a dihydric phenol compound and epihalohydrin or a polyaddition reaction between a dihydric phenol compound and a difunctional epoxy resin, which is a conventionally known method in a solution or without a solvent. Can be obtained at The average molecular weight is usually 10,000 to 200,000 as a mass average molecular weight (Mw), preferably 20,000 to 100,000, and more preferably 30,000 to 80,000. If the Mw is too low, the strength of the molded article will be poor, and if it is too high, the workability and workability will tend to be poor. The Mw is a value measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve.

The hydroxyl equivalent (g/eq) of the phenoxy resin is usually 50 to 1000, preferably 50 to 750, particularly preferably 50 to 500. If the hydroxyl group equivalent is too low, the water absorption rate increases due to an increase in the number of hydroxyl groups, and there is a concern that the mechanical properties will deteriorate. If the hydroxyl group equivalent is too high, the number of hydroxyl groups is small, so that the wettability with the carbon fibers constituting the reinforcing fiber substrate is lowered, and even if a crosslinking agent is used, the crosslink density is low and mechanical properties are not improved. Here, the hydroxyl group equivalent as used herein means a secondary hydroxyl group equivalent.

The glass transition temperature (Tg) of the phenoxy resin is suitably 65°C to 160°C, preferably 70°C to 150°C. If the glass transition temperature is lower than 65° C., the moldability will be good, but problems will occur in the storage stability of the powder and the tackiness of the preform. If the temperature is higher than 160° C., the melt viscosity will be high and the moldability and the filling property into the fiber will be poor, and as a result, higher temperature press molding is required. The glass transition temperature of the phenoxy resin is a numerical value obtained from the peak value of the second scan, which is measured in the range of 20 to 280° C. under a temperature rising condition of 10° C./min using a differential scanning calorimeter.

The phenoxy resin is not particularly limited as long as it satisfies the above physical properties, but is a bisphenol A type phenoxy resin (for example, Phenotote YP-50, YP-50S, YP-55U manufactured by Nippon Steel Chemical & Material), bisphenol. F-type phenoxy resin (for example, Phenototo FX-316 manufactured by Nittetsu Chemical & Material), or copolymerization type phenoxy resin of bisphenol A and bisphenol F (for example, YP-70 manufactured by Nittetsu Chemical & Material), and other special Examples thereof include phenoxy resins (for example, Phenothote YPB-43C and FX293 manufactured by Nittetsu Chemical & Materials), and these can be used alone or in combination of two or more.

The resin composition of the present invention contains a maleic anhydride copolymer (B) as a crosslinking agent together with the phenoxy resin (A) for the purpose of improving the Tg of the matrix resin.
The acid anhydride group of the maleic anhydride copolymer (B) is hydrolyzed to form two carboxy groups from one acid anhydride group. Therefore, a functional group that reacts with the OH group of the phenoxy resin (A) is 2 It is understood that the phenoxy resin is three-dimensionally cross-linked by forming an ester bond with the secondary hydroxyl group of the phenoxy resin.
Therefore, the Tg of the crosslinked cured product of the resin composition can be greatly improved as compared with the phenoxy resin alone, and the formed three-dimensional crosslinks can be released by a hydrolysis reaction, so that the FRP molded products can be recycled. You can also give sex. That is, even when cross-linked and cured, since the ester bond between the phenoxy resin (A) and the maleic anhydride copolymer (B) is used for curing the matrix resin, it is possible to use a hydrolysis reaction. , FRP moldings can be separated into reinforcing fibers and matrix resin, and can be recycled without discarding.

The maleic anhydride copolymer (B) has two or more maleic anhydride-derived acid anhydrides that react with the secondary hydroxyl groups of the phenoxy resin, is solid at room temperature, and has no sublimation property. Although not particularly limited, maleic anhydride, polyolefin and styrene, a high molecular weight epoxy resin having a weight average molecular weight of about 5,000 to 10,000, and a phenoxy resin are used from the viewpoint of imparting heat resistance to a molded article, reactivity, and handleability. Copolymers with etc. are preferably used. In particular, a copolymer of maleic anhydride and styrene or polypropylene has less change in reactivity due to moisture absorption than an aromatic acid anhydride having two or more similar acid anhydrides capable of crosslinking and curing, and a phenoxy resin. It is the most preferable because it has good compatibility with epoxy resin.

The weight average molecular weight (Mw) of the maleic anhydride copolymer (B) is preferably 100,000 or less. When the weight average molecular weight exceeds 100,000, the fluidity at the time of melting is lowered, and therefore the crosslinking reaction occurs only in the vicinity of the maleic anhydride copolymer, and the crosslinking density is lowered, so that the physical properties of the FRP molded article are deteriorated. Not suitable for storage. On the other hand, although the lower limit of the weight average molecular weight is not particularly limited, a decrease in the weight average molecular weight may lead to a decrease in the moisture absorption resistance, and therefore it is at least 200 or more. Therefore, the weight average molecular weight of the maleic anhydride copolymer is preferably 200 to 100,000, more preferably 200 to 50,000, and further preferably 200 to 20,000.

The maleic anhydride copolymer (B) preferably has an acid value of 150 to 400. It is preferably 170 to 375, more preferably 200 to 300. Here, the acid value is represented by the number of mg of potassium hydroxide (KOH-mg/g) required to neutralize the acidic component contained in 1 g of the sample. If the acid value exceeds 400, the melt viscosity will be high and the crosslinking reaction will be difficult to occur. If it is less than 150, the number of crosslinking points will be small and the increase in Tg will be suppressed, which is not suitable for use. The softening point or Tg is preferably 160° C. or lower, more preferably 100 to 155° C. If the softening point or Tg exceeds 160° C., the crosslinking reaction with the phenoxy resin requires a long time, which requires pressing at high temperature for a long time, which is not preferable because the productivity of FRP is reduced.
The maleic anhydride copolymer (B) as a cross-linking agent may be used in combination with another cross-linking agent, for example, an aromatic acid dianhydride such as pyromellitic dianhydride (PMDA), as long as the effect of the present invention is not impaired. You may. However, it is less than 50% by weight of the crosslinking agent.

The amount of the maleic anhydride copolymer (B) to be blended is usually 0.1-1 mole of the acid anhydride group of the maleic anhydride copolymer (B) per 1 mol of the secondary hydroxyl group of the phenoxy resin (A). The amount is in the range of 0.6 mol, preferably in the range of 0.2 to 1.4 mol, and more preferably in the range of 0.6 to 1.2 mol. If the amount of the maleic anhydride copolymer (B) is too small, the crosslink density is low, resulting in poor mechanical properties and heat resistance. If it is too large, unreacted acid anhydride groups and carboxy groups adversely affect the properties of the crosslinked cured product. give.
Therefore, it is preferable that the epoxy resin (D) is blended as necessary and the blending amount of the epoxy resin (D) is adjusted according to the blending amount of the maleic anhydride copolymer (B). Specifically, the epoxy resin (D) is used for the purpose of reacting the carboxy group generated by the reaction between the secondary hydroxyl group of the phenoxy resin (A) and the maleic anhydride copolymer (B) with the epoxy resin (D). It is advisable that the compounding amount of) is within the range of 0.5 to 1.2 in terms of an equivalent ratio to the acid anhydride group of the maleic anhydride copolymer (B).

The resin composition of the present invention can be formed into a crosslinked resin by simply adding the maleic anhydride copolymer (B) to the phenoxy resin (A) or the resin composition containing the phenoxy resin (A) and the epoxy resin (D). Although the product can be obtained, it is essential to add the curing catalyst (C) so that the crosslinking reaction is surely performed and the Tg exhibits heat resistance of 160° C. or higher.

The curing catalyst is not particularly limited as long as it is a solid at room temperature and has no sublimation property. For example, a tertiary amine such as triethylenediamine, 2-methylimidazole, 2-phenylimidazole, 2-phenyl- Examples thereof include imidazoles such as 4-methylimidazole, organic phosphines such as triphenylphosphine, tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate, and aminopyridines such as 4-dimethylaminopyridine. These curing catalysts (accelerators) may be used alone or in combination of two or more.

The compounding amount of the curing catalyst (C) is 100 parts by weight of the total amount of the phenoxy resin (A) and the maleic anhydride copolymer (B), or the phenoxy resin (A) and the maleic anhydride copolymer (B), The total amount of the epoxy resin (D) is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight.

The epoxy resin (D) may be added to the resin composition of the present invention as described above. By blending the epoxy resin, it is possible to improve the impregnability into the reinforcing fiber base material by reducing the melt viscosity of the matrix resin and the heat resistance by improving the crosslink density of the matrix resin cured product.

The epoxy resin (D) is applicable to the present invention as long as it is a solid epoxy resin, for example, a bifunctional or higher epoxy resin is preferable, and a bisphenol A type epoxy resin (for example, Epototo YD manufactured by Nippon Steel Chemical & Material). -011, YD-7011, YD-900), bisphenol F type epoxy resin (for example, Epototo YDF-2001 manufactured by Nippon Steel Chemical & Material), diphenyl ether type epoxy resin (for example, YSLV-80DE manufactured by Nippon Steel Chemical & Material), Tetramethylbisphenol F type epoxy resin (for example, YSLV-80XY by Nippon Steel Chemical & Material), bisphenol sulfide type epoxy resin (for example, YSLV-120TE by Nippon Steel Chemical & Material), hydroquinone type epoxy resin (for example, Nittetsu Chemical & Material Epotote YDC-1312), phenol novolac type epoxy resin, (for example, Nippon Steel Chemical & Material Epototo YDPN-638), orthocresol novolac type epoxy resin (for example, Nippon Steel Chemical & Material Epototo YDCN-701, YDCN-702, YDCN-703, YDCN-704), aralkylnaphthalene diol novolac type epoxy resin (for example, ESN-355 manufactured by Nippon Steel Chemical & Material), triphenylmethane type epoxy resin (for example, EPPN manufactured by Nippon Kayaku Co., Ltd.) -502H) and the like, but not limited thereto, and two or more kinds thereof may be mixed and used.

The epoxy resin (D) is more preferably a crystalline epoxy resin that is solid at room temperature, has a melting point of 75° C. to 145° C., and a viscosity at 160° C. of 1.0 Pa·s or less. The crystalline epoxy resin has a low melt viscosity, is easy to handle, and can reduce the melt viscosity of a matrix resin containing a phenoxy resin as an essential component. When the melt viscosity exceeds 1.0 Pa·s, the filling property of the matrix resin into the reinforced fiber base material is poor, and the obtained fiber reinforced plastic molded product (FRP molded product) is poor in homogeneity.

When the epoxy resin (D) is present, the reaction of the phenoxy resin (A), the maleic anhydride copolymer (B) and the epoxy resin (D) is carried out by reacting the secondary hydroxyl group in the phenoxy resin (A) with maleic anhydride. The copolymer (B) is crosslinked and cured by an esterification reaction with an acid anhydride group, and further by a reaction between the epoxy group of the epoxy resin (D) and a benzyl group produced by this esterification reaction. A phenoxy resin cross-linked product can be obtained by the reaction of the phenoxy resin (A) and the maleic anhydride copolymer (B). However, the coexistence of the epoxy resin (D) results in the secondary hydroxyl group of the phenoxy resin and the maleic anhydride copolymer. The carboxy group formed by the reaction with the acid anhydride group of the polymer (B) is bonded to the epoxy group of the epoxy resin to accelerate the cross-linking reaction and increase the cross-linking density, and reduce the melt viscosity of the matrix resin. Thus, the impregnating property into the reinforcing fiber base material can be enhanced. As a result, it becomes a suitable FRP molding material for obtaining an excellent FRP molded product such as improved mechanical strength.
In the present invention, even when the epoxy resin (D) coexists, the main component is the phenoxy resin (A) which is a thermoplastic resin, and the secondary hydroxyl group and the maleic anhydride copolymer ( It is considered that the esterification reaction of B) with the acid anhydride group has priority. That is, when the maleic anhydride copolymer (B) and the epoxy resin (D) and the phenoxy resin (A) coexist, the reaction between the acid anhydride of the maleic anhydride copolymer and the secondary hydroxyl group of the phenoxy resin is first performed. Then, the unreacted maleic anhydride copolymer (B) is ring-opened to react with the carboxy group and the epoxy resin (D) to further improve the crosslinking density. Therefore, the FRP molding material of the present invention has good moldability, unlike ordinary prepregs containing an epoxy resin as a main component, which is a thermosetting resin, and has long-term room temperature in a state where humidity control is not performed. Even after storage, the moldability and physical properties of FRP molded products are maintained, and storage stability is excellent.

The resin composition of the present invention contains a phenoxy resin as a resin component in an amount of more than 30 wt%, preferably 45 wt% or more. Here, the resin component includes an epoxy resin in addition to the phenoxy resin and the maleic anhydride copolymer, but does not include a non-resin component such as a curing catalyst. Further, the matrix resin includes a crosslinking agent and a curing catalyst in addition to the resin component, but does not include the reinforcing fiber base material.

When the epoxy resin (D) is used in combination with the phenoxy resin (A), the blending amount of the phenoxy resin (A) and the epoxy resin (D) is the epoxy resin (D) based on 100 parts by weight of the phenoxy resin (A). It is advisable to add them in an amount of 1 to 35 parts by weight. The blending amount of the epoxy resin (D) is preferably 3 to 30 parts by weight, more preferably 5 to 25 parts by weight. When the blending amount of the epoxy resin (D) exceeds 35 parts by weight, it takes time to cure the epoxy resin, so that it becomes difficult to obtain the strength required for demolding in a short time, and the recyclability of FRP is deteriorated. Further, when the amount of the epoxy resin (D) is less than 1 part by weight, the effect of improving the crosslink density due to the mixture of the epoxy resin cannot be obtained, and the cured product of the matrix resin hardly develops Tg of 160° C. or higher. Since the fluidity of the matrix resin deteriorates, it may be difficult to impregnate the reinforcing fiber base material.

The resin composition of the present invention is solid at room temperature even when it contains an epoxy resin together with a phenoxy resin and a maleic anhydride copolymer, and its melt viscosity is 3000 Pa in any temperature range of 160 to 280°C.・It must be s or less. The melt viscosity is preferably 2500 Pa·s or less and 30 Pa·s or more, and more preferably 2200 Pa·s or less and 30 Pa·s or more. If the melt viscosity exceeds 3000 Pa·s, the reinforcing fiber base material will not be sufficiently impregnated with the matrix resin during molding by hot pressing, and defects such as internal voids will occur and the physical properties of the matrix resin of the molded product will also vary. , The mechanical properties of the FRP molded product deteriorate. Further, if the melt viscosity is too low, the flowability of the resin composition becomes too large, which makes it difficult to control the fiber volume content of the FRP molded product, which may deviate from the desired value. Is preferred.

The melt viscosity of the resin composition of the present invention decreases as the temperature rises, and then the melt viscosity rapidly increases due to the initiation of the crosslinking reaction. Therefore, normally, in the temperature range of 160 to 280° C. which is the molding temperature, the minimum melt viscosity before the start of the crosslinking reaction may be 3000 Pa·s or less. As described above, when the melt viscosity of the matrix resin is 3000 Pa·s or less in any of the 160 to 280°C temperature range, a desired FRP molded product can be obtained. However, even if the melt viscosity of the phenoxy resin alone is 3000 Pa·s or less in any of the temperature ranges of 160 to 280° C., the crosslinking reaction is initiated early by the maleic anhydride copolymer, and the melt as the matrix resin is melted. The viscosity may exceed 3000 Pa·s in any of the above temperature ranges. Therefore, the melt viscosity of the matrix resin, not the melt viscosity of the phenoxy resin, must be 3000 Pa·s or less in any of the above temperature ranges.
Depending on the type of phenoxy resin, the temperature at which the melt viscosity becomes 3000 Pa·s or less fluctuates somewhat, but if the melt viscosity is 3000 Pa·s or less at least in the temperature range of 160 to 280° C., which is the molding temperature, FRP molding is possible. Although the molding temperature can be higher, for example, 300° C., it is likely to exceed 3000 Pa·s due to the accelerated crosslinking reaction.

A flame retardant and a flame retardant aid may be blended in the resin composition of the present invention. Any flame retardant may be used as long as it is a solid at room temperature and has no sublimation property. For example, an inorganic flame retardant such as calcium hydroxide or an organic or inorganic phosphorus flame retardant such as ammonium phosphates or phosphate ester compounds. Examples thereof include a flame retardant, a nitrogen-containing flame retardant such as a triazine compound, and a brominated flame retardant such as a brominated phenoxy resin. Among them, a brominated phenoxy resin and a phosphorus-containing phenoxy resin can be preferably used because they can be used as a flame retardant/matrix resin.
The blending amount of the flame retardant (and the flame retardant aid) is appropriately selected depending on the kind of the flame retardant and the desired degree of flame retardancy, but is generally 0.01 to 50 parts by weight with respect to 100 parts by weight of the matrix resin. Within the range, it is preferable to mix them in such an amount that the adhesion of the matrix resin and the physical properties of the FRP molded product are not impaired.

Furthermore, in the resin composition of the present invention, a thermoplastic resin powder other than a phenoxy resin, for example, in a range that does not impair the good adhesion of the matrix resin powder to the fiber base material and the physical properties of the FRP molded product after molding, for example, Powders of polyvinylidene chloride resin, natural rubber, synthetic rubber, etc., and various additives such as various inorganic fillers, extender pigments, colorants, antioxidants, UV inhibitors and the like can also be added.

The resin composition of the present invention serves as the matrix resin of the FRP molding material, and is adhered or impregnated on the reinforcing fiber base material by a known method, but it is preferable to use a method that does not use a solvent. As such a method, a method of melt-impregnating a resin composition formed into a film on a reinforcing fiber substrate (press-fitting method, film stack method) or a method of mixing continuous fibers spun with the resin composition with a reinforcing fiber (commingle method) ), and a method (powder coating method, powder coating method) of spraying/coating the powdered resin composition on the reinforcing fiber base material. Among them, the powder coating method is for FRP molding, in which the reinforcing fibers are less likely to break when manufacturing the FRP molding material, have flexibility, and have breathability, so that internal bubbles are less likely to be generated even when laminated in a high multilayer. This is a more preferable method because a material can be obtained.

The adhesion amount (resin ratio: RC) of the matrix resin in the FRP molding material (prepreg) using the resin composition of the present invention is 20 to 50% by weight, preferably 25 to 45%, and more preferably 25-40%. When RC exceeds 50%, mechanical properties such as tensile and flexural modulus of FRP are deteriorated, and when it is less than 20%, the resin adhesion amount is extremely small. There is a concern that it will be sufficient and that both thermophysical properties and mechanical properties will deteriorate.

In the FRP molding material using the resin composition of the present invention, at least a part of the reinforcing fiber base material is covered with the resin composition. Alternatively, at least a part of the reinforcing fiber base material is impregnated with the resin composition.

The fiber constituting the reinforcing fiber base material is at least one fiber selected from the group consisting of carbon fiber, boron fiber, silicon carbide fiber, glass fiber and aramid fiber, and includes two or more fibers. It may be one. The fiber is preferably a carbon fiber having high strength and good thermal conductivity, and in particular, the pitch-based carbon fiber is not only high in strength but also high in thermal conductivity, so that the generated heat can be quickly diffused. More preferable.

The form of the reinforcing fiber substrate is not particularly limited, and for example, a unidirectional material, a cloth such as plain weave or twill, a three-dimensional cloth, a chopped strand mat, a tow consisting of several thousand or more filaments, or a non-woven fabric is used. Can be used. These reinforcing fiber bases may be used alone or in combination of two or more. In the FRP molding material of the present invention, at least a part of the reinforcing fiber base material is covered or impregnated with the thermoplastic resin composition. When the coating or impregnation of the reinforcing fiber base material is performed by the powder coating method, it is preferable to use the opened reinforcing fiber base material. The fiber opening process makes it easier to impregnate the inside of the reinforced fiber base material with the matrix resin when forming the molding material by powder coating or the film stack method, and during the subsequent molding process. Higher physical properties can be expected.

The reinforcing fibers are preferably those having a sizing material (a sizing agent) or a coupling agent attached to the surface thereof, because the wettability of the matrix resin with the reinforcing fibers and the handleability can be improved. Examples of the sizing agent include maleic anhydride-based compounds, urethane-based compounds, acryl-based compounds, epoxy-based compounds, phenol-based compounds or derivatives of these compounds, among which sizing agents containing epoxy-based compounds are preferred. It can be used. Examples of the coupling agent include amino-based, epoxy-based, chloro-based, mercapto-based, and cationic-based silane coupling agents, and amino-based silane-based coupling agents can be preferably used. The content of the sizing material and the coupling agent is 0.1 to 10 parts by weight, and more preferably 0.5 to 6 parts by weight, based on 100 parts by weight of the reinforcing fiber. With this content, the wettability with the matrix resin and the handleability are excellent.

The FRP molded product can be easily produced by heating the single FRP molding material using the resin composition of the present invention or by laminating a plurality of materials and heating and pressing. That is, it becomes possible to simultaneously perform shaping and complete impregnation of the matrix resin into the reinforcing fiber base material by pressure molding by hot pressing. Molding using the FRP molding material can be carried out by various molding methods such as autoclave molding and hot press molding using a metal mold, depending on the size and shape of the desired FRP molded product, as long as it is heat and pressure molding. It can be selected and implemented.

The molding temperature in the heat and pressure molding is, for example, 160 to 280°C, preferably 180°C to 270°C, more preferably 180°C to 260°C. If the molding temperature exceeds the upper limit temperature, excessive heat will be applied more than necessary, and there is a risk of excessive resin outflow and thermal deterioration.Moreover, the time required for heating and cooling will increase the molding time (tact time). The productivity will deteriorate. On the other hand, when the temperature is lower than the lower limit temperature, the melt viscosity of the matrix resin is high, so that the impregnability of the matrix resin into the reinforcing fiber base material is deteriorated. The molding time is usually 10 to 60 minutes.

The demolding temperature of the manufactured FRP molded product is set in consideration of the type and composition of the matrix resin, the productivity, etc., but is 100 to 120° C., for example. The resin composition of the present invention has a much higher heat resistance than that before molding due to the crosslinking reaction utilizing the secondary hydroxyl group of the phenoxy resin, and thus the demolding temperature can be increased.
Further, since the crosslinking reaction between the phenoxy resin and the maleic anhydride copolymer proceeds according to the length of thermal history, for example, instead of shortening the pressing time, a heat treatment performed in a later step is used to reheat The crosslinking reaction can also be completed by adding history.

Hereinafter, the present invention will be described more specifically by showing Examples and Comparative Examples, but the present invention is not limited to the description of these Examples. The tests and measuring methods for various physical properties are as follows.

Average particle size (d50)
The average particle size of fine powders such as matrix resin is measured by a laser diffraction-scattering particle size distribution measuring device (Microtrac MT3300EX, manufactured by Nikkiso Co., Ltd.) when the cumulative volume is 50% on a volume basis. did.

Melt Viscosity Using a rheometer (manufactured by Anton Paar), a 5 mm ³ sample was sandwiched between parallel plates, and the temperature was raised at 5° C./min while the frequency was 1 Hz and the load strain was 0.5%. The melt viscosity at ˜270° C. was measured.
In addition, Table 1 shows the minimum value of the melt viscosity in the measurement temperature range.

Moisture absorption resistance of resin composition 0.5 g of resin composition powder was placed in an aluminum cup and left in a constant temperature and humidity tester adjusted to 35° C. and 80% RH, and left for 1 hr, 2 hr, 5 hr, 24 hr, 48 hr, 72 hr, After 168 hours, it was taken out each time and the change in its properties was confirmed.
If the powder is lumped due to moisture absorption, or if the properties have changed significantly, the moisture absorption resistance is poor, and it is indicated as ×.If the powder properties are not particularly changed, it is indicated as good moisture absorption resistance. ..

Glass transition temperature (Tg) of resin composition
The resin composition powder was compression-molded to prepare a test piece having a size of 6 mmΦ×2 mmt, and using a dynamic viscoelasticity measuring device (DMA 7e manufactured by Perkin Elmer), a temperature rising condition of 5° C./min, 25 to 250. The maximum peak of tan δ obtained by measuring in the range of °C was taken as the glass transition point.

Heat Resistance of Resin Composition The glass transition temperature of the resin composition was evaluated by the amount of movement of the probe before and after the measurement when measured with a dynamic viscoelasticity measuring device. When the amount of movement of the probe was less than 0.5 mm, it was marked with ⊚, when less than 1 mm was marked with ◯, and when 1 mm or more was marked with x.

Glass transition temperature (Tg) of FRP molded product
Using a diamond cutter, a test piece having a width of 10 mm and a length of 10 mm was prepared from a laminated plate having a thickness of 2 mm prepared by laminating FRP molding materials and hot pressing, and using the above-mentioned dynamic viscoelasticity measuring device. Was measured at a temperature rising condition of 5° C./min under the range of 25 to 250° C., and the maximum peak of tan δ obtained was taken as the glass transition point.

Resin ratio (RC:%)
It was calculated from the weight (W1) of the reinforcing fiber cloth before the matrix resin was attached and the weight (W2) of the FRP molding material after the resin was attached, using the following formula.
Resin ratio (RC:%)=(W2-W1)/W2×100
W1: Weight of reinforcing fiber cloth before resin adhesion W2: Weight of FRP molding material after resin adhesion

Fiber volume content (Vf:%)
The fiber volume content of FRP was measured by the combustion method based on the JIS K 7075:1991 carbon fiber reinforced plastic fiber content and void content test method.

Mechanical Strength JIS K 7074:1988 The mechanical properties of the obtained FRP laminated plate were measured based on the bending test method of carbon fiber reinforced plastic.

Storage stability (P/P storage stability)
After leaving the FRP molding material for 24 hours in a thermo-hygrostat set to a temperature of 35° C. and a humidity of 80% RH, 10 sheets were stacked on a fluororesin sheet and pressed with a press machine heated to 200° C. for 5 MPa for 5 minutes. A laminated board was prepared and evaluated for thermophysical properties and mechanical properties. A comparison was made with a laminated plate using the FRP molding material before standing, and if the difference in physical properties was within ±10%, it was regarded as acceptable, and was marked as ◯ in the table.

Presence or absence of post cure The FRP molding material molded at 5 MPa, 260° C. for 10 minutes with a heat press was heat-treated in an oven at 240° C. for 1 hour, and Tg before and after the heat treatment was measured. If the Tg before the treatment was 160° C. or higher and the difference between the Tg before and after the treatment was within 10° C., post cure was not required.

The materials used in the examples and comparative examples are as follows.

Phenoxy resin (A)
(A-1) Phenothote YP-50S (bisphenol A type manufactured by Nittetsu Chemical & Materials, Mw=60,000, hydroxyl equivalent=284), Tg=84° C., melt viscosity at 200° C.=400 Pa·s

Maleic anhydride copolymer (B)
(B-1): SMA resin EF-30 (manufactured by Kawara Yuka, Mw: 9500, acid value: 282, Tg: 125° C.)
(B-2): SMA resin EF-40 (manufactured by Kawara Yuka Co., Ltd., Mw: 11000, acid value: 210, Tg: 115° C.)
(B-3): SMA resin EF-80 (manufactured by Kawahara Yuka Co., Ltd., Mw: 14000, acid value: 120, Tg: 104° C.)
(B-4): XIBOND160 (manufactured by POLY SCOPE, acid value: 250, Mw: 115000, Tg: 150° C.)

Epoxy resin (D)
(D-1): YSLV-80XY (Tetramethylbisphenol F type, manufactured by Nittetsu Chemical & Materials, epoxy equivalent: 192, melting point: 72°C)

Curing catalyst (C)
(C-1): 4-dimethylaminopyridine (DMAP, manufactured by Koei Chemical Industry Co., Ltd.)
(C-2): 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (Cureazole 2MZ-A, manufactured by Shikoku Kasei)

Aromatic acid dianhydride (E-1): ethylene glycol bisanhydrotrimellitate (manufactured by Shin Nippon Rika, acid anhydride equivalent: 207, melting point: 160°C, TEMG)

Example 1
The phenoxy resin (A-1), the maleic anhydride copolymer (B-1), and the curing catalyst (C-1) were crushed and classified, respectively, and the average particle diameter d50 was 80 μm (the average particle diameter of A, B, and C). The phenoxy resin (A-1) has a secondary hydroxyl group and the maleic anhydride copolymer (B-1) has an acid anhydride group molar ratio of 1:1. In this manner, dry blending was carried out in the proportions (parts by weight) shown in Table 1 to prepare a matrix resin composition powder. Then, a plain weave reinforcing fiber base material made of carbon fiber (STANDARD Modulus type HTS40 3K, manufactured by Toho Tenax Co., Ltd.) was subjected to powder coating under an electrostatic field under conditions of an electric charge of 100 kV and a blowing air pressure of 0.32 MPa. went. Thereafter, the resin was heat-melted in an oven at 180° C. for 1 minute to heat-bond the resin to obtain an FRP molding material. The resin ratio (RC) of the obtained FRP molding material was 33%.
Various physical properties were measured for a 1 mm-thick FRP cured product obtained by stacking the above FRP molding materials and press-molding them with a hot press machine under the conditions of 5 MPa, 260° C. and 10 min. The results are shown in Table 1.

Example 2
Same as Example 1 except that the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-1) was set to 1:0.2. Then, various physical properties of the matrix resin composition, the FRP molding material (RC: 31%), and the FRP cured product were measured. The results are shown in Table 1.

Example 3
Same as Example 1 except that the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-1) was set to 1:1.4. Then, various physical properties of the matrix resin composition, the FRP molding material (RC: 30%), and the FRP cured product were measured. The results are shown in Table 1.

Example 4
In addition to the phenoxy resin (A-1), the maleic anhydride copolymer (B-1) and the curing catalyst (C-1), the epoxy resin (D-1) was crushed and classified, and the average particle diameter d50 was 80 μm. (A-1, B-1, C-1, and D-1 have almost the same average particle size) Powder was dry-blended at the ratio (parts by weight) shown in Table 1 to obtain a matrix resin composition. Various physical properties of the matrix resin composition, the FRP molding material (RC: 32%), and the FRP cured product were measured in the same manner as in Example 1 except that the material powder was produced. The results are shown in Table 1.

Example 5
Various physical properties of the matrix resin composition, FRP molding material (RC: 33%), and FRP cured product were measured in the same manner as in Example 1 except that the amount of the curing catalyst (C-1) blended was 3 parts by weight. did. The results are shown in Table 1.

Example 6
A matrix resin composition and a FRP molding material (RC: 33%) were prepared in the same manner as in Example 1 except that the curing catalyst (C-1) was changed to (C-2) and the compounding amount was 3 parts by weight. Various physical properties of the FRP cured product were measured. The results are shown in Table 1.

Example 7
In addition to the phenoxy resin (A-1), the maleic anhydride copolymer (B-2) and the curing catalyst (C-1), the epoxy resin (D-1) was crushed and classified to obtain an average particle diameter d50 of 80 μm. (A, B, and C have approximately the same average particle size) The powdered powder is used as an acid anhydride of the secondary hydroxyl group of the phenoxy resin (A-1) and the maleic anhydride copolymer (B-2). FRP molding material (RC: 33%), FRP were prepared in the same manner as in Example 1 except that the matrix resin composition powder was prepared by mixing and dry blending so that the molar ratio of the groups was 1:0.2. Various physical properties of the cured product were measured. The results are shown in Table 1.

Comparative Example 1
The phenoxy resin (A-1), the epoxy resin (D-1), and the aromatic dianhydride (E-1) were crushed and classified, respectively, and the average particle diameter d50 was 80 μm (the average particle diameter of A, D, and E). Powders of the phenoxy resin (A-1) and the acid anhydride group of the aromatic dianhydride (E-1) in a molar ratio of 1:1 and epoxy. The epoxy groups of the resin (D-1) and the aromatic dianhydride (E-1) were dry-blended at a ratio (parts by weight) shown in Table 2 such that the molar ratio was 1:0.6. A matrix resin composition powder was produced. Then, a plain weave reinforcing fiber base material made of carbon fiber (STANDARD Modulus type HTS40 3K, manufactured by Toho Tenax Co., Ltd.) was subjected to powder coating under an electrostatic field under conditions of an electric charge of 100 kV and a blowing air pressure of 0.32 MPa. went. Thereafter, the resin was heat-melted in an oven at 180° C. for 1 minute to heat-bond the resin to obtain an FRP molding material. The resin ratio (RC) of the obtained FRP molding material was 30%.
Various physical properties were measured for a 1 mm-thick FRP cured product obtained by stacking the above FRP molding materials and press-molding them with a hot press machine under the conditions of 5 MPa, 260° C. and 10 min. The results are shown in Table 2.

Comparative example 2
Same as Example 1 except that the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-1) was set to 1:0.05. Then, various physical properties of the matrix resin composition, the FRP molding material (RC: 29%), and the FRP cured product were measured. The results are shown in Table 2.

Comparative Example 3
Example 1 was repeated except that the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-1) was set to 1:9. Various physical properties of the matrix resin composition, FRP molding material (RC: 29%), and FRP cured product were measured. The results are shown in Table 2.

Comparative Example 4
(B-3) was used as the maleic anhydride copolymer, and the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-3) was 1:0. Various physical properties of the FRP molding material (RC: 33%) and the FRP cured product were measured in the same manner as in Example 1 except that the components were blended so as to be 0.2 and dry-blended. The results are shown in Table 2.

Comparative Example 5
Using (B-4) as the maleic anhydride copolymer, the molar ratio of the secondary hydroxyl group of the phenoxy resin (A-1) to the acid anhydride group of the maleic anhydride copolymer (B-4) is 1:1. Various physical properties of the FRP molding material (RC: 30%) and the FRP cured product were measured in the same manner as in Example 1 except that the components were blended so as to be dry-blended. The results are shown in Table 2.

From Tables 1 and 2, Examples 1 to 7 of the present invention can provide CFRPs having higher Tg and heat resistance than Comparative Examples 2 to 4 and better mechanical properties than Comparative Example 5. In addition, in Comparative Example 1 which has almost the same Tg and heat resistance as the resin composition using the aromatic dianhydride cross-linking agent of Comparative Example 1, excellent moisture resistance and does not require post cure. It turns out that it has an excellent effect that was not achieved.

The fiber-reinforced plastic molding material of the present invention is used as a fiber-reinforced plastic (FRP) material for housing electronic devices such as notebook PCs and tablets, arms for industrial robots, reinforcing materials for building structures, and sports leisure. It can be used in a wide range of fields including fields.

Claims

A resin composition used together with a reinforced fiber substrate as a material for molding a fiber reinforced plastic, comprising a phenoxy resin (A), a maleic anhydride copolymer (B) as a crosslinking agent, and a curing catalyst (C). As an essential component, the maleic anhydride copolymer (B) has a weight average molecular weight of 100,000 or less, an acid value of 150 to 400 KOH-mg/g, and a secondary hydroxyl group of the phenoxy resin (A), A resin composition, wherein the acid anhydride group of the maleic anhydride copolymer (B) is mixed in a molar ratio of 1/0.1 to 1/1.6.
The resin composition according to claim 1, wherein the maleic anhydride copolymer (B) is a copolymer with styrene.
The resin composition according to claim 1, wherein the resin composition further comprises an epoxy resin (D).
The resin composition according to any one of claims 1 to 3, wherein the crosslinked or cured resin composition has a glass transition temperature (Tg) of 160°C or higher.
A fiber-reinforced plastic molding material in which at least a part of a reinforcing fiber base material is coated or impregnated with the resin composition according to any one of claims 1 to 4.
The fiber constituting the reinforcing fiber base material contains one or more fibers selected from the group consisting of carbon fiber, boron fiber, silicon carbide fiber, glass fiber and aramid fiber. Fiber reinforced plastic molding material.
A fiber-reinforced plastic molded product obtained by molding the fiber-reinforced plastic molding material according to claim 5 or 6.