WO2022158559A1

WO2022158559A1 - Fiber-reinforced plastic molding material and molded object thereof

Info

Publication number: WO2022158559A1
Application number: PCT/JP2022/002152
Authority: WO
Inventors: 浩之 ▲高▼橋; 涼丞原子
Original assignee: 日鉄ケミカル＆マテリアル株式会社
Priority date: 2021-01-22
Filing date: 2022-01-21
Publication date: 2022-07-28
Also published as: TW202237711A

Abstract

A fiber-reinforced plastic molding material giving molded articles which, even when used at around the processing temperature, are inhibited from suffering spring back is provided without requiring the use of any super-engineering plastic, which is difficult to process.　A thermoplastic resin composition according to the present invention includes one or more thermoplastic resins which, after having been infiltrated into a reinforcing fibrous base, become the matrix resin of a fiber-reinforced plastic, and is characterized in that the thermoplastic resins comprise a phenoxy resin as an essential component and account for 50 wt% or more of the whole resin composition and that when the resin composition is heated from room temperature to 280°C and then cooled to room temperature again with a rheometer, the resin composition has melt viscosities exceeding 10,000 Pa·s at the temperatures not higher than 220°C.

Description

Fiber-reinforced plastic molding material and its molding

TECHNICAL FIELD The present invention relates to a fiber-reinforced plastic molding material and a molded article thereof, which can provide a fiber-reinforced plastic molded article having excellent heat resistance and suppressing springback even when placed in a high-temperature environment. It is.

Fiber-reinforced thermoplastic (FRTP), which uses thermoplastic resin as the matrix resin, enables higher productivity and recycling of used materials than fiber-reinforced plastic (FRP), which uses thermosetting resin such as epoxy resin as the matrix resin. Therefore, technical development is underway for practical use.

However, in CFRTP, especially when a nonwoven fabric made from carbon fiber short fibers is used as a reinforcing fiber base material, the matrix resin softens during the preheating process during molding by hot press and during demolding after molding. In this state, the reinforcing fiber base material expands due to the restoring force, which causes problems such as decomposition of the resin, deterioration of the surface properties of the molded article, and generation of voids in the molded article. In addition, in actual use, when the ambient temperature is close to the molding processing temperature, the restoring force of the reinforcing fiber base material cannot be suppressed, and the molded body undergoes a dimensional change more than expected.

The restoring force of the reinforcing fiber base material mentioned above is also called springback, and in order to reduce it, a super engineering plastic with a very high glass transition temperature (Tg) and melting point is used as the matrix resin, and the blending ratio with the reinforcing fiber is adjusted. A method of adjusting (Patent Document 1), a method of using a thermoplastic resin that has a storage elastic modulus of a certain value or more by dynamic viscoelasticity measurement at 200 ° C. as a matrix resin (Patent Document 2), a heat treatment that becomes a matrix resin A method of adding carbon black or the like to a plastic resin to improve the strength of the resin has been studied (Patent Document 3).

JP 2016-190955 JP 2014-95034 WO2015/016252

However, the use of super engineering plastics with extremely high Tg and melting points requires processing at extremely high temperatures (about 300°C), which entails technical difficulties in the production of FRTP. In addition, in the method of increasing the elastic modulus of the resin at high temperatures, the elastic modulus decreases in an environment exceeding the Tg or melting point of the thermoplastic resin used as the matrix resin, so the effect of suppressing springback becomes insufficient. There is

Therefore, in the present invention, without using super engineering plastics that are difficult to process, FRTP in which springback is suppressed even when the molded product is used near the processing temperature is used by a method different from that of the prior documents 1 to 3. An object of the present invention is to provide a resin composition that can be obtained.

The present inventors have found that a fiber-reinforced plastic molding material in which a reinforcing fiber base material is impregnated with a resin composition containing a thermoplastic resin has a resin composition that serves as a matrix resin of the fiber-reinforced plastic when formed into a molded product. The inventors have found that by using a matrix resin composition having a melt viscosity of 10,000 Pa·s or more in a temperature range of 220°C or less, a molded article has both excellent heat resistance and dimensional stability, and have arrived at the present invention. is.

The present invention is a resin composition containing a thermoplastic resin that becomes a matrix resin of a fiber-reinforced plastic after being impregnated into a reinforcing fiber base material,
50 wt% or more of the entire resin composition is a thermoplastic resin containing a phenoxy resin as an essential component,
A thermoplastic resin composition characterized by having a melt viscosity exceeding 10000 Pa s in a temperature range of 220° C. or lower when the temperature is raised from room temperature to 280° C. using a rheometer and then cooled to room temperature again. be.

30 wt% to 70 wt% or less of the matrix resin is the phenoxy resin (A), and the remainder is a second thermoplastic resin (B- 1 to 3) are preferred.
Moreover, it is also suitable to contain an epoxy resin (C) together with a thermoplastic resin as a matrix resin.
It is preferable that the resin composition serving as the matrix resin exhibit mutual reactivity or crosslinkability.

The present invention provides a fiber-reinforced plastic molding material obtained by impregnating a reinforcing fiber base material with the above resin composition, and a molded article obtained by molding the fiber-reinforced plastic molding material.
It is preferable that the molded article of the present invention has a change rate of more than 0% and less than 10% in the thickness of the fiber-reinforced plastic after standing for 10 minutes in the same thermal environment as the temperature during molding and then cooling to room temperature. be.

In the fiber-reinforced plastic using the resin composition of the present invention as the matrix resin, the softening of the matrix resin is very small and the springback of the reinforcing fiber is suppressed even after being molded and placed in an environment above the molding temperature. , High retention rate of mechanical strength in high temperature environment, and deformation of molded products is less likely to occur. Therefore, it is particularly useful as a FRTP material, particularly a CFRTP material, for structural members used in harsh environments such as automobiles and aerospace.
Moreover, since the matrix resin is composed of a general-purpose resin material that is not a super engineering plastic, the material and manufacturing costs are low.

The present invention will be described in detail below.

The matrix resin composition used in the fiber-reinforced plastic molding material of the present invention contains a thermoplastic resin. The matrix resin is also called MT resin.
Examples of thermoplastic resins include polyolefins such as phenoxy resins (also known as thermoplastic epoxy resins), polyamide resins, polyester resins, polycarbonate resins, and acid anhydride-modified polypropylene resins. In particular, a phenoxy resin that has good affinity and impregnation with the reinforcing fiber base material, has a residual epoxy group at the molecular chain end, and is easy to use the secondary hydroxyl group of the side chain for the cross-linking reaction is preferably used. .
As the matrix resin, a thermosetting resin such as an epoxy resin can be used together with a thermoplastic resin. %, more preferably 75-100 wt%. If the thermoplastic resin in the matrix resin is less than 50% by weight, the effect of the thermosetting resin becomes more pronounced. decreases.

In the fiber-reinforced plastic molding material of the present invention, the melt viscosity of the matrix resin (resin composition) measured when the temperature is raised from room temperature to 280°C using a rheometer and then cooled to room temperature again is 220°C or less. It exceeds 10000 Pa·s in the temperature range of . The melt viscosity of the matrix resin is preferably 12000 Pa·s or more, more preferably 15000 Pa·s or more. If the melt viscosity of the matrix resin is 10,000 or less, the matrix resin softens more than necessary when the molded article is exposed to a high-temperature environment, and flows against the repulsive force of the reinforcing fiber base material. A springback phenomenon occurs.
In the present invention, the temperature at which the melt viscosity exceeds 10000 Pa s is defined as a temperature range of 220 ° C. or less, which allows the molded CFRP to have a margin in heat resistance even if it is exposed to an environment of about 200 ° C. It's for. Of course, if the melt viscosity exceeds 10000 Pa·s even at 220°C or higher, the effect of the present invention can be obtained, but the upper limit is about 280°C.
In addition, in the measurement of melt viscosity, the melt viscosity (ρ ₂₂₀₊ ) when reaching 220 ° C. when the temperature was raised from room temperature to 280 ° C., and the minimum value of melt viscosity (ρ ₂₂₀ ≧), it is desirable that the melt viscosity (ρ _220≧ ) is greater than the melt viscosity (ρ ₂₂₀₊ ). Furthermore, the matrix resin of the present invention melts at a glass transition point of +100° C. or -5° C. from the melting point of the main resin component alone constituting the matrix resin (the resin component alone having low thermophysical properties when the constituent components are in equal amounts). More preferably, the viscosity (ρ _Tg+100 , ρ _Tm−5 ) is higher than the melt viscosity of the main resin alone constituting the matrix resin.
As described above, the magnitude of the melt viscosity parameter of the matrix resin composition when the temperature is raised and lowered satisfies the above relationship, so that the fiber-reinforced plastic molded article obtained from the fiber-reinforced plastic molding material of the present invention can be heated at a temperature as high as 200°C. Even when placed in an environment, even if the matrix resin softens, its fluidity is greatly suppressed, so the springback phenomenon does not easily occur, and the dimensional accuracy and mechanical properties of fiber-reinforced plastic molded products can be maintained.

On the other hand, the matrix resin composition used in the fiber-reinforced plastic molding material of the present invention has a minimum melt viscosity of 3000 Pa·s or less when heated from room temperature to 280°C. It is suitable for good impregnation of the matrix resin into the fiber base material. The minimum melt viscosity is preferably 50 to 3000 Pa·s, more preferably 100 to 2500 Pa·s.

The matrix resin includes a thermoplastic resin and is not particularly limited as long as it exhibits the predetermined melt viscosity behavior described above, but may be a mixture of two or more resins having reactivity with each other. More preferably, it is a mixture of two or more resins having crosslinkability.
The presence or absence of reactivity of the matrix resin composition is determined by the presence or absence of an increase in melt viscosity when the resin composition is heated to 280°C with a rheometer and then held at 280°C for 30 minutes or more. can judge.
It is preferable to exhibit a reactivity that can confirm an increase in melt viscosity (Δρ) by a factor of 2 or more during the holding period at 280°C. More preferably, the reactivity is such that a melt viscosity increase of 5 times or more can be confirmed.

A mixture of two or more resins having reactivity with each other is a resin composition in which residual reactive groups at polymer chain ends have reacted, and examples thereof include a combination of a phenoxy resin and a polyamide resin.
Both the phenoxy resin (A) and the polyamide resin (B) are resins having a polar group, and the phenoxy resin (A) has a residual epoxy group at the polymer chain end, and the polyamide resin (B-1) has a residual amine group. Alternatively, it has a carboxyl group, and when the two are blended, the compatibility is good, so it is presumed that the two react to some extent.

The blending ratio of the phenoxy resin (A) and the second thermoplastic resin (B) selected from any one of the group consisting of polyamide resin, polycarbonate resin and aromatic polyester resin is 100 mass in total for both. %, the ratio of the phenoxy resin (A) should be 30 to 70% by mass, and the ratio of the second thermoplastic resin (B) should be 30 to 70% by mass. That is, it is preferable to mix them in a ratio of 30/70 to 70/30 in a mixing ratio (mass ratio) represented by (A)/(B). The compounding ratio (A)/(B) is preferably 70/30 to 40/60, more preferably 70/30 to 50/50. When the compounding ratio (A)/(B) exceeds 70/30 and the ratio of the phenoxy resin (A) is further increased, the effect of improving the heat resistance by compounding the second thermoplastic resin is no longer observed. In addition, when the compounding ratio (A)/(B) is less than 30/70 and the ratio of the second thermoplastic resin (B) is increased, the rigidity improvement due to the compounding of the phenoxy resin is not observed, so it is Rigidity at

A phenoxy resin is a thermoplastic resin obtained from a condensation reaction between a dihydric phenol compound and epihalohydrin or a polyaddition reaction between a dihydric phenol compound and a bifunctional epoxy resin. method can be obtained. Resins called polyhydroxypolyether resins and thermoplastic epoxy resins are other names of phenoxy resins and correspond to the phenoxy resins of the present invention.

The average molecular weight of the phenoxy resin is usually 10,000 to 200,000, preferably 20,000 to 100,000, and more preferably 30,000 to 80,000 as a weight average molecular weight (Mw). be. If the Mw is too low, the strength of the FRTP molding will be poor, and if it is too high, the workability and workability will tend to be poor. In addition, Mw is a value measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve.

The hydroxyl group equivalent (g/eq) of the phenoxy resin is usually 50-1000, preferably 50-750, particularly preferably 50-500. If the hydroxyl group equivalent is too low, the number of hydroxyl groups increases and the water absorption rate increases, so there is a concern that the mechanical properties may deteriorate. If the hydroxyl group equivalent is too high, the number of hydroxyl groups is small, and the wettability with the reinforcing fiber base material, particularly carbon fibers, is lowered.

A phenoxy resin having a glass transition point (Tg) of 65°C to 160°C is suitable, preferably 70°C to 150°C. If the glass transition point is lower than 65° C., moldability is improved, but problems such as deterioration of powder or pellet storage stability due to blocking and stickiness during preforming (deterioration of tackiness) occur. If the temperature is higher than 160°C, the melt viscosity becomes high and the moldability and the filling property of the reinforcing fiber base material are deteriorated. As a result, higher temperature press molding is required. The glass transition point of the phenoxy resin is measured in the range of 20 to 280° C. with a temperature rising condition of 10° C./min using a differential scanning calorimeter, and is a numerical value obtained from the peak value of the second scan.
The melt viscosity of the phenoxy resin is preferably 3,000 Pa·s or less in a temperature range of Tg (∼160°C) or higher. It is more preferably 500 Pa·s or less, still more preferably 300 Pa·s or less. On the other hand, the lower limit of the melt viscosity is preferably 10 Pa·s or more, more preferably 50 Pa·s or more. In addition, since the phenoxy resin does not have a melting point (Tm), the melt viscosity changes gradually according to the temperature.

The phenoxy resin is not particularly limited as long as it satisfies the predetermined physical properties described above. YP-55U), bisphenol F type phenoxy resin (for example, product name Phenotote FX-316 manufactured by Nippon Steel Chemical & Materials Co., Ltd.), copolymerized phenoxy resin of bisphenol A and bisphenol F (for example, Nippon Steel Chemical & Materials Co., Ltd. (product name YP-70 manufactured by Nippon Steel Chemical & Materials Co., Ltd.), or special phenoxy resins (for example, product names Phenotote YPB-43C, FX293 manufactured by Nippon Steel Chemical & Materials Co., Ltd.), etc. These can be used alone or in combination of two or more. can be used.

The second thermoplastic resin (B) is selected from any one of the group consisting of polyamide resin (B-1), polycarbonate resin (B-2) and polyester resin (B-3), and mixtures thereof may be

Polyamide resins are thermoplastic resins whose main chain is composed of repeating amide bonds, and are obtained by ring-opening polymerization of lactams, co-condensation polymerization of lactams, dehydration condensation of diamines and dicarboxylic acids, and the like.

Polyamide resins are all-aliphatic polyamide resins (e.g., nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, etc.), also called nylon whose main chain consists of an aliphatic skeleton, and aromatics are contained in the main chain. Semi-aliphatic polyamide resin or semi-aromatic polyamide resin (for example, nylon 6I, nylon 6T, nylon 9T, nylon M5T, nylon MXD6, etc.), and wholly aromatic also called aramid whose main chain is composed only of an aromatic skeleton group polyamide resin [Kevlar, Nomex (manufactured by Toray DuPont Co., Ltd.), Twaron, Conex (manufactured by Teijin Limited)]. Although any of these can be used in the present invention, it is preferable to use a fully aliphatic polyamide resin and/or a semi-aliphatic (semi-aromatic) polyamide resin. A fully aliphatic polyamide resin is more preferable, and a fully aliphatic polyamide resin called nylon 6 (polyamide 6) obtained by ring-opening polymerization of ε-caprolactam is most preferable.

The polyamide resin preferably has a melting point or glass transition point of 180°C or higher and a melt viscosity of 1,000 Pa·s or lower at a temperature of 250°C or higher. It is preferable to use one having a melting point or glass transition point of 200° C. or higher and a melt viscosity of 1000 Pa·s or lower at 200 to 350° C.

The polyamide resin preferably has a weight average molecular weight (Mw) of 10,000 or more, more preferably 25,000 or more. By using a polyamide resin with Mw of 10,000 or more, good mechanical strength of the molded article is ensured.

The polycarbonate resin (B-2) blended with the phenoxy resin (A) is a thermoplastic resin obtained by reacting a dihydroxy compound with phosgene or carbonic acid diester.
The polycarbonate resin preferably used in the present invention is solid at room temperature and preferably has a melt viscosity at 280°C of 3,000 Pa s or less, more preferably 2,000 Pa s or less, and still more preferably. It is 1,500 Pa·s or less. If the melt viscosity exceeds 3,000 Pa·s, the fluidity of the resin during molding is lowered, and the resin cannot spread sufficiently, causing voids, which is not preferable.

Among polycarbonate resins, aromatic polycarbonate resins obtained using aromatic dihydroxy compounds as raw materials are preferable in consideration of compatibility with bifunctional epoxy resins or phenoxy resins. Examples of aromatic dihydroxy compounds include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2, 2-bis(4-hydroxyphenyl)butane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis( 4-hydroxyphenyl-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-tert-butylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis (4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylsulfoxide , 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl ) propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, and the like. These can be used alone or in combination of two or more.

The weight-average molecular weight (Mw) of the polycarbonate resin is not particularly limited, and from the viewpoint of ensuring the mechanical strength of the molded article, it is preferably in the range of 10,000 to 250,000, preferably 15,000 to 200,000. is more preferable. If the Mw of the polycarbonate resin is too low, the molded article may have poor mechanical properties and heat resistance, and if it is too high, workability and workability will tend to be poor. Mw is measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.

The glass transition temperature (Tg) of the polycarbonate resin is preferably 200° C. or lower. It is preferably 140°C to 170°C, more preferably 145°C to 165°C. When the Tg of the polycarbonate resin is higher than 200° C., the melt viscosity increases, and when the resin composition of the present embodiment is applied to FRP, for example, it is difficult to impregnate a reinforcing fiber base material without defects such as voids. Become. On the other hand, the lower limit of Tg is not particularly limited as long as there is no problem with workability, but it is preferably about 140° C. or higher.
As for the melting point (Tm) of the polycarbonate resin, although it does not show a very clear Tm, it is preferably in the range of 200 to 300°C, preferably 220 to 280°C, more preferably 240 to 260°C. If the melting point is less than 200°C, the cross-linking reaction may start in a state in which the phenoxy resin is insufficiently impregnated into the reinforcing fiber base material, for example, when applied to FRP. A molding machine with higher temperature specifications is required.

The polyester resin (B-3) suitable for the present invention is an aromatic polyester resin having a melting point of 200°C or higher obtained by polycondensation of a dicarboxylic acid compound and a diol, and may be a semi-aromatic polyester resin.

Examples of aromatic polyester resins having polycondensates of these dicarboxylic acid compounds and diols as structural units include polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, polypropylene isophthalate, polybutylene isophthalate, polybutylene naphthalate, poly Examples include cyclohexanedimethylene terephthalate, and examples of copolymers include aromatic polyester resins such as polypropylene isophthalate/terephthalate, polybutylene isophthalate/terephthalate, polypropylene terephthalate/naphthalate, and polybutylene terephthalate/naphthalate. From the viewpoint of further improving mechanical properties and heat resistance, in the present invention, a polymer or copolymer having a polycondensate of an aromatic dicarboxylic acid compound and an aliphatic diol as a main structural unit is more preferable, and terephthalic acid and naphthalenedicarboxylic acid Polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene whose main structural unit is a polycondensate of a dicarboxylic acid compound selected from ethylene glycol, propylene glycol and an aliphatic diol selected from 1,4-butanediol Aromatic polyester resins such as terephthalate, polyethylene isophthalate/terephthalate, polypropylene isophthalate/terephthalate, polybutylene isophthalate/terephthalate, polybutylene terephthalate/decanedicarboxylate, polybutylene terephthalate/polytetramethylene glycol are particularly preferred, and polyethylene terephthalate , polybutylene terephthalate, polypropylene terephthalate or polybutylene naphthalate are most preferred.

The polyester resin preferably has a weight average molecular weight (Mw) of 8,000 or more in order to further improve mechanical properties. Further, when the weight average molecular weight (Mw) is 500,000 or less, the balance between mechanical properties and moldability is excellent, which is preferable. The weight average molecular weight is more preferably 300,000 or less, still more preferably 250,000 or less.

The melting point or glass transition point of the polyester resin is 200°C or higher, preferably 200 to 300°C or lower, more preferably 220 to 260°C. The higher the melting point, the easier it is to improve heat resistance, strength, and rigidity. or decrease.
The melt viscosity is preferably in the range of 100 to 2000 Pa·s at temperatures above the melting point. By using an aromatic polyester resin having a melt viscosity within this range at a temperature equal to or higher than the melting point, the continuous fiber sheet can be impregnated with the resin composition just enough when molding the fiber-reinforced plastic molding material. .

A mixture of crosslinkable resins is a resin composition that can develop a three-dimensional crosslinked structure mainly using the reactive functional groups of the side chains of the polymer chains, regardless of the presence or absence of a crosslinker. Examples of such a resin composition include a composition comprising a phenoxy resin (A), an epoxy resin (C) and an acid anhydride (D), a composition comprising a phenoxy resin (A) and a polycarbonate resin (B-2), Alternatively, a composition comprising a phenoxy resin (A) and a polyester resin (B-3) is exemplified.

In the case of a composition comprising a phenoxy resin (A), an epoxy resin (C), and a cross-linking agent (D), the phenoxy resin (A) can form a three-dimensional cross-linked structure using the secondary hydroxyl groups of the side chains. Acid anhydrides, isocyanate compounds, caprolactam and the like are known as cross-linking agents.
In order to achieve the object of the present invention, only the phenoxy resin (A) and the cross-linking agent (D) may be used. D) is preferably used in combination.

Epoxy resin (C) is preferably a bifunctional or higher epoxy resin, bisphenol A type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. Epotote YD-011, Epotote YD-7011, Epotote YD-900), bisphenol F type epoxy Resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. Epototo YDF-2001), diphenyl ether type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. YSLV-80DE), tetramethylbisphenol F type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. YSLV-80XY), bisphenol sulfide type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. YSLV-120TE), hydroquinone type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. Epototo YDC-1312), phenol novolac type epoxy resin, ( For example, Nippon Steel & Sumikin Chemical Co., Ltd. Epotote YDPN-638), ortho cresol novolac type epoxy resin (e.g., Nippon Steel & Sumikin Chemical Co., Ltd. Epotote YDCN-701, Epotote YDCN-702, Epotote YDCN-703, Epotote YDCN-704), Aralkyl naphthalenediol novolak type epoxy resin (eg, ESN-355 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), triphenylmethane type epoxy resin (eg, EPPN-502H manufactured by Nippon Kayaku Co., Ltd.), etc., but these are not limited. However, two or more of these may be mixed and used.

In order to store the matrix resin composition as a powder, the epoxy resin (C) is also preferably solid at room temperature, has a melting point of 75°C to 145°C, and a melt viscosity of 1.0 Pa· at 160°C. A crystalline epoxy resin having a viscosity of s or less is preferred. If the viscosity exceeds 1.0 Pa·s, the matrix resin composition will not fill the reinforcing fiber base material with poor homogeneity, which is not preferable.
Since the melt viscosity of the crystalline epoxy resin is much lower than that of the solid epoxy resin, the impregnating property of the matrix resin can be improved by blending the crystalline epoxy resin. Therefore, it is suitable for combined use with a phenoxy resin having a high melt viscosity.

The epoxy resin (C) should be blended in an amount of 5 to 85 parts by weight with respect to 100 parts by weight of the phenoxy resin (A). It is preferably 9 to 83 parts by weight, more preferably 10 to 70 parts by weight. If the amount of the epoxy resin (C) exceeds 85 parts by weight, it takes time to cure the epoxy resin, making it difficult to obtain the strength required for demolding in a short period of time, and the recyclability of the FRP decreases. On the other hand, if the amount of the epoxy resin (C) is less than 5 parts by weight, the effect of the epoxy resin will not be obtained, and the cured product of the matrix resin composition will hardly exhibit a glass transition temperature (Tg) of 160° C. or higher. Become.

The cross-linking agent (D) is not particularly limited as long as it reacts with the secondary hydroxyl group of the side chain of the phenoxy resin to form a three-dimensional cross-linked structure, and may be an acid dianhydride, an isocyanate compound, caprolactam, or the like. It is desirable to use it together with the epoxy resin (C) because there is a risk that the cross-linking reaction will proceed too much or the cross-linking distance will be shortened and the resin composition will easily gel.
For this reason, acid dianhydrides, which are polyfunctional and have reactivity with the epoxy resin (C), are preferred. In particular, aromatic acid dianhydrides such as pyromellitic anhydride, 4,4'-oxydiphthalic anhydride, and bisphenol A fujiphthalic anhydride (BisDA) have many reaction points and can improve the crosslink density. It is particularly preferably used because the Tg of the crosslinked cured product is greatly improved.

The amount of the cross-linking agent (D) is usually in the range of 0.6 to 1.3 mol of the acid anhydride group per 1 mol of the secondary hydroxyl group of the phenoxy resin (A). It is preferably in the range of 0.9 to 1.3 mol, more preferably in the range of 0.9 to 1.1 mol. If the amount of acid anhydride groups is too small, the acid anhydride groups reactive with the secondary hydroxyl groups of the phenoxy resin (A) will be insufficient, resulting in a low cross-linking density and poor rigidity. The acid anhydride becomes excessive with respect to the secondary hydroxyl group of the unreacted acid anhydride, which adversely affects the curing properties and crosslink density. In addition to directly cross-linking the phenoxy resin with the acid anhydride group (COOH) of the cross-linking agent, it is thought that there are two forms of cross-linking the phenoxy resin via the epoxy resin. is consumed by the secondary OH of the phenoxy resin and the epoxy group of the epoxy resin, and almost no COOH remains in the cured product.

In the case of a composition comprising a phenoxy resin (A) and a polycarbonate resin (B-2) or an aromatic polyester resin (B-3), although both are thermoplastic resins, the resin composition is heated at 280° C. or higher, For example, by heating to a temperature within the range of 280 to 320° C., preferably 280 to 300° C., it exhibits a characteristic behavior of irreversibly hardening and thereafter becoming substantially infusible.
The curing mechanism in this case is not yet clear, but transesterification occurs between mainly secondary hydroxyl groups contained in the phenoxy resin and the ester groups of the polycarbonate resin or aromatic polyester resin, resulting in a bifunctional epoxy resin. It is presumed that the hardening is caused by forming crosslinks between chains or phenoxy resin chains and polycarbonate resin chains to take a three-dimensional network structure.

The matrix resin composition of the fiber-reinforced plastic material of the present invention may contain other thermoplastic resins, thermosetting resins, organic solvents, cross-linking agents, inorganic fillers, extender pigments, and colorants as long as the effect is not impaired. , antioxidants, UV inhibitors, flame retardants, flame retardant aids, etc. may also be blended.

The present invention also includes a reinforcing fiber plastic molding material (hereinafter referred to as "prepreg") obtained by impregnating a reinforcing fiber base material with the resin composition of the present invention to form a matrix resin.

The material of the reinforcing fiber base material impregnated with the resin composition serving as the matrix resin composition is not particularly limited, and examples thereof include carbon fiber, glass fiber, aramid fiber, alumina fiber, boron fiber, metal fiber, and basalt fiber. of inorganic or organic fibers can be used, and these may be used alone or in combination of two or more. Among them, PAN-based and pitch-based carbon fibers are preferably used from the viewpoint of high specific strength and high specific rigidity and weight reduction effect.
The reinforcing fibers may be a unidirectional reinforcing fiber substrate made of continuous fibers, a cloth material such as plain weave or twill weave, or a nonwoven fabric made of discontinuous reinforcing fibers. In general, the springback phenomenon is conspicuous in non-woven fabric substrates using discontinuous reinforcing fibers, such as short fibers. In some cases, the same springback phenomenon occurs as in the case of nonwoven fabric substrates.

The sizing treatment of the reinforcing fiber base material is optional. Since the resin composition of the present invention has a good affinity with reinforcing fibers, the matrix resin and reinforcing fibers are strongly bonded without sizing treatment. Treated reinforcing fiber substrates can also be used.

The FRP molding material of the present invention is obtained by adhering or impregnating a reinforcing fiber base material with a resin composition that serves as a matrix resin using a known method. In this case, it is preferable to use a method that does not use a solvent.
As such a method, for example, a method of melt-impregnating a resin composition formed into a film into a reinforcing fiber base material made of continuous fibers (press-in method, film stack method), or a method of blending continuous fibers spun with a resin composition and reinforcing fibers. a method (commingle method), and a method of spraying and coating a powdered resin composition on a reinforcing fiber substrate (powder coating method, powder coating method). Among them, the commingle method and the powder coating method do not easily break the reinforcing fibers when producing FRP molding materials, and are flexible and breathable, so internal air bubbles are less likely to occur even if they are laminated in multiple layers. This is a more preferable method because an FRP molding material can be obtained.
In addition, when the reinforcing fibers are short fibers, a method of impregnating a reinforcing fiber base material processed into a nonwoven fabric with a resin composition in the form of a powder, a molten state, or an emulsion; A method of depositing or assembling while stirring and mixing together to form a prepreg is exemplified.

The adhesion amount of the matrix resin (resin ratio: RC) in the FRP molding material using the thermoplastic resin composition of the present invention is 20 to 50% by weight, preferably 25 to 45%, more preferably 25%. ~40%. If the RC exceeds 50%, the mechanical properties such as tensile and flexural modulus of FRP deteriorate, and if it is less than 10%, the amount of resin adhered is extremely small, making it impossible to impregnate the matrix resin inside the base material. There is a concern that both the thermophysical properties and mechanical properties will become low.

An FRP molded product can be easily produced by heating and pressurizing the FRP molding material using the thermoplastic resin composition of the present invention singly or by laminating a plurality of them. That is, it is possible to simultaneously perform shaping and complete impregnation of the reinforcing fiber base material with the matrix resin by pressure molding by hot pressing. As long as molding using FRP molding materials is heat and pressure molding, various molding methods such as autoclave molding and hot press molding using a mold can be used as appropriate according to the size and shape of the desired FRP molded product. You can choose to implement it.

The molding temperature in the heat and pressure molding is, for example, 160 to 260°C, preferably 180 to 250°C, more preferably 180 to 240°C. If the molding temperature exceeds the upper limit temperature, excessive heat is applied, which may result in excessive outflow of resin or thermal deterioration. and productivity deteriorates. On the other hand, when the temperature is lower than the lower limit temperature, the melt viscosity of the matrix resin is high, so the impregnating property of the matrix resin into the reinforcing fiber base material is deteriorated. The molding time is usually 30 to 60 minutes.

The FRTP molded article obtained from the fiber-reinforced plastic molding material of the present invention hardly deforms even when subjected to heat of nearly 300°C, and its rigidity at high temperatures is greatly improved. It can be widely and suitably used not only for bodies and parts, but also as molded parts for automobiles and industrial equipment that require higher heat resistance, such as engine covers.

The present invention will be explained more specifically by showing examples below, but the present invention is not limited to the description of these examples. Various physical property tests and measurement methods in Examples and Comparative Examples are as follows.

Average particle size (D50)
The average particle size was measured by a laser diffraction/scattering particle size distribution analyzer (Microtrac MT3300EX, manufactured by Nikkiso) when the cumulative volume was 50% on a volume basis.

Melt viscosity (measurement of ρ _220≧ , ρ _min )
Using a rheometer (manufactured by AntonPaar), a matrix resin composition (MT resin) processed into a film of 150 mm square and 0.4 mm thick was sandwiched between parallel plates, and the temperature was raised and then lowered at 5°C/min. , frequency: 1 Hz, load strain: 0.2%, various melt viscosities of the MT resin were measured when the temperature was raised from room temperature to 280°C and when the temperature was lowered from 280°C to 70°C.
In Table 1, “ρ _{220 ≧} ” indicates the minimum value of melt viscosity in the temperature range of 220° C. or lower when the temperature is lowered, and “ρ ₍₂₂₀₊₎ ” indicates the temperature at 220° C. when the temperature is raised from room temperature to 280° C. The melt viscosity is reached when the temperature is reached, and “ρ _min ” indicates the minimum value of the melt viscosity when the temperature is raised.
(Measurement of ρ _Tg+100 and ρ _Tm-5 )
Using a rheometer (manufactured by Anton Paar), about 100 mg of pulverized material of the matrix resin composition exuded during press molding of the prepreg was sandwiched between parallel plates, and the temperature was raised at 5 ° C./min, frequency: 1 Hz, load Various melt viscosities were measured when the temperature was raised from room temperature to 280° C. under the condition of strain: 0.2%.
In Table 1, “ρ _(Tg+100) ” indicates the melt viscosity at the glass transition point +100° C. of the resin that is the main component of the resin composition, and “ρ _(Tm−5) ” is the main component of the resin composition. It shows the melt viscosity at the melting point of −5° C. of the resin.

Confirmation of reactivity Using a rheometer (manufactured by AntonPaar), a powdery matrix resin composition (MT resin) was sandwiched between parallel plates, heated to 280°C at a rate of 5°C/min, and then heated to 280°C for 30 minutes. While holding, the melt viscosity of the MT resin was measured under the conditions of frequency: 1 Hz and load strain: 0.2%. Legends for the measurement results (Δρ) shown in Table 1 are as follows. The reference melt viscosity is the melt viscosity when the temperature reaches 280°C.
A: Increase in melt viscosity of 5 times or more was confirmed during the holding period at 280°C.
◯: The melt viscosity was confirmed to increase by a factor of 2 or more during the holding period at 280°C. △: The melt viscosity was confirmed to be less than doubled during the holding period at 280°C.

Glass transition temperature (Tg)
The composition for matrix resin was compression-molded in a mold, and a test piece having a thickness of 2 mm and a diameter of 6 mm was cut out using a diamond cutter. The test piece is measured using a dynamic viscoelasticity measuring device (Perkin Elmer DMA 7e) at a temperature increase of 5 ° C./min in the range of 25 to 280 ° C. The maximum peak of tan δ obtained is taken as the glass transition point. and

Melting point (Tm)
It was measured using a differential scanning calorimeter (DSC) based on JIS K 7121:1987 Plastic transition temperature measurement method.

Evaluation of springback (S/B) property The springback of the molded product is determined by the amount of change in the thickness of the molded product after being subjected to a heat history of 200°C for 30 minutes in an air oven and the thickness of the molded product at 25°C. did.
The thickness was measured using a micrometer and the average value was used to calculate the amount of springback according to the following formula.
S/B amount (%) = dimensional thickness of molded body after heat history/thickness of molded body at 25°C x 100

FRP Bending Test Mechanical properties (bending strength and bending elastic modulus) of the obtained metal-FRP composite were measured according to JIS K 7074:1988 Fiber-reinforced plastic bending test method.
The FRP molding material was laminated so that the thickness after molding was 1.0 mm, and heat-pressed under the conditions shown in each example and comparative example. Then, a sample of the FRP composite for the bending test was prepared by shaping it into a width of 15 mm and a length of 60 mm using a diamond cutter.
In the measurement, as a pretreatment, the sample was placed in an air oven set at 220° C. for 10 minutes, then taken out and allowed to cool to room temperature.

Measurement of deflection temperature under load The deflection temperature under load of the fiber-reinforced plastic to be the test piece was measured with reference to JIS K 7191 Plastics - Determination of deflection temperature under load.

The resin components constituting the thermoplastic resin composition are shown below.
Phenoxy resin (A)
Phenotote YP-50S (bisphenol A type manufactured by Nippon Steel & Sumikin Chemical, Mw = 40,000, hydroxyl equivalent = 284 g / eq), melt viscosity at 250 ° C. = 90 Pa s
Polyamide resin (B-1)
CM1017 (manufactured by Toray, polyamide 6), melt viscosity at 250 ° C. = 125 Pa s, Tm = 225 ° C.
Polycarbonate resin (B-2)
Iupilon S3000F (manufactured by Mitsubishi Engineering-Plastics Co., Ltd., Mw = 36,000), melt viscosity at 280 ° C. = 1,000 Pa s, Tg = 160 ° C., Tm = 230 to 260 ° C.
Aromatic polyester resin (B-3)
NEH-2070 (manufactured by Unitika Ltd., polyethylene terephthalate), melt viscosity at 270°C = 914 Pa s, Tg = 77°C, Tm = 250°C
Epoxy resin (C)
YSLV-80XY (tetramethylbisphenol F type manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent = 192, Tm = 72 ° C.)
Crosslinking agent (D)
BisDA (bisphenol A, diphthalic anhydride, acid anhydride equivalent: 260, melting point: 184°C, SABIC)

Creation example 1
50 parts by weight of YP-50S and 50 parts by weight of S3000F are prepared, each pulverized and classified into a powder having an average particle diameter D50 of 100 μm or less, and dry-blended with a dry powder mixer to form a resin composition. Item E1 was prepared.

Creation example 2
77 parts by weight of YP-50S and 23 parts by weight of YSLV-80XY are prepared, pulverized and classified, respectively, and the average particle diameter D50 is 100 μm or less. Resin composition E2 was prepared by blending in equal amounts and dry-blending using a dry powder mixer.

Creation example 3
Prepare 50 parts by weight of YP-50S and 50 parts by weight of CM1017, pulverize and classify each to powder having an average particle diameter D50 of 100 μm or less, and use a dry powder mixer (manufactured by Aichi Denki Co., Ltd., Rocking Resin composition E3 was prepared by dry blending with a mixer).

Creation example 4
Prepare 70 parts by weight of YP-50S and 30 parts by weight of NEH-2070, pulverize and classify each to powder with an average particle diameter D50 of 100 μm or less, and use a dry powder mixer (manufactured by Aichi Denki Co., Ltd. A resin composition E4 was prepared by dry blending with a rocking mixer).

Example 1
Short fibrous resin fibers (fiber diameter 29 μm, average fiber length 50 mm) of the resin composition E1 as the matrix resin, and short fibrous carbon fibers (manufactured by Mitsubishi Chemical Corporation, TR50S, fiber diameter 7 μm, average fiber length 50 mm) was prepared and the mixing ratio was set to 50/50. A mixture of these is put into a pretreatment machine, put into a carding machine through a pretreatment process, and a web in which the short fibrous resin fibers and short fibrous carbon fibers of the resin composition E2 are uniformly mixed is produced. did. This web was entangled and integrated by a needle punching method to produce a CFRP prepreg made of a random mat having a thickness of 7 mm.
The obtained CFRP prepreg was laminated in five layers and pressed at 5 MPa for 10 minutes with a pressing machine heated to 280° C. to produce a CFRP molded body.

Example 2
The resin composition E1 obtained in Preparation Example 1 was sprayed with SA3202 (manufactured by Sakai Ovex Co., Ltd., open fiber open carbon fiber cloth material made by Sakai Ovex Co., Ltd.) from which the sizing agent was removed as a reinforcing fiber base material at a charge of 60 kV in an electrostatic field. Powder coating was performed at an air flow rate of 60 L/min so that Vf after molding was 60%. After that, the resin composition was heated and melted in an oven at 250° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg having a thickness of 0.9 mm and a resin ratio (RC) of 30%.
The obtained CFRP prepreg was pressed at 5 MPa for 10 minutes with a press heated to 280° C. to produce a CFRP molded body.

Example 3
A short fibrous carbon fiber base prepared by a needle punch method using the resin composition E2 obtained in Preparation Example 2 as the matrix resin and recycled carbon fiber (manufactured by iCarbon Co., Ltd., average fiber length 50 mm) as the reinforcing fiber. A material (400 g/m ² basis weight) is prepared, and powder coating is performed using a powder coating device under the conditions of an electric charge of 60 kV and an air blowing rate of 60 L/min so that Vf after molding is 60%. did After that, the resin composition was heated and melted in an oven at 250° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg composed of a random mat having a thickness of 7 mm.
The obtained CFRP prepreg was laminated in five layers, and pressed at 5 MPa for 10 minutes with a press heated to 240° C. to produce a CFRP molded body.

Example 4
The resin composition E2 obtained in Preparation Example 2 was used as a reinforcing fiber base material with SA3202 from which the sizing agent was removed, and the Vf after molding was 60% under the conditions of an electric charge of 60 kV and a blown air amount of 60 L / min in an electrostatic field. I powder coated it to look like this. After that, the resin composition was heated and melted in an oven at 250° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg having a thickness of 0.9 mm and a resin ratio (RC) of 30%.
The obtained CFRP prepreg was pressed at 5 MPa for 10 minutes with a press heated to 200° C. to produce a CFRP compact.

Example 5
The resin composition E1 obtained in Preparation Example 1 was used as a reinforcing fiber base material with SA3202 from which the sizing agent was removed, and the Vf after molding was 60% under the conditions of an electric charge of 60 kV and a blown air amount of 60 L / min in an electrostatic field. I powder coated it to look like this. After that, the resin composition was heated and melted in an oven at 250° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg having a thickness of 0.9 mm and a resin ratio (RC) of 30%.
The obtained CFRP prepreg was pressed at 5 MPa for 10 minutes with a press heated to 280° C. to produce a CFRP molded body. After cooling the obtained CFRP molded article X1, the mechanical strength (stress at break and elastic modulus) was measured. The results are shown in Table 2.

Example 6
The resin composition E4 obtained in Preparation Example 4 was used as a reinforcing fiber base material with SA3202 from which the sizing agent was removed, and the Vf after molding was 60% under the conditions of an electric charge of 60 kV and a blown air amount of 60 L / min in an electrostatic field. I powder coated it to look like this. After that, the resin composition was heated and melted in an oven at 270° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg having a thickness of 0.9 mm and a resin ratio (RC) of 30%.
The obtained CFRP prepreg was pressed at 2 MPa for 15 minutes with a press heated to 270° C. to produce a CFRP molded body. After cooling the obtained CFRP molded article X1, the mechanical strength (stress at break and elastic modulus) was measured. The results are shown in Table 2.

Comparative example 1
CFRP with a thickness of 0.9 mm and a resin ratio (RC) of 30% in the same manner as in Example 1, except that YP-50S that was pulverized and classified so that D50 was 100 μm or less was used alone. A prepreg was produced.
The obtained CFRP prepreg was pressed at 5 MPa for 10 minutes with a press heated to 280° C. to produce a CFRP molded body. After cooling the obtained CFRP molded article X1, the mechanical strength (stress at break and elastic modulus) was measured. The results are shown in Table 2.

Comparative example 2
YP-50S pulverized and classified so that D50 is 100 μm or less and SA3202 from which the sizing agent is removed is used as a reinforcing fiber base material, and in an electrostatic field, under the conditions of an electric charge of 60 kV and a blown air amount of 60 L / min, Vf after molding is Powder coating was applied so as to be 60%. After that, the resin composition was heated and melted in an oven at 250° C. for 3 minutes to thermally bond the resin composition to the carbon fibers, thereby producing a CFRP prepreg having a thickness of 0.9 mm and a resin ratio (RC) of 30%.
The obtained CFRP prepreg was pressed at 5 MPa for 10 minutes with a press heated to 280° C. to produce a CFRP molded body. After cooling the obtained CFRP molded article X1, the mechanical strength (stress at break and elastic modulus) was measured. The results are shown in Table 2.

Comparative example 3
CFRTP prepreg having a resin ratio (RC) of 30% and A CFRTP molded article was produced and the mechanical strength (stress at break and elastic modulus) was measured.

CFRP prepared by using the resin composition of the present invention as a matrix resin has a small amount of springback and a high deflection temperature under load even when placed in a high-temperature environment, compared to the case where the constituent material is used alone. It is clear from the results shown in Table 1 that
In this way, by setting the melt viscosity parameter of the resin composition to be the matrix resin of CFRP within the scope of the claims, it is possible to express high heat resistance above the processing temperature while using a thermoplastic resin as the main component. Even if it is not a highly heat-resistant resin that requires high-temperature processing such as super engineering plastics, it exhibits performance comparable to that, so it can be used in automotive materials and aerospace fields where heat resistance and mechanical strength in hot conditions are required. It can be used as a useful material for surfaces and the like.

The resin composition of the present invention is useful as a FRTP material, particularly a CFRTP material, for structural members used in harsh environments such as automobiles, aviation and space.

Claims

A resin composition containing a thermoplastic resin that becomes a matrix resin of a fiber-reinforced plastic after being impregnated into a reinforcing fiber base material,
50 wt% or more of the entire resin composition is a thermoplastic resin containing a phenoxy resin as an essential component,
A thermoplastic resin composition characterized by having a melt viscosity exceeding 10000 Pa·s in a temperature range of 220°C or lower when the temperature is raised from room temperature to 280°C using a rheometer and then cooled to room temperature again.
The matrix resin contains 30 wt% or more and 70 wt% or less of the phenoxy resin (A), and the remainder is any one of the group consisting of the polyamide resin (B-1), the polycarbonate resin (B-2) and the polyester resin (B-3). The thermoplastic resin composition according to claim 1, which is a mixture with a second thermoplastic resin (B-1 to B-3) selected from the above.
The thermoplastic resin composition according to claim 1, which contains an epoxy resin (C) together with a thermoplastic resin as a matrix resin.
The thermoplastic resin composition according to claim 1, wherein the resin composition serving as the matrix resin exhibits mutual reactivity or crosslinkability.
A fiber-reinforced plastic molding material in which a reinforcing fiber base material is impregnated with the thermoplastic resin composition according to any one of claims 1 to 4.
A molded article obtained by molding the fiber-reinforced plastic molding material according to claim 5.
6. The molded article according to claim 5, wherein the change rate of the thickness of the fiber-reinforced plastic is more than 0% and less than 10% when left to stand for 10 minutes in the same thermal environment as the temperature during molding and then allowed to cool to room temperature.