JP6676222B2 - Sizing agent for reinforcing fiber and its use - Google Patents

Description

  The present invention relates to a sizing agent for reinforcing fibers and use thereof.

As a carbon fiber bundle using a polyolefin as a matrix resin, a polyolefin resin obtained by acid-modifying a polyolefin resin is generally used as a sizing agent (Patent Document 1).
However, the acid-modified polyolefin has a very hard and brittle film and is inferior in fiber protection. In addition, since the sizing agent layer is broken due to deformation and the like due to poor flexibility, there is a problem that the physical properties of the molded product are not preferable.

JP-A-2013-131889

  In view of such conventional background art, an object of the present invention is to provide a sizing agent for reinforcing fibers having excellent physical properties of a molded product, and a carbon fiber bundle to which the sizing agent is attached.

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a sizing agent for reinforcing fibers containing a specific component can solve the above problems.
That is, the sizing agent for reinforcing fibers of the present invention contains the component (A) which is an acrylic resin, the rubber component (B), and the component (C) which is a liquid rosin ester resin.
It is preferable that the weight ratio of the component (C) to the non-volatile content of the sizing agent is 20 to 80% by weight.
Preferably, the non-volatile content of the fiber sizing agent is solid at 20 ° C.
The viscosity of the component (C) at 50 ° C. and 1 atm is preferably 500,000 mPa · s or less.

The reinforcing fiber strand of the present invention is obtained by adhering the reinforcing fiber sizing agent to a raw material reinforcing fiber strand.
The fiber-reinforced composite material of the present invention includes a polyolefin resin and the above-mentioned reinforcing fiber strand.

  The carbon fiber bundle to which the sizing agent for reinforcing fibers of the present invention is attached has excellent physical properties of a molded product. The fiber-reinforced composite material of the present invention is excellent in the physical properties of the molded product.

  The sizing agent for reinforcing fibers of the present invention will be described in detail below.

[Component (A)]
Component (A) is an acrylic resin. The component (A) plays a role in tack development in the sizing agent for reinforcing fibers of the present invention. The reason why the component (A) exerts the effect of tack development is not clear, but it is presumed to be due to viscoelastic behavior.
As a raw material of the acrylic resin, other monomers having a polymerizable unsaturated group can be used, if necessary, in addition to the acrylic monomer.
In the present invention, the notation of “(meth) acryl” indicates one or both of “acryl” and “methacryl”.
Examples of the acrylic monomer include (meth) acrylic acid-based compounds.
Examples of the (meth) acrylic acid-based compound include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, glycidyl (meth) acrylate, di (meth) Diethylene glycol acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, di (meth) acrylate Serine, and the like.
Further, the monomer having a polymerizable unsaturated group may be used within a range that does not affect the performance. For example, styrene, α-methylstyrene, paramethylstyrene, chloromethylstyrene, vinyl acetate, crotonic acid, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3-hexenoic acid, 5-hexenoic acid, 2-heptene Acid, 3-heptenoic acid, 6-heptenoic acid, 3-octenoic acid, 7-octenoic acid, 2-nonenoic acid, 3-nonenoic acid, 8-nonenoic acid, 9-decenoic acid, 10-undecenoic acid, 3-allyl Monomers such as oxypropionic acid, allyloxyvaleric acid, ω-carboxy-polycaprolactone monoacrylate, itaconic acid (anhydride), maleic acid (anhydride), and fumaric acid are exemplified.

The acrylic resin (A) is obtained by, for example, reacting the acrylic monomer and another monomer having a polymerizable unsaturated group in an organic solvent and / or water in the presence of a polymerization initiator at a temperature of 60 to 140 ° C. And radical polymerization is carried out. Examples of the organic solvent include aromatic solvents such as toluene and xylene; alicyclic solvents such as cyclohexanone; ester solvents such as butyl acetate and ethyl acetate; isobutanol, normal butanol, isopropyl alcohol, and sorbitol; Cellosolves such as propylene glycol monomethyl ether acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone can be used. These solvents can be used alone or in combination of two or more.

Examples of the polymerization initiator include azo compounds such as 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile) and azobiscyanovaleric acid; tert-butyl peroxy Organic peroxides such as pivalate, tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, benzoyl peroxide and tert-butyl hydroperoxide Oxides; inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate; These polymer initiators can be used alone or in combination of two or more. Further, it is preferable that the polymerization initiator is used in a range of 0.1 to 10% by mass based on the total amount of monomers serving as a raw material of the acrylic resin (A). As a method of dissolving or dispersing the acrylic resin (A) in an aqueous medium, a method of polymerizing the acrylic resin (A) in the aqueous medium, a method of mixing the acrylic resin (A) with the aqueous medium, A method of mixing the neutralized acrylic resin (A) with the aqueous medium is exemplified.

When neutralizing the acrylic resin (A), it is preferable to use a basic compound. Examples of these basic compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, and 2-amino. Organic amines such as ethanol and 2-dimethylaminoethanol; inorganic basic compounds such as ammonia, sodium hydroxide and potassium hydroxide; tetramethylammonium hydroxide, tetra-n-butylammonium hydroxide and trimethylbenzylammonium hydroxide; Secondary ammonium hydroxide and the like. Among these, it is preferable to use an organic amine and ammonia (may be aqueous ammonia). In addition, these basic compounds can be used alone or in combination of two or more.

[Component (B)]
Component (B) is a rubber. The component (B) plays a role in improving adhesion to a matrix in the sizing agent for reinforcing fibers of the present invention. The reason why the component (B) exerts the effect of improving the adhesion to the matrix is not clear, but it is presumed that the component (B) has a high affinity for the matrix.
As the component (B), for example, a vinylpyridine-styrene-butadiene copolymer, a modified product of a vinylpyridine-styrene-butadiene copolymer modified with a carboxyl group, a styrene-butadiene copolymer, and a modification thereof Products, acrylonitrile-butadiene and modified products thereof, natural rubber, chloroprene rubber, butyl rubber, acrylate copolymer latex, and the like, and two or more types may be used. Among them, styrene butadiene rubber and natural rubber are preferred.

[Component (C)]
Component (C) is a liquid rosin ester resin. The component (C) plays a role in enhancing the affinity with the matrix resin in the sizing agent for reinforcing fibers of the present invention. The reason why the component (C) exerts the effect of increasing the affinity with the matrix resin is not clear, but it is presumed to be due to the molecular structure and mobility. The “liquid” of the liquid rosin ester resin means that it has fluidity at normal temperature and normal pressure (1 atm, 30 ° C.). More specifically, when the composition is tilted by 45 °, the shape cannot be maintained for 10 minutes or more, which means that the shape changes.
More specifically, at 50 ° C. and 1 atm, the viscosity is usually 1,000,000 mPa · s or less, preferably 500,000 mPa · s or less, more preferably 400,000 mPa · s or less. , 300,000 mPa · s or less.
A preferred lower limit is 300,000 mPa · s. By satisfying the physical properties in this range, the affinity with the matrix resin is increased and the adhesion becomes easy.
The rosin ester is an esterified product derived from rosin, for example, a compound obtained by esterifying rosin with a hydroxyl group-containing compound.

  Rosin is a natural resin obtained from pine, and is a mixture containing abietic acid and its isomers in various ratios. Examples of the content other than abietic acid include dehydroabietic acid, dihydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, levopimaric acid, and parastric acid.

  The hydroxyl group-containing compound is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, Compounds having two hydroxyl groups such as pentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, dipropylene glycol and bisphenol A, glycerin, trimethylolethane and trimethylol Compounds having three hydroxyl groups such as propane; compounds having four hydroxyl groups such as pentaerythritol, sorbitan and diglycerin; and compounds having six hydroxyl groups such as sorbitol and dipentaerythritol.

  As the rosin ester (C), a compound obtained by further adding an alkylene oxide such as ethylene oxide or propylene oxide to the above esterified product can be used. The addition of these alkylene oxides can be performed according to a conventional method.

(Bundling agent for reinforcing fibers)
The weight ratio of the component (A) to the non-volatile content of the sizing agent is preferably 20 to 60% by weight, more preferably 20 to 50% by weight, further preferably 20 to 40% by weight, and particularly preferably 20 to 30% by weight. preferable. If it is less than 20% by weight, the tackiness may be insufficient, and if it is more than 80% by weight, the tackiness may be too strong and fluff may be generated in the process.
The weight ratio of the component (B) to the non-volatile content of the sizing agent is preferably 20 to 80% by weight, more preferably 20 to 70% by weight, further preferably 20 to 60% by weight, and particularly preferably 20 to 50% by weight. preferable. If it is less than 20% by weight, the adhesive strength may be insufficient, and if it exceeds 80% by weight, the texture may be too hard.
The weight ratio of the component (C) to the non-volatile content of the sizing agent is preferably 20 to 80% by weight, more preferably 30 to 80% by weight, still more preferably 30 to 70% by weight, and particularly preferably 40 to 60% by weight. preferable. If it is less than 20% by weight, the affinity with the matrix may be low, and if it is more than 80% by weight, the sizing agent becomes liquid and the adhesive strength may be insufficient.

  The sizing agent for reinforcing fibers of the present invention is preferable from the viewpoint of increasing the adhesive strength when the sizing agent has a non-volatile content of 20 ° C. and is solid. In addition, a solid here means having no fluidity at normal temperature and normal pressure (1 atm, 20 ° C.). More specifically, when the composition is tilted by 45 °, it means that the shape is maintained for 10 minutes or more, and the shape does not change. If the non-volatile content of the sizing agent is liquid at 20 ° C., the sizing agent in a liquid state is present in the solid carbon fiber, and the sizing agent functions as a lubricating oil. Due to slippage, the adhesive strength may be reduced. In this specification, the term "non-volatile content" refers to a completely dry component when a constant weight is reached by removing a solvent or the like by heat treatment at 105 ° C.

(Reinforcing fiber strand)
The reinforcing fiber strand of the present invention is obtained by adhering the reinforcing fiber sizing agent to a raw synthetic fiber strand, and is a reinforcing fiber for reinforcing a thermosetting resin or a thermoplastic matrix resin.

The method for producing a reinforcing fiber strand of the present invention is a production method including a sizing treatment step of adhering the above-described reinforcing fiber sizing agent to a raw material synthetic fiber strand and drying the resulting attached matter.
There is no particular limitation on the method of obtaining the deposit by adhering the reinforcing fiber sizing agent to the raw material synthetic fiber strand, but the stiffening fiber sizing agent is a kiss roller method, a roller dipping method, a spray method, or another known method. Any method may be used as long as it is attached to the raw material synthetic fiber strand. Among these methods, the roller dipping method is preferable because the reinforcing fiber sizing agent can be uniformly attached to the raw synthetic fiber strand.
There is no particular limitation on the method for drying the obtained attached matter, and for example, it can be dried by heating with a heating roller, hot air, a hot plate or the like.

  When attaching the reinforcing fiber sizing agent of the present invention to the raw material synthetic fiber strand, all the components of the reinforcing fiber sizing agent may be attached after mixing, or the components may be separately divided into two or more stages. May be attached. Further, within the range not impairing the effects of the present invention, epoxy resins, vinyl ester resins, thermosetting resins such as phenolic resins and / or polyolefin resins other than the polymer components of the present invention, nylon resins, polycarbonate resins, polyester resins, A thermoplastic resin such as a polyacetal resin, an ABS resin, a phenoxy resin, a polymethyl methacrylate resin, a polyphenylene sulfide resin, a polyetherimide resin, or a polyetherketone resin may be adhered to the raw synthetic fiber strand.

  The reinforcing fiber strand of the present invention is used as a reinforcing fiber of a composite material using various thermosetting resins or various thermoplastic resins as a matrix resin. The state may be performed.

The amount of non-volatile content of the reinforcing fiber sizing agent attached to the raw synthetic fiber strand can be appropriately selected, and may be set to a necessary amount for the synthetic fiber strand to have a desired function. It is preferably 0.1 to 20% by weight. In the synthetic fiber strand in the state of continuous fibers, the amount of the attached fiber is more preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, based on the raw material synthetic fiber strand. In the strand cut to a predetermined length, the content is more preferably 0.5 to 20% by weight, and still more preferably 1 to 10% by weight.
If the amount of the reinforcing fiber sizing agent attached is small, the effects of the present invention with respect to resin impregnation and adhesiveness are difficult to be obtained, and the sizing ability of the synthetic fiber strand is insufficient, which may result in poor handling. In addition, if the amount of the reinforcing fiber sizing agent attached is too large, the synthetic fiber strand becomes too rigid, which may make the handleability worse or may impair the resin impregnation during composite molding. Absent.

  The synthetic fibers of the (raw material) synthetic fiber strand to which the sizing agent for reinforcing fibers of the present invention can be applied include various inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, aramid fibers, polyethylene fibers, polyethylene terephthalate fibers, and polybutylene. Various organic fibers such as terephthalate fiber, polyethylene naphthalate fiber, polyarylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber, and polyketone fiber are exemplified. From the viewpoint of the physical properties of the obtained fiber-reinforced composite material, carbon fiber, aramid fiber, polyethylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene naphthalate fiber, polyarylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber And at least one selected from polyketone fibers.

(Fiber reinforced composite material)
The fiber-reinforced composite material of the present invention contains a thermosetting matrix resin or a thermoplastic matrix resin and the above-mentioned reinforcing fiber strand. Since the reinforcing fiber strand has been treated with the reinforcing fiber sizing agent of the present invention, the affinity for the reinforcing fiber strand and the thermoplastic matrix resin is good, and a fiber-reinforced composite material having excellent adhesiveness is obtained.

The fiber-reinforced composite material of the present invention contains a matrix resin and the above-mentioned reinforcing fiber strand. The reinforcing fiber strand is treated with the sizing agent of the present invention, and the sizing agent is uniformly attached thereto, the affinity with the reinforcing fiber strand and the matrix resin is improved, and a fiber-reinforced composite material having excellent adhesion is obtained. Further, thermal decomposition of the sizing agent during high temperature treatment can be suppressed, and inhibition of adhesion to the matrix resin due to the thermal decomposition can be suppressed. Here, the matrix resin refers to a matrix resin composed of a thermosetting resin or a thermoplastic resin, and may include one or more kinds. The thermosetting resin is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, an unsaturated polyester resin, a vinyl ester resin, a cyanate ester resin, and a polyimide resin. The thermoplastic resin is not particularly limited, and may be a polyolefin resin, a polyamide resin, a polycarbonate resin, a polyester resin, a polyacetal resin, an ABS resin, a phenoxy resin, a polymethyl methacrylate resin, a polyphenylene sulfide resin, a polyetherimide resin, Ether ketone resins and the like can be mentioned. Among these, thermoplastic resins are preferred from the viewpoint that the sizing agent of the present invention has a higher adhesiveness improving effect, and polyamide resins are more preferred. Here, the polyamide resin is a polymer compound having a plurality of amide groups in a main chain, which is synthesized from a dibasic fatty acid and a diamine, an ω-amino acid, a lactam or a derivative thereof, and is a homopolymer or a copolymer ( Copolymer). Further, a modified product having a substituent introduced into the main chain or the terminal may be used.
These matrix resins may be partially or wholly modified for the purpose of further improving the adhesion to the reinforcing fiber strands.

The method for producing the fiber reinforced composite material is not particularly limited, and a known method such as compound injection molding using chopped fibers or long fiber pellets, press molding using a UD sheet or a woven sheet, or other filament winding molding can be employed.
The content of the synthetic fiber strand in the fiber-reinforced composite material is not particularly limited, and may be appropriately selected depending on the type of fiber, form, type of thermoplastic matrix resin, and the like. It is preferably from 5 to 70% by weight, more preferably from 20 to 60% by weight.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples described here. In addition, the percentage (%) shown in the following Examples shows "weight%" unless there is particular limitation. The measurement of each characteristic value was performed based on the method shown below.

The components used in the examples are as follows.
(Component (A))
Acrylic resin A: (DIC Co., Boncoat W-386)
Acrylic resin B: (DIC Co., Boncoat AB-782-E)
(Component (B))
SBR resin (styrene butadiene rubber) (manufactured by DIC, Rack Star 8215A)
NR resin (natural rubber) (ULACOL, manufactured by Redex Corporation)
(Component (C))
Liquid rosin ester A: (Hariester SK-501NS, manufactured by Harima Chemicals Co., Ltd., viscosity of 300,000 mPa · s dried at 50 ° C., 1 atm 105 ° C. for 2 hours)
Liquid rosin ester B: viscosity of 45,000 mPa · s dried at 50 ° C., 1 atm at 105 ° C. for 2 hours

(Example 1)
The sizing agent for reinforcing fibers according to Example 1 was obtained by mixing and stirring 20% by weight of an acrylic resin A, 40% by weight of an SBR resin, and 40% by weight of a liquid rosin ester A.
(Examples 2 to 10, Comparative Examples 1 to 7)
A sizing agent for reinforcing fibers was produced in the same manner as in Example 1, and the same evaluation was performed.

<Droplet strength>
Using a composite material interface property evaluation device HM410 (manufactured by Toei Sangyo Co., Ltd.), the adhesiveness was evaluated by a microdroplet method.
Carbon fiber filaments are taken out from the carbon fiber strands produced in the examples and comparative examples, and set in a composite material interface property evaluation device. A drop of the polyamide resin T-663 (manufactured by Toyobo Co., Ltd.) melted on the apparatus was formed on the carbon fiber filament, and cooled sufficiently at room temperature to obtain a sample for measurement. The measurement sample was set in the apparatus again, the drop was sandwiched between the apparatus blades, the carbon fiber filament was run on the apparatus at a speed of 0.06 mm / min, and the maximum pulling load F when the drop was pulled from the carbon fiber filament was measured. .
The interface shear strength τ was calculated by the following equation, and the adhesiveness between the carbon fiber filament and the polyamide resin was evaluated.
Interfacial shear strength τ (unit: MPa) = F / πdl
(F: maximum drawing load d: diameter of carbon fiber filament l: particle diameter in drop pulling direction)

<Hand>
The sizing agent was attached to the untreated carbon fiber strands (fineness: 700 tex, number of filaments: 12,000) so that the amount of non-volatile components of the sizing agent was 2.0% by weight. The convergence of the obtained adhered carbon fiber strand (length: about 50 cm) was measured with a texture tester (HANDLE-O-METERHOM-2, manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd., slit width 10 mm).

As can be seen from Tables 1 and 2, the reinforcing fiber sizing agent of Examples 1 to 5 comprises a component (A) that is an acrylic resin, a rubber component (B), and a component (C) that is a liquid rosin ester resin. As a result, the adhesiveness can be improved.
On the other hand, only the component (B) (Comparative Example 1), only the component (A) (Comparative Example 2), only the component (C) (Comparative Example 3), when there is no component (A) (Comparative Example 4), When there is no B) (Comparative Example 5) and when there is no component (C) (Comparative Example 6), the problem of the present application has not been solved.

Claims (6)

  A sizing agent for reinforcing fibers, comprising a component (A) that is an acrylic resin, a rubber component (B), and a component (C) that is a liquid rosin ester resin.   The sizing agent for reinforcing fibers according to claim 1, wherein the weight ratio of the component (C) to the non-volatile content of the sizing agent is 20 to 80% by weight.   The sizing agent for reinforcing fibers according to claim 1 or 2, wherein the non-volatile content of the fiber sizing agent is solid at 20 ° C. The sizing agent for reinforcing fibers according to any one of claims 1 to 3 , wherein the viscosity of the component (C) at 50 ° C and 1 atm is 500,000 mPa · s or less.   A reinforcing fiber strand obtained by adhering the reinforcing fiber sizing agent according to any one of claims 1 to 4 to a raw material reinforcing fiber strand.   A fiber-reinforced composite material comprising a polyolefin resin and the reinforcing fiber strand according to claim 5.