CN110699960A - A sizing agent for thermoplastic resin reinforced fibers - Google Patents

Abstract

The invention discloses a sizing agent for thermoplastic resin reinforced fibers. The sizing agent for reinforced fibers is composed of acid-modified polyolefin, vinyl ester compound and water. The weight ratio of acid-modified polyolefin resin and vinyl ester compound is: 1:9‑1:1. Wherein the acid-modified polyolefin is composed of at least one of polypropylene, ethylene-propylene copolymer, propylene-butene copolymer, ethylene-propylene-butene copolymer, and 0.1~20wt% of unsaturated carboxylic acid or its Obtained by graft polymerization of acid anhydrides. The fibers treated with the sizing agent have good fiber opening and affinity with the thermoplastic matrix resin, and the sizing agent also has excellent heat resistance and can withstand the high temperature molding process of the thermoplastic resin.

Description

A sizing agent for thermoplastic resin reinforced fibers

technical field

The present invention relates to the technical field of fiber augmentation, in particular to a sizing agent for thermoplastic resin reinforced fibers.

Background technique

Fiber reinforced resin composites are widely used in automobile manufacturing, aerospace, sports entertainment, general industry and other fields. The reinforcing fibers used in composite materials include inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, and organic fibers such as aramid fibers, polyamide fibers, and polyethylene fibers. These synthetic fibers can be prepared into intermediate materials such as unidirectional prepregs in the form of continuous long fibers by the melt impregnation method, or the fibers can be processed into fabrics or cut into chopped fibers, and then undergo various compounding and molding processes. Prepared into moldings and parts.

In the past, in the field of advanced composite materials, thermosetting resins such as epoxy resins were mostly used as matrix materials, mainly because the mechanical properties of thermosetting resins after curing were better. However, in recent years, from the viewpoints of molding efficiency, convenient recycling, and convenience for large-scale industrial applications, so-called polyolefin resins, polyamide resins, polycarbonate resins, polyacetal resins, ABS resins, and polyurethane resins have been used. The thermoplastic resin composite material of thermoplastic resin as the base material is rapidly expanding in its application range and scale.

Thermoplastic resin composite materials are generally formed by cutting the reinforcing fibers into short fibers with a length of 1 to 15 mm, and then kneading them with the resin by extrusion or other methods. When kneading chopped fibers and thermoplastic resin for granulation, the openness of chopped fibers is very important. If they cannot be well dispersed, the supply of fibers will be unstable, and the dispersion in the resin will be uneven, resulting in composite materials. performance is poor.

In addition, in recent years, in order to better exert the mechanical properties such as the tensile strength of reinforcing fibers, a molding method similar to thermosetting resin composite materials has also been developed for thermoplastic resins, that is, fibers are unidirectionally arranged, or fiber fabrics are used. , impregnated in thermoplastic resin to obtain so-called thermoplastic resin prepreg, which is then processed into parts by further molding. In this case, during the preparation and molding of the prepreg, whether the molten resin can quickly enter the fiber bundle and be uniformly distributed in the fiber gap is very critical for shortening the molding time and improving the physical properties of the composite material.

In order to improve the bundling of the reinforcing fibers and the affinity between the fibers and the matrix resin, the fibers are usually sizing with a sizing agent. The traditional sizing agent mainly uses epoxy resin as an active ingredient, which can endow the fibers with better clustering and good surface affinity with thermosetting resin substrates such as epoxy resin. However, it is difficult to meet the use requirements of thermoplastic resin substrates. Especially when polyolefin resin is used as the resin substrate, since the molding temperature is much higher than the curing temperature of general thermosetting resins, the heat resistance of the sizing agent is also very high. If the heat resistance of the sizing agent is insufficient, in the molding process Decomposition will occur, affecting the combination of fibers and resins, resulting in a decline in composite performance and grade.

In addition, in order to improve the film-forming properties of general sizing agents, their main components are mostly solid at room temperature. Although they are used for chopped fibers, their excellent bundling properties are beneficial to processing, but when they are used in the form of long fibers, they will There is a problem of poor resin impregnation, that is, the resin cannot quickly enter the inside of the fiber bundle. Moreover, in the manufacturing process of the prepreg, the fibers are usually opened first, and the traditional sizing agent has poor fiber opening. Therefore, in the field of thermoplastic resin composite materials, there is a need for a sizing agent that can have good affinity with resins, at the same time enable fibers to have good fiber openability, and itself has good heat resistance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a fiber sizing agent with excellent heat resistance, good fiber openability for fiber bundles, and good affinity with thermoplastic resin matrix.

In order to achieve the above object, the present invention adopts the following technical solutions:

A sizing agent for thermoplastic resin reinforcing fibers, consisting of acid-modified polyolefin resin, vinyl ester compound and water.

The sizing agent for reinforcing fibers in the present invention must contain the aforementioned acid-modified polyolefin, vinyl ester compound and water. In this way, the sizing agent can have good heat resistance, and the decomposition of the sizing agent can be suppressed when it is compounded with the thermoplastic resin at high temperature. Sex has also improved significantly. Especially for polyolefin resin, its bonding effect is the best.

The weight ratio of acid-modified polyolefin resin and vinyl ester compound in the sizing agent (acid-modified polyolefin: vinyl ester compound) should be 1:9- Between 1:1, preferably 1:4-9:11, more preferably between 1:3-1:2.

In the sizing agent of the present invention, the acid-modified polyolefin and the vinyl ester compound are dispersed in water to form an emulsion, and the average particle size thereof should be between 1 and 5000 nm, preferably 10 to 1000 nm. If the particle size is less than 1 nm, the acid-modified polyolefin resin particles can easily penetrate the fiber bundle, and it is difficult to achieve a certain amount of adhesion on the fiber. If the particle size exceeds 5000 nm, the adhesion on the fiber is not uniform, and the stability of the emulsion itself changes. Poor, it is completely delaminated within a few days, which is not conducive to actual preservation and use.

The average particle size in the above emulsion was measured using a laser particle size analyzer.

In addition to the above-mentioned essential components, various components such as surfactants, smoothing agents, antioxidants, flame retardants, antibacterial agents, and defoaming agents can also be used in the sizing agent of the present invention. Especially when the acid-modified polyolefin resin and vinyl ester compound used are poorly soluble in water, a surfactant as an emulsifier is very important to form a stable aqueous emulsion system. The weight ratio of the surfactant in the non-volatile components of the sizing agent should be between 0.1% and 30%, preferably between 5% and 20%, in consideration of the emulsifying effect and heat resistance.

In the present invention, the concentration of the nonvolatile components of the sizing agent, that is, the solid content, is not particularly limited, but, considering the stability of the emulsion, the viscosity during operation, and the transportation cost, it should be between 10 and 60 wt %. , preferably 15-60%, more preferably 20-50%.

In the sizing agent of the present invention, the mass reduction rate of its nonvolatile components at 400° C. should not exceed 15%, preferably less than 10%. If it exceeds 15%, the sizing agent will decompose obviously during the high temperature molding process, and the resulting decomposition products will affect the bonding strength of the fiber and the resin.

In the sizing agent water emulsion, as mentioned above, considering the safety to the human body, the environmental friendliness, and the stability of the emulsion itself, try not to contain other solvents other than water. Even if it is contained, its content should not exceed 10% by weight relative to the sizing agent, preferably 5%, and most preferably not more than 1%.

The manufacturing method of the sizing agent in the present invention is not particularly limited, and various well-known methods can be adopted, such as adding each main component to warm water with stirring to disperse and emulsification, or emulsification and mixing of each component separately, or mixing the main components. Then, heating to above the softening point, then using a homogenizer, etc. to apply shearing force, slowly adding water for diversion and emulsification, etc.

Preferably, in the above sizing agent: the acid-modified polyolefin resin is made of at least one of polypropylene, ethylene-propylene copolymer, propylene-butene copolymer, and ethylene-propylene-butene copolymer , obtained by graft polymerization with unsaturated carboxylic acid or its acid anhydride in a mass ratio in the range of 100:1 to 5:1.

In the main chain of the acid-modified polyolefin, the propylene segment should account for more than 50-98 mol%. If the proportion of propylene segment is lower than 50%, the affinity of the fiber with thermoplastic resin will be poor. If it is higher than 98%, the fiber will become stiff after treatment and lose its flexibility. If the main chain of the acid-modified polyolefin is an ethylene-propylene-butene copolymer structure, the proportion of butene units therein should be less than 10 mol%.

The number of carbon atoms of the unsaturated carboxylic acid used for graft copolymerization in acid-modified polyolefin should be between 3 and 8. The unsaturated carboxylic acid here can be an unsaturated monobasic acid, an unsaturated diacid acid, or derivatives such as their esters. Specifically, maleic acid, maleic anhydride, fumaric acid, antacid, acrylic acid, methacrylic acid, methacrylate and the like. Among them, maleic acid, acrylic acid, methacrylic acid and methacrylic acid are preferred. The proportion of unsaturated carboxylic acid units in the whole molecule should be between 0.1 and 20 wt %, preferably between 1 and 15 wt %, and more preferably between 2 and 10 wt %. If the content is less than 0.1%, the affinity between the treated fiber and the resin is poor, and it is very difficult to exceed 20% under normal reaction conditions.

To graft the unsaturated carboxylic acid compound on the main chain of the polyolefin, a known method such as solution polymerization, bulk polymerization and the like can be used.

The unsaturated carboxylic acid used in the acid-modified polyolefin resin can be fully or partially neutralized, and the basic substance used for neutralization can be inorganic bases such as sodium hydroxide, potassium hydroxide, aluminum hydroxide, etc., or Ammonia, methylamine, dimethylamine, trimethylamine, triethylamine, tetramethylammonium hydroxide and other amine substances.

The weight average molecular weight of the acid-modified polyolefin resin should be between 3,000 and 200,000, preferably between 5,000 and 200,000, and more preferably between 10,000 and 150,000. If the weight-average molecular weight is less than 3,000, the fibers will have insufficient bundles after treatment, which will affect the workability of the subsequent processing. If the weight-average molecular weight exceeds 2,000,000, it will be very difficult to disperse in water, and it will not be possible to prepare a water-based sizing agent. The diameter is also very large, and the emulsion is very unstable and cannot be stored and used for a long time.

A reinforcing fiber bundle is prepared by treating the reinforcing fibers with the above-mentioned sizing agent.

The reinforcing fiber bundle in the present invention refers to a fiber bundle that has been treated with the above-mentioned sizing agent and is used to reinforce a thermoplastic resin. It has excellent fiber opening and affinity with resin. At the same time, because the sizing agent has good heat resistance, it will not decompose in the process of high temperature compounding.

The adhesion amount of the sizing agent on the fiber, that is, the amount of sizing can be flexibly selected according to the actual situation, usually between 0.5 and 5%. If it is in the form of chopped fibers, the sizing amount should be appropriately increased, which can be between 1 and 10%. If the sizing amount is too small, the main objects of the present invention, such as heat resistance of the fiber, resin impregnation, and resin affinity, cannot be achieved. The resin impregnation property also deteriorates.

The manufacturing method of the synthetic fiber bundle in the present invention mainly includes a dilution process of diluting the above-mentioned sizing agent to 0.5-10%, and using the diluted sizing agent treatment solution to sizing the raw fiber bundle to reach 0.5-5% % of the sizing amount of the sizing process.

During the dilution process, the concentration of the sizing agent treatment solution should be between 1 and 10%, preferably between 2 and 5%. For the sizing process, well-known methods such as roller dipping method and spray method can be specifically used. From the comprehensive consideration of uniform adhesion and cost, the dipping method is preferred.

The fiber bundle after sizing should be dried, and the drying method is not limited, such as hot roller drying, hot air drying, etc.

Synthetic fibers suitable for the sizing agent of the present invention include inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, as well as aramid fibers, polyethylene fibers, polyethylene terephthalate (PET) fibers, polybutylene terephthalate Various organic fibers such as diester (PBT) fibers, polyethylene naphthalate (PEN) fibers, polyacetal fibers, PBO fibers, polyarylate fibers, and polyketone fibers. Considering the physical properties of the obtained composite material, carbon fibers, aramid fibers, polyethylene fibers, polyethylene terephthalate (PET) fibers, polybutylene terephthalate (PBT) fibers, Polyacetal fiber, PBO fiber, polyarylate and polyketone fiber are preferred, especially carbon fiber.

Preferably, in the above-mentioned reinforcing fiber bundle: the reinforcing fiber is carbon fiber, aramid fiber, polyethylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyacetal fiber, PBO fiber or polyketone fiber.

A fiber-reinforced resin-based composite material is formed by compounding the above-mentioned reinforcing fiber bundles and thermoplastic resins. The fiber-reinforced composite material in the present invention is obtained by using a thermoplastic resin as a matrix material to be combined with the aforementioned reinforcing fibers. Due to the use of the aforementioned sizing agent, the reinforcing fibers have good affinity with the resin matrix, so that a composite material with excellent performance can be obtained.

As long as the thermoplastic resin base material used here is a thermoplastic resin, it may be used alone or in combination of two or more. Specifically, polyolefin resin, polyamide resin, polycarbonate resin, polyester resin, ABS resin, polymethyl methacrylate resin, polyurethane resin, polyether ketone resin, etc. are used. Among them, polyolefin resin is a polymer material obtained by polymerizing olefin as a monomer, which can be a monomer or a copolymer.

The thermoplastic resin substrate described above may be appropriately modified in order to improve the affinity with fibers or its own physical properties.

The manufacturing method of the composite material is not limited, such as extrusion molding using chopped fiber and resin after mixing, molding using UD unidirectional board or fabric prepreg, and winding molding and other molding methods.

The content of fibers in the composite material is not specifically limited, and should be appropriately selected and adjusted according to the shape and type of the fibers and the type of the thermoplastic resin substrate. From the viewpoint of reinforcing effect, the mass content of fibers should be between 5 and 70%, preferably between 20 and 60%.

Preferably, in the above sizing agent: the vinyl ester compound refers to a compound containing both vinyl and ester active groups at the molecular end, and the usual vinyl ester resin is acrylic acid or methacrylic acid, etc. It is obtained by reacting unsaturated carboxylic acid with epoxy resin. In terms of its molecular structure, it may be an aromatic compound or an aliphatic compound.

There are many kinds of vinyl ester compounds. From the viewpoint of heat resistance, the preferred vinyl ester compounds are bisphenol A acrylate, bisphenol A methacrylate, ethoxylated bisphenol A acrylate, and ethoxylated bisphenol A methacrylate. , acrylic acid adduct of bisphenol A diglycidyl ether, methacrylic acid adduct of bisphenol A diglycidyl ether, acrylic acid adduct of ethoxylated bisphenol A diglycidyl ether or ethoxylated bisphenol A diglycidyl ether Methacrylic acid adduct of glycidyl ether.

Compared with the prior art, the present invention has the following beneficial effects:

The sizing agent for fibers in the present invention has excellent heat resistance, excellent fiber opening performance of the treated fiber bundles, and good affinity with thermoplastic resins. Fiber-reinforced thermoplastic resin composite materials with excellent physical properties can be obtained.

Detailed ways

Hereinafter, the present invention will be specifically described by way of examples. The percentages in the examples are all mass percentages, or mass fractions. In addition, each measurement evaluation method is as follows.

<Affinity>

Using the composite interface property evaluation device HM410 produced by Japan Toei Sangyo Co., Ltd., the affinity of fibers and resins was rated.

Since all the fibers used in the examples are carbon fibers, carbon fiber monofilaments were fixed on the device, and molten polypropylene resin J-900GP was dropped onto the fibers from above, and cooled to room temperature to obtain a test sample. The sample was fixed in a jig and pulled out at a speed of 0.06 mm/min, and the maximum tensile force F was measured. Then, the interfacial shear strength τ was calculated according to the following formula, which was used as an evaluation index for the affinity of carbon fiber and polypropylene resin.

Interfacial shear strength τ(MPa)=F/πdl

Among them, F is the maximum pull-out load, d is the diameter of the carbon fiber monofilament, and l is the diameter of the droplet in the pull-out direction.

<fiber opening>

A carbon fiber with a fineness of 800 tex, a number of filaments of 12,000, and a sizing amount of 1.0% was taken as a sample. Measured using a fabric testing machine. The smaller the measured value, the better the openability.

Evaluation Standards:

A: Below 50g, the carbon fiber tow is soft and the fiber opening is very good

B: 50～60g, the carbon fiber tow is soft and has good fiber opening

C: 60g or more, the tow is hard and the fiber opening is poor

mass reduction rate

Thoroughly dry the sizing agent at 105°C to constant weight, use a thermal analyzer to heat up to 500°C at a heating rate of 20°C/min in an air atmosphere, and obtain its mass reduction rate at 300°C according to its thermogravimetric curve. .

<Emulsion particle size>

The particle size of the emulsion was measured using a laser particle sizer.

<Production of acid-modified polyolefin resin emulsions A1 to A4>

(A1-1～A1-3)

100 g of polypropylene resin and 400 g of toluene were added to the flask, and the flask was heated and dissolved while stirring. Keeping the temperature above the melting point of the polypropylene resin, adding anhydrous maleic acid and methyl methacrylate to carry out graft polymerization of polypropylene, anhydrous maleic acid and methyl methacrylate to obtain acid-modified polypropylene resin.

245 parts by mass of the obtained acid-modified polypropylene resin, 20 parts of aliphatic polyoxyethylene ether, 15 parts of potassium hydroxide, and 20 parts of morpholine were stirred under nitrogen protection, heated to 170-180 ° C, and then slowly added 700 parts of water, maintaining the temperature at 170-180° C. for two hours to completely and uniformly dissolve the acid-modified polypropylene resin. Cool to normal temperature, add water to obtain acid-modified polypropylene resin emulsions A1-1 to A1-3 with a concentration of 30%.

The particle size was measured using a laser particle size analyzer and found to be 30 nm. Placed at 50°C for 1 month, no flocculation, no stratification, no oil drift, and has good stability. The specific characteristics of the three modified resins are as follows:

A1-1: polypropylene main chain, graft modification amount of 5%, MW=4500

A1-2: polypropylene main chain, graft modification amount of 5%, MW=28000

A1-3: polypropylene main chain, graft modification amount of 15%, MW=37000

(A2-1～A2-3)

100 g of ethylene-propylene copolymer resin and 400 g of toluene were put into the flask, and the flask was heated and dissolved while stirring. The temperature is kept above the melting point of the resin, anhydrous maleic acid and methyl methacrylate are added, and the ethylene-propylene copolymer resin, anhydrous maleic acid and methyl methacrylate are subjected to graft polymerization to obtain an acid-modified polymer. Olefin resin.

250 parts by mass of the obtained acid-modified polyolefin resin, 15 parts of aliphatic polyoxyethylene ether, 15 parts of potassium hydroxide, and 20 parts of morpholine were stirred under nitrogen protection, heated to 170-180 ° C, and then slowly added 700 parts of water, maintained at a temperature of 170 to 180° C. for two hours, so that the acid-modified polyolefin resin was completely and uniformly dissolved. Cool to normal temperature, add water to obtain acid-modified polyolefin resin emulsions A2-1 to A2-3 with a concentration of 30%.

The particle size was measured using a laser particle sizer and found to be 20 nm. Placed at 50°C for 1 month, no flocculation, no stratification, no oil drift, and has good stability. The specific characteristics of the three acid-modified polyolefin resins are as follows:

A2-1: Main chain of ethylene-propylene copolymer, graft modification amount of 3%, MW=58000

A2-2: Main chain of ethylene-propylene copolymer, graft modification amount of 5%, MW=63000

A2-3: Main chain of ethylene-propylene copolymer, graft modification amount of 10%, MW=65000

(A3-1～A3-3)

100 g of propylene-butene copolymer resin and 400 g of toluene were put into a high-pressure flask, and the mixture was heated and dissolved while stirring. Keeping the temperature above the melting point of the resin, adding anhydrous maleic acid and methyl methacrylate to carry out graft polymerization of the resin, anhydrous maleic acid and methyl methacrylate to obtain an acid-modified polyolefin resin.

245 parts by mass of the obtained acid-modified polyolefin resin, 15 parts of aliphatic polyoxyethylene ether, 15 parts of potassium hydroxide, and 25 parts of morpholine were stirred under nitrogen protection, heated to 170-180 ° C, and then slowly added 700 parts of water, maintained at a temperature of 170 to 180° C. for two hours, so that the acid-modified polyolefin resin was completely and uniformly dissolved. Cool to normal temperature, add water to obtain acid-modified polyolefin resin emulsions A3-1 to A3-3 with a concentration of 30%.

The particle size was measured using a laser particle sizer and found to be 20 nm. Placed at 50°C for 1 month, no flocculation, no stratification, no oil drift, and has good stability. The specific characteristics of the three acid-modified polyolefin resins are as follows:

A3-1: Main chain of propylene-butene copolymer, graft modification amount of 5%, MW=35000

A3-2: Main chain of propylene-butene copolymer, graft modification amount of 10%, MW=60000

A3-3: Main chain of propylene-butene copolymer, graft modification amount of 20%, MW=71000

(A4-1～A4-3)

100 g of ethylene-propylene-butene copolymer resin and 400 g of toluene were put into the flask, and the flask was heated and dissolved while stirring. Keep the temperature above the melting point of the resin, add anhydrous maleic acid and methyl methacrylate, and make the ethylene-propylene-butene copolymer resin, anhydrous maleic acid and methyl methacrylate to carry out graft polymerization to obtain acid. Modified polyolefin resin.

250 parts by mass of the obtained acid-modified polyolefin resin, 10 parts of aliphatic polyoxyethylene ether, 15 parts of potassium hydroxide, and 25 parts of morpholine were stirred under nitrogen protection, heated to 170-180 ° C, and then slowly added 700 parts of water, maintained at a temperature of 170 to 180° C. for two hours, so that the acid-modified polyolefin resin was completely and uniformly dissolved. Cool to normal temperature, add water to obtain acid-modified polyolefin resin emulsions A4-1 to A4-3 with a concentration of 30%.

The particle size was measured using a laser particle sizer and found to be 20 nm. Placed at 50°C for 1 month, no flocculation, no stratification, no oil drift, and has good stability. The specific characteristics of the three acid-modified polyolefin resins are as follows:

A2-1: Main chain of ethylene-propylene-butene copolymer, graft modification amount of 5%, MW=42000

A2-2: Main chain of ethylene-propylene-butene copolymer, graft modification amount of 10%, MW=62000

A2-3: Main chain of ethylene-propylene-butene copolymer, graft modification amount of 15%, MW=68000

<Production of vinyl ester compound emulsions B1 to B4>

(B1)

The acrylic acid adduct of bisphenol A diglycidyl ether/castor oil polyoxyethylene (150) ether is added to the emulsifying device in a mass ratio of 80/20, and water is slowly added while stirring to turn to emulsification to obtain a uniform The solids content of emulsion B1.B1 was 40%.

The particle size of the emulsion B1 was measured, the average particle size was 190 nm, and it was placed at a temperature of 50° C. for 1 month without flocculation, stratification, and oil drift, and had good stability.

(B2)

(4) ethoxylated bisphenol A acrylate/castor oil polyoxyethylene (150) ether is added to the emulsifying device in a mass ratio of 80/20, slowly adding water while stirring, and turning to emulsification to obtain a uniform emulsion B2 .B2 has a solids content of 40%.

The particle size of the emulsion B2 was measured, and the average particle size was 250 nm. It was placed at a temperature of 50° C. for 1 month without flocculation, stratification, and oil drift, and had good stability.

(B3)

Trimethylolpropane triacrylate/ethylene-propylene block polyether (MW15000, the ratio of propoxy to ethoxy is 20/80)/ethylene-propylene block polyether (MW2000, propoxy and ethoxy The base ratio is 60/40) is added to the emulsification device at a mass ratio of 70/15/15, and water is slowly added while stirring to perform diversion and emulsification to obtain a uniform emulsion B4. The solid content of B4 is 40%.

The particle size of the emulsion B1 was measured, the average particle size was 210 nm, and it was placed at a temperature of 50° C. for one month, without flocculation, stratification, and oil drift, and had good stability.

<Examples 1 to 21, Comparative Examples 1 to 4>

The acid-modified polyolefin emulsion and the vinyl ester compound emulsion produced above were mixed and stirred according to the proportions shown in Tables 1 to 3, and diluted with water to a sizing agent with a solid content of 10%. The obtained sizing agent was measured for its fiber openability and mass reduction rate by the above-mentioned method.

The unsized carbon fibers (fineness of 800 tex, number of filaments of 12K) were sizing by the dipping method, and after drying, carbon fiber bundles with a sizing amount of about 5% were obtained. The affinity with resin was evaluated.

All results are shown in Tables 1-3.

Table 1

Table 2

table 3

Claims (8)

1. A sizing agent for thermoplastic resin reinforcing fibers, characterized in that: comprising an acid-modified polyolefin resin, a vinyl ester compound and water.

2. The sizing agent according to claim 1, characterized in that: the weight ratio of the acid-modified polyolefin resin to the vinyl ester compound is 1:9 to 1: 1.

3. The sizing agent according to claim 1, wherein the acid-modified polyolefin resin is obtained by graft-polymerizing at least one of polypropylene, an ethylene-propylene copolymer, a propylene-butene copolymer and an ethylene-propylene-butene copolymer with an unsaturated carboxylic acid or an anhydride thereof at a mass ratio of 100:1 ~ 5: 1.

4. The sizing agent according to claim 1, characterized in that: the vinyl ester compound is bisphenol A acrylate, bisphenol A methacrylate, ethoxylated bisphenol A acrylate, ethoxylated bisphenol A methacrylate, acrylic acid adduct of bisphenol A diglycidyl ether, methacrylic acid adduct of bisphenol A diglycidyl ether, acrylic acid adduct of ethoxylated bisphenol A diglycidyl ether, or methacrylic acid adduct of ethoxylated bisphenol A diglycidyl ether.

5. A reinforcing fiber bundle characterized by being obtained by treating reinforcing fibers with the sizing agent according to claim 1.

6. The reinforcing fiber bundle of claim 5, wherein: the reinforced fiber is carbon fiber, aramid fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyacetal fiber, PBO fiber or polyketone fiber.

7. A fiber-reinforced resin-based composite material characterized by being formed by compounding the reinforcing fiber bundles according to claim 4 with a thermoplastic resin.

8. The fiber reinforced resin based composite material according to claim 7, wherein: the thermoplastic resin is polyolefin resin, polyamide resin, polycarbonate resin, polyester resin, ABS resin, polymethyl methacrylate resin, polyurethane resin or polyether ketone resin.