JP7300295B2 - Aramid fiber for resin reinforcement - Google Patents

Description

The present invention relates to aramid fibers, aramid fiber pulp and aramid short fibers for resin reinforcement.

Aramid fibers having high strength, high elastic modulus and excellent heat resistance are used as reinforcing fibers for thermoplastic resins or thermosetting resins.

However, aramid fibers are inferior in adhesiveness to resins compared to other reinforcing fibers such as glass fibers and carbon fibers.

Therefore, a method of applying an epoxy compound and a silane coupling agent to the aramid fiber (see Patent Documents 1 and 2), a method of applying an epoxy compound, an acid-modified polyolefin and a resorcin/formalin/latex (RFL) resin at a specific ratio ( See Patent Document 3) and the like have been proposed.

However, the above method has many problems, such as insufficient adhesion to the resin. Further, although RFL resins are widely used to improve the adhesiveness of aramid fibers in general, practical adhesiveness has not yet been obtained when used for resin reinforcement. From this point of view, in order to further enhance the reinforcing effect of the aramid fiber, there is a demand for the development of an adhesive with improved adhesion to resins.

Japanese Patent Application Laid-Open No. 2001-303456 (Claims, Example 11, etc.) Japanese Patent Application Laid-Open No. 2004-092906 (Claims etc.) JP 2013-001831 A (Claims etc.)

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an aramid fiber that exhibits good adhesion to a resin when used as a resin reinforcing fiber.

The present inventors have made intensive studies to solve the above problems, and found that when used for resin reinforcement by attaching or permeating an epoxy compound, a silane coupling agent and an acid-modified polyolefin to aramid fibers, the resin The inventors have found that aramid fibers with significantly improved adhesive strength to are obtained, and have completed the present invention.

That is, the present invention is as follows.
(1) In the surface or fiber skeleton of the aramid fiber, (A) an epoxy compound, (B) a silane coupling agent, and (C) an acid-modified polyolefin are attached or permeated, and the (A) epoxy compound is , glycerol diglycidyl ether, glycerol triglycidyl ether, sorbitol polyglycidyl ether, and polyglycerol polyglycidyl ether, and the epoxy equivalent of the epoxy compound or epoxy compound mixture is 200 (g /eq) or less for resin reinforcement.
(2) (A) With respect to the number of epoxy functional groups (E) per unit mass of aramid fiber calculated by dividing the adhesion or penetration amount (% by mass) of the epoxy compound by the epoxy equivalent (g / eq) of the epoxy compound, The resin-reinforcing aramid fiber according to ( 1 ), wherein the ratio (S/E) of the number of silanol groups (S) in the (B) silane coupling agent, which is calculated in the same manner, is controlled to 50% or less.
(3) The aramid fiber for resin reinforcement according to (1) or (2) above, wherein the silane coupling agent (B) is an amino group-containing silane coupling agent.
(4) The resin-reinforcing aramid fiber according to any one of (1) to ( 3 ), wherein the acid-modified polyolefin (C) is maleic anhydride-modified polyethylene or maleic anhydride-modified polypropylene.
(5) The resin-reinforcing aramid fiber according to any one of (1) to ( 4 ) above, wherein the aramid fiber is an aramid fiber to which an epoxy compound has previously been attached to the fiber surface.
(6) The resin-reinforcing aramid fiber according to any one of (1) to ( 4 ) above, wherein the aramid fiber is an aramid fiber in which an epoxy compound has been impregnated into the fiber skeleton in advance.
(7) A resin-reinforcing aramid fiber pulp characterized by fibrillating the resin-reinforcing aramid fiber according to any one of (1) to ( 6 ) into a pulp.
(8) A resin-reinforcing aramid short fiber obtained by cutting the resin-reinforcing aramid fiber according to any one of (1) to ( 6 ) into a length of 0.5 mm or more.
(9) A friction material containing the resin-reinforcing aramid fiber according to any one of (1) to ( 6 ) above as a fibrous material.
(10) A sliding member using the friction material described in ( 9 ) above.

According to the present invention, it is possible to provide resin-reinforcing aramid fibers that exhibit good adhesion to thermosetting resins and thermoplastic resins even when used to reinforce these resins.
Further, by fibrillating or cutting the resin-reinforcing aramid fibers of the present invention, resin-reinforcing aramid fiber pulp or resin-reinforcing aramid short fibers having high adhesion to resins and excellent durability can be easily obtained. be able to.

The aramid fiber for resin reinforcement according to the present invention has (A) an epoxy compound, (B) a silane coupling agent, and (C) an acid-modified polyolefin adhered or permeated on the surface or in the fiber skeleton of the aramid fiber. is.

In the present invention, the epoxy compound (A) may be either an aliphatic epoxy compound or an epoxy compound having an aromatic ring, or may be used in combination. family epoxy compounds are preferred.

Aliphatic epoxy compounds can be appropriately selected from known ones and used, but in the present invention, one selected from glycidyl ether compounds of trihydric or higher polyhydric alcohols such as glycerol, sorbitol, and polyglycerol, or A mixture of two or more is preferred.
Specific examples of aliphatic epoxy compounds include glycerol diglycidyl ether, glycerol triglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether and the like.

The epoxy compound having an aromatic ring includes one selected from bisphenol type epoxy resins, or a mixture of two or more of them. Specific examples include bis(4-hydroxyphenyl)methane [bisphenol F], 2,2 -bis(4-hydroxyphenyl)propane [bisphenol A], 2,2-bis(3-methyl-4-hydroxyphenyl)propane [bisphenol C] and the like glycidyl ethers. Among these epoxy compounds, glycidyl etherified products of bisphenol A and bisphenol F, which are liquid at room temperature, are preferred.

Among the above epoxy compounds, glycerol diglycidyl ether, glycerol triglycidyl ether, sorbitol polyglycidyl ether, and polyglycerol polyglycidyl ether are more preferable. The epoxy equivalent weight (mass of epoxy compound containing one equivalent of epoxy group) of these epoxy compounds or epoxy compound mixtures is preferably 200 (g/eq) or less, more preferably 150 (g/eq) or less. If the epoxy equivalent of the epoxy compound exceeds 200 (g/eq), the number of epoxy functional groups that act as reaction points with the silane coupling agent is reduced, resulting in insufficient adhesion. The epoxy equivalent can be measured according to JIS K 7236 (2001).

If necessary, a curing agent may be used together with the epoxy compound. As the curing agent, an amine compound is preferred, and a tertiary amine compound is particularly preferred. Examples thereof include dimethyloctylamine, dimethyldecylamine, dimethyllaurylamine, and long-chain alkylpolyoxyethylene-type tertiary amines obtained by adding ethylene oxide to primary aliphatic amines.

In the present invention, the (B) silane coupling agent can be appropriately selected from known ones and used. , amino group-containing silane coupling agents are preferred.
The amino group-containing silane coupling agent may be appropriately selected from known ones and used. Specific examples thereof include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-( aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N- Phenyl-3-aminopropyltrimethoxysilane and the like can be mentioned, among which 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane are preferred.

In the present invention, the acid-modified polyolefin (C) can be appropriately selected from known ones and used. Maleic acid-modified polyolefins are preferred.

Specific examples of maleic anhydride-modified polyolefins include maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified polybutadiene, maleic anhydride-modified polystyrene, maleic anhydride-modified polymethacrylate, or ethylene, propylene, 1- From linear olefins such as butene, 1-pentene and 1-hexene, branched olefins such as 3-methyl-1-butene, 3-methyl-1-pentene and 4-methyl-1-pentene, butadiene, styrene, etc. A maleic anhydride modified product of a copolymer of two or more selected monomers may be mentioned. Among them, maleic anhydride-modified polyethylene and maleic anhydride-modified polypropylene are preferable.
The weight average molecular weight of the maleic anhydride-modified polyolefin is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000. The Vicat softening point of the maleic anhydride-modified polyolefin may be selected according to the type of resin used for reinforcing the aramid fiber for resin reinforcement, and is generally preferably 80° C. or higher, more preferably 110° C. or higher.

Commercially available maleic anhydride-modified polyolefins may be used, for example, Yumex (manufactured by Sanyo Chemical Industries, Ltd.; maleic anhydride-modified polypropylene), Olevac (manufactured by Arkema; maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene), Kayabrid (manufactured by Kayaku Akzo Co., Ltd.; maleic anhydride-modified polypropylene), and the like.

In the present invention, (A) an epoxy compound, (B) a silane coupling agent, and (C) an acid-modified polyolefin are adhered or permeated onto the surface of the aramid fiber or into the fiber skeleton, thereby improving the adhesion between the aramid fiber and the resin. is greatly improved.
The epoxy compound is preferably attached to or permeated in advance on the surface of the aramid fiber or in the fiber skeleton. When the amino group-containing silane coupling agent and the acid-modified polyolefin are added to the fiber treatment agent, the acid-modified site of the acid-modified polyolefin and the amino group of the amino group-containing silane coupling agent react or form an ionic bond. to form a salt and produce a polyolefin having an alkoxysilyl group. The polyolefin having an alkoxysilyl group thus generated reacts (condensation curing) with the epoxy group or hydroxyl group of the epoxy compound in the aramid fiber to which the epoxy compound has been adhered or permeated in advance, so that the surface of the aramid fiber It is presumed that a polyolefin film is formed.
On the other hand, when only the amino group-containing silane coupling agent is added to the fiber treatment agent, the reaction between the acid-modified site of the acid-modified polyolefin and the amino group of the amino group-containing silane coupling agent does not occur. The alkoxysilyl group of the contained silane coupling agent reacts with the epoxy group or hydroxyl group of the epoxy compound in the aramid fiber, but it is presumed that the adhesion to the resin is weaker than when the polyolefin film is formed.

The amount of the amino group-containing silane coupling agent to be added can be appropriately set in consideration of the effect of improving adhesion, the storage stability of the composition, the physical properties of the resulting film, and the like. is preferably 0.1 to 10 mol, more preferably 0.2 to 5 mol, per 1 mol of the acid-modified site in the acid-modified polyolefin contained in the fiber treatment agent.

The silane coupling agent is calculated by multiplying the epoxy compound amount (% by mass) adhered or permeated to the aramid fiber and the epoxy equivalent weight (g/eq) of the epoxy compound, and the number of epoxy functional groups per unit mass of the aramid fiber (E ) is important. The ratio (S/E) of the number of silanol groups (S) of the silane coupling agent, which is calculated in the same manner as the number of epoxy functional groups (E), is preferably controlled to 50% or less, more preferably 30% or less. preferable. The amount of the silane coupling agent added can be appropriately set in consideration of the balance between the effect of improving the adhesiveness and the storage stability of the composition. A phenomenon occurs in which the adhesive strength of the fibers is lowered.

As described above, there are the following three methods for producing the resin-reinforcing aramid fiber of the present invention.
The first method is to apply (A) an epoxy compound to the aramid fiber and attach the epoxy compound to the surface of the aramid fiber, and (B) the silane cup to the aramid fiber obtained in the step. and a step of applying a fiber treatment agent comprising a ring agent and (C) an acid-modified polyolefin. Furthermore, a step of heat-treating the aramid fibers obtained in the step may be provided.
The second method comprises a step of applying the above-mentioned fiber treatment agent to aramid fibers in which an epoxy compound has been impregnated into the fiber skeleton in advance. Furthermore, a step of heat-treating the aramid fibers obtained in the step may be provided.
A third method comprises a step of applying a fiber treatment agent comprising (A) an epoxy compound, (B) a silane coupling agent, and (C) an acid-modified polyolefin to aramid fibers. Furthermore, a step of heat-treating the aramid fibers obtained in the step may be provided.

Among the above methods, the first method and the second method are preferable because the acid-modified polyolefin is easily immobilized on the surface of the aramid fiber, and as a result, the adhesion between the aramid fiber and the resin is enhanced. The second method is more preferred. The first method and the second method include a dipping step of attaching RFL and a step of heat-treating the attached RFL at 100 to 260 ° C. as a step after the step of applying the fiber treatment agent. good.

In the present invention, the adhesiveness between the aramid fibers and the fiber treatment agent is significantly improved by preliminarily attaching or permeating the epoxy compound to the aramid fibers. Aramid fibers to which an epoxy compound has been attached in advance can be produced by a method of attaching an epoxy compound to aramid fibers by a conventional method. Further, the aramid fiber in which the epoxy compound is preliminarily permeated into the fiber skeleton can be produced by the method described in JP-A-2012-207326. The amount of adhesion or permeation of the epoxy compound is preferably 0.1 to 10.0% by mass, more preferably 0.2 to 2.0% by mass, based on the fiber mass when the moisture content of the aramid fiber is converted to 0%. .

The method of imparting (A) an epoxy compound, (B) a silane coupling agent and (C) an acid-modified polyolefin to the aramid fiber is not particularly limited, and any conventionally known method may be employed. Oiling method, spray oiling method, roller oiling method, guide oiling method using a metering pump, and the like can be mentioned. Usually, it is applied at a room temperature of about 10 to 40° C., but conditions such as temperature may be appropriately adjusted in order to adjust the adhesion amount.

The epoxy compound and fiber treatment agent applied to the aramid fiber of the present invention may further contain a diluent solvent and other additives depending on the desired purpose.
Specific examples of additives include curing catalysts, oils, penetrating agents such as nonionic surfactants, smoothing agents such as silicone compounds, fluorine compounds, and organic surfactants, and resin modifiers such as oxazolines and acid anhydrides. , radical inhibitors, pigments, and the like.

Examples of diluent solvents for the fiber treatment agent include alcohol solvents such as methanol, ethanol and isopropanol; aromatic hydrocarbon solvents such as benzene, toluene and xylene; aliphatic hydrocarbon solvents such as pentane, hexane, heptane and decane. Solvent; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like.

In the present invention, the aramid fiber used for the resin-reinforcing aramid fiber is a fiber having at least one divalent aromatic group which may be usually substituted in the repeating unit of the polymer forming the fiber, The fiber is not particularly limited as long as it has at least one amide bond, and may be referred to as all-aramid fiber or aramid fiber. “Optionally substituted divalent aromatic group” means a divalent aromatic group optionally having one or more substituents which are the same or different.

In the present invention, the aramid fibers include para-aramid fibers, meta-aramid fibers and the like, and para-aramid fibers having excellent tensile strength are particularly preferable.

Such aramid fibers are commercially available, and specific examples thereof include polyparaphenylene terephthalamide fibers (manufactured by DuPont USA, DuPont Toray, trade name "Kevlar" (registered trademark)), copolyparaphenylene -3,4'-Oxydiphenylene terephthalamide fiber (manufactured by Teijin Limited, trade name "Technora" (registered trademark)) and the like.

In the aramid fiber for resin reinforcement of the present invention, the single filament fineness of the fiber is not particularly limited, but is preferably 0.5 to 30 dtex, more preferably 0.5 to 10 dtex, and particularly preferably 1 to 5 dtex.

The resin-reinforcing aramid fiber pulp of the present invention is a highly fibrillated pulp having an average fiber length (mass load average) of about 3 mm or less, and is produced by applying a known method to the resin-reinforcing aramid fiber. can be used, but the machining method is preferred.
In the mechanical processing method, aramid fibers for resin reinforcement are cut into short fibers having a length of 1 to 50 mm, and then the short fibers are crushed, ground, and subjected to mechanical shearing force such as impact or beating. fibrillate.

The resin-reinforcing aramid short fibers of the present invention can be produced by applying a known cutting method such as a guillotine cutter or a rotary cutter to the above resin-reinforcing aramid fibers. The fiber length of the short fibers is preferably 0.5 mm to 100 mm, more preferably 0.5 mm to 50 mm.

The resin-reinforcing aramid fiber of the present invention and the pulp and short fiber obtained by cutting it can be mixed in a suitable ratio with a known thermosetting resin or thermoplastic resin for resin reinforcement. Preferred thermosetting resins include phenol resins, and preferred thermoplastic resins include polyethylene resins, polypropylene resins, nylon resins, polyester resins, polycarbonate resins, and the like.

As a method for mixing and molding with a thermoplastic resin, a known method can be adopted. For example, a short fiber bundle and pellets or powder of a thermoplastic resin are dry-blended, supplied from a feeder, and extruded from an extruder. Strands are extruded and pellets are formed. Then, using the pellets, a fiber-reinforced thermoplastic resin molded article can be obtained by extrusion molding or injection molding.

Pulp and short fibers obtained by cutting the resin-reinforcing aramid fiber of the present invention have acid-modified polyolefin fixed on the fiber surface, and are particularly excellent in adhesiveness to phenolic resins. Therefore, it can be used as a friction material for washers, gears, shafts and bearings, clutch plates, brake plates, etc., as a low-friction material for automobiles, industrial construction machines and machinery.

The friction material of the present invention can be manufactured by the following method. Using the aramid short fibers for resin reinforcement of the present invention as at least a part of a fibrous material, the fibrous material is wet-processed according to a conventional method to produce a paper-like material, and the paper-like material is heated at an appropriate temperature ( For example, it is dried at 80 to 150°C. The content of the short fibers is preferably 50 to 100% by mass, more preferably 70 to 97% by mass, still more preferably 80 to 95% by mass, based on the total amount of the fibrous material.
As fibrous materials other than short fibers, fibers that can be fibrillated such as acrylic fibers, aramid fibers, polyparaphenylenebenzobisoxazole fibers, cellulose fibers, liquid crystal polyester fibers, and wool fibers can be used. Among these fibers, aramid fibers, acrylic fibers, and cellulose fibers are preferred from the viewpoint of heat resistance and high strength, and aramid fibers are more preferred from the viewpoint of abrasion resistance. Among aramid fibers, para-aramid is particularly preferred. Most preferred is aramid pulp obtained by highly fibrillating para-aramid fibers, and as the aramid pulp, the resin-reinforcing aramid fiber pulp of the present invention can be used.

Then, a thermosetting resin such as a phenolic resin as a binding resin is dissolved in an organic solvent such as methanol or acetone and impregnated into the paper-like material formed as described above. Friction modifiers and inorganic materials can be added as appropriate. The impregnation method includes, but is not particularly limited to, a spraying method using a spray or the like, a method of dipping in a bath containing a thermosetting resin, and the like. The impregnation rate is preferably the same amount of the thermosetting resin with respect to the formed paper-like material, but can be set as appropriate.
Thereafter, volatile components are removed from the paper material impregnated with the thermosetting resin or the like at a temperature of 60° C. or less to produce a prepreg.
After that, the prepreg is heat-pressed using a press machine or the like at 130° C. or higher and 190° C. or lower for 1 minute or longer and 15 minutes or shorter at a pressure of 50 kgf/cm ² or higher and 500 kgf/cm ² or lower to obtain a thermosetting resin molded body. Friction material is made by subjecting to high temperature treatment at 130 to 190° C. and hardening. Friction materials can be cut into arbitrary sizes and shapes, molded, and processed as needed to be used as low-friction materials for automobiles, industrial construction machinery and machinery, such as washers, gears, clutch plates, brake plates, and shafts. It can also be used as a friction material such as a bearing and a reinforcing fiber for a sliding member.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to them. The evaluation methods described in Examples are as follows.

(1) Moisture Content of Aramid Fiber Measure the mass of about 5 g of sample (mass before drying). After heat treatment at 300° C. for 20 minutes, the sample is allowed to stand at 25° C. and 65% RH for 5 minutes, and the mass (mass after drying) is measured again.
Moisture content (mass%) = [(mass before drying - mass after drying) / (mass after drying)] x 100

(2) Tensile strength The tensile strength of the prepared material was measured by the method of ASTM D638.

(Example 1)
1 kg of polyparaphenylene terephthalamide (PPTA) (molecular weight: about 20,000) obtained by a known method was dissolved in 4 kg of concentrated sulfuric acid, and was passed through a die having 1,000 holes with a diameter of 0.1 mm at a shear rate of 30, 000 sec ⁻¹ and spun in water at 4° C., then neutralized with a 10 mass % aqueous sodium hydroxide solution at 10° C. for 15 seconds. Then, it was dehydrated and dried at a low temperature of 110° C. to adjust the moisture content to 50% by mass.
The PPTA fibers are impregnated with an oil agent (mixture of diisostearyl adipate/dioleyl adipate/hydrogenated castor oil ethylene oxide adduct/mineral oil) containing glycerol polyglycidyl ether as an epoxy compound by a known oil application method. rice field.
Next, the silane coupling agent and the acid-modified polyolefin in the amounts shown in Table 1 were dissolved in a solvent, applied, and dried at 120° C. to adhere to the PPTA fiber surface.

(Example 2)
A PPTA fiber was obtained in the same manner as in Example 1, except that sorbitol polyglycidyl ether was used in place of glycerol polyglycidyl ether in Example 1, in which the epoxy compound was previously impregnated into the fiber skeleton. Then, in the same manner as in Example 1, a silane coupling agent and acid-modified polyolefin were adhered to the PPTA fiber surface.

(Comparative example 1)
The PPTA fiber obtained in Example 1, in which the epoxy compound was preliminarily permeated into the fiber skeleton, was used.

(Comparative example 2)
To the PPTA fibers obtained in Example 2, in which the epoxy compound had been permeated into the fiber skeleton in advance, only the acid-modified polyolefin in the amount shown in Table 1 was dissolved in a solvent and applied. attached to the fiber surface.

(Comparative Example 3)
In Example 2, the amount of silane coupling agent and acid-modified polyolefin shown in Table 1 was dissolved in a solvent and applied to the PPTA fiber in which the epoxy compound had been impregnated in the fiber skeleton in advance, and dried at room temperature. , was attached to the PPTA fiber surface.

The PPTA fibers produced in each of the above examples and comparative examples were cut with a roving cutter into 3 mm fiber lengths to prepare short fibers, which were subjected to friction material evaluation tests.

(Test Example 1: Friction material evaluation)
A dry weight of 200 g of cut water-containing PPTA fiber composite short fibers was dispersed in 60 kg of deionized water and fibrillated at 3,000 rpm using a single disc refiner to obtain PPTA fiber composite pulp. The freeness of the pulp measured by the method of JIS P8121-2 was 770 mL.

25 g of the dry weight of the water-containing PPTA fiber composite pulp thus obtained was dispersed in 4 liters of water at 3,000 rpm using a pulp disintegrator, and then subjected to a #80 mesh wire mesh using a 25 cm square square sheet machine. was used to make paper according to a conventional method, and then dried to obtain para-aramid paper of 25 cm square and unit weight of 200 g/m ² .

Next, the obtained para-aramid paper was immersed in a resin solution prepared by diluting a resol-type phenolic resin prepolymer with an equal amount of methanol to impregnate the paper with the resin solution. A prepreg was obtained by drying for a minute. The prepreg was further preformed at 140° C. for 2 minutes under a pressure of 10 MPa, and then heat-cured at 220° C. for 8 minutes to prepare a 0.6 mm, 12.5 cm square aramid pulp-reinforced phenolic resin plate. .

A strip of 120 mm×10 mm was cut out from the plate of 0.6 mm thus obtained to obtain a tensile test piece with a chuck-to-chuck distance of 60 mm.

The above results are also shown in Table 1.

In addition, each component in Table 1 is as follows.
・Amino group-containing silane coupling agent; 3-aminopropyltriethoxysilane ・Acid-modified polyolefin; maleic anhydride-modified polyethylene

As shown in Table 1, the PPTA fibers of Examples 1 and 2, to which the amino group-containing silane coupling agent and the acid-modified polyolefin were added, have excellent adhesive strength between the resin and the fiber, resulting in high tensile strength. I understand.
On the other hand, the PPTA fiber of Comparative Example 1 to which the amino group-containing silane coupling agent and the acid-modified polyolefin were not imparted and the PPTA fiber of Comparative Example 2 to which the silane coupling agent was not imparted had insufficient adhesion to the resin. , it can be seen that the tensile strength is insufficient. In addition, it can be seen that the PPTA fiber of Comparative Example 3, which has excess silanol groups, in which the ratio of the number of silanol groups to the number of epoxy functional groups exceeds 50%, has a reduced adhesiveness between the fiber and the resin.

The resin-reinforcing aramid fiber of the present invention is useful as a reinforcing material for various resins.

Claims (10)

(A) an epoxy compound, (B) a silane coupling agent, and (C) an acid-modified polyolefin adhere to or permeate the surface or fiber skeleton of the aramid fiber, and the (A) epoxy compound is glycerol di- one or more selected from glycidyl ether, glycerol triglycidyl ether, sorbitol polyglycidyl ether, and polyglycerol polyglycidyl ether, and the epoxy compound or epoxy compound mixture has an epoxy equivalent of 200 (g/eq); An aramid fiber for resin reinforcement characterized by the following . (A) The number of epoxy functional groups (E) per unit mass of aramid fiber calculated by dividing the adhesion or penetration amount (% by mass) of the epoxy compound by the epoxy equivalent (g / eq) of the epoxy compound, in the same manner The aramid fiber for resin reinforcement according to claim 1 , wherein the calculated ratio (S/E) of the number of silanol groups (S) possessed by (B) the silane coupling agent is controlled to 50% or less. (B) The aramid fiber for resin reinforcement according to claim 1 or 2 , wherein the silane coupling agent is an amino group-containing silane coupling agent. (C) The aramid fiber for resin reinforcement according to any one of claims 1 to 3 , wherein the acid-modified polyolefin is maleic anhydride-modified polyethylene or maleic anhydride-modified polypropylene. The resin-reinforcing aramid fiber according to any one of claims 1 to 4 , wherein the aramid fiber is an aramid fiber to which an epoxy compound has previously been attached to the fiber surface. The resin-reinforcing aramid fiber according to any one of claims 1 to 4, wherein the aramid fiber is an aramid fiber in which an epoxy compound has been impregnated into the fiber skeleton in advance. A resin-reinforcing aramid fiber pulp characterized by fibrillating the resin-reinforcing aramid fiber according to any one of claims 1 to 6 into a pulp. A resin-reinforcing aramid short fiber obtained by cutting the resin-reinforcing aramid fiber according to any one of claims 1 to 6 to a length of 0.5 mm or more. A friction material comprising the resin-reinforcing aramid fiber according to any one of claims 1 to 6 as a fibrous material. A sliding member using the friction material according to claim 9 .