JP2009035661A - Phenol resin composition for friction material, its manufacturing method, and friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin composition for a friction material with sufficient heat-resistance excellent in a low abrasion property without requiring gas removal at molding and without generating a void and a crack on a molded article, and to provide its manufacturing method and a friction material. <P>SOLUTION: The phenol resin composition for the friction material is formed by uniformly melting and mixing a novolak type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin and a curing catalyst. Ratios of the respective components are preferably 30-90 wt.% of the novolak type phenol resin, 2-50 wt.% of the resol type phenol resin, 5-50 wt.% of the alkyl-substituted aromatic hydrocarbon resin, 2-50 wt.% of the epoxy resin, and 0.1-10 wt.% of the curing catalyst. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phenol resin composition for a friction material, a method for producing the same, and a friction material.

  Conventional phenol resin compositions for friction materials are generally based on novolak type phenol resins, using hexamethylenetetramine as a curing agent, or using resole type phenol resins alone or in combination with novolac type phenol resins. Met. When such a phenol resin composition is used, ammonia gas is generated by decomposition of condensed water and hexamethylenetetramine during molding, that is, during the curing reaction of the resin. Water vapor and ammonia gas resulting from these condensed waters inhibit the uniform curing of the resin and cause voids, cracks, etc. in the molded product, resulting in poor appearance of the molded product, reduced mechanical strength, etc. There was a problem. For this reason, it is necessary to perform a degassing operation at the time of molding, resulting in a problem that the process is complicated and takes a long time, and the efficiency and workability are poor.

In order to solve such problems, a phenolic resin composition was invented that does not substantially generate a gas caused by a curing reaction during molding by uniformly melting and mixing a novolac type phenolic resin, an epoxy resin, and a curing catalyst. Some are put to practical use (see, for example, Patent Document 1). However, such a phenol resin composition may have insufficient heat resistance in applications where it is exposed to a large thermal shock.
Japanese Patent Laid-Open No. 2001-213941

  The present invention does not require degassing at the time of molding, does not cause voids and cracks in the molded product, has excellent low wear properties, and has good heat resistance, a friction resin phenol resin composition, a method for producing the same, and friction The material is provided.

Such an object is achieved by the following present invention [1] to [5].
[1] A phenol resin composition for a friction material, characterized by uniformly melting and mixing a novolac type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin and a curing catalyst.
[2] The proportion of each component is 30 to 90% by weight of novolak type phenol resin, 2 to 50% by weight of resol type phenol resin, 5 to 50% by weight of alkyl-substituted aromatic hydrocarbon resin, 2 to 50% by weight of epoxy resin and curing. The phenol resin composition for a friction material according to item [1], wherein the catalyst content is 0.1 to 10% by weight.
[3] The phenol resin composition for a friction material according to [1] or [2], wherein the free phenol in the composition is less than 1% by weight.
[4] A production method for producing the phenol resin composition for a friction material according to any one of items [1] to [3], comprising at least a novolac-type phenol resin, an epoxy resin and / or a curing catalyst. A method for producing a phenol resin composition for a friction material, characterized by melt-mixing with a pressure kneader.
[5] A friction material comprising the phenol resin composition for a friction material according to any one of items [1] to [3].

  The composition of the present invention does not need to be degassed during molding, and has excellent workability. Furthermore, by using the composition of the present invention as a friction material, it is possible to obtain a friction material excellent in low wear and heat resistance. Furthermore, by applying the production method of the present invention, the composition can be uniformly dispersed with high accuracy, and the above-described effects can be effectively exhibited when used in a friction material.

  Hereinafter, the phenol resin composition for a friction material of the present invention and a method for producing the same will be described. The phenol resin composition for friction material of the present invention (hereinafter referred to as “composition”) contains a novolac type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin, and a curing catalyst. Features. The free phenol in the composition of the present invention is preferably less than 1% by weight. In addition, the method for producing the phenol resin composition for a friction material according to the present invention includes at least the novolak of raw materials including a novolac type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin, and a curing catalyst. A type phenol resin and the epoxy resin and / or the curing agent are melt-kneaded using a pressure-type kneader. First, the composition of the present invention will be described.

  The novolak-type phenol resin used in the composition of the present invention usually comprises phenols and aldehydes in the presence of an acidic catalyst such as oxalic acid, hydrochloric acid, sulfuric acid, toluenesulfonic acid, etc., with respect to the phenols (P). The reaction molar ratio (F / P) of (F) is 0.5 to 0.9.

Although it does not specifically limit as phenols used here, For example, phenol, such as phenol, orthocresol, metacresol, paracresol, xylenol, para tertiary butylphenol, paraoctylphenol, paraphenylphenol, bisphenol A, bisphenol F, resorcinol Usually, phenol and cresol are often used. Similarly, although not particularly limited as aldehydes, for example, aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, or a mixture thereof, substances that generate these aldehydes, or these aldehydes Although a similar solution can be used, usually formaldehyde is often used. The form of the novolac-type phenol resin thus obtained is not particularly limited, and any form such as liquid, solid, and powder can be used.
The blending amount of the novolak type phenol resin used in the composition of the present invention is not particularly limited, but is preferably 30 to 90% by weight, more preferably 40 to 80% by weight with respect to the entire composition. When the amount of the novolak-type phenol resin exceeds the upper limit, the composition may be insufficiently cured. On the other hand, when the amount is less than the lower limit, the resin cures faster and the fluidity during molding is reduced. Therefore, the mechanical strength of the cured product may decrease.

  The resol-type phenolic resin used in the composition of the present invention usually comprises phenols and aldehydes, alkali metal hydroxides, tertiary amines, alkaline earth metal oxides and hydroxides, alkaline substances. In the presence of an alkaline catalyst such as, the reaction molar ratio (F / P) of aldehydes (F) to phenols (P) is preferably 0.7 to 3.0, more preferably 0.9 to 1.8.

Although it does not specifically limit as phenols used here, For example, phenol, such as phenol, orthocresol, metacresol, paracresol, xylenol, para tertiary butylphenol, paraoctylphenol, paraphenylphenol, bisphenol A, bisphenol F, resorcinol Usually, phenol and cresol are often used. Similarly, although not particularly limited as aldehydes, for example, aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, or a mixture thereof, a substance that generates these aldehydes, or these aldehydes Although a similar solution can be used, usually formaldehyde is often used. The form of the resol-type phenol resin thus obtained is not particularly limited, and any form such as liquid, solid, and powder can be used.
The blending amount of the resol type phenol resin used in the composition of the present invention is not particularly limited, but is preferably 2 to 50% by weight, more preferably 5 to 40% by weight with respect to the entire composition. If the amount of the resol-type phenol resin is less than the lower limit, the composition may be insufficiently cured. On the other hand, if the upper limit is exceeded, the resin will be cured faster and the fluidity during molding will be reduced. Therefore, the mechanical strength of the cured product may decrease.

  Although it does not specifically limit as an alkyl substituted aromatic hydrocarbon resin used in the composition of this invention, For example, toluene resin, xylene resin, mesitylene resin etc. can be used. These can be used alone or in combination.

  The blending amount of the alkyl-substituted aromatic hydrocarbon resin in the composition of the present invention is not particularly limited, but is preferably 5 to 50% by weight, more preferably 10 to 40% by weight with respect to the entire composition. It is. If the amount of the alkyl-substituted aromatic hydrocarbon resin is less than the lower limit, the effect of low wear may not be sufficiently obtained, whereas if the upper limit is exceeded, the resin component is not sufficiently cured. As a result, it may be difficult to obtain sufficient mechanical strength as a cured product.

  The method for adding the alkyl-substituted aromatic hydrocarbon resin in the composition of the present invention is not particularly limited, but when the novolac type phenol resin is produced, it may be dissolved in phenols in advance or the novolac type phenol. You may add during resin manufacture. As a result, a phenol resin obtained by blending a novolac-type phenol resin and an alkyl-substituted aromatic hydrocarbon resin is obtained, and a part of the novolac-type phenol resin is the alkyl-substituted aromatic hydrocarbon. A phenol resin composition modified with a resin can be obtained.

  The epoxy resin used in the composition of the present invention is not particularly limited, but may be one having at least two epoxy groups in one molecule and solid or liquid at room temperature, for example, bisphenol A type, bisphenol S type, phenol novolak type, cresol novolak type, biphenyl type, naphthalene type, aromatic amine type and the like. Moreover, these can be used individually or in combination of multiple.

  Although the compounding quantity of the said epoxy resin in the composition of this invention is not specifically limited, It is preferable that it is 2 to 50 weight% with respect to the whole composition, More preferably, it is 5 to 40 weight%. If the compounding amount of the epoxy resin is less than the lower limit value or exceeds the upper limit value, the resin component may be insufficiently cured, which makes it difficult to obtain sufficient mechanical strength as a cured product. There is.

  The curing catalyst used in the composition of the present invention is not particularly limited. For example, tertiary amine compounds such as triethylamine, benzyldimethylamine, and α-methylbenzyldimethylamine, organic phosphine compounds such as triphenylphosphine and tributylphosphine, Examples include imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole. Moreover, these can be used individually or in combination of multiple. Although it does not specifically limit as addition amount of a curing catalyst, It is preferable that it is 0.1-10 weight% with respect to the whole composition, More preferably, it is 0.5-6 weight%. If the addition amount of the curing catalyst is less than the lower limit value, the resin may be insufficiently cured. On the other hand, if the upper limit value is exceeded, the resin cures faster and the fluidity during molding decreases. The mechanical strength of the cured product may be reduced.

  In the resin composition for a friction material of the present invention, uniformly melting and mixing means that the novolac type phenol resin, the resol type phenol resin, the alkyl-substituted aromatic hydrocarbon resin, the epoxy resin, and the curing catalyst melt and flow. It is to mix uniformly in a state where the curing of the phenol resin and the epoxy resin does not substantially occur. The method for producing the resin composition for a friction material according to the present invention is a method in which a novolac type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin, and a curing catalyst are uniformly melt-mixed as described above. . As a preferable example of the method of melt mixing, a predetermined amount of novolak type phenol resin, resol type phenol resin, alkyl-substituted aromatic hydrocarbon resin, epoxy resin, and curing catalyst are charged into a pressure kneader and melted under pressure. It is obtained by mixing. It is preferable to melt and mix at least a novolac-type phenol resin and an epoxy resin and / or a curing catalyst with a pressure kneader. The temperature at the time of mixing is suitably a temperature at which the phenol resin and the epoxy resin melt but do not start curing. As the pressure kneader, a pressure kneader, a twin screw extruder, a single screw extruder, and the like are suitable. Reasons such as increase in resin viscosity or start of gelation reaction when mixing novolac-type phenol resin, resol-type phenol resin, alkyl-substituted aromatic hydrocarbon resin, epoxy resin, and curing catalyst in a normal reaction vessel However, by using a pressure-type kneading apparatus, it is possible to uniformly disperse the phenol resin, the alkyl-substituted aromatic hydrocarbon resin, the epoxy resin, and the curing catalyst.

  In the resin composition for a friction material of the present invention, the free phenol is preferably less than 1% by weight, more preferably less than 0.9% by weight. If the amount of free phenol exceeds the above upper limit, the curability may be adversely affected, and when melt-kneaded, the phenol component volatilizes, which is undesirable in the working environment.

  In general, the friction material according to claim 5 is obtained by mixing a fiber base material composed of organic fibers and inorganic fibers, a filler composed of friction adjustment and the like, and a binder which is the resin composition of the present invention. It is manufactured by thermoforming the raw material composition.

  The fiber substrate used here is not particularly limited, and examples thereof include inorganic fibers such as steel fibers, copper fibers, glass fibers, ceramic fibers, potassium titanate fibers, and organic fibers such as aramid fibers. Moreover, these can be used individually or in combination of multiple. Similarly, the filler is not particularly limited. For example, calcium carbonate, calcium hydroxide, barium sulfate, mica, abrasive, carion, talc, which are inorganic fillers, cashew dust, rubber dust and lubricants which are organic fillers. Examples include graphite, antimony trifluidization, molybdenum disulfide, and zinc disulfide. Moreover, these can be used individually or in combination of multiple.

  As a method for producing the friction material, first, a powder raw material composed of a fiber base material, a filler, and the like, and a binder are weighed at a predetermined composition ratio and mixed in a mixer. As the mixer, for example, a common one such as an Eirich mixer can be used. Next, a predetermined amount of the mixed raw material composition is separated and preformed to form a block body. Thereafter, the preform is put into a mold and thermoformed. For example, the above raw material composition is put into a mold heated to 150 ° C. and pressed to produce a molded body. Then, the friction material is manufactured by heat-processing the molded object produced by this shaping | molding process, for example at 200 degreeC or more, and making it harden | cure.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples. Further, “parts” and “%” described in Examples and Comparative Examples all indicate “parts by weight” and “% by weight”.
Example 1
To a flask equipped with a stirrer, 1000 parts of phenol, 600 parts of xylene resin (Nicanol L, Fudo Co., Ltd.) and 10 parts of oxalic acid were added and refluxed for 1 hour. To this, 400 parts of 37% aqueous formaldehyde solution was added over 1 hour, and the mixture was further refluxed for 1 hour. And the normal pressure removal of the water which arises by reaction, and the vacuum removal were performed until free phenol became less than 1%, and the xylene modified novolak-type phenol resin (1) was obtained.
In a twin screw extruder controlled at an inlet temperature of 90 ° C. and an outlet temperature of 100 ° C., 800 parts of xylene-modified novolac type phenol resin (1), 75 parts of resole type phenol resin (PR-11078 manufactured by Sumitomo Bakelite Co., Ltd.), 150 parts of an epoxy resin (Araldite ECN1299 manufactured by Asahi Ciba Co., Ltd.) and 8 parts of triphenylphosphine were supplied so that the supply amount per unit time was equal, and 900 parts of a solid resin composition at room temperature was obtained from the outlet. 900 parts of the obtained solid resin composition was pulverized to obtain 890 parts of a powdered resin composition.

Example 2
To a flask equipped with a stirrer, 1000 parts of phenol, 400 parts of mesitylene resin (Nicanol G manufactured by Fudo Co., Ltd.) and 10 parts of oxalic acid were added and refluxed for 1 hour. To this, 400 parts of 37% aqueous formaldehyde solution was added over 1 hour, and the mixture was further refluxed for 1 hour. And the normal pressure removal of the water which arises by reaction and vacuum removal until free phenol became less than 1% were performed, and the mesitylene modified novolak-type phenol resin (2) was obtained.
In a pressure kneader, 800 parts of mesitylene-modified novolak type phenolic resin (2), 75 parts of resol type phenolic resin (PR-11078 manufactured by Sumitomo Bakelite Co., Ltd.), 150 parts of epoxy resin (Araldite ECN1299 manufactured by Asahi Ciba Co., Ltd.), 5 parts of triethylamine was charged, heated to 90 ° C. and melted, mixed for 30 minutes, taken out from a pressure kneader, and 900 parts of a resin composition solid at room temperature was obtained. 900 parts of the obtained solid resin composition was pulverized to obtain 890 parts of a powdered resin composition.

Comparative Example 1
800 parts of novolak type phenolic resin (Sumitomo Bakelite Co., Ltd. PR-50731), 100 parts of resol type phenolic resin (PR-11078 made by Sumitomo Bakelite Co., Ltd.), 200 parts of epoxy resin (Araldite ECN1299 made by Asahi Ciba Co., Ltd.) , 10 parts of triphenylphosphine are fed to a twin screw extruder controlled at an inlet temperature of 90 ° C. and an outlet temperature of 100 ° C. so that the supply amount per unit time is equal, and 1000 parts of a solid composition at room temperature from the outlet Got. 1000 parts of the obtained solid composition was pulverized to obtain 990 parts of a powder composition.

Comparative Example 2
In the same manner as in Example 1, a xylene-modified novolak type phenol resin was obtained.
A pressure kneader is charged with 800 parts of this xylene-modified novolak type phenolic resin, 400 parts of an epoxy resin (Araldite ECN1299 manufactured by Asahi Ciba Co., Ltd.) and 15 parts of triphenylphosphine, heated to 90 ° C., melted, and mixed for 30 minutes. Was taken out from the pressure kneader to obtain 1100 parts of a solid resin composition at room temperature. 100 parts of the obtained solid resin composition was pulverized to obtain 990 parts of a powdered resin composition.

Comparative Example 3
1000 parts of a novolac type phenolic resin (PR-50731 manufactured by Sumitomo Bakelite Co., Ltd.) and 100 parts of hexamethylenetetramine were charged into a pulverizer and pulverized to obtain 1090 parts of a powdered resin composition.

The following evaluation was performed about the composition of the powder obtained by the Example and the comparative example.
1. Evaluation of Composition A glass test tube was immersed in an oil bath set at 180 ° C. and allowed to stand until the temperature was stabilized. Thereafter, about 3 g of the precisely weighed composition was placed in a cylindrical aluminum foil and inserted into a tube. While lowering the liquid level by the volume obtained by subtracting the generated gas with a simple gas volume meter, the volume of the gas generated during 10 minutes was measured while keeping the pressure constant. Table 2 shows the measurement results of the gas generation amount.

2. Evaluation of moldability Compositions obtained in Examples and Comparative Examples, aramid fibers as a fiber base material, calcium carbonate and barium sulfate as inorganic fillers, charged and mixed at the blending ratio shown in Table 1, and friction A mixture for materials was used. When 160 g of this friction material mixture was molded at a pressure of 30 MPa, the time required to obtain a molded product having a thickness of 15 mm was measured. Molding temperature evaluated about 175 degreeC, 200 degreeC, and 225 degreeC. Table 2 shows the results of molding temperature and molding time.

3. Evaluation of friction material Using compositions obtained in Examples and Comparative Examples, aramid fiber as a fiber base material, and calcium carbonate and barium sulfate as inorganic fillers, charging and mixing at the blending ratio shown in Table 1, friction A mixture for materials was used. This friction material mixture was molded at a temperature of 150 ° C. and a pressure of 30 MPa for 10 minutes to obtain a molded product of 150 × 150 × 20 mm. The obtained molded product was baked at 200 ° C. for 5 hours to prepare a sample for evaluation corresponding to the friction material, and the following evaluation was performed using the sample. The measurement results are shown in Table 2.

(1) Materials used for the friction material mixture Aramid fiber: Dry pulp Fiber length 2mm
2. Calcium carbonate: average particle size 20μm
3. Barium sulfate: average particle size 20μm

(2) Evaluation method Normal bending strength: measured in accordance with JIS K 7203.
2. Bending strength after heat history: measured at 350 ° C. for 4 hours, cooled, and measured according to JIS K 7203.
3. Hot bending strength: measured at 280 ° C. for 1 hour without cooling and according to JIS K 7203.
4). Coefficient of friction: measured by JASO C 406 using a 1/10 scale dynamometer. The measurement conditions were an initial braking speed of 50 km / h, a deceleration of 0.3 G, a braking frequency of 1000 times, and braking temperatures of three levels of 100 ° C., 200 ° C., and 300 ° C.
5). Abrasion amount: Using a micrometer, the thickness of the test piece before and after the measurement of the friction coefficient was measured and used as the abrasion amount at each braking temperature.

  Each of Examples 1 and 2 is a composition for a friction material according to the present invention containing a novolac-type phenol resin, a resol-type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin, and a curing catalyst. Gas evolution was observed. When a molded article corresponding to the friction material was produced using this composition, degassing was not performed. As a result of evaluating this molded product, it was possible to improve the hot bending strength and reduce the wear amount without affecting the normal bending strength and the average friction coefficient. On the other hand, Comparative Example 1 was a composition in which a novolac type phenol resin, a resol type phenol resin, an epoxy resin, and a curing catalyst were blended, but the composition of Comparative Example 1 does not contain an alkyl-substituted aromatic hydrocarbon resin. As a result of the evaluation of the molded product, the amount of wear increased compared to the example. Moreover, although the comparative example 2 was set as the composition which mix | blended the novolak-type phenol resin, the epoxy resin, and the curing catalyst, the composition of the comparative example 2 does not contain a resol type phenol resin and an alkyl substituted aromatic hydrocarbon resin. Therefore, as a result of the evaluation of the molded product, a decrease in hot bending strength and an increase in the amount of wear were observed as compared with the examples. Comparative Example 3 was a composition in which hexamethylenetetramine was blended with a novolac-type phenol resin, and a large amount of gas was generated during curing. When a molded product corresponding to the friction material was produced using this composition, degassing was performed four times during molding. For reference, molding without a degassing operation was attempted, but gas swelled and a good molded product could not be obtained. Although molding was possible at 175 ° C., swelling at 200 ° C. and 225 ° C. was caused by gas, and a good molded product could not be obtained.

Claims (5)

  A phenol resin composition for a friction material, characterized by uniformly melting and mixing a novolac type phenol resin, a resol type phenol resin, an alkyl-substituted aromatic hydrocarbon resin, an epoxy resin and a curing catalyst.   The proportion of each component is 30 to 90% by weight of novolak type phenol resin, 2 to 50% by weight of resol type phenol resin, 5 to 50% by weight of alkyl-substituted aromatic hydrocarbon resin, 2 to 50% by weight of epoxy resin, and 0. The phenol resin composition for a friction material according to claim 1, wherein the content is 1 to 10% by weight.   The phenol resin composition for a friction material according to claim 1 or 2, wherein free phenol in the composition is less than 1% by weight.   It is a manufacturing method which manufactures the phenol resin composition for friction materials of any one of Claims 1-3, Comprising: At least a novolak-type phenol resin, an epoxy resin, and / or a curing catalyst are fuse | melted with a pressure-type kneading apparatus. A method for producing a phenol resin composition for a friction material, comprising mixing.   The friction material which uses the phenol resin composition for friction materials of any one of Claims 1-3.