JP2009035662A - Phenol resin composition for friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin composition for a friction material requiring no degasification when molded, forming no void or crack in molded articles, excellent in flexibility and having good heat resistance and to provide a method for producing the phenol resin composition. <P>SOLUTION: The phenol resin composition for friction material comprises an unsaturated oil-modified novolak type phenol resin, a resol type phenol resin, a thermoplastic resin, an epoxy resin and a curing catalyst as essential components. An unsaturated oil used for the unsaturated oil-modified novolak type phenol resin is preferably at least one oil selected from a group consisting of cashew oil, tall oil, linseed oil and wood oil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phenol resin composition for a friction material.

A phenol resin is a material having excellent mechanical properties, electrical properties, adhesiveness, and the like, but a molded product using the phenol resin has a drawback of being hard and brittle. A modification method using an elastomer such as rubber is effective as a method for improving the brittleness of a phenol resin and strengthening it, and many studies have been conducted. As an example, there is an elastomer-modified phenol resin modified with an acrylic ester-containing elastomer or the like (see, for example, Patent Document 1). However, there is a drawback that the heat resistance of the phenol resin is impaired by modification with an elastomer.
On the other hand, conventional phenol resin compositions for friction materials are generally based on novolak type phenol resins using hexamethylenetetramine as a curing agent, or resol type phenol resins alone or in combination with novolac type phenol resins. Met. When such a phenol resin composition is used, ammonia gas generated by decomposition of condensed water and hexamethylenetetramine is generated during molding, that is, in the curing reaction of the resin. Water vapor and ammonia gas resulting from these condensed waters inhibit uniform resin curing and cause voids, cracks, etc. in the molded product, resulting in poor appearance of the molded product, reduced mechanical strength, etc. There is a problem, and in order to avoid this, it is necessary to perform a degassing operation at the time of molding, and there is a problem that the process is complicated and takes a long time, resulting in poor efficiency and workability. 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 2). However, such a phenol resin composition for a friction material has a problem in that strength is reduced when exposed to a high temperature.
JP-A-10-007815 Japanese Patent Laid-Open No. 2001-213941

The present invention provides a phenol resin composition for a friction material that does not require degassing during molding, does not cause voids or cracks in a molded product, has excellent flexibility, and has good heat resistance.

Such an object is achieved by the following present inventions [1] to [3].
[1] A phenol resin composition for a friction material comprising an unsaturated oil-modified novolak-type phenol resin, a resol-type phenol resin, an epoxy resin, and a curing catalyst.
[2] The phenol resin for a friction material according to claim 1, wherein the unsaturated oil-modified novolak type phenol resin is one or more selected from the group consisting of cashew oil, tall oil, linseed oil and tung oil. Composition.
[3] The phenol resin composition for a friction material according to claim 1, wherein the novolac-type phenol resin has a modification rate of unsaturated oil of 5 to 50% by weight.
[4] The phenol resin composition for a friction material according to claim 1 or 3, wherein the unsaturated oil is cashew oil.

  According to the present invention, it is possible to provide a phenol resin composition for a friction material that does not require degassing during molding, does not cause voids or cracks in a molded product, and has excellent flexibility and heat resistance. it can.

Hereinafter, the phenol resin composition of the present invention will be described.
The phenol resin composition for a friction material of the present invention contains an unsaturated oil-modified novolac type phenol resin, an epoxy resin, a resol type phenol resin, and a curing catalyst as essential components.

The unsaturated oil-modified novolak-type phenol resin used in the phenol resin composition for a friction material of the present invention is generally phenols (P) and aldehydes (F) using phenols and aldehydes as acidic catalysts. After the reaction, those modified with an unsaturated oil are preferably used. Although it does not specifically limit as reaction molar ratio [F / P] at the time of making the said phenols and aldehydes react, It is preferable that it is 0.5-1.0, More preferably, it is 0.6-0. Nine. When the molar ratio is less than the lower limit, the molecular weight of the resin is low, and a solidified resin cannot be obtained. On the other hand, if the molar ratio exceeds the above upper limit, it is impossible to terminate the reaction properly due to thickening or gelation due to polymerization of the resin during the resinification reaction.

  Examples of acidic substances that can be used as catalysts for unsaturated oil-modified novolak type phenolic resins include organic acids such as oxalic acid, mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, paratoluenesulfonic acid, and paraphenolsulfonic acid. Can do. Moreover, these can be used individually or in combination of 2 or more types.

Although it does not specifically limit as unsaturated oil used for the synthesis | combination of an unsaturated oil modified novolak type phenol resin, For example, cashew oil, tall oil, linseed oil, tung oil, etc. can be used. These can be used alone or in combination of two or more.
Modification by unsaturated oil can be obtained by reacting phenols (P) and aldehydes (F), adding unsaturated oil, and reacting oxalic acid or the like as a catalyst.

The amount of modification of the unsaturated oil-modified novolak type phenol resin is preferably 5 to 50% by weight, more preferably 10 to 35% by weight. If the modification amount is less than the lower limit, there is a problem that the obtained resin lacks flexibility, and if the modification amount exceeds the upper limit, a problem that the curability is impaired is not preferable.

The resol type phenol resin used in the phenol resin composition for a friction material of the present invention usually reacts phenols (P) and aldehydes (F) using a basic substance as a catalyst with phenols and aldehydes. Are preferably used. Although it does not specifically limit as reaction molar ratio [F / P] at the time of making the said phenols and aldehydes react, It is preferable that it is 0.7-3.0, More preferably, it is 0.9-1. 8.

Examples of the basic substance that can be used as a catalyst for the resol type phenol resin include alkali metal hydroxides, tertiary amines, alkaline earth metal oxides and hydroxides, and alkaline substances. Moreover, these can be used individually or in combination of 2 or more types.

Although it does not specifically limit as phenols used as a raw material of unsaturated oil modification novolak type phenol resin or resol type phenol resin, For example, cresol, such as phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, xylenol such as 3,5-xylenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, etc. Alkylphenols such as ethylphenol, isopropylphenol, butylphenol, p-tert-butylphenol, p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol, fluorophenol Halogenated phenols such as chlorophenol, bromophenol and iodophenol, monovalent phenol substitutes such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol and trinitrophenol, and 1 such as 1-naphthol and 2-naphthol And polyhydric phenols such as divalent phenols, resorcinol, alkylresorcinol, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, phloroglucin, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalene and the like. These can be used singly or in combination of two or more, but usually phenol and cresol are often used.

Next, the aldehydes used as a raw material for the novolac type phenol resin or the resol type phenol resin are not particularly limited. For example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural , Glyoxal, n-butyraldehyde, caproaldehyde, allyl aldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde and the like. These can be used alone or in combination of two or more, but usually formaldehydes such as formaldehyde and paraformaldehyde are often used.

  The content of unreacted phenols in the unsaturated oil-modified novolak-type phenol resin or resol-type phenol resin used in the phenol resin composition for a friction material of the present invention is 5.0% by weight or less based on the entire novolak-type phenol resin. It is preferable that it is 1.0% by weight or less. By doing so, the odor at the time of resin processing due to unreacted phenol can be reduced, the working environment can be made favorable, and the original physical properties can be kept good.

Although it does not specifically limit as an epoxy resin used for the phenol resin composition for friction materials of this invention, It is a thing which has at least 2 epoxy group in 1 molecule and is solid 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. The compounding amount of the epoxy resin in the composition of the present invention is not particularly limited, but the epoxy group of the epoxy resin is 0.1 to 2.5 equivalents with respect to 1.0 equivalent of the phenolic hydroxyl group of the novolac type phenol resin. It is preferable that it is 0.2-1.4 equivalent. If the number of equivalents of epoxy groups relative to the phenolic hydroxyl group is less than the above lower limit value or exceeds the above upper limit value, the resin component may be insufficiently cured, whereby the cured product has sufficient mechanical strength. It may not be obtained.

Although it does not specifically limit as a curing catalyst used in the phenol resin composition for friction materials of this invention, For example, tertiary amine compounds, such as triethylamine, benzyldimethylamine, (alpha) -methylbenzyldimethylamine, triphenylphosphine, tributylphosphine, etc. Examples include organic phosphine compounds, 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 0.03-2.5 weight part with respect to 100 weight part of epoxy resins, More preferably, it is 0.05-2.0 weight part. If the addition amount of the curing catalyst is less than the lower limit, curing of the resin may be insufficient. On the other hand, if the amount exceeds the upper limit, the curing of the resin is accelerated and the fluidity is lowered. May cause a decrease in strength.

The phenol resin composition of the present invention is superior in flexibility to a phenol resin composition for a friction material prepared using a normal novolac type phenol resin, and only a novolac type phenol resin modified with a thermoplastic resin as a resin component. Does not require a lot of degassing during molding of the composition used, does not cause voids or cracks in the molded product, and has good heat resistance against phenol resin composition for friction material of epoxy resin curable type A phenol resin composition for a friction material can be provided.

Hereinafter, the examples using the composition of the present invention as a friction material will be described in detail.
The raw materials used in the preparation of each composition and the production of the friction material (brake material) in the examples are as follows.
(1) Novolac type phenolic resin: PR-50731 manufactured by Sumitomo Bakelite Co., Ltd.
(2) Resol type phenol resin: Sumitomo Bakelite Co., Ltd. PR-11078
(3) Epoxy resin: Araldite ECN1299 manufactured by Asahi Ciba Co., Ltd.
(4) Barium sulfate (average particle size 20 μm): BF-1H manufactured by Sakai Chemical Co., Ltd.
(5) Calcium carbonate (average particle size 20 μm): Vigot 15 manufactured by Shiroishi Kogyo Co., Ltd.
(6) Hexamethylenetetramine: Caldic Europoprt. V.
(7) Cashew dust (average particle size 250 μm): FF-1081 manufactured by Tohoku Kako Co., Ltd.
(8) Aramid fiber (fiber length 2 mm): dry pulp manufactured by Toray DuPont Co., Ltd.

Example 1
A flask equipped with a stirrer was charged with 1000 parts by weight of phenol and 10 parts by weight of oxalic acid. 604 parts by weight of 37% formaldehyde aqueous solution was added to this over 1 hour and a half (F / P ratio = 0.7), and the mixture was further refluxed for 1 hour to remove atmospheric pressure of water generated by the reaction, and free phenol was reduced to less than 1%. Vacuum removal was performed until 380 parts by weight of cashew oil was added to obtain a cashew oil-modified novolak phenol resin (1).
600 parts by weight of this cashew oil-modified novolak type phenolic resin (1), 200 parts by weight of solid resol type phenolic resin, 200 parts by weight of epoxy resin, and 1 part by weight of triphenylphosphine were softened and mixed by applying pressure and shearing force with a kneader. 950 parts by weight of a solid phenol resin composition for friction material was obtained. Furthermore, this was grind | pulverized with the grinder, and 900 weight part of powdery phenol resin compositions (1) for friction materials were obtained.
80 parts by weight of the obtained phenol resin composition for friction material (1), 400 parts by weight of barium sulfate, 420 parts by weight of calcium carbonate, 50 parts by weight of cashew dust, and 50 parts by weight of aramid fibers were mixed with an Eirich mixer. A mixture was obtained.
This was molded at a temperature of 150 ° C. and a pressure of 30 MPa for 9 minutes to obtain a molded product of 85 × 60 × 18 mm. The obtained molded product was further fired at 200 ° C. for 5 hours to obtain a friction material (brake material).

(Comparative Example 1)
In the same manner as in Example 1, a cashew oil-modified novolak-type phenol resin (1) was obtained.
600 parts by weight of this cashew oil-modified novolak type phenol resin (1), 400 parts by weight of epoxy resin, and 2 parts by weight of triphenylphosphine are softened and mixed by applying pressure and shearing force with a kneader to form a solid phenol resin composition for friction material 950 parts by weight were obtained. This was further pulverized by a pulverizer to obtain 900 parts by weight of a powdery phenol resin composition for a friction material.
Using the obtained phenol resin composition for a friction material, the same operation as in Example 1 was performed at a blending ratio shown in Table 2 to obtain a friction material.

(Comparative Example 2)
A composition of 600 parts by weight of a novolac type phenol resin, 200 parts by weight of a resol type phenol resin, 200 parts by weight of an epoxy resin, and 1 part by weight of triphenylphosphine by applying pressure and shearing force with a kneader to soften and mix the solid phenol resin composition 950 parts by weight of product was obtained. This was further pulverized by a pulverizer to obtain 900 parts by weight of a powdery phenol resin composition for a friction material.
Using the obtained phenol resin composition for a friction material, the same operation as in Example 1 was performed at a blending ratio shown in Table 2 to obtain a friction material.

(Comparative Example 3)
In the same manner as in Example 1, a cashew oil-modified novolak-type phenol resin (1) was obtained.
600 parts by weight of this cashew oil-modified novolak type phenol resin (1), 400 parts by weight of novolak type phenol resin, and 100 parts by weight of hexamethylenetetramine are softened and mixed by applying pressure and shearing force with a kneader to form a solid phenol resin for friction material. 1050 parts by weight of the composition was obtained. Further, this was pulverized with a pulverizer to obtain 1000 parts by weight of a powdery phenol resin composition for a friction material.
Using the obtained phenol resin composition for a friction material, the same operation as in Example 1 was performed at a blending ratio shown in Table 2 to obtain a friction material.

Table 1 shows the composition of the phenol resin composition for a friction material used for the preparation of the friction material (brake material). Table 2 shows the composition of each material in the preparation of the friction material. All units represent parts by weight.

  The following evaluations were performed using the brake materials produced in the above examples and comparative examples as samples for evaluation. The results are shown in Table 3.

Evaluation Method (1) Gas generation amount: A glass test tube was immersed in an oil bath set at 180 ° C. and left 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.

(2) Moldability: When 160 g of the friction material mixture obtained by charging and mixing at the blending ratio shown in Table 1 was molded at a pressure of 30 MPa, the time required for molding was measured. The molding temperature was evaluated at 175 ° C and 225 ° C.

(2) Rockwell hardness: Measured according to JIS K 7202 “Plastic Rockwell hardness test method”.

(3) Bending strength: Measured according to JIS K 7203 “Bending test method of hard plastic”. The state bending strength was measured at room temperature, and the bending strength after heat treatment was measured at room temperature after heat treatment at 350 ° C. for 4 hours. The bending strength was measured at 300 ° C. for a test piece held at 200 ° C. for 1 hour.

(4) Dynamic viscoelasticity test: Measured using a dynamic viscoelasticity measuring apparatus under a nitrogen stream (300 mL / min) at a temperature rising rate of 3 ° C./min.

Example 1 is a phenol resin composition for a friction material obtained by pulverizing together with a resol type phenol resin and an epoxy resin using a cashew oil-modified novolak type phenol resin.
Comparative Example 1 has a higher proportion of epoxy resin than Example 1 because it does not contain a resol-type phenol resin, and has a large decrease in mechanical properties when heated relative to the normal state.
Comparative Example 2 is a phenol resin composition for a friction material that does not contain a cashew oil-modified novolak type phenol resin, but data with poor flexibility was obtained compared to other examples.
Comparative Example 3 is a phenol resin composition for a friction material that is cured using hexamethylenetetramine without using a resol-type phenol resin and an epoxy resin, but has a large amount of gas generation and causes blistering and cracking at 225 ° C. It was impossible to mold.

Claims (4)

A phenol resin composition for a friction material, comprising an unsaturated oil-modified novolak-type phenol resin, a resol-type phenol resin, an epoxy resin, and a curing catalyst. 2. The friction material according to claim 1, wherein the unsaturated oil used in the unsaturated oil-modified novolak phenol resin is one or more selected from the group consisting of cashew oil, tall oil, linseed oil, and tung oil. Phenolic resin composition. 2. The phenol resin composition for a friction material according to claim 1, wherein the unsaturated oil-modified novolak type phenol resin has a modification rate of 5 to 50% by weight of the unsaturated oil. The phenol resin composition for a friction material according to claim 1 or 3, wherein the unsaturated oil is cashew oil.