JP3075951B2 - Resin composition for friction material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder used for obtaining a friction material which does not lower the friction coefficient at high temperatures, has little wear, and has excellent heat resistance. The present invention relates to a friction material resin composition having excellent heat resistance and heat resistance.

[0002]

2. Description of the Related Art Friction materials such as brake linings, disc pads, and clutch facings are used in automobiles and industrial machines for braking or transmitting power. These friction materials are generally made of a base material such as glass fiber, aramid fiber, and metal fiber, and an organic additive such as cashew dust, melamine dust, and rubber dust, and an inorganic additive such as barium sulfate, calcium carbonate, wollastonite, and copper powder. Are combined with a phenolic resin.

[0003] With the recent increase in output and performance of automobiles, these friction materials have a braking stability under severe conditions, that is, a stable friction coefficient at high temperatures, and a high wear resistance at high temperatures. Reduction is strongly demanded. This is because when kinetic energy is converted to heat energy when the friction material obtains braking due to friction with the partner material, the friction material reaches a considerably high temperature, and at that time, the friction material wears due to decomposition of the organic binder. Also, a decomposition product such as a tar component generated by the decomposition causes a decrease in the friction coefficient generally called a fade. In order to prevent these high-temperature wear and a decrease in the coefficient of friction, the heat resistance of the friction material, that is,
Heat resistance of a phenolic resin serving as a binder is required.

[0004] In order to improve such performances, researches on modified phenolic resins have been actively conducted, and oil-modified phenolic resins, cashew-modified phenolic resins, epoxy-modified phenolic resins, melamine-modified phenolic resins, and the like have been studied. Some are in practical use. However, these modified phenolic resins have insufficient heat resistance.

[0005] For the purpose of improving heat resistance, various aromatic hydrocarbon-modified phenol resins have been studied. For example, oxygen-containing xylene formaldehyde resin produced from meta-xylene and formaldehyde and phenol, hydrochloric acid,
There is an aromatic hydrocarbon-modified phenol resin produced by a method of reacting with an inorganic acid such as sulfuric acid or an organic acid such as p-toluenesulfonic acid and then further adding formaldehyde to further react the remaining phenol. However, the resulting modified phenolic resin has good moisture resistance and hot flexibility, but has insufficient heat resistance. In order to improve the heat resistance, it has been proposed to use a highly reactive oxygen-containing aromatic hydrocarbon formaldehyde resin having very few methylene bonds (Japanese Patent Publication No. 55-9013). However, the heat resistance of the composite material depends not only on the high chemical heat resistance of the binder used, but also on the adhesion between the binder and the substrate, and the flow hardening characteristics of the binder. Met.

It is believed that thermal decomposition of phenolic resin is caused by oxidative thermal decomposition at a methylene bridge between phenol nuclei. By replacing one side of the methylene bridge with an aromatic hydrocarbon having no phenolic hydroxyl group, chemical heat resistance can be improved. Is improved. That is, in the reaction between phenol and an aromatic hydrocarbon, the chemical heat resistance as a binder increases in proportion to the amount of modification of the aromatic hydrocarbon. On the other hand, when the amount of modification of the aromatic hydrocarbon is increased, the phenolic hydroxyl group content is reduced as a whole, so that the adhesion to the base material is reduced,
Defects such as deterioration of moldability due to decrease in reactivity and deterioration of fluid curability due to increase in molecular weight increased, and sufficient heat resistance as a composite material could not be obtained. Therefore, as a result of examining the compatibility between the chemical heat resistance of the binder and the adhesion to the base material, which were previously incompatible, it was found that bisphenol A
By reacting a certain amount of an aromatic hydrocarbon formaldehyde resin with the phenol resin composition, it was possible to obtain a phenol resin composition having both excellent chemical heat resistance as a binder and excellent adhesion to a base material. The aromatic hydrocarbon chain to be introduced is long, and there is a problem in moldability, and the heat resistance is not sufficient in applications where the crosslinking density is low and stricter heat resistance is required.

[0007]

SUMMARY OF THE INVENTION The present invention has been completed as a result of various studies in order to solve such problems of the phenolic resin, and the object thereof is to reduce the coefficient of friction at high temperatures. Without, and a binder used to obtain a friction material excellent in heat resistance with less wear,
The present invention relates to a resin composition for a friction material having excellent moldability, adhesion to a substrate, and heat resistance. The present invention uses, as a main component, a polycondensate of bisphenol A and xylene glycols, and has excellent chemical heat resistance as a binder and excellent adhesion to a base material, and has good moldability and after curing. A phenolic resin for a friction material having a high crosslinking density was obtained, and it was confirmed that the heat resistance of the friction material was remarkably improved, and various studies were further advanced to complete the present invention.

[0008]

SUMMARY OF THE INVENTION The present invention is a resin composition comprising a polycondensate of bisphenol A and xylene glycol or a derivative thereof as a main component.

In the polycondensate of bisphenol A and xylene glycol or a derivative thereof, the molar ratio of xylene glycol to bisphenol A is 0.5 to 0.5.
0.9 is preferred, and when it is 0.5 or less, the effect of improving the chemical heat resistance as a binder is low. Occurs.

Examples of xylene glycol or its derivative include para-xylene glycol dimethyl ether, para-xylene glycol, meta-xylene glycol dimethyl ether, meta-xylene glycol, ortho-xylene glycol dimethyl ether, and ortho-xylene glycol, and these may be used alone or in combination of two or more. May be used.

As the polycondensation catalyst, organic acids such as oxalic acid, paratoluenesulfonic acid, xylenesulfonic acid and phenolsulfonic acid, and inorganic acids such as hydrochloric acid and sulfuric acid can be used. The amount of the catalyst added was 0.01 to 3.0 with respect to the total charged amount.
A range of weight percent is common. The molar ratio of xylene glycols to bisphenol A in the resin is 1
It can be calculated by 3C-NMR or the like.

Bisphenol A obtained as described above
-If necessary, organic or inorganic additives and fillers may be added to the xylene glycol polycondensate. Further, the mixing of these components may be simply pulverization mixing, solution mixing or melt mixing, and the obtained resin composition may take any form of powder, solid, and liquid.
Bisphenol A / xylene glycol polycondensate is a kind of phenolic resin due to its chemical structure. As a curing agent for crosslinking this, a general phenolic resin curing agent such as hexamethylenetetramine can be used. it can. The mixing ratio of hexamethylenetetramine is usually 3 to 20 parts by weight based on 100 parts by weight of the polycondensate. If the amount is less than 3 parts by weight, the crosslinking density is low, and the properties as a friction material are insufficient. If the amount exceeds 20 parts by weight, gas is generated at the time of curing, and the crosslinking density becomes too high, and the characteristics as a friction material deteriorate. Other phenolic resins can be mixed with such a resin composition and used. In this case, the mixing ratio of the other phenolic resin is usually 100 parts by weight or less based on 100 parts by weight of the polycondensate. If it exceeds this, the effect of improving the heat resistance as a binder for the friction material becomes small.

[0013]

The present invention will be described below with reference to examples. However, the present invention is not limited by these examples. Further, “parts” and “%” described in Production Examples, Examples and Comparative Examples all indicate “parts by weight” and “% by weight”.

<< Production Example 1 >> 1000 parts of bisphenol A, 570 parts of para-xylene glycol dimethyl ether and 0.6 parts of diethyl sulfuric acid were charged into a reactor equipped with a stirrer, a reflux condenser and a thermometer, and then gradually dehydrated under normal pressure. After the temperature reached 160 ° C., a normal pressure dehydration reaction was performed for 180 minutes. Next, while the inside of the system was dehydrated under a vacuum of 650 mmHg, when the temperature in the system was raised to 160 ° C., it was taken out of the reactor and solid resin 137 was formed at room temperature.
0 parts were obtained.

<< Production Example 2 >> 1370 parts of a solid resin at ordinary temperature were obtained in the same manner as in Production Example 1 except that 473 parts of para-xylene glycol were used instead of 570 parts of para-xylene glycol dimethyl ether. << Production Example 3 >> 1370 parts of a solid resin at room temperature were obtained in the same manner as in Production Example 1 except that orthoxylene glycol dimethyl ether was used instead of para-xylene glycol dimethyl ether.

<< Preparation Example 4 >> Into the same reactor as in Preparation Example 1, 1000 parts of phenol, 630 parts of 37% formalin and 20 parts of oxalic acid were charged, and the temperature was gradually increased to reach 95 ° C. and refluxed for 120 minutes. The reaction was performed. Next, 6
While dehydrating under a vacuum of 50 mmHg, the temperature in the system was raised to 190 ° C. to obtain 1080 parts of a novolak type solid phenol resin having a melting point of 100 ° C.

Example 1 Resin 10 obtained in Production Example 1
To 100 parts, 110 parts of hexamethylenetetramine was added and pulverized to obtain a powdered resin composition. Example 2 To 1000 parts of the resin obtained in Production Example 2, 110 parts of hexamethylenetetramine was added and pulverized to obtain a powdered resin composition. Example 3 To 1000 parts of the resin obtained in Production Example 3, 110 parts of hexamethylenetetramine was added and pulverized to obtain a powdered resin composition. Example 4 110 parts of hexamethylenetetramine was added to 800 parts of the resin obtained in Production Example 1 and 200 parts of the resin obtained in Production Example 4 and pulverized to obtain a powdered resin composition. Comparative Example 1 To 1000 parts of the resin obtained in Production Example 4, 110 parts of hexamethylenetetramine was added and pulverized to obtain a powdered resin composition.

The four types of resins obtained in Examples 1, 2, 3 and Comparative Example 1 were separately charged and mixed at the mixing ratios shown in the following table. Compounding ratio 配合 Compounding compounding amount (% by weight) ───────────────── Glass fiber 20 Calcium carbonate 70 Powder resin composition 10１０ This composition was molded at a temperature of 160 ° C under a pressure of 200 kg / cm ² for 10 minutes, and then baked at 180 ° C for 3 hours. -Was prepared. Table 1 shows the evaluation results of the test pieces of the obtained four resin compositions based on the normal bending strength and the bending strength after the heat history.

[0019]

[Table 1]

As is clear from Table 2, Examples 1, 2,
Sample No. 3 shows little deterioration in bending strength after heat history and is excellent in heat resistance.

[0021]

The friction material using the resin composition of the present invention as a binder has excellent heat resistance and is suitable for braking parts of automobiles, railway vehicles, aircraft, and industrial machines.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 61/00-61/12 C08J 5/14 C08L 65/00-65/04 F16D 69/02

Claims (1)

(57) [Claims] 1. A resin composition for a friction material, comprising a polycondensate of bisphenol A and xylene glycol or a derivative thereof as a main component.