JP3240662B2 - Heat resistant resin dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant friction dust for a friction material which functions effectively even at a temperature from room temperature to a high temperature exceeding 350.degree.

[0002]

2. Description of the Related Art Conventionally, as frictional dust for organic friction materials, formalin resins using cashew-nut shell oil, drying oil, etc., and rubbers such as natural rubber and SBR are used as relatively inexpensive materials. Had been. However, these materials are inferior in heat resistance, and lack sufficient mechanical strength when heated and the maximum use temperature.

For example, a rubber-based dust obtained by reheating a used tire or other carbon-containing rubber and pulverizing the rubber-based dust has a heating loss starting temperature of about 150 to 200 ° C., and a 10% weight loss used as a heat resistance index in this field. The temperature is around 200-230 ° C. Further, in a high-temperature state, it has a drawback that it becomes pitch-shaped, and the friction coefficient is greatly reduced.

[0004] Next, the most commonly used cashew
Resin dust has a 10% weight loss temperature in the air of 260-300 ° C
It is thermally decomposed at 520-550 ° C, and the residual carbon ratio after decomposition is extremely low. In addition, as in the case of rubber-based rubber, the rubber composition decomposes through a pitch state at a temperature of about 280 ° C., which may significantly reduce the friction coefficient, which is a major drawback in terms of safety. Further, in the production of cashew resin dust, since a strongly acidic compound is usually used as a catalyst, there is a disadvantage that this remains and metal fillers and the like are easily corroded.

[0005] In addition, a semi-metallic material using steel fiber as a substitute fiber instead of a conventional friction agent using asbestos as a reinforcing base material and a phenol resin as a binding resin.
It is known that a non-asbestos type disc brake pad mainly using a type or an aramid fiber or a carbon fiber generates a remarkable noise of brake squeal during braking.

[0006]

As described above, a heat-resistant resin dust which has solved the problems of the conventional resin dust is surprisingly obtained by adding an aromatic hydrocarbon resin-modified novolak type epoxy resin (I) to a cyanate ester-based resin. Curable resin composition (II)
And a layered inorganic material (III), and the final curing temperature 2
Cured above 00 ℃, but 10% weight loss temperature is 320 ℃
Above, without passing through the liquid state, high carbonization rate, further,
Even at 400 ° C, it maintains a coefficient of friction approximately equal to 100 ° C,
In addition, it has been found that a high friction coefficient is exhibited even at room temperature. As a result, for example, when used as a disc brake pad, the brake squeal is sufficiently reduced, and at the time of high speed, it withstands high temperatures, maintains a sufficient friction coefficient, is excellent in fade resistance, and has low abrasion resistance. And found that the present invention can be manufactured, and completed the present invention.

[0007]

That is, the present invention relates to an aromatic hydrocarbon resin-modified novolak type epoxy resin (I).
(A) a monofunctional or polyfunctional cyanate ester, the cyanate ester prepolymer or a prepolymer of the cyanate ester and an amine, or (a) and (b) the monofunctional or polyfunctional Cyanate ester-based curable resin composition containing maleimide, maleimide prepolymer or prepolymer of maleimide and amine as a main component
It is a heat-resistant resin dust obtained by blending (II) and a layered inorganic substance (III), curing at a final curing temperature of 200 ° C. or more, and pulverizing. The amount of the cyanate ester-based curable resin composition (II) is usually 50% by weight or less, preferably 10% by weight or less.
And the amount of the layered inorganic substance (III) is 5 to 50 parts by weight based on 100 parts by weight of the total of the components (I) and (II).
60 parts by weight, in particular, the layered inorganic substance (III) is a heat-resistant resin dust of synthetic mica or hexagonal boron nitride.

Hereinafter, the present invention will be described. Novolak type epoxy resin modified with aromatic hydrocarbon resin of the present invention (I)
Is obtained by reacting an aromatic hydrocarbon resin, phenols and formaldehyde to obtain an aromatic hydrocarbon resin-modified novolak, reacting the -OH group with epichlorohydrin, and epoxidizing the resin.

Here, as the epoxy resin, an epoxy resin derived from bisphenol A, phenol novolak, cresol novolak or the like is generally used. However, when a bisphenol A type epoxy resin is used in place of the aromatic hydrocarbon resin-modified novolak type epoxy resin (I) of the present invention, heat resistance is inferior, tackiness occurs at high temperatures, and the friction coefficient becomes unstable. Cannot be used because the amount of wear is large. Further, a novolak type epoxy resin made of phenol or cresol is hard and brittle and cannot be used.

As the aromatic hydrocarbon resin as a raw material, mesitylene, xylene, toluene, benzene, naphthalene,
It is obtained by using one or a mixture of two or more other various aromatic hydrocarbons as a raw material, and examples thereof include a mesitylene resin, a xylene resin, a toluene resin, a benzene resin, and a naphthalene resin. In addition, as phenols,
Examples include phenol, cresol, xylenol, resorcinol and the like. Any formaldehyde can be used as long as it generates formaldehyde under the reaction conditions. Furthermore, the reaction using an epichlorohydrin is the simplest and preferable method for the reaction for forming an epoxy resin.

The aromatic hydrocarbon resin-modified novolak is obtained by converting the above aromatic hydrocarbon resin and phenol to an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, an acidic catalyst such as toluenesulfonic acid, xylenesulfonic acid, oxalic acid or acetic acid. After reacting using a neutral catalyst such as calcium, magnesium acetate, zinc acetate, and other metal salts of organic acids, a method of reacting with formaldehyde may be mentioned. It can also be carried out by a method of reacting with a hydrocarbon resin or a method of simultaneously reacting an aromatic hydrocarbon resin, phenols and formaldehyde. In addition, it is preferable not to use hexamethylenetetramine which is usually used as a curing agent.

The ratio of the aromatic hydrocarbon resin to the phenol is preferably substantially the same as the reactive group equivalent of phenol commonly used in the used aromatic hydrocarbon resin. For example, -CH ₂ -OH
, —CH ₂ —O—CH ₂ —, —CH ₂ —O—, and —CH ₂ —O—CH ₂ —OH. If the amount of phenols is too small, gelation occurs in a part of the reaction product, causing an increase in viscosity and unreacted substances remaining due to interruption of the reaction. Becomes unstable at high temperatures. In addition, formaldehyde is also of such an extent that a novolacation reaction occurs.

For example, when using a xylene resin (= xylene formaldehyde resin) having a number average molecular weight of 350 to 800 and an oxygen content of 8 to 17% by weight and reacting it with phenol, xylene resin / phenol = 100/100 250250 (weight ratio), preferably 100 / 100-200. The aromatic hydrocarbon resin-modified novolak obtained by this method is usually a brown solid having a melting point of 60 to 100 ° C.

Reacting a phenolic hydroxyl group in an aromatic hydrocarbon resin-modified novolak with epichlorohydrin,
Epoxidation gives an aromatic hydrocarbon resin-modified novolak epoxy resin. The reaction can be carried out by a known method, and the obtained epoxy resin usually has a melting point of 45 ° C. or higher.

The curable resin composition of the cyanate ester type (II) of the present invention comprises (a) a monofunctional or polyfunctional cyanate ester, the cyanate ester prepolymer or the cyanate ester and an amine. Prepolymer is an essential component, from the aspect of imparting heat resistance (b)
A monofunctional or polyfunctional maleimide, the maleimide prepolymer or a prepolymer of the maleimide and an amine is used by appropriately mixing the epoxy resin (c) from the viewpoint of workability.

The cyanato resin (a) is disclosed in JP-B-41-1928.
No. 45-11712, No. 44-1222, German Patent No. 119018
No. 4, USP-4026913, -4022755, -3448079, -3553244, -3755
402, -3740348, -3595900, -3694410, -4116946, etc., and (a) + (b) or (a) + (b) + (c) cyanate ester-maleimide resin and cyanic acid Ester-
Maleimide-epoxy resins are known from JP-B-54-30440, JP-B-52-31279, USP-4110364 and the like, and (a) + (c) cyanate-epoxy resins are disclosed in JP-B-46-41112. It is publicly known by the number.

When a maleimide component (b) is used in the cyanate ester-based curable resin composition (II) of the present invention, the amount thereof is usually at most 80% by weight of the resin component in the composition (II), preferably Is 30 to 60% by weight, and when an epoxy resin is used, it is preferable to use one having three or more functions, and usually 30% or less, preferably 2 to 10% by weight of the resin component in the composition (II). %. Further, component (a) is preferably the main component.

Examples of the layered inorganic substance (III) of the present invention include flake-like powders such as mica, talc, graphite, and h-BN (= hexagonal boron nitride) and needle-like powders. The average particle diameter may be in the range of 0.1 to 300 μm, but is preferably 1.0 to 200 μm for the purpose of the present invention. Among these, mica (= mica) is preferred, and natural silicate-based minerals such as muscovite (muscovite), phlogovite (phlogopite), biotite (biotite), and other fluorinated fluorine Chemical mica, and further, synthetic mica and the like. In the present invention, it is preferable to use a dried product from which water has been removed.In particular, when natural mica is used, it is necessary to use a dried product at about 250 ° C. for 1 hour or more to remove the moisture. is there.

The above-mentioned aromatic hydrocarbon resin-modified novolak epoxy resin (I) is usually mixed with a cyanate ester-based curable resin composition (II) in an amount of 50% by weight or less, preferably 10 to 40% by weight.
% By weight, the total amount of the layered inorganic substance (III) (I) and (II) 1
If necessary, a known curing catalyst of the component (I) or (II) is added in an amount of 5 to 60 parts by weight, preferably 8 to 40 parts by weight, and the mixture is usually melt-mixed and reacted. The curing reaction is advanced so that heat can be easily removed, and the final curing temperature is 200 ° C.
After curing as described above, pulverization is performed to produce the heat-resistant resin dust of the present invention.

The curing catalyst for component (I) used if necessary includes aliphatic or aromatic amines, imidazole,
Phenol novolak resins and the like are preferable, and as the curing catalyst of the component (II), organic metal salts (including metal chelate compounds), inorganic metal salts, and organic peroxides are preferable. In particular, an organic metal salt alone or a combination system of an organic metal salt and an organic peroxide can be used.
Examples of the organic metal salt include zinc naphthenate, lead stearate, lead naphthenate, zinc octylate, tin oleate, tin octylate, dibutyltin malate, manganese naphthenate, cobalt tephthenate, iron acetylacetone, iron acetylacetone manganese, and the like. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, caprylic peroxide, acetyl peroxide, parachlorobenzoyl peroxide, di-tert-butyl-di-perphthalate, and the like. The amount of these curing catalysts used is generally in the range of a catalyst amount in a general sense, and is used, for example, in an amount of 0.01 to 5% by weight based on all resin components in the composition.

[0021]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” and “%” are based on weight unless otherwise specified. Example 1 Xylene / formaldehyde resin (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name: Nicanol H, number average molecular weight 460 to 500)
100 parts of phenol and 120 parts of phenol, and 0.1 part of paratoluenesulfonic acid as a catalyst at 130 ° C.
For 2 hours. Then, 1 part of zinc acetate dihydrate
40 parts of 37% formalin was added and reacted at 100 ° C. for 3 hours. After that, dehydrate under reduced pressure while heating.
At this point, dehydration under reduced pressure was completed to obtain a xylene resin-modified novolak phenol resin having a melting point of 80 ° C.

The xylene resin-modified novolak obtained above
100 parts of a phenol resin and 13 parts of solid sodium hydroxide were dissolved in 130 parts of water, and heated to 50 ° C. with vigorous stirring. To this, 32 parts of epichlorohydrin was stirred and mixed, and the mixture was uniformly mixed and reacted while maintaining the temperature at 80 ° C. while stirring and mixing. After completion of the reaction, excess epichlorohydrin was removed under reduced pressure, benzene was added, and pure water was further added for washing to remove water. Purification was repeated by adding and washing pure water again and removing water. Then
The benzene was distilled off under reduced pressure to obtain a xylene resin-modified novolak epoxy resin having a melting point of 90 ° C. (hereinafter referred to as “resin I”).

30 parts of a cyanate-maleimide resin (BT-2480 manufactured by Mitsubishi Gas Chemical Co., Ltd.) were melted at 110 ° C., and synthetic mica (MK-100, manufactured by Corp Chemical Co., Ltd.) was melted.
20 parts (average particle diameter 4.7 μm) were added and melt-mixed. Then, 70 parts of the resin I obtained above was melt-mixed with this mixture, 0.1 part of 2-ethyl-4-methylimidazole was added as a curing catalyst, and the mixture was stirred and mixed at 150 ° C. for 30 minutes.
Heat curing was sequentially performed at 150 ° C. for 30 minutes, 180 ° C. for 2 hours, 200 ° C. for 2 hours, and 240 ° C. for 3 hours. After cooling to room temperature, the cured product was pulverized to obtain 20 to 100 mesh resin dust (referred to as dust 1) powder.

Example 2 30 parts of a cyanate-maleimide resin (BT-2480, manufactured by Mitsubishi Gas Chemical Co., Ltd.) were melted at 110 ° C., and hexagonal boron nitride (h-BN) powder (manufactured by Kawasaki Steel Co., Ltd.) , HP average particle size
(5 to 15 μm) was added and melt-mixed. Then, after mixing 70 parts of the resin I obtained above to this mixture, 0.1 part of 2-ethyl-4-methylimidazole was added as a curing catalyst, and the mixture was stirred and mixed at 150 ° C. for 30 minutes.
30 minutes, 180 ° C for 2 hours, 200 ° C for 2 hours, 240 ° C for 3 hours
Heat curing was performed for a time. After cooling to room temperature, the cured product was pulverized to obtain 20 to 100 mesh resin dust (hereinafter referred to as dust 2) powder.

APPLICATION EXAMPLE 1 12 parts of hexamine is added to a phenol novolak resin, ground with a ball mill and uniformly mixed to form a binder resin.
(Denoted as PN). Using this PN, [dust 1 = 1
0; PN = 15; steel fiber = 25; rock wool = 20; aramid fiber = 3; barium sulfate = 17;
A molding material was prepared at a compounding ratio of [graphite = 10],
After press molding at 150 ° C. and a pressure of 250 kg / cm ² for 10 minutes, it was taken out of the mold and post-cured in an oven at 200 ° C. for 8 hours to obtain a molded product for a friction material.

Application Example 2 100 parts of cyanate-maleimide resin (BT-2480, manufactured by Mitsubishi Gas Chemical Co., Ltd., powder 100 mesh pass)
As a catalyst, 0.2 parts of iron acetylacetone and 0.3 parts of dicumyl peroxide were added and uniformly mixed with a Henschel mixer to obtain a binder resin (hereinafter, referred to as BT-248).

Using this BT-248, [Dust 2 = 10; BT
-248 = 15; Rock wool = 20; Brass fiber =
8; aramid fiber = 2; barium sulfate = 20; graphite =
5) A molding material is prepared at a compounding ratio of
After press molding at a pressure of 400 kg / cm ² for 10 minutes, it was taken out of the mold and post-cured in an oven at 230 ° C. for 8 hours to obtain a molded product for a friction material. Tables 1 and 2 show the results obtained by measuring the acetone-soluble matter and the heat loss temperature of the dust obtained in Examples 1 and 2, respectively. In addition, application example 1,
Table 3 shows the results of measuring the coefficient of friction using the molded article for a friction material obtained in 2.

[0028]

[Table 1]

[0029]

[Table 2] Measurement conditions: From room temperature to 700 ° C, heating rate 10 ° C / min, sample amount about 15mg.

[0030]

[Table 3] Table 3. Friction coefficient dust 25 ℃ 100 ℃ 150 ℃ 200 ℃ 250 ℃ 300 ℃ 350 ℃ 400 ℃ Application Example 1 1 0.47 0.46 0.45 0.45 0.44 0.43 0.43 0.42 Application Example 2 2 0.48 0.46 0.43 0.43 0.42 0.41 0.41 0.40

As can be seen from Table 3, the resin dust of the present invention maintains substantially the same friction coefficient in a wide temperature range from ordinary temperature to 400 ° C. Further, according to the comparison with the heating loss data in Table 2, it can be determined that even at a higher temperature of about 450 to 500 ° C., it has substantially the same friction coefficient, and the effect is extremely significant.

[0032]

As apparent from the detailed description of the invention and the examples, the heat-resistant resin dust of the present invention maintains a necessary and sufficient coefficient of friction from normal temperature to about 400 to 500 ° C. This is extremely significant.

Claims (5)

(57) [Claims] 1. An aromatic hydrocarbon resin-modified novolak type epoxy resin (I) is prepared by adding (a) a monofunctional or polyfunctional cyanate ester, a cyanate ester prepolymer or a prepolymer of the cyanate ester and an amine. Polymer, or the above
(a) and (b) a monofunctional or polyfunctional maleimide, a cyanate ester-based curable resin composition (II) containing the maleimide prepolymer or a prepolymer of the maleimide and an amine as a main component, and a layered Heat-resistant resin dust obtained by blending with inorganic (III) 2. The heat-resistant resin dust according to claim 1, wherein the amount of the cyanate-based curable resin composition (II) is 10 to 40% by weight. 3. The compounding amount of the layered inorganic substance (III) may be a component
The heat-resistant resin dust according to claim 1, wherein the total of (I) and (II) is 5 to 60 parts by weight based on 100 parts by weight. 4. The heat-resistant resin dust according to claim 1, wherein the layered inorganic substance (III) is synthetic mica or hexagonal boron nitride. 5. The heat-resistant resin dust according to claim 1, wherein said layered inorganic substance (III) is used as a mixture previously mixed with the component (II).