JP2005097374A - Phenol resin composition for friction material, its manufacturing method, mixture for friction material and friction material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin composition for a friction material capable of making the friction material superior in vibration absorptive properties without reduction of mechanical strength and its manufacturing method, and a mixture for the friction material using the phenol resin composition, which are performed as a result of various studies to solve problems found in a conventional phenol resin composition for the friction material and a conventional friction material. <P>SOLUTION: This phenol resin composition for the friction material comprises a phenol resin and mica, in which they are dispersed and mixed. The manufacturing method of the phenol resin composition has a step of dispersing and mixing the phenol resin and the mica. The mixture for the friction material using the phenol resin composition and the friction material are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

Phenolic resins have excellent heat resistance and adhesiveness, and are widely used as binders for friction materials incorporated in automobiles. In recent years, with the improvement in performance and quality of automobiles, the quietness of automobiles has improved, and therefore, faint squeaking and abnormal noise generated from friction materials have become a problem.
In order to improve such problems, research on modified phenolic resins as a binder for friction materials has been actively conducted. Oil-modified phenolic resins, cashew-modified phenolic resins, silicone-modified phenolic resins, and various rubber-modified phenolic resins include It is being considered. By using these modified phenolic resins, the hardness of the friction material is reduced, the vibration absorption is improved, the generation of noise and abnormal noise has been suppressed, on the other hand, the heat resistance of the friction material is reduced, There is a problem that the formability at the time of manufacturing the friction material deteriorates, and it cannot be said that the characteristics are sufficient.

In addition to the above-mentioned method using modified phenolic resin, flaky inorganic material and cashew dust are blended as an additive together with a fiber base material and binder, reducing noise and abnormal noise, and improving heat resistance and moldability Is disclosed (for example, see Patent Document 1).
However, according to such a method, since the friction material is manufactured by molding a fiber base material, a binder, and the above-mentioned additive in a lump, the friction material is manifested by the adjoining scale-like inorganic substance and the binder. The effect of absorbing vibration is not fully exhibited.

JP-A-06-009994

  The present invention has been completed as a result of various studies in order to solve the problems of conventional phenolic resin compositions for friction materials and friction materials, and has excellent vibration absorption without reducing mechanical strength. The present invention provides a phenol resin composition for a friction material and a method for producing the same, and a friction material mixture and the friction material using the phenol resin composition for a friction material.

Such an object is achieved by the following present inventions (1) to (12).
(1) A phenol resin composition for a friction material, comprising a phenol resin and mica, wherein the phenol resin and the mica are dispersed and mixed.
(2) The friction according to (1), wherein the mica is selected from mascobite (muscovite), phlogopite (phlogopite), biotite (biotite), and fluorine phlogopite (artificial mica). Phenolic resin composition for materials.
(3) The said mica is a phenol resin composition for friction materials as described in said (1) or (2) whose weight average flake diameter is 5-2000 micrometers.
(4) The phenolic resin composition for a friction material according to any one of (1) to (3), wherein the mica has a weight average aspect ratio (ratio of weight average flake diameter to average thickness) of 10 to 200. .
(5) The phenol resin composition for friction materials according to any one of (1) to (4), wherein the phenol resin composition for friction materials contains 2 to 60% by weight of the mica.
(6) The method for producing a phenol resin composition for a friction material according to any one of (1) to (5), comprising a step of dispersing and mixing the phenol resin and the mica. The manufacturing method of the phenol resin composition for friction materials.
(7) The method for producing a phenol resin composition for a friction material according to the above (6), comprising a step of adding and mixing the mica before, during or after the reaction of the phenol resin.
(8) The manufacturing method of the phenol resin composition for friction materials as described in said (6) which has a process which melt | dissolves the said phenol resin or dissolves in a solvent, and mixes with the said mica.
(9) The method for producing a phenol resin composition for a friction material according to the above (6), comprising a step of adding and mixing the mica when the phenol resin is pulverized.
(10) A friction material mixture obtained by blending the friction material phenol resin composition according to any one of (1) to (5) above.
(11) A friction material mixture obtained by blending the phenol resin composition for a friction material obtained by the production method according to any one of (6) to (9) above.
(12) A friction material formed by molding the friction material mixture according to (11) or (12).

The present invention is a phenol resin composition for a friction material, comprising a phenol resin and mica, wherein the phenol resin and mica are dispersed and mixed.
Further, the present invention is a method for producing a phenol resin composition for a friction material, characterized by having a step of dispersing and mixing a phenol resin and mica. It is suitable as a method for producing the above.
Then, by molding a friction material mixture containing such a friction material phenol resin composition, a friction material having excellent vibration absorption can be obtained without reducing mechanical strength.

Hereinafter, the phenol resin composition for a friction material of the present invention and the production method thereof, and the mixture for friction material and the friction material using the phenol resin composition for friction material will be described.
The phenol resin composition for a friction material of the present invention (hereinafter sometimes simply referred to as “composition”) contains a phenol resin and mica, and the phenol resin and mica are dispersed and mixed. It is characterized by that.
The method for producing a phenol resin composition for a friction material of the present invention (hereinafter sometimes simply referred to as “manufacturing method”) is a method for producing the composition of the present invention, wherein the phenol resin and mica are dispersed and mixed. It has the process to make it feature.
The friction material mixture of the present invention is obtained by blending the composition of the present invention or the composition obtained by the production method of the present invention.
The friction material of the present invention is obtained by molding the friction material mixture of the present invention.
First, the composition of the present invention will be described in detail.

Although it does not specifically limit as a phenol resin used for the composition of this invention, For example, a resol type phenol resin, a novolak type phenol resin, etc. are mentioned. Among these, a novolac type phenol resin is often used for the friction material.
The method for synthesizing the above novolak type phenol resin is not particularly limited, but usually, phenols and aldehydes are reacted with phenols (P) in the presence of an acidic catalyst such as oxalic acid, hydrochloric acid, sulfuric acid, toluenesulfonic acid and the like. It can be obtained by reacting the aldehydes (F) at a molar ratio (F / P) of 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, aldehydes are not particularly limited. For example, aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, or a mixture thereof, and substances that generate these aldehydes or these aldehydes. In general, 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 solid powder can be used.
This novolac type phenol resin can be appropriately selected and used in an optimum form according to the method for producing the composition of the present invention. For example, when a phenol resin and mica are pulverized and mixed, a solid or solid powder can be used. Moreover, when mixing with a mica in the reaction process of a phenol resin, or melt | dissolving or dissolving a phenol resin in a solvent and mixing with a mica, the thing of any said form can be used.

In addition, in the composition of this invention, when using a novolak-type phenol resin as a phenol resin, hexamethylene tetramine can be normally mix | blended as a hardening | curing agent.
The blending amount of hexamethylenetetramine is not particularly limited, but is preferably 3 to 20 parts by weight, more preferably 7 to 17 parts by weight with respect to 100 parts by weight of the novolac type phenol resin. When the amount of hexamethylenetetramine is less than the above lower limit, curing of the novolac type phenol resin may be insufficient. When the above upper limit is exceeded, the gas generated by the decomposition of hexamethylenetetramine may cause blisters and cracks in the friction material that is a molded product.

The mica used in the composition of the present invention is generally classified as a mica mineral, and the shape thereof is usually a flake shape.
Although it does not specifically limit as a kind of mica used in the composition of this invention, For example, from mascobite (muscovite), phlogopite (phlogopite), biotite (biotite), and fluorine phlogopite (artificial mica) What is selected can be used. Moreover, these may be used individually by 1 type and can also use 2 or more types together.

  The mica used in the composition of the present invention forms a layer structure, and has a property of being easily peeled off between the layers. For this reason, when the composition of the present invention containing a phenol resin and mica is used as a friction material, and stress acts in the layer direction of mica, shear stress is generated in the phenol resin layer existing between mica particles. . Thereby, the loss elastic modulus of the friction material using the composition of this invention increases, and the vibrational absorption effect can be expressed.

The particle diameter of the mica is not particularly limited, but the weight average flake diameter is preferably 5 to 2000 μm, and particularly preferably 5 to 500 μm.
When the weight average flake diameter exceeds the above upper limit, the mixing accuracy with the phenol resin decreases, and when the weight average flake diameter is less than the lower limit, the vibration absorption effect may not be sufficiently exhibited.

The weight average aspect ratio of the mica used in the composition of the present invention (ratio of the weight average flake diameter to the average thickness) is not particularly limited, but is preferably 10 to 200.
When the aspect ratio exceeds the above upper limit, the accuracy of mixing with the phenol resin decreases as in the case where the flake diameter is excessive, and when it is less than the above lower limit, the vibration absorption effect may be poor. .

Although the compounding quantity of the mica in the composition of this invention is not specifically limited, It is preferable that it is 2 to 60 weight% with respect to the whole composition. Particularly preferably, it is 10 to 50% by weight.
If the blending amount of mica is less than the lower limit, depending on the blending amount in the friction material mixture, a sufficient vibration absorbing effect may not be obtained for the friction material. If the upper limit is exceeded, the amount of the phenolic resin as a binder decreases, so that the mechanical strength when used as a friction material may be lowered depending on the blending amount in the friction material mixture.

Next, the manufacturing method of this invention is demonstrated.
The production method of the present invention is a method for producing the above-described composition of the present invention, and includes a step of dispersing and mixing a phenol resin and mica.

The method for dispersing and mixing the phenol resin and mica is not particularly limited. For example, the following methods (a) to (c) can be applied.
(A) Mica is added and mixed before, during, or after the reaction of the phenol resin.
(A) A phenol resin is melted or dissolved in a solvent and mixed with mica.
(C) When the phenol resin is pulverized, mica is added and mixed.

Specifically, in the method of (a), in the phenol resin synthesis reaction step, before or during the reaction, mica is added and mixed to perform the phenol resin synthesis reaction. Or a method of obtaining a mixture of a phenol resin and mica by adding and mixing mica to a phenol resin after reaction (usually in a state having fluidity before cooling).
Among these, the method in which mica is added to and mixed with the phenol resin after the reaction is a preferable mode because the viscosity of the reaction system does not increase during the synthesis reaction of the phenol resin.
When the obtained mixture is taken out from the reaction apparatus and solid after cooling, a mixture obtained by pulverizing the mixture into an appropriate particle size can be used as the composition of the present invention.

In the method (a), a phenol resin that has been removed from the reaction apparatus after completion of the reaction is usually used.
As a method of melting the phenol resin and mixing with mica, for example, after the reaction is finished, the cooled and solidified phenol resin is pulverized to an appropriate particle size under pressure using a pressure kneader together with mica. The method of kneading is mentioned. When kneading, mica can be mixed in the phenolic resin phase in a molten state by performing at a temperature at which the phenolic resin melts.
Although it does not specifically limit as a pressure-type kneading apparatus used here, For example, a roll-type kneader, a pressure kneader, a twin screw extruder, a single screw extruder etc. can be used.
When the molten mixture thus obtained is solid, a mixture obtained by pulverizing it to an appropriate particle size can be used as the composition of the present invention.

Moreover, as a method of dissolving the phenol resin and mixing with mica, for example, the phenol resin is dissolved in an organic solvent or melted in a solvent, and then the mica is added thereto and mixed with a dispersion mixer, and then the solvent used. The method of removing is mentioned.
The dispersion and mixing apparatus used here is not particularly limited, but a normal stirring apparatus, homomixer, disperser, bead mill, T.W. K. Examples thereof include a high-speed stirring device such as Filmix (manufactured by Special Machine Industries Co., Ltd.), a high-pressure impingement device such as a high-pressure homogenizer, or an ultrasonic stirring device. These dispersion mixing apparatuses can be appropriately selected and used depending on the viscosity of the phenol resin solution, the properties of the mica to be mixed and the blending amount.
If the mixture thus obtained is solid after removing the solvent, it can be used as the composition of the present invention if it is ground to an appropriate particle size.

In the method (c), a solid phenol resin taken out from the reaction apparatus after completion of the synthesis reaction is usually used. When this phenolic resin is pulverized to an appropriate particle size, by adding and mixing mica,
A composition in which a phenol resin and mica are mixed with high accuracy can be obtained, and a form in which the phenol resin and mica are partially combined by energy such as collision, shear, friction given at the time of pulverization and mixing. can do.
Here, it does not specifically limit as an apparatus used for the grinding | pulverization of a phenol resin, A well-known grinding | pulverization apparatus can be used.
The mixture thus obtained can usually be used as it is as the composition of the present invention.

  In addition, when mixing a phenol resin and mica, or when pulverizing a mixture of a phenol resin and mica, if necessary, for example, hexamethylenetetramine is added to perform hexamethylenetetramine. Can also be obtained.

  Examples of the method for dispersing and mixing the phenol resin and mica include the above-described forms. At this time, depending on the type and operating conditions of the apparatus used, high energy acts on the mixture of the phenol resin and mica, Since pulverization of mica particles may occur, it is preferable to appropriately adjust conditions and the like so that the mica particles can maintain the above-mentioned particle size and shape.

  By the method as described above, the composition of the present invention in which the phenol resin and mica are dispersed and mixed can be obtained. By using the composition thus obtained for the friction material, the following effects can be obtained.

In the conventional manufacturing method, the friction material mixture used for the friction material is blended with a binder such as phenol resin, a fiber base material such as aramid fiber, and an inorganic filler at the same time, and a dry mixing device or the like is prepared. And obtained by batch mixing.
However, when phenolic resin and mica are mixed together with other materials by such a manufacturing method, these components are unevenly distributed in the friction material mixture, resulting in insufficient dispersibility and insufficient mixing accuracy. There is. This is probably because the mixing energy given at the time of manufacturing the friction material mixture is usually not so large, and phenol resin and mica are relatively small in the friction material mixture. .
In the case of a friction material using such a friction material mixture, the loss elastic modulus of the friction material increases and absorbs vibration due to the shear stress generated in the phenol resin layer existing between the mica particles in the friction material. It is thought that it will be difficult to fully exhibit the effect of this.

On the other hand, since the composition of the present invention uses a resin in which a phenol resin and mica are preliminarily dispersed and mixed by the above-described method, the phenol before the friction material mixture is produced. The resin and mica are already mixed with high accuracy, and a part of the resin is considered to be in a composite form.
In this way, the phenol resin and mica are dispersed and mixed in advance, and this is mixed with other materials to produce a friction material mixture. Can be improved. And even when this friction material mixture is used as a friction material, the above-described shear stress can be effectively expressed, and the vibration absorption effect of the friction material can be further enhanced.

Next, the friction material mixture of the present invention will be described.
The friction material mixture of the present invention is obtained by blending the composition of the present invention or the composition obtained by the production method of the present invention.
In the friction material mixture of the present invention, the components other than the composition of the present invention or the composition obtained by the production method of the present invention are not particularly limited. For example, inorganic materials other than base fibers and mica Examples include fillers. Although it does not specifically limit as base fiber here, For example, heat resistant fibers, such as an aramid fiber, a Kevlar fiber, and a glass fiber, can be used conveniently. Moreover, it is although it does not specifically limit as inorganic fillers other than mica, For example, a calcium carbonate, barium sulfate, etc. can be used conveniently.
The blending amount of these components is not particularly limited, and the blending amount can be appropriately adjusted in accordance with the properties and required characteristics of the target friction material. For example, the composition 10 of the present invention 10 -20% by weight, base fiber 5-10% by weight, and inorganic fillers 70-85% other than mica can be blended to form a friction material mixture.

Next, the friction material of the present invention will be described.
The friction material of the present invention is obtained by molding the above-described mixture for friction material of the present invention with a predetermined mold, and can be obtained by further firing the obtained molded product as necessary.
In the case of molding, optimum conditions can be appropriately selected depending on the composition of the friction material mixture. For example, the temperature is 140 to 180 ° C., the pressure is 100 to 300 kg / cm ² , and the time is 3 to 20 minutes. Can be molded. Moreover, it is although it does not specifically limit as conditions for baking the obtained molded article, For example, it can bake at 170-300 degreeC for 3 to 15 hours. Thus, the friction material of the present invention can be manufactured.

  Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to these examples. In the examples and comparative examples, “part” indicates “part by weight” and “%” indicates “% by weight”.

1. Production Example 1 of Composition
To a twin screw extruder controlled at an inlet temperature of 150 ° C. and an outlet temperature of 160 ° C., 1000 parts of a novolak type phenolic resin (“PR-53195” manufactured by Sumitomo Bakelite Co., Ltd.), mica A (manufactured by Kuraray Co., Ltd., “Kuralite Mica 400” -D ", 300 parts of a weight average particle diameter of 18 μm and a weight average aspect ratio of 30) were supplied so that the supply ratio per unit time was equal, and 1290 parts of a phenol resin mixture solid at room temperature was obtained from the outlet.
To 1000 parts of the obtained mixture, 110 parts of hexamethylenetetramine was added and pulverized and mixed to obtain 1090 parts of a powder composition.

Example 2
A pressure kneader was charged with 1000 parts of a novolac-type phenolic resin (“PR-53195” manufactured by Sumitomo Bakelite Co., Ltd.), heated to 150 ° C. and melted. Add 1000 parts of Mica B (Kuraray Co., Ltd., “Kuralite Mica 500-D”, weight average particle size 10 μm, weight average aspect ratio 20), confirm that mica is uniformly dispersed, and knead for 30 minutes. And 1950 parts of a phenol resin mixture which was taken out from the pressure kneader and solid at room temperature was obtained.
To 1000 parts of the obtained mixture, 55 parts of hexamethylenetetramine was added and ground and mixed to obtain 1040 parts of a powder composition.

Example 3
A reaction apparatus equipped with a stirrer, a reflux condenser and a thermometer was charged with 1000 parts of a novolac-type phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., “PR-53195”) and 1000 parts of methanol, and the mixture was heated to 80 ° C. and melted. 100 parts of mica C (“Kuraray Mica 60-C” manufactured by Kuraray Co., Ltd., weight average particle size 340 μm, weight average aspect ratio 80) was added thereto, and the mixture was stirred for 1 hour. Solvent was obtained, and 1030 parts of a phenol resin mixture solid at room temperature was obtained.
To 1000 parts of the obtained mixture, 110 parts of hexamethylenetetramine was added and pulverized and mixed to obtain 1090 parts of a powder composition.

Example 4
110 parts of hexamethylenetetramine and 1000 parts of mica A were added to 1000 parts of a novolak type phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., “PR-53195”), and pulverized and mixed to obtain 2100 parts of a powder composition.

Example 5
In Example 1, 1140 parts of a phenol resin mixture solid at room temperature was obtained in the same manner as in Example 1 except that the amount of mica A was 150 parts.
To 1000 parts of the obtained mixture, 110 parts of hexamethylenetetramine was added and pulverized and mixed to obtain 1090 parts of a powder composition.

Comparative Example 1
110 parts of hexamethylenetetramine was added to 1000 parts of a novolak-type phenol resin (Sumitomo Bakelite Co., Ltd., “PR-53195”), and pulverized and mixed to obtain 1090 parts of a powder composition.

2. Preparation of friction material mixture Six kinds of compositions obtained in Examples 1 to 5 and Comparative Example 1, aramid fibers as fiber base materials, and calcium carbonate and barium sulfate as inorganic fillers are shown in Table 1. A mixture for a friction material was prepared by mixing at the blending ratio shown. For Comparative Example 1, mica was mixed at this time.

3. Preparation of friction material The friction material mixture obtained above was molded at a temperature of 160 ° C. and a pressure of 200 kg / cm ² for 10 minutes to obtain a molded product of 100 × 100 × 15 mm. The obtained molded product was further baked at 200 ° C. for 5 hours to produce a friction material.

Table note: Materials used
(1) Aramid fiber: Dry pulp Fiber length 2mm
(2) Calcium carbonate: Average particle size 20 μm
(3) Barium sulfate: average particle size 20 μm

3. Evaluation of friction material The friction material produced by the above method was used as an evaluation sample, and the following evaluation was performed. The results are shown in Table 2.

Note to table: Evaluation method
(1) Normal bending strength: Measured according to JIS K 7203 “Bending test method of hard plastic”.
(2) Dynamic viscoelasticity: Tan δ was measured with a viscoelasticity measuring device “DMS6100 type” manufactured by Seiko Instruments Inc. The measurement conditions were a measurement temperature of 30 to 300 ° C. and a frequency of 100 Hz, and the values of tan δ at 50 ° C., 150 ° C., and 250 ° C. were compared.

Each of Examples 1 to 5 is a composition of the present invention containing a phenol resin and mica, and in which the phenol resin and mica are dispersed and mixed.
As a result of evaluating the friction material obtained by molding the friction material mixture containing these compositions, a resin composition containing no mica was used, and compared with Comparative Example 1 in which mica was added at the time of producing the friction material. In particular, while having the same normal bending strength, the value of tan δ at each evaluation temperature was high, and the vibration absorption was excellent.

  The present invention is a phenol resin composition for a friction material capable of obtaining a friction material excellent in vibration absorption without reducing mechanical strength, and a friction formed by molding a mixture for friction material containing the friction material. The material is suitably used, for example, as a friction material for automobiles that require high performance and high quality.

Claims (12)

A phenol resin composition for a friction material, comprising a phenol resin and mica, wherein the phenol resin and the mica are dispersed and mixed. 2. The phenol resin for a friction material according to claim 1, wherein the mica is selected from mascobite (muscovite), phlogopite (phlogopite), biotite (biotite), and fluorine phlogopite (artificial mica). Composition. The phenolic resin composition for a friction material according to claim 1 or 2, wherein the mica has a weight average flake diameter of 5 to 2000 µm. 4. The phenol resin composition for a friction material according to claim 1, wherein the mica has a weight average aspect ratio (ratio of a weight average flake diameter and an average thickness) of 10 to 200. 5. The phenol resin composition for friction materials according to any one of claims 1 to 4, comprising 2 to 60% by weight of the mica based on the entire phenol resin composition for friction materials. 6. The method for producing a phenol resin composition for a friction material according to claim 1, further comprising a step of dispersing and mixing the phenol resin and the mica. Manufacturing method. The method for producing a phenol resin composition for a friction material according to claim 6, further comprising a step of adding and mixing the mica before, during, or after the reaction of the phenol resin. The manufacturing method of the phenol resin composition for friction materials of Claim 6 which has a process which melt | dissolves the said phenol resin or dissolves it in a solvent, and mixes with the said mica. The manufacturing method of the phenol resin composition for friction materials of Claim 6 which has the process of adding and mixing the said mica when grind | pulverizing the said phenol resin. A friction material mixture obtained by blending the phenol resin composition for a friction material according to any one of claims 1 to 5. A friction material mixture obtained by blending the phenol resin composition for a friction material obtained by the production method according to claim 6. The friction material formed by shape | molding the mixture for friction materials of Claim 11 or 12.