JP2000329674A - Method for testing resin permeability in preliminarily molded body of power and grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select an optimum material for a molded body by a method wherein the preliminarily molded body of a power and grain is put into a molding mold so as to be heated to a thermal molding temperature, a resin is filled, pressurized and hardened, a molded body sample is taken out from the molding mold so as to be cut and the permeation distance of the resin is measured. SOLUTION: Graphite as a sample 7 is filled into a sample housing chamber 4 in a molding mold 2. Then, the sample 7 is heated by a heating heater 6, and it is heated until it reaches a prescribed temperature. Then, a phenolic resin as a resin 9 in a prescribed amount is filled into the sample housing chamber 4 in the central part, an upper punch 5 is set quickly, a prescribed load is applied from the upper part, and the phenolic resin 9 is permeated into a graphite power layer. After the phenolic resin 9 is pressurized for a prescribed time, the sample 7 is taken out from the molding mold 2 so as to be cut, and a distance at which the phenolic resin 9 is permeated into the sample 7 is measured on the basis of the resin permeated part of the sample 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing the resin permeability of a preformed body of a granular material, for example, a method of testing the resin permeability of a preformed body of a friction material. The present invention relates to a method for evaluating the affinity (compatibility) between a raw material for use and a stirred mixture thereof and a thermosetting resin as a binder, and particularly relates to a method other than a binder resin for a friction material for brakes of automobiles, railway vehicles, industrial machines, and the like. The present invention relates to a test method for evaluating an affinity (wetting property) between a friction material raw material and a mixture thereof and a thermosetting resin as a binder of the friction material, and a degree of fibrillation of heat-resistant organic fibers in the friction material raw material stirring mixture.

[0002]

2. Description of the Related Art Conventionally, in the production of friction materials for brakes of automobiles, railway vehicles, industrial machines, etc., friction materials mainly used for brakes and the like generally contain various kinds of fillers and reinforcing materials as components. Various resins are blended together with various fibers, abrasives, graphite, metal powder, and other friction modifiers as a binder for binding these materials. In a manufacturing process of a disk pad for a disk brake, which is an example of a conventionally known method of manufacturing a friction material, the disk pad is formed into a predetermined shape by a sheet metal press, degreased and primed, and an adhesive is applied. Pressure plate, fibrous base material such as heat-resistant organic fiber, inorganic fiber, and metal fiber, and powder raw materials such as inorganic / organic filler, friction modifier, and thermosetting resin binder (specifically, phenol resin) And a preformed body prepared by molding (preforming) the raw material sufficiently homogenized by stirring at room temperature under pressure (preforming), and thermoforming at a predetermined temperature and pressure in a thermoforming step. Are integrally fixed, after-cured, and finally subjected to a finishing process.

As described above, the production of a friction material comprises the steps of blending, stirring, preforming, thermoforming, heating, polishing and grooving, etc. of the friction material as described above. The affinity (wetting property, contact angle, etc.) between the friction material raw material and the phenol resin as a binder in the above is considered as a factor relating to the strength of the compact. Further, at the time of agitation performed after measuring a predetermined amount of raw materials, the degree of defibration of the aramid fiber blended for reinforcement and the affinity of the resin are also problematic.

[0004]

However, there is no method for directly evaluating these. The capillary suction time method for measuring the wettability of the powder, the Wilhelmy method, and the method for measuring the speed at which the liquid permeates the powder layer are generally known, but these can be heated. However, it is not suitable for a liquid having a high viscosity and cannot be used for evaluating wettability with a phenol resin which is solid at normal temperature.

[0005] The present invention has been made in view of such conventional problems, and is essentially composed of a friction material raw material other than a phenol resin and a mixture thereof and a phenol resin which is a binder of the friction material. An object of the present invention is to provide a resin permeability test method for evaluating affinity (wetting), which also evaluates the degree of fibrillation of aramid fibers in a raw material stirring mixture for a friction material.

The present invention has solved the above problems by the following means. (1) In a composite material to be bound by a resin, after a preform of a granular material is put in a mold and heated to a thermoforming temperature,
After filling the resin and heating and pressurizing the resin for a predetermined time, the pressurized and cured molded body sample is taken out of the mold,
A method for testing the resin permeability of a preform of a granular material, comprising cutting the sample and measuring the penetration distance of the resin in the sample.

(2) A cylindrical preform of a friction material raw material is vertically arranged in a forming die having an opening through which an upper punch can be fitted and pushed and provided with a heating means. Get in,
Next, heating was performed by a heating means until a specified temperature was reached, and thereafter, a predetermined amount of resin was filled in the hollow portion of the cylindrical preform, and a load was applied to the upper punch through the opening, and heating and pressing were performed for a predetermined time. Thereafter, a friction material sample that has been pressed and cured is removed from the mold, the sample is cut, and the penetration distance of the resin in the sample is measured.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in the production of a friction material, an affinity between a friction material material and a thermosetting resin as a binder, which occurs during the mixing and stirring and mixing steps of the friction material raw material, In order to accurately measure the degree of fibrillation of the heat-resistant organic fiber blended for reinforcement and the affinity with the resin,
Heat-melt phenolic resin, etc., which is solid at normal temperature, and evaluate the resin permeability of the friction material in the process and the stirred mixture thereof by measuring the penetration distance into the material after heating and melting. Things. In addition, the degree of opening of the heat-resistant organic fiber and the affinity of the resin are also evaluated. For this reason, it is necessary to take out and measure the resin infiltrated into the raw material for the friction material and the stirred mixture thereof, so that the molten resin after the heat and pressure permeated the mold used for heating and pressing. It is necessary to use a type in which the raw materials for the friction material and the stirred mixture thereof can be easily taken out. For example, the mold is preferably of a split type.

As the thermosetting resin binder whose permeability (affinity) can be examined in the present invention, it is suitable to use a phenol resin (including various modified phenol resins such as straight phenol resin and rubber). The present invention can be applied to other thermosetting resins such as a melamine resin and a polyimide resin. In addition, examples of the fiber base compounded for reinforcing the friction material include heat-resistant organic fibers, metal fibers, and inorganic fibers. Among these fibers, metal fibers and inorganic fibers are not particularly problematic because they can be defibrated relatively easily in a short stirring and mixing process, but the heat-resistant organic fibers having a small thickness may be flexible. It is relatively difficult to defibrate, and the degree of defibration and the affinity of the resin affect the strength of the friction material, which is a problem.

As the heat-resistant organic fibers, aromatic polyamide fibers (aramid fibers, aramid pulp), flame-resistant acrylic fibers and the like can be preferably used. Above all,
Aramid fiber can be preferably used from the advantage of high strength and high heat resistance. Suitable commercial products of aramid fiber include Kevlar (K) manufactured by DuPont.
evlar) 29, Kevlar 49 and Kevlar 149.
Kevlar is a trade name. In view of the above-mentioned events, in the present invention, a phenol resin was selected as a binder and an aramid fiber was selected as a reinforcing fiber base material, and an experiment of permeability (affinity) was performed.

The specific test conditions are as follows. The packing of the raw material for friction material or the stirred mixture thereof has an apparent density of 0.6 g / cm ³ and a porosity of 0.73.
The specified temperature of heating is 150 ° C., the predetermined amount of the solid binder filler is 10% by weight of the raw material for the friction material or the whole of the stirred mixture, and the specified load applied to the upper punch is 7.85.
Ton, surface pressure 400 kg / cm ² , pressurization time 2-10
Minutes. In this test, it should be noted that the amount of the binder used for the raw material for the friction material or the stirred mixture thereof should be small, and the conditions should be such that the binder does not penetrate all but stops halfway. preferable. This is because, in each test, if the binder penetrates all, it cannot be distinguished and cannot be measured. As the condition, or alternatively, the pressurizing time can be adjusted.

[0012]

The present invention will be described below in detail with reference to examples. However, the invention is not limited to only these implementations.

Embodiment 1 As shown in FIG. 1, as a test apparatus 1, an opening 3 in which an upper punch 5 is fitted into an upper portion and which can be moved up and down smoothly.
And a molding die 2 having a sample storage chamber 4 inside. The mold 2 has a heater 6 for heating around the mold. A sample 7 pre-formed by lightly compressing the raw materials for friction material and their stirring mixture into a hollow cylindrical shape in a sample storage chamber 4 inside the mold 2 so that the central axis of the hollow cylinder becomes vertical. Place and put. The outer diameter of the sample 7 having the hollow cylindrical shape is the same as the inner diameter of the sample storage chamber 4, and the inner diameter is the upper punch 5.
And the same outer diameter as In this test apparatus 1, the sample 7
After the heating, the heater 9 is heated, and then the resin 9 is put into the hollow portion 8 of the sample 7 as a binder, and the upper punch 5 is pressed so that the binder 8 can be pressed. Since the diameter of the opening 3 is smaller than the diameter of the sample 7, the preformed sample 7 cannot be put into the sample accommodating chamber 4, and the sample 7 that has been pressurized and cured is placed inside the molding die 2. Since it cannot be taken out of the mold, a two-part mold was used so that it could be easily taken out.

The test for resin permeability was conducted according to the following procedure. (1) Graphite A (manufactured by Company A, average particle diameter 35 μm) and graphite B (manufactured by Company B,
An average particle size of 35 μm) was filled in the sample accommodating chamber 4 so as to have a predetermined apparent density (here, 0.6 g / cm ³ , porosity 0.73). (2) Heat by the heating heater 6 of the mold 2 and maintain it until the sample (graphite) 7 reaches a specified temperature (here, 150 ° C., a temperature corresponding to the actual thermoforming temperature). (3) A predetermined amount of phenolic resin (novolak-type phenolic resin / hexamethylenediamine (curing agent)) (here, 10% by weight of the sample) is filled as the resin 9 in the sample accommodating chamber 4 at the center, and the upper punch 5 is quickly filled. Is set, a specified load (7.85 ton, surface pressure: 400 kg / cm ^{2 in this case} ) is applied from above, and the phenol resin 9 is permeated into the graphite powder layer 10. (4) After pressurizing for a predetermined time (here, 10 minutes), the sample 7 is taken out of the mold 2 and cut, and the distance 11 from which the resin 9 has penetrated into the sample 7 from the resin permeated portion 10 of the sample 7 is measured.

(5) Table 1 shows the measurement results. From the measurement results, it was confirmed that graphite A had better affinity with the phenol resin than graphite B. Graphite A is amorphous graphite, and graphite B is crystalline graphite.

[0016]

[Table 1]

Example 2 Instead of the graphite of the above (1) of Example 1, a mixture of the raw materials for a friction material (containing no phenol resin) in the mixing ratio shown in the following Table 2 was stirred for 2 minutes. (C),
The same test procedure as in Example 1 was repeated, except that the mixture (D) for 6 minutes was used. The measurement results are shown in Table 3 below. From the measurement results shown in Table 3, the longer the stirring time, the more sufficiently the reinforcing aramid fiber was defibrated, and as a result, the affinity (wetting property) between the raw material mixture for friction material and the phenol resin was improved, and the friction material was improved. It is presumed that the strength of the steel is also improved.

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

According to the present invention, by using a mold which can be heated and pressurized and can easily take out a heated and cured friction material sample, the friction material which cannot be obtained by the conventional method can be obtained. As a result of being able to measure the affinity between the raw materials and the stirred mixture thereof and the resin, it became easy to select the material for obtaining the optimum molded product. In addition, the degree of agitation of the agitated mixture of the raw materials for the friction material which affects the physical properties of the molded brake pad (particularly, the degree of fibrillation of aramid fibers) can be measured and specified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a test apparatus used for a resin permeability test method of the present invention.

FIG. 2 shows a plan view of a test apparatus used for the resin permeability test method of the present invention.

FIG. 3 is a sectional view showing the results of a penetration test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Test apparatus 2 Mold 3 Opening 4 Sample accommodating chamber 5 Upper punch 6 Heater 7 Sample (graphite or stirring mixture) 8 Hollow part 9 Resin 10 Resin penetration part 11 Penetration distance

Claims (2)

[Claims] In a composite material bound by a resin, a preform of a granular material is put into a mold, heated to a thermoforming temperature, filled with a resin, and heated and pressed for a predetermined time. Thereafter, the pressed and cured molded product sample is taken out of the mold, the sample is cut, and the penetration distance of the resin in the sample is measured. Test method. 2. A cylindrical preform of a friction material raw material is vertically placed in a forming die having an opening through which an upper punch can be inserted and pushed and provided with a heating means. Then, heating is performed by a heating means until a predetermined temperature is reached, and thereafter, a predetermined amount of resin is filled in the hollow portion of the cylindrical preform, and a load is applied to the upper punch through the opening, and heating and pressing are performed for a predetermined time. A method for testing the permeability of a friction material material to a resin, comprising taking out a pressed and cured friction material sample from a mold, cutting the sample, and measuring a penetration distance of a resin in the sample.