SE440389B - SET TO MAKE A GLASS FIBER CONTRIBUTING MATERIAL - Google Patents

Description

7906685-8 2 causes brake noise, heavy scratching and wear of the discs and short life of the friction material when the coating abuts a disc or drum of cast iron.

As an attempt to stabilize the coefficient of friction, at the same time as both the scratching and the wear of an adjacent drum or disc of cast iron is reduced, described in U.S. Patent 417,5070 a material composition for friction coatings, which includes carbon and / or graphite particles that modify any adverse effect as a material composition containing fiberglass may have on an abutting surface.

The main object of the present invention is to propose another ways to deal with the harmful effects of the glass fibers contained in goes into known friction materials, and it is based on that discovery that the harmful effects can mainly be reduced by the individual the glass fiber bundles are separated during the production of the friction material The method of the present invention thus comprises the known steps: mixing the ingredients consistently of a binder, friction modifier and 5-30% by weight of glass fiber so that a material mixture is obtained, transfer of material the mixture into a mold, to which a pressure is applied so that a briquette is formed, as well as curing of the briquette at a temperature and 1 under a pressure which causes the binder to harden and thereby assume one for the friction material desired shape and density, which method in particularly characterized by the fact that the mixing of the materials in the position may last until its bulk density is between 0.1 and 0.6 g / cm; so that a separation of the individual fibers threads of which the glass fiber is composed are obtained.

According to a preferred embodiment, the mixture of the materials included in the composition last for a period of time of between 5 and 20 minutes, preferably for about 10 minutes, after which the material composition has a bulk density of about 0.25 g / cm 3.

It has been found that material compositions prepared on the method described above and containing separate and evenly distributed glass fiber split fibers have a substantially uniform friction coefficient and an acceptable wear resistance within a temperature range ~ between 120 and 30 ° C.

These and other advantages of the invention will be readily apparent in studying the following description of some preferred embodiments forms, which are given by way of example only, with reference "__ __.._.._..__....__._.._,. s 7906685-8 to the accompanying drawings on which Fig. 1 is a table showing the components included in the material composition. fig Ph F.

:O fig fig fig fig hrs) the constituents for producing a friction pad according to the invention, is a diagram showing the friction in relation to the temperature for a typical asbestos-based friction material and for fiberglass-based friction materials, is a diagram showing the wear in relation to the the temperature of a typical asbestos-based friction material and for fiberglass-based friction materials, is a table that shows the friction stability, the friction line and the wear of coatings and sheets for a typical asbestos based friction material ° and for fiberglass-based friction material, is a graph showing fading and recovery for a ty- asbestos-based friction material and for fiberglass-based friction material, is a table showing a comparison of data from a down test performed with a typical asbestos-based friction material and with fiberglass-based friction materials, is a diagram showing the wear of coatings and discs ho a test vehicle with a typical asbestos-based friction material and with fiberglass-based friction materials, is a photograph that shows the effect of different mixing times on glass fibers, J is a photomicrograph, 20 times magnification, showing one fiberglass before and after mixing for 10 minutes, Fig. 10 is a graph showing the friction with respect to temperature. fiberglass-based friction materials manufactured in in accordance with the present invention, and Fig. 1 is a diagram showing the wear relative to the temperature. the temperature of fiberglass-based friction materials produced in accordance with the present invention. present should evaluate the friction material according to According to the present invention, a typical asbestos-based friction material A, defined in Fig. 1, which was characterized as a standard 7906685-8 4 standard or a standard intended to be an illustrative example of a acceptable coefficient of friction and degree of wear of brake pads for cars. Pig 1 also shows modified material compositions according to present invention.

The constituents of the composition constituting material A are was applied to brake friction material in the following manner: Asbestos fiber, zinc powder, organic modifiers (2 parts) cashew powder and 1 part rubber scrap), inorganic modifiers (barite) and dry phenolic resin in the quantities in% by weight given in Fig. 1 was mixed in the dry state for about 30 minutes, until its a homogeneous mixture is obtained. The homogeneous mixture was then introduced into a mold and compressed into briquettes. the chains were then transferred to a press where they were individually compressed. was added at a pressure of 420 kg / cm 2 to a predetermined shape and density, while raising the briquette temperature to about 135 ° C.

The temperature of 135 ° C caused the phenolic resin to float throughout the mixture and thereby formed a matrix which retained the others ingredients in a fixed position. The briquette was then transferred to a curing oven with a temperature of about 26OOC for further curing of the phenolic resin. The friction surface of the hardened briquette was then ground to a specific thickness corresponding to that of a brake lining. One some of the evidence was then tested using a sample dynamometer of Chase type, This test meant that a 2.5 cm? samples of frictional the material was pressed against it 40 times with a duration of 20 seconds drum of cast iron, which rotated at a speed of 525 rpm (64 km / h). after a friction sequence was tested at 120 ° C, 177 ° C, 232 ° C, 288 ° C, 343 ° C and 120 ° C (return). The output braking torque xid was kept controlled at 3.94 mfkg during the experiment, The results obtained with the sample dynamometer are shown in Fig. 2 showing the stationary friction wear at 120 ° C, 177 ° C, 232 ° C, 288 ° C and 343 ° C, and Fig. 3 shows the wear values at 120 ° C, 177 ° C, 232 ° C, 2 ° C and 343 ° C, The erection coefficient for composition A was measured and stated in in the form of curve 100 in Fig. 2, while at the different temperatures observed wear of the brake pads was calculated and stated in shape of curve 102 in Fig. 3. It should be noted that the degree of wear for composition A is acceptable below 177 ° C. When vehicles equipped with such brakes are repeatedly braked, however, the temperature rises clean rapidly above 232 ° C where the degree of wear reaches an undesirable level. s 79Û6685 ~ 8 According to the standard regulations for braking performance, established by the Department of Transportation, the maximum working temperature generated when a vehicle is stopped during repeated panic attacks. braking often to 232 ° C. Asbestos-based organic friction coatings of the standard type are therefore damaged, even if they have acceptable friction coefficients, as wear increases exponentially at temp. temperatures above 177 ° C, as shown in Fig. 3.

A brake lining of composition A was adapted to the caliper and disc in a complete brake device and was installed on an inertia dynamometer. The test procedure with the inertia dynamometer is combined performance and wear in relation to temperature, with particular emphasis on friction changes in the event of an increase effect. The test procedure included the following: efficiency control before smoothing (at 48, 96 and 128 km / h with 0.4, 0.6 and 0.7G respectively deceleration) at an initial temperature of 93 ° C; 200 smooth braking (64 km / h at 3.6 m / sec at an initial temperature of the coating of 120 DEG C.); effectiveness after smoothing (at 48, 96 and 128 km / h with 0.4, 0.6 and 0.7 G deceleration respectively) followed by three fading and retrieval controls at 232 ° C, 31S ° C and 371 ° C, and a final efficiency check (at 48, 96 and 128 km / h with 0.4, 0.6 and 0.7 G deceleration).

The degree of friction and the frictional stability of composition A specified as the braking pressure required for 3 successive braking from 96 km / h at 0.7 G deceleration is shown in Fig. 4 showed the table. Wear data for coatings and discs are also included. derade.

The fading properties of composition A are shown in lines 108, 110 and 112 and the recovery characteristics are shown in lines 114, 116 Och 118 1 fig 5. ' Due to the superior friction properties and the high the breaking strength of fiberglass compared to others for friction material suitable fibrous materials it was decided that composition A would modified by substituting glass fiber and metal oxide particles, so that a glass fiber-based composition was named material B and shown in Fig. 1.

The fiberglass known in the industry as type E is by the raw materials, such as quartz sand, limestone, dolomite, clay, boric acid, calcined soda and other minor constituents parts are heated in a high temperature oven in a direct melting process for to form glass. The glass mass flows to the front bottom of the oven in 7906685-8 6 vannan. The glass is then passed through lots of holes or openings. in platinum alloy liners or nozzles so that fine threads of molten glass are formed. The threads, which can vary in number between 20 and 2000, are assembled into a thread or string, and they are attached to a drum that rotates at a speed of up to 70,000 rpm to form fiberglass. The fiberglass is treated there- after with a silane-containing agent or an adhesive, such as eg silane, to improve resin-to-fiber adhesionD Den continuous fiber is then cut into lengths that can vary between 250 and 10,000 microns.

The composition regarding material B, as shown in Fig. 1, is was mixed in the same manner as composition A and worked up a brake pad. The rum coating of composition B was inserted into the test the Chase-type dynamometer and wear tests were performed. frictional the coefficient of composition B is shown in curve 104 in Fig. 2 and the wear is shown by curve 106 in Fig. 3. According to Fig. 2, the friction is coefficient of composition B is substantially equivalent to the coefficient of friction of composition A. However, the wear is time not acceptable for a friction material, as shown in Fig. 3.

Since the coefficient of friction of composition B, according to Fig. 2, is substantially stable over a temperature of 232 ° C, it was decided find out what modifications of composition B could reduce wear »It was thus decided to remove the abrasives the metal oxide particles and replace them with particles of cashew nut powder and non-abrasive mineral particles (barite) in the mixture, thereby obtaining composition C shown in Fig. 1v The mineral fibers in composition C are made from a mixture of silicic acid, alumina, calcium oxide, magnesium oxide and other oxides. The fiber diameters can vary between 1 and 15 microns, and the fiber length can vary between 40 and 1000 microns. In the future the position of these fibers, the fiber surface was treated with a silane agent to improve resin-to-fiber adhesion.

The composition for material C was mixed and worked up. was added to disc brake pads. Wear and friction according to with the inertia dynamometer are shown in Fig. 4. The fading properties composition C is shown by curves 120, 122 and 124, while the recovery The properties are shown by curves 126, 128 and 130 in Fig. 5. friction and wear data for composition C and for composition A clearly shows that composition C is superior to position A. 7906685-8 A test vehicle was then fitted with friction pads material compositions A and C and the results thus obtained was used for further evaluation of the glass fiber composition C.

The test vehicle was a station wagon with a total weight of 2.25 tonnes. With except for smoothing, smoothing and the periods of light / hard working conditions, performance was obtained when operating only the front ones the disc brakes. The sound assessment was made during light braking (1, f- 10.5 kg / cmz brake pressure) at low speed (8-48 km / h) within a quiet area (such as an unused parking building) to get the best possible sound amplification and observation possibilities. at each sound tests, the windows were open and the radio and heating / air conditioning ring fan turned off to get a background with low interference level. the tube search results for composition C and composition A is shown in Fig. 6. The first four series of experimental results were obtained with an initial temperature of the brake lining of the ESOC before each braking. The braking was done at 16, 48 and 96 km / h with a reduced tardation of 3 or 4.5 m / sec2 according to the specification. The fifth the series of experimental results were obtained in the same way except that the initial temperature of the brake lining was 150 ° C. At the first In the search series, the effective brake pressure was measured at different speeds before the coatings were subjected to smoothing; at the other after clearing and before fading; at the third after fading at 232 ° C and at 31 ° C; eemt at the fourth after feaing at 371 ° c.

It is clear from the information in Fig. 6 that the compositions C and A have comparable friction levels at the beginning of the experiment. The however, the asbestos-free composition C has better frictional stability than the typical asbestos-based composition A, which is confirmed by the minor change in the level of friction and in the absence of one during use increased friction leading to burnout of the bromine and frictional instability.

Following the experimental series reported in Fig. 6, the the wear of coatings and discs. The wear of the right front the leg and the disc and the left front pad and the disc regarding compositions A and C are shown in lines RF and LP, respectively, in Fig. 7. At study of Fig. 7, it is clear that composition C has a wear strength which is clearly superior to that of composition A. Wear of the discs are comparable for A and C (0.0000 and 0.0025 mm respectively).

For further evaluation of the type of material composition containing fiberglass as a reinforcing component modified composition C by excluding the carbon particles and the content of phenol 7906685-8 8 resin was reduced at the same time as the amount of glass fiber and mineral fiber was increased, thereby obtaining composition D, specified in Fig. 1.

Erection and wear values for composition D, obtained with the Chase-type sample dynamometer, shown in curves 105 and 107 in Fig. 2 and Fig. 3, respectively.

Results from experiments performed with the inertia dynamometer and with respect to composition D is shown in Fig. 4.

Composition D was then worked up into a brake pad which was mounted on the test vehicle. The results of brake tests performed with the test vehicle and with respect to composition D are shown in Fig. 6. From the results shown in Fig. 6, it is clear that both with glass fiber reinforced and with cashew nut friction powder modified Compositions C and D have better frictional stability and less coating wear than composition A.

In an attempt to repeat the results for composition D According to the table in Fig. 6, different results were obtained despite the same percentage. or by weight of the ingredients of composition D specified in Fig. 1. An explanation of the different results obtained with the same material was considered to be that insignificant variations could occur at the mixing of one or the other batch of dry ingredients looks. On examination, it was observed that the bulk density of the composition varied with increasing mixing time. This change in bulk density could be attributed to the separation of the fiber strands as the glass fiber was built by.

In order to investigate the effect of the mixing time on the six fiberglass samples were taken, each with 10 g of fiberglass Eem pro- was gradually introduced into a mixer and mixed for periods varying between 1 minute and 10 minutes. After the mixture is removed The five samples were taken from the mixer and placed in piles next to it the test sample, designated XF-10, in the manner shown in the Fig. 8. As shown in Fig. 8, the glass fiber expanded through separation in almost direct proportion to the mixing time in the mixer.

To document the theory that essentially the whole bundles of fiber strands from which the glass fiber was composed were separated photomicrographs (20x), shown in Fig. 9, of the glass fiber in the sample kf-10 and the glass fiber after 10 minutes of mixing. As shown by Fig. 9, the individual fiber threads after the mixture are random distributed without any definite orientation compared to the closely kept bundles of fiberglass in the original material. 7906685-8 To determine the optimal effect of the expansion or the opening of the bundles of glass fiber fibers contained in one friction coating, a series of experiments were performed with tion D at which the mixing times were varied. In the first component sion, designated D-1, the dry ingredients were introduced into a mixer and mixed for a period of 5 minutes. After 5 minutes the composition had a bulk density of about 0.46 g / cm 3 were placed in a briquette mold and briquettes were made from tion D-1. These individual briquettes were transferred to a press and was compressed at a pressure of about 420 kg / cm 2 to a predetermined one density, while simultaneously raising the temperature to 135 DEG C. to bring the phenolic resin to flow out into the mixture and keep the others the ingredients in a fixed position. The different briquettes were placed in a curing oven with a temperature of about 260 ° C for curing pheno the resin. The briquettes of composition D-1 were ground individually brake pads of specific gravity, and when they were then tested according to the the procedure described above in connection with Composition A in the test dynamo meter of Chase type, a coefficient of friction was obtained as shown in line 130 in Fig. 10 and a wear shown in line 132 in Figs fig 11.

Then a second composition, designated D-2, was introduced into one mixer and mixed for a period of 10 minutes. After 10 minutes: composition D ~ 2 had a bulk density of about 0.25 g / cm 3. This mixed materials were processed into brake pads in the same way as composition D-1, and when tested in the Chase-type sample dynamometer a coefficient of friction is obtained as shown by line 134 in Fig. 10 and a wear shown by line 136 in Fig. 11.

A third composition, designated D-3, was introduced into a mixer and mixed for 15 minutes. After this time, composition D- a bulk density of about 0.20 g / cm 3. This mixed material is processed was applied in the same way to brake pads, and in experiments with test dynamo meter of Chase type, a coefficient of friction was obtained as shown in line 138 in Fig. 10 and a wear shown in line 140 in fig 11.

Of the experimental results obtained with compositions D-1, D ~ 2 and D-3 it appears that the coefficient of friction in friction proofs inside holding fiberglass increases when the mixing time during manufacturing process then 1i¿9er within the range 5 ~ 15 minutes.

To ensure an even distribution of the ingredients in the final brake lining it was decided that the ingredients would feed 790668548 10 mixed before the glass fiber was added to the mixture.

The friction modifiers and the phenolic resin were introduced therein. for in a mixer and premixed for 5 minutes before the fiberglass in composition D was added, and thus a composition was obtained D-4q Composition D-4 was mixed for an additional 5 minutes for expansion or separation of the fiber strands in the glass fiber. After this period (5 minutes of premixing and 5 minutes of mixing together with the glass fiber) composition D-4 had a bulk density of about 0.45 g / cm 3. After composition D-4 has been worked up into a brake and tested on the Chase-type test dynamometer, a friction was obtained. coefficient shown in line 142 of Fig. 10 and a wear shown on line 144 in FIG.

A fifth composition, designated D-5, was prepared by mixture of friction modifier and resin for 5 minutes before the glass fiber was added, and then mixing the composition for a further 10 minutes so that the total mixing time is went to 15 minutes. After 15 minutes, composition 5-5 had one bulk density of about 0.26 g / cm3. Composition D-5 was then worked up to a brake lining and tested on the Chase-type sample dynamometer.

Composition D-S had a coefficient of friction as shown by the line 146 in Fig. 10 and a wear shown by line 148 in Fig. 11 = A sixth composition, designated D-6, was prepared by mixing of the friction modifiers and the phenolic resin below 5 minutes before the fiberglass was added. The mixture was then allowed to go for another 15 minutes so that the total mixing time amounted to 20 minutes, and the mixture then had a bulk density of about 0.21 g / cm 3. Composition D-6 was then worked up into a brake pads which, when tested, reach the Chase-type test dynamometer had a coefficient of friction shown in line 150 of Fig. 10 and a wear line shown in line 152 of Fig. 110 should confirm the observations regarding the expansion of the individual fiber strands forming the glass fiber were prepared one seventh composition, designated D-7, in which a glass fiber type E 0CF405-AA-.13 "was involved instead of the original liga fiberglass OCF497-BB-_13 ". The fiberglass configuration of CCE4OS-AA-.13 "is the same as that of OCF497-BB-.13" with the exception of the silane used as an adhesive for the bundles of fiber threads. The friction modifiers and the phenolic resin in the composition D-7 was premixed for 5 minutes before adding the glass fiber, The mixture was mixed for another 15 minutes to obtain ______, _____ ___, __ ,, _, _, _, _.... ,, \ .... »..._____» in nia -_... ...._, -.__.__ _, -.._..._.___ »_ ___-_. __V ..._, ._.: _, ~ J _, ~ _ -_ ..., _.___ n_- ». - ........ .__- ln ~~ f- '-t f-f ~ - 7906685-8 11 a total mixing time of 20 minutes and to achieve a bulk density the site of the mixture of about 0.54 g / cm 3. The mixture was worked up then to a brake pad and tested by means of test dynamometer of the Chase type. Composition D-7 had a coefficient of friction shown by line 154 in Fig. 10 and a wear shown of line 156 in FIG. 11.

Another glass fiber, identified as type E OCF636 ~ DE-.13 ", was inserted instead of the glass fiber in composition D, so that one got an additional composition, designated D-8. This fiberglass has one diameter of about 6 microns. The friction modifiers and phenol the resin in composition D-8 was premixed for 5 minutes after which time the glass fiber OCF636-DE-.13 "was added and mixing continued. for another 15 minutes, so that the total mixing time every 20 minutes. Composition D-8 had after 20 minutes of mixing a bulk density of about 0.07 9 / cm3. Composition D-E was prepared separately. to a brake lining and when tested by means of test dynamo meter of Chase type, a coefficient of friction was obtained as shown in line 158 in Fig. 10 and a wear shown by line 160 in fig 11.

In order to determine the limits of the amount of glass fiber in based friction coatings, the amount of glass fiber in the composition was reduced: and was replaced with mineral fiber and the amount of cashew nut powder was increased, va when composition E was obtained, defined in Fig. 1. Composition E bl was processed for a period of about 5 minutes and then worked up brake pads. When composition E was tested by the sample dynamometer off Chase type obtained a coefficient of friction and a wear such as both were acceptable. to further confirm the discovery of which invention based, dwrs that the opening of the fiberglass bundles stabilizes the coefficient of friction of brake linings reinforced down clasfiber and provides acceptable wear, low noise and compatible hot with a disc or brake drum of cast iron, compositions were tried further in a vehicle test. A composition, designated C 0005-1, was prepared by premixing friction modifiers and phenolic resin according to composition D for 5 minutes before the glass fiber was added, and then continued to mix further 2 minutes. Composition C 0005-1 was prepared for brake linings and mounted on a vehicle. The vehicle was driven 4140 km in all kinds of traffic on roads in Detroit, Michigan. The disc brake pads were then examined The disc brake pads on the front axle of the vehicle had the following average values 7906685-8 12 for wear: left front - inner 2.41_mm and outer 1.98 mm and right front - inner 2.54 mm and outer 1.55 mm. Both the right and the the left disc had a maximum wear of 0.178 mm, which can not considered acceptable. When testing composition C GOC5-1 below road conditions were observed that noise occurred at virtually every deceleration and friction level were irregular. with the support of the past experiments with the inertia dynamometer, it was assumed that a mixed time of 2 minutes is insufficient to open the fiber bundles.

A composition, designated C 0005-2, was therefore prepared by that the friction modifiers and the phenolic resin in composition fi were mixed for 5 minutes before the glass fiber was added, after which mixing was continued for another 7 minutes. Composi- tion C 0005-2 was then worked up into brake pads which were mounted on the test vehicle. This was driven 4320 km in all kinds of traffic on the road. and in Detroit, Michigan. The Eordon's front disc brake pads were removed then for examination. The evidence turned out to have the following wear: wear of the left front lining - the inner lining 1.27 mm and the outer coating 0.86 mm; and right front linings - inner the coating 0.99 mm and the outer coating 0.81 mm. The records were essentially free from scratches and the measured wear was a maximum of 0.025 mm, which is acceptable. During the road test with composition C 0005-2 it was observed that the noise level generated during braking had decreased to a level considered acceptable. This test thus confirmed the results obtained with the inertia dynamometer to an optimal mixing time for the opening of the glass fiber in composition D is approx 10 minutes, To further clarify the effect of an even distribution of the fiber strands of the glass fiber in a composition, the fiber bundles were replaced in composition D with ground glass fiber, whereby composition F was obtained.

Composition E was mixed for 15 minutes to obtain a smooth distribution of the fiber strands in the mixture, Composition F was made into a friction material and tested by the sample dynamometer of the Chase type, Composition F had a coefficient of friction as shown of curve 109 in Fig. 2 and a wear shown by curve 111 in Fig. 3. _ to reduce the dusty conditions associated with dry mixture, latex was used instead of rubber in the dry mixture. the composition of composition D, so as to obtain a moist mixture, composition G. The latex dispersion helped to hold it together the composition of its briquettes could be formed. A sample of ,, q o vsoesssí-í-ís? the composition material of composition G was tested by means of the sample dynamometer and it had a coefficient of friction shown by the curve 113 in Fig. 2 and a slip as shown in curve 115 in fig. 3.

Claims (6)

7906685-s y,. A method of preparing a glass fiber-containing friction material, especially intended for use as a coupling and brake lining for vehicles, comprising mixing the ingredients consisting of binder, friction modifier and 5-30 wt.% Glass fiber into a material composition, transferring the mixed material composition to the composition. a mold on which pressure is applied so as to form a briquette and curing the briquette at a temperature and pressure which causes the binder to harden, whereby the friction material assumes the desired shape and density, characterized in that the mixing of the material composition is allowed to continue until the bulk density of the mixture is between 0.1 and 0.6 g / cm 3 so that a separation of the individual fiber strands of which the glass fiber is composed is obtained. 2. A method according to claim 1, characterized in that the mixing 3 of the material composition is allowed to continue until a bulk density of about 0.25 g / cm is obtained. 3. A method according to claim 1 or 2, characterized in that the mixing of the material composition is allowed to proceed for a period of 5-20 minutes. Ä. A method according to claim 3, characterized in that the mixing is allowed to last for about 10 minutes. 5. A method according to any one of claims 1-4, characterized in that the binder and the friction-modifying agents are first mixed together as dry ingredients to form a premix, after which the glass fiber is added to the mixture and mixed together so that a material composition with the desired bulk density is obtained. 6. A method according to claim 5, characterized in that the time during which the ingredients are premixed is about five minutes, while the mixing time of the total material composition is between S and 15 minutes.