CA1061039A - Antifriction polymer material - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An antifriction polymer material which is a product of hardening of a composition consisting of a filler in amounts of 10-95 wt. % and a binder in amounts of 5-90 wt.%, a mixture of polyphenylenes being used as a binder containing ketal and/or acetyl groups of the general formula , where n = 2 - 500, , , , , , , where m = 1-4;

R3 and R4 + ,

Description

.

The present invention relates toantifriction polymer materials.
These antifriction polymer materials combine the properties of solid lubricants and construction materials. They are used for manufacturing articles, for example, separators for antifriction bearings, linings for sliding bearings, and various components of gear drives operating in dry friction units.
Antifriction ~olymer materials assure a low friction coefficient without commonly employed liquid or lubricants or greases.
These materials operate under conditions where the application of liquid lubricants is impossible or not permissible:
various electrical vacuum devices, cinema projectors, components of irradiation devices, bearings operating at high temperatures and under outer space conditions, etc., need antifriction polymer materials.
Polymer antifriction materials are products result-ing from the hardening of compositions which are multicomponent systems, consisting of a binder and a filler. As a binder use is made of polymers with required properties, primarily, thermal and heat resistance, resistance to irradiation, chemical stability, and which are easily workable. Commonly used solid lubricants such as graphite, molybdenum disulphide, boron nitride, etc., are employed as fillers of antifriction polymer materials. To strengthen a composition, fibrous fillers may also be introduced: fibre glass, asbestos, graphitized fibres, carbon fibres and the like. Metallic powders of molybdenum, nickel, copper and other metals are added to a filler for improving heat and electroconductivity, mouldability, and increasing hardness of the antifriction polymer material.

-1- ~

The fillers are introduced into the composition of the antifriction polymer material either separately or in combination.
The binder and filler conten~s in the antifriction polymer material may vary greatly, their optimum amounts being determined to suit the requirements imposed on the properties of the articles.
An antifriction polymer material which is a product of hardening a composition consisting of a ~inder and a filler is known in the art. In this pxior art material polyphenylenes with ethynyl groups, obtained by polycyclotrimerization of di-and monoethynyl compounds, are used as a binder. In the course of the reaction a benzene ring is formed from three ethynyl groups substituted in positions 1, 3, 5 or 1, 2, 4. The composition consisting of said binder and filler is subjected to hardening in closed type press moulds at a temperature from 130-450C under a pressure ensuring solidity of the articles (from 7 to 1,000 kg/cm ).
One of the principal disadvantages inherent in anti-friction polymer materials produced from known compositions istheir low wear resistance due to a decrease in their thermal resistance at temperatures about 300C. Therefore, using these materials in dry friction units at temperatures exceeding 300C
presents difficulties.
The object of the present invention is to provide an antifriction polymer material which will possess high thermal resistance ensuring sufficiently good antifriction properties at temperatures about 300C.
In accordance with this and other objects of the invention, there is provided an antifriction polymer material which is a product resulting from the hardening of a composition "

10~039 consisting of a filler and a binder, viz., a mixture of polyphenylenes. According to the invention the binder compris~s polyphenylenes containing ketal and/or acetyl groups of the general formula R3 - ~ ~ Rl ~ R4

2 , where n = 2 - 500, ~= ~ ~ ~ ~ CH2 ~ , ~ , 2 ~ , ~ (CH2)m - CH3 , where m = 1-4;

R3 and R4 = - C \ - C -CH3 R3 and R4 being identical or different, the content of the filler amounting to 10-95 wt. %, the content of the binder, to 5-90 wt.% , the fraction with n = 2-15 being 4-20% of the weight of the binder.
In addition to the main fraction with n = 10-500, a fraction with n = 2-15 (low molecular fraction) must also be present.
The binder of such a composition permeates the filler well and on hardening (moulding) it formsarticles of high thermal stability.
This is due to the fact that the low molecular fraction of polyphenylenes has a large number of reactive groups and during moulding it serves as a hardener of the high molecular fraction. These polyphenylenes are obtained by the polycyclocon-1()61039 densation of di- and monoacetyl compounds or their ketals.
In the course of the reaction a benzyl ring is formed from three acetyl or ketal groups subs-tituted only in positions 1, 3 and 5.
A composition consisting of a binder and fillers is hardened in closed type press moulds at a temperature of 300-500C under a pressure of 50-1000 kg/cm2.
The ratio of a polymer binder and fillers in the antifriction polymer material varies greatly and is determined lQ by require;ments imposed upon the article to be manufactured from this material. According to the invention the antifriction polymer material contains 5-90 wt.% of polyphenylene and 10-95 wt.% of fillers.
As fillers the antifriction polymer material may contain substances of mineral or artificial origin, at least one of which possesses antifriction properties. They are so-called "solid lubricants" and their co-geners, the main representatives being: molybdenum disulphide, graphite, boron nitride, tungsten disulphide, tungsten diselenide, talc. Their content in the antifriction polymer material varies from 3 to 79%.
Besides the above-cited group of fillers, the proposed antifriction material mày also contain fillers selected from the group consisting of strengthening agents: e.g. carbon fibres and graphitized fibres in amounts of 20-90O/~ of the weight of the material; from the group consisting of metallic powders:
e.g. powders of copper, nickel and silver in amounts of 10-30%
of the weight of the material; as well as from the group consist-ing of additives capable of controlling the friction: e.g.
quartz powder and asbestos in amounts from 0.5 to 5 wt.% of the material weight. Introduction of large amounts of solid lubri-cants as fillers (molybdenum disulphide, graphite, etc.) reduces the friction coefficient and yields self-lubricating materials.
When high-strength antifriction materials are required, the content of a polymer binder in them may be increased up to 90 wt.%.
The proposed antifriction material based on a mixture of polyphenylenes possesses high heat resistance (about 350C) and thermal stability (about 450C), which ensures a stable friction coefficient and high wear resistance at temperatures up to 320C (linear wear intensity of about lxlO 8).
The antifriction polymer material is produced in the following manner.
The starting polyphenylenes having ketal and/or acetyl groups can be obtained by polycyclocondensation of di-and monoacetyl compounds or their ketals. The formula of a difunctional derivative may be represented as follows:

3 1 R4 wherein ~ ~ ~ ~3CH2~

~30~3 ~ ~OC2H5 R2 and R4 = - C ~ C - CH3 CH3 , 2H5 A monofunctional derivative may be represented by .he formula:

X~Y
, where .. }" , .. . . . . ...

X = -H; -CH3, (C~2)m-CH3, in which m = 1-4, or is absent, D /C2H~
Y = - C : - C ~ CH

The molar ratio of di- and monofunctional derivatives is chosen from the range 1:1-1.5, respectively, the optimum molar ratio being -1:1 for producing less branched soluble polyphenylenes.
Polycyclocondensation proceeds in dry benzene at 10-30C in the presence of a catalyst, namely, gaseous hydrogen chloride: in the case of acetal compounds a ketalization agent is also present, viZo ~ ethylorthoformate (triethyl) ester of orthoformic acid, HC (OC2H5)3 . The reaction duration depends on the ratio between the starting di- and monofunctional compounds and the rate of passing gaseous hydrogen chloride;
it varies from 0.3 to 80 hrs.
To obtain the starting polyphenylenes, selected ratios of mono- and diacetyl compounds or their ketals are put into a four-necked flask fitted with a stirrer, thermometer5 and a capillary tube for introducing and leading out the catalyst, viz., gaseous hydrogen chloride. Then dry benzene is added to bring the concentration of the functional groups to 1 gr eqv~l. The flask is thermostated at a chosen temperature (10-30C). In the course of the reaction, the reaction mass turns from colorless to dark cherry. On completion of the reactionj the reaction mixture containing the desired product is poured into ethyl, methyl, or propyl alcohol. The precipitated product is filtered on a filter, washed with an alcohol, a water alkaline solution, and water until the reaction mixture becomes neutral. The powder is dried in a vacuum drying cabinet at 60~C. The melting point of the polyphenylene mixture obtained ,, ~ i . . ~, is within the range of 100-200C.
In the course of the reaction a trisubstituted benzene ring is formed according to the scheme presented below from three acetyl or ketal groups in positions 1, 3,5.

~3 ~OC2H5 ~3cD

\ H~ H+ ~

2 5 ~ ~ ( 2 5)3 ,ll~, The resulting mixture of polyphenylenes, which is used as a binder for preparing the polymer antifriction material is mixed with fillers in definite weight ratios.
To ensure proper homogenation of the composition (dispersity of no more than 0.1 mm), the mixture of polyphenyl-enes is blended with fillers on vibration mills. As a resultof mixing, a pulverulent moulding composition is produced.
The moulding composition obtained is processed on a standard equipment for processing plastics by compression mould-ing. For mar.ufacturing articles, the moulding composition is hardened in closed-type press moulds at 300-500~C and under a pressure of 50-l,OOOkg/cm .

... . . .

~061039 For fibrous fillers, the starting mixture of poly-phenylenes is dissolved in chloroform, benzene, or other suitable organic solvent in amounts sufficient for forming a 20-50% solution. Powdered fillers are introduced into the polyphenylene solution while stirring, until a homogeneous mass is obtained.
A fibrous filler is impregnated with the obtained suspension. Impregnation of a fibrous filler with a solution of the polymer mixture without introducing a powdered filler is also possible.
After impregnation, the mass is vacuum or air-dried at a temperature of 70-80C for 2-3 hrs. The material obtained is processed in closed-type press moulds at temperatures ranging from 300-500C and under a pressure of 50-1,000 kg/cm .
For a better understanding of the present invention specific examples are given hereinbelow by way of illustration.
Examples 1-5 Polyphenylenes containing acetyl groups, obtained by polycyclocondensation of diacetyldiphenyloxide with acetephenone, of an approximate structural formula:

R3 ~ R3 R2 , where n = 2 - 500, Rl-- ~ O ~ ' R2 ~ ' R = - C ~

have a softening point 120-150C and number-average molecular weight, 3,700-8,000. These polymers are mixed with fillers in the following ratio tsee Table 1).

;~4 U~
~ O ~ N O

d' I ~
~` O~ ~1 d' rl~) I I I 11~ 1 1 U'l I I I I

I ~
O ~1 ') O~ 1~0 0 0 0 N ~ O O O O O

O
~~ o O IU~ O
,_1d! ~1_I N1` 1 1 1 1 1 1 N

3 _1 rl , ~
O ~~ ~ O ~ u~
~ ~ 3J 3 )ta ~~ 3 ~
o ~ O a) o tq ~ ~~ 0_1 ~ ~ ,1 ~ ~ ~ S~ ,~ S~
sU~
~ ~1) ~ O 3qO
(: O 10 ~ O ~ O rl ~1 ~
Ei ' ~4 -9_ . . .

1061~39 ~he resulting moulding composition which is a loase dark mass, is subjected to hardening in closed-type press moulds at 300-500C under a pressure of 50-1,000 kg/cm2.
The articles manufactured can be used as sliding bearings and separators for antifriction bearings; they ensure prolonged wear resistance of dry friction units operating at temperatures of 250-320C.
Examples 6-8 Polyphenylenes containing ketal groups, obtained by polycyclocondensation of ethylketals of p- or m-diacetylbenzene with acetophenone~ having an approximate structural formula:

R3 [ ~ R~ R3 R2 n , where n = 2:500 Rl- ~ ~ (Examples 6 and 7), ~

(Example 8) ; , R3= C - CH
) OCzH5 have a softening point 160-200C and number-average molecular weight 2,500-5,000~
These polymers are mixed with fillers in the following ratio (see Table 2).
The articles are manufactured from moulding composi-tions following the procedure described in Examples 1-5 and are used as linings for sliding bearings used at temperatures up to 330C.

1061~39 .
Content, wt.% E X A M P L E S
Components 1 2 3 4 5 _ _ 1. Polyphenylenes with ketal ~roups__ main fraction 8 48 72 n of main fraction 10-200 300-500 100-300 low molecular fraction 2 2 8 n of low molecular fraction 2-8 10-15 6-12 2. Molybdenum disulphide 50 30 3 3. Graphite 20

4. Tungsten disulphide 9 5

5. Tungsten diselenide - - 4

6. Talc - - 3

7. Asbestos 0,5 5

8. Copper powder - - 10

9. Nickel powder 10 - -

10. Silver powder 0,5 - _ --11, _ ,- ~
, Examples 9-13 Polyphenylenes obtained by polycondensation of di-derivatives, viz., diacetyldiphenyloxide or m-or p-diacetyl-benzene, diacetyldiphenylmethane or ketals of these compounds, and mono-derivatives, viz., acetophenone or p-ethylacetophenone, having an approximate structural formula R3 ~ ~ ~ R4 m R2 , where n = 2:500 Rl ~ ~ ~CH2~3 Examples 9, 10 Example 13 Example 12 R2 = ~~--C2H5 Examples 9-11, 13 ~o ~OC2H5 R3 and R4 = C \

are filled with fillers in the following ratio (see Table 3).
For preparing the composition, polyphenylenes are dissolved in chloroform or any other suitable organic solvent, powdered fillers (molybdenum di~ulphide, graphite boron nitride, etc.) are added, and the mixture is stirred until a homogeneous viscous mass is obtained. Carbon or graphitized fibre fabric is immersed into said mass. The impregnated fabric is dried at 70-80C for 2-3 hours. The dried impregnated mass is moulded in closed-type press moulds at a temperature range of 300-500~C
under a pressure of 50-1,000 kg~cm .

_læ
, .. .... . . .

1~61039 ~D ~
.~ , ~ 0 ,~ o ~ , o Ul In ~ ~ <~ I ~ I I I I

U~ ~o I oo o , o o o P~

~ U~
O ~1 ~7 o , o ,,, o m ~ c~
o ~ ~ o o o o _~ o~ 1 o ~ _l ~: a) ~ ~ o U ~ a,,C

a)'o o s~
~ ~ . ~ ~ ~ e ~3 ~) ~ l o o ~ Q) ~ ~::
rn~ aJ ~ e o ~ .,, ~ ~ ~ ~ ~0 3 ~o t) '4 ~ ~ ~ ~
~ ~0 ~ e c ~ o O

Co~ ~

1~)61039 The manufactured articles have hardness of 15-30 kg/mm2 and a specific impact strength from 7 to 13 kgcm/cm .
The intermediate products are used for manufacturing linings for sliding bearings, having a wear resistance.(linear wear intensity) of lxlO 8 at 320C.

~ . . ,, ~ ,

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. An antifriction polymer material which is a product derived from hardening a composition consisting of a filler in an amount of 10-95 wt.% and a binder in an amount of 5-90 wt.%, said binder comprising a mixture of polyphenylenes containing functional groups selected from ketal or acetyl groups, of the general formula:

where n= 2-500 R1=
R2=

, - , where m = 1--4;

R3 and R4 R3 and R4 being identical or different; the fraction with n= 2 amounting to 4-20% of the weight of the binder.

2. An antifriction polymer material as claimed in Claim 1, wherein said filler contains a solid lubricant selected from the group consisting of mclybdenum disulphide, graphite, boron nitride, tungsten disulphide, tungsten diselenide, and talc in amounts of 3-79% of the weight of the antifriction polymer material.

3. An antifriction polymer material as claimed in Claim 1, wherein said filler contains a fibrous material selected from the group consisting of graphitized fibre and carbon fibre in amounts of 20-90% of the weight of the antifriction polymer mate-rial.

4. An antifriction polymer material as claimed in Claim 1, wherein said filler contains metallic powders, selected from the group consisting of copper, nickel, or silver powders in amounts of 10 to 30% of the weight of the antifriction polymer material.

5. An antifriction polymer material as claimed in Claim 1, wherein said filler contains friction-regulating additives selected from the group consisting of quartz powder and asbestos in amounts of 0.5 to 5% of the weight of the friction polymer material.