RU2713446C1 - Method of obtaining antifrictional self-lubricating material for friction assemblies (versions) - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to antifriction polymer self-lubricating materials, which can be used for production of inserts and bushings of sliding bearings, separators of rolling bearings and other elements of friction units operating without lubrication and intended for use in machine building, instrument making, aircraft and shipbuilding and other fields of engineering. In the method of producing antifriction self-lubricating material in a polyolefin matrix (polyethylene, or polypropylene, or polymethylpentene, or a mixture thereof), a lubricant is introduced – ester oil with a flash point higher than 180 °C and pour point of not higher than (-50 °C) with difference of solubility parameters of lubricant and polyolefin matrix of not more than 3.5 MPa^0.5, at temperature not lower than melting points of matrix and lubricant. Polyolefin matrix is dissolved in a lubricant at the following ratio of components, wt%: ester oil – 5–50, polyolefin matrix – the rest. According to the second version, the lubricant also includes reinforcing filler at the following ratio of components, wt%: ester oil – 5–40, reinforcing filler – 5–20, polyolefin matrix – the rest. After mixing, the polymer solution is cooled, initiating its phase decomposition to form a solid polymer matrix which includes uniformly distributed lubricant microdroplets.

EFFECT: reduced viscosity and friction coefficient of antifriction self-lubricating material, capable of processing by high-efficiency methods, with simultaneous reduction of its prime cost.

2 cl, 1 dwg, 1 tbl, 11 ex

Description

The invention relates to antifriction polymer self-lubricating materials that can be used for the manufacture of bushings and bushings of bearings, cages of rolling bearings and other elements of friction units operating without lubrication and intended for use in mechanical engineering, instrument making, aircraft and shipbuilding and other technical fields.

Known anti-friction self-lubricating material (author, certificate. USSR No. 476309) based on tetrafluoroethylene with the addition of dry lubricant, polyperfluoropropylene oxide and metal powders or their alloys in the following ratio between components, wt. %: polyperfluoropropylene oxide - 2-10, dry lubricant - 0.5-20, metal powders or their alloys - 40-70, polytetrafluoroethylene - up to 100. Antifriction material wears out more slowly, it breaks in faster and has a low coefficient of friction. The disadvantage of the invention is the high cost and density of the material, as well as its non-meltability, making it impossible to process material by injection molding.

A known method of producing an antifriction self-lubricating press material (patent RU 2283326), comprising a component based on phenol-formaldehyde resin, graphite and a target additive, contains a phenoplast based on novolac phenol-formaldehyde resin, silver graphite, and, as a target additive, stearate calcium in the following ratio of components, wt. %: crushed phenoplast based on novolac phenol-formaldehyde resin - 93-94.5, silver graphite - 4-5, calcium stearate - 1.5-2.0. This composition allows you to maintain a low coefficient of friction and significantly increase the wear resistance of anti-friction self-lubricating press material due to increased strength and hardness, providing bearings and other parts of friction units made of it with a high service life, makes it possible to use the press material in aggressive environments, and also increases the quality of the parts made from it and reduces equipment maintenance costs. To obtain the material, the phenoplast powder is first loaded in half volume and mixed for the time required to warm it to 60 ° C, the second is loaded with the required amount of calcium stearate and mixed for 10-15 minutes, then the required amount of silver graphite is loaded and mixed for 10- 15 minutes, after which the remaining half of the phenolic powder is added and the mixture is thoroughly mixed for 30 minutes. The disadvantage of the invention is the use of toxic phenol-formaldehyde resin and the manufacture of products from the press material by the low-productivity method - tabletting followed by pressing in the molds.

Known antifriction self-lubricating composition (patent RU 2193577), containing copper oxide, abietic acid, liquid paraffin, graphite, copper fibers, grease and polyamide in the following ratio, wt. %: copper oxide - 7.1-10; abietic acid - 3.5-6.7; Vaseline oil - 3.5-6.7; graphite - 3.5-6.7; copper fibers - 3.5-6.7; grease - 10-10.6; polyamide - the rest. In an oven at a temperature of 60-80 ° C, the powders of nitrous oxide are dried to a moisture content of 0.25% in them, after which they prepare a sample of the components in accordance with the ratio, prepare, mix and gradually heat the mixture to a temperature of 220 ° C in a crucible until lumps, after melting, the mixture is placed in a mold heated to a temperature of 240 ° C, cooled together with the mold, removed. The composition has good anti-friction properties, wear resistance and strength. The disadvantage of the invention is the complexity and low productivity of the process of preparing the composition.

A known method of producing a self-lubricating antifriction material consisting of a polymer matrix containing a lubricant in the form of a dispersion of exfoliated graphite (patent GB2218992A). Graphite is mixed at room temperature with a mixture of concentrated sulfuric and nitric acids, kept for two hours, diluted and washed with water, dried at 80 ° C for three hours and then exfoliated in a flame at 1000 ° C. The graphite exfoliated in this way is mixed with silicone, mineral or polyalphaolefin oil and introduced into a polymer matrix selected from the group of polymers including polyphenylene sulfide and other polyarylene sulfides; polyether ether ketone; polyether ketone; polyphenylene ethers and other polyaryl ethers; polyarylketones, polysulfones; polyoxybenzoyl polyesters; perfluoroalkoxy polymers; polymers of fluoroethylene propylene ether; fluorine-containing ethylene-propylene polymer; polyvinylidene difluoride; polytetrafluoroethylene; aromatic polyesters (polyarylates); aromatic polyamides; polyetherimide; polyamidimide; polyimidesulfone; polyimides; self-reinforcing (liquid crystal) polymers; conductive polymers such as polypyrroles and polyacetylenes; silicone resins; thermosetting resins (such as phenolic; phenol-toluene-formaldehyde; cresyl; furan; epoxy); copolymers of ethylene and tetrafluoroethylene; polychlorotetrafluoroethylene; polyesters (such as polyethylenetetrafthalate and polybutylene phthalate); polyamides (such as nylon 6 and nylon 66); acetal homopolymer and acetal copolymer; high molecular weight polyethylene, to a graphite content of from 3 to 60 wt. % Compositions can be processed into finished products by methods such as injection molding, extrusion, pressing, casting, etc., and are characterized by high wear resistance, low friction coefficients and good mechanical strength.

The disadvantage of the invention is the complexity and high cost of the procedure for obtaining self-lubricating material, as well as an insufficient decrease in the coefficient of friction due to the coarse-grained structure of the lubricant and the uneven distribution in the volume of antifriction material.

The known method for the combination of essential features and the technical result is adopted as the closest analogue of the invention (prototype).

The objective of the invention is to obtain anti-friction self-lubricating material, characterized by a low coefficient of friction and capable of processing high-performance methods due to low viscosity, according to a simplified procedure and using less material resources to reduce its cost.

The problem is solved in that in the method for producing anti-friction self-lubricating material by introducing a lubricant including oil into the polyolefin matrix at a temperature not lower than their melting points and mixing the components, ester oil with a flash point above 180 ° C and pour point is used as a lubricant not higher than -50 ° C, polyethylene, or polypropylene, or polymethylpentene, or a mixture thereof, when the solubility parameters of the lubricant and polyolefin matrix are used, are used as the polyolefin matrix Ritsa not more than 3.5 MPa, ^0.5, and polyolefin matrix is dissolved in the lubricant in the following ratio, wt. %:

ester oil 5-50 polyolefin matrix rest;

then the resulting polymer solution is cooled, initiating its phase decomposition with the formation of a solid matrix, including uniformly distributed microdroplets of lubricant.

According to another embodiment of the invention, the problem is solved in that in the method for producing anti-friction self-lubricating material by introducing a lubricant comprising oil into the polyolefin matrix at a temperature not lower than their melting points and mixing the components, ester oil with a flash point above 180 is used as a lubricant ° C and pour point not higher than -50 ° C, polyethylene, or polypropylene, or polymethylpentene, or a mixture of them with a difference in pairs, is used as a polyolefin matrix ters solubility lubricant and a polyolefin matrix is not more than 3.5 MPa, ^0.5, and polyolefin matrix is dissolved in the lubricant and filler used as reinforcing filler in the following ratio, wt. %:

ester oil 5-40 reinforcing filler 5-20 polyolefin matrix rest;

then the resulting polymer solution is cooled, initiating its phase decomposition with the formation of a solid matrix, including uniformly distributed microdroplets of lubricant.

In FIG. 1 shows an SEM image of an antifriction self-lubricating material based on polymethylpentene containing 45% lubricant.

The polyolefin matrix (polyethylene, or polypropylene, or polymethylpentene, or a mixture thereof) is dissolved in ester oil at an elevated temperature, the article is formed from a polymer solution and cooled. During cooling, as a result of the phase decomposition of the polymer solution, a solid polymer matrix is formed, which includes uniformly distributed microdroplets of the lubricant, the presence of which in a finely dispersed state causes a low coefficient of friction of the material.

According to the invention, any polyolefin can be used as a polyolefin matrix — polyethylene, polypropylene, polymethylpentene, a mixture thereof. As ester oil, di- and triesters with a flash point of at least 180 ° C and a pour point of no higher than -50 ° C can be used; the use of 2-ethylhexanol, isodecanol, isonanol, octanol, isoheptanol, butanol, glycerol, pentaerythritol esters is more preferable. and etriol. As the reinforcing filler, any filler with anisometric particles can be used; the use of glass and carbon fibers is more preferable.

The technical result that can be obtained from the use of the invention is to reduce the viscosity and coefficient of friction of a self-lubricating antifriction material that can be processed by high-performance methods, while reducing cost due to a decrease in the complexity and material consumption of the production process.

The following examples illustrate the proposed technical solution. The viscosity of the materials is measured at a mixing temperature on a DHR-2 rotational rheometer (TA Instruments) using a cone-plane working unit at a shear rate of 100 s ^-1 . The friction coefficient is measured on the same device at 25 ° C under the conditions of friction of a steel disk on the surface of the material with a force of 10 N and an angular velocity of 10 rad / s.

Anti-friction self-lubricating material can be obtained using different concentrations of lubricant in the polymer matrix: with increasing lubricant content, the friction coefficient and melt viscosity decrease (Examples 1-5). Moreover, even with a high content of lubricant, it has submicron sizes (0.2-0.8 μm) and is evenly distributed in the bulk of the material (Fig. 1). As the ester oil, both diesters and triesters can be used, which provides the resulting material with a comparable level of properties (Examples 5-7). As the polyolefin matrix can be different polyolefins processed at different temperatures (Examples 5, 8, 9), as well as mixtures thereof (Example 10); this allows you to choose the material with the required rigidity and processing temperature as the polyolefin matrix. Also, a reinforcing filler can be added to the composition of the self-lubricating material, which allows to further reduce the friction coefficient, but increases the melt viscosity (Example 11).

Example 1

To obtain anti-friction self-lubricating material, 15 g of 2-ethylhexanol ester and sebacic acid (diisooctylsebacinate, solubility parameter 17.5 MPa ^0.5 , flash point 210 ° C, pour point -60 ° C) are mixed with 85 g polymethylpentene (solubility parameter 15.1 MPa ^0.5 ) at 240 ° C for 15 min, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 2

Anti-friction self-lubricating material is obtained analogously to the method described in example 1, but using 40 g of diisooctylsebacinate and 60 g of polymethylpentene. Material characteristics are given in the table.

Example 3

Anti-friction self-lubricating material is obtained similarly to the method described in example 1, but using 45 g of diisooctylsebacinate and 55 g of polymethylpentene. Material characteristics are given in the table. A micrograph of the material obtained with a Hitachi TM3030Plus electron scanning microscope is shown in FIG. 1.

Example 4

Antifriction self-lubricating material is obtained analogously to the method described in example 1, but using 50 g of diisooctylsebacinate and 50 g of polymethylpentene. Material characteristics are given in the table.

Example 5

To obtain anti-friction self-lubricating material, 50 g of ethriol ester and heptanoic acid (triheptanoylethriol, solubility parameter 18.1 MPa ^0.5 , flash point 235 ° C, pour point -66 ° C) are mixed with 50 g polymethylpentene at 240 ° C for 15 minutes, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 6

Self-lubricating antifriction material is obtained similarly to the method described in example 5, but isonanol and phthalic acid ester (diisononyl phthalate, solubility parameter 18.1 MPa ^0.5 , flash point 221 ° C, pour point -50 ° C) are used instead of triheptanoylethriol. Material characteristics are given in the table.

Example 7

To obtain anti-friction self-lubricating material, 50 g of diisooctyl sebacinate are mixed with 50 g of polyethylene (solubility parameter 17.1 MPa ^0.5 ) at 180 ° C for 15 minutes, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 8

To obtain anti-friction self-lubricating material, 50 g of octanol ester and adipic acid (diisooctyl adipate, solubility parameter 17.6 MPa ^0.5 ) are mixed with 50 g of polypropylene (solubility parameter 18.8 MPa ^0.5 , flash point 196 ° C, pour point -70 ° C) at 180 ° C for 15 minutes, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 9

To obtain an anti-friction self-lubricating material, 40 g of diisooctyl sebacinate, 30 g of polyethylene and 30 g of polypropylene are mixed at 180 ° C for 15 minutes, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 10

To obtain anti-friction self-lubricating material, 45 g of diisooctylsebacinate, 45 g of polymethylpentene and 10 g of fiberglass are mixed at 240 ° C for 15 min, then the homogenized polymer solution is given the desired shape and cooled. Material characteristics are given in the table.

Example 11

Anti-friction self-lubricating material is obtained similarly to the method described in example 10, but carbon fiber is used instead of fiberglass. Material characteristics are given in the table.

In all cases, anti-friction self-lubricating materials are characterized by a significantly lower viscosity compared to the viscosity of the used polyolefin matrix (the viscosity of polymethylpentene is 2430 Pa⋅s, polyethylene 2010 Pa⋅s, polypropylene 933 Pa⋅s), which makes it easy to form products from them , as well as a significantly lower coefficient of friction (the coefficient of friction of polymethylpentene is 2.12, polyethylene - 2.03, polypropylene - 0.9).

Claims (6)

1. A method of producing an anti-friction self-lubricating material by introducing a lubricant including oil into the polyolefin matrix at a temperature not lower than their melting points and mixing the components, characterized in that ester oil with a flash point above 180 ° C and a pour point of not above -50 ° C, polyethylene or polypropylene or polymethylpentene is used as the polyolefin matrix, or a mixture thereof, with a difference in the solubility parameters of the lubricant and the polyolefin matrix, not more than 3.5 ^0.5 MPa, and a polyolefin matrix is dissolved in the lubricant in the following ratio, wt.%: ester oil 5-50 polyolefin matrix rest, then the obtained polymer solution is cooled and its phase decomposition is initiated with the formation of a solid matrix, including uniformly distributed microdroplets of the lubricant. 2. A method of producing an antifriction self-lubricating material by introducing a lubricant including oil into the polyolefin matrix at a temperature not lower than their melting points and mixing the components, characterized in that ester oil with a flash point above 180 ° C and a pour point of not above -50 ° C, polyethylene or polypropylene or polymethylpentene is used as the polyolefin matrix, or a mixture thereof with a difference in the solubility parameters of the lubricant and the polyolefin matrix of not more than 3.5 MPa ^0.5 , and the polyolefin matrix is dissolved in the lubricant and a reinforcing filler is used as a filler in the following ratio of components, wt. %: ester oil  5-40 reinforcing filler  5-20 polyolefin matrix  rest, then the obtained polymer solution is cooled and its phase decomposition is initiated with the formation of a solid matrix, including uniformly distributed microdroplets of the lubricant.

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