JPH01307514A - Porous sheet for sliding and adhesive sheet for sliding - Google Patents

Abstract

PURPOSE:To improve heat resistance and resistance to wear by dispersedly containing a specified amount of polyimide powder in a polytetrafluoroethylene resin, and specifying porosity of the resine. CONSTITUTION:Polyimide powder is dispersedly contained in a polytetra- fluoroethylene resin at the amount of 1 to 50wt. percent, and porosity of the resine is determined to be 5 to 55 percent. The polyimide powder acts as a filler material in PTFE, and is typically obtained by converting polyamide acid obtained by the reaction of aromatic tetracarboxylic acid dianhydride on aromatic diamine into imide. When the new material is used as a sheet, damage to mating materials is reduced, and heat resistance and resistance to wear are also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sliding porous sheet and a sliding adhesive sheet using a polytetrafluoroethylene base polymer.

<Prior Art> Conventionally, sliding members made of polytetrafluoroethylene (hereinafter referred to as PTFE) have been known. PTFE has excellent low-friction properties, so it can be suitably used as a sliding member that does not require a lubricant.

However, since PTFE has extremely poor abrasion resistance and compression creep resistance compared to other resins, sliding members using PTFE are usually filled with fibrous materials such as glass fibers and carbon fibers. compensates for the shortcomings of

When sliding members filled with these fibrous materials are used on soft metals such as aluminum, brass, and copper as mating materials, the metal is damaged due to contact between the fibrous materials and the metal, and as a result, the damaged metal is used as a sliding member. The degree of wear increases as parts are scraped off. In addition, when the degree of wear increases, heat is generated during sliding, sometimes exceeding the softening point of PTFE, which may cause creep deformation or seizure to the mating material. This phenomenon is particularly noticeable in dry sliding friction sliding under high loads and high speeds.

In recent years, solid inorganic fillers such as graphite, molybdenum disulfide, carbon fiber, and copper powder, polyether sulfone, Heat-resistant organic resin powders such as oxybenzoyl polyester, polyamideimide, and polyetherketone are used.

However, inorganic fillers significantly damage the mating material and wear out more than organic fillers, and although the above organic fillers usually exhibit good wear resistance, they have poor heat resistance. Seizing and abnormal wear occur during sliding, which is a problem in applications that require heat resistance.

On the other hand, when an adhesive layer is provided on a sheet made of PTFE to make a sliding adhesive sheet, the surface of the PTFE sheet is extremely inert, so sufficient adhesion strength is ensured at the interface between the sheet and the adhesive layer. This may result in anchor failure during sliding.

In order to improve these difficulties, for example, the surface of the PTFE sheet may be etched with a sodium-ammonia complex salt or a sodium-naphthalene complex compound, or filler powder such as PTFE powder and metal oxide powder may be added to the surface of the sheet. A method has been proposed in which a mixture layer is formed by coating and heating a dispersion containing . However, in the former case, there are problems in the coloring of the sheet and in the durability of the etching effect, and in the latter case, the surface of the filler powder is likely to be coated with PTFE, and it may not be possible to improve the anchoring force by adding the filler.

<Problem to be solved by the invention> The present invention has been made in view of the above circumstances.
Provided is a sliding sheet that causes less damage to mating materials when used as a sliding sheet, has excellent heat resistance and abrasion resistance, and has excellent anchoring properties even when an adhesive layer is provided on its surface. The purpose is to

<Means for Solving the Problems> As a result of intensive studies to achieve the above object, the present inventors have found that a sheet made of PTFE containing a specific amount of polyimide powder is porous to have a specific porosity. The present inventors have discovered that an excellent sliding sheet that solves the above-mentioned problems can be obtained by making the above-mentioned problems a reality, and have completed the present invention.

That is, in the present invention, in polytetrafluoroethylene resin,
A porous sheet for sliding, characterized by containing 1 to 50% by weight of polyimide powder dispersed therein and having a porosity of 5 to 50%, and a porous sheet for sliding, comprising an adhesive layer provided on one side of the sheet. This invention relates to adhesive sheets.

The polyimide powder used in the present invention acts as a filler in PTFE, and is typically obtained by imidizing polyamic acid obtained by reacting aromatic tetracarboxylic dianhydride with aromatic diamine. That's what you get. Examples of such aromatic tetracarboxylic dianhydrides include romellitic acid, 3.3', 4.4'-
Biphenyltetracarboxylic acid, 2.3.3', 4'-
Biphenyltetracarboxylic acid, 1.2.4.5-naphthalenetetracarboxylic acid, 1゜2.5.6-naphthalenetetracarboxylic acid, 2.3.6.7-naphthalenetetracarboxylic acid, 3.3', 4 .4'-benzophenonetetracarboxylic acid, 2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane, 4゜4''-bis(
Examples include dianhydrides of tetracarboxylic acids such as 2,3-dicarboxyphenoxy)diphenyl ether, oxides thereof, lower alkyl esters, polyhydric alcohol esters, etc. These may be used alone or in combination of two or more. You can. In the present invention, the aromatic tetracarboxylic dianhydride may be partially converted into an arbitrary amount of aliphatic tetracarboxylic dianhydride such as 1,2,3,4-butanetetracarboxylic dianhydride. You can also use it by replacing it.

Further, examples of the aromatic diamine to be reacted with the aromatic tetracarboxylic dianhydride include 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-
Diaminodiphenyl ether, 313'-dimethoxy-
Diphenyl ether type diamines such as 4,4゛-diaminodiphenyl ether, 3゜3''-diaminodiphenyl ether, 3,4゛-diaminodiphenyl ether or diphenylthioether type diamines such as their thioethers, 4,4'-diaminobenzophenone, 3,
3"-dimethyl-4,4"-diaminobenzophenone,
3.3'-Diaminobenzophenone and other benzophenone diamines, 3,3''-diaminodiphenylmethane,
Diphenylmethane diamines such as 4.4'-diaminodiphenylmethane, 3.3"-dimethyl-4,4"-diaminodiphenylmethane, 2.2'-bis(4-aminophenyl)propane, 2.2'-bis(3 -aminophenyl)propane and other bisphenylpropane diamines, 4,4'-diaminodiphenyl sulfoxide, 3,3
Diphenylsulfoxide diamines such as '-diaminodiphenylsulfoxide, diphenylsulfone diamines such as 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone, benzidine, 3.
Biphenyl diamines such as 3"-dimethylbenzidine, 3,3'-dimethoxybenzidine, 3.3"-diaminobiphenyl, 2,6. -diaminopyridine, 2,5.
-diaminopyridine, 3,4. -Pyridine diamines such as diaminopyridine, o-, to- or p-diaminobenzene, 3,5-diaminobenzoic acid, 4.4''-di(doaminophenoxy)diphenylsulfone, 4.4'
-di(p-aminophenoxy)diphenylsulfone, 4
゜4゛-di(doaminophenoxy)diphenyl ether, 4.4''-di(p-aminophenoxy)diphenyl ether, 4.4゛-di(doaminophenoxy)diphenylpropane, 4.4゛-di(p-ru) Aminophenoxydiphenylpropane, 4,4'-di(Ill-aminophenylsulfonyl) diphenyl ether, 4,4'-di(
p-aminophenylsulfonyl) diphenyl ether,
4.4'-di(m-aminophenylthioether) diphenyl sulfide, 4,4'-di(p-aminophenylthioether) diphenyl sulfide, 4.4'-di(
Doaminophenoxy)diphenylketone, 4.4゛-di(p-aminophenoxy)diphenylketone, 4.4°
-di(m-aminophenoxy)diphenylmethane, 4,
4'-di(p-aminophenoxy)diphenylmethane,
2,5-diaminotoluene, 2,4-diaminoxylene, diaminodurene, 1,5-diaminonaphthalene, 2
, 6-diaminonaphthalene and the like. These diamines may be used alone or in combination of two or more. Further, the aromatic diamine may be partially substituted with an aliphatic diamine.

Examples of the organic polar solvent used as a reaction solvent for the aromatic tetracarboxylic dianhydride and aromatic diamine include N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, hexamethylenephosphorotriamide, and pyridine. and phenols such as cresol, phenol, and xylenol.

In addition, along with the above solvents, hexane, benzene, toluene,
Organic solvents such as xylene and alcohols may be used in combination.

The polyimide powder used as a filler in the present invention can be obtained, for example, by the following method.

Aromatic tetracarboxylic dianhydride is added little by little into a solution of aromatic diamine and an organic polar solvent (diamine concentration 1 to 30 mol%, preferably 5 to 10 mol%) to gradually advance the reaction, Synthesizing polyamic acid Next, the temperature is raised to a temperature of 140 to 250 °C for a relatively short period of time, for example, at a heating rate of about 10 °C/min while stirring, and condensed water accompanying imide conversion is removed from the reaction system. While doing so, an imidization reaction is gradually carried out to precipitate polyimide particles to form a slurry-like polyimide solution. The resulting slurry solution is cooled, filtered, washed, and dried to obtain a polyimide powder having the powder characteristics of the present invention.

The logarithmic viscosity of the polyamic acid obtained before imidization in the above reaction is 0.1 to 1.2 (30°C, 0.5g/100
m1 in dimethylacetamide (hereinafter referred to as DMAC)
, preferably from 0.3 to . By adjusting the logarithmic viscosity to a range of 0.8, the logarithmic viscosity can be adjusted to 0.1 to 0.5 (30°C, 0.5
A polyimide of low molecular weight is obtained. Also, for the same reason, the solution viscosity was measured by a rotational viscometer (B type) from 1 to 50 boids (polymer concentration 7.
(5% by weight, 30°C), preferably in the range of 5 to 20 voids.

In order to adjust the viscosity of the above-mentioned solution, especially the logarithmic viscosity, it is possible to hydrolyze the polyamic acid by adding a solvent such as water or methanol to the polyamic acid solution, or to add a solvent such as water or methanol to the polyamic acid solution.
A method such as heating at a temperature of 00-"C or lower can be used, but in order to uniform the particle size and grain size of the desired polyimide powder with good reproducibility, the amount of monomer blended must be strictly controlled during the reaction. is preferred.

In addition, in order to make the heat distribution of the reaction system uniform and smoothly perform the imidization reaction to obtain the polyimide powder of the present invention, the stirring speed during the reaction was set at 50 to 400 rpm.
Preferably the range is 100 to 300 rpm, and the monomer concentration during the reaction is 5 to 50% by weight, preferably 10 to 30% by weight.
The range is by weight%.

In addition, in the present invention, in order to accelerate the imidization reaction, shorten the reaction time, and efficiently obtain polyimide particles, pyridine, 2-chloropyridine, 24.6-collidine, 2
．． 6-dichloropyridine, α, β, γ-picoline, 4-
Phenylpropylpyridine, 2-propylpyridine, 2
．． and lysines such as 4-lutidine, 2.5-lutidine, 2.6-lutidine, and 3.4-lutidine; aliphatic compounds such as triethylamine, trimethylamine, N,N-dimethyldodecylamine, triethylenediamine, and tri-n-butylamine; Tertiary amines, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole,
1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole,
imidazoles without active hydrogen such as N, N-
Aromatic tertiary amines such as dimethyl-p-)luidine, N,N-dimethylbenzylamine, tertiary amines such as 1,8-diazabicyclo(5,4,O)undecene-7 and its acid complexes. The tertiary amine can be added in an amount of 0.5 to 1.5 mol % to each amide group of the polyamic acid. Furthermore, during the reaction, 0.2 to 3
Since the molecular weight can be controlled by adding within the range of 0 mol %, polyimide powder having desirable properties can be obtained.

The polyimide powder obtained as described above usually has a spherical shape and has an average particle size of 3 to 15 μm, preferably 5 to 1 μm.
0 μm, particle size distribution of 0.1 to 50 μm, preferably 1 to 50 μm
It is preferable to adjust the thickness to a range of 30 μm. If the average particle size is outside the above range, it will be difficult to disperse uniformly when blended with PTFE as a filler, and the powder will tend to aggregate, making it difficult to obtain sufficient mechanical strength and elongation when used as a sliding sheet. In addition, if the particle size distribution is less than 0.1 μm, the bulk density will be small, and when blending polyimide powder, it may not be possible to achieve sufficient uniform dispersion. Contained in the form of aggregates, the strength and elongation of the sheet decrease and the amount of wear increases.On the other hand, 50
If it exceeds μm, the average particle size of the polyimide powder is large and it tends to form aggregates with many voids, which prevents uniform dispersion and results in a sheet containing aggregates, and the specific gravity becomes low.As a result, strength and elongation decrease, resulting in a loss of wear. shows a tendency to increase.

Furthermore, from the viewpoint of heat resistance against heat generation during sliding, it is preferable that the polyimide powder has a heat distortion temperature of 350°C or higher, and structurally, it is preferable to use aliphatic tetracarboxylic dianhydride or aliphatic diamine. Fully aromatic polyimide is preferable.

PTFE filled with the polyimide powder in the present invention
has a repeating unit represented by (CFz -CFz)- as its main structure, and is generally Polyflon M-12, M-
31 (manufactured by Daikin Industries), Teflon T-7-J, T-
Commercially available products such as 820-J (manufactured by Mitsui Fluorochemical Co., Ltd.) are preferably used.

Furthermore, in the present invention, the PTFE is mixed with polyimide powder to form a sheet, so it is preferable to use it in powder form, and from the viewpoint of uniform dispersibility, a powder that can pass through a 10-mesh sieve is preferable.

In order to improve the mechanical properties and abrasion resistance of the porous sheet for sliding of the present invention, the polyimide powder is dry-mixed or wet-mixed with PTFE in an amount of 1 to 50% by weight, preferably 10 to 30% by weight. Mix and disperse uniformly.

If the content of polyimide powder is less than 1% by weight, the resulting sliding sheet will not have sufficient abrasion resistance, and furthermore, when an adhesive layer is provided on the surface of the sheet, it is not possible to expect much improvement in anchoring force. On the other hand, when the content exceeds 50% by weight, the properties of polyimide become dominant in the sliding properties of the sheet.
Not only is it difficult to form a sheet, but it also becomes difficult to obtain sufficient sliding properties of PTFH.

In order to obtain the sliding porous sheet of the present invention, a known method can be adopted. For example, PTFE powder and polyimide powder are mixed in an arbitrary amount, compression molded and preformed into a shape such as a round bar, A method for producing a porous sliding sheet by firing and cutting this is included. In addition, in the present invention, as long as it does not affect wear resistance or damage to the mating material,
If necessary, fillers such as graphite, molybdenum disulfide, carbon fiber, and polyamide fiber may be used in combination.

The sliding porous sheet obtained by the present invention has a porosity of 5 to
50%, preferably 10-30%, and porosity is 5%
If it is less than 50%, it may not be possible to obtain sufficient anchoring force when an adhesive layer is provided, and if it exceeds 50%, it may be difficult to obtain a sheet with uniform porosity, and the mechanical strength of the sheet itself may be impaired. This may cause the sheet to be damaged during sliding.

The sliding porous sheet obtained as described above can be made into an adhesive sheet by providing an adhesive layer on one side thereof. There are no particular restrictions on the type of adhesive, but in consideration of heat generation during sliding, it is preferable to use a thermosetting adhesive. For example, a known thermosetting adhesive such as epoxy resin or phenolic resin may be used. 5-100μ
It is preferable to provide the film with a thickness of approximately 100 m. In addition, clay, talc,
It is also possible to add fillers such as calcium carbonate, silica, barium carbonate, etc., or to embed a laminating base film or sheet such as paper, cloth, glass paper, glass fiber, etc. into the adhesive layer for reinforcement. . Furthermore, additives such as a heat stabilizer, an anti-aging agent, and a curing accelerator can be added as necessary.

The sliding porous sheet of the present invention obtained in this manner has excellent abrasion resistance and heat resistance, hardly damages the mating material during sliding, and exhibits an excellent sliding effect when scratched. Also,
Adhesive sheets with an adhesive layer formed on one side have excellent anchoring properties,
The anchor will not be damaged during sliding use. Therefore, the sliding porous sheet of the present invention has heat resistance, chemical resistance, and abrasion resistance for heat-sensitive sliding members used in copying machines, facsimile machines, printers, etc., piston rings and bearings used in compressors, etc. Can be used for sliding parts as required.

<Effects of the Invention> As described above, the porous sheet for sliding of the present invention is made into a porous sheet using polyimide powder as a filler for PTFE resin, and has a porosity within a specific range, so it is suitable for sliding use. In this case, a part of the sliding member is transferred to the mating material such as a soft metal at the initial stage of sliding to form a protective film, and exhibits excellent sliding properties without using a lubricant. Moreover, compared to conventional sliding members, it does not damage the mating material, has appropriate hardness, and has significantly improved wear resistance. Furthermore, it has excellent heat resistance, especially when used as an adhesive sheet with a thermosetting adhesive layer on one side, since polyimide powder is used as a filler and the porosity is within a specific range. It has extremely good anchoring properties and heat resistance,
The anchor will not break due to heat generated during sliding use.

<Examples> Examples of the present invention will be shown below and explained in more detail.

Example 1 PTFE (Polyflon M-12. Manufactured by Daikin Industries)
was crushed in a mixer, passed through a 10-mesh sieve, and Lomelift acid dianhydride and 4,4°-
Average particle size obtained from diaminodiphenyl ether: 10
μm, particle size distribution 3-20 μm 1 Logarithmic viscosity 0.3 (30℃
, 0.5 g/100ml? 20% by weight of polyimide powder (in sulfuric acid) was blended as a filler.

Mixing is done with a Henschel mixer, 100-100
After preforming at a pressure of 0 kg/cJ, it was fired at a temperature of 370°C, and then cut into a sheet.

The porosity of this sheet is 15% and the thickness is 500μm
Met.

Next, a thermosetting adhesive consisting of 100 parts by weight of bisphenol-type epoxy resin, 300 parts by weight of carboxy-modified acrylonitrile-butadiene rubber, and 400 parts by weight of methyl ethyl ketone was applied to one side of the obtained porous sheet using an applicator, and dried. An adhesive layer having a thickness of 10 μm was formed to obtain an adhesive sheet.

Example 2 A sliding porous sheet (porosity: 30%, thickness: 500 μm) of the present invention was produced in the same manner as in Example 1, except that the polyimide powder used in Example 1 was contained in an amount of 40% by weight.

The thermosetting adhesive layer used in Example 1 was formed on this sheet in the same manner as in Example 1 to prepare an adhesive sheet.

Example 3 A sliding material of the present invention was produced in the same manner as in Example 1, except that 20% by weight of polyimide powder consisting of 3.3'4.4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine was contained. Porous sheet (porosity 15%, thickness 5
00 μm) was created.

The thermosetting adhesive layer used in Example 1 was formed on this sheet in the same manner as in Example 1 to prepare an adhesive sheet.

Comparative Example 1 A sliding porous sheet (porosity 15%) was prepared in the same manner as in Example 1 except that polyimide powder as a filler was not blended.
, 500 μm thick) was prepared, and a thermosetting adhesive layer was formed.

Comparative Example 2 A sliding porous sheet (
A porosity of 5% and a thickness of 500 μm) was prepared, and a thermosetting adhesive layer was formed.

The anchoring force and abrasion resistance of the sliding porous sheets (adhesive sheets) obtained in each of the above Examples and Comparative Examples were measured according to the following methods, and the results are shown in Table 1.

In addition, the measurement used a sample obtained by pressing a sample on iron (S-45G) at a temperature of 170° C. and a condition of 50 kg/cffl for 1.5 hours.

The anchoring force was measured using an Autograph AGB model (manufactured by Shimadzu Corporation).

In addition, wear resistance was measured by rotating and sliding an aluminum sleeve-like ring (outer diameter 25.6 vm, inner diameter 2011 mm, height 10 n).

(Hereafter, margin) Table 1 *) Sliding test conditions:

Claims (2)

[Claims] (1) A porous sheet for sliding, comprising 1 to 50% by weight of polyimide powder dispersed in a polytetrafluoroethylene resin and having a porosity of 5 to 50%. (2) A sliding adhesive sheet comprising the porous sliding sheet according to claim (1) with an adhesive layer provided on one side thereof.