JPH0224307B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a polyoxymethylene composition having extremely excellent friction and wear properties. (Prior Art) Polyoxymethylene is widely used as an engineering resin for gears, bearings, and other mechanical and electrical parts because of its excellent mechanical strength, fatigue resistance, and electrical properties. Polyoxymethylene also has excellent self-lubricating properties, and there are many applications where this property is utilized. However, it is not necessarily sufficient for applications requiring further self-lubricating properties, and it is necessary to improve the friction and wear characteristics. JP-A No. 57-5714 discloses that by adding an alkylene oxide adduct to alcohol during the polymerization of a polyoxymethylene homopolymer, the ends of polyoxymethylene were blocked with the alkylene oxide adduct to the added alcohol. The method of polymerizing the polymer and the lubricating properties of the polymer are described. (Problems to be Solved by the Invention) However, although the polyoxymethylene polymer described in JP-A-57-5714 is effective in improving lubricity to metals (S45C), it has poor lubricity to resins. Almost no effect is seen. Furthermore, there is still room for improvement regarding the lubricity to metals. (Means for Solving the Problems) The present inventors have conducted various studies to improve the lubricity of polyoxymethylene under the above-mentioned situation. The present invention was completed based on the discovery that a composition obtained by blending a polymer blocked with a substance (hereinafter referred to as a base polymer) with the same type of alcohol or an alkylene oxide adduct to an alcohol or carboxylic acid solves the above problems. That is, in the present invention, one end of a linear polymer consisting of repeating oxymethylene units has the general formula (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R2 : alkyl group, substituted alkyl group, aryl group, substituted aryl group, _R3 : hydrogen, alkyl group, substituted alkyl group,
Aryl group, substituted aryl group, m=2-6, n=
1 to 1000) with a number average molecular weight excluding terminal groups, which is capped with a compound selected from the group consisting of alkylene oxide adducts to alcohols and alkylene oxide adducts to carboxylic acids represented by
Polyacetal polymer which is 10000~500000,
general formula (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. R ₂ , R ₄ : Alkyl group, substituted alkyl group, aryl group, substituted aryl group. R ₃ : hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group, m=2~
6, n=0~2000) (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R3 : Hydrogen,
(i) Alcohol, (ii) Alkylene oxide adduct to alcohol or carboxylic acid, (iii) ) polyalkylene oxide dialkyl ether, (iv) alcohol,
A polyacetal composition containing at least one member selected from the group consisting of (v) an ester of an alkylene oxide adduct to an alcohol and a carboxylic acid, and (v) a diester of a polyalkylene oxide and a carboxylic acid. Hereinafter, the polyacetal composition of the present invention will be specifically explained. The base polymer referred to in the present invention is a linear polymer consisting of repeating oxymethylene units, and one end of the polymer is It is a polymer represented by An example of the structural formula is as follows. (l: average degree of polymerization) The polyacetal polymer represented by the above structural formula has a hydroxyl group at the end and is unstable. The hydroxyl group at the end of the polymer is unstable and is usually converted into a stable group using known methods such as esterification, etherification, and urethanization. The number average molecular weight of the portion of the base polymer consisting of repeating oxymethylene units excluding the terminal groups is the same as that of ordinary high molecular weight polyaceters, and is generally in the range of 10,000 to 500,000. The lower limit of the number average molecular weight is restricted by the physical properties of the polyacetal polymer, and the upper limit is restricted by the moldability of the polyacetal polymer. In the present invention, the alkylene oxide adduct to the alcohol or carboxylic acid forming one end of the base polymer has the general formula It is a compound having the structure represented by, and usually has the general formula R ₂ OH (R ₂ : alkyl group, substituted alkyl group,
aryl group, substituted aryl group) and

[Formula] (R ₃ : hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group) (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. m=2~6)
This is a compound to which an alkylene oxide is added. Examples of alcohol include methyl alcohol, ethyl alcohol, sec-butyl alcohol,
Hexyl alcohol, cyclohexyl alcohol, octyl alcohol, decyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, eicosanol, ceryl alcohol, myricyl alcohol, oleyl alcohol,
3-ethyl-6-undecanol, phenol,
Examples include p-butylphenol, p-octylphenol, p-nonylphenol, benzyl alcohol, and p-butylbenzyl alcohol. Among these alcohols, from the viewpoint of improving the lubricating performance of the base polymer, long-chain aliphatic alcohols having 8 or more carbon atoms and p-alkyl-substituted phenols are preferable, and from the viewpoint of easy availability, lauryl alcohol, stearyl alcohol, Particularly preferred are eicosanol, p-octylphenol and p-nonylphenol. Examples of carboxylic acids include acetic acid, propionic acid, caproic acid, 2-ethylhexanoic acid, lauric acid, valmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, ricinoleic acid, phenylacetic acid, cinnamic acid, benzoic acid, Examples include p-octylbenzoic acid and α-naphthalic acid. Among these carboxylic acids, from the viewpoint of improving the lubrication performance of the polyacetal polymer, long-chain aliphatic carboxylic acids having 8 or more carbon atoms are preferred, and from the viewpoint of easy availability, lauric acid, stearic acid, and oleic acid are preferred. and ricinoleic acid are particularly preferred. Examples of alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide,
Examples include oxetane, 3,3-bis(chloromethyl)oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, oxeban, and the like. Among these alkylene oxides, ethylene oxide and propylene oxide are particularly preferred from the viewpoint of affinity with polyacetal and ease of availability. These alkylene oxides can be used alone or in combination of two or more. Alternatively, for example, propylene oxide can be added to the alcohol first, then ethylene oxide can be added thereto, and then propylene oxide can be added thereto. The number n of moles of alkylene oxide added per mole of alcohol or carboxylic acid forming the base polymer must be in the range of 1 to 1000.
To improve the lubrication performance of the base polymer, n
It is preferable that n is large, and on the other hand, from the viewpoint of ease of production and purification, it is preferable that n is small.
Based on both of these constraints, the preferable range of n is 1 to
250, with the most preferred range being between 2 and 250. Further, the number n of moles of alkylene oxide added per mole of alcohol or carboxylic acid can be easily determined by quantifying the hydroxyl group at one end of the adduct produced. Next, the method for producing the base polymer will be described. The base polymer has the general formula (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R2 : alkyl group, substituted alkyl group, aryl group, substituted aryl group, _R3 : hydrogen, alkyl group, substituted alkyl group,
Aryl group, substituted aryl group, m=2-6, n=
In the presence of a compound selected from alcohols, carboxylic acids, or alkylene oxide adducts to alcohols and carboxylic acids represented by 0 to 1000),
Obtained by polymerizing formaldehyde.
It is desirable that alkylene oxide adducts to alcohols and carboxylic acids be purified by methods such as distillation, adsorption, and drying prior to polymerization. Further, these compounds can be used alone, or two or more kinds can be mixed and subjected to polymerization. For formaldehyde polymerization, catalysts generally known as anionic polymerization catalysts, coordination anionic polymerization catalysts, and cationic polymerization catalysts can be used. Representative groups of anionic polymerization catalysts and coordination anionic polymerization catalysts include alkali metals such as sodium and potassium, alkali metal complex compounds such as sodium-naphthalene and potassium-anthracene, alkali metal hydrides such as sodium hydride, hydrogen Alkaline earth metal hydrides such as calcium oxide, alkali metal alkoxides such as sodium methoxide and potassium t-butoxide, alkali metal carboxylates such as sodium caproate and potassium stearate, alkali carboxylates such as magnesium caproate and calcium stearate. earth metal salts, n-butylamine, diethylamine,
Amines such as trioctylamine and pyridine; quaternary ammonium salts such as ammonium stearate, tetrabutylammonium methoxide and dimethyl distearyl ammonium acetate; phosphonium salts such as tetramethylphosphonium propionate and trimethylbenzylphosphonium ethoxide; and tributyl. Examples include tetravalent organic tin compounds such as tin chloride, diethyltin dilaurate, and dibutyltin dimethoxide, and alkyl metals such as n-butyllithium and ethylmagnesium chloride. Cationic polymerization catalysts include tin tetrachloride, tin tetrabromide, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate,
So-called Friedel-Crafts type compounds such as boron trifluoride coordination compounds such as boron trifluoride acetic anhydrate and boron trifluoride triethylamine complex compounds, perchloric acid, acetyl perchlorate, hydroxyacetic acid, trichloroacetic acid, Inorganic and organic acids such as p-toluenesulfonic acid, complex salt compounds such as triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate, aryldiazinium hexafluorophosphate, aryldiazonium tetrafluoroborate, diethyl zinc , triethylaluminum, diethylaluminum chloride, and other alkyl metals. Polymerization of the base polymer is usually carried out in an organic medium. Organic media that can be used for polymerization include aliphatic hydrocarbons such as n-hexane, n-heptane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated hydrocarbons such as methylene chloride, chloroform, and trichloroethylene. Examples include aliphatic hydrocarbons and halogenated aromatic hydrocarbons such as chlorobenzene. These organic media may be used alone or in combination of two or more kinds. The formaldehyde used in the polymerization must be substantially anhydrous and must be purified using a known method such as a cold trap method or a solvent washing method. For polymerization of the base polymer, conventionally known methods such as blow polymerization and solution polymerization can be used. The molecular weight regulator is used after being uniformly dissolved or dispersed in an organic medium. The concentration of the molecular weight modifier in the organic medium can be easily determined experimentally depending on the molecular weight requirements of the desired polyacetal polymer. After the polymerized polymer is separated from the organic medium, the terminal unstable portions are blocked using, for example, acetic anhydride, a stabilizer and the like are added thereto, and the polymer is used as a base polymer. Compounds added to the base polymer include:
general formula (R ₁ : hydrogen, alkyl group, substituted alkyl group,
selected from aryl groups and substituted aryl groups, each of which may be the same or different, R ₂ , R ₄ : alkyl group, substituted alkyl group, aryl group, substituted aryl group, R ₃ : hydrogen, alkyl group , substituted alkyl group, aryl group, substituted aryl group, m=2~
6, n=0~2000) (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R3 : Hydrogen,
It is represented by an alkyl group, substituted alkyl group, aryl group, substituted aryl group, m=2-6, n=1-1000). Among Compounds A and D, the alkylene oxide adducts to alcohol and carboxylic acid may be those described in detail above. Further, as the alcohol, carboxylic acid, and alkylene oxide used in the compounds A, B, C, and D, those described in detail above can be used. Among them, lauryl alcohol, stearyl alcohol, eicosanol, p-octylphenol, and p-nonylphenol are preferable as alcohols from the viewpoint of improving lubricity and easy availability, and as carboxylic acids, lauric acid, stearic acid, oleic acid and Ricinoleic acid is preferred, and as alkylene oxides, ethylene oxide and propylene oxide are preferred. Among compounds A, B, and C, polyalkylene oxide dialkyl ether can be synthesized by dehydration condensation of the above-mentioned alkylene oxide adduct to alcohol and the above-mentioned alcohol. An ester of an oxide adduct and a carboxylic acid can be synthesized by esterifying the above alcohol or an alkylene oxide adduct to the above alcohol with the above carboxylic acid or carboxylic acid anhydride. A diester with an acid can be synthesized by esterifying the adduct of alkylene oxide to the above-mentioned carboxylic acid with the above-mentioned carboxylic acid or carboxylic acid anhydride. The number of moles of alkylene oxide added per mole of alcohol or carboxylic acid is the same as the number of moles of alkylene oxide added in the alkylene oxide adduct to alcohol or carboxylic acid used for end-blocking the base polymer due to lubricity and ease of moldability. Equal or lower is preferred. The amount of compound A, B, C or D added to the base polymer is based on 100 parts of the base polymer.
If it is less than 0.5 parts, the effect will be small, and if it exceeds 20 parts, the mechanical properties will deteriorate significantly, so it should be in the range of 0.5 to 20, but considering the optimal range of lubricity, formability, and mechanical strength. 2 to 10 parts is preferred. Stabilizer and compounds A, B, C in base polymer
Alternatively, when adding D, the base polymer and stabilizer are preferably powders, and if Compound A, B, C or D is solid, it is better to use pulverized ones as much as possible. In this way, the powdered base polymer and stabilizer and the liquid or powdered compound A, B, C or D are blended in advance using a commonly used Henschel machine, etc., and are easily molded using a commonly used extruder, injection molding machine, etc. . (Example) The present invention will be explained below with reference to Examples. Example 1 [] Production of base polymer Thoroughly dehydrated and dried paraformaldehyde was
Formaldehyde gas with a purity of 99.9% was obtained by thermal decomposition at 150°C and passing through a cooling trap several times. 110 parts per hour (The following parts indicate parts by weight.)
of formaldehyde gas, 1.0×10 ^-4 mol/tetrabutylammonium acetate, 5.0×
10 ^-3 mol/C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H (ethylene oxide adduct to stearyl alcohol, average number of moles of ethylene oxide added 70, hereinafter S-70
) was introduced into 500 parts of toluene.
At the same time as formaldehyde gas supply, 1.0×
Toluene containing 10 ^-4 mol/tetrabutylammonium acetate and 5.0×10 ^-3 mol/S-70 was continuously fed at a rate of 500 parts per hour for 3 hours. Formaldehyde gas was also continuously supplied at a rate of 110 parts per hour for 3 hours, during which time the polymerization temperature was kept at 60°C.
It was maintained at ℃. Toluene containing the polymer was continuously extracted in proportion to the amount supplied, and the polymer was separated by filtration. The polymer was thoroughly washed with acetone and then dried under vacuum at 60°C to obtain 289 parts of a white polymer. 50 parts of the polyacetal polymer thus obtained was mixed with 500 parts of acetic anhydride.
1 part, and 0.1 part of sodium acetate at 139°C for 3 hours to recover 49 parts of polymer. [] Manufacture of composition To 100 parts of the above base polymer, 0.25 part of 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol) (hereinafter abbreviated as 2246), polycaprolactam/polyhexamethylene adiva Mido/polyhexamethylene sebamide terpolymer (hereinafter referred to as
Add 0.75 parts of PA (abbreviated as PA) and 3 parts of S-70,
After mixing using a 30 mmφ extruder, the mixture was formed into a flat plate and its lubricity was measured. The results are shown in Tables 1-3. For comparison, the physical properties of a sample without S-70 were also measured (Comparative Example 1).

【table】

[Table] *2, 3 Measured under the same conditions as *2 and 3 in Table 1.

[Table] *2, 3 Measured under the same conditions as *2 and 3 in Table 1. Compatible material S45C, cart 20Kg/cm ² , linear speed 12
The friction coefficients of Example 1 and Comparative Example 1 in cm/sec are 0.25 and 0.26, respectively. Example 2 0.25 parts of 2246, 0.75 parts of PA, and 3 parts of stearyl alcohol were added to 100 parts of the base polymer obtained in Example 1 whose ends were blocked with S-70, and a 30 mmφ
After mixing using an extruder, the mixture was molded into a flat plate and its lubricity was measured. The results are shown in Tables 4-6. For comparison, the physical properties of a product without the addition of stearyl alcohol are also shown (Comparative Example 1).

【table】

[Table] Note: Measured using the same material and under the same conditions as in Table 1.

[Table] Notes: Measured under the same materials and conditions as in Table 2 Example 3 To 10 parts of the base polymer obtained in Example 1 whose ends were blocked with S-70, 0.25 parts of 2246, 0.75 parts of PA, and
C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) Add 3 parts of ₂₀ H, 30mmφ
After mixing using an extruder, the mixture was molded into a flat plate and its lubricity was measured. The results are shown in Tables 7-8. For comparison, the physical properties of a sample without the addition of the compound C ₁₈ H ₃₇ O(CH ₂ CH ₂ O) ₂₀ H are also shown (Comparative Example 1).

[Table] Note: Measured using the same material and under the same conditions as in Table 1.

[Table] Note: Measured under the same materials and conditions as in Table 4 Examples 4 to 14 2246: 0.25 part, PA: 0.75 part to 100 parts of the base polymer obtained in Example 1 whose ends were blocked with S-70. and esters of alcohols or ethylene oxide adducts to alcohols or polyethylene oxide dialkyl ethers or esters of ethylene oxide adducts to alcohols and carboxylic acids shown in Table 9, or diesters of polyethylene oxide and carboxylic acids.
After mixing using a 30 mmφ extruder, the mixture was molded into a flat plate, and the lubricity was measured. The results are shown in Table 9.

[Table] Examples 15 to 17 [] Production of base polymer Thoroughly dehydrated and dried paraformaldehyde was
Formaldehyde gas with a purity of 99.9% was obtained by thermal decomposition at 150°C and passing through a cooling trap several times. 110 parts of formaldehyde gas per hour,
1.0×10 ⁻⁴ mol/l tetrabutylammonium acetate, 5×10 ⁻³ mol/l C ₁₈ H ₃₇ O
(C ₃ H ₆ O) ₄₀ H (adduct of propylene oxide to stearyl alcohol, average number of moles of propylene oxide added is 40, hereinafter abbreviated as SP-40) was introduced into 500 parts of toluene. At the same time as formaldehyde gas was supplied, 1.0×10 ^-4 mol/l of tetrabutylammonium acetate, 5.0×10 ^-3 mol/l
Toluene containing 500 parts of SP-40 was continuously fed for 3 hours at a rate of 500 parts per hour. Formaldehyde gas was also continuously supplied at a rate of 110 parts per hour for 3 hours, during which time the polymerization temperature was maintained at 60°C. Toluene containing the polymer was continuously extracted in proportion to the amount supplied, and the polymer was separated by filtration. The polymer was thoroughly washed with acetone and then dried under vacuum at 60°C to obtain 300 parts of a white polymer. 50 parts of the polyacetal polymer thus obtained were heated at 139° C. for 3 hours with 500 parts of acetic anhydride and 0.1 part of sodium acetate, and 49 parts of the polymer were recovered. [] Manufacture of composition To 100 parts of the above base polymer, 0.25 part of 2246;
0.75 parts of PA and 3 parts of an alkylene oxide adduct to carboxylic acid shown in Table 10 were added, mixed using a 30 mmφ extruder, and then molded into a flat plate to measure lubricity. The results are shown in Table 10.

[Table] Example 18 and Comparative Example 2 [] Production of base polymer Same as Example 15 except that 1 mole adduct of propylene oxide to stearic acid or stearic acid was used instead of SP-40 in Example 15. In the same manner, the polymer of Example 18 was prepared.
50 parts and 48 parts of the polymer of Comparative Example 2 were recovered. [] Manufacture of composition 100 parts of each of the above two base polymers,
0.25 parts of 2246, 0.75 parts of PA, and 3 parts of behenyl alcohol were added, and after mixing using a 30φ extruder, the mixture was molded into a flat plate and the lubricity was measured. The results are shown in Table 11.

[Table] Example 19 and Comparative Example 3 [] Production of base polymer The base polymers of Example 18 and Comparative Example 2 were used. [] Manufacture of composition 100 parts of each of the above two base polymers,
Add 0.25 parts of 2246, 0.75 parts of PA, and 3 parts of 5 mole adduct of ethylene oxide to stearic acid, mix using a 30φ extruder, and then form into a flat plate.
Lubricity was measured. The results are shown in Table 12.

[Table] (Effects of the invention) The lubricity of the present invention is achieved by allowing the polyoxymethylene terminal-capped with an alkylene oxide adduct to alcohol or carboxylic acid to hold an alkylene oxide adduct to alcohol or carboxylic acid, or a derivative thereof. A polyoxymethylene polymer end-capped with alkylene oxide adducts to alcohols and carboxylic acids. and A polyoxymethylene composition in which an alcohol, an alkylene oxide adduct to an alcohol, a carboxylic acid, or a derivative thereof is blended with a polyoxymethylene capped with a terminal acetyl group. This is a characteristic that is not found in either. When hubs for cassette tape recorders are molded using the composition of the present invention using an injection molding machine, the number of molded hubs per unit time is almost the same as that of conventional hubs.

Claims (1)

[Scope of Claims] 1 One end of a linear polymer consisting of repeating oxymethylene units has the general formula (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R2 : alkyl group, substituted alkyl group, aryl group, substituted aryl group, _R3 : hydrogen, alkyl group, substituted alkyl group,
Aryl group, substituted aryl group, m=2-6, n=
1 to 1000) with a number average molecular weight excluding terminal groups of 10000
The general formula for polyacetal polymers is ~500,000 (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. R ₂ , R ₄ : Alkyl group, substituted alkyl group, aryl group, substituted aryl group. R ₃ : hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group, m=2~
6, n=0~2000) (R ₁ : hydrogen, alkyl group, substituted alkyl group,
They are selected from aryl groups and substituted aryl groups, and may be the same or different. _R3 : Hydrogen,
alkyl group, substituted alkyl group, aryl group, substituted aryl group, m=2-6, n=1-1000) (i) alcohol, (ii) alkylene oxide adduct to alcohol or carboxylic acid, (iii) ) polyalkylene oxide dialkyl ether, (iv) ester of alcohol or alkylene oxide adduct to alcohol and carboxylic acid, and (v) diester of polyalkylene oxide and carboxylic acid. A composition made of