JPH03292314A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To obtain a polyacetal resin composition excellent in slidability such as friction and abrasion properties by mixing a specified polyacetal block polymer with a specified graft copolymer and a specified oxyalkylene adduct in a specified ratio. CONSTITUTION:The title composition is obtained by mixing 100 pts.wt. polyacetal block polymer which is derived by blocking one end of a linear polymer comprising repeating oxymethylene units with an alcohol/alkylene oxide adduct of formula I [wherein R1 and R1' are each H, (substituted) alkyl or (substituted) aryl; R2 is (substituted) alkyl or (substituted) aryl; m is 2-6; and n is 1-1000] with 0.5-25 pts.wt. graft copolymer derived by chemically combining an olefin copolymer comprising an alpha-olefin and an alpha,beta-unsaturated acid glycidyl ester with a (co)polymer consisting of repeating units of formula II (wherein R3 is H or lower alkyl; and X is a group of formula III or IV or the like), and 20 pts.wt. or below oxyalkylene adduct of formula V [wherein R4 and R5 are each H or (substituted) alkyl; R6 is a (substituted) hydrocarbon group or aliphatic or aromatic acyl; m' is 2-6; and n' is 0 or 1-2000].

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyacetal resin composition that has excellent sliding properties such as friction and abrasion properties.

More specifically, the present invention relates to a polyacetal resin composition that can be used for parts that particularly require self-lubricating properties, such as automobile parts, electrical and electronic parts, and mechanical parts, and which can provide molded products with extremely excellent friction and wear properties. .

[Prior Art] Conventionally, polyacetal has been widely used in, for example, automobile parts, electrical parts, gears, bearings, and other mechanical parts because of its excellent mechanical properties, electrical properties, creep properties, and friction and wear resistance properties. It is used. Polyacetal also has excellent self-lubricating properties, and is used in a variety of applications that take advantage of this property. However, this is not necessarily sufficient for applications requiring self-lubricating properties, and there is a strong desire for improved friction and wear properties.

As a conventional technique for improving the lubricating properties of polyacetal, Japanese Patent Application Laid-open No. 57-5714 discloses combining polyacetal with an ester lubricant and low density polyethylene. However, the polyacetal resin composition prepared by this method does not have satisfactory lubricity toward metals or resins, and in particular, the lubricity toward resins is hardly improved. Also, Japanese Patent Application Publication No. 1982
JP-187551 discloses that a lubricant and a crystal nucleating agent having oxyalkylene units are blended into a polyacetal block polymer having an alkylene oxide adduct introduced at one end to improve sliding properties.

However, although the lubricity for both metals and resins has been improved, the coefficient of friction and amount of wear are still large when used in i-tight parts, and it is not satisfactory for use without grease. do not have.

[Problems to be Solved by the Invention] Under these circumstances, the object of the present invention is to provide a greaseless, extremely excellent friction and wear property that can be suitably used in various parts that require self-lubricating properties. An object of the present invention is to provide a highly lubricating polyacetal resin composition that can give molded products with high lubricity.

[Means and effects for solving the problem, that is, the present invention provides that (1) one end of a linear polymer consisting of repeating oxymethylene units has the general formula H> (R+, R'1: hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group, and adjacent R
1. Adjacent R'1 and R, , R' are the same or different. R2: alkyl group, substituted alkyl group, aryl group, substituted aryl group, m==2-6, n=1-1,000
) Polyacetal block polymer 10 capped with alkylene oxide adduct to alcohol represented by
(2) an olefin-based copolymer (a) consisting of an α-olefin and a glycidyl ester of an α,β-unsaturated acid;
Graft copolymer in which one or more species of polymer or copolymer (b) composed of repeating units represented by the following formula (IIb) are chemically bonded in a branched or crosslinked structure: 0.5 to 25 parts by weight, X (However, R3 is hydrogen or a lower alkyl group, X is -COO
CIIs, -f;00zlls, -CO
OC4tie.

-COO(:1hCIl (C2115) C mountain, =c
(3)-Formula (II+) R4 loni5 (R4 and R5 in the formula each have a hydrogen atom or a substituent, or adjacent R4, adjacent R6 and R4,n are the same or different.R6 is a hydrocarbon group or an aliphatic or aromatic acyl group with or without a substituent, m ' is an integer of 2 to 6, and n' is an integer of 0 or 1 to 2000). The present invention provides an excellent polyacetal resin composition.

(1) Component polyacetal block polymer is a linear polyacetal polymer consisting of repeating oxymethylene units (-ocH2-), in which one end has the general formula (R,, R',: hydrogen, alkyl group, substituted alkyl basis,
Adjacent R1 selected from aryl groups and substituted aryl groups
, adjacent n'1 and R, , R' are the same or different. R2: alkyl group, substituted alkyl group, aryl group,
It is a polymer capped with an alkylene oxide adduct to an alcohol represented by a substituted aryl group, m=2 to 6, n=1 to 1,000).

Specifically, it is a linear polymer consisting of repeating oxymethylene units, and one end of the polymer is blocked with a structural formula as shown below.

( ): average degree of polymerization, Ro = hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group) The alkylene oxide adduct to alcohol that blocks one end of the polyacetal polymer is a - formula compound and is usually - Alcohol represented by the formula R20H (R2: alkyl group, substituted alkyl group, aryl group, substituted aryl group), - formula (R +, R' + hydrogen,
selected from alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, adjacent R3, adjacent n'1 and R
, , R' are the same or different. It is a compound to which an alkylene oxide represented by m=2 to 6) is added.

Here, examples of the alcohol include methyl alcohol, ethyl alcohol, 5ec-butyl alcohol, hexyl alcohol, cyclohexyl alcohol, octyl alcohol, decyl alcohol, lauryl alcohol,
Cetyl alcohol, stearyl alcoholonopeicosanol, ceryl alcohol, myricyl alcohol, oleyl alcohol, 3-ethyl-6-undecanol, phenol, ρ-butylphenol, ρ-octylphenol, p-nonylphenol, benzyl alcohol, p-
Butylhensyl alcohol and the like are used.

Among these alcohols, long-chain aliphatic alcohols having 8 or more carbon atoms and p-alkyl-substituted phenols are preferable, and lauryl alcohol, stearyl alcohol, eicosanol, p-octylphenol, and p-nonylphenol are more preferable due to ease of handling. Particularly preferred.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide, oxetane, 3.3-
Examples include bis(chloromethyl)oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, oxepane, and the like. Among these alkylene oxides, ethylene oxide is particularly preferred, and from the viewpoint of easy availability, ethylene oxide and propylene oxide are particularly preferred.

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 of moles (n) of alkylene oxide added per mole of alcohol needs to be in the range of 1 to 1,000. From the viewpoint of the frictional properties of the polyacetal resin composition, it is preferable that n be large, while from the viewpoint of ease of production and purification, it is preferable that n be small. Based on both of these constraints, the most preferable range of n is 2 to 250
It is between.

Further, the number of moles (n) of alkylene oxide added per mole of alcohol can be easily determined by quantifying the hydroxyl group at one end of the produced adduct.

The graft copolymer of component (2) is an olefin copolymer (a) consisting of an α-olefin and a glycidyl ester of an α,β-unsaturated acid, and a repeating unit represented by the following general formula (Ilb). 0.5 to 25 parts by weight of a graft copolymer in which one or more of the polymers or copolymers (b) composed of Alkyl group, X is -GOO
CH3, -COOC285, -COOC4H9° Represents one or more groups. ).

Here, one of the polymers constituting the copolymer part of (a)
Examples of the α-olefin include ethylene, propylene, and butene-1, among which ethylene is most preferred.

In addition, other monomers constituting component (a), α, β-
The glycidyl ester of an unsaturated acid has the general formula (II a
) (Here, R represents hydrogen or a lower alkyl group.) Examples of the compounds include glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, etc., especially glycidyl methacrylate. Or preferable. The copolymer (a) can be obtained by copolymerizing an α-olefin (for example, ethylene) and an α7β-unsaturated acid glycidyl ester by a well-known radical polymerization reaction.

The composition of segment (a) is α-olefin 70-99
% by weight, 30-1% by weight of unsaturated acid glycidyl ester is preferred.

Next, the polymer or copolymer (b) to be graft-polymerized as a branched or crosslinked chain to this copolymer (a) is a polymer composed of repeating units represented by the above general formula (Il b > It is a copolymer obtained by copolymerizing more than one species, such as polymethyl methacrylate, polyethyl acrylate, polybutyl acrylate, poly(2-ethylhexyl) acrylate, polystyrene, polyacrylonitrile, polyacrylonitrile styrene copolymer, polyacrylic acid. Examples include copolymers of butyl and polystyrene.

These polymers or copolymers (b) are also prepared by radical polymerization of the corresponding vinyl monomers.

Component (2), which is a feature of the present invention, is not the copolymer (a) or the polymer (b) used alone, but the copolymer (a) and the polymer (b). at least one polymer
It is characterized by being a graft copolymer having a branched or cross-linked structure chemically bonded at points, and because it has such a graft structure, it cannot be obtained by blending (a) or (b) alone in cars. You will get a noticeable effect.

The blending amount of component (2) is 0.5 to 25 parts by weight.

If the amount is less than 0.5 parts by weight, the friction and wear characteristics of the polyacetal resin composition will deteriorate, and if it is more than 25 parts by weight, the mechanical properties of the polyacetal resin composition will deteriorate.

Furthermore, the compound used as the component (3) has the general formula % (in the formula, R4 and R6 are each selected from a hydrogen atom or an alkyl group with or without a substituent, and adjacent R4, adjacent ns and R4, R, are the same or different, R6 is a hydrocarbon group or an aliphatic or aromatic acyl group with or without a substituent, m' is an integer of 2 to 6, m' is 0 or 1 to 2000 2f! is an integer of 2f! One or more may be used in combination.

Component (3) can be obtained by adding alkylene oxide to alcohol or carboxylic acid.

Of the alcohols, carboxylic acids, and alkylene oxides, lauryl alcohol, stearyl alcohol, eicosanol, p-octylphenol, and p-nonylphenol are preferred as alcohols, and lauric acid and stearic acid are preferred as carboxylic acids, from the viewpoint of improved lubricity and ease of availability. , oleic acid and ricinoleic acid are preferred, and as the alkylene oxide, ethylene oxide and propylene oxide are preferred.

Furthermore, the number of moles of alkylene oxide added to alcohol or carboxylic acid is determined from the viewpoint of lubricity and ease of moldability, and the number of moles of alkylene oxide added in the alkylene oxide adduct of alcohol or carboxylic acid used for end-capping the base polymer is determined from the viewpoint of lubricity and ease of moldability. Preferably equal to or less than the number.

The blending ratio is selected within a range of 20 parts by weight or less.

If it exceeds 20 parts by weight, the mechanical properties of the composition will be significantly reduced. In view of lubricity, moldability, mechanical strength, etc., a range of 1 to 10 parts by weight is suitable.

The method for producing the composition of the present invention is not particularly limited, and may be, for example, a method of mixing pellets together using an ordinary extruder or a method of mixing in a powder state before pelletizing. do not have.

For example, the (1) component is a powdered polyacetal block polymer, the (2) component is a graft copolymer pellet or powder, and the (3) component is a formula <II+
＞ Liquid, solid or pasty,
Alternatively, it can be prepared by uniformly mixing powders using a Henschel mixer or the like.

This composition can be easily molded using an extruder, injection molding machine, or the like.

Furthermore, if necessary, conventionally known additives such as heat stabilizers, antioxidants, antistatic agents, flame retardants, inorganic fillers, ultraviolet inhibitors, pigments, dyes, etc. may be added to the composition of the present invention to impair the effects of the present invention. It may be added as long as it does not.

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

The blending method and measuring method used in this example are as follows.

(1) Blending method A Henschel mixer was used to mix the additives, and simultaneously with the mixing, 0.3 parts by weight and 0.15 parts by weight of a heat stabilizer for polyacetal and an antioxidant were added, respectively. Furthermore, after blending, using a twin-screw vented extruder (L/D ratio 32.0) set at 200°C, the screw rotation speed was 15.
1] rpm, discharge speed 3 kg/HR, resin temperature 205
The mixture was melted and kneaded at ℃ to form pellets.

Next, after drying this pellet at 80°C for 3 hours,
Using a molding machine with a mold temperature of 80°C and a cooling time of 20 seconds, the outer diameter was 211 mm, the inner diameter was 20 mm, and the depth was 17 mm.
A test piece was obtained by molding it into a cylindrical shape.

(2) Friction property measurement method This test piece was tested using a thrust type friction and wear tester [
manufactured by Toyo Seiki ■], mating materials: boriacetal copolymer (trade name, Asahi Kasei TENAC4510) and steel (S
The friction coefficient and amount of wear were measured for two types of 45C).

Coefficient of friction〉 The mating material is TENAC4510: The surface pressure is 2 kg/cm' The mating material is 545C: The surface pressure is 10 kg/cm2 and the linear velocity is 1.
Measurements were performed under conditions of 2 to 70 cm/sec, and the average coefficient of friction was determined.

Wear amount〉 Compatible material is TENAC4510: Linear speed 6 cm/sec
The mating material was 545C: measurements were performed under the conditions of a linear velocity of 60 cm/sec and a surface pressure of 2 kg/cm2 to determine the amount of wear.

(3) Flexural modulus Measured based on ASTM D790 measurement method.

Examples 1 to 5 Graft copolymerization in which polyacrylonitrile and styrene were graft-polymerized to ethylene-glycidyl methacrylate ester (85-15) copolymer using a polyacetal block polymer with polypropylene oxide stearyl ether introduced at one end as the base polymer. Table 1 shows the results of friction and wear characteristics obtained by adding 5 parts by weight of the polymer to 100 parts by weight of the polyacetal block polymer, and varying the amount of polyoxyethylene stearyl ether from 0 to 12 parts by weight.

Examples 6 to 10 Evaluations were carried out in the same manner as in Example 3, except that the graft copolymers shown in Table 2 were blended, and the results are shown in Table 2.

Example 1 Evaluations were carried out in the same manner as in Example 3, except that a polyacetal block polymer having polyethylene oxide stearyl ether introduced at one end was used as the base polymer, and the results are shown in Table 3.

Example 12.13 Evaluation was carried out in the same manner as in Example 3, except that the compound shown in Table 3 was blended as the alkylene oxide adduct, and the results are shown in Table 3.

Examples 14 to 18 As a graft copolymer, 0.5 to 20 parts by weight of LDPE-acrylonitrile/styrene copolymer obtained by graft copolymerizing acrylonitrile/styrene to ethylene-glycidyl methacrylate (85-15) was blended. The evaluation was carried out in the same manner as in Example 3, and the results are shown in Table 4.

Comparative Examples 1 to 4 A graft copolymer was blended with a general polyacetal homopolymer (trade name TeNAc5010) or polyacetal copolymer (trade name TENAC4510) as a base polymer and evaluated, but the results were inferior in friction and wear properties. The results are shown in Table 5.

Comparative Examples 5 to 8 The blending amount of the graft copolymer was 0 to 0 as shown in Table 6.
Evaluation was carried out in the same manner as in Example 3 except that the amount was 25 parts by weight and 26.0.30.0 parts by weight. 25 as shown in Table 6
If it exceeds the weight part, the frictional properties are excellent, but the bending modulus decreases significantly, and the original mechanical strength of polyacetal cannot be maintained.

Comparative Example 9 Evaluation was carried out in the same manner as in Example 3 except that 25 parts by weight of alkylene oxide adduct was blended. This can be attributed to the large amount of polyalkylene oxide added, but as shown in Table 6, the flexural modulus decreases, making it impossible to maintain the original mechanical strength of polyacetal.

Comparative Example 10 Example 3 Using LDPE (trade name Ace Polyethylene LD Grade L1850A) as the olefin copolymer
was added in place of the graft copolymer. This material had poor surface properties at the stage of making friction and wear test pieces for injection molding, so it was determined that it was not practical, and the evaluation was discontinued.

[Effect of the invention] As is clear from comparing Tables 1 to 4 and Table 5, a polymer alloy with a graft copolymer using a polyacetal block polymer in which polyalkylene stearyl ether is blocked at one end as a base polymer. The system has significantly improved friction and wear properties.

As described above, the feature of the present invention is that the friction and wear characteristics are significantly superior to conventional polyacetal lubricating grates.

Claims (1)

[Claims] 1. (1) One end of the linear polymer consisting of repeating oxymethylene units has the general formula <I> ▲There are mathematical formulas, chemical formulas, tables, etc.▼<I> (R_1, R' _1: selected from hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group, and adjacent R_1, adjacent R'_1 and R_1, R'_1 are each the same or different. R_2: alkyl group, substituted alkyl group , aryl group, substituted aryl group, m=2-6, n=1-
1,000 parts by weight of a polyacetal block polymer blocked with an alkylene oxide adduct to an alcohol represented by (2) an α-olefin and an α,β-
One or more of an olefin copolymer (a) consisting of a glycidyl ester of an unsaturated acid and a polymer or copolymer (b) composed of repeating units represented by the following general formula <IIb>, 0.5 to 25 parts by weight of chemically bonded graft copolymer with branched or crosslinked structure, ▲ Numerical formulas, chemical formulas, tables, etc. ▼〈II〉 (However, R_3 is hydrogen or lower alkyl group, X is -CO
OCH_3, -COOC_2H_5, -COOC_4H
_9, -COOCH_2CH(C_2H_5)C_4H
＿９、▲There are mathematical formulas, chemical formulas, tables, etc.▼、Indicates one or more groups selected from -CN. ) (3) General formula <III> ▲ Numerical formulas, chemical formulas, tables, etc. ▼ <III> (R_4 and R_5 in the formula are each selected from a hydrogen atom or an alkyl group with or without a substituent, and Matching R_4, adjacent R_5 and R_4, R_5 are each the same or different. R_6 is a hydrocarbon group or an aliphatic or aromatic acyl group with or without a substituent, m
' is an integer of 2 to 6, n' is an integer of 0 or 1 to 2000). . 2. 0.5 to 25 parts of component (2) to 100 parts by weight of component (1)
The polyacetal resin composition according to claim 1, wherein the polyacetal resin composition comprises parts by weight. 3. Olefin copolymer (a) constituting component (2)
The polyacetal resin composition according to claim 1, wherein is a glycidyl ester of ethylene and an α,β unsaturated acid.