JPH0662832B2 - Polyacetal resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyacetal resin composition having excellent lubricating properties.

[Prior Art] Polyacetal resins are excellent in mechanical strength, fatigue resistance, and electrical characteristics, and are used as engineering resins in gears, bearings,
Widely used for other mechanical parts and electrical parts. Further, the polyacetal resin is also excellent in self-lubricating property, and its properties are utilized in many applications.

However, it is not always sufficient for applications where self-lubrication is required, and improvement in lubrication characteristics is necessary.

As a conventional technique for improving lubrication characteristics, a method of lubricating a polyacetal resin by adding a lubricating oil agent such as engine oil by a special method or a method of adding an aliphatic ester such as glycerin or trimethylolpropane to the polyacetal resin is added. A method for improving lubricity, a novel polyacetal polymer having excellent lubricity (Japanese Patent Publication No. 59-15332), and the like have been proposed.

[Problems to be Solved by the Invention] However, these conventional techniques have problems that the general physical properties such as mechanical properties of the polyacetal resin are largely deteriorated and that the moldability is inferior. It wasn't possible.

The present invention provides a polyacetal resin composition having improved lubrication characteristics without deteriorating the mechanical properties or molding processability originally possessed by the polyacetal resin.

[Means and Actions for Solving the Problems] That is, according to the present invention, one end of a linear polymer composed of 100 parts by weight of polyoxymethylene and repeating oxymethylene units has the general formula (R ₁ : hydrogen, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, each of which is the same,
It can be different. Also, R bound to different carbon atoms
₁ may be the same or different. R _2: an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, m = 2 to 6, are blocked with an alkylene oxide adduct of the alcohol represented by n = 1 to 1,000), polyacetal 70-800 It is intended to provide a polyacetal resin composition which is composed of parts by weight and has excellent lubricating properties.

The present invention has succeeded in suppressing the deterioration of mechanical properties and molding processability of the polyacetal resin and remarkably improving the lubricating property of the polyacetal by adopting the above constitution.

The polyoxymethylene used in the present invention is an oxymethylene homopolymer and an oxymethylene copolymer consisting mostly of an oxymethylene chain, and homopolymerizes formaldehyde or a cyclic oligomer of formaldehyde, such as trioxane and tetraoxane, or the like. Is obtained by copolymerizing a copolymerizable comonomer with, and is stabilized against decomposition from the end,
Usually, stabilizers and antioxidants are added to these.

On the other hand, the polyacetal polymer used in the present invention,
In a linear polyacetal polymer composed of repeating oxymethylene units (-OCH _2- ), one end has the general formula (R ₁ : hydrogen, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, each of which is the same,
It can be different. Also, R bound to different carbon atoms
₁ may be the same or different. R ₂ : alkyl group, substituted alkyl group, aryl group, substituted aryl group, m = 2 to 6, n = 1 to 1,000) blocked with an alkylene oxide adduct to the alcohol, having the following structural formula It is united. The substituted alkyl group refers to groups such as phenylethyl, phenylbutyl, phenyllauryl, phenylstearyl, chlorobutyl and bromobutyl, and the substituted aryl group includes p-methylphenyl, p-ethylphenyl, p-butylphenyl, p-octyl. It refers to groups such as phenyl, p-laurylphenyl, p-stearylphenyl, p-chlorophenyl, p-bromophenyl.

(L: average degree of polymerization, R ₃ : hydrogen, alkyl group, substituted alkyl group, aryl group, substituted aryl group) The alkylene oxide adduct of alcohol which blocks one end of the polyacetal polymer is usually represented by the general formula R ₂ OH. (R ₂ : an alkyl group,
Alcohols represented by substituted alkyl groups, aryl groups, and substituted aryl groups) have the general formula (R ₁ : hydrogen, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, each of which is the same,
It can be different. It is a compound to which an alkylene oxide represented by m = 2 to 6) is added.

Here, as the alcohol, for example, 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, p-butylphenol, p-octylphenol, p-nonylphenol, benzyl alcohol, p-butylbenzyl 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 because they are easily available. Particularly preferred.

Examples of the alkylene oxide include ethylene oxide, propylene oxyt, butylene oxide, epichlorohydrin, sterine oxide, oxetane, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, 2-
Examples include methyltetrahydrofuran and oxepane. Among these alkylene oxides, ethylene oxide is particularly preferable, and ethylene oxide and propylene oxide are particularly preferable from the viewpoint of easy availability.

These alkylene oxides can be used alone or in combination of two or more. Alternatively, for example, it is possible to first add propylene oxide to alcohol, then add ethylene oiside to this, and further add propylene oxide.

The number of moles (n) of alkylene oxide added per mole of alcohol must be in the range of 1 to 1,000. Larger n is preferable, while smaller n is preferable from the viewpoint of ease of production and purification. With both of these constraints, the most preferred range for n is between 2 and 250.

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 composition ratio of the composition of the present invention is 100% polyoxymethylene.
70 parts by weight of the polyacetal polymer blocked with the alkylene oxide adduct of alcohol and 70 parts by weight, and more preferably 80 parts by weight to 300 parts by weight.

When the amount of the polyacetal polymer is less than 70 parts by weight, improvement of lubrication properties cannot be expected, and when it exceeds 800 parts by weight, mechanical properties are remarkably deteriorated, which is not preferable.

The composition of the present invention can be used alone or by adding a known lubricant.

Examples of the lubricant that can be added to the present invention include alcohol,
Alkylene oxide adducts with ethers and alcohols,
Compounds such as alkylene oxide adducts of carboxylic acids, terminal ethers of polyalkylene oxides, and diesters of polyalkylene oxides and carboxylic acids are preferably used.

The method for producing the composition of the present invention is not particularly limited, and may be either a method of kneading pellets using an ordinary extruder or a method of kneading in a polymerized powder state before pelletization.

Further, if necessary, a heat stabilizer, an antioxidant, an antistatic agent, a flame retardant, an inorganic filler, an ultraviolet protective agent and a pigment may be added to the composition of the present invention.

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

The friction coefficient and the wear amount of the molded product were obtained as follows.

<Friction coefficient> Using a thrust type friction and wear tester, the load is 2 kg / cm ² ,
The average friction coefficient was obtained by measuring under the linear velocity of 1.2 to 70 cm / sec. The smaller this value is, the better the lubricating property is.

<Abrasion amount> Using the tester, load is 2 kg / cm ² , linear velocity is 0.72 km / h
The amount of wear was calculated by measuring under conditions of r and running distance of 50 km. The smaller this value is, the better the lubricating property is.

Examples 1 to 4 100 parts by weight of polyoxymethylene homopolymer was kneaded at 200 ° C. with a 30 mm extruder to obtain a polyacetal polymer having the structure and amount shown in Table 1, and granulated to obtain a product. This was dried at 80 ° C. for 14 hours and then molded, and the friction coefficient and wear amount were measured.

The results are shown in Table 1. All showed good lubrication characteristics.

Examples 5-8 100 parts by weight of a polyoxymethylene copolymer obtained by copolymerizing trioxane and ethylene oxide was mixed with a polyacetal polymer having the structure and amount shown in Table 2 at 200 ° C. using a 30 mm extruder and granulated. Commercialized. 80 ° C
After being dried for 14 hours, it was molded and the friction coefficient and wear amount were measured.

The results are shown in Table 2.

All show good lubricating properties.

_{HOCH 2 CH 2 2 0 OC 1} 8 H 3 7 as the respective parts and the lubricant of the polyacetal polymer shown in Table 3 to 100 parts by weight Example 9-10 polyoxymethylene homopolymers _{(polyethylene} glycol monostearyl ether) Alternatively, 3 parts by weight of 1,4 butanediol dilaurate was blended and the same operation as in Example 1 was performed to measure the friction coefficient and the wear amount.

The results are shown in Table 3. All showed excellent lubrication characteristics.

Comparative Examples 1 to 4 100 parts by weight of a polyoxymethylene homopolymer or a polyoxymethylene copolymer obtained by copolymerizing trioxane and ethylene oxide and 100 parts by weight of the polyacetal polymer shown in Table 4 were blended, and the same as in Example 1, respectively. Various operations were performed to measure the friction coefficient and the amount of wear.

The results are shown in Table 4. In all the comparative examples, the lubrication characteristics were poor.

Comparative Example 5 Polyoxymethylene homopolymer 100 parts by weight of polyacetal polymer 850 parts by weight are blended, and the same operation as in Example 1 is performed, and the flexural modulus which is an index of mechanical properties (measurement method is ASTM-
According to D790. The larger this value, the better the mechanical properties)
Was measured. The results are shown in Table 5. The flexural modulus of the compositions used in Examples 3 to 4 is also shown in Table 5.
As shown in Table 5, the composition ratio of the polyacetal polymer is 80
When it exceeded 0 part by weight, the flexural modulus significantly decreased.

As is clear from Tables 1 to 4, by blending polyoxymethylene with the specific polyacetal polymer used in the present invention, the lubricating properties of the polyacetal resin are significantly improved.

[Effects of the Invention] Compared with conventional polyacetal resin compositions, the composition of the present invention can impart lubrication characteristics without impairing the mechanical properties or molding processability of polyacetal resins, and therefore requires engineered resin that requires lubrication characteristics. Can be used in a wider range.

Claims (1)

[Claims] 1. A linear polymer comprising 100 parts by weight of polyoxymethylene and repeating oxymethylene units has one end
General formula (R ₁ : hydrogen, an alkyl group, a substituted alkyl group, an aryl group, or a substituted aryl group, each of which is the same,
It can be different. Also, R bound to different carbon atoms
₁ may be the same or different. R _2: an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, m = 2 to 6, are blocked with an alkylene oxide adduct of the alcohol represented by n = 1 to 1,000), polyacetal 70-800 A polyacetal resin composition, characterized in that it comprises 1 part by weight.