JPH03287619A - Polyacetal graft copolymer of excellent lubricity - Google Patents

Abstract

PURPOSE:To obtain the title copolymer having moldability inherent in polyacetal resin and excellent lubricity by forming a copolymer composed of a main-chain polymer comprising polyethylene and a side-chain polymer comprising polyoxymethylene by a specified production process. CONSTITUTION:A polyacetal graft copolymer having a number-average mol.wt. of 10,000-500,000 and excellent lubricity, wherein the main-chain polymer comprises polyethylene and the side-chain polymer comprises polyoxymethylene is obtained by homopolymerizing formaldehyde or copolymerizing formaldehyde with a cyclic ether in the presence of a modified polyethylene having at least one functional group selected from among OH, COOH, NH2, ester and alkoxy (e.g. vinyl alcohol-modified polyethylene or acrylic acid-modified polyethylene) as a mol.wt. modifier.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyacecool graft copolymer with excellent lubricating properties and a method for producing the same.

(Conventional technology) Polyacecool resin has excellent mechanical strength, fatigue resistance, and electrical properties, and is used as an engineering resin for gears, bearings,
Widely used in other mechanical and electrical parts. Polyacetal resin 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 lubricating properties.

Conventional techniques for improving lubricating properties include adding lubricating oil such as engine oil to polyacetal resin using a special method to achieve lubrication, and adding aliphatic esters such as glycerin and trimethylolpropane to polyacetal resin. There are known methods for improving lubricity.

(Problems to be Solved by the Invention) However, these conventional techniques have disadvantages such as a large decrease in general physical properties such as mechanical properties of polyacetal resin and poor moldability, and are not sufficiently developed. It wasn't a satisfactory method.

The present invention provides a polyacetal graft copolymer that has improved self-lubricating properties without deteriorating the physical properties or moldability inherent to the polyacetal resin.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polyacetal graft copolymer consisting of polyoxymethylene and polyethylene is different from conventional polyacetal polymers. They discovered that it has excellent lubricating properties that have never been seen before, and completed the present invention.

That is, the present invention includes: (1) Modified polyethylene containing at least one functional group of hydroxyl group, carboxyl group, amino group, ester group, or alkoxy group in the polymer is used as a molecular weight regulator, and formaldehyde is added to the polymer. A lubricant having a number average molecular weight between 10.000 and 500.000, obtained by homopolymerization or copolymerization of formaldehyde and a cyclic ether, with polyethylene as the backbone polymer and polyoxymethylene as the technical polymer. The present invention provides a polyacetal graft copolymer with excellent properties.

(1) As a molecular weight regulator, at least one hydroxyl group, carboxyl group, amino group,
Polyethylene with polyethylene as a backbone polymer, characterized by homopolymerizing formaldehyde or copolymerizing formaldehyde and a cyclic ether in the presence of modified polyethylene containing a functional group of either an ester group or an alkoxy group. Using oxymethylene as a branch polymer,
The present invention also provides a method for producing a polyacetal graft copolymer having a number average molecular weight between 10,000 and 500,000 and having excellent lubricity properties.

The polyacetal graft copolymer of the present invention is a graft copolymer composed of polyethylene and polyoxymethylene, and is a polyacetal graft copolymer having polyethylene as a trunk polymer and polyoxymethylene as a branch polymer.

Here, polyoxymethylene includes polyoxymethylene homopolymer and polyoxymethylene copolymer.

A polyoxymethylene homopolymer is a polymer consisting of repeating oxymethylene units +CH, ←.

A polyoxymethylene copolymer has an oxyalkylene unit: Ro + (C) in a chain consisting of oxymethylene units. 0+- 0 (Ro = selected from hydrogen, alkyl group, aryl group,
They may be the same or different.

m=2 to 6. ) is randomly inserted into the polymer.

The insertion rate of oxyalkylene units in the polyoxymethylene copolymer is 0.05 to 50 mol, more preferably 0.1 to 20 mol, per 100 mol of oxymethylene units.

Examples of oxyalkylene units include oxyethylene units, oxypropylene units, oxytrimethylene units,
There are oxytetramethylene units, oxybutylene units, oxyphenylethylene units, etc.

Among these oxyethylene units, from the viewpoint of improving the physical properties of the graft copolymer, oxyethylene units +
(cHi)go+ and oxytetraethylene unit -(
-(CHsudo+ is particularly preferred.

The segment that becomes the backbone polymer of the polyacetal graft copolymer of the present invention is polyethylene, and the polymer contains at least one functional group such as a hydroxyl group, a carboxyl group, an amino group, an ester group, or an alkoxy group. It is derived from modified polyethylene containing groups.

Modified polyethylene is polyethylene modified with a vinyl compound containing a hydroxyl group, carboxyl group, amino group, or alkoxy group in the presence of peroxide, or modified polyethylene with a vinyl compound containing a hydroxyl group, a carboxyl group, an amino group, or an alkoxy group. It is a compound obtained by copolymerizing a vinyl compound with a vinyl compound by a known method.

Confirmation that polyethylene has been modified with a vinyl compound having a functional group can be easily determined using general analytical equipment such as IR.

Furthermore, examples of vinyl compounds containing a functional group such as a hydroxyl group, a carboxyl group, an ester group, or an alkoxy group include vinyl alcohol, hydroxylethyl acrylate, hydroxylethyl methacrylate, hydroxylpropyl acrylate, and hydroxylpropyl methacrylate. , polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, allyl alcohol, glycerol monomethacrylate, acrylic acid, methacrylic acid, itaconic acid, methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, acrylic ester, Methacrylic acid ester, allylamine, vinyloxymethylamine, vinyloxyethylamine, vinyloxybutylamine, m-arylamine,
A typical example is dimethylaminostyrene.

Here, the polyacetal graft copolymer of the present invention is exemplified by the structural formula as follows.

HaJ\l\~X
Haqheno\-Y Y
Y or Y Y Y□; Polyethylene X: Modified group Y derived from a vinyl compound containing a hydroxyl group, carboxyl group, amino group, ester group, or alkoxy group; Polyoxymethylene (1) II); +CH bunt TCR.

Ro: selected from hydrogen, alkyl group, aryl group,
They may be the same or different.

m=2 to 6, R1; hydrogen, alkyl group, a, b: Integers representing a chain.

indicates that b oxyalkylene units are randomly inserted into eight oxymethylene units, and does not specify the distribution of oxyalkylene units in the polymer.

In the structural formula shown above, when R1 is a hydrogen atom, N
The graft copolymers having polyoxymethylene represented by ) and (I[[) have a hydroxyl group at the terminal and are unstable. Among these, a graft copolymer having a polyoxymethylene homopolymer is produced by esterifying the terminal hydroxyl group, etherifying it, urethanizing it, etc. using a known method.
After conversion to a stable group, it is put to practical use.

In addition, a graft copolymer having a polyoxymethylene copolymer (I [
For practical use.

The structure of the polyacetal graft copolymer of the present invention is confirmed by the following method.

That is, when a polyacetal graft copolymer is hydrolyzed in an acidic aqueous solution, the portion consisting of repeating oxymethylene units becomes formaldehyde, and the portion of oxyalkylene units inserted into the polyoxymethylene copolymer is expressed by the following formula %. Formaldehyde and alkylene glycol are analyzed and quantified using means such as gas chromatography and liquid chromatography.

Furthermore, the polyethylene contained in the graft copolymer becomes polyethylene (containing a modified group) having a hydroxyl group because the bond between polyethylene (containing a modified group) and polyoxymethylene is severed.

This polyethylene is precipitated from an aqueous solution. The precipitated polyethylene is analyzed and quantified using a conventional polymer analysis method.

The number average molecular weight of the polyacecool graft copolymers of the present invention is generally between 10,000 and 500,000. The lower limit of the number average molecular weight is restricted by the physical properties of the polyacetal graft copolymer, and the upper limit is restricted by the moldability of the polyacetal graft copolymer.

The number average molecular weight of the polyacetal graft copolymer is determined by the following method. That is, the number average molecular weight is 100.
If the number average molecular weight is 100 or less, use the osmotic pressure method or end group determination method, and if the number average molecular weight is 100,000 or more, use the weight average molecular weight determined by the light scattering method and gel permeation chromatography. The number average molecular weight is determined by combining it with the elution curve determined by the graph method (GPC method).

Note that the number of graft chains of polyoxymethylene, which is the technical polymer of the polyacetal graft copolymer of the present invention, is 1 to 10 in one molecule of the polyacetal graft copolymer from the viewpoint of mechanical properties of the polyacetal graft copolymer. Existence is preferably used.

Next, a method for producing the polyacecool graft copolymer of the present invention will be described.

The polyacecool graft copolymer of the present invention contains at least one functional group such as a hydroxyl group, a carboxyl group, an amino group, an ester group, or an alkoxy group in the polymer as a molecular weight regulator. It can be obtained by homopolymerizing formaldehyde or trioxane in the presence of modified polyethylene, or by copolymerizing formaldehyde and a cyclic ether.

The modified polyethylene used in the present invention is polyethylene modified with a vinyl compound having a functional group of hydroxyl group, carboxyl group, amino group, ester group, or alkoxy group in the presence of peroxide; Alternatively, a compound obtained by copolymerizing ethylene and a vinyl compound having the above functional group by a known method may be used.

Specific examples of modified polyethylene include vinyl alcohol modified polyethylene (Ml; 8.4 g/10 min, containing 3 hydroxyl groups), hydroquine ethyl acrylate modified polyethylene (Ml; 4.3 g/10 min, containing 10 hydroxyl groups),
Polypropylene glycol monoacrylate modified polyethylene (Ml; 14.3 g/10 min, containing 5 hydroxyl groups),
Polyethylene glycol monoacrylate modified polyethylene (Ml; 8.2 g/10 min, containing 4 hydroxyl groups), allyl alcohol modified polyethylene (Ml; 11°8 g
/l 0 min, containing 3 hydroxyl groups), isobutyl methacrylate modified polyethylene (Ml; 6.5 g/10 min, containing 3 ester groups), methyl methacrylate modified polyethylene (Ml; 7.3 g/10 min, containing 2 hydroxyl groups) Individual),
Vinyl butyl ether modified polyethylene (Ml i12
．． 9g/10 min, 3 alkoxy group-containing), acrylic acid modified polyethylene (M114.1g/10 min, 4 carboxyl group containing), methacrylic acid modified polyethylene (M
l ; 5.3 g/l 0 min, containing 4 carboxyl groups), vinyloxyethylamine-modified polyethylene (Ml
; 14.9 g/10 min, 3 amino groups), allylamine-modified polyethylene (Ml; 9.5 g/10 min,
(containing 3 amino groups), isobutyl methacrylate/hydroxylethyl methacrylate copolymer modified polyethylene (Ml; 6° 8 g/10 min, containing 6 hydroxyl groups), n-
Butyl acrylate/hydroxylethyl methacrylate copolymer modified polyethylene (Ml; 8.3g/10
representative examples include 4 hydroxyl groups).

It is desirable that these modified polyethylenes be purified by methods such as distillation, V&D, drying, etc. before being subjected to polymerization with formaldehyde or the like.

Moreover, these molecular weight regulators can be used alone, or two or more kinds can be mixed and subjected to polymerization.

In the polymerization reaction of the present invention, sufficiently purified formaldehyde and cyclic ale are used as starting materials.

For homopolymerization of formaldehyde, an anionic polymerization catalyst is used.
Further, a cationic polymerization catalyst is used for copolymerization of formaldehyde and cyclic ether.

The first group of cyclic ethers to be copolymerized with formaldehyde includes the formula -i; (Ro is selected from hydrogen, an alkyl group, and an aryl group, and each may be the same or different.

m=-2 to 6. ) There is an alkylene oxide represented by

Examples include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide, oxetane, 3,3-bis(chloromethyl)oxetane, tetrahydrofuran, oxepane, and the like. Among these alkylene oxides, ethylene oxide is particularly preferred.

The second group of cyclic ethers includes -i formula: There is a cyclic formal represented by

Examples include ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 15-bentanediol formal, and 1,6-hexanediol formal. Among these cyclic formals, ethylene glycol formal, diethylene glycol formal and
-butanediol formal is preferred.

Cyclic ether is 0.0 parts by weight per 100 parts by weight of starting materials.
3 to 100 parts by weight, more preferably 01 to 50 parts by weight are used.

The anionic polymerization catalyst and cationic polymerization catalyst used in the homopolymerization and copolymerization of the present invention are the following compounds.

Typical groups of anionic polymerization catalysts include alkali metals such as sodium and potassium; alkali metal complexes such as sodium-naphthalene and potassium-anthracene; alkali metal hydrides such as sodium hydride; alkaline earths such as calcium hydride. Metal hydrides; alkali metal alkoxides such as sodium methoxide and potassium t-butoxide; alkali metal carboxylates such as sodium caproate and potassium stearate; alkaline earth metal salts of carboxylates such as magnesium caproate and calcium stearate. ; Amines such as n-butylamine, diethylamine, trioctylamine, pyridine; Quaternary ammonium salts such as ammonium stearate, tetrabutylammonium methoxide, dimethyldistearylammonium acetate; tetramethylphosphonium propionate, trimethylbenzyl Examples include phosphonium salts such as phosphonium ethoxide; tetravalent organic tin compounds such as nitributyltin 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, alkyl trichloride, zinc chloride, vanadium trichloride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate, So-called Friedel compounds such as boron trifluoride coordination compounds such as boron trifluoride acetic anhydrate and boron trifluoride triethylamine complex compounds
Kraft-type compounds; inorganic and organic acids such as perchloric acid, acetyl perchlorate, hydroxyacetic acid, trichloroacetic acid, P-toluenesulfonic acid; triethyloxonium tetrafluoroborate, triphenylmethyl hexafluorophosphate, allyl Examples include complex salt compounds such as diazonium hexafluorophosphate and allyldiazonium tetrafluoroborate; alkyl metals such as diethylzinc, triethylargonium, and diethylargonium chloride.

These anionic polymerization catalysts and cationic polymerization catalysts are used in an amount of 0.0005 to 5 parts by weight based on 100 parts by weight of the starting material. Homopolymerization or copolymerization is carried out without solvent or in an organic medium.

Organic media that can be used in the present invention include:
Aliphatic and alicyclic hydrocarbons such as n-pentane, n-hexane, n-hebutane, n-octane, cyclohexane, and cyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; methylene chloride, chloroform, and There are halogenated aliphatic hydrocarbons such as carbon chloride, ethylene chloride, and trichloroethylene. These organic media may be used alone or in combination of two or more.

The modified polyethylene as a molecular weight regulator is used by being uniformly dissolved or dispersed in the reaction system.The concentration of the 9-molecule I regulator in the system is determined according to the molecular weight requirements of the desired polyacecool graft copolymer. can be easily determined by experiment.

The reaction temperature is usually set between -20 and 230°C, but preferably between 20 and 210°C in the case of no solvent, and between -10 and 120'C when using an organic catalyst.
It is more preferable.

There is no particular restriction on the reaction time, but it is set between 5 seconds and 300 minutes.

After a predetermined time has elapsed, a polymerization terminator is added to the reaction system to complete the homopolymerization or copolymerization. The obtained polymer is stabilized by removing unstable ends by hydrolysis or blocking unstable ends by a method such as esterification. The stabilized polyacecool graft copolymer is put into practical use with the addition of a stabilizer and the like.

(Examples) Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

The measurement items in the following examples are as follows.

(i) Ml 0.25 parts of 2.2-methylene-bis(4-methyl-5-L-butylphenol) and 6.60.50 parts of nylon to 100 parts of the polymer that has been terminally stabilized using acetic anhydride. was added and pelletized using a 50 mmφ extruder. The Ml of this pellet is ASTM-D I23B-
Measured according to 57T. Ml is a measure of molecular weight.

(i i) Lubrication properties; ■ Friction coefficient [Mating material: polyacetal homopolymer]
Using a Nilast type friction and wear tester, the load was 2 kg/d,
Measurements were performed under the conditions of a linear velocity of 1.2 to 70C1+/Sec, and the average coefficient of friction was determined.

■ Amount of wear [Mating material: Polyacetal homopolymer]
: Using the above testing machine, the load was 2 kg/cd, and the linear velocity was 0°7.
Measurements were made under the conditions of 2 parts m/hr and a mileage of 50 kl.
The amount of wear was determined.

The smaller the values of the friction coefficient and the amount of wear, the better the lubrication properties.

(iii) Tensile strength; A test piece is cut from a flat plate and measured according to ASTM-D 63B. The higher the tensile strength, the better the mechanical properties.

Example 1 (1) Substantially anhydrous formaldehyde gas was obtained by thermally decomposing sufficiently dehydrated and dried rose formaldehyde from Boace-Rgouf Ushihachi at 150° C. and passing it through a cooling trap several times. 1.0X10-' using 300g of formaldehyde gas per hour as a polymerization catalyst
mol/l of tetrabutylammonium acetate, vinyl alcohol modified polyethylene (M
l: 8.4 g/10 min, and this polymer has an average of 3 hydroxyl groups per molecule. Hereinafter, it will be abbreviated as EH. ) into 1.500 g of toluene containing 17.4 g/f. Simultaneously with the formaldehyde feed, 1.0×10-” mol/l of tetrabutylammonium acetate, 17.4 g/j! of EH
4 toluene containing at a rate of 1,500 g per hour.
Continuously supplied for hours.

Formaldehyde gas was also continuously supplied at a rate of 300 g per hour, during which time the polymerization temperature was maintained at 60°C. Toluene containing the obtained polymer was continuously extracted in proportion to the amount supplied, and the polymer was separated by filtration. After thoroughly washing the polymer with acetone, it was vacuum dried at 60°C.
.050 g of a white polymer was obtained.

(2) Approval of Boasse-Legouf fA.

200g of polyacetal graft copolymer obtained in (1)
0. Dispersed in 1.000 g of IN hydrochloric acid aqueous solution and heated at 90°C.
The mixture was heated for 2 hours. By this heating operation, the portion consisting of repeating oxymethylene units was completely hydrolyzed and returned to formaldehyde. On the other hand, under this condition, the molecular weight regulator does not undergo hydrolysis.

Next, this solution was neutralized with a 0.5N aqueous solution of caustic soda, and the EH precipitated in the aqueous solution was separated and recovered.
18.2g of EH was recovered.

When the Ml of this EH was measured, it was 8.4 g/10 minutes. This was the same as the Ml of EH used in the polymerization reaction (1).

In addition, after acetylating the polymer obtained in (1), terminal analysis and quantitative analysis using infrared absorption spectroscopy revealed that all the terminal groups were acetyl groups.
A value of 77 x 10-S moles of H,O chains was obtained. From this fact, M of the polyoxymethylene of the polymer obtained in (1)
It became clear that n was 3.9XIO'.

From the above analysis results, the polymer obtained in (1) has a structure in which three polyoxymethylenes (including modified groups) having the following structure are grafted onto polyethylene.

CH,CHOfCH,Osu13011H Furthermore, the EH content in this polyacetal graft copolymer is 9.1% by weight.

(3) A stabilizer was added to the polyacetal graft copolymer whose terminals had been stabilized using acetic anhydride. The physical properties and lubricating properties of this molded article are as follows.

Ml 0.4 (g/10 min) Tensile strength 5
90 (kg/cd) Coefficient of friction 0.11 Amount of wear 2B (mg) As described above, the polyacetal graft copolymer has excellent lubricating properties with little deterioration in mechanical properties.

Example 2 (1) Polypropylene glycol methacrylate modified polyethylene (Ml; 14°3 g/10 min, containing 5 hydroxyl groups, average degree of polymerization of polypropylene glycol ξ20, hereinafter, 16.0g of (abbreviated as PAE)
1.100 g of polymer was obtained by carrying out the same procedure as in Example except that /f toluene solution was used.

After acetylating this polymer, in trichlorobenzene, 1
Although it was subjected to an extraction operation at 50°C for 5 hours, no PAE was extracted. From this, it became clear that all PAE was inserted into the polymer.

(2) Hydrolyze and neutralize the polymer obtained in (1) in the same manner as in Example 1, and recover 16.8 g of PAE from the aqueous solution. did. When the Ml of this PAE was measured, it was 14.3.
g/10 minutes. This is the PA used for polymerization in (1).
It was the same as Ml of E.

In addition, after acetylating the polymer obtained in (1), terminal analysis and quantitative analysis using infrared absorption spectroscopy revealed that total terminal groups/CHz○ chain = 190 x 10-5 mol 1
Obtained the molar value. From this fact, it became clear that the Mn of the polyoxymethylene of the polymer (1) was 15.800.

From the above analysis results, the polymer obtained in fl) has a structure in which five polyoxymethylenes (including modified groups) having the following structure are grafted onto polyethylene.

Hz CH2-C Co (CH2CH○')-T-ii-tCH20S526 HI3 0 CH.

In addition, PAE in this polyacecool graft copolymer
The content is 8.4% by weight.

(3) Boi Ase - Lugu Ox's feet.

The polymer obtained in (1) has the following physical properties.

Ml 2.4 (g/10 min) Tensile strength 6
20 (kg/c11N) Friction coefficient 0.13 Wear IL 39 (mg) This polyacecool graft copolymer also has a desired molecular weight and excellent lubricating properties.

Example 3 (1) 300 g/hr of formaldehyde and 6 g/hr of ethylene oxide
8.7 as a molecular weight regulator at the rate of g/hr r
g/j2 vinyl methyl ether modified polyethylene (M
l; 6.9g/10 minutes, 2 pieces containing alkoxy, hereinafter referred to as B
It is abbreviated as E. ) was continuously fed into 1.500 g of toluene for 4 hours.

Toluene containing BE at the above concentration is also 1500g/h
It was continuously fed for 4 hours at a rate of r. In addition, 0.15 g of boron trifluoride dibutyl etherate was added as a polymerization catalyst.
hr rate for 4 hours, and the polymerization salinity was maintained at 60°C during this time.

The polymer was separated from toluene, then washed and dried to obtain 985 g of a polymer.

No BE was detected by hot decalin extraction of this polymer.

From this, it became clear that all BE was inserted into the polymer.

(2) First sighting of Boise Legouf f-person.

The polymer obtained in (1) was hydrolyzed under the same conditions as in Example 1,
The insertion rate of oxyethylene units in this polymer is 1.1
A result of 8 mol/100 mol·cHzo chain was obtained.

In addition, 9.6 g of BE was recovered from the aqueous solution in the same manner as in Example 1. The Ml of this BE was 6.9 g/10 min, which matched the molecular weight of the BE used as a molecular weight regulator.

After acetylating the polymer obtained in (1), terminal quantitative analysis was performed, and it was found that all terminal groups/CH! O chain = 120XIO-
'The value of 1 mole was obtained.

From this fact, it became clear that the Mn of the polyoxymethylene portion of the polymer (1) was 25.000.

From the above results, the polymer obtained in (1) has a structure in which two polyoxymethylenes (including modified groups) having the following structure are grafted onto polyethylene.

HI-CH OCI (20-6CHzOtrrpaCHzC11zOh
Furthermore, the BE content in this polyacetal graft copolymer is 4.8% by weight.

(3) Bo 1 Ace - Luguft Ox's feet.

The polymer obtained in (1) had the following physical property values.

Ml 0.9 (g/10 min) Tensile strength 5
80 (kg/c+6) Coefficient of friction 0.14 Amount of wear 45 (mg) This polyacetal graft copolymer also has a predetermined molecular weight, exhibits little deterioration in mechanical properties, and has excellent lubricating properties.

Comparative Example 1 Among the reagents used in Example 1, modified polyethylene (EH
), water, a known molecular weight regulator, was added at 8.7 x
Except for using a concentration of 10-2 g/l, all operations were carried out in the same manner as in Example 1 to obtain 1.090 g of polymer.

When the structure of the obtained polymer was analyzed using the same method as in Example 1, the Mn of the polymer was 36,000, and it had a structure of HO+cH, 111 OH.

The physical properties of the above polymer are as follows.

Ml 13 (g/10 min) Tensile strength 6
40 (kg/aa) Friction coefficient 0.39 Wear amount 1.120 (mg) The lubricating properties of this polymer are poor.

Examples 4 to 14 Polyacetal graft copolymers shown in Table 1 were produced using the starting materials and modified polyethylene (molecular weight regulator) shown in Table 1 (the structure of polyoxymethylene grafted to polyethylene is shown). ).

The physical properties of these polymers are also shown in Table 1.

In any of the examples, there was little deterioration in mechanical properties,
Polymers with excellent till gliding properties have been obtained.

Comparative Examples 2 to 3 Polyacetal polymers shown in Table 2 were produced using the starting materials and molecular weight regulators shown in Table 2.

The physical properties of these polymers are also shown in Table 2.

All of these polymers had poor lubricating properties.

(Effects of the Invention) The polyacetal graft copolymer of the present invention can provide molded articles with extremely superior self-lubricating properties compared to conventional polyacetal resins.

This excellent lubricating property is derived from the molecular structure of the polyacetal graft copolymer of the present invention, which contains polyethylene and has polyethylene as the main polymer and polyoxymethylene as the branch polymer.

(1 other person)

Claims (2)

[Claims] (1) Formaldehyde is homopolymerized using modified polyethylene containing at least one functional group of hydroxyl group, carboxyl group, amino group, ester group, or alkoxy group in the polymer as a molecular weight regulator. or a polyacetal with excellent lubricity properties, having a number average molecular weight between 10,000 and 500,000, which is obtained by copolymerizing formaldehyde and a cyclic ether, and has polyethylene as the main polymer and polyoxymethylene as the branch polymer. Graft copolymer. (2) Formaldehyde is added as a molecular weight regulator in the presence of modified polyethylene containing at least one functional group of hydroxyl group, carboxyl group, amino group, ester group, or alkoxy group in the polymer. Polyethylene as a backbone polymer and polyoxymethylene as a branch polymer, characterized by homopolymerization or copolymerization of formaldehyde and a cyclic ether, with a number average molecular weight between 10,000 and 500,000. A method for producing a polyacetal graft copolymer with excellent lubrication properties.