JP3354714B2 - Polyacetal resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to abrasion resistance suitable for cams and lever parts, which has excellent friction and wear characteristics and does not peel off on the surface of molded products even under high load sliding conditions. The present invention relates to a polyacetal resin composition having:

[0002]

BACKGROUND OF THE INVENTION Polyacetal resins have well-balanced mechanical properties,
It is widely used in the fields of automobiles, electric / electronic products, etc. because of its excellent friction / wear resistance, chemical resistance, heat resistance, electric properties and the like. However, the required characteristics in such a field are gradually becoming higher, and as one example, further improvement in sliding characteristics such as a friction coefficient and a specific wear amount as well as general physical properties is desired. For the purpose of improving the sliding characteristics, addition of a fluororesin or a polyolefin-based resin to a polyacetal resin, and addition of a sliding improver such as a fatty acid, an aliphatic ester, and various synthetic lubricating oils have been performed. However, although the sole addition of lubricating oil has a certain effect in reducing the coefficient of friction and the specific wear, it has various difficulties such as difficulty in extrusion or bleeding in use. In addition, the addition of fluororesin or polyolefin resin improves the sliding characteristics to some extent, but these resins have poor compatibility with polyacetal resin, causing peeling on the molded product surface and under high load conditions. There is a problem that the wear characteristics are reduced. In addition, sufficient modification of the surface of the polyacetal resin requires the addition of a large amount of such a resin, which not only further reduces the abrasion resistance under high load conditions, but also significantly reduces the physical properties inherent to the polyacetal resin, especially the weld property. There has been a problem of lowering. Such a problem is caused when a polyolefin resin and a lubricant are added to and used in combination with a polyacetal resin (Japanese Patent Laid-Open No.
-99740) and improvement is desired.

[0003]

The inventors of the present invention have conducted intensive studies on such a point, and have found that a polyacetal resin is used in combination with an acid anhydride-modified polyolefin resin, a polyisocyanate compound or a modified product thereof, and a specific aliphatic ester. By adding the polyacetal resin composition, the abrasion resistance under high load is good, and the surface of the molded product does not peel even under the condition of high shear, and the sliding property is excellent. With success, they have completed the present invention. That is, the present invention relates to (A) 100 parts by weight of a polyacetal resin, and (B) an acid anhydride-modified polyolefin-based resin 1 to 100 parts by weight.
Polyacetal obtained by adding and blending 30 parts by weight and (C) 0.01 to 10 parts by weight of a polyisocyanate compound or a modified product thereof and (D) 0.1 to 10 parts by weight of a partial ester compound of a fatty acid having 16 or more carbon atoms and a polyhydric alcohol The present invention provides a resin composition.

[0004] The components of the present invention will be described below. The polyacetal resin in the present invention, a thermoplastic resin whose main component is polymeric compound which oxymethylene units (-CH ₂ O-) as the main repeating structural units, formaldehyde or trioxane, the tetraoxane like in a usual manner Homopolymerized, or a copolymer of two or more of these, or a monomer and a cyclic ether such as ethylene oxide, propylene oxide, oxacyclobutane, 1,3-dioxolan, β-propiolactone, γ-
A cyclic ester such as butyrolactone or a copolymer with a certain vinyl compound or the like is used as the component (A). Further, the polyacetal resin may have a part of its molecular terminal converted into an ether bond, an ester bond, or the like.

The component (B) of the present invention is an acid anhydride-modified polyolefin resin obtained by modifying a polyolefin resin with an acid anhydride. Examples of the polyolefin resin used herein include ethylene, propylene, butene, hexene, octene, nonene, decene, dodecene, and other homopolymers of α-olefins, or random, block or graft copolymers composed of two or more of these. Coalescing, or 1,4
Non-conjugated dienes such as hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 2,5-norbonadiene; conjugated diene components such as butadiene, isoprene and piperylene; α, β- such as acrylic acid and methacrylic acid.
Derivatives such as unsaturated acids or esters thereof, aromatic vinyl compounds such as acrylonitrile, styrene and α-methylstyrene, or comonomers such as vinyl esters such as vinyl acetate, vinyl ethers such as vinyl methyl ether, and derivatives of these vinyl compounds Examples thereof include random, block or graft copolymers containing one or more of the components, regardless of the degree of polymerization, presence or absence or degree of side chains or branches, copolymerization composition ratio, etc. From the viewpoint of dynamic characteristics, polyethylene, polypropylene, or a copolymer composed of two or more thereof is preferably used. Examples of the acid anhydride used for the modification include unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, and allyl succinic anhydride. Or one or more selected from derivatives thereof, and maleic anhydride is particularly preferably used. In addition, as a modification method, a method of adding an unsaturated carboxylic anhydride such as maleic anhydride or a derivative thereof during polymerization of a polyolefin resin and copolymerizing the same is generally used. It is not limited. Here, the compounding amount of both components is suitably from 0.1 to 20 parts by weight, preferably from 0.1 to 10 parts by weight, based on 100 parts by weight of the polyolefin resin. If the amount of the effective acid anhydride in the acid anhydride-modified polyolefin-based resin is too small, the affinity between the polyacetal resin and the polyolefin-based resin is not sufficiently improved. In such a case, gelation may occur, which may cause poor dispersibility or poor molding. The amount of the component (B) is 1 to 30 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the polyacetal resin (A). If the amount of component (B) is too low, the effects of the present invention are not sufficiently exerted. If the amount is too high, the properties of the polyacetal resin are impaired.

The polyisocyanate compound or its modified product used as the component (C) in the present invention is a compound having an iso (thio) cyanate group in the molecule.
A compound containing two or more iso (thio) cyanate groups in the molecule. (C) Examples of the component, for example, 4,4 '
-Diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Xylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1,5-naphthalenediisocyanate, or the corresponding diisothiocyanate, and their dimers, trimers, and isocyanate groups (-NCO) Although any of the compounds and the like protected in some form can be used, various properties such as the degree of discoloration of the melt treatment or the like, or in view of safety in handling, 4,4′-diphenylmethane diisocyanate,
Isophorone diisocyanate, 1,5-naphthalenediisocyanate, 1,6-hexamethylene diisocyanate,
Particularly preferred are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and their modified products (or derivatives) such as dimers and trimers. (C) The amount of component
(A) It is necessary to be in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the component. If the component (C) is less than 0.01 part by weight, the compatibility between the acid anhydride-modified polyolefin-based resin and the polyacetal resin is not sufficient, abrasion resistance is deteriorated, and gelling occurs when the amount exceeds 10 parts by weight. Is generated, and the fluidity and the resin properties are deteriorated, which is not preferable. Further, (C) as a catalyst for promoting the activity of the polyisocyanate compound or a modified product thereof, amines, or Sn, Zn,
By blending an organometallic compound containing a metal selected from Pb in any amount within a range that does not impair the physical properties of the present invention, the sliding characteristics and the appearance of the molded product surface are further improved.

Next, the carbon number of the component (D) used in the present invention
The partial ester compound of 16 or more fatty acids and a polyhydric alcohol is an ester of a non-esterified polyhydric alcohol having one or more hydroxyl groups. Examples of the fatty acids having 16 or more carbon atoms used in such esters include linear and / or branched unsaturated fatty acids such as palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid and montanic acid. Examples of the polyhydric alcohol include ethylene glycol, glycerin, pentaerythritol, butanediol, and the like. Of the partial ester compounds of fatty acids having 16 or more carbon atoms and polyhydric alcohols, particularly preferred are ethylene glycol monostearate and ethylene glycol monostearate in view of price, availability, friction and wear properties, and workability. Glycerin monostearate, glycerin monobehenate, butanediol monostearate, butanediol monobehenate and the like. In the present invention, one or more selected from these partial ester compounds are preferably used.
The amount of the partial ester compound (D) is 0.1 to 10 parts by weight based on 100 parts by weight of the polyacetal resin (A). If the amount is less than 0.1 part by weight, the effect of improving the slidability cannot be expected, and if the amount is more than 10 parts by weight, the properties of the polyacere resin as a base may be significantly impaired. Preferably, 0.5 to 5 parts by weight is blended.

When the composition of the present invention is melt-kneaded,
If necessary, antioxidants, ultraviolet absorbers, light protectants, phosphite stabilizers, peroxide decomposers, basic auxiliaries, nucleating agents, plasticizers, antistatic agents, flame retardants, coloring agents, Any amount of an additive such as a release agent may be blended within a range that does not impair the physical properties of the present invention. Next, the composition or molded article of the present invention can be easily prepared by a known method generally used as a conventional resin composition preparation method. For example, after mixing the respective components, a single-screw or twin-screw extruder kneads and extrudes to prepare pellets. Thereafter, a method of molding, once preparing pellets (master batch) having different compositions,
Any method can be used, such as a method of mixing (diluting) the pellets in a predetermined amount, subjecting them to molding, and obtaining a molded article having a desired composition after molding. In the preparation of such a composition, pulverizing part or all of the polyacetal resin as a base, mixing this with other components, and performing extrusion or the like is necessary for improving the dispersibility of the additive. This is the preferred method. The composition obtained by the present invention can be formed by a usual method.

[0009]

As described above, the characteristics and effects of the present invention are as follows: polyacetal resin is modified with acid anhydride-modified polyolefin resin and polyisocyanate compound or a modified product thereof.
Furthermore, by adding and blending a specific aliphatic partial ester, the compatibility between the acid anhydride-modified polyolefin resin holding the ester and the polyacetal resin is dramatically improved, and as a result, the abrasion resistance under high load is improved. An object of the present invention is to provide a polyacetal resin having excellent sliding characteristics, which is excellent and does not cause peeling on the surface of a molded product even under high shear conditions.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Examples 1 to 9 As shown in Table 1, as the component (A), a polyacetal resin (manufactured by Polyplastics Co., Ltd., trade name: Duracon),
A variety of acid anhydride-modified polyolefin resins as the component (B), various isocyanates as the component (C), and various partial esters as the component (D) are mixed in the amounts shown in Table 1 and set with a 30 mm twin screw extruder. Temperature 190 ° C, screw rotation speed 100r
The mixture was melt-kneaded at pm and pelletized. After drying at 80 ° C. for 2 hours or more, the pellets were molded into test pieces by an injection molding machine, and the following evaluation was performed. Table 1 shows the results. Comparative Examples 1 to 15 Polyacetal resin compositions having the compositions shown in Table 2 were prepared in the same manner as in Examples 1 to 9, and were similarly evaluated. Table 2 shows the results.・ Sliding characteristics Using a Suzuki type friction and wear tester, under 9kg load, linear velocity 5
Under running conditions of 0 mm / sec and 24 hours, a Suzuki-type test piece having a shape shown in FIG. 1 and a SUS metal pin (5 mmφ) were used.
× 5 mm) and the amount of abrasion were measured. -Surface condition of molded product A test piece for evaluation (50 mm x 50 mm x 1 mm: center pin gate type) was molded by changing the injection speed, and the state of peeling of the surface was evaluated in five stages. (Gate diameter: 1t) 1: Many peels on the whole molded product 2 ... There is a peel on the whole molded product 3 ... There is a peel only on the gate part 4 ... There is a minute peel only on the gate part 5 ... No peel ・ Weld strong elongation ASTM According to D-638, strength with and without weld (kg
f / cm ² ) and elongation (%) were measured.

[0011]

[Table 1]

(B) Polyolefin resin B-1 Maleic anhydride-modified polyethylene (maleic anhydride 1.0% by weight) B-2 Maleic anhydride-modified polyethylene (maleic anhydride 5.0% by weight) B-3 Maleic anhydride-modified polypropylene ( Maleic anhydride 1.0% by weight) B'-1 Polyethylene B'-2 Polypropylene B'-3 Polytetrafluoroethylene (C) Polyisocyanate IPDI Isophorone diisocyanate MDI 4,4'-Diphenylmethane diisocyanate (D) Aliphatic partial ester D- 1 Ethylene glycol monostearate D-2 Glycerin monostearate D-3 Glycerin monobehenate

[0013]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a sliding test piece used in an example.

[Description of Signs] 1 Suzuki-type test piece 2 SUS metal pin 3 Load

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 59/00-59/04

Claims (5)

(57) [Claims] (A) 1 to 30 parts by weight of an acid anhydride-modified polyolefin resin and (C) 0.01 to 30 parts by weight of a polyacetal resin and (C) a polyisocyanate compound or a modified product thereof.
A polyacetal resin composition comprising 10 parts by weight and (D) 0.1 to 10 parts by weight of a partial ester compound of a fatty acid having 16 or more carbon atoms and a polyhydric alcohol. 2. An acid anhydride-modified polyolefin resin as the component (B) is prepared by adding 100 parts by weight of a polyolefin resin to an acid anhydride of 0.1 part by weight.
2. The polyacetal resin composition according to claim 1, wherein the polyacetal resin composition is modified at from 20 to 20 parts by weight. 3. The polyacetal resin composition according to claim 1, wherein the acid anhydride-modified polyolefin resin (B) is a maleic anhydride-modified polyolefin resin. 4. The polyisocyanate compound of the component (C) or a modified product thereof is 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalenediisocyanate, 1,6-hexamethylene diisocyanate, or 2,4-triisocyanate. 2. A composition comprising at least one selected from the group consisting of diisocyanates, 2,6-tolylene diisocyanates and dimers and trimers thereof.
4. The polyacetal resin composition according to any one of claims 1 to 3. 5. The partial ester compound as component (D) is ethylene glycol monostearate, ethylene glycol monobehenate, glycerin monostearate, glycerin monobehenate, butanediol monostearate,
The polyacetal resin composition according to any one of claims 1 to 4, which is at least one selected from the group consisting of butanediol monobehenate.