JPH09286900A - Polyacetal resin composition for sliding material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sliding material composition excellent in sliding characteristics by blending and kneading a polyacetal resin with a modified polyolefin copolymer derived from a olefin, (meth)acrylic acid and an unsaturated carboxylic acid. SOLUTION: This composition is obtained by blending 100 pts.wt. polyacetal resin with 0.5-30 pts.wt. modified polyolefin copolymer or graft copolymer consisting of 44-99wt.% olefin units, 0.5-50wt.% (meth)acrylic acid (ester) units and 0.1-10wt.% unsaturated carboxylic acid (anhydride or derivative) units and melt kneading the blend. The sliding characteristics can be further improved by blending this composition with 0.5-10 pts.wt. lubricant comprising an ester of a 12C or higher aliphatic acid or alcohol. This composition has excellent characteristics in sliding not only on metals but also on resin members.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyacetal resin having excellent friction and wear characteristics, which is obtained by blending a specific modified polyolefin polymer and, if desired, a specific ester compound and melt kneading, The present invention relates to a polyacetal resin sliding material composition suitable for gears.

[0002]

BACKGROUND OF THE INVENTION Polyacetal resins have well-balanced mechanical properties,
It is widely used in the fields of automobiles, electric and electronic products, etc. because of its excellent friction and wear resistance, chemical resistance, heat resistance, electric properties, and the like. However, the required characteristics in such a field are gradually becoming more sophisticated, and as one example, further improvement in sliding characteristics as well as general physical properties is desired. Such a sliding property is an improvement in wear resistance in gear sliding. Generally, for the purpose of improving sliding properties, a fluororesin or a polyolefin resin is added to a polyacetal resin, and a lubricant such as a fatty acid, a fatty acid ester, silicone, or various mineral oils is added. Addition of fluororesin or polyolefin resin improves sliding properties to some extent, but since such different resins have poor compatibility with polyacetal resins, sliding properties under high surface pressure are insufficient and gear sliding Wear resistance is poor. In addition, there is also a problem in moldability that peeling is easily generated on the surface of the molded product and precipitates are easily generated in a molding die. In addition, addition of lubricating oil not only has various difficulties such as difficulty during extrusion or molding, or exudation during use, but it also inhibits the compatibility of different resins with polyacetal when used in combination with such different resins. However, there is a problem that wear resistance is significantly deteriorated. Particularly, in the case of gear materials such as cam gears and Andor gears, in which not only wear of the tooth surface but also sliding of the cam groove and the pin and sliding of the shaft material exist at the same time, the conventionally known method The wear resistance of the whole part is not sufficiently improved, and it is still insufficient from the viewpoint of molding processability and practicability, and in order to solve this problem, materials improved in these properties have been desired. .

[0003]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that a polyacetal resin is blended with a specific modified polyolefin-based copolymer and, if desired, a specific ester compound and melted. The present inventors have found that a composition having excellent sliding properties can be obtained by kneading, and have reached the present invention. That is, the present invention is (A)
Based on 100 parts by weight of the polyacetal resin, (B) (b-1) olefin unit, (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester unit, (b-3) unsaturated carboxylic acid and Composition for polyacetal resin sliding material obtained by blending 0.5 to 30 parts by weight of a modified polyolefin copolymer consisting of the acid anhydride unit and at least one selected from the group consisting of derivatives thereof and melt-kneading. And a gear part formed by molding the composition.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The components of the present invention will be described below. The polyacetal resin (A) used in the present invention is a polymer compound having an oxymethylene group (--CH ₂ O--) as a main constituent unit, a polyoxymethylene homopolymer, or an oxymethylene group as a main repeating unit, In addition to this, other structural units such as ethylene oxide and 1,3-
It may be a copolymer, a terpolymer or a block polymer containing a small amount of a comonomer unit such as dioxolane or 1,4-butanediol, and the molecule may have not only a linear structure but also a branched or crosslinked structure. Well again
It may be a known modified polyoxymethylene in which another organic group is introduced. The degree of polymerization is also not particularly limited as long as it has melt moldability.

Next, the modified polyolefin copolymer (B) blended with the polyacetal resin in the present invention will be described. The modified polyolefin-based copolymer of component (B) is
-1) olefin unit, (b-2) (meth) acrylic acid and /
Alternatively, it is a modified polyolefin copolymer comprising at least one selected from the group consisting of (meth) acrylic acid ester unit, (b-3) unsaturated carboxylic acid and its acid anhydride unit, and derivatives thereof. . Such (B) constituting the modified polyolefin-based copolymer (b-1) as the olefin unit, ethylene, propylene, 1-butene, 2-butene, isobutene, 3-methyl-1-butene, 2-methyl-2 -Butene, 1-hexene, 2,3-dimethyl-2-butene, 1-heptene, 1-octene, 1-nonene, 1-
2 to 20 unsaturated hydrocarbon monomers such as decene and 1-dodecene can be mentioned, and any of them is preferably used. (B) constitutes a modified polyolefin-based copolymer (b-2) (meth)
As acrylic acid and / or (meth) acrylic acid ester, acrylic acid, methacrylic acid, methyl acrylate,
Ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, etc. Α, β-unsaturated acids and their derivatives. Of such (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate are preferably available. can give. Next, at least one selected from the group consisting of (b-3) unsaturated carboxylic acids and their acid anhydride units, and their derivatives constituting the component (B) is maleic acid, citraconic acid, or itaconic acid. , Tetrahydrophthalic acid, nadic acid, methyl nadic acid, allyl succinic acid, and the like, and maleic anhydride, itaconic anhydride, citraconic anhydride and derivatives thereof. Maleic anhydride is preferably used in terms of availability and operation.

The (B) modified polyolefin copolymer of the present invention includes such (b-1) olefin unit, (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester unit, (b) -3) unsaturated carboxylic acid and its acid anhydride unit,
And a random, block, or graft copolymer containing at least one kind selected from the group consisting of derivatives thereof and one or more kinds respectively. In addition to such components, within a range that does not impair the effects of the present invention,
Non-conjugated dienes such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 2,5-norbonadiene, conjugated diene components such as butadiene, isoprene and piperylene, aromatic vinyl compounds such as α-methylstyrene Further, vinyl ether such as vinyl methyl ether and vinyl ether with polydiorganosiloxane may be blended. In the component (B) of the present invention, such (b
-1) Olefin unit, (b-2) (meth) acrylic acid and /
Alternatively, at least one selected from the group consisting of (meth) acrylic acid ester units, (b-3) unsaturated carboxylic acid and its acid anhydride units, and derivatives thereof, (B) a modified olefin-based copolymer As long as they are united, they can be used without any limitation depending on the polymerization method or purification method, and any of them is preferably used regardless of the degree of polymerization, presence or absence of side chains or branches, and degree. As a method for obtaining a modified polyolefin-based copolymer, for example, (b-1) a polyolefin composed of an olefin unit, (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester, (b-3 ) At least one selected from the group consisting of unsaturated carboxylic acids and acid anhydride units thereof, and derivatives thereof is reacted with a radical initiator such as a suitable organic peroxide in a solution state or a molten state by heating. In advance, a copolymer of the (b-1) olefin unit and the (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester unit is obtained. A method of graft-modifying at least one selected from the group consisting of a saturated carboxylic acid, an acid anhydride unit thereof, and a derivative thereof, (b-1) an olefin unit and (b-
2) At least one selected from the group consisting of (meth) acrylic acid and / or (meth) acrylic acid ester units, (b-3) unsaturated carboxylic acid and its acid anhydride units, and derivatives thereof are simultaneously added. Any method such as vinyl polymerization can be used and is preferably used. In particular, (b-1)
Component (b-2) component (olefin (meth) acrylic acid ester copolymer, selected from the group consisting of unsaturated carboxylic acid of component (b-3) and its acid anhydride unit, and derivatives thereof The method of graft-copolymerizing at least one of the above components is easy to control the composition ratio of each component and is preferably used.
In terms of availability, maleic anhydride-modified ethylene (meth) acrylic acid ester copolymer is preferably used, and particularly preferably maleic anhydride-modified ethylene ethyl acrylate,
Maleic anhydride-modified ethylene methyl acrylate, maleic anhydride-modified ethylene methyl methacrylate, and maleic anhydride-modified ethylene ethyl methacrylate are used.

The present invention relates to (b-1) olefin unit, (b-2)
At least one composition ratio selected from the group consisting of (meth) acrylic acid and / or (meth) acrylic acid ester units, (b-3) unsaturated carboxylic acid and its acid anhydride units, and derivatives thereof. Without limitation, any copolymer can be used, but (b-1) olefin units 45 to 99
% By weight, (b-2) (meth) acrylic acid and / or (meth)
Acrylic ester unit 0.5 to 50% by weight, (b-3) at least one kind selected from the group consisting of unsaturated carboxylic acid and its acid anhydride unit, and derivatives thereof 0.1 to 10% by weight
The (B) modified polyolefin-based copolymer consisting of ((b-1) + (b-2) + (b-3) = 100% by weight) is preferably used.

Particularly, when the amount of the effective (b-3) acid anhydride in the (B) modified polyolefin-based polymer is too small, the affinity between the polyacetal resin component and the polyolefin-based polymer is sufficiently improved. Therefore, the effects of the present invention cannot be obtained, and when the amount is too large, the physical properties to be improved such as sliding properties may be deteriorated. (b-3) Examples of acid anhydrides
0.1 to 5% by weight is preferable. (A) With polyacetal resin
The blending ratio with the (B) modified olefin-based copolymer is (A) 100 parts by weight of the polyacetal resin, and the (B) modified olefin-based copolymer is 0.5 to 30 parts by weight, preferably 0.5 to
20 parts by weight. If the amount of the component (B) is too small, the physical properties to be improved, such as sliding properties, are insufficient, and if it is too large, the wear resistance is rather reduced, which is not preferable.

The composition of the present invention has excellent properties even when it is used only with (A) a polyacetal resin and (B) a modified olefin copolymer, and in particular, it has a remarkable effect on slidability, molding processability and the like. However, if desired, the above (A)
Further effects can be obtained by blending the specific ester compound (C) in addition to the component (B).
Next, the (C) ester compound of the present invention will be described in detail. The (C) ester compound used in the present invention is an ester derived from a fatty acid having 12 or more carbon atoms and / or an ester derived from an aliphatic alcohol having 12 or more carbon atoms. As the fatty acid having 12 or more carbon atoms constituting such ester, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, isostearic acid,
Examples thereof include saturated fatty acids such as oleic acid, linoleic acid, linoleic acid, arachidic acid, behenic acid, lignoceric acid, cethylonic acid, montanic acid and melissic acid, unsaturated fatty acids, straight chain fatty acids and branched fatty acids, and 2-bromostearin. Acids, derivatives of such fatty acids such as 18-bromostearic acid and 18-hydroxystearic acid are preferably used. Examples of the alcohol that constitutes an ester with a fatty acid having 12 or more carbon atoms include n-octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, n-decyl alcohol, isodecyl alcohol,
Lauryl alcohol, myristyl alcohol, cetyl alcohol, 14-methylhexadecane-1-ol, stearyl alcohol, oleyl alcohol, 16-methylhexadecanol, 18-methylnonadecanol, 18-methylicosanol, docosanol, 20-methyl Heneicosanol, 20-methyldocosanol, tetracosanol, tetracosanol, hexacosanol, octacosanol, and other monovalent saturated and unsaturated aliphatic alcohols, straight-chain and branched alcohols, and the like, all of which are preferred used.

Further, examples of the aromatic alcohol constituting the ester include phenol, catechol and naphthol. Further, as the aliphatic polyhydric alcohol, ethylene glycol, propylene glycol,
1,4-butanediol, 1,5-pentanediol, 1,6
-Hexanediol, 1,2-octanediol, hexadecane-1,2-diol, octadecane-1,2-diol, icosane-1,2-diol, glycerin, trimethylolpropane, erythritol, pentaerythritol, sorbitol, 1, 2-cyclononanediol, 1,2
-Polyhydric alcohols such as cyclodecanediol and dipentaerythritol, tripentaerythritol, diethylene glycol, diglycerol, triglycerol, polyglycerol, polyethylene glycol, polypropylene glycol, etc., such polyhydric alcohol condensates, and succinic acid, Examples thereof include partial esters of polybasic acids such as adipic acid and such polyhydric alcohols, and any of them is preferably used.

As the aliphatic alcohol having 12 or more carbon atoms, lauryl alcohol, myristyl alcohol, cetyl alcohol, 14-methylhexadecan-1-ol,
Stearyl alcohol, oleyl alcohol, 16-methylhexadecanol, 18-methylnonadecanol, 18-
Saturated and unsaturated aliphatic alcohols such as methylicosanol, docosanol, 20-methylheneicosanol, 20-methyldocosanol, tetracosanol, tetracosanol, hexacosanol, octacosanol, straight chain and branched alcohols. And the like, and any of them is preferably used.

Examples of the fatty acid which constitutes the alcohol and the ester include laurin difference, tridecanoic acid, myristic acid, palmitic acid, stearic acid, isostearic acid,
Examples thereof include saturated fatty acids such as oleic acid, linoleic acid, linoleic acid, arachidic acid, behenic acid, lignoceric acid, cethylonic acid, montanic acid and melissic acid, unsaturated fatty acids, straight chain fatty acids and branched fatty acids, and 2-bromostearin. Acids, derivatives of such fatty acids such as 18-bromostearic acid and 12-hydroxystearic acid are preferably used.

Further, examples of the aromatic carboxylic acid include benzoic acid and phthalic acid. Examples of the aliphatic polybasic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecamethylenedicarboxylic acid, 1,14-tetradeca acid. Aliphatic polybasic acids such as methylenedicarboxylic acid, 1,16-hexadecamethylenedicarboxylic acid, 1,18-octadecamethylenedicarboxylic acid, trimellitic acid, maleic acid, fumaric acid, and derivatives of such carboxylic acids. Both are preferably used.

The above-mentioned esters consisting of carboxylic acid and alcohol are preferably used, but the following esters are more preferably used because they are easily available. That is, lauryl laurate, lauryl stearate,
Cetyl palmitate, isotridecyl stearate, oleyl oleate, stearyl stearate, isostearyl stearate, isostearyl isostearate,
Behenyl behenate, ethylene glycol distearate, glycerin monostearate, glycerin monobehenate, glycerin di, tristearate, trimethylolpropane triisostearate, pentaerythritol tetraisostearate, pentaerythritol tetrastearate, polyethylene Examples thereof include glycol dilaurate, polyethylene glycol distearate, diisotridecyl adipate and diisotridecyl phthalate, and one or more of such esters are preferably used.

In the present invention, the amount of the ester compound (C) added is 0.1 to 10 parts by weight. If the amount is less than 0.1 parts by weight, the original effect of the lubricant is difficult to be exhibited, and conversely, if the amount is more than 10 parts by weight, the properties of the base polyacetal are impaired, which is not preferable. It is more preferably 0.5 to 5 parts by weight. The composition of the present invention can further enhance stability by adding various known stabilizers. Further, in order to improve the physical properties depending on the intended use, various known additives may be further added. Examples of additives include various colorants, release agents (other than the above-mentioned lubricants), nucleating agents, antistatic agents, other surfactants, and different polymers (other than the above-mentioned graft copolymers). is there. If the composition of the present invention does not significantly deteriorate the performance of the composition, a fibrous, powdery or plate-like filler of inorganic, organic or metal is used.
It is also possible to use one kind or a mixture of two kinds.

Next, the composition of the present invention is easily prepared by a known method which is generally used as a conventional resin composition preparation method. For example, after mixing each component, kneading and extruding with a single-screw or twin-screw extruder to prepare pellets, once preparing pellets (master batch) having different compositions, and mixing (diluting) the pellets in a predetermined amount (dilution) Any method can be used. Further, in the preparation of such a composition, pulverizing part or all of each component, mixing this with other components, and performing extrusion or the like is a preferable method for improving the dispersibility of the additive. is there. In addition,
(C) When using an ester, a method of mixing a lubricant with each component in advance and impregnating it, then kneading the mixture and extruding the composition also facilitates preparation of the composition and improves workability and slidability. Is a preferable method.

[0017]

The composition for polyacetal resin sliding materials of the present invention is excellent not only in friction and wear characteristics, but also in sliding against resin as well as against sliding against metals, and various sliding parts in the AV and OA fields such as idler gears. Can be suitably used.

[0018]

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 17 and Comparative Examples 1 to 10 Various polyacetal resins (A) and modified polyolefin copolymers (B) shown in Table 1 and optionally various esters were mixed in the proportions shown in Table 1, and then biaxially mixed. The composition was melted and kneaded by an extruder to prepare a pelletized composition. Then, a test piece was prepared by injection molding using this pellet and evaluated. The results are shown in Table 1. For comparison, the same evaluations as those of the examples were carried out by using the polyolefin polymer not containing the component (B) or the polyolefin-based polymer not belonging to the component (B) of the present application, and optionally the lubricant (C). Table 2 shows the results. The methods for evaluating various physical properties in the examples are as follows. <Peeling and peeling of molded product> Test piece for evaluation
(mmt: φ1 mm center pin gate method) was molded, and the peeling condition of the surface was evaluated on a five-point scale. In addition, at the time of molding, the weighing property of each composition pellet (biteability into the screw of the molding machine) was evaluated, and shown in 5 stages.

Molding machine manufactured by Toshiba Corp. EPN80 Cylinder temperature (° C) = 200-200-170-150 Mold temperature (° C) = 85 Injection speed (m / min) = 1.0 Primary pressure (MPa) = 90 Secondary Pressure (MPa) = 60 Molding cycle (s) = 20 "-10" Molded product peeling 1 Many molded product peeled off 2 Many molded product peeled off 3 Only gate part peeled off 4 Gate part peeled off only 5 No peeling Moldability (measurable) 1 Cannot measure 2 Measuring time 31 seconds or more 3 Measuring time 21 seconds to 30 seconds 4 Measuring time 15 seconds to 20 seconds 5 Equivalent to polyacetal resin without additives (<15se
c) <Sliding property against steel> S by a journal type sliding tester
Sliding the friction shaft made of KS steel and the bearing made of test material,
The dynamic friction coefficient and the specific wear amount were evaluated. Sliding condition tester Journal type friction wear tester (manufactured by Toyo Seiki Co., Ltd.) Surface pressure 0.78kgf / cm ² Linear velocity 40.8cm / s (1200rpm) 48 hours sliding <wear resistance> Gear sliding tester Using the same material, a gear sliding test was conducted between the same materials, and the wear amount was evaluated from the weight change of the gear before and after sliding. Testing machine Gear fatigue testing machine (manufactured by Ono Sokki Co., Ltd.) Gear module 1.0 Gear ratio 23/54 Meshing tooth width 5mm Standard spur gear Test conditions Torque 0.55N ・ m, Rotation speed 600rpm, Repeat count 1.5 million times <Reciprocation Sliding test> As shown in FIG. 1, a polyacetal resin composition for evaluation was used for a moving plate material 1 (thickness: 3 mm), and a polyacetal resin (DURACON (manufactured by Polyplastics Co., Ltd.) was used for a pin material 2 of φ10. (Product name) 90-44)
The friction coefficient (μ) and the wear amount (mg) were measured by carrying out reciprocal sliding 20,000 times under the conditions of a load of 80 N, a sliding linear velocity of 5 cm / s and a stroke of 5 cm.

[0020]

[Table 1]

[0021]

[Table 2]

(A-1): Polyoxymethylene copolymer (melt index = 9.0 g / 10 min) (A-2): Polyoxymethylene homopolymer (melt index = 15.0 g / 10 min) (B-1): Ethylene / ethyl acrylate / maleic anhydride =
(b-1) :( b-2) :( b-3) = 94: 5: 1 (B-2): ethylene / ethyl acrylate / maleic anhydride =
(b-1) :( b-2) :( b-3) = 84: 15: 1 (B-3): Ethylene / ethyl acrylate / maleic anhydride =
(b-1) :( b-2) :( b-3) = 69: 30: 1 (B-4): Ethylene / ethyl acrylate / maleic anhydride =
(b-1) :( b-2) :( b-3) = 87: 10: 3 (B-5): ethylene / ethyl acrylate / maleic anhydride =
(b-1) :( b-2) :( b-3) = 84: 15: 1 (B-6): ethylene / acrylic acid / maleic anhydride = (b-1):
(b-2) :( b-3) = 84: 15: 1 (B-7): ethylene / methyl methacrylate / maleic anhydride = (b-1) :( b-2) :( b-3) = 84: 15: 1 (B'-1): Ethylene / maleic anhydride = (b-1): (b-3) = 9
9: 1 (B'-2): Ethylene / ethyl acrylate = (b-1): (b-2) =
85:15 (B'-3): Ethylene / methyl methacrylate = (b-1): (b-2)
= 85: 15

[Brief description of drawings]

FIG. 1 is a diagram showing a state of a reciprocal sliding test conducted in an example.

[Explanation of symbols]

 1 plate 2 pins

Claims (7)

[Claims] 1. (B) (b-1) olefin unit, (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester unit, and (b) -
3) 0.5 to 30 parts by weight of a modified polyolefin copolymer composed of an unsaturated carboxylic acid, an acid anhydride unit thereof, and at least one selected from the group consisting of derivatives thereof is mixed and melt-kneaded. Polyacetal resin sliding material composition. 2. The (B) modified polyolefin-based copolymer comprises:
(b-1) Olefin unit 45 to 99% by weight, (b-2) (meth) acrylic acid and / or (meth) acrylic acid ester unit
0.5 to 50% by weight, (b-3) at least one selected from the group consisting of unsaturated carboxylic acids and their anhydride units, and derivatives thereof 0.1 to 10% by weight ((b-1) + (b -2) + (b-3)
The composition for a polyacetal resin sliding material according to claim 1, which is a copolymer of 100% by weight). 3. The (B) modified polyolefin-based copolymer comprises:
(b-1) an olefin unit, (b-2) a copolymer composed of (meth) acrylic acid and / or (meth) acrylic acid ester units, and (b-3) an unsaturated carboxylic acid and its acid anhydride The composition for a polyacetal resin sliding material according to claim 1 or 2, which is a copolymer obtained by graft-modifying at least one selected from the group consisting of units and derivatives thereof. 4. The (b) the (meth) acrylic acid and / or (meth) acrylic acid ester unit constituting the (B) modified polyolefin-based copolymer is methyl acrylate, ethyl acrylate, propyl acrylate. The composition for a polyacetal resin sliding material according to any one of claims 1 to 3, which is one or more selected from the group consisting of, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Stuff. 5. An unsaturated carboxylic acid and its acid anhydride unit (b-3) which constitute (B) a modified polyolefin-based copolymer,
And at least one selected from the group consisting of derivatives thereof is maleic anhydride.
The composition for a sliding material of polyacetal resin according to the item. 6. The (C) ester compound further has a carbon number of
The composition for polyacetal resin sliding materials according to any one of claims 1 to 5, which comprises 0.5 to 10 parts by weight of an ester of 12 or more fatty acids and / or an ester of an aliphatic alcohol having 12 or more carbon atoms. 7. A gear component formed by molding the composition for a polyacetal resin sliding material according to claim 1. Description: