JP3181724B2 - 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 a novel polyacetal resin composition, and more particularly, to a good sliding property such as a slide fastener, a guide roller for running a tape, a sliding portion of a gear, a cam, a lever and the like. The present invention relates to a polyacetal resin composition having excellent slidability and abrasion resistance comprising a specific acrylic-modified polyorganosiloxane, which is suitable as a material for molded articles requiring abrasion resistance.

[0002]

2. Description of the Related Art Polyacetal resins are widely used in many fields because of their excellent mechanical strength, friction and abrasion resistance, chemical resistance, heat resistance, and electrical properties. Further improvement in slidability and wear resistance as well as general physical properties are desired.

As a method for improving the sliding characteristics of the polyacetal resin, addition of a fluororesin or a polyolefin resin, and addition of a lubricating oil such as a fatty acid, a fatty acid ester, a silicone oil, and various mineral oils are performed.

[0004] The addition of a fluororesin or a polyolefin resin improves the sliding properties to some extent, but these resins have poor compatibility with the polyacetal resin. It is easy to generate and the addition of lubricating oil has the effect of improving the sliding properties, but is still insufficient, and there are various problems such as impairment of moldability and bleeding during use.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to a polyacetal resin composition having improved problems as described above, that is, it has excellent sliding properties and good appearance of molded articles due to good compatibility of compounding agents. The present invention has been made to provide a novel polyacetal resin composition having no problem with respect to the durability and the effect durability.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the object can be attained by blending a specific acrylic-modified polyorganosiloxane, and reached the present invention. did.

[0007] That is, the present invention has solved the above-mentioned problems, and is based on (1) 100 parts by weight of polyacetal resin, and (2) general formula 1

Embedded image [Wherein R ¹ , R ² and R 3 independently represent a hydrocarbon group having 1 to 20 carbon atoms or a halogenated hydrocarbon group, Y represents a radical reactive group or an organic group having a —SH group, and Z ¹ and Z ² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a formula —SiR ⁴ R ⁵ R ⁶ (R ⁴ and R ⁵ are each independently a carbon atom having 1 carbon atom,
To 20 hydrocarbon groups or halogenated hydrocarbon groups;
⁶ represents a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, or a radical reactive group or an organic group having a -SH group. ), M is a positive integer of 10,000 or less, and n is an integer of 1 or more. And CH ₂ ＣC (R ⁷ ) COOR ⁸ (wherein R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ is an alkyl group, an alkoxy-substituted alkyl group, or a cycloalkyl group) or an aryl group.) represented by (meth) acrylic acid esters 70% by weight or more and this is copolymerizable with hydro
Xyl group-containing unsaturated monomer 30% by weight or less (excluding 0)
A polyacetal resin composition comprising 0.1 to 20 parts by weight of an acryl-modified polyorganosiloxane obtained by graft copolymerization of a mixture with the above at a weight ratio of 5:95 to 95: 5. Things.

Hereinafter, the present invention will be described in detail. In the present invention, as the polyacetal resin, any of a polyacetal homopolymer and a polyacetal copolymer having a main chain composed mainly of oxymethylene chains can be used. Further, those obtained by modifying polyacetal by crosslinking or graft copolymerization by a known method can also be used.

In the production of the acryl-modified polyorganosiloxane used in the present invention, the polyorganosiloxane represented by the general formula 1 is used as a raw material. R ¹ , R ² and R ³ in the general formula 1 are independently exemplified by alkyl groups such as methyl group, ethyl group, propyl group and butyl group, and aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group. A monovalent hydrocarbon group having 1 to 20 carbon atoms, or a group in which at least one hydrogen atom bonded to a carbon atom of these groups is substituted with a halogen atom. Y is a vinyl group, an allyl group,
a radical reactive group exemplified by a γ-methacryloxypropyl group, or an exemplified by a γ-mercaptopropyl group
Represents an SH group-containing organic group. Z ¹ and Z ^{2 each} independently represent a hydrogen atom, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or a compound represented by the formula —SiR ⁴ R ⁵ R ⁶ (R ⁴ , R ⁵
Independently monovalent hydrocarbon radicals R ¹ to R ³ carbon atoms exemplified by 20, or a monovalent halogenated hydrocarbon group having a carbon number of 1-20, R ⁶ is 1 to carbon atoms 20 represents a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, or an organic group having a radical reactive group exemplified by Y or a -SH group. ) Represents a triorganosilyl group. m represents a positive integer of 10,000 or less, and n represents an integer of 1 or more. In one molecule, each of R ^{1 to} R ⁶ and Y may be the same or different.

[0010] Such a polyorganosiloxane can be produced by a known method. For example, it can be produced by using a chain or cyclic low-molecular-weight polyorganosiloxane having the above-mentioned group or an alkoxysilane and combining means of hydrolysis, polymerization and equilibration. Hydrolysis, polymerization, and equilibration can be performed in a state of being emulsified and dispersed in water by a known technique. m and n are as described above, but in the range of 500 <m <8,000 and 1 <n <500 in view of the characteristics of the polyorganosiloxane or the graft copolymer of the polyorganosiloxane and the (meth) acrylate monomer. It may be adjusted by a known method such as mixing of raw materials. The siloxane chain may have some branches.

The (meth) acrylic acid ester represented by the general formula 2 as another raw material is methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tertbutyl (meth) acrylate,
Alkyl (meth) acrylates such as pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and methoxyethyl (meth) acrylate Examples thereof include alkoxyalkyl (meth) acrylates such as acrylate and butoxyethyl (meth) acrylate, cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, and aryl (meth) acrylates such as phenyl (meth) acrylate. Can be used alone or in combination of two or more.

The (meth) acrylate can be used in admixture with one or more hydroxyl group-containing unsaturated monomers copolymerizable therewith . However, from the viewpoint of characteristics, the content of the (meth) acrylic acid ester is preferably 70% by weight or more, and the amount of the hydroxyl group-containing unsaturated monomer copolymerizable therewith is preferably 30% by weight or less (excluding 0%) . Examples of the copolymerizable unsaturated monomer having a hydroxyl group include 2
-Hydroxyethyl (meth) acrylate, 2-hydro
Xypropyl (meth) acrylate and the like.

In order to improve the slidability and abrasion resistance, it is advantageous for the molded article to have a high surface hardness. Therefore, when a large amount of an acrylic-modified polyorganosiloxane obtained by graft copolymerization is blended with a polyacetal resin, , from among the (meth) acrylic esters and copolymerizable therewith hydroxyl group-containing unsaturated monomer represented by the general formula (2), a high monomer glass transition temperature of their homopolymers (Tg) It is preferable to select

The above-mentioned polyorganosiloxane, a (meth) acrylate and a copolymerizable hydroxy
When an acrylic-modified polyorganosiloxane is produced by graft copolymerization using a mixture of a sil group-containing unsaturated monomer, a polyorganosiloxane: (meth)
The weight ratio of the total amount of monomers such as acrylic acid ester is 5:95 to 95: 5. If the amount of the polyorganosiloxane is too large, the compatibility with the polyacetal resin deteriorates, and the appearance is impaired. If the amount is too small, the effect of improving the slidability and wear resistance is insufficient.

[0015] The graft copolymerization can be carried out by a known technique. For example, polyorganosiloxane and (meth) acrylic acid ester and copolymerizable hydro
Graft copolymerization occurs when a mixture of xyl group-containing unsaturated monomers is emulsified and dispersed in water and polymerized in the presence of a radical polymerization initiator. Emulsifiers and radical polymerization initiators used in this method may be those known for emulsion polymerization. After completion of the polymerization, an acryl-modified polyorganosiloxane which is a graft copolymer is obtained by salting out, filtration, washing with water and drying.
In this emulsion graft copolymerization method, if the polyorganosiloxane is produced in a state of being emulsified and dispersed in water as described above, the resulting polyorganosiloxane emulsion can be used as a raw material for graft copolymerization. .

The amount of the acryl-modified polyorganosiloxane is 0.1 to 20 parts by weight based on 100 parts by weight of the polyacetal resin. If the amount is less than 0.1 part by weight, the appearance is good, but the slidability is insufficient, and If it exceeds, the slidability is good, but the appearance deteriorates, which is not preferable.

In the composition of the present invention, in addition to the above-mentioned components, stabilizers, coloring agents, release agents, antistatic agents and the like which are usually used for polyacetal resins can be added. The type and amount of these can be appropriately selected depending on the use, required characteristics, workability, cost, and the like.

The composition of the present invention can be easily prepared by mixing the above-mentioned components and using a generally known method. For example, after mixing each component, a method of kneading and extruding with a single-screw or twin-screw extruder to form pellets, once creating a master batch having a different composition, mixing it in a predetermined amount and molding, and simultaneously forming the target composition And how to
Either can be adopted.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described based on embodiments.
All parts in the examples are parts by weight, and% represents% by weight. (Production of polyorganosiloxane emulsion) 1500 parts of octamethylcyclotetrasiloxane, 1.2 parts of methacryloxypropylmethylsiloxane and 1500 parts of pure water were mixed, and 15 parts of sodium lauryl sulfate and 10 parts of dodecylbenzenesulfonic acid were added thereto. The mixture was then emulsified by stirring with a homomixer, and then passed twice through a homogenizer at a pressure of 3000 psi to form a stable emulsion. Then
After heating at 70 ° C for 12 hours, cooling to 25 ° C and aging for 24 hours, adjust the pH of this emulsion to 7 using sodium carbonate, blow nitrogen gas for 4 hours and vaporize by steam distillation. The volatile siloxane was distilled off, and then pure water was added to adjust the nonvolatile content to 45%.
An emulsion of polyorganosiloxane containing 03 mol% (hereinafter abbreviated as E-1) was obtained.

A polyorganosiloxane emulsion E-2 was obtained in the same manner as in E-1 except that 98.4 parts of mercaptopropylmethylsiloxane was used instead of 1.2 parts of methacryloxypropylmethylsiloxane.

(Production of Acrylic-Modified Polyorganosiloxane) In a reaction vessel equipped with a stirrer, a condenser, a thermometer and a nitrogen gas inlet, 1110 parts of the polyorganosiloxane emulsion E-1 obtained above (polyorganosiloxane content:
500 parts) and 1053 parts of pure water, and the inside of the vessel was adjusted to 10 ° C. under a stream of nitrogen gas. Then, 1.0 part of t-butyl hydroperoxide, 0.5 part of L-ascorbic acid, and 7 parts of ferrous sulfate 7 were added.
To the mixture, 0.002 parts of hydrate was added, and a mixture of 210 parts of methyl methacrylate and 4.5 parts of 2-hydroxyethyl methacrylate was added dropwise over 3 hours while maintaining the inside temperature at 10 ° C. After the addition, stirring was continued for 1 hour. To complete the reaction. The obtained copolymer emulsion has a solid content of 30%.
Met. Then, 1000 parts of this emulsion was charged into a container equipped with a stirrer and heated to 60 ° C.
A solution prepared by dissolving 92 parts in 563 parts of pure water was added to precipitate an acryl-modified polyorganosiloxane, which was repeatedly filtered and washed with water, dried at 60 ° C., and dried at 60 ° C. (hereinafter abbreviated as P-1). ) Got.

Further, instead of 1110 parts of polyorganosiloxane emulsion E-1 and 1053 parts of pure water, 477 parts of polyorganosiloxane emulsion E-2 (214.5 parts of polyorganosiloxane) and 1400 parts of pure water were charged, and methyl was added. Instead of a mixture of 210 parts of methacrylate and 4.5 parts of 2-hydroxyethyl methacrylate, methyl acrylate 97
Parts, ethyl acrylate 50 parts, methyl methacrylate 3
An acrylic-modified polyorganosiloxane P-2 was obtained in the same manner as in P-1 except that a mixture of 43 parts and 10 parts of 2-hydroxyethyl methacrylate was dropped.

Example 1 100 parts of a polyacetal resin (Homopolymer manufactured by Asahi Kasei Corporation, trade name: Tenac 5010) was mixed with 5 parts of an acryl-modified polyorganosiloxane P-1 and then melt-kneaded with a twin-screw extruder to form pellets. Was prepared. Next, a test piece was prepared by injection molding using the pellet and evaluated. Table 1 shows the results.

Examples 2 and 3 and Comparative Examples 1-2 In the same manner as in Example 1, test pieces were prepared with the composition (type and amount of components) shown in Table 1 and evaluated. Table 1 shows the results.

The evaluation items and evaluation methods are as follows. 1. Coefficient of friction Using a Suzuki type friction and wear tester, surface pressure 10 kg / cm ² , linear velocity 10
The coefficient of friction was measured at cm / sec. Steel plate S4 as mating material
5C and 100 parts of the polyacetal resin prepared in Comparative Example 1,
A resin plate composed of 5 parts of calcium carbonate was used. 2. Surface state of molded article The surface state of the test piece was evaluated visually and by touch.

[0026]

[Table 1]

[0027]

According to the present invention, there has been provided a novel polyacetal resin composition having excellent slidability and capable of obtaining a molded article whose appearance is remarkably improved due to good compatibility of a compounding agent.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-18444 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 59/00-59/04

Claims (1)

(57) [Claims] (1) 100 parts by weight of polyacetal resin (2) General formula 1 [Wherein R ¹ , R ² and R 3 independently represent a hydrocarbon group having 1 to 20 carbon atoms or a halogenated hydrocarbon group, Y represents a radical reactive group or an organic group having a —SH group, and Z ¹ and Z ² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a formula —SiR ⁴ R ⁵ R ⁶ (R ⁴ and R ⁵ are each independently a carbon atom having 1 carbon atom,
To 20 hydrocarbon groups or halogenated hydrocarbon groups;
⁶ represents a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, or a radical reactive group or an organic group having a -SH group. ), M is a positive integer of 10,000 or less, and n is an integer of 1 or more. And CH ₂ ＣC (R ⁷ ) COOR ⁸ (wherein R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ is an alkyl group, an alkoxy-substituted alkyl group, or a cycloalkyl group) or an aryl group.) represented by (meth) acrylic acid ester 70 wt% or more copolymerizable therewith hydro
Xyl group-containing unsaturated monomer 30% by weight or less (excluding 0)
A polyacetal resin composition comprising 0.1 to 20 parts by weight of an acrylic-modified polyorganosiloxane obtained by graft copolymerization of a mixture of the above with a mixture in a weight ratio of 5:95 to 95: 5.