KR0140093B1 - Polyacetal resin composition - Google Patents

Abstract

The present invention relates to a polyacetal resin composition, and more particularly to a polyacetal resin composition excellent in wear resistance and noise characteristics.

The present invention relates to (A) 99-80 parts by weight of a polyacetal resin, (B) a compound (A) having a reactive group, a monomer (B) copolymerizable with a reactive monomer (A), (A) and (B 0.05-20 parts by weight of (C) modified silicone, based on 100 parts by weight of a composition composed of 1.0-20 parts by weight of a reactive copolymer prepared by appropriately copolymerizing a vinyl monomer (C) capable of copolymerizing with a copolymer of Within 10 parts by weight of the lubricant is added, but the molar ratio of the mole number of the reactive functional group in the component (B) and the component (C) is 1: 1 to 1: 4.

The composition of the present invention configured as described above has a continuous abrasion resistance characteristics and at the same time prevent defects such as leakage of additives or contamination.

Description

Polyacetal Resin Composition Having Semi-reciprocal Penetration Crosslinking Structure

The present invention relates to a polyacetal resin composition having a semi-reciprocal crosslinked crosslinked structure, and more particularly, to a polyacetal resin composition having continuous frictional wear resistance and no lubricant leakage or contamination.

Polyacetal resins are widely used in various electrical and electronic products and automotive fields because they have excellent physical properties in mechanical properties, frictional wear properties, creep resistance, chemical resistance and electrical properties. However, in the field where excellent driving characteristics such as various gears and cam bushings are required, products having improved frictional wear resistance and low noise characteristics are required than conventional products. The driving characteristics refer to characteristics in which dynamic friction coefficient, non-wearing amount, noise, PV limit value, etc. are combined in consideration. Conventional techniques for imparting lubricity and wear resistance to polyacetal resins are as follows.

1) A technology for incorporating a variety of silicone polymers as disclosed in Korean Patent Publications 91-7336, 91-7334, US Patent Nos. 3,491,048 and 791,386, etc.

2) incorporating aliphatic alcohols and their esters and metal soap systems alone or in combination as disclosed in Japanese Patent Application Laid-Open No. 48-37572, or incorporating synthetic oil and mineral oil alone or in combination as in Japanese Patent Application Laid-Open No. 75-10841; Technology

3) Technology to improve wear resistance by kneading fluorine resin with polyacetal resin as in Japan Special Public Office 46-30590

4) Technology to improve frictional wear characteristics using ultra high molecular weight polyethylene and polyacetal resin as in Japan Special Office 46-30590

However, in the case of 1), the affinity between the silicone polymer and the polyacetal is not good, so it is easy to cause processing problems due to friction loss with the inner wall of the cylinder when the excessive amount is injected. There is a problem that bleed out occurs.

In the process of adding various synthetic oils and mineral oils inside the resin, the technology of 2) lowers the thermal stability of the substrate due to thermal decomposition of lubricants whose thermal properties are unstable, or discolors due to the leakage of carbonization or decomposition products. There is a problem that contamination is likely to occur. In addition, the aliphatic compounds used herein are effective under mild driving conditions, but under severe conditions, the oil film formed on the surface is easily damaged, and thus there is a problem that the wear characteristics are not properly exhibited. The method of 3) and 4), which is in the form of filling inside the resin and exhibits abrasion resistance function, maintains driving durability even at a relatively high speed and high load, but the dispersibility of the composition filled in the resin is uneven, resulting in appearance and mechanical properties. There is a bad problem.

In order to improve the problems as described above, that is, the outflow of oil or poor processability and thermal stability, Japanese Patent Application No. 46-41456, US Patent No. 4,041,002, etc., use an olefin or an olefin and a vinyl copolymer together with various lubricants. Although the olefin-based polymer used in this technology is incompatible with acetal, it exhibits a distinct phase separation phenomenon under high shear rate, peeling phenomenon on the surface of the molded article, and another accompanied by a significant decrease in physical properties. The problem is caused.

Korean Patent Laid-Open Publication No. 91-4735 discloses a method of adding a lubricant to a polyacetal resin by containing a copolymer composed of an olefin polymer and a vinyl or ester polymer.

The copolymer used in this technology has the advantage of good compatibility with acetal and there is no peeling phenomenon during low-speed injection molding. However, this method also has a problem that the copolymer and the lubricant are separated from each other and peeled off at a high speed injection, and contamination and frictional property deterioration due to surface leakage of the lubricant is caused during long-term driving. As a result, there is a problem that the ability to withstand the molded article even under high speed and high loads.

The present invention is to solve the above problems, and to provide a polyacetal resin composition having excellent frictional wear resistance and low noise characteristics, but no degradation of mechanical properties and no leakage or contamination of additives.

As a result of repeated studies in order to achieve the above object, the present inventors have found that a semi-reciprocal permeation crosslinked structure is formed by mixing and reacting a specific reactive polymer polymer, a modified silicone including a reactor therewith, and a conventional lubricant. At the same time, it has been found that defects such as leakage of additives and contamination are prevented while having frictional wear resistance.

Hereinafter, the present invention will be described in detail.

The present invention,

A) 99-80 parts by weight of polyacetal resin (abbreviated below),

B) A compound (a) having a reactive group, a monomer (b) copolymerizable with a reactive monomer (a), and a vinyl monomer (c) copolymerizable with a copolymer of (a) and (b). For 100 parts of a composition composed of 1.0-20 parts of a reactive copolymer prepared by appropriate copolymerization,

C) 0.05-20 parts of modified silicone,

D) up to 10 parts of a lubricant is added.

The polyacetal resin (A) which can be used in the present invention is composed of substantially oxymethylene units prepared from cyclic oligomers, such as formaldehyde monomers or trimers (trioxanes) or tetramers (tetraoxanes), as raw materials. Cyclic esters such as oxymethylene homopolymer and the above raw materials and ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1,3-dioxane, glycol formal, and diglycol formal Oxymethylene and the like, and polyacetals modified by crosslinking or graft copolymerization by a known method.

(A) in the component (B) is a compound having a reactive group, for example, a reactive monomer of an epoxy-containing compound type such as glycidyl acrylate, glycidyl methacrylate and the like, and an reactive monomer of an anhydrous group such as maleic anhydride. Can be.

(B) is a copolymer monomer such as ethylene, propylene, vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate and the like.

(C) may be graft polymerized by adding a terpolymer monomer to the configured reactive copolymer (A)-(B), or may be applied by preparing a block copolymer during copolymerization. . Examples are vinyl acetate, butyl acetate, acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate, styrene, styrene-acrylonitrile compounds and the like.

As the copolymer of (A) and (B) in the reactive copolymer (B), ethylene-glycidyl acrylate, ethylene-glycidyl methacrylate, ethylene-propylene-glycidyl methacrylate, and ethylene-ethyl Block or graft copolymers such as acrylate-glycidyl methacrylate and ethylene-maleic anhydride, propylene-maleic anhydride, and ethylene-ethyl acrylate-maleic anhydride, and the like (a) and (c) Examples of the copolymer include blocks or copolymers of glycidyl methacrylate-styrene, glycidyl methacrylate-ethyl acrylate, glycidyl methacrylate-methyl methacrylate, and the like. Copolymers of (B) and (C) include ethylene-glycidyl methacrylate-styrene, ethylene-glycidyl methacrylate-vinyl acetate, ethylene-glycidyl methacrylate-methacrylic acid and ethylene- Ethylacrylate-gly Cyl methacrylate-methyl methacrylate, ethylene-ethyl acrylate-maleic anhydride-styrene, ethylene-ethyl acrylate-maleic anhydride-methyl methacrylate, ethylene-maleic anhydride-vinyl acetate and the like.

Most preferably among the above-mentioned components (B), ethylene-glycidyl methacrylate (hereinafter referred to as E / GMA) and ethylene-glycidyl methacrylate-styrene (hereinafter referred to as E / GMA / St) , Ethylene-glycidyl methacrylate-vinyl acetate (hereinafter referred to as E / GMA / VA), ethylene-glycidyl methacrylate-methylmethacrylate (hereinafter referred to as E / GMA / MA), ethylene-glycol Cydylmethacrylate-methylmethacrylate (hereinafter referred to as E / GMA / MMA), or ethylene-ethylacrylate-maleic anhydride (hereinafter referred to as E / EA / MAH), ethylene-ethylacrylate-maleic anhydride- Styrene (hereinafter referred to as E / EA / MAH / St), ethylene-ethylacrylate-maleic anhydride-styrene / acrylonitrile (hereinafter referred to as E / EA / MAH / SAN) and the like.

The copolymer (B) is produced by directly copolymerizing (A), (B) and (C) or by grafting a monomer of the (poly) component to the copolymer of (A) and (B).

In (B), the appropriate weight ratio of (A) and (B) or (A) and (C) is 5:95 to 15:95, and the appropriate weights of (A), (B) and (C) The weight ratio is 2:68:30 to 10:40:50. The suitable amount of (B) component is 1.0-20 parts with respect to (A) 99-80 parts. When used in excess of 20 parts, acetal phase separation occurs, and when used in less than 1.0 part by weight, the effect of improving wear resistance is weak.

Component (C) is a modified silicone oil having an organic group attached to one or both ends or side chains. Examples of the organic group to be attached include a hydroxy group (silanol), a chlorine group, a hydrogen group, a vinyl group, a carbinol group, an amine group, an epoxy group, a carboxyl group, a mercaptan group, and the like, and a hydroxy group (silanol) is preferable. ), An amine group, a carboxyl group, and a carbinol group.

The organic group affects abrasion resistance along with the reactivity, and the steric hindrance of the structure of the organic group when the molecular chains slide each other adversely affects the wear resistance of the substrate. Therefore, the use of organo modified siloxane which has organic group in both terminal rather than a side chain is preferable.

If the viscosity of the component (C) is too high, the diffusion rate in the molten resin is reduced, and the reaction probability of the component (B) is reduced. Therefore, the component (C) used in the present invention should have a suitable viscosity, the preferred viscosity is 100 to 10,000 centistokes (hereinafter referred to as cST), more preferably 500 to 5,000 cST. Appropriate usage-amount of (C) component is 0.05-20 parts with respect to 100 parts of sum of (A) and (B). When used in less than 0.05 parts is not sufficient to improve the wear resistance of the substrate, when used in excess of 20 parts phase separation with the substrate occurs and the problem of lowering the physical properties occurs.

In addition, the usage-amount of (C) component should be determined in consideration of the number-of-moles of the reactive functional group in (B) component, The preferable molar ratio of the mole number of the reactive functional group in (B) component and (C) component is 1: 1-1. : About 4 If the molar ratio of the component (C) is less than this range, the anti-reciprocal crosslinking structure is not properly achieved, and if it exceeds this range, the risk of outflow of unreacted silicon increases.

The modified silicone oil used in the present invention can be represented by the following general formula (1).

General formula (1)

(Wherein n is an integer of 5-200, and R represents a reactive organic which is a hydroxy group (silanol), a carbinol group, an amine group, an epoxy group, a hydrogen group, a chlorine group, a vinyl group, a carboxyl group, or a mercaptan group). )

The lubricant as the component (D) is added to impart more improved friction wear characteristics. One or two or more kinds of conventional lubricants such as solid lubricants, mineral oils, metal soaps and fatty acid esters can be used in combination.

The composition of the present invention may be appropriately added to the above-mentioned various additives known as heat stabilizers, light stabilizers, antistatic agents, colorants, fillers and the like depending on the purpose of use.

Embodiments of the present invention are as follows.

Example 1-10)

95 parts of polyacetal resin copolymer (Korea Engineering Plastics Co., Ltd. make, brand name KEPITAL F20-03 (MI: 9.0g / 10min)) as A) component,

B) Poly (E / GMA) containing 5 to 10 moles of epoxy component as the component, or Poly (E / GMA / VA), Poly (E / GMA / MA) containing 2 to 10 moles of epoxy component, 10 to 5 parts of Poly (E / GMA / St), Poly (E / GMA-SAN).

C) As a silicone oil having an organic modification group on the molecular sock end of polydimethylsiloxane as a component, silicone oil having a hydroxyl group (Dongyang Silicon YF-3057), silicone oil having an amine group (Shinwol Chemical Co., Ltd., KF 861, KF 864) , X-22-161C) and a silicone oil having a carboxyl group (Dongyang Silicone, TSF 4770) were added to support a 1: 1 molar ratio of the epoxy groups in the B) component.

As the D) component, polydimethylsiloxane, fatty acid ester and mineral oil were added as shown in Table 1).

In the processing method, B) component and C) component were kneaded well in a Hensian mixer first, and then reacted in a single screw extruder, and the reactant was pelletized. Secondly, the reactant pellet and A) component (KEPITAL F20-03) After tumbling) was mixed with various known heat stabilizers and antioxidant processing aids to prepare a sample through a single screw extruder. At this time, antioxidants, processing aids, etc. were mixed together and processed, and the evaluation of physical properties is shown in Table 1).

Example 11-23)

Poly (E / GMA / VA), Poly (E / GMA / MA), Poly (E / GMA / St), Poly (E) as A) component 90-95 parts B) component used in Example 1-10 / GMA / MMA) was added from 10 to 5 parts, and the C) component was added at a reaction molar ratio of 1: 2 to 1: 4.

As the component D), various fatty acid esters were added as shown in Table 2). Processing method was processed in the same manner as in Example 1-10, the physical properties and results are shown in Table 2).

Example 24-34)

Poly (E / VA / MAH), Poly (E / MHA / St), Poly (E / EA / MAH-MMA), Poly as A) component 90-95 parts B) components used in Example 1-10 10-5 parts of (E / EA / MAH-SAN) was added thereto, and the C) component was added at a reaction molar ratio of 1: 1 to 1: 4. The processing method was the same as in Example 1-10, and the results of evaluation of the physical properties are shown in Table 3).

Comparative Example 1-17)

A) Component 100-90 parts of polyacetal, B) Poly (E / GMA), Poly (E / EA / MAH / MMA), Poly (E / GMA / St), Poly (E / GMA-MA ), 10 to 5 parts of ethylene vinyl acetate copolymer (EVA) and low density polyethylene (LDPE) are added, and D) components, which are various lubricants, are not added to the C) component, which is a reactive silicone. Injected in the same composition as 4 to evaluate the physical properties.

The physical property evaluation method of the composition obtained by each said Example and the comparative example is as follows.

1) Moldability Evaluation

Evaluate the weighability during injection molding of manufactured pellets

Short ----- Measurement Time ----- Long

⊙ ○ ○ △ △ × × ×

2) peeling molded products

A disk test piece of 2 mm in thickness and 100 mm in diameter was molded under severe injection conditions (injection rate of 50 cc / sec, injection pressure of 1000 kg). At this time, the surface peeling phenomenon observed in the molded part and sprue was observed.

None ----- Peeling degree--Many

⊙ ○ ○ △ △ × × ×

3) oil spill

The original test piece was heat-treated at 150 ° C. for 73 hours in a vacuum dry oven under vacuum to observe the degree of oil leakage from the surface of the test piece under an optical microscope.

In addition, the pellets were impregnated with carbon tetrachloride and stirred for 72 hours with a shaker to evaluate the degree of additives flowing out at this time.

Low ----- Outflow degree ----- Large

⊙ ○ ○ △ △ × × ×

4) Mold Deposit Measurement

After injection of 1000 shots at a cylinder temperature of 220 ° C. using a mold deposit knot in an injection molding machine, the degree of adherence attached to the mold was observed through a projector.

Low ----- Outflow degree ----- Large

⊙ ○ ○ △ △ × × ×

5) Evaluation of Friction Wear

Evaluation of dynamic friction coefficient and wear rate using thrust friction wear tester

① Dynamic friction coefficient: counterpart-metal (S45C steel) # 1200 polishing, Ra: 0.3㎛ or less

Linear velocity: 30cm / sec, Load: 11.6㎏f

② Abrasion Amount: Counterpart-Resin

Linear velocity: 10cm / sec, Load: 6.6㎏f

Claims (5)

In the polyacetal resin composition composed of a polyacetal resin, a reactive group-containing copolymer, a lubricant, (A) 99-80 parts by weight of a polyacetal resin, (B) a compound having a reactive group (a), a monomer copolymerizable with a reactive monomer (a) (b), and (a) and (b) (C) modified silicone represented by the following general formula (I) based on 100 parts by weight of a composition composed of 1.0-20 parts by weight of a reactive copolymer prepared by appropriately copolymerizing a vinyl monomer (C) copolymerizable with the copolymer. 20 parts by weight and D) less than 10 parts by weight of a lubricant are added, wherein the molar ratio of the number of moles of the reactive functional group in the component (B) and the component (C) is 1: 1 to 1: 4. . General formula (1) (Wherein n is an integer of 5-200, and R represents a reactive organic group which is a hydroxy group (silanol), a carbinol group, an amine group, an epoxy group, a hydrogen group, a chlorine group, a vinyl group, a carboxyl group, or a mercaptan group). ) The polyacetal resin composition according to claim 1, wherein the reactive compound (A) in component (B) is one selected from an epoxy-containing compound and an anhydride-based compound. The method of claim 1, wherein (b) in component (B) is a copolymer monomer such as ethylene, propylene, vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate and the like. Polyacetal resin composition characterized in that. (C) in component (B) is vinyl acetate, butyl acetate, acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate, styrene, styrene-acrylic. Polyacetal resin composition, characterized in that the at least one monomer selected from the ronitrile compound. The composition according to claim 1, wherein component (B) is ethylene-glycidyl methacrylate alone or a composition in which vinyl acetate, methyl acrylate, methyl methacrylate, styrene is copolymerized thereto, or ethylene-ethyl acrylate-anhydrous A polyacetal resin composition characterized in that maleic acid alone or a styrene or styrene-acrylonitrile polymer is copolymerized thereto.