KR950006139B1 - Low Gloss Polyacetal Resin Compositions and Molded Articles - Google Patents

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Description

Low Gloss Polyacetal Resin Compositions and Molded Articles

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal resin composition in which surface gloss is suppressed and exhibits excellent weather resistance (photo) properties. In particular, the present invention relates to a polyacetal resin composition comprising a polyacetal resin, a characteristic silicone graft copolymer and, if necessary, Provided are a polyacetal resin composition and its molded article having low surface gloss and improved weatherability without compromising the inherent balanced mechanical properties.

As is known, polyacetal resins have recently been used in various fields as engineering plastics having excellent physical properties such as mechanical and electrical properties and chemical properties such as chemical resistance and heat resistance. However, as the field of use of polyacetal resins expands, there are cases where resins are required to exhibit more specific properties as their materials.

One of these properties is low gloss, i.e. low light, which is required in automotive interior parts and optics for the purpose of suppressing eye irritation caused by light reflection, preventing malfunction of the device, and showing high-quality appearance. It is reflective. In addition, in the fields of electrical equipment and building materials, opportunities for using two or more materials in combination according to the purpose are increasing. In this case, since polyacetal resin has a higher surface gloss than other common resin materials, polyacetal resin lacks compatibility with other materials when assembling parts made of various materials including polyacetal resin. Do. Therefore, in terms of surface appearance, the field of use of the polyacetal resin is quite limited. As a means for satisfying the low surface glossiness requirement, a method of adding an inorganic filler such as calcium oxide or talc to a polyacetal resin is known. However, according to this method, in order to obtain a desirable gloss reduction effect, it is necessary to mix a large amount of talc and the like, and as a result, mechanical properties, in particular elongation and stiffness, are lowered, resulting in stress during processing or assembling of the molded product or handling of the molded product. It has the drawback that it is easily broken by an impact such as falling down. Moreover, since the polyacetal resin composition prepared by the above method is poor in weather resistance, molded articles made of this resin when exposed to sunlight (ultraviolet rays) or boiling in the open air for a long period of time have a defect in surface condition (uniformity, discoloration, etc.). have. Under these circumstances, development of a polyacetal resin with excellent surface weather resistance and excellent weather resistance has been desired.

The inventors of the present invention achieve the present invention by intensive research to reduce the surface gloss of the polyacetal resin and improve the weather resistance of the polyacetal resin in outdoor use without damaging the original properties of the polyacetal resin. It was.

That is, this invention adds and mixes 0.1-40 weight part of silicone graft copolymers prepared by radical copolymerization of (B) acrylic modified silicone (a) and radically polymerizable monomer (b) to 100 weight part of (A) polyacetal resins. As a polyacetal resin composition having a low glossiness, and in addition to the above essential components, a surface acetone containing 0.01 to 5 parts by weight of (C) weathering (light) stabilizer is further lowered, and as a polyacetal resin composition showing excellent weatherability, as these compositions It is to provide a low gloss molded article.

Hereinafter, the configuration of the present invention will be described in detail.

First, the polyacetal resin (A) used in the present invention is a high molecular compound having an oxymethylene group (-CH ₂ O-) as its main structural unit, and contains a small amount of other monomers in addition to the polyoxymethylene homopolymer or oxymethylene group. It may be any of copolymers, terpolymers and block copolymers. These (co) polymers can be linear, branched, crosslinked, and their degree of polymerization is not particularly limited.

Second, the (B) silicone graft copolymer used in the present invention is a polymer compound prepared by radical copolymerization of an acrylic modified silicone (a) and a radical polymerizable monomer (b). The acrylic modified silicone (a) which comprises (B) in silicone graft copolymerization is a condensation reaction product of the silicone represented by following General formula (1), and the acrylic compound represented by General formula (2).

(Wherein R ¹ and R ² are a C1-C10 aliphatic hydrocarbon group, a phenyl group, or a halogenated hydrocarbon group, n is an integer of 2 or more)

(Wherein R ³ is a hydrogen atom or a methyl group, R ⁴ is a methyl group, an ethyl group, or a phenyl group, X is an alkoxy group having 1 to 10 carbon atoms, an acetoxy group, or a chlorine atom)

Substituents R ¹ and R ² bonded to the silicon atom of silicon represented by the general formula (1) are an aliphatic hydrocarbon group, a phenyl group or a halogenated hydrocarbon group having 1 to 10 carbon atoms, preferably a methyl group.

As an acryl compound represented by the said General formula (2), (gamma) -methacryloxypropyl dimethyl chlorosilane, (gamma) -methacryloxypropyl diethoxysilane, (gamma) -methacryloxypropyl diethyl chlorosilane, (gamma) -acryloxypropyl dimethyl chloro Silane, γ-methacryloxypropyltrichlorosilane, γ-methacryloxypropyltriethoxysilane, and the like.

Preferred examples of acryl-modified silicone (a) include condensates of α, ω-dihydroxypolydimethylsiloxane and γ-methacryloxypropyldimethylchlorosilane or condensates of γ-methacryloxypropyltrichlorosilane.

Next, as the radically polymerizable monomer (b) constituting the silicone graft copolymer (B), methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic Vinyl esters of organic acids such as acid cyclohexyl, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, styrene and vinyl acetate, and low molecular weight such as ethylene and propylene, and straight chain hydrocarbons.

Of the above monomers, preferably acrylic acid or methacrylic acid or esters thereof, more preferably acrylic acid, methyl acrylate, methacrylic acid or methyl methacrylate are used.

Among the silicone graft copolymers prepared from the above-described components, (a) condensates of α, ω-dihydroxypolymethylsiloxane and γ-methacryloxypropyldimethylchlorosilane (b) methyl acrylate or methacrylic acid Particular preference is given to using those prepared by radical copolymerization of methyl.

The silicone graft copolymer (B) used in the present invention is not used independently of the acrylic modified silicone polymer (a) and the radical polymerizable monomer or polymer (b) constituting the main chain portion of the copolymer (B). Both are characterized by their use as graft copolymers. As will be described later, while these graft structures allow significant effects to be obtained in the present invention, they cannot be obtained by the addition of component (a) or (b) alone.

The method for producing the graft copolymer is not particularly limited, but for example, the acrylic modified silicone (a) constituting the silicone graft copolymer (B) can be produced very easily by conventional condensation reaction. That is, when X of the acryl compound represented by General formula (2) is a chlorine atom, condensation can also be performed by hydrogen halide removal reaction in presence of an acid acceptor. On the other hand, when X is a methoxy or ethoxy group, condensation may be carried out by the removal reaction of alcohol molecules. In the condensation reaction, the compound represented by the general formula (2) and the silicon represented by the general formula (1) can be used having an equivalent ratio of Si-X group SiOH groups as 0.25 to 1. If the amount of the compound (2) is too large, the obtained silicone graft copolymer (B) is easily gelled, whereas if the equivalent ratio is less than 0.25, a large amount of unreacted silicon remains, which is not preferable.

The acrylic modified silicone (a) prepared by the above method can be extremely smoothly copolymerized with a normal radically polymerizable monomer to obtain a silicone graft copolymer (B). The amounts of components (a) and (b) constituting the silicone graft copolymer (B) are suitably selected such that the silicon content in the silicone graft copolymer is 5 to 80% by weight, preferably 10 to 70% by weight. .

Although the molecular weight of the graft copolymer thus prepared is not particularly limited, it is generally 1000 to 200000, preferably 5000 to 150000.

According to this invention, the quantity of component (B) used is 0.1-40 weight part per 100 weight part of component (A), Preferably it is 5-20 weight part. The amount of component (B) is too small, the surface gloss reduction effect is not sufficiently obtained, while if the amount is too large, mechanical properties or thermal stability are adversely affected and economic disadvantages are generated.

Molded articles manufactured from the composition consisting of polyacetal resin (A) and silicone graft copolymer (B) have a uniform surface gloss, which provides a stable and high-quality appearance, and is sufficiently improved in terms of weather resistance. . The reason why the surface gloss is lowered is that the part of the silicone graft copolymer (B) dispersed in the molded article in the form of particles having a size of 0.5 to 2 μm reaches the surface of the molded article to roughen the surface, thereby decreasing the surface gloss and making the surface uniform It is thought that a part of the silicon dispersed in this way covered the polyacetal resin to further reduce the surface gloss. Although the surface gloss varies depending on the molding conditions and the mold surface finish, the practically preferable surface gloss is 40% or less, more preferably 15% or less, as measured by the manufacturing method described below.

The composition of the present invention exhibits low gloss and excellent weather resistance even when used as it is, but when used with the addition of a weathering stabilizer (C), the weathering resistance can be improved, especially in the prevention of cracking and discoloration of the surface of a molded article. Better effect.

Weathering (light) stabilizers preferably used in the present invention include (1) benzotriazole, (2) benzophenone, (3) oxanilide, (4) aromatic benzoate, (5) cyanoacrylate and (6) At least one selected from the group consisting of hindered amines.

Examples of this stabilizer are as follows.

That is, examples of benzotriazole (1) include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl ) Benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- [2'-hydroxy-3 ', 5'-diasoamylphenyl) benzotria Sol, 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole and 2- (2'-hydroxy-4'-octoxyphenyl) benzotria There is a slumber.

Examples of benzophenone (2) include 2,4-dihydroxybenzophenone, 2-hydroxy-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-octoxybenzophenone and 2-hydroxy 4-dodecyloxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone and 2-hydroxy-4 -Oxybenzylbenzophenone, and the like.

Examples of oxanilide (3) include N- (2-ethylphenyl) -N '-(2-ethoxy-5-t-butylphenyl) oxanilide and N- (2-ethylphenyl) -N'-(2 Ethoxyphenyl) oxananilide, and the like.

Examples of the aromatic benzoate (4) include P-t-butylphenyl salicylate and P-octylphenyl salicylate.

Examples of cyanoacrylate (5) include 2-ethylhexyl-2-cyano-3, 3-diphenylacrylate and ethyl-2-cyano-3, 3-diphenylacrylate and the like.

The hindered amine (6) is a piperidine derivative having a steric hindrance group, and examples thereof include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2, 6,6-tetramethylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6 , 6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine , Bis (2,2,6,6-tetramethyl-4-piperidyl) oxalate, bis (2,2,6,6-tetramethyl-4-piperidyl) malonate, bis (2,2 , 6,6-tetramethyl-4-piperidyl) adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6 -Peptamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) terephthalate, 1,2- S (2,2,6,6-tetramethyl-4-piperidyloxy) ethane, bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarba Mate, bis (1-methyl-2,2,6,6-tetramethyl-4-piperidyl) adipate and tris (2,2,6,6-tetramethyl-4-piperidyl) benzyl-1 , 3,5-tricarboxylate and the like. Furthermore, high molecular weight piperidine derivative polycondensates such as condensates among dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethyl-piperidine are effectively used. do.

According to the present invention, the weathering (light) stabilizer may be used one kind or two or more kinds. In particular, it is effective to use one of the stabilizers (1) to (5) in combination with hindered amine (6), and more particularly, to use benzotriazole (1) and hindered amine (6) in combination. to be.

The weathering (light) stabilizer (C) may be used in an amount of 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, per 100 parts by weight of component (A). If the amount of this stabilizer (C) is too small, no effect can be obtained, while if the amount is too large, not only economic disadvantages but also deterioration of mechanical properties or contamination of the mold can be caused. Although the composition prepared by adding the weathering (light) stabilizer (c) alone to the polyacetal resin exhibits some excellent weathering resistance, the weathering resistance is not sufficiently satisfactory when exposed to sunlight (ultraviolet) or rain for a long time outdoors. When the weathering (light) stabilizer is used together with the silicone graft copolymer (B), molded articles exhibiting low surface glossiness and improved weatherability can be obtained. Moreover, it is preferable that the composition of the present invention further includes various known stabilizers in order to improve thermal stability and the like. For this purpose, it is preferable to use one or two or more selected from known antioxidants, nitrogen compounds and alkali and alkaline earth metal compounds.

In addition, the composition of the present invention may be optionally colored by adding various carbon blacks or other dyes and pigments.

In particular, the use of carbon black is effective in further improving the weather resistance of the composition.

The composition of the present invention may contain one kind or two or more kinds of common additives in order to impart desired properties in accordance with the purpose. Examples thereof include lubricants, nucleating agents, mold releasing agents, antistatic agents, other surfactants, components (B) and other organic polymer materials, inorganic or organic fibrous, granular, powdery or plate-like fillers.

The combination of well-known participant (for example, talc, calcium carbonate, aluminum silicate) which has a gloss fall effect is somewhat effective.

In general, the composition of the present invention may be prepared by known equipment and methods as a method of preparing a synthetic resin composition. That is, the necessary components are mixed together, kneaded and extruded using a uniaxial or biaxial compressor to form a fillet. Alternatively, the production of the composition may be performed simultaneously with molding in a molding machine. Furthermore, a method may be used in which a part or all of the resin component is pulverized, the pulverized component is mixed with the remaining components, and then the melt-extruded pellets are molded.

The stabilizers and additives may be added at any stage and may be added just prior to manufacture of the final molded article.

The resin composition of the present invention can be molded by compression molding, injection molding, compression molding, vacuum molding, blow molding or foam molding.

As described above, the composition of the present invention consisting of a polyacetal resin and a specific silicone graft copolymer exhibits the effect of obtaining a molded article in which the surface gloss is significantly lowered without impairing the original balanced mechanical properties of the polyacetal resin.

Furthermore, compositions comprising weathering (light) stabilizers in addition to the above components further improve the weatherability which is a problem when inorganic fillers (active or calcium carbonate) are used. In particular, the crack initiation time is significantly shortened and discoloration is reduced.

Accordingly, the low gloss polyacetal resin composition of the present invention is a molded article requiring high-quality appearance and high weather resistance (light), that is, automobile interior parts (eg, inner handle, adjustment handle, interior creep, etc.) And exterior parts (e.g. outer handles, fuel lids, etc.), electric devices, building materials, cameras, household goods, etc. for long-term exposure to sunlight and boiling atmospheres to have a stable surface appearance It can be used suitably.

EXAMPLE

Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

In the examples, specific values such as surface appearance and weather resistance were measured by the following method.

(1) surface appearance

The surface appearance was divided into 1 to 4 grades, and the uniformity of the surface of the matte state was evaluated. Here, the smaller the number, the better the glossiness state and the uniformity state.

When the sample was irradiated with a fluorescent lamp, the contour of the fluorescent lamp was not seen on the surface of the sample and the surface was uniformly roughened.

The contour of the fluorescent lamp was not seen on the surface, but the surface of the sample was unevenly roughened.

3 ... The outline of a fluorescent lamp is seen on the surface of a sample, but it is unclear.

The contour of the fluorescent lamp is clearly seen on the surface, and the surface is almost flat.

(2) surface glossiness

Glossiness at 45 ° -45 ° reflection as a digital variable gloss system (UGV-40 manufactured by Water Test Instruments Corp.) by the method of JISK 7105 using a test piece (70 mm x 40 mm x 3 mm) manufactured by molding under the following conditions. Was measured.

○ Molding machine: IS80 manufactured by Toshiba Corporation

○ Molding condition:

Nozzle C ₁ C ₂ C ₃

Cylinder temperature 200 190 180 160 (℃)

Injection pressure 650 (kg / cm ² )

Injection speed 1.0 (m / min)

Mold temperature 80 (℃)

(3) weather resistance test

Using a climatic system (water tester WBL-SUN-HCH type), ultraviolet rays were irradiated under a black panel temperature of 63 ° C. and a climate (including rainfall spray) to measure the uniform occurrence time and surface appearance change. .

① Crack occurrence time

Ultraviolet rays were irradiated to the test piece under the above conditions, and the surface of the test piece was observed with a 10 × magnifier, and the time elapsed until the first crack was observed. This time was regarded as the crack initiation time. Larger values indicate better weather resistance.

② Change in surface appearance

The test piece was irradiated with ultraviolet rays for a predetermined time (600, 1000 or 200 hours) under the above conditions, and the color change and the crack change of the test piece were observed before and after the irradiation, and the change was expressed in 5 grades. Smaller numbers mean less change, ie less discoloration and cracking.

(4) tensile test

Tensile strength and tensile elongation were measured according to ASTM D 638.

[Examples 1 to 19 and Comparative Examples 1 to 17]

As shown in Table 1, polyacetal resin (A) (polyplastics product: trade name "Duracon (M90)") was used as the silicone graft copolymer (B) alone or as a weathering (light) stabilizer (C) and, if necessary, The mixture obtained by mixing with carbon black was melt kneaded with a 30-mm twin screw extruder to prepare a pellet-like composition. The composition was molded into test pieces using an injection molding machine to measure and evaluate gloss, weather resistance and other properties. For comparison, as shown in Table 2, in addition to the component (B), the grafted silicone oil, an acrylic resin, a weathering stabilizer, and / or a known additive having a gloss lowering effect were used. The same method was repeated.

The results are shown in Table 1 and Table 2.

TABLE 1

TABLE 2

Note-1)

B-1: Copolymer of acrylic modified silicone and methyl methacrylate prepared from α, ω-dihydroxy polydimethylsiloxane and γ-methacryloxypropyldimethylchlorosilane

B-2: Copolymer of acrylic modified silicone and methyl methacrylate prepared from α, ω-dihydroxy polydimethylsiloxane and γ-methacryloxypropyltrichlorosilane

Note-2)

C-1: 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) -phenyl] benzotriazole

C-2: 2-hydroxy-4-oxybenzylbenzophenone

C-3: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate

C-4: Dimethyl succinate- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate

Claims (8)

A low gloss polyacetal resin composition comprising (A) 100 parts by weight of a polyacetal resin, and (B) 0.1 to 40 parts by weight of a silicone graft copolymer prepared by radical copolymerization of acrylic-modified silicone (a) and a radical polymerizable monomer. The low gloss poly according to claim 1, wherein the acrylic modified silicone (a) constituting the component (B) is a condensation reaction product of a silicone represented by the following general formula (1) with an acrylic compound represented by the general formula (2): Acetal resin composition. (Wherein R ¹ and R ² are a C1-C10 aliphatic hydrocarbon group, a phenyl group, or a halogenated hydrocarbon group, n is an integer of 2 or more) (Wherein R ³ is a hydrogen atom or a methyl group, R ⁴ is a methyl group, an ethyl group, or a phenyl group, X is an alkoxy group having 1 to 10 carbon atoms, an acetoxy group, or a chlorine atom) The acryl-modified silicone (a) constituting component (B) according to claim 1 or 2, wherein?,?-Dihydroxypolydimethylsiloxane and? -Methacryloxypropyldichlorosilane or? -Methacryloxypropyl A low gloss polyacetal resin composition which is a condensation reaction product with trichlorosilane. The low gloss polyacetal resin composition according to claim 1 or 2, wherein the radical polymerizable monomer (b) constituting the component (B) is acrylic acid, methacrylic acid or an ester thereof. The low gloss polyacetal resin composition according to claim 1, which further contains 0.01 to 5 parts by weight of a weather (light) stabilizer (c) per 100 parts by weight of polyacetal. The low gloss according to claim 5, wherein the weathering stabilizer (c) is one or two or more selected from the group consisting of benzotriazole, benzophenone, oxanilide, aromatic benzoate, cyanoacrylate and hindered amine. Polyacetal resin composition. The use of one or two or more hindered amines according to claim 6, wherein the weathering stabilizer (c) is selected from benzotriazole, benzophenone, oxinylide, aromatic benzoate and cyanoacrylate. Low gloss polyacetal resin composition consisting of. A low gloss polyacetal resin molded article produced by molding the composition of claim 1.