JPH07119351B2 - Weather resistant polyacetal resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a polyacetal resin composition having excellent weather (light) resistance. More specifically, a weather resistant (light) stabilizer, an acrylic resin, and a specific oxyalkylene polymer are added to a polyacetal resin to provide a polyacetal resin composition having excellent weather resistance and a molded article thereof. .

[Conventional technology and its problems]

As is well known, polyacetal resins have recently been used in an extremely wide range of fields as engineering resins having excellent physical properties such as mechanical properties and electrical properties, or chemical properties such as chemical resistance and heat resistance. However, with the expansion of fields in which polyacetal resins are used, the properties of the materials may be required to be more specific. As one of such peculiarities, further improvement in weather (light) resistance is demanded. That is, interior and exterior parts such as automobiles and parts such as electric equipment are exposed to sunlight,
Depending on the atmosphere used, such as fluorescent lighting, rain, or other atmospheric contact, the color may change or the surface may lose its smoothness to lose its luster, and further cracks may occur on the surface of the component to impair the appearance. In order to prevent these drawbacks, it has been conventionally proposed to add various weather resistance (light) stabilizers to the polyacetal resin to improve the weather resistance (light) of the polyacetal resin.

However, the methods using these stabilizers are not always satisfactory, and more excellent weather (light) stability is required.

By adding and blending a weather resistance (light) stabilizer and an acrylic resin to the polyacetal resin, although a temporary effect for improving the weather resistance (light) resistance is recognized, sunlight (ultraviolet rays), especially outdoors for a long time, When exposed to rain, etc., the surface condition (cracks, gloss, etc.) of molded products, mechanical properties, etc. are not necessarily satisfactory, and even more excellent weather resistance (light) stability is required. There are many.

In addition, there is a limit to the improvement of weather resistance (light) even if the amount of weather resistance (light) stabilizer, acrylic resin, etc. is simply increased.
In addition, the increase of these additives and the like causes deterioration of mechanical properties (especially tensile elongation, Izod impact strength, etc.), while
During molding, mold release defects, dimensional defects due to adhesion and deposition on the mold (so-called mold deposit), appearance defects of molded products, etc., increase in the number of mold cleaning operations Various defects such as worsening,
I have a problem.

[Means for Solving the Problems]

The present inventors have conducted intensive studies to further improve the weather resistance (light) stability of the polyacetal resin in outdoor use without sacrificing the original properties of the polyacetal resin, and completed the present invention. .

That is, the present invention relates to (A) a polyacetal resin, (B) 0.01 to 5% by weight of a weathering (light) stabilizer (based on the total composition).
And (C) 1 to 40% by weight of acrylic resin (relative to the total composition) and (D) 0.1 to 10% by weight of oxyalkylene polymer having 2 to 8 adjacent carbon chains (relative to the total composition). The present invention relates to a weather resistant polyacetal resin composition.

The (A) polyacetal resin used in the present invention is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main constituent unit, and contains a small amount of other constituent units in addition to the polyoxymethylene homopolymer and the oxymethylene group. The copolymer may be a terpolymer or a block copolymer, and the molecule may have not only a linear structure but also a branched or crosslinked structure. Further, there is no particular limitation on the degree of polymerization or the like.

Next, among the (B) weathering (light) stabilizers used in the present invention, preferably used are benzotriazole-based substances, benzophenone-based substances, aromatic benzoate-based substances, cyanoacrylate-based substances, oxalic acid anilide-based substances, and One or more selected from the group consisting of hindered amine-based substances.

Examples of these substances include the following.

That is, as the benzotriazole-based substance, 2-
(2'-hydroxy-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl-phenyl) benzotriazole, 2-
(3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-isoamyl-phenyl) benzotriazole, 2
-[2-Hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2 '
-Hydroxy-4'-octoxyphenyl) benzotriazole and the like, benzophenone-based substances include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy- 4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy- Aromatic benzoate-based substances such as 4-oxybenzylbenzophenone, pt-butylphenyl salicylate, p-octylphenyl salicylate and the like, and cyanoacrylate-based substances such as 2-ethylhexyl-2-cyano-3,3'- Diphenyl ac Rate, ethyl 2-cyano-3,3'-diphenyl acrylate, etc. Examples of the oxalic acid anilide-based substance, N-(2-ethyl--
Phenyl) -N '-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N- (2-ethyl-phenyl)
-N '-(2-ethoxy-phenyl) oxalic acid diamide and the like.

The hindered amine-based substance is a piperidine derivative having a sterically hindering group, and examples thereof include 4-acetoxy-2,2,6,6-tetramethylpiperidine and 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- (phenylcarbamoyoxy) -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-pentamethyl-piperidyl) sebacate, bis (2,2,6,6-
Tetramethyl-4-piperidyl) terephthalate, 1,2
-Bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane, bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, bis ( 1-methyl-2,2,6,6-tetramethyl-4-piperidyl) adipate, tris (2,2,6,6-tetramethyl-4)
-Piperidyl) benzene-1,3,5-tricarboxylate and the like. Further, a high molecular weight piperidine derivative polycondensate such as dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate of succinate is also effective.

These weather resistance (light) stabilizers are at least one kind or two kinds.
It is preferable to mix one or more kinds, and it is particularly preferable to use the above-mentioned weather resistance stabilizer and a hindered amine-based substance in combination.

The weather resistance (light) stabilizer (B) used here is preferably 0.01 to 5% by weight (relative to the total composition), and particularly 0.02 to 3% by weight.
Is preferred. If these components are too small, no effect can be expected, and even if they are added unnecessarily excessively, not only the economical disadvantage but also the problems such as the deterioration of mechanical properties and the contamination of the mold are brought about. .

Next, the acrylic resin (C) used in the present invention means acrylic acid, acrylic acid ester (for example, methyl acrylate, ethyl acrylate, acrylate n-propyl, isopropyl acrylate, acrylate n-butyl). , Acrylic acid-n-hexyl, acrylic acid-n-octyl, etc.), methacrylic acid and methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, methacrylate-n-propyl methacrylate, isopropyl methacrylate,
-N-butyl methacrylate, isobutyl methacrylate,
Homopolymers or copolymers such as methacrylic acid-n-amyl, methacrylic acid-n-octyl, etc.) or copolymers of these components with styrene, acrylonitrile, butadiene, isoprene and the like. Among these, a methyl methacrylate homopolymer or a copolymer containing methyl methacrylate as a main component and containing an acrylic acid ester or a methacrylic acid ester (other than methyl methacrylate), styrene, acrylonitrile and the like is preferably used.

The addition amount of the acrylic resin (C) used here is 1 to
40% by weight (relative to the total composition) is suitable, especially 5 to 30% by weight. If the addition amount is too small, the weather resistance (light) resistance will not be sufficient, especially if cracks on the surface of the molded product are prevented, and even if added unnecessarily, it will have an unfavorable effect on mechanical properties and thermal stability. Cause

When such an acrylic resin (C) is used in combination with the weather resistance (light) stabilizer (B), the weather resistance (light) resistance is improved but is still insufficient, and the mechanical properties are deteriorated as described above. However, there are problems such as deterioration of molding work.

Therefore, the composition of the present invention is characterized in that the component (A), (B), (C) is further mixed with (D) an oxyalkylene polymer having 2 to 8 adjacent carbon chains.
By blending the four components of (A), (B), (C), and (D), the weather resistance (light) (especially glossiness) is maintained without impairing the balanced properties inherent to the polyacetal resin. It has been found that it is extremely effective in improving retention, generation of cracks, etc.).

In the present invention, the carbon chain used for such purpose is 2 to
Examples of 8 adjacent oxyalkylene polymers include poly (ethylene oxide), poly (propylene oxide), poly (butylene-1,2-oxide), polyoxolane, polyoxane, polyoxepane, polyoxocane and polyoxonan, and ethylene oxide / propylene oxide copolymers. Examples thereof include polymers and ethylene oxide / oxolane copolymers. Here, the copolymer means a random copolymer, a block copolymer, a graft copolymer and a mixture thereof. The molecular weight (number average) of the oxyalkylene polymer used is 50.
It is 0 to 200,000, preferably 4,000 to 50,000. Among these, oxyalkylene polymers having 2 to 4 carbon chains adjacent to each other are preferable, and poly (oxyethylene), poly (propylene oxide), poly (butylene-1,2-oxide), polyoxolane and ethylene oxide / propylene oxide copolymers are preferable. Examples thereof include polymers. More preferred are poly (ethylene oxide), poly (propylene oxide), and ethylene oxide / propylene oxide copolymer.

The amount of the oxyalkylene polymer (D) used here is appropriately 0.1 to 10% by weight (based on the total composition), and particularly preferably 2 to 6% by weight. If the amount is less than 0.1% by weight, the effect of improving the weather resistance is small, and if the amount is more than 10% by weight, the effect of the improvement reaches saturation and the original properties of the polyacetal resin are adversely affected.

Such an oxyalkylene polymer (D) does not improve the weather resistance so much even if it is used alone or in combination with the weather resistance (light) stabilizer (B) or the acrylic resin (C) in the polyacetal resin, but the three components (B + C + D). When used together, a remarkable synergistic effect is exerted, the occurrence of cracks on the surface of the molded product is suppressed, and at the same time the gloss of the molded product is maintained for a long time and the discoloration degree is extremely small. .

Such an effect is that the oxyalkylene polymer has a compatibilizing effect on both the polyacetal resin (A) and the acrylic resin (C), improves the fluidity of the acrylic resin (C), and easily collects on the surface of the molded product. It is presumed that this is due to Therefore, the weather resistance is remarkably improved and the tensile elongation and Izod impact strength are improved with a small addition amount of the acrylic resin.

The composition of the present invention is preferably further added with various known stabilizers to reinforce thermal stability and the like, and for this purpose, known antioxidants, nitrogen-containing compounds, alkali or alkaline earth metal compounds and the like are added. It is desirable to use one kind or a combination of two or more kinds.

Further, the composition of the present invention can be colored in any color by appropriately adding various carbon blacks and other various dyes and pigments.

In particular, the combined use with carbon black has the effect of further improving the weather resistance (light) stability.

In order to impart desired properties to the composition of the present invention depending on its purpose, conventionally known additives such as lubricants, nucleating agents, release agents, antistatic agents and other surfactants, or organic polymer materials, It is also possible to add one or more kinds of inorganic or organic fibrous, powdery or plate-like fillers.

The composition of the present invention can be prepared by the equipment and method generally known as a method for preparing a synthetic resin composition. That is, the necessary components can be mixed, kneaded using a uniaxial or biaxial extruder, extruded into pellets for molding, and then molded, and the composition can be molded by a molding machine. It is also possible to do it at the same time. Further, in order to improve dispersion and mixing of the respective components, a method of pulverizing a part or all of the resin components, mixing and molding the pellets melt-extruded, or the like is possible.

In addition, the compounds such as the stabilizers and additives may be added at any arbitrary stage, and it is of course possible to add and mix them immediately before obtaining the final molded product.

Further, the resin composition according to the present invention can be molded by any of extrusion molding, injection molding, compression molding, vacuum molding, blow molding, and foam molding.

〔Example〕

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The methods used for evaluating the characteristic values such as weather resistance (light) in the examples are as follows.

1) Weather resistance test (A, B) The following two types of weather resistance testers were used to evaluate changes in crack generation time and surface condition.

Test A method: Super accelerated weathering tester [SUV-W- manufactured by Iwasaki Electric Co., Ltd.
11 type] and was irradiated with ultraviolet rays in an atmosphere of 83 ° C. for evaluation.

Test B method: Weather meter [SBL Tester Co., Ltd. WBL-SU
N-HCH type] 63 ℃, weather (with rain spray)
The condition was evaluated by irradiating ultraviolet rays.

Crack generation time Using the above weather resistance tester, the test piece is irradiated with ultraviolet rays for a certain period of time under a predetermined condition to check for cracks on the surface of the test piece.
It was observed with a magnifying glass of 10 times, and the time when the crack was first observed was defined as the time of occurrence of the crack. The larger the value, the better.

Gloss change Using the above weather resistance tester, the test piece was irradiated with ultraviolet rays for a certain period of time under a predetermined condition, and the change in gloss of the test piece before and after irradiation was observed, and the degree of change was classified into 5 levels. indicate. As shown in the table below, the smaller the number, the smaller the change, that is, the lower the gloss.

The gloss is a digital variable angle gloss meter (UGV-4 manufactured by Suga Test Instruments Co., Ltd.)
D), and the degree of decrease in gloss was measured by the retention ratio with the initial state.

Degree of change Gloss retention rate (%) 1 to 85 2 85 to 70 3 70 to 50 4 50 to 20 5 20 to 2) Physical property measurement method Tensile elongation conforming to ASTM D 638 Izod impact strength (with notch) ASTM D 256 Examples 1 to 16 and Comparative Examples 1 to 12, as shown in Table 1, (A) polyacetal resin [manufactured by Polyplastics Co., Ltd., trade name "Duracon (M90)"]
(B) weather resistance (light) stabilizer, (C) acrylic resin and (D) oxyalkylene polymer, and optionally carbon black, and after mixing, melt kneading using a 30 mm twin-screw extruder to form pellets. A composition of the form was prepared. Then, a test piece was molded from the pellet using an injection molding machine, and the weather resistance and other characteristics were measured and evaluated. For comparison,
The case where the (B) weather resistance (light) stabilizer was added alone or in combination with the (C) acrylic resin or the (D) oxyalkylene polymer (in some cases, carbon black) was similarly prepared and evaluated.

[Effects of the Invention] As is clear from the above description and examples, the polyacetal resin of the present invention is obtained by adding and blending a weathering (light) stabilizer, a specific acrylic resin and an oxyalkylene polymer in combination. The composition has a surface condition when exposed to ultraviolet rays or water for a long time, as compared with a composition not using these components in combination,
In particular, the crack generation time is extremely delayed, the gloss retention rate is high, and the discoloration is reduced, and the mechanical properties (tensile elongation and Izod), which are drawbacks when using conventional acrylic resins, are exhibited. The impact strength) has been reduced and the moldability has been improved.

Therefore, the weather-resistant polyacetal resin composition of the present invention is a molded part for all fields requiring weather resistance (light), that is, exterior parts of automobiles (for example, outer handle, fuel lid, wheel cover, front fender, spoiler, etc.), interior parts. Suitable for parts (for example, inner handle, regulator handle, etc.), electrical equipment, cameras, parts of other industrial products, building material piping, sundries, household items, etc. that are exposed to sunlight, rain, etc. for a long time Can be used for

Claims (5)

[Claims] 1. A polyacetal resin (A), (B) 0.01 to 5% by weight of a weathering (light) stabilizer (based on the total composition).
And (C) 1 to 40% by weight of acrylic resin (relative to the total composition) and (D) 0.1 to 10% by weight of oxyalkylene polymer having 2 to 8 adjacent carbon chains (relative to the total composition). A weather-resistant polyacetal resin composition comprising: 2. The weather-resistant polyacetal resin composition according to claim 1, wherein the acrylic resin (C) is a methyl methacrylate homopolymer or a methyl methacrylate copolymer containing this as a main component. 3. The (B) weathering (light) stabilizer is selected from the group consisting of benzotriazole type substances, benzophenone type substances, aromatic benzoate type substances, cyanoacrylate type substances, oxalic acid anilide type substances and hindered amine type substances. The weather-resistant polyacetal resin composition according to claim 1, which is one kind or two or more kinds. 4. The (B) weather-resistant (light) stabilizer is one or more of benzotriazole-based substances, benzophenone-based substances, aromatic benzoate-based substances, cyanoacrylate-based substances or oxalic acid anilide-based substances, and hindered amine-based substances. The weather-resistant polyacetal resin composition according to claim 1, which is used in combination with a substance. 5. The oxyalkylene polymer (D) is one or more selected from the group consisting of poly (ethylene oxide), poly (propylene oxide) and ethylene oxide / propylene oxide copolymer. The weather resistant polyacetal resin composition of.