JPH0726109A - Polyacetal resin composition - Google Patents

Abstract

PURPOSE:To obtain a polyacetal resin composition, capable of suppressing the deterioration and discoloration of a resin and bleeding and discoloration of an additive as much as possible in exposure to light for a long period, capable of retaining the initial surface conditions of moldings and excellent in weather and environmental resistance. CONSTITUTION:This polyacetal resin composition is obtained by adding and blending (B) 0.01-2.0 pts.wt. ultraviolet ray absorber and (C) (C-1) 0.01-1 pt.wt. low-molecular weight hindered amine-based substance having <700 molecular weight and (C-2) 0.01-4 pts.wt. high-molecular weight hindered amine-based substance having >=700 molecular weight with (A) 100 pts.wt. polyacetal resin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyacetal resin composition having excellent weather (light) resistance. More specifically, by combining a polyacetal resin with an ultraviolet absorber and two specific hindered amine light stabilizers, it is possible to minimize discoloration and gloss deterioration due to resin deterioration and additive leaching during long-term light exposure, and to minimize initial The present invention provides a polyacetal resin composition which maintains the surface condition of the molded article and is excellent in weather resistance and environment resistance.

[0002]

2. Description of the Related Art As is well known, a polyacetal resin is an engineering material having excellent physical properties such as mechanical properties and electrical properties, or chemical properties such as chemical resistance and heat resistance. Recently, it has been used as a resin in an extremely wide range of fields. 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 lose their discoloration and surface smoothness on the surface of molded articles due to the atmosphere used for a long period of time such as sunlight, moisture (rain, condensation, etc.) and other atmospheric contact. As a result, a decrease in gloss may occur, and further cracks may occur on the surface of the component, which may impair the external appearance. To prevent these drawbacks,
Conventionally, it has been proposed to add various weather resistance (light) stabilizers to a polyacetal resin to improve the weather resistance (light) of the polyacetal resin. In particular, it is known that the combined use of various ultraviolet absorbers and hindered amine light stabilizers has an effect on weather resistance (light). However, it is necessary to add a large amount of the above additives in order to maintain long-term weather resistance (light resistance). However, addition of a large amount leads to deterioration of mechanical properties, and at the time of molding, there are problems such as dimensional defects due to adhesion and deposition on the mold (so-called mold deposit), poor appearance of molded products, etc. There is. Furthermore, in the case of polyacetal resin, because it is a highly crystalline polymer, the additive oozes out due to recrystallization due to heat and temperature difference (condensation) in the exposure environment, causing discoloration of the surface of the molded product and decrease in gloss. Behaviorally similar to resin deterioration. Especially, for automobile interior parts, which are used under extremely high temperature or high humidity environment, for example, the effect thereof is great, and addition of a large amount of additive causes a deterioration of the appearance of the surface of the molded product. Therefore, there has been a demand for the development of a polyacetal resin material which maintains the weather resistance (light resistance), does not exude the additive, and maintains the appearance of the molded product for a long period of time.

[0003]

[Means for Solving the Problems] The present inventors have maintained the excellent weather resistance (light) resistance without sacrificing the original properties of the polyacetal resin, and suppress the surface discoloration due to the exudation of additives as much as possible. The present invention has been completed as a result of intensive research to develop a polyacetal resin composition in which the initial surface state of a molded product is maintained for a long period of time. That is, the present invention is (A) 100 parts by weight of polyacetal resin (B) 0.01 to 2.0 parts by weight of an ultraviolet absorber and (C) a low molecular weight hindered amine-based substance (C-1) having a molecular weight of less than 700.
A polyacetal resin composition comprising 0.01 to 1 part by weight and 0.01 to 4 parts by weight of a high molecular weight hindered amine-based substance (C-2) having a molecular weight of 700 or more.

The constituent components of the present invention will be described in detail below. First, 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 a polyoxymethylene homopolymer and other constituent units other than the oxymethylene group. It may be a copolymer, a terpolymer or a block copolymer having a small amount of, and the molecule may have not only a linear structure but also a branched or crosslinked structure. There is no particular limitation on the degree of polymerization or the like.

Next, among (B) UV absorbers used in the present invention, preferably used are benzotriazole type substances, benzophenone type substances, aromatic benzoate type substances, cyanoacrylate type substances, oxalic acid anilide type substances, etc. Among them, benzotriazole-based substances and / or benzophenone-based substances are preferable. Among these, examples of particularly preferable 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. Further, as the benzophenone-based substance, 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-4-oxybenzylbenzophenone and the like can be mentioned. The amount of the ultraviolet absorbent (B) used here is preferably 0.01 to 2 parts by weight (100 parts by weight of the polyacetal resin), particularly 0.05 to 1 part.
Parts by weight are preferred. If the component (B) is too small, no effect can be expected, and even if it is added unnecessarily excessively, not only is it economically disadvantageous, but it also causes problems such as deterioration of mechanical properties and mold contamination. Become.

Even if such an ultraviolet absorber (B) is blended with the polyacetal resin (A) alone, the weather (light) resistance is not sufficiently improved, and it is generally used in combination with a hindered amine-based substance. However, as described above, even such a polyacetal resin composition does not always have sufficient weather resistance (light) depending on the use conditions, and even if the amount of the weather resistance stabilizer is increased, the effect of improving the weather resistance is expected for the amount. Can not.
In addition, when a large amount of weather resistance stabilizer is used, the temperature difference is relatively large, as in the interior of an automobile, and under the environmental conditions where dew condensation is likely to occur, stabilizer bleeding is observed and it accumulates on the surface of molded products, causing surface changes (whitening). In addition, the gloss is deteriorated, and as a result, the initial surface condition is impaired.

Therefore, the present invention relates to a hindered amine-based substance
As the (C), two kinds having different molecular weights are used, which are used in combination with the above-mentioned ultraviolet absorber (B) to obtain the polyacetal resin (A).
It is characterized in that it is excellent in weathering (light) resistance due to such blending, and discoloration of the surface of the molded product due to exudation caused by stabilizers such as hindered amine-based substances.
It is intended to provide a polyacetal resin composition capable of suppressing deterioration of gloss and maintaining an initial surface state even under a long-term light exposure environment. Two (C) hindered amine-based substances with different molecular weights used for this purpose are low molecular weight hindered amine-based substances (C-1) with a molecular weight of less than 700 and the other with a molecular weight of 700.
The above high molecular weight hindered amine-based substances (C-2) are used alone or in combination of two or more in the present invention.
Examples of low molecular weight hindered amine type substances (C-1) having a molecular weight of less than 700 used here are 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. A hindered amine-based substance having a molecular weight of 600 or less is preferable, and bis (2,2,6,6-tetramethyl-
4-piperidyl) sebacate and bis (1-methyl-2,2,
6,6-Tetramethyl-4-piperidyl) adipate is preferably used. Next, an example of a high molecular weight hindered amine-based substance (C-2) having a molecular weight of 700 or more is tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4
-Butane tetracarboxylate, tetrakis (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) 1,2,
3,4-Butane tetracarboxylate, 1- [2- {3
-(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, or a piperidine derivative condensate, for example Dimethyl succinate-1
-(2-hydroxyethyl) -4-hydroxy-2,2,6,
6-Tetramethylpiperidine polycondensate, poly [[6-
(1,1,3,3-Tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-
4-piperidyl) imino] hexamethylene [(2,2,6,6
-Tetramethyl-4-piperidyl) imino]] (molecular weight
2500 or more), poly [(6-morpholino-S-triazine-2,4-diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6 -Tetramethyl-4-piperidyl) imino] (molecular weight 1400 to 17
00) and the like. A high molecular weight hindered amine compound having a molecular weight of 1000 or more is preferable, and poly [(6-
Morpholino-S-triazine-2,4-diyl) (2,2,
6,6-Tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino] (molecular weight 1400-1700) and dimethyl succinate-1- (2- Hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (molecular weight
3000 or more) is preferably used.

Hindered amine-based material used here
The amount of (C) added is low molecular weight (C-1) with a molecular weight of less than 700.
0.01 to 1.0 parts by weight (compared to 100 parts by weight of polyacetal resin), 0.01 to 4.0 for high molecular weight compounds (C-2) with a molecular weight of 700 or more.
A suitable weight part is 0.02 to 5.0 parts by weight as the total amount of the two kinds of hindered amine-based substances. Especially (C-1)
Is preferably 0.02 to 1 part by weight, and (C-2) is preferably 0.03 to 1.5 parts by weight. The ratio of (C-1) to (C-2) is preferably 1: 1 to 1: 5. If these components are too small, no effect can be expected, and if they are added too much, bleeding occurs, resulting in impairing the initial molding surface condition which is the object of the present invention. In particular, when a low molecular weight hindered amine-based substance (C-1) is added in excess, not only exudation and discoloration increase, surface deterioration becomes noticeable, but also mechanical properties decrease, mold contamination (so-called mold deposit), etc. Has the problem of. Two kinds of hindered amine type substances (C) having different molecular weights
When used in combination with the ultraviolet absorber (B), it produces a sufficient effect for improving the weather resistance, particularly for preventing cracks on the surface of the molded product and for preventing discoloration of the surface of the molded product due to long-term exposure.

The action and effect are considered as follows.
First, the hindered amine-based substance captures and stabilizes radicals generated on the surface of the molded product due to the effects of light, heat, and the like.
The hindered amine on the surface is deactivated by long-term light irradiation, but the hindered amine scattered inside oozes out on the surface due to temperature change. Although it is light-stabilized by this, the surface of the molded product is discolored because the low-molecular-weight substance having a high volatility as described above bleeds out too much. On the other hand, a low volatility high molecular weight substance causes the exudation speed to be too slow, so that the surface of the molded product is photo-deteriorated. Therefore, as a result of evaluating various amounts of exudation and discoloration level, a molecular weight of 700 was used as a boundary,
It is considered that the combined use of the hindered amine compound before and after that suppresses discoloration due to exudation and has excellent weather resistance to long-term light exposure.

Further, the composition of the present invention can be blended with (D) a coloring component to obtain a colored molded body which does not require a plating layer or a coating layer. As the coloring component, various carbon blacks and various dyes and pigments are used. Among them, the addition of carbon black further improves the weather resistance of the composition. The amount of the coloring component used here is 0.1 to 4 with respect to 100 parts by weight of the polyacetal resin.
Parts by weight, preferably 0.2-2 parts by weight. (A) ~ (C)
Colored molded products with (D) coloring component added to the component can suppress discoloration and lowering of gloss due to photodegradation and exudation of stabilizer under a long-term light exposure environment, and can maintain the initial color and luster level. Is.

To the composition of the present invention, it is desirable to add various known stabilizers to reinforce the thermal stability. For this purpose, known antioxidants, nitrogen-containing compounds, alkali or alkaline earth metal compounds are known. It is desirable to use one kind or a combination of two or more kinds. Further, in order to add 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 polymers are used. One, two or more kinds of materials, inorganic, organic fibrous, powdery, plate-like fillers and the like can be added and contained.

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 the 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. Further, 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 just before obtaining the final molded product. Further, the resin composition according to the present invention, extrusion molding, injection molding,
It can be formed by any of compression molding, vacuum molding, blow molding, and foam molding.

[0013]

EXAMPLES The present invention will now be described with reference to examples, but the present invention is not limited thereto. The methods used for evaluation of the weather resistance test in the examples are as follows. [Weather resistance test] Xenon weather meter [XE manufactured by Suga Test Instruments Co., Ltd.
L-2WN type] was tested under the following light-dark cycle conditions. Light irradiation 3.8 Hrs / 89 ° C, 50% RH dark 1.0 Hrs / 38 ° C, 95% RH Long-term sunlight exposure was carried out by an underglass exposure (completely sealed method) test in Okinawa. In the above test, the change of the surface condition and the crack generation time were evaluated. (a) Crack generation time The test piece was exposed under predetermined conditions, and the presence or absence of cracks on the surface of the test piece was observed with a 10 times magnifying glass. The larger the value, the better. (b) Change of surface condition-1, 2 (confirmation of exudation state) The test piece is exposed for a certain period of time under a predetermined condition, and the change in hue, change in gloss and crack of the test piece before and after the exposure are observed, The degree of those changes is divided into five levels and displayed. The smaller the number, the smaller the change, that is, the less the color change, the change in gloss and the occurrence of cracks. The change in surface condition was evaluated in the following two stages. 1. The test piece after the exposure treatment was directly observed and evaluated. 2. In order to remove the discoloration factor due to bleeding, the surface of the test piece after the exposure treatment was washed with a water cloth and then observed and evaluated. That is, when the score is high in the change of the surface state-1 and low in the change of the surface state-2, it is considered that the discoloration factor due to the exudation is large, and both of the change-1 and the change-2 are large. When the score is high, deterioration due to weather resistance is considered to be the main factor.

Examples 1 to 13 and Comparative Examples 1 to 14 As shown in Table 1, (A) polyacetal resin (manufactured by Polyplastics Co., Ltd., trade name "DURACON") is added with (B) an ultraviolet absorber and (C). ) Two kinds of hindered amine compounds were mixed and then melt-kneaded using a 30 mm twin-screw extruder to prepare a pelletized composition. Then, a test piece was molded from the pellet using an injection molding machine, and weather resistance and other characteristics were measured and evaluated. For comparison, as shown in Table 2,
A composition was prepared and evaluated in the same manner for the component (B) alone or the component added except for the compound of one of the components (C). The results are shown in Tables 1 and 2.

[0015]

[Table 1]

[0016]

[Table 2]

Note 1 B-1; 2- [2-hydroxy-3,5-bis (α, α-
Dimethylbenzyl) phenyl] benzotriazole B-2; 2-hydroxy-4-oxybenzylbenzophenone Note 2 Low molecular weight hindered amine compound C-1; Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (molecular weight 481) C-2; bis (1-methyl-2,2,6,6-tetramethyl-
4-piperidyl) adipate (molecular weight 453) Note 3 High molecular weight hindered amine compound C-3; poly [(6-morpholino-S-triazine-
2,4-Diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino] (molecular weight about 1600) C-4; dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (molecular weight 3000 or more) C-5; tetrakis (2,2,2) 6,6-Tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate (molecular weight 792) Note 4 D-1; carbon black D-2; quinacridone red

[0018]

As is clear from the above description and examples, a polyacetal resin is used in combination with an ultraviolet absorber and two kinds of hindered amine compounds having different molecular weights,
The composition of the present invention, which is added and blended, keeps the initial surface state of the polyacetal molded article by suppressing discoloration / gloss reduction due to seepage of the stabilizer even under a long-term light exposure environment, It showed a remarkable effect of remarkably improving the weather resistance. Therefore, the composition of the present invention can be used as an automobile interior component (for example, a regulator handle, an interior clip, a ventilator knob, etc.), and an automobile by taking advantage of its excellent weather resistance (light) property and the property of retaining an initial surface state. It can be suitably used for applications such as outer handles, keyboard key tops, optical machines, housings, household articles, and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C08L 71:02)

Claims (6)

[Claims] Claims: (A) 100 parts by weight of polyacetal resin (B)
UV absorber 0.01 to 2.0 parts by weight and (C) molecular weight 7
Low molecular weight hindered amine-based substance (C-1) less than 00 0.01 ~
A polyacetal resin composition comprising 1 part by weight and 0.01 to 4 parts by weight of a high molecular weight hindered amine substance (C-2) having a molecular weight of 700 or more. 2. The polyacetal resin composition according to claim 1, wherein the ultraviolet absorbent (B) is a benzotriazole-based substance and / or a benzophenone-based substance. 3. The compounding amount of the (C-1) low molecular weight hindered amine-based substance is 0.02 to 1 part by weight (100 parts by weight of the polyacetal resin), and the compounding amount of the (C-2) high molecular weight hindered amine-based substance is 0.03. ~ 1.5 parts by weight (to polyacetal resin 1
(00 parts by weight), The polyacetal resin composition according to claim 1 or 2. 4. The polyacetal resin composition according to claim 1, wherein the high molecular weight hindered amine-based substance (C-2) has a molecular weight of 1000 or more. (C) The total amount of the two kinds of hindered amine-based substances added is 0.02 to 5.0 parts by weight (100 parts by weight of the polyacetal resin), and the low molecular weight product (C-1) and the high molecular weight product (C) are used. -
The addition ratio with 2) is 1: 1 to 1: 5.
The polyacetal resin composition according to claim 1. 6. A colored polyacetal resin composition obtained by adding 0.1 to 4 parts by weight of (D) a coloring component (100 parts by weight to polyacetal resin) to the composition according to any one of claims 1 to 5. object.