JPH03126752A - Polyoxymethylene resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in surface appearance, crystallinity, mechanical strength and heat aging resistance by blending a polyoxymethylene resin with an aliphatic polyether and/or aliphatic polyester. CONSTITUTION:A polyoxymethylene resin composition obtained by blending (A) 100 pts.wt. polyoxymethylene resin with (B) 0.001-50 pts.wt. polyoxymethylene copolymer having copolymerization units expressed by the formula ((m) and (n) are 0-20; (m+n)>1; R is reactive group without branching) and (C) an aliphatic polyether and/or an aliphatic polyester in an amount of 0.01-20 pts.wt. The group R in the formula of the component (B) is selected from alkyl, alkoxy, aryl, aryloxyalkyl and aryloxy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyoxymethylene resin composition having excellent surface appearance, crystallinity, mechanical strength, and heat aging resistance.

[Prior Art] Polyoxymethylene resin is known as an engineering plastic with a good balance of mechanical strength and impact resistance, and is used in a wide range of fields as automobile parts and parts for electronic devices.

However, polyoxymethylene resin has extremely high crystallinity, and as a result, the spherulite structure that grows significantly especially when heat treated causes cracks and internal strain, thereby reducing the mechanical strength of the resin. Conventionally, as a method to refine and homogenize the crystal structure of polyoxymethylene resin, blending nucleating agents made of various inorganic compounds, organic compounds, and polymeric compounds with polyoxymethylene resin has been carried out. . For example, as an inorganic nucleating agent,
Polyoxymethylene resin compositions containing talc (Japanese Patent Publication No. 48-8254) and polyoxymethylene resin compositions using branched or linear polyoxymethylene as a nucleating agent are known. (Tokuko Showa 5)
Furthermore, compositions of branched or networked polyoxymethylene and polymers having a softening point below polyoxymethylene and an average molecular weight of 1,000 to 1,000,000 are also known (Japanese Patent Publication No. 58-42823). )
.

[Problems to be Solved by the Invention] However, the resin compositions described in the above-mentioned Japanese Patent Publication No. 48-8254, Japanese Patent Publication No. 55-19942, and Japanese Patent Publication No. 5642623 have problems with the crystal structure of the obtained molded product. Due to insufficient miniaturization and homogenization, as well as insufficient relaxation of internal strain, a decrease in mechanical strength during heat treatment becomes a problem. It does not satisfy high durability.

[Means for Solving the Problems] As a result of intensive studies by the present inventors to solve the above problems,
A resin composition obtained by blending an oxymethylene copolymer having a specific copolymerized unit with an aliphatic polyether and/or an aliphatic polyester in a polyoxymethylene resin has an extremely fine and homogeneous crystal structure, It has been discovered that a molded product with reduced internal strain and excellent mechanical strength and surface appearance can be obtained, leading to the present invention.

That is, the present invention provides (a) polyoxymethylene resin 10
(b) 0 parts by weight of a polyoxymethylene copolymer having a copolymerized unit represented by the following general formula (1)
．． 001 to 50 parts by weight, (CH2)--CH-(CH2
) n-〇-CI) (however, m and n are O~20
represents an integer of m+n>1. R represents a reactive and unreactive group. ) and (C) aliphatic polyether and/or aliphatic polyester 0.01 to 20 parts by weight.

The polyoxymethylene resin as component (a) used in the present invention is a polyoxymethylene homopolymer or an oxyalkylene unit mainly composed of oxymethylene units and having 2 to 8 adjacent carbon atoms in the main chain. means a polyoxymethylene copolymer containing 15% by weight or less of

A polyoxymethylene homopolymer is produced, for example, by introducing substantially anhydrous formaldehyde into an organic solvent containing a basic polymerization catalyst such as an organic atom, polymerizing it, and then acetylating the terminals with acetic anhydride. be able to.

Polyoxymethylene copolymers are prepared by dissolving or suspending substantially anhydrous trioxane and copolymer components such as ethylene oxide, 1,3-dioxolane, and L3-dioxolane in an organic solvent such as cyclohexane. After that, a Lewis acid catalyst such as boron trifluoride/diethyl etherate is added to polymerize, and unstable terminals are decomposed and removed. Preferably, a premix of hetrioxane and copolymerization component/catalyst is introduced into a self-cleaning stirrer without using any solvent, and bulk polymerization is carried out. After the catalyst is deactivated with a hindered door, unstable terminals are decomposed. A method of manufacturing by removing it can be adopted.

Furthermore, the polyoxymethylene copolymer having copolymerized units represented by the formula (I) as component (b) used in the present invention includes, for example, (1) substantially anhydrous trioxane and ethylene oxide or propylene oxide. , 1.3-dioxolane,
1,3-dioxane, 1,3-dioxolane, 1.
3. 5-) at least one compound selected from rioxeban, 1,3゜e-trioxocane, and epichlorohydrin and a cyclic ether compound represented by the following general formula (]I); (2) substantially anhydrous trioxane and the following general compound; A cyclic ether compound represented by formula (n) (where m and n represent an integer of O to 20, m+n≧
It is 1. R represents a reactive and unreactive group. ) can be produced by polymerizing by adding a Lewis acid catalyst such as boron trifluoride diethyl etherate and decomposing and removing unstable terminals. bulk polymerization using a self-cleaning stirrer, preferably without using any solvent;
An example of this method is to deactivate the catalyst with a hindered compound and then decompose the unstable end.

Among the cyclic ether compounds represented by the above general formula (I[), particularly preferred compounds include phenyl glycidyl ether, styrene oxide, naphthyl glycidyl ether, and the like. The amount of the cyclic ether compound represented by the general formula (n) to be copolymerized is preferably 0.001 to 1 part by weight, particularly preferably 0.01 to 5 parts by weight, per 100 parts by weight of trioxane. If it is less than 0.001 part by weight, the relaxation of mold strain is small, and if it is more than 10 parts by weight, the impact strength is decreased and the polymer yield is poor.
This is not preferable because it reduces productivity.

Copolymerization of copolymer components such as polyoxymethylene copolymer, which is part of component (a) of the present invention, and ethylene oxide used in the above (1), which is part of component (b), such as 1,3 dioxolane. The amount is 0 per 100 parts by weight of trioxane.
．． 01 to 20 parts by weight, preferably 0.01 to 20 parts by weight. It is 1 to 7 parts by weight.

If it is less than 0.01 parts by weight, the polymer yield during thermal stabilization tends to decrease, and if it is more than 20 parts by weight, it is difficult to obtain a polymer with excellent mechanical strength.

Similarly, the amount of polymerization catalyst added is 0.001 to 0.00 parts by weight per 100 parts by weight of trioxane. The range is preferably 1 part by weight, particularly preferably 0.005 to 0.05 parts by weight.

Moreover, the bulk polymerization reaction temperature is preferably in the range of 610-120°C, particularly preferably in the range of 60-9°C. After polymerization, it is preferable to deactivate the catalyst in a hindered door and then decompose and remove unstable terminals.

The aliphatic polyether used as component (c) in the present invention includes poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(ethylene oxide/propylene oxide) glycol, poly( Ethylene oxide/
Examples include tetramethylene oxide) glycol, ethylene oxide adducts of poly(propylene oxide fuglycol), and derivatives thereof.

The average molecular weight of the aliphatic polyether is 100-5
It is preferably in the range of 0,000, particularly preferably 1
The range is from 000 to 30,000.

If the average molecular weight is less than 100, the aliphatic polyether will bleed onto the surface of the molded product, reducing its commercial value, which is not preferable. Moreover, in the case of 50,000 or more, the relaxation of Kai type strain is small and the decrease in mechanical strength is large, so it is not used.

In addition, the aliphatic polyester of component (c) used in the present invention is a polyester consisting of an aliphatic dicarboxylic acid having 4 to 20 carbon atoms and an aliphatic diol having 2 to 10 carbon atoms, and a ring-opening polymerization of lactones. Specific examples thereof include poly(ethylene adipate), poly(butylene adipate), poly(ethylene sebacate), poly(butylene sebacate), and poly(ε-caprolactone).

The average molecular weight of the aliphatic polyester is 1°O~5
It is preferably in the range of 0,000, particularly preferably 1
The range is from 000 to 30,000.

If the average molecular weight is less than 100, the aliphatic polyester will bleed onto the surface of the molded product, reducing its commercial value, which is not preferable. Moreover, if it is 50,000 or more, the relaxation of molding strain is small and the mechanical strength is greatly reduced, so it is not used.

In the present invention, component (b), a polyoxymethylene copolymer having copolymerized units represented by formula (I), and component (C), aliphatic polyether and/or aliphatic polyester, are added to the polyoxymethylene resin. Only when they are added in combination can a polyoxymethylene resin with reduced distortion and excellent surface appearance, crystallinity, mechanical strength, and heat aging resistance be obtained.

The amount of the polyoxymethylene copolymer having a copolymerized unit represented by the formula (I), component (b), used in the present invention is 0 parts by weight per 100 parts by weight of the polyoxymethylene resin, component (a). The amount is from .001 to 50 parts by weight, preferably from o, oi to 3o parts by weight. If it is less than 0.001 parts by weight, the effect of improving Ilj and mold distortion will be small, and if it is more than 50 parts by weight, mechanical strength, typified by impact strength, will decrease, which is not preferable. In addition, in the present invention, (b) 4 minutes (
In addition to the polyoxymethylene copolymer having the copolymerized unit represented by the formula I), it is important to add an aliphatic polyether and/or an aliphatic polyester as the component (c). The amount of aliphatic polyether and/or aliphatic polyester added is 0.0 parts by weight per 100 parts by weight of the polyoxymethylene resin of component (a).
The amount is 1 to 20 parts by weight, preferably 0.05 to 10 parts by weight.

If it is less than 0.01 part by weight, the effect of improving shape distortion is small;
If it is more than 0 parts by weight, mechanical strength represented by tensile strength decreases, which is not preferable.

As a method for producing the polyoxymethylene resin composition of the present invention, generally known methods can be employed. For example, (a)
In the polymerization or stabilization step of component polyoxymethylene resin, (b) component polyoxymethylene copolymer having copolymerized units represented by general formula (1) and (c) component aliphatic polyether and/or A method of adding an aliphatic polyester, (a) a polyoxymethylene resin as a component, (b) a polyoxymethylene copolymer having a copolymerized unit represented by the general formula (I) as a component, and (C)
The component aliphatic polyether and/or fatty 1-aliphatic polyester may be mixed in the form of pellets, powder, or granules and melt-processed as is. A method can also be adopted. Particularly preferred is a method of melt-mixing at a temperature of 150 to 250°C using a single-screw or twin-screw extruder.

In addition, the composition of the present invention may contain fillers such as calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, mica powder, glass peas, carbon fiber, glass fiber, and ceramics within a range that does not impair the effects of the present invention. Reinforcing agents such as Kutsuku fiber, Arakudo fiber, Potassium titanate fiber, Coloring agents (pigments, dyes), Nucleating agents, Plasticizers, Mold release agents such as ethylene bis stearamide, polyethylene wax, Carbon black conductive agents such as hindered phenolic compounds, thioether compounds, antioxidants such as phosphite compounds, light stabilizers such as hindered phenolic compounds, benzophenone compounds, benzotriazole compounds, melacone, guanidine, etc. Optionally, additives such as formalde 2-human scavengers, adhesives, lubricants, hydrolysis resistance modifiers, adhesion aids, etc., such as nylon, dicyanthiade, etc., may be included.

The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

[Example] The present invention will be explained below with reference to Examples. Note that all percentages and parts in the examples are based on weight.

Further, the mechanical properties, MI value, polymer melting point, crystallization temperature, and heat aging resistance of the molded articles shown in Examples and Comparative Examples were measured as follows.

・Bottom shape: Using an injection molding machine with a 5 oz injection capacity, the cylinder temperature was set at 190°C, the mold temperature was set at 65°C, and the molding cycle was set at 50 seconds. was injection molded. On this occasion,
The appearance of the ASTMI dumbbell test piece was visually observed.

・Mechanical properties: Using the ASTMI dumbbell test piece obtained by the above injection molding, the tensile strength was measured according to the ASTM-D638 method. Also, using the Izotsu impact test piece, the AST
Impact strength was measured according to MD-25El method.

- MI value 2 Using pellets dried for 3 hours in a hot air oven at 80°C, it was measured according to ASTM-D1238 at a temperature of 190°C and a load of 2190 grams.

・Melting point (Tm), crystallization temperature (Tc): Using a differential scanning calorimeter (DSC), raise the temperature from 80°C to 220°C at a rate of 10°C/min in a nitrogen atmosphere and hold at 220°C for 5 minutes.
The temperature was then lowered at a rate of 10° C./min, and the crystallization temperature was measured. Furthermore, after cooling to 110℃, it was heated again to 10℃.
The melting point was measured by increasing the temperature at a rate of °C/min.

・Heat aging resistance: AST obtained by the above injection molding
The No. MI dumbbell was placed in an oven set at 150° C., and after a predetermined period of time, it was taken out and its tensile strength was measured according to ASTM D638 method.

The polyoxymethylene resin used in the Examples and Comparative Examples was manufactured by the following method.

・Production of polyoxymethylene resin POM-1 Trioxane (22,5
kg/h), 1,3-dioxolane (700g/h
), *loopppm of boron trifluoride diethyl etherate (2.5% solution in benzene) for trioxane
, 500 ppm of methylal were respectively supplied to carry out continuous polymerization. Polymerization was carried out with the external jacket temperature controlled at 60° C. and the rotation speed at 1100 rpm. Methyral as a molecular weight regulator was dissolved in trioxane. Further, a premixing zone was provided so that 1,3-dioxolane and the catalyst solution were premixed immediately before being supplied to the kneader. 22.3 kg of polymer as white fine powder
/h.

For 5 kg of fine powder obtained in this way, 13.5
'5unol' L S 785 (Cib
A solution of bis(1,2,8,6-pentamethyl-4piperidinyl)sebacate, manufactured by a-Geigy, dissolved in 20 ml of benzene was added, and the mixture was stirred for 10 minutes in a Henschel mixer to deactivate the catalyst. After that, lrga5-nox245 (manufactured by Ciba-Geigy, [triethylenedi-1-nocolubis[3-(3-t-butyl-5-methyl=4-hydroxyphenyl)propionate]) 25g1 Calcium stearate 5g1 Melayone 5g was added. Heat and melt at 210℃ for 10 minutes,
0M-1 was obtained.

・Production of polyoxymethylene resin POM-2 A polymerization reaction tank having a diameter of 30 cm and a depth of 3 meters and equipped with a bottom stirring blade and a formaldehyde supply nozzle was filled with n-hexane. In this, 0.0% of shikodi n-butyltin dimaleate was added. 5 parts by weight were dissolved, and formaldehyde gas was introduced from the supply nozzle. The formaldehyde gas used was purified formaldehyde.1. It was introduced at a rate of 5 kg/h. The temperature inside the polymerization tank was adjusted to 50° C. by flowing cold or hot water through the jacket. There is a force that gradually generates polymer fine particles in the polymerization tank (the solid content of polymerization is about 5
During the polymerization, the slurry was kept at 0% by weight and the catalyst solution (n-hexane) 1b was supplied. The extracted polymer was filtered, thoroughly washed with water, and then poured into acetic anhydride in an amount 10 times the amount of the polymer. Furthermore, sodium acetate was added to 0.0% of acetic anhydride. 1% by weight
The mixture was then heated and stirred at 139°C for 5 hours. After the reaction mixture cooled to room temperature, the polymer was filtered off, thoroughly washed with acetone and water, and then dried to obtain Po11-2.

- Production of oxymethylene copolymer having copolymerized units represented by general formula (I) MI by adding a cyclic ether represented by general formula (n), which is a copolymerized unit, and changing the amount of methylal added. 9
．． Polymerization was carried out in the same manner as POM-1 except that the amount was adjusted to 0 g/10 minutes. This cyclic ether is directly pumped into 2
It was supplied to a shaft extruder type polymerization machine.

・Manufacture of branched POM 1.4-butanediol diglycidyl ether, which is a copolymerization unit, is added to 0.00 parts by weight per 100 parts by weight of trioxane.
It was added to a twin-screw extruder type polymerizer using a pump at a ratio of 5 parts by weight, and polymerized in the same manner as ROM-1. The resulting branch P
The melting point of OM was 162°C, and the Ml was 2-1 g/10 min.

・Examples 1 to 14 and Comparative Examples 1 to 7 POM 1 to 2 of the polyoxymethylene resin of the component (a), POM (oxymethylene copolymer) having copolymerized units of general formula (1) of the component (b) A tri-blend of aliphatic polyether and aliphatic polyester as components (combined) and (C) was melt-kneaded at 220°C in a vented twin-screw extruder with a diameter of 45 mm and L/D = 31.5, and the mixture was discharged into water and cut. and got a beret.

Table 1. ~Table 3. (a), (b) and (c) used for
) The types and blending ratios of the components and the obtained physical properties are shown. Table 1. ~Table 3. The results show that the composition of the present invention has excellent surface appearance, excellent crystallinity due to the small difference between melting point (Tm) and crystallization temperature (Tc), and excellent mechanical strength and heat aging resistance. It's obvious.

Margin 9 below - [Effects of the Invention] The present invention provides improved mechanical strength by blending an oxymethylene copolymer having a copolymerized unit represented by the general formula CI) with an aliphatic polyether and/or an aliphatic polyester. Since a polyoxymethylene resin composition with excellent surface appearance and heat aging resistance can be obtained, it is widely used for mechanical parts in the electric/electronic field, automobile field, etc.

Claims (3)

[Claims] (1) Based on 100 parts by weight of (a) polyoxymethylene resin, (b) 0.001 to 5 parts of polyoxymethylene copolymer having copolymerized units represented by the following general formula (I)
0 parts by weight, ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (However, m and n represent integers from 0 to 20, m+n>
It is 1. R represents a reactive, unbranched group. ) and (c) a polyoxymethylene resin composition containing 0.01 to 20 parts by weight of an aliphatic polyether and/or an aliphatic polyester. (2) In a polyoxymethylene copolymer having a copolymerized unit represented by general formula (I), R is an alkyl group, an alkoxyalkyl group, an alkoxy group, an aryl group,
The resin composition according to claim 1, which is at least one selected from aryloxyalkyl groups and aryloxy groups. (3) In the oxymethylene copolymer having copolymerized units represented by general formula (I), R is CH_2OPh
, Ph, CH_2ONp, Np (Ph is phenyl group, N
p means a naphthyl group)
The resin composition according to claim 1, which is a seed.