JPH04266917A - Oxymethylene multicomponent copolymer - Google Patents

Abstract

PURPOSE:To obtain the title copolymer having high cycle moldability during injection molding and excellent mechanical properties, comprising trioxan, a specific cyclic ether compound and a specific compound such as styrene oxide. CONSTITUTION:The objective copolymer which is an oxymethylene multicomponent copolymer obtained by copolymerizing (A) trioxan with (B) a cyclic ether compound selected from ethylene oxide, 1,3-dioxolan, 1,3-dioxepan, 1,3,5-trioxepan and 1,3,6-trioxocane and (C) a compound selected from glycidyl phenyl ether, styrene oxide and glycidyl naphthyl ether, has correlation between a melting point Tm and temperature dropping crystallization temperature Tc satisfying the formula 15<=Tm-Tc<25( deg.C) and <=30mum spherulite size. The copolymer is preferably obtained by subjecting the components A, B and C to bulk polymerization under stirring by a self-cleaning type stirrer without using a solvent at all, deactivating a catalyst with a hindered amine compound and decomposing and removing unstable polymer ends.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxymethylene multi-component copolymer which exhibits excellent high cycle performance and mechanical properties during injection molding.

More specifically, oxymethylene has a high solidification temperature in the mold during injection molding, so it can be molded in a short cycle time, and its small spherulite size reduces molding distortion, resulting in excellent mechanical properties. It relates to multi-component copolymers.

0003

BACKGROUND OF THE INVENTION Polyoxymethylene resins are known as engineering plastics with a good balance of mechanical strength and impact resistance, and are used in a wide range of fields as parts for automobiles and electronic devices.

Polyoxymethylene resins are mostly processed by injection molding. In the field of injection molding, there is a strong demand for improved productivity by shortening the molding cycle, so-called high cycle.

[0005] To increase the cycle speed of polyoxymethylene resin, which is a crystalline polymer, a method has been proposed in which a nucleating agent is added to increase the crystallization rate and solidification rate in the mold. . For example, JP-A-59-129247 and JP-B-55-19942 describe a method using a polyoxymethylene resin having a branched structure as a nucleating agent. Furthermore, Japanese Patent Publication No. 48-8254 describes the addition of an inorganic compound typified by talc as a nucleating agent.

[0006]

[Problems to be Solved by the Invention] However, the above-mentioned Japanese Patent Application Laid-Open No. 129247/1982 and Japanese Patent Publication No. 55-1994
The resin compositions described in Publication No. 2 and Japanese Patent Publication No. 48-8254 do not improve the crystallization rate sufficiently, and not only cannot a satisfactory high cycle performance be expected, but also the crystallization of the obtained molded product is Improvement in mechanical strength by making the structure finer and more homogeneous is also insufficient, and does not satisfy the higher mechanical strength required for applications such as electrical and electronic equipment products and automobile parts.

[0007]

[Means for Solving the Problems] The present inventors have conducted intensive studies to obtain a polyoxymethylene resin having excellent high cycle properties and mechanical properties without adding a nucleating agent, and as a result, they have arrived at the present invention.

That is, the present invention provides (a) trioxane and (b)
) ethylene oxide, 1,3-dioxolane, 1,3-
Dioxepane, 1,3,5-trioxepane, 1,3,
An oxymethylene multicomponent copolymer obtained by copolymerizing at least one cyclic ether compound selected from 6-trioxocane and (c) at least one compound selected from glycidyl phenyl ether, styrene oxide, and glycidyl naphthyl ether. The melting point (Tm) and cooling crystallization temperature (Tc) of the oxymethylene multi-component copolymer are
The present invention provides an oxymethylene multi-component copolymer, which has the following relationship: 15≦Tm-Tc<25 (°C), and has a spherulite size of 30 μm or less.

The method for producing the oxymethylene multi-component copolymer of the present invention is not particularly limited. For example, at least one member selected from trioxane as the component (a) and ethylene oxide, 1,3-dioxolane, 1,3-dioxepane, 1,3,5-trioxepane, and 1,3,6-trioxocane as the component (b). A cyclic ether compound and at least one compound selected from glycidyl phenyl ether, styrene oxide, and glycidyl naphthyl ether as component (c) are dissolved or suspended in an organic solvent such as cyclohexane, and then a Lewis acid catalyst is added. It can be produced by polymerizing and decomposing and removing unstable ends. Preferably, there is a method of producing by bulk polymerizing using a self-cleaning stirrer without using any solvent, deactivating the catalyst with a hindered amine compound, and then decomposing and removing unstable terminals. As a Lewis acid catalyst, boron trifluoride,
Boron trifluoride hydrate and coordination compounds of boron trifluoride and organic compounds having oxygen or sulfur atoms are preferably used. The amount of Lewis acid catalyst added is preferably in the range of 0.001 to 0.1 part by weight, particularly preferably in the range of 0.005 to 0.05 part by weight, per 100 parts by weight of trioxane. Moreover, the bulk polymerization reaction temperature is 60 to 12
A temperature range of 0°C is preferred, and a range of 60 to 90°C is particularly preferred. What is a hindered amine compound that deactivates a catalyst?
Bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl-1-(2-hydroxyethyl succinate) -2,2,6,6 tetramethylpiperidine polycondensate, 1-[2-[3-(3,5
-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-(3.5-di-t-
It refers to a compound having a hindered amine skeleton in the molecule, such as butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, and the amount added is per boron atom of the catalyst. It is preferable to add the amount corresponding to 0.1 to 20 nitrogen atoms in the hindered amine compound.

[0010] Component (b) in the oxymethylene multi-component copolymer of the present invention is selected from ethylene oxide, 1,3-dioxolane, 1,3-dioxepane, 1,3,5-trioxepane, and 1,3,6-trioxocane. The copolymerization amount of at least one cyclic ether compound is important in order to obtain sufficiently high mechanical strength. For the unit, 0.
It is preferably in the range of 0.01 to 2.0 mol%. 0.
If it is less than 0.01 mol%, the thermal stability will decrease, and if it exceeds 2.0 mol%, it will be difficult to obtain a polymer with sufficiently excellent mechanical strength, which is not preferred.

[0011] In the oxymethylene multi-component copolymer of the present invention, the copolymerized amount of at least one compound selected from glycidyl phenyl ether, styrene oxide, glycidyl naphthyl ether as component (c) is greater than the amount of trioxane, etc. as component (a). 0.0 for the oxymethylene unit derived from
It is preferably in the range of 0.001 to 2.0 mol%, particularly preferably in the range of 0.01 to 1.0 mol%. If it is less than 0.001 mol%, the effect of improving high cycle performance is small, and if it exceeds 2.0 mol%, mechanical strength will decrease, which is not preferable.

The degree of polymerization of the oxymethylene multi-component copolymer of the present invention is determined according to ASTM D1238 using pellets dried in a hot air oven at 80°C for 3 hours.
MI value measured at 90℃ and a load of 2160g, 1 to 60
Preferably, it is in the range of g/10 minutes. The number average molecular weight is preferably in the range of approximately 8,000 to 100,000. If the MI value is less than 1 g/10 min, the fluidity during injection molding will decrease, making it impossible to mold a thin-walled molded product, which is not preferable. Moreover, if it exceeds 60 g/10 minutes, the degree of polymerization will be low and mechanical strength will become a problem, which is not preferable.

The oxymethylene multi-component copolymer of the present invention has
In order to have excellent high-cycle moldability and mechanical properties, the relationship between the melting point (Tm) and cooling crystallization temperature (Tc) of the oxymethylene multi-component copolymer is 15≦Tm-Tc<25 (°C), In addition, it is necessary that the spherulite size be 30 μm or less. If Tm-Tc is less than 15°C due to low Tm, it is difficult to obtain sufficiently high mechanical strength;
If Tm-Tc is 25° C. or higher due to high Tm-Tc, the inherent thermal stability of the oxymethylene copolymer will be impaired, which is not preferable. Furthermore, if Tm-Tc is less than 15°C due to high Tc, the toughness will be greatly reduced, and conversely, if Tm-Tc is 25°C or more due to low Tc, residual strain after injection molding will occur. is undesirable because it is large and reduces mechanical strength. That is, in order to obtain a sufficiently high mechanical strength, the amount of copolymerization of component (b) must be below a certain level, which increases Tm, but on the other hand,
In order to obtain excellent high cycle performance and high mechanical strength (
When component c) is copolymerized, Tc increases. Furthermore, if the spherulite size is 30 μm or more, residual molding distortion after injection molding is large and mechanical properties are deteriorated, which is not preferable.

[0014] In the present invention, Tm and Tc are measured using a differential scanning calorimeter (DSC) under a nitrogen atmosphere at room temperature.
Raise the temperature to 220°C at a rate of 0°C/min and leave at 220°C for 5 minutes.
After holding the temperature at
A method was adopted in which the temperature was raised at a rate of 0° C./min and the melting point (Tm) was measured. The Tm of the oxymethylene multi-component copolymer of the present invention is preferably in the range of 155 to 180°C,
Particularly preferably, the temperature is in the range of 160 to 175°C. Tc of the oxymethylene multi-component copolymer of the present invention is 140 to 155
It is preferably in the range of 145 °C, particularly preferably 145 °C.
-152°C.

[0015] The spherulite size was determined by sandwiching about 2 mg of the oxymethylene multi-component copolymer between cover glasses, heating it on a hot stage, melting it at 230°C for 5 minutes, and then melting it at 10°C while observing it with a polarizing microscope. A method was adopted in which the temperature was lowered to 130°C at a rate of 1/min, and the spherulite size was determined by photographing the formed crystals.

In addition, the oxymethylene multi-component copolymer of the present invention may contain known antioxidants such as hindered phenol, phosphite, thioether, and amine antioxidants, and benzophenone, within a range that does not impair the purpose of the present invention. Weathering agents such as melamine, hindered amine, formaldehyde scavengers such as melamine, dicyandiamide, polyamide, and polyvinyl alcohol copolymers, antifriction agents such as fluorine-containing polymers, silicone oil, and polyethylene wax, coloring agents such as dyes and pigments, UV shielding agents such as titanium oxide and carbon black, reinforcing agents such as glass fiber and carbon fiber titanate potassium fiber, silica, clay,
Fillers such as calcium carbonate, calcium sulfate, and glass beads, nucleating agents such as talc, flame retardants, plasticizers, adhesion aids, adhesives, and the like can be optionally contained. Furthermore, for the purpose of improving the mechanical strength of the oxymethylene multi-component copolymer of the present invention, other thermoplastic polymers or thermoplastic elastomers may be contained.

[0017]

[Example] The effects of the present invention will be explained below with reference to Examples.

Note that all percentages and parts in the examples are based on weight. In addition, the molding cycle, mechanical properties, etc. were measured as follows.

- Molding cycle: Using an injection molding machine with an injection capacity of 5 ounces, the cylinder temperature was set to 190°C, the mold temperature was 60°C, and the injection time was 5 seconds.The cooling time was changed to 80×80× When a 3mmt square plate is molded and the three vertices of the molded product are placed on the flat plate due to deformation using four ejector pins, the deviation of the remaining one vertex from the flat plate is 1mm.
The following cooling times were measured.

- Mechanical properties: ASTM No. 1 dumbbell test piece was injection molded using an injection molding machine with a 5 oz injection capacity, setting the cylinder temperature to 190°C, the mold temperature to 65°C, and the molding cycle to 50 seconds. . Using the obtained ASTM No. 1 dumbbell test piece, tensile strength was measured according to ASTM D638 method, and flexural modulus was measured according to ASTM D790 method.

Examples 1 to 5, Comparative Examples 1 to 5100mmφ
, 2-shaft continuous mixer with L/D=10 (manufactured by Kurimoto Iron Works)
Trioxane, the compound of component (b), the compound of component (c), and 100 ppm boron trifluoride diethyl etherate (2.5% benzene solution) with respect to trioxane were added to KRC kneader "S-4 type), and the degree of polymerization was Continuous polymerization was carried out by supplying each of the regulators, methylal. The polymerization temperature was controlled at approximately 60°C by passing hot water through the outer jacket, and the rotation speed was set at 60 rpm. (c
) component compound and methylal as a molecular weight regulator,
Dissolved in trioxane. Further, a premixing zone was provided so that the compound of component (b) and the catalyst solution were premixed immediately before being supplied to the kneader. The polymer was obtained as a white fine powder.

A solution of 27 g of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate dissolved in 200 ml of benzene was added to 10 kg of the fine powder thus obtained. After deactivating the catalyst, 10 g of calcium stearate, 1,6-hexanediol-bis-[3-(3,5-di-t-butyl-4-
Hydroxyphenyl) propionate] [Irganox (I) manufactured by Ciba-Geigy
rganox)” 245] was added and stirred for 10 minutes in a Henschel mixer.
Using a vented twin-screw extruder with mmφ and L/D=30, the cylinder temperature was 230°C and the vent vacuum degree was 5 Torr.
After melt stabilization under these conditions, the mixture was discharged into water and cut to obtain a pellet-like oxymethylene multi-component copolymer. The composition of the obtained oxymethylene multi-component copolymer was confirmed by 60 MHz 1H NMR (in heavy hexafluoroisopropanol solvent). For example, (c)
When glycidylphenyl ether is used as a component compound, in addition to the methylene group signal at δ4.3-5.2 (ppm), there is a multiplet signal unique to phenyl groups at δ6.9-7.6 (ppm). By the detection, it was confirmed that it was a glycidyl phenyl ether copolymer. Also. It was confirmed by the integral value that the copolymerization was almost quantitative based on the amount charged. Table 1 shows the copolymer composition and physical properties of the various oxymethylene multi-component copolymers thus obtained.

[0023]

[Table 1]

From the results shown in Table 1, it is clear that the multi-component copolymer of the present invention has excellent injection moldability and mechanical properties.

[0025]

Effects of the Invention The oxymethylene multi-component copolymer of the present invention provides a polyoxymethylene resin molded article having a small spherulite size, low molding distortion, and high mechanical properties.

Claims (1)

[Claims] Claim 1: (a) trioxane and (b) at least one member selected from ethylene oxide, 1,3-dioxolane, 1,3-dioxepane, 1,3,5-trioxepane, and 1,3,6-trioxocane. An oxymethylene multi-component copolymer obtained by copolymerizing a cyclic ether compound and (c) at least one compound selected from glycidyl phenyl ether, styrene oxide, and glycidyl naphthyl ether, the oxymethylene multi-component copolymer An oxymethylene multicomponent compound characterized in that the relationship between the melting point (Tm) and cooling crystallization temperature (Tc) is 15≦Tm-Tc<25 (°C) and the spherulite size is 30 μm or less. Polymer.