JPH0788451B2 - Molding resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition for molding containing a saponified ethylene-vinyl acetate copolymer and glass fiber as main components.

2. Description of the Related Art A molded product obtained by blending glass fiber with a saponified product of ethylene-vinyl acetate copolymer and melt-molding has mechanical strength,
Since it has extremely high rigidity and excellent oil resistance and solvent resistance, it is useful as an engineering plastic.

When the glass fiber is mixed with the saponified ethylene-vinyl acetate copolymer and molded, a colorant is often mixed in order to improve the appearance of the molded product. There are advantages like.

(A) A white molded product obtained by blending a white colorant alone is in great demand in terms of quantity.

(B) When the white colorant is used in combination with another colorant, the latter coloration becomes clear.

(C) A molded product obtained by blending a large amount of glass fiber with a saponified product of ethylene-vinyl acetate copolymer may have a rough surface or flow marks on the surface. It is often painted, but if the ground color is white, beautiful painting is possible.

Conventionally, titanium oxide, which has excellent hiding power even with a small amount of compound, has been used exclusively as a white colorant when compounding glass fibers with a saponified ethylene-vinyl acetate copolymer and molding the mixture. It should be noted that calcium carbonate, talc, etc. are white powders because of their diffuse reflection, but it is more accurate that they are colorless in the state of being mixed with a resin and molded, and they are useful as extender pigments, but as white colorants. Not very suitable.

Although it does not relate to a saponified ethylene-vinyl acetate copolymer, JP-B-46-15024 discloses a molding material in which a phthalocyanine pigment is added to polyethylene terephthalate in which glass fiber or glass powder is added, and the publication discloses that. Shows a comparative example in which titanium oxide, calcium carbonate, clay or the like is mixed as a pigment, and an example in which a phthalocyanine pigment is used in combination with titanium oxide.

Similarly, it does not relate to a saponified ethylene-vinyl acetate copolymer, but it is disclosed in JP-B-55-24466 (JP-A-49-570).
No. 44), for polyamide or polybutylene terephthalate reinforced with glass fiber, the use of zinc sulfide as a white colorant causes less reduction in mechanical strength than the use of titanium oxide. It is shown.

Problems to be Solved by the Invention In general, when glass fiber is blended with a saponified ethylene-vinyl acetate copolymer and subjected to melt molding, the flow of the melt deteriorates and molding cannot be performed smoothly. There is. Especially when the proportion of glass fiber to be mixed increases,
The moldability is significantly reduced.

When titanium oxide as a white colorant is blended with a system consisting of this saponified ethylene-vinyl acetate copolymer and glass fiber, the melt moldability is further lowered even when a small amount of about 1% by weight or less is blended. There is a problem that the surface condition of the molded product to be deteriorated becomes poor and the mechanical properties are significantly deteriorated.

Since such a problem impairs the advantage of the system in which the saponified ethylene-vinyl acetate copolymer is mixed with the glass fiber, its solution is strongly desired.

INDUSTRIAL APPLICABILITY The present invention prevents deterioration of moldability that occurs when a glass fiber and a white colorant are added to a saponified ethylene-vinyl acetate copolymer and subjected to melt molding, and the surface condition of the obtained molded product is deteriorated. It is an object of the present invention to provide a molding resin composition capable of preventing the above-mentioned problems and further suppressing a decrease in mechanical strength.

MEANS FOR SOLVING PROBLEMS The molding resin composition of the present invention comprises a saponified ethylene-vinyl acetate copolymer (A having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl acetate component of 90 mol% or more). ) Is mixed with glass fiber (B) and zinc sulfide (C), and the proportion of glass fiber (B) in the total amount of saponified ethylene-vinyl acetate copolymer (A) and glass fiber (B). Is 10 ~
70% by weight, and the blending amount of zinc sulfide (C) is 0.01 to 3% by weight with respect to the total amount of the saponified ethylene-vinyl acetate copolymer (A) and the glass fiber (B). By finding such a specific combination, the above object has been achieved.

The present invention will be described in detail below.

In the present invention, as the ethylene-vinyl acetate copolymer saponified product (A), a composition having an ethylene content of 20 to 60 mol% and a saponification degree of the vinyl acetate component of 90 mol% or more, preferably an ethylene content of 25 Use a composition of ˜55 mol% and a saponification degree of vinyl acetate component of 97 mol% or more. When the ethylene content is less than 20 mol%, the melt moldability is poor and the molding itself becomes difficult. On the other hand, when the ethylene content exceeds 60 mol%, the rigidity, oil resistance and solvent resistance of the obtained molded product deteriorate. If the degree of saponification of the vinyl acetate component is less than 90 mol%, the mechanical strength, rigidity, oil resistance and solvent resistance of the obtained molded article will deteriorate.

As the glass fiber (B), commercially available glass fiber chopped strand, glass roving, or the like is used. Chopped strands are particularly preferable.

As zinc sulfide (C), any commercially available zinc sulfide pigment is used.

The mixing ratio of each component is determined as follows.

The proportion of the glass fiber (B) in the total amount of the saponified ethylene-vinyl acetate copolymer (A) and the glass fiber (B) is
Set to 10 to 70% by weight. If the proportion of the glass fibers (B) is less than this range, the desired mechanical strength and rigidity cannot be obtained, while if the proportion of the glass fibers (B) is greater than this range, the moldability becomes extremely poor. A particularly preferred range is 20
~ 65% by weight.

The blending amount of zinc sulfide (C) is based on the total amount of the saponified ethylene-vinyl acetate copolymer (A) and the glass fiber (B).
It is selected from the range of 0.01 to 3% by weight. When the content of zinc sulfide (C) is less than 0.01% by weight, white coloring and the effect of improving moldability are not sufficiently exhibited, while when the content of zinc sulfide (C) exceeds 3% by weight, whiteness Does not exceed a certain limit and tends to reduce moldability. A particularly preferred range is 0.05 to 2.5% by weight.

As described above, the composition of the present invention contains three components of the saponified ethylene-vinyl acetate copolymer (A), the glass fiber (B) and the zinc sulfide (C) as essential components.
Other thermoplastic resins (polyamide, polyester, polyolefin, etc.), fibers other than glass fibers (whiskers, carbon fibers, etc.), coloring agents or fillers other than zinc sulfide (various dyes, mineral pigments, extender pigments, etc.), stable Agents, lubricants, plasticizers, flame retardants, antistatic agents and the like may be added.

The respective components are mixed simultaneously or in any order and then subjected to melt molding. At this time, for example, glass fiber (B) and zinc sulfide (C) were mixed in advance with the saponified product of ethylene-vinyl acetate copolymer (A) to prepare a masterbatch, which was prepared in advance as an ethylene-vinyl acetate copolymer. It is also possible to adjust the final composition by blending with the saponified product (A).

As the melt molding method, an injection molding method, an extrusion molding method, a compression molding method, or the like is adopted. The molding temperature varies depending on the composition of the saponified product of ethylene-vinyl acetate copolymer (A), but a temperature condition of about 180 to 250 ° C. is adopted.

After the molded product is obtained, its surface can be coated for makeup if necessary.

Action In the present invention, zinc sulfide (C) has a role of imparting white color to the molded product, but in addition to that, it has a function of smoothing the flow of the molten material at the time of molding, so that suppression of thickening with time at the time of molding is suppressed. Contributes to maintaining the surface smoothness of the molded product.

Since zinc sulfide (C) has a small surface tension, it has excellent compatibility with other coloring agents. When zinc sulfide (C) is used in combination with other coloring agents, the resulting molded product is colored vividly. It also shows the effect.

The weather resistance of zinc sulfide (C) is said to be excellent unless the three elements of oxygen, water and ultraviolet light are aligned, but in the composition of the present invention, the saponified ethylene-vinyl acetate copolymer (A 2) has an extremely excellent oxygen barrier property, the compounded zinc sulfide (C) does not cause any trouble in terms of weather resistance.

The effect of improving the moldability by the zinc sulfide (C) is specifically obtained when the saponified ethylene-vinyl acetate copolymer (A) is used as the resin component, and other thermoplastic resins such as polyester and polyamide are used. When used, even if zinc sulfide (C) is blended, notable effect of improving formability is not exhibited.

EXAMPLES Next, the present invention will be further described with reference to examples. Hereinafter, “parts” means parts by weight.

Preparation of molding material The following molding material was prepared.

-Resin component- (A): Saponified ethylene-vinyl acetate copolymer having ethylene content of 29 mol% and saponification degree of vinyl acetate component of 99.8 mol% (GL-M manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (A1) : Polybutylene terephthalate (Mitsubishi Rayon Co., Ltd., N-1000) (A2): Polyethylene terephthalate (Nippon Unipet Co., RN163M) (A3): Nylon 66 (Ube Industries 2020B) -Glass fiber- ( B): Glass fiber (chopped strand of fiber diameter 13 μm, fiber length 3.6 mm) -Colorant- (C): Zinc sulfide (West Germany, Sactolven, Sactris HD-S, particle size 0.3 μm) (C1): Titanium White (titanium oxide) -based pigment (C2): Titanium white (titanium oxide) (chlorine method rutile, particle size 0.6 μm, Al treatment) (C3): Phthalocyanine blue (West Germany, Badish Aniline Co., Ltd.) Chose composition the proportions of the components as in Table 1 below.

Preparation of Molding Pellets According to the above composition, each component was first mixed with a tumbler, then supplied to an extruder, extruded in a strand shape, and pelletized.

Measurement of Melt Viscosity and Measurement Results Of the above-mentioned molding pellets, the compounding compositions of Reference Example 1, Example 1, Comparative Example 1, Comparative Example 2, Example 2 and Comparative Example 3 were melted under the following conditions. The viscosity was measured.

Table 2 shows the results of using a Koka type flow tester, load 50 kg, temperature 250 ° C, nozzle diameter 1 mmφ.

It can be seen from Table 2 that when titanium oxide is used as the white colorant (Comparative Examples 1 to 3), the melt viscosity is higher than that of the blank (Reference Example 1) and the thickening phenomenon over time is large.

On the other hand, when zinc sulfide was used as the white colorant, a blank (Reference Example 1) was obtained in a 0.3 part formulation (Example 1).
In comparison with the blank (Reference Example 1), there is a tendency to be equal or more advantageous in terms of melt viscosity and increase in viscosity over time, and in 1.0 part formulation (Example 2), in terms of melt viscosity and increase in viscosity over time. It turns out to be advantageous.

Preparation of test piece, test condition Among the above-mentioned molding pellets, Reference Example 1, Example 1, Comparative Example 1, Comparative Example 2, Example 2, Example 3 and Comparative Example 3
The molding pellets obtained with the compounding composition of are supplied to the injection molding machine, the cylinder maximum temperature is 250 ° C, the mold temperature is 60 ° C, and the injection pressure is 1
The following three types of test pieces were prepared by injection molding under the condition of 000 kg / cm ² , and the mechanical properties were measured under the following conditions.

Test piece For tensile test Type-I test piece according to ASTM D638 For bending test ASTM D790 thickness 6.4 mm, width 12.7 mm, length 127 mm test piece For impact test ASTM D256 thickness 12.7 mm, width 12.7 mm,
63.5 mm long test piece, notch with notch is V notch, depth is 2.54 mm Test condition Tensile test Shimadzu Corporation Autograph AG-5000A
Used, used load cell 5000 kg, distance between knobs 115 mm,
Tensile speed 5mm / min Bending test Shimadzu Corporation Autograph AG-5000A
Used, used load cell 500kg, fulcrum span 101.6mm, bending speed 2.5mm / min Impact test Izod impact tester used, weighing 40kg-cm,
Hammer lifting angle 150 ° Measurement results Tables 3 and 4 show the results of external observation of the test pieces and the results of measuring the mechanical properties of the test pieces.

From Tables 3 and 4, the surface conditions of the test pieces obtained by molding tend to be lower than those of the blanks (Reference Example 1) in the comparative examples, but in the case of the examples. It can be seen that in both cases, the surface condition is better than that of the blank (Reference Example 1).

Further, from Tables 3 and 4, it can be seen that the mechanical properties of the test pieces obtained by molding tend to be significantly reduced in all cases of Comparative Examples as compared with the blank (Reference Example 1). In all cases, the decrease is smaller than that of the blank (Reference Example 1), and it may be understood that the bending strength and the notched impact strength may not be decreased at all.

When Other Resins are Used Among the molding pellets, the pellets of Reference Example 2 and Comparative Example 4, Reference Example 3 and Comparative Example 5, and Reference Example 4 and Comparative Example 5 are supplied to an injection molding machine to have a thickness of 3.2 mm, A disk with a diameter of 100 mm was obtained, and the surface condition was observed. In each comparative example, the surface was smoother than that of the blank (each reference example) even though zinc sulfide (C) was blended. The property did not change, and the effect of improving the moldability by the compounding of zinc sulfide as seen in the relationship between each of the above Examples and Reference Example 1 was not recognized.

EFFECT OF THE INVENTION The molding resin composition of the present invention is capable of continuous molding for a long time because the flow of the melt becomes smooth even when a large amount of glass fiber is blended, and viscosity increase with time is suppressed. The obtained molded product has good surface smoothness.

In addition, in the present invention, since the decrease in mechanical strength is small even though the white colorant is blended, the saponified ethylene-vinyl acetate copolymer (A) is added to the glass fiber (B). The excellent mechanical strength, which is an advantage of the compounded system, is hardly impaired.

Since zinc sulfide (C) is a white colorant, when it is used alone, a white molded product with a large demand is obtained, and when the white molded product is painted, the ground color is white. Therefore, clear painting is possible. On the other hand, even if it is used in combination with another dye-based or pigment-based coloring agent, the compatibility is good, so that the coloring by the other coloring agent becomes clear. The presence of the saponified ethylene-vinyl acetate copolymer (A) helps maintain the weather resistance of zinc sulfide (C), and does not cause discoloration even when the molded product is used outdoors.

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Claims (1)

[Claims] 1. An ethylene-vinyl acetate copolymer saponification product (A) having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl acetate component of 90 mol% or more is added to a glass fiber (B) and a zinc sulfide (C). ) Are blended, the proportion of the glass fiber (B) in the total amount of the saponified product of ethylene-vinyl acetate copolymer (A) and the glass fiber (B) is 10 to 70% by weight, and ethylene-vinyl acetate The blending amount of zinc sulfide (C) is 0.01 with respect to the total amount of saponified copolymer (A) and glass fiber (B).
A resin composition for molding which is ˜3% by weight.