JPS6026054A - Saponified ethylene/vinyl acetate compolymer composition for molding - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which gives moldings having good surface smoothness and appearance and can be molded into small thin-wall parts, by blending a potassium titanate fiber with a saponified ethylene/vinyl acetate copolymer. CONSTITUTION:The titled compsn. is obtd. by blending 50-5wt% potassium titanate fiber (A) with 50-95wt% saponified ethylene/vinyl acetate copolymer (B) which has an ethylene content of 10-55mol% and whose vinyl acetate moiety has a degree of saponification of 90mol% or above. A conventional composition comprising the polymer B contg. glass fiber blended therewith gives moldings which have disadvantages in that, since glass fibers come out to the surface of the moldings, the surface smoothness is poor and the resin itself is slightly yellowish so that the appearance is marred. Further, the glass fiber is so large that the molding can be hardly thin-walled or small-sized. By blending the fiber A, the compsn. can give moldings having good appearance, high whiteness degree, good surface smoothness as well as high mechanical strength, though the fiber length is short. Further, the compsn. can be molded into small thin-walled articles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding composition based on a saponified ethylene-vinyl acetate copolymer.

Saponified ethylene-vinyl acetate polymer has good mechanical strength, non-static properties, oil/solvent resistance, and abrasion resistance, so it is gradually being put into practical use in fields such as mechanical parts and structural parts. It is becoming more and more popular. In particular, the molded product obtained by blending glass fiber with the resin has further improved mechanical properties such as tensile strength, tensile modulus, flexural strength, flexural modulus, and compressive strength. 25~ fiber
Those with a composition of 55% (silver content, the same applies hereinafter) are commercially available as molding materials and are mainly used.

However, molded products of saponified ethylene-acid-resistant vinyl copolymer blended with such glass fibers have poor surface smoothness because the glass fibers appear on the surface of the molded product, and the resin itself has a slight yellow color. Because it has a taste, it has the disadvantage of detracting from its appearance.

, 1: The mechanical strength and elastic modulus are good (but the size of the glass filament is 3 to 13 mm in average fiber diameter, 3 to 13 mm in average fiber length).
Due to the large Ili value of 1 or more, there is a limit to the thinning, miniaturization, and miniaturization of molded products, which has been a major barrier to application to small parts such as precision machinery, office equipment, and home appliances.

In view of the above-mentioned circumstances, the present inventors have conducted extensive research and have found that an ethylene-vinyl 11-acid copolymer with an ethyl-1-one content of 10 to 55 mol% and a degree of saponification of the vinyl acetate moiety of 90 mol% or more has been prepared. A saponified ethylene-vinyl acetate copolymer molding composition characterized by containing 50 to 95% of titanate and 50 to 5% of potassium titanate fiber has extremely good surface smoothness and is white in color. Despite the short fiber length of potassium titanate fibers, the mechanical strength, especially the elastic modulus, is higher than that of conventional glass fiber reinforced products.
In addition, it is possible to provide a molded product with an extremely beautiful appearance. Combined with the micro-filling property that takes advantage of the small size of the fibers involved, it is possible to achieve the molded part's excellent quality (11-), and the orientation of the fibers. However, conventional) F lath MLF is smaller than carbon fiber and has 4 superior precision moldability, and mold installation! 11 is easy゛τ・
We have found six ways to solve the above-mentioned problems and have completed the present invention.

Saponified tyrene-vinyl acetate copolymer used in the present invention 1.1, Brene content 10-55%, 1
itti1! The composition has a saponification degree of 90 moles or more of 96 or more in the vinyl moiety. Ethylene barge is 55 mol%
If it exceeds 10% by mole, the heat deformation temperature of the molded product will decrease, while if it is less than 10% by mole, the melting point of the resin and the thermal decomposition temperature will become close to each other, making molding difficult, which is not preferable. Among these, moldability,
In view of the balance of various performances such as mechanical properties and heat distortion temperature, the molding composition of the present invention has a T tyrene-containing mackerel of 25 to 4
A range of 5 mol % has been found to be suitable.

In addition, if the degree of saponification is less than 90 mol%, thermal stability, heat distortion temperature J2, and mechanical properties will decrease significantly, which is undesirable. Desirably, the degree of saponification of 3 parts of vinyl acetate is 95 mol% or more.

In addition to ethylene and vinyl acetate (or saponified vinyl alcohol), monomer components that can be copolymerized with them, such as olefins such as propylene and isobutylene, acrylic acid, methacrylic acid, maleic acid, and chlorol- Even if it contains a small amount of unsaturated acid such as phosphoric acid or its ester, it can be applied to the present invention.

The potassium titanate fiber used in the present invention means a single crystal fiber represented by the general formula: % formula % (where n represents an integer of 2 to 8), and specifically, for example, 4 Potassium titanate fiber, potassium hexatitanate fiber 1 or potassium octitanate fiber, etc. alone or a mixture thereof,
The average fiber diameter is 2 or less, the average fiber length is 5 to 100 nights,
And 5-4- Average m fiber/average II navy diameter (asparagus I/ratio) is 10~
200 is preferred.

Potassium titanate &&! Navy average fiber H
Stirring and average IIi Yorinaga are respectively scanned electron microscopy Wi
It is the average value of the values measured for at least 10 or more fibers per field of view for at least 5 or more fields of view using a mirror, and the aspect ratio is the average long fiber long fiber diameter of the fiber. It refers to the divided value.

Average fiber diameter of potassium titanate fiber, average fiber length 8')
If the rib aspect ratio is outside the above range, for example, if the average II fiber diameter is less than 1ρ and the average S&l1lt length is less than 5ρ, that is, if the aspect ratio is less than 10, the molded product is strengthened. This is not preferable because the effect is small. Further, long fiber cloth having an average fiber length of 100 mm or more is difficult to manufacture industrially and is of little practical use.

A suitable blending layer of potassium titanate fiber 1 is 5 to 50%; if it is less than 5%, the reinforcing effect will be poor, while if it exceeds 50%, the melt viscosity will become too high, causing problems in G-formability. I also don't like it.

This section describes the use of potassium titanate fibers, saponified ethylene-vinyl acetate copolymers, silane coupling agents, ditanate coupling agents, epoxy resins, and epoxy urethane resins for the purpose of improving the adhesive properties of saponified ethylene-vinyl acetate copolymers. In addition to surface-treated materials such as
■A method of adding a silane coupling agent, etc. when producing a molding composition (pellet) by mixing and extruding a saponified tyrene-'fl# acid vinyl copolymer and potassium titanate fibers that have not been surface treated. However, it can be used effectively.

Various methods can be used to produce the molding composition of the present invention, including (1) a method in which potassium titanate fibers are blended from the beginning of polymerizing monomers such as ethylene and vinyl acetate; (2) (3) A method of blending potassium titanate fibers during polymerization or saponification;
It is possible to apply a method such as kneading and extruding the ditanic acid nitrate fiber using extrusion II or the like, and then cooling it with water and turning it into a beret. ) method is the most practical.

In addition, the molding composition of the present invention may contain H fuel agents, heat stabilizers, violet IA ray absorbers, quenchers, etc., depending on the purpose, within a range that does not interfere with the improved effects of the present invention. Add additives C'
l:) J.i..

The molding composition of the present invention has a fiber size of 1/10 to 1/10 compared to conventional glass fiber or carbon reinforced crystal.
1/100 microscopic potassium titanate w4Ill
Since G! is used as a reinforcing material, it is possible to mold very small and thin parts, and it also eliminates the embossed fibers seen in conventional glass fiber reinforced products. In addition, the mechanical strength of the molded product is comparable to that of conventional glass fiber reinforced parts. It has high strength, especially in terms of elastic modulus, because potassium titanate is a single crystal fiber, it has higher elasticity than glass fiber reinforced products, and it allows for lighter, thinner and smaller molded products. Its practical 1i11i value is extremely large and useful.

Hereinafter, the present invention will be explained in detail based on examples.
However, the present invention is not limited to such embodiments.

Implementation @ 1 to 4 and Comparative Examples 1 to 2 Contains ethylene! saponified ethylene-vinyl acetate copolymer with a saponification degree of 127 mol% and a saponification degree of the vinyl acetate portion of 99.0 mol%;
Potassium titanate fibers with an average fiber length of 15 strands or alkali-free glass fibers with an average fiber diameter of 13 strands and a cut size of 31 nIIl for comparison (chopped strands with a filament count of 400, surface treated with a vinyl silane treatment agent) ) and molding compositions blended as shown in Table 1 were charged into a 45 m/w + single-screw extruder and
By melt-kneading at a temperature of −9−−8−° C. for 1 J, the mixture was converted into a powder.

Next, the injection temperature was 240°C, and the mold 1 [
The following test pieces were prepared by injection molding at 80°C and an injection rE force of 1000 kv/-, and their physical properties were evaluated using the methods shown below. Summary of the results
Holo on the front.

Bending strength J, bending bullet 1'l rate: length 185±1u+
Using five test pieces each having a width of 10±0.5-1 and a height of 4±0.2-1, measurements were made under conditions of a distance between fulcrums of 6011 and a turning head speed of 5 mm/min.

Mold shrinkage rate, Hunter white t1t and surface flatness: Length 6011 m, Width 50 Ugly - 1 Height 3 - Seaweed Idugu 1
- For three flat plates, the molding shrinkage rate was determined using a micrometer, Hunter white discoloration was determined using colorimetric color difference IT, and surface smoothness was determined using the naked eye.

-10-・-11- It is clear from Table 1 that the effects on the bending strength and bending modulus of sea urchin and potassium ditanate fibers are extremely large.
It is superior to glass fibers with a large fiber size of 114J, and has a remarkable effect of improving the elastic modulus. It can also be seen that the anisotropy of the molding shrinkage rate is small and the surface with large Hunter white discoloration gives a very flat and beautiful molded product.

Examples 5 to 7 and Comparative Examples 3 to 4 As shown in Table 2, saponified ethylene-vinyl acetate copolymers having different ethylene contents and degrees of chlorination of the vinyl acetate moiety were used to prepare Example 1. Pe1-no-1-, which contains 30% of the same Norium titanate fiber used in ~4.
were prepared in the same manner as in Examples 1 to 4. 1. Bending strength, bending elastic modulus, and Hunter white discoloration were measured in the same manner as in Examples 1 to 4. The binding is summarized in Table 2.

From the results in Table 2, it can be seen that the mechanical properties tend to decrease as the ethylene content increases, and the ethylene content is 10 to 55 mol%, preferably 25 to 45 mol%, and The degree of saponification of the part can be determined to be 90 mol% or more, preferably 95 mol% or more from the viewpoint of mechanical properties and thermal stability (Hunter white discoloration).

Claims (1)

[Scope of Claims] 1. 50 to 95% by weight of a saponified ethylene-vinyl acetate copolymer containing 110 to 55 mol% of ethylene, a degree of saponification of the vinyl acetate portion of 90 mol% or more, and 50 to 95% by weight of potassium titanate fibers. A saponified ethylene-vinyl acetate copolymer molding composition, characterized in that it is blended in a proportion of 5%. 2 A saponified ethylene-vinyl acetate copolymer having an ethylene content of 25 to 45 mol% and a degree of saponification of the vinyl acetate portion of 95'Ele% or more is used, and the potassium titanate fiber has an average fiber N diameter of 2 prints. The composition according to claim 1, wherein the composition has an average mH length of 5 to 100, and an average fiber length/average line #ti diameter of 10 to 200. 1-