JPS591742B2 - Easily incinerated polypropylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an easily inflammable polypropylene resin composition that is made of polypropylene and calcium carbonate and has excellent injection moldability.

More specifically, even for molded products with complex mold structures, such as glass pin stoppers and molded products with precise lattices, the molded product can be easily released from the mold, and it is also easy to release the molded product from the mold during molding. The present invention relates to an easily inflammable polypropylene resin composition which has excellent injection moldability and can produce molded products with good molding efficiency and good appearance with low internal stress due to its excellent fluidity. The development of the plastic industry has been remarkable in recent years, and due to the excellent mechanical and electrical properties of synthetic resins, as well as the ease of moldability, synthetic resins have become widely consumed in large quantities in various industrial fields. It has become an important basic industrial material indispensable to people's lives. However, on the other hand, due to its properties, plastics do not decompose in natural ecosystems, retain their initial shape for many years, and are not returned to the natural world. For this reason, once discarded plastic has become a social problem as waste pollution. In addition, a considerable amount of plastic waste is included in municipal garbage, and when it is incinerated at municipal waste disposal plants,
A large amount of black smoke is generated, and the amount of combustion heat is greater than that of cellulosic materials such as main wood and paper, so the furnace is damaged quickly, and combined with melt dripping during combustion, the combustion process is significantly delayed. This has made it difficult to do so, and the problem of secondary pollution has also arisen. For this reason, methods have been proposed to improve incineration properties, such as adding inorganic fillers such as calcium carbonate to polyolefins to reduce burned calories and prevent melt dripping. This leads to the conservation of oil resources, and is also a desirable method as a low-pollution technology.

There are a number of inorganic fillers that are useful for this purpose, but the practical ones include carbonates (e.g. calcium carbonate), sulfates,
Examples include sulfites (eg, calcium sulfate) and oxides (eg, talc, silica, alumina, etc.). These inorganic substances are useful because they can be easily obtained in large quantities at low cost, and the resulting blended compositions are highly usable. In particular, carbonates such as calcium carbonate easily undergo an endothermic decomposition reaction at the combustion temperature of plastics and leave less combustion residue than other inorganic fillers, so in order to obtain an easily incinerated resin composition, It is more purposeful.

However, conventional mineral-filled polyolefin resin compositions (
Although the filler composition (hereinafter simply referred to as "filling composition") is sufficient for extrusion molding, there was nothing noteworthy regarding injection molding.

This is because the change in fluidity polarity caused by the inorganic filling affects the release properties from the mold and the fluidity within the cavity.At the same time, in the case of injection molding, the resin flow is pulse-like. This is also thought to be because the cavity in the mold, which is filled with the injected resin, has a complicated shape, and slight changes in fluidity or polarity are amplified to a large effect. In order to solve the problems associated with injection molding, the present inventors conducted intensive research on the filling composition of polyolefin resin, which is consumed in the largest amount, and calcium carbonate, which is the most useful for reducing calories. 70 weight 70, preferably 45-65 weight? And 60-30wt of natural or synthetic calcium carbonate? , preferably 55 to 35 weight? One or more compounds selected from the group of paraffinic compounds and higher fatty acid compounds are added to 100 parts by weight of a compound consisting of 02 to 6.
0 parts by weight, preferably 0.5 to 4.5 parts by weight,
Melt index (ASTMD-1238230℃,
2160g/10 minutes. A filling composition having an MI (hereinafter abbreviated as MI) in the range of 6 to 24 has good mold releasability. We discovered that it has excellent moldability and appearance, and arrived at the present invention.

Regarding the blend of polypropylene and calcium carbonate in the present invention, if the calcium carbonate content is less than 30%, melt dripping will not be eliminated and a substantially effective reduction in burned calories cannot be expected. Moreover, if it exceeds 6070, the molded product will have a plaster-like appearance and there will be problems in terms of strength.
Furthermore, the amount of additive selected from the group of paraffinic compounds and higher fatty acid compounds is 0.2 parts by weight or less per 100 parts by weight of the blend of polypropylene and calcium carbonate, which substantially improves moldability and mold release properties. If the additive exceeds 6 parts by weight, free zinc will appear on the resin surface and the odor after molding will become strong, so it is not suitable for practical use.

Paraffin compounds include liquid paraffin, solid paraffin, waxes such as microcrystalline wax, and low molecular weight polyethylene and polypropylene. Higher fatty acid compounds include Cl2 to C22 straight chain fatty acids, metal salts thereof, and butyl alcohol esters. Refers to methylene and ethylene bisamide.

This filling composition also contains 6 known ultraviolet absorbers. Combination use with antioxidants, colorants, antistatic agents and other additives is also permissible. The effect of the additive according to the present invention is to improve the influence of the filler on fluidity and polarity, and the effect is exhibited when the MI of the final composition is in the range of 6 to 24. The mere presence of this does not indicate good moldability.

Conventionally, it has been well known that the above-mentioned lubricating substances are added to general plastic materials to improve mold release and moldability, but in the case of general plastic materials, M
Even those with a low I value (less than 6) do not have much problem with mold releasability and moldability, and are generally used by adjusting molding conditions, mold structure, etc.

However, when inorganic fillers are added, polarity and
Fluidity, shrinkage rate, dimensional stability, etc. vary greatly, and it is difficult to improve moldability and mold releasability using conventional methods, such as changing molding conditions and mold structure. This is a major reason why conventional materials containing inorganic fillers are not practical as resin raw materials for injection molding.

In the present invention. By setting the MI value to 6 to 24,
This is a new invention that solves these problems all at once, and cannot be understood from conventional common sense. The greatest effect of the present invention is that 6 molding companies can obtain low-calorie plastic molded products with molding efficiency equivalent to that of polypropylene without inorganic additives, using conventional molding machines, molds, and molding conditions. The benefits of this method are immeasurable, including the reduction of material costs by incorporating inorganic fillers, the saving of petroleum resources, the ease of incineration, and the high quality of the resulting products.

The composition according to the invention can be easily obtained using a common resin kneader, such as a Banbury mixer roll mill, an extruder, etc., and does not require any special equipment. Furthermore, during production, the additives specified in the present invention may be added to the polypropylene mixed with an inorganic filler in advance, or the polypropylene, the inorganic filler, and the 6 additives may be kneaded simultaneously. No difference in quality was found with either method. Hereinafter, the present invention will be explained in more detail with reference to specific examples.

Examples 1 to 14, Reference Examples 1 to 7 The raw materials shown in Table 1 were thoroughly kneaded using a high-speed mixer, pelletized using a screw-type granulator, and pelletized using an injection molding machine.
Nissei Jushi Kogyo Co., Ltd. (FS-150A, 50Z)] was used to mold a screw cap for cosmetic cream measuring 70 x 15 m/m (outer diameter x height) (melting temperature: 220-230°C automatic falling mold) The moldability, releasability, appearance, and strength were investigated using

The judgment method and criteria are as follows. (1) Molding mold: The molded product was observed for molding defects such as burrs, short shots, and flow marks.

○: No problem at all Δ: Some molding defects occur.

X: Significant molding defects.

(2) Mold releasability: During molding, the state of automatic falling of the molded product for each shot was observed.

○: No problem at all.

△: Once every 5 to 10 shots, mold outside strength Screw rubbing due to poor separation arise.

×: Release from the mold is extremely bad and significant. Causes screw friction.

Observation: gloss, flow marks, foaming of molded products observed.

○: Glossy and extremely good.

Δ: Slightly inferior gloss, flower Foaming can also be seen.

×: Lack of luster, flow marks, Foaming is significant.

Degree: The molded cap is filled with the contents. screwed onto a bottle (total weight approximately 3889), Falling upside down from a height of 1m, The state of damage to the spruce was observed.

○: No change at all.

△: Slight cracks occur after one drop. Sometimes.

×: Damaged by one drop.

(5) Overall evaluation: ○: No problem at all in practical terms.

△: There are some problems, but it is practical.

x: Not practical From Table 1, it can be seen that if the amount of additive added is O-0.1 part by weight, it cannot be put to practical use even if the blending ratio of polypropylene and calcium carbonate is changed.

Examples 16-18, Reference Examples 7-9M. I. Use polypropylene with different values. As in Example 1, a screw cap was molded and its properties were evaluated.

Claims (1)

[Claims] 1. One or more compounds selected from the group of paraffinic compounds and higher fatty acid compounds are added to 100 parts by weight of a mixture consisting of 40 to 70% by weight of polypropylene and 60 to 30% by weight of calcium carbonate. An easily inflammable polypropylene resin composition for injection molding, which has a melt index in the range of 6 to 24 and is added in an amount of 2 to 6.0 parts by weight.