JPH08120111A - Flexible polyolefin resin granule - Google Patents

Abstract

PURPOSE: To obtain granules having the surface coated with crystalline polyolefin, improved in surface tackiness, capable of smoothly charging and dropping into a hopper of a molding equipment without causing blocking in storage and ready to handle. CONSTITUTION: These flexible resin granules have the surface coated with a crystalline polyolefin. A flexible polyolefin resin having <=80Joule/g crystal- melting calorie is used as the flexible polyolefin resin and a blend of an amorphous polyolefin with a crystalline polyolefin is used as the resin. Concretely, the flexible resin is produced by blending polypropylene, etc., with a propylene homopolymer, etc. The coated granules are produced by using a dice having a sheath-core (double tube) structure and producing a molding having a double layer structure containing crystalline polyolefin as the outer layer by a co- extrusion method and cutting the resultant molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft polyolefin resin granule having improved surface tackiness. More specifically, the present invention provides a granulated product which is not blocked during storage of the granulated product by improving the surface tackiness of the soft polyolefin resin granulated product.

[0002]

2. Description of the Related Art Soft polyolefin resin is a soft chlorinated resin that has social factors such as toxicity and transfer due to bleeding out of plasticizers and monomers, and acid rain due to generation of hydrogen chloride during incineration. Used as an alternative material to vinyl resin, pollution-free, flexibility, mechanical strength,
It has excellent features such as transparency. From this point, the soft polyolefin resin is preferably used as a soft film raw material, various hot melt resin raw materials and the like. However, since the soft polyolefin resin contains a large amount of an amorphous component having a relatively low molecular weight, the granules have strong surface tackiness, and blocking during storage of the granules and storage of the granules is severe. It was difficult to take out the granules, and there was a problem that the supply to the extruder was hindered. Therefore, a method of adhering powder particles to the surface of the granulated body (Japanese Patent Laid-Open No. 58-6923).
No. 8, JP-A-1-317709) and the like have been studied. However, even these methods are not sufficiently effective, or when the powder particles attached to the surface of the granule are used as a molding raw material for the film, sheet, etc., the characteristics such as transparency of the molding are adversely affected. There were problems such as

[0003]

The present invention has solved the drawbacks of soft polyolefin resin granules by providing a soft polyolefin resin granule whose surface is coated with a crystalline polyolefin. The soft polyolefin resin of the present invention has adhesiveness on the surface and is preferably applied to those having a heat of crystal fusion of 80 Joule / g or less. If it is higher than 80 Joule / g, the crystallinity is too high and the resin lacks flexibility and cannot be called a soft polyolefin resin. The soft polyolefin resin of the present invention may be produced all at once in the polymerization stage so that the heat of fusion of crystal is within the above range, or may be produced by blending a substantially amorphous polyolefin and a crystalline polyolefin. Good. As a method for producing all at once in the polymerization stage, known techniques such as transition metal compounds and organometallic compounds are used.
Ziegler-Natta-based catalysts for ethylene, propylene,
Butene-1, pentene-1, hexene-1, heptene-
1, homopolymers of α-olefins such as octene-1,
Examples thereof include a method of producing a copolymer, a ternary copolymer and the like in a gas phase, a block, a slurry and a solution. As a method for adjusting the heat of fusion of crystals so as to fall within the above range, this can also be easily achieved by changing a known method, the type of catalyst component, the amount used, the amount added of the electron donor, the polymerization temperature / pressure, etc. To be done.

The amount of heat of crystal fusion was measured as follows. Shimadzu DS as a differential scanning calorimeter
The sample amount was about 10 mg using C-50, the measurement atmosphere was a nitrogen atmosphere, and indium was used as a calorific value standard. The heating program is as follows. First, the sample is heated to 210 ° C. at a heating rate of 50 ° C./min and left at 210 ° C. for 5 minutes,
Cool to -42 ° C at a temperature decrease rate of 10 ° C / min and leave at -42 ° C for 5 minutes. After that, at a temperature rising rate of 20 ° C / min, -40
The measurement was performed from ℃ to 200 ℃. The heat of fusion of crystals was calculated by using a straight line obtained by extrapolating the specific heat curve of the sample in a completely molten state directly to the low temperature side as a baseline.

When blending the amorphous polyolefin and the crystalline polyolefin, which is another method for producing the soft polyolefin resin used in the present invention, a composition of the amorphous polyolefin and the crystalline polypropylene is preferably used. . The above-mentioned amorphous polyolefin means a boiling n
-Heptane-insoluble matter, that is, Soxhlet extractable insoluble matter by boiling n-heptane is 70% by weight or less, preferably 60
% By weight or less. Boiling n-heptane insoluble matter is 7
When the content is more than 0% by weight, the ratio of the amorphous portion is small, and the softness is poor and the characteristic as a soft polyolefin is not exhibited. As the amorphous polyolefin, those having a large number of low molecular weight components and a number average molecular weight of 20,000 or less are particularly preferably applied. As the amorphous polyolefin used in the present invention, for example, amorphous polypropylene, a copolymer of amorphous propylene and another α-olefin, or the like can be used. For example, atactic polypropylene produced as a by-product during the production of crystalline polypropylene may be used, or it may be produced from raw materials and used. In the case of target production, for example, a titanium-supported catalyst supported on magnesium chloride and triethylaluminum are used in the presence of hydrogen /
Alternatively, it can be obtained by polymerizing a raw material monomer in the absence of hydrogen. From the viewpoint of the stability of the raw material supply and the stability of the quality, it is preferable to use the predetermined amorphous polyolefin produced in the intended manner. Moreover, if there is a suitable and suitable commercial product, a commercially available product can be appropriately selected and used.

Specific examples of the amorphous polyolefin of the present invention include polypropylene, propylene / ethylene copolymer, propylene / butene-1 copolymer, and propylene.
Butene-1, ethylene-3 terpolymer, propylene / hexene-1, octene-1-3 terpolymer, propylene / hexene-1,4-methylpentene-1-3 terpolymer, polybutene-1 And so on. As the crystalline polyolefin blended with the amorphous polyolefin, crystalline polypropylene is preferably used because of its compatibility with the amorphous polyolefin.

Crystalline polypropylene includes polypropylene which is usually commercially available for extrusion molding, injection molding, blow molding and the like. In this case, it may be a propylene homopolymer or a copolymer of isotactic polypropylene having stereoregularity and another α-olefin. The crystalline polypropylene may be a commercially available product, or may be produced and used. The production of crystalline polypropylene is not particularly limited and can be appropriately selected and applied from the conventional methods for producing crystalline polypropylene.

The α-olefin used for copolymerization with the crystalline polypropylene is α-olefin having 2 to 8 carbon atoms.
-Olefins such as ethylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and the like are preferred. Among these, ethylene or butene-1 is particularly preferable.

In the present invention, the crystalline polypropylene is preferably a propylene homopolymer, a propylene / ethylene random copolymer or a block copolymer containing 30% by weight or less, preferably 1 to 25% by weight of an ethylene component. Examples thereof include a random copolymer and a block copolymer of propylene / butene-1 containing 20% by weight or less of butene-1. The crystalline polypropylene may be used alone or in combination of two or more.

Furthermore, the amorphous polyolefin and / or the crystalline polypropylene in the present invention may be modified. The above-mentioned amorphous polyolefin and / or crystalline polypropylene is used as an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid and / or their esters, and acid anhydrides. , And its derivatives such as metal salts can be modified before use. Among these modified products, those modified with maleic anhydride or itaconic anhydride are preferably used, and more preferably those modified with maleic anhydride are used. The method for producing a soft polyolefin resin granule whose surface is coated with a crystalline polyolefin is not particularly limited.

In the present invention, a method for preparing a soft polyolefin comprising a composition of an amorphous polyolefin and a crystalline polyolefin is a conventionally used method, for example, a kneader such as a kneader, a Banbury mixer or a roll,
It can be carried out by heating, melting and kneading using a single-screw or twin-screw extruder.

In the present invention, the crystalline polyolefin to be coated may be a crystalline α-olefin such as ethylene or butene-in addition to the crystalline polypropylene used in the blend with the amorphous polyolefin in the production of the soft polyolefin resin. 1, homopolymers such as 1, pentene-1, hexene-1, heptene-1, octene-1, and copolymers. Among these crystalline polyolefins, those having a relatively small amount of low molecular weight components, and having a number average molecular weight of 10,000 or more, preferably 2 for the purpose of the present invention.
Over 10,000 are used. In the soft polyolefin resin granule, the crystalline polyolefin layer needs to have a thickness of at least 10 μm or more. When the thickness is less than 10 μm, the low molecular weight component contained in the granules bleeds out and blocking occurs during storage of the granules, which is not preferable.

The surface of the soft polyolefin resin coated with the crystalline polyolefin in the present invention does not particularly mean the entire surface, but can be achieved as long as the surface is not tacky in its usage form. It The method for producing the soft polyolefin resin granules is not particularly limited, but a die having a sheath-core (double tube) structure was used to produce a molded product having a two-layer structure having a crystalline polyolefin as an outer layer by a coextrusion method. Examples include a method of post-cutting, a method of coating the outer surface of a preformed soft polyolefin strand or pellet with a crystalline polyolefin melt or solution, and the like. All of these can be easily realized by known techniques.

[0014]

EFFECTS OF THE INVENTION The soft polyolefin resin granules of the present invention have improved surface tackiness, do not block during storage, and fall smoothly when placed in the hopper of a molding machine, and are easy to handle. is there.

[0015]

[Examples and Comparative Examples]

Example 1 A die having a sheath core (double pipe) structure was attached to the tip of a twin-screw extruder having a screw diameter of 30 mmφ. The outer diameter of the double tube nozzle of the die was 5 mmφ and the inner diameter of the nozzle was 3.5 mmφ. The raw polymer fed from the hopper of the twin-screw extruder is melted by the twin-screw extruder and then split into the outer nozzle of the die. Moreover, in the inner nozzle part,
Another raw material polymer melted by a premelter (Meltop NK3-50 type, manufactured by Taiyo Giken Co., Ltd.) was introduced through a connecting pipe. In the primerta, a propylene / butene-1 copolymer as an amorphous polyolefin (trade name: UBETAC UT2780, manufactured by Ube Lexen Co., Ltd., a propylene / butene-1 weight ratio of 65 /
35, number average molecular weight 6,500). In the hopper of the twin-screw extruder, crystalline polypropylene (trade name RE386 Ube Industries, Ltd.) is used as crystalline polyolefin.
Manufactured, number average molecular weight 39,000) was supplied. The amorphous polyolefin supplied to the primerter is at a temperature of 160 ° C. at the inner nozzle of the double-tube structure die, and the crystalline polypropylene supplied from the hopper of the twin-screw extruder is at a temperature of 220.
After being divided into the outer nozzle portions at 0 ° C., they were extruded in a molten state from the nozzle outlet portions. The extruded melt was taken in a strand shape, cooled in water, and then cut to obtain a columnar granule (pellet). When the vertical cross section of the obtained columnar pellet was observed with a microscope, it was found to have a substantially concentric two-layer structure. The weight ratio of the amorphous polyolefin of the inner layer / the crystalline polypropylene of the outer layer calculated from the cross-sectional area of each layer was 50/50, and the thickness of the crystalline polypropylene part of the outer layer was about 0.5 mm, which were substantially uniform. After melting and kneading the obtained pellets, a film sample was prepared and the heat of crystal fusion measured by the above method was 34 Joule / g.
Met. Next, the obtained pellets were left in an air atmosphere (gear oven) at a temperature of 60 ° C. Then, the pellet was taken out periodically and the blocking state of the pellet was observed. At the same time, 90 g of the pellet in a truncated cone-shaped paper container having an upper opening inner diameter of 70 mmφ and a lower opening inner diameter of 50 mmφ.
It was filled and the time until all the pellets dropped from the container was measured. The shorter the dropping time is, the less the surface tackiness of the pellet is. The method of displaying the observation result of pellet blocking state is as follows. ◯: No blocking at all Δ: Slight blocking is observed ×: Vigorous blocking is shown in Table 1.

[0016]

[Table 1]

Example 2 The same amorphous polyolefin and crystalline polyolefin as in Example 1 were used, and the amorphous polyolefin / crystalline polyolefin was melt-kneaded at a weight ratio of 50/50 in a twin-screw extruder. The latter was extruded into a strand, cooled in water, and then wound in a strand. Next, the same crystalline polypropylene as that used in Example 1 (trade name RE
386 Ube Industries, Ltd. was dissolved in toluene at a temperature of 100 ° C. The crystalline polypropylene concentration was 7.5% by weight. The rolled-up strand was dipped in a toluene solution of crystalline polypropylene and dried in air to form a coating layer of crystalline polypropylene on the surface layer of the strand. A cylindrical granule (pellet) was obtained by cutting the strand.
When the vertical cross section of the obtained columnar pellet was observed with a microscope, the coating thickness of the crystalline polypropylene was about 20 μm.
Met. The heat of crystal fusion of this pellet measured by the above method was 35 Joule / g. The obtained pellets were evaluated in the same manner as in Example 1.

COMPARATIVE EXAMPLE 1 The same amorphous polyolefin as used in Example 2 /
A strand obtained by melt-kneading a crystalline polyolefin at a weight ratio of 50/50 is cut as it is, without being immersed in a toluene solution of crystalline polypropylene, to form a cylindrical granule (pellet). Got
The obtained pellets were evaluated in the same manner as in Example 1.

Claims (1)

[Claims] 1. A soft polyolefin resin granule having a surface coated with a crystalline polyolefin.