JPH11172005A - Vinyl chloride resin composition for powder molding - Google Patents

Abstract

(57) [Problem] To provide a vinyl chloride resin composition for powder molding capable of obtaining a molded article having a uniform thickness without generation of bubbles and color spots. The surface of a vinyl chloride resin particle obtained by dry blending a plasticizer and a colorant has an average particle diameter of 1 to 3 μm.
A powder having a nominal size of 180 specified in JIS Z8801.
Less than 25% by weight, and less than 15% by weight of particles passing through a sieve having a nominal size of 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin composition for powder molding, which hardly causes color spots and bubbles on the surface of a molded product and can make the thickness of the molded product uniform.

[0002]

2. Description of the Related Art Molded articles manufactured by powder molding techniques, such as powder slush molding, have features that are not found in other molding methods, such as excellent three-dimensional shape, beautiful surface, and flexibility. In addition, automotive instrument panels,
It is frequently used as interior parts for automobiles such as door trims. In powder slush molding, concretely, a powder material is put into a mold, the powder material is attached to the mold surface by rotating the mold, excess material is discharged from the mold, and the powder The procedure is carried out in such a manner that the adhered powder material is sufficiently melted and then cooled, and the obtained molded product is separated from the mold.

[0003] The surface of a molded article produced in this way contains many fine bubbles even when observed with a low-magnification microscope. The bubbles seem to be practically not a problem unless they are visible to the naked eye, but can be large and visible to the naked eye depending on the molding conditions. When the number of fine air bubbles increases or large air bubbles are generated, durability is lowered, for example, cracks are generated from the air bubbles, and the commercial value is impaired. Similarly, molded articles having color spots lose their utility as, for example, automotive interior parts.

[0004]

The present inventors have conducted intensive studies to investigate the causes of bubbles and color spots in the powder molding technique. As a result, the cause of the bubbles was that a large amount of large particles were contained in the powder material. Therefore, when the powder material adheres to the mold, gaps are formed between the particles and the particles are not sufficiently filled, and the air accumulated in the gaps expands when the powder material melts, forming bubbles and forming molded products. In addition, the cause of the color unevenness is due to the unevenness of the colorant depending on the size of the particles of the powder material, and the degree of adhesion to the mold varies depending on the particle size of the powder material having a wide particle size distribution. I found it to be good.

[0005] In order to prevent the generation of air bubbles, the content ratio of particles larger than necessary in the powder material is reduced, and in order to prevent the occurrence of color spots, the particle size distribution of the powder material is sharpened. Was found to be effective.
However, if the particle size of the powder material is too small, the fluidity of the powder deteriorates, and it becomes difficult to obtain a molded product having a uniform thickness. Therefore, it has been found that a specific particle size distribution is necessary. That is, an object of the present invention is to provide a vinyl chloride resin composition for powder molding capable of obtaining a molded article having a uniform thickness without generation of bubbles and color spots.

[0006]

Means for Solving the Problems The gist of the present invention resides in that the surface of vinyl chloride resin particles obtained by dry blending a plasticizer and a colorant has an average particle diameter of 1 to 3.
a powder having a particle size of less than 25% by weight which does not pass through a sieve having a nominal size of 180 specified in JIS Z8801;
And a ratio of particles passing through a sieve with a nominal size of 106 is less than 15% by weight.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. As the vinyl chloride resin which is a resin component used in the vinyl chloride resin composition for powder molding of the present invention, a commercially available vinyl chloride resin can be used as it is. Specifically, a vinyl chloride homopolymer produced by a suspension polymerization method or a bulk polymerization method, or a copolymer mainly composed of a vinyl chloride monomer and a vinyl chloride monomer such as ethylene vinyl acetate is used depending on the purpose of use. These vinyl chloride resins are porous resins that can easily absorb a plasticizer when mixed with a plasticizer, that is, are capable of so-called dry blending. The average degree of polymerization of the vinyl chloride resin used is 700
Those in the range of ~ 1300 are desirable.

The above-mentioned vinyl chloride resin to be used in the vinyl chloride resin composition for powder molding is, in particular, JIS Z 88
01, that is, the aperture 250
μm through the sieve almost completely, nominal size 180, ie
The proportion of particles that do not pass through a sieve having an opening of 180 μm is less than 10% by weight, and the nominal size is 106, that is, the opening is 10%.
The use of particles having a particle size of 25% by weight or less passing through a 6 μm sieve and having a nominal size of 75, that is, having few particles passing through a sieve having a mesh size of 75 μm, can reduce the particle size and particle size distribution of the composition. Preferred for adjustment. Commercially available vinyl chloride resin produced by the suspension polymerization method,
Those having various particle size distributions and having the above-mentioned particle size distribution can be used as they are, but usually, the above-mentioned particle ratio is obtained by sieving. Further, the sieved vinyl chloride resin may be mixed and adjusted so as to be in the above-mentioned particle ratio range.

The plasticizer used for dry-blending with the vinyl chloride resin of the present invention is not particularly limited as long as it is commonly used for vinyl chloride resins. For example, phthalate ester plasticizer, trimellitic acid Examples include ester plasticizers, phosphate ester plasticizers, aliphatic dibasic ester plasticizers, epoxy plasticizers, polyester plasticizers, and the like. In particular, it is preferable to use a high-molecular weight plasticizer having a weight-average molecular weight of 430 or more in the composition used for the molded article for automobile interiors in order to prevent fogging of the window glass due to volatilization of the plasticizer. The blending amount of the plasticizer is limited when the vinyl chloride resin is still present in powder form when the plasticizer is mixed with the vinyl chloride resin powder,
Specifically, the amount is, for example, 20 to 100 parts by weight, preferably 40 to 80 parts by weight, per 100 parts by weight of the vinyl chloride resin.

Colorants used for dry blending the vinyl chloride resin composition of the present invention with a vinyl chloride resin include, for example, titanium white, carbon black, iron oxide red, cobalt blue, and titanium. Inorganic pigments such as yellow, titanium black and navy blue; organic pigments such as quinacridone red, dioxazine violet, perylene red, perylene permillion, perylene scarlet, perinone orange, azo red, isoindolinone yellow, and cyanine green. Alternatively, two or more of these pigments may be mixed and used in a gray color, a brown color, or the like. Of course, the colorant is not limited to those described above. The amount of the coloring agent to be added is suitably in the range of 1 to 15 parts by weight per 100 parts by weight of the vinyl chloride resin.

A heat stabilizer is usually added to the vinyl chloride resin composition for powder molding of the present invention. Examples of the heat stabilizer include various types of perchloric acid-treated hydrotalcite, perchloric acid-based stabilizers such as metal perchlorate, zeolite compounds, Ba-Zn-based composite stabilizers, and the like. Two or more types may be used in combination depending on the use of the vinyl chloride resin composition. Thus, the amount of the stabilizer is preferably 15 parts by weight or less, and more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the vinyl chloride resin.

The vinyl chloride resin composition for powder molding according to the present invention may contain various known additives, for example, a filler, a lubricant, an antioxidant, and an ultraviolet ray, depending on the purpose and use of the composition. An absorbent, a foaming agent, an antistatic agent and the like may be dry-blended as long as the physical properties of a molded article obtained from the composition are not deteriorated.

The vinyl chloride resin composition for powder molding of the present invention is produced by an emulsion polymerization method or a fine suspension polymerization method in order to improve the powder fluidity and to control the particle size distribution of the composition to a specific range. It is necessary to adhere a vinyl chloride resin having a mean particle size in the range of 1 to 3 μm, that is, a so-called vinyl chloride paste resin, to the particle surface of the dry-blended vinyl chloride resin. A vinyl chloride paste resin having an average degree of polymerization of 900 to 1700 is used. The amount of the vinyl chloride paste resin is usually 5 to 30 parts by weight, based on 100 parts by weight of the vinyl chloride resin.
Preferably, the range is 5 to 20 parts by weight.

The vinyl chloride resin composition for powder molding of the present invention comprises the above-mentioned porous vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method, a colorant, and, if necessary, other additives. Are mixed uniformly, then a plasticizer is added, and the mixture is heated until the temperature of the composition reaches about 120 ° C. to perform dry blending. Then, after cooling the dry blend to about 50 ° C., the average particle size is 1 to 3 μm.
The vinyl chloride resin is added in a predetermined amount, and the vinyl chloride resin is uniformly sprinkled on the surface of the dry-blended particles.

[0015] The polyvinyl chloride resin composition for powder molding thus prepared has a particle ratio of 25% by weight which does not pass through a sieve having a nominal size of 180 specified in JIS Z8801.
It is adjusted so that the ratio of particles passing through a sieve having a nominal size of less than 15% is less than 15% by weight. However, if necessary, the particles may be sieved again and adjusted to fall within the above range.

The vinyl chloride resin composition for powder molding of the present invention is obtained by dry-blending a commercially available vinyl chloride resin in the same manner as described above, and then adding a vinyl chloride resin having an average particle size of 1 to 3 μm. It may be manufactured by uniformly sprinkling and then sieving to obtain a predetermined particle size distribution. However, this method is not economical because it generates a large amount of unnecessary particles, involves difficult work in sieving, and is not economical. Therefore, it is desirable to adopt the former method.

In addition, when the vinyl chloride resin composition for powder molding of the present invention is prepared, when a vinyl chloride resin having an average particle diameter of 1 to 3 μm is added simultaneously with the dry blending,
The powder fluidity of the composition is impaired, and the effect of improvement is not sufficiently exhibited. In order to uniformly dry blend and mix these components, for example, they may be charged into a high-speed mixer such as a super mixer or a Henschel mixer or various mixers such as a ribbon blender and sufficiently stirred.

The vinyl chloride resin composition for powder molding of the present invention can be formed into a desired shape, for example, a crash pad, a door trim, a headrest, a console box, by a powder molding technique such as an engel method, a Heisler method, a Hayashi process, or a rotational molding method. It is highly useful as a molded product that is composited with a urethane resin such as a skin, that is, a molding material for automobile interior parts.

[0019]

EXAMPLES Next, the vinyl chloride resin composition for powder molding of the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. . Examples 1 to 4 and Comparative Examples 1 to 6 The vinyl chloride resins produced by the suspension polymerization method used in each example are as follows.

[0020]

[Table 1] Particle size distribution (nominal size, residual weight%) Average degree of polymerization Average particle size 250 180 150 106 75 75 (through) Example 1 800 135 μm 0 4 20 63 12 0 Example 2 800 130 μm 0 1 17 66 14 2 Example 3 800 140 μm 0 7 29 56 8 0 Example 4 1000 120 μm 0 0 2 82 16 0 Comparative Example 1 800 165 μm 0 31 39 36 4 0 Comparative Example 2 900 160 μm 0 24 37 34 5 0 Comparative Example 3 1000 157 μm 0 24 28 40 8 0 Comparative Example 4 1000 170 μm 0 36 37 24 3 0 Comparative Example 5 1000 145 μm 0 15 28 47 10 0 Comparative Example 6 800 112 μm 0 0 3 58 33 6

<Preparation of Vinyl Chloride Resin Composition for Powder Molding> The above-mentioned vinyl chloride resin 100 was added to a super mixer.
Parts by weight, 20 parts by weight of n-octyl trimellitate or a mixed alkyl phthalate of C ₉ , ₁₁ in the amount shown in Table 1, 5 parts by weight of epoxidized soybean oil, perchloric acid stabilizer 6
Parts by weight, 3 parts by weight of a dark brown inorganic pigment or a light brown inorganic pigment, and 1 part by weight of a benzophenone-based ultraviolet absorber were added and stirred.
When the temperature reached 05 ° C, the plasticizer that had been left in advance was additionally charged and stirred. When the composition temperature reached 120 ° C., the mixture was discharged into a cooling mixer, and the composition temperature was set at 5 ° C.
When the temperature reached 0 ° C., 10 parts by weight of a vinyl chloride paste resin having an average degree of polymerization of 1300 and an average particle diameter of 1 μm was added, and the mixture was stirred for 3 minutes to coat the resin on the surface of the dry-blended particles. Table 1 shows the average particle size and particle size distribution of the vinyl chloride resin composition for powder molding thus prepared.
It was shown to.

<Manufacture of molded article> 770 mm × 450 mm
Of about 200 mm in depth,
The mixture was heated to a mold temperature of 210 ° C. with oil heated to 0 ° C., and then the above-described composition was charged into the mold and capped.
The mold was rotated so that the composition adhered to the mold surface to a thickness of about 1 mm, and the composition that did not adhere was discharged.
After the composition was melted for 2 minutes, the outer surface of the mold was cooled with water, and the molded product was peeled from the mold.

The state of air bubbles, unevenness of color, and uniformity of thickness of the molded article were observed and are shown in Table 1. In addition, in the same composition except for the pigment, the dark brown color inorganic pigment and the light brown color inorganic pigment were respectively added, the state of the air bubbles, the evaluation results of the uniformity of the thickness were the same, each Example In the Comparative Examples, the evaluation of color spots was also described. <
Evaluation method> Bubble condition; Observation of the surface of the molded article with a microscope ◎: Small and small bubbles ○: Slightly large bubbles
×: Large bubbles Color spot; Visual observation of molded article surface ◎: None ○: A little ×: Clearly noticeable Thickness uniformity; Visual observation of swelling of molded article backside, presence or absence of composition lump ○: None ×: Partial With swelling of the composition

[0024]

[Table 2]

As is clear from the examples, by using the vinyl chloride resin composition for powder molding having a specific particle size distribution as in the present invention, bubbles and color spots on the surface do not occur.
In addition, a molded product having a uniform thickness can be obtained.

[0026]

According to the present invention, the use of a vinyl chloride resin composition in which the particle ratio is adjusted to have a specific particle size distribution is used for powder molding, so that air bubbles and color spots on the surface are eliminated and uniform. Since it is a molded article having a beautiful surface and excellent appearance with excellent smoothness and durability, it is highly useful as interior and exterior parts for automobiles and as interior and exterior parts for construction.

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[Procedure amendment]

[Submission date] January 13, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

The above-mentioned vinyl chloride resin to be used in the vinyl chloride resin composition for powder molding is, in particular, JIS Z 88
01, that is, the aperture 250
μm through the sieve almost completely, nominal size 180, ie
The proportion of particles that do not pass through a sieve having an opening of 180 μm is less than 10% by weight, and the nominal size is 106, that is, the opening is 10%.
The use of particles having a particle size of less than 25% by weight passing through a 6 μm sieve and having a nominal size of 75, ie, with few particles passing through a 75 μm mesh sieve, reduces the particle size and particle size distribution of the composition. Preferred for adjustment. Commercially available vinyl chloride resin produced by the suspension polymerization method,
Those having various particle size distributions and having the above-mentioned particle size distribution can be used as they are, but usually, the above-mentioned particle ratio is obtained by sieving. Further, the sieved vinyl chloride resin may be mixed and adjusted so as to be in the above-mentioned particle ratio range.

Claims (5)

[Claims] An average particle diameter of 1 to 3 μm is applied to the surface of vinyl chloride resin particles obtained by dry blending a plasticizer and a colorant.
A powder having a nominal size of 180 specified in JIS Z8801.
Less than 25% by weight, and less than 15% by weight of particles passing through a sieve having a nominal size of 106. 2. The vinyl chloride resin composition for powder molding according to claim 1, wherein the particles of the vinyl chloride resin used for the dry blending are porous particles produced by a suspension polymerization method or a bulk polymerization method. 3. The vinyl chloride resin used for dry blending has a particle ratio of less than 10% by weight which does not pass through a sieve having a nominal size of 180 specified in JIS Z 8801 and a particle ratio which passes through a sieve having a nominal size of 106. 3. The vinyl chloride resin composition for powder molding according to claim 1, wherein the content is less than 25% by weight. 4. The vinyl chloride resin composition for powder molding according to claim 1, wherein the average degree of polymerization of the vinyl chloride resin used for the dry blending is in the range of 700 to 1300. 5. The average degree of polymerization of the vinyl chloride resin having an average particle diameter of 1 to 3 μm is in the range of 900 to 1700.
The vinyl chloride resin composition for powder molding according to any one of claims 1 to 4.