JPH01165646A - Vinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition for powder molding excellent in powder flow and heat meltability, by mixing a specified vinyl chloride resin with a plasticizer. CONSTITUTION:Vinyl chloride (a) is polymerized in bulk with optionally a monomer (b) copolymerizable with component (a) (e.g., ethylene) to obtain a vinyl chloride resin (A) of a degree of polymerization of 400-3000, desirably 600-1200, a particle diameter range of 50-300, preferably 70-250mum and a porosity of 0.17-0.25, preferably 0.18-0.22cc/g. 100 pts.wt. component A is mixed with 50-100 pts.wt. plasticizer (B) (e.g., diisodecyl phthalate) and optionally a stabilizer (aid), a processing aid, a filler, a dusting powder, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a vinyl chloride resin composition for powder molding.

More specifically, the present invention relates to a vinyl chloride resin composition for powder molding that is particularly effective in processing fields that require powder fluidity and heat meltability.

[Prior Art and Problems] Various methods have been conventionally used for molding vinyl chloride resin.

Among these, examples of powder molding methods include rotational molding, powder slush molding, and fluidized dip coating.

Examples include electrostatic coating method and powder coating method.

In these powder molding methods, the properties required for the raw resin powder are good powder fluidity and heat meltability, which is necessary for the uniform thickness of the products obtained using this. This is to make it easier for the raw material powder to penetrate into details such as undercuts, and if the meltability is good, it can be processed at a lower temperature, thus preventing thermal deterioration.

Conventionally, various studies have been made to improve the powder fluidity and heat meltability of vinyl chloride resin compositions.

For example, consider the dusting agent to be added to improve the powder fluidity after mixing the resin and other additives, and consider the type of raw material resin, such as using a copolymer, to improve the heat meltability. However, satisfactory results have not yet been obtained.

Furthermore, in conventional powder molding vinyl chloride resin compositions,
Powder fluidity and meltability are insufficient, and as a result, (1) the powder does not adhere uniformly to the mold, and (2) the powder does not penetrate into complex-shaped parts such as undercuts.

(3) Melting is insufficient and leveling properties are poor.

(4) Melting is uneven and the thickness is not uniform.

(5) There are problems such as incomplete defoaming and poor mechanical strength due to the large number of bubbles in the product.Furthermore, if the meltability of the resin is not sufficient, the molding process will take place at high temperatures (220-240°C). ), the thermal stability of the vinyl chloride resin itself and of the organic pigments used as a type of additive becomes a problem.

In order to improve the meltability of resins, the use of vinyl chloride resins with a low degree of polymerization and copolymers with a low softening temperature is being considered.

However, although these methods improve the problem with the meltability of the resin, problems with thermal stability and mechanical strength remain, and problems still remain in practical use.

There is also a method of using a large amount of plasticizer for the resin,
This method tends to cause blocking during mixing of the plasticizer and resin, and the plasticizer may not penetrate completely into the resin, resulting in extremely poor powder fluidity of the resulting powder resin composition.

Furthermore, if a vinyl chloride resin without a skin layer (for example, a layer of polyvinyl alcohol (PVA)) obtained by a suspension polymerization method is used to improve the meltability and oil absorption of the resin, the resulting resin composition Although the meltability of the particles is improved, the particles tend to disintegrate during mixing with additives such as plasticizers,
Powder fluidity is poor due to the formation of many irregularly shaped small particles in the resin composition, and the resin composition that does not adhere to the mold during molding (
(recovered and used), fused particles will be mixed in, and if such a composition is repeatedly used and processed, pinholes etc. are likely to occur on the product surface.

Many problems still remain in the application of vinyl chloride resin obtained by such a relatively simple suspension polymerization method to powder molding processing.

[Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have conducted various studies on the differences in physical properties of products produced by the polymerization method of vinyl chloride resin, and have found that:
It has been found that vinyl chloride resin obtained by bulk polymerization has even better meltability than that obtained by suspension polymerization, and is suitable as a vinyl chloride resin composition for powder molding.

Similarly, in order to obtain a vinyl chloride resin composition with excellent powder fluidity without reducing thermal stability and mechanical strength, as a result of intensive studies on the vinyl chloride resin that serves as the base material, we have found that the following conditions are satisfied. The present inventors have discovered that the object can be achieved by using a resin that has the following properties, and have completed the present invention.

That is, the present invention provides particles having a particle size range of substantially 50 to 300 μn and a porosity of 0, obtained by a bulk polymerization method.
．． The present invention relates to a vinyl chloride resin composition for powder molding, which comprises a vinyl chloride resin and a plasticizer, and a plasticizer.

The present invention will be explained in detail below.

The vinyl chloride resin used in the present invention is a vinyl chloride resin obtained by a bulk polymerization method, and more specifically, a vinyl chloride homopolymer and a copolymer with a monomer copolymerizable with a vinyl chloride monomer. Refers to vinyl chloride resin.

The bulk polymerization method for obtaining the polymer used in the present invention is not particularly limited, and may be a general vinyl chloride bulk polymerization method, for example,
This method involves obtaining a seed polymer in the first stage polymerization and growing it in the second stage polymerization to obtain a polymer.

Monomers copolymerizable with vinyl chloride monomers include, for example,
Ethylene, propylene, butene, pentene-1, butadiene, styrene, α-methylstyrene, acrylonitrile, vinylidene chloride, vinylidene cyanide, alkyl vinyl ethers, carboxylic acid vinyl esters, aryl ethers, dialkyl maleates, fumaric acid esters , N-vinylpyrrolidone, vinylpyridine, vinylsilanes, acrylic acid alkyl esters, methacrylic acid alkyl esters, and the like.

The degree of polymerization of the vinyl chloride resin used here varies depending on the molding method, molding conditions, and application, but it can range from 400 to 3,000, which is used in ordinary soft vinyl chloride resin compositions.

For powder molding, those having a degree of polymerization of 600 to 1200 are desirable.

The vinyl chloride resin used in the present invention is obtained by bulk polymerization, and it is essential that the particle size range is substantially 50 to 300 μ- and the porosity is 0.17 to 0.25 cc/g. do.

If the particle size distribution of the resin is out of this range, the powder fluidity and meltability when formed into a composition will be poor, and blocking will likely occur during mixing with other additives and during molding. In the present invention, a more preferable particle size range of the vinyl chloride resin is 70 to 250 microns.

Note that the resin having the particle size range described above can also be obtained by appropriately classifying the resin obtained by polymerization and adjusting the particle size.

In the present invention, porosity refers to the degree of porosity of particles,
In the present invention, values obtained by mercury porosimetry were used.

The larger this value is, the greater the amount of plasticizer etc. absorbed.

In the present invention, if a resin with a porosity of less than 0.17 cc/g is used, the necessary amount of plasticizer will not be absorbed into the resin when mixed with a plasticizer, and therefore the plasticizer will not be absorbed between the resin particles. remains, which deteriorates the powder fluidity of the resulting composition.

If the same <0.25g + 1/g is exceeded, depending on the amount of plasticizer used, for example, if less than 100 parts by weight of plasticizer is used for 100 parts by weight of resin, the bulk specific gravity of the composition will decrease, This is not preferable when molding using this.

In the present invention, a more preferable porosity value of the vinyl chloride resin is 0.18 to 0.22g+1/g.

In the present invention, the plasticizer added to the vinyl chloride resin is not particularly limited, and examples include di-N-butyl phthalate, di-2-ethylhexyl phthalate (DOP), and di-N-butyl phthalate.
Phthalic acid plasticizers such as N-octyl, diisooctyl phthalate, octyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl isophthalate, di-2-ethylhexyl adipate (D
OA), fatty acid ester plasticizers such as di-N-decyl adipate, diisodecyl adipate, di-2-ethylhexyl adipate, dibutyl sebacate, di-2-ethylhexyl sebacate, tributyl phosphate, tri-2-ethylhexyl phosphate , phosphate esters such as tri-2-ethylhexyldiphenyl phosphate and tricresyl phosphate, and epoxy plasticizers such as epoxidized soybean oil and epoxidized linseed oil, or liquid epoxy resins, and one or more of these. use. Although the liquid epoxy resin described above is slightly different from a secondary plasticizer such as epoxidized soybean oil, it contributes to the thermal stability of the resin composition in the same way as an epoxy plasticizer such as epoxidized soybean oil, and Since it is a liquid, it can be included in the category of epoxy plasticizers in the composition of the present invention.

The amount of the above-mentioned transportability agent added is preferably 50 to 100 parts by weight of the plasticizer per 100 parts by weight of the resin.

Furthermore, if necessary, stabilizers may be used, such as metal soap stabilizers such as zinc stearate, calcium stearate, barium stearate, and cadmium stearate, and tin-based stabilizers such as tin laurate and tin maleate mercapto. Can be done.

Furthermore, if necessary, inorganic and organic compounds can be blended as commonly used stabilizing aids, processing aids, fillers and dusting agents.

In addition, preferable results can also be obtained by using a so-called non-porous base resin obtained by a fine suspension polymerization method as a fluidity improver (powdering agent) of the composition. The amount of paste resin used at this time is 5 to 2 parts by weight per 100 parts by weight of resin.
It is 0 parts by weight.

[Effects of the Invention] The vinyl chloride resin composition for powder molding of the present invention has excellent powder flowability and meltability, and products molded using the same have uniform wall thickness with no underfill, making it easy to use for molding. Aggregates are not included in the powder that is later collected and reused.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 11 Comparative Examples 1 to 4 In a Henschel mixer with an internal volume of 10 L, bulk polymerization method (normal method using a seed polymer), suspension polymerization method (containing vinyl chloride monomer and PVA in a water flask medium) 1 kg of straight vinyl chloride resin obtained by adding a dispersant, a polymerization initiator, etc., and performing polymerization by heating and stirring), which was appropriately classified.

30g of Ba-Zn composite powder stabilizer was charged, heated while stirring at a constant rotational speed, and triblended with 700g of diisodecyl phthalate and 80g of epoxy plasticizer added as plasticizers, and when the temperature reached 120℃. This blend was cooled, and when the resin temperature became 60°C or less, 120g of paste resin obtained by the fine suspension polymerization method was added.
A powdered resin composition was obtained after the mixture was added to this and stirring was continued.

The bulk specific gravity (JIS K 8
721 method), and the angle of repose (cylindrical rotation method...using a cylindrical rotation type flow surface measurement device manufactured by Tsutsui Rikagaku Instruments).

An automobile armrest scale mold made of copper-nickel plywood was preheated by placing it in an oven at 240°C, and after bringing the mold temperature to 200°C, it was taken out of the furnace, and the powder composition was immediately poured into it. After shaking for 10 seconds, the unadhered powder was discharged, and the mold was placed in a heating furnace at 240°C again and molded for 3 minutes. The uniformity of the wall thickness was visually evaluated. Moreover, the blocking property was evaluated based on the amount of aggregates (blocking substances) of unattached powder when this operation was repeated 10 times.

In addition, the borosity is ASTM (ASTM Bul, 23
6:39-44 Feb, 1959)
Δ-1 was determined using POROCI METER manufactured by NCO. The results are shown in Table-1.

Table-1 Example 1 Comparative Example 1 2 3 4 Polo '7 Tee 0.21 0.21 0.28 0.
18 0.45 (m17g) Degree of polymerization 950 950 1050 800
1050 Bulk specific gravity* 0.63 0.61 0.
57 0.8 0.45 (g/ml) Angle of repose 29 30 32 30>40
Di) Leveling property AAABB Thickness AABDC Thickness uniformity AABCD Blocking property ACBCD * indicates the bulk specific gravity of the composition.

The following polymers were used.

Polymer obtained by bulk polymerization method classified into 70-250 μm (Example 1, Comparative Example 2) Same red classification (Comparative Example 1) Polymer obtained by suspension polymerization method classified into 70-250 μm (Comparative Example 3.4) In the table, A to D were judged based on the following criteria.

[Leveling property] Visually judge the smoothness of the product surface (powder discharge side) for the presence or absence of unmelted particles, surface waving, and gloss. A: Excellent in all respects.

B: There are no unmelted particles and there is luster, but waving is observed.

C: Poor surface smoothness and low gloss.

D: Unmelted particles are observed.

[Undercut property] Judging by visual inspection of the entire product, especially the undercut part, A: Excellent in all respects.

B: Thin undercut portion.

C: The undercut part is partially lacking in thickness.D: The lack of thickness is continuous and cutting occurs due to tension.

[Thickness Uniformity] Judgment is the same as for lack of thickness, especially the thickness of the sheet-like portion is measured using a thickness gauge, and evaluation is A: The thickness is within 5% of the average thickness.

B: Only the undercut portion deviates from 5%.

C: The thickness uniformity of the undercut portion is particularly poor, and the thickness of the sheet portion also slightly deviates from 5%.

D: The thickness uniformity of the sheet portion is extremely poor.

[Blocking property] Amount of blocking substances in repeatedly used dung bound particles A: None.

B: A small amount comes out when used repeatedly 10 times.

C: A small amount comes out after repeated use several times.

D: A small amount comes out when used repeatedly.

Example 2 Vinyl chloride polymer obtained by suspension polymerization method (particle size nia 0 to 20
0μ■, porosity: 0.2aL/g, degree of polymerization:
800) Vinyl chloride polymer obtained by bulk polymerization method (particle size: 0 to 200 μl, volume: 0.21 mL/g
% degree of polymerization: 900), a comparative test of meltability was conducted.

Nickel/copper (thickness Ni 2m) was placed in an oven at 300°C.
Plywood (Cu 3sn 20cm After standing, the mold was cooled with water and removed from the mold.The same compound as in Example 1 was used.

The defoaming properties and leveling properties were evaluated.

The results are shown in the table below.

The symbols in the table have the following meanings.

O: Both defoaming property and leveling property are good Δ: Defoaming property is poor, leveling Sumiyoshi The mechanical properties were improved.

Claims (1)

[Claims] Obtained by bulk polymerization method, with a particle size range of substantially 50 to 30
0 μm and porosity of 0.17 to 0.25
mL/g of a vinyl chloride resin composition for powder molding comprising a vinyl chloride resin and a plasticizer.