JPS648661B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride resin composition for powder molding that does not undergo thermal deterioration and has excellent powder flow characteristics and melting characteristics during molding or coating. Recently, various molding methods and coating methods using finely powdered synthetic resins have been developed, and typical examples include rotational molding, powder coating, fluidized dip coating, and electrostatic coating. For example, rotational molding is a method in which a synthetic resin is sintered along the inner surface of a desired mold to create an integral amalgam, while fluid dip coating is a method in which a synthetic resin is sintered into a heated object to be coated. This method involves melting the adhered surface resin powder to form a resin coating. The synthetic resins used in these molding and coating methods are required to have excellent powder flow characteristics and melting characteristics, and are also desired to be stable so as not to cause thermal deterioration during heating. However, the synthetic resins used for these powder moldings are mostly powdered polyethylene, polypropylene, polyamide, polycarbonate, acetal resin, and styrene resin, and vinyl chloride resin is rarely used. PVC resin has excellent physical properties such as mechanical strength, chemical resistance, and weather resistance.
Although it is relatively inexpensive, various attempts have been made to utilize it, and to date no satisfactory results have been obtained. Vinyl chloride resins manufactured by suspension polymerization and bulk polymerization, for example, have excellent powder flow characteristics, but have poor melting characteristics, so efforts are made to improve the melting characteristics by adding plasticizers. ing. and,
The lower the degree of polymerization of vinyl chloride resin, the better the melting properties tend to be. The plasticizer concentration is too high, which results in poor powder flowability. In addition, vinyl chloride resins produced by emulsion polymerization or fine suspension polymerization mixed with plasticizers have good melting properties, but because the plasticizers are not easily absorbed by the resin, the plasticizers may be deposited on the surface of the vinyl chloride resin. The particles adhere to each other, resulting in significantly poor powder fluidity. Furthermore, there is a method of mixing a vinyl chloride resin with a large particle size manufactured by suspension polymerization or bulk polymerization, a vinyl chloride resin with a small particle size manufactured by emulsion polymerization or fine suspension polymerization, and a plasticizer together. Powder fluidity tends to be poor due to the plasticizer on the particle surface. As an interim measure, Japanese Patent Publication No. 56-13727 describes powdered polyvinyl chloride containing a plasticizer with an average particle size of 10 to 70μ and powdered polyvinyl chloride without plasticizer having an average particle size of 0.1 to 5μ. A composition consisting of the following has been proposed. Although this composition has improved powder fluidity and somewhat satisfactory results have been obtained, the composition does not have sufficient melting properties and requires heating to high temperatures in order to obtain sufficient coating strength. It is necessary to melt the vinyl chloride resin by heating, and when doing so, there is a drawback that thermal deterioration of the vinyl chloride resin is likely to occur. In view of the above-mentioned circumstances, the present inventors conducted intensive studies to provide a powder molding composition that does not cause thermal deterioration and has excellent powder flow characteristics and melting characteristics. The present inventors have discovered that by incorporating a plasticizer into the powder, the powder flow characteristics remain unchanged, the melting characteristics are good even at a low melting temperature, and no thermal deterioration occurs, and the present invention has been completed. That is, the object of the present invention is to prevent thermal deterioration and
The purpose is to provide a vinyl chloride resin composition for powder molding that has good powder flow characteristics and melting characteristics. Powdered vinyl chloride resin composition A with an average particle diameter of 30 to 300μ obtained by cooling after drying, and powdered vinyl chloride resin composition B containing a plasticizer with an average particle diameter of 5μ or less,
This can also be achieved with a powder moldable vinyl chloride resin composition mixed without heating. To explain the present invention in detail, vinyl chloride resin composition A, which is one component of the composition of the present invention, is prepared by combining a vinyl chloride resin and a plasticizer at a temperature below the melting temperature of the vinyl chloride resin, for example, below 130°C. Mix and heat to temperature
This is a powdered vinyl chloride resin containing a plasticizer and having an average particle size in the range of 30 to 300μ, which is obtained by absorbing the plasticizer into the vinyl chloride resin and then cooling it. The vinyl chloride resin used in the vinyl chloride resin composition A is a homopolymer of vinyl chloride or a copolymer of vinyl chloride and a monomer copolymerizable therewith, and has a large particle size and is porous. In order to improve the absorbability of plasticizers, it is usually produced by a suspension polymerization method or a bulk polymerization method, and preferably has an average degree of polymerization in the range of 400 to 11,200. Of course, depending on the particle size, it may be produced by fine suspension polymerization. Examples of monomers copolymerizable with vinyl chloride include ethylene, propylene, butene, pentene-1, butadiene,
Styrene, α-methylstyrene, acetic acid, caproic acid, caprylic acid, vinyl esters or aryl esters of carboxylic acids such as benzoic acid, dialkyl maleic acid or fumaric acid whose alkyl group has 1 to 12 carbon atoms (C1 to 12) Esters, acrylonitrile, vinylidene chloride, vinylidene cyanide, alkyl vinyl ethers with alkyl groups of C1 to 16, N-vinylpyrrolidone, vinylpyridine, vinylsilanes, acrylic acid alkyl esters or methacrylic acid alkyl esters of alkyl groups of C1 to 16 40 parts by weight or less of at least one of these per 100 parts by weight of vinyl chloride,
Preferably, copolymerization can be carried out in an amount of 30 parts by weight or less. If the average particle size is 300μ or more, the melting properties will deteriorate, requiring high temperature heating, and causing thermal deterioration. In addition, if the average particle size is smaller than 30μ, the difference in particle size with vinyl chloride resin B of 5μ or less will be small, and the flow characteristics of the powder will be poor, resulting in poor molding and processing.
Inconveniences are likely to occur during painting processing. The plasticizer contained in the vinyl chloride resin composition A is not particularly limited as long as it is used for vinyl chloride resins, but examples include di-n-butyl phthalate and di-n-octyl phthalate. , phthalic acid plasticizers such as di-2-ethylhexyl phthalate (DOP), diisooctyl phthalate, octyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl isophthalate, di-2 adipate -Ethylhexyl (DOA), di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl azelaate, dibutyl sebacate, di-2 sebacate
- Fatty acid ester plasticizers such as ethylhexyl,
Tributyl phosphate, tri-2-ethylhexyl phosphate, 2-ethylhexyldiphenyl phosphate,
Examples include phosphate ester plasticizers such as tricresyl phosphate, and one or more of these may be used in combination. Therefore, although the amount of plasticizer used varies depending on the degree of polymerization of the vinyl chloride resin, it needs to be at least 10 parts by weight per 100 parts by weight of the vinyl chloride resin, and generally speaking Within 100 parts by weight,
In particular, it is within 80 parts by weight. Of course, depending on the degree of polymerization of the vinyl chloride resin, it is possible to use 100 parts by weight or more. The most preferable relationship between the degree of polymerization of the vinyl chloride resin and the amount of plasticizer used is expressed by the following general formula. 10x+500≧y≧5x+400 [where y is the degree of polymerization of the vinyl chloride resin, x is the part by weight of the plasticizer used per 100 parts by weight of the vinyl chloride resin, and indicates a value of 10 or more. ] By setting it within this range, it is possible to melt at a particularly low temperature, and thermal deterioration can be completely prevented. Furthermore, other additives such as stabilizers, colorants, fillers, secondary plasticizers, etc. may be added to the above-mentioned vinyl chloride resin composition A within a range that does not adversely affect powder molding. Powdered vinyl chloride resin composition B containing a plasticizer and having an average particle size of 5μ or less used in the composition of the present invention is
For example, vinyl chloride alone or a mixture of vinyl chloride and the monomers mentioned above that can be copolymerized with it are pre-emulsified with deionized water, an oil-soluble polymerization initiator, an emulsifier, a plasticizer, etc. using an emulsifying machine such as a homogenizer. Latexes obtained by the so-called fine suspension polymerization method, in which polymerization is carried out after polymerization, or those produced by spray-drying latexes obtained by emulsion polymerization in the presence of a plasticizer by a conventional method, and Vinyl chloride resin produced by turbid polymerization, bulk polymerization, emulsion polymerization, fine suspension polymerization, etc. is kneaded with a plasticizer or gelled after preparing a paste, and the resulting composition is crushed and then classified. etc. are used. The plasticizer contained in the vinyl chloride resin composition B is preferably in the range of 5 to 60 parts by weight per 100 parts by weight of the resin component, particularly 1/4 to 1/4 of the amount of plasticizer contained in the vinyl chloride resin composition A. It is most preferable to set the range to about 3/4. When the amount of plasticizer is less than 1/4, the melting properties tend to worsen, causing burns (thermal deterioration), and when it is more than 3/4, it becomes difficult to fully exhibit the fluidity characteristics. In addition, of course, the vinyl chloride resin composition B may contain a stabilizer, to the extent that it does not adversely affect the production or powder molding process of the composition.
Other additives such as colorants, fillers and secondary plasticizers may also be added. The vinyl chloride resin composition for powder molding of the present invention is
Vinyl chloride resin composition A and vinyl chloride resin composition B are uniformly mixed without applying heat. The mixing ratio of both compositions is preferably such that the ratio of the former to the latter is in the range of 98/2 to 40/60 by weight; if the ratio is 98/2 or more, the melting characteristics and flow characteristics are likely to be insufficient. , and when the ratio is less than 40/60, the flow characteristics become poor. Since the vinyl chloride resin composition for powder molding of the present invention melts at a relatively low temperature, molding is easy and the powder has excellent flow characteristics.
Therefore, the composition of the present invention can be effectively used in various molding methods and coating methods such as rotational molding, powder coating, fluidized dip coating, and electrostatic coating, and its industrial utility value is extremely high. The composition of the present invention will be explained in detail below using Reference Examples and Examples, but the present invention is not limited to the following Examples unless it departs from the gist thereof. Manufacturing method of vinyl chloride resin composition B: Reference example 1 100 parts by weight of vinyl chloride monomer, 200 parts by weight of deionized water, 1 part by weight of lauryl peroxide, 20 parts by weight of diisodecyl phthalate, 1 part by weight of sodium lauryl sulfate, lauryl After pre-emulsifying a mixture of 0.7 parts by weight of alcohol using a homogenizer, it was put into a vacuum autoclave and 58
The polymerization reaction was carried out at ℃ for 8 hours. After collecting unreacted monomers, the resulting latex was spray dried to obtain an average polymerization degree of 980 containing 20 parts by weight of plasticizer.
A vinyl chloride resin composition B having an average primary particle diameter of 1 μm was obtained. Reference Examples 2 and 3 In Reference Example 1, 10 parts by weight (Reference Example 2) and 50 parts by weight (Reference Example 3) of dioctyl phthalate (DOP) were used instead of 20 parts by weight of diisodecyl phthalate (DIDP). Composition B was produced in the same manner as in Reference Example 1. Example A plasticizer (PLS) and Using a ribbon blender with the addition of Parts by Weight (PHR) of stabilizer
The mixture was heated and mixed at 110° C. for 1 hour to absorb the plasticizer into the vinyl chloride resin, and then cooled to room temperature to produce a powdered vinyl chloride resin composition A. A predetermined weight of Composition B produced in Reference Example was added to Composition A to prepare a vinyl chloride resin composition for powder molding so that Composition B had the weight percentage shown in Table 1. The appearance and bulk specific gravity of this composition were examined for powder flow characteristics, and the composition was coated on an iron plate to a thickness of 0.4 mm, transferred to a temperature-controlled heating furnace, and sintered for 3 minutes. The obtained film had a smooth surface, high elongation, and excellent melting properties. In addition, from the results in Table 1, it can be seen that it melts at an extremely low temperature,
It can be seen that larger values indicate elongation.

[Table] Comparative Example For comparison, the vinyl chloride resin compositions shown in Table 2 were tested in the same manner as in the Examples and are listed in Table 2.

【table】

Claims (1)

[Claims] 1 Powdered vinyl chloride resin composition A with an average particle diameter of 30 to 300 μ obtained by heating and mixing a vinyl chloride resin and a plasticizer to absorb the plasticizer into the vinyl chloride resin and then cooling the mixture, and a plasticizer. Powdered vinyl chloride resin composition B with an average particle diameter of 5μ or less,
A vinyl chloride resin composition for powder molding that is mixed without heating.