JPS6354018B2 - - 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 fusion, and 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 have stability that does not 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 plasticizers are added to improve the melting characteristics. I'm trying. and,
The lower the degree of polymerization of vinyl chloride resin, the better the melting properties tend to be. If the plasticizer concentration is too high, the powder will have poor fluidity. 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. 13727/1987 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: 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 vinyl chloride resin composition for powder molding that does not cause thermal deterioration and has excellent powder flow characteristics and melting characteristics. By incorporating a plasticizer into the small particle size vinyl chloride resin to be blended, the powder flow characteristics remain unchanged, and even at low melting temperatures, it has good melting characteristics and does not suffer from thermal deterioration. Heading: 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 that is mainly used for powder molding and has good powder flow characteristics and melting characteristics. Average particle size 30~ obtained by absorbing into vinyl resin and cooling to below 70℃
300μ of vinyl chloride resin composition A and (a) a mixture of vinyl chloride or vinyl chloride and a monomer copolymerizable therewith in the presence of a plasticizer are reacted by an emulsion polymerization method or a fine suspension polymerization method. The resulting vinyl chloride resin composition B or (b) a latex obtained by reacting vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith by an emulsion polymerization method or a fine suspension polymerization method in the presence of a plasticizer. This can be achieved with a vinyl chloride resin composition characterized in that at least one of the vinyl chloride resin compositions C obtained by heat treatment is mixed at a temperature of 70° C. or lower. 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
Average particle size of 30~ obtained by absorbing plasticizer into vinyl chloride resin and then cooling to a temperature of 70℃ or less
It is a powdered vinyl chloride resin containing a plasticizer with a size in the 300μ range. 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 a porous structure. It is usually manufactured by suspension polymerization method or bulk polymerization method in order to improve the absorption of plasticizer.
A range of 400 to 1500, especially a range of 500 to 1200 is preferred. 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, pentyne-1, butadiene, styrene, α-methylstyrene, acetic acid, caproic acid, caprylic acid, benzoic acid, etc., vinyl esters or aryl esters of carboxylic acids, alkyl groups with 1 to 12 carbon atoms (C _{1 to 12} ) dialkyl maleic or fumaric acid esters, acrylonitrile, vinylidene chloride, vinylidene cyanide, alkyl vinyl ethers of alkyl groups C _{1 to 16} , N-vinylpyrrolidone, vinylipyridine, vinylsilanes, alkyl groups C _{1 to 16} Examples include acrylic acid alkyl esters and methacrylic acid alkyl esters, and at least one of these can be copolymerized in an amount of 40 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of vinyl chloride. If the average particle size is 300μ or more, the melting properties will deteriorate, requiring high temperature heating, and causing thermal deterioration. In addition, when the average particle size is smaller than 30μ, the difference in particle size from vinyl chloride resin composition B or vinyl chloride resin composition C produced by emulsion polymerization method or fine suspension polymerization method becomes small, and the powder It has poor flow characteristics and tends to cause problems during molding and painting. 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 is preferably at least 10 parts by weight, and generally 100 parts by weight. Within,
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 [In the formula, 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 shows 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, 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. The vinyl chloride resin composition B used in the composition of the present invention is prepared by adding, for example, vinyl chloride alone or a mixture of vinyl chloride and the above-mentioned monomers copolymerizable therewith with deionized water and oil in the presence of a plasticizer. A latex obtained by the so-called fine suspension polymerization method, in which a soluble polymerization initiator, an emulsifier, etc. are pre-emulsified using an emulsifying machine such as a homogenizer, and then polymerized, or a latex obtained by a conventional emulsion polymerization method in the presence of a plasticizer. The latex thus obtained may be spray-dried as is, or may be coagulated by adding a flocculant or slightly heated to separate water and then dried in a conventional dryer such as a tray dryer. is used. As the flocculant, a water-soluble cationic polymer compound having a nitrogen atom in its molecular chain, a salting-out agent such as calcium chloride, etc. are used. The agglomerated and dried product produced by the latter method has an average particle size of 500 μm or less, and is extremely gently agglomerated. It is easily made into fine particles by Furthermore, the vinyl chloride resin composition C is a latex obtained by reacting vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith by an emulsion polymerization method or a fine suspension polymerization method. The plasticizer is absorbed into the vinyl chloride resin by heat treatment in the presence of the resin, a salting-out agent is added as needed, water is separated, and the resin is dried. If the particles are large and hard, it is desirable to use them after pulverizing them. Calcium chloride, magnesium chloride, etc. are used as the salting-out agent. Therefore, the average particle size of the vinyl chloride resin composition B or composition C is preferably 5μ or less when used in the composition of the present invention, and particles having a large particle size and hard It is desirable to classify and remove those having the following properties before use. The plasticizer contained in Composition B and Composition C is preferably in the range of 5 to 60 parts by weight based on 100 parts by weight of the resin component, and in particular, the amount of plasticizer contained in PVC resin composition A is preferably 5 to 60 parts by weight. It is most preferable to keep it in the range of about 1/4 to 3/4. If the amount of plasticizer is less than 1/4, the melting characteristics tend to deteriorate, resulting in discoloration (thermal deterioration).
If it exceeds 3/4, it becomes difficult to fully demonstrate the fluidity characteristics. Of course, vinyl chloride resin composition B or composition C may contain other additives such as stabilizers, colorants, fillers, secondary plasticizers, etc., to the extent that they do not adversely affect the production or powder molding process of these compositions. Additives may also be added. The vinyl chloride resin composition of the present invention is obtained by uniformly mixing vinyl chloride resin composition A and vinyl chloride resin composition B or vinyl chloride resin composition C at a temperature of 70°C or lower. Vinyl chloride resin composition B
and Composition C may be used together. The dried agglomerated product of Composition B or Composition C is added to Composition A and pulverized while stirring. The mixing ratio of Composition A and Composition B or Composition C is preferably such that the ratio of the former to the latter two is in the range of 98/2 to 40/60 by weight, and if the ratio is 98/2 or more, The melting properties and flow properties tend to be insufficient, and if the ratio is 40/60 or less, the flow properties become poor. According to the vinyl chloride resin composition of the present invention, since it melts at a relatively low temperature, it is easy to mold and process, 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 in reference examples and examples below, but the present invention is not limited to the following reference examples and examples unless it deviates from the gist thereof. Reference example Manufacturing method of vinyl chloride resin composition B: (1) Composition 100 parts by weight of vinyl chloride monomer, 200 parts by weight of deionized water
parts by weight, 1.5 parts by weight of lauryl peroxide,
A mixture of 8 parts by weight of dioctyl phthalate (DOP), 1 part by weight of sodium lauryl sulfate, and 0.7 parts by weight of lauryl alcohol was emulsified and finely dispersed using a homogenizer, and then placed in an autoclave under reduced pressure and heated at 53°C for 8 hours. A time polymerization reaction was carried out. After collecting the unreacted monomers, 0.5 parts by weight of calcium chloride is added to the latex to coagulate the vinyl chloride resin, followed by dehydration and drying to obtain a vinyl chloride resin composition containing 10 parts by weight of a plasticizer. Ta. The composition was easily turned into fine powder by fingertip pressure, and the degree of polymerization of the vinyl chloride resin therein was 1250. (2) Composition A composition was obtained by spray drying the latex obtained in the process of manufacturing the composition. Manufacturing method of vinyl chloride resin composition C: (3) Composition 100 parts by weight of vinyl chloride monomer, 200 parts by weight of deionized water
parts by weight, 0.3 parts by weight of sodium lauryl sulfate,
0.7 parts by weight of potassium persulfate was added to an autoclave under reduced pressure, and a polymerization reaction was carried out at 58°C for 8 hours. After collecting unreacted monomers, 35 parts by weight of DOP and 0.3 parts of calcium chloride were added to the latex.
Parts by weight were added and heat treated at 90° C. for 1 hour with stirring to cause the vinyl chloride resin to absorb the plasticizer and coagulate, and then dehydrated and dried to obtain a composition. The content of plasticizer in the composition was 40 parts by weight, and it was easily pulverized by fingertip pressure. Furthermore, the average degree of polymerization () of the vinyl chloride resin was 1050. (4) Composition A composition was obtained in the same manner as in the method for producing the composition, except that 35 parts by weight of DOP was replaced with 15 parts by weight of isodecyl phthalate (DIDP). The plasticizer content of the composition is 17
The weight part was 1050 for the resin. Example A predetermined part by weight of a plasticizer is added to 100 parts by weight of a vinyl chloride resin (PVC) produced by a suspension polymerization method or a fine suspension polymerization method having a specific average degree of polymerization () and average particle size shown in Table 1. (PHR) and 1 part by weight of dibutyltin maleate were mixed with high speed stirring using a Henschel mixer until the resin temperature reached 120°C.
When the temperature reached 120°C, water was passed through the jacket part of a Henschel mixer and cooled while mixing at low speed to produce vinyl chloride resin composition A. When the composition A reached the temperature listed in Table 1, composition B or composition C produced in the reference example was added so that a specific amount (wt%) of the composition was contained in the final composition, and the mixture was further stirred at a low speed. Cooling was continued while stirring, and when the resin temperature reached 40°C, stirring and cooling was stopped and the vinyl chloride resin composition was taken out. In the composition, Composition B or C was pulverized and became a primary particle or a state close to it. The powder flow characteristics of this composition were examined by its appearance and bulk specific gravity, 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 there is a large increase.

[Table] Comparative Example Compositions other than the present invention were investigated in the same manner as in the examples under conditions and methods similar to those in the examples, and the results are shown in Table 2.

【table】

[Table] As shown in the comparative examples, ordinary powder molding resins (Comparative Examples 1 and 2) have inferior powder flow characteristics and melting characteristics compared to the composition of the present invention. It is clear. In addition, products containing ordinary emulsion polymerized products (Comparative Examples 3 and 4) have good fluidity, but have poor melting properties, and in order to improve melting properties, it is necessary to increase the heating temperature, and heat treatment is required. It is the cause of deterioration.

Claims (1)

[Claims] 1 Heat mix the vinyl chloride resin and plasticizer to absorb the plasticizer into the vinyl chloride resin, then heat to 70°C.
Emulsify vinyl chloride resin composition A with an average particle size of 30 to 300μ obtained by cooling as follows, and (a) a mixture of vinyl chloride or a monomer copolymerizable with vinyl chloride and vinyl chloride in the presence of a plasticizer. Vinyl chloride resin composition B obtained by reacting by a polymerization method or a fine suspension polymerization method or (b) vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith is subjected to an emulsion polymerization method or a fine suspension polymerization method. A vinyl chloride resin composition, characterized in that at least one of the vinyl chloride resin compositions C obtained by heat-treating legally reacted latex in the presence of a plasticizer is mixed at a temperature of 70° C. or lower.