JPH0352496B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a vinyl chloride resin composition for powder molding that enables the production of powder molded products that do not cause thermal deterioration, have excellent powder fluidity and meltability during molding or painting, and have excellent surface smoothness. Pertaining to things. 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 painting methods are required to have excellent powder flow characteristics, melting properties, and stability that does not cause thermal deterioration during heating, and the resulting molded products must have excellent surface smoothness. What is there is desired. However, the synthetic resins used in 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. The present inventors first created a resin composition for powder molding that has excellent powder fluidity and melting properties and does not undergo heat deterioration during processing, and has an average particle size of 30 to 300 μm obtained by incorporating a plasticizer and then cooling it. Patent Application No. 57-176764 proposed a composition in which a powdered vinyl chloride resin composition containing a powdered vinyl chloride resin composition and a plasticizer and having an average particle diameter of 5μ or less were mixed without heating. . The composition of the invention has good powder fluidity and meltability, and shows no thermal deterioration during processing, and in this sense is an excellent resin composition for powder molding. However, the surface smoothness of the molded product obtained from this composition on the side not in contact with the mold was not sufficient. In order to improve the surface smoothness of a molded product, it is sufficient to set the heating conditions during heating and melting to extremely high temperatures, but unlike other polymeric compounds such as olefins, polyvinyl chloride It has the disadvantage of being easily discolored by heat, and such means cannot be adopted industrially. The inventors of the present invention further investigated the above-mentioned drawback, namely, to improve the surface smoothness of the side of the molded product that does not come into contact with the mold, and found that polyvinyl chloride containing a plasticizer and a material with a specific viscosity average A composition in which a polyvinyl chloride emulsion polymer having a specific degree of polymerization and a specific primary average particle size is mixed contributes to the smoothness of the surface of the molded product, and also improves the powder flow characteristics, meltability, and thermal properties of the composition itself. The present invention was achieved by discovering that it also has excellent stability. Polyvinyl chloride emulsion polymers are known to be used in the field of processing vinyl chloride resins, for molded products from plastisols or organosols, or for hard extrusion processing without the use of plasticizers. However, the resins used for these applications are those with a high viscosity average degree of polymerization in order to improve their mechanical properties, and polymers with a very low degree of polymerization, such as a viscosity average degree of polymerization of 300 to 900, have poor mechanical properties. When used for hard extrusion processing, the mechanical properties deteriorate and the desired effect of improving extrusion processability is insufficient.
No consideration has been given to the use of vinyl chloride emulsion polymers having such extremely low degrees of polymerization. The present invention improves powder flowability, meltability, and It has been discovered that it is possible to produce a resin composition that provides a powder molded article that has excellent thermal stability, mechanical properties, and surface smoothness. That is, an object of the present invention is to provide a vinyl chloride resin composition capable of producing a powder molded body that has excellent powder characteristics during powder molding and has a smooth surface on the side of the molded body that does not come into contact with a mold. is to provide. Therefore, the gist of the present invention is to provide a vinyl chloride resin with a plasticizer and a viscosity average degree of polymerization Y of the vinyl chloride resin in an amount of X expressed by the following general formula: 700 (1+X/100)≧Y ≧250 (1+X/100) [wherein, show. ] A powdered polyvinyl chloride composition obtained by heating and mixing for absorption and cooling, and a viscosity average degree of polymerization of 300 to 900 and a primary average particle size of 0.05 to 2 μm.
The present invention provides a vinyl chloride resin composition for powder molding, which is prepared by mixing a polyvinyl chloride emulsion polymer. To explain the present invention in detail, the polyvinyl chloride composition, 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
It is a powdered composition obtained by absorbing a plasticizer into a vinyl chloride resin and then cooling it. The vinyl chloride resin used in the polyvinyl chloride composition is a homopolymer of vinyl chloride or a copolymer of vinyl chloride and a monomer that can be copolymerized with it, and has a large particle size and a porous structure. In order to improve the absorbability of plasticizers, it is preferable that the polymer be manufactured by a suspension polymerization method or a bulk polymerization method. In addition, monomers that can be copolymerized with vinyl chloride include, for example, ethylene, propylene,
Butene, pentene-1, butadiene, styrene,
Vinyl esters or aryl esters of carboxylic acids such as α-methylstyrene, acetic acid, caproic acid, caprylic acid, benzoic acid, etc., dialkyl maleic acid or fumaric acid ester with an alkyl group having 1 to 12 carbon atoms (C _{1 to 12} ) , acrylonitrile,
Vinylidene chloride, vinylidene cyanide, alkyl vinyl ether with alkyl group _C1-16 , N-vinylpyrrolidone, vinylpyridine, vinylsilanes,
Examples include acrylic acid alkyl esters or methacrylic acid alkyl esters having an alkyl group of C _{1 to 16} , and at least one of these is combined with vinyl chloride 100
It can be copolymerized in an amount of 40 parts by weight or less, preferably 30 parts by weight or less. The degree of polymerization of suspension or bulk polymers to be selected as these vinyl chloride resins is determined by the amount of plasticizer used. 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. 700 (1+X/100)≧Y≧250 (1+X/100) [In the formula, The viscosity average degree of polymerization is shown respectively. ] The degree of polymerization of the polymer is limited by the amount of plasticizer used, if the desired plasticizer, amount used, and composition are used, the polymer has a degree of polymerization below the above-specified degree of polymerization. The fluidity of the powder deteriorates significantly,
In addition, the plasticizer bleeds from the molded product to a large extent, making it impossible to put it into practical use. On the other hand, if a polymer having a degree of polymerization higher than the specified value is used, the meltability and surface smoothness will be poor. Further, other additives such as stabilizers, colorants, fillers, secondary plasticizers, etc. may be added to the above-mentioned polyvinyl chloride composition within a range that does not adversely affect powder molding. The plasticizer contained in the polyvinyl chloride composition is not particularly limited as long as it is used for vinyl chloride resin, 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, 2-ethylhexyl azelaate, dibutyl sebacate, di-2-sebacate
Examples include fatty acid ester plasticizers such as ethylhexyl, phosphate ester plasticizers such as tributyl phosphate, tri-2-ethylhexyl phosphate, 2-ethylhexyldiphenyl phosphate, and tricresyl phosphate. Use a mixture of two or more types. The polyvinyl chloride emulsion polymer, which is the other component constituting the composition of the present invention, has a viscosity average polymerization degree of
300 to 900 and a primary average particle diameter of 0.05 to 2 μm, among which the average particle diameter is 0.05 μm.
~1 μm, preferably with an average degree of polymerization of 400 to 800,
400-700 is highly preferred. Average degree of polymerization
If less than 300 is used, disadvantages such as poor thermal stability and poor powder fluidity are likely to occur. Furthermore, if a number exceeding 900 is used, the surface smoothness of the resulting molded product tends to be poor. On the other hand, if particles with a primary average particle diameter of less than 0.05 μm are used, the fluidity of the powder will be poor. 2μ
This is because if particles exceeding m are used, the powder will not only have poor fluidity but also poor meltability and surface smoothness. Polyvinyl chloride-based emulsion polymers are produced by the usual emulsion polymerization method, that is, by initiating water-soluble polymerization using pure water, vinyl chloride monomer, or a mixture of vinyl chloride and the aforementioned monomers that can be copolymerized with it. or a method in which vinyl chloride alone or a mixture of vinyl chloride and the monomers mentioned above that can be copolymerized with it are polymerized in the presence of deionized water, an oil-soluble polymerization initiator, an emulsifier, a plasticizer, etc. It is produced by a method such as so-called fine suspension polymerization, in which the polymer is pre-emulsified using an emulsifying machine such as a homogenizer, and then polymerized. The average degree of polymerization is adjusted by a conventional method of adjusting dimensions, ie, reaction temperature, or by using a chain transfer agent. Even if other additives such as stabilizers, colorants, fillers, and plasticizers are added to the vinyl chloride emulsion polymer to the extent that they do not adversely affect the production or powder molding process of the polymer, good. The vinyl chloride resin composition for powder molding of the present invention is
This is a uniform mixture of a polyvinyl chloride composition and a polyvinyl chloride emulsion polymer. The mixing ratio of the composition and the emulsion polymer is preferably such that the ratio of the former to the latter is in the range of 98/2 to 60/40 by weight.
If the ratio exceeds 98/2, the flow characteristics tend to be insufficient, and if the ratio is less than 60/40, the flow characteristics and surface smoothness tend to deteriorate. 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.
Furthermore, the surface smoothness of the molded product obtained by the powder molding method is also extremely excellent. 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 raw material production examples and examples, but the present invention is not limited to the following examples unless it departs from the gist thereof. Production method of polyvinyl chloride emulsion polymer Raw material production example 1 100 parts by weight of vinyl chloride monomer (VCM), 200 parts by weight of deionized water, 1 part by weight of lauryl peroxide, 1 part by weight of sodium lauryl sulfate, 0.7 parts by weight of lauryl alcohol A mixture of trichlorethylene in the weight parts and amounts shown in Table 1 was emulsified using a homogenizer, then transferred to an autoclave under vacuum, and reacted at various reaction temperatures shown in Table 1 for 8 hours. After the completion of the reaction, the remaining vinyl chloride monomer was recovered, and the resulting latex was spray-dried.
Six types of emulsion polymers [A] to [F] having the viscosity average degree of polymerization and the average primary particle diameter shown in the following were obtained. The viscosity average degree of polymerization was measured according to JIS K6721. The primary average particle diameter was determined by electron microscopic observation. The primary average particle size means the weight average particle size of aggregated particles when they are not constituted, and the weight average particle size of the unit particles that constitute them when they constitute aggregated particles. Raw material production example 2 100 parts by weight of vinyl chloride monomer, 200 parts by weight of deionized water, 0.5 parts by weight of potassium persulfate, 1.5 parts by weight of trichloroethine, and the amount of sodium lauryl sulfate shown in Table 2 were put into an autoclave under vacuum. death
The reaction was carried out at 64°C. After the completion of the reaction, the remaining vinyl chloride monomer was collected, and the resulting latex was salted out and dehydrated to form emulsion polymers [G] to [I] having the viscosity average degree of polymerization and the average primary particle size shown in Table 2. Three types were manufactured. Raw material production example 3 Emulsion polymer [D] parts by weight, trichlorethylene
1.5 parts by weight, 100 parts by weight of vinyl chloride monomer, 200 parts by weight of deionized water, and 0.5 parts by weight of potassium persulfate were placed in an autoclave under vacuum, and 1 part by weight of sodium lauryl sulfate was added sequentially to prevent the formation of new particles. Polymerized quickly. The obtained latex was spray dried to form an emulsion polymer [J] as shown in Table 2.
I got it.

【table】

[Table] Examples 1 to 9, Comparative Examples 1 to 6 100 parts by weight of vinyl chloride resin (vinyl chloride homopolymer, suspension polymer product) with an average degree of polymerization of 720, 1 part by weight of mercaptotin stabilizer, phthalic acid G-2-
80 parts by weight of ethylhexyl was put into a ribbon blender, heated and mixed at 110° C. for 1 hour, and then cooled to room temperature to obtain a powdered polyvinyl chloride composition. The polyvinyl chloride emulsion polymers shown in Tables 1 and 2 were added thereto in the amounts shown in Table 3, and the mixture was further mixed for 30 minutes at room temperature to produce a vinyl chloride resin composition for powder molding. Table 3 shows the properties of the compositions and the surface smoothness of the molded products when these compositions were subjected to powder molding. These results show that it is only when a polyvinyl chloride emulsion polymer with an average degree of polymerization of 300 to 900 and an average primary particle diameter of 0.05 to 2 μm is used that it has excellent powder fluidity, meltability, surface smoothness, and thermal stability. You can see what you can get. Powder flowability was determined by putting 100 c.c. of a vinyl chloride resin composition for powder molding into a hopper for measuring bulk density (JIS K6721) and measuring the time until the entire amount fell from the hopper. Meltability was determined by coating the composition on an aluminum foil to a thickness of 1 mm, heating it to 180°C, and measuring the time taken to form a transparent film. Thermal stability was determined by heating the above-mentioned transparent film in a gear oven at 220°C and measuring the time until the film changed color. The surface smoothness of the molded product was determined by coating the composition on aluminum foil to a thickness of 2 mm, sintering it for 3 minutes in an oven controlled at 200°C, and applying the obtained sheet to a Kosaka type universal surface measuring machine. The degree of unevenness was investigated and expressed as the difference between the maximum thickness of the convex part and the minimum thickness of the concave part.

[Table] *2 Tap the hopper intermittently to remove it.
*3 Drop the hopper while hitting it.
Examples 10-11, Comparative Examples 7-8 100 parts by weight of vinyl chloride resin produced by suspension polymerization shown in Table 4, 120 parts by weight of dioctyl phthalate, and 1 part by weight of tin-based stabilizer were heated to 110°C. te1
The mixture was stirred and heated in a time crusher to absorb the plasticizer, and then cooled to obtain a powdered polyvinyl chloride composition. This composition and polyvinyl chloride emulsion polymer [I] were blended in a ratio of 85 parts by weight of the former and 15 parts by weight of the latter, and mixed without heating in a crusher for an additional 30 minutes to form a chloride for powder molding. A vinyl resin composition was produced. The properties of the powder molding composition and the smoothness of the molded body surface were measured and are also listed in Table 4.

[Table] When the degree of polymerization of the vinyl chloride resin is high, or when the amount of the polymer and plasticizer of the vinyl chloride resin is not within the range of the present invention, the powder flowability or surface smoothness may be poor, and the It turns out that it is unsuitable as a composition for powder molding, which is the object of the invention.

Claims (1)

[Scope of Claims] 1 A plasticizer is added to a vinyl chloride resin and the amount of X expressed in the range of the following general formula between the viscosity average degree of polymerization Y of the vinyl chloride resin is 700 (1+X/100)≧Y≧ 250 (1+X/100) [wherein, . ] A powdered polyvinyl chloride composition obtained by heating and mixing for absorption and cooling, and a viscosity average degree of polymerization of 300 to 900 and a primary average particle size of 0.05 to 2 μm.
A vinyl chloride resin composition for powder molding, which is obtained by mixing a polyvinyl chloride emulsion polymer of