JPS6354019B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides powder molding that makes it possible to produce a powder molded product that does not undergo thermal deterioration, has excellent powder fluidity and meltability during molding or painting, and has excellent surface smoothness or matte property. The present invention relates to a resin composition for use. 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, as well as to ensure the smoothness and gloss of the surface of the resulting molded product. Recently, the number of cases requiring erasability has been increasing. The purpose of this is to give a luxurious feel that does not resemble plastic when used in automobile interior materials, etc., and has become an important element in the recent interior materials market that is oriented toward luxury products. In the present invention, the surface smoothness of a molded article refers to a state in which there are no irregularities such as pockmarks that occur on the side that does not come into contact with a mold, etc., and matteness refers to a state in which there are no microscopic irregularities on the entire surface. This refers to a state that is smooth and lacks luster when viewed as a whole. The present inventors have previously developed a vinyl chloride resin composition containing a plasticizer as a powder molding vinyl chloride resin composition that has excellent powder fluidity and melting properties and is free from thermal deterioration during processing. and plasticizers.
Patent application No. 57-176764 for a composition obtained by mixing a powdered vinyl chloride resin composition with a particle size of 5μ or less without heating.
proposed as a number. With the composition of the invention, a powder compact with excellent powder flowability, meltability, or surface smoothness can be obtained, but the surface smoothness of the side not in contact with the mold is not sufficient and is extremely poor. Only glossy molded products can be obtained. If this composition is subjected to powder molding and molded at a low temperature in an attempt to forcibly remove the luster, a certain degree of matteness can be achieved, but the physical properties such as mechanical strength of the molded product deteriorate, making it very difficult to use for practical use. do not have. As a result of intensive study to produce a matte-like powder molded body without deterioration of physical properties such as mechanical strength of the molded body, the present inventors determined that the surface area of the vinyl chloride resin that has absorbed the plasticizer can be It has been discovered that by covering 90% or more of a thermoplastic emulsion polymer, a matte molded product can be obtained without deteriorating the powder fluidity, melting properties, and mechanical properties of the molded product, and the coating The inventors have discovered that even when the ratio is less than 90%, a molded article with excellent powder flowability, melting characteristics, and surface smoothness can be obtained, and the present invention has been achieved. That is, an object of the present invention is to produce a molded product that has excellent powder flowability, melting characteristics, and thermal stability during powder molding, and has a smooth or matte surface without reducing mechanical strength. The present invention provides a resin composition for powder molding. The gist of the present invention is therefore a resin composition for powder molding, which is formed by coating a thermoplastic emulsion polymer on a vinyl chloride resin that has absorbed a plasticizer, wherein the plasticizer is a vinyl chloride resin that has absorbed a plasticizer. 700 (1+X/100)≧Y≧250 (1+X/100) [wherein, X is vinyl chloride resin 100] It is the weight part of the plasticizer per weight part, and the value is 10 or more, and Y indicates the viscosity average degree of polymerization of the vinyl chloride resin. ] The thermoplastic emulsion polymer has an average particle diameter of 0.01
Uses at least one of ~1 μm vinyl chloride emulsion polymer, methyl methacrylate emulsion polymer, or styrene-acrylonitrile emulsion copolymer (acrylonitrile content in the range of 20 to 40% by weight), and absorbs a plasticizer. The present invention provides a resin composition for powder molding, characterized in that the surface area of the vinyl chloride resin covered by the thermoplastic emulsion polymer is at least 5%. To explain the present invention in detail, the vinyl chloride resin that has absorbed a plasticizer, which is one of the components of the composition of the present invention, means, for example, that the vinyl chloride resin and the plasticizer are mixed at a temperature lower than the melting temperature of the vinyl chloride resin. ,in particular
Powdered vinyl chloride resin obtained by heating and mixing at a temperature of 130°C or lower to absorb the plasticizer into the vinyl chloride resin, followed by cooling. The vinyl chloride resin is a homopolymer of vinyl chloride or a copolymer of vinyl chloride and a monomer copolymerizable therewith,
In order to increase the particle size and make it porous to improve plasticizer absorption, it is usually produced by suspension polymerization or bulk polymerization. Preferably, it is manufactured. Examples of monomers copolymerizable with vinyl chloride include vinyl carboxylic acids such as ethylene, propylene, butene, pentene-1, butadiene, styrene, α-methylstyrene, acetic acid, caproic acid, caprylic acid, and benzoic acid. Esters or aryl esters, alkyl group having 1 to 12 carbon atoms
( _C1-12 ) dialkyl maleic or fumaric acid esters, acrylonitrile, vinylidene chloride, vinylidene cyanide, alkyl vinyl ethers with alkyl groups _C1-16 , N-vinylpyrrolidone, vinylipyridine, vinylsilanes, alkyl groups _{C1-16 16} acrylic acid alkyl esters or 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. . The degree of polymerization of these vinyl chloride resins to be selected is determined by the type and amount of the plasticizer used. The preferred 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,
respectively indicate the viscosity average degree of polymerization of vinyl chloride resin. ] The amount of plasticizer used is limited depending on the degree of polymerization of the vinyl chloride resin when the amount of plasticizer used is greater than the amount specified above for the desired plasticizer, amount, and formulation. This is because the fluidity of the powder deteriorates significantly and the plasticizer bleeds out from the molded product, making it impossible to put it to practical use. On the other hand, if an amount smaller than the specified amount is used, the physical properties will be inferior due to processing temperature restrictions. The amount of plasticizer to be used is generally such that the degree of polymerization and plasticizer are within the above-mentioned relationship range, and most preferably in the range of 30 to 150 parts by weight of plasticizer per 100 parts by weight of vinyl chloride resin. The plasticizer that can be absorbed into the vinyl chloride resin is not particularly limited as long as it is used for the vinyl chloride resin, but dialkyl phthalates, dialkyl adipates, and trialkyl tricarbons having an alkyl group having 4 to 13 carbon atoms can be used. Examples include mellitate, dialkyl sebacate, dialkyl azelate, alkyl benzyl phthalate, trialkyl phosphate, alkyl allyl phosphate, and polyester plasticizers. Specifically, di-n-butyl phthalate, phthalic acid G-n-
Octyl, di-2-ethylhexyl phthalate (DOP), diisooctyl phthalate, octyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl isophthalate, di-2-ethylhexyl adipate (DOA), Di-n-decyl adipate, diisodecyl adipate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl azelaate, dibutyl sebacate, di-2-sebacate
Examples include ethylhexyl, tributyl phosphate, tri-2-ethylhexyl phosphate, 2-ethylhexyldiphenyl phosphate, and tricresyl phosphate, and these may be used alone or in combination of two or more. In addition, other additives such as stabilizers, colorants, fillers, secondary plasticizers, etc. may be added to the vinyl chloride resin that has absorbed the above-mentioned plasticizer to the extent that they do not adversely affect powder molding. You can leave it there. Thermoplastic emulsion polymers used to coat the surface of vinyl chloride resins that have absorbed plasticizers include vinyl chloride emulsion polymers, methyl methacrylate emulsion polymers, and styrene-acrylonitrile emulsion copolymers (acrylonitrile content: 20-40%, preferably 25-35%). This emulsion polymer preferably has a primary average particle diameter in the range of 0.05 to 1 μm,
It is preferably in the range of 0.05 to 0.5 μm, particularly 0.05 to 0.3 μm. If the particle size is smaller than 0.05 μm, fluidity is not good. On the other hand, if the particle size is larger than 1 μm, a molded product with good surface smoothness cannot be obtained, and the physical properties of the molded product will be poor. These emulsion polymers are made by emulsifying the main monomer of the emulsion polymer with a monomer copolymerizable with it, within a range that does not adversely affect the production of the resin composition for powder molding or the powder molding process. It may be a copolymer, and other additives such as stabilizers, colorants, fillers or plasticizers may be added. These emulsion polymers are composed of vinyl chloride monomers, methyl methacrylate monomers, styrene to acrylonitrile monomer mixtures, or monomers that are copolymerizable with these monomers. A conventional emulsion polymerization method in which a monomer mixture is reacted with deionized water, an emulsifier, and a water-soluble polymerization initiator;
Alternatively, the above single monomer or monomer mixture is emulsified with deionized water, an emulsifier, and an oil-soluble polymerization initiator, and the resulting latex is spray-dried or salted out and agglomerated. It is manufactured by a normal drying method such as dehydration and drying after drying. The amount of copolymerizable monomer used is
It is preferably as small as possible, and generally 20% or less of the total monomers. The surface of the vinyl chloride resin that has absorbed the plasticizer of these emulsion polymers is coated with the vinyl chloride resin that has absorbed the plasticizer using a Henschel mixer, ribbon blender, crusher, etc. This is very easily achieved by simply mixing the emulsion polymers. The coverage rate depends on the type of vinyl chloride resin used to absorb the plasticizer, the type and amount of the emulsion polymer,
Although it varies depending on the type of mixer, mixing time, etc., it can be easily determined by conducting some preliminary experiments. For example, in order to obtain a powder molded body with excellent powder flow characteristics, melting characteristics, and thermal stability, and with excellent surface smoothness, a thermoplastic emulsion polymer of vinyl chloride resin that has absorbed a plasticizer is used. It is preferable that the coverage is 5% or more and less than 90%, preferably in the range of 8 to 80%, and in order to achieve this coverage, a vinyl chloride resin and a thermoplastic emulsion polymer that have absorbed a plasticizer are used. It is generally desirable that the mixing ratio of the former/latter be in the range of 99/1 to 60/40 by weight. In addition, for the purpose of producing a powder molded body that has excellent powder flow characteristics, melting characteristics, and thermal stability and has a matte surface, it is preferable that the coverage is 90% or more. Generally speaking, the mixing ratio of vinyl chloride resin that has absorbed plasticizer to thermoplastic emulsion polymer is the former/latter in terms of weight ratio.
A range of 95/5 to 55/45 is sufficient, and even if an emulsion polymer exceeding this range is used, the matting effect will not be improved more than necessary, resulting in an economic disadvantage. If the coverage is less than 90%, it will be difficult to achieve a matting effect. The powder molding resin composition of the present invention itself has excellent powder flow characteristics, and since it melts at a relatively low temperature, it can be easily molded and has excellent thermal stability. Furthermore, when the composition of the present invention is subjected to various powder molding methods, whether a molded product with a smooth surface on the side not in contact with a mold etc. can be obtained due to the difference in coverage with the emulsion polymer; There is a difference in whether a molded product with a matte surface or a molded product with a matte surface can be obtained, and a wide variety of powder molded products can be manufactured. 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 described 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. Raw material production example 1 Method for producing thermoplastic emulsion polymers [] to [] In a 3-volume stainless steel autoclave, add 200 parts by weight of deionized water, sodium lauryl sulfate (parts by weight shown in Table 1), and 0.8 parts by weight of potassium persulfate. After replacing the inside of the autoclave with nitrogen, 100 parts by weight of vinyl chloride monomer was added and heated to 58°C.
The mixture was allowed to react for 8 hours. After removing unreacted residual monomers, the resulting latex was freeze-dried to obtain a vinyl chloride emulsion polymer having the primary average particle diameter shown in Table 1.

[Table] Raw material production example 2 Production method of thermoplastic emulsion polymer [ ] In a 3-volume stainless steel autoclave, add 200 parts by weight of deionized water, 1 part by weight of sodium lauryl sulfate, 0.5 part by weight of potassium persulfate, and 100 parts by weight of methyl methacrylate. After replacing the gas phase with nitrogen, the temperature was raised to 70°C and the reaction was allowed to proceed for 5 hours. After removing unreacted residual monomers, the obtained latex was spray dried to obtain a methyl methacrylate emulsion polymer. The primary average particle diameter was 0.1 μm. Raw material production example 3 Method for producing thermoplastic emulsion polymers [] to [] In a 3-volume stainless steel autoclave, add 100 parts by weight of the total monomer mixture of styrene and acrylonitrile in the proportions shown in Table 2. 20 parts by weight of the solution, 200 parts by weight of deionized water, 1 part by weight of sodium lauryl sulfate, and 0.5 parts by weight of potassium persulfate were added, and after replacing the gas phase with nitrogen, the temperature was raised to 80°C to start the reaction. During the reaction, 80 parts by weight of the remaining monomer mixture were successively added over 2 hours, and after the addition was completed, the reaction was allowed to proceed for 3 hours to produce a latex of a styrene-acrylonitrile emulsion copolymer. The latex was spray-dried to obtain an emulsion polymer having an acrylonitrile content and an average primary particle diameter as shown in Table 2.

[Table] Note that the primary average particle diameter was measured by electron microscopy observation. Examples 1 to 7, Comparative Examples 1 to 4 100 parts by weight of vinyl chloride straight polymer (suspension polymer) with viscosity average degree of polymerization of 800, 1 part by weight of mercaptotin stabilizer, 80 parts by weight of di-2-ethylhexyl phthalate. was put into a Henschel mixer, and the temperature was raised while stirring and mixing. Stirring was continued until the resin temperature rose to 130°C, so that the plasticizer was absorbed into the vinyl chloride straight polymer. Cool the polymer while stirring, and when the resin temperature of the polymer reaches 60°C, add the emulsion polymer shown in Table 3 to the polymer at a predetermined ratio, and continue mixing for the time shown in Table 3. did. In the composition thus prepared, the surface of the vinyl chloride resin that has absorbed the plasticizer is coated with the emulsion polymer at a coverage ratio shown in Table 3. Table 3 shows the evaluation results when these resin compositions were subjected to powder molding. It can be seen that a powder molded body with good physical properties and a good matte state can only be obtained when a methyl methacrylate emulsion polymer or a styrene-acrylonitrile emulsion copolymer is used. In addition, the characteristics of the resin composition for powder molding and the physical properties of the molded article in the Examples were measured as follows. (1) Measurement of coverage was carried out by observation of electron micrographs. In order to calculate the coverage rate, it is necessary to calculate the surface area of the particle and the area of the covered part. When photographing spherical particles, it is difficult to fairly evaluate the surface area of slanted parts, so we also express the coverage ratio of parts that can be considered to be approximately horizontal. For example, in the case of a photograph of a spherical particle, assuming that the radius of the particle on the plane is R, the coverage of a portion surrounded by a diameter of 1/3R from the center was determined. The method provides extremely accurate coverage. (2) Powder fluidity 100 ml of the composition was put into a hopper for a bulk density measuring device according to JIS K 6721, and the fluidity was judged based on the time (seconds) for the entire amount of the composition to fall from the hopper. (3) Elongation The powder molding composition was coated on aluminum foil to a thickness of 1 mm and sintered for 10 minutes in an oven controlled at 200℃.The resulting film was rated according to JIS standards.
Measured by K 6723. (4) Matte state The film obtained in item (3) was visually evaluated on a five-point scale. Grade 5 (good matte) - Grade 1 (poor).

【table】

[Table] Example 8, Comparative Examples 5 to 6 100 parts by weight of the vinyl chloride resin shown in Table 4 (both suspension polymerization and straight polymer), 120 parts by weight of diisodecyl phthalate, and 1 part by weight of tin-based stabilizer were added to 110 parts by weight. The mixture was heated and mixed for 1 hour using a ribbon blender kept at a temperature of 0.degree. C. to absorb the plasticizer. PVC resin and emulsion polymer []85/15
(weight ratio) and kneaded and mixed for 20 minutes using a crusher to obtain a vinyl chloride resin composition for powder molding having a coverage rate of the emulsion polymer shown in Table 4. A powder compact was produced from the composition in the same manner as in Example 1. The powder characteristics of the composition and the evaluation results of the molded body are also listed in Table 4.
It can be seen that excellent results were obtained when a vinyl chloride resin having a degree of polymerization within the range of X/100)≧Y≧250 (1+X/100) was used.

[Table] Examples 9 to 17, Comparative Examples 7 to 10 Powder molding resin compositions with different coverage rates were produced by the same method as in Example 1, and the characteristics of the compositions and the surface of powder molded bodies were The smoothness was measured and recorded in Table 5. The meltability, surface smoothness and thermal stability were measured by the following methods. (4) Meltability A resin composition for powder molding was coated on aluminum foil to a thickness of 1 mm, heated at 180°C, and evaluated based on the time it took to form a transparent film. (5) Surface smoothness The resin composition for powder molding was coated on aluminum foil to a thickness of 2 mm and sintered for 3 minutes in an oven controlled at 200°C. The degree of unevenness was examined using a measuring machine. It is expressed as the difference between the maximum thickness of the convex portion and the minimum thickness of the concave portion. (6) Thermal stability The transparent film produced in item (4) was heated in a gear oven at 220°C, and the evaluation was based on the time it took for the film to change color.

[Table] Example 18, Comparative Examples 11-12 A resin composition for powder molding with a coverage of less than 90% was prepared using the vinyl chloride resin used in Example 8 and Comparative Examples 5 and 6 in the same manner as in Example 8. manufactured and measured the powder fluidity, meltability, thermal stability, and surface smoothness of the molded product,
It is shown in Table 6. As a result, 700(1+X/100)≧Y≧250(1+X/1
It can be seen that when a vinyl chloride resin having a degree of polymerization outside the range of 00) is used, the surface smoothness is poor.

[Table] Examples 19 to 21 Using the same method as in Example 1, the surface of vinyl chloride resin that had absorbed a plasticizer was coated with the thermoplastic emulsion polymer shown in Table 7, with a coverage rate of 40% in each case. It was coated so that Table 7 also lists the powder properties and molded body evaluation results of these compositions.

【table】

Claims (1)

[Scope of Claims] 1. A resin composition for powder molding comprising a vinyl chloride resin that has absorbed a plasticizer and coated with a thermoplastic emulsion polymer, wherein the plasticizer has a viscosity of the vinyl chloride resin. Using the amount of X expressed in the range of the following general formula between the average degree of polymerization Y, 700 (1 + X / 100) ≧ Y ≧ 250 (1 + X / 100) [wherein, It is the weight part of the plasticizer per unit, and the value is 10 or more, and Y indicates the viscosity average degree of polymerization of the vinyl chloride resin. ] The thermoplastic emulsion polymer has an average particle size of 0.05
Uses at least one of ~1 μm vinyl chloride emulsion polymer, methyl methacrylate emulsion polymer, or styrene-acrylonitrile emulsion copolymer (acrylonitrile content in the range of 20 to 40% by weight), and absorbs a plasticizer. A resin composition for powder molding, characterized in that the surface area of the vinyl chloride resin covered by the thermoplastic emulsion polymer is at least 5%. 2. The resin composition for powder molding according to claim 1, which makes it possible to produce a powder molded body with a smooth surface and a coverage of 5% or more and less than 90%. 3. The resin composition for powder molding according to claim 1, which makes it possible to produce a matte powder molded body having a coverage of 90% or more.