JPH0564980B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a composition for vinyl chloride resin foam, and particularly to a composition for vinyl chloride resin foam that is excellent in processing operations. Vinyl chloride resin is inexpensive and has excellent physical and chemical properties, so it is widely used in various applications such as hard and soft fields and foams such as leather. In general, vinyl chloride resin foams are produced by heating a composition containing a vinyl chloride resin, a liquid plasticizer such as dioctyl phthalate, and a foaming agent to a high temperature to foam it. The foam has the advantages of being inexpensive and having excellent aging resistance, flame retardancy, and mechanical strength.
It is widely used in leather, sponge, cloth, building materials, and daily necessities. [Prior art and problems] When heating and foaming a vinyl chloride resin composition, particularly a vinyl chloride resin (PVC) composition containing a liquid plasticizer, the melt viscosity of the resin composition changes significantly with temperature. Because of their large size, foam generation was unstable depending on the foaming conditions, and the appearance and feel of the resulting foam was likely to be impaired. Therefore, the blowing agent and molding conditions must be tightly controlled within very narrow ranges to obtain a foam with optimal properties. Examples of blowing agents used in this case include azodicarbodiamide, dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, oxybisbenzenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide,
Organic and inorganic blowing agents such as toluenesulfonyl hydrazide, sodium bicarbonate, and calcium azide, inert gases such as carbon dioxide and nitrogen, and low-boiling point solvents can be used, but they are suitable for foaming ratio, colorless, odorless, flame retardant, and ease of handling. From this point of view, azodicarboxylic acid-based PVC foams are superior. However, the decomposition temperature is as high as 200°C or higher, which causes decomposition of PVC and hardening of the surface color during foam molding, and furthermore, the foam cells are disturbed, making it impossible to obtain a flexible foam. Therefore, it has been proposed to use a foaming aid such as a urea-based or fatty acid metal salt-based foam in combination with a blowing agent to lower the foaming temperature for practical use.However, urea-based foaming aids, such as urea-ethanolamine, are hygroscopic. In addition, it has the disadvantage of poor weather resistance. On the other hand, fatty acid metal salt-based foaming aids, such as zinc stearate,
Calcium stearate has been put into practical use because it has the effect of lowering the foaming temperature without impairing the heat resistance of PVC. However, if fatty acid metal salts are added to lower the foaming temperature, they may ooze out onto the surface of the molded product, impairing its appearance, or ooze out onto the molding metal surface during the processing process, contaminating the mold and roll surfaces, resulting in a glossy surface. There were drawbacks such as loss of color and color transfer. To improve these points, we have conventionally used butadiene-acrylonitrile copolymer (NBR), chlorinated polyethylene, and ethylene-vinyl acetate copolymer (EVA).
Attempts have been made to add elastic polymers, such as the combined use of However, in the case of NBR and chlorinated polyethylene, there is a problem in that the resulting foam becomes significantly colored during foaming and over time. On the other hand, the properties of EVA vary depending on the composition ratio, but EVA with a high vinyl acetate content, which is commonly used for PVC blends, has excellent compatibility with PVC.
In addition to making the cell state of the foam uniform and dense,
The texture of the foam is also good, and it is suitable for leather, foam soles,
It has been put to practical use as a cell control agent for foam molding of building materials, etc. (for example, Japanese Patent Publication No. 30948/1983). However, when making a foam, there is a process in which a cell conditioner is first added to PVC using a high-speed stirring mixer such as a Henschel mixer, but conventional EVA
Because of its viscosity, it has poor dry blending properties, such as turning in a high-speed mixing machine and forming lump-like shapes.For this reason, PVC is mixed with stabilizers, plasticizers, foaming agents, etc. first, and then cooled. It was necessary to increase equipment and processes, such as transferring the mixture to an agitating mixer and adding EVA after cooling the mixture. Furthermore, because of adhesion to the molding machine during the processing process, so-called plate-out properties were not sufficient, such as adhesion to calendar rolls and color transfer to sheets.
Therefore, it was necessary to frequently clean the molding machine, resulting in poor productivity. [Means for Solving the Problems] As a result of intensive research into PVC compositions free from the above-mentioned drawbacks, the present inventors discovered that vinyl ester-
Solubility coefficient in the presence of ethylene copolymer (VEE resin) [Encyclopedia of Polymer Science
The solubility coefficient values of each polymer according to the Solubility and Technology (published by Wiley-Inter-Science) were used. In the case of multiple components, calculations were made assuming additivity.
(hereinafter the same)] is obtained by polymerizing a polar vinyl monomer with a polarity of 8.5 to 15. By blending the modified VEE resin with PVC, the foam cell stabilization effect can be achieved, which is required for the foam itself. Not only does it have excellent inherent effects, but it also prevents the deterioration of dry blendability during high-speed agitation and oozing into the molding machine, which occurs when conventional EVA with a high vinyl acetate content is blended with PVC to form a foam. The present inventors have discovered that problems such as deterioration of plate-out properties caused by this can be solved, and have completed the present invention. That is, the present invention provides a polar resin having a solubility coefficient of 8.5 to 15 in the presence of (A) 100 parts by weight of PVC and (B) 100 parts by weight of a VEE resin having a vinyl ester content of 90 to 40% and an ethylene content of 10 to 60% by weight. Modified VEE resin obtained by polymerizing 5 to 50 parts by weight of vinyl monomer 1 to 50 parts by weight (C) 1 to 20 parts by weight of azodicarboxylic acid blowing agent (D) Fatty acid metal salt 0.5 -10 parts by weight of a PVC foam composition. Component (A) used in the present invention includes homopolymers of vinyl chloride, vinyl esters such as vinyl acetate, olefins such as ethylene, (meth)acrylic acid and its alkyl esters, and copolymers with vinyl chloride such as vinylidene chloride. Possible monomer 30% by weight
Copolymers with vinyl chloride containing the following proportions include ethylene-vinyl acetate copolymers, chlorinated polyethylene, and vinyl chloride graft copolymers in which vinyl chloride is added to thermoplastic polyurethane. Component (B) is produced under graft polymerization conditions by adding a polar vinyl monomer with a solubility coefficient of 8.5 to 15 in the presence of a VEE resin with a vinyl ester content of 90 to 40% by weight and an ethylene content of 10 to 60% by weight. It contains the modified VEE obtained in Even if the solubility coefficient of the vinyl monomer is lower than 8.5 or higher than 15, the compatibility with PVC decreases, and problems such as non-uniform foam cells and rough skin on the foam surface are likely to occur. . Furthermore, in the case of a polar vinyl monomer having a polarity lower than 8.5, the plate-out property deteriorates. Preferably, the modified VEE resin has a solubility coefficient of 8.5 to 10.
The VEE resin is a copolymer of ethylene and vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate, and has a vinyl ester content of 90% from the viewpoint of compatibility with PVC and processability. ~40% by weight and ethylene content 10-60% by weight, preferably vinyl ester content 80-50% by weight and ethylene content 20-50
It is a copolymer having a Mooney viscosity of 5 to 50 in weight percent. Up to half of the vinyl ester may be replaced with other vinyl monomers as long as the meaning of the present invention is not impaired. Polar vinyl monomers that polymerize in the presence of VEE resin include acrylic acids such as methyl acrylate, ethyl acrylate, and methyl methacrylate;
Methacrylic acid and its alkyl esters, aromatic vinyls such as styrene and α-methylstyrene, vinyl halides such as vinyl chloride, vinyl esters such as vinyl acetate, vinyl cyanides such as acrylonitrile, and vinyl monomers of these may be used in combination. The amount of modified VEE added is 1 to 50 parts by weight. At this time, if the amount of the modified VEE is less than 1 part by weight, not only will the cell stabilizing effect of the foam be insufficient;
The effect of preventing seepage into the molding machine (plate-out prevention effect) is insufficient. Moreover, if it exceeds 50 parts by weight, the strength of the foam will be insufficient. Examples of the azodicarboxylic acid blowing agent as component (C) include azodicarbodiamide, such as Uniform AZ (Otsuka Chemical Co., Ltd.) and Cellmic C (Sankyo Kasei Co., Ltd.). When the amount of the foaming agent added is 1 to 20 parts by weight, the foaming ratio and cell condition will be good. The fatty acid metal salt of component (D) preferably has 8 carbon atoms.
~22 divalent metal salts of saturated or unsaturated carboxylic acids. Such carboxylic acids include caprylic acid, capric acid, lauric acid, palmitic acid, stearic acid, oleic acid, etc., and their divalent metal salts include calcium, barium, zinc, lead or cadmium salts. The amount added is 0.5 parts by weight to 10
parts by weight, and if the amount is less than 0.5 parts by weight, the decomposition temperature of the blowing agent cannot be sufficiently lowered, or
If it exceeds 10 parts by weight, exudates will occur on the surface of the molded product.
Detracts from the appearance of the product. A liquid plasticizer can be added to the composition of the invention. Examples of such plasticizers include one or two of dioctyl phthalate, dibutyl phthalate, diheptyl phthalate, dioctyl adipate, dioctyl azelate, tricresyl phosphate, polyester plasticizers, epoxy plasticizers, etc.
More than one liquid plasticizer can be used. The amount of liquid plasticizer added is 30 to 120 parts by weight, preferably 50 to 80 parts by weight.
Parts by weight are appropriate. Furthermore, stabilizers for PVC, fillers, colorants, flame retardants, crosslinking agents, antioxidants, lubricants, etc. other than the above-mentioned foaming agents can be added as appropriate. To produce the foam, the above-mentioned various compounded materials are processed using a high-speed mixer such as a Henschel mixer, a mixing roll, a Banbury mixer, a calendar roll, an injection molding machine, an extrusion molding machine, etc., and then processed using a calendar sheet under normal pressure. Foaming method, pressure foaming method,
Conventionally known PVC foam manufacturing methods such as paste resin foaming method and two-stage foaming method can be employed. [Effects of the Invention] The composition for PVC foam of the present invention has fine and homogeneous cells in the foam, and has a wide processing temperature range in which a stable cell state can be obtained. In addition, because there is little migration of plasticizer, there is no sticky feeling on the surface of the product, and it does not contaminate textiles, furniture, etc. Furthermore, in terms of processability, conventional EVA resin can be used with a Henschel mixer.
PVC, stabilizer, and foaming agent are prepared, and a plasticizer is added while stirring and mixing.The plasticizer is absorbed into the PVC by heating to about 100℃, and after cooling to a low temperature of 70℃ or less, EVA resin is added. However, in the case of the composition of the present invention, the modified VEE resin is
Since it may be added to the water, the mixing tank and cooling time required for cooling are no longer necessary. or,
Conventionally, during calendering, the surface of the calender roll
Stains caused by leaching from the PVC compound,
It was necessary to frequently clean the roll surface, but in the case of the composition of the present invention, there is less dirt (plate-out) on the roll surface, and the elimination of cleaning of rolls and other forming machines can contribute to a significant reduction in production costs. .
Because of the above, it can be widely used for various foam molded products such as leather, foam, and building materials, and productivity during molding can be improved. [Example] Next, in order to further clarify the characteristics of the present invention, the present invention will be specifically described using Examples. Note that all parts and percentages in Reference Examples, Examples, and Comparative Examples are based on weight. Reference example 1 Sodium lauryl sulfate 1.5%, methylcellulose
Ethylene-vinyl acetate copolymer obtained by polymerizing an emulsion system containing 0.3% (SP value 8.8, ethylene content
41%, Mooney viscosity 10) to 200 parts of latex, 4 parts of calcium phosphate and distilled water were added to form an aqueous dispersion with a solids content of 20%, and 1.0 part of benzoyl peroxide was dissolved in the aqueous dispersion of methyl methacrylate (SP value 9.4). ) was added at room temperature and kept under stirring for 1 hour to allow the vinyl monomer to be absorbed into the latex particles. Subsequently, the temperature was raised to 75°C and reacted for 4 hours, and the temperature was further raised to 90°C and maintained for 2 hours. When the temperature was lowered and stirring was stopped, bead-shaped precipitates with a particle size of 0.2 to 0.5 mm were obtained, and when washed with water and dried, 238
Part of modified VEE (resin A) was obtained. Reference Example 2 Same as Reference Example 1 except that instead of 50 parts of methyl methacrylate in Reference Example 1, 30 parts of ethyl acrylate (SP value 9.2) in which 0.8 parts of benzoyl peroxide was dissolved and 10 parts of acrylonitrile (SP value 15) were used. A bead-like precipitate with a particle size of 0.1 to 0.3 mm was obtained, washed with water and dried, resulting in 225 parts of modified
VEE (resin B) was obtained. Reference Example 3 In Reference Example 1, vinyl acetate-ethylene copolymer (SP value 8.6, ethylene content 22%, Mooney viscosity 7) was used instead of vinyl acetate-ethylene copolymer, and methyl methacrylate was replaced with 241 parts of modified VEE was prepared in the same manner as in Reference Example 1 except that methyl acrylate (SP value 9.7) was used.
(Resin C) was obtained. Example 1 PVC with a degree of polymerization of 1300, azodicarbonamide (Uniform AZ, manufactured by Otsuka Chemical Co., Ltd.), barium stearate, and zinc stearate were placed in a Henschel mixer of 20 according to the composition shown in Table 1, and the mixture was heated at 1000 rpm. After adding dioctyl phthalate (DOP) with stirring, the rotation speed was increased to 2000 rpm and the resin temperature was raised to 110°C to absorb DOP. Resin temperature
When the temperature reached 110℃, add the resin (A) of Reference Example 1,
After mixing for an additional 3 minutes, the mixture was removed. At that time, powder form is preferable, and blocking is poor (dry blendability). Table 1 shows the dry blendability of the above mixture.
Next, 100 parts of the mixture was taken, and while kneading it with a mixing roll at 150°C, 1 part of a watching red pigment (red pigment) was added thereto, kneaded for 5 minutes, and then taken out. Next, 100 parts of the above PVC, 50 parts of DOP, 2 parts of titanium oxide
1 part of barium stearate and 1 part of zinc stearate were kneaded for 5 minutes, and the degree of red coloring was evaluated. The evaluation is preferably colorless, and the stronger the red, the worse. This is shown in Table 1 as plate-out properties. Dry blended using the Henschel mixer above, heated to 140°C using a Brabender Plastograph.
The mixture was kneaded at 45 rpm, and the gelation time (melting homogenization time) was measured. In terms of evaluation, a short gelation time is preferable, and a long gelation time is poor in workability. This is shown in Table 1 as gelling properties. Comparative Examples 1 to 2 Comparative Example 1 was the same as Example 1 except that resin (A) was not added, and EVA was used instead of resin (A).
(SP value 8.8, ethylene content 40%, Mooney viscosity 7)
The results are shown in Table 1 as Comparative Example 2, which was carried out in the same manner except that . Examples 2 to 8 The formulations shown in Table 2 were heated at 150°C on two rolls.
The mixture was kneaded for 5 minutes, and a 0.3 mm thick sheet was taken out. The obtained sheet was made into a 5 cm x 10 cm sheet using an adhesive emulsion (Evadik EP-11, manufactured by Dainippon Ink Chemical Co., Ltd.).
A foamed sheet was prepared by laminating the foam sheet onto a base fabric coated with and heating it in a hot air constant temperature machine at a predetermined temperature for 3 minutes. The magnification and average cell diameter of the foam were measured, and foams with fine and uniform cell diameters were evaluated as good. Next, the foam was sandwiched between polystyrene plates, and a pressure of 0.5 kg/cm ² was applied at 70°C to determine the amount of plasticizer transferred from the weight loss. The evaluation results are shown in Table 2. Comparative Examples 3 to 4 The same procedure as in Example 2 was carried out except that resin (A) was not added. Comparative Example 3 The same procedure was carried out except that barium stearate and zinc stearate were each added in an increased amount of 7.5 parts. The results are shown in Table 2 as Comparative Example 4. As is clear from the results in Table 2, the composition of the present invention is excellent in dry blending properties and plate-out properties, and is also excellent in terms of cell state of the foam and non-migration of plasticizer.

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Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of vinyl chloride resin (B) Vinyl ester having a vinyl ester content of 90 to 40% by weight and an ethylene content of 10 to 60% by weight
Modified vinyl ester-ethylene copolymer obtained by polymerizing 5 to 50 parts by weight of a polar vinyl monomer with a solubility coefficient of 8.5 to 15 in the presence of 100 parts by weight of ethylene copolymer 1 to 50 1. A composition for a vinyl chloride resin foam, comprising: parts by weight (C) of an azodicarboxylic acid foaming agent of 1 to 20 parts by weight (D) of fatty acid metal salts of 0.5 to 10 parts by weight.