JPH034574B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride resin foam and a method for producing the same, and more particularly to a vinyl chloride resin foam that has excellent dimensional stability, heat resistance, and extremely excellent moldability with a small amount of plasticizer, and a method for producing the same. It is something. PVC resin foam has the characteristics of flexibility, elasticity, waterproof/moisture proof, heat insulating effect, and weather/chemical resistance, so it is used in electrical materials, architecture, civil engineering, vehicles,
It is used in a wide range of clothing, etc. However, conventional soft vinyl chloride resin foams have a large amount of plasticizer, which causes the plasticizer to ooze out, which limits their use from a sanitary standpoint.They also have low heat resistance and a low elongation rate when heated. It had drawbacks such as poor moldability and poor texture due to its specific gravity of 0.1 or more and insufficient flexibility. In view of the shortcomings described by the present inventors, we have developed a vinyl chloride resin foam that has no amount of plasticizer or even if it exists, it is smaller than conventional vinyl chloride resin foams, has excellent heat resistance, and has extremely excellent moldability. As a result of intensive research for development, it was discovered that all of the drawbacks of conventional products could be overcome by adding acrylonitrile-butadiene copolymer vulcanized with sulfur to a vinyl chloride resin containing ethylene component as the main component. They discovered this and completed the present invention. That is, the present invention contains 2 to 12% by weight of ethylene component and has a degree of polymerization of 500 to 1500.
It consists of 95 to 50% by weight of a vinyl chloride-ethylene copolymer which is A vinyl chloride resin foam having an expansion ratio of 5 to 25 times and a heating elongation rate of at least 120% at a temperature of 110°C, and an ethylene content of 2 to 12% by weight.
vinyl chloride-ethylene copolymer with a degree of polymerization of 500 to 1500, 95 to 50% by weight, and acrylonitrile containing 16 to 45% by weight of an acrylonitrile component.
5-50% by weight of butadiene copolymer, 0.5-2.5% by weight of sulfur based on the acrylonitrile-butadiene copolymer, 0-100% by weight of plasticizer based on the vinyl chloride-ethylene copolymer, vinyl chloride- A method for producing a vinyl chloride resin foam, which comprises heating a mixture of an ethylene copolymer and an acrylonitrile-butadiene copolymer and a blowing agent of 5 to 30% by weight to vulcanize and foam the mixture. The gist of this paper is as follows. Vinyl chloride as the vinyl chloride resin in the present invention
Ethylene copolymers are used. The ethylene component of the vinyl chloride-ethylene copolymer is contained in the vinyl chloride resin in an amount of 2 to 12% by weight. By including the ethylene component in the vinyl chloride resin, an internal plasticizing effect can be obtained, and the use of plasticizer can be reduced. If the ethylene component is less than 2% by weight, the internal plasticizing effect is low, requiring the use of a large amount of plasticizer, resulting in leaching of the plasticizer, and the expansion ratio is not high, which is not preferable. Moreover, if it exceeds 12% by weight, the use of a plasticizer is not required and the expansion ratio becomes high, but elasticity becomes weak, which is not preferable. The degree of polymerization of the vinyl chloride-ethylene copolymer containing ethylene in this range is:
500 to 1500 are used. If the degree of polymerization is less than 500, the foaming ratio will be high, but the elasticity will be weak, the shrinkage rate will be high, and the dimensional stability will be poor, so it is not preferable. Moreover, if the degree of polymerization exceeds 1500, the shrinkage rate will be low, but the foaming ratio will not be high, which is not preferable. Therefore, in the present invention, from the viewpoint of expansion ratio, elasticity, stiffness, dimensional stability, and use of plasticizer, a vinyl chloride-ethylene copolymer with an ethylene component of 2 to 12% by weight and a degree of polymerization of 500 to 1500 is used. It is something that will be done. In the present invention, an acrylonitrile-butadiene copolymer is included in the vinyl chloride-ethylene copolymer. By including the acrylonitrile-butadiene copolymer in the vinyl chloride-ethylene copolymer, it is possible to improve the elongation rate and obtain suitable impact resilience, which is the objective of the present invention. Furthermore, since the amount of plasticizer used is reduced, the problem of plasticizer leaching and migration is greatly reduced compared to conventional soft vinyl chloride resin foams having the same degree of flexibility. The acrylonitrile-butadiene copolymer needs to be vulcanized with sulfur. When not vulcanized, the elongation rate at room temperature is improved, but the elongation rate during hot molding is poor. Since one of the features of the foam of the present invention is excellent heat moldability, it is required that it be vulcanized. Examples of sulfur for vulcanizing the acrylonitrile-butadiene copolymer include powdered sulfur and sulfur-containing sulfur compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabutylthiuram disulfide.
Examples include disulfide, dipentamethylenethiuram tetrasulfide, morpholine disulfide, and the like, and these may be used alone or in combination of two or more. These sulfurs are 0.5~
Used in a range of 3.0% by weight. If the amount of sulfur exceeds 3.0% by weight, the vulcanization rate will be high and the rigidity will be too strong and the flexibility will be impaired. This is not preferable because the elongation rate becomes poor. Also, below 0.5% by weight,
It is not preferable because it has the disadvantage that the vulcanization rate is low, the heat resistance is poor, and a good molded product cannot be obtained. In addition to the above-mentioned sulfur, it is also possible to use vulcanization accelerators. As such a vulcanization accelerator, the above-mentioned sulfur-containing sulfur compounds are also used, but in addition, 2-mercapto benzothiazole di-benzothiazyl disulfide, zinc salt of 2-mercapto benzothiazole, Zn-dimethyl dithio Carbamate, Zn-diethyl dithiocarbamate, Zn-di-n-butyl-dithiocarbamate, ortho-tolyl biguanite, ethylene thiourea, acetaldehyde-ammonia, isopropyl zinc xanthate, zinc white, etc. are used. These vulcanization accelerators are 0.5~
Used in a range of 8.0% by weight. Note that the use of organic peroxides such as t-butyl peroxide and cumene hydroperoxide as vulcanizing agents and vulcanization accelerators is not preferred because it discolors the vinyl chloride-ethylene copolymer of the present invention. In the present invention, a sulfur-vulcanized acrylonitrile-butadiene copolymer is used together with a vinyl chloride-ethylene copolymer containing 2 to 12% by weight of ethylene component and having a degree of polymerization of 500 to 1500. However, the proportions used are 95 to 50% by weight of the vinyl chloride-ethylene copolymer and 5 to 50% by weight of the acrylonitrile-butadiene copolymer. If the amount of acrylonitrile-butadiene copolymer relative to vinyl chloride-ethylene copolymer exceeds 50% by weight, aging resistance, flame retardance, and weather resistance will deteriorate, and not only will it be disadvantageous in terms of cost, but also the vinyl chloride resin This is not preferable because the properties of the material are impaired. On the other hand, if it is less than 5% by weight, the heating elongation rate,
This is not preferable because the rebound resilience deteriorates. In the vinyl chloride resin foam of the present invention, the proportions of vinyl chloride-ethylene copolymer and acrylonitrile-butadiene copolymer are changed as appropriate, taking into consideration heat resistance, use of plasticizer, moldability, and other physical properties. be done. That is, when no plasticizer is used, the amount of acrylonitrile-butadiene copolymer is close to 50% by weight, and when a plasticizer is used to increase flexibility and expansion ratio, the amount of acrylonitrile-butadiene copolymer is Preferably, the amount of polymer is close to 5% by weight. Acrylonitrile-butadiene copolymers are known to have various acrylonitrile contents, and changing the content can change the properties of the acrylonitrile-butadiene copolymer, such as flexibility, oil resistance, etc. well known. According to the present invention, an acrylonitrile component of 16
An acrylonitrile-butadiene copolymer containing ~45% by weight is used. If the amount of the acrylonitrile component exceeds this range, the flexibility and heating elongation rate of the resulting product will decrease, making it impossible to increase the foaming ratio and making molding difficult. component) becomes relatively large, resulting in a product with poor oil resistance. A plasticizer is used in the present invention to increase such flexibility and expansion ratio. Examples of the plasticizer include tricresyl phosphate, tris-isopropylphenyl phosphate, tributyl phosphate, and triethyl phosphate. Phate, trioctyl phosphate, tris-β-chloroethyl phosphate, tris-dichloropropyl phosphate, triphenyl phosphate,
Butyl benzyl phthalate, dilauryl phthalate, diphenyl phthalate, dibutyl phthalate, dimethyl phthalate, diethyl phthalate,
Dioctyl phthalate, dioctyl adipate,
Diisodecyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl maleate, dibutyl maleate, dibutyl fumarate, etc. are used. These plasticizers are used in an amount of 0 to 80% by weight based on the vinyl chloride-ethylene copolymer and the acrylonitrile-butadiene copolymer. Conventional soft vinyl chloride resin foams contain 70 to 100% by weight or more of plasticizer based on the vinyl chloride resin, which causes leaching and migration of the plasticizer, but in the foam of the present invention, the plasticizer The presence of the acrylonitrile-butadiene copolymer greatly reduces the amount of plasticizer required to achieve the same level of flexibility as conventional flexible PVC resin foams. Therefore, such problems do not occur or are rare. In the present invention, the resulting vinyl chloride resin foam
The heating elongation rate at a temperature of 110℃ is at least 120
% is required. Conventional soft vinyl chloride resin foams have a heat elongation rate of 105% at a temperature of 110°C, so when heat-molded like foamed polystyrene, the elongation is insufficient, resulting in breakage during molding, resulting in undesirable results. The disadvantage was that it was not possible to obtain a product with a certain shape. In order to obtain sufficient formability, a heating elongation rate of 150% or more is usually required at the above temperature. If the foam has a heating elongation rate of 150% or more, it is possible to obtain a foam molded product having a drawing ratio of 0.5 or more with respect to the diameter of 1. The use of plasticizers is restricted due to the relationship with the heating elongation rate. The higher the amount of plasticizer, the more flexible the
Although the expansion ratio and elongation rate are improved, the heat resistance deteriorates and the heat moldability is inhibited. Furthermore, when the amount of acrylonitrile-butadiene copolymer is approximately 5% by weight and the amount of plasticizer is decreased, the heat resistance is good, but the expansion ratio and elongation rate are poor. Therefore, in the present invention, the amount of plasticizer varies depending on the amount ratio of vinyl chloride-ethylene copolymer and acrylonitrile-butadiene copolymer, but 0 to 80% by weight, preferably 0
Used in the range of ~60% by weight. By using a plasticizer within this range, a vinyl chloride resin foam having a heat elongation rate of at least 120% at a temperature of 110°C can be obtained. The vinyl chloride resin foam of the present invention is expanded 5 to 25 times. Foaming less than 5 times is not preferable because there is no flexibility and poor heat moldability.
Further, foaming 25 times or more is not preferable because it has the disadvantage of poor heat resistance and inhibited heat moldability. A blowing agent is used to obtain such a blowing ratio. As blowing agents, ammonia carbonate, bicarbonate of soda,
Dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, p,p-oxybisbenzenesulfonylhydrazide, azobisisobutyronitrile, azodicarbonamide, etc. alone or in combination
It is used in combination of more than one species. It is also possible to use a blowing aid to lower the decomposition temperature of the blowing agent. As foaming aids, urea-based aids, organic acid-based aids, and metal salt-based aids are used. Examples include fatty acids such as stearic acid and lauric acid, zinc, calcium, lead, and barium salts of fatty acids. zinc oxide,
Examples include metal oxides such as litharge, and these foaming aids may be used alone or in combination of two or more. In addition, the vinyl chloride resin foam of the present invention may contain, for example, white rhubarb, other calmos, calcium carbonate, magnesium carbonate, waxite clay, hard clay, etc., in order to increase rigidity and bending strength. Furthermore, in order to obtain the vinyl chloride resin foam of the present invention, a lubricant is used for the purpose of improving roll kneading, improving roll separation, and improving kneading in an extruder. Such lubricants include:
Liquid paraffin, natural paraffin, micro wax, polyethylene wax, chlorinated naphthalene, stearic acid, lauric acid, stearic acid amide, palmitic acid amide, methylene bisatearoamide, ethylene bissteramide, ethylene glycol monostearate, etc. They may be used alone or in combination of two or more. Furthermore, in the present invention, it is also possible to add colorants, ultraviolet absorbers, stabilizers, etc. To obtain the vinyl chloride resin foam of the present invention,
Although various methods can be used, press foaming methods and extrusion foaming methods are preferably employed. When the vinyl chloride resin foam of the present invention is obtained by press foaming, vinyl chloride-ethylene copolymer, acrylonitrile-butadiene copolymer, vulcanizing agent such as sulfur, vulcanizing aid, blowing agent, blowing aid , lubricant, etc. are thoroughly kneaded with a mixing roll at a temperature of 60 to 100℃, and then a sheeting roll is used to mix the ingredients.
The mixture having the above composition is formed into a sheet or a plate.
This sheet or plate is cut to a certain size, and the cut sheet or plate is filled into a mold that can be heated from the top and bottom so that the filling rate is 80 to 95%. . After filling, under pressure 150 ~
The mixture is heated at a temperature of 190 DEG C. for about 15 to 25 minutes to vulcanize the acrylonitrile-butadiene copolymer and decompose the blowing agent. After completion of vulcanization and decomposition, it is cooled to room temperature and the sheet or plate is taken out.
After taking it out, heat it for about 10~ using a heating medium such as steam.
The vinyl chloride resin foam of the present invention can be obtained by heating at a temperature of 90 to 100°C for 25 minutes. Examples of the present invention are shown below. Examples Parts by weight Vinyl chloride-ethylene copolymer (contains 4% ethylene component, degree of polymerization 1050) 70 Acrylonitrile-butadiene copolymer (33% acrylonitrile component, The Goodyear T.
and Chemi Gum N-615B manufactured by R.Co.) 30 Sulfur (vulcanizing agent) 0.5 Zinc white (vulcanizing agent) 1.5 Tetrathiuram disulfite (vulcanizing aid)
0.07 Shiroka (reinforcing agent) 12 Azodicarbonamide (foaming agent) 13 Zinc stearate (lubricant) 1 Dibutyl phthalate (plasticizer) 50 Dioctylphthalate (plasticizer) 50 A mixture having the above formulation was maintained at a temperature of 80°C. After thorough kneading using a mixing roll, the mixture was formed into a sheet having a thickness of 13 mm using a sheeting roll maintained at the same temperature. This sheet (2.3 kg) was cut into a size of 450 mm x 450 mm. Put the cut sheet into a mold with a size of 460 mm x 160 mm and a mold cavity with a thickness of 10 mm,
After the mold was closed, it was heated under pressure at a temperature of 180° C. for 20 minutes to vulcanize the acrylonitrile-butadiene copolymer and decompose the blowing agent. After completion of vulcanization and decomposition, the inside of the mold was cooled and the sheet was taken out. The sheet cooled to room temperature was immersed in hot water at a temperature of 90 to 100° C. for 20 minutes to cause foaming, and then dried. The obtained foam had a size of 1100 mm x 1100 mm and a thickness of 25 mm, and the expansion ratio of this foam was 15 times (specific gravity was 0.08). This foam had uniform fine cells and was extremely soft to the touch. The physical properties of this foam are shown in Table 1. Table 1 also shows the physical properties of typical conventional vinyl chloride resin foams (plasticizer amount: 80% by weight relative to vinyl chloride resin). The foam obtained in this way has a thickness of 3 mm.
The sliced sheet is heated for 18 seconds in an oven maintained at a temperature of 175℃ using a commonly used molding machine for expanded polystyrene to soften it.
When molded into a cup having dimensions of 130 mm and a depth of 80 mm (drawing ratio 1:0.6), the sheet did not tear and a cup having a uniform thickness was obtained. When the conventional vinyl chloride resin foams shown in Table 1 were formed in the same manner as above, the sheets were broken and no cups were obtained. When molding was performed with various diameters and depths, the diameter
A molded body was obtained with a bento box-like shape having dimensions of 180 mm and depth of 25 mm (drawing ratio 1:0.14). As described above, the vinyl chloride resin foam of the present invention has extremely superior heat moldability compared to conventional vinyl chloride resin foams.

【table】

[Table] Measured.
According to Table 1-1, the foam of the example (that is, the foam of the present invention) has a 180% improvement in elongation rate compared to the vinyl chloride resin foam of the comparative example, but there is also a dimensional change when heated. The Example foam shrinks only 5.2% in the longitudinal direction, while the conventional foam shrinks 9.3% in the longitudinal direction. Furthermore, according to the heating properties in Table 1-2, while conventional foams melt at 150°C,
The foam of the example did not melt even at 150°C. From the above, the foam of the example (the one of the present invention) has superior heat resistance and elongation rate when heated compared to conventional foam, so it is an excellent material. It has moldability.

Claims (1)

[Scope of Claims] 1 Contains 2 to 12% by weight of ethylene component and has a polymerization degree of
Vinyl chloride-ethylene copolymer with a molecular weight of 500 to 1500
95 to 50% by weight, and 5 to 50% by weight of an acrylonitrile-butadiene copolymer containing 16 to 45% by weight of an acrylonitrile component and vulcanized with sulfur at 110°C at an expansion ratio of 5 to 25 times. A vinyl chloride resin foam having a heat elongation rate of at least 120% at a temperature of at least 120%. 2 Contains 2 to 12% by weight of ethylene component and has a polymerization degree of
Vinyl chloride-ethylene copolymer with a molecular weight of 500 to 1500
95-50% by weight, 5-50% by weight of acrylonitrile-butadiene copolymer containing 16-45% by weight of acrylonitrile component, 0.5-2.5% by weight of sulfur, chloride added to the acrylonitrile-butadiene copolymer 0 to 80% by weight plasticizer for vinyl-ethylene copolymer and acrylonitrile-butadiene copolymer, 5 to 30% by weight for vinyl chloride-ethylene copolymer and acrylonitrile-butadiene copolymer
A method for producing a vinyl chloride resin foam, which comprises heating and foaming a mixture comprising a foaming agent of % by weight.