JP2545124B2 - Process for producing vinyl chloride resin crosslinked foam - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for efficiently producing a vinyl chloride resin crosslinked foam which is homogeneous and has an excellent surface texture.

Technical background of the invention and its problems Vinyl chloride resin, ethylene / polar vinyl compound / carbon monoxide copolymer, organic peroxide and chemical blowing agent are used to produce a crosslinked foam of vinyl chloride resin. How to do
For example, it is disclosed in JP-A-59-80444. In the disclosed technology of this publication, generally, the vinyl chloride resin and the above-mentioned copolymer are melt-kneaded at a high temperature, and then the obtained melt-kneaded product is subjected to organic foaming and chemical foaming, although it depends on the ratio of each raw material used. A homogeneous mixture cannot be obtained unless the agents are mixed below their decomposition temperature. Such a method is complicated, and a slightly higher temperature is required for blending the organic peroxide and the like. Therefore, a coloring problem of the vinyl chloride resin may occur, or when an ethylene / polar vinyl compound / carbon monoxide copolymer whose polar vinyl compound component is vinyl acetate is used as the copolymer, deacetic acid particularly occurs. In addition, there was always a possibility that partial crosslinking or foaming would occur. Also, although the reason is not clear,
With such a method, it is difficult to obtain a foam having a sufficiently high expansion ratio, and the obtained foam often suffers from surface roughness and distortion.

The present inventors have made extensive studies to provide a method for producing a vinyl chloride resin crosslinked foam which can further simplify the production process in the conventional method as described above, and is economically and efficiently. It has been found that the use of the vinyl chloride resin can achieve the object and effectively avoid troubles such as coloring and unwanted side reactions. In addition, they have found that the expansion ratio can be easily increased, and that a molded product having excellent mechanical strength and having a small surface texture and a clean surface can be easily manufactured, and thus the present invention has been completed.

OBJECT OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and can further simplify the production process, and produce a crosslinked foam economically and efficiently. Of the vinyl chloride resin crosslinked foam, which is capable of producing a crosslinked foam which is homogeneous, has a high expansion ratio, and has a beautiful surface texture without being colored. It is intended to provide a manufacturing method.

SUMMARY OF THE INVENTION The method for producing a vinyl chloride resin crosslinked foam according to the present invention is 100 parts by weight of a vinyl chloride resin obtained by an emulsion polymerization method, and an ethylene / polar vinyl compound / carbon monoxide copolymer 50 to 200 parts by weight. And 1 to 20 parts by weight of organic peroxide,
1 to 50 parts by weight of a chemical foaming agent is added to the above melting point of the polymer to be 5
It is characterized in that it is melt-kneaded at a temperature higher than ℃ and lower than 130 ℃, molded into a predetermined shape, and then heated to a temperature of about 160 to 230 ℃ to crosslink and foam.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a method for producing a vinyl chloride resin crosslinked foam according to the present invention will be specifically described.

First, each component used for producing the vinyl chloride resin crosslinked foam according to the present invention will be specifically described.

In the present invention, a vinyl chloride resin obtained by an emulsion polymerization method is used as the vinyl chloride resin. Such vinyl chloride resin is obtained by emulsion-polymerizing vinyl chloride alone or vinyl chloride and a comonomer copolymerizable therewith in the presence of an emulsifier and a water-soluble polymerizable initiator, and is particularly preferably a particle. Diameter less than 5μm, especially 0.05-3μm
Those of a degree are preferable, and these are usually used as paste resins. The vinyl chloride resin obtained by such an emulsion polymerization method has a degree of polymerization of about 300 to 5000, particularly 500.
It is preferably about 2000.

Comonomers copolymerizable with vinyl chloride include unsaturated hydrocarbons such as ethylene, propylene and styrene,
Vinyl acetates such as vinyl acetate and vinyl propionate, unsaturated acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, diethyl maleate, vinyl ethers such as vinyl methyl ether, unsaturated nitriles such as acrylonitrile, vinylidene chloride, etc. Can be illustrated. It is desirable that such a comonomer copolymerizable with vinyl chloride is copolymerized in the vinyl chloride resin in an amount of 30% by weight or less, preferably 20% by weight or less.

As the ethylene / polar vinyl compound / carbon monoxide copolymer used in the present invention, ethylene is 40 to 80% by weight,
The polar vinyl compound is preferably present in an amount of 50 to 70% by weight.
A copolymer obtained by copolymerizing carbon monoxide in an amount of ˜55% by weight, preferably 20 to 35% by weight and carbon monoxide in an amount of 5 to 30% by weight, preferably 5 to 50% by weight is preferably used. Such a copolymer preferably has a melt flow rate of 0.5 to 100 g / 10 minutes, especially 1 to 50 g / 10 minutes, measured at 190 ° C. under a load of 2160 g.

Examples of the polar vinyl compound which is a copolymerization component of the above ethylene / polar vinyl compound / carbon monoxide copolymer include vinyl acetate, saturated vinyl carboxylate such as vinyl propionate, methyl acrylate, ethyl acrylate, and acrylic. Unsaturated carboxylic acid esters such as isopropyl acid ester, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, n-dodecyl acrylate, methyl methacrylate, n-octyl methacrylate, monomethyl maleate, diethyl maleate, etc. Examples thereof include vinyl ether, acrylonitrile, vinyl chloride and the like.

Such an ethylene / polar vinyl compound / carbon monoxide copolymer used in the present invention is, for example, Japanese Patent Publication No. 55-50.
It can be produced by the method described in JP-A-063.

In the present invention, an organic peroxide is used as the crosslinking agent. As such organic peroxides, various types of organic peroxides such as hydroperoxides, peroxyesters, dialkyl peroxides, diaryl peroxides, percarboxylic acids, and ketone peroxides are used, but crosslinking at the time of pre-kneading is minimized. In order to carry out the desired cross-linking at the time of cross-linking and foaming, the temperature of 50-160 ° C. when the half-life becomes 10 hours, especially 100-130 ° C., is naturally different depending on the production conditions. It is preferable to use an oxide. As such an organic peroxide, specifically, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl cumyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, 1,3- or 1, 4-bis- (tert-butyl-peroxyisopropyl) -benzene, dibenzoyl peroxide and the like can be exemplified.

In the present invention, a vinyl chloride resin crosslinked foam is manufactured using a chemical foaming agent.

Examples of such a foaming agent include azodicarbonamide, 1,1-azobisformamide, p, p'-oxy-
Bis- (benzenesulfonylhydrazide), sulfonylsemicarbazide, trihydrazinetriazine, dinitrosomethyleneamine, dinitrosopentamethylenetetramine, diazoaminobenzene and the like are used.

In the present invention, various additives can be added to the vinyl chloride resin crosslinked foam-forming composition for producing the vinyl chloride resin crosslinked foam, in addition to the above-mentioned essential components. For example, stabilizers such as fatty acid zinc, fatty acid calcium, and fatty acid barium, processing aids such as wax, antioxidants, foaming accelerators such as zinc oxide, pigments, fillers, liquid plasticizers, crosslinking aids, etc. should be added. You can

The use ratio of each component in the composition for forming a vinyl chloride resin crosslinked foam as described above changes variously depending on the type of raw materials used or the properties of the desired foam,
Generally, 100 parts by weight of vinyl chloride resin, ethylene
The polar vinyl compound / carbon monoxide copolymer is 10 to 200 parts by weight, preferably 50 to 150 parts by weight, the organic peroxide is 1 to 20 parts by weight, preferably 2 to 10 parts by weight, The chemical blowing agent is used in an amount of 1 to 50 parts by weight, preferably 10 to 40 parts by weight.

Next, a method for producing a vinyl chloride resin crosslinked foam from the above components will be specifically described.

First, a vinyl chloride resin, an ethylene / polar vinyl compound / carbon monoxide copolymer, an organic peroxide, a chemical foaming agent, and an additive that is added as necessary are melt-kneaded and intimately mixed. . At this time, after preliminarily mixing the vinyl chloride resin and the components other than the copolymer by using a mixing device such as a Henschel mixer and a ribbon blender, the obtained premix and the copolymer are rolled or extruded. It is preferable to employ a method of intimately kneading using a machine. The above-mentioned mixing is required to be carried out at a temperature equal to or lower than the decomposition temperature of the organic peroxide and the chemical foaming agent.
It is preferable to carry out at a temperature of not more than 0 ° C, especially 100 ° C or less. Further, the kneading of the pre-mixture and the copolymer is preferably carried out, for example, at a temperature higher than the melting point of the copolymer by 5 ° C. or more and 130 ° C. or less, particularly 120 ° C. or less.

After melt-kneading each component as described above, the melt-kneaded product obtained is molded into a predetermined shape such as a sheet, and then the obtained molded product is heated and maintained at a predetermined temperature to produce a crosslinked foam. can do. Although the conditions for cross-linking and foaming the molded product vary depending, of course, on the type of the cross-linking agent or the foaming agent, it is usually preferable to heat to a temperature of about 160 to 230 ° C.

Thus, according to the method for producing a vinyl chloride resin crosslinked foam according to the present invention, the vinyl chloride resin and the ethylene / polar vinyl compound / carbon monoxide copolymer are always obtained after melt-kneading at high temperature. It is not necessary to mix the organic peroxide and the chemical foaming agent in the melt-kneaded product at a temperature below their decomposition temperature, and the vinyl chloride resin and the components other than the above-mentioned copolymer are kneaded at a low temperature, and then obtained. The kneaded product may be kneaded with the above copolymer, which can simplify the manufacturing process.

EFFECTS OF THE INVENTION According to the present invention, a foam can be obtained under very simple operation and mild conditions. Therefore, a vinyl chloride resin crosslinked foam having uniform cells can be obtained without problems such as coloring of molded articles and generation of offensive odor due to decomposition of the copolymer. The vinyl chloride resin cross-linked foam obtained in the present invention is excellent in compression elastic recovery, has less molding strain, and has a clean surface. Further, since it is possible to manufacture a highly foamed product, a product having a foaming ratio of, for example, about 3 to 40 times can be arbitrarily obtained as desired.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A formulation having the composition shown below in Formulation-1
Put in 50 Henschel mixer, 600min while passing water
^The mixture was stirred at a rotation speed of ^-1 for 5 minutes. The resulting mixture was then added to an ethylene / vinyl acetate / carbon monoxide copolymer (MF
R 35 g / 10 minutes, ethylene 66% by weight, vinyl acetate 24% by weight, carbon monoxide 10% by weight) 100 parts by weight were added, and further mixed for 1 minute at a rotation speed of 100 min ⁻¹ . The obtained powder mixture was kneaded for 10 minutes with a 6-inch roll having a roll surface temperature of 80 ° C. (rotation speed front roll / rear roll = 20 min ⁻¹ / 20 min ⁻¹ ) to obtain a fractioned sheet. Further, the obtained divided sheet was pressed at a temperature of 120 ° C. for 3 minutes to obtain a pressed sheet having a thickness of 3 mm. When this press sheet was placed on a metal bath and heated in an oven at 180 ° C for 10 minutes, a highly elastic foam having a foaming ratio of 25 times was obtained. The surface texture of this foam was good, and the foamed state was also good.

Formulation-1 Polyvinyl chloride (Nippon Zeon Co., Ltd. paste vinyl chloride (emulsion polymerized vinyl chloride) Zeon-25, particle size 200 mesh, the total amount passed) 100 parts by weight Ba / Zn stabilizer 2.5 parts by weight Phosphite ester 0.5 parts by weight Epoxidized soybean oil 4 parts by weight Azodicarbonamide 30 parts by weight Dicumyl peroxide 0.7 parts by weight Zinc oxide 2.1 parts by weight Comparative Example 1 A formulation having the composition shown in the following formulation-2 was prepared.
The mixture was put into a 50 Henschel mixer, and a powder mixture was obtained in the same manner as in Example 1.

The obtained powder mixture was applied to a 6-inch roll with a roll surface temperature of 130 ° C (rotational speed front roll / back roll = 20 min ^-1 / 20 mi
When kneaded at n ⁻¹ ) for 10 minutes, the polyvinyl chloride particles and the ethylene / vinyl acetate / carbon monoxide copolymer were not dispersed, so the sheet could not be separated and rolled.

Blend-2 Polyvinyl chloride (Mitsui Toatsu Chemicals Co., Ltd., Vinylon 30)
00M Suspension polymerization PVC, particle size 110μm) 100 parts by weight Ba / Zn stabilizer 2.5 parts by weight Phosphite ester 0.5 parts by weight Epoxidized soybean oil 4 parts by weight Azodic carbon amide 30 parts by weight Dicumyl peroxide 0.7 parts by weight Oxidation Zinc 2.1 parts by weight Comparative Example 2 The same composition as in Comparative Example 1 was charged into a 50 Henschel mixer, and a powder mixture was obtained in the same manner as in Example 1. When the obtained powder mixture was kneaded with a 6-inch roll having a roll surface temperature of 140 ° C. in the same manner as in Comparative Example 1, the foaming agent started to decompose and bubbles were observed in the sheet. Further, in the same manner as in Comparative Example 1, no roll was released.

Therefore, as long as the blend of blend-2 is used, kneading in a single stage is not possible, and as shown in Comparative Example 3, polyvinyl chloride and ethylene / vinyl acetate / carbon monoxide copolymer were used in the first stage. After sufficiently kneading at 160 to 180 ° C, it is necessary to lower the temperature below the decomposition temperature of the blowing agent (110 to 130 ° C) and knead the blowing agent and the crosslinking agent.

Comparative Example 3 A formulation having the composition as shown in the following formulation-3 was prepared.
The mixture was put into a 50 Henschel mixer and mixed and stirred for 5 minutes at a rotation speed of 600 min ⁻¹ while passing water in the same manner as in Example 1. After this, ethylene / vinyl acetate / carbon monoxide copolymer 100
Parts by weight were added and further mixed for 1 minute at a rotation speed of 100 min ⁻¹ . The obtained powder mixture is a 6 inch roll (rotational speed front roll / rear roll = 20 min, roll surface temperature 170 ° C)
^-1 / 20 min ^-1 ) was kneaded for 10 minutes to obtain a dispensing sheet.

After this, the temperature of the 6-inch roll was lowered and the dispensing sheet was kneaded at a surface temperature of 120 ° C. At the time when the sheet was wound around the roll, the remaining materials (formulation-4) were added, and the mixture was kneaded for 7 minutes to obtain a divided sheet. This dispensing sheet was obtained. This divided sheet was pressed at 120 ° C. for 3 minutes to obtain a pressed sheet having a thickness of 3 mm. This press sheet is placed on a metal bath and the same method as in Example 1 is used.
When heated in an oven at 0 ° C. for 10 minutes, a high foam having a foaming ratio of 20 times was obtained. This foam was distorted and curved as compared to the foam of Example 1.

Blend-3 Polyvinyl chloride (Mitsui Toatsu Chemicals Co., Ltd., Vinylon 30)
00M Suspension polymerized vinyl chloride, particle size 110 μm) 100 parts by weight Ba / Zn stabilizer 2.5 parts by weight Phosphite ester 0.5 parts by weight Epoxidized soybean oil 4 parts by weight Blend-4 azodicarbonamide 30 parts by weight Dicumyl peroxide 0.7 Parts by weight zinc oxide 2.1 parts by weight Example 2 In Example 1, ethylene / vinyl acetate / carbon monoxide copolymer was replaced with ethylene / normal butyl acrylate /
Carbon monoxide copolymer (MFR 7g / 10 minutes, ethylene 60% by weight, normal butyl acrylate 30% by weight, carbon monoxide
The same procedure as in Example 1 was carried out except that the content was changed to 10% by weight), and a highly elastic foam having a foaming ratio of 26 times and having no distortion was obtained. The surface texture of this foam was good, and the foamed state was also good.

Comparative Example 4 In Comparative Example 3, the ethylene / vinyl acetate / carbon monoxide copolymer was replaced with ethylene / normal butyl acrylate /
A foam having a foaming ratio of 19 times was obtained by the same procedure as in Comparative Example 3 except that the carbon monoxide copolymer was used. The obtained foam was curved similarly to Comparative Example 3.

Claims (1)

(57) [Claims] 1. A vinyl chloride resin obtained by an emulsion polymerization method 100 parts by weight, an ethylene / polar vinyl compound / carbon monoxide copolymer 50 to 200 parts by weight, and an organic peroxide 1 to 20 parts by weight. 1 to 50 parts by weight of a chemical foaming agent is melt-kneaded at a temperature of not less than 5 ° C. and not more than 130 ° C. higher than the melting point of the above copolymer, molded into a predetermined shape, and then heated to a temperature of about 160 to 230 ° C. A method for producing a vinyl chloride resin crosslinked foam, comprising: