JPS6023131B2 - Manufacturing method of vinyl chloride resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing a foam from a sol vinyl chloride resin composition into which gas is uniformly dispersed through mechanical treatment.

There are two typical methods for producing foam from vinyl chloride resin plastisol.

One method is to mix an organic or inorganic chemical foaming agent into plastisol and heat it to a high temperature (hereinafter referred to as "chemical foaming").
That's what it means. ), and the other is a method in which plastisol is subjected to mechanical treatment such as foaming to uniformly disperse and mix gas into plastisol (hereinafter referred to as "mechanical foaming"). According to the former method, harmful gases are generated due to the decomposition of the chemical blowing agent during heating, causing environmental pollution, and the resulting foam has the disadvantage that the cell structure tends to be discontinuous and the compression set is large. On the other hand, the latter method has the major characteristics that the cell structure becomes more continuous than chemical foaming and the compression set is extremely small, but it is not possible to use high temperatures for heating and melting during manufacturing. Therefore, it took a long time to heat, making it impossible to improve productivity, and it was also relatively difficult to produce thick foams. In other words, in the case of conventional plastisol, when producing a foam sheet, it can be heated to a temperature of around 200 ℃, but when making a foam sheet by dispersing gas and foaming with the same composition, the temperature is about 150 to 17,000 ℃. It can only be heated. If heated to a temperature higher than this, the sol viscosity and melt viscosity will decrease, flow will occur due to heat, and the bubbles will collapse, making it impossible to obtain the desired expansion ratio.
This results in a product with inferior commercial value. Furthermore, even if heated at a low temperature for a long time, the original physical properties of the sol will not be achieved at this temperature, even if the sol is heated for a considerable period of time, and as the thickness of the sheet increases, it will take a longer time to heat, and the bubbles will not collapse. There were major drawbacks that were difficult to avoid. The present inventors conducted intensive studies with the aim of efficiently mechanically foaming vinyl chloride resin in a short time and improving the physical properties of the produced foam, and found that at least one part of the foamable resin composition It has been found that the objects of the present invention can be achieved by using a vinyl chloride copolymer having a hydroxyl group or a carboxyl group in the molecule as a component, and by using a crosslinking agent for the copolymer in combination.

That is, the gist of the present invention mainly consists of a vinyl chloride copolymer having a hydroxyl group or a carboxyl group in the molecule, a crosslinking agent and a plasticizer having at least two functional groups in each molecule that can react with the hydroxyl group or the carboxyl group. A vinyl chloride resin foam, characterized in that a sol-like vinyl chloride resin composition as an ingredient is mechanically treated to uniformly mix gas into the composition, and then the composition is heated to gel. It depends on the manufacturing method.

To explain the present invention in detail, a vinyl chloride copolymer (hereinafter referred to as " It is sometimes referred to as "crosslinkable vinyl chloride copolymer".

) can be obtained by, for example, copolymerizing a vinyl chloride monomer with a comonomer having a hydroxyl group or a carboxyl group in the molecule. Specific examples of such comonomers include 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, ethyl-2-hydroxyethyl fumarate, hydroxybutyl vinyl ether , methacrylic acid, acrylic acid, itaconic acid, monobutyl maleate, undecylenic acid, and the like. Furthermore, the vinyl chloride copolymer having the above-mentioned crosslinkable group preferably contains 0.5 to 10% by weight of the above-mentioned comonomer, and the comonomer content is less than 0.5% by weight. It is difficult to prevent bubbles from collapsing during heating gelation due to insufficient crosslinking, and 1% by weight
If the amount is larger, the excellent physical properties of the vinyl chloride resin itself tend not to be exhibited.

In addition, this crosslinkable vinyl chloride copolymer can be prepared by a known method,
That is, it may be obtained by any polymerization method such as suspension, emulsification, or bulk. However, in the present invention, those obtained by emulsion polymerization are most preferred from the viewpoints of particle size, meltability, crosslinkability, and sol adjustment. The pinyl chloride resin composition of the present invention contains, as a resin component, a non-crosslinkable vinyl chloride polymer that does not have crosslinking properties in addition to the above-mentioned vinyl chloride copolymer having a crosslinkable group. It's okay,
Specific examples include vinyl chloride photopolymers, copolymers of vinyl chloride monomers and comonomers that do not have crosslinkable groups such as hydroxyl groups or carboxyl groups, such as vinyl chloride monomers and vinyl ethers, acrylic esters,
Examples include copolymers with olefins and the like, and these may also be obtained by any known method such as suspension polymerization, emulsion polymerization, or bulk polymerization.

The blending ratio of the vinyl chloride copolymer having a crosslinkable group and the vinyl chloride copolymer not having crosslinkability in the vinyl chloride resin composition of the present invention is not particularly limited; It is advisable to incorporate the latter in an amount of up to 9 parts by weight, preferably up to 8 parts by weight, per 100 parts by weight of the total amount.

The crosslinking agent used in the vinyl chloride resin composition of the present invention is a compound having two or more functional groups in one molecule that can react with the vinyl chloride copolymer having a hydroxyl group or a carboxyl group. .

Such crosslinking agents include, for example, isocyanate groups, carboxyl groups, hydroxyl groups, epoxy groups, alkoxyalkylamino groups, hydroxyalkylamino groups,
Compounds having an amino group, alkyl mono- or di-substituted amino groups, anhydrides of dibasic acids, etc., specifically, tolylene diisocyanate, diphenylmethane diisocyanate, trimethylolpropane tolylene diisocyanate and adducts thereof, Examples include polymethylene phenyl isocyanate, succinic acid, glutamic acid, adipic acid, phthalic acid, phthalic anhydride, cyclohexanedicarboxylic anhydride, triglycidyl isocyanurate epoxy resin, triethylenetetramine, methylolmelamine, butoxymethylmelamine, etc. The amount of the crosslinking agent used varies depending on its type, but is preferably in the range of 0.2 to 10 parts by weight based on the content of the crosslinkable vinyl chloride copolymer.
The plasticizer to be blended as one component of the vinyl chloride resin composition of the present invention is not particularly limited, but specific examples include jetyl phthalate, dibutyl phthalate, dioctyl phthalate, didecyl phthalate. One or more types of plasticizers known as plasticizers for vinyl chloride resins, such as , butylbenzyl phthalate, dialkyl adipate, etc., can be used, and the blending amount is determined depending on the desired magnification and hardness, that is, when molded. It is determined as appropriate depending on the use of the foam.

In particular, it is preferable to use 50 parts by weight or more per 100 parts by weight of the resin component. However, when the vinyl chloride resin composition is mechanically processed, it is necessary to create a state in which air bubbles can be uniformly mixed therein, and the most preferable form is that it be in the form of a sol. Furthermore, the amount of plasticizer can be increased or decreased by using a diluent or the like.
In addition to the above-mentioned components, the vinyl chloride resin composition of the present invention may contain processing additives such as heat stabilizers, fillers, diluents, and solvents depending on the purpose.

Among these, as the heat stabilizer, those commonly used in the foaming process of ordinary pinyl chloride resin can be used, but among them, a heat stabilizer containing a zinc compound as a main component is most suitable. or,
The proportion used is not particularly limited, but may be about 0.5 to 8 parts by weight per 10 parts by weight of the resin component. The sol-like vinyl chloride resin composition of the present invention is produced by keeping the above-mentioned components at a temperature below which crosslinking reaction does not occur using a known mixing device such as a ribbon blender, a kebab machine, or a Henschel mixer. It can be obtained by blending.

The present invention is to mix and disperse a gas into the composition and then gel it.

The gas can be mixed into the composition by blowing the gas into the composition or forcibly using a batch-type whisker, continuous-type whisker, or foam-mixing/dispersing machine, such as an Oaks mixer or a planetary mixer. The gas is uniformly mixed and dispersed in the composition by a mechanical treatment method such as steaming and foaming. Of course, a foam stabilizer such as a silicoso resin or an emulsifier can be used during foaming. The gas used in the method of the present invention is not particularly limited, but it may normally be air, and other gases such as nitrogen gas and carbon dioxide that do not react with the vinyl chloride resin composition or are dissolved and absorbed in plasticizers, diluents, etc. An inert gas that is not used is used. A sol-like vinyl chloride resin composition in which a gas is mixed and dispersed can be applied to release paper, woven fabric, glass, or metal, and then heated at high temperature to gel it to obtain a foam. I can do it. Of course, it may also be made into a foam by a method such as Western mold extrusion or Rentsugi extrusion. The heating temperature is preferably in the range of 180 to 220°C, and the heating method is not particularly limited, but methods such as hot air heating and infrared heating are usually employed. According to the method of the present invention, when heated, the crosslinkable vinyl chloride resin contained in the vinyl chloride resin composition is crosslinked while containing air bubbles and loses fluidity, so that the air bubbles are collapsed. It is possible to obtain a dense and uniform foam with an extremely high expansion ratio.

In addition, since the air bubbles contained in the composition do not collapse during heating, the heating temperature can be maintained high, allowing efficient operation in a short time, and even thick foam can be easily produced. It also makes it possible to obtain high-speed manufacturing. The resulting foam is heated and melted at high temperatures to form a gel, so it can fully demonstrate the original performance of the pinyl chloride resin, and has great industrial value as a first-class cushion floor application. expensive. Next, the method of the present invention will be explained with reference to Examples, but the method of the present invention is not limited to the following Examples unless the gist of the method is exceeded.

The following two types of crosslinkable vinyl chloride copolymers (emulsion polymerization products) were used in Examples and Comparative Examples.

Vinyl chloride copolymer containing 2% by weight of 2-hydroxyethyl methacrylate, degree of polymerization P: 1400 [B- Vinyl chloride copolymer containing 3% by weight monobutyl maleate, degree of polymerization P: 1400 Example 1. Comparative Example 1 Parts by weight of crosslinkable copolymer 10, 9 parts by weight of dioctyl phthalate (DOP), 5 parts by weight of tolylene diisocyanate, 3 parts by weight of calcium-zinc liquid stabilizer, 4 parts by weight of silicone foam stabilizer A vinyl chloride resin composition consisting of 2 parts by weight and 2 parts by weight of epoxy soybean oil is prepared, and air is forcibly mixed and dispersed into the composition using an oak mixer to form uniform and fine air bubbles. The volume was made into a sound-sealing volume, and this was applied to a thickness of 4 skins on release paper, and gelatinized by heating at a predetermined temperature shown in Table 1 using hot air for 5 minutes to produce a foam.

In order to check the foam retention or collapse properties of the foam sheet, we measured the thickness of the foam after heating, observed the appearance of the cells with the naked eye, and measured the tensile properties of the foam. It is listed in Table 1.

Measurement of physical properties was based on JIS K6767. For comparison, a case in which the crosslinking agent tolylene diisocyanate was not included (however, the volume after foaming was 3.4 times) was tested in the same manner and is also listed in Table 1. As is clear from the above results in Table 1, when a vinyl chloride copolymer with hydroxyl groups and its crosslinking agent were used as the vinyl chloride resin, no bubble collapse was observed at any temperature, and a dense and uniform cell structure was formed. A foam having the following properties is obtained.

However, those heated at a low temperature are inferior in terms of tensile strength and elongation, but a dramatic improvement is observed by heating to a temperature of 18,000 or higher. On the other hand, it can be seen that in the comparative example in which no crosslinking agent was used, the vinyl chloride copolymer was not crosslinked, so the cells collapsed, and the cell structure was also extremely unsatisfactory compared to that of the example. Comparative Example 2 Foaming was carried out in the same manner as in Example 1, except that the crosslinkable vinyl chloride copolymer of Example 1 was replaced with Paste Regiso (emulsion polymer product, P1500), which does not have crosslinking properties, and no crosslinking agent was used. The body was manufactured, the appearance of the collapsible cells, etc. of the bubbles was examined, and the second
Shown in the table.

Table 2 This comparative example reproduces the conventional method but increases the heating temperature.

From Experiment Nos. 5 and 6 in Table 2, it can be seen that when heated at high temperature by the conventional method, the bubbles easily collapse, resulting in a result similar to Comparative Example 1. Example 2, Comparative Example 3 In Example 1,
Same as Example 1 except that crosslinkable vinyl chloride copolymer ■ was changed to 'B}, parts by weight of DOP9 were changed to 90 parts by weight, and 5 parts by weight of the crosslinking agent tolylene diisocyanate were changed to 4 parts by weight of triethylenetetramine. I did the same.

Comparative Example 3 was conducted in the same manner as Example 2 except that triethylenetetramine was not used. The volume of these compositions after foaming was 3.1 times larger.

The heating conditions, physical property measurement results, etc. are shown in Table 3.

A vinyl chloride copolymer having a carboxyl group in Table 3 gives the same results as a copolymer having a hydroxyl group.

In the comparative example in which no crosslinking agent was used, the bubbles collapsed when the heating temperature was increased. Example 3 Vinyl chloride resin compositions having various compositions shown in Table 4 were tested in the same machine as in Example 1, and the results are also listed in Table 4.

Table 4 *1 Emulsion polymerized product P150o *2 Microsuspension polymerized product PIOOO From the above results, even if a fairly large amount of non-crosslinkable vinyl chloride resin is mixed, there is little collapse of bubbles during high temperature gelling, which is sufficient for the present invention. has achieved its purpose.

Claims (1)

[Scope of Claims] 1. A vinyl chloride copolymer having a hydroxyl group or a carboxyl group in its molecule, a crosslinking agent and a plasticizer each having at least two functional groups in each molecule that can react with a hydroxyl group or a carboxyl group. A vinyl chloride resin foam is produced by mechanically treating a sol-like vinyl chloride resin composition to uniformly mix gas into the composition, and then heating and gelling the composition. Manufacturing method. 2. The vinyl chloride resin composition according to claim 1, wherein the vinyl chloride resin composition comprises a vinyl chloride polymer or a copolymer of vinyl chloride and a comonomer copolymerizable therewith and containing no hydroxyl group or carboxyl group. Method for manufacturing resin foam.