JPS5827818B2 - Method for producing vinyl chloride synthetic resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl chloride synthetic resin foam having excellent rubber elasticity and a high expansion ratio.

More specifically, a foamed resin composition using a vinyl chloride polymer or copolymer that does not have active hydrogen in the molecule, a vinyl chloride copolymer that has active hydrogen in the molecule, and a thermoplastic polyurethane resin as a synthetic resin. The present invention relates to a method for producing a vinyl chloride-based synthetic resin foam having excellent rubber elasticity and a high expansion ratio by foaming it by normal pressure foaming.

In order to produce a vinyl chloride resin foam, a normal pressure foaming method or a pressure foaming method is usually applied as a foaming method.

In the normal pressure foaming method, a polyvinyl chloride-based foamed resin composition is usually molded at a temperature lower than the temperature at which the blowing agent decomposes, and then heated to a temperature higher than the decomposition temperature of the blowing agent. A foaming method is used.

On the other hand, in the pressure foaming method, the vinyl chloride foam resin composition is heated under pressure to a temperature higher than the decomposition temperature of the blowing agent to melt it, and the gas generated when the blowing agent decomposes is finely dispersed into the resin. A method is used in which the material is dispersed, then returned to normal pressure and foamed.

In normal pressure foaming of vinyl chloride foam resin compositions, continuous molding is possible using calender rolls or extruders, but foaming with a high expansion ratio (i.e. low density) using ordinary vinyl chloride polymers or copolymers is not possible. If you try to get a body,
There is a technical difficulty in that the cells in the resin become unevenly coarsened and further collapse, making it impossible to obtain the desired foam, and the reality is that only a foam with a low expansion ratio of 5 to 6 times can be produced at most. be.

In addition, thick foam (10
m/m thick foam is not comparable to polyurethane foam or polyolefin foam in terms of distortion or stiffness when compressed and cushioning properties.

In addition, in pressure foaming of a vinyl chloride foam resin composition, a foam with a high expansion ratio of 0.03 to 0.04 g/C111 can be obtained, but the foaming process is a batch process. Therefore, productivity is extremely low.

In order to solve these drawbacks in normal pressure foaming of vinyl chloride polymers, foaming is performed by blending crosslinking agents, blowing agents, plasticizers, etc. with vinyl chloride copolymers that have active hydrogen such as hydroxyl groups or carboxyl groups. However, this method requires precise control of the foam molding conditions. The reaction between the copolymer and the crosslinking agent proceeds extremely quickly, and has an extremely large effect on the melt viscosity during cell formation.For this reason, if foaming precedes crosslinking, cell roughness will occur, and conversely, crosslinking will be faster than foaming. It has been found that foaming is inhibited in advance and that it is therefore extremely difficult to scale a high expansion ratio foam having uniform and fine cells.

The inventor of the present invention has conducted extensive research in order to eliminate the drawbacks of sloping and provide a vinyl chloride resin foam with excellent rubber elasticity and a high expansion ratio. This discovery led to the completion of the present invention.

That is, the present invention uses 30 to 90 parts (by weight, the same applies hereinafter) of a vinyl chloride polymer or copolymer that does not have active hydrogen in the molecule, 5 to 40 parts of a vinyl chloride copolymer that has active hydrogen in the molecule, and A method for producing a vinyl chloride resin foam, which comprises adding a crosslinking agent, a blowing agent, a heat stabilizer, and a plasticizer to a resin composition consisting of 5 to 40 parts of a thermoplastic polyurethane resin, and foaming the mixture by normal pressure foaming. And,
By using a foamed resin composition made of the above-mentioned specific resin as a synthetic resin in normal pressure foaming, it is possible to produce a foam with a high expansion ratio by using a conventional vinyl chloride polymer or copolymer (i.e., containing active hydrogen in the molecule). As in the conventional method using vinyl chloride polymers or copolymers (without polyvinyl chloride), the cells in the foamed resin become uneven and coarse, and even collapse, resulting in the disadvantage that only inferior foams with low expansion ratios can be obtained. is completely eliminated, the cells in the foamed resin are formed finely and uniformly, and a foam with rubber elasticity and a high expansion ratio is produced, which is a very remarkable effect.

The vinyl chloride polymer or copolymer having no active hydrogen in the molecule used in the present invention can be obtained by a conventional suspension polymerization method, in which a vinyl chloride monomer or a vinyl chloride monomer and a vinyl thread having no active hydrogen are polymerized. Typical vinyl chloride polymers or vinyl chloride copolymers obtained by emulsion polymerization or other known polymerization methods are mentioned, and representative examples thereof include vinyl chloride homopolymers, vinyl chloride and Copolymers with vinyl esters (e.g. vinyl acetate, vinyl propionate, vinyl stearate, etc.), vinyl chloride and olefins (e.g. ethylene, propylene, butylene, styrene, etc.)
and copolymers of vinyl chloride and vinyl ethers (eg, stearyl vinyl ether, vinyl methyl ether, vinyl ethyl ether, etc.).

The average degree of polymerization of these vinyl chloride polymers or copolymers is in the range of 300 to 3,000, and preferably in the range of 700 to 1,900 from the viewpoint of workability.

In the method of the present invention, the proportion of vinyl chloride polymer or copolymer that does not have active hydrogen in the molecule is as follows:
As mentioned above, 5 to 40 parts of a vinyl chloride copolymer having active hydrogen in the molecule and 5 to 40 parts of a thermoplastic polyurethane resin.
40 parts to 30 to 90 parts is used, thereby producing a foam with uniform cell size and rubber elasticity even at high expansion ratios.

When the proportion of vinyl chloride polymer or copolymer that does not have active hydrogen in the molecule is more than 90 parts, roughness of cells occurs as the expansion ratio increases, and uniform cells are not obtained when the expansion ratio is 10 times or more. Moreover, it is not possible to obtain a foam with good rubber elasticity, and if it is less than 30 parts, the foaming ratio is small and it is economically disadvantageous, both of which are not preferable.

The vinyl chloride copolymer having active hydrogen in the molecule used in the present invention can be obtained by polymerizing a vinyl chloride monomer and a monomer having active hydrogen in the molecule, such as a hydroxyl group or a carboxyl group, using a conventional suspension polymerization method. Examples include those obtained by copolymerization using polymerization methods or solution polymerization methods. Representative examples include vinyl chloride monomer and 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate,
Hydroxyethyl meccrylate, 2-hydroxypropyl acrylate, 2-hydroxybrohil meccrylate, 3-chloro-2-hydroxypropyl meccrylate
1,3-hydroxybutyl acrylate, ethyl-2
-A vinyl chloride copolymer with hydroxyethyl fumarate, 3-hydroxybutyl vinyl ether, acrylic acid, methacrylic acid, monobutyl maleate, undecylenic acid, etc.

In addition, as for the vinyl chloride copolymer having active hydrogen in the molecule, the comonomer having active hydrogen such as hydroxyl group or carboxyl group in the molecule is 0.3 to 2.
A copolymerized product with a mole ratio of 0, preferably in the range of 0.5 to 10 molar ratio is used, and as a result, the melt viscosity at the time of cell formation is less affected by crosslinking, and it is highly foamable with rubber elasticity. The magnification of the foam can be changed.

When the copolymer composition ratio of monomers having active hydrogen such as hydroxyl groups and carboxyl groups in the molecule in the vinyl chloride copolymer having active hydrogen in the molecule is more than 20 molar ratio, the vinyl chloride polymer has excellent physical properties. is damaged and becomes 0 again,
When the molar ratio is less than 0), the reactivity with the crosslinking agent is insufficient, and therefore a foam with a high expansion ratio in which the cells have uniform rubber elasticity cannot be obtained, and both are unfavorable.

In addition to the vinyl chloride copolymers having active hydrogen such as hydroxyl groups and carboxyl groups in the molecule used in the present invention, vinyl chloride copolymers that do not have active hydrogen in the molecule can be chemically treated to It also includes vinyl chloride copolymers into which active hydrogen such as hydroxyl groups and carboxyl groups have been introduced.

Methods of chemically treating the vinyl chloride copolymer to introduce active hydrogen such as hydroxyl groups and carboxyl groups include, for example, a method of hydrolyzing a vinyl chloride-vinyl ester copolymer, a method of hydrolyzing a vinyl chloride-vinyl ester copolymer, and a method of hydrolyzing a vinyl chloride-vinyl ester copolymer. A method of hydrolyzing a copolymer of vinyl chloride and a vinyl monomer having an epoxy group, a method of ring-opening the epoxy group by acid treatment of a copolymer of vinyl chloride and a vinyl monomer having an epoxy group, and a method of hydrolyzing a copolymer of vinyl chloride and N-alkoxymethylacrylamide. The method of doing so is adopted.

In addition, in the method of the present invention, as the vinyl chloride copolymer having active hydrogen, a copolymer of vinyl chloride and N-alkoxymethylacrylamide, a copolymer of vinyl chloride and a vinyl monomer having an epoxy group, etc. It is also possible to use it as it is without any chemical treatment and to generate hydroxyl groups through a mechanochemical reaction during kneading and molding.

The average degree of polymerization of the vinyl chloride copolymer having active hydrogen in the molecule used in the present invention is 300 to 3000. Preferably, a range of 700 to 1900 is adopted.

When the average degree of polymerization of the polymer is greater than 3,000, the workability is poor, requiring high temperature or long kneading, thus inducing initial decomposition of the blowing agent;
If it is smaller, the expansion ratio and rubber elasticity will not be sufficiently high, and both are unfavorable.

The proportion of the vinyl chloride copolymer having active hydrogen in the molecule is 30 to 90 parts of the vinyl chloride polymer or copolymer having no active hydrogen in the molecule and 5 to 40 parts of the thermoplastic polyurethane resin, as described above. 5 to 40 parts per part of the foam is used, and as a result, even at high expansion ratios, a foam with uniform cell size and good rubber elasticity can be obtained.

When the usage ratio of the vinyl chloride copolymer having active hydrogen in the molecule is more than 40 parts with respect to the usage ratio of each of the above-mentioned components, the crosslinking property is too large and foaming tends to be inhibited, so that the foaming ratio decreases. When it is low, or less than 5 times, the rubber elasticity is poor due to insufficient crosslinking, and both are unfavorable.

The thermoplastic polyurethane resin used in the present invention is a linear polyurethane having active hydrogen in its molecule, for example, a difunctional polyurethane resin that reacts with a polyol and diisocyanate-1 under the conditions of a molar ratio of NC010I-I<1. Examples include those that have a hydroxyl group at the molecular end and can react with the crosslinking agent described below, and have an average molecular weight of 3,000 to 3,000.
300,000, preferably 10,000 to 100,000, and a Vicat softening point of 170°C or less is used.

The average molecular weight of the thermoplastic polyurethane resin used is 3
00000 and the Vicat softening point is higher than 170°C, the compatibility with the vinyl chloride polymer used as the resin composition is poor, and the average molecular weight is 30°C.
When it is smaller than 00, the rubber elasticity of the resulting foam is sufficiently high, and both are preferred.

In normal pressure foaming of a vinyl chloride foam resin composition, as mentioned above, if a normal vinyl chloride polymer is used as the vinyl chloride resin, a foam with a high expansion ratio cannot be obtained.
Furthermore, if a vinyl chloride copolymer having active hydrogen or a thermoplastic polyurethane resin is separately blended with a normal vinyl chloride polymer, the expansion ratio or cell condition may be slightly improved, but the There is no hope for improvement.

On the other hand, as in the method of the present invention, when a resin composition obtained by blending a vinyl chloride copolymer having active hydrogen and a thermoplastic polyurethane resin with a normal vinyl chloride polymer in a specific composition is used. The degree of crosslinking of the resin composition by the crosslinking agent described below is moderated to an extent suitable for obtaining a high expansion ratio by the gas generated by decomposition of the blowing agent, and furthermore, due to the crosslinking of these blended resins and the thermoplastic polyurethane resin, A foam with high expansion ratio and high rubber elasticity can be used.

In the method of the present invention, a vinyl chloride polymer or copolymer having no active hydrogen in the molecule is used as the resin composition.
Particularly preferred is one consisting of about 0 parts, about 20 parts of a vinyl chloride copolymer having active hydrogen in the molecule, and about 20 parts of a thermoplastic polyurethane resin, from the viewpoint of high foamability and rubber elasticity of the resulting foam.

The crosslinking agent used in the present invention is a vinyl chloride copolymer having active hydrogen in the molecule and a compound having two or more functional groups in the molecule that can react with the thermoplastic polyurethane resin. Compounds having isocyanate-1 groups, blocked incyanate groups, carboxyl groups, hydroxyl groups, epoxy groups, alkoxyalkylamino groups, hydroxyalkylamino groups, amine groups, alkyl mono- or di-substituted amino groups, and tribasic acid anhydrides. Things are used.

Typical examples include tolylene diisocyanate, diphenylmethane diisocyanate-1
・, polymethylene polyphenylisocyanate-1 or the above-mentioned polyisocyanate and a compound having at least bifunctional active hydrogen (trimethylolpropane, penquerythritol, glycerin, polyethylene glycol, polyte-1-ramethylene glycol) , polyethylene adipate, etc.), the inocyanate group of the polyisocyanate and the initial addition polymer is phenol,
Malonic acid diethyl ester, acetoacetic ester, acetoxime, acidic sodium sulfite, and other blocked isocyanates blocked with various masking agents, succinic acid, glutaric acid, adipic acid, phthalic acid, phthalic anhydride, cyclohexanedicarboxylic anhydride, triglyndyl Isocyanurate, epoxy resin, triethylenetetramine, methylolmelamine, butoxymethylmelamine, etc.
Particularly preferred are blocked incyanates.

The amount of these crosslinking agents used varies depending on the type of crosslinking agent used and the resin composition, but it is usually based on the total resin amount of the vinyl chloride copolymer with and without active hydrogen and the thermoplastic polyurethane resin in ioo parts. Against o, i~2
0 parts, preferably in the range of 0.5 to 10 parts.

When the amount of crosslinking agent used is more than 20 parts, crosslinking precedes foaming and tends to inhibit foaming, and the foaming ratio does not increase, and when it is less than 0 or 1 part, the foaming ratio is insufficient due to insufficient crosslinking. The cells become rough and the rubber elasticity becomes poor before they become large, both of which are undesirable.

As the blowing agent used in the present invention, ordinary blowing agents can be used as appropriate without any restrictions, such as azosica-bonamide, p,p'-oxybisbenzenesulfonylhydrazide, p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, Examples include 7'sulfonyl hydrazide, and azocabonamide is particularly preferably used.

The amount of the blowing agent used is in the range of 5 to 15 parts, preferably 8 to 12 parts, based on 100 parts of the resin composition. It will be done.

When the amount of blowing agent used is more than 15 parts, the amount of gas generated by the thermal decomposition of azosicabonamide is too large, so the cell size tends to become uneven, and when it is less than 5 parts, the foaming ratio is high. The amount of cracked gas necessary to obtain the foam becomes insufficient, which is not preferable.

Examples of the heat stabilizer used in the present invention include lead, zinc,
Examples include metal compounds such as cadmium, barium, sodium, potassium, calcium, lithium, and tin, in particular, composite stabilizers of these and organic stabilizers such as epoxy compounds, 1 to 5 parts per 100 parts of the resin composition,
Preferably, a range of 2 to 3 parts is employed.

If the amount of the heat stabilizer used is less than 1 part, the vinyl chloride copolymer will deteriorate due to heat, and if it is used more than 5 parts, it is uneconomical and undesirable.

A feature of the method of the present invention is that the crosslinking and foaming properties of the resin composition are not affected by the type of heat stabilizer used, and the foamed resin is mainly made of vinyl chloride polymers having active hydrogen such as hydroxyl groups and carboxyl groups. When used in
n-based, NaZn-based, K-Zn-based, LiBa-Zn-based, L
Most heat stabilizers such as i-CaBa type can be used, and therefore the conditions for producing foams with high expansion ratios are expanded, which is industrially preferable.

Examples of the plasticizer used in the present invention include dioctyl slate, dibutyl slate, dinonyl phthalate-1,
phthalic acid diesters such as dioctyl adipate, aliphatic dibasic acid esters such as dioctyl sebaque-1,
Examples include phosphoric acid triesters such as tricresyl phosphate and I-lyoctyl phosphate, epoxy plasticizers such as epoxidized soybean oil, and polyester plasticizers such as polyethylene adipate, based on 100 parts of the resin composition. 40-120 parts, preferably 50-9
A range of 0 parts is adopted.

When the amount of plasticizer used is outside the above range, a foam with uniform cell size and a high expansion ratio can be obtained, but the rubber elasticity tends to decrease, which is not preferable.

In the method of the present invention, a foamed resin composition in which a specific crosslinking agent, a blowing agent, a heat stabilizer, and a plasticizer are blended into a specific resin composition is foamed at normal pressure. Coloring agents such as organic dyes, organic pigments, and inorganic pigments may be appropriately blended as required.

To carry out the method of the present invention, first, the specific resin components, crosslinking agents, heat stabilizers, plasticizers, and other additives are mixed using a ribbon blender, pickler, Henschel mixer, etc., and then mixed using a mill roll or Banbury mixer. After kneading with etc., feeding it to a calendar roll or extruder and forming it into a sheet at a temperature below the decomposition temperature of the blowing agent, 1
It is heated at a temperature of about 80 to 250°C for about 30 seconds to 4 minutes to decompose the foaming agent and form a foam.

As described above, in the method of the present invention, the problems in conventional pressureless foaming of vinyl chloride-based foamed resin compositions are completely resolved, and the cells are uniform and fine even at a foaming ratio of 10 times or more. Furthermore, it is possible to easily and reliably produce a foam with high expansion ratio and high rubber elasticity without residual distortion due to compression, which is extremely useful industrially.

The resulting foam has rubber elasticity, so it is expected to be used as cushioning materials, cushioning materials, and flotation materials.Furthermore, since it has the properties of polyurethane resin, it has better cold resistance and oil resistance than ordinary vinyl chloride foam. It has excellent wear resistance and is extremely useful.

Next, the method of the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited only to these Examples.

Example 1 The resin components and additives shown in Table 1 were kneaded at 150°C for 10 minutes using two rolls with a diameter of 10 inches, and the mixture was kneaded to a thickness of 1.
．． It was made into a 0 mm foamable resin sheet.

This sheet was heated in an open oven heated to 220° C. for 2 minutes to cause foaming.

The foaming ratio, cell state compression hardness, and compression elasticity of the obtained foamed sheet were measured.

The measurement results are shown in Table 1.

Note that the physical properties were measured by the following method.

Foaming ratio 2 After foaming 0 Foaming'-to 0 Thickness (times) Thickness of foamed resin sheet before foaming Cell condition Marked with 20 means the cell diameter is 0.3 rrm or less,
and uniform. Δ indicates that the cells are partially destroyed. × indicates that the cells are severely rough, the cell diameter is uneven, and there are pores of 3 mm or more. Compression hardness: According to ASTM D1565. Thickness: 6.
This is the calculated value of the stress when a foam of 5 mm or more is compressed by 25 cycles at a compression speed of 15 mm 1'min and left to stand still for 60 seconds (number of tests = 3).Compression elasticity: Apply about 90 cycles of finger pressure to the center of the foam, Evaluate based on the state of recovery of the foam after pressure removal. ○ indicates that the foam recovers immediately after pressure is removed, and no trace of finger pressure remains. Δ indicates that there are still marks of finger pressure after pressure is removed, but it recovers 3 minutes after pressure is removed. Items marked with an "X" are those in which a finger pressure mark remains after the pressure is removed and does not recover after 3 minutes after the pressure is removed.For comparison, the resin components and additives shown in Table 1 are kneaded and foamed in the same manner as above. A synthetic resin sheet was prepared and then foamed.

The physical properties of the gill-shaped foam sheet were measured in the same manner as described above.

The measurement results are shown in Table 1. From Table 1, the foams obtained by the method of the present invention are comparative examples (those using a vinyl chloride polymer alone that does not have active hydrogen in the molecule, or those in which the vinyl chloride polymer has active hydrogen in the molecule). Compared to foams obtained using vinyl chloride-based copolymers with Moreover, it is clear that it is only elastic.

Examples 2-3 As shown in Table 2, the resin components and additives were
The mixture was kneaded using two inch rolls to form a foamable resin sheet with a thickness of 1.0 mm.

This sheet was heated in an open oven heated to 220° C. for 2 minutes to cause foaming.

The physical properties of the obtained foamed sheet were measured in the same manner as in Example 1.

The measurement results are shown in Table 2. For comparison, the second
As shown in the table, resin components and additives were kneaded in the same manner as described above to prepare a foamable resin sheet, which was then foamed.

The physical properties of the obtained foamed sheet were measured in the same manner as described above.

The measurement results are shown in Table 2. Table 2 shows that the foam obtained by the method of the present invention has a larger expansion ratio of 10 times or more than the foam obtained by the comparative example, has uniform and fine cells, and has good elasticity. It is clear that the

In addition, the method of the present invention can produce a highly elastic foam with a high expansion ratio even when kneaded under mixed conditions at low or high temperatures, and can be produced under a wide range of foam production conditions, which is extremely advantageous industrially.

Examples 4 to 7 As shown in Table 3, the resin components and additives were prepared in Example 1.
A foamable resin sheet was prepared by kneading in the same manner as above, and then foamed.

The physical properties of the obtained foamed sheet were measured in the same manner as in Example 1.

The measurement results are shown in Table 3.

For comparison, a foamable resin sheet was prepared by kneading resin components and additives as shown in Table 3 in the same manner as described above, and then foamed.

The physical properties of the obtained foamed sheet were measured in the same manner as described above.

The measurement results are shown in Table 3. Table 3 shows that the foam obtained by the method of the present invention has a larger expansion ratio of 10 times or more than the foam obtained by the comparative example, has uniform and fine cells, and has good elasticity. It is clear that it is something that will stop.

The foam obtained in Example 6 is particularly preferable in terms of expansion ratio and elasticity.

Claims (1)

[Scope of Claims] 1. 30 to 90 parts by weight of a vinyl chloride polymer or copolymer having no active hydrogen in the molecule, 5 to 40 parts by weight of a vinyl chloride copolymer having active hydrogen in the molecule, and thermoplastic A method for producing a vinyl chloride synthetic resin foam, which comprises blending a crosslinking agent, a blowing agent, a heat stabilizer, and a plasticizer with a resin composition consisting of 5 to 40 parts by weight of a polyurethane resin, and foaming the mixture by normal pressure foaming. . 2. The manufacturing method according to claim 1, wherein the vinyl chloride copolymer having active hydrogen in the molecule is a vinyl chloride copolymer having a hydroxyl group or a carboxyl group in the molecule. 3. The manufacturing method according to claim 1, wherein the thermoplastic polyurethane resin is a linear polyurethane having active hydrogen and capable of reacting with a crosslinking agent. 4. The manufacturing method according to claim 1, wherein the thermoplastic polyurethane is composed of a bifunctional polyol and a diisocyanate and has a hydroxyl group at the end of the molecule. 5 The crosslinking agent has two functional groups in the molecule that can react with active hydrogen.
2. The manufacturing method according to claim 1, wherein the manufacturing method has at least one of the following.