JPS6220220B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel vinyl chloride foamable resin composition. More specifically, the present invention has a vinyl chloride polymer or a vinyl chloride copolymer as a main component,
The cell structure of the foam is dense and uniform even when foamed at normal pressure using a calendar, etc., and it has closed cells with excellent compression recovery even when foamed at a high ratio, and has rubber elasticity, heat resistance, and chemical resistance. This invention relates to a polyvinyl chloride foamable resin composition that provides a foam with excellent chemical properties. In order to produce a vinyl chloride resin foam, a normal pressure foaming method or a pressure foaming method is usually employed as a foaming method. In the normal pressure foaming method, a vinyl chloride foamable 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 method is used in which foaming is performed using gas generated by decomposition of a foaming agent. 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-based foamable resin compositions, continuous molding is possible using calender rolls or extruders, but it is possible to use ordinary vinyl chloride polymers or copolymers to achieve high expansion ratios (i.e., low density). However, if you try to obtain a foam with a low foaming rate of 5 to 6 times, there is a technical difficulty in that the cells in the resin become unevenly coarsened and even collapse, making it impossible to obtain the desired foam. The reality is that only foam with a certain magnification can be obtained. Also, thick foam (10m/m thick foam) can be obtained by this normal pressure foaming.
When compressed, distortion remains, and its cushioning properties are not comparable to polyurethane foam or polyolefin foam. On the other hand, in pressure foaming of polyvinyl chloride-based foamable resin compositions, foams with rubber elasticity and extremely high expansion ratios with densities of 0.03 to 0.15 g/cm ³ can be obtained. The heat resistance and chemical resistance expected of vinyl are extremely low. In order to solve the above-mentioned drawbacks in normal pressure foaming and process foaming of vinyl chloride polymers, crosslinking agents, blowing agents, plasticizers, etc. are added to vinyl chloride copolymers containing active hydrogen such as hydroxyl groups or carboxyl groups. A method has been proposed in which foams are produced by blending, but this method requires precise control of foam molding conditions, since active hydrogen (i.e., hydrogen from hydroxyl groups or carboxyl groups) is generated near the decomposition temperature of the blowing agent. The reaction between the vinyl chloride copolymer having a It has been found that when crosslinking precedes foaming, foaming is inhibited, and it is therefore extremely difficult to obtain a foam with uniform and fine cells and a high expansion ratio. The present inventors have eliminated the above-mentioned drawbacks, and the rubber elasticity
As a result of intensive research to provide a vinyl chloride resin foam with high expansion ratio and excellent heat resistance and chemical resistance, we have developed (A) vinyl chloride polymer or copolymer.
100 parts (by weight, same below), (B) acrylic rubber 0.5
When a vinyl chloride foamable resin composition consisting of ~30 parts and (C) crosslinking agent 0.1 to 5 parts, a blowing agent, a stabilizer, and a plasticizer is used to produce a foam with a high expansion ratio, ordinary vinyl chloride polymer This completely eliminates the drawback that conventional methods using polymers or copolymers can only produce foams with a low expansion ratio due to the cells (bubbles) in the foam becoming uneven, coarse, or collapsing. The present invention was completed by discovering the new fact that a high expansion ratio foam with fine and uniform cells and excellent rubber elasticity, heat resistance, and chemical resistance can be obtained. . The component (A) used in the present invention, that is, the vinyl chloride polymer or copolymer, can be prepared by a conventional suspension polymerization method, an emulsion polymerization method, or a vinyl chloride monomer alone or a vinyl monomer copolymerizable with the vinyl chloride monomer. All other vinyl chloride polymers or vinyl chloride copolymers obtained by known polymerization methods are included. Examples of the vinyl monomer to be copolymerized with the vinyl chloride monomer include vinyl esters (such as vinyl acetate, vinyl propionate, vinyl stearate, etc.),
Olefins (e.g. ethylene, propylene, butylene, styrene, etc.), vinyl ethers (e.g. stearin vinyl ether, vinyl methyl ether, 3-hydroxybutyl vinyl ether, etc.), acrylic or methacrylic acid, or derivatives thereof (e.g. ethyl acrylate,
Ethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 3-
chloro-2-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, etc.),
Acrylamide or its derivatives (e.g. N
-methylol acrylamide, N-butoxymethyl acrylamide, etc.), vinyl carboxylic acids (e.g. undecylenic acid, etc.), maleic acid or fumaric acid, or derivatives thereof (e.g. monobutyl maleate, ethyl-2-hydroxyethyl fumarate, etc.). One or more of these vinyl monomers can be copolymerized with a vinyl chloride monomer. Copolymers obtained by further chemical treatment of vinyl chloride copolymers, such as terpolymers obtained by partially saponifying copolymers of vinyl chloride and vinyl acetate, can also be suitably used. Furthermore, one or a mixture of two or more vinyl chloride polymers or copolymers may be used. These vinyl chloride polymers or copolymers can be used with an average degree of polymerization in the range of 300 to 3,000, but from the viewpoint of workability, it is preferably in the range of 700 to 1,900. When the average degree of polymerization is greater than 3000, high temperature or long kneading is required,
Further, initial decomposition of the blowing agent is induced, and if the average polymer is less than 300, a sufficiently high expansion ratio and rubber elasticity cannot be obtained, both of which are undesirable. As the component B in the present invention, that is, the acrylic rubber, any elastic body containing an acrylic acid alkyl ester as a main component and a copolymer with a subcomponent having an active group serving as a crosslinking point can be used. For example, one of the alkyl acrylates such as ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.
The main component is allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate,
Examples include copolymers with subcomponents having active groups that serve as crosslinking points, such as -chloroethyl vinyl ether, and particularly preferred are acrylic rubbers having epoxy groups or hydroxyl groups as active groups. Acrylic rubber is generally produced by salting out and drying an emulsion polymer obtained by emulsion polymerization, and is usually obtained in bulk form, but it can also be produced by suspension polymerization. Furthermore, unlike general-purpose diolefin-based synthetic rubber, acrylic rubber has good compatibility with vinyl chloride-based resins and excellent heat resistance. Even when added in a small amount of about 1 part per 100 parts of the resin, it promotes the gelation of the vinyl chloride resin and also has the effect of controlling the air bubbles in the foam, making it extremely useful as a processing aid. The blending ratio of such acrylic rubber is 0.5 to 30 parts per 100 parts of component (A), especially 1 to 1, in order to impart excellent crosslinking properties to the resulting resin composition and to obtain a foam with excellent rubber elasticity. Preferably 15 parts. When the blending ratio of acrylic rubber is smaller than the above range, the rubber elasticity of the foam obtained by high-magnification foaming is poor, and when it is larger than the above range, a foam with good rubber elasticity is obtained. However, it is uneconomical because it requires a large amount of expensive acrylic rubber, and it also impedes roll processability, which is an advantage of vinyl chloride resins, which is not preferable. However, in the present invention, although acrylic rubber is used in an extremely small amount of only 1 to 5 parts, it can exhibit excellent crosslinking properties and rubber elasticity, and as mentioned above, it can improve the processability of vinyl chloride resin. Coupled with the advantage that it can also be improved, its industrial value is extremely great. The above-mentioned component (C), that is, the crosslinking agent, used in the present invention includes compounds having two or more functional groups in the molecule that can react with the active groups of acrylic rubber, such as isocyanate groups, blocked isocyanate groups, and carboxyl groups in the molecule. Compounds having a hydroxyl group, an epoxy group, an alkoxyalkylamino group, a hydroxyalkylamino group, an amino group, an alkyl mono- or di-substituted amino group, dibasic acid anhydrides, and the like are used. Typical examples thereof include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, or a compound having at least bifunctional active hydrogen in combination with the polyisocyanate (for example, trimethylolpropane, pentaerythritol, (glycerin, polyethylene glycol, polytetramethylene glycol, polyethylene adipate, etc.), and the isocyanate groups of the polyisocyanate and the initial addition polymer are combined with phenol, diethyl malonate, acetoacetate, etc. , acetoxime, acidic sodium sulfite, and other blocked isocyanates blocked with various masking agents, succinic acid, glutaric acid,
Examples include adipic acid, phthalic acid, phthalic anhydride, cyclohexanedicarboxylic anhydride, triglycidyl isocyanurate, epoxy resin, triethylenetetramine, methylolmelamine, butoxymethylmelamine, and blocked isocyanates are particularly preferred. The amount of these crosslinking agents used varies depending on the type of crosslinking agent used and the resin composition, but the amount of the (A) component 100
If the amount of crosslinking agent used is more than 5 parts, it is economically disadvantageous, but the effect of improving foamability and elasticity is less. If it is too small, foaming may be inhibited due to crosslinking, and if it is less than 0.1 part, cells tend to become rough due to lack of crosslinking, and rubber elasticity is poor, making it impossible to obtain a product with good recovery properties and feel. Both are unfavorable. The blowing agent used in the present invention is not limited to ordinary decomposable blowing agents, and may be used as necessary, such as azodicarbonamide,
Examples include p.p'-oxybisbenzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, and benzenesulfonyl hydrazide, and these may be used alone or in combination of two or more. In particular, azodicarbonamide is preferably used. The amount of blowing agent used is component (A).
A range of 1 to 20 parts, preferably 2 to 15 parts per 100 parts is adopted, which results in a foaming ratio of 2 to 20 with a dense cell structure, uniform foaming properties, and excellent feel.
You can get about twice the amount of foam. The modification effect of the foam using the above-mentioned (B) component and (C) component in the present invention is particularly remarkable in a high-expansion foam with a foaming ratio of 7 times or more, and the (A) component alone or the (A) component ) added as a modifier to component (B)
Even when either component or (C) component is missing, or when either of them is out of the above range in the blending ratio, the resulting foam will have a uniformly dense cell structure, compression recovery, rebound resilience, and heat resistance. , it is not possible to significantly improve chemical resistance. The reason for this is not clear, but the (B) and (C) components are uniformly dispersed and mixed together with other ingredients in the (A) component, and this ( B) and (C)
Because the components are partially crosslinked, the viscosity of the resin composition becomes slightly higher when foamed at high temperatures compared to normal non-crosslinked products, and due to the excellent stretchability and miscibility of acrylic rubber, As uniform partial crosslinking progresses and the cell film becomes tougher, even when made into a high-magnification foam, the cells remain closed and uniformly dense, and the physical property shows a rubber-like compression recovery with appropriate elasticity. It is thought that a foam with excellent elasticity, rebound, heat resistance, and chemical resistance can be obtained. Examples of the stabilizer used in the present invention include lead,
These include metal compounds such as zinc, cadmium, barium, sodium, potassium, calcium, lithium, and tin, as well as composite stabilizers of these compounds and organic stabilizers such as epoxy compounds.
A range of 1 to 5 parts, preferably 2 to 3 parts per 100 parts is employed. When the amount of the stabilizer used is less than 1 part, the vinyl chloride copolymer tends to deteriorate due to heat, and when it is used more than 5 parts, it is uneconomical and undesirable. Examples of the plasticizer used in the present invention include phthalic acid diesters such as dioctyl phthalate, dibutyl phthalate, and dinonyl phthalate, aliphatic dibasic acid esters such as dioctyl adipate and dioctyl sebacate, tricresyl phosphate, and trioctyl phosphate. Phosphate triesters such as epoxy plasticizers such as epoxidized soybean oil, polyester plasticizers such as polyethylene adipate, diallyl phthalate, ethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, trimethylolpropane trimethacrylate reactive plasticizers, such as
Flame-retardant plasticizers such as triβ-chloroethyl phosphate and chlorinated paraffin can be used alone or in combination of two or more. The amount of these plasticizers used is per 100 parts of component A.
A range of 40 to 180 parts, preferably 50 to 150 parts is employed. 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 foamable resin composition prepared by blending a specific crosslinking agent, a commonly used blowing agent, a stabilizer, and a plasticizer with a specific resin composition is heated and foamed. Depending on the purpose, other coloring agents such as organic dyes, organic pigments, and inorganic pigments, fillers such as calcium carbonate, aluminum hydroxide, clay, and talc, as well as powder type chlorinated paraffin,
A flame retardant such as antimony trioxide may be added as appropriate. The following methods are usually employed to carry out the method of the present invention, but it goes without saying that other methods may also be employed. (1) The above-mentioned specific resin component, crosslinking agent, stabilizer, plasticizer, and other additives are mixed using a ribbon blender, crusher, Henschel mixer, etc., kneaded using a mill roll or Banbury mixer, and then calender roll. Alternatively, it is supplied to an extruder and formed into a sheet at a temperature below the decomposition temperature of the blowing agent, and then heated at a temperature of about 180 to 250°C for about 30 seconds to 4 minutes to decompose the blowing agent and form a foam. (2) Mix the specific resin component, crosslinking agent, stabilizer, plasticizer, and other additives in the same manner as in (1) above, and use a mill roll, Banbury mixer, extruder, etc. to heat the mixture to below the decomposition temperature of the blowing agent. After kneading at a temperature of 70 to 100 of the mold capacity, the
% ratio, apply an external pressure that can withstand the decomposition pressure of the blowing agent to the mold, and heat it at a temperature of about 160 to 200℃ for 5 to 30 minutes.
Heat for a minute to allow the blowing agent to decompose. The resin composition is then cooled to 20 to 60°C under external pressure, taken out from the mold, and expanded in a heating furnace heated to 90 to 150°C to form a foam. (3) Component (B), that is, acrylic rubber, in xylene,
It is dissolved in organic solvents such as toluene and benzene, vinyl chloride plasticizers such as dioctyl phthalate and dibutyl phthalate, or process oil for rubber, and then mixed with other specific resin components, crosslinking agents, stabilizers, plasticizers, etc. Mix with a ribbon mixer, crusher, Henschel mixer, etc., then uniformly mix with a paint mill, homogenizer, etc., and apply it to base materials such as release paper, flame-retardant paper for wallpaper, woven fabric, etc. with a knife coater, Apply it to the desired thickness using a roll coater, heat it for 30 seconds to 3 minutes at a temperature of 120 to 160°C at which the foaming agent does not decompose, and then gel it at 180 to 160°C.
Heat at a temperature of about 250°C for 30 seconds to 4 minutes to decompose the foaming agent and form a foam. As mentioned above, in the method of the present invention,
The problems associated with normal pressure foaming of conventional vinyl chloride foam resin compositions have been completely resolved, and the cells are uniform and fine even when the expansion ratio is 10 times or more, and there is no residual distortion due to compression, making it rubber elastic and heat resistant. sex,
A foam with excellent chemical resistance and a high expansion ratio can be easily and reliably produced, and even in pressure foaming, there is no residual distortion due to compression and the rubber elasticity is improved. It is possible to produce a foam with excellent heat resistance and chemical resistance and a high expansion ratio, making it extremely useful industrially. The resulting foam has rubber elasticity, heat resistance, and chemical resistance that cannot be obtained with ordinary vinyl chloride foam, making it ideal for use as cushioning materials, cushioning materials, flotation materials, and insulation materials. It can be used for very good purposes such as foamed leather for bags, clothing, and furniture without requiring high-magnification foaming, and its industrial value is extremely high. Next, the resin composition of the present invention will be explained with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited to these Examples. The methods for measuring and evaluating the expansion ratio, cell state, compression recovery, heat resistance, and chemical resistance in the Examples and Comparative Examples below are as follows. (1) Expansion ratio In case of normal pressure foamed sheet form Expansion ratio = Thickness of foamed sheet after foaming / Thickness of resin sheet before foaming (times) In case of pressurized foamed block form Expansion ratio = Thickness of foamed sheet before foaming Resin composition density/foam density after foaming (double) (2) Cell condition 〇: Uniform cell diameter of 0.3 mm or less △: Some cells with a cell diameter of 0.3 mm or more are mixed,
Slightly uneven ×: Noticeable roughness (many cells have a diameter of 1 mm or more) and unevenness (3) Compression recovery property The center of the foam was compressed by about 90% with fingers, and the recovery state after the pressure was removed was evaluated. . 〇: Immediate recovery after decompression, and no trace of compression remained. △: After decompression, traces of compression remained, but recovered within 10 seconds. ×: After decompression, traces of compression remained and did not recover even after 10 seconds had passed. (4) Heat resistance The foam was cut into 3 x 3 cm squares and left in an oven at 200°C for 5 minutes, after which changes in shape were examined. ○: Almost no change in shape was observed. Δ: The shape was slightly distorted. ×: The shape was completely destroyed. (5) Chemical resistance A 3 x 3 cm square foam was placed in a 200 ml beaker, 50 ml of tetrahydrofuran was poured into it, and the state of dissolution of the foam was observed while shaking gently. ○: No dissolution was observed even after 30 minutes, and almost no change in shape was observed. △: It did not dissolve even after 10 minutes had passed, but the shape was distorted. ×: Completely dissolved within 10 minutes. Examples 1 to 5 and Comparative Example 1 The resin components and additives shown in Table 1 were kneaded using two rolls at 145°C for 7 minutes to obtain each foamable resin sheet with a thickness of 0.7 mm. Place these sheets in the oven at 220℃ for 2 minutes.
Heat and foam for ~3 minutes. The foaming ratio, cell condition, and
Compression recovery, heat resistance, and chemical resistance were each investigated. The results are shown in Table 1.

[Table] From the results in Table 1, it can be seen that the foam obtained from the ordinary foamable resin composition (Comparative Example 1) was
At a foaming ratio of 7.6 times (heated for 2 minutes), cell roughness was already noticeable and the compression recovery properties were only poor, whereas in Examples 1 to 5, 1 to 30 parts of acrylic rubber and 4 parts of crosslinking agent were used. By incorporating , the cell state was dense and uniform even when the expansion ratio was increased to 10 times or more, and the cell state was excellent in compression recovery, heat resistance, and chemical resistance. Examples 6 to 11 and Comparative Example 2 The resin components and additives shown in Table 2 were used in Example 1.
- Knead and form a sheet in the same manner as in 5, and heat at 220°C.
The mixture was heated in an oven for 2 minutes and 30 seconds to 3 minutes to foam. The expansion ratio and physical properties of each foam obtained were
Shown in the table.

【table】

[Table] From the results in Table 2, the compounding effect of acrylic rubber is
It can be seen that it can already be seen from 0.5 parts. If acrylic rubber is not added (Comparative Example 2), it is not possible to obtain a foam with sufficiently satisfactory cell state and compression recovery properties. Examples 12 to 18 and Comparative Example 3 The resin components and additives shown in Table 3 were kneaded and formed into a sheet in the same manner as in Examples 1 to 5, and
It was heated in an oven at 220°C for 2 minutes and 30 seconds to 3 minutes to foam. The expansion ratio and physical properties of each foam obtained were
Shown in the table.

【table】

[Table] From the results in Table 3, any of polyisocyanate, blocked isocyanate, epoxy resin, and butyl ether melamine resin can be used as the crosslinking agent, and the amount added is preferably 0.1 to 5 parts. I understand that. It is understood that isocyanate-based crosslinking agents are particularly preferred from the viewpoint of compression recovery properties. Furthermore, if a crosslinking agent is not added (Comparative Example 3), cell roughness will already occur after 6 times the foaming as in Comparative Example 1, and it will be impossible to achieve a higher expansion ratio, and the compression recovery will be poor. . Examples 19-21 and Comparative Examples 4-5 The resin components and additives shown in Table 4 were mixed uniformly in a homomixer and coated on release paper (surface treated with silicone) to a thickness of 0.5 mm using a knife coater. Thereafter, it was heated in an oven at 150°C for 1 minute to gel, and further heated in an oven at 220°C for 1 minute to foam, thereby obtaining a foam. In Table 3, the acrylic rubber used was one previously dissolved in a plasticizer (dibutyl phthalate) at a concentration of 15% by weight. Table 4 shows the expansion ratio and physical properties of each foam obtained.

【table】

[Table] Examples 22 to 24 and Comparative Examples 6 to 7 The resin components and additives shown in Table 5 were mixed, kneaded, and gelled for 10 minutes using a mixing roll heated to 140°C. It was taken out as a sheet of mm. After filling 110 g of this material into a chrome-plated iron mold with an internal capacity of 10 x 10 x 1 cm, the mold was placed in a steam-heated 50-ton press with a hot plate area of 33 x 33 cm. steam pressure of 7Kg/ ^cm2 by applying an external pressure of 100Kg per unit area.
The mixture was heated for 10 minutes at a temperature of 1, and foamed. Next, the steam was discharged, tap water with a water temperature of 17°C was introduced, the mold was cooled for 7 minutes, the pressure outside the press was removed, the foam was removed from the mold, and the foam was introduced into a hot air circulation oven at 100°C and heated for 20 minutes. The foamable resin composition was expanded. Table 5 shows the expansion ratio and physical properties of the obtained foam.

【table】

[Table] From the results in Table 5, it can be seen that even in pressure foaming, the foamable resin composition of the present invention is greatly improved in heat resistance and chemical resistance, and further improved in compression recovery.

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a vinyl chloride polymer or copolymer, (B) 0.5 to 30 parts by weight of acrylic rubber, and (C) 0.1 to 5 parts by weight of a crosslinking agent, as well as a blowing agent and a stabilizer. and a vinyl chloride foamable resin composition comprising a plasticizer. 2. The resin composition according to claim 1, wherein the acrylic rubber is an elastic body containing an acrylic acid alkyl ester as a main component, and is a copolymer with a subcomponent having an active group serving as a crosslinking point. 3. The resin composition according to claim 1, wherein the crosslinking agent has at least two functional groups in the molecule that can react with the active groups of the acrylic rubber.