JP2019151709A - Resin composition for foamed resin sheets, foamed resin sheet, laminated sheet, and method for producing foamed resin sheet - Google Patents

Abstract

To provide a foamed resin sheet having excellent moldability, heat insulation performance, lightness in weight, mechanical characteristics and flame retardancy, and a resin composition for foamed resin sheets for use therein.SOLUTION: A resin composition for foamed resin sheets contains, based on a polyvinyl chloride resin (A) 100 pts.mass, a plasticizer (B) 40-75 pts.mass, tin acid zinc (C) 5-20 pts.mass, and a thermally expandable microcapsule (D) 1-20 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition for a foamed resin sheet, a foamed resin sheet, a laminated sheet including the foamed resin sheet, and a method for producing the foamed resin sheet.

  Foamed resin sheets are widely used in applications that require light weight, heat insulation, sound insulation, vibration isolation, and the like. For example, foamed resin sheets are used for flooring materials, wall materials, doors, window frames and the like in building materials for the purpose of sound insulation, heat insulation, vibration isolation, and the like.

  As a general method for producing a foamed resin sheet, a method is used in which a chemical foaming agent is added to a thermoplastic resin serving as a matrix, and the foaming agent is decomposed and vaporized during heat molding to obtain a foam. However, the method using a chemical foaming agent has a problem that it is difficult to control the size and distribution of pores.

  Furthermore, when using a sheet | seat as building materials, such as a flooring, a wall material, a door, and a window frame, in addition to the above-mentioned performance, having a flame retardance is requested | required.

  As means for solving the above problem, for example, in Patent Document 1, a thermally expandable microcapsule is blended with a thermoplastic resin, and the thermally expandable microcapsule is expanded by kneading and melting heat by extrusion molding or injection molding. A foam molding method characterized by molding is disclosed. Patent Document 2 discloses a molding method characterized by blending a heat-expandable microcapsule with a soft vinyl chloride resin composition and extrusion-molding at or above the expansion start temperature of the heat-expandable microcapsule. . Patent Document 3 discloses a vinyl chloride resin composition comprising a vinyl chloride resin and a thermally expandable microcapsule and a perchlorate compound. Further, Patent Document 4 discloses a low smoke / low toxicity flame retardant vinyl chloride compound containing vinyl chloride resin, plasticizer, stabilizer, and zinc stannate as a flame retardant.

Japanese Patent Laid-Open No. 10-152575 Japanese Patent Laid-Open No. 11-060868 JP 2000-290418 A Japanese Patent Laid-Open No. 7-278386

  The foamed resin sheets of Patent Documents 1 to 3 have room for improvement in heat insulation and light weight, and do not have flame retardancy. Although the film using the compound described in Patent Document 4 has flame retardancy, it is not a foamed resin, so that it is insufficient in lightness and heat insulation.

  In view of such problems of the prior art, the present invention provides a foamed resin sheet excellent in heat insulation, lightness, mechanical properties and flame retardancy, a resin composition for foamed resin sheet used therein, and a laminated sheet including the foamed resin sheet And it aims at providing the manufacturing method of a foamed resin sheet.

  As a result of diligent investigations, the present inventors have found that a resin composition in which a predetermined amount of a plasticizer, zinc stannate, and thermal expansion microcapsules are added to a polyvinyl chloride resin, and the resin composition is thermoformed. The present inventors have found that a foamed resin sheet, a laminated sheet containing a foamed resin sheet, and a method for producing a foamed resin sheet can solve the above problems, and have reached the present invention described below.

  1st this invention is 40-75 mass parts of plasticizers (B), 5-20 mass parts of zinc stannate (C), and a thermally expansible micro | micron | matter with respect to 100 mass parts of polyvinyl chloride-type resin (A). It is a resin composition for foamed resin sheets characterized by containing 1-20 mass parts of capsules (D).

  In the first aspect of the present invention, the zinc stannate is preferably zinc tin trioxide.

  1st this invention WHEREIN: Furthermore, it is preferable to contain 5-15 mass parts of metal hydroxides (E) with respect to 100 mass parts of said polyvinyl chloride-type resin (A).

  In the first invention, the plasticizer (B) is at least one selected from the group consisting of a phthalic acid plasticizer, a trimellitic acid plasticizer, a polyester plasticizer, and an adipic acid plasticizer. It is preferable.

  2nd this invention is a foamed resin sheet obtained by heat-molding the resin composition for foamed resin sheets of 1st this invention, Comprising: The said thermal expansion thermally expanded by the heat | fever applied in the said thermoforming This is a foamed resin sheet having microcapsules (D).

3rd this invention contains plasticizer (B) 40-75 mass parts and 5-20 mass parts of zinc stannate (C) with respect to 100 mass parts of polyvinyl chloride-type resin (A). The foamed resin sheet has closed cells due to the thermally expanded microcapsules (D) in the matrix and an apparent density of 0.1 to 0.85 g / cm ³ .

  In 3rd this invention, it is preferable that the closed cell resulting from a thermal expansion microcapsule (D) is a thermally expanded microcapsule.

  In the second and third aspects of the present invention, the tensile elongation at break measured in accordance with JIS K7127 is preferably 50% or more.

  In the second and third aspects of the present invention, the oxygen index is preferably 23% or more.

  In the second and third present inventions, the plasticizer (B) is a kind selected from the group consisting of a phthalic acid plasticizer, a trimellitic acid plasticizer, a polyester plasticizer, and an adipic acid plasticizer. The above is preferable.

  4th this invention is a laminated sheet containing at least 1 layer of the foamed resin sheet of 2nd and 3rd this invention.

  In the fourth aspect of the present invention, it is preferable to provide the foamed resin sheets of the second and third aspects of the present invention at least in the intermediate layer.

  5th this invention is equipped with the process of heat-molding the resin composition for foamed resin sheets of 1st this invention, The said thermal expansion microcapsule (D) is expanded with the heat | fever applied in the case of this thermoforming, It is a manufacturing method of a foamed resin sheet.

  ADVANTAGE OF THE INVENTION According to this invention, the foamed resin sheet which is excellent in a moldability, heat insulation, lightness, mechanical characteristics, and a flame retardance, the resin composition for foamed resin sheets used for this, the laminated sheet containing a foamed resin sheet, and foamed resin A sheet manufacturing method can be provided.

(A) is a scanning electron microscope image (SEM image) of the sheet obtained in Example 5, (b) is an SEM image of the sheet obtained in Example 6, and (c) is Comparative Example 2. It is a SEM image of the sheet | seat obtained by.

  Hereinafter, a foamed resin sheet as an example of an embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below. Unless otherwise specified, the notation “A to B” for numerical values A and B means “A to B”. In this notation, when a unit is attached to only the numerical value B, the unit is also applied to the numerical value A.

[Resin composition for foamed resin sheet]
The resin composition (resin composition for a foamed resin sheet) used for the foamed resin sheet of the present invention is composed of 40 to 75 parts by mass of a plasticizer (B), 100 parts by mass of a polyvinyl chloride resin (A), and stannic acid. It contains 5 to 20 parts by mass of zinc (C) and 1 to 20 parts by mass of thermally expandable microcapsules (D). Furthermore, it is preferable to contain 5-15 mass parts of metal hydroxides (E) with respect to 100 mass parts of the said polyvinyl chloride-type resin (A). Hereinafter, each component which comprises the resin composition for foamed resin sheets of this invention is demonstrated.

<Polyvinyl chloride resin (A)>
As the polyvinyl chloride resin (A) used in the present invention, a polyvinyl chloride resin having an arbitrary average degree of polymerization can be used. Preferably, the average degree of polymerization of the polyvinyl chloride resin (A) is 600 to 3,000. If the average degree of polymerization is 600 or more, sufficient mechanical strength can be obtained. On the other hand, if the average degree of polymerization exceeds 3,000, the mechanical properties are not improved and the impractical decrease in workability (fluidity) is impractical.

  Therefore, from such a viewpoint, the average degree of polymerization of the polyvinyl chloride resin (A) is more preferably 800 or more and 2,900 or less in the above-mentioned range, and among these, 900 or more and 2,800 are more preferable. More preferably, it is as follows.

  Polyvinyl chloride resin (A) includes polyvinyl chloride homopolymers (referred to as “polyvinyl chloride homopolymers”) and copolymers with monomers copolymerizable with polyvinyl chloride. (Hereinafter referred to as “polyvinyl chloride copolymer”), a graft copolymer obtained by graft copolymerization of vinyl chloride to a polymer other than this polyvinyl chloride copolymer (hereinafter referred to as polyvinyl chloride graft copolymer). Polymer) and the like.

  Since the mechanical properties of a polyvinyl chloride copolymer decrease as the content of constituent units other than polyvinyl chloride increases in the copolymer, the proportion of vinyl chloride in the polyvinyl chloride copolymer is reduced. It is preferable that it is 60-99 mass%.

  The polyvinyl chloride homopolymer and the polyvinyl chloride copolymer can be polymerized by an arbitrary method such as an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method and the like.

  Here, as the monomer copolymerizable with polyvinyl chloride, any monomer having a reactive double bond in the molecule may be used. For example, α-olefins such as propylene and butylene, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and cetyl vinyl ether, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, methyl acrylate, Esters of acrylic acid or methacrylic acid such as ethyl methacrylate and phenyl methacrylate, aromatic vinyls such as styrene and α-methylstyrene, vinyl halides such as vinylidene chloride and vinyl fluoride, N-phenylmaleimide, N N-substituted maleimides such as -cyclohexylmaleimide can be mentioned, and these can be used alone or in combination of two or more.

  As the polymer other than the polyvinyl chloride copolymer, any polymer capable of graft copolymerization with vinyl chloride may be used. For example, ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / carbon monoxide copolymer, ethylene / ethyl acrylate copolymer, ethylene / ethyl acrylate / carbon monoxide copolymer, ethylene / methyl methacrylate copolymer, ethylene -A propylene copolymer, an acrylonitrile butadiene copolymer, a polyurethane, chlorinated polyethylene, a chlorinated polypropylene etc. can be mentioned, These can be used individually or in combination of 2 or more types.

<Plasticizer (B)>
The resin composition for a foamed resin sheet of the present invention can improve the film forming property of the foamed resin sheet by containing the plasticizer (B).

  The plasticizer (B) that can be used in the present invention is not particularly limited, and a known plasticizer can be used. For example, di-n-butyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, dioctyl decyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, di-2-isophthalate Phthalic acid plasticizers such as ethylhexyl, adipic acid plasticizers such as adipic acid-2-ethylhexyl, di-2-decyl adipate, sebacic acid plasticizers such as dibutyl sebacate and 2-ethylhexyl sebacate, Trimellitic plasticizers such as tri-2-ethylhexyl meritate and trioctyl trimellitic acid, polyester plasticizers such as adipic acid polyester plasticizer and phthalic polyester plasticizer, terephthalic acid plasticizer, large epoxidation Bean oil, epoxidized linseed oil, epoxidized cottonseed oil, Epoxidized peanut oil, epoxidized safflower oil, epoxidized vegetable oils such as epoxidized grape seed oil (epoxy type plasticizer), and the like. These may be used alone or in combination.

Among them, the resin composition for a foamed resin sheet of the present invention uses one or more selected from the group consisting of a phthalic acid plasticizer, a trimellitic acid plasticizer, a polyester plasticizer, and an adipic acid plasticizer. It is preferable to do. By using the plasticizer, the dispersibility of the thermally expandable microcapsules in the resin composition for a foamed resin sheet is improved, the foamability of the produced foamed resin sheet is improved, and the appearance of the sheet is improved.
As the plasticizer, it is preferable to use a phthalic acid plasticizer which is economical and versatile and excellent in the effect of uniformly dispersing the thermally expandable microcapsules in the polyvinyl chloride resin. Examples of the phthalic acid plasticizer include dioctyl phthalate (DOP) and diisononyl phthalate (DINP). From the viewpoint of environmental compatibility, diisononyl phthalate (DINP) is used. It is preferable.

In the resin composition for a foamed resin sheet of the present invention, it is preferable that the plasticizer does not contain a phosphorus plasticizer. When the phosphorus plasticizer is included, the dispersibility of the thermally expandable microcapsules in the resin composition for the foamed resin sheet becomes poor, and the foamability of the produced foamed resin sheet and the appearance of the sheet become poor. There is.
Examples of phosphorus plasticizers include known aromatic phosphate ester flame retardants, such as tris (isopropylphenyl) phosphate, cresyl diphenyl phosphate, tricresyl phosphate, triphenyl phosphate, trixylenyl phosphate. 2-ethylhexyl diphenyl phosphate, 2-naphthyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate, and the like.

<Zinc stannate (C)>
The resin composition for foamed resin sheets of the present invention can impart flame retardancy to the resin composition for foamed resin sheets by containing zinc stannate (C).

  Examples of zinc stannate (C) include zinc tin oxide and zinc hexahydroxide. The decomposition temperature of zinc hexahydroxide zinc is about 200 ° C., which is close to the molding temperature of the foamed resin sheet, and may be decomposed during molding. On the other hand, the decomposition temperature of tin zinc trioxide is about 400 ° C., which is close to the actual combustion temperature. Therefore, the resin composition for foamed resin sheets of the present invention uses tin zinc trioxide, which is expected to have a more flame-retardant effect. It is preferable to do.

<Thermal expansion microcapsule (D)>
The thermal expansion microcapsule (D) used in the present invention has a shell made of acrylonitrile / methacrylonitrile / vinyl acetate copolymer and volatilization of butane, pentane, hexane, cyclohexane, toluene, xylene, etc. enclosed in the shell. It is a capsule which consists of an ionic liquid, and it is preferable that the temperature (expansion start temperature) which starts expansion | swelling is 100-155 degreeC, It is more preferable that it is 110-155 degreeC, It is further 130-155 degreeC preferable. By setting the temperature at which the expansion starts to 100 ° C. or higher, the thermal expansion microcapsule (D) hardly expands immediately after the resin is put into an extrusion molding machine when molding using a polyvinyl chloride resin. Therefore, stable molding can be made possible. Moreover, the temperature which starts expansion | swelling shall be 155 degrees C or less, and the temperature which this thermal expansion microcapsule (D) begins to expand | swell in a nozzle | cap | die becomes moderate in the molding temperature of the polyvinyl chloride type resin to be used.

  The thermal expansion microcapsule (D) used in the present invention preferably has a maximum expansion temperature (maximum expansion temperature) of 160 to 230 ° C, more preferably 160 to 220 ° C, and 160 to 210 ° C. More preferably. By setting the maximum expansion temperature to 160 ° C. or higher, appropriate expansion can be obtained at the timing before and after being discharged from the molding machine. Further, by setting the maximum expansion temperature to 230 ° C. or less, the temperature at which the thermal expansion microcapsule (D) expands to the maximum is appropriate at the molding temperature of the polyvinyl chloride resin to be used, and an efficient foaming state is obtained. be able to.

  Examples of the thermal expansion microcapsule (D) used in the present invention include “Matsumoto Microsphere” series manufactured by Matsumoto Yushi Seiyaku Co., Ltd., “EXPANCEL” series manufactured by Akzo Nobel, and “ADVANCEL” series manufactured by Sekisui Chemical Co., Ltd. .

<Metal hydroxide (E)>
The resin composition for a foamed resin sheet of the present invention preferably further contains a metal hydroxide (E). The metal hydroxide (E) functions as a flame retardant aid. Examples of the metal hydroxide (E) include magnesium hydroxide and aluminum hydroxide. By blending these, flame retardancy can be improved more efficiently. Moreover, magnesium hydroxide can make the external appearance at the time of shaping | molding better than the effect as a flame retardant adjuvant.

<Other ingredients>
(Ethylene copolymer polyvinyl chloride resin)
The resin composition for a foamed resin sheet of the present invention preferably further contains 1 to 30 parts by mass of an ethylene copolymer polyvinyl chloride resin obtained by copolymerizing ethylene which is an α-olefin with vinyl chloride. By containing an ethylene copolymer polyvinyl chloride resin, the affinity between the polyvinyl chloride resin (A) and the thermal expansion microcapsule (D) is improved, and the occurrence of plate-out during melt processing is suppressed. Thus, a foamed resin sheet having a particularly good appearance can be obtained.
The blending amount of the ethylene copolymer polyvinyl chloride resin is preferably 1 to 30 parts by mass. Moreover, as for the minimum of a compounding quantity, it is more preferable that it is 1.5 mass parts or more, and it is further more preferable that it is 2 mass parts or more. Moreover, as for the upper limit of a compounding quantity, it is more preferable that it is 20 mass parts or less, and it is further more preferable that it is 15 mass parts or less.

(Processing aid, heat stabilizer)
In addition, the resin composition for a foamed resin sheet of the present invention may further contain PMMA as a processing aid, an inhibitor for the eyes, and as a heat stabilizer, for example, a Ba-Zn heat stabilizer. You may go out.

  Polyvinyl chloride resin (A), plasticizer (B), zinc stannate (C), thermal expansion microcapsule (D), and metal hydroxide (E that can be preferably contained) used in the present invention ) Is not particularly limited, and can be mixed using a general stirrer.

<Content ratio of each component>
The blending amount of the plasticizer (B) with respect to 100 parts by mass of the polyvinyl chloride resin (A) is preferably 40 to 75 parts by mass. By making the compounding quantity of a plasticizer (B) 40 mass parts or more, surging at the time of manufacturing a foamed resin sheet can be prevented, and sheet | seat film formation becomes possible stably. On the other hand, by setting the blending amount of the plasticizer (B) to 75 parts by weight or less, the plasticizer from the foamed resin sheet can have sufficient moldability and workability without bleeding out. Moreover, more preferable flame retardancy can be imparted without causing a decrease in flame retardancy.

  The lower limit of the amount of the plasticizer (B) is preferably 45 parts by mass or more, and more preferably 50 parts by mass or more. Moreover, it is preferable that the upper limit of the compounding quantity of a plasticizer (E) is 70 mass parts or less, and it is more preferable that it is 65 mass parts or less.

  It is important that the compounding amount of zinc stannate (C) with respect to 100 parts by mass of the polyvinyl chloride resin (A) is 5 to 20 parts by mass. If the compounding quantity of zinc stannate (C) is 5 mass parts or more, the foamed resin sheet which is excellent in a flame retardance will be obtained. On the other hand, if the blending amount of zinc stannate (C) is 20 parts by mass or less, a foamed resin sheet having flame resistance sufficient for practical use can be obtained, and the film can be easily formed without excessively reducing the melt tension during processing. Is possible. The lower limit of the amount of zinc stannate (C) is preferably 7 parts by mass or more, and more preferably 8 parts by mass or more. Moreover, it is preferable that it is 18 mass parts or less, and, as for the upper limit of the compounding quantity of zinc stannate (C), it is more preferable that it is 15 mass parts or less.

It is important that the compounding amount of the thermal expansion microcapsule (D) with respect to 100 parts by mass of the polyvinyl chloride resin (A) is 1 to 20 parts by mass. By setting the blending amount of the thermal expansion microcapsule (D) to 1 part by mass or more, sufficient heat insulation can be imparted to the obtained foamed resin sheet, and the foamed resin sheet can be reduced in weight. Become. On the other hand, by setting the blending amount of the thermal expansion microcapsule (D) to 20 parts by mass or less, it is possible to suppress a decrease in mechanical strength, and to obtain a more preferable appearance.
The lower limit of the amount of the thermally expanded microcapsule (D) is preferably 2 parts by mass or more, and more preferably 2.5 parts by mass or more. Moreover, it is preferable that the upper limit of the compounding quantity of a thermal expansion microcapsule (D) is 17 mass parts or less, and it is more preferable that it is 15 mass parts or less.

  The compounding amount of the metal hydroxide (E) with respect to 100 parts by mass of the polyvinyl chloride resin (A) is preferably 5 to 15 parts by mass. A flame retardant effect can be improved by setting the compounding amount of the metal hydroxide (E) to 5 parts by mass or more, and a mechanical property does not deteriorate by setting the compounding amount to 15 parts by mass or less. It can be. Further, the lower limit of the amount of the metal hydroxide (E) is more preferably 6 parts by mass or more, and the upper limit is more preferably 12 parts by mass or less.

  The resin composition for a foamed resin sheet of the present invention includes a stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an antibacterial / antifungal agent, an antistatic agent, and a lubricant as long as the effects of the present invention are not impaired. Further, additives such as pigments and dyes can be contained.

[Foamed resin sheet]
The foamed resin sheet of the present invention is a foamed resin sheet obtained by thermoforming the above resin composition for a foamed resin sheet, wherein the thermal expansion microcapsules (thermally expanded by heat applied during the thermoforming) D).

  The foamed resin sheet is composed of a matrix and air bubbles. The matrix contains the above-described polyvinyl chloride resin (A), plasticizer (B), and zinc stannate (C). In some cases, the matrix further contains a metal hydroxide (E). Also good. The content ratio of each component is as described above.

  Bubbles are formed by thermally expanding the thermally expanded microcapsules when the resin composition for a foamed resin sheet is thermoformed. Since the shell constituting the thermal expansion microcapsule is not destroyed by thermal expansion, the shell exists between the bubbles and the matrix in an expanded state. Moreover, each bubble exists in the matrix in the mutually independent state. Further, in the bubbles of the present invention, volatile liquid may remain inside the shell after the sheet is cooled, and such a case is meant to be included as bubbles.

  The average particle diameter of the thermally expanded microcapsule (D) used in the resin composition for a foamed resin sheet is 5 to 50 μm, preferably 10 to 40 μm. This expands due to heat at the time of molding, and in the resulting foamed sheet In this case, bubbles are 60 to 200 μm, preferably 80 to 150 μm.

  The foamed resin sheet of the present invention preferably has a tensile elongation at break of 50% or more, more preferably 60% or more, still more preferably 80% or more, and particularly preferably 100% or more, based on JIS K7127. By using a tensile elongation at break of 50% or more, when used as a building material such as a flooring material or a wall material, for example, when a foamed resin sheet is attached to a plywood, the sheet can be prevented from breaking. .

  The foamed resin sheet of the present invention preferably has a tensile breaking strength measured based on JIS K7127 of 1.20 MPa or more, more preferably 1.40 MPa or more, and even more preferably 1.70 MPa or more. By using a tensile breaking strength of 1.20 MPa or more, when used as a building material such as a flooring material or a wall material, for example, when a foamed resin sheet is attached to a plywood, the sheet can be prevented from breaking. .

Further, the apparent density of the foamed resin sheet of the present invention is preferably 0.10~0.0.85g / cm ^3, more preferably 0.15~0.80g / cm ^3. By setting the density of the foamed resin sheet to 0.10 g / cm ³ or more, an excessive reduction in strength of the sheet can be suppressed. On the other hand, by setting the density of the foamed resin sheet to 0.85 g / cm ³ or less, it is possible to reduce the weight of the sheet. In the foamed resin sheet, the proportion of the air whose thermal conductivity is usually lower than that of the resin By increasing the value, the heat insulation can be improved. In addition, the said density is an apparent density measured based on JISK7222 (2005).

  In the foamed resin sheet of the present invention, the oxygen index measured based on JIS K7201 is preferably 23% or more, and more preferably 25% or more. By setting the oxygen index to 23% or more, the foamed resin sheet can be made sufficient as flame retardancy when used for, for example, building materials.

  In the foamed resin sheet of the present invention, the foamed state of the sheet is good, and the appearance of the sheet is good. By depositing a metal on the observation surface of the obtained sheet and observing the deposition surface by SEM, the appearance of the sheet can be observed, but the foamed resin sheet of the present invention has foam particles dispersed in the matrix, It can be observed that the sizes of the particles are uniform and the ratio of the expanded particles to the matrix resin is large.

[Method for producing foamed resin sheet]
Although the manufacturing method of the foamed resin sheet of this invention is not specifically limited, It can obtain by heat-molding the said resin composition for foamed resin sheets. The resin for the foamed resin sheet is blended with a stirrer and kneaded in a heated and melted state using a known kneader such as a Banbury mixer, single screw extruder, roll, kneader, etc. A composition is obtained. The melting temperature of the resin composition for the foamed resin sheet is appropriately determined according to the type of resin, the mixing ratio, the presence or absence of additives, and the type. The lower limit of the melting temperature is, for example, 150 ° C. or higher, preferably 170 ° C. The upper limit of the melting temperature is, for example, 220 ° C. or lower, preferably 200 ° C. or lower. By molding within such a melting temperature range, a foamed resin sheet having a good appearance can be molded without causing thermal deterioration of the polyvinyl chloride resin.

  A molten resin composition is obtained by melt-kneading the resin composition for a foamed resin sheet. Next, a foamed resin sheet can be obtained by molding the obtained molten resin composition for a foamed resin sheet into a sheet shape with a calender roll or a T-die molding machine.

  In extrusion molding, for example, a molten resin composition is extruded using a mold such as a T-die. In order to cool the extruded molten resin composition, for example, the molten resin composition is brought into contact with a cooled cooling machine such as a cast roll and rapidly cooled. Thereby, a molten resin composition is solidified and an unstretched sheet is obtained. The cooling temperature is not limited as long as it is lower than the melting temperature, but the upper limit of the cooling temperature is, for example, 90 ° C. or less, preferably 60 ° C. or less, and the lower limit of the cooling temperature is, for example, 0 ° C. or more, preferably Is 10 ° C. or higher.

  The unstretched sheet is a sheet that is not actively stretched for the purpose of increasing the strength of the sheet, but here, a sheet stretched to less than 2 times by a stretching roll during extrusion molding is also included in the unstretched sheet. .

Although the thickness of the foamed resin sheet of this invention is not specifically limited, It can set suitably with the use to be used. Generally, it is preferably 15 mm or less, more preferably 10 mm or less, further preferably 7 mm or less, further preferably 5 mm or less, and particularly preferably 2.5 mm or less. Further, it is preferably 0.5 mm or more, more preferably 1 mm or more, further preferably 1.5 mm or more, and particularly preferably 1.7 mm or more.
By setting the thickness of the foamed resin sheet within the above range, the workability of winding the sheet into a roll shape is improved, and efficient production becomes possible. Moreover, the flame retardancy and other physical property values can be made more preferable.
The foamed resin sheet of the present invention may be a single layer or a multilayer.

[Laminated sheet]
Another aspect of the present invention is a laminated sheet including at least one layer of the foamed resin sheet of the present invention, and more preferably a laminated sheet having the foamed resin sheet of the present invention as an intermediate layer.

  The foamed resin sheet of the present invention can be used as an intermediate layer, and a laminated sheet using a polyvinyl chloride resin (A) or other resins. For example, a polyvinyl chloride resin (A) layer can be provided on the surface layer and / or the back layer of the foamed resin sheet.

  For example, when the foamed resin sheet of the present invention is used for an application that requires excellent performance on the appearance of the surface of the sheet, by providing a polyvinyl chloride resin (A) layer on the surface layer, the appearance of the foamed resin sheet is improved. Problems can be suppressed.

  In this case, it is more preferable that the thermal expansion microcapsule (D) is not contained in the surface layer and / or the back surface layer of the laminated sheet. Note that “not containing thermally expanded microcapsules” includes containing a very small amount that does not impair the appearance due to the foaming action of thermally expanded microcapsules.

In addition, when a foamed resin sheet is used as an intermediate layer and a laminated sheet is formed using a polyvinyl chloride resin (A) or other resin, the plasticizer and flame retardant impart flame retardancy suitable for other resins. Can be included. Preferably, the intermediate layer and the front / back layer are made of the same resin, plasticizer, and flame retardant. However, the foamed resin sheet of the present invention is not limited to this, and for example, a phosphoric acid plasticizer as a plasticizer. It is also possible to use the most suitable flame retardant for other resins. By setting it as such a structure, a flame retardance can be improved more. When the flame retardant is blended in the front / back layer, the blending amount is preferably 20 to 55 parts by weight, more preferably 25 to 50 parts by weight with respect to 100 parts by weight of the base material such as the polyvinyl chloride resin (A). Parts, more preferably 30 to 45 parts by mass.
Since the surface layer and the back surface layer of the laminated sheet do not contain the thermal expansion microcapsule (D), even if the phosphorus-based plasticizer is included, poor appearance due to poor dispersibility of the thermal expansion microcapsule (D) occurs. There is nothing.

  In the foamed resin sheet of the present invention, a primer layer may be formed on one side and / or both sides as necessary.

  In the foamed resin sheet of the present invention, another resin layer can be provided according to weather resistance and other necessary purposes. This resin layer can be formed by laminating or coating a polyolefin resin, a polyester resin, an acrylic resin, a urethane resin, or the like. Further, this resin layer can be embossed.

As a method for producing a laminated sheet using the foamed resin sheet of the present invention, (1) a method in which a foamed resin sheet and other film layers are prepared in advance, and then the foamed resin sheet and other film layers are laminated, 2) A method of directly forming a foamed resin sheet and other film layers may be mentioned.
In the case of the method (1), an extrusion laminating method in which a foamed resin sheet and other film layers are extruded and laminated by a pressure roll can be used.
In the case of the method (2), the foamed resin sheet and other film layers can be prepared by an extrusion method such as a T-die extrusion method, a molding method such as an inflation method and a calendar method.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples. The numerical values in the following examples can be substituted for the numerical values (that is, the upper limit value or the lower limit value) described in the above embodiment.

[Materials used]
<Polyvinyl chloride resin (A)>
As the polyvinyl chloride resin (A), A-1 [Kaneka's trade name “S1001” (average polymerization degree 1000)], A-2 [Taiyo PVC's trade name “TH-2500” (average polymerization degree) 2,500)] was used.

<Plasticizer (B)>
As the phthalic acid-based plasticizer, B-1 [trade name “DOP” (dioctyl phthalate) of Jay Plus Co.] and B-2 [“DINP” (diisononyl phthalate)] were used.
As a phosphorus plasticizer, B-3 [Ajinomoto Fine Techno Co., Ltd. trade name “Leophos”] was used.
As the epoxy plasticizer, B-4 [trade name “M-6” of DIC Corporation] was used.

<Zinc stannate (C)>
As zinc stannate (C), C-1 [Nippon Tin Zinc Trioxide “Flamtard S” from Nippon Light Metal Co., Ltd.] was used.

<Thermal expansion microcapsule (D)>
As the thermal expansion microcapsule (D), D-1 [trade name “EXPANEL 930DU120” (expansion start temperature: 122 to 132 ° C.)] and D-2 [trade name “EXPANEL 951DU120” (expansion start temperature: Akzo Nobel) 132-142 ° C.)].

<Metal hydroxide (E)>
As the metal hydroxide (E), E-1 [magnesium hydroxide “KISUMA 5B” from Kyowa Chemical Co., Ltd.] and E-2 [aluminum hydroxide “BF 013”] were used.

<Ethylene Copolymer Polyvinyl Chloride Resin (Anti-eye inhibitor)>
Use F-1 [trade name “TE-1050” (average degree of polymerization 1,050, ethylene content 1.3 mass%) of Taiyo PVC Co., Ltd.] as an ethylene copolymer polyvinyl chloride resin (medium inhibitor). did.

<Flame Retardant>
Examples of the flame retardant include G-1 [antimony trioxide (AT-3) manufactured by Suzuhiro Chemical Co., Ltd.], G-2 [ammonium molybdate / aluminum hydroxide compound “SRK-803” manufactured by Kikuchi Color Co., Ltd.], G-3 [Calcium zinc molybdate compound “Keggard 911A” from JX Metal Trading Co., Ltd.], G-4 [Zinc borate “ALCANEX FRC-500” from Mizusawa Chemical Co., Ltd.] were used.

<Heat stabilizer>
As the heat stabilizer, two types of H-1 and H-2 [Ba-Zn heat stabilizers of Katsuta Chemical Industries, Ltd.] were used.

<Processing aids, eye-inhibiting agents>
As a processing aid, I-1 [PMMA “P530A” manufactured by Mitsubishi Chemical Corporation] was used. As an eye-opening inhibitor, J-1 ["P700" manufactured by Mitsubishi Chemical Corporation] was used.

[Evaluation method]
The foamed resin sheets of each Example and each Comparative Example were evaluated by the following methods. Here, the flow direction in which the foamed resin sheet is extruded from the T die is the vertical direction, and the orthogonal direction is the horizontal direction.

<Tensile breaking elongation and tensile breaking strength>
About the longitudinal direction of the obtained foamed resin sheet, a measurement part uses a dumbbell test piece having a width of 10 mm. Based on JIS K7127, measurement is performed at a temperature of 23 ° C., a gap between chucks of 40 mm, and a tensile speed of 300 mm / min. The tensile elongation at break (%) was calculated. If the tensile elongation at break is 50% or more and the tensile strength at break is 1.20 MPa or more, it can be said that the mechanical properties are excellent.
<Apparent density>
The apparent density was measured according to JIS K7222 (2005). If the density is 0.90 g / cm ³ or less, it can be said that the weight is excellent.

<Sheet appearance>
Metal was vapor-deposited on the observation surface of the obtained sheet, and the appearance of the sheet was evaluated by SEM observation of the vapor-deposited surface. The observation was performed using a scanning electron microscope (JSM-6390) manufactured by JEOL Ltd. at an acceleration voltage of 10 kV and an observation magnification of 30 times (minimum magnification).
Evaluation was performed based on the following criteria.
○: The foamed state is good and the particles are aligned.
Δ: intermediate between ○ and ×,
X: The foamed state is bad and the surface layer is rough,
If this evaluation is “◯” or “Δ”, it can be said that the sheet appearance is excellent.

<Flame retardance>
(Flammability test using oxygen index (JIS K7201))
The oxygen index of the obtained sheet (width 35 m, length 150 mm) was measured based on JIS K7201-2 (Procedure B—Propagation ignition method). Evaluation was performed according to the following criteria for three types of oxygen concentrations of 23%, 25%, and 27%.
○: It did not burn.
X: Burned.
-: Not measured.
If the oxygen index is 23% or more, it can be said that the flame retardancy is sufficient.

(Examples and Comparative Examples)
After blending the raw materials adjusted to the blending ratio shown in Table 1 using a Henschel mixer, the obtained mixture was put into a Φ40 mm single screw extruder equipped with a T die, and each resin temperature was 180 ° C. The foamed resin sheets according to Examples and Comparative Examples were obtained by extrusion molding so as to have a thickness.
About the obtained sheet | seat, it evaluated by the said evaluation method. The results are shown in Table 1.

[result]
As can be seen from Table 1, the foamed resin sheets according to Examples 1 to 6 have good mechanical strength because the breaking strength and breaking elongation are not less than the predetermined values. Moreover, since the apparent density is in a predetermined range, it has light weight. Moreover, since the oxygen index is not less than a predetermined value, it has flame retardancy. Furthermore, the appearance characteristics are good.
On the other hand, none of the sheets of Comparative Examples 1 to 6 contains zinc stannate. Since the sheets of Comparative Examples 1 and 2 contained a phosphorus-based plasticizer that is a flame retardant, they had flame retardancy, but had poor appearance. None of the sheets of Comparative Examples 3, 4, and 6 had flame retardancy. Although the sheet of Comparative Example 5 showed flame retardancy, the appearance was poor. The sheet of Comparative Example 7 did not show flame retardancy because it did not contain zinc stannate and the amount of plasticizer was too large. The sheets of Comparative Examples 8 and 9 do not contain thermally expandable microcapsules and zinc stannate. Therefore, the apparent density was large and the lightness was not provided. Further, the sheet of Comparative Example 9 did not exhibit flame retardancy because the amount of plasticizer was too large.

  FIG. 1 shows the appearance analysis results (SEM images) of the sheets of Examples 5 and 6 and Comparative Example 2. (A) is the SEM image of Example 5, (b) is the Example 6 and (c) is the SEM image of Comparative Example 2. In the sheets of Examples 5 and 6, it was observed that the expanded particles were dispersed in the matrix, the particle sizes were uniform, and the ratio of the expanded particles to the matrix resin was large.

  The foamed resin sheet of the present invention is excellent in heat insulating properties, light weight, mechanical properties, and flame retardancy, and is therefore used in applications that require light weight, heat insulation, sound insulation, vibration isolation, etc., for example, flooring materials, wall materials, doors for building materials. It can be used for window frames and the like, heat insulating materials for automobile members, and sound insulation materials.

Claims (13)

Plasticizer (B) 40-75 parts by mass, zinc stannate (C) 5-20 parts by mass, and thermally expandable microcapsules (D) 1-20 with respect to 100 parts by mass of the polyvinyl chloride resin (A). A resin composition for a foamed resin sheet comprising a mass part. The resin composition for foamed resin sheets according to claim 1, wherein the zinc stannate is zinc tin oxide. Furthermore, the resin composition for foamed resin sheets of Claim 1 or 2 which contains 5-15 mass parts of metal hydroxides (E) with respect to 100 mass parts of said polyvinyl chloride resin (A). The plasticizer (B) is at least one selected from the group consisting of phthalic acid plasticizers, trimellitic acid plasticizers, polyester plasticizers, and adipic acid plasticizers. The resin composition for foamed resin sheets in any one. It is a foaming resin sheet obtained by heat-molding the resin composition for foaming resin sheets of any one of Claims 1-4, Comprising: The said thermal expansion thermally expanded by the heat | fever applied in the case of the said thermoforming A foamed resin sheet having microcapsules (D). In a matrix containing 40 to 75 parts by mass of a plasticizer (B) and 5 to 20 parts by mass of zinc stannate (C) with respect to 100 parts by mass of a polyvinyl chloride resin (A), a thermal expansion micro A foamed resin sheet having closed cells resulting from the capsule (D) and having an apparent density of 0.1 to 0.85 g / cm ³ . The foamed resin sheet according to claim 6, wherein the closed cells resulting from the thermally expanded microcapsules (D) are thermally expanded microcapsules. The foamed resin sheet according to any one of claims 5 to 7, wherein the tensile elongation at break measured in accordance with JIS K7127 is 50% or more. The foamed resin sheet according to claim 5, wherein the oxygen index is 23% or more. The plasticizer (B) is at least one selected from the group consisting of phthalic acid plasticizers, trimellitic acid plasticizers, polyester plasticizers, and adipic acid plasticizers. The foamed resin sheet in any one. The laminated sheet containing at least 1 layer of the foamed resin sheet of any one of Claims 5-10. The laminated sheet according to claim 11, wherein the foamed resin sheet is provided in at least an intermediate layer. A step of thermoforming the resin composition for a foamed resin sheet according to any one of claims 1 to 4, wherein the thermal expansion microcapsules (D) are expanded by heat applied during the thermoforming. A method for producing a foamed resin sheet.