JP2008001885A - Thermoplastic resin foam and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thick thermoplastic resin foam which is excellent in heat resistance and chemical resistance, is also excellent in material recyclable environment suitability, and is suitable for building material uses, especially to provide the thermoplastic resin foam which satisfies such requirements for heat resistance and chemical resistance that can not be satisfied by a styrenic resin foam alone. <P>SOLUTION: This thermoplastic resin foam is characterized by foaming a thermoplastic resin composition containing a thermoplastic mixture comprising 0.1 to 50 wt.% of a copolymer (A) comprising aromatic vinyl units, unsaturated dicarboxylic anhydride units, and N-alkyl-substituted maleimide units, and 50 to 99.9 wt.% of a copolymer (B) comprising aromatic vinyl units and vinyl cyanide units, and having a foam thickness of 10 to 150 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin foam excellent in heat resistance, chemical resistance, surface property, moldability, and thermoplasticity used for a building heat insulating material, and a method for producing the same.

  Conventionally, styrene resin foams, cross-linked polyethylene foams, and rigid polyurethane foams have been widely used as heat insulating materials for buildings due to their suitability for construction and heat insulating properties.

  However, although the styrene resin foam is useful as a heat insulating material excellent in environmental compatibility in consideration of material recycling, since the heat resistant temperature of styrene as a base resin is around 80 ° C., a higher temperature range than that. In applications exposed to water (for example, panel curing materials for steam curing chambers, drying curing chambers, etc.), it has a problem that it cannot be used to cause deformation of the foam so that the shape cannot be maintained. .

  In addition, since the styrene resin foam has low chemical resistance, it is contained in the adhesive when, for example, a heat insulating material and a waterproof sheet such as a sheet waterproof bonding method in a roof heat insulating waterproof field are bonded with an adhesive. It was not resistant to the plasticizer contained in the solvent and the waterproof sheet, and the foam was dissolved and disintegrated and had a problem that it could not be used because the foam could be deformed so that the shape could not be retained. .

On the other hand, since the crosslinked polyethylene foam has high chemical resistance, it is preferably used as a heat insulating material for the sheet waterproof bonding method in the roof thermal insulation waterproof field, but the heat resistance is about the same as the styrene resin foam. Therefore, it has a problem that it cannot be used for applications exposed to a high temperature range of 80 ° C. or higher. In addition, since cross-linked polyethylene has a cross-linked structure, it is difficult to say that it is poor in material recyclability and excellent in environmental compatibility.
Further, it is generally known that the hard polyurethane foam has high chemical resistance like the above-mentioned crosslinked polyethylene foam, and further, since the hard polyurethane is a thermosetting resin, it has high heat resistance. However, the rigid polyurethane foam has a problem that it cannot be used for, for example, a heat-insulating panel of a steam curing room, because it has a high hygroscopic property and the heat resistance is extremely deteriorated in the moisture-absorbing state. It was. In addition, since hard polyurethane is a thermosetting resin, it is difficult to say that it is poor in material recyclability and excellent in environmental compatibility.

  Each of the three types of foams has advantages and disadvantages, and it is difficult to have both characteristics.

  On the other hand, some examples of the heat resistance improvement of the styrene resin foam excellent in environmental compatibility like material recyclability and having improved heat resistance are disclosed.

  For example, efforts have been made on a heat-resistant styrene resin extruded foam plate obtained by extrusion foaming a styrene-α-methylstyrene-acrylonitrile copolymer (see Patent Document 1). In this approach, by using a styrene-α-methylstyrene-acrylonitrile copolymer, the heat distortion temperature becomes 92 ° C. or higher and 110 ° C. or lower, and heat resistance is improved as compared with conventional styrene resin foams. Is recognized. However, since the main component is made of styrene, there is a limit to chemical resistance, and when a sheet waterproof adhesive is applied in the roof thermal insulation waterproof field, the foam dissolves and collapses due to the influence of the solvent contained in the adhesive. However, it cannot be used to cause deformation of the foam such that the shape cannot be maintained.

  In addition, efforts have been made to improve heat resistance by incorporating a maleimide compound into a styrene resin or bonding at a molecular level (see Patent Documents 2 to 4). In the field of injection molding, heat resistance has been improved by introducing a maleimide compound into a styrene resin, and it has been used mainly in the automotive field as a heat resistance improver for ABS resins.

  However, a resin composition in which a maleimide compound is introduced into a styrene resin has improved heat resistance, but tends to decrease fluidity and elongation in a molten state. When the foam is obtained from the resin composition, the flowability and elongation of the molten resin composition containing the foaming agent are reduced. Even if it is going to form the foam attached using a type | mold, a cell film is hard to expand | extend and the tendency for the surface property at the time of shaping | molding to deteriorate becomes large. Furthermore, if the molding die is cooled too much as in the method for producing a styrene resin foam, the temperature difference between the surface layer of the cooled foam and the inner layer at which cell flow occurs is increased. For this reason, the foam has a problem that a crack occurs from the inside toward the surface, and the foam cannot be formed into a plate shape.

  These techniques have not yet achieved a foam having the advantages of a styrene resin foam, a crosslinked polyethylene foam, and a rigid polyurethane foam.

Therefore, development of a thermoplastic resin foam that is excellent in heat resistance and chemical resistance, retains surface properties, moldability, and bending properties, and is excellent in environmental compatibility capable of material recycling is awaited.
JP-A-60-199624 JP-A-61-78846 Japanese Patent Laid-Open No. 2-184418 Japanese Patent Laid-Open No. 4-25532

  An object of the present invention is to provide a thermoplastic resin foam that is excellent in heat resistance and chemical resistance, retains surface properties, moldability, and bending properties, and also has excellent environmental compatibility that allows material recycling. is there.

  As a result of diligent research in view of the prior art, the present inventors have found that a copolymer imparted with heat resistance and chemical resistance from the viewpoint of heat resistance and chemical resistance, and chemical resistance and fluidity. From the viewpoint, the present inventors have found that a foam obtained by foaming a thermoplastic resin composition containing a copolymer imparted with chemical resistance and fluidity satisfies the above object, and has completed the present invention.

  That is, the present invention relates to [1] a copolymer (A) comprising an aromatic vinyl unit, an unsaturated dicarboxylic anhydride unit and an N-alkyl-substituted maleimide unit, and a copolymer comprising an aromatic vinyl unit and a vinyl cyanide unit. A thermoplastic resin foam obtained by foaming a thermoplastic resin composition containing a thermoplastic resin mixture comprising a coalescence (B), the thermoplastic resin mixture comprising 0.1% by weight of the copolymer (A) The thermoplastic resin foam comprising the above-mentioned less than 50% by weight and the copolymer (B) more than 50% by weight and 99.9% by weight or less, wherein the foam has a thickness of 10 to 150 mm. .

  Furthermore, the present invention relates to [2] the thermoplastic resin foam according to [1], wherein the aromatic vinyl unit is a styrene unit.

  Furthermore, the present invention relates to the thermoplastic resin foam according to any one of [1] to [2], wherein the [3] unsaturated dicarboxylic anhydride unit is a maleic anhydride unit.

  Furthermore, the present invention relates to the thermoplastic resin foam according to any one of [1] to [3], wherein the [4] N-alkyl-substituted maleimide unit is an N-phenylmaleimide unit.

  Furthermore, the present invention relates to [5] the thermoplastic resin foam according to any one of [1] to [4], wherein the vinyl cyanide unit is acrylonitrile.

  Furthermore, the present invention relates to [6] 100 parts by weight of a thermoplastic resin mixture comprising a copolymer (A) and a copolymer (B) as a foaming agent in foaming, a) a group consisting of ether and alkyl chloride At least one selected from the group consisting of 0.5 to 10 parts by weight, and b) 0 to 6 parts by weight of hydrocarbon, according to any one of the above [1] to [5] The present invention relates to a thermoplastic resin foam.

  Furthermore, the present invention relates to the thermoplastic resin foam according to [6] above, wherein [7] ether is dimethyl ether.

  Furthermore, the present invention provides [8] The alkyl chloride according to any one of [6] to [7], wherein the alkyl chloride is at least one selected from the group consisting of methyl chloride and ethyl chloride. The present invention relates to a thermoplastic resin foam.

  Furthermore, the present invention provides [9] above, wherein the hydrocarbon is at least one kind of saturated hydrocarbon selected from saturated hydrocarbons having a boiling point in the range of −50 ° C. to 85 ° C. To the thermoplastic resin foam according to any one of to [8].

  Further, the present invention provides [10] at least one hydrocarbon selected from the group consisting of propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane, n-hexane and cyclohexane. The thermoplastic resin foam according to any one of the above [6] to [9], which is a saturated hydrocarbon of

Furthermore, the present invention relates to the thermoplastic resin foam according to any one of the above [1] to [10], wherein [11] the foam density is 20 to 100 kg / m ³ .

  Furthermore, the present invention provides the thermoplastic resin according to any one of [1] to [11] above, wherein the average diameter of the bubbles forming the [12] foam is 0.05 to 2.0 mm. The present invention relates to a resin foam.

  Further, the present invention provides [13] a copolymer (A) comprising an aromatic vinyl unit, an unsaturated dicarboxylic anhydride unit and an N-alkyl-substituted maleimide unit, in an amount of 0.1% by weight to less than 50% by weight, and an aromatic Copolymer (B) composed of vinyl units and vinyl cyanide units (B) A thermoplastic resin composition containing a thermoplastic resin mixture composed of more than 50% by weight and 99.9% by weight or less is heated and melted, and a foaming agent is added and foamed. Forming a possible gel-like substance, cooling the gel-like substance, extruding the gel-like substance to a lower pressure region through a die, and using a molding die placed in close contact with or in contact with the die A method for producing a thermoplastic resin foam including a step of forming a foam, wherein a resin temperature of the gel substance at an outlet of the cooling step is relative to a glass transition temperature of the thermoplastic resin mixture. Characterized in that 0 to 70 ° C. is high temperature, a method for producing a thermoplastic resin foam.

  Furthermore, the present invention relates to the method for producing a thermoplastic resin foam according to [13], wherein the [14] die temperature is 5 to 50 ° C. lower than the resin temperature.

  Furthermore, the present invention relates to the method for producing a thermoplastic resin foam according to the above [13] or [14], wherein [15] the foam is gradually cooled in a molding die.

  According to the present invention, there is provided a thermoplastic resin foam suitable for building materials, which has excellent heat resistance and chemical resistance, retains surface properties, moldability and bending properties, and is excellent in environmental compatibility capable of material recycling. Obtainable.

  In particular, it is possible to obtain a thermoplastic resin foam that satisfies the required qualities of heat resistance and chemical resistance that cannot be satisfied by a styrene resin foam alone, and that further retains moldability and bending characteristics.

  More specifically, in an oven at 100 ° C or 120 ° C atmosphere, the volume change rate of the foam after exposure for 24 hours is 3% or less for a long time, and sheet waterproof adhesion in the field of rooftop insulation and waterproofing. Even when using adhesives applied to the construction method and plasticizers contained in waterproof sheets, the surface properties, moldability, and bending characteristics were maintained without causing shape deformation such as dissolution and dissolution of the foam. A thermoplastic resin foam can be obtained.

  Hereinafter, the present invention will be described in detail.

  The copolymer (A) used in the present invention comprises an aromatic vinyl unit, an unsaturated dicarboxylic anhydride unit, and an N-alkyl-substituted maleimide unit. Examples of the aromatic vinyl unit include styrene, α-methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, chlorostyrene, vinyltoluene, and vinylxylene. Of these, styrene and α-methylstyrene are preferred from the viewpoint of compatibility with the copolymer (B) and ease of polymerization, and styrene, which is inexpensive in price, is most preferred. Examples of the unsaturated dicarboxylic acid anhydride unit include maleic anhydride, itaconic anhydride, and citraconic anhydride. From the viewpoint of compatibility with the copolymer (B), ease of polymerization, and low cost, maleic anhydride. Acid is preferred. Furthermore, as N-alkyl substituted maleimide units, N-methylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-4-diphenylmaleimide, N-2-chlorophenylmaleimide, N-4-bromo Examples thereof include phenylmaleimide and N-1-naphthylmaleimide, and N-phenylmaleimide is optimal from the viewpoint of compatibility with the copolymer (B), ease of polymerization, and low cost.

  When the total amount of the aromatic vinyl unit, unsaturated dicarboxylic acid anhydride unit and N-alkyl substituted maleimide unit is 100% by weight, the N-alkyl substituted maleimide unit is 40% by weight or more in view of heat resistance. In consideration of water absorption resistance and moisture absorption, the unsaturated dicarboxylic acid anhydride unit is preferably 5% by weight or less.

  The copolymer (B) used in the present invention comprises an aromatic vinyl unit and a vinyl cyanide unit. As the aromatic vinyl unit, as described above, styrene and α-methylstyrene are preferable from the viewpoint of compatibility with the copolymer (A) and ease of polymerization, and styrene which is inexpensive in price. Is the best. Examples of the vinyl cyanide unit include acrylonitrile, methacrylonitrile, and α-chloroacrylonitrile, and acrylonitrile is preferred from the viewpoint of compatibility with the copolymer (A) and ease of polymerization. In view of compatibility with the copolymer (A), ease of polymerization, and low cost, a copolymer of styrene and acrylonitrile is preferable.

  The thermoplastic resin composition in the present invention is a thermoplastic resin composition containing a thermoplastic resin mixture comprising the copolymer (A) and the copolymer (B). The thermoplastic resin composition in the present invention is one in which the resin mixture is contained in an amount of 70% or more with respect to the entire thermoplastic resin composition.

  The thermoplastic resin composition in the present invention is a resin composition comprising the copolymer (A) and the copolymer (B). The weight ratio of the copolymer (A) and the copolymer (B) in the thermoplastic resin composition is 100 ° C. heat resistance or both 120 ° C. heat resistance and chemical resistance, and in addition, surface properties and moldability. Further, from the viewpoint of maintaining the bending property, it is preferable that the copolymer (A) is 0.1% by weight or more and less than 50% by weight, and the copolymer (B) is more than 50% by weight and 99.9% or less, More preferably, the copolymer (A) is 10 wt% or more and less than 50 wt%, the copolymer (B) is more than 50 wt% and 90 wt% or less, and the copolymer (A) is 20 wt% or more and 50 wt% or less. More preferably, it is less than 50% by weight and the copolymer (B) is more than 50% by weight and 80% by weight or less.

  As a foaming agent for obtaining the thermoplastic resin foam of the present invention, a foaming agent containing no chlorine atom is used for the thermoplastic resin mixture comprising the copolymer (A) and the copolymer (B). Can do. Moreover, as such a foaming agent, 1 type chosen from the group which consists of a physical type foaming agent and a chemical type foaming agent can be used, or 2 or more types can be mixed and used. By not containing a chlorine atom, it is preferable because the burden on the environment is reduced. However, in order to achieve the object of the present invention, it is not always necessary to contain no chlorine atom.

  Specific examples of the physical foaming agent include hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane, hexane, and cyclohexane; 1,1-difluoroethane, 1 , 2-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, , 1,1,2,2-pentafluoroethane, difluoromethane, trifluoromethane and other fluorinated hydrocarbons; carbon dioxide, nitrogen, water, argon, helium and other inorganic gases; dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl Ether, n-butyl ether, diisoamyl ether, furan, furfural, 2-methyl Ethers such as furan, tetrahydrofuran and tetrahydropyran; alkyl chlorides such as methyl chloride, ethyl chloride, propyl chloride and isopropyl chloride; methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, propionic acid Carboxylic acid esters such as methyl ester and propionic acid ethyl ester; alcohols such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol and t-butyl alcohol, dimethyl ketone, methyl ethyl ketone and diethyl ketone Methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl Piruketon, ketones such as ethyl -n- butyl ketone, and the like. These can be used alone or in admixture of two or more.

  Specific examples of the chemical foaming agent include, for example, N, N′-dinitrosopentamethylenetetramine, p, p′-oxybis-benzenesulfonylhydrazide, hydrazodicarbonamide, sodium carbonate, azodicarbonamide, terephthalazide, 5 -Phenyltetrazole, p-toluenesulfonyl semicarbazide and the like. These can be used alone or in admixture of two or more.

  Among the above-mentioned blowing agents, from the viewpoint of protecting the ozone layer, hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane, hexane, cyclohexane, carbon dioxide, Inorganic gases such as nitrogen, water, argon, helium, ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl Alcohols such as alcohol, i-butyl alcohol and t-butyl alcohol are preferred.

  Of the foaming agents described above, the foaming agent is mainly selected from the group consisting of (a) ethers and alkyl chlorides in consideration of weight reduction of the foam and stability of extrusion foaming. In addition, one containing 0.5 to 10 parts by weight of one or more and (b) 0 to 6 parts by weight of hydrocarbon is preferable.

  Examples of the ether in the foaming agent used in the present invention include the ethers described above. Of these, dimethyl ether reduces the extrusion pressure during extrusion foaming, and stably produces an extruded foam. This is preferable. The amount of ether used is preferably 0.5 to 10 parts by weight, more preferably 1.5 to 6 parts by weight, and more preferably 3 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin mixture. Is particularly preferred. When the amount of ether used is in the range of 0.5 to 10 parts by weight, the foamability and gas dispersibility in the foam are good, and the foamability is good.

  Examples of the alkyl chloride in the foaming agent used in the present invention include the alkyl chlorides described above. Among these, methyl chloride and ethyl chloride are reduced in extrusion pressure during extrusion foaming, and are stably extruded and foamed. It is preferable at the point by which a body is manufactured. The amount of alkyl chloride used is preferably 0.5 to 10 parts by weight, more preferably 1.5 to 6 parts by weight, and more preferably 3 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin mixture. Part is particularly preferred. When the amount of alkyl chloride used is in the range of 0.5 to 10 parts by weight, the foamability and gas dispersibility in the foam are good, and the foamability is good.

  Examples of the hydrocarbon in the foaming agent of the present invention include the hydrocarbons described above, but if the boiling point is too low, the vapor pressure becomes high, and a high pressure is required for handling, which tends to be a problem in production. If the boiling point is too high, the foaming agent remains as a liquid in the foam bubbles and tends to lower the heat resistant temperature of the foam. Therefore, a saturated hydrocarbon having a boiling point in the range of −50 ° C. to 85 ° C. is preferable. Examples of the saturated hydrocarbon having a boiling point in the range of −50 ° C. to 85 ° C. include propane, cyclopropane, n-butane, i-butane, cyclobutane, n-pentane, i-pentane, neopentane, cyclopentane, hexane, Examples include 2-methylpentane, 3-methylpentane, 1,2-dimethylbutane, cyclohexane and the like. Of these, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane, n-hexane and cyclohexane are preferred from the viewpoint of production stability. The amount of hydrocarbon used is preferably 0 to 6 parts by weight and more preferably 2 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic resin mixture. If the usage-amount of hydrocarbon exists in the range of 0-6 weight part, the gas dispersibility to a foam is good and foamability is good.

In the present invention, additives such as a nucleating agent, a stabilizer, a lubricant, a flame retardant, an antistatic agent, a plasticizer, a water absorbing agent, and a radiation inhibitor are blended in the resin composition as necessary. Also good. (
Since the thermoplastic resin foam of the present invention is characterized by being a plate-like foam, the thickness of the thermoplastic resin foam of the present invention is preferably 10 to 150 mm, more preferably 20 to 100 mm. . For example, in the case of a heat insulating material used for applications such as building materials, in order to give preferable heat insulating properties, it tends to be difficult to obtain with a sheet-like foam having a thickness of less than 10 mm. Moreover, when the thickness of the foam exceeds 150 mm, the closed cell ratio tends to decrease, and as a result, the heat insulating properties, dimensional stability, strength, and the like may decrease.

Density of the thermoplastic resin foam in the present invention is preferably in the range of 20 and 100 kg / ^{m 3,} and more preferably in the range of 25~50kg / ^{m 3.} If the density is in the range of 20 to 100 kg / m ³ , it is preferable from the viewpoint of expression of surface compressive strength represented by plane compressive strength.
Examples of the cell structure forming the thermoplastic resin foam of the present invention include a uniform cell structure and a composite cell structure in which large and small cells are mixed, but the cell structure is not particularly limited.

  The average diameter of the bubbles in the thermoplastic resin foam of the present invention is preferably preferably from 0.05 to 2.0 mm, more preferably from 0.1 to 1.0 mm. The bubble diameter is measured, for example, according to ASTM D-3576 from a photograph obtained by sampling a part of the cross-section of the extruded foam and magnifying it with a scanning electron microscope. be able to. All of the bubble diameters are not necessarily in the above range, and at least the average value of the bubble diameters is in the above range. When the average diameter of the bubbles is less than 0.05 mm, the moldability is greatly lowered, and stable production tends to be difficult. Moreover, when an average diameter exceeds 2.0 mm, there exists a tendency for the external appearance of the product surface to deteriorate.

  The thermoplastic resin foam of the present invention can be obtained by a known method using the resin composition. For example, the thermoplastic resin mixture is supplied to a known heat-melting and kneading apparatus such as an extruder and melted by heating, and a step of adding a foaming agent under a high-pressure condition, a step of forming a foamable gel substance Then, the step of cooling the gel-like substance, the step of extruding and foaming the gel-like substance to the low-pressure region through a die such as a slit die from the high-pressure region, and using a molding die placed in close contact with or in contact with the die A thick plate-like thermoplastic resin foam can be obtained through the step of forming the foam to be molded.

  Prior to adding the blowing agent, the resin composition is heated to its glass transition temperature or melting point or higher. The foaming agent may be added by a method that can disperse in the heat-melted resin. That is, the melted resin composition can be mixed, press-fitted or compounded by means known in the field related to the production and / or development of foams, for example, an extruder, a mixer and the like. Moreover, each foaming agent component can be put into an extruder individually or simultaneously. Furthermore, each foam component may be blended in either a liquid or gas state.

  As a procedure for adding various additives such as a flame retardant to the thermoplastic resin mixture, for example, (1) after adding and mixing various additives such as a flame retardant to the thermoplastic resin mixture, A procedure for supplying to a melt-kneading apparatus and heating and melting, and further adding and mixing a foaming agent. (2) After supplying a thermoplastic resin mixture to a melt-kneading apparatus such as an extruder and heating and melting, a flame retardant, etc. Procedures of adding and mixing various additives, and further adding and mixing a foaming agent, (3) obtained by previously adding various additives such as flame retardant to the thermoplastic resin mixture and melt-kneading The resin composition is again supplied to an extruder and melted by heating, and then a procedure for adding and mixing a foaming agent is included, but the timing of adding various additives to the thermoplastic resin mixture is particularly limited. Not.

  In the production of the thermoplastic resin foam of the present invention, the heating temperature, melt kneading time, and melt kneading means when the thermoplastic resin mixture, foaming agent, and various additives added as necessary are heated and melt kneaded. There is no particular limitation on the above.

  The heating temperature may be equal to or higher than the temperature at which the thermoplastic resin mixture melts (glass transition temperature or melting point), but is preferably a temperature at which decomposition and deterioration of the resin due to the influence of a flame retardant and the like are suppressed as much as possible.

  The melt-kneading time varies depending on the amount of extrusion per unit time, the type of melt-kneading equipment, etc., so it cannot be determined unconditionally, but the thermoplastic resin mixture and the foaming agent or additive are uniformly dispersed and mixed. The time required is set as appropriate.

  Examples of the melt-kneading means include a screw type extruder such as a single screw or a twin screw, but there is no particular limitation as long as it is used for normal extrusion foaming. However, when the dispersibility of the foam is required, the extruder is preferably a twin screw type. In order to suppress degradation and degradation of the resin as much as possible, the screw shape of the extruder is preferably a low shear type.

  As the extrusion conditions in the present invention, it is preferable to maintain the internal pressure of the extrusion system at a high pressure so that the foaming agent does not vaporize in the extruder or the mold and is sufficiently dissolved in the resin.

  As one means thereof, the pressure in the slit die (hereinafter sometimes referred to as “slit pressure”) is preferably 3 MPa or more, and more preferably 4 MPa or more. It is preferable that the pressure in the slit die be 3 MPa or more because phenomena such as gas blowing, void generation in the foam, pressure fluctuation in the extruder system, and accompanying foam cross-sectional profile fluctuation are less likely to occur.

  The resin temperature of the gel substance at the exit of the step of cooling the gel substance is preferably 20 to 70 ° C. higher than the glass transition temperature of the thermoplastic resin mixture, More preferably, the temperature is higher by 30 to 60 ° C. By setting the resin temperature at the process outlet to cool the gel-like substance to a temperature suitable for foaming within the above range, the gel substance is introduced into the die in a state where there is almost no increase in the slit pressure of the die and temperature unevenness. And good extrusion moldability and surface properties can be obtained.

  The set temperature of the die is preferably controlled to a temperature 5 to 50 ° C. lower than the resin temperature, and more preferably 10 to 40 ° C. lower. By setting the die set temperature within the above range, it is possible to maintain the die slit pressure and obtain a foam having good surface properties.

  The foam molding method is not particularly limited, and can be obtained, for example, by releasing pressure from the high pressure region to the low pressure region through a die such as a slit die having a slit shape used for extrusion molding. The extrusion foaming method of forming a thermoplastic resin extruded foam using a molding die installed in close contact with or in contact with the slit die and a molding roll installed adjacent to the downstream side of the molding die. For example, it is possible to obtain a plate-like foam that is thick and has a large cross-sectional area.

  The shape of the slit die includes a rectangular shape, a coat hanger shape, a fishtail shape, a tee shape, etc. When a wide plate-like foam is to be obtained, a coat hanger shape or a tee shape slit die is used. Is preferred.

  Furthermore, when trying to obtain a plate-like foam having a thickness of 10 to 150 mm, from the viewpoint of suppressing the dimensional enlargement ratio in the thickness direction and the dimensional enlargement ratio in the width direction of the molding die shape relative to the slit die exit shape. A method of forming a desired foam width by using a slit die whose slit die outlet is enlarged in a flat plate shape is advantageous. In particular, the thermoplastic resin mixture comprising the copolymer (A) and the copolymer (B) in the present invention tends to be brittle with respect to the polystyrene-based resin, so that the expansion rate in the width direction is suppressed as much as possible. It is preferred to select a method.

  In addition, when the resin composition is used, since the elongation of a resin such as a polystyrene resin cannot be expected from its resin characteristics, the surface of the extruded foam and molding are required to ensure the surface properties of the obtained extruded foam. It is important to reduce the resistance to the mold.

  Means for reducing the resistance between the extruded foam and the molding die include, for example, (1) heating the molding die by using steam, oil, an electric heater, etc., (2) polytetrafluoroethylene resin, etc. It is conceivable to install a material having a low surface resistance such as a sheet made of a fluororesin at the interface between the extruded foam surface and the molding die.

  Furthermore, it is important to gradually cool the foam obtained by extrusion foaming from the slit die in order to ensure the surface properties and physical properties of the obtained thermoplastic resin foam. That is, even when the surface of the foam is cooled and solidified, in the state where the inside of the foam is still fluid and has a foaming force, the surface portion cannot withstand the foaming force inside, The surface of the foam may cause defects such as cracks. In addition, as described above, the closed cell ratio of the obtained foam tends to decrease, and as a result, the heat insulating properties, dimensional stability, strength, and the like may decrease. Slow cooling conditions are also affected by the resin temperature at the time of foaming and may be adjusted as appropriate.However, depending on the length of the molding die, the heating temperature for the molding die, the installation distance of the material with low surface resistance, etc. Can be adjusted.

  The thermoplastic resin foam of the present invention is superior in heat resistance and chemical resistance as compared with conventional styrene-based extruded foams, and can maintain surface properties, moldability and bending characteristics. It is suitably used for heat insulating materials or panel heat insulating materials such as a steam curing room and a drying curing room that are exposed to a higher temperature range than ordinary building materials.

  Hereinafter, a thermoplastic resin foam having both heat resistance and chemical resistance of the present invention and having surface properties, moldability, and bending properties will be described in detail by way of specific examples. It is not limited to only. Unless otherwise specified, “part” represents “part by weight” and “%” represents “% by weight”.

  About the characteristic of the foam obtained in Examples 1-10 shown below, Comparative Examples 1-2, and Reference Examples 1-6, a foam density, an average cell diameter, 100 degreeC heat resistance, 120 degreeC heat resistance, glass The transition temperature, adhesive resistance, plasticizer resistance, bending deflection and surface properties were measured according to the following methods.

(1) Extrudability
The extrusion moldability was evaluated by visual inspection for the occurrence of gas ejection from the die and the occurrence of fluctuations in the slit pressure under the conditions described in Examples, Comparative Examples or Reference Examples. Judgment criteria are as follows. Somewhat good is a pass level.
Good: Gas ejection from the die per hour and occurrence of fluctuations in slit pressure are less than once.
Slightly good: The gas ejection from the die per hour and the occurrence of fluctuation of the slit pressure are 1 to 2 times.
Defective: The gas ejection from the die per hour and the occurrence of fluctuations in the slit pressure are 3 times or more.

(2) Foam density (kg / m ³ )
The foam density was determined based on the following formula, and the unit was shown in terms of kg / m ³ .
Foam density (g / cm ³ ) = foam weight (g) / foam volume (cm ³ )

(3) Average cell diameter (mm)
The cell diameter in each of the extrusion direction, the width direction, and the thickness direction of the obtained foam was measured according to ASTM D-3576.
That is, the cross-section in the width direction of the foam is magnified and projected 50 to 100 times, and the cell diameter (HD) in the thickness direction and the cell diameter (TD) in the width direction are measured. Next, the cross section in the extrusion direction was enlarged and projected, and the cell diameter (MD) in the extrusion direction was measured.
The average cell diameter was calculated from the following formula by taking the cube of the product of the cell diameters in each direction.
Average cell diameter = (HD x TD x MD) ^1/3

(4) 100 ° C. heat resistance, 120 ° C. heat resistance (volume change rate of foam)
After creating the foam, after conditioning for 10 days in a constant temperature room at 23 ° C. and 55% humidity, a test piece having a thickness of 25 mm × width of 100 mm × length of 100 mm was cut out to 100 ° C. ± 2 ° C. Were heated in a hot air dryer set at 120 ° C. ± 2 ° C. for 24 hours, the volume change rate (%) before and after heating was calculated, and the presence or absence of heat resistance was judged according to the following criteria.
A: Volume change rate of the foam is 1% or less.
A: The volume change rate of the foam is more than 1% and 3% or less.
(Triangle | delta): Volume change rate of a foam exceeds 3% and is 5% or less.
X: Volume change rate of the foam exceeds 5%.

(5) Glass transition temperature The glass transition temperature of the thermoplastic resin mixture and the obtained foam was determined by using a differential differential calorimeter (manufactured by Shimadzu Corporation: DSC-60A) at a heating rate of 10 ° C / min. After raising the temperature to 300 ° C. and holding for 10 minutes, the temperature was lowered to 30 ° C. at a temperature lowering rate of 10 ° C./min. , Measured according to the method for determining the glass transition temperature of JIS K7121. In addition, about the foam, after making a foam, it measured after adjusting the state for 10 days in a constant temperature room of 23 degreeC and 55% of humidity.

(6) Adhesive resistance After the foam was prepared, the condition was adjusted for 10 days in a constant temperature room at 23 ° C. and 55% humidity, and then a test piece having a thickness of 25 mm × width of 100 mm × length of 300 mm was cut out and specified for waterproof adhesion to rubber sheets After applying 0.4 kg / m ^{2 of} agent (manufactured by Mitsuboshi Belting Co., Ltd .: “Neobond RW” (solvent: toluene / 50-60%, gasoline / 10-20%, xylene / 10%)), the state of the foam surface Was observed.
○: Dissolution / disintegration of foam surface, no irregularities.
Δ: Some irregularities on the surface of the foam.
X: Dissolution / disintegration of the foam surface.

(7) Plasticizer resistance After the foam was prepared, after conditioning for 10 days in a constant temperature room at 23 ° C. and 55% humidity, a test piece having a thickness of 25 mm × width of 100 mm × length of 300 mm was cut out to obtain a length of 50 mm. It was immersed in DOP (200 ml) as a plasticizer for 24 hours, and the foam shape after taking out was observed.
○: Dissolution / disintegration of foam and no unevenness.
X: Dissolution / disintegration of foam or unevenness.

(8) Bending Deflection After preparing the foam and adjusting the condition for 10 days in a constant temperature room at 23 ° C. and 55% humidity, a test piece having a thickness of 25 mm × width of 75 mm × length of 300 mm was cut out and in accordance with JIS K7221. A bending test was performed, and the amount of bending deflection when the foam broke was measured.

(9) Surface properties
The surface property of the obtained foam was visually evaluated. Judgment criteria are as follows.
Good: A foam having a beautiful skin layer having 3 or less cracks, cracks, dents and voids (pores) per 1 m in the extrusion flow direction of the foam surface.
Defect: Foam surface is a foam capable of forming only a poor skin layer having more than 3 cracks, cracks, dents and voids (pores) per 1 m in the extrusion direction of the foam surface.

(Example 1)
As a copolymer (A), manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: DENKA IP (265 ° C. × 10 kg melt flow rate (hereinafter referred to as MFR) = 0.2 g / min), copolymer (B) As Toyo Styrene Co., Ltd., trade name: Toyo AS (220 ° C. × 10 kg MFR = 1.8 g / min) is used, and the copolymer (A) / copolymer (B) is 10% / Mixing at a ratio of 90%. To 100 parts of these resin mixtures, 0.3 parts of talc (trade name: Talcan powder, manufactured by Hayashi Kasei Co., Ltd.) as a nucleating agent was dry blended, and the resulting resin composition was one-stage with a diameter of 65 mm. This was fed at a rate of 50 kg / hour to a two-stage connection type extruder in which a first-stage extruder and a second-stage extruder having a diameter of 90 mm were connected in series. 4. The resin composition supplied to the first stage extruder is melted and kneaded by heating to about 230 ° C., and then dimethyl ether as a foaming agent in the vicinity of the tip of the first stage extruder (side connected to the second extruder). 0 part was pressed into the molten thermoplastic resin composition. Thereafter, in the second stage extruder connected to the first stage extruder, the mixture is cooled so that the resin temperature at the outlet of the second stage extruder (cooling process outlet) becomes 145 ° C. while being kneaded and cooled. A thermoplastic resin composition was extruded into the atmosphere from a die lip of a rectangular slit die provided at the tip of the machine, and a molding die (surface material: surface-treated with polytetrafluoroethylene resin) through which oil at 100 ° C. was passed. An extruded foam plate having a cross-sectional shape having a thickness of about 30 mm and a width of about 100 mm was obtained using iron, height 25 mm × width 120 mm, and a forming roll. The temperature of the die lip was set to 130 ° C., and the gap was a rectangular cross section having a thickness direction of 2 mm and a width direction of 50 mm.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 2)
Change the mixing ratio of copolymer (A) / copolymer (B) to 20% / 80% and cool so that the resin temperature at the outlet of the second stage extruder (cooling process outlet) is 150 ° C. An extruded foam was obtained under the same conditions as in Example 1 except that the die lip temperature was set to 135 ° C and the mold temperature was set to 110 ° C.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 3)
Change the mixing ratio of copolymer (A) / copolymer (B) to 30% / 70%, and cool so that the resin temperature at the second stage extruder outlet (cooling process outlet) is 155 ° C. An extruded foam was obtained under the same conditions as in Example 1 except that the die lip temperature was set to 140 ° C and the mold temperature was set to 120 ° C.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

Example 4
The mixing ratio of copolymer (A) / copolymer (B) was changed to 40% / 60%, the heating temperature in the first stage extruder was about 240 ° C., and the outlet of the second stage extruder (cooling process outlet). Extruded foam was obtained under the same conditions as in Example 1 except that the resin temperature was set to 160 ° C, the die lip temperature was set to 145 ° C, and the mold temperature was set to 130 ° C.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 5)
Change the mixing ratio of copolymer (A) / copolymer (B) to 47% / 53%, and cool so that the resin temperature at the second stage extruder outlet (cooling process outlet) is 165 ° C. An extruded foam was obtained under the same conditions as in Example 4 except that the die lip temperature was set to 150 ° C. and the mold temperature was set to 140 ° C.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 6)
Extruded foam was obtained under the same conditions as in Example 3 except that 4.0 parts of dimethyl ether and 0.1 parts of talc were used.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 7)
Extruded foam was obtained under the same conditions as in Example 6 except that the blowing agent was changed to 3.0 parts of dimethyl ether and 3.0 parts of isobutane.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 8)
Extruded foam was obtained under the same conditions as in Example 6 except that the blowing agent was changed to 3.0 parts of methyl chloride and 3.0 parts of isobutane.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

Example 9
Extruded foams were obtained under the same conditions as in Example 6 except that the blowing agent was changed to 3.0 parts of dimethyl ether and 3.0 parts of normal butane.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Example 10)
The same conditions as in Example 6 except that 3.0 parts of dimethyl ether, 3.0 parts of isobutane and 1.0 part of water were added, and 1.0 part of bentonite and 0.5 parts of silicon dioxide were added as the water absorbing agent. An extruded foam was obtained.
The properties of the obtained foam are shown in Table 1. As compared with Comparative Examples 1 and 2 below, a foam having excellent heat resistance and chemical resistance and having surface properties, moldability and bending properties was obtained.

(Comparative Example 1)
As a base resin, PS resin (manufactured by PS Japan Co., Ltd., trade name: G9401, 200 ° C. × 5 kg, MFR = 0.2 g / min) is used, and nucleating agent is used for 100 parts of PS resin. As a dry blend of 0.3 parts of talc, the obtained resin composition was fed into a two-stage connected extruder in which a 65 mm diameter first stage extruder and a 90 mm diameter second stage extruder were connected in series at 50 kg / hour. Was supplied at a rate of 4. The resin composition supplied to the first stage extruder is melted and kneaded by heating to about 220 ° C., and then dimethyl ether as a foaming agent near the tip of the first stage extruder (side connected to the second extruder). 0 part was pressed into the molten thermoplastic resin composition. Then, in the second stage extruder connected to the first stage extruder, the resin temperature at the outlet of the second stage extruder (cooling process outlet) is cooled to 125 ° C. while kneading and cooling, and the second stage extrusion A thermoplastic resin composition was extruded into the atmosphere from a die lip of a rectangular slit die provided at the tip of the machine, and a molding die (surface material: surface-treated with polytetrafluoroethylene resin) through which oil at 30 ° C. was passed. An extruded foam plate having a cross-sectional shape having a thickness of about 30 mm and a width of about 100 mm was obtained using iron, height 25 mm × width 120 mm, and a forming roll. The temperature of the die lip was set to 115 ° C., and the gap was a rectangular section with a thickness direction of 2 mm and a width direction of 50 mm.
The properties of the obtained foam are shown in Table 1. Only the foam which is inferior to heat resistance and chemical resistance compared with the following Examples 1-10 was obtained.

(Comparative Example 2)
Change the mixing ratio of copolymer (A) / copolymer (B) to 0% / 100% and cool so that the resin temperature at the second stage extruder outlet (cooling process outlet) becomes 130 ° C. An extruded foam was obtained under the same conditions as in Example 1 except that the die lip temperature was set to 120 ° C.
The properties of the obtained foam are shown in Table 1. Only the foam which is inferior to heat resistance and chemical resistance compared with the following Examples 1-10 was obtained.

(Reference Example 1)
Except that the heating temperature in the first stage extruder is about 260 ° C, the resin temperature at the outlet of the second stage extruder (cooling process outlet) is 200 ° C, and the die lip temperature is set to 180 ° C. An extruded foam was obtained under the same conditions as in Example 3. However, since the resin temperature is high, the slit pressure is reduced by gas ejection and foaming in the die, the extrusion moldability is deteriorated, and only a rough shape / surface can be obtained, and a satisfactory foam cannot be obtained. It was.

(Reference Example 2)
Extruded foam was obtained under the same conditions as in Example 3, except that 30 ° C. oil was passed through the molding die. However, since the molding die temperature is low, the cracks on the surface due to the occurrence of blistering from the inside of the foam become large, and only a poor shape / surface can be obtained, and a satisfactory foam cannot be obtained. .

(Reference Example 3)
Except that the heating temperature in the first stage extruder is about 260 ° C, the resin temperature at the outlet of the second stage extruder (cooling process outlet) is 200 ° C, and the die lip temperature is set to 180 ° C. An extruded foam was obtained under the same conditions as in Example 7. However, since the resin temperature is high, the slit pressure is reduced by gas ejection and foaming in the die, the extrusion moldability is deteriorated, and only a rough shape / surface can be obtained, and a satisfactory foam cannot be obtained. It was.

(Reference Example 4)
Extruded foam was obtained under the same conditions as in Example 7 except that 30 ° C. oil was passed through the molding die. However, since the molding die temperature is low, the cracks on the surface due to the occurrence of blistering from the inside of the foam become large, and only a poor shape / surface can be obtained, and a satisfactory foam cannot be obtained. .

(Reference Example 5)
The mixing ratio of copolymer (A) / copolymer (B) was changed to 60% / 40%, the heating temperature in the first stage extruder was about 250 ° C., and the outlet of the second stage extruder (cooling process outlet). The extruded foam was obtained under the same conditions as in Example 1 except that the resin temperature was set to 190 ° C., the die lip temperature was set to 170 ° C., and the mold temperature was set to 170 ° C.
The properties of the obtained foam are shown in Table 1. Compared with the following Examples 1-10, the bending deflection amount fell and the foam inferior to a bending characteristic was obtained.

(Reference Example 6)
The mixing ratio of copolymer (A) / copolymer (B) was changed to 80% / 20%, the heating temperature in the first stage extruder was about 270 ° C., and the outlet of the second stage extruder (cooling process outlet). Extruded foam was obtained under the same conditions as in Example 1 except that the resin temperature was set to 200 ° C., the die lip temperature was set to 190 ° C., and the mold temperature was set to 190 ° C.
The properties of the obtained foam are shown in Table 1. Compared with the following Examples 1-10, the bending deflection amount fell and the foam inferior to a bending characteristic was obtained.

Claims (15)

  Thermoplastics comprising a copolymer (A) comprising an aromatic vinyl unit, an unsaturated dicarboxylic anhydride unit and an N-alkyl substituted maleimide unit, and a copolymer (B) comprising an aromatic vinyl unit and a vinyl cyanide unit. A thermoplastic resin foam obtained by foaming a thermoplastic resin composition containing a resin mixture, wherein the thermoplastic resin mixture is 0.1% by weight or more and less than 50% by weight of the copolymer (A). (B) A thermoplastic resin foam comprising more than 50% by weight and 99.9% by weight or less, wherein the foam has a thickness of 10 to 150 mm.   The thermoplastic resin foam according to claim 1, wherein the aromatic vinyl unit is a styrene unit.   The thermoplastic resin foam according to claim 1 or 2, wherein the unsaturated dicarboxylic anhydride unit is a maleic anhydride unit.   The thermoplastic resin foam according to any one of claims 1 to 3, wherein the N-alkyl-substituted maleimide unit is an N-phenylmaleimide unit.   The thermoplastic resin foam according to any one of claims 1 to 4, wherein the vinyl cyanide unit is acrylonitrile.   As a foaming agent in foaming, at least one selected from the group consisting of (a) ether and alkyl chloride is added to 100 parts by weight of the thermoplastic resin mixture composed of the copolymer (A) and the copolymer (B). The thermoplastic resin foam according to any one of claims 1 to 5, wherein 0.5 to 10 parts by weight and (b) 0 to 6 parts by weight of hydrocarbon are used.   The thermoplastic resin foam according to claim 6, wherein the ether is dimethyl ether.   The thermoplastic resin foam according to claim 6 or 7, wherein the alkyl chloride is at least one selected from the group consisting of methyl chloride and ethyl chloride.   The thermoplastic resin according to any one of claims 6 to 8, wherein the hydrocarbon is at least one saturated hydrocarbon selected from saturated hydrocarbons having a boiling point in the range of -50 ° C to 85 ° C. Resin foam.   The hydrocarbon is at least one or more saturated hydrocarbons selected from the group consisting of propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopentane, n-hexane and cyclohexane; The thermoplastic resin foam according to claim 9, characterized in that The thermoplastic resin foam according to any one of claims 1 to 10, wherein the foam density is 20 to 100 kg / m ³ .   The thermoplastic resin foam according to any one of claims 1 to 11, wherein an average diameter of bubbles forming the foam is 0.05 to 2.0 mm.   Copolymer comprising aromatic vinyl unit, unsaturated dicarboxylic anhydride unit and N-alkyl-substituted maleimide unit (A) 0.1% by weight or more and less than 50% by weight, and comprising aromatic vinyl unit and vinyl cyanide unit A step of heating and melting a thermoplastic resin composition containing a thermoplastic resin mixture composed of more than 50% by weight and not more than 99.9% by weight of copolymer (B), and a step of cooling the gel-like substance Manufacturing a thermoplastic resin foam, including a step of extruding the gel-like substance through a die into a lower pressure region, and forming a foam by forming using a molding die placed in close contact with or in contact with the die The method of the present invention is characterized in that the resin temperature of the gel substance at the outlet of the cooling step is 20 to 70 ° C higher than the glass transition temperature of the thermoplastic resin mixture. Method for manufacturing a sexual resin foam.   14. The method for producing a thermoplastic resin foam according to claim 13, wherein the die temperature is 5 to 50 ° C. lower than the resin temperature.   The method for producing a thermoplastic resin foam according to claim 13 or 14, wherein the foam is gradually cooled in a molding die.