JP2006062274A - Manufacturing method of styrenic resin foam by extrusion foaming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a styrenic resin foam by extrusion foaming, the foam which is light and can meet the use wherein dimensional stability under high temperature atmosphere is required. <P>SOLUTION: The manufacturing method of the styrenic resin foam by extrusion foaming is the one wherein the styrenic resin foam having a density of 25-45 kg/m<SP>3</SP>and a thickness of 10-150 mm is formed by heating/melting a styrenic resin, adding a foaming agent and subjecting the mixture to extrusion foaming. The method is characterized in that: (A) a styrenic base material resin containing a styrene homopolymer/a methacrylic acid-modified polystyrene in a weight ratio of 75/25-0/100 is heated and molten and the molten composition of the styrenic resin further added with the foaming agent is subjected to extrusion foaming, and thereafter (B) the mold temperature (T°C) of the extrusion molding is controlled, in relation with HDT (t°C) under 1.82 MPa load of the styrenic base material resin, so as to satisfy the general formula: (t-10)≤T≤(t+25). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plate-like styrene resin extruded foam used for a heat insulating material for buildings and the like and a method for producing the same. More specifically, the present invention relates to a styrene resin extruded foam having excellent environmental compatibility, high heat insulation performance, strength suitable for building material use, and flame retardancy, and a method for producing the same. In particular, the present invention relates to a styrene resin extruded foam that requires more heat resistance than normal use conditions.

  Conventionally, styrene resin extruded foam has been widely used as a heat insulating material for buildings because of its workability and suitability for heat insulation. Here, among use as a heat insulating material of a building, for example, in an application where heat resistance is required rather than general use conditions such as a roof heat insulating application, a styrenic resin extruded foam usually used may have a dimensional change or There were cases where the deformation was large and difficult to use.

Then, patent document 1 is mention | raise | lifted as an example of examination which improves the heat resistance of a styrene resin extrusion foam. The publication includes at least one component of acrylic acid, methacrylic acid, and maleic anhydride, and relates to a foam plate having a density of 60 to 200 kg / m ³ and a wall thickness of 2.5 to 7 mm. Although the technical contents for specifying the relationship between the bubble film and the bending deflection coefficient of the foamed plate are disclosed, it relates to a low foamed foam, specifically a sheet-like product. Because of the thin thickness, the molded product itself is not easily subjected to large strain selectively on the surface portion, and it is difficult to cause large temperature unevenness due to the thickness during cooling in sheet molding or heating of the sheet product.

  On the other hand, in the case of a highly foamed plate-shaped molded body, the mold is cooled in a state where it is subjected to a large pressure during extrusion foam molding. Due to the uneven temperature, the molded product tends to be distorted when the molded product is allowed to cool.

  Usually, the use limit temperature of the plate-like styrene resin extruded foam used as a heat insulating building material is about 80 ° C. If it can improve the heat resistance of about 10 ° C and improve the dimensional stability of the foam in a high temperature atmosphere of about 90 ° C, it can be applied to applications that require higher heat resistance than general use conditions, such as rooftop insulation. It becomes possible and the scope of application is greatly expanded.

It has been desired to develop a styrene resin extruded foam that maintains its shape in such an environment.
JP-A-57-72830

  The present invention aims to solve the above-mentioned problems, and relates to a foam having excellent high temperature dimensional stability.

  The inventors of the present invention have made extensive studies, studied the modification of the styrene resin that is the base resin, and worked on maintaining the shape performance of the styrene resin foam at a high temperature. The inventors have found that specific molding conditions are effective and have arrived at the present invention.

That is, the present invention
(1) A styrene resin foam obtained by heating and melting a styrene resin, adding a foaming agent, and extrusion-foaming the styrene resin, and (A) styrene homopolymer / methacrylic acid modified polystyrene = 75 by weight ratio. After the styrene-based resin containing 25/0/100 is melted by heating and the styrene-based resin melt composition mixed with a foaming agent is extruded and foamed, (B) the extrusion mold temperature (T ° C.) is changed to styrene. Foam density 25 characterized by controlling the general base material (t−10) ≦ T ≦ (t + 25) in relation to HDT (t ° C.) at 1.82 MPa load of the base resin. A method for producing an extruded foam of styrene resin having a foam thickness of 10 to 150 mm at ˜45 kg / m ³ .
(2) The method for producing a styrene resin extruded foam according to claim 1, wherein the volume change rate when the foam is heated at 90 ° C. for 24 hours is −10% to + 10%.
(3) The method for producing a styrene resin extruded foam according to claim 1 or 2, wherein the methacrylic acid modified polystyrene has a methacrylic acid modification rate of 3% to 10%.
(4) MFR of methacrylic acid modified polystyrene is 1-5 g / 10min, The manufacturing method of the styrene resin extrusion foam in any one of Claims 1-3 characterized by the above-mentioned.
(5) The method for producing a styrene resin extruded foam according to any one of claims 1 to 4, wherein the foaming agent contains a saturated hydrocarbon having 3 to 5 carbon atoms and an ether.
(6) The method for producing a styrene resin extruded foam according to claim 5, wherein the foaming agent contains another non-halogen foaming agent.
(7) The bubbles forming the foam are mainly composed of bubbles having a bubble diameter of 0.25 mm or less and bubbles having a bubble diameter of 0.3 to 1 mm, and these bubbles are dispersed in the form of sea islands through the cell membrane. The method for producing a styrene resin extruded foam according to any one of claims 1 to 6, wherein bubbles having a diameter of 0.25 mm or less have an occupied area ratio of 10 to 90% per cross-sectional area of the foam.
(8) The method of producing a styrene resin extruded foam according to any one of claims 1 to 7, wherein the foam has a thermal conductivity of 0.034 W / mK or less.
It is about.

  According to the present invention, it is possible to obtain a styrene resin extruded foam excellent in shape retention performance at high temperatures.

  The present invention relates to a method for producing a styrene resin extruded foam in which the volume change rate when a foam is heated at 90 ° C. for 24 hours is in the range of −10% to + 10%.

  As an element for that, by finding that the heat resistance performance of the styrenic base resin and the mold temperature conditions at the time of molding are important, by producing a styrene resin extruded foam with these combinations as control factors, The inventors have found that the dimensional accuracy is dramatically improved and have completed the present invention. That is, the present invention is to obtain a styrene resin extruded foam having an excellent high temperature volume change rate by effectively combining two elements for maintaining the volume change rate.

  The styrenic base resin used in the present invention shows a value of 85 ° C. or higher in heat resistance evaluation at a deflection temperature under load of 1.82 MPa (hereinafter abbreviated as HDT), and has a melt flow rate ( 200 ° C., 5 kg load) is 1 to 5 g / 10 min. This is because if the heat resistance evaluation of HDT is 85 ° C. or higher, the volume change rate when heated for 24 hours at 90 ° C. atmospheric temperature as a foam is easily maintained.

  The flow characteristics of the styrenic base resin of the present invention are required to have a melt flow rate (200 ° C., 5 kg load) of 1 to 5 g / 10 min, preferably 1 to 4 g / 10 min.

  By being in this range, there is no significant difference in the fluidity between the polystyrene resin to be mixed and the extrusion system, so that stable extrusion foaming is possible and a phenomenon such as uneven foaming hardly occurs. As such a styrene base resin, it is required that the mixing ratio (% by weight) of the methacrylic acid-modified polystyrene resin and the polystyrene resin is 25/75 to 100/0. The methacrylic acid-modified polystyrene used in the present invention is polystyrene that has been modified with methacrylic acid, and the method for modifying methacrylic acid is not particularly limited. The methacrylic acid modification rate (% by weight) in the methacrylic acid modified polystyrene is preferably 3 to 10%, and more preferably 5 to 8%. A modification rate in this range is preferable from the viewpoints of both the effect of improving heat resistance and the polymerization stability.

  When the styrenic base resin is in such a range of resin ratio and methacrylic acid conversion rate, when it is made into a foam, the heat resistance deformation of the base resin when heated in a 90 ° C. atmosphere for 24 hours Can be secured.

  The styrene resin used in combination with the methacrylic acid modified polystyrene used in the present invention is preferably a styrene homopolymer from the viewpoint of processability.

  The control condition (T ° C.) of the extrusion mold temperature at the time of molding of the present invention is (t−10) ≦ T ≦ with respect to HDT (t ° C.) at 1.82 MPa load of the styrene base resin. By satisfying the relationship of (t + 25), it is easy to maintain the volume change rate when heated at 90 ° C. ambient temperature for 24 hours. The condition (t-5) ≦ T ≦ (t + 20) is preferable.

  When the relationship between T and t satisfies (t−10) ≦ T ≦ (t + 25), stress due to contact friction with the mold is reduced during cooling by the extrusion mold, which is the final stage of the extrusion process. The molded body can pass through the cooling section with a degree of freedom that can be relaxed, and the surface strain of the obtained styrene resin extruded foam can be reduced. By reducing the surface strain of the styrene resin extruded foam as described above, the shape change due to strain relaxation can be suppressed even by heating for 24 hours at an ambient temperature of 90 ° C.

  Furthermore, in order to more preferably perform the strain relaxation, it is preferable to adjust the resin temperature at the time of passing through the slit die of the styrene resin melt composition mixed with the foaming agent to 110 ° C. to 130 ° C. and perform extrusion foaming.

  The composition used as the raw material for the styrene resin extruded foam of the present invention comprises a styrene base resin and a foaming agent as essential components, preferably using a flame retardant, a processing aid and a stabilizer, and if necessary. It consists of water-absorbing substances and other additives.

  Although there is no restriction | limiting in particular as a foaming agent used for this invention, It is preferable to use a non-halogen type foaming agent from viewpoints, such as ozone layer destruction in recent years, an environmental impact, etc., and it is 1 of C3-C5 saturated hydrocarbon. Species or two or more and one or more ethers selected from the group consisting of dimethyl ether, diethyl ether, and methyl ethyl ether, and other blowing agents as required (except for halogen-based blowing agents) It is particularly preferred to use it.

  Examples of the saturated hydrocarbon having 3 to 5 carbon atoms used in the present invention include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like.

  In the case of saturated hydrocarbons having 3 to 5 carbon atoms, n-butane, i-butane, and a mixture of n-butane and i-butane are preferred, and i-butane is particularly preferred from the viewpoint of foamability and thermal insulation performance of the foam. .

  Examples of the ethers used in the present invention include dimethyl ether, diethyl ether, methyl ethyl ether, and the like, and dimethyl ether is preferred from the viewpoint of foamability, foam moldability, and stability.

  Other non-halogen foaming agents used in the present invention are not particularly limited. For example, inorganic foaming agents such as water and carbon dioxide, alcohols such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol and t-butyl alcohol, dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n Ketones such as propyl ketone, methyl n-butyl ketone, methyl i-butyl ketone, methyl n-amyl ketone, methyl n-hexyl ketone, ethyl n-propyl ketone, ethyl n-butyl ketone, methyl formate, ethyl formate, propyl formate Chemical foaming agents such as esters, carboxylic acid esters such as formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester and propionic acid ethyl ester, and azo compounds can be used. These other non-halogen foaming agents can be used alone or in admixture of two or more.

  Among other non-halogen-based foaming agents, water and carbon dioxide are more preferable from the viewpoints of foamability, safety, foam formability, and the like, and water is particularly preferable.

  By using other non-halogen-based foaming agents, good plasticizing effect and foaming aid effect can be obtained, the extrusion pressure can be reduced, and the foam can be stably produced.

  In particular, when water is used as a foaming agent, in the foam, bubbles with a relatively small bubble diameter (hereinafter referred to as small bubbles) having a bubble diameter of approximately 0.25 mm or less, and a bubble diameter of approximately 0.3 mm to 1 mm. A foam having a characteristic cell structure in which bubbles having a relatively large bubble diameter (hereinafter referred to as large bubbles) are mixed in a sea-island shape is obtained, and the foam characteristics, moldability, and productivity of the resulting foam are obtained. And the heat insulation performance is improved.

  In the production of the styrene resin foam of the present invention, the amount of the foaming agent to be added or injected into the styrene resin is appropriately changed according to the setting value of the expansion ratio, etc. The total amount is preferably 3 to 10 parts by weight with respect to 100 parts by weight of the styrene resin. More preferably, it is 4.5 to 8 parts by weight. If the amount of the foaming agent added is in the range of 3 to 10 parts by weight, the foaming ratio will be moderate, light weight and heat insulation will be exhibited as a resin foam, and defects such as voids will occur in the foam. It is preferable because it is difficult.

  From the viewpoint of obtaining a foam having a good quality such as stable foam production and appearance, in the foaming agent to be added, one or more kinds of saturated hydrocarbons having 3 to 5 carbon atoms are added in styrene resin 100. It is preferable to set it as 2-5 weight part with respect to a weight part. More preferably, it is 3 to 5 parts by weight. The addition amount of one or more ethers selected from the group consisting of dimethyl ether, diethyl ether, and methyl ethyl ether is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the styrenic resin. More preferably, it is 1.5 to 4 parts by weight.

  Further, when water is used as the other foaming agent, the amount is set to 0.3 to 3 parts by weight with respect to 100 parts by weight of the styrenic resin in terms of processability and the generation of the small bubbles and large bubbles. preferable. Preferably it is 0.5-2 weight part.

  The pressure when adding or injecting the foaming agent is not particularly limited as long as it is higher than the internal pressure of an extruder or the like.

In the styrene resin foam in the present invention, it is preferable to use a flame retardant in order to meet the demand in the application. As the flame retardant, it is more preferable to use at least one selected from halogen-based flame retardants.
Further, a phosphate ester compound and a nitrogen-containing compound may coexist. Examples of the halogen-based flame retardant used in the present invention include, as brominated flame retardants, hexabromocyclododecane, tetrabromocyclooctane, dibromoneopentyl glycol, tribromoneopentyl alcohol, tris (tribromoneopentyl) phosphate. , Bromides of aliphatic or alicyclic hydrocarbons such as tris (2,3-dibromopropyl) isocyanurate, tetrabromoethane, hexabromobenzene, ethylenebispentabromodiphenyl, decabromodiphenylethane, decabromodiphenyl ether, octa Brominated aromatic compounds such as bromodiphenyl ether and 2,3-dibromopropylpentabromophenyl ether, tetrabromobisphenol A, tetrabromobisphenol A bis (2,3-dibromo Propyl ether), tetrabromobisphenol A (2-bromoethyl ether), tetrabromobisphenol A diglycidyl ether, tetrabromobisphenol A bis (allyl ether), adducts of tetrabromobisphenol A diglycidyl ether and tribromophenol, etc. Brominated bisphenols and their derivatives, tetrabromobisphenol A polycarbonate oligomers, brominated bisphenol derivatives oligomers such as tetrabromobisphenol A diglycidyl ether and brominated bisphenol adduct epoxy oligomers, ethylene bistetrabromophthalimide, bis ( 2,4,6-tribromophenoxy) ethane brominated aromatic compounds, brominated acrylic resins, ethylenebisdibromonor Such Luna Nji dicarboximide and the like. Examples of the chlorinated flame retardant include chlorinated aliphatic compounds such as chlorinated paraffin, chlorinated naphthalene, and perchloropentadecane, chlorinated aromatic compounds, and chlorinated alicyclic compounds. Among these, brominated flame retardants are preferable from the viewpoint of flame retardancy, and hexabromocyclododecane, tetrabromocyclooctane, tris (2,3-dibromopropyl) isocyanurate, dibromo are particularly preferable from the viewpoint of compatibility with styrene resins. Neopentyl glycol and tetrabromobisphenol A bis (2,3-dibromopropyl ether) are preferred, and the amount to be added is 0.1 to 6.0 parts by weight. When the content of the halogen-based flame retardant is within this range, a foam that exhibits desired flame retardancy and good heat resistance can be obtained.

  Specific examples of phosphoric acid ester compounds include trialkyl phosphates such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate (preferably those having 1 to 12 carbon atoms as the alkyl group), tri Trialkoxyalkyl phosphates such as butoxyethyl phosphate (alkoxyalkyl groups preferably have 2 to 12 carbon atoms), dialkyl phosphates (alkyl groups preferably have 1 to 12 carbon atoms), monoisodecyl phosphate, etc. Fats such as monoalkyl phosphates (alkyl groups having 1 to 12 carbon atoms are preferred), 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, etc. Phosphates, triphenyl phosphate, tricresyl phosphate, trixyl phosphate, tris (isopropylphenyl) phosphate, tris (phenylphenyl) phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylyl diphenyl phosphate, di (isopropyl Triaryl phosphates such as phenyl) phenyl phosphate (the rule group may be substituted with an alkyl group, a phenyl group, etc.), diphenyl (2-ethylhexyl) phosphate, diphenyl (2-acryloyloxyethyl) phosphate, diphenyl (2- Methacryloyloxyethyl) phosphates such as diarylalkyl phosphates (aryl groups, alkyl groups may be substituted) Such group based phosphate esters.

  The content of the phosphoric ester compound is preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the styrene resin in terms of obtaining a flame retardant synergistic effect with the halogen flame retardant and / or the nitrogen-containing compound. .

  Specific examples of the nitrogen-containing compound include monoalkyl cyanurates such as cyanuric acid and methyl cyanurate, dialkyl cyanurates such as diethyl cyanurate, trialkyl cyanurates such as trimethyl cyanurate and triethyl cyanurate, phenyl cyanurate, and diphenyl. Dialkyl phenyl cyanurates such as cyanurate, triphenyl cyanurate, dimethylphenyl cyanurate, monoalkyl isocyanurates such as isocyanuric acid and methyl isocyanurate, dialkyl isocyanurates such as diethyl isocyanurate, trimethyl isocyanurate, triethyl isocyanurate, etc. Trialkyl isocyanurate, phenyl isocyanurate, diphenyl isocyanurate, triphenyl isocyanurate, Dialkylphenyl isocyanurates such as methylphenyl isocyanurate, mono (aminoalkyl) isocyanurates such as mono (2-aminoethyl) isocyanurate, di (aminoalkyl) isocyanurates such as di (2-aminoethyl) isocyanurate, tri Tri (aminoalkyl) isocyanurate such as (2-aminoethyl) isocyanurate, tri (hydroxymethyl) isocyanurate, tri (2-hydroxyethyl) isocyanurate, tri (2-hydroxypropyl) isocyanurate Bis (carboxyl) such as di (hydroxyalkyl) isocyanurate such as alkyl) isocyanurate, di (hydroxymethyl) isocyanurate, and bis (2-carboxyethyl) isocyanurate Kill) isocyanurate, 1,3,5-tris (2-carboxyethyl) isocyanurate and the like 1,3,5-tris (carboxyalkyl) isocyanurate, tris (2,3-epoxypropyl) isocyanurate and the like It is done.

  The content of the nitrogen-containing compound is preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the styrene-based resin in terms of obtaining a flame retardant synergistic effect with the halogen-based flame retardant and / or the phosphate ester compound. .

  As processing aids used in the present invention, inorganic compounds such as silica, talc, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate, sodium stearate, stearic acid Compounds such as magnesium, barium stearate, liquid paraffin, olefin wax, stearylamide compound are used.

As the stabilizer used in the present invention, light-resistant stabilizers such as phenolic antioxidants, phosphorus stabilizers, benzotriazoles and hindered amines are used.
Further, if necessary, a water-absorbing substance is used particularly when water is used as another foaming agent.

  Examples of the water-absorbing substance used in the present invention include smectites such as saponite, hectorite, montmorillonite and bentonite, water-absorbing or water-swelling clays such as swellable fluorine mica, and organically treated products thereof, zeolite, water-absorbing material. 1 type (s) or 2 or more types, such as an anhydrous silica which has silanol groups, such as a functional polymer and Nippon Aerosil Co., Ltd. AEROSIL, can be added. Thus, the action of generating the small bubbles and large bubbles in the foam can be further improved, and the moldability, productivity and heat insulation performance of the resulting foam are further improved.

  The water-absorbing substance used here is considered to absorb water that is not compatible with the styrenic resin to form a gel, which can be uniformly dispersed in the styrenic resin in the gel state. used.

  The content of the water-absorbing substance used in the present invention is appropriately adjusted depending on the amount of water added and the like, but is preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the styrenic resin. Preferably it is 0.3-8 weight part, Most preferably, it is 0.5-7 weight part. If the content of the water-absorbing substance is in the range of 0.2 to 10 parts by weight, the water-absorbing substance causes moderate water adsorption, which causes preferable water dispersion in the extruder and causes bubble irregularities. Since the preferable water-absorbing substance dispersion in the extruder can be obtained, the heat insulating performance of the foam and the low variation performance of the foam can be secured.

  Among the water-absorbing substances, smectite is preferable. The smectite is preferably a clay mineral containing montmorillonite as a main component, such as montmorillonite or bentonite. Bentonite as used in the present invention is a basic clay mineral whose main component is montmorillonite and contains accompanying minerals such as quartz, α-cristobalite, opal, feldspar, mica and the like. Speaking of chemical components, bentonite is mainly composed of silicon oxide, and the second most chemical component is aluminum oxide. Montmorillonite is composed of a thin silicate layer of about 1 nm, the surface of the plate-like crystal particles is negatively charged, and an exchangeable cation such as sodium or calcium is interposed between the layers to charge it. It is said to be a clay mineral that maintains its neutrality and hydrates water molecules with exchangeable cations between layers when water comes in contact with them, and the layers swell.

  As the smectite used in the present invention, bentonite is particularly preferable. Typical examples of bentonite include natural bentonite and purified bentonite. Also, organic bentonite can be used. The smectite in the present invention includes montmorillonite-modified products such as anionic polymer-modified montmorillonite, silane-treated montmorillonite, and highly polar organic solvent composite montmorillonite.

  Bentonite can be obtained as, for example, Bentonite Hotaka, Wenger from Toyshun Mining Co., Ltd. Such bentonites can be used alone or in admixture of two or more.

  The content of smectite such as bentonite is appropriately adjusted depending on the amount of water added and the like, but is preferably 0.2 to 10 parts by weight, more preferably 0.8 parts per 100 parts by weight of the styrenic resin. 3 to 8 parts by weight, particularly preferably 0.5 to 7 parts by weight, most preferably 1 to 5 parts by weight. When the smectite content is in the range of 0.2 to 10 parts by weight, moderate water adsorption occurs due to smectite with respect to the amount of water injected, and a good molded article is obtained due to good dispersion of water in the extruder. In addition, since uniform dispersion of the inorganic powder present in the styrene resin can be obtained in the styrene resin, it is possible to secure a foam holding closed cells that suppresses unevenness of the bubbles and has good heat insulation performance. The body is obtained. The mixing ratio of water / smectite (bentonite) is in a weight ratio, preferably 0.02 to 20, more preferably 0.1 to 10, particularly preferably 0.15 to 5, most preferably 0.25 to 2. Is ideal.

  The average cell diameter in the styrene resin foam obtained in the present invention is preferably 0.05 to 0.4 mm, more preferably 0.05 to 0.3 mm.

  In addition, in the case of a foam with a specific cell structure in which small bubbles with a bubble diameter of 0.25 mm or less and large bubbles with a bubble diameter of 0.3 to 1 mm are mixed, the obtained foam is cut to create a cross-sectional sample. The ratio of the area of small bubbles per unit cross-sectional area of the foam (occupied area ratio per unit cross-sectional area) (hereinafter referred to as small-cell area ratio) is preferably 10 to 90%, more preferably 20 to 90. %, Particularly preferably 25 to 80%, most preferably 30 to 70%.

  The method for producing a styrenic resin foam of the present invention includes mixing a methacrylic acid-modified polystyrene resin and a styrene resin with a flame retardant, a processing aid, a stabilizer, and, if necessary, a water-absorbing substance and other additives. The mixture is supplied to an extruder, heated and melted, and further mixed and kneaded together with a press-fitted foaming agent at a high temperature and high pressure in the extruder to obtain a styrene-based resin melt composition, which is suitable for extrusion foaming with a cooler or the like. It is manufactured by cooling to the resin temperature, extruding and foaming the fluid gel through a slit die into a low pressure region to form a foam, and foaming it into a plate shape.

  Regarding a method of mixing a halogen-based flame retardant with a methacrylic acid-modified polystyrene resin and a styrene-based resin and, if necessary, other additives, for example, a halogen-based flame retardant after heating and melting the methacrylic acid-modified polystyrene resin and the styrene resin Add other additives as necessary, mix halogenated flame retardant in methacrylic acid modified polystyrene resin and styrene resin, and mix other additives as necessary, then prepare a composition that is heated and melted However, another method such as supplying to an extruder and melting by heating may be used.

  There are no particular restrictions on the heating temperature, melt kneading time, and melt kneading means when the methacrylic acid-modified polystyrene resin or styrene resin and an additive such as a foaming agent are heated and melt kneaded. The heating temperature may be equal to or higher than the temperature at which the methacrylic acid-modified polystyrene resin and the styrene resin to be used are melted, but the temperature at which molecular degradation of the resin due to the influence of a flame retardant is suppressed as much as possible, for example, about 160 to 230 ° C. Is preferred. Melt-kneading time varies depending on the amount of extrusion per unit time, melt-kneading means, etc., and thus cannot be determined unconditionally. Time is appropriately selected. Examples of the melt-kneading means include a screw type extruder, but there is no particular limitation as long as it is used for normal extrusion foaming. However, in order to suppress the molecular degradation of the resin as much as possible, it is preferable to use a low shear type screw for the screw shape.

  With regard to the foam molding method, for example, an extrusion mold in which a foam obtained by releasing pressure from a slit die whose opening used for extrusion molding has a straight slit shape is placed in close contact with or in contact with the slit die. A method of molding a plate-like foam having a large cross-sectional area using a mold and a molding roll installed adjacent to the downstream side of the molding die is used. Further, a method of obtaining a desired foam cross-sectional shape, foam surface property, and foam quality by adjusting the flow surface shape of the extrusion mold and the mold temperature is used.

  The thickness of the foam of the present invention is not particularly limited and is appropriately selected depending on the application. For example, in the case of a heat insulating material used for a building material or the like, in order to give a preferable heat insulating property, bending strength and compressive strength, the thickness is not as thin as a sheet but as a normal plate. Is preferable, usually 10 to 150 mm, preferably 20 to 100 mm.

Further, the density of the foam of the present invention is preferably lightweight and excellent heat insulating properties and bending strength, in order to allowed to impart compressive strength is 25~45kg / m ^3, in 28~40kg / m ³ More preferably.

  Next, although the styrenic resin foam of this invention and its manufacturing method are demonstrated in detail based on an Example, this invention is not restrict | limited only to this Example. Unless otherwise specified, “parts” represents parts by weight, and “%” represents% by weight.

  As the characteristics of the foams obtained in Examples 1 to 5 and Comparative Examples 1 to 3 shown below, the foam density, average cell diameter, small cell occupation area ratio, compressive strength, 90 ° C. heat resistance (90 ° C., 24 hours) The foam volume change rate after heating), the foam thermal conductivity, and the flame retardance were examined according to the following methods.

1) 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 )
2) Average bubble diameter (mm)
The bubble diameter in each direction was measured according to ASTM D-3576.

  The cross section in the width direction of the foam is magnified and projected 50 to 100 times, and the bubble diameter (HD) in the thickness direction and the bubble diameter (TD) in the width direction are measured. Next, the cross section in the extrusion direction was enlarged and projected, and the bubble diameter (MD) in the extrusion direction was measured.

The average bubble diameter was calculated from the following formula by taking the cube of the product of the cell diameters in each direction.
Average bubble diameter = (HD x TD x MD) ^1/3
3) Small bubble occupation area ratio (%)
When the large and small bubbles constituting the foam are distributed in a sea-island shape, the occupied area ratio per cross-sectional area of the foam for the bubbles smaller than the bubble diameter of 0.25 mm was defined as the small bubble occupied area ratio. Here, the bubble having a bubble diameter smaller than 0.25 mm is a bubble having a circle equivalent diameter smaller than 0.25 mm.

4) Compressive strength (N / cm ² )
About the foam which passed 7 days after manufacture, the compressive strength (compressive strength of a product thickness direction) of a foam product was measured. A sample size of 25 mm × 50 mm × 50 mm was cut out and measured from an arbitrary position of the foam product, and the average value of n = 3 was obtained. The measuring method was according to JIS A 9511 extrusion method polystyrene foam heat insulating plate.

5) 90 ° C. heat resistance (foam volume change rate after heating at 90 ° C. for 24 hours) (%)
After 14 days from the production, the foam was cut into a thickness of 25 mm, a width and a length of 100 mm, heated in a hot air dryer at 90 ° C. for 24 hours, and the volume change rate before and after heating was shown.

6) Thermal conductivity of foam (W / mK)
It measured according to JIS A9511 about the foam which passed 30 days after manufacture.

7) Flame retardancy The foam which had passed 7 days after production was measured according to JIS A9511.
The inside of the JIS standard is “◯”, and the outside of the JIS standard is “×”.

8) Resin temperature at the time of passing through the slit die The resin temperature at the time of passing through the slit die means that a thermocouple sensor having a tip shape of about φ8 × 10mm is installed in the resin flow part closest to the upstream side of the slit die. The sensor is brought into contact with and the resin temperature is measured.

9) Extrusion mold temperature Extrusion mold temperature refers to the mold surface temperature of the resin flow surface in a molding mold in which a foam obtained by releasing pressure from the slit die is placed in close contact with or in contact with the slit die. The value measured using the contact-type thermometer used for the measurement of the stationary surface provided with the thermocouple sensor of part shape (phi) 25x40mm. The mold surface temperature is measured by bringing a sensor into contact with the mold surface at a portion close to the portion where the foamed resin flows (within 5 cm from the endmost portion of the foamed resin flowing portion) during foam molding.

Example 1
PS Japan Co., Ltd., trade name: G9401 (MFR = 2.3 g / 10 min) as styrene homopolymer, methacrylic acid modified polystyrene resin, PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7) %, MFR = 1.2 g / 10 min), and a styrene homopolymer / methacrylic acid modified polystyrene is mixed at a weight ratio of 75/25 to obtain a styrene base resin. As a halogen-based flame retardant, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, 0.2 part of talc as a nucleating agent, 0.25 part of barium stearate as a lubricant, As an additive, 1.0 part of bentonite is dry blended, and the resulting resin mixture is pressed in tandem. It was supplied to the machine. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. Thereafter, the mixture is cooled while being kneaded by a second extruder connected, and further by a cooler, and the foamed resin is extruded and foamed into the atmosphere at a temperature of about 110 to 130 ° C. from a slit die provided at the tip of the cooler. Then, plate molding was performed using an extrusion mold placed in close contact with the slit die and a molding roll placed downstream thereof.
By adjusting the temperature of the extrusion mold with oil temperature using a mold temperature controller and setting the temperature to 80 ° C., an extruded foam plate having a good surface condition, a thickness of about 40 mm, and a width of about 200 mm was obtained.

The obtained foam has a foam density of 32 kg / m ³ and an average cell diameter of 0.18 mm. It had a bubble structure in which large bubbles and small bubbles were mixed, and the occupied area ratio of small bubbles was 30%. The obtained foam has a compressive strength of 31 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 2.1%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change rate) was + 9.3%, the foam thermal conductivity was 0.027 W / mK, and the flame retardancy met the standards of JIS A 9511.

(Example 2)
PS Japan Co., Ltd., trade name: G9401 (MFR = 2.3 g / 10 min) as styrene homopolymer, methacrylic acid modified polystyrene resin, PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7) %, MFR = 1.2 g / 10 min), and a styrene homopolymer / methacrylic acid modified polystyrene is mixed at a weight ratio of 50/50 to obtain a styrene base resin. As a halogen-based flame retardant, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, 0.2 part of talc as a nucleating agent, 0.25 part of barium stearate as a lubricant, As an additive, 1.0 part of bentonite is dry blended, and the resulting resin mixture is pressed in tandem. It was supplied to the machine. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. Thereafter, the mixture is cooled while being kneaded by a second extruder connected, and further by a cooler, and the foamed resin is extruded and foamed into the atmosphere at a temperature of about 110 to 130 ° C. from a slit die provided at the tip of the cooler. Then, plate molding was performed using an extrusion mold placed in close contact with the slit die and a molding roll placed downstream thereof.

  An extrusion foam plate having a cross-sectional shape having a thickness of about 40 mm and a width of about 200 mm was obtained by adjusting the temperature of the extrusion mold to an oil temperature using a mold temperature controller and setting the temperature to 85 ° C.

The obtained foam has a foam density of 32 kg / m ³ and an average cell diameter of 0.19 mm. It had a bubble structure in which large bubbles and small bubbles were mixed, and the occupied area ratio of small bubbles was 25%. The resulting foam has a compressive strength of 32 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 1.0%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change rate) was + 5.4%, the foam thermal conductivity was 0.027 W / mK, and the flame retardancy met the standards of JIS A 9511.

(Example 3)
Styrene homopolymer was not mixed and styrene was used as a methacrylic acid modified polystyrene resin by using 100% by weight of PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7%, MFR = 1.2 g / 10 min). Base resin, 100 parts of styrene base resin, 4.0 parts of halogenated flame retardant, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, talc as nucleating agent 0.2 parts, 0.25 parts of barium stearate as a lubricant, and 1.0 parts of bentonite as other additives were dry blended, and the resulting resin mixture was fed to a tandem extruder. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. Then, after cooling while kneading in the second extruder connected, further cooler, after extrusion foaming to the atmosphere at a foamed resin temperature of about 110-130 ° C. from the slit die provided at the tip of the cooler, Plate molding was performed using an extrusion mold placed in close contact with the slit die and a forming roll placed downstream thereof.
By setting the temperature of the extrusion mold to 90 ° C. by adjusting the oil temperature using a mold temperature controller, an extruded foam plate having a good surface condition, a thickness of about 40 mm, and a width of about 200 mm was obtained.

The obtained foam has a foam density of 32 kg / m ³ and an average cell diameter of 0.19 mm. It had a bubble structure in which large bubbles and small bubbles were mixed, and the occupied area ratio of small bubbles was 25%. The obtained foam has a compressive strength of 34 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 0.1%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change rate) was + 1.4%, the foam thermal conductivity was 0.027 W / mK, and the flame retardancy met the standards of JIS A 9511.

Example 4
Styrene homopolymer was not mixed and styrene was used as a methacrylic acid modified polystyrene resin by using 100% by weight of PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7%, MFR = 1.2 g / 10 min). Base resin, 100 parts of styrene base resin, 3.5 parts of hexabromocyclododecane as halogen flame retardant, 0.2 part of talc as nucleating agent, 0.25 barium stearate as lubricant Parts were dry blended, and the resulting resin mixture was fed to a tandem extruder. The resin mixture supplied to the first extruder is melted and kneaded by heating to about 200 ° C., and then 0.9 parts of i-butane, 2.1 parts of n-butane, 3.0 parts of dimethyl ether, dioxide dioxide 1.5 parts of carbon was pressed into the resin from a separate line near the tip of the first extruder. Thereafter, the mixture is cooled while being kneaded by a second extruder connected, and further by a cooler, and the foamed resin is extruded and foamed into the atmosphere at a temperature of about 110 to 130 ° C. from a slit die provided at the tip of the cooler. Then, plate molding was performed using an extrusion mold placed in close contact with the slit die and a molding roll placed downstream thereof.
By setting the temperature of the extrusion mold to 90 ° C. by adjusting the oil temperature using a mold temperature controller, an extruded foam plate having a good surface condition, a thickness of about 50 mm, and a width of about 250 mm was obtained.

The obtained foam has a foam density of 27 kg / m ³ and an average cell diameter of 0.32 mm. The resulting foam has a compressive strength of 29 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 0.3%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change rate) was + 2.5%, the foam thermal conductivity was 0.031 W / mK, and the flame retardancy met the standards of JIS A 9511.

(Example 5)
Styrene homopolymer was not mixed and styrene was used as a methacrylic acid modified polystyrene resin by using 100% by weight of PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7%, MFR = 1.2 g / 10 min). Base resin, 100 parts of styrene base resin, 3.5 parts of hexabromocyclododecane as halogen flame retardant, 0.2 part of talc as nucleating agent, 0.25 barium stearate as lubricant Parts were dry blended, and the resulting resin mixture was fed to a tandem extruder. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 1.2 parts of i-butane, 2.8 parts of n-butane, and 2.5 parts of dimethyl ether are used as a foaming agent. Each was press-fitted into the resin near the tip of the first extruder from a separate line. After that, it is cooled while kneaded with the second extruder connected, and further with a cooler, extruded and foamed into the atmosphere from a slit die provided at the tip of the cooler, and then placed in close contact with the slit die. Plate molding was performed using a mold and a molding roll installed on the downstream side.
By setting the temperature of the extrusion mold to oil temperature using a mold temperature controller and setting the temperature to 100 ° C., an extruded foam plate having a good surface condition, a thickness of about 35 mm, and a width of about 200 mm was obtained.

The obtained foam has a foam density of 40 kg / m ³ and an average cell diameter of 0.43 mm. The resulting foam has a compressive strength of 42 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 0.1%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change rate) was + 1.8%, the foam thermal conductivity was 0.030 W / mK, and the flame retardancy met the standard of JIS A 9511.

(Comparative Example 1)
No methacrylic acid-modified polystyrene resin is used, and styrene homopolymer is made of PS Japan Co., Ltd., trade name: G9401 (MFR = 2.3 g / 10 min) is used at 100% by weight to make a styrene base resin, and styrene 100 parts of the base resin, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, 0.2 parts of talc as a nucleating agent, as a lubricant 0.25 part of barium stearate and 1.0 part of bentonite as other additives were dry blended, and the resulting resin mixture was fed to a tandem extruder. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. Thereafter, the mixture is cooled while being kneaded by a second extruder connected, and further by a cooler, and the foamed resin is extruded and foamed into the atmosphere at a temperature of about 110 to 130 ° C. from a slit die provided at the tip of the cooler. ,
Plate molding was performed using an extrusion mold placed in close contact with the slit die and a forming roll placed downstream thereof.
An extrusion foam plate having a cross-sectional shape having a thickness of about 40 mm and a width of about 200 mm was obtained by adjusting the temperature of the extrusion mold to an oil temperature using a mold temperature controller and setting the temperature to 70 ° C.

The obtained foam has a foam density of 32 kg / m ³ and an average cell diameter of 0.18 mm. It had a bubble structure in which large bubbles and small bubbles were mixed, and the occupied area ratio of small bubbles was 30%. The obtained foam has a compressive strength of 30 N / cm ² , 80 ° C. heat resistance (80 ° C., foam volume change rate after 24 hours heating) is + 5.1%, 90 ° C. heat resistance (90 ° C., after 24 hours heating) The foam volume change ratio) was + 56.9%, which was a large value compared to the examples. The foam thermal conductivity was 0.027 W / mK, and the flame retardancy met the standard of JIS A 9511.

(Comparative Example 2)
Styrene homopolymer was not mixed and styrene was used as a methacrylic acid modified polystyrene resin by using 100% by weight of PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7%, MFR = 1.2 g / 10 min). Base resin, 100 parts of styrene base resin, 4.0 parts of halogenated flame retardant, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, talc as nucleating agent 0.2 parts, 0.25 parts of barium stearate as a lubricant, and 1.0 parts of bentonite as other additives were dry blended, and the resulting resin mixture was fed to a tandem extruder. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. After that, it is cooled while kneaded with the second extruder connected, and further with a cooler, extruded and foamed into the atmosphere from a slit die provided at the tip of the cooler, and then placed in close contact with the slit die. Plate molding was performed using a mold and a molding roll installed on the downstream side.
The mold temperature was adjusted to 70 ° C by adjusting the oil temperature using a mold temperature controller, and molding was attempted. However, there was a surface property failure phenomenon such as cracking on the foam surface, and molding was stable. No body was obtained.

(Comparative Example 3)
Styrene homopolymer was not mixed and styrene was used as a methacrylic acid modified polystyrene resin by using 100% by weight of PS Japan Co., Ltd., trade name: G9001 (methacrylic acid modification rate 7%, MFR = 1.2 g / 10 min). Base resin, 100 parts of styrene base resin, 4.0 parts of halogenated flame retardant, 4.0 parts of hexabromocyclododecane, 1.0 part of tris (tribromoneopentyl) phosphate, talc as nucleating agent 0.2 parts, 0.25 parts of barium stearate as a lubricant, and 1.0 parts of bentonite as other additives were dry blended, and the resulting resin mixture was fed to a tandem extruder. After the resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, 3.7 parts of i-butane, 2.0 parts of dimethyl ether, and 1.0 part of water are separately added as foaming agents. From this line, it was press-fitted into the resin near the tip of the first extruder. After that, it is cooled while kneaded with the second extruder connected, and further with a cooler, extruded and foamed into the atmosphere from a slit die provided at the tip of the cooler, and then placed in close contact with the slit die. Plate molding was performed using a mold and a molding roll installed on the downstream side.
The temperature of the extrusion mold was adjusted to 70 ° C by adjusting the oil temperature using a mold temperature controller, and molding was attempted. However, the foam surface softened and surface bubbles were broken, resulting in stability. Thus, a molded product could not be obtained.

  The results obtained in Examples 1-5 and Comparative Examples 1-3 are summarized in Table 1.

Claims (8)

A styrene resin foam obtained by heating and melting a styrene resin, adding a foaming agent, and extruding and foaming the styrene resin, and (A) by weight ratio, styrene homopolymer / methacrylic acid modified polystyrene = 75/25 After the styrene base resin containing 0/100 was melted by heating and the styrene resin melt composition mixed with the foaming agent was extruded and foamed, (B) the extrusion mold temperature (T ° C.) was changed to the styrene base material. In relation to HDT (t ° C.) at 1.82 MPa load of the resin, the foam density is controlled to satisfy the general formula (t−10) ≦ T ≦ (t + 25) 25 to 45 kg / A method of producing a styrene resin extruded foam having a thickness of 10 to 150 mm at m ³ .   2. The method for producing an extruded foam of styrene-based resin according to claim 1, wherein the volume change rate when the foam is heated at 90 [deg.] C. for 24 hours is -10% to + 10%.   The method for producing a styrene resin extruded foam according to claim 1 or 2, wherein the methacrylic acid modified polystyrene has a methacrylic acid modification rate of 3% to 10%.   The method for producing a styrene resin extruded foam according to any one of claims 1 to 3, wherein the MFR of methacrylic acid modified polystyrene is 1 to 5 g / 10 min.   The method for producing a styrene resin extruded foam according to any one of claims 1 to 4, wherein the foaming agent contains a saturated hydrocarbon having 3 to 5 carbon atoms and an ether.   The method for producing a styrene resin extruded foam according to claim 5, wherein the foaming agent contains another non-halogen foaming agent.   The bubbles forming the foam are mainly composed of bubbles having a bubble diameter of 0.25 mm or less and bubbles having a bubble diameter of 0.3 to 1 mm. These bubbles are dispersed in a sea-island shape through the cell membrane, and the bubble diameter is 0. 0 mm. The method for producing a styrene resin extruded foam according to any one of claims 1 to 6, wherein bubbles of 25 mm or less have an occupied area ratio of 10 to 90% per foam cross-sectional area.   The method for producing a styrene resin extruded foam according to any one of claims 1 to 7, wherein the foam has a thermal conductivity of 0.034 W / mK or less.