JP2012229288A - Extruded styrene resin foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extruded styrene resin foam which is light in weight and excellent in mechanical strength.SOLUTION: The extruded styrene resin foam is obtained by extrusion foaming of a foamable molten resin composition prepared by melt-kneading a styrene resin mixture and a foaming agent, wherein the styrene resin mixture comprises a mixture of (A) 90-98 pts.wt. of a styrene resin and (B) 2-10 pts.wt. of an ethylene copolymer having a carbonyl group [the total of (A) and (B) is 100 pts.wt.], and the foaming agent comprising 10 to <60 mol% of carbon dioxide and 90 mol% or less and >40 mol% of another physical foaming agent, relative to the amount of all the foaming agents is used as the above foaming agent.

Description

  The present invention relates to a styrene resin foam by an extrusion foaming method and a method for producing the same. More specifically, the present invention relates to a styrene resin extruded foam having excellent environmental compatibility, light weight and excellent strength properties, and a method for producing the same.

  As a method for producing a styrene resin extruded foam, extrusion foam molding is known. In extrusion foam molding, a styrene resin extruded foam is prepared by heating and melting a styrene resin composition using an extruder, etc., then adding a foaming agent, cooling to a predetermined resin temperature, and extruding it to a low pressure region. Is manufactured continuously.

  Styrenic resin extruded foam is used as, for example, a heat insulating material for a structure because of good workability and heat insulating properties. Moreover, since it has public mechanical strength, it is used for construction materials such as embankment materials and underground embedding agents, and civil engineering materials.

  On the other hand, chlorofluorocarbons and saturated hydrocarbons have been conventionally used as foaming agents for styrene-based resin extruded foams in order to obtain excellent heat insulation properties, and good mechanical properties, foam dimensional stability and In order to obtain productivity, halogenated hydrocarbons represented by methyl chloride and ethyl chloride, which are easily permeable gases, are used in combination with styrene resins. However, in recent years, environmental issues such as ozone layer destruction, global warming, and the influence of chemical substances on the atmosphere and water quality have been highlighted. For example, chlorofluorocarbons are regulated substances as ozone-depleting substances and global warming substances, and their use is difficult. In addition, methyl chloride and ethyl chloride are required to be reported as Class 1 Designated Substances under the PRTR Law, and the amount of emissions is managed. Therefore, it is desirable to use a foaming agent that is as environmentally friendly as possible. Against this background, studies have been made using carbon dioxide as a foaming agent that has a low environmental impact and high safety.

  However, when carbon dioxide is used as the main component as a foaming agent, carbon dioxide has a lower solubility in polystyrene than fluorocarbons and saturated hydrocarbons. From this, gas is ejected or voids are generated, and a good foam cannot be obtained. Therefore, it is necessary to keep the resin pressure high, for example, by narrowing the gap between the die lips. In this case, there is a problem that a foam having a large thickness cannot be obtained.

In order to overcome such problems, Patent Document 1 discloses a resin composition obtained by adding a crosslinked resin (crosslinked ethylene-vinyl acetate) obtained by crosslinking a thermoplastic resin having a solubility coefficient of carbon dioxide to a specific value or more to a polystyrene resin. And its foams have been reported. However, the addition amount of the crosslinked ethylene-vinyl acetate is as large as 35 to 40 parts by weight with respect to 100 parts by weight of the polystyrene-based resin, and there is a defect that a foam excellent in mechanical strength cannot be obtained.
Patent Document 2 reports a method of adding an ethylene copolymer having a carbonyl group to a polystyrene resin having a specific molecular weight and molecular weight distribution. However, the density of the extruded foam plate obtained by this production method is 33.1 kg / m ³ even at the lightest, and a further higher expansion ratio is desired.

JP-A-6-32930 JP 2008-69200 A

  Under such circumstances, the problem to be solved by the present invention is to provide a styrene resin extruded foam that is lightweight and excellent in mechanical strength and a method for producing the same.

  As a result of intensive research in order to solve the above problems, the present inventors have determined that a styrene resin mixture comprising a mixture of a styrene resin and (B) an ethylene copolymer having a carbonyl group has a concentration of 10 moles of carbon dioxide. It has been found that a foam having a light weight and excellent mechanical strength can be obtained by foaming using a foaming agent comprising 90% by mole or more and less than 60% by mole and other physical foaming agents of 90% by mole or less and more than 40% by mole. The present invention has been completed.

That is, the present invention
[1] A styrene resin extruded foam obtained by extrusion foaming a foamable molten resin composition obtained by melt-kneading a styrene resin mixture and a foaming agent,
The styrene resin mixture is a mixture of (A) 90 to 98 parts by weight of a styrene resin and (B) 2 to 10 parts by weight of an ethylene copolymer having a carbonyl group [total of (A) and (B) is 100 weights. Part],
And as a foaming agent, the foaming agent which consists of carbon dioxide 10 mol% or more and less than 60 mol% with respect to the total amount of foaming agents, and other physical foaming agents 90 mol% or less and more than 40 mol% is used, It is characterized by the above-mentioned. Is.

[2] The ethylene-based copolymer having the carbonyl group is an ethylene-vinyl acetate copolymer.
[3] Examples of the other physical foaming agent include at least one selected from the group selected from water, ether and saturated hydrocarbons having 3 to 5 carbon atoms.
[4] The density of the foam is preferably 33 kg / m ³ or less.
[5] A process for producing a styrene resin extruded foam obtained by extrusion foaming a foamable molten resin composition obtained by melt-kneading a styrene resin mixture and a foaming agent,
The styrene resin mixture is a mixture of (A) 90 to 98 parts by weight of a styrene resin and (B) 2 to 10 parts by weight of an ethylene copolymer having a carbonyl group [total of (A) and (B) is 100 weights. Part],
And as a foaming agent, the foaming agent which uses 10-60 mol% of carbon dioxide with respect to the total amount of foaming agents and 90-40 mol% of other physical foaming agents is used, The styrene-type resin extrusion foaming characterized by the above-mentioned. It is a manufacturing method of a body.

  According to the present invention, it is possible to obtain a styrene-based resin extruded foam that is lightweight and excellent in mechanical strength.

  Embodiments of the present invention will be described below. In addition, this embodiment is only a part of this invention, and it cannot be overemphasized that this embodiment can be suitably changed in the range which does not change the summary of this invention.

  The styrene resin extruded foam of the present invention is a styrene resin extruded foam obtained by extrusion foaming a foamable molten resin composition obtained by melt-kneading a styrene resin mixture and a foaming agent.

In the case of using a foaming agent containing carbon dioxide, the styrene resin mixture which is a raw material resin used in the present invention has (A) a polystyrene resin and (B) in order to increase the foamability of the polystyrene resin extruded foam plate. It is a mixed resin made of an ethylene copolymer having a carbonyl group.
(B) By mixing an ethylene copolymer having a carbonyl group with (A) a polystyrene resin, gas separation from the resin in the die (foaming inside the die) is suppressed, and a good foam is obtained. can get.

  (A) Styrenic resin used in the present invention is not particularly limited, and styrene-based monomers such as styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, bromostyrene, chlorostyrene, vinyltoluene, and vinylxylene. A homopolymer of the body or a copolymer comprising a combination of two or more monomers, the styrene monomer and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, Examples thereof include a copolymer obtained by copolymerizing one or more monomers such as maleic anhydride and itaconic anhydride. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, maleic anhydride, and itaconic anhydride to be copolymerized with styrenic monomers are the compression strength of the styrene resin extrusion foam produced The amount can be used so as not to deteriorate the physical properties. Further, the styrene resin used in the present invention is not limited to the homopolymer or copolymer of the styrene monomer, but the homopolymer or copolymer of the styrene monomer and the other single monomer. It may be a blend of the polymer with a homopolymer or copolymer, and may be blended with diene rubber reinforced polystyrene or acrylic rubber reinforced polystyrene. Furthermore, the styrenic resin of the present invention may be a styrenic resin having a branched structure for the purpose of adjusting the melt flow rate (hereinafter referred to as MFR), the melt viscosity at the time of molding, the melt tension, and the like.

As the styrenic resin in the present invention, one having an MFR of 0.1 to 50 g / 10 min is excellent in molding processability at the time of extrusion foam molding, the discharge amount at the molding process, and the obtained thermoplasticity It is easy to adjust the thickness, width, density, or closed cell ratio of the resin foam to a desired value, and the foamability (the thickness, width, density, closed cell ratio, surface property, etc. of the foam is easily adjusted to the desired situation. Thermoplastic resin with a good balance of mechanical strength such as compressive strength, bending strength or amount of bending, and toughness, etc. This is preferable from the viewpoint of obtaining a foam. Further, the MFR of the styrenic resin is more preferably 0.3 g / 10 min or more and 40 g / 10 min or less from the viewpoint of balance between molding processability and foaming mechanical strength, toughness, etc., and 0.5 g / 10 min. It is particularly preferably 30 g / 10 min or less.
In the present invention, MFR is measured according to method A and test condition H of JIS K7210 (1999).

The styrenic resin used in the production method of the present invention may be a commercially available resin (so-called virgin resin) as long as the MFR conditions are satisfied, or recycled after being used for foam production or the like. It may be a resin recycled using an extruder or the like, a resin recovered in the market for food trays or fish boxes, or a mixture thereof.
In general, even when a recycled resin for food trays and fish boxes collected in the market with an MFR exceeding 20 g / 10 min is used, a foam having good surface properties can be obtained.

  In the present invention, among the styrenic resins described above, a polystyrene resin can be particularly suitably used from the viewpoint of economy and processability. Further, when high heat resistance is required for the extruded foam, it is preferable to use a styrene-acrylonitrile copolymer, (meth) acrylic acid copolymer polystyrene, or maleic anhydride-modified polystyrene. Moreover, when high impact resistance is calculated | required by an extrusion foam, it is preferable to use rubber reinforced polystyrene. These styrenic resins may be used alone, or two or more different styrenic resins such as copolymerization component, molecular weight, molecular weight distribution, branched structure, and MFR may be mixed and used.

  Examples of the ethylene-based copolymer (B) having a carbonyl group used in the present invention include copolymers of ethylene and vinyl esters, acrylic esters, other acrylic compounds, and the like. -Vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methacrylic acid copolymer , Ethylene-methacrylic acid copolymers, ethylene-acrylic acid copolymers such as ethylene-glycidyl methacrylate, ethylene-acrylic acid copolymers, and some intermolecular molecules of ethylene-methacrylic acid copolymers are metal ions Ionomer, maleic acid modified polyethylene, maleic acid modified ethylene Ethyl acrylic acid copolymer, and the like.

  (B) Among ethylene-based copolymers having a carbonyl group, an ethylene-vinyl acetate copolymer is preferable from the viewpoint of a large foam-suppressing effect inside the die.

  (B) The content of the compound having a carbonyl group such as vinyl acetate, methacrylic acid or methyl methacrylate in the ethylene-based copolymer having a carbonyl group is 5 to 50% by weight with respect to the copolymer. It is preferable that it is 10 to 30% by weight. When the content of the compound having a carbonyl group is within the above range, the dispersibility of the copolymer in a polystyrene resin is improved, so that a good foam can be obtained, which is preferable.

  (B) The MFR of the ethylene-based copolymer having a carbonyl group is preferably 0.3 g / 10 min or more and 30 g / 10 min or less from the viewpoint of balance between molding processability and foaming mechanical strength, toughness, 1 g / 10 min or more and 20 g / 10 min or less is more preferable.

  (B) The mixing ratio of the ethylene copolymer having a carbonyl group is 2 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the entire raw material resin including the styrene resin. More preferably, it is 3 to 7 parts by weight. (B) When the mixing ratio of the ethylene-based copolymer having a carbonyl group is less than 2 parts by weight, the effect of suppressing the foaming in the die is small, and molding tends to be poor, or it is difficult to increase the foaming ratio. . On the other hand, when the mixing ratio exceeds 10 parts by weight, the mechanical strength of the obtained foam tends to decrease.

  The foaming agent used in the present invention is composed of 10 mol% or more and less than 60 mol% of carbon dioxide and 90 mol% or less and more than 40 mol% of other physical foaming agents with respect to the total amount of the foaming agent. When the content of carbon dioxide is 60 mol% or more, there is a tendency that a lightweight foam is difficult to obtain. From this viewpoint, the content of carbon dioxide is preferably 15 mol% or more and less than 60 mol%, and more preferably 20 to 50 mol%.

  The amount of carbon dioxide used is preferably 1 to 4 parts by weight, more preferably 1.5 to 3.5 parts by weight, based on 100 parts by weight of the styrene resin. When the amount of carbon dioxide used is less than 1 part by weight, it tends to be difficult to increase the expansion ratio. When the amount of carbon dioxide used exceeds 4 parts by weight, the dispersion and absorption in the styrene-based resin exceed the allowable range, gas ejection from the die, and the like tend to be impossible to obtain. .

  As a foaming agent other than carbon dioxide used in the present invention, (i) from at least one selected from the group consisting of water, (b) ether, and (c) a saturated hydrocarbon having 3 to 5 carbon atoms. Can be used in combination. By using these foaming agents in combination, it is possible to reduce the weight of the foam more stably, and it is effective for further improving the quality of the foam with heat insulation and dimensional stability.

When (i) water is used as the other foaming agent, the amount of water used is the raw material resin (styrene-based resin mixture) 100 from the viewpoint of obtaining a foam of good quality such as stable foam production and appearance. 0.1-2 weight part is preferable with respect to a weight part, and 0.2-1.5 weight part is more preferable.
If the amount of water used is less than 0.1 part by weight, it tends to be difficult to increase the expansion ratio. When the amount of water used exceeds 2 parts by weight, the dispersion and absorption in the styrene resin exceed the allowable range, and gas ejection from the die tends to occur, and a good foam tends not to be obtained. .

Examples of (b) ether as other foaming agent 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.
When (ro) ether is used as the other blowing agent, the amount of ether used is preferably 0.1 to 4 parts by weight, or not used, with respect to 100 parts by weight of the raw material resin (styrene-based resin mixture). It is more preferable to set it as 1-3.5 weight part.

  Examples of the (C) saturated hydrocarbon having 3 to 5 carbon atoms as other blowing agents include propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and the like. Among the saturated hydrocarbons having 3 to 5 carbon atoms, n-butane, i-butane, and a mixture of n-butane and i-butane are preferable, and n-butane is particularly preferable from the viewpoint of foamability and thermal insulation performance of the foam. And i-butane.

  When (C) a saturated hydrocarbon having 3 to 5 carbon atoms is used as the other blowing agent, the amount of the saturated hydrocarbon used is 0.1 to 4 with respect to 100 parts by weight of the raw material resin (styrene-based resin mixture). Part by weight or not used is preferable, and 0.5 to 2.5 parts by weight is more preferable.

  In the present invention, by using a foaming agent other than (i) to (c) as the other foaming agent, a plasticizing effect and an auxiliary foaming effect at the time of foam production can be obtained, and the extrusion pressure is reduced and stably. The foam can be manufactured. However, the amount of foaming agent other than (a) to (c) may be limited depending on the properties of the foam, such as the desired foaming ratio and flame retardancy. May not be sufficient.

  As foaming agents other than (i) to (c), dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl n-propyl ketone, methyl-n-butyl ketone, methyl-i-butyl ketone, methyl-n-amyl ketone, methyl-n- Ketones such as hexyl ketone, ethyl-n-propyl ketone, ethyl-n-butyl ketone; 1 to carbon atoms such as methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol 4 saturated alcohols; carboxylic acid esters such as formic acid methyl ester, formic acid ethyl ester, formic acid propyl ester, formic acid butyl ester, formic acid amyl ester, propionic acid methyl ester, propionic acid ethyl ester; methyl chloride, ethyl chloride, etc. Halogenated alkyl, organic foaming agents such as inorganic foaming agents, such as nitrogen, azo compounds, etc. can be used chemical blowing agents such as tetrazoles. These other blowing agents may be used alone or in combination of two or more.

  In the present invention, the total amount of the foaming agent used relative to the raw material resin (styrene resin mixture) is preferably 4 to 10 parts by weight with respect to 100 parts by weight of the styrene resin composition. By setting the total amount of the foaming agent in the above range, a lightweight foam can be stably produced.

  In the present invention, when water is used as a foaming agent, it is preferable to add a water-absorbing substance in order to stably perform extrusion foam molding. A water-absorbing substance refers to a compound that absorbs water, absorbs, adsorbs, swells with water, or a compound that reacts with water to form a hydrate. The water-absorbing material absorbs, adsorbs, or reacts with water having low compatibility with the styrene resin to form a gel, and is uniformly dispersed in the styrene resin in the gel state. It is considered that stable extrusion foaming can be realized without causing any voids or voids.

  Specific examples of the water-absorbing substance used in the present invention include an anhydrous silica (silicon oxide) having a silanol group on the surface [for example, AEROSIL manufactured by Nippon Aerosil Co., Ltd. is commercially available] and the like. Water-absorbing or water-swelling layered silicates such as fine powder having a particle diameter of 1000 nm or less, smectite, and swellable fluorine mica, and organically treated products thereof; zeolite, activated carbon, alumina, silica gel, porous glass, activated clay Porous materials such as diatomaceous earth; sulfates such as sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, barium sulfate, aluminum sulfate, zinc sulfate, ammonium sulfate; sodium carbonate, sodium bicarbonate, magnesium carbonate, ammonium carbonate Carbonates such as sodium phosphate and phosphate Phosphates such as nesium, aluminum phosphate, ammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, triammonium phosphate, calcium dihydrogen phosphate, calcium hydrogen phosphate, Calcium salt, trisodium citrate, tripotassium citrate, calcium lactate, ammonium oxalate, potassium oxalate, disodium succinate, sodium acetate, sodium pyrophosphate, magnesium chloride, barium chloride and other metal salts, boron oxide, boron Boron compounds such as sodium acid, polyacrylate polymer, starch-acrylic acid graft copolymer, polyvinyl alcohol polymer, vinyl alcohol-acrylate copolymer, ethylene-vinyl alcohol copolymer, Polyacrylonitrile Methacrylic acid methyl - butadiene copolymer, such as water-absorbing polymers such as polyethylene oxide copolymer and derivatives thereof. A water absorbing substance may be used independently and may use 2 or more types together.

  The amount 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 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin composition. Preferably it is 0.1-8 weight part, More preferably, it is 0.2-7 weight part. When the content of the water-absorbing substance is less than 0.1 parts by weight, the effect of stabilizing the water dispersion by the water-absorbing substance is insufficient, and pores and voids are generated due to poor water dispersion in the extruder, leading to defective foam. There is a case. On the other hand, if the amount exceeds 10 parts by weight, poor dispersion of the water-absorbing substance in the extruder may occur, resulting in bubble unevenness, which may lead to foam failure, deterioration of the heat insulation performance of the foam, variation in quality, etc. Problems such as enlargement may occur.

  In this invention, a flame retardance can be provided to the styrene resin foam obtained by containing a halogenated flame retardant as a flame retardant.

  Specific examples of the halogen-based flame retardant used in the present invention include halogenated alicyclic compounds such as hexabromocyclododecane, tetrabromocyclooctane, and chloropentabromocyclohexane, hexabromobenzene, pentabromotoluene, and ethylene bispenta Bromodiphenyl, decabromodiphenyl ether, 2,3-dibromopropylpentabromophenyl ether, bis (2,4,6-tribromophenoxy) ethane, tetrabromophthalic anhydride, octabromotrimethylphenylindane, pentabromobenzyl acrylate, tribromo Halogenated aromatic compounds such as phenyl allyl ether or derivatives thereof, tetrabromobisphenol-A, tetrabromobisphenol-S, tetrabromobisphenol-F, tetra Lomobisphenol-A-bis (2,3-dibromopropyl ether), tetrabromobisphenol-S-bis (2,3-dibromopropyl ether), tetrabromobisphenol-F-bis (2,3-dibromopropyl ether), Tetrabromobisphenol-A-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-S-bis (2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-F-bis ( 2,3-dibromo-2-methylpropyl ether), tetrabromobisphenol-A-diallyl ether, tetrabromobisphenol-S-diallyl ether, tetrabromobisphenol-F-diallyl ether, and the like, and derivatives thereof And the like. These substances may be used alone or as a mixture.

  In particular, hexabromocyclododecane, tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether, tetrabromobisphenol A-bis (2,3-dibromopropyl) ether, tris (2,3-dibromo Propyl) isocyanurate is preferably used for reasons such as good extrusion operation and no adverse effects on the heat resistance of the foam.

  The content of the halogen flame retardant in the present invention is such that the flammability specified in JIS A9511 can be obtained, and that the thermal stability of the styrene resin can be maintained in the extruder during foam production. Although it is appropriately adjusted according to the type of fuel, the amount of foaming agent added, the density of the foam, and depending on the case, the type or amount of other additives, it is generally about 100 parts by weight of the raw material resin (styrene-based resin mixture). On the other hand, 0.2-5 weight part is preferable, More preferably, it is 1-3 weight part. If the content of the halogen-based flame retardant is less than 0.2 parts by weight, good properties as a foam such as flame retardancy tend to be difficult to obtain. On the other hand, if the content exceeds 5 parts by weight, foam production The stability and surface properties of the time may be impaired. However, the content of the halogen-based flame retardant is the kind of additive such as foaming agent addition amount, foam density, additive having a flame retardant synergistic effect or the like so that the flame retardancy specified in JIS A9511 measuring method A can be obtained. It is more preferable to adjust appropriately according to the addition amount.

  In the present invention, for the purpose of improving the flame retardancy of the styrenic resin foam, a flame retardant aid exhibiting a synergistic effect with the flame retardant described above may be added. Examples of the flame retardant aid that exhibits a synergistic effect with the flame retardant include iron-containing compounds, phosphorus-containing compounds, nitrogen-containing compounds, boron-containing compounds, sulfur-containing compounds, and the like. Specifically, iron oxide, phosphorus-containing compounds, Nitrogen compounds, boron-containing compounds, sulfur-containing compounds (aromatic sulfonic acid compounds) and the like may be used. Among these, from the viewpoint of flame retardancy, iron oxide as the iron-containing compound, triphenyl phosphate and tris (tribromoneopentyl) phosphate as the phosphorus-containing compound, cyanuric acid, isocyanuric acid and their derivatives, boron-containing compounds as the nitrogen-containing compound Most preferred are boron oxide as the sulfur-containing compound and sulfanilic acid as the sulfur-containing compound and derivatives thereof. In addition, as a cyanuric acid derivative and an isocyanuric acid derivative, the thing of Unexamined-Japanese-Patent No. 2002-30174 ([0069] paragraph-[0079] paragraph) can be used, for example.

  The content of the flame retardant auxiliary that exhibits a synergistic effect with the halogen flame retardant depends on the type of the flame retardant auxiliary that exhibits a synergistic effect with the halogen flame retardant, but with respect to 100 parts by weight of the raw material resin (styrene resin mixture), 0.0001 to 5 parts by weight is preferred.

  In the present invention, various inorganic substances such as silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calcium carbonate and the like, as long as they do not inhibit the effects of the present invention. Compounds, processing aids such as sodium stearate, magnesium stearate, barium stearate, liquid paraffin, olefin wax, stearylamide compound, phenolic antioxidant, phosphorus stabilizer, nitrogen stabilizer, sulfur stabilizer It may contain additives such as a light-resistant stabilizer such as an agent, a benzotriazole, a hindered amine, a flame retardant other than the above, an antistatic agent, and a colorant such as a pigment.

  As a procedure for adding various additives to the styrene-based resin, for example, after adding and mixing various additives to the raw resin (styrene-based resin mixture), the mixture is supplied to an extruder, heated and melted, and further a foaming agent. The timing of adding various additives to the styrenic resin and the kneading time are not particularly limited.

  The heating temperature of the raw material resin (styrene-based resin mixture) may be higher than the temperature at which the styrene-based resin to be used melts, but the temperature at which molecular degradation of the resin due to the influence of additives and the like is suppressed as much as possible, for example 150 About ~ 260 degreeC is preferable. The melt-kneading time varies depending on the amount of styrene-based resin extruded per unit time and the type of extruder used as the melt-kneading means, so it cannot be uniquely defined. The styrene-based resin and the blowing agent or additive are uniform. The time required for the dispersion and mixing is appropriately set.

  Examples of the melt-kneading means include a screw type extruder, but are not particularly limited as long as they are used for ordinary extrusion foaming. However, in order to suppress the molecular deterioration of the resin as much as possible, the screw shape of the extruder is preferably a low shear type.

  The foam molding method is, for example, that an extruded foam obtained by opening from a high pressure region to a low pressure region through a slit die having a linear slit shape used for extrusion molding is in close contact with or in contact with the slit. A method of forming a ten thousand foam having a large cross-sectional area is used, using a molding die installed in the middle and a molding roll installed adjacent to the downstream side of the molding die. By adjusting the flow surface shape of the molding die and the mold temperature, the desired cross-sectional shape of the foam, the surface property of the foam, and the quality of the foam can be obtained.

  When considering that the styrene resin extruded foam according to the present invention functions as, for example, a heat insulating material for buildings, a cold storage or a cold car, the thermal conductivity measured according to JIS A9511 is 0. It is preferable that it is 040 W / mK or less.

The styrene-based resin extruded foam according to the present invention has a density of the foam from the viewpoint of heat insulation and lightness considering that it functions as, for example, a heat insulator for a building, a cold storage, or a cold car. It is preferably 20 to 60 kg / m ³ , more preferably 20 to 40 kg / m ³ , and particularly preferably 25 to 33 kg / m ³ .

  The thickness of the styrene-based resin extruded foam according to the present invention is not particularly limited, but for example, heat insulation, bending strength, and compressive strength in consideration of functioning as a heat insulator for a building, a cold storage, or a cold car. From this viewpoint, the thickness is preferably 10 to 150 mm, more preferably 15 to 120 mm, and particularly preferably 20 to 100 mm.

  Thus, according to the present invention, it is possible to easily obtain a styrene resin extruded foam that is lightweight and excellent in mechanical strength.

  Examples of the present invention will be described below. Needless to say, the present invention is not limited to the following examples. In the following examples and comparative examples, “%” represents “% by weight” unless otherwise specified.

The raw materials used in the examples and comparative examples are as follows.
(A) ResinPolystyrene (PS) [manufactured by PS Japan, G9401, MFR: 2.2 g / 10 min]
● Ethylene-vinyl acetate copolymer (EVA1) [Mitsui DuPont Polychemical Co., Ltd., EVAFLEX EVA560, vinyl acetate content: 14%, MFR: 3.5 g / 10 min]
● Ethylene-vinyl acetate copolymer (EVA2) [Mitsui / Dupont Polychemical Co., Ltd., EVAFLEX EVA260, vinyl acetate content: 28%, MFR: 6 g / 10 min]
(B) Halogen flame retardant Hexabromocyclododecane [manufactured by Albemarle, HP900]
Tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether [Daiichi Kogyo Seiyaku Co., Ltd., Pyroguard SR-130]
(C) Other additives
● Talc [Made by Hayashi Kasei Co., Ltd., Talcan Powder PK-Z]
● Calcium stearate [manufactured by Sakai Chemical Co., Ltd., SC-P]
● Bentonite [Wilver Ellis Co., Ltd., Gel White H]
(D) Foaming agent ● Carbon dioxide [made by Showa Carbon Dioxide Co., Ltd.]
● Water [tap water]
● Dimethyl ether [manufactured by Sumitomo Seika Co., Ltd.]
● Isobutane [Mitsui Chemicals, Inc.]
● Normal butane [Mitsui Chemicals, Inc.]

  About an Example and a comparative example, extrusion stability and moldability, foam thickness, foam density, average cell diameter, plane compressive strength, thermal conductivity, and combustibility were evaluated according to the following methods.

(1) Extrusion stability and moldability Stability and moldability when extruded and foamed continuously for 1 hour were evaluated according to the following criteria.
◯: There is no gas blowout from the die and no pressure fluctuation, and a foam having a constant cross-sectional shape can be molded stably. And a foam with no voids and a good surface condition can be obtained.
X: A foam having a certain cross-sectional shape cannot be molded due to gas blowout from the die or pressure fluctuation. Even if the foam can be molded, it is a foam having pores or a poor surface condition.

(2) Foam thickness (mm)
The thickness of the obtained styrene resin extruded foam was measured using calipers.

(3) Whole foam density (kg / m ³ )
The obtained styrene-based resin extruded foam was cut into a rectangular parallelepiped shape of about 300 mm (extrusion direction) × 120 mm (width direction) × 25 mm (thickness direction), measured for weight, and using vertical calipers, The horizontal dimension and the height dimension were measured.
From the measured weight and each dimension, the foam density was determined based on the following formula.
Foam overall density (kg / m ³ ) = foam weight (kg) / foam volume (m ³ )

(4) Average cell diameter The cell diameter in each direction of the thickness direction, the width direction, and the extrusion direction in the obtained styrene resin extruded foam was measured according to ASTM D-3576.
That is, the cross-section in the width direction of the obtained foam is enlarged and projected 50 to 100 times, and the average cell diameter (HD) in the thickness direction and the average cell diameter (TD) in the width direction are measured. Next, the cross section in the extrusion direction was enlarged and projected, and the average cell diameter (MD) in the extrusion direction was measured.
The average bubble diameter was calculated from the following equation, with the product of the average bubble diameter in each direction as the third root.
Average bubble diameter = (HD x TD x MD) ^1/3

(5) Plane compressive strength (N / cm ² )
About the styrene resin extrusion foam which passed 4 days after manufacture, three samples of thickness 25mm x width 55mm x length (extrusion direction) 55mm were cut out in arbitrary positions, and it turned into JIS A9511 (extrusion method polystyrene foam heat insulation board). According to the prescribed measurement method, the thickness direction degree of the foam and the compressive strength (N / cm ² ) in the extrusion direction were measured, and the average value was obtained.

(6) Thermal conductivity (W / mK)
The thermal conductivity of the styrene resin extruded foam 30 days after the production was measured according to JIS A9511.

(7) Foam flammability The styrene-based resin extruded foam after 4 days from the production was measured according to JIS A9511.
In addition, the measurement cut out five test pieces about one foam, and evaluated it with the following evaluation criteria.
○: All specimens disappear within 3 seconds and do not burn beyond the combustion limit indicator line.
Δ: The average burning time of the five test pieces is within 3 seconds, but one or more test pieces do not disappear within 3 seconds. However, combustion does not exceed the combustion limit indicator line.
X: The average burning time of 5 test pieces exceeds 3 seconds. Or it burns exceeding the combustion limit indicating line.

Example 1
3 parts by weight of hexabromocyclododecane as a halogen-based flame retardant and 100 parts by weight of a nucleating agent with respect to a total of 100 parts by weight of 95 parts by weight of polystyrene resin as raw material resin and 5 parts by weight of ethylene-vinyl acetate copolymer (EVA1) 0.5 parts by weight of talc, 0.3 parts by weight of barium stearate as a lubricant, and 0.5 parts by weight of bentonite as a water absorbing agent were dry blended.
The obtained mixture was transferred to a tandem type two-stage extruder in which a first extruder (single screw extruder having a diameter of 90 mm) and a second extruder (single screw extruder having a diameter of 65 mm) were connected in series at 40 to 60 kg / hr. Was supplied at a rate of
The resin mixture supplied to the first extruder is heated to about 200 ° C. and melt-kneaded, and 3 parts by weight of carbon dioxide, 1 part by weight of water and 3 parts by weight of dimethyl ether are used as a blowing agent with respect to 100 parts by weight of the raw resin. The resin was pressed into the resin near the tip of the first extruder. Then, while kneading in the second extruder connected to the first extruder, the resin temperature was cooled to 120 to 130 ° C., and then extruded and foamed into the atmosphere from the slit die provided at the tip of the second extruder. Thereafter, an extruded foam plate having a cross-sectional shape having a thickness of about 40 mm and a width of 150 mm is formed by a molding die placed in close contact with a slit die having a width of 50 mm adjusted to an interval of 1.5 mm and a molding roll placed downstream thereof. Obtained.
The evaluation of extrusion stability / formability was “◯”. The resulting extruded foam had a density of 28 kg / m ³ and an average cell diameter of 0.33 mm. The compressive strength was 32 N / cm ² , the thermal conductivity measured according to JIS A9511 was 0.035 W / mK, and the combustibility met the standards of JIS A9511.

(Example 2)
Extruded foam plates were obtained in the same manner as in Example 1, except that the raw resin was changed to 93 parts by weight of polystyrene resin and 7 parts by weight of ethylene-vinyl acetate copolymer (EVA1).
Table 1 shows the characteristics of the obtained foamed plate.

(Example 3)
Extruded foam plates were obtained in the same manner as in Example 1, except that the raw resin was changed to 95 parts by weight of polystyrene resin and 5 parts by weight of ethylene-vinyl acetate copolymer (EVA2).
Table 1 shows the characteristics of the obtained foamed plate.

Example 4
The foaming agent was changed to 3 parts by weight of carbon dioxide, 1 part by weight of water, 3 parts by weight of dimethyl ether, 0.25 parts by weight of isobutane and 0.75 parts by weight of normal butane. Extruded foamed plates were obtained by the same operation as in Example 1 except that the above was changed.
Table 1 shows the characteristics of the obtained foamed plate.

(Example 5)
The foaming agent was changed to 2 parts by weight of carbon dioxide, 0.5 parts by weight of water, 2.5 parts by weight of dimethyl ether, 0.5 parts by weight of isobutane and 1.5 parts by weight of normal butane. Extruded foamed plates were obtained in the same manner as in Example 1 except that the changes were made as shown in Table 1.
Table 1 shows the characteristics of the obtained foamed plate.

(Example 6)
Except for changing the blowing agent to 1 part by weight of carbon dioxide, 0.5 part by weight of water, 3 parts by weight of dimethyl ether, 0.5 part by weight of isobutane, and 1.5 parts by weight of normal butane, the same operation as in Example 1 was performed. An extruded foam board was obtained.
Table 1 shows the characteristics of the obtained foamed plate.

(Example 7)
Extrusion foaming was carried out in the same manner as in Example 1, except that the foaming agent was changed to 4 parts by weight of carbon dioxide and 1.2 parts by weight of water, and the types and amounts used of various compounding agents were changed as shown in Table 1. I got a plate.
Table 1 shows the characteristics of the obtained foamed plate.

(Example 8)
Extruded foam plates were obtained by the same operation as in Example 1 except that the flame retardant was changed to tetrabromobisphenol A-bis (2,3-dibromo-2-methylpropyl) ether.
Table 1 shows the characteristics of the obtained foamed plate.

(Comparative Example 1)
Extruded foamed plates were obtained by the same operation as in Example 1 except that the raw resin was changed to 100 parts by weight of polystyrene resin.
Table 1 shows the characteristics of the obtained foamed plate.

(Comparative Example 2)
Extruded foamed plates were obtained in the same manner as in Example 1, except that the blowing agent was changed to 4 parts by weight of carbon dioxide, 0.5 parts by weight of water, and 1 part by weight of dimethyl ether.
Table 1 shows the characteristics of the obtained foamed plate.

(Comparative Example 3)
Extruded foamed plates were obtained by the same operation as in Example 1 except that the foaming agent was changed to 5 parts by weight of carbon dioxide.
Table 1 shows the characteristics of the obtained foamed plate.
(Comparative Example 4)
Extruded foam plates were obtained in the same manner as in Example 1 except that the raw material resin was changed to 80 parts by weight of polystyrene resin and 20 parts by weight of ethylene-vinyl acetate copolymer (EVA1).
Table 1 shows the characteristics of the obtained foamed plate.

Claims (5)

A styrene resin extruded foam obtained by extrusion foaming a foamable molten resin composition obtained by melt-kneading a styrene resin mixture and a foaming agent,
The styrene resin mixture is a mixture of (A) 90 to 98 parts by weight of a styrene resin and (B) 2 to 10 parts by weight of an ethylene copolymer having a carbonyl group [total of (A) and (B) is 100 weights. Part],
And, as a foaming agent, it is characterized by using a foaming agent composed of carbon dioxide 10 mol% or more and less than 60 mol% and other physical foaming agents 90 mol% or less and more than 40 mol% with respect to the total amount of the foaming agent, Styrene resin extruded foam.   (B) The styrene resin extruded foam, wherein the ethylene copolymer having a carbonyl group is an ethylene-vinyl acetate copolymer.   The styrenic resin extrusion according to claim 1 or 2, wherein the other physical foaming agent is at least one selected from the group consisting of water, ether and saturated hydrocarbon having 3 to 5 carbon atoms. Foam. The styrene resin extruded foam according to claim 1, wherein the foam has a density of 33 kg / m ³ or less. A method for producing a styrene resin extruded foam obtained by extrusion foaming a foamable molten resin composition obtained by melt-kneading a styrene resin mixture and a foaming agent,
The styrene resin mixture is a mixture of (A) 90 to 98 parts by weight of a styrene resin and (B) 2 to 10 parts by weight of an ethylene copolymer having a carbonyl group [total of (A) and (B) is 100 weights. Part],
And as a foaming agent, the foaming agent which consists of carbon dioxide 10 mol% or more and less than 60 mol% and other physical foaming agents 9090 mol% or less and more than 40 mol% with respect to the total amount of foaming agents is used. The manufacturing method of a styrene resin extrusion foam.