JP5192188B2 - Method for producing styrene resin foam - Google Patents

Description

  The present invention relates to a styrene resin foam, for example, a styrene resin having excellent heat insulation performance and flame retardancy, which is used as a heat insulating material and a tatami core agent for walls, floors, roofs of buildings, etc. The present invention relates to a method for producing a foam.

  Since the styrenic resin foam has excellent heat insulating properties and suitable mechanical strength, it is widely used as a heat insulating material or the like that is molded into a plate having a constant width. Such a foam plate is generally a slit attached to the tip of an extruder, which is obtained by heating and melting a styrene resin material in an extruder and kneading a physical foaming agent into the melt. It is manufactured by extruding and foaming from a die having a shape or the like to a low pressure region, and molding (molding) by connecting a shaping device to a die outlet as desired.

Conventionally, chlorofluorocarbons (hereinafter referred to as CFC) such as dichlorodifluoromethane have been widely used as foaming agents used in the production of styrene resin extruded foams as described above. In recent years, hydrogen atom-containing fluorinated fluorinated hydrocarbons (hereinafter referred to as HCFC) having a small ozone depletion coefficient have been used instead of CFCs. However, since HCFC does not have an ozone depletion coefficient of 0 (zero), there is no danger of destroying the ozone layer. Therefore, it has been studied to use a fluorinated hydrocarbon (hereinafter referred to as HFC) having an ozone depletion coefficient of 0 (zero) and having no chlorine atom in the molecule as a foaming agent.
However, since this HFC has a large global warming potential, there is still room for improvement from the viewpoint of protecting the global environment. For this reason, a method for producing a polystyrene-based resin foam using an environment-friendly foaming agent having an ozone depletion coefficient of 0 (zero) and a low global warming potential has been studied.

  As a foaming agent, isobutane and isopentane have an ozone depletion coefficient of 0 (zero), a small global warming coefficient, and are preferable foaming agents from the viewpoint of the global environment. However, although isobutane and isopentane have lower thermal conductivity in the gas state than air, they have a higher thermal conductivity in the gas state than conventional chlorofluorocarbons such as CFC, HCFC, HFC, etc. When the same molar amount is used, it is impossible to obtain heat insulation equivalent to that of chlorofluorocarbons. Although it is possible to improve the heat insulation by increasing the content, isobutane and isopentane have been extremely difficult to impart flame retardancy to foams obtained with high flammability. In addition, isobutane and isopentane have a permeation rate with respect to the styrene resin that is extremely slower than that of air, but since the permeation rate is faster than that of CFC, they gradually dissipate from the foam. For this reason, the thermal conductivity of the foam also gradually increases. Therefore, it has been difficult to obtain a foam having both long-term heat insulation and flame retardancy using isobutane or isopentane as a foaming agent.

  The use of carbon dioxide or water, which has an ozone depletion coefficient of 0 (zero) and a lower global warming coefficient than hydrocarbons, as a foaming agent has been studied. The heat-insulating properties of the escaped foam are not satisfactory.

As a method for obtaining a thermoplastic resin foam having an excellent heat insulating property by using a foaming agent having an ozone depletion coefficient of 0 (zero), a method of adding a gas barrier resin to a polystyrene resin has been proposed (for example, Patent Document 1, Patent Document 2).
In Patent Document 1, a method of adding a nitrile resin as a gas barrier resin is used. In Patent Document 2, a vinyl alcohol resin is used as a gas barrier resin, and a compound having one or more hydroxyl groups in a molecule having a molecular weight of 1000 or less. A method of extrusion foaming in the presence of is reported. Gas barrier resin suppresses the escape of foaming agents with low thermal conductivity such as isobutane from the foam and improves the heat insulation immediately after extrusion by delaying the inflow of air into the foam cell. There is an effect to make. However, the gas barrier resin may hinder foaming, and it is difficult to produce a foam having a high expansion ratio. In addition, even if the dissipation from the foam such as isobutane is slow and the inflow rate of air into the cell is slow, the content of isobutane decreases after a long period of time and air flows into the cell. There are problems with maintaining long-term insulation.

  The present applicant uses a foaming agent having an ozone depletion coefficient of 0 (zero) and a small global warming coefficient, and is excellent in flame retardancy, has a low thermal conductivity over a long period of time and has a heat insulating property. As a method for producing a resin extruded foam, a method of adding graphite to a base resin was reported (Patent Document 3). The addition of graphite is effective in improving the heat insulation, but graphite acts as a bubble regulator and makes the texture of the bubbles finer. If a large amount of graphite is used to increase the heat insulation, the texture becomes too fine and it becomes difficult to form into a foamed plate, and the amount of addition is naturally limited, and the heat insulation of polystyrene resin foam is limited. Further studies were needed to fully improve it.

JP 2006-131719 A JP 2006-131757 A JP 2004-196907 A

  The object of the present invention is that the ozone depletion coefficient is 0 (zero), the global warming coefficient is small, the thermal conductivity is small, the heat insulation is excellent for a long period of time, and the flame retardancy is present under the circumstances as described above. The object is to provide a polystyrene resin extruded foam.

  As a result of various studies on the above problems, the present inventors have obtained a mixture of a styrene- (meth) acrylate copolymer and a styrene resin excluding the styrene- (meth) acrylate copolymer. Styrene-based so that the content of the (meth) acrylic acid ester component derived from the styrene- (meth) acrylic acid ester copolymer in the base resin made of the mixture is a specific amount. By using a mixture of a resin and the styrene- (meth) acrylic acid ester copolymer as a base resin, a styrene-based resin extruded with a flame retardant property having a low thermal conductivity and excellent heat insulation over a long period of time. The inventors have found that a foam can be obtained and have reached the present invention.

That is, the present invention
[1] A foamable molten resin composition obtained by kneading a styrene-based resin mixture and at least a foaming agent and a flame retardant is extruded and foamed to obtain a foam having an apparent density of 20 to 60 kg / m ³ and a thickness of 10 to 150 mm. In the manufacturing method, the styrenic resin mixture is composed of a mixture of a styrene- (meth) acrylic acid ester copolymer (A) and a styrenic resin (B), and the styrene- ( The (meth) acrylic acid ester component derived from the (meth) acrylic acid ester copolymer (A) is contained in an amount of 4 to 45% by weight based on the styrene-based resin mixture, and the styrene- (meth) acrylic acid ester copolymer The blend (A) is a styrene-methyl methacrylate copolymer, and the methacrylic acid methyl ester in the styrene-methyl methacrylate copolymer. It relates to a method for producing a styrene resin extruded foam, wherein Le component is 25 to 80 wt%.

[2] The styrene- (meth) acrylic acid ester copolymer (A) comprises a styrene-methyl methacrylate copolymer (C) having a methyl methacrylate component of 40 to 75% by weight and a methyl methacrylate component. The method for producing a styrene resin extruded foam according to the above [1], comprising 5% by weight or more and less than 40% by weight of a styrene-methyl methacrylate copolymer (D) ,

[3] The ratio of the styrene-methyl methacrylate copolymer (C) and the styrene-methyl methacrylate copolymer (D) is 90:10 to 50:50 in weight ratio. The method for producing a styrene resin extruded foam plate according to [2] ,

[4] The blowing agent is an aliphatic hydrocarbon having 3 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 6 carbon atoms, an aliphatic alcohol having 1 to 4 carbon atoms, or an alkyl chain having 1 to 3 carbon atoms. The method for producing an extruded foam of styrene resin according to any one of the above [1] to [3], which is at least one selected from dialkyl ethers of the above, alkyl chlorides having 1 to 3 carbon atoms, carbon dioxide and water. The gist.

According to the present invention, styrene- (meth) acrylic acid is used so that the (meth) acrylic acid ester component derived from the styrene- (meth) acrylic acid ester copolymer is 4 to 45% by weight as the foam base resin. The styrene resin mixture mixed with the ester copolymer is extruded and foamed using a foaming agent with zero ozone depletion coefficient such as hydrocarbon as the foaming agent, resulting in good foam moldability and low thermal conductivity. It is possible to obtain a styrene-based resin extruded foam that is suppressed and has flame retardancy with excellent heat insulation holding performance.
Since the extruded foam of the present invention has flame resistance excellent in heat insulation holding performance, it is useful as a heat insulating material for buildings.

  The base resin used in the production of the styrene resin foam of the present invention comprises a styrene resin mixture obtained by mixing a styrene resin with a styrene- (meth) acrylate copolymer as an essential component. That is, in the present invention, the styrene resin mixture is a mixture of a styrene- (meth) acrylic acid ester copolymer (A) and a styrene resin (B) as a base resin, and the styrene- ( The content of the (meth) acrylic acid ester component derived from the (meth) acrylic acid ester copolymer is 4 to 45% by weight. In this specification, acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid. Moreover, the styrene- (meth) acrylic acid ester copolymer in the present invention includes 10% to 90% by weight of a (meth) acrylic acid ester component in the copolymer.

  In the present invention, the content of the (meth) acrylic acid ester component derived from the styrene- (meth) acrylic acid ester copolymer (A) in the styrenic resin mixture as the base resin is 4 to 45% by weight, preferably In the styrene- (meth) acrylate copolymer so that it is 5 to 40% by weight, more preferably 8 to 38% by weight, still more preferably 10 to 35% by weight, and particularly preferably 12 to 25% by weight. In consideration of the content of the (meth) acrylic acid ester component, it is important to mix (A) and (B) by adjusting the mixing ratio within the above-mentioned range. In addition, the content of the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer and the content of the (meth) acrylic acid ester component in the styrene resin mixture are analyzed by pyrolysis gas chromatography. It can obtain | require by well-known methods, such as.

  When there are too few (meth) acrylic acid ester components in the said styrene-type resin mixture, the effect of reducing the heat conductivity of a foam will become small. On the other hand, when there are too many (meth) acrylic acid ester components, it is sufficient from the aspect of the thermal conductivity of the foam, but the flame retardancy deteriorates and satisfies the flame retardance standards required for building materials. Can not do. However, the flame retardancy is also affected by the type and amount of the flame retardant used for production, the density of the extruded foam, and the remaining amount of the foaming agent in the foam.

  The styrene- (meth) acrylic acid ester copolymer is a copolymer of styrene and (meth) acrylic acid lower alkyl ester. Specifically, for example, styrene-methyl acrylate copolymer, styrene- Examples include ethyl acrylate copolymer, styrene-propyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, and styrene-propyl methacrylate copolymer. Of these, a styrene-methyl acrylate copolymer and a styrene-methyl methacrylate copolymer, which have the intended intended effects, are preferred, and styrene-methyl methacrylate is more preferred. These styrene- (meth) acrylic acid ester copolymers can be used alone or in combination of two or more.

The styrenic resin (B) is a copolymer of a styrene homopolymer and a monomer copolymerizable with styrene, excluding the styrene- (meth) acrylate ester copolymer. Examples of such a copolymer include styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-poniphenylene ether copolymer, polystyrene and poniphenylene ether. , Styrene-acrylonitrile copolymer, acrylonitrile-styrene-butadiene copolymer, acrylonitrile-styrene acrylate copolymer, styrene-butadiene copolymer, styrene-methylstyrene copolymer, styrene-dimethylstyrene copolymer Styrene-ethylstyrene copolymer, styrene-diethylstyrene copolymer, high impact polystyrene (HIPS) and the like. The content of the styrene component in these styrenic copolymers is preferably 50% by weight or more, more preferably 80% by weight or more. These styrenic resins can be used alone or in combination of two or more.
Among the styrene resins, styrene homopolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene-methylstyrene copolymer Polymers are preferred, and styrene homopolymers and styrene-acrylic acid copolymers are particularly preferred.
In addition, in order to further improve the compatibility between the styrene resin and the styrene- (meth) acrylate copolymer, the styrene resin is copolymerized with several percent of a (meth) acrylate component. You can also.

  The styrene resin foam in the method of the present invention is a mixture of a styrene resin and a styrene- (meth) acrylic acid ester copolymer, and contains a predetermined amount of (meth) acrylic acid ester as an essential component. Styrene- (meth) acrylic such as polystyrene and styrene-methyl methacrylate copolymer is used for the excellent performance that the thermal conductivity is low and the heat insulating property is maintained for a long time by using the resin mixture as the base resin. The thermal conductivity and refractive index of the acid ester copolymer were examined.

For example, when comparing the thermal conductivity of polystyrene and styrene-methyl methacrylate copolymer with non-foamed material, styrene-methyl methacrylate copolymer has higher thermal conductivity than polystyrene. When a methyl methacrylate copolymer is mixed, the thermal conductivity is higher than that of polystyrene alone.
However, when comparing polystyrene single foam and styrene resin foam in which styrene-methyl methacrylate copolymer is mixed in polystyrene, styrene resin foam in which styrene-methyl methacrylate copolymer is mixed However, it has been found that the thermal conductivity decreases and the thermal conductivity decreases as the content of the methyl methacrylate component in the styrene resin foam increases.
The reason for this is not clear, but it is presumed that the absorption band of the methyl methacrylate component is further added to the absorption band of the infrared region of polystyrene, that is, the absorption band of the infrared region increases, and the mixed resin absorbs infrared rays. Is done. In general, in a non-foamed resin in a solid state, heat is transmitted through the solid mainly in the form of heat conduction. Therefore, the thermal conductivity of the non-foamed resin is determined by the thermal conductivity of the resin itself. On the other hand, in the foam, in addition to the heat conduction of the resin itself, heat is also transmitted by the gas in the foam bubbles (residual foaming agent + atmospheric components) and its convection, so that the foam foam film is multi-layered. Since it is formed, heat is also transmitted by infrared radiation between the bubble films. In the styrene resin foam in which styrene-methyl methacrylate copolymer is mixed with polystyrene, the effect of shielding this radiant heat transfer is improved, and it is assumed that the heat insulation is improved.
In addition, the said result is confirmed also about styrene- (meth) acrylic acid ester copolymers other than a styrene-methyl methacrylate copolymer.

  Furthermore, when a styrene-methyl methacrylate copolymer having a high content of the methyl methacrylate component in the styrene-methyl methacrylate copolymer is mixed, the effect of lowering the thermal conductivity is great. In a styrene resin foam mixed with a styrene-methyl methacrylate copolymer containing 5% by weight, the thermal conductivity is unique in the vicinity of the content of the methyl methacrylate component in the styrene resin foam being 40% by weight. It was recognized that there were small local minimum points. The range of this minimum point is influenced by the content of the methyl methacrylate component in the styrene-methyl methacrylate copolymer to be mixed, but the content of the methyl methacrylate component in the mixed resin is It is generally in the range of 30 to 50% by weight.

This is presumably due to the difference in compatibility and refractive index between polystyrene and styrene-methyl methacrylate copolymer.
When polystyrene and a styrene-methyl methacrylate copolymer are mixed, their refractive indexes are different (see Table (1) below), and the mixture is not completely compatible. This white turbidity diffuses the infrared rays, and the shielding effect of radiant heat transfer is improved to reduce the thermal conductivity, so that it is presumed that the heat insulation is improved only when the foam is used. Furthermore, a copolymer having a high content of the methyl methacrylate component in the styrene-methyl methacrylate copolymer has a large difference in refractive index from polystyrene compared to a copolymer having a low content of the methyl methacrylate component (see below). Table (1)), the mixture with polystyrene becomes more cloudy. As a result, it is surmised that the shielding effect is further improved and the thermal conductivity of the foam is further reduced. At this time, since the styrene-methyl methacrylate copolymer has styrene as a copolymerization component, the compatibility with polystyrene is not so bad as to greatly affect foaming. A good foam can be obtained.

（ＰＳ：ポリスチレン、ＭＳ：スチレン−メタクリル酸メチル共重合体、Ｍ成分：メタクリル酸メチル成分を示す。） (Table 1)

(PS: polystyrene, MS: styrene-methyl methacrylate copolymer, M component: methyl methacrylate component)

In addition, although different from the intended purpose, the styrene resin foam produced by the method of the present invention exhibits excellent heat insulation properties because the styrene- (meth) acrylate copolymer in the styrene resin mixture is slightly However, it is thought that having gas barrier properties also contributes. Immediately after the production of the foam, the gas barrier property can slightly delay the dissipation of the residual foaming agent contained in the foam into the atmosphere and the inflow of atmospheric components from the atmosphere into the foam bubbles. Therefore, it is speculated that there is an effect of further reducing the thermal conductivity of the foam due to a synergistic effect with the above-described radiation heat transfer shielding effect.
On the other hand, when a long time has passed after the foam production, the atmospheric component has a high gas permeation rate, so the inflow of the atmospheric component into the bubbles of the foam is completed, and the partial pressure of the atmospheric component in the bubbles is styrene- (meta ) It will be the same value regardless of the presence or absence of acrylic ester copolymer, but since the dissipation of the foaming agent from the foam can be slightly suppressed, the concentration of the remaining foaming agent in the bubbles is increased. It is speculated that a low thermal conductivity can be achieved by a synergistic effect with the radiation heat transfer shielding effect described above.

  In the present invention, the resin mixture of a styrene resin and a styrene- (meth) acrylic acid ester copolymer, which is a base resin for a foam, is a styrene- (meth) acrylic acid ester copolymer (A) 10-80. It is preferable to mix in the range of 20% by weight and 20% to 90% by weight of styrene resin (B) ((A) + (B) = 100% by weight), and (A) is 10 to 70% by weight and (B) Is more preferably mixed in the range of 30 to 90% by weight ((A) + (B) = 100% by weight), (A) being 10 to 60% by weight and (B) being 40 to 90% by weight ( (A) + (B) = 100% by weight) is more preferable. In addition, when (A) is a plurality of two or more types, and (B) is a plurality of two or more types, the total thereof is 100% by weight. From the above examination results, etc., if the content of the (meth) acrylic acid ester component derived from the styrene- (meth) acrylic acid ester copolymer in the resin mixture is excessive, the flame retardancy will be affected. (Meth) acrylic derived from the styrene- (meth) acrylic acid ester copolymer in the resin mixture in consideration of the content of the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer It is necessary to adjust the content of the acid ester component to the specific range described above, that is, to be 4 to 45% by weight, and to mix with the styrenic resin.

In the present invention, the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer is preferably 25 to 80% by weight, more preferably 30 to 75% by weight, More preferably, it is 75 weight%, and it is especially preferable that it is 45-75 weight%. If the amount of the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer is too large, the copolymer is difficult to be mixed with the styrene resin, so that foamability is reduced and a good foam is obtained. May not be obtained, and the thermal decomposition temperature of the copolymer is lowered, so that a foam having desired flame retardancy may not be obtained.
That is, when the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer is within the above range, as described above, when the copolymer is mixed with a styrene resin, foaming occurs. Since the white turbidity occurs due to the difference in refractive index between the copolymer and the styrenic resin without significantly impairing the properties, the effect of reducing the thermal conductivity of the resulting foam is further increased, and the desired It becomes easy to obtain a foam having flame retardancy.
In addition, the styrene- (meth) acrylic acid ester copolymer may be used in combination of two or more types having different (meth) acrylic acid ester component content, but two or more types of styrene- (meth) acrylic are used. When the acid ester copolymer is used in combination, the average value obtained from the content of the (meth) acrylic acid ester component in each styrene- (meth) acrylic acid ester copolymer is the styrene- (meth) acrylic acid ester. The amount of the (meth) acrylic acid ester component of the copolymer (A) is used.

As described above, the styrene- (meth) acrylic acid ester copolymer is not so badly compatible with the styrene resin as to inhibit foaming, but in the styrene- (meth) acrylic acid ester copolymer. As the content of the (meth) acrylic acid ester component increases, the compatibility with the styrenic resin slightly decreases. When a styrene- (meth) acrylic acid ester copolymer having a high amount of (meth) acrylic acid ester component is mixed with a styrenic resin, the effect of reducing the thermal conductivity of the resulting foam is high, but the resulting foam is There is a risk of becoming slightly brittle.
Therefore, when the styrene- (meth) acrylic acid ester copolymer (C) having a (meth) acrylic acid ester component of 40 to 75% by weight is used, the (meth) acrylic acid ester component is 5% by weight or more. It is preferable to use a styrene- (meth) acrylic acid ester copolymer (D) that is less than 40% by weight in combination. When the (meth) acrylic acid ester component of the styrene- (meth) acrylic acid ester copolymer (D) is within the above range, the styrene- (meth) acrylic acid ester copolymer (D) Since the compatibility with both of the styrene- (meth) acrylic acid ester copolymer (C) is more excellent, the thermal conductivity can be reduced and the brittleness can be improved with almost no decrease in rigidity. Therefore, it is preferable. From this viewpoint, the (meth) acrylic acid ester component in the styrene- (meth) acrylic acid ester copolymer (D) is more preferably 5 to 35% by weight, and more preferably 10 to 30% by weight. It is preferably 15 to 25% by weight, particularly preferably. In addition, a styrene- (meth) acrylic acid ester copolymer (D) can be used 1 type or in mixture of 2 or more types. In addition, the styrene- (meth) acrylic acid ester copolymers (C) and (D) are preferably styrene-methyl acrylate copolymers and styrene-methyl methacrylate copolymers for the reasons described above. An acid methyl copolymer is more preferred.

Furthermore, when using the said styrene- (meth) acrylic acid ester copolymer (C) and a styrene- (meth) acrylic acid ester copolymer (D) together, a styrene- (meth) acrylic acid ester copolymer (A ) If the ratio of the styrene- (meth) acrylic acid ester copolymer (D) is 10% by weight or more, the compatibility between the styrene resin and the styrene- (meth) acrylic acid ester copolymer (C) Since an improvement effect becomes high, since the brittleness improvement effect of a foam becomes higher, it is preferable. From this viewpoint, the ratio of the styrene- (meth) acrylic ester copolymer (D) in the styrene- (meth) acrylic ester copolymer (A) is more preferably 20% by weight or more, and more preferably 30% by weight or more. Further preferred.
On the other hand, when the ratio of the styrene- (meth) acrylic acid ester copolymer (C) in the styrene- (meth) acrylic acid ester copolymer (A) is 50% by weight or more, the heat conduction of the resulting foam is obtained. In order to adjust the (meth) acrylic acid ester component in the styrene resin mixture to a desired concentration while maintaining the effect of reducing the rate, a styrene- (meth) acrylic acid ester copolymer in the styrene resin mixture Since the ratio which mixes (A) can be decreased, since the brittle improvement effect of the obtained foam becomes still higher, it is preferable. From this viewpoint, the ratio of the styrene- (meth) acrylic acid ester copolymer (C) in the styrene- (meth) acrylic acid ester copolymer (A) is more preferably 55% by weight or more, and 60% by weight. % Or more is more preferable.

In the styrene resin mixture of the present invention, other polymers can be mixed within a range that does not impair the object and effects of the present invention. Other polymers include polyethylene resins, polypropylene resins, styrene-butadiene-styrene block copolymers, and hydrogenated products thereof, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof, styrene-ethylene. Examples thereof include copolymers, acrylonitrile-alkyl acrylate-butadiene copolymers, and polymethyl methacrylate.
The blending amount of these other polymers is preferably 30 parts by weight or less, and more preferably 10 parts by weight or less, based on 100 parts by weight of the styrene resin mixture.

  In the present invention, a conventionally known foaming agent having an ozone depletion coefficient of zero can be used. In consideration of long-term heat insulation, a foaming agent having a relatively slow gas permeability to a base resin composed of the styrene resin mixture of the present invention as shown below is preferable. Examples of the blowing agent having a relatively slow gas permeability include aliphatic hydrocarbons having 3 to 5 carbon atoms, specifically, propane, normal butane, isobutane, normal pentane, isopentane, neopentane, and the like. 6 alicyclic hydrocarbons, specifically, cyclobutane, cyclopentane, cyclohexane and the like. Among these, in order to have a slow gas permeability and excellent foamability, normal butane, isobutane, normal pentane, isopentane, and cyclopentane are more preferable. Isobutane is preferred. These foaming agents can be used alone or in combination of two or more.

  Furthermore, in consideration of the flame retardancy of the foam obtained, the amount of the aliphatic hydrocarbon as described above is limited, so the base material comprising the aliphatic hydrocarbon and the styrene resin mixture of the present invention It is preferable to use a mixed foaming agent used in combination with a foaming agent having a gas permeability to the resin that is faster than that of the aliphatic hydrocarbon. By using the mixed foaming agent, the amount of the aliphatic hydrocarbon added can be reduced, and most of the foaming agent other than the aliphatic hydrocarbon is dissipated from the foam immediately after foaming. The desired flame retardancy can be achieved by adding.

  Examples of the foaming agent having a high gas permeability include alkyl chlorides, alcohols, ethers, ketones, carbon dioxide, and water. Among these blowing agents, alkyl chlorides having 1 to 3 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, ethers having 1 to 3 carbon atoms in the alkyl chain, carbon dioxide, water, and the like are preferable. Specifically, examples of the alkyl chloride having 1 to 3 carbon atoms include methyl chloride and ethyl chloride. Examples of the aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, propyl alcohol, isopropyl alcohol, butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, aryl alcohol, crotyl alcohol, propargyl alcohol and the like. . Examples of ethers having 1 to 3 carbon atoms in the alkyl chain include dimethyl ether, ethyl methyl ether, diethyl ether, and methylene dimethyl ether. In particular, methyl chloride, dimethyl ether, carbon dioxide, and water are particularly preferable among the foaming agents because of their high gas permeability and excellent handleability. These foaming agents can be used alone or in combination of two or more.

  Furthermore, HFC such as 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and the like can be added to the foaming agent within a range that does not impair the intended purpose of the present invention.

The amount of these foaming agents is appropriately selected in relation to the desired foaming ratio, and in order to obtain a foam having an apparent density of 20 to 60 kg / cm ³ , usually 0.5 to 3 as a mixed foaming agent per 1 kg of styrenic resin. Mole is added, and preferably 0.6 to 2.5 mol is added.

  Since the styrenic resin foam obtained by the present invention is mainly used as a heat insulating plate for construction, an extruded polystyrene foam described in “Measurement method A” as defined in JIS A9511 (2006) 5.13.1. A high level of flame retardancy that satisfies the flammability standards for heat insulation plates is required. Furthermore, the styrenic resin foam obtained by the present invention is required to satisfy the standard of thermal conductivity defined by JIS A9511 (2006) 4.2. Therefore, the addition amount of the aliphatic hydrocarbon in the present invention needs to be added so that the flame retardancy and the standard of thermal conductivity are compatible so as to contain the hydrocarbon in the foam. There is. Furthermore, the addition amount of the aliphatic hydrocarbon is appropriately determined according to the required standard of thermal conductivity. Accordingly, the foaming agent having a relatively fast gas permeability as described above is appropriately determined according to the amount of the aliphatic hydrocarbon in order to achieve a desired apparent density.

  A styrenic resin that requires high thermal insulation performance that satisfies the flammability standard for the extruded polystyrene foam heat insulating plate described in “Measurement Method A” as defined in JIS A9511 (2006) 5.11, 1 The resin foam is achieved by adding a flame retardant in addition to the adjustment of the hydrocarbon content. As the flame retardant used here, a flame retardant conventionally used in the production of a styrene resin foam can be used.

  A brominated flame retardant is preferably used as the flame retardant. Examples of brominated flame retardants include tetrabromobisphenol A, tetrabromobisphenol A bis (2,3-dibromopropyl ether), tetrabromobisphenol A bis (2-bromoethyl ether), tetrabromobisphenol A bis (allyl ether). ), 2,2-bis [4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane, tetrabromobisphenol S, tetrabromobisphenol S-bis (2,3-dibromopropyl) Ether), hexabromocyclododecane, tetrabromocyclooctane, tris (2,3-dibromopropyl) isocyanurate, tribromophenol, decabromodiphenyl oxide, tris (tribromoneopentyl) phosphate, brominated bisphenol Such as over ether derivatives, and the like. These compounds can be used alone or in admixture of two or more. Among the above brominated flame retardants, the thermal stability is high and a high flame retardant effect is obtained. Therefore, hexabromocyclododecane, tetrabromobisphenol A bis (2,3-dibromopropyl ether), 2,2- Bis [4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane and tris (2,3-dibromopropyl) isocyanurate are particularly preferred.

  The content of the flame retardant in the extruded foam plate of the present invention is 1 per 100 parts by weight of the polystyrene-based resin in order to improve the flame retardancy and minimize the decrease in foamability and mechanical properties. 10 to 10 parts by weight is preferred, 1.5 to 7 parts by weight is more preferred, and 2 to 5 parts by weight is even more preferred.

  Furthermore, in the present invention, a flame retardant aid can be used in combination with the brominated flame retardant for the purpose of further improving the flame retardancy of the extruded foam plate. Examples of the flame retardant aid include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4 -Diphenylalkanes such as diethyl-3,4-diphenylhexane, 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-ethyl-1-pentene, diphenylalkene, triphenyl phosphate, cresyldi Nitrogen-containing cyclic compounds such as 2,6-xylenyl phosphate, antimony trioxide, diantimony pentoxide, ammonium sulfate, zinc stannate, cyanuric acid, isocyanuric acid, triallyl isocyanurate, melamine cyanurate, melamine, melam, melem , Silicone compounds, boron oxide, zinc borate, zinc sulfide, etc. , Red phosphorus-based, ammonium polyphosphate, phosphorus-based compounds such as phosphazene and the like. These compounds can be used alone or in admixture of two or more.

  As a method of blending the above flame retardant into the styrene resin mixture, a predetermined ratio of the flame retardant is supplied together with the styrene resin to the raw material supply section provided in the upstream portion of the extruder, and the styrene resin is fed into the extruder. A method of kneading with the mixture can be employed. In addition, a flame retardant can also be supplied into the molten styrene resin mixture from a flame retardant supplier provided in the extruder.

  When supplying a flame retardant to an extruder, a method of supplying a dry blend of a flame retardant and a styrene resin mixture to the extruder, a melt-kneaded material obtained by kneading a flame retardant and a styrene resin with a kneader or the like A method of supplying to an extruder, a method of supplying a liquid flame retardant heated and melted in advance into the extruder, or a method of preparing a flame retardant master batch and supplying it to the extruder can be employed. In particular, it is preferable to adopt a method of preparing a flame retardant master batch and supplying it to an extruder from the viewpoint of dispersibility.

  The styrenic resin foam in the present invention is subjected to a combustion standard combustibility measurement for a polystyrene foam heat insulating plate defined in JIS A9511 (2006) 5.13.1 “Measurement method A”. The flame disappears within 3 seconds, there is no residual dust, and it does not burn beyond the combustion limit indicator line. Therefore, the plate-like foam having such combustion characteristics can suppress the spread of fire even when ignited, and has the safety required as an extruded polystyrene foam heat insulating plate for building materials. .

  The styrene resin foam in the present invention has a thickness of 10 to 150 mm. When the thickness is less than 10 mm, the heat insulating property required for the heat insulating material is insufficient. On the other hand, when it exceeds 150 mm, the handleability as a heat insulating material worsens. Therefore, the thickness is preferably 15 mm to 120 mm.

The apparent density of the styrenic resin foam of the present invention is 20 to 60 kg / cm ³ . It is quite difficult to produce a low density extruded foam having an apparent density of less than 20 kg / cm ³ , and even if such a low density extruded foam is obtained, it is a machine to be used as a heat insulating material. The mechanical strength is insufficient. On the other hand, when the apparent density is too large, it is difficult to exhibit sufficient heat insulation unless the thickness of the extruded foam is made larger than necessary, and it is not preferable from the viewpoint of light weight.

In the method of the present invention, the apparent density of the foam is 20 to 60 kg / cm ³ , preferably 22 to 55 kg / cm ³ , and high insulation performance can be obtained. When a flame retardant used for a foam, such as hexabromocyclododecane, is used, there is an advantage that a high flame retardant performance can be imparted with a relatively small amount of the flame retardant.

  The thickness direction average cell diameter of the extruded foam obtained by the present invention is preferably 0.05 to 2 mm, more preferably 0.06 to 1 mm, and further preferably 0.07 to 0.8 mm. When the average cell diameter is within this range, an extruded foam plate having excellent mechanical strength and higher heat insulation can be obtained. If the bubble diameter is too small, it will be difficult to obtain an extruded foam with a large thickness and low apparent density, and the foam film will be too thin to easily transmit infrared rays, resulting in poor insulation of the foam. There is a risk of doing. On the other hand, if it is too large, an extruded foam having the desired heat insulating property cannot be obtained.

The measurement method of the average bubble diameter in this specification is as follows. The average cell diameter (D _T : mm) in the thickness direction of the extruded foam and the average cell diameter (D _W : mm) in the width direction of the extruded foam are perpendicular to the widthwise vertical cross section of the extruded foam (the direction of extrusion of the extruded foam plate). The average cell diameter (D _L : mm) in the longitudinal direction of the extruded foam was bisected at the longitudinal section of the extruded foam plate (parallel to the extrusion direction of the extruded foam and at the center in the width direction). Project a magnified image (vertical section) onto a screen or monitor using a microscope, draw a straight line in the direction to be measured on the projected image, count the number of bubbles intersecting the straight line, and calculate the length of the straight line (however, , This length is not the length of the straight line on the enlarged projected image, but the length of the true straight line considering the magnification of the projected image)) divided by the number of counted bubbles, respectively. The average bubble diameter in the direction is determined.

The measurement method of the average bubble diameter will be described in detail. The measurement of the average bubble diameter in the thickness direction (D _T : mm) is performed by measuring a straight line extending over the entire thickness in the thickness direction at a total of three locations at the center and both ends of the vertical cross section in the width direction. From the length of each straight line and the number of bubbles intersecting the straight line, the average diameter of the bubbles existing on each straight line (the length of the straight line / the number of bubbles intersecting the straight line) is obtained, and Let the arithmetic mean value of an average diameter be the average bubble diameter ( _DT : mm) of the thickness direction.

The average bubble diameter (D _W : mm) in the width direction is a width of a straight line having a length of 3 mm at a position that bisects a total of three extruded foams at the center and both ends in the width direction. From the straight line of 3 mm length and (number of bubbles crossing the straight line minus 1), the average diameter of bubbles existing on each straight line (3 mm / (number of bubbles crossing the straight line minus 1)) The arithmetic average value of the obtained average diameters at the three locations is taken as the average cell diameter in the width direction (D _W : mm).

The average cell diameter in the longitudinal direction (D _L : mm) was determined by dividing the extruded foam into two equal parts in the thickness direction at a total of 3 locations in the center and both ends of the longitudinal cross section obtained by cutting the test piece. A straight line having a length of 3 mm is drawn in the longitudinal direction at a position where the average diameter of bubbles existing on each straight line from the straight line having a length of 3 mm and (the number of bubbles crossing the straight line −1) (3 mm / (the straight line) The number of bubbles intersecting -1)) is obtained, and the arithmetic average value of the obtained average diameters at the three locations is defined as the average bubble diameter in the longitudinal direction (D _L : mm). The average cell diameter in the horizontal direction of the extruded foam plate _(D H: mm) is the arithmetic mean value of _{D W} and _{D L.}

Furthermore, in the extruded foam obtained by the present invention, the cell deformation rate is preferably 0.7 to 2.0. The bubble deformation rate refers to a value (D _T / D _H ) calculated by dividing _DT obtained by the above measurement method by _DH , and the bubble deformation rate is flatter as the bubble deformation rate is smaller than 1. The larger the value is, the longer the image is. If the bubble deformation ratio is less than 0.7, the compression strength may be reduced because the bubbles are flat, and the flat bubbles are more likely to return to a spherical shape, so the dimensional stability of the extruded foam also decreases. There is a fear. If the bubble deformation rate exceeds 2.0, the number of bubbles in the thickness direction decreases, and there is a possibility that the desired high heat insulation property cannot be obtained. From such a viewpoint, the bubble deformation rate is preferably 0.8 to 1.5, and more preferably 0.8 to 1.2. When the bubble deformation rate is within the above range, an extruded foam having excellent mechanical strength and high heat insulating properties can be obtained.

  The closed cell ratio of the plate-like extruded foam according to the present invention is preferably 90% or more, and more preferably 93% or more. The higher the closed cell ratio, the higher the heat insulation performance can be maintained. The closed cell ratio is expressed by the following formula (1) using the true volume Vx of the extruded foam measured using an air comparison type hydrometer 930 type manufactured by Toshiba Beckman Co., Ltd. according to the procedure C of ASTM-D2856-70. ) To calculate the closed cell ratio S (%).

  As the sample, cut samples were cut out from three different portions in the extruded foam and measured for each cut sample. The cut sample is a sample that has been cut from the extruded foam into a size of 25 mm × 25 mm × 20 mm and does not have a molded skin. When the thickness is small and a 20 mm sample cannot be cut out in the thickness direction, for example, two samples (cut samples) cut into a size of 25 mm × 25 mm × 10 mm are stacked and measured.

(Equation 1)
S (%) = (Vx−W / ρ) × 100 / (VA−W / ρ) (1)
However, Vx: the true volume (cm ³ ) of the cut sample used for the above measurement (the sum of the volume of the resin constituting the cut sample of the extruded foam and the total volume of bubbles in the closed cell portion in the cut sample) Equivalent to.)
VA: apparent volume (cm ³ ) of the cut sample calculated from the outer dimensions of the cut sample used for measurement
W: Total weight of cut sample used for measurement (g)
ρ: Density of resin constituting the extruded foam (g / cm ³ )

  In the method according to the present invention, if desired, the heat insulating property can be further improved by adding a heat insulating property improving agent. Examples of the heat insulation improver include fine powders such as metals, metal oxides, ceramics, carbon black and graphite, infrared shielding pigments, hydrotalcite and the like. These can be used singly or in combination of two or more. However, since the heat-insulating agent for fine powders such as metals, metal oxides, carbon black, and graphite has a bubble-adjusting action, a large amount of addition makes the bubble diameter fine. Therefore, the molding becomes difficult, and problems such as incombustibility and deterioration of mechanical properties occur, which is not preferable. The amount of the heat insulation improver added is 0.5 parts by weight based on 100 parts by weight of the styrene resin mixture. -5 parts by weight, preferably 1-4 parts by weight.

  In the production of the styrene resin foam according to the present invention, the method of blending the heat insulation improver into the styrene resin mixture is a method of dry blending a predetermined amount of the heat insulation improver with the styrene resin mixture and blending the blend. The product can be supplied to the extruder from a supply unit provided upstream of the extruder, kneaded and blended into the molten styrene resin mixture. Also, a master batch in which the heat-insulating agent having a high concentration is previously blended with a polystyrene resin is prepared, and this is supplied to an extruder and melted and kneaded with a styrene-based resin mixture not containing the heat-insulating agent. It can be a molten styrene resin mixture. In particular, it is preferable to adopt a master batch method from the viewpoint of dispersibility. Preparation of the master batch of the heat insulation improver is adjusted so that the heat insulation improver is contained in the styrene resin in an amount of 10 to 80% by weight, preferably 20 to 70% by weight, and further 30 to 60% by weight. It is preferable.

  In addition, various additives such as air conditioners, colorants such as pigments and dyes, heat stabilizers, and other fillers can be appropriately added to the styrenic resin in the present invention as necessary.

  Examples of the air conditioner include conventionally known chemical foams such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, aluminum oxide, clay, bentonite, diatomaceous earth and the like, and azodicarbodiamide. An agent or the like can be used. Among these, talc is preferable because it is easy to adjust the bubble diameter and easily adjust the bubble diameter without impairing the flame retardancy. In particular, fine talc having a particle size of 50% by light transmission centrifugal sedimentation and a size of 0.1 to 20 μm is preferable, and a particle size of 0.5 to 15 μm is preferable. The addition amount of the cell regulator varies depending on the type of the regulator, the target cell diameter, and the like. ), Preferably 7 parts by weight or less (including 0), more preferably 5 parts by weight or less (including 0), and particularly preferably 0.01 to 4% by weight.

  From the viewpoint of dispersibility, it is preferable to prepare and use a cell batch of a styrene resin master batch. Preparation of the master batch of the foam preparation agent is preferably prepared such that the content of talc is 20 to 80% by weight with respect to the styrenic resin when talc is used as the foam regulator, for example, 30 It is more preferable to adjust so that it may become -70weight%.

  The styrenic resin foam of the present invention is obtained by press-fitting a required amount of foaming agent from a predetermined position of an extruder into a melt obtained by melting and kneading a styrene resin, a flame retardant, and other additives in an extruder. A styrene resin foamable melt composition containing a kneaded foaming agent, flame retardant, etc. is extruded from the die lip at the tip of the extruder under atmospheric pressure, and then shaped into a predetermined shape (plate shape) by a shaping device (guider) Manufactured by molding. For the shaping device, for example, a shaping tool composed of a pair of upper and lower polytetrafluoroethylene plates is used.

The styrene resin extruded foam according to the present invention uses a styrene- (meth) acrylate copolymer as a constituent component of the styrene resin mixture, and the (meth) acrylate component derived from the copolymer is the above-mentioned component. Since the styrene-based resin mixture contained in the above range is used as the base resin, dissipation of the foaming agent from the foam can be suppressed.
The residual amount of foaming agent in the foam was measured using a gas chromatograph. Specifically, a test piece without a molded skin of 200 mm × 200 mm × 25 mm cut out from the extruded foam immediately after the foam production was stored in an atmosphere of 23 ° C. and 50% humidity. 100 days after the production, the width of the test piece was 2.5 cm, and the sample was cut into a length such that the weight of the sample was 1 g. Put this sample in a sample bottle with a lid containing toluene, close the lid, then stir well and perform a gas chromatographic analysis using a solution in which the foaming agent in the foam is dissolved in toluene. Asked.

Measurement conditions for gas chromatographic analysis Column: Shinwa Kogyo Co., Ltd. Carrier: chromosorb W, 60-80 mesh, AW-DMCS treated product Liquid phase: Silicone DC550 (liquid phase amount 20%)
Column dimensions: Column length 4.1m, column inner diameter 3.2mm
Column material: Glass column temperature: 40 ° C
Inlet temperature: 200 ° C
Carrier gas: nitrogen carrier gas speed: 50 ml / min.
Detector: FID
Detector temperature: 200 ° C
Quantification: Internal standard method

  Hereinafter, the present invention will be described in detail together with comparative examples by way of examples.

＊１） ＪＩＳ Ｋ７２１０（１９９９）の試験方法Ａにより測定されるメルトマスフローレイトを意味し、試験温度２００℃、荷重５ｋｇで測定された値である。
＊２）：２００℃、せん断速度１００／ｓでの測定値 [material]
The raw materials used are shown below.
(Table 2)
Styrenic resin

* 1) This means a melt mass flow rate measured by JIS K7210 (1999) test method A, which is a value measured at a test temperature of 200 ° C. and a load of 5 kg.
* 2): Measured value at 200 ° C and shear rate 100 / s

＊１）：スチレン−（メタ）アクリル酸エステル共重合体中の（メタ）アクリル酸エステル成分含有量
＊２）：２００℃、せん断速度１００／ｓでの測定値 (Table 3)
Styrene- (meth) acrylic acid ester copolymer

* 1): Content of (meth) acrylic acid ester component in styrene- (meth) acrylic acid ester copolymer * 2): Measured value at 200 ° C. and shear rate of 100 / s

[Production example of resin I]
In an autoclave with an internal volume of 50 L with a stirrer, 18 kg of deionized water, 21 g of tricalcium phosphate (made by Taihei Chemical Sangyo Co., Ltd.) as a suspending agent, disodium dodecyl diphenyl ether sulfonate as a surfactant (Perex made by Kao Corporation) SSH 50% aqueous solution) 14 g and sodium acetate 27 g as an electrolyte were added. Then, 18 g of t-butylperoxy-2-ethylhexanoate (Nippon Yushi Co., Ltd., Perbutyl O) and 18 g of t-butyl peroxy-2-ethylhexyl monocarbonate (Nippon Yushi Co., Ltd., Perbutyl E) as an initiator, As a chain transfer agent, 46 g of α-methylstyrene dimer (NOFMER MSD manufactured by NOF Corporation) was dissolved in 8.5 kg of methyl methacrylate and 5.7 kg of styrene monomer and charged into the autoclave while stirring at 230 rpm. After the atmosphere in the autoclave was replaced with nitrogen, the temperature was raised and the temperature was raised to 90 ° C. over 1 hour and a half. After reaching 90 ° C., the temperature was maintained at 90 ° C. for 5 hours, and the temperature was further increased to 120 ° C. over 2 hours, and then maintained at 120 ° C. for 4 hours. Then, it cooled to 30 degreeC in about 3 hours. During the temperature increase, when reaching 60 ° C., 42 g of a 0.1% aqueous solution of potassium persulfate was added as a suspension aid. After cooling, the contents are taken out from the autoclave, dehydrated with a centrifugal separator, water adhering to the surface is removed with a fluid dryer, and a methyl methacrylate-styrene copolymer having a methyl methacrylate content of 60% by weight is removed. Got.

[Measuring method of melt viscosity]
The melt viscosities of the resins in Tables 2 and 3 were measured under the following conditions using a Capillograph Model 1D manufactured by Toyo Seiki Seisakusho. A capillary with a hole diameter of 1.0 mm and a length of 10 mm is attached to the tip of a barrel diameter of 9.55 mm (effective length of 250 mm), and the raw material is filled in a furnace heated to 200 ° C., and preheating for 4 minutes is sufficient. And then extruded with a piston so that the shear rate of the capillary part becomes 100 / s, and the melt viscosity was measured after the extrusion load was stabilized. In addition, the filling amount of the raw material is sufficient to ensure 15 cc or more after melting and defoaming. As a defoaming method, bubbles are sufficiently removed by temporarily applying a load to the piston during preheating of the raw material. did.

(Table 4)
(Meth) acrylic acid ester polymer

  Air bubble regulator: A talc masterbatch comprising 35% by weight of polystyrene, 60% by weight of talc (High Filler # 12 manufactured by Matsumura Sangyo Co., Ltd.) and 5% by weight of a dispersant was used.

Flame retardant A: A flame retardant masterbatch containing 93% by weight of hexabromocyclododecane was used.
Flame retardant B: A flame retardant masterbatch containing 93% by weight of 2,2-bis [4- (2,3-dibromo-2-methylpropoxy) -3,5-dibromophenyl] propane was used.

Examples 1-15, 17-34, Comparative Examples 1-10, 12-16
A first extruder with an inner diameter of 65 mm, a second extruder with an inner diameter of 90 mm, and a third extruder with an inner diameter of 150 mm are connected in series, and a blowing agent inlet is provided near the end of the first extruder, A production apparatus in which a flat die having a resin discharge port (die lip) having a rectangular cross section of 1 mm × width 90 mm was connected to the outlet of the third extruder was used.
At the resin outlet of the third extruder, a shaping device (guider) composed of a plate made of a pair of upper and lower polytetrafluoroethylene resins installed in parallel with this is attached.
A resin, a flame retardant and a bubble regulator are supplied to the first extruder so as to have the blending amounts shown in Tables 5-9 and 11-15, heated to 220 ° C., and melted and kneaded. The required amount of the foaming agent having the composition shown in Tables 5 to 9 and 11 to 15 is supplied to the melt from the foaming agent injection port provided near the tip of the extruder, followed by the foamable molten resin composition melt-kneaded. The foaming temperature as shown in the table by supplying the resin temperature to the second extruder and the third extruder (in the table, expressed as the foaming temperature. This foaming temperature is measured at the position of the junction between the extruder and the die. The temperature of the foamable molten resin composition), and then extruded from the die lip into the guider at a discharge rate of 50 kg / hr and foamed while being foamed and arranged in parallel with a gap of 28 mm in the thickness direction of the extruded foam. Formed into a plate by passing through the inside (shaped) It was produced plate-like styrene resin extruded foam by.
In addition, the blending ratio of the styrene resin and the styrene- (meth) acrylic acid ester copolymer in Tables 5 to 15 is a ratio with respect to 100% by weight of the styrene resin mixture. For example, in Example 11 in Table 7 When PS1 / PS2 is 10/50 and resin A is 40, PS1 is 10% by weight, PS2 is 50% by weight, and resin A is 40% by weight.

Example 16 and Comparative Example 11
A first extruder with an inner diameter of 150 mm and a second extruder with an inner diameter of 200 mm are connected in series, a blowing agent injection port is provided near the end of the first extruder, and a cross section with a gap of 1 mm × width of 440 mm A production apparatus in which a flat die having a rectangular resin discharge port (die lip) was connected to the outlet of the second extruder was used.
At the resin outlet of the second extruder, a shaping device (guider) composed of a plate made of a pair of upper and lower polytetrafluoroethylene resins installed in parallel with the resin outlet is attached.
Resin, flame retardant, and bubble conditioner are supplied to the first extruder so as to have the blending amounts shown in Table 10, heated to 220 ° C., melted and kneaded, and near the tip of the first extruder. The required amount of the foaming agent having the blending composition shown in the table is supplied to the melt from the provided foaming agent inlet, and the foamable molten resin composition melt-kneaded is supplied to the second extruder, and the resin temperature is tabulated. After adjusting to a suitable foaming temperature (shown as foaming temperature in the table. This foaming temperature is the temperature of the foamable molten resin composition measured at the position of the junction between the extruder and the die), Extruded into the guider from the die lip at a rate of 500 kg / hr and passed through a guider arranged in parallel with a gap of 28 mm in the thickness direction of the extruded foam while being foamed, and formed into a plate shape (shaped) to form plate-like styrene A resin-based extruded foam was produced.

  In Tables 5 to 15, evaluation of foam moldability of the obtained extruded foam plate, apparent density, widthwise vertical cross-sectional area, thickness, closed cell ratio, thickness direction average cell diameter, bubble deformation rate, foaming agent remaining amount, heat The conductivity, thermal conductivity decrease rate, and flame retardancy evaluation are shown. The thermal conductivity reduction rate is the value of the thermal conductivity of an extruded foam produced using a mixed resin of the styrene resin of the present invention and a styrene- (meth) acrylate copolymer, It is a value divided by the value of thermal conductivity of an extruded foam produced using only a styrene resin. Tables 16 and 17 show the bending properties of the obtained extruded foam plates.

  The M component in Tables 5 to 15 means the (meth) acrylic acid ester component, and the amount of the M component in the styrene resin mixture is contained in the styrene- (meth) acrylic acid ester copolymer. It is the value calculated | required by multiplying content of M component made by the compounding ratio of this copolymer in a styrene-type resin mixture.

In Tables 5 to 15, the blowing agent type MeCl is methyl chloride, i-B is isobutane, CO ₂ is carbon dioxide, DME is dimethyl ether, i-P is isopentane, and c-P is cyclopentane. To do. In addition, the ratio of the amount of foaming agent added is a molar ratio, and the amount added is the number of moles relative to 1 kg of the styrene resin mixture. For example, MeCl / i-B = 50/50 of Example 1 in Table 5 and 1.2 mol / kg are obtained by adding a blowing agent having a molar ratio of methyl chloride to isobutane of 50:50 per kg of styrenic resin mixture. It means adding 1.2 mol.

  The addition amount of the flame retardant masterbatch and the air conditioner masterbatch in Tables 5 to 15 is a value with respect to 100 parts by weight of the styrene resin mixture.

  The remaining amount of foaming agent and the thermal conductivity in Tables 5 to 15 are values after 100 days have passed since the foam was produced.

[Measurement of thermal conductivity]
In the present invention, the thermal conductivity was obtained by cutting out a test piece having no molded skin of 200 mm × 200 mm × 25 mm from the extruded foam immediately after production, and storing the test piece in an atmosphere of 23 ° C. and 50% humidity. 100 days after production, based on the flat plate heat flow meter method (two heat flow meters, high temperature side 35 ° C., low temperature side 5 ° C., average temperature 20 ° C.) described in JIS A 1412-2 (1999) using the test piece. The thermal conductivity was measured.

[Evaluation of foam moldability]
The foam moldability in Tables 5 to 15 was evaluated according to the following evaluation criteria.
◯: A good plate-like extruded foam having a good foamed state and having no waviness on the surface can be stably obtained.
X: A plate-like extruded foam having a poor foam state and a good surface state cannot be obtained.

[Flame retardance evaluation]
The flame retardancy evaluation in Tables 5 to 15 is described in the measurement method A of JIS A 9511 (2006) 5.13.1 as a test piece cut out from a plate-like extruded foam after the lapse of 5 days after production. Evaluation was made in accordance with flammability standards for extruded polystyrene foam insulation board.
For the measurement, five test pieces were cut out from one extruded foam plate and evaluated according to the following evaluation criteria. That is, when measuring the flammability of the measurement method A of 5 · 13 · 1,
A: Flame disappears within 3 seconds in all specimens.
○: The average burning time of 5 test pieces is within 3 seconds, but the flame does not disappear within 3 seconds in one or more test pieces.
X: The average burning time of 5 test pieces exceeds 3 seconds.

[Measurement of bending properties]
The bending properties of the extruded foams in Tables 16 and 17 were measured according to JIS K 7221-2 (1999). From a plate-like extruded foam after the lapse of 5 days from the production, a test piece without a molded skin is used so that the test piece has a length of 200 mm, a width of 50 mm, and a thickness of 25 mm. Along the width direction, the middle point in the width direction was cut out to be the center of the length. Using this test piece, the test was performed with a pressure wedge and a support base tip radius of 10 mm, a fulcrum distance of 150 mm, and a test speed of 10 mm / min, and bending fracture deflection and apparent flexural modulus were obtained. The bending fracture deflection means a bending deflection when the test piece is broken.

  The results of Examples 1 to 34 show that when a polystyrene resin extruded foam is produced based on the method of the present invention, a polystyrene resin extruded foam excellent in long-term heat insulation and flame retardancy can be easily produced. Is shown. Radiant heat transfer by adding styrene- (meth) acrylic acid ester copolymer to styrenic resin and extruding and foaming (meth) acrylic acid ester component in styrene resin mixture to a specific ratio As a result, an extruded foam having excellent long-term heat insulation and flame retardancy was obtained as compared with the case where no styrene- (meth) acrylate copolymer was added.

Furthermore, in Example 23, when a styrene- (meth) acrylic acid ester copolymer having a large amount of (meth) acrylic acid ester component is added to a styrene-based resin, styrene- (meta) having a small amount of (meth) acrylic acid ester component is added. ) Extruded foam in which only a styrene- (meth) acrylate copolymer containing a large amount of (meth) acrylate components is added to a styrene resin by extrusion foaming in combination with an acrylate copolymer (implemented) An extrudate foam having a mechanical strength comparable to that of the extrudate foam (Comparative Example 1) having a bending deformation greater than that of Example 2) and having only a styrene resin as a base resin was obtained.
Similarly, in Examples 24, 25, and 27-31, a foam having a larger bending fracture deflection than that of the extruded foam of Example 26 was obtained. In particular, in Examples 25 and 29-31, the extruded foam of Comparative Example 16 was obtained. An extruded foam exhibiting bending fracture deflection equal to or greater than that of the body was obtained.

  In order to investigate the factor of the above-mentioned bending physical property improvement, the dispersion state of the styrene resin and the styrene- (meth) acrylate copolymer in the foam was observed using a transmission electron microscope. 1 and 2 are photomicrographs of the foam cross-section obtained in Example 26, and FIGS. 3 and 4 are photomicrographs of the cross-section of the foam obtained in Example 25. 1 and 3 show a magnification of 10,000 times, and FIGS. 2 and 4 show a magnification of 40,000 times. In the figure, 1 is a foam cell membrane, and a styrene resin and a styrene- (meth) acrylate copolymer have a sea-island structure. The “island” equivalent part (light colored part) of 3 is a styrene- (meth) acrylic acid ester copolymer. From these photographs, when the styrene- (meth) acrylate copolymer having a high content of the (meth) acrylate component is mixed with the styrenic resin, it is more than mixing alone (Example 26). By using together a styrene- (meth) acrylic acid ester copolymer having a low content of (meth) acrylic acid ester component (Example 25), the styrene- (meth) acrylic acid ester copolymer becomes a styrenic resin. It can be seen that it is finely dispersed inside. As a result, in Example 25, it can be understood that the bending property is improved as compared with Example 26.

  The comparative example 1 is compared with Examples 1-9 and 23, Comprising: The example which does not mix a styrene- (meth) acrylic acid ester copolymer with a styrene resin is shown. In Comparative Example 1, since the styrene- (meth) acrylic acid ester copolymer was not added, the thermal conductivity was higher than that in the case where the styrene- (meth) acrylic acid ester copolymer was added. ing.

  The comparative example 2 is compared with Examples 1-4, Comprising: The example which reduced content of the (meth) acrylic acid ester component in a styrene-type resin mixture is shown. In Comparative Example 2, since the content of the component was too small, the effect of reducing the thermal conductivity of the molded product could not be obtained.

  The comparative example 3 is compared with Examples 1-4, Comprising: The example which increased content of the (meth) -acrylic acid ester component in a styrene resin mixture is shown. In Comparative Example 3, since the content of the component was too large, the effect of lowering the thermal conductivity of the molded product was sufficient, but even if the amount of flame retardant added was increased, JIS A 9511 (2006) The flame retardancy of measurement method A was not satisfied.

  The comparative example 4 is compared with Examples 1-4, Comprising: The example which used the styrene- (meth) acrylic acid ester copolymer independently is shown. In Comparative Example 4, since it is not a mixture of a styrene resin and a styrene- (meth) acrylic acid ester copolymer, but a styrene- (meth) acrylic acid ester copolymer alone, the (meth) acrylic acid ester component is Despite being contained in a large amount, the effect of lowering the thermal conductivity is small compared to the above mixture, and furthermore, the content of the component is too much, so even if the amount of flame retardant added is increased, JIS A 9511 (2006) The flame retardancy of the measuring method A was not satisfied.

  Comparative Example 5 is compared with Example 2 and shows an example in which a (meth) acrylic acid ester polymer is mixed with a styrene resin instead of a styrene- (meth) acrylic acid ester copolymer. . In Comparative Example 5, since a (meth) acrylic acid ester polymer not containing a styrene monomer unit was used, the foamability deteriorated due to extremely poor compatibility with the styrene resin, and a good foam was obtained. I couldn't.

  Comparative Example 6 is Example 10, Comparative Example 7 is Examples 11, 26, Comparative Example 8 is Example 12, Comparative Example 9 is Examples 13, 14, and Comparative Example 10 is Example 15. Example 11 is Example 16, Comparative Example 12 is Examples 17 and 18, Comparative Example 13 is Example 19, Comparative Example 14 is Example 20, Comparative Example 15 is Examples 21, 22 and Comparative Example No. 16 is respectively compared with Examples 24-34, and shows an example in which a styrene- (meth) acrylic ester copolymer is not mixed with a styrene resin. In Comparative Examples 6 to 16, since the styrene- (meth) acrylic acid ester copolymer was not added, the thermal conductivity was higher than that in the case where the styrene- (meth) acrylic acid ester copolymer was added. It is high.

FIG. 6 is a transmission electron micrograph (magnification: 10,000 times) of a cross-section of a foam film of a foam obtained in Example 26. FIG. It is a transmission electron micrograph (magnification: 40,000 times) of the cell membrane cross section of the foam obtained in Example 26. It is a transmission electron micrograph (magnification: 10,000 times) of the cell membrane cross section of the foam obtained in Example 25. It is a transmission electron micrograph (magnification: 40,000 times) of the cell membrane cross section of the foam obtained in Example 25.

Explanation of symbols

1 Cell membrane 2 Styrenic resin 3 Styrene- (meth) acrylate copolymer

Claims (4)

A method for producing a foam having an apparent density of 20 to 60 kg / m ³ and a thickness of 10 to 150 mm by extrusion foaming a foamable molten resin composition obtained by kneading a styrene resin mixture and at least a foaming agent and a flame retardant. The styrene resin mixture is made of a mixture of a styrene- (meth) acrylic acid ester copolymer (A) and a styrene resin (B), and the styrene- (meth) acrylic is in the styrene resin mixture. The (meth) acrylic acid ester component derived from the acid ester copolymer (A) is contained in an amount of 4 to 45% by weight based on the styrene resin mixture, and the styrene- (meth) acrylic acid ester copolymer (A ) Is a styrene-methyl methacrylate copolymer, and the methyl methacrylate composition in the styrene-methyl methacrylate copolymer is Method for producing a styrene resin extruded foam but is characterized in that 25 to 80% by weight. The styrene- (meth) acrylic acid ester copolymer (A) is a styrene-methyl methacrylate copolymer (C) having a methyl methacrylate component of 40 to 75% by weight and a methyl methacrylate component of 5% by weight. It consists of the styrene-methyl methacrylate copolymer (D) which is less than 40 weight% above , The manufacturing method of the styrene-type resin extrusion foam of Claim 1 characterized by the above-mentioned. The ratio between the styrene-methyl methacrylate copolymer (C) and the styrene-methyl methacrylate copolymer (D) is 90:10 to 50:50 in weight ratio. The manufacturing method of the styrene resin extrusion foamed board of description. The blowing agent is an aliphatic hydrocarbon having 3 to 5 carbon atoms, an alicyclic hydrocarbon having 3 to 6 carbon atoms, an aliphatic alcohol having 1 to 4 carbon atoms, or a dialkyl ether having 1 to 3 carbon atoms in an alkyl chain. The method for producing a styrenic resin extruded foam according to any one of claims 1 to 3, which is at least one selected from alkyl chlorides having 1 to 3 carbon atoms, carbon dioxide, and water .

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