Method for producing styrene-based resin foam by extrusion foaming method, produced foam, and foamable resin composition used in the production method

Abstract

To provide a method that can produce a styrenic resin foam having high heat insulation performance, low density, and excellent moldability.SOLUTION: A method for producing a styrenic resin foam includes the step of mixing a styrenic resin with a foamer containing 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224 yd) of 1.1 mol or less relative to the styrenic resin 1 kg to give a foamable resin composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a styrene-based resin foam by extrusion foaming, the produced foam, and a foamable resin composition used in the production method. [Background technology]

[0002] Styrenic resin foams molded by extrusion foaming are used as heat insulating materials for buildings, etc. As a method for producing extruded styrene resin foams, a method is known in which a styrene resin and various additives such as a radiation reducing agent are added to an extruder, heated and melted to gel, a foaming agent is injected, the gel is cooled to a temperature suitable for foaming, and the gel is extruded into a low pressure region to continuously produce a foam. In addition, the styrene resin foams produced in this manner are known to have low thermal conductivity.

[0003] From the viewpoint of protecting the global environment, it is preferable to use blowing agents that do not destroy the ozone layer and have a small global warming potential, so carbon dioxide, dimethyl ether, ethanol, water, saturated hydrocarbons such as butane and propane, and alkyl chloride blowing agents such as methyl chloride and ethyl chloride are used. However, ether, alcohol, saturated hydrocarbon, and alkyl chloride blowing agents are flammable gases. On the other hand, in consideration of combustion during storage and fires after use in buildings, JIS A 9521 requires that foams be given flame retardant properties, and it is not preferable to use large amounts of these flammable gases as blowing agents.

[0004] In recent years, hydrofluoroolefins and hydrochlorofluoroolefins have been developed, which have an ozone depletion potential of 0, a low global warming potential, and are difficult to burn. These blowing agents have a lower thermal conductivity than hydrocarbon blowing agents such as butane, have a low escape rate from the foam, and are flame-retardant or non-flammable, making them good blowing agents for obtaining foams with low thermal conductivity.

[0005] It is known that extruded styrene resin foams having low thermal conductivity can be obtained by using the above-mentioned hydrofluoroolefin and hydrochlorofluoroolefin foaming agents (for example, Patent Document 1). However, as shown in the examples in Patent Document 1, the thermal conductivity of the obtained good foam is 0.022 W / mK or more, which is not sufficiently low. In addition, the density of the good foam is 45 Kg / m 3 This is not satisfactory from the viewpoint of cost. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2015-522696 Summary of the Invention [Problem to be solved by the invention]

[0007] Accordingly, an object of the present invention is to provide an extruded styrene-based resin foam which has high heat insulating performance, yet has low density, satisfies the flammability requirements specified in JIS A 9521, and is excellent in moldability. [Means for solving the problem]

[0008] The inventors have found that a styrene-based resin foam having high heat insulating performance, low density and excellent moldability can be produced by mixing a foaming agent containing a certain amount or less of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) with a styrene-based resin to obtain a foamable resin composition and extruding and foaming the composition, thereby completing the present invention.

[0009] That is, the present invention is a method for producing a styrene-based resin foam, comprising a step of mixing a styrene-based resin with a foaming agent containing 1.1 moles or less of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per 1 kg of the styrene-based resin to obtain a foamable resin composition.

[0010] In the present invention, it is preferable that the blowing agent further contains 0.3 to 0.8 mol of alkyl chloride per 1 kg of the styrene-based resin as a co-blowing agent, and it is preferable that the blowing agent contains 0.5 to 1.1 mol of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per 1 kg of the styrene-based resin.

[0011] Furthermore, in the present invention, the radiation reducing agent is preferably contained in an amount of 0.5 to 5.0 weight percent, more preferably 1.5 to 4 weight percent, based on 100 parts by weight of the styrene-based resin. The radiation reducing agent is preferably selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide.

[0012] The styrene-based resin foam produced by the present invention has a melting point of 30 to 41 kg / m 3 and a cell diameter of 0.1 mm or more. The styrene-based resin foam produced by the present invention preferably has a thermal conductivity of 0.022 W / m·K or less.

[0013] In another aspect of the invention, A styrene-based resin, (A) 0.1 to 1.1 moles of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per 1 kg of styrene-based resin, and (C) A foamable resin composition containing 0.5 to 5.0 weight percent of a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, relative to 100 weight parts of a styrene-based resin.

[0014] The present invention also relates to a styrene-based resin and (A) 0.1 to 1.1 moles of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per 1 kg of styrene-based resin, (B) 0.3 to 0.8 moles of alkyl chloride per 1 kg of styrene resin system; (C) a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, in an amount of 0.5 to 5.0 weight percent per 100 weight parts of the styrene-based resin; The foamable resin composition comprises: Furthermore, the foamable resin composition of the present invention preferably contains a brominated vinyl aromatic-butadiene copolymer.

[0015] The present invention also provides a styrene-based resin composition comprising 0.5 to 5.0 weight percent of a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, and 1.0 to 6.0 weight percent of a brominated vinyl aromatic butadiene copolymer, based on 100 parts by weight of the styrene-based resin, and having a density of 30 to 41 kg / m 3 In the extruded styrene-based resin foam having a cell diameter of 0.1 mm or more and a thermal conductivity of 0.022 W / m·K or less, the extruded foam contains 0.1 to 1.1 mol of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224 yd) per 1 kg of the extruded foam. Effect of the Invention

[0016] In the present invention, a styrene-based resin is mixed with a foaming agent containing 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) at a certain content or less to obtain a foamable resin composition, and then extrusion foaming is performed to produce a styrene-based resin foam having high thermal insulation performance, low density, and excellent moldability. The obtained extruded foam has high thermal insulation performance and low density, and therefore can be widely used in building materials such as insulation materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The styrene-based resin extrusion foam of the present invention is produced by heating and melting a styrene-based resin or a styrene-based resin composition to which various additives are optionally added to gel, adding a foaming agent containing 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) to the gel, and extruding and foaming the gel. First, the styrene-based resin and the styrene-based resin composition as raw materials will be described.

[0018] <Styrene-based resin> The styrene-based resin used in the present invention is not particularly limited, and examples thereof include polystyrene homopolymers obtained only from styrene monomer; random, block or graft copolymers obtained from styrene monomer and a monomer copolymerizable with styrene or a derivative thereof; brominated polystyrene; and modified polystyrenes such as rubber-reinforced polystyrene.

[0019] Examples of monomers copolymerizable with styrene include styrene derivatives such as methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene; vinyl compounds such as vinyltoluene, vinylxylene, and divinylbenzene; unsaturated compounds or derivatives thereof such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butadiene, and acrylonitrile; maleic anhydride, itaconic anhydride, and the like. These can be used alone or in a mixture of two or more. As the styrene-based resin, polystyrene homopolymer is particularly preferred. The weight-average molecular weight of the styrene-based resin is 100,000 to 300,000, preferably 150,000 to 250,000, and more preferably 180,000 to 220,000.

[0020] <Optional ingredients> In the present invention, radiation reducing agents, flame retardants, stabilizers, color pigments, cell regulators, etc. can be used as optional components. From the viewpoint of reducing thermal conductivity, it is preferable to add radiation reducing agents. In order for the resulting foam to satisfy the flammability specified in JIS A 9521, it is preferable to add flame retardants.

[0021] Examples of the radiation reducing agent include graphite, carbon black, and titanium oxide. The amount of the radiation reducing agent added to the styrene resin is 0.1 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight, and more preferably 1.5 to 4 parts by weight, per 100 parts by weight of the styrene resin. The radiation reducing agent is preferably selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide. The radiation reducing agent is preferably made into a master batch with a polystyrene resin in advance, taking into consideration dispersibility in the styrene resin, before being added to the heated and melted styrene resin. By using the radiation reducing agent, a foam having low thermal conductivity can be produced.

[0022] As the flame retardant, brominated butadiene-vinyl aromatic copolymer is preferred. Among the brominated butadiene-vinyl aromatic copolymers, brominated butadiene-styrene copolymer is preferred because it is easy to obtain high flame retardancy. The styrene-butadiene copolymer before bromination may be any of diblock copolymers (e.g., styrene-butadiene block copolymer), triblock copolymers (e.g., styrene-butadiene-styrene block copolymer), tetrablock copolymers (e.g., styrene-butadiene-styrene-butadiene block copolymer) and multiblock copolymers (e.g., styrene-butadiene-styrene-butadiene-styrene block copolymer). The styrene-butadiene copolymer may be prepared by any known method including random polymerization, but is preferably prepared by successive anionic polymerization or coupling reaction. Among these, brominated triblock copolymers such as brominated styrene-butadiene-styrene block copolymer are particularly preferred. The amount of the flame retardant added in the present invention is 1 to 6 parts by weight, preferably 2 to 4 parts by weight, based on 100 parts by weight of the polystyrene resin. The use of flame retardants allows the production of foams having a desired range of flammability.

[0023] As the stabilizer, for example, magnesium oxide, epoxy resin, cresol novolac type epoxy resin, alkyl phosphite, phosphorous ester, epoxidized soybean oil, etc. can be used.

[0024] The cell regulator may be polyethylene, polyethylene wax, talc, etc. The lubricant may be, for example, a metal stearate such as barium stearate.

[0025] In the present invention, a styrene-based resin containing any of the above-mentioned various additives is called a styrene-based resin composition, and a styrene-based resin composition containing a blowing agent or the like is called a foamable resin composition.

[0026] <Foaming agent> In the present invention, 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) is used as a blowing agent. HCFO-1224yd has E-type and Z-type isomers, but the physical properties are almost the same and are not particularly limited. HCFO-1224yd can be obtained from AGC Inc. under the trade name AMOLEA (registered trademark) 1224yd, for example.

[0027] The amount of HCFO-1224yd used may be 1.1 mol or less per kg of styrene-based resin, but is 0.1 to 1.1 mol, preferably 0.5 to 1.1 mol, more preferably 0.6 to 1.1 mol, and even more preferably 0.8 to 1.05 mol. Within this range, a foam having good foam moldability, low thermal conductivity, and good flame retardancy can be obtained.

[0028] <Co-foaming agent> In the present invention, an alkyl chloride can be used as the co-foaming agent. Since an alkyl chloride has a low thermal conductivity and a small nucleation effect, it has the effect of enlarging the bubble diameter that tends to become very small by HCFO-1224yd. In addition, when the foam contains a bromine-based flame retardant, it is preferable to use an alkyl chloride compared to water, etc., from the viewpoint of preventing corrosion in the process system. Examples of alkyl chloride include methyl chloride and ethyl chloride, and ethyl chloride is particularly preferable from the viewpoint of the effect of enlarging the bubble diameter and toxicity.

[0029] The amount of alkyl chloride used is 0.3 to 0.8 mol, preferably 0.3 to 0.6 mol, per 1 kg of styrene resin. By keeping it within this range, low thermal conductivity and a preferable cell diameter (0.1 to 0.5 mm) and foam cross-sectional area can be obtained when used in combination with HCFO-1224yd.

[0030] A co-foaming agent other than alkyl chloride may also be included, and a small amount of butanes may be added. The amount of butanes added is preferably 0.2 mol or less, more preferably 0.15 mol or less, and particularly preferably substantially 0 mol, per 1 kg of the styrene-based resin.

[0031] It is not preferable to include a blowing agent having a high nucleating effect, such as a lower hydrocarbon having 1 to 3 carbon atoms and an ether, because the inclusion of such a blowing agent has adverse effects, such as the cell diameter of the resulting foam becoming too small, resulting in poor moldability.

[0032] <Foamable resin composition> In this specification, the foamable resin composition refers to the above-mentioned styrene-based resin composition to which a foaming agent has been added. In the method for producing a foam of the present invention, the foamable resin composition is generated as an intermediate when a foaming agent is added, but the foamable resin composition can also be prepared by mixing the styrene-based resin composition and the foaming agent in advance. The foamable resin composition of the present invention contains a styrene-based resin and 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) as a foaming agent.

[0033] The content of HCFO-1224yd is 0.1 to 1.1 mol, preferably 0.5 to 1.1 mol, per 1 kg of styrene resin. The foamable resin composition preferably contains a radiation reducing agent, more preferably selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide. The content of the radiation reducing agent is 0.5 to 5.0 weight percent, preferably 1.5 to 4 weight percent, per 100 parts by weight of the styrene resin.

[0034] The foamable resin composition of the present invention preferably further contains an alkyl chloride as a co-foaming agent. The content of the alkyl chloride is 0.3 to 0.8 mol, preferably 0.3 to 0.6 mol, per 1 kg of the styrene resin. The foamable resin composition of the present invention preferably further contains a brominated vinyl aromatic-butadiene copolymer.

[0035] <Method of manufacturing styrene resin foam> In the present invention, a styrene-based resin foam can be produced by heating and melting a styrene-based resin or a styrene-based resin composition containing an optional additive, adding a foaming agent, and extruding and foaming the resulting mixture. For example, the styrene-based resin foam can be produced by feeding the main raw material styrene-based resin and various other additives into a hopper of an extruder, pressurizing and kneading the foaming agent, uniformly cooling the gel in a cooler, and extruding and foaming the gel from a die under atmospheric pressure.

[0036] The melting temperature when the styrene resin is heated and melted is 160 to 240° C., preferably 170 to 230° C., and more preferably 180 to 220° C., and the solid raw material is melt-kneaded by an extruder. The pressure when the foaming agent is injected is 110 to 200 kg / cm. 2 , more preferably 120 to 185 kg / cm 2 The solid raw material and the foaming agent melted by the extruder are kneaded by a mixer (rotation speed: 20 to 40 rpm, more preferably 25 to 35 rpm) and slowly cooled by a cooler. The optimal temperature for cooling and foaming the gel is 100 to 130°C, more preferably 110 to 125°C.

[0037] <Resin foam> The styrene-based resin foam obtained by the manufacturing method of the present invention has a thermal conductivity of 0.022 W / m K or less, measured by the measurement method specified in JIS A1412-2. The resin foam of the present invention can be produced by adding a radiation reducing agent such as graphite to the styrene-based resin composition, thereby producing a foam with low thermal conductivity.

[0038] In addition, this styrene-based resin foam has a density of 42 kg / m 3It is preferable that the cell diameter of the styrene-based resin foam is 0.1 to 0.5 mm. If the cell diameter is less than 0.1 mm, the density becomes high, making it difficult to obtain a desired cross-sectional area (width, thickness) of the foam, and furthermore, the foaming speed becomes fast, resulting in molding defects. If the cell diameter exceeds 0.5 mm, radiation becomes large and the thermal conductivity becomes large. In addition, it is preferable that the obtained styrene-based resin foam satisfies the flammability specified in JIS A 9521. The resin foam of the present invention can be produced by using a foamable resin composition containing a flame retardant, for example, a brominated butadiene-styrene copolymer.

[0039] Further, in a preferred embodiment, the present invention provides a styrene-based resin composition comprising 0.5 to 5.0 weight percent of a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, and 1.0 to 6.0 weight percent of a brominated vinyl aromatic-butadiene copolymer, based on 100 parts by weight of the styrene-based resin, and having a density of 30 to 41 kg / m 3 In the extruded styrene-based resin foam having a cell diameter of 0.1 mm or more and a thermal conductivity of 0.022 W / m·K or less, the extruded foam contains 0.1 to 1.1 mol of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224 yd) per 1 kg of the extruded foam. EXAMPLES

[0040] <Preparation method of extruded foam> First, a styrene resin A having a weight average molecular weight of 210,000 (a value measured by gel permeation chromatography in terms of standard polystyrene having a known molecular weight) was used.

[0041] In addition, as radiation reducing agents, graphite (artificial graphite manufactured by Ito Graphite Industries Co., Ltd.): 11.3 weight %, titanium oxide (Ti-PureR-104 manufactured by Chemours, average particle size 0.25 μm): 21.4 weight %, calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd.): 13 weight %, wax (Ricowax PE-520 manufactured by Clariant Japan): 8.5 weight %, and pigment (Leonol Blue FG-7330 manufactured by Toyo Ink Co., Ltd.): 1.3 weight % were mixed in advance with 44.5 weight % of styrene resin to prepare a master batch (master batch B) as radiation reducing agent B. Then, this radiation reducing agent B was added at a ratio of 7.8 weight parts to 100 weight parts of styrene resin A.

[0042] Furthermore, a flame retardant composition C (3.0 parts by weight of brominated butadiene-styrene copolymer (Emerald Innovation 3000 manufactured by Lanxess) as a flame retardant, 0.5 parts by weight of cresol novolac epoxy resin (ECN-1280 manufactured by Huntsman) as a stabilizer, 0.2 parts by weight of epoxidized soybean oil, and 0.2 parts by weight of alkyl phosphite (Doverphos S-9228 manufactured by Dover Chemical Corporation) were added to 100 parts by weight of styrene resin A) was added. In this way, the styrene resin containing styrene resin A, radiation reducing agent B, and flame retardant composition C was used as a base styrene resin.

[0043] <Production of foam> The above base styrene resin was charged into the hopper of the extruder. After the various blowing agents shown in Table 1 were further added under pressure, the solid raw material molten in the extruder and the blowing agent were kneaded with a mixer (rotation speed: 30 rpm) to obtain a foamable resin composition. The gel was uniformly cooled to 125°C in a cooler, and extruded through a die under atmospheric pressure to obtain a foam.

[0044] [Table 1]

[0045] <Analysis method> Various physical properties of the resulting foam were measured by the following methods. (Density) Weight of foam (kg) = Volume of foam (m 3 ) was calculated by dividing it by (Air bubble diameter) Measured by a method in accordance with ASTM D 3576. (Thermal conductivity) Measured by a method conforming to JIS A1412-2:1999 (average temperature 23°C). (Flammability) Measured using test method A described in JIS A9521:2017 Appendix C. The extrusion moldability of the foam was evaluated based on whether or not a good molded product was formed, and the surface defects of the foam were evaluated by visually checking the surface of the molded product for the presence or absence of voids.

[0046] Example 1 The base styrene resin (containing styrene resin A, radiation reducing agent B, and flame retardant composition C) was used, and 12.4 parts by weight of HCFO-1224yd (0.84 moles per kg of styrene resin) and 3.6 parts by weight of ethyl chloride (0.55 moles per kg of styrene resin) were added to 100 parts by weight of the styrene resin to produce a foam. As described above, radiation reducing agent B (containing 11.3% by weight of graphite and 21.4% by weight of titanium oxide) was contained at a ratio of 7.8 parts by weight per 100 parts by weight of styrene resin A, so that graphite was contained at 0.85% by weight and titanium oxide was contained at 1.61% by weight.

[0047] Example 2 A foam was produced under the same conditions as in Example 1, except that the above base styrene resin was used and 14.0 parts by weight of HCFO-1224yd (0.94 mol per kg of styrene resin) and 2.9 parts by weight of ethyl chloride (0.45 mol per kg of styrene resin) were added to 100 parts by weight of the styrene resin.

[0048] Example 3 A foam was produced under the same conditions as in Example 1, except that the above base styrene resin was used and 15.2 parts by weight of HCFO-1224yd (1.02 mol per kg of styrene resin) and 2.2 parts by weight of ethyl chloride (0.34 mol per kg of styrene resin) were added to 100 parts by weight of the styrene resin.

[0049] Comparative Example 1 A foam was produced under the same conditions as in Example 1, except that the above base styrene resin was used and 16.7 parts by weight of HCFO-1224yd (1.13 mol per kg of styrene resin) and 1.5 parts by weight of ethyl chloride (0.24 mol per kg of styrene resin) were added to 100 parts by weight of the styrene resin.

[0050] Comparative Example 2 A foam was produced under the same conditions as in Example 1, except that the above-mentioned base styrene resin was used and 17.5 parts by weight of HCFO-1224yd (1.18 mol per kg of styrene resin) and 1.5 parts by weight of ethyl chloride (0.23 mol per kg of styrene resin) were added to 100 parts by weight of the styrene resin. However, the bubble diameter was too small, and only defective molded products with defects on the surface were obtained.

[0051] [Table 2]

[0052] (Evaluation of Examples 1 to 3 and Comparative Examples 1 and 2) As described in Table 2 above, when 0.84 to 1.02 mol of HCFO-1224yd was added as a foaming agent to 1 kg of the base styrene resin (Examples 1 to 3), good extrusion moldability was exhibited, and a foam without surface defects was obtained. The obtained foam had a density of 32 to 41 (Kg / m3), a cell diameter of 0.12 to 0.31 mm, and an extremely good thermal conductivity of 0.0204 (W / mK) or less. When the ratio of HCFO-1224yd was increased to 1.13 mol and 1.81 mol (Comparative Examples 1 and 2), problems occurred in extrusion molding, and only defective molded products with surface defects were obtained.

[0053] <Change in HCFO-1224yd content> (Example 4) Using the above base styrene resin, a foam was produced under the same conditions as in Example 1, except that 9.5 parts by weight of HCFO-1224yd (0.64 mol per 1 kg of the styrene resin), 4.0 parts by weight of ethyl chloride (0.62 mol per 1 kg of the styrene resin), and 0.7 parts by weight of butane (0.12 mol per 1 kg of the styrene resin) were added to 100 parts by weight of the styrene resin.

[0054] (Examples 5 to 9) Using the above base styrene resin, as described in Table 3 below, a foam was produced under the same conditions as in Example 1, except that 8.0 to 1.0 parts by weight of HCFO-1224yd (0.54 to 0.07 mol per 1 kg of the styrene resin), 5.0 parts by weight of ethyl chloride (0.78 mol per 1 kg of the styrene resin), and 0.5 to 3.2 parts by weight of butane (0.09 to 0.55 mol per 1 kg of the styrene resin) were added to 100 parts by weight of the styrene resin.

[0055]

Table 3

[0056] (Evaluation of Examples 4 to 9) As shown in Table 3, the concentration of the blowing agent A was varied in the range of 0.64 to 0.07 mol per kg of styrene resin to produce foams, and foams with good extrusion moldability and no surface defects were obtained. The resulting foams had a density of 27 to 32 (Kg / m3), a cell diameter of 0.35 to 0.52 mm, and a thermal conductivity of 0.0210 to 0.0247 (W / mK).

[0057] <Change of co-foaming agent> Example 10 A foam was produced under the same conditions as in Example 1, except that 3 parts by weight of butane (0.55 mol per kg of styrene-based resin) was added instead of 3.6 parts by weight of ethyl chloride in Example 1.

[0058] Example 11 A foam was produced under the same conditions as in Example 1, except that 2.3 parts by weight of carbon dioxide (0.52 mol per kg of styrene-based resin) was added instead of 3.6 parts by weight of ethyl chloride.

[0059] Example 12 A foam was produced under the same conditions as in Example 1, except that 3.6 parts by weight of ethyl chloride was removed and only 12.4 parts by weight of HCFO-1224yd (0.84 mol per kg of styrene-based resin) was added to 100 parts by weight of the styrene-based resin.

[0060] Example 13 A foam was produced under the same conditions as in Example 3, except that 2.2 parts by weight of ethyl chloride was removed and only 15.2 parts by weight of HCFO-1224yd (1.02 mol per kg of styrene-based resin) was added to 100 parts by weight of the styrene-based resin.

[0061] Example 14 A foam was produced under the same conditions as in Example 3, except that 2 parts by weight of butane (0.34 mol per kg of styrene-based resin) was added instead of 2.2 parts by weight of ethyl chloride.

[0062] Comparative Example 3 A foam was produced under the same conditions as in Comparative Example 1, except that 1.5 parts by weight of ethyl chloride was removed and only 16.7 parts by weight of HCFO-1224yd (0.84 mol per kg of styrene-based resin) was added to 100 parts by weight of the styrene-based resin.

[0063] [Table 4]

[0064] (Evaluation of Examples 10 to 14 and Comparative Example 3) As shown in Table 4 above, the foams produced when butane or carbon dioxide was used instead of ethyl chloride as a co-blowing agent (Examples 10, 11, and 14) or when no co-blowing agent (ethyl chloride) was included (Examples 12 and 13) tended to have higher thermal conductivity in the order of butane, carbon dioxide, and no co-blowing agent, compared to the foam produced when ethyl chloride was included (Example 1). In addition, when no co-blowing agent was used, the density of the foam was significantly higher (55 to 56 kg / m3). When carbon dioxide was used, the bubble diameter of the foam was smaller than when ethyl chloride or butane was used. From the above, by using ethyl chloride as a co-blowing agent, a good foam with lower thermal conductivity was obtained.

[0065] <Change in content of radiation reducing agent> Example 15 A foam was produced under the same conditions as in Example 3 using a styrene resin prepared under the same conditions except that the ratio of radiation reducing agent B to 100 parts by weight of styrene resin A was 5.0 parts by weight instead of the base styrene resin (styrene resin A: 100 parts by weight, radiation reducing agent B: 7.8 parts by weight). Here, since the radiation reducing agent B was contained at a ratio of 5.0 parts by weight to 100 parts by weight of styrene resin A, the graphite was contained at 0.55% by weight and the titanium oxide was contained at 1.05% by weight.

[0066] (Example 16) A foam was produced under the same conditions as in Example 3 using a styrene resin prepared under the same conditions except that the ratio of radiation reducing agent B to 100 parts by weight of styrene resin A was 11.5 parts by weight instead of the base styrene resin (styrene resin A: 100 parts by weight, radiation reducing agent B: 7.8 parts by weight). Here, since the radiation reducing agent B was contained at a ratio of 11.5 parts by weight to 100 parts by weight of styrene resin A, the graphite was contained at 1.24% by weight and the titanium oxide was contained at 2.34% by weight.

[0067] <When not containing radiation reducing agent> Comparative Example 4 A foam was produced under the same conditions as in Example 3 using a styrene-based resin (containing styrene resin A and flame retardant composition C) prepared under the same conditions except that radiation reducing agent B was removed from the base styrene-based resin (containing radiation reducing agent B).

[0068] Comparative Example 5 A foam was produced under the same conditions as in Comparative Example 1 using a styrene-based resin (containing styrene resin A and flame retardant composition C) prepared under the same conditions except that radiation reducing agent B was removed from the base styrene-based resin (containing radiation reducing agent B).

[0069] (Comparative Example 6: No flame retardant) A foam was produced under the same conditions as in Comparative Example 1 using a styrene-based resin (containing styrene resin A and radiation reducing agent B) prepared under the same conditions except for removing flame retardant composition C from the base styrene-based resin (containing flame retardant composition C).

[0070] [Table 5]

[0071] (Evaluation of Examples 15 to 16 and Comparative Examples 4 to 6) As shown in Table 5 above, the ratio of radiation reducing agent B to 100 parts by weight of styrene resin A was changed from 7.8 parts by weight (Example 3) to 5.0 parts by weight (Example 15) and 11.5 parts by weight (Example 16) to produce foams. By increasing the ratio, the thermal conductivity tended to decrease. In addition, the foam produced under conditions that did not contain radiation reducing agent B had a significantly higher thermal conductivity (Comparative Example 4). In addition, the foam produced under conditions that did not contain flame retardant C (Comparative Example 6) was not necessarily satisfactory in terms of flammability and the like.

[0072] (Example 1: Use of HFO-1234ze) A foam was produced under the same conditions as in Example 1, except that the above-mentioned base styrene-based resin was used and 9.5 parts by weight of HFO-1234ze (0.84 mol per kg of styrene-based resin) and 3.6 parts by weight of ethyl chloride (0.55 mol per kg of styrene-based resin) were added as a foaming agent to 100 parts by weight of the styrene-based resin. However, the bubble diameter was too small, and only defective molded products with defects on the surface were obtained.

[0073] (Reference Example 2: Use of HCFO-1233zd) A foam was produced under the same conditions as in Example 1, except that 10.9 parts by weight of HCFO-1233zd (0.84 moles per kg of styrene resin) and 3.6 parts by weight of ethyl chloride (0.55 moles per kg of styrene resin) were added to 100 parts by weight of the styrene resin as a foaming agent, but only defective products with corrugated shapes and surface defects were obtained. The thermal conductivity, density, and flammability of this foam could not be measured, and the bubble diameter was 0.4 mm.

[0074] [Table 6]

[0075] (Evaluation of Reference Examples 1 and 2) As shown in Table 6 above, foams were produced using HFO-1234ze or HCFO-1233zd instead of HCFO1224yd as the foaming agent A. In either case, however, there was a problem with extrusion moldability, and only defective products with corrugated molding and surface defects were obtained.

[0076] As described above, in the present invention, a foam excellent in extrusion moldability was produced by using HCFO-1224yd as a foaming agent for a styrene-based resin. The obtained foam also had a low density and high thermal insulation performance.

Claims

1. A styrene-based resin, (A) 0.8 to 1.05 moles of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per 1 kg of styrene-based resin; (B) 0.3 to 0.6 moles of alkyl chloride per kg of styrene resin system; (C) 0.5 to 5.0 weight percent of a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, based on 100 weight parts of the styrene-based resin; (D) 1.0 to 6.0 weight percent of a brominated vinyl aromatic-butadiene copolymer; A foamable resin composition comprising:

2. A styrene-based resin, (A) 0.8 to 1.05 moles of 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) per kg of styrene-based resin, and (C) 0.5 to 5.0 weight percent of a radiation reducing agent selected from graphite, titanium oxide, or a mixture of graphite and titanium oxide, based on 100 weight parts of the styrene-based resin; (D) 1.0 to 6.0 weight percent of a brominated vinyl aromatic-butadiene copolymer; A foamable resin composition comprising:

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