JP2016113598A - Styrenic foam sheet and molded body using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a styrenic foam sheet having heat resistance, moldability and strength at a good balance and good in productivity and a molded body using the same.SOLUTION: There are provided: a styrenic foam sheet by foaming a styrenic resin (A) obtained by a monomer mixture (a) containing polybranched macromonomer (a1) having a plurality of branches and a plurality of polymerizable double bonds, a styrenic monomer (a2) and methacrylic acid (a3) as essential components with used percentage with the methacrylic acid (a3) in a range of 0.2 to 3 mass% in the monomer mixture (a); and a molded body using the same.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foam sheet obtained by foaming a resin composition containing a copolymer of a specific multi-branched macromonomer having a double bond at a branch end, a styrene monomer, and methacrylic acid. The present invention relates to a foam sheet having a better balance of formability, heat resistance, and strength than a styrene foam sheet.

  Styrenic resin sheets are mainly used as food packaging containers because of their excellent transparency and rigidity. In general, the styrene resin is a resin that can be easily foamed, can reduce the weight of the molded body, and can greatly contribute to resource saving. Furthermore, a recycling system has been established, and the recycling rate is higher than other materials.

  However, in recent years, due to the shortening of range-up time at convenience stores, microwave ovens with high output (high wattage) have been used, and applications that increase the range of lunch boxes that contain a large amount of liquid components have also increased. For this reason, higher heat resistance has been demanded for the bottom material using a food container lid and a foam sheet. Further, not only for food packaging applications but also for foam boards (PSB) used for display materials, heat insulating materials, and the like, there is a high demand for heat resistance, and heat resistant materials with excellent cost performance are desired.

  As a technique for improving the heat resistance of the styrene resin sheet, for example, a styrene-methacrylic acid copolymer obtained by copolymerizing 94 to 96% by mass of styrene monomer and 4 to 6% by mass of methacrylic acid is used. A technique for forming a foam sheet has been proposed (see, for example, Patent Document 1). Although this method produces a certain effect with respect to heat resistance, the secondary formability of the foam sheet and the strength of the molded body may be insufficient, and this is a thing that balances heat resistance, moldability, and strength. It was. Moreover, since the compatibility with polystyrene is low, there is a problem in that physical properties are lowered when a foamed sheet containing polystyrene as a main component is collected.

  Moreover, 0.005-0.8 mass% epoxidized soybean oil with respect to the resin composition containing the styrene-methacrylic acid copolymer which makes methacrylic acid content 0.2-4.0 mass% or There is also provided a foamed sheet obtained by adding epoxidized linseed oil and 0 to 0.5% by mass of a higher fatty acid metal salt and extrusion-foaming it (for example, see Patent Document 2).

  In Patent Document 2, when extrusion foaming is performed, the molecular weight of the resin is increased by an additive, whereby the strength of the molded body is maintained even when the expansion ratio is increased. Due to the progress of the reaction in the extrusion foaming process, problems such as generation of gels and contamination of the inner surface of the extrusion foaming device due to bleeding out of the surface of additives (epoxidized soybean oil, epoxidized linseed oil, higher fatty acid metal salt), etc. This is likely to occur and is inferior in productivity, and further improvement is required.

JP 2013-221128 A JP 2008-144025 A

  In view of these circumstances, the problem to be solved by the present invention is to provide a styrenic foam sheet having a good balance of heat resistance, moldability and strength, and good productivity, and a molded body using the same. is there.

  As a result of intensive studies to solve the above problems, the inventors of the present invention require a multibranched styrene-methacrylic acid resin obtained by copolymerizing a multibranched macromonomer, a styrene monomer, and methacrylic acid. The present inventors have found that a foamed sheet obtained by foaming a styrene resin contained as a component can solve the above problems, and have completed the present invention.

  That is, the present invention comprises a multi-branched macromonomer (a1) having a plurality of branches and a plurality of polymerizable double bonds, a styrene monomer (a2), and methacrylic acid (a3) as essential components. A styrene-based resin obtained by copolymerizing the monomer mixture (a), wherein the ratio of use with the methacrylic acid (a3) is 0.2 to 3 mass in the monomer mixture (a). % Styrene-based resin (A) is foamed, and a styrene-based foam sheet, which is formed by molding the styrene-based foam sheet, is provided.

  The styrene foam sheet of the present invention has a high molecular weight while maintaining the melt viscosity of the styrene-methacrylic acid copolymer by introducing a multi-branched structure into the styrene-methacrylic acid copolymer. It is possible to improve the brittleness, which is a weak point, and improve the moldability and physical strength while maintaining heat resistance, and can be suitably used for food applications such as heating in a microwave oven.

It is the chromatograph which measured molecular weight by GPC-MALLS. It is a log-log graph with the horizontal axis representing the molecular weight of the resin composition determined from GPC-MALLS and the vertical axis representing the radius of inertia. It is a simplified apparatus figure for carrying out continuous block polymerization of a styrene resin composition.

Hereinafter, the composition used for the foamed sheet of the present invention will be described in detail.
[Styrene resin]
The styrene resin used in the present invention has a multi-branched macromonomer (a1) having a plurality of branches and a plurality of polymerizable double bonds, a styrene monomer (a2), methacrylic acid (a3), Is a styrene-based resin obtained by copolymerizing the monomer mixture (a) having an essential component, and the ratio of use with the methacrylic acid (a3) is 0.2 in the monomer mixture (a). A multibranched copolymer (A1) obtained by copolymerizing the multibranched macromonomer (a1), the styrene monomer (a2) and methacrylic acid (a3). ), A copolymer (A2) that is a linear resin obtained by copolymerizing a styrene monomer (a2) and methacrylic acid (a3) that are simultaneously produced during copolymerization, and further a styrene monomer (a2) Homopolymer of It may contain a homopolymer of methacrylic acid (a3).

  Further, a copolymer (A2) which is a linear resin obtained by copolymerizing a styrene monomer (a2) and methacrylic acid (a3) produced in advance, a homopolymer of styrene monomer (a2), methacrylic acid ( The homopolymer of a3) may be mixed with a resin obtained by copolymerizing the hyperbranched macromonomer (a1), the styrene monomer (a2), and methacrylic acid (a3). The raw material monomer conversion of the resin is performed, and it is essential that methacrylic acid (a3) is used at 0.2 to 3% by mass in the monomer mixture.

  In the monomer mixture (a) which is a raw material of the styrene resin (A) used in the present invention, the ratio of use with methacrylic acid (a3) is in the range of 0.2 to 3% by mass. A foamed sheet obtained using such a resin has an excellent balance between heat resistance and moldability.

  It is preferable that the weight average molecular weight calculated | required by GPC-MALLS of the said styrene resin (A) used for this invention is the range of 150,000-700,000.

[GPC-MALLS]
When the molecular weight of the styrenic resin (A) used in the present invention is measured by GPC-MALLS, for example, a chromatograph shown in FIG. 1 is obtained. In FIG. 1, the peak on the low molecular weight side is P1, and the peak on the high molecular weight side is P2. The peak P1 is presumed to contain a linear resin and a resin with a low degree of branching. The peak P2 is presumed to contain mainly a multi-branched resin having a high degree of branching. The region of peak P2 includes a perpendicular line drawn from the highest point of peak P2 to the baseline (a dotted line drawn substantially parallel to the volume axis in FIG. 1), a baseline, and a molecular weight curve on the left side from the highest point. And a molecular weight curve formed when the region (1) is folded to the right side with the perpendicular as the axis of symmetry (in FIG. 1, a virtual line indicated by a dotted line on the right side of the perpendicular). This is a region formed by a region (2) surrounded by a molecular weight curve), a perpendicular, and a base line. The region of peak P1 is a portion obtained by subtracting the region of peak P1 composed of the region (1) and region (2) from the region surrounded by the molecular weight curve and the baseline.

[Blend ratio of resin in peak P1 region and resin in peak P2 region]
The mass ratio of the resin in the peak P1 region and the resin in the peak P2 region of the styrenic resin (A) used in the present invention is excellent in the balance between the strength and workability of the obtained sheet ( Resin in the region of peak P2) / (resin in the region of peak P1) = 30/70 to 70/30 is preferable, and 40/60 to 60/40 is more preferable. This ratio can be easily controlled by adjusting the use ratio of the hyperbranched macromonomer (a1), the styrene monomer (a2), and the methacrylic acid (a3), the type of chain transfer agent, and the amount used. .

[Slope of log-log graph]
Moreover, the slope in the region of molecular weight 250,000 to 10 million in the logarithmic graph with the horizontal axis representing the molecular weight obtained from GPC-MALLS of the styrene resin (A) used in the present invention and the vertical axis representing the inertial radius is It is most preferable that it is 0.25 to 0.55 in terms of expressing strength and moldability with an excellent balance. When the slope is larger than 0.55, the physical properties are closer to those of the linear resin. Conversely, when the slope is smaller than 0.25, the fluidity may be lowered due to an increase in molecular weight accompanying an increase in the degree of branching.

[Multi-branched macromonomer (a1)]
As the multi-branched macromonomer (a1) having a plurality of branches and having a plurality of polymerizable double bonds used in the present invention, a styrene resin excellent in the above properties can be easily obtained. The weight average molecular weight of the multibranched macromonomer (a1) (from the viewpoint of controlling the weight average molecular weight of the multibranched resin contained in the peak P2 to 10 million or less to suppress the generation of gel and ensuring fluidity ( Mw) is preferably in the range of 1,000 to 15,000, more preferably 3,000 to 8,000.

  The branched structure in the multi-branched macromonomer (a1) is not particularly limited, but all three bonds other than the electron-withdrawing group and the bond that is bonded to the electron-withdrawing group are bonded to the carbon atom. Those that are branched by secondary carbon atoms and those that form a branched structure by repeating structural units having an ether bond, an ester bond or an amide bond are preferred.

When the hyperbranched macromonomer (a1) forms a branched structure with the quaternary carbon, the electron withdrawing group content is 2.5 × 10 5 per g of the hyperbranched macromonomer (a1). it is preferably in the range of ^{-4 mmol~5.0} × ¹⁰ -1 mmol, more preferably in the range of ^{5.0 × 10 -4 mmol~5.0 × 10 -2} mmol.

  It is essential that the multi-branched macromonomer (a1) has two or more polymerizable double bonds per molecule. The content of the polymerizable double bond is preferably in the range of 0.1 to 5.5 mmol, and more preferably in the range of 0.5 to 3.5 mmol, per 1 g of the macromonomer (a1). When the amount is less than 0.1 mmol, it is difficult to obtain a high molecular weight multibranched copolymer (A1). When the amount exceeds 5.5 mmol, the molecular weight of the multibranched copolymer tends to increase excessively. is there. The polymerizable double bond is preferably present at the tip of the multi-branched macromonomer (a1).

  The multibranched macromonomer (a1) that can be used in the present invention includes a branched structure formed by repeating a structural unit having an ester bond, an ether bond or an amide bond, and two or more polymerizable groups in one molecule at the branch end. A multi-branched macromonomer (a1-i) having a double bond can be mentioned.

  In the multibranched macromonomer (a1-i-1) in which a structural unit having an ester bond is repeatedly formed to form a branched structure, the carbon atom adjacent to the carbonyl group of the ester bond forming the molecular chain is a quaternary carbon atom. A preferred embodiment is one in which a polymerizable double bond such as a vinyl group or an isopropenyl group is introduced into a multi-branched polyester polyol. Introducing a polymerizable double bond into a multi-branched polyester polyol can be carried out by an esterification reaction or an addition reaction.

  In the multi-branched polyester polyol, a substituent may be introduced into a part of the hydroxy group in advance by an ether bond or other bond, and a part of the hydroxy group may be oxidized or other reaction. It may be denatured. Further, in the hyperbranched polyester polyol, a part of the hydroxy group may be esterified in advance.

  Examples of the multi-branched macromonomer (a1-i-1) include a compound having one or more hydroxy groups, a carbon atom adjacent to the carboxy group being a quaternary carbon atom, and two or more hydroxy groups. It is obtained by reacting a monocarboxylic acid having a multi-branched polymer, and then reacting the hydroxyl group, which is a terminal group of the polymer, with an unsaturated acid such as acrylic acid or methacrylic acid or an acrylic compound containing an isocyanate group. Things. In addition, about the multibranched polymer which formed the branched structure by repeating the structural unit which has an ester bond, "Angew.Chem.Int.Ed.Engl.29" p138-177 (1990) by Mr. Tamalia etc. Have been described.

  Examples of the compound having at least one hydroxy group include a) aliphatic diol, alicyclic diol, or aromatic diol, b) triol, c) tetraol, d) sugar alcohols such as sorbitol and mannitol, e) anne Hydroenenea-heptitol or dipentaerythritol, f) α-alkyl glucoside such as α-methyl glycoside, g) monofunctional alcohol such as ethanol, hexanol, h) alkylene oxide having a weight average molecular weight of at most 8,000, or The hydroxy group containing polymer etc. which were produced | generated by making the derivative and the hydroxyl group in 1 or more types of compounds selected from any of said a) -g) react can be mentioned.

  Examples of the a) aliphatic diol, alicyclic diol and aromatic diol include, for example, 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, polytetrahydrofuran, dimethylolpropane, neopentylpropane, 2-propyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 1,3-butanediol, diethylene glycol, triethylene glycol , Polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol; cyclohexanedimethanol, 1,3-dioxane-5,5-dimethanol; 1,4-xylylenediethanol, 1-phenyl-1,2-ethanediol Etc. . Examples of the b) triol include trimethylolpropane, trimethylolethane, trimethylolbutane, glycerol, 1,2,5-hexanetriol, 1,3,5-trihydroxybenzene, and the like. Examples of c) tetraol include pentaerythritol, ditrimethylolpropane, diglycerol, and ditrimethylolethane.

  Examples of the monocarboxylic acid in which the carbon atom adjacent to the carboxyl group is a quaternary carbon atom and having two or more hydroxy groups include, for example, dimethylolpropionic acid, α, α-bis (hydroxymethyl) butyric acid, α , Α, α-tris (hydroxymethyl) acetic acid, α, α-bis (hydroxymethyl) valeric acid, α, α-bis (hydroxymethyl) propionic acid, and the like. By using the monocarboxylic acid, the ester decomposition reaction is suppressed and a multibranched polyester polyol can be formed.

  Further, it is preferable to use a catalyst when producing the multi-branched polyester polyol. Examples of the catalyst include organic tins such as dialkyltin oxide, halogenated dialkyltin, dialkyltin biscarboxylate, and stannoxane. Examples thereof include compounds, titanates such as tetrabutyl titanate, organic sulfonic acids such as Lewis acid and p-toluenesulfonic acid.

  Examples of the hyperbranched macromonomer (a1-i-2) in which a structural unit having an ether bond is repeated to form a branched structure include, for example, one hydroxy group in a compound having one or more hydroxy groups or cyclic ether compounds. By reacting the cyclic ether compound having the above, a multi-branched polymer is obtained, and then an unsaturated acid such as acrylic acid or methacrylic acid, an isocyanate group-containing acrylic compound, 4-chloromethyl is added to the hydroxy group which is a terminal group of the polymer. Examples thereof include those obtained by reacting halogenated methylstyrene such as styrene. Further, as a method for producing the multi-branched polymer, a compound containing one or more hydroxy groups and two or more hydroxy groups and a halogen atom, -OSO2OCH3 or -OSO2CH3, based on Williamson's ether synthesis method A method of reacting with is also useful.

  As the compound having one or more hydroxy groups, any of those mentioned above can be used, and as the cyclic ether compound having one or more hydroxy groups, for example, 3-ethyl-3- (hydroxymethyl) Examples include oxetane, 2,3-epoxy-1-propanol, 2,3-epoxy-1-butanol, and 3,4-epoxy-1-butanol. The compounds having one or more hydroxy groups used in the Williamson ether synthesis method may be those described above, but aromatic compounds having two or more hydroxy groups bonded to an aromatic ring are preferred. Examples of the compound include 1,3,5-trihydroxybenzene, 1,4-xylylenediethanol, 1-phenyl-1,2-ethanediol and the like. Examples of the compound containing two or more hydroxy groups and a halogen atom, —OSO 2 OCH 3 or —OSO 2 CH 3 include 5- (bromomethyl) -1,3-dihydroxybenzene, 2-ethyl-2- (bromomethyl) -1 , 3-propanediol, 2-methyl-2- (bromomethyl) -1,3-propanediol, 2- (bromomethyl) -2- (hydroxymethyl) -1,3-propanediol, and the like. In addition, when manufacturing the said multi-branched polymer, it is preferable to use a catalyst normally, and examples of the catalyst include BF3 diethyl ether, FSO3H, ClSO3H, and HClO4.

  In addition, examples of the multi-branched macromonomer (a1-i-3) in which a structural unit having an amide bond is repeated to form a branched structure include those having an amide bond in a repeating structure via a nitrogen atom in the molecule. A typical example is the generation 2.0 (PAMAM dentrimer) manufactured by Dentorite.

  Examples of the styrene monomer (a2) that can be used in the present invention include the following. Styrene and its derivatives; for example, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, alkyl styrene such as octyl styrene, fluorostyrene, chlorostyrene , Halogenated styrene such as bromostyrene, dibromostyrene and iodostyrene, nitrostyrene, acetylstyrene, methoxystyrene and the like.

  In the present invention, in addition to the hyperbranched macromonomer (a1), the styrenic monomer (a2), and methacrylic acid (a3), a monomer that can be copolymerized within a range that does not impair the heat resistance and workability of the resin composition. May be used. Examples of the copolymerizable monomer that can be used in the present invention include (meth) acrylic acid esters such as methyl methacrylate, butyl methacrylate, and butyl acrylate.

[Polymerization method of hyperbranched macromonomer (a1), styrene monomer (a2) and methacrylic acid (a3)]
By polymerizing the multi-branched macromonomer (a1), the styrene-based monomer (a2) and methacrylic acid (a3) with other monomers used in combination as necessary, polymerization is performed with a multi-branched resin. A styrenic resin (A) which is a mixture of a linear resin and a low-branched resin that are simultaneously generated depending on conditions is obtained. At this time, the above-mentioned multibranched macromonomer (a1) is preferably 50 ppm to 1%, more preferably 100 ppm to 3000 ppm (mass basis) with respect to the total amount of the styrene monomer (a2) and methacrylic acid (a3). By using the ratio, it is easy to produce a multi-branched resin, and it is easy to produce a resin for a styrene-based foam sheet used in the present invention.

  Moreover, the use ratio with methacrylic acid (a3) is the range of 0.2-3 mass% in a monomer mixture (a).

  Various commonly used polymerization methods of styrene monomers can be applied to the polymerization reaction. The polymerization method is not particularly limited, but bulk polymerization, suspension polymerization, or solution polymerization is preferable. Among them, continuous bulk polymerization is particularly preferable from the viewpoint of production efficiency.For example, by performing continuous bulk polymerization incorporating one or more stirred reactors and a tubular reactor in which a plurality of mixing elements having no moving parts are fixed. An excellent resin can be obtained. Although thermal polymerization can be performed without using a polymerization initiator, it is preferable to use various radical polymerization initiators. Moreover, what is used for manufacture of a normal polystyrene can be used for polymerization adjuvants, such as a suspending agent and an emulsifier required for superposition | polymerization.

  In order to reduce the viscosity of the reaction product in the polymerization reaction, an organic solvent may be added to the reaction system. Examples of the organic solvent include toluene, ethylbenzene, xylene, acetonitrile, benzene, chlorobenzene, dichlorobenzene, and anisole. , Cyanobenzene, dimethylformamide, N, N-dimethylacetamide, methyl ethyl ketone and the like. In particular, when it is desired to increase the amount of the hyperbranched macromonomer, it is preferable to use an organic solvent from the viewpoint of suppressing gelation. Thereby, the addition amount of the multi-branched macromonomer (a1) shown above can be dramatically increased to introduce a lot of branched structures, and gelation hardly occurs.

  The radical polymerization initiator is not particularly limited. For example, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) butane, 2,2-bis (4 , 4-di-butylperoxycyclohexyl) propane and other peroxyketals, cumene hydroperoxide, hydroperoxides such as t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, di Dialkyl peroxides such as -t-hexyl peroxide, diacyl peroxides such as benzoyl peroxide and disinamoyl peroxide, t-butyl peroxybenzoate, di-t-butyl peroxyisophthalate, t-butyl peroxide Pao such as oxyisylpropyl monocarbonate Siesters, N, N′-azobisisobutylnitrile, N, N′-azobis (cyclohexane-1-carbonitrile), N, N′-azobis (2-methylbutyronitrile), N, N′-azobis ( 2,4-dimethylvaleronitrile), N, N′-azobis [2- (hydroxymethyl) propionitrile] and the like, and these can be used alone or in combination.

  Furthermore, you may add a chain transfer agent so that the molecular weight of the resin obtained may not become too large. As the chain transfer agent, either a monofunctional chain transfer agent having one chain transfer group or a polyfunctional chain transfer agent having a plurality of chain transfer groups can be used. Examples of the monofunctional chain transfer agent include alkyl mercaptans and thioglycolic acid esters. Polyfunctional chain transfer agents include ethylene glycol, neopentyl glycol, trimethylol propane, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol and the like, the hydroxy group in thioglycolic acid or 3-mercaptopropionic acid And the like esterified with.

  In addition, long chain alcohols, polyoxyethylene alkyl ethers, polyoxyethylene lauryl ethers, polyoxyoleyl ethers, polyoxyethylene alkenyl ethers, and the like can be used to suppress gel formation of the resulting resin.

<Polymerization process>
In the polymerization step, a multi-branched macromonomer (a1), a styrene monomer (a2), and methacrylic acid are used as monomer components, and these are copolymerized to form a multi-branched copolymer that is a copolymer of these three components. A styrene resin (A) containing a polymer can be obtained. An example of the reaction vessel of the polymerization apparatus for obtaining the resin (A) in the present invention is shown in FIG. That is, the reaction solution is sent to the stirring reactor (I) by the pump (1), then sent to the circulation polymerization line (II) by the pump (2), and the inside of the circulation polymerization line (II) is sent by the pump (3). It circulates, and after circulation, it is sent to the non-circulation polymerization line (III). Here, the circulation polymerization line (II) is composed of three reactors composed of (4) to (6), and the non-circulation polymerization line (III) is composed of three reactors composed of (7) to (9). Is done.

  If necessary, add monomers and solvents between the stirred reactor (I) and the circulation polymerization line (II), or between the circulation polymerization line (II) and the non-circulation polymerization line (III). It is also possible to add.

<Devolatile process>
After the polymerization step, a devolatilization tank 1 and a devolatilization tank 2 for volatilizing unreacted monomers and solvent components are connected. It is preferable to adjust the devolatilization tank 1 and the devolatilization tank 2 to 4.0 kPa and 1.3 kPa under reduced pressure, respectively, and after passing through the devolatilization tank 1 and the devolatilization tank 2, they are pelletized. The styrene resin (A) used can be obtained.

  In the present invention, the styrene resin (A) obtained as described above is used, but if necessary, other styrene resin (B) and various additives may be used in combination as a styrene resin composition. Also good.

  As said other styrene resin (B), the homopolymer of styrene is mentioned. The styrene homopolymer may be linear or multi-branched, and the shape is not particularly limited, and resin pellets, pulverized foam sheets, and the like are preferably used.

  As the other styrene resin (B), rubber-modified styrene resin (B-1) can be used for the purpose of reinforcing the strength. Examples of the rubber-modified styrene resin (B-1) include impact-resistant polystyrene, which can be produced by polymerizing a styrene monomer in the presence of a rubber-like polymer. The usage ratio of these is 0 with respect to the total amount of the styrenic resin (A) and the rubber-modified styrenic resin (B-1) from the viewpoint of the balance between the desired heat resistance and strength of the foam sheet. It is preferably used in the range of 1 to 20% by mass.

  For the purpose of reinforcing the strength, a copolymer (B-2) of a styrene monomer and a (meth) acrylic acid ester may be used in combination. Although it does not specifically limit about content of (meth) acrylic acid ester, From a viewpoint of the balance of the heat resistance and intensity | strength made into the objective of a foam sheet, the said styrenic resin (A) and a copolymer (B-2) It is preferable to use in the range of 0.1 to 10% by mass with respect to the total amount.

  Further, as the styrene resin (B), a styrene thermoplastic elastomer (B-3) can be used for the purpose of reinforcing the strength. Specific examples of the styrenic thermoplastic elastomer (B-3) include a styrene-butadiene copolymer and its hydrogenated product, a styrene-isoprene copolymer and its hydrogenated product, and a methyl methacrylate-butadiene-styrene copolymer. Etc. The diene component content of these elastomers is not particularly limited, but a diene component content of 30% by mass or more with respect to all the monomer components constituting the elastomer is preferable from the viewpoint of the effect of improving the strength. The usage ratio of these is 0 with respect to the total amount of the styrenic resin (A) and the styrenic thermoplastic elastomer (B-3) from the viewpoint of the balance between the desired heat resistance and strength of the foam sheet. It is preferable to use in the range of 1-5 mass%.

  Examples of the various additives include plasticizers, antistatic agents, antioxidants, ultraviolet absorbers, lubricants, antiblocking agents, and heat stabilizers.

The thickness of the styrene foam sheet of the present invention is not particularly limited, but it is 0.5 to 6 from the viewpoint of ease of handling when obtaining a molded body by secondary processing and strength as a molded body. It is preferable to be in the range of 0.0 mm, and more preferably in the range of 0.7 to 4.0 mm. The bulk density is preferably in the range of 0.02 to 0.25 g / cm ³ from the viewpoint of strength.

  When molding a foam sheet, this resin is impregnated with a foaming agent, supplied to an extruder, heated and melted and kneaded, then extruded from a circular die, T-die, etc. It is possible to produce an extruded foam sheet by the method.

  As the foaming agent, a general general-purpose foam material can be used. Examples thereof include lower hydrocarbons such as propane, butane, pentane and hexane, halogen hydrocarbons such as methyl chloride, dichloromethane, trichloromonofluoromethane, and dichlorodifluoromethane, and carbon dioxide. In the case of handling operation in a normal extruder or low expansion ratio, chemical foaming using a baking soda-based foaming agent that generates carbon dioxide by heating is preferable.

  Furthermore, an inorganic compound can be used as a nucleating agent in order to control the amount and size of the foamed cells. A preferable inorganic compound is talc.

  Also, the mixing order of the resins is not particularly limited. For example, a method of adding a foaming agent to a styrene resin and supplying it to a melt kneader, or a master batch in which a foaming agent is previously kneaded at a high concentration in a part of the styrene resin. And a method of foam molding after kneading the master batch and the remaining styrene resin.

  In addition, if necessary, a method of melt-kneading other additives at the same time, or preparing a master batch in which a styrene resin and other resins and additives are melt-kneaded in advance, then the master batch, the styrene resin, and foaming You may use the method of melt-kneading an agent and foam-molding.

  Further, the temperature at the time of melt-kneading is preferably in the range of 180 to 260 ° C., preventing thermal deterioration of the styrene resin, and from the viewpoint of carbon dioxide generation efficiency when using a baking soda-based foaming agent. It is preferable that it is ° C.

  The die temperature of a circular die, T die, etc. is preferably in the range of 120 to 150 ° C. for stable foam molding.

  Although the magnification at the time of manufacturing a foam sheet is not specifically limited, It is preferable that it is 4-50 times from a viewpoint of maintenance of mechanical strength, the weight reduction by foaming, and the moldability balance.

  The styrenic foam sheet obtained above can be secondarily processed by thermoforming to form a molded body. As the thermoforming method, a hot plate contact heat forming method, a vacuum forming method, a vacuum / pressure forming method, a plug assist forming method, or the like is preferably used.

  The shape of the molded body is not particularly limited, such as various packs, cases, etc., but from the viewpoint of moldability and heat resistance, which are the characteristics of the styrene foam sheet of the present invention and the molded body, it is preferably for food packaging, Use as a container tray or a container is particularly preferable.

  It is also possible to bond a film to the front and back of the obtained foamed sheet or a molded product obtained by secondary molding for the purpose of imparting improved mechanical strength and chemical resistance. Specifically, it is also possible to thermally laminate a polystyrene-based inflation film or to bond an olefin-based film (CPP) using an adhesive.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention should not be limited to the scope of these examples. Hereinafter, “part” and “%” are based on mass unless otherwise specified.

[GPC-MALLS measurement]
GPC-MALS measurement of the styrene-based resin composition was performed under the conditions of Shodex HPLC, detector Wyatt Technology DAWN EOS, Shodex RI-101, column Shodex KF-806L × 2, solvent THF, and flow rate of 1.0 ml / min. . In addition, the analysis of the measurement of GPC-MALLS was performed by analysis software ASTRA manufactured by Wyatt, and the weight average molecular weight was obtained for the styrene resin composition, and the molecular weight of the resin composition obtained from GPC-MALLS was plotted on the horizontal axis. The slope in the region of molecular weight 250,000 to 10 million in the logarithmic graph with the radius of inertia as the vertical axis (automatically calculated by the software based on the measured value of only the linear portion obtained in the molecular weight range) The slope of the approximate line was determined.

[Melt Mass Flow Rate Measurement Method]
The measurement was performed according to JIS K7210. The measurement conditions are 230 ° C. and 37N.

[Measurement method of Vicat softening temperature]
The measurement was performed according to JIS K7206.

[Formability evaluation of foam sheet]
After producing the foam sheet, secondary molding into a container shape was performed. In the molding, a mold having a ratio (H / W) of depth (H) to opening (W) of 0.75 was used. The molding conditions were a foam sheet preheating time of 13 seconds and a heater temperature of 280 to 300 ° C.
A: The shape of the container is completely reproduced.
○: Some types are not reproduced,
Δ: A small hole is generated at the edge of the bottom of the container.
×: A large hole occurs at the bottom of the container

[Evaluation of heat resistance of foam sheet]
The secondary molded product of the foamed sheet was placed in an oven maintained at 110 ° C. for 10 minutes, and then the appearance of the container was visually evaluated in the following four stages.
A: No change
○: There is no problem in practical use although some surface burns are observed,
Δ: The container is slightly deformed,
×: Container is greatly deformed

[Strength evaluation]
A top-and-bottom compression test of the secondary molded product of the foam sheet was performed.
A: No problem,
○: Level that does not cause any practical problems
Δ: Difficult,
×: Easily breaks

Reference Example 1 Synthesis of Multibranched Macromonomer (Mm-1) <Synthesis of Multibranched Polyether Polyol 1>
To a 2 liter flask equipped with a stirrer, thermometer, dropping funnel and condenser, 50.5 g of ethoxylated pentaerythritol (5 mol-ethylene oxide-added pentaerythritol) and 1 g of BF 3 diethyl ether solution (50%) were added at room temperature, and 110 Heated to ° C. To this, 450 g of 3-ethyl-3- (hydroxymethyl) oxetane was slowly added over 25 minutes while controlling the exotherm due to the reaction. When the exotherm had subsided, the reaction mixture was further stirred at 120 ° C. for 3 hours and then cooled to room temperature. The resulting multi-branched polyether polyol had a weight average molecular weight of 3,000 and a hydroxyl value of 530.

<Synthesis of Multibranched Polyether 1 Having Methacryloyl Group and Acetyl Group>
In a reactor equipped with a Dean-Stark decanter equipped with a stirrer, a thermometer, a condenser, and a gas introduction tube, 50 g of the multi-branched polyether polyol obtained in the above-mentioned <Synthesis of multi-branched polyether polyol 1>, methacrylic acid 13 .8 g, 150 g of toluene, 0.06 g of hydroquinone and 1 g of paratoluenesulfonic acid, and stirring under normal pressure while blowing 7% oxygen-containing nitrogen (v / v) into the mixed solution at a rate of 3 ml / min. Heated. The amount of heating was adjusted so that the amount of distillate in the decanter was 30 g per hour, and heating was continued until the amount of dehydration reached 2.9 g. After completion of the reaction, the mixture was cooled once, 36 g of acetic anhydride and 5.7 g of sulfamic acid were added, and the mixture was stirred at 60 ° C. for 10 hours. Thereafter, in order to remove the remaining acetic acid and hydroquinone, it was washed with 50 g of 5% aqueous sodium hydroxide solution four times, and further washed once with 50 g of 1% aqueous sulfuric acid solution and twice with 50 g of water. To the obtained organic layer, 0.02 g of methoquinone was added, the solvent was distilled off while introducing 7% oxygen-containing nitrogen (v / v) under reduced pressure, and 60 g of a multibranched polyether having an isopropenyl group and an acetyl group was obtained. Obtained. The weight average molecular weight of the obtained multibranched polyether was 3,900, and the introduction ratios of isopropenyl group and acetyl group into the multibranched polyether polyol were 30 mol% and 62 mol%, respectively.

Reference Example 2 Synthesis of Multibranched Macromonomer (Mm-2) <Synthesis of Multibranched Polyether Polyol 2>
In a 1000 mL three-necked flask connected with nitrogen, air reflux condenser, magnetic stir bar and thermometer, 1.24 g (8.7 mmol) of boron trifluoride diethyl ether complex was dried and the peroxide was removed. Dilute with 273 g of methyl-t-butyl ether. In a separate container, 140 g (1.21 mol) of 3-hydroxymethyl-3-ethyloxetane and 70.0 g (1.21 mol) of propylene oxide were mixed, and the above three-necked flask was consumed with a metering pump for 5.5 hours. And dripped. At this time, the system was cooled by an ice bath as needed to keep the temperature in the system at 20 ° C. After completion of the dropwise addition, 63.0 g (1.08 mol) of propylene oxide was further added dropwise over 3 hours while keeping the temperature in the system at 20 ° C., and the mixture was further stirred for 4 hours. Here, 0.620 g (4.4 mmol) of boron trifluoride diethyl ether complex was added, and the mixture was further stirred at 20 ° C. for 6 hours. The reaction mixture was adsorbed and removed by adding hydrotalcite 10 times the weight of boron trifluoride diethyl ether complex used in the reaction and refluxing for 1 hour. After the hydrotalcite was filtered off, methyl-t-butyl ether was removed to obtain 267 g of a transparent and highly viscous multi-branched polyether polyol. This multi-branched polyether polyol has Mn = 2,876 g / mol, Mw = 7,171 g / mol, hydroxyl value = 253 mg · KOH / g, and 3-hydroxymethyl-3-ethyl on a molar basis from proton NMR. Oxetane: propylene oxide = 1: 1.9.

<Synthesis of multi-branched polyether 2 having acryloyl group>
In a 500 mL four-necked flask equipped with a Dean-Stark tube, nitrogen and air introduction tube, a stirrer, and a thermometer, the multi-branched polyether polyol obtained in the above <Synthesis of multi-branched polyether polyol 2> 155 g, 51 g of acrylic acid, 200 g of cyclohexane, 0.21 g of hydroquinone monomethyl ether, and 4 g (12.3 mmol) of dodecylbenzenesulfonic acid as a catalyst were added, and the temperature was raised to 82 ° C. under a mixed gas flow of nitrogen and air 2 to 1. . Cyclohexane reflux began, and water flow began gradually. Thereafter, when the temperature was raised to 85 ° C. and reacted for 18 hours, 60% of the theoretical dehydration amount was reached, so cooling was started. After cooling to around 30 ° C., 5% sodium hydroxide aqueous solution and 15% NaCl aqueous solution were added for washing. The hydroxyl group value of the obtained polymerizable unsaturated group-containing multi-branched polyether was 70 mg · KOH / g, and the acrylic group introduction rate of all hydroxyl groups was 60%.

Reference Example 3 Synthesis of Multibranched Macromonomer (Mm-3) <Synthesis of Multibranched Polyether 1 Having Styryl Group and Acetyl Group>
In a reactor equipped with a stirrer, a condenser equipped with a drying tube, a dropping funnel and a thermometer, 50 g of the multibranched polyether polyol obtained in the above-mentioned <Synthesis of multibranched polyether polyol 1>, 100 g of tetrahydrofuran and sodium hydride 4.3 g was added and stirred at room temperature. To this was added dropwise 26.7 g of 4-chloromethylstyrene over 1 hour, and the resulting reaction mixture was further stirred at 50 ° C. for 4 hours. After completion of the reaction, the reaction mixture was once cooled, 34 g of acetic anhydride and 5.4 g of sulfamic acid were added, and the mixture was stirred at 60 ° C. for 10 hours. Thereafter, the tetrahydrofuran was distilled off under reduced pressure, the resulting mixture was dissolved in 150 g of toluene, washed with 50 g of 5% aqueous sodium hydroxide solution to remove the remaining acetic acid, and further 50 g of 1% aqueous sulfuric acid solution. And once with 50 g of water. The solvent was distilled off from the obtained organic layer under reduced pressure to obtain 70 g of a multi-branched polyether having a styryl group and an acetyl group. The obtained multi-branched polyether had a mass average molecular weight of 4,800, and the styryl group and acetyl group introduction rates into the multi-branched polyether polyol were 38 mol% and 57 mol%, respectively.

Reference Example 4 Synthesis of Multibranched Macromonomer (Mm-4) <Synthesis of Multibranched Macromonomer Having Methacryloyl Group and Acetyl Group>
A four-necked flask was equipped with a stirrer, pressure gauge, condenser and saucer, to which 308.9 g of ethoxylated pentaerythritol and 0.46 g of sulfuric acid were added. Then, it heated to 140 degreeC and 460.5g of 2, 2- di (hydroxymethyl) propionic acid was added over 10 minutes. After 2,2-di (hydroxymethyl) propionic acid is completely dissolved and becomes a transparent solution, the pressure is reduced to 30 to 40 mmHg and the reaction is continued for 4 hours while stirring and the acid value becomes 7.0 mgKOH / g. I let you. Thereafter, 921 g of 2,2-di (hydroxymethyl) propionic acid and 0.92 g of sulfuric acid were added to the reaction solution over 15 minutes to obtain a transparent solution, and then the pressure was reduced to 30 to 40 mmHg, while stirring. The polyester polyol was obtained by reacting for a period of time. In a reaction vessel equipped with a 7% oxygen introduction tube, a thermometer, a Dean-Stark decanter equipped with a condenser, and a stirrer, 10 g of the polyester polyol produced above, 1.25 g of dibutyltin oxide, and 100 g of methyl methacrylate having an isopropenyl group And 0.05 g of hydroquinone were added, and the mixture was heated with stirring while blowing 7% oxygen at a rate of 3 ml / min. The amount of heating is adjusted so that the amount of distillate in the decanter is 15 to 20 g per hour, the distillate in the decanter is taken out every hour, and the corresponding amount of methyl methacrylate is added for 4 hours. Reacted. After completion of the reaction, methyl methacrylate was distilled off under reduced pressure, and 10 g of acetic anhydride and 2 g of sulfamic acid were added to cap the remaining hydroxy groups, followed by stirring at room temperature for 10 hours. After removing sulfamic acid by filtration and distilling off acetic anhydride and acetic acid under reduced pressure, the residue was dissolved in 70 g of ethyl acetate and washed 4 times with 20 g of 5% aqueous sodium hydroxide to remove hydroquinone. Further, it was washed twice with 20 g of a 7% aqueous sulfuric acid solution and twice with 20 g of water. To the obtained organic layer, 0.0045 g of methoquinone was added, and the solvent was distilled off while introducing 7% oxygen under reduced pressure to obtain 11 g of a hyperbranched macromonomer (Mm-3) having an isopropenyl group and an acetyl group. It was. The resulting multi-branched macromonomer (Mm-3) has a weight average molecular weight of 3,000, a number average molecular weight of 2,100, and a double bond introduction amount of 2.00 mmol / g, an isopropenyl group and an acetyl group. The introduction rates were 55 mol% and 36 mol%, respectively.

Reference Example 5 Synthesis of hyperbranched macromonomer (Mm-5) <Synthesis of PAMAM dendrimer having a styryl group>
To a reactor equipped with a stirrer, a condenser equipped with a drying tube, a dropping funnel and a thermometer, 50 g of a methanol solution (20%) of PAMAM dendrimer (Generation 2.0: manufactured by Dentritech) was added and stirred under reduced pressure. Methanol was distilled off. Subsequently, 50 g of tetrahydrofuran and 3.0 g of finely divided potassium hydroxide were added, and the mixture was stirred at room temperature. 4-chloromethylstyrene 7.0g was dripped at this over 10 minutes, and the obtained reaction mixture was further stirred at 50 degreeC for 3 hours. After completion of the reaction, the mixture was cooled and the solid was filtered, and then tetrahydrofuran was distilled off under reduced pressure to obtain 13 g of a PAMAM dendrimer having a styryl group. The resulting styryl group content of the dendrimer was 2.7 mmol / gram.

Reference Example 6 Synthesis of Multibranched Macromonomer (Mm-6) <Multibranched Polyether Polyol 2 Having Styryl Group and Acetyl Group>
A light-shielding reaction vessel equipped with a stirrer, a condenser, a light-shielding dropping funnel and a thermometer, and capable of nitrogen sealing. Under nitrogen flow, anhydrous 1,3,5-trihydroxybenzene 0.5 g, potassium carbonate 29 g, 18-crown -6 2.7 g and acetone 180 g were added, and a solution composed of 21.7 g of 5- (bromomethyl) -1,3-dihydroxybenzene and 180 g of acetone was added dropwise over 2 hours while stirring. Thereafter, the mixture was heated and refluxed with stirring until 5- (bromomethyl) -1,3-dihydroxybenzene disappeared. Thereafter, 9.0 g of 4-chloromethylstyrene was added, and the mixture was further heated and refluxed with stirring until the disappearance. Thereafter, 4 g of acetic anhydride and 0.6 g of sulfamic acid were added to the reaction mixture, and the mixture was stirred overnight at room temperature. After cooling, the solid in the reaction mixture was removed by filtration, and the solvent was distilled off under reduced pressure. The obtained mixture was dissolved in dichloromethane and washed three times with water, and then the dichloromethane solution was added dropwise to hexane to precipitate a multibranched polyether. This was filtered and dried to obtain 12 g of a multi-branched polyether polyol having a styryl group and an acetyl group. The mass average molecular weight was 3,200, and the styryl group content was 3.5 mmol / gram.

Reference Example 7 Synthesis of Multibranched Macromonomer (M-m7) <Synthesis of Multibranched Polyester Polyol Having Methacryloyl Group and Acetyl Group>
In a reaction vessel equipped with a 7% oxygen introduction tube, a thermometer, a Dean-Stark decanter equipped with a condenser, and a stirrer, 10 g of “Borton H20”, 1.25 g of dibutyltin oxide, and 100 g of methyl methacrylate having an isopropenyl group as a functional group And 0.05 g of hydroquinone were added, and the mixture was heated with stirring while blowing 7% oxygen at a rate of 3 ml / min. The amount of heating is adjusted so that the amount of distillate in the decanter is 15 to 20 g per hour, the distillate in the decanter is taken out every hour, and the corresponding amount of methyl methacrylate is added for 6 hours. Reacted.

  After completion of the reaction, methyl methacrylate was distilled off under reduced pressure, and 10 g of acetic anhydride and 2 g of sulfamic acid were added to cap the remaining hydroxy groups, followed by stirring at room temperature for 10 hours. After removing sulfamic acid by filtration and distilling off acetic anhydride and acetic acid under reduced pressure, the residue was dissolved in 70 g of ethyl acetate and washed 4 times with 20 g of 5% aqueous sodium hydroxide to remove hydroquinone. Further, it was washed twice with 20 g of a 7% aqueous sulfuric acid solution and twice with 20 g of water. To the obtained organic layer, 0.0045 g of methoquinone was added, and the solvent was distilled off while introducing 7% oxygen under reduced pressure to obtain 12 g of a hyperbranched polyester having an isopropenyl group and an acetyl group. The obtained multibranched polyester had a mass average molecular weight of 2860 and a number average molecular weight of 3770, and the introduction rate of isopropenyl group and acetyl group into the multibranched polyester polyol was 55% and 40%, respectively.

Example 1
A mixed solution comprising 98 parts of styrene monomer, 2 parts of methacrylic acid monomer, and 1000 ppm of the multi-branched macromonomer (Mm-1) obtained in Reference Example 1 with respect to the total amount of styrene monomer and methacrylic acid monomer, and 8 parts of toluene. Further, t-butyl peroxybenzoate as an organic peroxide was added at 150 ppm with respect to the total amount of styrene monomer and methacrylic acid monomer, and was continuously bulk polymerized under the following conditions using the apparatus shown in FIG. . The stirring reactor (I) was 110 to 130 ° C., and the circulation polymerization line (II) and the non-circulation polymerization line (III) were 115 to 170 ° C., respectively. From the reaction solution, unreacted monomers and solvent components are recovered in the devolatilization tank 1 and the devolatilization tank 2 installed after the non-recycling polymerization line (III) as the final reactor. The devolatilization tank 1 and the devolatilization tank 2 were set to 240 to 280 ° C. Thereafter, it passed through a single pipe and was converted into a strand and pelletized with a pelletizer to obtain a styrene resin (A-1).

  The obtained styrenic resin (A-1) was supplied to a tandem foam extrusion apparatus, butane gas was injected, and a die temperature was set to 135 ° C. to produce a foam sheet having a thickness of 2.0 mm. The obtained foamed sheet was vacuum-formed, and the secondary formability, heat resistance and strength were evaluated.

Example 2
The macromonomer was changed to Mm-2 obtained in Reference Example 2 to obtain a styrene resin (A-2).

Example 3
The macromonomer was changed to Mm-3 obtained in Reference Example 3 to obtain a styrene resin (A-3).

Example 4
The macromonomer was changed to Mm-4 obtained in Reference Example 4 to obtain a styrene resin (A-4).

Example 5
The macromonomer was changed to Mm-5 obtained in Reference Example 5 to obtain a styrene resin (A-5).

Example 6
The macromonomer was changed to Mm-6 obtained in Reference Example 6 to obtain a styrene resin (A-6).

Example 7
Except for changing the macromonomer to Mm-7 obtained in Reference Example 7 and obtaining a styrene resin (A-7), all were the same as Example 1.

Example 8
All were the same as Example 1 except that 97 parts of styrene monomer and 3 parts of methacrylic acid monomer were used as monomers to obtain a styrene resin (A-8).

Example 9
All were the same as Example 1 except having made the macromonomer 2000ppm and obtaining the styrene resin (A-9).

Example 10
All were the same as Example 1 except having made the macromonomer 200 ppm and obtained the styrene resin (A-10).

Example 11
Example 1 was the same as Example 1 except that 96 parts of styrene monomer, 3 parts of methacrylic acid monomer, and 1 part of butyl acrylate as a copolymerizable monomer were used to obtain a styrene resin (A-11).

Example 12
90 parts of styrene resin (A-8) obtained in the same manner as in Example 8, and rubber-modified styrene resin (B-1, DIC Corporation DIC Styrene GH-8300-5) as other styrene resin. All were the same as Example 1 except that 10 parts were used to produce a foam sheet.

Example 13
A styrene copolymer (B-2) was obtained in the same manner as in Example 1 except that 98 parts of styrene monomer, 2 parts of butyl acrylate, and 0 ppm of the macromonomer were used. Except for producing a foam sheet using 95 parts of the styrene resin (A-8) obtained in the same manner as in Example 8, and 5 parts of the styrene copolymer (B-2) as the other styrene resin, All were the same as Example 1.

Example 14
97 parts of the styrene resin (A-8) obtained in the same manner as in Example 8, and 3 parts of styrene-butadiene copolymer resin (B-3-1, Toughprene 125 manufactured by Asahi Kasei Chemicals Corporation) as the other styrene resin. All were the same as Example 1 except that the foamed sheet was produced using the part.

Example 15
97 parts of styrene resin (A-8) obtained in the same manner as in Example 8, and 3 parts of styrene-butadiene copolymer resin (B-3-2, Tuftec H1041 manufactured by Asahi Kasei Chemicals Corporation) as other styrene resin. All were the same as Example 1 except that the foamed sheet was produced using the part.

Example 16
97 parts of the styrene resin (A-8) obtained in the same manner as in Example 8, and methyl methacrylate-butadiene-styrene copolymer resin (B-3-3, 80% by mass of butadiene) as other styrene resins. All were the same as Example 1 except that 3 parts were used to produce a foam sheet.

Comparative Example 1
Example 1 was the same as Example 1 except that 100 parts of styrene monomer and 0 part of methacrylic acid monomer were used and that the macromonomer was 0 ppm.

Comparative Example 2
All were the same as Example 1 except the macromonomer was 0 ppm.

Comparative Example 3
Example 1 was the same as Example 1 except that 94 parts of styrene monomer and 6 parts of methacrylic acid monomer were used and that the macromonomer was 0 ppm.

Comparative Example 4
A styrene resin was obtained in the same manner as in Example 1 except that 97 parts of the styrene monomer, 3 parts of the methacrylic acid monomer, and 0 ppm of the macromonomer were used. Example 1 was the same as Example 1 except that 70 parts by mass of the styrene resin and 30 parts by mass of the rubber-modified styrene resin (B-1) were produced.

Comparative Example 5
Except that a foamed sheet was produced using 80 parts by mass of a styrene resin and 20 parts by mass of a styrene copolymer (B-2) obtained in the same manner as in Comparative Example 4, all of the same as Example 1.

Comparative Example 6
All the same as Example 1 except having produced the foam sheet using 90 mass parts of styrene-type resins obtained similarly to the comparative example 4, and 10 mass parts of styrene-butadiene copolymer resin (B-3-1). did.

Comparative Example 7
All the same as Example 1 except having produced the foam sheet using 90 mass parts of styrene resin obtained similarly to the comparative example 4, and 10 mass parts of styrene-butadiene copolymer resin (B-3-2). did.

Comparative Example 8
Example 1 except that a foamed sheet was prepared using 90 parts by mass of a styrene resin obtained in the same manner as in Comparative Example 4 and 10 parts by mass of methyl methacrylate-butadiene-styrene copolymer resin (B-3-3). And all the same.

Claims (9)

Monomer mixture having a multi-branched macromonomer (a1) having a plurality of branches and a plurality of polymerizable double bonds, a styrene monomer (a2), and methacrylic acid (a3) as essential components Styrenic resin obtained by copolymerizing (a), wherein the ratio of use with methacrylic acid (a3) is in the range of 0.2 to 3% by mass in the monomer mixture (a) A styrene-based foamed sheet obtained by foaming a resin-based resin (A). The styrene foam sheet according to claim 1, wherein the styrene resin (A) has a weight average molecular weight of 150,000 to 700,000 determined by GPC-MALLS. The styrenic foam sheet according to claim 1 or 2, further comprising (meth) acrylic acid ester in the monomer mixture (a). The rubber-modified styrene resin (B-1) is mixed with the styrene resin (A) to obtain a styrene resin composition, which is then foamed.
The rubber-modified styrene resin (B-1) is used in a proportion of the rubber-modified styrene resin (B-1) relative to the total amount of the styrene resin (A) and the rubber-modified styrene resin (B-1). The styrenic foam sheet according to any one of claims 1 to 3, wherein -1) is in the range of 0.1 to 20% by mass. The styrene resin (A) is mixed with a copolymer (B-2) of a styrene monomer and a (meth) acrylic ester to form a styrene resin composition and then foamed. ,
The proportion of the copolymer (B-2) of the styrene monomer and (meth) acrylic acid ester is based on the total amount of the styrene resin (A) and the copolymer (B-2). The styrene foam sheet according to any one of claims 1 to 3, wherein the copolymer (B-2) is in the range of 0.1 to 10% by mass. The styrenic resin (A) is mixed with a styrenic thermoplastic elastomer (B-3) to form a styrenic resin composition, which is then foamed.
The use ratio of the styrenic thermoplastic elastomer (B-3) is the styrenic thermoplastic elastomer (B) with respect to the total amount of the styrenic resin (A) and the styrenic thermoplastic elastomer (B-3). The styrene foam sheet according to any one of claims 1 to 3, wherein -3) is in the range of 0.1 to 5 mass%. The styrene foam sheet according to any one of claims 1 to 6, wherein the styrene foam sheet has a thickness of 0.5 to 6.0 mm and a bulk density of 0.02 to 0.25 g / cm ³ . A molded body comprising the styrene-based foamed sheet according to any one of claims 1 to 7 formed by a thermoforming method. The molded product according to claim 8, which is used for food packaging.