JP2019001949A - Styrene resin composition, expanded sheet, molded article, and manufacturing method - Google Patents

Abstract

To provide a styrene resin composition excellent in molding processability, wide in molding condition width, and less in gel-like substance.SOLUTION: There is provided a styrene resin composition having content of a component with branch degree of 0.70 to 0.94, gelatinization degree of 1.00 to 1.25, and absolute molecular weight measured by using multiangle laser scattering detector (MALS) of 1,000,000 to 5,000,000 of 10.0 to 15.0%, a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) measured by using a gel permeation chromatography (GPC), (Mw/Mn) of 3.0 to 5.0, and peak top molecular weight (Mtop) measured by using GPC of 100,000 to 180,000.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a styrenic resin composition, a method for producing the same, a foamed sheet containing the styrenic resin composition, and a molded article comprising the foamed sheet.

  Styrene-based resins are excellent in transparency, molding processability, and the like, and thus are widely used in molding materials and food packaging materials for home appliances, office machine products, sundries, and housing equipment. In recent years, there has been a demand for thinning, lightening, and diversifying shapes of products, and a styrenic resin having a good appearance and excellent moldability is demanded. In the secondary molding of extruded sheets of styrenic resin, many moldings are performed at the same time, resulting in variations in the degree of heating of the sheet. With styrene resins with narrow molding conditions, the yield of molded products is poor. Has arisen. As a method for improving the molding processability of a styrene resin extruded sheet or the like, it is known that a method of containing an ultrahigh molecular weight component in a styrene resin is effective.

  As such a method, when the uniaxial elongation viscosity of the polystyrene-based resin composition is measured under a predetermined condition, Patent Document 1 describes the slope of the first-order approximation line of the nonlinear region in the logarithmic plot of the time-elongation viscosity curve and the above. The focus is on the ratio of the slope of the first-order approximation line of the linear region in the curve. Specifically, by setting this ratio in the range of more than 2.0 and less than 6.0 under the conditions of a temperature of 160 ° C. and a constant strain rate of 0.1 / second, weight reduction can be realized without deteriorating the physical properties of the container. It describes what you can do. In Patent Document 2, the melt mass flow rate of styrene resin, the total amount of styrene dimer and trimer, peak molecular weight (Mtop), Z average molecular weight (Mz), branching degree, and the content of low molecular weight saturated hydrocarbon are specified. It is described that a styrene-based resin foam sheet with less odor and excellent balance between strength, secondary moldability, and draw-down resistance can be obtained by setting the range.

JP 2014-189964 A JP 2016-113580 A

However, in Patent Document 1, when the uniaxial elongation viscosity of the polystyrene-based resin composition is measured under a predetermined condition, the slope of the first-order approximation line of the nonlinear region in the logarithmic plot of the time-elongation viscosity curve and the linear region in the above curve are obtained. Although it is described that the ratio of the slope of the first-order approximate line to a specific range is described, it has been found that the reduction of the gel-like substance is not sufficient and there is room for further improvement. In addition, in the styrene resin described in Patent Document 2, since a multi-branched structure is introduced using a multi-branched vinyl compound, the reduction of the gel-like substance is not sufficient, and there is room for further improvement. I understood.
Therefore, the present invention has been devised in view of such a conventional situation, and the object of the present invention is to provide a styrene resin composition having excellent molding processability, a wide range of molding conditions, and a small amount of gel substance. To provide things.

  In order to achieve the above-mentioned object, the present inventors have conducted extensive research. As a result, the degree of branching, the degree of gelation of the styrene-based resin composition, and an absolute molecular weight of 100 measured using a multi-angle light scattering detector (MALS). Content of 10,000 to 5,000,000 components, ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) measured using gel permeation chromatography (GPC) (Mw / Mn), and using GPC By controlling the measured peak top molecular weight (Mtop) to an appropriate range, it has been found that a styrenic resin composition having excellent molding processability, a wide range of molding conditions and a small amount of gel substance can be realized. It came to be completed.

That is, the present invention is as follows.
[1] The degree of branching is 0.70 to 0.94,
The degree of gelation is 1.00 to 1.25,
The content of components having an absolute molecular weight of 1,000,000 to 5,000,000 measured using a multi-angle light scattering detector (MALS) is 10.0 to 15.0%,
The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured using gel permeation chromatography (GPC) is 3.0 to 5.0,
A styrene resin composition having a peak top molecular weight (Mtop) measured by GPC of 100,000 to 180,000.
[2] The styrene resin composition according to [1], wherein the maximum rise ratio is 1.2 to 5.0.
[3] The total residual amount of styrene dimer and trimer is 0.01 to 0.30% by mass with respect to 100% by mass of the styrene resin composition, according to [1] or [2]. Styrenic resin composition.
[4] A foam sheet comprising the styrenic resin composition according to any one of [1] to [3] and having a thickness of 0.5 to 5.0 mm.
[5] A molded product comprising the foamed sheet according to [4].
[6] The method for producing a styrene resin composition according to any one of [1] to [3], wherein continuous solution polymerization or continuous bulk polymerization is used.

  According to the present invention, it is possible to provide a styrenic resin composition that is excellent in molding processability, has a wide range of molding conditions, and has little gel material.

It is a figure which shows the logarithm graph which plotted Henkey distortion | strain on the horizontal axis and extended viscosity on the vertical axis | shaft about the styrene resin composition obtained by the Example and the comparative example.

  Hereinafter, although an embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described, the present invention is not limited to this embodiment.

<< Styrene resin composition >>
The styrene resin composition of this embodiment has a branching degree of 0.70 to 0.94, a gelation degree of 1.00 to 1.25, and a multi-angle light scattering detector (MALS). The content of the component having an absolute molecular weight of 1,000,000 to 5,000,000 is 10.0 to 15.0%, and the weight average molecular weight relative to the number average molecular weight (Mn) measured using gel permeation chromatography (GPC). The ratio (Mw / Mn) of (Mw) is 3.0 to 5.0, and the peak top molecular weight (Mtop) measured using GPC is 100,000 to 180,000.

The degree of branching, gelation, content of components having an absolute molecular weight of 1 million to 5 million measured using MALS, and Mw / Mn and peak top molecular weight measured using GPC of the styrene resin composition of the present embodiment By controlling (Mtop) within the appropriate range as described above, it is possible to provide a styrenic resin composition having excellent molding processability, a wide range of molding conditions, and a small amount of gel substance.
Although not limited to theory, the styrenic resin composition of the present embodiment has a degree of branching, a content of components having an absolute molecular weight of 1 to 5 million measured using MALS, and Mw / Mn measured using GPC and By controlling the peak top molecular weight (Mtop) to an appropriate range, the moldability during extrusion is improved, the range of molding conditions is widened, and the gelation is controlled by controlling the gelation degree to an appropriate range. It is thought to be possible to be suppressed.
The degree of branching, gelation, content of components having an absolute molecular weight of 1 million to 5 million measured using MALS, and Mw / Mn and peak top molecular weight measured using GPC of the styrene resin composition of the present embodiment (Mtop) is, for example, in the case of obtaining a styrene resin composition by radical polymerization of a monovinyl compound, the content of a conjugated divinyl compound that may be optionally contained, the polymerization reaction temperature, and the polymerization reactor It can be controlled by the residence time, the type and amount of the polymerization initiator, the type and amount of the solvent used during the polymerization, and the like.

  The styrenic resin composition of the present embodiment includes, for example, a styrenic resin and optionally an additive or the like.

  Since the styrenic resin composition of the present embodiment is excellent in molding processability and has few gel-like substances, a foamed sheet having excellent appearance and a molded product thereof can be obtained, and various molded products can be obtained in a wider range of applications than before. be able to.

<Molecular weight of styrene resin composition>
The number average molecular weight (Mn) of the styrene resin composition of this embodiment is preferably 50,000 to 200,000, more preferably 60,000 to 180,000, and even more preferably 70,000 to 150,000. It is.
Moreover, it is preferable that the weight average molecular weight (Mw) of the styrene resin composition of this embodiment is 200,000 to 500,000, More preferably, it is 220,000 to 480,000, More preferably, it is 240,000 to 450,000. .
In addition, the Z average molecular weight (Mz) of the styrene resin composition of the present embodiment is preferably 600,000 to 2,000,000, more preferably 700,000 to 1,800,000, and even more preferably 800,000 to 1,600,000.

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the styrene resin composition of the present embodiment is 3.0 to 5.0, preferably 3.2 to 4.8. More preferably, it is 3.5-4.7, More preferably, it is 3.7-4.6. When Mw / Mn is less than 3.0, the fluidity is lowered, the molding processability is lowered, and the molding condition width may be narrowed. When Mw / Mn is larger than 5.0, the amount of low molecular weight components is extremely increased, and the strength of the molded product may be lowered.
In order to set Mw / Mn to 3.0 to 5.0, for example, a method of increasing the reaction temperature during polymerization in the order in which the reaction solution passes, a method of using a chain transfer agent, and various types of polymerization initiators are used. In the case of producing a resin by radical copolymerization of a monovinyl compound and a conjugated divinyl compound and / or a multi-branched vinyl compound, a method of making it functional (2, 3, or 4 functional), a conjugated divinyl compound or a multi-branched vinyl compound or its There is a method in which both are added in an amount of preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ mol with respect to 1 mol of the total amount of monovinyl compounds. Also, for example, in two reactors, there is a method in which polymerization is performed under conditions for polymerizing low molecular weight components and conditions for polymerizing high molecular weight components, respectively, and two polymerization solutions are merged, or a method in which further polymerization is performed after merging. . The conditions for polymerizing the low molecular weight component include, for example, a method of shortening the residence time in the reactor, a method of increasing the amount of the solvent to increase the polymerization temperature, and a method of using a chain transfer agent. Conditions for polymerizing the high molecular weight component include, for example, a method of reducing the amount of solvent and lowering the polymerization temperature, a method of using a polyfunctional polymerization initiator, a conjugated divinyl compound and / or a branched vinyl compound, or both. Preferably, there is a method of adding 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ mol with respect to 1 mol of the total amount of monovinyl compounds.

The peak top molecular weight (Mtop) of the styrene resin composition of the present embodiment is 100,000 to 180,000, preferably 110,000 to 180,000, more preferably 110,000 to 170,000, and even more preferably 120,000 to 160,000. It is. When Mtop is smaller than 100,000, the amount of low molecular weight components is extremely increased, and the strength of the molded product may be lowered. When Mtop is larger than 180,000, fluidity may be lowered and the molding condition width may be narrowed.
In order to make Mtop in the range of 100,000 to 180,000, for example, in a method using a chain transfer agent, or when a plurality of reactors are connected in series, the reaction solution passes through the reaction temperature at the time of polymerization. There are a method of increasing the order and a method of adding a chain transfer agent and a polymerization initiator to the subsequent reactor. Also, for example, in two reactors, there is a method in which polymerization is performed under conditions for polymerizing low molecular weight components and conditions for polymerizing high molecular weight components, respectively, and two polymerization solutions are merged, or a method in which further polymerization is performed after merging. . The conditions for polymerizing the low molecular weight component include, for example, a method of shortening the residence time in the reactor, a method of increasing the amount of the solvent to increase the polymerization temperature, and a method of using a chain transfer agent. Conditions for polymerizing the high molecular weight component include, for example, a method of reducing the amount of solvent and lowering the polymerization temperature, a method of using a polyfunctional polymerization initiator, a conjugated divinyl compound and / or a branched vinyl compound, or both. Preferably, there is a method of adding 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ mol with respect to 1 mol of the total amount of monovinyl compounds.

By setting Mw / Mn of the styrene resin composition to 3.0 to 5.0 and Mtop in the range of 100,000 to 180,000, a styrene resin composition having more excellent moldability and fluidity can be obtained. It is done.
In this disclosure, the number average molecular weight (Mn), the weight average molecular weight (Mw), the Z average molecular weight (Mz), and the peak top molecular weight (Mtop) of the styrene-based resin composition are determined using gel permeation chromatography (GPC). Is a measured value.

<Content of components having an absolute molecular weight of 1,000,000 to 5,000,000>
In the styrene resin composition of the present embodiment, the content of components having an absolute molecular weight of 1,000,000 to 5,000,000 is 10.0 to 15.0%, preferably 11.0 to 14.5%, more preferably 12. 0.0 to 14.0%. By setting the content of the component having an absolute molecular weight of 1,000,000 to 5,000,000 in the range of 10.0 to 15.0%, a styrene resin composition having excellent molding processability and less gel material can be obtained.
In order to set the content of the component having an absolute molecular weight of 1,000,000 to 5,000,000 to 10.0 to 15.0%, for example, a method using a polyfunctional polymerization initiator, a method of adding a conjugated divinyl compound, or a conjugate There is a method in which a divinyl compound and a hyperbranched vinyl compound are added simultaneously. For example, when a styrene-based resin composition is obtained by radical copolymerization by optionally adding a conjugated divinyl compound and / or a multi-branched vinyl compound to a monovinyl compound, the conjugated divinyl compound and / or the multi-branched vinyl compound The addition amount is preferably 4.0 × 10 ^{−6 to} 8.0 × 10 ⁻⁴ mol per vinyl group with respect to 1 mol of the total amount of monovinyl compound (that is, conjugated divinyl having two vinyl groups). In the case of a compound, it is preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ ). The number average molecular weight (Mn) of the conjugated divinyl compound and the hyperbranched vinyl compound is preferably 850 to 100,000. In the production of styrene-based resins, there is a method in which the amount of solvent is reduced to 0 to 20% and the reaction temperature is set to 80 to 140 ° C.
In the present disclosure, the content of components having an absolute molecular weight of 1,000,000 to 5,000,000 in the styrene resin composition is a value calculated using a multi-angle light scattering detector (MALS).

<Degree of branching>
The degree of branching of the styrene resin composition of this embodiment is 0.70 to 0.94, preferably 0.72 to 0.93, more preferably 0.75 to 0.92, and still more preferably 0.79. ~ 0.90. When the degree of branching is less than 0.70, there are too many branches and the molecular weight per branch chain is small, so the number of entanglement points is reduced, the entanglement is unraveled at high strain, and sufficient moldability is achieved. It may not be obtained. When the degree of branching is greater than 0.94, there are few branches and a sufficient entanglement effect between polymer chains may not be obtained.
In order to set the degree of branching to 0.70 to 0.94, a method using a polyfunctional polymerization initiator, a method of adding a conjugated divinyl compound, or a method of simultaneously adding a conjugated divinyl compound and a multibranched vinyl compound There is. For example, when a styrene-based resin composition is obtained by radical copolymerization by optionally adding a conjugated divinyl compound and / or a multi-branched vinyl compound to a monovinyl compound, the conjugated divinyl compound and / or the multi-branched vinyl compound The addition amount is preferably 4.0 × 10 ^{−6 to} 8.0 × 10 ⁻⁴ mol per vinyl group with respect to 1 mol of the total amount of monovinyl compound (that is, conjugated divinyl having two vinyl groups). In the case of a compound, it is preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ ). The number average molecular weight (Mn) of the conjugated divinyl compound and the hyperbranched vinyl compound is preferably 850 to 100,000.
In the present disclosure, the degree of branching is a value calculated by the procedure described in the section “Example” described later.

<Degree of gelation>
The gelation degree of the styrene resin composition of this embodiment is 1.00-1.25, Preferably it is 1.01-1.15, More preferably, it is 1.01-1.12, More preferably, it is 1. 01 to 1.10. By setting the degree of gelation in the range of 1.00 to 1.25, it is possible to suppress an increase in branching as the molecular weight increases, and thus the gel-like substance in the styrene-based resin composition can be reduced. In addition, when the product stays in production equipment such as a reactor for a long period of time, the amount of the gel-like substance to be generated can be reduced, so that productivity can be improved.
In order to set the gelation degree to 1.00 to 1.25, a method using a polyfunctional polymerization initiator, a method of adding a conjugated divinyl compound, or a conjugated divinyl compound and a multibranched vinyl compound are added simultaneously. There is a way. For example, when a styrene-based resin composition is obtained by radical copolymerization by optionally adding a conjugated divinyl compound and / or a multi-branched vinyl compound to a monovinyl compound, the conjugated divinyl compound and / or the multi-branched vinyl compound The addition amount is preferably 4.0 × 10 ^{−6 to} 8.0 × 10 ⁻⁴ mol per vinyl group with respect to 1 mol of the total amount of monovinyl compound (that is, conjugated divinyl having two vinyl groups). In the case of a compound, it is preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ ). The number average molecular weight (Mn) of the conjugated divinyl compound and the hyperbranched vinyl compound is preferably 850 to 100,000.
In the present disclosure, the gelation degree is a value calculated according to the procedure described in the section “Examples” described later.

<Melt Mass Flow Rate (MFR)>
The melt mass flow rate (MFR) of the styrene resin composition of this embodiment is preferably 0.5 to 5.0 g / 10 minutes. More preferably, it is 0.6-4.0 g / 10min, More preferably, it is 0.7-3.5g / 10min, Especially preferably, it is 0.8-3.0g / 10min. By setting the melt mass flow rate in the range of 0.5 to 5.0 g / 10 min, a styrene resin composition excellent in molding processability and fluidity can be obtained.
In order to set MFR to 0.5 to 5.0 g / 10 minutes, for example, a method of setting Mw / Mn of the styrene resin composition to 3.0 to 5.0 and setting Mw to 250,000 to 500,000. Alternatively, there is a method of adding 0.01 to 10.0% by mass of a plasticizer such as liquid paraffin with respect to 100% by mass of the styrene resin composition.
In the present disclosure, the melt mass flow rate is a value measured at 200 ° C. and a load of 49 N in accordance with ISO1133.

<Maximum rise ratio>
The maximum rising ratio of the styrene resin composition of the present embodiment is preferably 1.2 to 5.0, more preferably 1.3 to 4.8, and still more preferably 1.4 to 4.6. In the present specification, the “maximum rising ratio” means (extension viscosity in the nonlinear region of the maximum rising strain / extension viscosity in the linear region of the maximum rising strain), and “maximum rising strain” means that the extension viscosity is the maximum. This means Henkey distortion. The maximum rise ratio is an index representing the degree of strain hardening at the maximum rise strain. The greater the maximum rise ratio, the greater the degree of strain hardening and the better the moldability. If the maximum rise ratio is less than 1.2, sufficient deep drawing formability may not be obtained, or the molding condition width tends to be narrow. If the maximum rise ratio is larger than 5.0, the elongational viscosity at the time of molding becomes too low, which is not preferable from the viewpoint of productivity.
In order to set the maximum rise ratio to 1.2 to 5.0, for example, the content of components having a degree of branching of 0.70 to 0.94 and an absolute molecular weight of 1,000,000 to 5,000,000 is 10.0 to 15.0. There is a method to make%.
In the present disclosure, the maximum rise ratio is a value calculated by the procedure described in the section “Example” described later.

<Total residual amount of styrene dimer and trimer>
When the styrene resin composition of this embodiment is produced by radical polymerization reaction of a styrene monomer, the total residual amount of styrene dimer and trimer in the styrene resin composition is preferably Is 0.01 to 0.30% by mass with respect to 100% by mass of the styrene-based resin composition, more preferably 0.01 to 0.25% by mass, and still more preferably 0.02 to 0.20% by mass. is there. When the total residual amount of styrene dimer and trimer is 0.01 to 0.30% by mass, there will be less eye cracks during secondary molding, and the yield of molded products with good appearance will be improved. Or the odor of the molded product can be reduced.
In order to reduce the total amount of styrene dimer and trimer to 0.01 to 0.30% by mass with respect to 100% by mass of the styrene resin composition, for example, to reduce the amount generated during polymerization In addition, there are a method of reducing the reaction temperature to 80 to 140 ° C. and a method of adding 100 to 2000 ppm by mass of a polymerization initiator to generate many initiator radicals. Moreover, in order to reduce the amount generated by heat or shearing of the molten resin, a method of lowering the degree of vacuum to 50 kPa or less when unreacted monomer or solvent is devolatilized, or a thermal decomposition inhibitor described later is 100 to 3000. There is a method of adding mass ppm.
In the present disclosure, the total residual amount of styrene dimer and trimer is a value measured using gas chromatography (GC).

<Styrene resin>
<Method for producing styrene resin>
As a manufacturing method of the styrene resin of this embodiment, the method of manufacturing by radical copolymerizing a monovinyl compound, a conjugated divinyl compound, and / or a multibranched vinyl compound is mentioned, for example.
Hereinafter, as an example, a method for producing a styrene resin by radical copolymerization of a monovinyl compound, a conjugated divinyl compound and / or a multibranched vinyl compound will be described in detail.

<Monovinyl compound>
The monovinyl compound in the present embodiment may be composed of only a styrene compound (monomer) or may be composed of a compound having another monovinyl group copolymerizable with the styrene compound together with the styrene compound. The monovinyl compound is not particularly limited as long as it can be copolymerized with a styrene compound in addition to a styrene compound, and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth). Examples thereof include vinyl compounds such as acrylate and (meth) acrylonitrile, and dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, maleic anhydride, maleimide, and nucleus-substituted maleimide. Examples of the styrene compound include styrene, α-methyl styrene, paramethyl styrene, ethyl styrene, propyl styrene, butyl styrene, chlorostyrene, and bromostyrene, and styrene is preferable.
As content of a styrene-type compound, 50 mol% or more is preferable among content of a monovinyl compound, More preferably, it is 70 mol% or more, More preferably, it is 90 mol% or more.

<Conjugated divinyl compound>
The conjugated divinyl compound in the present embodiment is preferably a compound having a number average molecular weight (Mn) of 850 to 100,000 and having at least two conjugated vinyl groups in the molecule.
Further, the conjugated divinyl compound in the present embodiment is preferably not a network but a chain, and the main chain may or may not have a side chain. This is because the chain shape allows the molecular chain to have a more linear shape, which tends to improve the entanglement effect. The side chain preferably has, for example, 6 or less carbon atoms, more preferably 4 or less carbon atoms.
Furthermore, the conjugated vinyl group in the conjugated divinyl compound can be located arbitrarily in the molecule, but two of the at least two conjugated vinyl groups are located at different ends in the molecule. It is preferable. When the conjugated divinyl compound is a chain, the two conjugated vinyl groups are more preferably located at different ends of the main chain (that is, both ends of the main chain are conjugated divinyl groups). More preferably). When the conjugated vinyl group is located at the terminal, the polymerization reactivity can be increased.
Further, when the conjugated divinyl compound is a chain and has three or more conjugated vinyl groups, it is preferable that two conjugated vinyl groups among the three or more conjugated vinyl groups are located at the end. More preferably, all three or more conjugated vinyl groups are located at the end.
When the number of conjugated vinyl groups in the conjugated divinyl compound is large, the branching point increases, and there is a possibility that gelation is likely to occur in the process of recovering the reactor and raw materials, and the transparency of the styrene resin deteriorates. In addition, the reactor and molding machine need to be cleaned, and productivity may be reduced. From these viewpoints, the number of conjugated vinyl groups of the conjugated divinyl compound is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. From the same viewpoint, it is particularly preferable that the conjugated divinyl compound has two conjugated vinyl groups.
Here, in the present specification, the term “terminal” for a molecule includes not only the position (atom) at the end of the molecule but also a position close to the position at the end of the molecule, Specifically means the end corresponding to about 20% of the extended chain length of the molecule. The conjugated vinyl group in the conjugated divinyl compound is located at the end corresponding to 15% of the extended chain length of the conjugated divinyl compound molecule from the viewpoint of improving the reactivity with the monovinyl compound and suppressing gelation. More preferably, it is more preferably located at the end corresponding to 10%, and even more preferably located at the end corresponding to 5%.

  In this embodiment, the conjugated vinyl group refers to an olefinic double bond copolymerizable with a monovinyl compound, and a structure that forms a conjugated system with the olefinic double bond (for example, but not limited to, a carbonyl group, an aryl group, etc.) It is group which has. The conjugated vinyl group is not particularly limited, and examples thereof include an acryloyl group and an aryl group substituted with a vinyl group, and the structure having a conjugated vinyl group in the conjugated divinyl compound is not particularly limited. , (Meth) acrylate, urethane (meth) acrylate, aromatic vinyl, maleic acid, fumaric acid and the like. The at least two conjugated vinyl groups may be the same or different from each other.

The number average molecular weight (Mn) of the conjugated divinyl compound of this embodiment is preferably 850 to 100,000, more preferably 1000 to 80000, still more preferably 1200 to 80000, still more preferably 1500 to 60000, and particularly preferably. 1500-30000. When the number average molecular weight (Mn) is less than 850, since the distance between the conjugated vinyl groups of the conjugated divinyl compound is short, the distance between the polymer chains bonded to the conjugated divinyl compound becomes short, and a sufficient entanglement effect cannot be obtained. The molding processability may be inferior. When the molecular weight exceeds 100,000, the distance between the conjugated vinyl groups of the conjugated divinyl compound becomes longer, and the reactivity of the conjugated vinyl group at the terminal is lowered (the molecular weight of the conjugated divinyl compound is large, so the terminal conjugated vinyl group reacts). The amount of high molecular weight component produced may be reduced.
In the present disclosure, the number average molecular weight (Mn) of the conjugated divinyl compound means the number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC).

  The main chain structure of the conjugated divinyl compound of the present embodiment is not particularly limited, and examples thereof include polyolefins such as polyethylene, polypropylene and polyisoprene, polystyrene, polybutadiene, hydrogenated polybutadiene, polyphenylene ether, polyester, polyphenylene sulfide and the like. .

  Specific examples of the conjugated divinyl compound include (hydrogenated) polybutadiene-terminated (meth) acrylate (“(hydrogenated)” refers to a hydrogenated or non-hydrogenated compound; the same applies hereinafter), polyethylene. Terminal di (meth) acrylate compounds such as glycol terminal (meth) acrylate, polypropylene glycol terminal (meth) acrylate, ethoxylated bisphenol A terminal (meth) acrylate, and ethoxylated bisphenol F terminal (meth) acrylate, and (hydrogenated) Polybutadiene terminated urethane acrylate, polyethylene glycol terminated urethane acrylate, polypropylene glycol terminated urethane acrylate, ethoxylated bisphenol A terminated urethane acrylate, and ethoxylated bisphenol F terminated urethane acrylate Over preparative terminated urethane acrylate compounds such as and the like. For example, in the case of polypropylene glycol terminal (meth) acrylate, the number of bonds of propylene glycol as a repeating unit is determined so that the number average molecular weight (Mn) is 850 to 100,000. The conjugated divinyl compound is preferably (hydrogenated) polybutadiene-terminated (meth) acrylate, polystyrene-terminated (meth) acrylate, or polyphenylene ether-terminated divinyl from the viewpoint of compatibility with the styrene resin. “Terminal” and “both ends” in the compound name mean that a conjugated vinyl group is located at both ends.

<Content of conjugated divinyl compound>
The content of the conjugated divinyl compound in the styrene-based resin of the present embodiment is preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ mol, more preferably 5.0 with respect to 1 mol of the total amount of monovinyl compounds. × 10 ^{−6 to} 3.5 × 10 ⁻⁴ mol, more preferably 1.5 × 10 ^{−5 to} 3.0 × 10 ⁻⁴ mol, and even more preferably 2.0 × 10 ^{−5 to} 2.5 × 10 ^-4 mol. When the content is less than 2.0 × 10 ⁻⁶ mol, sufficient entanglement between the polymers is difficult to occur, strain hardening does not occur, or the degree of strain hardening is small, so that the thickness of the molded product is low. It may be uniform or the molded product may be broken during molding, and the molding processability may be inferior. On the other hand, when the content exceeds 4.0 × 10 ⁻⁴ mol, a lot of gel material is generated and the appearance and the like of the molded product may be poor.
In the present disclosure, the content of the conjugated divinyl compound relative to 1 mol of the total amount of the monovinyl compound is a value measured using ¹ H-NMR and ¹³ C-NMR.

<Multi-branched vinyl compound>
In the multi-branched vinyl compound in the present embodiment, the multi-branch means having one or more branch structures, and more specifically, a star-shaped branch structure, a pon-pon type branch structure, a graft branch structure, It means having an H-type branched structure.
The number average molecular weight (Mn) of the multi-branched vinyl compound is preferably 850 to 100,000, more preferably 1000 to 80000, still more preferably 1200 to 80000, still more preferably 1500 to 60000, and particularly preferably 1500 to 30000. It is. When the number average molecular weight (Mn) is less than 850, the distance between the vinyl groups is short, so the distance between the polymer chains bonded to the conjugated divinyl compound is short, and a sufficient entanglement effect cannot be obtained. May be inferior. When the molecular weight exceeds 100,000, the distance between the vinyl groups becomes long, and the reactivity of the vinyl group decreases (the molecular weight of the multi-branched vinyl compound is so large that the terminal vinyl group becomes difficult to react). The amount produced may decrease.
In the present disclosure, the number average molecular weight (Mn) of the multi-branched vinyl compound is a value measured using gel permeation chromatography (GPC).

  A hyperbranched vinyl compound is compoundable by the method of Unexamined-Japanese-Patent No. 2016-113580 and Unexamined-Japanese-Patent No. 2016-113598, for example. For example, divinyl aromatic compounds such as divinylbenzene and diisopropenylbenzene, aliphatics represented by ethylene glycol di (meth) acrylate, alicyclic (meth) acrylates, styrene, ethyl vinylbenzene and the like There is a method of synthesizing a multi-branched vinyl compound by cationic polymerization of a monovinyl compound and a terminal modifier such as 2-phenoxyethyl methacrylate. In addition, a method of esterifying or adding a vinyl group, for example, a polymerizable double bond such as an isopropenyl group, to a polyhydric alcohol or polyester polyol having a multi-branched structure and having a plurality of hydroxyl groups can be mentioned. . Here, the polyhydric alcohol having a multi-branched structure and having a plurality of hydroxyl groups is preferably an alcohol having 2 to 100 hydroxyl groups and having 70 to 3000 carbon atoms.

<Content of multi-branched vinyl compound>
The content of the multi-branched vinyl compound in the styrene resin of the present embodiment is preferably 2.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁴ mol, more preferably 5. 0 × 10 ^{−6 to} 3.5 × 10 ⁻⁴ mol, more preferably 1.5 × 10 ^{−5 to} 3.0 × 10 ⁻⁴ mol, even more preferably 2.0 × 10 ^{−5 to} 2.5 × 10 ^-4 mol. When the content is less than 2.0 × 10 ⁻⁶ mol, sufficient entanglement between the polymers is difficult to occur, strain hardening does not occur, or the degree of strain hardening is small, so that the thickness of the molded product is low. It may be uniform or the molded product may be broken during molding, and the molding processability may be inferior. On the other hand, when the content exceeds 4.0 × 10 ⁻⁴ mol, a lot of gel material is generated and the appearance and the like of the molded product may be poor.

<Polymerization process>
Examples of the polymerization method of the styrene resin of the present embodiment include known styrene polymerization methods such as a bulk polymerization method, a solution polymerization method, and a suspension polymerization method. These polymerization methods may be batch polymerization methods or continuous polymerization methods, and are preferably continuous polymerization methods from the viewpoint of productivity. Examples of the continuous bulk polymerization method include, for example, a raw material solution containing monomers by adding and mixing a monovinyl compound, a conjugated divinyl compound having a conjugated vinyl group, and a solvent, a polymerization catalyst, and a chain transfer agent as necessary. To prepare. In a facility equipped with one or more reactors arranged in series and / or in parallel and a devolatilizer for a devolatilization step for removing volatile components such as unreacted monomers, the raw material solution is added. Examples of the method include continuous feeding and stepwise polymerization.

  Examples of the reactor include a complete mixing type reactor, a laminar flow type reactor, and a loop type reactor in which a part of the polymerization liquid is withdrawn while the polymerization proceeds. There is no restriction | limiting in particular in the order of arrangement | sequence of these reactors.

  When polymerizing the styrene resin of the present embodiment, a polymerization solvent can be used as necessary from the viewpoint of controlling the polymerization reaction. The polymerization solvent is generally used for adjusting the polymerization rate, molecular weight and the like in continuous bulk polymerization and continuous solution polymerization. The polymerization solvent is not particularly limited, and examples thereof include alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene, ketones such as acetone and methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and cyclohexane. The amount of the polymerization solvent used is not particularly limited, but is usually 1 to 50% by mass as the composition in the polymerization reactor from the viewpoints of controlling gelation, improving productivity, increasing molecular weight, and the like. It is preferable that it is 3 to 40% by mass.

  Moreover, when superposing | polymerizing a polymerization raw material in order to obtain the styrene resin of this embodiment, polymerization initiators, such as an organic peroxide, and a chain transfer agent can be contained in a polymerization raw material composition. The polymerization initiator is not particularly limited, but organic peroxides such as 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, and n-butyl- Peroxyketals such as 4,4-bis (t-butylperoxy) valerate, dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide, acetyl peroxide, and isobutyryl peroxide Diacyl peroxides, peroxydicarbonates such as diisopropylperoxydicarbonate, peroxyesters such as t-butylperoxyacetate, ketone peroxides such as acetylacetone peroxide, and hydroperoxides such as t-butylhydroperoxide Mention may be made of the earth and the like. It is preferable to use 0.005-0.08 mass% of polymerization initiators with respect to the monovinyl compound. The chain transfer agent is not particularly limited, and examples thereof include α-methylstyrene dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan. The chain transfer agent is preferably used in an amount of 0.01 to 0.50% by mass relative to the monovinyl compound.

<Volatilization process>
As the devolatilization device, for example, a normal devolatilization device such as a flash drum, a biaxial devolatilizer, a thin film evaporator, an extruder, or the like can be used. A volatile extruder or the like is used. Examples of the arrangement of the devolatilizer include, for example, one using a vacuum devolatilization tank with a heater, one connected in series with two vacuum devolatilization tanks with a heater, and vacuum devolatilization with a heater. The thing etc. which connected the volatilization tank and the devolatilization extruder in series are mentioned. In order to reduce volatile components as much as possible, a vacuum devolatilization tank with a heater connected in two stages in series or a vacuum devolatilization tank with a heater and a devolatilization extruder connected in series is preferable. .

  The conditions for the devolatilization step are not particularly limited. For example, when the polymerization of the monovinyl compound is performed by bulk polymerization, the unreacted monovinyl compound is finally preferably 50% by mass, more preferably 40% in the styrene resin. Polymerization can proceed until the mass is less than or equal to mass%. By devolatilization treatment, volatile components such as unreacted substances (monovinyl compounds) and / or solvents can be removed.

  The temperature of the devolatilization treatment is usually about 190 to 280 ° C. The pressure of the devolatilization treatment is preferably 0.1 to 50 kPa, more preferably 0.13 to 13 kPa, still more preferably 0.13 to 7 kPa, and particularly preferably 0.13 to 1.3 kPa. As the devolatilization method, for example, it is desirable to devolatilize through a method of devolatilization by heating under reduced pressure, an extruder designed to remove volatile components, or the like.

The content of the styrenic resin in the styrenic resin composition is preferably 50% by mass or more,
70 mass% or more is more preferable.

<Additives, etc.>
The styrene resin composition of the present embodiment may optionally contain additives and the like, for example, rubber-reinforced aromatics such as HIPS resin and MBS resin as components containing rubber as necessary. You may contain about 1-50 mass% of aromatic vinyl-type thermoplastic elastomers, such as vinyl resin and SBS. Moreover, in order to suppress the thermal decomposition of the polymer | macromolecule in the collection | recovery process of an unreacted monomer, styrene-type resin composition is 2- [1- (2-hydroxy-3,5-di-t-phenylpentyl) ethyl, for example. ] Processing stabilizers such as -4,6-di-t-phenylpentyl acrylate may be included. Moreover, thermal deterioration inhibitors such as 2- [1- (2-hydroxy-3,5-di-t-phenylpentyl) ethyl] -4,6-di-t-phenylpentyl acrylate, stearic acid, zinc stearate , Higher fatty acids such as calcium stearate and magnesium stearate and salts thereof, lubricants such as ethylene bisstearyl amide, plasticizers such as liquid paraffin, antioxidants, and the like in a range that does not impair the purpose of this embodiment. May be. In addition, additives commonly used in the field of styrenic resins, such as flame retardants and colorants, may be combined in a range not impairing the object of the present embodiment and contained in the styrenic resin composition. The additive is not particularly limited, and examples thereof include flame retardants such as hexabromocyclododecane, and colorants such as titanium oxide and carbon black. Further, when the styrene resin is used as a pellet, ethylene bisstearylamide, zinc stearate, magnesium stearate, or the like may be used as an external lubricant for the pellet.

  Antioxidants generally stabilize peroxide radicals such as hydroperoxy radicals generated during thermoforming or exposure to light, or decompose peroxides such as hydroperoxides generated. It is a possible ingredient. Although it does not specifically limit as antioxidant, For example, a hindered phenolic antioxidant and a peroxide decomposer are mentioned. The hindered phenol-based antioxidant can be used as a radical chain inhibitor, and the peroxide decomposer can decompose the peroxide generated in the system into more stable alcohols to prevent auto-oxidation. Examples of the hindered phenol antioxidant include, but are not limited to, 2,6-di-tert-butyl-4-methylphenol, styrenated phenol, n-octadecyl-3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2-t-butyl-6- (3-t-butyl-2-hydroxy-5- Methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, 4,4 ′ -Butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), alkylated bisphenol , Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, and 3,9-bis [2- [3- (3-t-butyl-4- Hydroxy-5-methylphenyl) -propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxyspiro [5 · 5] undecane. Examples of the peroxide decomposer include, but are not limited to, organic phosphorus peroxide decomposition such as trisnonylphenyl phosphite, triphenyl phosphite, and tris (2,4-di-t-butylphenyl) phosphite. As well as dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, pentaerythrityltetrakis (3-laurylthiopro Pionate), ditridecyl-3,3′-thiodipropionate, and organic sulfur peroxide decomposers such as 2-mercaptobenzimidazole. The addition amount of the antioxidant is preferably 0.01 parts by mass or more and 1 part by mass or less, and more preferably 0.1 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the styrene resin in the styrene resin composition. It is below mass parts.

  Examples of the flame retardant include, but are not limited to, for example, hexabromocyclododecane, brominated SBS block polymer, and 2,2-bis (4 ′ (4 ′ () from the viewpoint of flame retardancy and compatibility with styrene-based resins. Brominated flame retardants such as 2 ″, 3 ″ -dibromoalkoxy) -3 ′, 5′-dibromophenyl) -propane, and brominated bisphenol-based flame retardants.

  Examples of brominated bisphenol-based flame retardants include, but are not limited to, tetrabromobisphenol A, tetrabromobisphenol A-bis (2,3-dibromopropyl ether), tetrabromobisphenol A-bis (2,3-dibromo). -2 methylpropyl ether), tetrabromobisphenol S, tetrabromobisphenol S-bis (2,3-dibromopropyl ether), tetrabromobisphenol S-bis (2,3-dibromo-2methylpropyl ether), tetrabromobisphenol F, tetrabromobisphenol F-bis (2,3-dibromopropyl ether), tetrabromobisphenol F-bis (2,3-dibromo-2methylpropyl ether) tetrabromobisphenol A-bis (allylate) ), Tetrabromobisphenol A polycarbonate oligomer, and an epoxy group adduct of tetrabromobisphenol A oligomers and the like. Among brominated bisphenol flame retardants, in particular, tetrabromobisphenol A bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (2,3-dibromo-2methylpropyl ether) Is preferable because it is difficult to be decomposed during kneading with a polystyrene resin and has a high flame-retardant effect and tends to be expressed easily. When tetrabromobisphenol A-bis (2,3-dibromopropyl ether) and tetrabromobisphenol A-bis (2,3-dibromo-2methylpropyl ether) are used in combination, flame retardancy and thermal stability are improved. It is more preferable because it tends to be excellent.

  When using a brominated flame retardant, it is preferable to use a brominated isocyanurate-based flame retardant as a flame retardant aid. Examples of brominated isocyanurate flame retardants include, but are not limited to, mono (2,3-dibromopropyl) isocyanurate, di (2,3-dibromopropyl) isocyanurate, and tris (2,3-dibromo). Propyl) isocyanurate, mono (2,3,4-tribromobutyl) isocyanurate, di (2,3,4-tribromobutyl) isocyanurate, tris (2,3,4-tribromobutyl) isocyanurate, etc. Is mentioned. Among brominated isocyanurates, tris (2,3-dibromopropyl) isocyanurate is particularly preferable because it exhibits a very high flame retardancy.

  The brominated flame retardant content is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the styrene resin in the styrene resin composition. It is 2 parts by mass or less and more preferably 8 parts by mass or less. When the amount is 0.1 parts by mass or more, the flame retardancy tends to be sufficiently secured, and when the amount is 10 parts by mass or less, the moldability in producing the foamed sheet tends to be sufficiently good. .

  The liquid paraffin can be selected from, for example, liquid paraffin defined by standard standards such as the Food Sanitation Law, food, and additives. Specific examples of this type of liquid paraffin include, but are not limited to, Cristol N52, Cristol N62, Cristol N72, Cristol N82, Cristol N122, Cristol N172, Crystall, commercially available from ExxonMobil. Stall N262, cristol N352, prime mall N542 and the like. Moresco White P-40, Moresco White P-55, Moresco White P-60, Moresco White P-70, Moresco White P-80, Mores, which are commercially available from Matsumura Oil Research Co., Ltd. Sco White P-85, Moresco White P-100, Moresco White P-120, Moresco White P-150, Moresco White P-200, Moresco White P-230, Moresco White P-260, Moresco White P-300, Moresco white P-350, Moresco white P-350P, etc. are mentioned. Further, liquid paraffin 40-S, 60-S, 70-S, 80-S, 90-S, 100-S, 120-S, 150-S, 260-S commercially available from Sanko Chemical Co., Ltd. 350-S. Furthermore, white mineral oil commercially available from CK Witco Corporation can be mentioned.

The molecular weight of the liquid paraffin is usually defined by kinematic viscosity. The liquid paraffin in the present embodiment, for example, a kinematic viscosity of 40 ° C. which is defined by the test method JIS K2283 is able to use a range of 0.1~60mm ² / sec, the 1~40mm ² / sec Those are preferred. Moreover, the preferable weight average molecular weight of a liquid paraffin is the range of 150-500, More preferably, it is the range of 180-450, More preferably, it is the range of 200-350. A weight average molecular weight is calculated | required by taking the weight average value of each molecular weight component of a liquid paraffin, for example using gas chromatography. When using liquid paraffin of this viscosity range or this molecular weight range, compared with liquid paraffin of higher viscosity or higher molecular weight, the resulting styrene resin composition is greatly plasticized, the moldability of the styrene resin composition, For example, the surface gloss of the molded product tends to be greatly improved. Use of liquid paraffin having a viscosity of 0.1 mm ² / sec or more or a weight average molecular weight of 150 or more effectively prevents mold contamination and bleeding on the surface of the molded product during molding of the resulting styrene resin composition. Since there exists a tendency to suppress, it is preferable.

  The content of liquid paraffin in the styrenic resin composition is preferably less than 3.0 parts by mass, more preferably less than 1.0 part by mass, and still more preferably with respect to 100 parts by mass of the styrene resin. Less than 0.5 parts by mass. When the content of the liquid paraffin is less than 5.0 parts by mass, a molded product having an excellent balance between secondary moldability, strength of the molded product, and heat resistance can be obtained.

  Moreover, in this embodiment, it is preferable to add a thermal deterioration preventing agent in the polymerization step or devolatilization step of the styrene-based resin composition, and after the polymerization step and before the devolatilization step. In particular, it is preferable to add a thermal degradation inhibitor after the polymerization step (preferably immediately after) and before the devolatilization step. By adding a thermal degradation inhibitor, radicals generated by thermal decomposition can be stabilized and the thermal decomposition amount can be reduced.

  Examples of the thermal degradation inhibitor include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (trade name: Sumilizer GM, manufactured by Sumitomo Chemical Co., Ltd.). ), 2- [1- (2-hydroxy-3,5-di-t-phenylpentyl) ethyl] -4,6-di-t-phenylpentyl acrylate (trade name: Sumilyzer GS, manufactured by Sumitomo Chemical Co., Ltd.), Phenol-based thermal degradation inhibitors such as 2,4-bis (octylthiomethyl) -6-methylphenol (trade name: Irganox 1520L) and octadecyl-3- (3,5-tertiarybutyl-4-hydroxyphenyl) propionate Hindered phenolic antioxidants such as 4,6-bis (octylthiomethyl) -o-cresol, tris (2,4-diter Phosphorus-based processing heat stabilizers such as turbocharger butylphenyl) phosphite, and the like. These thermal deterioration inhibitors may be used alone or in combination of two or more.

The content of the thermal degradation inhibitor is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0 parts per 100 parts by mass of the styrene resin in the styrene resin composition at the final reactor outlet. .3 parts by mass, more preferably 0.03 to 0.2 parts by mass.
When the content of the thermal degradation inhibitor is 0.01 parts by mass or more, it is possible to more effectively suppress the production of a monomer of a monovinyl compound and its dimer or trimer in the devolatilization step. it can. On the other hand, even if the content of the thermal degradation inhibitor is increased from 0.5 parts by mass, an effect corresponding to the content cannot be obtained.

<< Method for Producing Styrenic Resin Composition >>
The styrene resin composition of the present embodiment includes, for example, a styrene resin obtained by radical polymerization of the above monovinyl compound and a conjugated divinyl compound and / or a multibranched vinyl compound by the above production method, and the above additive. Can be obtained by a melt kneading method using a known kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer or the like. In addition, in the manufacturing process of the above-mentioned styrenic resin, you may manufacture the styrenic resin composition of this embodiment by adding the above-mentioned additive etc. suitably.

<Foam sheet>
The foam sheet of this embodiment includes the styrene resin composition of this embodiment and has a thickness of 0.5 to 5.0 mm. Moreover, it is preferable that the foamed sheet of this embodiment has an apparent density of 50 to 300 g / L and a basis weight of 80 to 300 g / m ² .
In the foam sheet of this embodiment, a film may be laminated on the sheet. As a kind of film, what is used for general polystyrene can be used.
According to the foam sheet of the present embodiment, a molded product having a good appearance can be obtained.

  For the foaming agent and foaming nucleating agent contained in the foamed sheet of this embodiment, commonly used substances can be used. Although it does not specifically limit as a foaming agent, For example, a butane, pentane, Freon, water, etc. are mentioned, A butane is suitable. Although it does not specifically limit as a foam nucleating agent, For example, a talc etc. are mentioned.

<Remaining amount of styrene monomer in foam sheet>
The residual amount of the styrene monomer in the foamed sheet of this embodiment is preferably 10 to 500 ppm by mass, more preferably 20 to 300 ppm by mass, and even more preferably 30 to 200 ppm with respect to 100% by mass of the foamed sheet. Mass ppm. When the residual amount of the styrene monomer is 10 to 500 ppm by mass, the odor of the foamed sheet can be reduced.
In the present disclosure, the residual amount of styrene monomer is a value measured using gas chromatography (GC).

<< Method for producing foam sheet >>
The manufacturing method of the foam sheet of this embodiment can be performed using the method generally known. For example, although not particularly limited, a method of melt-kneading and extruding the styrenic resin composition, the foaming agent, and the foaming nucleating agent in the present embodiment with an extruder can be mentioned, and the details are as follows.
First, the styrene resin composition in the present embodiment is melt-kneaded with an extruder connected to a circular die, and the melt-kneaded product is foamed from an annular opening provided in front of the circular die. Extrude in a state to form a cylindrical foam. Next, the foam is cooled while being stretched in the circumferential direction by sliding on the outer peripheral surface of the cooling mandrel having a diameter larger than the opening of the circular die, and is continuously cut and expanded along the extrusion direction. A commonly known method can be used.

"Molding"
The molded product in the present embodiment is a secondary molded product of the foam sheet of the present embodiment. The foamed sheet of the present embodiment is subjected to secondary molding by a conventionally known method such as vacuum molding, pressure molding, vacuum pressure molding, double-sided vacuum molding, press molding, etc., so that a tray, a cup, a straw container, a natto container, etc. The secondary molded product can be formed.
As an example of the secondary molded product of the present embodiment, the foamed sheet of the present embodiment is used as a molding material, and the vertical direction is 5.5 to 21 cm, the horizontal is 6.5 to 36 cm, and the horizontal direction is the extrusion direction by a vacuum forming machine. Examples include a food tray container having a depth of 1.1 to 3.4 cm. Although it does not specifically limit as temperature conditions of vacuum forming, Usually, 120-150 degreeC is preferable.

  As the molding method, injection molding, extrusion molding, vacuum molding, pressure molding, extrusion foam molding, calendar molding, blow molding, and the like can be suitably used, and various molded products can be obtained in a wider range of applications than before.

  Hereinafter, although an embodiment of the present invention is described concretely with an example and a comparative example, the present invention is not limited to these examples.

<< Measurement and evaluation method >>
The measurement and evaluation methods are as follows.

(1) Measurement of the number of moles of the conjugated divinyl compound relative to 1 mole of styrene The number of moles of the conjugated divinyl compound relative to 1 mole of styrene in the styrene resin composition was measured using ¹ H-NMR and ¹³ C-NMR. did. As a measuring apparatus, JEOL-ECA500 manufactured by JEOL Ltd. was used. Chloroform-d1 was used as a solvent, and the tetramethylsilane resonance line was used as an internal standard.

(2) Measurement of molecular weight The number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz), Mw / Mn, and peak top molecular weight (Mtop) of the styrene resin composition are determined by gel permeation chromatography ( GPC) was measured under the following conditions.
Device: Tosoh HLC-8220
Fractionation column: TOSGE TSK gel Super HZM-H (made by Tosoh) connected in series Guard column: TSK guard column Super HZ-H made by Tosoh
Measuring solvent: Tetrahydrofuran (THF)
Sample concentration: 5 mg of a measurement sample was dissolved in 10 mL of solvent and filtered with a 0.45 μm filter.
Injection volume: 10 μL
Measurement temperature: 40 ° C
Flow rate: 0.35 mL / min Detector: UV absorption detector (UV-8020 manufactured by Tosoh, wavelength 254 nm)
To create a calibration curve, 11 types of TSK standard polystyrenes manufactured by Tosoh (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2) F-1, A-5000). A calibration curve was prepared using an approximate expression of a linear straight line.

(3) Measurement of absolute molecular weight The absolute molecular weight of the styrene-based resin composition was measured using a multi-angle light scattering detector (MALS) under the following conditions (hereinafter sometimes referred to as “MALS method”). .
Device: Tosoh HLC-8220
Separation column: Two Kdex 806-L manufactured by Shodex connected in series Guard column: GPC KFG-4A manufactured by Shodex
Measuring solvent: Tetrahydrofuran (THF)
Sample concentration: 10 mg of a measurement sample was dissolved in 10 mL of solvent and filtered with a 0.45 μm filter.
Injection volume: 100 μL
Measurement temperature: 40 ° C
Flow rate: 1.00 mL / min Detector: Differential refractometer (RI-8022 manufactured by Tosoh Corporation)
MALS detector: Viscotek SEC-MALS 20 manufactured by Malvern
MALS detection angles: 12 °, 20 °, 28 °, 36 °, 44 ° 52 °, 60 °, 68 °, 76 °, 84 °, 90 °, 100 °, 108 °, 116 °, 124 °, 132 ° 140 °, 148 °, 156 °, 164 °
MALS detector temperature: 35 ° C
PS105K was used as a standard sample, and analysis was performed using analysis software OmniSEC5.1.
From the obtained molecular weight and the ratio of dW / dlogM, the content (%) of components having a molecular weight of 1,000,000 to 5,000,000 was calculated.

(4) Measurement of degree of branching and degree of gelation The degree of branching and the degree of gelation of the styrene resin composition were measured by the above-mentioned MALS method and calculated. A graph in which the horizontal axis is log Molecular weight and the vertical axis is log radius of migration was created. In this graph, for linear polystyrene (NBS706), a linear approximate straight line was created in the range of log Molecular weight in the range of 5.0 to 6.0, and this was calculated as the standard value of linear polystyrene having no branched structure. It was.
Here, when the log molecular weight value is 6.0 and 6.5, the value of log radius of gyrration is defined as <Rg6.0> and <Rg6.5>, respectively, and <Rg6.0>, NBS706 <Rg6.0>, <Rg6.5> is defined as <Rg6.0> _NBS and <Rg6.5> _NBS , respectively. Note that <Rg6.5> _NBS can be calculated from the extrapolated value of the approximate straight line.
The degree of branching is defined as branching degree = <Rg6.5> / <Rg6.5> _NBS . The degree of branching, the absolute molecular weight ^{106.5 = 3.16} million, it is meant whether the rotation radius with respect NBS706 a linear polystyrene becomes how smaller and the degree of branching is small, the target polymer It shows that it is branched.
The gelation degree is defined as gelation degree = (<Rg6.0> / <Rg6.0> _NBS ) / (<Rg6.5> / <Rg6.5> _NBS ). This degree of gelation represents the rate of change in the radius of rotation of the polymer from an absolute molecular weight of 10 ^6.0 to 10 ^6.5 . That is, it means how many branches are increased as the molecular weight is increased, and the larger the gelation degree, the more branches are increased as the molecular weight is increased.

(5) Measurement of melt mass flow rate (MFR) The melt mass flow rate (g / 10 min) of the styrene-based resin composition was measured according to ISO 1133 under a load condition of 200 ° C. and 49 N.

(6) Measurement of the maximum rise ratio The measurement of the maximum rise ratio of the styrene-based resin composition was performed based on the following viscoelasticity measurement.
Device name: Viscoelasticity measuring device ARES-G2 (TA Instruments)
Measurement system: ARES-EVF option Test piece dimensions: Length 20mm, thickness 0.7mm, width 10mm
Elongation strain rate: 0.01 / second Temperature: 150 ° C
Measurement atmosphere: in nitrogen stream Preheating time: 2 minutes Pre-extension strain rate: 0.03 / second,
Pre-extension length: 0.295mm
Relaxation time after pre-extension: 2 minutes For the viscoelasticity measurement, after the test piece was attached to a roller and the temperature was stabilized at the measurement temperature, the sample was left to stand for the pre-heating time and pre-heated. After completion of preheating, pre-extension was performed under the above conditions. After pre-extension, it was allowed to stand for 2 minutes, and the stress produced by the pre-extension was relaxed and measured.

From the results obtained by the above viscoelasticity measurement, a logarithmic graph in which Henkey strain is plotted on the horizontal axis and elongational viscosity is plotted on the vertical axis is created, and the range where the Henkey strain is 0.2 to 0.5 is defined as a linear region. A linear region straight line for power approximation was created (for example, a broken line in FIG. 1). When strain hardening occurs, the actual extensional viscosity becomes larger than the extensional viscosity of the approximate curve extrapolating this linear region.
The maximum rise ratio is the approximate straight line extrapolating the linear region in the maximum rising strain to the maximum rising strain, with the Henkey strain at which the extensional viscosity becomes maximum in the above viscoelasticity measurement as the maximum rising strain. Of elongation viscosity).
FIG. 1 shows a log-log graph in which the horizontal axis represents Henkey strain and the vertical axis represents elongational viscosity for the styrene copolymers obtained in Examples and Comparative Examples.

(7) Measurement of total residual amount of styrene dimer and trimer The total residual amount (mass ppm) of styrene dimer and trimer in the styrene-based resin composition was determined according to the following conditions and procedures. And measured.
Sample preparation: After dissolving 1.0 g of a styrene resin composition in 10 mL of methyl ethyl ketone, 3 mL of methanol containing a standard substance (triphenylmethane) was added to reprecipitate the polymer component, and the supernatant was collected to obtain a measurement solution. .
Measurement conditions Equipment: Agilent 6850 Series GC system Detector: FID
Column: HP-1 (100% dimethylpolysiloxane) 30 m, film thickness 0.25 μm, 0.32 mmφ
Injection volume: 1 μL (splitless)
Column temperature: held at 40 ° C. for 1 minute → heated to 320 ° C. at 20 ° C./minute→held at 320 ° C. for 10 minutes Inlet temperature: 250 ° C.
Detector temperature: 280 ° C
Carrier gas: helium

(8) Evaluation of sheet-like gel material The styrene resin composition was extruded using a 30 mmφ sheet extruder (manufactured by Soken Co., Ltd.) to prepare a sheet having a thickness of 0.5 mm. Twenty test pieces were cut out in a size of 100 mm length × 100 mm width from the obtained sheet, and a gel-like substance having an average of a short diameter and a long diameter of 2 mm or more was visually measured. Judgment was made with “◎” when the number of test pieces that contained the gel-like substance was 0-2, “◯” when 3-10, and “x” when 11 or more.

(9) Evaluation of deep drawability of sheet A styrene-based resin composition was extruded using a 30 mmφ sheet extruder (manufactured by Soken Co., Ltd.) to prepare a sheet having a thickness of 0.5 mm. Twenty test pieces were cut out in a size of 250 mm long by 250 mm wide from the obtained sheet, and the sheet was sandwiched between the fixed frames of this sheet molding machine using a Soken sheet container molding machine, and the average temperature of the heater was 220. C. and the ambient temperature were set to 110.degree. C. and heated for 20 seconds. Next, the fixed frame was slid into a mold (temperature: 40 ° C.) of a container with a diameter of 10 cm and a depth of 10 cm to perform vacuum forming, and 20 compacts were formed. Whether or not tearing had occurred on the side surface of the molded body was visually confirmed, and the number of molded bodies that could be molded without tearing was used as an index of deep drawability.

(10) Measurement of maximum moldable heating time of sheet The heating time at the time of deep drawing in (9) is extended from 20 seconds by 1 second, vacuum forming is performed without changing other conditions, Ten pieces were molded. As in (9), the heating time was extended until the number of molded bodies that could be molded was 7 or less. The maximum heating time in which 8 or more pieces could be formed was defined as the maximum forming time (seconds) in which the sheet could be formed and measured.

(11) Evaluation of appearance of molded product The gloss and rough surface of the deep-drawn molded product molded in the above (10) were visually confirmed. Of the 100 molded products, a molded product in which spots such as dripping or non-uniform surfaces are not confirmed is determined to be a molded product having a good appearance, and the number is used as an index for evaluating the appearance of the molded product. did.

(12) Measurement of residual amount of styrene monomer in foam sheet The residual amount (mass ppm) of the styrene monomer in the foam sheet was measured by a gas chromatography method under the following measurement conditions. 1 g of the foamed sheet was dissolved in 25 mL of dimethylformamide to prepare a measurement sample.
Measurement condition detection method: FID
Equipment: Shimadzu Corporation GC14B
Column: CHROMAPACK CP WAX 52CB
100m, film thickness 2μm, 0.52mmφ
Column temperature: held at 110 ° C. for 10 minutes, heated to 130 ° C. at 15 ° C./min, and held at 130 ° C. for 2 minutes.
Inlet temperature: 150 ° C
Detector temperature: 150 ° C
Carrier gas: Helium

(13) Evaluation of Deep-drawing Formability of Foamed Sheet The foamed sheet was left at 23 ± 3 ° C. and relative humidity 50 ± 5% for 20 days. Thereafter, using a sheet container molding machine manufactured by Souken, the foamed sheet was sandwiched between the fixed frames of the sheet molding machine, the heater was set at an average temperature of 200 ° C., the ambient temperature was set at 130 ° C., and heated for 15 seconds. Next, the fixed frame was slid into a cup-shaped mold (temperature: 40 ° C.) having a diameter of 10 cm and a depth of 3 cm or 6 cm, and vacuum forming was performed to form 100 compacts. Whether or not tearing had occurred on the side surface of the molded body was visually confirmed, and the number of molded bodies that could be molded without tearing was used as an index of deep drawability.

(14) Measurement of maximum moldable heating time of foam sheet During the deep drawing of (13) above, the heating time is increased from 15 seconds to 1 second, and vacuum forming is performed without changing other conditions. Ten bodies were molded. As in (13), the heating time was extended until the number of foamed sheets that could be molded was 7 or less. The maximum heating time during which it was possible to form 8 or more molded bodies was defined as the maximum moldable heating time (seconds) of the foamed sheet and measured.

(15) Foaming ratio of foam sheet The foaming ratio (times) of the foam sheet was calculated from the following formula using the foam density value (ρf) and the density (ρ) of the styrene-based resin composition.
Foaming ratio = ρ / ρf
The foam density was determined by measuring the foam density of the foam sheet based on ISO10350. As a measuring device, a hydrometer (SGM-220-60 measuring instrument) manufactured by Shimadzu Corporation was used.

"material"
In the examples and comparative examples, the following materials were used.

<Styrene resin>
<Monovinyl compound>
Styrene: Styrene monomer [Asahi Kasei Co., Ltd.]

<Conjugated divinyl compound>
<Conjugated divinyl compound 1>
The conjugated divinyl compound 1 was produced based on the following method.
In a 5 L reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 2742 g of polybutadiene alcohol at both ends (Mn: 1900), 379 g of methyl acrylate, 380 g of n-hexane, 0.8194 g of hydroquinone monomethyl ether, and 4 -0.5533 g of hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl was charged. While passing the obtained mixture through a calcium chloride tube, air was blown into the mixture, and reflux dehydration was performed at 80 to 85 ° C. The moisture contained in this mixture was measured by the Karl Fischer method, and it was confirmed that the water content was 200 ppm or less. Thereafter, 1.36885 g of tetra-n-butyl titanate was added to the above mixture as a transesterification catalyst, and the resulting methanol was stirred out while distilling out of the reaction system under reflux of n-hexane, an azeotropic solvent. And reacted at a reaction temperature of 80 to 85 ° C. for 10 hours.
Next, the temperature in the reaction vessel is adjusted to 75 to 80 ° C., and concentrated at a reduced pressure of 70 to 2 kPa until 95% or more of the used methyl acrylate and n-hexane are distilled off. n-Hexane was recovered. To 2070 g of the obtained polybutadiene both-end diacrylate, 2000 g of toluene, 200 g of acetone, 20 g of ion-exchanged water, and hydrotalcite (composition formula Mg ₆ Al ₂ (OH) 16 CO ₃ .4H ₂ O) [Kyowa Chemical Co., Ltd.] Industrial Co., Ltd., trade name: KYOWARD 500PL] 20 g was added and treated at 75-80 ° C. for 2 hours. Next, by adjusting the temperature in the reaction vessel to 75 to 80 ° C. and concentrating at a reduced pressure of 90 to 35 kPa, 400 g of a mixed distillate of toluene, acetone and water is recovered, and the resulting concentrated solution is air. The catalyst and the adsorbent were separated by filtration under pressure, and the solvent was degassed at a temperature of 60 to 80 ° C. and a degree of vacuum of 30 to 0.8 kPa to obtain a conjugated divinyl compound 1.
It was 99.3% when the conversion rate of the polybutadiene both terminal diacrylate of the conjugated divinyl compound 1 was measured by high performance liquid chromatography (HPLC). The number average molecular weight (Mn) in terms of polystyrene measured by GPC was 1900.

Conjugated divinyl compound 2: polybutadiene diacrylate [manufactured by Sakai Kogyo Co., Ltd .: CN307] Mn: 3800
Conjugated divinyl compound 3: polybutadiene-terminated acrylate [manufactured by Osaka Organic Chemical Industry: BAC-45] Mn: 4800
Conjugated divinyl compound 4: urethane acrylate oligomer [manufactured by Sakai Kogyo Co., Ltd .: CN9014NS] Mn: 8000

<Conjugated divinyl compound 5>
The conjugated divinyl compound 5 was produced based on the following method.
The conjugated divinyl compound 5 produced under the same conditions as in the case of the conjugated divinyl compound 1 except that the molecular weight of the polybutadiene alcohol at both ends was changed to Mn: 25000 had a conversion rate of 99.5% of the polybutadiene both ends diacrylate. It was. Moreover, the number average molecular weight (Mn) of polystyrene conversion measured by GPC was 26000.

<Conjugated divinyl compound 6>
The conjugated divinyl compound 6 was produced based on the following method.
The conjugated divinyl compound 6 produced under the same conditions as in the case of the conjugated divinyl compound 1 except that the molecular weight of the polybutadiene alcohol at both ends was changed to Mn: 57000 had a conversion rate of polybutadiene diterminal diacrylate of 99.2%. It was. The number average molecular weight (Mn) in terms of polystyrene measured by GPC was 58,000.

Conjugated divinyl compound 7: aromatic urethane acrylate [manufactured by Sakai Kogyo Co., Ltd .: CN9782] Mn: 5200
Conjugated divinyl compound 8: 1,3-butylenediol dimethacrylate [manufactured by Wako Pure Chemical Industries, Ltd.] Molecular weight: 226
Conjugated divinyl compound 9: NK ester A-GLY-20E [manufactured by Shin-Nakamura Chemical Co., Ltd.] Molecular weight: 1295, the average number of conjugated vinyls in one molecule of conjugated divinyl compound 9 is 3.
Conjugated divinyl compound 10: Divinylbenzene [Wako Pure Chemical Industries, Ltd.] Molecular weight: 130

<Multi-branched vinyl compound>
<Multi-branched vinyl compound 1>
3.1 mol (399.4 g) of divinylbenzene, 0.7 mol (95.1 g) of ethylvinylbenzene, 0.3 mol (31.6 g) of styrene, 2.3 mol (463.5 g) of 2-phenoxyethyl methacrylate Then, 974.3 g of toluene was put into a 3.0 L reactor, 42.6 g of boron trifluoride diethyl ether complex was added at 50 ° C., and reacted for 6.5 hours. After stopping the polymerization reaction with a sodium hydrogen carbonate solution, the oil layer was washed three times with pure water, and the reaction mixture was poured into a large amount of methanol at room temperature to precipitate a polymer. The obtained polymer was washed with methanol, filtered, dried and weighed to obtain 372.5 g of a multi-branched vinyl compound 1.
This multi-branched vinyl compound 1 has a weight average molecular weight (Mw) of 8000, a molar fraction of the structural unit (a1) containing a vinyl group derived from a divinyl compound is 0.44, and a two-phenoxyethyl methacrylate derived from the terminal 2-phenoxyethyl methacrylate. The double bond (a2) was 0.03, and the combined molar fraction (a3) of both was 0.47. Further, the inertial radius of the polymer at a weight average molecular weight (Mw) of 8000 was 6.3 nm. The ratio of the radius of inertia of the polymer to the molar fraction of the double bond is 13.4, and the ratio of the radius of inertia at a linear weight average molecular weight (Mw) of 8000 is 15 nm. It can be seen that the multi-branched vinyl compound 1 in the synthesis example has a branched structure.

<Multi-branched vinyl compound 2>
In a 2 liter flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser, 50.5 g of ethoxylated pentaerythritol (ethylene oxide-added pentaerythritol) disclosed in JP-A-2016-113598, BF ₃ diethyl ether at room temperature 1 g of solution (50%) was added and heated to 110 ° 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.
In a reactor equipped with a stirrer, a thermometer, a Dean-Stark decanter equipped with a condenser and a gas introduction tube, 50 g of the multi-branched polyether polyol obtained above, 13.8 g of methacrylic acid, 150 g of toluene, 0.06 g of hydroquinone, para 1 g of toluenesulfonic acid was added, and the mixture was stirred and heated under normal pressure while blowing 7% oxygen-containing nitrogen (v / v) at a rate of 3 mL / min into the mixed solution. 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, and the solvent was distilled off while introducing 7% oxygen-containing nitrogen (v / v) under reduced pressure to obtain a multibranched vinyl compound 2 having an isopropenyl group and an acetyl group 60 g was obtained. The resulting multi-branched vinyl compound 2 has a weight average molecular weight of 3,900, and the introduction rate of isopropenyl group and acetyl group into the multi-branched polyether polyol is 30 mol% and 62 mol%, respectively, based on the total hydroxyl groups. Met.

<Additive>
Thermal degradation inhibitor 1: 2- [1- (2-hydroxy-3,5-di-t-phenylpentyl) ethyl] -4,6-di-t-phenylpentyl acrylate [Sumitomo Chemical Co., Ltd .: Sumilyzer GS ]

<Others>
Polymerization initiator 1: 2,2-bis (4,4-di-tertiary-butylperoxycyclohexyl) propane [manufactured by NOF Corporation: Pertetra A]
Polymerization initiator 2: 1,1-di- (tertiary-butylperoxy) cyclohexane [manufactured by NOF Corporation: Perhexa C]
Chain transfer agent 1: α-methylstyrene dimer [Nippon Yushi Co., Ltd .: NOFMER MSD]
Foam nucleating agent: Talc (Matsumura Sangyo Co., Ltd., product name “High Filler # 12”)
Foaming agent: Isobutane: made by Mitsui Chemicals

<Example 1>
80 parts by mass of styrene monomer, 20 parts by mass of ethylbenzene, 0.031 parts by mass of conjugated divinyl compound 1 obtained by the above production method (2.1 × 10 ⁻⁵ mol per 1 mol of styrene), polymerization started 0.025 parts by mass of Agent 1 was added to prepare a raw material solution to be supplied to the first reactor. The prepared raw material solution was continuously supplied at 0.6 L / hour to a fully mixed first reactor having an internal volume of 5.4 L maintained at a temperature of 102 ° C.
Next, 80 parts by mass of styrene monomer, 20 parts by mass of ethylbenzene, 0.35 parts by mass of chain transfer agent 1 and 0.023 parts by mass of polymerization initiator 2 are added, and the raw material solution supplied to the second reactor Adjusted. The prepared raw material solution was added to a plug flow type second reactor having an internal volume of 1.5 L in which the temperature of the three zones was maintained at 122, 127, and 115 ° C. in the order in which the raw material solution passed, and 0.17 L / hour. Continuously fed.
Next, the polymerization solutions from the first reactor and the second reactor were joined, and the temperature of the four zones was maintained at 126, 139, 140, and 140 ° C. in the order in which the raw material solutions passed through. It was fed to a plug flow type third reactor. In zone 1 of the third reactor, 0.03 parts by mass of polymerization initiator 2 was added. Further, in zone 3 of the third reactor, 0.1 part by mass of thermal degradation inhibitor 1 was added.
Next, the polymerization solution from the third reactor was supplied to a vacuum degassing tank heated to a temperature of 240 ° C., volatile components such as unreacted monomers and solvents were removed, and evaluation was performed after 72 hours of continuous operation. A styrene resin composition for use was obtained.
With respect to 100 parts by mass of the styrenic resin composition, 0.15 parts by mass of talc (average particle size 1.3 μm) as a foam nucleating agent and 4 parts by mass of liquefied butane as a foaming agent are added to obtain a foam sheet raw material. Obtained. Using an extrusion foaming machine equipped with a circular die having a diameter of 150 mm, the foamed sheet material was extruded and foam-molded. The temperature of the resin melting zone of the extrusion foaming machine was adjusted to 200 to 230 ° C, the rotary cooler temperature to 130 to 170 ° C, and the die temperature to 135 to 155 ° C. The foam immediately after extrusion foaming was cooled with a cooling mandrel and cut with a cutter at one point on the circumference to obtain a foamed sheet having a thickness of 1.4 mm and a width of 1000 mm.
The production conditions and analysis results of Example 1 are shown in Table 1.

<Examples 2 to 13>
Examples 2 to 13 were carried out in the same manner as in Example 1 except that the conditions were changed as shown in Table 1, and a styrene resin composition and a foamed sheet were obtained.
Table 1 summarizes the measurement and evaluation results of Examples 2 to 13.
In addition, as shown in FIG. 1, in the styrene resin composition of Example 4, it turns out that distortion hardening was expressed in the measurement of ARES-EVF.

<Comparative Examples 1-6>
Comparative Examples 1 to 6 were carried out in the same manner as in Example 1 except that the conditions were changed as shown in Table 1 to obtain a styrene resin composition and a foamed sheet.
The measurement and evaluation results of Comparative Examples 1 to 6 are summarized in Table 1.

  As is apparent from Table 1, Comparative Example 1 having a small Mw / Mn of 2.8 and a high degree of branching of 0.95 and a large Mtop of 276,000 have a component with an absolute molecular weight of 1 million to 5 million. In Comparative Example 2 where the amount was as low as 9.3%, the maximum rise ratios as measured by ARES-EVF were all 1.00, and strain hardening did not occur. Further, Comparative Examples 3, 5, and 6 having high gelation degrees of 1.56, 1.29, and 1.34, respectively, had a large amount of gel-like material in the sheet. In Comparative Example 4 having a high branching degree of 0.97, the maximum moldable heating time was short and the molding condition width was narrow.

On the other hand, the degree of branching is 0.70 to 0.94,
The degree of gelation is 1.00 to 1.25,
The content of components having an absolute molecular weight of 1,000,000 to 5,000,000 measured using a multi-angle light scattering detector (MALS) is 10.0 to 15.0%,
The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured using gel permeation chromatography (GPC) is 3.0 to 5.0,
The styrene-based resin composition of Examples 1 to 13 having a peak top molecular weight (Mtop) measured using GPC of 100,000 to 180,000 has few gel-like substances on the sheet, and has appropriate characteristics. It can be seen that the molding processability is excellent and the molding condition width is wide.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this, and can be appropriately changed without departing from the spirit of the invention.

  The styrenic resin composition according to the present invention is excellent in molding processability, has a wide range of molding conditions, and has a small amount of gel substance. For example, as a molding material or food packaging material for home appliances, office machine products, miscellaneous goods, house equipment, Can be widely used.

Claims (6)

The degree of branching is 0.70 to 0.94,
The degree of gelation is 1.00 to 1.25,
The content of components having an absolute molecular weight of 1,000,000 to 5,000,000 measured using a multi-angle light scattering detector (MALS) is 10.0 to 15.0%,
The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured using gel permeation chromatography (GPC) is 3.0 to 5.0,
A styrene resin composition having a peak top molecular weight (Mtop) measured by GPC of 100,000 to 180,000.   The styrenic resin composition according to claim 1, wherein the maximum rise ratio is 1.2 to 5.0.   The styrene resin composition according to claim 1 or 2, wherein a total residual amount of styrene dimer and trimer is 0.01 to 0.30 mass% with respect to 100 mass% of the styrene resin composition. object.   A foamed sheet comprising the styrenic resin composition according to any one of claims 1 to 3 and having a thickness of 0.5 to 5.0 mm.   A molded article comprising the foamed sheet according to claim 4.   The method for producing a styrenic resin composition according to any one of claims 1 to 3, wherein continuous solution polymerization or continuous bulk polymerization is used.