Method for producing styrene resin, styrene resin and molded article

Abstract

This invention provides a method for producing styrene-based resins that can contribute to reducing the carbon footprint. [Solution] According to the present invention, a method for producing a styrene resin is provided, comprising a polymerization step, wherein in the polymerization step, a raw material monomer containing a styrene monomer (B) is polymerized, and the styrene monomer (B) has a sustainable ratio of 0.1 to 100% assigned using a mass balance method.

Description

Technical Field

[0001] The present invention relates to a method for producing a styrene resin, a styrene resin, and a molded article.

Background Art

[0002] While plastic products are an indispensable material in society, the generation of greenhouse gases in the life cycle from their production to disposal and recycling has become an issue. For this reason, efforts are being made to reduce the CO2 equivalent amount (carbon footprint) of greenhouse gases emitted throughout the entire life cycle from the production to the disposal and recycling of plastic products.

[0003] As a method for reducing the carbon footprint, there is a method of converting the raw material monomer of a plastic product from a monomer derived from conventional fossil fuels to a monomer derived from biomass. For example, Patent Document 1 discloses a method for producing a polyolefin using ethylene or α-olefin derived from ethanol obtained from a biomass raw material as a raw material monomer. Further, Patent Document 2 discloses a method for producing a conjugated diene copolymer obtained by polymerizing biobutadiene derived from bioethanol.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, although methods for deriving styrene monomers from biomass-derived alcohols are being actively investigated, they have not yet been industrialized. As a result, it has been difficult to manufacture styrene resins that can contribute to reducing the carbon footprint using styrene monomers derived from biomass-derived alcohols. Furthermore, deriving styrene monomers from biomass-derived alcohols requires additional processes and equipment, which makes it difficult to consider this method as a useful tool from the perspective of reducing the carbon footprint.

[0006] This invention has been made in view of the above problems and provides a method for producing a styrene-based resin that can contribute to reducing the carbon footprint. Furthermore, this invention provides a styrene-based resin that can contribute to reducing the carbon footprint, and a molded article obtained by molding a styrene-based resin composition containing the styrene-based resin. [Means for solving the problem]

[0007] The present invention provides the following: [1] A method for producing a styrene resin, comprising a polymerization step, wherein in the polymerization step, raw material monomers containing a styrene monomer (B) are polymerized, and the styrene monomer (B) has a sustainable ratio of 0.1 to 100% assigned using a mass balance method. A method for producing a styrene resin as described in [2][1], wherein the raw material monomer includes a fossil fuel-derived styrene monomer (A). A method for producing a styrene resin according to [3] [1] or [2], wherein the raw material monomer comprises monomer (C), and monomer (C) comprises at least one selected from the group consisting of (meth)acrylic acid ester monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides. A method for producing a styrene resin according to [4][2] or [3], wherein the content of the styrene monomer (B) in the raw material monomers is 0.1 to 99.9% by mass, based on 100% by mass of the total raw material monomers. A method for producing a styrene resin according to any one of [5][1] to [4], wherein in the polymerization step, biocircular styrene and / or circular styrene are used as the styrene monomer (B). [6] A styrene resin having constituent units derived from a styrene monomer, wherein the styrene monomer includes styrene monomer (B), and the sustainable ratio assigned using a mass balance method is 0.0001 to 100%. A styrene resin as described in [7][6], wherein the styrene monomer contains a fossil fuel-derived styrene monomer (A). A styrene resin according to [8][6] or [7], having constituent units derived from monomer (C), wherein monomer (C) includes at least one selected from the group consisting of (meth)acrylic acid ester monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides. A styrene-based resin described in any one of [9][6] to [8], wherein the weight-average molecular weight (Mw) is between 50,000 and 400,000. A styrene resin described in any one of

[10] [6] to [9], wherein the melt mass flow rate (MFR) measured in accordance with JIS K7210 at 200°C and a 49N load is 0.1 to 30.0 g / 10 min. A molded article obtained by molding a styrene resin composition containing a styrene resin described in any one of

[11] [6] to

[10] .

[0008] Through diligent research, the inventors discovered that the above problems can be solved in the production of styrene-based resins by using styrene-based monomers derived from fossil fuels and styrene-based monomers whose sustainable ratio, allocated using a mass balance method, is equal to or greater than a predetermined amount, as raw material monomers, thus completing the present invention. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature can stand alone as an independent invention.

[0010] <Styrene resin> The styrene-based resin of the present invention is a polymer obtained by polymerizing a raw material monomer containing at least a styrene-based monomer (B). The raw material monomer may contain a fossil fuel-derived styrene-based monomer (A), and may further contain a monomer (C) copolymerizable with these styrene-based monomers. That is, the styrene-based resin of the present invention may be a copolymer having constituent units derived from styrene-based monomers and constituent units derived from monomer (C). Furthermore, the styrene-based resin of the present invention may be a copolymer having constituent units derived from monomers other than monomers (A), (B), and (C).

[0011] Fossil fuel-derived styrene monomers (A) are styrene monomers obtained from raw materials such as petroleum, coal, natural gas, and shale gas, which are formed when the remains of plants and animals are decomposed under pressure over hundreds of millions of years by soil and geothermal heat, liquefying and then turning into gas. 14 Since a sufficient amount of time has elapsed compared to the half-life of the 1C isotope (5700 years), in the elemental analysis of fossil fuel-derived styrene monomers (A), 14 C is not detected. In this invention, the fossil fuel-derived styrene monomer (A) is a non-sustainable monomer and does not contain sustainable monomers such as circular styrene described later.

[0012] Styrene monomer (B) is a styrene monomer having a sustainable ratio assigned using a mass balance method. The mass balance method is a technique in which, when raw materials with different properties are mixed, the properties of a certain raw material are arbitrarily assigned to a portion of the product to be produced according to the amount of that raw material input. In this invention, styrene monomer (B) is a monomer produced by mixing sustainable raw materials and fossil fuel-derived raw materials using conventional equipment and manufacturing methods, and has an arbitrary sustainable ratio assigned according to the amount of sustainable raw materials input.

[0013] For example, if 40 parts by mass of biomass-derived sustainable raw materials and 60 parts by mass of fossil fuel-derived raw materials are used to produce 10 products of styrene monomer (B) with a biomass component content of approximately 40% by mass, the actual biomass component content is approximately 40% by mass in all products. However, the sustainable ratio of any four of the 10 products can be set to 100%, and the sustainable ratio of the remaining six can be set to 0%. Thus, the sustainable ratio can differ from the actual biomass component content in individual products and is an indicator of the contribution of each product to reducing the carbon footprint of the entire industry. The sustainable ratio can be arbitrarily assigned to individual products within a range corresponding to the amount of sustainable raw materials used, and is not limited to 0% or 100% as described above. In one embodiment, the sustainable ratio of styrene monomer (B) is preferably 0.1 to 100%, more preferably 1 to 100%, and even more preferably 10 to 100%. This sustainability ratio can be, for example, 0.1, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100%, and may also be within the range of any two of the values ​​exemplified here. If the sustainability ratio is too low, the contribution to reducing the carbon footprint of the industry as a whole will be insufficient.

[0014] Examples of sustainable raw materials include unused biomass such as corn, sugarcane, rapeseed, sunflower, palm, soybean, rice, wheat, willow, and poplar; biomass-derived waste and residues such as rice straw, wheat straw, thinned wood, oil extraction residue, tall oil, UC oil, and food waste; and non-biomass-derived materials such as recyclable plastics. In this specification, "biomass-derived sustainable raw materials" include unused biomass and biomass-derived waste and residues. The carbon content in biomass-derived sustainable raw materials is 14 It contains a certain amount of 13C isotope.

[0015] In this specification, styrene monomers (B) produced using unused biomass, biomass-derived waste or residues, and recyclable non-biomass-derived materials are defined as biostyrene, biocircular styrene, and circular styrene, respectively. In the present invention, styrene monomers (B) may be any of these, but from the viewpoint of avoiding food competition, ensuring stable procurement, and effectively utilizing waste materials, non-edible biocircular styrene and / or circular styrene are preferred.

[0016] It is preferable that the styrene monomer (B) is manufactured by a supplier that has obtained international certifications related to sustainability and carbon, such as ISCC EU certification or ISCC PLUS certification. In this case, the traceability of the styrene monomer (B) is guaranteed, and the carbon footprint reduction effect of using the styrene monomer (B) becomes clearer.

[0017] For example, in ISCC PLUS certification, the traceability is guaranteed by the continuity of evidence storage that combines the certification of the manufacturing site and the certification of raw materials, that is, the chain of custody (CoC). It must be possible to identify where the raw materials originated and how they were recovered, processed, transported, and recycled after generation. Therefore, suppliers of styrene monomers (B) that have obtained ISCC PLUS certification can issue and attach a sustainability declaration (SD), which is a document regarding the details of raw materials, for each product delivery and pass it on to downstream users. This enables the management of the movement and information of monomers as a set in the production of styrene resins, ensuring traceability. In the production of styrene resins, after receiving the SD, it is preferable to confirm that the supplier of styrene monomer (B) holds a valid certification at the time of SD issuance.

[0018] Examples of styrene monomers containing fossil fuel-derived styrene monomer (A) and styrene monomer (B) include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, ethylstyrene, p-t-butylstyrene, α-methylvinyltoluene, dimethylstyrene, bromostyrene, dibromostyrene, etc. These can be used alone or in combination of two or more. In one embodiment, it is preferable to use styrene as the styrene monomer.

[0019] The monomer (C) preferably contains at least one selected from the group consisting of (meth)acrylate-based monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides. The content of the structural unit derived from the monomer (C) in the styrene resin is not particularly limited, but in one embodiment, it can be 1 to 99% by mass based on 100% by mass of the styrene resin. Specifically, this content can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99% by mass, and it may also be within the range between any two of the values exemplified herein.

[0020] Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, benzyl (meth)acrylate; (meth)acrylic acid cycloalkyl esters such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecanyl (meth)acrylate, adamantyl (meth)acrylate; glycidyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, etc. These can be used alone or in combination of two or more. In one embodiment, the (meth)acrylic acid ester monomer is preferably a (meth)acrylic acid alkyl ester, more preferably methyl methacrylate.

[0021] Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, etc. These can be used alone or in combination of two or more. In one embodiment, the vinyl cyanide monomer is preferably acrylonitrile.

[0022] Examples of α,β-ethylenically unsaturated carboxylic acids include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; dicarboxylic acids such as maleic anhydride, fumaric acid, and itaconic anhydride, and their anhydrides; and monoalkyl esters of dicarboxylic acids such as monomethyl malate, monoethyl malate, monobutyl malate, mono-2-ethylhexyl malate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, mono-2-ethylhexyl fumarate, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, and mono-2-ethylhexyl itaconate. These can be used individually or in combination of two or more. In one embodiment, the α,β-ethylenically unsaturated carboxylic acids are preferably methacrylic acid and maleic anhydride.

[0023] Examples of imides include maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-pentylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-isopropylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-butylmaleimide, N-cyclopropylmaleimide, N-cyclobutylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide. These can be used individually or in combination of two or more. In one embodiment, the imide is preferably N-phenylmaleimide.

[0024] In one embodiment, the raw material monomer of the styrene-based resin preferably contains a (meth)acrylic acid ester monomer as monomer (C). The styrene-based resin is preferably a copolymer containing 5 to 95% by mass of constituent units derived from styrene-based monomers and 5 to 95% by mass of constituent units derived from (meth)acrylic acid ester monomers, more preferably a copolymer containing 10 to 90% by mass of constituent units derived from styrene-based monomers and 10 to 90% by mass of constituent units derived from (meth)acrylic acid ester monomers, even more preferably a copolymer containing 15 to 85% by mass of constituent units derived from styrene-based monomers and 15 to 85% by mass of constituent units derived from (meth)acrylic acid ester monomers, and particularly preferably a copolymer containing 20 to 65% by mass of constituent units derived from styrene-based monomers and 35 to 80% by mass of constituent units derived from (meth)acrylic acid ester monomers. The content of constituent units derived from styrene monomers is specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 95% by mass, and may be within the range of any two of the values ​​exemplified here. Similarly, the content of constituent units derived from (meth)acrylic acid ester monomers is specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, and 95% by mass, and may be within the range of any two of the values ​​exemplified here. By setting the content of constituent units derived from styrene monomers and (meth)acrylic acid ester monomers within these ranges, it is possible to achieve excellent hue and transmittance while suppressing costs and reducing the carbon footprint.

[0025] The weight-average molecular weight (Mw) of the styrene resin is preferably 50,000 to 400,000, more preferably 100,000 to 350,000, specifically for example 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, and 400,000, and may be within the range of any two of the values ​​exemplified here. Furthermore, the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) (Mw / Mn) of the styrene resin is preferably 1.0 to 3.5, more preferably 1.5 to 3.0, specifically for example 1.0, 1.5, 2.0, 2.5, 3.0, and may be within the range of any two of the values ​​exemplified here. By setting the weight-average molecular weight (Mw) of the styrene resin and the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) (Mw / Mn) within such ranges, it is possible to achieve both strength and moldability of the molded article when molding the styrene resin. If the weight-average molecular weight (Mw) is too low, the strength of the molded article tends to be insufficient, and if it is too high, the moldability may decrease. Similarly, if the ratio of number-average molecular weights (Mn) (Mw / Mn) is too low, the moldability tends to decrease, and if it is too high, the strength of the molded article may decrease. The weight-average molecular weight (Mw) can be measured by gel permeation chromatography (GPC), as described in the following examples.

[0026] The styrene resin of the present invention can be widely used in home appliance components, light guide plates and diffusers for liquid crystal display panels, food packaging containers, etc. However, when used for molding optical products such as light guide plates, the polymerization inhibitor content is preferably 0 to 10 ppm. Here, ppm refers to the concentration on a mass basis relative to the total amount of raw material monomers. The polymerization inhibitor may be contained in the raw material monomers of the styrene resin, and specifically, examples include t-butylcatechol (TBC) and 6-tert-butyl-2,4-xylenol (TBX). In one embodiment, the polymerization inhibitor is preferably TBC and / or TBX. The TBC content in the styrene resin is preferably 0 to 10 ppm, and more preferably 0 to 5 ppm. The TBC content is specifically, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 ppm, and may also be within the range of any two of the values ​​exemplified here.

[0027] Furthermore, the TBX content in the styrene resin is preferably 0 to 10 ppm, and more preferably 0 to 5 ppm. Specifically, the TBX content is, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 ppm, and may be within the range of any two of the values ​​exemplified here. By setting the TBC and TBX content within such ranges, a styrene resin with excellent hue and transmittance can be obtained. The TBC and TBX content can be measured by gas chromatography-mass spectrometry (GC / MS), as described in the following examples.

[0028] The melt mass flow rate (MFR) of styrene resins can be measured according to JIS K 7210. Under conditions of 200°C and a 49N load, as measured according to JIS K 7210, the MFR is preferably 0.1 to 30.0 g / 10 min, and more preferably 0.2 to 25.0 g / 10 min. Specifically, this MFR can be, for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 g / 10 min, and may also be within the range of any two of the values ​​exemplified here. If the MFR is too low, molding stability tends to decrease, and if the MFR is too high, the strength of the molded article tends to be insufficient.

[0029] <Styrene-based resin composition> The styrene-based resin composition of the present invention contains at least the styrene-based resin of the present invention and may contain one or more of the following: a phenolic antioxidant, a phosphorus-based antioxidant, and a phosphorus-phenolic antioxidant, to the extent that the properties of the present invention are not impaired.

[0030] Phenolic antioxidants are antioxidants that have a phenolic hydroxyl group in their basic structure and are not (phosphorus) esters. Examples of phenolic antioxidants include octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 4,6-bis(octylthiomethyl)-o-cresol, and hexa Methylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-m-cresol), 3,9-bis[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1 ,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)hexahydro-1,3,5-triazine-2,4,6-trione, 2,6-di-tert-butyl-4-(4, Examples include 6-bis(octylthio)-1,3,5-triazine-2-ylamine)phenol, 4,4'-thiobis(6-tert-butyl-3-methylphenol), 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, and 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate. These can be used individually or in combination of two or more.

[0031] Phosphorus-based antioxidants are (phosphorus) esters that do not have a phenolic hydroxyl group in their basic skeleton, and are preferably trivalent phosphorus compounds. Specific examples of phosphorus-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, and 2,2' Examples include methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, tris[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphephine-6-yl]oxy]ethyl]amine, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphorous acid, tetrakis(2,4-di-tert-butylphenyl)(1,1-biphenyl)-4,4'diylbisphosphonite, tris(nonylphenyl)phosphite, etc., which can be used individually or in combination of two or more.

[0032] Phosphorus-phenol antioxidants are ()phosphorus esters having a phenolic hydroxyl group in their basic skeleton, and preferably trivalent phosphorus compounds having a phenolic hydroxyl group in their basic skeleton. Examples of phosphorus-phenol antioxidants include 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepine.

[0033] Furthermore, the styrene-based resin composition of the present invention may also contain release agents such as sulfur-based antioxidants, lactone-based antioxidants, hindered amine-based light stabilizers, ultraviolet absorbers, antistatic agents, hydrophilic additives, liquid paraffin (mineral oil), polyethylene wax, microcrystalline wax, bluing agents, higher fatty acids such as lauric acid, myristic acid, palmitic acid, and stearic acid, higher fatty acid amides such as stearic acid amide, erucic acid amide, and ethylenebisstearic acid amide, higher fatty acid glycerides such as lauric acid monoglyceride, palmitic acid monoglyceride, stearic acid monoglyceride, and behenic acid monoglyceride, and higher alcohols such as myristyl alcohol, cetyl alcohol, and stearyl alcohol, to the extent that they do not impair the properties of the present invention.

[0034] <Method for manufacturing styrene-based resins> A method for producing a styrene-based resin according to one embodiment includes a polymerization step. In the polymerization step, raw material monomers including a styrene-based monomer (B) are polymerized. The styrene-based monomer (B) has a sustainable ratio of 0.1 to 100% assigned using a mass balance method. The styrene-based monomer (B) is preferably non-edible biocircular styrene and / or circular styrene.

[0035] The raw material monomers used in the polymerization process may include fossil fuel-derived styrene monomers (A), and may also include monomers (C) copolymerizable with styrene monomers. Monomer (C) preferably includes at least one selected from the group consisting of (meth)acrylic acid ester monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides.

[0036] Known styrene polymerization methods for polymerizing styrene resins in the polymerization process include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. In terms of quality and productivity, bulk polymerization and solution polymerization are preferred, and continuous polymerization is preferable. Examples of solvents that can be used 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.

[0037] During the polymerization of styrene-based resins, polymerization initiators, chain transfer agents, crosslinking agents, and other polymerization aids can be used as needed. Radical polymerization initiators are preferred as polymerization initiators, and known and commonly used ones include peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2,2-di(4,4-di-t-butylperoxycyclohexyl)propane, and 1,1-di(t-amylperoxy)cyclohexane; hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide; alkyl peroxides such as t-butylperoxyacetate and t-amylperoxyisononanoate; and t-butylcumylperoxide, di-t-butylperoxide, dicumylperoxide, and di-t-hexylperoxide. Examples include dialkyl peroxides such as t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl monocarbonate, peroxyesters such as t-butyl peroxyisopropyl carbonate, polyethertetrakis(t-butyl peroxycarbonate), N,N'-azobis(cyclohexane-1-carbonitride), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile), N,N'-azobis[2-(hydroxymethyl)propionitrile], and these can be used individually or in combination of two or more. Examples of chain transfer agents include aliphatic mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, aromatic mercaptans, thiocarboxylic acids such as thioglycolic acid and mercaptopropionic acid, polyfunctional mercaptans obtained by esterifying the hydroxyl group of polyhydric alcohols such as ethylene glycol, tetraethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol with thioglycolic acid or mercaptopropionic acid, pentaphenylethane, α-methylstyrene dimer, and terpinolene.Among these, aliphatic mercaptans, aromatic mercaptans, thiocarboxylic acids, and polyfunctional mercaptans are preferred due to their ease of molecular weight adjustment.

[0038] In the case of continuous polymerization, styrene-based resins can be manufactured by a method comprising a polymerization step, a defoliation step, and a granulation step.

[0039] First, in the polymerization process, known fully mixed stirring tanks or tower reactors are used to control the polymerization reaction by adjusting the polymerization temperature and other means to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate.

[0040] The polymerization solution containing the polymer that has exited the polymerization process is transferred to the defoliation process, where unreacted monomers and polymerization solvent are removed. The defoliation process consists of a vacuum defoliation tank with a heater or a defoliation extruder with a vent. The molten polymer that has exited the defoliation process is transferred to the granulation process. In the granulation process, the molten resin is extruded in strand form from a porous die and processed into pellets using a cold-cut method, an air-hot-cut method, or an underwater-hot-cut method.

[0041] The TBC and TBX content in the styrene resin can be adjusted at the start of polymerization of the styrene resin and during subsequent defoliation steps.

[0042] From the viewpoint of reducing carbon footprint and costs, the content of styrene monomer (B) relative to 100% by mass of the total raw material monomers used in the polymerization process is preferably 0.1 to 100% by mass. If the raw material monomers include monomers other than styrene monomer (B), the content of styrene monomer (B) is preferably 0.1 to 99.9% by mass, more preferably 1 to 99% by mass, and even more preferably 10 to 90% by mass. Specifically, for example, these are 0.1, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 99.9% by mass, and may be within the range of any two of the values ​​exemplified here.

[0043] From a traceability standpoint, it is preferable to manufacture styrene resins using styrene monomers (B) produced by suppliers that have obtained international certifications related to sustainability and carbon, such as ISCC EU certification or ISCC PLUS certification. Furthermore, it is preferable to use styrene monomers (B) only after confirming that the supplier of styrene monomers (B) holds a valid certification at the time of SD issuance.

[0044] In the production of styrene-based resins, a styrene monomer (B) having a sustainable ratio assigned using a mass balance method is used. Therefore, the sustainable ratio can also be assigned to the styrene-based resin produced by the above method using a mass balance method. The sustainable ratio of the styrene-based resin according to the present invention is defined by the following formula. Sustainability ratio of styrene resin (%) = Sustainability ratio of styrene monomer (B) (%) × Content of styrene monomer (B) relative to 100% by mass of total raw material monomers used in the polymerization process (by mass) / 100

[0045] If the monomers other than the styrene monomer (B) contained in the raw material monomer have a sustainable ratio, the sustainable ratio (%) of the styrene resin can be calculated as the sum of the sustainable ratio (%) of each monomer × the content (mass%) of each monomer / 100.

[0046] In one embodiment, the sustainable ratio of the styrene resin is preferably 0.0001 to 100%, more preferably 0.0001 to 99.9%, even more preferably 0.001 to 99%, and particularly preferably 0.01 to 90%. Specifically, the sustainable ratio of the styrene resin is, for example, 0.0001, 0.001, 0.01, 0.1, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99, 99.9, and 100%, and may be within the range of any two of the values ​​exemplified here. By setting the sustainable ratio of the styrene resin within such a range, it is possible to contribute to reducing the carbon footprint of the entire industry while suppressing costs.

[0047] Generally, the derivation of biomass-derived alcohols tends to be costly, and it is expected that the selling price of the styrene monomers obtained through such derivation will be high. Therefore, when manufacturing styrene resins using these styrene monomers, it is considered necessary to appropriately adjust the biomass content in the styrene resin product, taking into account the price and market needs of the styrene resin product. One method for adjusting the biomass content is to mix a polymer obtained by polymerizing styrene monomers derived from biomass raw materials with a polymer obtained by polymerizing conventional styrene monomers derived from fossil fuels. However, such a method requires additional mixing steps and equipment, resulting in not only high costs but also concerns about increased environmental impact. Furthermore, the physical properties of polymers obtained from styrene monomers derived from biomass raw materials are not necessarily the same as those of polymers obtained from conventional styrene monomers derived from fossil fuels. In particular, if these properties differ significantly, there is a risk that desirable physical properties for the styrene resin cannot be obtained. On the other hand, according to the present invention's method for producing styrene-based resins, it is possible to manufacture styrene-based resins having physical properties equivalent to conventional fossil fuel-derived styrene-based resins and a sustainable ratio that can contribute to reducing the carbon footprint, while keeping costs down.

[0048] <Method for producing and molding styrene-based resin compositions> The styrene resin produced as described above can be mixed with other components, such as antioxidants, as needed, using known methods such as melt kneading, to form a styrene resin composition. The styrene resin content in 100% by mass of the styrene resin composition can be, for example, more than 90% by mass and 100% by mass or less, and can be adjusted as appropriate depending on the purpose. If the styrene resin content is 100% by mass, the above mixing is unnecessary.

[0049] If the styrene resin content is 100% by mass, the sustainability ratio of the styrene resin composition is the same as the sustainability ratio of the styrene resin. Furthermore, if components other than styrene resin contained in the styrene resin composition have a sustainability ratio, the sustainability ratio (%) of the styrene resin composition can be calculated as the sum of the sustainability ratio (%) of each component × the content (by mass) of each component / 100.

[0050] The molding method for the styrene-based resin composition is not particularly limited, and known molding methods such as press molding, extrusion molding, injection molding, injection hollow molding, blow molding, and shape extrusion molding can be employed. Furthermore, methods such as combining it with various foam molding technologies to produce a foamed molded body, or molding it into a sheet or film using a T-die sheet extruder, biaxial stretching apparatus, or inflation apparatus, are also possible. When the molded body is a sheet, it may be a single layer, or it may be used in at least one of the outer layers or only in the inner layer of a multilayer sheet. By replacing some or all of the molded bodies made from conventional styrene-based resin compositions with molded bodies made from the styrene-based resin composition of the present invention, the carbon footprint can be reduced.

[0051] <Provision of styrene-based resin products and molded articles> Styrene resins or styrene resin compositions manufactured by the above manufacturing method (hereinafter referred to as "styrene resin products") can be provided with the issuance of a Sustainability Declaration (SD) if the manufacturing site has already obtained international certification such as ISCC PLUS. Furthermore, the issuance of an SD guarantees traceability for molded articles and other products manufactured using the styrene resin products, making it possible to provide products that contribute to reducing the carbon footprint based on international certification systems. [Examples]

[0052] The present invention will be described in more detail below with reference to examples. These examples are illustrative and do not limit the scope of the present invention.

[0053] 1. Evaluation Method The physical properties of the styrene-based resins in each example and comparative example were evaluated by the following method.

[0054] <Meltmass Flow Rate (MFR)> The melt mass flow rate was measured in accordance with JIS K 7210 under conditions of 200°C and a load of 49N.

[0055] <Content of TBC and TBX in styrene-based resins> 0.2 g of styrene resin was dissolved in a small amount of THF, then 200 μL of BSTFA (M,O-bis(trimethylsilyl)trifluoroacetamide) was added to perform trimethylsilyl derivatization treatment. After settling to a final volume of 10 mL with THF, the supernatant was separated by centrifugation and measured by gas chromatography-mass spectrometry (GC / MS) under the following conditions. A pre-prepared calibration curve was used to determine the concentration. GC device: Agilent 7890A Column: Agilent DB-5ms (0.25mm id x 30m), liquid phase film thickness 0.25μm Column temperature: 50°C (1 min) → (20°C / min heating) → 320°C (6.5 min) Total 20 min Injection port: 300℃, 1.5 mL / min, (split ratio 1:5) Injection volume: 1μL MS device: Agilent 5975C Interface temperature: 320℃ MS detection conditions: SIM measurement TBC (m / z 295 for quantitative analysis, m / z 310 for confirmation)

[0056] <Weight average molecular weight (Mw)> The weight-average molecular weight (Mw) was measured using gel permeation chromatography (GPC) under the following conditions. GPC model: Shodex GPC-101 manufactured by Showa Denko Corporation Column: PLgel 10μm MIXED-B, manufactured by Polymer Laboratories, Inc. Mobile phase: tetrahydrofuran Sample concentration: 0.2% by mass Temperature: Oven 40°C, Inlet 35°C, Detector 35°C Detector: Differential refractometer The molecular weight was calculated by determining the molecular weight at each elution time from the elution curve of monodisperse polystyrene, and then calculating the molecular weight in terms of polystyrene equivalent.

[0057] <Average transmittance and YI value> The average transmittance and YI value were measured using the following procedure. Using styrene resin pellets, injection molding was performed at a cylinder temperature of 190°C and a mold temperature of 40°C to create a plate-shaped molded product measuring 115mm x 80mm x 3mm thick. For the plate-shaped molded product obtained as described above, the spectral transmittance at wavelengths of 350 nm to 800 nm was measured with incident light of size 20 × 1.6 mm and divergence angle 0°, with an optical path length of 115 mm, using a UV-Vis spectrophotometer V-670 manufactured by JASCO Corporation. The YI value at a field of view of 2° with a C light source was calculated according to JIS K7105. The average transmittance (total light transmittance) was calculated as the average of the spectral transmittance at wavelengths of 380 to 780 nm.

[0058] 2. Examples and Comparative Examples [Example 1] A polymerization process was carried out by connecting a first reactor, a fully mixed stirred tank, and a second reactor, a plug-flow type reactor with a static mixer, in series, to produce styrene-based resin. The capacity of each reactor was 30 liters for the first reactor and 12 liters for the second reactor. The raw material composition was 50% by mass of biocircular styrene (manufactured by Shell Chemicals, ISCC PLUS certified, sustainability ratio: 100%, TBC concentration 10 μg / g), 40% by mass of methyl methacrylate (TBX concentration 7 μg / g), and 10% by mass of ethylbenzene. At the inlet of the first reactor, 100 ppm of t-butyl peroxyisopropyl monocarbonate (manufactured by NOF Corporation: Perbutyl I) was added as a polymerization initiator, and 150 ppm of n-dodecyl mercaptan (manufactured by Arkema Corporation) was added as a chain transfer agent. The concentration of these additives (both based on mass relative to the raw material styrene) was adjusted accordingly. The raw material solution was then continuously supplied at 8.0 kg / h to the first reactor, which was set to 135°C. Furthermore, the resulting polymerization solution was continuously supplied to the second reactor to complete the polymerization. The monomer polymerization rate at this time was 70%. In the second reactor, a temperature gradient was created along the direction of flow, and the temperature was adjusted so that the intermediate section was 135°C and the outlet section was 145°C. Next, the polymer-containing solution continuously extracted from the second reactor was introduced into a vacuum defloration tank with a preheater, consisting of two stages in series. The preheater temperature was adjusted so that the resin temperature reached 240°C, and unreacted styrene and ethylbenzene were separated at a pressure of 0.8 kPa. The mixture was extruded in strand form through a porous die, and the strands were cooled and cut using a cold-cut method to form pellets. The resulting styrene-based resin had a styrene content of 54% by mass, a methyl methacrylate content of 46% by mass, an MFR of 2.5 g / 10 min, a weight-average molecular weight (Mw) of 186,000, a TBC content of 2.5 ppm, a TBX content of 0.6 ppm, a YI value of 1.7, an average transmittance of 88%, and a sustainability ratio of 54%.

[0059] [Example 2] A styrene-based resin was produced in the same manner as in Example 1, except that the raw material composition was changed to 20% by mass of fossil fuel-derived styrene, 30% by mass of biocircular styrene, 40% by mass of methyl methacrylate, and 10% by mass of ethylbenzene. The obtained styrene-based resin had a styrene content of 54% by mass, a methyl methacrylate content of 46% by mass, an MFR of 2.5 g / 10 min, a weight-average molecular weight (Mw) of 186,000, a TBC content of 2.5 ppm, a TBX content of 0.6 ppm, a YI value of 1.7, an average transmittance of 88%, and a sustainability ratio of 32%.

[0060] [Example 3] A styrene-based resin was produced in the same manner as in Example 1, except that the raw material composition was changed to 36% by mass of biocircular styrene, 54% by mass of methyl methacrylate, and 10% by mass of ethylbenzene, and the amount of n-dodecyl mercaptan was changed to 1000 ppm. The obtained styrene-based resin had a styrene content of 40% by mass, a methyl methacrylate content of 60% by mass, an MFR of 1.9 g / 10 min, a weight-average molecular weight (Mw) of 120,000, a TBC content of 1.4 ppm, a TBX content of 1.2 ppm, a YI value of 1.5, an average transmittance of 89%, and a sustainability ratio of 40%.

[0061] [Example 4] A styrene-based resin was produced in the same manner as in Example 1, except that the raw material composition was changed to 9% by mass of fossil fuel-derived styrene, 27% by mass of biocircular styrene, 54% by mass of methyl methacrylate, and 10% by mass of ethylbenzene, and the amount of n-dodecyl mercaptan was changed to 1000 ppm. The obtained styrene-based resin had a styrene content of 40% by mass, a methyl methacrylate content of 60% by mass, an MFR of 1.9 g / 10 min, a weight-average molecular weight (Mw) of 120,000, a TBC content of 1.4 ppm, a TBX content of 1.2 ppm, a YI value of 1.5, an average transmittance of 89%, and a sustainability ratio of 30%.

[0062] [Example 5] A styrene-based resin was produced in the same manner as in Example 1, except that the raw material composition was changed to 73% by mass of biocircular styrene, 17% by mass of methyl methacrylate, and 10% by mass of ethylbenzene, and the amount of n-dodecyl mercaptan was changed to 100 ppm. The obtained styrene-based resin had a styrene content of 80% by mass, a methyl methacrylate content of 20% by mass, an MFR of 1.7 g / 10 min, a weight-average molecular weight (Mw) of 250,000, a TBC content of 2.8 ppm, a TBX content of 0.5 ppm, a YI value of 4.5, an average transmittance of 83%, and a sustainability ratio of 80%.

[0063] [Comparative Example 1] A styrene-based resin was produced in the same manner as in Example 1, except that the raw material composition was changed to 50% by mass of fossil fuel-derived styrene, 40% by mass of methyl methacrylate, and 10% by mass of ethylbenzene. The obtained styrene-based resin had a styrene content of 54% by mass, a methyl methacrylate content of 46% by mass, an MFR of 2.5 g / 10 min, a weight-average molecular weight (Mw) of 186,000, a TBC content of 2.5 ppm, a TBX content of 0.6 ppm, a YI value of 1.7, an average transmittance of 88%, and a sustainability ratio of 0%.

[0064] The results from the examples and comparative examples show that the styrene resins of Examples 1 to 5, which use biocircular styrene, were manufactured using the same equipment and methods as the styrene resin of Comparative Example 1, which uses only styrene and methyl methacrylate derived from fossil fuels, and that they have equivalent physical properties (MFR, Mw) and a sustainable ratio that can contribute to reducing the carbon footprint. By using these styrene resins to manufacture styrene resin compositions and molded articles, it is possible to reduce the carbon footprint while suppressing costs. Furthermore, since the styrene resins of Examples 1 to 5 have the same TBC and TBX content as Comparative Example 1, they have excellent hue and transmittance and are particularly suitable as materials for optical molded articles such as light guide plates.

Claims

1. A method for producing styrene resin, comprising a polymerization step, In the polymerization step, the raw material monomer containing the styrene monomer (B) is polymerized. The styrene monomer (B) is a styrene resin manufacturing method in which a sustainable ratio of 0.1 to 100% is assigned using a mass balance method.

2. A method for producing a styrene resin according to claim 1, The aforementioned raw material monomer is a styrene-based monomer (A) derived from fossil fuels, and the method is for producing a styrene-based resin.

3. A method for producing a styrene-based resin according to claim 2, The aforementioned raw material monomer includes monomer (C), A method for producing a styrene resin, wherein the monomer (C) comprises at least one selected from the group consisting of (meth)acrylic acid ester monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides.

4. A method for producing a styrene-based resin according to claim 2 or claim 3, A method for producing a styrene resin, wherein the content of the styrene monomer (B) in the raw material monomers is 0.1 to 99.9% by mass, relative to 100% by mass of the total raw material monomers.

5. A method for producing a styrene-based resin according to any one of claims 1 to 3, A method for producing a styrene resin, wherein in the polymerization step, biocircular styrene and / or circular styrene are used as the styrene monomer (B).

6. It is a styrene-based resin, It has constituent units derived from styrene monomers, The styrene monomer comprises styrene monomer (B), A styrene-based resin in which a sustainable ratio of 0.0001% to 100% is assigned using a mass balance method.

7. The styrene-based resin according to claim 6, The styrene monomer is a styrene resin containing a styrene monomer (A) derived from fossil fuels.

8. The styrene resin according to claim 6, It has constituent units derived from monomers (C), The monomer (C) is a styrene resin comprising at least one selected from the group consisting of (meth)acrylic acid ester monomers, vinyl cyanide monomers, α,β-ethylenically unsaturated carboxylic acids, and imides.

9. The styrene-based resin according to claim 6, A styrene-based resin with a weight-average molecular weight (Mw) of 50,000 to 400,000.

10. The styrene-based resin according to claim 6, A styrene-based resin having a melt mass flow rate (MFR) of 0.1 to 30.0 g / 10 min under conditions of 200°C and a 49 N load, as measured according to JIS K 7210.

11. A molded article obtained by molding a styrene resin composition containing the styrene resin described in any one of claims 6 to 10.