METHOD FOR PRODUCING POLYSTYRENE-BASED RESIN EXTRUSION FOAM PLATE

• Main Authors: HIYAMA TOSHIYUKI, SUGIMOTO KENGO, NISHIYAMA NORITOSHI
• Format: Patent
• Language: English; Japanese
• Published: 26.07.2018
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

PROBLEM TO BE SOLVED: To provide a production method for stably obtaining a polystyrene-based resin extrusion foam plate which has a mechanical strength equivalent to or higher than that of a conventional polystyrene-based resin extrusion foam plate, even when hydrocarbon and an early dissipative foaming agent such as carbon dioxide and water are used together as foaming agents.SOLUTION: A method for producing an extrusion foam plate includes a step of extrusion-foaming a foamable molten resin composition obtained by kneading a polystyrene-based resin, a physical foaming agent and a bromine-based flame retardant, and shaping the resin composition into a plate shape, where the physical foaming agent contains one or more early dissipative foaming agents selected from the group consisting of carbon dioxide, water, dimethyl ether and ethanol and hydrocarbon having 3 or more and 5 or less carbon atoms, the polystyrene-based resin has a weight average absolute molecular weight of 100,000 or more and less than 300,000 as measured by GPC-MALS method and has a weight average value of a contraction factor of 0.90 or more and 1.0 or less, and a polystyrene-based resin B has a weight average absolute molecular weight of 300,000 or more and 450,000 or less as measured by GPC-MALS method and has a weight average value of a contraction factor of less than 0.90, when the total of the polystyrene-based resin A and the polystyrene-based resin B is 100 pts.wt., a blended amount of the polystyrene-based resin A contained in the polystyrene-based resin is 40 pts.wt. or more and 70 pts.wt. or less, and a blended amount of the polystyrene-based resin B is 30 pts.wt. or more and 60 pts.wt. or less.SELECTED DRAWING: None 【課題】 発泡剤として、炭化水素類と、二酸化炭素や水などの早期散逸性発泡剤とを併用した場合であっても、従来のポリスチレン系樹脂押出発泡板と比較しても機械強度に関して同等以上のポリスチレン系樹脂押出発泡板を安定して得ることができる製造方法を提供する。【解決手段】 ポリスチレン系樹脂、物理発泡剤及び臭素系難燃剤を混練してなる発泡性溶融樹脂組成物を押出発泡させ、板状に賦形する工程を含む押出発泡板の製造方法において、物理発泡剤が、二酸化炭素、水、ジメチルエーテル及びエタノールからなる群から選択される１種類以上の早期散逸性発泡剤と、炭素数３以上５以下の炭化水素とを含み、ポリスチレン系樹脂が、ＧＰＣ−ＭＡＬＳ法により測定される値で１０万以上３０万未満となる重量平均絶対分子量を有し且つ０．９０以上１．０以下となる収縮因子の重量平均値を有するポリスチレン系樹脂Ａと、ＧＰＣ−ＭＡＬＳ法により測定される値で３０万以上４５万以下となる重量平均絶対分子量を有し且つ０．９０未満となる収縮因子の重量平均値を有するポリスチレン系樹脂Ｂとを含み、ポリスチレン系樹脂Ａとポリスチレン系樹脂Ｂの合計を１００重量部とした場合に、ポリスチレン系樹脂に含まれるポリスチレン系樹脂Ａの配合量が４０重量部以上７０重量部以下であり、ポリスチレン系樹脂Ｂの配合量が３０重量部以上６０重量部以下である。【選択図】 なし