Aromatic vinyl polymer resin composition and its molding

• US 20030022990A1
• Filed: 07/17/2002
• Published: 01/30/2003
• Est. Priority Date: 07/23/2001
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Petrochemical Co., Ltd. (Idemitsu Kosan Company Limited)
• Inventors: Okumura, Ryozo, Wakabayashi, Makoto, Hirota, Shogo
• Granted Patent: US 7,026,396 B2
• Time in Patent Office: Days
• US Class Current: 525/88
• CPC Class Codes: C08J 2201/03 Extrusion of the foamable blend
• CPC Class Codes: C08J 2325/06 Polystyrene
• CPC Class Codes: C08J 2453/00 Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
• CPC Class Codes: C08J 9/0061 characterized by the use of several polymeric components
• CPC Class Codes: C08J 9/122 Hydrogen, oxygen, CO2, nitrogen or noble gases
• CPC Class Codes: C08L 25/06 Polystyrene
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes

Abstract

Provided are an aromatic vinyl polymer resin composition capable of being molded into resin foam sheets having good surface smoothness and glossiness well balanced with the mechanical strength thereof even when the expansion ratio in molding is increased, and resin foam sheets and containers of the composition. The resin composition comprises (A) from 80 to 98% by mass of an aromatic vinyl polymer resin having a weight-average molecular weight measured through GPC of from 200,000 to 400,000, a ratio of weight-average molecular weight to number-average molecular weight ranging from 2.2 to 3.6, a number of branches of from 0.1 to 1.0 in one molecule having an absolute molecular weight of 1,190,000 measured through GPC-MALLS, and a melt flow rate of from 1.5 to 3.5 g/10 min, and (B) from 2 to 20% by mass of a styrene-diene block copolymer or its hydrogenate. This is molded into a resin foam sheet through extrusion foaming, and the sheet is thermoformed into containers.

Claims

1. An aromatic vinyl polymer resin composition comprising (A) from 80 to 98% by mass of an aromatic vinyl polymer resin having (1) a weight-average molecular weight (MwL) measured through GPC of from 200,000 to 400,000, (2) a ratio of weight-average molecular weight (MwL) to number-average molecular weight (MnL), (MwL)/(MnL) ranging from 2.2 to 3.6, (3) a number of branches of from 0.1 to 1.0 in one molecule having an absolute molecular weight of 1,190,000 measured through GPC-MALLS, and (4) a melt flow rate of from 1.5 to 3.5 g/10 min, and (B) from 2 to 20% by mass of a styrene-diene block copolymer or its hydrogenate.

2. The aromatic vinyl polymer resin composition as claimed in claim 1, wherein the aromatic vinyl polymer resin (A) is a polystyrene resin.

3. The aromatic vinyl polymer resin composition as claimed in claim 1 or 2, wherein the styrene-diene block copolymer or its hydrogenate (B) is a styrene-butadiene block copolymer or styrene-isoprene block copolymer or a hydrogenate thereof that contains polystyrene block structure units to an extent of from 10 to 90% by mass thereof.

4. A resin foam sheet formed by molding the aromatic vinyl polymer resin composition of any of claims 1 to 3 through extrusion foaming to an expansion ratio of from 3 to 12 times.

5. A container molded by thermoforming the resin foam sheet of claim 4.