US-12617930-B2 - Resin composition, molded body using same and method for producing resin composition

Abstract

A resin composition comprising: a resin (A) having 30 mol % or more of a structural unit represented by a formula (1) below, and a boron compound (B), the boron compound (B) containing a boron element in an amount of 0.01 to 2,000 μmol per gram of the resin (A).

Inventors

• Shuichi SUNAGA
• Yuta Matsushita
• Wenjie Lu

Assignees

• KURARAY CO., LTD.

Dates

Publication Date

20260505

Application Date

20220509

Priority Date

20210512

Claims (13)

1. 1 . A resin composition comprising: a resin (A) comprising at least 30 mol % of a structural unit represented by the following formula (1), and a boron compound (B), wherein the boron compound (B) comprises from 0.01 μmol to 2,000 μmol of a boron element per gram of the resin (A)
2. 2 . A molded body comprising the resin composition of claim 1 .
3. 3 . The molded body according to claim 2 , further comprising a multilayer structure comprising a layer comprising the resin composition and at least one other layer.
4. 4 . The molded body according to claim 2 , further comprising a multilayer structure comprising a layer comprising the resin composition and a thermoplastic resin layer laminated on one surface or both surfaces of the layer.
5. 5 . The molded body according to claim 2 , wherein a layer comprising the resin composition has a thickness of from 0.01 μm to 1,000 μm.
6. 6 . A film comprising the molded body of claim 2 .
7. 7 . A packaging material comprising the film of claim 6 .
8. 8 . A method for producing a resin composition, the method comprising: bringing a resin (A) comprising at least 30 mol % of a structural unit represented by the following formula (1), a boron compound (B) and water into contact with each other
9. 9 . The method for producing a resin composition according to claim 8 , wherein the boron compound (B) is sodium borohydride or borax.
10. 10 . The method for producing a resin composition according to claim 8 , wherein the resin (A) is in a molten state.
11. 11 . The method for producing a resin composition according to claim 8 , comprising immersing the resin (A) in an aqueous solution comprising the boron compound (B).
12. 12 . The resin composition according to claim 1 , wherein the content of the structural unit represented by the formula (1) contained in the resin (A) is at least 45 mol %.
13. 13 . The method for producing a resin composition according to claim 8 , wherein the content of the structural unit represented by the formula (1) contained in the resin (A) to be brought into contact with the boron compound (B) and water is at least 45 mol %.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a National Stage entry under 35 U.S.C. § 371 of PCT/JP2022/019618, filed on May 9, 2022, and claims priority to JP Patent Application No. 2021-080742, filed on May 12, 2021, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a resin composition containing a resin having a polymethallyl alcohol unit, and a molded body using the same. Further, the present invention relates to a method for producing the resin composition. BACKGROUND ART A gas barrier material using a resin having excellent performance of blocking a gas such as oxygen (gas barrier properties) has been widely used mainly in the fields of packaging materials for a food product, a pharmaceutical, and the like, as a content. Molded bodies, like a packaging material, are generally produced by heating and melt molding, and therefore the resin is required to have thermal stability such as coloration resistance (properties in which coloration such as yellowing is not caused by heat) and long run properties (properties in which physical properties such as viscosity are not changed in long-time melt molding) in addition to the gas barrier properties. When on a layer formed from the resin, another layer is laminated, interlayer adhesive properties are also required so as to prevent easy delamination. As a resin having favorable gas barrier properties, a vinyl alcohol polymer typified by an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH), and a methallyl alcohol polymer have been reported (PTLs 1 and 2). As a resin having further favorable gas barrier properties, a polymethallyl alcohol (hereinafter sometimes abbreviated as PMAL) has been known (PTL 3). EVOH is suitably used for a gas barrier material, but the thermal stability, interlayer adhesive properties, and gas barrier properties in a high humidity environment of EVOH are not sufficient. For example, PTL 1 discloses that an EVOH composition containing predetermined amounts of carboxylic acid and alkaline earth metal has excellent appearance such as less coloration or less unevenness on a membrane surface, excellent long run properties, and excellent low odor properties during co-extrusion molding or co-injection molding with a resin having high melting point, such as a polyamide or a polyester, or during melt molding at high temperature. However, the use applications and use forms of the EVOH composition are restricted since gas barrier properties are decreased in a high humidity environment. When water vapor barrier properties are required for EVOH, which has low water vapor barrier properties, it is necessary that the EVOH is used in a multilayer structure with a material having excellent water vapor barrier properties. PTL 2 discloses that a gas barrier material formed from a resin having a methallyl alcohol unit exhibits excellent gas barrier properties at high humidity, and is excellent in transparency and melt moldability. However, there is room for improvement in thermal stability such as coloration resistance and long run properties, and interlayer adhesive properties. As a material for solving the problems, a polymethallyl alcohol resin composition having excellent gas barrier properties at high humidity and excellent thermal stability (coloration resistance and long run properties), and a molded body using the same have been reported (PTL 3). However, this report describes that it is necessary to add at least one of an acid component in which a logarithm pKa of a reciprocal of an acid dissociation constant at 25° C. is 3.5 to 7.5 and an anion of the acid component for improvement in physical properties (PTL. 3). For example, when sodium acetate is added, acetic acid may be eluted from the resin, and there is a concern about corrosion of stainless and the like used in a facility (NPL1 and PTL 4). CITATION LIST Patent Literature PTL 1: WO2001/096464PTL 2: JPH10-330508APTL 3: WO2016/104648PTL 4: JP2015-040307A Non-Patent Literature NPL1: Isao Sekine et al. “Corrosion Behavior of Type 304 Stainless Steel in Acetic Acid Solution” Boshoku Gijutsu, 33, 500-503 (1984), SUMMARY OF INVENTION Technical Problem It is an object of the present invention to provide a resin composition having excellent coloration resistance, long run properties, interlayer adhesive properties, and gas barrier properties at high humidity, a molded body using the same, and a method for producing the resin composition. Solution to Problem The inventors of the present invention have intensively studied, and as a result, found that a resin composition containing a resin having a predetermined amount or more of a structural unit represented by the following formula (1) and a predetermined amount of a boron compound is excellent in thermal stability and has excellent gas barrier properties. Based on the findings, the inventors have further studied and completed the present inve