Resin composition and film for lid material

文档序号：213947 发布日期：2021-11-05 浏览：13次中文

阅读说明：本技术 树脂组合物和盖材用膜 (Resin composition and film for lid material ) 是由逸见隆史森下功幸田真吾于 2020-03-18 设计创作，主要内容包括：本发明的目的在于,提供一种树脂组合物和盖材用膜,其对以塑料制容器、尤其是以聚对苯二甲酸乙二醇酯、聚乳酸、聚苯乙烯、聚丙烯作为材料的容器的密封性和粘接性优异,能够适合用作容器的盖材的密封层。所述树脂组合物包含：60重量份以上且95重量份以下的乙烯-乙酸乙烯酯共聚物(A)、5重量份以上且40重量份以下的增粘剂树脂(B)(在此,(A)与(B)的总和计作100重量份),所述乙烯-乙酸乙烯酯共聚物(A)中,乙酸乙烯酯含量(VA)为3重量％以上且13重量％以下,所述乙烯-乙酸乙烯酯共聚物(A)的重均分子量(Mw)与数均分子量(Mn)之比Qw为1.5以上且4.5以下。(An object of the present invention is to provide a resin composition and a film for a lid material which are excellent in sealability and adhesiveness to a container made of plastic, particularly, a container made of polyethylene terephthalate, polylactic acid, polystyrene, or polypropylene, and which can be suitably used as a sealing layer of a lid material for a container. The resin composition comprises: 60 to 95 parts by weight of an ethylene-vinyl acetate copolymer (A) having a vinyl acetate content (VA) of 3 to 13% by weight, and 5 to 40 parts by weight of a tackifier resin (B) (the sum of (A) and (B) being 100 parts by weight), wherein the ratio Qw between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the ethylene-vinyl acetate copolymer (A) is 1.5 to 4.5.)

1. A resin composition comprising: 60 to 95 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 40 parts by weight of a tackifier resin (B), wherein the total of (A) and (B) is 100 parts by weight,

the ethylene-vinyl acetate copolymer (A) has a vinyl acetate content (VA) of 3 to 13 wt%,

the ethylene-vinyl acetate copolymer (A) has a ratio Qw of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of 1.5 to 4.5.

2. The resin composition according to claim 1, further comprising 0.5 parts by weight or more and 5 parts by weight or less of a thermoplastic block copolymer (C) per 100 parts by weight of the thermoplastic block copolymer (C),

the thermoplastic block copolymer (C) contains at least either one of olefin or diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit.

3. The resin composition according to claim 1, wherein the ethylene-alpha-olefin copolymer (D) is contained in an amount of 5 parts by weight or more and 100 parts by weight or less based on 100 parts by weight of the copolymer (D),

the ethylene-alpha-olefin copolymer (D) had a density of 860kg/m as determined by JIS K6922-1 (1998)³Above and 910kg/m³The following ranges.

4. The resin composition according to claim 1, wherein the low-density polyethylene (E) is contained in an amount of 1 part by weight or more and 50 parts by weight or less based on 100 parts by weight,

the low-density polyethylene (E) has a number average molecular weight of 500 to 18000 and a melting point of 98 ℃ or higher and 120 ℃ or lower as measured by JIS K6924-2.

5. The resin composition according to claim 1, wherein the saponified ethylene-vinyl acetate copolymer (F) is contained in an amount of 1 to 100 parts by weight, based on 100 parts by weight of the saponified ethylene-vinyl acetate copolymer(s),

the ethylene-vinyl acetate copolymer saponified product (F) has a melting point, as measured in accordance with JIS K6924-2, of 90 ℃ to 120 ℃.

6. The resin composition according to claim 1, wherein the thermoplastic block copolymer (C) is contained in an amount of 0.5 to 5 parts by weight, and the ethylene- α -olefin copolymer (D) is further contained in an amount of 5 to 100 parts by weight, based on 100 parts by weight of the thermoplastic block copolymer (C),

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the ethylene-alpha-olefin copolymer (D) had a density of 860kg/m as determined by JIS K6922-1 (1998)³Above and 910kg/m³The following ranges.

7. The resin composition according to claim 1, wherein the thermoplastic block copolymer (C) is contained in an amount of 0.5 to 5 parts by weight based on 100 parts by weight, and the low-density polyethylene (E) is further contained in an amount of 1 to 50 parts by weight based on 100 parts by weight,

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the low-density polyethylene (E) has a number average molecular weight of 500 to 18000 and a melting point of 98 ℃ or higher and 120 ℃ or lower as measured by JIS K6924-2.

8. The resin composition according to claim 1, wherein the thermoplastic block copolymer (C) is contained in an amount of 0.5 to 5 parts by weight based on 100 parts by weight, and the saponified ethylene-vinyl acetate copolymer (F) is further contained in an amount of 1 to 100 parts by weight based on 100 parts by weight,

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the ethylene-vinyl acetate copolymer saponified product (F) has a melting point, as measured in accordance with JIS K6924-2, of 90 ℃ to 120 ℃.

9. The resin composition according to any one of claims 1 to 8, wherein the tackifier resin (B) is at least 1 selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized petroleum resins.

10. An adhesive for sealing, comprising the resin composition according to any one of claims 1 to 9.

11. The sealing adhesive according to claim 10, wherein the sealing adhesive is used for a container of at least 1 selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene, and polylactic acid.

12. A film for a lid material of a container, which is composed of at least 2 layers, comprising: a layer comprising the resin composition of any one of claims 1 to 9 and a support substrate layer.

Technical Field

The present invention relates to a resin composition used for a lid material of a container, and more particularly, to an adhesive resin composition which has high sealability and adhesiveness to a container and can be suitably used for sealing a lid material, and a film for a lid material having the same as a sealing layer.

Background

Conventionally, in packaging of foods, drinks, pharmaceuticals, industrial parts, and the like, plastic containers such as polyethylene, polypropylene, polystyrene, and paper containers mainly made of paper have been used, and an easily peelable film used for a lid material thereof has stable adhesiveness for protecting contents and has easy peelability capable of being opened with an appropriate strength at the time of peeling.

Although a large number of materials for easy-peeling films have been known for containers such as polypropylene and polystyrene, no easy-peeling film having practically excellent practical properties has been found for containers made of amorphous polyethylene terephthalate (hereinafter referred to as "a-PET") which has been increasingly used in recent years because of its low cost and excellent transparency and cold resistance. When the conventional easy-peeling film is used for a lid material of an A-PET container, the adhesion strength is weak, so that the lid is opened due to vibration and dropping during transportation and storage; on the other hand, when the heat sealing temperature is set high in order to obtain high adhesion strength, the container is deformed, and the sealability is lowered. Further, if the adhesive is stored in a low-temperature environment after bonding, the sealing strength is disadvantageously reduced, which is problematic in practical use.

Generally, as an adhesive for sealing a lid material, a mixture containing a tackifier and polyethylene, an ethylene-vinyl acetate copolymer, an ethylene- α -olefin copolymer, or the like is known, but among such materials, there are cases where sufficient adhesive strength and sealing strength cannot be obtained for containers of a wide range of materials from polyolefin to a-PET, and there is a problem that the lid is opened by vibration or dropping at the time of transportation or storage due to poor adhesive strength; on the other hand, when the heat sealing temperature is set high in order to obtain high adhesion strength, there is a problem that the container is deformed to lower the sealability. Further, resin compositions comprising an ethylene- α -olefin copolymer and an olefin elastomer and/or a styrene elastomer and a tackifier (see, for example, patent document 1), and sealing materials comprising an ethylene- α -olefin copolymer, an ethylene-polar monomer copolymer, an a-B-a type block copolymer, and a tackifier (see, for example, patent document 2) have been used, but they cannot satisfy all the requirements of molding processability, sealing strength, and adhesive strength.

Further, in recent years, demands for biodegradable plastics have been increasing due to increased awareness of environmental protection. In the field of food packaging materials, the amount of biodegradable plastics such as polylactic acid (PLA) used as the material of containers has been increasing, but conventional adhesive resins for sealing used for such lids have not been said to have sufficient adhesiveness to PLA and the like, and there is still a demand for adhesive resins that can be suitably used for these applications.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 1999-269319

Patent document 2: japanese patent No. 4438108

Disclosure of Invention

Technical problem to be solved by the invention

The present invention aims to provide a resin composition and a film for a lid material which are excellent in sealing properties and adhesion properties to a container made of plastic, particularly a container made of polyethylene terephthalate, polylactic acid, polystyrene, or polypropylene, and which can be suitably used as a sealing layer of a lid material for a container.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that a resin composition comprising an ethylene-vinyl acetate copolymer having specific properties and a tackifier is excellent in sealing properties and adhesion properties to various plastic containers including a-PET and polylactic acid, thereby completing the present invention.

Namely, the present invention resides in the following [1] to [12 ].

[1] A resin composition comprising: 60 to 95 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 40 parts by weight of a tackifier resin (B) (the total of (A) and (B) being 100 parts by weight),

the ethylene-vinyl acetate copolymer (A) has a vinyl acetate content (VA) of 3 to 13 wt%,

the ethylene-vinyl acetate copolymer (A) has a ratio Qw of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of 1.5 to 4.5.

[2] A resin composition further comprising 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) per 100 parts by weight of the resin composition according to [1],

the thermoplastic block copolymer (C) contains at least either one of olefin or diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit.

[3] A resin composition comprising 5 to 100 parts by weight of an ethylene-alpha-olefin copolymer (D) per 100 parts by weight of the resin composition according to [1],

the ethylene-alpha-olefin copolymer (D) had a density of 860kg/m as determined by JIS K6922-1 (1998)³Above and 910kg/m³The following ranges.

[4] A resin composition comprising 1 to 50 parts by weight of a low-density polyethylene (E) per 100 parts by weight of the resin composition according to [1],

the low-density polyethylene (E) has a number average molecular weight of 500 to 18000, and a melting point of 98 ℃ or higher and 120 ℃ or lower as measured by JIS K6924-2.

[5] A resin composition comprising 1 to 100 parts by weight of a saponified ethylene-vinyl acetate copolymer (F), based on 100 parts by weight of the resin composition according to [1],

the ethylene-vinyl acetate copolymer saponified product (F) has a melting point, as measured in accordance with JIS K6924-2, of 90 ℃ to 120 ℃.

[6] A resin composition comprising 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) and 5 to 100 parts by weight of an ethylene-alpha-olefin copolymer (D) per 100 parts by weight of the resin composition according to [1],

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the ethylene-alpha-olefin copolymer (D) had a density of 860kg/m as determined by JIS K6922-1 (1998)³Above and 910kg/m³The following ranges.

[7] A resin composition comprising 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) and 1 to 50 parts by weight of a low-density polyethylene (E) per 100 parts by weight of the resin composition according to [1],

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the low-density polyethylene (E) has a number average molecular weight of 500 to 18000, and a melting point of 98 ℃ or higher and 120 ℃ or lower as measured by JIS K6924-2.

[8] A resin composition comprising 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) per 100 parts by weight of the resin composition according to [1] above, and further comprising 1 to 100 parts by weight of a saponified ethylene-vinyl acetate copolymer (F),

the thermoplastic block copolymer (C) contains at least either one of an olefin or a diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit;

the ethylene-vinyl acetate copolymer saponified product (F) has a melting point, as measured in accordance with JIS K6924-2, of 90 ℃ to 120 ℃.

[9] The resin composition according to any one of the above [1] to [8], wherein the tackifier resin (B) is at least 1 selected from the group consisting of an aliphatic petroleum resin, an aromatic petroleum resin, an alicyclic hydrogenated petroleum resin, and a copolymerized petroleum resin.

[10] An adhesive for sealing, comprising the resin composition according to any one of the above [1] to [9 ].

[11] The sealing adhesive according to the above [10], which is used for a container comprising at least 1 selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene and polylactic acid.

[12] A film for a lid material of a container, which is composed of at least 2 layers, comprising: a layer comprising the resin composition described in any one of the above [1] to [9] and a support base layer.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a resin composition which is excellent in sealability and adhesiveness to various types of plastic containers, particularly containers made of polyethylene terephthalate, polylactic acid, polystyrene, or polypropylene, and which can be used as a sealing adhesive layer for producing a lid material for containers.

Detailed Description

Hereinafter, a resin composition as one aspect of the present invention will be described in detail.

The ethylene-vinyl acetate copolymer (a) constituting the present invention has a vinyl acetate content of 3 wt% or more and 15 wt% or less, preferably 3 wt% or more and 13 wt% or less, and more preferably 5 wt% or more and 10 wt% or less. When the vinyl acetate content is less than 3% by weight, the resultant composition is poor in low-temperature heat sealability, and is not preferred. On the other hand, when the vinyl acetate content is more than 15% by weight, the resultant composition is not preferable because the moldability and the adhesive strength are poor.

Here, the vinyl acetate content in the ethylene-vinyl acetate copolymer can be measured by a method in accordance with JIS K6924-1.

The ethylene-vinyl acetate copolymer (a) constituting the present invention has a ratio Mw/Mn (hereinafter referred to as "Qw") of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 1.5 or more and 4.5 or less, preferably 2.0 or more and 4.5 or less, and more preferably 2.5 or more and 4.2 or less. When Qw is less than 1.5, the extrusion load during molding becomes high, and energy consumption becomes large, which is not preferable. When Qw is more than 4.5, the adhesive strength and the sealing strength of the composition of the present invention are undesirably low.

Here, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the ethylene-vinyl acetate copolymer (a) can be calculated as the molecular weight of the linear polyethylene by measuring a universal calibration curve using, for example, gel permeation chromatography.

Further, it is preferable that the ethylene-vinyl acetate copolymer (A) of the present invention has a vinyl acetate content VA (unit: weight%) and Qw satisfying the following relational expression (1) because the adhesive strength and the sealing strength of the composition of the present invention are high.

Qw<-1.9×lnVA+9.0 (1)

In this case, lnVA represents the natural logarithm of the vinyl acetate content VA (% by weight).

The ethylene-vinyl acetate copolymer (a) constituting the present invention can be obtained by a known production method, and the production method is not particularly limited, and an ethylene-vinyl acetate copolymer having a vinyl acetate content and a Qw satisfying the requirements of the present application can be easily obtained by a method of performing radical polymerization under high pressure using a Tubular (Tubular) reactor, and is therefore preferable.

The ethylene-vinyl acetate copolymer (a) in the present invention may be a single component, or may be any of compositions containing 2 or more kinds of copolymers. When the copolymer (A) is a composition, the vinyl acetate content of the composition is a value measured by the method described in JIS K6924-1. Similarly, the term "Qw" as a composition means a value measured by the aforementioned method using gel permeation chromatography. The vinyl acetate content and the ratio Qw of the weight-average molecular weight to the number-average molecular weight measured for these compositions are sufficient as long as the requirements of the ethylene-vinyl acetate copolymer (A) are satisfied.

The tackifier resin (B) constituting the present invention may be any one as long as it falls within the category of the tackifier resin. Examples of the tackifier resin (B) include: petroleum resins, coumarone resins, styrenes, and the like as synthetic petroleum resin tackifiers; rosin resins, methyl ester resins, glycerol ester resins, pentaerythritol ester resins, terpene resins, and modified products thereof, which are natural resin tackifiers. Among these tackifier resins, synthetic petroleum resin tackifiers include aliphatic petroleum resins, aliphatic hydrogenated petroleum resins, aromatic hydrogenated petroleum resins, alicyclic hydrogenated petroleum resins, copolymerized hydrogenated petroleum resins, and the like. Among these, it is preferable to use either an aromatic hydrogenated petroleum resin or an alicyclic hydrogenated petroleum resin. In particular, a tackifier resin containing at least 1 selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized petroleum resins is preferable because it is excellent in sealability and adhesiveness.

The softening point of the tackifier resin (B) constituting the present invention measured by the ring and ball method is preferably in the range of 90 ℃ to 140 ℃, more preferably 100 ℃ to 135 ℃, and even more preferably 105 ℃ to 130 ℃. When the softening point is within the above range, blocking of the film after molding is reduced, and the adhesive strength retention property in a low-temperature environment is suitable.

Commercially available tackifier resins (B) constituting the present invention can be used. Specifically, examples of the petroleum resins include (trade name) ARKON P100, ARKON P125, ARKON P140, ARKON M90, ARKON M115, ARKON M135 (manufactured by Okawa chemical industries, Ltd.), I-MARV S110, I-MARV P125 (manufactured by Kakko corporation), T-REZ RC115, and T-REZ HA125 (manufactured by JXTG ENERGY Co., Ltd.). Examples of the rosin-based resin include PINECRYSTAL KE-311 (available from Ishikawa chemical Co., Ltd.). Examples of the terpene RESIN include YS RESIN PX1150 and YS RESIN PX1150N (manufactured by YASUHARA CHEMICAL Co., Ltd.).

The blending ratio of the ethylene-vinyl acetate copolymer (a) and the tackifier resin (B) constituting the present invention is as follows. Here, the sum of (A) and (B) is 100 parts by weight.

The blending ratio of the ethylene-vinyl acetate copolymer (a) constituting the present invention is 60 parts by weight or more and 95 parts by weight or less, preferably 70 parts by weight or more and 90 parts by weight or less, and more preferably 75 parts by weight or more and 90 parts by weight or less. When the blending proportion of (A) is less than 60 parts by weight, the resulting resin composition is not preferable because the molding stability is poor. On the other hand, if the amount is more than 95 parts by weight, the sealing property and adhesion of the resulting resin composition will be insufficient, which is not preferable. (A) The blending ratio of (b) is preferably 81 parts by weight or more and 90 parts by weight or less. Thus, the resin composition of the present application can maintain sufficient adhesive strength and sealing strength even if the amount of the tackifier (B) to be blended is reduced.

The blending ratio of the tackifier resin (B) constituting the present invention is 5 parts by weight or more and 40 parts by weight or less, preferably 10 parts by weight or more and 30 parts by weight or less, and more preferably 10 parts by weight or more and 25 parts by weight or less. When the blending ratio of (B) is less than 5 parts by weight, the sealing property and adhesion of the resulting resin composition become insufficient, which is not preferable. On the other hand, in the case of more than 40 parts by weight, blocking between the film becomes severe when the film is formed into a film shape, which may adversely affect secondary processing and also reduce sealability, and therefore, such is not preferable. (B) The blending ratio of (b) is preferably 10 parts by weight or more and 19 parts by weight or less. Thus, the resin composition of the present application can maintain sufficient adhesive strength and sealing strength even if the amount of the tackifier (B) to be blended is reduced.

That is, in the resin composition of the present application, the blending ratio of (a) is preferably 81 parts by weight or more and 90 parts by weight or less, and the blending ratio of (B) is preferably 10 parts by weight or more and 19 parts by weight or less (here, the total of (a) and (B) is 100 parts by weight).

The resin composition of the present invention may contain a thermoplastic block copolymer (C) containing at least either one of an olefin and a diene as a structural unit and containing a vinyl aromatic hydrocarbon as a structural unit. The thermoplastic block copolymer (C) is represented by the following formula.

(A-B)n

(A-B)n-A'

(A-B)m-X

(wherein A and A' each independently represent a vinyl aromatic hydrocarbon polymer block, B represents any polymer block of olefin or diene, n represents an integer of 1 to 5, m represents an integer of 2 to 7, and X represents a polyfunctional compound having a valence of m).

The thermoplastic block copolymer (C) is a polymer having at least one structure selected from a linear structure, a radial structure and a branched structure, and having a block structure as a vinyl aromatic hydrocarbon polymer block at least at one end. The thermoplastic block copolymer (c) may also be a hydrogenated product thereof.

Examples of the vinyl aromatic hydrocarbon used herein include styrene, α -methylstyrene, vinyltoluene, p-tert-butylstyrene, vinylxylene, ethylvinylxylene, vinylnaphthalene, and a mixture thereof. Among these, styrene is particularly preferable.

Examples of the olefin to be used include α -olefins such as ethylene, propylene, and 1-butene, and examples of the diene include conjugated dienes such as butadiene and isoprene.

As the thermoplastic block copolymer (C), as long as the olefin unit is dominant in the block B, a copolymer of either an olefin or a conjugated diene and a vinyl aromatic hydrocarbon is preferably used, and a copolymer obtained by hydrogenating a polymer block obtained by polymerizing a conjugated diene is more preferably used. In the present invention, a thermoplastic block copolymer of a vinyl aromatic hydrocarbon and an olefin or a diene, which has a vinyl aromatic hydrocarbon polymer block at both ends, is preferable, and particularly, a hydrogenated product of a polystyrene-polybutadiene-polystyrene block copolymer (styrene-ethylene/butylene-styrene triblock copolymer, hereinafter referred to as "hydrogenated SEBS") can be particularly preferably used from the viewpoint of improving thermal stability.

The thermoplastic block copolymer (C) constituting the resin composition of the present invention may be a copolymer containing a single component, or may be a composition containing at least 2 or more kinds of copolymers. Particularly, from the viewpoint of forming a sealing adhesive excellent in moldability and adhesive strength, a composition mixture of a hydrogenated styrene-butadiene-diblock copolymer and a hydrogenated styrene-butadiene-styrene-triblock copolymer is preferred, and the mixing ratio thereof is preferably 5/5 to 9/1 in terms of diblock/triblock conversion. The styrene content in the mixture is preferably 10% by weight or more and 50% by weight or less with respect to the total amount of the thermoplastic block copolymer (C).

As a method for measuring the styrene content, the following method can be exemplified: determination of the Infrared absorption Spectrum for Standard samples with known styrene content, using 700cm^-1The absorption intensity derived from the benzene ring in the vicinity was plotted as a calibration curve, and the styrene content was determined from the absorption intensity derived from the benzene ring of a sample with an unknown content.

The blending ratio of the vinyl aromatic hydrocarbon and the thermoplastic block copolymer of olefin or diene (C) constituting the present invention is preferably 0.5 parts by weight or more and 5 parts by weight or less, more preferably 1 part by weight or more and 5 parts by weight or less, and further preferably 2 parts by weight or more and 4 parts by weight or less, based on 100 parts by weight of the total of the mixture of the ethylene-vinyl acetate copolymer (a) and the tackifier resin (B).

The thermoplastic block copolymer (C) of a vinyl aromatic hydrocarbon and an olefin or a diene of the present invention may be a commercially available one. Specifically, for example, (trade name) KRATON G1726VS, KRATON G1657VS, KRATON G1730VS (manufactured by KRATON POLYMER CORPORATION, supra) and the like can be exemplified.

The resin composition of the present invention may contain an ethylene- α -olefin copolymer (D). Any ethylene- α -olefin copolymer (D) may be used as long as it falls within the category generally referred to as ethylene- α -olefin copolymers. The α -olefin is not particularly limited, and examples thereof include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecane having 3 to 12 carbon atoms. These ethylene- α -olefin copolymers (D) can be suitably produced by copolymerizing ethylene and α -olefin using a ziegler-based catalyst, a chromium-based catalyst, or a metallocene catalyst. Examples of the polymerization method include a solution polymerization method, a high pressure polymerization method, and a gas phase polymerization method.

The ethylene-alpha-olefin copolymer (D) constituting the present invention preferably has a density of 860kg/m measured in JIS K6922-1 (1998) from the viewpoint of excellent low-temperature sealability and seal strength³Above and 910kg/m³The following ranges.

The blending ratio of the ethylene- α -olefin copolymer (D) constituting the present invention is preferably 5 parts by weight or more and 100 parts by weight or less, more preferably 10 parts by weight or more and 50 parts by weight or less, and further preferably 18 parts by weight or more and 40 parts by weight or less, based on 100 parts by weight of the total of the mixture of the ethylene-vinyl acetate copolymer (a) and the tackifier resin (B).

The resin composition of the present invention may contain low-density polyethylene (E).

The low-density polyethylene (E) constituting the resin composition of the present invention is preferably a low-density polyethylene obtained by polymerizing only ethylene by a known high-pressure polymerization method, and the density measured in accordance with JIS K6922-1 is in the range of 910kg/m³Above 940kg/m³The following. The number average molecular weight (Mn) of the low-density polyethylene (E) is preferably in the range of 500 to 18000, more preferably 1000 to 15000, and further preferably 1000 to 13000. The melting point of the low-density polyethylene (E) is preferably in the range of 98 ℃ to 120 ℃, more preferably 100 ℃ to 110 ℃.

The blending proportion of the low-density polyethylene (E) constituting the present invention is preferably 1 part by weight or more and 50 parts by weight or less, more preferably 5 parts by weight or more and 30 parts by weight or less, and further preferably 8 parts by weight or more and 25 parts by weight or less, relative to 100 parts by weight of the total of the mixture of the ethylene-vinyl acetate copolymer (a) and the tackifier resin (B).

Commercially available low-density polyethylene (E) constituting the present invention can be used. Specifically, for example, SANWAX (product name) (manufactured by Sanyo chemical Co., Ltd.) and Hi-WAX (manufactured by Mitsui chemical Co., Ltd.) can be exemplified.

The resin composition of the present invention may contain a saponified ethylene-vinyl acetate copolymer (F).

The saponified ethylene-vinyl acetate copolymer (F) constituting the present invention can be produced by a known production method, for example, by a hydrolysis reaction of an ethylene-vinyl acetate copolymer using an alkali or an acid as a catalyst, and more specific production methods include, for example, the following methods: a homogeneous saponification method in which an ethylene-vinyl acetate copolymer as a raw material is dissolved in a good solvent and reacted in a homogeneous system, or a heterogeneous saponification method in which a reaction is directly performed in a poor solvent such as methanol or ethanol in the form of pellets or powder in a heterogeneous system. The ethylene-vinyl acetate copolymer in this case may be produced by a known method, for example, a known production method such as a high pressure method or an emulsion method, or may be a commercially available product.

The melting point of the ethylene-vinyl alcohol copolymer (F) constituting the present invention as measured by JIS K6924-2 is preferably 90 ℃ or higher and 120 ℃ or lower, more preferably 100 ℃ or higher and 115 ℃ or lower.

The saponified ethylene-vinyl acetate copolymer (F) constituting the present invention may contain vinyl acetate in the molecular structure. The vinyl acetate content is preferably 40% by weight or less, more preferably 25% by weight or less. In the saponified product, vinyl acetate is not contained when the saponification rate is 100%, and therefore the vinyl acetate content reaches 0%. Namely, the vinyl acetate content is 0% or more.

The vinyl alcohol content in the saponified ethylene-vinyl acetate copolymer (F) constituting the present invention is preferably 1.2% by weight or more and 50% by weight or less, and more preferably 3% by weight or more and 20% by weight or less. The vinyl alcohol content is preferably higher than the vinyl acetate content.

The blending ratio of the ethylene-vinyl acetate copolymer saponified product (F) constituting the present invention is preferably 1 part by weight or more and 100 parts by weight or less, more preferably 5 parts by weight or more and 30 parts by weight or less, and still more preferably 8 parts by weight or more and 20 parts by weight or less, with respect to 100 parts by weight of the mixture of the ethylene-vinyl acetate copolymer (a) and the tackifier resin (B), from the viewpoint of excellent low-temperature sealability and heat seal strength.

Commercially available materials can be used as the saponified ethylene-vinyl acetate copolymer (F) constituting the present invention. Specifically, for example, (trade name) メルセン H (manufactured by Tosoh corporation) and the like can be exemplified.

The resin composition of the present invention comprises an ethylene-vinyl acetate copolymer (a) and a tackifier resin (B), and may further comprise 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) and 5 to 100 parts by weight of an ethylene- α -olefin copolymer (D), based on 100 parts by weight of the sum of (a) and (B); the thermoplastic block copolymer (C) contains at least either olefin or diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit; the ethylene-alpha-olefin copolymer (D) had a density of 860kg/m as determined by JIS K6922-1 (1998)³Above and 910kg/m³The following ranges.

The resin composition of the present invention comprises an ethylene-vinyl acetate copolymer (a) and a tackifier resin (B), and may further comprise 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) and 1 to 50 parts by weight of a low-density polyethylene (E), based on 100 parts by weight of the sum of (a) and (B); the thermoplastic block copolymer (C) contains at least either olefin or diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit; the low-density polyethylene (E) has a number average molecular weight of 500 to 18000 and a melting point of 98 ℃ to 120 ℃.

The resin composition of the present invention comprises an ethylene-vinyl acetate copolymer (a) and a tackifier resin (B), and may further comprise 0.5 to 5 parts by weight of a thermoplastic block copolymer (C) per 100 parts by weight of the total of (a) and (B), and 1 to 100 parts by weight of a saponified ethylene-vinyl acetate copolymer (F); the thermoplastic block copolymer (C) contains at least either olefin or diene as a structural unit, and contains a vinyl aromatic hydrocarbon as a structural unit; the ethylene-vinyl acetate copolymer saponified product (F) has a melting point of 90-120 ℃ as measured in accordance with JIS K6924-2.

The resin composition of the present invention may contain other thermoplastic resins, rubbers, and light stabilizers, ultraviolet absorbers, nucleating agents, lubricants, antioxidants, antiblocking agents, flowability improvers, mold release agents, flame retardants, colorants, inorganic neutralizers, hydrochloric acid absorbers, filler conductive agents, and the like, as long as the effects of the present invention are not impaired.

The method for producing the resin composition of the present invention is not particularly limited, and examples thereof include the following methods: the ethylene-vinyl acetate copolymer (a), the tackifier resin (B) and the materials blended therewith are preblended by a mixer such as a henschel mixer or a tumbler mixer at the same time, and then melt-kneaded by a single-screw or two-screw extruder.

The sealing adhesive according to one aspect of the present invention will be described in detail below.

The resin composition of the present invention can be used as an adhesive. In particular, the resin composition can be suitably used as an adhesive for sealing plastic containers, particularly as an adhesive for sealing lidstock, which comprises a resin as a main component such as polyethylene terephthalate, polystyrene, or polypropylene, or a variety of other resins as a main component. Here, the term "seal" refers to use in the application of a sealed container. By using the lid sealing adhesive of the present invention, the lid and the container can be sealed.

Specific examples of the material of the plastic container include polyolefin resin, acrylic resin, polyamide resin, polyester resin, polycarbonate resin, polystyrene resin, styrene-acrylonitrile copolymer, and polyvinyl chloride resin.

Examples of the polyolefin resin include low-density polyethylene, high-density polyethylene, ethylene- α -olefin copolymer, ethylene-vinyl acetate copolymer, and polypropylene.

Examples of the acrylic resin include polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, octyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, and octyl methacrylate.

Examples of the polyamide resin include nylon 6, nylon 11, and nylon 12.

Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, and a stereocomplex of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly (succinic acid/butylene adipate), polyethylene succinate, poly (succinic acid/butylene terephthalate), poly (adipic acid/butylene terephthalate), poly (hydroxybutyrate/hydroxyhexanoate), polyglycolic acid, poly (3-hydroxybutyrate), and polycaprolactone.

When the resin composition of the present invention is used as an adhesive for bonding a plastic container containing these materials, the main component of the plastic container may be a single component or a composition of a plurality of resins. The container may be a multilayer structure in which a plurality of materials are stacked.

The resin composition of the present invention can be suitably used for containers made of polyethylene terephthalate, polylactic acid, polystyrene, or polypropylene.

Hereinafter, a film for a lid material, which is one aspect of the present invention, will be described in detail.

When the resin composition of the present invention is used as an adhesive, the resin composition is preferably used as an adhesive layer containing the composition (hereinafter referred to as "sealing adhesive layer"), and further, the resin composition can be suitably used as a film for a lid material which comprises at least 2 layers of a support base layer and a sealing adhesive layer and has a structure in which the sealing adhesive layer is the outermost layer.

The support base material constituting the support base material layer is not particularly limited as long as it has self-supporting properties, and examples thereof include: a plastic film composed of the following thermoplastic resins: olefin resins such as polyethylene, polypropylene, ethylene- α -olefin copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate copolymer saponified product, polyethylene terephthalate, polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, copolymers of L-lactic acid and D-lactic acid, stereocomplex of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly (succinic acid/butylene adipate), polyethylene succinate, poly (succinic acid/butylene terephthalate), poly (adipic acid/butylene terephthalate), poly (hydroxybutyrate/hydroxyhexanoate), polyglycolic acid, poly (3-hydroxybutyrate, poly (hydroxyhexanoate), poly (ethylene-co-olefin copolymer), ethylene-vinyl acetate copolymer, and ethylene-vinyl acetate copolymer saponified product, Polyester resins such as polycaprolactone, polyamide resins such as nylon 6, nylon 11, and nylon 12, and the like; paper such as japanese paper and composite paper; a metal foil made of metal such as aluminum; a vapor-deposited film obtained by vapor-depositing aluminum, silicon dioxide, or the like on a surface of a polyester resin film or the like; and a single or a laminate of the above materials. The thickness of the support base layer can be selected according to the application within a range that does not impair mechanical strength, workability, and the like, and is generally about 5 to 100 μm, preferably 10 to 50 μm.

When the film is used as a film for a cover material, the thickness of the sealing adhesive layer may be selected according to the application within a range not impairing the adhesiveness, workability, and the like, and is generally about 5 to 50 μm, preferably 10 to 40 μm, and more preferably 15 to 30 μm.

In the present invention, an intermediate layer may be provided between the support base layer and the sealing adhesive layer in order to improve adhesion between the two layers. The intermediate layer may be composed of a thermoplastic resin such as polyolefin, a thermoplastic elastomer, or the like, and these components may be used alone or in combination of 2 or more. Examples of the polyolefin include polyethylene, ethylene copolymers (ethylene- α -olefin copolymers, propylene-ethylene copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl acrylate copolymers, and the like), and modified products thereof. Various additives, for example, antioxidants, lubricants, antistatic agents, conductive agents, antiblocking agents, and tackifiers may be added to the intermediate layer within a range not to impair the effects of the present invention.

The thickness of the intermediate layer can be selected according to the application within the range not impairing the workability, and is generally about 5 to 30 μm.

In the present invention, an anchor coat layer such as polyurethane may be provided between the support base material layer and the sealing adhesive layer or between the support base material layer and the intermediate layer in order to improve adhesion between the two layers.

The film for a lid material having the sealing adhesive layer of the present invention as the outermost layer is suitable as a lid material for various types of plastic containers in addition to a-PET, and has high sealing strength and easy peelability.

The method for producing the film for a cover material is not particularly limited, and examples thereof include a method of laminating a sealing adhesive and a supporting base material layer, a method of co-extruding a sealing adhesive and a supporting base material layer, and the like.

Examples of the method of lamination include: (1) an extrusion lamination method in which a primer coating agent (coating agent) is applied to a support base layer and the adhesive layer is melt-extruded; (2) an extrusion lamination method in which a primer is applied to the support base layer, the intermediate layer is melt-extruded, and then the sealing adhesive layer is melt-extruded thereon; (3) an extrusion lamination method in which an intermediate layer having excellent adhesion to a support base material such as an ethylene-methacrylic acid copolymer or an ethylene-methyl methacrylate copolymer is melt-extruded on a support base material layer, and then a sealing adhesive layer is melt-extruded thereon; (4) a coextrusion lamination method in which a primer is applied to the support base layer and the intermediate layer and the adhesive layer are simultaneously melt-extruded; (5) a coextrusion lamination method in which an intermediate layer excellent in adhesion to a support base material such as an ethylene-methacrylic acid copolymer or an ethylene-methyl methacrylate copolymer and a sealing adhesive layer are simultaneously melt-extruded on a support base material layer; (6) a dry lamination method in which a film containing at least 1 layer of sealing adhesive is formed in advance by inflation molding or tape casting molding and is bonded to a support base material layer coated with a primer; (7) a sandwich extrusion lamination method in which extrusion lamination is performed between a support base layer coated with a primer and a film containing at least 1 layer of a sealing adhesive, and the intermediate layer is melt-extruded and laminated, and the like. On the other hand, as a method of co-extruding the sealing adhesive and the support base layer, a co-extrusion inflation method, a co-extrusion T-die method, and the like can be exemplified.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(measurement of molecular weight of ethylene-vinyl acetate copolymer (A))

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the ethylene-vinyl acetate copolymer (a) were calculated as the molecular weight of linear polyethylene by measuring a universal calibration curve with monodisperse polystyrene under the conditions shown below using a gel permeation chromatography.

The machine is as follows: 150C ALC/GPC, WATERS Inc

Solvent: 1,2, 4-trichlorobenzene

Flow rate: 1ml/min

Temperature: 140 deg.C

And (3) measuring the concentration: 30mg/30ml

Injection amount: 100 μ l

Column: TSKgel GMH HR-H3 root made by Tosoh

The ratio of Mw to Mn is shown in Table 5.

The film for a lid material obtained in the example was measured for sealing strength and adhesive strength by the following methods.

(measurement of seal Strength)

The adhesive surface of the film for a lid material was bonded to a cup made of amorphous polyethylene terephthalate (A-PET) (65 mm in diameter, 2mm in flange width, 215ml in capacity) by applying pressure and heat at 160 ℃ for 1 second at 40 Kgf/cup using a cup sealer (model UF-500 manufactured by サニーカップ Co.). After leaving to cool, the rupture strength was measured using a seal tester (manufactured by SUN scientific Co., Ltd., type FKT-100J) under the condition that the air injection amount was 0.8L/min. The strength obtained here was taken as the seal strength.

(measurement of adhesive Strength)

The adhesive strength was measured according to the method described in JIS Z0238. The adhesive surface of the film for the lid material was superposed on an A-PET sheet (available from MINERON CHEMICAL CO., LTD.) having a thickness of 0.35mm, and pressure-heated and bonded with a sealing bar having a width of 20mm at 170 ℃ and 0.2MPa for 1 second by using a heat seal TESTER (model TP-701 available from TESTER SANGYO CO., LTD.). After the sheet was left to cool, the sheet was cut into short strips of 15mm width at right angles to the width direction of the adhesive surface, and the strips were used as test pieces. The test piece was subjected to tensile strength measurement using a tensile tester (RTE-1210, manufactured by A & D) under conditions of a peel angle of 180 degrees, a peel speed of 300 mm/min, and an inter-jig distance of 40 mm. The measured value of the portion where the tensile strength was stable was taken as the adhesion strength.

Example 1

85 parts by weight of a resin (A-1) having a vinyl acetate content of 5.0%, a melt mass flow rate of 1.0g/10 min and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 3.8 as an ethylene-vinyl acetate copolymer (A) and 15 parts by weight of a fully hydrogenated petroleum resin (B-1) (ARKON P125, trade name: ARKON 125, softening temperature: 125 ℃ C., manufactured by Mitsukawa chemical Co., Ltd.) as a tackifier resin (B) were preblended with a tumbler mixer and then melt-kneaded at 180 ℃ using a twin-screw extruder to obtain pellets of the resin composition. In consideration of thermal stability, 0.05 part by weight of a phenol antioxidant (product name of Irganox1010, manufactured by BASF corporation) and 0.2 part by weight of a lubricant (product name of アーモワックス E, manufactured by LION AKZO corporation) were added to 100 parts by weight of the sealing adhesive in the resin composition.

Then, low-density polyethylene (25 μm thick, manufactured by Tosoh corporation, trade name ペトロセン 203) as an intermediate layer was extrusion-laminated on a biaxially stretched polyester film (12 μm thick) as a support base layer in advance, and pellets of the resin composition were extrusion-laminated on the surface of the low-density polyethylene of the obtained 2-layer film at a processing temperature of 230 ℃ using an extrusion laminator (manufactured by PLACO corporation, screw diameter 25 mm. phi.) to obtain a film for a lid material having a thickness of 15 μm of the resin composition layer.

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Example 2

A resin composition and a film for a covering material were obtained in the same manner as in example 1 except that 3 parts by weight of a thermoplastic block copolymer (C-1) of vinyl aromatic hydrocarbon and diene having a styrene content of 30% by weight (KRATON G1726VS) and a hydrogenated styrene-butadiene-styrene triblock copolymer (C) having a mixing ratio of 7/3 to the hydrogenated styrene-butadiene-diblock copolymer and the hydrogenated styrene-butadiene-styrene triblock copolymer as the thermoplastic block copolymer (C) were further mixed with the resin composition containing the ethylene-vinyl acetate copolymer (a-1) and the tackifier resin (B-1) of example 1.

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Example 3

A resin composition and a film for a covering material were obtained in the same manner as in example 1 except that 85 parts by weight of the resin (a-2) having a vinyl acetate content of 7.5%, a melt mass flow rate of 2.0g/10 min, and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 4.2 was blended instead of 85 parts by weight of the ethylene-vinyl acetate copolymer (a-1).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Example 4

A resin composition and a film for a covering material were obtained in the same manner as in example 2 except that 85 parts by weight of the resin (a-2) having a vinyl acetate content of 7.5%, a melt mass flow rate of 2.0g/10 min, and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 4.2 was blended instead of 85 parts by weight of the ethylene-vinyl acetate copolymer (a-1).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Example 5

The resin composition of example 2 was compounded with an ethylene- α -olefin copolymer (D) having a density of 860kg/m³B ofA resin composition and a film for a covering material were obtained in the same manner as in example 1 except that 20 parts by weight of an ene-olefin copolymer (D-1) (product name: TAFMER P-0375, manufactured by Mitsui chemical Co., Ltd.).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Example 6

A resin composition and a film for a cap material were obtained in the same manner as in example 1 except that 10 parts by weight of low-density polyethylene (E-1) (manufactured by sanyo chemical industries, ltd.) having a number average molecular weight (Mn) of 2000 and a melting point of 107 ℃ was blended as the low-density polyethylene (E) to the resin composition of example 2.

The evaluation results of the obtained sealing adhesive and lid film are shown in table 1.

Example 7

A resin composition and a film for a cap material were obtained in the same manner as in example 1 except that 10 parts by weight of an ethylene-vinyl acetate copolymer saponified product (F-1) (product name: メルセン H6051, manufactured by Tosoh corporation) having a melting point of 107 ℃ and a melt mass flow rate of 5.5g/10 min was added to the resin composition of example 2 as the ethylene-vinyl acetate copolymer saponified product (F).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 1.

Comparative example 1

A resin composition and a film for a cap material were obtained in the same manner as in example 1 except that 85 parts by weight of a resin (A-3) (product name: ウルトラセン 520F, manufactured by Tosoh corporation, trade name: ウルトラセン F) having a vinyl acetate content of 7.5%, a melt mass flow rate of 2.0g/10 min, and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 6.4 was blended in place of 85 parts by weight of the ethylene-vinyl acetate copolymer (A-1).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 2. The obtained film for a lid material had poor adhesive strength and sealing strength.

Comparative example 2

A resin composition and a film for a cap material were obtained in the same manner as in example 1 except that 85 parts by weight of a resin (A-4) (product name ウルトラセン 540, manufactured by Tosoh corporation, Inc.) having a vinyl acetate content of 10%, a melt mass flow rate of 3.0g/10 min, and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 6.1 was blended in place of 85 parts by weight of the ethylene-vinyl acetate copolymer (A-1).

The evaluation results of the obtained resin composition and film for a covering material are shown in table 2. The obtained film for a lid material had poor adhesive strength and sealing strength.

Comparative example 3

A resin composition and a film for a covering material were obtained in the same manner as in example 1 except that the blending ratio of the ethylene-vinyl acetate copolymer (A-1) was changed to 50 parts by weight and the blending ratio of the tackifier resin (B-1) was changed to 50 parts by weight.

The evaluation results of the obtained resin composition and film for a covering material are shown in table 2. The obtained film for a lid material had poor sealing strength.

Comparative example 4

An adhesive for sealing and a film for a lid were obtained in the same manner as in example 1 except that the blending ratio of the ethylene-vinyl acetate copolymer (a-1) was changed to 97 parts by weight and the blending ratio of the tackifier resin (B-1) was changed to 3 parts by weight.

The evaluation results of the obtained sealing adhesive and lid film are shown in table 2. The obtained film for a lid material had poor adhesive strength and sealing strength.

Comparative example 5

A resin composition and a film for a covering material were obtained in the same manner as in example 1 except that 85 parts by weight of an ethylene-vinyl acetate copolymer (A-5) (product name ウルトラセン 537, manufactured by Tosoh corporation) having a vinyl acetate content of 5.5%, a melt mass flow rate of 8.5g/10 min, and a ratio Qw of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 5.8 was blended in place of 85 parts by weight of the ethylene-vinyl acetate copolymer (A-1).