JP2002226642A - Thermoplastic resin composition and sealing material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a sealing material which has an excellent easy-to-open performance with polyester or polypropylene, an antistatic effect in a low moisture atmosphere and a superior continuance of the effect. SOLUTION: The thermoplastic resin composition consists of (A) an ethylene- vinyl ester copolymer, (B) a low-crystalline or amorphous ethylene-α-olefin copolymer and (C) a potassium ion ionomer of an ethylene-unsaturated carboxylic acid copolymer containing a compound having three or more hydroxy groups in a molecule and a molecular weight of 400 or less. This composition is suited for a sealing material which has an excellent easy-to-open performance with polyester or polypropylene, an antistatic effect in a low moisture atmosphere and a superior continuance of the effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition which is semi-permanent and has excellent antistatic properties under low humidity, and a sealing material provided with a heat-sealing layer comprising the composition. The present invention relates to a sealing material having excellent openability with polyester such as terephthalate and polyethylene naphthalate and polypropylene.

[0002]

BACKGROUND OF THE INVENTION As containers for various foods and beverages and pharmaceuticals, thermoplastic resin containers sealed with a seal material having an easily-openable heat-sealing layer are widely used. Such a sealing material is required to have a wide heat-sealing temperature range, a suitable sealing strength (peeling strength), and a function that can be easily opened. Since the required sealing strength varies depending on the material and size of the container, the article to be packaged, and the like, various sealing materials have been proposed and used.

Incidentally, such a sealing material may be required to have an antistatic property on the film surface depending on the use, and therefore, an antistatic agent is blended. However, if an antistatic agent is blended with the sealing material, the antistatic agent bleeds out to the surface of the sealing material and the sealing strength is reduced, or a fog or the like is deposited on a die lip during film formation, and the production line is frequently stopped. Had to be cleaned.

As a method for solving such a problem, it has been proposed that a laminated film using a composition comprising a potassium ionomer is excellent in non-charging properties (Japanese Patent Application Laid-Open No. Hei 8-267671). However, such a laminated film is not versatile as a sealing material, and has a problem in that it has poor sealing properties with polyester, polypropylene, and the like.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present inventors have
Excellent openability with polyester and polypropylene,
Various studies were conducted to develop a sealing material having an antistatic effect even at low humidity and having excellent durability of the antistatic effect.

[0006]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention relates to an ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α
-Potassium ion ionomer (C) of an olefin copolymer (B) and an ethylene / unsaturated carboxylic acid copolymer containing a compound having a molecular weight of 400 or less and having three or more hydroxyl groups in a molecule (hereinafter referred to as "ionomer (C)") The seal has excellent openability with polyester, polypropylene, etc., has an antistatic effect even at low humidity, and has excellent durability of the antistatic effect. The present invention relates to a thermoplastic resin composition suitable as a material. More preferably, the ethylene / vinyl ester copolymer (A) in the thermoplastic resin composition is 20 to 60% by weight,
20 to 60% by weight of a low crystalline or amorphous ethylene / α-olefin copolymer (B) and an ionomer (C)
Is in the range of 1 to 40% by weight.

Another embodiment of the present invention relates to an ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B) and an ionomer (C), The present invention relates to a thermoplastic resin composition containing the imparting agent (D).

[0008] The present invention also relates to a method for producing a composition comprising an ethylene / vinyl ester copolymer (A), a low-crystalline or amorphous ethylene / α-olefin copolymer (B), The present invention relates to a sealing material provided with a heat sealing layer made of a thermoplastic resin composition with an ionomer (C).

[0009]

DETAILED DESCRIPTION OF THE INVENTION Ethylene vinyl ester copolymer
(A) The ethylene / vinyl ester copolymer (A) constituting the thermoplastic resin composition of the present invention is a copolymer of ethylene and a vinyl ester such as vinyl acetate or vinyl propionate. The content of vinyl ester present in the coalescence is usually in the range of 3 to 30% by weight, preferably 5 to 15% by weight. When the vinyl ester content is within this range, the balance between heat seal strength and easy peelability is kept good, and the composition has the heat resistance required for filling foods, which is advantageous. The copolymer has a melt flow rate (MFR) of usually 1 to 40, preferably 1.5 to 30 (g / 10) measured according to JIS 6730.
Is desirable in order to obtain good extrudability and sufficient mechanical strength when used as a packaging film. This ethylene / vinyl ester copolymer (A) has an effect of imparting low-temperature heat sealability when used as a heat-sealing layer.

Low-crystalline or amorphous ethylene α-
Olefin copolymer (B) Low-crystalline or amorphous ethylene / α-olefin copolymer (B) constituting the thermoplastic resin composition of the present invention
Is a random copolymer of ethylene and propylene, 1-butene, 11-pentene, 1-hexene, 4-methyl-1-pentene, α-olefin having 3 to 10 carbon atoms such as 1-octene, usually X-ray Is usually 30% or less, preferably 25% or less, and the density is 0.86 to 0.92.
g / cm ³ , preferably 0.87 to 0.91 g / cm ³
3, MFR (ASTM D1238 load 2160g,
(Temperature 190 ° C.) is 0.2 to 30 g / 10 min, preferably 1 to 10 g / 10 min, and the melting point by DSC is 100 ° C. or lower, preferably 80 ° C. or lower.

A molecular weight of 40 having three or more hydroxyl groups in the molecule
Ethylene / unsaturated carboxylic acid copolymer containing 0 or less compounds
Combined potassium ion ionomer (C) The potassium ion ionomer of the ethylene / unsaturated carboxylic acid copolymer constituting the ionomer (C) constituting the thermoplastic resin composition of the present invention is an ethylene / unsaturated carboxylic acid copolymer Is neutralized with potassium ions, preferably at least 60%, particularly preferably at least 70%, and the total amount of potassium ions is
It is preferably in the range of 0.4 to 4 mol, particularly 0.6 to 2 mol, per kg in consideration of non-charging properties and film properties. Of course, such a potassium ionomer can also be produced, for example, by saponifying an ethylene / unsaturated carboxylic acid ester copolymer. MF of such a potassium ionomer
R (190 ° C., 2160 g load) is usually 0.01 to 1
000 g / 10 min, preferably 0.1-100 g / 10
In the range of minutes.

The ethylene / unsaturated carboxylic acid copolymer serving as the base polymer of the potassium ionomer is obtained by copolymerizing ethylene and an unsaturated carboxylic acid, and optionally other monomer components. Ethylene is 60 to 90% by weight, preferably 70 to 88% by weight, and unsaturated carboxylic acid is 10 to 40% by weight, preferably 12 to 3% by weight.
0% by weight and 0 to 30% by weight, preferably 0 to 20% by weight, of other monomer components are randomly copolymerized. Along with such a random copolymer,
Similar random copolymers having a higher ethylene content than the above and therefore a lower unsaturated carboxylic acid content than the above may be used in combination.

Examples of such unsaturated carboxylic acids include acrylic acid, methacrylic acid, fumaric acid, monomethyl maleate, monoethyl maleate, and maleic anhydride, and acrylic acid or methacrylic acid is particularly desirable. Other optional monomer components include unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. And methyl methacrylate and isobutyl methacrylate, and vinyl esters such as vinyl acetate and vinyl propionate. Such a copolymer can be obtained by subjecting each polymerization component to radical copolymerization under high temperature and high pressure in the same manner as in high-pressure polyethylene.

A compound having a molecular weight of 400 or less and having three or more hydroxyl groups in the molecule contained in the potassium ion ionomer of the ethylene / unsaturated carboxylic acid copolymer may be a compound composed of only carbon, hydrogen and oxygen. It may also contain a heteroatom such as nitrogen in addition to carbon, hydrogen and oxygen. These have a molecular weight of 4
00 or less, preferably 80 to 300, and may be liquid or solid at room temperature. Molecular weight 400
The effect of improvement is small even if a material exceeding the above is used.

Specific examples of such compounds include glycerin, diglycerin, trimethylolpropane,
1,1-tris (hydroxymethyl) ethane, 2,2-
Di (hydroxymethyl) -1,3-propanediol,
Sorbitol, 1,3,5-trihydroxybenzene,
1,3,5-trihydroxybenzoic acid, tris (hydroxymethyl) aminopropane, N, N, N ′, N′-tetrakis (2-hydroxyethyl) ethylenediamine,
N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine and the like can be exemplified. Among these, it is most preferable to use an aliphatic polyhydric alcohol such as glycerin or trimethylolpropane.

The amount of the compound having a molecular weight of 400 or less having three or more hydroxyl groups in the molecule is usually 0.1 to 3 per 100 parts by weight of the potassium ionomer component.
0 parts by weight, preferably 1 to 20 parts by weight. When the amount of the compound having a molecular weight of 400 or less having three or more hydroxyl groups in the molecule is less than the above range, the effect of improving the non-charging property may not be sufficient. On the other hand, if the amount of the compound having a molecular weight of 400 or less having three or more hydroxyl groups in the molecule is more than the above range, the preparation of the compound becomes difficult, and the surface contamination by bleeding is unfavorable.

Tackifier (D) As the tackifier (D) constituting the thermoplastic resin composition of the present invention, coumarone-indene resin, p-tert-
Phenolic resins such as butylphenol / acetylene resin, phenol / formaldehyde resin, terpene / phenolic resin and xylene / formaldehyde resin, β
-Pinene resin, α-pinene resin, dipentene base resin and styrene-modified terpene resin, terpene resins such as synthetic polyterpene resin, terpene resin having no polar group,
Petroleum-based such as aromatic hydrocarbon resins, aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / alicyclic petroleum resins, aliphatic / aromatic petroleum resins, and hydrogenated hydrocarbon resins Rosins such as hydrocarbon resins, rosin pentaerythritol ester, rosin glycerol ester, hydrogenated rosin, hydrogenated rosin pentaerythritol ester, hydrogenated rosin methyl ester, and hydrogenated rosin triethylene glycol ester Derivatives and the like.

Of these, terpene resins having no polar group and petroleum hydrocarbon resins having no polar group are preferred because of their excellent thermal stability, and are further hydrogenated, preferably 80% or more, particularly 95% or more. The added petroleum hydrocarbon resin having no polar group is preferable because it is excellent in workability in that it does not generate deterioration products such as fish eyes (FE) and has excellent stability in forming a film with beautiful appearance.

Thermoplastic Resin Composition The thermoplastic resin composition of the present invention comprises an ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B), and an ionomer. (C), preferably in the thermoplastic resin composition, wherein the ethylene / vinyl ester copolymer (A) is 20
-60% by weight, more preferably 25-40% by weight, low crystalline or amorphous ethylene / α-olefin copolymer (B) is 20-60% by weight, more preferably 25-40% by weight, and The ionomer (C) is in the range of 1 to 40% by weight, more preferably 10 to 30% by weight.

[0020] Ethylene vinyl ester copolymer (A)
If the content is less than 20% by weight, heat seal strength may not be sufficiently exhibited. On the other hand, if it exceeds 60% by weight, heat resistance such as appropriate boiling may be deteriorated. If the ethylene / α-olefin copolymer (B) is less than 20% by weight, the low-temperature heat
Sufficient performance may not be exhibited in terms of sealability and heat seal strength. On the other hand, if it exceeds 60% by weight, heat seal strength may not be sufficiently exhibited. If the amount of the ionomer (C) is less than 20% by weight, a sufficient antistatic effect may not be exhibited.
There is a possibility that the sealing strength cannot be sufficiently exhibited.

The thermoplastic resin composition of the present invention contains a tackifier (D) in addition to the above three components, preferably from 3 to 3
0% by weight, more preferably 10 to 25% by weight
When it is contained by weight, the stability of heat seal strength as an easily-openable sealant is improved.

The thermoplastic resin composition of the present invention comprises the above ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B),
Ionomer (C) and, if necessary, tackifier (D)
In the above range by a Henschel mixer, a V-blender, a ribbon blender, a tumbler mixer, or the like, and a method of melt-kneading with a single-screw extruder, a multi-screw extruder, a Banbury mixer, or the like after mixing.

The thermoplastic resin composition of the present invention comprises an ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B), an ionomer (C) and Separately to the tackifier (D),
Or, when producing the composition, as long as the object of the present invention is not impaired, a commonly used antioxidant, weather stabilizer,
Additives such as an antistatic agent and an antifogging agent can be added as needed. In particular, by blending an anti-blocking agent and a slip agent, processability and workability during extrusion, lamination, packaging, and the like can be improved.

As the anti-blocking agent, silica,
Examples include inorganic powders such as talc, clay, and zeolite. As slip agents, fatty acid amides such as stearic acid amide, oleic acid amide, palmitic acid amide, erucic acid amide; stearic acid, oleic acid,
Fatty acid bisamides such as methylene bisamide and ethylene bisamide of fatty acids such as erucic acid; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; hydrogenated castor oil; fatty acid metal salts; It is preferable that these antiblocking agents and slip agents are incorporated into the thermoplastic resin composition within a range that does not cause a problem in performance.

Substrate (E) The substrate (E) laminated with the sealing material of the present invention may be made of various materials usually used as packaging materials, for example, polyethylene film, polypropylene film, polybutene film and polymethylpentene. Polyolefin film such as film, polyester film such as polyethylene terephthalate film and polycarbonate film, nylon film, polystyrene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl alcohol copolymer film, polymethyl methacrylate film And a film made of a thermoplastic resin such as an ethylene / vinyl acetate copolymer film, an aluminum foil, and paper. The substrate made of such a thermoplastic resin film may be unstretched or a uniaxially or biaxially stretched film. Of course, the base material may be one layer or two or more layers.

Sealing Material The sealing material of the present invention is a laminate in which a heat sealing layer made of the above-mentioned thermoplastic resin composition is laminated on at least one surface of the substrate (E). As a method for producing such a sealing material, various known methods, for example, T-
A method of forming a film in advance using a die film forming machine, an inflation film forming machine or the like, and then bonding the film to the substrate (E) with or without an adhesive, the substrate (E)
Extruding and laminating a thermoplastic resin composition using an extruder, a method of coextruding a thermoplastic resin as a base material and a thermoplastic resin composition as a heat-fusible layer to form a sealing material, and the like. Can be illustrated.

The thickness of the heat-sealing layer made of the thermoplastic resin composition in the sealing material is usually in the range of 3 to 1000 μm, preferably 5 to 100 μm. Further, by using a thermoplastic resin composition containing no ionomer (C) as an antistatic agent as a reinforcing layer of the heat fusion layer, the thickness of the heat fusion layer can be reduced to about 2 μm or more. In that case, the thickness of the reinforcing layer is usually in the range of 18 to 998 μm.
The reinforcing layer may be a single layer or two or more layers.

[0028]

The thermoplastic resin composition of the present invention, when used as a heat-sealing layer, has excellent openability with polyester and polypropylene, has an antistatic effect even at low humidity,
Moreover, it is excellent in persistence of the antistatic effect, and can be suitably used as a heat sealing layer of a sealing material. In addition, when the heat-sealing layer is obtained, it is possible to reduce the contamination of the cooling roll at the time of melt-extrusion and film-forming process, which has been caused mainly by the antistatic agent. Also in the case of laminating the layer with another material as a base material, the dirt on the roll of the processing machine can be reduced, so that the workability of the forming process can be improved. Furthermore, the resulting film made of the thermoplastic resin composition has a small amount of bleed-out of the antistatic agent or the like on the film surface. There is no reduction, there is no dissipation by heat of the antistatic agent during processing,
Processing can be performed without lowering the antistatic property.

Further, the sealing material of the present invention is used as a lid material for containers such as toner, a lid material for electronic parts, etc.
It can be used as a packaging material in all fields including foods, daily necessities, etc., in applications requiring antistatic properties on the film surface, and in a well-balanced non-static property and heat seal functionality.

[0030]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.

The characteristic values in Examples and Comparative Examples were measured by the following methods. (1) Surface resistivity (change over time) 10 × 10c from the obtained heat-sealed film
m, and cut out in a 40 ° C. oven for 3 days a day.
After aging treatment for 0 days and 90 days, it was taken out of the oven and left for 24 hours in an atmosphere of 20 ° C. and a relative humidity of 65%. R1
2704), the surface resistivity was measured. (Humidity dependency) 10 × 10
cm of a test piece, and a relative humidity of 40 ° C.
%, After aging treatment in an oven with an atmosphere of 35% for 1 day, taken out of the oven, and performed at 30 ° C. in an atmosphere of 60%, 45%, and 35%, which is the same as the relative humidity of the aging treatment. Was used to measure the surface specific resistance. (2) Non-Chargeability An A4 size test piece was cut out from the obtained heat-sealing film and subjected to aging treatment in an oven at 40 ° C. for 1, 30, and 90 days. It was left at a relative humidity of 60% for 24 hours. After holding the treated test piece with both hands and rubbing it 10 times with the head, the test piece was placed on a table, approached to the tobacco ash, and the distance at which the ash was drawn to the test piece was measured and evaluated. A test piece to which ash did not adhere even when approached to 0 cm was rated as ◎, a test piece to which ash was slightly attached when approached to 0 to 1 cm, and a test piece to which ash adhered when approached to 6 cm. (3) Heat sealing property: The obtained heat-sealed film and the anchor-coated surface of a biaxially oriented polyethylene terephthalate film (PET) having a thickness of 12 μm were formed using a high-pressure low-density polyethylene having a thickness of 20 μm. A laminated film was prepared by an extrusion lamination method. Next, the heat-sealing film surface of the obtained laminated film and a polypropylene sheet (East Cello PP sheet TT) surface having a thickness of 300 μm are overlapped, and a predetermined heat sealer having a sealer of 5 mm is used. The mixture was heat-sealed at a pressure of 0.2 MPa at a temperature for 1 second and allowed to cool. From this, a test piece having a width of 15 mm was cut out and the heat-sealed portion was peeled off at a crosshead speed of 500 mm / min.

The raw materials used in this example are as follows. (1) Ethylene / vinyl acetate copolymer (EVA): vinyl acetate content 10% by weight, MFR 9 g / 10 min, melting point 94
° C (2) Ethylene / 1-butene copolymer (EBR): 1-
Butene content: 10% by weight, density: 0.88 g / cm ³ , melting point: 68 ° C, MFR: 4.0 g / 10 minutes (3) Aliphatic hydrocarbon resin: Arakawa Chemical Co., Ltd. product (brand name: Alcon), softening point by ring and ball method 115 ° C. (4) Ethylene / acrylic acid copolymer potassium ionomer resin composition containing 10% by weight of glycerin (ionomer composition) Base polymer: ethylene / acrylic acid copolymer (acrylic acid content 21% by weight) Metal cation source: potassium Neutralization degree: 80 mol% Metal cation content: 2.3 mol / kg ionomer MFR: 0.6 g / 10 min Glycerin (molecular weight 92)

Example 1 EVA: 36% by weight, EBR: 36% by weight, aliphatic hydrocarbon resin: 18% by weight, and ionomer composition: 10
The thermoplastic composition (heat-sealing layer) in which the weight% was dry blended was supplied to an extruder, and a heat-sealing film was obtained by a T-die method. The thickness of the film was 30 μm. Table 1 shows the evaluation results of the obtained heat-sealing films.

Example 2 EVA: 34% by weight, EBR: 34% by weight, aliphatic hydrocarbon resin: 17% by weight, and ionomer composition: 15
The thermoplastic composition (heat-sealing layer) in which the weight% was dry blended was supplied to an extruder, and a heat-sealing film was obtained by a T-die method. The thickness of the film was 30 μm. Table 1 shows the evaluation results of the obtained heat-sealing films.

Example 3 EVA: 32% by weight, EBR: 32% by weight, aliphatic hydrocarbon resin: 16% by weight, and ionomer composition: 20
The thermoplastic composition (heat-sealing layer) in which the weight% was dry blended was supplied to an extruder, and a heat-sealing film was obtained by a T-die method. The thickness of the film was 30 μm. Table 1 shows the evaluation results of the obtained heat-sealing films.

Example 4 A thermoplastic composition (heat-sealing layer) obtained by dry-blending 40% by weight of EVA, 40% by weight of EBR and 20% by weight of an ionomer composition was supplied to an extruder and subjected to a T-die method. Thus, a heat fusion film was obtained. The thickness of the film was 30 μm. Table 1 shows the evaluation results of the obtained heat-sealing films.

Comparative Example 1 A thermoplastic composition (heat-sealing layer) obtained by dry-blending 40% by weight of EVA, 40% by weight of EBR and 20% by weight of an aliphatic hydrocarbon resin was supplied to an extruder. A heat-sealed film was obtained by a die method. The thickness of the film is 30 μm
Met. Table 1 shows the evaluation results of the obtained heat-sealing films.

[0038]

【table 1】

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C09K 3/10 C09K 3/10 Z R 3/16 102 3/16 102J F term (reference) 4F100 AH02 AK06 AK42 AK63B AK68B AK70B AL01B AL05B AT00A BA02 BA07 CA16B EH23 EJ65 GB15 JG03 JL12 JL12B JL14 4H017 AA04 AB01 AB07 AB10 AB17 AC02 AC10 AC17 AD06 AE05 4J002 AF00Z AF02Z BA00Z BB05Z06 BB06ZB00 CC BB06ZB CC

Claims (8)

[Claims] 1. An ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B) and a compound having a molecular weight of 400 or less and having three or more hydroxyl groups in the molecule. Ionomer of ethylene-unsaturated carboxylic acid copolymer containing carbon (C)
A thermoplastic resin composition comprising: 2. The thermoplastic resin composition according to claim 1, wherein
20 to 60% by weight of the vinyl ester copolymer (A), 20 to 60% by weight of the low crystalline or amorphous ethylene / α-olefin copolymer (B), and 3 hydroxyl groups in the molecule.
Ethylene containing compounds having a molecular weight of 400 or less
The thermoplastic resin composition according to claim 1, wherein the potassium ionomer (C) of the unsaturated carboxylic acid copolymer is in the range of 1 to 40% by weight. 3. An ethylene / vinyl ester copolymer (A)
Is an ethylene / vinyl acetate copolymer having a vinyl acetate content of 3 to 25% by weight. 4. A molecular weight of 40 having at least three hydroxyl groups in the molecule.
The thermoplastic resin composition according to claim 1 or 2, wherein the potassium ion ionomer (C) of the ethylene / unsaturated carboxylic acid copolymer containing 0 or less compounds has a degree of neutralization by potassium ions of 70 mol% or more. 5. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin composition further contains a tackifier (D). 6. The thermoplastic resin composition according to claim 5, wherein the content of the tackifier (D) in the thermoplastic resin composition is 3 to 30% by weight. 7. A base material (E) having at least one side with an ethylene / vinyl ester copolymer (A), a low crystalline or amorphous ethylene / α-olefin copolymer (B) and a hydroxyl group in the molecule. Characterized in that it has a heat-sealing layer comprising a thermoplastic resin composition with a potassium ionomer (C) of an ethylene / unsaturated carboxylic acid copolymer containing at least three compounds having a molecular weight of 400 or less. Wood. 8. The sealing material according to claim 7, wherein the thermoplastic resin composition constituting the heat-sealing layer further contains a tackifier (D).