JPS6356066B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a film-like laminate, and more particularly to a film-like laminate that has excellent heat-sealability, blocking resistance, and oil resistance, and can be easily opened when used as a lid for a container. Plastic films, especially unstretched films or sheets of polyethylene terephthalate (hereinafter referred to as PET) (hereinafter simply referred to as films), have excellent transparency, safety and hygiene properties, and are easy to thermoform, so they are used in foods and beverages. It is widely used as a packaging material. For example, containers thermoformed from PET film have been widely used in recent years as containers for foods such as margarine or containers for beverages such as sake. The lids of these containers are made of PET film or aluminum foil coated with an adhesive, and the lid material and the container body are usually bonded together by thermal bonding (hereinafter referred to as heat sealing). Containers manufactured in this way require the lid to be removed when taking out the contents, but the lid material of the containers currently on the market is difficult to peel off from the container, so for example, if the lid is made of aluminum foil, the lid must be torn off. Another disadvantage of PET film is that the contents must be removed by cutting off the lid with a cutter. As a method to improve these drawbacks, improvements in the adhesive applied to the lid material have been widely studied, but none has been found to be satisfactory. For example, if the container body and lid material are easily peeled off (hereinafter referred to as "easy open"), the adhesion between the lid materials used for heat sealing (hereinafter referred to as "blocking") may be too strong, resulting in problems in handling. Heat-sealing conditions may be too narrow and stable adhesion may be difficult (hereinafter referred to as heat-sealability), or depending on the contents (especially oil-based contents), adhesive strength may decrease due to penetration into the sealing area (hereinafter referred to as heat-sealability). They often have new drawbacks, such as oil resistance (described as oil resistance). As a result of repeated studies on a lid material that has excellent heat-sealing properties, anti-blocking properties, oil resistance, and easy-open properties, the present inventor found that a specific polyester resin containing a small proportion of a polar polyolefin resin has the above-mentioned properties. The present invention has been achieved based on the discovery that a film-like laminate that satisfies the above requirements and is laminated onto a film-like material is particularly useful as a lid material. That is, the present invention has an intrinsic viscosity of 0.5 or more and a softening point of 80 to 180°C.
The present invention relates to a film-like laminate in which a thin layer of a composition containing a polyester resin and a polar polyolefin resin in an amount of 5 to 50% by weight based on the polyester resin is laminated on at least one surface of a film-like object. In the present invention, the thin layer of the composition laminated on at least one surface of the film material acts as a thermal adhesive, and in particular, the polyester resin constituting the composition primarily acts as an adhesive. This polyester resin has an intrinsic viscosity of 0.5 or more,
It has a softening point of 80 to 180°C, preferably terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, etc. Aromatic dicarboxylic acid and part of it contains sodium sulfonate
Introduced groups: hexahydroterephthalic acid,
Alicyclic dicarboxylic acids such as hexahydroisophthalic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, etc.; oxyacids such as p-β-hydroxyethoxybenzoic acid, ε-oxycaproic acid, etc. one or more other difunctional carboxylic acids and ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol,
1,1-cyclohexane dimethylol, 1,4-
Cyclohexane dimethylol, 2,2-bis(4′-βhydroxyethoxyphenyl)propane,
It is a copolyester comprising one or more other glycols such as bis(4'-β-hydroxyethoxyphenyl)sulfonic acid. If the intrinsic viscosity of the polyester resin is lower than 0.5, the adhesive strength with the container body during heat sealing, for example, becomes weak, which is not preferable. Although there is no particular upper limit to the intrinsic viscosity, if it is too high, production becomes difficult, so it is preferable to take this point into consideration when determining the intrinsic viscosity of the polymer used. Furthermore, if the softening point of the polyester resin is higher than 80°C, there are disadvantages such as a narrow range of heat sealing and difficulty in dissolving in a solvent when coating or laminating a film-like material, which is not preferable. In the present invention, the polar polyolefin resin to be mixed with the polyester resin includes, for example, isotactic polypropylene into which a halogen element is introduced, and chlorinated polypropylene mainly consisting of components represented by the following formula is particularly preferred. In the case of this chlorinated polypropylene, the chlorination rate is
A content of 20 to 40% by weight is preferable because it has excellent solubility and uniform dispersibility with the polyester resin. This polar polyolefin resin improves the easy-open properties, blocking resistance, and oil resistance while maintaining the adhesive properties of the polyester resin, and is used in an amount of 5 to 50% by weight based on the polyester resin. If the blending ratio is less than 5% by weight, it is difficult to obtain the effects of improving easy-open properties and blocking properties, and if it is more than 50% by weight, the adhesive strength will be too weak and the oil resistance will decrease, which is not preferred. The polyester resin and the polar polyolefin resin may be mixed by any method as long as they are mixed uniformly, such as by dissolving and/or dispersing both in a solvent such as toluene or methyl ethyl ketone, or by melting. A method is used in which the two are mixed in the same state. In the present invention, the above-mentioned composition is laminated on at least one surface of a film-like object, and the lamination method includes, for example, coating the composition dissolved in a solvent on at least one surface of the film-like object, and then
Examples include a method in which the solvent is removed by evaporation, a method in which a molten composition is applied and then cooled and solidified, and a coextrusion method. The thickness of the composition layer (adhesive layer) may normally be selected so that the adhesive strength is appropriate, and is preferably, for example, 50 μm or less, particularly around 10 μm. The film-like material on which the adhesive layer is laminated in the present invention is
Any material may be used as long as it can be laminated, but preferably a thermoplastic resin film such as polyester or a metal foil such as aluminum foil is used. In the case of polyester film, polyester containing ethylene terephthalate as the main repeating unit is preferred, but other polyesters such as polybutylene terephthalate and polyarylate may also be added to this.
Particularly preferred is a non-oriented film in which the components are mixed within the range of % by weight. The preferred thickness of the film-like material varies depending on the material of which the film is made, but it should be such that the temperature of the sealing surface rises to a temperature that produces adhesive strength in a short period of time (for example, within 3 seconds) when heat sealing is performed. For example, in the case of polyester film, it is preferably 300μ or less, and in the case of aluminum foil, it is 100μ
It is preferable that it is below. The polyester film is preferably a polyethylene terephthalate (PET) film,
A part of the terephthalic acid component of polyethylene terephthalate can be added to an aromatic dicarboxylic acid such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid; Alicyclic dicarboxylic acids such as hydroterephthalic acid, hexahydroisophthalic acid, etc.; Aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, etc.; p-β-hydroxyethoxybenzoic acid, ε-oxycaproic acid, etc. one or more other difunctional carboxylic acids such as oxyacids, and/or a portion of the ethylene glycol component, such as trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol , 1,1-cyclohexane dimethylol, 1,4-cyclohexane dimethylol, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4'-β
Copolymerization with substitution within 15 mol%, preferably within 5 mol%, of other glycols such as hydroxyethoxyphenyl) sulfonic acid and one or more polyfunctional compounds of their functional derivatives. It may also be a film of a coated copolymer. Further, as the polybutylene terephthalate, a homopolymer of polybutylene terephthalate (polytetramethylene terephthalate) and a modified polybutylene terephthalate can be used. Furthermore, polyarylates include, for example, polyesters prepared from mixtures of bisphenols, especially bisphenol A, and aromatic dicarboxylic acids, especially terephthalic acid and isophthalic acid, as well as ester-forming derivatives thereof. Commercially available products can be used as these. The film-like laminate of the present invention thus obtained has excellent heat-sealing properties, blocking resistance, oil resistance, etc., and can be used particularly as a film for lid materials that can be easily opened. The present invention will be explained in detail with reference to Examples below. The conditions for measuring the main characteristic values are as follows. Intrinsic viscosity (IV): Measured at 35°C using O-chlorophenol as a solvent. Softening point (sp): Based on Vikatsuto softening point measurement method. Easy openability: A sample cut to a width of 15 mm is stacked on the sample to be adhered so that the adhesive layer is in the middle, and heat-sealed at a predetermined temperature and pressure for a predetermined time using a heat sealer with a 5 mm-wide heating part, until the sealed part is at room temperature. After it has cooled down to
Adhesive strength was measured. If the sealing temperature range in the range where the adhesive strength is 0.5 to 2.0Kg/15mm is 20℃ or higher...very good◎ If it is 10 to 20℃...good 〇 If it is 5 to 10℃...slightly poor △ If it is 5℃ or less In this case, it was marked as defective. Blocking resistance: Width 50mm, length made of unstretched PET film with a wall thickness of 125μ and an adhesive layer applied on one side.
A 300mm sample is rolled with a winding diameter of 6 to 10mm.
Roll it up, fix the outside with a rubber band, and store it at 20℃ for 12 minutes.
Leave it for a while. After standing still, the rubber band was removed and the condition was evaluated as follows.

[Front] The surface slides well and the edges align smoothly.
Oil resistance: A heat-sealed adhesive sample was immersed in edible oil at 20°C for 1 hour in the same manner as for measuring easy-open properties, and then the adhesive strength was measured and evaluated according to the following criteria. Adhesion strength decrease rate is 5% or less
…◎ Extremely good Adhesion strength decrease rate is 5-10%
…〇 Good 〃 10-30%
…△ Fairly good 〃 30%~
...× Poor Examples 1 to 8 and Comparative Examples 1 to 4 70 mol% of terephthalic acid and 30 mol% of sebacic acid as acid components, 55 mol% of ethylene glycol and neopentylene glycol as glycol components
30 parts by weight of modified polyester (polyester adhesive) copolymerized with 45 mol% of IV = 0.70, sp 123°C, and 80 parts by weight of toluene and methyl ethyl ketone.
Dissolved in a mixed solvent consisting of 20% by weight, and further
The modifier shown in 1 was added. The obtained mixed solution was applied to a thickness of approximately 10μ on one side of a non-oriented transparent PET film with a thickness of 125μ, IV = 0.60, sp = 255℃, and the solvent was removed by evaporation at 80℃ to form an adhesive. A laminated PET film was obtained with the layers coated on one side. This laminated PET film is cut into 15mm width,
A non-oriented transparent PET sheet with a wall thickness of 600 μm and a width of 15 mm was heat-sealed using a heat sealer having a heating section of 5 mm width while changing the heating temperature from 160° C. to 230° C. in 5° C. increments. The heat sealing time was about 1 second. The sample thus obtained was evaluated by the method described above. The evaluation results are shown in Table-1. In addition, in place of the above polyester adhesive, 55 mol% of isophthalic acid and 45 mol% of terephthalic acid were copolymerized as acid components, and 55 mol% of neopentylene glycol and 45 mol% of ethylene glycol were copolymerized as glycol components, IV=0.55. , sp=165℃
modified polyester (polyester adhesive)
) was used, but the same test as above was conducted. The results are shown in Table-1.

【table】

[Table] Example 9 and Comparative Example 5 The same procedure as Example 1 and Comparative Example 3 was carried out, except that aluminum foil with a wall thickness of 40 μm was used instead of the non-oriented transparent polyester film with a thickness of 125 μm, and further evaluation was performed. did. The results obtained were similar to Example 1 and Comparative Example 3. Example 10 and Comparative Example 6 In place of the 125μ thick polyester film, a non-oriented transparent film made of polyester prepared by adding 10% by weight of polybutylene terephthalate of IV=1.0 to the PET of Example 1 was used. 1 and Comparative Example 3, and further evaluation was carried out. The results obtained were similar to Example 1 and Comparative Example 3. As is clear from the above examples, the film-like laminate of the present invention has good heat-sealability, oil resistance, and blocking resistance, and is excellent as a lid material that can be opened easily.

Claims (1)

[Claims] 1. Intrinsic viscosity is 0.5 or more, and softening point is 80 to 180.
A film-like laminate obtained by laminating on at least one surface of a film-like material a thin layer of a composition containing a polyester resin having a temperature of 10.degree. 2. The polar polyolefin resin is chlorinated polyprolene and has a chlorine content of 20 to 40% by weight,
The laminate according to claim 1, having a melting point of 80 to 105°C. 3 The film-like material has an intrinsic viscosity of 0.5 to 1 and a softening point.
Claim 1, characterized in that it is a substantially non-oriented film made mainly of polyester whose main repeating unit is ethylene terephthalate at a temperature of 200°C or higher, or an aluminum foil.
Laminated body as described in section. 4 Substantially non-oriented film has an intrinsic viscosity of 0.5~
1. A film comprising a composition comprising a polyester whose main repeating unit is ethylene terephthalate having a softening point of 200°C or higher and 30% by weight or less of polybutylene terephthalate based on the polyester. The laminate according to scope 3.