JPH0542642A - Lid material - Google Patents

Abstract

PURPOSE:To lower temperature of thermal fusion onto a container and besides to quicken sealing speed by a method wherein an easily unsealable resin layer of a lid material is so constructed that a specific composition polyethyleneterephthalate resin and a polybutyleneterephthalate resin are mixed by a specific proportion. CONSTITUTION:A container body 6 made of polyethyleneterephthalate is sealed by fixing by thermal fusion of an easily unsealable resin layer 4 of a lid material 2 to a surface. In that case, a polyethyleneterephthalate resin being a copolymer of dicarboxylic acid as an acid component having terephthalic acid mainly and a mixture, as an alcohol component, of 40-80wt.% ethylene glycol and 60-20wt.% 1,4-cyclohexanedimethanol is contained by 80-50wt.% in the easily unsealable resin layer 4. Further, a polybutyleneterephthalate resin being a polymer of dicarboxylic acid as an acid component having terephthalic acid by 90mol% and 1,4-butanediol as an alcohol component, is contained by 20-50wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid material, and more particularly, to sealing a container formed of polyethylene terephthalate,
The present invention also relates to a lid material that can be easily opened.

[0002]

2. Description of the Related Art Conventionally, a package has been widely used in which a container formed by deep-drawing a thermoplastic resin such as polyethylene terephthalate is filled with contents such as food and sealed with a flexible lid material. In such a package, it is required that the lid material can be easily peeled off by hand when the contents are taken out from the container, that is, easy opening. Therefore, as the lid member, a flexible base material having an easily openable resin layer formed on one surface thereof is used, and the easily openable resin layer is heat-sealed to the flange of the container opening or the like. Thus, the container was sealed. The easy-open form mainly includes a cohesive failure type in which the easy-open resin is broken to open and a interface peeling type in which the interface peels. The cohesive failure type has hitherto been based on polypropylene and polyethylene (JP-A-57-7).
7465, etc.) were used. However, in these cases, the force required at the initial peeling of the lid material is large and it is difficult to open, the peeled surface is rough, and the appearance and texture are not good,
In addition, there is a problem that the amount of heat required for heat fusion is large and the sealing speed by the lid material cannot be increased. In order to solve such a problem as a lid material for a polyester container, it has been proposed to use a mixture of a polyethylene terephthalate resin and a polybutylene terephthalate resin as an easily openable resin (Japanese Patent Publication No. 63-57236).
issue).

[0003]

However, an easily-openable resin made of a mixture of the above-mentioned polyethylene terephthalate resin and polybutylene terephthalate resin is
There is a problem in that the film-forming property is poor, and the thickness of the easily-openable resin layer formed on the base material becomes uneven, so that the force required for peeling the lid material becomes uneven. In addition, the above-mentioned easy-open resin is still insufficient in heat fusion temperature as compared with other conventional easy-open resins, but is still insufficient, and deformation of the container occurs in heat fusion to the container, or a lid material. However, there was a problem that the sealing speed was slow.

The present invention was devised in view of the above-mentioned circumstances, and an object thereof is to provide a lid member having a low heat fusion temperature to a container and a high sealing speed.

[0005]

In order to achieve such an object, the present invention has an easily-openable resin layer on one surface of a base material, and a polyethylene terephthalate is used as a constituent material on the surface of a container. In the lid material for sealing the container by heat-sealing the easily-openable resin layer, the easily-openable resin layer comprises dicarboxylic acid as an acid component mainly composed of terephthalic acid and ethylene glycol as an alcohol component. Polyethylene terephthalate resin 80 to 50 wt which is a copolymer with a mixture of 40 to 80 wt% and 1,4-cyclohexanedimethanol 60 to 20 wt%
%, 50 to 90 mol% is terephthalic acid, and dicarboxylic acid as an acid component and 1,4-as an alcohol component.
It was configured to be formed by a resin mixture of 20 to 50 wt% of polybutylene terephthalate resin which is a polymer with butanediol.

[0006]

The lid member has a base material and an easy-opening resin layer formed on one surface of the base material. The easy-opening resin layer is made of polyethylene terephthalate resin 80 to 50 wt% and polybutylene terephthalate resin. The polyethylene terephthalate resin is formed of a resin mixture of 20 to 50 wt%, and the polyethylene terephthalate resin is a dicarboxylic acid mainly containing terephthalic acid and an ethylene glycol 4 as an alcohol component.
A copolymer with a mixture of 0 to 80 wt% and 1,4-cyclohexanedimethanol 60 to 20 wt%, and
The above polybutylene terephthalate resin is 50 to 90.
It is a polymer of a dicarboxylic acid as an acid component having a mole% of terephthalic acid and 1,4-butanediol as an alcohol component. Thereby, the thickness of the easy-open resin layer becomes uniform, and when the lid member is heat-sealed to the surface of the container formed by using polyethylene terephthalate as a constituent material through the easy-open resin layer, heat fusion is performed. The attachment temperature is lower than that of the conventional easily openable resin, the sealing speed of the container can be increased, and the container can be easily opened by peeling the lid material.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a package using an embodiment of the lid material of the present invention. In FIG. 1, a package 1 has a lid member 2 and a container 5 whose opening 7 is sealed by the lid member 2. The lid member 2 includes a base material 3 and an easily-openable resin layer 4 formed on one surface of the base material 3. Also,
The container 5 is formed by deep drawing, and the main body 6 and the main body 6 are formed.
And a flange portion 8 formed on the periphery of the upper end portion of the. Then, the lid member 2 is heat-sealed to the flange portion 8 so as to cover the opening portion 7 of the container 5 via the easy-open resin layer 4, so that the container 5 is sealed.

The base material 3 of the lid member 2 may be a metal foil such as an aluminum foil, a stretched film of polyethylene terephthalate, polypropylene, nylon or the like, various types of paper, or a laminate of these. In addition, an anchor coat agent layer may be provided in advance or a corona discharge treatment may be performed on the surface of the base material 3 on which the easily-sealable resin layer 4 is formed.

The easily openable resin layer 4 of the lid material of the present invention is composed of a mixture mainly composed of polyethylene terephthalate resin and polybutylene terephthalate resin. The polyethylene terephthalate-based resin forming the easy-open resin layer 4 is a copolymer of dicarboxylic acid as an acid component mainly containing terephthalic acid, and a mixture of ethylene glycol and 1,4-cyclohexanedimethanol as an alcohol component. Is. Terephthalic acid, which is the main component of dicarboxylic acid, is 80 to 100 mol% of the acid component, preferably 90 to 1
It occupies 00 mol%. Further, as the acid component other than terephthalic acid, 0 to 20 mol% of aromatic dicarboxylic acid and aliphatic dicarboxylic acid such as isophthalic acid, sebacic acid, adipic acid and azelaic acid can be used. The mixing ratio of ethylene glycol as an alcohol component and 1,4-cyclohexanedimethanol is preferably 40 to 80 mol% of ethylene glycol and 60 to 20 mol% of 1,4-cyclohexanedimethanol to the mixture. .. Ethylene glycol is less than 40 mol%,
When 1,4-cyclohexanedimethanol exceeds 60 mol%, the heat seal strength becomes small, and when ethylene glycol exceeds 80 mol% and 1,4-cyclohexanedimethanol is less than 20 wt%, the crystallization rate is high. This is not preferable because the low crystallinity impairs the heat fusion performance at a relatively low temperature. In addition, as the alcohol component other than the above mixture, diethylene glycol, butanediol, 1,6-hexanediol or the like is added in an amount of 0 to 20.
It can be used in the range of mol%. Such a polyethylene terephthalate resin has a good heat fusion property at a relatively low temperature, and when it is used for the easily-openable resin layer 4, the heat fusion temperature at the time of sealing the container 5 with the lid material 2 is lowered. be able to.

The polybutylene terephthalate-based resin constituting the easily-openable resin layer 4 is composed of dicarboxylic acid as an acid component having 50 to 90 mol% of terephthalic acid and 1,4-butanediol as an alcohol component. It is united. As acid components other than terephthalic acid, aromatic dicarboxylic acids such as isophthalic acid, sebacic acid, adipic acid, and azelaic acid and aliphatic dicarboxylic acids can be used in an amount of 10 to 50 mol%, preferably 15 to 40 mol%. Of these, isophthalic acid is preferable from the viewpoints of heat-sealing property and peeling property. Further, as alcohol components other than 1,4-butanediol, ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol,
A copolymer may be prepared by using 1,6-hexanediol, neopentyl glycol or the like in the range of 0 to 20 mol%.

By using such a polybutylene terephthalate-based resin together with the above-mentioned polyethylene terephthalate-based resin, not only the heat-sealing property at a relatively low temperature but also the easy-opening resin layer having a good unsealing property is obtained. It can be 4. For this purpose, the mixing ratio of the polyethylene terephthalate resin and the polybutylene terephthalate resin is 80 to 50 wt% of the polyethylene terephthalate resin and 20 to 50 wt% of the polybutylene terephthalate resin with respect to the resin mixture. preferable. Polyethylene terephthalate resin is less than 50 wt% and polybutylene terephthalate resin is 50 w
If it exceeds t%, the heat-sealing property at a relatively low temperature becomes poor, and the polyethylene terephthalate resin exceeds 80 wt%.
When the content of the polybutylene terephthalate resin is less than 20% by weight, the heat fusion property at a relatively low temperature is so good that the desired easy-open property cannot be obtained.

In the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a viscosity modifier, a lubricant, a pigment and the like may be added to the easily openable resin layer 4 if necessary. Further, inorganic fine particles such as titanium oxide and mica are 0 to 20 wt% with respect to the above resin mixture, preferably 0.01 to 1
You may add about 0 wt%.

In order to form the easily-openable resin layer 4 on the substrate 3, a method of melting the above-mentioned resin mixture and extruding and laminating on the substrate 3, or a film formed by using the above-mentioned resin mixture in advance is used. For example, a method of laminating the base material 3 with an adhesive may be used. Such an easily openable resin layer 4
The thickness of can be appropriately determined depending on the purpose of use,
Usually, it is about 20 to 150 μm.

The container 5 is formed of polyethylene terephthalate as a constituent material. The polyethylene terephthalate used in this container 5 is a polyester in which 80 mol% or more of the acid component is terephthalic acid and 80 mol% or more of the alcohol component is ethylene glycol. Other than polyethylene, ionomer, and polyethylene terephthalate described above. The polyester and the like are appropriately added. The deep drawing of the container 5 can be carried out by a known molding method such as injection molding, pressure molding, vacuum molding or the like.

To seal the container 5 by heat-sealing the lid member 2 as described above, a known method such as a heat sealing method or a high frequency induction heating method can be used. Next, the present invention will be described more specifically by showing experimental examples. Experimental Example An aluminum foil having a thickness of 50 μm was used as a substrate, an anchor coating agent (isocyanate compound) was applied to the aluminum foil, and the following resin mixture was applied onto the anchor coating agent by an extrusion laminating method to obtain a thickness of 30 μm. An openable resin layer was formed and then punched into a predetermined shape to obtain a lid material (Sample-1). (Composition of resin mixture) -Polyethylene terephthalate (PET) -based resin: 60 wt% Acid component: terephthalic acid: 100 mol% Alcohol component: Ethylene glycol: 50 wt% 1,4-Cyclohexanedimethanol: 50 wt% -Polybutylene terephthalate (PBT) ) Resin: 40 wt% Acid component: terephthalic acid: 80 mol% Isophthalic acid: 20 mol% Alcohol component: 1,4-butanediol: 90 mol% Ethylene glycol: 10 mol% Further, of the composition of the above resin mixture , Sample 2 and Comparative Samples 1 and 2 were prepared in the same manner as Sample 1 except that the mixing ratio of PET resin and PBT resin was as follows. -Sample-2: PET-based resin ... 75 wt% PBT-based resin ... 25 wt% -Comparative sample-1: PET-based resin ... 30 wt% PBT-based resin ... 70 wt% -Comparative sample-2: PET-based resin ... 90 wt% PBT-based resin 10 wt% Samples other than the composition of the resin mixture of Sample-1 except that the mixing ratio of ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM), which are alcohol components of PET-based resin, were as follows: Sample as in -1
3, Comparative Samples-3 and 4 were prepared. -Sample-3: EG ... 75 mol% CHDM ... 25 mol% -Comparative sample-3: EG ... 35 mol% CHDM ... 65 mol% -Comparative sample-4: EG ... 90 mol% CHDM ... 10 mol% A polyethylene terephthalate sheet having 90 mol% of terephthalic acid as a component, 10 mol% of isophthalic acid, 90 mol% of ethylene glycol and 10 mol% of 1,4-cyclohexanedimethanol as an alcohol component was prepared. Then, the above-mentioned respective lid material samples were heat-sealed to this film under the following conditions, and the sealing property, the unsealing property, and the high-speed heat-sealing suitability were evaluated by the following methods. (Heat fusion condition) Sealing temperature: 160 ° C to 220 ° C Sealing pressure: 2 kg / cm ² Sealing time: 1 second (Sealing property evaluation method) Peeling angle 18 by a tensile tester
The heat seal strength (kg / 15 mm) was measured at 0 ° and a pulling speed of 300 mm / min.

Evaluation Criteria 1.0 kg / 15 mm or more ... Good sealing property Less than 1.0 kg / 15 mm ... Poor sealing property (opening property evaluation method) Adhesive strength 1.0 kg / 15 mm-2.
When it was within the range of 2 kg / 15 mm, the unsealing property was good. (High-speed heat fusion suitability evaluation method) Adhesive strength 1.0 kg / 15
When the lowest temperature was lower than the melting peak temperature of the polyethylene terephthalate-based resin by 15 ° C. or more within the temperature range of mm or more, “◯” was given, and in other cases, “X” was given.

[0017]

[Table 1] The evaluation results are shown in Table 1. As is clear from Table 1, Samples -1 to 3 exhibited good characteristics. However, Comparative Samples-1 and 4 were inferior in sealing property and suitability for high-speed heat fusion, and Comparative Samples-2 and 3 were inferior in unsealing property.

[0018]

As described in detail above, according to the present invention, the easily-openable resin layer has a uniform thickness, the heat-sealing temperature to the container is low, the sealing speed can be increased, and the peeling can be achieved. It is possible to provide a lid material that is easy to open the container.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a package using an embodiment of a lid material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Packaging body 2 ... Lid material 3 ... Base material 4 ... Easy-opening resin layer 5 ... Container 6 ... Main body 7 ... Opening part 8 ... Flange part

Claims (1)

[Claims] 1. A container having an easily-openable resin layer on one surface of a base material and sealing the container by heat-sealing the easily-openable resin layer on the surface of the container formed of polyethylene terephthalate as a constituent material. In the lid material, the easily-openable resin layer comprises dicarboxylic acid as an acid component mainly composed of terephthalic acid, ethylene glycol 40 to 80 wt% as an alcohol component, and 60 to 20 wt% of 1,4-cyclohexanedimethanol. Polyethylene terephthalate resin that is a copolymer with a mixture 80 to 50 wt%, 50
It is formed by a resin mixture of 20 to 50 wt% of polybutylene terephthalate resin which is a polymer of dicarboxylic acid as an acid component having 90 to 90 mol% of terephthalic acid and 1,4-butanediol as an alcohol component. A lid material characterized by that.