JPH0350704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lid material for an easy-to-open sealed package.
Generally, when packaging liquid contents in containers,
The container is filled with the contents, and then the lid and container are heat-sealed and sealed. In this case, since it is impossible to completely eliminate liquid dripping from the filling nozzle and the like when filling the contents, there is a high possibility that the liquid will adhere to the flange, which is the part of the container that is heat-sealed. Therefore, a sealant with good foreign substance sealing properties is desired. Furthermore, with current heat sealers, the temperature of the mold for heat sealing varies widely, so a sealant with a wide heat sealing temperature range for easy opening is desired. In other words, the optimal sealant for the lid material is one that has a wide heat-sealing temperature range for easy opening and has good heat-sealability against contaminants.

However, there are currently few lidding materials for polyester containers that provide easy-opening properties, and there is only one that coats the base material with a heat-sealing agent.
This has poor contaminant sealing properties and is not suitable for packaging products with a high solid content such as youth.

For these reasons, there is a demand for a lid material that has good heat-sealing properties against contaminants and has a wide heat-sealing temperature range for easy opening.

The present inventor aimed to develop a lid material for sealing polyester containers, which has good contaminant heat-sealability, can be heat-sealed with a strength that makes it easy to open, and has a wide heat-sealing temperature range. As a result of research, saturated polyester resin 20~80
% by weight and a blend of 20 to 80% by weight of a polyethylene resin, it is possible to form a sealing layer that has good contaminant heat-sealability to a polyester resin container and can be heat-sealed with a strength that makes it easy to open. and that it is possible to form a flat and thin film by co-extruding the blend with other resins, and that the lid material has a sealing layer made of the co-extruded blend and a support layer supporting it laminated on a base material. It has been discovered that the peeling strength is almost independent of the heat-sealing strength and that the appearance of the peeled surface after opening is good because the unsealing is performed by collective destruction of the sealing layer and delamination between the sealing layer and the support layer, and this knowledge has been achieved. The present invention has been completed based on this.

That is, the gist of the present invention is to provide a support layer formed by extrusion of one or more layers on a base material, and the support layer made of a blend of 20 to 80% by weight of a saturated polyester resin and 20 to 80% by weight of a polyethylene resin. This lid material is characterized in that a sealing layer extruded together with the lid material is laminated thereon.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

The first time shows the lid material 4 of the present invention.

Support layer 1 consisting of one layer or multiple layers extruded on base material 3 and saturated polyester resin
20-80% by weight and polyethylene resin 20-80% by weight
An extruded sealing layer 2 is laminated together with the support layer made of a blend of.

The lid material of the present invention described above can be effectively utilized for sealing containers made of polyester resin.

The sealing layer of the lid material of the present invention, which is made of a blend of saturated polyester resin and polyethylene resin, exhibits good heat-sealability for containers made of polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polybutylene terephthalate. Further, the sealing layer of the lidding material of the present invention exhibits cohesive failure properties, and its adhesive interface is completely fused to the flange surface, so there is no fear of bag breakage and the sealing property against foreign substances is excellent.

Figures 2 a to c show the process of unsealing the lid material of the present invention heat-sealed to the polyester resin container body, Figure 3 a shows the state before opening, Figure 3 b shows the state in the middle of opening, and Figure 3c shows the state after opening.

Immediately after opening, cohesive failure of the seal layer 2 occurs from point A between the flange 6 of the container body 5 and the seal layer 2 to point B between the seal layer 2 and the support layer 1, and then the seal layer 2 and the support layer Peeling occurs along the interlayer of layer 1, and then cohesive failure of sealing layer 2 occurs from point C between sealing layer 2 and support layer 1 to point D between flange 6 and sealing layer 2. As a result, it can be opened.

As described above, since the lid material of the present invention can be opened by cohesive failure of the sealing layer and peeling between the sealing layer and the support layer, the appearance of the container flange surface after opening is beautiful.

Further, since the unsealing is performed by cohesive failure of the sealing layer and peeling between the sealing layer and the support layer, the peeling strength at the time of unsealing hardly depends on the heat-sealing strength.

In packaging containers for foods, etc., they do not peel easily during processing and distribution processes after sealing, but they maintain easy-open properties. Heat sealing has a peel strength of 1200 to 1800 g / 15 m / 1200 to 1800 g / 15 m / It is known that it is given in a range of m width. On the other hand, although the heat sealing temperature varies depending on the performance of the sealer and the actual packaging conditions, it is unavoidable that the heat sealing temperature will range from 30 to 40°C. Therefore, it is required that the fusion strength be maintained within the above-mentioned preferred range over as wide a sealing temperature range as possible. The lid material of the present invention satisfies this requirement.

In the present invention, the saturated polyester resin that is the constituent material of the blend forming the sealing layer includes phthalic acid, isophthalic acid, terephthalic acid, maleic acid, maleic acid derivatives, succinic acid,
Saturated polybasic acids such as adipic acid and sebastic acid and ethylene glycol, diethylene glycol, glycerin, trimethylolpropane, 1,2 propylene glycol, 1,3 butanediol, dipropylene glycol, 1,4 butanediol,
1,6 hexanediol, pentaerythritol,
It is a saturated polyester resin obtained by ester bonding with polyhydric alcohols such as sorbitol, glycerin, neopentyl glycol, and 1,4 cyclohexanedimethanol.

This saturated polyester resin is desirably one that melts at 100 to 150°C in order to be blended with the polyethylene resin. For example, the acid comonomer is phthalic acid, and the alcohol comonomer is ethylene glycol and 1,4-cyclohexanedimethanol. Softening point 80℃, molecular weight 25000, density
1.26 saturated polyester resin is preferred. or,
Molding at around 200°C provides the best compatibility and moldability.

On the other hand, the polyethylene resin to be blended with the saturated polyester resin includes high density polyethylene, medium density polyethylene, low density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ionomer, ethylene-ethyl acrylate. It is a polyethylene resin containing an ethylene content of 50% by weight or more, which is an ethylene copolymer such as a copolymer or a saponified ethylene-vinyl acetate copolymer.

Next, in the present invention, the blend ratio of the saturated polyester resin and the polyethylene resin is preferably 20 to 80% by weight of the polyethylene resin to 20 to 80% by weight of the saturated polyester resin, as described above. If the content of the saturated polyester resin is less than 20% by weight, the strength of the heat seal with the polyester resin container will be weak, whereas if the content of the saturated polyester resin is more than 80% by weight, the seal layer will not undergo cohesive failure and will not completely melt. It does not show easy opening. Further, a suitable thickness of the sealing layer is 1 to 50 .mu.m, with 5 to 20 .mu.m being most suitable. If the seal layer is less than 1μ, the contaminant sealing property will be poor and the seal strength will be unstable, which is undesirable.On the other hand, if the seal layer is more than 50μ, after opening,
A large amount of the blend that makes up the sealing layer remains on the flange, resulting in a poor appearance of the flange, and in extreme cases, the sealing layer remains on the container side, causing a phenomenon called film sticking, making it impossible to remove the contents.

Next, in the present invention, the support layer must be laminated to the sealing layer with appropriate adhesive strength,
Therefore, suitable resins for the support layer include high-density polyethylene, medium-density polyethylene, low-density polyethylene, ethylene-α-olefin copolymer, and ethylene-vinyl acetate copolymer.

The thickness of the support layer is preferably 10μ or more, and 10μ
If it is less than that, the support layer will break when the package is opened, and a film bulging phenomenon will occur as shown in the fourth figure.

Next, in the present invention, heat-resistant plastic film, metal foil, paper, etc. can be used as the base material. The base material is polyethylene terephthalate,
Stretched nylon and aluminum foil are most suitable, and polyethylene, polycarbonate, polystyrene, and polyvinyl chloride are also suitable.

The thickness of the base material needs to be at least 12μ so that when used as a base material, it has appropriate rigidity when opened.

Further, the optimum thickness of the base material is 20 to 50μ.

Next, in the present invention, the method of providing the support layer and the sealing layer on the base material is to co-extrude the resin for the support layer and the resin for the sealing layer to form a laminated film, and then dry-laminate the laminated film on the base material. Alternatively, the resin for the supporting layer and the resin for the sealing layer may be co-extruded directly onto the base material.

As already mentioned, the lidding material of the present invention is ideal for use as a lidding material for heat-sealing polyester injection molded, blow molded, or sheet molded containers, and can also be molded into a flat film shape to form a drop lid. can be used arbitrarily.

From this point of view, the lid material of the present invention can be used for soft drinks,
Can be used for containers for carbonated drinks, seasonings such as soybean oil, detergents, etc.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 A 40μ thick aluminum foil was used as the base material, an anchor material was applied to its surface, and 10μ of the following 1:1 blend of saturated polyester resin and polyethylene was coextruded with 20μ of the following polyethylene. A lid material was prepared.

(1) Saturated polyester resin Acid comonomer is phthalic acid Alcohol comonomer is ethylene glycol and 1.4-cyclohexanedimethanol Softening point: 80℃, molecular weight: 25000, density: 1.26 (2) Polyethylene density: 0.923, MT=3.7 This lid material has a thickness of m/m polyethylene terephthalate injection plate (Toyobo RT-543) and temperature: 180℃, pressure: 20Kg/
Heat-sealing was performed under heat-sealing conditions of cm ² and time: 1 second.

After being left to cool, a peel test was performed and it showed good easy opening properties.

Example 2 The blended resin used in Example 1 and polyethylene were coextruded by the inflation method,
A laminated film having a layered structure of 10μ of blend resin/20μ of polyethylene was formed.

Next, a lid material was formed by bonding the polyethylene side of this laminated film to the aluminum side of a base material (polyester 12μ/AI40μ) using an isocyanate adhesive.

When we conducted a peel test on this lid material, we found that
It showed good easy openability.

As detailed above, the lid material of the present invention not only allows polyester resin containers to be opened and sealed easily, but also has good heat-sealing properties against foreign substances, and has a heat-sealing temperature range for easy-opening heat-sealing. It has the advantage that it can be peeled off and opened cleanly without damaging the flange surface of the container after opening.

[Brief explanation of drawings]

Figure 1 is a sectional view of the lid material of the present invention, Figures 2 a to c
FIG. 3 is a cross-sectional view showing the process of opening the lid, and FIG. 3 is a cross-sectional view showing the film bulging phenomenon that occurs when the support layer is torn. DESCRIPTION OF SYMBOLS 1... Support layer, 2... Seal layer, 3... Base material, 4... Lid material.

Claims (1)

[Claims] 1 Extruded support layer consisting of one or more layers on the base material and saturated polyester resin20
A lid material for a polyester container, characterized in that a sealing layer extruded together with the support layer made of a blend of ~80% by weight and a polyethylene resin and 20~80% by weight is laminated thereon.