JP2836752B2 - Heat resistant lid material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a base material for packaging, particularly PTP packaging (Press Through).
Pack) Regarding the lid material for packaging, in particular, a specific colored or uncolored base material, that is, a metal foil such as an aluminum foil or a paper base such as thin paper such as glassine paper or white roll paper and a heat sealing layer. The present invention relates to a heat-resistant lid member provided with a resin composition layer.

(Prior art) The general form of PTP packaging is a processed plastic molded article in which a pocket is formed as a part of a container for storing contents, and an aluminum foil or glassine paper as a lid part thereof. It consists of two parts: a heat sealing layer on the base material and a lid material subjected to other processing.

As the plastic forming the container body, a vinyl chloride resin sheet has been used for a long time because of its excellent workability. In recent years, however, a polypropylene sheet has been used because of its excellent moisture resistance and its low cost. Is coming.

Aluminum foil occupies almost all uses as the base material of the lid material, but in some cases, paper base materials such as glassine paper are used for the purpose of specific effects or because they are inexpensive, Plastic sheets that have been processed to facilitate rupture have been proposed, but have yet to be practically used.

The lid material is usually printed with letters or designs on one or both sides of the base material, and further coated with a colorless or colored transparent heat-resistant coating on one side as necessary, or a heat-resistant plastic film By stacking
A heat-resistant resin layer is provided to protect letters and designs from being damaged during heat sealing, etc., and the other side is heat-pressed to a plastic container to be heat-sealed for colorless or colored heat sealing. It is manufactured by applying a coating agent and forming a heat sealing layer.

The filling and packaging operations of the contents in the packaging operation are performed by storing the contents to be packaged in the pocket portion of the container formed as a pocket by molding the concave portion of the plastic sheet such as the vinyl chloride resin or polypropylene, and then opening the container. The heat-sealing layer of the lid material made of aluminum foil or glassine paper or the like is laminated on the surface side so that the heat-sealing layer is in contact therewith. This is performed by applying heat and pressure to a non-pocket portion of the plastic container by heating and pressurizing with a hot-press device such as a heat-sealing bar or a heat-sealing drum.

The heating conditions vary depending on the type of the laminated material, but the heat sealing temperature is between 100 ° C. and 200 ° C., and the heat sealing pressure is 1-5 kg / cm ² , generally 1-3.5 kg / cm ^2. Often set to.

The heat sealing layer of the lid material is usually made of a thermoplastic resin,
Depending on the material of the plastic container, a resin composition mainly containing a resin having a high affinity for the material of the plastic container, such as a vinyl chloride (co) polymer, an ethylene-vinyl acetate copolymer, or a chlorinated polypropylene, is used. . In recent years, in order to facilitate identification of the contents of the package in the resin composition, a colorant such as a dye or a pigment is dispersed to color the heat sealing layer.

(Problems to be Solved by the Invention) However, in order to reduce the manufacturing cost, the speed of the filling and packaging process of the package contents has been increased, and thus the temperature and pressure at the time of heat sealing have been reduced. There is a tendency to be set higher than before. That is, the temperature at the time of heat sealing is 200 ° C. or more, and the pressure is more often performed in the range of 4 kg / cm ² or more, so that the heat sealing layer of the lid material is more easily flown, For example, the heat sealing temperature
Under the conditions of 220 ° C and a pressure of 5 kg / cm ² , the thickness of the conventional heat-sealing layer is partially different due to a local deviation of the heat-sealing pressure, and the heat of the lid material seen from the transparent container side is obtained. In the case of a colored heat sealing layer, the sealing layer surface causes uneven reflection due to light rays, and furthermore, the density unevenness referred to as color flow occurs, resulting in a phenomenon that the appearance is impaired. Adhesion failure occurs in portions where the resin flows significantly.

As a countermeasure, a method using a so-called silk seal, in which irregularities are provided on the pressure-bonded surface of a heat sealing bar or a heat sealing drum, and a regular fine grid like an engraved intaglio in gravure printing, for example, has been developed. Although the bias of the heat sealing strength tends to be slightly improved, the appearance defect due to the bias of the flow of the heat sealing layer, that is, the phenomenon of uneven reflection and color flow has not been solved.

Further, a method of suppressing the heat-resistant fluidity by increasing the softening temperature of the resin composition forming the heat sealing layer cannot be applied because the heat sealing strength is reduced.

(Means for Solving the Problem) The present inventor has developed a cover material for packaging, particularly PTP (Press Through P).
ack) As a result of repeated research to develop a lid material for packaging that does not cause uneven reflection or color flow phenomenon even when the temperature and pressure at the time of heat sealing in a plastic container are increased, aluminum foil is A resin mixture mainly composed of 60 to 90% of vinyl chloride-vinyl acetate copolymer (A) and 40 to 10% of thermosetting acrylic resin (B) , (A) + (B) =
100%. A) a coating agent in which a coloring agent is dispersed as necessary in an organic solvent solution, and drying to form a resin composition layer as an intermediate layer, and a heat sealing layer manufactured by providing a heat sealing layer thereon; When the lid material is heat-sealed in a plastic container, even if it is heat-sealed at a high temperature of 200 ° C or more, for example, a heat-sealing temperature of 220 ° C and a high pressure of 5 kg / cm ² , uneven reflection and color flow phenomenon may occur. The present inventors have found that there is no problem in the interlayer adhesion between the substrate and the heat sealing layer, and have reached the present invention.

The vinyl chloride-vinyl acetate copolymer, which is the first main component of the resin composition layer forming the heat sealing layer of the lid material and the intermediate layer of the base material, is not particularly limited, but is generally paint and adhesive. Suitable are those used in the field of chemicals, taking into account the physical properties, the production of the coating agent for forming the intermediate layer and the workability of coating, with a vinyl acetate content of 5 to 50% and a degree of polymerization of 300 to 1000. Are preferred. Further, in addition to vinyl chloride and vinyl acetate, for example, a polymerizable carboxylic acid such as (meth) acrylic acid or maleic acid having a carboxyl group, hydroxyethyl or hydroxypropyl (meth) acrylate having a hydroxyl group, or an epoxy group may be used as a monomer component. Copolymerized as a third monomer with a functional monomer such as glycidyl (meth) acrylate and an olefin such as ethylene or a copolymerizable monomer such as (meth) acrylate, or acetic acid in the copolymer Modified products such as those having a hydroxyl group introduced by hydrolysis of a vinyl group are also used as the main component.

The thermosetting acrylic resin, which is the second main component of the resin composition layer which is the intermediate layer between the base material of the lid material and the heat sealing layer of the present invention, has a hydroxyalkyl group, a glycidyl group, an aminoalkyl group and the like as pendant groups. Thermosetting for paints, such as a type using a crosslinking agent such as an amino resin, a polycarboxylic acid, a polyvalent ethyleneimine compound, a polyepoxide, or a polyisocyanate, or a so-called self-crosslinking type using a pendant alkyletherified methylol group. A commercially available acrylic resin is suitable.

The resin composition layer which is an intermediate layer between the base material and the heat sealing layer of the lid material of the present invention may contain additives or fillers usually used in paints, printing inks or adhesives.

A coloring agent is added to the resin composition layer as needed, and these are usually pigments or dyes used in paints and printing inks.

By configuring like the lid material of the present invention, it is not necessary to particularly consider uneven reflection and color flow phenomenon caused by the flow of the resin or the resin composition forming the heat sealing layer during the heat sealing. May be formed by applying a generally used heat sealant as described above. That is,
Since the material of the container of the PTP packaging is generally a vinyl chloride resin type or a polypropylene resin type, it is appropriate to use a resin composition containing a resin having a high affinity for each material as a main component. For example, a vinyl chloride (co) polymer is used for the former material, and a chlorinated polypropylene is used as a main component for the latter material, and ethylene-vinyl acetate copolymer and (meth) acrylate copolymer are used if necessary. Polymer, other resins such as rubber-based resin such as styrene-butadiene-based resin, rosin ester-based, terpene-based, phenol-based resin composition containing a so-called tackifier and the like with appropriate additives It can be formed by coating a coating agent dissolved in a solvent to form a solution.

Metal foil and paper are suitable as the base material of the cover material of the present invention. However, aluminum foil is used as the metal foil since easy bursting is required in consideration of durability, hygiene, price and use of PTP packaging. Among the papers, there are high quality paper, thin paper, glassine paper and the like, and glassine paper is particularly suitable.

The thickness of these substrates is 5 to 5 in the case of aluminum foil.
About 50μ is appropriate, and any of hard or soft can be used. In the case of paper, a paper having a thickness of 10 to 60μ is suitable, and in the case of glassine paper, a paper having a thickness of 20 to 40μ is suitable.

(Function and Effect) The resin composition layer forming the intermediate layer between the heat sealing layer and the substrate of the lid material of the present invention is a vinyl chloride-vinyl acetate copolymer (A)
And a thermosetting acrylic resin (B) as a main component, and the first main component, a vinyl chloride-vinyl acetate copolymer resin (A), is in the range of 60% to 90%, that is, the second main component. The thermosetting acrylic resin (B) as the main component must be in the range of 40 to 10% (however, (A) + (B) = 100%).

The proportion of the vinyl chloride-vinyl acetate copolymer resin (A) is 90
%, That is, the ratio of the thermosetting acrylic resin (B) is 10%.
%, The resin composition layer forming the intermediate layer easily flows together with the heat sealing layer during heat sealing, so that uneven reflection and color flow phenomenon are not improved.

When the proportion of the vinyl chloride-vinyl acetate copolymer resin (A) is lower than 60% and the proportion of the thermosetting acrylic resin (B) exceeds 40%, the resin composition layer forming the intermediate layer is Although no flow occurs during heat sealing, the adhesion of the heat sealing layer is reduced, and delamination easily occurs.

 Hereinafter, the embodiment will be described in detail.

(Example 1) Based on the formulation shown in Table 1, the whole amount of the vinyl chloride-vinyl acetate copolymer was added to and dispersed in toluene in a solvent while stirring, and the remaining methyl ethyl ketone in the solvent was added, followed by heating. After dissolution, a thermosetting acrylic resin was mixed to prepare a coating material for forming a resin composition layer, which is an intermediate layer between the heat sealing layer and the substrate of the lid material of the present invention, by coating.

In the resulting coating, fastgenbry as a pigment
After GNPT was added and mixed and moistened, the mixture was treated and dispersed at 1,700 rpm for 20 minutes using a batch type tabletop sand mill having a capacity of 500 cc to obtain a blue-colored coating agent for forming an intermediate layer.

The obtained blue coating was screened with a mesh density of 125 lines and a cell depth of 4
Using a 0μ engraved intaglio plate, apply the gravure printing method to the matte side on which the characters and designs of the semi-hard single-gloss aluminum foil with a thickness of 20μ are printed, heat dry, and further apply the following A heat sealable coating agent having the compounding composition was similarly applied by a gravure printing method so that the dry film thickness became 6 μm, and a heat sealable resin layer was provided to prepare a lid material for PTP.

(Heat sealable coating) 37 parts SWAREX CH40T (40% toluene solution of ethylene vinyl acetate copolymer manufactured by Taisei Chemical) 85 parts vinylite VMCH (vinyl chloride-vinyl acetate copolymer manufactured by UCC USA) Toluene 139 parts Methyl ethyl ketone 139 Part Total 400 parts The above-mentioned heat sealing layer of the PTP lid material is a hard vinyl chloride resin sheet with a thickness of 250μ (VS1202 manufactured by Sumitomo Bakelite Co., Ltd.)
Then, heat sealing was performed from the side of the aluminum foil using a heat sealing bar under the conditions of a heat sealing temperature of 160 ° C., a heat sealing pressure of 5.5 kg / cm ² and a pressurization time of 1 second, and the heat sealing strength was examined.

Next, the same sample was heat-sealed using a heat-sealing bar at a heat-sealing temperature of 260 ° C., a heat-sealing pressure of 4.0 kg / cm ² and a pressing time of 1 second, and the heat-sealed surface was observed. The presence or absence of the color flow phenomenon was examined.

The test results are shown in the performance evaluation column of Table 1. As a result, a sufficient value was obtained as the heat sealing strength, and no color flow phenomenon was observed.

(Example 2) As described in Table 1, in preparing the coating material for forming the intermediate layer in Example 1, the upper limit of the range of the present invention was taken as the ratio of the vinyl chloride-vinyl acetate copolymer, Therefore, the ratio of the thermosetting acrylic resin takes the lower limit value,
In the case where the pigment was not added to the coating material for forming the intermediate layer, the production of the coating material for forming the intermediate layer, the preparation of the lid material for PTP, and the performance evaluation were performed in the same manner as in Example 1.

The formulation of the coating agent for forming the intermediate layer and the evaluation of the performance as a lid material for PTP are shown in Table 1 in the same manner as in Example 1, but the heat sealing strength was good and no uneven reflection was observed.

Example 3 In Example 1, the lower limit of the range of the present invention was taken as the ratio of the vinyl chloride-vinyl acetate copolymer in the preparation of the vehicle for the coating agent for forming the intermediate layer. In this case, the ratio took the upper limit value, and the production of the coating agent for forming the intermediate layer, the preparation of the lid material for PTP, and the performance evaluation were performed in the same manner as in Example 1.

The formulation of the coating agent for forming the intermediate layer and the evaluation of the performance as a lid material for PTP are shown in Table 1 in the same manner as in Example 1. However, the heat sealing strength and the color flow phenomenon were all good.

(Comparative Example 1) In the preparation of a vehicle for a coating agent for forming an intermediate layer in Example 1, a value lower than the lower limit of the range of the present invention of the vinyl chloride-vinyl acetate copolymer was adopted, and therefore, the proportion of the thermosetting acrylic resin Was performed when the value exceeded the upper limit, and other conditions and operations were performed in the same manner as in Example 1.

The formulation of the coating agent for forming the intermediate layer and the performance evaluation as a lid material for PTP are shown in Table 1 in the same manner as in Example 1. No color flow phenomenon was observed, but the heat sealing layer and the intermediate layer were used. The adhesiveness between the resin composition layer and the resin composition layer was reduced, the heat sealing strength was significantly reduced, and a practically satisfactory value could not be obtained.

(Comparative Example 2) In the preparation of the vehicle for the coating agent for forming the intermediate layer in Example 1, the value of the ratio of the vinyl chloride-vinyl acetate copolymer exceeded the upper limit of the range of the present invention. When the ratio of the resin is lower than the lower limit, and when the pigment is not added to the coating material for forming the intermediate layer, the production of the coating material for forming the intermediate layer and PT
Preparation and performance evaluation of the lid material for P were performed in the same manner as in Example 1.

The results are shown in Table 1. Although the heat sealing strength was good, the resin composition layer as the intermediate layer was flowing together with the heat sealing layer in the heat sealing portion, and mottled reflection unevenness was generated. I was

(Example 4) In Example 1, instead of semi-rigid single-gloss aluminum foil, glassine paper having a basis weight of 30.5 g / m ² was used as a base material, and a coating agent for forming an intermediate layer was formed and a PTP layer cover material was used. The preparation and performance evaluation were performed in the same manner as in Example 1 with the same conditions and operations.

In the test for heat sealing strength, the glass showed sufficient strength to cause breakage in the glassine paper layer, and no color flow phenomenon was observed at all as in Example 1.

Claims (1)

(57) [Claims] 1. An intermediate layer between a substrate and a heat sealing layer, as an intermediate layer, a vinyl chloride-vinyl acetate copolymer (A) 60 to 90% (% by weight, the same applies hereinafter) and a thermosetting acrylic. A heat-resistant lid member provided with a resin composition layer containing a mixture of resin (B) 40 to 10% (where (A) + (B) = 100%) as a main component.