JPH02171242A - Cover material for sealed packaging member - Google Patents

Abstract

PURPOSE:To raise the adhesiveness by forming an adhesive layer blended with a silane coupling agent to a polyurethane adhesive agent or a carboxyl group containing polyolefin resin on one side of a base material, and a specific thickness adhesive layer consisting of a carboxyl group containing polyolefin resin on the adhesive layer. CONSTITUTION:It may be a type having an adhesive layer blended with a silane coupling agent to a polyurethane adhesive agent or an adhesive layer blended with a silane coupling agent to a carboxyl group containing polyolefin resin, provided on one surface of a base material, and a connecting layer of 10 - 100mum in its thickness consisting of a carboxyl group containing polyolefin resin, provided on the adhesive layer. As a base material, it can preferably be used by aluminum foil and thin plate, plastic film, paper or laminate thereof. Inasmuch as the silane coupling agent is blended to the adhesive layer not coming into contact directly with the outside air, the silane coupling agent may not exhausted by reacting with moisture in the air, whereby a cover material can be improved in its storage stability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel material useful as a lid material for a sealed packaging container made of glass, ceramic, or the like. When the material of the present invention is used as a lid material, it exhibits excellent sealing performance over a long period of time not only for powder products but also for liquid products, and is easy to open and has a beautiful opening.

Prior art and its problems Conventionally, liquid or fluid contents such as alcoholic beverages, juices, dressings, mayonnaise, and jams are mainly stored in glass containers and sealed with metal or plastic screw caps. However, this has the disadvantage that it is very difficult to open and is expensive. Another method is to caulk an aluminum plate to the opening of the glass container and seal it, but this method is also difficult to open and is also expensive. Some glass containers for storing powders such as instant coffee and powdered cream are heat-sealed and sealed using a laminate material such as aluminum foil or paper that has been coated with a heat-sealing agent. When the container is used as a sealed package for a liquid or fluid, there is a drawback that the adhesive strength of the heat-sealed portion decreases significantly within a short period of time due to contact with the contents, resulting in peeling. Japanese Patent Publication No. 53-8278 discloses a technique of heat-sealing a silane compound to the open end surface of a glass container, but this method also has some problems. In other words, if the thickness of the sealant applied is not sufficient, it will be difficult to achieve uniform heat sealing due to irregularities in the opening of the glass container, variations in the parallel parts, etc.; if the thickness of the sealant is increased sufficiently, the cost will be significant. It gets expensive. In addition, after filling the contents into a glass container and sealing it, boil sterilization or retort sterilization is performed, but in this case as well, a combination of a glass container and a lid material that can sufficiently withstand high-temperature sterilization is required. The current situation is that it is difficult to obtain. Furthermore, paper, film, adhesive, etc. often remain at the opening of the container after opening, creating an unsightly appearance.

The present inventor has completed a sealed packaging material in which different thermoplastic resin layers are formed on the open end surface of a glass container and the lid base material, and has already applied for a patent (Japanese Patent Laid-Open No. 59-10386
No. 2 and JP-A-59-103863). A sealed package made of a combination of a glass container and a lid material has excellent heat-sealing properties, does not show a decrease in adhesive strength even when it comes into contact with liquid contents, is easy to open, and has a It has the excellent effect of making the container opening look beautiful. However, since it requires a step of forming a thermoplastic resin layer on the open end surface of the glass container, there is room for improvement from an economic standpoint.

Means for Solving the Problems In view of the problems of the prior art as described above, the present inventor has conducted various studies and found that these problems can be solved when using a specific composite material with a new configuration. It has been found that the problems are substantially eliminated or significantly reduced. That is, the present invention provides a lid material for a sealed package shown below: (a) a base material; (b) a silane coupling to a polyurethane adhesive provided on one side of the base material; or (c) an adhesive layer containing a carboxyl group-containing polyolefin resin and a silane coupling agent, and (c) a carboxyl group-containing polyolefin that has excellent adhesiveness with the adhesive layer provided on the adhesive layer. A lid material for a sealed package (hereinafter referred to as the first invention of the present application), characterized in that it has a bonding layer of 10 to 100 μm thick made of a resin based on the present invention;
and ■(a) Base material; (b) An adhesive layer provided on one side of the base material, which is a polyurethane adhesive mixed with a silane coupling agent, or a carboxyl group-containing polyolefin resin mixed with a silane coupling agent. Adhesive layer (c) made of a polyolefin resin with excellent adhesion to the adhesive layer provided on the adhesive layer and having a thickness of 10 to 100 μm
and (d) a bonding layer with a thickness of 10 to 100 μm made of a carboxyl group-containing polyolefin resin provided on the intermediate layer (hereinafter referred to as the present application). (Second invention)

The base material itself used in the first invention and the second invention of the present application is the same as that conventionally used as a base material for sealed packages, and includes aluminum foil and thin plate, plastic film, paper, or a laminate thereof. etc., so you can use
Although not detailed, specifically, aluminum foil and thin plate,
Examples include polyester film, paper, and laminates thereof.

The polyurethane adhesive that is the main component of the adhesive layer formed on one side of the base material in the first invention and the second invention of the present application basically consists of a combination of OH-based raw materials and NCO-based raw materials. There is. As an OH-based raw material, the molecule ff11000
Examples include the following low molecular polyols, polyether polyols, polyester polyols, and the like. NCO-based raw materials include tolylene diisocyanate (TDI), 4
．． 4-diphenylmethane diisocyanate (MDI),
NCO monomers such as hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone dicyanate (I PD I),
These are actually used after being modified into polyurethane prepolymers, trimer biuret, etc. Although there are various combinations of OH-based raw materials and NCO-based raw materials, the following are particularly recommended for food packaging materials.

(i) Polyester-urethane adhesive-A: Polyester urethane diol B: Polyisocyanate (adduct of IPDI/XDI/TMP) (11) Polyester-epoxy-urethane adhesive-A: Polyester urethane diol-B: Epoxy resin-C: Polyisocyanate = IPDI trimer No. 1 of this application
The adhesive layer of the present invention and the second invention of the present application provides sufficient adhesion between the base material and the bonding layer (the first invention of the present application) or between the base material and the intermediate layer (the second invention of the present application), and allows the sealed package to be sterilized by boiling. When subjected to heat sterilization such as retort sterilization, there is no deterioration in adhesiveness with glass containers or ceramic containers.
It is necessary to maintain good adhesion. For this purpose, 0.1 to 20 parts by weight of a silane coupling agent is used in combination with 100 parts by weight of the polyurethane adhesive. Examples of such silane coupling agents include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris-β-methoxyethoxysilane, and β-3,4-epoxycyclohexylethyltrimethoxysilane. , γ-lylolopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-aminoethoxy-γ -Aminopropyltrimethoxysilane and the like are exemplified. When the amount of silane coupling agent is less than 0.1 part by weight,
If the adhesive force to the container is not sufficient, and on the other hand exceeds 20 parts by weight, the adhesive force to the container will be reduced.

Examples of resins mainly composed of carboxyl group-containing polyolefin resins used in place of the above-mentioned polyurethane adhesives in the adhesive layers of the first invention and the second invention of the present application include ionomers, ethylene-acrylic acid copolymers, carboxyl group-containing polyolefin resins, etc. polyethylene, carboxylated polypropylene, carboxylated ethylene-vinyl acetate copolymer,
One or more of carboxylated saponified ethylene-vinyl acetate copolymers are used. Carboxylated polyethylene, carboxylated polypropylene, carboxylated ethylene-vinyl acetate copolymer, carboxylated saponified ethylene-vinyl acetate copolymer, etc. are polyethylene, polypropylene, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, etc. By copolymerizing an unsaturated carboxylic acid (maleic acid, fumaric acid, crotonic acid, acrylic acid, methacrylic acid, etc.) or its acid anhydride (maleic anhydride, itaconic anhydride, etc.) to a polyolefin resin, carboxyl groups can be created. This is the introduction of

The resin mainly composed of a carboxyl group-containing polyolefin resin may be a carboxyl group-containing polyolefin resin alone, and in order to further improve adhesiveness, polyethylene may be added to 100 parts by weight of the carboxyl group-containing polyolefin resin. , polyolefin resins such as polypropylene, vinyl resins, epoxy resins, acrylic resins, polyester resins, and styrene resins may be blended up to a maximum of about 100 parts by weight. The type, amount, etc. of the silane coupling agent used in combination with the resin mainly composed of carboxyl group-containing polyolefin resin are the same as in the above case.

The thickness of the adhesive layer of the first invention and the second invention of the present application is usually 10 μm or less, more preferably 4 to 8 μm.

By forming this adhesive layer, the adhesive force between the base material and the bonding layer (first invention of the present application) or intermediate layer (second invention of the present application) described below is improved, and when the sealed package is opened, the film etc. This prevents any residue from remaining in the opening of the container.

In the first invention of the present application, the carboxyl group-containing polyolefin resin formed as a bonding layer on the adhesive layer by means such as melt extrusion, thermocompression bonding of a film, and thermocompression bonding of a coextruded film is used as the main component of the adhesive layer. It may be the same as that.

This bonding layer needs to have good heat-sealing properties, cushioning properties, anti-corrosion properties, etc. for the container. Therefore, the thickness needs to be about 10 to 100 μm, and more preferably 20 to 50 μm. still,
In order to prevent blocking and improve slipperiness of the bonding layer,
A maximum of about 100 parts by weight of one or more of polyolefin resins such as polyethylene and polypropylene, vinyl resins, acrylic resins, polyester resins, and styrene resins per 100 parts by weight of carboxyl group-containing polyolefin resins. You can also add it.

In the second invention of the present application, an intermediate layer is provided at a position corresponding to the adhesive layer and the bonding layer of the first invention of the present application. This intermediate layer is made of a resin that has excellent adhesive strength between the adhesive layer and the bonding layer. As such resin, unmodified or modified polyolefin resin is used, and specifically, polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ionomer, polypropylene, silane-modified polyethylene, Examples include silane-modified polypropylene, carboxylated polyethylene, carboxylated polypropylene, carboxylated ethylene-vinyl acetate copolymer, and the like. These resins may be used alone or in combination of two or more.

This intermediate layer is for providing cushioning properties, corrosion resistance, etc., and therefore has a thickness of 10 to 100 μm.
degree, more preferably about 20 to 60 μm. Further, the intermediate layer may be a coextruded film layer of modified polyolefin and unmodified polyolefin.

In the lid material of the second invention of the present application, first, an adhesive layer is formed on the base material in the same manner as in the first invention of the present application, and then coating, hot melt extrusion, thermocompression bonding of a film, thermocompression bonding of a coextruded film, etc. After forming the intermediate layer by the method described above, by applying a solution or emulsion of the resin mixture to form the bonding layer onto the intermediate layer and drying it, or by hot-melt extrusion coating the resin mixture onto the base material. Manufactured.

Note that, if necessary, a printed layer, an overcoat layer, etc. can be provided on the surface of the lid material of the present invention opposite to the surface of the base material on which the bonding layer is provided, according to a conventional method.

The glass container used in combination with the lid of the present invention may be coated with a metal oxide film in the usual manner. That is, in the normal glass container manufacturing process, the glass container immediately after leaving the forming station, that is, the high temperature end (h
300-600℃ in a glass container
By spraying a solution of a metal compound such as tin tetrachloride at a certain level, an extremely thin film of a metal compound such as tin oxide is formed into the network structure of the glass, improving the mechanical strength and chemical stability of the glass container. Improving sexuality. According to the research of the present inventor, when the contents of the sealed package are liquid, the presence of such a thin film of metal oxide
It has been found that the water resistance of the adhesive portion between the glass container and the lid material is significantly improved. In addition, cleaning the glass container by immersing it in hot water or showering it with hot water can also improve the adhesiveness and water resistance of the bond between the glass container and the lid. It was found that it improved significantly.

When manufacturing a sealed package using the lidding material of the present invention,
In the same manner as in the conventional method, a container made of glass, ceramic, etc. is filled with the contents, a lid material is placed on the end face of the opening of the container, and then heat sealing is performed.

Heat sealing conditions may vary depending on the material, shape and dimensions of the container, the type of lid material, the contents to be filled, etc., but are usually performed at about 200° C. to 240° C. for about 1 to 2 seconds. As the heating means, known methods such as heating with a hot plate and high frequency induction heating are employed. The sealed package after heat sealing is subjected to high temperature sterilization treatment such as boiling sterilization, retort sterilization, etc., if necessary.

Effect of the invention According to the present invention, the following effects are achieved.

(1) Since the silane coupling agent is blended into the adhesive layer that does not come into direct contact with the outside air, the silane coupling agent may react with moisture in the air and be consumed during storage or handling of the lid material. This effectively eliminates the problem of Therefore, the storage stability of the lid material is significantly improved.

(2) It has become possible to directly heat-seal the container and the lid material without performing any pretreatment such as resin coating on the open end surface of the container made of glass, ceramic, etc.

(3) Since the seal formed between the container and the lid material has good water resistance, a sealed package containing a liquid or fluid substance maintains the quality of the contained substance stably over a long period of time.

(4) Since the seal portion has excellent heat resistance, the sealed package can be easily subjected to high temperature sterilization treatment such as boil sterilization and retort sterilization. Further, during the high temperature sterilization treatment, a portion of the silane coupling agent in the adhesive layer moves to the sealing portion, so that the sealed package exhibits good adhesive properties even after the treatment.

(5) Between the base material and the bonding layer (in the case of the first invention of the present application) and between the base material, the intermediate layer, and the bonding layer (in the case of the second invention of the present application)
Since the bonding force at
It is easy to open, and the container opening has a smooth and beautiful appearance.

EXAMPLES Examples and comparative examples are shown below to further clarify the characteristics of the present invention.

Example 1 γ-
2.5 parts of glycidoxypropyltrimethoxysilane was added to prepare an adhesive liquid.

- Apply the above adhesive liquid at a rate of 4 to 5 g/rf (as solid content) to the other side of a 50 μm thick aluminum foil with a 16 μm thick PET film bonded to the 14 μm thick PET film.
It was dried at 0-150°C for 15 seconds. Next, a bonding layer film having a thickness of 50 μm was bonded thereon using a hot roll. The bonding layer film used was a mixture of carboxylated high-density polyethylene and high-density polyethylene in a ratio of 85:15 and made into a film with a thickness of 50 μm by an inflation method.

On the other hand, after immersing a glass container whose opening end surface had been hot-end treated in hot water at 75°C for 5 minutes, hot water at 80°C was added, and the above-mentioned lid material (corresponding to the first invention of the present application) was used. Te, 2
Heat sealing was performed under the conditions of 10° C. x 4 kg/cJX for 2 seconds.

After the thus obtained sealed package was subjected to retort sterilization at 120° C. for 30 minutes, the sealed package was observed, and no abnormalities such as punctures were observed, nor was there any decrease in adhesive strength.

Furthermore, when the thus obtained sealed package was left in an inverted state at room temperature for 3 months, no water leakage due to a decrease in adhesive strength or deterioration in sealing performance occurred.

Furthermore, it was easy to peel off the lid and open the container, and no so-called "stiff mouth" due to residual adhesive layer on the lid was observed at the opening of the container.

In addition, as a storage stability test of the lid material, we tested the lid material at room temperature for 6 hours.
After being left in an atmosphere of 40° C. and 40° C. x 90% RH for one month, the same operation as above was performed using this, and it exhibited excellent performance in the same way as above.

Comparative Example 1 Except that no silane coupling agent was added to the adhesive layer,
When a lid material was manufactured in the same manner as in Example 1 and a glass container was sealed, a puncture occurred due to retort sterilization, and the lid material peeled off.

Example 2 A lid material of the second invention of the present application was obtained in the same manner as in Example 1 except that a 30 μm thick low-density polyethylene layer was provided as an intermediate layer between the adhesive layer of Example 1 and the bonding layer below. .

The bonding layer was formed by blending a carboxylated saponified ethylene-vinyl acetate copolymer and high-density polyethylene at a ratio of 85:15, and forming a film with a thickness of 30 μm by coextrusion and inflation of this mixed resin.

On the other hand, a glass container whose mouth opening end surface was subjected to hot end treatment was filled with hot water at 85°C, and using the above-mentioned lid material, 2
Heat sealing was performed under the conditions of 00°C x 4 kg/cl x 2 seconds.

When the thus obtained sealed package was left in an inverted state at room temperature for 6 months, no water leakage due to a decrease in adhesive strength or deterioration in sealing performance occurred.

In addition, the sealed package obtained in the same manner was held upside down at a temperature of 40°C.
℃ and 90% relative humidity for 3 months, water leakage due to decreased adhesive strength and deterioration of sealing properties.
had not occurred.

In addition, as a storage stability test of the lid material, we tested the lid material at room temperature for 6 hours.
After being left in an atmosphere of 40° C. and 40° C. x 90% RH for one month, the same operation as above was performed using this, and it exhibited excellent performance in the same way as above.

(that's all)

Claims (2)

[Claims] (1) (a) Base material, (b) An adhesive layer provided on one side of the base material, which is a polyurethane adhesive mixed with a silane coupling agent, or a carboxyl group-containing polyolefin resin with a silane coupling agent. and (c) a bonding layer with a thickness of 10 to 100 μm made of a carboxyl group-containing polyolefin resin with excellent adhesion to the bonding layer and (c) provided on the bonding layer. Lid material for sealed packages. (2) (a) Base material; (b) Adhesive layer made of a polyurethane adhesive mixed with a silane coupling agent, or a silane coupling agent mixed with a carboxyl group-containing polyolefin resin, provided on one side of the base material. Compounded adhesive layer (c) made of a polyolefin resin with excellent adhesion to the adhesive layer provided on the adhesive layer and having a thickness of 10 to 100 μm
A lid material for a sealed package, comprising: (d) a bonding layer having a thickness of 10 to 100 μm and made of a carboxyl group-containing polyolefin resin provided on the intermediate layer.