JPH09164626A - Barrier laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminate having both of high barrier properties and excellent environmental adaptability by preliminarily laminating a biodegradable plastic to the surface of a paper base material before vapor deposition. SOLUTION: In a laminate wherein a vapor deposition layer of a metal or a metal oxide is provided on a paper base material, a biodegradable plastic is preliminarily laminated to the surface of the paper base material before vapor deposition. The vapor deposition surface of the paper base material is smooth coated paper and, as the coated paper, clay coated paper is used. A resin film with a thickness of 1-10μm is provided on the clay coated paper. As the biodegradable plastic, an aliphatic polyester can be used and, as the aliphatic polyester, other than a resin based on lactic acid, an aliphatic polyester produced by organisms having a hydroxyalkanol ether unit and an aliphatic polyester by chemical synthesis can be used. The coating thickness of the biodegradable plastic is 1-200μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminate. More specifically, it relates to a barrier laminate used as a material for a packaging material such as a container mainly made of paper used for transportation, storage or preservation of foods, chemicals, industrial products and the like.

[0002]

2. Description of the Related Art In general, for transporting, storing and preserving foods, chemicals and industrial products, there are some containers and materials for which barrier function (oxygen resistance, steam resistance) is required for the purpose of protecting contents. Especially for those intended for long-term storage of food, a particularly high barrier property is required. This barrier property prevents changes in capacity or concentration due to volatilization and evaporation of the contents, and prevents oxidative deterioration due to oxygen from the outside. The degree of barrier property required for paper containers for transportation, storage and preservation varies depending on the content and the method of use, but in general, polyvinylidene chloride (PVDC) is required to obtain high barrier property in these structures. )
Etc. Synthetic polymer is coated on the paper for several μm to several tens of μm, and the water vapor barrier property (10 g / m ²
・ 24 hours or less) ・ Oxygen barrier property (10 cc / m ²・
24 hours or less), a method of laminating polyethylene, polypropylene or the like by a melt extrusion method in an amount of 10 μm to 50 μm to give only a water vapor barrier property (10 to 50 g / m ² · 24 hours or less), or a biaxially stretched polyester film or A method of attaching a biaxially oriented polypropylene film with an adhesive is also used (see Table 1).

[0003]

[Table 1]

However, in the case where the laminate obtained by these methods is used for landfill treatment or becomes scattered dust in the natural world after use, the natural constituent paper which is the main constituent of the laminate is a single substance. Quickly absorbs water, swells and falls apart, and is decomposed by microorganisms,
~ A film with polyethylene film of several tens of µ laminated is not only left in its original form as a coating or film and left in the natural environment for a very long time, but also laminated with paper used as a laminate. Because of being
Disassembly will be slower than when using paper alone, and the original degradability function will be significantly impaired. Further, when the PVDC coating has a chlorine compound in the case of PVDC constitution for imparting barrier properties, it is feared that dioxin will be generated during combustion in the incineration process, and there is a tendency to refrain from using it in the field of packaging materials. .

On the other hand, the excellent environmental compatibility (decomposability and easy incineration) of paper has been reviewed, and conversion from plastic to paper base material has been proposed and replaced in various fields and applications. At the same time, in recent years, biodegradable resins that have begun to be supplied to the market are being commercialized with environmental compatibility as a selling point. We have already proposed the combination of paper and biodegradable plastic. The contents are a laminated body using a biodegradable plastic as a plastic to be laminated on a paper in a paper container mainly made of paper, and a method for producing the same (JP-A-6-6294).
No. 4). Furthermore, by using a biodegradable plastic with thermoplasticity, we proposed a paper container characterized by the fact that the entire container has biodegradability, making full use of its suitability for box making as a container material utilizing its heat sealing performance. (JP-A-6-64111).

When the above-mentioned materials are used for the purpose of protecting the contents for transportation, storage and preservation of foods, chemicals, industrial products, etc., biodegradable plastics are mostly aliphatic polyesters and therefore have a chemical structure. In addition, since it has a good affinity with water molecules, it has no water vapor barrier property and almost no oxygen barrier property, so that it is functionally insufficient in terms of protecting the contents. The gas permeability of currently available biodegradable plastics is such that the water vapor permeability per 30 μm film is 1
000 to 100 g / m ² · 24 hr, oxygen permeability is 1000 to 4000 per 30 μm film excluding biodegradable plastic containing polyvinyl alcohol as a main component.
cc / m ² · 24 hr, both values have a water vapor permeability of about 10 g / m ² · 24 hr or less, and an oxygen permeability of 50 cc / m ² · 24 hr or less, which are required for barrier properties. It is impossible to produce a laminate having a barrier function as a whole by simply laminating it with paper.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a heat-sealable laminate mainly composed of paper used as a material for a paper container, etc. Prevents chemical reactions such as oxidative deterioration of the contents of the product, and is excellent in environmental compatibility and high barrier property even when it is incinerated / landfilled after use, or when it becomes scattered dust in nature. The object is to provide a laminate having both environmental compatibility.

[0008]

The present invention has been conceived in order to solve the above-mentioned problems, and the invention of claim 1 is a laminate in which a vapor deposition layer of a metal or a metal oxide is provided on a paper base material, A biodegradable plastic is laminated on the surface of a paper substrate in advance before vapor deposition, and a barrier laminate having the invention of claim 2 is provided with a vapor deposition layer of metal or metal oxide on the paper substrate. In the laminated body, a barrier laminated body characterized in that the paper base material is a coated paper having a smooth vapor-deposited surface, and the invention of claim 3 further comprises a biodegradable plastic on the vapor-deposited layer of metal or metal oxide. 3. The barrier laminate according to claim 2, wherein the biodegradable plastic has a coating thickness of 1 to 200 μm.
5. The barrier laminate according to claim 1 or 3, characterized in that m is used, and the invention according to claim 5 uses clay-coated paper as the coated paper. The invention according to claim 6 is the barrier laminate according to any one of claims 2 to 5, wherein the clay-coated paper is provided with a resin coating having a thickness of 1 to 10 µm. The degradable plastic is a resin containing lactic acid as a main component.
The barrier laminate according to any one of 1 to 6 above.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
A vacuum deposition method, a sputtering method, an ion plating method, a reactive vacuum deposition method or a reactive sputtering method for forming a film of a metal or a metal oxide layer in a reactive gas atmosphere such as oxygen gas, and such PVD. Besides, it is already known to provide a vapor-deposited layer by a plasma activated CVD method to impart a desired barrier property to a substrate such as a film or paper.

As a method of imparting this barrier function to the paper itself, we have already provided a very thin coating as a sealing layer on the surface of the paper base material, and then used metal or metal oxide or metal and metal oxide. Inventing a packaging material having an excellent barrier property and a packaging container using the same, which is characterized by forming a vapor-deposited layer made of PTP, which is now widely used in pharmaceutical packaging materials as an environment-friendly product. We have proposed a structure that does not use aluminum foil, which is especially disliked by incineration, instead of the aluminum foil used for packaging (Japanese Patent Application No. Hei 6).
-50361). It is necessary that the paper that is the base material of the barrier paper is clay-coated paper having excellent smoothness on the surface or clay-coated paper having particularly improved smoothness. Here, the smoothness of the clay-coated paper is a factor that greatly affects the development of barrier properties. As a type of clay-coated paper, clay-treated pure white roll paper using a Yankee dryer in the drying process at the time of papermaking, and further supercalendering, what is said to be specially processed paper with particularly excellent smoothness, It is one of the most effective base materials that have barrier properties, and this specially-processed paper is coated with a resin on the clay-coated surface as a deposition-stopping layer for vapor deposition to provide smoothness and sealing properties. It proposes to effectively impart a barrier property.

In the above method, when a resin coating is provided on the surface of a paper base material and then vapor deposition is performed, by appropriately selecting and using the resin coating provided on the paper base material and the surface, cracks are caused by a vapor deposition layer to be overlaid thereon. It is possible to obtain excellent barrier properties with few defects, etc., and it can be incinerated as paper, providing a material compatible with the environment. However, when it is landfilled after use, or when it becomes scattered dust in the natural world, a film of 10 μm remains in the natural state as it is, so the original biodegradability of paper is sufficient. It wasn't working out.

As a result of intensive studies on the above problems, the present invention uses a barrier material, such as barrier function and environmental compatibility, when a barrier paper base material and a thermoplastic biodegradable plastic are combined. It is shown that the function that is contradictory from the material surface can be obtained by specifying the coating conditions, especially the thickness of the resin coating. Furthermore, the biodegradable plastic layered on top of the vapor-deposited layer not only imparts box-making suitability, etc., but when used after landfill treatment or when it is released into the natural world, not only the paper, but also the resin film for smoothing is quickly available. It also has the function of breaking apart. Here, although it is environmentally compatible due to “breaking apart” decomposition, unlike the overall meaning of “biodegradability” in which all substances used are biodegradable, smoothing Therefore, even if a resin that does not have biodegradability is used because the resin film is extremely thin, if it scatters in the natural world, the resin layer of several μm will not biodegrade, but the film is thin, so the shape is maintained. It can be considered that it can contribute to environmental conservation in the form of "disintegration", which means that the forms cannot be disintegrated into pieces.

The main point of the present invention is to what extent the thickness of the resin film for smoothing can achieve both the barrier function and the environmental compatibility (disintegration function). Excellent barrier performance depends on whether or not the vapor-deposited layer is formed as a complete film. For that purpose, it is sufficient to seal the underlying clay-coated paper with resin and smooth it further. It is necessary to find out.

As the smoothing resin that can be used here, a resin using a general chemically synthesized coating resin can also be used. The resin at this time is acrylic polyol resin, polyester resin, polyester /
Melamine resin, nitrified cotton / acrylic polyol resin, nitrified cotton resin, amino / alkyd resin, etc. can be used. As a coating method, a general method may be used, and a method of coating with a solvent dispersion or emulsion system is preferably used. At least the smooth-treated surface of the clay-coated paper coated with the sealing resin is made of metal or general formula A _X.
A thin film layer of metal oxide having a composition of O _Y (A is a metal and X and Y are positive real numbers) having a thickness of 100 to 3000 Å is deposited. As the vapor deposition method, a vacuum vapor deposition method, a sputtering method, an ion plating method, a reactive vacuum vapor deposition method or a reactive sputtering method in which a film is formed in a reactive gas atmosphere such as oxygen gas, or plasma in addition to such PVDC. The activation CVD method can be used. Further, a glass coating formed by applying a water-soluble polymer, an aqueous solution containing at least one of a metal alkoxide and a hydrolyzate thereof, or tin chloride, or a coating agent containing a water / alcohol mixed solution as a main component as a sealing layer. It is possible to effectively obtain the barrier property by providing the above structure and providing the vapor deposition layer on the above structure.

The biodegradable plastic having thermoplasticity is further laminated on both surfaces of the material vapor-deposited on the paper prepared as described above, or at least on the vapor deposition surface. Aliphatic polyester can be used as the biodegradable plastic. As the aliphatic polyester, in addition to a resin containing lactic acid as a main component, a biologically produced aliphatic polyester having a hydroxyalkanoate unit and an aliphatic polyester obtained by chemical synthesis can be used.

As the resin mainly containing lactic acid, lactic acid having a number average molecular weight of 10,000 to 100,000 is preferable,
It may be a copolymer of lactic acid and oxycarboxylic acid, and the lactic acid may be D-lactic acid, L-lactic acid or a mixture thereof. Further, glycolic acid or 6-hydroxycaproic acid can be used as the oxycarboxylic acid. In addition, as a microorganism-produced aliphatic polyester having a hydroxyalkanoate unit, 3-
Hydroxyvalerate, 3-hydroxybutyrate, 3
-Hydroxycaproate, 3-hydroxyheptanoate and P (3 having various functional groups in their side chains
It is possible to use one or a mixture of two or more HA) copolymers. The number average molecular weight of the aliphatic polyester obtained by chemical synthesis is 10,000 to 10,000.
The resin represented by (Chemical formula 1) of 0, the resin represented by (Chemical formula 2) having a number average molecular weight of 25,000 to 70,000, or a mixture of these resins may be used.

[0017]

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[0018]

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The method of laminating the biodegradable plastic may be a method used in the production of ordinary plastic laminated paper, such as lamination of the paper and the biodegradable plastic film, melt extrusion coating of the biodegradable plastic on the paper, and the like. Can be laminated by the method of. Then, the biodegradable plastic may be laminated on one side or both sides of the paper according to the application by the above method. Furthermore, when laminated on both sides, the types of biodegradable plastics used on both sides may be different.

[0020]

The present invention will be described below with reference to examples. <Example 1> As the coated paper, a special coated paper "Ryuo coated paper" (73 g / m ² ) (manufactured by Daio Paper Co., Ltd.) was used.
A polyester / melamine resin was applied as a sealing layer on the coated surface by a gravure coating method so that the coating amount was 10 g / m ² , 7
g / m ² , 5 g / m ² , 2 g / m ² coating, respectively, film thickness 7 to 10 μm, 5 to 7 μm, 3 to
A 5 μm or 1 to 3 μm smoothed coated paper is prepared, and a vacuum evaporation method is used to provide a vapor deposition layer of about 1000 liters of silicon oxide to form a barrier substrate.
Aliphatic polyester "Bionole # 1910" (Showa Highpolymer Co., Ltd.) at a processing temperature of 240 ° C in a die-type melt extruder
Manufactured) to a thickness of 20 μm to obtain a barrier laminate. For comparison, see “Ryuo Coated Paper” (7
3g / m ² ) polyethylene by extrusion coating method,
Mirason 14P (manufactured by Mitsui Nisseki Polymer Co., Ltd.) is coated at a processing temperature of 320 ° C. to a thickness of 15 μm and 10 μm, and the surface thereof is vacuum-deposited to about 1,000.
Å A silicon oxide vapor deposition layer is provided to create a barrier substrate,
Similarly to the above, "Bionole # 1910" was coated to a thickness of 20μ, and a polyester film, 12μE5100 (Toyobo) was also provided with a silicon oxide vapor-deposited layer of about 1000Å, and "Bionole # 1910" was added. Was coated to a thickness of 20 μm to prepare a laminate. The water vapor permeability and the oxygen permeability of the laminated body were measured and found to be 5 g / m ² · 24, respectively.
5 hr / hr or less, 5 cc / m ² · 24 hr or less, is 5 g / m
² · 24hr or less, 5cc / m ² · 24hr or less, and 5g / m ² · 24hr or less, 30cc / m ² · 24h
r is 50 g / m ² · 24 hr, 50 cc / m ² · 2
4 hr, 30 g / m ² · 24 hr, 1000 cc /
m ² · 24 hr, is 40 g / m ² · 24 hr, 100
0 cc / m ² · 24 hr and 5 g / m ² · 24 h
r was 5 cc / m ² · 24 hr or less.

This laminate was embedded in a field soil at a depth of 10 cm, and the state of decomposition was observed. As a result, it was found that a vapor deposition layer was formed on a melamine coat of 1 to 2 μm.
After about a month, holes began to appear on the biodegradable plastic surface. 3
After a month, the paper, including the paper, became disassembled sooner than the comparative product that was vapor-deposited on the paper and became uncollectible. The film having a coating thickness of 3 to 5 μm remained in shape for 3 months, but the biodegradable plastic surface was similarly decomposed.
After 5 months, it fell apart as well. Coating thickness 5-7
When the value of μm was confirmed after 5 months, the degradable plastic had completely disappeared, but the resin coated on the paper surface maintained its shape so as to prevent the paper from collapsing. This did not change after 7 months. When the thickness was 7 to 10 μm, it remained so as to prevent the collapse of the paper even more significantly after 7 months. When this was confirmed one year later, it could be confirmed that the paper coated with the resin layer on one side remained without being broken up. Similar to the state of using polyethylene or polyester, even if one year has passed, even if the biodegradable plastic part is decomposed, the paper part has non-degradable plastic adhered to one side. However, it was confirmed that they remained without breaking apart at all. The above results are shown in Table 2.

[0022]

[Table 2]

<Example 2> As a biodegradable plastic, a copolymer resin of lactic acid and oxycarboxylic acid (TYB-250 manufactured by Toyobo Co., Ltd.) was used, and toluene / MEK (50%) was prepared so that the solid content was 20%. : 50) It was dissolved in a solvent. Ryuo coated paper (73 g / m ² ) which is a special coated paper is used as the paper base material, and the coating material is applied to the coated surface,
(1) No. 5 bar with 20 bar coater, (2) N
o. It was coated to a thickness of 12 μm with a 36 bar coater, and the paper base material was subjected to smoothing treatment and sealing treatment. Next, a barrier substrate was prepared by providing a vacuum-deposited silicon oxide vapor deposition layer of about 1000 liters on the surface coated with this biodegradable plastic. Furthermore, paper base material, Ryuo coated paper (7
3 g / m ² ) coated surface of the aliphatic polyester “Bionole # 19 at a processing temperature of 240 ° C. by a T-die type melt extruder.
10 "(manufactured by Showa Highpolymer Co., Ltd.) to a thickness of 30 μm and 100 μm, and a vapor-deposited layer of about 1000 liters of silicon oxide is provided on the surface coated in the same manner as above to form a barrier substrate. Created. When the water vapor permeability and the oxygen permeability of the laminated body were measured, it was 50 g.
/ M ² · 24hr, 50cc / m ² · 24hr, is 1
0 g / m ² · 24 hr, 30 cc / m ² · 24 hr,
Is 5 g / m ² · 24 hr, 5 cc / m ² · 24 hr,
Was 1 g / m ² · 24 hours or less and 1 cc / m ² · 24 hr or less. Depth of all these laminates in field soil 10c
It was buried at m and the state of disassembly was observed.
After about a month, holes began to appear on the biodegradable plastic surface. 3
After a month, the paper, including the paper base, fell apart and became unrecoverable. After one year, everything was disintegrated and it was difficult to confirm. <Comparative Example 2> The same paper substrate as in Example 2 was directly coated with a vapor deposition layer of about 1000 liters of silicon oxide by a vacuum vapor deposition method, and a polyester / melamine resin was applied as a sealing layer to a thickness of 10 μm. As a comparative example, a silicon oxide vapor-deposited layer having a thickness of about 1000Å was provided. Water vapor permeability and oxygen permeability are over 10,000g / m ² · 24hr,
10000cc / m ² · 24hr or more, 5g / m ²
・ 24 hours or more, 5 cc / m ² · 24 hours or more. When these laminates were buried in a field soil at a depth of 10 cm, and the state of decomposition was observed, there was almost no change in either of them in the first month, and after three months vapor deposition treatment on paper became disjointed and unrecoverable. However, there was almost no change. After 1 year, it could not be confirmed at all, and although the paper base material was dirty, the shape remained almost unchanged. Table 3 shows the above results.

[0024]

[Table 3]

[0025]

According to the invention of claim 1, since the entire laminate has biodegradability, not only the barrier properties are excellent, but also the environmental compatibility is excellent, and it is used as various packaging materials and the like. After use, there is no problem in disposal. Further, according to the invention of claim 2, not only the excellent barrier property is exhibited without impairing the original environmental compatibility of the paper, but also the adhesion between the paper base material and the vapor deposition layer is excellent. The barrier property does not deteriorate. Further, the thickness of the film is set to 1-10.
By specifying to be μm, the original environmental compatibility (biodegradability and disintegration property) of paper is further improved. Further, according to the invention of claim 3, it is possible to promote disintegration into a laminate as compared with the case of a single piece of paper,
Moreover, when this is used as a material for a container or the like, since it has a sealing property due to the thermoplasticity of the biodegradable plastic, it can be effectively subjected to an adhesive processing or the like.

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Claims (7)

[Claims] 1. A laminate comprising a paper base material provided with a metal or metal oxide vapor deposition layer, which is previously deposited on the paper base material surface before vapor deposition.
A barrier laminate comprising a biodegradable plastic laminated. 2. A barrier laminate comprising a paper base material provided with a metal or metal oxide vapor deposition layer, wherein the paper base material is a coated paper having a smooth vapor deposition surface. 3. The barrier laminate according to claim 2, wherein a biodegradable plastic is further laminated on the vapor-deposited layer of metal or metal oxide. 4. The biodegradable plastic has a coating thickness of 1-2.
It is 00 micrometers, The barrier laminated body of Claim 1 or 3 characterized by the above-mentioned. 5. The barrier laminate according to claim 2, wherein clay coated paper is used as the coated paper. 6. The barrier laminate according to claim 2, wherein the clay-coated paper is provided with a resin coating having a thickness of 1 to 10 μm. 7. The barrier laminate according to claim 1 or 3 to 6, wherein the biodegradable plastic is a resin containing lactic acid as a main component.