JP5796335B2 - Laminated body - Google Patents

Description

  The present invention relates to a laminate using a biodegradable film, the laminate strength between a pattern ink part and a stretched film or an unstretched film is sufficient, and the ink adhesion to the biodegradable film is excellent. It is related with the laminated body excellent in.

  As a base material for packaging materials used for packaging foods and non-foods as conventional packaging materials, polyester film, nylon film, and polypropylene film have excellent mechanical strength, durability, and low cost. In many cases, general-purpose plastics such as are used.

In recent years, global warming due to an increase in CO ₂ has become a global problem, and in various industrial fields, technology for reducing CO ₂ emissions into the atmosphere has been actively developed. Particularly in the field of plastic products, plant-derived raw material plastics are attracting attention as carbon neutral materials. Carbon neutral means “neutral with respect to the amount of carbon in the environment” and is absorbed by the carbon dioxide emitted when something is produced or when a series of human activities are performed. This shows the concept that the same amount of carbon dioxide is present.

  For example, regarding the use of materials produced from plant raw materials such as corn, such as polylactic acid, the Japan Bioplastics Association (JBPA) has identified organic resources from the perspective of preventing global warming and reducing the consumption of fossil resources. Biomass plastic products that contain a specified amount or more of plant-derived substances as plastic components and comply with the standards established by this association are certified as “biomass plastic” and permitted to use the symbol mark. Makes it easy to identify biomass plastic products.

  In order to identify and identify biomass plastics, the degree of biomass plastic in the product (raw material, ratio of the biomass-derived components in the biomass plastic composition contained in the product) must be a plastic product of 25 wt% or more, It is very important to increase the biomass material ratio in the packaging material as much as possible (at least 25 wt% or more), considering the burden on the global environment, and it is added to consumers by obtaining the biomass plastic certification mark. Considering that it is recognized as a value, it is a necessary item to be studied in the future.

  In particular, polylactic acid is attracting attention as a material that can be mass-produced from plant raw materials such as corn. In response to the recent increase in interest in environmental problems, the production plant has been upgraded to reduce costs to conventional petroleum-derived plastics. Is expected as an alternative.

  Polylactic acid has a relatively high melting point of about 170 ° C. and has advantages such as high transparency and high elastic modulus. However, it has heat resistance and water resistance due to softening in an environment above the glass transition temperature. It is a material that has disadvantages such as degradation of physical properties due to decomposition and solvent resistance, and research and development for practical application is thriving.

  However, until now, biodegradable films such as polylactic acid films have not been able to solve problems such as low ink adhesion and low laminate strength. As a technique for solving these problems, it has been reported that the application of an anchor agent is effective for improving the adhesion between the polylactic acid film and the ink. And problems such as a decrease in pattern reproducibility occur (see, for example, Patent Documents 1 and 2). In addition, it has been reported that it is possible to improve the laminate strength by using an adhesive of the same component as the biodegradable film, but not only the cost is increased, but the pot life of the liquid is short and unstable. (For example, see Patent Document 3).

JP 2005-313507 A JP 2010-052307 A JP 2008-127403 A

  Therefore, the present invention solves the problems such as low ink adhesion and weak laminate strength of the biodegradable film such as polylactic acid film described above when the biodegradable film is used in a laminate for packaging material. It is an object to obtain a laminate for a packaging material using a useful biodegradable film.

The present invention has been made in consideration of the above problems, and a pattern ink portion (3) is provided on one side of a base material (2) made of a polylactic acid film which is a biodegradable film. A laminate (1) in which a superposed film (5) made of a stretched film or a non-stretched film is laminated on one side provided with a pattern ink portion (3),
There is an adhesive layer between the substrate (2) and the superposed film (5), and the adhesive (4) for forming this adhesive layer is a curing agent containing an isocyanate group of aliphatic hexamethylene diisocyanate. all SANYO comprising been formulated,
Providing a laminate adhesive coating weight of the adhesive layer is characterized that you have been in the range of 0.50~3.0g / m ^2, it is intended to solve the above problems.

  Moreover, in this invention, it is favorable that the lamination strength between the pattern ink part (3) of the said base material (2) and the said overlapping film (5) is 1.0 N / 15mm or more.

  According to the present invention, a laminate using a biodegradable film, the laminate strength between the pattern ink portion and a laminated film made of a stretched film or an unstretched film is sufficient, and the ink to the biodegradable film A laminate having excellent printing appearance can be obtained with excellent ink adhesion without inhibiting adhesion. That is, in the present invention, by selecting aliphatic hexamethylene diisocyanate (HDI), which is the hardest cured film among the isocyanates, as the curing agent for the adhesive, it is possible to suppress coating film shrinkage during lamination. As a result, inhibition of adhesion between the biodegradable film and the ink can be prevented.

Furthermore the amount of adhesive applied 0.50~3.0g / ^{m 2} and a normal (ordinary coating amount: 3.1~4.2g / ^{m 2)} by reducing than, the adhesive coating shrinkage suppression Not only is it possible, but the amount of isocyanate curing agent that penetrates into the pattern ink part of the curing agent is small, so re-curing of the pattern ink part can be prevented. The shrinkage stress can be suppressed to a minimum.

  And also from the result, the adhesiveness between the base material which consists of a biodegradable film, and a pattern ink part, and the fall of the lamination strength between a base material and an overlapping film can be prevented.

It is explanatory drawing which shows the layer structure in embodiment of the laminated body which concerns on this invention in a cross section.

Next, the present invention will be described based on the embodiment shown in FIG.
In the figure, reference numeral 1 denotes a laminate used as a packaging material. As shown in the figure, the laminate 1 has a biodegradable film as a base 2 and an ink layer is formed on one side of the base 2 by printing. Is formed of a stretched film or an unstretched film with an adhesive 4 on one side of the substrate 2 on which the pattern ink portion 3 is provided. The laminated film 5 is laminated and laminated.

(Base material)
The biodegradable substance constituting the biodegradable film used for the substrate 2 has a property that can be decomposed by microorganisms. As a biodegradable substance constituting the biodegradable film,
Poly -L- lactide (poly -L- lactic acid) you are using.

In particular, such poly -L- lactide (poly -L- lactic acid), lactic acid, butyric acid, a film made of (co) polymer or its modified product of lactide is easily available, heat resistance and mechanical strength Since it is excellent, it is preferable.

  The biodegradable film is preferably a film obtained by stretching a biodegradable plastic as a film raw material uniaxially or biaxially. It may have gas barrier properties.

  The film thickness of the substrate 2 of the laminate 1, that is, the thickness of the biodegradable film is preferably 6 to 50 μm, and more preferably 15 to 30 μm.

(Laminated film-stretched film)
As described above, the overlapping film 5 in the laminate 1 is made of a stretched film or an unstretched film. Examples of the stretched film include polyesters (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (nylon-6, nylon-66, etc.), polyvinyl chloride, polyimide, and copolymers of these polymers. A plastic film having heat resistance can be used.

  Regarding the thickness when the superposed film 5 is made of a stretched film, the thickness of the laminated body 1 is 6 to 70 μm considering that the biodegradable film (base material) is 25 wt% or more in the laminate 1. Preferably, 12 to 25 μm is more desirable. Further, for example, additives such as an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, and a colorant can be added, and they are appropriately added as necessary.

  The laminate 1 using a stretched film as the superposed film 5 can be mainly developed into a fusing seal bag or the like.

(Laminated film-unstretched film)
When the laminated film 5 is an unstretched film, examples of the unstretched film include polyolefins such as polyethylene, polypropylene, polybutene and polymethylpentene, polyesters such as polyethylene terephthalate and polycarbonate, nylon, polystyrene, polyvinyl chloride, Polyvinylidene chloride, polyvinyl alcohol, ethylene / vinyl alcohol copolymer, polymethyl methacrylate, ethylene / vinyl acetate copolymer, films made of thermoplastic resins such as biodegradable polyester such as polylactic acid and aliphatic polyester are used. it can.

  Regarding the thickness when the laminated film 5 is made of an unstretched film, the thickness is 6 to 70 μm considering that the biodegradable film (base material) is 25 wt% or more in the laminate 1. Is preferable, and 12 to 25 μm is more desirable.

  The laminate 1 using an unstretched film as the laminated film 5 can be developed into a pillow bag, a gusset bag, a three-way or four-side seal bag, and the like.

(adhesive)
The laminate 1 is formed by laminating the superposed film 5 with an adhesive 4 on one side of the base material 2 having the pattern ink portion 3. Next, the adhesive 4 used for the bonding will be described. Examples of the adhesive for laminating include acrylic, ethylene, vinyl acetate, rubber, and the like, but it is preferable to use a urethane adhesive because it is easy to handle. Urethane adhesives are divided into two-component types that use two-component mixture of a hydroxyl group-containing main agent and an isocyanate group-containing curing agent, and one-component types that use an isocyanate group-containing one alone. From the viewpoint of versatility and adhesive performance, the two-component type is superior.

  The types of isocyanate include aromatic toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), and isophorone diisocyanate (IPDI). Each polyisocyanate is used as a curing agent for the adhesive.

  The hardness of the adhesive as a cured film varies depending on the curing agent used. The order of hardness of the adhesive as a cured film is generally known to be the order of aromatic MDI system> aromatic TDI system> aliphatic IPDI system> aliphatic XDI system> aliphatic HDI system. . (Thus, in order to indicate the order of hardness when using a curing agent, a curing agent comprising a polyisocyanate in each of an aromatic isocyanate and an aliphatic isocyanate is simply used while using the symbols described above. It was written as “... system”.)

  In the present invention, aliphatic HDI (aliphatic HDI-based polyisocyanate) is selected as the curing agent for the above-mentioned adhesive, and the shrinkage of the coating film during lamination can be suppressed. As a result, the substrate (biodegradable film) The adhesion between 2 and the pattern ink part (ink layer) 3 is hardly disturbed.

Furthermore the amount of adhesive applied 0.50~3.0g / ^{m 2} and a normal (ordinary coating amount: 3.1~4.2g / ^{m 2)} by reducing than, the suppression of the same manner as described above coating shrinkage In addition, the amount of isocyanate curing agent that penetrates into the pattern ink layer of the curing agent is small, so that re-curing of the ink layer can be prevented, and as a result, shrinkage between the substrate and the ink that occurs during curing Stress can be minimized.

  And the adhesiveness between the base material (biodegradable film) 2 and the pattern ink part (ink layer) 3 and the laminate between the base material 2 and the superposed film (stretched film or non-stretched film) 5 A decrease in strength can be prevented.

(Pattern ink part)
The pattern ink portion 3 is provided for the purpose of imparting the design properties of any desired pattern, and a two-component curable urethane-based general gravure ink is used. There are no particular restrictions on the constituent material and the formation method of the ink layer that is the pattern ink section 3, for example, a colorant such as an organic or inorganic dye or pigment is dissolved in an appropriate solvent together with an appropriate binder resin. Alternatively, a dispersed printing ink or coating agent can be provided by printing or coating by an appropriate printing method or coating method.

  As a method for joining the base material (biodegradable film) 2 and the laminated film (stretched film or non-stretched film) 5, any one of wet lamination method, dry lamination method, and non-solvent dry lamination method is used. can do.

  The Example and comparative example of this invention were produced, and both were compared and examined. The results are shown below.

Example 1
A dry laminating method using a polylactic acid film (PLA) having a thickness of 15 μm on which pattern printing has been applied and an unstretched polypropylene film (CPP) having a thickness of 20 μm (FHK2 manufactured by Futamura Chemical Co., Ltd.). Was laminated to obtain a laminate (laminate 1).

The dry laminate uses a urethane-based two-component curable adhesive in which an aliphatic ester-based main component and a curing agent containing an aliphatic HDI-based isocyanate group are combined, and the coating amount is about 2.0 g / m ² . Coated so that.

(Example 2)
A laminate was obtained in the same manner as in Example 1 except that the amount of adhesive applied was 3.0 g / m ² .

(Example 3)
A laminated product was obtained in the same manner as in Example 1 except that an aliphatic ether main agent was used instead of the aliphatic ester main agent in the adhesive.

Example 4
A laminated product was obtained in the same manner as in Example 1 except that a 20 μm-thick stretched polypropylene film (OPP) (FORTA Chemical Industries, Ltd. FOR) was used instead of the unstretched polypropylene film (CPP).

(Example 5)
A laminated product was obtained in the same manner as in Example 1 except that the amount of adhesive applied was 0.8 g / m ² .

(Comparative Example 1)
A laminate was obtained in the same manner as in Example 1, except that a curing agent containing an aromatic TDI isocyanate group was used instead of the curing agent containing an aliphatic HDI isocyanate group.

(Comparative Example 2)
A laminate was obtained in the same manner as in Example 1 except that a curing agent containing an aliphatic IPDI isocyanate group was used instead of the curing agent containing an aliphatic HDI isocyanate group.

  As a performance evaluation, the laminate strength was measured. Specifically, samples obtained by cutting the samples into a width of 15 mm were obtained from each of the above Examples 1, 2, 3, 4, 5 and Comparative Examples 1 and 2, and this was obtained from Tensilon (manufactured by A & D Co., Ltd.). : Measured according to JIS-Z1707 using a tensile / compression tester RTF-1250). The results are shown in Table 1.

  As shown in Table 1, it was confirmed that the laminate strength was good in the ink portions in Examples 1 to 5 as performance evaluation. Therefore, in the laminate using the biodegradable film in the present invention, the laminate strength between the pattern ink part and the overlay film is sufficient, and the ink adhesion to the biodegradable film is excellent, and the printed appearance It was confirmed that the laminate was excellent.

DESCRIPTION OF SYMBOLS 1 ... Laminated body 2 ... Base material 3 ... Pattern ink part 4 ... Adhesive 5 ... Overlay film

Claims (2)

On one side of the base material (2) made of a polylactic acid film which is a biodegradable film , the pattern ink part (3) is provided, and on one side of the base material (2) where the pattern ink part (3) is provided, A laminate (1) in which a laminated film (5) made of a stretched film or an unstretched film is laminated,
There is an adhesive layer between the substrate (2) and the superposed film (5), and the adhesive (4) for forming this adhesive layer is a curing agent containing an isocyanate group of aliphatic hexamethylene diisocyanate. all SANYO comprising been formulated,
Laminate adhesive application amount of the adhesive layer is characterized that you have been in the range of 0.50~3.0g / ^{m 2.} The laminate according to claim 1, wherein the laminate strength between the pattern ink portion (3) of the substrate (2) and the superposed film (5) is 1.0 N / 15 mm or more.

Images