JP5446442B2 - Laminated body - Google Patents

Description

  The present invention is a laminate in which at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, and in particular, various strengths having excellent laminate strength and containing volatile substances. The present invention relates to a laminate in which the laminate strength between the plastic substrate and the sealant layer does not decrease even when the permeable content acts.

  Conventionally, as a packaging material for packaging foods, pharmaceuticals, and the like, for example, laminates having a layer configuration of paper layer / polyethylene layer / aluminum foil layer / polyester layer / sealant layer have been widely used. The lamination of the polyester layer and the sealant layer of such a laminate is usually performed by applying a two-component curable polyurethane anchor coat agent on the polyester film and then extruding the sealant layer. . Such a laminate has an appropriate laminate strength and gas barrier property, and is widely used as a packaging material for packaging foods and pharmaceuticals.

  However, when a laminate having the above-described configuration is used as a packaging material and a volatile substance such as an acidic substance, an alkaline substance, a fragrance, a surfactant, or an organic solvent is packaged, the anchor is anchored by the strong osmotic force of the volatile substance. The coating agent was adversely affected, and the laminate strength between the plastic substrate and the sealant layer decreased with time, resulting in delamination.

  Such delamination is a two-component curable polyurethane in which an anchor coat agent used in the lamination process in the production process of a laminate having the above-described structure, for example, a main component such as polyester polyol and a curing agent composed of an isocyanate compound is blended. The strong penetrating contents as described above have an adverse effect on the adhesive layer composed of the anchor coating agent of the system, and the main resin component of the adhesive layer is swollen or the molecular weight is lowered, and the cohesive force of the adhesive layer is reduced. It is thought to happen at times.

  Under such circumstances, in a laminate in which at least a sealant layer is provided on a plastic substrate via an adhesive layer, even if various strongly permeable contents containing a volatile substance act, There is a strong demand for the development of a laminate that can be suitably used for packaging materials without deteriorating the laminate strength between the material and the sealant layer.

Under such circumstances, various studies have been made on adhesives used in the laminating process during the manufacturing process of the laminate having the above-described configuration. For example, in a laminate in which at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, a main component such as polyester polyol and a curing agent composed of an isocyanate compound are blended as an adhesive constituting the adhesive layer. By using a liquid curable polyurethane-based material having a ratio between the main agent and the curing agent of 1:99 to 15:85, particularly, excellent laminate strength is provided and a volatile substance is contained. various strong osmotic contents were proposed Tsu there was so not to lower the lamination strength of the plastic substrate and the sealant layers also act (e.g., see Patent Document 1.).

However, the above-mentioned adhesives have poor leveling properties (wetting properties) with respect to plastic substrates, and when an adhesive layer is formed by ultra-thin coating, there are alternating portions where sufficient laminate strength can be obtained and other portions that do not. As a result, the laminate strength may become uneven. In addition, as an advantage of forming the adhesive layer by ultra-thin coating, the adhesive layer becomes very thin, so that the drying time is shorter, the reaction time is shorter, and it can be produced at a lower cost. However, when it was used as an adhesive constituting the adhesive layer of the laminate having the above-described structure, an adhesive layer capable of exhibiting the desired effect could not be formed by ultra-thin coating.

JP 2006-187908 A

  The present invention has been made in order to solve the above-described conventional problems, and the object of the present invention is a laminate in which at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate. In particular, the laminate strength between the plastic substrate and the sealant layer does not decrease even when various strong penetrating contents having excellent initial laminate strength and containing volatile substances act, and these It is an object of the present invention to provide a laminate in which the excellent characteristics can be exhibited even with an extremely thin adhesive layer.

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, and the adhesive layer is 85% by weight or more bifunctional or higher. of an isocyanate compound having an isocyanate group, a polydimethylsiloxane compound which is soluble in the 0.01 to 0.5 wt% ethyl acetate, as the remaining components, a polyester polyol, polyether polyol, those in addition to the acrylic polyol A laminate comprising a polyester polyurethane polyol and a polyether polyurethane polyol as a base.

  The invention according to claim 2 is the laminate according to claim 1, wherein the isocyanate compound having a bifunctional or higher functional isocyanate group is a bifunctional isocyanate monomer, or an adduct, burette, or isocyanurate type 3 thereof. It is characterized by being any of the functionalized monomer derivatives.

  Furthermore, the invention according to claim 3 is the laminate according to claim 1 or 2, wherein the adhesive layer has a thickness of 1 μm or less.

  The laminate of the present invention has at least a three-layer structure of a plastic substrate, an adhesive layer, and a sealant layer, and the adhesive layer is not affected by strongly permeable contents, and is a very thin and dense layer. Therefore, it exhibits excellent laminate strength for plastic substrates. Therefore, even if it is used as a packaging material for storing various strongly permeable contents containing volatile substances such as acidic substances, alkaline substances, fragrances, surfactants, organic solvents, etc. Laminate strength does not decrease and delamination does not occur. Moreover, since the leveling property (wetting property) of the adhesive layer with respect to the plastic substrate is excellent, the above-described excellent characteristics can be surely exhibited even with a thin adhesive layer of about 1 μm or less obtained by ultra-thin coating. Can do.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the laminate of the present invention, at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, and the adhesive layer has an isocyanate compound having a bifunctional or higher isocyanate group of 85% by weight or more, and 0.01 It is characterized by comprising ~ 0.5% by weight of a polydimethylsiloxane compound.

Plastic substrates include polyester film normal type, copolymer type, and easy adhesion type, nylon film normal type, easy adhesion type, and polypropylene film non-static type and static type. Various types can be used.
Moreover, an aliphatic polyester film and an aliphatic aromatic polyester film can also be used. Furthermore, as a constituent material of the plastic substrate, a polymer mainly composed of lactic acid, for example, a homopolymer composed only of lactic acid, or a monomer other than lactic acid based on lactic acid, for example, oxyacids such as malic acid and glycolic acid, Copolymers obtained by copolymerizing 3-hydroxybutyrate, 3-hydroxyvalerate, caprolactone, dicarboxylic acids such as succinic acid and adipic acid and diols such as ethylene glycol and 1,4-butanediol, or mixtures thereof Can be used. In addition, copolymers of dicarboxylic acids such as succinic acid, adipic acid and terephthalic acid and diols such as ethylene glycol and 1,4-butanediol, such as polyethylene terephthalate-succinate with terephthalic acid, polybutylene adipate -Terephthalate, polytetramethylene adipate-terephthalate, etc. can also be used.
And, such a plastic base material is subjected to surface treatment such as corona treatment or plasma treatment on one surface thereof, and an adhesive layer described later can be stably formed thereon. preferable. Further, the thickness is not particularly limited.

  Moreover, as a plastic substrate, the vapor deposition film which provided the vapor deposition thin film layer which consists of inorganic oxides on the above plastic films etc. can also be used. The vapor-deposited thin film layer may be any vapor-deposited thin film such as aluminum oxide, silicon oxide, magnesium oxide, tin oxide, or a mixture thereof, as long as it has a gas barrier property against oxygen or water vapor. Among them, a vapor-deposited thin film layer made of any one of aluminum oxide, silicon oxide, and magnesium oxide is preferable because it is excellent in terms of oxygen permeability and water vapor permeability, but is not necessarily limited to those made of the above-described constituent materials. Absent.

  When providing a vapor-deposited thin film layer made of an inorganic oxide on a plastic film, etc., corona treatment, low-pressure plasma treatment, atmospheric pressure plasma treatment, flame treatment as pre-treatment for improving adhesion with the vapor-deposited thin film layer, Surface treatment such as ion bombardment treatment, and further surface treatment such as chemical treatment and solvent treatment may be performed. Moreover, you may provide the thin film of the primer for vapor deposition which has an inorganic compound on a plastic film as needed. Furthermore, a gas barrier coating layer having an inorganic compound may be provided on the vapor-deposited thin film layer in order to impart a high level of gas barrier properties comparable to that of a metal foil.

  The adhesive layer laminated on the plastic substrate having such a structure is composed of an isocyanate compound having a bifunctional or higher functional group of 85% by weight or more and a polydimethylsiloxane compound of 0.01 to 0.5% by weight. Is. In addition to the polyester polyol, the polyether polyol, and the acrylic polyol, it is preferable to use a polyester polyurethane polyol, a polyether polyurethane polyol, or the like based on these as the remaining component of about 15% by weight or less. The compound is not limited to these compounds as long as it is not a compound that becomes too gelable and readily gels and has a good compatibility with an isocyanate compound having an isocyanate group.

Examples of the isocyanate compound having an isocyanate group constituting a part of the adhesive layer include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4, Examples thereof include various diisocyanate monomers such as 4′-diphenylmethane diisocyanate and hydrogenated products thereof. In addition, adduct types obtained by reacting these diisocyanate monomers with trifunctional active hydrogen-containing compounds such as trimethylolpropane and glycerol, burette types obtained by reacting with water, and trimers utilizing self-polymerization of isocyanate groups ( A trifunctional derivative such as an isocyanurate type or a polyfunctional derivative higher than that may be used.

  The polydimethylsiloxane compound is a compound having polydimethylsiloxane as a basic skeleton, a typical dimethylsiloxane polymer, a methylphenylsiloxane polymer in which a part of the methyl group is substituted with a phenyl group, and the methyl group. And a methylhydrogensiloxane polymer in which a part of is substituted with a hydrogen atom. Further, an alkyl-modified siloxane polymer in which a part of the methyl group of the dimethylsiloxane polymer is substituted with an alkyl group, a higher fatty acid-modified siloxane polymer substituted with a higher fatty acid, a fluorine-modified siloxane polymer substituted with a functional group having a fluorine group, An amino-modified siloxane polymer substituted with a functional group having an amino group, an epoxy-modified siloxane polymer substituted with a functional group having an epoxy group, a carboxyl-modified siloxane polymer substituted with a functional group having a carboxyl group, a functional group having a hydroxyl group Examples of the diluting solvent for the isocyanate compound having an isocyanate group are mainly vinegar, such as a hydroxyl group-containing siloxane polymer substituted with a methacryl-modified siloxane polymer substituted with a functional group having a methacryl group. Since the ethyl is used, polydimethylsiloxane compounds dissolved in ethyl acetate can be preferably used.

  Since these polydimethylsiloxane compounds have an extremely small surface tension compared to other liquids, polydimethylsiloxane is added to an isocyanate compound having a bifunctional or higher isocyanate group of 85% by weight or more constituting a part of the adhesive layer. By adding the compound in a proportion of 0.01 to 0.5 parts by weight, the leveling property (wetting property) of the adhesive layer to the plastic substrate is remarkably improved, and the adhesive layer has a uniform layer thickness by ultra-thin coating. Can be formed.

  The addition amount of the polydimethylsiloxane compound may be 0.01 to 0.5% by weight, but is preferably about 0.01 to 0.2% by weight. Addition exceeding 0.5% by weight is an excessive amount for improving the leveling property (wetting property) of the adhesive layer with respect to the plastic substrate, and causes a decrease in cohesive strength of the adhesive layer after the reaction.

  When the ratio of the isocyanate compound having a bifunctional or higher functional isocyanate group constituting the adhesive layer is made rich in a polyester polyol such as a mixture of 90% by weight of a polyester polyol and 10% by weight of an isocyanate compound, the strongly penetrating contents act. As a result, the polyester polyol swells or the molecular weight decreases, and the cohesive force of the adhesive layer formed therefrom decreases, so that the laminate strength between the plastic substrate and the sealant layer decreases with time. Therefore, an isocyanate compound-rich adhesive layer is formed, that is, the ratio of the isocyanate compound is 85% by weight or more. More preferably, it is 90% by weight or more.

The adhesive layer having such a structure comprises, on a plastic substrate, 85% by weight or more of an isocyanate compound having a bifunctional or higher functional isocyanate group and 0.01 to 0.5% by weight of a polydimethylsiloxane compound in ethyl acetate. What is necessary is just to apply and provide the thin film of the coating liquid which contains by solid content ratio 0.01-3 weight%, Preferably 0.05-2 weight%. In addition, it is preferable that the thickness of the adhesive layer is thin. Specifically, the adhesive layer may be provided so as to be a thin layer having a thickness of about 1 μm or less when dried.
By making the adhesive layer very thin, the reaction time and drying time in the adhesive layer at the time of producing the laminate can be shortened, and it can be produced at low cost. Moreover, the laminate of the present invention has excellent leveling properties (wetting properties) even when the thickness of the adhesive layer constituting a part thereof is less than 1 μm, and thus can ensure excellent laminate strength. The excellent laminate strength does not decrease even when a strong penetrating substance acts.

  On the other hand, as a sealant layer laminated | stacked on an contact bonding layer, the layer which consists of polyolefin resin, such as polyethylene resin and a polypropylene resin, can be mentioned as a specific example. As a material for forming such a sealant layer, furthermore, high density polyethylene, low density polyethylene, medium density polyethylene, ethylene-based resins such as ethylene-α olefin copolymer, homo-block / random polypropylene resins, Propylene-based resins such as propylene-α olefin copolymers, ethylene-α, β unsaturated carboxylic acid copolymers such as ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers, ethylene-methyl acrylate and ethylene -Ethylene-α, β esterified product of ethylene-α, β-unsaturated carboxylic acid copolymer such as ethyl acrylate, ethylene-methyl methacrylate, ethylene-ethyl methacrylate, ethylene-α, wherein carboxylic acid moiety is crosslinked with sodium ion, zinc ion , Β-unsaturated carboxylic acid copolymer ionic cross-linked product, ethyl -Epoxy compound-modified polyolefin such as acid anhydride-modified polyolefin, ethylene-glycidyl methacrylate copolymer represented by terpolymer such as ethylene-maleic anhydride graft copolymer and ethylene-ethyl acrylate-maleic anhydride Specific examples thereof include a single resin or a blend of two or more resins selected from ethylene-vinyl acetate copolymers.

  Also, aliphatic polyesters and aliphatic aromatic polyesters can be used. More specific examples include copolymers of dicarboxylic acids such as succinic acid and adipic acid and diols such as ethylene glycol and 1,4-butanediol (for example, polyethylene succinate, polybutylene succinate, poly Butylene succinate-adipate), microbial-produced polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate-hexanoate, polymers of oxyacids such as lactic acid, malic acid, glycolic acid or copolymers thereof , Polycaprolactone, polycaprolactone-butylene succinate, aliphatic polyester such as polyester having amide bond, polyester having carbonate bond, or polyethylene terephthalate-succinate having terephthalic acid, polybene Ren'ajipeto - terephthalate, polytetramethylene adipate - terephthalate and alone or two or more of the blend of resin selected from the aliphatic-aromatic polyesters, and the like. To these constituent materials, various additives (such as an antioxidant, a tackifier, a filler, and various fillers) may be added as necessary.

  And the laminated body of such a structure is, for example, 85% by weight or more of an isocyanate compound having a bifunctional or higher functional isocyanate group and 0.01 to 0.5% by weight of a polydimethylsiloxane compound on a plastic substrate. In the coating part of the extrusion laminating machine, a thin film of a coating solution containing 0.01 to 3% by weight, preferably 0.05 to 2% by weight, in solid content of ethyl acetate is applied so that the thickness is 1 μm or less. After coating and drying, it can be obtained, for example, by extruding polyethylene or the like from a T die and laminating a sealant layer.

  According to the manufacturing method as described above, various strong penetrating contents having good initial laminate strength between the plastic substrate and the adhesive layer and between the adhesive layer and the sealant layer and containing volatile substances act. However, it is possible to obtain a laminate in which the laminate strength between the plastic substrate and the adhesive layer and between the adhesive layer and the sealant layer does not decrease. Moreover, since the leveling property (wetting property) of the adhesive layer with respect to the plastic substrate is excellent, it is possible to ensure an excellent laminate strength even when the adhesive layer is extremely thin of about 1 μm or less, and the excellent laminate. The strength does not decrease even when various strongly permeable contents act.

As described above, the laminate of the present invention has been described with an example of a three-layer structure of a plastic base material / adhesive layer / sealant layer, but in order to further ensure the permeation or diffusion of various strongly permeable contents to the outside. For example, a laminate composed of PET / adhesive layer / aluminum foil / adhesive layer / plastic substrate / adhesive layer / sealant layer may be used, and an aluminum foil layer may be provided outside the plastic substrate. Furthermore, in consideration of the use as a packaging material, a configuration in which another layer is interposed may be used for the purpose of improving the rigidity and durability required for the packaging material. Examples of the present invention will be described below.

  As a plastic substrate, a polyethylene terephthalate film with a thickness of 12 μm and subjected to corona treatment on one surface is used. On this corona treatment surface, isophorone diisocyanate monomer and dimethylsiloxane having a solid content ratio of 0.01% by weight are used. The polymer was added to ethyl acetate, and a thin film of a coating solution having a solid content ratio of 0.5% by weight was applied, and then dried in an oven to form an adhesive layer. Then, a low-density polyethylene having a thickness of 40 μm is extruded on the adhesive layer by extrusion lamination at a temperature under the die of 320 ° C. and a processing speed of 80 m / min to laminate a sealant layer, and then subjected to aging at 50 ° C. for 3 days. Thus, a laminate according to Example 1 was obtained. The thickness of the adhesive layer after drying was 50 nm.

  As the coating liquid for forming the adhesive layer, adduct type of tolylene diisocyanate and polyester polyol are mixed so as to be 90:10 (weight ratio), and the solid content ratio is 0.01% with respect to 100% by weight of this mixture. % Methylphenylsiloxane polymer, a coating liquid having a solid content ratio of 0.5% by weight was used, and an ethylene-methacrylic acid copolymer was used as a constituent material of the sealant layer. Thus, a laminate according to Example 2 was obtained. The thickness after drying of the adhesive layer was 50 nm, and the temperature under the die when the sealant layer was formed by extrusion extrusion onto the adhesive layer was 280 ° C.

  A nylon film having a thickness of 15 μm is used as a plastic substrate, and an adduct type of isophorone diisocyanate and a polyester polyol are mixed as a coating liquid for forming an adhesive layer so as to be 90:10 (weight ratio). Add a methyl hydrogen siloxane polymer with a solid content ratio of 0.3% by weight to the weight percent, and use a coating solution with a solid content ratio of 0.7% by weight. Zinc ionomer is used as the constituent material of the sealant layer. A laminate according to Example 3 was obtained in the same manner as in Example 1 except that it was used. The thickness of the adhesive layer after drying was 70 nm, and the temperature under the die when the sealant layer was formed by extrusion extrusion onto the adhesive layer was 300 ° C.

  A nylon film having a thickness of 15 μm is used as a plastic substrate, and a burette type of hexamethylene diisocyanate and a polyether polyol are mixed so as to be 85:15 (weight ratio) as a coating liquid for forming an adhesive layer, A fluorine-modified siloxane polymer in which a part of methyl groups of a dimethylsiloxane polymer having a solid content ratio of 0.3% by weight with respect to 100% by weight of this mixture is substituted with a functional group having a fluorine group is added, and the solid content ratio is reduced to 0. A laminate according to Example 4 was obtained in the same manner as in Example 1 except that a coating liquid of 7% by weight was used and random polypropylene was used as a constituent material of the sealant layer. The thickness after drying of the adhesive layer was 70 nm, and the temperature under the die when the sealant layer was formed on the adhesive layer by extrusion lamination was 275 ° C.

A polylactic acid film having a thickness of 20 μm is used as a plastic substrate, and an isocyanurate type of hexamethylene diisocyanate and an acrylic polyol are mixed as an application liquid for forming an adhesive layer at 85:15 (weight ratio), An amino-modified siloxane polymer in which a part of methyl groups of a dimethylsiloxane polymer having a solid content ratio of 0.5% by weight with respect to 100% by weight of this mixture is substituted with a functional group having an amino group is added, and the solid content ratio is 1 A laminate according to Example 5 was obtained in the same manner as in Example 1 except that the coating solution was 0.0% by weight and polybutylene succinate was used as the constituent material of the sealant. The thickness after drying of the adhesive layer was 100 nm, and the temperature under the die when the sealant layer was formed by extrusion extrusion onto the adhesive layer was 280 ° C.

  In the same manner as in Example 1, except that an adduct type of tolylene diisocyanate was used as a coating liquid for forming an adhesive layer, and a coating liquid having a solid content ratio of 0.5% by weight was used. Thus, a laminate according to Example 6 was obtained. The thickness of the adhesive layer after drying was 50 nm.

  As the coating liquid for forming the adhesive layer, a coating liquid in which an adduct type of isophorone diisocyanate and a polyester polyol were mixed so as to be 85:15 (weight ratio) and a solid content ratio was 0.7% by weight was used. Except for the above, a laminate according to Example 7 for comparison was obtained in the same manner as in Example 1. The thickness of the adhesive layer after drying was 70 nm.

  A nylon film with a thickness of 15 μm is used as a plastic substrate, and an adduct type of xylylene diisocyanate and a polyether polyol are mixed as a coating liquid for forming an adhesive layer so as to be 20:80 (weight ratio), and solid Example for comparison in the same manner as in Example 1 except that a coating liquid having a fraction of 1.0% by weight was used and an ethylene-methacrylic acid copolymer was used as a constituent material of the sealant layer. A laminate according to No. 8 was obtained. The thickness after drying of the adhesive layer was 100 nm, and the temperature under the die when the sealant layer was formed by extrusion extrusion onto the adhesive layer was 280 ° C.

  A pouch was prepared using each of the laminates of Examples 1 to 5 and 8 obtained by the above-described production method and sufficient initial lamination strength was obtained, and a poultice (volatile) was prepared as the contents. And a bath agent (containing a fragrance component as a volatile strong osmotic substance), sealed, and left in a constant temperature room at 40 ° C.

  After 3 months, these pouches are removed from the temperature-controlled room, and the laminate strength [N / 15mm] between the various plastic substrates and the sealant layer of each pouch is measured and compared with the initial laminate strength in the pouch before entering the temperature-controlled room. did. The measurement conditions of the laminate strength at this time were T-type peeling with a sample width of 15 mm and a peeling speed of 300 mm / min. Table 1 summarizes the measurement results of the laminate strength before and after the constant temperature input.

  As is clear from Table 1, the initial laminate strength between the various plastic substrates and the sealant layers of the laminates according to Examples 1 to 5 was so strong that the sealant was broken. Further, even in the pouch stored with a poultice containing a volatile substance and a bath agent and stored at 40 ° C. for 3 months, the laminate strength did not change, and the initial laminate strength was sufficiently maintained.

  On the other hand, the initial laminate strength between the plastic base material and the sealant layer of the laminate according to Examples 6 and 7 is poor in leveling property (wetting property) with respect to the plastic base material of the adhesive layer, and is sufficiently laminated. It was found that the portion where the strength was obtained and the portion where the strength was not obtained were alternately present and the laminate strength was nonuniform, which was not suitable for use as a packaging material.

  Moreover, since the adhesive layer of the laminate according to Example 8 is rich in polyether polyol and has good leveling properties (wetability) with respect to the plastic substrate, the initial laminate strength between the plastic substrate and the sealant layer is used. Was strong enough to show the sealant running out, but in the pouch stored for 3 months at 40 ° C. with a poultice or bathing agent containing volatile substances, the laminate strength was significantly reduced. It has been found that the contents containing volatile substances such as bath agents are not suitable for use in packaging materials.

Claims (3)

At least an adhesive layer and a sealant layer are provided in this order on the plastic substrate, and the adhesive layer has an isocyanate compound having a bifunctional or higher isocyanate group of 85% by weight or more, and 0.01 to 0.5% by weight Polydimethylsiloxane compound dissolved in ethyl acetate , and the remaining components include polyester polyol, polyether polyol, acrylic polyol, polyester polyurethane polyol based on these, and polyether polyurethane polyol. Laminated body.   The isocyanate compound having a bifunctional or higher functional isocyanate group is any one of a bifunctional isocyanate monomer or a derivative of a trifunctional monomer of adduct, burette or isocyanurate type. 1. The laminate according to 1.   The laminate according to claim 1, wherein the adhesive layer has a thickness of 1 μm or less.