JP2008290359A - Method for producing laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing at least a laminate comprising an adhesive layer and a sealant layer in this order on a plastic substrate, which possesses excellent laminate strength, maintains the laminate strength between the plastic substrate and the sealant layer even the laminate is affected by various highly permeable contents including volatile substances, has satisfactory and stable laminate strength, and, in particular, can dispense with long hours aging after laminate processing. <P>SOLUTION: This laminate comprises at least an adhesive layer and a sealant layer formed on the plastic substrate in this order, wherein the thickness of the adhesive layer is 1 μm or less, and the adhesive layer comprises 85 wt.% or more of an isocyanate compound. The method for producing the laminate comprises forming a sealant layer and laminating by an extrusion lamination process, followed by a heat and moisturizing treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method for producing 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, has a superior laminate strength and contains a volatile substance. The present invention relates to a method for producing a laminate in which the laminate strength between a plastic substrate and a sealant layer does not decrease even when various strong permeable contents act.

  Conventionally, as a packaging material for packaging foods and pharmaceuticals, for example, a laminate in which each layer is laminated, such as a paper layer / polyethylene layer / aluminum foil layer / polyester layer / sealant layer, has been widely used. . The polyester layer (plastic base material) and sealant layer of this laminate are usually bonded to a polyester layer made of a polyester film by applying an adhesive (anchor coating agent) such as a two-component curable polyurethane as an adhesive layer. After that, it was performed by extrusion laminating the sealant layer. And such a laminated body has moderate lamination strength, gas barrier property, etc., and is widely used as a packaging material for packaging foods and pharmaceuticals.

  However, the contents packaged by the packaging material may contain volatile substances such as acidic substances, alkaline substances, fragrances, surfactants, and organic solvents. When a laminate obtained by using an adhesive such as the above-mentioned two-component curable polyurethane is used as a packaging material and these contents are packaged, the adhesive layer is adversely affected by the strong penetration of volatile substances. In some cases, the laminate strength between the plastic substrate and the sealant layer decreases with time, resulting in delamination.

  In this delamination, the adhesive layer composed of a two-component curable polyurethane system in which a main component such as polyester polyol and a curing agent composed of an isocyanate compound are blended, the swelling of the main component resin component is caused by the above-mentioned strong penetrating volatile contents. This is considered to be caused by a decrease in molecular weight and a decrease in cohesive force.

  Under such circumstances, in a laminate in which a sealant layer is provided on a plastic substrate via at least an adhesive layer, even if various strongly permeable contents containing a volatile substance act, There has been a strong demand for the development of a laminate that can be suitably used for packaging materials, in which the laminate strength between the material and the sealant layer does not decrease.

  In Patent Document 1, at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, and the adhesive layer is a two-component curable polyurethane in which a main agent such as polyester polyol and a curing agent composed of an isocyanate compound are blended. It is a laminate that is rich in isocyanate compounds, and is particularly excellent in laminate strength, even when various strongly permeable contents containing volatile substances act. A laminate has been proposed in which the laminate strength between the sealant layers does not decrease.

However, when the adhesive layer is rich in an isocyanate compound, unreacted isocyanate groups always remain after lamination. Since the urethane bond formed by the reaction between the hydroxyl group derived from the main agent and the isocyanate group derived from the curing agent has a relatively high formation rate, a stable laminate strength is exhibited by aging in a short time after lamination. However, since the urea bond formed by the reaction of an isocyanate group and water has a very slow formation rate, for example, long-time heat aging of 3 days at 50 ° C. after lamination is indispensable. The remaining unreacted isocyanate group reacts with water depending on the humidity environment, so even after several days of heat aging after laminating, the laminate strength varies, and it is necessary to extend the aging time. There was a case.
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 to produce a laminate in which at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate. This method has excellent laminating strength and does not decrease the laminating strength between the plastic substrate and the sealant layer even when various strongly penetrating contents containing volatile substances act, especially laminating. An object of the present invention is to provide a method for producing a laminate having a stable and sufficient laminate strength without requiring long-term aging later.

  The present invention is for solving the above-mentioned problems. In the invention according to claim 1 of the present invention, at least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, and the thickness of the adhesive layer is Is a 1 μm or less, adhesive layer is composed of 85% by weight or more of an isocyanate compound, a sealant layer is formed by an extrusion laminating method, laminated, and then heated and humidified.

  The invention according to claim 2 of the present invention is the method for producing a laminate according to claim 1, wherein the isocyanate compound is a bifunctional isocyanate monomer, or a trifunctional monomer of adduct, burette, or isocyanurate type. It is a manufacturing method of the laminated body characterized by being a derivative | guide_body of this.

    According to the method for producing a laminate of the present invention, it is possible to produce a laminate having a stable and sufficient laminate strength without requiring long-term aging after lamination.

  The laminate according to the production method of the present invention is composed of at least three layers of a plastic substrate layer, an adhesive layer, and a sealant layer, and the adhesive layer is not affected by the strong penetrating contents and is very thin and dense. As a result, the laminate strength is excellent for plastic substrates. For example, a laminate between a plastic substrate and a sealant layer even when used as a packaging material for storing various strongly permeable contents containing volatile substances such as acidic substances, alkaline substances, perfumes, surfactants, and organic solvents Strength does not decrease.

  Hereinafter, a manufacturing method of the present invention is explained in detail based on one embodiment.

  As the plastic substrate constituting the laminate of the present invention, polyester film normal type, copolymer type, easy adhesion type, etc., nylon film normal type, easy adhesion type, etc., polypropylene film non-static type, static prevention Various types such as types can be used. Moreover, an aliphatic polyester film and an aliphatic aromatic polyester film can also be used. Specific examples of the constituent material include a polymer containing lactic acid as a main component, for example, a homopolymer consisting only of lactic acid, a monomer other than lactic acid as a main component, such as oxyacids such as malic acid and glycolic acid, 3- Uses copolymers of hydroxybutyrate, 3-hydroxyvalylate, caprolactone, copolymers of dicarboxylic acids such as succinic acid and adipic acid and diols such as ethylene glycol and 1,4-butanediol, or mixtures thereof Is possible. In addition, copolymers of dicarboxylic acids such as succinic acid, adipic acid and terephthalic acid with 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. Any type of film can be used as a substrate as long as a surface treatment such as a corona treatment is performed on one of the surfaces and an adhesive layer can be stably formed on the surface. Further, the thickness is not particularly limited.

  Moreover, the film which provided the vapor deposition thin film layer which consists of inorganic oxides on the said plastic base material can also be used. The vapor-deposited thin film layer is made of a vapor-deposited film such as aluminum oxide, silicon oxide, magnesium oxide, tin oxide, or a mixture thereof, and may be any layer having gas barrier properties such as oxygen and water vapor. Among these, aluminum oxide, silicon oxide, and magnesium oxide are particularly preferable because of low oxygen permeability and water vapor permeability.

  When providing a vapor-deposited thin film layer made of an inorganic oxide on the plastic substrate, in order to improve the adhesion with the vapor-deposited thin film layer, as a pretreatment, corona treatment, low-pressure plasma treatment, atmospheric pressure plasma treatment, flame treatment, Surface treatment such as ion bombardment treatment may be performed, and surface treatment such as chemical treatment or solvent treatment may be performed. Moreover, it is possible to select the vapor deposition primer which has an inorganic compound according to various plastic base materials 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 property comparable to that of a metal foil.

  The adhesive layer laminated on the plastic base material has a thickness of 1 μm or less, is composed of 85% by weight or more of the isocyanate compound, and may be a single isocyanate compound. In the case of a mixture, the remaining 15% by weight or less is not a compound that is too reactive with an isocyanate group and quickly gels, and may be a compound having good compatibility with an isocyanate compound, preferably In addition to polyester polyols, polyether polyols, and acrylic polyols, polyester polyurethane polyols and polyether polyurethane polyols based on these can be used.

  Examples of the isocyanate compound include various diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and hydrogenated products thereof. Specific examples thereof include system monomers. 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 can be used.

  Regarding the ratio of the isocyanate compound constituting the adhesive layer, for example, when a polyester polyol-rich adhesive layer is formed, such as a mixture of 90% by weight of polyester polyol and 10% by weight of isocyanate compound, the strongly penetrating contents have an adverse effect. The polyester polyol is swollen and the molecular weight is lowered, and the cohesive force of the adhesive layer is lowered, so that the laminate strength between the base material and the sealant layer is lowered with time. Therefore, it is necessary to form an adhesive layer rich in an isocyanate compound, and the adhesive layer is not affected by the strongly penetrating contents when the proportion of the isocyanate compound is 85% by weight or more, preferably 90% by weight or more. Is obtained.

As a method for forming this adhesive layer, a simple substance or a mixture consisting of 85% by weight or more of an isocyanate compound is formed on a plastic substrate at a solid content of 0.05 to 5 wt%, preferably 0.1 to 2 wt%. The coating liquid containing is applied and provided. Further, the adhesive layer is preferably thin, and specifically, the adhesive layer is provided so as to be a thin layer having a thickness of 1 μm or less when dried. If it is 1 μm or more, it takes a long time to dry the solvent, and the development of resistance to strongly permeable contents may become difficult due to insufficient drying.

  The sealant layer is a layer made of polyethylene resin or polypropylene resin. Specifically, high density polyethylene, low density polyethylene, medium density polyethylene, ethylene resins such as ethylene-α olefin copolymer, homo-block / random polypropylene resins, propylene-α olefin copolymer, etc. Propylene resin, ethylene-α, β unsaturated carboxylic acid copolymer such as ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer, ethylene-methyl acrylate, ethylene-ethyl acrylate, ethylene-methacrylic acid Esterified products of ethylene-α, β unsaturated carboxylic acid copolymers such as methyl acrylate and ethylene-ethyl methacrylate, ethylene-α, β unsaturated carboxylic acid copolymer with carboxylic acid moiety cross-linked with sodium ion and zinc ion Ionic cross-linked products of polymers, ethylene-maleic anhydride graft copolymer and ethylene-acrylic Resin unit selected from acid anhydride-modified polyolefins typified by terpolymers such as ethyl-maleic anhydride, epoxy compound-modified polyolefins such as ethylene-glycidyl methacrylate copolymers, and ethylene-vinyl acetate copolymers Or a 2 or more types of blend thing etc. are mentioned concretely.

  In addition, aliphatic polyesters and aliphatic aromatic polyesters can be used as the sealant layer. Specific examples of the constituent material 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, Polybutylene succinate-adipate), microbial-produced polyhydroxybutyrate, polyhydroxybutyrate-valerate, polyhydroxybutyrate-hexanoate, polymers of oxyacids such as lactic acid, malic acid, glycolic acid or their co-polymers Polyester, polycaprolactone, polycaprolactone-butylene succinate, polyester having an amide bond, aliphatic polyester such as polyester having a carbonate bond, or polyethylene terephthalate-succinate having terephthalic acid, Polybutylene adipate - terephthalate, polytetramethylene adipate - terephthalate and alone or two or more of the blend of resin selected from the aliphatic-aromatic polyesters, and the like. You may add various additives (Antioxidant, a tackifier, a filler, various fillers, etc.) to these structural materials as needed.

  First, a coating solution containing a simple substance or a mixture consisting of 85% by weight or more of an isocyanate compound on a plastic substrate at a solid content ratio of 0.05 to 5 wt%, preferably 0.1 to 2 wt% is bonded. An adhesive layer is provided by coating at the coating portion of the extrusion laminate so that the thickness of the layer after drying is 1 μm or less. Thereafter, a sealant layer made of, for example, polyethylene extruded from a T-die is laminated on the adhesive layer, and immediately after that, it is passed through a heating / humidifying chamber to form a laminate composed of a plastic substrate / adhesive layer / sealant layer. The body is heated and humidified.

  The heating and humidification chamber has a temperature of 95 ° C. or higher and a humidity of 90% R.D. H. That's it. A heater and water or water vapor may be used, and the pressure may be normal pressure. Moreover, although the temperature can be raised to 100 ° C. or higher using pressurized steam, the upper temperature limit in this case is lower than the melting point of the sealant layer. About heating humidification time, what is necessary is just about 3 minutes or more, and when increasing a processing speed, heating humidification line length is lengthened as needed. In addition, after passing through the heating and humidifying chamber, it is better to provide a step of blowing off moisture adhering to the laminate with air.

Since the adhesive layer of this laminate consists of 85% by weight or more of an isocyanate compound, a urea bond is formed in a short time by reacting this isocyanate group with water at a temperature of 95 ° C. or more, and sufficient laminate strength is obtained. It expresses.

  According to the manufacturing method as described above, the initial strength between the plastic base material layer and the adhesive layer and between the adhesive layer and the sealant layer is good, and various strongly permeable contents containing volatile substances act. The laminate strength between the plastic base layer and the adhesive layer, and between the adhesive layer and the sealant layer does not decrease, and furthermore, it does not require aging for several days after laminating and produces a laminate with stable and sufficient laminate strength. It became possible to do.

  Hereinafter, specific examples of the present invention will be described.

<Example 1>
A polyethylene terephthalate film with a thickness of 12 μm with corona treatment on one side is used as a plastic substrate, and an adduct type solid content ratio of tolylene diisocyanate is 2 wt% as an adhesive layer on this corona treatment surface. After forming an adhesive layer by using, a low-density polyethylene having a thickness of 40 μm was extruded as a sealant layer by extrusion lamination at a temperature under the die of 320 ° C. and a processing speed of 20 m / min to laminate the adhesive layer and the sealant layer. Immediately after that, the film was passed through a constant temperature and humidity chamber adjusted to 95 ° C.-90% RH and subjected to heating and humidification treatment, and water droplets adhering to the surface were blown off with air to obtain a laminate according to Example 1. The thickness of the adhesive layer after drying was 0.23 μm, and the line length in the constant temperature and humidity chamber was about 60 m.

<Example 2>
A laminate according to Example 2 was obtained in the same manner as in Example 1 except that a coating liquid in which an adduct type of xylylene diisocyanate and a polyester polyol were mixed at 90:10 was used as the adhesive layer. The thickness of the adhesive layer after drying was 0.21 μm.

<Example 3>
Using a nylon film with a thickness of 15 μm with corona treatment on one side as a plastic substrate, an adduct type of hexamethylene diisocyanate and a polyether polyol are mixed as an adhesive layer in a ratio of 85:15 Example 1 except that an ethylene-methacrylic acid copolymer was used as the sealant layer and the heating and humidification treatment was performed by passing through a steam chamber adjusted to 95 ° C. to 90% RH as the heating and humidifying treatment method. Thus, a laminate according to Example 3 was obtained. The thickness of the adhesive layer after drying was 0.23 μm, the temperature under the die was 280 ° C., and the line length in the water vapor chamber was about 60 m.

  Below, the comparative example of this invention is demonstrated.

<Comparative Example 1>
The laminated body which concerns on the comparative example 1 was obtained by the method similar to Example 1 except having used the coating liquid which mixed the adduct type of xylylene diisocyanate and polyester polyol so that it might become 75:25 as an contact bonding layer. The thickness of the adhesive layer after drying was 0.22 μm.

<Comparative example 2>
Using a nylon film with a thickness of 15 μm with corona treatment on one side as a plastic substrate, using an adduct type of tolylene diisocyanate as an adhesive layer, and using an ethylene-methacrylic acid copolymer as a sealant layer, The laminated body which concerns on the comparative example 2 was obtained by the method similar to Example 1 except not having heat-humidified and not performing subsequent aging. The thickness of the adhesive layer after drying was 0.23 μm, and the temperature under the die at this time was 280 ° C.

  A pouch was prepared using each of the laminates of Examples 1 to 3 and Comparative Examples 1 and 2 obtained by the manufacturing method as described above, and a poultice (content of salicylic acid as a volatile strong penetrating substance) was prepared. Methyl and menthol) and a bath agent (containing a fragrance component as a volatile strong permeable substance) were filled and 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 (unit: N / 15 mm) between the various plastic substrates and the sealant layer of each pouch is measured. Compared with. 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. Tables 1 and 2 collectively show the results of measurement of the laminate strength before and after entering the temperature-controlled room.

表１からも明らかなように、実施例１〜３に係る積層体の各種プラスチック基材とシーラント層間における初期のラミネート強度は、シーラント切れを示すほど強固であった。また、揮発性物質を含む湿布薬や浴用剤を入れて４０℃で３ヶ月間保存したパウチにおいてもラミネート強度に変化はなく、初期のラミネート強度を十分に保っていた。

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 3 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.

  In contrast, the initial laminate strength between the plastic base material and the sealant layer of the laminate according to Comparative Example 1 was strong enough to show that the sealant was cut, but a poultice containing a volatile substance or a bath preparation was added. In the pouch stored at 3 ° C. for 3 months, the laminate strength was remarkably lowered, and it was found that the contents containing volatile substances such as poultices and bathing agents are not suitable for use as packaging materials.

  In addition, the initial laminate strength between the plastic substrate and the sealant layer of the laminate according to Comparative Example 2 did not show any laminate strength at all because it was not subjected to heat and humidification.

Claims (2)

  At least an adhesive layer and a sealant layer are provided in this order on a plastic substrate, the thickness of the adhesive layer is 1 μm or less, the adhesive layer is made of 85% by weight or more of an isocyanate compound, and the sealant layer is formed by an extrusion laminating method. A method for producing a laminated body, characterized in that after the formation and lamination, a heating and humidification treatment is performed.   The method for producing a laminate according to claim 1, wherein the isocyanate compound is a bifunctional isocyanate monomer or a derivative of a trifunctional monomer of adduct, burette, or isocyanurate type.