JP2023053621A - Laminate, coating liquid, food packaging sheet, and method for manufacturing laminate - Google Patents

Abstract

To provide a laminate which is excellent in oil resistance, water resistance, heat sealability and blocking property without using a fluorine compound even when a biomass-derived material having biodegradability is used, a coating liquid for forming a laminate, a food packaging sheet having the laminate, and a method for manufacturing a laminate.SOLUTION: A laminate has a first coating layer (A) containing modified starch on at least one paper base material, and a second coating layer (B) composed of a non-water soluble resin on the first coating layer, wherein the total of coating amounts of the first coating layer (A) and the second coating layer (B) is 0.5-10 g/m2, and air shielding property is 20 kPa or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a laminate, a coating liquid for forming the laminate, a food packaging sheet comprising the laminate, and a method for producing the laminate.

BACKGROUND ART Conventionally, a laminate sheet obtained by laminating a resin film such as polyethylene onto a base sheet such as thin paper, cardboard, or nonwoven fabric has been used as a food packaging sheet. The laminated resin film has functions such as prevention of oil stains on the base sheet due to food-derived oil and deterioration of base strength. On the other hand, in recent years, due to the worldwide trend to reduce the environmental load, the recycling of paper is accelerating. However, the lamination sheet described above is difficult to recycle paper, and the step of removing the laminated resin film layer requires expensive capital investment, which has been an obstacle to promotion of recycling. Against this background, coating liquid type food packaging sheets, which are easier to recycle, are being actively studied.
Furthermore, in recent years, it is required to further reduce the environmental load by using biomass-derived and biodegradable materials in food packaging sheets. As for the coating liquid type, the demand for biomass-derived and biodegradable materials is increasing year by year. A biomass-derived material is a material whose raw material is a biological resource. From the concept of carbon neutrality, even if incinerated, the amount of _CO2 emitted is the same as the amount absorbed _by plants as a raw material. Therefore, the environmental load is smaller than petroleum-derived products. Biodegradable materials are known to have a low environmental impact because microorganisms in the soil and ocean decompose the materials into water and carbon dioxide.
However, food packaging sheets using biomass-derived and biodegradable materials are often inferior in coating film physical properties to conventional coating liquid types. Laminates are needed. Coating film physical properties required mainly include oil resistance, water resistance, heat sealing property and blocking property.

On the other hand, in Patent Document 1, for example, a laminate having excellent oil resistance and air permeability is produced by providing a coating layer of starch containing wax on a paper substrate. Since starch is a biomass-derived material and is biodegradable, it can be said that the laminate has a low environmental impact. However, the laminate obtained by the production method of Patent Document 1 has poor water resistance because it contains only starch as a main component, and even if it contains wax, it is not sufficient to develop water resistance. Many prepared dishes and fast foods that use laminates with excellent oil resistance and air permeability contain a large amount of water in excess of the oil content, and there is a risk that the moisture will permeate the laminates. Moreover, from the viewpoint of processing the laminate, the laminate is required to have heat-sealing properties, and the composition of only starch and wax cannot exhibit the heat-sealing properties.

In Patent Document 2, a coating liquid in which starch or PVA is mixed with polylactic acid is used to create a laminate with excellent oil resistance. However, it is not sufficiently water resistant because water permeates it. In addition, mixing starch or PVA with polylactic acid deteriorates the film-forming properties, thus adversely affecting oil resistance and heat-sealing properties.

In Patent Document 3, a laminate having excellent water resistance and oil resistance is produced, which has a starch in the first layer and a fluoropolymer in the second layer. However, when the fluorine-based composition is heated, the fluorine-based compound present in the paper is thermally decomposed, generating fluorine-based hydrocarbons that are difficult to decompose in the natural world, and problems such as environmental pollution have been pointed out. In order to reduce the environmental load, it is necessary to avoid the use of substances that may have an adverse effect on the environment, while the shift from laminate film to coating liquid type is under consideration.

JP 2018-53374 A JP 2020-128616 A JP 2016-29220 A

The present invention is intended to form a laminate and a laminate that are excellent in oil resistance, water resistance, heat sealability and blocking property without using a fluorine compound even if biomass-derived and biodegradable materials are used. The purpose of the present invention is to provide a coating liquid of No. 1, a food packaging sheet comprising the laminate, and a method for producing the laminate.

The present inventors have completed the present invention as a result of earnest research in order to solve the above problems.
That is, the present invention provides a laminate having a first coating layer (A) on at least one of the paper substrates and a second coating layer (B) on the first coating layer. wherein the first coating layer (A) contains at least one modified starch (a), and the second coating layer (B) contains at least one water-insoluble resin (b) , The total coating amount of the first coating layer (A) and the second coating layer (B) is 0.5 to 10 g / m ² , and the air shielding property is 20 kPa or less. It relates to a laminate characterized by

The present invention relates to a coating liquid for forming the first coating layer (A), characterized by satisfying the following formula (1).

formula (1)
V ₂ ≤ 1.5 x V ₁
(V ₁ : Viscosity 5 seconds after applying a shear rate of 2000 (l / s) to the coating liquid, V ₂ : 5 seconds after applying a shear rate of 50 (l / s) to the coating liquid viscosity)

The present invention relates to the above coating liquid, characterized by having a solid content of 5 to 40% and a viscosity at 25° C. of 5 to 500 mPa·s as defined by JIS Z8803.

The present invention relates to the laminate having the first coating layer (A) formed from the coating liquid described above.

The present invention relates to the above laminate, wherein the water-insoluble resin (b) contains at least one of acrylic resin (c), polyester resin (d) and urethane resin (e).

In the present invention, the mass ratio ((A)/(B)) per unit area of the first coating layer (A) and the second coating layer (B) is 2/8 to 8/2. , the laminate described above.

The present invention relates to a method for producing the laminate described above, wherein the first coating layer (A) and the second coating layer (B) are formed by gravure printing or flexographic printing.

The present invention relates to the laminate described above, wherein the modified starch (a) is a modified starch obtained by hydroxyalkylating or oxidizing a starting starch.

The present invention relates to a food packaging sheet for enclosing food, comprising the laminate described above.

According to the present invention, even if a biomass-derived and biodegradable material is used, a laminate having good oil resistance, water resistance, heat sealability and blocking property without using a fluorine compound, and a laminate for forming a laminate. A coating liquid, a food packaging sheet comprising the laminate, and a method for producing the laminate can be provided.

1 is a front view of an air shielding measuring device according to the present invention; FIG. FIG. 2 is a plan view of a glass filter in the air shielding measuring device of the present invention;

The present invention will be described in detail below. It goes without saying that other embodiments are also included in the scope of the present invention as long as they match the gist of the present invention. In addition, in the present specification, the numerical range specified using "-" includes the numerical values described before and after "-" as the range of lower and upper values. Unless otherwise noted, the various components appearing in this specification may be used singly or in combination of two or more.

In addition, in this specification, when "(meth)acrylic acid" and "(meth)acrylate" are described, unless otherwise specified, "acrylic acid or methacrylic acid" and "acrylate or methacrylate" respectively. shall be represented. Further, "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer". By monomer is meant an ethylenically unsaturated double bond-containing monomer.

≪Laminate≫
The laminate of the present invention is obtained by applying a coating liquid on a paper base material and drying it to form a coating layer, and a first coating layer (A ), and further has a second coating layer (B) on the first coating layer. By forming such a laminate, resistance such as oil resistance and water resistance can be imparted to the paper substrate. The laminate of the present application can be suitably used particularly for forming a sheet for packaging food (hereinafter abbreviated as food packaging sheet). Moreover, since it is excellent in oil resistance and water resistance in addition to heat-sealing property and blocking property, it can be suitably used for applications in which the coating layer and food come into direct contact with each other.

<Paper substrate>
The paper base material is obtained by making a paper stock containing pulp, fillers, various auxiliary agents, and the like. That is, the paper support used in the present invention is not particularly limited. , white paperboard, liner, semi-glassine paper, glassine paper, one-sided glossy paper, parchment paper, and the like. Any type of paper commercially available for food packaging can be used.

<First coating layer (A)>
The first coating layer (A) comprises at least one modified starch (a). By including at least one type of modified starch (a), the coating suitability is improved, and a coating film that uniformly covers the substrate without gaps can be produced, and the second coating layer is superimposed thereon. A laminate having good oil resistance and water resistance can be obtained. Moreover, biodegradability becomes favorable by containing a modified starch (a).

(Modified starch (a))
Modified starch (a) is preferably starch modified by chemically modifying the raw material starch by some method. In the present specification, raw material starch refers to unprocessed starch, that is, starch that has been extracted from a plant and refined.
The type of starch used as a raw material is not particularly limited, and can be appropriately selected from among various known starches and used. For example, starch made from corn, potato, wheat, rice, tapioca, sweet potato, etc. can be used. Two or more of these starches can also be used in combination. Moreover, the modified starch (a) in the present invention is preferably water-soluble. Being water-soluble, it can be completely dissolved in water by applying an arbitrary temperature while stirring in water.

Methods for modifying the modified starch (a) include, for example, oxidation, urea phosphate esterification, acetate esterification, hydroxyethylation, cationization, enzyme treatment, and roasting. Modified starch (a) modified by these methods can be used alone or in combination of two or more.
Specific examples of the modified starch (a) include oxidized starch, hydrophobized starch, acetate starch, phosphoric esterified starch, acetylated starch, etherified starch, cationized starch, carbamate starch, hydroxyalkylated starch, and the like. be done. Among these, hydroxyalkylated starch and oxidized starch are preferably used from the viewpoint of stability when made into an aqueous solution.

Oxidized starch can be obtained by oxidizing starch with sodium hypochlorite. When the non-crystalline portion of the starch particles is oxidized, the molecules are depolymerized and carboxyl groups are generated, making it difficult to oxidize, making it possible to obtain oxidized starch with excellent viscosity stability and transparency. can. Since oxidized starch is chemically stable and has excellent oil resistance, it can impart excellent oil resistance to the paper substrate by applying it to the paper substrate. Cornstarch SK-20 (manufactured by Japan Cornstarch Co., Ltd.) and the like are examples of commercially available oxidized starch.

Hydroxyalkylated starch refers to modified starch (a) obtained by modifying the hydroxyl groups of raw starch with hydroxyalkyl groups. The number of carbon atoms in the hydroxyalkyl group is preferably 2-7, more preferably 2-4. The hydroxyalkyl groups contained in the hydroxyalkylated starch may contain two or more types of hydroxyalkyl groups. A hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a hydroxyhexyl group, or a combination thereof is preferred, and a hydroxypropyl group is more preferred.
Substances used for hydroxyalkylation include alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide, and etherification agents such as alkylene chlorohydrin such as ethylene chlorohydrin, with propylene oxide being particularly preferred. mentioned.
Hydroxyalkylated starch has excellent stability in an aqueous solution, and can maintain a low viscosity of the aqueous solution even at a low temperature, so that it has excellent coating suitability. Since it is possible to form a uniform coating film, excellent oil resistance can be imparted. Commercially available hydroxyalkylated starches include biostarch LV (manufactured by Nichiden Kagaku Co., Ltd.). The degree of substitution (DS) of the modified starch is preferably 0.01-1.5, more preferably 0.05-1.0. When it is 0.01 or more, the raw material starch is sufficiently modified, so that the solubility in water is improved, and the stability after dissolving in water is improved. When it is 1.0 or less, the water resistance is improved when the laminate is produced.

The modified starch (a) preferably has a weight average molecular weight of 50,000 to 300,000, more preferably 70,000 to 200,000. When the weight-average molecular weight is 50,000 or more, a tough resin coating can be obtained, and oil resistance can be improved. When the weight average molecular weight is 300,000 or less, the solution viscosity after dissolving the starch in water can be kept low. By keeping the viscosity low, the coating suitability is improved, a uniform coating film can be produced, and unevenness when the second coating layer is applied is eliminated, thereby improving the water resistance.
The weight average molecular weight is a value measured using GPC (gel permeation chromatography). Details are described in the section of Examples.

The modified starch (a) may be crosslinked with a crosslinker. By cross-linking the modified starch (a) with a cross-linking agent, the oil resistance and water resistance of the laminate can be further improved.
The cross-linking agent that can be used for modified starch (a) is not particularly limited. Examples of cross-linking agents include isocyanate-based resins, aminoaldehyde-based resins, glyoxal-based resins, epoxy-based resins, carbodiimide-based resins, inorganic metal salts, phenolic resins, melamine resins, urea resins, and epichlorohydrin-based compounds. Among these, from the viewpoint of reactivity, epichlorohydrin compounds are preferred, and polyamide epichlorohydrin resins are particularly preferred. The amount of the cross-linking agent to be added depends on the type of cross-linking agent, the number of groups for reaction, and the reaction rate, but may be about 1 to 25 parts by mass per 100 parts by mass of the solid content of the starch.

<Second coating layer (B)>
The second coating layer (B) contains at least one water-insoluble resin (b). By containing at least one kind of water-insoluble resin (b), water entering from the outside of the laminate is blocked, and the laminate has good water resistance.

(Water-insoluble resin (b))
The water-insoluble resin (b) is a resin that is not completely dissolved in water and exists in a dispersed state in water.
When the water-insoluble resin (b) is dispersed in water, the solution becomes turbid, so whether or not the resin is dispersed can be determined by measuring transmittance. Specifically, using an ultraviolet-visible-near-infrared spectrophotometer (V-770 manufactured by JASCO Corporation), the transmittance of a sample prepared so that the non-volatile content is 5% is measured. In the present invention, the water-insoluble resin (b) is defined as a resin having a transmittance of less than 80% at 660 nm when dispersed in water. A resin having a transmittance of 80% or more at 660 nm can be said to be a water-soluble resin. Even if a part of the resin is dissolved in water, it is defined as a water-insoluble resin (b) in the present invention when the above conditions are met. As for the form of the water-insoluble resin (b) in water, it may be in the form of particles dispersed in water, or it may exist in amorphous form without being completely dissolved in water. Also, the water-insoluble resin (b) used in the present invention is not particularly limited as long as it is a resin that meets the above definition. Among them, acrylic resin (c), polyester resin (d), and urethane resin (e) are preferable from the viewpoint of oil resistance and water resistance. Moreover, an organic solvent miscible with water may be contained.

[Acrylic resin (c)]
Acrylic resin (c) is a polymer of ethylenically unsaturated monomers. The ethylenically unsaturated monomer includes an ethylenically unsaturated monomer (c-1) having a linear alkyl group having 1 to 4 carbon atoms, an ethylenically unsaturated monomer having a carboxy group (c-2 ) and other ethylenically unsaturated monomers (c-3) copolymerizable with the ethylenically unsaturated monomers (c-1) and (c-2).
In the present specification, an ethylenically unsaturated monomer (c-1) having a linear alkyl group having 1 to 4 carbon atoms, an ethylenically unsaturated monomer (c-2) having a carboxy group, Other ethylenically unsaturated monomers (c-3) copolymerizable with the ethylenically unsaturated monomers (c-1) and (c-2) are added to the ethylenically unsaturated monomers (c- 1), ethylenically unsaturated monomer (c-2), and ethylenically unsaturated monomer (c-3).

The acrylic resin (c) is obtained by polymerizing an ethylenically unsaturated monomer in the presence of a chain transfer agent (X) described later to obtain a polymer having a structure represented by general formula (1) at one end. can contain. Such an acrylic resin (c) is very excellent in dispersion stability, and greatly improves the wettability and coatability of the coating liquid.

Ｒは炭素数８～１６の直鎖又は分岐アルキル基である。

R is a linear or branched alkyl group having 8 to 16 carbon atoms.

Ethylenically unsaturated monomers (c-1) having a linear alkyl group having 1 to 4 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n- Butyl (meth)acrylate is mentioned.

The ethylenically unsaturated monomer (c-1) having a linear alkyl group having 1 to 4 carbon atoms in 100% by mass of the total mass of the ethylenically unsaturated monomers may be contained in an amount of 85 to 97% by mass. Preferably, it is in the range of 90 to 96% by mass.
By containing it in the above range, the dispersion stability of the resin during synthesis is greatly improved, and a coating liquid having excellent coatability and film-forming properties can be obtained.

Examples of the ethylenic saturated monomer (c-2) having a carboxy group include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid and cinnamic acid. An ethylenic saturated monomer having a carboxyl group is used in view of the fact that an acrylic resin (c) having more excellent stability is obtained, and the coatability of the coating liquid and the coating film resistance of the coating layer to food-derived components are good. (c-2) preferably contains methacrylic acid. By containing methacrylic acid, the dispersion stability of the acrylic resin (c) is further improved, and the stability of the coating liquid is further improved.

By including the ethylenically unsaturated monomer (c-2) having a carboxy group as an ethylenically unsaturated monomer, a carboxy group can be introduced into the acrylic resin (c). From the viewpoints of improving the dispersion stability of the acrylic resin (c), rheological control during application of the coating liquid, promoting film formation, etc., it is preferable that a carboxy group is introduced into the acrylic resin (c). The acid value of the acrylic resin (c) depends on the introduction amount of the ethylenically unsaturated monomer (c-2) having a carboxy group.
The ethylenically unsaturated monomer (c-2) preferably contains 0 to 13% by mass, more preferably 0.5 to 10% by mass in 100% by mass of the total mass of the ethylenically unsaturated monomers. is in the range of By containing in the above range, the dispersion stability of the acrylic resin (c) is improved, and the coatability and film-forming properties of the coating agent are improved, thereby improving oil resistance and water resistance.
The acid value of the acrylic resin (c) is preferably in the range of 20-40 mgKOH/g, more preferably in the range of 30-40 mgKOH/g. When the acid value is 20 mgKOH/g or more, the dispersion stability of the acrylic resin (c) during synthesis is improved. A coating liquid containing the acrylic resin (c) is excellent in stability and has good coatability and film-forming properties, so that a tough and durable coating layer can be formed. Therefore, the laminate exhibits excellent oil resistance. Moreover, since the interaction between the carboxyl groups of the resin is strengthened, the heat-sealing property is also improved. On the other hand, when the acid value is 40 mgKOH/g or less, the interaction between the carboxyl groups in the coating film is also reduced, so that the blocking resistance of the laminate is improved.

Other ethylenically unsaturated monomers (c-3) are ethylenically unsaturated monomers (c-1) having a linear alkyl group having 1 to 4 carbon atoms, and ethylenically unsaturated monomers having a carboxy group. It is an ethylenically unsaturated monomer copolymerizable with (c-1) and (c-2) other than the saturated monomer (c-2).
In addition to the ethylenically unsaturated monomer (c-1) and the ethylenically unsaturated monomer (c-2), if necessary, another ethylenically unsaturated monomer (c-3) is copolymerized. By doing so, the mass average molecular weight, average particle size, etc. of the acrylic resin (c) can be controlled.

Examples of the other ethylenically unsaturated monomer (c-3) include vinylnaphthalene, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethyleneglycol (meth)acrylate, phenoxytetraethyleneglycol (meth)acrylate, Aromatic ethylenic unsaturated substances such as acrylates, phenoxyhexaethylene glycol (meth) acrylate, phenoxyhexaethylene glycol (meth) acrylate, phenyl (meth) acrylate; pentyl (meth) acrylate, heptyl (meth) acrylate, hexyl ( meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl ( C5 or more linear or branched alkyl group-containing ethylenically unsaturated monomers; alicyclic alkyl group-containing ethylenically unsaturated monomers such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; trifluoroethyl (meth)acrylate, heptadecafluoro Fluorinated alkyl group-containing ethylenically unsaturated monomers such as decyl (meth)acrylate; sodium 2-acrylamide 2-methylpropanesulfonate, methallylsulfonic acid, methallylsulfonic acid, sodium methallylsulfonate, allylsulfonic acid , sodium allylsulfonate, ammonium allylsulfonate, sulfo group-containing ethylenically unsaturated monomers such as vinylsulfonic acid; (meth)acrylamide, N-methoxymethyl-(meth)acrylamide, N-ethoxymethyl-(meth) acrylamide, N-propoxymethyl-(meth)acrylamide, N-butoxymethyl-(meth)acrylamide, N-pentoxymethyl-(meth)acrylamide, N,N-di(methoxymethyl)acrylamide, N-ethoxymethyl-N -methoxymethylmethacrylamide, N,N-di(ethoxymethyl)acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N,N-di(propoxymethyl)acrylamide, N-butoxymethyl-N-(propoxymethyl ) methacrylamide, N,N-di(butoxymethyl)acrylamide, N-butoxymethyl-N-(methoxymethyl)methacrylamide, N,N-di(pentoxymethyl)acrylamide, N-methoxymethyl-N-(pen Amido group-containing ethylenically unsaturated monomers such as methacrylamide, N,N-dimethylaminopropylacrylamide, N,N-diethylaminopropylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide and diacetoneacrylamide. Polymer; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol mono (meth)acrylate, 4-hydroxyvinylbenzene, 1-ethynyl-1-cyclo hydroxyl group-containing ethylenically unsaturated monomers such as hexanol and allyl alcohol; polyoxyethylene group-containing ethylenically unsaturated monomers such as methoxypolyethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; ) acrylate, diethylaminoethyl (meth)acrylate, methylethylaminoethyl (meth)acrylate, dimethylaminostyrene, diethylaminostyrene and the like, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methylethylaminoethyl ( Amino group-containing ethylenically unsaturated monomers such as meth)acrylate; epoxy group-containing ethylenically unsaturated monomers such as glycidyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate; diacetone (meth)acrylamide , ketone group-containing ethylenically unsaturated monomers such as acetoacetoxy (meth) acrylate; allyl (meth) acrylate, 1-methylallyl (meth) acrylate, 2-methylallyl (meth) acrylate, 1-butenyl (meth) acrylate, 2-butenyl (meth)acrylate, 3-butenyl (meth)acrylate, 1,3-methyl-3-butenyl (meth)acrylate, 2-chloroallyl (meth)acrylate, 3-chloroallyl (meth)acrylate, o-allylphenyl (meth) acrylate, 2-(allyloxy) ethyl (meth) acrylate, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, geranyl (meth) acrylate, rhodinyl (meth) acrylate, cinnamyl (meth) acrylate, diallyl maleate, Diallyl itaconic acid, vinyl (meth) acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, 2-(2'-vinyloxyethoxy) ethyl (meth) acrylate, ethylene glycol di(meth) acrylate, triethylene glycol ( meth)acrylate, tetraethylene glycol (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, 1,1,1-trishydroxymethylethane diacrylate, 1,1,1-trishydroxy Ethylene having two or more ethylenically unsaturated groups such as methylethane triacrylate, 1,1,1-trishydroxymethylpropane triacrylate, divinylbenzene, divinyl adipate, diallyl isophthalate, diallyl phthalate, and diallyl maleate γ-Methacryloxypropyltrimethoxysilane, γ-Methacryloxypropyltriethoxysilane, γ-Methacryloxypropyltributoxysilane, γ-Methacryloxypropylmethyldimethoxysilane, γ-Methacryloxypropylmethyldimethoxysilane ethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxysilane, vinyl trimethoxysilane Alkoxysilyl group-containing ethylenically unsaturated monomers such as methoxysilane, vinyltriethoxysilane, vinyltributoxysilane, and vinylmethyldimethoxysilane; N-methylol(meth)acrylamide, N,N-dimethylol(meth)acrylamide, alkyl methylol group-containing ethylenically unsaturated monomers such as etherified N-methylol (meth)acrylamide; but not limited thereto.

Styrenes such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, and m-methylstyrene may also be used as long as they do not interfere with the effect, but they are not included in terms of environmental friendliness. is preferred.

Among the other ethylenically unsaturated monomers (c-3) exemplified above, from the viewpoint of improving the stability of the acrylic resin (c) and improving the physical properties of the coating liquid by increasing the molecular weight, other ethylenically unsaturated monomers (c-3) is more preferably acrylamide, glycidyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, or N-methylolacrylamide.

The content of other ethylenically unsaturated monomers (c-3) is preferably 0 to 10% based on 100% by mass of the total ethylenically unsaturated monomers. When the content is 10% or less, the dispersion stability of the synthesized acrylic resin (c) is improved, so that a coating liquid having excellent coatability and film-forming properties can be obtained, and as a result, oil resistance is improved. - A laminate with excellent water resistance can be produced.

The method of polymerizing the acrylic resin (c) is not particularly limited, but emulsion polymerization is preferably used from the viewpoint that a resin dispersion having a high molecular weight, low viscosity and high solid content can be easily obtained in an aqueous medium. The acrylic resin (c) synthesized using emulsion polymerization may have only one glass transition temperature, or may have two or more different glass transition temperatures. As a method for preparing an acrylic resin (c) having different glass transition temperatures (hereinafter referred to as Tg), during emulsion polymerization, the dropping tank is divided into multiple stages, and ethylenically unsaturated The acrylic resin (c) is synthesized in advance by multi-stage polymerization in which the monomer composition is changed and dropped, or by bulk polymerization or solution polymerization, and after dissolving or dispersing it in an aqueous phase, the acrylic resin (c) is added. There is a method of polymerizing by dropping an ethylenic monomer so that a polymer having a different Tg is produced, but the process is not complicated and the resulting acrylic resin (c) has good dispersion stability. Considering these points, the acrylic resin (c) having two or more different glass transition points is more preferably synthesized by multistage polymerization. The glass transition temperature Tg is preferably 0 to 100°C, more preferably 15 to 80°C. If there are two or more Tgs, their average value is adopted. The average particle size is preferably in the range of 30-300 nm. When the particle size is within the above range, heat-sealing properties and oil resistance can be sufficiently exhibited. The weight average molecular weight is preferably 100,000 or more. When the weight-average molecular weight is 100,000 or more, the coat layer forms a tough coating film, so that a laminate that does not permeate even when exposed to moisture or oil can be obtained.
The glass transition temperature of the acrylic resin can be determined by performing differential scanning calorimetry (DSC measurement) on a solid obtained by drying the resin. Details are described in the section of Examples.

As the radical polymerization initiator used in the polymerization reaction of the ethylenically unsaturated monomers, known oil-soluble polymerization initiators and water-soluble polymerization initiators can be used. Well, you may mix and use 2 or more types. The radical polymerization initiator is preferably used in an amount of 0.1 to 4 parts by mass, more preferably 0.2 to 2 parts by mass based on 100 parts by mass of the total ethylenically unsaturated monomers.

The oil-soluble polymerization initiator is not particularly limited. Organic peroxides such as oxy-3,5,5-trimethylhexanoate and di-tert-butyl peroxide; 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4- azobis compounds such as dimethylvaleronitrile, 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobis-cyclohexane-1-carbonitrile;

In emulsion polymerization, it is preferable to use a water-soluble polymerization initiator. Examples of water-soluble polymerization initiators include ammonium persulfate (APS), potassium persulfate (KPS), hydrogen peroxide, 2,2′-azobis ( Conventionally known compounds such as 2-methylpropionamidine) dihydrochloride can be preferably used.

In emulsion polymerization, a reducing agent may be used together with the polymerization initiator. By using a reducing agent together, the speed of emulsion polymerization can be accelerated and emulsion polymerization at low temperatures can be facilitated. Reducing agents include, for example, ascorbic acid, ersorbic acid, tartaric acid, citric acid, glucose, reducing organic compounds such as metal salts such as formaldehyde sulfoxylate; sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium metabisulfite reducing inorganic compounds such as; ferrous chloride, Rongalite, and thiourea dioxide.
It is preferable to use 0.05 to 5 parts by mass of these reducing agents based on 100 parts by mass of the total amount of ethylenically unsaturated monomers.

The polymerization temperature may be equal to or higher than the polymerization initiation temperature of the polymerization initiator. For example, in the case of a peroxide polymerization initiator, it is usually about 80°C. Although the polymerization time is not particularly limited, it is usually 2 to 24 hours. The ethylenically unsaturated monomer may be polymerized by photochemical reaction or radiation irradiation without using the polymerization initiator described above.

In the polymerization of the ethylenically unsaturated monomer, if necessary, a buffer or chain transfer agent may be used. Buffers include, for example, sodium acetate, sodium citrate, sodium bicarbonate. Chain transfer agents are, for example, n-hexylmercaptan, n-heptylmercaptan, t-hexylmercaptan, t-heptylmercaptan, n-octylmercaptan, t-octylmercaptan, n-nonylmercaptan, t-nonylmercaptan, n-decyl Mercaptan, t-decylmercaptan, n-undecylmercaptan, t-undecylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, n-tridecylmercaptan, t-tridecylmercaptan, n-tetradecylmercaptan, t-tetra Decylmercaptan, n-heptadecylmercaptan, t-heptadecylmercaptan, t-hexadecylmercaptan, n-hexadecylmercaptan, n-heptadecylmercaptan, n-octadecylmercaptan, t-heptadecylmercaptan, t-octadecyl Mercaptan, 2-ethylhexyl mercaptomercaptoacetate, octyl mercaptoacetate, methoxybutyl mercaptopropionate, 2-ethylhexyl mercaptopropionate, octyl mercaptopropionate, stearyl mercaptopropionate and the like. The buffer material is preferably used in the range of 0 to 1 part by mass, more preferably 0.05 to 0.5 parts by mass, based on the total amount of ethylenically unsaturated monomers of 100 parts by mass. . Further, the chain transfer agent is preferably used in the range of 0.4 to 3 parts by mass, more preferably 0.6 to 2 parts by mass based on 100 parts by mass of the total amount of ethylenically unsaturated monomers. Range.

Among the above chain transfer agents, it is preferable to use the chain transfer agent (X), which is a chain transfer agent represented by the following general formula (2).

Ｒは炭素数８～１６の直鎖又は分岐アルキル基である。

R is a linear or branched alkyl group having 8 to 16 carbon atoms.

By using the chain transfer agent (X) at the time of polymerization, the structure represented by the general formula (1) can be introduced to one end of the polymer of ethylenically unsaturated monomers. A polymer having a structure represented by general formula (1) at one end has a moderate polarity with a terminal alkyl group R, which is a low polar site, and a highly polar acrylic resin (c) bonded thereto. Contrast is produced, so surface activity is exhibited, and the dispersion stability of the acrylic resin (c) is further improved. Therefore, the stability of the coating liquid is also improved, and the formation of precipitates and aggregates that lead to poor coating and poor film formation is greatly reduced. It also has the effect of improving the wettability of the resin to the substrate. As a result, the coating liquid firmly penetrates into the base material and binds, so that the binding at the interface between the base material and the resin becomes stronger.

Chain transfer agents (X) include, for example, n-octylmercaptan, t-octylmercaptan, n-nonylmercaptan, t-nonylmercaptan, n-decylmercaptan, t-decylmercaptan, n-undecylmercaptan, t-un decylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan, n-tridecylmercaptan, t-tridecylmercaptan, n-tetradecylmercaptan, t-tetradecylmercaptan, n-heptadecylmercaptan, t-heptadecylmercaptan, t-hexadecylmercaptan, n-hexadecylmercaptan and the like.

A basic compound may be used as a neutralizing agent in order to improve the dispersion stability of the acrylic resin (c) during the polymerization of the ethylenically unsaturated monomer. Basic compounds include, for example, aqueous ammonia, various organic amines such as dimethylaminoethanol, diethanolamine and triethanolamine; inorganic alkaline agents such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide; is mentioned. The basic compound may be added after the first dropwise addition is completed, or after the reaction is completed.

Further, when obtaining the acrylic resin (c), a surfactant is used for the purpose of improving the dispersion stability of the acrylic resin (c) as long as it does not adversely affect the physical properties of the coating liquid and the food packaging sheet. can do. Examples of surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. Alternatively, it is preferably a nonionic surfactant. Surfactants can be used alone or in combination of two or more.

Examples of usable anionic surfactants include higher fatty acid salts such as sodium oleate, alkylarylsulfonates such as dodecylbenzenesulfonic acid, alkylsulfuric acid ester salts such as sodium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate. polyoxyethylene alkyl ether sulfate salts, sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, alkyl sulfosuccinate salts and derivatives thereof such as sodium polyoxyethylene lauryl sulfosuccinate, polyoxyethylene distyrenated phenyl ether sulfate salts etc. Among the above, the surfactant is preferably an alkyl sulfate salt or an alkyl sulfosuccinate salt, more preferably the alkyl sulfate salt is lauryl sulfate, and the alkyl sulfosuccinate salt is dioctyl sulfosuccinate. preferable.

Nonionic surfactants include, for example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; Sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monostearate and sorbitan trioleate, polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate, polyoxyethylene monolaurate polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate, glycerol higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride, polyoxyethylene/polyoxypropylene block copolymers, polyvinyl alcohol, polyvinylpyrrolidone, polyoxyethylene Ethylene distyrenated phenyl ether etc. are mentioned.

As the surfactant, a polymerizable surfactant having one or more radically polymerizable ethylenically unsaturated double bonds in the molecule can be used.

The polymerizable surfactant is preferably a polymerizable anionic surfactant or a polymerizable nonionic surfactant.

Examples of the polymerizable anionic surfactant include sulfosuccinic acid esters, alkyl ethers, alkylphenyl ethers, alkylphenyl esters, (meth)acrylate sulfate esters, and phosphate esters as main skeletons.
Examples of the polymerizable nonionic surfactant include alkyl ethers, alkylphenyl ethers, alkylphenyl esters, and the like as the main skeleton.

[Polyester resin (d)]
Any polyester resin (d) can be obtained by polycondensing one or more polybasic acid components and one or more polyhydric alcohol components, depolymerizing with polybasic acid components after polycondensation, or polycondensing It can be produced by a known method such as subsequent addition of an acid anhydride. Polyester resin (d) also includes polylactic acid-based resins produced by using lactic acid or caprolactone alone or both.

Specific examples of the polybasic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid and biphenyldicarboxylic acid, oxalic acid, succinic acid, succinic anhydride, and adipine. acids such as azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated dimer acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid,
Saturated or unsaturated aliphatic dicarboxylic acids such as itaconic anhydride, citraconic acid, citraconic anhydride, and dimer acid, unsaturated dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, terpene-maleic acid adducts, and acid anhydrides thereof , 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, 2,5-norbornenedicarboxylic anhydride, tetrahydrophthalic acid, alicyclic dicarboxylic acids such as tetrahydrophthalic anhydride, etc. is mentioned. Also, a small amount of 5-sodiumsulfoisophthalic acid or 5-hydroxyisophthalic acid can be used as necessary.

Tri- or higher functional polybasic acids can also be used, such as trimellitic acid, pyromellitic acid,
Benzophenonetetracarboxylic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), 1,2,3,4-butanetetracarboxylic acid, and the like may also be included.

Further, as the polybasic acid, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3' ,4,4′-diphenyltetracarboxylic dianhydride (BPDA), ethylene glycol bisanhydrotrimellitate (TMEG), 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA) , 4,4′-(Hexafluoroisopropylidene)diphthalic dianhydride (6FDA), 2,2′-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA), glycerin trisanhydrotrimellitate Acid dianhydrides such as can also be used.

Examples of polyhydric alcohol components include aliphatic glycols, alicyclic glycols, ether bond-containing glycols, and the like. Specific examples of aliphatic glycols include
For example, ethylene glycol, 1,2-propanediol, 1,3-propanediol,
1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9 -nonanediol, 2-ethyl-2-butylpropanediol, and the like. Specific examples of alicyclic glycols include 1,4-cyclohexanedimethanol. Specific examples of ether bond-containing glycols include diethylene glycol, triethylene glycol, dipropylene glycol, and bisphenols (bisphenol A) such as 2,2-bis[4-(hydroxyethoxy)phenyl]propane. Examples include ethylene oxide adducts, ethylene oxide adducts of bisphenols (bisphenol S) such as bis[4-(hydroxyethoxy)phenyl]sulfone, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like. Among these, long-chain ether bond-containing glycols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like having a molecular weight of 500 or more.

Tri- or higher functional polyhydric alcohols may include, for example, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, polyglycerin, xylitol, sorbitol, glucose, fructose, mannose, and the like. Moreover, you may modify|denature and use a part of polyhydric-alcohol component mentioned above.

The polyester resin (d) may optionally contain fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and ester-forming derivatives thereof, benzoic acid, p-tert- monocarboxylic acids such as butylbenzoic acid, cyclohexanoic acid, and 4-hydroxyphenylstearic acid; monoalcohols such as stearyl alcohol and 2-phenoxyethanol; and hydroxycarboxylic acids such as ε-caprolactone, lactic acid, β-hydroxybutyric acid, and p-hydroxybenzoic acid. An acid or an ester-forming derivative thereof may be copolymerized.

A polylactic acid-based polyester can be easily obtained by ring-opening addition polymerization of lactides and lactones using a polyol as an initiator. The polyol may be the above-described polyhydric alcohol, or may be a polyester polyol having an ester bond. As lactides, lactide (cyclic dimer of lactic acid), glycolide (cyclic dimer of glycolic acid), and the like can be used. As lactones, for example, β-propionolactone, β-butyrolactone, pivalolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone and the like can be used. Moreover, these compounds do not necessarily need to be used alone, and a plurality of types can be copolymerized. Among them, ε-caprolactone and lactide, which are excellent in biodegradability and easy to polymerize, are preferably used.

When polymerizing the polyester resin (d), it is effective to add various antioxidants. When the polymerization temperature is high or the polymerization time is long, the polylactic acid segment may undergo oxidative deterioration due to its low heat resistance, resulting in coloration. In addition, if a segment having low heat resistance such as polyether is copolymerized, it may become more susceptible to oxidative deterioration. In this case, addition of an antioxidant is particularly effective. Examples of antioxidants include known antioxidants such as phenol antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, nitro compound antioxidants, and inorganic compound antioxidants. .

By introducing acid groups such as carboxyl groups into the resin skeleton of the polyester resin (d), all or part of the acid groups can be neutralized with a basic compound to form an aqueous dispersion. is.
As a method for introducing a carboxy group, a method of adjusting the amount of polybasic acid so that the terminal of the polyester resin becomes a carboxy group and introducing it, or a polybasic acid with a functionality of 3 or more is used to add a carboxy group to the polymer side chain. can be introduced. Also, by introducing a sulfonate as a functional group, it is possible to form an aqueous dispersion in water. A method of introducing the sulfonate includes a method of using a sulfonic acid group-containing polybasic acid such as 5-sodiumsulfoisophthalic acid.

Basic compounds used for neutralizing the acid groups introduced into the polyester resin (d) include ammonia, organic amine compounds, inorganic basic compounds and the like.

Specific examples of the organic amine compound include alkylamines such as triethylamine, isopropylamine, ethylamine, diethylamine and sec-butylamine, 3-ethoxypropylamine, propylamine, N,N-dimethylethanolamine and 3-methoxypropyl. Alkoxyamines such as amines, Alkanolamines such as N,N-diethylethanolamine, aminoethanolamine, N-methyl-N,N-diethanolamine, monoethanolamine, diethanolamine and triethanolamine, morpholine, N-methylmorpholine , and N-ethylmorpholine.

Specific examples of the inorganic basic compound include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium hydrogen carbonate and sodium carbonate, hydrogen carbonates, and ammonium carbonate and the like can be used. A basic compound of a polyvalent metal forms a sparingly soluble salt in water with multiple carboxy groups contained in the polyester resin (d), and may deteriorate the dispersibility. It is preferable that the neutralization rate for is 50% or less.

[Urethane resin (e)]
Urethane resin (e) is a reaction product of polyol and polyisocyanate.
Examples of polyols that can be used for synthesizing the urethane resin (e) include polyether polyols such as polyethylene glycol, polypropylene glycol, poly(ethylene/propylene) glycol, and polytetramethylene glycol; ethylene glycol, propylene glycol, dipropylene glycol, Diethylene glycol, triethylene glycol, butylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3′-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,3- butanediol, 1,4-butanediol, neopentyl glycol, octanediol, butylethylpentanediol, 2-ethyl-1,3-hexanediol, cyclohexanediol, bifunctional diols such as bisphenol A, and/or glycerin, trifunctional diols such as trimethylolpropane and pentaerythritol; dibasic acids such as terephthalic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, hydrogenated dimer acid, phthalic anhydride, isophthalic acid and trimellitic acid; Polyester polyol obtained by reacting; Polycarbonate polyol obtained by reacting the above-mentioned difunctional diol with dialkyl carbonate, alkylene carbonate, or diaryl carbonate; Hydroxyl group-containing polybutadiene, acid group-containing hydrogenated polybutadiene, hydroxyl group-containing polyisoprene, Polyolefin polyols such as hydroxyl-containing hydrogenated polyisoprene, hydroxyl-containing chlorinated polypropylene, and hydroxyl-containing chlorinated polyethylene; castor oil polyols made from plant-derived oils;
Furthermore, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 2-methyl -1,3-propylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol , 2-ethyl-1,3-hexanediol, 2,2-dimethyl-3-hydroxypropyl-2′,2′-dimethyl-3′-hydroxypropanoate, 2-n-butyl-2-ethyl-1, 3-propanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol Aliphatic diols such as 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxyethyl)cyclohexane, 1,4-bis(hydroxypropyl)cyclohexane , 1,4-bis(hydroxymethoxy)cyclohexane, 1,4-bis(hydroxyethoxy)cyclohexane, 2,2-bis(4-hydroxymethoxycyclohexyl)propane, 2,2-bis(4-hydroxyethoxycyclohexyl)propane , bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, 3(4),8(9)-tricyclo[5.2.1.0]decanedimethanol, etc. one or more polyols selected from aromatic glycols such as aromatic glycols such as ethylene oxide or propylene oxide adducts to both terminal hydroxyl groups of bisphenol A, and a dibasic acid having a sulfonic acid metal base 5- A polyester polyol obtained by condensing sodium sulfoisophthalic acid, 3-sodium sulfoterephthalic acid and 4-potassium sulfo-1,8-naphthalenedicarboxylic anhydride may also be used. It is also possible to use a polyol (polylactic acid diol) having a hydroxyl group at the end of the polylactic acid-based polyester described above, and a urethane resin (e) containing a polylactic acid moiety can be obtained.

Examples of polyisocyanates that can be used to synthesize the urethane resin (e) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, and 4,4′-diphenylmethane diisocyanate. , xylylene diisocyanate, lysine diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisocyanate, 3,3′-dimethoxy-4,4′-biphenylene diisocyanate, 3,3′-dichloro-4,4′- aromatic polyisocyanates such as biphenylene diisocyanate, 1,5-naphthalene diisocyanate and 1,5-tetrahydronaphthalene diisocyanate; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; isophorone diisocyanate, 1, alicyclic polyisocyanates such as 4-cyclohexylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate;

In synthesizing the urethane resin (e), a low-molecular-weight diol may be used in combination for the purpose of adjusting the urethane bond concentration and introducing various functional groups.
The low-molecular-weight diol is preferably a diol having a molecular weight of 500 or less. 4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butylenediol, dipropylene glycol, glycerin, trimethylolpropane, Trimethylolethane, 1,2,6-butanetriol, pentaerythritol, sorbitol, N,N-bis(2-hydroxypropyl)aniline, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, 2,2-dimethylolbutyric acid , 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dihydroxypropionic acid and dihydroxybenzoic acid.

Moreover, the urethane resin (e) may be terminal-modified or chain-extended.
Examples of compounds that can be used for terminal modification and chain extension reactions include hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and its derivatives, phenylenediamine, tolylenediamine, and xylene. diamines such as diamine and N-(β-aminoethyl)ethanolamine; dihydrazides such as adipic acid dihydrazide and isophthalic acid dihydrazide;

A chain transfer agent may be used for molecular weight adjustment and terminal modification in synthesis of the urethane resin (e). A compound having a sulfanyl group is preferably used as the chain transfer agent, such as 2-hydroxyethanethiol, 3-hydroxypropyl-1-thiol, 1-hydroxypropyl-2-thiol, 4-hydroxy-1-butane. Hydroxyalkanethiols such as thiols; dithiols such as 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 2-amino Aminoalkanethiols such as ethanethiol, 3-aminopropyl-1-thiol, 1-aminopropyl-2-thiol, 4-amino-1-butanethiol; 2-aminothiophenol, 3-aminothiophenol, 4- aminobenzenethiols such as aminothiophenol; As for the urethane resin (e) whose terminal is modified with a sulfanyl group, an acrylic-modified urethane resin can be synthesized by using the ethylenically unsaturated monomer and the polymerization initiator described above. An acrylic-modified urethane resin can be suitably used as one type of urethane resin (e).

Commercially available products may be used as the aqueous dispersion of the urethane resin (e), and examples of such commercial products include Superflex series (SF-170, SF-210, etc.) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Ucoat manufactured by Sanyo Kasei Co., Ltd. , Permaline series (UX-310, UX-3945, etc.), Arakawa Chemical Juliano series (W-600, W-321, etc.), ADEKA Adekapon Titer series (HUX-420A, HUX-386), Ube Industries Examples include UW series (UW-5002, UW-5020, etc.) and Taisei Fine Chemicals Acryt series (WBR2000U, WBR2101, WEM-200U, etc.).

<Coating amount in laminate>
The total coating amount of the first coating layer (A) and the second coating layer (B) in the laminate is 0.5 to 10 g/m ² and 1.5 to 4 g/m ² is more preferable. When the total coating amount is 0.5 g/m ² or more, the coating layer is sufficient to cover the paper base material, preventing uneven coating and improving oil resistance, water resistance and heat sealability. becomes good. When the total coating amount is 10 g/m ² or less, it becomes possible to prevent blocking that occurs when the coated surface and the non-coated surface are overlapped. The coating amount of each of the first coating layer (A) and the second coating layer (B) as a single unit is preferably 0.1 to 8 g/m ² , more preferably 0.3 to 3.2 g/m2. More preferably ^m2 . By being included in this range, a smooth and even film can be formed on the paper substrate, and a laminate having good oil resistance, water resistance and blocking property can be obtained.

In the laminate, the mass ratio ((A)/(B)) per unit area of the first coating layer (A) and the second coating layer (B) is 2/8 to 8/ 2 is preferred, and 4/6 to 6/4 is more preferred.
The first coating layer (A) is water-soluble and has low resistance to water but high resistance to oil. The second coating layer (B) is a water-insoluble resin (b) and has high resistance to water but low resistance to oil. When the mass ratio per unit area is within this range, a laminate that satisfies both oil resistance and water resistance can be obtained.

<Air shielding>
The air shielding property in the present application is the value of the degree of pressure reduction measured under the condition that the degree of pressure reduction is 70 kPa when copy paper is placed in the opening using a pressure reduction device. Specifically, using a decompression device, the degree of decompression is 70 kPa when copy paper (manufactured by ASKUL Corporation, product name: Multi Paper Super White +) is placed in an opening with a diameter of 4 cm and an area of 12.56 cm ^{2 .} Under the conditions in which the hydraulic pump is set as described above, the laminate can be placed in the opening for measurement. A smaller value means a higher degree of sealing, meaning that the film is formed on the paper substrate without gaps.

The laminate of the present invention has an air shielding property of 20 kPa or less. More preferably, the air shielding property is 5 kPa or less. A laminate having an air shielding property of 20 kPa or less forms a uniform coating film with little unevenness on the paper substrate, thereby improving oil resistance and water resistance.

Air shielding properties are measured using the apparatus shown in FIG. A glass filter 2 is installed on the top of a glass container 1, a rubber tube 3 is provided on the side of the glass container, and a hydraulic pump 4 and a vacuum gauge 5 are connected. A hydraulic pump 4 is used to reduce the pressure, and a vacuum gauge 5 is used to measure the degree of pressure reduction at that time. Only the filter part 6 at the top of the device is air-permeable, and the other parts are completely sealed. The filter portion 6 has a circular shape with a diameter of 4 cm, and the glass filter portion is flat with respect to the glass portion around the glass filter, neither protruding nor recessing. If the glass filter portion is not flat, an accurate decompression degree cannot be measured when the laminate is installed. Laminated body 7 is placed so that the coated surface faces downward with respect to the glass filter portion, the degree of pressure reduction is measured, and the obtained value is defined as air shielding property.

<Coating liquid>
A coating liquid used for producing a laminate will be described. A coating liquid for forming the first coating layer is prepared using the modified starch (a) and the water-insoluble resin (b). Each coating liquid can be prepared by mixing the modified starch (a) and the water-insoluble resin (b) with water or a hydrophilic organic solvent in an arbitrary ratio. It is also possible to use it alone without mixing it with water or a hydrophilic organic solvent. The modified starch (a) and the water-insoluble resin (b) used at that time may be used alone, or two or more of them may be used in combination. Moreover, additives such as extender pigments, antifoaming agents, leveling agents, preservatives, solvents, and waxes can be included as optional components. It is preferable that the optional component, if left in the laminate after coating, does not adversely affect health.

Examples of hydrophilic solvents include monohydric alcohol solvents such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol and 2-methyl-2-propanol; ethylene; glycol, 1,3-propanediol, propylene glycol, 1,2-butanediol, 1,4-butanediol, pentylene glycol, 1,2-hexanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, Glycol-based solvents such as tetraethylene glycol; ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, triethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, Glycol ether solvents such as diethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether; Lactam solvents such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, ε-caprolactam; formamide, N-methylformamide, N,N-dimethylformamide, Idemitsu Equamid M-100 , and amide solvents such as Equamid B-100. These can be used singly or in combination of two or more.

As the extender pigment, those approved as foods or food additives are preferably used. Specific examples include talc, silica, calcium carbonate, barium sulfate, titanium oxide, diatomaceous earth (white carbon), and cellulose powder.

Solvents include ethanol, isopropyl alcohol, propylene glycol, glycerin and the like from the viewpoint of oral safety.

Waxes include, for example, carnauba wax, beeswax, paraffin wax, modified paraffin wax, polyethylene wax, oxidized polyethylene wax, modified polyethylene wax, polypropylene wax, oxidized polypropylene wax, modified polypropylene wax, ethylene vinyl acetate copolymer wax, modified ethylene vinyl acetate copolymer wax. Polymerized waxes, fatty acid amides, microcrystalline waxes, Fischer-Tropsch waxes, polytetrafluoroethylene and the like.

The coating liquid for producing the first coating layer (A) has a solid content of 5 to 40% and a viscosity at 25° C. specified in JIS Z8803 of 5 to 500 mPa s. preferable. When the viscosity and solid content are within this range, it is possible to form a uniform coating film on the substrate, and the oil resistance, water resistance and heat sealability are improved. More preferably, the solid content is 15% to 35%, and the viscosity at 25°C defined by JIS Z8803 is 30 to 300 mPa·s.
The viscosity of the coating liquid is a value measured using a Brookfield viscometer at a temperature of 25°C. Details are described in the section of Examples.

The coating liquid for forming the first coating layer (A) preferably has viscosities V ₁ and V ₂ measured using a rheometer that satisfy the conditions shown in formula (1).
formula (1)
V ₂ ≤ 1.5 x V ₁
(V ₁ : Viscosity 5 seconds after giving a share at a shear rate of 2000 (l / s), V ₂ : Viscosity 5 seconds after giving a share at a shear rate of 50 (l / s))
When the coating liquid for forming the first coating layer (A) satisfies the condition shown in formula (1), it is possible to reduce the thixotropic properties of the coating liquid.

It is known that the surface of a paper base material is not completely uniform and has some unevenness, although the degree varies depending on the presence or absence of surface treatment. In the present invention, it is important to apply the coating film of the first layer on the paper substrate as tightly as possible. When the thixotropic property increases, in gravure and flexo printing, the fluidity of the coating fluid is good when the force is applied at the moment of transfer from the plate to the substrate, but the transfer onto the paper substrate Viscosity increases as soon as it is applied. As a result, the wetting and spreading on the paper substrate is deteriorated, and a coating film cannot be formed on the paper substrate without gaps. If there is an uncoated surface on the paper substrate, water and oil will enter from that surface, resulting in poor water resistance and oil resistance of the laminate. However, when the viscosity condition is a viscosity that satisfies the above formula (1), the thixotropic property is lowered, and the paper substrate can be covered without gaps. Then, the water-resistant resin (b), which has excellent water resistance, is applied as the second layer coating film on the first layer coating film that has been coated on the paper substrate without any gaps. , a laminate having both oil resistance and heat sealability can be obtained.

<Method for manufacturing laminate>
A first coating layer (A) and a second coating layer (B) are coated in this order on at least one side of a paper substrate to form a laminate. Another layer may be provided on the second coating layer. The number of times of coating when producing the first coating layer (A) and the second coating layer (B) is not particularly limited, and each may be produced by coating at once, or may be coated repeatedly. It can also be produced by

As a coating method for producing a laminate, known coating methods such as offset gravure coater, gravure coater, doctor coater, bar coater, blade coater, flexo coater and roll coater can be used. A gravure method is preferred. The flexographic method is a method in which a coating liquid is first transferred from an intaglio called an anilox roll onto a resin or rubber plate, and the coating liquid on the resin or rubber plate is transferred to the original roll. It is also possible to pattern a resin plate or a rubber plate. The gravure method includes a method in which the coating liquid is directly transferred from the intaglio to the original sheet, and a so-called gravure offset method in which the coating liquid is first transferred from the intaglio to the planographic plate and then transferred to the original sheet. It is also possible to pattern an intaglio. In the case of the gravure method, it is preferable to perform press treatment with a smoothing roll after coating.
To obtain a laminate having good oil resistance, water resistance and heat sealability, capable of forming a smooth and even coating film even when the coating amount is small by using a flexographic method or a gravure method. can be done.

<Food packaging sheet>
The laminate of the present invention can be used as a food packaging sheet in applications where the laminate comes into direct contact with food. When used as a food packaging sheet, it is desirable that it is composed only of substances that comply with the regulations of each country.

By applying the coating liquid several times after forming the coating layer, the water resistance, oil resistance and heat sealability can be improved. In addition, the coating layer may be impregnated into the substrate sheet, or a non-impregnated embodiment can also be used.

Food packaging sheets are used not only for confectionery such as popcorn, chocolate, and caramel, but also for fruits and vegetables such as vegetables and fruits, as well as burgers such as hamburgers, hot dogs, hamburgers, and rice burgers, fried chicken, French fries, fried chicken, and tempura. , Fried foods such as fried bread, grilled chicken, yakitori, grilled meat and seafood such as saury, meat buns, sweet bean buns, dumplings, shumai, spring rolls and other foods. It can also be used for foods containing multiple ingredients such as amino acids and ketchup, sauces, and sauces with a high water content. It can also be used as a sheet for packaging various foods, such as paper trays for frozen foods and lunch boxes, and can also be used for heating in a microwave oven after being wrapped. The food packaging sheet of the present invention is preferably used for applications in which the coating layer is in direct contact with various foods as described above.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the examples below do not limit the scope of the present invention. In the examples, "part" means "mass part" and "%" means "mass %". Numerical values in the table are the mass of the solid content, and blanks indicate that they are not used.
The methods for measuring the glass transition temperature, acid value, average particle size, and weight average molecular weight of the resin are as follows.

<Glass transition temperature>
The glass transition temperature of the resin was measured using a DSC (Differential Scanning Calorimeter, manufactured by TA Instruments). Specifically, an aluminum pan in which about 3 mg of dried resin was precisely weighed and an empty aluminum pan as a reference were set in a DSC measurement holder, and the temperature was increased at 10 ° C./min. The temperature at the intersection of the baseline on the low temperature side of the endothermic phenomenon in the obtained DSC curve and the tangent line at the point of inflection was defined as the glass transition temperature (Tg).

<Acid value>
The acid value of the resin is the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of the dried resin. The dried water-soluble resin was subjected to potentiometric titration with a potassium hydroxide/ethanol solution according to the method described in JIS K2501.

<Average particle size>
The average particle size is obtained by diluting an aqueous resin dispersion 500 times with water, and measuring about 5 ml of the diluted solution by a dynamic light scattering measurement method (measurement device manufactured by Nanotrac UPA Co., Ltd. Microtrac Bell). rice field. The peak of the volume particle size distribution data (histogram) obtained at this time was taken as the average particle size.

<Weight average molecular weight>
The weight-average molecular weight of the resin was obtained by dissolving the dried resin in tetrahydrofuran (THF) to prepare a 0.2% solution, and further filtering through a membrane filter (13HP045AN manufactured by ADVANTEC, pore size 0.45 μm). was measured using the apparatus and measurement conditions of Resins that do not completely dissolve in THF or that dissolve but do not pass through the filter are considered to have sufficiently high molecular weights, and the molecular weight is set at 2,000,000 or more.
Apparatus: HLC-8320-GPC system (manufactured by Tosoh Corporation)
Column: TSKgel-Super Multipore HZ-M0021488 4.6 mmI. D. × 15 cm × 3 (molecular weight measurement range 2000 to about 2000000)
Elution solvent: Tetrahydrofuran Standard substance: Polystyrene (manufactured by Tosoh Corporation)
Flow rate: 0.6 mL/min Sample solution usage: 10 μL
Column temperature: 40°C

<Viscosity at 25°C specified in JIS Z8803>
Based on JIS Z8803, measurement was performed at a measurement temperature of 25° C. using a rotational viscometer (Toki Sangyo B-type viscometer: TVB-10, measurement conditions: rotor No. 2, rotor rotation speed 60 rpm).

<Viscosity _V1 , Viscosity _V2 >
Viscosity V ₁ and viscosity V ₂ were measured using a rheometer using MCR302 manufactured by Anton Paar. Using a cone plate (60 mm, 1°), measurement was performed at a measurement temperature of 25°C.

<Transmittance>
The transmittance of the resin was measured using an ultraviolet-visible-near-infrared spectrophotometer (V-770D manufactured by JASCO Corporation). A resin solution prepared by diluting with water so that the solid content of the resin was 5% was added to the glass cell, and the transmittance at a wavelength of 660 nm was measured. When measuring transmittance, it is necessary to use a resin solution in which a single resin is diluted with water. In addition to the resin, other substances such as inorganic fillers and waxes that change the transmittance are included. must not.

<Production of water-insoluble resin aqueous dispersions (b1 to b6)>
[Aqueous dispersion (b1) of water-insoluble resin (polyester resin)]
A mixture of 2492 g of terephthalic acid, 415 g of isophthalic acid, 1516 g of sebacic acid, 1210 g of ethylene glycol and 1484 g of neopentyl glycol was heated in an autoclave at 250° C. for 5 hours for esterification reaction. After adding 3.3 g of zinc acetate dihydrate as a catalyst, the temperature of the system was raised to 275° C., and the pressure of the system was gradually reduced to 13 Pa after 1.5 hours. Under these conditions, the polycondensation reaction was continued for an additional 4 hours, the system was brought to normal pressure with nitrogen gas, the temperature of the system was lowered, and when the temperature reached 265°C, 29 g of trimellitic anhydride was added and stirred at 265°C for 2 hours. A depolymerization reaction was carried out. After that, the system was pressurized with nitrogen gas, and the resin was discharged in sheet form. After cooling at room temperature, a sheet-like polyester resin was obtained. 400 g of the obtained sheet-like polyester resin and 600 g of methyl ethyl ketone (MEK) were put into a 3 L polyethylene container, and the container was heated with warm water of about 60° C. and stirred with a stirrer to completely obtain a polyester resin. was dissolved in MEK to obtain a polyester resin solution with a solid content concentration of 40% by mass.
Then, 500 g of the above polyester resin solution was charged into a jacketed glass container, cooled water was passed through the jacket to maintain the temperature of the system at 13° C., and the mixture was stirred with a stirrer. Then, while stirring, 23.3 g of triethylamine was added as a basic compound, and water was added at a rate of 100 g/min to obtain an aqueous dispersion (b1) of a polyester resin having a nonvolatile content of 35%. . The obtained (b1) was diluted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 10%.

[Aqueous dispersion (b2) of water-insoluble resin (acrylic resin)]
A reaction vessel (reaction tank) equipped with a stirrer, a thermometer, a dropping funnel and a reflux vessel was charged with 83.6 parts of water and 0.35 parts of Emal 0 (sodium lauryl sulfate, active ingredient 100% manufactured by Kao Corporation). Separately, 30.0 parts of ethyl acrylate, 53.0 parts of methyl methacrylate, 7.0 parts of n-butyl acrylate, 10.0 parts of methacrylic acid, 3.9 parts of t-dodecyl mercaptan, 0.80 parts of emal, 52 parts of water 9 parts were previously mixed and stirred to prepare an ethylenically unsaturated monomer emulsified liquid to be dropped in the first stage (first dropping vessel). After the internal temperature of the reaction vessel was raised to 80° C. and the contents were sufficiently replaced with nitrogen, 5.5 parts of a 5% aqueous solution of potassium persulfate was added as an initiator to initiate emulsion polymerization. While maintaining the internal temperature at 80° C., the ethylenically unsaturated monomer emulsion and 5.5 parts of a 5% potassium persulfate aqueous solution were added dropwise over 2 hours. After the completion of dropping of the ethylenically unsaturated monomer emulsion in the first stage, after 30 minutes, 30.0 parts of ethyl acrylate, 50.0 parts of methyl methacrylate, 10.0 parts of n-butyl methacrylate, and 20 parts of n-butyl acrylate. .0 parts, acrylic acid 2.0 parts, 2-ethylhexyl acrylate 15.0 parts, cyclohexyl acrylate 2.0 parts, glycidyl methacrylate 1.0 parts, diethylene glycol dimethacrylate 1.0 parts, t-dodecyl mercaptan 0.1 parts , 1.20 parts of Emal 0 and 160.8 parts of water were previously mixed and stirred to prepare the second-stage ethylenically unsaturated monomer emulsion (second-stage dropping tank) and 10% of ammonium persulfate 11.1 parts of the aqueous solution was added dropwise over 2 hours. After the dropping was completed, the mixture was allowed to react at 80° C. for another 3 hours. After completion of the reaction, 9.8 parts of 25% aqueous ammonia was added with stirring to neutralize and the acrylic resin was dispersed in the water. Further, water was added to adjust the non-volatile content to 35%, thereby obtaining the desired acrylic resin aqueous dispersion (b2). The obtained (b2) was diluted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 8%. The obtained acrylic resin had a Tg of 8.4° C. and 56.4° C., an acid value of 33.8 mgKOH/g, and an average particle size of 200 nm. Moreover, since the acrylic resin was insoluble in THF, the weight average molecular weight was set to 2,000,000 or more.

[Aqueous dispersion (b3) of water-insoluble resin (acrylic-modified urethane resin)]
First, 14.6 parts of polytetramethylene glycol (PTG-2000SN manufactured by Hodogaya Chemical Co., Ltd., number of functional groups: 2, hydroxyl value: 57.0 mgKOH/g) as a polyol was placed in a reaction vessel equipped with a stirrer, a thermometer, and a reflux device. (Kuraray P-2011 functional group number 2, hydroxyl value 56.0 mgKOH/g) 20.2 parts, polycarbonate polyol (Kuraray C-2090 functional group number 2, hydroxyl value 56.3 mgKOH/g) 48.6 parts, dimethylol 4.3 parts of butanoic acid, 0.1 part of neopentyl glycol, and 9.7 parts of isophorone diisocyanate as polyisocyanate were charged, and the temperature was raised to 80° C. while stirring in a nitrogen atmosphere. Then, 0.02 part of titanium diisopropoxybis (ethyl acetoacetate) was added, and the temperature was raised to 110°C and reacted for 5 hours, after which the temperature was lowered to 80°C. At this time, the weight average molecular weight of the urethane prepolymer produced was 32,100.
Then, 40.0 parts of methyl ethyl ketone and 2.4 parts of 2-aminoethanethiol were added and reacted at 75° C. for 2 hours. The end point of the reaction was confirmed by the disappearance of the isocyanato group-derived peak (around 2270 cm ⁻¹ ) by FT-IR. Further, methyl ethyl ketone was added to adjust the solid content concentration to 70% to obtain a solution of urethane resin U1 having sulfanyl groups at both ends. Next, 50 parts of the solution of urethane resin U1 obtained above, 5.0 parts of styrene, 13.0 parts of methyl methacrylate, and n-butyl acrylate were added to a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux device. 9.0 parts of methacrylic acid, 2.0 parts of diacetone acrylamide, 1.0 parts of diacetone acrylamide, 18.0 parts of RUVA-093, 2.0 parts of Adekastab LA-82, 35.0 parts of n-propanol were added, nitrogen The temperature was raised to 75° C. while stirring in an atmosphere. 20.0 parts of methyl ethyl ketone and 0.35 parts of 2,2′-azobis(2,4-dimethylvaleronitrile) as an initiator were charged into the dropping funnel and added dropwise to the reactor over 5 hours. The reaction was carried out at 78° C. for 8 hours to complete the grafting reaction of the acrylic resin (c) portion. After the reaction, 10 parts of water was added, and 25% aqueous ammonia was added so as to equimolar the carboxyl groups in the resin for neutralization to remove the solvent. Water was added to the resulting aqueous dispersion to adjust the non-volatile content to 35%, thereby obtaining the objective aqueous dispersion (b3) of acrylic-modified urethane resin. The obtained (b3) was adjusted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 5%.

[Aqueous dispersion (b4) of water-insoluble resin (polylactic acid-based polyester resin)]
8.7 parts of polyglycerol ethylene oxide adduct (number average molecular weight 1000), 67.3 parts of L-lactide, 16.8 parts of D-lactide and a catalyst were placed in a 500 ml glass flask equipped with a thermometer, stirrer and Liebig condenser. 0.028 part of tin octylate was charged as a solution, and nitrogen gas was passed through at 60° C. for 30 minutes. Then, the pressure was reduced to 60° C. for 30 minutes to further dry the contents. The temperature of the polymerization system was raised to 180°C while nitrogen gas was circulated again, and after reaching 180°C, stirring was continued for 3 hours. Then, 0.018 part of phosphoric acid was added, and after stirring for 20 minutes, the system was evacuated to distill off unreacted lactide and caprolactone. About 20 minutes later, after the unreacted substances stopped distilling, 5.5 parts of succinic anhydride was added and stirred at 180°C for 2 hours, then the content was taken out and cooled. A 500 ml glass flask equipped with a thermometer, a stirrer, and a Liebig condenser was charged with 25 parts of polylactic acid-based polyester resin and 1.0 part of TEA, and ion-exchanged water was added so that the non-volatile content was adjusted to 35%. . After that, the temperature was raised to 70° C. and the mixture was stirred for 1 hour, and then the content was taken out and cooled to obtain the objective aqueous dispersion (b4) of the polylactic acid-based polyester resin. The obtained (b4) was adjusted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 13%.

[Aqueous dispersion (b5) of water-insoluble resin (polylactic acid-based polyester resin)]
A 500 ml glass flask equipped with a thermometer, a stirrer and a Liebig condenser was charged with 8.7 parts of polyglycerin ethylene oxide adduct (number average molecular weight 1000), 74.4 parts of L-lactide, 15.2 parts of ε-caprolactone and a catalyst. 0.028 part of tin octylate was charged as a solution, and nitrogen gas was passed through at 60° C. for 30 minutes. Then, the pressure was reduced to 60° C. for 30 minutes to further dry the contents. The temperature of the polymerization system was raised to 180°C while nitrogen gas was circulated again, and after reaching 180°C, stirring was continued for 3 hours. Then, 0.018 part of phosphoric acid was added, and after stirring for 20 minutes, the system was evacuated to distill off unreacted lactide and caprolactone. About 20 minutes later, after the unreacted substances stopped distilling, 5.5 parts of succinic anhydride was added and stirred at 180°C for 2 hours, then the content was taken out and cooled. 25 parts of polylactic acid-based polyester resin, 1.0 part of TEA, and 75 parts of water were placed in a 500 ml glass flask equipped with a thermometer, a stirrer, and a Liebig condenser, heated to 70° C., stirred for 1 hour, and then the contents were removed. The mixture was taken out and cooled, and water was added to the resulting aqueous dispersion to adjust the non-volatile content to 35%, thereby producing the intended aqueous dispersion (b5) of the polylactic acid-based polyester resin. The obtained (b5) was adjusted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 15%.

[Aqueous dispersion (b6) of water-insoluble resin (polylactic acid-containing urethane resin)]
408 parts of 2,2-dimethyl-3-hydroxypropyl-2′,2′-dimethyl-3′-hydroxypropanate, 5-sodium sulfoisophthalic acid were placed in a 1 L glass flask equipped with a thermometer, a stir bar and a Liebig condenser. 197 parts of dimethyl and 0.1 part of tetrabutyl titanate (TBT) catalyst were charged. While distilling off the methanol distilled at 190°C, the reaction was stirred for 1 hour. After confirming the completion of distillation of methanol at 230°C, the temperature was raised to 250°C, the mixture was stirred under reduced pressure for 10 minutes, and the reactant was cooled to 100°C. 141 parts of toluene was mixed and uniformly dissolved to obtain a sulfonic acid-containing diol. Next, 18 parts of NPG, 400 parts of L-lactide, 100 parts of D-lactide, and 0.15 part of tin octylate as a catalyst were charged into a 1 L glass flask equipped with a thermometer, a stirring rod, and a Liebig condenser, and the mixture was stirred at room temperature for 30 minutes. Placed under a stream of nitrogen gas. Then, the pressure was reduced at room temperature for 30 minutes to further dry the contents. The temperature of the reaction system was raised to 180° C. again under a nitrogen gas stream, and the mixture was stirred for 3 hours.
Then, 0.10 part of phosphoric acid was added, and after stirring for 30 minutes, the system was evacuated to distill off unreacted residual lactide. About 20 minutes later, after the distillation of unreacted lactide stopped, the content was taken out and cooled to obtain polylactic acid diol. In a 1 L glass flask equipped with a thermometer, a stirring rod and a condenser, 100 parts of the above-mentioned polylactic acid diol and 62.5 parts of the above-mentioned sodium sulfonate base-containing diol (80% by weight toluene solution) were dissolved in 200 parts of MEK and heated to 50°C. was warmed to Then, 38 parts of MDI were dissolved and 0.4 parts of dibutyltin laurate was added as a catalyst. After reacting at 70° C. for 4 hours, it was diluted with 238 parts of MEK. Then, the mixture was heated to 50° C., and deionized water was gradually added while stirring to mix uniformly. Then, while keeping the contents at 50° C., MEK was distilled off under reduced pressure to remove the MEK/water mixture. After that, by diluting with deionized water so that the non-volatile content becomes 35%, an aqueous dispersion of polylactic acid-containing urethane resin ((b6) is obtained. When the transmittance was measured after preparation, the transmittance was 30%.

[Aqueous dispersion (b7) of water-insoluble resin (acrylic resin)]
A reaction vessel (reaction tank) equipped with a stirrer, a thermometer, a dropping funnel and a reflux vessel was charged with 83.6 parts of water and 0.35 parts of Emal 0 (sodium lauryl sulfate, active ingredient 100% manufactured by Kao Corporation). Separately, 30.0 parts of ethyl acrylate, 46.0 parts of methyl methacrylate, 7.0 parts of n-butyl acrylate, 17.0 parts of methacrylic acid, 3.9 parts of t-dodecyl mercaptan, 0.80 parts of emal, 52 parts of water 9 parts were previously mixed and stirred to prepare an ethylenically unsaturated monomer emulsified liquid to be dropped in the first stage (first dropping vessel). After the internal temperature of the reaction vessel was raised to 80° C. and the contents were sufficiently replaced with nitrogen, 5.5 parts of a 5% aqueous solution of potassium persulfate was added as an initiator to initiate emulsion polymerization. While maintaining the internal temperature at 80° C., the ethylenically unsaturated monomer emulsion and 5.5 parts of a 5% potassium persulfate aqueous solution were added dropwise over 2 hours. After the completion of dropping of the ethylenically unsaturated monomer emulsion in the first stage, after 30 minutes, 30.0 parts of ethyl acrylate, 50.0 parts of methyl methacrylate, 10.0 parts of n-butyl methacrylate, and 20 parts of n-butyl acrylate. .0 parts, acrylic acid 2.0 parts, 2-ethylhexyl acrylate 15.0 parts, cyclohexyl acrylate 2.0 parts, glycidyl methacrylate 1.0 parts, diethylene glycol dimethacrylate 1.0 parts, t-dodecyl mercaptan 0.1 parts , 1.20 parts of Emal 0 and 160.8 parts of water were previously mixed and stirred to prepare the second-stage ethylenically unsaturated monomer emulsion (second-stage dropping tank) and 10% of ammonium persulfate 11.1 parts of the aqueous solution was added dropwise over 2 hours. After the dropping was completed, the mixture was allowed to react at 80° C. for another 3 hours. After completion of the reaction, 9.8 parts of 25% aqueous ammonia was added with stirring to neutralize and dispersed in water. Further, water was added to adjust the non-volatile content to 35%, thereby obtaining the desired acrylic resin aqueous dispersion (b7). The obtained (b7) was adjusted with water to a non-volatile content of 5%, and the transmittance was measured to find that the transmittance was 10%. The obtained resin had a Tg of 8.4° C. and 46.2° C., an acid value of 43.4 mgKOH/g, and an average particle size of 180 nm. Moreover, since the resin was insoluble in THF, the weight average molecular weight was set to 2,000,000 or more.

The materials in Table 1 are as follows.
modified starch (a);
Pyostarch LV (manufactured by Nippon Starch Chemical Co., Ltd., hydroxypropylated starch, Mw 100000, degree of substitution 0.1, transmittance 96%)
SK-20 (manufactured by Japan Corn Starch Co., Ltd., oxidized starch, transmittance of 85%)
Buribain P-63 (manufactured by Nippon Starch Chemical Co., Ltd., starch phosphate, Mw 5600, transmittance 88%)
polyvinyl alcohol;
Exeval RS2117 (manufactured by Kuraray Co., Ltd., modified polyvinyl alcohol, Mw74800, transmittance 90%)
Aqueous dispersion of water-insoluble resin (b);
Superflex SF-170 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin water dispersion, pH 7-9, average particle size 10 μm, transmittance 45%, non-volatile content 33%)

<Manufacture of coating liquid>
[Production Example 1]
70 parts of water and 30 parts of biostarch LV (manufactured by Nippon Starch Chemical Co., Ltd.) were added to a reaction vessel (reaction vessel) equipped with a stirrer, thermometer, dropping funnel, and reflux vessel, and the temperature of the reaction vessel was brought to 85°C while stirring. The temperature was raised to After that, the mixture was stirred for 2 hours to prepare a solution. Then, 5 parts of IPA was added and stirred for 10 minutes to obtain a desired coating liquid. The viscosity of the resulting coating liquid was measured using a Brookfield viscometer and found to be 100 mPa·s. The non-volatile content was 29%. Viscosity measurements were performed with a rheometer, and the viscosity _V1 was 90 mPa·s and the viscosity _V2 was 120 mPa·s.

[Production Examples 2 to 11]
A coating liquid was obtained in the same manner as in Production Example 1, except that the composition was changed to that shown in Table 1. Viscosity measurement with a Brookfield viscometer, viscosity measurement with a rheometer, and non-volatile content measurement were performed on each of the obtained coating liquids.
[Production Example 12]
100 parts of the water-insoluble resin (polyester resin) aqueous dispersion (b1) was added to a reaction vessel (reaction vessel) equipped with a stirrer, thermometer, dropping funnel and reflux device, and stirred at room temperature. After that, a coating liquid was obtained by adding a mixture of 15 parts of water and 0.5 parts of IPA while stirring. The viscosity of the resulting coating liquid was measured using a Brookfield viscometer and found to be 150 mPa·s. The non-volatile content was 30%. Viscosity measurements were performed with a rheometer, and the viscosity _V1 was 120 mPa·s and the viscosity _V2 was 300 mPa·s.
[Production Examples 13 to 19]
A coating liquid was obtained in the same manner as in Production Example 12, except that the composition was changed to that shown in Table 1. Viscosity measurement with a Brookfield viscometer, viscosity measurement with a rheometer, and non-volatile content measurement were performed on each of the obtained coating liquids.

<Production of laminate>
[Example 1]
First, the coating liquid of Production Example 1 is applied to the glossy side of commercially available sanitary paper (weighing 21 g, one side glossy treated) using a "SOLOFLEX" central impression (CI) type 6-color flexographic printing machine manufactured by Windmirror & Helscher. was applied, and then the coating liquid of Production Example 11 was applied continuously. The coating amount was adjusted so that the coating film weight ratio after drying was 5:5 between the first layer and the second layer. After that, it was dried in an oven at 80° C. to obtain a laminate. The coating amount of the laminate was measured and found to be 2 g/m ² .

[Examples 2 to 22, 25]
Laminates were produced in the same manner as in Example 1, except that the composition, coating amount, and ratio of the first layer to the second layer shown in Tables 2 and 3 were changed.

[Example 23]
Using a simple gravure coating machine (GRAVO-PROOF MINI manufactured by Nissho Gravure Co., Ltd.), the coating liquid of Production Example 1 is applied to the glossy side of commercially available sanitary paper (weight: 21 g, one side gloss-treated), followed by heating in an oven at 80°C. dried with After that, the coating solution of Production Example 12 was applied on the first layer and dried in an oven at 80°C. The coating amount was adjusted so that the coating film weight ratio after drying was 5:5 between the first layer and the second layer. The coating amount of the laminate was measured and found to be 2 g/m ² .

[Example 24]
The coating liquid of Production Example 1 was applied to the glossy side of commercially available sanitary paper (weighing 21 g, one side glossy) using a bar coater, and dried in an oven at 80°C. Thereafter, the coating liquid of Production Example 11 was applied onto the first layer and dried in an oven at 80°C. The coating amount was adjusted so that the coating film weight ratio after drying was 5:5 between the first layer and the second layer. The coating amount of the laminate was measured and found to be 2 g/m ² .

[Comparative Examples 1 to 10]
Laminates were produced in the same manner as in Example 1, except that the composition, coating amount, and ratio of the first layer to the second layer shown in Table 3 were changed.

The evaluation method of the laminate is as follows.

<Air shielding>
The air shielding property in the present invention was measured by the method described in the section on air shielding property.
The obtained laminate was cut into a piece of 5 cm×5 cm. The laminate was placed under reduced pressure so that the coated surface was aligned with the glass filter surface. At this time, the laminate and the surface of the glass filter were completely brought into close contact so that the laminate would not be folded and wrinkled. After the laminated body was placed at the measurement site, the value of the degree of pressure reduction was read after the numerical value of the vacuum gauge stabilized, and it was taken as the value of the air shielding property. The measurement was performed in a constant temperature and humidity room with a temperature of 25° C. and a humidity of 60%.

<Blocking property test>
The coated surface and the non-coated surface of the laminate thus obtained were overlapped, and the blocking resistance was measured using the following apparatus and measurement conditions.
Equipment: CO-201 permanent strain tester (manufactured by Tester Sangyo Co., Ltd., upper and lower plate heating)
Conditions: 2kg/cm ² -40°C - 24hrs
[Evaluation criteria]
S: There is no resistance when peeling, and the paper is not damaged (extremely good)
A: There is a little resistance when peeling, but the paper is not damaged (good)
B: There is resistance when peeling, but the paper is not damaged (can be used)
C: There is a sense of resistance when peeling, and the paper is also missing (unusable)

<Heat sealability>
The obtained laminate was cut into a width of 15 mm, and the cut piece was used as a test piece to measure the heat seal strength using the following equipment and measurement conditions.
(heat seal)
Equipment: HEATSHEEL & IMPULSE TESTER (manufactured by Nichirikagaku Kogyo Co., Ltd., upper and lower plate heating)
Heat sealing conditions: 130° C.-2 kgf/cm ² -1 second (peeling)
Equipment: Tensile tester (manufactured by Tester Sangyo Co., Ltd.)
Peeling conditions: 180° peeling, 300 mm/min [Evaluation criteria]
S: 2N or more (extremely good)
A: 1.5 N or more and less than 2 N (good)
B: 1N or more and less than 1.5N (usable)
C: less than 1N (cannot be used)

<Oil resistance>
One drop of castor oil was dropped on the coated surface of the obtained laminate in an environment of 23° C., and after 30 seconds, it was confirmed whether or not the castor oil had permeated onto the laminate. Evaluation was made by the rate at which the color of the paper was changed due to the permeation of the area onto which the castor oil was dripped.
[Evaluation criteria]
S: Penetration is not seen at all (extremely good)
A: The soaked area is less than 10% (good)
B: The soaked area is 10% or more and less than 50% (usable)
C: 50% or more of the soaked area (extremely poor)

<Water resistance>
In an environment of 23° C., one drop of water was dropped on the coated surface of the obtained laminate, and after 30 seconds, it was confirmed whether or not the water had soaked into the laminate. Evaluation was made based on the rate of discoloration of the paper due to the penetration of the water-dropped area.
[Evaluation criteria]
S: Penetration is not seen at all (extremely good)
A: The soaked area is less than 10% (good)
B: The soaked area is 10% or more and less than 50% (usable)
C: 50% or more of the soaked area (extremely poor)

<Biodegradability test>
A film having a thickness of 0.5 mm, a length of 10 cm, and a width of 10 cm is prepared by drying the coating liquid used to prepare the laminate, and the film is buried in compost for one month. A film prepared with the coating liquid used for preparing the first coating layer is referred to as a test piece α, and a film prepared with the coating liquid used for the second coating layer is referred to as a test piece β. Assume that the total volume of test piece α and test piece β is 100%.
[Evaluation criteria]
S: Less than 60% of the residue that can be visually confirmed (extremely good)
A: Residue that can be visually confirmed is 60% or more and less than 70% (good)
B: Residue that can be visually confirmed is 70% or more and less than 90% (usable)
C: Residue that can be visually confirmed is 90% or more (extremely poor)

According to the results in Tables 2 and 3, the coated article prepared by using modified starch for the first coating layer of the present invention and using a water-insoluble resin for the second coating layer is oil resistant. It had excellent properties, water resistance, heat seal strength and blocking property. In particular, Example 1, which uses hydroxypropylated starch in the first coating layer, exhibits excellent oil resistance and water resistance compared to Example 9, which uses phosphated starch in the first coating layer. Indicated.
On the other hand, in Comparative Examples 1 and 2, although polyvinyl alcohol was used for the first coating layer, the oil resistance and water resistance were significantly lowered. Comparative Example 8, in which a polyester resin was used for the first layer, showed no biodegradability.

1 Glass container 2 Glass filter 3 Rubber tube 4 Hydraulic pump 5 Vacuum gauge 6 Filter part 7 Laminate (measurement sample)

Claims (9)

Having a first coating layer (A) on at least one of the paper substrates,
Furthermore, a laminate having a second coating layer (B) on the first coating layer,
The first coating layer (A) comprises at least one modified starch (a),
and,
The second coating layer (B) contains at least one water-insoluble resin (b),
The total coating amount of the first coating layer (A) and the second coating layer (B) is 0.5 to 10 g / m ² , and
A laminate having an air shielding property of 20 kPa or less. 2. A coating liquid for forming the first coating layer (A) of the laminate according to claim 1, which satisfies the following formula (1).
formula (1)
V ₂ ≤ 1.5 x V ₁
(V ₁ : Viscosity 5 seconds after applying a shear rate of 2000 (l / s) to the coating liquid, V ₂ : 5 seconds after applying a shear rate of 50 (l / s) to the coating liquid viscosity) 3. The coating liquid according to claim 2, which has a solid content of 5 to 40% and a viscosity at 25° C. of 5 to 500 mPa·s as defined in JIS Z8803. The laminate according to claim 1, which has a first coating layer (A) formed from the coating liquid according to claim 2 or 3. 5. The laminate according to claim 1, wherein the water-insoluble resin (b) contains at least one of acrylic resin (c), polyester resin (d), and urethane resin (e). Claim 1, wherein the mass ratio ((A)/(B)) per unit area of the first coating layer (A) and the second coating layer (B) is 2/8 to 8/2. , 4 or 5. The method for producing a laminate according to any one of claims 1 and 4 to 6, wherein the first coating layer (A) and the second coating layer (B) are formed by gravure printing or flexographic printing. . The laminate according to any one of claims 1 and 4 to 7, wherein the modified starch (a) is a modified starch obtained by hydroxyalkylating or oxidizing a starting starch. A food packaging sheet for enclosing food, comprising the laminate according to any one of claims 1 and 4 to 8.

Images