JP2008239830A - Aqueous coating composition, composite sheet, decorative sheet and decorative material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous coating composition good in adhesion to a natural material or a biodegradable material, having high water resistance and little influence on the environment, and to provide a composite sheet obtained by using the aqueous coating composition, a decorative sheet having the composite sheet and a decorative material having the decorative sheet. <P>SOLUTION: The aqueous coating composition consists of an aqueous solution or an aqueous dispersion containing an oxidized polysaccharide obtained by oxidizing a polysaccharide and a compound having two or more reactive functional groups in one molecule. The composite sheet is obtained by coating the above aqueous coating composition on a substrate sheet composed of an aliphatic polyester type resin and/or a plant-derived resin. Alternatively the composite sheet is obtained by coating and/or impregnating a substrate sheet composed of a natural fiber with the above aqueous coating composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aqueous coating composition, a composite sheet using the aqueous coating composition, a decorative sheet using the composite sheet, and a cosmetic material using the decorative sheet.

Due to the recent increase in awareness of environmental problems, development of products using natural materials or biodegradable materials has been actively conducted. From these trends in the world, the use of plant-derived resin films typified by polylactic acid, non-woven fabrics made of plant fibers, paper, etc. is being reviewed, and various packaging materials, industrial materials, building materials, etc. The use for is being considered.
In these applications, printing is generally performed on a material to be used, or other layers such as an adhesive layer and a sealant layer are bonded together. However, when a natural material or a biodegradable material is used as a material, there are still many problems to be solved for printing and pasting techniques, particularly when a film made of plant-derived resin is used. One of the major problems is insufficient adhesion of ink and adhesive to these materials.

On the other hand, it has been proposed to use polysaccharides for modifying paper and resin films. Various polysaccharides such as cellulose, starch, mucopolysaccharide (for example, chitin), and derivatives thereof are used as polysaccharides, which are the most abundant carbohydrates on earth.
As a method for derivatizing a polysaccharide, a method of introducing a substituent into a hydroxyl group of the polysaccharide is mainly used. However, the production of these derivatives usually requires the use of many highly toxic substances and large amounts of organic solvents, which are not in line with the original purpose of dealing with environmental problems.
A method for oxidizing polysaccharides has also been proposed. In recent years, research has been conducted on a method called TEMPO catalytic oxidation (see Non-Patent Document 1, for example). In this method, a polysaccharide is oxidized in an aqueous solution or dispersion of a polysaccharide using 2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO) as a catalyst, and the hydroxyl group of the polysaccharide is converted. This is a technique of converting to a formyl group, a carboxyl group or a salt thereof to make it hydrophilic.
Y. Kato et al., Carbohydrate Polymers, 51, 69-75 (2003).

  However, in the prior art, there are various problems when trying to modify natural materials or biodegradable materials using polysaccharides. For example, even when any polysaccharide is used, the adhesion to natural materials and biodegradable materials is poor, and the water resistance is insufficient. In particular, starch and starch derivatives have low water resistance. Cellulose and chitin are difficult to dissolve in water and other solvents, and are difficult to use as an aqueous solution or aqueous dispersion. Furthermore, when derivatization is performed to improve the solubility, if the synthesized derivative is a substance that does not exist in nature, it may adversely affect the environment or the living body if it is discarded in the environment. There is.

  The present invention has been made in view of the above circumstances, and has good adhesion to natural materials and biodegradable materials, has high water resistance, and has little impact on the environment. It aims at providing the composite sheet obtained using a composition, the decorative sheet which has this composite sheet, and the decorative material which has this decorative sheet.

A first aspect of the present invention that solves the above problems is an aqueous solution or aqueous dispersion containing an oxidized polysaccharide obtained by oxidizing a polysaccharide and a compound having two or more reactive functional groups in one molecule. An aqueous coating composition characterized by comprising:
A second aspect of the present invention is a composite sheet obtained by applying the aqueous coating composition of the first aspect of the present invention to a base sheet composed of an aliphatic polyester resin and / or a plant-derived resin ( Hereinafter, it may be referred to as a composite sheet (1).
A third aspect of the present invention is a composite sheet obtained by impregnating or applying the aqueous coating composition of the first aspect of the present invention to a base sheet composed of natural fibers (hereinafter referred to as composite sheet (2)). There is.)
A fourth aspect of the present invention is a decorative sheet having the composite sheet of the second or third aspect.
The fifth aspect of the present invention is a wood decorative material obtained by bonding at least the decorative sheet of the fourth aspect to a base material.

  According to the present invention, an aqueous coating composition having good adhesion to a natural material or biodegradable material, having high water resistance and little impact on the environment, a composite sheet obtained using the aqueous coating composition, A decorative sheet having the composite sheet and a decorative material having the decorative sheet can be provided.

The present invention is described in detail below.
<Water-based coating composition>
[Oxidized polysaccharide]
An oxidized polysaccharide is obtained by oxidizing a polysaccharide. As the polysaccharide to be oxidized, water-soluble polysaccharides such as starch, pullulan and hyaluronic acid, cellulose, chitin / chitosan and the like can be used. Starch, cellulose and chitin / chitosan are preferable in consideration of the procurement of raw materials, costs, expected functions, and the advantage that they can be water-solubilized with almost no change in structure.
Here, chitin / chitosan is a polysaccharide composed of a polymer in which N-acetylglucosamine residues and / or glucosamine residues are linked.
Chitin / chitosan is a polysaccharide mainly contained in crabs, shrimp shells and insect shells, and in the natural state it is said to consist of almost N-acetylglucosamine residues. It is believed that the treatment during isolation from these advances deacetylation and increases the proportion of glucosamine residues.
Generally, those having a higher proportion of N-acetylglucosamine residues than the proportion of glucosamine residues are called chitin, and those having a higher proportion of glucosamine residues than the proportion of N-acetylglucosamine residues are called chitosan.
The ratio of the N-acetylglucosamine residue and the glucosamine residue can be controlled at an arbitrary ratio by N-acetylation of the amino group of the glucosamine residue or deacetylation reaction of the N-acetylglucosamine residue.
In the present invention, the polysaccharide is preferably at least one selected from the group consisting of starch, cellulose, chitin and chitosan.

There are many possible methods for oxidizing the polysaccharide, but N-oxyl compounds such as 2,2,6,6-tetramethylpiperidinyloxy radical (hereinafter abbreviated as TEMPO) are used as catalysts. Preferred oxidation methods.
In the present invention, a method of oxidizing a polysaccharide in water in the presence of an N-oxyl compound is preferable. Thereby, an aqueous solution or an aqueous dispersion containing the oxidized polysaccharide is obtained. Such an aqueous solution or aqueous dispersion can be used as it is for the production of the aqueous coating composition of the present invention. For example, the aqueous coating composition of the present invention can be obtained by adding a compound having two or more reactive functional groups in one molecule to the aqueous solution or aqueous dispersion.
Examples of N-oxyl compounds include TEMPO, 2,2,6,6-tetramethylpiperidine-N-oxyl, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, 2,2 , 6,6-tetramethyl-4-phenoxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-benzylpiperidine-1-oxyl, 2,2,6,6-tetramethyl-4- Acryloyloxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-methacryloyloxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-benzoyloxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-cinnamoyloxypiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-acetylamino Piperidine-1-oxyl, 2,2,6,6-tetramethyl-4-acryloylaminopiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-methacryloylaminopiperidine-1-oxyl, 2, 2,6,6-tetramethyl-4-benzoylaminopiperidine-1-oxyl, 2,2,6,6-tetramethyl-4-cinnamoylaminopiperidine-1-oxyl, 4-propionyloxy-2,2, 6,6-tetramethylpiperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N- Oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl Peridine-N-oxyl, 2,2,4,4-tetramethylazetidine-1-oxyl, 2,2-dimethyl-4,4-dipropylazetidine-1-oxyl, 2,2,5,5- Tetramethylpyrrolidine-N-oxyl, 2,2,5,5-tetramethyl-3-oxopyrrolidine-1-oxyl, 2,2,6,6-tetramethyl-4-acetoxypiperidine-1-oxyl, di-tert -Butylamine-N-oxyl, poly [(6- [1,1,3,3-tetramethylbutyl] amino) -s-triazine-2,4-diyl] [(2,2,6,6-tetramethyl -4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino and the like.

The oxidized polysaccharide may be water-soluble, poorly water-soluble or water-insoluble. When the oxidized polysaccharide is water-soluble, the oxidized polysaccharide can be used as an aqueous solution, and when the oxidized polysaccharide is hardly water-soluble or water-insoluble, the oxidized polysaccharide can be used as an aqueous dispersion. Since it is excellent in terms of uniformity, transparency (refractive index), smoothness, and adhesion of a coating film obtained by coating, it is preferably water-soluble.
When obtaining a water-soluble material using a highly crystalline polysaccharide such as cellulose or chitin as a raw material, the raw material may be subjected to a treatment for reducing the crystallinity such as a regeneration treatment as a pretreatment. preferable.
Here, “water-soluble” means that the weight of the residue when an aqueous solution of an arbitrary concentration is filtered through a 5 μm membrane filter is 1% or less of the total solid content.

In the present invention, it is particularly preferable to carry out the oxidation method in water in the presence of an N-oxyl compound in combination with a co-oxidant. As a result, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group can be greatly improved.
At this time, bromide or iodide is preferably present in the reaction system as another catalyst.
Co-oxidants include halogens such as bromine, chlorine and iodine, hypohalous acids, halous acids and perhalogen acids, or their salts, halogen oxides, nitrogen oxides, peroxides, etc. Any co-oxidant can be used as long as it can promote the reaction. As a handy co-oxidant, sodium hypochlorite is more preferable.
Examples of bromides include alkali metal bromide salts such as sodium bromide. Examples of the iodide include alkali metal iodide salts such as sodium iodide.
At this time, in the reaction system, the N-oxyl compound is sequentially oxidized by the co-oxidant to produce an oxoammonium salt, and the polysaccharide is oxidized by the oxoammonium salt. This oxidation method can be applied to various polysaccharides such as cellulose, chitin and chitosan from water-soluble polysaccharides such as starch and pullulan.
The polysaccharide thus oxidized has a polyuronic acid type structure in which only the primary hydroxyl group (hydroxyl group bonded to the primary carbon atom) is oxidized with high selectivity and converted into a carboxyl group or a salt thereof. This synthetic polyuronic acid has high hydrophilicity and water solubility depending on the crystallinity of the starting polysaccharide, and the water-solubilized one has a uniform structure consisting of naturally occurring saccharides and has high water solubility. A low-viscosity aqueous solution can be obtained even at high concentrations.
In the TEMPO catalytic oxidation process, a considerable amount of formyl group remains in the form of hemiacetal or the like, unlike a normal oxidation method. The effect of the present invention is presumed to be obtained by interaction (for example, crosslinking reaction) between the formyl group and a compound having two or more reactive functional groups in one molecule in addition to the carboxy group and the hydroxyl group. Is done.

The reaction conditions such as the amount and type of the reagent to be added by the oxidation method, temperature and pH may be any conditions as long as the oxidation of the polysaccharide proceeds to obtain the target polysaccharide, and can be appropriately changed.
The amount of the N-oxyl compound used may be an amount as a catalyst, for example, within the range of 10 ppm to 5% (ppc) with respect to the number of moles of the constituent monosaccharide of the polysaccharide to be oxidized, % Is more preferable.
The amount of co-oxidant used greatly affects the degree of oxidation of the resulting oxidized polysaccharide, and is preferably 1 to 400%, more preferably 5 to 250%, more preferably 160 to 160 mol of the primary hydroxyl group of the polysaccharide. More preferred is ~ 250%.
The amount of bromide or iodide used can be selected within a range that can promote the oxidation reaction. For example, 0 to 100% is preferable and 1 to 50% is the number of moles of the constituent monosaccharide of the polysaccharide. More preferred.
The reaction temperature is preferably room temperature (30 ° C.) or less and more preferably 5 ° C. or less for the purpose of improving the selectivity of oxidation of the constituent monosaccharides to primary hydroxyl groups and suppressing side reactions. Although the minimum of reaction temperature is not specifically limited, 0 degreeC or more is preferable.
Furthermore, it is preferable to keep the inside of the system alkaline during the reaction. The pH at this time is preferably 9 to 12, and more preferably pH 10 to 11. The pH can be adjusted by adding an alkali such as sodium hydroxide or potassium hydroxide.

Furthermore, in the above oxidation method, the degree of oxidation of the polysaccharide can be controlled by the amount of co-oxidant and the amount of alkali added when the pH is kept constant. For example, if a primary hydroxyl group equivalent to a polysaccharide and an equivalent amount of an oxidant are added twice as much as an oxidizing agent, almost all primary hydroxyl groups at the 6-position of the pyranose ring are oxidized to carboxyl groups, and water-soluble polyuronic acid is converted into water. can get.
This oxidized polysaccharide is highly water-soluble and can be made into an aqueous solution. In particular, since an aqueous solution of water-soluble polyuronic acid has a relatively low viscosity even at a high concentration, the solid content concentration is increased (for example, in order to reduce drying load or increase the reaction efficiency with a reactive functional group such as isocyanate (for example, 1 to 50% by mass).

  In the aqueous coating composition of the present invention, the concentration of the oxidized polysaccharide can be freely selected depending on the use, purpose and desired physical properties of the aqueous coating composition, but from the viewpoint of viscosity, drying, reaction efficiency, etc. 0.1 to 50% by mass is preferable, and 5 to 20% by mass is more preferable.

[Compound having two or more reactive functional groups in one molecule]
The reactive functional group in a compound having two or more reactive functional groups in one molecule (hereinafter sometimes referred to as a polyfunctional compound) is a reactive group (hydroxyl group, amino group, formyl group, It is a functional group that reacts with a carbonyl group, a carboxy group or a salt thereof (COO ⁻ )), and reacts with the reactive group to form a cross-link or functions as a side chain role that imparts functionality.
Examples of reactive functional groups include isocyanate groups, carbodiimide groups, blocked isocyanate groups, epoxy groups, oxazoline groups, amino groups, hydroxyl groups, formyl groups, halohydrin groups, hydrazide groups, among these, isocyanate groups, carbodiimides At least one selected from the group consisting of a group, a blocked isocyanate group, an epoxy group, an oxazoline group and an amino group is preferred.
Here, the blocked isocyanate group is a functional group that prevents the isocyanate group from being consumed by reacting with water existing in the system or in the air, or reacts with the isocyanate group and the isocyanate group in one liquid. For the purpose of prolonging the pot life of the system in which both groups can exist, the isocyanate group is protected (blocked), and the block is removed by irradiation with heat or radiation to generate an isocyanate group. Blocking agents used for blocking isocyanate groups include oximes [acetooxime, methyl isobutyl ketoxime, diethyl ketoxime, cyclopentanone oxime, cyclohexanone oxime, methyl ethyl ketoxime, etc.]; lactams [γ-butyrolactam, ε-caprolactam , Γ-valerolactam, etc.]; aliphatic alcohols having 1 to 20 carbon atoms [ethanol, methanol, octanol, etc.]; phenols [phenol, m-cresol, xylenol, nonylphenol, etc.]; active methylene compounds [N, N-diethyl Hydroxylamine, 2-hydroxypyridine, pyridine-N-oxide, 2-mercaptopyridine and the like]; and mixtures of two or more thereof. Of these, oximes are preferred, and methyl ethyl ketoxime is particularly preferred.
In a polyfunctional compound, the number of reactive functional groups should just be two or more, and is not specifically limited.
The reactive functional group contained in one molecule of the polyfunctional compound may be one type or two or more types.
Polyfunctional compounds also include urethane prepolymers having the above reactive functional groups at the polymer ends, and polymers such as polyisocyanates and polycarbodiimides.

As the polyfunctional compound, an isocyanate compound having an isocyanate group, a carbodiimide compound having a carbodiimide group, and an epoxy compound having an epoxy group are preferable as the reactive functional group, and an isocyanate compound and / or a carbodiimide compound are more preferable. Each of these compounds may have a reactive functional group other than an isocyanate group, a carbodiimide group, and an epoxy group.
Isocyanate compounds include aromatic diisocyanates such as phenylene diisocyanate (PDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), 4,4 ′ diisocyanate diphenylmethane (MDI), and xylylene diisocyanate (XDI). Aliphatic or alicyclic diisocyanates such as aliphatic diisocyanates, hydrogenated TDI, hydrogenated XDI, hydrogenated MDI, hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and polyol adducts or burettes which are derivatives thereof, Trifunctional or higher functional polyisocyanate obtained by reacting 3 or more molecules of the above diisocyanate, trifunctional isocyanate such as lysine triisocyanate (LTI), Examples include various oligomers and polymers containing a cyanate group.
Examples of the carbodiimide compound include oligomers and polymers containing a carbodiimide group such as polycarbodiimide.
As an epoxy compound, a both-ends epoxy compound or a polyvalent epoxy compound is preferable. Examples of the polyvalent epoxy compound include glycidyl ether epoxy compounds, alicyclic epoxy compounds, glycidyl amine epoxy compounds, and the like.

In the aqueous coating composition of the present invention, the blending ratio of the polyfunctional compound is such that the number of reactive functional groups in the polyfunctional compound is 0.1 to 250% with respect to the number of reactive groups in the oxidized polysaccharide. It is preferable to mix so that it may exist in the range, 1 to 150% is more preferable, and 60 to 120% is more preferable. When it is at least the lower limit of the above range, the water resistance of the coating film to be formed is improved, and when it is not more than the upper limit value, the ratio of oxidized polysaccharide in the coating film, that is, the degree of biomass origin is high, to the environment and human body The influence of is further reduced.
The ratio of “the number of reactive functional groups in the functional compound” to “the number of reactive groups in the oxidized polysaccharide” in the aqueous coating composition is determined by the following procedure.
First, the amount of hydroxyl groups in the polysaccharide is determined in advance. For example, starch and cellulose have three hydroxyl groups in one glucose unit, while chitin has two hydroxyl groups. In the present invention, since the number of carboxy groups and formyl groups introduced into the oxidized polysaccharide by oxidation is equal to the number of hydroxyl groups originally present, the number of reactive groups in the oxidized polysaccharide can be easily obtained.
Further, the number of reactive functional groups in the polyfunctional compound may be a number obtained by a general method for obtaining each functional group. For example, in the case of an isocyanate group, it can be determined from the amine equivalent (grams of isocyanate that reacts with di-n-butylamine to form a urea bond). Moreover, in the case of an epoxy group, it calculates | requires by the method of calculating | requiring the epoxy equivalent of JISK7236: 2001 epoxy resin. Moreover, in the case of a commercial item, the value described in the catalog etc. can be employ | adopted as it is.
Using the number (a) of reactive groups in the oxidized polysaccharide thus obtained and the number (b) of reactive functional groups in the polyfunctional compound, the formula: [(b) / (a)] × 100 The percentage can be determined.

  In addition to the water-based coating composition of the present invention, conventionally known additives can be blended as necessary. Examples of the additives include colorants such as organic pigments, natural dyes, and inorganic pigments, coloring / constitution / metallic / colored pearl pigments, anti-blocking agents such as silica gel and wax, fluidity modifiers, anti-fogging agents, and anti-dripping agents. Examples thereof include an inhibitor, an ultraviolet absorber, an antioxidant, an ultraviolet stabilizer, a matting agent, a polishing agent, a preservative, a curing accelerator, a curing catalyst, a scratch inhibitor, an antifoaming agent and a solvent.

  The aqueous coating composition of the present invention can be produced, for example, by preparing an aqueous solution or aqueous dispersion of an oxidized polysaccharide and adding a polyfunctional compound and optional additives thereto. In addition, the oxidized polysaccharide and the polyfunctional compound may be prepared in advance in an aqueous solution or an aqueous dispersion, respectively, and mixed before use.

The water-based coating composition of the present invention can be applied and / or impregnated on various substrates.
The material of the base material is not particularly limited, for example, various synthetic resins such as polyolefin resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, plant-derived resin such as polylactic acid, kenaf, wood pulp, natural material Etc.
The shape of the substrate may be any shape, and examples thereof include films, nonwoven fabrics, paper, sheets, fibers and the like.
As the base material on which the aqueous coating composition of the present invention is applied and / or impregnated, in particular, as in the composite sheet of the present invention described later, a base material sheet composed of an aliphatic polyester resin and / or a plant-derived resin. Or a base material sheet (for example, paper or a nonwoven fabric) comprised from natural fiber is preferable. The aqueous coating composition of the present invention has good adhesion to these materials. Moreover, since these base sheet is a biomass origin material, the obtained product exhibits a great effect as an environmentally compatible product.

As a method for applying and / or impregnating the aqueous coating composition of the present invention to a substrate, known methods can be used, for example, spray coating, die coating, knife coating, gravure coating, dip coating, bar coating, roll coating, blade. A coat, a curtain coat, a size press, etc. are mentioned. Further, it may be an inline coat or an off-line coat.
The aqueous coating composition may be applied and / or impregnated on the entire substrate, or may be applied and / or impregnated on a part of the substrate.
Moreover, it is preferable to dry the aqueous coating composition after coating and / or impregnation. Drying can be performed by a known method such as an oven or hot air. The drying temperature is preferably 50 to 150 ° C, more preferably 80 to 120 ° C.

  The application of the aqueous coating composition of the present invention is not particularly limited, and can be used for, for example, a sealer, a primer, a hard coat for plastic, an anchor coat agent, an ink, a sealant, or an adhesive.

<Composite sheet (1)>
The composite sheet (1) of the present invention is obtained by applying the aqueous coating composition of the present invention to a base sheet composed of an aliphatic polyester resin and / or a plant-derived resin.
Examples of aliphatic polyester resins include polylactic acid, polyethylene succinate, polypropylene succinate, polybutylene succinate, polypentane succinate, polyhexane succinate, and other polysuccinate resins, caprolactone-butylene succinate, polybutylene adipate, Examples include terephthalate, polybutylene succinate adipate modification, polycaprolactone, polybutylene succinate carbonate modification, polyethylene terephthalate succinate, polyethylene succinate, polyhydroxybutyrate and the like.
The most typical plant-derived resin is polylactic acid. The plant-derived resin also includes the above aliphatic polyester-based resin synthesized from plants, for example. In addition to these, cellulose-based and starch-based ones such as cellulose acetate are also included.
These aliphatic polyester-based resins and plant-derived resins can be appropriately selected, and any one of them may be used alone, or a plurality of types may be mixed.
The thickness of the base sheet is not particularly limited, and may be any thickness.

The method of applying or impregnating the aqueous coating composition of the present invention to the substrate sheet is the same as the method of applying and / or impregnating the aqueous coating composition of the present invention to the substrate.
The application amount of the aqueous coating composition is not particularly limited, and may be appropriately set according to the use of the base sheet, the adhesion strength, and the like.

<Composite sheet (2)>
The composite sheet (2) of the present invention is obtained by impregnating or applying the aqueous coating composition of the present invention to a base sheet composed of natural fibers.
Natural fibers include pulp (cotton, seed hair (kapok, pompacs, etc.), bast fibers (flax, cannabis, ramie, jute, kozo, mitsu, kenaf, etc.), monocotyledonous fibers (bamboo, straw, bagasse, Esparto, etc.), wood fibers (eg, wood fibers such as conifers, hardwoods, etc.), leaf fibers (manila hemp, sisal, etc.)) or regenerated pulp, bast fiber, monocot plant fiber, leaf fiber without pulping Examples include plant-derived fibers such as directly obtained fibers. The paper may be waste paper.
These natural fibers can be appropriately selected, and any one of them may be used alone or a mixture of a plurality of types may be used.
As a base material sheet, the nonwoven fabric, paper, etc. which consist of the said natural fiber are mentioned, for example.
The thickness of the base sheet is not particularly limited, and may be any thickness.

The method of applying or impregnating the aqueous coating composition of the present invention to the substrate sheet is the same as the method of applying and / or impregnating the aqueous coating composition of the present invention to the substrate.
The application amount or impregnation amount of the aqueous coating composition is not particularly limited, and may be appropriately set according to the use of the substrate sheet, the adhesion strength, and the like.

<Coating sheet>
The decorative sheet of the present invention has the composite sheet (1) or (2) of the present invention (hereinafter, these may be collectively referred to as a composite sheet).
The composite sheet may constitute the entire decorative sheet or a part thereof.
The makeup of the decorative sheet when the composite sheet of the present invention constitutes a part of the decorative sheet includes various types. For example, the base sheet and the water-based coating on one side or both sides of the base sheet. The structure which has the oxidation polysaccharide content layer formed by apply | coating a composition like anchor coating, and the printing layer provided on this oxidation polysaccharide content layer is mentioned. Moreover, the structure which provided the layer for protecting a printing layer further to this structure is mentioned.
Further, for example, a layer for imparting flexibility, strength, and concealability can be further provided on one side or both sides of the composite sheet. In addition, a decorative sheet produced by using a layer formed using the aqueous coating composition of the present invention as an adhesive layer and laminating another layer on the adhesive layer can also be mentioned.
Moreover, a pigment can be mix | blended with the water-system coating composition of this invention, and a decorative sheet can also be obtained using this as ink.
The use of the decorative sheet is not particularly limited. For example, a housing such as a television, an audio, or a recorder, a surface material of an electrical product such as a refrigerator door, various storage furniture such as a bag, a shelf, or a desk, or a furniture such as a unit furniture. Furniture materials such as furniture doors, interior materials for buildings such as walls, floors and ceilings, exterior walls, roofs, door exteriors, exterior materials for buildings such as window frames, doors, door frames, window frames, edges, widths It can be suitably used for building materials such as wood, opening frames, flooring materials, ceiling materials, vehicle interior materials such as automobiles, trains and ships, stationery, office supplies and the like.

<Coating material>
The decorative material of the present invention is formed by bonding at least the decorative sheet of the present invention to a base material.
As a base material, the thing according to the use of the said decorative material is used. Specific examples include flat plates made of various materials, plate materials such as curved plates, three-dimensional shaped articles, sheets (or films), and the like. Examples of the base material include wood materials such as wood veneer, wood plywood, particle board, and MDF (medium fiber board); metal materials such as iron and aluminum; ceramics such as glass and ceramics Ceramic materials such as non-cement ceramic materials such as plaster, non-ceramic ceramic materials such as ALC (lightweight cellular concrete) plates; polyolefin resins such as acrylic resins, polyester resins, polystyrene resins, polypropylene resins, ABS (acrylonitrile) -Butadiene-styrene copolymer) Resin materials such as resin, phenol resin, vinyl chloride resin, cellulose resin, rubber, etc .; paper such as fine paper, Japanese paper; non-woven fabric made of fibers such as carbon fiber, glass fiber, resin fiber, or the like Woven cloth; a composite material obtained by combining two or more of these may be used.
A base material and a decorative sheet can be bonded via an adhesive agent, for example. Any conventionally known adhesive can be used as the adhesive. Moreover, you may use the water-system coating composition of this invention as an adhesive agent.
There is no restriction | limiting in particular as a use of a decorative material, The thing similar to the use of the said decorative sheet is mentioned.

The water-based coating composition of the present invention has high affinity with natural materials and biodegradable materials, and has good adhesion to substrates made of these substances. Moreover, water resistance is high. Furthermore, since the oxidized polysaccharide used in the aqueous coating composition of the present invention is obtained by oxidizing a polysaccharide that is a natural material, there are few adverse effects on the environment and the human body.
Conventionally, water-soluble polysaccharides such as starch are mainly used for coating natural materials and biodegradable materials. However, according to the present invention, polysaccharides that are hardly soluble in water such as cellulose and chitin are used. Alternatively, it can be oxidized in an aqueous system and used as an aqueous solution or dispersion of an oxidized polysaccharide. For this reason, it is possible to perform a coating process in an aqueous system using various materials.
Furthermore, the coating film formed using the aqueous coating composition of the present invention is also excellent in barrier properties. Therefore, by using the aqueous coating composition of the present invention as a coating agent for a polylactic acid film having a high gas permeability, the migration of various low molecular compounds from the inside and outside of the film is prevented, and the deterioration of the film is suppressed. It is also possible.
Therefore, the composite sheet obtained by using the water-based coating composition of the present invention, the decorative sheet having the composite sheet, and the decorative material having the decorative sheet are friendly to the global environment and the human body without generating toxic gas even when incinerated. It is. It is also excellent in durability and the like.

<Production Example 1>
10 g of corn starch was dispersed in 100 g of water. A solution in which 0.1 g of TEMPO and 2 g of sodium bromide were dissolved in 100 g of water was added, and 100 g of an aqueous sodium hypochlorite solution was added dropwise to initiate the oxidation reaction. The reaction temperature was maintained at 2-5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to maintain the pH at 10.75.
One hour after the start of the reaction, the corn starch in the system was completely dissolved. This is probably because all corn starch was oxidized to oxidized starch.
Then, ethanol was added to the aqueous solution to stop the reaction, and impurities were removed from the aqueous solution using an ultrafiltration device, and at the same time, the oxidized starch was concentrated to prepare 100 ml of an oxidized starch aqueous solution.

<Production Example 2>
In order to replace COONa in the oxidized starch with COOH with respect to the oxidized starch aqueous solution of Production Example 1, 0.1 N hydrochloric acid was added, and ultrafiltration was further performed to prepare 100 ml of an aqueous solution of COOH-type oxidized starch.

<Production Example 3>
10 g of commercially available regenerated cellulose (Benryse manufactured by Asahi Kasei Kogyo Co., Ltd.) was suspended in 300 g of water, a solution prepared by dissolving 0.1 g of TEMPO and 2 g of sodium bromide was added to 100 g of water, and the mixture was cooled to 5 ° C. or lower. 100 g of aqueous sodium hypochlorite solution was added dropwise thereto to start the oxidation reaction. The reaction temperature was maintained at 2-5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was successively added to maintain the pH at 10.75.
Two hours after the start of the reaction, the regenerated cellulose was completely dissolved. This is probably because all of the regenerated cellulose was oxidized.
Then, ethanol is added to the aqueous solution of the water-soluble oxidized regenerated cellulose to stop the reaction. From this aqueous solution, impurities are removed using an ultrafiltration device, and at the same time, the oxidized regenerated cellulose is concentrated to obtain 100 ml of oxidized regenerated cellulose. A cellulose aqueous solution was prepared. When this aqueous solution was filtered using a 5 μm membrane filter, the insoluble residue was 1% or less.

<Production Example 4>
10 g of commercially available chitin (Dainippon Seika Chitin P) was immersed in 200 g of a 45% aqueous sodium hydroxide solution and sufficiently infiltrated, and then diluted with 700 g of ice. When the ice and chitin were dissolved, hydrochloric acid was added to neutralize the system, and chitin was precipitated again. After thoroughly washing with water, a slurry having a solid content of 2% was obtained. TEMPO 0.1g and sodium bromide 2g were added to this, and it cooled to 5 degrees C or less. 100 g of aqueous sodium hypochlorite solution was added dropwise thereto to start the oxidation reaction. The reaction temperature was maintained at 2-5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75.
Two hours after the start of the reaction, chitin was completely dissolved. This is probably because all chitin was oxidized.
Then, ethanol is added to the aqueous solution of water-soluble chitin oxide to stop the reaction, and impurities are removed from the aqueous solution using an ultrafiltration device, and at the same time, the chitin oxide is concentrated, and 100 ml of the aqueous solution of chitin oxide is obtained. Was prepared.

<Production Example 5>
10 g of commercially available chitin (Dainippon Seiki Chitin P) was suspended in 400 g of water as it was. TEMPO 0.1g and sodium bromide 2g were added and it cooled to 5 degrees C or less. 60 g of aqueous sodium hypochlorite solution was added dropwise thereto to start the oxidation reaction. The reaction temperature was maintained at 2-5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75.
Two hours after the start of the reaction, ethanol was added to stop the reaction, and the mixture was washed with a mixed solution of water and ethanol, and finally washed with acetone to obtain 12 g of chitin oxide powder.

<Examples 1-5>
The aqueous solution of oxidized polysaccharide prepared in Production Examples 1 to 4 and the aqueous suspension prepared to have a concentration of 10% of the oxidized polysaccharide powder prepared in Production Example 5 were each made of Takenate WD-725 ( Mitsui Chemicals Polyurethane Co., Ltd.) was added in the proportions shown in Table 1 to obtain aqueous coating compositions of Examples 1-5.
In the obtained aqueous coating compositions of Examples 1 to 5, the ratio (%) of “the number of reactive functional groups (isocyanate groups) in the polyfunctional compound” to “the number of reactive groups in the oxidized polysaccharide” Table 1 shows.

<Examples 6 to 10>
Polycarbodiimide V-02 for the aqueous solution of oxidized polysaccharide prepared in Production Examples 1 to 4 and the aqueous suspension prepared so that the oxidized polysaccharide powder prepared in Production Example 5 had a concentration of 10%, respectively. (Nisshinbo Co., Ltd.) and Takenate WD-725 (Mitsui Chemicals Polyurethane Co., Ltd.) were added in the same amount and in the proportions shown in Table 1, and the aqueous coating compositions of Examples 6 to 10 were added. Obtained.
In the obtained aqueous coating compositions of Examples 6 to 10, the ratio of “the number of reactive functional groups (carbodiimide group and isocyanate group) in the polyfunctional compound” to “the number of reactive groups in the oxidized polysaccharide” ( %) Is shown in Table 1.

<Example 11>
After applying the aqueous coating composition of Example 6 on one side of a polylactic acid substrate having a thickness of 80 μm so as to have a film thickness of 0.1 μm, the biotech color HGP ink (large size) was formed on the formed coating film. Nissei Kagaku Kogyo Co., Ltd.) was applied to a thickness of 5 μm to obtain a composite sheet of Example 11.

<Comparative Example 1>
Example in which Biotech Color HGP ink (manufactured by Dainichi Seika Kogyo Co., Ltd.) was applied to a thickness of 5 μm directly on a polylactic acid substrate without applying the aqueous coating composition of Example 6 In the same manner as in Example 11, a composite sheet of Comparative Example 1 was obtained.

The composite sheet obtained in Example 11 and Comparative Example 1 was evaluated as follows.
(Adhesion evaluation 1)
About the composite sheet of Example 11 and Comparative Example 1, in accordance with JIS K5400, 10 × 10 grids (1 mm distance, 100 cuts in total) in the vertical and horizontal directions on the biotech color HGP black coating surface The cellophane (registered trademark) was affixed thereon and a peel test was conducted.
Table 2 shows the number of grids remaining without peeling on the surface of the composite sheet after peeling.

(Water resistance evaluation 1)
The surface of the coating film was rubbed 20 times with a cotton swab soaked in water, and the properties of the coating film were observed. The results are shown in Table 2.

<Example 12>
The water-based coating composition of Example 2 was applied to one side of a 35 μm-thick biaxially stretched polylactic acid base material with a bar coater so that the coating amount was 3.5 g / m ^2, and then in an oven at 80 degrees. The composite sheet was obtained by drying for 2 minutes. In the same manner, another composite sheet was prepared, and then the surfaces of these two laminated sheets coated with the aqueous coating composition were brought into contact with each other and pasted with a 60 ° C. heat roller to obtain the composite sheet of Example 12. It was.

Moreover, the following evaluation was performed about this composite sheet.
(Adhesion evaluation 2)
The composite sheet of Example 12 was cut into a strip having a width of 25 mm, and a T-type peel test was performed at a peel rate of 50 mm / min.
As a result, in each of the strips, the polylactic acid base material is broken, and the coating film formed using the aqueous coating composition of Example 2 has sufficient adhesion to the polylactic acid base material. all right.

<Example 13>
Thick paper with a basis weight of 100 g / m ² was impregnated with the aqueous coating composition of Example 4 for 1 minute and compressed with a hot press at 80 ° C. to obtain a composite sheet of Example 13.

<Comparative example 2>
A composite sheet of Comparative Example 2 was obtained in the same manner as in Example 13, except that an unoxidized starch aqueous solution was used instead of the aqueous coating composition of Example 4.

The composite sheet obtained in Example 13 and Comparative Example 2 was evaluated as follows.
(Water resistance evaluation 2)
The composite sheets of Example 13 and Comparative Example 2 were cut into strips having a width of 10 mm, respectively, and a tensile test in a dry state and a tensile test after immersing in water for 1 hour were performed according to JIS P8113.
The ratio (wet / dry) of the breaking strength (wet paper strength) in the wet state to the breaking strength (dry paper strength) in the dry state was determined by the following formula, and the water resistance was evaluated. It shows that water resistance is so high that this wet / dry is large. The results are shown in Table 3.
wet / dry (%) = (wet paper strength / dry paper strength) × 100

<Example 14>
After applying the aqueous coating composition of Example 8 to a polylactic acid substrate having a film thickness of 80 μm so as to have a film thickness of 0.2 μm, a pattern layer is further formed on the formed coating film with a modified starch-based ink. Printing was performed, and a two-component curable acrylic urethane resin was applied to the thickness of 6 g / m ² (dry) to obtain a decorative sheet of Example 14.

  As is apparent from the above results, the aqueous coating composition of the present invention can be applied or impregnated with an aqueous system using a component derived from a polysaccharide that is a natural material. In addition, because it uses an oxidized polysaccharide and a polyfunctional compound in combination, it forms a coating film with high water resistance and good adhesion to natural and biodegradable materials such as polylactic acid and paper. It is possible.

Claims (8)

  An aqueous coating composition comprising an aqueous solution or an aqueous dispersion containing an oxidized polysaccharide obtained by oxidizing a polysaccharide and a compound having two or more reactive functional groups in one molecule.   The aqueous coating composition according to claim 1, wherein the polysaccharide is at least one selected from the group consisting of starch, cellulose, chitin, and chitosan.   The aqueous coating composition according to claim 1 or 2, wherein the reactive functional group is at least one selected from the group consisting of an isocyanate group, a blocked isocyanate group, an epoxy group, a carbodiimide group, an oxazoline group, and an amino group.   The water-based coating composition as described in any one of Claims 1-3 used for a sealer, a primer, the hard coat for plastics, an anchor coating agent, ink, a sealing agent, or an adhesive agent.   The composite sheet formed by apply | coating the water-system coating composition as described in any one of Claims 1-4 to the base material sheet comprised from aliphatic polyester-type resin and / or plant origin resin.   The composite sheet formed by apply | coating and / or impregnating the water-system coating composition as described in any one of Claims 1-4 to the base material sheet comprised from a natural fiber.   A decorative sheet comprising the composite sheet according to claim 5.   A cosmetic material comprising at least the decorative sheet according to claim 7 bonded to a base material.