JP2016155343A - Laminate, thermosensitive recording medium and inkjet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate capable of suppressing yellowing without addition of an additive to a crosslinked product layer formed of a modified PVA resin and a crosslinking agent and without requiring irradiation with active energy rays regardless of kinds of the modified PVA resins.SOLUTION: A laminate has: paper(A); a crosslinked product layer (B) obtained by reaction of a modified group-containing polyvinyl alcohol-based resin (b1) having an active hydrogen and a crosslinking agent (b2); and a resin layer (C). An amount (L) of a component on a long-time side and an amount (S) of a component on a short-time side inH nuclear spin-spin relaxation time (T) in the resin layer (C) satisfy the following expression (1).SELECTED DRAWING: None

Description

  The present invention relates to a laminate having a crosslinked product layer containing a crosslinked product of paper and a polyvinyl alcohol-based resin containing a modified group having active hydrogen, and more particularly relates to a laminate having less yellowing of the crosslinked product layer. Is.

  Conventionally, a coating solution in which a resin such as polyvinyl alcohol resin (hereinafter, polyvinyl alcohol is sometimes abbreviated as PVA) is dissolved in a liquid component such as water is applied to paper and dried to make the paper water resistant. And imparting oil resistance and oil resistance. The laminated body in which the coating film is formed on the paper as described above has been used for various purposes in recent years, such as being used for a wrapping paper and a ticket, and as a glossy paper for photographic printing.

  The PVA resin used for the coating liquid is excellent in oil resistance and solvent resistance, and thus is used for various applications. Among them, a modified group-containing PVA resin having active hydrogen capable of imparting water resistance by reacting with a crosslinking agent to form a crosslinked product (hereinafter referred to as a modified group-containing PVA resin having active hydrogen is modified PVA resin). Are widely used.)

However, there has been a problem that the modified PVA resin reacts with the crosslinking agent and turns yellow when it becomes a crosslinked product.
Various studies have been conducted on such problems in the past. For example, an acetoacetyl group-containing polyvinyl alcohol resin (hereinafter sometimes abbreviated as AA-modified PVA resin) is used as a modified PVA resin. It has been proposed to use a reducing agent such as sodium bisulfite in a crosslinked product using a hydrazine compound as a crosslinking agent (see, for example, Patent Document 1).
In addition, it is also proposed to suppress discoloration by irradiating a cross-linked product of an AA-PVA-based resin and glyoxylate with ultraviolet rays (see, for example, Patent Document 2).
In addition, in order to prevent yellowing of diacetone acrylamide-modified polyvinyl alcohol-based resin (hereinafter sometimes abbreviated as DA-PVA-based resin), a method for producing an ink jet recording medium in which a crosslinking agent is blended immediately before coating. Has been proposed (see, for example, Patent Document 3).

JP 2009-280754 A JP2013-028697A JP 2006-281474 A

However, the technique of Patent Document 1 has a problem in that the original physical properties of the AA-PVA-based resin may be reduced by adding a reducing agent. Moreover, in the technique of patent document 2, since there exists a possibility that another compound may raise | generate reaction by irradiating an ultraviolet-ray, the use which can be used was restricted.
Furthermore, although the technique of Patent Document 3 is effective for the DA-PVA-based resin, it is not effective for the AA-PVA-based resin.
Therefore, the present invention is based on such a background, without adding an additive to the cross-linked product layer composed of the modified PVA-based resin and the cross-linking agent, and without requiring irradiation with active energy rays, and the modified species of the modified PVA-based resin. Regardless, the object is to provide a laminate that can suppress yellowing.

  However, as a result of intensive studies in view of the above circumstances, the present inventors contain a cross-linked product layer (B) containing a cross-linked product of paper (A), modified PVA resin (b1) and cross-linking agent (b2). In the laminated body which carries out, it discovered that yellowing could be suppressed by providing one more resin layer (C) which has a specific relaxation time, and completed this invention.

That is, the gist of the present invention is a laminate having paper (A), a crosslinked product layer (B) obtained by reacting a modified PVA resin and a crosslinking agent, and a resin layer (C),
In the ¹ H nucleus spin-spin relaxation time (T _2H ) of the resin layer (C), the long-term component amount (L _T2H ) and the short-term component amount (S _T2H ) satisfy the following formula (1). It is related with the laminated body characterized by this.

  The present invention also provides a heat-sensitive recording medium using the laminate and an ink jet recording medium.

  In the present invention, by using a resin layer having a long relaxation time on the long side, the transition of the metal from the paper, which is one of the causes of yellowing of the crosslinked layer, that is, the metal present in the paper is It is presumed that the transfer to the cross-linked product layer could be prevented and yellowing could be suppressed.

  The laminate of the present invention can suppress yellowing of the cross-linked product layer. For example, it becomes a laminate excellent in appearance such as printing paper and wrapping paper.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
Hereinafter, the present invention will be described in detail.

  The laminate of the present invention comprises a paper (A), a crosslinked product layer (B) containing a crosslinked product obtained by reacting the modified PVA resin (b1) with a crosslinking agent (b2), and a specific resin layer ( C).

  First, each layer will be described. In addition, in this invention, the layer in a crosslinked material layer (B) or a resin layer (C) means the film | membrane which has the continuous surface, and also includes the coating film formed by coating In addition, this includes a state in which the coating film partially enters a substrate such as paper.

[Paper (A)]
Paper (A) is usually printed on paper such as manila balls, white balls, liners, general high-quality paper, medium-quality paper, gravure paper, upper / middle / lower grade paper, newsprint paper, release paper, carbon paper, non-paper Examples include carbon paper, glassine paper, and exposed kraft paper. Of these, general fine paper is preferable in terms of paper strength, strength, and opacity.

[Crosslinked product layer (B)]
The crosslinked product layer (B) contains a crosslinked product obtained by reacting the modified PVA resin (b1) with the crosslinking agent (b2). The modified PVA resin (b1) and the crosslinking agent (b2) Will be described in order.

[Modified PVA resin (b1)]
The modified PVA resin (b1) used in the present invention is a PVA resin having a modifying group such as ketone, carboxylic acid or carboxylic acid ester having active hydrogen, and specifically includes, for example, an acetoacetyl group or a diacetone group. PVA-type resin which has. Of these, AA-PVA-based resin (b1-1) and DA-PVA-based resin (b1-2) are preferable, and AA-PVA-based resin (b1-1) is more preferable.

The average degree of polymerization of the modified PVA resin (b1) is usually 300 to 4000, particularly preferably 400 to 3000, and more preferably 800 to 2000. If the average degree of polymerization is too small, sufficient water resistance may not be obtained, or a sufficient crosslinking rate may not be obtained. On the other hand, if the average degree of polymerization is too large, the viscosity of the coating solution becomes too high, resulting in a substrate. Coating tends to be difficult.
The degree of saponification of the modified PVA resin (b1) is usually 80 to 100 mol%, more preferably 85 to 99.9 mol%, particularly 90 to 99.8 mol%. If the degree of saponification is too low, it tends to be difficult to obtain an aqueous solution, the stability of the aqueous solution decreases, and the water resistance of the resulting crosslinked polymer tends to decrease.
The modified amount of the modified PVA resin (b1) is usually 0.1 to 20 mol%, more preferably 1 to 15 mol%, and particularly preferably 2 to 10 mol%. If the content is too small, the water resistance tends to decrease or a sufficient crosslinking rate cannot be obtained. Conversely, if the content is too large, the water solubility tends to decrease or the stability of the aqueous solution tends to decrease. .

[AA-modified PVA resin (b1-1)]
Next, the AA-PVA-based resin (b1-1) used in the present invention will be described.
The AA-PVA-based resin (b1-1) used in the present invention has an acetoacetyl group (AA group) bonded to the main chain of the PVA-based resin directly or through an oxygen atom or a linking group. Polyvinyl alcohol-type resin containing the structural unit which has AA group represented by Formula (1) is mentioned. In addition, this AA-ized PVA-type resin (b1-1) has a vinyl alcohol structural unit other than the structural unit which has AA group, and also has the vinyl ester structural unit of an unsaponified part.

  Examples of the vinyl ester compounds include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, Examples thereof include vinyl stearate, vinyl benzoate, vinyl versatate, and vinyl acetate is preferably used from the viewpoint of economy.

  Further, a saponified product of a copolymer of a vinyl ester compound and a copolymerizable compound can be used. Examples of the copolymerizable compound include ethylene, propylene, isobutylene, α-octene, α-dodecene, Olefins such as α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, and 3,4-dihydroxy-1-butene And derivatives thereof, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid, salts, monoesters or dialkyl esters thereof; acrylonitrile, methacrylonitrile, etc. Nitriles of diacetone acrylamide, acrylamide, methacrylate Amides such as amides; Olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof; alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2, Vinyl compounds such as 2-dialkyl-4-vinyl-1,3-dioxolane and glycerol monoallyl ether; substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate; vinylidene chloride, 1,4-diacetoxy-2 -Butene, 1,4-dihydroxy-2-butene, vinylene carbonate and the like.

  The amount of the copolymerizable compound to be introduced varies depending on the type of the compound and cannot be generally specified, but is usually 10 mol% or less, particularly 5 mol% or less of the total structural unit. This is not preferable because it may be damaged or the compatibility with the crosslinking agent may be reduced.

  The average degree of polymerization (based on JIS K6726) of the AA-PVA-based resin (b1-1) may be appropriately selected depending on the application, but is usually 300 to 4000, particularly 400 to 3000, and further 800 to 2000. Are preferably used. If the average degree of polymerization is too small, sufficient water resistance may not be obtained, or a sufficient crosslinking rate may not be obtained. On the other hand, if the average degree of polymerization is too large, the viscosity of the coating solution becomes too high, resulting in a substrate. Coating tends to be difficult.

  The saponification degree of the AA-PVA-based resin (b1-1) is usually 80 to 100 mol%, more preferably 85 to 99.9 mol%, particularly 90 to 99.8 mol%, In this case, 95 to 99.8 mol% is preferably used. If the degree of saponification is too low, it tends to be difficult to obtain an aqueous solution, the stability of the aqueous solution decreases, and the water resistance of the resulting crosslinked polymer tends to decrease.

  Moreover, AA group content (Hereinafter, it may be abbreviated as AA conversion degree.) In AA-ized PVA-type resin (b1-1) is 0.1-20 mol% normally, Furthermore, 1- It is preferably 15 mol%, particularly 3 to 10 mol%. If the content is too small, the water resistance tends to decrease or a sufficient crosslinking rate cannot be obtained. Conversely, if the content is too large, the water solubility tends to decrease or the stability of the aqueous solution tends to decrease. .

In the present invention, it is preferable that all of the PVA resins used are AA-PVA resins (b1-1), but PVA resins other than the AA-PVA resins (b1-1) are used in combination. The content thereof is usually 20% by weight or less, particularly preferably 10% by weight or less, more preferably 5% by weight or less based on the AA-PVA-based resin (b1-1).
As PVA resins other than the AA-modified PVA resin (b1-1), various modified PVAs obtained by copolymerizing unmodified PVA resins and various monomers having a copolymerizable property with vinyl ester monomers. Based resins.

  The AA-PVA-based resin (b1-1) used in the present invention includes an alkali metal acetate such as sodium acetate used or produced as a by-product in the production process (mainly alkali metal hydroxide used as a saponification catalyst). Derived from the reaction product of the product with acetic acid produced by saponification of polyvinyl acetate), organic acid such as acetic acid (when the acetoacetate group is introduced into the PVA resin, it is occluded in PVA during the reaction with diketene A portion of the organic solvent (derived from the reaction solvent of the PVA resin, the cleaning solvent during the production of the AA-PVA resin, etc.) such as methanol and methyl acetate may remain.

  The AA-PVA-based resin (b1-1) can be produced according to the method described in paragraphs [0059] to [0065] of JP-A 2010-077385.

{DA conversion PVA resin (b1-2)}
As modified PVA (b1) used by this invention, DA conversion PVA type-resin (b1-2) can also be used.
Hereinafter, the DA PVA resin (b1-2) will be described in detail.

  The DAized PVA resin (b1-2) used in the present invention is a PVA resin in which a diacetone acrylamide structural unit is introduced. In order to obtain the DAized PVA resin (b1-2), a vinyl ester A method of saponifying a copolymer of a monomer based on diacetone acrylamide is preferably used. In addition, this DA conversion PVA-type resin (b1-2) has a vinyl alcohol structural unit other than a diacetone acrylamide structural unit, and also an unsaponified vinyl ester structural unit.

  The average degree of polymerization (based on JIS K6726) of the DA PVA resin (b1-2) thus obtained is preferably 300 to 4000, more preferably 400 to 3500, and particularly preferably 500 to 3000, and the average degree of polymerization is too small. And, there is a tendency that sufficient water resistance cannot be obtained or sufficient crosslinking rate cannot be obtained, and conversely, if it is too large, the viscosity of the aqueous solution becomes too high, and it is applied to the base material and various processes. It tends to be difficult to apply.

  Further, the degree of saponification of the DA-modified PVA resin (b1-2) is 80 to 100 mol%, preferably 85 to 99.9 mol%, particularly 90 to 99.8 mol%, especially 95-99.8 mol%. If the degree of saponification is too low, the water solubility tends to decrease.

  The content of the diacetone acrylamide structural unit in the DA PVA resin (b1-2) is 0.1 to 20 mol%, further 0.2 to 15 mol%, particularly 0.3 to 10 mol. If the content is too small, sufficient water resistance may not be obtained, or a sufficient crosslinking rate may not be obtained. Conversely, if the content is too large, water solubility may be reduced, There is a tendency for the stability of the aqueous solution to decrease.

  Moreover, the DA conversion PVA resin (b1-2) used in the present invention is obtained by copolymerizing a vinyl ester monomer or a monomer copolymerizable with diacetone acrylamide within a range not inhibiting the effects of the present invention. Also good.

  As a method for producing such a DA-PVA-based resin (b1-2), it can be produced according to the method described in paragraphs [0032] to [0035] of JP-A-2007-254732.

{Crosslinking agent (b2)}
The modified PVA resin (b1) needs to react with a crosslinking agent (b2) to improve water resistance, and the crosslinking agent (b2) is generally used for, for example, a PVA resin. Aldehyde compounds such as glyoxal, organic salts of hydrazine, hydrazine compounds such as adipic acid dihydrazide, metal salts of glyoxylic acid, methylol compounds such as methylolated melamine, metal compounds such as basic zirconium chloride, etc., preferably reaction rate From this point, adipic acid dihydrazide is used.

The cross-linked product layer (B) in the present invention is prepared, for example, by using the modified PVA resin (b1) as an aqueous solution and blending the cross-linking agent (b2) and various additives to prepare a cross-linked product coating solution. And it is obtained by forming this as a coating film.
In such a cross-linked product coating solution, the content of the cross-linking agent (b2) is usually 0.5 to 30 wt. Parts, preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight.
If the content of the crosslinking agent (b2) is too much or too little, the water resistance tends to decrease.
In addition, the content of the modified PVA resin (b1) with respect to the entire coating liquid is usually 1 to 50% by weight, preferably 2 to 30% by weight. There is a tendency that the effect as the layer (B), that is, water resistance cannot be sufficiently exhibited. Conversely, when the amount is too large, the viscosity of the coating liquid becomes high, so that coating tends to be difficult.

  Moreover, as pH of the coating liquid for crosslinked material layers, 10 or less are preferable, and also it is 3-10. When pH is too high, there exists a tendency for warm water resistance and plasticizer resistance to fall. In addition, since AA-PVA-based resin (b1-1) becomes weakly acidic when made into an aqueous solution, such pH adjustment is usually not necessary in many cases. However, if necessary, an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or citric acid can be used. The pH may be adjusted with an organic acid such as acid, tartaric acid, succinic acid, or acetic acid, or a basic compound such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, or ammonia.

Furthermore, an inorganic filler, a thermoplastic resin, a pigment, other additives, etc. can also be mix | blended with the coating liquid for crosslinked material layers as needed.
Examples of the inorganic filler include kaolin, silica, calcium hydroxide, calcium carbonate, and aluminum hydroxide.

Examples of the thermoplastic resin include acrylic resins, polyester resins, polyvinyl chloride resins, saponified ethylene-vinyl acetate copolymers, and acrylic resins are preferred from the viewpoint of ink adhesion.
The blending amount of the thermoplastic resin is usually 10 to 70% by weight, preferably 20 to 60% by weight, based on the total solid content of the coating liquid.

  Examples of the pigment include organic pigments such as nylon resin filler, urea / formalin resin filler, and starch particles. Examples of other additives include lubricants such as zinc stearate, calcium stearate, and paraffin wax, and interfaces. Activators, ultraviolet absorbers, fluorescent dyes, release agents, antioxidants and the like can be mentioned.

Moreover, the following orders are mentioned for the compounding order of each component, for example.
(A) Method of blending one component at a time (a) Method of blending any two to three components and then blending the remaining components sequentially or collectively (c) Method of blending all components simultaneously (D) ) A method of blending the crosslinking agent (b2) last in accordance with the speed of the crosslinking reaction.

Moreover, as a coating method of the coating liquid for bridge | crosslinking material layers, a roll coater method, an airy doctor method, a blade coater method, a bar coater method, a size press method, a gate roll method, a curtain coater method etc. are mentioned, for example.
Moreover, as drying conditions after apply | coating the coating liquid for crosslinked material layers, 5-150 degreeC normally, Furthermore, 30-120 degreeC, Especially the temperature conditions of 50-100 degreeC are preferable. A drying time of 1 to 60 minutes, further 0.1 to 30 minutes, particularly 0.2 to 10 minutes is preferably used.
The thickness of the cross-linked product layer (B) is usually 0.01 to 100 μm, preferably 0.05 to 20 μm, particularly preferably 0.1 to 10 μm after drying, and if it is too thin, the water resistance decreases. If it is too thick, it takes time to dry and the productivity tends to decrease.

[Resin layer (C)]
In the resin layer (C) of the present invention, the long-term component amount (L _T2H ) and the short-term component amount (S _T2H ) in the ¹ H nuclear spin-spin relaxation time (T _2H ) It is characterized by satisfying 1).

Above formula (1), the proportion of the components of the long-time side (L _T2H) and ingredient amounts short side components of the long-time side to the sum of (S _T2H) (L _T2H) is 30% or more This ratio is more preferably 35% or more, and still more preferably 40% or more. There is no particular upper limit for this ratio, but it is actually about 80%.

τ：時間、 Ｍ（τ）：τ（μｓ）後に観測される磁化
Ｍ（０）_S：０ｓにおける短時間側の磁化
Ｍ（０）_L：０ｓにおける長時間側の磁化
Ｔ_2S：短時間側の緩和時間（μｓ）
Ｔ_2L：長時間側の緩和時間（μｓ）
なお、今回の¹Ｈ核スピン−スピン緩和時間（Ｔ_2H）における、長時間側の成分量（Ｌ_T2H）と短時間側の成分量（Ｓ_T2H）は下記のように定義し、算出する。
（全体の成分）Ｌ_T2H＋Ｓ_T2H＝１
長時間側の成分量（Ｌ_T2H）＝（Ｍ（０）_L）/（Ｍ（０）_S＋Ｍ（０）_L）
短時間側の成分量（Ｓ_T2H）＝（Ｍ（０）_S）/（Ｍ（０）_S＋Ｍ（０）_L） Hereinafter, a method for calculating the relaxation time will be described in more detail.
[1] Fabrication of coating The resin used for the resin layer (C) is a 10% by weight aqueous solution, and this aqueous solution is coated on a polyethylene terephthalate (PET) film by a pool method, and then at 23 ° C. and 50% RH for 3 days. Dry to produce a cast film having a thickness of 100 μm.
[2] Measurement of relaxation time (NMR measurement)
The NMR measurement model is “Bruker AVANCEIII 400WB”, and the probe uses a 4 mm CP / MAS probe. As a measuring method, 100 mg of the pulverized film obtained above is put into a rotor having a diameter of 4 mm, and measurement is performed by the solid echo method. Further, the number of rotations of the rotor was 0 Hz, and the measurement parameter was ¹ H90 ^o pulse with an intensity of 1.9 μs × −2.6 dB (141 W / 300 W). The echo delay is set to 5 μs, the FID signal capture time is set to 4.1 ms, the number of integrations is set to 1, the observation center is set to 0 ppm, the observation width is set to 4996 ppm, and the measurement time is set to 4 seconds.
The relaxation time thus obtained is curve-fitted into equation (2) to calculate the long-time component and the short-time component.

τ: time, M (τ): magnetization observed after τ (μs) M (0) _S : magnetization on the short time side at 0 s M (0) _L : magnetization on the long time side at 0 s T _2S : short time side Relaxation time (μs)
T _2L : Long time relaxation time (μs)
Note that the component amount on the long side (L _T2H ) and the component amount on the short side (S _T2H ) in the current ¹ H nuclear spin-spin relaxation time (T _2H ) are defined and calculated as follows.
(Whole components) L _T2H + S _T2H = 1
Long-term component amount (L _T2H ) = (M (0) _L ) / (M (0) _S + M (0) _L )
Short-term component amount (S _T2H ) = (M (0) _S ) / (M (0) _S + M (0) _L )

  The resin constituting the resin layer (C) in the present invention is not particularly limited as long as it satisfies the above formula (1), and examples thereof include polyester resins and acrylic resins. In this respect, water-soluble polyester resins and acrylic resin emulsions may be mentioned, and water-soluble polyester resins are particularly preferable.

Such a water-soluble polyester resin will be described.
Such a water-soluble polyester resin includes a component (iii) having a hydrophilic group such as a sulfonic acid group or a carboxyl group in addition to a polyester resin obtained by copolymerization of a dicarboxylic acid component (i) and a diol component (ii). It is obtained by introducing. Among them, it is preferable to introduce a carboxyl group-containing component.
First, the dicarboxylic acid component (i), the diol component (ii), and the component (iii) having a hydrophilic group will be sequentially described.

  Examples of the dicarboxylic acid component (i) include methyl succinic acid, ethyl succinic acid, 2,2-dimethyl adipic acid, 2,3-dimethyl adipic acid, 2,4-dimethyl adipic acid, 3,3-dimethyl adipic acid, etc. Dicarboxylic acids having a hydrocarbon group in the chain; terephthalic acid, 1,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, octadecanedicarboxylic acid Examples thereof include saturated dicarboxylic acids such as acids; dicarboxylic acids containing no hydrocarbon group in the side chain, such as fumaric acid, maleic acid, itaconic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, and hexahydrophthalic acid. Of these, dicarboxylic acids containing no hydrocarbon group in the side chain are preferred, and terephthalic acid and isophthalic acid are more preferred.

Examples of the diol component (ii) include neopentyl glycol, 2-methyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3- Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-2, Hydrocarbons in the side chain such as 4-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol Diol containing a group; ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pe Butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, diols containing no hydrocarbon groups in the side chains such as 1,10-decane diol.
Also, a diol having a repeating unit such as a polyester diol, a polyether diol, a polycaprolactone diol, or a polycarbonate diol can be used.
Among these, ethylene glycol, diethylene glycol, and neopentyl glycol are preferable.

Moreover, in order to increase the mechanical strength of the obtained polyester resin or to improve heat resistance, a tri- or higher functional polyol component can be used as the hydroxyl group-containing component.
Examples of the trihydric or higher polyhydric alcohol component include glycerin, trimethylolpropane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, pentaerythritol, diester. Examples include aliphatic polyhydric alcohols such as pentaerythritol.

Examples of the hydrophilic group of component (iii) having a hydrophilic group include a sulfonic acid group and a carboxyl group. The polyester-based resin having a sulfonic acid group can be produced, for example, by the method described in JP-A-63-033419.
Moreover, the polyester-type resin which has a carboxyl group can be manufactured by the method of Unexamined-Japanese-Patent No. 62-240318, for example.
A polyester-based resin having a carboxyl group is preferable in that the effect of the present invention is easily obtained.

Hereinafter, the polyester resin having a carboxyl group will be described.
The number average molecular weight of the polyester-based resin having a carboxyl group used in the present invention is usually 1000 to 20000, preferably 2000 to 15000, and particularly preferably 3000 to 10,000.
Moreover, Tg (glass transition temperature) is 30-100 degreeC normally, Preferably it is 40-90 degreeC, Most preferably, it is 50-80 degreeC. If the Tg is too high, the coating film after drying tends to be hard and tends to crack, and if it is too low, tack tends to remain on the surface of the coating film.
An acid value is 10-200 mgKOH / g normally, Preferably it is 20-150 mgKOH / g, Most preferably, it is 70-120 mgKOH / g. If the acid value is too small, the effects of the present invention tend not to be obtained. If the acid value is too high, repelling may occur during coating or the water resistance tends to decrease.
Furthermore, a hydroxyl value is 5-60 mgKOH / g normally, Preferably it is 10-30 mgKOH / g. If the hydroxyl group is too small, the water solubility tends to decrease. If the hydroxyl group is too high, the number average molecular weight tends to be small, and the coatability tends to decrease.

  The water-soluble polyester-based resin satisfying the above formula (1) of the present invention can be obtained by adjusting the acid value, the hydroxyl value, and the like to the above ranges.

The resin layer (C) in the present invention is prepared by preparing a resin layer coating solution using a resin capable of satisfying the above formula (1) as an aqueous solution or aqueous dispersion, and applying and drying the coating solution. Is obtained.
In addition to the polyester-based resin, other thermoplastic resins, water-soluble polymers, pigments, fillers, and the like can also be blended in the resin layer coating solution.
The solid content concentration of the resin layer coating liquid is usually 1 to 80% by weight, preferably 3 to 60% by weight, and particularly preferably 5 to 50% by weight. When the content is too small, drying tends to take time, and when the content is too large, the coatability tends to decrease.

  Examples of the coating method for the resin layer coating liquid include a roll coater method, an airy tractor method, a blade coater method, a bar coater method, a size press method, a gate roll method, and a curtain coater method. Moreover, as drying conditions after coating the resin layer coating solution, the temperature is usually 5 to 150 ° C., more preferably 30 to 120 ° C., particularly 40 to 100 ° C., and 0.1 to 60 minutes. Further, a drying time of 0.1 to 30 minutes, particularly 0.2 to 20 minutes is preferably used.

  The thickness of the resin layer (C) obtained by applying the above resin layer coating solution is usually 0.01 to 100 μm, preferably 0.05 to 50 μm, particularly preferably 0.1 to 30 μm. If it is too thin, the water resistance tends to decrease, and if it is too thick, the color developability of the thermosensitive recording layer tends to decrease.

[Laminate]
The laminated body of this invention has paper (A), a crosslinked material layer (B), and a resin layer (C).
The place where the resin layer (C) is provided may be a layer that is in contact with paper or a layer that is not in contact with paper, but a layer that is in contact with paper is preferred in that the influence on the physical properties of other layers is small. Further, only one layer or two or more layers may be provided, but only one layer is preferable from the viewpoint of cost and productivity. Furthermore, although a layer may be provided between the paper (A) and the cross-linked product layer (B) or on the opposite side of the cross-linked product layer (B), the paper ( It is more preferable to provide a layer between A) and a crosslinked material layer (B).
The laminate of the present invention is used for applications such as wrapping paper, labels, various tickets, and lotteries.

  Further, by providing other layers in the laminate of the present invention or adding additives to each layer, it can be used for thermal recording media, ink jet recording paper, release paper, release paper, oil resistant paper, water resistant paper, and the like. .

[Thermal recording medium]
The case where the laminate of the present invention is used as a thermal recording medium will be described.
When used as a heat-sensitive recording medium, a heat-sensitive recording layer may be provided between the paper (A) and the cross-linked product layer (B), and the position of the resin layer (C) may be in contact with the paper (A). It may be between the heat-sensitive recording layer and the cross-linked product layer (B). From the viewpoint of protecting the heat-sensitive recording layer, the heat-sensitive recording layer is preferably provided between the resin layer (C) and the crosslinked product layer (B). That is, it is preferable to laminate in the order of paper (A) / resin layer (C) / thermosensitive recording layer / crosslinked product layer (B).
The thermosensitive recording layer will be described below.

{Thermosensitive recording layer}
The heat-sensitive recording layer is obtained by obtaining an aqueous solution (color developing solution) obtained by further blending a color developing substance and a developer with a binder (for example, PVA resin, methyl cellulose, carboxymethyl cellulose, starches, latex, etc.). It can be formed by coating on a substrate such as paper.
At this time, the color-developing substance and the developer are blocked in an aqueous solution, so that they are pulverized to about 0.1 to 5 μm by a side grinder, ball mill, viscomill or the like.

[Inkjet recording medium]
The laminate of the present invention can also be used as an ink jet recording medium. When used as an ink jet recording medium, the crosslinked product layer (B) can be used as an ink receiving layer by containing an inorganic filler in the crosslinked product layer (B). Further, a known gloss layer may be coated on the ink receiving layer.

  Furthermore, in the ink receiving layer using the crosslinked layer (B) in the present invention, a pigment dispersant, a thickener, a fluidity improver, a surfactant, a reducing agent, You may mix | blend an antifoamer, a mold release agent, a penetrating agent, dye, a pigment, a ultraviolet absorber, antioxidant, antiseptic | preservative, a paper strength enhancer, etc.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis.

Example 1
[Measurement of relaxation time]
As resin of the resin layer (C), carboxyl group-containing polyester resin 1 (“Polyester W-0030” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., molecular weight 7000, Tg 75 ° C., hydroxyl value 17 mgKOH / g, acid value 100 mgKOH / g) Using the method described in paragraph [0047], the value of formula (1) was calculated to be 44.6.

[Preparation of laminate 1]
{Preparation of laminate of paper (A) and resin layer (C)}
A 20% aqueous solution of the above polyester-based resin 1 is applied onto a copy paper (quality paper) with an applicator having a clearance of 100 μm, and dried at 70 ° C. for 5 minutes, and the paper (A) and the resin layer (C) A laminate was obtained.

{Preparation of AA-modified PVA resin (b1-1)}
100 parts of PVA (saponification degree: 98.0 mol%, viscosity of 4% by weight aqueous solution: 52 mPa · s, polymerization degree: 2400) was charged in a kneader, and 30 parts of acetic acid was placed in it, swollen, and stirred at a rotational speed of 20 rpm. However, after raising the temperature to 60 ° C., 5 parts of diketene was added dropwise over 5 hours, and the reaction was further continued for 1 hour. After completion of the reaction, the product was washed with methanol and then dried at 70 ° C. for 12 hours to obtain AA-modified PVA (b1-1). The AA degree of the AA-modified PVA (b1-1) is 4.5 mol%, and the saponification degree and the average degree of polymerization are the same as the PVA used.

{Crosslinking reaction}
After blending and mixing 5 parts of a 10% aqueous solution of adipic acid dihydrazide with 100 parts of the 10% aqueous solution of AA-PVA (b1-1) obtained above, the paper (A) and resin layer (C ) And an applicator with a clearance of 50 μm, and dried at 70 ° C. for 5 minutes to form a cross-linked product layer (B) to obtain a laminate 1 of the present invention.
The layer structure of the laminated body 1 is as follows.
Paper (A) / resin layer (C) / cross-linked layer (B) = 60 μm / 20 μm / 5 μm
The obtained laminate 1 was evaluated as follows.

[Evaluation of yellowing]
The laminate 1 obtained above was allowed to stand for 28 days in a constant temperature and humidity machine at 40 ° C. and 90% RH to promote yellowing, and colorimetry was performed with a colorimeter. As a measuring device, a spectrocolorimeter CM-3600A (manufactured by Konica Minolta Sensing) was used, measured three times with a reflection method light source D-65, and the average value was evaluated.
The results are shown in Table 1.

Comparative Example 1
In Example 1, the polyester resin 1 was changed to the polyester resin 2 (“Polyester 905” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., molecular weight 16000, Tg 54 ° C., hydroxyl value 6 mgKOH / g, acid value 1.5 mgKOH / g). Except for the above, a laminate was prepared in the same manner as in Example 1, and each measurement and evaluation was performed. The results are shown in Table 1.

In Example 1 using the laminate of the present invention, the Δb ^* value was small and yellowing was small. On the other hand, in Comparative Example 1 in which the laminate of the present invention was not used, the Δb ^* value was large and the yellowing was large.

  The laminate of the present invention has little yellowing and is useful for wrapping paper, thermal recording media, and inkjet recording media.

Claims (7)

A laminate comprising a paper (A), a crosslinked product layer (B) obtained by reacting a modified group-containing polyvinyl alcohol resin (b1) having active hydrogen and a crosslinking agent (b2), and a resin layer (C). Yes,
In the ¹ H nucleus spin-spin relaxation time (T _2H ) of the resin layer (C), the long-term component amount (L _T2H ) and the short-term component amount (S _T2H ) satisfy the following formula (1). A laminate characterized by the above.

The laminate according to claim 1, wherein the modified group-containing polyvinyl alcohol resin (b1) having active hydrogen is an acetoacetyl group-containing polyvinyl alcohol resin (b1-1). The laminate according to claim 1, wherein the modified group-containing polyvinyl alcohol resin (b1) having active hydrogen is a diacetone acrylamide modified polyvinyl alcohol resin (b1-2). The laminated body according to any one of claims 1 to 3, wherein the resin constituting the resin layer (C) is a water-soluble polyester resin. The laminate according to any one of claims 1 to 4, further comprising a resin layer (C) between the paper (A) and the cross-linked product layer (B). A heat-sensitive recording medium comprising the laminate according to claim 1. An ink jet recording medium comprising the laminate according to any one of claims 1 to 5.