JP2016124172A - Method for producing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a composition comprising a PVA polymer and having excellent water resistance, and also provide a method for producing a laminate comprising a thermosensitive recording layer having excellent water resistance.SOLUTION: According to a method for producing a composition of the present invention, a composition comprising a vinyl alcoholic polymer (A) with a saponification degree of 95.0-99.99 mol% and a titanium compound and/or a zirconium compound (B) is subjected to wet heat treatment in an atmosphere at temperature of 40-60°C and humidity of 70-95%RH.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a composition heat treated under specific conditions containing a vinyl alcohol resin. Furthermore, it is related with the manufacturing method of the water-resistant composition containing a vinyl alcohol resin.

  Vinyl alcohol polymers (hereinafter sometimes abbreviated as PVA) are widely used as various binders, adhesives or surface treatment agents, and do not allow other water-soluble resins to follow in terms of film-forming properties and strength. It is known to have excellent performance. However, since PVA is water-soluble, there is a drawback that water resistance, particularly when dried at a low temperature, is low, and various methods have been studied in order to improve this drawback.

  For example, a method of crosslinking an acetoacetyl group-containing PVA with a polyvalent aldehyde compound such as glyoxal has been proposed, but there is a problem in the viscosity stability of the coating solution (Patent Document 1). A method of crosslinking acetoacetate group-containing PVA in the presence of an alkali metal acetate salt has also been proposed, but some improvement in viscosity stability is observed, but aldehydes are still used as a crosslinking agent. Therefore, consideration for the working environment is not sufficient (Patent Document 2). Furthermore, although a method of crosslinking a carboxyl group-containing PVA with a polyamide epichlorohydrin resin has been proposed, a curing time may be required to develop performance such as water resistance and plasticizer resistance, which is not always satisfactory. . In addition, epichlorohydrin is a substance harmful to the human body, so it is not preferable to use it. Then, although the method of using a zirconium compound for the crosslinking agent of carboxyl group-containing PVA is also proposed, an effect will not be recognized unless a zirconium compound is added in large quantities with respect to carboxyl group-containing PVA, and the degree of water resistance will also be achieved. This was not satisfactory (Patent Document 3).

JP 59-106995 A JP-A-9-11623 JP-A-1-101187

  This invention is made | formed in order to solve the said subject, and it aims at providing the manufacturing method of the composition excellent in water resistance containing a PVA-type polymer. Another object of the present invention is to provide a method for producing a laminate including a thermosensitive recording layer having excellent water resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a saponification degree is 95.0 to 99.99 mol%, a vinyl alcohol polymer (A), a titanium compound and / or a zirconium compound (B ), A method for producing a composition that has been heat-moisture treated in an atmosphere of a temperature of 40 to 60 ° C. and a humidity of 70 to 95% RH has been found, and the present invention has been completed.

  The vinyl alcohol polymer (A) is preferably a vinyl alcohol polymer having 0.01 to 2 mol% of silyl groups.

  The vinyl alcohol polymer (A) is preferably a vinyl alcohol polymer having 1 to 20 mol% of ethylene groups.

  The titanium compound (B) is preferably at least one selected from the group consisting of titanium lactate, titanium lactate ammonium salt, and diisopropyl titanium bis (triethanolaminate).

  The zirconium compound (B) is at least one selected from the group consisting of ammonium zirconium carbonate, zirconium ammonium acetate, zirconium ammonium sulfate, ammonium zirconium nitrate, zirconium ammonium iodide, zirconium ammonium fluoride, zirconium ammonium oxychloride, and zirconium ammonium oxyiodide. It is desirable that

  The heat-treated composition is preferably a laminate.

  It is desirable that the laminate includes a heat sensitive recording layer.

A composition comprising a vinyl alcohol polymer (A) having a saponification degree of 95.0 to 99.99 mol% and a titanium compound and / or a zirconium compound (B),
It is desirable that the composition has a degree of swelling of 1 to 10 when wet-heat treated in an atmosphere of a temperature of 40 to 60 ° C. and a humidity of 70 to 95% RH.

  In the method for producing the composition of the present invention, a composition containing a vinyl alcohol polymer having excellent water resistance can be obtained. Furthermore, by using the method for producing the composition in a method for producing a laminate including a heat-sensitive recording layer, a heat-sensitive recording material having excellent water resistance can be obtained.

(Vinyl alcohol polymer (A))
The vinyl alcohol polymer (A) used in the present invention can be obtained by saponifying a saponified vinyl ester polymer or a copolymer with another vinyl monomer copolymerizable with the vinyl ester. In carrying out the polymerization, a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method or an emulsion polymerization method can be employed. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is performed without solvent or in a solvent such as alcohol is usually employed, and an emulsion polymerization method is employed when obtaining a polymer having a high degree of polymerization. Examples of alcohol used as a solvent during solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Examples of the initiator used for the polymerization include α, α′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobis (4-methoxy). -2,4-dimethylvaleronitrile), known initiators such as azo initiators or peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of -30-150 degreeC is suitable.

  Examples of the vinyl ester monomer used in the above method include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate and the like, and generally vinyl acetate is used.

  In the present invention, the vinyl alcohol polymer (A) includes a modified PVA containing an α-olefin unit having 4 or less carbon atoms, a modified PVA having a silyl group in the molecule, and an α having 4 or less carbon atoms in the same molecule. -Modified PVA having an olefin unit and a silyl group is preferably used, as will be apparent from the examples described later.

  A method for producing a modified PVA containing an α-olefin unit having 4 or less carbon atoms can be obtained by saponifying a copolymer of a vinyl ester and an α-olefin having 4 or less carbon atoms. Examples of the α-olefin having 4 or less carbon atoms include ethylene, propylene, n-butene, isobutene, and the like, and ethylene is preferable from the viewpoint of obtaining the target composition of the present invention. The content of the α-olefin unit having 4 or less carbon atoms is preferably from 1 to 20 mol%, more preferably from 1.5 to 18 mol%, further preferably from 2 to 15 mol%, particularly preferably from 2 to 13 mol%. .

  As a method for producing a modified PVA containing a silyl group in the molecule, 1) a method in which a silyl group is introduced into PVA or a modified polyvinyl acetate containing a carboxyl group or a hydroxyl group by post-modification using a silylating agent; ) A method of saponifying a copolymer of a vinyl ester and a silyl group-containing olefinic unsaturated monomer, 3) A silyl group at the terminal obtained by polymerizing the vinyl ester in the presence of a mercaptan having a silyl group The method of saponifying the polyvinyl ester which has is mentioned.

  In a method for saponifying a copolymer of a vinyl ester and a silyl group-containing olefinic unsaturated monomer, for example, a vinyl ester and a silyl group-containing olefinic unsaturated monomer are mixed with a radical initiator in an alcohol. The silyl group-containing modified PVA can be obtained by copolymerization using the resulting solution, and then saponifying the copolymer by adding an alkali or acid catalyst to the alcohol solution of the copolymer. Examples of the vinyl ester used in the above method include vinyl acetate, vinyl propionate, vinyl formate, etc., but vinyl acetate is preferred from an economical viewpoint. Examples of the silyl group-containing olefinic unsaturated monomer used in the above method include vinyl silane represented by the following chemical formula 1, (meth) acrylamide-alkylsilane represented by chemical formula 2, and the like.

[Wherein n is 0 to 4, m is 0 to 2, R ¹ is an alkyl group having 1 to 5 carbon atoms (methyl, ethyl, etc.), and R ² is an alkoxyl group or acyloxyl group having 1 to 40 carbon atoms (wherein An alkoxyl group or an acyloxyl group may have an oxygen-containing substituent.), R ³ is a hydrogen atom or a methyl group, R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁵ is a carbon atom. A divalent organic residue having an alkylene group of 1 to 5 or a chain carbon atom bonded to each other by oxygen or nitrogen is shown. In the case where R ¹ is present twice that in the same monomer is may be R ¹ are the same and may be different. When two or more R ² are present in the same monomer, R ² may be the same or different. ]

  Specific examples of the vinylsilane represented by Chemical Formula 1 include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris- (β-methoxyethoxy) silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriacetoxysilane, vinyl Methyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltrihexa Siloxy silane, vinyl methoxy dihexyloxy silane, vinyl dimethoxy octyloxy silane, vinyl methoxy dioctyloxy silane, vinyl trioctyloxy Silane, vinyl methoxy dilaurate Lilo silane, vinyl dimethoxy Lau Lilo silane, vinyl methoxy geo Ray B silanes, vinyl dimethoxy I acetoxyphenyl silane.

  Specific examples of the (meth) acrylamide-alkylsilane represented by Chemical Formula 2 include, for example, 3- (meth) acrylamide-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane, 3- (meth) Acrylamide-propyltri (β-methoxyethoxy) silane, 2- (meth) acrylamide-2-methylpropyltrimethoxysilane, 2- (meth) acrylamide-2-methylethyltrimethoxysilane, N- (2- (meth) Acrylamide-ethyl) -aminopropyltrimethoxysilane, 3- (meth) acrylamide-propyltriacetoxysilane, 2- (meth) acrylamide-ethyltrimethoxysilane, 1- (meth) acrylamide-methyltrimethoxysilane, 3- ( (Meth) acrylamide Propylmethyldimethoxysilane, 3- (meth) acrylamide-propyldimethylmethoxysilane, 3- (N-methyl- (meth) acrylamide) -propyltrimethoxysilane, 3-((meth) acrylamide-methoxy) -3-hydroxy Propyltrimethoxysilane, 3-((meth) acrylamide-methoxy) -propyltrimethoxysilane, dimethyl-3- (meth) acrylamide-propyl-3- (trimethoxysilyl) -propylammonium chloride, dimethyl-2- (meth) ) Acrylamide-2-methylpropyl-3- (trimethoxysilyl) propylammonium chloride and the like.

  In the method of saponifying a polyvinyl ester having a silyl group at the terminal obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group, for example, when the vinyl ester is polymerized using a radical initiator, After a mercaptan having a group is added to the polymerization system all at once or in a divided or continuous manner, a mercaptan having a silyl group is present in the polymerization system, and a polyvinyl ester having a silyl group at the terminal is formed by chain transfer to the mercaptan. A modified PVA having a silyl group can be obtained by adding an alkali or acid catalyst to the alcohol solution of the polyvinyl ester to saponify the polyvinyl ester.

  As the mercaptan having a silyl group used in the present method, 3- (trimethoxysilyl) -propyl mercaptan or the like can be used. In producing the modified PVA by this method, an unsaturated monomer copolymerizable with the vinyl ester can be present in a small proportion.

  In the above-mentioned three production methods of modified PVA containing a silyl group in the molecule used in the present invention, a copolymer of a vinyl ester and an olefinically unsaturated monomer containing a silyl group is saponified. The method and the method of saponifying a polyvinyl ester having a silyl group at the terminal obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group are easy to industrially manufacture and the homogeneity of the resulting modified PVA Are preferably used.

  In the present invention, the content of silyl groups, the degree of saponification or the degree of polymerization in PVA (A) are appropriately selected according to the purpose and are not particularly limited. The effect of the silyl group is exhibited even with a relatively small content, and usually 0.01 to 2 mol%, preferably 0.02 to 1.7 mol%, more preferably 0 as a monomer unit containing a silyl group. It is selected from the range of 0.03 to 1.5 mol%. Optimally, it is 0.05-1 mol%.

  In the present invention, PVA (A) is most preferably modified PVA having the above-mentioned α-olefin unit and silyl group in the same molecule, and such modified PVA is, for example, the above-described α-olefin having 4 or less carbon atoms, It is obtained by copolymerizing a vinyl ester and a silyl group-containing olefinic unsaturated monomer and further saponifying.

  When the PVA used in the present invention is dissolved in water, a homogeneous aqueous solution is usually obtained by adding an alkali such as sodium hydroxide in some cases after dispersing the modified PVA in water and heating with stirring. Can do.

  The PVA (A) used in the present invention may be one obtained by copolymerizing an ethylenically unsaturated monomer copolymerizable with a vinyl ester as long as the effects of the present invention are not impaired. Examples of such ethylenically unsaturated monomers include olefins such as propylene, 1-butene, and isobutene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, (anhydrous) maleic acid, and itaconic acid. Or a salt thereof or a mono- or dialkyl ester thereof having 1 to 18 carbon atoms; acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N 2, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethyl Acrylamides such as amines or acid salts thereof or quaternary salts thereof; methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamide propanesulfonic acid or salts thereof, methacryl Amide Methacrylamide such as propyldimethylamine or its acid salt or quaternary salt thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide; vinyl cyanide such as acrylonitrile, methacrylonitrile, etc. Vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide; allyl acetate, Allyl chloride, allyl alcohol, dimethylallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) ammonium chloride, acrylamido-2-methylpropanesulfonate, C 1-2 Such as hydroxyalkyl group-containing α- olefins. In the vinyl alcohol polymer (A) used in the present invention, the content of monomer units derived from these ethylenically unsaturated monomers is preferably 20 mol% or less.

Further, the viscosity average degree of polymerization (hereinafter abbreviated as “degree of polymerization”) of PVA (A) used in the present invention is not particularly limited, but is preferably 50 to 10,000, more preferably 100 to 8,000. 100 to 4000 is more preferable. For example, when used as a binder for a heat-sensitive recording layer, the polymerization degree of PVA (A) is usually preferably 500 to 3000. When used for the surface protective layer or the undercoat layer of the laminate including the thermosensitive recording layer, the polymerization degree of PVA (A) is preferably a relatively medium to high polymerization degree of usually 1000 to 4000. When the degree of polymerization of the vinyl alcohol polymer (A) is less than 50, even if the vinyl alcohol polymer is used as a binder or a surface protective layer, the desired performance is not exhibited. The laminated body containing cannot be obtained. When the degree of polymerization of the vinyl alcohol polymer (A) is greater than 10,000, if the vinyl alcohol polymer is used as a binder, the density of the printed part of the heat-sensitive recording layer is reduced, or the vinyl alcohol polymer weight is reduced. The viscosity of the combined aqueous dispersion becomes too high, making it difficult to handle, making it impossible to increase the solid content concentration of the aqueous dispersion, and using the vinyl alcohol polymer in the surface protective layer. The viscosity of the polymer solution becomes too high, making it difficult to handle and a uniform layer cannot be obtained.

  The saponification degree of the vinyl alcohol polymer (A) used in the present invention is 95.0 to 99. It is 99 mol%, preferably 98.0 to 99.9 mol%, and more preferably 99.0 to 99.9 mol%. When the degree of saponification of PVA (A) is lower than 95.0 mol%, the water resistance improvement effect that can be expected in this method is lowered. On the other hand, when the degree of saponification of the vinyl alcohol polymer (A) is larger than 99.99 mol%, the density of the printed part of the heat-sensitive recording layer is lowered, and the viscosity of the aqueous dispersion becomes too high to handle. It becomes difficult and the solid content concentration of the aqueous dispersion cannot be increased.

  In dissolving the vinyl alcohol polymer (A) used in the present invention in water, usually after dispersing the vinyl alcohol polymer (A) in water, in some cases, an alkali such as sodium hydroxide is added, A uniform aqueous solution can be obtained by heating with stirring.

(Titanium compound)
The titanium compound (B) used in the present invention is at least one selected from the group consisting of titanium lactate, titanium lactate ammonium salt, and diisopropyl titanium bis (triethanolaminate).

(Zirconium compound)
Examples of the zirconium compound (B) used in the present invention include ammonium zirconium carbonate, zirconium oxychloride, zirconium sulfate, zirconium nitrate, zirconium acetate, zirconium carbonate, zirconium stearate, zirconium octylate, and zirconium silicate. Among these zirconium compounds, water-soluble ones are preferable, and specific examples include zirconium sulfate, zirconium nitrate, zirconium acetate, ammonium zirconium carbonate, zirconium oxychloride, and particularly a surface protective layer of a laminate including a thermosensitive recording layer and When used for the undercoat layer, ammonium zirconium carbonate is most preferred. These zirconium compounds are not necessarily used alone, and may be used in combination of two or more as required.

  In the heat-sensitive recording material of the present invention, the weight blending ratio (B) / (A) of the vinyl alcohol polymer (A) and the titanium and / or zirconium compound (B) is not particularly limited, but 0.0 / 100 0.0 ≦ (B) / (A) ≦ 20/80, more preferably 0.2 / 99.8 ≦ (B) / (A) ≦ 17/83, 0.5 / It is particularly preferable that 99.5 ≦ (B) / (A) ≦ 15/85. (B) If / (A) is greater than 20/80, the viscosity stability of the aqueous solution of the composition comprising the vinyl alcohol polymer (A) and titanium and / or zirconium compound (B) may be reduced. is there.

  The composition of the present invention is preferably a laminate in which a plurality of layers including a thermosensitive coloring layer are provided on a substrate. More preferably, it is a laminate in which a surface protective layer is provided on the surface of the thermosensitive coloring layer provided on the substrate. In the case where paper is used as the substrate, it is also a preferable form to further provide an undercoat layer. These laminates can be used as heat-sensitive recording materials.

  In the present invention, the vinyl alcohol polymer (A) and the titanium compound and / or zirconium compound (B) are contained in any layer such as a heat-sensitive color developing layer, a surface protective layer, and an undercoat layer in the heat-sensitive recording material. be able to. Here, the thermosensitive coloring layer is a layer containing a thermosensitive dye, a developer and a dispersant, the surface protective layer is a layer provided on the thermosensitive coloring layer, and the undercoat layer is a thermosensitive coloring layer. It is a layer provided between the substrate. The vinyl alcohol polymer (A) and titanium compound and / or zirconium compound (B) used in the present invention are included in at least one of the above layers.

  The total content of the vinyl alcohol polymer (A) and the titanium compound and / or zirconium compound (B) in the thermosensitive coloring layer of the thermosensitive recording material is not particularly limited, but the water resistance and sensitivity of the thermosensitive recording material are not limited. From the viewpoint, the amount is preferably 3 to 280 parts by weight, more preferably 5 to 250 parts by weight, and more preferably 8 to 200 parts by weight with respect to 100 parts by weight of the total amount of the thermal dye and the developer. Further preferred.

  Further, in the present invention, when a composition comprising the vinyl alcohol polymer (A) and a titanium compound and / or a zirconium compound is used as an aqueous binder for a heat-sensitive color developing layer, a film having particularly excellent strength and water resistance. Is obtained. When the composition comprising the vinyl alcohol polymer (A) and the titanium compound and / or zirconium compound is used as the aqueous binder of the thermosensitive coloring layer, the total of the vinyl alcohol polymer (A) and the titanium compound and / or zirconium compound Is preferably 5 to 80 parts by weight based on 100 parts by weight of the total amount of the thermal dye and the developer.

  When preparing an aqueous dispersion of a thermal dye or a developer in the present invention, the above-mentioned vinyl alcohol polymer (A) can be used as a dispersant, and other known vinyl alcohol polymers. (Modified vinyl alcohol polymers such as non-modified polyvinyl alcohol and carboxyl-modified polyvinyl alcohol) and the like can also be used as a dispersant. The amount of the dispersant used is not particularly limited, but is preferably 3 to 200 parts by weight, more preferably 5 to 180 parts by weight with respect to 100 parts by weight of the total amount of the thermal dye and the developer. 8 to 150 parts by weight is more preferable. Usually, it is preferable to prepare an aqueous dispersion of a thermal dye and an aqueous dispersion of a developer separately, and then mix and use both. The concentration of the dispersoid in the aqueous dispersion is preferably 20 to 70% by weight, more preferably 40 to 60% by weight.

  The thermal dye used in the present invention may be any thermal dye that can be used for general thermal recording paper. As specific examples, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3- (p-dimethylaminophenyl) -3- (1,2- Dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis- (9-ethylcarbazol-3-yl)- Triarylmethane compounds such as 5-dimethylaminophthalide; Diphenylmethane compounds such as 4,4′-bisdimethylaminobenzhydrin benzyl ether and N-halophenylleucooramine; Rhodamine B-anilinolactam, 3- Diethylamino-7-benzylaminofluorane, 3-diethylamino-7-butylaminofluor 3-diethylamino-7- (chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6 -Methyl-7-anilinofluorane, 3-cyclohexyl-methylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7- (β-ethoxyethyl) aminofluorane, 3- Diethylamino-6-chloro-7- (γ-chloropropyl) aminofluorane, 3- (N-ethyl-N-isoamyl) -6-methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl- Xanthene compounds such as 7-anilinofluorane; benzoylleucomethylene blue, p-nitrobenzoylroy Thiazine compounds such as methylene blue; spiro compounds such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methylnaphtho- (3-methoxy-benzo) -spiropyran, etc. These may be used alone or in admixture of two or more. These thermal dyes are appropriately selected depending on the use of the thermal recording material.

  As the developer used in the present invention, a phenol derivative and an aromatic carboxylic acid derivative are preferable, and bisphenols are particularly preferable. Specifically, as phenols, p-octylphenol, p-tert-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) -2-ethyl-hexane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, dihydroxydiphenyl ether and the like, and aromatic carboxylic acid derivatives include p-hydroxybenzoic acid and p-hydroxybenzoic acid. Ethyl, p-hydroxybenzoate, 3,5-di-tert-butyl Rusarichiru acid, 3,5 - di -α- methylbenzyl salicylic acid, such as polyvalent metal salts of the above carboxylic acids.

  In the present invention, as a method for forming the thermosensitive coloring layer, known coating methods such as an air knife method, a brate method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method can be used. is there.

  In the present invention, by using a composition comprising a vinyl alcohol polymer (A) and a titanium compound and / or a zirconium compound (B), the thermosensitive coloring layer, the surface protective layer, or the substrate and the thermosensitive coloring layer In addition to being able to impart excellent film forming performance to the intermediate undercoat layer, it is possible to impart excellent water resistance, plasticizer resistance, oil resistance and organic solvent resistance to the resulting film.

In the present invention, as a method for forming the surface protective layer and the undercoat layer, known coating methods such as an air knife method, a plate method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method are used. Is available. The coating amount of the surface protective layer in the heat-sensitive recording material is appropriately selected as long as the heat conduction from the thermal head of the heat-sensitive recording apparatus to the color-developing layer of the heat-sensitive recording material is not hindered, but usually 1 to 10 g / m ^2. , Preferably ² to 7 g / m ² .

  In the present invention, in order to prevent color development of the thermosensitive coloring layer during coating drying after coating, a thermosensitive recording material obtained under relatively low temperature drying conditions of 70 ° C. or less, particularly room temperature to 50 ° C. is used. It is essential to perform wet heat treatment at -60 ° C and a humidity of 70-90% RH. The wet heat treatment temperature is more preferably 45 to 60 ° C. When the temperature of the wet heat treatment is less than 40 ° C., the resulting heat-sensitive recording material has insufficient water resistance. On the other hand, when the temperature of the wet heat treatment exceeds 60 ° C., fogging due to coloring of the obtained heat-sensitive recording material tends to occur. The humidity of the wet heat treatment is more preferably 75 to 90% RH. When the humidity of the wet heat treatment is less than 70% RH, the resulting heat-sensitive recording material has insufficient water resistance. On the other hand, when the humidity of the wet heat treatment exceeds 90% RH, the resulting heat-sensitive recording material contains excessive moisture, so that blocking tends to occur.

  In addition, the thermosensitive coloring layer, the surface protective layer, and the undercoat layer may each include a solvent, a water-soluble or water-dispersible resin, a polymer aqueous dispersion, a filler, a lubricant, A foaming agent, a dispersing agent, a nonionic or anionic surfactant, a silane coupling agent, a pH adjusting agent, a wetting agent, a pressure coloring inhibitor, and the like can be blended.

  Here, water is preferably used as the above-mentioned solvent, but various alcohols, ketones, dimethylformamide, dimethylsulfoxide and other solvents can be used in combination.

  Examples of the water-soluble or water-dispersible resin include cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose; carboxyl group-containing modified PVA, sulfonic acid group-containing modified PVA, phosphate group-containing modified PVA, 4 PVA derivatives such as secondary ammonium base-containing modified PVA; ordinary PVA, alkali salt of (meth) acrylic acid ester copolymer, polyvinylpyrrolidone, (meth) acrylamide / (meth) acrylic acid ester copolymer, styrene / anhydrous maleic acid Alkali salt of acid copolymer, alkali salt of isobutylene / maleic anhydride copolymer, alkali salt of diisobutylene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casei , And the like gum arabic.

  Examples of the polymer aqueous dispersion include polyvinyl acetate, polyurethane, (meth) acrylic acid polymer or copolymer, acrylate polymer or copolymer, hydroxy (meth) acrylate polymer or copolymer, Examples thereof include emulsions such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, and ethylene / vinyl acetate copolymer; latex such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer.

  Examples of the lubricant include higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, paraffin wax, and microcrystalline wax.

  Further, the fillers include kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, silica, aluminum oxide, aluminum hydroxide, synthetic aluminum silicate, synthetic magnesium silicate, polystyrene fine particles, poly Examples thereof include vinyl acetate fine particles and urea-formalin resin fine particles. In particular, when these fillers are used as a surface protective layer forming agent, it is preferable to use 20% by weight or more of all components of the surface protective layer as the filler to improve the water resistance, oil resistance and plasticizer resistance of the heat sensitive recording material. This is preferable from the point of view.

  The swelling degree of the composition obtained by the production method of the present invention is preferably 1 to 10. The degree of swelling is more preferably 1-8. The swelling degree is more preferably 1-6. When the degree of swelling of the composition is less than 1, the resulting heat-sensitive recording material becomes brittle in a low humidity environment. On the other hand, when the degree of swelling of the composition exceeds 8, the resulting heat-sensitive recording material has insufficient water resistance. The degree of swelling of the composition is a value measured by the method described later.

  In the present invention, the support material of the heat-sensitive recording material is not particularly limited, and for example, paper, synthetic fiber paper, synthetic resin film and the like can be used as appropriate. Among them, it is generally preferable to use paper.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, “%” and “parts” mean “% by weight” and “parts by weight”, respectively, unless otherwise specified.

(Synthesis of PVA-1)
1300 g of vinyl acetate, 557 g of methanol and 2.5 g of vinyltriethoxysilane were charged into a reaction vessel equipped with a stirrer, thermometer, dropping funnel, nitrogen gas inlet tube and reflux condenser, and the inside of the system was purged with nitrogen while stirring. The internal temperature was raised to 60 ° C. To this system, 50 ml of a methanol solution containing 0.3 g of 2,2′-azobisisobutyronitrile was added to initiate polymerization. The polymerization was stopped after 4 hours, and the polymerization rate at that time was 30%. The solution adjusted to 25% was saponified by adding a NaOH methanol solution (10% concentration) so that the alkali molar ratio (number of moles of NaOH / number of moles of vinyl ester units in the modified PVAc) was 0.015. . The degree of saponification of the obtained modified PVA was 98.5 mol%. The methanol solution of the modified PVAc obtained by removing the unreacted vinyl acetate monomer after the polymerization was poured into n-hexane to precipitate the modified PVAc, and reprecipitation purification was performed three times by dissolving the recovered modified PVAc with acetone. Thereafter, the product was dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVAc. The content of vinyltrimethoxysilane units determined from proton NMR measurement of the modified PVAc was 0.2 mol%. After saponifying the methanol solution of the above modified PVAc at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was performed for 3 days, and then dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVA. The average degree of polymerization of the modified PVA was 1700 as measured according to JIS K6726 of the ordinary method. By the above operation, a modified PVA having a polymerization degree of 1700, a saponification degree of 98.5 mol%, and a vinyltrimethoxysilane content of 0.2 mol% was obtained.

(Synthesis of PVA-2)
A 50 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 23.5 kg of vinyl acetate and 6.5 kg of methanol, heated to 60 ° C., and nitrogen bubbling for 30 minutes. The inside was replaced with nitrogen. Next, ethylene was introduced and charged so that the reactor pressure was 0.4 MPa. A 2.8 g / L solution having 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) dissolved in methanol as an initiator was prepared, and nitrogen substitution was performed by bubbling with nitrogen gas. After adjusting the temperature inside the reaction vessel to 60 ° C., 7 mL of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 0.2 MPa, the polymerization temperature at 60 ° C., and the above initiator solution was continuously added at 22 mL / hr. After 4 hours, when the polymerization rate reached 30%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of ethylene-modified PVAc. The solution adjusted to 25% was saponified by adding a NaOH methanol solution (10% concentration) so that the alkali molar ratio (number of moles of NaOH / number of moles of vinyl ester units in the modified PVAc) was 0.015. . The degree of saponification of the obtained modified PVA was 98.5 mol%. The methanol solution of the modified PVAc obtained by removing the unreacted vinyl acetate monomer after the polymerization was poured into n-hexane to precipitate the modified PVAc, and reprecipitation purification was performed three times by dissolving the recovered modified PVAc with acetone. Thereafter, the product was dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVAc. The content of ethylene units determined from proton NMR measurement of the modified PVAc was 4 mol%. After saponifying the methanol solution of the above modified PVAc at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was performed for 3 days, and then dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVA. The average degree of polymerization of the modified PVA was 1700 as measured according to JIS K6726 of the ordinary method. By the above operation, a modified PVA having a polymerization degree of 1700, a saponification degree of 98.5 mol% and an ethylene content of 4 mol% was obtained.

(Synthesis of PVA-3)
A 5 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 2460 g of vinyl acetate, 515 g of methanol, and 7 g of vinyltrimethoxysilane, heated to 60 ° C., and then bubbled with nitrogen for 30 minutes. The system was replaced with nitrogen. Next, ethylene was introduced and charged so that the reactor pressure was 0.5 MPa. A 0.9 g / L solution having di-n-propyldipercarbonate dissolved in methanol as an initiator was prepared, and nitrogen substitution was performed to perform bubbling with nitrogen gas. After adjusting the temperature inside the reaction vessel to 60 ° C., 33 mL of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 0.5 MPa, the polymerization temperature at 60 ° C., and the above initiator solution was continuously added at 37 mL / hr. After 4 hours, when the polymerization rate reached 50%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of modified PVAc. The solution adjusted to 25% was saponified by adding NaOH methanol solution (10% concentration) so that the alkali molar ratio (number of moles of NaOH / number of moles of vinyl ester units in the modified PVAc) was 0.030. . The degree of saponification of the obtained modified PVA was 98.5 mol%. The methanol solution of the modified PVAc obtained by removing the unreacted vinyl acetate monomer after the polymerization was poured into n-hexane to precipitate the modified PVAc, and reprecipitation purification was performed three times by dissolving the recovered modified PVAc with acetone. Thereafter, the product was dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVAc. The content of ethylene units determined from proton NMR measurement of the modified PVAc was 3 mol%, and the content of vinyltrimethoxysilane units was 0.3 mol%. After saponifying the methanol solution of the above modified PVAc at an alkali molar ratio of 0.2, Soxhlet extraction with methanol was performed for 3 days, and then dried under reduced pressure at 60 ° C. to obtain a purified product of modified PVA. When the average degree of polymerization of the modified PVA was measured according to JIS K6726 of a conventional method, it was 1300. By the above operation, a modified PVA having a polymerization degree of 1300, a saponification degree of 98.5 mol%, an ethylene content of 3 mol% and a silanol content of 0.3 mol% was obtained.

Example 1
(1) Preparation of coating liquid for surface protective layer A 6% aqueous solution of PVA117 (degree of saponification 98.5 mol%, degree of polymerization 1700: manufactured by Kuraray) was prepared. Polyacrylic acid soda (Toagosei Co., Ltd., Aron T-50) 0.2 part, UW-90 (component: Kaolin, Engelhardt) 38.8 parts of water 60 parts are added and using a disperser 3000 rpm Was stirred for 20 minutes to prepare a kaolin-dispersed aqueous solution. While stirring the obtained kaolin-dispersed aqueous solution at room temperature, 452 parts of the PVA aqueous solution and 3.5 parts of Orgatics TC-315 (titanium lactate: manufactured by Matsumoto Fine Chemical Co., Ltd.) are slowly added and stirred to a predetermined amount. By adding and mixing water, a surface protective layer coating solution having a solid content of 12% was prepared.

(2) Production of thermal recording paper The surface protective layer coating solution prepared in (1) above was applied to the surface of a commercial thermal paper (basis weight: 52 g / m ² : manufactured by KOKUYO) without an overcoat layer. After applying 1.5 g / m ^{2 in} terms of solid content using a bar coater, it was dried at 50 ° C. for 5 minutes. Thereafter, the coated paper was surface-treated with a soft super calender (linear pressure: 100 kg / cm, roll temperature: 40 ° C.). The coated paper was stored in a constant temperature and humidity machine at 40 ° C. and 90% RH for 24 hours and subjected to wet heat treatment to obtain a thermal recording paper.

(Water resistance test)
A few drops of water were dropped on the coated surface of the coated paper, and the portion was rubbed with a fingertip until the filler was removed, and the water resistance was evaluated in the following four stages.
A: The filler did not fall off even after rubbing 30 times or more.
B: The filler dropped out 10 times or more and less than 30 times.
C: The filler dropped out after 3 times or more and less than 10 times.
D: Filler dropped out in less than 3 times.

(Evaluation of water resistance of film)
PVA117 (degree of saponification 98.5 mol%, degree of polymerization 1700: manufactured by Kuraray) was dissolved in a predetermined amount of water to prepare a 4% strength aqueous solution. Next, 3.5 parts of ORGATICS TC-315 (titanium lactate: manufactured by Matsumoto Fine Chemical Co., Ltd.) was added to 452 parts of a 4% strength aqueous solution of PVA117 and mixed. The prepared mixed solution was cast at 20 ° C. and allowed to stand at 20 ° C. for one week to obtain a film having a thickness of 50 μm. What cut out this film | membrane to the magnitude | size of 8 cm in length and 5 cm in width was used as the test piece. Next, it was stored in a constant temperature and humidity machine at 40 ° C. and 90% RH for 24 hours and subjected to wet heat treatment. The treated specimen was dipped in distilled water at 20 ° C. for 16 hours and then collected. The moisture adhering to the surface was wiped off with gauze, and the weight (a) at that time was measured. This test piece was further dried at 105 ° C. for 3 hours, and the weight (b) at that time was measured. A value (a / b) obtained by dividing the weight (a) of the test piece of the same size by the weight (b) was calculated as the degree of swelling. The water resistance of the PVA film was evaluated in the following four stages.
A: The degree of swelling was less than 7 times.
B: The swelling degree was 7 times or more and less than 10 times.
C: The swelling degree was 10 times or more and less than 20 times.
D: The swelling degree was 20 times or more, or the PVA film was dissolved.

Examples 2-9
The water resistance of the film and the thermal recording paper was evaluated in the same manner as in Example 1 except that the PVA type, the crosslinking agent type and addition amount, and the wet heat treatment conditions were changed to the contents shown in Table 1. The results are shown in Table 1.

Comparative Examples 1-5
The water resistance of the film and the thermal recording paper was evaluated in the same manner as in Example 1 except that the PVA type, the crosslinking agent type and addition amount, and the wet heat treatment conditions were changed to the contents shown in Table 1. The results are shown in Table 1.

  As shown in the above Examples, a composition containing a vinyl alcohol polymer having a saponification degree of 95.0 to 99.99 mol% and a titanium compound and / or a zirconium compound is heated at a temperature of 40 to 60 ° C. and a humidity of 70. A film excellent in water resistance and a heat-sensitive recording material were obtained by a production method in which heat-moisture treatment was performed in an atmosphere of ˜95% RH (Examples 1 to 9). In particular, when the vinyl alcohol polymer is a vinyl alcohol polymer having 0.01 to 2 mol% of a silyl group or a vinyl alcohol polymer having 1 to 20 mol% of an ethylene group, it is more resistant to water. Excellent results were obtained (Examples 5 to 7). Further, when the vinyl alcohol polymer is a vinyl alcohol polymer having 0.01 to 2 mol% of silyl group and 1 to 20 mol% of ethylene group in the same molecule, the water resistance is particularly excellent. Was obtained (Example 7).

Claims (8)

  A composition containing a vinyl alcohol polymer (A) having a saponification degree of 95.0 to 99.99 mol% and a titanium compound and / or a zirconium compound (B) at a temperature of 40 to 60 ° C. and a humidity of 70 to 95% RH The manufacturing method of the composition heat-moisture-treated in the atmosphere of.   The method for producing a composition according to claim 1, wherein the vinyl alcohol polymer (A) is a vinyl alcohol polymer having 0.01 to 2 mol% of a silyl group.   The method for producing a composition according to claim 1, wherein the vinyl alcohol polymer (A) is a vinyl alcohol polymer having 1 to 20 mol% of ethylene groups.   The said titanium compound (B) is at least 1 type chosen from the group which consists of titanium lactate, titanium lactate ammonium salt, and diisopropyl titanium bis (triethanolaminate), The manufacture of the composition as described in any one of Claims 1-3. Method.   The zirconium compound (B) is at least one selected from the group consisting of ammonium zirconium carbonate, zirconium ammonium acetate, zirconium ammonium sulfate, ammonium zirconium nitrate, zirconium ammonium iodide, zirconium ammonium fluoride, zirconium ammonium oxychloride, and zirconium ammonium oxyiodide. The method for producing a composition according to any one of claims 1 to 3.   The method for producing a composition according to any one of claims 1 to 5, wherein the heat-treated composition is a laminate.   The method for producing a composition according to claim 6, wherein the laminate includes a thermosensitive recording layer. A composition comprising a vinyl alcohol polymer (A) having a saponification degree of 95.0 to 99.99 mol% and a titanium compound and / or a zirconium compound (B),
A composition having a swelling degree of 1 to 10 when wet-heat treated in an atmosphere of a temperature of 40 to 60 ° C. and a humidity of 70 to 95% RH.