JP2004043817A - Vinyl alcohol polymer and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silyl-group-containing PVA which is soluble even in the absence of an alkali (e.g. sodium hydroxide) or an acid in preparing an aqueous solution, gives an aqueous solution having a stable viscosity, a film obtained from the aqueous solution and having a satisfactory water resistance, and an inorganic-substance-containing film having a satisfactory water resistance, and exhibits a satisfactory power for binding an inorganic substance. <P>SOLUTION: The vinyl alcohol polymer is obtained by saponifying a vinyl ester polymer having monomer units having specific silyl groups and satisfies inequality (I): 20≤Pw×S≤460 [wherein Pw is the weight average degree of polymerization of the vinyl alcohol polymer; and S is the content (mol%) of the monomer unit containing a silyl group], provided that in the vinyl alcohol polymer, the weight fraction of a polymer having a degree of polymerization higher than three times the weight average degree of polymerization is 25 wt% or lower. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a vinyl alcohol polymer. More specifically, the present invention can prepare an aqueous solution by dissolving in water without adding an alkali or acid such as sodium hydroxide; the aqueous solution has excellent viscosity stability; Films obtained from aqueous solutions have excellent water resistance; excellent binder strength with inorganic substances; films obtained from mixtures with inorganic substances have excellent water resistance, etc. Regarding coalescence.
The present invention also relates to a method for producing the above vinyl alcohol polymer. Furthermore, the present invention relates to a coating agent containing the above-described vinyl alcohol polymer, and a coated material such as an ink jet recording material or a heat-sensitive recording material obtained by coating the coating agent on a substrate.

A vinyl alcohol polymer represented by polyvinyl alcohol (hereinafter, the vinyl alcohol polymer may be abbreviated as “PVA”) is known as a water-soluble synthetic polymer, and is used as a raw material for synthetic fiber vinylon. In addition, it is widely used in applications such as paper processing, fiber processing, adhesives, stabilizers for emulsion polymerization and suspension polymerization, inorganic binders, and films. PVA is particularly superior in strength properties and film-forming properties compared to other synthetic polymers, and is used as a clear coating agent to improve the surface properties of paper by taking advantage of its properties, or as a binder in pigment coating. ing.
Various attempts have been made to modify PVA in order to expand the use of PVA, and one of the attempts is the introduction of silicon (silyl group) into PVA. Silyl group-containing PVA is particularly excellent in water resistance, reactivity to inorganic substances, and adhesion. As a method for producing a silyl group-containing PVA, for example, a method is known in which a silylating agent such as triethylchlorosilane is dissolved in an organic solvent, and then powdered PVA is added and reacted with stirring (patent) Reference 1). However, this method has drawbacks that it is difficult to obtain a uniform modified product, and that it is necessary to react PVA with a silylating agent separately from the production of PVA. It is hard to say that this is a possible method.

As a method for producing a silyl group-containing PVA that solves these problems, for example, a method of saponifying a copolymer of vinyl alkoxysilane such as vinyltriethoxysilane and vinyl acetate (Patent Document 2), an acrylamide derivative having a silyl group A method of saponifying a copolymer of a vinyl ester such as vinyl acetate (Patent Document 3), A method of saponifying a copolymer of a vinyl ester and a monomer containing a silyl group having a specific substituent (Patent Document 3) Document 4), a method of saponifying a copolymer of an allyl monomer having a silyl group and a vinyl ester (Patent Document 5) has been proposed.
However, the silyl group-containing PVA obtained by these methods is (a) when an aqueous solution of silyl group-containing PVA is prepared, unless an alkali or acid such as sodium hydroxide is added, the silyl group-containing PVA is converted into water. (B) the viscosity stability of the aqueous solution of silyl group-containing PVA is not sufficient, (c) the water resistance of the film obtained from the aqueous solution of silyl group-containing PVA is not sufficient, d) When a film containing a silyl group-containing PVA and an inorganic substance is formed, it is difficult to satisfy both the binder force between the silyl group-containing PVA and the inorganic substance and the water resistance of the film at the same time. Have problems such as.
A silyl group-containing PVA into which an ionic hydrophilic group is introduced has been proposed (Patent Document 6), and it has been reported that PVA having a silanol group in the side chain has a strong interaction with an inorganic substance (Non-Patent Document). However, it is difficult to say that the above problems (a) to (d) have been solved by 1) such modified PVA.

JP 55-164614 A JP 50-123189 A JP 58-59203 A JP 58-79003 A JP 58-164604 A JP 59-182803 A Journal of the Chemical Society of Japan, 1994, No. 4, pages 365-370

The present invention can prepare an aqueous solution by dissolving in water without adding an alkali or acid such as sodium hydroxide; the aqueous solution has excellent viscosity stability; obtained from the aqueous solution The film is excellent in water resistance; excellent in binder strength with inorganic substances; and the film obtained from a mixture with inorganic substances is excellent in water resistance. The purpose is to provide coalescence.
The present invention also provides a method for producing the above vinyl alcohol polymer, a coating agent containing the above vinyl alcohol polymer, and an ink jet recording material or a heat sensitive recording material obtained by coating the coating agent on a substrate. The purpose is to provide a coated product.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a vinyl alcohol polymer containing a silyl group that satisfies certain requirements does not require addition of an alkali or acid such as sodium hydroxide. It is also possible to prepare an aqueous solution by dissolving in water; the aqueous solution has excellent viscosity stability; the film obtained from the aqueous solution is excellent in water resistance; The present inventors have found that a film obtained from a mixture with an inorganic material has characteristics such as excellent water resistance, and completed the present invention. That is, the present invention provides the following general formula (1):

（Ｒ^１は炭素数１〜５のアルキル基であり、Ｒ^２はアルコキシル基またはアシロキシル基であって、これらの基は酸素を含有する置換基を有していてもよく、ｍは０〜２の整数である。）
で示されるシリル基を有する単量体単位を含有するビニルエステル系重合体をけん化することによって得られるビニルアルコール系重合体であって、下記式（Ｉ）を満足し、かつビニルアルコール系重合体の中で、その重合度が重量平均重合度の３倍を超える重合体の重量分率が２５重量％以下であることを特徴とするビニルアルコール系重合体である。
　　２０＜Ｐｗ×Ｓ＜４６０　・・・（Ｉ）
Ｐｗ：ビニルアルコール系重合体の重量平均重合度
Ｓ：一般式（１）で示されるシリル基を有する単量体単位の含有量（モル％）

(R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have an oxygen-containing substituent, and m is 0 to 2 Is an integer.)
A vinyl alcohol polymer obtained by saponifying a vinyl ester polymer containing a monomer unit having a silyl group represented by formula (1), which satisfies the following formula (I) and is a vinyl alcohol polymer: Among them, the vinyl alcohol polymer is characterized in that the weight fraction of the polymer having a degree of polymerization exceeding 3 times the weight average degree of polymerization is 25% by weight or less.
20 <Pw × S <460 (I)
Pw: Weight average polymerization degree of vinyl alcohol polymer S: Content of monomer unit having silyl group represented by general formula (1) (mol%)

The silyl group-containing vinyl alcohol polymer of the present invention can be dissolved in water to prepare an aqueous solution without adding an alkali or acid such as sodium hydroxide, and the viscosity of the prepared aqueous solution can be stabilized. Performance, water resistance of a film obtained from the aqueous solution, water resistance of a film containing an inorganic substance, and binder strength with an inorganic substance at the same time. Excellent performance as a coating agent used in combination with an inorganic substance in various applications. Have In addition, by applying a coating agent containing the silyl group-containing vinyl alcohol polymer of the present invention to a substrate, an ink jet recording material and a heat sensitive recording material excellent in various performances such as water resistance can be obtained.

As described above, the vinyl alcohol polymer of the present invention has the following general formula (1)

（Ｒ^１は炭素数１〜５のアルキル基であり、Ｒ^２はアルコキシル基またはアシロキシル基であって、これらの基は酸素を含有する置換基を有していてもよく、ｍは０〜２の整数である。）
で示されるシリル基を有する単量体単位を含有するビニルエステル系重合体をけん化することによって得られるビニルアルコール系重合体であって、下記式（Ｉ）を満足し、かつビニルアルコール系重合体の中で、その重合度が重量平均重合度の３倍を超える重合体の重量分率が２５重量％以下であることが必要である。
　　２０＜Ｐｗ×Ｓ＜４６０　・・・（Ｉ）
Ｐｗ：ビニルアルコール系重合体の重量平均重合度
Ｓ：一般式（１）で示されるシリル基を有する単量体単位の含有量（モル％）

(R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have an oxygen-containing substituent, and m is 0 to 2 Is an integer.)
A vinyl alcohol polymer obtained by saponifying a vinyl ester polymer containing a monomer unit having a silyl group represented by formula (1), which satisfies the following formula (I) and is a vinyl alcohol polymer: Among these, it is necessary that the weight fraction of the polymer whose degree of polymerization exceeds 3 times the weight average degree of polymerization is 25% by weight or less.
20 <Pw × S <460 (I)
Pw: Weight average polymerization degree of vinyl alcohol polymer S: Content of monomer unit having silyl group represented by general formula (1) (mol%)

In the vinyl alcohol polymer of the present invention, the product (Pw × S) of the weight average polymerization degree (Pw) of the vinyl alcohol polymer and the content (S) of the monomer unit having a silyl group is 20 <Pw × It is necessary to satisfy the relationship of S <460. Pw × S preferably satisfies the relationship of 50 <Pw × S <420, more preferably 100 <Pw × S <390. When Pw × S is 20 or less, the film formed from the aqueous solution of silyl group-containing PVA has insufficient water resistance, and when Pw × S is 460 or more, silyl group must be added without adding alkali or the like. The contained PVA may not be dissolved in water.

Among vinyl alcohol polymers, when the weight fraction of a polymer whose degree of polymerization exceeds 3 times the weight average degree of polymerization Pw exceeds 25% by weight, the viscosity stability of the aqueous solution of the vinyl alcohol polymer When the aqueous solution containing a vinyl alcohol polymer and an inorganic substance is prepared, a uniform solution may not be obtained.
Among the vinyl alcohol polymers, when the weight fraction of the polymer having a degree of polymerization exceeding 3 times the weight average degree of polymerization Pw exceeds 25% by weight, the viscosity stability of the aqueous solution of the vinyl alcohol polymer is The reason for the decrease is considered as follows.
Among all the monomer units contained in the polymer having a silyl group, the monomer unit having a silyl group is uniformly present. Therefore, as the degree of polymerization of the polymer increases, one molecule of the polymer. The number of monomer units having a silyl group contained in is increased. And as the number of monomer units having a silyl group contained in one polymer molecule increases, the polymer is more susceptible to the influence of the silyl group. That is, a polymer having a high degree of polymerization is more susceptible to silyl groups than a polymer having a low degree of polymerization. Therefore, the vinyl alcohol polymer containing a large amount of the high polymerization degree component contains a large amount of the polymer that is easily affected by the silyl group, and therefore, it is considered that the viscosity stability of the aqueous solution is lowered.

On the other hand, the smaller the degree of polymerization of the polymer, the smaller the number of monomer units having a silyl group contained in one molecule of the polymer. The smaller the number of monomer units having a silyl group contained in one molecule of the polymer, the less likely the polymer is affected by the silyl group. That is, the effect of the silyl group is less likely to appear in a polymer having a lower degree of polymerization than in a polymer having a higher degree of polymerization. Therefore, the vinyl alcohol polymer containing a large amount of low polymerization degree components contains a large amount of a polymer having a small silyl group effect.
The vinyl alcohol polymer of the present invention preferably has a weight fraction of a polymer having a degree of polymerization smaller than ½ times the weight average degree of polymerization Pw of 12% by weight or less. Among vinyl alcohol polymers, when the polymer weight fraction is less than ½ times the weight average degree of polymerization and the weight fraction of the polymer exceeds 12% by weight, the low degree of polymerization with little effect of silyl groups Since many components are contained, when a film containing a vinyl alcohol polymer and an inorganic substance is formed, the water resistance of the film and the binder strength with the inorganic substance of the vinyl alcohol polymer may be reduced. .

The weight average polymerization degree (Pw) and the polymerization degree distribution of the vinyl alcohol polymer can be determined, for example, by GPC-LALLS measurement. That is, by re-saponifying and purifying the silyl group-containing PVA to a saponification degree of 99.5 mol% or more, and then dividing the weight average molecular weight determined by GPC-LALLS by the formula weight 44 of the vinyl alcohol monomer unit. The weight average degree of polymerization is determined. Further, the weight fraction of the polymer having a polymerization degree within a specific range can be determined from the integral polymerization degree distribution obtained from GPC-LALLS measurement.

In the vinyl alcohol polymer of the present invention, the content S (mol%) of the monomer unit having a silyl group is determined from proton NMR of the vinyl ester polymer before saponification. When the proton NMR of the vinyl ester polymer before saponification is measured here, the vinyl ester polymer is purified by reprecipitation with hexane-acetone, and a monomer having an unreacted silyl group from the polymer. Then, after drying at 90 ° C. under reduced pressure for 2 days, it is dissolved in CDCl ₃ solvent and used for analysis.

The vinyl alcohol polymer of the present invention preferably satisfies the following formula (II), and the pH of a 4% aqueous solution thereof is preferably 4-8.
0.1 / 100 ≦ (A−B) / (B) ≦ 50/100 (II)
A: Content of silicon atom in vinyl alcohol polymer (unit: ppm)
B: Content of silicon atom in vinyl alcohol polymer washed with methanol containing sodium hydroxide and then washed with Soxhlet extraction with methanol (unit: ppm)
Here, A and B are measured by ICP emission spectrometry after ashing the measurement sample.

A preferred range of (A-B) / (B) is 0.1 / 100 to 50/100, a more preferred range is 0.3 / 100 to 25/100, and a particularly preferred range is 0.4 / 100. ~ 20/100. When (A-B) / (B) exceeds 50/100, the viscosity stability of the aqueous solution of silyl group-containing PVA decreases, or a uniform solution when preparing an aqueous solution containing the silyl group-containing PVA and an inorganic substance May not be obtained, which is not preferable. In addition, when (AB) / (B) is less than 0.1 / 100, when a film containing silyl group-containing PVA and an inorganic substance is formed, the water resistance of the film and silyl group content The binder strength of PVA with inorganic substances may be reduced, and vinyl alcohol polymers with (A-B) / (B) less than 0.1 / 100 are costly for cleaning during production. Therefore it is not realistic.
Here, in order to obtain the silicon atom content (B), a standard washing method of the vinyl alcohol polymer is a washing operation with methanol containing sodium hydroxide (1 part by weight of vinyl alcohol polymer). In contrast, 10 parts by weight of a methanol solution containing sodium hydroxide was added so that the molar ratio of sodium hydroxide to vinyl alcohol monomer units in the vinyl alcohol polymer was 0.01. The operation of boiling the mixture for 1 hour and then filtering the polymer) is repeated 5 times, followed by Soxhlet extraction with methanol for 1 week. In the above washing method, the washing operation with methanol containing sodium hydroxide and the Soxhlet extraction with methanol are performed until the silicon atom content in the vinyl alcohol polymer is almost unchanged, and this condition is satisfied. In such a range, the number of washing operations with methanol containing sodium hydroxide and the Soxhlet extraction period with methanol may be appropriately increased or decreased.

The silicon atom content (A) of the vinyl alcohol polymer is considered to indicate the content of all silicon atoms contained in the vinyl alcohol polymer. Further, the content (B) of the silicon atom in the vinyl alcohol polymer washed with methanol containing sodium hydroxide and then washed by Soxhlet extraction with methanol is directly incorporated into the main chain of the vinyl alcohol polymer. This is considered to indicate the content of silicon atoms derived from the silyl group-containing monomer.
In determining the silicon atom content (B), the vinyl alcohol polymer is washed with methanol containing sodium hydroxide, and at that time, the siloxane bond (—Si—O—Si—) is broken. At this time, the silyl group-containing monomer that was not directly incorporated into the main chain of the vinyl alcohol polymer and was bonded to the main chain of the vinyl alcohol polymer via a siloxane bond was obtained from the vinyl alcohol polymer. Is removed from the polymer. Therefore, the silicon atom content (B) is considered to indicate the silicon atom content in a state in which the silyl group-containing monomer not directly incorporated in the main chain of the vinyl alcohol polymer is removed. It is done. Therefore, (AB) in the above relational expression 0.1 / 100 ≦ (AB) / (B) ≦ 50/100 represents a silyl group that is not directly introduced into the main chain of the vinyl alcohol polymer. It is considered that the content of the silyl group derived from the monomer unit it has is shown.

When the value of (AB) / (B) in the vinyl alcohol polymer is large, it means that the vinyl alcohol polymer contains many monomer units having an excess silyl group. In the case where the value of (A-B) / (B) in the vinyl alcohol polymer is small, the monomer unit having an excess silyl group that is not directly introduced into the main chain of the vinyl alcohol polymer Means less.
If the value of (A-B) / (B) is too large, a siloxane bond (− between the monomer unit containing an excess silyl group and the silyl group-containing monomer unit incorporated in the main chain) (Si-O-Si-) is formed in large numbers, the molecular mobility of the vinyl alcohol polymer is limited, and the viscosity stability of the aqueous solution of the vinyl alcohol polymer is lowered. It is considered that the interaction between the polymer and the inorganic substance becomes too large, and it may be impossible to obtain a uniform solution when preparing a mixed aqueous solution of the vinyl alcohol polymer and the inorganic substance.

If the value of (AB) / (B) is too small, a siloxane formed between a monomer unit containing an excess silyl group and a silyl group-containing monomer unit incorporated in the main chain Since the ratio of the bond (-Si-O-Si-) is small, the amount of silyl groups contained in the vinyl alcohol polymer is reduced, and the interaction between the vinyl alcohol polymer and the inorganic substance is reduced. Further, when a film containing a vinyl alcohol polymer and an inorganic substance is formed, it is considered that the water resistance of the film and the binder force with the inorganic substance of the vinyl alcohol polymer are reduced.

Furthermore, the vinyl alcohol polymer of the present invention preferably has a 4% aqueous solution with a pH of 4-8. The more preferable range of the pH of the 4% aqueous solution is 4.5 to 7, and the particularly preferable range is 5 to 6.5. When the pH of the 4% aqueous solution is less than 4, the viscosity stability of the vinyl alcohol polymer aqueous solution may decrease. When the pH of the 4% aqueous solution exceeds 8, the vinyl alcohol polymer In the case where a film containing an inorganic material is formed, the water resistance of the film may decrease, which is not preferable.

In the general formula (1) representing the silyl group contained in the vinyl alcohol polymer of the present invention, R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and The group may have a substituent containing oxygen, and m is an integer of 0-2.
Here, examples of the alkyl group having 1 to 5 carbon atoms represented by R ¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, and isobutyl. Group, n-pentyl group, tert-pentyl group, isopentyl group and the like. Examples of the alkoxyl group represented by R ² include methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, tert-butoxy group, pentoxy group, hexyloxy group, octyloxy group, lauryloxy group, and oleyloxy group. In addition, examples of the acyloxyl group include an acetoxy group and a propionyloxy group. These alkoxyl groups or acyloxyl groups may have an oxygen-containing substituent, and examples of the substituent include alkoxyl groups such as a methoxy group and an ethoxy group.

The vinyl alcohol polymer of the present invention is produced by copolymerizing a vinyl ester monomer and a monomer having a silyl group represented by the general formula (1), and saponifying the resulting vinyl ester polymer. can do.

The vinyl alcohol polymer of the present invention comprises a vinyl ester monomer and a monomer having a silyl group represented by the general formula (1), such as 2-mercaptoethanol, n-dodecyl mercaptan, mercaptoacetic acid, 3- It can also be produced by copolymerization in the presence of a thiol compound such as mercaptopropionic acid and saponifying the resulting vinyl ester polymer. By this method, a vinyl alcohol polymer in which a functional group derived from a thiol compound is introduced at the terminal is obtained.

Examples of vinyl ester monomers used in the production of such vinyl alcohol polymers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caprate, vinyl laurate, vinyl stearate, and benzoate. Examples thereof include vinyl acid vinyl, vinyl pivalate, and versatic acid vinyl, and vinyl acetate is particularly preferable.

As a monomer having a silyl group represented by the general formula (1) used for radical copolymerization with a vinyl ester monomer, the following general formula (2)

（式中、Ｒ^１は炭素数１〜５のアルキル基であり、Ｒ^２はアルコキシル基またはアシロキシル基であって、これらの基は酸素を含有する置換基を有していてもよく、ｍは０〜２の整数であり、ｎは０〜４の整数である。）
または下記の一般式（３）

(Wherein R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have a substituent containing oxygen, and m is (It is an integer from 0 to 2, and n is an integer from 0 to 4.)
Or the following general formula (3)

（式中、Ｒ^１は炭素数１〜５のアルキル基であり、Ｒ^２はアルコキシル基またはアシロキシル基であって、これらの基は酸素を含有する置換基を有していてもよく、Ｒ^３は水素原子またはメチル基であり、Ｒ^４は水素原子または炭素数１〜５のアルキル基であり、Ｒ^５は炭素数１〜５のアルキレン基であるかまたは酸素原子もしくは窒素原子を含む２価の炭化水素基であり、ｍは０〜２の整数である。）
で示される化合物を挙げることができる。

(In the formula, R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have a substituent containing oxygen, and 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, R ⁵ is an alkylene group having 1 to ⁵ carbon atoms, or a divalent atom containing an oxygen atom or a nitrogen atom And m is an integer of 0 to 2.)
The compound shown by can be mentioned.

In the general formula (2) and general formula (3), examples of the alkyl group having 1 to 5 carbon atoms represented by R ¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, Examples include sec-butyl group, tert-butyl group, isobutyl group, n-pentyl group, tert-pentyl group, isopentyl group and the like. Examples of the alkoxyl group represented by R ² include methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, tert-butoxy group, pentoxy group, hexyloxy group, octyloxy group, lauryloxy group, and oleyloxy group. In addition, examples of the acyloxyl group include an acetoxy group and a propionyloxy group. These alkoxyl groups or acyloxyl groups may have an oxygen-containing substituent, and examples of the substituent include alkoxyl groups such as a methoxy group and an ethoxy group. Examples of the alkyl group having 1 to 5 carbon atoms represented by R ⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, and an isobutyl group. , N-pentyl group, tert-pentyl group, isopentyl group and the like. Examples of the alkylene group having 1 to 5 carbon atoms represented by R ⁵ include a methylene group, an ethylene group, a dimethylethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group, and an oxygen atom or a nitrogen atom. Examples of the divalent hydrocarbon group to be included include —CH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ —, —CH ₂ CH ₂ NHCH ₂ CH ₂ —, —CH ₂ CH ₂ NHCH ₂ —, —CH ₂ CH ₂ N ( _{CH 3) CH 2 CH 2 -} , - CH 2 CH 2 N (CH 3) CH 2 -, - CH 2 CH 2 OCH 2 CH 2 CH 2 -, - CH 2 CH 2 OCH 2 CH 2 -, - CH 2 CH ₂ OCH ₂ — and the like can be mentioned.

Examples of the monomer represented by the above formula (2) include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, and allyltrimethoxy. Silane, allylmethyldimethoxysilane, allyldimethylmethoxysilane, allyltriethoxysilane, allylmethyldiethoxysilane, allyldimethylethoxysilane, vinyltris (β-methoxyethoxy) silane, vinylisobutyldimethoxysilane, vinylethyldimethoxysilane, vinylmethoxydi Butoxysilane, vinyldimethoxybutoxysilane, vinyltributoxysilane, vinylmethoxydihexyloxysilane, vinyldimethoxyhexyloxysilane, vinyl Rehexyloxy silane, vinyl methoxy dioctyloxy silane, vinyl dimethoxy octyloxy silane, vinyl trioctyloxy silane, vinyl methoxy dilauryl silane, vinyl dimethoxy lauryloxy silane, vinyl methoxy dioleoxy silane, vinyl dimethoxy oleyloxy silane, etc. Is mentioned.
In the above formula (2), when a monomer having a silyl group with n of 1 or more and a vinyl ester monomer are copolymerized, the degree of polymerization of the resulting vinyl ester polymer tends to decrease. In that respect, when vinyltrimethoxysilane is copolymerized with a vinyl ester monomer, it is possible to suppress a decrease in the degree of polymerization of the resulting vinyl ester polymer, and industrial production is easy and inexpensive. Since it can be obtained, it can be preferably used.

Examples of the monomer represented by the above formula (3) include 3- (meth) acrylamide-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane, and 3- (meth) acrylamide-propyl. Tri (β-methoxyethoxy) silane, 2- (meth) acrylamide-ethyltrimethoxysilane, 1- (meth) acrylamide-methyltrimethoxysilane, 2- (meth) acrylamide-2-methylpropyltrimethoxysilane, 2- (Meth) acrylamide-isopropyltrimethoxysilane, N- (2- (meth) acrylamide-ethyl) -aminopropyltrimethoxysilane, (3- (meth) acrylamide-propyl) -oxypropyltrimethoxysilane, 3- (meta ) Acrylamide-propyltria Toxisilane, 2- (meth) acrylamide-ethyltriacetoxysilane, 4- (meth) acrylamide-butyltriacetoxysilane, 3- (meth) acrylamide-propyltripropionyloxysilane, 2- (meth) acrylamide-2-methylpropyl Triacetoxysilane, N- (2- (meth) acrylamide-ethyl) -aminopropyltriacetoxysilane, 3- (meth) acrylamide-propylisobutyldimethoxysilane, 2- (meth) acrylamide-ethyldimethylmethoxysilane, 3- ( Meth) acrylamide-propylmethyldiacetoxysilane, 2- (meth) acrylamide-2-methylpropylhydrogendimethoxysilane, 3- (N-methyl- (meth) acrylamide) -propyltrimethoxy Silane, 2- (N-ethyl- (meth) acrylamide) -ethyltriacetoxysilane, etc. are mentioned.
Among these monomers, 3- (meth) acrylamide-propyltrimethoxysilane and 3- (meth) acrylamide-propyltriacetoxysilane are preferably used because they are relatively easy to manufacture industrially and can be obtained at low cost. 2- (meth) acrylamido-2-methylpropyltrimethoxysilane and 2- (meth) acrylamide-2-methylpropyltriacetoxysilane are remarkably stable to acids or alkalis, It can be preferably used.

Examples of a method for copolymerizing a monomer having a silyl group and a vinyl ester monomer include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these methods, a bulk polymerization method performed without a solvent or a solution polymerization method performed using a solvent such as alcohol is usually employed. When polymerizing by a bulk polymerization method or a solution polymerization method, the weight fraction of a polymer having a polymerization degree exceeding 3 times the weight average polymerization degree Pw is 25% by weight or less, and preferably the polymerization degree is a weight average polymerization. The polymerization method for obtaining the vinyl alcohol polymer of the present invention in which the weight fraction of the polymer smaller than ½ times the degree Pw is 12% by weight or less cannot be generally limited depending on the polymerization conditions and the like. From the viewpoint of suppressing the ratio of the degree component and the low degree of polymerization component, the continuous polymerization method is most preferable. As a continuous polymerization system, for example, a 1-2 tank continuous polymerization system is preferable, and a 1 tank continuous polymerization system is more preferable. In the case of the batch method, the ratio of the high polymerization degree component and the low polymerization degree component changes depending on the polymerization rate of the vinyl ester monomer, etc., and as the polymerization rate increases, the high polymerization degree component and the low polymerization degree component Since the ratio increases, it is preferable to polymerize at a relatively low polymerization rate. A suitable polymerization rate in the batch system cannot be defined unconditionally because it varies depending on the polymerization conditions and the like, but the polymerization rate of the vinyl ester monomer is preferably 10 to 80%, more preferably 15 to 50%. When the copolymerization reaction is carried out using the solution polymerization method, examples of the alcohol used as the solvent include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Examples of the initiator used in the copolymerization reaction include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), 1,1′-azobis (cyclohexane- Azo initiators such as 1-carbonitrile) and 2,2′-azobis (N-butyl-2-methylpropionamide); peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate A well-known initiator is mentioned. Although there is no restriction | limiting in particular about the polymerization temperature at the time of performing a copolymerization reaction, The range of 50 to 180 degreeC is suitable.

When radically copolymerizing a monomer having a silyl group and a vinyl ester monomer, a copolymerizable monomer may be copolymerized as necessary as long as the effects of the present invention are not impaired. It can be polymerized. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene; carboxylic acids such as fumaric acid, maleic acid, itaconic acid, maleic anhydride, and itaconic anhydride; Derivatives thereof; acrylic acid or salts thereof, acrylic esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate; methacrylic acid or salts thereof, methyl methacrylate, ethyl methacrylate, n methacrylate Methacrylic acid esters such as propyl and isopropyl methacrylate; Acrylamide derivatives such as acrylamide, N-methylacrylamide and N-ethylacrylamide; and methacrylamides such as methacrylamide, N-methylmethacrylamide and N-ethylmethacrylamide Body; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether; hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether Allyl ethers such as allyl acetate, propyl allyl ether, butyl allyl ether, hexyl allyl ether; monomers having an oxyalkylene group; isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol Hydroxy group-containing α-olefins such as 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol; Monomers having sulfonic acid groups such as sulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyl Cationic groups such as dimethylamine, vinyloxymethyldiethylamine, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine And the like. The amount of the monomer having a silyl group and a monomer copolymerizable with the vinyl ester monomer varies depending on the purpose and use of the monomer, but all the monomers used for copolymerization are usually used. The ratio based on the monomer is 20 mol% or less, preferably 10 mol% or less.

The vinyl ester polymer obtained by copolymerizing a monomer having a silyl group and a vinyl ester monomer is then saponified in a solvent according to a known method to give a vinyl alcohol polymer. Led.

As a catalyst for the saponification reaction of a vinyl ester polymer, an alkaline substance is usually used. Examples thereof include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and alkali metal alkoxides such as sodium methoxide. Can be mentioned. The amount of the alkaline substance used is preferably in the range of 0.004 to 0.5 in terms of a molar ratio based on the vinyl ester monomer unit in the vinyl ester polymer. It is particularly preferable that the value falls within the range. The saponification catalyst may be added all at once in the early stage of the saponification reaction, or a part thereof may be added in the early stage of the saponification reaction, and the rest may be added and added during the saponification reaction.
Examples of the solvent that can be used for the saponification reaction include methanol, methyl acetate, dimethyl sulfoxide, diethyl sulfoxide, dimethylformamide, and the like. Among these solvents, methanol is preferably used, and in its use, the water content of methanol is preferably 0.001 to 1% by weight, more preferably 0.003 to 0.9% by weight, and particularly preferably 0.005 to 0.005%. It should be adjusted to 0.8% by weight.
The saponification reaction is preferably performed at a temperature of 5 to 80 ° C, more preferably 20 to 70 ° C. The time required for the saponification reaction is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours. The saponification reaction can be carried out by either a batch method or a continuous method. After completion of the saponification reaction, the remaining saponification catalyst may be neutralized as necessary, and examples of usable neutralizers include organic acids such as acetic acid and lactic acid, and ester compounds such as methyl acetate. Can do.

The saponification degree of the vinyl alcohol polymer of the present invention is not particularly limited, but the saponification degree is preferably 80 mol% or more, more preferably 85 mol% or more, and particularly preferably 90 mol% or more. And, when a film containing a vinyl alcohol polymer and an inorganic substance is formed, the optimal saponification degree of the vinyl alcohol polymer is 95 mol% or more from the viewpoint of improving the water resistance of the film. is there.

The vinyl alcohol polymer obtained by the saponification reaction can be washed if necessary, and this operation adjusts the value of (AB) / (B) in the vinyl alcohol polymer described above. Useful as a means.
Usable cleaning liquids include lower alcohols such as methanol, lower fatty acid esters such as methyl acetate, and mixtures thereof. A small amount of water or an alkali or acid is added to these cleaning liquids. May be.

The method employed for washing the vinyl alcohol polymer is the polymerization rate when the vinyl ester monomer and the monomer having a silyl group are copolymerized, and the vinyl ester polymer obtained by the copolymerization. It differs depending on the degree of polymerization, the degree of saponification of the vinyl alcohol polymer obtained by saponifying the vinyl ester polymer, and it is difficult to uniformly define this. As one of the methods, for example, it is obtained by saponifying a copolymer of a vinyl ester monomer and a monomer having a silyl group (vinyl ester polymer) in an alcohol solution, before drying. 1 to 20 times the amount of wet alcoholic polymer impregnated with alcohol or the like, a lower alcohol such as methanol, a lower fatty acid ester such as methyl acetate, or a mixture thereof as a washing solution, The method of washing for about 30 minutes to 10 hours under the temperature condition of the boiling point of the washing liquid can be mentioned.

The vinyl alcohol polymer of the present invention can be stored and transported in a powder state, and can be used in a powder state or dispersed in a liquid when used. The vinyl alcohol polymer can be dissolved in water and used as an aqueous solution. In this case, the vinyl alcohol polymer is dispersed in water and then heated with stirring to obtain a uniform aqueous solution. can do. In this case, a uniform aqueous solution can be obtained without adding an alkali such as sodium hydroxide to water.

The vinyl alcohol polymer of the present invention can be dissolved in water to prepare an aqueous solution without adding an alkali or acid such as sodium hydroxide; the aqueous solution has excellent viscosity stability. The film obtained from the aqueous solution is excellent in water resistance; the binder strength with the inorganic substance is excellent; the film obtained from the mixture with the inorganic substance is excellent in water resistance; Taking advantage of the properties, it can be used as a coating agent. The coated product obtained by coating the base material with the coating agent containing the vinyl alcohol polymer of the present invention is suitably used for an ink jet recording material and a heat sensitive recording material.

When the inkjet recording material is produced by applying a coating agent containing the vinyl alcohol polymer of the present invention to a substrate, the vinyl alcohol polymer of the present invention is suitably used as a binder for the ink receiving layer. At that time, the vinyl alcohol polymer of the present invention may be used alone or in combination with other water-soluble or water-dispersible resins. Other water-soluble resins that can be used in combination with the vinyl alcohol polymer of the present invention include albumin, gelatin, casein, starch, cationized starch, arabic rubber, polyamide resin, melamine resin, poly (meth) acrylamide, and polyvinylpyrrolidone. , Sodium poly (meth) acrylate, anion-modified PVA, sodium alginate, water-soluble polyester, and cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose (CMC). Examples of water-dispersible resins include SBR latex and NBR. Examples include latex, vinyl acetate emulsion, ethylene / vinyl acetate copolymer emulsion, (meth) acrylic ester emulsion, and vinyl chloride emulsion. But it is not limited to, et al.

When the vinyl alcohol polymer of the present invention is used as a binder for an ink receiving layer in an ink jet recording material, the filler used in the ink receiving layer includes precipitated silica, gel-like silica, vapor phase silica, colloidal silica, and colloidal. Alumina, aluminum hydroxide, pseudoboehmite, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, satin white, organic pigments and the like are exemplified, but not limited thereto. Here, the ratio between the vinyl alcohol polymer and the filler is not particularly limited, but it is usually preferable that the weight ratio of the vinyl alcohol polymer / filler is in the range of 5/100 to 100/100. More preferably, it is in the range of 10/100 to 80/100, and particularly preferably in the range of 15/100 to 60/100.

Further, when the polyvinyl alcohol polymer of the present invention is used as a binder of an ink receiving layer in an ink jet recording material, a cationic resin can be used in combination as an ink fixing agent. The cationic resin is a monomer, oligomer, or polymer having a primary to tertiary amine or quaternary ammonium salt that dissociates and exhibits cationic properties when dissolved in water, and is preferably an oligomer or polymer. Specific examples include dimethylamine / epichlorohydrin polycondensate, acrylamide / diallylamine copolymer, polyvinylamine copolymer, dimethyldiallylammonium chloride polymer, polyethyleneimine, etc., but are not limited to these examples. It is not something.

Any conventionally known transparent or opaque support substrate can be used as the base material used in the above-described ink jet recording material. Examples of the transparent support substrate include polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polycarbonate, polyimide, cellophane, celluloid and other films, sheets, and highly transparent paper. Examples of the opaque support substrate include general paper, pigment-coated paper, cloth, wood, metal plate, synthetic paper, and a synthetic resin film or sheet subjected to opacification treatment.

Examples of the method for producing an ink jet recording material by coating the base material with the coating agent containing the vinyl alcohol polymer of the present invention include the vinyl alcohol polymer and, if necessary, a filler, an ink fixing agent, etc. Is dissolved or dispersed in an aqueous medium to prepare a coating agent, and the obtained coating agent is used with a conventionally known size press, air knife coater, roll coater, bar coater, blade coater, curtain coater, cast coater, etc. The method of applying to a base material is mentioned. Here, water is preferably used as the aqueous medium. As the aqueous solvent, an aqueous solution in which a water-soluble organic solvent, acid, base, salts and the like are dissolved can also be used. The base material is coated with the coating agent containing the vinyl alcohol polymer of the present invention, and the vinyl alcohol polymer is impregnated in the base material, or the vinyl alcohol base is coated on one or both sides of the base material. By forming a coating layer made of a polymer, an ink jet recording material excellent in water resistance and binder strength with an inorganic substance can be obtained.

When a thermosensitive recording material is produced by applying a coating agent containing the vinyl alcohol polymer of the present invention to a substrate, the vinyl alcohol polymer of the present invention comprises an overcoat layer, a thermosensitive coloring layer, and an undercoat layer. Used for. Among these, the vinyl alcohol polymer of the present invention is suitably used as a binder for the overcoat layer and the thermosensitive coloring layer.

By using the vinyl alcohol polymer of the present invention for the overcoat layer, a heat-sensitive recording material excellent in water resistance and plasticizer resistance can be obtained. When the vinyl alcohol polymer of the present invention is used for an overcoat layer, the vinyl alcohol polymer is generally used in combination with a crosslinking agent. As the crosslinking agent used here, aldehyde compounds such as glyoxal and glutaraldehyde, zirconium compounds such as ammonium zirconium carbonate, titanium compounds such as titanium lactate, colloidal silica, epoxy compounds such as polyamidoamine epichlorohydrin, and polyoxazoline are suitable. Used for. In addition, the vinyl alcohol polymer of the present invention can be used in combination with known polymers or polymer dispersions as shown below as long as the water resistance and plasticizer resistance are not impaired. Specific examples of the polymer or polymer dispersion include starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, polyvinyl alcohol, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / Acrylate ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin Water-soluble polymers such as casein; polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate Over DOO, emulsion and ethylene / vinyl acetate copolymers, styrene / butadiene copolymer, styrene / butadiene / latex such as acrylic copolymer.

When the vinyl alcohol polymer of the present invention is used in an overcoat layer in a heat-sensitive recording material, the filler used in combination with the vinyl alcohol polymer includes kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide. Diatomaceous earth, precipitated silica, gel silica, colloidal silica, aluminum oxide, aluminum hydroxide, synthetic aluminum silicate, synthetic magnesium silicate, polystyrene fine particles, polyvinyl acetate fine particles, urea-formalin resin fine particles, and the like. In the overcoat layer, the preferred addition amount of these fillers is 20% by weight or more of the total components of the overcoat layer. When the addition amount is less than 20% by weight, water resistance, oil resistance, plasticizer resistance and the like may be deteriorated.
The coating amount of the overcoat layer is appropriately selected as long as thermal conduction from the thermal head of the thermal recording apparatus to the thermal coloring layer of the thermal recording material is not inhibited, but is usually 1 to 10 g / m ² , preferably 2 to 2. 7 g / m ² .

By using the vinyl alcohol polymer of the present invention for the thermosensitive coloring layer, a thermosensitive recording material excellent in water resistance and plasticizer resistance can be obtained. The thermal dye used in the thermal coloring layer is not particularly limited as long as it is used for a general pressure-sensitive recording material or a thermal recording material. Specific examples of the thermal dye include 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-ethylcarbazole-3) -Yl) -5-dimethylaminophthalide and other triarylmethane compounds; 4,4'-bisdimethylaminobenzhydrin benzyl ether, N-halophenylleucooramine and other diphenylmethane compounds; rhodamine B-anilino Lactam, 3-diethylamino-7-benzylaminofluorane, 3-diethylamino-7-butylamino Luolan, 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-nitrobenzoylro Thiazine compounds such as Comethylene Blue; spiro compounds such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methylnaphtho- (3-methoxy-benzo) -spiropyran, etc. Is mentioned. These thermal dyes are appropriately selected depending on the use of the thermal recording material, and are used alone or as a mixture of two or more.

Further, as the color developer used in the thermosensitive coloring layer, a phenol derivative and an aromatic carboxylic acid derivative are preferable, and bisphenols are particularly preferable. Specific examples of the phenol derivative include 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)- Examples include 2-ethyl-hexane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, and dihydroxydiphenyl ether. Specific examples of the aromatic carboxylic acid derivative include p-hydroxybenzoic acid, ethyl p-hydroxybenzoate, butyl p-hydroxybenzoate, 3,5-di-tert-butylsalicylic acid, 3,5-di-α- Examples thereof include methylbenzyl salicylic acid and polyvalent metal salts of the above carboxylic acids.

When the vinyl alcohol polymer of the present invention is used in a heat-sensitive color developing layer, the vinyl alcohol polymer of the present invention is a known polymer or the like shown below within a range not impairing water resistance and plasticizer resistance. It can be used in combination with a polymer dispersion. Specific examples of the polymer or polymer dispersion include starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, arabic gum, polyvinyl alcohol, acrylic acid (or methacrylic acid) ester. Alkaline salt of copolymer, polyvinylpyrrolidone, acrylamide (or methacrylamide) / acrylic acid (or methacrylic acid) ester copolymer, alkali salt of styrene / maleic anhydride copolymer, isobutylene / maleic anhydride copolymer Alkali salts, alkali salts of diisobutylene / maleic anhydride copolymer, water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, casein; polyvinyl acetate, polyurea , Polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer emulsion, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer Examples include latex such as coalescence.

Examples of the lubricant used in the thermosensitive coloring layer include higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, paraffin wax, microcrystalline wax and the like.

The filler used in the thermosensitive coloring layer includes kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, precipitated silica, gel silica, colloidal silica, aluminum oxide, aluminum hydroxide, synthetic silica. Examples thereof include aluminum oxide, synthetic magnesium silicate, polystyrene fine particles, polyvinyl acetate-based fine particles, urea-formalin resin fine particles, and the like. In the thermosensitive coloring layer, the preferred amount of these fillers is 20% by weight or more of the total components of the thermosensitive coloring layer.

When producing a heat-sensitive recording material by coating the base material with the coating agent containing the vinyl alcohol polymer of the present invention, a conventionally known air knife method, plate method, gravure method, roll coater method, spray method, dip method Methods such as the law, bar method and extrusion method can be used.

In addition, the vinyl alcohol polymer of the present invention can be used in various applications utilizing the function of a functional group such as a hydroxyl group, a vinyl ester group, and a silyl group. , Textile processing agents, dyes, glass fiber coating agents, metal surface coating agents, coating agents such as anti-fogging agents, adhesives such as wood, paper, aluminum foil, plastics, nonwoven fabric binders, fibrous binders, gypsum boards and Binders for building materials such as fiberboard, thickeners for various emulsion adhesives, additives for urea resin adhesives, additives for cement and mortar, various adhesives such as hot melt adhesives, pressure sensitive adhesives, Dispersants for emulsion polymerization of various ethylenically unsaturated monomers such as ethylene, vinyl acetate and vinyl chloride, stabilizers for pigment dispersion such as paints and adhesives, vinyl chloride and vinyl chloride Molding of dispersion stabilizers for suspension polymerization of various ethylenically unsaturated monomers such as redene, styrene, (meth) acrylic acid, vinyl acetate, fibers, films, sheets, pipes, tubes, water-soluble fibers, and temporary coatings And additives for synthetic resins, such as additives for hydrophilicity to hydrophobic resins, composite fibers, films and other additives for molded products, soil improvers, and soil stabilizers.
The vinyl acetal polymer obtained by acetalizing the vinyl alcohol polymer of the present invention with an aldehyde compound such as acetaldehyde or butyraldehyde is a safety glass interlayer film, ceramic binder, ink dispersant, photosensitive material. It is useful for such applications.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. In the following examples and comparative examples, “parts” and “%” mean weight basis unless otherwise specified.

I. Silyl group-containing vinyl alcohol polymer PVA was produced by the following method, and the degree of saponification, the content of monomer units having a silyl group, the weight average degree of polymerization, and the content of silicon atoms were determined.

[Saponification degree of PVA]
The degree of saponification of PVA was determined by the method described in JIS-K6726.

[Content of monomer unit having silyl group contained in PVA]
The vinyl ester polymer before saponification was purified by reprecipitation with hexane-acetone to completely remove the monomer having unreacted silyl groups from the polymer, followed by drying at 90 ° C. under reduced pressure for 2 days. Using a sample dissolved in a CDCl ₃ solvent as a measurement sample, the content of the monomer unit having a silyl group contained in PVA was determined using a 500 MHz proton NMR measurement apparatus (JEOL GX-500).

[Weight average polymerization degree of PVA]
A sample obtained by saponifying PVA to a saponification degree of 99.5 mol% or more was used as a sample, and a weight average molecular weight was determined by a LALLS (low angle laser light scattering photometer) method. Measurement was performed at 23 ° C. using a GPC224 type gel permeation chromatograph (Waters) connected with three TSK-gel-GMPWxL (manufactured by Tosoh Corporation) as a column. In the measurement, 0.08 M Tris buffer (pH 7.9) was used as a solvent, and an R-401 differential refractometer, 8X (Waters) was used as a detector. In order to obtain the absolute molecular weight of the sample, a KMX-6 type low angle laser light scattering photometer (Chromatix) is connected for measurement, and the weight average molecular weight obtained as a result of the measurement is expressed as a formula weight 44 of vinyl alcohol monomer units. The value obtained by dividing by was used as the weight average degree of polymerization. The weight fraction of the polymer having a degree of polymerization exceeding 3 times the weight average degree of polymerization and the weight fraction of a polymer having a degree of polymerization smaller than ½ times the weight average degree of polymerization are obtained by the above measurement. Obtained from the obtained integral polymerization degree distribution.

[Content of silicon atom contained in PVA]
The content of silicon atoms contained in PVA was determined using an ICP emission analyzer IRIS AP manufactured by Jarrel Ashe according to the method described above.

PVA1
A polymerization tank equipped with a stirrer, a temperature sensor, a chemical addition line, a polymerization liquid take-out line and a reflux condenser is charged with 2500 parts of vinyl acetate, 1656 parts of methanol, and 752 parts of a methanol solution containing 2% by weight of vinyltrimethoxysilane (VMS). After charging and replacing the system with nitrogen under stirring, the internal temperature was raised to 60 ° C. To this system, 20 parts of methanol containing 0.1 part of 2,2′-azobis (4-methoxy-2,4-dimethoxyvaleronitrile) (AMV) was added to initiate the polymerization reaction. From the start of polymerization, polymerization was carried out while adding 100 parts of a methanol solution containing 2% by weight of VMS. At the same time, a methanol solution containing 0.13% by weight of AMV was added into the system at a rate of 23 parts / hour, and a polymerization reaction was carried out for 4 hours until the solid content concentration in the system reached 25%. From the time when the concentration of solids in the system reaches 25%, vinyl acetate 625 parts / hour, methanol 414 parts / hour, methanol solution 188 parts / hour containing 2% VMS, and AMV 0.13% While the methanol solution was added to the system at a rate of 23 parts / hour, the polymerization reaction was carried out while continuously taking out the polymerization solution from the system so that the liquid level in the polymerization tank was constant. When 4 hours had elapsed from the start of addition, the polymerization solution was recovered. By introducing methanol vapor into the recovered liquid, unreacted vinyl acetate monomer was driven off to obtain a methanol solution containing 40% vinyl ester polymer. The solid content concentration in the system at the time when the polymerization solution was recovered was 25%.
For a methanol solution containing 40% of this vinyl ester polymer, the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.02, and the solid content concentration of the vinyl ester polymer is 35 wt. %, Methanol and a methanol solution containing 10% by weight of sodium hydroxide were added in this order under stirring, and the saponification reaction was started at 40 ° C.
Immediately after the saponification reaction has progressed, a gelled product is formed and removed from the reaction system and pulverized. Then, methyl acetate is added to the pulverized product when 1 hour has elapsed since the start of the saponification reaction. The PVA neutralized and swollen with methanol was obtained. To the PVA swollen with methanol, 6 times the amount of methanol (six times the bath ratio) of methanol was added, washed under reflux for 1 hour, and then dried at 65 ° C. for 16 hours to obtain PVA.
The obtained PVA had a vinyltrimethylsilane unit content of 0.50 mol%, a saponification degree of 98.5 mol%, and a weight average polymerization degree of 580. Moreover, the value of (AB) / (B) calculated | required according to the analysis method of silicon atom content contained in the above-mentioned PVA is 10.9 / 100, and pH of 4% PVA aqueous solution is 6.0. there were.

PVA2
PVA2 was prepared in the same manner as PVA1 except that the amounts of vinyl acetate and methanol, the amount of monomer having a silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction were changed as shown in Table 1. Was synthesized. Table 4 shows the results of analysis on the obtained PVA.

PVA3
In a polymerization tank 1 equipped with a stirrer, a temperature sensor, a chemical addition line, a polymerization liquid take-out line and a reflux condenser, and a polymerization tank 2 equipped with the same equipment, 2000 parts of vinyl acetate, 2352 parts of methanol, vinyltrimethoxysilane ( After adding 600 parts of a methanol solution containing 2% by weight of VMS) and replacing the system with nitrogen under stirring, the internal temperature was raised to 60 ° C. 20 parts of a methanol solution containing 0.05 part of 2,2′-azobis (4-methoxy-2,4-dimethoxyvaleronitrile) (AMV) is added to the polymerization tank 1 and the polymerization tank 2, respectively, and the polymerization reaction is carried out. Started. Polymerization was carried out while adding 80 parts of a methanol solution containing 2% by weight of VMS at a rate of 150 parts / hour from the start of polymerization to each polymerization tank. At the same time, a methanol solution containing 0.13% by weight of AMV was added to the polymerization tank 1 and the polymerization tank 2 at a rate of 4 parts / hour, and the polymerization reaction was continued for 4 hours until the solid content in the system reached 10%. went. Thereafter, the polymerization tank 1 was charged with 500 parts / hour of vinyl acetate, 588 parts / hour of methanol, 150 parts / hour of a methanol solution containing 2% of VMS, and 4 parts / hour of a methanol solution containing 0.13% of AMV. In the polymerization tank 2, the polymerization liquid is continuously taken out from the polymerization tank 1 and fed to the polymerization tank 2 so that the liquid level in the polymerization tank becomes constant. The polymerization reaction was carried out while continuously taking out the polymerization solution so that the liquid level inside was constant. In addition, when feeding the polymerization liquid taken out from the polymerization tank 1 to the polymerization tank 2, methanol containing 0.13% of AMV was added at a rate of 8 parts / hour.
When 4 hours have elapsed from the start of the feed, when the solid content in the polymerization tank 1 is 10% and the solid content in the polymerization tank 2 is 24%, the polymerization solution is recovered from the polymerization tank 2 and recovered. By introducing methanol vapor into the resulting liquid, unreacted vinyl acetate monomer was driven off to obtain a methanol solution containing 40% vinyl ester polymer.
For a methanol solution containing 40% of this vinyl ester polymer, the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.02, and the solid content concentration of the vinyl ester polymer is 35 wt. %, Methanol and a methanol solution containing 10% by weight of sodium hydroxide were added in this order under stirring, and the saponification reaction was started at 40 ° C.
Immediately after the saponification reaction has progressed, a gelled product is formed and removed from the reaction system and pulverized. Then, methyl acetate is added to the pulverized product when 1 hour has elapsed since the start of the saponification reaction. The PVA neutralized and swollen with methanol was obtained. To the PVA swollen with methanol, 6 times the amount of methanol (six times the bath ratio) of methanol was added, washed under reflux for 1 hour, and then dried at 65 ° C. for 16 hours to obtain PVA.
The obtained PVA had a vinyltrimethylsilane content of 0.50 mol%, a saponification degree of 98.2 mol%, and a weight average polymerization degree of 590. Moreover, the value of (AB) / (B) calculated | required according to the analysis method of silicon atom content contained in the above-mentioned PVA is 9.6 / 100, and pH of 4% PVA aqueous solution is 6.0. there were.

PVA4
Except for changing the amount of vinyl acetate and methanol, the amount of monomer having a silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction, the conditions for the saponification reaction, etc. as shown in Table 2, PVA4 was synthesized by the same method. Table 4 shows the results of analysis on the obtained PVA.

PVA5
A 6 L separable flask equipped with a stirrer, a temperature sensor, a dropping funnel and a reflux condenser was charged with 1050 parts of vinyl acetate, 2056 parts of methanol, and 394 parts of a methanol solution containing 2% by weight of vinyltrimethoxysilane. Was replaced with nitrogen, and the internal temperature was raised to 60 ° C. To this system, 20 parts of methanol containing 1.3 parts of 2,2′-azobisisobutyronitrile was added to initiate the polymerization reaction. The polymerization reaction was carried out for 4 hours while adding 30 parts of a methanol solution containing 2% by weight of vinyltrimethoxysilane to the system from the start of the polymerization, and the polymerization reaction was stopped at that time. The solid concentration in the system at the time when the polymerization reaction was stopped was 15.2%. Subsequently, methanol vapor was introduced into the system to drive off unreacted vinyl acetate monomer, thereby obtaining a methanol solution containing 40% vinyl ester polymer.
For a methanol solution containing 40% of this vinyl ester polymer, the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.02, and the solid content concentration of the vinyl ester polymer is 35 wt. %, Methanol and a methanol solution containing 10% by weight of sodium hydroxide were added in this order under stirring, and the saponification reaction was started at 40 ° C.
Immediately after the saponification reaction has progressed, a gelled product is formed and removed from the reaction system and pulverized. Then, methyl acetate is added to the pulverized product when 1 hour has elapsed since the start of the saponification reaction. The PVA neutralized and swollen with methanol was obtained. To the PVA swollen with methanol, 6 times the amount of methanol (six times the bath ratio) of methanol was added, washed under reflux for 1 hour, and then dried at 65 ° C. for 16 hours to obtain PVA.
The obtained PVA had a vinyltrimethylsilane content of 0.50 mol%, a saponification degree of 98.5 mol%, and a weight average polymerization degree of 560. Moreover, the value of (AB) / (B) calculated | required according to the analysis method of silicon atom content contained in the above-mentioned PVA is 10.9 / 100, and pH of 4% PVA aqueous solution is 6.0. there were.

PVA 6-9
Except for changing the amount of vinyl acetate and methanol, the type and amount of monomer having silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction, the conditions for the saponification reaction, etc. as shown in Table 3. Various PVA (PVA6-9) was synthesize | combined by the method similar to PVA5. Table 4 shows the results of analysis on the obtained PVA.

PVA10
Saponification is performed by adding a methanol solution containing 10% by weight of sodium hydroxide to the vinyl ester polymer so that the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.01. PVA10 was synthesized in the same manner as PVA1 except that the reaction was performed. Table 4 shows the results of analysis on the obtained PVA.

PVA11
Saponification is performed by adding a methanol solution containing 10% by weight of sodium hydroxide to the vinyl ester polymer so that the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.01. PVA11 was synthesized in the same manner as PVA2 except that the reaction was performed. Table 4 shows the results of analysis on the obtained PVA.

PVA12
PVA12 was synthesized by the same method as PVA2, except that the washing operation with methanol was omitted. Table 4 shows the results of analysis on the obtained PVA.

PVA13
PVA13 was synthesized in the same manner as PVA2 except that a washing operation by Soxhlet extraction using methanol was added before neutralizing the PVA obtained by the saponification reaction with methyl acetate. Table 4 shows the results of analysis on the obtained PVA.

PVA14
PVA2 except that neutralization was performed using acetic acid having a molar number of 5 times that of sodium hydroxide used in the saponification reaction instead of methyl acetate, and further washing with methanol (bath ratio 6 times) was performed at room temperature for 1 hour. PVA14 was synthesized by the same method. Table 4 shows the results of analysis on the obtained PVA.

PVA15
PVA15 was synthesized by the same method as PVA2 except that neutralization with methyl acetate was not performed, and washing with methanol (bath ratio 6 times) was performed at room temperature for 1 hour. Table 4 shows the results of analysis on the obtained PVA.

PVA 16 and 17
PVA16 was prepared in the same manner as PVA1 except that the amounts of vinyl acetate and methanol, the amount of monomer having a silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction were changed as shown in Table 1. And 17 were synthesized. Table 4 shows the results of analysis on the obtained PVA.

PVA 18 and 19
Except for changing the amount of vinyl acetate and methanol, the amount of monomer having a silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction, the conditions for the saponification reaction, etc. as shown in Table 2, PVA 18 and 19 were synthesized by the same method. Table 4 shows the results of analysis on the obtained PVA.

PVA 20 and 21
Except for changing the amount of vinyl acetate and methanol, the type and amount of monomer having silyl group, the amount of polymerization initiator used, the conditions for the polymerization reaction, the conditions for the saponification reaction, etc. as shown in Table 3. PVA20 and 21 were synthesized by the same method as PVA5. Table 4 shows the results of analysis on the obtained PVA.

PVA22
Saponification is performed by adding a methanol solution containing 10% by weight of sodium hydroxide to the vinyl ester polymer so that the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.01. PVA22 was synthesized in the same manner as PVA16 except that the reaction was performed. Table 4 shows the results of analysis on the obtained PVA.

PVA23
Saponification is performed by adding a methanol solution containing 10% by weight of sodium hydroxide to the vinyl ester polymer so that the molar ratio of sodium hydroxide to vinyl acetate units in the vinyl ester polymer is 0.01. PVA23 was synthesized in the same manner as PVA17 except that the reaction was performed. Table 4 shows the results of analysis on the obtained PVA.

Examples 1-15
About PVA1-PVA15, the viscosity stability of PVA aqueous solution, the water resistance of a film | membrane, the water resistance of the film | membrane containing an inorganic substance, and the binder power of PVA and an inorganic substance were evaluated with the following evaluation method. The results are shown in Table 5.

Comparative Examples 1-8
About PVA16-PVA23, the viscosity stability of PVA aqueous solution, the water resistance of a film | membrane, the water resistance of the film | membrane containing an inorganic substance, and the binder force of PVA and an inorganic substance were evaluated with the following evaluation method. The results are shown in Table 5.

[Viscosity stability of PVA aqueous solution]
A 9% PVA aqueous solution was prepared and allowed to stand in a 10 ° C. constant temperature bath, and the viscosity immediately after the temperature of the PVA aqueous solution reached 10 ° C. and the viscosity after 7 days were measured. A value obtained by dividing the viscosity after 7 days by the viscosity immediately after the temperature of the aqueous PVA solution reached 10 ° C. (after 7 days / immediately) was determined and determined according to the following criteria.
A: Less than 2.5 times.
B: 2.5 times or more and less than 3.5 times.
C: Although it is 3.5 times or more, PVA is not gelled.
D: PVA loses fluidity and gels.

[Water resistance of film]
A PVA aqueous solution having a concentration of 4% was prepared and cast at 20 ° C. to obtain a film having a thickness of 40 μm. The obtained film was heat-treated at 120 ° C. for 10 minutes, and then cut into a size of 10 cm in length and 10 cm in width to prepare a test piece. This test piece was immersed in distilled water at 20 ° C. for 30 minutes, then taken out (collected), the water adhering to the surface was wiped off with gauze, and the weight at the time of water swelling was measured. The test piece whose weight during water swelling was measured was dried at 105 ° C. for 16 hours, and then the weight during drying was measured. Here, a value obtained by dividing the weight at the time of water swelling by the weight at the time of drying was obtained, and this was taken as the degree of swelling (times), and the determination was made according to the following criteria.
A: Less than 4.0 times.
B: 4.0 times or more and less than 5.0 times.
C: 5.0 times or more and less than 9.0 times.
D: It is 9.0 times or more, or the immersed test piece cannot be collected.

[Water resistance of coatings containing inorganic substances]
A 20% aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries: Snowtex ST-O) was prepared so that a PVA aqueous solution with a concentration of 4% was prepared and the weight ratio of the solid content basis of PVA / colloidal silica was 100/10. Then, the film was cast at 20 ° C. to obtain a film having a thickness of 40 μm.
The obtained film was heat treated at 120 ° C. for 30 minutes, and then cut into a size of 10 cm in length and 10 cm in width to prepare a test piece. This test piece was immersed in distilled water at 20 ° C. for 24 hours, then taken out (collected), the water adhering to the surface was wiped off with gauze, and the weight at the time of water swelling was measured. The test piece whose weight during water swelling was measured was dried at 105 ° C. for 16 hours, and then the weight during drying was measured. Here, a value obtained by dividing the weight at the time of water swelling by the weight at the time of drying was obtained, and this was taken as the degree of swelling (times), and the determination was made according to the following criteria.
A: Less than 5.0 times.
B: 5.0 times or more and less than 8.0 times.
C: 8.0 times or more and less than 12.0 times.
D: It is 12.0 times or more, or the immersed test piece cannot be collected.

[Evaluation of binder strength with inorganic substances]
Silica (manufactured by Mizusawa Chemical Co., Ltd .: Mizukasil P78D) and 0.2% of a dispersant (manufactured by Toagosei Chemical Industry Co., Ltd .: Aron T40) are dispersed in water with a homogenizer, and a silica 20% aqueous dispersion Prepared. To this silica water dispersion, a PVA aqueous solution adjusted to 10% was added so that the weight ratio based on the solid content of silica / PVA was 100/35, and a necessary amount of water was added to adjust the concentration to 15%. A silica-dispersed PVA aqueous solution was obtained.
The obtained silica-dispersed PVA aqueous solution was applied to the surface of the fine paper with a basis weight of 60 g / m ² using a wire bar. Thereafter, the quality paper was dried at 100 ° C. for 3 minutes using a hot air dryer to obtain a sample for evaluation. The coating amount on high-quality paper (sample for evaluation) after drying was 11 g / m ² .
About the sample for evaluation, using an IGT printability tester, measurement is performed at a printing pressure of 25 kg / cm ² , and the surface is printed with the printing speed (cm / sec) when the surface of the sample for evaluation is peeled off. The strength of the binder was evaluated according to the following criteria. In the measurement using an IGT printability tester, IGT pick oil M (manufactured by Dainippon Ink & Chemicals, Inc.) was used and a spring drive B mechanism was adopted.
A: 260 cm / sec or more.
B: 220 cm / sec or more and less than 260 cm / sec.
C: 180 cm / sec or more and less than 220 cm / sec.
D: Less than 180 cm / sec.

From the results shown in Table 5, the vinyl alcohol polymer corresponding to the present invention has excellent balance between the viscosity stability of the PVA aqueous solution, the water resistance of the film, the water resistance of the film containing an inorganic substance, and the binder strength with the inorganic substance. (Examples 1 to 15). In particular, the vinyl alcohol polymer satisfies the above formula (II) [0.1 / 100 ≦ (AB) / (B) ≦ 50/100], and the pH of a 4% aqueous solution of the vinyl alcohol polymer. Satisfying the conditions of 4 to 8, and the weight fraction of the polymer having a polymerization degree smaller than ½ times the weight average polymerization degree Pw in the vinyl alcohol polymer is 12% by weight or less. In this case, the balance of various physical properties is further improved (Examples 1 to 7, and Examples 10 and 11).
In addition, the vinyl alcohol polymer corresponding to the present invention is suitable for a binder of an ink receiving layer in an ink jet recording material because it has excellent water resistance of a film containing an inorganic substance and a binder power with an inorganic substance. I understand.
On the other hand, a vinyl alcohol polymer having Pw (weight average polymerization degree of vinyl alcohol polymer) × S (content of monomer unit having a silyl group) of 20 or less is water resistance of a film containing an inorganic substance, In addition, the binder strength with inorganic substances was not sufficient (Comparative Example 6), and a vinyl alcohol polymer having Pw × S of 460 or more could not be evaluated because it was not completely dissolved in water (Comparative Example 5). ).
Among vinyl alcohol polymers, a vinyl alcohol polymer having a polymerization degree exceeding 3 times the weight average polymerization degree Pw and a weight fraction exceeding 25% by weight contains viscosity stability of an aqueous solution and contains an inorganic substance. It can be seen that the water resistance of the coating film and the binder strength with the inorganic substance are not sufficient (Comparative Examples 3 and 4).
It can be seen that the vinyl alcohol polymer containing no silyl group-containing monomer does not have sufficient water resistance of a film containing an inorganic substance and binder strength with the inorganic substance (Comparative Examples 1, 2, 7 and 8). .

II. Inkjet recording paper An inkjet recording paper was produced by the following method, and the surface strength of the ink receiving layer and the printing quality and water resistance when printing on the recording material using an inkjet printer were evaluated.

Example 16
A 10% aqueous solution of PVA1 was prepared. Further, silica (produced by Grace: Thyroid 162) was dispersed in water with a homogenizer to prepare a 20% aqueous dispersion of silica. A 10% concentration PVA1 aqueous solution and a cationic polymer (manufactured by Sumitomo Chemical Co., Ltd .: Sumire's Resin 1001) so that the weight ratio of silica / PVA / cationic polymer based on the solid content is 100/55/3. And a required amount of water was added to obtain a coating solution for an ink receiving layer having a solid concentration of 14%.
As a result of measurement using a BL type viscometer under the conditions of 40 ° C. and 30 rpm, the viscosity of the coating solution immediately after preparation was 480 mPa · s. The viscosity of the coating solution after being allowed to stand at 40 ° C. for 1 week was 1.92 times immediately after preparation and hardly changed, and the viscosity stability of the coating solution was good.
Coating the ink receiving layer coating liquid prepared above on the surface of a base paper (basis weight: 60 g / m ² fine paper) using a wire bar coater at a rate of 11 g / m ^{2 in} terms of solid content And dried for 3 minutes with a hot air dryer at 100 ° C. to obtain an ink jet recording paper.

[Surface strength of ink receiving layer]
The obtained inkjet recording paper was measured at a printing pressure of 25 kg / cm ² using an IGT printability tester, and the printing speed (cm / sec) when the surface of the inkjet recording paper was peeled off was determined. The surface strength of the ink receiving layer was evaluated according to the following criteria. In the measurement using an IGT printability tester, IGT pick oil M (manufactured by Dainippon Ink & Chemicals, Inc.) was used and a spring drive B mechanism was adopted.
A: 260 cm / sec or more.
B: 220 cm / sec or more and less than 260 cm / sec.
C: 180 cm / sec or more and less than 220 cm / sec.
D: Less than 180 cm / sec.

[Print quality]
A black ink was solid printed on an inkjet recording paper using an inkjet printer (manufactured by EPSON: PM-3300C), and the print quality was visually determined according to the following criteria.
A: The recording density was uniform throughout the printed area, and a good image was obtained.
B: Spots of recording density were observed only slightly, but the image was not greatly affected.
C: Recording density spots were partially generated, and the image quality was impaired.
D: Recording density spots were generated throughout, and the image quality was significantly impaired.

[water resistant]
Black ink solid printing was performed on an inkjet recording paper using an inkjet printer (manufactured by EPSON: PM-3300C). 1 mL of water was dropped on the boundary portion of the solid printing using a syringe and allowed to stand for 24 hours, and then the degree of printing bleeding was visually determined according to the following criteria.
A: No bleeding is observed at all.
B: Slight bleeding was observed.
C: Bleeding partially spread.
D: The blot spread to the whole when water was dropped.

Examples 17-30
An ink jet recording paper was produced in the same manner as in Example 16 except that PVA having a silyl group shown in Table 6 was used instead of the PVA having a silyl group used in Example 16, and the ink receiving layer was used. And the printing quality and water resistance when printing on the recording material using an ink jet printer were evaluated. The results are also shown in Table 6.

Comparative Examples 9-16
An inkjet recording paper was produced in the same manner as in Example 16 except that PVA shown in Table 6 was used instead of PVA having a silyl group used in Example 16, and the surface strength of the ink receiving layer was The printing quality and water resistance when printing on the recording material using an inkjet printer were evaluated. The results are also shown in Table 6.

From the results in Table 6, when an ink jet recording paper is produced using the vinyl alcohol polymer corresponding to the present invention as a binder for the ink receiving layer, the surface strength of the ink receiving layer of the recording paper is good, and It can be seen that the printing quality and water resistance when printing on the recording paper using an inkjet printer are good (Examples 16 to 30).
In particular, the vinyl alcohol polymer used as the binder of the ink receiving layer satisfies the above formula (II) [0.1 / 100 ≦ (A−B) / (B) ≦ 50/100]. % Of the aqueous solution satisfying the condition of pH of 4 to 8, and the vinyl alcohol polymer has a polymerization degree smaller than ½ times the weight average polymerization degree Pw, and the weight fraction of the polymer is 12% by weight or less. When the saponification degree is 95 mol% or more, various physical properties are further improved (Examples 16 to 22).
On the other hand, when a vinyl alcohol polymer having a Pw (weight average polymerization degree of vinyl alcohol polymer) x S (content of monomer unit having a silyl group) of 20 or less is used as a binder of the ink receiving layer, The surface strength of the ink receiving layer and the printing quality and water resistance of the recording paper are not sufficient (Comparative Example 14), and the vinyl alcohol polymer having Pw × S of 460 or more is completely in water. It was not possible to evaluate (Comparative Example 13).
In addition, among vinyl alcohol polymers, a vinyl alcohol polymer having a polymerization degree exceeding 3 times the weight average polymerization degree Pw and having a weight fraction exceeding 25% by weight is used as a binder for the ink receiving layer. In this case, it can be seen that the surface strength of the ink receiving layer and the water resistance of the recording paper are not sufficient (Comparative Examples 11 and 12).
When a vinyl alcohol polymer containing no silyl group-containing monomer is used as the binder of the ink receiving layer, it can be seen that the surface strength of the ink receiving layer, and the printing quality and water resistance of the recording paper are not sufficient ( Comparative Examples 9, 10, 15 and 16).

III. Thermal recording paper Thermal recording paper was produced by the following method, and its water resistance and plasticizer resistance were evaluated.

Example 31
(1) Preparation of aqueous dispersion of thermal dye, developer and pigment [composition of aqueous dispersion A of thermal dye]
Leuco dye (manufactured by Yamamoto Kasei, trade name: OBD-2) 20%
10% PVA (Kuraray: PVA203) aqueous solution 20%
60% water
[Composition of aqueous dispersion B of developer]
Developer (Nippon Soda: D-8) 20%
10% PVA (Kuraray: PVA203) aqueous solution 20%
60% water
[Composition of aqueous pigment dispersion C]
Stearic acid amide 10%
Baked kaolin 20%
30% PVA (made by Kuraray: PVA205) aqueous solution with a concentration of 5%
40% water

An aqueous dispersion A, an aqueous dispersion B and an aqueous dispersion C having the above composition were prepared separately, and pre-stirred for 15 minutes in a beaker.
Next, the aqueous dispersion A was transferred to a sand grinder (manufactured by Kansai Paint Co., Ltd .: batch type tabletop sand grinder), added with 300 mL of glass beads (soda quartz glass having a diameter of 0.5 mm), and at a high rotation speed (2170 rpm) under cooling. Under these conditions, the dispersoid was dispersed over 6 hours. As a result of measuring with a laser diffraction particle size measuring machine (manufactured by Shimadzu Corporation: SALD-1000), the dispersed particle size of the aqueous dispersion A of the obtained thermal dye was 0.46 μm. Moreover, as a result of measuring with the color difference meter (Nippon Denshoku Industries Co., Ltd. product: Z-1001DP), the whiteness of the aqueous dispersion A was -8.1. The whiteness indicates that 0 is completely white, and the greater the negative value is, the more colored it is.
Similarly, the aqueous dispersion B is transferred to a sand grinder, 300 mL of glass beads (soda quartz glass having a diameter of 0.5 mm) are added, and the dispersoid is dispersed over 6 hours under conditions of high rotation speed (2170 rpm) and cooling. I let you.
Further, the aqueous dispersion C was transferred to a homogenizer, and the dispersoid was dispersed for 2 minutes under the condition of a rotational speed of 10,000 rpm.

(2) Preparation of coating solution for thermosensitive coloring layer 2 parts of aqueous dispersion A, 4 parts of aqueous dispersion B, 2 parts of aqueous dispersion C and 2 parts of 10% aqueous solution of PVA5 were mixed and stirred. After that, a necessary amount of water was added to prepare a coating solution for a thermosensitive coloring layer having a solid concentration of 21%.
As a result of measurement using a BL type viscometer under the conditions of 25 ° C. and 30 rpm, the viscosity of the coating solution immediately after preparation was 280 mPa · s. The viscosity of the coating liquid after standing at 25 ° C. for 1 week was 1.10 times the viscosity immediately after the preparation and hardly changed, and the viscosity stability of the coating liquid was good.

(3) Preparation of coating liquid for overcoat layer Ethylene glycol-propylene glycol copolymer (Nippon Yushi Co., Ltd .: Pronon 104) 0.2 parts, silica (Shionogi Pharmaceutical Co., Ltd .: Carplex CS-5) 50 72.5 parts of water was added and sufficiently dispersed while adding 690 parts of a 12% aqueous solution of PVA1 slowly at room temperature, and then a zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd., Hydrin Z730; solid concentration) 30%) was added to prepare a silica-dispersed aqueous solution of PVA1.
While stirring the obtained silica-dispersed aqueous solution of PVA1, 30 parts of a 10% aqueous solution of titanium lactate was slowly added to this silica-dispersed aqueous solution at room temperature, and the required amount of water was added to the coating for an overcoat layer having a solid concentration of 15%. A working solution was prepared.
As a result of measurement using a BL type viscometer under the conditions of 25 ° C. and 30 rpm, the viscosity of the coating solution immediately after preparation was 360 mPa · s. The viscosity of the coating solution after being left for 1 week at 25 ° C. was 1.21 times the viscosity immediately after preparation and hardly changed, and the viscosity stability of the coating solution was good.

(4) Manufacture of thermal recording paper On the surface of the base paper (basis weight: 52 g / m ² high-quality paper), the coating solution for the thermal coloring layer prepared in (2) above is solidified using a wire bar coater. 6 g / m ^{2 was} applied in terms of conversion and dried at 50 ° C. for 5 minutes. The obtained coated paper is surface-treated with a super calender (linear pressure: 30 kg / cm), and the overcoat layer coating solution prepared in (3) above is applied to the coated paper surface using a wire bar coater. After coating 3 g / m ^{2 in} terms of solid content, it was dried at 50 ° C. for 10 minutes. Further, the coated paper was surface-treated with a super calendar (linear pressure: 30 kg / cm) to produce a heat-sensitive recording paper.
Immediately after the production of the thermal recording paper, printing was performed on the thermal recording paper using a thermal facsimile printer (Ricoh Co., Ltd .: Rifax 300), and its water resistance and plasticizer resistance were evaluated according to the following methods. The results are shown in Table 7.

[water resistant]
The printed thermal recording paper was immersed in distilled water at 30 ° C. for 24 hours, and the recording density and wet rub were evaluated by the following methods.
Recording density Before and after immersion in distilled water, the color density of the printed portion was measured using a Macbeth densitometer (manufactured by Macbeth, model: RD-514). The case where the water resistance of the thermal recording paper is excellent as the color density of the printed portion before immersion in distilled water decreases with a decrease in the color density of the printed portion after immersion in distilled water. A five-step evaluation was performed with 1 being the worst water resistance.
-Wet rub After the immersion in distilled water, the surface of the printed part was rubbed with a fingertip, and the elution state of the coating layer of the thermal recording paper was observed. As the water layer of the thermal recording paper is less eluted, the water resistance of the thermal recording paper is better. As a result, a five-step evaluation was performed, with 5 being the most excellent in water resistance and 1 being the worst in water resistance. .

[Plasticizer resistance]
A soft polyvinyl chloride film was superimposed on the printed thermal recording paper, and both were brought into contact with each other under a load of 30 g and 300 g / m ² for 24 hours. Before and after the contact, the color density of each printed portion was measured using a Macbeth densitometer (manufactured by Macbeth, model: RD-514). When the plasticizer resistance of the thermal recording paper is excellent as the color density of the printed part before contact with the two decreases less as the color density of the printed part decreases after contact. A five-step evaluation was performed, with 5 being the least plasticizer resistance and 1 being the worst case.

Examples 32-48
A thermosensitive recording paper was produced in the same manner as in Example 31 except that PVA having a silyl group shown in Table 7 was used in place of the PVA having a silyl group used in Example 31. The plasticizer resistance was evaluated. The results are also shown in Table 7.

Example 49
(1) Preparation of aqueous dispersion of thermal dye, developer and pigment [composition of aqueous dispersion A of thermal dye]
Leuco dye (manufactured by Yamamoto Kasei, trade name: OBD-2) 20%
10% PVA (Kuraray: PVA203) aqueous solution 20%
60% water
[Composition of aqueous dispersion B of developer]
Developer (Nippon Soda: D-8) 20%
10% PVA (Kuraray: PVA203) aqueous solution 20%
60% water
[Composition of aqueous pigment dispersion C]
Stearic acid amide 10%
Baked kaolin 20%
30% PVA (made by Kuraray: PVA205) aqueous solution with a concentration of 5%
40% water

An aqueous dispersion A, an aqueous dispersion B and an aqueous dispersion C having the above composition were prepared separately, and pre-stirred for 15 minutes in a beaker.
Next, the aqueous dispersion A was transferred to a sand grinder (manufactured by Kansai Paint Co., Ltd .: batch type tabletop sand grinder), added with 300 mL of glass beads (soda quartz glass having a diameter of 0.5 mm), and at a high rotation speed (2170 rpm) under cooling. Under these conditions, the dispersoid was dispersed over 6 hours. As a result of measuring with a laser diffraction particle size measuring machine (manufactured by Shimadzu Corporation: SALD-1000), the dispersed particle size of the aqueous dispersion A of the obtained thermal dye was 0.46 μm. Moreover, as a result of measuring with the color difference meter (Nippon Denshoku Industries Co., Ltd. product: Z-1001DP), the whiteness of the aqueous dispersion A was -8.1.
Similarly, the aqueous dispersion B is transferred to a sand grinder, 300 mL of glass beads (soda quartz glass having a diameter of 0.5 mm) are added, and the dispersoid is dispersed over 6 hours under conditions of high rotation speed (2170 rpm) and cooling. I let you.
Further, the aqueous dispersion C was transferred to a homogenizer, and the dispersoid was dispersed for 2 minutes under the condition of a rotational speed of 10,000 rpm.

(2) Preparation of coating solution for thermosensitive coloring layer 2 parts of aqueous dispersion A, 4 parts of aqueous dispersion B, 2 parts of aqueous dispersion C and 2 parts of 10% aqueous solution of PVA1 were mixed and stirred. Thereafter, 0.3 part of a 10% aqueous solution of titanium lactate was slowly added at room temperature, and a necessary amount of water was added to prepare a coating solution for a thermosensitive coloring layer having a solid content concentration of 21%.
As a result of measurement using a BL type viscometer under the conditions of 25 ° C. and 30 rpm, the viscosity of the coating liquid immediately after preparation was 310 mPa · s. The viscosity of the coating solution after being allowed to stand at 25 ° C. for 1 week was 1.19 times the viscosity immediately after preparation.

(3) Manufacture of thermal recording paper On the surface of the base paper (basis weight: 52 g / m ² high quality paper), the coating solution for the thermal coloring layer prepared in (2) above is solidified using a wire bar coater. 6 g / m ^{2 was} applied in terms of conversion and dried at 50 ° C. for 5 minutes. The obtained coated paper was surface-treated with a super calendar (linear pressure: 30 kg / cm) to produce a thermal recording paper. In the same manner as in Example 31, the water resistance and plasticizer resistance of the thermal recording paper were evaluated. The results are also shown in Table 7.

Examples 50-51
A thermosensitive recording paper was produced in the same manner as in Example 49 except that PVA having a silyl group shown in Table 7 was used instead of PVA having a silyl group used in Example 49. The plasticizer resistance was evaluated. The results are also shown in Table 7.

Comparative Examples 17-24
A heat-sensitive recording paper was produced in the same manner as in Example 31 except that the PVA shown in Table 8 was used instead of the PVA having a silyl group used in Example 31, and the water resistance and plasticizer resistance thereof were produced. Evaluated. The results are also shown in Table 8.

Comparative Examples 25-27
A heat-sensitive recording paper was produced in the same manner as in Example 49 except that PVA shown in Table 8 was used instead of PVA having a silyl group used in Example 49, and its water resistance and plasticizer resistance were Evaluated. The results are also shown in Table 8.

From the results shown in Table 7, when the vinyl alcohol polymer corresponding to the present invention is used in at least one of the thermosensitive coloring layer or the overcoat layer, the water resistance and plasticizer resistance of the thermosensitive recording paper are good. (Examples 31-51).
In particular, the vinyl alcohol polymer used for the overcoat layer satisfies the above formula (II) [0.1 / 100 ≦ (AB) / (B) ≦ 50/100], and a 4% aqueous solution thereof. The pH fraction of the polymer satisfies the conditions of 4 to 8, and in the vinyl alcohol polymer, the weight fraction of the polymer having a polymerization degree smaller than ½ times the weight average polymerization degree Pw is 12% by weight or less. And when the saponification degree is 95 mol% or more, various physical properties will become further excellent (Examples 31-37).

On the other hand, from the results shown in Table 8, when the vinyl alcohol polymer corresponding to the present invention is not used in either the heat-sensitive color developing layer or the overcoat layer, the heat-sensitive recording paper has good water resistance and plasticizer resistance. It can be seen that was not obtained (Comparative Examples 17 to 27).
Among them, a vinyl alcohol polymer having Pw (weight average polymerization degree of vinyl alcohol polymer) × S (content of monomer unit having a silyl group) of 20 or less is used for the thermosensitive coloring layer and the overcoat layer. In this case, the water resistance of the thermal recording paper is not sufficient (Comparative Example 22), and when a vinyl alcohol polymer having Pw × S of 460 or more is used for the overcoat layer, the vinyl alcohol polymer is water. Therefore, the thermal recording paper could not be evaluated (Comparative Example 21).
Further, among vinyl alcohol polymers, when a vinyl alcohol polymer having a polymerization degree exceeding 3 times the weight average polymerization degree Pw and having a weight fraction exceeding 25% by weight is used for the overcoat layer, It can be seen that the heat-sensitive recording paper has insufficient water resistance (Comparative Examples 19 and 20). Even when a vinyl alcohol polymer having no silyl group was used for the thermosensitive coloring layer and the overcoat layer, the water resistance of the thermosensitive recording paper was not sufficient (Comparative Examples 17, 18, 23 and 24).
Further, when the vinyl alcohol polymer corresponding to the present invention was not used for the thermosensitive coloring layer and there was no overcoat layer, the water resistance and the plasticizer resistance of the thermosensitive recording paper were not sufficient (Comparative Example 25). ~ 27).

The silyl group-containing vinyl alcohol polymer of the present invention can be dissolved in water to prepare an aqueous solution without adding an alkali or acid such as sodium hydroxide, and the viscosity of the prepared aqueous solution can be stabilized. Performance, water resistance of a film obtained from the aqueous solution, water resistance of a film containing an inorganic substance, and binder strength with an inorganic substance at the same time. Excellent performance as a coating agent used in combination with an inorganic substance in various applications. Have In addition, by applying a coating agent containing the silyl group-containing vinyl alcohol polymer of the present invention to a substrate, an ink jet recording material and a heat sensitive recording material excellent in various performances such as water resistance can be obtained.

Claims (9)

The following general formula (1)

(R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have an oxygen-containing substituent, and m is 0 to 2 Is an integer.)
A vinyl alcohol polymer obtained by saponifying a vinyl ester polymer containing a monomer unit having a silyl group represented by formula (1), which satisfies the following formula (I) and is a vinyl alcohol polymer: Among them, a vinyl alcohol polymer characterized in that the weight fraction of the polymer having a degree of polymerization exceeding 3 times the weight average degree of polymerization is 25% by weight or less.
20 <Pw × S <460 (I)
Pw: Weight average polymerization degree of vinyl alcohol polymer S: Content of monomer unit having silyl group represented by general formula (1) (mol%) 2. The vinyl alcohol according to claim 1, wherein in the vinyl alcohol polymer, the weight fraction of the polymer having a degree of polymerization smaller than ½ times the weight average degree of polymerization is 12% by weight or less. Polymer. The vinyl alcohol polymer according to claim 1 or 2, which satisfies the following formula (II) and has a 4% aqueous solution having a pH of 4 to 8.
0.1 / 100 ≦ (A−B) / (B) ≦ 50/100 (II)
A: Content of silicon atom in vinyl alcohol polymer (unit: ppm)
B: Content of silicon atom in vinyl alcohol polymer washed with methanol containing sodium hydroxide and then washed with Soxhlet extraction with methanol (unit: ppm)
Here, A and B are measured by ICP emission spectrometry after ashing the measurement sample. Vinyl ester monomer and the following general formula (1)

(Wherein R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have a substituent containing oxygen, and m is It is an integer from 0 to 2.)
2. The method for producing a vinyl alcohol polymer according to claim 1, wherein the vinyl ester polymer is saponified by copolymerizing with a monomer having a silyl group represented by formula (1). A monomer having a silyl group is represented by the following general formula (2)

(Wherein R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have a substituent containing oxygen, and m is (It is an integer from 0 to 2, and n is an integer from 0 to 4.)
Or the following general formula (3)

(In the formula, R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² is an alkoxyl group or an acyloxyl group, and these groups may have a substituent containing oxygen, and 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, R ⁵ is an alkylene group having 1 to ⁵ carbon atoms, or 2 containing an oxygen atom or a nitrogen atom Is a valent hydrocarbon group, and m is an integer of 0 to 2.)
The method for producing a vinyl alcohol polymer according to claim 4, wherein the monomer is represented by the formula: A coating agent comprising the vinyl alcohol polymer according to any one of claims 1 to 3. A coated product obtained by coating the base material with the coating agent according to claim 6. An ink jet recording material obtained by coating the base material with the coating agent according to claim 6. A heat-sensitive recording material obtained by coating the base material with the coating agent according to claim 6.