JP2014095059A - Binder for inorganic matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for an inorganic matter capable of obtaining a film having high water resistance, excellent in the water resistance and strength of the molding body to be obtained, and further sufficiently satisfying treatability and viscosity stability.SOLUTION: Provided is a binder for an inorganic matter comprising a vinyl alcohol-based polymer including a monomer unit having a group represented by formula (1) and satisfying formula (I). The vinyl alcohol-based polymer preferably satisfies inequalities (II) and (III) as well: 370≤P×S≤6,000 (I), 200≤P≤4,000 (II) and 0.1≤S≤10 (III). P: a viscosity average polymerization degree; and S: the content (mol%) of the monomer unit.

Description

  The present invention relates to an inorganic binder containing a vinyl alcohol polymer.

  A vinyl alcohol polymer represented by polyvinyl alcohol (hereinafter sometimes abbreviated as “PVA”) is known as a water-soluble synthetic polymer, and is a raw material for vinylon which is a synthetic fiber, a paper processing agent. It is widely used for fiber processing agents, adhesives, stabilizers for emulsion polymerization and suspension polymerization, inorganic binders, films and the like. In particular, PVA is superior in strength properties and film-forming properties compared to other water-soluble synthetic polymers. By utilizing these properties, binders for molding inorganic materials such as ceramics, concrete, mortar, slate, etc., just after spinning In order to protect the glass fiber, it is used as a binder for inorganic substances such as a binder for glass fiber that forms a film on the surface of the glass fiber.

  In order to further enhance the properties of such PVA, PVA with various modifications has been developed. As one of the modified PVA, silyl group-containing PVA can be mentioned. This silyl group-containing PVA has high water resistance and high binder strength against inorganic substances. However, the silyl group-containing PVA is (a) difficult to dissolve unless an alkali or acid such as sodium hydroxide is added when preparing an aqueous solution, and (b) the viscosity stability of the prepared aqueous solution is low. When (c) a film containing an inorganic substance is formed, it is difficult to simultaneously satisfy the water resistance of the resulting film and the binder strength against the inorganic substance. Therefore, when the silyl group-containing PVA is used as a binder for molding an inorganic material, it is difficult to satisfy the water resistance and strength of the molded body at the same time. When used as a treating agent, there are inconveniences such as difficulty in simultaneously satisfying the adhesive force between the silyl group-containing PVA and the glass fiber and the water resistance of the formed film.

  Therefore, water solubility and the like are improved by setting the product (P × S) of the viscosity average degree of polymerization (P) and the content of the monomer unit having a silyl group (S: mol%) within a certain range. Proposed silyl group-containing PVA (see JP-A-2004-43644) and coating agents containing such silyl group-containing PVA (see JP-A-2005-194437) have been proposed. However, in these silyl group-containing PVA, the upper limit of the product (P × S) is 370, and the content of the monomer unit having a silyl group is increased to enhance the characteristics as the silyl group-containing PVA. And the trade-off relationship between improving water solubility and the like has not been resolved. That is, as described in paragraph 0009 of JP 2004-43644 A, when the product (P × S) is 370 or more, an alkali or an acid is added when preparing an aqueous solution of silyl group-containing PVA. Otherwise, there is a disadvantage in handling that it may not be dissolved. That is, it cannot be said that the silyl group-containing PVA sufficiently solves the above-mentioned disadvantages.

JP 2004-43644 A JP 2005-194437 A

  The present invention has been made based on the circumstances as described above, can obtain a highly water-resistant film, is excellent in water resistance and strength of the resulting molded article, and sufficiently satisfies handling properties and viscosity stability. An object of the present invention is to provide an inorganic binder.

The invention made to solve the above problems is
It is a binder for inorganic substances containing a vinyl alcohol polymer that includes a monomer unit having a group represented by the following formula (1) and satisfies the following formula (I).

（式（１）中、Ｒ^１は、水素原子又は炭素数１〜５のアルキル基である。Ｒ^２は、アルコキシル基、アシロキシル基又はＯＭで表される基である。Ｍは、水素原子、アルカリ金属又はアンモニウム基である。Ｒ^３及びＲ^４は、それぞれ独立して、水素原子又はアルキル基である。Ｒ^１〜Ｒ^４で表されるアルキル基、アルコキシル基及びアシロキシル基が有する水素原子は、酸素原子又は窒素原子を含有する置換基で置換されていてもよい。ｍは、０〜２の整数である。ｎは、３以上の整数である。Ｒ^１〜Ｒ^４がそれぞれ複数存在する場合、複数存在する各Ｒ^１〜Ｒ^４は、独立して上記定義を満たす。）
３７０≦Ｐ×Ｓ≦６，０００ ・・・（Ｉ）
Ｐ：粘度平均重合度
Ｓ：上記単量体単位の含有率（モル％）

(In Formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ² is an alkoxyl group, an acyloxyl group, or a group represented by OM. M is a hydrogen atom, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group, each of which represents an alkyl group, an alkoxyl group or an acyloxyl group represented by R ^{1 to} R ^4. May be substituted with a substituent containing an oxygen atom or a nitrogen atom, m is an integer of 0 to 2. n is an integer of 3 or more, and there are a plurality of R ^{1 to} R ⁴ , respectively. In the case, a plurality of each R ^{1 to} R ⁴ independently satisfy the above definition.)
370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  The PVA contained in the inorganic binder includes a monomer unit having a group represented by the above formula (1), and a structure in which a silyl group is linked to a main chain via an alkylene group having 3 or more carbon atoms. have. For this reason, even if the said binder for inorganic substances raises the modified | denatured amount of the silyl group of PVA contained, since the water solubility in a neutral region is high, handling property is also good and the fall of viscosity stability is suppressed. Further, according to the inorganic binder, since the product (P × S) of the viscosity average polymerization degree (P) of the contained PVA and the content (S) of the monomer unit is in the above range, the silyl group A film having high water resistance can be obtained by increasing the amount of modification, and a molded article having excellent water resistance and strength can be obtained.

It is preferable that the PVA further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  Thus, by setting the viscosity average degree of polymerization (P) of the PVA and the content (S) of the monomer unit in the above ranges, water solubility and viscosity stability are increased, and the water resistance of the resulting film is improved. The water resistance and strength of the resulting molded product can be further increased.

  In the above formula (1), n is preferably an integer of 6 to 20. By making the value of n into the above range, various performances of the inorganic binder can be further enhanced.

（式（２）中、Ｒ^１〜Ｒ^４、ｍ及びｎの定義は、式（１）と同様である。Ｘは、直接結合、２価の炭化水素基又は酸素原子若しくは窒素原子を含む２価の有機基である。Ｒ^５は、水素原子又はメチル基である。） The monomer unit is preferably represented by the following formula (2).

(In formula (2), the definitions of R ^{1 to} R ⁴ , m and n are the same as those in formula (1). X represents a direct bond, a divalent hydrocarbon group, an oxygen atom or a nitrogen atom 2. R ⁵ is a hydrogen atom or a methyl group.)

  When the monomer unit has a structure represented by the formula (2), various performances of the inorganic binder can be further improved.

X in the above formula (2) is preferably represented by the following formula (3).
-CO-NR ^6- * (3)
(In the formula (3), R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. * Indicates a bonding position with the group represented by the above formula (1).)

  Thus, when the monomer unit has an amide structure at a position away from the silyl group, water solubility and viscosity stability can be further improved while maintaining the performance derived from the silyl group.

R ⁶ in the above formula (3) is a hydrogen atom, and n in the above formula (2) is preferably an integer of 3 to 12. By setting the monomer unit to such a structure, the water solubility and viscosity stability of the PVA can be increased, and various properties of the film and molded body obtained by the inorganic binder can be enhanced. PVA can be easily manufactured.

  Since the inorganic binder is excellent in the water resistance of the resulting film and the water resistance and strength of the obtained molded article, it is suitably used as a binder for inorganic fibers.

  Moreover, since the said binder for inorganic substances is excellent in the adhesive force between glass fibers in addition to the above-mentioned effect, it is used suitably as a binder for glass fibers.

  As described above, the inorganic binder of the present invention has sufficient handling properties and viscosity stability, and is excellent in the water resistance of the resulting film and the water resistance and strength of the resulting molded article. Therefore, the binder for inorganic substances of the present invention is suitably used as a binder for inorganic fibers and a binder for glass fibers.

  Hereinafter, embodiments of the inorganic binder according to the present invention will be described in detail.

<Inorganic binder>
The inorganic binder of the present invention contains PVA described in detail below.

<PVA>
The PVA includes a monomer unit having a group represented by the formula (1). That is, the PVA is a copolymer containing a monomer unit having a group represented by the formula (1) and a vinyl alcohol unit (—CH ₂ —CHOH—), and further another monomer unit. You may have.

In the above formula (1), ^{R 1} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group.

R ² is a group represented by an alkoxyl group, an acyloxyl group, or OM. M is a hydrogen atom, an alkali metal, or an ammonium group ( ⁺ NH ₄ ). Examples of the alkoxyl group include a methoxy group and an ethoxy group. Examples of the acyloxyl group include an acetoxy group and a propionyloxy group. Examples of the alkali metal include sodium and potassium. Among these groups represented by R ² , an alkoxyl group or a group represented by OM is preferable, an alkoxyl group having 1 to 5 carbon atoms, and a group represented by OM in which M is a hydrogen atom or an alkali metal. More preferably, a methoxy group, an ethoxy group, and a group represented by OM in which M is sodium or potassium are more preferable.

R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include the above-described alkyl groups having 1 to 5 carbon atoms. R ³ and R ⁴ are preferably a hydrogen atom or a methyl group.

The hydrogen atom which the alkyl group, alkoxyl group, and acyloxyl group represented by R ^{1 to} R ⁴ have may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include an alkoxyl group and an acyloxyl group. In addition, examples of the substituent containing a nitrogen atom include an amino group and a cyano group.

In ^the case where R 1 to R ⁴ is present in plural, each ^R 1 to R ⁴ that there are two or more, independently meets the above definition.

m is an integer of 0 to 2, and 0 is preferable. When m is 0, that is, the monomer unit has three R ² groups, the effect of modification can be further enhanced.

n is an integer of 3 or more. The upper limit of n is not particularly limited, but 20 is preferable, 15 is more preferable, and 12 is more preferable. As a lower limit of n, 4 is preferable, 6 is more preferable, and 8 is more preferable. The PVA has a structure in which n in the formula (1) is 3 or more, that is, the silyl group is connected to the main chain via an alkylene group having 3 or more carbon atoms, so that the amount of modification of the silyl group can be reduced. Even if it raises, the fall of water solubility and viscosity stability is suppressed. The reason why such an effect is not fully elucidated has been elucidated, but for example, an alkylene group having 3 or more carbon atoms exhibiting hydrophobicity reduces the hydrolysis rate of Si—R ² in an aqueous solution, thereby causing a reaction. It is presumed to be for inhibiting.

  The specific structure of the monomer unit is not particularly limited as long as it has a group represented by the above formula (1), but is preferably represented by the above formula (2).

In formula (2), the definitions of R ^{1 to} R ⁴ , m and n are the same as in formula (1). The same applies to these preferred groups or numerical ranges.

  X is a direct bond, a divalent hydrocarbon group, or a divalent organic group containing an oxygen atom or a nitrogen atom. When the monomer unit has a structure represented by the above formula (2), water solubility and viscosity stability, water resistance of the obtained film, and water resistance and strength of the obtained molded body can be further increased. .

  Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and the like. Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include a methylene group, an ethylene group, and a propylene group. Examples of the divalent aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenylene group. Examples of the divalent organic group containing an oxygen atom include ether groups, ester groups, carbonyl groups, amide groups, and groups in which these groups are connected to a divalent hydrocarbon group. Examples of the divalent organic group containing a nitrogen atom include an imino group, an amide group, and a group in which these groups are connected to a divalent hydrocarbon group.

Among the groups represented by X, a divalent organic group containing an oxygen atom or a nitrogen atom is preferable, a group containing an amide group is more preferable, and —CO—NR ⁶ — * (R ⁶ is a hydrogen atom or a carbon atom) It is an alkyl group having 1 to 5 atoms. * Is more preferably a group represented by the bonding site with the group represented by the above formula (1). In this way, the monomer unit has a polar structure, preferably an amide structure, at a position away from the silyl group, so that the performance derived from the silyl group is maintained and the water solubility and viscosity stability are further improved. Can do. As the above R ^6, or more increase the above-mentioned function, from the viewpoint of the production of the PVA can be easily performed, a hydrogen atom is preferable.

R ⁵ is a hydrogen atom or a methyl group.

  As said monomer unit, what is represented by following formula (4) is still more preferable.

In the formula (4), the definitions of R ¹ , R ² , R ⁵ , X and m are the same as those in the above formula (2). The same applies to these preferred groups or numerical ranges.

In the above formula (4), R ³ ′ and R ⁴ ′ are each independently a hydrogen atom or an alkyl group. As this alkyl group, the C1-C5 alkyl group mentioned above is mentioned. R ³ ′ and R ⁴ ′ are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. The hydrogen atom contained in the alkyl group represented by R ³ ′ and R ⁴ ′ may be substituted with a substituent containing an oxygen atom or a nitrogen atom. Examples of the substituent containing an oxygen atom include an alkoxyl group and an acyloxyl group. In addition, examples of the substituent containing a nitrogen atom include an amino group and a cyano group. When there are a plurality of R ³ ′ and R ⁴ ′, a plurality of R ³ ′ and R ⁴ ′ satisfy the above definition independently.

  In the above formula (4), n ′ is an integer of 1 or more. The upper limit of n 'is not particularly limited, but 18 is preferable, 13 is more preferable, and 10 is more preferable. As a lower limit of n ′, 2 is preferable, 4 is more preferable, and 6 is more preferable.

When the said monomer unit is represented by the said Formula (4), the various functions of the said binder for inorganic substances can be expressed more effectively. The reason for this is not clear, but it is presumed that the above-described function of reducing the hydrolysis rate of Si—R ² and inhibiting the reaction in the aqueous solution is more effectively exhibited.

The PVA satisfies the following formula (I).
370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

The viscosity average degree of polymerization (P) is measured according to JIS-K6726. That is, when the saponification degree of the PVA is less than 99.5 mol%, the saponification degree is re-saponified to 99.5 mol% or more, and after purification, the intrinsic viscosity [η] measured in water at 30 ° C. (unit: (Deciliter / g) can be obtained by the following equation.
P = ([η] × 1000 / 8.29) ^{(1 / 0.62)}

The content of the monomer unit (S: mol%) can be obtained from proton NMR of the vinyl ester polymer before saponification. Here, when the proton NMR of the vinyl ester polymer before saponification is measured, the vinyl ester polymer is purified by reprecipitation with hexane-acetone, and the monomer having an unreacted silyl group is contained in the polymer. The body is sufficiently removed and then dried at 90 ° C. under reduced pressure for 2 days, and then dissolved in CDCl ₃ solvent for analysis.

The product (P × S) of the viscosity average degree of polymerization (P) and the content (S) of the monomer units corresponds to the number (average value) of the monomer units per 100 molecules. When this product (P × S) is less than the above lower limit, the water resistance of the film obtained from the inorganic binder and the properties derived from the silyl group such as the water resistance and strength of the obtained molded article are sufficiently exhibited. I can't. On the other hand, when this product (P × S) exceeds the above upper limit, water solubility and viscosity stability decrease. The product (P × S) preferably satisfies the following formula (I ′), and more preferably satisfies the following formula (I ″).
400 ≦ P × S ≦ 3,000 (I ′)
500 ≦ P × S ≦ 2,000 (I ″)

The PVA preferably further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)

  Thus, by setting the viscosity average degree of polymerization (P) and the content (S) of the monomer unit in the above ranges, water solubility and viscosity stability, water resistance of the resulting film, water resistance of the resulting molded body Property and strength can be increased.

Furthermore, in the viscosity average polymerization degree (P), it is more preferable to satisfy the following formula (II ′), and it is more preferable to satisfy the following formula (II ″).
500 ≦ P ≦ 3,000 (II ′)
1,000 ≦ P ≦ 2,400 (II ″)

  When the viscosity average degree of polymerization (P) is less than the above lower limit, the water resistance of the resulting film, the water resistance and strength, etc. of the resulting molded article may be reduced. Conversely, when the viscosity average degree of polymerization (P) exceeds the above upper limit, water solubility, viscosity stability and the like may be lowered.

Moreover, in the content rate of the said monomer unit, it is more preferable to satisfy | fill following formula (III '), and it is still more preferable to satisfy | fill following formula (III'').
0.25 ≦ S ≦ 6 (III ′)
0.5 ≦ S ≦ 5 (III ″)

  When the content (S) of the monomer unit is less than the lower limit, the water resistance of the resulting film, the water resistance and strength of the resulting molded article, and the like may be reduced. On the other hand, when the content (S) of the monomer unit exceeds the upper limit, water solubility and viscosity stability may be deteriorated.

  Although there is no restriction | limiting in particular as the saponification degree of the said PVA, 80 mol% or more is preferable, 90 mol% or more is more preferable, 95 mol% or more is more preferable, 97 mol% or more is especially preferable. When the saponification degree of the PVA is less than the above lower limit, the water resistance of the obtained film, the water resistance and strength of the obtained molded product, and the like may be lowered. The upper limit of the saponification degree of the PVA is not particularly limited, but is 99.9 mol%, for example, in consideration of productivity. Here, the degree of saponification of PVA refers to a value measured according to the method described in JIS-K6726.

<Method for producing PVA>
Although it does not specifically limit as a manufacturing method of the said PVA, For example, a copolymer obtained by copolymerizing a vinyl ester monomer and the monomer which has group represented by the said Formula (1) ( It can be obtained by saponifying a vinyl ester polymer).

  Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate and the like. Can be mentioned. Among these, vinyl acetate is preferable.

  In addition, for the purpose of adjusting the viscosity average polymerization degree (P) of the obtained PVA at the time of copolymerization of the monomer having a group represented by the above formula (1) and a vinyl ester monomer, Polymerization may be carried out in the presence of a chain transfer agent as long as the gist of the present invention is not impaired. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde; ketones such as acetone and methyl ethyl ketone; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-hydroxyethanethiol, n-dodecanethiol, Mercaptans such as mercaptoacetic acid and 3-mercaptopropionic acid; and halogenated hydrocarbons such as tetrachloromethane, bromotrichloromethane, trichloroethylene and perchloroethylene.

  As a monomer which has group represented by the said Formula (1), the compound represented, for example by following formula (5) is mentioned. By using a compound represented by the following formula (5), finally, a PVA containing a monomer unit having a group represented by the above formula (2) can be easily obtained.

In formula (5), the definitions of R ^{1 to} R ⁵ , X, m, and n are the same as in formula (2). The same applies to these preferred groups or numerical ranges.

  Examples of the compound represented by the above formula (5) include 3- (meth) acrylamidopropyltrimethoxysilane, 4- (meth) acrylamidobutyltrimethoxysilane, 6- (meth) acrylamidehexyltrimethoxysilane, 8- ( (Meth) acrylamide octyltrimethoxysilane, 12- (meth) acrylamide dodecyltrimethoxysilane, 18- (meth) acrylamide octadecyltrimethoxysilane, 3- (meth) acrylamidepropyltriethoxysilane, 3- (meth) acrylamidepropyltributoxy Silane, 3- (meth) acrylamidopropylmethyldimethoxysilane, 3- (meth) acrylamidopropyldimethylmethoxysilane, 3- (meth) acrylamide-3-methylbutyltrimethoxysilane, 4- (Meth) acrylamide-4-methylbutyltrimethoxysilane, 4- (meth) acrylamide-3-methylbutyltrimethoxysilane, 5- (meth) acrylamide-5-methylhexyltrimethoxysilane, 4-pentenyltrimethoxysilane, 5 -Hexenyltrimethoxysilane and the like.

  Examples of the method for copolymerizing the vinyl ester monomer and the monomer having the group represented by the formula (1) include a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. A well-known method is mentioned. In particular, when the polymerization temperature is lower than 30 ° C., an emulsion polymerization method is preferable, and when the polymerization temperature is 30 ° C. or higher, a bulk polymerization method performed without solvent or a solution polymerization method performed using a solvent such as alcohol is used. Usually adopted.

  In the case of the emulsion polymerization method, examples of the solvent include water, and lower alcohols such as methanol and ethanol may be used in combination. Moreover, a well-known emulsifier can be used as an emulsifier. As an initiator for copolymerization, a redox initiator using iron ions, an oxidizing agent and a reducing agent in combination is preferably used for controlling the polymerization. In the case of the bulk polymerization method or the solution polymerization method, the reaction can be carried out by either a batch method or a continuous method in carrying out the copolymerization reaction. 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 methanol, ethanol, and propanol. Examples of the initiator used for the copolymerization reaction in this case include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 1,1′-azobis ( Azo initiators such as cyclohexane-1-carbonitrile) and 2,2′-azobis (N-butyl-2-methylpropionamide); peroxide initiators such as benzoyl peroxide and n-propyl peroxycarbonate And known initiators such as Although there is no restriction | limiting in particular about the polymerization temperature at the time of performing a copolymerization reaction, The range of 5 to 50 degreeC is suitable.

  In the case of this copolymerization reaction, a copolymerizable monomer can be copolymerized as necessary as long as the gist of the present invention is not impaired. Examples of such a monomer 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 acid 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; Methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide and N-ethylmethacrylamide; Vinyl ethers such as til 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; allyl ethers such as propyl allyl ether, butyl allyl ether, hexyl allyl ether; monomers having an oxyalkylene group; isopropenyl acetate; 3-buten-1-ol, 4-penten-1-ol, 5 -Hydroxyl-containing α-olefins such as hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol; vinyl sulfone , Monomers having a sulfonic acid group such as allylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine , Having a cationic group such as vinyloxymethyldiethylamine, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine And monomers. The amount of these monomers used varies depending on the purpose and application of use, but is usually 20 mol% or less based on all monomers used for copolymerization, % Or less is preferable.

  The vinyl ester polymer obtained by the copolymerization is then saponified in a solvent according to a known method and led to PVA.

  As the catalyst for the saponification reaction, an alkaline substance is usually used, and examples thereof include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and alkali metal alkoxides such as sodium methoxide. 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. More preferably, it is in the range of 0.05. Further, this 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 in the middle of 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. Of these solvents, methanol is preferred. Further, in the use of methanol, the water content in methanol is preferably adjusted to 0.001 to 1% by mass, more preferably 0.003 to 0.9% by mass, and particularly preferably 0.005 to 0.8% by mass. It is good to be.

  The saponification reaction is preferably performed at a temperature of 5 ° C to 80 ° C, more preferably 20 ° C 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 usable neutralizing agents include organic acids such as acetic acid and lactic acid, and ester compounds such as methyl acetate. .

  The PVA obtained by the saponification reaction can be washed as necessary. Examples of the cleaning liquid used in this cleaning include lower alcohols such as methanol, lower fatty acid esters such as methyl acetate, and mixtures thereof. A small amount of water, alkali, acid, or the like may be added to these cleaning liquids.

  Although it does not specifically limit as a content rate of the said PVA in the said binder for inorganic substances, 4 mass% or more and 20 mass% or less are preferable. According to the inorganic binder, since the concentration can be made relatively high as described above, the water resistance of the resulting film, the water resistance, strength, and the like of the obtained molded body can be effectively increased.

<Other ingredients>
The inorganic binder is usually an aqueous solution of the PVA. However, it may be a solution using another solvent. Other inorganic binders include:
Other solvents such as alcohols such as ethanol, ethers such as diethyl ether;
Alkali such as sodium hydroxide and ammonia;
Acids such as hydrochloric acid and acetic acid;
Albumin, gelatin, casein, starch, cationized starch, gum arabic, polyamide resin, melamine resin, poly (meth) acrylamide, polyvinylpyrrolidone, poly (meth) acrylate sodium, anion-modified PVA, sodium alginate, water-soluble polyester, and Water-soluble resins such as cellulose derivatives such as methylcellulose, hydroxyethylcellulose, and carboxymethylcellulose (CMC);
Water-dispersible resins such as SBR, NBR, vinyl acetate resins such as ethylene-vinyl acetate copolymer, (meth) acrylic acid ester resins, vinyl chloride resins;
Inorganic particles such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, precipitated silica, gelled silica, colloidal silica, aluminum oxide, aluminum hydroxide;
Aldehyde compounds such as glioxal and glutaraldehyde, titanium compounds such as titanium lactate, epoxy compounds such as polyamidoamine epichlorohydrin, and cross-linking agents such as polyoxazoline;
Water-soluble inorganic substances such as water glass, sodium aluminate, ammonium zirconium carbonate;
coupling agents such as r-aminopropyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane;
Smoothing agents such as fatty acid amide type surfactants, cationic surfactants, anionic surfactants or nonionic surfactants;
Diluents such as water, methanol, acetone;
A water-soluble polymer such as unmodified PVA;
Etc. may be contained.

  The pH of the inorganic binder is not particularly limited, but is preferably 4 or more and 8 or less. Since the PVA used for the inorganic binder is excellent in solubility in water, a uniform aqueous solution can be obtained without adding an alkali or acid such as sodium hydroxide to water, and the handleability is excellent. . Moreover, according to the said binder for inorganic substances, sufficient viscosity stability can be exhibited also in a neutral area | region.

<Applicable inorganic types>
The binder for inorganic substances of the present invention contains the above-mentioned PVA. Examples of inorganic materials include clay, kaolin, silica, aluminum hydroxide, zinc oxide, bentonite, soil, sand and other elements such as silicon, aluminum, magnesium, calcium, concrete, mortar, cement, slate, gypsum, Examples thereof include crystallized glass, glass block, glass, glass fiber, brick, and zeolite. As an embodiment of the inorganic binder, an inorganic fiber binder and a glass fiber binder are preferable. Hereinafter, these will be specifically described sequentially.

<Binder for inorganic fibers>
The binder for inorganic substances of the present invention is suitably used as a binder for inorganic fibers, and is added and used when molding inorganic fibers. In forming the inorganic fiber, it is usually added and used as an aqueous solution. However, in some cases, the inorganic fiber can be added and used in the form of powder. The binder for inorganic fibers has a sufficient effect even when used alone with the silyl group-containing PVA, but it is preferable to further blend the above-mentioned water-soluble inorganic substance or the above-mentioned inorganic particles. The fiber bonded with the inorganic fiber binder is not particularly limited as long as it is an inorganic fiber, but at least one fiber selected from the group consisting of asbestos and rock wool is preferable. When used as a binder for inorganic fibers, the addition amount of the inorganic binder is not particularly limited, but is usually 0.5 to 30 parts by mass and 2 to 20 parts by mass with respect to 100 parts by mass of the inorganic fiber. Part by mass is preferred.

<Binder for glass fiber>
The binder for inorganic substances of the present invention is suitably used as a binder for glass fibers, and is used for forming a film on the surface of glass fibers. As the main component of the glass fiber binder, the above-mentioned PVA aqueous solution is used, but it may further contain the above-mentioned coupling agent, smoothing agent, diluent and the like. Moreover, you may contain water-soluble polymers, such as the above-mentioned starch and unmodified PVA, nonionic, anionic or cationic synthetic resin emulsions. As the coupling agent, a silane coupling agent composed of a silane compound such as γ-aminopropyltriethoxysilane and vinyltri (β-methoxy-ethoxy) silane is preferable. When used as a glass fiber binder, the composition in the inorganic binder is not particularly limited, but silyl group-containing PVA 0.2 mass% to 20 mass%, coupling agent 0 mass% to 50 mass%, smoothing agent 0 mass% % To 1% by mass, and the remainder is preferably used as a diluent, and is preferably applied so that the total solid content attached to the glass fiber is 0.1% to 5% by mass. The application method is not particularly limited, but may be a method generally called sizing, that is, a method of applying and drying glass fibers at the applicator during spinning, or a method of impregnating glass fiber products. The glass fiber binder is particularly preferably used as a glass fiber bundling agent.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the following examples and comparative examples, unless otherwise specified, parts and% represent parts by mass and mass%, respectively.

In addition, the monomer (monomer A) which has the silyl group used by the Example and the comparative example is as follows.
MAmPTMS: 3-methacrylamideamidopropyltrimethoxysilane MAmPTES: 3-methacrylamideamidopropyltriethoxysilane MAmBTMS: 4-methacrylamidobutyltrimethoxysilane MAmOTMS: 8-methacrylamidooctyltrimethoxysilane MAmDDTMS: 12-methacrylamidododecyltrimethoxysilane MAmODTMS: 18-methacrylamidooctadecyltrimethoxysilane AMBTMS: 3-acrylamido-3-methylbutyltrimethoxysilane 4-PTMS: 4-pentenyltrimethoxysilane VMS: vinyltrimethoxysilane MAMTMTS: methacrylamidomethyltrimethoxysilane AMPTMS: 2 -Acrylamide-2-methylpropyltrimethoxysilane

[Synthesis of silyl group-containing PVA]
PVA is produced by the following method, the degree of saponification, the content of monomer units having a group represented by the above formula (1) (S) (in some examples, monomer units having a silyl group) Content) and viscosity average degree of polymerization (P). Moreover, according to the following evaluation methods, the performance of the binder for inorganic substances was evaluated.

[Analysis method of PVA]
Analysis of PVA was performed according to the method described in JIS-K6726 unless otherwise specified.

[Synthesis Example 1] Production of PVA1 Into a 6 L separable flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a comonomer dropping port and an initiator addition port, 1,500 g of vinyl acetate, 500 g of methanol, the above formula (1 ) MAmPTMS 1.87 g as a monomer (monomer A) having a group represented by) was charged, and the inside of the system was purged with nitrogen for 30 minutes while carrying out nitrogen bubbling. Further, a comonomer solution having a concentration of 8% was prepared by dissolving MAmPTMS in methanol as a delay solution, and nitrogen substitution was performed by bubbling nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.8 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. The delay solution was added dropwise to polymerize the monomer composition (ratio of vinyl acetate and monomer A (MAmPTMS)) in the polymerization solution at a constant rate for 2.7 hours at 60 ° C. and then cooled to stop the polymerization. . The total amount of comonomer solution (sequentially added solution) added until the polymerization was stopped was 99 g. Further, the solid content concentration when the polymerization was stopped was 29.0%. Subsequently, an unreacted vinyl acetate monomer is removed while sometimes adding methanol under reduced pressure at 30 ° C., and a methanol solution containing 40% of polyvinyl acetate (PVAc) having a group represented by the above formula (1) Got. Furthermore, a methanol solution containing 10% by mass of methanol and sodium hydroxide was added so that the molar ratio of sodium hydroxide to the vinyl acetate unit in PVAc was 0.04 and the solid content concentration of PVAc was 30% by mass. In this order, with stirring, the saponification reaction was started at 40 ° C. A gel was formed in about 5 minutes after the addition of the alkaline solution. This gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. Methanol was added thereto, and the mixture was allowed to wash at room temperature for 3 hours. After repeating the above washing operation three times, the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain PVA1 having a group represented by the above formula (1). PVA1 had a viscosity average polymerization degree (P) of 1,700 and a saponification degree of 98.6 mol%.

The content of the monomer unit having the group represented by the above formula (1) of the obtained PVA1 (content of the monomer unit having a silyl group) is the proton NMR of PVAc which is a precursor of this PVA. I asked for it. Specifically, after reprecipitation purification of the obtained PVAc was sufficiently performed three times or more with n-hexane / acetone, drying was performed under reduced pressure at 50 ° C. for 2 days to prepare a PVAc for analysis. This PVAc was dissolved in CDCl ₃ and measured at room temperature using 500 MHz proton NMR (JEOL GX-500). From the peak α (4.7 to 5.2 ppm) derived from the main chain methine of the vinyl acetate unit and the peak β (3.4 to 3.8 ppm) derived from the methyl of the methoxy group of the monomer A unit, the following formula is obtained. The content (S) of the monomer unit having a group represented by the formula (1) was calculated. In PVA1, the content (S) was 0.5 mol%. The results of analyzing the obtained PVA are shown in Table 1.
Content of monomer unit having group represented by formula (1) (S: mol%)
= {(Peak area of β / 9) / (peak area of α + (peak area of β / 9))} × 100

[Synthesis Examples 2 to 21 and Comparative Synthesis Examples 1 to 15] Manufacture of PVA2 to PVA36 Polymerization conditions such as the amount of vinyl acetate and methanol, the type and addition amount of monomer A, the concentration of PVAc during saponification, and the vinyl acetate unit PVA2 to PVA36 were obtained in the same manner as in Synthesis Example 1 except that the saponification conditions such as the molar ratio of sodium hydroxide were changed as shown in Tables 1 and 2. Tables 1 and 2 show the results of analysis for each obtained PVA.
In Table 2, the content (S) * 2 includes the content of monomer units having a silyl group other than the monomer unit having a group represented by the formula (1).

[Example 1]
<Preparation of inorganic binder>
8 parts of PVA1 was dissolved in 92 parts of water to prepare an inorganic binder. The viscosity stability of the inorganic binder, the water resistance of the resulting film, and the water resistance and strength of the molded product were evaluated by the following evaluation methods. The results are shown in Table 3. In Table 3, * 1 indicates that PVA was not completely dissolved in the aqueous solution and thus could not be evaluated.

[Viscosity stability of inorganic binder]
The inorganic binder prepared above was left in a constant temperature bath at 20 ° C., and the viscosity immediately after the temperature of the solution reached 20 ° C. and the viscosity after 7 days were measured. A value obtained by dividing the viscosity immediately after the temperature of the solution reached 20 ° C. by the viscosity after 7 days (viscosity after 7 days / viscosity immediately after) was determined as a viscosity ratio (times), and determined according to the following criteria. . The results are shown in Table 3.
A: Less than 2.5 times B: 2.5 times or more and less than 3.5 times C: 3.5 times or more and less than 5.0 times D: 5.0 times or more, but the inorganic binder is not gelled E: Binder for inorganic substances loses fluidity and gels

[Water resistance of film]
The inorganic binder prepared above was cast at 20 ° C. to obtain a film having a thickness of 40 μm. The obtained film was cut into a size of 10 cm in length and 10 cm in width to prepare a test piece. After this test piece was immersed in distilled water at 20 ° C. for 24 hours, it was taken out (collected), the water adhering to the surface was wiped off with gauze, and the mass 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 mass at the time of water swelling by the mass at the time of drying was obtained, and this was taken as the degree of swelling (times), and was judged according to the following criteria. The results are shown in Table 3.
S: Less than 3.0 times A: 3.0 times or more and 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 10.0 times D: 10.0 times or more E: The immersed specimen cannot be collected

[Water resistance and strength of molded product]
<Preparation of measurement sample (molded body)>
A measurement sample (molded body) was produced as follows in accordance with the method described in JIS P8209. First, the inorganic binder prepared above was added to a slurry having a total inorganic fiber concentration of 4% including 70 parts of rock wool (density 0.16 g / cm ³ , fiber thickness 7 μm) and 30 parts of fully opened asbestos. It added so that the solid content of PVA might be 4 parts with respect to 100 parts of inorganic fiber, and it prepared by mixing in the test container, and also added water, and it adjusted so that the total solid content concentration might be 2%. A slurry was prepared. Next, this slurry was put into a standard sheet machine, water was further added to make the slurry concentration 1%, and paper was made in the same manner as in a normal paper making method. Thereafter, it was dehydrated, further dehydrated at 2 kg / cm ² for 1 minute with a sheet press, and then dried for 3 minutes in a 130 ° C. hot air dryer. The obtained inorganic fiberboard was left in a constant temperature and humidity chamber at 20 ° C. and 65% RH for 48 hours to obtain a measurement sample. The basis weight of the measurement sample was 125 g / m ² . Using this sample, water resistance and strength were measured by the following methods. The results are shown in Table 3.

(water resistant)
While putting water in a 500 mL beaker and stirring at 300 rpm at 40 ° C., the above measurement sample of 3 cm × 3 cm is put into this, and the time (minutes) until this sample disintegrates and disperses is measured, The determination was made according to the following criteria.
A: 15 minutes or more B: 12 minutes or more and less than 15 minutes C: 8 minutes or more and less than 12 minutes D: 5 minutes or more and less than 8 minutes E: Less than 5 minutes

(Strength)
The fracture length at room temperature was measured according to JISP-8113 and judged according to the following criteria. It shows that intensity | strength is so large that breaking length (km) is large.
A: 0.6 km or more B: 0.4 km or more and less than 0.6 km C: 0.2 km or more and less than 0.4 km D: 0.1 km or more and less than 0.2 km E: less than 0.1 km

[Examples 2 to 21 and Comparative Examples 1 to 15]
An inorganic binder was prepared and evaluated in the same manner as in Example 1 except that PVA shown in Table 3 was used instead of PVA1 used in Example 1. The results are also shown in Table 3.

  As shown in Table 3, the inorganic binders (PVA1 to 21) prepared in Examples 1 to 21 have sufficient water solubility and viscosity stability, and can obtain a highly water-resistant film. It turns out that the molded object which has water resistance and the outstanding intensity | strength can be produced. Here, if the viscosity stability is D or more, it is said that the viscosity stability is practically sufficient, and the other three items are C or more, and one or more of the three items is B or more. A better evaluation. Furthermore, PVA viscosity average polymerization degree (P), saponification degree, monomer unit structure, content rate (S), and product of viscosity average polymerization degree (P) and content rate (S) (P × S) are specified. The binders for inorganic substances of Examples 1, 9, 10, 15 to 18, 20, and 21 are particularly excellent in viscosity stability, water resistance of the obtained film, water resistance and strength of the formed article ( The viscosity stability is an evaluation of C or more, and the other three items are B or more, and two or more of the three items are evaluations of A or more). In Examples 2 to 8, 11 to 14, and 19, for example, it is understood that the viscosity stability, the water resistance of the obtained film, the water resistance and the strength of the formed article are slightly decreased. This is thought to be due to a decrease in viscosity average degree of polymerization (P) and quarrel and a difference in the structure of the monomer unit.

  On the other hand, when PVA does not satisfy the prescribed requirements (Comparative Examples 1 to 15), it does not have practically sufficient viscosity stability, the water resistance of the obtained film, the water resistance of the formed article, and the strength. It turns out that it falls. This is considered to be due to the difference in the structure of the monomer units and the product (P × S) of the viscosity average polymerization degree (P) and the content rate (S) being small or large.

  The binder for inorganic substances of the present invention has sufficient handleability and viscosity stability, and is excellent in the water resistance of the resulting film and the water resistance and strength of the resulting molded article. Therefore, the binder for inorganic substances of the present invention is suitably used as a binder for inorganic fibers and a binder for glass fibers.

Claims (7)

The binder for inorganic substances containing the vinyl alcohol polymer which contains the monomer unit which has group represented by following formula (1), and satisfy | fills following formula (I).

(In Formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ² is an alkoxyl group, an acyloxyl group, or a group represented by OM. M is a hydrogen atom, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group, each of which represents an alkyl group, an alkoxyl group or an acyloxyl group represented by R ^{1 to} R ^4. May be substituted with a substituent containing an oxygen atom or a nitrogen atom, m is an integer of 0 to 2. n is an integer of 3 or more, and there are a plurality of R ^{1 to} R ⁴ , respectively. In the case, a plurality of each R ^{1 to} R ⁴ independently satisfy the above definition.)
370 ≦ P × S ≦ 6,000 (I)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%) The binder for inorganic substances according to claim 1, wherein the vinyl alcohol polymer further satisfies the following formulas (II) and (III).
200 ≦ P ≦ 4,000 (II)
0.1 ≦ S ≦ 10 (III)
P: Viscosity average degree of polymerization S: Content of the monomer unit (mol%)   N in the said Formula (1) is an integer of 6-20, The binder for inorganic substances of Claim 1 or Claim 2. The binder for inorganic substances according to claim 1, wherein the monomer unit is represented by the following formula (2).

(In formula (2), the definitions of R ^{1 to} R ⁴ , m and n are the same as those in formula (1). X represents a direct bond, a divalent hydrocarbon group, an oxygen atom or a nitrogen atom 2. R ⁵ is a hydrogen atom or a methyl group.) The binder for inorganic substances according to claim 4, wherein X in the formula (2) is represented by the following formula (3).
-CO-NR ^6- * (3)
(In the formula (3), R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. * Indicates a bonding position with the group represented by the above formula (1).) The binder for inorganic substances according to claim 5, wherein R ⁶ in the formula (3) is a hydrogen atom, and n in the formula (2) is an integer of 3 to 12.   The binder for inorganic substances according to any one of claims 1 to 6, which is used as a binder for inorganic fibers.