JP5937497B2 - Alkyl-modified vinyl alcohol polymer solution and method for producing the same - Google Patents

Description

  The present invention relates to an alkyl-modified vinyl alcohol polymer solution and a method for producing the same.

  A vinyl alcohol polymer (hereinafter sometimes abbreviated as “PVA”) is a few crystalline water-soluble polymers, and has excellent film-forming properties, interfacial properties, and strength properties. For this reason, PVA is widely used as a raw material for thickeners, paper coating agents, adhesives, fiber processing agents, binders, emulsion stabilizers, films, fibers and the like. Moreover, in order to improve the specific performance of PVA, development of modified PVA by controlling crystallinity, introducing functional groups, and the like has been performed.

  Alkyl-modified PVA, which is one of such modified PVAs, is known to exhibit an alkyl group interaction in an aqueous solvent and give a high viscosity solution. For this reason, alkyl-modified PVA is useful as a thickener for paints and adhesives, and alkyl-modified PVA containing various monomer units has been developed (Japanese Patent Laid-Open No. 2008-291120 and Japanese Patent Laid-Open No. Hei 10-). 338714). Such an alkyl-modified PVA solution is required to have a sufficiently high viscosity as well as a high transparency. However, the alkyl-modified PVA has low solubility in water, and in order to increase transparency, there is a disadvantage that the concentration in the aqueous solution cannot be increased so much that even if the concentration of the alkyl-modified PVA is lowered, a sufficient viscosity can be obtained. It is required to be able to demonstrate.

JP 2008-291120 A JP 10-338714 A

  The present invention has been made based on the above circumstances, and an object thereof is to provide an alkyl-modified PVA solution having high transparency and high viscosity even when the concentration of the alkyl-modified PVA is lowered.

（式（Ｉ）中、Ｒ^１は、炭素数２又は３のアルキレン基である。Ｒ^２及びＲ^３は、それぞれ独立して、単結合又はカルボニル基である。Ｘ^１は、水素原子又は炭素数１〜３０の疎水基である。Ｘ^２は、水素原子又は炭素数１〜３０の有機基である。ｍは、３以上３００以下の整数である。複数存在するＲ^１は、それぞれ独立して上記定義を満たす。但し、Ｒ^２が単結合の場合、Ｘ^２が水素原子である場合はない。Ｒ^３が単結合の場合、Ｘ^１が水素原子である場合はない。） The present invention made to achieve the above object
Containing an alkyl-modified vinyl alcohol polymer, a surfactant and water,
The alkyl-modified vinyl alcohol polymer contains a monomer unit having an alkyl group having 5 to 29 carbon atoms, the content of the monomer unit is 0.05 mol% or more and 5 mol% or less, and The saponification degree of the alkyl-modified vinyl alcohol polymer is 20 mol% or more and 99.99 mol% or less,
The surfactant is an alkyl-modified vinyl alcohol polymer solution that is a compound represented by the following formula (I).

(In Formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or a carbon atom. A hydrophobic group having 1 to 30. X ² is a hydrogen atom or an organic group having 1 to 30 carbon atoms, m is an integer of 3 to 300. A plurality of R ¹ are independently selected. However, when R ² is a single bond, X ² is not a hydrogen atom, and when R ³ is a single bond, X ¹ is not a hydrogen atom.)

The alkyl-modified PVA solution contains a surfactant having the specific structure. This surfactant has a hydrophilic oxyalkylene group and has a structure in which a hydrophobic group X ¹ and an organic group X ² are located at both ends, and is compatible with the specific alkyl-modified PVA and water. Excellent. Moreover, it is thought that the hydrophobic interaction between the alkyl groups which the said alkyl-modified PVA has can be promoted by interposition of the group of the said both ends which the said surfactant has. As a result, the alkyl-modified PVA solution is excellent in transparency and becomes an alkyl-modified PVA solution having a high viscosity even when the concentration of the alkyl-modified PVA is low.

X ¹ and X ² are preferably each independently a hydrogen atom, an alkyl group having 1 to 29 carbon atoms, or an alkenyl group having 2 to 29 carbon atoms. When the X ¹ and X ² are the specific group, the hydrophobic interaction between the above alkyl groups can be further promoted, and the alkyl-modified PVA solution can improve transparency and viscosity. .

（式（ＩＩ）中、Ｒ^４は、炭素数５〜２９のアルキル基である。Ｒ^５は、水素原子又は炭素数１〜８のアルキル基である。） The monomer unit is preferably represented by the following formula (II).

(In formula (II), R ⁴ is an alkyl group having ^{5 to} 29 carbon atoms. R ⁵ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

  The said alkyl-modified PVA solution can exhibit the said effect more effectively because the said monomer unit has the said specific structure.

（式（ＩＩＩ）中、Ｒ^４及びＲ^５の定義は、上記式（ＩＩ）と同様である。） The alkyl-modified vinyl alcohol polymer is preferably obtained by saponifying a copolymer of an unsaturated monomer represented by the following formula (III) and a vinyl ester monomer.

(In formula (III), the definitions of R ⁴ and R ⁵ are the same as in formula (II) above.)

  Since the alkyl-modified PVA contained in the alkyl-modified PVA solution is obtained by saponifying the copolymer of the specific monomer, adjustment of the saponification degree of the alkyl-modified PVA becomes easy, The transparency of the alkyl-modified PVA solution can be further increased.

  The viscosity average polymerization degree of the alkyl-modified vinyl alcohol polymer is preferably 100 or more and 5,000 or less. By making the viscosity average polymerization degree of the alkyl-modified PVA within the above range, the alkyl-modified PVA solution can enhance transparency.

  The mass ratio of the surfactant to the alkyl-modified PVA is preferably from 0.1 / 99.9 to 40/60. By setting the mass ratio of the surfactant and the alkyl-modified PVA within the above range, the alkyl-modified PVA solution can further increase transparency and viscosity.

  The concentration of the alkyl-modified PVA is preferably 0.5% by mass or more and 50% by mass or less. By making the density | concentration of the said alkyl modified PVA into the said range, the said alkyl modified PVA solution can exhibit the said effect more effectively.

（式（Ｉ）中、Ｒ^１は、炭素数２又は３のアルキレン基である。Ｒ^２及びＲ^３は、それぞれ独立して、単結合又はカルボニル基である。Ｘ^１は、水素原子又は炭素数１〜３０の疎水基である。Ｘ^２は、水素原子又は炭素数１〜３０の有機基である。ｍは、３以上３００以下の整数である。複数存在するＲ^１は、それぞれ独立して上記定義を満たす。但し、Ｒ^２が単結合の場合、Ｘ^２が水素原子である場合はない。Ｒ^３が単結合の場合、Ｘ^１が水素原子である場合はない。） The method for producing the alkyl-modified PVA solution of the present invention includes:
A step of mixing an alkyl-modified vinyl alcohol polymer, a surfactant and water;
The alkyl-modified vinyl alcohol polymer contains a monomer unit having an alkyl group having 5 to 29 carbon atoms, the content of the monomer unit is 0.05 mol% or more and 5 mol% or less, and The saponification degree of the alkyl-modified vinyl alcohol polymer is 20 mol% or more and 99.99 mol% or less,
In the method for producing an alkyl-modified vinyl alcohol polymer solution, the surfactant is a compound represented by the following formula (I).

(In Formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or a carbon atom. A hydrophobic group having 1 to 30. X ² is a hydrogen atom or an organic group having 1 to 30 carbon atoms, m is an integer of 3 to 300. A plurality of R ¹ are independently selected. However, when R ² is a single bond, X ² is not a hydrogen atom, and when R ³ is a single bond, X ¹ is not a hydrogen atom.)

  According to the method for producing the alkyl-modified PVA solution, it is possible to easily produce an alkyl-modified PVA solution having high transparency and high viscosity even when the concentration of the alkyl-modified PVA is lowered.

  The alkyl-modified PVA solution in a gel state is also included in the range of the alkyl-modified PVA solution.

  Here, the “organic group” refers to a group containing at least one carbon atom.

  The alkyl-modified PVA solution of the present invention is excellent in transparency and can exhibit high viscosity even when the concentration of the alkyl-modified PVA is lowered. Therefore, the alkyl-modified PVA solution can be suitably used as a thickener such as an adhesive or a paint. Further, according to the method for producing the alkyl-modified PVA solution, an alkyl-modified PVA solution having high transparency and high viscosity can be easily obtained.

  Hereinafter, embodiments of the alkyl-modified PVA solution of the present invention will be described in detail.

<Alkyl-modified PVA solution>
The alkyl-modified PVA solution of the present invention contains an alkyl-modified PVA, a surfactant and water. In addition, the alkyl-modified PVA solution may contain an optional component as long as the gist of the present invention is not impaired. Hereinafter, these components will be described in detail.

(Alkyl-modified PVA)
The alkyl-modified PVA contained in the alkyl-modified PVA solution of the present invention contains monomer units having an alkyl group having 5 to 29 carbon atoms. That is, the alkyl-modified PVA is a copolymer containing a monomer unit having an alkyl group having 5 to 29 carbon atoms and a vinyl alcohol monomer unit, and further contains other monomer units. You may contain. When the number of carbon atoms of the alkyl group is less than 5, the hydrophobic interaction between the alkyl groups is not sufficiently exhibited, so that the viscosity of the alkyl-modified PVA solution is lowered. On the other hand, when the carbon number of this alkyl group exceeds 29, the water solubility of the said alkyl modified PVA falls and the transparency of the said alkyl modified PVA solution falls. As carbon number of the said alkyl group, from a viewpoint of improving transparency, 5-24 are preferable, 5-20 are more preferable, 7-20 are more preferable, and 9-20 are especially preferable.

As the monomer unit having an alkyl group having 5 to 29 carbon atoms,
Monomer units derived from α-olefins such as 1-octene and 1-decene;
Monomer units derived from vinyl ethers such as pentyl vinyl ether, octyl vinyl ether, nonyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether;
A monomer unit represented by the following formula (IV) is preferable, and a monomer unit in which R ³ is an alkyl group having 5 to 24 carbon atoms is more preferable.

In the formula (II), ^{R 4} is an alkyl group having 5 to 29 carbon atoms. R ⁵ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

Examples of the alkyl group having 5 to 29 carbon atoms represented by R ⁴ include a pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, pentadecyl group, octadecyl group, nonadecyl group, Examples include a hexacosyl group. Among these, from the viewpoint that the transparency and viscosity of the alkyl-modified PVA solution can be further increased, an alkyl group having 5 to 24 carbon atoms is preferable, an alkyl group having 5 to 20 carbon atoms is more preferable, and a carbon number having 7 to 20 carbon atoms. An alkyl group is more preferable, and an alkyl group having 9 to 20 carbon atoms is particularly preferable.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R ⁵ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Of these, a methyl group is preferred.

R ⁵ is preferably a hydrogen atom or a methyl group from the viewpoint of ease of synthesis and the like.

The alkyl group represented by R ⁴ and R ⁵ may have a substituent such as a halogen atom as long as the gist of the present invention is not impaired. Preferably not.

  It is important that the content of the monomer unit having an alkyl group having 5 to 29 carbon atoms in the alkyl-modified PVA is from 0.05 mol% to 5 mol%, and from 0.05 mol% to 2 mol. % Or less, preferably 0.1 mol% or more and 2 mol% or less, more preferably 0.2 mol% or more and 1 mol% or less. In the present specification, the content of the monomer unit having an alkyl group having 5 to 29 carbon atoms includes an alkyl group having 5 to 29 carbon atoms in the number of moles of all structural units constituting the alkyl-modified PVA. It is the ratio of the number of moles of monomer units.

  When the content of the monomer unit having an alkyl group having 5 to 29 carbon atoms exceeds 5 mol%, the proportion of the hydrophobic group contained in one molecule of the alkyl-modified PVA is increased, and the water-solubility of the alkyl-modified PVA is increased. Decreases. On the other hand, when the content of the monomer unit having an alkyl group having 5 to 29 carbon atoms is less than 0.05 mol%, the water content of the alkyl-modified PVA is excellent, but is included in the alkyl-modified PVA. The number of alkyl groups is small, and physical properties such as high viscosity based on alkyl modification do not appear.

The content of the monomer unit having an alkyl group having 5 to 29 carbon atoms can be determined from proton NMR of the alkyl-modified vinyl ester polymer that is a precursor of the alkyl-modified PVA. Specifically, after reprecipitation purification of the alkyl-modified vinyl ester polymer with n-hexane / acetone 3 times or more sufficiently, it is dried at 50 ° C. under reduced pressure for 2 days to prepare a sample for analysis. To do. This sample is dissolved in CDCl ₃ and measured at room temperature using 500 MHz proton NMR (JEOL GX-500).

In this case, for example, the alkyl-modified vinyl ester polymer does not contain an alkyl-modified monomer unit other than the monomer unit represented by the formula (IV), and R ³ is linear. Further, when R ⁴ is a hydrogen atom, it can be calculated by the following method. That is, the peak α (4.7 to 5.2 ppm) derived from the main chain methine of the alkyl-modified vinyl ester polymer and the peak β (0.8 to 1.0 ppm derived from the terminal methyl group of the alkyl group R ³ ). ), The content S of the monomer unit represented by the above formula (IV) is calculated using the following formula.
S (mol%)
= {(Number of protons of β / 3) / (number of protons of α + (number of protons of β / 3))} × 100

  The viscosity average polymerization degree of the alkyl-modified PVA contained in the alkyl-modified PVA solution is preferably 100 or more and 5,000 or less, more preferably 500 or more and 2,700 or less, and more preferably 1,000 or more and 2,300 or less. preferable. The viscosity average degree of polymerization may be simply referred to as the degree of polymerization. When the degree of polymerization exceeds 5,000, the productivity of the alkyl-modified PVA may be reduced. Conversely, when the degree of polymerization is less than 100, the viscosity of the alkyl-modified PVA solution may be reduced.

This viscosity average degree of polymerization (P) is measured according to JIS-K6726: 1994. That is, after re-saponifying and purifying the alkyl-modified PVA, it is obtained by the following formula from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30 ° C.
P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  The saponification degree of the alkyl-modified PVA contained in the alkyl-modified PVA solution is 20 mol% to 99.99 mol%, preferably 40 mol% to 99.95 mol%, preferably 70 mol% to 99.9 mol. % Or less is more preferable. When the degree of saponification is less than 20 mol%, the water solubility of the alkyl-modified PVA decreases, and as a result, the transparency of the alkyl-modified PVA solution decreases. On the contrary, if the degree of saponification exceeds 99.99 mol%, production of alkyl-modified PVA becomes difficult, which is not practical. The saponification degree of the alkyl-modified PVA is measured according to JIS-K6726: 1994.

  The concentration of the alkyl-modified PVA in the alkyl-modified PVA solution is not particularly limited, but is preferably 0.5% by mass to 50% by mass, more preferably 0.8% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass. % Or less is more preferable.

(Method for producing alkyl-modified PVA)
The method for producing the alkyl-modified PVA is not particularly limited, but an alkyl-modified vinyl ester-based polymer obtained by copolymerizing an unsaturated monomer represented by the following formula (III) and a vinyl ester-based monomer. A method of saponifying the polymer (copolymer) is preferred. Since the alkyl-modified PVA contained in the alkyl-modified PVA solution is obtained by saponifying the copolymer of the specific monomer, adjustment of the saponification degree of the alkyl-modified PVA becomes easy and transparent. The sex and the like can be further enhanced. Here, the copolymerization is preferably performed in an alcohol solvent or without a solvent.

In the above formula (III), the definitions of R ⁴ and R ⁵ are the same as in the above formula (II).

  Examples of the unsaturated monomer represented by the above formula (III) include N-pentylacrylamide, N-octylacrylamide, N-decylacrylamide, N-dodecylacrylamide, N-octadecylacrylamide, N-hexacosylacrylamide, N-pentyl methacrylamide, N-octyl methacrylamide, N-decyl methacrylamide, N-dodecyl methacrylamide, N-octadecyl methacrylamide, N-hexacosyl methacrylamide and the like can be mentioned. Of these, N-octadecylacrylamide, N-pentylmethacrylamide, N-octylmethacrylamide, N-decylmethacrylamide, N-dodecylmethacrylamide, N-octadecylmethacrylamide, and N-hexacosylmethacrylamide are preferred, N -Octadecyl acrylamide, N-dodecyl methacrylamide, and N-octadecyl methacrylamide are more preferable, and N-octadecyl acrylamide and N-octadecyl methacrylamide are more preferable.

  Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, and palmitic acid. Examples include vinyl, vinyl stearate, vinyl oleate, vinyl benzoate and the like. Of these, vinyl acetate is preferred.

In the copolymerization of the unsaturated monomer represented by the above formula (III) and the vinyl ester monomer, other monomers may be copolymerized within a range not impairing the gist of the present invention. Examples of other monomers that can be used include α-olefins such as ethylene, propylene, n-butene, and isobutylene;
Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, nonyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether;
Nitriles such as acrylonitrile and methacrylonitrile;
Vinyl halides such as vinyl chloride and vinyl fluoride;
Vinylidene halides such as vinylidene chloride and vinylidene fluoride;
Allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride;
Vinylsilyl compounds such as vinyltrimethoxysilane;
And isopropenyl acetate.

In addition, in the copolymerization of the unsaturated monomer represented by the formula (III) and the vinyl ester monomer, the purpose of the present invention is to adjust the degree of polymerization of the copolymer obtained. You may add a chain transfer agent in the range which does not impair the meaning. Examples of the chain transfer agent include aldehydes such as acetaldehyde and propionaldehyde;
Ketones such as acetone and methyl ethyl ketone;
Mercaptans such as 2-hydroxyethanethiol;
Halogenated hydrocarbons such as trichlorethylene and perchlorethylene;
And phosphinic acid salts such as sodium phosphinate monohydrate. Of these, aldehydes and ketones are preferable.

  The addition amount of the chain transfer agent can be determined according to the chain transfer constant of the chain transfer agent to be added and the degree of polymerization of the target alkyl-modified vinyl ester polymer, and thus the degree of polymerization of the alkyl-modified PVA. In general, the content is preferably 0.1% by mass or more and 10% by mass or less based on the vinyl ester monomer.

  The temperature employed when copolymerizing the unsaturated monomer represented by the above formula (III) and the vinyl ester monomer is preferably 0 ° C to 200 ° C, preferably 30 ° C to 140 ° C. Is more preferable. When the copolymerization temperature is lower than 0 ° C., it is difficult to obtain a sufficient polymerization rate. Moreover, when the temperature which superposes | polymerizes is higher than 200 degreeC, it is difficult to obtain the alkyl modified PVA which satisfies the content rate of the monomer unit which has an alkyl group prescribed | regulated by this invention. As a method for controlling the temperature employed in the copolymerization to 0 ° C. to 200 ° C., for example, by controlling the polymerization rate, the heat generated by the polymerization reaction and the heat radiation from the surface of the reactor are balanced. And a method of controlling by an external jacket using an appropriate heat medium. Among these methods, the method of controlling by an external jacket using an appropriate heat medium is preferable from the viewpoint of safety.

  Examples of the polymerization method used for the copolymerization of the unsaturated monomer represented by the formula (III) and the vinyl ester monomer include batch polymerization, semi-batch polymerization, continuous polymerization, and semi-continuous. Polymerization etc. are mentioned. As the polymerization method, known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be used. Among these, a bulk polymerization method in which polymerization is performed in a solvent-free or alcohol-based solvent or a solution polymerization method is preferably employed, and an emulsion polymerization method is employed for the purpose of producing a copolymer having a high degree of polymerization. .

  Examples of the alcohol solvent include methanol, ethanol, n-propanol, and the like, but are not limited thereto. These solvents can be used as a mixture of two or more.

  The initiator used for the copolymerization of the unsaturated monomer represented by the above formula (III) and the vinyl ester monomer may be a conventionally known azo initiator or peroxide according to the polymerization method. A physical initiator, a redox initiator, or the like can be used.

  Examples of the azo initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2, 4-dimethylvaleronitrile) and the like.

Examples of the peroxide-based initiator include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate;
Perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, t-butyl peroxydecane;
Examples thereof include acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and the like. Furthermore, the initiator can be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like to form an initiator.

  Examples of the redox initiator include a combination of the above peroxide and a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, Rongalite, and the like.

  In addition, when copolymerization of the unsaturated monomer represented by the above formula (III) and the vinyl ester monomer is performed at a high temperature, coloring of PVA caused by decomposition of the vinyl ester monomer Etc. may be seen. In this case, it is preferable to add an antioxidant such as tartaric acid to the polymerization system in an amount of about 1 to 100 ppm based on the vinyl ester monomer for the purpose of preventing coloring.

  For the saponification reaction of the alkyl-modified vinyl ester copolymer obtained by the above copolymerization, a known basic catalyst such as sodium hydroxide, potassium hydroxide, sodium methoxide or acidic catalyst such as p-toluenesulfonic acid is used. The alcoholysis reaction or hydrolysis reaction used can be applied.

  Examples of the solvent that can be used in the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene and toluene. It is done. In addition, these solvents can be used individually or in combination of 2 or more types.

  As the saponification reaction, a method of using methanol or a methanol / methyl acetate mixed solution as a solvent and sodium hydroxide as a catalyst is simple and preferable.

(Surfactant)
The surfactant contained in the alkyl-modified PVA solution is a compound represented by the following formula (I).

In formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or a hydrophobic group having 1 to 30 carbon atoms. X ² is a hydrogen atom or an organic group having 1 to 30 carbon atoms. m is an integer of 3 to 300. A plurality of R ¹ satisfy the above definition independently of each other. However, when R ² is a single bond, X ² is not a hydrogen atom. When R ³ is a single bond, X ¹ is not a hydrogen atom.

The surfactant has a hydrophilic oxyalkylene group, and has a structure in which the hydrophobic group X ¹ and the organic group X ² are located at both ends, and is compatible with the specific alkyl-modified PVA and water. Excellent. Moreover, it is thought that the hydrophobic interaction between the alkyl groups which the said alkyl-modified PVA has can be promoted by interposition of the group of the said both ends which the said surfactant has. As a result, the alkyl-modified PVA solution is excellent in transparency and becomes an alkyl-modified PVA solution having a high viscosity even when the concentration of the alkyl-modified PVA is low.

The hydrophobic group having 1 to 30 carbon atoms represented by X ^1, preferably a hydrocarbon group having 1 to 30 carbon atoms, Among these, linear or branched alkyl group having 1 to 30 carbon atoms, A linear or branched alkenyl group having 2 to 30 carbon atoms is more preferred.

Examples of the linear or branched alkyl group having 1 to 30 carbon atoms include:
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, i-pentyl group, t-pentyl group , Neo-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group N-tetradecyl group, n-pentadecyl group, 2-hexyloctyl group, n-hexadecyl group, 2-hexyldecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, n- Henicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, n-pentacosyl group, n-hexacosyl group, n-heptacosyl group, n-octacosyl group, n Nonacosyl group, triacontyl group and the like. Among these, n-heptadecyl group is preferable.

Examples of the linear or branched alkenyl group having 2 to 30 carbon atoms include:
Ethenyl group, n-propenyl group, i-propenyl group, n-butenyl group, i-butenyl group, sec-butenyl group, t-butenyl group, n-pentenyl group, n-hexenyl group, n-octenyl group, n- Nonenyl group, n-decenyl group, n-dodecenyl group, n-tetradecenyl group, n-hexadecenyl group, n-heptadecenyl group, n-octadecenyl group, n-icosenyl group, n-docosenyl group, n-tetracocenyl group, n- Examples include a hexacocenyl group and an n-nonacosenyl group. Among these, n-heptadecenyl group is preferable.

The organic group having 1 to 30 carbon atoms represented by X ^2, preferably hydrophobic group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 30 carbon atoms, Among these, 1 carbon atoms 30 straight-chain or branched alkyl groups and 2-30 straight-chain or branched alkenyl groups are more preferred. Examples of these groups include the same groups as the groups exemplified as X ¹ above. In addition, a preferable group as X ^{2 is the same} as the preferable group of X ¹ described above.

The number of carbon atoms of the ^{X 1} and ^{X 2,} preferably from 4 to 24, more preferably 8 to 22, further preferably 12 to 20. The number of carbon atoms within the above range, the interaction between the alkyl group and X ¹ and X ² of the alkyl-modified PVA is considered to increase, as a result, the viscosity of the alkyl-modified PVA is enhanced.

Examples of the alkylene group having 2 or 3 carbon atoms represented by R ¹ include an ethylene group, a 1,1-propanediyl group, and a 1,2-propanediyl group.

As the ^{R 2} and ^{R 3,} a carbonyl group is preferred.

  From the viewpoint of increasing the viscosity of the alkyl-modified PVA solution, m is preferably an integer of 10 or more, 300 or less, more preferably an integer of 25 or more and 300 or less, still more preferably an integer of 50 or more and 300 or less, and 100 or more. An integer of 250 or less is particularly preferable.

The surfactant is not particularly limited as long as it is a compound represented by the above formula (I).
Polyethylene glycol, polypropylene glycol;
Polyethylene glycol-polypropylene glycol diblock copolymer;
The hydrogen atom of the hydroxyl group of both ends, such as a polyethylene glycol-polypropylene glycol-polyethylene glycol and a polypropylene glycol-polyethylene glycol-polypropylene glycol triblock copolymer, has an acyl group having 2 to 31 carbon atoms and / or 1 to 30 carbon atoms. Examples thereof include a diester, a diether or an ester ether substituted with a hydrocarbon group. Among these, from the viewpoint of further enhancing the transparency of the alkyl-modified PVA solution and the viscosity when the alkyl-modified PVA is at a low concentration, polyethylene glycol diesters and polypropylene glycol diesters are preferred. Di (n-octadecanoic acid) ester and di (n-octadecanoic acid) ester of polypropylene glycol are more preferable.

  The mass ratio of the surfactant contained in the alkyl-modified PVA solution to the alkyl-modified PVA (mass of surfactant / mass of alkyl-modified PVA) is preferably 0.1 / 99.9 or more and 40/60 or less. 3/97 or more and 35/65 or less are more preferable, 7/93 or more and 30/70 or less are more preferable, and 10/90 or more and 25/75 or less are particularly preferable. By setting the mass ratio of the surfactant and the alkyl-modified PVA within the above range, the alkyl-modified PVA solution can further improve transparency and viscosity. When the said mass ratio is less than 0.1 / 99.9, there exists a possibility that the transparency and viscosity of the said alkyl-modified PVA solution may fall. Conversely, if the mass ratio exceeds 40/60, the transparency of the alkyl-modified PVA solution may be reduced.

(Optional component)
[Additive]
In addition to the alkyl-modified PVA, the specific surfactant and water, the alkyl-modified PVA solution contains additives such as various plasticizers, antifoaming agents, ultraviolet absorbers, fillers, pH adjusters, and water resistance agents. You may contain in the range which does not impair the meaning of invention.

[Other water-soluble polymers]
The alkyl-modified PVA solution is a known various PVA other than the above-mentioned alkyl-modified PVA contained in the alkyl-modified PVA solution, starch, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, within a range that does not impair the spirit of the present invention. Other water-soluble polymers such as hydroxypropylcellulose may be contained. The blending amount of these other water-soluble polymers is preferably 50 parts by mass or less with respect to 100 parts by mass of the alkyl-modified PVA contained in the alkyl-modified PVA solution.

(Use etc.)
The alkyl-modified PVA solution is highly transparent and has a high viscosity even when the concentration of the alkyl-modified PVA is lowered. Therefore, the alkyl-modified PVA solution can be suitably used as a temperature-sensitive binder, a gelling agent, a temperature-sensitive adhesive, a thickener, and the like. Specifically, for example, paper coating agents; internal sizing agents; fiber processing agents; dyes; glass fiber coating agents; metal and glass surface coating agents; coating agents such as anti-fogging agents; wood, paper, aluminum Adhesives such as foils and plastics; Non-woven fabric binders; Fibrous binders; Binders for building materials such as gypsum boards and fiberboards; Thickeners for various emulsion adhesives; Additives for urea resin adhesives; Additions for cement and mortar Agents; Hot-melt adhesives; Various adhesives such as pressure-sensitive adhesives; Dispersants for emulsion polymerization of various ethylenically unsaturated monomers such as ethylene, vinyl acetate and vinyl chloride; Dispersing pigments in paints, adhesives, etc. Stabilizers for dispersion polymerization of various ethylenically unsaturated monomers such as vinyl chloride, vinylidene chloride, styrene, (meth) acrylic acid, vinyl acetate; fibers, films, Can be used as a component constituting a soil stabilizer and the like; hydrophilic agent to the hydrophobic resin; soil improvement agent over preparative, pipes, tubes, water-soluble fibers, molded products such as interim film.

<Method for producing alkyl-modified PVA solution>
The method for producing the alkyl-modified PVA solution of the present invention includes:
A step of mixing an alkyl-modified vinyl alcohol polymer, a surfactant and water;
The alkyl-modified vinyl alcohol polymer contains a monomer unit having an alkyl group having 5 to 29 carbon atoms, the content of the monomer unit is 0.05 mol% or more and 5 mol% or less, and The saponification degree of the alkyl-modified vinyl alcohol polymer is 20 mol% or more and 99.99 mol% or less,
In the production method, the surfactant is a compound represented by the following formula (I).

In formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or a hydrophobic group having 1 to 30 carbon atoms. X ² is a hydrogen atom or an organic group having 1 to 30 carbon atoms. m is an integer of 3 to 300. A plurality of R ¹ satisfy the above definition independently of each other. However, when R ² is a single bond, X ² is not a hydrogen atom. When R ³ is a single bond, X ¹ is not a hydrogen atom.

  According to the method for producing the alkyl-modified PVA solution, a solution having high transparency and a high viscosity can be easily obtained even if the concentration of the alkyl-modified PVA is lowered. The details of this alkyl-modified PVA, surfactant and the like are as described above.

  The method of mixing the alkyl-modified PVA, the surfactant and water is not particularly limited, and the alkyl-modified PVA may be added to a mixture of the surfactant and water, or the surfactant may be added to the alkyl-modified PVA aqueous solution. An agent may be added. In addition, in order to improve solubility, you may stir, heating. As the temperature of the solution during the heating, for example, 80 ° C. or more and 95 ° C. or less is adopted.

  Hereinafter, the present invention will be described in detail by way of examples and comparative examples. In the following examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

  PVA (alkyl-modified PVA and non-modified PVA) obtained by the following production examples was evaluated according to the following method.

[Modification rate]
The modification rate of each PVA (the content of monomer units having an alkyl group in PVA) was determined by the method using proton NMR described above.

[Degree of polymerization]
The viscosity average degree of polymerization of each PVA was determined by the method described in JIS-K6726: 1994.

[Saponification degree]
The degree of saponification of each PVA was determined by the method described in JIS-K6726: 1994.

<Manufacture of PVA>
[Production Example 1] (Production of PVA1)
A 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, comonomer dropping port and initiator addition port was charged with 750 g of vinyl acetate, 250 g of methanol and 1.1 g of N-octadecyl methacrylamide and bubbling nitrogen. Then, the system was purged with nitrogen for 30 minutes. Further, a comonomer solution in which N-octadecylmethacrylamide was dissolved in methanol to a concentration of 5% was prepared 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., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. Add a delay solution dropwise, polymerize at 60 ° C. for 3 hours while keeping the monomer composition (ratio of vinyl acetate and N-octadecyl methacrylamide) in the polymerization solution constant, and then stop the polymerization by cooling. did. The total amount (preparation + addition) of the comonomer (N-octadecylmethacrylamide) used was 4.8 g. The polymerization rate of vinyl acetate was 40%. The solid content concentration when the polymerization was stopped was 29.9%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 35%) of an alkyl-modified vinyl ester polymer (alkyl-modified PVAc). Furthermore, 27.9 g of an alkali solution (10% methanol solution of sodium hydroxide) was added to 771.4 g of an alkyl-modified PVAc methanol solution prepared by adding methanol thereto (200.0 g of alkyl-modified PVAc in the solution). Saponification was performed. Here, the alkyl-modified PVAc concentration in the saponification solution was 25%, and the molar ratio of sodium hydroxide to vinyl acetate units in the alkyl-modified PVAc was 0.03. A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification, and then 500 g of methyl acetate was added to leave the remaining alkali. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2,000 g of methanol was added thereto, and the mixture was allowed to stand and washed at room temperature for 3 hours. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain alkyl-modified PVA (PVA1).

[Production Examples 2 to 18] (Production of PVA 2 to 18)
Charge amount of vinyl acetate and methanol, polymerization conditions such as type and addition amount of unsaturated monomer having alkyl group used during polymerization, polymerization rate of vinyl acetate, concentration of alkyl-modified PVAc during saponification, relative to vinyl acetate unit Various alkyl-modified PVAs (PVA 2-18) were produced in the same manner as in Production Example 1 except that the saponification conditions such as the molar ratio of sodium hydroxide were changed as shown in Table 1.

[Production Example 19] (Production of PVA19)
A 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet tube and initiator addition port was charged with 750 g of vinyl acetate, 250 g of methanol, and 57.3 g of octadecyl vinyl ether, and the system was added for 30 minutes while bubbling nitrogen. Was replaced with nitrogen. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 1.0 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. After polymerization at 60 ° C. for 2 hours, the polymerization was stopped by cooling. The polymerization rate of vinyl acetate was 40%. The solid content concentration when the polymerization was stopped was 30.4%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 35%) of an alkyl-modified vinyl ester polymer (alkyl-modified PVAc). Furthermore, 7.0 g of an alkali solution (sodium hydroxide in 10% methanol) was added to 792.9 g of an alkyl-modified PVAc methanol solution (200.0 g of alkyl-modified PVAc in the solution) prepared by adding methanol. Saponification was performed. Here, the alkyl-modified PVAc concentration in the saponification solution was 25%, and the molar ratio of sodium hydroxide to vinyl acetate units in the alkyl-modified PVAc was 0.0075. A gel-like product was formed in about 12 minutes after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2,000 g of methanol was added thereto, and the mixture was allowed to stand and washed at room temperature for 3 hours. After the above washing operation was repeated three times, the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain alkyl-modified PVA (PVA19).

[Production Example 20] (Production of PVA20)
900 g of vinyl acetate and 100 g of methanol were charged into a 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet tube and initiator addition port, and the system was purged with nitrogen for 30 minutes while bubbling nitrogen. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to start polymerization, and polymerization was performed at 60 ° C. for 3 hours. Then, the polymerization was stopped by cooling. The polymerization rate of vinyl acetate was 35%. The solid content concentration when the polymerization was stopped was 31.0%. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 30%) of polyvinyl acetate (PVAc). Furthermore, saponification was performed by adding 27.9 g of an alkaline solution (sodium hydroxide in 10% methanol) to 971.1 g of PVAc methanol solution prepared by adding methanol thereto (200.0 g of PVAc in the solution). It was. Here, the PVAc concentration of the saponification solution was 20%, and the molar ratio of sodium hydroxide to vinyl acetate units in PVAc was 0.03. A gel-like product was formed in about 1 minute after the addition of the alkaline solution. This was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to proceed with saponification, and then 500 g of methyl acetate was added to leave the remaining alkali. Neutralized. After confirming that the neutralization was completed using a phenolphthalein indicator, a white solid was obtained by filtration, 2,000 g of methanol was added thereto, and the mixture was allowed to stand and washed at room temperature for 3 hours. After repeating the above washing operation three times, the white solid obtained by centrifugal drainage was allowed to stand in a dryer at 65 ° C. for 2 days to obtain unmodified PVA (PVA20).

<Preparation of alkyl-modified PVA solution>
[Example 1]
To a 300 mL separable flask equipped with a stirrer, 98.5 g of water and 0.15 g of polyethylene glycol n-octadecanoic acid diester (surfactant A in Table 2 below) as a surfactant were added and dissolved. Next, 1.5 g of PVA1 was added at room temperature, the temperature was raised to 90 ° C., and the mixture was stirred for 1.5 hours to be dissolved. Then, it cooled to room temperature and obtained the PVA solution which contains PVA1 by the density | concentration of 1.5 mass%.

[Examples 2 to 23 and Comparative Examples 1 to 4]
The concentration of each PVA was 1.5% by mass in the same manner as in Example 1 except that the types of PVA and surfactant used, and the mass ratio between the surfactant and PVA were changed as shown in Table 3. A PVA solution was prepared. Table 2 shows the types of surfactants used. The surfactants A to E in Table 2 are surfactants represented by the formula (I).

<Evaluation>
The alkyl-modified PVA solution was evaluated for solubility and solution by the following methods. The evaluation results are shown in Table 3. In Table 3, “(* 1)” indicates that no surfactant was added. Further, “(* 2)” in Table 3 indicates that PVA was not completely dissolved and could not be evaluated.

[Solution evaluation]
(Viscosity increase)
The viscosity (a) (mPa · s) of the alkyl-modified PVA solution prepared in the above example was measured using a BH viscometer under the conditions of a rotor rotation speed of 2 rpm and 20 ° C. Moreover, the viscosity (b) of the alkyl-modified PVA solution of the same density | concentration which does not contain surfactant was measured on the same conditions. The viscosity ratio (a / b) was calculated from these measured values, and was used as the degree of increase in viscosity.

(Transparency at 20 ° C)
The transparency at 20 ° C. of the PVA solution obtained in the above examples was visually evaluated. In addition, when the following evaluation is A or B, it can be said that it is excellent in practicality.
A: transparent B: pale white C: cloudiness

  As shown in Table 3, it can be seen that the solutions of Examples 1 to 23 are excellent in transparency at 60 ° C. and exhibit high viscosity despite the low concentration of the alkyl-modified PVA. Further, the solutions of Examples 4 to 7, 9 to 13, 15 and 16 in which the degree of polymerization of PVA, the structure of monomer units, the type of surfactant, and the mass ratio of surfactant to alkyl-modified PVA were specified. Was obtained with a particularly high viscosity. In Examples 3, 8 and 14, it can be seen that the transparency at 60 ° C. is lowered. This is considered due to the fact that the degree of polymerization of the alkyl-modified PVA is relatively high, the degree of saponification is relatively low, the number of carbon atoms in the alkyl group of the alkyl-modified PVA is relatively large, and the like. In Examples 20, 21 and 23, the transparency at 60 ° C. is lowered. This is considered to be caused by the difference in the structure of the surfactant or the addition amount of the surfactant being large or small, and the compatibility between the alkyl-modified PVA, the surfactant and water is slightly reduced. It is thought that this is because.

  On the other hand, when PVA does not satisfy the prescribed requirements (carbon number of alkyl group, modification rate and saponification degree) (Comparative Examples 1 to 3), when the surfactant structure does not meet the prescribed requirements (Comparative Example 4 and 5) In addition, when no surfactant was used (Comparative Example 6), it was observed that transparency at 60 ° C. was lowered, and that a high viscosity product was not obtained when the alkyl-modified PVA concentration was low.

  The alkyl-modified PVA solution of the present invention has high transparency and can increase the viscosity even when the concentration of the alkyl-modified PVA is low. Therefore, the alkyl-modified PVA solution can be suitably used for adhesives, thickeners, and the like. In addition, according to the method for producing an alkyl-modified PVA solution of the present invention, a solution having high transparency and high viscosity can be easily obtained.

Claims (8)

Containing an alkyl-modified vinyl alcohol polymer, a surfactant and water,
The alkyl-modified vinyl alcohol polymer contains a monomer unit having an alkyl group having 5 to 29 carbon atoms, the content of the monomer unit is 0.05 mol% or more and 5 mol% or less, and The saponification degree of the alkyl-modified vinyl alcohol polymer is 20 mol% or more and 99.99 mol% or less,
An alkyl-modified vinyl alcohol polymer solution in which the surfactant is a compound represented by the following formula (I).

(In Formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or carbon. An alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 2 to 30 carbon atoms , X ² is an alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 2 to 30 carbon atoms , and m is 3 or more. And a plurality of R ^{1 s} independently satisfy the above definition, provided that when R ³ is a single bond, X ¹ is not a hydrogen atom.) Said X ¹ is a hydrogen atom, Ri alkyl or alkenyl group der carbon number 2 to 29 of 1 to 29 carbon atoms, ^{X 2} is an alkyl group or an alkenyl group having a carbon number of 2 to 29 of 1 to 29 carbon atoms alkyl-modified vinyl alcohol polymer solution of claim 1 is. The alkyl-modified vinyl alcohol polymer solution according to claim 1 or 2, wherein the monomer unit is represented by the following formula (II).

(In formula (II), R ⁴ is an alkyl group having ^{5 to} 29 carbon atoms. R ⁵ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) The alkyl according to claim 3, wherein the alkyl-modified vinyl alcohol polymer is obtained by saponifying a copolymer of an unsaturated monomer represented by the following formula (III) and a vinyl ester monomer. Modified vinyl alcohol polymer solution.

(In formula (III), the definitions of R ⁴ and R ⁵ are the same as in formula (II) above.)   The alkyl-modified vinyl alcohol polymer solution according to any one of claims 1 to 4, wherein the alkyl-modified vinyl alcohol polymer has a viscosity average polymerization degree of 100 or more and 5,000 or less.   The alkyl-modified vinyl according to any one of claims 1 to 5, wherein a mass ratio of the surfactant to the alkyl-modified vinyl alcohol polymer is 0.1 / 99.9 or more and 40/60 or less. Alcohol polymer solution.   The alkyl-modified vinyl alcohol polymer solution according to any one of claims 1 to 6, wherein a concentration of the alkyl-modified vinyl alcohol polymer is 0.5% by mass or more and 50% by mass or less. A step of mixing an alkyl-modified vinyl alcohol polymer, a surfactant and water;
The alkyl-modified vinyl alcohol polymer contains a monomer unit having an alkyl group having 5 to 29 carbon atoms, the content of the monomer unit is 0.05 mol% or more and 5 mol% or less, and The saponification degree of the alkyl-modified vinyl alcohol polymer is 20 mol% or more and 99.99 mol% or less,
A method for producing an alkyl-modified vinyl alcohol polymer solution, wherein the surfactant is a compound represented by the following formula (I).

(In Formula (I), R ¹ is an alkylene group having 2 or 3 carbon atoms. R ² and R ³ are each independently a single bond or a carbonyl group. X ¹ is a hydrogen atom or carbon. An alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 2 to 30 carbon atoms , X ² is an alkyl group having 1 to 30 carbon atoms, or an alkenyl group having 2 to 30 carbon atoms , and m is 3 or more. And a plurality of R ^{1 s} independently satisfy the above definition, provided that when R ³ is a single bond, X ¹ is not a hydrogen atom.)