JP7406373B2 - Modified polyvinyl acetal resin for ceramic green sheets - Google Patents

Description

The present invention relates to a modified polyvinyl acetal resin, a polyvinyl acetal resin, and a polyvinyl acetal resin that exhibits characteristic rheological properties and has high particle dispersibility while realizing excellent thickening effects and coating properties. , relates to a polyvinyl acetal resin composition using a polyvinyl acetal resin.

Conventionally, polyvinyl acetal resins have been used for various purposes because of their excellent toughness, film-forming properties, dispersibility of inorganic powders such as pigments and organic powders, and adhesion to coated surfaces.
Specific uses of polyvinyl acetal resin are known, for example, as binders for inks and capacitors, and among them, it is often used as a material for laminated electronic components such as laminated ceramic capacitors.

Such laminated electronic components are generally manufactured through the following steps. First, a plasticizer, a dispersant, etc. are added to a solution of an organic binder resin such as polyvinyl acetal resin or poly(meth)acrylic acid ester resin dissolved in an organic solvent, and then ceramic raw material powder is added and mixed uniformly. A ceramic slurry composition having a constant viscosity is obtained after defoaming. This slurry composition is cast onto the surface of a support such as a PET film or SUS plate that has been subjected to mold release treatment. After distilling off volatile components such as a solvent by heating or the like, this is peeled off from the support to obtain a ceramic green sheet.

An electrode layer paste containing a conductive material such as palladium, silver, or nickel is printed in a predetermined pattern on the obtained ceramic green sheet. A plurality of the obtained printed ceramic green sheets are stacked one on top of the other, and a ceramic green chip is obtained through a press cutting process. Then, after a process of thermally decomposing and removing binder components, etc. contained in the obtained ceramic green chips, a so-called degreasing process is performed, and then an external electrode is formed on the end surface of the ceramic fired product obtained by firing. Through this process, laminated electronic components are manufactured.

In recent years, there has been a demand for further miniaturization and larger capacity for laminated electronic components. As multilayer ceramic capacitors become thinner, ceramic green sheets are also required to have even more layers and thinner layers, and sheet strength is required.
In order to obtain appropriate strength for ceramic green sheets, the use of a resin composition containing polyvinyl acetal resin and acrylic resin as a binder has been considered. For example, Patent Document 1 describes a modified polyvinyl acetal resin that has excellent compatibility with acrylic resins. Further, Patent Document 2 describes an inorganic fine particle dispersion containing at least one selected from the group consisting of ethyl cellulose, (meth)acrylic resin, and polyvinyl acetal resin, a specific organic compound, inorganic fine particles, and an organic solvent. A paste is described, and it is described that a sintered layer with excellent surface smoothness can be formed.

On the other hand, inorganic fine particle dispersed pastes are required to have viscosity and thixotropy suitable for screen printing. Furthermore, in inorganic fine particle dispersion pastes, it is necessary to consider the dispersibility of inorganic fine particles in addition to viscosity characteristics, but at present, a binder resin that satisfies all of these requirements has not been put into practical use.

Japanese Patent Application Publication No. 2012-241043 International Publication No. 2011/016442

The present invention relates to a modified polyvinyl acetal resin, a polyvinyl acetal resin, and a polyvinyl acetal resin that exhibits characteristic rheological properties and has high particle dispersibility while realizing excellent thickening effects and coating properties. , an object of the present invention is to provide a polyvinyl acetal resin composition using a polyvinyl acetal resin.

The present invention is a modified polyvinyl acetal resin characterized by containing a structural unit having an alkyl modifying group having 4 or more carbon atoms in its side chain.
The present invention will be explained in detail below.

As a result of intensive studies, the present inventors have found that modified polyvinyl acetal resins containing structural units having an alkyl modifying group having 4 or more carbon atoms in their side chains exhibit characteristic rheological properties, have excellent thickening effects and The present inventors have discovered that they have high particle dispersibility while achieving workability, etc., and have completed the present invention. Note that in the present invention, the side chain refers to a molecular chain branching from the main chain. Therefore, cases where an alkyl modifying group is incorporated into the main chain itself are not included in the present invention.

The modified polyvinyl acetal resin of the present invention contains a structural unit having an alkyl modifying group having 4 or more carbon atoms in a side chain. By having an alkyl modified group in the side chain, characteristic rheological properties can be expressed and an excellent thickening effect can be obtained. Further, by having 4 or more carbon atoms, remarkable thickening properties and thixotropy can be imparted.
In addition, the said alkyl modification group may consist of one type of alkyl modification group, and may consist of two or more types of alkyl modification groups.

The structural unit having an alkyl modified group having 4 or more carbon atoms in its side chain is preferably a structural unit represented by the following formula (1) (hereinafter, such a structural unit will be referred to as a long chain alkyl modified bonding unit). ).
Having the structural unit represented by the following formula (1) has the advantage of exhibiting characteristic rheological properties and obtaining an excellent thickening effect. In particular, when the shear rate is low, the viscosity can be high. In addition, it is possible to reduce the amount of decrease in viscosity when the shear rate is increased (the viscosity ratio is low).

式（１）中、Ｒ^１は炭素数４～２５のアルキル基、Ｒ^２は単結合、Ｏ、ＣＯＯ、又は、ＣＯＮＨを表す。

In formula (1), R ¹ represents an alkyl group having 4 to 25 carbon atoms, and R ² represents a single bond, O, COO, or CONH.

The above R ¹ is an alkyl group having 4 to 25 carbon atoms. When the carbon number of R ¹ is within the above range, when it is made into an aqueous solution, it is possible to obtain excellent thickening effect, coatability, and particle dispersibility while maintaining the properties. The number of carbon atoms is preferably 8 to 20. Further, R ¹ may be a combination of two or more alkyl groups having different numbers of carbon atoms.
Note that R ¹ above corresponds to an alkyl modified group.

Examples of the alkyl group having 4 to 25 carbon atoms include butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, and nonyl group. , decyl group, etc.

The alkyl group having 4 to 25 carbon atoms may be linear or branched.
Examples of the linear alkyl group include n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group. , n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, n-eicosyl group, n-docosyl group and the like.

Examples of the branched alkyl group include isobutyl group, s-butyl group, t-butyl group, isopentyl group, neopentyl group, 1-methylhexyl group, 1-methylheptyl group, 1-methyloctyl group, -methylnonyl group, 1-methyldecyl group, 1-methylundecyl group, 1-methyldodecyl group and the like. Also, 1-methyltridecyl group, 1-methyltetradecyl group, 1-methylheptadecyl group, 1-methylhexadecyl group, 1-methylpentadecyl group, 1-methyloctadecyl group, 1-methyleicosyl group, etc. can be mentioned.
Furthermore, an alkyl group in which the 1st carbon atom is substituted with an alkyl group having 2 or more carbon atoms (for example, 1-ethyldecyl group, 1-propylnonyl group, 1-butyloctyl group, 1-pentylheptyl group, 1-octyldecyl group, etc.).
Furthermore, in the branched alkyl group, the branching position is not limited to the 1st-position carbon atom, but may be at the 2nd-position or higher carbon atom. For example, examples of the alkyl group in which a methyl group is substituted at the 2nd or higher carbon atom include 2-methylundecyl, 3-methylundecyl, and 4-methylundecyl. In addition, examples of alkyl groups in which an alkyl group having 2 or more carbon atoms is substituted at the 2nd or higher carbon atom include 2-ethylhexyl group, 2-ethylheptyl group, 2-ethyloctyl group, 2-ethyl Examples include undecyl group, 2-ethyl octadecyl group, 2-propyl undecyl group, 2-butyl undecyl group, and 2-octyl undecyl group. Further examples include 3-ethyl undecyl group, 4-ethyl octadecyl group, 4-butyl octadecyl group, neodecyl group, and the like.

In the present invention, the alkyl modified group (R ¹ ) is preferably a branched alkyl group. Further, the alkyl modified group may be composed of two or more types of alkyl groups including a branched alkyl group, or may be composed only of a branched alkyl group.
When the alkyl modifying group is composed of two or more types of alkyl groups including a branched alkyl group, the ratio of the branched alkyl group is 40 to 100% of the total amount of modified groups. It is preferable.
Furthermore, when the alkyl modified group is composed of a linear alkyl group and a branched alkyl group, the ratio between the two (linear alkyl group: branched alkyl group) is 50. :50 to 20:80 is preferable.

In the present invention, the structural unit having an alkyl modifying group having 4 or more carbon atoms in its side chain preferably has a structure in which the alkyl modifying group having 4 or more carbon atoms is bonded via an acetal bond (hereinafter, such a structural unit (The structural unit is also called a long-chain alkyl-modified acetal unit).
Thereby, characteristic rheological properties can be expressed and an excellent thickening effect can be obtained.
In particular, when the shear rate is low, the viscosity can be relatively low. Furthermore, when the shear rate is increased, the amount of decrease in viscosity can be increased (the viscosity ratio is high).
The structural unit having an alkyl modifying group having 4 or more carbon atoms in its side chain is preferably a structural unit represented by the following formula (2).

式（２）中、Ｒ^３は炭素数４～２５のアルキル基を表す。

In formula (2), R ³ represents an alkyl group having 4 to 25 carbon atoms.

As the alkyl group having 4 to 25 carbon atoms, those similar to those mentioned above can be used. Among these, the number of carbon atoms is preferably 6 to 20, particularly n-hexyl group, n-nonyl group, n-undecyl group, n-pentadecyl group, 1-methyloctyl group, 1-methyldecyl group, 2 -Ethylhexyl group, 2-ethylheptyl group, 1-butyloctyl group, neodecyl group, etc. are preferred.

In the modified polyvinyl acetal resin of the present invention, the preferable lower limit of the content of the structural unit having an alkyl-modifying group in the side chain (the amount of alkyl-modifying units) is 0.1 mol%, and the preferable upper limit is 5 mol%. By setting the amount of alkyl modification units to 0.1 mol % or more, excellent thickening effect, coatability, and particle dispersibility can be obtained. By controlling the amount of alkyl modification units to 5 mol % or less, the properties can be stabilized when an aqueous solution is prepared. A more preferable lower limit of the above content is 0.5 mol%, and a more preferable upper limit is 3 mol%.

When the modified polyvinyl acetal resin of the present invention includes a structure in which alkyl modifying groups having 4 or more carbon atoms are bonded via an acetal bond (long chain alkyl modified acetal unit), the content of the long chain alkyl modified acetal unit is A more preferable lower limit is 0.5 mol%, and a more preferable upper limit is 4.5 mol%. Further, a more preferable upper limit is 4 mol%, and an even more preferable upper limit is 3.5 mol%.
In particular, when the long-chain alkyl-modified acetal unit with 4 to 6 carbon atoms is included, it is preferably 0.5 to 5 mol%, and when the long-chain alkyl-modified acetal unit with 7 to 10 carbon atoms is included, it is 0. The amount is preferably from .1 to 4.5 mol%, and when the long-chain alkyl-modified acetal unit having 11 to 18 carbon atoms is included, the amount is preferably from 0.1 to 4 mol%. Further, when the long-chain alkyl-modified acetal unit having 19 to 25 carbon atoms is included, it is preferably 0.1 to 3.5 mol%.

When the modified polyvinyl acetal resin of the present invention contains a long-chain alkyl-modified acetal unit, the square of the number of carbon atoms (X) of the alkyl group in the long-chain alkyl-modified acetal unit and the content of the long-chain alkyl-modified acetal unit ( The product (X ² ×Y) with Y) is preferably 15 to 650. Further, it is more preferably 50 to 500, and even more preferably 100 to 400.
Further, when the modified polyvinyl acetal resin of the present invention does not contain a long-chain alkyl-modified bonding unit but contains a long-chain alkyl-modified acetal unit, the above-mentioned X ² ×Y is preferably from 50 to 650. Further, it is more preferably from 100 to 500, and even more preferably from 150 to 450.
Further, when the modified polyvinyl acetal resin of the present invention contains both a long-chain alkyl-modified bonding unit and a long-chain alkyl-modified acetal unit, the above-mentioned X ² ×Y is preferably from 15 to 600. Further, it is more preferably 50 to 450, and even more preferably 100 to 400.

The modified polyvinyl acetal resin of the present invention has a constituent unit having a hydroxyl group, a constituent unit having an acetyl group, and a constituent unit having an acetal group.

The modified polyvinyl acetal resin of the present invention has the above-mentioned hydroxyl group-containing structural unit.
The preferable lower limit of the content of the structural unit having a hydroxyl group (hydroxyl group amount) in the modified polyvinyl acetal resin of the present invention is 40 mol%, and the preferable upper limit is 99 mol%. By setting the amount of hydroxyl groups to 40 mol% or more, water solubility can be maintained, and by setting the amount to 99 mol% or less, storage stability can be maintained.
A more preferable lower limit of the amount of hydroxyl groups is 80 mol%, and a more preferable upper limit is 98 mol%.

The modified polyvinyl acetal resin of the present invention has a structural unit having the above acetyl group.
The preferable lower limit of the content of the structural unit having an acetyl group (acetyl group amount) in the modified polyvinyl acetal resin of the present invention is 0.1 mol%, and the preferable upper limit is 20 mol%. By setting the amount of acetyl groups to 0.1 mol% or more, storage stability can be maintained, and by setting the amount of acetyl groups to 20 mol% or less, storage stability can be maintained. A more preferable lower limit of the amount of acetyl groups is 0.3 mol%, and a more preferable upper limit is 10 mol%.

The polyvinyl acetal resin has a structural unit having the acetal group.
The content of the structural unit having the acetal group (degree of acetalization) in the polyvinyl acetal resin is preferably 0.1 mol% or more and 40 mol% or less. By setting the degree of acetalization to 0.1 mol% or more, storage stability and flexibility can be improved. Water solubility can be maintained by controlling the degree of acetalization to 40 mol% or less. More preferably, it is 2 to 20 mol%.
In this specification, the degree of acetalization refers to the number of hydroxyl groups in polyvinyl alcohol that has been acetalized with an aldehyde (butyraldehyde, acetaldehyde, etc.) having 3 or less carbon atoms in the portion excluding the aldehyde group. It is a ratio. Therefore, the content of the above-mentioned "structure in which alkyl modifying groups having 4 or more carbon atoms are bonded via an acetal bond" is not included in the degree of acetalization.
In addition, as a method for calculating the degree of acetalization, since the acetal group of polyvinyl acetal resin is formed by acetalization from two hydroxyl groups, a method of counting the two acetalized hydroxyl groups is adopted, and the acetalization degree is calculated by counting the two hydroxyl groups that have been acetalized. Calculate the mol% of the degree of oxidation.

The content of acetoacetal groups acetalized with acetaldehyde in the modified polyvinyl acetal resin of the present invention is preferably 0.1 mol% or more and less than 40 mol%. By keeping it within the above range, water solubility can be maintained and excellent viscosity characteristics can be obtained.
Further, the content of butyl acetal groups acetalized with butyraldehyde in the modified polyvinyl acetal resin of the present invention is preferably 0.1 mol% or more and less than 25 mol%. By keeping it within the above range, water solubility can be maintained and excellent viscosity characteristics can be obtained.
When the modified polyvinyl acetal resin of the present invention contains both a structural unit having an acetal group (having 3 or less carbon atoms) and a long-chain alkyl-modified acetal unit, the long-chain alkyl-modified acetal unit corresponds to the structural unit having an acetal group. The ratio [amount of structural units having an acetal group/amount of long-chain alkyl-modified acetal units] is preferably 200 or less. Moreover, it is more preferable that the said ratio is 70 or less, and it is still more preferable that it is 25 or less. Note that the lower limit is not particularly limited, but is preferably 0.01.

The total amount of the degree of acetalization and the amount of alkyl modification units [degree of acetalization+amount of alkyl modification units] in the modified polyvinyl acetal resin of the present invention is preferably 0.2 to 50. By setting it within the above range, water solubility can be maintained and excellent viscosity characteristics can be obtained.
The above degree of acetalization + amount of alkyl modification units is more preferably from 1.5 to 25.

The ratio of the degree of acetalization to the amount of alkyl modification units in the modified polyvinyl acetal resin of the present invention [degree of acetalization/amount of alkyl modification units] is preferably from 1 to 100. By setting it within the above range, water solubility can be maintained and excellent viscosity characteristics can be obtained.
The degree of acetalization/amount of alkyl modification units is more preferably from 2.5 to 20.

The preferred lower limit of the degree of polymerization of the modified polyvinyl acetal resin of the present invention is 500, and the preferred upper limit is 4,500. Industrial production becomes easy because the degree of polymerization is 500 or more. When the degree of polymerization is 4,500 or less, the solution viscosity becomes appropriate and industrial production becomes possible. A more preferable lower limit of the degree of polymerization is 1,000, and a more preferable upper limit is 2,500.

The modified polyvinyl acetal resin of the present invention may contain both a long-chain alkyl-modified bonding unit and a long-chain alkyl-modified acetal unit. In this case, the content ratio of long-chain alkyl-modified bonding units to long-chain alkyl-modified acetal units (long-chain alkyl-modified bonding units/long-chain alkyl-modified acetal units) is preferably from 0.1 to 10.

The method for producing the modified polyvinyl acetal resin of the present invention includes a method of preparing polyvinyl alcohol containing a constitutional unit having an alkyl modifying group in its side chain and then acetalizing it; Examples include a method of acetalizing unused polyvinyl alcohol and then adding an alkyl modified group thereto.
More specifically, polyvinyl alcohol having a structural unit represented by the above formula (1) is prepared in advance and then acetalized, and polyvinyl alcohol not having a structural unit represented by the above formula (1) is acetalized. Examples include a method of adding moieties corresponding to R ¹ and R ² of the structural unit represented by the above formula (1) after converting the compound into a compound.

As a method for producing polyvinyl alcohol containing a constitutional unit having an alkyl-modified group in the side chain, for example, after copolymerizing a vinyl alkyl ether such as vinyl dodecyl ether with vinyl acetate, the alcohol of the obtained copolymer is Examples include a method of saponifying a solution by adding an acid or an alkali to it. Alternatively, polyvinyl alcohol containing a structural unit having an alkyl modifying group in the side chain may be produced by a method of adding an alkyl modifying group.
Further, examples of the method for adding the alkyl modified group include graft polymerization.

Examples of the method for producing polyvinyl alcohol containing a structural unit having an alkyl modifying group in the side chain by the method of adding an alkyl modifying group include the following method.
For example, a method for obtaining polyvinyl alcohol (graft copolymer) containing a structural unit having an alkyl modified group by adding polyvinyl alcohol and an acrylic acrylate such as dodecyl acrylate to ethyl acetate and graft polymerizing the mixture can be mentioned.

Examples of the method for producing the modified polyvinyl acetal resin containing the long-chain alkyl-modified acetal unit having 4 or more carbon atoms include a method of acetalizing unmodified polyvinyl alcohol using an aldehyde having 5 or more carbon atoms. In particular, when producing a modified polyvinyl acetal resin containing the long-chain alkyl modified acetal unit having 4 or more carbon atoms, it is preferable to carry out acetalization at a temperature of 60 to 70°C and for a period of 6 to 7 hours. .

Polyvinyl alcohol (hereinafter also simply referred to as polyvinyl alcohol) that does not contain a constitutional unit having an alkyl-modified group in its side chain can be obtained, for example, by saponifying a copolymer of vinyl ester and ethylene. Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and the like. Among them, vinyl acetate is preferred from the viewpoint of economy.

The modified polyvinyl acetal resin of the present invention may be one obtained by copolymerizing an ethylenically unsaturated monomer to the extent that the effects of the present invention are not impaired. The ethylenically unsaturated monomer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, phthalic acid (anhydride), maleic acid (anhydride), and itaconic acid (anhydride). Further examples include acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride, acrylamide-2-methylpropanesulfonic acid and its sodium salt. Further examples include ethyl vinyl ether, butyl vinyl ether, N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinylsulfonate, sodium allylsulfonate, and the like. Additionally, terminal-modified polyvinyl alcohol obtained by copolymerizing ethylene with a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid and saponifying the copolymerization may also be used. I can do it.

Another aspect of the polyvinyl acetal resin of the present invention is that in an aqueous solution with a solid content concentration of 5% by weight, the ratio of the maximum value to the minimum value of viscosity in the shear rate region of 1 to 100 [1/s] at a temperature of 25°C is 1. .5 to 150. By setting it as such a range, sufficient rheology and viscosity improvement effects can be obtained. The preferable lower limit is 3, the preferable upper limit is 100, the more preferable lower limit is 10, and the more preferable upper limit is 120.
Further, the polyvinyl acetal resin of another embodiment preferably has a maximum value in a shear rate range of 1 to 100 [1/s] at a temperature of 25°C.
In addition, as a composition of the polyvinyl acetal resin of another aspect, the same composition as the modified polyvinyl acetal resin of this invention can be used.

A polyvinyl acetal resin composition containing the modified polyvinyl acetal resin of the present invention or a polyvinyl acetal resin of another embodiment is also one of the present invention.

The content of the modified polyvinyl acetal resin of the present invention or the polyvinyl acetal resin of another embodiment in the polyvinyl acetal resin composition of the present invention is not particularly limited, but the preferred lower limit is 0.5% by weight, and the preferred upper limit is 20% by weight. %. By setting the content of polyvinyl acetal resin to 0.5% by weight or more, the thickening effect due to the interaction between the resins will be sufficient, and by setting the content to 20% by weight or less, a resin with good handling properties can be obtained. be able to. More preferably, it is 1 to 15% by weight.

The polyvinyl acetal resin composition of the present invention contains a solvent.
The above-mentioned solvent is not particularly limited as long as it can dissolve the polyvinyl acetal resin, and examples thereof include water, isopropyl alcohol, methanol, ethanol, and the like.
The above solvents may be used alone or in combination of two or more.
The content of the solvent in the polyvinyl acetal resin composition of the present invention is not particularly limited, but the preferable lower limit is 1% by weight, and the preferable upper limit is 99.5% by weight.

In addition to the above-mentioned polyvinyl acetal resin and solvent, the polyvinyl acetal resin composition of the present invention may optionally contain flame retardant aids, thickeners, antifoaming agents, leveling agents, and adhesion imparting agents. Additives may also be added.

The use of the polyvinyl acetal resin composition of the present invention is not particularly limited. By applying it on a peelable support and drying it, a ceramic green sheet with excellent mechanical strength and flexibility can be obtained.
It can also be used as a binder for ink products such as gel ink, and as a raw material for adhesives, paints, films, and the like.
By using the polyvinyl acetal resin composition of the present invention, water can be used as a solvent instead of an organic solvent, which is preferable from the viewpoint of environmental pollution, toxicity, danger of explosion, etc.

According to the present invention, a modified polyvinyl acetal resin, a polyvinyl acetal resin, and a polyvinyl acetal resin that exhibit characteristic rheological properties and have high particle dispersibility while realizing excellent thickening effects, coating properties, film properties, etc. A polyvinyl acetal resin composition using the modified polyvinyl acetal resin and the polyvinyl acetal resin can be provided.
In particular, the modified polyvinyl acetal resin of the present invention maintains a suitable viscosity range even when external forces such as shearing are applied, after a long period of time, when the temperature changes, and when solution characteristics such as pH are changed. It becomes possible to maintain Furthermore, since it has excellent thread breakability, it can be suitably used in coating liquids and the like.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Synthesis of polyvinyl alcohol (a))
Into a flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, 1000 parts by weight of vinyl acetate, 80 parts by weight of dodecyl vinyl ether, 160 parts by weight of 1-ethyldecyl vinyl ether, and 300 parts by weight of methanol were added. After nitrogen substitution, the temperature was raised to 60°C. 1.1 parts by weight of 2,2-azobisisobutyronitrile was added to this system to initiate polymerization. Polymerization was stopped 5 hours after the start of polymerization. The solid content concentration in the system at the time of termination of polymerization was 53% by weight, and the polymerization yield based on all monomers was 65% by weight. After removing unreacted monomers under reduced pressure, a 45% by weight methanol solution of the copolymer was obtained. It was confirmed by quantitative determination of unreacted monomers that the obtained copolymer contained 98.6 mol% of vinyl acetate units, 0.4 mol% of vinyl dodecyl ether units, and 1.0 mol% of 1-ethyldecyl vinyl ether units. It was done.

While stirring 100 parts by weight of a methanol solution of this copolymer at 40° C., 25 parts by weight of a 3% NaOH methanol solution was added thereto, and after thorough mixing, the mixture was allowed to stand. After 30 minutes, the solidified polymer was pulverized using a pulverizer, washed with methanol, and dried to obtain a polymer powder (hereinafter referred to as polyvinyl alcohol (a)).
The degree of saponification of polyvinyl alcohol (a) was 99.5 mol%, the amount of alkyl modification units was 1.4 mol%, and the degree of polymerization was 1500.

(Example 1)
80 g of polyvinyl alcohol (a) was added to 1400 g of pure water and stirred at a temperature of 90° C. for about 2 hours to dissolve. This solution was cooled to 40°C, and 20g of hydrochloric acid with a concentration of 35% by weight and 5g of n-butyraldehyde were added thereto, and then the acetalization reaction was carried out while maintaining the liquid temperature at 40°C. Thereafter, the reaction was completed by maintaining the liquid temperature at 40°C for 3 hours, and neutralized by adding 15g of a 20% by weight diluted aqueous sodium hydroxide solution. % by weight) was obtained.
The obtained modified polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetalization, and the amount of alkyl modification units were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). was measured. As a result, the amount of hydroxyl groups was 92.7 mol%, the amount of acetyl groups was 0.8 mol%, the total degree of acetalization (degree of butyralization) was 5.1 mol%, and the amount of alkyl modification units (modification group content) was 1. It was .4 mol%.
The structural unit having an alkyl modified group is a structural unit represented by the above formula (1), and has a structure (R ¹ =C ₁₂ H ₂₅ , R ² =O) represented by the above formula (1). there were. Furthermore, R ¹ consisted of a linear alkyl (n-dodecyl group) and a branched alkyl (1-ethyldecyl group), and the ratio of the linear alkyl to the branched alkyl was 3:7. .

(Example 2)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 3 g of acetaldehyde was added instead of n-butyraldehyde. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units (modification group content) was measured. The results are shown in Table 1.

(Example 3)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 6.1 g of acetaldehyde was added instead of n-butyraldehyde. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 4)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 3 g of n-butyraldehyde was added. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 5)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 10 g of acetaldehyde was added instead of n-butyraldehyde. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 6)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 12 g of acetaldehyde was added instead of n-butyraldehyde. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 7)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that 22 g of acetaldehyde was added instead of n-butyraldehyde. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 8)
Alkyl-modified polyvinyl was produced in the same manner as in Example 3, except that PVA with a degree of saponification of 87.4 mol%, an amount of alkyl-modified units of 1.4 mol%, and a degree of polymerization of 1500 was used in place of polyvinyl alcohol (a). An acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 9)
Alkyl modification was carried out in the same manner as in Example 3, except that PVA with a saponification degree of 99.5 mol%, an alkyl modification unit amount of 1.4 mol%, and a polymerization degree of 500 was used in place of polyvinyl alcohol (a). A polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 10)
Alkyl-modified polyvinyl was produced in the same manner as in Example 3, except that PVA with a degree of saponification of 99.5 mol%, an amount of alkyl-modified units of 1.4 mol%, and a degree of polymerization of 3000 was used in place of polyvinyl alcohol (a). An acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 11)
Alkyl-modified polyvinyl was produced in the same manner as in Example 3, except that PVA with a degree of saponification of 99.5 mol%, an amount of alkyl-modified units of 0.1 mol%, and a degree of polymerization of 1500 was used in place of polyvinyl alcohol (a). An acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 12)
Alkyl-modified polyvinyl was produced in the same manner as in Example 3, except that PVA with a degree of saponification of 99.5 mol%, an amount of alkyl-modified units of 4.8 mol%, and a degree of polymerization of 1500 was used in place of polyvinyl alcohol (a). An acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1.

(Example 13)
The same method as in Example 3 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₈ H ₁₇ , C ₁₂ H ₂₅ , R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that ^R1 consisted of a linear alkyl (n-octyl group) and a branched alkyl (1-ethyldecyl group), and the ratio of the linear alkyl to the branched alkyl was 25:75. .

(Example 14)
The same method as in Example 3 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₁₈ H ₃₇ , C ₁₂ H _{25 ,} R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that ^R1 consisted of a linear alkyl (n-octadecyl group) and a branched alkyl (1-ethyldecyl group), and the ratio of linear alkyl to branched alkyl was 25:75. .

(Example 15)
The same method as in Example 3 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₁₂ H ₂₅ , C ₄ H _{9 ,} R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that ^R1 consisted of a linear alkyl (n-dodecyl group) and a branched alkyl (t-butyl group), and the ratio of linear alkyl to branched alkyl was 29:71. .

(Example 16)
The same method as in Example 3 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₁₂ H ₂₅ , C ₁₈ H _37, R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consists of a linear alkyl (n-dodecyl group) and a branched alkyl (1-octyldecyl group), and the ratio of the linear alkyl to the branched alkyl is 28:72. Ta.

(Example 17)
An alkyl-modified polyvinyl acetal resin was prepared in the same manner as in Example 3, except that PVA in which the alkyl-modified group was changed to (R ¹ =C ₁₂ H ₂₅ , R ² =O) was used in place of polyvinyl alcohol (a). A solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consisted only of branched alkyl (1-ethyldecyl group), and the proportion of linear alkyl was 0%.

(Example 18)
An alkyl-modified polyvinyl acetal resin was prepared in the same manner as in Example 3, except that PVA in which the alkyl-modified group was changed to (R ¹ =C ₁₂ H ₂₅ , R ² =O) was used in place of polyvinyl alcohol (a). A solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consisted only of linear alkyl (n-dodecyl group), and the proportion of branched alkyl was 0%.

(Example 19)
An alkyl-modified polyvinyl acetal resin was prepared in the same manner as in Example 3, except that PVA in which the alkyl-modified group was changed to (R ¹ =C ₈ H ₁₇ , R ² =O) was used in place of polyvinyl alcohol (a). A solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consisted only of linear alkyl (octyl group), and the proportion of branched alkyl was 0%.

(Example 20)
An alkyl-modified polyvinyl acetal resin was prepared in the same manner as in Example 3, except that PVA in which the alkyl-modified group was changed to (R ¹ =C ₁₈ H ₃₇ , R ² =O) was used in place of polyvinyl alcohol (a). A solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consisted only of linear alkyl (octadecyl group), and the proportion of branched alkyl was 0%.

(Example 21)
The same method as in Example 1 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₂₄ H ₄₉ , C ₁₂ H ₂₅ , R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consists of a linear alkyl (C ₂₄ H ₄₉ group) and a branched alkyl (1-ethyldecyl group), and the ratio of the linear alkyl to the branched alkyl is 30:70. Ta.

(Example 22)
The same method as in Example 3 was used, except that instead of polyvinyl alcohol (a), PVA in which the alkyl modified group was changed to (R ¹ =C ₂₄ H ₄₉ , C ₁₂ H ₂₅ , R ² =O) was used. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that R ¹ consists of a linear alkyl (C ₂₄ H ₄₉ group) and a branched alkyl (1-ethyldecyl group), and the ratio of the linear alkyl to the branched alkyl is 30:70. Ta.

(Example 23)
Alkyl was prepared in the same manner as in Example 3, except that PVA with an alkyl modified group (R ¹ = C ₈ H ₁₇ , R ² = O) and a polymerization degree of 3000 was used in place of polyvinyl alcohol (a). A modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of alkyl modification units was measured. The results are shown in Table 1. Note that ^R1 consisted of a linear alkyl (n-octyl group) and a branched alkyl (1-ethylhexyl group), and the ratio of the linear alkyl to the branched alkyl was 30:70. .

(Example 24)
The same procedure as in Example 1 was carried out, except that 2 g of n-butyraldehyde and 1.5 g of decylaldehyde were added instead of 5 g of n-butyraldehyde, and the liquid temperature was maintained at 60°C for 6 hours to perform acetalization. An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained by the method. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of desyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 25)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight). The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of desyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 26)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight). The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of heptyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 27)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5 % by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of heptyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 28)
An alkyl-modified polyvinyl acetal resin solution (resin content :5% by weight). The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of desyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 29)
An alkyl-modified polyvinyl acetal resin solution (resin content: 5% by weight) was prepared in the same manner as in Example 24, except that 1.3 g of decyl aldehyde was added instead of 2 g of n-butyraldehyde and 1.5 g of decyl aldehyde. Obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and the amount of hydroxyl groups, the amount of acetyl groups, the degree of butyralization, the degree of desyralization, and the alkyl group were determined using ¹ H-NMR (nuclear magnetic resonance spectrum). The amount of modification units (total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 30)
In place of polyvinyl alcohol (a), unmodified PVA (degree of saponification 99.1 mol%, degree of polymerization 1500) was used, and in place of 2 g of n-butyraldehyde and 1.5 g of decyl aldehyde, 3 g of decyl aldehyde was added. Except for this, a polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 24. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and ^the amount of hydroxyl groups, the amount of acetyl groups, the degree of desyralization, and the amount of alkyl modification units ( The total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 31)
In place of polyvinyl alcohol (a), unmodified PVA (degree of saponification 99.1 mol%, degree of polymerization 1500) was used, and in place of 2 g of n-butyraldehyde and 1.5 g of decyl aldehyde, 6 g of decyl aldehyde was added. Except for this, a polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 24. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and ^the amount of hydroxyl groups, the amount of acetyl groups, the degree of desyralization, and the amount of alkyl modification units ( The total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 32)
In place of polyvinyl alcohol (a), unmodified PVA (degree of saponification 99.1 mol%, degree of polymerization 1500) was used, and in place of 2 g of n-butyraldehyde and 1.5 g of decyl aldehyde, 7 g of decyl aldehyde was added. Except for this, a polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 24. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and ^the amount of hydroxyl groups, the amount of acetyl groups, the degree of desyralization, and the amount of alkyl modification units ( The total alkyl modification group content) was measured. The results are shown in Table 1.

(Example 33)
In place of polyvinyl alcohol (a), unmodified PVA (degree of saponification 99.1 mol%, degree of polymerization 1500) was used, and in place of 2 g of n-butyraldehyde and 1.5 g of decyl aldehyde, 1.5 g of n-butyraldehyde was used. A polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 24, except that 2g and 6g of decylaldehyde were added. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and ^the amount of hydroxyl groups, the amount of acetyl groups, the degree of desyralization, and the amount of alkyl modification units ( The total alkyl modification group content) was measured. The results are shown in Table 1.

(Comparative example 1)
Instead of polyvinyl alcohol (a), PVA having a carboxylic acid modification unit shown in formula (3) (carboxylic acid modification unit amount 1.4 mol%, saponification degree 97.4 mol%, polymerization degree 1500) was used. Except for this, a carboxylic acid-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units (modification group content) was measured. The results are shown in Table 1.

(Comparative example 2)
Instead of polyvinyl alcohol (a), PVA having a sulfonic acid modification unit shown in formula (4) (sulfonic acid modification unit amount 2.4 mol%, saponification degree 98.4 mol%, polymerization degree 1500) was used. Except for this, a sulfonic acid-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative example 3)
Instead of polyvinyl alcohol (a), PVA whose modifying group species is ethylene oxide (R ¹ = [CH ₂ CH ₂ O] _n -H, R ² = O, amount of ethylene oxide modifying units 4.0 mol%, saponification) An ethylene oxide-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that ethylene oxide-modified polyvinyl acetal resin solution (resin content: 5% by weight) was used. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative example 4)
A polyvinyl acetal resin solution (resin content: 5 % by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative example 5)
A polyvinyl acetal resin solution (resin content: 5 % by weight) was obtained. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative example 6)
Instead of polyvinyl alcohol (a), PVA whose modifying group species is an amine (R ¹ = NH ₂ , R ² = single bond, amine modification unit amount 2.9 mol%, degree of saponification 96.5 mol%, polymerization An amine-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that a polyvinyl acetal resin solution (resin content: 5% by weight) was used. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative Example 7)
Instead of polyvinyl alcohol (a), PVA whose modified group species is amide (R ¹ =CONH ₂ , R ² = single bond, amide modification unit amount 2.6 mol%, saponification degree 97.5 mol%, polymerization An amine-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that a polyvinyl acetal resin solution (resin content: 5% by weight) was used. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

(Comparative example 8)
Instead of polyvinyl alcohol (a), PVA having a pyrrolidone modification unit shown in formula (4) (vinyl pyrrolidone unit, amount of pyrrolidone modification unit 2.4 mol%, degree of saponification 97.6 mol%, degree of polymerization 1500) was used. A pyrrolidone-modified polyvinyl acetal resin solution (resin content: 5% by weight) was obtained in the same manner as in Example 1, except that the resin solution was used. The obtained polyvinyl acetal resin was dissolved in DMSO-d ₆ (dimethyl sulfoxide), and using ¹ H-NMR (nuclear magnetic resonance spectrum), the amount of hydroxyl groups, the amount of acetyl groups, the degree of acetoacetalization, the degree of butyralization, and The amount of modification units was measured. The results are shown in Table 1.

<Evaluation>
The following evaluations were performed on the (modified) polyvinyl acetal resin solutions obtained in Examples and Comparative Examples. The results are shown in Table 1.

(1) Using a viscosity rotational rheometer (manufactured by Thermo Fisher Scientific; HAAKE Rheo Stress 3000), measure the viscosity at a shear rate of 1 [1/s] in the CR rotation time dependent measurement mode under the following measurement conditions. did.
<Measurement conditions>
Rotating disk: flat plate Diameter of rotating disk: 35mm
Gap: 0.5mm

(2) Viscosity ratio (ratio of maximum and minimum viscosity values in the shear rate range of 1 to 100 [1/s] at a temperature of 25°C)
Using a rotational rheometer (manufactured by Thermo Fisher Scientific; HAAKE Rheo Stress 3000), the shear rate was continuously maintained at a constant speed from 0.01 to 100 [1/s] in CR flow curve mode under the following measurement conditions. The viscosity was measured when the viscosity was changed, and the maximum/minimum values were determined.
<Measurement conditions>
Rotating disk: flat plate Diameter of rotating disk: 35mm
Gap: 0.5mm
Speed of changing shear rate: 0.83 [1/s ² ]

(3) Dispersibility To 100 parts by weight of the polyvinyl acetal resin solutions obtained in Examples and Comparative Examples, 10 parts by weight of pigment (carbon black) and 95 parts by weight of water were added. Next, a water-based ink was prepared by dispersing the mixture in a ball mill for 4 hours. Then, put it in a settling tube and visually check the dispersion state of the pigment after one week (temperature 20 ± 5 ° C, humidity 45-55%). If no precipitation has occurred, ○, if precipitation has occurred. was marked as ×.

(4) Viscosity stability over time After storing the polyvinyl acetal resin solutions obtained in Examples and Comparative Examples for 30 days at a temperature of 20 ± 5°C and a humidity of 45 to 55%, the viscosity change was compared to the viscosity before storage. The case where it was less than 10% was rated ○, and the case where it was 10% or more was rated x.

(5) Using a thread-breakable capillary breakup rheometer (manufactured by Thermo Fisher Scientific; HAAKE CaBER1), the polyvinyl acetal resin solutions obtained in Examples and Comparative Examples were subjected to elongation shear at a speed of 5 cm/s. When the threads (liquid column) of the resin solution were broken when the resin solution was applied, it was marked as ○, and when it was not broken, it was marked as ×.

(6) pH resistance Regarding the polyvinyl acetal resin solutions obtained in Examples and Comparative Examples, measurements of "(1) viscosity" and "(2) viscosity ratio" were made when the pH was adjusted to 5 ± 0.1. Also, the pH was adjusted to 9±0.1. ○ if the measured viscosity and viscosity ratio change rate ([measured value at pH 9 ± 0.1 / measured value at pH 5 ± 0.1] × 100) is less than 10%; ○ if it is 10 to 20%. △, cases larger than 20% were marked as ×.
Note that when the measurement result of "(2) Viscosity ratio" was "1.0", the rate of change in the viscosity ratio was not measured.

(7) Temperature Resistance "(1) Viscosity" and "(2) Viscosity Ratio" after storing the polyvinyl acetal resin solutions obtained in Examples and Comparative Examples at a temperature of 50±1°C and a humidity of 50±1°C for one week. ” were measured. ○ if the measured viscosity and viscosity ratio change rate ([measured value after storage / measured value before storage] x 100) is less than 10%, △ if it is 10 to 20%, greater than 20% The case was marked as ×.
Note that when the measurement result of "(2) Viscosity ratio" was "1.0", the rate of change in the viscosity ratio was not measured.

According to the present invention, a modified polyvinyl acetal resin, a polyvinyl acetal resin, and a polyvinyl acetal resin, which exhibit characteristic rheological properties, achieve excellent thickening effects, coating properties, etc., and have high particle dispersibility. It is possible to provide an acetal resin and a polyvinyl acetal resin composition using a polyvinyl acetal resin.

Claims (10)

A modified polyvinyl acetal resin for ceramic green sheets used for ceramic green sheets,
Contains a structural unit having an alkyl modification group having 4 or more carbon atoms in the side chain,
The structural unit having an alkyl modifying group having 4 or more carbon atoms in the side chain includes a structural unit represented by the following formula (2),
A modified polyvinyl acetal resin for ceramic green sheets , characterized in that the degree of acetalization is 0.1 to 40 mol% .

In formula (2), R ³ represents an alkyl group having 6 to 20 carbon atoms. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1, containing 0.1 to 5 mol% of the structural unit having the alkyl modifying group having 4 or more carbon atoms in its side chain. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1 or 2, characterized in that it consists only of a constitutional unit having a hydroxyl group, a constitutional unit having an acetyl group, and a constitutional unit having an acetal group. The modified polyvinyl acetal resin according to claim 1 or 2, wherein the structural unit having an alkyl modifying group having 4 or more carbon atoms in its side chain further includes a structural unit represented by the following formula (1).

In formula (1), R ¹ represents an alkyl group having 4 to 25 carbon atoms, and R ² represents a single bond, O, COO, or CONH. The modified polyvinyl acetal resin for ceramic green sheets according to claim 4 , wherein in formula (1), R ¹ is a branched alkyl group. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1, 2, 3, 4 or 5 , which has a degree of polymerization of 500 to 4,500. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1, 2, 3, 4, 5 or 6 , characterized in that the amount of hydroxyl groups is 40 to 99 mol%. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1, 2, 3, 4, 5, 6 or 7 , characterized in that the acetyl group content is 0.1 to 20 mol%. In an aqueous solution with a solid content concentration of 5% by weight, the ratio of the maximum value to the minimum value of viscosity (maximum value of viscosity/minimum value of viscosity) in the shear rate range of 1 to 100 [1/s] at a temperature of 25°C is 1. The modified polyvinyl acetal resin for ceramic green sheets according to claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that the polyvinyl acetal resin has a molecular weight of 5 to 150. A modified polyvinyl acetal resin composition for ceramic green sheets, comprising the modified polyvinyl acetal resin for ceramic green sheets according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9 .