JP2009001631A - Modified polyvinyl acetal resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified polyvinyl acetal resin that is internally plasticized. <P>SOLUTION: The modified polyvinyl acetal resin has a structure wherein a C2-C12 alkylene oxide is added to a hydroxy group in the polyvinyl acetal resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internally plasticized modified polyvinyl acetal resin.

  Polyvinyl acetal resins represented by polyvinyl butyral are excellent in adhesion to various organic and inorganic substrates, affinity, and solubility in organic solvents. Various adhesives, binders for ceramics, various inks, paints, It is used in a wide range of applications such as safety glass interlayers for buildings and automobiles.

Conventionally, a modified polyvinyl acetal resin obtained by dissolving a residual hydroxyl group of polyvinyl acetal and a glycidyl compound (glycidyl ether, glycidyl ester, etc.) in a solvent and reacting in a homogeneous system is known (Patent Document 1). . According to this method, a modified polyvinyl acetal resin with a small amount of residual hydroxyl groups can be obtained, which is suitable for improving the water resistance of the ink coating film when applied to ink applications.
However, in this method, since a solvent is used, problems such as poor productivity and unfavorable environment arise. In addition, in the reaction in solution, oligomerization of alkylene oxide is likely to proceed, so that uniform modification of polyvinyl acetal becomes difficult. Furthermore, when an ether bond or an ester bond is introduced, there is a problem that hydrophilicity increases and dispersibility of various inorganic substances deteriorates.

  On the other hand, a polyvinyl butyral resin having a polyalkylene oxide side chain prepared by modifying polyvinyl alcohol with polyalkylene oxide or the like and then acetalizing it is known (Patent Document 2). However, this method has a problem that turbidity occurs when processed into a film or sheet due to the presence of unreacted polyalkylene oxide. In addition, when used as a ceramic binder, the polyalkylene oxide side chain is long, so that it exhibits a phase separation behavior when the solvent is dried for producing a green sheet, and it is difficult to obtain a high-density ceramic.

JP 2001-220426 A Japanese Patent Laid-Open No. 06-263521

  An object of the present invention is to provide a novel modified polyvinyl acetal resin that is plasticized and has a small amount of metal and is suitable as a raw material for films and sheets, and as a binder for ceramics, inks, paints and the like. .

  The present inventors have found that the above problems can be solved by a modified polyvinyl acetal resin having a structure in which an alkylene oxide having 2 to 12 carbon atoms is added to a hydroxyl group in the polyvinyl acetal resin, and completed the present invention.

  Such a modified polyvinyl acetal resin is preferably obtained by reacting a polyvinyl acetal resin and an alkylene oxide in the presence of a catalyst, and more preferably by reacting in a molten state without using a solvent. can get.

  The modified polyvinyl acetal resin of the present invention is characterized in that it is internally plasticized (glass transition temperature is lowered). When the modified polyvinyl acetal resin is processed into a film or sheet and used, a large amount of plasticizer The problems of deterioration of physical properties due to the addition, bleeding out of the plasticizer, and migration to other resins are solved. Further, when used as various binders, it has a feature of low viscosity and excellent handleability while maintaining high dispersibility and high mechanical strength.

  The modified polyvinyl acetal resin of the present invention has a structure in which an alkylene oxide having 2 to 12 carbon atoms is added, and the added amount of alkylene oxide is 1 to 30 mol% with respect to all vinyl units in the polyvinyl acetal resin. . A more preferable form is a polyvinyl acetal resin having a structure to which an alkylene oxide having 2 to 4 carbon atoms is added. Alkylene oxide having a large molecular weight is excellent in the internal plasticizing effect, but removal of unreacted matter becomes a problem, and may cause undesirable turbidity when processed into a film or sheet.

  Although there is no restriction | limiting in particular as polyvinyl acetal resin used for adding a C2-C12 alkylene oxide, The thing which acetalized polyvinyl alcohol with a C2-C8 aldehyde is preferable. Examples of the aldehyde having 2 to 8 carbon atoms include acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde, 2-ethylbutyraldehyde, octylaldehyde, 2-ethylhexylaldehyde, and the like. You may use, and may use 2 or more types together. Among these, aldehydes having 4 to 6 carbon atoms, particularly n-butyraldehyde are preferably used.

The degree of acetalization of the modified polyvinyl acetal resin is preferably 40 to 85 mol%, and more preferably 50 to 85 mol%. Moreover, it is preferable that content of a vinyl acetate unit in modified polyvinyl acetal resin is 0.01-30 mol%, and content of a vinyl alcohol unit is 10-50 mol%. Moreover, 1-30 mol% is preferable and, as for content of the vinyl alcohol unit which the alkylene oxide added, 3-20 mol% is more preferable.
In addition, the above-mentioned degree of acetalization (content of acetal unit), content of vinyl acetate unit, content of vinyl alcohol unit, content of vinyl alcohol unit added with alkylene oxide is the sum of these contents It is a value relative to the amount (total vinyl units).

The modified polyvinyl acetal resin of the present invention is suitably obtained, for example, by reacting a polyvinyl acetal resin with an alkylene oxide compound in the presence of a catalyst.
As the method, (1) a method in which a polyvinyl acetal resin is mixed and reacted with an alkylene oxide and a catalyst in a molten state, (2) a polyvinyl acetal resin is dissolved in a solvent, and an alkylene oxide and a catalyst are mixed with this. The method of making it react is mentioned.

  Although there is no restriction | limiting in particular about the method of said (1), A single screw extruder, a twin screw extruder, or a multi-screw extruder more than two screws is used, Polyvinyl acetal resin and an alkylene oxide are 130 degreeC ~ It is preferable to make it react at the temperature of about 300 degreeC. When a twin screw extruder or a multi-screw extruder of two or more screws is used, it is easy to increase the pressure in the reaction part by changing the screw configuration, and the reaction between the polyvinyl acetal resin and the alkylene oxide compound is efficiently performed. You can do it. In the case of using a single screw extruder, it is possible to increase the pressure in the reaction section by connecting two or more extruders and arranging a valve in the resin flow path therebetween. Similarly, two or more twin-screw extruders or two or more multi-screw extruders may be connected.

  As a catalyst used for reaction, what contains the ion of the metal which belongs to periodic table group 3-12 is used. Among these, ions of metals belonging to Group 3 or Group 12 of the Periodic Table are suitable because they have moderate Lewis acidity, and ions of zinc, yttrium, and gadolinium are more preferable. Among them, a catalyst containing zinc ions is optimal because it has extremely high catalytic activity, and the resulting modified polyvinyl acetal resin has excellent thermal stability.

The anion species of the catalyst containing a metal ion belonging to Groups 3 to 12 of the periodic table is not particularly limited, but it is preferable that the conjugate acid contains a monovalent anion which is a strong acid equal to or higher than sulfuric acid. . Monovalent anions in which the conjugate acid is a strong acid equivalent to or higher than sulfuric acid include sulfonate ions such as methanesulfonate ion, ethanesulfonate ion, trifluoromethanesulfonate ion, benzenesulfonate ion, toluenesulfonate ion; chlorine Halogen ions such as ions, bromine ions and iodine ions; perchlorate ions; tetrafluoroborate ions (BF ⁴⁻ ), hexafluorophosphate ions (PF ⁶⁻ ), hexafluoroarsinate ions (AsF ⁶⁻ ), hexafluoro Anions having four or more fluorine atoms such as antimonate ions; tetraphenylborate derivative ions such as tetrakis (pentafluorophenyl) borate ions; tetrakis (3,5-bis (trifluoromethyl) phenyl) borate, bis (un Ca 7,8-dicarbaundecaborate deca borate) cobalt (III) ion, bis (such undecapeptide 7,8-dicarbaundecaborate deca borate) iron (III) ions carborane derivative ions and the like. Among them, sulfonate ions are preferable, and suitable sulfonate ions include methanesulfonate ions, trifluoromethanesulfonate ions, benzenesulfonate ions, and toluenesulfonate ions, and trifluoromethanesulfonate ions are most suitable.

  The amount of catalyst is preferably 0.1 to 200 ppm as the amount of metal ions of the catalyst used. This substantially corresponds to the metal ion content of 0.1 to 200 ppm being the highest among the metals belonging to Groups 3 to 12 of the periodic table. The catalyst amount is more preferably 1 to 150 ppm, and further preferably 5 to 100 ppm. When the amount of the catalyst is large, it tends to be a drawback when used as a ceramic binder, and when used as a film or sheet, it causes turbidity. Moreover, it becomes difficult to deactivate the catalyst sufficiently, and the stability of the resulting modified polyvinyl acetal resin is lowered.

  The catalyst used for the reaction needs to be deactivated promptly after the reaction in order to prevent the modified polyvinyl acetal resin from being altered. The catalyst deactivator used is not particularly limited as long as it reduces the function of the catalyst as a Lewis acid. An alkali metal salt is preferably used, and it is effective to use an alkali metal salt of a weak acid. The cation species of the alkali metal salt used for the catalyst deactivator is not particularly limited, and sodium salt, potassium salt and lithium salt are preferred as examples. Also, the anionic species is not particularly limited, and carboxylates, phosphates and phosphonates are exemplified as suitable ones. Another preferred method is to add a chelating agent that strongly coordinates to the metal ions constituting the catalyst.

  Suitable chelating agents used as catalyst deactivators include oxycarboxylates, aminocarboxylates, aminophosphonates and the like. Specifically, examples of the oxycarboxylate include disodium citrate, disodium tartrate, and disodium malate. Aminocarboxylates include nitrilotriacetic acid trisodium, ethylenediaminetetraacetic acid disodium, ethylenediaminetetraacetic acid trisodium, ethylenediaminetetraacetic acid tripotassium, diethylenetriaminepentaacetic acid trisodium, 1,2-cyclohexanediamine tetraacetic acid trisodium, ethylenediamine diacetate. Illustrative examples include monosodium acetate and monosodium N- (hydroxyethyl) iminodiacetic acid. Examples of aminophosphonates include nitrilotrismethylenephosphonic acid hexasodium, ethylenediaminetetra (methylenephosphonic acid) octasodium, and the like. Of these, alkali metal salts of ethylenediaminetetraacetic acid are preferred.

  The addition amount of the catalyst deactivator is not particularly limited and is appropriately adjusted depending on the type of metal ion contained in the catalyst, the number of coordination sites of the chelating agent, etc. It is preferable that the molar ratio of the deactivator is 0.2 to 10. When the ratio is less than 0.2, the catalyst is not sufficiently deactivated, more preferably 0.5 or more, and even more preferably 1 or more. On the other hand, when the ratio exceeds 10, the resulting modified polyvinyl acetal resin is likely to be colored, more preferably 5 or less, and even more preferably 3 or less.

  The method for introducing the catalyst deactivator into the extruder is not particularly limited. However, in order to uniformly disperse the catalyst deactivator, it is preferably introduced as a solution of the catalyst deactivator into the molten modified polyvinyl acetal resin. In consideration of the solubility of the catalyst deactivator and the influence on the surrounding environment, it is preferably added as an aqueous solution.

  The catalyst deactivator may be added to the extruder after melt-kneading the polyvinyl acetal resin and the alkylene oxide in the presence of the catalyst. In particular, the catalyst deactivation is performed after removing the unreacted alkylene oxide. It is preferable to add an agent. It is also preferable to remove the solvent used by venting or the like.

  From the viewpoint of carrying out the reaction smoothly, it is preferable to remove moisture and oxygen from the system. For this reason, moisture and oxygen may be removed using a vent or the like before the alkylene oxide is added into the extruder.

  In the method (2), a modified polyvinyl acetal resin is obtained by mixing and reacting an alkylene oxide with a solution of the polyvinyl acetal resin in the presence of an acid catalyst or an alkali catalyst. Moreover, a modified polyvinyl acetal resin can also be produced by dissolving a polyvinyl acetal resin and an alkylene oxide in a reaction solvent and performing a heat treatment. As the reaction solvent, polar aprotic solvents which are good solvents for polyvinyl acetal resins such as acetone, methyl ethyl ketone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone are preferable.

  Catalysts used for the reaction include acid catalysts such as p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid and boron trifluoride, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide. An alkali catalyst such as Of these, it is preferable to use an acid catalyst. As a catalyst amount, about 0.0001-10 weight part is suitable with respect to 100 weight part of polyvinyl acetal resin. The reaction temperature is suitably from room temperature to 150 ° C.

  Among these methods, a method in which the polyvinyl acetal resin is reacted in a molten state is preferable in consideration of simplification of the process, ease of reaction control, productivity, and the like.

  The polyvinyl alcohol used as a raw material in the present invention can be obtained by a conventionally known method, that is, by polymerizing a vinyl ester monomer and saponifying the obtained polymer. As a method for polymerizing the vinyl ester monomer, conventionally known methods such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method can be employed. As the catalyst used for the polymerization, an azo catalyst, a peroxide catalyst, a redox catalyst or the like is appropriately selected according to the polymerization method employed. The saponification reaction can be carried out by alcoholysis or hydrolysis using a conventionally known alkali catalyst or acid catalyst. Among them, methanol is used as a solvent, and saponification reaction using caustic soda (NaOH) as a catalyst is simple. Most preferred.

  Examples of 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. Vinyl, vinyl stearate, vinyl oleate, vinyl benzoate and the like can be mentioned, with vinyl acetate being particularly preferred.

  In addition, the vinyl ester monomer can be used by being copolymerized with other monomer units as long as the gist of the present invention is not impaired. Examples of the monomer units include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and its salts; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate Acrylates such as n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and salts thereof; methyl methacrylate, methacryl Methacrylic acid such as ethyl acetate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate Beauty treatment Acrylamide, N-methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, acrylamide propane sulfonic acid and its salt, acrylamidopropyldimethylamine and its salt, quaternary salt thereof, N-methylol acrylamide And acrylamide derivatives thereof; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamidepropyldimethylamine and salts thereof, quaternary salts thereof, N-methylolmethacrylate Methacrylamide derivatives such as amides and derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether Vinyl ethers such as tellurium, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; Examples thereof include vinylidene halides such as vinylidene and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and salts thereof, esters or anhydrides thereof, vinylsilyl compounds such as vinyltrimethoxysilane, and isopropenyl acetate. These monomer units are usually used in a proportion of less than 10 mol% with respect to the vinyl ester monomer.

  The preferable polymerization degree of polyvinyl alcohol is 100-3500, and more preferably 200-2500.

In order to produce a polyvinyl acetal resin by acetalizing polyvinyl alcohol, for example, the following method can be employed.
First, an aqueous solution of polyvinyl alcohol having a concentration of 3 to 15% by weight is prepared at a temperature of 80 to 100 ° C. and gradually cooled over 10 to 60 minutes. When the temperature is lowered to −10 to 30 ° C., an aldehyde and an acid catalyst are added, and an acetalization reaction is performed for 30 to 300 minutes while keeping the temperature constant. Thereafter, the reaction solution is heated to a temperature of 40 to 80 ° C. over 30 to 200 minutes, and held at that temperature for 1 to 6 hours. Next, the reaction liquid is preferably cooled to room temperature, washed with water, a neutralizing agent such as an alkali is added, and the resultant is dried to obtain a target polyvinyl acetal resin.

  It does not specifically limit as an acid catalyst used for acetalization reaction, Any organic acid and inorganic acid can be used, For example, an acetic acid, paratoluenesulfonic acid, nitric acid, a sulfuric acid, hydrochloric acid etc. are mentioned. Among these, hydrochloric acid, sulfuric acid, and nitric acid are more generally used, and hydrochloric acid is particularly preferably used.

  Usually, the polyvinyl acetal resin often contains around 100 ppm of an alkali-derived alkali metal salt used for neutralizing the acid catalyst used in the acetalization reaction. On the other hand, when producing a modified polyvinyl acetal resin, the catalyst itself used to modify the polyvinyl acetal resin is deactivated by the alkali metal salt, so the catalyst is usually used in a larger number of moles than the amount of alkali metal contained. There is a need to. Furthermore, in order to deactivate the catalyst used for modification after the reaction, an alkali metal salt or the like having the same number of moles as that of the catalyst used for modification is usually used. Therefore, the amount of alkali metal in the modified polyvinyl acetal resin is usually more than twice the amount of alkali metal in the raw material polyvinyl acetal resin to be used. When the amount of the alkali metal is large, the adhesion to the substrate may be lowered when processed into a film or the like, or turbidity may be caused by water absorption. Further, when used as a ceramic binder for a multilayer capacitor or the like, it may cause an electrical defect, so that the content is preferably as low as possible. That is, the amount of alkali metal in the modified polyvinyl acetal resin is preferably 200 ppm or less, more preferably 150 ppm or less, further preferably 100 ppm or less, and particularly preferably 80 ppm or less.

In order to reduce the amount of alkali metal in the modified polyvinyl acetal resin, it is preferable to reduce the amount of alkali metal in the raw material polyvinyl acetal resin as much as possible.
By reducing the amount of alkali metal salt in the raw material polyvinyl acetal resin, the amount of alkali metal salt that is a catalyst deactivator to be added can be reduced, and the amount of alkali metal in the resulting modified polyvinyl acetal resin can be reduced. .

  Examples of the method for reducing the amount of alkali metal in the raw material polyvinyl acetal resin include a method of reducing the particle size of the polyvinyl acetal resin by controlling the conditions of the acetalization reaction, for example, the reaction temperature, reaction rate, and stirring rate. . Preferably, the polyvinyl acetal resin is preferably composed of secondary particles that are aggregates of primary particles, and is particularly an aggregate composed of primary particles having an average particle size of 5 μm or less and a maximum particle size of 10 μm. preferable. Moreover, it is preferable to prevent primary particles from fusing more than necessary by controlling the reaction temperature and the like. Examples of other methods include a method for enhancing the washing after neutralization, for example, a method for increasing the amount of washing water, a method for increasing the number of washings, a method for performing ultrasonic washing, and the like.

  In order to improve the weather resistance, an antioxidant, an ultraviolet absorber, an ultraviolet stabilizer, and other stabilizers may be added to the modified polyvinyl acetal resin of the present invention.

  Antioxidants include phenol-based, sulfur-based, phosphorus-based and the like, and particularly 2.6-di-t-butyl-p-cresol (BHT), butylated hydroxyanizole (BHA), 2,6- Di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2′-methylene-bis- (4-methyl-6-butylphenol) ), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis -(3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-hydroxy-5-tert-butylphenyl) butane, tetrakis [methylene-3- (3 ', 5'- Til-4'-hydroxyphenyl) propionate] methane, 1,1,3-tris- (2-methyl-4-hydroxy-5-t-butylphenol) butane, 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis (3,3'-bis- (4'-hydroxy-3'-t-butylphenol) butyric acid) glycol ester, etc. Preferably used. The addition amount of the antioxidant is preferably 0.02 to 3 parts by weight, and more preferably 0.05 to 2 parts by weight.

  Examples of the ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2′-hydroxy- 3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'- Hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- [2 Benzotriazole ultraviolet absorbers such as '-hydroxy-3'-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,4- Dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy Benzophenone ultraviolet absorbers such as -4,4'-dimethoxybenzophenone and 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano And cyanoacrylate-based ultraviolet absorbers such as −3,3′-diphenylacrylate.

  As the UV stabilizer, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4- Butanetetracarboxylate, Sanol LS-770, Sanol LS-765, Sanol LS-2626, Chimassob 944LD, Thinuvin-662, Thinuvin-622LD, Mark LA-57, Mark LA-77, Mark LA-62, Mark LA-62 Hindered amine UV stabilizers such as Mark LA-63, Mark LA-68, Mark LA-82, Mark LA-87, Goodrite UV-3404, nickel [2,2′-thiobis (4-t-octyl) phenolate] -N-butylamine, Neckel dibutyldithiocarbamate, nickel bis [o-ethyl-3,5- (di-t-butyl-4-hydroxybenzyl)] phosphate, cobalt dicyclohexyldithiophosphate, [1-phenyl-3-methyl-4-decanonyl- Pyrazolate (5) 2] Metal complex salt type UV stabilizers such as nickel are listed.

  Furthermore, a plasticizer, an adhesion improver, a heat ray absorbent, a colorant, a filler, a fluidity improver, and the like may be added depending on the application.

  These additives may be added either during the production of the polyvinyl acetal or during the modification of the modified polyvinyl acetal resin, or may be added after the production and before use in various applications.

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

Example 1
(Preparation of polyvinyl butyral resin)
A reaction tank having an internal volume of 2 m ³ is charged with 1350 kg of ion exchange water and 110 kg of polyvinyl alcohol (PVA-1) (polymerization degree 1700, saponification degree 98 mol%) (PVA concentration 7.5%), and the content is 95 ° C. The solution was completely heated and dissolved. Next, after cooling to 10 ° C. with stirring, 64 kg of butyraldehyde and 90 L of 20% hydrochloric acid were added, and an acetalization reaction was performed for 150 minutes. Thereafter, the temperature was raised to 50 ° C. over 60 minutes, held at 50 ° C. for 120 minutes, and then cooled to room temperature. The reaction solution slurry was transferred to a filtration tank and filtered, and the resulting resin was washed 5 times with ion-exchanged water and then neutralized with an aqueous sodium hydroxide solution. This was filtered, further washed 10 times with water, and then dried to obtain polyvinyl butyral (PVB-A1). The obtained PVB-A1 had an acetalization degree of 71 mol%, a residual vinyl acetate group content of 2 mol%, and a sodium content of 18 ppm.
The degree of butyralization of the polyvinyl butyral resin, the content of residual vinyl acetate groups, and the amount of residual sodium were measured according to the following methods.

(Measurement of degree of butyralization of polyvinyl butyral resin, content of vinyl acetate group)
^It was measured by ¹ H-NMR method.
(Measurement of sodium content in polyvinyl butyral resin)
It was measured by ICP emission analysis.

(Preparation of modification catalyst)
28 parts by weight of zinc acetylacetonate monohydrate was mixed with 957 parts by weight of 1,2-dimethoxyethane to obtain a mixed solution. While stirring, 15 parts by weight of trifluoromethanesulfonic acid is added to the obtained mixed solution, and a modification catalyst (1 mol of trifluoromethanesulfonic acid is mixed with 1 mol of zinc acetylacetonate monohydrate) is contained. A solution was prepared.

(Manufacture of modified polyvinyl acetal resin)
The twin screw extruder was set to 200 ° C. to 220 ° C., PVB-A1 resin was fed thereto at 20 kg / hr, propylene oxide was fed from the side feed port at 1.55 kg / hr, and the above was further prepared. The solution of the modifying catalyst was added so as to be 1 μmol / g with respect to the polyvinyl butyral resin. After removing unreacted propylene oxide in the latter half of the extruder under reduced pressure, 0.2 mol / l-sodium acetate aqueous solution was added as a catalyst deactivator so as to be 1 μmol / g with respect to the polyvinyl butyral resin. Water was distilled off under reduced pressure near the tip. The reaction temperature was about 237 ° C. The extruded strand-shaped resin was cooled with water and then pelletized with a pelletizer to obtain a modified polyvinyl acetal resin (PVB-B1). The degree of acetalization of the obtained PVB-B1 was 70 mol%, the content of the remaining vinyl acetate groups was 2 mol%, and the amount of propylene oxide modification was 5 mol%. Moreover, the amount of sodium in PVB-B1 was 40 ppm, and the amount of zinc was 63 ppm.
In addition, the modified | denatured polyvinyl butyral resin modified | denatured the propylene oxide amount and the amount of residual zinc were measured in accordance with the following method.

(Measurement of amount of propylene oxide modification of modified polyvinyl butyral resin)
^It was measured by ¹ H-NMR method.
(Measurement of zinc content in modified polyvinyl butyral resin)
It was measured by ICP emission analysis.

The glass transition temperature of the obtained modified polyvinyl butyral resin PVB-B1 was 66.3 ° C. Moreover, the glass transition temperature of polyvinyl butyral resin PVB-A1 before modification was 72.2 ° C., and the internal plasticizing effect was confirmed. The glass transition temperature was measured according to the following method.
(Measurement of glass transition temperature)
It measured using DSC with the temperature increase rate of 10 degree-C / min.

Example 2
A modified polyvinyl butyral resin PVB-B2 was obtained in the same manner as in Example 1 except that the feed amount of propylene oxide was doubled. The obtained PVB-B2 had an acetalization degree of 70 mol%, a residual vinyl acetate group content of 2 mol%, and a propylene oxide modification amount of 9 mol%. Moreover, the amount of sodium in PVB-B2 was 42 ppm, and the amount of zinc was 67 ppm. The glass transition temperature of the obtained modified polyvinyl butyral resin PVB-B2 was 61.8 ° C., and the internal plasticizing effect was confirmed.

Comparative Example 1
(Preparation of polyvinyl butyral resin)
Polyvinyl butyral (PVB-A2) was obtained in the same manner as in Example 1 except that the number of washings after neutralization was changed to 3. The degree of acetalization of the obtained PVB-A2 was 71 mol%, and the content of the remaining vinyl acetate groups was 2 mol%. Moreover, the amount of sodium in PVB-A2 was 102 ppm.
(Manufacture of modified polyvinyl acetal resin)
A reaction was attempted in the same manner as in Example 1 except that PVB-A2 was used instead of PVB-A1, but no exotherm was observed due to the reaction, and the reaction did not proceed. Therefore, when the catalyst amount was gradually increased, heat generation due to the reaction was observed at the point where the catalyst amount was increased from 1 μmol / g of Example 1 to 5 μmol / g. The reaction was continued at a catalyst amount of 5 μmol / g to obtain a modified polyvinyl acetal resin PVB-B3. The obtained PVB-B3 had an acetalization degree of 70 mol%, a residual vinyl acetate group content of 2 mol%, and a propylene oxide modification amount of 5 mol%. Moreover, the amount of sodium in PVB-B3 was 220 ppm, and the amount of zinc was 320 ppm.

Example 3
A polyvinyl butyral resin PVB-A3 was obtained in the same manner as in Example 1 except that PVA-3 (polymerization degree 600, saponification degree 98%) was used instead of PVA-1 and the reaction temperature was 5 ° C. The degree of acetalization of the obtained PVB-A3 was 70 mol%, and the content of the remaining vinyl acetate groups was 2 mol%. Moreover, the amount of sodium in PVB-A3 was 16 ppm. The glass transition temperature of PVB-A3 was 67.9 ° C., and the viscosity of a 10% ethanol solution measured with a B-type viscometer at 69 ° C. was 69 mPa · s. Further, in the same manner as in Example 1, a modified polyvinyl butyral resin PVB-B4 was obtained. The obtained PVB-B4 had an acetalization degree of 69 mol%, a residual vinyl acetate group content of 2 mol%, and a propylene oxide modification amount of 6 mol%. Moreover, the amount of sodium in PVB-B4 was 41 ppm, and the amount of zinc was 65 ppm. Further, PVB-B4 had a glass transition temperature of 62.1 ° C. and a 10% ethanol solution viscosity of 45 mPa · s, and the internal plasticizing effect was confirmed.

Example 4
A modified polyvinyl butyral resin PVB-B5 was obtained in the same manner as in Example 3 except that the feed amount of propylene oxide was doubled. The obtained modified polyvinyl butyral resin PVB-B5 had an acetalization degree of 69 mol%, a residual vinyl acetate group content of 2 mol%, and a propylene oxide modification amount of 9 mol%. Moreover, the amount of sodium in PVB-B5 was 43 ppm, and the amount of zinc was 68 ppm. Moreover, the glass transition temperature of PVB-B5 was 58.3 ° C., the viscosity of a 10% ethanol solution measured with a B-type viscometer at 20 ° C. was 38 mPa · s, and the internal plasticizing effect was confirmed.

  The modified polyvinyl acetal resin of the present invention is useful as a raw material for a film or sheet material. In addition, since the viscosity is low even when the degree of polymerization is high, and the hydrophilic-hydrophobic balance is balanced and the dispersibility of the inorganic substance is excellent, various binders such as ceramics, inks, paints, powders, etc. It is used as a binder or adhesive for paints, X-ray dry films, conductive pastes, etc., and is particularly useful as a binder for thin film ceramics.

Claims (4)

  Modification having a structure in which an alkylene oxide having 2 to 12 carbon atoms is added to a hydroxyl group in a polyvinyl acetal resin, and the addition amount of the alkylene oxide is 1 to 30 mol% with respect to all vinyl units in the polyvinyl acetal resin. Polyvinyl acetal resin.   The modified polyvinyl acetal resin according to claim 1, wherein the alkylene oxide is any one of ethylene oxide, propylene oxide, and butylene oxide.   The modified polyvinyl acetal resin according to claim 1 or 2, wherein the alkali metal content is 200 ppm or less.   The modified polyvinyl acetal resin according to any one of claims 1 to 3, wherein the content of ions of the metal having the largest content among the metals belonging to Groups 3 to 12 of the periodic table is 0.1 to 200 ppm.