JP3766457B2 - Acetoacetate group-containing polyvinyl alcohol resin and process for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an acetoacetate group-containing polyvinyl alcohol resin excellent in transparency and aqueous solution stability and a method for producing the same.
[0002]
[Prior art]
A conventional acetoacetate group-containing PVA resin (hereinafter abbreviated as AA-modified PVA) is produced by reacting a polyvinyl alcohol resin (hereinafter abbreviated as PVA) with diketene, specifically in an acetic acid solvent. A method of dissolving or dispersing PVA and adding diketene to this, and a method of dissolving PVA in a solvent such as dimethylformamide or dioxane in advance and then adding and reacting with diketene have long been known. .
[0003]
However, in these conventional techniques, a precipitant is added to the reaction product in order to obtain the reaction product from the reaction solution, and after the product is precipitated, the product and the mother liquor are separated, and the solvent is separated from the separated mother liquor. Many complicated processes such as recovery of the precipitating agent and removal of the solvent and precipitant from the separated product are indispensable, and this process inevitably greatly affects the product cost. Was disadvantageous.
[0004]
Therefore, as a result of repeated studies on a method for obtaining AA-modified PVA more easily and at a lower cost than the prior art, the present applicant has obtained a method for obtaining AA-modified PVA by directly contacting PVA with diketene gas or liquid diketene. As a result, patent applications have been filed previously (Japanese Patent Laid-Open Nos. 55-137107 and 55-94904). In this method, unreacted diketene can be easily removed, the post-treatment process is simplified, and a small amount of catalyst may be used. However, AA-PVA is slightly colored, and an undissolved part is generated, and AA-PVA is produced. It was a problem in some applications that use.
[0005]
As an improvement technique, the present applicant has also filed a patent application for a method for obtaining AA-modified PVA by coexisting an organic acid within the limits that can be occluded in PVA (Japanese Patent Laid-Open No. 57-40508).
By this method, the coloration problem of AA-PVA and the problem of undissolved matter formation were roughly solved.
[0006]
[Problems to be solved by the invention]
However, in recent years, AA-PVA has been used in large quantities for a wide range of applications due to its superior characteristics, and under the sophistication of technology, higher-quality physical properties that have hardly been a problem in the past are required. It has become.
When PVA with high crystallinity is converted to acetoacetate ester, all of the AA-PVA produced by the above-mentioned methods have slightly poor transparency of the aqueous solution, and many undissolved products are produced. When stored for a long period of time, when the powder after storage is made into an aqueous solution, many undissolved components are generated. In this regard, it has been found that there is room for further improvement.
[0007]
[Means for Solving the Problems]
The present inventor has eagerly studied to overcome such problems, and has studied the degree of acetoacetate esterification (hereinafter abbreviated as AA degree) for each particle size of AA-modified PVA. 74, 74 to 105, 105 to 177, 177 to 297, 297 to 500, and 500 to 1680 μm, the degree of acetoacetate esterification of each acetoacetate group-containing polyvinyl alcohol resin fractionated to each particle size was neutralized. Calculated from the alkali consumption by titration, AA-PVA with a value obtained by dividing the highest degree of acetoacetate esterification by the lowest degree of AA conversion of 3.0 to 1.0 is excellent in transparency of the aqueous solution and is not dissolved Thus, the present inventors have found that the viscosity stability is good even when stored in a powder for a long period of time, and the present invention has been completed.
[0008]
The particle size of 44 to 74 μm means a particle size screened by 350 mesh (44 μm) on a standard wire mesh and a 200 mesh (74 μm) pass, and 74 to 105 μm means 200 mesh (74 μm) on, 145 The particle size screened by the mesh (105 μm) pass is 105 to 177 μm is 145 mesh (105 μm) on, the particle size screened by the 80 mesh (177 μm) pass is 177 to 297 μm and 80 mesh (177 μm) ON, particle size screened by 48 mesh (297 μm) pass, 297-500 μm is 48 mesh (297 μm) ON, particle size screened by 32 mesh (500 μm) pass, 500- 1680μm means 32 mesh (500μm) Mean a particle size screened by a 10.5 mesh (1680 μm) pass.
[0009]
As a method for measuring the AA degree distribution, after the AA PVA is fractionated into particle sizes of 44 to 74, 74 to 105, 105 to 177, 177 to 297, 297 to 500, and 500 to 1680 μm as described above, Each AA degree is calculated from the alkali consumption by neutralization titration, and the highest AA degree is divided by the lowest AA degree. However, when the particle size distribution of the AA-PVA is narrow and all of the specific particle size is included, and only a single AA degree value is calculated, the AA degree degree distribution is set to 1.0.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The AA-modified PVA of the present invention introduces an acetoacetate group into PVA by reacting PVA with diketene, reacting PVA with acetoacetate, copolymerizing vinyl acetoacetate, etc. The AA degree distribution is defined as described above, and the AA degree distribution is required to be 3.0 to 1.0, preferably 2.0 to 1.0, and more preferably, 1.5 to 1.0.
[0011]
When the AA degree distribution exceeds 3.0, a small amount of undissolved material is present when the AA PVA is dissolved in water, the transparency is lowered, or the viscosity when the AA PVA is stored as an aqueous solution for a long period of time. In addition, after the AA-PVA is stored as a powder for a long period of time, the viscosity when it is made into an aqueous solution is higher than the viscosity when the powder immediately after production is made into an aqueous solution, and the object of the present invention cannot be achieved.
[0012]
The method for obtaining the AA-PVA having the AA-degree distribution as described above is not particularly limited. For example, the degree of swelling, dissolution rate, particle size, etc. of the raw material PVA are adjusted to a specific range, or after AA-PVA production, AA For example, the particle size fraction having a high degree of conversion or a low particle size fraction may be removed, or the average AA degree of AA-modified PVA may be adjusted to a low level. It is practical to adjust.
[0013]
Hereinafter, the adjustment of the raw material PVA will be described in detail.
Examples of such raw material PVA include PVA derivatives obtained by saponifying a lower alcohol solution of polyvinyl acetate with a saponification catalyst such as alkali, and a copolymer of a vinyl acetate and a monomer copolymerizable with vinyl acetate. A saponified compound may be mentioned.
[0014]
The saponification degree of the vinyl acetate component is preferably 5 to 100 mol%, more preferably 75 to 99 mol%. Although it does not specifically limit as an average degree of polymerization, Preferably it is 200-3000.
[0015]
Examples of the monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid and the like. Unsaturated acids or salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid or the like Salt, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallylvinylketone, N-vinylpyrrole , Vinyl chloride, vinylidene chloride, polyoxyethylene (meth) allyl ether, polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) Polyoxyalkylene (meth) acrylates such as acrylate, polyoxyalkylene (meth) acrylamides such as polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1 -Dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinyl Triethanolamine, a copolymer saponified product of a polyoxypropylene vinyl amine.
[0016]
In the present invention, the swelling degree and elution rate of the PVA are adjusted as follows. That is, the swelling degree and elution rate of PVA in the present invention are defined by the following formulas (1) and (2), and the swelling degree needs to be 1.0 or more, preferably 1. It is 0 or more and 500 or less, More preferably, it is 3.0 or more and 200 or less. The elution rate needs to be 3.0% or more, preferably 3.0% or more and 97.0% or less, more preferably 5.0% or more and 60.0% or less.
(1) Swelling degree = (A−B) /B≧1.0
(2) Elution rate (%) = (C / 30) × 100 ≧ 3.0
A: After adding 270 g of water to 30 g of PVA and leaving it to stand at 25 ° C. for 24 hours, the weight (g) of the water-absorbed and swollen PVA remaining on the filter paper (No. 2) after filtering for 10 minutes by suction at a vacuum degree of 100 mmHg
B: Weight (g) when the water-absorbed PVA was dried at 105 ° C. to become a constant weight.
C: 270 g of water was added to 30 g of PVA, left at 25 ° C. for 24 hours, filtered with suction at a vacuum of 100 mmHg for 10 minutes, and water and volatile components were distilled off from the filtrate obtained using the filter paper . Non-volatile component weight (g)
[0017]
When the degree of swelling is less than 1.0 or the elution rate is less than 3.0%, it becomes difficult to obtain an AA-modified PVA having an AA degree distribution of 3.0 or less.
[0018]
In order to control the swelling degree and elution rate of the raw material PVA, there is a method such as a method of adjusting the crystallinity by heat treatment while leaving the raw material PVA stationary or flowing. Is preferred.
[0019]
In this invention, the effect of this invention can be acquired more notably by making the particle size of said raw material PVA into a powder of 20-5000 micrometers, and also 44-168 micrometers.
[0020]
If the particle size exceeds 5000 μm, the contact between the PVA particles and the diketene is not uniform, and the reaction rate of the diketene is reduced, which is not preferable. When the particle size is less than 20 μm, the particles are easily fused by the heat of reaction, and further post-treatment such as washing and drying Is not preferable.
[0021]
The particle size of the PVA may be adjusted with a standard sieve after the production of PVA, or may be classified by wind force.
[0022]
Some of these raw material PVA powders contain several percent of alcohols, esters and moisture in the production process, and these components react with diketene and consume diketene. Since the reaction rate is lowered, it is desirable to reduce the reaction rate as much as possible by performing heating and pressure-reducing operations when it is used for the production of AA-PVA described later.
[0023]
Next, a method for producing AA-PVA using such raw material PVA powder will be described in detail.
In the present invention, if the raw material PVA powder as described above is used, the method for introducing an acetoacetate group into the PVA powder is not particularly limited. As described above, the method of reacting PVA with diketene, and PVA with acetoacetate Any known method such as a reaction method can be employed, but generally, a method of reacting PVA with diketene is preferable because the production process is simple and a high-quality AA-modified PVA can be obtained. In the case of producing by the method of reacting the raw material PVA powder and diketene, it is preferable because the amount of diketene charged is small and the reaction yield of diketene is improved, and this method will be described below.
[0024]
As a method of reacting the raw material PVA powder and the diketene, the PVA powder and the gaseous or liquid diketene may be directly reacted, or after the organic acid is preliminarily adsorbed and occluded in the raw material PVA powder, The liquid or gaseous diketene is sprayed and reacted, or the raw material PVA powder is sprayed and reacted with a mixture of an organic acid and liquid diketene.
[0025]
In the method using an organic acid, acetic acid is the most advantageous as the organic acid, but is not limited thereto, and propionic acid, butyric acid, isobutyric acid, and the like are arbitrarily used.
The amount of the organic acid is preferably within an amount that can be adsorbed and occluded by the raw material PVA powder in the reaction system, in other words, an amount that does not exist the organic acid separated from the resin in the reaction system. Specifically, it is appropriate that 0.1 to 80 parts by weight, preferably 0.5 to 50 parts by weight, particularly preferably 5 to 30 parts by weight of an organic acid coexist with 100 parts by weight of the raw material PVA powder. It is. If the amount is less than 0.1% by weight, it is difficult to obtain the effect of the present invention. On the other hand, if there is an excess of 80% by weight of organic acid, a product having a non-uniform AA degree tends to be obtained and unreacted diketene tends to increase. is there.
[0026]
In order to uniformly adsorb and occlude the organic acid on the raw material PVA powder, any means such as a method of spraying the organic acid alone on the raw material PVA powder, a method of dissolving the organic acid in an appropriate solvent and spraying it can be implemented. It is.
[0027]
As a reaction condition between the raw material PVA powder and the diketene, in the case where the liquid diketene is uniformly adsorbed and absorbed by means such as spraying on the raw material PVA powder, it is heated to a temperature of 20 to 120 ° C. in an inert gas atmosphere, and is predetermined. It is preferable to continue stirring or fluidization for a period of time.
[0028]
When the diketene gas is reacted, the contact temperature is 30 to 250 ° C., preferably 50 to 200 ° C., and the gaseous diketene is brought into contact with the temperature at which the gaseous diketene does not liquefy at the time of contact with the raw material PVA powder and the diketene partial pressure condition. However, it is not a problem that a part of the gas becomes droplets.
The contact time depends on the contact temperature, that is, when the temperature is low, the time is long, and when the temperature is high, the time may be short, and is appropriately selected from the range of 1 minute to 6 hours.
[0029]
When supplying the diketene gas, the diketene gas as it is or a mixed gas of diketene gas and inert gas may be used, and the temperature may be increased after the gas is absorbed by the raw material PVA powder. The gas is preferably contacted after heating.
[0030]
As the catalyst for the AA reaction, basic compounds such as sodium acetate, potassium acetate, primary amine, secondary amine, and tertiary amine are effective, and the amount of the catalyst may be small compared to known reaction methods. And 0.1 to 5.0% by weight based on the raw material PVA powder. Since the raw material PVA powder normally contains sodium acetate, there is often no need to add a catalyst. If the amount of catalyst is too large, side reaction of diketene is likely to occur, which is not preferable.
[0031]
As a reaction apparatus for carrying out AA conversion, an apparatus that can be heated and has a stirrer is sufficient. For example, a kneader, a Henschel mixer, a ribbon blender, other various blenders, and a stirring and drying device.
[0032]
Since the AA-PVA obtained by the present invention has unique performance, it can be used for various applications by utilizing its properties. Specific applications include the following.
[0033]
(1) Molded fiber, film, sheet, pipe, tube, leak-proof film, provisional film, for chemical lace, water-soluble fiber (2) Adhesive-related wood, paper, aluminum foil, plastic, etc., adhesive Agent, rehumidifier, binder for nonwoven fabric, binder for various building materials such as gypsum board and fiberboard, binder for various types of powder granulation, additive for cement and mortar, hot melt adhesive, pressure sensitive adhesive, anionic Paint sticking agent 【0034】
(3) Coating-related paper clear coating agent, paper pigment coating agent, paper internal sizing agent, textile sizing agent, warp sizing agent, textile processing agent, leather finishing agent, paint, anti-fogging agent, metal Corrosion inhibitors, brighteners for galvanizing, antistatic agents, conductive agents, provisional paints (4) Blending agents for hydrophobic resins Antistatic agents for hydrophobic resins, hydrophilicity imparting agents, composite fibers, films and other molded products Additives for suspension (5) Suspension dispersion stabilizers Paints, ink dispersions, water color, pigment dispersion stabilizers such as adhesives, various vinyl compounds such as vinyl chloride, vinylidene chloride, styrene, (meth) acrylate, vinyl acetate Dispersion stabilizer for turbid polymerization [0035]
(6) Emulsification dispersion stabilizer Ethylenically unsaturated compounds, emulsifiers for emulsion polymerization of butadiene compounds, hydrophobic resins such as polyolefins and polyester resins, post-emulsifiers such as epoxy resins, paraffin and bitumen (7) Various aqueous solutions related to thickeners And emulsion thickeners (8) Coagulant-related suspensions and dissolved flocculants in water, pulp and slurry drainage (9) Soil improver-related (10) Photosensitizer, electrosensitive, photosensitive resist resin (11) Other ion exchange resins, ion exchange resins, ion exchange membranes, chelate exchange resins [0036]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified in the examples, “parts” means “parts by weight”, and “%” means “% by weight”.
[0037]
Example 1
Raw material PVA (saponification degree 99.0 mol%, polymerization degree 1280) was dried at the final step of production, and heat treated at 80 ° C. for 60 minutes to give a degree of swelling of 63 to 1680 μm, a degree of swelling of 3.5, and an elution rate of 12.1. % PVA powder was obtained. Using the PVA powder as a raw material PVA powder, 444 parts were charged in a kneader having an internal volume of 7 liters, 100 parts of acetic acid was put into it, swollen, heated to 60 ° C. while stirring at a rotation speed of 20 rpm, 111 parts of diketene and acetic acid 33 parts of the mixed solution was dropped over 4 hours, and the mixture was further reacted for 30 minutes. After completion of the reaction, the reaction product was washed with 500 parts of methanol and then dried at 70 ° C. for 6 hours to obtain AA-modified PVA having a degree of AA conversion of 8.7 mol% (diketene conversion: 66%). As described above, the AA-modified PVA was extracted from the six types of fractions using the seven types of sieves, and the AA degree was measured. As a result, the AA degree was determined to be 44 to 74 μm: 10.1 mol%, 74 to 105 μm: 9.6 mol%, 105 ˜177 μm: 8.8 mol%, 177-297 μm: 8.6 mol%, 297-500 μm: 7.9 mol%, 500-1680 μm: 7.2 mol%, and AA degree distribution (highest AA degree / lowest The AA degree was 1.4. The following measurements were performed using such AA-PVA.
[0038]
(1) Stability of aqueous solution The viscosity and undissolved content of a 12% aqueous solution of AA-PVA were measured as follows.
(A) A 12% aqueous solution of viscosity AA-PVA was left in a thermostatic bath at 25 ° C. for 1 week, and the viscosity of the aqueous solution before and after being left was measured with a BROOKFIELD MODEL DV-II viscometer (spindle No. 3, 12 rpm). The ratio (1) of the viscosity after standing to the previous viscosity was determined.
[0039]
(B) 100 g of 12% aqueous solution of undissolved AA-PVA is diluted to 600 g with pure water, and 150 g each is divided into four centrifugal sedimentation tubes with an internal volume of 200 ml and centrifuged at 5000 rpm for 30 minutes. The sediment was collected in an evaporating dish with a known weight in advance, and the absolute dry weight of the sediment dried at 105 ° C. for 3 hours was measured.
Undissolved content (%) = (precipitate absolute dry weight (g) / 12) × 100
[0040]
(2) Stability of powder After AA-PVA powder is left in a thermostatic chamber at 60 ° C. for 1 month, a 12% aqueous solution is prepared, and the viscosity of the aqueous solution before and after being left is measured as described above. Asked.
[0041]
(3) Transparency According to JIS K 6726, the transmittance (%) at 430 nm of a 4% aqueous solution of AA-PVA was determined with a spectrophotometer.
The results of (1) to (3) are shown in Table 1.
[0043]
Example 2
In Example 1, 457 parts of raw material PVA powder having a saponification degree of 96 mol%, a polymerization degree of 2000, a swelling degree of 10.1, an elution rate of 18.3%, and a particle size of 105 to 1680 μm was used, and the acetic acid charge was 137 parts. The same operation was carried out except that the amount of diketene charged was 81.8 parts to obtain AA-PVA having an AA degree of 7.2 mol% (diketene conversion: 74%). When the AA-PVA was divided by seven types of sieves as described above, fractions of 105 to 177 μm, 177 to 297 μm, 297 to 500 μm, and 500 to 1680 μm were obtained. When the AA degree of each fraction was measured, 105 to 177 μm: 8.3 mol%, 177 to 297 μm: 7.3 mol%, 297 to 500 μm: 6.8 mol%, 500 to 1680 μm: 6.4 mol% The AA degree distribution (maximum AA degree / lowest AA degree) was 1.3. The obtained AA-PVA was measured in the same manner as in Example 1. The measurement results are shown in Table 1.
[0044]
Example 3
In Example 1, a raw material PVA having a saponification degree of 88 mol%, a polymerization degree of 1700, a swelling degree of 202, an elution rate of 94.5%, and a particle size of 74 to 1680 μm was used, the acetic acid charge was 49 parts, and the diketene charge was The AA-modified PVA having a degree of AA conversion of 4.4 mol% was obtained (diketene conversion rate 87%). As described above, the AA-modified PVA was extracted from the six types of fractions using the seven types of sieves, and the AA degree was measured. As a result, it was determined that 44-74 μm: 5.2 mol%, 74-105 μm: 5.1 mol%, 105 ˜177 μm: 4.8 mol%, 177-297 μm: 4.4 mol%, 297-500 μm: 3.9 mol%, 500-1680 μm: 3.0 mol%, and AA degree distribution (highest AA degree / lowest The AA degree was 1.7. The obtained AA-PVA was measured in the same manner as in Example 1. The measurement results are shown in Table 1.
[0045]
Example 4
In Example 1, 528 parts of raw material PVA having a saponification degree of 80 mol%, a polymerization degree of 500, a swelling degree of 9.5, an elution rate of 14.3%, and a particle size of 44 to 1680 μm was used. The same operation was carried out except that the amount charged was 32 parts, and an AA-modified PVA having an AA degree of 3.2 mol% was obtained (diketene conversion rate: 84%). As described above, the AA-modified PVA was extracted from the six types of fractions using the seven types of sieves, and the AA degree was measured. As a result, it was determined that 44-74 μm: 3.6 mol%, 74-105 μm: 3.4 mol% ˜177 μm: 3.2 mol%, 177-297 μm: 3.2 mol%, 297-500 μm: 3.1 mol%, 500-1680 μm: 3.0 mol%, and AA degree distribution (highest AA degree / lowest The AA degree was 1.2. The obtained AA-PVA was measured in the same manner as in Example 1. The measurement results are shown in Table 1.
[0046]
Comparative Example 1
PVA powder for raw material (saponification degree 99.0 mol%, polymerization degree 1280) PVA powder with swelling degree 0.8 and elution rate 2.7% heat-treated at 105 ° C for 120 minutes when drying in the final step of production The AA-modified PVA having an AA conversion of 5.1 mol% was obtained in the same manner as above (diketene conversion: 39%). As described above, the AA-modified PVA was extracted from the six types of fractions using the seven types of sieves, and the AA degree was measured. As a result, the AA degree was measured. ˜177 μm: 4.5 mol%, 177-297 μm: 3.0 mol%, 297-500 μm: 2.9 mol%, 500-1680 μm: 1.6 mol%, and AA degree distribution (maximum AA degree / lowest The AA degree was 7.1. The obtained AA-PVA was measured in the same manner as in Example 1. The measurement results are shown in Table 1.
[0047]
Comparative Example 2
490 parts of raw material PVA (saponification degree 87.0 mol%, polymerization degree 1700, swelling degree 1.2, elution rate 2.8%, particle size 177 to 1680 μm), acetic acid charge amount 49 parts, diketene The same operation was performed except that the charged amount was 75 parts, and an AA-PVA having an AA conversion of 4.0 mol% was obtained (diketene conversion: 45%). As described above, 6 types of the AA-modified PVA were taken out using 7 types of sieves, and the AA degree was measured. As a result, the AA degree was determined to be 44 to 74 μm: 8.5 mol%, 74 to 105 μm: 7.0 mol% ˜177 μm: 5.0 mol%, 177-297 μm: 2.9 mol%, 297-500 μm: 2.5 mol%, 500-1680 μm: 2.4 mol%, and AA degree distribution (highest AA degree / lowest AA conversion degree) was 3.5. The obtained AA-PVA was measured in the same manner as in Example 1. The measurement results are shown in Table 1.
[0048]
[Table 1]
─────────────────────────────────
Viscosity ratio Undissolved content Transparency
─────────────
Leave in aqueous solution Leave in powder (%) 430nm transmittance (%)
─────────────────────────────────
Example 1 1.03 1.04 0.02 97
Example 2 1.01 1.01 0.01 98
Example 3 1.05 1.04 0.03 96
Example 4 1.00 1.01 0.00 98
─────────────────────────────────
Comparative Example 1 2.24 2.71 0.44 54
Comparative Example 2 1.89 2.02 0.21 62
─────────────────────────────────
[0049]
【The invention's effect】
Since the AA-PVA of the present invention has a specific AA degree distribution, it has high transparency when made into an aqueous solution, has little undissolved content, and has little viscosity change even when stored in an aqueous solution for a long period of time. Also, when the powder is stored for a long period of time and then converted into an aqueous solution, the change in viscosity is small compared to when the powder just after manufacture is converted into an aqueous solution. Further, when the raw material PVA having a specific degree of swelling, dissolution rate, and particle size is reacted with diketene, the AA-PVA of the present invention can be produced efficiently.

Claims (4)

  44 to 74, 74 to 105, 105 to 177, 177 to 297, 297 to 500, 500 to 1680 μm, the degree of acetoacetate esterification of each acetoacetate group-containing polyvinyl alcohol resin fractionated into particle sizes of Calculated from the alkali consumption by neutralization titration, the value obtained by dividing the highest degree of acetoacetic esterification by the lowest degree of acetoacetate esterification is 3.0 to 1.0, containing acetoacetate groups Polyvinyl alcohol resin. The acetoacetate group-containing polyvinyl alcohol resin satisfying the following formulas (1) and (2) is reacted with diketene in producing the acetoacetate group-containing polyvinyl alcohol resin according to claim 1 A method for producing a polyvinyl alcohol resin.
(1) Swelling degree = (A−B) /B≧1.0
(2) Elution rate (%) = (C / 30) × 100 ≧ 3.0
A: Add 270 g of water to 30 g of polyvinyl alcohol resin, leave it at 25 ° C. for 24 hours, filter with suction at a vacuum of 100 mmHg for 10 minutes, and remain on the filter paper (No. 2). Resin weight (g)
B: Weight (g) when the polyvinyl alcohol resin swollen with water was dried at 105 ° C. for 3 hours to obtain a constant weight.
C: 270 g of water was added to 30 g of polyvinyl alcohol resin, left at 25 ° C. for 24 hours, filtered with suction at a vacuum of 100 mmHg for 10 minutes, and water and volatile components were removed from the filtrate obtained using the above filter paper. Weight of non-volatile component when distilled off (g)   The method for producing an acetoacetate group-containing polyvinyl alcohol resin according to claim 2, wherein the degree of swelling of the polyvinyl alcohol resin is 1.0 to 500 and the elution rate is 3.0 to 97.0%. .   The method for producing a polyvinyl alcohol resin containing an acetoacetate group according to any one of claims 2 and 3, wherein the polyvinyl alcohol resin to be reacted with diketene has a particle size of 20 to 5000 µm.