JP2007277492A - Method for producing acetoacetylated polyvinyl alcohol-based resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing a high-quality acetoacetylated polyvinyl alcohol (PVA)-based resin providing an aqueous solution having high transparency and containing little undissolved material when dissolved in water. <P>SOLUTION: The method for producing the acetoacetylated polyvinyl alcohol-based resin by reacting a polyvinyl alcohol-based resin with a diketene in the presence of an organic acid involves carrying out the reaction in the presence of 0.5-10 wt.% water based on the polyvinyl alcohol-based resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an acetoacetylated polyvinyl alcohol (hereinafter referred to as AA-PVA) resin, and more specifically, production of an AA-PVA resin that can stably produce a high-quality product. It is about the method.

  AA-PVA-based resin can be used as a surface-treating agent having good water resistance against ordinary polyvinyl alcohol (hereinafter referred to as PVA) -based resin by reacting with a crosslinking agent. Widely used as an agent.

  As a method for producing an AA-PVA-based resin, a method is known in which PVA-based resin powder is reacted with diketene in the presence of acetic acid to acetoacetylate (hereinafter referred to as AA) (for example, Patent Documents). 1-3).

  However, when an AA-PVA-based resin is produced by this method, the distribution of the degree of modification becomes wide depending on the reaction conditions. Therefore, when the AA-PVA-based resin is dissolved in water, the transparency of the aqueous solution decreases or is soluble. There were problems such as lowering.

JP-A-55-94904 JP-A-55-137107 JP-A-57-40508

  An object of the present invention is to provide a method capable of stably producing a high-quality AA-PVA-based resin in which an impurity component does not elute when dissolved in water and the dissolved aqueous solution has high transparency.

  Therefore, as a result of repeated detailed studies by the present inventors, there is no insoluble matter when dissolved in water by the presence of a small amount of water during the AA reaction, and the transparency of the aqueous solution is also good. The inventors have found that an AA-PVA-based resin can be stably obtained, and have completed the present invention.

That is, the gist of the present invention is a method for producing an AA-PVA-based resin in which a PVA-based resin particle is reacted with diketene in the presence of an organic acid.
It exists in the manufacturing method of AA-ized PVA-type resin characterized by making 0.5-10 weight% of water exist in a reaction system with respect to PVA-type resin.

  In the present invention, by reacting the PVA resin and diketene in the presence of a specific amount of water with respect to the PVA resin, there is no insoluble matter when dissolved in water, and the transparency of the aqueous solution is also improved. A good AA-PVA-based resin can always be produced stably.

  Hereinafter, the present invention will be described in detail.

  A method for producing an AA-PVA-based resin in which a PVA-based resin particle and a diketene that are premised in the present invention are reacted in the presence of an organic acid is known, and the method and conditions are not particularly limited.

  As the PVA-based resin used in the present invention, a resin obtained by saponifying polyvinyl acetate obtained by polymerization of vinyl acetate with an alkali or an acid is usually used. Moreover, what saponified the polymer which copolymerized the monomer copolymerizable with vinyl acetate may be used. Further, the polymer after polymerization may be modified by introducing, for example, an anionic group such as carboxylic acid, sulfonic acid, phosphoric acid, a cation group containing a quaternary ammonium group, a diacetone acrylamide group, a mercapto group, or a silanol group. .

  Examples of monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof, ethylene, Α-olefin such as propylene, olefin sulfonic acid such as (meth) acryl sulfonic acid, ethylene sulfonic acid, sulfonic acid malate, (meth) allyl sulfonic acid soda, ethylene sulfonic acid soda, sulfonic acid soda (meth) acrylate, sulfonic acid Olefin sulfonic acid alkali salts such as soda (monoalkyl malate) and disulfonic acid soda alkyl malate, amide group-containing monomers such as N-methylol acrylamide and acrylamide alkyl sulfonic acid alkali salts, N-vinylpyrrolidone, N- Vinylpyrrolidone induction And the like.

  The degree of saponification of the PVA resin is not particularly limited, but is usually 90 to 100 mol%, preferably 95.0 to 99.8 mol%. Moreover, the polymerization degree of PVA-type resin is 200-4000 normally, Preferably it is 300-3500.

  The average particle size of the PVA-based resin particles is preferably 100 to 500 μm, more preferably 200 to 400 μm. In this range, a good reaction with diketene can be performed.

  As the PVA-based resin particles used in the production method of the present invention, a powder obtained by drying the PVA-based resin obtained by the above-described polymerization and saponification is usually used, but drying in the PVA-based resin manufacturing process is used. The previous solvent-containing PVA-based resin particles can also be used.

  The PVA-based resin particles as described above are reacted with diketene, but the amount of diketene used is determined by the target degree of AA conversion, and is usually 1.0 of the theoretical amount necessary for the target degree of AA conversion. It is -5.0 mol times. The target AA degree is usually 0.01 to 10 mol%, preferably 0.03 to 8 mol%.

  The AA reaction is usually carried out by spraying diketene in an inert gas atmosphere at 20 to 120 ° C. while stirring or fluidizing the PVA resin particles. In the AA reaction, from the viewpoint of reaction efficiency, for example, the reaction is carried out in the presence of a small amount of a basic compound such as sodium acetate, potassium acetate, primary amine, secondary amine, tertiary amine, particularly sodium acetate. It is desirable.

  The amount of the catalyst is usually 0.1 to 1% by weight with respect to the PVA resin particles.

  In addition, since the PVA resin particles obtained by the above polymerization and saponification usually contain a small amount of sodium acetate, in that case, sodium acetate contained in the PVA resin particles Acts as a catalyst, so there is no need to add a separate catalyst.

  The reaction apparatus used for the AA reaction is not particularly limited as long as it can be heated and stirred, and examples thereof include a kneader, a Henschel mixer, various other blenders, and a stirring dryer. Can do.

  In the reaction of the PVA resin particles and diketene in the present invention, an organic acid is present, and the organic acid is usually an organic acid having 1 to 4 carbon atoms such as acetic acid, propionic acid, butyric acid, and isobutyric acid. Among them, acetic acid is preferable from the viewpoint of affinity with the PVA resin.

  The addition amount of the organic acid is usually 0.1 to 50% by weight, preferably 0.5 to 30% by weight, based on the PVA resin. The presence of the organic acid swells the PVA-based resin powder and can perform a good AA reaction.

  The method of blending an organic acid into a PVA resin is usually carried out by previously contacting a PVA resin particle with an organic acid, and typically the organic acid is stirred with respect to the PVA resin particle. Below, it is carried out by a spraying method. Moreover, the method of immersing a PVA-type resin granular material in an organic acid may be used.

  After contacting the organic acid and the PVA resin, for example, the organic acid penetrates into the PVA resin by leaving it at 0 to 90 ° C., preferably 10 to 80 ° C. for 10 minutes or more, preferably 20 minutes or more. In addition, the PVA resin is in a swollen state, and the reaction efficiency with diketene is improved, which is preferable.

  In the present invention, it is an essential requirement that the AA reaction is performed in the presence of 0.5 to 10% by weight of water with respect to the PVA resin. That is, even when the reaction conditions vary due to the presence of this small amount of water, a high-quality AA-PVA-based resin having no insoluble matter when dissolved in water and having good transparency of the aqueous solution is obtained. It can be manufactured stably. Since the diketene used in the present invention is immediately decomposed by contact with water, it has been conventionally considered that the water during the AA reaction needs to be reduced as much as possible. However, the present invention dares to use a small amount of water. Is to actively exist.

  The usage-amount of water is 0.5-10 weight% with respect to PVA-type resin, Preferably it is 1-5 weight%. If it is less than the lower limit, the effect obtained by adding water tends to be insufficient, and if the upper limit is exceeded, the diketene used for the AA reaction will disappear due to decomposition, which is economically undesirable.

  As a method of blending water, a method of blending water after blending the organic acid into the PVA resin granules, a method of blending the mixture of the organic acid and water into the PVA resin granules, PVA resin Any of the methods of blending the organic acid after blending water into the powder may be used, but the method of blending the mixture of the organic acid and water into the PVA resin powder from the operation surface is preferred.

  Moreover, it is preferable to leave the PVA-type resin which mix | blended water normally at 0-90 degreeC, Preferably it is 10-80 degreeC, Preferably it is left for 20 minutes or more. By this standing, water permeates into the PVA resin, the PVA resin becomes swollen, and the reaction efficiency with diketene is further improved.

  As a typical operation method for producing the AA-PVA-based resin of the present invention, usually, a PVA-based resin particle as a raw material is stirred in a reactor capable of stirring, and a predetermined amount of acetic acid and a predetermined amount of The AA reaction can be completed by spraying water sequentially or simultaneously and spraying a predetermined amount of diketene with stirring for a certain period of time and reacting for a certain period of time. After the reaction, the AA-converted PVA-based resin particle is then mixed with an excessive amount of alcohol such as methanol or water, in particular alcohol, in accordance with a conventional method, and after decomposition of the remaining unreacted diketene, if necessary. Then, it is washed with a washing solvent such as alcohol such as methanol, and further dried to recover the product as a product.

  The AA-PVA-based resin obtained by the production method of the present invention is used for the production of gel bodies, photographic photosensitive materials, chelate exchange resins, molding materials, paper strength enhancers, various paper overcoat agents, and emulsifiers. It can be used suitably.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.

<Measurement method of insoluble matter>
A 500 mL Erlenmeyer flask set in a water bath was charged with 400 mL of deionized water, 20 g of AA-PVA resin was added with stirring, the temperature of the aqueous solution was adjusted to 95 ° C., and the mixture was stirred at the same temperature for 1 hour.

  A pre-weighed wire mesh (A (g), mesh: 44 μm) was set in a filtration device, and the heated and stirred aqueous solution was gradually poured onto the wire mesh and filtered. About 2 L of warm water (80 to 90 ° C.) was used to completely transfer the insoluble matter in the Erlenmeyer flask to a wire mesh and wash it.

  The filtered wire mesh was dried with an electric constant temperature dryer at 105 ± 2 ° C. for 2 hours. The wire mesh was taken out from the dryer and cooled with a desiccator for 15 minutes, and then the wire mesh was weighed (B (g)). The insoluble rate was calculated by the following formula.

Insoluble rate (%) = (B−A) / S × 100
A: Wire mesh weight (g)
B: Weight of wire mesh after drying insoluble matter (g)
S: Weight of sample (g)

<Measurement method of aqueous solution transparency>
An aqueous solution of PVA resin having a concentration of 5% was prepared by a temperature raising method (attainment temperature 95 ° C.). The obtained aqueous solution was cooled to room temperature, and the concentration of the aqueous solution was measured and adjusted to 4.0%. The temperature was adjusted in a constant temperature water bath set at 30.0 ° C., and the transparency (transmittance) was measured with a spectrophotometer (wavelength 430 nm, quartz cell 2 cm).

Example 1
Into a ribbon blender with a temperature controller, 100 parts by weight of PVA powder (saponification degree 98 mol%, polymerization degree 2400, average particle diameter 400 μm) containing 0.5% sodium acetate was charged so that the PVA powder was 80 ° C. The jacket set temperature was 90 ° C., and the mixture was stirred at 35 rpm. After the PVA powder reaches 80 ° C., 2 liquid parts of ion-exchanged water (2% by weight with respect to the PVA powder) and 30 parts by weight of acetic acid (30% by weight with respect to the PVA powder) are mixed with stirring. Added over time. After completion of the addition, the mixture was stirred for 1 hour under the same conditions.

  The jacket set temperature is 40 ° C. so that the PVA powder becomes 60 ° C., and after the PVA powder becomes 60 ° C., 19.3 parts by weight of diketene (19.3 wt% relative to PVA) is added over 4 hours 30 minutes. Spray added. After completion of the diketene addition, the PVA powder was stirred for 30 minutes while the temperature was 60 ° C.

After completion of the reaction, 300 parts by weight of methanol was added to decompose the residual diketene. Then, after solid-liquid separation, the PVA was washed twice with methanol at an extractant ratio of 3 (times), and dried with a drier set at 60 ° C., and the AA conversion degree was 4.2 mol%. A PVA resin was obtained.
The evaluation results are shown in Table 1.

Example 2
The same procedure as in Example 1 was performed except that the amount of water added was changed to 1 part by weight (1% by weight relative to PVA) and diketene was changed to 18.2 parts by weight (18.2% by weight relative to PVA). An AA-PVA resin having an AA degree of 4.2 mol% was obtained.
The evaluation results are shown in Table 1.

Comparative Example 1
AA conversion with an AA degree of 4.3 mol% was carried out in the same manner as in Example 1 except that water was not added and 16.3 parts by weight of diketene (16.3% by weight based on PVA) was used. A PVA resin was obtained.
The evaluation results are shown in Table 1.

Claims (3)

In the production method of acetoacetylated polyvinyl alcohol resin in which polyvinyl alcohol resin granules are reacted with diketene in the presence of organic acid,
A method for producing an acetoacetylated polyvinyl alcohol resin, characterized in that 0.5 to 10% by weight of water is present in the reaction system with respect to the polyvinyl alcohol resin. The method for producing an acetoacetylated polyvinyl alcohol resin according to claim 1, wherein a mixture of an organic acid and water is added to the polyvinyl alcohol resin, and then the polyvinyl alcohol resin and diketene are reacted. The method for producing an acetoacetylated polyvinyl alcohol resin according to claim 1 or 2, wherein the organic acid is acetic acid.