JPH01193306A - Production of high-polymerization degree polyvinyl alcohol-based polymer - Google Patents

Abstract

PURPOSE:To obtain the title polymer outstanding in solubility, by dissolving a high-polymerization degree polyvinyl ester-based polymer emulsion in methanol followed by continuously feeding the resultant solution into a methanol bath together with a basic catalyst without unnecessarily removing the water in the system. CONSTITUTION:An emulsion of a high-polymerization degree polyvinyl ester- based polymer with in intrinsic viscosity of >=1.5dl/g (pref. >=3.2dl/g), produced by emulsion polymerization process is mixed with methanol to produced a virtually homogeneous solution. This solution is continuously fed to a methanol bath together with a basic catalyst (e.g., NaOH, potassium methylate) where a saponification is carried out so that the final slurry concentration is 0.2-10 (pref. 0.5-8)wt.%, thus obtaining the objective polymer with an intrinsic viscosity of <=1.5dl/g (pref. >=3.2dl/g) and an average granular size of 16 mesh, excellent in solubility.

Description

DETAILED DESCRIPTION OF THE INVENTION Δ Industrial Field of Application The present invention relates to a method for producing a highly polymerized polyvinyl alcohol (hereinafter abbreviated as PVA) based polymer. For more information,
A highly polymerized polyvinyl ester polymer obtained by emulsion polymerization and having an intrinsic viscosity of 1.5 dρ/g or more, preferably 3.2 dρ/g or more, with an intrinsic viscosity of 1.5 dQ/g or more,
To obtain a polyvinyl alcohol-based polymer with a high degree of polymerization, preferably greater than 3.2 d&/g, a polyvinyl ester-based polymer emulsion is mixed with methanol to obtain a substantially homogeneous solution, and the solution is poured into a methanol bath with a base. A highly soluble polyvinyl alcohol-based polymer characterized by being continuously supplied with a chemical catalyst and saponified so that the final slurry concentration is 0.2% by weight or more and 10% by weight or less. Regarding the manufacturing method.

[Here, the intrinsic viscosity of the polyvinyl ester polymer is defined as the value measured in acetone at 30°C for polyvinyl acetate obtained by saponifying the polyvinyl ester polymer and then re-acetating it. The intrinsic viscosity of a polymer is defined as a value measured in acetone at 30° C. for polyvinyl acetate obtained by reacetylating the polyvinyl alcohol polymer.

B. Conventional technology As one of the few crystalline, water-soluble polymers, PVA-based polymers have excellent interfacial properties and strength properties, making them suitable for paper processing.
It is well known that it is used as a stabilizer for textile processing and emulsions, and also plays an important role as a raw material for vinylon film and fiber.

However, the upper limit of the polymerization degree of conventional PVA-based polymers is 2000 due to processing characteristics and ease of handling, and because it is difficult to obtain a polyvinyl acetate-based raw material with a high degree of polymerization. There are only about 3,000 special items.

On the other hand, rapid advances in processing technology in recent years have made it possible to process polymers in the ultra-high degree of polymerization range, and are now succeeding in bringing out previously unknown physical properties. In the case of PVA-based polymers, physical properties can be improved in conventional applications by increasing the degree of polymerization, but such PVA-based polymers can be obtained by saponifying polyvinyl ester-based polymers, particularly polyvinyl acetate-based polymers. . The outline of the manufacturing process is [Production of polyvinyl acetate polymer - Preparation of methanol solution of polyvinyl acetate polymer - Saponification reaction → PVA
], and as the saponification reaction, a methanol decomposition reaction using a basic catalyst is usually adopted, taking into account the saponification rate, saponification degree control, by-produced salts, and the physical properties of the obtained PVA.

During saponification, the most important issues are the residual monomer and water. The foretone is the key to the coloring of PVA,
The latter causes difficulties such as a decrease in the saponification rate and an increase in the amount of by-product salts due to the increase in the amount of catalyst required.

By the way, the saponification reaction of polyvinyl acetate-based polymers is initiated by adding a basic catalyst to a methanol solution of polyvinyl acetate-based polymers, except in very special cases. This is because the saponification rate and degree of saponification can be controlled only when the catalyst is uniformly distributed throughout, and the desired PVA can be obtained without saponification unevenness. Therefore, if a polymerization method in which the polymer precipitates, such as @turbidity polymerization or emulsion polymerization method, is adopted, once the polyvinyl acetate polymer is taken out, water and unreacted monomers are removed by washing and drying for the reasons mentioned above. After sufficient removal, it will be dissolved in methanol and flowed into the process after saponification. However, it becomes extremely difficult to dissolve polyvinyl acetate-based polymers in methanol due to the increase in molecular weight, and a large amount of time is required for dissolution, which is a major problem.

The present inventors have developed a method that overcomes the disadvantages of post-polymerization processes in emulsion polymerization by directly producing a specific amount of an emulsion with a specific particle size from a polyvinyl ester polymer emulsion without separating or taking out the polymer. A method of obtaining PVA by dissolving it in methanol has already been proposed.

(Japanese Patent Application No. 62-37155) By the way, the general process after the usual saponification reaction is [preparation of methanol solution of polyvinyl acetate polymer - saponification reaction - pulverization - PVA]. In the case of highly dust-containing PVA-based polymers, dissolution in water and organic solvents becomes difficult as the degree of polymerization increases, so in order to obtain highly soluble PVA with a high degree of polymerization, pulverization by pulverization is required. I will depend on it.

Furthermore, a slurry saponification method is known as a method for obtaining a finely powdered PVA polymer without the need for pulverization. However, when obtaining a methanol solution of a polyvinyl ester polymer from the emulsion polymerization method, water is mixed in with conventional polyvinyl ester polymers that do not have a high molecular weight, so a finely powdered PVA polymer is obtained using the slurry saponification method. It is not possible.

Suppose that the intrinsic viscosity obtained by the emulsion polymerization method of the present invention is 1 sdi!/
Existing when producing a highly polymerized polyvinyl alcohol-based polymer having excellent solubility and having an intrinsic viscosity of 1.5 dQ or more and 7 g or more from a high-polymerized polyvinyl ester polymer having an intrinsic viscosity of 1.5 dQ or more, preferably 3.2 dρ/g or more. The aim is to overcome the above-mentioned difficulties and provide a new manufacturing method that can be easily implemented on an industrial scale.

D. A. In one step to solve the problem, the present inventors found that the intrinsic viscosity obtained by the emulsion polymerization method was 1.5.
dρ/g or more, preferably 3.2di! /g, the intrinsic viscosity is 1 from a high polymerization degree polyvinyl ester polymer.
．． As a result of intensive studies on methods for producing polyvinyl alcohol-based polymers with a high polymerization degree of 5 dc/g or more, preferably 3.2 di2/g or more, we found that coagulating an emulsion of a polymerized polyvinyl ester polymer and mixing it with methanol to obtain a substantially homogeneous solution without taking out the polymer; continuously feeding the solution together with a basic catalyst into a methanol bath; By saponifying the final slurry to a concentration of 0.2% by weight or more and 10% by weight or less, high polymerization with excellent solubility can be achieved without using any of the complicated technical means described above. The inventors completed the present invention by discovering that PVA-based polymers can be obtained extremely easily.

[Here, the limit degree of the polyvinyl ester polymer is defined as the value measured in acetone at 30°C for polyvinyl acetate obtained by saponifying and reacetylating the polyvinyl ester polymer, and for polyvinyl alcohol The intrinsic viscosity of a polymer is defined as the value of polyvinyl acetate obtained by re-acetating the polyvinyl alcohol-based polymer at 30°C in acetone plus 11.

] The manufacturing method of the present invention will be explained in detail below.

The most important feature of the production method of the present invention is that the highly polymerized polyvinyl ester polymer obtained by emulsion polymerization has an intrinsic viscosity of 1.5 d/g or more, preferably more than 2 dl/g, especially From the polyvinyl acetate polymer emulsion, the intrinsic viscosity as defined above or 1. ．． 5d&
/g or more, preferably more than 3.2 dR/g, the most problematic process in terms of time and energy when obtaining highly polymerized PVA with excellent solubility, that is, the process of pulverization in the case of saponification, In addition, in the case of slurry saponification, the purpose is to obtain PVA with a high degree of polymerization and excellent solubility without going through the process of removing water.

The emulsion obtained by emulsion polymerization method contains water, polymer,
It consists of monomers, stabilizers, etc., and is mixed with methanol (
- After removing unreacted monomers by distillation from the substantially uniform methanol solution obtained, water is present in the methanol solution of the polyvinyl ester polymer.

Ordinary slurry saponification is difficult in a water-containing system, but in the present invention, unexpectedly, a methanol solution containing about 2 times the weight of water relative to the highly polymerized polyvinyl ester polymer is used over a basic catalyst. The final slurry concentration is 0.2% by weight or more and 10% by weight or less, more preferably 0.5% by weight or more and 8% by weight or less. The PVA-based polymer did not aggregate to become "Mamaco J", but was extremely easily turned into a slurry, and was able to be made into high polymerization degree PVA.

The intrinsic viscosity of polyvinyl ester polymer is 1.5 FI
If it is less than Q/g, the PVA-based polymer produced will aggregate and become a "mamako", resulting in a clean slurry state (grinding, etc.), which is not preferable as it requires subsequent treatment such as pulverization.

In addition, if the final slurry concentration is less than 0.2% by weight,
Although there is no problem with the solubility of the highly polymerized polyvinyl alcohol-based polymer, the slurry concentration becomes low, making it difficult to pass through subsequent steps, which is not preferable.

Furthermore, if the final slurry concentration is greater than 10% by weight, the PVA-based polymer produced will aggregate and become "mamako", making it impossible to obtain the desired slurry state.

As described above, in the present invention, a highly polymerized polyvinyl ester polymer emulsion is directly dissolved in methanol, and it is continuously poured into a methanol bath together with a basic catalyst without removing water in the system more than necessary. It is characterized by supplying it to a polyvinyl alcohol-based polymer with excellent solubility, and there are no particular restrictions on the properties of the emulsion used, but from the viewpoint of producing high-quality, high-polymerization PVA,
It is preferable to use a low-molecular-weight surfactant as a stabilizer, that is, a nonionic surfactant, a nonionic-anionic surfactant, or an anionic surfactant, and the polymerization rate of the vinyl ester is preferably 95% or less, preferably It is 90% or less, more preferably 80% or less.

In addition, polyvinyl ester polymers include vinyl formate,
Vinyl acetate, vinyl propionate, vinyl valerate,
Examples include polymers such as vinyl caprate, vinyl laurate, and vinyl stearate, with vinyl acetate polymers being particularly preferred.

Furthermore, since it is a copolymer obtained by copolymerizing monomers that can be copolymerized with the above-mentioned vinyl ester monomers, examples of these monomers include (meth)acrylic acid, (meth)acrylic acid ester, itaconic acid, Examples thereof include esters thereof, maleic acid esters or maleic anhydrides, (meth)acrylamide or derivatives thereof, vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, acrylonitrile, vinylalkoxysilane, and the like.

The production method of the present invention can be applied to the production of high polymerization degree PVA polymers having an intrinsic viscosity of 1.5 d (!/g or more), but in particular, it can be applied to the production of high polymerization degree PVA polymers from high polymerization degree polyvinyl ester polymer emulsions. It is effective when obtaining PVA with a high degree of polymerization having an intrinsic viscosity of more than 3.2 dg/g.

In addition, when obtaining PVA with a high degree of polymerization in this way, it is desirable that the polyvinyl ester polymer emulsion be one obtained by emulsion polymerization in a mixed medium of water and methanol. It is desirable that the mixing ratio of water and methanol be approximately equal to each other in terms of weight ratio.

The basic catalyst used in the present invention includes sodium hydroxide, potassium hydroxide or sodium methylate,
Examples include potassium methylate and sodium methylate.

Further, in the present invention, the particle size of the highly polymerized PVA powder is 16 mesh or less, more preferably 60 mesh or less.

If it is larger than 16 mesh, it takes time to dissolve, which is not preferable.

81 Actions and Effects of the Invention The present invention has an intrinsic viscosity of 1.5 dρ/
This process is most problematic in terms of time and energy when obtaining highly soluble PVA with an intrinsic viscosity of 1.5 d (!/g or more) from a highly polymerized polyvinyl ester polymer emulsion of 1.5 d (!/g or more). In other words, we provide a manufacturing method for obtaining PVA with a high degree of polymerization with excellent solubility without going through the process of pulverization in the case of normal saponification, or the process of removing water in the case of slurry saponification. A highly polymerized polyvinyl ester polymer emulsion is directly mixed with methanol to obtain a substantially homogeneous solution, and the solution is continuously fed into a methanol bath for basic melting until the final slurry concentration is 0.2. This was achieved by saponification to a weight percent of IO heavy weight or less.

The production method of the present invention is applicable to the production of highly soluble PVA-based polymers with an intrinsic viscosity of 1.5 dC/g or more, but especially those with an intrinsic viscosity of 3.2 dF! It is more effective when obtaining an ultra-high polymerization degree PVA-based polymer with excellent solubility of /g or more.

In addition, PVA-based polymers with a high degree of saponification are normally difficult to dissolve, but since the PVA-based polymer with a high degree of saponification and high degree of polymerization obtained by the production method of the present invention is a porous powder, it is difficult to dissolve. is easy. Particularly when the degree of saponification is 99.9 mol% or more, the effect is remarkable.

In addition, in the present invention, since water from the emulsion is present in the methanol solution, stabilizers, by-product salts, etc.
The presence of water has the effect of washing away impurities brought into the polymer system.

The PVA thus obtained can be used in conventional fields of application, and the highly polymerized PVA effectively obtained in the present invention can be used as a PVA-based high-strength sheet or PV
It is suitably used as an A-based high-strength fiber.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto. In addition, "%" and [part] in the examples are both "% by weight"
and “parts by weight”.

Example 1 300 parts of ion-converted water, 300 parts of vinyl acetate, 100 parts of methanol, and polyethylene ethylene [POE (50)
] 12 parts of nonylphenyl ether (Noniball 500, manufactured by Sanyo Chemical Co., Ltd.), 50.・711,0 to 0.
Weigh out 01 part and Rongalit 023 part 30
After boiling for a minute, it was cooled to -20℃ while introducing nitrogen, and adjusted with separately degassed ion-exchanged water.
% of hydrogen peroxide solution was uniformly and continuously added at a rate of 7 parts/hr, polymerization was started. During polymerization, the system was sealed with nitrogen gas.
Prevents oxygen from entering. After 2.5 hours, when the polymerization rate reached 50%, the addition of hydrogen peroxide was stopped, and then 05% was added.
After stirring for an hour, the polymerization was stopped.

The emulsion obtained here was mixed with 130% methanol at room temperature.
Into a solution of 0.5 parts of hydroquinone monomethyl ether in 0 parts (methanol/polymer=20), it was gradually added and dissolved under stirring to obtain a substantially homogeneous solution.

Thereafter, unreacted vinyl acetate monomer was removed under reduced pressure while adding methanol to obtain a water-containing methanol solution of polyvinyl acetate. (Polymer concentration 7.3%, water concentration 8.8%) Take a part of this solution, concentration 5%, [Na0Il]/[
VAc] (molar ratio) -〇, L saponified at a temperature of 40°C,
0.1 part of the obtained polyvinyl alcohol (PVA) was dissolved in a mixture of 8 parts of acetic anhydride and 2 parts of pyridine at 105°C for 20 minutes.
The intrinsic viscosity of polyvinyl acetate, which was reacetylated with occasional stirring for several hours and repeatedly purified by reprecipitation in an acetone-ether and acetone-water system, was measured at 30°C in acetone, and it was found that [η] = 4.20 ( di!/g).

(Measured by dilution method using an Ubbelohde-type viscosity tube) Next, 200 parts of methanol was charged in advance into a glass reaction vessel equipped with a stirrer and a cooling tube, and the reaction vessel was
It was immersed in a constant temperature bath at 7°C. Next, a water-containing methanol solution of polyvinyl acetate (polymer concentration 5%, water concentration 6%) was prepared.
%) was charged simultaneously with 100 parts of a 7% methanol solution of sodium methylate, and a saponification reaction was carried out continuously over a period of 2 hours. The resulting PVA slurry (final slurry concentration: 1.6%) was filtered using a glass filter, neutralized with acetic acid, and washed twice with 300 parts of methanol.

Then, it was dried in a dryer at 40° C. for 5 hours to obtain PVA as a white fine powder. The degree of saponification was measured and was 997 mol%.
Met. Also. When the degree of occurrence was determined by ff111, all of them were 32 metsuyu or less, and 60%, and polyvinyl acetate was repeatedly purified by reprecipitation in the same manner as above.
When the intrinsic viscosity was measured at 30°C in acetone, [η
] -L20 (d&/g).

Furthermore, when 1 part of this finely powdered highly polymerized PVA with 60 meshes or less and +00 meshes or more and 100 parts of water were heated and stirred at 93°C, the PVA disappeared after 5 minutes and a homogeneous solution was obtained. Similarly, add 2 parts of r'VA and 100 parts of water to 93%
When the mixture was heated and stirred at ℃, a homogeneous solution was obtained after 8 minutes.

Comparative Example 1 Aqueous methanol solution of polyvinyl acetate of Example I (polymer concentration 73%, water concentration 88%, intrinsic viscosity [77]-4
, 20dQ, /g) at 40°C, [Na011] /
[The saponification reaction was carried out under the conditions of VAc co(molar ratio)=O, I5.

The obtained gel-like PVA with an intrinsic viscosity of "η3-4.20 d&/g (measured for re-acetated polyvinyl acetate) was crushed,
After filtration, it was similarly neutralized with acetic acid and washed twice with methanol. Then, it was dried in a dryer at 40° C. for 5 hours to obtain PVA as a white powder. The degree of saponification was measured and was 99.
It was 5 mol%.

Further, when a dissolution test was conducted on this finely powdered highly polymerized PVA having a particle size of 60 mesh or less and 100 mesh or more in the same manner as described in Example 1, it was found that 1 part of PVA and 1 part of water
In the case of 00 parts, it took 10 minutes to dissolve, and in the case of 2 parts of PVA and 100 parts of water, it took 15 minutes to dissolve.

Comparative Example 2 A hydrous methanol solution (polymer concentration 30%, water concentration 10%) of polyvinyl acetate with limit conclusion [η] -〇, 84 dQ, /g was subjected to a saponification reaction in the same manner as described in Example 1. When this was carried out, PVA agglomerated and it was not possible to obtain a PVA slurry.

Comparative Example 3 Intrinsic viscosity obtained by normal anhydrous saponification method [η] = 1.7
0dρ/g, PVA with saponification degree of 99.9mo12%,
A dissolution test was conducted in the same manner as described in Example 1 using finely powdered PVA having a particle size of 60 mesh or less and 100 mesh or more, and it was found that 1 part of PVA and 100 parts of water
In this case, even after 30 minutes, it was not possible to obtain a homogeneous solution.

As described above, the production method of the present invention is extremely effective in producing porous and highly polymerized PVA with excellent solubility.

Patent applicant RiRashi Co., Ltd.

Claims (5)

[Claims] (1) Intrinsic viscosity obtained by emulsion polymerization method is 1.5 dl/g
When obtaining a high polymerization degree polyvinyl alcohol polymer having an intrinsic viscosity of 1.5 dl/g or more from the above high polymerization degree polyvinyl ester polymer, the polyvinyl ester polymer emulsion is mixed with methanol to make it substantially uniform. A dissolving method characterized by obtaining a solution, continuously feeding the solution together with a basic catalyst into a methanol bath, and saponifying the solution so that the final slurry concentration is 0.2% by weight or more and 10% by weight or less. A method for producing a highly polymerized polyvinyl alcohol polymer with excellent properties. [Here, the intrinsic viscosity of the polyvinyl ester polymer is determined by saponifying the polyvinyl ester polymer,
For reacetylated polyvinyl acetate, in acetone, 30
The intrinsic viscosity of polyvinyl alcohol-based polymers is defined as the value measured at °C, and the intrinsic viscosity of polyvinyl alcohol-based polymers is defined as polyvinyl acetate obtained by re-acetating the polyvinyl alcohol-based polymers in acetone.
Defined by the value measured at 0°C. ] (2) The intrinsic viscosity of the polyvinyl ester polymer is 3.2
dl/g or more, the manufacturing method according to claim (1). (3) The manufacturing method according to claim (1), wherein the polyvinyl alcohol polymer obtained has an intrinsic viscosity of more than 3.2 dl/g. (4) Final slurry concentration is 0.5% by weight or more, 8% by weight
The manufacturing method according to claim (1), which is as follows. (5) Claim (1) wherein the obtained highly polymerized polyvinyl alcohol polymer has an average particle size of 16 mesh or less.
).