JPH0284450A - Polymer composition - Google Patents

Abstract

PURPOSE:To provide a polymer composition composed of starch and a specific polyvinyl alcohol polymer, having extremely good compatibility and giving an aqueous solution having excellent transparency and shelf stability, stable viscosity with time and good film-forming property. CONSTITUTION:The objective polymer composition having excellent compatibility can be produced by mixing (A) starch such as wheat starch and corn starch, decomposition product of starch, starch derivative, etc., and (B) a polyvinyl alcohol polymer produced by hydrolysis or alcoholysis of a polyvinyl ester (preferably a homopolymer or a copolymer of a 1-25C (more preferably 1-20C) fatty acid vinyl ester or copolymer of the ester with other ethylenic unsaturated monomer) with an acid catalyst and having a saponification degree of preferably 50-99mol%, more preferably 60-99mol%. The weight ratio of A:B is 100:1-1:100, preferably 100:5-5:100.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention is directed to highly compatible starch (a) and a polyvinyl alcohol polymer (b) obtained by acid-catalyzed hydrolysis or alcoholysis of polyvinyl ester. This paper is about good polymer compositions.

[3 Conventional technology A mixture of polyvinyl alcohol (hereinafter abbreviated as PVA) and starch is used as a warp sizing agent for textiles and for paper processing because it is water-soluble, has good film-forming ability, and starch is inexpensive. It is used as a drug. However, PVA and starch are both polymeric compounds and have insufficient compatibility, and tend to separate. Further, the film obtained from the mixed aqueous solution has poor transparency and the physical properties of the film are also unsatisfactory.

In order to improve the compatibility between PVA and starch, various modified starches such as starch derivatives such as etherified starch, esterified starch, and cationized starch, and starch decomposition products such as oxidized starch and dextrin are used as starch. This has been widely attempted. However, starch derivatives increase costs, and the starch decomposition products have a smaller molecular field than the original starch, so PVA
Although the stability of an aqueous solution mixed with starch is improved, the physical properties of the film made from this aqueous solution are not sufficient, and it is even seen to give results inferior to those of starch itself. As described above, even if starch derivatives or starch decomposition products are used, their compatibility with PVA is not sufficient.

On the other hand, it is known that the use of modified PVA copolymerized with long-chain alkyl groups having 4 to 20 carbon atoms improves the compatibility with starch (Japanese Patent Application Laid-Open No. 14544/1983), but the physical properties of the film etc. This is still not completely satisfactory.

Recently, there has also been a proposal (Japanese Patent Application Laid-Open No. 62-21118643) that the compatibility is improved by using PVA having a long chain alkyl group with 4 to 50 carbon atoms at the end, but in this case, the production of the PVA It is economically disadvantageous because it requires expensive long-chain alkyl mercaptan.

Problems to be Solved by Invention C Raw starch is water-soluble, inexpensive, and easy to handle, but because it is a natural product, it suffers from poor quality stability. On the other hand, PVA
is a water-soluble synthetic polymer compound that can be obtained from many brands of stable quality and is used in many fields due to its excellent film-forming ability. However, since it is a synthetic polymer, starch It has the disadvantage of being more expensive than. This 14
Although the use of a mixture of the two is being considered, the two are essentially not sufficiently compatible, and there are various problems in handling such as poor stability and separation, and increase in viscosity over time. i
do. Furthermore, the physical properties of molded products produced from these mixed aqueous solutions are not satisfactory.

l) Means for solving the problems In view of the above situation, we have conducted extensive studies to solve the above problems, and as a result, we have developed a PVA-based polymer ( It has very good compatibility with b), and a mixed aqueous solution of the two has improved stability, the viscosity of the solution changes little over time, and the film produced has excellent transparency and good film properties. This discovery led to the completion of the present invention.

Specifically, the present invention provides a highly compatible polymer composition characterized by comprising starch (a) and a PVA-based polymer (b) obtained by acid-catalyzed hydrolysis or alcoholysis of polyvinyl ester. The aim is to provide a solution to the above-mentioned problems.

The present invention will be explained in detail below.

First, the PVA-based polymer (b) used in the present invention is produced by acid-catalyzed hydrolysis or alcoholysis of polyvinyl ester. The polyvinyl ester in the present invention includes homopolymers of vinyl esters, copolymers of vinyl esters, and copolymers of vinyl esters and other ethylenically unsaturated monomers. As the vinyl ester, vinyl esters of fatty acids having 1 to 25 carbon atoms are preferred, and vinyl esters of fatty acids having 1 to 20 carbon atoms are more preferred. For vinyl esters of fatty acids having more than 25 carbon atoms, '?
The hydrophobicity of the PVA-based polymer produced is too strong, resulting in poor water solubility of the polymer itself, resulting in poor compatibility with starch, making it impossible to achieve the object of the present invention.

There are no particular restrictions on the ethylenically unsaturated monomers as long as they can be co- and R-combined with vinyl esters.
The monomers described in the following publications (April 1, 2013) (Nagano et al.), pages 281-285 and the literature cited therein can be used.

The dust content of the PVA-based IR combination is closely related to the number of carbon atoms of the fatty acid in the residual vinyl ester unit after saponification and the degree of saponification, and is uniquely determined.
Preferably it is 50-3000. The degree of saponification of the PVA-based/R combination is related to the number of carbon atoms in the fatty acid in the residual vinyl ester unit after hydrolysis or alcoholysis of the polyvinyl ester, and generally the higher the number of carbon atoms in the fatty acid, the higher the degree of saponification. Although it can be recognized that a lower degree of saponification is preferable as the number of carbon atoms decreases, in consideration of the characteristics of PVA-based polymers obtained by acid-catalyzed hydrolysis or alcoholysis, the range of 50 to 99 mol% is recommended, 60-99
More preferred is mole %. If it is less than 50 mol%, the hydrophobicity is too strong and the water solubility of the polymer itself becomes poor, resulting in poor compatibility with starch, making it impossible to achieve the object of the present invention. Moreover, if it is more than 99 mol %, the characteristics obtained by hydrolysis or alcoholysis using an acid catalyst cannot be exhibited.

Polyvinyl alcohol polymers obtained by acid-catalyzed hydrolysis or alcoholysis of polyvinyl esters as described above can be produced by several methods described in Japanese Patent Publication No. 37-1495, etc., but industrially Polyvinyl ester-based monomers obtained by polymerizing monomers mainly composed of vinyl esters described in 1iii. an alkyrev group having a carbon number, m and 0 are 0 or an integer of 1 to 6, and m +
n≧2. ] By carrying out the reaction at an elevated reaction temperature in the presence of water in a reaction system using a cyclic polyokine alkylene compound represented by as a solvent and an organic sulfonic acid as a catalyst,
Efficient production with high reaction rate (Patent application 1986-29)
No. 308).

The PVA-based polymer obtained by this method has residual vinyl ester units randomly distributed and has extremely good solubility in water. As a result, the compatibility with starch is remarkably good, the stability of the mixed aqueous solution of both is improved, the change in viscosity of the solution over time is small, and the produced film has excellent transparency and film physical properties are also good. .

On the other hand, as the starch (a) of the present invention, starches obtained from wheat, corn, rice, horse reishiyo, amashiyo, tapioca, sago palm, etc. are used, but - for boat fishing, wheat starch and corn starch are used. Appropriate. It is also possible to use starch decomposition products such as dextrin and oxidized starch, which are produced from the raw starches mentioned above, or starch derivatives such as etherified starch, esterified starch, and cationized starch.

PVA-based polymer (b) obtained by acid-catalyzed hydrolysis or alcoholysis of starch (a) and polyvinyl ester
) is based on weight, (a) : (b) + 0
0.1 to I: 100, more preferably (a
):(b)=lOO:5-5:IoO. If the main purpose is to improve the storage stability of the starch aqueous solution, starch (a) 1
It is appropriate that (b) be used in an amount of at least 1 part by weight, more preferably at least 5 parts by weight, per 00 parts by weight. Starch (a) 100
If the amount of (b) is less than 1 part by weight based on the weight of A part, the effect of adding (b) will not be noticeable. On the other hand, the quality of starch film J,
If the main purpose is starch (a), (
b) is IO parts by weight or more, more preferably 20 parts by weight
or more is suitable. On the other hand, PVA polymer (b) 10
If starch (a) is less than 1 part by weight compared to 0 parts by part by weight, (b)
It is no different from its physical properties.

The starch (a) and the PVA-based polymer (b) used in the present invention can be mixed by mixing both sides with powder and then adding water or putting it in water to gelatinize it, or (a) and A lazy method such as gelatinizing and (b) separately and then mixing them is often adopted, but the PVA-based polymer used in the present invention has extremely good solubility in water, and other PVA-based polymers Efficient dissolution is possible in a shorter time than with polymers. The mixture of the two contains plasticizers, colorants, fillers, salts, boric acid or borax,
Other water-soluble polymers, surfactants, and other additives can also be added.

■ε Actions and Effects of the Invention The polymer composition of the present invention comprising starch (a) and a PVA polymer (b) obtained by acid-catalyzed hydrolysis or alcoholysis of polyvinyl ester has the following characteristics.

That is, the aqueous solution of the composition of the present invention has higher transparency, better storage stability, and lower viscosity than an aqueous solution of a mixture of starch and PVA obtained by ordinary alkali saponification. It has very little change over time and is easy to handle. This is presumed to be because the starch and the 1) VA-based polymer of the present invention have very good compatibility, so that the starch does not aggregate in the aqueous solution and is uniformly dispersed.

Part of the unique interaction between the PVA polymer (b) and starch (a) used in the present invention is inferred from the behavior of the mixed aqueous solution of (b) and (a) with respect to the viscosity.

For example, a PVA-based polymer (polymerization degree 300, saponification degree 96 mol%) obtained by hydrolysis of polyvinyl caprylate in a nooxane solvent using a p-toluenesulfonic acid catalyst is mixed with cornstarch in various proportions, The mixture was heated and dissolved at 95° C. with stirring to prepare an aqueous solution having a solid content concentration of 5% by weight, and the viscosity of the aqueous solution at 20° C. was measured (B-type viscometer).

For comparison, a PVA-based polymer obtained by an alkaline saponification method of polyvinyl acetate (polymerization degree 5501 saponification degree 98.
5 mol %) was similarly mixed and dissolved with corn starch, and the viscosity behavior was investigated.

As a result, in the case of the latter, the viscosity tends to decrease as the content of the PVA-based polymer increases, whereas in the case of the latter, the viscosity of the aqueous solution is generally higher than that of the latter, and the viscosity of the latter shows a tendency to decrease due to hydrolysis using an acid catalyst. Until the proportion of the obtained PVA-based polymer in the composition exceeds 30%, there is almost no decrease in solution viscosity, and there is even a tendency for the viscosity to increase slightly. It was suggested. In addition, in the mixed aqueous solution, the PVA polymer used in the present invention has an appropriate balance between hydrophobic parts and hydrophilic parts.
The VA polymer and starch dissolve well in each other, and as a result, the stability of the mixed aqueous solution is improved, and gelation can be prevented even during long-term storage.

The film formed from an aqueous solution of the polymer composition of the present invention is very homogeneous and has good transparency. Still other PVA
Compared to a mixture of polymer and starch, the film has higher strength and elongation, and exhibits excellent film properties. It is presumed that these are also due to the good affinity between the PVA-based polymer used in the present invention and starch for the above-mentioned reasons.

The polymer composition of the present invention is suitably used as a fiber sizing agent, particularly a warp sizing agent, a paper processing agent, an adhesive, a film forming agent, and the like.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited in any way by the Examples.

As a reference example, PV produced by acid hydrolysis using p-toluenesulfonic acid catalyst in dioxane solvent
An example of the method for producing the A-based polymer is shown below.

Reference Example Polyvinyl acetate (polymerization degree 1750, From now on P V
A c) 60 g (070 mol in terms of ester residue in PVA c) and 1,4-nooxane 18
After charging 0 mc and sufficiently purging the reaction system with nitrogen gas, the temperature was raised to an internal temperature of 80° C., and PVAc was dissolved under stirring.

After dissolving PVAc, 14 g of p-toluenesulfonic acid monohydrate (0,0
A solution prepared by dissolving 50 g (2.78 mol) of 74 mol) in water was added all at once, and the mixture was left standing to raise the internal temperature to 100°C (gauge pressure 0.7 kg/cm').

After confirming that the internal temperature is constant at 100℃, 500rpf
Stirring was started at a stirring speed of fi to carry out the saponification reaction. The reaction solution was a transparent, viscous, homogeneous solution (111 colors). Twenty minutes after the start of the reaction, precipitation of polyvinyl alcohol (hereinafter abbreviated as PVA) was observed from the reaction system, but stirring was continued for 60 minutes. The reaction was carried out.Then, stirring was stopped, and after the reaction mixture was cooled, the precipitated PVA was separated and recovered from the reaction mixture.

The recovered PVA was white and no coloration was observed.

The produced PVA was cut into small pieces, washed with 1,4-nooxane, and dried under reduced pressure in a water bath at 40°C. As a result of measuring the degree of saponification of the dried PVA using a titration method, the degree of saponification was 97 mol%.

After the reaction was completed, the solution portion was clear and colorless, and analysis using gas chromatography confirmed that acetic acid had been quantitatively produced.

Example 1 Polyvinyl caprylate was hydrolyzed in the presence of water using a p-toluenesulfonic acid catalyst in a dioxane solvent according to the method of the reference example, and a PVA-based polymer (polymerization degree 300, A saponification degree of 96 mol%) was obtained. The PVA-based polymer was mixed with corn starch in various proportions, and the mixture was heated at 120°C.
The mixture was heated and dissolved in an autoclave for 1 hour to prepare aqueous solutions with solid content concentrations of 5% and different mixing ratios of PVA polymer and cornstarch. The viscosity of these aqueous solutions at 20°C was measured. The results are summarized in Table 1.

For comparison, a PVA-based polymer obtained by an alkaline saponification method of polyvinyl acetate (polymerization degree 550, saponification degree 98.
5 mol %) was similarly mixed and dissolved with cornstarch in various proportions to prepare an aqueous solution with a solid content concentration of 5%. The measurement results of the viscosity of these aqueous solutions at 20°C are also shown together (Comparative Example 1).

Table 1 [Note: Viscosity of corn starch only, 890 cp (20
℃)] Example 2 Vinyl polybrobionoate was hydrolyzed in dioxane in the presence of water using a benzenesulfonic acid catalyst according to the method of the reference example, and a PVA-based polymer (IRF polymerization degree and dust content of 0) was obtained. , saponification degree of 82 mol%) was obtained. The pvA polymer and wheat starch were mixed in various proportions, heated and dissolved in an autoclave at 120°C for 1 hour, and PvA polymer was dissolved at a solid content of 4%.
Three types of aqueous solutions with different mixing ratios of VA polymer and wheat starch were prepared. The viscosity of these aqueous solutions at 20°C was measured, and then stored at 20°C for one week, and changes in the state and viscosity of the aqueous solutions were observed. The results are summarized in Table 2.

For comparison, a PVA-based polymer obtained by an alkaline saponification method of polyvinyl acetate (polymerization degree 550, saponification degree 985) was used.
mole%) was mixed and dissolved with wheat starch in the same manner, and the solid content concentration was 4.
% aqueous solution was prepared as 'J8' and the same study was carried out (Comparative Example 2).

The following is a margin table. 2 Films were formed using Muto. The film was heated at 20°C, 65% R1-(F
After one week at J4/, Il, the strength and elongation of the film and transmittance were measured. Similar operations were performed on a PVA-based polymer (degree of polymerization 550, saponification Ii'9s, s mol %) obtained by an alkaline saponification method of polyvinyl acetate, and a comparative study was conducted (Comparative Example 3). The results are summarized in Table 3.

Table 3 Example 3 Polyvinyl pronoate was hydrolyzed in a nooxane solvent using a p-toluenesulfonic acid catalyst in the presence of water in accordance with the method of the reference example, and a PVA-based polymer (polymerized degree 5
00, degree of saponification 93 mol%) is i ¥1. Obtained PV
Polymer A was dissolved in hot water to prepare an aqueous solution with a concentration of 10%. Corn starch was also gelatinized by heating at 120° C. for 1 hour to prepare an aqueous solution with a concentration of 10%. After mixing the two solutions in various proportions, drying was set at 70°C. Measurement of physical properties of the film: Shima ITt Autograph DCS-100 model (Crystal Seisakusho)
use.

Sample Width 151Ml11, Thickness approx. 60μm, Measurement length 50
1m111, tensile speed 500nm/min.

Transmittance measurement: Using a Hitachi spectrophotometer (Hitachi).

Wavelength 650nm, Blank: film of alkali saponified PvA polymer.

Examples 4 to 8 Types of vinyl esters constituting polyvinyl esters,
degree of saponification after acid-catalyzed hydrolysis or alfurisis;
PVA-based polymers with various degrees of polymerization were produced by a method similar to the reference example. A mixture of these PVA-based polymers and Co-7 starch at a ratio of 1.1 (weight ratio) was heated and dissolved in hot water at 95° C. for 2 hours to prepare an aqueous solution with a solid content concentration of 5%.

The viscosity of this aqueous solution at 20° C. was measured after dissolution and after 2 days had passed, to examine the stability of the solution. The results are summarized in Table 4.

A PVA-based polymer (degree of polymerization: 1750, degree of saponification: 985 mol%) obtained by an alkaline saponification method of polyvinyl acetate was subjected to the same operation and comparatively studied (Comparative Example 4).

(1) Polyvinyl acetate modified with 4 mol% itaconic acid.

(2) PVA-based polymer produced by an alkali saponification method.

Claims (3)

[Claims] (1) A polymer composition comprising starch (a) and a polyvinyl alcohol polymer (b) obtained by acid-catalyzed hydrolysis or alcoholysis of polyvinyl ester. (2) The vinyl ester constituting the polyvinyl ester is a vinyl ester consisting of a fatty acid having 1 to 25 carbon atoms, and the degree of saponification of the resulting polyvinyl alcohol polymer (b) is 50 to 99 mol% ( 1) The polymer composition according to item 1). (3) The weight mixing ratio of (a) and (b) is 100:1 to 1
:100.