JPS62288643A - Polymer composition - Google Patents

Abstract

PURPOSE:To provide a polymer composition composed of starch and a specific polyvinyl alcohol polymer, giving a mixed aqueous solution of both components having high storage stability and capable of forming a coating film having excellent transparency and film properties and suitable for warp-sizing agent for textile. CONSTITUTION:(A) Starch (e.g. starch of wheat, corn, rice, etc.) is compounded with (B) a polyvinyl alcohol polymer having 4-50C, preferably 8-24C long-chain alkyl group at the terminal and having a polymerization degree of 10-3,000, preferably 50-2,500. The ratio of A:B is 100:0.5-1:100, preferably 100:5-5:100.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention, 11. The present invention consists of starch and a polyvinyl alcohol polymer having a long chain alkyl group with 4 to 50 carbon atoms at the end. This invention relates to a polymer composition with very good compatibility.

A mixture of strained polyvinyl alcohol (hereinafter abbreviated as PVA) and starch is used as a warp sizing agent for fibers because it is water-soluble and has good film-forming ability, and mame flour is inexpensive. It has been used as a paper processing agent, etc. However, since PVA5'm powder is both a polymer compound, it has poor compatibility, and the mixed aqueous solution of PVA and starch has poor stability and tends to separate quickly, and the film obtained from this same mixed aqueous solution is The transparency is poor, and the physical properties of the film are not very good.

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 may be used as starch. have been widely attempted, but starch derivatives have the disadvantage of high cost;
On the other hand, the V starch degradation product has a smaller molecular weight than the original starch, and therefore the stability of the mixed aqueous solution with PVA is improved.
The physical properties of the film made from this mixed aqueous solution do not change much (
In fact, the results may even be worse. In other words, even if these d derivatives or starch decomposition products are used, their compatibility with PVA is still insufficient.

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 raw starch (Japanese Patent Application Laid-Open No. 14544-1983).
Although the stability of the mixed aqueous solution is certainly improved compared to ordinary PVA, it still tends to gel, and the physical properties of the film produced from the mixed aqueous solution cannot be said to be fully satisfactory. Moreover, the above-mentioned modified starches have no effect. P with a hydrocarbon long chain alkyl group at the end
The manufacturing technology for VA polymers is already known (Japanese Patent Publication No. 1831/1973, Japanese Patent Application Laid-open No. 108207/1983).
, L or (,,:) The technology regarding the compatibility between PVA-based polymers and starch is not yet known.

The Jil'tera raw starch that they are trying to solve is water-soluble, cheap, and easy to obtain.
On the other hand, PVA is a water-soluble synthetic polymer compound with stable quality, and there are many brands and it is used in many fields due to its excellent film-forming ability. Therefore, it has the disadvantage of being more expensive than starch.

For this reason, a mixture of PVA and starch is used, which has physical properties intermediate between the two. However, since these two substances essentially have poor compatibility, the stability of the mixed aqueous solution is also poor (J). Furthermore, the physical properties of molded products produced from these mixed aqueous solutions are also not satisfactory.

As a result of intensive studies under such circumstances, the present inventor found that P
VA-based polymers and starch have very good compatibility, and the stability of a mixed aqueous solution of the two is improved, the viscosity of the mixed aqueous solution changes little over time, and the film made from this mixed aqueous solution has good transparency. The inventors have completed the present invention by discovering that the film has excellent properties and good physical properties.

A terminal hydrophobic group-modified PVA polymer having a long chain alkyl group having 4 to 50 carbon atoms at the terminal end that can be used in the present invention will be explained. The long chain alkyl group at the end has 4 to 5 carbon atoms.
A value of 0 is appropriate. If the number of carbon atoms is less than 4, unmodified P
It is not much different from VA and has poor compatibility with starch. In addition, polymers with carbon numbers exceeding 50 are too hydrophobic and have poor water solubility, resulting in poor compatibility with starch and cannot achieve the purpose of the present invention. is suitable, but preferably one having 8 to 24 carbon atoms. Examples of such groups include straight-chain alkyl groups, branched alkyl groups, and alkylaryl groups having 4 to 50 carbon atoms, and those having a linking group composed of atoms such as 0, N, and S. Also included.

Next, the degree of polymerization of the polymer is closely related to the amount of terminal groups introduced, but is 10 to 30,000, preferably 50 to 250.
0 is appropriate. There are no particular restrictions on the degree of saponification, but it is usually 50 mol% or more, preferably 7
It is 0 mol% or more.

The polymer may also contain small amounts of units in addition to vinyl alcohol units and residual vinyl ester units such as vinyl acetate; examples of these include α-olefins such as ethylene, propylene, and isobutyne; Acid, unsaturated acids such as methacrylic acid, crotonic acid, maleic acid, itaconic acid, maleic anhydride or their salts or alkyl esters, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, alkyl vinyl ether, N,N-dimethylacrylamide , N-
Examples include vinylpyrrolidone, vinyl chloride, vinylidene chloride, vinyl propionate, vinyl persate, 2-acrylamidopropanesulfonic acid and salts thereof. However, it is not necessarily limited to these.

The PVA-based polymer having a long chain alkyl group with 4 to 50 carbon atoms at the end can be produced by several methods, but industrially it has a long chain alkyl group with 4 to 5 carbon atoms. The most preferred method is to polymerize a monomer mainly composed of vinyl ester such as vinyl acetate in the presence of a mercaptan, and then saponify the resulting polyvinyl ester polymer by a conventional method.

On the other hand, as the starch, starches obtained from wheat, corn, rice, horseradish, amashiyo, tapioca, sago palm, etc. are used, but wheat starch and corn starch are generally suitable. Decomposition products of starch such as dextrin and oxidized starch produced from the raw starches mentioned above, or starch derivatives such as etherified starch, esterified starch, and cationized starch may also be used.

The blending ratio of starch (A) and PVA polymer (B) having a long chain alkyl group at the end is (A) = (B) = 10
A suitable ratio is 0:0.5 to 1:100, more preferably (A):(B)=10CM5 to 5:100. When the main purpose is to improve the storage stability of the starch aqueous solution, it is appropriate to add (B) to 100 parts by weight of starch (A) at least 0.5 parts by weight, more preferably at least 5 parts by weight. starch(
If the amount of (B) is less than 0.5 parts by weight relative to 100 parts by weight of A), the effect of adding (B) will not be significant. On the other hand, when the main purpose is to improve the quality of the starch film, it is appropriate to use 10 parts by weight or more, more preferably 20 parts by weight or more, based on 100 parts by weight of starch (A).

On the contrary, PVA-based polymers (B
) If the amount of starch (A) is less than 1 part by weight per 100 parts by weight, there is no difference in physical properties from (B) itself.

PVA with such starch and a long chain alkyl group at the end
The polymer composition according to the present invention, which is composed of a mixture with a polymer based on the polymer, has the following characteristics.

That is, the aqueous solution of the composition of the present invention has a lower aqueous solution than an aqueous solution of a mixture of starch and other PVA-based polymers (normal PVA, anion-modified PVA1 cation-modified PVA1 nonion-modified PVA and other modified PVA, etc.). It has high transparency, good storage stability, and very little change in viscosity over time, making it easy to handle. This is probably because the starch and the PVA polymer having a long chain alkyl group at the end have very good compatibility, so that the starch is uniformly dispersed in the aqueous solution without much agglomeration. A PVA-based polymer in which long-chain alkyl groups are randomly copolymerized also has the effect of somewhat improving the stability of an aqueous solution with starch compared to ordinary PVA, but the aqueous solution of the composition of the present invention is even more stable than that. It is.

It can be estimated from the viscosity behavior of a mixed aqueous solution of (B) and (A) that the PVA-based polymer (B) having a long-chain alkyl group at its terminal has a unique interaction with starch (A). That is, it has a Cl2823- alkyl group at the end and a polymerization degree of 1.
00, a mixture of PVA polymer with a saponification degree of 99.2 mol% and cornstarch in various ratios was poured into water and gelatinized by heating at 95°C for 2 hours with sufficient stirring to obtain a concentration of 5.
A % by weight aqueous solution was prepared. The viscosity of this aqueous solution at 90°C was measured using a B-type viscometer. Next, PVA with a polymerization degree of 550 and a saponification degree of 98.5 mol% (Kuraray Bhopal PVA
-105)/cornstarch system, the viscosity was similarly measured. The results are shown in Figure 1. In Figure 1, the solid line 1 represents PV having a long chain alkyl group at the end.
It is a polymer A/cornstarch system, and the viscosity behavior of the PVA-105/cornstarch system is shown by the dotted line 2. While the viscosity of PVA-105/corn starch aqueous solutions decreases as the PVA content increases, PVA polymer/corn starch aqueous solutions with long chain alkyl groups at the ends generally have PVA-105/corn starch aqueous solutions. 105
/Higher viscosity than cornstarch-based aqueous solutions (this P
The viscosity of the aqueous solution of the VA polymer itself is lower than the viscosity of the aqueous solution of PVA-105), and it shows a maximum when the content of the PVA polymer having a long chain alkyl group at the end is 10 to 30% by weight. This clearly shows that a PVA-based polymer having a long-chain alkyl group at the end and corn starch have a unique interaction.

Modified PVA copolymerized with long-chain alkyl groups also has the effect of improving the stability of mixed aqueous solutions, but it still has a tendency to gel, and is said to have no effect on modified starches. On the other hand, the PVA-based polymer (B) having a long-chain alkyl group at the end has a block-like bond between the long-chain alkyl group as the hydrophobic group at the end and the PVA moiety as the hydrophilic group. It is thought that in addition to having surfactant ability, the long chain alkyl group present at the end improves compatibility with starch, and the PVA part at one end facilitates dispersion in water, and this point is random. This is different from copolymerized modified PVA, which contains long-chain alkyl groups.

The change in aqueous viscosity of the composition of the present invention over time is very small, which indicates that it is effective in preventing the aging phenomenon of starch. Starch is generally composed of amylose and amylopectin, and this aging phenomenon is said to be caused by the crystallization of amylose in starch. It is a known fact that this amylose interacts with higher fatty acids and has good compatibility. The PVA-based polymer having a long-chain alkyl group at the end used in the present invention also has a long-chain alkyl group at the end similar to higher fatty acids, so it interacts with amylose. part facilitates dispersion into water.

This is thought to be the reason why starch has the effect of preventing starch from aging.

On the other hand, although little is known about the interaction with amylopectin, another component in starch,
It was found that the A-based polymer interacts with amylopectin as well as with amylose. That is, amylopectin separated from corn starch and Cl2H26-
It has a long chain alkyl group with a degree of polymerization of 280 and a degree of saponification of 98.
．． A mixture of 5 mol % PVA-based polymer at various ratios was poured into water and gelatinized by heating at 95° C. for 2 hours to prepare an aqueous solution with a concentration of 1.5% by weight. 20℃ of this aqueous solution
The viscosity and transmittance were measured.

0 Transmittance measurement method for aqueous solution Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength used: 6
50 nm Cell width 10 mm The results are shown in Table 1. P having a long chain alkyl group at the end
The viscosity at 20°C of 1.5% by weight of VA polymer alone is about 1 centipoise, which is almost the same as water, but as the proportion of PVA polymer with long chain alkyl groups at the end increases, the viscosity increases. has increased, and the transmittance has also increased.

Table-1 *Percentage of PVA polymer in total solid content Ordinary PVA with a degree of polymerization of 550 and a degree of saponification of 98.5 mol%
(Ri5 Revoverh PVA-105) and 7 myrovectin aqueous solution has a viscosity of about 8 centimeters and PVA-10
There was no change even when 5 was added, and the transmittance was almost unchanged at 16 to 18%. From this, it is presumed that the PVA-based polymer having a long-chain alkyl group at the terminal has a unique interaction with amylopectin. This is a feature not found in PVA copolymerized with long-chain alkyl groups and other PVA-based polymers.

The interaction of PVA-based polymers with long-chain alkyl groups at the ends with not only amylose but also amylopectin may be the reason for their good compatibility not only with raw starch but also with oxidized starch and other modified starches. Seem.

In addition, the film formed from the aqueous solution of the composition of the present invention is extremely homogeneous and has good transparency, and has higher strength and elongation than other mixtures of PVA-based polymers and starch. It shows excellent film properties. The reason for this is that the long-chain alkyl group at the end acts to enhance the interaction with starch.
It is thought that the hydrophilic PVA portion on the other hand prevents the starch from coagulating with each other and has the function of uniformly dispersing it in the form of fine particles. This effect is due to the hydrophobic long-chain alkyl group and the hydrophilic PV.
It is thought that this works very effectively because part A exists in the form of a block.

The starch (A) and the PVA polymer (B) having a long chain alkyl group at the end can be mixed by mixing the two in powder form and then adding water or pouring it into water to gelatinize it. ) and (B)
Any method may be used, such as gelatinizing each separately and then mixing them. Plasticizers, colorants, fillers, salts, boric acid, borax, other water-soluble polymers, surfactants, and other additives may be added to the mixture.

The composition of the present invention can be used as a sizing agent for fibers, particularly a sizing agent for warp yarns, a paper processing agent, an adhesive, a film forming agent, and the like.

Next, as a reference example, PVA with a long chain alkyl group at the end
An example of a method for producing a polymer is shown below.

Reference Example 960 parts of vinyl acetate (hereinafter abbreviated as VAc), 230 parts of methanol, and n-dodecylmercaptan (hereinafter referred to as n-D
After placing 0.99 parts of DM) in a reaction vessel and purging the inside sufficiently with nitrogen, the external temperature was raised to 65°C, and when the internal temperature reached 60°C, 0.99 parts of 2.2-azobisisobutyronitrile was added.
．． 10 parts of methanol containing 174 parts were added. Immediately
60 parts of a VAc/methanol solution (VAc concentration 80%) containing 15.3 parts of -D D M was added uniformly over 5 hours. The polymerization rate after 5 hours was 48.2%.

After 5 hours, the container was cooled and the remaining Ac was expelled from the system under reduced pressure while adding methanol to obtain a methanol solution of PVAc (concentration 72%). Take a part of this methanol solution and P
VAc concentration is 50%, a methanol solution of NaOH is added so that the molar ratio of [NaOH]/[VAcAc] is 1, and the mixture is saponified at 40°C to obtain a saponification degree of 99.2.
% PVA was obtained. The degree of polymerization calculated from [η] in acetone using the Nakataka formula was 82.

PVA-based polymers have long chain alkyl groups at the ends of the starch and starch.
Since part A has the function of stabilizing the dispersion of starch in water, the aqueous solution has good storage stability and is effective in preventing starch from aging.

In addition, since the starch is uniformly present in the form of fine particles, the films formed from these aqueous solutions are homogeneous, have good transparency, and have excellent film properties.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the following Examples are not intended to limit the present invention in any way. All percentages in the examples are by weight unless otherwise specified.

The details of the PVA-based polymer having a long-chain alkyl group at the end used are shown in Table 2.

(Left below) Example 1 PVA-based polymer having a long-chain alkyl group at the end (P-2
) and cornstarch was heated and dissolved in an autoclave at 125° C. for 1 hour to prepare an aqueous solution with a solid content concentration of 5%. The viscosity of the aqueous solution at 20°C was measured immediately after preparation of the aqueous solution and one week later. The state of the aqueous solution after -1 week was also observed. Similarly, a PVA-based polymer (P-6) having a long-chain alkyl group at the end was also investigated.

As a comparative example, a solution of cornstarch alone and a polymerization degree of 55
0 and a solution of PVA (Kuraray Boval PVA-105)/cornstarch system with a sulfurization degree of 98.5 mol% was similarly measured.

The results are shown in Table 3. The solution using PVA-105 showed a large change in viscosity over time and was easily separated. Corn starch alone systems also tend to gel quickly. On the other hand, it can be seen that solutions using PVA-based polymers having long-chain alkyl groups at the terminals show less change in viscosity over time and good storage stability.

Example 2 A mixture of PVA-based polymers having long-chain alkyl groups at various terminals and corn starch at a ratio of 50:50 (by weight) was heated and dissolved in hot water at 95°C for 2 hours to obtain a 5% concentration. An aqueous solution was prepared. The viscosity of this aqueous solution at 20°C was measured immediately after dissolution and 2 days later.

As Comparative Example 3, the degree of polymerization was 1750. PVA (Kuraray Boval PVA-117) with a saponification degree of 98.5 mol% and a polymerization degree of 700. Long chain alkyl group-modified PVA (PVA-L) with saponification degree of 98.6 mol%, Comparative Example 5, copolymerization of 3 mol% of persatic acid and 1 mol% of itaconic acid, polymerization degree of 700, saponification degree of 96.5 An aqueous solution using mol % of copolymerized modified PVA (PVA-V) and PVA-based polymer P-8 as Comparative Example 6 was similarly prepared and the viscosity was measured.

The results are shown in Table 4. The number of carbon atoms in the long chain alkyl group at the end must be 4 or more; if it is 3 or less, there will be little effect. The use of modified PVA copolymerized with long-chain alkyl groups also slightly improves the transparency of aqueous solutions, but there is a tendency for gelation, which poses a problem in handling. On the other hand, an aqueous solution using a PVA-based polymer having a long chain alkyl group having 4 or more carbon atoms at the end has little change in viscosity over time and is fluid and easy to handle.

Table 4 Example 3 As Invention Example 8, PV having a long chain alkyl group at the terminal
Using P-2 as the A-based polymer, 20P-2 and oxidized starch Mermaid M-200 (manufactured by Shikishima Starch Co., Ltd.)
A 10% aqueous solution was prepared by dissolving it in hot water at 5°C.

The system to which a PVA-based polymer having a long-chain alkyl group at the end was added had better transparency than an aqueous solution of oxidized starch alone, indicating good compatibility.

This is shown by the transmittance (solid line 1) in FIG.

As Comparative Example 7, the transmittance of an aqueous solution of PVA (Kuraray Boval PvA-105) with a degree of polymerization of 5501 and a degree of saponification of 98.5 mol% and oxidized starch Mermaid M-200 is shown in Figure 2 (dotted chain line in 3). , the transmittance hardly changes, indicating poor compatibility.

As Comparative Example 8, lauryl vinyl ether was copolymerized with a degree of polymerization of 70o1 and a degree of saponification of 98.6 mol%.
Example 8 of the present invention was prepared using long-chain alkyl group copolymerized modified PVA (PVA-L) and oxidized starch-z-mate M-200.
Transmittance was measured in the same manner. The results are shown in Figure 2 (20 dotted line), and the compatibility with oxidized starch is better than that of PVA-105/oxidized starch, but the PVA-based polymer having a long-chain alkyl group at the end of Inventive Example 8 It is inferior to the system in which it is added.

*Method for measuring transmittance of aqueous solution: Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength used: 65
0 nm1 Cell width 10 mmExample 4 As Inventive Example 9, PV having a long chain alkyl group at the terminal
A-based polymer (P-3) was dissolved in hot water to prepare an aqueous solution with a concentration of 10%. On the other hand, cornstarch was gelatinized by heating at 120° C. for 1 hour to prepare an aqueous solution with a concentration of 10%. After mixing these two solutions at various ratios, a film was formed on a drum set at 70°C. The film was conditioned for one hour at 20° C. and 65% RH, and then the strength and elongation of the film was measured.

Comparative Example 9: Polymerization degree: 5501, saponification degree: 98°, 5 mol%
PVA (Kuraray Boval PVA-105) was copolymerized with 0.6 mol% lauryl vinyl ether as Comparative Example 10, and the polymerization degree was 70o1 and the saponification degree was 98.6 mol%. Long chain alkyl group copolymerization modified PVA (PVA-L). The strength and elongation of the film was measured in the same manner as in Invention Example 9.

The results are shown in Table 5, and the PVA-based polymer/cornstarch-based film having a long-chain alkyl group at the end was PVA-1.
05/j->Starch-based PVA-L/Corn starch-based film has higher strength and elongation (indicating good film physical properties.The film also has high transmittance and transparency compared to that of the comparative example. In terms of film properties, PVA-based polymers with long-chain alkyl groups at the terminals have better compatibility with cutting powder than modified PVA copolymerized with long-chain alkyl groups. Because of this, the physical properties of the film are also good.

*Measurement method of film physical properties Sample used: Takafu Autograph DC3-100 model (manufactured by Takafusa Seisakusho) Radius: 15 mm 1 Thick: approx. 60 am.

Measurement length 50 mm s Tensile speed 500 mm/min*
Measuring method of film transmittance Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength 650
nm Blank Film of PVA-105 alone (hereinafter referred to as blank space) FIG. 1 is a diagram showing the relationship between the content of the PVA-based polymer in the PVA-based polymer and cornstarch mixture and the viscosity of the aqueous solution. In the figure, X represents the content (wt%) of the PVA polymer based on the total solid content, and Y represents the viscosity of the aqueous solution measured by a B-type viscometer at 20°C.

Figure 2 shows the PVA in the PVA-based polymer and oxidized starch mixture.
FIG. 3 is a diagram showing the relationship between the content of a system polymer and the transmittance of an aqueous solution. In the figure, X represents the content (wt%) of the PVA polymer in the total solid content, and Y represents the transmittance of the aqueous solution at 20°C.

Claims (2)

[Claims] (1) Starch (A) and polyvinyl alcohol polymer (B) having a long chain alkyl group with 4 to 50 carbon atoms at the end
A polymer composition consisting of (2) The weight mixing ratio of (A) and (B) is 100; 0.5
The polymer composition according to claim 1, wherein the ratio is 1:100 to 1:100.