JPS62288644A - Starch-based polymer composition - Google Patents

Abstract

PURPOSE:To provide a polymer composition composed of starch, a specific polyvinyl alcohol polymer and a polyvinyl alcohol, giving an aqueous solution 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, 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 and (C) a polyvinyl alcohol having a polymerization degree of 100-3,000, preferably 200-2,500 and saponification degree of >=50mol%, preferably >=70mol%. The amount of the component B is 1-3,000pts.(wt.) per 100pts. of the component A and that of B+C is 2-10,000pts. The amount of the component C is 1-10,000pts. per 100pts. of the component B.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Product] The above-mentioned present invention comprises starch (A) and a polyvinyl alcohol polymer (B) having a long chain alkyl group having 4 to 50 carbon atoms at the end.
and polyvinyl alcohol (C), and which have very good compatibility.

A mixture of rice hull strained polyvinyl alcohol (hereinafter abbreviated as PVA) and starch is used as a warp sizing agent for textiles because it is water-soluble and has good film-forming ability, and the powder is inexpensive. It has been used as a paper processing agent, etc. However, since both PVA1i1G powders are polymeric compounds, their compatibility is poor, 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 not transparent. The properties of the film are not very good.

In order to improve the compatibility between PVA and starch, various chemically modified flours such as starch derivatives such as etherified starch, esterified starch, and cationized powder, and starch decomposition products such as oxidized starch and dextrin are used as V powder. However, starch derivatives have the disadvantage of high cost;
On the other hand, starch decomposition products have a smaller molecular weight than the original starch, so although the stability of the mixed aqueous solution with PVA is improved,
The physical properties of the film made from this mixed aqueous solution are not very good (or even worse).That is, even if these modified starches are used, the compatibility with PVA is still insufficient.

On the other hand, it is known that the use of modified PVA copolymerized with a long-chain alkyl group having 4 to 20 carbon atoms improves the compatibility with raw starch (JP-A-56-14544, JP-A-Sho. 56-55440), 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. In addition, the above-mentioned modified starch has no effect.The production technology of PVA-based polymers having long-chain hydrocarbon alkyl groups at the end is already known (Japanese Patent Publication No. 48-1831,
JP-A-58-108207).

However, the technology regarding the compatibility between this PVA-based polymer and starch is not yet known.

1. Raw starch 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 intermediate physical properties between the two.However, the two are essentially compatible with each other. However, the stability of the mixed aqueous solution is poor (because it is not a mixed aqueous solution), and there are various problems in handling such as separation and increase in viscosity over time.Also, the physical properties of molded products made from these mixed aqueous solutions are not satisfactory. It is not something that can be done.

121", as a result of intensive study under such circumstances, the present inventor found that a mixture of powder (A) and PVA (C) contains a long chain with 4 to 50 carbon atoms at the end. When the PVA polymer (B) having an alkyl group is added, the mixture thereof has very good compatibility, the stability of this mixed aqueous solution is improved, and the change in viscosity of the mixed aqueous solution over time is small. The inventors completed the present invention by discovering that a film prepared from a mixed aqueous solution has excellent transparency and good coating properties.

The terminal hydrophobic group-modified PVA polymer (B) having a long chain alkyl group having 4 to 50 carbon atoms at the terminal used in the present invention will be explained. As the terminal long-chain alkyl group, one having 4 to 50 carbon atoms is suitable. When the number of carbon atoms is less than 4, it is not much different from unmodified PVA and its compatibility with V powder is not good. In addition, polymers with carbon numbers exceeding 50 have too strong hydrophobicity, resulting in poor water solubility of the polymer itself, resulting in poor compatibility with starch, which also fails to achieve the purpose of the present invention, and has 4 to 5 carbon atoms.
The number of carbon atoms is preferably 0, but preferably 8 to 24 carbon atoms. Examples of such groups include straight alkyl groups having 4 to 50 carbon atoms, branched alkyl groups, alkylaryl groups, etc., 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 3000. Desirably 50-25
00 is appropriate. There are no particular restrictions on the degree of saponification, but it is usually 50 mol% or more, preferably 70 mol% or more.

In addition, the polymer may contain a small amount of units in addition to vinyl alcohol units and residual vinyl ester units such as vinyl acetate. 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-
Vinylpyrrolidone, vinyl chloride, vinylidene chloride, a
Examples include vinyl pionate, vinyl persate, 2-acrylamidopropanesulfonic acid and salts thereof. However, it is not necessarily limited to these.

The PVA-based polymer (B) having a long-chain alkyl group with 4 to 50 carbon atoms at the terminal as described above can be produced by several methods, but industrially, long-chain alkyl groups with 4 to 50 carbon atoms can be produced. The most preferred method is to polymerize a monomer mainly consisting of a vinyl ester such as vinyl acetate in the presence of a mercaptan having a group, and then saponify the resulting polyvinyl ester polymer by a conventional method.

In addition, as PVA (C), the degree of polymerization is 100 to 30,001.
Preferably 200-2500. In addition to ordinary PVA having a saponification degree of 50 mol % or more, preferably 70 mol % or more, anion-modified, cation-modified, or other nonion-modified PVA polymers having a long-chain alkyl group at the end may be used.

On the other hand, as the starch (A), flours from wheat, corn, rice, sweet potato, tapioca, sago palm, etc. are used, but wheat flour and cornstarch 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-based polymer (B) and PVA (C) having long-chain alkyl groups at the terminals is as follows:
A wide range of effects can be seen, from those in which A) occupies the majority to those in which a small amount of starch is blended, that is, [(B) + (C)] is 22 to 10,000 parts by weight per 100 parts by weight of (A).
The weight is appropriate, preferably 5 to 5000 parts by weight.

[(B) + (C)] is 2 for 100 parts by weight of (A)
If the physical properties are less than
(C)] exceeds 110,000 weight, starch has no effect. Here, it is suitably 1 to 10,000 parts by weight, preferably 1 to 5,000 parts by weight, per 100 parts by weight of (C)Lt(B).

In addition, the ratio of the PVA polymer (B) having a long chain alkyl group at the terminal to the starch (A) is 1 to 3000 parts by weight, preferably 5 to 100 parts by weight of (B).
~1000 parts by weight is preferred. When the main purpose is to improve the storage stability of the starch aqueous solution, it is appropriate to add 1 part by weight or more, more preferably 5 parts by weight or more of (B) to 100 parts by weight of the starch (A). (B) per 100 parts by weight of starch (A)
) is less than 1 part by weight, the effect of adding (B) is not so great.

On the other hand, if the main purpose is to improve the quality of the starch film, starch (A) 1
It is appropriate for (B) to be at least 10 parts by weight, preferably at least 20 parts by weight, per 00 parts by weight. Conversely, PVA-based polymer (B) having a long-chain alkyl group at the end is starch (A) 100%
If the amount exceeds 5,000 parts by weight, the effect of adding powder is not achieved.

Such starch (A), Z having a long chain alkyl group at the end
The starch-based polymer composition according to the present invention, which is composed of a mixture of PVA-based polymer (B) and PVA (C), has the following characteristics.

That is, the aqueous solution of the composition of the present invention contains starch (A) and PVA.
Compared to the aqueous solution of the mixture with (C), the aqueous solution has high transparency, good storage stability, and very small change in viscosity over time, making it easy to handle.

This is starch (A) and PV with a long chain alkyl group at the end.
Because it has very good compatibility with the A-based polymer (B), the starch is uniformly dispersed in the aqueous solution without much agglomeration, and it also has a long-chain alkyl group at the end! PVA polymer (B)
Since the compatibility between PVA (C) and PVA (C) is good, the overall compatibility is good and the solution stability is also considered to be good. 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 C12825-alkyl group at the end and a polymerization degree of 1.
00, a mixture of PVA-based 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 thorough stirring to obtain a concentration of 5.
A % by weight aqueous solution was prepared. The viscosity of this aqueous solution at 90°C was determined using a B-type viscometer. Next, PVA with a polymerization degree of 550 and a degree of keratinization 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 represented by the dotted line 2. While the viscosity of PVA-105/cornstarch aqueous solutions decreases as the PVA content increases, PVA-based polymers/cornstarch aqueous solutions with long chain alkyl groups at the ends generally have PVA-105/cornstarch 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. 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 has affinity for other PVA, making this mixture highly compatible. This is considered to be a good improvement, and this point is different from copolymerized modified PVA in which long-chain alkyl groups are randomly included.

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 generally consists of amylose and amylopectin, and this aging phenomenon is said to be caused by 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 the powder is effective in preventing the aging phenomenon.

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 Cl2H2S-
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.

Table-1 *Percentage of PVA polymer in total solid content Transmittance measurement method of aqueous solution with 0 Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength used: 85
0 nm Cell width 10 mm The results are shown in Table-1.

1 made only of PVA-based polymers with long-chain alkyl groups at the ends
．． The viscosity of 5% by weight at 20°C is about 1 centipoise, which is almost the same as water, but it does not struggle and as the proportion of PVA polymer with long chain alkyl groups at the end increases, the viscosity increases and the transmittance also increases. It's getting expensive. An aqueous solution of ordinary PVA (Kuraray Boval PvA-105) and amylopectin with a polymerization degree of 55o1 and a saponification degree of 98.5 mol% has a viscosity of about 8 centipoise, which does not change even when PVA-105 is added, and a transmittance of 16 to 18%. Almost nothing changed.

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 is made of PVA-based polymer (C).
The strength and elongation of the film are higher than that of a mixture consisting only of starch (A) and starch (A), and the film exhibits excellent physical properties. The reason for this is that the terminal long-chain alkyl group of the PVA polymer (B), which has a long-chain alkyl group at the terminal, functions to enhance the interaction with the starch (A), and one hydrophilic PVA portion This is probably because the starch (A) is uniformly dispersed in the form of fine particles because it prevents agglomeration of starches and has good compatibility with PVA (C). This effect is thought to be very effective due to the block-like presence of the hydrophobic long-chain alkyl group and the hydrophilic PVA moiety.

When combining starch (A), a PVA polymer (B) with a long-chain alkyl group at the end, and PVA (C), mix the three in powder form and then add water or pour it into water to form a paste. Any method may be employed, such as gelatinizing (A), (B), and (C) separately and then mixing them. Further, when gelatinizing raw starch, it may be done under normal pressure or high pressure, but it is preferable to use starch gelatinized under high pressure in terms of physical properties.

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, 2° 2-azobisisobutyronitrile was added.
．． 10 parts of methanol containing 174 parts were added. Immediately
-VAC/:A'l)-le solution M containing 15.3 parts of DDM
60 parts (VAc concentration 80%) were added uniformly over 5 hours. The polymerization rate after 5 hours was 48.2%.

After 5 hours, the container was cooled and the remaining VAC was expelled from the system together with methanol under reduced pressure while adding methanol to obtain a methanol solution of PVAc (W4 degree 72%). Take a part of this methanol solution and P
VAc concentration 50%, [NaOH]/[VAc] = 0
．． Add a methanol solution of NaOH so that the molar ratio is 1 (molar ratio), and saponify at 40°C to obtain a saponification degree of 99.2%.
of PVA was obtained. The degree of polymerization calculated from [nl] in acetone using the Nakataka formula was 82.

PVA-based polymers have long chain alkyl groups at the ends of the starch and starch.
Part A has the function of stabilizing the dispersion of starch in water and has good compatibility with other PVA, so 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.

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 the same way. All percentages and parts in the examples are based on 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.

Example 1 Generally, ordinary PVA and oxidized starch are least compatible at a ratio of 50:50 (based on weight). Therefore, as Example 1 of the present invention, oxidized starch Mermaid M-
200 (manufactured by Shikishima Starch Co., Ltd.) and PVA (Kuraray Bhopal PV) with a degree of polymerization of 1750 and a degree of saponification of 98.5 mol%.
A-11? ) in a ratio of 50+50 (based on weight), 5 to 70 parts of PVA-based polymer (P-2) having a long-chain alkyl group at the end was added to 100 parts of oxidized starch, and the mixture was mixed in water. and heated to dissolve at 95° C. for 2 hours to prepare an aqueous solution with a solid content concentration of 10%. 2 of the aqueous solution
The viscosity at 0°C was measured immediately after preparation of the aqueous solution and 2 days later.

The state of the aqueous solution after 2 days was also observed.

As a comparative example, a sample to which P-2 was not added was also measured in the same manner.

The results are shown in Table 3, and the solution without P-2 showed a large change in viscosity over time and was easily separated into layers.

On the other hand, it can be seen that the solution containing the PVA-based polymer (P-2) having a long-chain alkyl group at the end shows less change in viscosity over time and good storage stability.

Table 3 Example 2 As Examples 2 to 6 of the present invention, 45 parts of cornstarch water-soluble TFF (8% 5%) gelatinized at 120°C was mixed with 5 parts of PVA-based polymers having long chain alkyl groups at various terminals. % concentration aqueous solution and PVA with a polymerization degree of 5501 and a saponification degree of 98.5 mol% (Kuraray Boval PVA-105) + 7) 5
A mixed aqueous solution was prepared by adding a total of 45 parts of the % concentration aqueous solution.

The viscosity of this water itwt at 20°C was measured immediately after dissolution and 2 days later.

As Comparative Example 2, 45 parts of an aqueous cornstarch solution (11 degrees 5%) gelatinized at 120°C was added with a polymerization degree of 1750 and Cf
10 parts of water iWM with a 5% concentration of DPVA (') Lalepoval PVA-117) with a degree of k conversion of 98.5 mo/l/% and P
A mixed aqueous solution containing 45 parts of a 5% aqueous solution of VA-105 was similarly prepared and its viscosity was measured. As comparative example 3,
Aqueous solution of corn starch gelatinized at 120℃ (5% a degree
), 5% of long-chain alkyl group copolymerized modified PVA (PVA-L) with a polymerization degree of 7001 and a saponification degree of 98.6 mol%, in which 0.6 mol% of lauryl vinyl ether was copolymerized.
A mixed aqueous solution was similarly prepared by adding 10 parts of a 5% aqueous solution of PVA-105 and 45 parts of a 5% aqueous solution of PVA-105, and the viscosity was measured. As Comparative Example 4, 45 parts of an aqueous corn starch solution (concentration 5%) gelatinized at 120°C was copolymerized with 3 mol% of persatic acid and 1 mol% of itaconic acid with a polymerization degree of 7.
001 modified PVA with a saponification degree of 96.5-11% (
PVA-V) (7) 10 parts of a 5% aqueous solution and PVA-
A mixed aqueous solution containing 45 parts of a 5% aqueous solution of 105 was prepared in the same manner, and the viscosity was measured. As comparative example 5, 120
Corn starch aqueous solution (concentration 5%) gelatinized at ℃ 45
In part, a PVA-based polymer having a long-chain alkyl group at the end (
P-8) 5% concentration of aqueous M2O part and PVA-105
A mixed aqueous solution containing 45 parts of a 5% aqueous solution was prepared in the same manner 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, and if it is 3 or less, it is not very effective. The use of modified PVA copolymerized with long-chain alkyl groups also slightly improves the storage stability of aqueous solutions, but there is a tendency for gelation, which poses problems in handling. On the other hand, a 1 g solution of water using a PVA-based polymer having a long chain alkyl group having 4 or more carbon atoms at its terminal shows only a small change in viscosity over time (it is fluid and easy to handle).

Table 4 Example 3 As Invention Example 7, the degree of polymerization was 1750 and the degree of saponification was 88.5.
Mol% PvA (Kuraray Bobbal PvA-217
) 62 parts, Kako R Powder Cofilm 8.0 (manufactured by Tamako National Co., Ltd.) 35 parts, P having a long chain alkyl group at the end
Add 3 parts of VA polymer (P-6), pour this mixture into water, heat and dissolve at 95°C for 2 hours to prepare an aqueous solution with a concentration of 10%, and measure the transmittance of this aqueous solution at 20°C.・Invention Example 8 and L4, 62 parts of PVA-217 ・Chemical starch Vetrosize L-2B (manufactured by Hikaku Kagaku Co., Ltd.) 35
An aqueous solution containing 3 parts of P-6 was also prepared in the same manner, and the transmittance was measured.

As Comparative Example 6, a 10% aqueous solution containing 62 parts of PVA-217 and 35 parts of Cofilm 80 was prepared, and the transmittance at 20°C was measured. In addition, as comparative example 7, P
An aqueous solution consisting of 62 parts of VA-217 and 35 parts of Vetrosize L-2B was similarly prepared and the transmittance was measured.

Further, as Comparative Example 8, 62 parts of PVA-217, 35 parts of Cofilm 80, and 0.6 parts of lauryl vinyl ether were prepared.
Mol% copolymerized, degree of polymerization 700, degree of saponification 98.6
Mol% of long-chain alkyl group copolymerized modified PVA (PVA-
An aqueous solution containing 3 parts of L) was also prepared in the same manner as in Invention Example 7, and the transmittance was measured. The results are shown in Table-5.

The aqueous solution to which the PVA-based polymer having a long-chain alkyl group at the end was added had a higher transmittance than the aqueous solution consisting only of PVA-217 and modified starch, indicating improved compatibility. Also, PVA copolymerized with long-chain alkyl groups
It can also be seen that there is almost no effect of improving the compatibility with these chemically engineered V powders.

Table-5 *Method for measuring transmittance of aqueous solution Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength used 8
50 nm Cell width 10 mm Example 4 As Example 9 of the present invention, the degree of polymerization was 17,501 degrees/degree of phosphorization was 98.
5 mol% PVA (Kuraray Boval PVA-117)
and oxidized starch Mermaid M-200 (Shikishima Starch Co., Ltd.)
A PVA-based polymer (P-2) having a long chain alkyl group at the end was added to a mixture of 7:3 C'Ji (based on the amount of C'Ji) and dissolved in hot water at 95°C to form an aqueous solution with a concentration of 10%. was prepared. The system to which a PVA polymer having a long chain alkyl group at the end was added had better transparency and better compatibility than an aqueous solution consisting only of oxidized powder and PVA-117. This is shown by the transmittance (solid line 1) in FIG.

As Comparative Example 9, in place of the PVA-based polymer (P-2) having a long chain alkyl group at the end of Invention Example 9, a polymer with a polymerization degree of 55o was used.
1 PVA with saponification degree of 98.5 mol% (PVA-105
) is shown in FIG. 2 (dotted chain line 3), which shows that the transmittance hardly changes and the compatibility is poor.

As Comparative Example 10, 0.6 mol% of lauryl vinyl ether was copolymerized instead of the PVA polymer (P-2) having a long chain alkyl group at the end of Inventive Example 9, with a polymerization degree of 700.
．． Transmittance was measured in the same manner as in Inventive Example 9 using long-chain alkyl group copolymerized modified PVA (PVA-L) with a saponification degree of 98.6 mol%. 21st result!1 (20 dotted line)
As shown in the figure, the compatibility with oxidized starch is better than that of PVA-105, but it is inferior to the system of Example 9 in which a PVA polymer having a long chain alkyl group at the end is added.

*Method for measuring transmittance of aqueous solution: Hitachi spectrophotometer (manufactured by Hitachi, Ltd.) Wavelength used: 65
0 nm, cell width 10 mm Example 5 Inventive Example 10, polymerization degree 1750. Saponification degree 88.
5 mol% PVA (Kuraray Boval PVA-217)
62 parts of oxidized starch Cofilm 80 (manufactured by Tamako National Co., Ltd.) and 35 parts of P having a long chain alkyl group at the end.
Three parts of VA polymer (P-3) were added, and the mixture was poured into water and dissolved by heating at 95° C. for 1 hour to prepare an aqueous solution with a concentration of 10%. Using this aqueous solution, a film was formed on a drum set at 70°C, and the film was conditioned for one week at 20°C and 65% RH, and then the strength and elongation of the film was measured.

As Example 11 of the present invention, 62 parts of PVA-217, 3 parts of oxidized starch Mermaid M-200 (manufactured by Shikishima Starch Co., Ltd.)
Invention Example 11 also applies to 5 parts plus 3 parts of P-3.
The strength and elongation of the film was measured in the same manner.

Comparative Example 111L4 62 parts of PVA-217 and 35 parts of Cofilm 80 were added, Comparative Example 12 was PVA-217.
62 parts of 217 and 35 parts of Mermaid M-200, and 62 parts of PVA-217 as Comparative Example 13.
Polymerization degree: 7oO1 saponification degree: 98 by copolymerizing 35 parts of Cofilm 80 with 0.6 mol% of lauryl vinyl ether
゜6 mol% long chain alkyl group copolymerized modified PVA (PV
A-L), the strength and elongation of the film was measured in the same manner as in Inventive Example 10.

The results are shown in Table 6, and the film obtained by adding the PVA polymer having a long chain alkyl group at the end of the present invention has higher strength and elongation than the film without the addition, and is a good film. Indicates physical properties. Furthermore, when the film of the present invention example was closely observed with an optical a mold mirror, it was found that the oxidized starch was more finely dispersed and uniformly dispersed than that of the comparative example! 1! I can pass. In this way, in terms of film properties, PVA polymers with long chain alkyl groups at the terminals have better compatibility with starch than modified PVA copolymerized with long chain alkyl groups. It can be seen that it is in good condition.

Table 6 *Measurement method for film physical properties Sample used by Takafu Autograph DC3-100 (manufactured by Takafuji Seisakusho) Width 15 mm, thickness approximately 60 μm 1 Figure 1 shows P
FIG. 2 is a diagram showing the relationship between the content of a PVA-based polymer in a mixture of VA-based polymer and cornstarch and the viscosity of an aqueous solution.

In the figure, X is the content of PVA polymer based on the total solid content (
% by weight), and Y represents the viscosity of the aqueous solution at 20°C using a B-type viscometer.

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) A starch-based polymer composition comprising starch (A), a polyvinyl alcohol-based polymer (B) having a long-chain alkyl group having 4 to 50 carbon atoms at the end, and polyvinyl alcohol (C). (2) The mixing ratio of (A) and [(B) + (C)] is (A)
[(B)+(C)] is 2 to 100 per 100 parts by weight
00 parts by weight, (C) is 1 to 10,000 parts by weight per 100 parts by weight of (B), and (B) is 1 to 3,000 parts by weight per 100 parts by weight of (A). The starch-based polymer composition according to item 1.