JPH0670083B2 - Method for producing modified starch - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a modified starch using a modified dimethylpolysiloxane, which comprises an adhesive and a binder having water resistance and oil resistance. It can also be used as a sizing agent, a coating agent, etc., and can also be used as a filler for polymers.

(Prior Art) As a method for imparting water resistance to starch, etherification with epichlorohydrin, esterification with polymerized phosphate,
There is a method of suspending starch by acetalization with aldehyde. These cross-linked starches have a certain degree of water resistance, but they are not sufficient, they do not easily form a paste, and it is difficult to use an ordinary coating method, and there is a drawback that they do not form a film and do not form a rupture film. .

Since N-methylolpropionamide etherified starch (US Pat. No. 3,101,330) has an N-methylol group, it can be rendered three-dimensional by heating or an acid catalyst after application to exhibit water resistance. However, during its production, the acid amide group is hydrolyzed to form a carboxyethylated product, which impairs the water resistance and causes a problem that the N-methylol group is condensed and gels during the reaction.

Further, a method for modifying starch using an organosilane has been proposed (JP-A-59-179501 and JP-A-59-207902), but since the silicon compound is bonded in a monomer unit, water resistance and There is a problem that the oil resistance is weak.

(Problems to be Solved by the Invention) As described above, the cross-linked starch formed by epichlorohydrin, polymerized phosphate, aldehyde, etc., has insufficient water resistance, and N-
Methylolpropionamide etherified starch has the problems that water resistance cannot be obtained unless it is three-dimensionalized by heating or acid catalyst, and that the method using organosilane has poor water resistance and oil resistance. At present, there is no modified starch that has strong properties and is easy to manufacture and use.

(Means for Solving Problems) As a result of intensive research to solve the above problems, starch was Modified starch obtained by reacting with a modified dimethylpolysiloxane which is a polymer of a silicon compound, using a compound having an (X = O or S) group, an amine, a Lewis acid, a tin salt or an aluminum salt of a carboxylic acid as a catalyst. Have been found to have strong water and oil resistance.

In the method for producing a modified starch of the present invention, a modified dimethylpolysiloxane is suspended in water, starch is added to this suspension, and then the above-mentioned catalyst is added and the reaction is carried out with sufficient stirring. However, the catalyst may be added before adding the starch. The reaction temperature may be room temperature, but it is advantageous to heat it to a temperature below the gelatinization temperature of starch (generally about 40 ° C.).

When the reaction is carried out in a wet manner as described above, the modified starch of the present invention can be obtained by washing with water, dehydration and drying by a known method after the reaction.

It is also possible to heat the starch to make it into a paste solution and then add the modified dimethylpolysiloxane and the above-mentioned catalyst to the reaction. The reaction temperature after gelatinizing the starch may be equal to or lower than the gelatinization temperature of the starch.

Thus, the modified starch of the present invention obtained by the gelatinization reaction can be used as it is, or can be dried by drum drying or the like to be pulverized.

Further, by using a suitable mixing or kneading device, the modified dimethylpolysiloxane and the above-mentioned catalyst are mixed with the starch at a water content of 2 to 50%, whereby the work is performed at a temperature higher than the gelatinization temperature of the starch for a short time. It becomes possible to do it.

As the compound having an (X═O or S) group, as X═O, for example, urea, formamide, acrylamide and dimethylformamide can be used. Examples of X = S include thiourea and the like. These are used as 5-15% aqueous solutions or as solids or stock solutions. The added amount is 0.005 to 10% with respect to starch.

Amines include primary amines such as n-propylamine, secondary amines such as diethylamine, tertiary amines such as trimethylamine, quaternary ammonium compounds such as tetramethylammonium hydroxide, diamines such as ethylenediamine, and triethanolamine. Unsaturated amines such as amino alcohols and allylamine can be used. They are,
Used as a 5 to 15% aqueous solution or as a neat solution.
The added amount is 0.005 to 20% with respect to starch.

As the Lewis acid, stannous chloride, stannic chloride, ferric chloride, zinc chloride or the like can be used. These are 5
Used as a ~ 15% aqueous solution, solid or undiluted. The added amount is 0.005 to 10% with respect to starch.

As the tin salt of carboxylic acid, tin acetate, dibutyltin dilaurate or the like can be used, and as the aluminum salt, aluminum acetate or the like can be used. These are used as a solid or undiluted solution as a 5 to 15% aqueous solution. The added amount is 0.005 to 10% with respect to starch.

Examples of the starch raw material that can be used for producing the modified starch of the present invention include wheat starch, potato starch, corn starch, honey starch, tapioca starch, sago starch, rice starch,
Waxy corn starch, untreated starch such as high amylose corn starch or wheat flour, tapioca starch,
Also included are starch-containing substances such as corn flour and rice flour, or those obtained by subjecting these to etherification, crosslinking, oxidation, acid treatment and the like.

In the present invention, the modified dimethylpolysiloxane that can be used as the modifier is represented by the following general formula.

[Wherein X is an optionally molecular formula a group having a polyether unit substituted _{-CH 2 CH 2 O (C 2} H 4 O) a (C 3 H 6 O) bR (R is a monovalent organic group, a + b> 14, a / a + b> 0.35). Y is an optionally substituted amino group, or -C
l, -CH = CH ₂ and Represents a group from the group, 1 is an integer, m is an integer from 0 to 20,
n is an integer of 1 to 20, and the average molecular weight is 1,000 to 100,000. The amount of the modified dimethylpolysiloxane added is 0.01 to 10% with respect to the starch.

(Function) The modified starch of the present invention exhibits hydrophobicity and oleophobicity only by allowing a small amount of modified dimethylpolysiloxane to act.
When the modified starch of the present invention is applied to a paper or plate by impregnation, the surface of the modified starch is covered with dimethylpolysiloxane, so that water resistance and oil resistance are exhibited. Further, as a secondary effect, the strength of the paper is improved.

The modified starch of the present invention using the polyether modified dimethylsiloxane has good dispersibility in water. But,
When it is made into a paste and applied to paper or the like, dried after impregnation, the polyether part is dislocated and shows hydrophobicity and oleophobicity. On the other hand, the modified starch of the present invention using the modified dimethylsiloxane having no polyether portion has poor dispersibility because it does not get wet with water and remains floating in water. It is necessary to use properly depending on the application.

The modified starch paste solution of the present invention has a higher viscosity than the starting starch, but does not adversely affect the dispersion of pigments and the like.

(Effects of Examples and Inventions) (Example 1) 0.2 g of epoxy-modified dimethylpolysiloxane (KF-102 manufactured by Shin-Etsu Chemical Co., Ltd., epoxy equivalent 4000) was mixed by stirring in 260 g of water in a water bath at 40 ° C. did. 15 minutes later,
200 g of potato starch was mixed with stirring. 6.0 g of urea was made into an aqueous solution of about 10% and mixed with stirring. The mixture was subsequently stirred for 4 hours. Then, the starch was filtered off, washed and dried.

The silicon content of the starch obtained in this way was 0.0333%, about 88% of the provided silicon of the starch was fixed by the starch.

The modified starch was wet tested and a small amount of starch was added to the ion exchange water present in the beaker. In this case, the total amount of starch remained floating in water for at least 24 hours.

When the filter paper was dipped in a paste solution having a concentration of 2% and then dried, the filter paper showed hydrophobicity.

When the viscosity was measured at a concentration of 5%, it was 7600 cps (30 ° C.), and it was confirmed that the viscosity was significantly higher than that of the raw material potato starch.

Example 2 Epoxy polyether modified dimethyl polysiloxane (X
-22-3667 (manufactured by Shin-Etsu Chemical Co., Ltd.) (0.2 g) was stirred and mixed in 260 g of water in a water bath at 40 ° C. After 15 minutes, 200 g of potato starch was mixed with stirring. Formamide (6.0 g) was mixed with stirring, and subsequently stirred for 4 hours. After that, the starch is filtered off,
Washed and dried.

When the modified starch was wet tested and a small amount of starch was added to the ion-exchanged water present in the beaker, the total starch amount began to settle immediately and became a clean slurry upon stirring.

When the filter paper was dipped in a paste solution having a concentration of 2% and then dried, the filter paper showed hydrophobicity as in the case of Example 1.

(Example 3) Epoxy-modified dimethyl polysiloxane (molecular weight about 1000)
0) 0.2 g was stirred and mixed in 260 g of water in a 40 ° C. water bath. After 15 minutes, 200 g of corn starch was mixed with stirring. Thiourea 6.0 g was made into an aqueous solution of about 10% and mixed with stirring. The mixture was subsequently stirred for 4 hours. Then, the starch was filtered off, washed and dried.

In the wet test, the same results as in Example 1 were obtained.

The filter paper dried after being dipped in a paste solution having a concentration of 2% was also used in Example 1.
It showed hydrophobicity as in the case of.

(Example 4) 0.2 g of epoxypolyether-modified dimethylpolysiloxane (molecular weight of about 100,000) was added to 260 g of water in a water bath at 40 ° C.
Stir-mixed in. After 15 minutes, 200 g of tapioca oxidized starch was mixed with stirring. 2.6 g of stannic chloride was made into an aqueous solution of about 10% and mixed with stirring. The mixture was subsequently stirred for 4 hours. Then, the starch was filtered off, washed and dried.

When the infiltration test was performed, the starch immediately began to settle as in Example 2.

The filter paper dried after being dipped in a paste solution having a concentration of 2% was also used in Example 1.
It showed hydrophobicity as in the case of.

(Example 5) Epoxy-modified dimethylpolysiloxane (molecular weight about 4000)
Was stirred and mixed in 260 g of water in a 40 ° C. water bath.
After 15 minutes, 200 g of cation-modified starch was mixed with stirring. 15 g of triethanolamine was made into an aqueous solution of about 10% and mixed with stirring. The mixture was subsequently stirred for 4 hours. Then, the starch was filtered off, washed and dried.

When the wetting test was performed, the same results as in Example 1 were obtained.

The filter paper dried after being dipped in a paste solution having a concentration of 2% was also used in Example 1.
It showed hydrophobicity as in the case of.

(Example 6) Epoxy-modified dimethylpolysiloxane (molecular weight about 1000)
0) 1 g was dissolved in 30 ml of n-hexane and mixed with 500 g of potato starch in a mixer, and 15 g of acrylamide was dissolved in 50 ml of water and added to the mixture. The mixture was heated at 40-42 ° C for 4 hours. After cooling, the mixture was poured into water and filtered, washed and dried.

The same results as in Example 1 were obtained for both the wet test and the hydrophobicity of the filter paper.

Example 7 1 g of epoxypolyether-modified dimethylpolysiloxane (molecular weight: about 100000) was dissolved in 30 ml of n-hexane and mixed with 500 g of tapioca starch in a mixer, and 6.0 g of tin acetate was added thereto.
It was dissolved in 50 ml of water and added and mixed. 65-70 ℃ this mixture
Heated for 2 hours. After cooling, the mixture was poured into water and filtered, washed and dried.

In the wet test, as in Example 2, the starch immediately started to settle.

The filter paper dried after being dipped in a paste solution having a concentration of 2% was also used in Example 1.
It showed hydrophobicity as in the case of.

The filter paper impregnated with a paste solution having a concentration of 2% was dried and subjected to the following tests.

1) When you write with a glass marker pen (using toluol as a solvent), the color does not bleed and the back of the paper does not transfer.

2) When one drop of liquid paraffin is dropped on the filter paper, the drop remains as it is and does not penetrate into the paper.

(Example 8) Vinyl-modified dimethylpolysiloxane (molecular weight about 10,000) 1
500 g of corn starch dissolved in 30 ml of n-hexane
Mix in a blender with 50 g of aluminum acetate 4.1 g.
It was dissolved in ml of water and added and mixed. The mixture was heated at 40-42 ° C for 4 hours. After cooling, the mixture was poured into water and filtered, washed and dried.

The same results as in Example 1 were obtained in both the wet test and the hydrophobicity of filtration.

Example 9 10 g of potato starch was gelatinized in 400 g of water at a temperature of 85 ° C. or higher, and then epoxy-modified dimethylpolysiloxane (molecular weight of about 40) was used.
00) 0.1 g was added with stirring, and dimethylformamide 3 g was added. Then, it cooled to room temperature. A filter paper test was conducted on the resulting solution and it showed hydrophobicity.

The entire solution was evaporated to dryness on a rotary evaporator. The 2% strength aqueous solution of the powder obtained then again showed the same hydrophobicity.

(Example 10) 10 g of potato starch was gelatinized in 400 g of water at a temperature of 85 ° C or higher, 0.1 g of epoxypolyether-modified dimethylpolysiloxane (molecular weight 10,000) was added with stirring, and 6 g of trimethylamine was added. Then, it cooled to room temperature.

A filter paper test showed that the filter paper was hydrophobic both after being impregnated with the modified starch solution and after being evaporated to dryness with the powdered solution.

(Comparative Example 1) 0.2 g of epoxy-modified dimethylpolysiloxane (KF-102)
Was mixed with 200 g of potato starch. When a wet test was performed on this mixture, starch immediately began to settle.

Further, the filter paper did not show hydrophobicity even after being dipped in the paste solution having a concentration of 2% and then dried.

Comparative Example 2 Epoxy polyether modified dimethyl polysiloxane (X
-22-3667) 0.2g was mixed with 200g potato starch.

Even when the filter paper was dipped in a paste solution having a concentration of 2% and dried, the filter paper did not show hydrophobicity.

Claims (4)

[Claims] 1. Starch A method for producing a modified starch, which comprises reacting with a modified dimethylpolysiloxane using a compound having an (X = 0 or S) group, an amine, a Lewis acid, a tin salt or an aluminum salt of a carboxylic acid as a catalyst. 2. A modified dimethylpolysiloxane is suspended in water, starch is added to this suspension, then a catalyst is added and the resulting suspension is stirred at temperatures up to 45 ° C. Patent The method according to claim (1). 3. The method according to claim 1, wherein starch and water are heated to form a paste solution, and the modified dimethylpolysiloxane and the catalyst are added to the paste solution. 4. The method according to claim 1, wherein the modified dimethylpolysiloxane and the catalyst are mixed with the starch at a water content of 2 to 50% by using a mixing or kneading device.