JPS62149702A - Reversion prevention of cationized starch solution - Google Patents

Abstract

PURPOSE:To obtain a nonreversing cationized starch solution, by production in the presence of benzyl chloride. CONSTITUTION:Three mol% or above, based on starch, sodium hypochlorite and 3mol% or above benzyl chloride are added to a starch slurry, and the starch is epoxidized at a solution temperature kept at about 50 deg.C to decrease its MW. This starch iis gelatinized by the addition of an alkali, and 5-10mol%, based on the starch, aminoalkyl chloride such as 3-chloro-2- hydroxypropyltrimethylammonium chloride is added to the mixture and is reacted at about 50 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to the paper manufacturing industry (= paper strength enhancer or surface coating agent).

The present invention relates to a method for preventing the return of a cationized starch liquid used for sealing.

Returning to the conventional technology refers to a state in which when a starch suspension is heated to gelatinize and then left at room temperature, the paste solidifies into a print-like shape or some gel-like substances are suspended and precipitated in the solution. . The reversion phenomenon is also observed when acid is added to neutralize starch suspension gelatinized with caustic alkali.

Methods to prevent these reversion phenomena include reacting starch with an oxidizing agent such as hypochlorite to oxidatively cleave the main chain of starch and lowering its molecular weight, or reacting formalin with starch sap to reduce glucose groups. A method of acetalizing the hydroxyl group of
Techno I ogyvol, n p330Ac
Academic Press), etc. are known. Furthermore, it has been empirically known that when modified starch is reacted with a patterning agent, the reversion is inhibited, but this has not been sufficient.

It is thought that the return phenomenon is due to crystallization due to the hydrogen bond of glucose + V + forming starch, but the return phenomenon is caused by acetalizing the hydroxyl group of glucose or increasing the agility. It is understood that both of the preventive effects are the result of inhibiting crystallization between glucose. The name of the present invention is based on the above points, and it is effective to prevent crystallization of cationized starch liquid by partially adding a functional group having a bulky structure to glucose forming starch. I thought about this and thought about it repeatedly. The following factors can be cited as factors that should be included in the substance having the above-mentioned return prevention effect.

(a) It has a functional group that can react with starch.

(b) It has a large molecular weight and a long structure, that is, it has a cyclic compound or a long-chain alkyl group.

(c) 611 points is high. Must be liquid. In addition, unreacted substances should be decomposed after the reaction, and the decomposed products should be non-toxic.

(d) Reactants to starch and decomposition products should not have a negative effect on paper.

Since tN powder is composed of glucose units and the reactive group is -CH2QH group at the 6-position, reactions with starch include esterification with R acid, ring-opening etherification with a compound having a glycidyl group, and in the presence of an alkali. An etherification reaction by dehydrohalogenation with an alkyl halide can be considered. This esterification reaction with an internal organic acid cannot be carried out externally, and the etherification of the open member of the glycidyl group is likely to result in an epoxy resin formation reaction between the glycidyl groups.

Therefore, the reaction in an aqueous system is an etherification reaction with an alkyl halide in the presence of an alkali, and the alkyl chloride is contained in the lees. In addition, if we include the requirements that the molecular weight is above a certain level and the boiling point is 100'C or above in consideration of the paper drying process, alkyl chlorides such as octyl chloride or higher, and substances with aromatic rings such as benzyl chloride, etc. . Because this inner long-chain alkyl chloride has low reactivity and is difficult to obtain commercially, we focused on benzyl chloride and conducted extensive research, and as a result, we succeeded in producing a cationized starch liquid that does not have a reversion phenomenon. As will be described later, the paper strength effect of cationic starch that has been converted to benzyl ether with benzyl chloride is the same as that of conventional cationized starch, and benzyl alcohol, which is a decomposition product during the reaction, is not only harmless to paper strength; Starch acts as a preservative.

The currently common method for producing cationized starch paste is to prepare a starch slurry solution, add a sodium hypochlorite aqueous solution to this, and maintain the solution temperature at around 50°C to oxidize the starch and reduce its molecular weight. , and then alkali gelatinization is carried out at room temperature by adding a caustic soda solution. In this process, the amount of sodium hypochlorite used depends on the type of raw starch; for potato starch, it is at least 3 mol% of the starch, and for corn starch (
The second content is 5 mol% or more, and tapioca starch requires 10 mol% or more. If sodium hypochlorite is not used, the viscosity of the w1 paste is high and there are problems in handling, and if the alkaline paste solution is left to stand, it will cause a phenomenon of reversion, such as turning into a pudding. In the cationization step, 3-chlor2 is added to the above alkaline paste solution.
- A method is adopted in which an aminoalkyl chloride such as hydroxypropyltrimethylammonium is added and the reaction is carried out at a temperature of around 50°C. The amount of aminoalkyl chloride added is usually between 5 and 10 moles per starch. The cationized starch solution obtained in this way is strongly alkaline, so it must be neutralized before use, but when an inorganic acid is added to make it neutral, a reversion phenomenon occurs and the gel-like substance becomes suspended. The state will be as follows. This phenomenon can be prevented to some extent by increasing the amount of sodium hypochlorite used to promote oxidation, or by increasing the amount of cationizing agent such as aminoalkyl chloride to 15 molar or more. Although it is possible to do this, it is not always sufficient.However, the effects of sodium boronate are that it causes a decrease in the molecular weight of starch, and increases the coloration of the liquid, which is not desirable from the viewpoint of the effectiveness of the composition agent. The increase in the amount of cationic agents is more than necessary as a cationic agent)i
°, which is uneconomical.

The present inventor has discovered that the reversion phenomenon during neutralization can be prevented by simultaneously adding and reacting benzyl chloride with the cationizing agent in the process for producing the above-mentioned cationized starch liquid. The amount of benzyl chloride added varies depending on the type of starch and the amount of sodium hypochlorite used, that is, the degree of oxidation, but it is possible to effectively prevent the reversion phenomenon by adding 3 or more moles of benzyl chloride, preferably 5 to 10 moles of starch. . However, even with the above use, for example, when 20 mol% or more was added, no particular tendency to improve the reversion prevention effect was observed, but at the same time, the negative influence on the assembly strength was also reduced.

The reaction conditions for benzyl chloride are 50% alkaline and
The conditions for cationization with aminoalkyl chloride after day II are actually the same as those for month Jj. Next to excess by using benzyl chloride above! llI! By using chlorine soda, it is possible to lower the molecular Kl of starch and save more than the necessary amount of cationizing agent.

The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples (2) unless it exceeds the gist thereof.

Reference Example-1 Method for producing standard cationized starch liquid 18 g of corn starch (water content 10%) and 100 ml of distilled water are collected and stirred into a three-lens flask equipped with a stirrer, a thermometer, and a reflux condenser to prepare a starch slurry. The internal temperature was raised to 50°C, 2.9 g of a sodium hypochlorite solution with a chlorine content of 12% (equivalent to 10 mol% of starch) was added, and the reaction was stirred for 15 minutes.

Next, 10 g of 20% NaOH solution (corresponding to 50 mol % of starch) was added and stirred to gelatinize. Next, a 50% solution of 3-chloro2-hydroxypropyltrimethylammonium chloride (hereinafter abbreviated as CTA) (corresponding to 3.71C to starch 10 mol%) was added, and the mixture was reacted at 50°C for 3 hours.

The cationized starch solution thus obtained was subjected to colloid determination with potassium polyvinyl sulfate using toluidine blue as an indicator, and the degree of cationization was measured. As a result, the degree of cationization was 6.0 mol % based on starch.

Reference Examples 2 and 3 Reference Example 2 was started from tapioca starch, Reference Example 3 was started from potatoes, and the reactions were carried out according to Reference Example 1 under the reaction conditions shown in Table 1.

Examples 1, 2, and 3 Each of the following aspects was carried out according to Reference Example 1 under the conditions shown in Table 1. However, benzyl chloride was added and reacted with CTA at the same time. In addition, the alkali it of all alkaline gelatinization L'y is 50 molti.

The effect of the present invention is to neutralize the cationized starch liquid with sulfuric acid.
Evaluation was made based on the presence or absence of a return phenomenon when the temperature was set to 16.0. Return is determined by visual inspection after being left at room temperature for 24 hours after manufacture.

Paper strength test uses LBKP (C, S, F 400ml),
No addition of bread soil - Tsubosuke 5 ('1'A under the conditions of 01/rrt
)' The paper-making ratio tear value was measured using a Pi standard machine.

Table 1: Effects of the present invention Comparing the items of the return phenomenon in the reference example and the example, it is clear that in the examples using benzyl chloride, no return phenomenon was observed, and the effect of benzyl chloride on preventing return is clear. It's Ryo.

Furthermore, the effectiveness of these cationized starch liquids as paper strength agents is not diminished by the use of benzyl chloride.

Claims (1)

[Claims] A method for preventing the return of a cationized starch solution, which comprises adding and reacting benzyl chloride in an amount of 3 mol% or more to the starch during production of the cationized starch solution.