JPS59155414A - Graft copolymer of high-molecular polysaccharide and its synthesis - Google Patents

Abstract

PURPOSE:To obtain a graft copolymer of high-viscosity, high-molecular polysaccharide which has improved heat resistance and can be used stably over a wide temperature range, by graft-copolymerizing a water-soluble acrylic monomer with high-molecular polysaccharide in a specified state. CONSTITUTION:A colloidal aqueous dispersion of a high-molecular polysaccharide (e.g., a polyelectrolyte obtained by the action of bacteria such as Xanthomonas on glucose) is heated to a temperature >=60 deg.C to bring the dispersion into a state of a molecular dispersion. At least one water-soluble acrylic monomer [e.g., a compound of the formula (wherein R is H or methyl, and R' is amino, monomethylamino, or the like)] is graft-copolymerized with the high- molecular polysaccharide in the above state in the presence of a persulfate (e.g., ammonium persulfate) to obtain the desired graft copolymer of high-viscosity, high-molecular polysaccharide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel high-viscosity polymeric polysaccharide graft copolymer comprising a grafted polymeric polysaccharide having improved heat resistance and a method for producing the same.

Xanthomonas campestris (Xan
xanthan gum, which is obtained by the action of f. homonas campestris, and the same
tica), Azotobacter indicum (azoto
It is well known that a water-soluble acrylic monomer is graft-copolymerized to a polymeric polysaccharide such as a polymer electrolyte obtained by the action of a water-soluble acrylic monomer (
For example, see British Patent No. 1,517,492). Utilizing its high viscosity, it is used as a food additive, crude oil recovery agent, etc.

Conventionally, this graft copolymer of high-molecular polysaccharide has been produced by a method of reacting an amount of a redox catalyst such as a cerium salt with an acrylic thread. Graft copolymers have the disadvantage that when their aqueous solutions are heated to a temperature of about 60° C. or higher, they denature and cause a rapid decrease in viscosity, so they are subject to limitations regarding usage conditions.

The present inventors have conducted intensive research to overcome the drawbacks of conventional polymer polysaccharide graft copolymers and to develop a highly viscous polymer polysaccharide graft copolymer that can be used stably over a wide temperature range. As a result, we discovered that a polymeric polysaccharide obtained by graft copolymerizing a water-soluble acrylic monomer under a specific condition surprisingly shows little viscosity decrease even at temperatures above 60°C.Based on this knowledge, we developed an invention. I arrived at the eggplant.

That is, the present invention provides a highly viscous polymeric polysaccharide graft copolymer with improved heat resistance, which is composed of a molecularly dispersed polymeric polysaccharide grafted with an acrylic monomer.

The uninvented highly viscous polymeric polysaccharide graft copolymer is produced by first heating a colloidal aqueous dispersion of a polymeric polysaccharide to a temperature of 60° C. or higher to form a molecularly dispersed state, and then preparing it in the presence of a persulfate. It can be produced by graft polymerization of water-bathable acrylic monomers.

The polymeric polysaccharide graft copolymer thus obtained is a highly viscous substance with hydrophilic properties, and is stable without causing a significant decrease in viscosity even when heated to 60° C. or higher. This is because the fine structure of polymer polysaccharide graft copolymers produced by conventional methods collapses when heated and loses viscosity, but by graft copolymerization in a molecularly dispersed state, the fine structure This is thought to be because it is stably protected and does not disintegrate even when heated.

The polymeric polysaccharide used in the present invention can be arbitrarily selected from those used as substrates in conventional methods. Examples of such substances include polymer electrolytes obtained by reacting evaglucose with bacteria such as Xanthomonas campestris, Erwinia tahitiani, and Azotonokhuta indicum.

In addition, the water-soluble acrylic monomer to be graft-copolymerized with this polymeric polysaccharide is, for example, the general formula % [In the formula, R is a hydrogen atom or a methyl group, and the formula is an amino group, a monomethylamine group, a dimethylamino group, Monohydroxyethylamine group, -NHC(OH5)20H,,5o3
H group or -NHC(OH3) 2 CH2SO3Na group] may be used. These acrylic monomers may be used alone or in combination of two or more.

Graft copolymerization of acrylic monomers to polymeric polysaccharides needs to be carried out in the presence of a persulfate catalyst,
Peroxide and azobisisobutyronitrile, which are commonly used in the copolymerization of acrylic monomers, are not suitable because they not only do not allow the graft copolymerization to proceed smoothly but also produce water-insoluble gel-like substances. be. As the persulfate, sodium persulfate or potassium persulfate may be used, and ammonium persulfate is particularly preferred.

In this graft copolymerization, first, a high molecular weight polysaccharide is dissolved in water to prepare an aqueous colloidal dispersion solution, and this solution is
By heating the colloidally dispersed polymeric polysaccharide to a molecularly dispersed state by heating it to a temperature of 0°C or higher, the polymer polysaccharide is kept in that state in the presence of a persulfate catalyst. The acrylic monomer 2 graph I/polymerization is important.

The concentration of the aqueous polymeric polysaccharide solution is not particularly limited, but an aqueous solution concentration of about 3 to 5 mmol of the repeating structural unit of the polymeric polysaccharide is advantageously used. The amount of the acrylic monomer used for grafting is selected depending on the desired ratio of grafting components, but it is usually used in the polymerization system in a range of 5 to 500 mmol. Furthermore, the amount of filtered sulfate used as a catalyst is about 0.1 to 1 J mol, and the proportion of 0.1 to 3 mol of the filtered sulfate is usually selected depending on the total amount of monomer. You can increase or decrease it as appropriate.

In the uninvented method, although it is not essential to completely exclude carbon atoms from the polymerization system and to isolate reaction-interfering factors, it is necessary to use a polymeric polysaccharide aqueous solution, a sucrose, and usually water. Regarding the aqueous solutions of persulfates that are dissolved and used, the air (oxygen) in each container is preferably replaced with an inert gas, such as nitrogen gas.

The graft polymerization reaction is generally carried out by stirring an aqueous polymer polysaccharide solution to which a catalyst has been added while maintaining the temperature at 60°C or higher, and then adding an acrylic monomer. You can also do it. When graft polymerization is carried out in this way, for example, 2
It is possible to obtain a graft copolymer of a high molecular weight polysaccharide at a high polymerization rate in a short time of about 0 minutes to 3 hours.

Further, the aqueous solution of the graft copolymer of high-molecular polysaccharide prepared in this way is poured into a large amount of methanol that is being stirred, and the copolymer ? It can be separated as a fibrillar precipitate.

During this precipitation, the pH of the copolymer water bath solution is adjusted to 6 or less by adding, for example, about 1 liter of hydrochloric acid water, or the pH is adjusted to 8 or more with an alkali hydroxide water bath solution. , can be precipitated by focusing in methanol, and by such pH adjustment, different cations can be bound. The precipitated graft copolymer is separated by appropriate means and dried by a method.

Hereinafter, the special rinsing material of the present invention will be explained in more detail with reference to Examples.

Example 1 400 flasks of deionized water were placed in a 500-meter four-eye flask equipped with a gas inlet pipe and a gas discharge pipe, and equipped with a thermometer, raw material inlet, and stirrer, heated to 72°C, and then heated to 72°C. While stirring, add powdered xantango b, 31' (
! - and introduced nitrogen gas for 1 hour to prepare an aqueous solution of molecularly dispersed polymeric polysaccharide.

Separately, ammonium persulfate O, ], 14. ! 1OOrn that dissolved 9! An aqueous solution of , was prepared in advance by replacing light with nitrogen gas, and added to the above-prepared aqueous solution cooled to 45°C for 20 minutes (stirred and then gradually warmed. The temperature of the aqueous solution was 60°C). At the stage when 3.55 g of acrylamide was dissolved in Y water and thoroughly purged with nitrogen gas, a 100-water bath solution was added to the flask, continued to be heated while stirring, and graft polymerization reaction was carried out at a temperature of 72°C for 30 minutes. I let it happen.

The obtained graft copolymer water bath solution was divided into two parts, one part was adjusted to pHy 2 to 3 by adding 1N hydrochloric acid solution dropwise thereto, and the other part was adjusted to pHxs to 9 by adding 1N sodium hydroxide.

Next, each pH-adjusted solution was poured into a large amount of methanol while being stirred, and a fibrillar graft copolymer of high-molecular-weight polysaccharide was precipitated from each solution.

In preparing this graft copolymer, 1.8 g of acrylamide was added as a monomer to be graft polymerized.
The procedure was carried out in the same manner except that a 00-water bath solution was used, and the resulting graft copolymer was subjected to precipitation treatment by adjusting the pH of the water bath solution to 8 to 9.

The fibrillar precipitates of each were separated and dried under reduced pressure. The yields of the obtained graft copolymers were all 90~
The weight was within the 96 weight range.

When we measured the dependence of the viscosity on the velocity gradient of the obtained aqueous solutions of each graft copolymer, we found that the dependence was small (,
In particular, the transition due to the collapse of the microstructure, i.e. the temperature 60
There is no rapid viscosity reduction phenomenon near °C (therefore, the state of molecular dispersion is maintained independent of temperature), and it is essentially different from high-molecular polysaccharides or their conventionally known acrylic graft copolymers. It was confirmed that different copolymers were formed.

Furthermore, when this graft copolymer was produced using a broth-like polymeric polysaccharide, a completely similar acrylic graft copolymer of a polymeric polysaccharide could be obtained.

Comparative Example Acrylic monomer of Example 1 3.55.9/100-
When using an aqueous solution, the same procedure was carried out using benzoyl peroxide or azobisisobutyronitrile as a catalyst instead of ammonium persulfate.

Sonofi results and graft reaction yields are both 50~
It was low (about 70%), and in addition, the product contained a large amount of non-M gel-like structures (for example, it was impossible to filter with a 5μ Millipore filter).

Examples 2 and 3 In Example 1, acrylamide was 3.5! In place of V, acrylamide 5.7.9 and 2-acrylAεB2
- mixture with 4.6 g of sodium methylpropanesulfonate (Example 2) or 2- with 3.5.9 g of acrylamide
Fibrillar high-molecular polysaccharide graft copolymers were obtained in the same manner except that a mixture with 11.5.9 of storium acrylamide-2-methylpropanesulfonate (Example 3) was used.

Their yield was 90-94% by weight.

Concentration of polymer polysaccharide used for graft polymerization: 5000 ppm
The viscosity of the aqueous solution at 20°C is 1,600C, p
, whereas the viscosities of aqueous solutions of the same concentration of each graft copolymer obtained by the above graft polymerization are 1.200 C, p, (Example 2) and 1.100 C, respectively.
, I), (Example 5), the graft copolymer according to the invention has less dependence on the velocity gradient and is stabilized against heat dispersed in the molecules ↓°() in an aqueous solution. Understand that.

Claims (1)

[Scope of Claims] 1. A highly viscous polymeric polysaccharide graft copolymer with improved heat resistance, which is composed of a molecularly dispersed polymeric polysaccharide grafted with a water-bathable acrylic monomer. 2. A colloidal aqueous dispersion of a polymeric polysaccharide is heated to a temperature of 60°C or higher to form a molecular dispersion state, and then a water-soluble acrylic yarn monomer is graft copolymerized in the presence of a persulfate catalyst. A method for producing a highly viscous polymeric polysaccharide graft copolymer with improved heat resistance. 6. The method according to claim 2, wherein the persulfate catalyst is sodium persulfate, potassium persulfate or ammonium persulfate.