JPH02235902A - Cellulose and cellulose derivative particles having xanthite crosslinkage and their production - Google Patents

Abstract

PURPOSE:To facilitate the formation of homogeneous cellulose and cellulose particles having xanthite crosslinkages by reacting porous spherical particles, obtained by dehydrating an emulsion of an aqueous solution of a xanthate of cellulose or its derivative by cooling in a specified water-soluble organic solvent, with an oxidizing agent. CONSTITUTION:A xanthate of cellulose or its derivative soluble in water or an aqueous alkali solution is synthesized, and an aqueous solution thereof is emulsified in an organic solvent containing a thickening polymer to form an emulsion. This emulsion is cooled to a temperature <= 40 deg.C and is poured into an organic solvent which does not dissolve the above cellulose or its derivative and is soluble in water, and the mixture is allowed to cool to room temperature by leaving to form porous spherical particles. These particles are reacted with an oxidizing agent to form xanthite crosslinkages.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to spherical porous particles made of cellulose or cellulose derivatives having xantite crosslinks and a method for producing the same.

<Prior art> For example, granules of cellulose or its derivatives used as carriers for various chromatography such as gel chromatography and ion exchange chromatography are porous particles having a certain shape, especially spherical shape. This is required.

Conventionally, the following method has been cited as an example of producing this type of cellulose particles.

First, cellulose is converted into an organic solvent-soluble derivative, such as cellulose acetate, and this is dissolved in a water-insoluble organic solvent, such as chloroform.

This chloroform solution of cellulose acetate is suspended in water thickened with polyvinyl alcohol (PVA), etc.
Porous beads of cellulose acetate are obtained by stirring and evaporating chloroform while maintaining the temperature above the boiling point of chloroform for a long time.

Next, the acetyl groups are saponified to form cellulose beads.

However, the method of evaporating the solvent by heating takes time.

In addition, cellulose derivatives having heat-sensitive functional groups, such as cyanoethyl cellulose and carbamoyl cellulose in alkali dope, have the disadvantage that they are susceptible to deterioration during the bead synthesis process.

Furthermore, simple cellulose beads have low strength, so it is preferable to add crosslinking.

On the other hand, in the production of cellulose derivative particles, it is common to once create cellulose particles as described above, and then carboxymethylate the surface or introduce other functional groups.

However, subsequent chemical modification does not increase the degree of reactivity and introduces functional groups, resulting in only a portion of the surface being modified.

Furthermore, during the reaction, the surface portion swells and porosity is inhibited.

<Problems to be solved by the present invention> Conventional methods for producing cellulose derivative particles have complicated and time-consuming synthesis routes, making it difficult to form particles of thermally unstable derivatives and to synthesize uniform porous particles. .

An object of the present invention is to provide cellulose or cellulose derivative particles having xantite crosslinks and a method for producing the same, which are free from such drawbacks.

<Means for Solving the Problems> The xantite crosslinked cellulose or cellulose derivative particles of the present invention, as described in claim (2),
Cellulose or cellulose derivative xanthate soluble in water or alkaline aqueous solution is synthesized, the aqueous solution is emulsified by adding it to an organic solvent containing a thickening polymer, and the emulsion temperature is lower than 40°C. Manufactured by forming xantite crosslinks using an oxidizing agent on porous spherical particles obtained by injecting cellulose or cellulose derivative xanthate into a cooled organic solvent that is insoluble and soluble in water and allowing to stand at room temperature. can do.

That is, uniform porous spherical particles can be obtained by cooling and dehydrating an emulsion of an aqueous xanthate solution of cellulose or a cellulose derivative in a water-soluble organic solvent in which cellulose or its derivative is insoluble.

In the present invention, the cellulose derivative used as a raw material for porous spherical particles is not particularly limited, as long as its degree of substitution and substituent distribution are in the water-soluble or alkali-soluble range.

Specific examples include carboxymethyl cellulose,
Carboxyethylcellulose, carbamoylethylcellulose, methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, edylhydroxyethylcellulose, hydroxypropylcellulose, aminoethylcellulose,
Examples include ethyl aminoethyl cellulose, triethylaminoethyl cellulose, and sulfoethyl cellulose.

Any of these cellulose or cellulose derivatives is uniformly dissolved in a 2 to 10% alkaline aqueous solution (Nail{).

Carbon disulfide (CS2) was added to this to the cellulose main chain.
~500 mol% is added, the container is tightly capped, and stirred vigorously until the CS2 is dissolved in the alkaline aqueous solution of cellulose or cellulose derivative, and then the container is rotated at room temperature for 1 to 2 hours.

This reaction yields an orange to yellow colored viscose solution of viscose or a cellulose derivative.

As for the reaction, as previously proposed by the applicant (
(Japanese Patent Application No. 6152603), alkali cellulose may be first subjected to a sulfurization reaction as a starting material to form cellulose xanthate, and then a functional group may be introduced by a known method to form a cellulose derivative.

In this way, the concentration of xanthate is 1-20%, preferably 3-12%, the viscosity is 300-10000 cps,
Preferably, 1500 to 5000 cps of cellulose derivative viscose is prepared.

This viscose is added to an organic solvent thickened with a polymer and emulsified.

For emulsification, 1 to 7% of a nonionic surfactant such as a polyoxymethylene adduct of ricinoleic acid is added to viscose.

Further, the combination of the organic solvent and the polymer for thickening the organic solvent is not particularly limited, but the following table shows preferred representative examples.

The mixing ratio of the viscose solution of cellulose or cellulose derivative and the organic solution of polyimer thickener which becomes the oil phase is viscose:organic solvent=1:0.7 to 1:10 in volume ratio, especially 1:1 to A range of 1:4 is preferred.

This emulsion is stirred at a predetermined stirring speed.

The emulsion temperature may be any temperature below 40° C., and it is preferable to stir the emulsion at a predetermined temperature for 30 minutes or more.

Subsequently, this emulsion was cooled with an organic solvent (-30
(°C to 0°C) and leave to warm to room temperature with gentle stirring.

The mixing ratio of emulsion and organic solvent is 1/0 by volume.
．． It is sufficient if it is 5 or more.

The organic solvent used here is ■) freely miscible with water;
2) mixes freely with the organic solvent used during emulsion preparation, 3) dissolves the thickening polymer, and 4)
Those in which cellulose or cellulose derivatives are insoluble are suitable.

Examples of organic solvents that meet these conditions include methanol, ethanol, and dimethylformamide (for example (1) of combination of thickening polymer and organic solvent).
MP), dimethyl sulfoxide (DMSO), especially methanol, for (2) methanol, l]I'lF
, DMSO, especially methanol, and for (3) acetone are preferably used.

Cellulose derivative particles are formed by injecting and cooling a cooled viscose emulsion into a water-soluble organic solvent in which cellulose derivatives are insoluble, and the water inside the particles is eluted little by little into the organic solvent and dehydrated, resulting in a uniform Porous particles are formed.

Temperature and volume of cellulose emulsion,
It is desirable to tightly control four factors: temperature and volume of the cooled organic solvent.

That is, the porous state of the resulting particles changes slightly depending on the temperature conditions of the emulsion and the organic solvent.

This is because, if the temperature changes, the rate at which water in the particles dissolves into the organic phase and the state of phase separation between the polymer and the solution will also change.

In this case, the heat of mixing and heat of dilution accompanying mixing of the emulsion and the organic solvent must be taken into consideration.

Therefore, by strictly controlling the above four factors, the same porous state can be achieved with good reproducibility.

More specifically, the temperature of the emulsion and the temperature of the organic solvent affect the porosity of the resulting particles.

For example, when an emulsion cooled to -20°C is added to an organic solvent at -20°C, the resulting beads have fine pores on their surfaces.

Conversely, if an emulsion at +25°C is poured into an organic solvent at -20'C, beads with a larger bore size than the former will be obtained.

Next, the organic solvent is removed by decantation, and an oxidizing agent such as hydrogen peroxide, ferric chloride (FeCI3
) or a methanol solution containing iodine, etc., to convert the xanthate groups in cellulose or cellulose derivatives to xantite crosslinking groups.

After the reaction is completed, the supernatant is removed by decantation, and 4% H2SO4 is added thereto for immersion.

After removing the supernatant liquid by decantation again and repeating the operation of adding sulfuric acid to remove impurities such as iron sulfide,
Wash thoroughly with water.

Finally, wash with methanol and ethanol in that order, dehydrate,
By drying, purified cellulose derivative particles having xantite crosslinks are obtained.

The physical properties (swelling, water absorption) of the resulting spherical particles are mainly determined by the type of substituents on the cellulose derivative and, if the degree of substitution is the same, the degree of xantite crosslinking.

Here, xanthite crosslinked particles of cyanethyl cellulose will be explained as an example.

The value indicating how many of the three hydroxyl groups per glucose residue are substituted with cyanoethyl groups is DSx (maximum value is 3), and how many of the three hydroxyl groups per glucose residue are xantite crosslinked. If the value indicating whether the group is substituted is DSy (maximum value is 3), DSX, DSY
is calculated by the following formula from the weights of N and S contained in the beads.

N% - [14x/(162+53x +75y)]XI
OOS%-[64y/(162+53x +75y)I
XIOO In the above formula, X represents DSx, that is, the degree of cyanoethyl substitution, and y represents DSY, that is, the degree of xantite crosslinking.

The relationship between the physical properties (swelling rate and water absorption rate) of the obtained particles and the S weight ratio (ie, degree of crosslinking) is shown in FIGS. 1 and 2.

That is, if the degree of crosslinking is increased, the water absorption rate decreases and the swelling rate also decreases.

This degree of crosslinking can be controlled by the amount of CS2 during the viscose formation reaction.

In the figure, the water absorption rate and swelling rate (volume change rate of particles) were calculated using the following formula for the case where the degree of cyanoethyl substitution D S =0.5 to 0.7.

However, immersion in pure water for 10 minutes, dehydration at 3000 rpm x 5
<Action of the present invention> As the cellulose or cellulose derivative particles having xantite crosslinks of the present invention, any cellulose or its derivative that is soluble in water or an alkaline aqueous solution can be suitably used as a raw material.

Unlike conventional methods, this cellulose derivative has various functional groups introduced in advance and can be used in a delocalized manner. Furthermore, there is no heat treatment step, so there is no risk of deterioration, and it has uniform pores. Spherical particles with a certain degree of strength are obtained.

In particular, the xanthate group in cellulose (-CSSNa
) is susceptible to thermal decomposition, and a large portion of it is destroyed during the solidification process using conventional thermal solidification methods.

However, in the present invention, the formation of spherical particles is achieved through the above-mentioned cooling and dehydration process of viscose with an organic solvent.
Xanthate groups are protected by cooling, and spherical particles with excellent mechanical strength are obtained through the xantite crosslinking reaction.

Moreover, the formation of spherical particles can be carried out in a short time using the simple synthesis route of cooling and dehydration described above.

The physical properties of the particles, such as water absorption and swelling rate, can be easily adjusted by adjusting the amount of carbon disulfide used in the viscose-forming reaction.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Pulp was immersed in a 17.5% aqueous sodium hydroxide solution at room temperature for 1 hour, and then squeezed to 2.8 times the original weight of the pulp.

This was pulverized to form an alkali cellulose powder, which was used in the production of cellulose derivatives.

Put 100g of this alkali cellulose into a glass container,
5.7 g of carbon disulfide (40% molar concentration based on cellulose) was added under reduced pressure, the mixture was tightly stoppered, and the mixture was allowed to react at room temperature for 2 hours.

550 ml of 9% aqueous sodium hydroxide solution was added to the reaction mixture to form a slurry.

Furthermore, 30 g of acrylonitrile [cellulose/acrylonitrile - 1/3 (molar ratio)] was added and reacted for 1 hour to obtain a yellow transparent viscous aqueous solution.

To 500 ml of this viscous solution was added 15 ml of polyoxyethylene ricinoleate as a surfactant.

On the other hand, as an oil layer, a solution in which 90 g of polyvinylpyrrolibin (K-30, manufactured by Hayashi Pure Chemical Industries, Ltd.) and 2000 ml of chloroform were uniformly dissolved was used.

Mix 550 ml of the polymer solution and 770 ml of chloroform thickened with PVP, cool the emulsion solution to -20°C while stirring at a stirring speed of 400 Orpm,
It was held for 30 minutes.

Subsequently, 1980 ml of methanol cooled to -10°C
was gradually added to the solution and allowed to stand at room temperature.

The supernatant liquid was removed by decantation.

Then, FeC13.6H20/CH3COOH/Me
1000ml of oxidizing liquid consisting of OH-(L/l/5) weight ratio
1 was added and stirred for 0.5 hour.

Then, 1% methanol/water (1/5
) washing, filtration, methanol washing, filtration,
Cellulose derivative particles having xantite crosslinks were isolated by ether washing, filtration, and vacuum drying in this order.

Table 1 shows the physical properties of the obtained particles.

Furthermore, electron micrographs (30, 100, and 5000 times magnification) of these particles are shown in FIGS. 3 to 5.

Example 2 Cellulose particles having xantite crosslinks were obtained in the same manner as in Example 1, except that viscose (cellulose content: 12%, sodium hydroxide concentration: 9%, r value -90) was used as the starting material.

Table 1 shows the physical properties of the obtained particles.

Example 3 Hydroxypropyl cellulose (M type manufactured by Nippon Soda Co., Ltd.) was diluted with 9% Na to give a concentration of 5 (W/W%).
Dissolved in OH aqueous solution.

To 200 ml of this solution was added 4.68 g of CS2 (equimolar to cellulose), and the mixture was stirred at room temperature for 2 hours.

Using this hydroxypropyl cellulose solution, cellulose particles having xantite crosslinks were obtained in the same manner as in Example 1.

Table 1 shows the physical properties of the obtained particles.

<Effects of the present invention> As explained above, according to the present invention, cellulose or cellulose derivatives soluble in water or alkaline aqueous solution are used as raw materials, and a material having uniform porosity and mechanical strength can be produced by a simple synthesis route. Cellulose or cellulose derivative particles with excellent xantite crosslinking can be produced.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the swelling rate and the degree of crosslinking for xantite crosslinked particles of cyanoethyl cellulose according to the present invention, and FIG. 2 is a graph showing the relationship between the water absorption rate and the degree of crosslinking of the same as above. Figures 3 to 5 are electron micrographs of cellulose derivative particles obtained in Example 1 (30, 100, 5
000 times).

Claims (2)

[Claims] (1) Cellulose or cellulose derivative particles characterized in that porous spherical particles made of cellulose or a cellulose derivative are crosslinked with xantite crosslinks. (2) Synthesize cellulose or cellulose derivative xanthate that is soluble in water or an alkaline aqueous solution, add the aqueous solution to an organic solvent containing a thickening polymer, and emulsify it.
Porous spherical particles obtained by lowering the emulsion temperature to 40°C or lower, pouring the emulsion into a cooled organic solvent in which the cellulose or cellulose derivative xanthate is insoluble and soluble in water, and leaving it to room temperature. 1. A method for producing cellulose and cellulose derivative particles having xantite crosslinks, the method comprising forming xantite crosslinks using an oxidizing agent.