JPS5910800B2 - Anion exchange resin for decolorizing sugar solutions - Google Patents

Description

Detailed Description of the Invention The present invention relates to a crosslinked copolymer obtained by copolymerizing a monovinyl aromatic monomer and a crosslinkable monomer in the presence of a non-crosslinked polymer, more specifically a crosslinked copolymer having an average molecular weight of 6. ×10' to 3×10
The present invention relates to an ion exchange resin which has an excellent ability to decolorize a sugar solution by treating a crosslinked polymer obtained by polymerization in the presence of a non-crosslinked polymer of No. 5.

-Generally, a vinyl monomer and a crosslinkable monomer are subjected to suspension polymerization to obtain a particulate polymer, and various functional groups are introduced into the polymer to make it insoluble.
It is well known to produce infusible particulate ion exchange resins.

It is also known that a so-called porous anion exchange resin with a low degree of crosslinking is used as a decolorizing resin. That is, a monovinyl monomer containing a small amount of crosslinkable monomer is polymerized in the presence of a catalyst, and an anion exchange group is added to the resulting crosslinked polymer, which is insoluble and infusible but extremely swellable, through various processes. The ion exchange resin into which the ion exchange resin has been introduced has a high water content and is therefore suitable for adsorbing pigments as a porous resin, and is used in large quantities in decolorizing and purifying processes in various fields. By the way, it has been found that there is a nearly proportional relationship between the porosity (actually expressed as water content) of resins produced by this method and their ability to adsorb fairly large molecules such as dyes. However, the porosity of ion exchange resins produced by this conventional method is strictly controlled by the size of the porosity of the network structure within the molecule, so it is impossible to increase the porosity beyond a certain level from a practical standpoint. Yes, there is a natural limit to the size of the pores. In addition, increasing the water content beyond a certain level using this method makes it difficult to pass the liquid to be treated through the resin layer due to a decrease in physical strength and an increase in the difference in swelling and contraction of the resin during liquid passage and regeneration. It is something to do. Therefore, with a resin having a simple gel structure produced by this method, it cannot be expected that the decolorizing ability will be increased beyond a certain level. However, the industrially necessary decolorization and purification is rarely performed on extremely large molecules.

Therefore, tuna reticular type (MR type) ion exchange resins, which are considered to have extremely large porosity and distribution, do not necessarily have high decolorizing ability. For example, in the process of decolorizing and refining sugar, the harmful pigments present in the crude sugar have molecular weights ranging from several hundred to several directions, and are composed of a wide variety of different substances.

Therefore, by treating a sugar solution with a low K color value that has been pretreated with activated carbon, etc. using a gel-type ion exchange resin using a conventional method, the sugar solution will be considerably decolorized and a clean sugar solution will be obtained. However, when a sugar solution with a high color value without such pretreatment is passed through this gel type resin, the decolorization rate becomes extremely poor. On the other hand, MR type ion exchange resin is
When treating a sugar solution with a high color value, the decolorization property is quite good, but the decolorization property is relatively poor when treating a sugar solution with a low color value that has been pretreated. Therefore, in order to remove these complex pigments, it is thought that the resin must have a continuous porosity over a wide range and also have the same porosity as conventional gel-type resins. The object of the present invention is that there is an upper limit to the porosity of gel-type ion exchange resins produced by conventional methods, and that MR-type ion exchange resins produced by special methods have excessive porosity, which is disadvantageous for decolorization and purification. This is an anion exchange resin that overcomes both of these problems and has even better decolorizing performance.

More specifically, a certain amount of a linear polymer having an average molecular weight within a certain range is added to a vinyl aromatic monomer and dissolved uniformly, and a crosslinkable monomer is added to this to form a uniform solution. This mixture is further polymerized to produce a basic polymer, which is then treated to introduce anion exchange groups, resulting in an ion exchange resin with properties most suitable for decolorization. According to this, it is possible to compensate for the drawback that the conventional porous resin made of gel-type resin has poor physical strength. In the present invention, a crosslinked copolymer is synthesized in the presence of a certain amount of a linear polymer having an average molecular weight within a certain range. It is essential that the vinyl aromatic monomer and the crosslinkable monomer be well and uniformly dissolved.

However, any polymer can be used as long as it dissolves uniformly, but generally speaking, monovinyl monomers used in crosslinked copolymers, i.e. polystyrene, are separately polymerized to form linear polymers. is the easiest to use. It is already known, for example, in Japanese Patent No. 237102, that a crosslinked copolymer can be created by coexisting such linear polymers. This is a method for manufacturing an exchanger, and on the other hand, in the present invention, it is essential to have numerous fine cracks.

As shown in the Examples, a crack-free resin has a very low decolorizing effect and is not practical as a decolorizing resin. The feature of the present invention is that the internal structure of the resin itself has properties suitable for decolorization, rather than focusing on such external properties. The partial polymer used in Japanese Patent No. 237102 is one in which a vinyl monomer is partially polymerized in advance to form an X-crosslinked copolymer containing the vinyl monomer.
No. 22514 also describes that a crosslinked polymer can be obtained by incorporating a similar partial polymer. In response to these problems, the present inventors found that simply coexisting and polymerizing such polymers does not necessarily yield a resin with excellent decolorizing properties, and that coexistence of a certain amount of linear polymers having a molecular weight within a specific range is not guaranteed. It was through this process that I discovered an anion exchange resin that always had excellent decolorizing properties. The molecular weight range of this linear polymer is 6 x 104 to 3 x 105, and the coexistence amount is 1.
It is essential that it be between 0% and 10.0%. Although the molecular weight and amount of the partial polymers shown in the Japanese patents and US patents mentioned above are not known, the portions obtained by partial polymerization in an inert gas without catalyst are particularly important. The molecular weight of a polymer is always 6×10 regardless of the amount produced.
It is normal that it is 5 or more. Even if a small amount of a partial polymer having such a high molecular weight is allowed to coexist and polymerize, the porosity of the resulting resin is extremely large, resulting in the above-mentioned MR.
It has properties similar to mold resin, and its decolorization performance is poor. On the other hand, the linear polymer in the present invention is not produced by a partial polymerization method, but is produced by a bulk polymerization method or a suspension polymerization method such that the linear polymer has a desired molecular weight by adjusting the catalyst amount. , this is obtained and later added to the vinyl monomer and dissolved. Therefore, in the case of a cross-linked polymer in which a polymer such as a partial polymer coexists, the cross-linked polymer is opaque and cloudy before ion exchange groups are introduced, whereas the cross-linked polymer of the heather invention is gel-type. The transparency is high, almost the same as in the case of resin. This fact indicates that there is a difference in the internal structure of the resin between the two. The monovinyl aromatic monomers used in the present invention include the following.

Styrene, vinyltoluene, vinylxylene, α-
These include methylstyrene, β-methylstyrene, vinylnaphthalene, vinylalkylnaphthalene, etc. Examples of the crosslinkable monomer include the following. i.e. divinylbenzene,
These include esters of unsaturated acids and unsaturated esters of acids such as divinylpyridine, divinyltoluene, divinylnaphthalene, diallyl phthalate, and ethylene glycol diacrylate. The ratio of monovinyl aromatic monomer to crosslinking monomer can vary widely within the scope of the invention depending on the intended use of the polymer.

As mentioned above, the content ratio of the linear polymer necessary for the purpose of the present invention is 1.0 to 10.0% with respect to the mixed solution of the monovinyl aromatic monomer and the crosslinkable monomer, but within this range. can be selected arbitrarily depending on the purpose.

If the amount of this linear polymer exceeds 20%, the decolorizing ability of the final product will decrease, and if the basic polymer is made by suspension polymerization, monovinyl aromatic monomers containing the linear polymer will be used. The viscosity of the mixture of polymer and crosslinkable monomer increases significantly (generally, even a small amount of high polymer increases the viscosity of the solution significantly), making it extremely difficult to create particles of an appropriate size. Therefore, when using the partial polymerization method, the degree of polymerization is generally very high, so even if the monomer mixture is used in a small amount, the viscosity of the monomer mixture becomes high, making it difficult to obtain a particle size suitable for an ion exchange resin. When trying to obtain particles having a 100% by suspension polymerization method, it is quite difficult, and the increased viscosity is lowered by diluting with a solution unrelated to the polymerization, and then the polymerization is carried out. Regarding the linear polymers used in the present invention, for example, D.H. Johnsson, A.
．． V. A polymer having a degree of polymerization falling within the above range can be easily obtained by adjusting the amount of the polymerization catalyst according to the method described in vol. 74, p. 953 of the Journal of the American Chemical Society by J. Toborski.

The obtained linear polymer was weighed and added to the monovinyl monomer solution, and the crosslinkable monomer was further added and dissolved uniformly.
Furthermore, a polymerization catalyst is added, and an aqueous solution containing a suitable dispersant such as methylcellulose or Popal is gently added from the bottom of the monomer mixture layer, and then the stirring speed is adjusted to obtain an appropriate particle size. Then, polymerization is carried out at a polymerization temperature of 40 to 100°C, preferably 700 to 90°C, while stirring the whole. The polymerization catalyst used in this case is, for example, an organic peroxide such as benzoyl peroxide or lauroyl peroxide,
Also suitable are organic azo compounds such as azobisisobutyronitrile. Next, after drying the basic polymer thus obtained, a haloalkylation reaction is carried out by a conventional method. That is, this polymer is directly added to a haloalkyl ether, preferably chloromethyl ether, without performing any extraction operation, and after sufficient swelling, a Friedel-Crafts type catalyst is added thereto for reaction. At this time, this reaction can also be carried out by adding a solvent unrelated to the reaction to the haloalkyl ether. The linear polymer in the spherical polymer is
During this haloalkylation reaction, a considerable amount is extracted.
This is confirmed by the fact that, after the haloalkylation reaction is complete, when water is added to decompose the catalyst and excess alkyl ether, a thin film is formed all over the surface of the water layer. In this case, it is very difficult to extract high molecular weight materials such as those produced by partial polymerization, and the formation of effective porosity is incomplete. Matako
As the Friedel-Grafts type catalyst used in this invention, anhydrous aluminum chloride, tin chloride, zinc chloride, iron chloride, etc. are used, but in the present invention, anhydrous zinc chloride is most preferred. When aluminum chloride or tin chloride is used as a catalyst in the haloalkylation reaction process, three-dimensional cross-linking occurs, and at this time, the linear polymers in the basic polymer participate in this bonding reaction. Therefore, it is easily included in the resin structure without being eluted. This has unfavorable consequences for the production of various porosity according to the present invention. Therefore, it appears that anhydrous zinc chloride, which hardly causes this bonding reaction under normal conditions, is the most preferable catalyst. Finally, after thoroughly washing the haloalkylated product thus obtained with water, anion exchange resins having various basicities can be obtained by adding and reacting various amines in a conventional manner.

That is, by reacting a tertiary amine such as trimethylamine or dimethylethanolamine, a strong basic resin having a quaternary ammonium salt type can be converted into a tertiary resin by reacting a secondary amine such as dimethylamine or monomethylethanolamine. A weakly basic resin having a secondary amine can be obtained by reacting an amine type medium basic resin with a primary amine such as monomethylamine. Since the linear polymer into which amino groups have been introduced has high water solubility, it may be extracted from the spherical polymer by washing with water. When the anion exchange resin for decolorizing sugar solution produced in this way is dried to remove moisture, or when immersed in glycerin, etc., which has a strong dehydrating effect, the entire particle becomes almost completely transparent. is observed.

Compared to a simple gel-type resin produced by a conventional method, especially when the molecular weight of the linear polymer is a little larger, the transparency is somewhat lowered.
However, in the method of polymerizing including the partial polymer mentioned above,
It is observed that the clarity of the final product is significantly reduced.
The anionic exchange resins described above have the ability to decolorize a wide range of dyes with various molecular weights, but they are also industrially useful substances whose molecular weights range from several hundred to several thousand. It also adsorbs substances very well.

Production Example 1 Styrene treated with a dilute aqueous caustic soda solution was separated from the aqueous layer, then dehydrated with calcium chloride and distilled under reduced pressure.

0.037 mol/t of benzoyl peroxide to this styrene
and 0.020 mol/t were added separately and polymerized at 60° C. for 26 to 50 hours in a nitrogen stream. The viscosity average molecular weight of the linear polymer thus obtained was 714×104 for the former.
The latter was 1.10×105. This almost completely agrees with the value calculated from the formula shown in Journal of the American Chemical Society, Vol. 74, p. 938. Next, linear polystyrenes having various viscosity average molecular weights were obtained under the same conditions using azohisisoptylonitrile instead of benzoyl peroxide.

In order to facilitate explanation in the following examples, sample numbers are attached to these samples to indicate average molecular weights. A: 4B3×10
4, B: 757 x 104, C: 122 x 105 D: 1.
68×105, B: 230×105 The molecular weight of the partial polymer obtained by polymerizing in the same nitrogen stream without adding any catalyst at 80° C. for 12 hours was 7.1×105.

Production Example 2 Molecular weight of the linear polymer synthesized in Production Example 1: 114×
12.5 of 104? , styrene 236.7y and commercially available divinylbenzene (purity 56.2%) 13.3? Add to the mixture and stir to dissolve uniformly.

Once completely dissolved, 1.75 t of benzoyl peroxide is added as a catalyst and stirred for a while to dissolve.
To this, 600 d of an aqueous solution containing 0.1% polyvinyl alcohol as a dispersant was gently added from the bottom of the monomer mixture layer, and when the addition was complete, the whole was stirred to form oil droplets of an appropriate size. Adjust the stirring speed to . Polymerization proceeds while maintaining the temperature at 90°C. After about one and a half hours, the temperature is raised to 98°C to complete polymerization, and the resulting bead polymer is thoroughly washed with water and dried at 125°C.
This bead polymer is white and almost transparent. 106 tons of beads thus obtained were mixed with 200 tons of chloromethyl ether. After the beads were sufficiently swollen, 60 y of anhydrous subsalt chloride was added under stirring, and the chloromethylation reaction was carried out at a temperature of 45° C. for 6 hours.

After the reaction is complete, the contents are cooled, water is added to decompose the catalyst, and the contents are washed thoroughly by repeated siphoning and water washing. Add trimethylamine aqueous solution (
Add 200 d (concentration 30%) and keep at room temperature to carry out the amination reaction. After the amination reaction is completed, ethylene dichloride is distilled off together with water by heating, and then thoroughly washed with water. The resulting product has numerous small cracks on its surface, but the spherical particles themselves are not very soft. If this is dried,
It is observed that when immersed in glycerin, the entire particle becomes almost completely transparent. The water content of the obtained ion exchange resin was 63.0%, and its neutral salt decomposition capacity was 0.96 meq/me. On the other hand, gel-type resins can be synthesized by conventional methods simply by polymerizing a mixture of styrene and divinylbenzene in the same manner as above without adding any linear polymer, and then performing chloromethylation and amination. A gel type anion exchange resin can be obtained. The resulting product has numerous small cracks on the surface as in the case above, but the particles themselves are rather soft.
When dried or immersed in glycerin, the entire particle becomes completely transparent. The water content of this resin is 60.2%, and its ion exchange capacity is 0.2%/d.
It was 98 milliequivalent. Example 1 The decolorizing performance of each resin synthesized using the linear polymer obtained in Production Example 1 and the content shown in the following table according to the method in Production Example 2 was examined.

The method for the decolorization test is to mix 1.0Kf of raw sugar (raw sugar) containing various untreated pigments and 1.3Kf of granulated sugar with 1.5Kf of water.
The solution obtained by dissolving the sugar in water and adjusting the sugar concentration to 59.5% was used as a decolorizing solution.

300 ml of this solution was passed through a column filled with 50 d of resin at 70 to 75° C., and the decolorization rate when treated at a space velocity of 5 to 6 was measured and calculated using a spectrophotometer. Furthermore, simple gel-type resins made by conventional methods, commercially available MR-type resins (trade name:
Comparative tests were also conducted on Amberlite IRA-900'' and a resin obtained by a partial polymerization method. The linear polymer coexisting as described above must have a molecular weight of 60,000 or more, but those with a significantly large molecular weight such as partial polymers are unsuitable, and if the coexisting amount exceeds 10%, the porosity will increase. It was confirmed that this resulted in an excessive amount of water and was unsuitable for decolorization. Example 2 In Production Example 1, the linear polymer having an average molecular weight of 7.14 x 104 and the polymer having a molecular weight of Z1 x 105 obtained by the same partial polymerization method were each co-existed at 7.0%. The crosslinked polymer obtained was subjected to chloromethylation and amination with trimethylamine in the same manner as in Production Example 2 to obtain an anion exchange resin.

The former has numerous small cracks on the resin surface and is highly transparent, while the latter has almost no cracks and is completely opaque. When both were subjected to a decolorization test using the same sugar solution as in Example 1, the decolorization rate of the former was 94.1%, but the decolorization rate of the latter was only 69.2%. Example 3 A linear polymer with a molecular weight of 1.04 x 105 was 4.6
A mixture of styrene and divinylbenzene containing 7% (actual divinylbenzene content 3.5%) and a mixture of styrene and divinylbenzene containing 5.6% of the same molecular weight 6.81 x 104. Production Example 2
Anion exchange resins were obtained by chloromethylation and amination with trimethylamine in the same manner as in .

A decolorization experiment was conducted on these two resins and a gel type anion exchange resin (the most commonly used anion exchange resin) obtained by a conventional method under the following conditions. Fill it with a sugar solution having a color value as shown in the table below at a temperature of 70°C at a space velocity of 10 and add 4 of the resin amount.
Pass 0 times the amount of liquid. After that, add 200r of 10% aqueous solution of table salt.
The resin is regenerated at a temperature of 70° C. at the regeneration level of NaCl/t-resin. This is called one cycle. Using this method, the decolorization test was repeated for 40 cycles for the three resins, and the results are shown in the following table. The former two are each Y by the method of the present invention.
, Z, and the conventional method is X. The color value of the sugar solution is quite high. Each numerical value is expressed as a decolorization rate (4).

*The color value of the sugar solution is - of the transmittance (T) at 530 mμ.
It was expressed as 10gT.

The blank column for decolorization rate (5) indicates that the cycle test was performed but the decolorization rate was not measured. After 34 cycles, each resin was subjected to regeneration treatment using a hypochlorous acid sorter solution. Example 4 Next, resins Z and X in Example 3 were compared in decolorizing ability for a sugar solution with a relatively low color value.

Approximately 100 cycles were repeated under exactly the same conditions as in Example 3 except that the color value of the sugar solution was different. The results are shown in the table below. However, the numerical value of the decolorization rate shows the average value for each 10 cycles. Each numerical value is expressed as a decolorization rate (4).

*The color value of the sugar solution is shown by converting the transmittance (T) at 420 mμ into the Stanma color value.

Example 5 The results of determining the failure rate of the resins after the decolorization test for the three test resins X, Y, and Z in Example 3 are as follows. The amount of broken resin that passed through a 50-mesh sieve was measured after the cycle test, excluding the resin particles that passed through, and was expressed as a ratio to the total amount of resin.

As a result, the resin according to the present invention was found to have improved strength against physical damage, albeit slightly.

Claims (1)

[Claims] 1 Monovinyl aromatic monomer (I) and crosslinkable monomer (
II) coexists with polystyrene having an average molecular weight in the range of 6 x 10^4 to 3 x 10^5 at a ratio of 1.0% to 10.0% based on the mixed amount of (I) and (II). Please,
An anion exchange resin for decolorizing a sugar solution, which is obtained by suspension polymerizing in an aqueous medium to produce a uniform granular crosslinked polymer, which is then haloalkylated and further aminated.