CN101830990A - Instant hydroxypropyl methyl cellulose ether and preparation method thereof - Google Patents

Abstract

The invention discloses instant hydroxypropyl methyl cellulose ether and a preparation method thereof. The preparation method comprises the following steps of: performing alkalization, etherification, neutralization, solvent recovery, washing and centrifugation on cellulose purified cotton; in a drying process through a shaftless auger, spraying glyoxal serving as a cross-linking agent into the shaftless auger, wherein 100 kg of glyoxal serving as the cross-linking agent is sprayed into every 660 kg of cellulose purified cotton; fully stirring and reacting the mixture; and drying the mixture in a flash dryer to obtain the instant hydroxypropyl methyl cellulose ether with 100 percent dispersity, wherein the glyoxal serving as the cross-linking agent is prepared by mixing and stirring 35 percent glyoxal and soft water with the hardness less than 0.03g/L in a ratio of 1:8. On the premise that other indexes meet requirements, the instant hydroxypropyl methyl cellulose ether is not agglomerated after being dissolved, has a high dispersing and dissolving speed, overcomes constraints in practical application and expands application field.

Description

Instant hydroxypropyl methyl cellulose ether and preparation method thereof

Technical field

The invention belongs to the macromolecular material field of fine chemical, especially the preparation of hydroxypropyl methyl cellulose ether.

Background technology

Along with the development of Chinese national economy, the purposes of instant hydroxypropyl methyl cellulose ether is more and more wider, and annual requirement constantly increases.Can be used as emulsifying agent, thickening material, dispersion agent, stablizer, sizing agent, membrane-forming agent, water-holding agent etc., be applied in industrial circles such as oil, weaving, daily use chemicals, cigarette, papermaking, building, food, medicine.

Traditional hydroxypropyl methyl cellulose ether production technique is: with the Mierocrystalline cellulose purified cotton with the sodium hydroxide generation sodium cellulosate that alkalizes under certain conditions, carry out etherificate with propylene oxide, methyl chloride again, reaction under certain condition generates hydroxypropyl methyl cellulose ether, finally obtains the exsiccant finished product by neutralization, recovery solvent, washing, drying again.The deficiency that this technology exists is: dispersion effect is bad in actual applications to produce hydroxypropyl methyl cellulose ether, unites easily, and dissolving is slow, and serious bundle has been made an appointment with Application Areas.As in building materials paste putty, the indissoluble of uniting during with water dissolution can't normally use.Therefore, when practical application, need dissolving in advance, strengthened difficulty of construction and engineering time thereof like this.

Summary of the invention

The objective of the invention is to solve existing hydroxypropyl methyl cellulose ether and be difficult for dissolving, unite and the technical problem of dispersion effect difference easily, a kind of preparation method of instant hydroxypropyl methyl cellulose ether is provided.

For achieving the above object, technology of the present invention comprises the Mierocrystalline cellulose purified cotton with the sodium hydroxide generation sodium cellulosate that alkalizes, use propylene oxide again, methyl chloride carries out etherification reaction and generates hydroxypropyl methyl cellulose ether, again by neutralization, reclaim solvent, washing and drying process, it is characterized in that, material is after washing is centrifugal, do not entering in the exsiccant process by there being the axle auger, in having the axle auger, do not spray into the linking agent oxalic dialdehyde, require every 660Kg Mierocrystalline cellulose purified cotton to spray into linking agent oxalic dialdehyde 100Kg, make its abundant stirring reaction, enter flash dryer again, obtain dispersity and be 100% instant hydroxypropyl methyl cellulose ether.

Described linking agent oxalic dialdehyde is to be stirred according to 1: 8 mixed less than the soft water of 0.03g/L with hardness by 35% oxalic dialdehyde to form.

Reaction principle is: with oxalic dialdehyde aldehyde radical (CHO) carbonyl compound with ether of cellulose changes acetal into, after reaction is finished, obtains structural formula instant hydroxypropyl methyl cellulose ether same as the prior art.

The instant hydroxypropyl methyl cellulose ether of the present invention's preparation has been introduced aldehyde radical in preparation process, all contain carbonyl in aldehyde and the ketone, and carbonyl is quite active group, especially aldehyde is very responsive to alkali, and be easy to oxidizedly, but acetal is equivalent to born of the same parents' diether, and is therefore more stable.Acetal can be hydrolyzed to original carbonyl compound, promptly when carbonyl in the molecule and the coexistence of other functional group, only wishes other functional group reactions, and does not wish that carbonyl is influenced, then carbonyl compound can be changed into acetal, after reaction is finished, again with its hydrolysis.Do not unite when the prerequisite that meets the demands in other indexs is issued to dissolving, disperse soon, dissolving is fast, has solved the bundle in the practical application approximately, has enlarged the field of using, and such as the application in paste putty, application in building glue, dispersity is 100%.Instant hydroxypropyl methyl cellulose ether of the present invention has been formulated industry standard Q/09FYT002-2008 according to the market requirement, according to company standard main physical and chemical index is detected, and detected result is seen attached list.

As can be seen from the above table, the main physical and chemical index of instant hydroxypropyl methyl cellulose ether of the present invention's preparation meets the requirements, and can meet the need of market.

In order further to prove the advantage of technology of the present invention, the instant hydroxypropyl methyl cellulose ether of prepared of the present invention and the hydroxypropyl methyl cellulose ether of traditional technology preparation are under equal conditions compared test, find that instant hydroxypropyl methyl cellulose ether of the present invention disperses at once at cold water, in a hour time, just can dissolve thickening, be committed to application; And traditional hydroxypropyl methyl cellulose ether occurs uniting at cold water, is difficult to disperse, and needs ability dissolving thickening in 3-5 hour under constantly stirring, and is committed to application.From the dissolution time of reality, just can significantly improve working efficiency.

Embodiment

Further specify technical scheme of the present invention below in conjunction with detailed process.

With the reaction solvent medium (toluene that comprises 87% part by weight, 13% Virahol) squeezes into reactor with pump, sodium hydroxide is dropped in the still, be warming up to 70 ℃, with alkali dissolution, be cooled to 25-30 ℃ then, drop into the purified cotton powder, under 25-30 ℃ condition, alkalized 2 hours, generate sodium cellulosate, after alkalization is finished, add the etherifying agent propylene oxide, methyl chloride, isothermal reaction is 30 minutes under 25-30 ℃ condition, its etherifying agent is stirred, be warming up to 54 ± 1 ℃ then, isothermal reaction 1 hour, be warming up to 80 ℃ then at once, isothermal reaction reaction in 2 hours finishes, be cooled to 50 ℃ and add in a certain amount of acetic acid and regulate between the pH value 5-7, then material is pressed into the recovery still, solvent exchange is reclaimed with the soft water more than 95 ℃, after having reclaimed, by whizzer material is separated with soft water, material enters does not have the axle spiral conveyer, and will be equipped with the linking agent oxalic dialdehyde this moment in 1: 8 ratio, by spray gun oxalic dialdehyde is sprayed material to the auger, every 660Kg Mierocrystalline cellulose purified cotton sprays into linking agent oxalic dialdehyde 100Kg, reaches crosslinked purpose by the stirring of not having the axle spiral, and material is again by not having the axle helical feed to flash dryer then, obtain final product after the drying, i.e. instant hydroxypropyl methyl cellulose ether.

Claims (2)

1. the preparation method of an instant hydroxypropyl methyl cellulose ether, it is with the sodium hydroxide generation sodium cellulosate that alkalizes with the Mierocrystalline cellulose purified cotton, use propylene oxide then, methyl chloride carries out etherification reaction and generates hydroxypropyl methyl cellulose ether, again by neutralization, reclaim solvent, washing and dry, it is characterized in that, material is after washing is centrifugal, do not entering in the exsiccant process by there being the axle auger, in having the axle auger, do not spray into the linking agent oxalic dialdehyde, require every 660Kg Mierocrystalline cellulose purified cotton to spray into linking agent oxalic dialdehyde 100Kg, make its abundant stirring reaction, enter flash dryer again, obtain dispersity and be 100% instant hydroxypropyl methyl cellulose ether;

Described linking agent oxalic dialdehyde is to be stirred according to 1: 8 mixed less than the soft water of 0.03g/L with hardness by 35% oxalic dialdehyde to form.

2. instant hydroxypropyl methyl cellulose ether that comes by the described preparation method of claim 1 preparation, it is by alkalization with the Mierocrystalline cellulose purified cotton, etherificate, neutralization, reclaim solvent, washing and dry, it is characterized in that, material is after washing is centrifugal, do not entering in the exsiccant process by there being the axle auger, in having the axle auger, do not spray into the linking agent oxalic dialdehyde, require every 660Kg Mierocrystalline cellulose purified cotton to spray into linking agent oxalic dialdehyde 100Kg, make its abundant stirring reaction, enter flash dryer again, obtain dispersity and be 100% instant hydroxypropyl methyl cellulose ether;

Described linking agent oxalic dialdehyde is to be stirred according to 1: 8 mixed less than the soft water of 0.03g/L with hardness by 35% oxalic dialdehyde to form.