Method for the preparation of modified cellulose ethers

Abstract

The invention relates to the preparation of a cellulose ether that is hydrophobically modified with an alkyl or alkenylketene dimer the general formula of which is in which R1 and R2 are alkyl or alkenyl chain, such as one having 5 to 22, preferably 13 to 20, most preferably 14 to 18 carbons. The product can be used in water-based products to control the rheological properties, for example. Objects of use include, for example, detergents, paper coating mixtures, paints, dispersing agents, and oil drilling muds.

Description

[0001] The invention relates to the preparation of hydrophobically modified cellulose ethers.[0002] Cellulose ethers, such as carboxymethyl cellulose, are employed in a wide variety of applications to treat the rheological properties of aqueous solutions in particular. Objects of use include, for example, foods, medicines, cosmetic preparations, detergents, agricultural chemicals, textiles, printing inks, paper coating agents, construction materials, adhesives, paints, ceramic materials, and additives of polymerisation.[0003] Cellulose ethers can be modified by attaching different substituents to hydroxyl groups in cellulose. In this way, the solubility or the hydrophobicity of cellulose ether in particular can be affected.[0004] There is a lot of literature concerning the hydrophobic modification of polysaccharides.[0005] U.S. Pat. No. 4,228,277 describes the modification of non-ionic cellulose ethers, such as methyl cellulose, methyl hydroxypropyl cellulose, hydroxypropyl cellulos...

AI Technical Summary

Benefits of technology

[0011] Cellulose ether modified with alkylketene dimer is easy to manufacture. The process is safe, simple, and quick. The modification can also improve the dispersability of cellulose ether in water.

[0016] Elevated reaction temperatures are preferable, such as 30-120.degree. C., preferably 50-90.degree. C., and most preferably 60-85.degree. C., so that at elevated temperatures AKD is melted first. High temperature and alkaline pH improve the reactivity of AKD with cellulose lose ether. AKD can react with substituents, for example carboxymethyl groups in cellulose ether. AKD can also react with other compounds which contain an OH group. These include water, alcohol, and sodium glycolate which are generated in the preparation of CMC. The thus generated compounds also have an effect on the hydrophobicity of the product.

[0026] Cellulose ether can be modified with AKD by various methods. AKD can be added to the cellulose ether at any stage of the production, for example, in mercerisation, etherification, or drying. AKD can be added in a solid form or as a dispersion. High temperature and alkaline pH improve the reactivity of AKD with cellulose ether.

[0028] The manufacture of the hydrophobically modified cellulose ether according to the invention is simple and quick. Neither complex solvents nor long reaction times are needed. In addition, AKD is a safe chemical. It is neither combustible nor explosive; therefore, it neither causes a danger in a process nor is it dangerous to the environment. AKD is not hazardous or irritating and it does not cause allergies; therefore, it does not present any danger to the process personnel or the end-user.

Problems solved by technology

However, it is uncomfortable to use epoxy compounds because they are detrimental to health.

The alkyl reagent can be halide, halohydride, or epoxide, all of which are hazardous to environment and health.

This manufacturing process also has a long reaction time, 6 or up to 12 hours.

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