Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1993-12-29
1996-03-05
Yoon, Tae H.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525247, 524556, 524560, 528480, 528485, 528488, C08F 842, C08F 600, C08J 302
Patent
active
054968917
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to carboxylic acid polymer compositions. More particularly it relates to concentrates of acrylic acid polymers and their use to prepare gels of diluted and neutralized polymer.
The polymers to which the invention relates include, in an aqueous state, cross-linked polymers of acrylic acid, which constitute a well known and established class of polymers. Polyacrylic acid cross-linked with (poly) vinyl sucrose or (poly) vinyl pentaerythritol (also known as "allyl sucrose" and "allyl pentaerythritol) has been sold since 1954 and is commonly referred to as "carbomer", which is the official CTFA designation for such polymer. Carbomers are commercially available under the trade marks Carbopol (B F Goodrich Company), Acrisint (Sigma Prodotti Chimici S.r.l., Bergamo, Italy) and Synthalen (Sigma Prodotti Chimici S.r.l.), for example.
Carbomers are supplied in the acid form and when neutralized by the end user form aqueous gels at low concentrations of around 0.5% w/v, for example. The acid form of the polymer is also very viscous, but not as viscous as the neutralized form. Carbomers are commonly used in industry because of their desirable rheological, thickening and stabilising properties accompanied by low toxicity. Carbomers are therefore widely accepted for use in liquid detergents, cosmetics, toiletries and pharmaceuticals.
The properties of carbomers are well documented. When neutralized, they form useful aqueous gels at low concentrations which are normally of around 0.5% w/v. At slightly higher concentrations of around 2.5% the viscosity of the pastes obtained with the acid polymer is so high that the pastes become unworkable. Different types of carbomer (e.g. of different molecular weight) are available and these differ in their variation of viscosity with concentration.
Carbomers are incompatible with electrolytes (i.e. ions) because multivalent metal ions, in particular, cause a serious reduction in viscosity of the neutralized polymer. For these reasons, users of carbomers take care to avoid unnecessary contamination with electrolytes, for example by dispersing them in deionised water. Likewise, plastics containers or resin-lined metal packages are preferred for products containing a carbomer, in order to reduce the risk of contamination with metal ions. In accepted convention therefore it is unthinkable that anybody would deliberately add multivalent cations to a dispersion of carbomer.
Although carbomers have become indispensable, they have a disadvantage which is so serious that users of carbomers are apt to state that they would not use carbomers if they did not have to. The problem is that carbomers are manufactured as finely divided powders of low density which are extraordinarily difficult to handle. The powder becomes electrostatic and when being transferred out of containers or mixed with water tends to be attracted to and to adhere to available surfaces and to dust into the air necessitating dust extraction equipment thus preventing build-up on the floor where it can become slippery and dangerous if wetted; this problem is compounded by the reluctance of the powder to be wetted and to disperse in water. All this means that preparation of aqueous dispersions is dusty, messy and time-consuming unless special and expensive equipment is used.
One solution to the handling problems would be for the manufacturer or supplier to mix the powder with water and to supply the customer with an aqueous dispersion of the polymer. However, because of the relatively high viscosities reached even at low concentrations of the order of 2 to 3% w/v in water, it is not practicable or economic to supply carbomers as aqueous concentrates: dispersions containing more than 2 or 3% polymer are normally unworkably viscous but more dilute dispersions contain so much water that they are not economic to transport.
Numerous attempts have been made to provide commercially acceptable concentrates but these attempts have all involved disadvantages, in that they require inclusion of raw materials, e.g
REFERENCES:
patent: 2798053 (1957-07-01), Brown
patent: 3915921 (1975-10-01), Schlatzer, Jr.
patent: 3940351 (1976-02-01), Schlatzer, Jr.
patent: 4062817 (1978-01-01), Spaulding
patent: 4066583 (1978-01-01), Spaulding
patent: 4690971 (1987-09-01), Flesher et al.
patent: 5171781 (1992-12-01), Farrar et al.
Brochure SIGMA Prodotti Chimici, "SYNTHALEN Thickening Agents for Cosmetic/Pharmaceutical Formulations".
Brochure B. F. Goodrich: "Carbopol-Water Soluble Resins".
Minister Peter E.
Stead Stanley G.
Surfachem Group PLC
Yoon Tae H.
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