Dispersant and foaming agent combination
Pairs a naphthalene-sulfonate–formaldehyde dispersant with a defined molecular-weight window (MW 17 000 – 47 000) with an alkyl / alkyl-ether sulfate soap, so that air is entrained more efficiently and board weight drops without losing strength.
- Assignee
- Geo Specialty Chemicals Inc
- Inventors
- Arpad Savoly, Dawn P. Elko, Bennie Veal, James McCrary
- Jurisdiction
- United States (USPTO)
- Filed
- 2002-08-07
- Published
- 2004-08-10
- Priority
- 2002-08-07
Dispersants and foaming agents are usually developed separately: the chemistry team picks a dispersant for water reduction, and process picks a foamer for entrained air. This patent argues that the two are actually coupled — the MW distribution of the NS-formaldehyde polymer changes how the soap behaves at the air-water interface.
- 01The dispersant is a naphthalene-sulfonate–formaldehyde alkali-salt polymer restricted to a weight-average molecular weight of 17 000 to 47 000 g/mol.
- 02The foaming agent is a soap combining an alkyl sulfate and an alkyl-ether sulfate (both alkali salts).
- 03Together, according to the patent, the pair entrains air more efficiently — meaning more void volume for the same soap dose — which lowers total board weight without a matching loss of core strength.
| Parameter | Value | Source |
|---|---|---|
| Dispersant type | naphthalene-sulfonate–formaldehyde alkali-salt polymer | claim 1 |
| Dispersant weight-average MW window | ≈ 17 000 – 47 000 g/mol | claim 1 |
| Foaming agent | mixture of alkyl sulfate + alkyl-ether sulfate (alkali salts) | claim 1 |
- 01When qualifying a new dispersant lot, MW distribution — not only sulphonate content or solids — should be part of incoming-goods testing.
- 02A change of soap supplier can invalidate a stable dispersant/foam pair even when the new soap looks identical on paper. This patent is a good reference when troubleshooting sudden density drift after a supplier change.
The present invention provides a dispersant and foaming agent combination that is useful in the production of gypsum wallboard and other aqueous cementitious products. The dispersant in the combination according to the invention is a naphthalene sulfonate-aldehyde condensate alkali salt polymer having a weight average molecular weight of from about 17,000 to about 47,000. The alkali is preferably an alkali metal and/or an alkaline earth metal. The aldehyde is preferably formaldehyde. The foaming agent used in the combination according to the invention is a soap, preferably an alkali salt of an alkyl ether sulfate and/or an alkyl sulfate. The combination of a high molecular weight dispersant and a foaming agent produces a gypsum wallboard core effect that more efficiently entrains air (i.e., creates void space), thereby lowering overall board weight without detrimentally affecting strength.
A dispersant and foaming agent combination for use in the production of gypsum wallboard comprising: a naphthalene sulfonate-aldehyde condensate alkali salt polymer having a weight average molecular weight from about 17,000 to about 47,000; and a soap; wherein the aldehyde in the naphthalene sulfonate-aldehyde condensate alkali salt polymer is formaldehyde and the soap comprises a mixture of an alkyl sulfate and an alkyl ether sulfate.
Further claims, drawings, prosecution history and legal status: see the official record.
- [1]US 6,774,146 B2 — Dispersant and foaming agent combination — Google Patents · 2004-08-10