Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1989-06-30
1993-01-12
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
524 5, 524 6, 524 69, 528150, 525161, C08F26704, C08K 300
Patent
active
051791706
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel dispersant, in particular, to a dispersant having improved dispersing ability and aging stability that is composed of a water-soluble salt either of a copolymer of a component in naphtha oil having a reactive double bond and maleic anhydride or a partial esterification product of said copolymer. The dispersant of the present invention may be applied to every field where inorganic or organic fine powders are used in dispersion systems and it finds utility in a broad range of applications including paints, inks, paper processing, pigment manufacture, civil engineering, mud stabilizers, ceramics, ferrites, fuels, etc.
The present invention also relates to an admixture for cements which harden by the action of water. More particularity, the present invention relates to a cement admixture that not only fluidizes cement mixes such as cement pastes, mortars and concretes but also ensures that their flowability will not decrease greatly with time.
BACKGROUND ART
Dispersants are commonly added in small amounts to ensure that inorganic or organic fine powders are uniformly dispersed in water or solvents so that the resulting dispersions have low viscosity and high flowability. Improved dispersibility will contribute not only to an improvement in the quality of the final product or its workability or handling property but also to an improvement in economy through the increase in the concentration of dispersions. Hence, dispersibility is a very important factor in various fields, to say nothing of the importance of the performance of the dispersants to be employed.
Sodium hexametaphosphate has been used for many years as a dispersant for pigments to be incorporated in coated paper. Sodium polyacrylate is known as an effective dispersant in a broad range of fields. Copolymers such as those of .alpha.-olefins and maleic anhydride and those of styrene and maleic anhydride have also been used as dispersants for pigments after they are converted to water-soluble salts.
However, none of the dispersants available today are completely satisfactory in terms of dispersing ability and aging stability.
In order for cement mixes (e.g. cement pastes, mortars and concretes) to have improved workability, they must exhibit high initial flowability and experience small change in flowability with time. The flowability of cement mixes is known to decrease with time due primarily to hydration reaction of cement with water and to physical aggregation of cement particles. Upon mixing the ingredients, hydration reaction of cement with water occurs in cement mixes and as time lapses, physical and chemical aggregation of cement particles proceeds to reduce cement flowability and its workability and constructibility will consequently decrease with time. This phenomenon is commonly referred to as "flow reduction" in mortars or "slump loss" in concretes and limits the "open time" of cement mixes. In the case of fresh concretes, slump loss causes various problems such as limited time of transportation, prolonged standby on the installation site and temporary interruptions of transfer by pumping, all these phenomena leading to undesirable effects such as deterioration of quality and low operational efficiency. Slump loss is also deleterious to fabricated concrete products since it limits molding time or causes insufficient centrifugal re-compaction. Therefore, slump loss, or time-dependent decrease in the flowability of cement mixes such as cement pastes, mortars and concretes, is a critical problem to be solved.
Several proposals have so far been made with a view to preventing slump loss in concretes. Japanese Patent Publication No. 51-15856 shows a method in which a concrete admixture selected either from water-soluble salts of sulfonated aromatic compounds or from water-soluble salts of the products of condensation between sulfonated aromatic compounds and formaldehyde is added repeatedly to concrete to maintain its flowability for a prolonged period. This method is effective to some e
REFERENCES:
patent: 4079040 (1978-03-01), Ribka et al.
patent: 4431760 (1984-02-01), Giddings et al.
Enomoto Norihide
Naruse Yoshihiro
Ohtsu Kimiyo
Sugiura Keiji
Takagi Masato
Kawasaki Steel Corporation
Michl Paul R.
Yoon Tae H.
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