Compositions: coating or plastic – Coating or plastic compositions – Heterocyclic
Reexamination Certificate
1998-12-07
2001-11-13
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Heterocyclic
C106S287170, C106S287240, C106S287300, C106S287320, C106S287340, C106S287350, C162S158000, C162S164100, C162S164600, C162S164700, C162S168200, C162S181800, C162S181600, C162S183000, C162S184000
Reexamination Certificate
active
06315824
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the emulsification and colloidal stabilization of emulsions and dispersions of hydrophobic in aqueous phases using a coacervate emulsifying or dispersing agent, and particularly to the coacervate emulsification or dispersion of non-rosin sizing agents. The invention is also directed to a stable sizing composition stabilized by the coacervate, a method of making the stable sizing composition, a method of using the sizing composition to produce sized paper, and sized paper, including paperboard, sized with the sizing composition.
Although the coacervate of the present invention may be useful for stabilizing various diverse types of emulsions and dispersions, including mineral oil in water, the invention will be described with reference to its preferred use as a stable emulsifying or dispersing agent for sizing agents for paper, and particularly, non-rosin sizing agents.
While there are a myriad of details for manufacturing paper, the paper manufacturing process conventionally comprises the following steps: (1) forming an aqueous suspension of cellulosic fibers, commonly known as pulp; (2) adding various processing and paper enhancing materials, such as strengthening and/or sizing materials; (3) sheeting and drying the fibers to form a desired cellulosic web; and (4) post-treating the web to provide various desired characteristics to the resulting paper, including surface application of sizing materials, and the like.
Sizing agents are typically in the form of aqueous solutions, dispersions, emulsions or suspensions which render the paper treated with the sizing agent, namely sized paper, resistant to the penetration or wetting by an aqueous liquid, including other treatment additives, printing inks, and the like. Sizing agents are internal additives employed during papermaking or external, surface additives employed at the size press that provide the enhanced characteristics.
Many different types of nonreactive and reactive sizing agents are well known in the papermaking industry. Paper typically made under acidic paper making conditions, referred to as acid paper, is usually sized with well-known rosin-derived sizing agents (referred to herein as “rosin sizing agents”), which are generally considered to be nonreactive sizing agents. Some papers made under neutral and alkaline paper making conditions may also be sized with rosin sizing agents. The above-identified related applications disclose coacervate dispersing agents for rosin sizing agents. The present invention is directed primarily to coacervate dispersing and emulsifying agents for non-rosin sizing agents typically used to make paper under alkaline paper making conditions, referred to as alkaline paper, as well as for general use in making stable dispersions and emulsions of other generally immiscible oil and aqueous phase compositions. The coacervate stabilizing agent of this invention is also usefull in stabilizing emulsions and dispersions of mixtures of sizing agents, including reactive and non-reactive, rosin and non-rosin sizing agents.
The most common sizing agents for fine alkaline paper, are alkenyl succinic anhydride (ASA) and alkyl ketene dimer (AKD). Another class of sizing agents useful for sizing fine paper includes ketene dimers and multimers that are liquid at room temperature, such as alkenyl ketene dimers and multimers. These are reactive sizing agents, since they have a reactive functional group that covalently bonds to cellulose fiber in the paper that causes their hydrophobic tails to be are oriented away from the fiber. The nature and orientation of these hydrophobic tails cause the fiber to repel water.
Certain properties of sizing agents are important to control for their efficient and economical use in making paper. One important property is sizing efficiency, i.e., the degree of sizing obtained per unit of sizing agent added. Sizing efficiency is determined by the amount and cost of materials used in making the sizing agent to obtain a desired sizing characteristic or group of characteristics. A more efficient sizing agent results in the desired characteristics at a lower amount or a greater efficiency, and thus, improved papermaking economies. Excess sizing agent can result in significant decreases in the paper quality by creating deposits on the papermaking machine, causing defects in the paper. Such deposits also reduce the production rate.
Sizing characteristics are affected by the type of sizing agent used, the type of paper to which the sizing agent is applied, and many other factors which have been the subject of a great deal of work in the past and a continuing body of work presently by those in the paper treatment industry. The present invention relates to sizing agent compositions in the form of emulsions or dispersions, cationic colloidal coacervate dispersion compositions for non-rosin sizing agents and mixtures of non-rosin and rosin sizing agents, as well as methods of making and using the resulting compositions and dispersions. The term “emulsion” (liquid in liquid) is sometimes used in the paper making industry to refer to what is technically a “dispersion” (solid in liquid).
Most sizing dispersions are made by a process involving forming an emulsion of a hydrophobic sizing agent in an aqueous medium at a temperature at which the sizing agent is in a liquid form. Upon cooling to ambient temperature the emulsion droplets solidify and a sizing dispersion results. The process needs an emulsifier and a stabilizer in order to process well. Upon application to the wet end of the paper making process, the particles of the sizing agent adsorb onto the cellulose fiber. Thermal drying causes the positioned sizing particles to melt and distribute along the fiber. The fiber then becomes less wetting, i.e. sized.
Polymers have been used in the past to help with the emulsification and also to promote interaction of the sizing particles with cellulose fiber suspensions. Starches and water soluble polymers such as polyamidoamines have been used in this context.
Various sizing compositions comprising sizing agents and dispersion aids have been previously disclosed.
International Application Publication No. WO 97/28311, published Aug. 7, 1997, corresponds to copending parent U.S. application Ser. No. 08/594,612 and now-abandoned grandparent U.S. application Ser. No. 09/046,019, of which the present application is a continuation-in-part, as noted above. The published International Application discloses a coacervate of the type used in the present invention used as an emulsifier system for rosin sizing agents. There is no disclosure of the use of the coacervate for emulsifying, dispersing or stabilizing other types of sizing agents or other hydrophobic/aqueous systems.
U.S. Pat. No. 4,240,935 (Dumas) discloses a paper sizing composition comprising a ketene dimer, an anionic dispersing agent such as sodium lignin sulfonate, certain water-soluble cationic resins and water. The cationic resins are composed of the reaction products of epichlorohydrin and an aminopolyamide derived from a dicarboxylic acid and a polyalkylene polyamine having two primary amino groups and at least one secondary or tertiary amine group. Another group of cationic resins is the reaction product of epichlorohydrin and the condensates of cyanamides or dicyandiamnide with a polyalkylene polyamine having a given formula including such compounds as polyethylene polyamines, polypropylene polyamines and polybutylene polyamines.
U.S. Pat. No. 4,263,182 (Aldrich) and U.S. Pat. No. 4,374,673 (Aldrich) both disclose aqueous paper sizing compositions in the form of dispersions consisting essentially of finely divided fortified rosin particles, a water-soluble or water-dispersible cationic starch dispersing agent for the rosin particles, an anionic surface-active agent and water. The distinguishing characteristics between the patents include the use of different types of starches. The '182 patent discloses using cationized starches which are anionic starches modified by reaction
Akin,Gump, Strauss, Hauer & Feld, L.L.P.
Brunsman David
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