Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1983-12-22
1986-07-22
Lieberman, Allan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
428511, 428514, 523334, 524501, 524522, 524523, 524524, 525218, 525221, B32B 2308, B32B 2710, C08L 2510, C08L 3302
Patent
active
046020594
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a synthetic polymer composition useful as the binder component in coating colors and to the coating colors containing these polymeric compositions.
In the production of paper, the paper surface is often coated with a composition (commonly referred to as a coating color) which imparts desirable properties such as printability to the paper. In one conventional method for applying the coating color, the coating is continuously transferred as a liquid film from an applicator roll to the paper surface, with any applied excess removed using suitable means such as blade or air-knife techniques.
For various reasons, paper producers have continuously strived to reduce the finished weight of the coated paper. One method by which this can be achieved is by reducing the amount of the coating color applied to the paper. Unfortunately, a reduction in the coat weight generally results in a drop of the finished paper properties, particularly in the print quality. To effectively coat the paper, at the desirably coat weight, the coating colors advantageously exhibit desirable physical properties, e.g., stability, and rheological properties. These properties are particularly important in the preparation of high quality paper grades such as those printed by gravure techniques.
Conventionally, the coating color consists primarily of a suspension of a pigment and/or filler such as clay in an aqueous medium containing a binder. Heretofore, natural high molecular weight materials such as starch or protein have been used as a binder. Unfortunately, these natural materials are susceptible to attack by microorganisms and when employed alone give brittle coatings. Moreover, using a starch binder, the coated paper often does not possess the required print quality due to insufficient coat hold-out, i.e., excessive penetration of the coatings into the paper.
It has therefore been suggested to employ synthetic polymers as the binder in paper coatings. Many such synthetic polymer binders consist of two polymeric components with one copolymer being employed primarily to impart the desired binding strength and other properties to the coated paper and the second copolymer component being employed primarily to affect the rheological properties of the coating colors prepared therefrom. For example, German Pat. No. 1,546,315 discloses a synthetic polymer binder comprising 60-95 percent of a first copolymer of butadiene, styrene and/or acrylonitrile and 5-40 percent of a second copolymer of acrylic or methacrylic acid, a monomer which forms a water-insoluble homopolymer (at least a portion of which is an ester of acrylic or methacrylic acid) and, optionally acryl- or methacrylamide. Unfortunately, the properties of paper coated with coating colors prepared from this binder are generally deficient, particularly using gravure printing techniques, due again to insufficient coat hold-out.
A similar synthetic polymeric binder except that the first copolymer is derived from an ester of acrylic or methacrylic acid, a vinyl ester or propionic acid, and optionally other copolymerizable monomers, is described by U.S. Pat. No. 3,365,410. While coating colors prepared using these polymeric binders improve the print quality of paper prepared therefrom, a further improvement in the balance of the paper properties is required.
In view of the aforementioned deficiencies of the synthetic polymer binders employed heretofore, it remains highly desirable to provide a polymeric composition which can effectively be employed as the binder in a paper coating color to impart an improved balance of properties in the paper coated therewith.
Accordingly, the present invention is such an improved polymeric composition useful as the binder component in a coating color. The polymeric composition is composed of two polymeric components, the improvement in said composition comprising the inclusion, as one of the two polymeric components, of a lightly crosslinked copolymer comprising, in polymerized form, an ester of an .alpha.,.beta.-ethylenical
REFERENCES:
patent: 3365410 (1968-01-01), Wesslau et al.
patent: 3903035 (1975-09-01), Affeldt et al.
patent: 4157995 (1979-06-01), Schenck et al.
patent: 4309321 (1982-01-01), Alhara et al.
patent: 4321181 (1982-03-01), Barabas et al.
Martinez Jose L. T.
van Rooden Bernardus J. M. S.
Lieberman Allan M.
The Dow Chemical Company
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