Paper size mixtures

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...

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524827, 524832, 106210, 106213, 1062872, 62158, C08L 300, C08L 8900, C09D 400

Patent

active

054986486

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to paper size mixtures comprising C.sub.14 -C.sub.22 -alkyldiketene emulsions and finely divided, aqueous polymer dispersions having a sizing effect, and to the use of the paper size mixtures as engine and surface sizes for paper.
U.S. Pat. No. 3,130,118 discloses that alkyldiketenes having at least 6 carbon atoms in the molecule can be emulsified in water in the presence of cationic starch. The resulting alkyldiketene emulsions having a relatively low concentration are used as engine sizes for paper. Papers engine sized with these emulsions develop the full sizing effect not directly after the paper drying process but only after the paper has been stored for one or more days at room temperature. However, sizes which develop the full sizing effect immediately after drying of the sized paper are required in practice.
DE-A-3 000 502 discloses that aqueous emulsions of fatty alkyldiketenes mixed with cationic condensates can be used as sizes. Examples of suitable cationic condensates are epichlorohydrin-crosslinked reaction products of condensate of dicyanodiamide or cyanamide and a bisaminopropylpiperazine or condensates of epichlorohydrin and bisaminopropylpiperazine. The cationic condensates result in accelerated development of the sizing effect of fatty alkyldiketenes but possess the disadvantage that they have an adverse effect on the whiteness of the paper.
DE-A-3 316 179 discloses that emulsions of fatty alkyldiketenes together with polyethyleneimines and/or water-soluble condensates based on water-soluble polyamidoamines grafted with ethyleneimine and then crosslinked with epichlorohydrin can be used as sizes for paper. Even when these size mixtures are used, the diketene sizing effect develops within a short time. However, the cationic size accelerators for fatty alkyldiketenes are very sensitive to interfering substances which accumulate during the papermaking process in the paper mills, owing to the partially or completely closed water circulation. They also have an adverse effect on the whiteness of the paper.
EP-A-0 437 764 discloses stabilized aqueous alkyldiketene emulsions which may contain up to 40% by weight of an alkyldiketene in an emulsified form and which contain long-chain fatty esters and/or urethanes as stabilizers.
JP-A-58/115 196 discloses a paper assistant which increases the strength of paper and at the same time sizes the paper. This paper assistant is based on a dispersion of a graft copolymer of styrene with alkyl acrylates on starch. The graft copolymers are obtained by polymerizing styrene and an acrylate in an aqueous medium at from 20.degree. to 100.degree. C. with formation of an aqueous dispersion.
EP-B-0 257 412 and EP-B-0 267 770 disclose paper sizes based on finely divided, aqueous dispersions of copolymers which are obtainable by copolymerizing C.sub.3 -C.sub.8 -alcohol and copolymerizable monomers a degraded starch, in the presence of initiators containing peroxide groups. The degraded starches have viscosities .eta..sub.i of 0.04-0.50 dl/g.
EP-B-0 051 144 discloses finely divided, aqueous polymer dispersions which are a paper size and are prepared by a 2-stage polymerization. In the first stage of polymerization, a low molecular weight prepolymer of a nitrogen-containing monomer, a nonionic, hydrophobic ethylenically unsaturated monomer and an ethylenically unsaturated carboxylic acid or maleic anhydride is first prepared. This prepolymer serves as a protective colloid for the subsequent second stage of polymerization, in which nonionic hydrophobic ethylenically unsaturated monomers are polymerized by an emulsion polymerization method in the presence of conventional amounts of water-soluble polymerization initiators.
EP-A-0 058 313 and EP-A-0 150 003 disclose cationic paper sizes which are obtained by copolymerizing acrylonitrile and acrylates and/or methacrylates or monomer mixtures of styrene, acrylates and/or methacrylates and, if required, acrylonitrile and/or methacrylonitrile in an aqueous solution of a cationic copolymer as an em

REFERENCES:
patent: 484429 (1892-10-01), Holland
patent: 3006806 (1961-10-01), Schlir
patent: 3130118 (1964-04-01), Chapman
patent: 4243481 (1981-01-01), Dumas
patent: 4317756 (1982-03-01), Dumas
patent: 4434269 (1984-02-01), Probst et al.
patent: 4659437 (1987-04-01), Probst
patent: 4855343 (1989-08-01), Degen et al.
patent: 5154763 (1992-10-01), Ksoll et al.
Japanese Laid-Open Application No. J58/115,196, Dec. 26, 1981.

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