DE2213756A1 - Aq copolymer dispersions - prepd from styrene, (meth) acrylate methylol (meth) acrylamide, (meth) acrylic acid - Google Patents

Abstract

Aq. copolymer dispersions, suitable for pigment-free coating of papers, e.g. hot-sealing-, decorative- and packaging papers, are prepd. by polymerising 45-60 wt.% styrene, 25-59 wt. % of an acrylate and/or methacrylate of an 8-12 C non-tert. alkanol, 0.5-5 wt. % N-methylolacryl-and/or methacrylamide and/or N-alkyoxymethylacryl- and/or -methacrylamide, 1-3 wt. % acrylic- and/or methacrylic acid, and opt. 10 wt. % further olefinically unsatd. monomers, in an aq. emulsion, using standard polymsn. catalysts, emulsifiers and temps. Papers treated are less sensitive to humid atmos., e.g. tropical conditions, than papers coated with dispersions of styrene copolymers contg. only lower alkyl acrylates or methacrylates, do not draw together or corrugate, and show an tendency to yellowing.

Description

Process for the preparation of aqueous copolymer dispersions For the preparation of aqueous dispersions of styrene copolymers by emulsion copolymerization A large number of processes are known of styrene. Come as comonomers especially lower alkyl esters of acrylic and / or methacrylic acid, such as ethyl acrylate and n-butyl acrylate or butadiene, and also in minor amounts c (B-olefinically unsaturated monocarboxylic acids and / or their amides are considered, if the aqueous dispersions are to be used for coating paper. In the known manufacturing processes, water-soluble peroxides, such as hydrogen peroxide, sodium, potassium and / or ammonium persulfate or so-called Redox catalysts, e.g. based on mixtures of peroxides of the type mentioned, and water-soluble, reducing substances, such as sodium hydrogen sulfite and Sodium formaldehyde sulfoxylate is used. The amounts of the catalysts mentioned Type are mostly in the range from 0.1 to 2 percent by weight, based on the Amount of monomers. The emulsifiers used are generally anionic or nonionic surface-active substances, such as sodium or potassium salts containing 15 to 20 carbon atoms, mostly saturated aliphatic carboxylic acids, fatty alcohol sulfates such as lauryl sulfate, and / or the alkylene oxide addition products, in particular ethylene oxide addition products of fatty acids, fatty alcohols or fatty acid amides with 10 to 25 alkylene oxide units used. The concentrations of such emulsifiers are in the known processes generally in the range from 1 to 5, in particular from 2 to 4 percent by weight, based on the monomers, selected, and the monomeric and aqueous phases are set generally in such proportions that 2 to 607, in particular 40 to 50 percent copolymer dispersions are obtained.

When using such copolymer dispersions for coating The dispersions are optionally made of raw paper with pigments, such as Chinaclay, titanium dioxide or chalk and possibly other additives, such as antifoams or pigment dispensers, and applied to paper or cardboard and the coated sheet-like structures are dried.

However, when they are used to coat paper, they show styrene copolymer dispersions prepared in a conventional manner at frequently very good adhesion and good rheological properties as well as good compatibility with additives of the type mentioned Disadvantages of the coated papers or

Cardboard boxes in a very humid atmosphere. These disadvantages are particularly evident under tropical conditions, for example due to a slope of the coated Paper to curl.

The object of the present invention is now a method for production of aqueous dispersions based on styrene copolymers, the said Do not have disadvantages.

It has now been found that aqueous copolymer dispersions can be used by emulsion copolymerization of styrene, an alkyl (meth) acrylate, a «, ß-olefinic unsaturated monocarboxylic acid and / or an amide of an o (, ß-olefinically unsaturated Monocarboxylic acid and, optionally, up to 10 percent by weight of others olefinically unsaturated monomers using the usual polymerization catalysts and produce emulsifiers at the usual polymerization temperatures with advantage can by adding 45 to 50 weight percent styrene, 25 to 59 weight percent one Acrylic and / or methacrylic acid ester of a non-tertiary containing 8 to 12 carbon atoms Alkanols, 0.5 to 5 percent by weight of N-methylolacryl and / or methacrylamide and / or N-alkoxymethylacrylamide and / or methacrylamide and 1 to 3 percent by weight Acrylic and / or methacrylic acid copolymerized in an aqueous emulsion.

Acrylic and / or methacrylic acid esters are those of primary, branched alkanols with 8 to 12, in particular with 8 carbon atoms of particular interest, the acrylic esters are generally preferred. examples of suitable acrylic and methacrylic acid esters are those of n-octanol-1, n-octanol-2, 2-ethylhexanol -1, n-decanol-1 and n-dodecanol-2. Contain suitable N-alkoxymethylamides of the type mentioned mostly straight-chain or branched alkyl groups containing 1 to 4 carbon atoms, in particular a methyl or n-butyl group.

In addition to in monomers of the type mentioned, in the case of the new Process up to 10 percent by weight of other olefinically unsaturated monomers, in particular 2 to 10 percent by weight of acrylonitrile and Z or 0.5 to 3 percent by weight bifunctional monomers such as ethylene glycol diacrylate, butanediol-1,4-diacrylate and methacrylate, vinyl acrylate and methacrylate or dicarboxylic acids, such as maleic, fumaric and itaconic acid and also divinylbenzene and dialkyl phthalate can be used. Such copolymer dispersions are of particular interest in their production 0.25 to 3 percent by weight, based on the total monomers, acrylic and / or Methacrylamide are polymerized.

The emulsion copolymerization of the monomers of the type mentioned can be carried out in a conventional manner, the amount of monomers mostly between 40 and 60 percent by weight, based on the total amount of monomers and aqueous phase. It can be the usual water-soluble, radical-forming Polymerization catalysts, such as particularly water-soluble peroxides and persulfates, such as hydrogen peroxide, sodium, potassium and ammonium persulfate, in the usual ones Quantities are used. The usual anionic and / or nonionic ones are also used Emulsifiers, such as those in the book by Rouben-Weyl "Methods of organic Chemistry ", Volume XIV / 1, Macromolecular StoMB, Georg Thieme-Verlag, Stuttgart 1961), Pages 192 to 208, are suitable in the usual amounts. Here can particularly finely divided copolymer dispersions are obtained if, for example, with relatively large amounts of emulsifier work and - which is preferred - none Adding protective colloids.

In the process, some of the monomers, especially the water-soluble Proportion of monomers in the aqueous phase that.

Polymerization catalysts and emulsifiers and optionally Contains buffer substances and / or regulators, presented, and the remaining Monomers according to the consumption of the polymerization vessel, optionally in emulsified form. In some cases it is also useful to use the to prepare entire monomers as an emulsion and then the approach in the usual way to polymerize. Finally, in some cases it can also be an advantage to polymerize continuously. In general, the new one polymerizes Process at temperatures of 20 to 1000C, preferably at temperatures of 60 up to 95 0C. The pH of the polymerization mixture is preferably below 5, especially between 1 and 4. After the end of the polymerization, if necessary unreacted monomers in the usual way, for example by passing through Water vapor or nitrogen.

The new process gives aqueous styrene copolymer dispersions, especially for pigment-free sealing of papers, e.g. for heat-sealing papers, Decoration papers and packaging papers are suitable. You surrender at this Use papers that are particularly less sensitive to a humid atmosphere. For example, papers coated in this way tend particularly in a humid atmosphere little to warp or become wavy. They outperform pigment-free coated ones Papers, for their production comparable dispersions of styrene copolymers are used, the only lower acrylic or methacrylic acid esters, such as Ethyl acrylate or n-butyl acrylate, polymerized included. Compared to coatings from dispersions of copolymers of the PVDC have coatings from the after The dispersions produced by the new process have the advantage that they do not yellow.

Refer to the parts and percentages given in the following examples focus on the weight.

Example 1 In a reactor equipped with an inert gas feed line, stirrer and Feed vessel is provided, a mixture of 700 parts of water, 30 parts of a Adduct of 1 mole of n-octylphenol and 23 moles of ethylene oxide and 9 parts of the sulfated and adduct of n-octylphenol and 23 parts of ethylene oxide neutralized with sodium hydroxide solution under Inert gas and heated to 870C with stirring. This template comes with a A solution of 0.5 part of potassium persulfate in 12 parts of water is added. At 87 ° C it becomes a primary emulsion of 660 parts of styrene, 520 parts of 2-ethylhexyl aaylate, 20 parts Acrylonitrile, 13 parts of acrylic acid, 10 parts of N-methylol methacrylamide, 1 part of diallyl phthalate, 5 parts of sodium dodecylbenzenesulsonate2 10 parts of the sodium salt of the adduct from n-octylphenol and 23 mol of ethylene oxide, 0.1 part of ammonium carbonate and 770 parts Water (= feed I) was introduced evenly into the polymerization reactor over three hours. At the same time, a solution of 4.5 parts of potassium persulfate in 110 parts of water is left run into the reactor (= feed II). The polymerization is two hours after the end of the feed at 870c up to 98.5% conversion has expired. After cooling the resulting finely divided The polymer dispersion is adjusted to pH 8 with ammonia. The polymer dispersion has a material content of 44 j. Proceed as indicated for example 1 under Use of a monomer mixture of 550 parts of styrene, 647 parts of 2-ethyhexyl acrylate, 16 doughs of methacrylic acid, 6.1 parts of acrylamide and 18.3 parts of N-methoxymethyl methacrylamide The resulting polymer dispersion is 43.7 percent and has an LT value of 82 ß (LD value = translucency value - it indicates what percentage of vertical penetration irradiated white light is transmitted. compared to the light transmission of pure water - moo or example 3 According to example t, a monomer mixture polymerized from 510 parts of styrene, 366 parts of 2-ethylhexyl methacrylate, 183 parts of n-octyl acrylic ester, 55 parts of N-methylol methacrylamide and 15.1 parts Methacrylic acid.

The resulting copolymer dispersion is 44.2 percent and has an LD value of 87%.

Example 4 From 560 parts of styrene, 540 parts of 2-ethylhexyl acrylate, 30 parts of acrylic acid, 70 parts of N-methylol methacrylamide, 1.2 parts of 1,4-butanediol monoacrylate, 15 parts of the disodium salt of Dodecyldiphenyläthyldisulfonats (Dow-Fax 2A1) and 365 Parts of water are used to produce a primary emulsion by vigorous stirring under an inert gas. This is simultaneously with 125 parts of a 4 percent potassium persulfate solution in 3 hours in a reactor vessel provided with a solution heated to 90 ° C 3 Telen Dow-Fax 2A1, 6 parts of an addition product of 1 mole of isononylphenol and 15 moles of ethylene oxide and 0.1 part of sodium bicarbonate in 730 parts of water. The conversion after a total polymerization time of 5 hours is 98.8%.

The cooled polymer emulsion is filtered off from traces of coagulate.

The dry content of the finely divided polymer dispersion with a LD value of 94 ao is 50.9%. The dispersion filmed at 2000 to a clear brilliant polymer film. At a shear rate of 420 (sec ) 2.7 poise.

Example 5 According to Example 4, a monomer mixture is used from 732 parts of styrene, 252 parts each of 2-ethylhexyl methacrylate and lauryl acrylate, 12.5 parts each of acrylic acid, methacrylamide and N-butoxymethyl methacrylamide and 3.15 Part of sodium 3-sulfopropyl methacrylate polymerized.

It is a sibile polymer dispersion of the LT value 89% with a Obtained solids fluff of 50.0%.

Example 6 700 parts are placed in a polymerization kettle with a stirrer Water, 5 parts of sodium sulfosuccinic acid dinonyl ester, 5 parts of addition product submitted from a 015 / Cl8 tallow fatty alcohol and 11 mol of ethylene oxide and the resulting Solution heated to 500c under inert gas. In feed vessels are used as feed I a Emulsion of 480 parts of styrene, 230 parts of acrylic acid lauryl acrylate, 21C parts of 2-ethylhexyl acrylate and 12 parts of acrylic acid, which neutralizes with ammonia up to pH 6.5 was, 20 parts of N * itoxymethylacrylamide, 5 parts of N-tynylpyrrolidone, 45 parts of acrylonitrile, 15 parts of sodium sulfosuccinic acid dinonyl ester, 10 parts of an adduct from 1 mole of n-octylphenol and 25 moles of ethylene oxide and 415 parts of water1 as feed II 200 parts of a 3 percent aqueous potassium persulfate solution and, as feed III, 200 Parts of a 2 percent aqueous sodium pyrosulfite solution provided. The polymerization is achieved by specifying 10 percent by volume of feed III, 5 percent by volume of feed II and 12 percent by volume of feed I introduced to the receiver heated to 50 ° C. the Feeds I and III and 70 percent by volume of feed II are so in 1.5 hours retracted the polymerization reactor that the temperature of the reaction mixture set to 65 to 700C.

After the remainder of feed II has been added, the mixture is at 80 ° C. for 2 hours polymerized.

The resulting, finely divided dispersion of 39.7% solids content is After cooling and neutralization with ammonia, 10 parts of moist coagulate are filtered off. The dispersion forms a transparent, shiny and smooth when it dries Polymer film. The K value of the polymer (determined according to H. Fikentscher, CI1ulosechemie 1D, page 58, 1932, in dimethylformamide) is 74.

The copolymer dispersions obtained according to Examples 1 to 6 are ideal for coating paper; papers coated therewith are particularly less prone to waviness in a humid atmosphere and hitting us in it Papers coated with dispersions not produced according to the invention became.

Claims (2)

Claims 19. Process for the preparation of aqueous copolymer dispersions by emulsion copolymerization of styrene, an alkyl (meth) acrylate, a d, B-olefinic unsaturated monocarboxylic acid and / or an amide of a «, B-olefinically unsaturated Monocarboxylic acid and, optionally, up to 10 percent by weight of others olefinically unsaturated monomers using the usual polymerization catalysts and emulsifiers at the usual polymerization temperatures, characterized in that that one has 45 to 60 percent by weight of styrene, 25 to 59 percent by weight of an acrylic and / or Methacrylic acid ester of a non-tertiary alkanol containing 81is 12 carbon atoms, 0.5 US 5 percent by weight of N-methylolacryl and / or methacrylamide and / or N-alkoxymethyl acryl and / or methacrylamide, 1 to 3 percent by weight acrylic and / or methacrylic acid polymerized in aqueous emulsion. 2. Use of the aqueous copolymer dispersions produced according to claim 1 for pigment-free paper coating.