Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
  • D21H17/45—Nitrogen-containing groups

Definitions

• the invention relates to the use of aqueous cationic plastic dispersions in combination with polymeric retention aids for the mass sizing of raw paper pulps at neutral pH.
• an important process step in the production of paper is the sizing of the cellulose fibers in the production of base paper. It is used in the pre-production of paper from the cellulose raw material, among other things. the purpose of making the paper more writable and / or printable by appropriately hydrophobizing the cellulose fibers.
• Resin glues based on rosin which e.g. are precipitated from the aqueous phase of the cellulose pulp (paper pulp) by means of aluminum salts, whereupon they are drawn onto the cellulose fibers.
• the cellulose fibers hydrophobicized when the resin glue precipitates can easily be removed from the aqueous phase and obtained in the form of base paper webs.
• Cationic polymer solutions or polymer dispersions have therefore already been used for the production of sized paper at a neutral pH value, since the product-specific substantivity of polymeric cationic molecules means that they can be voluntarily applied to the cellulose fibers without destabilizing their solution or dispersion beforehand.
• DE-AS 1 053 783 discloses cationic copolymers which can be obtained by radical-initiated polymerization in bulk or in solution or in aqueous dispersion. They contain monomer units from esters or amides of acrylic or methacrylic acid which have at least one quaternary ammonium compound in the side-chain ester or amide radical of the monomer units, which is bonded to the hetero atom of the ester or amide group via an alkylene group.
• copolymers can also contain, as comonomer constituents, monomer units from the group of vinyl acetate, vinyl formate, vinylidene chloride, styrene, isobutylene, butadiene and butyl acrylate and are used for the production of molding compositions, films, fibers, adhesives, Lacquers, textile auxiliaries etc. used. It has been shown, however, that practically all of the cationic copolymer dispersions mentioned in DE-AS 1 053 783 are unsuitable for use as paper sizing agents, and that size paper produced therewith has unsatisfactory properties.
• cationic copolymer dispersions which can be used for the production of sized papers.
• the copolymers of these products contain 20 to 60% by weight of styrene and / or acrylonitrile, 20 to 60% by weight of (meth) acrylic acid ester and 5 to 50% by weight of cationic monomer units composed of ethylenically unsaturated compounds and quaternary nitrogen atom.
• these copolymers require those with a content of at least 20% by weight of cationic monomer units, which, given the limited availability and the high cost of the required cationic starting monomers, prevent their copolymers from being widely used.
• cationic copolymer latices which are said to be suitable as paper sizes.
• the copolymers of these products consist predominantly of vinyl esters, (meth) acrylic acid esters, vinyl aromatics and 1 to 20% by weight of partially nitrogen-containing monomer units which are capable of accepting cationic charges, preferably based on (meth) acrylamides, some of which are quaternized. They also contain nonionic or cationic emulsifiers. With regard to the possible use of these products in papermaking, however, no test results have so far become known.
• the present invention was therefore based on the object of making available a paper sizing agent for the mass sizing of paper at a neutral pH value which, in particular, enables inexpensive sizing, is easy to use and can lead to full sizing even at low application rates.
• the user should make simple and minor changes, e.g. Concentration variations also allow paper with low sizing levels to be obtained and, at the same time, the dry strength of the raw sized paper can be varied sufficiently.
• the invention therefore relates to the use of aqueous cationic plastic dispersions as neutral sizing agents for the mass sizing of raw paper pulps in a conventional aqueous suspension at neutral pH for the production of acid-free raw paper, characterized in that that aqueous cationic copolymer dispersions with a minimum cation activity of 20 ⁇ mol / g solid (FS), the cationic charge being more than half on the surface of the dispersion copolymer particles, the minimum film formation temperature (MFT) of the dispersion being below 50 ° C. the glass transition temperature T G of the copolymer is below 70 ° C. and above 0 ° C.
• aqueous cationic copolymer dispersions with a minimum cation activity of 20 ⁇ mol / g solid (FS), the cationic charge being more than half on the surface of the dispersion copolymer particles, the minimum film formation temperature (MFT) of the dispersion being below 50 ° C.
• the weight ratio of the polymeric retention aid to the cationic dispersion copolymer preferably 0.3: 1 to 0.005: 1, at a pH in the range from 6.5 to 7.5 in an amount of up to 2% by weight of cationic dispersion copolymer, based on the dry weight of the raw cellulose fibers, with the raw cellulose fiber suspension mixed intensively with the proviso that ß either the polymeric retention aid is added first and the cationic plastic dispersion is metered in, or the two agents are metered in separately at the same time to the aqueous cellulose fiber suspension with intensive mixing, if appropriate with the addition of inert fillers, pigments, dyes and customary auxiliaries, including fillers Calcium carbonate base, and then the acid-free raw paper is isolated and dried from the aqueous suspension in a conventional manner, preferably in the form of raw paper webs or sheets
• the invention further relates to a process for the production of sized acid-free raw paper from raw cellulose fibers in a conventional aqueous suspension using aqueous cationic plastic dispersions and polymeric retention aids as neutral sizing agents at pH values from 6.5 to 7.5, characterized in that the Sizing agents, as specified in the previous paragraph, preferably at normal temperature, with the aqueous cellulose fiber suspension intensively mixed, optionally with the use of inert fillers, pigments, dyes and customary auxiliaries, including fillers based on calcium carbonate, and the sized, acid-free raw paper isolated and dried in the usual manner.
• Another object of the invention is acid-free, bulk-sized base paper in the form of flat sheets, sheets or moldings or in the form of flakes or nonwovens, produced by the above-mentioned process, optionally with the use of inert fillers, dyes and conventional auxiliaries, optionally from Calcium carbonate based fillers.
• polymeric retention aids As polymeric retention aids, the products known as polymeric retention aids and drainage accelerators are used in the usual application amounts, optionally in the form of their aqueous solutions or aqueous dilutions. These are either added as such simultaneously with the aqueous cationic copolymer dispersions used according to the invention to the aqueous cellulose fiber suspension in the neutral pH range, or the retention aid is pre-metered and the cationic copolymer dispersion is then added, the latter variant being preferred.
• Retention agents and dewatering accelerators are known to serve the purpose of increasing the fiber, fine and filler retention on the paper machine screen in conventional use. Furthermore, certain types of products can cause an increase in the dewatering speed on the wire and in the wet presses and a faster drying of the paper web in the dryer section, which can be used to increase production or save energy.
• the effect of the higher to high molecular weight products is based on a reduction in the negative zeta potential of the paper stock suspension and / or on the bridging of paper stock particles by the polymers, which in both cases causes the paper stock suspension to micro-flocculate.
• an effective paper sizing effect cannot be achieved by using the polymeric retention aids alone. It was therefore all the more surprising that the obviously synergistic increase in activity in paper sizing with cationic plastic dispersions by the combined use of polymeric retention aids and cationic copolymer dispersions according to the invention.
• Possible polymeric retention aids to be used according to the invention are in particular: Polyamines, preferably higher molecular weight polyalkylene polyamines, in particular polyethyleneimine, or reaction products such as can be obtained by crosslinking oligoamines with dichloroethane, epichlorohydrin or reaction products from epichlorohydrin and polyetherdiols, Polyamidoamines, preferably polyamidoamines, as can be obtained by reacting adipic acid with diethylenetriamine or similar polyamines and crosslinking with the abovementioned crosslinking agents, or reaction products based on ethyleneimine / adipic acid / polyamine / epichlorohydrin, Polyacrylamides, preferably high molecular weight polyacrylamides, such as anionically modified acrylamide / acrylic acid copolymers, cationically modified copolymers of acrylamide with aminoacrylic and methacrylic acid esters with tertiary and quaternary amine functions, cati
• 0.05 to 0.2% by weight, in particular 0.05 to 0.1% by weight, based on the dry cellulose weight, of retention aids in combination with a cationic copolymer dispersion of the cellulose fiber suspension are added with the proviso that either Retention aid as such is added simultaneously with the cationic copolymer dispersion, or that the retention aid is pre-metered and the cationic copolymer dispersion is then added.
• polymeric retention aids used in accordance with the invention can generally form colloidal aqueous solutions, they can advantageously be added to the cellulose fiber suspension in the form of colloidal aqueous solutions.
• all aqueous, cationically charged plastic or polymer dispersions are suitable as aqueous cationic plastic dispersions to be used according to the invention for raw paper sizing in the neutral pH range, preferably at pH values from 6.5 to 7.5, but preferably those with a medium dispersion Particle diameter of 0.05 to 0.5 ⁇ m and a minimum cation activity of 20 to 200 ⁇ mol / g solid (FS), where more than half of the cationic charge is on the surface of the dispersion copolymer particles, especially those whose cationic charge is too 60 to 90% is located on the surface of the dispersion copolymer particles.
• FS minimum cation activity
• the molecular weight of the dispersion copolymers is not critical and can preferably be from 10,000 to several million. Lower and higher molecular weights are also possible. In general, they are adapted to the requirements and objectives.
• the amount of cationic plastic dispersions used in combination with the above-mentioned retention aids is preferably 0.1 to 2% by weight, in particular 0.5 to 1% by weight, of dispersion copolymer solid (FS), based on the dry weight of the cellulose fiber mass used for sizing in the cellulose fiber suspension or raw paper pulp.
• Retention aids and aqueous cationic plastic dispersion, based on the copolymeric solids content (FS) of the cationic dispersion are particularly preferably used in a weight ratio of 0.2: 1 to 0.01: 1.
• Cationic dispersion copolymers which contain styrene / butyl acrylate, trialkylammonium alkyl (meth) acrylate chloride and N-methylol (meth) acrylamide as monomer units are particularly preferred.
• Suitable emulsifiers which are used in the preparation of the aqueous cationic copolymer dispersions to be used according to the invention, preferably in the emulsion polymerization of the comonomers, are conventional nonionic emulsifiers, in particular nonionic surfactants, preferably from the group of the reaction products of aliphatic, cycloaliphatic, araliphatic, aliphatic, aliphatic aromatic carboxylic acids, alcohols, phenols, amines with epoxides, such as Ethylene oxide, as well as block copolymers from various epoxides, e.g. Ethylene oxide and propylene oxide.
• nonionic surfactants preferably from the group of the reaction products of aliphatic, cycloaliphatic, araliphatic, aliphatic, aliphatic aromatic carboxylic acids, alcohols, phenols, amines with epoxides, such as Ethy
• Preferred emulsifiers are furthermore, for example, primary, secondary and tertiary fatty amines in combination with organic or inorganic acids and also tensioactive quaternary alkylammonium compounds.
• Amphoteric surfactants with a zwitterionic structure for example of the betaine type such as alkylamidopropylbetaines, are also suitable.
• Especially preferred emulsifiers are nonionic surfactants, in particular alkyl and alkylaryl polyglycol ethers with 15 to 50 ethylene oxide units. The emulsifiers mentioned can be used either individually or in combination with one another or with one another.
• the amount of emulsifiers to be used depends on the desired dispersion properties and is preferably 0.1 to 10% by weight, in particular 0.2 to 6, particularly preferably 0.3 to 4% by weight, based on the total amount of all monomer units in the copolymer.
• Suitable protective colloids are preferably those based on high molecular weight organic compounds which have hydroxyl, amino or ammonium groups and are water-soluble or water-dispersible, with essentially no or no pronounced interfacial activity and a pronounced dispersibility.
• Preferred protective colloids are, for example, cationic polyelectrolytes, for example poly-diallyldimethylammonium chloride (poly-DADMAC), cellulose ethers, polyvinyl alcohols, polysaccharides, (chitosan, starch), polyvinylpyrrolidones, it being possible for these compounds to be preferably substituted by amino groups or quaternary ammonium groups.
• the latter groups can be introduced into the underlying macromolecules, for example by substitution using cationizing reagents, such as, for example, glycidyltrimethylammonium chloride.
• Cationic polyvinyl alcohols can also be obtained, for example, by saponification of corresponding vinyl acetate copolymers containing amino and / or ammonium groups.
• Particularly preferred protective colloids are cationically modified polysaccharides and cationic polyelectrolytes.
• the amounts of protective colloid to be used depend on the desired dispersion properties, in particular the fine particle size of the dispersion particles. To be favoured Protective colloid amounts of between 0 and 5% by weight, in particular between 0.1 and 2% by weight, based on the total amount of monomers, are optionally used in the emulsion polymerization.
• the cationic plastic dispersions used according to the invention can be prepared by conventional emulsion polymerization using the feed or pre-emulsion process, preferably at 20 to 100 ° C., in particular at 50 to 90 ° C. Part of the monomer mixture can be prepolymerized in the aqueous liquor in a customary manner and the rest of the monomer mixture can be metered in continuously while maintaining the reaction at the reaction temperature.
• the cationic plastic dispersions used according to the invention have a high cation activity of preferably at least 20 to 200 ⁇ mol / g solid (FS), measured at pH 7, it being particularly advantageous if more than half, in particular 60 to 90%, of the cationic charges are themselves located on the surface of the copolymer particles.
• FS ⁇ mol / g solid
• a high content of cationic surface charge can be achieved, for example, by metering in the cationic, salt-like, ethylenically unsaturated quaternary monomers, preferably alkylammonium compounds, mentioned above under b) in uneven amounts, preferably larger amounts, with the monomer mixture at the start of the copolymerization .
• the cation activity and the cationic surface charge fraction can be measured, for example, titrimetrically in a known manner (cf. W. Schempp and HT Trau, Kliblatt für Textilfabrikation 19, 1981, pp. 726-732, or JP Fischer and K. Lschreib in GD Parfitt and AV Patsis, Organic Coatings: Science and Technology, Vol. 8, pp. 227-249, Marcel Dekker, Inc., New York, April 1986).
• the solids content (FS) of the cationic plastic dispersions used according to the invention is in the range customary for dispersions.
• the solids content is preferably set to values of 3 to 40% by weight, in particular 5 to 20% by weight, based on the plastic dispersion.
• the cationic dispersions according to the invention have a low viscosity and develop practically no disruptive foam when used.
• the dispersion copolymers which can be isolated from the aqueous cationic plastic dispersions used according to the invention are not soluble in water.
• cationic plastic dispersions by free-radically initiated emulsion polymerization in an aqueous medium, all systems customary in emulsion polymerization, preferably water-soluble, and initiating free radical chains, which can also be anionic in nature, can be used to initiate the copolymerization.
• Preferred initiators are e.g. 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) dihydrochloride, 4,4'-azobis (4-cyanovaleric acid), H2O2, tert.
• persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate, redox systems such as H2O2 / ascorbic acid, optionally with the addition of small amounts of polyvalent metal salts, such as.
• B. iron (II) sulfate as an activator, also high-energy radiation and conventional photoinitiators.
• Azo compounds such as 2,2'-azobis (2-amidinopropane) dihydrochloride and 4,4'-azobis (4-cyanovaleric acid) are preferably used.
• the Emulsion polymerization also includes conventional regulators, such as mercaptans or halogenated hydrocarbons for lowering the molecular weight, or optionally up to 5% by weight, based on the total amount of monomers, of polyethylenically unsaturated or polyfunctional compounds capable of crosslinking, such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, butane diisocyanate Butanediol diacrylate, triallyl cyanurate, melamine, isocyanatoethyl methacrylate can be used to increase the molecular weight.
• regulators such as mercaptans or halogenated hydrocarbons for lowering the molecular weight, or optionally up to 5% by weight, based on the total amount of monomers, of polyethylenically unsaturated or polyfunctional compounds capable of crosslinking, such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacryl
• paper test sheets are produced from base paper treated with the sizing agent to be tested in the usual way (production according to leaflet V / 8/116 of November 26, 1976 by the Association of German Pulp and Paper Chemists and Engineers).
• the test sheets are dried on a steam-heated cylinder dryer with felt covering.
• the test sheets are dried in a drying cabinet at 120 ° C for 10 minutes.
• the sizing factor f is determined from the glued test sheets obtained, which can be calculated using the following formula I:
• the quantity "time” contained in the formula I is the time in seconds that a test ink (according to DIN 53 126) needs to act on the paper under constant pressure and without inhibitory influences from the first touch to the first sign of penetration of the paper sample . It is determined with the aid of the glue level testing device PLG-e (Schröder, Weinheim), which registers the reflectivity, which changes as a result of the penetration of the ink into the paper, photoelectrically as a function of time.
• the dry and wet fracture resistance [N] are determined in accordance with DIN 53112, but the washing time is reduced from 24 hours to 1 hour.
• the bursting strength according to Mullen can be determined according to DIN 53 141.
• MATAC methacrylamidopropyltrimethylammonium chloride
• demineralized water demineralized water
• FS solids content
• T G glass transition temperature of the copolymer
• MFT minimum film formation temperature
• Example 1 is repeated, but with different changes. So the proportions are varied in the comonomers and it is used as a polymerization initiator instead of the [Cu (NO3) 2 + H2O2] catalyst equivalent amounts of 4,4'-azo-bis (4-cyanovaleric acid) (AVS) and the respective monomer mixture added.
• AVS 4,4'-azo-bis (4-cyanovaleric acid)
• Example 1 is repeated with the modification that the quantitative ratios of the comonomers vary and the methyl methacrylate is omitted entirely.
• the same polymerization initiators as in Examples 2 to 4 are used.
• the numerical values are summarized in Table 1.
• the resulting cationic copolymer dispersion is not in accordance with the invention since, among other things, it has a too high T G of 73 ° C. In addition, the external cation activity is too low.
• TABLE 1 Cationic copolymer dispersions Example No. Proportion of monomer units in the copolymer and proportion of auxiliaries (% by weight) Dispersion properties Methyl methacrylate Butyl acrylate Styrene MAPTAC 1) N-MAA 2) Emuls.
• aqueous cellulose pulp is first mixed with the poly-DADMAC as an aqueous solution with stirring and the aqueous cationic copolymer dispersion is then metered in with stirring and the base paper test sheets are obtained and conditioned in a conventional manner.
• the simultaneous addition of both agents (retention aid and aqueous cationic copolymer dispersion) via separate feeds gives practically the same advantageous results.
• the sizing factor (f), the wet breaking resistance [N] and the dry breaking resistance [N] are determined on the raw paper test sheets obtained. The results are summarized in Table 2.

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• 1989
  • 1989-09-02 DE DE3929226A patent/DE3929226A1/de not_active Withdrawn
• 1990
  • 1990-08-28 EP EP90116422A patent/EP0416427B1/fr not_active Expired - Lifetime
  • 1990-08-28 ES ES90116422T patent/ES2050322T3/es not_active Expired - Lifetime
  • 1990-08-28 DE DE90116422T patent/DE59004595D1/de not_active Expired - Fee Related
  • 1990-08-30 FI FI904273A patent/FI904273A0/fi not_active Application Discontinuation
  • 1990-08-31 JP JP2228530A patent/JPH0397995A/ja active Pending
• 1995
  • 1995-02-23 US US08/393,457 patent/US5518585A/en not_active Expired - Fee Related

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