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
  • D21H17/03—Non-macromolecular organic compounds
  • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
  • D21H17/17—Ketenes, e.g. ketene dimers

Definitions

• This invention relates to novel compositions comprising ketene dimers and to processes for their production.
• Ketene dimers find use as ingredients of paper sizing compositions.
• the sizing compositions are manufactured in the form of relatively concentrated aqueous dispersions which are diluted before use in the paper sizing process.
• the concentrated aqueous dispersions suffer from the disadvantage that their efficiency as paper sizing agents deteriorates on prolonged storage apparently because of the hydrolysis of the ketene dimer.
• ketene dimers are dispersed in water in the presence of from 0.2 to 2.5% by weight of the weight of ketene dimer of a surfactant and/or an emulsifier. Attempts to dry such dispersions in the past have not been successful.
• the ketene dimer tends to hydrolyse. If the dispersion is dried at high temperatures the ketene dimer tends to char. If the dispersion is spray dried the material dries to a sticky mass which is difficult to handle.
• the ketene dimers which are useful as paper sizing agents are compounds having the molecular formula: wherein R represents an alkyl, alkenyl, aryl or alkaryl group comprising from 8 to 24 carbon atoms. Preferably R represents an alkyl group having from 8 to 20 carbon atoms. These dimers are normally prepared from fatty acids obtained from natural sources and therefore comprise a mixture of dimers wherein the number of carbon atoms in the substituent group R varies. Mixtures of ketene dimers wherein R has an average value of from 8 to 24 are useful in the processes of this invention. Preferably the group R contains an average of from 12 to 18 and more preferably from 14 to 18 carbon atoms.
• ketene dimers include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, phenyl, benzyl, beta-napthyl and cyclohexyl keten dimers, as well as the ketene dimers prepared by known methods from montanic acid, naphthenic acid, 9 .
• the ketene dimers are manufactured in the form of waxy solids comprising the ketene dimers in admixture with up to 20% by weight of impurities. These products are normally used as such, i.e. without separation of the impurities.
• all references to ketene dimers include mixtures thereof with these impurities and all proportions based on the weight of ketene dimer are based upon the weight of the manufactured product.
• the encapsulating agent should be selected so as to be effective in enabling the dispersion to be dried to form a product which is redispersable in water and thereby useful in paper sizing processes.
• the nature of the encapsulating agent should be such that it is compatible with the other components of the spray dried product and such that it is not degraded during the drying process.
• Examples of compounds which may be useful as encapsulating agents are: gelatin, tristearin, gum arabic, sugars, ethyl cellulose, carboxymethylcellulose, polyacrylamides, silicates, polyethers, polyesters, polyamides, starches especially cationic starches and polyvinyl alcohol.
• the amount of encapsulating agent which is employed is proportional to the amount of ketene dimer in the dispersion and will normally be adjusted so as to be just sufficient to enable the dispersion to be dried. The use of excess quantities of encapsulating agent is less preferred. Normally the quantity of encapsulating agent which is added to the dispersion will be from 25 to 100%, preferably from 25 to 75% by weight of the weight of ketene dimer present in the dispersion.
• a preferred class of encapsulating agent are those which are known to be useful as ingredients of paper sizing compositions. Such agents may be employed in larger quantities than are required to sucessfully encapsulate the dimer since they make a contribution to the efficiency of the dried product used in the paper sizing process.
• Such agents are starches such as cationic starches.
• a particularly preferred class of encapsulating agents are those which are known to disperse in cold water the preferred examples being certain cationic starches such as those sold under the Trade Marks Solvitose NX and Perfectamyl PLY.
• the encapsulating agent can be added to any aqueous dispersion of the ketene dimer. However it is strongly preferred to add the encapsulating agent to a dispersion which is itself useful as a paper size so that redispersion of the dried product produces a dispersion which is useful as a paper size without the need to disperse any additional components in order to form the size.
• Ketene dimer dispersions normally comprise at least one surfactant and the presence of a surfactant in the dried product facilitates the redispersion of the product in the paper sizing process.
• suitable surfactants are the sodium salts of naphthalene formaldehyde sulphonate condensates, an ester of polyoxyethylene sorbitan or a sodium lignosulphonate.
• the amount of surfactant added will usually be in the range 0.3 to 3.5% by weight of the ketene dimer, preferably in the range 1.25 to 2.5%.
• the ketene dimer dispersions used in the spray drying processes may further comprise other conventional ingredients such as emulsifiers, stabilisers, retention aids and slimicides although the use of compounds which are sensitive to heat is preferably avoided.
• the ketene dimer dispersions preferably comprise a cationic polymer such as a polyamine in order to increase the efficiency of the dispersion as a paper size.
• a cationic polymer such as a polyamine
• examples of polymers useful in this application water soluble polyamino polyamide- epichlohydrin resins, alkylene polyamine epichlorhydrin resins, poly (diallylamine)-epichlorhydrin resins, poly dialkyl dimethyl ammonium chloride and polyethyleneimines.
• the amount of polymer present may be up to a weight ratio of ketene dimer to polymer of 1.0:1.0. However as the quantity of polymer increases there is an increasing tendency to produce a relatively sticky product and it is preferred that the weight ratio of ketene dimer to polymer is in the range 1.0:0.2 to 1.0:0.5.
• the dispersion of the ketene dimer and the encapsulating agent can be dried by a variety of techniques. However exposure of the dimer to high temperatures for long periods can lead to its degradation either by charring or by hydrolysis and is best avoided. Techniques such as freeze drying and spray drying are preferably employed. We prefer to utilise spray drying although the conditions under which the drying is carried out must be monitored in order to minimise degradation of the ketene dimer. The spray drying of the ketene dimer dispersions can be carried out using conventional equipment. The temperature of the drier should be controlled so as to avoid any significant amount of charring or degradation of the components of the emulsion.
• the temperature at the inlet to the dryer should be in the range 220 0 to 350 o C and that at the outlet of the dryer 110 0 to 125°C.
• the drying process is carried out so as to produce a powdered product comprising less than 0.1% by weight of water.
• the powder products must be dispersed in an aqueous medium in order to be useful in paper sizing processes.
• the powder will be diluted with up to ten times its weight of water. Adequate dispersion is preferably obtained using vigorous agitation.
• composition 1 A dispersion of a stearic/palmitic alkyl ketene dimer having the following composition (Composition 1) was prepared.
• a cationic starch product as sold under the Trade Mark Perfectamyl PLV was added to one sample of the dispersion in a quantity such that the ratio of the weight of ketene to starch was 1:1 (Composition 2).
• the same cationic starch product was added to a second sample of the dispersion in a quantity such that the ratio of the weight of ketene dimer to starch was 1:0.5 (Composition 3).
• compositions 2 and 3 were then spray dried using a Niro Production Minor Spray Drier set for Rotary Atomisation using an atomiser speed of 24,000 rpm.
• the liquor feed temperature was 15 0 C
• the drier inlet temperature was 250 0 C
• the drier outlet temperature 125°C.
• the product was a white powder.
• Trials G and H are based on a product (Composition 4) with a surfactant content on ketene dimer of 0.62% but which are otherwise identical with and are manufactured under the same conditions as composition 3 described above.
• Trial J is based on a product (Composition 5) with a ;urfactant content on ketene dimer of 2.8% but which is otherwise identical with and is manufactured under the same conditions as composition 3.
• composition 6 A dispersion (composition 6) of a stearic/palmitic alkyl ketene dimer having the following composition was prepared:-
• a cationic starch product as sold under the Trade mark Solvitose NX was added to this dispersion in a quantity such that the ratio of the weight of ketene dimer to starch was 1:0.5 (composition 7).
• composition 7 was then spray dried using the conditions set forth in Example 1. The efficiency of sizing of compositions 6 and 7 was then assessed at that time and after storage at ambient temperatures for 3.5 and 4.5 months. The results were as follows:-

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• 1985
  • 1985-10-23 GB GB858526158A patent/GB8526158D0/en active Pending
• 1986
  • 1986-10-21 FI FI864251A patent/FI86317C/fi not_active IP Right Cessation
  • 1986-10-23 DE DE8686308244T patent/DE3676428D1/de not_active Expired - Fee Related
  • 1986-10-23 EP EP86308244A patent/EP0220941B1/de not_active Expired - Lifetime
  • 1986-10-23 JP JP61250940A patent/JPS62125094A/ja active Pending
  • 1986-10-23 ES ES86308244T patent/ES2020661B3/es not_active Expired - Lifetime
  • 1986-10-23 AT AT86308244T patent/ATE59681T1/de active
• 1987
  • 1987-09-23 MY MYPI87001903A patent/MY102764A/en unknown

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