FI60025B - FOER FARING FRAMSTAELLNING AV MED KETENDIMER LIMMAT PAPPER OCH KARTONG - Google Patents

Description

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Patent- och reglfterstyrelten Amttkan uthgd ocb utUkrifcn publk.rad 31.07 · oi (32) (33) (31) Pyy4 «ny« tuelkMt — B * jlrd priority 20.10.71

England-England (GB) 2 + 8856/71 (71) Hercules Limited, 20, Red Lion Street, London WC1R liPB,

Englant i-England (GB) (72) Thomas Edward Anderson, West Mailing, Kent, England-England (GB) (7 * 0 Oy Kolster Ab (5 * +) Method for making paper and board glued with a ketide dimer -Förfarande för framställning av med ketendimer limmat papper och karton

The invention relates to the production of glued paper or paperboard and in particular to a process for the production of glued paper or paperboard and to a new adhesive combination suitable for use in this process.

In the manufacture of paper and board, it is common to add an adhesive to the pulp slurry shortly before forming the paper web (this is known as "internal sizing") or to treat the formed paper or board with a sizing agent (known as "external sizing"). Until now, the most commonly used sizing agents have been resin and starch, but in recent years ketene dimers have increasingly been used as sizing agents in industrial practice for both internal and external sizing. Ketene dimers are normally used in the form of their aqueous emulsions, the emulsion being formed by a dispersant which is a nonionic or, more usually, a cationic emulsifier such as cationic starch. Such ketene dimer emulsions are described, for example, in GB Patents 706 5 ^ 3 and 903 Ul6.

2,60025 When ketene dimers are used as internal sizing agents in the manufacture of cellulosic paper from fibrous webs, the reaction between the ketene dimer and the cellulose during drying of the paper and continuous in the dry paper is assumed. By performing certain tests on the paper, it is possible to predict the degree of gluing that can finally be expected from the paper. Because papermakers do not accept paper with a degree of sizing immediately below the paper machine, well below the required value, and rely on the degree of sizing to improve over time, it is normal to use excess ketene dimer sizing to produce paper with the desired or predominantly desired degree of sizing before aging. Another reason for the normal use of excess ketene dimer is to provide sufficient water resistance to the first part of the dry end of the paper machine to facilitate other treatments of the paper web prior to final drying, such as aqueous solutions, emulsions or suspensions used in surface sizing and machine coating. If gluing is not sufficient at this stage, excessive water uptake will occur and, in the case of light paper, there is a possibility of serious deterioration of the web. Excess water must also be dried off, which increases the load on the after-dryers, thus increasing the steam consumption and reducing the speed of the machine.

The invention relates to a method for improving the sizing efficiency of ketene dimer sizing agents, whereby the above-mentioned disadvantages in the use of such sizing agents can be avoided or at least reduced and the overall efficiency of the ketene dimer sizing agent can be increased. The invention further relates to a new sizing composition based on ketene dimer sizing agents.

It has been found that the addition of a particular group of color fasteners simultaneously with a ketene dimer sizing agent can result in a significant increase in the sizing power of the ketene dimer sizing agent so that a paper machine can achieve a higher degree The color fixing agents can be, for example, water-soluble dicyandiamide-formaldehyde condensation products.

The invention relates to a process for the production of glued paper, board or cardboard from a cellulosic pulp, in which a cationic polymer and a ketene dimer sizing agent characterized in This gives a glued paper or board with a gluing degree of 6 ° C 2 5 3 higher than that which would have been obtained using the same amount of ketene dimer sizing agent without dicyandiamide formaldehyde condensate a. This condensate is, of course, added in an amount sufficient to increase the leaching effect of the ketene dimer. In general, the amount of color fixing agent to be added to the cellulose pulp is in the range of 0.05 to 2.0% by weight based on the dry weight of the cellulose pulp, while the amount of ketene dimer ranges from 0.02 to 1.0% by weight based on the dry weight of the cellulose pulp.

In practice, the ketene dimer sizing agent and the color fixing agent can be added to the cellulose pulp simultaneously to simplify the papermaking process, and this can most easily be done by adding a mixture of both the ketene dimer sizing agent and the color fixing agent. In addition to simplifying the process, the use of such mixtures increases the gluing efficiency compared to what is achieved by adding its two components separately.

Accordingly, another object of the invention is an adhesive composition comprising a ketene dimer sizing agent and a color fixing agent which is a dicyandiamide-formaldehyde condensate.

The sizing composition of the invention is generally used in the form of an aqueous emulsion containing a suitable emulsifying agent. The term "emulsion" is used herein to mean a liquid-liquid type or a solid-liquid type dispersion.

The emulsifier used may be selected from emulsifiers conventionally used in the preparation of ketene dimer adhesive emulsions. Such enulsifiers include cationic starches, which are water-soluble starches with sufficient cationic amino, qualifying ammonium, or other cationic groups to render the starch as a whole adherent to cellulose. An example of such a cationic starch is a cationic amine-modified starch as described in the aforementioned GB Patent Publication 903 U16.

Alternatively, a water-soluble cationic thermosetting resin obtained by reacting a water-soluble polyamide formed by a dibasic carboxylic acid and a polyalkylene polyamine containing 2 to 8 alkylene groups with epichlorohydrin can be used as the emulsifier. The polyamide used in the preparation of the resin may be a saturated aliphatic dibasic carboxylic acid containing 3 to 10 carbon atoms and a polyalkylene polyamine as described, for example, in GB 865,727. Preferably, a saturated acid having U-6 carbon atoms, 60025 l namely succinic, glutaric or adipic acid, Diglycoic acid can also be used. Alternatively, the polyamide may be formed using an aromatic dicarboxylic acid, for example terephthalic acid, isophthalic acid or phthalic acid, or an β-unsaturated dicarboxylic acid, for example maleic acid, fumaric acid, itaconic acid, glutaconic acid, citraconic acid or mesacaconic acid.

The temperatures used to react the dibasic acid and the polyalkylene-polyamine can range from about 10 ° C to about 290 ° C at atmospheric pressure. Temperatures in the range of about 160-210 ° C are preferred. When reduced pressures are used, slightly lower temperatures can be used. The reaction time depends on the temperatures and pressures used and usually ranges from 1/2 to 2 hours.

When carrying out the reaction, it is preferred to use an amount of dibasic acid sufficient to react substantially completely with the primary amine group of the polyalkylene-polyamine, but insufficient to react with the secondary amine group in any substantial amount.

This usually requires a molar ratio of polyalkylene polyamine to dibasic acid of about 0.9: 1 to about 1.2: 1. However, molar ratios from about 0.8: 1 to about 1, U: 1 can be used.

Examples of suitable polyalkylene polyamines that can be used to make the water-soluble polyamide include diethylenetriamine, triethylene tetramine, tetraethylenepentamine, and dipropylene triamine.

The polyamide formed as described above is then converted to a cationic thermosetting resin by reacting it with epichlorohydrin at a temperature between about 1 * 5 to about 100 ° C and preferably between about L5 ~ 70 ° C until 20% of the dry matter the viscosity of the solution containing 25 ° C has reached C or more on the Gardner-Holdt scale. This reaction is preferably carried out in aqueous solution to control the reaction.

When the desired viscosity is reached, sufficient water is added to adjust the dry matter content of the resin solution to about 10% or less, the product is cooled to about 25 ° C, and then stabilized by adding sufficient acid, such as hydrochloric acid, to lower the pH to at least about 6. and preferably at least about 5.

The ketene dimer used as an adhesive in this invention is normally a higher ketene dimer represented by the general formula: RCH = C = 0 ~ | 2,50025 wherein R is a hydrocarbon radical selected from alkyl groups having at least 8 carbon atoms, cycloalkyl groups having at least 6 carbon atoms, aryl, aralkyl and alkaryl groups. Preferably the radical R is an alkyl group having at least 8 carbon atoms, preferably hexadecyl and / or tetradecyl.

The dicyanamide-formaldehyde condensation products used as color fasteners in this invention are water-soluble thermosetting reaction products obtained from the reaction between dicyanamide, formaldehyde and ammonium salt. The term "formaldehyde" is used herein to mean not only formaldehyde itself but also formaldehyde in the form of 30-10% aqueous solutions and polymeric forms of formeddehyde, such as para-formaldehyde and trioxaem. Chemical compounds that can release formaldehyde by heating or acidification, for example acetyls or hexamethylenetetramine, can be used as precursors for formaldehyde, if desired.

The reactive ammonium salt is a water-soluble salt of ammonia or a salt of an amine and an acid. Particularly preferred salts are those of the formula (NH 2, X; (RNH 2) n X; or (R 2 H 2) x, wherein R and R 'are each an alkyl radical having 1 to U carbon atoms, for example methyl, ethyl , propyl, isopropyl or n-butyl, X is an acid anion, for example Cl, Br, J, SO 2 -, CH 2 COO, NO 2 or PO 4 - and n is an integer equal to the charge of the anion. , when X is SO 2, is n 2, when X is Cl, is n 1, and when X is PO 2 =, is n 3 · Specific ammonium salts include ammonium sulfate, ammonium chloride, methylammonium chloride, dimethylammonium chloride, ethylammonium sulfate and ammonium acetate.

Other suitable ammonium salts include (1) a polyamine of the formula:

R

wherein R is hydrogen or methyl; n is an integer from 2 to 6 and x is an integer from 0 to 3, and (2) water-soluble salts of an acid such as sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid or acetic acid. Specific examples of such polyamines include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and bis (3-aminopropyl) amine.

Methods for preparing condensation products from the above reactants are well known. The following is a preferred method.

I.

, 60025 6

About 1 mole of dicyandiamide and about 3 1 moles of about 1 1/2 moles of formaldehyde are placed in the reaction vessel. Water is suitably used as the reaction medium and sufficient water should be present in the mixture to give an aqueous reaction mass which can be easily stirred under the reaction conditions. The amount of water to be used can be readily estimated by one skilled in the art. The aqueous mixture is heated to boiling after the team (about 95-105 ° C) and refluxed for about 15-30 minutes, or longer if desired. The ammonium salt is then added in an amount such that about 0.8 to about 1.2 equivalents, preferably about 1 equivalent, of basic nitrogen is present in the reaction mixture. The resulting mixture is heated to reflux and maintained at this temperature until substantially all of the nitriles (-C = N) present have reacted. This can be easily and quickly determined by infra-red analysis. The time usually takes 2-b hours.

About 1.25 to about 3.75 moles of formaldehyde are then added to the reaction mass. The resulting mixture is heated to reflux until an aqueous solution of the resinous reaction product having a dry matter content of about 50 to about 60 has a viscosity of about G to X on a Gardner-Holdt scale (measured at 25 ° C) and preferably S from to X.

If desired, water-soluble thermosetting condensation products can also be obtained by preparing a mixture of all of the above ingredients in the above amounts (using water as the reaction medium above), boiling the mixture and refluxing until an aqueous solution of the resin reaction product has a dry matter content of about 50%. 60%, the viscosity is from about G to X, preferably from S to X on the Gardner-Holdt scale (measured at 25 ° C).

The present invention uses a color fixative and a ketene dimer in a weight ratio of about 10: 1 to about 1:10.

Preferred aqueous emulsions of this invention contain essentially, by weight, (i) from about 3 to about 30 parts solids and (II) from about 97 "to about 70 parts water, the sum of (I) and (II) being 100 parts The solids consist essentially, by weight, of (a) about 1 to 12 parts of the ketene dimer, (h) about 1 to 25 parts of the dicyandiamide formaldehyde ammonium salt condensation product, and (c) about 1 to 25 parts of the emulsifier, wherein the amounts of (a), (h ) and (c) are selected to have a total weight of between 3 and 30 parts.

The sizing composition of the invention can be prepared by mixing together a color fixing agent and a ketene dimer sizing agent, preferably in the form of an emulsion. The mixing is carried out, for example, in a vessel equipped with mixing devices.

τ 60025

If it is desired to accelerate the sizing rate obtained with the sizing composition of the invention, this can be done by pretreating the cellulosic pulp with a cationic polyelectrolyte, for example a color fixing agent such as dicyanodiamide formaldehyde condensate, as explained above.

When using the sizing composition of the invention, it is possible in certain cases to cope without subsequent addition of retention aids which are usually used immediately before forming the paper web, as it has been found that the sizing composition itself has sufficient stability in the papermaking system to act as a retention aid.

It should be noted that while the sizing composition of the invention is primarily preferred when used for internal sizing, it can also be used in external sizing methods if desired. Thus, the sizing composition can be applied to the surface of the finished paper web, for example, by means of a sizing press, a coating device or a spray diffuser. The sizing composition may be applied with water or mixed with a starch suitable for surface treatment or as part of a liquid system for coating.

The following examples illustrate the invention.

Example 1

An aqueous ketene dimer emulsion was prepared from a mixed tetradecyl / hexadecyl ketene dimer (prepared from a mixture of tin and stearic acids) and dimethylaminoethyl potato starch, the emulsion containing 6 wt% dimer and 3 wt% cationic amine.

This emulsion (referred to herein as "Emulsion A" for comparison purposes of Example 6) was mixed in a volume ratio of 00:20 with a commercially available color fixative based on the dicyanodiamide-formaldehyde condensation product and marketed by I.C.I. Limited 50 as a silicon aqueous solution under the tradename Fixanol PN (now known as Perminal FC-P), in a container equipped with mixing devices to prepare the required sizing composition.

Example 2

The aminopolyamide was formed by slowly adding 219.3 parts by weight of adipic acid, stirring to 151.3 parts by weight of diethylenetriamine in a flask equipped with a stirrer and condenser to collect aqueous distillates. The reaction mixture was stirred and heated at 170-180 ° C under a nitrogen atmosphere until amide formation was complete. After air cooling to about 100 ° C, hot water was added with stirring to prepare a 50% solids polyamide resin solution having a specific viscosity of 0.11 + 0 measured using a 2 # solution when the solvent was 1N NH 4 Cl solution. An epichlorohydrin derivative of aminopolyamide was prepared by adding 150 parts by weight of water to 50 parts by weight of a solution containing 50% solids and then adding 13.7 parts by weight (0.11 + 9 moles) of epichlorohydrin. The reaction mixture was heated to 70 ° C with stirring and reflux until the Gardner-Holdt viscosity reached D. Sufficient water was added to give a dry matter content of about 10%. Sulfuric acid was then added to adjust the pH of the solution to about 5 to obtain the required aminopolyamide epichlorohydrin resin solution.

An aqueous ketene dimer emulsion was prepared from a mixture of 6 parts by weight of a mixed tetradecyl / hexadecyl ketene dimer (prepared from a mixture of palmitic and stearic acids) and 60 parts by weight of a water-soluble cationic aminopolyamide-epichlorohydrin resin solution described above. The mixture was heated to 60 ° C and kept there until the dimer had melted, after which it was dispersed by stirring. The mixture was then homogenized and the resulting emulsion was cooled to 1 + 0 ° C. This emulsion is referred to as "Emulsion B" for the reference purposes of Example 6.

This emulsion was then mixed in a volume ratio of 80:20 with the commercially available color fixative Fixanol PN, as in Example 1, to form the required adhesive combination.

Example 3

A conventional Fourdrinier paper machine was used to make glued paper using a normal set of mechanical operations. This machine was also equipped with a coating system by which the dried paper is subjected to another finishing operation, namely the application of a slurry or coating containing alumina and various organic binders as a pigment to its surface.

After the pulp was disintegrated and ground to a thick pulp with a consistency of 3% t, 2.27 kg / ton of the commercially available color fastener Fixanol PN was added continuously through the pulp gate in the headbox.

1.36 kg / tonne (calculated as ketene dimer) of an aqueous ketene dimer emulsion, prepared from a mixed tetradecyl / hexadecyl ketene dimer (prepared from a mixture of palmitic and stearic acids) and dimethylaminoethyl potato starch and 3 modified starch, was then added to the pulp as an adhesive at the inlet of the first vane pump immediately before the hydrocyclone 9 60025 pulp purifiers. After further dilution with the second vane pump, the pulp was as explained in Example 2, the aqueous solution was then added at this point as a retention aid to both the fiber and the filler. The web was then formed on a machine wire, pressed, dried and coated. After further drying, the paper was calendered and rolled in the usual manner.

The paper web was tested immediately after entering the machine and, in addition, random samples were taken from the dried paper web before coating. In each case, the degree of sizing was determined and fiber and filler retention tests were performed to determine the standard retention level.

Three hours after sufficient assurance that the system was in equilibrium, the addition of Fixanol PN to the mass port headbox was stopped and the ketene dimer adhesive was replaced with the same amount of adhesive combination prepared according to Example 1 above. This change resulted in an improved gluing level, so that the amount of glue combination added was reduced to achieve the initial gluing level at equilibrium conditions. The final addition rate was then 0.91 kg / ton calculated as the ketene dimer. Thereafter, the addition of the retention enhancer was stopped without changing the retention level, as observed by additional retention tests. This represented a 33% saving in the addition of the ketene dimer.

The procedure described above was then repeated under similar conditions, but with an adhesive combination prepared as described in Example 2 instead of the adhesive combination of Example 1. The amount of addition was originally 0.91 kg / ton, calculated as ketene dimer. No retention aid was used. As above, the degree of sizing improved and the amount of addition was reduced until the initial level of sizing was reached under equilibrium conditions. The amount of addition was then 0.1 + 5 kg / ton, calculated as ketene dimer, which represented a 66% saving in the addition of ketene dimer. As shown above by the retention tests, the retention level remained within the norms.

The above example shows a reduction in the amount of ketene dimer added and the removal of the retention aid, while the adhesion level and the retention level remain unchanged which can be achieved by the method and adhesive combination of the present invention.

Example 1+

An aqueous ketene dimer emulsion was prepared from a mixed tetradecyl / hexadecyl ketene dimer (prepared from a mixture of palmitic and stearic acids) and dimethylaminoethyl potato starch, the emulsion containing 6% by weight of? dimer and 3% by weight of cationic amine-modified starch.

The dicyanamide formaldehyde condensation product useful as a color fixative was prepared by refluxing 27.3 parts by weight of dicyandiamide with 27.2 parts by weight of a 37% (w / v) formalin solution at 101 ° C in a vessel equipped with a cooling system. The temperature was reduced to 45 ° C using a cooling system equipped with a vessel. 15.2 wt% ammonium chloride was added slowly over 20 minutes and then the temperature was raised to 110 ° C for one hour, after which the mixture was refluxed for another hour. After cooling to 75 ° C, an additional 33.9 parts by weight of a 37% formalin solution was added and the temperature was further reduced to 60 ° C. The resulting liquid was filtered to obtain the desired liquid condensation product.

The ketene dimer emulsion was then mixed with the condensation product in a volume ratio of 80:20 in a vessel equipped with mixing devices to form an adhesive combination.

Example 5

A ketene dimer emulsion was prepared from a mixed tetradecyl / hexadecyl ketene dimer (prepared from a mixture of palmitic and stearic acids) and the aminopolyamide-epichlorohydrin resin described in Example 2. The emulsion contained, by weight, 6 # dimer and 6 # resin.

This ketene dimer emulsion was mixed in a volume ratio of 80:20 with dicyano-diamide-formaldehyde condensation product prepared as described in Example t while mixing in a vessel equipped with mixing devices to form an adhesive combination.

Example 6

To compare the gluing performance of the adhesive combinations prepared according to the invention with the corresponding known adhesive combinations which do not contain dicyanamide formaldehyde condensation products, the following test was performed:

Lahorator test sheets were prepared with Noble Wood from Wargen softwood sulfite pulp ground to 43 ° Schopper Riegler. The ground mass with 1 if% English China clay kaolin grade I, based on the amount of fibers, was adjusted to a dry matter content of 0.28 # in the dispenser of the apparatus and mixed well. The adhesive combination to be tested was added to the portion in a mass of 11,60025 dispensers in an amount such that the ratio of ketene dimer to cellulose fibers was 0.12-100. A laboratory test sheet was made from each pulp sample by the standard method. After sheet formation, the sheet was dried, separated from the wire cloth, and its degree of gluing was determined by the 1-minute Cobb test (TAPPI standard T Utl). Only a portion of the sample sheet was used for this test, and the final sheet was examined at 60% relative humidity (R.H.) and 20 ° C for 2 hours after being kept naturally maturable, gluing properties in the same manner.

The results obtained are shown in the following table:

Table

Adhesive combination Cobb test gluing results ^ l min. after (given in grams of water taken with 1 m of paper)

Immediately after drying after 2 hours at 20 ° C and 60%. humidity

Emulsion A 57 51

Combination of Example 1 37 33

Combination of Example 4 1 * 7 1 * 0

Emulsion B 50 50

Combination of Example 2 39 35

The combination of Example 5 1 * 3 1 * 0

The table above clearly shows the significant improvement achieved with the dicyandiamide formaldehyde condensation product present.