GB1588416A

GB1588416A - Process and compositions for the treatment of cellulosic materials

Info

Publication number: GB1588416A
Application number: GB37157/76A
Authority: GB
Original assignee: Laporte Industries Ltd
Current assignee: Evonik LIL Ltd
Priority date: 1976-09-08
Filing date: 1976-09-08
Publication date: 1981-04-23
Also published as: SE7710058L; JPS5335087A; FR2364288A1; IT1091129B; FI772539A; DE2740314A1

Description

(54) A PROCESS AND COMPOSITIONS FOR THE TREATMENT OF CELLULOSIC MATERIALS (71) We, LAPORTE INDUSTRIES LIMITED, a British Company of Hanover House, 14 Hanover Square, London, W. 1. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for the treatment of cellulosic materials, and to the provision of compositions for use in such a process.

In British Patent Application No. 59301/73, Serial No. 1,496,879, we have described compositions for use in treating cellulosic materials, and more specifically in sizing paper and water proofing textiles. Such compositions contain as the active sizing or waterproofing ingredient a cyclic imide N-substituted by a hydrophobic acyl radical, which we believe reacts with the paper of textile, thereby chemically bonding the hydrophobic radical to the paper or textile.

For convenience, in the present specification, we have abreviated the term "cyclic imide Nsubstituted by an hydrophobic acyl radical" to the term "cyclic imide".

Conventionally, compositions of reactive organic compounds for treating cellulosic material comprise either organic solutions or aqueous emulsions of the active ingredient.

Processes for sizing paper internally, i.e. so called engine sizing, normally employ aqueous emulsions, the aqueous emulsion being contacted with the paper pulp in the paper making machine prior to drying the resultant paper.

Clearly, it is desirable for the emulsions to contain comparatively high concentrations of active ingredient and other ingredients e.g.

retention aids, so as to minimise the volume of emulsion that needs to be stored, transported or pumped at any given time. However, we have found that emulsions containing comparatively high concentrations of cyclic imides together with, in particular, cationic starches used as retention aids, tend on formation or after storage to be somewhat viscous, making them difficult to pump or pour.

It is an object of the present invention to provide emulsions having reduced viscosity which contain cyclic imides.

According to the present invention there is provided a composition for treating cellulosic materials in the form of an aqueous emulsion of a cyclic imide N- substituted by an hydrophobic acyl radical as herein defined, and a cationic starch, the emulsion containing from 0.5 to 3.0% by weight of a formaldehyde condensation product of sodium naphthalene sulphonate, based on the weight of the starch.

According to a second aspect of the present invention there is provided a process for treating cellulosic material comprising the steps of contacting the cellulosic material with a sizing or waterproofing amount of a cyclic imide Nsubstituted by an hydrophobic acyl radical in an aqueous emulsion containing a cationic starch and from 0.5 to 3.0% by weight based on the starch of the formaldehyde condensation product of sodium naphthalene sulphonate, at a temperature sufficiently high for reaction to occur between the cyclic imide and the cellulosic material.

In the course of our programme of work, we tested two anionic agents which were described in U.S. Patents No. 3,223,543 and 3,223,544 as being incorporated for the purpose of preventing the formation of aggregates in aqueous emulsions containing as retention aid, cationic starches and as reactive sizing agent either fatty acid anhydrides or ketene dimers. The Patentees of said U.S. Patents had sought to prevent formation of such aggregates because their presence resulted in an uneven distribution of active ingredient throughout the emulsion, thereby rendering accurate dosing of the paper pulp to be sized difficult to achieve. The two anionic agents were sodium lignosulphonate and the formaldehyde condensation product of sodium naphthalene sulphonate. In our general experience, aqueous emulsions of cyclic imides appear not to suffer from the problem of aggregate formation, but when the aforementioned anionic agents were incorporated in the emulsions in the amounts exemplified in the two U.S. Patents, formation of aggregates was induced. Furthermore, we found that in general when an anionic agent was incorporated in the emulsion, the sizing or waterproofing effect on the cyclic imide was impaired to at least some extent. Surprisingly, incorporation of a restricted amount of the formaldehyde condensation product of sodium naphthalene sulphonate, which we may refer to hereinafter as FCP, in aqueous emulsions containing a cyclic imide and cationic starch, reduces the viscosity of the emulsion, without inducing formation of aggregates and without substantially impairing the ability of the cyclic imide to size or waterproof. This behaviour, is in marked contrast to that demonstrated when sodium lignosulphonate is incorporated in otherwise identical emulsions, in that the beneficial reduction of viscosity is not observed.

-By-inSorporatng from 0.5 to 3.0% by weight based on the cationic starch of FCP the viscosity of the aqueous emulsion is thereby reduced, the higher the FCP content the more the reduction. Preferably, the FCP content is at least 1.0% by weight based on the starch.

However, as the proportion of FCP to starch increases, the resulting aqueous emulsion becomes increasingly less cationic, as demonstrated by the ionic mobility value of the aqueous emulsion. It has been our experience that, in general, better sizing can be obtained when the aqueous emulsion has an ionic mobility value of substantially zero or is positive. In consequence, we prefer - the aqueous emulusion to contain not more than 2.5% by weight of FCP and in order to achieve a positive ionic mobility value, an FCP content of preferably not more than 2.0% by weight based on the starch. In some particularly preferred embodiments the aqueous emulsion contains from 1.0 to 2.0% by weight FCP, and especially desirably from 1.0 to 1.5% by weight of FCP.

The viscosity of the aqueous emulsion depends on the total solids content which comprises the cyclic imide, the cationic starch and any other emulsifying agents or retention aids which may be employed. Although the weight ratio of cationic starch to cyclic imide can suitably be varied within the general range of from 2:1 to 1:10, the weight ratio is preferably not more than 1:1 and advantageously not less than 1:4. In consequence the cationic starch preferably represents a minor fraction of the total solids content. Conveniently the weight ratio of cationic starch to cyclic imide is not more than 2:3 and desirably is not less than 2:5, a typical weight ratio in the range of 2:3 to 2:5 being 1:2. Desirably, the total solids content of the aqueous emulsion is not more than 15 /O by weight, and preferably is at least 5% by weight. Preferred aqueous emulsions contain at least 5 % by weight cyclic imide and not more than 5% by weight cationic starch. Particularly preferred aqueous emulsions contain from 5 to 7.5% by weight cyclic imide and from 2 to 5% by weight cationic starch, the weight ratio of starch to cyclic imide being in the range of 2:3 to 2:5. In a typical-and highly preferred embodiment the aqueous - emulsion contains 6% by weight cyclic imide and 3 % by weight cationic starch.

A convenient aqueous emulsion contains from 5.5 to 6.5% by weight of cyclic imide and from 2.5 to 4.0% by weight cationic starch. It will be understood that the advantageous and beneficial effect of incorporating from 0.5 to 3.0% by weight of FCP based on the weight of cationic starch can be observed in any of the cyclic imide-containing aqueous emulsions described herein, as can the effect of varying the proportion of FCP within the range 0.5 to 3.0 as described hereinbefore.

The cyclic imide can be any N-hydrophobic acyl substituted cyclic imide, for example compounds represented by the general formula:

wherein R represents a diradical completing an imide ring having 6 or preferably 5 members, and Y represents a hydrophobic radical. Herein by the term hydrophobic radical we mean a radical which terminates at its free end in an uninterrupted chain of at least 11 aliphatic carbon atoms long, which chain is free of hydrophilic substituents. The chain can be bonded directly to the carbonyl carbon atom of the N- substituent or it can be linked indirectly, for example via an amino group. The uninterrupted chain in practice is often solely hydrocarbon and can have side chains (again free of hydrophilic substituents) if desired, and be substituted by hydrophobic groups such as fluoro groups. It will be recognised that the more common hydrophilic substituents include hydroxyl, carboxyl, and sulphonate groups. The uninterrupted chain is preferably from 15 to 21 carbon atoms long, so that the acyl radical is 16 to 22 carbon atoms long when the chain is bonded directly to the carbonyl carbon atom of the N- substituent. Particularly suitable radicals include palmitoyl, stearyl, behenoyl and their unsaturated counterparts, e.g. those derived from oleic and linoleic acids. Where the chain is linked directly, suitable hydrophobic groups include N- (C16 to C22 alkyl) aminopropyl and N-di(Cl6 to C22 alkyl)aminopropyl and aminoethyl analogues.

R can be~ a dimethylene or a tiiiaethylene di: radical or, together with the residue of the imide ring, form a fused bi or polycyclic ring system thus, where R comprises a 6 membered carbocyclic diradical such as a cyclohexane or cyclohexene diradical, the cyclic imide formed comprises a fused bicyclic ring system, and where the cyclohexane or cyclohexene diradical is bridged across the 3 :6 position by a methylene group or an oxygen atom, the cyclic imide formed comprises a fused polycyclic ring system. R can contain ethylenic unsaturation, and can be substituted by one or more aliphatic radicals, including alkyl amino and alkyl groups. Preferably, the cyclic imide is an unsubstituted succinimide, cyclohexane- 1,2-di- carboximide, 4-cyclohexene- 1,2-dicarboximide or a 3,6-endoxo-4-cyclohexene-1,2-dicarboximide.

In practice, the cationic starch is normally a tertiary amino or quaternary ammonium modified starch, which groups confer a positive charge onto starch molecule in an aqueous medium. The cationic starch can be obtained by etherifying a starch with an etherifying agent containing a tertiary amino group, e.g.

dialkylamino alkyl halides. To obtain quater nary ammonium groups, starch containing tertiary amino groups can be treated with, e.g.

an alkyl halide.

Preferably, - the emulsion contains one or more other retention aids such as polyacryl amides optionally copolymerised with un saturated amine salts, polyamides generally, including polyamide-polyamines and polyethyleneamines, and epichlorhydrin conden sates of polyamides. Such other retention aids often incorporate in the aqueous emulsion in an amount from 0.01 to 1.0% by weight and usually in the range of from 0.03 to 0.2% by weight. Alternatively, such other retention aids can be introduced separately from the aqueous emulsion into contact with the cellulosic material. The aqueous emulsion can also contain an emulsifying agent, generally in an amount of up to 5.0% by weight, and in a weight ratio to the cyclic imide of up to 1:2.

Suitable emulsifying agents include sorbitan esters of fatty acids such as polyoxyalkylene derivatives of fatty acid esters of sorbitan, e.g.

polyoxyethylene or polyoxypropylene derivatives of sorbitan monolaurate or monopalmitate or mono or tristearate or mono or trioleate, glycerol esters of fatty acids, polyethylene glycol esters of fatty acids and mono or dialkanolamide derivatives of fatty acids, the fatty acids preferably being lauric acid, palmitic acid, stearic acid or oleic acid.

Alternatively the emulsifying agent can be a polyalkylene oxide block copolymer such as condensates of ethylene oxide or propylene oxide with aliphatic alcohols or alkyl phenols, the aliphatic group preferably containing from 8 to 22 carbon atoms in an aliphatic chain, ex amples being octyl phenol, nonyl phenol, and palmityl, stearyl or oleyl alcohol, or analogous compounds employing long chain aliphatic amines.

Fhe aqueous emulsions described herein can be used to size or waterproof cellulosic material, suitably in the form of cellulose such as cotton, linen or mixtures thereof, or re generated cellulose, or in preferred embodi ments, paper or board. The paper can be in the form of sheets or rolls, or, more conveniently, in the form of aqueous paper stock, often referred to as pulp. The paper or pulp can be virgin or recycled, can have been produced by any conventional process, for example, that produced from or in the form of mechanical pulp, semi-mechanical pulp, or chemical pulp, and can be bleached and semi-bleached or un bleached and can also contain fillers or pigments such as clays for example kaolin, calcium carbonate, titanium dioxide or zinc oxides, and cotton or linen.

Sheets or rolls ot tne paper or other celia- losic material can be contacted with the aqueous emulsion by any conventional process used to impregnate fibrous materials, for ex ample passage of the material through a bath, the amount absorbed being controlled by squeeze rollers, or by brushing, spraying, and roller coating. In such methods the amount of cyclic imide retained by the material depends upon the concentration of imide in the emulsion and the amount of emulsion absorbed by the material. Conventionally, aqueous paper stock is contacted with size during the stage of dis integration of the stock. Polyamide retention aids are preferably added after the disintegra tion stage.

Once the cellulosic material and the emulsion have been brought into contact, the material is allowed to drain, if necessary, and is then dried. The temperature of the drying stage is so selected that the temperature is high enough for the imides to react with the material, but the temperature is not so high that the material is damaged. A typical temperature is in excess of 50"C, and usually at least 70"C. For paper the normal range is from 70"C to 1200C and for textiles from 100It to 150us. It will be recognised, therefore, that the aqueous emulsion as described herein can be employed in currently used machines for making paper or board or for treating textiles.

One of the other characteristics of the aqueous emulsion which can be controlled is its pH. We prefer the aqueous emulsion to have a pH between 3.0 and 4.5, more preferably between 3.5 and 4.5, suitably by the addition as necessary of mineral acids e.g. sulphuric acid, or base e.g. sodium hydroxide.

Some variation in the viscosity of the aqueous emulsion can also be achieved by modi fying the cationic starch, for example by cooking the starch for periods within the range of 1 to 10 minutes with a small amount of mineral acid and or aqueous alkali. Such methods are difficult to control to achieve reproducible results. Other methods suitable for reducing the viscosity of an aqueous emulsion include the use of further and additional homogenisation of the emulsion, but such methods, by introducing additional stage or stages, significantly increase the cost of the process. However, when FCP is incorporated in aqueous emulsions which have been re-homogenised or which incorporate such modified starches an improvement in viscosity coupled with the retention of the ability of the formulation to size or waterproof, is exhibited in the same way as FCP is incorporated in aqueous emulsions containing non-modified starches.

Specific embodiments of the present invention will now be described in greater detail by way of example only.

Example 1.

In this Example each of the emulsions was prepared by the following general method.

First, a litre of water containing 60g cationic starch was heated for 15 minutes at 90"C, to which was added 120 grammes of the cyclic imide N-stearoyl-4-cyclohexene-1,2-dicarboximide with vigorous stirring to form a crude emulsion. The emulsion was then homogenised by passage through an APV Manton Gaulin model 15M-8BA single stage piston homogeniser at 2-3,000 psi and diluted with cold water to give a product containing approximately 6% by weight of cyclic imide, and then cooled to ambient temperature. The viscosity, ionic mobility, total solids content, cyclic imide content and starch content of the aqueous emulsions thus formed were measured in the standard way initially, and the viscosity measured after a period of 1 day and 7 days.

The results are summarised in Table 1 herein below.

The cationic starch included in elnulsions A to E was obtained from Laing National Ltd., who supply it under the trade name CATO 8.

(CATO is a Registered Trade Mark.) Substantially similar results are obtained when other cationic starches are employed.

Emulsion A is present by way of comparison only and emulsions B to E are according to the present invention.

TABLE 1

Viscosity FCP (centipoise) Total Cyclic Wt % solids Imide , Starch (based on Ionic Emulsion Wt. % Wt. % Wt. % starch) Initial 1 day 7 days Mobility A 8.9 5.9 2.9 0 19 30 83 + 1.22 3.3 9.7 6.3 3.3 0.5 23 30 53 +0.77 C 9.0 5.8 3.1 1.0 14 39 44 +0.58 D 8.7 5.6 3.0 1.5 10 12 19 +0.21 iS 8.7 5.5 3.1 2.5 1Q 11 14 - 0.14 From Table 1 it can be seen that the incorporation of FCP within the range of 0.5 to 3.0% by weight based on the weight of starch has resulted in a dramatic fall in a viscosity of the emulsion, particularly after the emulsion had been stored for a period of a week, which is a strong indication of the final viscosity of the emulsion and is significant,.because in general aqueous emulsions are stored for a period of up to several months before they are actually employed.

Example 2.

In this Example, the emulsions A to E prepared in Example 1 were used to size a sulphite bleached BERGVIC paper pulp in a Mavis British Standard pulp evaluation apparatus (sold by H. E. Messmer in London), by the following general method. Two litres of pulp having consistency of 0.6% and a pH of about 8 were disintegrated for 1800 revolutions, the aqueous emulsion added and the pulp disintegrated for a further 1800 revolutions.

Where a further retention aid was used, in this Example 0.3% by weight based on the emulsion of a 10% by weight solution of an epi- chlorohydrin modified polyamide sold by Hercules Powder Co., Delaware, under the Trade Name KYMENE 557 (KYMENE is a registered Trade Mark), it was added to the disintegrator 250 revolutions after the addition of the aqueous emulsion. After the period of disintegration, i.e. after 3,600 revolutions, aliquots of 200 mls; of the pulp were transferred to the hand sheet machine in which the water had previously been adjusted to pH 8. Sheets of paper were then prepared using the standard procedure and dried and cured by heating on a rotary drum drier for 1.5 minutes at a temperature of llO"C. The sheets were then conditioned under the standard conditions of 20 C and 65% RH for 9 hour. The ability of the sheets to resist penetration by water was measured using a standard Cobb Test. In the Cobb Test the sheets were contacted with water for a period of 1 minute and the result ex pressed in terms of the grammes of water absorbed per square metre of paper; the lower is the value in the Cobb Test, the better and more effective has been the sizing.

TABLE 2

Value in Cobb Test on adding % by wt. of cyclic imide + Retention aid Emulsion 0.675 0.1 0 D5 0.075 A 20 21 34- 23 B 31 23 35 29 C 32 27 33 25 D 36 24 37 30 33 24 38 27 From Table 2, it can be seen that the aqueous emulsions containing from 0.5 % to 3.0% by weight of FCP demonstrated only slightly worse sizing than the comparable emulsion which contained no FCP.

WHAT WE CLAIM IS:- 1. A composition for treating cellulosic materials comprising an aqueous emulsion of a cyclic imide N- substituted by a hydrophobic acyl radical as herein defined, and a cationic starch, the emulsion containing from 0.5 to 3.0% by weight of a formaldehyde condensation product of sodium naphthalene sulphonate, based on the weight of the starch.

2. A composition as claimed in claim 1 wherein the emulsion contains from 1.0 to 2.0% by weight of the formaldehyde condensation product of sodium naphthalene sulphonate based on the weight of the starch.

3. A composition as claimed in claim 1 or 2 wherein the weight of cationic starch to Nsubstituted cyclic imide is not more than 1:1 and not less than 2:5.

4. A composition as claimed in claim 3 wherein the weight ratio of cationic starch to N-substituted cyclic imide is from 2:3 to 2:5.

5. A composition as claimed in claim 4 containing from 5 to 7.5% by weight N-substi tuted cyclic imide and from 2 to 5 % by weight cationic starch.

6. A composition as claimed in claim 5 containing from 5.5 to 6.5% by weight N-substituted cyclic imide and from 2.5 to 4.0% by weight cationic starch.

7. A composition as claimed in any preceding claim wherein the cyclic imide is an N-acyl derivative of succinimide, cyclohexane-1,2-dicarboximide, 4-cyclohexene-1,2-dicarboximide or 3,6 - endoxo - 4 - cyclohexene - 1,2 - dicarboximide.

8. A composition as claimed in any preceding claim wherein the hydrophobic moiety of the N-acyl radical has a chain length of 15 to 21 aliphatic carbon atoms.

9. A composition as claimed in claim 8 wherein the N-acyl radical is a stearoyl radical.

10. A composition as claimed in any pre

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Where a further retention aid was used, in this Example 0.3% by weight based on the emulsion of a 10% by weight solution of an epi- chlorohydrin modified polyamide sold by Hercules Powder Co., Delaware, under the Trade Name KYMENE 557 (KYMENE is a registered Trade Mark), it was added to the disintegrator 250 revolutions after the addition of the aqueous emulsion. After the period of disintegration, i.e. after 3,600 revolutions, aliquots of 200 mls; of the pulp were transferred to the hand sheet machine in which the water had previously been adjusted to pH 8. Sheets of paper were then prepared using the standard procedure and dried and cured by heating on a rotary drum drier for 1.5 minutes at a temperature of llO"C. The sheets were then conditioned under the standard conditions of 20 C and 65% RH for 9 hour. The ability of the sheets to resist penetration by water was measured using a standard Cobb Test. In the Cobb Test the sheets were contacted with water for a period of 1 minute and the result ex pressed in terms of the grammes of water absorbed per square metre of paper; the lower is the value in the Cobb Test, the better and more effective has been the sizing. TABLE 2 Value in Cobb Test on adding % by wt. of cyclic imide + Retention aid Emulsion 0.675 0.1 0 D5 0.075 A 20 21 34- 23 B 31 23 35 29 C 32 27 33 25 D 36 24 37 30 33 24 38 27 From Table 2, it can be seen that the aqueous emulsions containing from 0.5 % to 3.0% by weight of FCP demonstrated only slightly worse sizing than the comparable emulsion which contained no FCP. WHAT WE CLAIM IS:-

1. A composition for treating cellulosic materials comprising an aqueous emulsion of a cyclic imide N- substituted by a hydrophobic acyl radical as herein defined, and a cationic starch, the emulsion containing from 0.5 to 3.0% by weight of a formaldehyde condensation product of sodium naphthalene sulphonate, based on the weight of the starch.

10. A composition as claimed in any pre

ceding claim containing additionally a polyacrylamide retention aid.

11. A composition as claimed in claim 10 wherein the polyacrylamide retention aid is present in an amount of from 0.03% to 0.2% by weight based on the emulsion.

12. A composition suitable for treing cellulosic materials substantially as described herein with respect to any of emulsions B to E in Example 1.

13. A process for treating cellulosic materials comprising the step of contacting the cellulosic material with a sizing or waterproofing amount of a composition as described in any preceding claim at a temperature sufficiently high for reaction to occur between the cyclic imide and the cellulosic material.

14. A process for treating cellulosic materials substantially as described herein with respect to the use of any one of Emulsions A to E in Example 2.