GB1569591A

GB1569591A - Paper sizing agents

Info

Publication number: GB1569591A
Application number: GB1434576A
Authority: GB
Original assignee: Tenneco Chemicals Inc
Current assignee: Tenneco Chemicals Inc
Priority date: 1977-04-06
Filing date: 1977-04-06
Publication date: 1980-06-18

Description

(54) IMPROVEMENTS IN OR RELATING TO PAPER SIZING AGENTS (71) We, TENNECO CHEMICALS, INC., of Park 80 Plaza West-1, Saddle Brook, New Jersey 07662, United States of America, a corporation organised and existing under the laws of the State of Delaware. United States of America, 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: This invention relates to paper sizing agents and is concerned in particular with reactive sizes for cellulosic fibres. A 'reactive sizing agent is one which, in use, forms with cellulose a chemical bond, as opposed to the electrostatic type of bond formed by conventional sizes.

There are two main kinds of reactive sizing agent commerically available at the present time. One type is that based upon alkyl ketene dimers, such as the product marketed as "Aquapel" (Regd. Trademark) by Hercules Inc, and the other type is that based upon succinic anhydrides, such as the product marketed as "Fibran" (Regd. Trademark) by Laing International.

Alkyl ketene dimers develop full sizing on cellulosic fibre only under the influence of prolonged heat. Substituted succinic anhydrides, although they develop full sizing under mild drying conditions, are rendered ineffective by hydrolysis in the aqueous media from which they are applied. This necessitates the use of costly and inconvenient emulsification equipment on the paper machine. The product supplied, when a substituted succinic anhydride is specified, typically consists of two liquids and a solid, which have to be mixed in specially effective emulsifying equipment as required, because the reactivity initially exhibited by the emulsified product is rapidly lost through hydrolytic action. Such sizing agents are usually substantially ineffective after 2 hours and in practice it is advisable to conduct the paper manufacture so that each batch of sizing emulsion is used within 1/2 hour of its preparation.

The present invention avoids or at least minimises the defects of known reactive paper sizing agents and comprises a sizing agent in the form of a stable emulsion having a continuous phase comprising water and an emulsifier and a disperse phase comprising a solution in an organic solvent of a reaction product of an anhydride of an a,ss-unsaturated carboxylic acid with one or more organic compounds having at least two olefinic double bonds per molecule. It has been discovered that reaction products of this description can be formulated as stable emulsions, where the continuous phase is an aqueous medium and yet the droplets or particles representing the discontinuous phase of the emulsion, i.e. the sizing agent reaction product per se, retain their reactivity despite the fact that this is largely attributable to their hydrophobic properties. It is suggested that this valuable property, which contributes to the stability of the emulsion and therefore gives it an extended shelf life, may be due to the reaction product forming an emulsion of solid particles rather than liquid droplets, like the usual oil-in-water emulsions. The solid state of the reaction product would confer greater protection against hydrolysis by the aqueous medium forming the continuous emulsion phase. It is to be noted, however, that the products of the invention may include reaction products which are liquid under normal conditions and that the solid state theory may not be a complete explanation for the desirable combination of stability with reactivity which is demonstrated by the products according to the invention.

According to one preferred feature of this invention, the reaction product is made using maleic anhydride as one of the reactants.

According to another preferred feature of the invention, the reaction product is made by reacting maleic anhydride (or any other suitable anhydride such as citraconic anhydride or itaconic anhydride, alone or in admixture with maleic anhydride) with liquid hydrocarbon resins having many properties similar to those usually exhibited by natural resins, These include, in particular, the presence of the diene and/or cyclodiene structure in the molecule(s) of the hydrocarbon resin, enabling adduction or addition to take place during the reaction step. One commerically available liquid hydrocarbon resin product which is especially suitable for use in carrying out the invention is that marketed under the name "Escopol"" (Regd. Trademark), having a molecular weight of about 300 and a complex monomer composition including cyclodienes, methyl-cyclodienes, C4-unsaturates, C5- unsaturates and styrene. Typical properties of this material include: iodine number 190, bromine number 77, non-volatiles 85% by weight, specific gravity 1.01 at 150C, viscosity 25 centistokes at 100"C, acid number 0.1, saponification number 1, and flash point (Cleveland open cup) 121"C.

Another class of reactants which can be maleated, i.e. reacted with maleic anhydride, or otherwise reacted to make a storage-stable emulsifiable reaction product are dienecontaining fatty acids having at least C14 and a molecular weight of at least 195.

Furthermore, mixtures of such acids and "Escopol" or other liquid hydrocarbon resins can be employed.

The invention in its currently preferred form is exemplified by the reaction product of "Escopol" polydrying oil and maleic anhydride and is so described herebelow. In general, a reaction temperature of 1200-2500C is necessary at a pressure in the range from 1 to 5 atmospheres, in order to achieve the maleation reaction satisfactorily and in a suitable time.

It has been found that the addition products with maleic anhydride function well as reactive sizes over wide ranges of the "Escopol" polydrying oil to maleic anhydride molar ratio. Preferably, this ratio is from 1:0.1 to 1:1.5, most preferably from 1:0.5 to 1:1.

The resinous products can be applied to paper from emulsions of solutions of aromatic hydrocarbon solvents, and also chlorinated aliphatic hydrocarbons, in cationic starch solution. Emulsification is desirably carried out with molar ratios of resin to cationic starch of 1:0.5 to 1:5, the optimum range being from 1:1 to 1:2. Other emusifiers can be used in place of, or in conjunction with, cationic starch if desired; but cationic starch is preferred.

It is found that. in contrast to the commercially-available reactive sizes which are liquids, the reaction products of this invention are typically glass-like resinous solids, i.e. they appear to be solids, but in fact are supercooled liquids like glass, pitch and resin itself.

These reaction products dissolve in a wide range of organic solvents, but for preparation of the emulsion, the preferred solvent is toluene.

In order that the invention may be readily understood, a number of examples of preferred embodiments thereof are described, by way of illustration, wherein "Escopol" and "Fibran" are Regd. Trademarks.

Example 1 A 1:0.6 molar addition product was prepared by reacting "Escopol" polydrying oil with maleic anhydride. This reaction was carried out by heating together 191 gm of the oil and 38.3 grams of the anhydride at 205"C in a small stainless steel bomb pressurised to 2 atmospheres with nitrogen. These conditions were maintained for 3 hours. The product was a resinous material having an acid number of 156 and a softening point of 63"C. (ring and ball method, ASTM D36). Free maleic anhydride in the product was determined volumetrically to be 0.18%. A paper sizing agent was prepared by making an emulsion of 10 gm of the resin dissolved in 4 grams of toluene and emulsified in 486 grams of 3.1% "Cato 8" (Regd. Trademark) a cationic starch marketed by Laing National Starch) solution at 20"C on an Ormerod QP Blue Calf Homogeniser. Thus an emulsion with a resin to cationic starch ratio of 1:1.5 was obtained at 5% total solids.

Unsized paper sheets produced from a 1:1 mixture of bleached kraft and bleached hardwood pulp were used to test sizing.

The maleated "Escopol" resin was employed in the form of dilutions of the aforementioned emulsion, by immersing the unsized paper sheets for 2 seconds in a shallow trough containing the diluted emsulsion. Excess diluted emulsion was removed by pressing between two sheets of blotting paper and the sized sheets were dried in a "Kodak" (Regd.

Trademark) photographic print drier. Basic drying conditions were set such that sheets were in contact with the drier roll at 100"C for 2 minutes. In addition, some sheets were given a further oven drying period at 120 C.

The reactive nature of the paper sizing agent of the invention was demonstrated by acetone extraction of the sized sheets in a Soxhlet extractor for 24 hours. Acetone is a good solvent for the subject resins.

The sizing efficiency was determined by the Cobb Size Test, according to T.A.P.P.I.

procedure T.441. A penetration time of 45 seconds was used.

Results, which was an average for 4 sheets, are given below, in Table 1. For comparison, results obtained with a commerically-available substituted succinic anhydride size, "Fibran" (Laing National Starch) are included in Table 2.

TABLE 1 Cobb Values gm.m Parts resin/100 2 minutes dry 2 minutes dry at 2 minutes dry at parts dry fibre at 100"C 1000C + 30 100"C Acetone minutes at 1200C Extract Air Dry 0.48 17 17 16 0.27 19 19 16 0.12 25 27 28 TABLE 2 Cobb Values gm.m Parts Fibran/100 2 minutes dry 2 minutes dry at 2 minutes dry at parts dry fibre at 100"C 100"C + 30 100"C Acetone minutes at 1200C Extract Air Dry 0.53 22 23 18 0.27 23 23 24 0.13 25 25 26 These results show that the paper sizing agent of the invention is as good as, and usually is better than, the commercially-available product.

Example 2 A 1:0.8 molar addition product was prepared from "Escopol" polydrying oil and maleic anhydride, namely a product having a higher proportion of the anhydride than that of Example 1.

1500 gm of the oil was heated to 200"C with agitation beneath a nitrogen blanket. Maleic anhydride (400 grams) was then added in 100 gm aliquots, allowing 30 minutes for reaction between each addition. The product obtained was a resinous material with an acid number of 213 and a ring and ball softening point of 70"C. Free maleic anhydride was determined volumetrically to be 0.9%. A paper sizing agent was made from 10 gm of this resin dissolved in 6 grams of toluene and emulsified in 484 grams of 4.1% Cato 8 solution as in Example 1.

Thus an emulsion of 6% total solids with a resin to cationic starch ratio of 1:2 was obtained.

Sizing efficiency was tested as previously described. Results are given in Table 3.

TABLE 3 Cobb Value gm.m2 Parts resin/100 2 minutes dry 2 minutes dry at 2 minutes dry at parts dry fibre at 100"C 100"C + 30 100"C Acetone minutes at 1200C Extract Air Dry 0.5 17 16 15 0.25 17 15 17 0.12 20 17 18 This product gave results equal to or even better than those of Example 1, Table 1, even at the lower sizing level of 0.12 pph.

Example 3 A 1:0.4 molar addition product was prepared from "Escopol" polydrying oil and maleic anhydride. The oil (240 grams) and the anhydride (31.3 grams) was heated with agitation to 1500C beneath a nitrogen blanket. These conditions were maintained for 8 hours. The product was a soft resinous material of acid number 118. Free maleic anhydride was determined volumetrically to be 0.2%. A paper sizing agent was prepared by emulsifying 10 gm of the resin dissolved in 6 grams of toluene, in 484 grams of 4.1% Cato 8 solution in the aforementioned manner. Thus an emulsion of 6% total solids with a resin to cationic starch ratio of 1:2 was obtained.

Sizing efficiency with a 2 minute drying period at 1000C was determined as in Example 1.

TABLE 4 Parts Resin/100 parts dry fibre Cobb Value gm m 0.59 18 0.27 29 0.14 61 Example 4 A 1:1 molar addition product was prepared from "Escopol" polydrying oil and maleic anhydride. The oil (211 grams) and anhydride (67.5 grams) were heated together for 5 hours in a small stainless steel bomb pressurized to 3 atmospheres with nitrogen.

The product was a hard resinous material with an acid number of 232 and a ring and ball softening point of 82.5"C. Free maleic anhydride was determined volumetrically to be 1.1%. 10 grams of this resin were dissolved in 6 grams of toluene and emulsified in 484 grams of 4.1% Cato 8 solution as described in Example 1.

Sizing efficiency was determined for a 2 minute drying period at 100"C as previously outlined and the results obtained are given in Table 5.

TABLE 5 Parts Resin/100 parts dry fibre Cobb Calue gm m 0.52 16 0.26 29 0.14 Unsized Although the invention has been illustrated by means of examples of the use of the novel sizing agent for sizing pre-formed paper sheets, these are not to be considered as limitative.

It will be understood by those skilled in the art that the novel sizing agent can also be used, if desired, in the internal sizing of paper by mixing the sizing agent with an aqueous slurry of paper pulp. In other words, the sizing agent of this invention can be used in any of the known methods for sizing paper, including application at the size press or a coating apparatus.

It will also be understood that although it is preferred to use the sizing agent of this invention as the sole size, it can be used in conjunction with or admixture with conventional reactive sizes, or even with non-reactive size such as rosin size, if desired without departing from the scope of the invention. Further, the sizing agent can be used if desired with admixtures of cellulosic fibres and non-cellulosic fibres; and can be used together with conventional paper-making chemicals such as aluminum sulfate, polyamide polymers, cationic retention aids, wet-strength resins, starches, gums, and so on if it is desired to do so, even though such chemicals are not necessary in order to bond the sizing agent to cellulosic fibres.

WHAT WE CLAIM IS: 1. A paper sizing agent which is reactive with cellulosic fibres and which comprises a stable emulsion having a continuous phase comprising water and an emulsifier and a disperse phase comprising a solution in an organic solvent of a reaction product of an anhydride of an o:,t -unsaturated carboxylic acid with one or more organic compounds having at least two olefinic double bonds per molecule.

2. A paper sizing agent according to claim 1 wherein the emulsifier is cationic starch, the organic solvent is toluene, the a,P-unsaturated carboxylic acid anhydride is maleic anhydride, and the organic compound is a liquid olefinic hydrocarbon resin having an average molecular weight of about 300, an iodine number of about 190, a bromine number of about 77, a viscosity of about 25 centistokes at 100"C, and derived from a mixture comprising one or more cyclodienes, methyl cyclodienes, unsaturated compounds having 4

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Example 3 A 1:0.4 molar addition product was prepared from "Escopol" polydrying oil and maleic anhydride. The oil (240 grams) and the anhydride (31.3 grams) was heated with agitation to 1500C beneath a nitrogen blanket. These conditions were maintained for 8 hours. The product was a soft resinous material of acid number 118. Free maleic anhydride was determined volumetrically to be 0.2%. A paper sizing agent was prepared by emulsifying 10 gm of the resin dissolved in 6 grams of toluene, in 484 grams of 4.1% Cato 8 solution in the aforementioned manner. Thus an emulsion of 6% total solids with a resin to cationic starch ratio of 1:2 was obtained. Sizing efficiency with a 2 minute drying period at 1000C was determined as in Example 1. TABLE 4 Parts Resin/100 parts dry fibre Cobb Value gm m 0.59 18 0.27 29 0.14 61 Example 4 A 1:1 molar addition product was prepared from "Escopol" polydrying oil and maleic anhydride. The oil (211 grams) and anhydride (67.5 grams) were heated together for 5 hours in a small stainless steel bomb pressurized to 3 atmospheres with nitrogen. The product was a hard resinous material with an acid number of 232 and a ring and ball softening point of 82.5"C. Free maleic anhydride was determined volumetrically to be 1.1%. 10 grams of this resin were dissolved in 6 grams of toluene and emulsified in 484 grams of 4.1% Cato 8 solution as described in Example 1. Sizing efficiency was determined for a 2 minute drying period at 100"C as previously outlined and the results obtained are given in Table 5. TABLE 5 Parts Resin/100 parts dry fibre Cobb Calue gm m 0.52 16 0.26 29 0.14 Unsized Although the invention has been illustrated by means of examples of the use of the novel sizing agent for sizing pre-formed paper sheets, these are not to be considered as limitative. It will be understood by those skilled in the art that the novel sizing agent can also be used, if desired, in the internal sizing of paper by mixing the sizing agent with an aqueous slurry of paper pulp. In other words, the sizing agent of this invention can be used in any of the known methods for sizing paper, including application at the size press or a coating apparatus. It will also be understood that although it is preferred to use the sizing agent of this invention as the sole size, it can be used in conjunction with or admixture with conventional reactive sizes, or even with non-reactive size such as rosin size, if desired without departing from the scope of the invention. Further, the sizing agent can be used if desired with admixtures of cellulosic fibres and non-cellulosic fibres; and can be used together with conventional paper-making chemicals such as aluminum sulfate, polyamide polymers, cationic retention aids, wet-strength resins, starches, gums, and so on if it is desired to do so, even though such chemicals are not necessary in order to bond the sizing agent to cellulosic fibres. WHAT WE CLAIM IS:

1. A paper sizing agent which is reactive with cellulosic fibres and which comprises a stable emulsion having a continuous phase comprising water and an emulsifier and a disperse phase comprising a solution in an organic solvent of a reaction product of an anhydride of an o:,t -unsaturated carboxylic acid with one or more organic compounds having at least two olefinic double bonds per molecule.

carbon atoms, unsaturated compounds having 5 carbon atoms, and styrene.

3. A paper sizing agent according to claim 2 wherein the molar ratio of organic compound to maleic anhydride ranges from 1:0.1 to 1:1.5.

4. A paper sizing agent according to claim 3 wherein the molar ratio of organic compound to maleic anhydride ranges from 1:0.5 to 1:1.

5. A paper sizing agent according to claim 1 wherein the organic compound is a fatty acid containing two olefinic double bonds and at least 14 carbon atoms, and having a molecular weight of at least 195.

6. A paper sizing agent according to claim 1 substantially as herein described and with reference to Examples 1 to 4.

7. A method of making a paper sizing agent which is reactive with cellulosic fibres, comprising the steps of forming the reaction product of an anyhydride of an unsaturated carboxylic acid with one or more organic compounds having at least two olefinic double bonds per molecule, dissolving said reaction product in an organic solvent, and emulsifying the resulting organic solution in an aqueous solution of an emulsifying agent, whereby a stable emulsion containing said organic solution as the disperse phase is obtained.

8. A method according to claim 7 wherein the anhydride is maleic anhydride; the organic compound is a liquid olefinic hydrocarbon resin having an average molecular weight of about 300, an iodine number of about 190, a bromine number of about 77, a viscosity of about 25 centistokes at 100"C, and derived from a mixture comprising one or more cyclodienes, methyl cyclodienes, unsaturated compounds having 4 carbon atoms, unsaturated compounds having 5 carbon atoms, and styrene; the organic solvent is toluene; and the emulsifying agent is cationic starch.

9. A method according to claim 8 wherein the molar ratio of organic compound to maleic anhydride ranges from 1:0.1 to 1:1.5.

10. A method according to claim 9 wherein the molar ratio of organic compound to maleic anhydride ranges from 1:0.5 to 1:1.

11. A method according to claim 7 substantially as herein described and with reference to Examples 1 to 4.

12. A paper sizing agent, when made by a method according to any of claims 7 to 11.

13. A method of sizing paper which comprises saturating a paper sheet with a sizing agent according to any of claims 1 to 6 and 12 and drying the paper sheet at an elevated temperature.

14. Sized paper when made by a method according to claim 13.

15. Sized paper when made in accordance with any of Examples 1 to 4.