GB2268941A

GB2268941A - Rosin sizes

Info

Publication number: GB2268941A
Application number: GB9215835A
Authority: GB
Inventors: Michael James Jaycock; Darren Keith Swales
Original assignee: Roe Lee Paper Chemicals Co Ltd
Current assignee: Ciba Specialty Chemicals RC GB Ltd
Priority date: 1992-07-24
Filing date: 1992-07-24
Publication date: 1994-01-26
Also published as: GB9215835D0

Abstract

Rosin is blended with at least one other component to produce a mixture with a lower melting point than the original rosin. The mixture may then be used for producing a rosin size emulsion using methodology conventionally employed in the production of AKD emulsion. The other component may be a fatty acid, amine, ester or alcohol or a rosin ester.

Description

ROSIN SIZES The present invention relates to rosin sizes which are used extensively in the sizing of paper and other fibrous materials (usually of cellulosic origin).

It is an object of the present invention to obviate or mitigate the disadvantages associated with the production of conventional rosin sizes.

According to a first aspect of the present invention there is provided a method of producing a rosin emulsion comprising blending a rosin with at least one other component to the extent that the melting point of the mixture is below the melting point of the rosin, and preparing an emulsion of said mixture in water.

According to a second aspect of the present invention there is provided a mixture of a rosin and at least one other component such that the mixture has a melting point below that of the rosin.

The term rosin as used herein is also intended to include modified rosin, e.g. "paratreated" rosin (i.e. rosin treated with paraformaldehyde), fortified rosin (e.g. fortified by reaction with fumaric or maleic acid or anhydride), and esterified rosin.

Generally the rosin and the additional component(s) are blended together in the molten state. By varying the amount and/or chemical composition of the additional component(s), it is possible to produce a mixture having a melting point at any level between the melting point of the rosin (or modified rosin) and ambient temperature or even below.

Significant advantages are obtained by reducing the melting point of the rosin. For example, the melting point reduction may be such as to produce the mixture (i.e. blend of rosin plus other component) may be converted to an emulsion using methodology other than the Bewoidprocess as conventionally used for producing rosin size emulsion. The Bewoid process starts with a fortified rosin usually having a melting point of 90-100 C. The process involves melting the rosin and treating the melt with water and caustic soda prior to addition of a casein solution to produce the final emulsion of rosin in water. The melting point of the rosin necessitates the use of temperatures over 1000 C during the initial emulsifying stage.This is a significant disadvantage of the Bewoid process which is reflected in the fact that the process is generally operated to produce a maximum of about 2 tons per batch.

However by producing the rosin mixture as aforesaid, the melting point of the mixture may be at a level such that apparatus as used for producing emulsions of Alkyl Ketene Dimer (AKD) which are of significantly lower melting point than fortified rosins. Such apparatus comprises a melter; a stirred reactor vessel containing water to which chemicals and stabilisers are added before the addition of molten AKD wax; and homogeniser to form the small particle size emulsion from the contents of the reactor. Using the AKD methodology, a rosin size emulsion may be prepared (using the rosin mixture of the invention) by melting the mixture and then dispersing and stabilising the rosin with a an anionic, cationic, zwitterionic, or non-ionic dispersant which performs both functions, e.g. sodium lignin sulphonate.Alternatively, the rosin mixture may be melted, dispersed with an anionic, cationic, a zwitterionic or non-ionic dispersant and then stabilised with a separate stabiliser. For this latter alternative, it is preferred that the dispersant is anionic and that the stabiliser is cationic and used in excess.

Usually the plant for forming an AKD emulsion will produce batches of up to about 10 tons. Therefore it is possible (using apparatus of the type -used for production of AKD emulsion) to produce batches of rosin size emulsions larger than those conventionally obtained using the Bewoid process. There is the further significant advantage that the same apparatus may, of course, be used for the production of rosin emulsions and AKD emulsions.

The homogenization route (as used for forming AKD emulsions) is the preferred method of forming the present rosin size emulsions as it permits cationic rosin emulsions to be prepared easily using a small amount of anionic dispersant, either cationic starch or starch derivatives, or synthetic cationic polymers, or mixtures of the two.

In some cases however the traditional Bewoid apparatus can also be used for producing the rosin size dispersions of the present invention.

In order to produce a rosin mixture which can be converted to an emulsion by the AKD methodology, it may be necessary to reduce the m.p. of the original rosin from 80-110 C (a typical melting point range) to 50-70 C. However the invention also provides benefits with much lower melting point reductions. In particular a melting point reduction of only a few OC may be beneficial when an MG cylinder (in the U.S.A. a Yankee Dryer cylinder) is used in that adhesion of the paper sheet to the paper cylinder can be more easily controlled.

Moreover the lower melting point allows sizing to develop more quickly.

If the melting point of the rosin is reduced by only 1-20 then it may be necessary to use the Bewoid process for production of the rosin size emulsion.

Many materials can be used to lower the m.p. of the rosin.

Particularly preferred are organic materials such as:a. fatty acids or other organic acids, e.g. octadecanoic acid; b. fatty amines or other organic amines, e.g. octadecylamine; c. fatty or other organic esters of glycerol or polyethylene glycol or ethylene glycol; d. rosin esters of glycerol or polyethylene glycol or ethylene glycol; e. simple fatty acid or other organic acid esters such as ethyl octadecanoate, methyl hexadecanoate, etc.; f. simple rosin esters such as ethyl rosinate, methyl rosinate, etc.; g. esters of petroleum derived acids, such as petroleum sulphonates and naphthalene sulphonates; h. fatty or other organic alcohols, e.g. octadecanol, and i. mixtures of the above.

In the above list, the materials qualified by "organic" mean organic substances with the functional group specified and with properties such that after melting, mixing and/or reacting with the rosin the substance has limited solubility in the aqueous phase but is soluble in the organic phase.

The acids, alcohols, and amines mentioned in the above list may for example have a straight or branched chain containing 8-25 carbon atoms.

It should be understood that it is possible to use as the other component a material which is similar to the rosin (e.g. another rosin material) provided of course that the melting point depression is achieved. Thus for example if the rosin (whose melting point is to be modified) is a rosin ester then it is possible to use a different rosin ester to achieve the melting point reduction.

A particularly preferred material which may be used for lowering the melting point of the rosin is Tall Oil Fatty Acid.

Typically the amount of material added to the rosin to reduce the melting point will be in the range 0.5 to 49% by weight of the mixture of the rosin and the other component.

Some of the above materials produce mixtures that can only conveniently be used in production processes that follow AKD type emulsion technology. For example it is difficult to make satisfactory emulsions from a mixture 30% stearic acid and 70% tall oil rosin by the Bewoid patent route because of difficulties in controlling the amount of soap produced during the caustic addition stage.

Any of the mixtures that produce a significant lowering of the m.p. can be made by AKD emulsion technology. The precise temperature needed is such that a liquid rosin phase can be conveniently maintained at all stages of the production process (mixing and homogenizing, etc.) prior to the final crash cooling.

The rosin used in the method of the invention may for example be gum rosin, tall oil rosin, or wood rosin (i.e. any rosin derived from wood as the original source). If desired, the rosin may be treated with paraformaldehyde, and/or fortified with maleic or fumaric acids, and/or esterified (i.e. with any or all of the usual ways of treating the rosin in current manufacturing procedures).

The invention is illustrated by the following non-limiting example.

Example 1.

A mixture was prepared of 49% tall oil fatty acid (TOFA) with 51% Chinese gum rosin (CGR) by warming in a heated vessel and stirring.

When mixing had produced a homogeneous melt, the mixture was cooled and was still a liquid at room temperature.

700 ml of water was placed in the homogenizer and heated to about 400C. 35 g of Basyntan M (from BASF) was dissolved in the water and then 274 g of the mixture of CGR/TOFA added. The total mixture was homogenized for 25 min at 4000 psi. The resulting emulsion had mean volume % particle size of 0.285 pm as determined using a Coulter/LS130 particle size analyzer.

The sizing efficiency of this CGR/TOFA emulsion can be gauged by the comparison with Neusize 3 (a Roe Lee Paper Chemicals Co. Ltd.

fortified rosin emulsion size), both emulsions added to a bleached kraft stock using the Neusize technique.

Neusize CGR/TOFA % size 0.65 0.60 0.57 0.58 % alum 2.60 2.40 2.28 2.32 Cobb value/g m~2 15.2 16.6 17.1 16.7 % size = wt. emulsion solids added x 100 / sheet wt.

gÓ alum = wt. Al2(SO4)3.18H2O added x 100 / sheet wt.

The emulsion was stable for more than 3 months.

Claims

1. A method of producing a rosin emulsion comprising blending a rosin with at least one other component to the extent that the melting point of the mixture is below the melting point of the rosin, and preparing an emulsion of said mixture in water.

2. A method as claimed in claim 1, wherein the other component is a fatty acid or other acid, e.g. octadecanoic acid.

3. A method as claimed in claim 1, wherein the other component is a fatty amine or other amine, e.g. octadecylamine.

4. A method as claimed in claim 1, wherein the other component is a fatty acid ester or other acid ester of glycerol or polyethylene glycol or ethylene glycol.

5. A method as claimed in claim 1, wherein the other component is a rosin ester of glycerol or polyethylene glycol or ethylene glycol.

6. A method as claimed in claim 1 wherein the other component is a simple fatty acid or other acid ester such as ethyl octadecanoate, methyl hexadecanoate, etc.

7. A method as claimed in claim 1, wherein the other component is a simple rosin ester such as ethyl rosinate, methyl rosinate, etc.

8. A method as claimed in claim 1, wherein the other component is a fatty alcohol or other alcohol, e.g. octadecanol.

9. A method as claimed in claim 1, wherein the other component is an ester of a petroleum derived acid.

10. A method as claimed in any one of claims 1 to 9 wherein the melting point of said mixture is above ambient temperature, and said mixture is melted.

11. A method as claimed in any one of claims 1 to 10 wherein the emulsion is formed by homogenisation.

12. A method as claimed in claim 11 wherein the rosin is dispersed and stabilised by a single agent performing both functions.

13. A method as claimed in claim 11 wherein the rosin is dispersed by an anionic, cationic or non-ionic dispersant, and stabilised with a separate stabiliser.

14. A mixture of a rosin and at least one other component such that the mixture has a melting point below that of the rosin.

15. A mixture as claimed in claim 14 wherein said other component is as specified in any one of claims 2 to 9.