Use of alkylamine salts as viscosity regulating substance

Abstract

 The present invention relates to novel compounds in the form of alkyl amine acid addition salts, which compounds have the ability to regulate the viscosity of coating mixes when mixing together mixes of mutually different basic compositions. The invention also relates to the use of such alkyl amine acid addition salts for controlling the viscosity of a combined mixture of such coating mixes.

Description

Technical Field

[0001] The present invention relates to novel viscosity regulating substances for regulating the viscosity of paper coating mixes, and to the use of such substances.

[0002] The object of the present invention is to enable the interchange of coating mixes in continuous paper coating processes without substantial change in the viscosity of said mixes at the transition from one mix to the other and/or the mixing of the mixes one with the other.

Background of the Invention

[0003] Paper is coated by applying an extremely thin layer of coating mix to a paper web. The purpose of the coating is to improve the properties of the paper, particularly with regard to uniformity of surface, and its ability to accept inks, laquers etc from the printing press. Such mixes today comprise finely ground kaolin, dispersant, and water, or chalk, dispersant, water. Mixes have also been proposed, and prepared, that comprise calcium sulphate dihydrate (gypsum) dispersant and water. Such mixes have also been found usable for the aforesaid purpose. It has also been found, however, that when switching from a gypsum mix to a kaolin mix the viscosity of the combined mixes is much higher than that of a single mix, which renders the system inoperable.

[0004] Due to the complexity of paper machines it is not convenient to stop production in order to clean the coating equipment. It is also necessary, however, to be able to switch from one type of mix to another without stopping production, in order to satisfy demands for paper with different coatings.

[0005] Various systems have been tested, inter alia with variation of the dispersant, although without success.

Summary of the Invention

[0006] It has now surprisingly been found possible to solve this problem in a simple and efficient manner by means of the present invention, which to this end proposes the use of compounds which comprise an acid addition salt of an alkyl amine having 1-5 carbon atoms in the alkyl chain, preferably 2-4 carbon atoms, and still more preferably 3-4 carbon atoms.

[0007] Part of the alkyl amine is present as an acid addition salt. The acid addition salt is prepared by reaction with sulphuric acid, phosphoric acid, halogen hydrochloric acid, nitric acid, perchloric acid, aliphatic, alicyclic, aromatic and heterocyclic carbonic and sulphonic acids. In this regard, such salts are hydrochlorides, sulphate, hydrogen sulphate, phosphate, hydrogen phosphate, nitrate, formiate, acetate, propionate, succinate, glycolate, gluconate, heptonate, lactate, tartrate, citrate, oxalate, ascorbate, maleate, hydroxy maleate, bensoate, p-amino bensoate, p-hydroxy bensoate, salicylate, p-amino salicylate, picrate, diethylene triamine pentaacetate (DTPA), ethylene diamine tetraacetate (EDTA), nitrilo triacetate (NTA), hydroxy ethyl imino diacetate, bis (hydroxyethyl) gluconate.

[0008] Further characteristics are set forth in the following claims.

[0009] The alkyl amines used in the group preferably comprise primary alkyl amines, such as methylamine, ethylamine, propylamine, 1-methyl ethyl amine, butyl amine, 1-methyl propyl amine, 2-methyl propyl amine, pentyl amine, 3-methyl butyl amine, 2-methyl butyl amine, 1-ethyl propyl amine, 1-methyl butyl amine, 1,1-dimethyl ethyl amine, 1,1-dimethyl propyl amine, although they may also comprise secondary, tertiary, and quarternary alkyl amines, such as dimethyl amine, diethyl amine, trimethyl amine, tetramethyl amine.

[0010] The product is prepared by mixing a solution of an alkyl amine with a solution of acid which will react to form the intended acid addition salt. It is irrelevant in this respect whether one solution is added to the other, or vice versa.

[0011] The respective solutions may have the form of a concentrate or a solvent solution of the compound concerned.

[0012] The ratio of amine to acid is from 1 to 4, depending upon the degree of substitution desired.

[0013] In the process of adding one solution to the other, care is taken to ensure that the alkyl amine does not boil, by suitable control of temperature.

[0014] The reaction between alkyl amine and acid takes place instantaneously, whereafter the product can be filtered off (when the reaction takes place in a non-dissolving solvent) or can be used direct, in solution.

Example 1

[0015] 33.6 kg of citric monohydrate were dissolved in 30 1 of water. 36 1 (25.9 kg) of n-propylamine were then added carefully to the solution, while stirring and cooling the system. The temperature was maintained beneath 45°C. The resultant product, (n-propylamine)3-citrate remained in solution in the water phase.

[0016] The follwoing systems were prepared in a similar manner:

A series of experiments was conducted on the basis of the above substances, in which there was prepared a first kaolin mix comprising 100 parts of dry kaolin, 50 parts of water, 0.35 parts of 100%-Dispex®, and NaOH. The pH of the mix was 8.5. A suspension was then prepared over a period of one hour, by adding to the mix 9 parts of latex DOW 685, 1.2 parts of CMC (carboxy methyl cellulose) and water to a viscosity of about 1000-1500. The pH of the suspension was adjusted to 8.5, to obtain a viscosity of about 1500 cps, dry solids content 55-58%. Peripheral data concerning different starting kaolin mixes is given in Table 1 below, left column.

[0017] A further gypsum based mix was prepared from 100 parts dry gypsum, 1.5 parts CMC, 9 parts latex DOW 685, NaOH to pH 8.5, and water, there being obtained a mix with DS 64.4%, viscosity 950 cps. Various amines according to the aforegoing were added to 400 g of the kaolin mix thus prepared, in the quantities set forth in Table 1, whereafter 30.1 g of the gypsum mix were added and the viscosity of the resultant mixture was measured. The viscosity was also measured after adding the amine. The results obtained when adding the gypsum based mix are set forth in the right column of Table 1 below.

[0018] The present invention has also been tested on a semi-industrial scale in apparatus having a volume of 25 litres. The apparatus comprised a machine tank having a volumetric filling capacity of 15 litres, a filter, and a buffer tank provided with an outlet leading to the machine tank and to the "coating station", i.e. the apparatus simulated the coating of a paper web by taking out 1 litre of mix per minute. The volume circulated was 7 litres and the flow rate 10 litres per minute. The system was filled with a mix 1, whereafter the mix was pumped around the system and "coating commenced". Subsequent to emptying the machine tank, by consecutive simulated "coating" procedures, such that about 10 litres of mix 1 remained, the system was re-filled with mix 2, this mix being intended to replace mix 1 without interrupting circulation and while continuing the "coating" process. Samples were taken from the combined mixture of mixes 1 and 2 at 30 second intervals, in order to determined the viscosity, pH, and in some cases also DS and the ratio of mix 1 to mix 2 in the combined coating mixture.

[0019] The results set forth in Table 2 were obtained when testing a conventional kaolin coating mix (mix 2), 100 parts of kaolin, 0.35 parts Dispe#N40, 1.2 parts of CMC FF5, and 9 parts of latex DOW 685, DS 56-59%, pH 8.5-9, and a gypsum--based coating mix (mix 1) comprising 100 parts of dry gypsum, dihydrate, 1.5 parts CMC, and 9 parts of DOW 685, DS 60-65%, pH 8.5-9, without further addition of a compound according to the present invention.

[0020] Table 3 below discloses the results obtained when adding to mix 1 (the gypsum mix) 0.4 parts of propyl amine phosphate, calculated as amine.

[0021] In a further test, mix 1 and mix 2 were mixed together in different proportions, while carefully stirring the system for one minute. The viscosity of the combined mixture was determined in accordance with the Brookfield technique (30 s 100 rpm). In this test, a study was made of a mixture between a gypsum-based mix according to the above (mix 1) and a kaolin mix (mix 2) with a synthetic thickener, DS 55% and viscosity mPas. The results are given in Tables 4 and 5 below.

[0022] It is evident from the above that the viscosity of the coating mixture is stabilized very effectively when an alkyl amine acid addition salt according to the aforesaid is used.

[0023] It has been found that when using the alkyl amine acid addition salt, an acceptable result is achieved even when only a part of the alkyl amine exists in the form of such an acid addition salt.

[0024] A satisfactory result can also be obtained by adding each of the salt components, i.e. alkyl amine and acid, separately to the coating mix.

[0025] By kaolin-based mix is meant here, and in the aforegoing, a mix in which the pigment fraction contains more than 50% kaolin. Kaolin mixes that contain 60% kaolin and 40% gypsum are thus known in the art.

[0026] By chalk-based mixes is meant a mix that contains more than 50% chalk, while by gypsum-based mixes is meant a mix that contains more than 50% gypsum. Thus, the pigment fraction need not be totally based on one pigment.

Claims

1. A compound for regulating the viscosity of coating mixes, characterized in that said coating consists of an acid addition salt of an alkyl amine having 1-5 C in the alkyl chain, the acid addition salt not being an oxalate; and in that when the acid addition salt is acetate, the alkyl amine is not methyl amine, and when the acid addition salt is a sulphate or hydrogen sulphate the alkyl amine is not a quarternary alkyl amine.

2. A compound according to claim 1, characterized in that the acid addition salt is obtained by reaction with an acid from the group sulphuric acid, phosphoric acid, halogen hydrochloric acids, nitric acid, perchloric acid, aliphatic, alicyclic, aromatic and heterocyclic carbonic and sulphonic acids.

3. A compound according to claim 2, characterized in that the acid addition salt is either hydrochloride, hydrogen sulphate, hydrogen phosphate, sulphate, phosphate, or nitrate.

4. A compound according to claim 2, characterized in that the acid addition salt is either formiate, acetate, propionate, succinate, glycolate, heptonate, lactate, tartrate, citrate, oxalate, ascorbate, maleate, hydroxy maleate, bensoate, p-aminobensoate, p-hydroxy bensoate, salicylate, p-aminosalicylate, picrate, diethylene triaminopentaacetate, ethyl diaminetetraacetate, nitrilo triacetate, hydroxy ethyliminodiacetate or bi(hydroxyethyl)gluconate.

5. A compound according to claim 1, characterized in that the alkyl amine is a primary alkyl amine.

6. A compound according to claim 1, characterized in that the alkyl amine is a secondary alkyl amine.

7. A compound according to claim 1, characterized in that the alkyl amine is a tertiary alkyl amine with 1-3 C in the alkyl groups.

8. A compound according to claim 1, characterized in that the alkyl amine is a quarternary alkyl amine with 1-2 C in the alkyl groups.

9. The use of an acid addition salt of an alkyl amine with 1-5 C in the alkyl chain for regulating the viscosity of coating mixes when blending together different kinds of such mixes.

10. The use according to claim 9, in which the compound is added in an amount corresponding to 0.05-2% by weight of the weight of the ingoing prepared coating mixture.

11. The use according to claim 9, in which the coating mixes consist respectively of a kaolin-based and a calcium sulphate-based coating mix.

12. The use according to claim 9, in which the coating mixes consist respectively of a chalk-based and a calcium sulphate-based coating mix.

13. The use according to claim 9, in which the coating mixes consist respectively of a kaolin-based and a chalk-based coating mix.