Aqueous glyoxyl-based insolubilizer composition for the surface treatment of paper and cardboard

Abstract

The invention relates to an aqueous insolubilizer composition intended for the surface treatment of paper and cardboard, comprising a mixture composed of glyoxal and of at least one alkali metal orthophosphate, and also its use.

Claims

1. A process for the surface treatment of paper or cardboard, comprising the step of contacting the paper or cardboard with an aqueous insolubilizer composition, wherein the aqueous insolubilizer composition comprises glyoxal and at least one alkali metal orthophosphate and wherein the pH of the aqueous insolubilizer composition is below 7.

2. The process according to claim 1, wherein said composition comprises, in aqueous solution, an alkali metal orthophosphate/glyoxal weight ratio between about 0.35 and 1.75.

3. The process according to claim 2, wherein said ratio is between about 0.5 and 1.2.

4. Paper or cardboard treated by the process of claim 3.

5. The process according to claim 2, wherein said ratio is between about 0.8 and 1.

6. The process according to claim 2, wherein the alkali metal orthophosphate comprises trisodium orthophosphate dodecahydrate.

7. Paper or cardboard treated by the process of claim 2.

8. The process according to claim 1, wherein the solids content of said composition is between about 20% and 60% by weight.

9. The process according to claim 1, wherein the solids content of said composition is between about 35% and 45% by weight.

10. The process according to claim 1, wherein the solids content of said composition is about 40% by weight.

11. The process according to claim 10, wherein the pH of said composition is adjusted to a value below 7 by addition of phosphoric acid.

12. The process according to claim 1, wherein the alkali metal orthophosphate comprises trisodium orthophosphate dodecahydrate.

13. Paper or cardboard treated by the process of claim 1.

14. The process according to claim 1, wherein the pH is between 3 and 6.

15. A process for improving the wet rub resistance of a paper or cardboard, comprising the step of contacting the paper or cardboard with an aqueous insolubilizer composition, wherein the aqueous insolubilizer composition comprises glyoxal and at least one alkali metal orthophosphate and wherein the pH of the aqueous insolubilizer composition is below 7.

Description

EXAMPLE 1

(1) Mixed, with stirring at room temperature, are: 112 g of a commercial aqueous 40 wt % glyoxal solution (Clariant), 30 g of 85 wt % phosphoric acid, 37 g of trisodium orthophosphate dodecahydrate, 88 g of water.

(2) A clear solution is obtained having a pH of 3.5, a 37% solids content and a content of glyoxal 40 as such of 42%.

(3) The trisodium phosphate dodecahydrate/glyoxal weight ratio is 0.83.

APPLICATION EXAMPLES

(4) 1/ Size Press Treatment

(5) This treatment is carried out on a size press, comprising an assembly of rolls and between which the sheet passes to receive a uniform coating of slip.

(6) A 14 wt % solution of oxidized starch C*5591 from Cerestar was used.

(7) Various formulations C1 to C6 were prepared whose compositions are given in Table 1 below. The quantities are expressed in g of product as such.

(8) The formulation C1 does not contain insolubilizer.

(9) The formulations C4 to C6 correspond to the use of an insolubilizer composition as described in Example 1.

(10) The formulations C2 and C3, as comparative examples, correspond to the use of a composition as described in EP-A-0 637 644 and having the following characteristics: pH=3.5+/0.5; solids content=42+/1%; content of glyoxal 40 as such=86%; sodium tetraborate decahydrate/glyoxal weight ratio=0.10.

(11) TABLE-US-00001 TABLE 1 C1 C2 C3 C4 C5 C6 Starch 200 200 200 200 200 200 Insolubilizer 3.5 7 (Comparative example) Insolubilizer 3.5 7 14 (Example 1) Proportion 5% 10% 5% 10% 20% (Dry insolubilizer/dry starch)

(12) In the examples, an uncoated wood-free paper was used, having a basis weight of 80 g/m.sup.2, a Cobb.sub.60 of 34.7 seconds and sold by ArjoWiggins.

(13) Impregnation of the paper was carried out with the formulations C1 to C6, with a pick-up of about 20% as such using an SP 350 size press from Mathis, at a rate of 12 m/min and a pressure of 3 bar, followed by drying at 90 C. for 90 s. The Taber wet rub was then determined for the impregnated paper.

(14) The Taber wet rub was carried out according to the modified French standard Q 03-055, with annular test pieces of exterior and interior diameters respectively of 120 and 7 mm, for 10 cycles and 20 cycles, CS-0 abrading wheels, under a pressure of 100 g, in the presence of 10 g of water, followed by rinsing with 10 g of water; these 20 g of water are recovered and made up to 25 g with water, then the turbidity of these 25 g of water is determined with a Hach turbidimeter. The turbidity observed is expressed in NTU units and the results obtained are in Table 2 below.

(15) TABLE-US-00002 TABLE 2 C1 C2 C3 C4 C5 C6 Turbidity 10 cycles 87 17.5 13.5 22.5 10 7 (NTU) Turbidity 20 cycles 170 65 45 68 53 20 (NTU)

(16) The results show that the composition of the invention has a starch-insolubilizing effect.

(17) Furthermore, the results obtained show that the composition of the invention bestows wet rub resistance performances that are at least equivalent relative to the composition of the prior art, for the same quantity of active ingredient.

(18) 2/ Coating Treatment

(19) A calcium carbonate sold by Omya, reference HYDROCARB 90, a kaolin sold by Huber Engineered Materials, reference HYDRAGLOSS 90, an SBR (styrene-butadiene) latex sold by Dow, reference DL 950, and an oxidized starch sold by Cerestar, reference C*5591, were used.

(20) Various formulations C7 to C11 were prepared whose compositions are given in Table 3 below. The quantities are expressed in g of product as such.

(21) The formulation C7 does not contain insolubilizer.

(22) The formulations C10 and C11 correspond to the use of an insolubilizer composition as described in Example 1.

(23) The formulations C8 and C9, as comparative examples, correspond to the use of a composition as described in EP-A-0 637 644 and having the following characteristics: pH=3.5+/0.5; solids content=42+/1%; content of glyoxal 40 as such=86%; sodium tetraborate decahydrate/glyoxal weight ratio=0.10.

(24) TABLE-US-00003 TABLE 3 C7 C8 C9 C10 C11 Calcium carbonate 70 70 70 70 70 Kaolin 30 30 30 30 30 Latex 10 10 10 10 10 Starch 2 2 2 2 2 Insolubilizer 0.4 0.8 (Comparative example) Insolubilizer 0.4 0.8 (Example 1)

(25) In the examples, an uncoated wood-free paper was used, having a basis weight of 80 g/m.sup.2, a Cobb.sub.60 of 34.7 seconds and sold by ArjoWiggins.

(26) Coating of the paper was carried out with the formulations C7-C11, with a deposit of about 20 g/m.sup.2 using a Champion 010 coating bar, followed by drying at 105 C. in an oven for 1 minute. The Taber wet rub was then determined for the impregnated paper as described previously. A turbidity measurement was also carried out after oven treatment at 105 C., for 20 minutes in the press.

(27) Whiteness measurements WCIE were also carried out using Minolta CM 3720/lamp D65/10 equipment.

(28) The results obtained are reported in Table 4 below.

(29) TABLE-US-00004 TABLE 4 C7 C8 C9 C10 C11 Turbidity - 10 cycles before oven 193 113 110 75 67 treatment (NTU) Turbidity - 10 cycles after oven 88 74 67 63 48 treatment (NTU) Whiteness 84.2 83.6 84.5 83.5 85 (%)

(30) The results obtained show that the insolubilizer composition of the invention, used in the coating treatment of paper, has advantageous properties regarding the resistance of the treated paper to wet rub.

(31) It may also be observed that the compositions of the invention do not spoil the whiteness of the treated papers.