Starch-based aqueous adhesive composition

Abstract

The present invention relates to an aqueous adhesive composition comprising: - a) starch treated with a starch maltase or maltodextrin treated with a starch maltase; and - b) ammonium zirconium carbonate.

Description

[0001] This invention relates to starch-based aqueous adhesive compositions.

[0002] The present invention also relates to the use of starch-based aqueous compositions in the manufacture of tubes / cores.

[0003] background

[0004] Homopolymer polyvinyl acetate (PVAc) dispersions have been widely used and established for many years in the industrial bonding of paper, wood or paperboard, such as in the rigid packaging or core / tube manufacturing sectors.

[0005] A cardboard core or paper core is a hollow tube made of one or more layers of cardboard or paper. These cores are formed by winding a material such as paper or cardboard onto a cylindrical mandrel at a given wind angle, winding the material such that each winding at least partially overlaps the previous winding, and adhering it to itself at the seams or overlaps to create a cylindrical core. Such cores are commonly used in rolled products, where the rolled product is wound around the core. Examples include cores used for tissues, toilet paper, or to protect wine bottles.

[0006] These cores / tubes are typically manufactured using industrial continuous processes, particularly through a core-winding process. To meet the constraints of high-speed continuous processes used in industry, water-based adhesive compositions are expected to have rapid setting times; in other words, the ability to quickly solidify the bond immediately after they are applied and form two substrate assemblies and to maintain that bond after a brief application of pressure.

[0007] This PVAc dispersion typically allows for rapid solidification times. However, there is a need for a more environmentally friendly dispersion.

[0008] Such alternatives exist, which are aqueous solutions of dextrin or starch. However, these solutions do not allow for rapid solidification times, resulting in poor productivity in industrial processes.

[0009] Therefore, there is a need for novel environmentally friendly adhesive compositions that exhibit rapid setting times.

[0010] In particular, there is a need for novel environmentally friendly adhesive compositions that offer a good trade-off between adhesive properties and rapid curing time, especially for assembling paper or paperboard substrates.

[0011] Invention Description

[0012] This invention relates to an aqueous adhesive composition comprising:

[0013] -a) Starch treated with starch maltase or maltodextrin treated with starch maltase; and

[0014] -b) Ammonium zirconium carbonate (AZC).

[0015] Starch treated with starch maltase can be obtained from natural starch containing 15% to 30% by weight of amylose and 70% to 85% by weight of amylopectin, the weight percentages being based on the total weight of the natural starch.

[0016] The content of amylose can be determined by the "blue value" method described by Batey Ian et al., "Measurement of amylose / amylopectin ratio by high performance liquid chromatography", Vol. 48, No. 9, pp. 338-344, 1996.

[0017] Maltodextrin is known to be an enzymatic derivative of natural starch. The enzymatic process used to obtain maltodextrin from natural starch is well known to those skilled in the art.

[0018] Maltodextrins are typically classified by their "glucose equivalent" (called DE), which indicates the average degree of polymerization of starch sugars. Generally, maltodextrins have the following glucose equivalents:

[0019] 0 < DE (maltodextrin) < 20

[0020] Natural starch has a glucose equivalent of zero.

[0021] Glucose equivalents can be measured according to standard NF EN ISO 5377 (1994).

[0022] Maltodextrin treated with starch maltase can be obtained from low-DE maltodextrin with a glucose equivalent (DE) of less than 10 (0 < DE < 10), and more preferably less than 5 (0 < DE < 5).

[0023] Low-DE maltodextrin with a glucose equivalent (DE) of less than 10, more preferably less than 5, can be derived from natural starch, preferably from waxy natural starch containing more than 95% by weight of amylopectin, based on the total weight of natural starch.

[0024] The natural starch can be selected from potato starch, wheat starch, corn starch, rice starch, pea starch, tapioca starch, wrinkled pea starch, mung bean starch, and mixtures thereof. Preferably, the natural starch is potato starch.

[0025] Low-DE maltodextrin with a glucose equivalent (DE) of less than 10 (0 < DE < 10), and more preferably less than 5 (0 < DE < 5), can be obtained after treatment of natural starches selected from waxy starches such as potato starch or waxy corn (starch) (after treatment with a starch hydrolase such as amylase).

[0026] Compared to the total weight of the aqueous adhesive composition, the aqueous adhesive composition may contain 20% to 60% by weight, preferably 25% to 55% by weight, and even more preferably 30% to 50% by weight (expressed as dry content) of starch treated with starch maltase or maltodextrin treated with starch maltase.

[0027] Starch treated with starch maltase can be obtained according to the method disclosed in EP0932444. Starch containing amylose can be converted into amylopectin with elongated chains by α-1-4,α1-4 glucan transferase (starch maltase EC 2.4.1.25). The typical and relevant activity of starch maltase lies in the disruption of α-1,4 bonds. This starch maltase does not degrade starch, but reattaches amylose to amylopectin. Finally, the amylose is reattached to amylopectin, producing the desired product. This product can form a thermally reversible gel at low concentrations in water.

[0028] For example, starch treated with starch maltase can be prepared from a suspension of potato starch in water (19-20% w / w). The suspension can be spray-cooked at 150-160°C to dissolve the starch. The product is cooled to 70°C under vacuum, and the pH is then adjusted to 6.2 using, for example, 6N H₂SO₄. Starch maltase (2 ATU / g starch) can then be added. The solution can be stirred at 70°C for 2 to 20 hours. The solution can then be spray-cooked briefly at 130°C and spray-dried using, for example, a compact spray dryer (Anhydro, Danmark).

[0029] According to the present invention, starch treated with starch maltase is starch treated with starch maltase at least. Where starch maltase treatment is not mentioned in relation to starch, the starch may be natural starch, but not treated with starch maltase.

[0030] According to the present invention, maltodextrin treated with starch maltase is maltodextrin that has been treated with starch maltase at least once. Where starch maltase treatment is not mentioned in relation to maltodextrin, the maltodextrin has not been treated with starch maltase.

[0031] A suitable example of starch treated with starch maltase is Etenia from Avebe. TM Starch, such as, for example, ETENIATM 271.

[0032] Compared to the total weight of the aqueous adhesive composition, the aqueous composition may contain more than 40% by weight of water, preferably more than 45% by weight of water, and even more preferably more than 50% by weight of water.

[0033] Compared to the total weight of the aqueous adhesive composition, the aqueous adhesive composition may contain 0.10% to 1% by weight, preferably 0.20% to 0.80% by weight, of ammonium zirconium carbonate (dry matter).

[0034] Ammonium zirconium carbonate can be incorporated into the aqueous adhesive composition as an aqueous solution. Aqueous solutions of ammonium zirconium carbonate are, for example, commercially available from Polycoating under the trade name Vernetzer AZC, or from Brenntag under the trade name Zirlink. Based on the total weight of the aqueous solution, the content of ammonium zirconium carbonate (expressed as ZrO2) in the aqueous solution can range from 15% to 25% by weight, preferably from 18% to 22%.

[0035] The aqueous adhesive composition may contain at least one additive selected from biological agents, defoamers, plasticizers, rheology modifiers, colorants, wetting agents, pH adjusters, inorganic fillers, and mixtures thereof.

[0036] The total content of additives can range from 0.1% to 1% by weight relative to the total weight of the water-based adhesive composition.

[0037] In a preferred embodiment, the water-based adhesive composition is free of boron compounds, such as boric acid or borax. Borax and boric acid are known to be toxic and environmentally unfriendly, therefore the use of such components in the water-based adhesive composition is preferably avoided.

[0038] The aqueous adhesive composition has a viscosity in the range of 100 mPa·s to 5000 mPa·s, preferably 300 mPa·s to 1000 mPa·s, at 23°C. This viscosity was measured using a Brookfield RVT viscometer.

[0039] The aqueous adhesive composition may have a pH in the range of 7 to 10, and more preferably 8 to 9, at 23°C.

[0040] The present invention also relates to a method for preparing the aqueous adhesive composition disclosed above.

[0041] This aqueous binder composition can be prepared by mixing a) starch treated with starch maltase or maltodextrin treated with starch maltase with b) ammonium zirconium carbonate, and optional additives, with water. The mixing can be carried out at 23°C.

[0042] The present invention also relates to the use of the aqueous adhesive compositions disclosed above in the manufacture of rigid packaging or tubes.

[0043] In one embodiment, the aqueous adhesive composition according to the invention is used to manufacture tubes / cores by winding. These tubes can be used, for example, to manufacture tissues, toilet paper, or bottle protectors. Preferably, the tube / core is made of paper or cardboard.

[0044] According to the present invention, "between x and y" or "within the range of x to y" indicates a range that includes the boundaries x and y. For example, the range "between 1% and 3%" specifically includes 1% and 3%.

[0045] Experimental Section

[0046] Viscosity

[0047] The viscosity of the composition was determined after 15 s at 20 RPM and 23 °C (±1 °C) using a Brookfield DV-I digital viscometer (mPa.s) with the correct applicable rotor (e.g., rotor 2).

[0048] pH value

[0049] After calibrating the electrodes to pH 7 and 10 with buffer solutions, the pH values ​​were measured at 23°C (±1°C) using a pH / thermometer TESTO 230.

[0050] Bonding and setting time

[0051] The setting time of the water-based adhesive composition was determined using a FIPAGO adhesive strength tester (System PKL) in an air-conditioned room (RH = 50 ± 5%, T = 23℃ ± 2℃).

[0052] Sample preparation: Prior to testing, allow the adhesive to stand in a controlled room at RH = 50 ± 5% and T = 23 °C ± 2 °C for at least 24 hours. (The adhesive was obtained from Fipago 2006 paper (Stohlein, 200 g / m²)). 2 Cobb 1800: 86g / m 2 Cut the following strips from the top:

[0053] -30×200mm paper tape, on which an adhesive water-based composition will be applied.

[0054] -60×100mm paper tape, which will be placed in the FIPAGO adhesive strength tester.

[0055] A film of the water-based adhesive composition was applied to a 30×200 paper tape using a roller coater at a rate of 55 g / sqm (±5 g / sqm) = 0.31-0.35 g / sqm. A 60×100 mm paper tape was fixed horizontally on a ramp of the measuring machine, which was connected to a moving arm capable of pendulum motion around a pivot. One end of the 30×200 paper tape (approximately 2 cm in length) was brought into contact with a fixed bearing connected to the machine, coplanar and adjacent to the former, through its side coated with the water-based adhesive composition. The largest portion of the 30×200 paper tape was then coated onto the 60×100 paper tape and automatically and evenly pressed onto the latter by the machine's pressing device. This pressing was performed 5 seconds after the tape was coated (drying time). The bonded assembly was then broken by triggering the pendulum motion of the moving arm, causing the two substrates to separate.

[0056] The solidification time is the shortest time to exceed 70 mmKp (0.69 J) of energy under a 5-second setting time.

[0057] Example 1: Preparation of water-based adhesive composition C1

[0058] The following components are used to prepare aqueous adhesive compositions:

[0059] ETENIA TM 271: Starch treated with starch maltase, commercially available from AVEBE NL.

[0060] AZC: A commercially available solution of ammonium zirconium carbonate (AZC) from POLYCOATING GmbH, containing 20% ​​AZC as ZrO2;

[0061] 301 (Defoamer): A mixture of vegetable oil, modified fatty compounds, nonionic emulsifiers, and a small amount of silicone. Commercialization of CHEMIE ABSATT;

[0062] MBS (biocide): A mixture of 1,2-benzisothiazolin-3-one (BIT) and 2-methyl-4-isothiazolin-3-one (MIT), commercialized by THOR.

[0063] The following composition was prepared as follows, the components and amounts of which are mentioned in the table below: 40g ETENIA TM 271 was slowly dispersed in 58.7 ml of water and homogenized until a clear appearance was obtained (time: 1 h). AZC was added, and the mixture was mixed at 23 °C for 15 min. Subsequently, 0.2 g was added. MBS (biocide) and 0.1g AGITAN (Defoamer) was added, and the mixture was stirred at 23°C for 1 hour. The viscosity was measured, and additional water was added to achieve a viscosity of 500 mPa·s at 23°C.

[0064] Table 1: Aqueous Adhesive Compositions C1

[0065]

[0066] Table 1 shows that the aqueous adhesive composition (C1) according to the invention advantageously exhibits a setting time of 29 s. This short setting time advantageously allows for improved production line speed, and thereby improved productivity.

Claims

1. An aqueous adhesive composition comprising, relative to the total weight of the aqueous adhesive composition: - a) 20 to 60 wt% of starch treated with a starch maltase EC 2.4.1.25 or maltodextrin treated with a starch maltase EC 2.4.1.25; and - b) zirconium ammonium carbonate, wherein the maltodextrin treated with a starch maltase EC 2.4.1.25 is obtained from a low DE maltodextrin having a dextrose equivalent (DE) of 0 < DE < 10.

2. The aqueous adhesive composition according to claim 1, wherein the starch treated with a starch maltase EC 2.4.1.25 is obtained from a native starch comprising 15 to 30 wt% of amylose and 70 to 85 wt% of amylopectin, the weight percentages being based on the total weight of the native starch.

3. The aqueous adhesive composition according to claim 2, wherein the native starch is selected from the group consisting of potato starch, wheat starch, corn starch, rice starch, pea starch, tapioca starch, mung bean starch and mixtures thereof.

4. The aqueous adhesive composition according to claim 2 or 3, wherein the native starch is potato starch.

5. The aqueous adhesive composition according to claim 1, wherein the low DE maltodextrin has a dextrose equivalent of 0 < DE < 5.

6. The aqueous adhesive composition according to claim 1 or 2, comprising 25 to 55 wt% of the starch treated with a starch maltase EC 2.4.1.25 or the maltodextrin treated with a starch maltase EC 2.4.1.25, relative to the total weight of the aqueous adhesive composition.

7. The aqueous adhesive composition according to claim 1 or 2, comprising 30 to 50 wt% of the starch treated with a starch maltase EC 2.4.1.25 or the maltodextrin treated with a starch maltase EC 2.4.1.25, relative to the total weight of the aqueous adhesive composition.

8. The aqueous adhesive composition according to claim 1 or 2, comprising more than 40 wt% of water, relative to the total weight of the aqueous adhesive composition.

9. The aqueous adhesive composition according to claim 1 or 2, comprising more than 45 wt% of water, relative to the total weight of the aqueous adhesive composition.

10. The aqueous adhesive composition according to claim 1 or 2, comprising more than 50 wt% of water, relative to the total weight of the aqueous adhesive composition.

11. The aqueous adhesive composition according to claim 1 or 2, comprising 0.10 to 1.0 wt% of zirconium ammonium carbonate (dry matter), relative to the total weight of the aqueous adhesive composition.

12. The aqueous adhesive composition according to claim 1 or 2, comprising 0.20 to 0.80 wt% of zirconium ammonium carbonate (dry matter), relative to the total weight of the aqueous adhesive composition.

13. The aqueous adhesive composition according to claim 1 or 2, comprising at least one additive selected from the group consisting of biocides, antifoams, plasticizers, rheology modifiers, colorants, wetting agents, pH adjusters, inorganic fillers, and mixtures thereof.

14. The aqueous binder composition according to claim 1 or 2, characterized in that which is free of boron compounds.

15. The aqueous adhesive composition according to claim 1 or 2, having a viscosity in the range of 100 mPa.s to 5 000 mPa.s at 23 °C.

16. The aqueous adhesive composition according to claim 1 or 2, having a viscosity in the range of 300 mPa.s to 1 000 mPa.s at 23 °C.

17. The aqueous adhesive composition according to claim 1 or 2, having a pH in the range of 7 to 10.

18. The aqueous adhesive composition according to claim 1 or 2, having a pH in the range of 8 to 9.

19. Use of the aqueous adhesive composition according to any one of claims 1 to 18 for the manufacture of rigid packages or tubes.

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