Patent ID: 12258715

EXPERIMENTAL MATERIALS AND METHODS

The materials used for generating the aqueous coating suspensions were uncooked starch particles (barley, Altia Plc, Finland), hydrophobically modified hydroxyethyl cellulose (EHEC, Bermocoll EHM200, AkzoNobel Chemicals AG, Sweden), and Sodium dodecyl sulfate (SDS, Merck KGaA, Germany). The particle size distribution (by volume) of the uncooked starch particles used is shown in Table 1. The particle size was measured at pH around 7 and at a temperature of 23° C. using a Mastersizer 2000 particle size analyser (Malvern, UK).

TABLE 1D10D50D90Wet sample10.917.426.4(30 min-1 h 30 min)Stdev0.10.00.1

Cupforma classic 210 gsm was used as substrate. The starch was mixed as received without further treatment into cold water. The foam was generated with A Rollmix BGR 13 (Rollmac, Italy). Coating of the substrate was conducted with a bench coater (rod).

pH and viscosity of the aqueous suspensions were measured before generating the foam. Viscosity of the foam was measured with a Brookfield digital viscometer (Model DVII+, Brookfield Engineering Laboratories, Inc.) using spindle #6 and speeds of 10 and 50 rpm at the temperatures given in the tables below. For the measurement of the viscosity of the aqueous suspensions spindle #1 and 50 rpm was used, except sample 6, where 10 rpm were used. Solid content was measured with an IR dryer. Sample amount was about 1 g. The foam density was determined by dividing the measured weight of the foam with the measured volume.

Reference Examples 1 and 2

Reference examples 1 and 2 were performed in which the foaming capacity of aqueous suspensions without addition of a foam generating agent was evaluated in a laboratory trial. The components and properties of the suspensions of reference examples 1 and 2 are summarised in table 2:

TABLE 2Example12Starch, barley, wt %100100EHEC——SDS——Foam generationnonoTemperature, ° C.21.120.8Solids, wt % (in the suspension710before foaming)Coat weightnonoFoam density, g/100 mlBrookfield 10 rpmBrookfield 50 rpmpH (liquid)6.616.67Brookfield 50 rpm, liquid9.29.8Solids of the foam

The suspensions of reference examples 1 and 2 did not foam. This confirms that without additives, no foaming is observed.

Examples 3 to 6

A test series was performed in which the foaming capacity of suspensions comprising uncooked starch particles and amphiphilic polymer in accordance with the invention was evaluated. Experiments were performed using EHEC as foaming agent. The components and properties of the aqueous suspensions of examples 3 to 6 are summarised in table 3:

TABLE 3Example3456Starch, barley, wt %100100100100EHEC, wt %1555SDS————Foam generationyesyesyesyesTemperature, ° C.212320.521Solids, wt %771218Coat weight3.53.84.24.6Foam density, g/100 ml14.5714.982347.56Brookfield 10 rpm2100140022004600Brookfield 50 rpm7604409202360pH (liquid)5.76.26.05.78Brookfield 50 rpm, liquid11.62264.6540Solids of the foam11.5817.15

In addition to pH and viscosity, the solids contents of the foam was measured for examples 5 and 6 providing of aqueous starch solutions with 12 and 18 wt-% solids content, respectively. The solid content was determined with an IR dryer. The sample amount was about 1 g. As can be seen in table 2, the content of starch in the foams of examples 5 and 6 was very high. The EHEC based foams were stable and did not break completely during coating. Further, the breakage of the EHEC foam in coating was more controlled.

The shows that not only foam coating using uncooked starch is possible to use, but that a tenside-free generation of foam can be achieved, yielding a much higher starch content than expected. This is a significant improvement over the prior art technique using SDS as a tenside.

Reference Examples 11 to 14

A further test series was performed in which the foaming behavior of aqueous starch solutions with SDS as foaming agent was evaluated. The components and properties of the aqueous suspensions of reference examples 11 to 14 are summarised in table 4:

TABLE 4Example11121314Starch, barley, wt %100100100100SDS, wt %1555Foam generationpoorpoorpoorpoorTemperature, ° C.21.622.520.621.4Solids, wt %771218Coat weight, gsm2.43.32.42.3Foam density, g/100 ml26.9813.224.4324.95Brookfield 10 rpm84014007001100Brookfield 50 rpm480560460400pH (liquid)6.757.036.926.95Brookfield 50 rpm,99.41111.8liquidSolids of the foam6.056.528.129.9

The foam of reference example 11 using 1 wt % SDS broke almost immediately. However, the foam of reference example 12 using 5 wt % SDS was very stable and did not break when coated with a rod. Increasing the solids content to 12 and 18 wt % in the liquid suspension however did not result in higher solid content of foam when using SDS foams, as can be seen in reference samples 13 and 14 where the solid content of the foams remained low. Also, the water separated quickly. This shows that SDS as foaming agent only provides for poor foam generation with less starch content in the foam.

Reference Examples 15 to 18

A further test series was performed in which the foaming behaviour of aqueous starch solutions without foaming agent was evaluated. The components and properties of the aqueous suspensions of reference examples 15 to 18 are summarised in table 5:

TABLE 5Example15161718Starch, barley, wt %100100100100Foam generationnonononoTemperature21.120.820.521.8Solids, wt %7101218pH (liquid)6.616.676.676.77Brookfield 50 rpm, liquid9.29.810.612.4

This reference examples illustrate the increasing viscosity with increasing solid content.