A material with enhanced water and / or grease repellency, method for its manufacture and use

Abstract

A material with enhanced water and / or grease repellency, method for enhancing the water and / or grease repellency, a product therefrom and use is disclosed.

Description

[0001] A material with enhanced water and / or grease repellency, method for its manufacture and use

[0002] Field of the invention

[0003] The present invention relates to a material with enhanced water and / or grease repellency, a method for of enhancing the water and / or grease repellency in a material, preferably containing cellulosic fibers, and product therefrom and use thereof. The product, which may multi-layered (such as three layered) may be used for press molding of a fiber product, intended to be formed at high pressure and high temperature, preferably by means of a press pad device and a stamp device, wherein said material results in a fiber product with enhanced water and / or grease repellency. Also, the present invention provides a sustainable, and applicable at industrial scale, method to increase the water and / or grease repellency of the abovementioned treated cellulosic material, without the use of additional chemicals.

[0004] Background

[0005] Water or grease repellent may be applied on cellulosic materials and e.g. AKD, ASA, or waxes have been used for a long time in the papermaking field, and countless articles and studies have been published on mechanisms associated to these agents.

[0006] The material used to form lids and closures, if e.g. using a cellulosic material, are normally bulky (such as 7 - 8 cm3 / g) with loosely held fibres and extremely high porosity. These parameters may further be enhanced by the usage of a decurler unit before the pressing of the object, which breaks bonds between fibres to facilitate shaping of the fibre mat. Consequently, hydrophobic agents added to the fibre mat are on the one hand able to spread through the structure of the material and bring hydrophobicity thanks to high porosity and specific surface, but cannot form a full network, either through crosslinking, polymerisation, or coalescence due to the high porosity and additional de-structuration from the decurler unit. However, the high porosity of the cellulosic material may also lead to easy water uptake from the ambient air relative humidity, and therefore this could mean hydrolysis and loss of the hydrophobic agent in the case of e.g. AKD.

[0007] Thus, there is still need for providing a simplified method for making water or grease repellent material useful in products beneficial for packaging solutions, especially in the food and beverage areas. Also, there is a need for a method that is sustainable, applicable at industrial scale, for increasing the water and I or grease repellency of the abovementioned treated cellulosic material, without the use of additional chemicals.

[0008] Summary of the invention

[0009] The present invention solves / alleviates one or more of the problems set out above by providing according to a first aspect a material, preferably containing cellulosic fibers, with enhanced water and / or grease repellency, suitable for packaging purposes, having a density of from about 1.11 to about 1.25 kg / dm3, wherein preferably said enhanced repellency is achieved using one or more water and / or grease repellents, preferably one or more sizing agents.

[0010] Also, according to a second aspect a method for enhancing the water and / or grease repellency in a material, suitable for packaging purposes, comprising the following steps is provided: a) providing a material, preferably containing cellulosic fibres, b) passing said material through a decurler unit, c) spraying a water and / or grease repellent on said treated material (i.e. on the material treated by the decurler), d) subjecting said treated material to high pressure and to high temperature, thus providing a product with enhanced water and / or grease repellency (i.e. hydrophobicity and / or oleophobicity), useful e.g. in packaging solutions for food or beverages.

[0011] The decurler (or decurler unit) has a mechanical effect on the fibers, which means that any bending present on said fibers initially, may essentially be removed using the decurler.

[0012] Also, according to a third aspect of the present invention there is provided a product with enhanced water and / or grease repellency (i.e. hydrophobicity and / or oleophobicity), obtainable by a method according to the second aspect.

[0013] Also, according to a fourth aspect of the present invention there is provided use of a material or a product with enhanced the water and / or grease repellency (i.e. hydrophobicity and / or oleophobicity) according to the first or third aspect wherein said product is / are a part(s) of a moulded product, such as a screw cap, a container, a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or auto-clave package or a tray, ora plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard.

[0014] Also, according to a fifth aspect of the present invention there is provided use of a material or a product with enhanced water and / or grease repellency (i.e. hydrophobicity and / or oleophobicity) according to the first or third aspect, in a multi-layered, such as three-layered, moulded product, such as a screw cap, a container a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or auto-clave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard, wherein preferably the layer with enhanced water and / or grease repellency is facing the food or beverage during the final usage of the consumer.

[0015] Detailed description of the invention

[0016] The expressions “fibre” or “fiber” may be used interchangeably in the present specification and would have the same meaning.

[0017] Decurler-units that may be used in connection with the above-mentioned method according to the second aspect may be e.g. a roll-decurl component provided by Maxson Automatic Machinery Company or a decurl unit provided by Ricoh. These are only non-limiting examples. Said decurl unit may comprise one sponge roller, two metal rollers and two paths for paper or other cellulosic material. The decurl strength and curl direction may be adjusted. There may be a “sandwich” configuration wherein there is an upper pressure roller, a decurl roller and a lower pressure roller.

[0018] According to a preferred embodiment of the second aspect the high pressure and high temperature of step d) is provided by a press pad device and a stamp device.

[0019] According to a preferred embodiment of the second aspect the high pressure and high step d) is a combination of a pressure of from about 10 to about 100 MPa, preferably from about 20 to about 30 MPa, and a temperature of from about 120 to about 250 °C, preferably from about 120 to about 180 °C, whereby preferably said conditions is upheld during a time period of from about 0.5 to about 2 s. According to a preferred embodiment of the second aspect the material emanates from CTMP (ChemiThermo Mechanical Pulp), TMP (Thermo Mechanical Pulp), Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof.

[0020] According to a preferred embodiment of the second aspect the material emanates from bleached or non-bleached pulp, or a combination thereof.

[0021] According to a preferred embodiment of the second aspect the material emanates from hardwood or softwood, bagasse, algae or straw or a combination thereof.

[0022] According to a preferred embodiment of the second aspect the material provided in step a) is an air-laid material, preferably containing cellulosic fibers, or a wet material, preferably containing cellulosic fibers, or a combination thereof, wherein preferably said material provided in step a) has a specific volume of from about 7 to about 8 cm3 / g. Said air-laid material may comprise long fibered softwood and it may be a fluff pulp in roll form originally which is shredded (defibridized) e.g. in a hammermill. Normally an air-laid web (such as a paper) may consist of 85% fiber. The remaining percentage may be a binder and / or one or more additive, which may be applied through using spray or foam. ccording to a preferred embodiment of the second aspect said water and / or grease repellent is one or more sizing agents, preferably selected from the group comprising AKD (alkylketendimer), ASA (alkenyl succinic anhydride) and waxes or a combination thereof.

[0023] According to a preferred embodiment of the second aspect said method provides a product according to the first aspect.

[0024] According to a preferred embodiment of the fourth aspect said multilayer product is provided so that one of the outer layers form threads or click-on function for sealable packaging, for example a container, a closure or a part of container or closure.

[0025] Preferred features of each aspect of the invention are as for each of the other aspects mutatis mutandis. The invention is further described in the following example with figures which do not limit the scope of the invention in any way.

[0026] Embodiments of the present invention are described as mentioned in more detail with the aid of examples of embodiments and figures the only purpose of which is to illustrate the invention and are in no way intended to limit its extent. Figures

[0027] Fig. 1 - 3 show pressing when making closure suitable for use on a bottle

[0028] Fig. 4 - 5 show hydrophobicity for lids

[0029] Fig. 6 shows hydrophobicity for closures

[0030] Examples

[0031] In the provided method according to the second aspect of the present invention, i.e. the method for enhancing hydrophobicity and / or oleophobicity of dry-pressed cellulosic material, the bulky cellulosic material may be pressed after going through the decurler unit. The combination of pressure (20 - 30MPa) and heat (120 -180 °C) applied to the material for 0.5 - 2 s yields a high-density cellulose object from about 1.11 to about 1 .25 kg / dm3with limited porosity and a capillary-free structure. Before the pressure and temperature is applied as set out above, a water and / or grease repellent is sprayed on the material that has been processed in the decurler unit. Non-limiting examples of such devices are a roll-decurl component provided by Maxson Automatic Machinery Company or a decurl unit provided by Ricoh.

[0032] This process affects the material in several ways: a) the high temperature at which the material is pressed allows to heat the fibre mat above the melting point of the agent used for water / grease repellency. This allows the agent to redistribute I spread more evenly on I around the fibres during pressing and reach a more homogeneous fibre coverage, and therefore a higher hydrophobicity and I or oleophobicity b) The extremely high densification of the material during pressing yields a smooth, closed surface object with low specific volume when compared to other cellulosic materials such as paperboard or wet moulded cellulose. The densification of the fibre network allows for the creation of a network of hydrophobic and I or oleophobic agent around the fibres that is then locked in the structure due to the lack of available space to flow. Moreover, the smooth, closed surface further reduces the flowing possibility and locks the agent in the material, as well as decrease the possibility of hydrolysis, therefore increasing the performance. Finally, the densification of the material increases the volume fraction of hydrophobic and I or oleophobic agent in a given amount of material, leading to a further densification of the network and increase in performance.

[0033] Trials with hydrophobic materials

[0034] Material treated with various hydrophobic products were manufactured and pressed into lids or screw caps. The materials were one or two sides treated with AKD (AP), wax dispersion (AN), or click chemistry products with (ASCL) and without (AS) additional binder. Percentages (dry / dry) of added hydrophobic product were either 1% or 2%. Layers of materials were superposed before pressing in order to create multilayer materials with varying levels of hydrophobic treatment in and outside. The materials were pressed between 80-140°C using a servo press and screw caps or lid tools depending on the desired geometry.

[0035] The following table summarises the material assemblies that were evaluated. The number (0, 1 , 2) represents the percentage of hydrophobic treatment in each layer.

[0036] All materials performed well both in terms of formation of the 3D object and water repellency. Variations in mechanical performances were observed depending on type and amount of treatment, which may allow to modulate the performances of the final product according to need and specifications.

[0037] Pressing is highlighted in Figures 1 - 3. In figures 4 and 5 it is clearly to be seen the results after hydrophobic treatment as set out above useful as lids. The closure seen in figure 6, was made in a form suitable for usage on a bottle, such as a bottle useful for alcoholic beverage. Various embodiments of the present invention have been described above but a person skilled in the art realizes further minor alterations that would fall into the scope of the present invention. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents. For example, any of the above-noted methods may be combined with other known methods. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains. -

Claims

Claims1. A material, preferably containing cellulosic fibers, with enhanced water and / or grease repellency, suitable for packaging purposes, having a density from about 1.11 to about 1.25 kg / dm3, wherein preferably said enhanced repellency is achieved using one or more water and / or grease repellents, preferably one or more sizing agents.

2. A method for enhancing the water and / or grease repellency in a material, suitable for packaging purposes, comprising the following steps: a) providing a material, preferably containing cellulosic fibres, b) passing said material through a decurler unit, c) spraying a water and / or grease repellent on said treated material, d) subjecting said repellent treated material to high pressure and to high temperature, thus providing a product with enhanced water and / or grease repellency, useful e.g. in packaging solutions for food or beverages.

3. A method according to claim 2 wherein the high pressure and high temperature of step d) is provided by a press pad device and a stamp device.

4. A method according to claim 2 wherein the high pressure and high temperature of step d) is a combination of a pressure of from about 10 to about 100 MPa, preferably from about 20 to about 30 MPa, and a temperature of from about 120 to about 250 °C, preferably from about 120 to about 180 °C, whereby preferably said conditions is upheld during a time period of from about 0.5 to about 2 s.

5. A method according to claim 2 wherein the material emanates from ChemiThermo Mechanical Pulp, Thermo Mechanical Pulp, Kraft pulp, sulfate pulp, sulfite pulp, recycled pulp material, board or carton, or a combination thereof.

6. A method according to claim 2 wherein the material emanates from bleached or non-bleached pulp, or a combination thereof.

7. A method according to claim 2 wherein the material emanates from hardwood or softwood, bagasse, algae or straw or a combination thereof.

8. A method according to claim 2 wherein the material provided in step a) is an air-laid material, preferably containing cellulosic fibers, or a wet material, preferably containing cellulosic fibers, or a combination thereof, wherein preferably said material provided in step a) has a specific volume of from about 7 to about 8 cm3 / g.

9. A method according to claim 2 wherein said water and / or grease repellent is one or more sizing agents, preferably selected from the group comprising alkylketendimer, alkenyl succinic anhydride and waxes or a combination thereof.

10. A method according to claim 2 providing a product according to claim 1.11 . A product with enhanced the water and / or grease repellency, obtainable by a method according to any one of claims 2 -10.

12. Use of a product with enhanced water and / or grease repellency according to claim 11 or a material according to claim 1 , wherein said product / material is / are a part(s) of a moulded product, such as a screw cap, a container, a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or auto-clave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard.

13. Use of a product with enhanced water and / or grease repellency according to claim 11 or a material according to claim 1 , in a multi-layered, such as three-layered, moulded product, such as a screw cap, a container, a bread clip or a package, wherein said container may be a disposable drinking cup or dairy product carton or auto-clave package or a tray, or a plate for eating or keeping food, or a paper or paperboard, such as a folding boxboard, wherein preferably the layer with enhanced water and / or grease repellency is facing the food or beverage during the final usage of the consumer.

14. Use according to claim 13 wherein said multilayer product is provided so that one of the outer layers form threads or click-on function for sealable packaging, for example a container, a closure or a part of container or closure.

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