EP1231322A2 - Self-cleaning anti-adhesive papers and paper materials, and process for making the same - Google Patents

Abstract

A microstructured paper or paper-like material (PPLM) having self-cleaning and anti-adhesive action and peaks and depressions in the surface, the distance between the peaks being 0.04-100 micro m and the peak heights 0.04-100 micro m containing a binder with particle size 0.04-50 micro m and which is hydrophobic over its whole cross section is new. An Independent claim is included for preparation of the microstructured paper with addition of a hydrophilizing agent within the framework of a wet process for treating the PPLM fibers of particle size 0.04-50 micro m and fixing the particles on the fibers with a binder.

Description

The present invention relates to papers and paper-like Materials with self-cleaning and anti-adhesive properties and processes for their production.

Numerous methods are described in the literature to to achieve water, oil and dirt repellent behavior, which also allows self-cleaning. Together is this process that the smoothest possible surface was usually made highly hydrophobic. However, it has shown that the effect is either temporary or inadequate was strongly developed for the technical area.

EP-A-0 772 514 describes that in addition to a strong Additional microstructuring to hydrophobic equipment a clear support for the behavior described above contributes. This phenomenon was found in nature in plants like Nasturtiums or more pronounced in lotus plants observed and described. After that, creating artificial Surface structures from surveys and depressions with Distances between the surveys in the range of 5 - 200 µm, preferably 10 - 100 µm and the height of the surveys in the area 5 - 100 µm, preferably 10 - 50 µm, with the elevations made of hydrophobic polymers or durable hydrophobic materials exist that objects with such artificial Such behavior can be imparted to surfaces can.

However, paper or paper-like material generally has a rather arbitrary and disordered structure that is typical is not flat, but a specific macro structure which should ensure that targeted training the above microstructure becomes impossible.

In particular, the inventors have contributed to the present invention attempting the processes described in EP-A-0 772 514 to form a hydrophobic surface structure on paper apply, found that the achievable effect on paper is insufficient for industrial applications. In particular occurs when water comes into contact with one of those in EP-A-0 772,514 described paper treated a Fiber swelling on, the changes in the microstructure itself draws. In addition, the inventors of the present Invention a penetration of water through a so treated Paper observes what an entry of the dissolved in the water Dirt in the paper or even through it Paper causes.

It was therefore all the more surprising that the inventors of the present invention succeeded for the first time nevertheless, paper or paper-like material with anti-adhesive and / or self-cleaning To produce an effect in which an anti-adhesive and / or self-cleaning behavior is permanently maintained.

The subject of a first aspect of the present invention is thus a micro-structured paper or paper-like material with self-cleaning and / or anti-adhesive effect, the Paper or paper-like material over the entire material cross-section is hydrophobic and is so microstructured, that the surface has elevations and depressions, wherein the distance between the surveys in the range of 0.04 to 100 µm and the height of the surveys in the range from 0.04 to 100 µm lie, the paper or paper-like material thereby is labeled with a binder on the paper or paper-like material bound particles of a particle size contains from 0.04 to 50 µm.

We understand paper or paper-like materials materials such as paper, metallized paper, Cardboard, cardboard, cardboard boxes and nonwovens, but not textiles.

In a preferred embodiment of the first aspect of the present invention is the distance between the elevations on the surface of such a microstructured paper or paper-like material in the range of 0.04 to 50 µm, especially preferably in a range from 0.04 to 20 μm. In another preferred embodiment is the height of the surveys the surface of such a microstructured paper or paper-like material in the range of 0.04 to 50 µm, especially preferably in a range from 0.04 to 20 μm.

It is further preferred according to the invention that the paper or paper-like material is also oleophobic. Thus in preferably the paper or paper-like material both oleophobic as well as hydrophobic.

According to a preferred embodiment of the first aspect of the present invention is the paper according to the invention or paper-like material further characterized in that water drops on the surface of the paper or paper-like Do not stick the material, but roll it off permanently. This can be determined according to the invention that a on the Surface of a 40 °, preferably 10 ° from the horizontal inclined paper or paper-like material according to the invention deposited, 20µl large water drops and therefore not sticks to the surface.

Furthermore, the paper or paper-like material according to one another preferred embodiment of the first aspect of Present invention characterized in that there is a Moisture resistance of more than 10 minutes, preferably of more than 30 minutes. This moisture resistance was determined according to the invention in that the test item Paper or paper-like material on a blotter is placed on what is to be examined on the surface Material stained a 20 µl drop of water and put on the surface is left standing. After 10 minutes or equivalent later the underlaid blotting paper is visually inspected. If the staining sheet is not visible, one speaks according to the invention of moisture stability the elapsed time.

Furthermore, the paper or paper-like material according to the invention preferably characterized by resistance to fiber swelling. According to the invention, this can be determined by according to the procedure described for the moisture stability after removing the drop after 30 minutes from the test sample Paper surface the surface of the paper or paper-like Visually material on swelling of the fibers is examined. The fibers can be swollen for example by curling the paper or paper-like Recognize materials. If this curl does not occur, it will Paper or paper-like material according to the invention as traveling designated against fiber swelling.

In a preferred embodiment of the first aspect of present invention has the paper or paper-like material a contact angle with water greater than 120 °, preferably greater than 140 °. According to the invention was used to measure the contact angle a 20 µl drop of water at room temperature the paper or paper-like material is applied and with the help a commercially available contact angle measuring device, for example such a contact angle determined by Krüss.

Other properties of the paper or paper-like material, such as basis weight, strength or thickness can be in the A person skilled in the relevant art is known without Difficulties depending on the desired application to adjust.

Another aspect of the present invention is the subject of a method of making a microstructured, about the entire material cross section of hydrophobic paper or paper-like material with self-cleaning and / or anti-adhesive Effect that on the surface elevations and depressions has, the distance between the elevations in Range from 0.04 to 100 µm and the height of the surveys in the Range from 0.04 to 100 microns, the process thereby is characterized in that with the use of a hydrophobizing agent the fibers of the Paper or paper-like material particles of a particle size from 0.04 to 50 µm and the particles attached to it Fibers are fixed with a binder.

In principle, it is irrelevant for the method according to the invention which of the available wet laying procedures for Application comes. This can be a procedure below Use of a paper machine with long, round or inclined screen act. The paper machine can have a single or multi-headbox be equipped. The paper machine can also a through-flow, contact and / or contactless drying device be equipped. For contactless drying it can be UV or IR drying.

In a preferred embodiment, the fibers used by those skilled in the relevant art known natural or synthetic fibers, for example natural fibers from softwood or hardwood, such as cellulose fibers, for example fibers with a fiber diameter of 2 to 50 microns. In the case of the use of plastic fibers, it can in the case of synthetic fibers around those made of polypropylene (PP), polyvinyl acetate, Polyethylene (PE) or polylactic acid (PLA) or Bicomponent fibers made of polypropylene, polyethylene (PE), such as high density polyethylene, polyvinyl acetate, such as polyethylene vinyl acetate and / or act polylactic acid.

In a further preferred embodiment, it can be the fibers to be used are, for example which surveys with the necessary sizes by suitable Polymers, for example, by grafting them onto the basic fibers were trained in a manner known per se to the person skilled in the art. in this connection can, for example, by grafting suitable polymers Chemical grafting done. Furthermore, instead of being grafted on Fibers filled synthetic fibers by built-in fillers a microstructured surface as defined above have used. Microporous fibers can also be used Polymers such as Accurel fibers from Acordis are used become.

According to the invention, it was surprisingly found that on paper or paper-like materials by the introduction of particles with a particle size of 0.04 to 50 µm the desired Microstructure on the paper surface as well as over the Material cross section formed according to the above statements can be.

The particles which can be used according to the invention are particles according to the invention, the size of which is preferably between 0.04 and 50 microns, in particular between 0.08 and 30 microns. According to the invention, particles of the same type can, however different particle size, different type, but same particle size and different types and use different particle sizes combined.

Alternatively, the particles can form during leaf formation Stock suspension or additionally according to the invention on one elsewhere in the paper machine, for example also over Spray bars or a size press can be added.

In a preferred embodiment, the particles for example, be added directly to the fiber suspension. In this way, if they are sufficiently soluble or appropriate dispersibility in the headbox if necessary using a dispersant and / or a retention aid be applied.

Surprisingly, hydrophilic particles accumulate when added into the bulk due to screen drainage on one side of the Paper web.

Usually hydrophobic particles, as far as they are in a added or introduced aqueous solution onto the paper web in the form of a surfactant Dispersion used. Surprisingly, accumulate due to the hydrophobic particles when added to the mass screen drainage on one side of the paper web.

In a further preferred embodiment, the particles alternatively or in addition to the addition to the headbox and / or via a spreading box via a roller application process, e.g. applied to the paper web via a size press application become.

For connecting or fixing the particles to the fibers Binders known to the papermaker according to the invention, e.g. Latex, acrylate and / or styrene binder and / or bulk sizing agent, used.

According to the invention, the binders are usually in one Amount of 1 to 20%, based on the paper weight, preferably added in an amount of 2 to 15%.

In particular, it should be ensured according to the invention that the use of the binders described above the desired Surface structure of the paper or paper-like Material is not extinguished.

The selection of the application method also determines on which side the corresponding microstructure the particle is generated.

The particles are usually inorganic compounds such as metal oxides (such as aluminum oxide, iron oxide), corundum (this is α-aluminum oxide), silicon dioxide, quartz, quartz powder, silica sols, pigments such as TiO ₂ , carbonates and sulfates, preferably calcium carbonate, Calcium sulfate, barium sulfate, silica, kaolin or talc. In a preferred embodiment, the particles to be used according to the invention are silicon dioxide, quartz particles or other SiO ₂ -containing solids.

In addition to the mineral components described above are also organic particles such as wood (wood flour) or synthetic Particles such as Plastic pigments or polymer powder, such as Teflon powder suitable. Teflon powder offers the advantage of one extremely pronounced water repellent and oil repellent effect.

The exact design of the surface structure is determined by the size and concentration of the respective particles.

The particles are usually present in an amount of 5 to 65%, preferably 10 to 50%, based on the basis weight of the Paper or paper-like material, added.

There is also the possibility of combining certain Particles to create an individual microstructure grid different crystallization forms and microstructures be deliberately superimposed.

For example, particles with different particle sizes and crystal shapes or crystallization forms can be mixed or overlaid with other particles, for example SiO ₂ particles can be overlaid with nanoparticles, such as those found in silica sols. The nanoparticles can, for example, be contained in a hydro- and / or oleophobicizing agent, or can be generated by the hydro- and / or oleophobicizing agent.

A hydrophobization of the paper or paper-like material can by using hydrophobic agents such as hydrophobic starches, water-insoluble fats, natural Waxing, synthetic waxing, e.g. Montan type, White oil, paraffin and their gasses, resins, silicones, silanes, Siloxanes, phosphoric acid esters, dicarboxylic acid derivatives, partial esters of polyalcohols, citric acid esters, oxalkylated Fatty acids and alcohols, paraffin oxidates, chromium fatty acid complexes, Chromium and aluminum alkyl phosphates, organotin compounds, Fluorocarbon compounds, quaternary organic Compounds, or achieve urea derivatives.

Oleophobic treatment can be used, for example fluorinated silanes, fluorinated siloxanes, fluorocarbon compounds or fluorinated silicones.

According to the invention, the hydrophobizing agents are expedient in quantities of 0.5 to 10%, based on the basis weight of paper or paper-like material.

For hydrophobing and / or oleophobization, both Use of water-based systems, for example in the form of emulsions or dispersions, as well as the use of Systems based on organic solvents possible.

In a preferred embodiment of the present invention hydro- and / or oleophobicizing agents are used, which according to are manufactured and work using the sol / gel process. this has the special advantage of wafer-thin glazing of the surface of the paper or paper-like material, so that on the one hand guarantees the integration of the particles used as well as a high moisture stability can be achieved. So can in a preferred embodiment when using Silanes, siloxanes or silicones as hydro and optionally Oleophobic agents in sufficient amounts for an additional The use of binders can be dispensed with.

In a further preferred embodiment of the present Invention leaves a hydrophobicity of paper or paper-like Material still improve by adding hydrophobic fibers the production of the paper according to the invention or paper-like Materials are used.

Optionally, chromium, aluminum or zirconium salts can also be used in addition to the improvement of the hydrophobizing effect also Fixation of the particles to the fibers can also be used.

All hydro and / or are favorable for certain applications Oleophobic agents which bind substantively to the matrix and therefore have no migration behavior or do not evaporate or can otherwise change such as fluorinated and non-fluorinated silanes and fluorinated and non-fluorinated siloxanes. With regard to the application, such hydro- and / or Oleophobiermittel used, which solvent content of less than 10% included.

In a preferred embodiment is also within the scope of inventive method in addition to using a Hydrophobing agent and optionally oleophobicizing agent a further downstream hydro- and / or oleophobicization carried out. It is important to ensure that you are already trained Surface structures are not impaired or destroyed become. The downstream hydro- and / or oleophobicization should therefore only have a few molecular layers of coating material include. For this reason, spraying and printing processes effective alternatives to diving procedures or Size press application process.

In a further preferred embodiment, the paper or paper according to the invention paper-like material initially printed in an intermediate step, before it is hydro- and / or oleophobic as described above is equipped. The hydro- and / or oleophobicizing can, for example, in the printing press after the actual printing or a Pre-hydrophobic material can be printed with hydrophobic inks and then a residual hydrophobization with fluorinated Get silanes or fluorinated siloxanes.

The achievement of the strongly anti-adhesive behavior is at uncoated and coated papers possible, in addition for all paper-like materials, cardboard boxes and cardboard boxes as well as metallized papers. The equipment leads to strong water, oil and dirt repellency, which has proven to be anti-adhesive Effect articulated. This can be in a wide variety Applications, for example release papers, packaging papers For example, for frozen goods, posters or other liquid-repellent Papers that are exposed to environmental influences, be used.

Examples:

1. An overlay paper (25 g / m ² ) produced on an inclined screen machine is immersed in a bath of the hydrophobizing agent Antispread® for 5-10 s and then air-dried for 10-30 s. The paper then shows a contact angle of approximately 140 ° and is largely non-wettable.

2. A filter wrapping paper (FU-NP24 smooth), 24 g / m ² with a filler content of 17-18% and an average particle size of 2 µm is sputtered with gold and then hydrophobized with Antispread®. The measured contact angle is approx. 140 °. There are big differences between the screen and the top. The side with good microstructuring is the screen side, which shows a very low hysteresis. To a large extent, it is not wettable.

3. A paper produced on a Fourdrinier machine with a basis weight of 29 g / m ² with a calcium carbonate content of 30% and an average particle size of 2 µm is gold-sputtered and hydrophobized according to Example 2 and shows contact angles between 130 and 140 ° with almost undetectable hysteresis. Drops run off the surface immediately, even at small angles.

4. A paper made from 70% hardwood pulp and 30% softwood pulp with a calcium carbonate content of 33% with medium Particle size of 2 μm, which is made hydrophobic according to Example 2, shows contact angle over 155 ° with undetectable hysteresis between the advancing and retreating angles. Pearl drops of water at the smallest tilt angles, even after a long touch from.

5. A paper made of 70% hardwood pulp and 30% softwood pulp with an SiO ₂ filler content of 50% with an average particle size of 3 µm, which was hydro- and oleophobic with Dynasylan VPS 8815, shows a contact angle greater than 145 ° and a progression and retreat angle less than 10 ° and moisture resistance of over 30 minutes.

6. A paper made from 70% hardwood pulp and 30% softwood pulp with an SiO ₂ filler content of 20% with an average particle size of 3 µm, half of which was introduced into or via the size press together with the hydrophobizing agent Dynasylan VPS 8815 , shows a contact angle greater than 145 ° and a progression and retreat angle less than 10 ° and a moisture penetration stability of over 30 minutes.

Claims (15)

Microstructured paper or paper-like material with self-cleaning and anti-adhesive effect, which has elevations and depressions on the surface, the distance between the elevations being in the range from 0.04 to 100 μm and the height of the elevations in the range from 0.04 to 100 μm , wherein the paper or paper-like material is characterized in that it contains particles of a particle size of 0.04 to 50 µm bound to the paper or paper-like material and wherein the paper or paper-like material is hydrophobic over the entire material cross section. Paper or paper-like material with anti-adhesive Effect according to claim 1, wherein the paper or paper-like material is also oleophobic. Paper or paper-like material according to claim 1 or 2, the paper or paper-like material one Has contact angle with water greater than 120 °. Process for the production of a microstructured paper or paper-like material with self-cleaning and / or anti-adhesive effect that is hydrophobic over the entire material cross-section and has elevations and depressions on the surface, the distance between the elevations being in the range of 0.04 to 100 μm and the The height of the elevations is in the range from 0.04 to 100 µm, characterized in that , with the use of a hydrophobizing agent in the course of a wet laying process, particles of a particle size of 0.04 to 50 µm are added to the fibers of the paper or paper-like material and the particles on these fibers be fixed with a binder. Process for making paper or paper-like The material of claim 4, wherein the fibers are Cellulose fibers. Method according to one of claims 4 or 5, wherein the fibers used plastic fibers made of polypropylene (PP), Polyvinyl acetate, polyethylene (PE) and / or polylactic acid (PLA). Method according to one of claims 4 to 6, wherein the Particles in an amount of 5 to 65%, based on the Basis weight of the paper or paper-like material, be added. Method according to one of claims 4 to 7, wherein an oleophobicizing agent is additionally used. Method according to one of claims 4 to 8, wherein it is in the hydro- and / or oleophobicizing agent by one after agent produced by the sol / gel process. Method according to one of claims 4 to 9, wherein in addition to using a hydro and optionally another oil repellent downstream hydro- and / or oleophobicization carried out becomes. Method according to one of claims 4 to 10, wherein the particles are selected from inorganic compounds such as metal oxides, corundum, silicon dioxide, quartz, quartz powder, silica sols, TiO ₂ , carbonates and sulfates, kaolin or talc. Method according to one of claims 4 to 11, wherein the Binder made of latex, acrylate and / or Styrene binders and / or fluorinated and not fluorinated silanes, fluorinated and non-fluorinated Siloxanes and / or functionalized and not functionalized silicone oils are selected. Method according to one of claims 4 to 12, the additionally the step of printing on one microstructured side of the paper includes. The method of claim 13, wherein the printing is prior hydrophobization or oleophobization or combined hydro- and oleophobicization of the paper or paper-like material. Use paper or paper-like material according to claim 1, 2 or 3 as release paper, Packaging paper or packaging cardboard, posters or other liquid-repellent papers or paper-like ones Materials that are exposed to environmental influences, for example.