CN101389727B - Method for treating a substrate - Google Patents

Abstract

A method for processing a substrate is described. According to one aspect, the method includes applying a polymer coating to the substrate; and contacting the polymer coating with a heated surface while the coating is still wet. Optionally, the polymer coating may comprise a crosslinkable material, and a crosslinking agent may be used to promote crosslinking. The polymer coating replicates the heated surface. Products produced according to the method are also disclosed. The products are characterized by having surface voids within the coating.

Description

method of processing the substrate

Related application reference

This application claims the benefit of priority under 35 U.S.C. § 119(e) of Provisional Application Serial No. 60/776,114, filed February 23, 2006, which is incorporated herein by reference in its entirety. the

Background of the invention

The present disclosure relates to methods of treating substrates with polymeric film-forming compositions. More specifically, the present disclosure relates to a method of making paper or paperboard comprising the steps of applying a polymeric film-forming coating to a substrate, and contacting the polymeric coating to a heated surface while the polymeric coating is still wet. The resulting polymer layer has a smooth surface with voids (eg air bubbles) just below the surface. In some embodiments, the polymeric coating can comprise a crosslinkable hydrogel, and a crosslinking solution can be applied to the polymeric coating on the surface of the substrate, thereby forming an at least partially crosslinked polymeric coating, which is then contacted with heat surface contact. The present disclosure also relates to processed substrate products. the

Paper is made by a substantially continuous process in which a dilute aqueous slurry of cellulosic fibers is fed into the wet end of the paper machine and a consolidated dry web of indefinite length emerges continuously from the dry end of the paper machine. The wet end of a paper machine consists of one or more headboxes, a drainage section and an extrusion section. The dry end of a modern paper machine consists of a number of steam heated rotating shell cylinders distributed along a curved web travel path under a heat limiting hood structure. Although there are a large number of design variants for each of these paper machine sections, the most commercially important variant is the fourdrinier paper machine, in which the headbox discharges a wide stream of stock onto a moving screen with extremely fine mesh openings. the

Screens are constructed and driven as endless belts carried on a multitude of support rollers or foils. The pressure differential across the screen from the side contacting the slurry to the opposite side draws water from the slurry through the screen while this section of the screen travels along the table portion of the screen line loop, as the slurry dilution water is extracted, so the fiber components of the slurry as wet But a substantially consolidated mat collects on the screen surface. When the end of the screen loop table length is reached, the mat has gathered sufficient mass and tensile strength to achieve a short physical gap between the screen and the first press roll. The first press roll carries the mat into a first squeeze nip where the major volume of water remaining in the mat is removed by nip pressing. This may be followed by one or more additional nips. the

The mat continuum from the extrusion section, which now generally exhibits the characteristics of a wire, enters the drying section of the paper machine where the remaining water is removed thermodynamically. the

In general, the most important fibers for papermaking are obtained from softwood and hardwood species. However, fibers derived from straw or bagasse have been used in some cases. Both chemical and mechanical defibration processes well known in the art have been used to separate papermaking fibers from naturally occurring compositions. Papermaking fibers obtained by chemical defibration processes and methods are generally referred to as chemical pulp, while papermaking fibers obtained by mechanical defibration methods may be referred to as groundwood pulp or mechanical pulp. There are also combined defibration processes such as semi-chemical, thermochemical or thermomechanical processes. Any of the tree species can be defibrated by chemical or mechanical means. However, some species and defibrillation processes are a better economic or functional match than others. the

An important difference between chemical and mechanical pulp is that mechanical pulp can be fed directly to the paper machine from the defibration stage. On the other hand, chemical pulp must be mechanically defibrated, washed and screened at least after chemical cooking. Typically, chemical pulp is also mechanically refined after screening and before the paper machine. In addition, the average fiber length of mechanical pulp is generally shorter than that of chemical pulp. However, fiber length is also highly dependent on the wood species from which the fibers originate. Softwood fibers are usually about 3 times longer than hardwood fibers. the

The final properties of a particular paper are largely determined by the type of stock used and the manner in which these stock are handled by the paper machine and web-forming process. Important operating elements in the apparatus for forming the paper web are the headbox and the screen. the

Coated paper or paperboard for printing and for packaging are generally required to have high gloss levels, excellent smoothness and excellent printability as well as certain strength and stiffness characteristics. the

If the coated paper or paperboard has a high stiffness, it can run smoothly through a high speed printing or packaging machine with less feed jams. Higher stiffness paper can be advantageously used in books, magazines, and catalogs because it provides a stiffness or heaviness similar to a hardcover book. For packaging, high stiffness is necessary to maintain the structural integrity of the paperboard product during filling and subsequent use. the

Stiffness is closely related to the basis weight and density of the paper. The general trend is that stiffness increases with increasing basis weight and decreases with increasing paper density. Stiffness and other properties can be improved by increasing the basis weight. However, this would result in a product utilizing more fibers, which increases cost and weight. Therefore, there is a need for coated paper or paperboard with high stiffness but medium basis weight. Papers with a medium basis weight are also more economical because less raw material (fiber) is used. Additionally, shipping costs based on weight are less for low basis weight papers. the

In addition to high stiffness, high gloss and smoothness are often required of the coated paper or board which has to be printed. For coated paper or paperboard to have such quality properties, it is generally necessary to increase the density to a certain extent to allow a usable printing surface. Smoothness is usually achieved by calendering. However, calendering results in a reduction in thickness, which generally results in a corresponding decrease in stiffness. The calendering process destroys stiffness by significantly reducing thickness and increasing density. Conventional coated board grade base sheets are typically heavily densified by calendering to provide a surface roughness low enough to produce an industrially acceptable final coating smoothness. These calendering processes, including wet stacking, can increase density by as much as 20%-25%. the

Thus, for a given number of fibers per unit area, the relationships between gloss and stiffness and between smoothness and stiffness are generally inversely proportional to each other. Packaging grades are sold based on paper caliper, so a manufacturing process that reduces caliper (increases board density) lowers the selling price. A process that results in less thickness drop saves material cost. Thickness is measured in "points", where point = 0.001 inches. For example, conventional methods of making 10 point board require the use of board with a pre-calender caliper greater than 12 point. It is desirable to be able to produce a finished paperboard of approximately the same thickness as the initial backing. the

Modifications of the calendering process including moisture gradient calendering, thermal calendering, soft calendering, and tape calendering slightly increased the stiffness for a given thickness, but did not change the fundamental ratio between thickness, stiffness, smoothness, and printing properties. the

Various proposals have been made to improve the stiffness of coated paper or board for printing without calendering. For example, several proposals include high cork content in the raw material, the addition of specially designed fibers to the raw material, the addition of highly branched polymers to the raw material, and high amounts of glass transition temperature (often referred to as "Tg") high Starch or copolymer latex. the

However, a potential drawback of these stiffness improving methods is that although they are effective in increasing paper stiffness, they may reduce the smoothness, gloss and/or printability of the resulting coated paper. the

For the above reasons, it is very difficult to obtain satisfactory paper smoothness without increasing the density. Other methods can be used to vary the density/smoothness relationship in paper and board grades. Applying a paper coating is a very common method of enhancing the surface properties of paper without causing a dramatic increase in paper density which is generally related to the level of calendering required to obtain a certain level of smoothness. Preferably, the final coated surface should be uniform to provide acceptable appearance and printing properties. the

Therefore, it is desirable to provide paper or paperboard products having desirable properties while maintaining the original density of the sheet or minimizing density increase. Additionally, it would be desirable to provide paper or paperboard that exhibits improved smoothness without the concomitant increase in density associated with conventional methods of forming smoothness. There are cast coating processes that produce very smooth surfaces, but these processes generally operate at slower production speeds than many paper machine speeds. the

public overview

In one embodiment, an article is disclosed that includes a substrate with a coating on the substrate. The coating includes a water soluble polymer and a release agent. There are voids formed within the coating. the

In another embodiment, an article is disclosed that includes a substrate with a coating on the substrate. The coating includes water soluble polymers and is substantially free of elastomeric materials. There are voids formed within the coating. the

In another embodiment, an article is disclosed that includes a substrate with a coating on the substrate. The coating includes a surface, and the surface has a Sheffield smoothness of less than about 300 units. There are voids formed below the surface of the coating. the

In another embodiment, an article is disclosed that includes a substrate with a coating on the substrate. The coating includes a water soluble polymer, a release agent and substantially no elastomeric material. The coating includes a surface, and the surface has a Sheffield smoothness of less than about 300 units. There are voids formed below the surface of the coating. the

In another embodiment, a method of processing a substrate is disclosed. A wet film of the aqueous polymer solution is applied to the substrate. The aqueous polymer solution is immobilized by contacting the aqueous polymer solution with a heated surface causing the aqueous polymer solution to boil and at least partially drying the aqueous polymer solution. the

In another embodiment, a method of processing a substrate is disclosed. A wet film of the aqueous polymer solution is applied to the substrate. The aqueous polymer solution is immobilized by contacting the aqueous polymer solution with a heated surface causing the aqueous polymer solution to boil and form voids that remain in the aqueous polymer solution and at least partially dry the aqueous polymer solution. the

In another embodiment, a method of processing a substrate is disclosed. The coating of the aqueous polymer solution is applied to the substrate as a wet film. The coating includes a water soluble polymer and a release agent. The membrane is fixed by contacting the membrane with a heated surface having a temperature greater than about 150° C. for less than about 3 seconds to cause the aqueous polymer solution to boil and form voids in the membrane and at least partially dry the membrane. the

In another embodiment, a method of processing a substrate is disclosed. The coating of the aqueous polymer solution is applied to the substrate as a wet film. The coating includes a water soluble polymer and is substantially free of elastomeric material. The membrane is fixed by contacting the membrane with a heated surface having a temperature greater than about 150° C. for less than about 3 seconds to cause the aqueous polymer solution to boil and form voids in the membrane and at least partially dry the membrane. the

In another embodiment, a method of processing a substrate is disclosed. The coating of the aqueous polymer solution is applied to the substrate as a wet film. The coating includes a water soluble polymer and is substantially free of elastomeric materials. The membrane is fixed by contacting the membrane with a heated surface having a temperature greater than about 150° C. for less than about 3 seconds to cause the aqueous polymer solution to boil and form voids in the membrane and at least partially dry the membrane. The dried coating surface has a Sheffield smoothness of less than about 300 units. the

In another embodiment, a method of processing a substrate is disclosed. The coating of the aqueous polymer solution is applied to the substrate as a wet film. The coating includes a water soluble polymer, a release agent and essentially no elastomeric material. The membrane is fixed by contacting the membrane with a heated surface having a temperature greater than about 150° C. for less than about 3 seconds to cause the aqueous polymer solution to boil and form voids in the membrane and at least partially dry the membrane. The dried coating surface has a Sheffield smoothness of less than about 300 units. the

In another embodiment, a method of treating a cellulosic substrate is disclosed. A wet film of the aqueous polymer solution is applied to the substrate. The aqueous polymer solution includes at least about 60% by dry weight of a water-soluble polymer and up to 10% by dry weight of a release agent. The aqueous polymer solution is immobilized by contacting the aqueous polymer solution with a heated surface having a temperature greater than about 150°C for less than about 3 seconds to cause the aqueous polymer solution to boil and form voids in the aqueous polymer solution and to at least partially dry the aqueous polymer solution. the

Brief description of the drawings

Figure 1 is a schematic diagram of an apparatus for treating a substrate with a polymer coating according to one embodiment of the present invention. the

2-9 are cross-sectional views showing the topography of samples prepared according to one embodiment of the present invention and having a topcoat. the

10-12 are cross-sectional photographs showing the morphology of samples prepared according to one embodiment of the present invention. the

13-14 are surface photographs obtained with a scanning electron microscope showing the morphology of samples prepared according to one embodiment of the present invention.

15-16 are surface photographs obtained with a backscatter scanning electron microscope showing the morphology of samples prepared according to one embodiment of the present invention. the

Figure 17 is a graph showing the size distribution of voids in samples prepared according to one embodiment of the present invention. the

Detailed description of the invention

In describing the preferred embodiments, certain technical terms will be used for the sake of clarity. It is intended that such technical terms include not only the mentioned embodiments but also all technical equivalents employed in a similar manner, for a similar purpose, to a similar effect. Citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. All weights, percentages and ratios are by weight unless otherwise indicated or unless the context suggests otherwise. the

The present disclosure relates to methods of treating substrates with polymeric film-forming coatings. More specifically, the present disclosure relates to a method of making paper or paperboard comprising the steps of applying a polymeric coating to a substrate, and contacting the polymeric coating to a heated surface while the polymeric coating is still in a wet state. The boiling of water in the polymer coating causes voids to form beneath the surface, while the surface of the film is smooth. Paper or paperboard produced according to some embodiments of the present invention exhibits desirable levels of surface flatness and smoothness without significant densification of the base paper. In some embodiments, the polymeric coating can include a crosslinkable material, and a crosslinking solution can be applied to the polymeric coating on the surface of the substrate to form an at least partially crosslinked polymeric film-forming composition. In this case, the polymeric coating can generally be applied to the paper web first, and then the crosslinking solution can be applied before the processed paper web comes into contact with the heated surface. For weakly crosslinked polymers, the crosslinking solution can be provided in the coating itself. the

One advantage of treating substrates with polymeric film-forming coatings in accordance with the present invention relates to the increased smoothness and/or planarity that can be obtained without significantly increasing the density of the flakes or reducing the thickness of the flakes. The heavy calendering of cellulosic webs associated with conventional techniques is not required to produce papers with printing properties comparable to conventional coated papers. In addition, even when the cellulosic web is smoothed, only much lower pressure can be applied to provide print-like properties on the increased stiffness paper. According to some embodiments of the present invention, planarizing the cellulosic web results in a reduction in caliper of no more than about 7%, typically between about 2% and 5%. In comparison, conventional coated papers are typically calendered prior to coating at much higher pressures, which results in a density increase of about 20-25%. According to one aspect of the invention, the cellulosic web may be calendered to a Parker Print Surf smoothness of between about 2 and 6 microns prior to application of the polymeric film. However, substrates with higher Parker Print Surf values can be used. For example, a substrate with a Parker Print Surf smoothness of about 9 microns can be used. Determination of Parker Print Surf smoothness according to TAPPI standard T 555 om-9. the

Figure 1 illustrates an apparatus 10 for practicing some embodiments of the invention. The substrate 12 is treated on one surface with a cross-linkable polymer coating 14 to form a polymer coating layer 16 on the substrate 12 . While the polymer coating is still wet, an optional crosslinking solution 18 may be applied to the polymer coating layer 16 thereby forming a crosslinked polymer coating 20 on the substrate 12 . Polymer coating 20 is generally at least partially crosslinked. The polymer coating is still in a wet state prior to contacting the hot polishing drum 22 by pressing the web 12 against the drum surface with press rolls 24. The heat from the drum surface causes internal boiling of the wet polymer coating, creating voids in the polymer below the surface. The crosslinking solution crosslinks and gels the polymer coating into a substantially continuous layer or film. Typically, the resulting film will exhibit increased strength over the substrate. The polymer treated sheet may not be sufficiently dried so it may be conveyed through the second heater 26 . Any type of secondary heating device capable of drying the processed flakes without negatively affecting the flake properties can be used. The processed sheet emerges from the second heater 26 as a polymer film processed substrate 28 characterized by enhanced planarity and smoothness. Optionally, additional coating process 30 (and other processes such as coating, gloss calendering, etc.) may be used to form coated product 32 . the

As shown in FIG. 1 , the web wraps around a substantial portion of the hot polishing drum 22 . The number of wraps may depend on operating conditions such as web speed, moisture content of the polymeric film forming composition 20, drum temperature, and other process factors. It is also possible that a small amount of contact time with the hot polishing drum 22 may be sufficient. In addition to providing the substrate in web form, it can also be provided in sheet form. the

Crosslinkable polymer coatings and optionally crosslinking solutions can be applied by numerous techniques such as dip coating, rod coating, knife coating, gravure roll coating, reverse roll coating, metered size press, smooth roll coating, extrusion coating , curtain coating, spraying, etc. The crosslinkable polymer coating and the crosslinking solution can be applied by the same application technique, or different methods can be used for each. the

One embodiment according to the invention is based on the coagulation or gelation that takes place between polyvinyl alcohol and borax. According to this system, polyvinyl alcohol (PVOH) is an example of a crosslinkable polymer and a borax solution is an example of a corresponding crosslinker. Once the PVOH solution 14 is applied, at about 25% solids and about 5 g/ ^m dry coverage, the crosslinker solution 16 is applied at a rate and solution solids that provide at least about 0.1 g/ ^m dry borax coverage. This wet crosslinked polymer film 20 is then brought into contact with a hot polishing drum 22 by pressing the web 12 against the drum surface with press rolls 24 . The drum surface temperature is at least about 150°C, or according to some embodiments, at least about 190°C, so that the coating can dry and come off the drum surface. The contact time of the polymer film with the drum may be in the range of no more than about 3.0 seconds, more particularly between about 0.5-2.0 seconds. This is sufficient time for the polymer film to set and solidify, giving the polymer film surface a smooth finish that mirrors the drum surface. Fixing the polymeric film includes at least partially drying the film. When the coating leaves the drum, it is not necessarily fully dry and secondary drying 26 may be required. The web then continues through the process and may receive additional coating layers, such as conventional coatings, before being taken up. The polymer coating can be applied as a single layer or as two or more layers. Limited experimentation has also shown that it is possible to immobilize or coagulate polymer films using only momentary exposure to a heated drum, which can be achieved by pressing the web 12 against the heated drum 22 using press rolls 24, without requiring the web to rotate around the heat. Any additional wrapping of the barrel. However, it is contemplated that some wrapping of the heated drum may be implemented, and optionally a felt 23 may be used to help squeeze the web into contact with the heated drum. The felt 23 may be carried between the press roll 24 and the heated drum 22 if it is used to help press the web into contact with the heated drum.

Contact between the polymer film and the heated drum causes boiling to occur in the polymer film, forming voids or air bubbles in the film. The nip conditions should be adjusted so that boiling can occur. Satisfactory laboratory results have been obtained using resilient press rolls, 9" wide paper webs, and nip loads between about 2 and about 15 pounds per linear inch. Depending on the press roll hardness and the diameter of the heated drum and press roll, it may Conditions must be adjusted.

Specific examples of crosslinkable polymers useful in some embodiments of the present invention include crosslinkable hydrogels. The following crosslinkable hydrogels are especially useful: starch, waxy corn, protein, polyvinyl alcohol, casein, gelatin, soy protein, and alginate. One or more polymers selected from the above may be used. Crosslinkable polymers are generally applied in solution, usually as an aqueous solution. The concentration of the polymer in the solution is not particularly limited, but can be readily determined by one of ordinary skill in the art. For example, a solution of about 20% starch may be used, as described below. The crosslinkable polymer may be applied to provide a surface coverage (dry basis) of from about 3 to about 15 gsm (g/ ^m2 ), more specifically from about 4 to about 8 gsm. According to particular embodiments of the present invention, the crosslinkable polymer may be used in an amount of from about 60% to about 100% by weight of the dry material.

Specific examples of crosslinking agents include borates, aldehydes, ammonium salts, calcium compounds, and derivatives thereof. If used, the crosslinking agent can generally be applied in solution, usually as an aqueous solution. The concentration of the cross-linking agent in the solution is not particularly limited, but can be readily determined by one of ordinary skill in the art. The crosslinker may be applied to provide a surface coverage (dry basis) of from about 0.1 to about 0.5 gsm, more specifically from about 0.2 to about 0.3 gsm. the

The temperature of the heated surface exceeds that normally used for cast coating. Higher temperatures should allow higher operating speeds. It is contemplated that paper or paperboard produced according to some embodiments of the present invention may be produced at speeds of about 750 to 3000 fpm, more particularly about 1500 to 1800 fpm. While not wishing to be bound by theory, the choice of higher temperature and residence time causes the coating composition to be heated to its boiling temperature and it appears that the contact area between the coating and the drum increases as the coating boils. The increased contact produces a polymer film heated surface that exhibits increased smoothness and gloss. Additionally, the treated surface is ink receptive. The boiling of the paint as it is planarized on the polishing drum surface appears to significantly improve the gloss and smoothness of the final polymer film-treated substrate. the

Polymer coatings on a substrate are generally extruded against a heated surface for sufficient time to allow the coating to boil and then set to a smooth, glossy finish. According to specific embodiments, the contact time of the forming polymer film onto the drum is in the range of no more than about 3.0 seconds, more specifically no more than about 2.0 seconds, most especially no more than about 0.5 seconds. the

The polymer coating may also include one or more pigments. Examples of useful pigments include, but are not limited to, kaolin, talc, calcium carbonate, calcium acetate, titanium dioxide, clay, zinc oxide, aluminum oxide, aluminum hydroxide, and synthetic silicas such as amorphous silica, amorphous silica, or Finely divided silica is an example thereof. Organic pigments can also be used. the

The crosslinkable polymer coating and/or crosslinking solution may also include one or more release agents. Specific examples of release agents useful herein include, but are not limited to, waxes such as petroleum, vegetable, animal and synthetic waxes, fatty acid metal soaps such as metal stearates, long chain alkyl derivatives such as fatty esters, fatty amides, fatty acids Amines, fatty acids and fatty alcohols, polymers such as polyolefins, silicone polymers, fluoropolymers and natural polymers, fluorinated compounds such as fluorinated fatty acids, and combinations thereof. One of ordinary skill in the art can readily determine the amount of release agent to use in a particular application. Typically, the coating may contain about 0.3-10% release agent, more particularly about 2-5% by weight. Instead of or in addition to the release agent in the paint, the release agent can also be sprayed onto the paint surface, or applied to the heated drum surface. If a non-tacky surface can be provided on the heated drum, whether by release agent or other means, it may not be necessary to apply a release agent in the coating or to the surface of the coating. the

The polymeric coatings used in some embodiments of the present invention, comprising at least the polymers described above, are generally prepared in the form of aqueous compositions. The appropriate ratio among these components varies depending on the polymer composition, application conditions, etc., but is not particularly limited as long as the produced treated paper can satisfy the quality required for its intended use. In addition, polymer coatings according to some embodiments of the present invention may optionally contain additives such as dispersants, water retaining agents, thickeners, defoamers, preservatives, colorants, water repellents, wetting agents, desiccants , initiators, plasticizers, fluorescent dyes, UV absorbers, release agents, lubricants and cationic polyelectrolytes. the

According to a particular embodiment of the present invention, the substrate is treated with a polymeric coating in an area close to the center of the paper machine, such as at the size press. Additionally, the means for applying the polymeric coating to the substrate can be positioned relative to the paper machine to apply the polymeric film on either surface of the forming web. More than one device can be used to apply the polymeric film to each side of the forming web. the

These advantages allow the use of lightly calendered paper or board, thus retaining stiffness while providing good printing properties. the

The substrate is generally formed from fibers commonly used for such purposes, including unbleached or bleached kraft pulp, according to particular embodiments. Pulp can consist of hardwood or softwood or combinations thereof. The cellulosic fiber layer may have a basis weight of from about 30 to about 500 gsm, more specifically from about 150 to about 350 gsm. The substrate may also contain organic and inorganic additives, sizing agents, retention agents and other adjuvants known in the art. The final paper product may comprise one or more layers of cellulosic fibers, polymeric film layers, and, according to some embodiments, also other functional layers. the

According to some embodiments, the present invention provides one- or two-sided coated printing or packaging paper or paperboard, its Parker Print Surf smoothness values are about 2-3 microns lower. the

The paper or paperboard described herein may also be provided with one or more other coatings. A topcoat comprising conventional components can be provided to enhance certain properties of the paper or board. Examples of such conventional components include pigments, binders, fillers and other specialized additives. When present, topcoats can be applied at much lower coat weights than conventional coatings and provide print-like properties. Thus, the top coat weight may be about 4-9 gsm as a single coat of paint, or about 8-18 gsm as two coats of paint. In contrast, conventional coated paper typically requires about 10-20 gsm (as a single coating layer) or 18-30 gsm (as two coating layers) to provide comparable surface properties. Paper or cardboard can also be coated on the side of the sheet that has the untreated surface. the

Having given the teaching of the disclosure, it will now be illustrated by means of specific examples, which should in no way be construed as limiting the scope of the claims. the

According to some embodiments of the present invention, substrates having a thickness of about 10 points, a Parker PrintSurf (PPS) value of about 9 microns (using a soft backing, 10 kg pressure) and a Sheffield smoothness of about 310 can be processed, resulting in improved Handled sheets with smoothness and only minimal thickness reduction. The substrate may be treated by applying a PVOH solution of approximately 25% solids to the substrate to provide a ^dry coverage of approximately 5 g/m2. The crosslinker solution is then applied at a rate and solution solids content to provide at least about 0.1 g/ ^m dry borax coverage. The wet crosslinked polymer film is brought into contact with the hot polishing drum by pressing the sheet against the drum surface. The drum surface temperature may be at least about 190°C. The paint will dry and come off the drum surface. The contact time of the polymer film with the drum will generally be in the range of between about 0.5-2.0 seconds. The processed sheet will have a thickness between about 9.6 and 10.0 points, a PPS value of about 2.4-3.0, and a Sheffield smoothness of about 140-170.

In a preferred embodiment, a starch solution may be used as the polymer material in the polymer coating. the

One aspect of the present disclosure relates to a paper or paperboard manufacturing method. According to one embodiment of the invention, the method comprises applying a polymeric coating comprising a crosslinkable hydrogel to a substrate, applying a crosslinking solution to the polymeric coating on the surface of the substrate, thereby forming an at least partially crosslinked polymeric film-forming coating and contacting the polymeric film-forming coating to the heated surface while the polymeric film-forming coating is still wet. The heated surface can be a hot polished drum with a flat smooth finish. The temperature of the heated surface generally ranges from about 150°C to about 240°C. Higher temperatures may be used, for example up to about 300°C. According to some embodiments, the temperature of the heated surface is in the range of 180°C to about 200°C, and according to some embodiments, is at least about 190°C. the

According to a particular embodiment of the invention, the crosslinkable polymer may be selected from starch, waxy corn, protein, polyvinyl alcohol, casein, gelatin, soy protein and alginate. According to some aspects of the invention, the crosslinkable polymer may be used in an amount of about 60 wt% to about 100 wt% of the dry material. the

In some manifestations, the crosslinking agent may be a borate or a borate derivative such as borax, sodium tetraborate, boric acid, phenylboronic acid, or butylboronic acid. The crosslinking agent can be used in an amount of from about 1% to about 12%, based on the crosslinkable polymer. the

The invention also relates to treated paper produced according to the methods described herein. The treated paper is characterized by improved smoothness and a relatively small increase in density compared to the original sheet. the

Since it is desirable to keep the paint wet when it contacts the heated drum, the paint can be humidified, for example, by adding water. One method is to spray water onto the paint before it touches the heated drum. However, in some embodiments it is also possible to operate without any additional humidification. the

In some embodiments, starch can be used as the soluble polymer. In some embodiments, starch-based coatings can be run successfully without crosslinkers and can give good results without gelling (also known as setting). the

The starch solution containing 2-5% release agent was contacted to the heated drum under the above conditions. Under some conditions, water alone can be used as a spray and produce a good reproduction of the polished surface if it is desired to moisten the paint. If the coating solids are low enough, it can be operated without water spray humidification. A 20% solids starch coating was applied to the web and exposed to a heated drum with good reproduction. the

Starch coatings with 25% and 30% solids content were also tested. Both coatings came off the drum without any tack, but without good surface reproduction. The 25% solids paint was moderately reproduced, but the 30% solids paint was not very smooth. It appears that the presence of a certain amount of water at the surface helps transfer boiling throughout the paint. Below a certain amount of surface water, local surface areas may still have sufficient boiling to provide a good reproduction of the bowl surface, but other surface areas may not. Thus, when wetting the surface without a water spray, the percentage of area that reproduces a smooth drum surface decreases with increasing paint solids as the solids increase beyond 20%, until at about 30% paint solids, little Or surface smoothness reproduction cannot be obtained. Complete surface reproduction can be obtained if sufficient water is sprayed on the surface of the 30% solids coating prior to exposure to the heated drum. We would expect this relationship to also be influenced by raw material absorbency, paint volume, paint viscosity and process speed. It should be possible to determine the effect of these parameters by further experiments. the

The above example was run with a chrome surface on a heated drum. The examples described below were run after resurfacing the drum with a tungsten carbide coating. In each of these examples, several "runs" were performed to collect data. The run consists of the drum being heated to about 190°C, the spray level set, the coating applied to the web by the metering rod method, followed by an optional moist spray (which optionally contains a crosslinker) , and then contact the web with the drum at 35 fpm. The drum temperature during the run was varied between 180°C and 190°C. During operation, the only variable that is changed is the amount of paint applied by the metering rod. Changes in paint type, paint solids, or spray level were made in different experimental runs on the plant. Paint loads are measured by differential weight and reported as dry through. Run some experiments with crosslinkers in the coating itself, for example when using materials that do not crosslink strongly such as starch. the

Example 1

A minimally extruded substrate with a basis weight of 111 lb/3000 ^ft2 was used as a substrate for applying and handling a simple coating composition. The first coating was 95% dry weight CELVOL 203 S polyvinyl alcohol (PVOH) and 5% Emtal 50 VCS using triglycerides as release agents. The paint solids content was 20% by weight. Coatings are applied by metering rod. Table is a list of samples and test conditions. Sample 1.1 was prepared by spraying the paint with a crosslinking solution comprising 3 wt% borax and 1 wt% sulphonated castor oil as release agent. The spray rate was 48 ml/min. The sample replicated the bowl well and released from the bowl without sticking. Significant improvements in smoothness are obtained with minimal thickness loss. For sample 1.2, the conditions were the same except that borax was not used in the spray solution. Without the borax to crosslink the polyvinyl alcohol, the paint could not come off the surface and some of the film remained on the drum surface. This experiment clearly shows the benefit of crosslinking polyvinyl alcohol.

surface

                      Samples and Test Conditions 

                                                   

In another run, carboxymethylcellulose (CMC) was substituted for polyvinyl alcohol to compare polymer properties. Carboxymethyl cellulose is FINFIXX 30 which will only work at 7% solids due to paint viscosity. Coatings were formulated with 95% polymer and 5% Emtal. Samples 1.3 and 1.4 are two different coat weights sprayed with borax spray 48ml/min. The paint replicates the drum surface well and comes off the drum completely. Smoothness was improved with minimal thickness loss, but the smoothness was not as good as with polyvinyl alcohol. For the run that produced sample 1.5, no borax was used in the spray. The paint replicates the drum surface well and comes off the drum completely. Smoothness is improved by removing borax. This shows that uncrosslinked coatings can replicate and come off the drum, which means that materials other than crosslinkable materials can be used in this method. the

Example 2

A minimally extruded substrate with a basis weight of 111 lb/3000 ^ft2 was used as the substrate on which the simple coating composition was applied and handled. The first coating was 95% dry weight CLEER-COTE 625 starch (viscosity modified waxy corn starch) and 5% Emtal 50 VCS using triglyceride as a release agent. The paint solids content was 20% by weight. Coatings are applied by metering rod. Sample 2.1 was prepared by spraying the paint with a crosslinking solution comprising 3 wt% borax and 1 wt% sulfonated castor oil as release agent. The spray rate was 46 ml/min. The sample replicated the bowl well and released from the bowl without sticking. Significant improvements in smoothness are obtained with minimal thickness loss. Samples 2.2, 2.3, 2.4 and 2.5 were prepared using different coat weights of the same paint, but the spray did not contain borax. All samples replicated the drum well and completely detached from the drum. Samples 2.6 and 2.7 were performed without any spray at all. The sample replicated the drum well and came off completely. The smoothness values are not as good, but the samples still have significantly improved smoothness at minimal thickness reduction. This shows that the method works without any humidification spray.

Example 3

This experiment was a continuation of Example 2, exploring the effect of coating solids content. Samples 3.1 and 3.2 were run at 23% coating solids without any humidifying spray. Get well copied and released. For samples 3.3 and 3.4, the coating solids content was increased to 25.7%, again applied without a humidifying spray. Get full release, but get incomplete surface replication. Based on visual observation, only about 90-95% of the surface replicated the tumbler. For samples 3.5 and 3.6, this same 25.7% solids content was used and a humidifying spray of 48ml/min was applied. Surface replication is complete and the smoothness value has been greatly increased. For samples 3.7 to 3.12, a 30% solids coating was used. When the moisturizing spray (3.7) was not used, complete release was obtained but only a small percentage of the surface was replicated. When using a humidifying spray (3.8) at 48ml/min, the reproduction was greatly improved, but the surface was still blotchy with areas of poor reproduction. When the humidifying spray was increased to 98ml/min (3.9, 3.10, 3.11 and 3.12), the replication was complete and smoothness was greatly improved with minimal thickness reduction. Then, reduce the coating solids. Good release and full replication was obtained at 17.5% coating solids (3.13, 3.14) and no moisturizing spray applied. At 10% solids (3.15) and no moistening spray was applied, the low paint viscosity resulted in reduced coat weight and increased paint absorption into the tablet, thus resulting in poor replication. the

A smooth product sample prepared at 20% solids using starch as the polymer coating was top coated with a conventional pigmented clay paint (approximately 2/3 clay and 1/3 carbonate with latex binding) applied on top of the smooth polymer layer agent, applied in a single coat of approximately 101b/3000ft ² ). These samples were then sectioned to examine the morphology of the paint layer. Sectioning was performed by freezing the sample in liquid nitrogen and then breaking the sample in half (freeze fracture). The cleaved edge (eg, cross-section) of the sample is then observed under a microscope.

The photomicrographs showed the presence of voids in the polymer coating layer, as shown in Figures 2 to 9, which include gauge bars indicating their scale. For Figures 2-5, the micrographs were magnified at 1000 and the bars were measured to be 20 microns long. For example in FIG. 2 , the structure shown includes a cardboard substrate 110 . The substrate thickness generally extends below the micrograph area. The substrate 110 shown in the micrograph is sometimes detached or partially detached from the polymer layer 120 due to the freeze fracturing process. Therefore, it is only possible to roughly show the upper boundary of the substrate 110 by indicating the frame-in distance of the substrate. the

In these samples, a polymeric coating layer 120 was applied to a substrate 110 and dried against a heated drum, as previously described. A topcoat 130 is then applied and dried. The term "polymer coating" is used herein to describe a layer applied as described above and then contacting a heated drum while wet. The term "topcoat" is used to describe an outer layer, which is applied as one layer. Obviously, more layers of "topcoat" can be applied and can be of different coating materials than those used here. the

Voids 121 are evident in the polymer coating layer 120, as seen in Figures 2-9. For example, Figure 2 shows several voids 121 in the polymer coating layer 120, the voids appear to have a lateral dimension of about 5-20 microns. They are assumed to be in about the same range of sizes that "go" into the fractured sample. The void generally appears to "flatten" slightly in the "vertical" direction, ie, into the thickness of the sample. The voids also appear to have relatively smooth and generally thin "walls". These thin walls are most visible between adjacent voids. Where the void wall is close to the topcoat 130, its thickness may be difficult to see, but its presence may be inferred from the smooth lower profile of the topcoat 130 close to the void. the

FIG. 3 is an exemplary photomicrograph showing several voids 121 in a polymer coating layer. The voids appear to extend over an area equal to more than half the area of the surface being coated. The polymer coating layer is less clearly outlined in this photomicrograph. the

FIG. 4 is an exemplary photomicrograph showing several voids 121 in polymer coating layer 120 . The walls of the voids appeared thinner, as evidenced by the slightly translucent appearance in the walls of 2 voids. the

For Figures 5-9, the microscope magnification was 500 and the bars were measured to be 50 microns long. Figure 5 shows a number of voids 121 in the polymer layer 120, with individual measurement bars showing the size of the selected voids, for example, moving generally from left to right, measuring 10.5 microns vertically, 36 microns laterally, and 10.6 microns vertically. microns, and the lateral distance is 36.3 microns. Likewise, the voids appear to extend over an area equal to about half the area of the surface being coated. the

Figure 6 shows another sample with a similar measurement bar, for example, moving generally from left to right, measuring 8.66 microns in the vertical distance, 32.1 microns in the lateral distance, 11.8 microns in the vertical distance, and 22.7 microns in the lateral distance. Measurements such as those in FIGS. 5 and 6 were collected for the graph discussed below in FIG. 17 . the

Figure 7 shows voids 121 in polymer layer 120, including several that show a generally flattened aspect. The voids appear to extend over an area equal to approximately the entire coated surface area. FIG. 8 shows another sample with similarly widespread voids 121 . Several void wall regions are visible. Figure 9 shows yet another sample in which the voids 121 appear to extend over an area equal to approximately the area of the entire coated surface. the

Other samples of smooth products produced at 20% solids using starch as the polymer coating were not topcoated. These samples were cut open to examine the morphology of the paint layer. Sectioning was performed by freezing the sample in liquid nitrogen and then breaking the sample in half (freeze fracture). The cleaved sides (eg, cross-sections) of the samples were then viewed under a microscope, as shown in Figures 10-12, which include measurement bars indicating their dimensions. The microscope magnification was 1000 and the measurement bars were 20 microns long. Figure 10 shows a polymer layer 120 which contains voids 121 and has a very smooth outer surface. The polymer layer is on a paperboard substrate 110 and one cellulose fiber 112 is indicated. The substrate thickness generally extends below the micrograph area. the

Figures 11 and 12 show additional photomicrographs of samples coated with polymer but not topcoated. Likewise, the smoothness of the polymer layer 120 is evident, as is the underlying void 121. The walls of the void generally conform to the surface of the polymer coating. the

Figure 13 (at 200x magnification) and Figure 14 (at 500x magnification) show the surface of the sample viewed under a scanning electron microscope. These samples were not given a topcoat 130. The larger rope-like structures 112 are the cellulose fibers of the substrate 110 . Smaller cellular structures 122 appearing as a fine network or mesh are individual voids in polymer layer 120 . Here the polymer layer appears substantially transparent, except for the walls of the voids. the

Figures 15 and 16 show the surface of the sample observed under a backscattered scanning electron microscope. These samples were not given a topcoat 130. The larger rope-like structures 112 are the cellulose fibers of the substrate 110 . Smaller cellular structures 122 appearing as a fine network or mesh are the walls of the individual voids in the polymer layer 120 . Here the polymer layer appears substantially transparent, except for the walls of the voids. The voids appear to be distributed over the entire surface. the

Figure 17 is a graph showing the distribution of void sizes based on approximately 90 measurements each of void width (lateral dimension) and height (vertical dimension in photomicrographs). Measurements showed an average void width (measured in a direction parallel to the sample thickness) of about 19 microns with a standard deviation of about 9 microns. The measurements showed an average void height (measured in the direction "into" the thickness of the sample) of about 10 microns with a standard deviation of about 4 microns. the

These void sizes appear to be representative of the samples studied in this paper. However, they are not meant to be limiting, as variations in materials or processing conditions may result in other dimensions. the

It is assumed that vapor bubbles form these voids as the paint contacts the hot drum, and that the bubbles provide the force that helps keep the paint in contact with the drum. The resulting voids generally help bridge the gap between the otherwise rough substrate layer 110 and the smooth surface of the heated drum. The dried polymer paint thus has a smooth replication surface, which is smoother than the substrate layer 110 . It appears that many or most of the voids remained intact when topcoat 130 was applied. The top coat thus ends up being smoother due to the relatively smooth polymer layer 120 below. This is considered an advantage obtained by the present invention. In addition to the supposed effect of voids on helping to create a smooth replication surface, voids can also help reduce product density. the

Conditions in the nip between press roll 24 and heated drum 22 can affect whether voids form in the polymer coating. Depending on the press roll hardness and the diameter of the press roll and heated drum, it may be necessary to adjust the nip load (eg, PLI load on the nip) in order to achieve boiling in the nip to form the void. the

The polymer coated paper or paperboard formed by this method can be used wherever a smooth substrate or end product is desired. Polymer coated paper or paperboard can be used as is (such as shown in Figures 10-16), or can be used as a topcoat 130 or other treatment (such as shown in Figures 2-9) to which other coatings or other treatments are applied. Coated) substrates are used. Additional finishing materials or methods can be applied to polymer coated paper or paperboard, with or without additional coatings. For example, one or more additional coats may be applied, typically base coats, top coats and triple coats of conventional paper or paperboard substrates. The calendering process can be applied before or after the optional additional coating. For example, one or more additional coats may be applied, followed by a gloss calendering step. the

Methods of making and using polymer-coated materials in accordance with the present invention should be readily apparent from the mere description of the materials and methods provided herein. Accordingly, no further discussion or illustration of such materials or methods is deemed necessary. the

While preferred embodiments of the invention have been described and illustrated, it will be obvious that various changes can be made in the embodiment and practice of the invention without departing from the spirit or scope of the invention. Although the preferred embodiments illustrated herein are described in connection with a paper or paperboard substrate, these embodiments can be readily implemented in other structures according to the invention, including but not limited to fabrics, nonwovens, fibrous materials, polylactic acid substrates and porous membranes. the

Therefore, it should be realized that the invention is not limited to the particular embodiments disclosed (or apparent from the disclosure), but is only limited by the appended claims. the

Claims (53)

1. the product that obtains by processing substrate comprises:

Substrate; With

The first coating on described substrate,

Wherein said the first coating comprises water-soluble polymers and release agent, and

Wherein in described the first coating, form the space,

Wherein said the first coating comprises the surface, and at least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, described the first coatingsurface has the Sheffield smoothness less than 200 units, and wherein said water-soluble polymers comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

2. the product of claim 1, wherein said water-soluble polymers comprise at least a in casein and the soybean protein.

3. the product that obtains by processing substrate comprises:

Substrate; With

The first coating on described substrate,

Wherein said the first coating comprises that water-soluble polymers, release agent also do not have elastomer material substantially,

Wherein said the first coating comprises the surface,

Wherein said the first coatingsurface has the Sheffield smoothness less than 200 units, and

Wherein under the described surface of described the first coating, form the space, and at least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

4. the product that obtains by processing substrate comprises:

Substrate; With

The first coating on described substrate,

Wherein said the first coating comprises that water-soluble polymers does not also have elastomer material substantially, and

Wherein in described the first coating, form the space,

Wherein said the first coating comprises the surface, and at least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, described the first coatingsurface has the Sheffield smoothness less than 200 units, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

5. claim 1,3 or 4 product also are included in the second coating on described the first coating.

6. claim 1 or 4 product, wherein said the first coating comprises the surface that has less than the Sheffield smoothness of 150 units.

7. the product that obtains by processing substrate comprises:

Substrate; With

The first coating on described substrate,

Wherein said the first coating comprises the surface,

Wherein said the first coatingsurface has the Sheffield smoothness less than 200 units, and

Wherein under the described surface of described the first coating, form the space, and described the first coatingsurface at least 50% have lateral dimension and be space under at least 5 microns the surface,

Wherein said the first coating comprises at least 60% water-soluble polymers and 10% release agent at the most with dry weight basis, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

8. claim 1 or 7 product, wherein said the first coating does not comprise elastomer material substantially.

9. claim 1,3,4 or 7 product, wherein said the first coating comprises linking agent.

10. claim 1,3 or 4 product, wherein said the first coating comprises at least 60% water-soluble polymers and 10% release agent at the most with dry weight basis.

11. claim 3,4 or 7 product, wherein said the first coating comprise at least a in casein and the soybean protein.

12. the product of claim 3 or 7, wherein said surface have the Sheffield smoothness less than 150 units.

13. process the method for substrate, comprise step:

The first coating of aqueous solutions of polymers is applied on the described substrate as film; With

Fix described aqueous solutions of polymers by the surface that makes described aqueous solutions of polymers Contact Heating to cause described aqueous solutions of polymers boiling and to form the space that is retained in the described aqueous solutions of polymers,

Wherein said fixing step comprises the described aqueous solutions of polymers of at least part of drying, and described film comprises the surface, and at least 50% of described surface has lateral dimension and is space under at least 5 microns the surface, the described surface of described film has the Sheffield smoothness less than 200 units after drying, wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

14. contacting the surface of described heating, the method for claim 13, wherein said film be less than 3 seconds the timed interval.

15. contacting the surface of described heating, the method for claim 14, wherein said film be less than 2 seconds the timed interval.

16. contacting the surface of described heating, the method for claim 15, wherein said film be less than 0.5 second the timed interval.

17. the method for claim 13, wherein the described film of the aqueous solutions of polymers surface that contacts described heating is less than 3 seconds, and the surface of wherein said heating has and is higher than 150 ℃ temperature.

18. process the method for substrate, comprise step:

The first coating of aqueous solutions of polymers is applied on the described substrate as film,

Wherein said the first coating comprises water-soluble polymers and release agent,

Be less than 3 seconds in order to cause the boiling of described aqueous solutions of polymers and in described film, form the space and fix described film by the heating surface that makes described film Contact Temperature be higher than 150 ℃,

Wherein said fixing step comprises the described film of at least part of drying, wherein

At least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, and described the first coatingsurface has the Sheffield smoothness less than 200 units, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

19. process the method for substrate, comprise step:

The first coating of aqueous solutions of polymers is applied on the described substrate as film,

Wherein said the first coating comprises that water-soluble polymers does not also have elastomer material substantially,

Be less than 3 seconds in order to cause the boiling of described aqueous solutions of polymers and in described film, form the space and fix described film by the heating surface that makes described film Contact Temperature be higher than 150 ℃,

Wherein said fixing step comprises the described film of at least part of drying, wherein

At least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, and described the first coatingsurface has the Sheffield smoothness less than 200 units, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

20. claim 13,18 or 19 method, wherein linking agent is included in described the first coating before described film contacts described heating surface or is applied to described the first coating.

21. process the method for substrate, comprise step:

The first coating of aqueous solutions of polymers is applied on the described substrate as film,

Be less than 3 seconds in order to cause the boiling of described aqueous solutions of polymers and in described film, form the space and fix described film by the heating surface that makes described film Contact Temperature be higher than 150 ℃,

Wherein said fixing step comprises the described film of at least part of drying,

Wherein said the first coating comprises the surface,

Wherein dried described the first coatingsurface has the Sheffield smoothness less than 200 units,

At least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

22. claim 13,18,19 or 21 method, the surface that wherein said film contacts described heating is less than 2 seconds time.

23. contacting the surface of described heating, the method for claim 22, wherein said film be less than 0.5 second time.

24. claim 13,18,19 or 21 method, wherein said substrate comprises the width of cloth or sheet.

25. claim 13,18,19 or 21 method, wherein said substrate comprises Mierocrystalline cellulose.

26. claim 13,18,19 or 21 method, wherein said substrate comprise at least a in paper, cardboard, filamentary material, porous material or the poly(lactic acid).

27. the method for claim 26, wherein said substrate comprise at least a in fabric or the porous-film.

28. claim 13,18,19 or 21 method, wherein said aqueous solutions of polymers comprises crosslinkable polymer.

29. claim 13,18,19 or 21 method, wherein said aqueous solutions of polymers does not comprise elastomer material substantially.

30. claim 13,18,19 or 21 method, wherein linking agent is included in described the first coating before described film contacts described heating surface or is applied to described the first coating; Wherein said linking agent comprises at least a in borate, aldehyde, ammonium salt and the calcium cpd.

31. the method for claim 30, wherein said linking agent comprises borax.

32. claim 13,18,19 or 21 method, wherein said the first coating comprises at least 60% water-soluble polymers and 10% release agent at the most with dry weight basis; Wherein said release agent comprises at least a in wax, fatty acid metal soap, fatty ester, fatty amide, aliphatic amide, lipid acid, Fatty Alcohol(C12-C14 and C12-C18), polymkeric substance, fluorinated compound and its combination.

33. the method for claim 32, wherein said release agent comprise at least a in petroleum wax, vegetable wax, animal wax, synthetic wax, metallic stearate, polyolefine, silicone polymer, fluoropolymer, natural polymer, fluoride fat acid and its combination.

34. claim 13,18,19 or 21 method, wherein said the first coating comprise at least a in casein and the soybean protein.

35. claim 13,18,19 or 21 method, wherein said the first coatingsurface has the Sheffield smoothness less than 150 units.

36. claim 13,18,19 or 21 method, described method also is included in the step of after-applied the second coating of the described film of at least part of drying, and wherein said the second coating comprises at least a in pigment, tackiness agent and the filler.

37. process the method for substrate, comprise step:

The first coating of aqueous solutions of polymers is applied on the described substrate as film,

Wherein said the first coating comprises that water-soluble polymers, release agent also do not contain elastomer material substantially,

Be less than 3 seconds in order to cause the boiling of described aqueous solutions of polymers and in described film, form the space and fix described film by the heating surface that makes described film Contact Temperature be higher than 150 ℃,

Wherein said fixing step comprises the described film of at least part of drying,

Wherein said the first coating comprises the surface,

Wherein dried described the first coatingsurface has the Sheffield smoothness less than 200 units,

At least 50% of described the first coatingsurface has lateral dimension and is space under at least 5 microns the surface, and wherein said the first coating comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

38. the method for claim 37, wherein said film contacts the time that described heating surface is less than 2 seconds.

39. the method for claim 38, wherein said film contacts the time that described heating surface is less than 0.5 second.

40. the method for claim 37, wherein said substrate comprises the width of cloth or sheet.

41. the method for claim 37, wherein said substrate comprises Mierocrystalline cellulose.

42. the method for claim 37, wherein said substrate comprise at least a in paper, cardboard, filamentary material, porous material or the poly(lactic acid).

43. the method for claim 42, wherein said substrate comprise at least a in fabric or the porous-film.

44. claim 18,19 or 37 method, wherein said water-soluble polymers comprises crosslinkable polymer.

45. the method for claim 37, wherein linking agent is included in described the first coating before described film contacts described heating surface or is applied to described the first coating; Wherein said linking agent comprises at least a in borate, aldehyde, ammonium salt and the calcium cpd.

46. the method for claim 45, wherein said linking agent comprises borax.

47. the method for claim 37, wherein said the first coating comprises at least 60% water-soluble polymers and 10% release agent at the most with dry weight basis, and release agent comprises at least a in wax, fatty acid metal soap, fatty ester, fatty amide, aliphatic amide, lipid acid, Fatty Alcohol(C12-C14 and C12-C18), polymkeric substance, fluorinated compound and its combination.

48. the method for claim 47, wherein said release agent comprise at least a in petroleum wax, vegetable wax, animal wax, synthetic wax, metallic stearate, polyolefine, silicone polymer, fluoropolymer, natural polymer, fluoride fat acid and its combination.

49. the method for claim 37, wherein said the first coating comprise at least a in casein and the soybean protein.

50. the method for claim 37, wherein said the first coatingsurface has the Sheffield smoothness less than 150 units.

51. the method for claim 37, described method also are included in the step of after-applied the second coating of the described film of at least part of drying, wherein said the second coating comprises at least a in pigment, tackiness agent and the filler.

52. process the method for substrate, comprise step:

The Mierocrystalline cellulose substrate is provided;

Apply the aqueous solutions of polymers film to described substrate,

Wherein said aqueous solutions of polymers comprises at the most 10% release agent of the water-soluble polymers of dry weight at least 60% and dry weight,

Be less than 3 seconds in order to cause the boiling of described aqueous solutions of polymers and in described aqueous solutions of polymers, form the space and fix described aqueous solutions of polymers by the heating surface that makes described aqueous solutions of polymers Contact Temperature be higher than 150 ℃,

Wherein said fixing step comprises the described aqueous solutions of polymers of at least part of drying, and described film comprises the surface, and at least 50% of described surface has lateral dimension and is space under at least 5 microns the surface, the described surface of described film has the Sheffield smoothness less than 200 units after drying, wherein said water-soluble polymers comprises at least a in starch, waxy corn, protein, polyvinyl alcohol, gelatin and the alginate.

53. claim 13,18,19,21,37 or 52 method also are included in the step of after-applied the second coating of the described film of at least part of drying.

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