JP4903359B2 - Method for producing multilayer coated support with improved barrier properties - Google Patents

Abstract

Production of a coated substrate involves contacting a multilayer free flowing curtain with a continuous web substrate. Production of a coated substrate involves contacting a multilayer free flowing curtain with a continuous web substrate. The multilayer free flowing curtain comprises at least two layers imparting at least two different barrier functionalities selected from oil and/or grease barrier, water vapor barrier, water resistance or oxygen barrier functionality. The coated substrate has a kit value of at least 5 (preferably at least 8, especially at least 11) in the flat-test when an oil and/or grease barrier layer is present; has a water vapor transmission rate of less than 50 (preferably less than 40, especially less than 30) g/(m 2>/day) (50% relative humidity, 23[deg]C) when a water vapor barrier layer is present; has a 10 minute Cobb value of less than 20 (preferably less than 12, especially 1.5) g/m 2> when water resistance layer is present; and has an oxygen transmission rate of less than 200 (preferably less than 150, especially less than 100) cm 2>/(m 2>/24 hour/bar) (1 atm, 23[deg]C, 90% relative humidity) when an oxygen barrier layer is present.

Description

  The present invention relates to a method for producing a coated support having barrier properties.

  Supports with barrier properties are very important for packaging food, beverages or other products that are sensitive to the environment. These supports are generally provided with a barrier layer using known coating techniques such as blade coating, bar (rod) coating, reverse roll (film) coating or air knife coating. However, each of these application methods has problems that can result in poor barrier quality. In addition, a common feature of all these methods is that the amount of coating liquid applied to a paper web, which usually has irregular surfaces with irregularities, depends on whether it is applied in a concave or convex manner. is there. Accordingly, the coating thickness varies over the entire coated support surface, and therefore the barrier property also varies, resulting in barrier irregularities. Furthermore, the method is also limited in that it is thin enough that the coating layer can be applied to the support. Another disadvantage of the application methods known from the prior art is that only one layer can be applied to the support at each application station. If several barrier layers are applied to the support, each of the application layers requires a subsequent application in a separate application station or further application machine. Such a continuous approach to creating a multilayer coating is undesirable because it is not successful in prior art continuous application processes when additional layers are to be applied to the hydrophobic and highly water repellent layers. Despite its drawbacks, these coating methods are still the main method in the paper industry because they are economical and can achieve very high line speeds.

Curtain coating is a relatively new coating technique. European Patent Application Publication No. 517223 and Japanese Patent Application Nos. 6-89437, 5-311931, 5-177816, 5-131718, 4-298683, and 4-51933. JP-A-3-298229, JP-A-2-217327 and JP-A-8-310110 disclose the use of a curtain coating method in which one or more colored paint layers are applied to the surface of a moving paper. . More specifically, the prior art relates to the following method.
(I) A curtain coating method used for producing a single-layer colored coating film on paper by applying a single layer of colored paint to a base paper support.
(Ii) A curtain coating method used to apply an undercoat monolayer of colored paint to a base paper support prior to applying a single layer of pigment overcoat by a blade type coating process. Therefore, a multilayer colored coating on paper was achieved by continuous application of colored paint.
(Iii) A curtain coating method used to apply a finished single layer of colored paint to a base paper support previously primed with a single layer of colored primer applied by a blade or metering roll type coating process. Therefore, a multilayer colored coating on paper was achieved by continuous application of colored paint.
(Iv) A curtain coating method used to apply two single layers of special colored paint to a base paper support so that the single layers are applied in a sequential process. Therefore, a multilayer colored coating on paper was achieved by continuous application of colored paint.

  The use of the curtain coating method for applying a single layer of colored paint to the surface of a moving web of paper is superior in quality compared to that produced by conventional coating means, as disclosed in the prior art above. It is said to provide an opportunity to produce a coated paper surface. However, due to the dynamics of the curtain coating process, a single layer of colored paint must be continuously applied using curtain coating technology. Specifically, lightweight paint application is possible only at application speeds less than those currently used by conventional application processes, but this can cause the curtain to become unstable at high application speeds and thereby poor application. This is because a film surface is generated. Thus, conventional methods for producing multilayer coated paper and paperboard utilize a blade, rod or roll metering process. Unfortunately, the sequential application of colored paints to paper or paperboard at a continuous application station can be achieved by any of the above application methods, such as the number of application stations required, e.g. drives, dryers, etc. It remains a capital intensive process because of the amount of auxiliary equipment required and the space required to accommodate the complete machine.

  Curtain coating methods for simultaneous coating of multiple layers are known and are described in US Pat. Nos. 3,508,947 and 3,632,374 for coating photographic compositions on paper and plastic webs. Has been. However, photographic solutions or emulsions have low viscosity and low solids and are coated at low coating speeds.

The simultaneous application of a plurality of paints by the curtain coating method is known in the technical field of producing pressure-sensitive copy paper in addition to photographic applications. For example, U.S. Pat. No. 4,230,743, in one embodiment, discloses the simultaneous application of a base coat containing microcapsules as a main component and a second layer containing a color former as a main component on a running web. is doing. However, the paper obtained thereby has been reported to have the same properties as paper made by continuous application of layers. Furthermore, it is described that the coating composition containing a color former has a viscosity of 10 to 20 mPa · s at 22 ° C.

  Japanese Patent Application Laid-Open No. 10-328613 discloses a method for producing inkjet paper by simultaneously applying two paint layers onto a paper web by curtain coating. The coating composition applied in accordance with the teachings of the above document is an aqueous solution having a very low solid content of 8% by weight. In addition, thickeners have been added to obtain the non-Newtonian behavior of the coating solution. Examples in JP 10-328613 reveal that acceptable coating quality can only be obtained at line speeds below 400 m / min.

  In view of the disadvantages of the prior art, it would be desirable to have an economical and improved process for preparing a substrate, such as paper or paperboard, that has barrier properties.

  The technical problem underlying the present invention is the provision of a method for producing a coated support comprising barrier properties that overcomes the disadvantages of the prior art. A further object of the present invention is to apply a plurality of barrier layers to the support, whereby each barrier layer imparts a specific barrier functionality, so that a specific barrier is selected by selecting the specific layer. A support having flexibility can be designed.

The technical problem of the present invention is solved by a method for producing a coated support including the following steps.
a) forming a composite multi-layer free-flowing curtain, whereby the multi-layer free-flowing curtain has oil and / or grease barrier functionality, water vapor barrier functionality, water resistance functionality, solvent barrier functionality, It includes at least two layers that impart at least two different barrier functionality selected from the group consisting of fragrance barrier functionality and oxygen barrier functionality. And b) contacting the curtain with a continuous web support, whereby
If an oil and / or grease barrier layer is present in the multilayer curtain, the coated substrate has a kit value of at least 5 in a flat-test,
When a water vapor barrier layer is present in the multilayer curtain, the coated support has a water vapor transmission rate of less than 50 g / m ² / day ( relative humidity 50%, 23 ° C.);
When a water resistant layer is present in the multilayer curtain, the coated support has a 10 minute Cobb value of less than 20 g / m ² ;
If the oxygen barrier layer is present in the multilayer curtain the coated substrate has a 200 cm ³ / m ^2/24 hr / bar Le (1 atm, 23 ° C., 90% relative humidity) less than the oxygen permeability of.
For the purposes of the present invention, when organic solvent barrier functionality is present, the coating provides a barrier to organic solvents according to commercially acceptable standards. For purposes of the present invention, where fragrance barrier functionality is present, the coating provides a barrier to fragrance according to commercially acceptable standards.

  As used herein, the term “coated substrate” includes coated base paper or paperboard. The term “continuous web support” encompasses a continuous web support of base paper and paperboard. Further, as used herein, the term “barrier layer” is understood as a layer that imparts at least one barrier functionality as defined above.

  The multilayer free-flowing curtain of the present invention has a bottom or interface layer, a top layer and optionally one or more inner layers. The coated curtain of the present invention comprises at least 2 layers, preferably at least 3 layers, even more preferably at least 4 layers, more preferably at least 5 layers, and most preferably at least 6 layers. The curtain layer may be one or more printed layers, one or more functional layers, one or more spacing layers, one or more paint layers and layers that provide barrier functionality, or the like Any combination may be included. A spacing layer is a layer that separates at least two other layers. Each layer of the curtain includes a liquid, emulsion, dispersion, suspension or solution. In a preferred embodiment, the free-flowing curtain of step a) includes a top layer that provides printability.

  Preferably, the multilayer curtain of step a) is clay, kaolin, calcined clay, talc, calcium carbonate, titanium dioxide, satin white, synthetic magnesium pigment, synthetic polymer pigment, zinc oxide, barium sulfate, gypsum, silica, alumina trihydrate. And at least one layer containing at least one pigment such as mica and diatomaceous earth. Particularly preferred are synthetic polymer pigments including kaolin, talc, calcium carbonate, titanium dioxide, satin white and hollow polymer pigments. In order to improve the barrier properties, at least one layer may contain specific plate pigments such as talc, laminar nanoparticles, high aspect ratio clay, mica, synthetic magadite.

  Furthermore, in the multilayer curtain of step a), at least one layer contains a binder. Binders useful in the practice of the present invention include, for example, styrene-butadiene latex, styrene-acrylate latex, styrene-butadiene-acrylonitrile latex, styrene-acrylate-acrylonitrile latex, styrene-butadiene-acrylate-acrylonitrile latex, styrene-anhydrous malein. There are acid latex, styrene-acrylate-maleic anhydride latex, polysaccharides, protein, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetate, cellulose and cellulose derivatives. Examples of preferred binders include carboxylated styrene-butadiene latex, carboxylated styrene-acrylate latex, carboxylated styrene-butadiene-acrylonitrile latex, carboxylated styrene-maleic anhydride latex, carboxylated polysaccharide, protein, polyvinyl alcohol, carboxyl Polyvinyl acetate latex and mixtures thereof. Examples of polysaccharides include starches including agar, sodium alginate and modified starches such as heat modified starch, carboxymethylated starch, hydroxyethylated starch and oxidized starch. Examples of proteins that can be suitably used in the process of the present invention include albumin, soy protein and casein.

By adjusting the coating amount of each layer of the curtain, the desired properties of the coated support can be obtained. At least one of the layers of the multilayer curtain of step a) is suitably less than 30 g / m ² , preferably less than 20 g / m ² , more preferably less than 10 g / m ² and even more preferably less than 5 g / m ^2. Most preferably, it has a dry coating weight of less than 3 g / m ² .

The coating film prepared from the multilayer curtain in step a) has a dry coating amount on the produced paper of preferably 3 to 60 g / m ² , more preferably 5 to 25 g / m ² . Coating prepared from the curtain, dry coating amount is preferably in the range of less than 60 g / m ^2, or 30 g / m less than ^2, or 20 g / m less than ^2, or 15 g / m less than ^2, or 12 g / m ² Or less than 10 g / m ² , most preferably less than 5 g / m ² .

The viscosity and solid content of each barrier layer may vary within a wide range depending on the desired function. Any combination of viscosity and solids can be used as long as suitable barrier properties are obtained. Each barrier layer present in the multilayer curtain of the present invention preferably has a solids content of up to 75% by weight and a maximum of 3,000 mPa · s (Brookfield, spindle 5, 100 rpm, 25 ° C.), more preferably 30. It has a viscosity of ˜2,000 mPa · s . The coating amount of the barrier layer is preferably 0.1 to 30 g / m ² , more preferably 1 to 10 g / m ² . The viscosity of the barrier layer is desirably at least 50 mPa · s , preferably at least 100 mPa · s , more preferably at least 200 mPa · s , and even more preferably 230 to 2000 mPa · s .

  The free-flowing curtain of step a) has a solids content of at least 10% by weight, preferably at least 40% by weight, more preferably at least 45% by weight and most preferably at least 50% by weight. The viscosity of the curtain layer is not critical as long as the layer forms a free-flowing curtain.

  The curtain of step a) of the present invention may further comprise one or more non-barrier functional layers. The purpose of the functional layer is to impart desired functionality to the coated paper. Select functional layer, for example, printability, sheet rigidity, sheet flexibility, crack resistance, paper sizing, peelability, adhesiveness, heat sealability, abrasion resistance and color, brightness, opacity Optical properties such as gloss can be given. Functional paints that are highly tacky in nature cannot usually be applied in any way by conventional sequential application processes due to the tendency of the adhesive paint material to adhere the support to a guiding roll or other application device. It was. On the other hand, the simultaneous multi-layer method allows such functional paints to be applied under the topcoat that protects the functional coating from contact with the applicator.

  The barrier property of the coated support is preferably maintained even after the support is folded or bent. The crease resistance of the coated support can be determined by visual inspection of the folded support using a Heildelberg Quickfolder that wrinkles the coated sample. The crack resistance of the coated support of the present invention is preferably at least 2. In certain embodiments of the invention, a flexible functional layer and / or a flexible barrier layer is utilized to increase the fold resistance of the coated support.

In a preferred embodiment, the multilayer curtain of step a) is, for example, ethylene acrylic acid copolymer, ethylene vinyl alcohol copolymer, polyurethane, epoxy resin, polyester, polyolefin, carboxylated styrene butadiene latex, carboxylated styrene acrylate latex, polyvinylidene chloride, Polyvinyl chloride, starch, protein, styrene acrylic copolymer, styrene maleic anhydride copolymer , polyvinyl alcohol, polyvinyl acetate, carboxymethyl cellulose, silicone, wax, neoprene, polyhydroxy ether, lacquer, polylactic acid, polylactic acid copolymer, containing fluorine atoms Polymer, carboxylated styrene butadiene acrylonitrile copolymer, etc. Comprising at least one layer a layer of imparting barrier functionality comprising at least one or more components of acrylonitrile copolymers and mixtures thereof.

In the composite multilayer free-flowing curtain of step a), the interface layer that is a layer in contact with the support to be coated is preferably not a barrier layer. One important function of the interface layer is to increase the wettability of the support. The interface layer may have two or more functions. For example, in addition to wettability, the interfacial layer may provide support functionality as well as improved functionality such as adhesion, sizing, stiffness, or a combination of functions. This layer is preferably a relatively thin layer provided it does not provide additional functionality. Coating amount of the surface layer is preferably 0.1 to 30 g / m ^2, preferably from 1 to 3 g / m ^2. The solid content of the interface layer is preferably 0.1 to 75% with respect to the mass of the interface layer in the curtain. In certain embodiments, the interfacial layer has a relatively low solids content, preferably 0.1 to 40% solids. The viscosity of the interfacial layer is preferably at least 55 mPa · s , more preferably at least 100 mPa · s , even more preferably at least 200 mPa · s . The viscosity of the interface layer is preferably 230 to 2000 mPa · s .

  In a preferred embodiment, at least one layer of the multi-layer free-flowing curtain of step a) comprises additives commonly used by those skilled in the art, such as at least one surfactant, at least one dispersant, at least one lubricant. At least one water retention agent, at least one crosslinking agent, at least one fluorescent brightener, at least one pigment dye or colorant, at least one thickener, at least one antifoaming agent, Additives such as at least one antifoam agent, at least one biocide or at least one soluble dye or colorant. Mixtures of additives may be used.

  The coating agent is preferably degassed before application in order to remove bubbles in the paint that may cause application defects.

  The curtain layer can be applied simultaneously by the present invention using a curtain coating apparatus equipped with a slide nozzle arrangement for discharging a plurality of liquid layers to form a continuous multilayer curtain. Alternatively, an extrusion-type delivery head such as a slot die or nozzle having several adjacent extrusion nozzles can be used in the practice of the present invention.

  The barrier properties of the obtained coated support can be measured by methods commonly used by those skilled in the art.

  If an oil and / or grease barrier layer is present in the multilayer curtain, it is preferred that the coated substrate has a kit value of at least 5 in the flat test and / or a kit value of at least 3 in the wrinkle test. If an oil and / or grease barrier layer is present in the multi-layer curtain, it is preferred that the coated support passes a hot oil (oleic acid) stain resistance test, details of which are described herein below. In a preferred embodiment, if an oil and / or grease barrier layer is present in the multilayer curtain of step a), the coated paper or paperboard has a kit value of at least 8 in flat testing, more preferably at least 11, most preferably Has a kit value of at least 12. Furthermore, if an oil and / or grease barrier layer is present in the multilayer curtain of step a), the coated paper or paperboard has a kit value of at least 4 in the wrinkled kit, more preferably at least 7.

The coated support preferably has a water vapor transmission rate of less than 40 g / m ² / day (relative humidity 50%, 23 ° C.), more preferably less than 30 g / m ² / day , most preferably 10 g / m ² / day. Is less than.

When a water resistant layer is present in the multilayer curtain, the coated support is preferably less than 12 g / m ² , more preferably less than 6, even more preferably less than 1.5 g / m ² , most preferably 0.5 g / m ^2. It has a 10 minute Cobb value of less than m ² .

If the oxygen barrier layer is present in the multilayer curtain, the coated support is preferably 150 cm ³ / m ^2/24 hr / bar Le (1 atm, 23 ° C., 90% relative humidity), more preferably less than 100 cm ³ / m ^2/24 hr / bar le less than, even more preferably 50 cm ³ / m ^2/24 hr / bar le less than the oxygen permeability of.

  In certain embodiments, the continuous web support of step b) is neither primed nor pre-calendered. In other embodiments, the continuous web support of step b) is not primed, and in a further embodiment, the continuous web support of step b) is not pre-calendered.

  The continuous web support of step b) may have a web speed suitable for preparing an acceptable coated support. The speed is preferably at least 200 m / min, more preferably at least 400 m / min, even more preferably at least 500 m / min, most preferably at least 800 m / min.

It is preferred that the basis weight, i.e. the basic mass, of the continuous web support in step b) is 30 to 400 g / m < ² >.

  FIG. 1 is an explanatory cross-sectional view of a preferred curtain coating apparatus 1 having a slide nozzle arrangement 2 for discharging a plurality of flows 3 of curtain layers to form a continuous multilayer curtain 4. When the dynamic equilibrium is reached, the flow rate of the curtain layer flowing into the slide nozzle arrangement 2 is completely balanced with the flow rate flowing out of the slide nozzle arrangement. The freely falling multilayer curtain 4 is in contact with a continuously running web 5, so that the web 5 is applied by a plurality of layers of respective curtain layers. The running direction of the web 5 is changed immediately before the application area by the roller 6 to minimize the influence of the airflow accompanying the web 5 moving at high speed.

  The advantage of the present invention over the prior art is that a coated barrier support with specific barrier properties can be obtained by combining specific functional layers in a multilayer curtain. The technique allows several barrier layers to be applied to the support in one application process. Furthermore, the applied barrier layer can be thinner than the state of the art barrier layer. The method of the present invention also overcomes the problem of wetting or water repellency of the coating on the already dried barrier layer, which is a problem in multi-stage film press or blade application. The coated support of the present invention is useful for flexible packaging and liquid packaging, and can also be used as an economical protector for processed products.

  The invention is illustrated by the following examples. Unless otherwise noted, all parts and percentages are by weight.

Test method
Hot oil test A hot oil (oleic acid) at 60 ° C. is placed on the sample at room temperature for 1 hour, and visually checked for the presence or absence of stains. If there is a stain, the result is rejected. The passed room temperature sample is placed in an oven at 60 ° C. for 24 hours, after which the oil is rubbed off and visually checked for sample smudges. If there is no stain, the result is acceptable, and if there is a stain, the result is unacceptable.

Water vapor transmission rate (MVTR)
The water vapor barrier is measured using the Technical Association of the Pulp and Paper Industry (TAPPI) test T-448. This method describes a means for testing water vapor transmission rate at a temperature of 23 ° C. and a relative humidity of 50%. The unit is g / m ² / day.

Cobb test water resistance is measured as the resistance of the coating to the passage of water with stirring on the surface. This test is cob size. The Cobb method measures the water absorption of paper and is performed according to the test procedure defined in TAPPI T-441.

Kit Test The 3M kit test is performed according to the test procedure defined in TAPPI T-559.

Oxygen Barrier The oxygen barrier test is performed according to the test procedure defined in ASTM D1434.

Fracture resistance The crack resistance of a coated substrate can be measured by visual inspection of the folded substrate using a Heildelberg Quickfolder that wrinkles the coated sample. Before folding, the sample is conditioned at 25 ° C. and 50% relative humidity for 24 hours, and then a black ink film is applied to increase the contrast. After folding, the wrinkles are visually inspected and evaluated on a 1-5 scale. A rating of 1 indicates that there is no damage to the film in the wrinkle. A rating of 2 indicates that the film remains intact with some damage. A rating of 3 means that the film is damaged to the extent that peeling of the film from the support occurs. A rating of 4 means that the film fails, but there is no fiber damage. A rating of 5 means failed film and fiber damage.

Brookfield Viscosity Viscosity is measured using a Brookfield RVT viscometer (commercially available from Brookfield Engineering Laboratories, Inc., Stoughton, Massachusetts, USA). For viscosity measurement, a 600 ml sample is poured into a 1000 ml beaker and the viscosity is measured at 25 ° C. at spindle speeds of 20 and 100 rpm.

The application amount achieved in each paper application experiment is the known volumetric flow rate of the pump that discharges the paint to the curtain application head, the speed at which the continuous web of paper moves under the curtain application head, the density of the curtain and the solids content. % And curtain width.

The density of the paint density curtain layer is measured by weighing a 100 milliliter paint sample in a density bottle.

Paper Gloss The gloss of paper is measured using a Zehntner ZLR-1050 instrument at an incident angle of 75 °.

Ink Glossy Prübbau Test Printing unit, Lorrilleux Red Ink No. The test is carried out according to 8588. An amount of 0.8 g / m ² (or 1.6 g / m ² , respectively) of ink was applied to a coated paper test piece mounted on a platen with a long rubber back on the steel printing disk. The ink application pressure is 1,000 N and the speed is 1 m / sec. The printed specimen is dried for 12 hours at 20 ° C. with a minimum room humidity of 55%. Next, the gloss is measured at an incident angle of 75 ° using a Zane Toner ZLR-1050 device.

The test is performed with an ink set-off pref bow test printing device. Spread 250 mm ³ of ink (Huber No. 520068) on the distributor for 1 minute. Place a metal printing disc on the distributor for 15 seconds to apply ink. Place the disc in the first printing station. In the second printing station, a metal printing disc without ink is placed at a pressure of 400N. A test piece of coated paper on the back of a rubber platen is printed at a printing pressure of 1000 N at a speed of 1.5 m / sec. The time when printing is performed is time 0. After the test strip is printed at the first printing station, the test strip is moved toward the second printing station or set-off station by moving the hand lever. At the set-off station, a blank test piece is placed between the printed paper and the disc. The blank paper is pressed against the printed sample in the set-off station by moving the hand lever at 15, 30, 60 and 120 seconds. The amount of non-fixed ink transferred from the printed paper to the white paper is measured by the ink density given by the optical density measurement.

Luminance is measured with a Zeiss Elrepho 2000. The brightness is measured on a batch of sheets according to ISO standard 2469. Results are expressed as R457.

Dry pick resistance (IGT)
This test measures the ability of the paper surface to accept ink movement without picking. This test is performed on an A2 type printability tester commercially available from IGT Reprotest BV. Coated paper specimens (4 mm x 22 mm) are printed with an inked aluminum disc at a printing pressure of 36 N with a Leproprobe Beebuy pendulum drive system and high viscosity test oil (red). After printing is complete, the distance at which the coating begins to show picking is marked under the microscope. The marked distance is then transferred to the IGT velocity curve and the velocity in cm / sec is read from the corresponding drive curve. High speed means high resistance to dry picking.

Wet pick This test is carried out on a Prüfbau test printing device equipped with a wet chamber. Spread 500 mm ³ of printing ink (Hueber 1, 2, 3 or 4 depending on the overall wet pick resistance of the paper) on the distributor for 2 minutes and refill with 60 mm ³ of ink again after each printing. Ink is applied by placing a vulcanized rubber printing disc on the distributor for 15 seconds. Then 10 mm ³ of distilled water is added to the wet chamber and sprinkled on the rubber roll. The coated paper test piece is placed on a rubber-backed platen and printed at a printing pressure of 600 N and a printing speed of 1 m / sec. Wet the central specimen of the coated paper with a line of test water as it passes through the humid chamber. Immediately after leaving the wet chamber, printing is performed on the specimen. The printing disk is reprinted on a second coated paper test piece, the back of which is fixed on a rubber platen. The printing pressure is 400N. The ink density of both test pieces is measured and used in the following formula.

Paper Roughness The roughness of the coated paper surface is measured with a Parker PrintSurf roughness tester. A test sheet of coated paper is clamped between the Corkmelenex platen and the measuring head with a clamping pressure of 1,000 kPa. Compressed air is supplied to the apparatus at 400 kPa, and air leakage between the measuring head and the coated paper surface is measured. A large value means that the roughness of the coated paper surface is high.

The solvent resistance of the solvent resistant barrier layer is the ability to withstand the time of solvent attack with minimal changes in appearance, dimensions, mechanical properties and mass. Test conditions include exposure length, concentration, temperature and internal stress. The solvent resistance of the multilayer barrier support can be evaluated using ASTM D543. Whether it is finally classified as solvent resistant depends on the application.

Aroma barrier A barrier that prevents fragrance reduction is a substance that inhibits permeation of the aroma into the barrier layer. Permeability is determined by measuring the permeation of the fragrance into the specimen under controlled conditions of temperature and driving force. Depending on the nature of the fragrance compound, transmission can be detected using a number of analytical techniques. Permeation results are reported in units of mass divided by path length, time and pressure difference.

The following materials were used in the coating solution.
Carbonate: Dispersion (HYDROCARB 90 ME, commercially available from Omia AG, Switzerland, 90%) with calcium carbonate having a particle size of less than 2 μm dispersed in water, 77% solids.
Clay: No. 98% having a particle size of less than 2 μm. 1 Dispersion of high-intensity kaolin clay dispersed in water (HYDRAGLOSS 90, commercially available from Have De Grace, JM Huber Corp., Maryland, USA), 71% solids.
Latex (A): Carboxylated styrene-butadiene latex (DL966, commercially available from The Dow Chemical Company, Midland, Michigan, USA), dispersed in water at 50% solids.
Latex (B): Carboxylated styrene-butadiene latex (DL980 commercially available from Dow Chemical Company, Midland, Michigan, USA), dispersed in water at 50% solids.
PVOH: 15% solution of low molecular weight synthetic polyvinyl alcohol (MOWIOL 6/98, commercially available from Clariant AG, Basel, Switzerland).
Surfactant: An aqueous solution of sodium dialkylsulfosuccinate (AEROSOL OT, commercially available from Cyanamid, Wayne, NJ, USA), 75% solids.
PE dispersion (A): an anionic dispersion in which an ethylene acrylic acid copolymer having a minimum film forming temperature of 26 ° C. and a Tg of 4 ° C. is dispersed in water (TECHSEAL E-799 / 35 commercially available from Trub Chemie, Ramsen, Switzerland) ), 35% solids.
PE dispersion (B): Dispersion in which ethylene vinyl alcohol copolymer is dispersed in water (EXCEVAL AQ 4005, commercially available from Zwijndrecht, EVAL Europe, Belgium, this product is sent as a dry powder and the solution is made on a coater) , Dispersed in water with a solid content of 15%.
Brightener: A fluorescent brightener derived from diamino-stilbene disulfonic acid (TINOPAL ABP / Z, commercially available from Ciba Specialty Chemicals Inc., Basel, Switzerland).

Application Procedure The formulation was applied on paper running at 500 m / min by the following procedure. A multilayer slide die type curtain coater made by Troller Schweizer Engineering (Murgenthal, TSE, Switzerland) was used. The curtain applicator was equipped with a small amount of watered edge guide and a vacuum suction device that removed the edge lubricating water from the bottom of the edge guide just above the edge of the coated paper. Furthermore, the curtain coater has a vacuum suction device for removing the interfacial surface air from the paper support upstream of the curtain impingement zone. The height of the curtain was 300 mm. Prior to use, the paint formulation was degassed to remove bubbles.

Example 1
The above components were mixed in the amounts shown in Table 1 and applied in the coating amounts shown in Table 1.

  The pH of the color coating formulation was adjusted to the values shown in Table 1 by adding NaOH solution (10%). Water was added as necessary to adjust the solid content of the formulation.

  A pigment layer (slot 1) was applied onto the paper. This formulation contained a large amount of a low Tg latex that reliably provided good crack resistance to the barrier paper and also contained a water soluble polymer to form the interface layer. The next layer (slot 2) contained an ethylene acrylic acid dispersion forming a barrier layer against water and water vapor. The next layer (slot 3) contained a pigment layer containing a large amount of low Tg latex that ensured the barrier paper good crack resistance. The next layer (slot 4) contained a water soluble ethylene vinyl alcohol copolymer to provide good resistance to grease and oil. The top layer (slot 5) was a pigment layer containing an optical brightener in the formulation to form a good printed surface.

Example 2
The method of Example 1 was repeated except that the intermediate coating layer (slot 3 in Table 1) was removed and the coating amounts of the barrier paint layer and the uppermost printing layer were adjusted as shown in Table 2.

Example 3
The method of Example 2 was repeated except that the coating amount of slot 1 was reduced to 2 g / m ² and the coating amounts of barrier layer slot 2 and slot 3 were increased to 5 and 2.5 g / m ² respectively.

  Table 3 lists the bumps, MVTRs, kits and hot oil properties of each example.

  The results in Table 3 show that it is possible to have an improved water barrier and oil / grease barrier combination from a multilayer curtain.

  Table 4 summarizes the properties of the coated paper of each example.

The results in Table 4 show that a multilayer curtain with a barrier layer and a top printed layer gives satisfactory coated paper properties compared to current commercial paper.
Embodiments of the present invention will be exemplified below as items 1 to 28.
1. a) Composite multilayer comprising at least two layers providing at least two different barrier functions selected from the group consisting of oil and / or grease barrier functionality, water vapor barrier functionality, water resistance functionality, and oxygen barrier functionality Forming a free-flowing curtain; and b) contacting the curtain with a continuous web support so that an oil and / or grease barrier layer is present in the multi-layer curtain when the flat test is at least 5 When having a kit value and a water vapor barrier layer is present in the multilayer curtain, the water vapor transmission rate is less than 50 g / m ² / day (relative humidity 50%, 23 ° C.), and the water resistant layer is in the multilayer curtain. when present has a 10 minute Cobb value of less than 20 g / m ^2, if the oxygen barrier layer is present in the multilayer curtain 20 cm ³ / m ² / day / bar (1 atm, 23 ° C., a relative humidity of 90%) of a coated substrate having an oxygen transmission of less than method of manufacturing an coated substrate comprising a.
2. A method according to item 1, characterized in that the free-flowing curtain of step a) comprises an additional top layer providing printability.
3. Process according to any one of the preceding items, characterized in that when an oil and / or grease barrier layer is present in step a), the coated support has a kit value of at least 8 in the flat test.
4). Any of the above items, characterized in that when a water vapor barrier layer is present in step a), the coated support has a water vapor transmission rate of less than 40 g / m ² / day (relative humidity 50%, 23 ° C.). The method according to any one of the above.
5. If the water barrier layer is present in step a), coated substrate, characterized in that it has a 10 minute Cobb value of less than 12 g / m ^2, The method according to any one of the preceding items.
6). If the oxygen barrier layer is present in step a), characterized in that it has coated substrate is, 150cm ³ / m ^2/24 hr / bar (1 atm, 23 ° C., the oxygen transmission rate of less than 90% RH) The method according to any one of the above items.
7). A method according to any one of the preceding items, wherein the multilayer curtain of step a) comprises an additional interfacial layer that is a layer in contact with the support.
8). Process according to any one of the preceding items, characterized in that the multilayer curtain of step a) comprises at least an additional layer providing crack resistance.
9. The method according to at least one of the layers of the multilayer curtain of step a), characterized by having a dry coating amount of less than 30 g / m ^2, any one of the above items.
10. The method according to the multilayer curtain of step a), characterized by having a dry coating amount of less than 60 g / m ^2, any one of the above items.
11. A method according to any one of the preceding items, wherein the multilayer curtain of step a) comprises at least 3 layers.
12 A method according to any one of the preceding items, wherein the multilayer curtain of step a) comprises at least one layer comprising at least one pigment.
13. The pigment is clay, kaolin, calcined clay, talc, calcium carbonate, laminar nanoparticles, high aspect ratio clay, titanium dioxide, satin white, synthetic polymer pigment, zinc oxide, barium sulfate, gypsum, synthetic magnesium oxide, silica, alumina trihydrate 13. Method according to item 12, characterized in that it is selected from the group consisting of salt, mica and diatomaceous earth.
14 At least one layer providing the barrier functionality of the multilayer curtain of step a) is ethylene acrylic acid copolymer, ethylene vinyl alcohol copolymer, polyurethane, epoxy resin, polyester, polyolefin, carboxylated styrene butadiene latex, carboxylated styrene acrylate latex, Polyvinylidene chloride, polyvinyl chloride, starch, protein, styrene-acrylic copolymer, styrene maleic anhydride copolymer, polyvinyl alcohol, polyvinyl acetate, carboxymethyl cellulose, silicone, wax, neoprene, polyhydroxy ether, lacquer, polylactic acid, polylactic acid copolymer , Polymers containing fluorine atoms, carboxylated styrene butadiene acrylonitrile copolymer Characterized in that it comprises at least one or more components selected from the group consisting of copolymers and mixtures thereof acrylonitrile such mer, The method according to any one of the above items.
15. Process according to any one of the preceding items, wherein at least one layer of the multilayer free-flowing curtain of step a) comprises at least one surfactant.
16. Process according to any one of the preceding items, wherein the multilayer free-flowing curtain of step a) has a solids content of at least 10% by weight.
17. Process according to any one of the preceding items, characterized in that the continuous web support in step b) is a base paper or paperboard.
18. Process according to any one of the preceding items, characterized in that the continuous web support of step b) is neither primed nor pre-calendered.
19. Process according to any one of the preceding items, characterized in that the continuous web support of step b) has a web speed of at least 200 m / min.
20. The method according to the continuous web substrate of step b), and having a basis weight i.e. basis weight of 30 to 400 g / m ^2, any one of the above items.
21. A coated support obtained by the method according to any one of the above items.
22. Item 22. The coated support according to item 21, wherein the coated support is coated paper or paperboard.
23. The multilayer curtain of step a) comprises at least one additional layer that provides at least one of sheet stiffness, sheet flexibility, peelability, adhesion, friction control, heat sealability and abrasion resistance The method according to any one of items 1 to 20.
24. a) at least two different barrier functionality selected from the group consisting of oil and / or grease barrier functionality, water vapor barrier functionality, water resistance functionality, aroma barrier functionality, organic solvent barrier functionality and oxygen barrier functionality A method of manufacturing a coated support comprising: forming a composite multilayer free-flowing curtain comprising at least two layers to be applied; and b) contacting the curtain with a continuous web support.
25. 25. A method according to any one of items 1 to 20, 23 and 24, wherein the curtain is formed by a slot die.
26. 25. A method according to any one of items 1 to 20, 23 and 24, wherein the curtain is formed by a slide die.
27. 27. A method according to any one of items 1 to 20 and 23 to 26, wherein at least one layer of the curtain comprises polyethylene oxide.
28. 28. A method according to any one of items 1 to 20 and 23 to 27, wherein the curtain comprises polyethylene oxide in its interface layer.

FIG. 2 is an explanatory cross-sectional view of a preferred curtain coating apparatus 1 having a slide nozzle arrangement 2 for discharging a plurality of flows 3 of a curtain layer to form a continuous multilayer curtain 4.

Claims (5)

a) Composite multilayer comprising at least two layers providing at least two different barrier functions selected from the group consisting of oil and / or grease barrier functionality, water vapor barrier functionality, water resistance functionality, and oxygen barrier functionality forming a free flowing curtain, and b) the curtain is brought into contact with a continuous web substrate, to obtain a coated substrate by its step,
The viscosity of each of the at least two layers is 100 mPa · s or more, and the running direction of the continuous web support is such that the curtain is in contact with the continuous web support. A method for producing a coated support, which is changed immediately before the region .   The process according to claim 1, characterized in that the continuous web support of step b) is neither primed nor pre-calendered.   The process according to claim 1 or 2, characterized in that the continuous web support of step b) has a web speed of at least 200 m / min.   The method according to claim 1, wherein the curtain is formed by a slide die.   The method according to claim 1, wherein at least one layer of the curtain comprises polyethylene oxide.

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