JP2020073753A - Heat-sealable barrier paper - Google Patents

Abstract

To provide development of a paper provided with water vapor barrier properties and thermal sealing properties during an online manufacture of paper.SOLUTION: The paper includes: a fiber base material; a precoated layer containing a binder, and a mixture of a plate filler having at least 15 shape factors and finer fillers, where, a dimension of the finer filler particle is less than 2 μm with respect to 80 mass% (as measured in accordance with the ISO 13317-3 sedigraph method); and at least one coating layer applied to the precoat layer. The paper has a water vapor permeability of up to 150 g/m/24 hr and preferably less than 100 g/m/24 hr as measured in accordance with ASTM F1249 under so-called tropical conditions of 38°C and 90% relative humidity.SELECTED DRAWING: None

Description

  The present invention relates to the field of wrapping paper.

Plastic films are widely used in flexible packaging because they have the water vapor barrier properties required for proper storage of perishable products or products with a limited shelf life.
Paper is a material made from fibers, generally cellulosic fibres, and thus of plant origin. They are of course porous and permeable to gases and cannot be used as such for this application.
However, it is known to combine paper with other substances (plastic, aluminum, etc.) in order to obtain the above-mentioned barrier properties required for packaging various products and especially perishable foods. In this case, the paper support is subjected to conversion operations, for example application of a coating layer made of polymer in dispersion, extrusion coating of molten polymer or plastic or aluminum film. Including a stack of. The cost of this paper-based composite with barrier properties is becoming high.
Document US 2 653 870 A describes a method of making wrapping paper.
Packaging materials made from online manufactured barrier papers are described in patent application WO 2011/056130. On-line production is understood to mean production using a single production means, which comprises all the elements needed to produce the paper.

However, the barrier levels proposed are limited to less restrictive measurement conditions (these are temperature, ie 25 ° C., 75% relative humidity). This barrier level is measured by water vapor transmission rate, a weak barrier means high water vapor transmission rate. In that document, "tropical" conditions (ie 38 ° C, 90% relative humidity) are much more severe than temperature conditions, and consequently the barriers measured under mild conditions are more It is known to be even lower.
The expression “barrier paper” is to be understood as meaning a non-porous paper comprising a fibrous substrate covered with one or more layers, which is Ingress of said water vapor into said packaging material in an amount which is sufficiently leak-proof and which may adversely affect the preservation of the product contained therein or the integrity of said product. Resist.

The present invention, 38 ° C. and of 90% relative humidity under a so-called tropical conditions, ASTM as measured according F1249 standard, higher even at 150g / m ^2/24 and preferably in 100g / m ^2/24 There is particular, but not exclusive, interest in water vapor barrier papers that have water vapor transmission rates less than an hour.
It is advantageous that the barrier paper is also heat-sealable, in order to allow the formation of the packaging material by sealing the paper against itself.
The production of heat-sealable paper comprises, for example, the step of layering a coating layer of heat-sealable polymer on a cellulosic support. Such a cover layer has a very strong tackiness when not dried, and to prevent the various turns of the paper reel from sticking together, the paper is wound. It must be able to dry completely before being applied.
The application of this coating layer is generally carried out off-line during one or more processing steps, which gives good coating properties and precludes excessive penetration of the coating layer into the fibrous support. , To gain from the paper at ambient temperature at the time of the coating, and to allow the reel width transit time in the oven to be adapted to speeds of the order of, for example, 200 m / min, resulting in exposure times to these heating means. Is sufficient to completely dry to the depth of the heat-sealable coating layer.

The documents US 2004/121079 A1, WO 2010/052571 A2, US 2014/113080 A1 and WO 2009/112255 A1 disclose paper processed offline.
Paper, which provides a barrier to water vapor and is optionally heat-sealable, is generally produced during the processing operation in the above prior art and conventionally has a coating layer of 10-30 g / m ² when dried. , The coating layer, using one of various coating means (air knife, reverse gravure, Meyer rod or bar or any other coating method), as one or more thicknesses, or It is deposited by applying one thick layer utilizing a flow coating.
Therefore, said off-line processing of said paper to give it a water vapor barrier and heat-sealing property is an additional step in the manufacture of said paper, which significantly increases its cost and which is a plastic film packaging. Restrict the development of paper in flexible packaging, which is advantageous for Therefore, there is an economical demand for improving the productivity in the production of heat-sealing paper having a water vapor barrier property.

The present invention relates to the development of paper that has been provided with a water vapor barrier and heat sealability during the on-line manufacture of paper. This barrier and heat sealable paper can be used to make packaging materials by sealing the paper to itself.
The heat-sealable layer and more generally any heat-sealable layer, or more generally, applied to the fibrous substrate, online or offline, independent of the way in which the heat-sealable layer is applied. We face the problem of facilitating the deposition of coating layers.
Generally, it is desirable that the coating layer not penetrate too deeply into the fibrous base material to reduce its amount applied to the paper when the layer is polymer based. Moreover, less penetration of the cover layer allows the barrier film to be manufactured more easily.
The use of Yankee cylinders is the first solution for reducing surface porosity.
The second option is to use a calendar prior to any processing of the paper.
Another option is to take measures to have a precoat layer present in order to reduce the porosity of the paper.
Another alternative is to combine one or the other of the above selection means.
Certain hydrophobic and highly film-forming latices can be used in forming the precoat layer.

However, the hydrophobicity of the precoat layer thus presents a question of wettability during application of the coating layer when the coating layer is aqueous, especially in the case of online processes using high speeds for the sheet. Can result in a completely non-uniform coating of the precoated fibrous substrate with the coating layer. Furthermore, the surface energy of the precoat layer must be sufficiently different from that of the coating layer, while following the well-known rules for wettability to reduce the risk of wet defects.
As a result, there remains a need to adequately address the problems associated with the applicability of the coating layer.
The present invention fulfills this need, according to one of the aspects of the present invention, thanks to the following papers: The paper is
・ Fiber base material;
A precoat layer containing a binder and a mixture of plate-like filler (s) and fiber (s) having a form factor of at least 15, especially finer filler (s), said finer layers The particle size of the filler is less than 2 μm, based on 80% by weight (measured according to the ISO 13317-3 SediGraph method);
-At least one coating layer applied to the precoat layer,
Hints, the paper is higher at 150g / m ^2/24 also and preferably less than at 100g / m ^2/24, the so-called tropical conditions of 38 ° C and 90% relative humidity, ASTM F1249 standard Water vapor transmission rate, measured according to.

The presence of platy fillers having a form factor of at least 15 and finer, especially non-platy, granular fillers in the precoat layer according to this aspect of the invention is independent of the hydrophobic or non-hydrophobic nature of the binder. It is possible to achieve relatively high barrier levels, the size of the particles of the finer filler being less than 2 μm (measured according to ISO 13317-3 sedgraph method), relative to 80% by weight.
The plate-like filler is, for example, as taught by Documents: Imerys Technical Guide, Pigments for Paper, May 2008, due to the tortuosity of the filler, Helps increase its barrier effect. The presence of at least one finer, especially non-platy, particulate filler according to this aspect of the invention enhances this effect. One tentative explanation is that the filler further impedes the movement of water molecules by sliding between the plate-like particles, especially around the plate-like particles. Document: WO 2009/117040 A1 discloses plate fillers made of clay.
Due to the barrier effect associated with the particular selection of the filler present in the precoat layer, there is greater freedom as to the nature of the binder used.
It is thus possible, inter alia, to use any papermaking binder which does not have specific barrier properties, which has the dual advantage of low water vapor transmission rate for the precoat layer and good wettability for the coating layer. Allows you to get the benefits.

The invention makes it possible to give the precoat layer an enhanced barrier effect, which makes it possible to reduce the amount of coating layer to be applied or, for an equivalent amount of coating layer, It allows the barrier level of the paper to be further increased, which may prove useful for papers which must be leaktight to water vapor. The reduction in the amount of coating layer required due to this higher barrier capacity of the precoated paper facilitates its drying and also makes it easier to coat this layer during on-line manufacture of the paper. there is a possibility.
The paper of the present invention is preferably produced on a papermaking machine from a fibrous base material consisting of cellulosic fibers and optionally synthetic fibers.
The cellulose fibers are generally a mixture of short fibers and long fibers.
Additives such as sizing agents, wet strength agents, retention agents or defoamers can be added.
Similarly, the papers mentioned above can likewise contain fillers for papermaking, such as titanium dioxide, kaolin, calcium carbonate and talc, among others.
The paper is preferably packaging paper.

Another object of the present invention, suitable for making barrier paper according to the present invention, as defined above, according to the above criteria, at 150g / m ^2/24 be higher and preferably 100 g / m ² It is on pre-coated paper with a water vapor transmission rate of less than / 24 hours. The precoated paper may not be calendared.
Another subject of the invention is a precoating composition for producing the paper according to the invention, which comprises a binder in the form of a latex and a plate-like filler and a finer filler with a form factor of at least 15. A dispersion consisting of a mixture of (one or more), wherein the size of the finer filler particles is less than 2 μm with respect to 80% by weight.
Another subject of the invention is a packaging material according to the invention, in particular containing a paper which is heat-sealed to itself, which packaging material comprises, for example, a food product.
Another subject of the invention is a method for producing a paper according to the invention, in which a precoat treating composition as defined above is applied to a fibrous substrate.

Precoat Layer The precoat layer may be the same as the coating layer or may be a pigment layer as defined below.
The precoat layer preferably consists of a mixture of at least one latex and fillers, which are also often called "pigments".
Document: US 4 018 647 A describes an example of latex.
The latex according to the present invention preferably has a Tg (glass transition temperature) measured according to the ASTM E1356 standard of 25 ° C or lower and more preferably 10 ° C or lower. The latex may be selected from latexes having the following chemical properties: styrene-butadiene, styrene-acrylic, acrylic, butyl acrylate, butyl acrylate / styrene / acrylonitrile, etc., and more specifically styrene-butadiene emulsion. ..
The amount of the latex is preferably at least 15 parts, preferably at least or even more than 25 parts per 100 parts filler, and more preferably 30 parts, per 100 parts filler, when dry. It is a department.
The filler is preferably composed of a mixture of plate-like fillers and finer, especially non-plate-like fillers.
The platy filler is a particle in the form of lamellae having a shape factor (ratio between maximum length and thickness) of at least 40, more preferably at least 40 and even more preferably at least 60. Is.

The precoat layer comprises a binder and a mixture of plate-like fillers and finer fillers, especially non-plate-like fillers, having a form factor of at least 15, the size of the finer filler particles being 80% by weight. For less than 2 μm (measured according to the ISO 13317-3 sedgraph method).
In order to include a mixture of plate-like filler and finer filler, the size of the particles of the finer filler is less than 2 μm with respect to 80% by weight, the size of the particles of the plate-like filler, for example, It can be equal to or greater than 2 μm for 80% by weight. According to another example, less than 80% by weight of the plate-like particles may be less than 2 μm.
In other words, in order to include a finer filler than the plate-like filler, the finer filler, according to the first example, than the particle size of the plate-like filler in the equivalent mass distribution (weight distribution) Can also have a small granularity. According to the second example, the particles can have a greater mass distribution for particles of the same size than that of the plate-like filler.
The finer fillers mentioned above can be chosen from all other pigments used in papermaking which meet the required size requirements.
The ratio of the plate-like filler to the total filler can be varied in the range of 10% to 90%, preferably 40% to 90%, and even more preferably 60% to 90%.

The plate-like filler can be selected from, for example, kaolin and talc, and mixtures thereof.
30% to 80% by weight of the plate-like particles can be of a size equal to or less than 2 μm (measured according to the ISO 13317-3 sedgraph method).
The particles of the plate-like filler are particularly oriented substantially parallel to the surface of the support.
The finer filler particles can be selected from calcium carbonate, barium sulfate, silica, titanium dioxide and mixtures thereof. They are characterized by a particle size of less than 2 μm, relative to 80% by weight, as measured according to the ISO 13317-3 sedgraph method.
Similarly, the finer fillers mentioned above have any fineness, in particular 95% by weight, of less than 2 μm, a particle size measured according to the ISO 13317-3 sedgraph method, of any other containing kaolin. It can be selected from pigments.
The binder is preferably selected from the abovementioned latices, but it is also possible to use other binders or auxiliary binders such as PVOH, starch, CMC and the like. The binder can include polymers with chemical properties that are not present in the coating layer.

Coating Layer The polymer used to obtain the vapor barrier and heat sealability is preferably selected from PVdC (polyvinylidene chloride) or acrylic based polymers or copolymers.
These polymers are applied as pure polymers or mixtures with fillers. The term "pure" is understood to mean devoid of particulate filler. Other products, such as pH modifiers, rheology (e.g. viscosifying) rheological agents, defoamers, wettability agents, etc. are optionally added to the dispersion of the polymer. be able to.
The use of fillers in the coating layer can help to reduce the risk of reel turns sticking to each other, among others.

Manufacture Preferably, the coating layer is applied online.
The invention makes it possible to achieve good water vapor barrier levels for coating masses which do not exceed 10 g / m ² when dried.
Despite the relatively high running speed of the paper, such as about 400 m / min, imposed by an industrial papermaking machine, online application of the composition for forming the heat-sealable coating layer is This is possible, provided that sufficient drying capacity is used to dry the layer prior to the layer winding operation. In particular, the relatively low mass of the coating layer facilitates the on-line drying, while providing sufficient barrier properties.
The online process allows for increased productivity by eliminating handling operations associated with the offline processing.
After drying the fibrous base material, the paper sheet can be transferred to a Yankee cylinder to improve the surface finish of the sheet and consequently the distribution of its first layer.
The sheet may then be processed in a size press or any other device of similar type. In order to avoid excessive penetration of the precoat layer into the fibrous support, the pigment composition can be used in advance to perform "pore filling".
This pore-filling composition comprises 20 parts by weight of the filler when dry, up to 20 parts of binder when dry, for example a latex having the chemical properties of styrene-butadiene, and the dry pigment. Up to a portion of auxiliary binders such as starch and the like can be included.
The composition preferably contains a filler, which generally has a size of less than 2 μm. These fillers can be chosen, inter alia, from kaolin or calcium carbonate or mixtures thereof.

The precoat layer is applied to the support thus treated using any of the coating techniques that may be encountered on a papermaking machine. This can be knife coating, gravure coating, reverse gravure coating or Mayer rod coating, among others. The precoat layer is preferably deposited with a dry layer weight of between 4 and 12 g / m ² .
The precoat layer is then dried, without contact, with one or more infrared ovens and / or one or more hot air ovens.
It is not necessary to have a very high level of smoothness prior to applying the coating layer. A Bekk level of 150 seconds is sufficient (measured according to ISO 5627 standards).
The water vapor barrier and heat sealable coating layer is applied by a coating method using any of the coating techniques that may be encountered in a papermaking machine. This can be, for example, knife coating, gravure coating, reverse gravure coating or Mayer rod coating. The coating layer is preferably deposited with a dry layer weight of at most 10 g / m ² .
This coating layer is then satisfactorily used using one or more infrared ovens and / or one or more hot air ovens to prevent that turn on the take-up reel from sticking. To be dried.
Coating can be performed on the opposite side to enhance the barrier properties and / or provide other functionality such as printability, curl correction and the like.
The paper thus produced can optionally be calendered on-line to reduce its surface roughness prior to its winding.
The final basis weight of the paper may be between 45 and 200 g / m ² .
38 ° C., at 90% relative humidity, barrier properties against water vapor measured according to ASTM F1249 standard, 150 g / m ² / less than 24 hours, and preferably less than at 100g / m ^2/24.

Example 1:
A fibrous support having a basis weight of 55 g / m ² is produced on a papermaking machine operating at 400 m / min. The papermaking machine comprises a Yankee cylinder arranged in front of the size press.
The fibrous support is first polished, and then 100 dry parts of Amazon Premium type kaolin (Cadam) and a dry film having a ratio of 20 dry parts to the dry kaolin. (Merifilm) 104 starch (Tate & Lyle) and a mixture of a latex of the DL950 type (Dow) (Dow), using a pore-filling pigment composition, the support of the support by size press. Process both sides online. Overall, the treatment applied is 5 g / m ² when dry.
This is then mixed using a Mayer rod coater with a mixture of plate-like filler and finer particulate filler and a latex with styrene-butadiene type chemistry at Tg = 7 ° C (from Dow Chemical). It is coated with a precoat formulation containing DL950) and dried without contact in an infrared oven and then in a hot air oven. It is then wound onto a reel without any other treatment. The dry weight of this applied precoat layer is 7 g / m ² and its formulation is given in the table below:

The particle size of 97% by mass according to Amazon Premium, measured according to the ISO 13317-3 sedgraph method, is less than 2 μm.
The form factor of Kapim NP particles is 28.
The water vapor barrier properties are measured by a Mocon Permatran 3/61 apparatus according to the ASTM F1249 standard at 38 ° C. and 90% relative humidity to determine the barrier contribution for this precoat layer. This is measured at at ^{334 ± 13g / m 2/24} . After applying the coating layer, the barrier property of less than at 150g / m ^2/24 is obtained.

Example 2:
The fibrous support is first glazing, and then 100 dry parts of Amazon Premium type kaolin (Cadam) and a ratio of 20 dry parts to the dry kaolin (Merifilm). 104 On-line treatment of both sides of the support by size press with a pore-filling pigment composition comprising a mixture of starch (Tate & Lyle) and DL950 type latex (Dow). To do. Overall, the treatment applied is 5 g / m ² when dry.
This is then mixed using a Mayer rod coater with a mixture of plate-like filler and finer particulate filler and a latex with styrene-butadiene type chemistry at Tg = 7 ° C (from Dow Chemical). It is coated with a formulation containing DL950) and dried without contact in an infrared oven and then in a hot air oven. It is then wound onto a reel without any other treatment. The dry weight of this applied precoat layer is 7 g / m ² and its formulation is given in the table below:

The particle size to 95% by weight according to Hydrocarb 95, measured according to the ISO 13317-3 sedgraph method, is less than 2 μm.
The barrier properties to water vapor are measured with a Mocon Permatran 3/61 apparatus according to ASTM F1249 at 38 ° C. and 90% relative humidity to determine the barrier contribution for this precoat layer. It is measured at 315 ± 9g / m ² / 24h. After applying the coating layer, the barrier property of less than at 150g / m ^2/24 is obtained.

Example 3:
Paper is produced online under the same conditions as in Example 1. However, following the deposition of the precoat layer, it was applied online with a coating layer consisting of a dispersion of PVdC copolymer (Diofan A297 from Solvay) and infrared heating without contact. Dry in oven and then in hot air oven. It was then wound onto a reel without any other treatment, but no coupling between turns was observed. The dry weight of this coating layer is 6.5 g / m ² .
The barrier properties against water vapor are measured at 38 ° C. and 90% relative humidity according to the ASTM F1249 standard by means of the Mokon Permatran 3/61 instrument. It is measured at 21.0 ± 2.4 g / m ² / 24h.
Then, the sealing property of the above-mentioned paper was measured on a heat-sealing device for a laboratory at 110 ° C. under about 0.3 MPa (3 bar) for 0.5 seconds, and the surface covered with the coating layer was itself sealed. Simulate by connecting to. The force required to separate the paper bound to the sample with a width of 15 mm is then subsequently measured according to the Tappi T540 standard at a speed of 100 mm / min under an angle of 90 degrees.
A sealing force of 3.5 N / 15 mm is obtained.
The invention is not limited to the described embodiments.

In summary, the present invention can have one or more of the following advantageous features:
The mass of the coating layer does not exceed 10 g / m ² when dried, particularly strictly less than 10 g / m ² ;
The coating layer comprises or is composed of a heat-sealable polymer;
The plate filler and the finer filler have the same properties;
The form factor of the plate-like filler particles is at least 40, more preferably at least 60;
The finer filler is a non-planar filler;
The finer filler is a plate-like filler;
The finer filler has a particle size of less than 2 μm, measured according to ISO 13317-3 sedgraph method, for 95% by weight;
-The plate-like filler is an inorganic filler;
The finer filler is an inorganic filler;
The tabular filler is selected from kaolin and talc and mixtures thereof;
The finer filler is selected from kaolin, calcium carbonate, barium sulphate, silica, titanium dioxide and mixtures thereof;
The finer filler is selected from kaolin;
The dry mass of the plate-like filler is between 3% and 58% of the total dry mass of the precoat layer, the mass of the plate-like filler preferably being greater than the value of the finer filler;

The dry mass of the finer filler is between 3% and 58% of the total dry mass of the precoat layer;
The ratio of the plate-shaped filler expressed in dry mass to the whole filler expressed in dry mass is between 10% and 90%, preferably between 40% and 90%, and even more preferably Between 60% and 90%;
The binder has a glass transition temperature Tg of less than or equal to 25 ° C, and more preferably less than or equal to 10 ° C;
The binder is selected from styrene-butadiene, styrene-acrylic, acrylic, butyl acrylate, latex with butyl acrylate / styrene / acrylonitrile chemistry and mixtures thereof;
The binder is selected from a latex with styrene-butadiene chemistry;
The binder is introduced in latex form;
The precoat layer comprises at least 15 parts, and preferably greater than 25, and better still 30 parts of dry binder, based on the weight of the dry filler (100 parts);
The binder comprises a polymer with chemical properties not present in the coating layer;
The coating layer is substantially free of fillers;
The coating layer is the only layer overlying the precoat layer;
The coating layer comprises one or more polymers selected from PVdC-based or styrene-acrylic-based copolymers and mixtures thereof;
The amount of said precoat layer is less than or equal to 12 g / m ² on a dry weight basis;
The paper comprises a printing layer on the side of the support opposite to the side bearing the precoat layer and the coating layer;
The support has two identical precoat layers on its opposite sides;

The support has on its opposite surface two precoat layers with different properties;
A pore-filling composition is applied to the support, and the precoat layer is applied to the pore-filling composition, the pore-filling composition being preferably by size press or film press Applied;
The basis weight of the fibrous base material lies between 25 and 180 g / m ² .
The paper can be heat-sealed under about 0.3 MPa (3 bar) for 0.5 seconds, especially at 90 ° C., if the sealing is done with hot clamps;
Water vapor permeability of the barrier sheet is less than at 100g / m ^2/24;
Between 30% and 80% by weight of plate-like particles having a size equal to or less than 2 μm (measured according to ISO 13317-3 sedgraph method);
・ This paper is a vertical packaging machine of VFFS (Vertical Form, Fill and Seal) type, 40 bags / min along the longitudinal sealing line of 330 mm / bag. May be heat-sealed at equal or greater manufacturing rates, especially to itself;
The paper, according to the Tappi T540 standard, under an angle of 90 degrees, if the sealing is performed with hot clamps for 0.5 seconds under about 0.3 MPa (3 bar), Can be heat sealed to itself with a sealing force equal to or greater than 2N / 15mm as measured at a speed of 100mm / min;
The temperature of the fibrous substrate during application of the precoat layer is equal to or above 50 ° C;
The temperature of the fibrous base material during application of the coating layer is equal to or above 70 ° C .; the final basis weight of the paper lies between 45 and 200 g / m ² .
The expression "comprising a" is synonymous with "comprising at least one."

Preferred embodiments of the present invention are as follows.
[1] a fiber base material,
A precoat layer comprising a binder and a mixture of a plate-like filler having a form factor of at least 15 and a finer filler, in particular a non-plate-like filler, wherein the size of the finer filler particles is 80% by mass. On the other hand, a precoat layer having a thickness of less than 2 μm (measured according to ISO 13317-3 sedgraph method),
At least one coating layer applied to the precoat layer;
A paper containing, in 38 ° C. and 90% relative humidity as measured according to ASTM F1249 standards in the so-called tropical conditions, up to 150g / m ^2/24 hours and preferably less than at 100g / m ^2/24 Paper with water vapor transmission rate.
[2] weight of the coating layer is not more than 10 g / m ² when dry, particularly, is strictly less than 10 g / m ^2, the paper according to the above [1].
[3] The paper according to [2], wherein the coating layer contains a heat-sealing polymer or is further composed of a heat-sealing polymer.
[4] The paper according to [1] or [2], wherein the plate-like filler and the finer filler have the same properties.
[5] The paper according to any one of [1] to [4], wherein the shape factor of the plate-like filler particles is at least 40, more preferably at least 60.
[6] In any one of the above [1] to [5], the finer filler has a particle size of less than 2 μm measured according to ISO 13317-3 sedgraph method, relative to 95% by mass. Written paper.
[7] The paper according to any one of [1] to [6], wherein the plate-like filler is an inorganic filler.
[8] The paper according to any one of [1] to [7], wherein the finer filler is an inorganic filler.
[9] The paper according to any one of [1] to [8], wherein the plate-like filler is selected from kaolin, talc, and a mixture thereof.
[10] The paper according to any one of [1] to [9], wherein the finer filler is selected from kaolin, calcium carbonate, barium sulfate, silica, titanium dioxide and mixtures thereof.
[11] The paper according to any one of [1] to [10], wherein the finer filler is selected from kaolin.
[12] The dry mass of the plate-like filler is 3% to 58% of the total dry mass of the precoat layer, and the mass of the plate-like filler is preferably larger than the mass of the finer filler, The paper according to any one of [1] to [11].
[13] The paper according to any one of [1] to [12], wherein the dry mass of the finer filler is 3% to 58% of the total dry mass of the precoat layer.
[14] The ratio of the plate-shaped filler represented by dry mass to the total of the filler represented by dry mass is 10% to 90%, preferably 40% to 90% and more preferably 60% to. The paper according to any one of [1] to [13] above, which is 90%.
[15] The paper according to any one of [1] to [14], wherein the binder has a glass transition temperature Tg of 25 ° C or lower and more preferably less than 10 ° C.
[16] [1] to [15], wherein the binder is selected from styrene-butadiene, styrene-acryl, acryl, butyl acrylate, latex having butyl acrylate / styrene / acrylonitrile chemistry, and mixtures thereof. ] The paper according to any one of [1].
[17] The paper according to any one of [1] to [16], wherein the binder is selected from a latex having a chemical property of styrene-butadiene.
[18] The paper according to any one of [1] to [17], wherein the binder is introduced in a latex form.
[19] The precoat layer contains at least 15 parts, and preferably more than 25 parts, and more preferably 30 parts, of a binder, based on the mass of the filler when dried (100 parts). The paper according to any one of 1] to [18].
[20] The paper according to any one of [1] to [19], wherein the binder contains a polymer having a chemical property that is not present in the coating layer.
[21] The paper according to any one of the above [1] to [20], wherein the coating layer contains substantially no filler.
[22] The paper according to any one of [1] to [21], wherein the coating layer is the only layer that covers the precoat layer.
[23] Any of [1] to [22] above, wherein the coating layer comprises one or more polymers selected from PVdC-based copolymers or styrene-acrylic-based copolymers and mixtures thereof. The paper according to item 1.
[24] The paper according to any one of [1] to [23], wherein the amount of the precoat layer is 12 g / m ² or less in dry mass.
[25] The paper according to any one of [1] to [24] above, which includes a printing layer on a surface of the base material that faces the surface having the precoat layer and the coating layer.
[26] The paper according to any one of [1] to [25], wherein the base material has two identical precoat layers on opposite surfaces thereof.
[27] The paper according to any one of [1] to [25], wherein the base material has two precoat layers having different properties on the opposite surfaces thereof.
[28] A pore-filling composition is applied to the substrate, and the precoat layer is applied to the pore-filling composition, and the pore-filling composition is preferably a size press or The paper according to any one of [1] to [27], which is applied by a film press.
[29] The paper according to any one of [1] to [28], wherein the fiber base material has a basis weight of 25 to 180 g / m ² .
[30] The above-mentioned [1] to [30], wherein the paper has a heat-sealing property, particularly when the sealing is carried out by hot clamping at 0.3 MPa (3 bar) for 0.5 seconds, starting from 90 ° C. The paper according to any one of [29].
[31] The paper according to any one of [1] to [30], wherein the final basis weight of the paper is 45 to 200 g / m ² .
[32] A precoated paper suitable for producing the paper according to any one of [1] to [31], which has a maximum of 150 g / m according to ASTM F1249 standard at 38 ° C. and 90% relative humidity. ^2:00 / 24 and preferably has a water vapor transmission rate of less than at 100 g / m ^2/24, precoating treatment paper.
[33] The precoated paper according to [32], which is not calendared.
[34] A packaging material containing the paper according to any one of [1] to [33].
[35] The packaging material according to [34], wherein the paper is heat-sealed to itself.
[36] The packaging material according to any one of [34] and [35], which includes a food product.
[37] The method for producing paper according to any one of [1] to [33], wherein the composition is applied to a fiber base material, and the composition is at least a binder in a latex form. A method comprising a plate-like filler having a shape factor of 15 and a dispersion of a mixture of finer fillers, wherein the size of the finer filler particles is less than 2 μm, relative to 80% by weight.

Claims (37)

A fiber substrate,
A precoat layer comprising a binder and a mixture of a plate-like filler having a form factor of at least 15 and a finer filler, wherein the size of the finer filler particles is less than 2 μm with respect to 80% by mass. A precoat layer (measured according to ISO 13317-3 sedgraph method);
At least one coating layer applied to said precoat layer, comprising a heat-sealable polymer;
A heat sealable paper containing, in the so-called tropical conditions of 38 ° C. and 90% relative humidity as measured in accordance with ASTM F1249 standard, has a water vapor transmission rate of at 150g / m ^2/24 at maximum, Heat sealable paper. The heat-sealing paper according to claim 1, wherein the weight of the coating layer does not exceed 10 g / m ² when dried.   The heat-sealing paper according to claim 1, wherein the coating layer is composed of a heat-sealing polymer.   The heat-sealing paper according to claim 1, wherein the plate-like filler and the finer filler have the same properties.   The heat-sealing paper according to any one of claims 1 to 4, wherein the form factor of the plate-like filler particles is at least 40.   The heat-sealing property according to any one of claims 1 to 5, wherein the finer filler has a particle size of less than 2 µm measured according to ISO 13317-3 sedgraph method with respect to 95% by mass. Paper.   The heat-sealing paper according to any one of claims 1 to 6, wherein the plate-like filler is an inorganic filler.   The heat-sealing paper according to any one of claims 1 to 7, wherein the finer filler is an inorganic filler.   The heat-sealing paper according to any one of claims 1 to 8, wherein the plate-like filler is selected from kaolin, talc, and a mixture thereof.   10. The heat-sealable paper according to any one of claims 1-9, wherein the finer filler is selected from kaolin, calcium carbonate, barium sulfate, silica, titanium dioxide and mixtures thereof.   The heat-sealing paper according to any one of claims 1 to 10, wherein the finer filler is selected from kaolin.   The heat-sealing paper according to any one of claims 1 to 11, wherein a dry mass of the plate-like filler is 3% to 58% of a total dry mass of the precoat layer.   The heat-sealing paper according to any one of claims 1 to 12, wherein a dry mass of the finer filler is 3% to 58% of a total dry mass of the precoat layer.   The heat sealing according to any one of claims 1 to 13, wherein a ratio of the plate-like filler expressed in dry mass is 10% to 90% with respect to the total of the filler expressed in dry mass. Sex paper. The heat-sealing paper according to any one of claims 1 to 14, wherein the binder has a glass transition temperature T _g of 25 ° C or lower.   16. The binder of claim 1, wherein the binder is selected from styrene-butadiene, styrene-acrylic, acrylic, butyl acrylate, latex having butyl acrylate / styrene / acrylonitrile chemistry, and mixtures thereof. The heat-sealing paper according to 1.   17. The heat-sealable paper according to claim 1, wherein the binder is selected from a latex having a styrene-butadiene chemistry.   The heat-sealing paper according to any one of claims 1 to 17, wherein the binder is introduced in a latex form.   The heat-sealing paper according to any one of claims 1 to 18, wherein the precoat layer contains at least 15 parts by weight of a binder when dried with respect to a mass (100 parts) of a filler when dried.   20. The heat-sealable paper according to any one of claims 1 to 19, wherein the binder comprises a polymer having a chemical property that is not present in the coating layer.   The heat-sealing paper according to any one of claims 1 to 20, wherein the coating layer contains substantially no filler.   The heat-sealing paper according to any one of claims 1 to 21, wherein the coating layer is the only layer covering the precoat layer.   23. The heat according to any one of claims 1-22, wherein the coating layer comprises one or more polymers selected from PVdC based copolymers or styrene-acrylic based copolymers and mixtures thereof. Sealing paper. The heat-sealing paper according to any one of claims 1 to 23, wherein the amount of the precoat layer is 12 g / m ² or less in dry mass.   The heat-sealing paper according to any one of claims 1 to 24, comprising a printing layer on a surface of the base material that faces a surface having the precoat layer and the coating layer.   26. The heat-sealable paper according to any one of claims 1 to 25, wherein the substrate has two identical precoat layers on opposite sides thereof.   The heat-sealing paper according to any one of claims 1 to 25, wherein the base material has two precoat layers having different properties on the opposite surfaces thereof.   28. The heat sealing of any of claims 1-27, wherein a pore filling composition is applied to the substrate and the precoat layer is applied to the pore filling composition. Sex paper. The heat-sealing paper according to any one of claims 1 to 28, wherein a basis weight of the fiber base material is 25 to 180 g / m ² .   The heat-sealing paper according to any one of claims 1 to 29, which is heat-sealing when the sealing is performed by hot clamping at 0.3 MPa (3 bar) for 0.5 seconds. .. The heat-sealing paper according to any one of claims 1 to 30, wherein the final basis weight of the heat-sealing paper is 45 to 200 g / m ² . A precoated paper suitable for the manufacture of the heat-sealing paper according to any one of claims 1 to 31, having a maximum of 150 g / m ² according to the ASTM F1249 standard at 38 ° C and 90% relative humidity. A precoated paper having a water vapor transmission rate of / 24 hours.   33. The precoated paper of claim 32, which is not calendered.   A packaging material comprising the heat-sealing paper according to any one of claims 1 to 33.   35. The packaging material of claim 34, wherein the heat sealable paper is heat sealed to itself.   The packaging material according to any one of claims 34 and 35, comprising a food product.   34. A method of making a heat-sealing paper according to any one of claims 1-33, wherein the composition is applied to a fibrous base material, the composition comprising a binder in latex form and at least 15 parts. And a dispersion of a mixture of finer fillers having a form factor of, wherein the size of the finer filler particles is less than 2 μm with respect to 80% by weight.