CN117881546A

CN117881546A - Thermal recording material, method of decolorizing thermal recording material, fiber material mixture, method for producing recycled paper, and recycled paper

Info

Publication number: CN117881546A
Application number: CN202280056047.2A
Authority: CN
Inventors: U·布拉施; T·斯托林
Original assignee: Koehler Innovation and Technology GmbH
Current assignee: Koehler Innovation and Technology GmbH
Priority date: 2021-08-11
Filing date: 2022-08-11
Publication date: 2024-04-12
Also published as: DE102021133751A1

Abstract

The present invention relates to: a thermosensitive recording material, wherein the colored layer contains at least one dye that can be removed, especially in the waste paper recycling; a method for decolorizing a heat-sensitive recording material to obtain a fibrous material mixture, comprising the steps of providing a mixture of the heat-sensitive recording material and at least one additional paper, in particular at least one broke, and subsequently decolorizing the mixture in a deinking process to obtain a fibrous material mixture; a mixture of fibrous materials obtainable by this process; a method for preparing recycled paper comprising a fibrous material mixture by compacting and dewatering the fibrous material mixture; and a recycled paper obtainable by this method.

Description

Thermal recording material, method of decolorizing thermal recording material, fiber material mixture, method for producing recycled paper, and recycled paper

The present invention relates to a thermosensitive recording material, a method for decoloring a thermosensitive recording material to obtain a fibrous material mixture, a fibrous material mixture obtainable by the method, a method for producing recycled paper comprising the fibrous material mixture, and a recycled paper obtainable by the method.

Thermal recording materials are known in theory, and can be basically classified into two different types of thermal recording materials, particularly thermal recording materials for direct thermal printing:

type 1: a thermosensitive recording material for producing a printed image by a local thermochemical reaction in a coloring layer, for example, between a color contrast agent (e.g., leuco dye) and a color developer (e.g., bisphenol a or a phenol-free substitute). The coloring layer generally additionally contains a heat-sensitive solvent which melts under the action of heat (for example, a long-chain fatty alcohol, an amide, an ester or a carboxylic acid), so that a color reaction of the color contrast agent and the color developer can be achieved. In addition, the colored layer may contain a thermal sensitizer.

Type 2: a thermosensitive recording material for producing a printed image by: the underlying colored layer is made visible by local thermal action, for example by means of a direct thermal printer, to make the thermally sensitive cover layer transparent. These techniques are described or explained in different ways in the prior art and are achieved by partially different compositions, porosities and materials of the cover layers to obtain such thermosensitive recording materials, optimizing direct thermal printing and will be explained in detail below.

The following applies here:

1. the cover layer should cover the underlying colored layer as well as possible. This is essentially achieved by light scattering (scattering particles), and

2. light absorption.

2. The cover layer should have as high a contrast as possible with respect to the underlying colored layer in order to produce a print (e.g., white/black or blue/yellow) that is readable to the human eye and/or the machine (scanner).

3. The cover layer should be as thermally sensitive as possible so that it is made transparent by local thermal action, in particular by means of conventional direct thermal printing. The recording materials of type 1 and type 2 should be used as much as possible with conventional direct thermal printers and the print settings, in particular the printhead temperature and printer speed, are similar.

The present invention relates to the above type 2 thermosensitive recording material.

In US2011/172094A recording material is disclosed, comprising the following:

a) A carrier having a surface impregnated with a colorant or coated with a coating comprising a pigment or dye, and disposed thereon

b) A layer comprising polymeric particles having a core-shell structure and which when dried are hollow so as to scatter visible light, wherein the particles have an inner first polymeric shell having a Tg of 40 ℃ to 130 ℃ and an outer second polymeric shell having a Tg of-55 ℃ to 50 ℃, wherein the Tg of the outer polymeric shell is lower than the Tg of the inner polymeric shell.

In US2011/251060A thermal recording material is described, which consists of a colorant and a flexible carrier substrate, wherein the thermal recording material further consists of a thermal layer, wherein the thermal layer consists of a binder, a plurality of organic hollow sphere pigments and a thermal solvent, and wherein the thermal layer is arranged on the colorant. The thermosensitive layer may be provided with a barrier layer and a protective layer.

In WO 2012/145456 A1 a thermosensitive recording material optimized for conventional direct thermosensitive printing is described, which contains:

a) A carrier in the form of a planar structure, said carrier comprising at least one coloured surface, and arranged thereon

b) A layer comprising polymer particles having a core-shell structure, wherein the particles have an outer first polymer shell having a calculated Tg of 40 ℃ to 130 ℃, wherein the particles comprise at least one cavity and 1 to 90 wt% of an antireflective agent having a melting point of 45 ℃ to 200 ℃ relative to the weight of the polymer particles when the particles are dry

Wherein the colored surface has sufficient color density to visibly cut from the surface of a subsequent layer dispersed thereon, wherein the antireflective agent is an aromatic oxalate, an aromatic glycol ether, 1, 2-diphenoxyethane, dibenzyl oxalate, dibenzyl terephthalate, benzyl biphenyl, benzyl-2-naphthalene ether, diphenyl sulfone, m-terphenyl, p-benzyloxybenzoate, cyclohexanedimethanol benzoate, p-toluenesulfonamide, o-toluenesulfonamide, 2, 6-diisopropylnaphthalene, 4-diisopropylbiphenyl, erucamide, stearic acid amide, palmitic acid amide, or ethylene bisstearic acid amide.

In WO 2013/152287 A1 a thermosensitive recording material with a bilayer monoaxially oriented film is described, comprising a first layer comprising an opaque polymer based on beta-nucleated propylene and a second layer comprising a dark pigment.

In US2015/049152A thermosensitive recording material is described, comprising a thermosensitive layer arranged on a colored solid carrier substrate, wherein the thermosensitive layer comprises single-phase scattering polymer particles, wherein each polymer particle has a center, a surface, a refractive index at its center (different from the refractive index at its surface), and a continuous refractive index gradient, wherein the thermosensitive layer further comprises thermally deformable particles and a binder.

In EP 2993054/A1 a ribbon-shaped thermal recording material is described, which has at least one first layer and a second layer at least partially covering the first layer, wherein the first layer has concentrated coloring at least towards the second layer and the second layer has a hollow-body pigment which can be shaped like a word by a locally limited heat treatment, characterized in that the second layer has one or more fatty acids and one or more thermal sensitizers in addition to the hollow-body pigment.

In US2017/337851A recording material is disclosed, comprising:

a layer of release-liner-base material,

an optional layer of adhesive(s),

the base layer of the tag is provided with a layer of tags,

an insulating layer disposed on the label base layer,

an ink layer disposed on the barrier layer, wherein the ink layer comprises at least one color,

disposing a cover layer over the printed ink layer

A top coat layer disposed over the cover layer,

wherein the cover layer comprises a propylene-based composition comprising light scattering particles that render the cover layer opaque in a first state and transparent in a second state, wherein at least heat or pressure is applied from the printhead such that the cover layer transitions from the first state to the second state, thereby causing the at least one color of the ink layer to become visible through the cover layer.

In WO 2019/183471 A1 a recording medium is disclosed comprising a substrate, wherein the substrate relates to first scattering particles having a certain melting point, the first scattering particles comprising a first solid state light scattering layer, and the first light scattering layer being as close as possible to a multitude of second solid state scattering particles, wherein the second solid state scattering particles have a melting point which is lower than the first melting point of the second solid state scattering particles, and wherein the first light scattering layer is porous, and the second scattering particles are during solid melting, wherein the first solid state scattering particles are arranged to fill the space between the recording medium.

In WO 2019/219391 A1 a thermosensitive recording material is described, comprising a black or colored carrier substrate on at least one side and a thermally responsive layer on said at least one black or colored side of said carrier substrate, wherein said thermally responsive layer comprises nanoparticles of at least one cellulose ester.

In WO 2021/055719 A1 a thermal or pressure sensitive recording material is described comprising a layer formed of an opaque material, a coloured material arranged on a first side of the layer formed of an opaque material, wherein the layer formed of an opaque material covers the coloured material, wherein the opaque material comprises a number of non-regular and/or non-linear forms of opaque polymer particles in an opaque state, the polymer particles defining cavities therebetween and having different shapes and/or different sizes, and further wherein the opaque material is configured such that it changes from an opaque state to a transparent state upon application of a sufficiently high temperature and/or a sufficiently high pressure so as to expose the coloured material underneath the opaque material.

In WO 2021/062230 A1 a recording medium is disclosed comprising a substrate, a first light scattering layer carried by the substrate and comprising first scattering particles having a first melting point, and a plurality of second scattering particles in the vicinity of the first light scattering layer, wherein the second scattering particles have a second melting point lower than the first melting point, wherein the first light scattering layer is porous and the second scattering particles are arranged to fill the spaces between the first scattering particles upon melting, and wherein the first scattering particles comprise perforated particles.

All known thermosensitive recording materials need improvement, especially in terms of their handleability in waste paper recycling, when they should be additionally used as a raw material of white paper type (deinked commodity) of particularly high value.

Another aspect is then that these known thermosensitive recording materials are generally only suitable or allowed to come into contact with food if they do not have a negative effect on the food. It is therefore another object of the present invention to provide a thermosensitive recording material which is additionally suitable or permissible for contact with food according to the standards of ISEGA development, inc. Of Aschaffenburg (as defined in the specification) and which also satisfies, for example, the strictly prescribed index of thermosensitive paper for environmental protection using blue sky.

These objects are surprisingly achieved by a thermosensitive recording material according to claim 1.

Removal of dyes, especially in the recycling of waste paper, is also referred to as "deinking". Thus, suitable dyes that can be removed, especially in the recycling of waste paper, may also be referred to as "deinkable dyes". In theory, the term "deinking" is known to those skilled in the art as the removal of printing ink from paper. In the context of the present invention, the term "dye" always refers to a deinkable dye.

Such a thermosensitive recording material is particularly advantageous in its recyclability and thus its economy. In addition, such thermosensitive recording materials satisfy the standards of ISEGA development stock, inc, aschaffenburg (as defined in the specification) in terms of their suitability for foods and/or the prescribed index of thermosensitive paper for environmental protection using blue sky.

Numerous specific details are set forth below in order to provide a thorough understanding of the present subject matter. It will be apparent, however, to one skilled in the art that the present subject matter may be practiced and modified without these specific details.

If the features of different embodiments are not non-uniform, all features of one embodiment may be combined with the features of other embodiments.

The terminology used in the description of the invention is for the purpose of describing certain embodiments only and is not intended to be limiting of the subject matter. As used in this specification and in the claims, the singular forms "a", "an" and "the" are to be understood as also including the plural forms, provided that the context does not explicitly indicate otherwise. The opposite is also used, i.e., plural is inclusive of singular. It will also be understood that the term "and/or" as used herein refers to and includes all possible combinations of one or more of the associated listed elements. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification and in the claims, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

In the present specification and claims, the terms "comprises," "comprising," and/or "includes" may also mean "consisting of … …," that is, excluding the presence or addition of one or more other features, steps, operations, elements, components, and/or groups.

In the present description and claims, the term "containing (einschlie. Beta. Lich)" may also mean "exclusive (ausschlie. Beta. Lich)".

In the present specification, the mentioned brookfield smoothness (if not otherwise defined) is determined in accordance with DIN 53107 (2016).

According to a first aspect, the present invention relates to a thermosensitive recording material, which comprises:

the carrier material in the form of a strip,

a coloured layer on one side of the tape-like carrier material and a heat-sensitive layer on the coloured layer, such that the coloured layer is at least partially obscured,

wherein the heat-sensitive layer is designed such that it becomes transparent by local heat action, such that the coloring layer located thereunder becomes visible, characterized in that the coloring layer contains at least one dye that can be removed, in particular in the recycling of waste paper.

The tape carrier material is not limited in theory. In a preferred embodiment, the tape-like carrier material comprises paper, synthetic paper and/or plastic foil. The support material preferably has a content of from 30 to 100g/m ² In particular 40 to 80g/m ² Is a weight per unit area of (a).

The tape-shaped carrier material of the thermosensitive recording material according to the present invention includes at least one coloring layer, i.e., at least one black or colored surface, realized by applying the coloring layer. The term "colored face" is understood to mean a face having a different color than white or black. In other words, the thermosensitive recording material includes at least one face colored not white. Embodiments are also possible in which the at least one black or colored layer has a plurality of different colors (which may also be combined with black).

Other embodiments are also conceivable in which the tape-shaped carrier material itself is dyed.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that, after processing the thermosensitive recording material according to the inde method 11, the following score values are achieved according to the print product recyclability, deinking ability score (according to 2017, 1, 2 nd roll):

a) The brightness Y is at most 35 minutes,

b) The color coefficient a in the CIELAB system is at most 20 minutes,

c) Spot a in two different size categories a50 is at most 15 minutes and spot a in a250 is at most 10 minutes,

d) Degree of dye removal (printing ink removal) IE is at most 10 minutes, and

e) The filtrate became deep deltay for at most 10 minutes,

wherein the sum of all fractions is in the range from 0 to 100, preferably in the range from 51 to 70, particularly preferably in the range from 71 to 100, and/or preferably no individual fraction value is negative.

Preferably, the sum of all fractions is in the range from 0 to 50, preferably in the range from 51 to 70, particularly preferably in the range from 71 to 100.

It is particularly preferred that none of the individual fraction values is negative.

Very particularly preferably, the sum of all fractions is in the range from 0 to 50, preferably in the range from 51 to 70, particularly preferably in the range from 71 to 100, and no individual fraction value is negative.

In a preferred embodiment, the thermal recording material of the present invention is further characterized in that the at least one dye comprises at least one pigment and/or dye. The dyes herein may include inorganic or organic dyes or inorganic or organic pigments.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the at least one dye is selected from the group consisting of a dye capable of bleaching, a hydrophobic dye, a dye capable of hydrophobizing and/or a magnetic dye.

Such dyes are characterized by good deinking properties.

In the colored layer, the at least one dye is preferably contained in an amount of 2 to 50% by weight, particularly preferably 10 to 35% by weight, relative to the total solid content of the colored layer.

The amount is not applicable where the at least one dye includes or is carbon black. When the at least one dye includes or is carbon black, the carbon black is preferably contained in the colored layer in an amount of 24% by weight or less, preferably 19% by weight or less, relative to the total solid content of the colored layer. In the colored layer, carbon black is preferably contained in an amount of 2 to 24% by weight, preferably 2 to 19% by weight, particularly preferably 10 to 24% by weight or 10 to 19% by weight, relative to the total solid content of the colored layer.

In another embodiment, the colored layer contains carbon black in an amount of less than 2% by weight relative to all thermosensitive recording materials.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that said at least one removable dye, especially removable (deinkable) in the recycling of used paper, is selected from the group comprising:

carbon black pigments (in minor amounts of up to 24% by weight, preferably up to 19% by weight),

Alternative carbon black pigments, for example having different particle sizes, morphologies, primary/secondary particle compositions and/or surface chemistries,

organic dyes, in particular organic dyes capable of bleaching,

direct dyes (Direktfarbstoffe), also known as substantive dyes (Substivfarbstoffe),

-a reactive dye, which is a reactive dye,

disperse dyes (organic and water-insoluble),

pigment dyes, in particular disperse dyes,

iron oxide, fe ₃ O ₄ (magnetic),

sulfur dyes (e.g. Casssulfon, diresul black PFT fl.),

the activated carbon is present as a dispersion of the activated carbon,

metal complex dyes, in particular iron-based, such as iron gallate inks (iron (III) gallate, which can be produced, for example, from Fe (II) SO ₄ +gallic acid (or tannic acid) is prepared and then smeared under the action of oxygen in air to form iron (III) gallate,

the presence of graphite is a material of the type,

mica, in particular as a substitute for organic pigments,

carbon black pigments and dark pigments, such as in particular iron oxides, for example Fe ₃ O ₄ In a combination of (a) and (b),

biobased/food dyes, such as sepia black dyes, caramel colors or lignin based on hydrothermal treatment, for example Reforce X4500 from XILLIX GmbH of Oberkirch, germany,

printing inks for colouring (offset inks, (UV) flexo inks),

Charcoal/charcoal ash, and/or

Activated carbon/activated carbon ash.

They may be present individually or in any mixture.

Particularly preferred are substantive dyes, water-flexible dyes (Wasselfex ofarbstoffe), graphite, sulphur dyes such as Cassssulphur, iron gallate inks, inorganic and/or organic pigment dyes and/or iron oxides (Fe ₃ O ₄ ) Such as Bayferrox 306 or iron oxide black.

Preference is likewise given to carbon black pigments and dark pigments, such as in particular iron oxides, for example Fe ₃ O ₄ Is a combination of (a) and (b).

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the colored layer contains at least one binder.

As binders, preference is given to using water-soluble starches, starch derivatives, starch-based biological latices of the EcoSphere type, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gelatin, casein, partially or fully saponified polyvinyl alcohol, chemically modified polyvinyl alcohol, ethylene-vinyl alcohol copolymers, sodium polyacrylate, styrene-maleic anhydride copolymers, ethylene-maleic anhydride copolymers, styrene-butadiene copolymers, acrylamide- (meth) acrylate copolymers, acrylamide-acrylate-methacrylate terpolymers, polyacrylates, poly (meth) acrylates, acrylate-butadiene copolymers, polyvinyl acetate and/or acrylonitrile-butadiene copolymers. They may be used alone or in any mixture.

In the colored layer, a binder is preferably contained in an amount of 2 to 40% by weight, particularly preferably 10 to 30% by weight, relative to the total solid content of the colored layer.

In other embodiments, the binder is preferably contained in the colored layer in an amount of 2 to 60 wt%, particularly preferably 10 to 55 wt%, relative to the total solids content of the colored layer.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the at least one deinking-capable dye is crosslinked with a binder.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the at least one deinking-capable dye is combined with a binder.

It is particularly preferred here that the carbon black is crosslinked or bonded to the binder.

The coloured layer preferably has a content of 1 to 10g/m ² In particular 3 to 8g/m ² Is a weight per unit area of (a).

The colored layer preferably has a thickness of 1 to 10 μm, preferably 2 to 8 μm.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the thermosensitive recording material is suitable for contact with food according to ISEGA development stock, inc.

In order to be suitable for contact with food according to the standards of ISEGA development, inc. Of Aschaffenburg, it is preferable that at least one, in particular all, of the following regulations should be fulfilled:

"method for investigating paper, cardboard and paperboard for food packaging", 2008 edition, corresponds to the regulation of 80.56 in the official summary of the investigation method according to LFGB clause 64 of the food and feed regulations.

2. Migration of certain elements, migration of certain elements according to DIN EN 71 part 3, "complete safety", 8 th edition 2019.

3. Heavy metal content, according to the European Commission and Condition regulations 94/62/EG on 12, 20, 1994, 12, 31, 1994, european Community L365/10 official gazette on 5, 30, 2018, 14, european Union L150/141 official gazette on 6, 2018, 30, finally modified by the regulations (EU) 2018/852 of the European Commission and Condition on 2018.

The regulations of the toxic substances of the model, which are made by the CONEG resource conservation committee of 12 and 14 days 4.1989, are modified in 12 th 2008.

5. Regarding restrictions on the use of certain dangerous substances in electric and electronic equipment, the regulations 2011/65/EU of the european meeting and council at 6, 8, 2011, the official gazette of the european union L174/88 at 7, 1, 2011, and finally the official gazette of the european union L33/32 at 5, 2, 2019, are modified by the regulations (EU) 2019/178 of the committee at 11, 16, 2018.

6. The official gazette of the 1935/2004 guide (EG) of the european meeting and council at 10, 27, 2004, and the european union, L338/4, 11, 13, 2004, was modified by the annex 5.17 of the 596/2009 regulations at 6, 18, 2009, and the official gazette of the european union, L188, 7, 18, 2009, with regard to materials and objects determined for contact with food, which were cancelled by regulations 80/590/EWG and 89/109/EWG.

The published version of food, necessities and feed regulations (food and feed regulations-LFGB) (bgbl.i s.1426) at month 6 and 3 of 7.2013 was finally followed by guidelines at month 6 and 19 of 2020, clauses 97 (bgbl.i s.1328) 30 and 31.

Bfr proposal xxxvi. Paper, cardboard and paperboard for food contact, release of new release by notification No. 62 of federal health publication 14 (1971) 83, and finally modification by notification No. 222 of federal health publication 62 (2019) 1546 of release 1 of month 6 of 2019.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the thermosensitive recording material satisfies a prescribed index of environmental protection marks using a blue sky for thermosensitive paper.

In another preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the thermosensitive recording material satisfies a prescribed index of the environmental protection mark of thermosensitive paper using blue sky in terms of recyclability.

The recyclability of the thermal paper of the thermal recording material using blue sky makes the determination of the environmental protection mark performed here as follows.

To produce the heat-sensitive recording material, a color is applied to the base paper as a tape-shaped carrier material to produce a corresponding layer, wherein the heat-sensitive layer is designed such that it becomes transparent by local thermal action, so that the color layer lying thereunder becomes visible. The thermal recording material here does not comprise additional printing ink on the surface (unprinted thermal recording material).

Since dye removal (deinking) is a common material handling process for image paper or image board, the heat sensitive recording material should not substantially affect this process.

The test for confirming recyclability was performed using the fiber separation and flotation conditions of the indee method 11 (deinking test, version 1 of 2018).

The (unprinted) thermosensitive recording material preferably satisfies at least one, in particular two, of the following indices:

a) In an initial mixture consisting of 100% of wood-free, non-painted, dry toner double-sided printed copy paper with 5% coverage per side (cen_test Master from EN 12281), the brightness reference after flotation was degraded by at most 6 minutes and the filtrate was darkened by at most 3 minutes with 1% of heat-sensitive recording material added compared to the initial mixture without flotation of heat-sensitive recording material.

b) In the initial broke mixture formed from newspapers/magazines (offset, uncoated) in a ratio of 60%/40%, the brightness reference value after flotation deteriorated by at most 6 minutes and the filtrate became deeper by at most 3 minutes with the addition of 5% of the thermosensitive recording material compared to the initial mixture without floatation of the thermosensitive recording material.

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the thermosensitive recording material contains no azo dye, preferably no azo dye, and particularly preferably no azo dye which may fracture one of the following aromatic amines, except for unavoidable amounts (according to guidelines (EG) 1907/2007, appendix XVII, no. 43).

In a preferred embodiment, the thermosensitive recording material of the present invention is further characterized in that the thermosensitive recording material contains, except for unavoidable amounts, the following compounds:

4-aminobiphenyl (92-67-1),

benzidine (92-87-5),

4-chloro-o-toluidine (95-69-2),

2-naphthylamine (91-59-8),

o-aminoazotoluene (97-56-3),

2-amino-4-nitrotoluene (99-55-8),

p-chloroaniline (106-47-8),

2, 4-Diaminoanisole (615-05-4),

4,4' -diaminodiphenyl methane (101-77-9),

3,3' -dichlorobenzidine (91-94-1),

3,3' -dimethoxy benzidine (119-90-4),

3,3' -dimethylbenzidine (119-93-7),

3,3 '-dimethyl-4, 4' -diaminodiphenyl methane (838-88-0),

para-cresol (120-71-8),

4,4' -methylene-bis (2-chloroaniline) (101-14-4),

4,4' -oxydiphenylamine (101-80-4),

4,4' -thiodiphenylamine (139-65-1),

o-toluidine (95-53-4),

2, 4-diaminotoluene (95-80-7),

2,4, 5-trimethylaniline (137-17-7),

4-aminoazobenzene (60-09-3),

o-anisole (90-04-0),

2, 4-Ditoluidine (95-68-1) and/or

2, 6-Ditoluidine (87-62-7).

According to the invention, the heat-sensitive layer on the coloring layer is designed such that it is at least partially obscured and becomes transparent by local thermal action, so that the underlying coloring layer becomes visible.

This is preferably achieved by introducing scattering particles into the thermosensitive layer.

In a preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer comprises at least one scattering particle, in particular polymer particles having a glass transition temperature of-55 to 130 ℃, preferably 40 to 80 ℃.

In a further preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer comprises at least one scattering particle, in particular a polymer microparticle having a core/shell structure, wherein the scattering particle, in particular the polymer microparticle, is selected from the group consisting of: (i) Scattering particles, in particular polymer particles, having an outer shell with a glass transition temperature of 40 ℃ to 80 ℃, and (ii) scattering particles, in particular polymer particles, having an inner shell with a glass transition temperature of 40 ℃ to 130 ℃ and an outer shell with a glass transition temperature of-55 ℃ to 50 ℃, wherein the glass transition temperature of the outer shell is preferably lower than the glass transition temperature of the inner shell.

In another preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer comprises at least one scattering particle, in particular polymer particles having a melting temperature of less than 250 ℃, preferably from 0 ℃ to 250 ℃.

In another preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer includes at least one scattering particle, especially polymer microparticles having an average particle diameter in the range of 0.1 to 2.5 μm, preferably 0.2 to 0.8 μm.

In another preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer includes at least one scattering particle, especially polymer particles having a glass transition temperature of-55 to 130 ℃, preferably 40 to 80 ℃, and an average particle diameter in the range of 0.1 to 2.5 μm, preferably 0.2 to 0.8 μm.

In a further preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer comprises at least one scattering particle, in particular a polymer microparticle having a core/shell structure, wherein the scattering particle, in particular the polymer microparticle, is selected from the group consisting of: (i) Scattering particles, in particular polymer particles, having an outer shell with a glass transition temperature of 40 ℃ to 80 ℃, and (ii) scattering particles, in particular polymer particles, having an inner shell with a glass transition temperature of 40 ℃ to 130 ℃ and an outer shell with a glass transition temperature of-55 ℃ to 50 ℃, wherein the glass transition temperature of the outer shell is preferably lower than the glass transition temperature of the inner shell, and the polymer particles have an average particle diameter in the range of 0.1 to 2.5 μm, preferably 0.2 to 0.8 μm.

In another preferred embodiment, the thermosensitive recording material is characterized in that the thermosensitive layer comprises at least one scattering particle, in particular polymer particles having a melting temperature of less than 250 ℃, preferably 0 ℃ to 250 ℃ and an average particle diameter in the range of 0.1 to 2.5 μm, preferably 0.2 to 0.8 μm.

Glass transition temperatures or melting temperatures of less than 250℃are known to be advantageous. Direct thermal printing cannot be performed at temperatures above 250 c because the temperature time window is outside the printer specifications.

An average particle diameter in the range of 0.1 to 2.5 μm is advantageous, since particles of this size scatter visible light and thus cover the coloured layer as substantially as possible.

The average particle size can be determined by means of a Beckman Coulter apparatus (laser scattering, fraunhofer method).

The scattering particles, in particular the polymer particles, are preferably crystalline, semi-crystalline and/or amorphous.

The above glass transition temperature relates to semi-crystalline or amorphous scattering particles, in particular polymer particles. The melting temperature relates to crystalline scattering particles, in particular polymer particles, or to crystalline parts of scattering particles, in particular polymer particles.

The main characteristic of scattering particles, preferably polymer particles, is light scattering in the visible range. The secondary property is thermal sensitivity.

The polymer particles preferably comprise thermoplastic polymers.

The polymer particles preferably comprise a polymer formed from the polymerization of one or more monomers selected from the group consisting of: acrylonitrile, styrene, butadiene, benzyl methacrylate, phenyl methacrylate, ethyl methacrylate, divinylbenzene, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, alpha-methylstyrene, beta-methylstyrene, acrylamide, methacrylamide, methacrylonitrile, hydroxypropyl methacrylate, methoxystyrene, N-acryloylglycinamide and/or N-methacryloylglycinamide and/or derivatives thereof.

In another embodiment, the polymer microparticles may be polymerized using a plurality of ethylenically unsaturated monomers. Examples of the nonionic monoethylenically unsaturated monomer include styrene, vinyl toluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, and various (C) monomers of (meth) acrylic acid ₁ -C ₂₀ ) Alkyl esters or (C) ₃ -C ₂₀ ) Alkenyl esters, including Methyl Acrylate (MA), methyl Methacrylate (MMA), ethyl (meth) acrylate, methylButyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, lauryl (meth) acrylate, oleic (meth) acrylate, palmityl (meth) acrylate and stearyl (meth) acrylate. Typically, acrylates such as MMA, EA, BA and styrene are preferred monomers for polymerizing and forming the shell of the polymer particles. Difunctional vinyl monomers such as divinylbenzene, allyl methacrylate, ethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and the like can likewise be copolymerized to form crosslinked shells, as described in U.S. patent application 2003-0176535A 1.

In another embodiment, the polymeric microparticles preferably comprise (meth) acrylonitrile copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene acrylate, styrene- (meth) acrylate copolymer, polyacrylonitrile, polyacrylate, or also mixtures of at least two thereof.

The strength and durability of the polymer particles may be affected by cross-linking of the polymer chains.

The scattering particles, in particular polymer particles, may be present in the form of closed polymer particles, open polymer particles and/or solid particles, which may be shaped regularly or irregularly, respectively.

As examples of closed hollow body particles, mention may be made of hollow spherical polymer particles or polymer particles having a core/shell structure.

As examples of the hollow spherical polymer particles or the polymer particles having a core/shell structure, there may be mentioned Ropaque HP-1055, ropaque OP-96 and Ropaque TH-1000.

Mention may be made, in particular, of so-called "cup-shaped" polymer particles as examples of polymer particles. They have the same material in terms of shell, such as closed polymer particles, in particular closed hollow sphere-shaped polymer particles. In contrast to classical hollow body pigments, in which the inner core is formed from a gas (usually from air) completely surrounded by a shell formed from an organic, usually thermoplastic component, the "cup-shaped" polymer particles do not have a closed shell and only surround the inner core in the shape of a bowl or cup that is as much closed as possible.

As further ions of the open polymer particles, mention may be made of mesh cage-shaped polymer particles, as described in WO 2021/062230 A1.

Mention may be made, as examples of solid particles, of polyethylene, polystyrene and cellulose esters.

The scattering particles, in particular the polymer particles, described above may be shaped as regular or irregular.

In an alternative embodiment, the polymer particles are spherical solid particles, preferably irregularly shaped, and/or spherical hollow particles, both preferably in the form of droplets. This preferably includes: polystyrene, such as plastic pigment 756A of trinso LLC and plastic pigment 772HS of trinso LLC; polyethylene, such as Chemipear 10W401 by Mitsui Chemical inc; spherical hollow body fine particles (HSP)/spherical hollow body pigments, such as Ropaque TH-500EF of The Dow Chemical Co; modified polystyrene particles, such as Joncryl 633 of BASF Corp; 1, 2-Diphenoxyethane (DPE); ethylene glycol meta-toluene ether (EGTE) and/or diphenyl sulfone (DPS). They may be used alone or in any mixture. These polymer particles preferably have an average particle diameter of 0.2 μm, 0.3 μm, 0.4 μm, 0.45 μm, 0.75 μm or 1.0 μm.

The scattering particles, in particular polymer particles, are preferably contained in the thermosensitive layer in an amount of 20 to 60 wt%, preferably 30 to 50 wt%, relative to the solid content of the thermosensitive layer.

The heat-sensitive layer preferably comprises at least one heat-sensitive material having a melting temperature in the range of 40 to 200 ℃, preferably 80 to 140 ℃ and/or a glass transition temperature in the range of 40 to 200 ℃, preferably 80 to 140 ℃.

The thermosensitive layer preferably includes at least one thermosensitive material having an average particle diameter in the range of 0.2 to 4.0 μm, preferably 0.5 to 2.0 μm.

In a further embodiment, the heat-sensitive layer is preferably characterized in that it comprises or consists of scattering particles, in particular a heat-sensitive material as scattering particles, in particular a heat-sensitive material selected from the group consisting of: biopolymers, modified biopolymers, fats, natural waxes, partially synthetic waxes and/or synthetic waxes, with partially synthetic waxes being preferred.

Such thermosensitive recording materials are unique in particular in that sustainable raw materials are employed.

Suitable examples of biopolymers include natural biopolymers such as proteins, peptides, nucleic acids, alpha-polysaccharides, beta-polysaccharides, lipids, polyhydroxyalkanoates, keratans, softwoods and/or lignin.

It is also possible to use so-called process biopolymers such as virgin polymers, biobased and degradable petroleum-based polymers.

Examples of virgin polymers can be mentioned recycled fibers (such as viscose and cellophane) and celluloid as well as thermoplastic starch.

Examples of biobased polymers may be mentioned polylactic acid esters, polyhydroxybutyrate esters, lignin-based thermoplastics and/or epoxy acrylates based on oils, in particular linseed and palm oils.

Examples of degradable petroleum-based polymers that may be mentioned are polyesters, polyvinyl alcohol, polybutylene adipate-terephthalate, polybutylene succinate, polycaprolactone and/or polyglycolide. They may be used alone as a blend.

Suitable examples of modified biopolymers include, for example, esters of cellulose and/or lignin. They may be used alone or as a blend.

Suitable examples of fats include, for example, fats based on saturated and/or unsaturated fatty acids, such as butyric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, myrcenic acid, myristoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, gadoleic acid and/or arachidonic acid.

Suitable examples of natural waxes include, for example, carnauba wax, candelilla wax, and/or montan wax.

Suitable examples of synthetic waxes include, for example, carbon (hydrocarbon) waxes, polyolefin waxes, HD-PE waxes, EVA waxes, polyester waxes, polyethylene glycol waxes, PTFE waxes, fluorowaxes, fischer-tropsch waxes, synthetic fatty acid esters, and/or reconstituted waxes. They may be used alone or as a blend.

Suitable examples of partially synthetic waxes include, for example, stearic acid amide waxes and/or palmitic acid amide waxes. They may be used alone or as a blend.

Waxes from the group of animal waxes, vegetable waxes, mineral waxes and/or micro waxes are also conceivable.

It is preferred to use partially synthetic waxes because of their advantageous cost performance.

Biopolymers, modified biopolymers, fats, natural waxes, partially synthetic waxes and synthetic waxes may be used alone or as blends.

In this embodiment, the scattering particles, preferably the heat sensitive material, are selected from amide waxes, stearic acid amide waxes, palmitic acid amide waxes or combinations thereof.

In this embodiment, the scattering particles, in particular the thermally sensitive material, are present in the thermally sensitive layer in an amount of 5 to 100 wt.%, preferably 40 to 100 wt.% and particularly preferably 40 to 95 wt.%, relative to the total weight of the thermally sensitive layer.

In this embodiment, the thermosensitive recording material is preferably characterized in that the scattering particles, preferably the thermosensitive material, have a melting temperature in the range of 30 to 250 ℃, especially in the range of 40 to 200 ℃.

In another preferred embodiment, the thermosensitive recording material of the present invention is characterized in that the thermosensitive layer includes 20 to 60 wt.%, preferably 30 to 50 wt.% of scattering particles, especially polymer particles having an average particle diameter in the range of 0.1 to 2.5 μm, preferably 0.2 to 0.8 μm, 10 to 80 wt.%, preferably 25 to 60 wt.% of thermosensitive material having a melting temperature in the range of 40 to 200 ℃ and/or a glass transition temperature in the range of 40 to 200 ℃, and 1 to 30 wt.%, preferably 5 to 20 wt.% of binder.

Such thermosensitive recording materials are unique, inter alia, in their functionality, their environmental protection properties (sustainability) and/or their economical preparation (simple and inexpensive), and in particular in advantageous combinations of these three properties.

The heat-sensitive material additionally preferably contributes to the opacity (hiding power) of the heat-sensitive layer, for example by absorbing and/or scattering light. It is expected that the thermal material will rapidly melt locally by local heat action through the thermal print head of the direct thermal printer and thus produce local "softening" of the polymer particles and thus local reduction of the covering force (anti-reflection) so that the covering layer becomes transparent and the underlying coloured layer becomes visible.

The thermosensitive layer may also be referred to as a sensitizer or a thermal solvent.

The heat-sensitive material preferably comprises: one or more fatty acids based on vegetable and/or animal oils, such as stearic acid, behenic acid or palmitic acid, one or more fatty acid amides, such as stearamide, behenamide or palmitamide, ethylene bis-fatty acid amides, such as N, N '-ethylene bis-stearamide or N, N' -ethylene bis-oleamide, one or more fatty acid alkanolamides, in particular methylolated fatty acid amides, such as N- (hydroxymethyl) stearamide, N-methylol palmitamide, hydroxyethyl stearamide, one or more waxes, such as polyethylene wax, candelilla wax, carnauba wax or montan wax, one or more carboxylic acid esters, such as dimethyl terephthalate, dibenzyl terephthalate, benzyl-4-benzyloxy benzoate, di- (4-methylbenzyl) oxalate, di- (4-chlorobenzyl) oxalate or di- (4-benzyl) oxalate, ketones, such as 4-acetylbiphenyl, one or more aromatic ethers, such as 1, 2-diphenoxyethane, 1, 2-di- (3-methylphenoxy) ethane, 2-benzyloxynaphthalene, 1, 2-bis- (phenoxymethyl) benzene or 1, 4-diethoxynaphthalene, one or more aromatic sulfones, such as diphenyl sulfone, and/or aromatic sulfonamides, such as 2-,3-, 4-toluenesulfonamide, benzenesulfonanilide or N-benzyl-4-toluenesulfonamide, or one or more aromatic hydrocarbons, such as 4-benzylbiphenyl, or a combination of the foregoing. They may be used alone or in any mixture.

Stearamide is preferred because of its favorable cost performance.

The heat-sensitive material is preferably present in the heat-sensitive layer in an amount of about 10 to about 80% by weight, particularly preferably in an amount of about 25 to about 60% by weight, relative to the total solids content of the heat-sensitive layer.

Optionally, a slip agent or release agent may also be present in the thermosensitive layer. Such slip or release agents are present especially when no protective or other layer is present on the heat sensitive layer.

These agents are preferably fatty acid metal salts, such as zinc stearate or calcium stearate, or also behenates, synthetic waxes, for example in the form of fatty acid amides, such as stearic acid amide and behenamide, fatty acid alkanolamides, such as stearic acid methylol amide, paraffin waxes of different melting points, ester waxes of different molecular weights, acrylic waxes of different hardness, ethylene waxes, and/or natural waxes, such as carnauba wax or montan wax. They may be used alone or in any mixture.

Zinc stearate is preferred because of its advantageous cost performance.

The slip agent or release agent is preferably present in the heat-sensitive layer in an amount of about 1 to about 10% by weight, particularly preferably about 3 to about 6% by weight, relative to the total solids content of the heat-sensitive layer.

In another preferred embodiment, at least one binder (adhesive) is present in the thermosensitive layer. The binder is preferably a water-soluble starch, starch derivative, starch-based biological latex of the EcoSphere type, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gelatin, casein, partially or fully saponified polyvinyl alcohol, chemically modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, sodium polyacrylate, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, styrene-butadiene copolymer, acrylamide- (meth) acrylate copolymer, acrylamide-acrylate-methacrylate terpolymer, polyacrylate, poly (meth) acrylate, acrylate-butadiene copolymer, polyvinyl acetate and/or acrylonitrile-butadiene copolymer. They may be used alone or in any mixture.

Partially or semi-saponified polyvinyl alcohols are preferred because of their advantageous cost performance.

The binder is preferably present in the thermosensitive layer in an amount of 1 to 30 wt%, preferably 5 to 20 wt%, relative to the total solid content of the thermosensitive layer.

In order to achieve the targeted performance characteristics of the thermal recording material in terms of application technology, the binder is preferably present in the thermal layer in crosslinked form, the optimum degree of crosslinking of the binder being set in the presence of a crosslinking agent (crosslinker) in the drying step during the coating process.

The cross-linking agent may be: polyaldehydes, such as glyoxal, dialdehyde starch, glutaraldehyde, in some cases blended with boron salts (borax); salts or esters of glyoxylic acid; a cross-linking agent based on zirconium ammonium carbonate; polyamidoamine-epichlorohydrin resins (PAE resins); adipic acid dihydrazide (AHD); boric acid or a salt thereof; a polyamine; an epoxide resin; formaldehyde oligomers; cyclic urea; methylol urea; melamine formaldehyde oligomers, and the like. They may be used alone or in any mixture.

Zirconium ammonium carbonate and polyamidoamine-epichlorohydrin resins (PAE resins) are particularly preferred for reasons of compliance with food regulations.

Self-crosslinking adhesives, such as specifically modified polyvinyl alcohols or acrylates, can be crosslinked completely without crosslinking agents due to the reactive crosslinkable groups already formed in the adhesive polymer.

The crosslinking agent is preferably present in an amount of about 0.01 to about 25.0% by weight, particularly preferably in an amount of about 0.05 to about 15.0% by weight, relative to the total solids content of the coloured layer.

In another preferred embodiment, the heat sensitive layer comprises a pigment. These pigments are preferably different from the pigments of the colored layer. The use of these pigments has the following advantages in particular: these pigments can fix on their surface the melt of chemicals that occur during thermal printing. The surface whiteness and opacity of the thermosensitive layer can also be controlled by pigments and printability with conventional print colors.

Particularly suitable pigments are inorganic pigments, whether of synthetic or natural origin, preferably clays, precipitated or natural calcium carbonate, aluminum oxide, aluminum hydroxide, silicon dioxide, precipitated and pyrogenic silicon dioxide (e.g. air-dispersed), diatomaceous earth, magnesium carbonate, talc, kaolin, titanium oxide, bentonite, but also organic pigments, such as hollow pigments with styrene/acrylate copolymer walls or urea/formaldehyde condensation polymers. They may be used alone or in any mixture.

Calcium carbonate, aluminum hydroxide, fumed silica are preferred because they can realize particularly advantageous application technical properties of the thermosensitive recording material in terms of printability of its later-on commercial print color.

The pigment is preferably present in the thermosensitive layer in an amount of about 2 to about 50% by weight, particularly preferably in an amount of about 5 to about 20% by weight, relative to the total solids content of the thermosensitive layer.

The thermosensitive layer may also have a carbon black component and/or a dye/color pigment.

In order to control the surface whiteness of the thermosensitive recording material of the present invention, an optical brightening agent may be processed into the thermosensitive color-developing layer. This is preferably stilbene.

The thermosensitive layer may also contain an inorganic oil absorbing white pigment.

Examples of such inorganic oil absorbing white pigments include natural or calcined kaolin, silica, bentonite, calcium carbonate, aluminum hydroxide, especially boehmite, and mixtures thereof.

The inorganic oil-absorbing white pigment is preferably present in the thermosensitive layer in an amount of about 2 to about 50% by weight, particularly preferably about 5 to about 20% by weight, relative to the total solids content of the thermosensitive layer.

In order to improve certain coating technical properties, it is in particular preferable to add further components, in particular rheology auxiliaries, such as thickeners and/or surfactants, to the components of the thermosensitive recording materials of the present invention.

The further components are each preferably present in conventional amounts known to the person skilled in the art.

The thermosensitive layer preferably has a concentration of 1 to 8g/m ² In particular 2 to 6g/m ² Is a weight per unit area of (a).

The thermosensitive layer preferably has a thickness of 1 to 10 μm, preferably 2 to 8 μm.

In a further preferred embodiment, the thermosensitive recording material is preferably characterized in that an insulating layer is present between the tape-shaped carrier material and the coloring layer.

In an alternative embodiment, the thermosensitive recording material is preferably characterized in that the coloring layer is both a coloring layer and an insulating layer.

At the same time, a reduction in the thermal conductivity through the thermal recording material is achieved for such barrier layers or colored layers of the colored layer and the barrier layer. Local thermal effects can thereby be achieved with direct thermal printers more efficiently and at higher thermal printing speeds. The cover layer becomes transparent more quickly by the heat introduced and thus the sensitivity is improved.

Thus less dye is required, which promotes improved recyclability (more ductile, separation of dye from carrier material components) in the recycling of materials, especially in the recycling of waste paper.

The barrier layer or the colored layer, which is both a colored layer and a barrier layer, preferably has a brookfield smoothness of more than 50s, particularly preferably more than 100s and very particularly preferably from 100 to 250 s.

The insulation layer or the colored layer, which is both a colored layer and an insulation layer, preferably comprises an insulating material.

The thermosensitive recording material having the insulating layer or the coloring layer which is also an insulating layer preferably has lower thermal conductivity than the thermosensitive recording material having no insulating layer or the coloring layer which is not also an insulating layer.

The insulating material preferably comprises kaolin, particularly preferably calcined kaolin, and mixtures thereof.

The insulation material may also comprise hollow sphere pigments, in particular hollow sphere pigments comprising styrene-acrylate copolymers.

These hollow sphere pigments preferably have a glass transition temperature of 40 to 80 ℃ and/or an average particle size of 0.1 to 2.5 μm.

The insulating material is preferably present in the insulating layer in an amount of about 20 to about 80 wt.%, particularly preferably in an amount of about 30 to about 60 wt.%, relative to the total solids content of the insulating layer.

In the colored layer which is both a colored layer and an insulating layer, the heat insulating material is preferably present in an amount of about 30 to about 70% by weight, particularly preferably in an amount of about 30 to about 60% by weight, relative to the total solid content of the colored layer which is both a colored layer and an insulating layer.

In order to achieve the targeted performance characteristics of the thermal recording material in terms of application technology, the binder is preferably present in crosslinked form in the barrier layer and/or the color layer, wherein the optimum degree of crosslinking of the binder is adjusted in the presence of a crosslinking agent (crosslinker) in the drying step during the coating process.

The crosslinking agent is preferably present in an amount of about 0.01 to about 25.0, particularly preferably about 0.05 to about 15.0, relative to the total solids content of the barrier layer or the colored layer.

The insulation layer preferably has a weight of 1 to 5g/m ² In particular 2 to 4g/m ² Is a weight per unit area of (a).

In another embodiment, the insulation layer preferably has a weight of 1 to 10g/m ² In particular 2 to 6g/m ² Is a weight per unit area of (a).

The insulating layer preferably has a thickness of 1 to 10 μm, preferably 2 to 8 μm.

The pigmented layer, which is both a pigmented layer and an insulating layer, preferably has a content of 1 to 10g/m ² In particular 3 to 8g/m ² Is a weight per unit area of (a).

The colored layer, which is both a colored layer and an insulating layer, preferably has a thickness of 1 to 12 μm, preferably 4 to 8 μm.

In a further preferred embodiment, the thermosensitive recording material is preferably characterized in that a layer comprising starch (starch coating line) and/or modifications thereof (modified starch) is present directly on at least one side of the band-shaped carrier material, preferably directly on both sides of the band-shaped carrier material.

Preferably at a rate of 0.1 to 3, particularly preferably 0.2 to 1.5g/m ² Is applied to the starch coating line.

The starch coating on the side of the band-shaped carrier material where the coloring layer is present has the following advantages: the tape-shaped carrier material is encapsulated and thus improves the adhesion of the coloring layer and can reduce or prevent the penetration of the coloring layer into the tape-shaped carrier material.

The starch coating on the side of the tape-shaped carrier material where the coloring layer is not present has the following advantages: penetration of the colored layer by the tape-shaped carrier material may be reduced or prevented.

The layer comprising starch preferably has a brookfield smoothness of more than 20s, particularly preferably more than 50s and very particularly preferably from 50 to 200 s.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that a protective layer is present on the thermosensitive layer.

The protective layer preferably has a brookfield smoothness of more than 200s, preferably more than 400s and very particularly preferably from 400 to 1500 s. Most preferred is a brookfield smoothness of 400 to 1300 s.

This protective layer is located on the side of the thermosensitive layer where the colored layer is absent.

This protective layer preferably comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

Suitable binders include water-soluble starches, starch derivatives, starch-based biological latices of the EcoSphere type, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, partially or fully saponified polyvinyl alcohols, chemically modified polyvinyl alcohols, such as acetoacetyl, diacetone, carboxyl modified polyvinyl alcohols, silanol modified polyvinyl alcohols, or styrene-maleic anhydride copolymers, styrene-butadiene copolymers, acrylamide- (meth) acrylate copolymers, acrylamide-acrylate-methacrylate terpolymers, polyacrylates, poly (meth) acrylates, acrylate-butadiene copolymers, polyvinyl acetate and/or acrylonitrile-butadiene copolymers. They may be used alone or in any mixture.

Suitable inorganic pigments include inorganic pigments, whether of synthetic or natural origin, preferably clay, precipitated or natural calcium carbonate, alumina, aluminum hydroxide, silica, precipitated and fumed silica (e.g. air-dispersed), diatomaceous earth, magnesium carbonate, talc, kaolin, titanium oxide, bentonite, but also organic pigments, such as hollow pigments with styrene/acrylate copolymer walls or urea/formaldehyde condensation polymers. They may be used alone or in any mixture.

Suitable organic pigments include hollow pigments having styrene/acrylate copolymer walls or urea/formaldehyde condensation polymers. They may be used alone or in any mixture.

The binder is preferably present in the protective layer in an amount of about 40 to about 90% by weight, particularly preferably in an amount of about 50 to about 80% by weight, relative to the total solids content of the protective layer.

The pigment is preferably present in the protective layer in an amount of from about 5 to about 40% by weight, particularly preferably from about 10 to about 30% by weight, relative to the total solids content of the protective layer.

In order to achieve the targeted performance characteristics of the thermal recording material in terms of application technology, the binder is preferably present in the protective layer in crosslinked form, wherein the optimum degree of crosslinking of the binder is adjusted in the presence of a crosslinking agent (crosslinker) in the drying step during the coating process.

The crosslinking agent is preferably present in an amount of about 0.01 to about 25.0% by weight, particularly preferably in an amount of about 0.05 to about 15.0% by weight, relative to the total solids content of the protective layer.

The protective layer preferably further comprises at least one slip agent or at least one release agent.

These agents are preferably fatty acid metal salts, such as zinc stearate or calcium stearate, or also behenates, synthetic waxes, for example in the form of fatty acid amides, such as stearic acid amide and behenamide, fatty acid alkanolamides, such as stearic acid methylol amide, paraffin waxes of different melting points, ester waxes of different molecular weights, acrylic waxes of different hardness, ethylene waxes, and/or natural waxes, such as carnauba wax or montan wax.

The slip or release agent is preferably present in an amount of about 1 to about 30% by weight, particularly preferably in an amount of about 2 to about 20% by weight, relative to the total solids content of the protective layer.

In order to control the surface whiteness of the thermosensitive recording material of the present invention, an optical brightening agent, particularly stilbene, may be processed into the protective layer.

The protective layer preferably has a content of 0.3 to 5.0g/m ² In particular 1.0 to 3.0g/m ² Is a weight per unit area of (a).

The protective layer preferably has a thickness of 0.3 to 6.0 μm, preferably 0.5 to 2.0 μm.

The use of a protective layer has the advantage that the recording material is better protected from external influences.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that an adhesive layer is present on the tape-shaped carrier material on the side without the coloring layer.

If a starch coating line is present, the starch coating line is located between the tape-shaped carrier material and the adhesive layer.

The adhesive layer preferably comprises at least one adhesive, preferably a heat activatable adhesive, in particular an attachment adhesive.

The adhesive, preferably the heat-activatable adhesive and in particular the attachment adhesive, is particularly preferably a rubber-and/or acrylate-based adhesive.

The adhesive layer preferably has a weight of 1 to 40g/m ² In particular 12 to 25g/m ² Is a weight per unit area of (a).

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that a siliconized separation layer is present on the thermosensitive layer.

The terms "siliconized separation layer" and "siliconized layer" are to be understood as synonymous in the sense of "covering with a layer of silicone". These layers preferably consist of silicone or comprise at least 90% by weight, preferably at least 95% by weight and particularly preferably at least 99% by weight and very particularly preferably comprise silicone alone, apart from unavoidable trace substances or auxiliaries, for example for UV curing of the silicones.

The siliconized separating layer preferably has a brookfield smoothness of more than 400s, particularly preferably more than 800s and very particularly preferably from 800 to 2000 s.

If a protective layer, in particular as defined above, is present on the heat-sensitive layer, the siliconized separating layer is preferably located on this protective layer.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that a diffusion layer is formed between the siliconized separation layer and the layer located thereunder, preferably the thermosensitive layer. This diffusion layer is preferably formed by diffusing at least a part of the siliconized separating layer into a plane in the upper region of the underlying layer, wherein preferably 5 to 50 wt.%, particularly preferably 6 to 45 wt.% and in particular 7 to 40 wt.% of the siliconized separating layer diffuses into the upper region of the underlying layer. Such diffusion layers are described, for example, in EP 3 221 153 A1.

When an adhesive layer as described above is also present, the siliconized separation layer is present.

The presence of a siliconized separating layer on the tape-shaped carrier material on the heat-sensitive layer and the adhesive layer on the side without the colored layer has the following advantages: the thermosensitive recording material may be used as a thermosensitive recording material without a carrier ("no liner").

No carrier means that the (self-adhesive) thermosensitive recording material of the present invention is not applied on a carrier material, but wound on itself. The advantage of this is that the manufacturing costs can be further reduced, more extended meters per roll can be achieved, handling costs for handling the liner are not required and more labels can be transported per certain cargo space volume.

When a siliconized separating layer is present, it is then preferred that at least one lamellar pigment is contained in the heat-sensitive layer or in a layer directly below the siliconized separating layer.

The at least one flake pigment is preferably chosen from kaolin, al (OH) ₃ And/or talc. Particular preference is given to using kaolin. Very particular preference is given to using coated kaolin (streichkalins). Such pigments are for example obtainable under the trade name kaolin ASP 109 (BASF, germany).

The use of these flake pigments, in particular kaolin, has mainly the following advantages: the heat sensitive layer or the layer directly below the silicone-based separation layer may be very well siliconized.

Flake-like pigments are understood to be pigments whose diameter to thickness ratio is from about 7 to 40 to 1, preferably from about 15 to 30 to 1.

The particle size of the flake-like pigment is preferably set such that at least about 70%, preferably at least about 85% of the particles have a particle size of about <2 μm (sedimentation diagram particle size analysis). The pH of the flake-form pigment in aqueous solution is preferably from 6 to 8. The at least one flake-form pigment is preferably present in the developed heat-sensitive layer or in a layer directly below the siliconized separating layer in an amount of from about 5 to about 60% by weight, particularly preferably in an amount of from about 15 to about 55% by weight, relative to the total solids content of the respective layer.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that the siliconized separating layer comprises a siloxane, preferably a poly (organo) siloxane, especially an acryl-poly (organo) siloxane.

In another embodiment, the siliconized separation layer comprises a mixture of at least two siloxanes. Preferred are mixtures of at least two acryl-poly (organo) siloxanes.

Examples of very particularly preferred siloxanes are those under the trade nameRC902 and->Siloxanes obtainable under RC711 (Evonik, germany).

In another embodiment, the thermal recording material is preferably characterized in that the siliconized separation layer comprises at least one silicone acrylate, preferably formed by condensation of at least one silicone acrylate.

The silicone-based separation layer is preferably anhydrous. It is also preferred that the siliconized separation layer does not contain a Pt catalyst.

The siliconized separating layer preferably comprises an initiator, particularly preferably a photoinitiator. The initiator is used to cure the silicone radicals.

Very particular preference is given here toPhotoinitiator A18 (Evonik, germany).

The siliconized separating layer may preferably contain further additives, such as matting agents and/or adhesion additives.

The siliconized separating layer preferably has a content of 0.1 to 5g/m ² Or 0.3 to 5.0g/m ² In particular 1.0 to 3.0g/m ² Or preferably 0.2 to 2.0g/m ² Is a weight per unit area of (a).

The siliconized separation layer preferably has a thickness of 0.3 to 6.0 μm, preferably 0.5 to 2.0 μm.

Due to its hydrophobic nature, the application of a siliconized separation layer generally results in a heat-sensitive recording material resistant to hydrophilic agents such as alcohols or water. The silicone-based release layer is therefore also suitable as a protective layer.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that the thermosensitive recording material has a residual humidity of 2 to 14%, preferably 2 to 12% and very particularly preferably 3 to 10%. Most preferred is a residual humidity of 3 to 8%.

The residual humidity can be measured as described in connection with the examples.

It is assumed that the opacity in the thermosensitive layer is not only created by the scattering particles, in particular the polymer particles themselves, but also by the air encapsulated between the scattering particles, in particular the polymer particles (open pores). As moisture penetrates into these "holes", air is expelled and opacity is reduced. This may result in a gray material that is not preferred.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that the thermosensitive recording material has a surface whiteness of 35 to 60%, preferably 45 to 50%.

Residual humidity in the ranges given has the following advantages: there is a higher relative print contrast after printing and advantageous application technical properties, such as better readability.

Surface whiteness (paper white) can be measured according to ISO 2470-2 (2008) using an Elrepho 3000 spectrophotometer.

In another preferred embodiment, the thermosensitive recording material is preferably characterized in that the contrast ratio between the position where the thermosensitive layer has become transparent by local heat action and the position where the thermosensitive layer has not become transparent by local heat action is 40 to 80%, particularly 50 to 70%.

This contrast can be calculated by differencing the optical densities of the background and the typeface. The measurement of the optical density (o.d.) is carried out, for example, by means of a densitometer.

All of the above layers may be formed as single or multiple sublayers.

The support material preferably has a brookfield smoothness of more than 20s, particularly preferably more than 30s and very particularly preferably more than 50s on the side to which the coloured layer is applied.

The coloring layer preferably has a brookfield smoothness of greater than 50s, particularly preferably greater than 100s and very particularly preferably greater than 150s on the side to which the thermosensitive layer is applied.

The thermosensitive layer preferably has a brookfield smoothness of greater than 100s, particularly preferably greater than 150s, on the side without the colored layer.

The support material preferably has a brookfield smoothness of from 20 to 400s, particularly preferably from 30 to 300s and very particularly preferably from 50 to 200s, on the side to which the coloured layer is applied. Most preferred is a brookfield smoothness of 50 to 150 s.

The coloring layer preferably has a brookfield smoothness of 50 to 400s, particularly preferably 100 to 250s and very particularly preferably 150 to 250s on the side to which the thermosensitive layer is applied.

Such thermosensitive recording materials have the advantage of high dynamic sensitivity.

Advantageously, a smooth strip-like carrier material has been presented and this smoothness is maintained on the individual coating layers. The smoother the substrate is constructed from below, the better the final smoothness and thus the sensitivity of the final product.

Preferably, each layer applied to the tape-like carrier material has a brookfield smoothness at its upper side (i.e. on the side without the tape-like carrier material) at least exactly equal to or greater than the brookfield smoothness of the layer lying respectively thereunder.

Each layer applied to the tape-like carrier material preferably has a brookfield smoothness of at least 5% (percent improvement) on its upper side (i.e. on the side without the tape-like carrier material) relative to the layer respectively located therebelow.

Each layer applied to the tape-like carrier material preferably has a brookfield smoothness of at least 5% (absolute improvement) on its upper side (i.e. on the side without the tape-like carrier material) relative to the layer lying respectively thereunder.

The thermosensitive recording material according to the present invention can be obtained by a known production method.

The present invention also relates to a method for producing the thermosensitive recording material as described above. It is preferred that the thermosensitive recording material according to the present invention is applied by a method in which a (aqueous) suspension of the starting material comprising the respective layers is successively applied onto the tape-shaped carrier material, wherein the (aqueous) applied suspension has a solids content of 8 to 50 wt.%, preferably 10 to 40 wt.%, and is applied in a curtain coating method at a running speed of the brushing apparatus of at least 200 m/min.

Alternatively, it is also possible to apply the (aqueous) suspension of the starting material comprising the individual layers with a tool.

This method is advantageous in particular from an economic point of view and due to the uniform application of the tape-like carrier material.

If the solid content value is less than about 8% by weight, economical efficiency is deteriorated because a large amount of water must be removed in a short time by mild drying, which adversely affects the brushing speed. On the other hand, if the value exceeds 60% by weight, this only results in increased process outlay, in order to ensure stability of the color curtain film applied during the coating process and drying of the film applied, since in this case the machine must again be operated very rapidly.

Free-falling curtain of coating dispersion is formed in the curtain coating process. Due to free fall, the coating dispersion in the form of a film (curtain film) is "cast" onto a substrate to apply the coating dispersion to the substrate. DE 10 196 052 T1 discloses the use of a curtain coating method in the preparation of information recording materials, wherein a multi-layered recording layer is realized by applying a curtain consisting of a plurality of coating dispersion films onto a substrate.

Embodiments of the method according to the invention are also conceivable in which a "double curtain" is used. This means that two layers are applied directly one after the other. The application takes place directly next to one another, so that the layer applied first is not dried before the next layer is applied. The application of the two layers is thus preferably carried out in the manner of "wet in wet".

All definitions concerning curtain coating processes apply similarly to dual curtain coating processes.

The advantage of the "wet in wet" application by means of the double curtain coating method is that the two layers have a stronger connection and in particular the adhesion promoter located between them can be dispensed with.

In a preferred embodiment of the method of the invention, the deaerated aqueous application suspension has a viscosity of about 100 to about 1000mPas (Brookfield, 100 revolutions per minute, 20 ℃). If the value is below about 100mPas or exceeds about 1000mPas, this results in a lack of flowability of the application material at the application device. The viscosity of the degassed aqueous application suspension is particularly preferably from about 200 to about 500mPas. The viscosity of the coating materials in the double curtain film following one another should decrease from bottom to top. In the case of a coating setting error, not only the possibility of forming a heel at the curtain contact point but also the occurrence of "wetting defects" are increased.

In a preferred embodiment, to optimize the method, the surface tension of the aqueous applied suspension is set to about 25 to about 70mN/m, preferably about 35 to about 60mN/m, measured according to the standard for gas blowing pressure tensiometry (ASTM D3825-90), as described below. Better control of the brushing method is obtained when the dynamic surface tension of the brushing color is determined and set pointedly by selecting the appropriate surfactant and by taking the required amount of surfactant.

The dynamic surface tension is measured by means of a blow pressure tension measurement. The maximum internal pressure of the bubble formed in the liquid by the capillary was measured. According to the young-laplace equation, the internal pressure p (laplace pressure) of a spherical bubble depends on the radius of curvature r and the surface tension σ:

if a bubble is generated at the tip of a capillary in the liquid, the curvature increases and then decreases again, whereby a pressure maximum occurs. When the radius of curvature corresponds to the capillary radius, the greatest curvature and thus the greatest pressure occurs.

Pressure curve at the time of blowing pressure measurement, position of pressure maximum:

the radius of the capillary is determined by means of a reference measurement, which is carried out with a liquid, mostly water, having a known surface tension. If the radius is known, it can be determined by the pressure maximum p _max To calculate the surface tension. Since the capillary is immersed in the liquid, the hydrostatic pressure p must be subtracted from the measured pressure ₀ The hydrostatic pressure is derived from the immersion depth and the liquid density (which is done automatically on modern measuring instruments). The following formula is thus obtained for the blow air pressure method:

the measured value corresponds to the surface tension at a certain surface lifetime, i.e. the time from the start of bubble formation until the occurrence of the pressure maximum. By changing the generation speed of the bubbles, the dependence of the surface tension on the lifetime can be detected, thereby obtaining a curve in which the change of the surface tension with time is recorded.

This dependence plays an important role for the use of surfactants, since in many processes, the equilibrium value of interfacial tension is completely unattainable, partly due to the small surfactant diffusion and adsorption rates.

The formation of the individual layers can be carried out in-line or off-line in a separate brushing process.

In particular, in order to ensure that the layers described in detail above have the above-mentioned brookfield smoothness, the following method steps are preferably carried out.

The strip-shaped carrier material is preferably smoothed in the first cylinder. Such a high smoothness of one or both sides, produced by such a treatment process, has provided advantages to the tape-like carrier material. The smoothness and/or the use of the additional enamelling can be further improved by subsequent calendering, preferably before the first brushing device, and/or for achieving good shaping.

If the starch coating line as defined above is applied, the starch coating line is preferably applied by a film press before the application of the coloured layer by means of a knife coater.

Starch on the back side is particularly advantageous in order to prevent the paint color from being penetrated by the blade coater.

It is also possible to apply the coloured layer directly with a film press. However, there are disadvantages in terms of smoothness variation compared to doctor blade coaters. For important dynamic sensitivity of the final product, a blade coater is used to impart good base smoothness to the material. There is a correlation between the final smoothness and the dynamic sensitivity.

It is also conceivable to apply the coloured layer with a film press or even with a curtain coater. The advantages of smoothness, although lost, can be reproduced again with a calender, especially in the case of film presses. But only when hollow spheres are not used, as they may be crushed by the film press.

The barrier layer (if present) is similarly applied.

The siliconized layer, if present, is likewise applied.

The same applies to the protective layer (if present). The protective layer, if present, may also be printed instead. Those protective layers which are curable by means of actinic radiation are particularly suitable in terms of processing and their technical properties. The term "actinic radiation" is understood to mean UV or ionizing radiation, such as an electron beam.

The thermosensitive layer is preferably applied by means of curtain coating, as explained above.

When a strip-shaped carrier material, in particular paper, is applied to one side, the curl thus produced should then be smoothed out.

This is preferably accomplished with an LAS humidifying device (LAS liquid applicator system). For this purpose, a water film is applied to the less painted surface and subsequently dried. Whereby again a so-called flat sub-layer is obtained. The surface slightly deteriorates upon application of the water film.

A preferred variant for protecting the surface is a vapor humidifier. Where steam is blown instead of water. Where the surface is not damaged. This is very well suited for applications where the highest surface quality must be achieved.

Another possibility is a spray humidifier that applies a mist of water.

All of the above layers may be formed as single or multiple sublayers.

The present invention also relates to a thermosensitive recording material obtainable according to the above method.

The invention also relates to the use of a thermosensitive recording material as described above as a receipt paper roll, as an adhesive label (roll) (also in the fields of refrigeration and cryogenic), and as a ticket (roll). They have in particular a functional side and/or a rear side (with colour, black/grey) and can be preprinted. The rolls mentioned are preferably present in typical widths and lengths.

The invention also relates to a method for decolorizing a heat-sensitive recording material comprising a band-shaped carrier material, a coloring layer on one side of the band-shaped carrier material and a heat-sensitive layer on the coloring layer such that the coloring layer is at least partially obscured, wherein the heat-sensitive layer is designed such that the heat-sensitive layer becomes transparent by local thermal action such that the coloring layer located thereunder, in particular as defined above, becomes visible in order to obtain a fibrous material mixture, the method comprising the steps of:

-providing a mixture of said thermosensitive recording material and at least one further paper, in particular at least one broke;

-decolorizing said mixture in a deinking process to obtain a fibrous material mixture.

The thermosensitive recording material decolored by this method includes or is preferably a thermosensitive recording material as described above. Therefore, all definitions and designs of the thermosensitive recording material are similarly applicable to the method for decoloring thermosensitive recording material according to the present invention.

The deinking process is preferably characterized by the following features.

After removing foreign matter such as clips, the paper is preferably mechanically crushed or defibrated and mixed with water. The waste pulp produced here may be subjected to so-called flotation. For this purpose, it is now preferred to add it to the chemical in several processes, for example:

a complexing agent, wherein the complexing agent,

caustic soda is used as a raw material for the caustic soda,

the flocculant is used for the treatment of the sewage,

the surfactant is used as a surfactant in the preparation of the water-soluble polymer,

water glass, and/or

Hydrogen peroxide.

In flotation, other particles (e.g. colour particles or fillers) separated from the fibres, which are present in the material suspension after the comminution and fibre separation steps, are collected on the gas bubbles by the collecting chemicals during flotation and transported by the gas bubbles to the surface of the flotation cell. A dirt-carrying foam is produced, which is called a froth (Flotat) and may contain fibres and fillers in addition to dissolved coloured particles. This foam is skimmed off, purified and can be used as ash in papermaking.

Flotation is preferably also characterized in that froth is obtained by feeding compressed air and adding a flocculant.

Leaving a fibrous material mixture.

The remaining fibrous material mixture is preferably as free as possible of the at least one dye.

This process may be repeated depending on the desired whiteness of the new paper.

If the new paper should be light gray or white, the fiber material mixture can be further bleached by oxygen or hydrogen peroxide after deinking.

In addition, it is preferable to mix fresh fibers (primary or secondary fibers) into the fibrous material mixture, because after five to seven recycling runs, the individual fibers are typically too short and brittle to ensure recycled paper stability.

As primary cellulose, fibers such as spruce and pine, and short-fiber cellulose such as birch, beech, poplar, oak, eucalyptus, or mixtures thereof can be considered.

As secondary cellulose, all known secondary celluloses can be theoretically considered.

The method for decoloring a thermosensitive recording material of the present invention is preferably further characterized by the steps of:

i) Providing a mixture of the thermal recording material and at least one further paper, in particular at least one broke, wherein a certain amount of the at least one further paper, in particular the at least one broke,

ii) treating a sample of the mixture according to INGEDE method 11 (month 1, volume 2 of 2017),

iii) The following score values were determined from the print product recyclability, deinking ability scores:

a) The brightness Y is at most 35 minutes,

b) The color coefficient a in the CIELAB system is at most 20 minutes,

d) Degree of dye removal (printing ink removal) IE up to 10 minutes, and

e) The filtrate became deep deltay for at most 10 minutes,

wherein the sum of all fractions is in the range from 0 to 100, preferably in the range from 51 to 70, particularly preferably in the range from 71 to 100, and/or preferably no individual fraction value is negative,

iv) if a sample of the mixture has reached a predetermined fractional value, decolorizing the mixture with a deinking process as described above to obtain a fibrous material mixture, or

If the sample has not reached the predetermined score value, restarting step i) with the addition of a further amount of at least one paper.

The invention also relates to a fibrous material mixture obtainable according to the above method.

The present invention relates to a method for preparing recycled paper, said method comprising the steps of:

-decolorizing the thermosensitive recording material according to the above method to obtain a fibrous material mixture, and

-preparing recycled paper comprising said fibrous material mixture, preferably with the addition of further primary or secondary fibrous material or waste paper fibrous material, comprising compacting and dewatering the fibrous material mixture optionally comprising said further primary or secondary fibrous material or waste paper fibrous material.

Accordingly, all definitions and designs of the thermosensitive recording material and the method for decoloring thermosensitive recording material are similarly applicable to the method for producing recycled paper.

As waste paper, all known waste paper can be theoretically considered.

The fibrous material stream preferably comprises cellulose authenticated according to FSC and PFSC.

Recycled paper making processes involving compaction and dewatering of a mixture of fibrous materials are generally known to those skilled in the art and are preferably characterized by the following features.

A stream of fibrous material is first provided.

This fibrous material flow is preferably guided into at least one fibrous material feeder (Faserstoffauflauf), into at least one screening section for forming a fibrous material web, into at least one pressing section and into at least one drying section with a drying group in this order.

The material feeder is generally a spray head by means of which a stream of fibrous material is applied uniformly in terms of quantity and texture to an endless, surrounding screen through which solids are separated from the water fraction. During the dewatering process, a uniform fibrous mat is formed on the screen, which is the initial basis for the later paper.

The fibre mats produced in the screening section are preferably further dewatered in the press section. For this purpose, it is usually extruded with the support of the felt. This can be done, for example, between two oppositely pressed rolls. The felt used here has the function of transporting the belt through the press section without interference and of receiving the water pressed out in the press nip.

The dryer section generally consists essentially of a steam heated cylinder which is brought into contact with the paper web to heat it until the water still in the paper web is thereby evaporated (except for the desired final humidity). These successive drying cylinders are preferably combined into a so-called drying group. These drying groups may be steamed in different ways to enable control of the drying process.

The fibre material web may then in some cases first be smoothed and then fed into a winding process, so that it can be stored and/or transported more easily.

The invention also relates to a recycled paper obtainable according to the above method.

Accordingly, all definitions and designs of the thermosensitive recording material, the method for decoloring thermosensitive recording material, and the method for preparing recycled paper are similarly applicable to recycled paper that can be obtained according to the above-described method.

Particularly preferred embodiments of the present invention will be explained in detail below.

A particularly preferred first embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, a coloring layer applied thereto, and a thermosensitive layer on the coloring layer.

In this first embodiment, the tape-like carrier material comprises paper.

In this first embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

Alternatively, in the colored layer, carbon black may be contained in an amount of 2 to 24 wt%, preferably 2 to 19 wt%, particularly preferably 10 to 24 wt%, or 10 to 19 wt% with respect to the total solid content of the colored layer.

In another embodiment, carbon black is contained in the colored layer in an amount of less than 2% by weight relative to all thermosensitive recording materials.

In this first embodiment, the thermosensitive layer includes the above-mentioned embodiments.

A particularly preferred second embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, an insulating layer applied thereto, a coloring layer applied to the insulating layer, and a thermosensitive layer on the coloring layer.

In this second embodiment, the tape-like carrier material comprises paper.

In this second embodiment, the insulation layer comprises an insulating material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this second embodiment, the coloring layer comprises a direct dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this second embodiment, the thermosensitive layer includes the above-mentioned embodiments.

A particularly preferred third embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, a coloring layer applied thereto while being an insulating layer, and a thermosensitive layer on the coloring layer.

In this third embodiment, the tape-like carrier material comprises paper.

In this third embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this third embodiment, the colored layer which is also an insulation layer comprises a thermally insulating material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this third embodiment, the thermosensitive layer includes the above-mentioned embodiments.

A particularly preferred fourth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material with starch coated lines on both sides, a coloring layer applied thereto, and a thermosensitive layer on the coloring layer.

In this fourth embodiment, the tape-like carrier material comprises paper.

In this fourth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this fourth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

A particularly preferred fifth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

In this fifth embodiment, the tape-like carrier material comprises paper.

In this fifth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this fifth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this fifth embodiment, the protective layer comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

A particularly preferred sixth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, an insulating layer applied thereto, a coloring layer applied to the insulating layer, and a thermosensitive layer on the coloring layer. Wherein a protective layer is applied to the thermosensitive layer.

In this sixth embodiment, the tape-like carrier material comprises paper.

In this sixth embodiment, the insulation layer comprises an insulating material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this sixth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this sixth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this sixth embodiment, the protective layer preferably comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

A particularly preferred seventh embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto while being an insulating layer, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

In this seventh embodiment, the tape-like carrier material comprises paper.

In this seventh embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this seventh embodiment, the colored layer which is also an insulation layer comprises a thermally insulating material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this seventh embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this seventh embodiment, the protective layer preferably comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

A particularly preferred eighth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material with starch coated lines on both sides, a colored layer applied thereto, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

In this eighth embodiment, the tape carrier material comprises paper.

In this eighth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this eighth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this eighth embodiment, the protective layer preferably comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

A particularly preferred ninth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the underside of the tape-shaped carrier material, and a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein the thermosensitive layer has a silicone layer applied thereto.

In this ninth embodiment, the adhesive layer comprises at least one adhesive, preferably a heat curable adhesive, in particular an attachment adhesive.

In this ninth embodiment, the tape carrier material comprises paper.

In this ninth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this ninth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this ninth embodiment, the silicone-based layer comprises at least one siloxane, preferably a poly (organo) siloxane.

A tenth particularly preferred embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the underside of the tape-shaped carrier material and a barrier layer applied to the other side of the tape-shaped carrier material, a colored layer applied to the barrier layer, and a thermosensitive layer on the colored layer, wherein the thermosensitive layer has a silicone layer applied thereto.

In this tenth embodiment, the adhesive layer comprises at least one adhesive, preferably a heat curable adhesive, in particular an attachment adhesive.

In this tenth embodiment, the tape-like carrier material comprises paper.

In this tenth embodiment, the insulation layer comprises an insulating material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this tenth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this tenth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this tenth embodiment, the siliconized layer comprises at least one siloxane, preferably a poly (organo) siloxane.

A particularly preferred eleventh embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the underside of the tape-shaped carrier material, and a colored layer applied to the other side of the tape-shaped carrier material, which is simultaneously an insulating layer, and a thermosensitive layer on the colored layer, wherein the thermosensitive layer has a silicone layer applied thereto.

In this eleventh embodiment, the adhesive layer comprises at least one adhesive, preferably a heat curable adhesive, in particular an attachment adhesive.

In this eleventh embodiment, the tape-like carrier material comprises paper.

In embodiments, the colored layer comprises a direct dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe) ₃ O ₄ )。

In this eleventh embodiment, the colored layer, which is also an insulation layer, comprises a thermal insulation material, preferably kaolin, particularly preferably calcined kaolin, and mixtures thereof, or a hollow sphere pigment, particularly comprising a styrene-acrylate copolymer.

In this eleventh embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this eleventh embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this eleventh embodiment, the silicones layer comprises at least one siloxane, preferably a poly (organo) siloxane.

A twelfth particularly preferred embodiment comprises a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, an adhesive layer applied to the underside of the tape-shaped carrier material, and a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein the thermosensitive layer has a silicone layer applied thereon.

In this twelfth embodiment, the adhesive layer comprises at least one adhesive, preferably a heat curable adhesive, in particular an attachment adhesive.

In this twelfth embodiment, the tape-like carrier material comprises paper.

In this twelfth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this twelfth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this twelfth embodiment, the silicone-based layer comprises at least one siloxane, preferably a poly (organo) siloxane.

A thirteenth particularly preferred embodiment comprises a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, an adhesive layer applied to the underside of the tape-shaped carrier material, and a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer and a silicone layer is applied on the protective layer.

In this thirteenth embodiment, the adhesive layer comprises at least one adhesive, preferably a heat curable adhesive, in particular an attachment adhesive.

In this thirteenth embodiment, the tape-like carrier material comprises paper.

In this thirteenth embodiment, the colored layer comprises a substantive dye, a water-flexible dye, graphite, a sulfur dye, an iron gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

In this thirteenth embodiment, the thermosensitive layer includes the above-mentioned embodiments.

In this thirteenth embodiment, the protective layer preferably comprises at least one binder and at least one pigment, particularly preferably an inorganic pigment.

In this thirteenth embodiment, the siliconized layer comprises at least one siloxane, preferably a poly (organo) siloxane.

A particularly preferred fourteenth embodiment comprises a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto, and a thermosensitive layer on the colored layer, wherein the thermosensitive layer comprises only wax.

In this fourteenth embodiment, the tape-like carrier material comprises paper.

In this fourteenth embodiment, the embodiment includes that the colored layer comprises a direct dye, a water-flexible dye, graphite, a sulfur dye, a ferric gallate ink, an inorganic and/or organic pigment dye, and/or an iron oxide (Fe ₃ O ₄ )。

Preferred embodiments one to thirteenth detailed above with respect to the embodiments mentioned for the thermosensitive layer include, inter alia, the following embodiments:

the thermosensitive layer comprises at least one polymer microparticle having a glass transition temperature of-55 to 130 ℃, preferably 40 to 80 ℃.

The thermosensitive layer comprises at least one polymer microparticle having a core/shell structure, wherein the polymer microparticle is selected from the group consisting of: (i) A polymer microparticle having a polymer outer shell with a glass transition temperature of 40 ℃ to 800 ℃, and (ii) a polymer microparticle having a polymer inner shell with a glass transition temperature of 40 ℃ to 130 ℃ and a polymer outer shell with a glass transition temperature of-55 ℃ to 50 ℃, wherein the glass transition temperature of the polymer outer shell is preferably lower than the glass transition temperature of the polymer inner shell.

The thermosensitive layer includes at least one polymer microparticle having a melting temperature of less than 250 ℃, preferably 0 to 250 ℃.

The thermosensitive layer includes at least one polymer microparticle having an average particle diameter in a range of 0.1 to 2.5 μm.

Drawings

Different layer configurations of the exemplary thermosensitive recording material of the present invention are schematically shown in the following drawings, respectively. The composition of the individual layers is to be understood as defined above for each layer.

Fig. 1: a thermosensitive recording material has a tape-shaped carrier material, a coloring layer applied thereto, and a thermosensitive layer on the coloring layer.

Fig. 2: a thermosensitive recording material has a tape-shaped carrier material, an insulating layer applied thereto, a coloring layer applied to the insulating layer, and a thermosensitive layer on the coloring layer.

Fig. 3: a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto while being an insulating layer, and a thermosensitive layer on the colored layer.

Fig. 4: a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, a coloring layer applied thereto, and a thermosensitive layer on the coloring layer.

Fig. 5: a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

Fig. 6: a thermosensitive recording material having a tape-like carrier material, an insulating layer applied thereto, a colored layer disposed on the insulating layer, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

Fig. 7: a thermosensitive recording material having a tape-shaped carrier material, a colored layer applied thereto while being an insulating layer, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer.

Fig. 8: a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, a coloring layer applied thereto, and a thermosensitive layer on the coloring layer. Wherein a protective layer is applied to the thermosensitive layer.

Fig. 9: a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the lower side of the tape-shaped carrier material, a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein a silicone layer is applied to the thermosensitive layer.

Fig. 10: a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the lower side of the tape-shaped carrier material and an insulating layer applied to the other side of the tape-shaped carrier material, a colored layer applied to the insulating layer, and a thermosensitive layer on the colored layer, wherein a silicone layer is applied to the thermosensitive layer.

Fig. 11: a thermosensitive recording material having a tape-shaped carrier material, an adhesive layer applied to the lower side of the tape-shaped carrier material, a colored layer applied to the other side of the tape-shaped carrier material while being an insulating layer, and a thermosensitive layer on the colored layer, wherein a silicone layer is applied to the thermosensitive layer.

Fig. 12: a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, an adhesive layer applied to the lower side of the tape-shaped carrier material, a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein a silicone layer is applied on the thermosensitive layer.

Fig. 13: a thermosensitive recording material having a tape-shaped carrier material with starch coating lines on both sides, an adhesive layer applied to the lower side of the tape-shaped carrier material, a colored layer applied to the other side of the tape-shaped carrier material, and a thermosensitive layer on the colored layer, wherein a protective layer is applied on the thermosensitive layer and a silicone layer is applied on the protective layer.

Fig. 14: measurement of dynamic sensitivity of thermosensitive recording materials, wherein the support materials have different brookfield smoothness. Shown are dynamic sensitivities (optical densities (ODUs)) of three recording materials with different base papers depending on the energization energy E:

a: unrefined, smooth 210 Buick,

b: calendaring, printing in a straight line at 0.5bar, smoothing 490 Bikee s,

c: after calendering, printing straight line 2x 10bar, smoothness 1276 Buick [ s ].

Examples

The invention will be explained in detail below by means of several non-limiting examples:

the thermosensitive recording materials of the present invention (comparative examples and examples E1 to E39) were prepared with the dye and/or binder concepts according to tables 13 to 19. These materials were prepared according to example 2, wherein the ratio variations of the individual formulation components (e.g. dye ratios) were balanced by the inorganic pigment calcium carbonate.

For this purpose, a coloured layer is applied to the paper substrate by means of a curtain coater. After application, the drying process of the coated paper support is carried out in a usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (e.g., surface whiteness of thermosensitive layer or paper whiteness).

The score values also detailed in tables 13 to 19 were then obtained according to the regenage method 11 from the printed product recyclability, deinking ability scores and the thermosensitive recording materials were finally scored.

It was also tested whether the thermosensitive recording material was recyclable and had at least one of the following indexes regarding recyclability:

a) In an initial mixture consisting of 100% of wood-free, uncoated, dry-toner, duplex-printed copy paper with 5% coverage per side (cen_test Master from EN 12281), the brightness reference value only deteriorates by at most 6 minutes after flotation with 1% of heat-sensitive recording material added, and the filtrate gets deeper and deteriorates by at most 3 minutes, compared to the initial mixture without flotation of heat-sensitive recording material

b) In the initial broke mixture formed from newspapers/magazines (offset, uncoated) in a ratio of 60%/40%, the brightness reference value after flotation only deteriorated by at most 6 minutes and the filtrate became deeper and deteriorated by at most 3 minutes with the addition of 5% of the thermosensitive recording material compared to the initial mixture without floatation of thermosensitive recording material.

The test results for recyclability can be seen in the scoring or annotation columns in tables 13 to 19.

The method for decoloring a thermosensitive recording material to obtain a fibrous material mixture includes the steps of:

The thermosensitive recording materials according to the present invention were prepared with the base compositions according to tables 1 to 12. Other examples and modifications of these compositions are detailed in tables 13-19.

In all examples, a material having a density of 41 or 58g/m is used ² Is used as a carrier material for a paper substrate formed from hardwood and softwood pulps.

All weights per unit area given relate to the corresponding dried layers.

The dry content (TG) of the corresponding layer formulation was set by adding water as follows: an insulating layer (30%), a coloring layer (26%), a thermosensitive layer (20%) and a protective layer (10%).

The raw materials used were used as dispersions or as solutions having the following dry contents: ropaque HP-1055 (21%), styrene-butadiene latex (48%), dyes, especially dyes according to tables 1 to 4 (typically 45%, the amount of dye is approximately halved in the case of E1), ropaque OP-96 (30%), sodium metaborate tetrahydrate (2%), stearic amide wax (22%), silicon oxide (28%), zinc stearate (35%), polyvinyl alcohol (high viscosity) (10%), calcined kaolin (45%), precipitated calcium carbonate (58%), ammonium zirconium carbonate (9%), polyvinyl alcohol (low viscosity) (7%) and kaolin (75%).

These amounts [ wt.% ] relate to the oven dried state (otro).

1.Example 1:

in example 1, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 1: composition of each layer of the thermosensitive recording material according to example 1.

n.a.: common materials known to those skilled in the art.

To improve certain coating technical properties, further components, in particular rheology auxiliaries, such as thickeners and/or surfactants, are added to the layers. The other ingredients were added in such amounts that the sum of the weight% of the respective layers was 100 weight%. Corresponding amounts are well known to those skilled in the art.

2.Example 2:

in example 2, a starch precoat (0.5 g/m ² ) Applied to the front and back sides of the paper substrate. On the coater, a colored layer was applied to the starch-coated paper substrate by a knife coater, and a heat-sensitive layer was applied thereto by a curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 2: composition of each layer of the thermosensitive recording material according to example 2.

n.a.: common materials known to those skilled in the art.

3.Example 3:

in example 3, a starch precoat (0.5 g/m ² ) Applied to the front and back sides of the paper substrate. On a coater, a pigmented layer was applied to a starch-coated paper substrate by a knife coater at a speed of 600 m/min. The thermosensitive layer and the protective layer were applied successively on the paper coater at a speed of 900m/min by means of a single-curtain coater and/or simultaneously by means of a double-curtain coater on a starch-coated paper substrate provided with a coloured layer. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 3: composition of each layer of the thermosensitive recording material according to example 3.

n.a.: common materials known to those skilled in the art.

4.Example 4:

in example 4, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 4: composition of each layer of the thermosensitive recording material according to example 4.

n.a.: common materials known to those skilled in the art.

5.Example 5:

in example 5, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 5: composition of each layer of the thermosensitive recording material according to example 5.

n.a.: common adjuvants known to those skilled in the art.

6.Example 6:

in example 6, the barrier layer was applied to the paper substrate on a paper machine by a film press at a speed of 800 m/min. The pigmented layer and the heat sensitive layer were applied successively on the paper machine at 900m/min by means of a single-curtain coater and/or simultaneously by means of a double-curtain coater on the paper substrate provided with the barrier layer. After each application, the drying process of the correspondingly coated paper support is carried out in a conventional manner.

Table 6: composition of each layer of the thermosensitive recording material according to the embodiment.

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n.a.: common materials known to those skilled in the art.

It has been shown that the use of any mixture of scattering particles/polymer particles (e.g. styrene-acrylate copolymer) and inorganic pigments (e.g. calcined kaolin) in the barrier/coloring layer provides particular advantages in terms of improved bar code readability of the thermosensitive recording material due to the high degree of fixation of the thermosensitive layer on the coloring layer.

The mixing ratio between the scattering particles/polymer particles and the inorganic pigment is preferably in the range from 8:1 to 1:8, particularly preferably in the range from 4:1 to 1:4, relative to the amount value [ wt.% ] in the oven-dried state (otro).

These embodiments are illustrated in detail by means of the following examples (examples 7 to 12) without limiting the scope thereof.

7.Example 7:

in example 7, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 7: composition of each layer of the thermosensitive recording material according to example 7.

n.a.: common materials known to those skilled in the art.

8.Example 8:

in example 8, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 8: composition of each layer of the thermosensitive recording material according to example 8.

n.a.: common materials known to those skilled in the art.

9.Example 9:

in example 9, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 9: composition of each layer of the thermosensitive recording material according to example 9.

n.a.: common materials known to those skilled in the art.

10.Example 10:

in example 10, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 10: composition of each layer of the thermosensitive recording material according to example 10.

n.a.: common materials known to those skilled in the art.

11.Example 11:

in example 11, the color layer and the heat sensitive layer were applied sequentially to the paper substrate on a coater by a single curtain coater and/or simultaneously by a double curtain coater at a speed of 900 m/min. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 11: composition of each layer of the thermosensitive recording material according to example 11.

n.a.: common adjuvants known to those skilled in the art.

12.Example 12:

in example 12, the barrier layer was applied to the paper substrate on a paper machine by a film press at a speed of 800 m/min. The pigmented layer and the heat sensitive layer were applied successively on the paper machine at 900m/min by means of a single-curtain coater and/or simultaneously by means of a double-curtain coater on the paper substrate provided with the barrier layer. After each application, the drying process of the correspondingly coated paper support is carried out in the usual manner without adversely affecting the properties of the thermosensitive recording material of the present invention (for example the surface whiteness of the thermosensitive layer or the paper whiteness).

Table 12: composition of each layer of the thermosensitive recording material according to example 12.

n.a.: common materials known to those skilled in the art.

Table 13:

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^[1] index on recyclability:

Table 14:

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^[1] with respect to cocoaIndex of recyclability:

Table 15:

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^[1] index on recyclability:

Table 16:

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^[1] index on recyclability:

Table 17:

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table 18:

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table 19:

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7. test of recyclability of Heat-sensitive recording materials of examples E1 to E39

Examples E1 to E39 each met at least one of the following indicators regarding recyclability:

a) In an initial mixture consisting of 100% of wood-free, non-painted, dry toner double-sided-printed copy paper with 5% coverage per side (cen_test Master from EN 12281), the brightness reference value was only degraded by 6 minutes after flotation with 1% of heat-sensitive recording material added, and the filtrate was degraded 3 minutes deep,

and/or

b) In the initial used paper mixture formed of newspaper/magazine (offset printing, uncoated) at a ratio of 60%/40%, in the case of adding 5% of the thermosensitive recording material, the luminance reference value was deteriorated only 6 minutes after flotation and the filtrate became deep and deteriorated 3 minutes, compared with the initial mixture of flotation without thermosensitive recording material.

Claims

1. A thermosensitive recording material, comprising:

the carrier material in the form of a strip,

a coloring layer on one side of the tape-shaped carrier material, and

a heat sensitive layer on the colored layer such that the colored layer is at least partially obscured,

wherein the heat-sensitive layer is designed such that it becomes transparent by the action of local heat, so that the coloring layer located thereunder becomes visible, characterized in that the coloring layer contains at least one dye that can be removed, in particular at least one dye that can be removed in the recycling of waste paper.

2. The thermal recording material according to claim 1, characterized in that after processing the thermal recording material according to the regenae method 11, the following score values are obtained according to the print recyclability, deinking evaluation:

a) The brightness Y is at most 35 minutes,

b) The color coefficient a in the CIELAB system is at most 20 minutes,

d) Degree of dye removal (printing ink removal) IE is at most 10 minutes, and

e) The filtrate became deep deltay for at most 10 minutes,

3. A thermal recording material according to any one of the preceding claims, characterized in that the at least one removable dye, in particular removable in the recycling of waste paper, is selected from the group comprising bleachable dyes, hydrophobic dyes, hydrophobizable dyes and/or magnetic dyes.

4. The thermal recording material according to any one of the preceding claims, wherein the at least one removable dye, in particular removable in a used paper cycle, is selected from the group comprising:

carbon black pigments, in particular in amounts of up to 24% by weight, preferably up to 19% by weight,

alternative carbon black pigments, preferably having different particle sizes, morphologies, primary/secondary particle compositions and/or surface chemistries,

organic dyes, in particular organic dyes capable of bleaching,

direct dyes, in particular direct dyes,

-a reactive dye, which is a reactive dye,

disperse dyes, preferably organic and water-insoluble,

pigment dyes, in particular disperse dyes,

iron oxide, in particular Fe ₃ O ₄ ，

A sulfur dye, which is a dye of sulfur,

the activated carbon is present as a dispersion of the activated carbon,

metal complex dyes, such as iron gallate inks (iron (III) gallate),

the presence of graphite is a material of the type,

the presence of a mica group,

Combination of carbon black pigments and dark pigments, such as in particular iron oxides, in particular Fe ₃ O ₄ ，

Biobased/food dyes, such as sepia black dyes, caramel colors or lignin and/or based on hydrothermal treatment

Printing inks for dyeing (offset inks, (UV) flexo inks),

-and/or mixtures thereof.

5. A thermosensitive recording material according to any one of the preceding claims, wherein the coloured layer comprises at least one binder.

6. A thermal recording material according to any one of the preceding claims, characterized in that the at least one removable dye, in particular removable in the recycling of used paper, is crosslinked and/or bonded with the binder.

7. A thermal recording material according to any of the preceding claims, characterized in that the thermal layer comprises at least one scattering particle, in particular polymer particles, which have a glass transition temperature of-55 ℃ to 130 ℃, a melting temperature of less than 250 ℃ and/or an average particle diameter in the range of 0.1 to 2.5 μm.

8. The thermal recording material according to any one of the preceding claims, characterized in that the thermal layer comprises at least one thermal material having a melting temperature in the range of 40 to 200 ℃ and/or a glass transition temperature in the range of 40 to 200 ℃, the thermal layer preferably comprising fatty acids and/or fatty acid amides.

9. A thermal recording material according to any one of the preceding claims, characterized in that the thermal recording material has a residual humidity of 2 to 14%, preferably 3 to 8%.

10. The thermal recording material according to any one of the preceding claims, wherein the thermal recording material has a surface whiteness of 35 to 60%.

11. A thermal recording material according to any one of the preceding claims, wherein each layer applied to the tape-like carrier material has a pick smoothness at its upper side which is in each case not the side on which the tape-like carrier material is located at least just equal to or greater than the pick smoothness of the layer under which it is respectively located.

12. The thermal recording material according to any of the preceding claims, wherein an insulation layer is present between the tape-like carrier material and the coloured layer, wherein the insulation layer preferably has a brookfield smoothness of more than 50s, preferably more than 100s,

or alternatively

The coloured layer is both a coloured layer and an insulating layer, wherein the coloured layer which is also an insulating layer preferably has a brookfield smoothness of more than 50s, preferably more than 100 s.

13. The thermal recording material according to any one of the preceding claims, wherein the thermal recording material is recyclable and has at least one of the following indicators regarding recyclability:

14. A method for decolorizing a heat-sensitive recording material, in particular according to any one of claims 1 to 13, comprising a tape-shaped carrier material, a coloured layer on one side of the tape-shaped carrier material and a heat-sensitive layer on the coloured layer such that the coloured layer is at least partially obscured, wherein the heat-sensitive layer is designed such that the heat-sensitive layer becomes transparent by local thermal action such that the coloured layer located thereunder becomes visible in order to obtain a fibrous material mixture, the method comprising the steps of:

15. The method according to claim 14, characterized in that it comprises the steps of:

ii) treating a sample of said mixture according to INGEDE method 11,

iii) The following score values were determined from the print recyclability and deinking evaluation:

a) The brightness Y is at most 35 minutes,

b) The color coefficient a in the CIELAB system is at most 20 minutes,

d) Degree of dye removal (printing ink removal) IE is at most 10 minutes, and

e) The filtrate became deep deltay for at most 10 minutes,

iv) decolorizing the mixture by deinking if a sample of the mixture has reached a predetermined fractional value to obtain a fibrous material mixture, or

16. A mixture of fibrous materials obtainable by the method according to claim 14 or 15.

17. A method of making recycled paper comprising the steps of:

-decolorizing a thermosensitive recording material according to the method of any one of claims 14 or 15 to obtain a fibrous material mixture, and

18. Recycled paper obtainable by the method according to claim 17.