HK1197281B - A cellulose fibre-based substrate - Google Patents

Description

Base material based on cellulose fibres

The present application is a divisional application having an application date of 2009, 5/18, application No. 200980120941.6, the title "release liner composition, base material and method for producing base material, and surface treatment agent of base material and use of surface treatment agent".

The present invention relates to a surface treating agent, a release liner composition, a base material and a method for producing the base material. The invention also relates to the use of the surface treatment agent. The invention relates to a substrate based on cellulose fibres.

Release coatings such as silicone coatings have been used to enhance the release properties of substrates such as paper, film or plastic coated paper substrates. The silicone coating may form the release layer of the release liner, or the silicone coating may be a functional layer of baking paper (baking paper).

When high quality marking backing products (release liners) with good silicone adhesion and low silicone rub-off are desired, special attention must be paid to the quality of the non-siliconized base material. In general, high quality release liners and good control of silicone adhesion have been required. Developments in label products have resulted in more and more challenges for release liners.

The main measure of the quality of the release liner is the adhesion of the silicone coating to the base material and the lack of pinholes (pinhole) due to excessive silicone penetration. Minimization of the amount of silicone coating is also a central goal in economic terms.

It is possible to treat the surface by using physical or chemical methods. The purpose of both methods is to regulate in a controlled manner the penetration of the silicone coating into the pore structure of the base material and the adhesion of the silicone layer. When the substrate of the release liner is composed of paper, the most important physical processing technique is calendering of the paper, where heat and pressure are used to compress the fibers into a more compacted web with fewer pores.

The search for pinhole-free release liners coated with lower amounts of silicone has led to new methods of preparation. With the new manufacturing method, the quality of the release liner is improved and the silicone consumption has been reduced without sacrificing the quality of the final product. However, some new production methods can lead to problems associated with silicone fixation (anchorage), and severe rub-off of the silicone coating has been observed.

One reason for poor silicone fixation is that the speed of coating machines that have been used to form release coatings, such as release layers, has increased. This means that the compounds of the release layer must be fixed relatively quickly to the surface of the base material, i.e. the cross-linking takes place rather quickly. Furthermore, it is an object to reduce the amount of platinum catalyst, which is an contradictory object with respect to rapid crosslinking.

Publication WO2005/071161 solves the fixation problem. This publication discloses a cellulose fiber type carrier which is intended to be siliconized (siliconize). The publication suggests that the support based on cellulose fibres is grafted with at least one organic molecule having a functional group capable of creating a covalent bond with the free OH functional groups of the cellulose and comprising vinyl functional groups. Petroleum ether was used as a solvent for the grafting reagent.

However, there are also a number of disadvantages associated with the use of monomers or low reactivity molecules. They can penetrate into the carrier and, because they are volatile compounds with low molecular weight, they can have an unpleasant odor and are irritating. Unreacted monomers or low (small) reactive molecules may also migrate and thus prevent the release agent (typically a siliconizing treatment) from adhering to the surface of the substrate and thus the release layer from coming loose, i.e. being wiped off, from the surface of the substrate.

Disadvantages relating to the practical completion of grafting are that petroleum ether is used as solvent for the grafting agent; petroleum ether cannot be used industrially on paper machines because it is a volatile organic solvent. Another disadvantage related to the practical implementation is that the paper mill process is based on an aqueous system. When the monomers or low reactivity molecules are added in water, their ability to create covalent bonds is significantly reduced in a short time, as the monomers react with the water and they are thus converted into less reactive compounds. On the other hand, if volatile solvents are added to the process, expensive investments for solvent collection and recycling are required. Furthermore, the label product can be used for food packaging, and therefore any solvent or monomer residue is unacceptable.

The object of the present invention is to introduce a product that solves the above mentioned problems. Furthermore, by means of the present invention, it is possible to use new formulations, which previously were not possible.

The surface treatment agent according to the invention is characterized by what is stated in the characterizing part of the independent claim 1. The release liner composition of the present invention is characterized in what will be presented in the characterizing part of the independent claim 13. The base material is characterized by what is stated in the characterizing part of the independent claim 16. The method of producing a base material is characterized by what is stated in the characterizing part of the independent claim 24. The use of a surface treatment agent is characterized by the characterizing part of the independent claim 31.

The present invention includes the following embodiments:

1. surface treating agent, characterized in that it comprises a backbone polymer to which has been attached

-side groups or end groups selected from the structures of the general formula

(I)R¹R³R⁴O-, wherein R¹Is thatAn aldehyde or a ketone in the form of a salt,form of silane hydride or CR⁵ ₂＝CR²Unsaturated structure of the form wherein R²And R⁵Represents H, C₁...C₂₀Alkyl chain, C₁...C₂₀Alkenyl chain, C₁...C₂₀Fatty acid chains, or C₁...C₁₀Fatty acid ester chain, R³Represents a linear or branched, substituted or unsubstituted C₁...C₂₀Alkyl or alkenyl chains or-OSiR₂ ⁶O group, wherein R⁶Represents a hydroxyl group, C₁...C₂₀An alkyl or alkoxy chain, and R⁴Represents a carbonyl group (C ═ O),

(II)R¹R³o-, wherein R¹Is thatAn aldehyde or a ketone in the form of a salt,form of silane hydride or CR⁵ ₂＝CR²Unsaturated structure of the form wherein R²And R⁵Represents H, C₁...C₂₀Alkyl chain, C₁...C₂₀Alkenyl chain, C₁...C₂₀Fatty acid chains, or C₁...C₁₀Fatty acid ester chain, R³Represents a linear or branched, substituted or unsubstituted C₁...C₂₀Alkyl or alkenyl chains or-OSiR₂ ⁶O group, wherein R⁶Represents a hydroxyl group, C₁...C₂₀An alkyl or alkoxy chain, or

-is selected from compounds having the general formulaWherein R is a block of one or more repeating units of¹Is represented by C₁...C₂₀Alkyl chains, alkenyl chains or siloxane groups (-SiO-), R²And R³Represents hydrogen, hydroxy (-OH), silane hydride groupsC₁...C₂₀Alkoxy radical, C₁...C₂₀Alkenyl or unsaturated C₁...C₂₀An acyl group.

2. The surface-treating agent according to embodiment 1, characterized in that the backbone polymer is water-soluble and it is selected from polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch ester, starch ether, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum, or polyacrylamide.

3. The surface treating agent according to embodiment 1 or 2, characterized in that the pendant group is formed in the reaction with an unsaturated haloolefin such as vinyl fluoride, vinyl chloride, vinyl bromide, vinyl iodide, allyl chloride, allyl bromide, allyl fluoride, or allyl iodide.

4. The surface-treating agent according to embodiment 1 or 2, characterized in that the pendant group is formed in the reaction with a silicon atom-containing compound such as trimethoxyvinylsilane, butenyltriethoxysilane, dimethylchlorosilane, 1, 1, 3, 3-tetramethyldisiloxane, 10-undecenyldimethylchlorosilane, 1-vinyl-3- (chloromethyl) -1, 1, 3, 3-tetramethyldisiloxane, vinyldimethylsilane, vinyldimethylethoxysilane, vinyltetramethyldisiloxane, or triethoxyvinylsilane.

5. The surface-treating agent according to embodiment 1 or 2, characterized in that the side group is formed in the reaction with an acid such as acrylic acid, 2-propylacrylic acid, methacrylic acid, itaconic acid, 3-butenoic acid, 4-pentenoic acid, 2, 4-pentadienoic acid, 5-hexenoic acid, 6-heptenoic acid, 9-decenoic acid, or 10-undecenoic acid.

6. The surface treating agent according to embodiment 1 or 2, characterized in that the pendant group is formed in the reaction with an acid chloride such as acryloyl chloride, methacryloyl chloride, 4-pentenoyl chloride, or 10-undecenoyl chloride.

7. The surface treating agent according to embodiment 1 or 2, characterized in that the pendant group is formed in the reaction with an acid anhydride such as methacrylic anhydride, itaconic anhydride or 4-pentenoic anhydride.

8. The surface treating agent according to embodiment 1 or 2, characterized in that the pendant group is formed in the reaction with an acid ester, such as monoacrylate, monomethacrylate, monoitaconate, mono-3-butenoate, mono-4-pentenoate, mono-2, 4-pentaenoic acid ester, mono-5-hexenoic acid ester, mono-6-heptenoic acid ester, mono-9-decenoic acid ester, or mono-10-undecenoic acid ester.

9. The surface treating agent according to any one of the preceding embodiments, characterized in that the surface treating agent is capable of forming a chemical bond with the silicone coating.

10. The surface treating agent according to embodiment 9, characterized in that the surface treating agent is capable of forming a covalent bond with a silicone coating.

11. The surface-treating agent according to any one of the preceding embodiments 1 to 10, characterized in that it is used as it is, as a blending component in a surface-treating layer or as an additional layer on the surface of another surface-treating layer.

12. The surface-treating agent according to any one of the preceding embodiments 1 to 11, characterized in that it is used in an amount of 0.01% to 100% relative to the total weight of the surface-treating layer.

13. A release liner composition in which the adhesion of silicone is improved between a silicone coating and a surface treatment layer and thus silicone rub-off is prevented, characterised in that the improvement in adhesion is based on a polymeric surface treatment structure comprising moieties that are compatible with a substrate and/or a coating on the surface of a substrate and moieties that are reactive with or at least compatible with the silicone coating.

14. The release liner composition according to embodiment 13, characterized in that the structure of the chemically bonding-producing surface treatment agent is a terminal-or pendant-functionalized polymer or a functionalized block or graft copolymer having groups capable of reacting with the silicone coating.

15. The release liner composition according to embodiments 13 to 14, characterized in that the surface treatment layer includes the surface treatment agent according to any one of the preceding embodiments 1 to 12.

16. A base material comprising a substrate and a surface treatment layer on a surface of the substrate, characterized in that the surface treatment layer comprises the surface treatment agent according to any one of the preceding embodiments 1 to 12.

17. The base material according to embodiment 16, characterized in that the substrate consists of paper.

18. The base material according to embodiment 17, characterized in that the substrate consists of cellophane.

19. The base material according to embodiment 16, characterized in that the substrate consists of a film material.

20. The base material according to embodiment 19, characterized in that the substrate consists of a thermoplastic polymer material, ideally polyethylene terephthalate (PET), oriented polypropylene (OPP), Low Density Polyethylene (LDPE), or High Density Polyethylene (HDPE).

21. The base material according to embodiment 16, characterized in that the substrate consists of coated paper.

22. The base material according to any of the preceding embodiments 16 to 21, characterized in that it is the base material of a release liner.

23. The base material according to any one of the preceding embodiments 16 to 18, characterized in that it is a base material of a baking paper.

24. A method of producing improved adhesion between a surface treatment layer and a silicone coating on a substrate and reduced rub-off of the silicone coating, characterized in that the improvement in adhesion is based on the structure of the polymeric surface treatment applied to the substrate, the structure of the polymeric surface treatment comprising moieties that are compatible with the substrate and/or the coating on the surface of the substrate, and moieties that are reactive with the silicone coating or at least compatible with the silicone coating.

25. The method according to embodiment 24, characterized in that the surface treatment layer consists solely of the surface treatment agent.

26. The method according to embodiment 24, characterized in that the surface treatment layer is a coating composition comprising the surface treatment agent.

27. The method according to embodiments 24-26, characterized in that the surface treatment layer is applied on an uncoated substrate.

28. The method according to embodiments 24-26, characterized in that the surface treatment layer is applied on a pre-coated substrate.

29. The method according to embodiments 24-28, characterized in that the surface treatment agent forms a chemical bond with the silicone coating.

30. The method according to any of the preceding embodiments 24 to 29, characterized in that the surface treatment agent forms a covalent bond with the silicone coating.

31. Use of a surface treatment agent for improving the adhesion of a silicone coating to a base material, the structure of the polymeric surface treatment agent comprising moieties that are compatible with the substrate and/or the coating on the surface of the substrate, and moieties that are reactive with or at least compatible with silicone.

32. The use according to embodiment 31, characterized in that the surface treatment agent according to any one of the preceding embodiments 1 to 12 is used for improving the adhesion of silicone to a base material.

33. Use according to embodiment 31 or 32, characterized in that the surface treatment agent is used to form a chemical bond with the silicone coating.

34. Use according to any of the preceding embodiments 31 to 33, characterized in that the surface treatment agent is used to form covalent bonds with a silicone coating.

The present invention also includes the following embodiments:

1. a release liner base material composition comprising a paper substrate and a surface treatment layer on the surface of the paper substrate, characterized in that the rub-off of a silicone coating applied on the surface treatment layer is prevented and the adhesion of the silicone is improved by the bond formed from vinyl or silicon hydride groups in a hydrosilylation reaction or the bond created by a silicone compatibility block present in the surface treatment agent in the composition of the surface treatment layer.

2. The release liner base material composition according to embodiment 1, characterized in that the silicone compatible compound is an oligomeric or polymeric hydrocarbon or polysiloxane.

3. The release liner base material composition according to embodiment 1, characterized in that the vinyl or silane hydride groups or silicone compatible blocks present in the composition of the surface treatment layer are selected from structures having the following general formula:

wherein

R¹Representing methyl or vinyl end groups

R²Represents hydrogen or methyl;

n＝0...10，

wherein

n＝1...10，

Wherein

R³To represent

R⁴Is represented by C₁...C₄An alkyl chain;

n 1.. 20, and

R⁵represents OH or C₁...C₄An alkyl chain.

4. The release liner base material composition according to embodiment 1, characterized in that the improvement of adhesion is based on the presence of a polymeric surface treatment agent in the composition comprising a surface treatment layer of a polymeric backbone, which is preferably selected from the group of water-soluble polymers consisting of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch ester, starch ether, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum, or polyacrylamide.

5. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with an unsaturated haloolefin, such as vinyl fluoride, vinyl chloride, vinyl bromide, vinyl iodide, allyl chloride, allyl bromide, allyl fluoride, or allyl iodide.

6. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with a compound containing at least one silicon atom such as trimethoxyvinylsilane, butenyltriethoxysilane, dimethylchlorosilane, 1, 1, 3, 3-tetramethyldisiloxane, 10-undecenyldimethylchlorosilane, 1-vinyl-3- (chloromethyl) -1, 1, 3, 3-tetramethyldisiloxane, vinyldimethylsilane, vinyldimethylethoxysilane, vinyltetramethyldisiloxane, or triethoxyvinylsilane.

7. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with an acid, such as acrylic acid, 2-propylacrylic acid, methacrylic acid, itaconic acid, 3-butenoic acid, 4-pentenoic acid, 2, 4-pentadienoic acid, 5-hexenoic acid, 6-heptenoic acid, 9-decenoic acid, or 10-undecenoic acid.

8. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with an acid chloride such as acryloyl chloride, methacryloyl chloride, 4-pentenoyl chloride, or 10-undecenoyl chloride.

9. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with an acid anhydride such as methacrylic anhydride, itaconic anhydride or 4-pentenoic anhydride.

10. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent present in the composition of the surface treatment layer is formed in a reaction with an acid ester, such as monoacrylate, monomethacrylate, monoitaconate, mono-3-butenoate, mono-4-pentenoate, mono-2, 4-pentaenoate, mono-5-hexenoate, mono-6-heptenoate, mono-9-decenoate, or mono-10-undecenoate.

11. The release liner base material composition according to embodiment 1, characterized in that the surface treatment agent is used in an amount of 0.01% to 100% relative to the total weight of the surface treatment layer.

12. The release liner base material composition according to embodiment 1, characterized in that the paper substrate consists of cellophane.

13. The release liner base material composition according to embodiment 1, characterized in that the paper substrate consists of coated paper.

14. The release liner base material composition according to embodiment 1, characterized in that the surface treatment layer consists only of the surface treatment agent.

15. The release liner base material composition according to embodiment 1, characterized in that the surface treatment layer is a coating composition including the surface treatment agent.

16. The release liner base material composition according to embodiment 1, characterized in that the surface treatment layer is applied on an uncoated substrate.

17. The release liner base material composition according to embodiment 1, characterized in that the surface treatment layer is applied on a pre-coated substrate.

18. The release liner base material composition according to embodiment 1, characterized in that it is a base material of baking paper.

19. A method of producing a release liner base material composition comprising a paper substrate and a surface treatment layer on a surface of the paper substrate, characterized in that the method comprises forming the surface treatment layer at least partly consisting of a surface treatment agent comprising a bond formed from a vinyl or silane hydride group in a hydrosilylation reaction or a silicone compatibility block present in the surface treatment agent in the composition of the surface treatment layer, to improve adhesion between the surface treatment layer and a silicone coating applied on top of the surface treatment layer on the surface of the paper substrate, and to reduce rub-off of the silicone coating.

20. The method according to embodiment 19, characterized in that the improvement of adhesion is based on a functionalized polymeric surface treatment agent comprising a polymeric backbone, which is preferably selected from the group of water soluble polymers consisting of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch ester, starch ether, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum, or polyacrylamide.

21. The method according to embodiment 19 or 20, characterized in that the surface treatment layer consists only of the surface treatment agent.

22. The method according to embodiment 19 or 20, characterized in that the surface treatment layer is a coating composition comprising the surface treatment agent.

23. The method according to any of the preceding embodiments 19 to 22, characterized in that the surface treatment layer is applied on an uncoated substrate.

24. The method according to any of the preceding embodiments 19 to 22, characterized in that the surface treatment layer is applied on a pre-coated substrate.

25. The method according to any of the preceding embodiments 19 to 22, characterized in that the surface treatment agent forms a chemical bond with the silicone coating.

26. The method according to any of the preceding embodiments 19 to 22, characterized in that the surface treatment agent forms a covalent bond with the silicone coating.

27. Use of a surface treatment agent in a release liner composition for improving adhesion between a silicone coating on a paper substrate and the surface treatment layer and reducing silicone rub-off, characterized in that the surface treatment agent is based on vinyl or silane hydride groups or silicone compatibility blocks in the structure of a functionalized surface treatment agent in the release liner composition.

28. The use according to embodiment 27, characterized in that the surface treatment agent is a polymeric or oligomeric compound comprising a polymer backbone, which is preferably selected from the group of water-soluble polymers consisting of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch esters, starch ethers, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum, or polyacrylamide.

29. The use according to embodiment 27, characterized in that the surface treatment agent is used to form a chemical bond with the silicone coating.

30. The use according to embodiment 27, characterized in that the surface treatment agent is used to form covalent bonds with the silicone coating.

In describing the present invention, certain terminology will be used in a definitional manner. Fig. 1 illustrates the structure of a release liner according to the present invention. The release liner composition includes a substrate 1, a surface treatment layer 2 and a release layer 3. The substrate refers to a paper substrate, a film substrate, or a film (plastic) coated paper substrate. The paper substrate may be coated, sized or otherwise surface treated. The base material 4 is a base material including a surface treatment layer. The surface treatment layer includes a surface treatment agent comprising at least one end-or side-functionalized block or graft copolymer having groups capable of reacting with the silicone coating. The release liner 5 refers to a product comprising a substrate, a surface treatment layer on the surface of the substrate, and a silicone coating layer on top of the surface treatment layer. The silicone coating may be based on, for example, a solvent-containing silicone, a solventless silicone, a UV curable silicone, or an emulsion silicone. According to the invention, the surface-treating agent 6 forms a complete surface-treating layer, or is part of a surface-treating layer, or is spread as a primer directly on the substrate surface or on a layer (e.g. a coating or sizing agent layer) spread on the substrate surface.

The present invention provides a novel surface treatment agent and composition in which adhesion of silicone is improved and silicone rub-off is prevented. When the surface treatment agent is applied to a substrate such as paper, film or coated substrate, a base material is formed. The surface treatment layer of the base material is capable of forming covalent bonds at the interface between the silicone coating and the surface treatment layer. The improvement in adhesion is based on a structure comprising a moiety that is compatible with the substrate and/or a coating on the surface of the substrate, and a moiety that is reactive with or at least compatible with the silicone coating.

The novel surface treatment is a functionalized polymer capable of bonding to the silicone coating. This provides a major enhancement compared to the previous solutions, where the adhesion of the silicone coating has been based on weak forces and physical entanglement.

The functionalized polymer includes a polymer backbone to which functional units, such as functional groups or polymer chains, are attached. The polymer backbone may be water soluble, water dispersible, or water emulsifiable. The water-soluble polymer backbone may be obtained from a water-soluble carrier polymer, such as polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch ester, starch ether, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum (xanthan) or polyacrylamide. A preferred carrier polymer is polyvinyl alcohol.

Thanks to its structure, the polymer backbone of the carrier polymer ensures that the surface treatment agent does not penetrate deeply into the substrate; the polymer backbone comprises relatively long chains that can be retained on the surface of the substrate. Furthermore, when the support polymer is modified by grafting monomers into its structure, the final compound does not contain a substantial amount of monomers.

The polymers of the present invention formed are water-soluble, water-dispersible or water-emulsifiable graft or block copolymers. Graft copolymers are produced by attaching functional groups or polymer chains to a polymer backbone. The functional group or polymer chain is capable of forming a covalent bond and reacting with the silicon coating via a hydrosilation reaction. The block copolymer is produced by attaching a functional polymer block to the end of a backbone polymer chain to form a block copolymer structure.

In addition to the polymer backbone having functional side groups or end groups or blocks, it is possible that the surface treatment agent comprises other polymers such as water soluble polymers, which may be selected from the same polymers as the carrier polymer. It is also possible to add pigments such as organic or inorganic pigments to the surface treatment agent.

The side or end groups of the backbone polymer to which the functional group is grafted may have (I) R¹R³R⁴O-or (II) R¹R³The general formula of O-. In the general formulae (I) and (II), R¹Is thatAn aldehyde or a ketone in the form of a salt,silane hydride (silahydride) or CR in the form⁵ ₂＝CR²Unsaturated structure of the form wherein R²And R⁵Can represent H, C₁...C₂₀Alkyl chain, C₁...C₂₀Alkenyl chain, C₁...C₂₀Fatty acid chains, or C₁...C₁₀Fatty acid ester chains. In the general formulae (I) and (II), R³Denotes linear or branched, possibly substituted C₁...C₂₀Alkyl or alkenyl chains or-OSiR₂ ⁶An O group. In the general formula (I), R⁴Represents a carbonyl group (C ═ O). R bound to a silicon atom⁶The radicals may be hydroxy, C₁...C₂₀An alkyl or alkoxy chain.

The repeating structural unit of the functional block in the water-soluble skeleton polymer formed by using the functional block hasForm (a). In the general formula, R¹Is represented by C₁...C₂₀Alkyl chains, alkenyl chains or siloxane groups (-SiO-). R²And R³Can represent hydrogen, hydroxyl (-OH), silane hydride groupsC₁...C₂₀Alkoxy radical, C₁...C₂₀Alkenyl or unsaturated C₁...C₂₀An acyl group.

In practice, the side groups or end groups of the graft copolymer are formed in the reaction between the carrier polymer and the grafting material. The grafting material may be, for example, one of the materials listed below. However, the surface treatment may include the final product resulting from the reaction between the different carrier polymers and the grafted species.

The grafting species may be:

the organic molecule used as grafting material may be an unsaturated haloolefin, which is preferably vinyl fluoride, vinyl chloride, vinyl bromide, vinyl iodide, allyl chloride, allyl bromide, allyl fluoride, or allyl iodide.

The organic molecule used as grafting material may be a compound containing a silicon atom, which is preferably trimethoxyvinylsilane, butenyltriethoxysilane, dimethylchlorosilane, 1, 1, 3, 3-tetramethyldisiloxane, 10-undecenyldimethylchlorosilane, 1-vinyl-3- (chloromethyl) -1, 1, 3, 3-tetramethyldisiloxane, vinyldimethylsilane, vinyldimethylethoxysilane, vinyltetramethyldisiloxane, or triethoxyvinylsilane.

The organic molecule used as grafting material may be an acid, preferably acrylic acid, 2-propylacrylic acid, methacrylic acid, itaconic acid, 3-butenoic acid, 4-pentenoic acid, 2, 4-pentadienoic acid, 5-hexenoic acid, 6-heptenoic acid, 9-decenoic acid, or 10-undecenoic acid.

The organic molecule used as grafting material may be an acid chloride, preferably acryloyl chloride, methacryloyl chloride, 4-pentenoyl chloride or 10-undecenoyl chloride.

The organic molecule used as the grafting material may be an anhydride, which is preferably methacrylic anhydride, itaconic anhydride, or 4-pentenoic anhydride.

The organic molecule used as the grafting material may be an acid ester, which is preferably a monoacrylate, monomethacrylate, monoitaconate, mono-3-butenoate, mono-4-pentenoate, mono-2, 4-pentadienoate, mono-5-hexenoate, mono-6-heptenoate, mono-9-decenoate, or mono-10-undecenoate.

According to an advantageous embodiment of the invention, the surface treatment agent comprises a polymer skeleton comprising at least one functional end group comprising a polymer having the general formula-CH ═ CH₂Vinyl group (c) of (a). Such functional groups include, for example, vinyl, allyl, acrylic, methacrylic, 4-pentenoic and 10-undecenoic acid groups.

The support polymer which has been grafted to contain functional end groups including vinyl groups can be prepared in a reaction between a polymer, such as a water-soluble polymer, and a grafting species, such as an acid, acid chloride or acid anhydride. The degree of substitution may be up to 50 mol%. The degree of substitution need not be high because the surface treatment agent can remain on the surface of the substrate, and thus the grafted chains are available for forming bonds with a release agent such as a silicone release agent.

For example, the surface treatment agent may be obtained from the reaction between polyvinyl alcohol and a grafting substance such as 10-undecenyl chloride, 4-pentenyl chloride, methacryloyl chloride or acryloyl chloride. The other carrier polymers listed above are suitable for this purpose.

The surface treatment agent is applied to the substrate in the form of an aqueous solution, dispersion or suspension. In addition to the surface treatment agent, the solution may contain an auxiliary compound and/or inorganic particles. The substrate comprises papermaking fibers, i.e., fibers typically obtained from trees. With respect to the fiber content of the substrate, the substrate may consist essentially or entirely of chemical pulp. In addition to papermaking fibers, non-wood fibers are also possible. The surface treatment is preferably performed with a film size press, after which the surface treatment agent is dried. However, any other application method is feasible, such as roll coating, spray coating or curtain coating.

Typical substrates for release liners are paper, such as cellophane. The glassine paper refers to paper which consists of chemical pulp and which typically has a grammage of 50-150g/m². Good transparency is typically required for glassine paper, for 60g/m²Paper, measured in visible light (ISO 2469: 1994), which is typically at least 45. In the manufacture of glassine paper, the pulp is ground, so that a dense, essentially pore-free paper is obtained. Since cellophane is used as the base paper of the release paper, a non-porous surface is a requirement for good silicone coatability. The non-porous surface can be obtained by calendering and surface treatment. The paper can be first calendered and then surface treated, or first surface treated and then calendered. The calender can be a multi-nip calender or a super calender. In the calender, at least one nip is formed between a hard face roll and a soft counter surface.

After the surface treatment agent is applied to the base paper, the paper is subjected to a silicone treatment. A hydrosilation reaction occurs between the reactive surface treatment layer and the silicon-containing anti-sticking agent coated on the surface of the surface treatment layer. Thus, a strong bond is formed between the paper and the silicone coating. The surface treatment agent may be present in an amount of 0.01 to 100% by weight based on the total weight of the surface treatment layer. In other words, only 1-2mg/m is required²Or even less to prevent the wiping off of silicone.

However, other substrates than paper substrates are also possible. The substrate may be composed of a thermoplastic polymer film material such as polyesters (preferably polyethylene terephthalate (PET)) and polyolefins (preferably oriented polypropylene (OPP), Low Density Polyethylene (LDPE), or High Density Polyethylene (HDPE)). Further, the substrate may be composed of coated paper.

The use of the base material includes the use of a release liner and the use of baking paper. However, other uses are possible where good silicon adhesion is required.

In the following, the invention is illustrated by means of examples and by way of example with reference to the accompanying drawings, in which

Figure 1 shows a structure of a release liner according to the present invention,

FIG. 2 shows some advantageous mechanisms according to the present invention, and

figure 3 shows some advantageous polymer structures.

Figure 2 shows some advantageous mechanisms according to the invention. The reactive silicone coating preferably contains vinylsilane 7 and silane hydride 8 groups which crosslink the release coating in a hydrosilation reaction. When the substrate is composed of paper and it is sized by using the commonly used sizing polymers, there are hydroxyl groups that do not readily react with the reactive groups of the silicone coating. Thus, the interaction between the paper and the silicone coating occurs only through hydrogen bonds 12. However, the substrate may be coated with a surface treatment agent containing vinyl 10 or silane hydride 11 groups, which is capable of reacting with the silicone coating and forming covalent bonds 13 across the interface.

With this method, it is possible to form covalent bonds at the interface between the silicone coating and the surface treatment layer. This covalent bond is possible if the surface treatment layer contains a functional polymer capable of reacting with the silicone coating.

Fig. 3 shows some advantageous polymer structures that can be used as surface treatment layers to provide better adhesion between the silicone coating and the base material. The release liner comprises a substrate 1, which is preferably a plastic film or a substrate based on cellulose fibres. The substrate may be coated or sized to smooth the porous fiber surface and reduce the consumption of silicone coating by preventing excessive penetration of silicone into the fiber network.

The base material comprising the surface treatment layer 2 is preferably coated with a silicone layer 3 which results in easy delamination of the mark in the final product. The adhesion of the silicone layer to the base material can be improved by using a functionalized reactive polymer, i.e. a surface treatment, which polymer simultaneously comprises moieties 14 compatible with the substrate, a sizing polymer or coating on the surface of the substrate, and moieties 15-19 reactive with the silicone coating 3 or compatible with the silicone coating 3. The reactive moiety preferably contains a vinyl 15, silane hydride 17, or vinyl silane 18 end or side group capable of reacting with the silicone coating in a hydrosilation reaction. The silicone compatible moiety is preferably an oligomeric or polymeric hydrocarbon 16 or polysiloxane 19 which is capable of improving the adhesion of the silicone layer by mixing and physical bonding.

The surface treatment agent may be part of a coating or sizing applied to the surface of the substrate, or the surface treatment agent itself may be applied to the surface of the substrate. The surface treatment agent may be applied directly to the surface of the substrate, or applied on top of a coating or sizing agent.

Example 1

Polyvinyl alcohol grafted with 10-undecenyl group

Dry polyvinyl alcohol (20g, 0.3mmol, 98% hydrolysis) and N-methylpyrrolidone (400ml) were added to a cone. The polyvinyl alcohol was dissolved by heating the mixture at 120 ℃ for 4 hours. The solution was allowed to cool to room temperature with stirring. After the solution had cooled, it was placed in a stream of nitrogen and 10-undecenyl chloride (2.71g, 13.3mmol) dissolved in N-methylpyrrolidone (10ml) was added. The mixture was stirred for 15 minutes, then pyridine (35.2g, 0.44mol) and dimethylaminopyridine (5.44g, 44.5mmol) were added to the mixture. The reaction was carried out at room temperature for 48 hours under stirring and a nitrogen stream. The solution phase was collected and the solution was added to acetone using a dropping funnel to precipitate the polymer. The purification of the polymer was carried out twice by dissolving the polymer in water and precipitating it in acetone. The product was separated from the solution by centrifugation. Finally, the product was dried in vacuo at room temperature for 8 hours.

Example 2

Polyvinyl alcohol grafted with 4-pentene groups

Dry polyvinyl alcohol (20g, 0.3mmol, 98% hydrolysis) and N-methylpyrrolidone (400ml) were added to a cone. The polyvinyl alcohol was dissolved by heating the mixture at 120 ℃ for 4 hours. The solution was allowed to cool to room temperature with stirring. After the solution had cooled, it was placed in a stream of nitrogen and 4-pentenyl chloride (2.64g, 22.2mmol) dissolved in N-methylpyrrolidone (10ml) was then added. The mixture was stirred for 15 minutes, then pyridine (35.2g, 0.44mol) and dimethylaminopyridine (5.44g, 44.5mmol) were added to the mixture. The reaction was carried out at room temperature for 48 hours under stirring and a nitrogen stream. The solution phase was collected and the solution was added to acetone using a dropping funnel to precipitate the polymer. The purification of the polymer was carried out twice by dissolving the polymer in water and precipitating it in acetone. The product was separated from the solution by centrifugation. Finally, the product was dried in vacuo at room temperature for 8 hours.

Example 3

End-functionalized polyethylene glycol with allyl groups

Polyethylene glycol (30g, 15mmol) was added to a separate cone and the polymer was dried in vacuo at 105 ℃ for 3 hours. After drying in vacuo, the polyethylene glycol was dissolved with tetrahydrofuran (300ml) at room temperature, and the solution was bubbled with nitrogen for 15 minutes. Sodium hydride (0.86g, 36mmol), tetrahydrofuran (50ml) and a magnetic stirrer were added to the reaction flask. The suspension was bubbled with nitrogen for 15 minutes. The sodium hydride suspension was placed in an ice bath. The polyethylene oxide solution was transferred to the suspension under an inert atmosphere by using a nitrogen atmosphere. The reaction mixture was put into an oil bath and then refluxed for 20 hours under stirring and under a nitrogen atmosphere. Allyl bromide (4.35g, 36mmol) was added to the reaction mixture under an inert atmosphere and the mixture was refluxed under nitrogen for 20 hours with stirring. The solution phase was collected by a centrifuge and the polymer was precipitated with cyclohexane. The purification of the polymer was carried out twice by dissolving the polymer in dichloromethane and precipitating it in acetone. The product was separated from the solution by centrifugation. Finally, the product was dried in vacuo at 35 ℃ for 8 hours.

Interfacial reaction of allyl-functionalized polyethylene glycols with silane hydrides

Allyl-functionalized polyethylene glycol (2.5g, 1.25mmol) was dissolved in distilled water (100g, 5.56mol) at room temperature. The polymer model surface was prepared by casting (casting). The polymer solution was applied to a silicon wafer and the film was dried at 60 ℃ for 30 minutes. The silicone treatment composition was prepared by mixing platinum (0) -1, 3-divinyl-1, 1, 3, 3-tetramethyldisiloxane complex (25 μ l) with hydride terminated polydimethylsiloxane (5g, 8.3 mmol). The siliconizing treatment composition was applied to the polymer mold surface and then subjected to a hydrosilylation reaction at 140 ℃ for 2 minutes. The siliconized model surface was washed twice in cyclohexane (50ml) to remove unreacted hydride-terminated polydimethylsiloxane. The reacted polymer was dissolved from the silicone surface with methylene chloride (5ml) for further analysis by size exclusion chromatography. Chromatography showed that the hydrosilylation process at 140 ℃ produced a polymer structure with a higher molecular weight (roughly the sum of the molecular weights of allyl-functionalized polyethylene glycol and hydride-terminated polydimethylsiloxane), thus indicating a hydrosilylation reaction at the interface.

Example 4

Background

PVA derivatives were synthesized with double bond containing side chains attached to OH groups. In the experiments, two types of side chains were used, both comprising a double bond at one end and 5 carbons in some side chains (4-pentenoyl chloride) and 11 carbons in the other side chains (10-undecenoyl chloride). For shorter side chains, two different chemicals were prepared, in which nominally 3% and 7% of the OH groups were replaced by side chains, respectively.

Preparation of samples

Two different base papers, a and B, were used in the test. Both are normal product grades.

The PVA derivative to be tested and the commercially available PVA (degree of hydrolysis 98%) were dissolved in water (10 wt%), and the solution was applied to the surface of the paper tested with a doctor blade. About 0.2 to 0.3g/m²Is transferred to the surface of the paper.

The paper was air conditioned for at least 1 hour prior to the siliconizing treatment. The silicone used in the test was a commercially available siliconizing treatment agent, and it was prepared just before the siliconizing treatment. The silicone was applied with a doctor blade and immediately cured by infrared radiation and hot air cylinders. About 1.3g/m²The silicone of (a) is transferred onto the paper.

The rub-off as a function of time (funetion) was tested immediately after the siliconizing treatment and in the treatment in a humidity hood (T ═ 50 ℃ and humidity RH 75%). The results of the commercial marking on the production of the rub-off were studied simultaneously (acrylate adhesives).

Results

The results of the wiping are shown in Table 1. For paper a, rub-off can be detected after about 5 weeks, and for paper B already in about one week. For unmodified PVA, the change was detected after about 4 weeks, regardless of the paper used. For the PVA containing side chains with double bonds, no rub-off was detected during the test time.

Table 1: development of rubs of reference papers using unmodified PVA and modified PVA at a temperature of 50 ℃ and humidity of RH 75%, as a function of time. (1: good quality, no rub-off; 2: rub-off detected; and 3: apparent rub-off). Symbols in the table: cx: x carbons in the side chain, nominal y% of the OH groups in PVA are replaced by side chains, a: paper area without mark, and b: the area under the mark.

SUMMARY

Tests performed showed that the polymer backbone with double bonds reduced rub-off and was more resistant to belt conditions, which caused some problems in the reference paper.

Example 5

Background

PVA derivatives were synthesized with double bond side chains attached to OH groups. In this test series, one type of side chain is used, which contains a double bond at one end and contains 5 carbons (4-pentenoyl chloride). Nominally 5% of the OH groups are replaced by side chains. The number of double bonds is rather high and possibly (probable) much fewer bonds can significantly reduce the rub-off. Coating slurries, on the other hand, are typically mixtures of many components. In this test series, the modified PVA was mixed with a grade of commercially available PVA in order to test the efficiency of the modified PVA.

Preparation of samples

A product grade cellophane (paper C) was used in these tests.

Two different commercially available PVA grades A and B, and one PVA derivative, C5-5%, were used in these tests. The degree of hydrolysis of the commercially available PVA grades A and B was 99% and 98%, respectively. All of the PVA was dissolved in water and the PVA derivatives were mixed with commercially available grades of PVA in ratios of 0: 100, 1: 99, 5: 95, and 100: 0. The treatment solution was applied to the surface of the paper to be tested with a doctor blade. About 0, 1-0, 2g/m²Is transferred to the surface of the paper.

The paper was air conditioned for at least 1 hour prior to the siliconizing treatment. The siliconizing treatment agent used in the test was a commercially available siliconizing treatment agent, and it was prepared just before the siliconizing treatment. The silicone was applied with a spatula and then set upI.e. curing by infrared radiation and hot air cylinders. About 1.3g/m²The silicone of (a) is transferred onto the paper.

Rub-off as a function of time was tested immediately after the siliconizing treatment and in conditioning in a humid hood (T ═ 50 ℃ and humidity RH 75%). The results of this commercial marking on the production of the rub-off were studied simultaneously (acrylate adhesives).

Results

The rub-off results are shown in table 2. For paper C and for unmodified PVA, rub-off was detected after about 2 weeks. For mixtures containing only 1% or more of modified PVA with grafted double bonds, no rub-off was detected during the test period. It is to be noted that PVA B is a starting material for the modified PVA, and in mixtures in which only 1% of PVA B is replaced by the modified PVA, rub-off is prevented.

Table 2: development of the rub-off of the reference paper (paper C), paper C coated with unmodified PVA or paper C coated with a mixture of unmodified and modified PVA as a function of time at a temperature of 50 ℃ and at a humidity of RH 75%. (1: good quality, no rub-off; 2: rub-off detected; and 3: apparent rub-off). PVA A and PVA B have a degree of hydrolysis of 99% and 98%, respectively. Symbols in the table: cx-y: x is the number of carbons in the side chain, and in PVA the OH groups, designated y ═ are replaced by side chains, a: in the area of the paper outside the mark, and b: the area under the mark. The values after PVA A, PVA B, and C5-5% represent the portion of these chemicals in the mixture.

Summary of the invention

The tests carried out show that even small amounts (1% of the solids content) of treating agents containing a polymer backbone onto which double bonds have been grafted are effective in reducing rub-off if commercial PVA grades with a high degree of hydrolysis are used. In particular, the product is more resistant to belt conditions, in which some problems tend to be encountered in reference papers and in unmodified PVA.

Example 6

Background

Non-wiping paper is an important target for paper liners. Other important goals include a surface with smoothness, low absorption and no pinholes. Many barrier coatings are capable of providing a smooth and low-absorbency surface, but rub-off is often a problem. Commercially available and modified PVAs were mixed with two barrier polymer coatings in order to test the efficiency of the modified PVAs.

Preparation of samples

A product grade cellophane (paper C) was used in these tests.

A commercial PVA grade, a PVA derivative, C5-5%, and two barrier polymer solutions A and B were used in these experiments. The degree of hydrolysis of the commercially available PVA grades is 99%. Barrier coatings are commercially available and they are used as such. All of the PVA was dissolved in water, and then the barrier polymer, the unmodified PVA and the modified PVA were mixed in a ratio of 100: 0, 20: 80: 0, 20: 75: 5, 20: 70: 10, 20: 60: 20, 40: 60: 0, 40: 55: 5, 40: 50: 10 and 40: 20, respectively. The barrier polymers were tested in pure form and in mixtures containing 20% and 40% of them. The remaining mixture comprised mainly commercial PVA and only a small amount of modified PVA. The treatment solution was applied to the surface of the paper to be tested with a doctor blade. About 0.1-0.2g/m²The chemical treatment to be tested is transferred to the surface of the paper.

The paper was air conditioned for at least 1 hour prior to the siliconizing treatment. The siliconizing chemical used in the test was a commercially available siliconizing treatment agent, and it was prepared just before the siliconizing treatment. The silicone was applied with a doctor blade and immediately cured by infrared radiation and hot roller (cylinder). Will approximately 1.3 g-m²The silicone of (a) is transferred to the paper.

The rub-off as a function of time was tested immediately after the siliconizing treatment and in conditioning in a humid hood (T ═ 50 ℃ and humidity RH 75%). The results of the commercial marking on the production of the rub-off were studied simultaneously (acrylate adhesives).

Results

The results of the wiping are shown in Table 3. For both barrier polymers and for the mixture of barrier polymer and commercially available PVA, significant rub-off was detected immediately after the siliconizing treatment. For samples in which a small portion of the commercially available PVA was replaced with modified PVA containing grafted double bonds, the risk of rub-off was significantly reduced or completely prevented. It is to be noted that when the modified PVA is added, the amount of PVA is not changed. The amount of modified PVA required to prevent rub-off increases with the amount of barrier polymer in the solution.

Table 3: development of rub-off in a mixture containing barrier polymer A or B, commercially available PVA, and modified PVA as a function of time at a temperature of 50 ℃ and humidity of RH 75%. (1: good quality, no rub-off; 2: rub-off detected; and 3: apparent rub-off). Symbols in the table: a: in the area of the paper outside the mark, b: in the marked area, the values after the barrier polymer, PVA and M (containing grafted side chains with double bonds, modified PVA of 5 carbons, and nominally 6% of the OH groups replaced by side chains) represent the share of these chemicals in the mixture.

Summary of the invention

Tests conducted have shown that more complex polymer systems can be used to obtain better barrier properties by modifying the PVA, since rub-off is prevented with modified PVA containing grafted side chains with double bonds. The amount of modified PVA required to prevent rub-off increases with the amount of barrier polymer in the solution.

Example 7

Background

Normal coating slurries contain different components such as pigments, binders and rheology modifiers, and the effect of modified PVA is tested with this type of pigmented coating. On the other hand, there are many commercially available silicone grades, and the ultimate goal is that the modified PVA should bring a non-rub-off surface, allowing the use of better barrier coating chemicals, which was previously not possible at all because of rub-off.

Preparation of samples

A product grade cellophane base paper C was used in the test.

Commercially available pigments, PVA (degree of hydrolysis 99%), two barrier polymers a and B, hydroxymethylated cellulose (CMC), and a crosslinking agent and modified PVA containing side chains with double bonds were used in the experiments. Three different coatings were tested:

coating 1:

coating 2:

coating 3:

coatings were produced in which 7.5 parts of a commercially available PVA was replaced with a modified PVA containing a side chain having a double bond in order to test the effect of the modified PVA. The coating is applied with a doctor blade, about 1.6 to 1.8g/m²The tested coating was transferred to the surface of the paper. All papers were calendered prior to siliconizing.

The paper was air conditioned for at least 1 hour prior to the siliconizing treatment. Two commercial silicones were used in the tests (silicones a and B), which were prepared just before the siliconizing treatment. The silicone was applied with a doctor blade and immediately cured by infrared radiation and hot roller. About 1.3g/m²The silicone of (a) is transferred onto the paper.

The rub-off as a function of time was tested immediately after the siliconizing treatment and in conditioning in a humid hood (T ═ 50 ℃ and humidity RH 75%). The results of the commercial marking on the production of the rub-off were studied simultaneously (acrylate adhesives).

Results

The results of the wiping are shown in Table 4. Rub-off was detected immediately for coating 2, but after about 8 and 1 weeks for coatings 1 and 3, respectively. Silicone a was slightly more pronounced than silicone B in rub-off, but the results were quite similar. For coatings in which the commercial PVA was partially replaced by modified PVA (7.5 parts of modified PVA with side chains with double bonds, 5 carbons in the side chains and nominally 6% PVA OH groups grafted), no rub-off was detected during the test.

Table 4: development of rub-off as a function of time in a mixture containing a commercially available pigment, barrier polymer a or B, PVA, hydroxymethylated cellulose (CMC), and a crosslinking agent, and modified PVA, at a temperature of 50 ℃ and at a humidity of RH 75%. (1: good quality, no rub-off; 2: rub-off detected; and 3: apparent rub-off). The compositions of coatings 1, 2 and 3 are given above. Symbols in the table: a: in the area of the paper outside the mark, b: the area under the mark. Coating x + M-PVA means that 7.5 parts of the commercial PVA are replaced by a modified PVA containing grafted side chains with double bonds (side chains 5 carbons and nominally 6% of the OH groups are replaced by side chains).

Summary of the invention

The results show that the treatment agent having a polymer backbone containing grafted side chains with double bonds containing chemicals effectively reduces the rub-off of the pigmented coating. Modified PVA allows the use of new barrier polymers with improved surface properties and products that are more resistant to rub-off under tropical conditions.

Example 8

Background

The paper coating may include a number of layers, with one layer improving some properties while the other layer has other functions. This type of layered structure was tested, wherein the barrier layer allowed a better surface for the siliconizing treatment, i.e. a lower absorption level and a lower number of pores. Another layer is spread over the layer to reduce the risk of rub-off.

Preparation of samples

A product grade cellophane base paper C was used in the test.

Commercially available pigments, PVA a and B (99% and 98% hydrolysis, respectively), a barrier polymer a, hydroxymethylated cellulose (CMC), and a crosslinking agent and modified PVA containing side chains with double bonds were used in the experiment. Three different coatings were tested:

coating 1:

coating 2:

coating 3:

the coating was applied with a doctor blade to the surface of the paper to be tested. About 1.6-1.8g/m²The coating to be tested is transferred to the surface of the paper. After which either neat PVA B or a mixture in which 1% or 10% of the PVA B has been replaced by a modified PVA with side chains bearing double bonds is applied to the first layer with a doctor blade (approximately 0.2-0.3 g/m)²). All papers were calendered prior to siliconizing.

The paper was air conditioned for at least 1 hour prior to the siliconizing treatment. Commercial silicones for use in the tests were prepared just prior to the siliconizing treatment. The silicone was applied with a doctor blade and immediately cured by infrared radiation and hot roller. About 1.3g/m²The silicone of (a) is transferred to the paper.

The rub-off as a function of time was tested immediately after the siliconizing treatment and in conditioning in a humid hood (T ═ 50 ℃ and humidity RH 75%). The results of the commercial marking on the production of the rub-off were studied simultaneously (acrylate adhesives).

Results

The results of the rubbing-off are shown in Table 5. Rub-off was detected immediately for coatings 2 and 3, but after about 6 weeks for coating 1. If PVA B is coated on top of coating 1 or 2 or 3, rub-off occurs after about 2-3 weeks and the results do not significantly depend on the coating under the PVA B layer. For coatings in which the commercially available PVA B was partially replaced by modified PVA (1% or 10% modified PVA containing side chains with double bonds, 5 carbons in the side chain and nominally 5% PVA OH groups grafted), no rub-off was detected during the test.

Table 5: the development of the rub-off of the layered structure at a temperature of 50 ℃ and at a humidity of RH 75%, as a function of time. (1: good quality, no rub-off; 2: rub-off detected; and 3: apparent rub-off). The first layer is a mixture of commercially available pigment, barrier polymer a, PVA a, hydroxymethylated cellulose (CMC), and a cross-linking agent, and the other layer is either neat PVA B or a mixture of PVA B and modified PVA. The compositions of coatings 1, 2 and 3 are given above. Symbols in the table: a: in the area of the paper outside the mark, b: the area under the mark. The values after PVA B and M-PVA mean how many parts of the above layers contain these polymers.

Summary of the invention

The results show that even when the treatment agent is applied to the surface of the colored barrier coating, the treatment agent having a polymer backbone grafted with double bond-containing side chains is effective in reducing rub-off. A layered structure of this type can have excellent paper properties, since the barrier layer allows a low absorption level and a surface with few pinholes and the layer containing the modified PVA reduces the risk of rub-off.

Claims (9)

1. A cellulose-fibre-based substrate, at least one surface of which is coated with a surface treatment layer comprising at least one water-soluble polymer backbone, characterized in that the water-soluble polymer backbone has hydroxyl functional groups, at least a part of which has previously been reacted with at least one organic molecule comprising vinyl functional groups and aldehyde functional groups, in order to prepare a graft copolymer comprising said vinyl groups, which is capable of forming covalent bonds and of reacting with a silicone coating.

2. Cellulose fiber-based substrate according to claim 1, characterized in that the water-soluble polymer containing hydroxyl functional groups is selected from the group consisting of polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl amine, starch ester, starch ether, carboxymethyl cellulose ether, carboxymethyl cellulose ester, chitosan, xanthan gum, or polyacrylamide.

3. Cellulose fibre-based substrate according to claim 1 or 2, characterised in that the water-soluble polymer with hydroxyl functional groups is PVA.

4. Cellulose fiber-based substrate according to claim 1 or 2, characterized in that the organic molecules have the general formula (I) R¹R³R⁴O-or (II) R¹R³O-, wherein R¹Represents an aldehyde, R³Denotes linear or branched C₁...C₂₀An alkenyl chain, and R⁴Represents a carbonyl group.

5. Cellulose fiber-based substrate according to claim 1 or 2, characterized in that the group comprising a vinyl function is selected from:

vinyl, allyl, acrylate, methacrylate, 4-pentenoate, and 10-undecenoate.

6. Cellulose fibre-based substrate according to claim 1 or 2, characterised in that the amount of surface treatment agent having a water-soluble polymer backbone is 1-2mg/m²。

7. A cellulosic fibre-based substrate according to claim 1 or 2, characterised in that the amount of surface treatment agent having a water-soluble polymer backbone is 0.01-100% of the total weight of the surface treatment layer.

8. Cellulose fibre-based substrate according to claim 1 or 2, characterised in that the cellulose fibre-based substrate is paper.

9. Cellulose fiber-based substrate according to claim 1 or 2, characterized in that the cellulose fiber-based substrate has a grammage of 50-150g/m²The cellophane of (1).