Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J105/00—Adhesives based on polysaccharides or on their derivatives, not provided for in groups C09J101/00 or C09J103/00
  • C09J105/14—Hemicellulose; Derivatives thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/06—Interconnection of layers permitting easy separation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
  • B32B37/26—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
  • C09D101/08—Cellulose derivatives
  • C09D101/10—Esters of organic acids
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D105/00—Coating compositions based on polysaccharides or on their derivatives, not provided for in groups C09D101/00 or C09D103/00
  • C09D105/14—Hemicellulose; Derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J101/00—Adhesives based on cellulose, modified cellulose, or cellulose derivatives
  • C09J101/08—Cellulose derivatives
  • C09J101/10—Esters of organic acids
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/40—Adhesives in the form of films or foils characterised by release liners
  • C09J7/401—Adhesives in the form of films or foils characterised by release liners characterised by the release coating composition
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2170/00—Compositions for adhesives
  • C08G2170/40—Compositions for pressure-sensitive adhesives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2401/00—Presence of cellulose
  • C09J2401/005—Presence of cellulose in the release coating
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2405/00—Presence of polysaccharides
  • C09J2405/005—Presence of polysaccharides in the release coating

Definitions

• the present invention relates to pressure-sensitive adhesive products and the production thereof.
• the present invention concerns pressure-sensitive laminates typically comprising a first sheet of material having a front side and an opposite back side, a pressure-sensitive adhesive layer provided on the back side of said first sheet of material, and a release material having a front side and an opposite back side, said front side of said release material being releasably superimposed on said adhesive layer.
• Pressure-sensitive adhesives are adhesives that are typically applied as thin solid layers and the degree of the bond (i.e. how strongly it adheres to the any superimposed surface) is dependent on how much pressure is applied to the surface(s).
• Pressure-sensitive adhesives can be used to produce bonds that are permanent, but not creep resistant. Importantly, they can also be employed for giving rise to temporary or semi-temporary bonds.
• PSAs are frequently used supported on flexible substrates.
• pressure-sensitive adhesives are widely used in, for example, labels, stickers and note pads, tapes (e.g.
• packaging tapes for sealing various packages, such as envelope closing stripes.
• the PSAs are typically capable of being applied as dispersions, solutions or hot melts and that are converted to give rise to a rubbery, tacky film of relatively low adhesive strength and rather higher cohesive strength at service temperature.
• pressure-sensitive adhesives reference is further made to Cope B. C. (2005) Adhesive classification.
• protection is provided by releasing sheets, films, foils or strips or other materials, which at least roughly have the same area and shape as the application area of the PSA on the substrate.
• the release surface provides temporary adherence of the protecting material to the PSA to allow for peeling off of the label, sticker, tape etc. at will without damaging of the adhesive or of the protecting material.
• the release surface typically comprises a coating which provides non-stick properties, for example high smoothness and low surface energy.
• non-stick properties are attained by release layers formed from soft elastomeric coatings, for example, poly(dimethylsiloxane), urethanes, acrylic and fluorocarbons.
• soft elastomeric coatings for example, poly(dimethylsiloxane), urethanes, acrylic and fluorocarbons.
• coatings are frequently used on release papers for labels and stickers.
• the conventional coating materials are based on petrochemicals and therefore neither derived from renewable source nor biodegradable. In addition to this, the impact of any fluorocarbons on the environment has to be taken into account.
• JP2000008094 A (Nitto Denko Corp) which discloses a releasant, separator and adhesive member. The document relates to
• Hemicellulose and cellulose derivatives, such as fatty acid esters, and their uses, are disclosed in our co-pending patent applications; we refer in particular to our co-pending patent application titled “A coating and a method for preparing thereof as well as to published patent application, WO2008145828 which discloses dispersions formed by hemicellulose esters and a method of producing the same thereof.
• Talja et al. "Cellulose esters from birch kraft pulp - new biomaterials for barrier coatings", ISWFPC 2011, discusses barrier films produced by dissolving a cellulose ester in an organic solvent for coating of cardboard.
• polysaccharide derivatives of the indicated kind are capable of functioning as surface layers for release substrates in a pressure-sensitive adhesive laminates.
• the front side of the release material comprises a coating of a polysaccharide fatty acid ester which contacts with the pressure-sensitive adhesive layer and allows for release of the adherent material.
• coatings can be formed on substrates, such as fibrous webs and sheets of, for example, paper and cardboard materials.
• substrates such as fibrous webs and sheets of, for example, paper and cardboard materials.
• the coatings have advantageous properties, such as good adhesion on low weight paper substrate, flexibility, high smoothness and low surface energy.
• the present laminate is mainly characterized by what is stated in the characterizing part of claim 1.
• the method according to the present invention is characterized by what is stated in the characterized part of claim 12.
• the uses according to the present invention are characterized by what is stated in claims 18 and 19.
• the coating has advantageous properties for the release paper application, such as good adhesion on low weight paper substrate, flexibility, high smoothness and low surface energy.
• pressure and heat activated xylan fatty acid ester coatings gives coatings that have advantageous properties for the bio-based release paper applications, such as good adhesion on low weight paper substrate, flexibility, high smoothness and low surface energy.
• the coating flexibility increases handling properties.
• the coating smoothness minimized the surface area being in contact with PSA.
• the peeling force of the PSA label can decreased due to the smoothness in conjuction with low surface energy.
• the coating material in this invention is based on renewable resources and biorefmery as an alternative choice for petrochemical based products
• Figure 1 is a photograph showing two papers after peeling off of a tape with a pressure-sensitive adhesive which has been pressed against the surfaces of the papers; the paper with xylan ester coating (left) and the paper without the coating (right) attached on tape (PSA) followed by peeling of them
• PSA pressure-sensitive adhesive
• a solid thin layer is applied to a substrate to form a release surface on which the label or sticker can be applied.
• the release material protects the PSA until just prior to use.
• suitable coatings can be produced from polysaccharide derivatives, in particular hemicelluloses or cellulose fatty acid esters.
• the present technology relies, for example, on the finding that polysaccharide ester coatings prepared by dispersion coating followed by pressure and heat activation can be used as a thin solid layer with release properties.
• This technology is therefore based on renewable resource and biorefmery replacing petrochemistry derived chemicals.
• US 2,353,717 describes generally the coating of a substrate with a thermoplastic polymer by using regenerated cellulose and cellulose esters. There is no particular teaching with regard to the use of materials of the present kind for providing releasing layers.
• a laminate such as a label or sticker deposited on a release substrate, comprises the steps of
• front side of the release material is provided with a coating of a polysaccharide fatty acid ester.
• the release material is provided with a thermoplastic coating from a hemicellulose polymer or a cellulose polymer by a method comprising at least the following steps:
• hydroxyl group which can be used for forming cellulose or hemicellulose ester, - reacting hemicellulose polymer or cellulose polymer with a residue originating to hydrophobic fatty acid with an aliphatic carbon tail of 4 to 28 carbons, preferably of 6 to 22 carbons or ester thereof for obtaining hemicellulose fatty acid ester or cellulose fatty acid ester,
• a substrate such as a fibrous sheet or web
• heat and pressure is preferably applied to fix the coating to the surface of the substrate.
• the present pressure-sensitive laminates comprise generally
• a release material having a front side and an opposite back side, said front side of said release material being releasably superimposed on said adhesive layer, wherein the front side of the release material comprises a coating of a polysaccharide fatty acid ester which contacts with the pressure-sensitive adhesive layer.
• the coating comprises a layer of cellulose or hemicelluloses fatty acid ester, or a mixture thereof, applied on the front side of the release material such that it covers the part of the front side superimposed on the adhesive layer.
• the pressure-sensitive laminate can be split by removing the first sheet of material (below "sticker or label") without damage to the release material.
• the polysaccharide esters that are of particular interest are esters of cellulose or hemicelluloses.
• cellulose stands for a polysaccharide comprising a linear chain of several hundred to over ten thousand [beta(l - 4) linked D- glucose units.
• Cellulose is the structural component of the primary cell wall of green plants and can be also produced by many micro-organisms. For industrial use, cellulose is mainly obtained from wood pulp for making paper or paper board.
• hemicellulose means xylans, mannans or arabinogalactans. Depending on the source, their structure varies.
• Hemicelluloses are polysaccharides, macromolecular carbohydrates consisting of large number of monosaccharides connected to each other by glycosidic bonds. Hemicelluloses are one of the most abundant renewable biopolymers in the world. Especially wood hemicelluloses, depending on their origin, can be divided into two main components glucuronoxylan and glucomannan. The hemicellulose content in dry wood is between 20 to 35 wt-%.
• Mannans have a backbone of mannose units. Glucomannan comprises also glucose units and galactoglucomannan comprises also galactose units. Mannans are the second main components of hemicelluloses found from wood. Gluco mannans are mainly found from softwood.
• Arabinogalactan is a component of the heartwood of larches, also found in coffee beans.
• Backbone of arabinogalactans forms from galactose units which are highly branched containing also arabinose and galacturonic acid units.
• xylans there exist four main forms, viz. glucoronoxylan, arabinoglucuronoxylan, neutral arabinoxylan and heteroxylan, which differ from each other in regard to how the xylose backbone is substituted.
• One particularly preferred embodiment of the invention relates to the use in release coatings of starting materials wherein free hydroxyl groups of the polysaccharide polymer are esterified.
• esters are obtained by reacting a hemicellulose polymer or cellulose polymer with a hydrophobic fatty acid with an aliphatic carbon tail of 4 to 28 carbons, or a reactive derivative thereof (e.g. acid chloride or ester or anhydride), for obtaining the corresponding hemicellulose fatty acid ester or cellulose fatty acid ester.
• the fatty acid reactant is either saturated or unsaturated.
• the fatty acid residue of the ester is the residue of a short, medium or long chain fatty acid with a carbon backbone of 4 to 28 carbons, in particular 6 to 22 carbons, more preferably 12 to 18 carbons.
• the polysaccharide is hemicellulose which contains xylose backbone, which has been esterified with a fatty acid originating to a short, medium or long chain fatty acid with a carbon backbone of 4 to 28 carbons.
• the polysaccharide is hemicellulose which contains xylose backbone, which has been esterified with a fatty acid originating to a short, medium or long chain fatty acid with a carbon backbone of 6 to 22 carbons, more preferably 12 to 18 carbons.
• the fatty acid can be, for example, palmitic acid, laurc acid, linoleic acid or oleic acid.
• the polysaccharide ester contains hydrophobic fatty acid residues which are residues of palmitic acid (palmitoyl).
• the hemicellulose polymer is a xylan polymer
• the xylose units of the prepared xylan ester polymer have an average degree of substitution (DS) of over 0.6. Palmitoyl esters of xylan are particularly preferred.
• the present polysaccharide esters can be formulated into dispersions, in particular aqueous dispersions.
• the polysaccharide esters are added to water by the aid of a dispersion auxiliary (e.g. a colloidal protecting agent), whereby the ester compound can be dispersed in water in sufficiently fine particles in order to form a stable dispersion.
• a dispersion auxiliaries include polyvinyl alcohol (PVA), particularly PVA having a weight-average molar mass of approximately 10,000 to 115,000.
• Other dispersion auxiliaries (protective colloids) include cationic starch and hydroxyalkyl starch which may be used separately or together with PVA.
• the dispersions may contain alkylketene dimer (AKD) wax and beeswax.
• additives are incorporated into the dispersion.
• additives include pigments, sizes, fillers and plasticizers.
• Fillers are exemplified by talc, CaC0 3 , starch, kaolin, bentonite, surfactants, and pigments by titanium dioxide.
• the content of the additives are generally in the range of 0.1 to 100 % by weight, typically about 1 to 50 % by weight, for example 1 to 30 % by weight, of the polysaccharide polymer.
• bentonite is used as an additive.
• Bentonite is a montmorillonite type mineral, sometimes called as nano clay. Bentonite is dispersible into aqueous solutions without additives and is therefore suitable for use in combination with the polysaccharide ester (hemicellulose fatty acid ester or cellulose fatty acid ester) dispersed into an aqueous solution. It would appear that bentonite will improve the surface properties of the formed coating or film.
• heat and pressure are, in one embodiment, applied on the coated surface of the substrate, such as fibre web or sheet, for preparing a substrate with a coating fixed onto its surface.
• the temperature can vary freely. Typically it is in the range of 30 to 300 °C, for example 40 to 250 °C. In one embodiment, the upper limit is defined by the glass transition point of the polysaccharide polymer.
• the coating is heat-sealed to produce a heat sealed coating on a fibrous web.
• the coating of the release surface obtained as explained above, exhibits at least one of the following properties: flexibility, high smoothness and low surface energy, preferably a combination of two or more of these parameters.
• the thickness of the coating is typically in the range of 1 to 500 um, for example about 5 to 200 um, in particular about 10 to 150 um, for example about 10 to 100 um.
• the amount of coating in terms of dried solids content, is generally in the range of 0.1 to 100 g/m 2 , typically 1 to 50 g/m 2 , advantageously 5 to 30 g/m 2 .
• Pressure-sensitive adhesive for the label or sticker which can be used in the present technology include conventional compositions, such as polyisobutylene rubber, butyl rubber, rubber adhesive which comprises mixtures of polyisobutylene rubber and butyl rubber, for example dissolved in organic solvents (examples of which include benzene, toluene, xylene and hexane), an adhesive obtained by mixing such an adhesive with a tackifier (examples of which include abietic acid rosin ester, terpene-phenol copolymers and terpene-indene copolymers, and acrylic adhesives which can be produced by dissolving acrylic copolymers having glass transition points of up to -20 °C in an organic solvent such as toluene and xylene.
• organic solvents examples of which include benzene, toluene, xylene and hexane
• a tackifier examples of which include abietic acid rosin ester, terpene
• copolymers examples include 2-ethylhexyl acrylate-n-butyl acrylate copolymers and 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymers.
• the foregoing lists are by no means exhaustive.
• a novel group of pressure-sensitive adhesives disclosed in a co-pending patent application, titled “Novel uses of hemicellulose derivatives", comprises hemicellulose derivatives.
• Such adhesive compositions are formulated so that it consists essentially of the
• hemicellulose derivative as such or preferably the derivative is present in mixture with at least one second component.
• the at least one second components is typically selected from the group of cohesive compounds, in particular components having a higher molecular weight than the hemicellulose derivative, and softeners.
• the cohesive compound is present in a concentration of up to 50 % by weight.
• the hemicellulose derivative forms about 1 to 99 % of the total weight of the composition, typically it forms about 10 to 85, preferably about 20 to 75 % of the total weight of the composition.
• cohesive components having higher molecular weight, forming jointly up to 75 % of the total weight, in particular about 25 to 70 % of the total weight of the composition.
• the hemicellulose derivative is a derivative, in particular chemical derivative, of xylan or galactoglucomannan or glucomannan.
• Preferred derivatives include ethers, esters and combinations thereof.
• Hydroxyalkylated derivatives are particularly preferred wherein the alkyl chain comprises 1 to 6 carbon atoms, propyl and butyl being particularly preferred.
• the ester groups can be derived from Ci to C 2 o carboxylic acids and combinations thereof, in particular Ci to C 6 or Ci 6 to C 2 o or combinations thereof.
• the derivatization in particular chemical derivatization will confer properties of thermoplasticity.
• the degree of substitution is 0.1 to 3, in particular 0.15 to 1.5.
• the average molecular weight M w of the hemicellulose is, preferably also after derivatization, 3 000 to 200 000, for example 5 000 to 100 000, in particular 7 000 to 40 000 Da.
• Molecular weights in the range of about 20 000 to 35 000 are particularly interesting since they combine good mechanical properties with softness of the material.
• hydroxyalkylated xylan or galactoglucomannan in particular hydroxypropylated xylan or galactoglucomannan
• esters of hydroxyalkylated xylan or galactoglucomannan in particular a C 2 to C 2 o, preferably a C 2 to C 6 ester thereof.
• the coated amount of the pressure-sensitive adhesive is preferably from 1 to 50 g/m 2 , typically 3 to 40 g/m 2 , advantageously 10 to 30 g/m 2 , calculated in terms of dried solid content.
• the thickness of the pressure-sensitive adhesive which has been applied and dried is normally from 10 to 300 um, for example about 10 to 50 um, if it is an acrylic adhesive, 80 to 150 um, if it is a rubber adhesive, and 50 to 300 um for hemicelluloses derivatives of the above kind.
• the product to be adhered to a substrate can be of any suitable material, but preferably comprises a laminar material, such as a sheet or web or parts thereof. Particularly interesting materials are fibrous materials and other porous materials, which allow for proper attachment of the pressure-sensitive adhesive.
• the material (first layer) is selected from paper and cardboard sheets and webs. These can have generally a grammage of 1 to 500 g/m 2 , often about 10 to 350 g/m 2 although these are no absolute ranges.
• the paper or cardboard sheets or webs can be coated or uncoated or they can have a laminated coating.
• Other equally suitable materials are films and foils and strips of polymer materials, such as thermoplastic materials, and metals, e.g. aluminium foils.
• the product (such as "labels” or “stickers") is frequently provided with a printed front side.
• the front side can also be modified in other fashions to incorporate, e.g., pigments, holograms and other security markings, as well as fields of conductivity.
• the substrate of the release material can be of any suitable material, preferably it comprises a laminar material, such as a sheet or web.
• the substrate may be comprised of one layer or it can be a laminate comprising 2 to 50 layers, for example 2 to 10 layers.
• Particularly interesting materials are fibrous materials (and other porous materials), which allow for proper adherence of the release coating.
• Another group of materials are porous materials which also allow for good adherence.
• the substrate is selected from paper and cardboard sheets and webs. These can have generally a grammage of 10 to 500 g/m 2 .
• the paper or cardboard sheets or webs can be coated or uncoated.
• Other potential materials are films and foils and strips of regenerated natural fibres or polysaccharides, such as cellofan, polymer materials, such as thermoplastic materials, or metals.
• a particularly interesting application for the present technology is in the fields of envelope and packaging closing strip, address and decoration labels and packaging tapes.
• Palmitoyl chloride was made as follows: palmitic acid (50 g) was dissolved into dichloromethane (CH 2 CI 2 ) (150 ml). To this solution dimethylformamide (DMF) (cat.) and thionyl chloride (SOCl 2 , 46.4 g) were added at room temperature and the mixture was refluxed for 2 h. Excess of SOCl 2 was evaporated and the residue was stripped with CHCI 3 (3x30ml) and dried in vacuum overnight. Product, palmitoyl chloride, was obtained as brownish oil.
• DMF dichloromethane
• SOCl 2 thionyl chloride
• Palmitoyl chloride 25 g was added dropwise at a room temperature to the solution of xylan (5g) in pyridine. After addition, temperature was raised to 105 °C for 4 hours. Solid was filtered and washed several times with hot ethanol. The white solid product was dried in vacuum overnight.
• the degree of substitution (DS) of palmitoyl xylan and starting material (xylan) were analysed by the 1H and 13 C NMR techniques.
• the glass transition temperature (Tg) was measured for xylan and palmitoylated xylan as follows: a differential scanning calorimeter (DSC, DSC20, Metttler-Toledo) was used at a heating rate of 10 °C/min and a dynamic heating tempature range from -50 to 200 °C to determine the glass transition temperature (taken from a midpoint) of the xylans before and after esterification. The samples (about 10 mg) were sealed in 40 ul aluminum pans with a pinhole on the lid. Tg was determined from the midpoint of the endothermic transition obtained from the second heating cycle. A polydispersity value (PD) gives information about molar mass distribution of a sample.
• DSC differential scanning calorimeter
• a polymer with homogeneous molar mass distribution has the PD value of 1.
• the PD of the xylan and its derivatives varied from 1.5 to 2 indicating heterogeneous molar mass distribution.
• Table 1 indicates the polydispersity for the xylan.
• the soluble matter The xylan and esterified xylan powder was weighed into a breaker followed by water addition to form a 1 % suspension. The suspension was mixed at room temperature for min by Ultra-Turrax (IKA T18 Basic) mounted with the cutter (S18N- 19G). For the first minute the cutter speed of 3500 rpm was used and then raised up to 10000 rpm for the last 4 min. The solution was centrifuged to separate the insoluble matter from the solution at 8800 rpm for 15 min. The soluble matter was determined by weighing approximately 20 g of the solution into evaporation dish followed by drying at 105 °C overnight. A fraction of the soluble matter was calculated. Table 1. A fraction of the water soluble fraction, the molar mass (Mw), the polydispersity (PD), the degree of substitution (DS) and the glass transition temperature (Tg) determined for the xylan and its derivatives.
• Mw molar mass
• PD polydispersity
• DS degree of substitution
• the obtained xylan fatty acid ester was dispersed into aqueous solution without additives.
• the xylan fatty acid ester (/2.0 g or 2.7 g) was weighed in a vial (25 x 85 mm) followed by water addition (6.3 g) to form a suspension, whose concentration was respectively 23 % and 30 %.
• the suspension was dispersed at room temperature for 5 min by Ultra-Turrax (IKA T 18 Basic) mounted with the blender (S18N-10G). For the first minute the cutter speed of 3500 rpm (set value 1) was used and then raised up to 15 000 rpm (set value 4) for the last 4 min.
• the dispersion obtained was coated on a base paper.
• Single coating layer was applied by a laboratory coater (Erichsen) mounted with spiral resulting wet thickness of 60 um.
• a rough xylan fatty acid ester layer on the base paper was obtained after an oven drying at 105 °C for 5 min.
• the coated base paper was pressed by thermo press using pre-heating at 180 °C for 2 min followed by pressing at 180 °C for 3 min under pressure of 1000 psi. As a result a smooth intact coating layer was obtained.
• the coating prepared by afore-mentioned procedures from palmitoyl xylan has enhanced barrier properties against water vapour, WVTR being 85 g ⁇ 2 d "1 at 23 °C at relative humidity of 50 %. This value is as good as that of a commercial PLA coated board (84 g m "2 d "1 ).
• a coating was produced with a non-stick surface suitable for pressure-sensitive adhesives.
• the products are also heat sealable and can emit water and oxygen after a mild heat-sealing-process.
• the release papers to be tested comprised palmitoylated xylan (cf. Table 1) reinforced with nano clay (bentonite, 10 % of the xylan derivative).
• the coated paper can be peeled easily from the pressure-sensitive adhesive (PSA) without causing damage either of them
• PSA pressure-sensitive adhesive
• suitability of the xylan ester coating has been tested successfully by hand with three different PSAs (envelope closing strip, address label and packaging tape). All the PSAs tested were visually intact after they were peeled from the xylan ester coating. Also the xylan ester coating was intact. The PSAs were peeled easily from the coating.
• the barrier coating has a brownish colour but is not a disadvantage due to the fact that the release paper is covered by a sticker. Additionally, the release paper has secondary role to protect adhesive in the sticker application prior to use. The release paper is discarded after peeling off.
• the present pressure and heat activated polysaccharide, in particular xylan, ester coatings have advantageous properties for bio-based release paper applications.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Adhesive Tapes (AREA)
• Laminated Bodies (AREA)
• Wrappers (AREA)

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Citations (4)

• 2013
  • 2013-02-13 FI FI20135133A patent/FI20135133L/fi not_active Application Discontinuation
• 2014
  • 2014-02-13 WO PCT/FI2014/050112 patent/WO2014125172A1/en active Application Filing

Patent Citations (4)

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