Heat sealable coating system suitable for sealing various types of substrates

Abstract

The present invention relates to a heat sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion comprising: a polyester or polyester mixture as type A polymer, a poly (meth) acrylate as type B polymer, a graft copolymer of type A polymer and type B polymer as type AB polymer, the present invention relates to a dispersion comprising a polyolefin or polyolefin mixture as a C-type polymer, and a graft copolymer as a CD-type polymer consisting of a C-type polymer and a poly (meth) acrylate as a D-type polymer, in which the dispersion comprises, based on the total weight of the dispersion, 30% to 60% by weight of ethyl acetate, 10% to 30% by weight of an acrylic acid ester, 10% to 30% by weight of an acrylic acid ester, and 10% to 30% by weight of an acrylic acid ester, based on the total weight of the dispersion. And wherein the dispersion comprises from 20% to 50% by weight of a type A polymer, from 10% to 20% by weight of a type B polymer, from 10% to 20% by weight of a type AB polymer, from 5% to 25% by weight of a type C polymer, and from 15% to 35% by weight of a type CD polymer, in each case, based on the total mass of the type A, type B, type C, type AB, and type CD polymers, the invention also relates to a method for sealing various types of substrates, in which a foil is coated with the coating system according to the invention.

Description

Technical Field

[0001] The present invention relates to a heat-sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion comprising: a polyester or a polyester mixture as polymer type A, a poly(meth)acrylate as polymer type B, a graft copolymer of polymer type A and polymer type B as polymer type AB, a polyolefin or a polyolefin mixture as polymer type C, and a graft copolymer of polymer type C and poly(meth)acrylate as polymer type D, wherein, based on the total weight of the dispersion, the film-forming dispersion comprises: a polyester or a polyester mixture as polymer type B, a poly(meth)acrylate as polymer type AB, a graft copolymer of polymer type A and polymer type B, a polyolefin or a polyolefin mixture as polymer type C, and a graft copolymer of polymer type C and poly(meth)acrylate as polymer type D. Dispersions comprising 30 to 60% by weight of ethyl acetate, wherein the dispersion comprises 20 to 50% by weight of polymer type A, 10 to 20% by weight of polymer type B, 10 to 20% by weight of polymer type AB, 5 to 25% by weight of polymer type C, and 15 to 35% by weight of polymer type CD, in each case based on the total mass of polymer types A, B, C, AB and CD, and a method for sealing various types of substrates, preferably aluminum foils, polyester foils or PET-coated foils, relative to polystyrene, polyester and polyvinyl chloride, wherein the foils are coated with the coating system according to the invention. Existing technology

[0002] In food technology, especially in the case of dairy products, the materials used for closing plastic containers such as yogurt pots together with conventional aluminum lids are mainly lids made of polyester, in particular polylactic acid (PLA) or amorphous polyethylene terephthalate (APET). When these lids are used for closing, they have a sealable coating which simultaneously provides an aromatic barrier for the food relative to the foil material.

[0003] Sealing of PET foil is usually achieved by polyvinyl acetate or polyethylene / polyvinyl acetate, or by polyester coating. These systems do not provide ideal heat-seal seam strength values ​​and are not transparent.

[0004] DE-A 3531036 describes a plastic foil that can be produced by coextrusion and consists of a sealing layer made of high-impact polystyrene, a block copolymer, and a lubricant. Similarly, even though APET has a very high transparency, this system cannot be produced in a transparent form. Furthermore, it is known that, with regard to the seal seam strength values ​​to be achieved, coextruded foils are less preferred than coated systems, as the former offer lower seal seam strengths, while in coated systems the coating can undergo the desired microphase separation during drying.

[0005] However, EP-A 0 406 681 correctly notes the problems of using heat-sealable plastic foils instead of aluminum foil. The limiting factor is often the significantly narrow processing window. In most cases, the processing window is very narrow, ranging from 10° C. to 20° C.; in order to guarantee problem-free production and completely satisfactory use of the sealed packages, it must be ensured that this window is adhered to fairly constantly. In filling systems with a plurality of cavities for simultaneous canning, this prerequisite cannot always be met. EP 0 406 681 addresses, in particular, the object of improving the polystyrene-based foils that can be produced by the coextrusion process of DE 35 31 036 in order to increase the processing window and process reliability. Another intention is to ensure completely satisfactory production in filling systems comprising a plurality of filling cavities. In practice, this leads to the use of relatively high sealing temperatures and places corresponding demands on the quality of the plastic foil. EP 0 406 681 meets these requirements by using a sealable plastic foil produced by a coextrusion process or by lamination, the plastic foil being made of two layers A and C and optionally including a layer B, and optionally also using a corresponding layer of an adhesion promoter D for bonding in each case two of the layers A, optionally B, and C, the plastic foil consisting of a layer of heat-sealable high-impact polystyrene A of 1% to 50%, a support layer B of up to 95%, and a layer C of high-melting plastic of 1% to 99%, the sum of the thicknesses or weights of A and optionally B and C being in each case 100. However, systems of this type are very complex to implement and are also not transparent.

[0006] EP1366128B1 describes a heat-sealing system comprising an olefin polymer or olefin polymer A, a methacrylate polymer B, a graft polymer AX composed of the aforementioned components, and a solvent or solvent mixture. The heat-sealing system is characterized by high thermal stability and a short sealing time. The solvent mixture used is a mixture of ethyl acetate, isooctane, and propyl acetate.

[0007] EP 1891174 B1 describes a heat sealing system consisting, in addition to a solvent or solvent mixture L, of an olefin polymer or olefin copolymer A, a methacrylate copolymer B, a graft polymer AB composed of the aforementioned components, a polyester C, and optionally a polymer D or an optional polymer blend DA. The heat sealing system is characterized by high heat resistance, excellent barrier properties, and short sealing times relative to various plastics and aluminum foil or PET films. The solvent mixture used is a mixture of ethyl acetate, isooctane, and propyl acetate.

[0008] EP 1 989 258 B1 describes a heat-sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion characterized in that a polymer of type A, a polyester or polyester mixture, a polymer of type B, a (meth)acrylate homopolymer or / and copolymer containing standard methacrylates and / or standard acrylates, a polymer of type AB, a graft copolymer consisting of polymers of type A and type B, and, if appropriate, a polymer of type C, an olefin polymer or olefin copolymer, a polymer of type CB, a graft polymer consisting of polymers of type C and type B, and, if appropriate, a polymer of type D and / or a polymer of type DA. A mixture of ethyl acetate, isooctane, and propyl acetate is used as the solvent mixture.

[0009] EP3140360B1 describes a one-component adhesive for heat-sealing applications for sealing polyester films, in particular polyethylene terephthalate (PET) films, to polystyrene, PVC and polyester containers. The polyester can be in particular polyethylene terephthalate (PET) or polylactic acid (PLA). The adhesive not only has good sealing strength, but also has high transparency and excellent application quality. A key aspect of the present invention is that, without the addition of an adhesion promoter, in particular an adhesion promoter based on polyester or polyvinyl chloride (PVC), sealing can be achieved, while for PS and PET containers, its barrier properties and sealing properties at least reach and sometimes exceed the performance of existing heat-sealing systems on the market. As a solvent, a mixture comprising cyclohexane and propyl acetate is used.

[0010] EP 3246370 B1 relates to a transparent, heat-sealable coating for transparent PET packaging foils, which can be provided by using a heat-sealable lacquer based on a styrene-containing copolymer, a poly(meth)acrylate, at least one polyester, and optionally a tackifier, and also to a method for sealing foils coated with this lacquer. Surprisingly, despite the use of a rubber based on a styrene-containing polymer that is optically incompatible with polyester and polymethacrylate, the transparency of the heat-sealable coating remains very high. Propyl acetate or a mixture of propyl acetate and cyclohexane is used as the solvent.

[0011] Purpose of the Invention

[0012] In order to optimize the recycling of food containers and their lids, it would be advantageous to use the same material for both the container and the lid. Many materials that can be used as containers and lids, such as polyethylene terephthalate (PET), have the disadvantage that they exhibit relatively low melting and / or decomposition temperatures, making it impossible to use heat seal coating systems that dry at temperatures much higher than 100°C for these materials.

[0013] It was therefore an object of the present invention to provide a heat-sealable coating system which can be used in a heat-sealing process in which the drying step is carried out at lower temperatures than known in the prior art.

[0014] Other inventive objects not explicitly mentioned will become apparent from the entire description, claims and examples that follow.

[0015] Achievement of the purpose of the invention

[0016] Surprisingly, the inventors have found that this object can be achieved by a heat-sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion comprising: as polymer type A a polyester or a polyester mixture, as polymer type B a poly(meth)acrylate, as polymer type AB a graft copolymer of polymer type A and polymer type B, as polymer type C a polyolefin or a polyolefin mixture, and as polymer type CD a graft copolymer composed of polymer type C and a poly(meth)acrylate as polymer type D, wherein the dispersion comprises 30 to 60% by weight of ethyl acetate.

[0017] The present invention therefore relates to a heat-sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion comprising: as polymer A, a polyester or a polyester mixture; as polymer B, a poly(meth)acrylate; as polymer AB, a graft copolymer of polymers A and B; as polymer C, a polyolefin or a polyolefin mixture; and as polymer CD, a graft copolymer composed of polymer C and a poly(meth)acrylate as polymer D, wherein the dispersion comprises 30% to 60% by weight of ethyl acetate, based on the total weight of the dispersion, and wherein the dispersion comprises 20% to 50% by weight of polymer A, 10% to 20% by weight of polymer B, 10% to 20% by weight of polymer AB, 5% to 25% by weight of polymer C, and 15% to 35% by weight of polymer CD, in each case based on the total mass of polymers A, B, C, AB and CD.

[0018] The invention also relates to a method for sealing various types of substrates, preferably aluminum foils, polyester foils or PET-coated foils, as opposed to polystyrene, polyester and polyvinyl chloride, wherein the foils are coated with the coating system according to the invention.

[0019] The use of the coating system of the present invention has the advantage that materials can be heat-sealed which have a lower decomposition temperature and melting temperature than polystyrene (PS) or polyethylene terephthalate (PET).

[0020] The coating system of the present invention can be used to prepare peelable (easy-peel) seals, especially polyethylene or polypropylene aluminum foils on polyethylene or polypropylene used in the food packaging industry.

[0021] The heat seal coating system of the present invention has the advantage that it can be used without the addition of plasticizers.

[0022] The heat seal coating system of the present invention has the further advantage that it allows drying at low temperatures, preferably below 100°C.

[0023] Low drying temperatures make it possible to apply the heat seal coating system to the foil (or film) and perform the drying step on standard coating equipment with low drying efficiency. Due to the use of low boiling point solvents, the solvent can be completely removed even at low drying temperatures.

[0024] The heat seal coating system of the present invention has the additional advantage that the low boiling point solvent (mixture) contains mainly ethyl acetate, which can be easily recovered, for example by distillation.

[0025] The products, methods and uses (methods of use) according to the present invention are described hereinafter by way of example, without intending to limit the present invention to these exemplary embodiments. When the range, general formula or category of a compound is specified below, these are intended to encompass not only the corresponding ranges or compound groups explicitly mentioned, but also all sub-ranges and sub-groups of compounds that can be obtained by omitting individual values ​​(ranges) or compounds. In the context of this specification, references to literature are cited, and their contents will fully form a part of the disclosure of the present invention, particularly with regard to the matters mentioned. Unless otherwise noted, the percentages specified below are by weight. When average values ​​are reported hereinafter, these average values ​​are numerical averages, unless otherwise noted. When the properties of a material are mentioned below, such as viscosity, etc., these properties refer to the properties of the material at 25°C, unless otherwise noted. In the case of using chemical (empirical) formulas in the present invention, the specified indices (indices) can be not only absolute numbers but also average values.

[0026] The heat-sealable coating system according to the invention, which is suitable for sealing various types of substrates, comprises a film-forming dispersion comprising:

[0027] As the polyester or polyester mixture of polymer type A,

[0028] Poly(meth)acrylate as type B polymer,

[0029] As a graft copolymer of type A polymer and type B polymer of AB type polymer,

[0030] a polyolefin or polyolefin mixture as polymer of type C, and

[0031] A graft copolymer as a CD type polymer, which is composed of a C type polymer and a poly(meth)acrylate as a D type polymer,

[0032] wherein the dispersion comprises 30 to 60 wt.% of ethyl acetate, based on the total weight of the dispersion, and wherein the dispersion comprises 20 to 50 wt.% of polymer type A, 10 to 20 wt.% of polymer type B, 10 to 20 wt.% of polymer type AB, 5 to 25 wt.% of polymer type C, and 15 to 35 wt.% of polymer type CD, in each case based on the total mass of polymer types A, B, C, AB, and CD. Preferably, the dispersion comprises 50 to 55 wt.% of ethyl acetate. It may be advantageous if the dispersion comprises 0.5 to 10 wt.%, preferably 5 to 7.5 wt.%, of cyclohexane.

[0033] Ethyl acetate and cyclohexane (if present) are preferably present in the dispersion as solvent and / or liquid phase.

[0034] It may be further advantageous if the dispersion comprises 0.0001 wt.-% to <0.1 wt.-% calcium stearate, based on the total weight of the dispersion.

[0035] It is even more advantageous if the dispersion comprises 0.0001% to <0.1% by weight of 2,6-di-tert-butyl-p-cresol, based on the total weight of the dispersion.

[0036] The dispersion of the coating system according to the invention comprises from 20% to 50% by weight, more preferably from 25% to 40% by weight, of polymer type A,

[0037] 10% to 20% by weight, more preferably 10% to 15% by weight, of polymer type B,

[0038] 10 to 20% by weight of AB type polymer,

[0039] 5 to 25 wt. %, more preferably 10 to 15 wt. % of polymer C, and

[0040] 15 to 35 wt. %, more preferably 20 to 30 wt. % of CD type polymer,

[0041] In each case, this is based on the total mass of polymer types A, B, C, AB and CD.

[0042] The proportion of the C-type polymer, including the proportion of the C-type polymer in the CD-type polymer, is preferably 5 to 40% by weight, more preferably 10 to 20% by weight, based on the total mass of the A-type, B-type, C-type, AB-type and CD-type polymers.

[0043] It can be advantageous to use a polymer as the C-polymer in which 1% to 15%, preferably 2.5% to 9%, of the carbon atoms in the backbone of the C-polymer are tertiary carbon atoms. Using such a polymer as the C-polymer can achieve greater coating flexibility, resulting in a smoother seal. The ratio of tertiary carbon atoms in the backbone can be determined using the method described in the Examples section.

[0044] In a preferred embodiment of the present invention, the aforementioned amounts of polymers of type A, type B, type C, type AB and type CD are to be understood as parts by weight rather than % by weight.

[0045] It may be advantageous if the polymer type A is a mixture of two polyesters and / or preferably the polymer type C is a mixture of two polyolefins.

[0046] The AB type polymer is preferably a graft copolymer having a polyester backbone and poly(meth)acrylate side chains.

[0047] The polymer type C is preferably EPM, hydrogenated polybutadiene, or a copolymer of ethylene and an α-olefin having 4 to 12, preferably 4 to 6, carbon atoms. The polymer type C is most preferably an ethylene-butene copolymer.

[0048] The polymers of type C preferably comprise ethylene repeat units in a proportion of 60% to 90% by weight, preferably >70% to 85% by weight, and / or preferably have a weight-average molecular weight M w It is preferably from 10,000 to 250,000 g / mol.

[0049] To prepare graft copolymers AB and CD, polymer type B is grafted onto polymer type A and polymer type D is grafted onto polymer type C simultaneously. Polymer type B and polymer type D may have different compositions or the same composition. Preferably, polymer type B and polymer type D have the same composition.

[0050] The dynamic viscosity of the heat seal coating system (adhesive) according to the present invention is preferably 200-10000 mPas, more preferably 500-5000 mPas, most preferably 1000-4000 mPas, and is determined by the method given in the Examples section.

[0051] Type A polymer

[0052] A person skilled in the art can, in principle, easily select a polyester suitable for the polymer type A of the coating composition according to the invention. A very wide range of polyesters can be used here. Selection criteria available to a person skilled in the art are, in particular, the solubility of the polyester in the corresponding solvent and, for food contact applications, the appropriate approval of the component according to food regulations.

[0053] Materials that are preferably used as polymer type A in the present invention are, on the one hand, copolyesters containing itaconic acid as monomer units (polyester A1). According to the present invention, it is also preferred to use polyesters that do not contain monomers containing polymerizable double bonds and have a number-average molar mass (Mn) of preferably greater than 5000 g / mol (polyester A2) in order to achieve adhesion to PET foils.

[0054] In a particularly preferred embodiment of the present invention, the polymer type A is a mixture of polyester A1 and polyester A2, wherein the number average molecular weight M of polyester A1 is n The polyester A2 is prepared by co-condensation of itaconic acid and has a number average molecular weight M of 700 to 5000 g / mol, preferably 2000 to 4000 g / mol. n The molecular weight of the polyester is 5,000 to 50,000 g / mol, preferably 10,000 to 35,000 g / mol, and it contains no double bonds. The AB polymer component preferably comprises only polyester A1 as the A polymer.

[0055] The preferred coating system comprises, in particular, 1 to 15% by weight, preferably 5 to 12% by weight, very particularly preferably 7 to 10% by weight, of polyester A1, including the proportion of polyester A1 in the AB polymer, and 10 to 50% by weight, preferably 20 to 40% by weight, very particularly preferably 25 to 35% by weight, of polyester A2, based on the total mass of polymers of type A, B, C, AB and CD.

[0056] As an alternative to this particularly preferred embodiment, the coating system can also comprise further polymers of type A which are completely or only to a certain extent polyesters which have been prepared by copolycondensation of itaconic acid and which particularly preferably have the same properties as the abovementioned polyesters A1.

[0057] Polyester A1 preferably has a linear or branched structure and is characterized by an OH number of 20-150 mg KOH / g, preferably 25-50 mg KOH / g, an acid number of less than 10 mg KOH / g, preferably less than 5 mg KOH / g, in particular less than 2 mg KOH / g, and a number-average molar mass of 700-5000 g / mol, preferably 2000-4000 g / mol. The hydroxyl number (OHN) is determined in accordance with DIN 53240-2. The acid number is determined in accordance with DIN EN ISO 2114. The molar mass is determined by gel permeation chromatography (GPC). The samples are characterized in tetrahydrofuran eluent in accordance with DIN 55672-1.

[0058] The itaconic acid content in the polyester A1 can preferably be 0.1 to 20 mol %, more preferably 1 to 10 mol %, very particularly preferably 2 to 8 mol %, based on the total amount of polycarboxylic acid used.

[0059] Aliphatic and / or cycloaliphatic and / or aromatic polycarboxylic acids may be present.The expression "polycarboxylic acid" refers to compounds which preferably have more than one and particularly preferably two carboxyl groups.

[0060] Examples of relatively short-chain aliphatic polycarboxylic acids are succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid and octadecanedioic acid. Examples of alicyclic polycarboxylic acids are the isomers of cyclohexanedicarboxylic acid. Examples of aromatic polycarboxylic acids are the isomers of phthalic acid and trimellitic acid. Alternatively, esterifiable derivatives thereof, such as corresponding lower alkyl esters or cyclic anhydrides, may be used instead of free polycarboxylic acids.

[0061] As polyols, aliphatic and / or cycloaliphatic and / or aromatic polyols may be present.The expression "polyol" is understood to mean a compound which preferably carries more than one, particularly preferably two, hydroxyl groups.

[0062] Examples of polyols are ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,12-dodecanediol, neopentyl glycol, butylethyl-1,3-propanediol, methyl-1,3-propanediol, methylpentanediol, cyclohexanedimethanol, trimethylolpropane, pentaerythritol, and mixtures thereof.

[0063] The term "aromatic polyol" refers to the reaction products of aromatic polyhydroxy compounds, such as hydroquinone, bisphenol A, bisphenol F, dihydroxynaphthalene, etc., with epoxides, such as ethylene oxide or propylene oxide. The polyols present may also be ether diols, i.e., oligomers or polymers based on, for example, ethylene glycol, propylene glycol, or 1,4-butanediol. Linear aliphatic diols are particularly preferred.

[0064] In addition to polyols and dicarboxylic acids, lactones can also be used to synthesize hydroxylated polyesters.

[0065] The polyesters A1 of the present invention can be prepared by using conventional methods for (poly)condensation reactions.

[0066] A1 type polyester can be traded as or Available from Evonik Operations GmbH, preferably under the trade name The most preferred product for use as polyester A1 is EP415.02.

[0067] The polyester A2, likewise preferred for the purposes of the present invention, has in particular a linear, optionally slightly branched structure and is preferably characterized by an OH value of 1-15 mg KOH / g, preferably 5-10 mg KOH / g, an acid value of less than 10 mg KOH / g, preferably less than 5 mg KOH / g, particularly preferably less than 2 mg KOH / g, preferably a number-average molar mass M n In addition, the glass transition temperature (T g ) is particularly advantageously 25° C. to 45° C., preferably 30° C. to 35° C. The glass transition temperature is measured using DSC (Differential Scanning Calorimetry) in accordance with DIN EN ISO 11357-1. The values ​​are taken from the second heating cycle.

[0068] In the case of materials of type A2 polyesters, it is preferably crucial not to use monomers containing double bonds capable of polymerizing with (meth)acrylates; this means, for example, the absence of itaconic acid. Apart from this, type A2 polyesters can be based on the same polycarboxylic acids and polyols as type A1 polyesters.

[0069] A2 type polyester can be traded as or Available from Evonik Operations GmbH, preferably under the trade name The most preferred product for use as polyester A2 is L 323.

[0070] Type B and Type D polymers

[0071] During the preparation of the dispersions of the present invention, polymer type B is formed together with the graft copolymer AB. The following description also applies to the composition of the B chain in the product component AB:

[0072] The polymer type and segment B are defined as consisting of polyacrylate sequences and / or polymethacrylate sequences. These themselves, for example in the form of corresponding homopolymers or copolymers, are soluble in the solvent system (L). Polymer B is usually composed of standard methacrylates and optionally acrylates. The type B polymer is preferably composed of MMA, butyl (meth)acrylate, ethyl (meth)acrylate and / or propyl (meth)acrylate. The expression "(meth)acrylate" here refers to methacrylate, acrylate or a mixture of methacrylate and acrylate. Other suitable monomers for type B polymers can be found, for example, in EP1989258, wherein the functional monomers also listed in this document are limited to OH functionality, acid functionality and silyl functionality in the present invention.

[0073] It is particularly preferred if polymer type B consists of more than 50% by weight, preferably 80% to 100% by weight, of MMA and / or butyl methacrylate.

[0074] The polymer may contain up to 20% by weight, preferably up to 10% by weight, and particularly preferably 0-5% by weight, of functional monomers in order to provide an additional increase in heat seal strength relative to the specific material. These functional monomers may be, for example, acids, in particular acrylic acid, methacrylic acid, or itaconic acid. Less preferred are monomers containing OH groups, such as, in particular, 2-hydroxyethyl (meth)acrylate or 3-hydroxypropyl (meth)acrylate.

[0075] Furthermore, polymer type B may contain regulators to establish the desired molecular weight range. Preferably, no regulators are present in polymer type B.

[0076] The specific proportions and compositions of polymers B are advantageously selected for the desired technical function.

[0077] Component B can also be in the form of a mixture of various poly(meth)acrylates, wherein only one of these various (meth)acrylate compositions forms component B of the polymer component AB.

[0078] The structure of the polymer type D present as a component of the polymer type CD, in particular as a side chain grafted onto the polymer type C, can be similar to that of the polymer type B. It is particularly preferred that the compositions of components B and D are identical. During the grafting reaction of the monomers of the polymer type B onto the polymer type C, homopolymers, i.e., ungrafted poly(meth)acrylates, can also be formed. In the present invention, these homopolymers are components of the polymer type B, which can, as described, be in the form of a mixture of various poly(meth)acrylates.

[0079] C-type polymer

[0080] The polyolefins corresponding to the C-type polymers used in the present invention are known per se. Preferably, these polyolefins are selected from EPM, hydrogenated polybutadiene, or copolymers of ethylene with α-olefins having 4 to 12 carbon atoms, in particular copolymers of ethylene with butene and / or octene and / or hexene. More preferably, the polyolefins are selected from ethylene-butene copolymers. The weight-average molecular weight M of the C-type polymer is w It is preferably 10,000 to 250,000, more preferably 50,000 to 230,000.

[0081] EPM is the abbreviation of ethylene-propylene copolymer. The distribution here can be basically random, but it is also advantageous to use sequential polymers with ethylene blocks. The ethylene:propylene monomer ratio can vary within certain limits, the upper limit of which can be set at about 95 mole % of ethylene and about 95 mole % of propylene. Examples of suitable EPM are described by way of example in disclosed German applications DE-A1644941, DEA1769834, DE-A1939037, DE-A1963039 and DE A2059981. The EPDM described in those references is also obviously less suitable in the present invention because these can increase the opacity of the coating.

[0082] Particularly preferred are components of type C polymers containing ethylene repeat units in a proportion of 60% to 90% by weight, preferably >70% to 85% by weight. This type of repeat unit is not limited to those obtained directly by ethylene copolymerization but can also be produced by 1,4-linking of butadiene and subsequent hydrogenation of the resulting polybutadiene. It may be advantageous for tertiary carbon atoms to comprise 1% to 15%, preferably 2.5% to 9%, of the carbon atoms in the main chain of the type C polymer.

[0083] More preferably, the polymer of type C comprises ethylene repeating units in a proportion of 60% to 90% by weight, preferably >70% to 85% by weight, and has a weight average molecular weight M w It ranges from 10,000 to 250,000.

[0084] Most preferably, the C-type polymer comprises ethylene repeating units in a proportion of 60% to 90% by weight, preferably >70% to 85% by weight, and 1% to 15%, preferably 2.5% to 9% of the carbon atoms of the main chain of the C-type polymer are tertiary carbon atoms, and the weight average molecular weight M of the C-type polymer is w It ranges from 10,000 to 250,000.

[0085] Polyolefins, in particular ethylene-butene copolymers, which can be used as polymers of type C are available from Dow Plastics under the trade name ENGAGE, preferably the products ENGAGE 7447 or 7387HM, or from Mitsui Chemicals Group under the trade name TAFMER, preferably the product TAFMER DF 640.

[0086] AB polymer

[0087] Preparation of graft polymer AB

[0088] The method of the present invention for preparing graft copolymers AB is characterized by the reaction of a suitable initiator, described below, with the graftable groups, particularly the double bonds of the itaconic acid repeating units in polymer type A, to form reactive centers for the free-radical polymerization of (meth)acrylates. The expression "reactive center" refers to a polymer chain comprising one or more initiator units for free-radical polymerization. These initiator units can be formed simultaneously or at different times. Therefore, it is likely that the itaconic acid units can only be activated after the other free radicals formed by other itaconic acid units have been deactivated by termination reactions.

[0089] Graft polymers AB are generally prepared by grafting monomers forming component B onto component A under reaction conditions suitable for this purpose. Accordingly, polymers of the AB type are preferably graft copolymers having a polyester backbone and poly(meth)acrylate side chains.

[0090] For example, a solution of the itaconic acid-containing polyester in a suitable solvent is prepared at a concentration of 10% to 65% by weight, preferably 30% to 45% by weight, which is inert under the polymerization conditions and generally has a boiling point above the process temperature. Examples of solvents that can be used are acetates, such as ethyl acetate, propyl acetate, or butyl acetate; aliphatic solvents, such as isooctane; cycloaliphatic solvents, such as cyclohexane; and carbonyl solvents, such as butanone. Ethyl acetate or cyclohexane, more preferably ethyl acetate, is preferably used as the solvent. It may also be advantageous to use a mixture comprising, or preferably consisting of, ethyl acetate and cyclohexane.

[0091] The monomers that form polymer type B are added to these polyester solutions, and polymerization is carried out by adding one or more, preferably peroxide, free radical initiators at temperatures preferably between -10°C and 100°C, over a period of preferably 4 to 8 hours. Ideally, complete conversion is achieved as much as possible. Azo compounds such as AIBN or peresters such as tert-butyl octoate are preferably used as free radical initiators. The initiator concentration depends on the desired number of grafting sites and the desired molecular weight of segment B. The initiator concentration is typically between 0.1% and 3% by weight, based on the polymer.

[0092] A chain transfer agent may also be used to determine the desired molecular weight of the B segments. Examples of suitable chain transfer agents are sulfur chain transfer agents, particularly chain transfer agents containing mercapto groups, such as those described in connection with polymer type B. The concentration of the chain transfer agent is typically 0.1% to 1.0% by weight, based on the total polymer.

[0093] Graft copolymers of AB type polymers can be synthesized not only by the solution polymerization method described above, but also by bulk polymerization. For this purpose, the polyester is dissolved in a (meth)acrylic monomer mixture before initiating free radical polymerization.

[0094] A free radical initiator may also optionally be used as an initial charge in the polyester melt, with which the monomer mixture is then mixed.

[0095] CD type polymer

[0096] Preparation of grafted polymer CD

[0097] Graft polymers CD are generally prepared as follows: a dispersion of component C is prepared, optionally with the aid of a suitable emulsifier, and monomers which give rise to polymers of type B and type D, respectively, are grafted onto this dispersion under reaction conditions suitable for this purpose. Methods for preparing suitable graft polymers of the CB and CD types are known per se: for example, they can be carried out by the transfer grafting method: (see also Houben-Weyl, Methoden der Org. Chemie [Methods of organic chemistry], vol. 1411, p. 114, HAJ Battaerd, GW Tregear, Polymer Reviews, vol. 16, Interscience (1967)).

[0098] For example, a solution of a polyolefin of polymer type C at a concentration of 10 to 50 wt. %, preferably 20 to 40 wt. %, is prepared in a suitable solvent that is inert under the polymerization conditions and generally has a boiling point above the process temperature. Examples of solvents that can be used are butyl acetate, aliphatic hydrocarbons, cycloaliphatic hydrocarbons, and aromatic hydrocarbons, and mixtures thereof. The desired monomer ratios are added to these solutions, and polymerization is carried out by adding one or more preferably peroxide free radical initiators at a temperature of 50°C to 120°C, typically over a period of 4 to 8 hours. Ideally, complete conversion is achieved as much as possible. Peresters, such as t-butyl peroctoate, are preferably used. The initiator concentration depends on the number of desired grafting sites and the desired chain length of segment D. It is typically 0.2 to 3.0 wt. %, based on the polymer.

[0099] A chain transfer agent can also be used simultaneously to determine the desired molecular weight of the chain segment D. Examples of suitable chain transfer agents are sulfur chain transfer agents, in particular those containing mercapto groups, such as those listed in the section on polymer type B. The concentration of the chain transfer agent is typically 0.1 to 1.0% by weight, based on the total polymer. Another method for preparing graft polymers CD involves hydroperoxidation of polyolefins as a first step. The hydroperoxide groups thus formed in the chain can subsequently initiate the graft polymerization of vinyl monomers (see HAJ Battaerd, GW Tregear, Polymer Reviews loc. cit.).

[0100] Preferably, the grafting of polymer type B onto polymer type A and the grafting of polymer type D onto polymer type C occur simultaneously to prepare graft copolymers AB and CD. The (statistical) composition of the side chains B and D is identical. In the present invention, the resulting homopolymer is counted as polymer type B.

[0101] Alternatively, the AB and CD polymers can also be blended, preferably synthesized simultaneously, since the dispersions thus prepared have greater stability. This can reduce phase separation problems when compared by simple blending.

[0102] In a third alternative, an AB polymer is synthesized in the presence of an already grafted CD polymer, an ungrafted (non-grafted) C polymer, and a B polymer formed during the synthesis of the CD polymer. This procedure allows the formation of additional side chains on the CD polymer and the formation of additional polymers CD. In practice, it is possible to have CD polymers with different compositions of side chains D.

[0103] In the presence of AB-type, A-type, and B-type polymers, CD-type polymers can also be similarly synthesized with similar effects.

[0104] The dispersions of the coating systems of the present invention may contain, in addition to the polymers of type A, type B, type AB, type C and type CD, further components such as adhesion promoters, stabilizers, wear improvers or antioxidants. Examples of such additional materials based on polymers are type E and E A Type polymer.

[0105] Formulations with E-type polymers are one option for improving aluminum adhesion: Improvements in Al adhesion can be observed due to priming the foil or adding 0.1 to 10 wt. %, preferably 0.1 to 5 wt. % of the adhesion improving terpolymer to the dispersion. Examples of products that can be used are VMCH (sold by Union Carbide).

[0106] Optionally, E A Type polymers to reduce possible wear during handling. For example, polyamides such as Based on the total mass of the dispersion, the E A The proportion of the cellulose-based polymer is preferably from 0.1% to 10% by weight, preferably from 0.1% to 5% by weight.

[0107] As mentioned above, further materials that may be added to the heat-sealable coating system suitable for sealing various types of substrates are auxiliaries and additives commonly used for heat sealing.

[0108] In addition to the coating composition described, a further component of the present invention is a method for sealing two materials with the aid of the coating composition of the invention.

[0109] Preparation of heat sealing system

[0110] Synthesized with AD type polymer

[0111] A dispersion of components A and C is prepared in a solvent system (L), or, if the polymer compatibility is suitable, a homogeneous solution is prepared, and the monomers forming component B (and D) are grafted onto components A and C under suitable reaction conditions. The weight ratio of A to B is generally 1:5 to 5:1. The weight ratio of A to C is generally 1:2 to 10:1, preferably 1:1 to 5:1. The preparation of the dispersion or homogeneous solution can be supported by adding a suitable emulsifier to the reaction mixture.

[0112] The total polymer content is at least 10% by weight, based on the entire dispersion, the ideal proportion in practical cases being 40% to 80% by weight, typically 45% to 60% by weight.

[0113] The method of the present invention provides a heat-sealable coating system in a dispersion that is sufficiently stable for processing methods. The dispersion is stable for at least several days, typically several weeks to several months.

[0114] The heat-sealable coating system according to the invention can be used for sealing various types of substrates and different sealing processes.

[0115] In the method according to the invention for sealing various types of substrates, a foil is coated with the heat-sealable coating system according to the invention, the coating is dried at a temperature below 100° C., preferably at a temperature of 80° C. to 98° C., and the coated side of the foil is placed onto the material to be sealed, for example made of polystyrene, polyester, PET or PVC, and sealed at a temperature of 120° C. to 220° C., preferably 160° C. to 200° C., and a pressure of 0.2 MPa to 0.6 MPa, within a period of 0.1 second to 1 second.

[0116] Preferably, the foil or film in contact with the coating system and the material to be sealed are made of the same kind of polymer, preferably polyester, more preferably polyethylene terephthalate (PET).

[0117] In another advantageous embodiment of the method according to the invention, aluminum foil, polyester or PET foil or film or PET-coated foil is used as foil or film, and a substrate made of polystyrene, polyester, PET or polyvinyl chloride is used as the material to be sealed.

[0118] Drying of the coating can be accomplished at subatmospheric pressure, preferably at a temperature above the highest boiling point of the components of the solvent system / liquid phase.

[0119] Even without further elaboration, it is believed that one skilled in the art will be able to utilize the above description to its broadest extent.Accordingly, the preferred embodiments and examples are to be understood as merely illustrative disclosures which are not intended to be limiting in any way.

[0120] The present invention will now be described in more detail with reference to examples. The examples given below illustrate the present invention in more detail without limiting the invention to the features disclosed therein. Alternative embodiments of the present invention can be obtained similarly. Example

[0121] Test method:

[0122] Solids content (SC) of heat-sealable coating system:

[0123] The solid content (SC) was determined in a drying oven by drying the heat-sealable coating system at 105° C. for 1 hour. The weight of the sample was measured before and after drying, and the solid content was calculated in wt % according to the following formula:

[0124] (Weight before drying - weight after drying) / weight before drying * 100

[0125] Dynamic viscosity:

[0126] Dynamic viscosity was measured using a Brookfield LVDV-II+ Pro viscometer at 23°C with spindle II at 6 rpm.

[0127] Molecular weight:

[0128] The molecular weight of the polymers was determined by gel permeation chromatography based on: DIN 55672-1 "Gel permeation chromatography, Part 1: Tetrahydrofuran as eluent".

[0129] column:

[0130] PSSSDV precolumn, 5μm, 5cm, 8mm

[0131] PSSSDV103, 5μm, 30cm, 8mm

[0132] PSSSDV105, 5μm, 30cm, 8mm

[0133] PSSSDV106, 5μm, 30cm, 8mm

[0134] PSSSDV107, 5μm, 30cm, 8mm

[0135] Manufacturer: PSS Polymer Standard-Service, Mainz

[0136] Eluent: Tetrahydrofuran (THF), stabilized with 250 ppm BHT (2,6-di-tert-butyl-4-methylphenol)

[0137] Flow rate: 1.0 mL / min

[0138] Oven temperature: 35°C (air)

[0139] Sample solvent: tetrahydrofuran (THF), stabilized with 1000 ppm BHT (2,6-di-tert-butyl-4-methylphenol), BHT was used as an internal standard.

[0140] Sample concentration: 2.5 g solid / l (weight 37.5 mg / 15 ml THF)

[0141] Stir and dissolve at room temperature for at least 16 hours (overnight) and filter through a disposable filter M&N Chromafil Organic Type O-45 / 25.

[0142] Injection volume: 100 μl

[0143] Detection: RI (refractive index)

[0144] Run time: 35 minutes, staggered injection 35 minutes

[0145] Calibration standard: polystyrene

[0146]

[0147] Polynom 3

[0148] Evaluation software: PSS WinGPC

[0149] Result: Polystyrene or PMMA molecular weight equivalent.

[0150] The PMMA molecular weight equivalent values ​​obtained by universal calibration using Mark-Houwink constants are: for PS: a = 0.714 / K = 0.01363; for PMMA: a = 0.688 / K = 0.01298

[0151] Mw (PS or PMMA), Mn (PS or PMMA), Mp (PS or PMMA), polydispersity D = Mw / Mn

[0152] NMR spectroscopy:

[0153] The sample was dissolved in tetrachloroethane-d2 (TCE) at 120°C, and a 13C-NMR spectrum including DEPT135 was measured.

[0154] Instrument: Bruker Avance500III HD with cryogenic probe head

[0155] Software used for evaluation: Bruker Topspin 3.5

[0156] The assessment is based on a suitable literature spectrum:

[0157] NMR Spectra of Polymers and Polymer Additives, Anita J. Brandolini, Deborah D. Hills, Marcel Dekker Inc., New York, 2000

[0158] Materials used:

[0159] Foil and can materials used:

[0160] Paper / aluminum / PET-film composite film( Amcor products)

[0161] Paper / PET-film composite (Flexpap, a product of Constantia),

[0162] PET film, thickness 36 μm, untreated, transparent)

[0163] Can materials used: Polystyrene (PS) thermoforming film from Fernholz and amorphous polyethylene terephthalate (APET) can film (from Derschlag).

[0164] AlPET (also known as AluPET) is a laminate made of aluminum foil and PET film (product of Fernholz).

[0165] 141,2,5-Dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane initiator, purchased from Nouryon.

[0166] Component A:

[0167] Table 1 lists the properties of the copolyesters (type A1 and type A2) used here as examples of component A. The materials described are semiaromatic or linear copolyesters with varying itaconic acid contents, based on the total amount of polycarboxylic acid.

[0168] Table 1: Properties of the polyesters used

[0169] Polyester Itaconic acid content <![CDATA[T g ]]> <![CDATA[M w ]]> Type A1 3.0 mol% 33℃ 15800 Type A2 0 mol% 30℃ 40900

[0170] EP 415.02 (Evonik Operations GmbH) was used as polyester of type A1.

[0171] L 323 (Evonik Operations GmbH) can be used as the A2 type polyester.

[0172] Component C:

[0173] Polyolefin samples were dissolved in tetrachloroethane-d2 (TCE) at 120°C and measured using DEPT-based 13C NMR spectra. Both ENGAGE 7447 and TAFMER DF 640 samples showed copolymers composed of ethylene (C2) and butene-1 (C4). The proportion of C4 was identical for both samples: 83 mol% (71 wt%) C2 and 17 mol% (29 wt%) C4.

[0174] TAFMER DF 640 is available from Mitsui Chemicals Group, and

[0175] ENGAGE 7447 and ENGAGE HM 7387 are commercially available from DOW Plastics.

[0176] Components B and D:

[0177] The starting materials for preparing components B and D are methyl methacrylate and butyl methacrylate.

[0178] Preparation of heat seal coating system

[0179] Invention Example 1

[0180] In a jacketed vessel with attached thermostat, reflux condenser, blade stirrer and internal thermometer, 39.3 g of TAFMER DF 640 and 64.2 g of ENGAGE 7447 were used as initial charge, added to 140.0 g of ethyl acetate and 50.5 g of cyclohexane (CH3) and stirred at 75° C. until the material dissolved.

[0181] A mixture of 59.7 g of A1 polyester (ethyl acetate solution), 116.4 g of A2 polyester, and 140.0 g of ethyl acetate was stirred at 75° C. for 2 hours. After these 2 hours, 0.42 g of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane and 5.0 g of ethyl acetate were added. After stirring at 75° C. for 10 minutes, a mixture of 1.27 g of 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane ( A mixture of 77.6 g of methyl methacrylate and 77.6 g of butyl methacrylate was added to the system at 75° C. over a period of 1.5 h. After the addition was complete, 0.34 g of 141 was added twice with an interval of 1 hour between each addition, and the mixture was stirred for a further 4 h at 75° C. The mixture was finally diluted with 120.0 g of ethyl acetate for viscosity adjustment.

[0182] Invention Example 2

[0183] In a jacketed vessel equipped with a thermostat, reflux condenser, blade stirrer, and internal thermometer, 39.3 g of TAFMER DF 640 and 64.2 g of ENGAGE 7447 were initially charged to 140.0 g of ethyl acetate and 50.5 g of cyclohexane (CH2) and stirred at 75°C until the materials dissolved. A mixture of 59.7 g of polyester type A1 (in ethyl acetate) and 116.4 g of polyester type A2 and 140.0 g of ethyl acetate was stirred at 75°C for 2 hours. After these 2 hours, 0.52 g of tert-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added. After stirring at 75°C for 10 minutes, a mixture of 77.6 g of methyl methacrylate and 77.6 g of butyl methacrylate, mixed with 1.56 g of tert-butyl peroxy-2-ethylhexanoate, was metered into the system at 75°C over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, another 0.51 g of tert-butyl peroxy-2-ethylhexanoate was added twice with an interval of 1 hour between additions, and the mixture was stirred for a further 4 h at 75° C. Finally, the mixture was diluted with 120.0 g of ethyl acetate for viscosity adjustment.

[0184] Invention Example 3

[0185] In a jacketed vessel equipped with a thermostat, reflux condenser, blade stirrer, and internal thermometer, 39.3 g of TAFMER DF 640 and 64.2 g of ENGAGE 7447 were initially charged to 140.0 g of ethyl acetate and 50.5 g of cyclohexane (CH2) and stirred at 75° C. until the materials dissolved. A mixture of 59.7 g of polyester type A1 (in ethyl acetate) and 116.4 g of polyester type A2 and 140.0 g of ethyl acetate was stirred at 75° C. for 2 hours. After these 2 hours, 0.78 g of tert-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added. After stirring at 75° C. for 10 minutes, a mixture of 77.6 g of methyl methacrylate and 77.6 g of butyl methacrylate, mixed with 2.33 g of tert-butyl peroxy-2-ethylhexanoate, was metered into the system at 75° C. over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, another 0.62 g of tert-butyl peroxy-2-ethylhexanoate was added twice with an interval of 1 hour between additions, and the mixture was stirred for a further 4 h at 75° C. Finally, the mixture was diluted with 120.0 g of ethyl acetate for viscosity adjustment.

[0186] Invention Example 4

[0187] In a pressure vessel with attached thermostat, blade stirrer and internal thermometer, 31.5 g TAFMERDF 640 and 51.3 g ENGAGE 7447 were used as initial charge, added to 100.0 g ethyl acetate and 48.0 g cyclohexane (CH2) and stirred at 85°C until the material dissolved.

[0188] A mixture of 47.8 g of A1 polyester (ethyl acetate solution), 93.1 g of A2 polyester, and 120.0 g of ethyl acetate was stirred at 85°C for 2 hours. After these 2 hours, 0.31 g of t-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added. After stirring at 85°C for 10 minutes, a mixture of 62.1 g of methyl methacrylate and 62.1 g of butyl methacrylate mixed with 0.93 g of t-butyl peroxy-2-ethylhexanoate was metered into the system at 85°C over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, 0.25 g of t-butyl peroxy-2-ethylhexanoate was added twice, with an interval of 1 hour between additions, and the mixture was stirred at 85°C for a further 5 hours. Finally, the mixture was diluted with 100.0 g of ethyl acetate to adjust the viscosity.

[0189] Invention Example 5

[0190] In a pressure vessel with connected thermostat, blade stirrer and internal thermometer, 31.5 g TAFMERDF 640 and 51.3 g ENGAGE 7447 were used as initial charge, added to 100.0 g ethyl acetate and 48.0 g cyclohexane (CH2) and stirred at 95°C until the material dissolved.

[0191] A mixture of 47.8 g of A1 polyester (ethyl acetate solution), 93.1 g of A2 polyester, and 120.0 g of ethyl acetate was stirred at 95°C for 2 hours. After these 2 hours, 0.31 g of tert-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added. After stirring at 95°C for 10 minutes, a mixture of 62.1 g of methyl methacrylate and 62.1 g of butyl methacrylate mixed with 0.93 g of tert-butyl peroxy-2-ethylhexanoate was metered into the system at 95°C over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, 0.25 g of tert-butyl peroxy-2-ethylhexanoate was added twice, with an interval of 1 hour between additions, and the mixture was stirred at 95°C for a further 5 hours. Finally, the mixture was diluted with 100.0 g of ethyl acetate to adjust the viscosity.

[0192] Invention Example 6

[0193] In a pressure vessel with a thermostat, blade stirrer and internal thermometer connected, 31.5 g of TAFMERDF 640 and 51.3 g of ENGAGE 7447 were added as initial charge to 100.0 g of ethyl acetate and 48.0 g of cyclohexane (CH) and stirred at 98° C. until the material was dissolved. A mixture of 47.8 g of A1 type polyester (ethyl acetate solution) and 93.1 g of A2 type polyester and 120.0 g of ethyl acetate was stirred at 98° C. for 2 hours. After these 2 hours, 0.31 g of tert-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added.

[0194] After stirring at 98°C for 10 minutes, a mixture of 62.1 g of methyl methacrylate and 62.1 g of butyl methacrylate mixed with 0.93 g of tert-butyl peroxy-2-ethylhexanoate was metered into the system at 98°C over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, another 0.25 g of tert-butyl peroxy-2-ethylhexanoate was added twice, with an interval of 1 hour between additions, and the mixture was stirred at 98°C for an additional 5 hours. Finally, the mixture was diluted with 100.0 g of ethyl acetate to adjust the viscosity.

[0195] Invention Example 7

[0196] In a pressure vessel equipped with a thermostat, blade stirrer, and internal thermometer, 31.5 g of ENGAGEHM 7387 and 51.3 g of ENGAGE 7447 were initially charged to 100.0 g of ethyl acetate and 48.0 g of cyclohexane (CH2) and stirred at 85°C until the materials dissolved. A mixture of 47.8 g of polyester type A1 (in ethyl acetate) and 93.1 g of polyester type A2 and 120.0 g of ethyl acetate was stirred at 85°C for 2 hours. After these 2 hours, 0.31 g of tert-butyl peroxy-2-ethylhexanoate and 5.0 g of ethyl acetate were added. After stirring at 85°C for 10 minutes, a mixture of 62.1 g of methyl methacrylate and 62.1 g of butyl methacrylate, mixed with 0.93 g of tert-butyl peroxy-2-ethylhexanoate, was metered into the system at 85°C over a period of 1.5 hours via a metering pump. After the addition was complete and 30 minutes later, 0.25 g of tert-butyl peroxy-2-ethylhexanoate was added twice with an interval of 1 hour between additions, and the mixture was stirred for a further 5 h at 85° C. Finally, the mixture was diluted with 100.0 g of ethyl acetate for viscosity adjustment.

[0197] Experimental results

[0198] Some properties of the adhesives obtained in Inventive Examples 1 to 7 can be found in Table 2 below.

[0199] Table 2: Properties of adhesives

[0200] Example SC[%] Dynamic viscosity [mPas] Residual monomers [%] Appearance 1 46.1 2800 1.3 White, scattered 2 46.5 1600 1.1 White, scattered 3 45.9 2900 0.8 White, scattered 4 45.8 3000 0.8 White, scattered 5 46.1 1300 1.1 White, scattered 6 47.1 1800 1.1 White, scattered 7 44.7 2100 1.1 White, scattered

[0201] SC: solid content in wt%

[0202] Dynamic viscosity: Dynamic viscosity in mPas

[0203] Residual monomers: residual monomer content in wt%

[0204] All of the inventive examples exhibited solids-to-viscosity ratios that ensured user processability and met the requirements for achieving the highest possible solids content.

[0205] Laboratory Applications of Heat Seal Coating Systems

[0206] The heat seal coating systems obtained in Examples 1 to 7 were applied to the respective These systems were tested on PET and AlPET foils, whereby dry layers with a thickness of 4 to 7 μm were obtained.

[0207] Laboratory drying of coated foil

[0208] After a short air drying period (5 to 10 minutes), the foil was dried in a convection oven at 80 to 100° C. for 15 seconds.

[0209] Determination of heat seals and sealed seam strength

[0210] The sealing process was carried out using heat sealing equipment from Brugger (HSG / ET).

[0211] Sealing conditions:

[0212] Temperature: 180°C

[0213] Pressure: 0.3MPa

[0214] Time: 0.5 seconds

[0215] Sealing area: 100×10mm

[0216] The seal seam strength was determined by cutting the sample into strips with a width of 15 mm and stretching the strips at a speed of 100 mm / min using a tensile testing machine from ZwickRoell, model zwickiLine Z0.5TN materials testing machine (with Xforce HP force sensor box, nominal force 100 N). Note that during the peel test, the angle between the separated foil part and the remaining part that has not been stressed is 90° and an additional 180°.

[0217] The results are given in Tables 3 and 4 below.

[0218] Table 3: Heat sealing performance

[0219]

[0220] Table 4: Heat-sealed seam strength of Inventive Example 6 sealed under different sealing conditions

[0221]

Claims

1. A heat-sealable coating system suitable for sealing various types of substrates, comprising a film-forming dispersion comprising: As the polyester or polyester mixture of type A polymer, Poly(meth)acrylate as type B polymer, As a graft copolymer of type A polymer and type B polymer of AB type polymer, a polyolefin or polyolefin mixture as a polymer of type C, and A graft copolymer as a CD type polymer, which is composed of a C type polymer and a poly(meth)acrylate as a D type polymer, It is characterized by: The dispersion comprises 30 to 60 wt% of ethyl acetate, based on the total weight of the dispersion, and wherein the dispersion comprises 20% to 50% by weight of polymer type A, 10 to 20% by weight of polymer type B, 10 to 20% by weight of AB type polymer, 5 to 25 wt% of a polymer of type C, and 15 to 35 wt.% of a CD type polymer, In each case, this is based on the total mass of polymer types A, B, C, AB and CD.

2. The coating system according to claim 1, characterized in that The dispersion contains 50 to 55 weight percent ethyl acetate.

3. The coating system according to claim 1 or 2, characterized in that The dispersion comprises 0.5% to 10% by weight, preferably 5% to 7.5% by weight, of cyclohexane.

4. The coating system according to any one of claims 1 to 3, characterized in that The dispersion comprises 25 to 40 wt. % of polymer type A, 10% to 15% by weight of polymer type B, 10 to 20% by weight of AB type polymer, 10 to 15 wt% of a polymer of type C, and 20 to 30 wt.% of a CD type polymer, In each case, this is based on the total mass of polymer types A, B, C, AB and CD.

5. The coating system according to any one of claims 1 to 4, It is characterized by: The proportion of the C-type polymer, including the proportion of the C-type polymer in the CD-type polymer, is 5 to 40% by weight, preferably 10 to 20% by weight, based on the total mass of the A-type, B-type, C-type, AB-type and CD-type polymers.

6. The coating system according to any one of claims 1 to 5, It is characterized by: From 1% to 15%, preferably from 2.5% to 9%, of the carbons in the backbone of the C-type polymer are tertiary carbon atoms.

7. The coating system according to any one of claims 1 to 6, characterized in that The A-type polymer is a mixture of two polyesters, and the C-type polymer is a mixture of two polyolefins.

8. The coating system according to any one of claims 1 to 7, characterized in that The AB type polymer is a graft copolymer having a polyester backbone and poly(meth)acrylate side chains.

9. The coating system according to any one of claims 1 to 8, characterized in that Type C polymers are EPM, hydrogenated polybutadiene, or copolymers of ethylene and α-olefins having 4 to 12, preferably 4 to 6, carbon atoms.

10. The coating system according to any one of claims 1 to 9, characterized in that The polymer of type C comprises ethylene repeating units in a proportion of 60% to 90% by weight, preferably >70% to 85% by weight, and has a weight average molecular weight M w It ranges from 10,000 to 250,000.

11. The coating system according to any one of claims 1 to 10, characterized in that To prepare graft copolymers AB and CD, grafting of type B polymer onto type A polymer and grafting of type D polymer onto type C polymer are carried out simultaneously, and type B polymer and type D polymer preferably have the same composition.

12. The coating system according to any one of claims 1 to 11, characterized in that Its dynamic viscosity is 200 mPas to 10,000 mPas, preferably 500 mPas to 5,000 mPas, more preferably 1,000 mPas to 4,000 mPas, as determined by the method given in the description.

13. A method for sealing various types of substrates, characterized in that The foil is coated with the coating system according to any one of claims 1 to 12, the coating is dried at a temperature below 100° C., preferably at a temperature of 80° C. to 98° C., and the coated side of the foil is placed on the material to be sealed and sealed at a temperature of 120° C. to 220° C. and a pressure of 0.2 MPa to 0.6 MPa within a time period of 0.1 second to 1 second.

14. The method according to claim 13, characterized in that The foil in contact with the coating system and the material to be sealed are made of the same kind of polymer, preferably polyethylene terephthalate.

15. The method according to claim 13, characterized in that Aluminum foil, polyester foil, PET foil or PET-coated foil is used as foil, and a substrate made of polystyrene, polyester, PET or polyvinyl chloride is used as the material to be sealed.

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