CA2200890A1 - Use of aqueous dispersion as heat-sealing lacquer - Google Patents
Use of aqueous dispersion as heat-sealing lacquerInfo
- Publication number
- CA2200890A1 CA2200890A1 CA002200890A CA2200890A CA2200890A1 CA 2200890 A1 CA2200890 A1 CA 2200890A1 CA 002200890 A CA002200890 A CA 002200890A CA 2200890 A CA2200890 A CA 2200890A CA 2200890 A1 CA2200890 A1 CA 2200890A1
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- Canada
- Prior art keywords
- weight
- polymer
- ethylene
- ethylenically unsaturated
- monomers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- 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
- C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
- C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
- C09J123/04—Homopolymers or copolymers of ethene
- C09J123/08—Copolymers of ethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/12—Polymerisation in non-solvents
- C08F2/16—Aqueous medium
- C08F2/22—Emulsion polymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
- C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts 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
- C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
- C09J151/06—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/54—Aqueous solutions or dispersions
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
- C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
- C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
Abstract
A method for heat-sealing substrates is described, which comprises coating a substrate with an aqueous dispersion comprising an ethylene polymer A), with at least 20 % by weight of ethylene and at least 5 % by weight of an ethylenically unsaturated acid, and a free-radically polymerized polymer B), and pressing the coated substrate with a second substrate at elevated temperature.
Description
220~890 Use of aqueous dispersions as heat-sealing lacquer The present invention relates to a method of heat-sealing 5 substrates.
Packaging i8 widely prepared by subjecting substrates to heat sealing, with at least one of the two substrates to be joined being coated with a meltable polymer, referred to as a sealing 10 lacquer.
The substrates are joined under temperature and pressure conditions which do not deform or damage the substrates themselves but under which the polymer coating melts and bonds 15 with the other substrate. After cooling, the substrates are connected with one another in the region of the heated areas.
occasionally, only part of the area of one substrate that has been coated with the meltable polymer is sealed with the other 20 substrate in dotwise or linear zones. Por example, an aluminum foil coated with 8 heat-sealing lacquer is sealed as a lid on the edge of the container made from thermoformed plastic film.
The literature recommends numerous meltable polymers as 25 heat-sealing lacquers.
In selecting them, a variety of criteria have a role to play;
these include the distance between their melting point and the melting temperature of the substrates, adhesion to the 30 substrates, the strength of the sealed seam, and the coating conditions under which the heat-sealing lacquer is applied to one of the substrates, and these requirements must be satisfied for widely differing substrates. In the case of food and drug packaging, moreover, it i8 also necessary to ensure compliance 35 with foodstuffs law and pharmacological harmlessness, respectively.
Since coating of the substrate and bonding are conducted in different operations, the requirements to which heat-sealing 40 coatings are subject are sometimes contradictory.
The coated substrates must be able to be stacked without sticking together (blocking resistance).
In the course of heat sealing, however, it is desirable not to have to use excessive temperatures, and the bonds obtained are required to show high strength (good heat-sealability).
5 DE-A 39 21 256 discloses heat-sealing lacquers based on an aqueous dispersion which comprises two different free-radically polymerized polymers.
The heat-sealing lacquers of US-A-5 385 967 also include two 10 different polymers, the difference in their glass transition temperatures being at least 20~C.
EP-A-129 178 relates to heat-sealable coating compositions in an organic solvent. The coating composition consists of 3 polymeric 15 constituents, including, for example, a polyolefin, a polyacrylate and a copolymer.
The heat-sealing lacquers known to date do not adequate fulfil the requirements set out above.
It is an object of the present invention to provide a method of heat-sealing substrates using an aqueous heat-sealing lacquer, while meeting the requirements set out above. In particular, the method is intended to provide for good sealed-seam strength even 25 where the substrates to be heat-sealed are aluminum and polymers.
We have found that this object is achieved by a method of heat-sealing substrates, which comprises coating a substrate with an aqueous dispersion comprising an ethylene polymer A), with at 30 least 20 % by weight of ethylene and at least 5 % by weight of an ethylenically unsaturated acid, and a free-radically polymerized polymer B) and pressing the coated substrate with a second substrate at elevated temperature. We have also found aqueous dispersions suitable for this method.
The aqueous dispersions for the novel method include an ethylene polymer A) and a free-radically polymerized polymer B).
The ethylene polymer comprises at least 20 % by weight, preferably 40 at least 40 % by weight and, with particular preference, at least 60 % by weight of ethylene and at least 5 % by weight, preferably at least 10 % by weight and, with particular preference, at least 15 % by weight of an ethylenically unsaturated acid as its structural components.
The ethylene polymer A) consists in particular of a1) from 20 to 95 % by weight, preferably from 40 to 90 % by weight and, with particular preference, from 60 to 85 % by weight of ethylene, 5 a2) from 5 to 80 % by weight, preferably from 10 to 60 % by weight and, with particular preference, from 15 to 40 % by weight of an ethylenically unsaturated acid, and a3) from 0 to 60 % by weight, preferably from 0 to 40 % by weight and, with particular preference, from 0 to 20 % by weight of further monomers that are different from a) and b).
Ethylenically unsaturated acids a2) are, in particular, acrylic or methacrylic acid.
Possible examples of further monomers a3) which can be copolymerized with ethylene are (meth)acrylates, especially Cl-C10 (meth)acrylates, such as methyl, ethyl, propyl, butyl or ethoxylhexyl (meth)acrylate, (meth)acrylonitrile, 20 (meth)acrylamide or vinyl esters, such as vinyl acetate or vinyl propionate.
The preparation techniques for the ethylene polymers A are familiar to the skilled worker. Polymers of this kind are 25 prepared, for example, by (co)polymerizing ethylene in continuously operated tubular polymerization systems under pressures of 500-5000 bar and at 50-450~C in the presence of polymerization initiators which break down with formation of free radicals.
The densities of such copolymers are generally greater th'an 0.925 g/cm3 (T - 23~C). Their molecular weights are generally about 500-40,000 daltons, especially 5000-20,000 (Mn)~ Following polymerization, the copolymers A used in accordance with the 35 invention are converted to an aqueous emulsion preferably by pressure emulsification, with or without the addition of a neutralizing agent.
This technique of pressure emulsification of polyethylene to form 40 aqueous (secondary) emulsions is familiar to the skilled worker.
Suitable neutralizing agents are preferably ammonia, diethylamine, dimethylethanolamine, diethanolamine, etc.
To prepare the emulsion it is also possible to use customary ionic and/or nonionic emulsifiers. Preference is given to highly mobile, fine and light-colored emulsions of the polymer A with a solids content of about 20-40 % and a pH of more than 8.
The polymer B) consists in particular of bl) from 30 to 100 % by weight of monomers referred to as principal monomers, selected from Cl-C20 alkyl (meth)acrylates, C8-Cl2 vinyl aromatic compounds, vinyl esters of carboxylic acids of 1 to 20 carbons, and ethylenically unsaturated nitriles, ~5 b2) from 0 to 30 ~ by weight of an ethylenically unsaturated acid or anhydride, b3) from 0 to 20 % by weight of ethylenically unsaturated compounds having a crosslinking action, and b4) from 0 to 70 % by weight of further monomers that are different from bl)-b3).
Preferably, the polymer B) consists of from 60 to 100 % by weight, 25 particularly preferably from 80 to 100 % by weight, of the monomers b1), from 0 to 10 % by weight, particularly preferably from 0 to 4 % by weight, of the monomers b2), from 0 to 10 % by weight, particularly preferably from 0 to 5 % by weight, of the monomers b3), and from 0 to 40 % by weight and , with particular 30 preference, from 0 to 20 % by weight of the monomers b4).
As monomers bl) mention may be made in particular of methyl, ethyl, propyl, n-butyl and 2-ethylhexyl (meth)acrylate, vinyl-aromatic compounds such as vinyltoluene, o and p-styrene 35 and preferably styrene, and vinyl laurate, stearate, propionate and acetate.
The alkyl (meth)acrylates and the vinyl aromatic compounds, and mixtures thereof, are particularly suitable.
Monomers b2) are, in particular, C3-C5 mono or dicarboxylic acids and/or their anhydrides.
Monomers b2) are commonly employed in minor amounts, preferably in 45 amounts of less than 4 % by weight based on ~), and, with particular preference, monomers b2) are absent from B).
-Examples of monomers b3), which have a crosslinking action (and are therefore referred to below simply as crosslinkinq monomers) are free-radically polymerizable monomers having at least one epoxy, hydroxyl, N-alkylol, N-alkoxy or amidine group or at least 5 two nonconjugated ethylenically unsaturated double bonds. A
combination of such compounds is of course possible.
Examples of epoxy-functional monomers are glycidyl acrylate, glycidyl methacrylate and vinyl glycidyl ether.
Preferred N-alkylol compounds are the N-alkylolamides of ethylenically unsaturated carboxylic acids with 1 to 4 carbons in the alkyl, such as N-methylolacrylamide, N-ethanolacrylamide, N-propanolacrylamide, N-methylolmethacrylamide, 15 N-ethanolmethacrylamide, N-methylolmaleimide, N-methylolmaleamide and N-methylolvinylbenzamide.
Suitable N-alkoxymethyl acrylates and methacrylates are primarily compounds with 1 to 8 carbons in the alkoxy, such as 20 N-(methoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-(methoxymethyl)methacrylamide and N-(butoxymethyl)methacrylamide, and methylolallyl carbamates whose methylols can be etherified by Cl-C8 alkyl.
Carbonyl-cont~ini ng monomers are preferably acrolein, 25 diacetonacrylamide, formylstyrene, vinyl alkyl ketones and (meth)acryloxyalkylpropanals as set forth in EP 0 003 516, diacetone acrylate, acetonyl acrylate, diacetone methacrylate, 2-hydroxypropyl acrylate acetylacetate and 1,4-butanediol acrylate acetylacetate.
A monomer which contains aziridine groups that may be me~tioned is 2~ aziridinyl)ethyl methacrylate.
As crosslinking components having at least two acrylic, 35 methacrylic, alkyl or vinyl groups, or appropriate combinations, mention may be made of alkylene glycol di(meth)acrylates, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, propylene glycol diacrylate and triethylene glycol dimethacrylate, 1,3-glycerol dimethacrylate, 40 l,l,l-trimethylolpropane dimethacrylate, l,l,l-trimethylolethane diacrylate, pentaerythritol trimethacrylate, sorbitol pentamethacrylate, methylenebisacrylamide and -methacrylamide, divinylbenzene, vinyl methacrylate, vinyl crotonate, vinylacrylate and divinyl adipate, diallyl phthalate, allyl 45 methacrylate, allyl acrylate, diallyl maleate, diallyl itaconate, diallyl malonate, diallyl carbonate, triallyl citrate, divinyl - ' 220Q890 ether, ethylene glycol divinyl ether and cyclopentadienyl (meth)acrylate.
In addition to the use of such crosslinking monomers, the 5 internal strength of the polymer films can under certain circumstances be increased by adding metal salts, such as salts of Ca, Mg and Zn, after polymerization has taken place, provided they include groups capable of bonding with the salts, such as, for example, carboxyl groups; it is also possible to add 10 hydrazine derivatives, aminooxyalkanes, and condensation products based on formaldehyde, melamine, phenol and/or urea, after polymerization has taken place.
Examples of further monomers b4) are vinyl halides, preferably 15 vinyl chloride and vinylidene chloride, nonaromatic Cz-C8 hydrocarbons with one or two olefinic double bonds, such as butadiene, isoprene or chloroprene, esters of acrylic and methacrylic acid with alcohols of 1 to 20 carbons which include at least one heteroatom not counting the oxygen in the alcohol 20 group, and/or include an aliphatic or aromatic ring, such as 2-ethoxyethyl acrylate, 2-butoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, aryl, alkaryl or cycloalkyl (meth)acrylates such as cyclohexyl ~meth)acrylate, phenylethyl (meth)acrylate and 25 phenylpropyl (meth)acrylate, or acrylic esters of heterocyclic alcohols, such as furfuryl (meth)acrylate.
Examples of other possible monomers b4) are (meth)acrylamide, N-Cl-C4 alkyl derivatives, and hydroxy-functional comonomers such 30 as Cl-C15 alkyl (meth)acrylates substituted by one or two hydroxyls. Particularly important hydroxy-functional comohomers are Cl-C8 hydroxyalkyl (meth)acrylates, such as n-hydroxyethyl, n-hydroxypropyl and n-hydroxybutyl (meth)acrylate.
35 Particularly preferred polymers B) comprise no chlorine-containing compounds such as vinyl chloride and vinylidene chloride.
In addition, the polymers B) include ethylene preferably in - at 40 best - minor amounts of, in particular, less than 20 % by weight, particularly preferably less than 10 % by weight and, with very particular preference, less than 5 % by weight. In particular, there is no ethylene in B).
The polymer ~) preferably has a glass transition temperature (calculated in accordance with Fox) of from -20 to +130, preferably from 0 to +90, particularly preferably from +10 to +70~C.
The glass transition temperature (Tg) can be calculated by the method of Fox (T.G. Fox, Bull. Am. Phys. Soc. (Ser. II) 1, [1956]
123), according to which the Tg of copolymers is given in good approximation by Xl x2 xn + ....... +
Tg Tg1 Tg2 Tgn where X1, x2 ... xn = mass fractions of the monomers 1, 2, ... n and Tg1, Tg2 ... Tgn = glass transition temperatures of the monomers 1, 2 ... n in kelvins.
20 Tg is known for major monomers and is given, for example, in ~J. Brandrup, E.H. Immergut, Polymer Handbook, 1st Ed., J. Wiley & Sons, New York 1966".
Polymer B) i8 prepared by free-radical polymerization.
25 Appropriate polymerization techniques, such as polymerization in bulk, solution, suspension or emulsion, are known to the skilled worker.
The copolymers are prepared in particular by solution 30 polymerization with subsequent dispersion in water ~seco~dary dispersion) or, preferably, by emulsion polymerization.
In the course of the emulsion polymerization, the monomers are -as is usual - polymerized in the presence of a water-soluble 35 initiator and an emulsifier at (preferably) from 30 to 95~C.
Suitable free-radical polymerization initiators are all those capable of triggering a free-radical aqueous emulsion polymerization. They may be peroxides, for example alkali metal 40 peroxodisulfates, dibenzoyl peroxide, butyl perpivalate, t-butyl per-2-ethylhexanoate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and cumene hydroperoxide, or azo compounds, for example azobisisobutyronitrile or 2,2~-azobis(2-amidinopropane) dihydrochloride.
Suitability extends to combined systems composed of at least one organic reducing agent and at least one peroxide and/or hydroperoxide, for example tert-butyl hydroperoxide and sodium hydroxymethanesulfinate, or hydrogen peroxide and ascorbic acid.
5 Also suitable are combined systems which additionally include a small amount of a metal compound which is soluble in the polymerization medium and whose metallic component can exist in two or more valency states, for example ascorbic acid/iron(II) sulfate/hydrogen peroxide, where the ascorbic acid is frequently 10 replaced by sodium hydroxymethanesulfinate, sodium sulfite, sodium hydrogen sulfite or sodium metabisulfite, and the hydrogen peroxide by tert-butyl hydroperoxide or alkali metal peroxodisulfates and/or ammonium peroxodisulfates.
15 In general, the amount of free-radical initiator employed, based on the overall amount of monomers to be polymerized, is from 0.1 to 3 % by weight. With particular preference, ammonium and/or alkali metal peroxodisulfates or tert-butyl hydroperoxide in combination with a reducing agent are employed as initiator.
The manner by which the free-radical initiator system is added to the polymerization vessel in the course of the novel free-radical aqueous polymerization i8 familiar to the skilled worker. The system can be included in its entirety in the initial charge to 25 the polymerization vessel, or else introduced continuously or in portions in accordance with the rate of its consumption during the free-radical aqueous emulsion polymerization. In each individual case this will depend, as known to the skilled worker, both on the chemical nature of the initiator system and on the 30 temperature of polymerization. Preferably, part is included in the initial charge and the remainder is supplied to the polymerization zone in accordance with the rate of its consumption.
35 For the emulsion polymerization it is possible to use commonly known ionic and/or nonionic emulsifiers and/or protective colloids and stabilizers.
Suitable such surface-active substances are, in principle, the 40 emulsifiers and protective colloids commonly used as dispersants.
A detailed treatment of suitable protective colloids is given in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/I, makromolekulare Stoffe [macromolecular substances], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 411 - 420. Suitable 45 emulsifiers include anionic, cationic and nonionic types. As surface-active substances, preference is given to the exclusive used of emulsifiers, whose relative molecular weights - unlike those of the protective colloids - are usually below 1000. Where mixtures of surface-active substances are used, the individual components must of course be compatible with one another, and in case of doubt this can be checked by means of a few preliminary 5 experiments.
Preference is given to anionic and nonionic emulsifiers as surface-active substances. Common co ~ lsifiers are, for example, ethoxylated fatty alcohols ~E0 units: 3 to 50, CB-10 C36-alkyl), ethoxylated mono, di- and trialkylphenols (E0 units:
up to 50, C4-Cg-alkyl), alkali metal salts of dialkyl esters of sulfosuccinic acid, and alkali metal and ammonium salt~ of C8-C12-alkyl sulfates, of ethoxylated Cl2-C18-alkanol, (E0 units: 4 to 30), of ethoxylated alkylphenols (E0 units: 3 to 50, 15 C4-C9-alkyl), of C12-C18-alkylsulfonic acids and of alkylarylsulfonic acids (Cg-Cl8-alkyl).
Further suitable dispersants are compounds of the formula II
where R5 and R6 are hydrogen or C4-C14-alkyl and are not both 30 hydrogen, and X and Y can be alkali metal ions and/or ammonium ions. R5 and R6 are preferably linear or branched C6-C18-alkyl, especially with 6, 12 or 16 carbons, or are hydrogen but not both at the same time. X and Y are preferably sodium, potassium or ammonium ions, the former being particularly preferred.
35 Particularly advantageous compounds II are those in which X and Y
are sodium, R5 is branched C12-alkyl and R6 iB hydrogen or is R5.
Use is frequently made of industrial mixtures contA;ning from 50 to 90 ~ by weight of the monoalkylated product, such as Dowfax~ 2Al (trademark of Dow Chemical Company).
Further suitable emulsifiers are given in Houben-Weyl, Methoden der organischen Chemie, Band XIV/l, Makromolekulare Stoffe, Georg Thieme-Verlag, Stuttgart, 1961, (loc. cit) pp. 192 - 208.
45 To adjust the molecular weight it is possible to use regulators in the polymerization. Examples of suitable compounds are those containing -SH, such as mercaptoethanol, mercaptopropanol, ' 22~0890 thiophenol, thioglycol, ethyl thioglycolate, methyl thioglycolate, tert-dodecyl mercaptan and mercaptoacetic acid.
The aqueous dispersion used in the novel method can be obtained, 5 simply, by mixing the aqueous dispersion of the ethylene polymer A) with the aqueous dispersion of the polymer B).
However, it has proven particularly appropriate first to prepare a dispersion of the ethylene polymer A) as described above and 10 then to polymerize the monomers of the polymer B) in the presence of the ethylene polymer A). The monomers of B) can be included entirely in an initial charge or can be metered continuously into an initial charge cont~ining A). It is also possible, for example, for both A) or portions of A) and the monomers of B) to 15 be metered continuously over identical or different periods into an initial charge.
Since the content of acid groups and/or the corresponding salt groups in the ethylene polymer A) endows it with an emulsifying 20 effect, it is possible when following the above procedure for preparing B) in the presence of A) to do away with some of all of the emulsifier. If desired, it is possible to use, for example, from 0.05 to 3 % by weight of emulsifier, based on the total weight of A) plus B).
The resultant aqueous dispersion of A) and B) preferably has a solids content of from 20 to 70 % by weight.
The aqueous dispersion is used for sealable coatings, ie. as a 30 sealing lacquer, and may include additives customary for such use, examples being wetting agents, thickeners, antifoam~ and film formers.
For this use, the dispersion can first of all be applied to a 35 substrate, for example aluminum, printed or plain paper, cardboard packaging, or films of polyvinyl chloride, polyethylene terephthalate, polystyrene or polyolefins. The amount applied ~based on solids) is generally from 1 to 100 g, preferably from 10 to 15 g, per m2 of coated area.
The coated substrate is then pressed with a further, preferably uncoated substrate (sealing or heat-sealing). Examples of suitable uncoated substrates are, again, those indicated above.
Further candidate substrates are glass, metals and textiles.
11 220~8qO
With preference, at least one of the two substrates to be heat-sealed is made from plastic. With particularly preference, the substrate coated with a dispersion is made from aluminum. The plastic i8 eBpecially polystyrene, polyethylene terephtalate, 5 PVC, polyethylene or polypropylene.
~y means of heat-sealing it i8 possible to package articles, for example by coating an aluminum film with the heat-sealing lacquer in the form of dots or zones, and subsequently pressing this lO coated foil with, for example, a thermoformed plastic film so as to enclose an item to be packaged.
In the course of heat sealing, the substrates are pressed together by sealing jaws, which can be at 80-250~C. In the course 15 of this pressing operation, the pressures are generally from 0.1 to lO bar, in particular from 2 to 6 bar, with a pressing time (contact time) of at least 0.5 second, generally from 1 to 5 seconds.
20 The novel dispersions are notable for the fact that they bring about a seal of high sealed-seam strength, in particular between aluminum foil and polystyrene, polyethylene terephthalate, polyvinyl chloride and polyolefinic substances, including in particular ~ubstances of polypropylene and polyethylene; at the 25 same time, the film of sealing lacquer on its own possesses good blocking resistance.
Another notable feature of the novel dispersions is that they possess good adhesion to aluminum foil without the need for any 30 further primer coat on the aluminum surface.
Comparison Examples Comparison Examples 1 and 2 in accordance with US 5 385 967:
Copolymer I:
The copolymers I are water-soluble copolymers prepared by bulk polymerization following the method of DE-A-3 225 876.
For this preparation, 60 parts by weight of styrene and 40 parts by weight of acrylic acid were metered continuously into a 1 1 pressure vessel with a downstream pressure tube of twice the capacity, with a pressure regulator. The system was heated to 45 310~. The pressure was kept at between 5 and 50 bar and once was 22û08~0 varied within this range by means of a periodic pressure regulation over the course of one minute.
The residence time was 11 minutes; the copolymer melt was 5 discharged quantitatively at the same rate at fresh monomer mixture was supplied. The copolymer had a mean molecular weight Mn of 650 and a polydispersity U = MW/Mn -1 of 1.5.
Preparation of the copolymers II in the presence of the 10 copolymers I:
The amounts of an aqueous solution of the copolymers I as indicated in Table 1 were charged to a 3 1 four-neck flask fitted with reflux condenser, 2 feed vessels, a thermometer, a pilot 15 stirrer and gas inlet and outlet, the reaction vessel was flushed with nitrogen, and the solution was heated to 85~C. 54 g of a 1.5 % strength aqueous sodium peroxodisulfate solution were added, and then 1000 g of the monomers of copolymer II were run in at 85~C with stirring over the course of 2 h. At the same time, 20 in a separate feed, 126 g of a 1.5 % strength sodium peroxodisulfate solution were added dropwise over the course of 2.5 h. After the end of the two feeds, reaction was continued at 85~C for 1 h and then the reaction mixture was cooled to room temperature.
The polymer dispersions obtained by this procedure were free from coagulum. Their composition is shown in Table 1.
Comparison Examples 3 and 4 correspond to Examples 1 and 2 of 30 DE--A--39 21 256:
Mixture 1 was charged together with 260 g of isobutanol to a reaction vessel, and the resulting mixture was heated to 105~C.
Then mixture 2 was added, and the batch was polymerized at reflux 35 for 2.5 hours. Subsequently, mixture 3 was metered in at about 105~C over the course of 3 hours.
The batch was then polymerized at 105~C for 4 hours, during which it was diluted with 200 g of isobutanol. After it had cooled to 40 60~C, 35.4 g of 25 % strength by weight aqueous ammonia solution and then 850 g of water were stirred in. An isobutanol/water mixture was distilled off under reduced pressure until virtually no more isobutanol passed over. During the distillation, an amount of water corresponding to the amount of liquid removed by 45 distillation was added.
2200~90 Mixture 1:
Comp. Example 3 Comp. Example 4 5 Methyl methacrylate (g) 160 145 n-Butyl acrylate (g) 100 110 Acrylic acid (g) 20 25 Mixture 2:
tert-Butyl benzoate ~g) 1.5 1.5 15 tert-Butyl peroctoate (g) 1.5 1.5 Isobutanol (g) 30 30 20 Mixture 3:
Methyl methacrylate (g) 370 380 n-Butyl methacrylate (g) 350 340 tert-Butyl (g) 7.5 6.7 25 perbenzoate tert-Butyl peroctoate (g) 4.5 6.0 Isobutanol (g) 150 140 The composition is given in Tab. 1.
Comparison Example 5 3S As Comparison Example 5, the product Plexisol~ PM 555 from Rohm, Darmstadt was tested. This product is currently state of the art in terms of sealability with respect to polypropylene. It is a methacrylate/olefin-based emulsion in butyl acetate/methyl ethyl ketone.
Products of thi~ type are described in EP 023 978 (to Rohm). To ensure bond strength to aluminum foil, Rohm recommends a primer of PVC copolymers (eg. Vinylite VMCH from Union Carbide).
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~, 0 ~ m ~ ~ n ~J O C~ 0 3 :~: CO o 0 O _ ~ 0 C
G L. O O - a ~ ~ r ,- X Z t ) ~ U C~ U
Glass transition temperatures of the copolymers The glass transition temperatures were determined by differential 5 canning calorimetry in accordance with ASTM 3418/82. They can also be calculated approximately, using the Fox equation, from the glass transition temperatures of the monomers (T.G. Fox, Bull. Am.
Phys. Soc. Ser. II 1, (1956) 123).
10 Table 2: Glas~ transition temperatures in ~C [DSC]
Example Copolymer ICopolymer II
Cl 125 -26 20 Examples Polymer B was prepared in the presence of polymer A. The composition of polymers is shown in Table 3.
25 To do this, ethylene polymer A was charged to a 3 1 reaction flask with reflux condenser, 3 feed vessels, thermometer, pilot stirrer and nitrogen inlet. Together with 90 % by weight of the total amount of initiator system used (tert-butyl hydroperoxide, Na hydroxymethylsulfinate) and after nitrogen flushing, this 30 solution was heated to 70~C with stirring.
Subsequently, the monomers and the remaining amounts of initiator (0.8 % by weight t-BHP and 0.8 % by weight Na hydroxymethylsulfinate, based on monomers of copolymer B) were 35 added continuously with stirring over the course of 1.5 h. In Examples 1 to 10, the monomers were metered in in the sequence indicated in Table 3.
The batch was subsequently stirred at 70~C for one hour more and 40 then cooled to room temperature, to give coagulum-free dispersions whose composition and characteristic data are summarized in Table 3.
To give coagulum-free dispersions whose composition and 45 characteristic data are summarized in Table 3.
' ' 2200890 Table 3: Composition of the copolymers from the Examples Composition Quantitative Tg (~C) ratio Copol. B
Copol. A:B
Ex. No. Copol. A/ SC
Copol. B (%) 1 A 60 E/20 EHA/20 AA; NH3 33.4:66.6 13.6 34.1 B 50 nBA/50 S
2 A 60 E/20 EHA/20 AA NH3 33.4:66.6 63.2 34.4 B 20 nBA/80 S
Packaging i8 widely prepared by subjecting substrates to heat sealing, with at least one of the two substrates to be joined being coated with a meltable polymer, referred to as a sealing 10 lacquer.
The substrates are joined under temperature and pressure conditions which do not deform or damage the substrates themselves but under which the polymer coating melts and bonds 15 with the other substrate. After cooling, the substrates are connected with one another in the region of the heated areas.
occasionally, only part of the area of one substrate that has been coated with the meltable polymer is sealed with the other 20 substrate in dotwise or linear zones. Por example, an aluminum foil coated with 8 heat-sealing lacquer is sealed as a lid on the edge of the container made from thermoformed plastic film.
The literature recommends numerous meltable polymers as 25 heat-sealing lacquers.
In selecting them, a variety of criteria have a role to play;
these include the distance between their melting point and the melting temperature of the substrates, adhesion to the 30 substrates, the strength of the sealed seam, and the coating conditions under which the heat-sealing lacquer is applied to one of the substrates, and these requirements must be satisfied for widely differing substrates. In the case of food and drug packaging, moreover, it i8 also necessary to ensure compliance 35 with foodstuffs law and pharmacological harmlessness, respectively.
Since coating of the substrate and bonding are conducted in different operations, the requirements to which heat-sealing 40 coatings are subject are sometimes contradictory.
The coated substrates must be able to be stacked without sticking together (blocking resistance).
In the course of heat sealing, however, it is desirable not to have to use excessive temperatures, and the bonds obtained are required to show high strength (good heat-sealability).
5 DE-A 39 21 256 discloses heat-sealing lacquers based on an aqueous dispersion which comprises two different free-radically polymerized polymers.
The heat-sealing lacquers of US-A-5 385 967 also include two 10 different polymers, the difference in their glass transition temperatures being at least 20~C.
EP-A-129 178 relates to heat-sealable coating compositions in an organic solvent. The coating composition consists of 3 polymeric 15 constituents, including, for example, a polyolefin, a polyacrylate and a copolymer.
The heat-sealing lacquers known to date do not adequate fulfil the requirements set out above.
It is an object of the present invention to provide a method of heat-sealing substrates using an aqueous heat-sealing lacquer, while meeting the requirements set out above. In particular, the method is intended to provide for good sealed-seam strength even 25 where the substrates to be heat-sealed are aluminum and polymers.
We have found that this object is achieved by a method of heat-sealing substrates, which comprises coating a substrate with an aqueous dispersion comprising an ethylene polymer A), with at 30 least 20 % by weight of ethylene and at least 5 % by weight of an ethylenically unsaturated acid, and a free-radically polymerized polymer B) and pressing the coated substrate with a second substrate at elevated temperature. We have also found aqueous dispersions suitable for this method.
The aqueous dispersions for the novel method include an ethylene polymer A) and a free-radically polymerized polymer B).
The ethylene polymer comprises at least 20 % by weight, preferably 40 at least 40 % by weight and, with particular preference, at least 60 % by weight of ethylene and at least 5 % by weight, preferably at least 10 % by weight and, with particular preference, at least 15 % by weight of an ethylenically unsaturated acid as its structural components.
The ethylene polymer A) consists in particular of a1) from 20 to 95 % by weight, preferably from 40 to 90 % by weight and, with particular preference, from 60 to 85 % by weight of ethylene, 5 a2) from 5 to 80 % by weight, preferably from 10 to 60 % by weight and, with particular preference, from 15 to 40 % by weight of an ethylenically unsaturated acid, and a3) from 0 to 60 % by weight, preferably from 0 to 40 % by weight and, with particular preference, from 0 to 20 % by weight of further monomers that are different from a) and b).
Ethylenically unsaturated acids a2) are, in particular, acrylic or methacrylic acid.
Possible examples of further monomers a3) which can be copolymerized with ethylene are (meth)acrylates, especially Cl-C10 (meth)acrylates, such as methyl, ethyl, propyl, butyl or ethoxylhexyl (meth)acrylate, (meth)acrylonitrile, 20 (meth)acrylamide or vinyl esters, such as vinyl acetate or vinyl propionate.
The preparation techniques for the ethylene polymers A are familiar to the skilled worker. Polymers of this kind are 25 prepared, for example, by (co)polymerizing ethylene in continuously operated tubular polymerization systems under pressures of 500-5000 bar and at 50-450~C in the presence of polymerization initiators which break down with formation of free radicals.
The densities of such copolymers are generally greater th'an 0.925 g/cm3 (T - 23~C). Their molecular weights are generally about 500-40,000 daltons, especially 5000-20,000 (Mn)~ Following polymerization, the copolymers A used in accordance with the 35 invention are converted to an aqueous emulsion preferably by pressure emulsification, with or without the addition of a neutralizing agent.
This technique of pressure emulsification of polyethylene to form 40 aqueous (secondary) emulsions is familiar to the skilled worker.
Suitable neutralizing agents are preferably ammonia, diethylamine, dimethylethanolamine, diethanolamine, etc.
To prepare the emulsion it is also possible to use customary ionic and/or nonionic emulsifiers. Preference is given to highly mobile, fine and light-colored emulsions of the polymer A with a solids content of about 20-40 % and a pH of more than 8.
The polymer B) consists in particular of bl) from 30 to 100 % by weight of monomers referred to as principal monomers, selected from Cl-C20 alkyl (meth)acrylates, C8-Cl2 vinyl aromatic compounds, vinyl esters of carboxylic acids of 1 to 20 carbons, and ethylenically unsaturated nitriles, ~5 b2) from 0 to 30 ~ by weight of an ethylenically unsaturated acid or anhydride, b3) from 0 to 20 % by weight of ethylenically unsaturated compounds having a crosslinking action, and b4) from 0 to 70 % by weight of further monomers that are different from bl)-b3).
Preferably, the polymer B) consists of from 60 to 100 % by weight, 25 particularly preferably from 80 to 100 % by weight, of the monomers b1), from 0 to 10 % by weight, particularly preferably from 0 to 4 % by weight, of the monomers b2), from 0 to 10 % by weight, particularly preferably from 0 to 5 % by weight, of the monomers b3), and from 0 to 40 % by weight and , with particular 30 preference, from 0 to 20 % by weight of the monomers b4).
As monomers bl) mention may be made in particular of methyl, ethyl, propyl, n-butyl and 2-ethylhexyl (meth)acrylate, vinyl-aromatic compounds such as vinyltoluene, o and p-styrene 35 and preferably styrene, and vinyl laurate, stearate, propionate and acetate.
The alkyl (meth)acrylates and the vinyl aromatic compounds, and mixtures thereof, are particularly suitable.
Monomers b2) are, in particular, C3-C5 mono or dicarboxylic acids and/or their anhydrides.
Monomers b2) are commonly employed in minor amounts, preferably in 45 amounts of less than 4 % by weight based on ~), and, with particular preference, monomers b2) are absent from B).
-Examples of monomers b3), which have a crosslinking action (and are therefore referred to below simply as crosslinkinq monomers) are free-radically polymerizable monomers having at least one epoxy, hydroxyl, N-alkylol, N-alkoxy or amidine group or at least 5 two nonconjugated ethylenically unsaturated double bonds. A
combination of such compounds is of course possible.
Examples of epoxy-functional monomers are glycidyl acrylate, glycidyl methacrylate and vinyl glycidyl ether.
Preferred N-alkylol compounds are the N-alkylolamides of ethylenically unsaturated carboxylic acids with 1 to 4 carbons in the alkyl, such as N-methylolacrylamide, N-ethanolacrylamide, N-propanolacrylamide, N-methylolmethacrylamide, 15 N-ethanolmethacrylamide, N-methylolmaleimide, N-methylolmaleamide and N-methylolvinylbenzamide.
Suitable N-alkoxymethyl acrylates and methacrylates are primarily compounds with 1 to 8 carbons in the alkoxy, such as 20 N-(methoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-(methoxymethyl)methacrylamide and N-(butoxymethyl)methacrylamide, and methylolallyl carbamates whose methylols can be etherified by Cl-C8 alkyl.
Carbonyl-cont~ini ng monomers are preferably acrolein, 25 diacetonacrylamide, formylstyrene, vinyl alkyl ketones and (meth)acryloxyalkylpropanals as set forth in EP 0 003 516, diacetone acrylate, acetonyl acrylate, diacetone methacrylate, 2-hydroxypropyl acrylate acetylacetate and 1,4-butanediol acrylate acetylacetate.
A monomer which contains aziridine groups that may be me~tioned is 2~ aziridinyl)ethyl methacrylate.
As crosslinking components having at least two acrylic, 35 methacrylic, alkyl or vinyl groups, or appropriate combinations, mention may be made of alkylene glycol di(meth)acrylates, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, propylene glycol diacrylate and triethylene glycol dimethacrylate, 1,3-glycerol dimethacrylate, 40 l,l,l-trimethylolpropane dimethacrylate, l,l,l-trimethylolethane diacrylate, pentaerythritol trimethacrylate, sorbitol pentamethacrylate, methylenebisacrylamide and -methacrylamide, divinylbenzene, vinyl methacrylate, vinyl crotonate, vinylacrylate and divinyl adipate, diallyl phthalate, allyl 45 methacrylate, allyl acrylate, diallyl maleate, diallyl itaconate, diallyl malonate, diallyl carbonate, triallyl citrate, divinyl - ' 220Q890 ether, ethylene glycol divinyl ether and cyclopentadienyl (meth)acrylate.
In addition to the use of such crosslinking monomers, the 5 internal strength of the polymer films can under certain circumstances be increased by adding metal salts, such as salts of Ca, Mg and Zn, after polymerization has taken place, provided they include groups capable of bonding with the salts, such as, for example, carboxyl groups; it is also possible to add 10 hydrazine derivatives, aminooxyalkanes, and condensation products based on formaldehyde, melamine, phenol and/or urea, after polymerization has taken place.
Examples of further monomers b4) are vinyl halides, preferably 15 vinyl chloride and vinylidene chloride, nonaromatic Cz-C8 hydrocarbons with one or two olefinic double bonds, such as butadiene, isoprene or chloroprene, esters of acrylic and methacrylic acid with alcohols of 1 to 20 carbons which include at least one heteroatom not counting the oxygen in the alcohol 20 group, and/or include an aliphatic or aromatic ring, such as 2-ethoxyethyl acrylate, 2-butoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, aryl, alkaryl or cycloalkyl (meth)acrylates such as cyclohexyl ~meth)acrylate, phenylethyl (meth)acrylate and 25 phenylpropyl (meth)acrylate, or acrylic esters of heterocyclic alcohols, such as furfuryl (meth)acrylate.
Examples of other possible monomers b4) are (meth)acrylamide, N-Cl-C4 alkyl derivatives, and hydroxy-functional comonomers such 30 as Cl-C15 alkyl (meth)acrylates substituted by one or two hydroxyls. Particularly important hydroxy-functional comohomers are Cl-C8 hydroxyalkyl (meth)acrylates, such as n-hydroxyethyl, n-hydroxypropyl and n-hydroxybutyl (meth)acrylate.
35 Particularly preferred polymers B) comprise no chlorine-containing compounds such as vinyl chloride and vinylidene chloride.
In addition, the polymers B) include ethylene preferably in - at 40 best - minor amounts of, in particular, less than 20 % by weight, particularly preferably less than 10 % by weight and, with very particular preference, less than 5 % by weight. In particular, there is no ethylene in B).
The polymer ~) preferably has a glass transition temperature (calculated in accordance with Fox) of from -20 to +130, preferably from 0 to +90, particularly preferably from +10 to +70~C.
The glass transition temperature (Tg) can be calculated by the method of Fox (T.G. Fox, Bull. Am. Phys. Soc. (Ser. II) 1, [1956]
123), according to which the Tg of copolymers is given in good approximation by Xl x2 xn + ....... +
Tg Tg1 Tg2 Tgn where X1, x2 ... xn = mass fractions of the monomers 1, 2, ... n and Tg1, Tg2 ... Tgn = glass transition temperatures of the monomers 1, 2 ... n in kelvins.
20 Tg is known for major monomers and is given, for example, in ~J. Brandrup, E.H. Immergut, Polymer Handbook, 1st Ed., J. Wiley & Sons, New York 1966".
Polymer B) i8 prepared by free-radical polymerization.
25 Appropriate polymerization techniques, such as polymerization in bulk, solution, suspension or emulsion, are known to the skilled worker.
The copolymers are prepared in particular by solution 30 polymerization with subsequent dispersion in water ~seco~dary dispersion) or, preferably, by emulsion polymerization.
In the course of the emulsion polymerization, the monomers are -as is usual - polymerized in the presence of a water-soluble 35 initiator and an emulsifier at (preferably) from 30 to 95~C.
Suitable free-radical polymerization initiators are all those capable of triggering a free-radical aqueous emulsion polymerization. They may be peroxides, for example alkali metal 40 peroxodisulfates, dibenzoyl peroxide, butyl perpivalate, t-butyl per-2-ethylhexanoate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and cumene hydroperoxide, or azo compounds, for example azobisisobutyronitrile or 2,2~-azobis(2-amidinopropane) dihydrochloride.
Suitability extends to combined systems composed of at least one organic reducing agent and at least one peroxide and/or hydroperoxide, for example tert-butyl hydroperoxide and sodium hydroxymethanesulfinate, or hydrogen peroxide and ascorbic acid.
5 Also suitable are combined systems which additionally include a small amount of a metal compound which is soluble in the polymerization medium and whose metallic component can exist in two or more valency states, for example ascorbic acid/iron(II) sulfate/hydrogen peroxide, where the ascorbic acid is frequently 10 replaced by sodium hydroxymethanesulfinate, sodium sulfite, sodium hydrogen sulfite or sodium metabisulfite, and the hydrogen peroxide by tert-butyl hydroperoxide or alkali metal peroxodisulfates and/or ammonium peroxodisulfates.
15 In general, the amount of free-radical initiator employed, based on the overall amount of monomers to be polymerized, is from 0.1 to 3 % by weight. With particular preference, ammonium and/or alkali metal peroxodisulfates or tert-butyl hydroperoxide in combination with a reducing agent are employed as initiator.
The manner by which the free-radical initiator system is added to the polymerization vessel in the course of the novel free-radical aqueous polymerization i8 familiar to the skilled worker. The system can be included in its entirety in the initial charge to 25 the polymerization vessel, or else introduced continuously or in portions in accordance with the rate of its consumption during the free-radical aqueous emulsion polymerization. In each individual case this will depend, as known to the skilled worker, both on the chemical nature of the initiator system and on the 30 temperature of polymerization. Preferably, part is included in the initial charge and the remainder is supplied to the polymerization zone in accordance with the rate of its consumption.
35 For the emulsion polymerization it is possible to use commonly known ionic and/or nonionic emulsifiers and/or protective colloids and stabilizers.
Suitable such surface-active substances are, in principle, the 40 emulsifiers and protective colloids commonly used as dispersants.
A detailed treatment of suitable protective colloids is given in Houben-Weyl, Methoden der organischen Chemie, Volume XIV/I, makromolekulare Stoffe [macromolecular substances], Georg-Thieme-Verlag, Stuttgart, 1961, pp. 411 - 420. Suitable 45 emulsifiers include anionic, cationic and nonionic types. As surface-active substances, preference is given to the exclusive used of emulsifiers, whose relative molecular weights - unlike those of the protective colloids - are usually below 1000. Where mixtures of surface-active substances are used, the individual components must of course be compatible with one another, and in case of doubt this can be checked by means of a few preliminary 5 experiments.
Preference is given to anionic and nonionic emulsifiers as surface-active substances. Common co ~ lsifiers are, for example, ethoxylated fatty alcohols ~E0 units: 3 to 50, CB-10 C36-alkyl), ethoxylated mono, di- and trialkylphenols (E0 units:
up to 50, C4-Cg-alkyl), alkali metal salts of dialkyl esters of sulfosuccinic acid, and alkali metal and ammonium salt~ of C8-C12-alkyl sulfates, of ethoxylated Cl2-C18-alkanol, (E0 units: 4 to 30), of ethoxylated alkylphenols (E0 units: 3 to 50, 15 C4-C9-alkyl), of C12-C18-alkylsulfonic acids and of alkylarylsulfonic acids (Cg-Cl8-alkyl).
Further suitable dispersants are compounds of the formula II
where R5 and R6 are hydrogen or C4-C14-alkyl and are not both 30 hydrogen, and X and Y can be alkali metal ions and/or ammonium ions. R5 and R6 are preferably linear or branched C6-C18-alkyl, especially with 6, 12 or 16 carbons, or are hydrogen but not both at the same time. X and Y are preferably sodium, potassium or ammonium ions, the former being particularly preferred.
35 Particularly advantageous compounds II are those in which X and Y
are sodium, R5 is branched C12-alkyl and R6 iB hydrogen or is R5.
Use is frequently made of industrial mixtures contA;ning from 50 to 90 ~ by weight of the monoalkylated product, such as Dowfax~ 2Al (trademark of Dow Chemical Company).
Further suitable emulsifiers are given in Houben-Weyl, Methoden der organischen Chemie, Band XIV/l, Makromolekulare Stoffe, Georg Thieme-Verlag, Stuttgart, 1961, (loc. cit) pp. 192 - 208.
45 To adjust the molecular weight it is possible to use regulators in the polymerization. Examples of suitable compounds are those containing -SH, such as mercaptoethanol, mercaptopropanol, ' 22~0890 thiophenol, thioglycol, ethyl thioglycolate, methyl thioglycolate, tert-dodecyl mercaptan and mercaptoacetic acid.
The aqueous dispersion used in the novel method can be obtained, 5 simply, by mixing the aqueous dispersion of the ethylene polymer A) with the aqueous dispersion of the polymer B).
However, it has proven particularly appropriate first to prepare a dispersion of the ethylene polymer A) as described above and 10 then to polymerize the monomers of the polymer B) in the presence of the ethylene polymer A). The monomers of B) can be included entirely in an initial charge or can be metered continuously into an initial charge cont~ining A). It is also possible, for example, for both A) or portions of A) and the monomers of B) to 15 be metered continuously over identical or different periods into an initial charge.
Since the content of acid groups and/or the corresponding salt groups in the ethylene polymer A) endows it with an emulsifying 20 effect, it is possible when following the above procedure for preparing B) in the presence of A) to do away with some of all of the emulsifier. If desired, it is possible to use, for example, from 0.05 to 3 % by weight of emulsifier, based on the total weight of A) plus B).
The resultant aqueous dispersion of A) and B) preferably has a solids content of from 20 to 70 % by weight.
The aqueous dispersion is used for sealable coatings, ie. as a 30 sealing lacquer, and may include additives customary for such use, examples being wetting agents, thickeners, antifoam~ and film formers.
For this use, the dispersion can first of all be applied to a 35 substrate, for example aluminum, printed or plain paper, cardboard packaging, or films of polyvinyl chloride, polyethylene terephthalate, polystyrene or polyolefins. The amount applied ~based on solids) is generally from 1 to 100 g, preferably from 10 to 15 g, per m2 of coated area.
The coated substrate is then pressed with a further, preferably uncoated substrate (sealing or heat-sealing). Examples of suitable uncoated substrates are, again, those indicated above.
Further candidate substrates are glass, metals and textiles.
11 220~8qO
With preference, at least one of the two substrates to be heat-sealed is made from plastic. With particularly preference, the substrate coated with a dispersion is made from aluminum. The plastic i8 eBpecially polystyrene, polyethylene terephtalate, 5 PVC, polyethylene or polypropylene.
~y means of heat-sealing it i8 possible to package articles, for example by coating an aluminum film with the heat-sealing lacquer in the form of dots or zones, and subsequently pressing this lO coated foil with, for example, a thermoformed plastic film so as to enclose an item to be packaged.
In the course of heat sealing, the substrates are pressed together by sealing jaws, which can be at 80-250~C. In the course 15 of this pressing operation, the pressures are generally from 0.1 to lO bar, in particular from 2 to 6 bar, with a pressing time (contact time) of at least 0.5 second, generally from 1 to 5 seconds.
20 The novel dispersions are notable for the fact that they bring about a seal of high sealed-seam strength, in particular between aluminum foil and polystyrene, polyethylene terephthalate, polyvinyl chloride and polyolefinic substances, including in particular ~ubstances of polypropylene and polyethylene; at the 25 same time, the film of sealing lacquer on its own possesses good blocking resistance.
Another notable feature of the novel dispersions is that they possess good adhesion to aluminum foil without the need for any 30 further primer coat on the aluminum surface.
Comparison Examples Comparison Examples 1 and 2 in accordance with US 5 385 967:
Copolymer I:
The copolymers I are water-soluble copolymers prepared by bulk polymerization following the method of DE-A-3 225 876.
For this preparation, 60 parts by weight of styrene and 40 parts by weight of acrylic acid were metered continuously into a 1 1 pressure vessel with a downstream pressure tube of twice the capacity, with a pressure regulator. The system was heated to 45 310~. The pressure was kept at between 5 and 50 bar and once was 22û08~0 varied within this range by means of a periodic pressure regulation over the course of one minute.
The residence time was 11 minutes; the copolymer melt was 5 discharged quantitatively at the same rate at fresh monomer mixture was supplied. The copolymer had a mean molecular weight Mn of 650 and a polydispersity U = MW/Mn -1 of 1.5.
Preparation of the copolymers II in the presence of the 10 copolymers I:
The amounts of an aqueous solution of the copolymers I as indicated in Table 1 were charged to a 3 1 four-neck flask fitted with reflux condenser, 2 feed vessels, a thermometer, a pilot 15 stirrer and gas inlet and outlet, the reaction vessel was flushed with nitrogen, and the solution was heated to 85~C. 54 g of a 1.5 % strength aqueous sodium peroxodisulfate solution were added, and then 1000 g of the monomers of copolymer II were run in at 85~C with stirring over the course of 2 h. At the same time, 20 in a separate feed, 126 g of a 1.5 % strength sodium peroxodisulfate solution were added dropwise over the course of 2.5 h. After the end of the two feeds, reaction was continued at 85~C for 1 h and then the reaction mixture was cooled to room temperature.
The polymer dispersions obtained by this procedure were free from coagulum. Their composition is shown in Table 1.
Comparison Examples 3 and 4 correspond to Examples 1 and 2 of 30 DE--A--39 21 256:
Mixture 1 was charged together with 260 g of isobutanol to a reaction vessel, and the resulting mixture was heated to 105~C.
Then mixture 2 was added, and the batch was polymerized at reflux 35 for 2.5 hours. Subsequently, mixture 3 was metered in at about 105~C over the course of 3 hours.
The batch was then polymerized at 105~C for 4 hours, during which it was diluted with 200 g of isobutanol. After it had cooled to 40 60~C, 35.4 g of 25 % strength by weight aqueous ammonia solution and then 850 g of water were stirred in. An isobutanol/water mixture was distilled off under reduced pressure until virtually no more isobutanol passed over. During the distillation, an amount of water corresponding to the amount of liquid removed by 45 distillation was added.
2200~90 Mixture 1:
Comp. Example 3 Comp. Example 4 5 Methyl methacrylate (g) 160 145 n-Butyl acrylate (g) 100 110 Acrylic acid (g) 20 25 Mixture 2:
tert-Butyl benzoate ~g) 1.5 1.5 15 tert-Butyl peroctoate (g) 1.5 1.5 Isobutanol (g) 30 30 20 Mixture 3:
Methyl methacrylate (g) 370 380 n-Butyl methacrylate (g) 350 340 tert-Butyl (g) 7.5 6.7 25 perbenzoate tert-Butyl peroctoate (g) 4.5 6.0 Isobutanol (g) 150 140 The composition is given in Tab. 1.
Comparison Example 5 3S As Comparison Example 5, the product Plexisol~ PM 555 from Rohm, Darmstadt was tested. This product is currently state of the art in terms of sealability with respect to polypropylene. It is a methacrylate/olefin-based emulsion in butyl acetate/methyl ethyl ketone.
Products of thi~ type are described in EP 023 978 (to Rohm). To ensure bond strength to aluminum foil, Rohm recommends a primer of PVC copolymers (eg. Vinylite VMCH from Union Carbide).
' 22no890 CO .~ ~,~
U ~ . . .
~r ~ e ~ '' ~d ~ ~ ~ ~
a. U' O c~
.~ ~i m r~ ~P
C~ I ~ I
~
X
W ~ _~
U
L H
H O
O O o o CO
.C r a~
O o -Ll O ~ 3 V~
~, 0 ~ m ~ ~ n ~J O C~ 0 3 :~: CO o 0 O _ ~ 0 C
G L. O O - a ~ ~ r ,- X Z t ) ~ U C~ U
Glass transition temperatures of the copolymers The glass transition temperatures were determined by differential 5 canning calorimetry in accordance with ASTM 3418/82. They can also be calculated approximately, using the Fox equation, from the glass transition temperatures of the monomers (T.G. Fox, Bull. Am.
Phys. Soc. Ser. II 1, (1956) 123).
10 Table 2: Glas~ transition temperatures in ~C [DSC]
Example Copolymer ICopolymer II
Cl 125 -26 20 Examples Polymer B was prepared in the presence of polymer A. The composition of polymers is shown in Table 3.
25 To do this, ethylene polymer A was charged to a 3 1 reaction flask with reflux condenser, 3 feed vessels, thermometer, pilot stirrer and nitrogen inlet. Together with 90 % by weight of the total amount of initiator system used (tert-butyl hydroperoxide, Na hydroxymethylsulfinate) and after nitrogen flushing, this 30 solution was heated to 70~C with stirring.
Subsequently, the monomers and the remaining amounts of initiator (0.8 % by weight t-BHP and 0.8 % by weight Na hydroxymethylsulfinate, based on monomers of copolymer B) were 35 added continuously with stirring over the course of 1.5 h. In Examples 1 to 10, the monomers were metered in in the sequence indicated in Table 3.
The batch was subsequently stirred at 70~C for one hour more and 40 then cooled to room temperature, to give coagulum-free dispersions whose composition and characteristic data are summarized in Table 3.
To give coagulum-free dispersions whose composition and 45 characteristic data are summarized in Table 3.
' ' 2200890 Table 3: Composition of the copolymers from the Examples Composition Quantitative Tg (~C) ratio Copol. B
Copol. A:B
Ex. No. Copol. A/ SC
Copol. B (%) 1 A 60 E/20 EHA/20 AA; NH3 33.4:66.6 13.6 34.1 B 50 nBA/50 S
2 A 60 E/20 EHA/20 AA NH3 33.4:66.6 63.2 34.4 B 20 nBA/80 S
3 A 60 E/20 ERA/20 AA; NH3 33.4:66.6 44.8 34.1 B 30 nBA/70 S
4 A 60 E/20 EHA/20 AA; NH3 43:57 44.8 33.8 B 30 nBA/70 S
A 60 E/20 EHA/20 AA; NH3 43:57 13.6 34 B 50 nBA/50 S
6 A 80 E/20 AA; DMEA33.4:66.6 13.6 34.4 B 50 nBA/50 S
7 A 80 E/20 AA DMEA 43:57 13.6 30 B 50 nBA/50 S
8 A 80 E/20 AA; N~333.4:66.6 13.6 35 B 50 nBA/50 S
9l) A 80 E/20 AA; NH333.4:66.6 13.6 33.7 B 50 nBA/50 S
A 80 E/20 AA; NH3 43:57 13.6 34.6 B 50 nBA/50 S
30 Key:
DMEA:
E: Ethylene EHA: Ethylhexyl acrylate 1) The polymers B were polymerized in the presence of an additional 10 % by weight, based on B, of a vinyl chloride-vinyl acetate-maleic acid copolymer from Union Carbide ~Vinylite VMCH).
Performance testing Description of the test methods:
1. Applying the lacquers The aqueous dispersions were coated using a 36 ~m doctor blade onto a 40 ~m thick aluminum (Al) foil, which is clean and untreated, and the coated foils were dried at 130~C for 3 minutes in a convection oven. The dry-film thickness was in the range 10-15 ~m (- 10-15 g/m2).
2. Sealing The coated Al foils were subjected to pressing with the polymer films (film thickness 250-300 ~m) indicated in Table 4, which possess the surface tensions indicated in that table, and are not treated further, in a welding apparatus of type HSG/ETK 525 from Brugger, with the application of pressure and temperature. The sealinq jaw~ were smooth and measured 150xlO mm. In the course of sealing, the lower jaw was adjusted to the stated temperature while the upper jaw remained unheated (at room temperature). The heated jaw contacted the Al foil while the cold jaw was against the polymer film. Sealing was carried out at 230~C (4 kp for a period of 4 seconds) and 220~C (4 kp, 1 second).
3. Sealed-seam strength The strength of the bond was measured in a tear tester from Frank, Model No. 81565, and is stated as the tear strength in N/10 mm. The tear off rate was 150 mm/min. With regard to tearing, two parameters are stated: Fmax, the ~; tearing force, and FM/N, the mean tear strength along the sealed seam (about 10-12 cm). (Results in Table 4).
4. 81Ocking resistance The blocking resistance was tested with the dry but unsealed lacquer surface on the Al foil under the conditions stated in the table (temperature, applied weight, duration). It was determined face to face, ie. coating against coating (in the Table c/c), then coating against uncoated Al foil (in the Table c/r: coating/reverse) and coating against an Al film coated with a nitrocellulose-based printing-ink binder (in the Table c/PI8: coating against printing-ink binder). The valuation is in accordance with a rating syctem: 1 = very good blocking resistance: the surface~ come apart again after weight is removed; 5 = very poor: the surfaces are stuck to one another and can be removed only with difficulty (re~ults in Table 5).
22008qo 5. Anticorrosion test Here, a drop of an aqueous solution comprising 70 parts by weight water, 20 parts by weight HCl (37 % strength) and 10 parts by weight CuS04 x H20 was allowed to fall on the lacquers which have been applied to Al foil and then dried (as described above). The test result is positive (+) if after 30 minutes there is no visible hole in the Al foil;
otherwise it is negative (-). (Results in Table 5).
Table 4: Sealability Sealing at 230~C Sealing at 220~C
Ex. No. PVC PET PS PS PS
(30-6 mN/m)* ~38.0 mN/M)* (29.8 mN/m)*(35.44 mN/m)*(35.44 mN/m)*
Fmax/FM/N Fmax/FM/N Fmax/FM/N Fmax/FM/N Fmax/FM/N
1 13.1/8.5 Rating: 3-4*** 17.0/14.5 7.3/5.5 2 none none 18.3/15.3 17.7/16.1 5.4/3.3 3 none none 19.8/15.3 7.2/4.3 4 none none 24.6/19.8 15.7/10.6 6.7/4.4 10.5/8.1 8.2/4.6 11.0/8.6Cohesion in PP II11.8/5.8 6 11.7/5.4 3.9/1.2 17.8/13.3 14.9/12.4 lO/3.6 7 9.4/3.3 Rating: 3-4 13.8/10.3 13.6/12.6 11.6/5.0 8 15.0/4.6 Rating: 4 20.0/16.3 12.5/10.9 9 21.7/7.9 4.9/2.0 22.2/16.7 12.6/10.8 4.1/3.1 7.9/4.1 Rating: 4 13.2/10.2 5.4/3.1 Comp. Ex. 13.3/2.9 4.5/3.3 4.9/3.0 9.1/5.3 4.1/2.7 Comp. Ex. 28.0/5.1 10.9/5.6 6.7/4.8 5.1/3.5 2.6/0.9 Comp. Ex. 33.8/2.9 2.8/2.0 6.2/4.5 Rating: 4 1.3/0.6 r~
Comp. Ex. 43.1/2.3 2.4/l.9 5.9/4.0 Rating: 4 l.0/0.4 O
PM 555 6.5/4.3 6.4/5.0 7.7/5.9 8.7/6.6 2.3/1.3 CX~
PM 555+Pr** 13.1/11.7 6.3/4.8 O
* Thi~ i~ the curface tension of the film ** A primer (adhesion promoter) wa~ used in addition to PM 555 *** Ratings of 3 to 5 are awarded if the tear strength F5n~ is < 1.0 N/10 mm (Rating 3 = poor, Rating 5 = very poor) Table 5: Blocking resistance and corrosion test Blocking resistance Blocking resistance Corrosion test15 h, 50~C, 1500 g 15 h, 40~C, 100 g HCl/CuS04 30'/RT
Ex. No. c/c c/r c/c c/PIB Damage 1 S 3 4 2 +
2 2 1 1 1 +
3 3 2 1-2 1 +
4 3 2 2 1 +
S 4 4 2 +
6 5 . 3- 4-5 2 +
7 5 2- 4-5 2 +
8 5 2 4-5 2 +
9 5 2 4-5 2 +
2-3 3 2 +
Comp. Ex. 3 1-2 2 1- + r~
No. 1 r~
Comp. Ex. 5 4 5 4 + oNo. 2 CX~
Comp. Ex. 4-5 4-5 4_5 4_5 + ~5~
No. 3 O
Comp. Ex. 4-5 4-5 4_5 4_5 +
No. 4 PM 555 3 1 1 1 +/-PM 555 + Pr. 3 1 1 1 +
A 60 E/20 EHA/20 AA; NH3 43:57 13.6 34 B 50 nBA/50 S
6 A 80 E/20 AA; DMEA33.4:66.6 13.6 34.4 B 50 nBA/50 S
7 A 80 E/20 AA DMEA 43:57 13.6 30 B 50 nBA/50 S
8 A 80 E/20 AA; N~333.4:66.6 13.6 35 B 50 nBA/50 S
9l) A 80 E/20 AA; NH333.4:66.6 13.6 33.7 B 50 nBA/50 S
A 80 E/20 AA; NH3 43:57 13.6 34.6 B 50 nBA/50 S
30 Key:
DMEA:
E: Ethylene EHA: Ethylhexyl acrylate 1) The polymers B were polymerized in the presence of an additional 10 % by weight, based on B, of a vinyl chloride-vinyl acetate-maleic acid copolymer from Union Carbide ~Vinylite VMCH).
Performance testing Description of the test methods:
1. Applying the lacquers The aqueous dispersions were coated using a 36 ~m doctor blade onto a 40 ~m thick aluminum (Al) foil, which is clean and untreated, and the coated foils were dried at 130~C for 3 minutes in a convection oven. The dry-film thickness was in the range 10-15 ~m (- 10-15 g/m2).
2. Sealing The coated Al foils were subjected to pressing with the polymer films (film thickness 250-300 ~m) indicated in Table 4, which possess the surface tensions indicated in that table, and are not treated further, in a welding apparatus of type HSG/ETK 525 from Brugger, with the application of pressure and temperature. The sealinq jaw~ were smooth and measured 150xlO mm. In the course of sealing, the lower jaw was adjusted to the stated temperature while the upper jaw remained unheated (at room temperature). The heated jaw contacted the Al foil while the cold jaw was against the polymer film. Sealing was carried out at 230~C (4 kp for a period of 4 seconds) and 220~C (4 kp, 1 second).
3. Sealed-seam strength The strength of the bond was measured in a tear tester from Frank, Model No. 81565, and is stated as the tear strength in N/10 mm. The tear off rate was 150 mm/min. With regard to tearing, two parameters are stated: Fmax, the ~; tearing force, and FM/N, the mean tear strength along the sealed seam (about 10-12 cm). (Results in Table 4).
4. 81Ocking resistance The blocking resistance was tested with the dry but unsealed lacquer surface on the Al foil under the conditions stated in the table (temperature, applied weight, duration). It was determined face to face, ie. coating against coating (in the Table c/c), then coating against uncoated Al foil (in the Table c/r: coating/reverse) and coating against an Al film coated with a nitrocellulose-based printing-ink binder (in the Table c/PI8: coating against printing-ink binder). The valuation is in accordance with a rating syctem: 1 = very good blocking resistance: the surface~ come apart again after weight is removed; 5 = very poor: the surfaces are stuck to one another and can be removed only with difficulty (re~ults in Table 5).
22008qo 5. Anticorrosion test Here, a drop of an aqueous solution comprising 70 parts by weight water, 20 parts by weight HCl (37 % strength) and 10 parts by weight CuS04 x H20 was allowed to fall on the lacquers which have been applied to Al foil and then dried (as described above). The test result is positive (+) if after 30 minutes there is no visible hole in the Al foil;
otherwise it is negative (-). (Results in Table 5).
Table 4: Sealability Sealing at 230~C Sealing at 220~C
Ex. No. PVC PET PS PS PS
(30-6 mN/m)* ~38.0 mN/M)* (29.8 mN/m)*(35.44 mN/m)*(35.44 mN/m)*
Fmax/FM/N Fmax/FM/N Fmax/FM/N Fmax/FM/N Fmax/FM/N
1 13.1/8.5 Rating: 3-4*** 17.0/14.5 7.3/5.5 2 none none 18.3/15.3 17.7/16.1 5.4/3.3 3 none none 19.8/15.3 7.2/4.3 4 none none 24.6/19.8 15.7/10.6 6.7/4.4 10.5/8.1 8.2/4.6 11.0/8.6Cohesion in PP II11.8/5.8 6 11.7/5.4 3.9/1.2 17.8/13.3 14.9/12.4 lO/3.6 7 9.4/3.3 Rating: 3-4 13.8/10.3 13.6/12.6 11.6/5.0 8 15.0/4.6 Rating: 4 20.0/16.3 12.5/10.9 9 21.7/7.9 4.9/2.0 22.2/16.7 12.6/10.8 4.1/3.1 7.9/4.1 Rating: 4 13.2/10.2 5.4/3.1 Comp. Ex. 13.3/2.9 4.5/3.3 4.9/3.0 9.1/5.3 4.1/2.7 Comp. Ex. 28.0/5.1 10.9/5.6 6.7/4.8 5.1/3.5 2.6/0.9 Comp. Ex. 33.8/2.9 2.8/2.0 6.2/4.5 Rating: 4 1.3/0.6 r~
Comp. Ex. 43.1/2.3 2.4/l.9 5.9/4.0 Rating: 4 l.0/0.4 O
PM 555 6.5/4.3 6.4/5.0 7.7/5.9 8.7/6.6 2.3/1.3 CX~
PM 555+Pr** 13.1/11.7 6.3/4.8 O
* Thi~ i~ the curface tension of the film ** A primer (adhesion promoter) wa~ used in addition to PM 555 *** Ratings of 3 to 5 are awarded if the tear strength F5n~ is < 1.0 N/10 mm (Rating 3 = poor, Rating 5 = very poor) Table 5: Blocking resistance and corrosion test Blocking resistance Blocking resistance Corrosion test15 h, 50~C, 1500 g 15 h, 40~C, 100 g HCl/CuS04 30'/RT
Ex. No. c/c c/r c/c c/PIB Damage 1 S 3 4 2 +
2 2 1 1 1 +
3 3 2 1-2 1 +
4 3 2 2 1 +
S 4 4 2 +
6 5 . 3- 4-5 2 +
7 5 2- 4-5 2 +
8 5 2 4-5 2 +
9 5 2 4-5 2 +
2-3 3 2 +
Comp. Ex. 3 1-2 2 1- + r~
No. 1 r~
Comp. Ex. 5 4 5 4 + oNo. 2 CX~
Comp. Ex. 4-5 4-5 4_5 4_5 + ~5~
No. 3 O
Comp. Ex. 4-5 4-5 4_5 4_5 +
No. 4 PM 555 3 1 1 1 +/-PM 555 + Pr. 3 1 1 1 +
Claims (11)
1. A method for heat-sealing substrates, which comprises coating a substrate with an aqueous dispersion comprising an ethylene polymer A), with at least 20 % by weight of ethylene and at least 5 % by weight of an ethylenically unsaturated acid, and a free-radically polymerized polymer B), and pressing the coated substrate with a second substrate at elevated temperature.
2. A method as claimed in claim 1, wherein the temperature is from 80 to 300°C and pressing is carried out at from 0.1 to 10 bar.
3. A method as claimed in claim 1 or 2, wherein the ethylene polymer consists of from 20 to 95 % by weight of ethylene, from 5 to 80 % by weight of an ethylenically unsaturated acid, and from 0 to 60 % by weight of further monomers.
4. A method as claimed in any of claims 1 to 3, wherein the polymer B) consists of from 30 to 100 % by weight of monomers referred to as principal monomers, selected from C1-C20 alkyl (meth)acrylates, C8-C12 vinyl-aromatic compounds, vinyl esters of carboxylic acids of 1 to 20 carbons, and ethylenically unsaturated nitriles, from 0 to 30 % by weight of an ethylenically unsaturated acid or anhydride, from 0 to 20 % by weight of ethylenically unsaturated compounds having a crosslinking action, and from 0 to 70 % by weight of further monomers.
5. A method as claimed in any of claims 1 to 4, wherein the polymer B) is prepared by emulsion polymerization in the presence of ethylene polymer A).
6. A method as claimed in any of claims 1 to 5, wherein a substrate of plastic or metal is coated with the aqueous dispersion and the substrate thus coated is pressed with a second substrate at elevated temperature.
7. An aqueous dispersion comprising an ethylene polymer A) and a free-radically polymerized polymer B), polymer B) being prepared by emulsion polymerization in the presence of ethylene polymer A).
8. An aqueous dispersion as claimed in claim 7, wherein the ethylene copolymer consists of from 20 to 95 % by weight of ethylene from 5 to 80 % by weight of an ethylenically unsaturated acid, and from 0 to 60 % by weight of further monomers.
9. An aqueous dispersion as claimed in claim 8, wherein the polymer B consists of from 30 to 100 % by weight of monomers referred to as principal monomers, selected from C1-C20 alkyl(meth)acrylates, C8-C12 vinyl-aromatic compounds, vinyl esters of carboxylic acids of 1 to 20 carbons, and ethylenically unsaturated nitriles, from 0 to 30 % by weight of an ethylenically unsaturated acid or anhydride from 0 to 20 % by weight of ethylenically unsaturated compounds having a crosslinking action, and from 0 to 70 % by weight of further monomers.
10. The use of an aqueous dispersion comprising an ethylene polymer A), with at least 20 % by weight of ethylene and at least 5 % by weight of an ethylenically unsaturated acid, and a free-radically polymerized polymer B) as heat-sealing lacquer.
11. The use as claimed in claim 10, wherein the aqueous dispersion is as claimed in claim 7.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19611669A DE19611669A1 (en) | 1996-03-25 | 1996-03-25 | Use of aqueous dispersions as heat seal lacquer |
| DE19611669.4 | 1996-03-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2200890A1 true CA2200890A1 (en) | 1997-09-25 |
Family
ID=7789301
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002200890A Abandoned CA2200890A1 (en) | 1996-03-25 | 1997-03-24 | Use of aqueous dispersion as heat-sealing lacquer |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0798357B1 (en) |
| JP (1) | JPH106426A (en) |
| KR (1) | KR970065619A (en) |
| AT (1) | ATE183540T1 (en) |
| CA (1) | CA2200890A1 (en) |
| DE (2) | DE19611669A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10041634C2 (en) * | 2000-08-24 | 2002-10-17 | Basf Coatings Ag | Aqueous dispersion and its use for the production of coating materials, adhesives and sealants curable thermally and with actinic radiation |
| AT411044B (en) * | 2001-10-16 | 2003-09-25 | Burg Design Gmbh | DECOR ELEMENT |
| WO2011003864A1 (en) | 2009-07-09 | 2011-01-13 | Basf Se | Cold-sealable polymer dispersion produced by emulsion polymerization in the presence of an ethylene/(meth)acrylic acid copolymer |
| US20130156987A1 (en) | 2011-12-20 | 2013-06-20 | Fofitec Ag | Multilayer material, method for production thereof and printing stock produced therewith |
| WO2015180960A1 (en) | 2014-05-27 | 2015-12-03 | Amcor Flexibles Rorschach Ag | Heat-sealable structure for aluminum disposable beverage-brewing containers |
| EP3871997A1 (en) | 2020-02-25 | 2021-09-01 | CCL Label AG | Container with flexible packaging bag |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53147744A (en) * | 1977-05-30 | 1978-12-22 | Mitsui Petrochem Ind Ltd | Synthetic resin aqueous dispersion composition |
| JPS57147564A (en) * | 1981-03-06 | 1982-09-11 | Kuraray Co Ltd | Adhesive composition |
| DE3321797A1 (en) * | 1983-06-16 | 1984-12-20 | Röhm GmbH, 6100 Darmstadt | HOT SEALABLE COATINGS |
| JPH04253784A (en) * | 1991-02-05 | 1992-09-09 | Hoechst Gosei Kk | Pressure-sensitive adhesive |
-
1996
- 1996-03-25 DE DE19611669A patent/DE19611669A1/en not_active Withdrawn
-
1997
- 1997-03-17 DE DE59700339T patent/DE59700339D1/en not_active Expired - Lifetime
- 1997-03-17 AT AT97104487T patent/ATE183540T1/en not_active IP Right Cessation
- 1997-03-17 EP EP97104487A patent/EP0798357B1/en not_active Expired - Lifetime
- 1997-03-24 CA CA002200890A patent/CA2200890A1/en not_active Abandoned
- 1997-03-24 JP JP9069337A patent/JPH106426A/en not_active Withdrawn
- 1997-03-24 KR KR1019970010053A patent/KR970065619A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0798357B1 (en) | 1999-08-18 |
| JPH106426A (en) | 1998-01-13 |
| KR970065619A (en) | 1997-10-13 |
| ATE183540T1 (en) | 1999-09-15 |
| DE19611669A1 (en) | 1997-10-02 |
| EP0798357A1 (en) | 1997-10-01 |
| DE59700339D1 (en) | 1999-09-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |