Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/29—Laminated material
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
  • C09J2301/16—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the structure of the carrier layer
  • C09J2301/162—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the structure of the carrier layer the carrier being a laminate constituted by plastic layers only
• • 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
  • C09J2409/00—Presence of diene rubber
  • C09J2409/006—Presence of diene rubber in the substrate
• • 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
  • C09J2423/00—Presence of polyolefin
  • C09J2423/006—Presence of polyolefin in the substrate
• • 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
  • C09J2433/00—Presence of (meth)acrylic polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree

Definitions

• the present invention relates to a multilayer adhesive tape which can be used in particular as a tear strip.
• Tear strips are known and serve in various forms as an opening aid on the one hand for cigarette packs, confectionery packaging and similar packaging, which are wrapped with a film, on the other hand for cardboard such as detergent packaging.
• the tear strip is attached to the package so that you pull to open on the tear strip and thus destroys the wrapping film or cardboard at the desired location.
• tear strips are in use, which are equipped on one side with a hotmelt-based adhesive.
• a hotmelt-based adhesive For example, these are described in US 3,187,982 A, US 3,311 1, 032 A or CA 749 198 A.
• a tear strip which is self-adhesive.
• a monoaxially stretched carrier film which is equipped with a self-adhesive layer on one side and a silicone release layer on the other side.
• a print under one of the two layers is a print.
• Such or similar structures are known for the production of pressure-sensitive adhesive tapes, for example from DE 21 04 817 A, US 3,088,848 A, US 3,482,683 A or US 2,956,904 A. Not disclosed in these documents is the use of such film structures for self-adhesive tear strips.
• the usage of Self-adhesive tapes of this kind as a tear strip is mentioned in the magazine "Packaging Review" of February 1973, page 57.
• a self-adhesive tear strip consisting of a carrier film, a release layer, an adhesive layer facing away from the release layer and optionally a pressure under the adhesive or release layer.
• the strip is characterized in that the carrier film consists of a stretched film, that the release and adhesive layer of aqueous solution, emulsion or dispersion are applied and that release layer, ink and adhesive layer on a relation to the tear strip by a much wider film in one operation be applied on a machine.
• Usual for use as an opening aid of film packaging are at least monoaxially, preferably biaxially stretched at least single-layer 15 to 60 microns thick carrier films.
• Self-adhesive or heat-activatable tear strips of longitudinally stretched polypropylene film are used for the tearing of cardboard boxes for a long time. They are available in foil thicknesses of 50 to 140 ⁇ m. Film thicknesses greater than 85 ⁇ m are used when opening particularly heavy cardboard. More common are tear strips in thicknesses between 60 and 90 microns.
• Tear tabs based on a monoaxially stretched polypropylene backing often use a special polymer blend optimized for tearing performance, resulting in tensile strengths in the longitudinal direction of from 230 to 330 N / mm 2 .
• polypropylene tear strips preferably in the range of 60 to 65 ⁇ m, exhibit perfect tear-open behavior in all corrugated paperboard cartons, including microwell paperboard. This applies regardless of whether it is torn open exactly in the direction of the glued strip.
• a trend in the tear tape market is the departure from the film recipe optimized for the tearing performance.
• a reduced Aufrcet alloy here is accepted accepting in order to achieve in return improved machinability of the tear strip during its application.
• a reduction in the toughening additives can be made below the amount recommended for optimal tearing performance, until completely eliminated.
• Heavy full-board grades of about 1000 g / m 2 can only be torn open in the optimum direction of tear. When deviating from this direction, tearing may occur during the tearing operation due to the asymmetrical loading of the strip from the more heavily loaded edge of the strip.
• the frequency of the breaks is influenced, for example, by inhomogeneities in the film, by micro-slits in the cut edges of the film strips, by wood particles or by particularly solidified particles in the cardboard and similar phenomena. In addition, the tearing speed has an influence.
• full board between 450 and 600 g / m 2 basis weight are used to a greater extent, which may have a wax-impregnated intermediate layer, but in any case with a laminated top layer of high gloss cast chromolux papers are provided.
• These boards can be torn open with the polypropylene tear strips only with a similarly poor result as the above-mentioned 1000 g / m 2 - solid board.
• EP 0 269 967 A1 discloses a tear strip having a carrier stretched in a predominantly one direction and provided with an adhesive layer, wherein the carrier consists of at least one base layer which is provided with at least one tough layer which is tougher than the one base layer.
• the carrier consists of at least one base layer which is provided with at least one tough layer which is tougher than the one base layer.
• a tear strip with a stretched in a predominantly one direction carrier which is provided with an adhesive layer
• the carrier at least one containing a polypropylene-olefin copolymer and / or a polypropylene impact additive mixture base layer, which is provided with at least one polypropylene-containing tough layer containing an impact additive and is tougher than the base layer.
• Adhesive tapes are known for cover and surface protection films, which have a carrier consisting entirely or partially of PE (polyethylene) and an adhesive based on an acrylate dispersion.
• TPP equivalent monoaxially stretched polypropylene
• MOPP monoaxially stretched polypropylene
• the coil up to about 15 kg, to which the tear-strip is custom-made, is accelerated abruptly and jerkily Even in continuous operation tensile strains of more than 8 N often act on the tear-open strip. This includes the use of unbacked or auc h biaxially oriented polypropylene.
• the invention has for its object to provide an adhesive tape, which is particularly suitable as a tear strip, which thus has an oriented, predominantly longitudinal carrier film which ensures optimum tear results in the use as tear strips with the smallest possible thickness, even if the tearing direction deviates from the direction of the glued tape
• the invention relates to an adhesive tape having a carrier stretched in a predominantly one direction, wherein the carrier has at least one base layer which is provided with at least one outer impact-resistant layer which is tougher than the base layer, the base layer on the side opposite the outer layer is provided with an adhesive layer based on an aqueous acrylate dispersion and the outer layer has no release coating on the free side.
• this layer fulfills the essential function of the invention, namely the possible omission of a release layer. It is preferred if the support consists of a polypropylene-olefin copolymer and / or a polypropylene.
• the base layer or the base layers are preferably predominantly, preferably at least 70 wt .-% of a polypropylene having a high, preferably at least 70% isotactic content.
• a polypropylene having a high, preferably at least 70% isotactic content Preferably, random or block copolymers of propylene and olefins are used. Particular preference is given to using propylene / ethylene copolymers which contain copolymerized up to 20% by weight of ethylene.
• the base layer (s) may consist of 100% propylene-olefin copolymers, or may be admixed with these copolymers, preferably containing up to 25% by weight of an impact modifier suitable for impact tensile toughness of polypropylene stretched in the web direction perpendicular to improve.
• Preferred additives are low density polyethylene, in particular linear low density polyethylene (LLDPE), thermoplastic rubbers such as butadiene-styrene copolymers (SBS) or isoprene-styrene copolymers (SIS), in particular in each case their block copolymers, or ethylene-vinyl acetate copolymers (EVA ).
• the base layers may also consist of polypropylene homopolymer, to which an impact additive is then admixed, preferably at least 10% by weight, preferably at most 30% by weight.
• the impact additives are preferably added individually. However, mixtures of the specified impact additives are also usable.
• the base layers preferably contain from 75% by weight to 100% by weight of copolymer and from 25% by weight to 0% by weight of LLDPE or from 80% by weight to 100% by weight of copolymer with from 20% by weight to 0 %
• thermoplastic rubber in particular SBS, or 75% by weight to 100% by weight of copolymer and 25% by weight to 0% by weight of EVA, especially however, preferably 80% to 95% by weight of copolymer and 5% to 20% by weight of LLDPE or 85 to 95% by weight of copolymer and 5% to 15% by weight of thermoplastic rubber , in particular SBS, or 85 wt .-% to 95 wt .-% of copolymer and 5 wt .-% to 15 wt .-% EVA.
• the adhesive facing away from the outer layer of the tear strip material mixtures are used, which preferably contain much higher levels of Schlagzähzusatzes than the base layer and thus simultaneously ensure a higher impact resistance and an appropriate rolling behavior of this outer layer. It is preferably used up to 50 wt .-% of a propylene-olefin copolymer or a propylene homopolymer, as indicated for the base film.
• the proportion of the ethylene polymer may be 50% by weight to 100% by weight, but preferably 60% by weight to 80% by weight.
• the same single impact additive is used in base layers and the tough layer.
• the use of different individual toughening additives or the same or different mixtures of impact additives is also possible.
• Suitable polyethylenes are LDPEs, metallocene PEs, but especially linear low density polyethylenes (LLDPE).
• LLDPE linear low density polyethylene
• the preferably used linear low density polyethylene (LLDPE) is a specific ethylene copolymer having a density of 0.910 to 0.935 g / cm 3 which has been copolymerized using an olefin containing at least three carbon atoms (see L. Schwiegk: " LLDPE - a new polyethylene ", Plastverarbeiter 33rd year 1982, No. 9, pages 1035 to 1037).
• the support is obtained by extrusion and uniaxial stretching, preferably by coextruding the layers into a coextruded primary film and then stretching the primary film in at least one direction, using conventional, well-known methods. Preferably, it is stretched in the longitudinal direction.
• the draw ratio in the stretching of the coextruded primary film in the longitudinal direction is preferably 1: 5 to 1: 9, more preferably 1: 6.5 to 1: 7.5.
• the stretch ratio indicates that a section of 6 m length of the stretched film is formed from a section of the film of, for example, 1 m in length (draw ratio 1: 6).
• Other terms are also known for the term "direction of orientation", for example: longitudinal direction, machine direction, stretching being effected without the width of the primary film decreasing substantially, solely at the expense of the thickness of the film.
• the thickness of the stretched carrier can be 50 to 140 ⁇ m, preferably 60 to 120 ⁇ m, particularly preferably 65 to 90 ⁇ m.
• the proportion of the base layer or base layers combined amounts to 50 to 95%, for a wear-optimized carrier preferably 65 to 75% of the total thickness of the carrier.
• the proportion of the basic base layer can be increased up to 95%.
• two or more tough layers can be applied on both surfaces of the base layer and on top of each other.
• an adhesive based on an aqueous acrylate dispersion is applied to the backing on one side.
• the surface can be pretreated by methods commonly used for polyolefin surfaces, for example, corona or flame pretreatment. Special anchoring layers can also be used.
• Aqueous acrylate dispersions are known and are used both for adhesives of adhesive tapes and for adhesives of labels in large quantities.
• the acrylate dispersions contain particles of acrylate polymers which are dispersedly dispersed in the aqueous phase of the dispersion.
• Acrylate dispersions are prepared in an aqueous medium by polymerization of suitable monomers. The preparation can be carried out either by batch process or by metering one or more components during the polymerization. During the batch process, all required components are presented simultaneously.
• the properties of the acrylate dispersions and the corresponding adhesives are determined predominantly by the choice of monomers and the molecular weight achieved.
• Suitable monomeric building blocks are described in "Acrylic Adhesives", Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, Second Edition, edited by Donatas Satas, Van Nostrand Reinhold New York, pages 396-456.
• inventively preferred acrylate dispersions contain in particular
• acrylate dispersions are used with 0.5 to 3 wt .-% acrylic acid units. In a further preferred embodiment
• Another example of acrylate dispersions according to the invention are acrylate dispersions with
• the acrylate dispersions may additionally contain further monomer units, by means of which, for example, the glass transition temperature and the crosslinkability can be controlled.
• further monomer units by means of which, for example, the glass transition temperature and the crosslinkability can be controlled. Examples are methyl acrylate, ethyl acrylate, methyl ethyl acrylate, maleic anhydride, acrylamide, glycidyl methacrylate, isopropyl acrylate, n-propyl acrylate,
• the acrylate dispersions usually contain 0 to 10 wt .-% of these additional
• Monomer units either exclusively an additional monomer unit or mixtures thereof are used.
• the solids content of the acrylate dispersions is in particular between 40 and 70
• Wt .-% preferably between 45 and 65 wt .-%.
• the acrylate dispersions which can be used according to the invention are called Primal PS 83d or Primal PS 90 from Rohm & Haas.
• the dispersion may contain other additives such as fillers or crosslinking agents.
• Suitable crosslinking agents may be epoxy resins, amine derivatives such as hexamethoxymethylmelamine and / or condensation products of an amine, for example melamine, urea with an aldehyde, for example formaldehyde.
• the adhesives used for the production of the adhesive tapes according to the invention may contain further components if these are chosen so that the properties (in particular adhesion and water insensitivity) are not thereby impaired.
• examples are resins, plasticizers, dyes, defoamers and thickeners and other additives to adjust the desired rheological behavior.
• Modifications of acrylate dispersions are known and described, for example, in "Modification of Acrylic Dispersions", Alexander Zettl in Handbook of Pressure Sensitive Adhesive Technology, Second Edition edited by Donatas Satas, Van Nostrand Reinhold New York, pages 457-493.
• the adhesive can be optimized by using crosslinkers in the direction of higher shear strength. Selection and proportion of crosslinkers is known to the skilled person and can be determined by appropriate experiments.
• Crosslinking agents for acrylate dispersions are generally known and described, for example, in "Acrylic Adhesives", Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, Second Edition, edited by Donatas Satas, Van Nostrand Reinhold New York, pages 41 1 to 419.
• Crosslinking agents based on isocyanate are generally suitable, but not preferred because of the limited pot life and the increased cost of occupational safety.
• An example of crosslinking agents based on isocyanate is Basonat F DS 3425 X (BASF).
• isocyanate-free crosslinkers for example crosslinkers based on salts of polyfunctional metals. These are basically known and are described, for example, in US Pat. Nos. 3,740,366, 3,900,610, 3,770,780 and 3,790,553. Particularly suitable are crosslinkers based on zinc complexes which can form covalent and / or complex-like bonds with carboxyl groups.
• the invention also provides the process for producing the adhesive tape according to the invention.
• the adhesive tapes can be produced by known processes. An overview of common manufacturing processes can be found, for example, in "Coating Equipment”, Donatas Satas in Handbook of Pressure Sensitive Adhesive Technology, Second Edition, edited by Donatas Satas, Van Nostrand Reinhold New York, pages 767 to 808. The known methods for drying and cutting The adhesive tapes can also be found in the Handbook of Pressure Sensitive Adhesives Technology pages 809-874.
• the coating of the support with dispersion adhesives is preferably carried out with wire doctor systems, which are adjusted so that the desired application is achieved.
• the subsequent drying of the coated film takes place in particular in the drying channel, which is operated with hot air. In principle, an additional drying by means of infrared radiators is possible.
• the adhesive tape rolls should be wound up with even tension and even pressure.
• the optimization of winding is dependent on the equipment used and known in the art.
• the tape can be excellently used as a tear strip.
• the adhesive tape has an economic advantage because a release can be omitted.
• silicone commonly used for tear tape is sometimes considered critical, sometimes requiring silicone freeze of products as such (for example, in the Japanese food industry). Furthermore, silicone causes problems due to silicone transfer. In the case of tear strips, printed boards which were in contact with the back of the tear strip in the stack occasionally experience distortions in the printed image. The unrolling characteristic is advantageous for use at high speeds (corrugated cardboard systems usually run with> 150 min, up to 300 m / min).
• adheresive tape encompasses all flat structures such as films or film sections which are expanded in two dimensions, tapes of extended length and limited width, tape sections, diecuts, labels and the like.
• MFR Melt Flow Ratio
• This primary film is fed via Vortexwalzen a Walzenreckwerk conventional design and longitudinally stretched at temperatures of 100 to 135 0 C in the ratio 1: 7.5.
• the resulting film has a thickness of 83 to 87 microns and after edge trim a width of 1200 mm.
• the proportion of the mixture I in the total thickness is 60 to 63 microns.
• the stretched overall film has a tensile force at 10% elongation of 85 N / cm in the longitudinal direction, a tensile strength of 180 N / cm and an elongation at break of 60%.
• a pressure-sensitive adhesive is applied.
• a primer which improves the adhesion of the adhesive to the film is first applied at a coating weight of 0.75 g / m 2 .
• an adhesive having a basis weight of 28 g / m 2 is overcoated on the corona pretreated surface of the base layer. This is an acrylate dispersion with 82.5 wt .-% poly-2-ethylhexyl acrylate
• the coated carrier webs are cut on special cutting machines to 4 mm wide tear strips and wound in the usual way to 35,000 m long large rolls.
• the thickness of the coextrusion layer is reduced to 5 ⁇ m.
• the resulting total thickness of the carrier is 68 ⁇ m.
• the stretched total film points in Longitudinal tensile force at 10% elongation of 70 N / cm, a breaking strength of 175 N / cm and an elongation at break of 45%.
• a primer which improves the adhesion of the adhesive to the film is first applied at a coating weight of 0.75 g / m 2 .
• an adhesive having a basis weight of 30 g / m 2 is then overcoated on the corona pretreated surface of the base layer.
• This is an acrylate dispersion with 63 wt .-% poly-n-butyl acrylate
• a mixture II of 30 parts by weight of the abovementioned polypropylene copolymer with 67 parts by weight of the above-stated polyethylene copolymer and 3 parts by weight of the color masterbatch is likewise melted.
• Both extruders are matched to one another after drawing in a ratio of 1: 6, 8, the film obtained has a thickness of 62 to 65 microns.
• the proportion of the mixture I in the total thickness is 48 to 49 microns, the proportion of the mixture Il in the total thickness is 14 to 15 microns.
• the stretched overall film has a tensile force at 10% elongation of 65 N / cm in the longitudinal direction, a tensile strength of 145 N / cm and an elongation at break of 50%.
• a primer which improves the adhesion of the adhesive to the film is first applied at a coating weight of 0.75 g / m 2 .
• Side extruder lower throughput is a mixture II of 35 GT of the above polypropylene copolymer with 65 GT of the above
• Polyethylene copolymer also melted and extruded and coated as shown in Example 2.
• the stretched overall film has a tensile force at 10% elongation of 110 N / cm in the longitudinal direction, a tensile strength of 235 N / cm and an elongation at break of 35%.
• This primary film is fed via Vortexwalzen a Walzenreckwerk conventional design and longitudinally stretched at temperatures of 100 to 135 0 C in the ratio 1: 7.5.
• the resulting film has a thickness of 62 to 64 microns.
• the stretched film has a tensile force at 10% elongation of 70 N / cm in the longitudinal direction, a tensile strength of 170 N / cm and an elongation at break of 40%.
• This double-sided corona-pretreated film is provided on one side with a silicone release and coated on the other side with a pressure-sensitive adhesive as in Example 2.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Adhesive Tapes (AREA)
• Laminated Bodies (AREA)

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• 2006
  • 2006-12-21 DE DE102006061812A patent/DE102006061812A1/de not_active Withdrawn
• 2007
  • 2007-12-05 JP JP2009541960A patent/JP2010513623A/ja not_active Withdrawn
  • 2007-12-05 WO PCT/EP2007/063362 patent/WO2008077729A1/de active Application Filing
  • 2007-12-05 US US12/516,848 patent/US20100055426A1/en not_active Abandoned
  • 2007-12-05 CA CA002672923A patent/CA2672923A1/en not_active Abandoned
  • 2007-12-05 EP EP07857260A patent/EP2121863A1/de not_active Withdrawn

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