CN111433304A

CN111433304A - Use of adhesive tape for connecting plate elements in an articulated manner

Info

Publication number: CN111433304A
Application number: CN201880078479.7A
Authority: CN
Inventors: S.伯恩特
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2017-12-04
Filing date: 2018-12-03
Publication date: 2020-07-17
Also published as: WO2019110498A1; DE102017221759B3; EP3720919A1

Abstract

The invention relates to the use of adhesive tape for connecting plate elements in an articulated manner. The adhesive tape is applied in such a way that it bridges the gap between the adjacent edges of the two panel elements, wherein the adhesive tape has a carrier made of a film on one side of which an adhesive based on acrylate is applied in the form of a dry polymer dispersion, said film being a biaxially oriented film made of polypropylene, polyethylene or polyester, such as PET, the polymers of said polymer dispersion consisting of: c)95.0 to 100.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate and d)0.0 to 5.0% by weight of an ethylenically unsaturated monomer having acid or anhydride functional groups, a release layer, in particular a urethane-based release layer, being provided on the side of the carrier which is not coated with adhesive.

Description

Use of adhesive tape for connecting plate elements in an articulated manner

The invention relates to the use of an adhesive tape for the articulated connection of panel elements, wherein the adhesive tape is applied in such a way that it bridges the gap (slit) between the adjacent edges of two panel elements, so that the pivot axis is in the area of the adhesive tape.

Plate elements, preferably fibre plates, are known from the prior art and are used, for example, as elements for portable furniture

The cabinet back panel of (1). These are connected to each other and fixed to the rear of the cabinet by means of separate connecting elements, for example grooved plastic rails, in which the plate elements are pushed into the grooves.

Foldable panels are important elements of portable furniture, in particular cabinet furniture. They have a significant advantage over the use of two separate plates as back panels, since they form dust-proof connections and cannot be displaced relative to each other in the presence of pushing or pulling forces. The foldable back panel can be folded to half its original area by folding the panel element and can be packed in this way relatively space-saving.

Foldable panels of this type are made, for example, from hard fiberboard, particle board, MDF or HDF board.

The composition of a typical MDF board is as follows (reported in weight percent):

80-83% Wood

9-10.5% adhesive

0.5-2.5% of additives and

6-8% water.

The panels have, for example, high-quality sides (Gutseite) which are coated or painted with plastic and which, in the assembled furniture part, are intended to face the interior of the furniture part, and a more or less untreated back side. The foldability has the additional advantage that the panel elements can be stacked facing each other with high quality faces so that they are protected from damage during handling, packaging and transport.

The fibre boards are at least partially connected to each other along the connecting edges by means of an adhesive or adhesive strip, preferably based on polyurethane. As a result of this construction, the two panel elements form a foldable unit. In the area of the adhesive strip there is a pivot about which the two plate elements can be folded or pivoted.

The connection of the panel elements is also achieved in particular using single-sided adhesive tape.

Half of the single-sided adhesive tape is attached to one edge of the first plate element in such a way that, in terms of the width of the tape, substantially half of the self-adhesive remains available for adhesive bonding with the edge of the second plate element. Advantageously, the single-sided adhesive tape is provided with a centrally cut release paper or covering paper, so that the adhesive bonding operation can be carried out continuously, wherein in each case only a part (segment) of the release paper is removed. The tape segment is preferably applied mechanically.

In order to be able to withstand high tensile forces, adhesive tapes based on glass-wool fabrics are used. However, when using an adhesive tape with a glass wool fabric, there is a risk that: the filaments break during folding of the back panel and lose their stabilizing effect.

WO 2005/052438 a2 discloses a foldable board having at least two board elements which are hingedly connected by means of an adhesive layer along mutually adjacent connecting edges having a right-angled contour, such that the board elements can be folded about an axis, wherein in the folded state the board elements are superimposed flush with their connecting edges and the adhesive layer is at least partially adhesively applied to the connecting edges of the respective board elements. In the unfolded state, the adhesive-coated connecting edges butt against each other. As the adhesive layer, a curable elastic polyurethane adhesive is proposed.

For process reasons, PU adhesives have the following disadvantages: it must be ensured that it is applied precisely between the two back panels. Very precise processing is necessary here. In addition, liquid adhesives must always be cured for a period of time to develop their full performance. The adhesive tape does not have this disadvantage. The use of adhesive tape thus makes it possible to save considerable time (and in particular also costs in mass production). Furthermore, the adhesive bond is not as stressed as adhesive bonding using adhesive tape.

The hinged connection of the plate elements uses silk adhesive tapes, i.e. tapes in which the carrier is reinforced with woven or textile fabric made of filaments, in particular glass filaments. These have the following disadvantages: the adhesive tape is also folded during the folding of the back panel. This "buckling stress" (of the tape) breaks the glass fibers, which therefore no longer provide reinforcement.

Tapes based on synthetic rubber adhesives can ensure a high instantaneous adhesive strength (adhesion) which hardly increases or decreases even during storage in climates (where the adhesive bond strength tends to decrease). However, these adhesives are not as age stable as acrylate adhesives.

The object of the present invention is to provide an adhesive tape for the articulated web elements which has all the required mechanical properties, in particular for use under high stress (load).

This object is achieved by the use of an adhesive tape as characterized in detail in the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

The invention therefore relates to the use of an adhesive tape for the hinged connection of panel elements, wherein the adhesive tape is applied in such a way that it bridges the gap between the adjacent edges of two panel elements, wherein

The adhesive tape has a support made of a film: on one side of the support a pressure-sensitive adhesive in the form of an acrylate-based dry polymer dispersion is applied,

the film is a biaxially oriented film made of polypropylene, polyethylene or polyester, such as PET,

the polymer of the polymer dispersion consists of:

(a)95.0 to 100.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

(b)0.0 to 5.0% by weight of an ethylenically unsaturated monomer having acid or anhydride functionality

And a release layer, in particular a urethane-based release layer, is present on the side of the carrier that is not coated with adhesive.

The adhesive tape is thus applied in such a way that it bridges the gap between the adjacent edges of the two plate elements, so that the pivot axis is in the area of said adhesive tape.

In the case where three (or more) panel members are to be joined, the panel members may be folded in a zigzag folded (also known as L eporello fold), wound (wickerfeltung) or windowed folded form (also known as jar fold (Triptychon)), it is preferred when tape is applied all the way to the inside of the created fold (fold) to avoid as much over-stretching of the carrier during folding as possible.

It is further preferred when the board element is a fiberboard, in particular a hardboard, a chipboard, an MDF board or an HDF board. MDF boards are particularly preferred.

In a particularly advantageous variant of the invention, the plate element forms a cabinet back panel, wherein one or more folds (folds) in the cabinet back panel can be arranged horizontally, vertically and both horizontally and vertically.

Due to special mechanical requirements, oriented film supports are used for adhesive tapes. The targeted influence of the mechanical properties is permitted by the orientation, i.e. the stretching of the initially formed primary film in one or more preferred directions during the production process. So-called biaxially oriented films may be drawn sequentially, wherein after being formed by extrusion with a slot die (nozzle), the primary film is initially drawn in the machine direction by being directed around a series of rollers, wherein the film is conveyed at a speed greater than the speed upon exiting the extrusion die. The film is then stretched transversely in a stretching apparatus. Stretching of the film in two directions can also be performed in one step (see e.g. US 4,675,582A and US 5,072,493 a).

It is also known to stretch BOPP supports during film blowing.

The working principle of orientation results from the orientation (alignment) of the polymer molecular chains and the crystalline structure formed therefrom as well as the orientation of the amorphous regions in a particular preferred direction and the strength increase associated therewith. In principle, however, the strength also decreases in the direction in which no orientation takes place.

In a preferred embodiment of the invention, the film consists of biaxially oriented polypropylene or biaxially oriented polyester such as polyethylene terephthalate.

The stretch ratio when stretching the film in the longitudinal direction (machine direction), in particular for films made of PE and PP, is preferably from 1:5 to 1:9, particularly preferably from 1:6 to 1:7.5, very particularly preferably from 1:6 to 1: 6.5.

The stretch ratio when stretching the film in the transverse direction (also in particular for films made of PE and PP) is preferably from 1:5 to 1:10, particularly preferably from 1:6 to 1:7.

For PE and PP films it is further preferred when the stretch in machine direction and in transverse direction is the same.

The stretch ratio when stretching the film in the longitudinal direction (machine direction), particularly for films made of PET, is preferably from 1:3.5 to 1:6, particularly preferably from 1:4 to 1: 5.

The stretch ratio when stretching the film in the transverse direction (also in particular for films made of PET) is preferably from 1:3.5 to 1:6, particularly preferably from 1:4 to 1: 5.

For PET films, it is further preferred when the stretch in the machine direction and in the transverse direction is the same.

A stretch ratio of 1:6 means that, for example, a 1m length portion of the film results in a 6m length portion of the stretched film. Draw ratio is often also described as the quotient of the line speed before drawing and the line speed after drawing. The numbers used hereinafter relate to stretching.

The film may also be composed of a blend of polyethylene and polypropylene.

In another advantageous embodiment of the invention, the film comprises at least partially a copolymer of polypropylene (in case of polyethylene as main monomer) or a copolymer of polyethylene (in case of polypropylene as main monomer).

Pure polypropylene or polyethylene is preferred as the film material, but copolymers of ethylene and polar monomers such as styrene, vinyl acetate, methyl methacrylate, butyl acrylate or acrylic acid, which may be homopolymers such as HDPE, L DPE, MDPE, or copolymers of ethylene with another olefin such as propylene, butene, hexene or octene (e.g. LL DPE, V LL DE) polypropylene (e.g. polypropylene homopolymer, polypropylene random copolymer or polypropylene block copolymer) are also suitable.

The proportion of the copolymer (preferably by weight) is always less than the proportion of the main monomers (preferably by weight).

In the most advantageous embodiment of the invention, the film consists of pure polyester, in particular polyethylene terephthalate.

Although limited (deficient), other films, for example made of PA, PU or PVC, are also suitable as carrier materials for adhesive tapes. According to the present invention, none of these polymers is preferred.

Conceivable in the context of the present invention are film laminates wherein at least one film is selected from the group consisting of:

biaxially oriented polypropylene

Biaxially oriented polyethylene or

Biaxially oriented polyesters such as PET.

If the use of the tape requires even greater strength or stretch resistance than can be achieved by the film carrier alone, the carrier can be further reinforced by: fibrous material, in particular individual filaments or filament fabrics or fabrics extending in the machine direction, is attached. The method known to the person skilled in the art comprises applying the fibrous material in question to a pre-coated film web and post-coating with a subsequent, virtually reactive adhesive in a separate (separate) production step or in the same production step.

Variants of the carrier that do not include fibrous materials or other reinforcement means are preferred.

In a further advantageous embodiment, the silk fabric or textile is a warp-knitted fabric with weft inserted (weft inserted warp knit). Such fabrics are described, for example, in EP 1818437 a 1.

The silk or woven fabric preferably has a tensile strength in the machine direction of at least 100N/cm, more preferably 200N/cm, particularly preferably 500N/cm.

The yarn used to produce the fabric or woven preferably has a strength of 80-2200 dtex, preferably 280-1100 dtex.

In the context of the present invention, a filament is understood to mean a bundle of parallel straight individual fibers/individual filaments, often also referred to in the literature as multifilament. Optionally, such a fiber bundle may be consolidated by twisting it, whereupon the filaments are said to be spun or twined. Alternatively, the fiber bundle may be consolidated by rotating using compressed air or water jets. In the following, the general name of silk will be used to refer to all these embodiments.

The filaments may be textured or smooth and may be point consolidated or unconsolidated.

The fabric/weave may be subsequently dyed or may consist of spun-dyed yarns.

It is further preferred when the filaments are made of polyester, polypropylene, polyethylene or polyamide, most preferably polyester (Diolen).

In a further advantageous embodiment of the invention, the number of filaments in the warp direction is at least 6/cm, preferably 10-25/cm, and/or the number of filaments in the weft direction is at least 3-10/cm, preferably 6/cm.

If a filament fabric or textile is provided according to the invention, the applied weight of the adhesive must be selected such that the thickness of the adhesive exceeds the thickness of the filaments by at least 44 μm, preferably more than 50 μm.

When the adhesive is applied, it sinks into the fabric and is therefore unavailable for forming a cohesive force between the adhesive and the substrate.

Sufficient adhesion was achieved only when the thickness of the adhesive exceeded the thickness of the filaments by 44 μm.

It is particularly preferred when the carrier film and thus the adhesive tape according to the invention are not reinforced with individual filaments or filament weaves or fabrics extending in the machine direction.

The film advantageously has a transverse elongation at break of between 20% and 160%, in a particularly advantageous embodiment between 30% and 120%, more preferably between 60% and 100%. Therefore, the transverse elongation at break was also measured in the transverse direction of the film.

The film further advantageously has a thickness of between 15 μm and 150 μm, in a particularly advantageous embodiment between 30 μm and 100 μm, more preferably between 35 μm and 75 μm.

It is further preferable when the film has both elongation at break and thickness within the specified ranges.

The reported values of elongation at break and thickness are particularly suitable for biaxially stretched films.

The carrier preferably consists of exactly one film layer (in addition to auxiliary layers still to be described, such as primers (primers) or release layers).

However, the carrier may comprise one or two or further film layers in addition to one film layer. Embodiments with up to five film layers, which are preferably all formed from the same polymer, particularly preferably polyester, are preferred.

Each of these films may also be made from other polymers or blends of two or more polymers.

In a further advantageous embodiment, the film is opaque.

The carrier may also be coloured.

It is preferred when the carrier is colored by using dyes and/or pigments. If in the following only dyes or pigments are mentioned, it will be clear to the person skilled in the art that both are meant.

Suitable colored pigments are in particular those which are present in finely divided form, for example customary fluorescent and afterglow (nachleuchtende) pigments.

Examples include carbon black, titanium dioxide, calcium carbonate, zinc oxide, silicates or silica, and mica, in particular copper hydrogen phosphate or pearlescent pigments iriodin based on basic lead carbonate. The additive may further be a thermochromic dye.

The pigments may be based on anthraquinones. Anthraquinone dyes are a wide variety of very light-fast dyes of varying constitution, derived from anthraquinones by substitution or by condensation of additional ring systems (e.g., acridone, carbazole, thiazole, thiophene derivatives, oxazines, fused ring systems, etc.).

These include aminoanthraquinone pigments and hydroxyanthraquinone pigments as well as heterocyclic and polycarbocyclic anthraquinone pigments.

The pigments may also consist of azo compounds. All azo dyes have the general formula R1-N ═ N-R2, where the two radicals R1 and R2 can be identical or different.

These dyes are admixed with the base polymer forming the carrier, preferably the carrier film, in particular in the order of a few thousandths (three thousandths) up to not more than 10% by weight, preferably in an amount of 1% to 10% by weight, in particular 2% to 4% by weight, based on the total weight of the carrier layer.

The described film can be used directly as a support for adhesive tapes, wherein the side later coated with adhesive is typically subjected to a fluorine treatment, a plasma treatment, a corona pretreatment or a flame pretreatment in order to better anchor the adhesive to the support.

Fluorine treatment, plasma treatment, corona pretreatment or flame pretreatment may also be used between the back side release agent and the film.

A further improvement in adhesion can be achieved by using a primer (also called adhesion promoter), equivalent to anchoring the adhesive on the support and thus avoiding the transfer of the adhesive to the back side of the support during unwinding of the roll (or as an alternative treatment). Primers which can be used include known dispersion and solvent systems, for example based on isoprene-containing or butadiene-containing rubbers and/or ring rubbers. Isocyanates or epoxy resins as additives improve adhesion and in some cases also increase the shear strength of the pressure-sensitive adhesive. Isocyanate crosslinked primers are preferred.

These make it possible, on the one hand, to achieve targeted adjustment of the surface energy and, on the other hand, to carry out (seek) chemical bonding of the adhesive component to the carrier, for example when using a primer containing isocyanate.

The customary application rates (weight per unit area) of the primers are between 0.01 and 10g/m²Preferably between 0.01 and 3g/m²Between, more preferably between 0.05 and 0.2g/m²In the meantime.

Another option for improving the anchoring is to use a carrier film as follows: which is equipped, in particular by coextrusion, with a polymer surface suitable for connection with pressure-sensitive adhesives.

The adhesive applied to the carrier material is a pressure-sensitive adhesive, i.e. an adhesive which permits permanent bonding to virtually any substrate even under relatively weak contact pressures and which can be detached again from the substrate substantially without residues after use. The pressure-sensitive adhesive has permanent pressure-sensitive adhesion at room temperature, i.e. has a sufficiently low viscosity and a high contact tack, so that it wets the surface of the corresponding adhesive substrate even at low contact pressures. The bondability of an adhesive is based on its adhesive properties and the re-detachability is based on its cohesive properties.

For producing adhesive tapes from a carrier, the pressure-sensitive adhesive is applied in the form of a dry polymer dispersion, wherein the polymer consists of:

(a)95.0 to 100.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

The polymer preferably consists of: 95.0 to 99.5% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate and 0.5 to 5% by weight of an ethylenically unsaturated monomer having an acid or anhydride functional group, more preferably 98.0 to 99.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate and 1.0 to 2.0% by weight of an ethylenically unsaturated monomer having an acid or anhydride functional group.

In addition to the acrylate polymer, the pressure sensitive adhesive may include not only any residual monomers present, but also tackifiers and/or additives set forth below such as light stabilizers or aging stabilizers (in amounts also set forth below).

The pressure-sensitive adhesive is in particular free of further polymers such as elastomers, i.e. the polymers of the pressure-sensitive adhesive consist only of the monomers (a) and (b) in the specified quantitative ratios.

It is preferred when n-butyl acrylate forms monomer (a).

Contemplated monomers (b) advantageously include, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and/or maleic anhydride.

(meth) acrylic acids of the formula I are preferred

Wherein R is³H or CH₃Preferably, mixtures of acrylic or methacrylic acid are optionally used.

Acrylic acid is particularly preferred.

In a particularly preferred variant, the polymer has the following composition:

(a)95.0 to 100.0 wt.%, preferably 95.0 to 99.5 wt.%, more preferably 98.0 to 99.0 wt.% of n-butyl acrylate and

(b)0.0 to 5.0 wt%, preferably 0.5 to 5.0 wt%, more preferably 1.0 to 2.0 wt% of acrylic acid.

A description of this process can be found, for example, in "Emulsion Polymerization and Emulsion polymers" -Wiley-VCH 1997-ISBN 0-471-96746-7 from Peter A. L ovell and Mohamed S.El-Aasser or in EP 1378527B 1.

The following are possible in the polymerization: not all monomers are converted to polymers. It is evident in this connection that the residual monomer content should be as small as possible.

Preferably, an adhesive is provided comprising a polymer dispersion having a residual monomer content of not more than 1 wt.%, in particular not more than 0.5 wt.% (based on the mass of the dried polymer dispersion).

In order to achieve pressure-sensitive adhesive properties, the adhesive must be above its glass transition temperature at the processing temperature to have viscoelastic properties. Since the bonding is carried out at normal ambient temperatures (about 15 ℃ to 25 ℃), the glass transition temperature of the pressure-sensitive adhesive formulation is preferably below +15 ℃ (determined by DSC (differential scanning calorimetry) at a heating rate of 10K/min according to DIN 53765).

The glass transition temperature of the acrylate copolymer can be estimated from the glass transition temperature of the homopolymer and its relative ratio according to the Fox equation.

To achieve a polymer having a desired glass transition temperature, such as a pressure sensitive adhesive or heat seal composition, the quantitative composition of the monomer mixture is advantageously selected to obtain the desired T of the polymer according to equation (G1) analogous to the Fox equation (see T.G.Fox, Bull.am.Phys.Soc.1956,1,123)_GThe value is obtained.

The addition of possible tackifiers inevitably increases the glass transition temperature (by about 5 to 40K depending on the amount added), the compatibility and the softening temperature.

Therefore, acrylate copolymers having a glass transition temperature of not more than 0 ℃ are preferred.

According to the general understanding of the person skilled in the art, a "tackifying resin (adhesive resin)" is understood to mean an oligomeric or polymeric resin as follows: it improves the self-adhesion (tack, inherent tack) of the pressure sensitive adhesive compared to an otherwise identical pressure sensitive adhesive without any tackifying resin.

It is known in principle to use tackifiers to improve the adhesion of pressure-sensitive adhesives. This effect also occurs if up to 15 parts by weight (corresponding to <15 parts by weight) or 5-15 parts by weight of tackifier (based on the mass of the dried polymer dispersion) are added to the adhesive. Preferably 5 to 12 parts by weight, more preferably 6 to 10 parts by weight of tackifier (based on the mass of the dry polymer dispersion) are added.

Suitable tackifiers (also referred to as tackifying resins) include in principle all known substance classes. Tackifiers being, for example, hydrocarbon resins (based, for example, on unsaturated C)₅-or C₉-polymers of monomers), terpene-phenolic resins, polyterpene resins based on starting materials such as α -or β -pinene, aromatic resins such as coumarone-indene resins or resins based on styrene or α -methylstyrene such as rosin and its derivatives such as disproportionated, dimerized or esterified rosin, reaction products for example with diols, glycerol or pentaerythritol, to name a few.

Resins based on terpene-phenols and rosin esters are preferred. Tackifying resins having a softening point above 80 ℃ according to ASTM E28-99(2009) are also preferred. Particularly preferred are terpene-phenol and rosin ester based resins having a softening point above 90 ℃ according to ASTM E28-99 (2009). The resin is advantageously used in the form of a dispersion. This makes them easy to mix in a finely divided manner with the polymer dispersion.

Particular preference is given to variants of the invention in which no tackifying resin is added to the pressure-sensitive adhesive.

Surprisingly and unexpectedly to the skilled person, the absence of tackifying resin in the adhesive tape according to the invention does not result in insufficient adhesion as the skilled person would expect.

Specifically, the following were not added to the pressure-sensitive adhesive:

hydrocarbon treeEsters (e.g. based on unsaturated C)₅-or C₉Polymers of monomers)

Terpene phenolic resin

Polyterpene resins based on starting materials such as α -or β -pinene

Aromatic resins, for example coumarone-indene resins or resins based on styrene or α -methylstyrene, for example rosins and their derivatives, such as disproportionated, dimerized or esterified rosins, for example reaction products with diols, glycerol or pentaerythritol.

The adhesive formulation may optionally be blended with light stabilizers or primary and/or secondary aging stabilizers.

The aging stabilizers used may be products based on sterically hindered phenols, phosphites, thiosynergists, sterically hindered amines or UV absorbers.

It is preferred to use primary antioxidants such as Irganox 1010 or Irganox 254 alone or in combination with secondary antioxidants such as Irgafos TNPP or Irgafos 168.

The aging stabilizers can be used here in any combination with one another, where mixtures of primary and secondary antioxidants in combination with light stabilizers, for example Tinuvin213, exhibit particularly good aging resistance.

It has been found that very particularly advantageous aging stabilizers are those in which the primary antioxidant is combined with the secondary antioxidant in one molecule. These aging stabilizers are the cresol derivatives as follows: the aromatic rings thereof are substituted at any two different positions, preferably ortho and meta to the OH group, by thioalkyl chains, wherein the sulfur atom can also be bonded to the aromatic ring of the cresol unit via one or more alkyl chains. The number of carbon atoms between the aromatic system and the sulphur atom may be between 1 and 10, preferably between 1 and 4. The number of carbon atoms in the alkyl side chain may be between 1 and 25, preferably between 6 and 16. Particular preference is given here to compounds of the 4, 6-bis (dodecylthiomethyl) -o-cresol, 4, 6-bis (undecylthiomethyl) -o-cresol, 4, 6-bis (decylthiomethyl) -o-cresol, 4, 6-bis (nonylthiomethyl) -o-cresol or 4, 6-bis (octylthiomethyl) -o-cresol type. Such aging stabilizers are supplied, for example, by the company Ciba Geigy under the name Irganox 1726 or Irganox 1520.

The amount of aging stabilizer or aging stabilizer package added should be in the range of 0.1 to 10 parts by weight based on the mass of the dried polymer dispersion, preferably in the range of 0.2 to 5 parts by weight based on the mass of the dried polymer dispersion, particularly preferably in the range of 0.5 to 3 parts by weight based on the mass of the dried polymer dispersion.

For particularly simple miscibility with the adhesive dispersion, the dosage form is preferably in the form of a dispersion. Alternatively, the liquid aging stabilizer may also be introduced directly into the dispersion, with a standing time of several hours following the introduction step to allow for uniform distribution in the dispersion or absorption of the aging stabilizer into the dispersion particles. Another alternative is to add an organic solution of the aging stabilizer to the dispersion.

Suitable concentrations are in the range of from 0.1 to 8.0 parts by weight, preferably from 0.1 to 5.0 parts by weight, based on the mass of the dried polymer dispersion.

In order to improve the processing properties, the adhesive formulations can also be blended with customary processing auxiliaries, such as rheological additives (thickeners), defoamers, deaerators, wetting agents or leveling agents. Suitable concentrations are in the range of from 0.1 to 5 parts by weight, based on the mass of the dried polymer dispersion.

A fundamental distinction is made between organic and inorganic rheological additives.

Organic thickeners can then be divided into two main working principles: (i) thickening, i.e., non-association, of the aqueous phase, and (ii) association between thickener molecules and particles, in some cases involving stabilizers (emulsifiers). Representatives of the first substance class (i) are water-soluble polyacrylic acids and copolyacrylic acids, which form polyelectrolytes with a high hydrodynamic volume in the base medium. These are also known to the person skilled in the art as ASE (alkali swellable emulsions). They are characterized by high static shear viscosity and strong shear thinning. Another substance class are modified polysaccharides, in particular cellulose ethers (cellulose ethers) such as carboxymethylcellulose, 2-hydroxyethylcellulose, carboxymethyl-2-hydroxyethylcellulose, methylcellulose, 2-hydroxyethylmethylcellulose, 2-hydroxyethylethylcellulose, 2-hydroxypropylcellulose, 2-hydroxypropylmethylcellulose, 2-hydroxybutylmethylcellulose. This substance class also includes less common polysaccharides such as starch derivatives and special polyethers.

(ii) A working group of associative thickeners is in principle block copolymers with a water-soluble mid-block and a hydrophobic end-block, wherein the end-block interacts with the particle or with itself and thus forms a spatial network involving the particle (including the particle). Typical representatives are well known to the person skilled in the art as follows: HASE (hydrophobically modified alkali swellable emulsion), HEUR (hydrophobically modified ethylene oxide carbamate), or HMHEC (hydrophobically modified hydroxyethyl cellulose). In the case of HASE thickeners, the mid-block is ASE and the end-blocks are typically long hydrophobic alkyl chains connected via polyethylene oxide bridges. In HEUR, the water soluble midblock is polyurethane and in HMHEC the water soluble midblock is 2-hydroxyethyl cellulose. In particular, nonionic HEUR and HMHEC are substantially pH insensitive.

Associative thickeners, depending on the structure, produce more or less newtonian (independent of shear rate) or pseudoplastic (shear-liquification) flow behavior. Occasionally they also exhibit thixotropic properties, i.e. the viscosity is not only dependent on shear forces but also on time.

Inorganic thickeners are generally phyllosilicates of natural or synthetic origin, examples being hectorite and montmorillonite. Upon contact with water, the individual layers separate from each other. At rest, as a result of the different charges on the surface and edges of the chips, they form a space-filling card house structure, resulting in a high static shear viscosity up to the yield point. Upon shearing, the structure of the house collapsed and a significant drop in shear viscosity was observed. Depending on the charge, concentration and geometry of the platelets, the formation of the structure may take some time, so that thixotropy is also obtained with such inorganic thickeners.

The thickener can in some cases be stirred directly into the adhesive dispersion or, in some cases, advantageously pre-dispersed or pre-diluted in water beforehand.

Suppliers of thickeners are, for example, OMG Borchers, Omya, Byk Chemie, Dow chemical company, Evonik, Rockwood, or M ü nzing Chemie.

Fillers (reinforcing or non-reinforcing) such as silica (spherical, acicular, in platelet form or in irregular form, e.g. fumed silica), glass as solid or hollow spheres, microspheres, calcium carbonate, zinc oxide, titanium dioxide, alumina or alumina hydroxide can be used both to adjust the processability and to adjust the adhesive properties. Suitable concentrations are in the range of from 0.1 to 20 parts by weight, based on the mass of the dried polymer dispersion.

However, the substance is not mandatory, the adhesive also functions (works) without adding these individually or in any combination, i.e. without resin and/or other additives.

In a preferred embodiment, the adhesive formulation according to the invention has an adhesion to steel according to astm d3330 of at least 2.0N/cm (about 100g/m on polyester film as support)²Based on the weight of the adhesive).

The coating thickness with respect to the adhesive is preferably in the range of 5 to 250g/m²In particular 15 to 100g/m²More preferably in the range of 50 to 60g/m²Within the range of (1).

The production and processing of the pressure-sensitive adhesives can be carried out from solutions, dispersions or from melts. Preferred production and processing methods are from solutions or dispersions.

The pressure-sensitive adhesive thus produced can then be applied to a support by known methods. Processing from the melt may involve application methods via a nozzle or a calender.

Known solution-based methods include coating using a doctor blade, knife, or nozzle, to name a few.

A backcoat may be applied to the back of the tape to advantageously affect the unwind properties of the tape wound into an archimedean spiral. For this purpose, the back varnish may be provided with a silicone or fluorosilicone compound and with a polyvinylstearyl urethane, a polyethyleneimine stearyl carboxamide or a fluoroorganic compound as release (anti-adhesion) substance. Urethane-based systems are preferred.

Suitable release agents include long chain alkyl based surfactant release systems such as stearyl sulfosuccinate or stearyl sulfosuccinamate; and a polymer selected from the group consisting of polyvinylstearyl carbamate, polyvinylimidostearyl carboxamide, C₁₄-C₂₈Chromium complexes of fatty acids and stearyl copolymers, as described, for example, in DE 2845541A. Release agents based on acrylic polymers with perfluorinated alkyl groups, silicone or fluorosilicone compounds, for example based on poly (dimethylsiloxane), are likewise suitable. It is particularly preferred when the release layer comprises a silicone-based polymer. Particularly preferred examples of such silicone-based release-acting polymers include polyurethane-modified and/or polyurea-modified silicones, preferably organopolysiloxane/polyurea/polyurethane block copolymers, particularly preferably, for example, the anionically stabilized polyurethane-modified and polyurea-modified silicones described in example 19 of EP 1336683B 1, very particularly preferably having a silicone weight fraction of 70% and an acid number of 30mg KOH/g. The use of polyurethane-modified and/or polyurea-modified silicones has the following effects: the product according to the invention combines an optimized aging stability with a universal printability in combination with an optimized peeling behavior. In a preferred embodiment of the invention, the release layer comprises from 10 to 20% by weight, particularly preferably from 13 to 18% by weight, of a release-acting component.

A description of adhesives and release coatings and primers typically used in tapes can be found, for example, in "Handbook of Pressure Sensitive Adhesive Technology" (van Nostrand,1989) by Donatas Satas.

In the context of the present invention, the general expression "adhesive tape" includes all sheet-like structures such as films or film portions (segments) extending in two dimensions, tapes having an extended length and a limited width, tape portions (segments), etc., as well as finally die-cut pieces or labels.

The tape thus has a longitudinal extent (dimension) and a transverse extent. The adhesive tape also has a thickness extending perpendicular to both extents, wherein the lateral and longitudinal extents are multiple times greater than the thickness. The thickness is substantially the same, preferably exactly the same, over the entire area of the tape as defined by the length and width.

The tape is particularly in the form of a web. A web is to be understood as referring to objects as follows: its length is a multiple of the width and the width remains approximately the same, preferably exactly the same, along the entire length.

The adhesive tape can be produced in the form of a roll (i.e. wound onto itself in the form of an archimedes spiral, or covered on the adhesive side with a release material, such as siliconized paper or siliconized film).

Suitable release materials are preferably lint-free materials such as plastic films or fully sized long fiber paper.

The tape has in particular an extension length of 1000-. Typical roll widths are 10, 15, 19, 25 and 30 cm.

A typical construction of an adhesive tape according to the invention is shown in fig. 1.

The product consists of a film (a) and an adhesive (b). In addition, a primer (c) for improving adhesion between the adhesive and the support and a back surface release agent (d) may be used.

The support (a) consists of a membrane support as follows: it has a thickness of between 30 and 55 μm, preferably between 36 and 50 μm, and is made of polyester, such as polyethylene terephthalate.

The adhesive (b) is applied in the form of an acrylate-based dry polymer dispersion, wherein the polymer of the polymer dispersion consists of:

(a)95.0 to 100.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

It is further preferred when the urethane release agent (d) is applied on the side of the open carrier (a) opposite to the adhesive (b).

The present invention describes the following adhesive tapes: it can be used for the hinged connection of panel elements, wherein the tape is applied in such a way that it bridges the gap between the adjacent edges of two panel elements.

The connection is preferably made by: half of the adhesive tape is glued on the edge of the first plate element in such a way that, in terms of the width of the adhesive tape, substantially half of the (self) adhesive remains available for adhesive bonding with the edge of the second plate element. According to this preferred variant, the tapes are applied such that the tapes are arranged on both web ends in as equal portions as possible.

The tape is excellent in absorbing and counteracting lateral/shear forces acting on the tape without stretching of the carrier. This applies in particular to the following cases: the back panel of the cabinet bulges out due to the overfill, so that very large lateral/shear forces act on the adhesive tape.

In its preferred embodiment, the adhesive tape according to the invention may provide further advantages.

The advantage of PET films as a carrier is tear resistance compared to tapes based on e.g. MOPP or BOPP. In the case of MOPP and BOPP, the tear continues in the middle of the tape along the direction of adhesion, while in the case of PET, the tear direction is redirected and leads to the edge. As a result, a large portion of the tape remains intact and secure adhesion is ensured.

Acrylate adhesives provide significantly higher aging stability compared to natural or synthetic rubber adhesives.

The use of acrylic dispersion adhesives has the following advantages: in principle, significantly less residual monomer and/or solvent residues are liberated. This is important for cabinets in living rooms or bedrooms.

The adhesive according to the invention, which is softer than the known adhesives, can produce a cushioning effect with respect to mechanical loads. If the taped cabinet is placed in a hot and humid environment, the wooden back panel absorbs a large amount of water. This results in deformation (bulging) and tensile stress on the tape. If the adhesive tends to be softer, the tape can conform to (follow) the movement of the back panel, while the strongly crosslinked adhesive peels away from the surface.

Furthermore, the adhesives according to the invention have improved tensile behaviour (Aufziehverhalten) and increased initial adhesive strength.

The use of adhesive tapes generally has the following advantages: adhesion is ensured immediately, while the (PU) liquid adhesive must first be cured. This allows a considerable time saving during production.

The invention will be elucidated hereinafter with reference to the drawings without the intention of thereby limiting the invention.

The figures show:

fig. 2 shows the adhesive tape connecting the plate elements.

In fig. 2 is shown an adhesive tape 1 connecting the sheet elements 2, 3. Two plate elements 2, 3 directly adjoining each other are connected by means of an adhesive tape 1 in such a way that the adhesive tape overlaps both edges of the plate elements 2, 3. The plate elements 2, 3 continue "infinitely" to the right and to the left.

The indicated stretching force F acts on the adhesive tape 1 in the transverse direction when folding the panel elements together. The adhesive tape 1, and here in particular the carrier, must be cut to a specific size so that these tensile forces can be absorbed and transmitted without adhesive failure of the adhesive tape 1 and without tearing of the carrier.

The invention is illustrated below by way of examples without the intention to limit the invention thereby.

Example 1 and comparative examples 2 and 3

Respectively using 50g/m²The water-based subsequently dried acrylate adhesive (example 1), the solvent-based subsequently dried acrylate adhesive with the indicated composition (comparative example 2) and the synthetic rubber-based adhesive (comparative example 3) were coated with a 50 μm PET film (Hostaphan RNK 50).

Solvent-based acrylate adhesives:

3% by weight of acrylic acid

10% by weight of methyl acrylate

43.5% by weight of butyl acrylate

43.5% by weight of ethylhexyl acrylate

Based on 30% by weight of polymer of Dertophene T resin (terpene phenolic resin)

A urethane release agent is applied to the film on the side opposite the adhesive.

The water-based acrylate adhesive consisted of 97% by weight of n-butyl acrylate and 3% by weight of acrylic acid.

Pressed MDF boards with a thickness of 3mm were used as wood. The surface quality corresponds to the usual characteristics of MDF boards, for example for cabinet back panels. The surface had a smooth touch with no fibers protruding from the surface.

The following adhesion to wood was measured:

the instantaneous adhesion and the adhesion after stretching were found to be significantly higher than in comparative example (VB) 2. VB3 does exhibit higher instantaneous and tensile adhesion but has two decisive disadvantages: the shear strength at temperatures >40 ℃ (e.g. in the hot zone region) drops significantly. Also the aging stabilizers are significantly worse compared to acrylates.

Comparative example 4 and example 5

Using 50g/m²(thickness corresponding to 50 μm) Water-based acrylate adhesive (example 4) which was subsequently dried, a 50 μm PET film (Hostaphan RNK 50) was coated and 84g/m²(corresponding to a thickness of 84 μm) the water-based acrylate adhesive (example 5) was coated with a 50 μm PET film (Hostaphan RNK 50).

In comparative example 4, a cross-hatched (cross-hatched) fabric made of glass fibers was applied to the membrane before coating with the adhesive, wherein the glass fabric had a basis weight of 39g/m²And a thickness of 40 μm, the number of filaments extending in the longitudinal direction being: the number of filaments 90/dm (measured in the cross direction) and extending in the cross direction was: 25/dm (measured in the longitudinal direction).

The cross-filament fabrics made of glass fibers still have the following disadvantages: in the folding test shown in fig. 3, these were destroyed by breaking of the transverse wires.

The tape from comparative example 4 only achieved 7 folds, whereas example 5 easily withstood more than 10 folds.

Test method

Unless otherwise stated, measurements were made under test conditions of 23 ± 1 ℃ and 50 ± 5% relative air humidity.

Adhesive force

The adhesive force was measured as follows. Wood is used as the prescribed substrate. The adhesive-bondable sheet element to be tested is cut into a width of 20mm and a length of about 25cm, provided with a grip and immediately afterwards pressed 5 times with a 4kg steel roller at an advancement speed of 10 m/min on the respective selected substrate. Immediately thereafter, the bondable sheet-like element was pulled away from the substrate at an angle of 180 ° with a tensile tester (Zwick) and the force required for this was measured at room temperature. The measurement values (in N/cm) were obtained as the average from three separate measurements.

Alternatively, the bonded assembly was stored at 80% relative humidity and 40 ℃ for 3 days, then the bondable sheet-like element was pulled away from the substrate with a tensile tester (Zwick) at an angle of 180 ° and the force required for this was measured at room temperature. The measured values (in N/cm) were again obtained as the average from three separate measurements.

Thickness of

The thickness was measured according to DIN 53370.

Folding test

The folding test is shown in figure 3. In the fold test, a 30cm strip of tape to be tested was affixed to two 3mm thick pressed MDF boards in such a way that it bridged the gap between the adjacent edges, thereby pivoting in the area of the tape.

The two panels are then simultaneously folded by hand through 90 ° in a smooth (flie β enden) motion and the folding process is repeated typically up to 20 times, optionally until the tape peels off or until the tape is broken.

Claims

1. Use of an adhesive tape for the hinged connection of panel elements, wherein the adhesive tape is applied in such a way that it bridges a gap between adjacent edges of two panel elements, wherein

The adhesive tape comprises a carrier made of a film, on one side of which a pressure-sensitive adhesive in the form of an acrylate-based dry polymer dispersion is applied,

the film is a biaxially oriented film made of polypropylene, polyethylene or polyester such as PET,

the polymer of the polymer dispersion consists of:

a)95.0 to 100.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

b)0.0 to 5.0% by weight of an ethylenically unsaturated monomer having acid or anhydride functionality

2. Use of an adhesive tape according to claim 1, characterized in that

A stretch ratio when stretching the film in the machine direction (in particular for films made of PE and PP) of from 1:5 to 1:9, preferably from 1:6 to 1:7.5, particularly preferably from 1:6 to 1:6.5, and/or

The stretch ratio when stretching the film in the transverse direction, in particular for films made of PE and PP, is from 1:5 to 1:10, particularly preferably from 1:6 to 1:7.

3. Use of an adhesive tape according to claim 1, characterized in that

A stretch ratio in stretching the film in the longitudinal direction (machine direction), in particular for films made of PET, of from 1:3.5 to 1:6, preferably from 1:4 to 1:5, and/or

A stretch ratio in stretching the film in the transverse direction (also in particular for films made of PET) of from 3.5 to 1:6, preferably from 1:4 to 1:5, and/or

The stretch ratios in the machine direction and in the transverse direction when stretching the film (in particular for films made of PET) are the same.

4. Use of an adhesive tape according to at least one of claims 1 to 3, characterized in that

The adhesive tape comprises a film carrier having a thickness of between 30 and 55 μm, preferably between 36 and 50 μm.

5. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The film is made of pure polyester, such as PET.

6. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

An adhesion promoter is applied between the carrier and the adhesive layer.

7. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The polymer is composed of:

(a)95.0 to 99.5% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

(b)0.5 to 5.0% by weight of an ethylenically unsaturated monomer having acid or anhydride functionality.

8. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The polymer is composed of:

(a)98.0 to 99.0% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate

(b)1.0 to 2.0 wt% of an ethylenically unsaturated monomer having acid or anhydride functionality.

9. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

N-butyl acrylate forms monomer (a).

10. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

Acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and/or maleic anhydride, preferably acrylic acid or methacrylic acid or a mixture of both, form monomer (b).

11. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

Up to 15 parts by weight or 5 to 15 parts by weight of tackifier (based on the mass of the dry polymer dispersion), preferably 5 to 12 parts by weight, more preferably 6 to 10 parts by weight tackifier (based on the mass of the dry polymer dispersion) are added to the adhesive.

12. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

No tackifier resin is added to the pressure sensitive adhesive.

13. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The glass transition temperature of the pressure-sensitive adhesive is below +15 ℃ (determined by DSC (differential scanning calorimetry) at a heating rate of 10K/min according to DIN 53765).

14. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The tape is applied to the inside of the fold formed when the panel elements are folded together.

15. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The fiber board, in particular a hard fiber board, a particle board, an MDF or HDF board, particularly preferably an MDF board, forms the board element.

16. Use of an adhesive tape according to at least one of the preceding claims, characterized in that

The plate element forms a cabinet back panel.