WO2019110498A1

WO2019110498A1 - Use of an adhesive strip for connecting panel elements in an articulated manner

Info

Publication number: WO2019110498A1
Application number: PCT/EP2018/083334
Authority: WO
Inventors: Stephan BERNT
Original assignee: Tesa Se
Priority date: 2017-12-04
Filing date: 2018-12-03
Publication date: 2019-06-13
Also published as: CN111433304A; EP3720919A1; DE102017221759B3

Abstract

The invention relates to the use of an adhesive strip for connecting panel elements in an articulated manner. The adhesive strip is adhered so as to bridge the gap between adjacent edges of two panel elements, wherein the adhesive strip has a carrier which is made of a film and on one side of which an adhesive compound in the form of a dried acrylate-based 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 is made of: c) 95.0 to 100.0 wt.% n-butyl acrylate and/or 2-ethylhexyl acrylate and d) 0.0 to 5.0 wt.% of an ethylenically unsaturated monomer with an acid or acid anhydride function; and a release layer is provided on the carrier side not coated with the adhesive compound, in particular a carbamate-based release layer.

Description

description

Use of an adhesive tape for the articulated connection of plate elements

The invention relates to the use of an adhesive tape for the articulated connection of plate elements, wherein the adhesive tape is bonded in such a way that it bridges the gap between the adjacent edges of two plate elements such that the pivot axis lies in the region of the adhesive tape.

Plate elements, preferably fiberboard, are known from the prior art, which are used, for example, as cabinet rear walls for entrainment furniture. These are by means of separate fasteners, for example grooved plastic rails, wherein the plate elements are inserted into the grooves, connected to each other and fixed to the back of a cabinet.

Foldable panels play an important role as an element of entrained furniture, in particular cupboard furniture. They have significant advantages over the use of two individual plates as the back wall, since they form a dust-tight joint and can not move against each other when tensile or shear forces occur. A foldable rear wall can be folded by folding the plate elements to half the area size and can be packed in this way relatively space-saving.

Foldable plates of this type consist for example of hardboard, chipboard, MDF or HDF boards.

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

• 80 to 83 percent wood

• 9 to 10.5 percent glue

• 0.5 to 2.5 percent additives and • 6 to 8 percent water.

The plates have, for example, a Gutseite, which is coated with plastic or painted and which should be in the assembled furniture to the interior of this piece of furniture, and a more or less unprocessed back. The Faltbarkeit has the additional advantage that the plate elements can be stacked with the Gutseiten so that they are protected during handling, packaging and transport against damage.

The fiber boards are at least partially connected along a connecting edge by an adhesive preferably based on polyurethane or an adhesive strip. Due to this design, both plate elements form a unit, which are designed foldable. In the region of the adhesive strip results in a pivot axis about which the two plate elements can be folded or pivoted.

Among other things, single-sided adhesive tapes are used to join the panel elements.

One-sided adhesive tapes are glued in half to one edge of the first panel element in such a way that essentially half of the self-adhesive composition, seen in the width of the adhesive tape, is available for bonding to the edge of the second panel element. Advantageously, the single-sided adhesive tapes are provided with a centrally slit release or cover paper, so that the bonds can be carried out successively, wherein only a portion of the release paper is removed in each case. The adhesive tape sections are preferably applied by machine.

In order to be able to absorb high tensile forces, adhesive tapes based on glass filament layers are used. When using adhesive tapes with Glasfilamentgelegen there is a risk that the filaments break during the folding of the back walls and eliminates the stabilizing effect.

From WO 2005/052438 A2 a foldable plate with at least two plate elements is known, which are connected by an adhesive layer along mutually adjacent connecting edges with rectangular profile hinged together, so that the plate elements are foldable about an axis, wherein the plate elements in the folded state lie flush with each other with their connecting edges and the adhesive layer is at least partially adhered to the joint edges of the respective plate elements. The adhesive-coated joint edges abut each other in the unfolded state of the plate elements. As the adhesive layer, a curing polyurethane elastic adhesive is proposed.

Due to the process, the PU adhesive has the disadvantage that the job has to be ensured exactly between the two rear wall halves. Very precise work is a must here. Furthermore, liquid adhesives must always cure for a while until they develop their full performance. Adhesive tapes do not have this disadvantage. Using tapes can save a lot of time (and money in a mass business). Furthermore, the bonding sites are not as strong as the bond with an adhesive tape.

For the articulation of plate elements filament tapes are used, ie adhesive tapes in which the carrier is reinforced with a scrim or fabric of filaments, in particular glass filaments. These have the disadvantage that in a folding of the back walls and the tape is folded. Due to this "buckling load" of the adhesive tape, the glass fibers break through and thus offer no reinforcement.

Adhesive tapes based on synthetic rubber adhesives can ensure a high instantaneous adhesion which hardly increases or decreases even during climate storage (the bond strength tends to decrease here). However, these adhesives are not as resistant to aging as acrylate adhesives.

The object of the invention is to provide an adhesive tape for the articulated connection of plate elements which has all the necessary mechanical properties in order to be able to be used in particular under high loads.

This object is achieved by the use of an adhesive tape, as characterized in more detail in the main claim. Advantageous embodiments of the invention are described in the subclaims. Accordingly, the invention relates to the use of an adhesive tape for the articulated connection of plate elements, wherein the adhesive tape is glued so that it bridges the gap between adjacent edges of two plate elements, wherein

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

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

The polymer of the polymer dispersion is composed 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 an acid or acid anhydride function

And there is a release layer on the non-adhesive coated side of the backing, especially based on carbamate.

The adhesive tape is thus glued so that it bridges the gap between the adjacent edges of two plate elements so that the pivot axis is in the region of the adhesive tape.

For three (or more) panel members to be joined, the panels may be folded in zig-zag folding (also known as fanfold folding), in wrap folding, or in window folding (also known as box folding (according to a triptych)). It is preferred that the one or more adhesive tapes are always applied to the inside of the resulting fold in order to avoid overstretching of the carrier when folding as possible.

Further preferably, fibreboards form the plate elements, in particular hardboard, chipboard, MDF or HDF boards. Particularly preferred are MDF boards.

According to a particularly advantageous variant of the invention, the plate elements form a cabinet rear wall, wherein the one or more folds in the cabinet rear wall can be arranged horizontally, vertically and both horizontally and vertically. Due to the special mechanical requirements, oriented film carriers are used for the adhesive tape. By orienting the extension of the primary film formed primarily in the production process in one or more preferred directions, the mechanical properties can be selectively influenced. So-called biaxially oriented films can be stretched either sequentially, wherein the primary film after formation by extrusion with a slot die is first stretched in the machine direction by being passed over a sequence of rollers, wherein the transport speed of the film is greater than the speed at the exit from the extrusion nozzle. Subsequently, the film is stretched in a drafting device in the transverse direction. The stretching of the film in two directions can also be carried out in one step (see for example US 4,675,582 A and US 5,072,493 A).

It is also known to draw BOPP support in the blown film process.

The principle of the orientation lies in the alignment of the polymer molecule chains and the crystal structures formed therefrom as well as in the orientation of the amorphous regions in certain preferred directions and the associated increase in strength. Due to the principle, but also the strength in the direction in which is not oriented, reduced.

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

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

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

Further preferably, stretching in the longitudinal direction and transverse direction is the same for PE and PP films.

The stretch ratio in the stretching of the film (in particular in the case of films made of PET) in the longitudinal direction (machine direction) is preferably 1: 3.5 to 1: 6, particularly preferably 1: 4 to 1: 5. The stretch ratio in the stretching of the film (also in particular in the case of films made of PET) in the transverse direction is preferably 1: 3.5 to 1: 6, particularly preferably 1: 4 to 1: 5. Further preferably, the stretching in the longitudinal direction and transverse direction is the same for PET films.

A stretch ratio of 1: 6 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. Often, the draw ratio is also referred to as the quotient of the line speed before drawing and the line speed after drawing. The numbers used below refer to the stretching.

Furthermore, the film may consist of blends of polyethylene and polypropylene.

According to a further advantageous embodiment of the invention, the film contains at least partially copolymers of the polypropylene (in the case of polyethylene as the main monomer) or copolymers of the polyethylene (in the case of polypropylene as the main monomer).

As the sheet material, pure polypropylene or polyethylene is preferable, but copolymers of ethylene and polar monomers such as styrene, vinyl acetate, methyl methacrylate, butyl acrylate or acrylic acid are also included. It may be a homopolymer such as HDPE, LDPE, MDPE or a copolymer of ethylene with another olefin such as propene, butene, hexene or octene (for example LLDPE, VLLDE). Also suitable are polypropylenes (for example polypropylene homopolymers, polypropylene random copolymers or polypropylene block copolymers).

The (preferably by weight) proportion of the copolymer is always smaller than the (preferably by weight) proportion of the main monomer.

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

Also suitable as a carrier material for the adhesive tape, but rather insufficiently continue to be films such as, for example, PA, PU or PVC. All of these polymers are not preferred according to the invention.

Conceivable in the context of the invention are film laminates in which at least one film is selected from the group • biaxially oriented polypropylene

Biaxially oriented polyethylene or

• biaxially oriented polyester such as PET.

If the use of the adhesive tape requires even greater strength or stretch resistance than can be achieved by a single film backing, the backing may be further reinforced by the addition of fibrous materials, particularly individual MD or filament fabrics or plies. Known to those skilled in the art are the application of mentioned fibrous materials on a precoated film web and running in a separate or even in the same production step post-coating with the later actually effective adhesive.

Preferably, the variant of the carrier, which has no fibrous materials or other reinforcing measures.

According to a further advantageous embodiment, the filament fabric or fabric is a warp knit fabric with weft threads (weft inserted warp knit). Such is described, for example, in EP 1 818 437 A1.

The filament web or web has a machine direction tensile strength of preferably at least 100 N / cm, more preferably 200 N / cm, most preferably 500 N / cm.

Preferably, the yarns used to form the fabric or fabric have a thickness of 80 to 2200 dtex, preferably 280 to 1 100 dtex.

For the purposes of this invention, a filament is understood to mean a bundle of parallel, straight individual fibers / single filament, often referred to in the literature as multifilament. Optionally, this fiber bundle can be solidified by twisting, then one speaks of spun or twisted filaments. Alternatively, the fiber bundle can be solidified by swirling with compressed air or water jet. In the following, for the sake of generality, only the term filament is used for all these embodiments.

The filament can be textured or smooth and point-solidified or unconsolidated. The scrim may be subsequently dyed or spun yarns.

More preferably, the filaments consist of polyester, polypropylene, polyethylene or polyamide, preferably polyester (diols).

According to a further advantageous embodiment of the invention, the filament count in the warp direction is at least 6 / cm, preferably 10 to 25 / cm and / or the filament count in the weft at least 3 to 10 / cm, preferably 6 / cm.

If a filament fabric or scrim is provided according to the invention, the application weight of the adhesive must be selected so that the thickness of the adhesive projects beyond the thickness of the filament by at least 44 μm, preferably by more than 50 μm. When the adhesive is applied, it sinks in the scrim and is therefore not available for the formation of cohesive forces between the adhesive and the substrate.

Only when the thickness of the adhesive exceeds the thickness of the filament by 44 μm, sufficient bonding forces are achieved.

It is particularly preferred if the carrier film and thus the adhesive tape according to the invention are not reinforced with individual MD yarns or filament webs or plies.

Advantageously, the films have an elongation at break in the transverse direction between 20% and 160%, in a particularly advantageous embodiment between 30% and 120%, more preferably between 60% and 100%. The elongation at break in the transverse direction is determined accordingly in the transverse direction of the film.

Further advantageously, the films have a thickness between 15 pm and 150 pm, in a particularly advantageous embodiment between 30 pm and 100 pm, more preferably 35 pm and 75 pm.

More preferably, the films simultaneously have an elongation at break and a thickness which are within the specified limits.

The values given for the elongation at break and the thickness apply in particular to biaxially stretched films. Preferably, the carrier consists of exactly one film layer (in addition to the auxiliary layers to be described, such as primer or release).

However, in addition to a film layer, the carrier may have one or two or more film layers. Preference is given to embodiments with up to five film layers, which are preferably all formed from the same polymer, particularly preferably polyester.

Each of these films can also consist of other polymers or blends of two or more polymers.

According to a further advantageous embodiment, the film is opaque.

Furthermore, the carrier may be colored.

Preferably, the carrier is colored by the use of dyes and / or pigments. If, in the following, only dyes or pigments are mentioned, then it is obvious to a person skilled in the art that both are meant.

Suitable color pigments are, in particular, those which are finely distributed, for example general purpose, fluorescent and luminescent pigments.

Examples are carbon black, titanium dioxide, calcium carbonate, zinc carbonate, zinc oxide, silicates or silica, and also mica, especially copper hydroxide phosphate or else iriodin, a pearlescent pigment based on basic lead carbonate. Furthermore, the additive may be a thermochromic dye.

The pigment can be based on anthraquinone. Anthraquinone dyes are an extensive group of very lightfast dyes of various constitution which are derived from anthraquinone by substitution or by condensation of other ring systems (for example acridones, carbazoles, thiazoles, thiophene derivatives, azines, fused ring systems and the like).

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

Further, the pigment may consist of an azo compound. All azo dyes have the general formula R 1 -N = N-R 2, where the two radicals R 1 and R 2 may be identical or different. These dyes are the carrier, preferably the carrier film-forming base polymers in particular of the order of a few parts per thousand (from 3 parts per thousand) to a maximum of 10 wt .-%, preferably in amounts of 1 to 10 wt .-%, in particular from 2 to 4 wt .-% based on the total weight of the carrier layer, mixed.

As a carrier for the adhesive tape, the films described can be used directly, usually a fluorine, a plasma treatment corona or flame pretreatment of later to be coated with the adhesive side to anchor the adhesive better on the support.

A fluorine, a plasma treatment, a corona or even flame pretreatment can also be used between the reverse side release and the film.

A further improvement of the adhesion equivalent to the anchoring of the adhesive on the carrier and thus avoiding the transfer of adhesive to the back of the carrier during unwinding of the rolls (or as an alternative treatment) can be achieved by the use of primers (also called adhesion promoter). As primers, the known dispersion and solvent systems can be used, for example based on isoprene- or butadiene-containing rubbers and / or cyclo rubbers. Isocyanates or epoxy resins as additives improve the adhesion and in part also increase the shear strength of the pressure-sensitive adhesive. Preference is given to isocyanate-crosslinked primers.

With these, on the one hand, the surface energy can be adjusted in a targeted manner and, on the other hand, for example, when using isocyanate-containing primers, a chemical attachment of the adhesive component to the carrier can be pursued.

The usual surface application weight of the primer is between 0.01 and 10 g / m ² , preferably between 0.01 and 3 g / m ² , more preferably between 0.05 and 0.2 g / m ² .

Another way to improve the anchoring, is the use of carrier films, which are equipped by coextrusion specifically with a favorable for the connection to the pressure-sensitive adhesive polymer surface.

The adhesive applied to the carrier material is a pressure-sensitive adhesive, that is to say an adhesive which, even under relatively slight pressure, allows a permanent connection with almost all adhesive reasons and, after use, essentially free from residue Haftgrund can be replaced again. A PSA is permanently tacky at room temperature, so it has a sufficiently low viscosity and high tack, so that it wets the surface of the respective Klebegrunds already at low pressure. The adhesiveness of the adhesive is based on its adhesive properties and the removability on their cohesive properties.

In order to produce an adhesive tape from the support, a pressure-sensitive adhesive is applied in the form of a dried polymer dispersion, the polymer being composed of:

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

Preferably, the polymer 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 acid anhydride function, more preferably 98 , 0 to 99.0 wt .-% of n-butyl acrylate and / or 2-ethylhexyl acrylate and 1, 0 to 2.0 wt .-% of an ethylenically unsaturated monomer having an acid or acid anhydride function.

In addition to the acrylate polymers listed, in addition to any residual monomers which may be present, the tackifier and / or additives such as light stabilizers or aging inhibitors mentioned below may additionally be added in the quantities also mentioned below.

In particular, no further polymers such as elastomers are contained in the pressure-sensitive adhesive, that is to say that the polymers of the pressure-sensitive adhesive consist only of the monomers (a) and (b) in the stated proportions.

Preferably, n-butyl acrylate forms the monomer (a).

Suitable monomers (b) are, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and / or maleic anhydride.

Preference is given to (meth) acrylic acid of the formula I,

wherein R ³ = H or CH ₃ , preferably the mixture of acrylic acid or methacrylic acid is preferably used. Particularly preferred is acrylic acid.

According to 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 .-% acrylic acid

The polymer dispersion is prepared by the process of emulsion polymerization of said components. Descriptions of this process can be found, for example, in "Emulsion Polymerization and Emulsion Polymers" by Peter A. Lovell and Mohamed S. El-Aasser - Wiley-VCH 1997 - ISBN 0-471 -96746-7 or in EP 1 378 527 B1.

During the polymerization, it can not be ruled out that not all monomers are converted into polymers. It is obvious that the residual monomer content should be as small as possible.

Adhesives are preferably provided comprising the polymer dispersion having a residual monomer content of less than or equal to 1% by weight, in particular less than or equal to 0.5% by weight (based on the mass of the dried polymer dispersion).

To achieve tacky properties, the adhesive must be at the processing temperature above its glass transition temperature to have viscoelastic properties. Since the bonding takes place at normal ambient temperature (approximately between 15 ° C to 25 ° C), the glass transition temperature of the PSA formulation is preferably below +15 ° C (determined by DSC (differential scanning calorimetry) according to DIN 53 765 at a heating rate of 10 K. / min). The glass transition temperature of the acrylate copolymers can be estimated according to the equation of Fox from the glass transition temperatures of the homopolymers and their relative proportions).

In order to obtain polymers, for example PSAs or heat sealants, with desired glass transition temperatures, the quantitative composition of the monomer mixture is advantageously chosen such that according to equation (G1) in analogy to the Fox equation (cf. TG Fox, Bull. Am. Phys. Soc. 1956, 1, 123) gives the desired T _G value for the polymer.

(G1)

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

Therefore, acrylate copolymers having a glass transition temperature of at most 0 ° C. are preferred.

By "adhesive resin" is meant, according to the general understanding of the art, an oligomeric or polymeric resin which increases the autoadhesion (tack, inherent tack) of the pressure-sensitive adhesive compared to the otherwise non-adhesive-containing, otherwise identical pressure-sensitive adhesive.

The use of tackifiers to increase the bond strengths of PSAs is basically known. This effect also occurs when the adhesive is added up to 15 parts by weight (corresponding to <15 parts by weight), or from 5 to 15 parts by weight of tackifier (based on the mass of the dried polymer dispersion). Preferably, 5 to 12, more preferably 6 to 10 parts by weight of tackifier (based on the mass of the dried polymer dispersion) are added.

In principle, all known substance classes are suitable as tackifiers, also referred to as tackifier resins. Tackifiers are, for example, hydrocarbon resins (for example polymers based on unsaturated Cs or Cg monomers), terpene-phenolic resins, polyterpene resins based on raw materials such as α- or β-pinene, aromatic resins such as cumarone-indene resins or styrene-based or a-methylstyrene as Rosin and its derivatives, for example disproportionated, dimerized or esterified rosin, for example reaction products with glycol, glycerol or pentaerythritol, to name just a few. Preference is given to resins without readily oxidizable double bonds, such as terpene-phenolic resins, aromatic resins and particularly preferably resins which are prepared by hydrogenation, for example hydrogenated aromatic resins, hydrogenated polycyclopentadiene resins, hydrogenated rosin derivatives or hydrogenated polyterpene resins.

Preference is given to resins based on terpene phenols and rosin esters. Also preferred are tackifier resins having a softening point above 80 ° C according to ASTM E28-99 (2009). Particular preference is given to resins based on terpene phenols and rosin esters having a softening point above 90 ° C. according to ASTM E28-99 (2009). The resins are expediently used in dispersion form. They can be mixed so easily with the polymer dispersion finely divided.

Particularly preferred is the variant of the invention in which no adhesive resins are added to the PSA.

Surprisingly and unpredictably for a person skilled in the art, the lack of adhesive resins in the adhesive tape according to the invention does not lead-as the person skilled in the art would expect-to an insufficient bond strength.

In particular, the following substances are not added to the PSA:

Hydrocarbon resins (for example polymers based on unsaturated Cs or Cg monomers)

• terpene phenolic resins

• Polyterpene resins based on raw materials such as a- or ß-pinene

Aromatic resins such as coumarone-indene resins or styrene-based or a-methylstyrene-based resins such as rosin and its derivatives, for example disproportionated, dimerized or esterified rosin, for example reaction products with glycol, glycerol or pentaerythritol

The adhesive formulation may optionally be blended with sunscreens or primary and / or secondary anti-aging agents.

As anti-aging agents, products based on sterically hindered phenols, phosphites, thiosynergists, sterically hindered amines or UV absorbers can be used. Preferably used are primary antioxidants such as Irganox 1010 or Irganox 254, alone or in combination with secondary antioxidants such as Irgafos TNPP or Irgafos 168.

The anti-aging agents can be used in any combination with each other, with mixtures of primary and secondary antioxidants in combination with light stabilizers such as Tinuvin 213 show particularly good aging protection.

Anti-aging agents have proven particularly advantageous in which a primary antioxidant is combined with a secondary antioxidant in one molecule. These antioxidants are cresol derivatives whose aromatic ring is substituted with thioalkyl chains at any two different positions, preferably in the ortho and meta position relative to the OH group, the sulfur atom also having one or more alkyl chains on the aromatic ring of the cresol component can be connected. The number of carbon atoms between the aromatic and the sulfur atom may be between 1 and 10, preferably between 1 and 4. The number of carbon atoms of the alkyl side chain may be between 1 and 25, preferably between 6 and 16. Particular preference is given to compounds of the type 4,6-bis (dodecylthiomethyl) -o-cresol, 4,6-bis (undecylthiomethyl) -o-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol.

Bis (decylthiomethyl) -o-cresol 4,6-bis (nonylthiomethyl) -o-cresol or 4,6-bis (octylthiomethyl) -o-cresol. Such anti-aging agents are offered for example by the company Ciba Geigy under the name Irganox 1726 or Irganox 1520.

The amount of the anti-aging agent or aging inhibitor package added should be in a range between 0.1 and 10 parts by weight, based on the mass of the dried polymer dispersion, preferably in a range between 0.2 and 5 parts by weight, based on the mass of the dried polymer dispersion, more preferably in one range between 0.5 and 3 parts by weight based on the mass of the dried polymer dispersion.

The dosage form is preferably in the form of a dispersion for particularly easy miscibility with the adhesive mass dispersion. Alternatively, liquid aging inhibitors can also be incorporated directly into the dispersion, wherein the incorporation step should be followed by a service life of a few hours to homogenous distribution in the dispersion or the inclusion of the anti-aging agent to allow in the dispersion particles. Another alternative is the addition of an organic solution of the anti-aging agents in the dispersion.

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

To improve the processing properties, the adhesive composition may also be blended with conventional processing aids such as rheology additives (thickeners), defoamers, deaerators, wetting agents or leveling agents. Suitable concentrations are in the range of 0.1 to 5 parts by weight, based on the mass of the dried polymer dispersion.

Basically, a distinction is made between organic and inorganic rheology additives.

The organic thickeners, in turn, split into two main principles of action: (i) the thickening of the aqueous phase, ie, not associating, and (ii) associative formation between thickener molecule and particles, in part involving the stabilizers (emulsifiers). Representatives of the first (i) group of substances are water-soluble polyacrylic acids and polycoacrylic acids which form polyelectrolytes with a large hydrodynamic volume in the basic medium. The person skilled in the art also refers to these as ASE (alkali swellable emulsion). They are characterized by high perturbation viscosities and severe shear thinning. Another class of substances are the modified polysaccharides, in particular cellulose ethers such as carboxymethylcellulose, 2-hydroxyethylcellulose, carboxymethyl-2-hydroxyethylcellulose, methylcellulose, 2-hydroxyethylmethylcellulose, 2-hydroxyethylethylcellulose, 2-hydroxypropylcellulose, 2-hydroxypropylmethylcellulose, 2-hydroxybutylmethylcellulose. In addition, less widely used polysaccharides such as starch derivatives and special polyethers belong to this class of substances.

The active group of (ii) associative thickeners are, in principle, block copolymers having a water-soluble middle block and hydrophobic end blocks, the end blocks interacting with the particles or themselves, thereby forming a space network incorporating the particles. Typical representatives are familiar to the skilled person as HASE (hydrophobically modified alkali-swellable emulsion), HEUR (hydrophobically modified ethylene oxides urethane) or HMHEC (hydrophobically modified hydroxyethyl cellulose). In the case of the HASE thickeners, the middle block is an ASE; the end blocks are mostly long, hydrophobic alkyl chains coupled via polyethylene oxide bridges. At the HEUR is the water-soluble middle block is a polyurethane, in HMHEC a 2-hydroxyethylcellulose. Especially the non-ionic HEUR and HMHEC are largely insensitive to pH.

Depending on the structure, the associative thickeners cause more or less Newtonian (shear rate independent) or pseudoplastic (shear fluidizing) flow behavior. Sometimes they also show a thixotropic character, that is, they show not only a shear force dependence of the viscosity but also a time dependence.

The inorganic thickeners are mostly phyllosilicates of natural or synthetic origin, examples are hectorites and smectites. In contact with water, the individual layers separate from each other. Through different charges on surfaces and edges of the platelets, they form a space-filling house structure in peace, resulting in high quiescent viscosities up to yield points. When shearing collapses the house structure and there is a significant drop in shear viscosity observed. Depending on the charge, concentration and geometric dimensions of the platelets, the structural structure may take some time, so thixotropy can also be achieved with such inorganic thickeners.

Some of the thickeners can be stirred directly into the adhesive dispersion or, in some cases, advantageously prediluted or predispersed in water.

Suppliers of thickeners include OMG Borchers, Omya, Byk Chemie, Dow Chemical Company, Evonik, Rockwood or Münzing Chemie.

Fillers (reinforcing or non-reinforcing), such as silicas (spherical, needle-shaped, platelet-shaped or irregular, such as pyrogenic silicas), glass as solid or hollow spheres, microballoons, calcium carbonates, zinc oxides, titanium dioxides, aluminum oxides or aluminum oxide hydroxides can be used to adjust the processability as well as the serve adhesive properties. Suitable concentrations are in the range of 0.1 to 20 parts by weight, based on the weight of the dried polymer dispersion.

The enumerated substances are in turn not mandatory, the adhesive also works without these added individually or in any combination, ie without resins and / or residual additives. In a preferred embodiment, the adhesive composition of the invention according to ASTM D3330 has a bond strength to steel of at least 2.0 N / cm (with a weight per unit area of the adhesive of about 100 g / m ² on polyester film as support).

The coating thickness with adhesive is preferably in the range from 5 to 250 g / m ² , in particular from 15 to 100 g / m ² , more preferably in the range from 50 to 60 g / m ² .

The preparation and processing of the PSAs can be carried out from solution, dispersion and from the melt. Preferred production and processing methods are carried out from solution or dispersion.

The pressure-sensitive adhesives prepared in this way can then be applied to the carrier by the generally known methods. When processed from the melt, these can be application methods via a nozzle or a calender.

In solution processes, coatings with doctor blades, knives or nozzles are known, to name just a few.

On the back of the adhesive tape, a backside lacquer can be applied to favorably influence the unwinding properties of the adhesive tape wound on the Archimedean spiral. This backcoat can be equipped with silicone or fluorosilicone compounds as well as polyvinyl stearyl carbamate, Polyethyleniminstearylcarbamid or fluoroorganic compounds as abhesive (anti-adhesive) acting substances. Preferred is a carbamate based system.

Suitable release agents include surfactant release systems based on long chain alkyl groups such as stearyl sulfosuccinates or stearyl sulfosuccinamates, as well as polymers which may be selected from the group consisting of polyvinyl stearyl carbamates, polyethyleneimine stearyl carbamides, chromium complexes of CM to C28 fatty acids and stearyl copolymers such as in DE 28 45 541 A are described. Also suitable are release agents based on acrylic polymers with perfluorinated alkyl groups, silicones or fluorosilicone compounds, for example based on poly (dimethyl-siloxanes). Most preferably, the release layer comprises a silicone-based polymer. Particularly preferred examples of such silicone-based release polymers include polyurethane- and / or polyurea-modified silicones, preferably organopolysiloxane / polyurea / polyurethane block copolymers, particularly preferred are those described in Example 19 of EP 1 336 683 B1, very particularly preferably anionically stabilized polyurethane- and urea-modified silicones having a silicone weight fraction of 70% and an acid number of 30 mg KOH / g. The use of polyurethane and / or urea-modified silicones causes the effect that the products according to the invention have an optimized separation behavior with optimized aging resistance and universal compatibility. In a preferred embodiment of the invention, the release layer comprises 10 to 20% by weight, particularly preferably 13 to 18% by weight, of the release-active constituent.

Descriptions of the adhesives commonly used for adhesive tapes and release lacquers and primers are found, for example, in Donatas Satas' "Handbook of Pressure Sensitive Adhesive Technology" (van Nostrand, 1989).

For the purposes of this invention, the general term "adhesive tape" encompasses all flat structures such as films or film sections which are expanded in two dimensions, tapes of extended length and limited width, strip sections and the like, and ultimately also diecuts or labels.

The adhesive tape thus has a longitudinal extent and a width extent. The adhesive tape also has a thickness extending perpendicular to both expansions, wherein the width dimension and longitudinal extent are many times greater than the thickness. The thickness is as equal as possible, preferably exactly the same, over the entire areal extent of the adhesive tape determined by the length and width.

The adhesive tape is in particular in web form. Under a track is understood to be an object whose length is many times greater than the width and the width along the entire length in approximately preferably exactly the same formed.

The adhesive tape can be rolled up on itself in the form of a roll, that is to say in the form of an Archimedean spiral, and can also be produced with adhesive materials such as siliconized paper or siliconized film.

As a release material is preferably a non-fluffing material such as a plastic film or a well-glued, long-fiber paper. The adhesive tapes have in particular run lengths of 1000 to 30,000 m. The width of the rolls is usually 10, 15, 19, 25 and 30 cm.

FIG. 1 shows a typical structure of the adhesive tape according to the invention.

The product consists of a film (a) and an adhesive (b). In addition, it is also possible to use a primer (c) for improving the adhesion between the adhesive and the backing and a reverse side release (d).

The carrier (a) consists of a film carrier with a thickness between 30 and 55 pm, preferably 36 and 50 pm of polyester such as polyethylene terephthalate.

The pressure-sensitive adhesive (b) is applied in the form of a dried polymer dispersion based on acrylate, the polymer of the polymer dispersion being composed of:

a) 95.0 to 100.0 wt .-% n-butyl acrylate and / or 2-ethylhexyl acrylate

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

Further preferably, a carbamate release (d) is applied to the open carrier side (a) opposite the adhesive (b).

The invention describes an adhesive tape, which can be used for the articulated connection of plate elements, wherein the adhesive tape is bonded in such a way that it bridges the gap between adjacent edges of two plate elements.

The bonding preferably takes place in that the adhesive tape is glued in half over the edge of the first panel element in such a way that substantially half of the (self) adhesive, seen in the width of the adhesive tape, is available for bonding to the edge of the second panel element. The adhesive tape is glued according to this preferred variant so that the adhesive tape rests on equal parts as possible on the two web ends.

The adhesive tape is excellently able to absorb and counteract the transverse / shear forces acting on the adhesive tape without the wearer stretching. This is especially true in the case when the rear wall of the cabinet due to a strong filling of the same outwardly bulges, so that very large transverse / shear forces act on the tape. The adhesive tape according to the invention in its preferred embodiment can come up with further advantages.

An advantage of a PET film as a carrier over adhesive tapes, which are based for example on MOPP or BOPP, is the tearability. While in MOPP and BOPP a crack continues along the bonding direction in the center of the adhesive tape, in PET the tear direction is diverted and led to the edge. As a result, a large part of the adhesive tape remains intact and secure bonding is guaranteed.

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

The use of acrylate dispersion adhesives has the advantage, in principle, of significantly less residual monomers and / or solvent residues. This is essential for cabinets in living rooms or bedrooms.

By the adhesive according to the invention, which is softer compared to the known, a kind of buffer effect for mechanical loads can occur. If a cabinet glued to the adhesive tape is placed in a humid environment, the wooden back wall absorbs a large amount of water. This leads to a deformation (buckling) and a tensile load on the tape. Now, if the adhesive tends to be softer, the adhesive tape can go along with a movement of the back wall, whereas highly crosslinked adhesives chip off the surface.

Furthermore, the adhesive properties of the inventive adhesive improve the build-up behavior and increase the initial bond strength.

The use of an adhesive tape generally offers the advantage that bonding can be ensured immediately, whereas (PU) liquid adhesives still have to harden. This can save a lot of time during production.

In the following, the invention will be explained in more detail with reference to a figure, without intending to cause any restriction whatsoever. It shows

Figure 2 shows the adhesive tape in the connection of plate elements.

In the figure 2, the adhesive tape 1 in the connection of plate elements 2, 3 is shown. For this purpose, two plate elements 2, 3, which abut directly, connected by means of the adhesive tape 1 such that the adhesive tape overlaps both edges of the plate elements 2, 3. The plate elements 2, 3 continue left to left or right "endless" away.

When folding the plate elements act on the adhesive tape 1, the tensile forces F shown in the transverse direction. The adhesive tape 1, and here in particular the carrier, must be dimensioned so that these tensile forces can be absorbed and transmitted without the adhesive tape 1 failing adhesively and without the wearer being torn.

In the following, the invention is explained in more detail by examples, without wishing to restrict the invention.

Example 1 and Comparative Examples 2 and 3

On a 50 μm PET film (Hostaphan RNK 50), in each case at 50 g / m ^2, a water-based acrylate adhesive is applied, which is then dried (Example 1), applied to a solvent-based acrylate adhesive with the stated composition, which is subsequently dried ( Comparative Example 2) and a synthetic rubber-based adhesive (Comparative Example 3) applied.

Solvent based acrylate adhesive:

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 the polymer weight 30% by weight of resin Dertophene T (terpene phenolic resin) On the side opposite the adhesive side of the film, a carbamate release is applied.

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

The wood used is a pressed MDF board of 3 mm thickness. The surface quality corresponds to the usual nature of MDF boards, as they are used for cabinet back walls. The surface is haptically smooth, no chips protrude from the surface.

The following bond strengths on wood are measured:

It can be seen that an instantaneous bond strength and the bond strength after being applied to the comparison example (VB) 2 are significantly higher. Although the VB3 shows a higher instant and Aufzieh sticking force, but has two major disadvantages: The shear strength at temperatures> 40 ° C (for example, in tropical areas) decreases dramatically. Furthermore, the aging resistance to acrylates is significantly worse. Comparative Example 4 and Example 5

On a 50 pm PET film (Hostaphan RNK 50) is applied with 50 g / m ² (equivalent to a thickness of 50 pm) a water-based acrylate adhesive, which is then dried (Comparative Example 4), and on a 50 pm PET film (Hostaphan RNK 50) is water-based at 84 g / m ² (equivalent to a thickness of 84 pm)

Acrylic adhesive (Example 5) applied. In Comparative Example 4, a cross-filament scrim of glass fibers is applied to the film prior to coating with adhesive, the basis weight of the glass fabric being 39 g / m ² and the thickness being 40 pm, the number of longitudinal filaments being 90 / dm (measured in the transverse direction ) and the number of transverse filaments: 25 / dm (measured in the longitudinal direction.

If a filament fabric or scrim is provided according to the invention, the application weight of the adhesive must be selected so that the thickness of the adhesive projects beyond the thickness of the filament by at least 44 μm, preferably by more than 50 μm.

A disadvantage of Crossfilamentgelegen of glass fibers is further that they are destroyed in the folding test shown in Figure 3 by breaking the transverse filaments.

The adhesive tape of Comparative Example 4 achieves only seven folds, while Example 5 can easily survive more than ten folds.

Test Methods

The measurements are (unless otherwise stated) at a test climate of 23 ± 1 ° C and 50 ± 5% rel. Humidity carried out. adhesive power

The determination of the bond strength was carried out as follows. Wood was used as a defined primer. The glued surface element to be examined was cut to a width of 20 mm and a length of about 25 cm, provided with a handling section and immediately thereafter pressed five times with a steel roller of 4 kg at a feed rate of 10 m / min on the selected primer. Immediately thereafter, the glued surface element was removed at an angle of 180 ° from the primer with a tensile tester (Zwick) and measured the force required for this at room temperature. The measured value (in N / cm) was the average of three individual measurements.

Alternatively, the bonding for three days at 80% rel. F. and stored 40 ° C before the glued surface element at an angle of 180 ° from the primer with a tensile tester (Zwick) withdrawn and measured the force required for room temperature. The measured value (in N / cm) again averaged out of three individual measurements.

thickness

The thickness is measured according to DIN 53370.

folding test

FIG. 3 shows the folding test. In the folding test, a 30 cm long strip of the tape to be tested is glued to two pressed 3 mm thick MDF board so that it bridges the gap between the adjacent edges so that the pivot axis lies in the region of the adhesive tape.

Subsequently, the two plates are folded simultaneously in a flowing movement by 90 ° at a time, and the folding operations are counted, usually up to twenty times, if necessary, until the adhesive tape is detached or until the adhesive tape is damaged.

Claims

claims

1. Use of an adhesive tape for the articulated connection of plate elements, wherein the adhesive tape is glued so that it bridges the gap between adjacent edges of two plate elements, wherein

the polymer of the polymer dispersion is composed of:

a) 95.0 to 100.0 wt .-% n-butyl acrylate and / or 2-ethylhexyl acrylate

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

and on the non-adhesive coated side of the carrier a release layer is present, in particular based on carbamate.

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

characterized in that

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

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

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

characterized in that

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

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

the stretching ratio in the stretching of the film (in particular in the case of films made of PET) is the same in the longitudinal direction and in the transverse direction.

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

the adhesive tape has a film carrier with a thickness between 30 and 55 μm, preferably 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

between the carrier and the adhesive layer, a bonding agent is applied.

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 an acid or acid anhydride function

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% by weight of an ethylenically unsaturated monomer having an acid or acid anhydride function

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 forming the monomer (b), preferably acrylic acid or methacrylic acid or the mixture of both.

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

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

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

no adhesive resins are 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 PSA below +15 ° C (determined by DSC (Differential Scanning Calorimetry) according to DIN 53 765 at a heating rate of 10 K / min).

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

the adhesive tape is applied to the inside of the fold resulting from the folding of the plate elements.

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

Fiberboard forming the plate elements, in particular hardboard, chipboard, MDF or HDF boards, particularly preferably MDF boards.

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

the plate elements form a cabinet rear wall.