DE102019220524A1 - Process for cutting thin polymer glass laminate - Google Patents

Abstract

With a method for cutting a polymer-thin-glass laminate, wherein the polymer-thin-glass laminate consists of at least one layer of a polymer with a thickness of less than 500 microns and at least one glass layer with a thickness of 250 microns or less, in which the Thin glass is cut by means of a mechanical cutting process and the polymer is cut by means of a laser cutting process, polymer-thin-glass laminate sections with good edge strength are obtained. In addition, processability in a roll-to-roll method is made possible.

Description

The present invention relates to a method for cutting a polymer-thin-glass laminate, the polymer-thin-glass laminate consisting of at least one layer of a polymer with a thickness of less than 500 μm and at least one glass layer with a thickness of 250 μm or less.

For a number of years, research has been carried out on processes that make it possible to separate thin glass, i.e. glass with a thickness of <250 µm, and in particular polymer-thin-glass laminates, into polymer-thin-glass sections. In the case of polymer-thin-glass laminates, the problem arises that, due to the different properties of polymer and thin glass, known separation processes are sufficiently suitable either only for the polymer or for the thin glass.

• Das Ritz-Brech-Verfahren, bei dem Dünnglas zunächst angeritzt und anschließend durch Brechen oder Ziehen getrennt wird, ist generell bekannt und genutzt. Es ist z.B. in der WO 2013/050166 A1 beschrieben. Mit diesem Verfahren lassen sich komplexe Geometrien erzeugen, und die Kantenfestigkeit ist hoch. Das Ergebnis des Schneidprozesses ist eine Schnittkante, die eine geringe Rauheit sowie eine gute Kantenstabilität aufweist. Allerdings lassen sich mit diesem Verfahren keine Glas-Polymer-Laminate trennen.

Known cutting processes for thin glass can be used in mechanical cutting processes (scratch-breaking process, blade cutting process), laser cutting processes (stress crack cutting, CO laser cutting, laser ablation with ultra-short pulse lasers, laser perforation / laser filament cutting) and etching processes (chemical cutting, selective laser etching) subdivide. These are briefly explained below:

• The scratch-breaking process, in which thin glass is first scratched and then separated by breaking or pulling, is generally known and used. For example, it is in the WO 2013/050166 A1 described. Complex geometries can be produced with this method and the edge strength is high. The result of the cutting process is a cut edge that has a low roughness and good edge stability. However, this process cannot be used to separate glass-polymer laminates.

Polymer materials can be separated with the help of knives and / or scissors in the so-called blade cutting process. Thin glass, on the other hand, cannot be separated by using knives or scissors in such a way that good edge strength and a smooth edge surface can be achieved.

Polymeric materials can also be separated using abrasive mechanical processes such as sawing, milling or water jet cutting. These methods cannot be used for thin glass either due to the inadequate edge quality that can be achieved.

Single-stage mechanical cutting processes are therefore either suitable for cutting thin glass or polymer, but not both materials in one laminate, since the cutting tools required are unsuitable for the other material.

Laser cutting processes are usually suitable for cutting glass and polymer. The widely used CO ₂ laser is well suited for polymers, but often leads to destruction due to the high energy input into glass. There are therefore a multitude of refined methods for cutting glass using lasers.

With stress crack cutting (Engl .: Laser Scribing), as it is eg in the DE 69304194 T2 is described, a part of the surface is locally heated with the aid of a laser, which works in the infrared or UV range, and then suddenly cooled with the aid of a cooling medium. The result is a vertical and splinter-free break. In addition, the resulting edge has a high level of strength. However, stress crack cutting is not reliably suitable for small radii, for more complex geometries, for glasses with a thickness of less than 200 µm and also not for polymers.

Carbon monoxide lasers (CO lasers) are generally suitable for cutting glass, as glass has a high level of absorption in certain wavelength ranges that can be easily covered by CO lasers. However, when cutting with a CO laser, there is what is known as “threading” on glass, which means that the cut edge is not clean. In addition, this process is only used for glasses with a thickness well over 250 µm.

In the case of ablation using ultra-short pulse laser radiation (laser ablation with ultra-short pulse lasers), the energy is focused on the surface of the material in the form of ultra-short pulses in or below the picosecond range, with the material being absorbed by the laser energy (multi-photons Effect) is rapidly heated and the material evaporates. The material or the laser is guided over the component once or several times, depending on the thickness of the material, in order to remove layer by layer until the glass is isolated. The process is suitable for cutting complex geometries from glass as well as polymers, but the glass edge shows scale-like structures (chipping), which greatly reduce their strength.

Laser nano-perforation (also laser filament cutting) is a method in which an ultra-short pulse laser (wavelengths in the picosecond or femtosecond range) creates many µm-wide channels into the glass or right through it are arranged in a line. This is done by forming a laser filament Achieved, which is either formed by an adapted laser optics (Bessel beam, multi-pass focusing) or is formed by using the Kerr self-focusing effect. The latter cannot be used with thin glasses with a thickness of less than 250 µm. Due to thermal or mechanical stress, the glass breaks along this line due to the previous weakening of the material.

In the case of a polymer-glass laminate that is to be separated using this process, only the glass is perforated and separated. The applied polymer is not completely severed and can only be separated by tearing and / or pulling on the separated glass. This leads to undefined shapes on the polymer edge.

The chemical etching processes are generally suitable for cutting glass and creating complex geometries from thin glass. The glass is pretreated before the actual etching process, whereby the geometry of the finished product is determined. Such a process is generally conceivable for polymers, but has not been tested.

Metal assisted chemical etching (MaCE) is referred to as chemical cutting. The component is provided with a precious metal at the points where the material is to be removed. In the presence of an oxidizing agent (e.g. hydrogen peroxide) in an acidic environment (e.g. hydrogen fluoride), the material is oxidized and removed at the areas covered with precious metal. The disadvantage of such a process is that it takes place very slowly compared to the processes mentioned above and is more difficult to control due to the use of chemicals. There is also the possibility of degradation or loss of function of the polymer in a laminate through interaction with hydrogen fluoride.

Chemical cutting can be accelerated by using a heating wire. Here, phosphoric acid is placed on the glass along the geometry to be cut and the wire is heated to 200 ° C at this point (Hot Wire Phosphoric Acid Cutting). Although this process is faster than MaCE, it is still very slow compared to other cutting processes. In addition, when using the wire, a straight cut edge cannot be guaranteed, which means that the glass loses edge stability. Furthermore, there is also the risk of interactions between acid and polymer with this method.

With Selective Laser Etching (SLE), the material to be cut is modified with a laser in such a way that it can be chemically etched. To do this, the focus of an ultra-short pulse laser is moved through the material with a pulse duration in the femtosecond range, so that channels with a diameter larger than 1 µm are created. At these points, the etching is up to 500 times faster than at unmodified points on the component. After the laser treatment, the component is placed in a bath with an etching liquid (e.g. hydrogen fluoride). There the modified material is removed by etching. Complex geometries can be created in the component and a high level of precision can be achieved during the etching process. The disadvantage is that this method can only be used for transparent materials and any coatings (polymers) are also removed by the etching liquid. In addition, the SLE is a slow process due to the need for a separate etching bath, since no in-line process is possible and the etching is the time-limiting factor.

From the methods described above, the laser perforation method emerges as a good possibility to separate thin glass without chipping and glass breakage, or to extract complex geometries from a glass sheet. The edge strength of the cut edge of the thin glass in such processes is, however, below 150 MPa, which is well below the requirement profile for many applications. In addition, there is no known cutting method for a thin glass-polymer laminate that can be reliably used for in-line processing on a production line.

For laser cutting of polymeric materials in combination with thin glass, laser ablation with an ultra-short pulse laser is most likely to come into question, since the process can in principle be used for both materials. However, in terms of the edge properties of the glass, results that are satisfactory for the requirement are not achieved.

The object of the present invention was therefore to provide an improved method for cutting thin polymer glass laminates. In particular, the method is intended to ensure reliable bendability of the thin glass laminate without the formation of cracks emanating from the cut edge. Furthermore, the polymer should show only slight decomposition phenomena at the cut edge, i.e. not be degraded and thus impaired in its function.

This object is achieved by a method as described in the independent claim. The subclaims relate to advantageous developments of the subject matter of the invention. The invention also includes a polymer thin glass laminate and its use.

Accordingly, the invention relates to a method of the type mentioned at the beginning for cutting a polymer thin glass laminate, in which thin glass is cut by means of a mechanical cutting process and the polymer is cut by means of a laser cutting process.

Surprisingly, it has been found that the combination of a mechanical cutting process and a laser cutting process produces clean cuts and very stable cut edges. The processes do not have a negative impact on one another. The invention fulfills both the requirements for a separation process for thin polymer glass laminates with good edge strength and the requirements for processability in a roll-to-roll process. A roll-to-roll process is understood to mean a process in which both the two laminate layers, that is, thin glass and polymer, are in roll form and, after lamination in the laminate, are also rewound into a roll. For example, in a roll-to-roll process, a wide roll is trimmed at the edges or cut into several narrow rolls.

In principle, various methods are available as cutting methods for the polymer, namely in particular cutting with scissors or a knife, water jet cutting, ablative laser beam cutting and etching. According to the invention, the polymer is cut by means of an ablative laser cutting process.

The following processes are particularly suitable for cutting thin glass: water jet cutting, scribing-breaking processes (e.g. with diamond scribing), selective laser etching (SLE), stress crack cutting, ablative laser beam cutting, laser perforation (possibly with subsequent breaking), chemical cutting (e.g. with HF ), Sandblast cutting, blade dicing or ultrasonic cutting. According to the invention, the thin glass is cut by means of a scratch-breaking process.

The respective methods have already been described in detail above, to which reference is made here.

Surprisingly, the combination of the scratch-breaking process for glass and an ablative laser cutting process for the polymer is particularly well suited to solving the problem. The two processes can be carried out at different times in any order or at the same time. In particular, it has surprisingly been found that the scratch-breaking process for the glass layer of the laminate leads to the severing of the glass layer even if the polymer layer has not yet been severed.

A thin glass is a glass and a thin glass film web is a film with a thickness of 10 to 250 μm, preferably 20 to 100 μm, preferably 25 to 75 μm, particularly preferably 30 to 50 μm. The entire thin glass film web is preferably formed from thin glass. Thin glass films are very suitable as substrates to block permeation. Thin glass are available for example as D263 or AF32 by Schott or Willow ^® Glass Corning.

An alkali-containing thin glass such as D263 T eco is advantageous because the coefficient of thermal expansion is higher and better matches the polymeric components of an organic electronic arrangement, e.g. an OLED structure.

Such thin glasses can be used in the down-draw process, as in the WO 00/41978 A1 is described, or in processes such as those described in, for example EP 1 832 558 A1 are disclosed. The first-mentioned document discloses further processes for producing composites from thin glass and polymer layers or films.

The thickness of the thin glass is generally from 5 to 250 μm, preferably from 10 to 150 μm, particularly preferably from 20 to 80 μm, since a particularly high flexibility is given here, more preferably from 50 to 120 μm, since in this thickness range there is a high flexibility is paired with sufficient stability. A thickness of 30 to 75 µm is very particularly preferred.

According to the invention, the thickness of the polymer is 2 to 500 μm, preferably less than 200 μm, since a particularly high degree of flexibility is achieved in this way. The thickness is particularly preferably more than 10 μm, since sufficient stability of the polymer layer is thus obtained. With a polymer thickness of less than 2 µm, the polymer film is usually so fragile that it breaks apart after the glass is separated, making a further cutting process unnecessary.

The thickness of thin glass and polymer can be the same or different. The thickness of the polymer is preferably less than that of the thin glass, since this facilitates roll winding of the composite with the inner glass film due to the higher elasticity of the polymer layer. If the thin glass is to be wound on the outside of a roll, it is preferred to make the polymer layer thicker than the thin glass, since the tendency for creases to form in the polymer layer is then reduced.

A polymer in the context of the present invention is a chemical compound that is usually made up of organic chain or branched Molecules (macromolecule) that consist of the same, similar or different units (the so-called monomers). In the simplest case, the macromolecule consists of only one type of monomer. Copolymers are made up of various monomers that are randomly distributed in the macromolecule, regularly distributed or can be present in blocks. Polymers contain at least three identical monomer units. For the purposes of this definition, a monomer unit is the bound form of a monomer in a polymer.

The polymer can be of a linear, branched, star-shaped or grafted structure, to give just a few examples, and be constructed as a homopolymer, a random copolymer, an alternating or block copolymer. For the purposes of this invention, the term “statistical copolymer” includes not only those copolymers in which the comonomers used in the polymerization are incorporated purely randomly, but also those in which gradients in the comonomer composition and / or local enrichment of individual comonomer types occur in the polymer chains . Individual polymer blocks can be built up as a copolymer block (random or alternating).

Examples of polymers are elastomers such as are customarily used in the field of pressure-sensitive adhesives, as described, for example, in the “Handbook of Pressure Sensitive Adhesive Technology” by Donatas Satas (Satas & Associates, Warwick 1999).

These are, for example, elastomers based on acrylates and / or methacrylates, polyurethanes, natural rubbers, synthetic rubbers such as butyl, (iso) butyl, nitrile or butadiene rubbers, styrene block copolymers with an elastomer block made of unsaturated or partially or fully hydrogenated polydiene blocks (polybutadiene, Polyisoprene, poly (iso) butylene, copolymers of these and other elastomer blocks known to those skilled in the art), polyolefins, fluoropolymers and / or silicones.

If rubber or synthetic rubber or blends produced from them are used as polymers, then the natural rubber can basically be made from all available qualities such as crepe, RSS, ADS, TSR or CV types, depending on the required purity and viscosity level, and synthetic rubber or synthetic rubbers from the group of randomly copolymerized styrene-butadiene rubbers (SBR), butadiene rubbers (BR), synthetic polyisoprenes (IR), butyl rubbers (IIR), halogenated butyl rubbers (XIIR) ), the acrylate rubbers (ACM), the ethylene vinyl acetate copolymers (EVA) or the polyurethanes and / or their blends.

Any type of thermoplastic known to the person skilled in the art can also be used as the polymer, as is described, for example, in the textbooks "Chemistry and Physics of Synthetic Polymers" by J.M.G. Cowie (Vieweg, Braunschweig) and “Macromolecular Chemistry” by B. Tieke (VCH Weinheim, 1997) are mentioned.

Preferred polymers are polyolefins such as polyethylene (PE) or polypropylene (PP), cyclic olefin copolymers (COC), polyvinyl chloride (PVC), polyester - especially polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polymethylpentene (PMP), ethylene vinyl alcohol (EVOH) , Polyvinylidene chloride (PVDC), fluoropolymers such as polyvinylidene fluoride (PVDF), polycarbonate (PC), polyamide (PA), polyethersulfone (PES), polyetherimide (PEI), polyarylate (PAR), cellulose triacetate (TAC), polymethacrylate (PMMA) or polyimide (PI).

In a preferred embodiment, the at least one polymer layer is a pressure-sensitive adhesive.

According to the invention, a “pressure-sensitive adhesive” is understood, as is generally customary, to mean a substance which - in particular at room temperature - is permanently tacky and also tacky. It is characteristic of a pressure-sensitive adhesive that it can be applied to a substrate by pressure and remains adhered there, the pressure to be applied and the duration of this pressure being not defined in more detail. In some cases, depending on the exact type of pressure-sensitive adhesive, the temperature and humidity as well as the substrate, the application of a short-term, minimal pressure, which does not go beyond a light touch for a brief moment, is enough to achieve the adhesive effect, in others In some cases, a long-term exposure to high pressure may be necessary.

Pressure-sensitive adhesives have special, characteristic viscoelastic properties that lead to permanent tack and adhesiveness. They are characterized by the fact that when they are mechanically deformed, both viscous flow processes and the build-up of elastic restoring forces occur. Both processes are related to one another in terms of their respective proportions, depending on the exact composition, structure and degree of crosslinking of the pressure-sensitive adhesive as well as on the speed and duration of the deformation and on the temperature.

The proportionate viscous flow is necessary to achieve adhesion. Only the viscous parts, caused by macromolecules with relative great mobility, enable good wetting and flow onto the substrate to be bonded. A high proportion of viscous flow leads to high pressure-sensitive tack (also referred to as tack or surface tack) and thus often also to high bond strength. Strongly cross-linked systems, crystalline or glass-like solidified polymers are generally not or at least only slightly tacky due to the lack of flowable components.

The proportional elastic restoring forces are necessary to achieve cohesion. They are caused, for example, by very long-chain and strongly tangled macromolecules, as well as by physically or chemically cross-linked macromolecules, and enable the forces acting on an adhesive bond to be transmitted. They lead to the fact that an adhesive connection can withstand a permanent load acting on it, for example in the form of permanent shear stress, to a sufficient extent over a longer period of time.

The storage modulus (G ') and loss modulus (G' ') that can be determined using dynamic mechanical analysis (DMA) can be used for a more precise description and quantification of the degree of elastic and viscous components as well as the relationship between the components. G 'is a measure of the elastic part, G' 'is a measure of the viscous part of a substance. Both sizes are dependent on the deformation frequency and the temperature.

The sizes can be determined with the aid of a rheometer. The material to be examined is exposed to a sinusoidally oscillating shear stress, for example in a plate-plate arrangement. In devices controlled by shear stress, the deformation is measured as a function of time and the time offset of this deformation with respect to the introduction of the shear stress. This time offset is referred to as the phase angle δ.

The storage modulus G 'is defined as follows: G' = (τ / γ) · cos (δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between shear stress and deformation vector). The definition of the loss modulus G '' is: G '' = (τ / γ) · sin (δ) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between the shear stress and deformation vector).

A substance is generally considered to be pressure-sensitive adhesive and is defined as pressure-sensitive adhesive within the meaning of the invention if at room temperature, here by definition at 23 ° C, in the deformation frequency range from 10 ° to 10 ¹ rad / sec G 'at least partially in the range from 10 ³ to 10 ⁷ Pa and if G ″ is also at least partly in this range. “Partly” means that at least a section of the G 'curve lies within the window that is defined by the deformation frequency range from 10 ° up to and including 10 ¹ rad / sec (abscissa) and the range of G 'values from 10 ³ up to and including 10 ⁷ Pa (ordinate). This applies accordingly to G''.

All pressure-sensitive adhesives known to the person skilled in the art can be used as the pressure-sensitive adhesive, for example those based on acrylates and / or methacrylates, polyurethanes, natural rubbers, synthetic rubbers, styrene block copolymer compositions with an elastomer block composed of unsaturated or hydrogenated polydiene blocks (polybutadiene, polyisoprene, copolymers of both and others, elastomer blocks familiar to those skilled in the art), polyolefins, fluoropolymers and / or silicones. This also includes other materials that have pressure-sensitive adhesive properties in accordance with the “Handbook of Pressure Sensitive Adhesive Technology” by Donatas Satas (Satas & Associates, Warwick 1999).

Preferred PSAs are those which, based on a thickness of 50 μm, have a WVTR of less than 100 g / m ² d. When using such pressure-sensitive adhesives, the laminate is particularly suitable for encapsulating structures sensitive to water vapor permeation.

The water vapor permeation rate (WVTR) is measured at 38 ° C. and 90% relative humidity according to ASTM F-1249, the oxygen permeation rate (OTR) at 23 ° C. and 50% relative humidity according to DIN 53380 part 3.

Preferred pressure-sensitive adhesives are likewise those which, based on a thickness of 50 μm, have a transmission of more than 90% and a haze of less than 2%, since a laminate with such a pressure-sensitive adhesive is particularly suitable for optical applications.

The transmission of the adhesive layer is determined analogously to ASTM D1003-11 (Procedure A (Hazemeter Byk Haze-Gard Dual), standard illuminant D65). A correction of interface reflection losses is not made.

The HAZE value (also known as the haze value) describes the portion of the transmitted light that is scattered at a large angle towards the front by the irradiated layer. The haze value thus quantifies structures in the surface or in the volume that interfere with the clear view. The method for measuring the haze value is also described in the ASTM D 1003-11 standard. The standard requires the measurement of four transmission measurements. For each transmission measurement, the Calculated light transmittance. The four degrees of transmission are offset against the percentage haze value. The haze value is measured with a Haze-Gard Dual from Byk-Gardner GmbH.

A borosilicate glass, such as the D263 T eco from Schott, an alkali earth alkali silicate glass or an aluminum borosilicate glass such as AF 32 eco, also from Schott, is advantageously used for the thin glass film composite web according to the invention. An alkali-free thin glass such as AF 32 eco is advantageous because the UV transmission is higher. For UV-curing adhesive systems, initiators with absorption maxima in the UV-C range can therefore be better used, which increases the stability of the uncrosslinked adhesives with respect to daylight.

The scribing-breaking process comprises two process steps, on the one hand scribing and on the other hand breaking that follows the scribing. The scratching is preferably carried out by means of a diamond, but other processes are also possible that work, for example, with hard metal wheels or laser ablation (ultrashort pulse laser). The breaking can be done mechanically, for example by folding or pulling apart. Breaking is particularly preferably brought about by thermal stress, for example by directing a laser beam onto the thin glass for heating and then cooling it.

In a preferred embodiment, the thermal stress is introduced with the same laser beam that is also used for the ablative laser cutting of the polymer. Polymer removal and thin glass breaking can take place in two successive steps. It is particularly advantageous for the two steps to take place simultaneously, i.e. in one step and with the same laser beam, on the one hand, the polymer is removed and, on the other hand, thermal stress is applied to the scratches in the thin glass. Depending on which side the laser beam is applied from, it strikes - preferably - first on the polymer and then on the thin glass or - vice versa - first on the thin glass and then on the polymer. The prerequisite for this procedure is that the thin glass has already been scored. If the polymer is removed before the scratching and the breaking is to take place by means of thermal stress introduced by a laser beam, the necessary step sequence is polymer removal - scratching of the thin glass - breaking of the thin glass by means of thermal stress.

In the method according to the invention, the wavelength of the laser is particularly preferably selected such that the laser beam used for ablative laser cutting is at least partially absorbed by the thin glass. This enables the double use of the laser beam as described above for polymer removal and thin glass breaking.

The wavelength of the laser is usually selected so that the laser radiation is absorbed by the polymer. This can be promoted by additives in the polymer such as carbon black.

The wavelength of the laser can be selected in such a way that it is at least partially absorbed by the glass, which is analogous, for example, in the case of an absorption ASTM D1003-11 (Procedure B, standard illuminant D65), is given by more than 20%, or that it is essentially transmitted by the glass, which is for example measured analogously with a transmission ASTM D1003-11 (Procedure B, standard illuminant D65), is given by more than 80%.

It is preferably selected such that it is essentially transmitted by the glass in order to avoid damage to the glass.

Basically, laser beams can be divided into focused and unfocused laser beams. For the preferred embodiment of the method according to the invention, the focused laser beam is preferred, but this does not mean that the invention is restricted to this.

The focused laser beam subsides DIN EN ISO 11145 characterize by parameters. The most important parameters for describing the laser beam are the diameter of the beam waist D _{o, u} and the Rayleigh _{length z R} , which result from the focal length of the focusing optics and the beam quality of the laser beam. The location of the beam waist is called the laser focus.

The term focus position Δz is understood to mean the position of the laser focus in the beam direction relative to the component. The point of impact Δx describes the location at which the laser beam hits the component. Together, the two parameters characterize the distribution of the laser beam power on the component.

In order to control the energy supplied to the thin glass or the polymer, it is useful to adjust the focus position of the laser beam. The focus can be outside the laminate, in the thin glass film, in the polymer layer or in the interface between the two layers. It is irrelevant which layer of the laminate is facing the laser beam source. It is an advantageous embodiment of the method to introduce the laser beam on the glass side, but to select the wavelength and focus position so that the polymer layer is removed from the surface of the laminate opposite the beam source.

The focus is preferably in the polymer layer, since this achieves high ablation efficiency.

In the method according to the invention, the scratching for separating the thin glass is preferably carried out first using the scratch-breaking method and then the ablative laser beam cutting for removing the polymer. This has the advantage that the thermal energy introduced during the laser beam cutting of the polymer induces stresses in the thin glass, which can be used to widen the mechanically made scratching into a crack that cuts through the glass, e.g. by subsequent cooling of the glass side of the laminate. The mechanical loading of the scratch required during mechanical cutting to achieve a severing of the glass can be significantly reduced or it can even be dispensed with. In this case it is further preferred if the wavelength of the laser is selected such that it is at least partially absorbed by the glass.

In this case, it is further preferred if the focus of the laser lies in the interface between thin glass film and polymer or in the thin glass film, since a more focused heat input into the glass is achieved, which facilitates crack propagation.

Furthermore, both processes can be carried out from the same side of the laminate or from different sides. Carrying out from different sides is preferred.

If both processes are carried out from the same side and from the polymer-coated side, it is preferred that the laser cutting process is carried out first and then the scratch-breaking process. This has the advantage that the polymer is removed first and the scratch for the scratch-crushing process is recorded directly on the glass surface.

If both processes are carried out from the same side and from the glass side, it is preferred to carry out the scratch-breaking process first and then the laser cutting process. If the scribing-crushing process initially only performs scribing, this opens up the possibility of using the gas pressure created by the polymer degradation during laser cutting at the glass-polymer interface as a source of mechanical energy for the breaking.

If both processes are carried out from different sides, it is preferred that the scratching and breaking process is carried out from the glass side and the laser cutting process is carried out from the polymer-coated side. It is preferred here that the scratch-breaking process is carried out first and then the laser process. This has the advantage that the severed glass film sections are initially held in their position by the polymer layer, which simplifies handling.

The trace of the laser ablation (cutting line) in polymer cutting is characterized by a width that is dependent on the process and the process parameters and within which the polymer is ablated. In contrast to this, mechanical glass cutting only induces a crack in the material that has no width. The scratch line of the glass section is usually within the vertical projection of the track of the polymer removal into the plane of the glass section. The person skilled in the art is inclined to place the line of the glass cut in the middle of the corresponding track of the polymer removal in order to obtain increased process reliability. This is known as a symmetrical cut. The disadvantage here is that the edge of the thin glass and polymer cannot be flush with the cut, but rather the thin glass extends beyond the polymer on both sides of the cut. There may be applications in which such a "protrusion" of the thin glass is desired, e.g. if edges are to be closed that are present on the complementary part to which the polymer-thin glass laminate is to be connected. In most cases, however, such an offset should not be desired.

For the purposes of the present invention, it is therefore preferred to guide the line of the glass section asymmetrically outside the center of the vertical projection of the track of the polymer removal into the plane of the glass section. This makes it possible to place the glass cut close to the edge of the track of the polymer removal and thus to minimize the area of the thin glass in the cut-out body that is no longer covered with polymer after the cutting process.

In a further preferred embodiment, the line of the glass section is guided outside the vertical projection of the track of the polymer removal. The distance to the edge of the projection of the track is less than 1 mm, preferably less than 0.3 mm. This ensures complete coverage of the cut-out glass sheet with the polymer layer.

It is particularly preferred to arrange two glass sections each asymmetrically within the vertical projection of the track of the polymer removal. This makes it possible to minimize the edge not covered with polymer at the same time for two flat structures resulting from the cutting process.

In a preferred embodiment, both cuts are made from the same side. This can be implemented more easily in terms of production technology; in particular, turning the sensitive laminate can be dispensed with. In another suitable embodiment, the two glass cuts are made from different sides.

The cutting of the polymer and the glass are preferably carried out from different sides. This particularly facilitates the asymmetrical cut.

The invention also relates to a thin polymer glass laminate section which can be obtained by the method according to the invention. Depending on the size and shape of the laminate, the section can be produced by one cut using the method according to the invention or several cuts using the method according to the invention. “One cut” means the overall cut, combined from mechanical cutting of the glass and laser cutting of the polymer. The method according to the invention can also be combined with other methods not according to the invention, in particular for producing a section. Such sections are used in particular in the electronics industry. Typical fields of application are, for example, the displays, touch screens and touch pads of mobile devices in communication and entertainment electronics. Furthermore, the polymer thin glass laminate sections according to the invention are preferably used in sensors and optics.

In the following, the method according to the invention for cutting thin polymer-glass laminate is to be explained in more detail on the basis of embodiments, without the examples being intended to restrict it in any form.

• 1 den Produktaufbau eines Polymer-Dünnglas-Laminats in Schnittdarstellung;
• 2 die Verfahrensschritte einer ersten Ausführungsform des erfindungsgemäßen Verfahrens;
• 3 die Verfahrensschritte einer zweiten Ausführungsform des erfindungsgemäßen Verfahrens;
• 4 die schematische Darstellung des Testprinzips des Two Point Bending-Tests nach Gulati.

It shows

• 1 the product structure of a polymer thin glass laminate in a sectional view;
• 2 the method steps of a first embodiment of the method according to the invention;
• 3 the method steps of a second embodiment of the method according to the invention;
• 4th the schematic representation of the test principle of the two point bending test according to Gulati.

In 1 is a laminate of a thin glass film according to the invention 2 and a polymer layer according to the invention 1 shown in section. The polymer and glass have the same thickness, although the invention is not restricted to this. Further layers, preferably further polymer layers, can also be arranged on the thin glass film.

In 2 the method steps of a first embodiment of the method according to the invention are shown (view: section through the laminate). The laminate consists of thin glass film 2 and polymer layer 1 . Here the polymer layer has 1 a smaller thickness than the thin glass film 2 . In step 1 the polymer is made using a laser beam 3 in one width 31 worn away. In step 2 the thin glass is then cut from the glass side by means of a scratching and breaking process, as indicated by the arrows 4a , 4b and 4c is displayed. In step 3 the laminate is separated at the cutting line.

The cut of the glass in step 2 takes place either symmetrically to the center line of the width of the polymer removal 31 according to arrow 4b , asymmetrical on one side to the center line of the polymer removal according to the arrow 4a or 4c or asymmetrically on both sides to the center line of the polymer removal with a section on both by the arrows 4a and 4c marked places.

This creates two separate laminates. These have either a flush and a non-flush edge of polymer layer and glass layer, as shown at 5a, corresponding to a section at 4a in the 2nd step. Alternatively, none of the isolated laminates has a flush edge, as shown at 5b, corresponding to a symmetrical cut at 4b in step 2 . In the third variant, both laminates have a flush edge and a third, isolated piece 6th arises in the width of the cutting line of the polymer removal, as shown at 5c.

In 2 the cutting process steps take place from different sides. The execution from one side is preferred, particularly preferably from the polymer side of the laminate.

In 3 the method steps of a second embodiment of the method according to the invention are shown (view: section through the laminate). Here, the thin glass layer and the polymer layer have the same thickness. In step 1 Here, the thin glass is first cut using a scratch-breaking process, as indicated by the arrow 4th is displayed. In step 2 is then in the area of the scoring 7th The polymer in the thin glass layer is removed by laser, shown here by the arrows 3a and 3b . In step 3 the laminate is separated at the cutting line. In this preferred embodiment, the cutting of the polymer layer is carried out between the two intrinsic steps of scoring and breaking of the scoring-breaking process. This has the advantage that the thin glass passes through the polymer layer when it is scratched is stabilized, but breaking is not made difficult by the adhering polymer layer.

The polymer is removed either symmetrically to the center line of the incision made 7th in thin glass according to arrow 3a or asymmetrically to the center line of the incision made 7th in thin glass according to arrow 3b . This is where the incision lies 7th either in the middle of the width of the resulting polymer removal according to 31a or at the edge of the width of the resulting polymer removal according to 31b. There are two isolated laminates that either have a flush and a non-flush edge of the polymer layer and glass layer, as shown at 5b - corresponding to an asymmetrical removal of the polymer, or in which none of the isolated laminates has a flush edge, as shown at 5a .

Experimental part

The following exemplary experiments are intended to explain the invention in more detail, without wishing to restrict the invention unnecessarily through the choice of the examples given.

Test methods

• Alle Messungen wurden, sofern nichts anderes angegeben ist, bei 23°C +/- 1°C und 50 % +/- 5% rel. Luftfeuchtigkeit durchgeführt.

The following test methods were used to determine the parameters in the examples and the preferred parameters given in the description:

• Unless otherwise stated, all measurements were made at 23 ° C +/- 1 ° C and 50% +/- 5% rel. Humidity carried out.

thickness

The thickness of an adhesive layer, an adhesive tape or a foam layer, a carrier layer or a liner can be determined using commercially available thickness gauges (probe testers) with an accuracy of less than 1 µm. In the present application, the precision thickness measuring device model 2000 F is used, which has a circular probe with a diameter of 10 mm (flat). The measuring force is 4 N. The value is read 1 s after the load. If fluctuations in thickness are found, the mean value of measurements is given at at least three representative points, that is to say in particular not measured at kinks, folds, specks and the like. The thickness of an adhesive layer can in particular be determined by determining the thickness of a section of such an adhesive layer applied to a carrier or liner, which is defined in terms of its length and width, minus the (known or separately ascertainable) thickness of a section of the same dimensions of the carrier or liner used .

Edge strength

The edge strength of the thin polymer glass laminate after the separation step has been carried out is determined with the aid of the two point bending test. This test is widely used in the characterization of thin glasses and is described in the literature ( Gulati et al., ID Symposium Digest of Technical Papers Vol 42, Issue 1, pages 652-654, June 2011 ).

The maximum bending stress is measured or calculated shortly before or exactly at the breaking moment. The laminate (50 x 100 mm ² ) lies with the polymer side up and is fixed on one of the short sides. The other short side is shifted towards the fixed end at a speed of 10 mm / min. The resulting bending stress is measured or calculated from the displacement. This is representative of the edge strength, since the break usually starts from the edge.

The test setup for the two-point bending test with short test pieces is in 4th shown.

The dotted line represents the position and length of the test laminate before bending. The solid line shows the position of the test laminate at the maximum bending, just before the crack.

L is the length of the laminate, ΔL is the distance that one end of the laminate covered during the bending process until shortly before breaking. R is the bending radius and can either be measured or calculated during the test. The thickness of the laminate is abbreviated with d. β is the contact angle which is necessary for the calculation of the maximum bending stress. As the contact angle decreases, so does the tension on the glass.

mit

E:

Elastizitätsmodul des Glases

D:

Abstand der Platten L - ΔL

According to Gulati, the maximum bending stress σ can be calculated from the measured data as follows: $${\mathrm{\sigma }}_{\text{Max}}=1.198\ast \left(\frac{\mathrm{E.}\ast d}{\mathrm{D.}-d}\right)\ast \sqrt{\text{cos}\beta }$$

With

E:

Modulus of elasticity of the glass

D:

Distance between the plates L - ΔL

The maximum bending stress in MPa is given as the edge strength of the polymer thin glass laminate. The mean value from 15 tests is given.

Preparation of the samples

Manufacture of pressure-sensitive adhesive HKM1:

A polystyrene-block-polyisobutylene block copolymer from Kaneka is selected as the (co) polymer. Sibstar 103T (350 g) is used. Escorez 5300 (Ring and Ball 105 ° C, DACP = 71, MMAP = 72) from ExxonMobile, a fully hydrogenated hydrocarbon resin (350 g), is used as the adhesive resin. The reactive resin chosen is Uvacure 1500 from Allnex, a cycloaliphatic diepoxide (300 g). These raw materials are dissolved in a mixture of cyclohexane (950 g) and acetone (50 g) so that a 50% by weight solution is formed.

A latently reactive, thermally activatable initiator is then added to the solution. For this purpose, 3 g of K-Pure TAG 2678 from King Industries were weighed out. The amount of initiator is set up as a 20% strength by weight solution in acetone and added to the above-mentioned mixture.

Using a doctor blade method, the formulation is coated from solution onto a siliconized PET liner and dried at 70 ° C. for 60 minutes. The mass application is 50 g / m ² . The pattern is covered with another layer of a siliconized but more easily separable PET liner.

Further samples are cured by the PET liner without prior lamination at 100 ° C. for 1 hour under the same conditions as specified above. These samples are used for WVTR and OTR measurements (Mocon) and for testing optical properties.

The result from the WVTR measurement (Mocon) is 8 g / m ² · d and from the OTR measurement (Mocon) 830 cm ³ / m ² · d · bar.

Examination of the optical properties of the cured samples after covering both PET liners shows a transmission of 92% and a haze of 1.4%.

• • 23 °C und 50 % relativer Luftfeuchte
• • Unbeheizte Laminierwalzen
• • Laminiergeschwindigkeit 650 mm/min

A thin glass AF32 from Schott with a thickness of 100 μm, a length of 150 μm and a width of likewise 150 μm, which has a modulus of elasticity of 72 MPa, is used as the thin glass. This is fully laminated in a roll-to-roll process with the HKM 1 pressure-sensitive adhesive in the LM 260 roll laminator from Krüger, under the following conditions:

• • 23 ° C and 50% relative humidity
• • Unheated laminating rollers
• • Laminating speed 650 mm / min

The polymer thin glass laminate is then applied from the glass side in the embodiment according to the invention 3 separated into a rectangular shape 50 mm wide and 100 mm long.

For the mechanical scribing-breaking process, a scribing tool is clamped in a holder which is driven by a drive unit and is thus pulled from the glass side over the laminate held on a vacuum table. A diamond pyramid with an angle of 90 ° is used as a scoring tool. The angle between the glass surface and the diamond edge is 5 °. The cutting speed is 1 m / min and the cutting fluid used is ethanol.

The ablative laser procedure is then carried out asymmetrically to the center line of the incision made so that a flush edge of glass and polymer is created on one cut edge and a glass overhang remains on the other edge ( 3 , Variant 5b).

The laser source used is a Coherent Diamond RF-excited CO ₂ laser from Coherent (10-150 W, optimal focal length 5 mm) available from Coherent, Santa Clara, California. The laser is mounted on a movable carriage and the material to be irradiated is held with the glass side on a vacuum table, which can also be moved in the X and Y directions.

The pulse frequency during the cutting process is 25 µs and the pulse overlap is approx. 25%. The maximum pulse energy is 10% and the minimum pulse energy is 5%. The distance between the laser and the polymer surface is 5 mm and the cutting speed is 50 mm / s. The thermal energy introduced into the glass during laser cutting of the polymer layer breaks the glass.

After the cutting process, the resulting sample is evaluated in the two point bending test. The edge strength of the resulting sample, which is produced according to the method explained in the example, is 206 MPa. This corresponds to the edge strength of the same thin glass without a polymer layer, which was scored in the same way and then separated by breaking (226 MPa). The cut edges of the polymer layer appeared without charring and detachment from the glass. This shows that the method according to the invention achieves the object.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2013/050166 A1 [0003]
• DE 69304194 T2 [0008]
• WO 0041978 A1 [0029]
• EP 1832558 A1 [0029]

Non-patent literature cited

• ASTM D1003-11 [0060]
• DIN EN ISO 11145 [0063]
• Gulati et al., ID Symposium Digest of Technical Papers Vol 42, Issue 1, pages 652-654, June 2011 [0092]

Claims (15)

A method for cutting a thin polymer glass laminate, wherein the thin polymer glass laminate consists of at least one layer of a polymer with a thickness of more than 2 µm and less than 500 µm and at least one glass layer with a thickness of 250 µm or less, characterized in that the thin glass is cut by means of a mechanical cutting process and the polymer is cut by means of a laser cutting process. Procedure according to Claim 1 , characterized in that the thin glass is cut by means of a scratch-breaking process. Procedure according to Claim 1 or 2 , characterized in that the thin glass has a thickness of 10 to 150 µm, preferably 20 to 80 µm, more preferably 50 to 120 µm and in particular 30 to 75 µm. Method according to one of the Claims 1 to 3 , characterized in that the polymer has a thickness of 10 to 200 µm. Method according to one of the Claims 1 to 4th , characterized in that the at least one polymer layer is a pressure-sensitive adhesive layer. Method according to one of the Claims 1 to 5 , characterized in that the wavelength of the laser is selected so that the laser beam used for laser cutting is at least partially absorbed by the thin glass. Method according to one of the Claims 1 to 6th , characterized in that the line of the glass cut lies asymmetrically outside the center of the track of the polymer removal taking place by the laser cutting. Procedure according to Claim 7 , characterized in that there are two asymmetrical glass cuts, namely on both sides of the center of the track of the polymer removal carried out by the laser cutting. Procedure according to Claim 7 or 8th , characterized in that the line or lines of the glass section lies or lie in a range of 1 mm, in particular 0.3 mm outside the perpendicular projection of the track of the polymer removal. Method according to one of the Claims 1 to 9 , characterized in that the cutting of the thin glass and the cutting of the polymer are carried out from different sides of the laminate. Method according to one of the Claims 2 to 10 , characterized in that in a first step the thin glass is cut by means of a scratch-breaking process and in a second step the polymer is cut by means of laser cutting. Method according to one of the Claims 2 to 9 , characterized in that the cutting of the thin glass and the cutting of the polymer are carried out from the same side of the laminate, namely the polymer-coated side, and that the laser cutting process is carried out in a first step and the scratch-breaking process is carried out in a second step. Method according to one of the Claims 2 to 9 , characterized in that the cutting of the thin glass and the cutting of the polymer are carried out from the same side of the laminate, namely the glass side, and that in a first step at least the scratching of the scratch-breaking method and in a second step the laser cutting method are carried out becomes. Polymer thin glass laminate section obtainable by at least one cut by a method according to one of the Claims 1 to 13th . Using a polymer thin glass laminate section according to Claim 14 in electronic devices.

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