Method and apparatus for hot plate welding of thermoplastics

Abstract

The present invention provides a method for thermal welding of thermoplastics using a hot plate, said method comprising the steps of: a) heating the hot plate to a temperature required for welding the thermoplastics, and bringing the thermoplastics to be welded into contact with the hot plate until the areas of the thermoplastics to be welded melt, and b) removing the thermoplastics from the hot plate, joining the areas of the thermoplastics and pressing them together to weld them, wherein the hot plate body is made of a material selected from the group of metal, metalloid, metal oxide, metalloid oxide, metal nitride, metalloid nitride, metal oxynitride, ceramic and / or glass, and the hot plate is provided with a polymer brush on one or more surfaces intended for contact with the thermoplastics. In further aspects, the invention discloses a device and a hot plate useful in the method.

Description

[0001] Method and apparatus for hot plate welding of thermoplastics

[0002] Field of Art

[0003] The present invention relates to improvements in the process of hot plate welding of thermoplastics, and to an apparatus for carrying out such improved process.

[0004] Background Art

[0005] Hot plate welding is athermal welding technique for joining thermoplastics. A heated hot plate is placed against or near the two surfaces to be joined, in order to melt them. The heat source is then removed and the surfaces are joined under pressure. Hot plate welding has relatively long cycle times, ranging from 10 seconds to minutes, compared to vibration or ultrasonic welding. However, its simplicity and ability to form strong bonds with almost all thermoplastics make it widely used in mass production, such as the production of tanks for the automotive industry or toys, and for large structures, such as large diameter plastic pipes. The hot plate welding process is based on pressing the material against a hot plate, the temperature of which is set between the melting point and the degradation temperature of the polymer. The pressure depends on the material and it is advantageous to change it during welding.

[0006] The hot plate welding process can be divided into four phases: adaptation, heating, exchange and welding / forging.

[0007] The adaptation phase serves to adapt the geometry of the surfaces to be welded to the theoretical welding plane. The surfaces to be welded are heated by conduction through physical contact with a hot plate. The temperature range of the hot plate is most often set within the range of 30 to 100 °C above the melting point of the material to be welded, and a constant pressure is applied to the hot plate depending on the material, typically between 0. 1 and 1 MPa. This causes the surfaces to be welded to adapt to the hot plate, which has the desired weld geometry. This also removes surface irregularities that would increase the thermal contact resistance. Once the surfaces to be welded are in full contact with the hot plate, the heating phase begins and the pressure is reduced to a minimum.

[0008] During the heating phase, the area of the weld is conductively heated until it melts, without any significant material displacement. The pressure is either kept at a minimum so that the parts to be welded and the hot plate are in contact, or at zero with a pre-set offset. The melted surface of the parts reaches a temperature approximately 20°C below the hot plate temperature. The viscosity of the molten material can be controlled by the hot plate temperature and the heating time.

[0009] The surface of the hot plate is often coated with polytetrafluoroethylene (PTFE) to prevent the molten plastic from sticking, which limits the maximum temperature of the hot plate to 270°C. Furthermore, the PTFE may peel off from the hot plate or the PTFE layer may gradually lose its anti-adhesive properties.

[0010] After a sufficient heating time, the transfer phase begins. During this phase, the parts are removed from the hot plate, the plate is quickly moved away and the parts are joined. The transfer should be as short as possible, as the molten area cools down during this time.

[0011] In the welding phase, the two molten surfaces (parts) are pressed together. This creates intermolecular diffusion of the thermoplastic molecules according to the reptation theory. The strength of the weld is ensured by the entanglement of the diffusing plastic molecules. The required welding pressure depends on the viscosity of the melt and the wall thickness of the parts to be welded and is usually between 0.025 and 0.05 MPa.

[0012] To day, the risk of the molten plastic sticking still remains a problem, even when using an anti-adhesive PTFE layer. If a piece of plastic sticks to the hot plate, during further welding this material causes sticking of further portions of plastic, and finally the stuck plastic has to be removed from the hot plate mechanically, which both destroys the plate and also costs the welding machine operator effort and time. To day, hot plates are generally made of metal, as with other materials, especially glass, there would be a high risk of plastic sticking.

[0013] Summary of the Invention

[0014] The present invention provides a method for thermally welding thermoplastics using a hot plate, said method comprising the steps of: a) heating the hot plate to a temperature required for welding the thermoplastics, and bringing the areas of thermoplastics to be welded into contact with the hot plate until the areas to be welded of the thermoplastics are melted, and b) removing the thermoplastics to be welded from the hot plate, joining the areas to be welded of the thermoplastics and pressing them together, wherein the body of the hot plate is made of metal, metalloid, metal oxide, metalloid oxide, metal nitride, metalloid nitride, metal oxynitride, ceramic and / or glass and wherein the hot plate is provided with a polymer brush on one or more surfaces destined for contact with the thermoplastics.

[0015] In another aspect, the present invention provides a device for welding plastics, which contains a hot plate and means for pressing the thermoplastics at the location of the weld to be formed. The hot plate may constitute or contain a heating element, or the device may further contain a heating element. The body of the hot plate is made of metal, metalloid, metal oxide, metalloid oxide, metal nitride, metalloid nitride, metal oxynitride, ceramic and / or glass and wherein the hot plate is provided with a polymer brush on one or more surfaces adjusted for contact with the thermoplastics.

[0016] The temperature required for welding thermoplastics is preferably a temperature higher than the melting temperature of the thermoplastics to be welded, more preferably a temperature which is 30 to 100 °C higher than the melting temperature of the thermoplastics to be welded.

[0017] Typically, in step a) a constant pressure is applied against the hot plate, selected depending on the material of the plastic to be welded, typically between 0.1 and 1 MPa.

[0018] The welding pressure in step b) depends on the viscosity of the melted material and the wall thickness of the parts and is usually between 0.025 and 0.05 MPa.

[0019] The term “hot plate” herein means a plate that is used to heat the thermoplastics to be welded. It is a plate that can be heated to the temperature required to melt the given thermoplastics. The term “hot” here does not therefore indicate a specific temperature or temperature range. „Hot plate“ is a well- established term in the field. The hot plate can have various shapes, for example, it can be flat and straight, or it can have a shape corresponding to the shape of the future weld, i.e. for example a shape with protrusions and recesses.

[0020] The terms „material“ and „part(s)“ refer to the thermoplastic material or thermoplastic parts which is / are welded.

[0021] The metal of the hot plate body can preferably be selected from Group IIIA metals, Group IVA metals, transition metals, and metalloids. Metals and metalloids also include alloys of the aforementioned metals and metalloids.

[0022] The hot plate body may preferably be made of a metal selected from the group comprising aluminium, aluminium alloys such as duralumin, titanium, titanium alloys, iron, steel, cast iron, copper, copper alloys, chromium, titanium, zirconium, magnesium, niobium, tantalum, zinc, alloys of the said metals, for example brass or bronze.

[0023] The metalloid may be, for example, silicon.

[0024] The metal oxides and metalloid oxides preferably include silicon dioxide, aluminium oxide, titanium oxide, zirconium oxide, chromium oxide, indium tin oxide (ITO), fluorine-doped tin oxide, aluminium- doped zinc oxide, zinc oxide. The metal nitrides and metalloid nitrides may preferably be selected from nitrides of boron, silicon, titanium or aluminium.

[0025] The metal oxynitrides preferably include, for example, oxynitrides of aluminium, titanium, zirconium, indium, tin, or chromium.

[0026] The glass may be common glass (silica-based glass), soda glass, borosilicate glass, quartz.

[0027] The surface of the hot plate body may preferably be roughened to further increase the non-sticking properties. The surface roughening may be in the order of units to hundreds of microns (i.e. on the microscale) or in the order of units to hundreds of nanometers (i.e. on the nanoscale). For example, the surface roughening may be on the scale of 5 nm to 5 micrometers.

[0028] The roughening of the hot plate surface may be carried out in many ways. Examples include chemical or plasma etching, for example anodizing in the case of metal hot plates, reactive plasma etching using Ch; treatment with piranha solution (a mixture of sulfuric acid and hydrogen peroxide) or treatment with low-temperature SFg plasma, especially in the case of glass hot plates; applying nano or microparticles (preferably made of the same material as the hot plate, but they can alternatively be made of a different material) to the surface of the substrate and melting them so that they firmly adhere to the surface of the hot plate.

[0029] Furthermore, when the material of the hot plate surface is not suitable for direct bonding of the selected polymer brush, a layer of coating may be applied to the surface of the hot plate, to which the polymer brush can be bound. Such coating may be, for example, a metal oxide or a metalloid oxide, in particular SiCE, or a metal nitride or a metalloid nitride, or a metal oxynitride. In some embodiments, the coating layer may be a gradient layer, with a gradual transition from the plate material to the desired surface material. In some embodiments, the thickness of the coating may preferably be 1 nm to 10 micrometers, more preferably 100 nm to 1 micrometer. (Thicknesses of thin layers may be determined based on the deposition rate measured using a quartz microbalance, or by direct measurement using profilometry.) It is also possible to activate the surface of the hot plate, for example by the action of oxygen plasma, ozone or by the action of an alkaline solution and / or piranha solution. The aim of activation is to provide functional groups on the surface suitable for binding a linker or a polymer chain. Another manner of activation is the formation of a metal oxide or a metalloid oxide on the surface of a metal hot plate, for example by oxidation or anodization of the metal surface, or by direct deposition of the oxide.

[0030] Polymer brushes are well known to those skilled in the art of polymers. Polymer brushes are polymer chains bound to the surface of a substrate (here the substrate is a hot plate, or a hot plate coating) by one of their ends; in the case of branched chains, the chain may be bound by multiple ends, with the chain pointing away from the substrate. Alternatively, polymer brushes are also known that are bound to the surface of the substrate by both ends of the chain, with the chain between the two ends being arranged so as to point away from the substrate.

[0031] Polymer brushes are currently typically used as antifouling surfaces, i.e. surfaces that prevent the adhesion of components of mixtures, that come into contact with the surface, to this surface. Antifouling surfaces are used, for example, on biosensors or medical surfaces to prevent the adhesion of components of biological media or biological samples to these surfaces and to prevent unwanted interaction with the measurement on the biosensor.

[0032] Polymer chains of the polymer can be bound to the substrate by only one end, with the other end unbound and directed away from the surface. In the case of multi-armed (branched) chains, they can be bound to the surface by more than one end, or by only one end, while one or multiple free ends are directed away from the surface. In some embodiments, polymer chains can be bound to the substrate by both ends, with the chain between the two ends directed away from the substrate surface.

[0033] Polymer brushes are usually bound to the surface of substrates (here, the hot plate body) either by physical adsorption or by covalent bonding. Covalent attachment can be achieved either by surface- initiated polymerization (grafting from) or by grafting pre-prepared polymer chains from solution onto the substrate (grafting to). High density of polymer chains can be achieved in particular by grafting at the edge of solubility.

[0034] It may be necessary to bind linkers to the substrate surface in order to bind the polymer chains via the linkers. Linkers can be molecules or their residues that bind to the substrate surface and have a functional group to which the terminal group of the polymer chain can be bound.

[0035] Polymer brushes are typically made up of chains of linear homopolymers, linear block copolymers, linear random copolymers, branched homopolymers, branched block copolymers, and / or branched random copolymers.

[0036] Polymer brushes can preferably be selected from polymers such as polyethylene glycol, polyethylene glycol ether, perfluoroalkane, poly(perfluoroalkane), polystyrene, poly(methacrylic acid), poly(methyl methacrylate), poly(methacrylamide), poly(acrylamide), poly(hydroxyethyl acrylate), poly(hydroxyethyl methacrylate), poly(N-isopropylacrylamide), poly(sulfobetaine methacrylate), poly(carboxybetaine methacrylate), poly(sulfopropyl methacrylate), poly(2-hydroxyethyl methacrylate), poly(oligo(ethylene glycol) methacrylate), poly(methacryloyl oxyethyl phosphorylcholine), cationic poly (methacryloylcholine), poly((dimethylamino)ethyl methacrylate), poly(2-perfluorooctylethyl methacrylate), poly(2-vinylpyridine), polysaccharides, polybenzimidazole, poly(2-oxazoline), polycarboxybetaine, polysulfobetaine, polylactic acid, polyglycolic acid, poly(lactic- block-glycolic) acid, polyglycerol, poly(sodium styrene sulfonate), poly(ethylene oxide)-block- poly(propylene oxide), polystyrene-block-poly(methyl methacrylate), polyethylene glycol)-block- polylactic acid, poly(vinyl alcohol), and copolymers containing blocks of said polymers or statistically (random) distributed monomers of these polymers.

[0037] Furthermore, polymer brushes with very high thermal stability can be selected from the group comprising polydimethylsiloxane, polyimide, polyether ether ketone (PEEK), polytetrafluoroethylene), polystyrene, poly(phenylene sulfide), polyglycerol, poly(ethyleneimine), and copolymers containing blocks of said polymers or statistically distributed monomers of these polymers.

[0038] The polymer brush chains can be provided at one end with a first functional group enabling binding to a substrate or to a linker, and / or at the other end with a second functional group increasing the resistance to sticking of the plastic being welded.

[0039] The first functional group may preferably be selected from COOH, OH, NH2, silane (e.g. Si PF. SijH . alkoxysilanes such as tri(Cl-C3)alkoxysilane, alkylsilanes such as tri(Cl-C3)alkylsilane), thiol, N- hydroxysuccinimide (NHS), l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), succinimidyl valerate (SVA), epoxy, azide, alkyne, tetrazine, carbodiimide, maleimide, bis(amine), 2- glycidoxypropyl trimethoxy silane, dibenzocyclooctyne, trans-cyclooctene, nitrodopamine, or residues derived from the aforementioned groups upon binding to the substrate. These groups readily form amide or ester or other covalent bonds, or form bonds via so-called click reactions.

[0040] The second functional group can preferably be selected from CH3, OCH3, OC2H5, CF3, COOH, NH2, OH, SH, N3, C2H4O, CHO.

[0041] Alternatively, the same first functional group can be used at both ends of the chain, which can increase the yield of the reaction of the bound chains, when the surface contains chains bound by one end to the substrate as well as bound by both ends to the substrate.

[0042] In one preferred embodiment, the polymer chain is polyethylene glycol monomethyl ether (e.g. with MW 5000), polyethylene glycol monomethyl ether - succinimidyl valerate (mPEG-succinimidyl valerate, e.g. with MW 5000).

[0043] The polymer chains of the polymer brush may preferably have a molecular weight in the range of 300 to 200,000, more preferably 1,000 to 40,000. To increase the anti-adhesive effect, shorter chains with a molecular weight in the range of 200 to 10,000 can be further used to link these chains one to another.

[0044] The polymer brush layer typically has a thickness in the range of 1 to 1,000 nm, more preferably 2 to 200 nm. The thickness of the polymer brush layer is determined, for example, from the gyration radius of the polymer chains, or by spectroscopic ellipsometry. The molecular weight is given in this text as a number without a unit, which corresponds to the notation in unified atomic mass units (u). The specific molecular weights of the polymers are given in the notation "MW value", where the value is the molecular weight in unified atomic mass units.

[0045] The linkers preferably have a functional group selected from the group COOH, OH, NH2, silane (e.g. SiH,. SijH . alkoxysilanes such as tri(Cl-C3)alkoxysilane, more precisely derived from (3- aminopropyl)triethoxysilane), phosphonic acid, thiol, N-hydroxysuccinimide (NHS), succinimidyl valerate (SVA), epoxy, azide, alkyne, carbodiimide, maleimide, bis(amine), 2-glycidoxypropyl trimethoxysilane, dibenzocyclooctyne, or residues derived from the aforementioned groups upon binding to the substrate. These groups readily form amide or ester bonds or form bonds via click reactions with precursors of the first functional groups of the polymer chains.

[0046] For “grafting from” reactions, the linker is typically a residue of an ATRP (atom transfer radical polymerization) initiator, a RAFT (reversible addition-fragmentation chain transfer) initiator, a SIRP (surface-initiated radical polymerization) initiator, a ROP (ring-opening polymerization) initiator, a SIROP (surface -initiated ring-opening polymerization) initiator, or a photopolymerization initiator. These initiators are known to those skilled in the art.

[0047] In some embodiments, the linker may be (functionalized alkyl-)phosphonic acids for binding polymer brushes to metal substrates, particularly to aluminum, chromium, titanium, or stainless steel; silanes for binding polymer brushes to glass; APTES ((3-aminopropyl)triethoxysilane), MPTES ((3- mercaptopropyl)triethoxysilane), GOPTS ((3-glycidyloxypropyl)trimethoxysilane) or GPTES (3- glycidyloxypropyl)triethoxysilane) for binding polymer brushes to various substrates, in particular to glass. Diazonium, may be used for binding brushes to carbon containing surface, while benzophenone for surface initiated photopolymerization brush growth.

[0048] The heating element may be the hot plate itself, if it can conduct heat by itself - for example, a hot plate made of metal. Alternatively, the hot plate may be provided with a heating element so that it is in direct thermal contact with the heating element, in some embodiments the heating element may form a layer covering the hot plate. Furthermore, the device may be provided with a heating element that heats the hot plate without direct contact.

[0049] More specifically, the heating element may be a resistive element, an electromagnetic element, or a light-radiation element.

[0050] More specifically, the heating element may be, for example, a heating coil, a resistive layer, a transparent conductive metal oxide layer (such as ITO, FTO, AZO), an electromagnetic induction heater, a halogen lamp, or an infrared light source. A number of different configurations of a hot plate provided with a polymer brush may be designed, achieving various technical advantages.

[0051] In the simplest embodiment, a hot plate made of any of the above materials is provided, provided on one surface or on two opposing surfaces with a polymer brush (optionally also with a coating, roughening, and / or linker, as described hereinabove). Generally, in the present invention, the surface provided with a polymer brush is the surface that comes into contact with the thermoplastic during the welding of thermoplastics.

[0052] Such two plates treated on one side with a polymer brush can be connected to a heating element in such a way that the heating element is arranged between the plates. The heating element is, for example, a plate containing a heating spiral or a coil for induction heating or an infrared heating element. Then both surfaces are used to melt the welded areas of the welded thermoplastics.

[0053] The provision of two opposite surfaces of a hot plate with a polymer brush is particularly suitable when the material is a good heat conductor and has a high heat capacity (e.g. metal), and the plate is then preferably heated in the docking position and its heat capacity is used during welding. In the case that the plate is made of a material that allows induction heating, i.e. based on metals, for example iron, steel, copper, aluminum, the plate is inductively heated in the docking position.

[0054] In some embodiments, the hot plate has a surface containing carbon. Such surface may preferably contain metal and metalloid carbides, such as carbides of Ti, Zr, W, Cr, V, Nb, Si, B and / or Ta, diamondlike layer (DLC), amorphous hydrocarbon layer, amorphous carbon layer and / or amorphous carbon layer with metal. Polymer brushes may be bound directly to the carbon-containing surface.

[0055] In an embodiment where the plate material is transparent (e.g. the material is glass), two transparent plates provided with a polymer brush can be mounted on a light-radiation heating element, for example an infrared heating element, such as a halogen heating element, arranged between the plates. The light radiation allows only the plastic in contact with the plate to be heated, with the plate itself serving for uniform melting. This allows not only the pressure but also the temperature to be changed simply and quickly during welding.

[0056] Preferably, a transparent hot plate (e.g. with low heat capacity and conductivity) can be covered with a layer absorbing radiation from the light-radiation heating element, thus heating the surface of the plate. Preferably, the absorbing layer absorbs infrared radiation. Such absorbing layer can be, for example, a diamond-like layer (DLC), titanium carbide, titanium carbide nitride, zirconium carbide, a gradient layer of titanium carbide-titanium oxide or aluminum nitride-aluminum oxide, ITO, antimony tin oxide, tungsten oxide, vanadium oxide, chromium oxide, LaBg, titanium aluminum nitride, titanium oxynitride. A polymer brush is bound to the absorbing layer. A typical example of such an embodiment is a gradient layer of TiC-TiCE, using a linker with phosphonic acid, or a DLC layer that can be exposed to O2 / H2 plasma with subsequent functionalization using APTES. By applying an infrared absorbing layer, the light absorption efficiency can be increased and the required power of the light-radiation element can be reduced.

[0057] Preferably, the transparent hot plate can be provided with a nano- or microstructure on the surface, and optionally this nano- or microstructure can be provided with a layer absorbing radiation from the lightradiation heating element, and the nano- or microstructure and / or optionally the layer absorbing radiation from the light-radiation heating element can be provided with a polymer brush. On the side of this hot plate opposite to the side provided with the polymer brush, a light-radiation element can then be placed, or the light-radiation element can be provided with two such hot plates on two sides. The nano- or microstructure can be formed, for example, by nanoparticles of metal (Al, Ti), or metal oxide (ITO, antimony tin oxide, tungsten oxide, vanadium oxide), or metal nitride (titanium aluminum nitride, titanium oxynitride, aluminum nitride), these nanoparticles are sintered onto the surface of a hot plate at a temperature below the melting point of the material, thereby creating a structure with a roughness of 5 nm to 5 pm, which can be further functionalized with a polymer brush. The advantage of this embodiment is that the contact area of the plastic and the plate is reduced, and at the same time the optical absorption of such a plate is increased.

[0058] In some embodiments, the hot plate includes a heating element. The heating element may be, for example, a metal plate, a wire heating coil, a light-radiation element (e.g., halogen, infrared) or, in the case of a non-conductive plate material, a resistive thin fdm.

[0059] In particular, in the case of a transparent plate material, a layer of transparent conductive oxide (TCO) is preferably applied as the heating element, which may be, for example, indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). The use of TCO has the advantage of maintaining the transparency of the hot plate, which allows for easy optical inspection of the plate condition, including automated inspection. In addition, polymer brushes can be bound to the TCO.

[0060] The heating element can be applied onto the hot plate on the surface opposite to the surface provided with the polymer brush (example of order of layers: heating element, hot plate, polymer brush), or on the surface provided with the polymer brush (example of order of layers: hot plate, heating element, polymer brush), or between two hot plates (example of order of layers: polymer brush, hot plate, heating element, hot plate, polymer brush). More specific examples of this configuration are the following layer order: glass, TCO layer, polymer brush; or polymer brush, glass, TCO layer, glass, polymer brush; or polymer brush, glass, heating coil, glass, polymer brush.

[0061] The transparent hot plate allows for a one-time or repeated diagnosing of the hot plate condition during the welding process, when, while the areas to be welded of the thermoplastics are being pressed together, the hot plate, which is not in use at that moment, is inserted between the light source, and the camera, and the camera takes an image from which it is evaluated whether the surface of the hot plate is damaged or whether any welded thermoplastic has adhered to it. It should be noted that the polymer brush layer does not negatively affect the transparency of the hot plate. In the event of damage or adhered thermoplastic being detected, the welding is interrupted and the hot plate is subjected to service treatment to remove the damage or the adhered thermoplastic, or is replaced.

[0062] In some embodiments, the transparent hot plate or the transparent part of the hot plate on the side opposite to the surface provided with the polymer brush may have a metal reflective layer. In addition to the metal reflective layer, a heating element may also be present.

[0063] Examples of possible embodiments in this configuration are the following orders of layers: metal reflective layer, hot plate, polymer brush; or heating element, metal reflective layer, hot plate, polymer brush; or metal reflective layer, hot plate, TCO layer, polymer brush; or polymer brush, hot plate, metal reflective layer, heating element, metal reflective layer, hotplate, polymer brush. In these embodiments, the hot plate is preferably made of glass.

[0064] The transparent hot plate allows for a one-time or regular diagnosis of the hot plate condition during the welding process, where at the time when the welded areas of the welded thermoplastics are compressed together, the hot plate, which is not in use at that moment, is placed near the light source and the camera, so that the light source illuminates the hot plate and the camera scans the surface of the hot plate with the reflected light from the light source, and the images from the camera are used to evaluate whether the surface of the hot plate is damaged or whether any welded thermoplastic has adhered to it. In the event of damage or adhered thermoplastic, the welding is interrupted and the hot plate is subjected to service treatment to remove the damage or adhered thermoplastic.

[0065] In addition to the hot plate, the thermoplastics welding device also includes means for compressing the thermoplastics at the weld site. Such means may be, for example, opposing jaws or opposing rollers, or other means known to a person skilled in the art. The device thus comprises means for moving the hot plate and / or for moving the means for compressing the thermoplastics. In the case of transparent hot plates or hot plates covered with a reflective layer, the device may further comprise a light source and a camera.

[0066] Examples

[0067] Example 1

[0068] A) Activation. As a first step, the hot plate body was activated by hydroxyl (-OH) groups. The glass flat plate (hot plate body) was first sonicated in acetone for 10 minutes, then for 5 minutes in a 50:50 water- isopropanol solution and for 5 minutes in deionized water and dried with a nitrogen stream. The cleaned plate was activated with hydroxyl groups by exposure to oxygen plasma for 10 minutes at 100W power, or alternatively by exposure to 3M NaOH solution for 5 minutes and then to piranha solution, i.e. sulfuric acid and hydrogen peroxide in a ratio of 5: 1, for 10 minutes.

[0069] B) Silanization : In the next step, the -OH activated substrate (hot plate body) was functionalized with (3 -aminopropyl)triethoxy silane (APTES) as follows: the glass substrate was immersed in a 2% (v / v) solution of APTES in acetone at 40 °C for 30 min. After removal from the solution, the substrate was allowed to dry.

[0070] C) Grafting. Polyethylene glycol) monomethyl ether succinimidyl valerate with a molecular weight of 5000 (mPEG5000-SVA) was attached to the primary amino groups of APTES as follows: a carbonatebicarbonate buffer was prepared as follows. 100 ml of aqueous solution contained NaHCCf 623 mg, NazCCE 274 mg and 10 g K2SO4. The pH of this solution was approximately 9.5. mPEG5000-SVA was dissolved in this solution to a concentration of 10% (w / v). At this concentration, the polymer was in a collapsed state at the solubility limit. The functionalized glass substrate was immersed in this mPEG5000-SVA solution for 1 hour at room temperature. After incubation, the substrate was washed with water and dried with nitrogen. The resulting polymer brush layer had a thickness of approximately 5 nm. The approximate layer thickness was estimated from the radius of gyration of the polymer chains.

[0071] D) Heating element. To heat the hot plate, the glass body of the hot plate was provided with a heating resistance element, namely a plate containing a heating coil, inside or on the side that does not come into contact with the plastic to be welded. In other exemplary embodiments, a thin resistive layer of transparent conductive oxide (TCO), an infrared light source or an electromagnetic induction heater was used.

[0072] E) Welding. A glass plate (hot plate) coated with a polymer brush mPEG5000-SVA was heated to various temperatures from 175 °C to 200 °C and glass fiber-filled polypropylene was pressed onto the heated hot plate at a pressure of 0.05 MPa for 3 seconds. No traces of polypropylene were subsequently found on the hot plate. In a comparative experiment, a glass plate without a polymer brush, i.e. only glass, was used under the same conditions, and the polypropylene adhered to the glass at these temperatures. Example 2

[0073] The hot aluminum plate was shaped according to the future weld of the product (liquid tank) to be welded, where the easy machinability of aluminum was used to produce a given shape. This aluminum plate was anodized, which created aluminum oxide on it. In other embodiments, duralumin, Ti, Mg, Nb, Ta, Zr, or their alloys were used, which were also anodized. In other embodiments, a Cr or stainless steel plate was used, which did not require anodization, where the formation of stable chromium oxide was used. Anodization led to increased roughness and porosity and therefore to a reduction in the contact area of the welded product with the plate material. In other embodiments, the plate was made of Cu, brass or bronze, a material that allowed rapid temperature cycling, cast iron, to prevent excessive thermal expansion. Anodization was not possible with these materials, therefore, the deposition of a thin 200 nm layer of Si Oi using magnetron sputtering was used. In another embodiment, a transition layer of SiCf was deposited from hexamethyldisiloxane using plasma-enhanced chemical vapor deposition. In another embodiment, a titanium plate was coated with a 1 pm gradient layer from Ti to titanium oxynitride. The metal oxide-coated substrates were activated, silanized, grafted, and provided with a heating element according to Examples 1A-1D, and welding was performed according to Example IE.

[0074] Example 3

[0075] A hot plate for welding plastics was prepared from a flat glass substrate (body) that was activated and silanized according to Examples 1A and IB. Three weights of the mPEG-SVA polymer chain were used for grafting, namely MW=40,000, 5,000 and 300. In the first grafting step, the incubation was performed in the same way as in example 1C, with the difference that a carbonate-bicarbonate buffer prepared from commercially available capsules, which had a pH of 9.3 and mPEG-MW40000-SVA was used. Subsequently, the surface prepared in this way was sonicated for 10 minutes in deionized water, which washed away the polymer chains that were not covalently bound. In the second step, grafting was performed in the same way, only using a shorter mPEG-MW5000-SVA chain, this chain filled the empty spaces between the long polymer chains with MW=40,000. In the third step, the shortest mPEG- MW300-SVA chain was grafted. This resulted in a hot plate with covalently attached chains of 2 to 320 nm in length. The heating element was attached as in Example ID, and the welding was performed as in Example IE.

[0076] Example 4

[0077] The hot plate was prepared by activation as in Example 1A, and then functionalized with MPTES. The glass was placed in a 2% (v / v) solution of MPTES in ethanol and kept at room temperature for 1 h. The glass was then sonicated for 10 min in ethanol and deionized water. In the next step, a mixture of polymer chains in a weight ratio of 1: 1 NH2-PEG-MW5000-Maleimide and COOH-PEG-MW5000-Maleimide was grafted (bound) in a commercial PBS buffer at pH 7.4, by incubation in an aqueous solution with a concentration of 10% (w / v), then the plate was sonicated for 10 minutes in ethanol and deionized water. Then the substrate was placed in a solution of DMTMM (4-(4,6-dimethoxy- 1,3, 5 -triazin-2 -yl)-4- methyl-morpholinium chloride) with a concentration of 1 mg / ml in PBS buffer at pH 7.0, which caused the reaction of adjacent NH2 and COOH chains. Thus, the PEG chains were attached by two ends to the substrate, which increased their mechanical stability. Such a surface was then used for welding according to examples ID, E.

[0078] Example 5

[0079] The hot plate was activated as in Example 1 A. The plate was placed in a beaker, and GOPTS or GPTES was added, incubated for 4 h, and then sonicated in anhydrous acetone. After drying with nitrogen, the plate was placed in a beaker, poured with molten mPEG-MW5000-NH2, heated to 90 °C, and placed in an oven at the same temperature for 2 days. This caused the PEG to be covalently bound to the surface via the epoxy groups. Deionized water was then poured into the beaker, which dissolved the PEG, which could be removed from the plate. The plate was then sonicated in ethanol and water for 10 min. Such a plate was provided with a heating element as described in Example ID, and then used for welding as in Example IE.

[0080] In other embodiments, mPEG-MW5000-GH, mPEG-MW5000-SH, CGOH-MW5000-COOH, or NH2- MW5000-NH2 were used.

[0081] Example 6

[0082] The hot plate was activated according to Example 1A. Then, perfluoroalkane chains of (heptadecafluoro- 1,1, 2, 2-tetrahydrodecyl)trimethoxysilane were deposited in the gas phase by vapor deposition, when 200 pL of this substance was placed in a desiccator, which was heated to 60°C for 2 hours. The thus prepared plate was sonicated after 10 minutes in isopropanol and water. The thus prepared polymer brushes terminated with a hydrophobic CF3 group were used for installation of the hot element, as described in Example ID and welding according to Example IE.

[0083] Example 7

[0084] The hot plate was activated according to Example 1 A. Then, a short chain of azido-PEG3-triethoxysilane was attached. A solution of this silane was prepared in a ratio of 25% (v / v) in DMSO and dropped onto the activated plate at a temperature of 90 °C, incubation was continued in an oven at this temperature for 1 hour. On these short active chains, mPEG-MW5000-DBCO (dibenzocyclooctyne) dissolved in water in a ratio of 10% (w / v) was grafted, using a carbonate-bicarbonate buffer, at pH 9, and adding 10g K2SO4 to the solubility limit. Altemativelly mPEG-MW5000-Alkyne was used, with addition of 0.1% (w / v) of CuSO4 and 0.1% (w / v) of tris(3-hydroxypropyltriazolylmethyl)amine catalysts. Alternatively, short chain of Trans-cyclooctene-triethoxysilane was bound to surface, followed by addition of mPEG- MW5000-Tetrazine in above mentioned buffer. The incubation time was 24 hours, since the use of clickchemistry (DBCO-azide, Alkyne-azide or Trans-cyclooctene-Tetrazine) eliminated the problem of hydrolysis of SVA groups. After incubation, the substrate was washed with water and dried with nitrogen. Such a plate was equipped with a heating element according to Example ID and then used for welding according to Example IE.

[0085] Example 8

[0086] An anodized aluminum hot plate was sonicated for 10 minutes in isopropanol and deionized water. In another embodiment, a titanium plate was used that was oxidized using oxygen plasma. The plate was then exposed to mPEG-MW5000-nitrodopamine at a concentration of 0.1 g / L dissolved in HEPES buffer at pH 7.4 containing 0.6 M NaCl and 0.6 M K2SO4 for 3 h at room temperature, and after this incubation was washed with deionized water. Such a plate was provided with a heating element according to Example ID and then used for welding according to Example IE.

[0087] Example 9

[0088] The hot plate was activated and silanized according to Examples 1A, IB. Then OH-PEG-MW5000- NHS in an aqueous solution of 10% (w / v) was grafted onto it. In another embodiment, four-armed 4- ArmPEG-SPA (SPA = succinimidyl propionate) or eight-armed 8-ArmPEG-SC (SC = succinimidyl ester) was used. Such a plate was provided with a heating element according to Example ID and then used for welding according to Example IE.

[0089] Example 10: ATRP polymerization

[0090] A) surface initiation: A hot glass plate was activated and silanized according to examples 1A, B. It was then placed in a solution of bromoisobutyryl bromide 1% (v / v) and triethylamine 1% (v / v) in dichloromethane for 30 min. It was then sonicated in dichloromethane and isopropanol for 10 min, and dried in nitrogen.

[0091] In another embodiment, 3-(trichlorosilyl)propyl-2-bromo-2-methylpropanoate was used, which was deposited in the gas phase for 15 min.

[0092] This prepared the plate for surface-initiated atom transfer radical polymerization (SI-ATRP).

[0093] B) polymerization : In the next step, the activated plate was placed in an aqueous solution of methanol with deionized water in a volume ratio of 1: 1, containing CuBr (5 g / 1) and bipyridine (12 g / 1) together with IM zwitterionic monomer [2-(methacryloyloxy)ethyl]dimethyl(3-sulfopropyl)ammonium hydroxide (SBMA), and was incubated in an argon atmosphere for 24 h. This resulted a polymer brush of poly (sulfobetaine methacrylate). The plate was then sonicated in isopropanol and water for 10 minutes. In another embodiment, the monomer sodium 3 -sulfopropyl methacrylate (SPMA) was used, and a polymer brush of poly(sulfopropyl methacrylate) was prepared analogously.

[0094] In another embodiment, 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate was used to prepare a polymer brush of poly (carboxybetaine methacrylate).

[0095] In another embodiment, the oligomer oligo(ethylene glycol) methacrylate (OEGMA) was used instead of the monomer, leading to a poly(OEGMA) brush. In another embodiment, the copolymer POEGMA- b-PMMA was prepared analogously.

[0096] In another embodiment, the monomers methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) were used to form a random copolymer polymer brush.

[0097] In another embodiment, the monomer 2-hydroxyethyl methacrylate (HEMA) was used to prepare a poly(2 -hydroxyethyl methacrylate) brush.

[0098] In another embodiment, the monomer methacryloyl oxyethyl phosphorylcholine (MPC) was used to prepare a zwitterionic polymer poly(MPC).

[0099] In another embodiment, the monomer sodium methacrylate (MAA-Na) was used for a poly(methacrylic acid) polymer brush.

[0100] In another embodiment, the cationic monomer methacryloylcholine chloride (METAC) was used for the poly(METAC) polymer brush, however, the solvent in these cases was aqueous without methanol.

[0101] In another embodiment, the monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA) was used, but instead of CuBr, the photocatalyst 10-methylphenothiazine (MPT) was used, which was added at 2 mM per 1 M monomer with the addition of 2 mM ethyl a-bromophenylacetate, when the plate was illuminated with a wavelength of 380 nm during the preparation, thus poly(dimethylaminoethyl methacrylate) polymer brushes were prepared.

[0102] 1 ml (2-perfluorooctylethyl methacrylate) (MAF17) was mixed with 1 ml trifluorotoluene and 25 mg 4,4'-dinonyl-2,2'-dipyridyl (dNbpy) in a flask, this solution was placed in liquid nitrogen and after freezing 5 mg CuBr was added. Then the flask was evacuated, the mixture was heated to 110°C for 1 h, the reaction was terminated by exposing the reaction mixture to air, thereby forming a fluorinated polymer brush poly(2 -perfluorooctylethyl methacrylate).

[0103] Such a plate was provided with a heating element according to Example ID and then used for welding according to Example IE.

[0104] Example 11: RAFT polymerization

[0105] A) surface initiation. The hot plate was activated and functionalized according to Examples 1A and IB. Next, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) was linked via the carboxyl group using 1 DMTMM at a concentration of 1 mg / ml in PBS at pH 7.0 to the amino groups on the plate. In another embodiment, the linker EDC was used to connect the amino and carboxyl groups.

[0106] B) polymerization. RAFT polymerization was carried out in a solution of monomer N,N- dimethylacrylamide (DMA) with the addition of a zinc tetraphenylporphyrin (ZnTPP) catalyst and in DMSO solvent in a weight ratio of 500: 1, using light irradiation at 405 nm, thereby forming polymer brushes of poly (acrylamide), with the advantage that the polymerization could be carried out in a normal atmosphere and at laboratory temperature.

[0107] In another embodiment, the plate was functionalized with 4-cyano-4- (phenylcarbonothioylthio)pentanoic acid, for photopolymerization of methyl methacrylate (MMA) and growth of a poly (methacrylate) polymer brush. Such a plate was provided with a heating element according to Example ID and then used for welding according to Example IE.

[0108] Example 12: Phosphonic acids as linkers

[0109] An aluminum hot plate was anodized in 10% (v / v) H2SO4 and a voltage of 20V was applied for 10 min. The substrate was then washed with distilled water. The plate was then incubated for 1 day in a 1 : 1 ethanol / water solution with 10 mM (aminomethyl)phosphonic acid (AMP A) at pH 5 and 40 °C. The substrate was then sonicated in ethanol / water and dried. After functionalization, a PEG polymer brush was prepared by grafting onto the surface according to Example 1C.

[0110] In another exemplary embodiment, the titanium plate was exposed to an oxygen plasma with a power of 100W for 10 min. In the next step, the plate was immersed in a 1 mM solution of 11-(2- bromoisobutyrate)-undecyl-l -phosphonic acid in anhydrous ethanol and left for 24 h at room temperature. After incubation, the plate was sonicated in ethanol and water for 10 minutes, and then the plate was dried with a stream of nitrogen. Next, a PEG polymer brush was prepared by grafting from the surface according to Example 10B. In another exemplary embodiment, a stainless steel plate was sonicated in acetone, ethanol, water for 10 minutes each, and after drying with a stream of nitrogen, placed in an ozone purifier for 1 hour. It was then placed in a solution of 4M styrene, 12mM CuBr, 25mM N,N,N,N,N- pentamethyldiethylenetriamine (PMDETA) in anisole degassed and heated to 90°C under argon, thereby crosslinking the poly(styrene) polymer brush. After polymerization, the plate was washed with methanol and dichloromethane. In another embodiment, polymerization in styrene was alternated with polymerization in methyl methacrylate, resulting in a block copolymer (PS-b-PMMA).

[0111] The plate was provided with a heating element according to Example ID and then used for welding according to Example IE, where the use of phosphonic acid instead of silane increased the possible temperature of use of the plate up to 350°C.

[0112] Example 13

[0113] The glass body of the hot plate was activated according to Example 1A. Then, a 1 ml vial with 100 pl of 1,3 -dichlorotetramethyldisiloxane (DCDMS) was placed in a desiccator for 10 min at room temperature and 20% humidity, when hydrolysis of the silane occurred. After deposition of a polymer brush of poly(dimethylsiloxane) (PDMS) on the body of the hot plate, the plate was sonicated in toluene and isopropanol for 5 min and dried using a nitrogen stream. In the next step, the brushes were methylated. The plate and 0.2 ml of chlorotrimethylsilane were placed in a desiccator for 1 hour. The plate was then sonicated again for 5 minutes in toluene and isopropanol. The plate was fitted with a heating element according to example ID and then used for welding according to example IE.

[0114] Example 14: Welding of plastics

[0115] The polymer brush-provided hot plates according to examples 1 to 13 were heated to various temperatures from 170 °C to 250 °C and a polypropylene polymer filled with glass fibers in a ratio of 5%, 10%, 20% (w / w) was always placed on the heated hot plate for 5 to 20 s, thereby melting 1 mm of material, then two pieces of the product were pressed together for 20 s using opposing holders. No traces of polypropylene were subsequently detected on the hot plate after welding of the glass fiber-filled polypropylene material.

[0116] In another embodiment, the plates were heated to temperatures of 150 to 220 °C for welding polyethylene and the polyethylene was applied to the plate for 20 seconds. No traces of polyethylene on the hot plate were subsequently detected after welding the material. In another embodiment, polyvinyl chloride was welded at temperatures of 170 to 220 °C with application to the hot plate for 30 seconds. No traces of polyvinyl chloride were subsequently detected on the hot plate after welding the material.

[0117] In another embodiment, polystyrene was welded at temperatures of 200 to 260 °C for 10 s to the plate. In another embodiment, acrylonitrile butadiene styrene was welded at temperatures of 230 to 260 °C for 15 s to the plate. For poly(methyl methacrylate), a temperature of 180 to 240 °C was used for 20 s at a pressure of 0.3 Pa. In another embodiment, polylactic acid was welded at temperatures of 160 to 180 °C for 0.3 Pa for 10 s to the plate. In another embodiment, thermoplastic polyurethane was welded at a temperature of 160 to 200 °C by applying 0.3 Pa to the plate for 15 s. Polyoxymethylene was welded at a temperature of 220 to 240 °C for 30 s. After welding the material, no traces of welded plastic were detected on the hot plate in any of these embodiments.

[0118] The polymer brush-provided hot plates of Examples 13 and 14 were heated to temperatures of 260 to 300 °C for welding polyethylene terephthalate, polycarbonate, nylon, for 30 s. In another embodiment, polyether ether ketone or PTFE was welded at a temperature of 350 to 400 °C for 1 to 2 minutes of contact with the hot plate. After welding the material, no traces of welded plastic were detected on the hot plate in any of these embodiments.

[0119] Example 15

[0120] The hot plate was constructed from a metal plate containing a heating coil as a heating element. Glass or metal hot plates with a polymer brush prepared according to Examples 1 to 13 are attached to this heating element on both sides by means of clips. To improve thermal conductivity, graphite paste can be applied between the heating element and the hot plate with a polymer brush to improve heat transfer. The hot plates attached in this way allow the simultaneous melting of two thermoplastic parts, which are then placed together for 20 to 30 seconds, thereby creating a weld. The pressure in the range of 0.01 to 0.5 MPa is provided by servomotors. Alternatively, the pressure can be provided manually by the operator, in another embodiment pneumatically.

[0121] Example 16

[0122] A hot metal plate was coated on both sides with a polymer brush according to example 2 or 12. It was attached to a linear slide and non-contact inductively heated in a docking position between two heating coils (alternatively, infrared irradiative heaters can be used). After reaching the required temperature, this plate was moved to the welding position, where the thermoplastic parts to be welded were pressed onto it from both sides. After the plastics had melted, these parts were moved apart, and the plate was moved to the docking position for re-heating, while the thermoplastics were pressed together by the jaws, thus completing the welding.

[0123] Example 17: Roughening of the hot plate surface by nanoparticles

[0124] The hot plate was roughened with nanoparticles. The aluminum plate was placed in a deposition chamber, heated to 300 to 600 °C, where aluminum nanoparticles with dimensions of 10 to 100 nm were deposited on it using a gaseous aggregation source of nanoparticles generated at a pressure of 40 to 60 Pa, using a 3 -inch magnetron at a DC power of 50 to 200 W for 1 to 100 minutes. The significantly lower sintering temperature of the nanoparticles below the melting point of the material led to the formation of a solid but rough nanostructure with an RMS roughness in the range of 10 nm to 1 pm. This structure was further exposed to O2 / H2 plasma at a power of 100 W for 10 minutes. In the next step, the plate was silanized and polymer chains were grafted according to examples IB, C. In another embodiment, chains were grafted according to Example 12. The roughened substrate covered with a polymer brush led to a reduction in the contact area with the welded material.

[0125] In another embodiment, titanium nanoparticles were used, deposited under the same conditions on a titanium substrate heated to 500 to 900 °C, or in another embodiment, SiCE nanoparticles were deposited on a glass plate, where a radiofrequency voltage of 100 W was used to produce the nanoparticles. In another embodiment, commercially available aluminum nanoparticles were applied by spin-coating to an aluminum plate, and were then sintered in a vacuum oven at a temperature of 400 °C.

[0126] Example 18: Hot plate with a conductive transparent layer

[0127] The hot plate contained a glass substrate covered with a layer of transparent conductive oxide (TCO), which was indium tin oxide (ITO). This TCO layer was activated with hydroxyl groups according to Example 1 A. In another embodiment, the substrate was covered with a layer of fluorine-doped tin oxide (FTO) and activated in the same way. In another embodiment, the glass substrate was covered with a layer of aluminum-doped zinc oxide (AZO). In all embodiments, the transparent oxide layer was conductive and also served as a heating element. In these embodiments, the result is a transparent hot plate, the possible damage or adhesion of plastic to the hot plate can be easily checked by optical measurement.

[0128] The optical measurement was carried out in such a way that during the welding of plastics, in the interval when the hot plate is moved between welding steps, the hot plate was illuminated by a light source and the image of the hot plate was captured by a camera. The obtained image is processed and evaluated in terms of damage or adhesion of pieces of plastic. In the event that the hot plate is damaged or a piece of plastic has adhered to it, the plate is serviced or replaced, and then welding is continued.

[0129] Example 19: Hot plate with reflective layer The hot plate was activated, silanized, and grafted with a polymer brush according to examples 1 A,B,C. Then, a metallic reflective layer of silver or aluminum was provided on the surface opposite to the surface provided with the polymer brush. The hot plate was further provided with a heating element according to example ID and used for welding according to example IE. The thus prepared plate was used for optical diagnostics of possible damage or contamination with adhered plastic, wherein the optical diagnostics is performed by reflection of a surface light source.

[0130] Example 20: Transparent hot plate, infrared heating

[0131] Two hot plates made of glass were activated, silanized, and grafted with a polymer brush according to examples 1A,B,C. Then these plates were mounted on each side on a flat heating element in the form of 10 halogen bulbs 10 cm long, so that the polymer brushes of both plates pointed away from the plate. The thus prepared plate was used for welding plastics. When the plastic product absorbed light radiation, while the plate kept the shape of the weld in a plane. In this example, it was possible to independently change the pressing force and polymer temperature due to the small heat absorption, capacity, and conductivity of the glass substrate of the plate. Power 500-1000W was applied for 5 -3 Os at the moment of contact of the welded product and the plate.

[0132] Example 21: Hot plate with light-absorption layer

[0133] An infrared absorbing layer selected from the group of diamond-like layer (DLC), titanium carbide, titanium carbide nitride, or zirconium carbide was applied to two glass plates, which was activated in O2 / H2 plasma, and then functionalized and grafted according to example IB, C, D. These plates were mounted on an infrared heating element, according to example 20. The DLC layer absorbed infrared radiation, which heated the top layer of the plate very quickly, even at a lower infrared heating power of 200 W to 700 W. In another embodiment, an infrared absorbing gradient layer of titanium carbidetitanium oxide or aluminum nitride-aluminum oxide was used, the top oxide layer was then provided with a polymer brush according to example 12. In another embodiment, an ITO layer, antimony tin oxide, tungsten oxide, vanadium oxide, chromium oxide, was used, which was activated, functionalized, and grafted according to example 1A,B,C. It was then provided with irradiative heating element and used for welding according to example 1D,E. In another embodiment, a layer of LaBg, titaniumaluminum nitride, titanium oxynitride was used, which was covered with a SiO2 layer, and activated, functionalized and grafted according to example 1A,B,C; further provided with a heating element and used for welding according to example 1D,E. In another embodiment, nanoparticles were deposited on the glass as an absorbing layer, for example metal nanoparticles (Al, Ti), or metal oxide nanoparticles (ITO, antimony tin oxide, tungsten oxide, vanadium oxide), or metal nitride (titanium -aluminum nitride, titanium oxynitride, aluminum nitride), these nanoparticles were sintered at a temperature below the melting point of the material, thereby creating a structure with a roughness of 5nm to 5 um, which was further functionalized with a polymer brush.

[0134] Example 22: Hot plate with carbon surface for direct polymerization

[0135] The surface of the hot plate contained carbon. Preferably, the surface was produced by depositing a thin layer using vapor phase deposition (PVD) and was selected from the group of the following hard materials: metal and metalloid carbides, namely Ti, Zr, W, Cr, V, Nb, Si, B, Ta, diamond-like layer (DLC), amorphous hydrocarbon layer (a-C:H), amorphous carbon layer (a-C) and amorphous carbon layer with metal (a-C:Me). Immediately after deposition, polymer brush layers were applied using: a) Benzophenone (C-H on the surface): To form the polymer brush, a 1% (w / v) solution of benzophenone in acetone or ethanol was prepared. The surface of the plate was then exposed to this solution for 1 minute. A monomer (e.g. acrylonitrile, methyl methacrylate, benzyl methacrylate, vinylidene fluoride, fluorinated methacrylate, perfluorooctyl acrylate, styrene, polyethylene glycol acrylate, poly(oligo(ethylene glycol) methyl ether methacrylate) was added at a concentration of 1-2 M. Then the surface was irradiated with a wavelength of 360 nm with an area power of 10-100 mW / cm2for 10 minutes to 1 hour. Or b) Diazonium (C on the surface): The plate with a carbon layer was placed in a solution of diazonium with a COOH group (5 mM 4-carboxyphenyldiazonium) in acetonitrile with the addition of a reducing agent (20 mM NazSOs), after 1 minute washed with acetonitrile and dried with nitrogen. Alternatively, electrografting was used instead of a reducing agent. This was carried out in an electrolyte of 0.1 M tetrabutylammonium tetrafluoroborate in acetonitrile, when the plate was used as a working electrode. The layer was deposited using 5 scans of cyclic voltammetry (-0.6V, +0.2V). The resulting aryl with a COOH group on the surface allowed the attachment of NFf-polymcr chains using EDC / NHS, ATRP initiator (N-(2-aminoethyl)-2-bromo-2-methylpropanamide) for polymerization according to example 10 or RAFT initiator (2-(dodecylthiocarbonothioylthio)-2 -methylpropionic acid) for polymerization according to example 11. Or c) Silanization, or carbodiimide (-OH, -COOH on the surface): The plate was treated in O2, or H2 / O2 plasma, or ozone, which allowed the formation of -OH or -COOH groups on the surface for the attachment of Si-ATRP or Si-RAFT initiators using silanization, or EDC / NHS, and polymerization from monomers according to examples 10 and / or 11.

Claims

CLAIMS1. A method for thermal welding of thermoplastics using a hot plate, said method comprising the steps of: a) heating the hot plate to a temperature required for welding the thermoplastics, and bringing the thermoplastics to be welded into contact with the hot plate until the areas of the thermoplastics to be welded melt, and b) removing the thermoplastics from the hot plate, joining the areas of the thermoplastics and pressing them together to weld them, characterized in that the hot plate body is made of a material selected from the group of metal, metalloid, metal oxide, metalloid oxide, metal nitride, metalloid nitride, metal oxynitride, ceramic and / or glass, and the hot plate is provided with a polymer brush on one or more surfaces intended for contact with the thermoplastics.

2. The method according to claim 1, wherein the hot plate comprises a layer of transparent conductive oxide between the hot plate body and the polymer brush, or in the hot plate body, preferably the material of the hot plate body is transparent, more preferably the material of the hot plate body is glass; and wherein the method comprises step c), in which the hot plate is after step a), simultaneously with step b) or after step b) inserted between a light source and a camera and the camera takes an image from which it is evaluated whether the surface of the hot plate is damaged or whether any welded thermoplastic has adhered to the surface of the hot plate.

3. The method according to claim 1, wherein the hot plate or a part thereof is transparent, and the transparent hot plate or a transparent part of the hot plate is provided with a metal reflective layer on the side opposite to the surface provided with the polymer brush; and wherein the method comprises step c), in which after step a), simultaneously with step b) or after step b) a light source and a camera are placed in the vicinity of the hot plate, so that the light source illuminates the hot plate and the camera scans the surface of the hot plate using the reflection of light from the light source, wherein the images from the camera are used to evaluate whether the surface of the hot plate is damaged or whether any welded thermoplastic has adhered to the hot plate surface.

4. A device for welding plastics, which comprises a hot plate and means for pressing thermoplastics together at the weld area, characterised in that the hot plate body is made of a material selected from the group of metal, metalloid, metal oxide, metalloid oxide, metal nitride, metalloid nitride, metal oxynitride, ceramic and / or glass, and the hot plate is provided with a polymer brush on one or more surfaces intended for contact with thermoplastics.

5. The device according to claim 4, wherein the device further comprises a heating element.

6. The device according to claim 4 or 5, wherein the surface of the hot plate body is treated by surface roughening, preferably in the range of units of nanometers to hundreds of microns.

7. The device according to any one of claims 4 to 6, wherein between the hot plate body and the polymer brush there is a coating layer for binding the polymer brush, preferably the coating is selected from the group of metal oxide, metalloid oxide, glass, siloxane, metal nitride, metalloid nitride, metal oxynitride and carbon-containing coating.

8. The device according to any one of claims 5 to 7, wherein the heating element is in thermal contact with the hot plate or the heating element is adapted to heat the hot plate without direct contact; preferably the heating element is selected from the group of resistance element, electromagnetic element, or lightradiation element.

9. The device according to any one of claims 4 to 8, wherein the hot plate is provided with a polymer brush on two opposite surfaces of the hot plate.

10. The device according to any one of claims 4 to 9, wherein the hot plate comprises a layer of transparent conductive oxide between the hot plate body and the polymer brush or in the hot plate body, preferably the material of the hot plate body is transparent, more preferably the material of the hot plate body is glass; and the device further comprises a light source and a camera arranged on opposite sides of the hot plate.

11. The device according to any one of claims 4 to 8, wherein the hot plate or a part thereof is transparent, and the transparent hot plate or a transparent part of the hot plate is provided with a metal reflective layer on the side opposite to the surface provided with the polymer brush; and the device further comprises a light source and a camera arranged on the side of the hot plate provided with the polymer brush.

12. The device according to any one of claims 4 to 8, wherein two hot plates with transparent bodies provided with a polymer brush are mounted on a light-radiation heating element, preferably a halogen or infrared heating element, which is located between the hot plates.

13. The device according to claim 12, wherein both hot plate bodies are covered with a layer absorbing radiation from the light-radiation heating element, wherein a polymer brush is bound to this absorbing layer.

14. A hot plate for use in the method according to claim 1, characterized in that the hot plate body is made of a material selected from the group consisting of aluminum, copper, an aluminum alloy and / or copper alloy, steel, chromium, glass, and the hot plate is provided with a polymer brush on one or more surfaces intended for contact with thermoplastics, and the hot plate is further provided with a heating element.

15. The hot plate according to claim 14, wherein the hot plate body is made of glass, and- the glass hot plate is provided with a layer of transparent conductive oxide as a heating element, said layer being located between the hot plate body and the polymer brush or in the hot plate body; and / or- the glass hot plate is provided on one side with a polymer brush, and on the side opposite to the side provided with the polymer brush, the hot plate is provided with a reflective metal layer.