Method for applying at least one silicone layer by laser transfer printing
阅读说明：本技术 通过激光转移印刷涂覆至少一个硅酮层的方法 (Method for applying at least one silicone layer by laser transfer printing ) 是由 克劳斯·埃勒尔 安德烈亚斯·克尔恩贝格尔 约翰尼斯·诺伊维尔特 于 2019-01-28 设计创作，主要内容包括：本发明涉及一种通过激光转移印刷施加至少一个硅酮层的方法,该方法适合于生产传感器、致动器和其他EAP层系统。在所述系统中硅酮层可以用作导电电极层或用作介电层。该方法可以设计成连续的并且可以与不同的其他涂覆技术结合。(The invention relates to a method for applying at least one silicone layer by laser transfer printing, which is suitable for producing sensors, actuators and other EAP layer systems. The silicone layer may be used as a conductive electrode layer or as a dielectric layer in the system. The method can be designed continuously and can be combined with various other coating techniques.)
1. A method of applying at least one silicone layer by laser transfer printing, the method comprising the steps of:
(i) providing a laser source (31);
(ii) providing a printing compound carrier (33) below the laser source (31), the printing compound carrier (33) being transparent to laser radiation and coated on the underside with a cross-linkable silicone composition (35), and at least the surface of the cross-linkable silicone composition being charged to an electric potential phi _ 1;
(iii) providing a deposition carrier (36) below the printing compound carrier (33);
(iv) providing an electrode (37) below the deposition carrier (36), the electrode (37) being charged to an electric potential phi _3, wherein phi _1 and phi _3 have opposite polarities;
(v) irradiating the printing compound carrier (33) with a laser beam (32) such that at least a portion of the cross-linkable silicone composition (35) is separated and transferred to the deposition carrier (36); and
(vi) Forming a silicone layer by fully or partially cross-linking the silicone composition (35) transferred to the deposition support (36).
2. The method according to claim 1, wherein at least the surface of the deposition support (36) facing the cross-linkable silicone composition (35) is charged to an electrical potential phi _2, wherein phi _2 and phi _1 have opposite polarities, and phi _2 is selected such that at least a portion of the amount of charge of the silicone composition (35) transferred to the deposition support (36) in step (v) is neutralized on the surface of the deposition support (36).
3. Method according to any one of claims 1 and 2, wherein an opaque separating layer (34) is provided between the printing compound carrier (33) and the silicone composition (35), the separating layer (34) being heated upon irradiation with the laser beam (32).
4. A method according to any one of claims 1 to 3, wherein the focal point (40) of the laser beam (32) is located above the printing compound carrier (33).
5. The method of any one of claims 1 to 4, wherein cone CP50-2 has an opening angle of 2 ° at 25 ℃ and a shear rate of 1s by a calibrated rheometer with a cone-plate system-1The silicone composition has a dynamic viscosity of 10 mPas or more and 1000 pas or less, measured according to DIN EN ISO 3219:1994 and DIN 53019.
6. The method according to any one of claims 1 to 5, wherein the silicone composition is an addition-crosslinking silicone composition and comprises the following components:
(A) an organic compound or organosilicon compound containing at least two groups having aliphatic carbon-carbon multiple bonds,
(B) an organosilicon compound containing at least two Si-bonded hydrogen atoms,
or instead of or in addition to (A) and/or (B)
(C) An organosilicon compound containing SiC-bonded radicals having aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms, and
(D) a hydrosilylation catalyst.
7. The method according to claim 6, wherein the addition-crosslinking silicone composition comprises the following further components:
(E) one or more fillers selected from the group consisting of: BET surface area of at least 50m2Fumed or precipitated silica, carbon black, activated carbon, graphite, graphene, diamond, carbon nanotubes, aluminum nitride, aluminum oxide, barium titanate, beryllium oxide, boron nitride, magnesium oxide, particulate metals, silicon carbide, tungsten carbide, zinc oxide, titanium dioxide, ferrites, NIR absorbing compounds,/gAbsorbents, MIR absorbents, and combinations of these fillers.
8. The method of any one of claims 1 to 7, wherein the silicone layer is a dielectric silicone layer or a conductive silicone layer.
9. The method according to any one of claims 1 to 8, wherein the silicone layer has a layer thickness of 0.1 to 200 μm, measured by scanning electron microscopy analysis.
10. The method according to any one of claims 1 to 9, wherein the printing compound carrier (33) is selected from the group consisting of: glass, vitreous silica, PET, polycarbonate, PMMA, and zinc selenide glass.
11. The method according to any one of claims 1 to 10, wherein the deposition carrier (36) is selected from the group consisting of: PET film, metal foil, and glass.
12. The method according to any one of claims 1 to 11, wherein the deposition carrier (36) additionally has the following: one or more crosslinked silicone layers, one or more layers of a crosslinkable silicone composition, a silicone multilayer composite having at least two layers of cured silicone, and a metal layer.
13. The method according to claim 12, wherein the individual layers have a thickness of 0.1 μm or more to 200 μm or less, measured in each case by scanning electron microscope analysis.
14. The method according to any one of claims 1 to 13, wherein the transferred silicone composition is laminated with a silicone film having a film thickness of 0.1 μ ι η to 200 μ ι η or a silicone multilayer composite having at least two layers of cured silicone each having a layer thickness of 0.1 μ ι η to 200 μ ι η, in each case measured by scanning electron microscope analysis.
15. Method according to claim 14, wherein the silicone membrane (55) is obtained by separation from a membrane support (19), said separation comprising the steps of:
-immersing the silicone film (55) coated on the carrier film (19) in a liquid bath (51) in the direction of the not yet separated silicone film and/or spraying the interior of the carrier film (19) that has been separated from the silicone film with a liquid by means of a spraying unit (54); and
-separating the silicone film from the laminating film.
16. The method of claim 15, wherein the weak point of the separated silicone membrane (55) is tested by a tuned puncture tester (24).
17. A method according to any one of claims 1 to 16, wherein one or more further silicone layers are applied to the transferred silicone composition by repeating steps (i) to (vi).
18. A method according to any one of claims 1 to 17, wherein the deposition carrier (36) is configured as a moving conveyor belt, which is supplied from a deposition carrier roll (2) and collected in a storage roll (3) after coating.
19. The method according to any one of claims 1 to 18, wherein the deposition carrier (36) is configured as a moving endless belt and is circulated via a belt store (18b) until the coating with one or more silicone layers is completed.
20. The method according to any one of claims 1 to 19, wherein the laser source (31) is arranged to roughen, ablate, structure and/or cut the surface of the deposition carrier (36) or the surface of the silicone layer applied thereon.
21. The method according to any one of claims 1 to 20, wherein the silicone layer is an electrically conductive silicone layer, and the method comprises the steps of:
-providing a dielectric layer (61);
-applying a conductive metal layer (62) to the dielectric layer (61);
-applying the conductive silicone layer (63) to the conductive metal layer (62);
-applying a further conductive metal layer (62) to the conductive silicone layer (63);
-applying a further dielectric layer (61) to the further conductive metal layer (62).
22. The method as claimed in claim 21, wherein the dielectric layers (61) each have a layer thickness of 5 μ ι η to 200 μ ι η, the electrically conductive metal layers (62) each have a layer thickness of 10nm to 100 μ ι η, and the electrically conductive silicone layer (63) has a layer thickness of 5 μ ι η to 200 μ ι η, in each case measured by scanning electron microscope analysis.
23. The method according to any one of claims 1 to 22, wherein the printing compound carrier (33) with the untransferred cross-linkable silicone composition (35) resulting from step (v) is completely coated again with the cross-linkable silicone composition (35) and used for applying one or more further silicone layers by laser transfer printing.
24. The method of claim 23, wherein the full coating comprises the steps of:
-separating the non-transferred silicone composition (35) from the printing compound carrier (33) by means of a carry-out system (44);
-treating the separated silicone composition (35) in a treatment system (45); and
-transporting the treated silicone composition (35) onto the printing compound carrier (33) by means of a loading system (43).
25. The method according to any of claims 1 to 24, wherein the method is a method for manufacturing a sensor, an actuator or an EAP layer system.
26. The method according to claim 25, wherein the silicone layer is used as an electrode layer and/or as a dielectric layer in the sensor, actuator or EAP layer system.
Background
Various methods for producing silicone layers and/or systems based on silicone layers are known in the prior art.
DE 19644112 a1 describes a continuous process for producing cast films of silicone rubber. In this method, a two-component silicone compound is cast on an endless belt in a corresponding thickness and width. The introduction of heat from the heating system produces heat activated curing on the endless belt. Upon curing, the film is removed from the circulating belt, further heat treated, and finally rolled up.
WO 2014/090506 a1 describes a method for the continuous production of thin silicone films of uniform film thickness, and also describes silicone films produced by this method and their use. In this case, the silicone compound is extruded through a slot die (slot die) onto a conveyor belt (carrier belt) and cured. When the film is cured, it can be removed from the conveyor or rolled up with the conveyor.
WO 2015/113911 a1 describes a method for producing a multilayer composite having at least two thin silicone layers of uniform layer thickness.
US 2016/0057835 a1 describes the production of electroactive layer systems and assemblies. In connection therewith, a method and a procedure for producing a laminar electrode (conductive layer) on a non-conductive layer are described. In addition, use with electrochemical fillers or layers is mentioned.
US 2016/156066 a1 describes a method of modifying a thin polymer layer with different dopants by vapor deposition (i-CVD). Here, in a vacuum operation, the polymer together with the variable dopant is deposited uniformly and very thinly on any desired surface or geometry.
WO 2014/187976 a1 describes a method of producing an elastomer-based film stack actuator by a continuous lamination process (dry deposition in a roll-to-roll process). The laminate is produced by previously separating the elastomer film from the support and the laminate film, depositing it on another elastomer film printed with the electrode material, and repeating these steps a plurality of times.
DE 102014005851 a1 describes an apparatus and a continuous stacking method for producing an elastomer stack actuator. The method is limited to providing precise lamination of the already coated electrode-elastomer film composite. Repeated lamination processes multiple times using endless conveyor belts or continuous feeds result in the construction of a multilayer structure. The laminar flow accuracy is achieved by means of a regulating unit and a photosensor technology. After each lamination step, the electrodes are contacted by making vias, which are filled with a contact material.
WO 2014/074554 a2 describes a method for producing a multilayer, stacked electroactive transducer in a cyclic operation. Two separate rolls provide an ultra-thin film of electroactive polymer, previously separated from the conveyor belt, to a continuous lamination step. The whole operation also comprises a printing station of the electrodes and the application of the adhesive before the respective lamination step.
DE 102014003357 a1 describes a method for producing surface-modified silicone layers. In this method, conductive particles (carbon black, CNT, silver nanoparticles) are applied to a non-crosslinked silicone layer and then cured in a composite system. The method for applying the particles involves mechanical application involving partial penetration into the silicone surface.
Known methods for applying silicone layers, in particular those suitable for producing electrode layers and/or dielectric layers in actuators, sensors and other electroactive polymer layer systems, are limited in their variability, application accuracy, throughput and later robustness (robustness) and achieved component effectiveness.
Drawings
Fig. 1 shows a roll-to-roll process diagram for producing a multilayer silicone elastomer system.
FIG. 2 shows a process diagram for producing a multilayer silicone elastomer system using an endless belt.
Fig. 3 shows a diagram of a laser transfer operation.
Figure 4 shows a diagram relating to the application of a silicone composition to a printing compound carrier suitable for laser transfer printing.
Figure 5 shows a diagram of the mechanism for separating a silicone membrane from a membrane support using a liquid.
Fig. 6 shows the configuration of the composite electrode.
Detailed Description
The invention relates to a method for applying at least one silicone layer by laser transfer printing, comprising the following steps:
(i) Providing a laser source;
(ii) providing a printing compound carrier below the laser source, which printing compound carrier is transparent to the laser radiation and is coated on the underside with a cross-linkable silicone composition, and at least the surface of which cross-linkable silicone composition is charged to a potential phi _ 1;
(iii) providing a deposition support beneath the printing compound support;
(iv) providing an electrode under the deposition carrier, the electrode being charged to a potential phi _3, wherein phi _1 and phi _3 have opposite polarities;
(v) irradiating the printing compound support with a laser beam such that at least a portion of the cross-linkable silicone composition separates and transfers to the deposition support; and
(vi) the silicone layer is formed by fully or partially crosslinking the silicone composition transferred to the deposition support.
In the context of the present invention, phi denotes Φ.
The base materials which can be used for the silicone layer include in principle all silicone compositions known from the prior art. The silicone composition is preferably selected such that its crosslinking has not been triggered by the laser irradiation used for laser transfer printing. The composition is preferably a silicone elastomer composition.
The silicone elastomer composition used may be, for example, an addition-crosslinking, peroxide-crosslinking, condensation-crosslinking or radiation-crosslinking composition. Peroxidic crosslinking or addition crosslinking compositions are preferred. Addition-crosslinking compositions are particularly preferred.
The silicone elastomer composition may have a one or two component formulation. The silicone elastomer composition is crosslinked by the supply of heat, by ultraviolet light and/or by moisture. Suitable examples are the following silicone elastomer compositions: HTV (addition crosslinking), HTV (radiation crosslinking), LSR, RTV 2 (addition crosslinking), RTV 2 (condensation crosslinking), RTV 1, TPSE (thermoplastic silicone elastomer), thiol-ene and cyanoacetamide crosslinking systems.
The addition-crosslinking silicone composition comprises, in its simplest form:
(A) at least one linear compound containing groups having aliphatic carbon-carbon multiple bonds,
(B) at least one linear organopolysiloxane compound having Si-bonded hydrogen atoms, either in place of or in addition to (A) and (B)
(C) At least one linear organopolysiloxane compound comprising SiC-bonded groups having aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms, and
(D) at least one hydrosilylation catalyst (hydrosilylation catalyst).
In a particular embodiment, the silicone composition is a silicone elastomer composition having fluorinated side groups, for example as described in WO 2018/177523 a 1. In this embodiment, components (a), (B) and/or (C) preferably comprise at least 2.5 mol%, more preferably at least 5 mol% of fluorinated side groups, such as for example 3,3, 3-trifluoropropylmethylsiloxy and/or bis (3,3, 3-trifluoropropyl) siloxy.
The silicone composition may be a one-component silicone composition and a two-component silicone composition. In the latter case, the two components of the composition of the invention may comprise all the ingredients in any desired combination, generally with the proviso that one component cannot comprise simultaneously the siloxane having aliphatic multiple bonds, the siloxane having silicon-bonded hydrogen and the catalyst, in other words not substantially simultaneously the ingredients (a), (B) and (D) or (C) and (D).
The compounds (a) and (B) and/or (C) used in the composition of the invention are generally chosen so that crosslinking can be carried out. For example, compound (a) comprises at least two aliphatically unsaturated groups and (B) at least three Si-bonded hydrogen atoms, or compound (a) comprises at least three aliphatically unsaturated groups and siloxane (B) at least two Si-bonded hydrogen atoms, or, instead of compounds (a) and (B), siloxane (C) is used, which comprises aliphatically unsaturated groups and Si-bonded hydrogen atoms in the above-mentioned ratios. Also suitable are mixtures of (A) and (B) and (C) having the above-mentioned proportions of aliphatically unsaturated groups and Si-bonded hydrogen atoms.
The compounds (a) used according to the invention may comprise silicon-free organic compounds which preferably have at least two aliphatically unsaturated groups, and organosilicon compounds which preferably have at least two aliphatically unsaturated groups, or mixtures thereof.
Examples of silicon-free organic compounds (A) are 1,3, 5-trivinylcyclohexane, 2, 3-dimethyl-1, 3-butadiene, 7-methyl-3-methylene-1, 6-octadiene, 2-methyl-1, 3-butadiene, 1, 5-hexadiene, 1, 7-octadiene, 4, 7-methylene-4, 7,8, 9-tetrahydroindene, methylcyclopentadiene, 5-vinyl-2-norbornene, bicyclo [2.2.1]Hepta-2, 5-diene, 1, 3-diisopropenylbenzene, vinyl-containing polybutadiene, 1, 4-divinylcyclohexane, 1,3, 5-triallylbenzene, 1,3, 5-trivinylbenzene, 1,2, 4-trivinylcyclohexane, 1,3, 5-triisopropenylbenzene, 1, 4-divinylbenzene, 3-methylhepta-1, 5-diene, 3-phenylhex-1, 5-diene, 3-vinylchex-1, 5-diene and 4, 5-dimethyl-4, 5-diethyloct-1, 7-diene, N’Methylenebisacrylamide, 1,1, 1-tris (hydroxymethyl) propane triacrylate, 1,1, 1-tris (hydroxymethyl) propane trimethacrylate, tripropylene glycol diacrylate, diallyl ether, diallyl amine, diallyl carbonate, N’Diallyl urea, triallylamine, tris (2-methallyl) amine, 2,4, 6-triallyloxy-1, 3, 5-triazine, triallyl-s-triazine-2, 4,6(1H,3H,5H) -trione, diallyl malonate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, poly (propylene glycol) methacrylate.
As component (a), the silicone composition of the invention preferably comprises at least one aliphatically unsaturated organosilicon compound, in which case it is possible to use all aliphatically unsaturated organosilicon compounds hitherto used in addition-crosslinking compositions, such as, for example, silicone block copolymers having urea segments, silicone block copolymers having amide segments and/or imide segments and/or ester-amide segments and/or polystyrene segments and/or silarylene segments and/or carborane segments, and silicone graft copolymers having ether groups.
The organosilicon compounds (A) used which have SiC-bonded groups and aliphatic carbon-carbon multiple bonds are preferably linear or branched organopolysiloxanes comprising units of the general formula (I)
R4 aR5 bSiO(4-a-b)/2(I)
Wherein
R4Identical or different at each occurrence, independently an organic or inorganic radical free of aliphatic carbon-carbon multiple bonds,
R5identical or different at each occurrence, is independently a monovalent, substituted or unsubstituted SiC-bonded hydrocarbon radical having at least one aliphatic carbon-carbon multiple bond,
a is 0, 1, 2 or 3, and
b is 0, 1 or 2.
With the proviso that the sum of a + b is less than or equal to 3 and at least 2 radicals R per molecule5。
Radical R4Monovalent or polyvalent groups may be included, in which case polyvalent groups, such as divalent, trivalent and tetravalent groups, for example siloxy units of formula (I) to which two or more, such as two, three or four, are attached to each other.
R4Other examples of (a) are monovalent radicals-F, -Cl, -Br, -OR6-CN, -SCN, -NCO and SiC-bonded, substituted or unsubstituted hydrocarbon radicals which may be interrupted by oxygen atoms or groups-C (O) -and Si-bonded divalent radicals on both sides according to formula (I). If the radical R is4Containing SiC-bonded substituted hydrocarbon groups, the preferred substituents are halogen atoms, phosphorus-containing groups, cyano groups, -OR6、-NR6-、-NR6 2、-NR6-C(O)-NR6 2、-C(O)-NR6 2、-C(O)R6、-C(O)OR6、-SO2-Ph and-C6F5. In this case, R6The same or different at each occurrence, independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and Ph is phenyl.
Radical R4Examples of (A) are alkyl radicals, such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl radical, hexyl radicals, such as the n-hexyl radical, heptyl radicals, such as the n-heptyl radical, octyl radicals, such as the n-octyl radical, and isooctyl radicals, such as the 2,2, 4-trimethylpentyl radical, nonyl radicals, such as the n-nonyl radical, decyl radicals, such as the n-decyl radical, dodecyl radicals, such as the n-nonyl radical, dodecylN-dodecyl and octadecyl radicals, such as the n-octadecyl radical, cycloalkyl radicals, such as the cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals, aryl radicals, such as the phenyl, naphthyl, anthracenyl and phenanthrenyl radicals, alkylaryl radicals, such as the o-, m-and p-tolyl radicals, xylyl radicals and ethylphenyl radicals, and aralkyl radicals, such as the benzyl, α -and β -phenylethyl radicals.
Substituted radicals R4Examples of (A) are haloalkyl groups, such as the 3,3, 3-trifluoro-n-propyl group, the 2,2,2,2 ', 2 ', 2 ' -hexafluoroisopropyl group, the heptafluoroisopropyl group, haloaryl groups, such as the o-, m-and p-chlorophenyl groups, - (CH)2)-N(R6)C(O)NR6 2、-(CH2)n-C(O)NR6 2、-(CH2)o-C(O)R6、-(CH2)o-C(O)OR6、-(CH2)o-C(O)NR6 2、-(CH2)-C(O)-(CH2)pC(O)CH3、-(CH2)-O-CO-R6、-(CH2)-NR6-(CH2)p-NR6 2、-(CH2)o-O-(CH2)pCH(OH)CH2OH、-(CH2)o(OCH2CH2)pOR6、(CH2)o-SO2-Ph and (CH)2)o-O-C6F5Wherein R is6And Ph corresponds to the definition indicated above for it, and o and p are the same or different integers from 0 to 10.
R as a Si-bonded divalent radical on both sides according to formula (I)4Examples of (A) are derivatives from the above for the radical R with additional bonds which occur as a result of substitution by hydrogen atoms4The groups of the monovalent examples set forth; an example of such a group is- (CH)2)-、-CH(CH3)-、-C(CH3)2-、-CH(CH3)-CH2-、-C6H4-、-CH(Ph)-CH2-、-C(CF3)2-、-(CH2)o-C6H4-(CH2)o-、-(CH2)o-C6H4-C6H4-(CH2)o-、-(CH2O)p、(CH2CH2O)o、-(CH2)o-Ox-C6H4-SO2-C6H4-Ox-(CH2)o-, where x is 0 or 1 and Ph, o and p have the above definitions.
Preferably, the group R4Comprising monovalent, SiC-bonded, optionally substituted hydrocarbon radicals having from 1 to 18 carbon atoms and free of aliphatic carbon-carbon multiple bonds, more preferably monovalent, SiC-bonded hydrocarbon radicals having from 1 to 6 carbon atoms and free of aliphatic carbon-carbon multiple bonds, and more particularly methyl or phenyl radicals.
A radical R of the formula (I)5Any desired group suitable for addition reaction (hydrosilylation) with an SiH-functional compound may be included. If the radical R is5Containing SiC-bonded substituted hydrocarbon groups, the preferred substituents are halogen atoms, cyano groups and-OR 6Wherein R is6Having the above definition.
Preferably, the group R5Alkenyl and alkynyl groups having from 2 to 16 carbon atoms, such as vinyl, allyl, methallyl, 1-propenyl, 5-hexenyl, ethynyl, butadienyl, hexadienyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, vinylcyclohexylethyl, divinylcyclohexylethyl, norbornenyl, vinylphenyl and styryl, particular preference being given to using vinyl, allyl and hexenyl groups.
The molecular weight of component (A) can vary within a wide range, for example 102To 106g/mol. Thus, for example, component (A) may comprise a relatively low molecular weight alkenyl-functional oligosiloxane, such as 1, 2-divinyltetramethyldisiloxane, but may also be a highly polymeric polydimethylsiloxane, such as having a molecular weight of 105g/mol (number average molecular weight determined by NMR), with an intrachain or terminal Si-bonded vinyl group. The structure of the molecules forming component (a) is also not fixed; in particular, the structure of siloxanes of relatively high molecular mass, in other words oligomeric orThe polymeric siloxane may be in the form of a linear, cyclic, branched or resinous network. The linear and cyclic polysiloxanes are preferably of the formula R 4 3SiO1/2、R5R4 2SiO1/2、R5R4SiO1/2And R4 2SiO2/2Wherein R is4And R5Having the above definition. The branched and network polysiloxanes additionally comprise trifunctional and/or tetrafunctional units, preferably of the formula R4SiO3/2、R5SiO3/2And SiO4/2Those of (a). It will be appreciated that it is also possible to use mixtures of different siloxanes meeting the criteria of component (A).
Particular preference is given to using as component (A) a vinyl-functional, substantially linear polydiorganosiloxane, in each case using a calibrated rheometer with a cone/plate system at 25 ℃, a cone CP50-2, an opening angle of 2 DEG and a shear rate of 1s-1The viscosity is from 0.01 to 500000 pas, more preferably from 0.1 to 100000 pas, measured in accordance with DIN EN ISO 3219:1994 and DIN 53019.
As organosilicon compounds (B), it is possible to use all hydrogen-functional organosilicon compounds which have hitherto also been used in addition-crosslinkable compositions.
The organopolysiloxanes (B) used having silicon-bonded hydrogen atoms are preferably linear, cyclic or branched organopolysiloxanes composed of units of the formula (III)
R4 cHdSiO(4-c-d)/2(III)
Wherein
R4Has the above-mentioned definition, and can be used for making various foods,
c is 0, 1, 2 or 3, and
d is 0, 1 or 2,
with the proviso that the sum of c + d is less than or equal to 3 and that there are at least two Si-bonded hydrogen atoms per molecule.
The organopolysiloxanes (B) used according to the invention preferably contain Si-bonded hydrogen in an amount of from 0.04 to 1.7% by weight, based on the total weight of the organopolysiloxanes (B).
The molecular weight of component (B) can likewise vary within a relatively wide range, for example 102To 106g/mol. Thus, ingredient (B) may comprise, for example, a relatively low molecular weight SiH functional low polysiloxane, such as tetramethyldisiloxane, or alternatively may comprise a silicone resin having SiH groups or a high polymeric polydimethylsiloxane having SiH groups in-chain or terminal.
The structure of the molecules forming component (B) is also not fixed; in particular, the structure of the relatively high molecular mass SiH-containing siloxanes, in other words oligomeric or polymeric, may be a linear, cyclic, branched or resinous network. The linear and cyclic polysiloxanes (B) are preferably of the formula R4 3SiO1/2、HR4 2SiO1/2、HR4SiO2/2And R4 2SiO2/2Wherein R is4Having the above definition. Branched and network polysiloxanes additionally comprise trifunctional and/or tetrafunctional units, preferably of the formula R4SiO3/2、HSiO3/2And SiO4/2Wherein R is4Having the above definition.
It will be appreciated that it is also possible to use mixtures of different siloxanes meeting the criteria of component (B). In particular, the molecules forming component (B) may at the same time optionally contain, in addition to the necessary SiH groups, aliphatically unsaturated groups. Particular preference is given to using low molecular mass SiH-functional compounds, such as tetrakis (dimethylsiloxy) silane and tetramethylcyclotetrasiloxane, and higher molecular mass SiH-containing siloxanes, such as poly (hydroxymethyl) siloxane and poly (dimethylhydroxymethyl) siloxane, using a calibrated rheometer with a cone/plate system, a cone CP50-2, an opening angle of 2 DEG, and a shear rate of 1s -1Viscosity at 25 ℃ of 10 to 20000 mPas, measured according to DINEN ISO 3219:1994 and DIN 53019, or similar SiH-containing compounds, some of the methyl groups of which have been substituted by 3,3, 3-trifluoropropyl or phenyl groups.
In the crosslinkable silicone composition of the present invention, the amount of the component (B) is preferably such that the molar ratio of SiH groups to the aliphatic unsaturated groups (a) is from 0.1 to 20, more preferably from 0.3 to 2.0.
The components (A) and (B) used according to the invention are commercial products and/or can be prepared by customary methods.
Instead of components (a) and (B), the silicone composition of the invention may comprise an organopolysiloxane (C) having both aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms. The silicone composition of the invention may also comprise all three components (a), (B) and (C).
If siloxanes (C) are used, those which are concerned are preferably composed of units of the formulae (IV), (V) and (VI)
R4 fSiO4/2(IV)
R4 gR5SiO3-g/2(V)
R4 hHSiO3-h/2(VI)
Wherein
R4And R5With the definitions indicated above for them,
f is 0, 1, 2 or 3,
g is 0, 1 or 2, and
h is 0, 1 or 2,
with the proviso that there are at least two radicals R per molecule5And at least two Si-bonded hydrogen atoms.
Examples of organopolysiloxanes (C) are those comprising SiO4/2、R4 3SiO1/2、R4 2R5SiO1/2And R4 2HSiO1/2Those of the units, known as MP resins, and these resins may additionally contain R 4SiO3/2And R4 2SiO unit, and consisting essentially of R4 2R5SiO1/2、R4 2SiO and R4Straight-chain organopolysiloxanes of HSiO units, in which R is4And R5Satisfying the above definition.
The organopolysiloxanes (C) preferably have an average viscosity of from 0.01 to 500000 Pa.s, more preferably from 0.1 to 100000 Pa.s, in each case at 25 ℃ in accordance with DIN EN ISO 3219:1994 and DIN 53019, using a calibrated rheometer with a cone/plate system, cone CP50-2, opening angle 2 DEG, shear rate 1s-1And (4) measuring.
The organopolysiloxane (C) is commercially available or prepared by a usual method.
The addition-crosslinked silicone composition of the present invention may be selected from the group comprising:
-at least one of each of the compounds (A), (B) and (D),
at least one of each of the compounds (C) and (D), and
-at least one of each of the compounds (A), (B), (C) and (D),
wherein the definition is as follows:
(A) an organic compound or organosilicon compound containing at least two groups having aliphatic carbon-carbon multiple bonds,
(B) an organosilicon compound containing at least two Si-bonded hydrogen atoms,
(C) an organosilicon compound containing SiC-bonded radicals having aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms, and
(D) a hydrosilylation catalyst.
The silicone composition generally comprises from 30 to 95 wt%, preferably from 30 to 80 wt%, and more preferably from 40 to 70 wt% of (a), based on the total mass of the silicone composition.
The silicone composition generally contains 0.1 to 60 wt%, preferably 0.5 to 50 wt%, and more preferably 1 to 30 wt% of (B), based on the total mass of the silicone composition.
If the silicone composition does contain component (C), there is generally 30 to 95% by weight, preferably 30 to 80% by weight, more preferably 40 to 70% by weight of (C) in the formulation, based on the total mass of the silicone composition.
The amount of component (D) may be from 0.1 to 1000 parts per million (ppm), from 0.5 to 100ppm, or from 1 to 25ppm of a platinum group metal, depending on the total weight of the components.
The amounts of all components present in the silicone composition are selected such that their sum does not exceed 100 wt%, based on the total mass of the silicone composition.
As hydrosilylation catalyst (D), it is possible to use all catalysts known from the prior art. Component (D) may be a platinum group metal, such as platinum, rhodium, ruthenium, palladium, osmium, or iridium, or an organometallic compound or a combination thereof. Examples of component (D) are compounds such as hexachloroplatinic (IV) acid, platinum dichloride, platinum acetylacetonate and complexes of said compounds encapsulated in a matrix or core/shell-like structure. The platinum complex of organopolysiloxane having low molecular weight includes 1, 3-divinyl-1, 1,3, 3-tetramethyldisiloxane complex with platinum. Further examples are platinum phosphite complexes, platinum phosphine complexes or alkyl platinum complexes. These compounds may be encapsulated within a resin matrix.
The concentration of component (D) used to catalyze the hydrosilylation reaction of components (a) and (B) upon exposure is sufficient to generate the required heat in the process described herein. The amount of component (D) may be from 0.1 to 1000 parts per million (ppm), from 0.5 to 100ppm, or from 1 to 25ppm of a platinum group metal, depending on the total weight of the components. If the platinum group metal component is less than 1ppm, the curing rate may be low. The use of platinum group metals in amounts greater than 100ppm is uneconomical or reduces the stability of the adhesive formulation.
The silicone composition preferably comprises a platinum complex of the formula (VII)
R3 3Pt{CpR4 5-r-t[(CR2)nSiR1 oR2 p]t[SiR7 sR8 3-s]r} (VII),
Wherein in formula (VII)
Cp represents a cyclopentadienyl group and is a cyclopentadienyl group,
n is an integer of 1 to 8,
o is 0, 1, 2 or 3,
p is 0, 1, 2 or 3, with the proviso that o + p is 3,
r is 1, 2, 3, 4 or 5, preferably 1, 2 or 3, more preferably 1 or 2, more particularly 1,
t is 0, 1, 2, 3 or 4, preferably 0 or 1, more preferably 1, provided that r +
s is 0, 1 or 2, preferably 2,
r may be the same or different and represents a hydrogen atom or a monovalent, unsubstituted or substituted hydrocarbon group,
R1may be the same or different and represents a monovalent, unsubstituted or substituted hydrocarbon radical which may be interrupted by heteroatoms,
R2may be the same or different and represent a hydrolyzable group or siloxy group attached through an oxygen,
R7Which may be identical or different, and denotes a monovalent, unsubstituted or substituted, aliphatic saturated hydrocarbon radical which may be interrupted by heteroatoms, or denotes an oxygen-bonded siloxy group,
R8may be the same or different and are aliphatically unsaturated, optionally substituted radicals,
R3may be the same or different and represents a monovalent, unsubstituted or substituted aliphatic saturated hydrocarbon group,
R4may be the same or different and represents a hydrogen atom, a SiC-bonded silyl group or an unsubstituted or substituted hydrocarbon group which may be interrupted by heteroatoms.
Examples of such platinum complexes of the formula (VII) are
Trimethyl [ (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (((2-methylallyl) dimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (trimethoxysilyl) methyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (2-trimethoxysilyl) ethyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (3-trimethoxysilyl) propyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (3-dimethoxymethylsilyl) propyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (4-trimethoxysilyl) butyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (2-trimethoxysilyl) -1-methylethyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (3-trimethoxysilyl) -2-methyl-2-propyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ bis (2-methylallyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (trimethoxysilyl) methylbis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (2-trimethoxysilyl) ethyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (3-trimethoxysilyl) propyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (4-trimethoxysilyl) butyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (2-trimethoxysilyl) -1-methylethyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (3-trimethoxysilyl) -2-methyl-2-propyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ tris (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (triethoxysilyl) methyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (triacetoxysilyl) methyl- (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (3-bis-trimethylsiloxy) methylsilylpropyl ] (allyldimethylsilyl) cyclopentylplatinum (IV) ],
Trimethyl [ (3-triethoxysilyl) propyl- (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (triethoxysilyl) methyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Trimethyl [ (3-triethoxysilyl) propyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Trimethyl [ (triethoxysilyl) methyl-tris (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Triethyl [ (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) ],
Tris (trimethylsilylmethyl) [ (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Triethyl [ (trimethoxysilyl) methyl (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Triethyl [ (trimethoxysilyl) methyl-bis (allyldimethylsilyl) cyclopentadienyl ] platinum (IV),
Triethyl [ tris (allyldimethylsilyl) cyclopentadienyl ] platinum (IV) and
triethyl [ (trimethoxysilyl) methyltris (allyldimethylsilyl) cyclopentadienyl ] platinum (IV).
These platinum complexes are described, for example, in WO 2016/030325A 1.
In another embodiment, the silicone composition is a peroxide crosslinkable silicone material. These silicone materials can be organically crosslinked by addition of organic peroxides (as component D). In this case, the silicone composition consists at least of components (a) and (D). In that case, component (D) is preferably present in an amount of 0.1 to 20% by weight in the silicone rubber material of the invention. As component (D), crosslinking agents which may be used include all typical peroxides according to the prior art. Examples of component (D) are dialkyl peroxides, such as 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane, 1-di (tert-butylperoxy) cyclohexane, 1-di (tert-butylperoxy) -3,3, 5-trimethylcyclohexane, alpha-hydroxyperoxy-alpha' -hydroxy Dicyclohexyl peroxide, 3, 6-dicyclohexylidene-1, 2,4, 5-tetracyclooxyethane, di-tert-butyl peroxide, tert-butyl tert-triptycenyl peroxide and tert-butyl triethyl-5-methyl peroxide, diaralkyl peroxides, e.g. dicumyl peroxide, alkyl aralkyl peroxides, e.g. tert-butylcumyl peroxide and alpha, alpha’Di (tert-butylperoxy) -m/p-diisopropylbenzene, alkylacyl peroxides, such as tert-butyl perbenzoate, and diacyl peroxides, such as dibenzoyl peroxide, bis (2-methylbenzoyl peroxide), bis (4-methylbenzoyl peroxide), and bis (2, 4-dichlorobenzoyl peroxide). Vinyl-specific peroxides are preferably used, the main representatives of these being dialkyl and diaralkyl peroxides. Particular preference is given to using 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane and dicumyl peroxide. It is possible to use individual peroxides or mixtures of different peroxides. The amount of component (D) in the peroxidically crosslinkable silicone rubber material is preferably from 0.1 to 5.0% by weight, more preferably from 0.5 to 1.5% by weight. Preference is therefore given to crosslinkable silicone rubber materials according to the invention, characterized in that the crosslinking agent (D) is present in a range from 0.1 to 5.0% by weight and denotes an organic peroxide or a mixture of organic peroxides, in each case based on the total mass of the silicone composition.
The described materials can optionally comprise all further adjuvants which have hitherto also been used for the production of oxidizable compound-crosslinked and addition-crosslinkable compositions.
These adjuvants may also be added to all condensation-crosslinking silicone elastomer compositions known from the prior art. A more detailed description of the type of crosslinking is described, for example, in EP 0787766 a 1.
Examples of optional components include, inter alia, (E) fillers.
An example of a reinforcing filler that can be used as a component in the silicone composition of the invention is a silicone composition having at least 50m2Fumed or precipitated silicas with BET surface areas of,/g, and carbon blacks and activated carbons, such as furnace blacks and acetylene blacks, preferably with BET surface areas of at least 50m2Gas phase per gram and precipitated silica. The above-mentionedThe silica filler may have hydrophilic properties or may be made hydrophobic by known methods. The amount of active reinforcing filler in the crosslinkable composition is from 0 to 70% by weight, preferably from 0 to 50% by weight, based on the total mass of the silicone composition.
Particularly preferably, the crosslinkable silicone rubber material is characterized in that the filler (E) is surface-treated. The surface treatment is obtained by methods known in the art for hydrophobicizing finely divided fillers. The hydrophobization can be carried out, for example, by the in situ process, before incorporation into the polyorganosiloxane or in the presence of the polyorganosiloxane. Both processes can be carried out both in batch operation and in continuous form. The hydrophobizing agents preferably used are organosilicon compounds which are capable of reacting with the filler surface to form covalent bonds or permanently physically adsorbed on the filler surface. Examples of hydrophobicizers are alkylchlorosilanes, such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, octyltrichlorosilane, octadecyltrichlorosilane, octylmethyldichlorosilane, octadecylmethyldichlorosilane, octyldimethylchlorosilane, octadecyldimethylchlorosilane and tert-butyldimethylchlorosilane; alkylalkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane and trimethylethoxysilane; trimethylsilanol; cyclic diorgano (poly) siloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane; linear diorganopolysiloxanes such as dimethylpolysiloxanes having trimethylsiloxy end groups, and dimethylpolysiloxanes having silanol or alkoxy end groups; disilazanes, such as hexaalkyldisilazane, especially hexamethyldisilazane, divinyltetramethyldisilazane, bis (trifluoropropyl) tetramethyldisilazane; cyclic dimethylsilanes such as hexamethylcyclotrisilazane. Mixtures of the hydrophobicizing agents described above may also be used. To accelerate the hydrophobization, catalytically active additives, such as amines, metal hydroxides and water, are optionally also added.
Hydrophobization can be accomplished, for example, using one hydrophobizing agent or a mixture of two or more hydrophobizing agents in one step, or using one or more hydrophobizing agents in two or more steps.
As a result of the surface treatment, the carbon content of the preferred fillers (E) is at least 0.01 and up to 20% by weight, preferably from 0.1 to 10% by weight, more preferably from 0.5 to 5% by weight, based on the total mass of the silicone composition. Particularly preferred are those crosslinkable silicone rubber materials, characterized in that the filler (E) is a surface-treated silica having from 0.01 to 2% by weight, based on the total mass of the filler, of Si-bonded aliphatic unsaturated groups. These groups are, for example, Si-bonded vinyl groups. In the silicone rubber material of the invention, component (E) is preferably used alone or also preferably in the form of a mixture of two or more finely divided fillers.
The silicone composition of the invention may alternatively comprise as an ingredient a fraction of up to 70 wt%, preferably from 0.0001 to 40 wt%, based on the total mass of the silicone composition, of a further additive. These additives may be, for example, inert fillers, resinous polyorganosiloxanes different from the siloxanes (A), (B) and (C), reinforcing and non-reinforcing fillers, fungicides, fragrances, rheological additives, corrosion inhibitors, oxidation inhibitors, light stabilizers, flame retardants and agents influencing the electrical properties, dispersing aids, solvents, adhesion promoters, pigments, dyes, plasticizers, organic polymers, heat stabilizers and the like. These include additives such as finely ground quartz, diatomaceous earth, clays, chalk, lithopone (lithopone), carbon black, graphite, graphene, metal oxides, metal carbonates, metal sulfates, metal salts of carboxylic acids, metal dusts, fibers, nanofibers such as glass fibers, polymer powders, dyes, pigments, and the like.
Furthermore, these fillers may be thermally or electrically conductive. Conductive fillers may be used, for example, to create a conductive silicone layer, which in turn may be used as an electrode layer in sensors, actuators, or other EAP systems. Examples of thermally conductive fillers are aluminum nitride; alumina; barium titanate; beryllium oxide; boron nitride; diamond; graphite; magnesium oxide; particulate metals such as, for example, copper, gold, nickel or silver; silicon carbide; tungsten carbide; zinc oxide and/or combinations thereof. Thermally conductive fillers are known in the art and are commercially available. For example, CB-A20S and Al-43-Me are alumina fillers of different particle sizes, commercially available from Showa-Denko, and AA-04, AA-2, and AA 18 are alumina fillers, commercially available from Sumitomo Chemical Company. Silver fillers are commercially available from Attleboro, Massachusetts, Metalor Technologies u.s.a.corp. Boron nitride fillers are commercially available from Advanced Ceramics Corporation, Cleveland, Ohio, usa.
Reinforcing fillers include silica and chopped fibers such as, for example
The silicone composition may further comprise one or more optional components. Examples of optional components include, inter alia, (F) one or more solvents, and (G) one or more inhibitors.
The silicone composition may additionally optionally comprise (F) one or more solvents. However, it should be ensured that the solvent does not adversely affect the overall system. Suitable solvents are known in the art and are commercially available. The solvent may be, for example, an organic solvent having 3 to 20 carbon atoms. Examples of the solvent include aliphatic hydrocarbons such as, for example, nonane, decalin, and dodecane; aromatic hydrocarbons such as, for example, mesitylene, xylene, and toluene; esters such as, for example, ethyl acetate and butyrolactone; ethers such as, for example, n-butyl ether and polyethylene glycol monomethyl ether; ketones such as, for example, methyl isobutyl ketone and methyl amyl ketone; silicone fluids such as, for example, linear, branched, and cyclic polydimethylsiloxanes, and combinations of these solvents. The optimum concentration of a particular solvent in the adhesive formulation can be readily determined by routine experimentation. Depending on the weight of the compound, the amount of solvent may be 0 to 95% or 1 to 95% based on the total weight of the silicone composition.
Inhibitors (G) and stabilizers are used for targeted setting of the working time, the onset temperature and the crosslinking rate of the silicone compositions of the invention. These inhibitors and stabilizers are well known in the art of addition-crosslinking compositions. Examples of common inhibitors are alkynols, e.g. 1-ethynyl-1 Cyclohexanol, 2-methyl-3-butyn-2-ol and 3, 5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, polymethylvinylcyclosiloxanes such as 1, 3,5, 7-tetravinyltetramethyltetracyclosiloxane, compounds having methylvinyl group-SiO1/2Radical and/or R2Vinyl SiO1/2Terminal low molecular weight silicone oils such as divinyltetramethyldisiloxane, tetravinyldimethyldisiloxane, trialkylcyanurates, alkyl maleates such as diallyl maleate, dimethyl maleate and diethyl maleate, alkyl fumarates such as diallyl fumarate and diethyl fumarate, organic hydroperoxides such as cumene hydroperoxide, tert-butyl hydroperoxide and pinane hydroperoxide, organic peroxides, organic sulfoxides, organic amines, diamines and amides, phosphanes and phosphites, nitriles, triazoles, diaziridines and oximes. The activity of these inhibitor additions (E) depends on their chemical structure, and therefore the concentration must be determined individually. The inhibitor and inhibitor mixture are preferably added in a quantitative fraction of from 0.00001% to 5%, preferably from 0.00005% to 2%, and more preferably from 0.0001% to 1%, based on the total weight of the mixture.
After mixing all the components of the silicone composition, the shear rate was 1s-1A dynamic viscosity of from 10 to 1000, preferably from 100 to 100 and more preferably from 200 to 50, Pa.s, in accordance with DIN EN ISO3219:1994 and DIN 53019, using a calibrated rheometer with a cone/plate system, a cone CP50-2 opening angle of 2 DEG, at 25 ℃ and a shear rate of 1s-1Measured as follows. A suitable instrument is, for example, an MCR302 rheometer (size 105 μm) available from Anton Paar GmbH, Austria.
The crosslinkable silicone compositions of the invention have the advantage that they can be produced in a simple manner using readily available and therefore economical starting materials. Another advantage of the crosslinkable compositions of the invention is that, as one-component formulations, they exhibit high storage stability at 25 ℃ and ambient pressure and they crosslink rapidly only at elevated temperatures. The silicone compositions of the invention have the advantage that, in the case of two-component formulations, after mixing of the two components, they result in crosslinkable silicone materials which are processable at 25 ℃ and ambient pressure for a long time and therefore exhibit an extremely long pot life and crosslink rapidly only at high temperatures.
Examples of commercially available silicone compositions are (depending on the viscosity of the material, solvents can be added for better processability):
materials from WACKER Chemie Ag:
In addition to the crosslinkable silicone compositions described above, it is additionally possible for additional layers to be appliedA non-curing silicone composition such as, for example, silicone oil is used. In this context, the following products of WACKER Chemie AG, germany may be used:AK SILICONE OEL series,FLUID TR series,And (4) series. A silicone-based PSA (pressure sensitive adhesive) can be generally used.
Furthermore, another advantage in various applications is the use of non-curing printing compounds as carrier materials (support materials) or release layers (release layers). These materials can subsequently be removed or removed from the print without residues by rinsing and/or heating. A common printing compound here is polyethylene glycol (PEG). Suitable carrier materials are described, for example, in WO 2017/020971A 1 and WO 2018/036640A 1.
The individual layers of the silicone layer, the silicone membrane and the silicone multilayer composite described in the present disclosure preferably have a thickness of from 0.1 to 400 μm, more preferably from 1 to 200 μm, very preferably from 1 to 150 μm and especially preferably from 5 to 100 μm and are in the range of 200cm 2Each with a thickness accuracy of 5%, the preferred thickness accuracy in each case being 3%.
The determination of the absolute layer thickness can be carried out by means of SEM analysis (scanning electron microscopy analysis) and by means of cryosectioning. The surface quality and roughness are determined, for example, using a confocal microscope.
Preferably, at least the surface of the deposition support (36) facing the printing compound support (33) or the silicone material (35) is charged to an electrical potential phi _2, wherein phi _2 and phi _1 have opposite polarities, and phi _2 and phi _1 are chosen such that at least a part of the amount of charge of the silicone composition transferred onto the deposition support (36) in step (v) is neutralized on the surface of the deposition support (36).
Disposed between the printing compound carrier and the silicone composition is preferably an opaque separating layer which is heated upon irradiation with a laser beam. The opaque release layer may be permanently bonded to the printing compound carrier or may be configured as a release layer or a dissolving layer.
The focal point of the laser beam is preferably located above the printing compound carrier.
Preferably, the rheometer is calibrated by means of a cone-plate system, with a cone CP50-2 and an opening angle of 2 DEG, at 25 ℃ and a shear rate of 1s, in accordance with DIN EN ISO 3219:1994 and DIN 53019 -1The silicone composition has a dynamic viscosity of 10mPa · s or more and 1000Pa · s or less, more preferably 1 to 100Pa · s, measured as follows.
Preferably, the silicone composition is an addition-crosslinking silicone composition and comprises the following components:
(A) an organic compound or organosilicon compound containing at least two groups having aliphatic carbon-carbon multiple bonds,
(B) organosilicon compounds containing at least two Si-bonded hydrogen atoms, either in place of (A) and/or (B) or in addition to (A) and (B)
(C) An organosilicon compound containing SiC-bonded radicals having aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen atoms, and
(D) a hydrosilylation catalyst.
Preferably, the addition-crosslinked silicone composition comprises the following additional components:
(E) one or more fillers selected from the group consisting of: BET surface area of at least 50m2Fumed or precipitated silica/g, carbon black, activated carbon, graphite, graphene, diamond, carbon nanotubes, aluminum nitride, aluminum oxide, barium titanate, beryllium oxide, boron nitride, magnesium oxide, particulate metals, silicon carbide, tungsten carbide, zinc oxide, titanium dioxide, ferrites, NIR absorbers, MIR absorbers, and combinations of these fillers.
The silicone layer is preferably a dielectric silicone layer or a conductive silicone layer.
The silicone layer preferably has a layer thickness of 0.1 μm to 200 μm, as measured by scanning electron microscope analysis.
The printing compound carrier is preferably highly transparent to the laser beam and is selected from the group consisting of: glass, vitreous silica (vitreous silica), polyethylene terephthalate (PET), Polycarbonate (PC), polymethyl methacrylate (PMMA) and zinc selenide glass.
The deposition carrier is preferably selected from the group consisting of: PET, glass, ultra-thin flexible glass, and metal. In a cycle or from an upstream process step, a layer of cross-linked silicone, a layer of cross-linkable silicone composition, a silicone multilayer composite having at least two layers of cured silicone and/or a metal layer may be placed on the deposition support.
The existing layer on the deposition support is preferably a silicone film with a film thickness of 0.1 μm to 200 μm or a silicone multilayer composite with at least two layers of cured silicone, each layer having a layer thickness of 0.1 μm to 200 μm, measured in each case by scanning electron microscope analysis.
Preferably, the transferred silicone composition is laminated with a silicone film having a film thickness of from 0.1 μm to 200 μm or a silicone multilayer composite having at least two layers of cured silicone (each layer having a layer thickness of from 0.1 μm to 200 μm), in each case measured by scanning electron microscope analysis.
Preferably, the silicone membrane laminated on the deposition support or ready to be placed on the deposition support is obtained by separation from the membrane support, the separation comprising the following steps:
-immersing the membrane carrier with the silicone membrane thereon in a liquid bath and/or spraying the interior of the membrane carrier that has been separated from the silicone membrane with a liquid in the direction of the not-yet-separated silicone membrane by means of a spraying unit; and
-separating the silicone membrane from the membrane support.
The separated silicone membrane is preferably tested for damage by a regulated puncture tester. The ionization voltage used here is from 100 to 40000V, preferably from 2000 to 20000V.
Preferably, one or more further silicone layers are applied onto the transferred silicone composition by repeating steps (i) to (vi) of the above-described laser transfer printing method.
Preferably, the deposition carrier is configured as a moving conveyor belt, which is supplied from a deposition carrier roll (2) and collected in a storage roll (18a) after coating.
In an alternative embodiment, the deposition carrier is configured as a moving endless belt and is circulated via a belt store (18b) until the coating with one or more silicone layers and optionally the lamination with additional films is finished.
Preferably, the laser source is arranged to roughen, ablate, structure and/or cut the deposition support or the silicone layer applied thereon.
The method of the invention can be used to produce composite electrodes.
The silicone layer is preferably a conductive silicone layer, and the method preferably comprises the steps of:
-providing a dielectric layer, preferably a dielectric silicone layer,
-applying a conductive metal layer to the dielectric layer;
-applying a conductive silicone layer onto the conductive metal layer;
-applying a further conductive metal layer onto the conductive silicone layer;
-applying a further dielectric layer, preferably a dielectric silicone layer, onto the further conductive metal layer.
Preferably, the dielectric layers each have a layer thickness of 5 μm to 100 μm, the conductive metal layers each have a layer thickness of 0.01 μm to 5 μm, and the conductive silicone layers have a layer thickness of 5 μm to 100 μm, as measured by scanning electron microscope analysis.
Preferably, the printing compound carrier with the untransferred crosslinkable silicone composition resulting from step (v) is completely coated again with the crosslinkable silicone composition and used for applying one or more further silicone layers by laser transfer printing.
The full coating preferably comprises the following steps:
-separating the non-transferred silicone composition from the printing compound carrier by means of a carry-out (carry-off) system (this also includes separating the remaining non-crosslinked and/or crosslinked silicone composition from the areas of the previously transferred silicone composition);
-treating the separated silicone composition in a treatment system; and
-transporting the processed silicone composition to a printing compound carrier by means of a carry-on system.
The usual laser transfer printing process (LIFT ═ laser-induced forward transfer) is well described in the literature and is state of the art.
In the case of use with silicone compositions, it has proven advantageous to extend the method with a defined charge and additionally with an electrostatic field (EF LIFT — electric field laser induced forward transfer).
In the following, embodiments of the present invention are described by way of example with reference to fig. 1 to 6. However, they should not be understood as conclusive with respect to the constructive form of the present invention.
Fig. 3 depicts this EF LIFT process with fig. 30. In this case, a laser source (31) is used to separate the silicone composition (35) from a printing compound carrier (33) transparent to laser radiation by means of a laser beam (32). The separation occurs in a separation zone (38). Here, the laser beam (32) causes heating that causes the formation of a gas (e.g., by evaporating, subliming, or decomposing at least one component present in the silicone composition (35)). In further embodiments, the conversion of the laser radiation into heat may be performed by an additional opaque separating layer (34). This is particularly advantageous in the case of optically transparent silicone elastomers. In a typical LIFT process, the separation of the silicone composition (35) is sufficient to place the separated printing compound (39) on the deposition support (36). In the special case of LIFT processes using silicone elastomers, this separation and placement improvement can be achieved by additionally charging the printing compound and the carrier region. In that case, the silicone composition (35) is charged with an electric potential (phi _1), the surface of the deposition support (36) is charged with an electric potential (phi _2), and the electrode (37) is charged with an electric potential (phi _ 3). The polarity of these potentials should be selected to produce opposite charges. An electric charge with a distance (h) between the layers will generate an electric field (E). These in turn generate a force on the silicone composition (35) in the direction of the deposition support (36). Thus, the separated printing compound (39) is accelerated by electrostatic force and moves in the direction of the deposition support (36). During the separation and upon impact, the separated silicone composition (39) is subjected to a great mechanical shear force. An advantageous material composition (e.g. a shear-thinning silicone) is advantageous here for forming the water-impermeable layer (42).
The shear thinning behavior of silicone compositions is described, for example, in WO 2017/081028a1 in connection with ballistic printing processes.
In addition, electrostatic forces of the residual charge in the placed layer (42) act in the direction of the electrode (37). The charging of the deposition support (36) on the surface at a potential (phi _2) proves to be advantageous for relaxation, at a level lower than the charge of the silicone composition (39) placed. The residual charge of the material (42) should be selected such that the influence on the electric field (E) is as small as possible and the relaxation of the layer (42) can be improved or accelerated.
In many versions of the known LIFT method, focusing a laser beam onto an interface between a printing compound and a printing compound carrier (33) is mentioned. In versions using silicone, focusing over the printing compound carrier may result in better printed patterns. The focal point (40) here is in the range from a few micrometers to a few millimeters above the printing compound carrier (33). Focusing the laser beam on, in or under the interface first causes separation of the silicone composition (39), but this subsequently causes substantial secondary heating of the deposition support (36), resulting in combustion or thermal denaturation of the applied silicone composition (42).
A conventional laser source (31) is, for example, a Nd: YAG laser (neodymium-doped yttrium aluminum garnet laser) emitting laser radiation in the NIR range (near infrared, about 0.78 to 3 μm). For most laser systems, these wavelengths are used for coupling into opaque media (e.g., metals). In the applications described in the present invention, it is advantageous to use carrier materials such as glass, vitreous silica, polyethylene terephthalate (PET), Polycarbonate (PC), polymethyl methacrylate (PMMA), etc. for the printing compound carrier (33). In the case of transparent silicones, an opaque coating (34) or absorptive additive such as, for example, carbon black, graphite, graphene, Carbon Nanotubes (CNTs) must be present in the silicone composition. Non-conductive absorbers are commercially available from, for example, FEW Chemicals GmbH, Germany.
Other variations of the EF LIFT process may take the form of varying the wavelength of the laser (31) within the MIR range (mid-infrared, about 3 to 50 μm). In this case, the wavelength range of the conventional laser source is 10.6 μm (CO)2A laser). In this particular configuration, a clear silicone elastomer can be used in the EF LIFT process without the addition of an absorber and without an opaque separating layer (34). In this configuration, the printing compound carrier (33) is made optically transmissive for the relevant wavelength. For a wavelength of 10.6 μm, ZnSe glass (zinc selenide) is preferably used here. Particularly useful here are antireflective coatings at the interface of the ZnSe carrier. In this case, the usual supplier is LASER COMPONENTS GmbH, germany.
In the method of the invention, the wavelength of the laser is in the range of 0.78 μm to 20 μm, more preferably in the range of 0.9 μm to 12 μm, and very preferably in the range of 0.9 μm to 1.1 μm.
The separation layer (34) is known to the person skilled in the art and may consist, for example, of a layer deposited by CVD (chemical vapor deposition) or PVD (physical vapor deposition) or of another opaque substance. The layer may preferably be attached to the printing compound carrier (33) such that the separation layer (34) does not separate from the printing compound carrier (33) when heated by the laser (31).
In fig. 4, in process diagram (49), an application system for the printing compound (35) is depicted. In this case, the non-transferred printing compound (35) is separated from the printing compound carrier (33) and/or from the separating layer (34) by a carry-out and carry-in system (43), which is coated again over its entire area with the printing compound. A loading unit (44) draws the non-transferred printing compound (35) and a part of the non-separated printing compound from the printing compound carriers (33,34) into the region (41). The printing compound carrier here moves in the positive X direction towards the separation unit. The PTFE stripper and the removal edge made of soft material are proved as a carrying-out unit (44) ) Is advantageous. The separated old printing compounds are transported out of the loading-out unit (44) by the processing unit (45), mixed and subjected to a defined mechanical shearing. The shear rate to be generated should preferably be selected in the range from 0.1 to 1000s-1More particularly in the range of 0.1 to 100s-1Within the range of (1). Too high a shear rate may adversely affect the properties of the filler incorporated into and printing the compound. Too low a shear rate leads to poor mixing and/or to poor coating of new layers. The printing material is supplied and replenished by feeding printing compound from a storage container (47) into an overprint zone (46) of the loading system. The feed may take the form of a dotted line from the vessel (47) to the zone (46), or a loop with a permanent flow of material in between. Preferably, shear forces are permanently applied to the printing compound in the container (47) and the zone (46) by circulating the printing compound between the two zones. In particular, the container (47) or the entire application system is heated in addition to the shearing. In this case, the loaded printing compound is reheated by material circulation between (47) and (46). The temperature of the material present is in the range-10 ℃ to 150 ℃, more preferably in the
The supply of material to the storage container (47) is carried out by means of a conventional metering system with venting. Such a system is available, for example, from Visco Techpumpen-u.Dosiertechnik GmbH, Germany.
Due to the pressure increase and shear in the region (46), a bubble-free, uniform silicone layer having a thickness of 1 to 400 μm, preferably 10 to 50 μm, more particularly 10 to 20 μm, is applied to the printing compound carrier. Using a precision thickness remover (48), the renewed layer (35) of printing compound is again narrowed to a layer thickness deviation of +/-5% and may optionally be charged to an electrical potential (phi — 1). In this case, the precision thickness remover is conductive. At least one overlapping precision blade (lapped precision blade) made of hardened metal is preferably used here. Particularly preferred here are scrapers/materials which do not show material ablation, are resistant to corrosion and solvents and are approved in medical applications.
In another form, charging the printing compound to the potential (phi _1) may be accomplished contactlessly by ionization (22). This may be done alone or in combination with charging at the thickness remover (48). Conventional regulated ionization systems are known to the skilled person and are available, for example, from Simco-Ion, the netherlands.
Fig. 1 illustrates a roll-to-roll process for producing a multilayer silicone elastomer system, in accordance with various embodiments.
In process diagram (1), rolls (2) and (3) consisting of a non-stretchable conveyor belt (36) deliver an ultra-thin electroactive film (55) of elastomer or elastomer laminate (14) to process (1), optionally on said belt (36), and optionally with a laminating film (4). The laminated film (4) is removed during the development process.
According to principle (30), coating systems (5) and (6) bring the printing compound (electrode material and/or non-conductive material) in non-crosslinked form onto a deposition support (36) or laminate (14). The geometry of the layer to be applied can be varied as desired. An active camera system (16) may be used to ensure geometrically defined positions of the layers. In that case, the camera system (16) checks the shape and position of the layers that have been applied in the laminate (14). The advanced control and regulation unit controls and positions the coating systems (5) and (6) as a function of information from the camera system (16) and other regulating variables such as, for example, the web speed (web speed) or set potentials such as, for example, phi _1, phi _2 and phi _ 3.
The applied layer is then laminated together with an elastomeric membrane (55), which elastomeric membrane (55) is separated from the membrane carrier (19) in a delamination unit (7).
Fig. 5, in a detailed view (50), shows a mild defect-free separation mechanism for ultra-thin elastomeric films (preferably 1 to 200 μm). An ultra-thin film (55) of elastomer is continuously separated from a non-stretchable film conveyor belt (19), preferably immersed in a liquid bath (51) or produced under the influence of liquid wetting (52), in particular by a spraying device (54). The free film conveyor belt (19) is then collected on a winding unit (9).
The principle of gentle separation of the elastomer membrane is based on the reduction of chemical and physical adhesion, due to the presence of a liquid hydrophilic intermediate layer (57) in the separation region of the hydrophobic membrane of the elastomer and the membrane support. Upon separation, the liquid interface in the bath forms a contact line on the membrane carrier that exerts a capillary-induced removal force on the edge of the elastomeric membrane (55). The apparatus may optionally include a position adjustable guide roller (56) that defines a separation angle between the elastomeric membrane and the membrane carrier.
In the case of a pretreatment of the membrane support (19) with, for example, a release agent component which is soluble in the liquid (51) in the bath (8), the required separating force can be deliberately reduced here between the fully crosslinked membrane of the elastomer and the membrane support by dissolving the layer in a liquid tank. Another advantage of the separating means according to the invention is that in the presence of a layer of liquid, the electrostatic charge is neutralized and the adhering dirt particles are also continuously removed. Subsequently, the droplets adhering to the elastomeric film (55) are removed from the elastomeric film (55) by an air ejection unit (10), such as an air roller, an air ejector, or a fan.
The rotation speed of the rollers (53) can optionally be different to thereby achieve a determined preliminary stretching of the free film (55) of elastomer.
In the case of liquid-assisted separation of elastomeric films, particularly with ultra-pure water, support may be provided by the addition of surface-active additives (e.g., surfactants). The general surface modification of the membrane support (19) can minimize the adhesion forces there, thereby improving the separation process. The general manner and method are known in the art.
By means of the discharge device (20), after unwinding from the deposition carrier roll (2), the deposition carrier (36) is discharged together with all silicone material, silicone layer and/or laminate (14) located thereon.
The contactless charging (21) charges the deposition carrier surface (the surface of the deposition carrier (36) to be printed) to an electric potential (phi _ 2). Here, the deposition support surface is the topmost area that is printed with the printing systems (5) and (6).
In the printing system, the printing compound is charged to a potential (phi _ 1). The field electrode (37) of potential (phi _3) is located below the printing systems (5) and (6), following the deposition support (36).
By means of the discharge device (20), the deposition carrier (36) is discharged together with all silicone material, silicone layers and/or laminates (14) located thereon. The charging unit (23) charges the uppermost layer and/or the applied printing compound (42) on the deposition support (36) to the potential (A) in a defined manner.
The free elastomer film (55) is locally charged to an electrical potential (B) on the side facing the applied printing compound (42) by means of a charging device (25). When the silicone film (55) is deposited on the printing compound (42), the potentials (a) and (B) are of different polarity and have an attracting and adhering effect.
The operation of electrostatic lamination is known in the art and is used in a variety of lamination processes.
The roller (11) sets the deposition angle and any mechanical pressure that may be necessary to deposit and to the laminate (14). The laminate (14) thus produced is guided through a field unit (26), wherein a magnetic and/or electric field influences the uncured silicone layer. This may have the effect of producing any change in the elastomer layer, from induction heating to alignment of the magnetic filler. The laminate is crosslinked in a curing station (12). In the cooling station (13), the laminate is cooled. The laminate film (4) is then inserted on a roller (18a), and the cured and cooled laminate is then collected (rolled up).
For error detection, the puncture tester (24) performs a contactless test on the free-floating elastomeric film (55) to check for damage and weakness. After the test, a discharge is performed by a discharge device (20). The weakness or defect can be identified by electrical breakdown and signaled by a puncture tester (24). The arc present at the defect can cause burning and produce a discernible coloration or change at the breakdown site. The identified and signaled defects are evaluated in an advanced control and regulation unit and assigned and optionally marked according to web position (web position). The area below and around the defect will be recorded in the software of the control and regulating unit and then declared as defective.
The position of the defect is recorded in a separate form and, in a subsequent new printing and/or lamination process, the surface of the defect is removed by means of a laser and refilled with insulating silicone elastomer by means of a printing unit (6).
Key issues such as separation and separation angle, pre-tension, stretch, deposition angle, and air inclusions have a significant impact on the accuracy and functionality of subsequent EAP systems. For example, the deposition of the film is not ideal and air may also be entrapped during the application of the additional layer, resulting in subsequent blistering during the curing operation.
Simple mechanical separation results in partial or complete damage to the silicone membrane. This leads to electrical breakdown and component failure on subsequent use in EAP systems.
As a result of any dry separation of the film from the film support, spikes are formed and the film is partially over-stretched and cracks or pores are created. These local overexposures occur in the case where all the cleaning processes are carried out in air. Adhesion is only achieved with the use of water film separation, and therefore the mechanical load of the silicone film is reduced to such an extent that damage can be avoided. Removal under water or simple wetting of the removal edge results in a significant reduction in adhesion and in a reduction in the mechanical load on the membrane.
Figure 2 shows a particular embodiment of the process with process diagram (29). In this case, instead of coating/laminating the cured silicone layer, it is instead applied in a wet process by means of a coating system. The method is characterized in that the deposition carrier (36) is realized in the form of an endless belt which is not stretchable. The endless belt may already carry multiple layers of silicone elastomer. The electrically neutral layer on the circulating belt is removed from the circuit memory (18b) and charged to a potential (C) by a charging unit (27). An applicator (15) deposits a layer of silicone on the deposition support and on the entire area of the layer lying thereon. A charging unit (28) charges the silicone material of the applicator (15) to an electrical potential (D). The potentials (C) and (D) are different in polarity, and thus an electrostatic force is generated. In this case, the coating process is supported by the action of electrostatic forces. After deposition or coating of the layer by the applicator (15), the curing station (12) partially effects curing of the partially to fully coated layer. The deposition support is electrically neutralized together with all layers lying thereon by means of a discharge station (20).
The printing operation (5,6) is carried out again, as described above, up to the curing station (12). Thereafter, a silicone layer may optionally be further applied, as described above. The entire solidification and influencing by the field then takes place in the field unit (26), in the solidification station (12) and also in the cooling station (13).
A web guide (17) adjusts the endless belt and the deposition carrier (36) according to the web position and the web tension, respectively. A loop memory (18b) intermediately stores the necessary number of processes or batch size according to the desired batch size. When the desired number of layers is reached, the silicone elastomer laminate is removed from the endless belt. Conventional extraction devices are known in the art.
In a particular configuration of the method, the surface to be coated is roughened and/or ablated or structured, respectively, before the EF LIFT method. In addition, the laser system may be configured for singulation on the deposition conveyor belt (36). During this process, the deposition conveyor (36) is not damaged.
For example, the silicone layer can be cut and directionally ablated using an engraving laser with a wavelength of 10.6 μm. Further, for example, with a 9.3 μm laser, improvement in cutting accuracy can be achieved. Therefore, different laser sources (e.g., wavelength: 1.06 μm and 10.6 μm) are installed to be suitable for the system for cutting and the system for LIFT printing.
In a particular variant of the method, the electrode is constructed as a multilayer system (composite electrode). Fig. 6 shows such an electrode arrangement in cross-section (60). A thin silicone layer (62) containing a very well conductive substance (e.g., metal, CNT, conductive carbon black, etc.) is combined with a very soft conductive layer (63) to form an electrode. In the electrode, the layer (63) has a function of transferring electric charges to the electrode charging surface (62). The highly conductive layer (62) generally lacks long-term elasticity and becomes fragile during plastic stress of the EAP system and tends to impair charge transport up to the overall insulation of the individual regions. The function of separating the charging surface and charge transport solves this problem.
In terms of process, the application of the metal layer can be carried out by LIFT and EF LIFT methods, as well as other different methods.
The application in the above-described method can be carried out by means of a printing belt with a metallic printing compound and/or a printing layer. The adhesive component is superfluous when applied directly to the uncured silicone elastomer material.
For example, the electrode surface may be formed of an elastomer with carbon black filler. In this case it must be borne in mind that in order to obtain sufficient conductivity, the filler fraction must generally be higher than 50% by weight, based on the total electrode mass. Under mechanical load (tensile elongation), a deterioration in electrical conductivity may be observed.
All EAP systems have a physical background of mutually attractive and/or repulsive charges. The structure always takes the form of a layer, and therefore the charge should be ordered in the charging area or region. These regions determine the effective distance between the electrodes, which is a factor in effectiveness. A silicone layer filled with a conductive material, preferably CNTs, can be used to transport charge to the electrode surface. The electrode surface is made of a very thin metal layer, preferably of aluminium.
If the actuator is not present with an elastic conductive layer, the heating of the mechanical load area increases and there are also hot spots on the degraded electrode surface. This can be attributed to poor adhesion of the layer, the formation of cracks and lack of elasticity. Incorporation into the resilient conductive layer solves this problem.
The method of the invention is preferably used for manufacturing sensors, actuators or other EAP systems comprising at least two electrodes and at least one dielectric silicone layer arranged between the electrodes.
In this case, the silicone layer may be an electrode layer and/or may be a dielectric layer in a sensor, actuator or other EAP system.
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