EP3994226A1

EP3994226A1 - Surface-modified silicone, use thereof in nonstick coatings and composite material containing same

Info

Publication number: EP3994226A1
Application number: EP20737397.8A
Authority: EP
Inventors: Ralph Wilken; Laura SCHILINSKY; Christopher DÖLLE; Christoph SCHMÜSER; Martin WIESING
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2019-07-04
Filing date: 2020-07-01
Publication date: 2022-05-11
Also published as: DE102019118173A1; WO2021001448A1

Abstract

The invention relates to a surface-modified silicone, wherein a particularly small amount of carbon has been exchanged in said surface-modified silicone compared with an unmodified silicone, to a composite material comprising said silicone and a carrier material, as well as to a method for producing said surface-modified silicone. Furthermore, the use of said surface-modified silicone in nonstick coatings and the use of said composite material as a separating film and/or as a release liner for substances having high surface adhesion power are described.

Description

Surface-modified silicone, its use in non-stick coatings and composite material containing it

The present invention relates to a silicone with a modified surface, with this silicone with a modified surface particularly little carbon being exchanged for the unmodified silicone, a composite material comprising said silicone and a carrier material, as well as a method for producing said silicone with a modified surface . The present invention also relates to the use of the said silicone with a modified surface in non-stick coatings and the use of the said composite material as a release film and / or as a release liner for substances with high surface adhesion.

Siliconization on foils and papers is used in a variety of ways, especially as release foils or release papers, for example to protect pressure sensitive adhesives and other substances with a high surface tack ("surface tack") such as highly viscous media, adhesives, varnishes or similar from unwanted sticking. Typical examples of such products are self-adhesive labels and self-adhesive semi-finished products such as mirror mountings, pressure-sensitive adhesives from or on screens of, for example, tablet computers or smartphones, and attachments in the vehicle exterior, such as trim strips or logos, or in the vehicle interior. Such release films or release papers (often also referred to as “release liners”) are peeled off the pressure-sensitive adhesive and the adhesion is carried out by bringing it into contact with the substrate before the desired gluing.

In many cases, the release force, that is to say the force that has to be applied to peel the release liner from the pressure-sensitive adhesive, must be set in a targeted manner. An example is the double-sided adhesive tape, in which one side of the release liner has to have higher release forces in order to ensure that the release line is always on one side, namely on the side of the pressure-sensitive adhesive that is to the center of the adhesive tape roll shows. This ensures that with a double-sided adhesive tape, the roll is always covered on the outside with the release liner and the pressure-sensitive adhesive is not exposed.

This targeted setting of different release forces in siliconized release films or release papers is currently achieved using conventional technology, mostly by varying their dynamic mechanical properties by adding crosslinkers ("controlled release additives") such as known "MQ resins" to the Formula of the silicone elastomer can be added. Layer thicknesses of the silicone and the substrate can also influence the later release properties.

The disadvantage of this conventional technology is that a change in the separating force usually requires a change in the silicone recipe, and this leads to considerable additional expense in the production of web goods. Smaller batches of special papers in particular cannot be produced cost-effectively in this way. A laterally resolved setting of the separation force on a release liner (ie the adjustment of different separation forces at different points on the surface of a release film or a release paper, e.g. for easier removal in an area of a label with a "handle") is not possible with this conventional technology. Furthermore, when using release papers based on classic silicone elastomer coatings, there is often an undesired transfer (“set-off”) of uncrosslinked components of this silicone elastomer to objects in contact with them, e.g. to the pressure-sensitive adhesive of an adhesive tape made with such a classic release paper . In the prior art, various techniques for modifying surfaces have been discussed, including in the following documents: The document WO 2015/044247 relates to a plasma-polymer solid, in particular a plasma-polymer layer.

The document WO 01/32949 A1 specifies a method and a device for plasma coating of surfaces. The document WO 2008/132230 A2 describes a method for producing thin layers and a corresponding layer.

The document WO 2015/075040 A1 describes a method for connecting silicone rubber to a substrate.

The document WO 2016/030183 A1 (equivalent to DE 10 2014 217 000 A1) describes surface-modified silicone and a method for its production. It has been shown, however, that in the case of irradiation in the dose range specified in this document, the release effect of silicone surface-modified in this way with respect to pressure-sensitive adhesives is largely or completely lost, so that siliconizations treated in this way largely or completely lose their release effect. Document EP 0 165 059 A2 relates to a material with low surface energy.

The document EP 0 550 510 B1 (equivalent to DE 692 24 370 T2) describes a composition of a modified polysiloxane and a rubber article coated therewith.

V.M. Graubner et al. in Macromolecules 37 (2004) 5936-5943 deal with the photochemical modification of crosslinked poly (dimethylsiloxane) by irradiation at 172 nm.

The document WO 2019/197492 A1 describes a surface-modified silicone, its use in non-stick coatings and a composite material containing this. In view of the known prior art, it was a primary object of the present invention to produce a silicone with a modified surface or a composite material containing this, which has specifically adjustable and, in particular, laterally resolved release properties with respect to pressure-sensitive adhesives and, if possible, at the same time enables a low set-off. It was the aim of the present invention to be able to reliably produce relatively small increases in adhesive force and preferably to modify the original silicone little with regard to at least part of its composition. In the context of the present invention, “set-off” is understood to mean the transfer of Si-containing components from one surface to another during or after the surfaces come into contact with one another. In the context of the present invention, a "small set-off" preferably denotes the transfer or removal from a modified silicone surface according to the invention with an Si content of <1.5 at% after contact with another surface, in particular the surface of a pressure-sensitive adhesive tape, each measured with X-ray photoelectron spectroscopy (ESCA).

A further object of the present invention was to produce a method for producing said silicone with a modified surface or a composite material containing this. Another specific object of the present invention was to provide a said silicone with a modified surface for use in non-stick coatings and to provide a said composite material containing said silicone with a modified surface for use as a release film or release liner liner for fabrics with high surface adhesion. It has now surprisingly been found that the primary object and further objects and / or sub-objects of the present invention are achieved by a silicone with a modified surface, preferably with a surface modified by UV radiation, the concentration of silanol groups on the modified surface versus the concentration of silanol groups in the unmodified silicone is increased by 0.0015 at% to 0.13 at%, preferably by 0.0015 at% to 0.08 at%, measured by ESCA after chemical gas phase derivatization and based on the total number of atoms detected by ESCA (X-ray photoelectron spectroscopy).

The specification “atomic percent” (at-%) is a percentage of the content of an atomic type (eg for silicon) in a mixture containing this atomic type, customary in the technical field. It is defined as the quotient of (i) the number (or amount of substance) all in one Mixture (usually in a solid) containing atoms of the type of atom under consideration (e.g. silicon) and (ii) the number (or amount of substance) of all atoms contained in the mixture (if these are accessible to the measuring method or measuring technology used):

Number of atoms (type of atom)

at—% (atomic type) = - —— - * 100

Total number of all atoms All content data in “at-%” in the present text therefore take into account, if X-ray photoelectron spectroscopy (ESCA) was used as the measuring method for determining the content, in particular not atoms of the types hydrogen and helium due to the method used. Appropriate method-related features of X-ray photoelectron spectroscopy are known to the person skilled in the art. The concentration of silanol groups is determined as in measurement example 1 and, if necessary, taking measurement example 2 into account. For the purposes of this text, the determination for silanol groups applies, even if it is not chemically excluded that the detection method from measurement example 1 also detects other reactive groups. This is also technically understandable, because for an increase in the separation force - without being bound by theory - generally reactive groups which can be detected in the derivatization experiments described have an effect. Therefore, other reactive centers or groups within the meaning of the invention with silanol groups are to be assessed equally and are subsumed under silanol groups if they are included in the derivatization. In case of doubt, the procedure according to measurement example 2 is used to determine the depth at which a constant fluorine concentration is present after derivatization and thus the unmodified starting material. After three times the mean depth range t1 (i.e. after 3 * t1), the fluorine concentration is considered constant and the material as unmodified in case of doubt. For the purposes of the present application, the layer thickness range up to this depth (3 * t1) is considered modified. The mean depth range 1 correlates with the mean penetration depth of the radiation. The modification depth (3 * t1) therefore corresponds by definition in the present application to the penetration depth of the radiation.

In the case of very thin layers, it is possible that an unmodified starting material is no longer available. In this case, however, it is possible to use the formula described in measurement example 2 to determine what the silanol content of the unmodified material looked like. The detection limit for silanol groups can be further increased by a suitable choice of the ESCA measurement parameters and the derivatization reagent CI- (CH3) 2Si- (CH2) 2 (CF2) xCF3 with x = 0-10. Corresponding to the number of fluorine atoms in the derivatization reagent FZ = 2 * x + 3, based on 250 ppm (0.025 at%) detection sensitivity for fluorine in the ESCA experiment, there is a lower detection limit for silanol groups of 250 ppm / FZ, so that a detection of very low concentrations up to down to a few ppm of silanol groups can be achieved. For x = 0, the lower detection limit accessible in the ESCA experiment (as described in measurement example 1) is about 80 ppm reactive centers (silanol groups), for x = 5 20 ppm silanol groups. The person skilled in the art is thus able to determine even very slight changes in the silanol concentrations by using the appropriate reagent.

The inventors have surprisingly found that, particularly in the area of very low increases in adhesive force, the control of the silanol groups in the sense of the present text is an extremely suitable variable in order to achieve the desired effects. This could not be foreseen from the state of the art known to date, and there were also hardly any detection methods with which the corresponding results of the respective modification could be checked.

The invention and combinations of preferred parameters, properties and / or components of the present invention preferred according to the invention are defined in the appended claims. Preferred aspects of the present invention are also given or defined in the following description and in the examples.

Preference is therefore also given to a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface which is specified as preferred in this text), preferably with a surface modified by UV radiation, with a surface of the modified surface or the surface modification having an opposite unmodified silicone has a carbon content reduced by <0.1 atom%, measured by ESCA and based on the total number of atoms detected by ESCA.

This small exchange of carbon, usually within the measurement error of ESCA, indicates that the original silicone was structurally very little changed. Ultimately, the exchange of atoms from the original composition always carries the risk of undesired side reactions taking place. Even before this Background it is desirable to keep the proportion of exchanged carbon as low as possible compared to the unmodified silicone.

For the purposes of this invention, a “modified surface” of a silicone comprises a structural change and / or a change in the material composition of the modified surface compared to the unmodified silicone, the modification preferably by means of radiation, preferably by means of UV radiation (for the preferred wavelength range see below), particularly preferably by means of VUV radiation, and very particularly preferably by means of longer-wave VUV radiation (> 150 nm - <190 nm). It has been shown that the modification of the silicone surface according to the invention leads, at least in the preferred cases, to a slight increase in the oxygen content and only to a slight reduction in the carbon content compared to the unmodified silicone. It is assumed in this context that the reduced carbon content is caused by the degradation of carbon functions (here caused by radiation), accompanied by the incorporation of oxygen functions, in particular the formation of silanol groups.

In the silicone according to the invention with a modified surface, only one surface can be modified (preferred) or two or optionally (if present) several surfaces can be modified.

As unmodified silicone for the purpose of comparison with the silicone according to the invention with a modified surface, (i) an unmodified silicone from the same batch of manufacture, (ii) an unmodified part or area of the surface of the silicone according to the invention with a modified surface can be used or (iii) the unmodified silicone below the modified surface of the silicone with modified surface, preferably at a depth of> 1 pm, particularly preferably at a depth of> 3 pm, below the modified surface. This is related to the usual penetration depth of the longer-wave VUV radiation, which is particularly preferably used to modify the surface of the silicone, with wavelengths in the range from> 150 nm to <190 nm, which as a rule is the depth given above of 1 pm or 3 pm does not exceed. Below this penetration depth, the effects according to the invention of the surface modification of the silicone in a silicone with a modified surface can practically no longer be detected, but can be calculated in the manner described above. Preferably and in case of doubt, in the context of the present invention for comparison of the silicone according to the invention with a modified surface, in particular of its modified surface, or its (their) properties, the unmodified silicone below the modified surface (above alternative (iii)) is used.

In the context of the present invention, “silicone” is understood to mean a poly (organo) siloxane in which silicon atoms are linked via oxygen atoms. A silicone in the context of this invention can be present in uncrosslinked form (rubber), partially crosslinked or completely crosslinked. Partially crosslinked means that, preferably within the scope of a vulcanization reaction, further crosslinking up to complete crosslinking (fully crosslinked) can take place. The molecular chains are preferably at least partially crosslinked. The remaining free valence electrons of the silicon are saturated by hydrocarbon radicals, hydrogen or by functional groups that are or contain heteroatoms. A silicone within the meaning of this text can include conventional additives such as additives or fillers and has a

Hardness of preferably SHORE> 1, more preferably> SHORE 3, classified according to the SHORE A test. The SHORE A hardness is measured according to DIN ISO 7619-1: 2010.

According to the invention, silicones are preferably selected from the group consisting of silicone elastomer, silicone resin and silicone rubber, silicone elastomers being particularly preferred and silicone oils not being included.

Silicone elastomers have a SHORE A hardness of 1 to 90, preferably 3 to 80, and / or a modulus of elasticity at 100% elongation <5 MPa and / or a tensile strength of <11 MPa. The SHORE A hardness is preferably measured according to DIN ISO 7619-1: 2010. The tensile strength and the stress values in the tensile test (modulus of elasticity at 100% elongation) are preferably measured in accordance with DIN 53504: 2009-10.

A silicone resin is not an elastomer, which preferably means that the elongation at break of the material of a silicone resin is <100% according to the definition given above. Silicone resins typically do not contain fumed silica as a filler. In fully cross-linked form, “silicone resins” in the sense of this text preferably have a SHORE D “hardness” of 20-50 measured according to DIN ISO 7619-1: 2010.

Silicone rubbers are (as opposed to silicone oils) silicones that can be converted into a rubber-elastic state and have groups that are accessible for a crosslinking reaction, such as hydrogen atoms, hydroxyl groups, vinyl groups or acetate residues. In a special version (UV-crosslinking silicone rubber), uncrosslinked silicones can carry organic residues with an acrylate or epoxy function as functional groups. Silicone rubbers have a viscosity of 50 mPa * s to 700,000 mPa * s, preferably 1000 mPa * s up to 500,000 mPa * s, particularly preferably 5,000 mPa * s to 200,000 mPa * s. The viscosity is preferably measured according to EN ISO 3219.

It is particularly preferred in the context of the present invention that the unmodified silicone is a silicone elastomer that resulted from an addition reaction, preferably a UV radiation-induced addition reaction, or more preferably a transition metal-catalyzed addition reaction, and very particularly preferably a Pt-catalyzed addition reaction is.

Also preferred is a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface which is specified above or below as preferred), the modified surface being a surface modified by UV radiation, preferably by VUV radiation.

In the context of the present invention, “UV radiation” refers to electromagnetic radiation with a wavelength in the range from> 50 nm to <380 nm.

As “VUV radiation” (vacuum ultraviolet radiation) in the context of the present invention - as is customary in the field (cf. for example the standard DIN 5031-7: 1984-01) - electromagnetic radiation with a wavelength in the range from 100 to 200 nm. In the context of the present invention, “longer-wave VUV radiation” denotes VUV radiation with a wavelength in the range from 150 to 190 nm. VUV radiation and longer-wave VUV radiation are accordingly preferred subregions of the UV radiation to be used according to the invention in the context of the present invention.

Preference is also given to a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface that is specified above or below as preferred), the modified surface having a higher separation force compared with the unmodified silicone compared to the adhesive surface of a reference adhesive tape, the reference tape preferably being TESA 07475 and where the separation force increase is in the range> 10% to <579%, preferably> 20% to <299%, particularly preferably> 28% to <299%, based on the separation force of the unmodified silicone. In comparison with the unmodified silicone, the said modified surface preferably has a higher release force with respect to several or all of the reference adhesive tapes selected from the group consisting of Tesa®-Film 57386, Tesa®-Film 57370, Tesa®-Film 57405, Tesa ®-4651, Tesa © -07475, Tesa © -07475 PV2 and Tesa®- 07476 and Tesa®-4154. The designations given above for the reference adhesive tapes preferably refer to those compositions of the reference adhesive tapes as they are or were commercially available on the filing date of the present invention.

As reference adhesive tape to be preferably used above according to the invention, which is a single-sided adhesive tape and comprises a carrier material comprising polyethylene terephthalate and wherein the pressure-sensitive adhesive coating comprises a polyacrylate pressure-sensitive adhesive, a corresponding adhesive tape is preferably used which has an adhesive strength on steel in the range from 5 to 15 N / cm, preferably Range from 10 to 15 N / cm, preferably measured according to the method specified in document WO 2016/071387 A1, page 13, lines 12 to 22. Particularly preferred as the corresponding reference adhesive tape to be used with preference according to the invention are the reference adhesive tape “Tesa®-07475” in the composition or with the properties as they existed or existed on the filing date of the present invention. This reference tape is recommended by the FINAT organization (“Federation Internationale des Fabricants et Transformateurs d'Adhesifs et Thermocollants sur Papiers et Autres Supports”) for performing peel tests. FINAT is the European association of manufacturers of self-adhesive products.

For the purposes of the present invention, the 180 ° peel test based on test method FINAT FTM 10 is preferably used as the peel test for the purposes of the present invention, as described in the FINAT Technical Handbook, 9th edition 2014, with a FINAT test roller (pressure roller) 5kg roll is used, preferably as described in measurement example 3 of the present text.

The peel test to determine the release force of the modified surface of a silicone according to the invention with a modified surface is preferably carried out with a composite material according to the invention (see below), which comprises a silicone according to the invention with a modified surface and preferably on one of the surfaces of its carrier material with a carrier material according to the invention Silicone is coated with a modified surface, the modified surface of the silicone facing away from the carrier material and is thus available for the peel test. Furthermore, a silicone according to the invention with a modified surface is preferred (or a silicone according to the invention with a modified surface specified above or below as preferred), the separation force measured with a peel test against the adhesive surface of a reference adhesive tape, the reference tape preferably being TESA 07475, in the range of 0.018 N / cm to 1.2 N / cm, preferably from 0.02 N / cm to 0.75 N / cm, particularly preferably 0.031 N / cm to 0.38 N / cm.

According to the invention, the modified surface and / or the unmodified silicone (from which the silicone with a modified surface is or has preferably been produced) preferably comprises at least partially crosslinked silicone elastomer. The at least partially crosslinked silicone elastomer preferably comprises units of dimethylsiloxane, phenylmethylsiloxane, copolymers of dimethylsiloxane, copolymers of phenylmethylsiloxane and mixtures thereof. Preference is also given to a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface which is specified above or below as preferred), the unmodified silicone being based on a dimethylsiloxane, a phenylmethylsiloxane and / or diphenylsiloxane and their copolymers.

According to the invention, uncrosslinked silicone can also be used as the unmodified silicone whose surface is modified.

Surprisingly, it has been shown that uncrosslinked, UV-crosslinking silicone rubbers, which usually crosslink by UV light with wavelengths> 220 nm, also crosslink by irradiation with VUV radiation with wavelengths in the range from> 150 nm to <190 nm and then in one practically not to be separated step can also be modified by the irradiation.

This enables the VUV irradiation of uncrosslinked silicone rubbers to crosslink the silicone rubber to the silicone elastomer in the same process step as the VUV irradiation-induced adjustment of the release properties of the silicone elastomer. According to the invention, silicone which comprises MQ resin, preferably with a mass fraction of MQ resin in the range from> 3% by weight to <50% by weight, particularly preferably in, can also be used as the unmodified silicone whose surface is modified Range from> 20% by weight to 35% by weight, based on the total mass of the unmodified silicone comprising MQ resin. However, unmodified silicone comprising MQ resins is not preferred for the purposes of the present invention, since it is often not possible to achieve satisfactory selectivity in the range of low release forces.

The level of the respective release force of a pressure-sensitive adhesive of a conventional silicone-based release liner is usually set by means of silicone resins and in particular by means of so-called MQ resins. A good overview of silicone resins and especially MQ resins is provided by D. Satas, Handbook of Pressure Sensitive Adhesive Technology, 3rd Edition, p. 664.

The different separation forces of the individual release layers compared to a pressure sensitive adhesive are then the result of different MQ resin proportions in the respective release composition. Although the MQ resins offer the option of setting the release forces, e.g. of a release liner, and in particular the release forces of the release liner on the sides of a double-sided adhesive tape (and separately from one another), a specific silicone composition must be selected for each desired release force which is then coated on a carrier and cured. This makes it necessary to use several release liners with different MQ resin contents and to stock them if there is a need for different release properties. Because of the great variety of different pressure-sensitive adhesive compositions, such a storage is hardly feasible. Furthermore, the use of many different pressure-sensitive adhesive compositions can lead to increased waste material, since the individual pressure-sensitive adhesive compositions cannot be stored permanently. Instead, for example, the respective pressure-sensitive adhesive composition must be produced directly before application.

A silicone according to the invention with a modified surface is therefore preferred (or a silicone according to the invention with a modified surface which is specified above or below as preferred), wherein the modified surface and / or the unmodified silicone (from which the silicone with modified surface is or was preferably produced) comprises at least partially crosslinked silicone elastomer, the at least partially crosslinked silicone elastomer preferably comprising dimethylsiloxane units, and / or in the unmodified silicone (from which the silicone with modified surface is or was preferably produced) the proportion of oxygen, based on the total number of atoms present in the silicone with the exception of hydrogen atoms, <33 at%, preferably <30 at% and particularly preferably < 27 at%, preferably measured by means of elemental analysis.

The silicone according to the invention with a modified surface thus preferably comprises silicone which only comprises a small proportion of MQ resin or resins, particularly preferably which does not contain any MQ resin or resins. With the silicone according to the invention with a modified surface, it is particularly well possible to selectively set different separation forces even in the range of relatively low separation forces.

A silicone according to the invention is particularly preferred, the unmodified silicone containing no controlled release additives, in particular no MQ resins and no pyrogenic silicas.

The advantage of this particularly preferred silicone according to the invention is that the increase in the separating force can be attributed exclusively to the modification of the silicone. In principle, however, it is of course possible to use an interaction between controlled release additives (CRA) and the modification of the silicone to be used according to the invention:

Surprisingly, it has been shown that polyacrylate-based adhesive tapes and polyisoprene-based adhesive tapes react differently to CRA-additive and VUV-modified siliconizations.

While polyacrylate-based adhesive tapes (generally and when using polyisoprene adhesive tape Tesa 7476 or 4154 compared to acrylate-based Kelbebeand Tesa 7475) react weaker to CRA additives than polyisoprene-based adhesive tapes, the reverse is true for VUV modification. This enables silicone release liners to be created through a suitable combination of VUV radiation and CRA modification, which have almost the same release forces on polyisoprene and polyacrylate adhesive tapes. This is not possible with the state-of-the-art technology using CRA alone.

Preference is also given to a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface that is specified above or below as preferred), the modified surface having a layer thickness in the range from> 100 to <6000 nm, preferably in the range from> 300 to <3000 nm, and / or the modified surface with a higher separation force compared to the adhesive surface of a reference adhesive tape, in comparison with the unmodified silicone, has two or more surface areas which have differently increased separation forces compared to the unmodified silicone.

With the preferred variant of the present invention, where the modified surface with a higher separation force compared to the adhesive surface of a reference adhesive tape, compared with the unmodified silicone, has two or more surface areas which have differently increased separation forces compared to the unmodified silicone, it is possible to provide modified surfaces with areas of specifically adjusted, different separation forces. This is particularly advantageous when surfaces with areas of different adhesive properties are desired, for example areas in which a strongly adhesive surface sticks relatively less, so that in these areas the surface can be touched and handled without problems ("handles") without it comes to an undesirable adhesive contact.

The present invention also relates to a method for producing a silicone with a modified surface, preferably a preferred silicone according to the invention with a modified surface specified above, comprising the steps:

(V1) providing silicone, preferably at least partially crosslinked silicone elastomer, and (V2) irradiating at least part of the surface of the silicone from step (V1) with UV radiation of at least one wavelength in the range from> 50 nm to <380 nm, preferably in the range from> 150 nm to <200 nm, more preferably in Range from> 150 to <190 nm, in an atmosphere with an oxygen content in the range from> 0 to <22% by volume, preferably in the range from> 10 to <21% by volume, so that a silicone according to the invention with modified surface results.

With regard to preferred configurations and possible combinations of preferred configurations of the uses according to the invention, the explanations given above for the silicone according to the invention with a modified surface apply accordingly (if necessary, in a corresponding manner), and vice versa.

In the method according to the invention, the irradiation in step (V2) preferably takes place by means of an excimer lamp or a low-pressure mercury lamp as the radiation source, since these lamps have proven to be particularly suitable and easy to handle for the method according to the invention.

In addition to the radiation in the range of 185 nm, low-pressure mercury lamps have a radiation band at 254 nm. This radiation band can generally have an advantageous effect on the silicone elastomer activation in step (V2). For example, ozone is broken down by the 254 nm radiation and partially converted into atomic, reactive oxygen. The latter can be used advantageously for activation. For the calculation of the radiation dose (as for the entire text), only radiation with a wavelength <250 nm is taken into account. This means that the dose introduced due to the 254 nm band is not included in the calculation of the dose to be used according to the invention. If lasers, preferably excimer lasers, are used for irradiation, they are preferably selected so that their pulse energies are below the ablation threshold of the silicones to be irradiated. Continuous lasers are preferred.

Alternatively, the silicone elastomer can be treated with a plasma, which also emits radiation in the above-mentioned wavelength range. Plasmas consisting of a hydrogen / oxygen mixture are preferred. Hydrogen-containing plasmas are particularly preferred here. In the method according to the invention, one radiation source (as described above) or several radiation sources can be used, for example as a battery of several radiation sources (as described above), which can be the same or different (different types of radiation). Achieving the desired effect of the method according to the invention, ie the production of a silicone with a modified surface which has an (defined above) proportion of silanol groups on the surface of the modified surface compared to the unmodified silicone, can be based on the following parameters in more detail below The following can be influenced: - The wavelength of the UV radiation, with shorter wavelengths resulting in a lower penetration depth and thus a lower modification depth due to the higher absorption cross-section, but at the same time leading to a more modified surface (closer to the surface, stronger crosslinking of the silicone) and thus to a stronger one Increase in the separation force of the modified surface, preferably compared to the adhesive surface of a reference adhesive tape. According to the invention, it is therefore preferred to use a wavelength of the UV radiation used in the range from> 50 nm to <380 nm, preferably in the range from> 150 nm to <200 nm, more preferably in the range from> 150 to <190 nm.

The distance of the radiation source from the surface of the silicone to be irradiated, with a smaller distance to a higher radiation dose and thus to a greater increase in the separating force of the modified surface (closer to the surface, stronger crosslinking of the silicone), preferably compared to the adhesive surface of a reference adhesive tape , leads. According to the invention, a distance between the radiation source and the surface of the silicone to be irradiated is preferred in the range from 0.5 to 50 mm, preferably in the range from 0.5 to 10 mm, particularly preferably in the range from 1 to 5 mm.

The irradiation power of the radiation source or radiation sources used, with higher irradiation powers preferably leading to a higher radiation dose and thus to a greater increase in the separating force of the modified surface (closer to the surface, stronger cross-linking of the silicone), preferably compared to the adhesive surface of a reference adhesive tape. According to the invention An optical output power in the range from 0.1 to 2.0 W / cm, preferably in the range from 0.15 to 0.8 W / cm, is preferred as the irradiation power of the radiation source or radiation sources used.

The duration of the irradiation of the surface of the silicone, with a longer irradiation leading to a higher radiation dose and thus to a greater increase in the

Separation force of the modified surface (closer to the surface, stronger crosslinking of the silicone), preferably compared to the adhesive surface of a reference adhesive tape. In practice, the duration of the irradiation is often determined by the relative movement between the surface of the silicone to be modified and the VUV radiation source. In the case of industrially particularly relevant web material, the duration is defined by the web speed. Web speeds in the range from 1 to 1000 m / min, preferably in the range from 50 to 500 m / min, particularly preferably in the range from 60 to 400 m / min, are preferred according to the invention.

The (maximum) radiation intensity on the surface of the silicone, with a greater radiation intensity leading to a higher radiation dose and thus to a greater increase in the separating force of the modified surface (closer to the surface, stronger cross-linking of the silicone), preferably compared to the adhesive surface of a reference adhesive tape, leads. According to the invention, maximum radiation intensities on the irradiated silicone surface in the range from 0.01 to 1000 mW / cm ² , preferably in the range from 0.03 to 200 mW / cm ² , particularly preferably in the range from 0.1 to 100 mW / cm ² and very particularly preferably in the range from 1.0 to 40 mW / cm ² .

The irradiation dose as an integral of the location- and time-dependent irradiance (“mean irradiation dose”) over the duration of the irradiation, with a larger irradiation dose leading to a greater increase in the separating force of the modified

Surface (closer to the surface, stronger cross-linking of the silicone), preferably opposite the adhesive surface of a reference adhesive tape. For radiation doses preferred according to the invention, see below.

The oxygen partial pressure in the working atmosphere or the volume fraction of oxygen in the working atmosphere. A method according to the invention is preferred in which the working atmosphere has an oxygen content in the range from> 0 to <22% by volume, preferably in the range from> 10 to <22% by volume, particularly preferably in the range from> 15 to <21 , 0% by volume and very particularly preferably in the range from> 20 to <21 vol .-%, the rest of the working atmosphere to 100 vol .-% preferably being occupied by an inert gas, preferably selected from the group consisting of noble gases, nitrogen, carbon dioxide and mixtures thereof. In a preferred variant of the method according to the invention, the working atmosphere contains only air from the ambient atmosphere and / or is provided from a compressed air tank or generator.

A method according to the invention for producing a silicone with a modified surface is preferred, the irradiation at an average radiation dose in the range from> 0.01 to <10 mJ / cm ² , preferably in the range from> 0.02 to <9 mJ / cm ² , particularly preferably in the range from> 0.03 to <8 mJ / cm ² , more preferably in the range from> 0.035 to <2.2 mJ / cm ² and very particularly preferably in the range from> 0.035 to <0.99 mJ / cm ^{2 is} carried out. As described, the absorption behavior of silicones for UV radiation depends on the wavelength of the incident light. For a rough orientation, the absorption spectrum B from Fig. 3 from the publication by Cefalas et al. “Absorbance and outgasing of photoresist polymeric materials for UV lithography below 193 nm including 157 nm lithography, Microelectron. Closely. 53, No. 1 -4, 2000, pp. 123-126 “decadic absorption coefficients A (l) for radiation of wavelength l = 172 nm of about 3.5 mht ¹ and A (l) for radiation of wavelength l = 185 nm 0.5 mht ^{1 can be} taken. The degree of absorption of an upper layer layer of d = 0.01 μm probed by XPS measurement is calculated according to

Degree of absorption = 1 - io ^{A (A) * d} The degree of absorption indicates how high the proportion of absorbed photons is in relation to the radiated photons. In the case of 185 nm radiation, the proportion calculated using the above information is 1.1%. In contrast, in the case of 172 nm radiation, a 7 times higher value of 7.7% is calculated.

Under the common assumption that only absorbed photons can have an effect in the absorbing material (basic photochemical law of Grotthus-Draper) So it can be assumed that with an identical number of irradiated photons (identical radiation dose) 172 nm photons have a greater effect than 185 nm photons. From other publications by Skurat and Dorofeev “The transformation of organic polymers during the Illumination by 147.0 and 123.6 nm light, Angew. Macromol. Chemie 216, No. 1, 1994, pp. 205-224 "and Dever et al." Effects of vacuum ultraviolet radiation on DC93-500 Silicone, Journal of Spacecraft and Rockets, No. 43, 2006, pp. 386- 392 ”, similar but not identical absorption coefficients can be calculated depending on the wavelength, so that the above calculation example only reflects a trend. The rule that 185 nm photons are less strongly absorbed than 172 nm photons is always true.

Furthermore, 172 nm radiation from xenon excimer lamps is not monochromatic, but the emission occurs spectrally with a half width of 14 nm, so that on the one hand there is a spectrally different absorption of the radiation by oxygen and on the other hand a spectrally different absorption of the radiation by the silicone. In contrast to the assumption in the calculation example of monochromatic 172 nm radiation, the degree of absorption of a silicone layer is reduced if the absorption is considered spectrally (and thus more realistic). The rule that 185 nm photons are less strongly absorbed than radiation emitted from xenon excimer lamps is always true.

As a result, this means that the radiation dose is an indication of the desired effects, but does not only allow statements about the effect achieved. In practice, the type of radiation plays a major role (see also above), so the same dose irradiated by a xenon excimer leads to a stronger modification of the surface of a silicone than the same dose, provided that it causes longer-wave radiation from a wave has been. It is therefore possible according to the invention, the change in the release force of a silicone according to the invention with a modified surface or a composite material according to the invention caused by the method according to the invention in a desired manner compared to an adhesive in contact with the modified surface of the silicone according to the invention and / or compared to an adhesive with the modified surface of the to influence or specifically control the adhesive layer in contact with the silicone according to the invention, preferably with respect to a pressure-sensitive adhesive tape in contact with the modified surface of the silicone according to the invention. The method according to the invention for producing a silicone with a modified surface is preferably carried out at atmospheric pressure or at (compared to normal pressure) reduced pressure (low pressure).

It is preferred that the method according to the invention for producing a silicone with a modified surface is carried out at a defined relative humidity, preferably at a relative humidity in the range from 20 to 80%, more preferably in the range from 40 to 60%.

The process according to the invention for producing a silicone with a modified surface can be carried out at room temperature, preferably at a temperature in the range from 15 to 25 ° C, more preferably at a temperature in the range from 18 to 22 ° C.

For the sample temperature (the samples comprising the silicone used in the method according to the invention) it is preferred that this is <70 ° C, more preferably <50 ° C and particularly preferably <40 ° C. The preferred process parameters listed above and below can be selected depending on the process requirements, combinations of the preferred process parameters with one another being possible. This makes it possible to ideally adapt the method to desired or particularly preferred manufacturing requirements.

It was surprisingly found in our own experiments that even particularly small mean radiation doses of radiation in the range specified above or in the preferred range specified above lead to an increase in the release force of the modified surface compared to pressure-sensitive adhesives, but not yet significantly change the surface energy becomes. This effect of the modification, preferably the modification by UV radiation in the specified wavelength range, appears to be due to the introduction of silanol groups for the purposes of this text. This is an effect which - in contrast to conventional plasma processes - is noticeable or can be detected not just a few nanometers, but up to a depth in the range of <3 μm below the irradiated surface of the silicone. Because siliconizations are typically applied with an application weight of a few g / m ² , ie a layer thickness of a few μm, the UV irradiation according to the invention thus in most cases modifies a significant part of such a silicon material, ie the modified surface of such a material Then silicone makes you a considerable proportion of the total silicone forming such a siliconization (ie silicone coating).

The determination or measurement of the (maximum) irradiance or the average radiation dose to be used in the method according to the invention is not trivial due to the complexity of the measurement (apparatus) in the radiation measurement and the relatively low average radiation dose to be used in the present case:

For this, reference is made to the German patent application with the official file number DE 10 2018 108 881 .7 for determining the radiation dose.

With the above information regarding: the effects to be achieved according to the invention in connection with the modified silicone surface,

the parameters relevant to achieving the effects according to the invention on the modified surface of the silicone,

- the above description of the type and direction in which the relevant parameters influence the effects according to the invention on the modified surface,

- the above description of the model calculation of the (maximum) irradiance to be used according to the invention and / or the mean radiation dose to be used according to the invention and - the practical exemplary embodiments given in this text, the person skilled in the art is able to carry out the teaching of the present invention to the full extent.

Also preferred is a method according to the invention for producing a silicone with a modified surface (or a method according to the invention, indicated above or below as preferred, for producing a silicone with a modified surface) whereby different surface areas of the silicone are irradiated with different radiation doses from the radiation dose range specified (for the method according to the invention), and / or the silicone in step (V1) comprises a carrier material and is preferably applied to a carrier material (preferably the modified surface of the silicone facing away from the carrier material).

To carry out the method according to the invention, the radiation sources can therefore be positioned parallel to one another or in any desired orientation. The distances between the respective radiation sources and the surface or surfaces to be irradiated can be the same for all radiation sources or different for individual, multiple or all radiation sources. If individual, several or all radiation sources are arranged at different distances from the surface or surfaces to be irradiated, local areas of the surfaces to be irradiated can be treated with different radiation doses, whereby, for example, surface areas with different adhesive properties can be generated. Different distances between the radiation sources and the surface or surfaces can also be useful for combining different radiation wavelengths. Using suitable technical measures to set the radiation dose (e.g. distance, treatment speed, dimming the beam source, multi-stage irradiation with different doses or oxygen partial pressure) and the oxygen partial pressure, selected areas of flat siliconization (different surface areas of the silicone with modified surface) can be made different treat (irradiate) and thus provide any separating force.

Using mask techniques, (only) selected areas of a flat siliconization can be irradiated according to the method according to the invention and thus provided with a higher separation force. If coherent radiation (by excimer laser) is used, areas of the siliconization can also be irradiated in a targeted manner without mask technology. In this case, the beam is specifically shaped and directed to the desired areas of the surface, e.g. with the help of scanner mirrors. The present invention also relates to a silicone with a modified surface, preferably with a surface modified by UV radiation, produced or producible by a method according to the invention for producing a silicone with a modified surface (or according to a production method according to the invention specified above or below as preferred a silicone with a modified surface).

With regard to preferred configurations and possible combinations of preferred configurations of the silicone with a modified surface produced or which can be produced by the method according to the invention, the explanations given above for the silicone according to the invention with a modified surface and for the method according to the invention for producing a silicone with a modified surface apply accordingly (if necessary, analogously) , and vice versa.

If the silicone comprises a carrier material in step (V1) and is preferably applied to a carrier material, a composite material according to the invention can preferably be produced in this way (see below). The carrier materials described in more detail below, which can be part of the composite material according to the invention, can preferably be used as carrier material.

The present invention therefore also relates to a method for producing a composite material, comprising the steps

(V1A) providing silicone, preferably at least partially crosslinked silicone elastomer, comprising a carrier material (the silicone preferably being present as a coating on at least one surface of the carrier material),

(V2) irradiating at least part of the surface of the silicone from step (V1) with UV radiation of at least one wavelength in the range from> 50 nm to <380 nm, preferably in the range from> 150 nm to <220 nm, in an atmosphere with an oxygen content in the range from> 0 to <22% by volume, preferably in the range from> 10 to <21% by volume, so that a composite material comprising silicone according to the invention with a modified surface results.

With regard to preferred configurations and possible combinations of preferred configurations of the method according to the invention for producing a composite material, the following apply to the silicone according to the invention with a modified surface and to the Process according to the invention for producing a silicone with a modified surface in accordance with the explanations given above (if appropriate, in analogy) and vice versa.

The silicone provided in step (V1A) comprising a carrier material can be produced in a manner known per se, in particular by applying the silicone or a silicone known per se to a suitable carrier material, preferably to a carrier material defined in more detail below. This process is also known as "siliconizing". In this way, according to the method according to the invention, a permanent composite material can be produced which is suitable, among other things, for carrying out a pull-off test (for more details, see above).

The present invention also relates to a composite material, produced or producible by a method according to the invention for producing a composite material (or according to a method according to the invention for producing a composite material specified above or below as preferred). With regard to preferred configurations and possible combinations of preferred configurations of the composite material produced or produced by a method according to the invention, the following apply to the silicone according to the invention with a modified surface, to the method according to the invention for producing a silicone with a modified surface and to the method according to the invention for producing a composite material the explanations given above accordingly (if necessary, analogously), and vice versa.

Step (V2A) of the above-specified method for producing a composite material is preferably followed by one or more further steps, preferably rolling the produced composite material into a roll and / or coating the produced composite material with one or more pressure-sensitive adhesives. Depending on the intended use, the carrier material is coated with one or more pressure-sensitive adhesives and / or the modified surface of the silicone is coated with one or more pressure-sensitive adhesives.

The present invention also relates to a composite material comprising silicone with a modified surface, preferably with a surface modified by UV radiation (or a silicone according to the invention with a modified surface specified above or below as preferred), and a carrier material, wherein the carrier material is preferably selected from the group consisting of

Polyester, preferably polyethylene terephthalate, particularly preferably biaxially oriented polyethylene terephthalate;

Polyethylene; preferably high density polyethylene and low density polyethylene; - Polypropylene, preferably monoaxially stretched polypropylene, biaxially stretched

Polypropylene, extruded polypropylene;

Polybutylene;

Polyvinyl chloride;

Paper, preferably glassine paper, clay coated paper, kraft paper, machine smooth paper and polyolefin coated paper;

Metal, preferably aluminum; such as

Mixtures of the aforementioned carrier materials.

A composite material according to the invention (or a composite material according to the invention specified above or below as preferred) is preferred, comprising a silicone according to the invention with a modified surface, preferably with a surface modified by UV radiation, in the form of a web or a film, preferably a thickness in the range from> 0.5 to <200 μm, which on at least one of its surfaces to an area proportion of> 50%, preferably> 75%, particularly preferably completely, with the silicone according to the invention with a modified surface, preferably with UV radiation modified surface, is coated, wherein the layer comprising the silicone with surface modified by UV radiation preferably has a layer thickness in the range from> 0.1 to <20 μm on the composite material. A composite material according to the invention (or a composite material according to the invention specified above or below as preferred) is also preferred, in addition comprising an adhesive in contact with the modified surface of the silicone and / or an adhesive layer in contact with the modified surface of the silicone.

The carrier material of the composite material according to the invention can be coated on one of its surfaces or on two or more of its surfaces (if present) with the silicone with a modified surface, for example on the front and back of a web or film. If the carrier material is coated on two or more of its surfaces with silicone with a modified surface, the modified surfaces of the silicone can have the same or different separation forces. In this way, for example, a release film or a release liner can be made available which has different release forces on its upper and lower side.

The present invention also relates to the use of a silicone according to the invention with a modified surface (or a silicone according to the invention with a modified surface specified above or below as preferred) in non-stick coatings, preferably as an adhesive force regulator, preferably in non-stick coatings selected from the group consisting of:

Non-stick coatings for self-adhesive products, preferably selected from the group consisting of self-adhesive labels, adhesive tapes, self-adhesive decorative films, self-adhesive protective films, plasters and hygiene products, and

Non-stick coatings for idler papers, rubber or plastic production, tire molds and baking paper.

With regard to preferred embodiments and possible combinations of preferred embodiments of the inventive use of a silicone according to the invention with a modified surface, the following apply to the silicone according to the invention with a modified surface, for the method according to the invention for producing a silicone with a modified surface, for the method according to the invention for producing a composite material, for the composite material produced or producible by a method according to the invention as well as the explanations given above for the composite material according to the invention accordingly (if necessary in a corresponding manner), and vice versa. The present invention also relates to the use of a composite material according to the invention or a composite material produced or produced by a process according to the invention (or a corresponding composite material according to the invention specified above or below as preferred) as a release film and / or release liner for substances with a high surface area Adhesiveness, preferably selected from the group consisting of

Self-adhesive products, preferably selected from the group consisting of self-adhesive labels, adhesive tapes, self-adhesive decorative films, self-adhesive protective films, plasters and hygiene products; preferably adhesive tapes, particularly preferably double-sided adhesive tapes;

Substances with high surface adhesion, preferably selected from the group consisting of unreacted resins and prepregs, highly viscous media, preferably selected from the group consisting of adhesives, paints and printing inks, and self-adhesive semi-finished products, preferably selected from the group consisting of attachments in the exterior of motor vehicles , preferably trim strips and logos, and attachments in the interior of motor vehicles.

With regard to preferred configurations and possible combinations of preferred configurations of the use according to the invention of a composite material according to the invention, the following apply to the silicone according to the invention with a modified surface, for the method according to the invention for producing a silicone with a modified surface, for the method according to the invention for producing a composite material, for the according to a Composite material produced or producible according to the method according to the invention, for the composite material according to the invention and for the use according to the invention of a silicone with a modified surface, corresponding to the explanations given above (if appropriate, analogously) and vice versa.

In the context of the present invention, the term “prepregs” is understood - in accordance with the usual understanding in the specialist world - to be understood as meaning pre-impregnated textile fiber matrix semi-finished products that are used to manufacture Position of components are cured under temperature and pressure. The reaction resins consist of a mostly highly viscous, but not yet polymerized, thermosetting plastic matrix, which is mainly used in lightweight construction. The fibers contained can be present as a pure unidirectional layer, as a fabric or scrim. Prepreg, for example, is supplied in web form, wound on rolls. The term prepreg includes not only unidirectionally reinforced or flat semi-finished products, but also other preforms of basically any shape that, in the broadest sense, consist of an uncured thermoset matrix filled with fibers. The matrix is in the partially networked, so-called B-stage, and is pasty to solid, but can be liquefied again by heating.

The invention is described in more detail below with reference to the examples and the figures.

Examples:

In the following examples, at% data always relate to the total number of atoms that can be measured with ESCA - unless otherwise stated.

Material example 1: siliconizations:

Silicone S: Unless otherwise stated, the Easy Release silicone treatment Separacon 9160-60 on glassine paper (160 g / m ² ) from MariaSoell (Nidda-Eichelsdorf) was used. This is a silicone system that does not cross-link UV during production, but rather a platinum-catalyzed (thermally activated) cross-linking silicone system. The application weight was 3 g / m ² .

Irradiation example 1: vacuum-UV modification of siliconizations

The siliconizations are irradiated by means of a low-pressure mercury lamp (UVX 120 4C S 19/670 Co, Hönle) with an irradiation power: 0.176 W / cm (10 W at 568 mm light length, manufacturer information) using the following parameter sets (partly a selection from them):

Parameter set P2 (according to the invention): (working atmosphere with N2 proportion: 79 vol .-%, O2 proportion 21 vol .-%, distance 10 mm, travel speed 1.01 m / min) or Parameter set P3 (according to the invention): (working atmosphere with ISfe content: 79 vol .-%, O2 fraction 21 vol .-%, distance 10 mm, travel speed 1, 68 m / min) or

Parameter set P4 (according to the invention): (working atmosphere with ISfe content: 79% by volume, O2 content 21% by volume, distance 10 mm, travel speed 1.83 m / min) or parameter set P5 (according to the invention): (working atmosphere with ISfe content: 79% by volume, O2 content 21% by volume, distance 10 mm, travel speed 7.5 m / min) irradiated.

Parameter set P6 (according to the invention): (working atmosphere with ISfe content: 79% by volume, O2 content 21% by volume, distance 30 mm, travel speed 6.8 m / min) irradiated.

This siliconization was also carried out using a xenon excimer lamp (XERADEX L40 / 375 / DB-AZ48 / 90, Osram) with a 375 mm light length, an irradiation power:

0.5 W / cm and an irradiance of 40 mW / cm ² on the emitter surface (manufacturer information) 0 irradiated using the following parameter sets:

Parameter set P1 (not according to the invention): (working atmosphere with ISfe content: 95% by volume, O2 content 5% by volume, distance 50 mm, travel speed 3 m / min) irradiated. As a comparative example, the silicone S1 -PET from the application with the German official file number DE 10 2018 108 881 .7 was reworked here. The production took place as described in the application mentioned.

Parameter set P7 (according to the invention): (working atmosphere with ISfe content: 79% by volume, O2 content 21% by volume, distance 30 mm, travel speed 19.2 m / min) irradiated. Values for the mean radiation dose, the maximum and the mean radiation power, are determined with the help of the ray tracing software as described in the German patent application with the official file number DE 10 2018 108 881 .7. In case of doubt, a translation distance of 20 cm symmetrical and orthogonal to the lamp axis is taken into account for the simulation of the mean radiant power. The values listed in Table 1 result for the parameter sets. Also included is the reference (“Ref), which corresponds to a sample that was irradiated with a radiation dose of 0 mJ / cm ² . Table 1: Simulation result for mean radiation doses and mean radiation powers of the parameter sets P1-P7

Derivatization example 1: For this chemical gas phase derivatization, the sample was placed in a Petri dish with a volume of 75 cm ³ and a diameter of 100 mm and gaseous chlorodimethyl (3,3,3-trifluoropropyl) silane (97%, chemical formula: CI- ( CH3) ₂ Si- (CH ₂ ) ₂ CF3, FZ: 3, CAS 1481 -41 -0, but GmbH) exposed. For this purpose, a small aluminum dish with 0.15 enr ^{3 of} the silane was placed in the Petri dish and the arrangement was heated in a gas-tight convection chamber oven (KU15 / 06 / A, Thermconcept Dr. Fischer GmbH & Co. KG). The oven was heated from 20 to 105 ° C. within 40 minutes and the temperature was kept constant at 105 ° C. for 6 hours. The cooling to 30 ° C. was uncontrolled. The sample was then analyzed using ESCA. Derivatization example 2:

This chemical gas phase derivatization of the samples was carried out in accordance with the experimental description in the publication by Munief et. al (Munief, Heib, F., Hempel, F, Lu, X., Schwartz, M., Pachauri, V., Hempelmann, R., Schmitt, M., Ingebrandt. S., Langmuir 2018 34 (35 ), 10217-10229, experiment on p. 10219), but using 1 H, 1 H, 2H, 2H-perfluorooctyldimethylchlorosilane (97%, chemical formula: CI- (CH3) ₂ Si- (CH ₂ ) ₂ (CF ₂ ) 5CF3, FZ: 13, CAS 102488-47-1, but GmbH) (instead of 1H, 1H, 2H, 2H-per- fluorooctyl-trichlorosilane, chemical formula: Cl3Si- (CH ₂ ) 2 (CF ₂ ) 5CF3) and the removal of adsorbed residues after the silanization was carried out only as described with the aid of nitrogen gas, which was found to be sufficient.

Measurement example 1: Determination of the element composition, determination of the fluorine concentration - calculation of the silanol concentration

ESCA analysis: The surfaces were examined analytically with regard to their element concentration (based on all atoms of the surface layer except hydrogen and helium). The high detection sensitivity of the method is element-specific and dependent on the measurement parameters and is around 1000 ppm for silicon and carbon and around 250 ppm for fluorine. The information depth is approx. 10 nm. The ESCA examinations were carried out with a Kratos-Axis-Ultra system. Parameters: hybrid mode, acceptance angle of photoelectrons 0 °, monochromatized AI ka excitation, CAE mode with 80 eV pass energy, a step size of 0.5 eV and an acquisition time of 0.5 s in the overview spectra, elliptical analysis surface with main axes of 0.7 mm and 0.3 mm, neutralization of the samples with low-energy electrons. In the case of preceding derivatisation experiments, F 1s spectra were recorded. To reduce the detection sensitivity in the F 1 s concentration, the F 1 s spectra were recorded with an extended measurement time (0.1 eV step size, 4.5 s acquisition time, 80 eV passenger energy). The fluorine concentrations were therefore quantified using the combined overview and F 1s spectra.

From the quotient of the measured fluorine concentration in at% based on the atoms recorded by ESCA and the fluorine number FZ of the derivatization reagent used, the silanol concentration in at% based on the atoms recorded by ESCA is calculated (in fact, we only consider the 0 atom here). The C, O and Si atoms of the derivatization reagent additionally incorporated by the derivatization can be rounded up the low silanol group concentrations up to 0.135 at% are neglected in the evaluation.

The increased fluorine or silanol concentration for irradiated samples compared to the unpunished reference is calculated from the difference between these values for the irradiated less the non-irradiated sample.

The reduction in the C concentration for irradiated samples compared to the unpunished reference is calculated from the difference in the value for the C concentration for the unirradiated sample minus the value for the C concentration for the irradiated sample. The ESCA experiments to determine the reduced C concentration were each determined (for the samples irradiated using parameters P1-P7 and the non-irradiated reference) without prior derivatization of the samples. ESCA experiments after derivatisation were carried out using the same samples, which were irradiated using identical parameters P1-P7, and other identical, non-irradiated reference samples. In other words, after an ESCA experiment, the samples were not subjected to further experiments, instead samples were freshly prepared.

Measurement example 2: Determination and analysis of the depth profile of silanol groups

The siliconization is on the back of a rigid, low-temperature stable carrier, z. B. an aluminum block, glued. This specimen is clamped in an ultramicrotome and carefully aligned with the cutting plane. While cooling with liquid nitrogen, a maximum of 30 microtome sections with a thickness of 100 nm are prepared and collected and numbered in sequence (starting with 1).

These sections are now characterized according to derivatization example 1 (or derivatization example 2 if less than 80 ppm of silanol groups are to be detected) and measurement example 1, the number of microtome sections to be analyzed being based on the result of measurement example 1 as follows: a silicon element concentration is measured that deviates by at least 5 at .-% from the value measured on the surface, the previous microtome section should be the last section to be analyzed, because this is an indication that the substrate has been at least partially exposed.

The data (silanol concentration as a function of depth) are calculated using an exponential function y = A1 * e ^{(x / t1)} + yO (equation A) with y the silanol concentration in at .-%, A1 the constant for the surface area of the silanol groups in at-%, x the depth in nm (to be calculated from 100 nm * ('number of the microtome section' -1), yO the offset in at .-% and t1, a constant, fitted in nm. The constant t1 corresponds to the mean depth range of the modification. The layer thickness of the modified area as above defined (corresponds to the layer thickness of the modified surface) is calculated according to

Layer thickness of the modified area = 3 * t1 (equation B)

The Fitroutine stored in Origin for the above is used. Exponential function used with offset (name: ExpDecl in Origin Pro2016). The offset yO obtained from the fit result gives the basic contribution (based on the measured silanol content) of the unmodified material.

Measurement example 3: Separation force measurement

Before the adhesive tapes were applied, samples modified according to irradiation example 1 were initially stored at room temperature for 1 day. To apply the adhesive tapes to the surfaces modified according to the invention or the reference surfaces, the adhesive tapes were each pressed 10 times with the pressure roller at an unwinding speed of approx. 1 cm / s and the glued samples were then stored at 40 ° C. for a further 20 hours. For this purpose, the bonded samples were loaded between two flat metal plates with a pressure of approx. 70 g / cm ² . Before the determination of the adhesive force, the samples were stored again for approx. 4 h without stress at room temperature.

The material according to the invention (or the unirradiated silicone elastomer on paper as a reference) and the pressure-sensitive adhesive tape were then separated and each in a 180 ° peel test based on the FINAT test method FTM 10 (see FINAT Technical Handbook, 9th edition 2014) the necessary separation force was measured over a travel distance of 175 mm at a test speed of 500 mm / min, whereby the first 25 mm and the last 10 mm were not evaluated.

The Tesa® adhesive tape 7475 (acrylate-based pressure-sensitive adhesive) was used, an adhesive tape intended according to FINAT FMT for the characterization of siliconizations. The separation force increase factor is calculated as the quotient of the measured separation value and the reference separation value (non-irradiated sample).

Results:

Example table 1 to example table 5 show the results for material example 1 and derivatization example 1 and 2 with the name of silicone, irradiation parameter set and measurement specification.

Example table 1: Results for silicone S1 from German patent application with the official file number DE 10 2018 108 881 .7 after irradiation using process P1

Example table 2: Results for silicone S after irradiation using process P2-P7

Example table 3: Results for silicone S after irradiation using process P2-P5

Example table 4: Results for silicone S after irradiation using process P6-P7

Example table 5: Results for silicone S after irradiation using process P2-P7 and the non-irradiated reference silicone S "Ref"

Example depth profile: determination of the fluorine concentration as a function of the depth

The siliconization “S” is irradiated according to parameter set P4 from irradiation example 1 (according to the invention). Following measurement example 2, a total of 32 microtome sections with a thickness of 100 nm are prepared and the fluorine depth profile is analyzed according to the instructions in measurement example 2.

The deviations of the silicon content from the surface value (measured in section 1) as well as the F concentrations after derivatisation and measured by ESCA as described in measurement examples 1 and 2 depending on the depth are as follows:

Silicon content of cut 1 in at .-% .: 23.42, silicon content of cut 31 in at .-% .: 17.74 at .-%.

Analysis according to measurement example 2 results in a basic contribution (offset yO) of 0.0404 at .-% fluorine. This results in a value of 0.162 atom% fluorine for the contribution to the surface caused by UV modification.

The mean depth range (constant t1 according to the analysis according to measurement example 2) is 833 nm. The layer thickness of the modified area is calculated according to equation B in measurement example 2: layer thickness of the modified area = 3 * t1 = 2499 nm.

Claims

Patent claims:

1. Silicone with a modified surface, the concentration of silanol groups on the modified surface compared to the concentration of silanol groups in the unmodified silicone by 0.0015 at% to 0.13 at%, preferably by 0.0015 at% to 0.08 at%, is increased, measured by ESCA after chemical gas phase derivatization and based on the total number of atoms detected by ESCA.

2. The silicone of claim 1, wherein the modified surface has a carbon content that is <0.1 at% lower than that of the unmodified silicone, measured using ESCA and based on the total number of atoms detected using ESCA.

3. Silicone according to claim 1 or 2, wherein the modified surface compared with the unmodified silicone, measured with a peel test, has a higher release force compared to the adhesive surface of a reference adhesive tape, the reference tape preferably being TESA 07475 and where the release force increase in the range> 10% to <579%, preferably> 20% to <299%, particularly preferably> 28% to <299%, based on the release force of the unmodified silicone.

4. Silicone according to one of the preceding claims, wherein the separation force measured with a peel test against the adhesive surface of a reference adhesive tape, the reference tape preferably being TESA 07475, in the range of 0.018 N / cm to 1.2 N / cm, preferably 0.02 N / cm to 0.75 N / cm, particularly preferably 0.031 N / cm to 0.38 N / cm.

5. Silicone according to one of the preceding claims, wherein the unmodified silicone is based on a dimethylsiloxane, a phenylmethylsiloxane and / or diphenylsiloxane and their copolymers.

6. Silicone according to one of the preceding claims, wherein the unmodified silicone does not contain any controlled release additives, in particular no MQ resins and no pyrogenic silicas.

7. Silicone according to one of the preceding claims, wherein the unmodified silicone is a silicone elastomer which is produced from an addition reaction, preferably a UV radiation-induced addition reaction, or more preferably a transition metal-catalyzed addition reaction, and very particularly preferably a Pt-catalyzed addition ons reaction has arisen.

8. Silicone according to one of the preceding claims, wherein the modified surface has a layer thickness in the range from> 100 to <6000 nm, preferably in the range from> 300 to <3000 nm, and / or - the modified surface with higher separation force compared to the adhesive surface of a reference adhesive tape, in comparison with the unmodified silicone, has two or more surface areas which have differently increased separation forces compared to the unmodified silicone.

9. A composite material comprising silicone with a modified surface according to any one of claims 1 to 8, and a carrier material, wherein the carrier material is preferably selected from the group consisting of

Polyester, preferably polyethylene terephthalate, particularly preferably biaxially oriented polyethylene terephthalate; - polyethylene; preferably high density polyethylene and low density polyethylene;

Polypropylene, preferably monoaxially stretched polypropylene, biaxially stretched polypropylene, extruded polypropylene;

Polybutylene; - polyvinyl chloride;

Paper, preferably glassine paper, clay coated paper, kraft paper, machine smooth paper, and polyolefin coated paper;

Metal, preferably aluminum; such as

Mixtures of the aforementioned carrier materials.

10. Composite material according to claim 9 in the form of a web or a film, preferably a thickness in the range from> 0.5 to <200 μm, which on at least one of its surfaces to an area proportion of> 50%, preferably> 75%, especially preferably completely coated with the silicone with a modified surface, the layer comprising the silicone with a modified surface preferably having a layer thickness in the range from> 0.1 to 20 20 μm, preferably 3,5 0.2 to 3.5 μm on the composite material having.

11. The composite material according to claim 9 or 10, additionally comprising an adhesive in contact with the modified surface of the silicone and / or an adhesive layer in contact with the modified surface of the silicone.

12. Use of a silicone according to one of claims 1 to 8 in non-stick coatings, preferably as an adhesive force regulator, preferably in non-stick coatings selected from the group consisting of:

Non-stick coatings for loose-leaf papers, rubber or plastic production, tire molds and baking paper.

13. Use of a composite material according to one of claims 9 to 11 as a release film and / or release liner for substances with high surface adhesion, preferably selected from the group consisting of

Substances with high surface adhesion, preferably selected from the group consisting of unreacted resins and prepregs, highly viscous media, preferably selected from the group consisting of adhesives, paints and printing inks, and self-adhesive semi-finished products, preferably selected from the group consisting of attachments in the vehicle exterior, preferably trim strips and logos, and attachments in the vehicle interior.

14. A method for producing a silicone with a modified surface, comprising the steps of:

(V1) providing silicone, preferably at least partially crosslinked silicone elastomer, and

(V2) irradiating at least part of the surface of the silicone from step (V1) with UV radiation of at least one wavelength in the range from> 50 nm to <380 nm, preferably in the range from> 150 nm to <220 nm, in an atmosphere with an oxygen content in the range from> 0 to

<22% by volume, preferably in the range from> 10 to <21% by volume, so that a silicone with a modified surface according to one of claims 1 to 8 results.

15. The method according to claim 14 for producing a silicone with a modified surface, the irradiation at an average radiation dose in the range from> 0.01 to <10 mJ / cm ² , preferably in the range from> 0.02 to <9 mJ / cm ² , particularly preferably in the range from 0.03 to 8 mJ / cm ² , more preferably in the range from 0.035 to 2.2 mJ / cm ² and very particularly preferably in the range from 0.035 to 0.99 mJ / cm ² .