HK1196799A - Irradiating and molding unit - Google Patents

Description

Irradiation and shaping unit

The present invention relates to an irradiation and shaping unit having one or more uv light sources for curing a photocurable polymer composition. The irradiation and molding unit of the present invention enables polymer moldings or polymer coverings, especially silicone moldings, to be produced highly efficiently in a continuous or batch process. The irradiation and shaping unit according to the invention increases in particular the lifetime of transparent castings originating from polymeric shaping materials, in particular from polyacrylates. Polyacrylate moldings exposed to direct radiation (for example conventional UV light sources equipped with mercury lamps, having a broad radiation spectrum) deform, discolor after several moldings, reduce their UV transmittance at the irradiated surface and therefore have to be replaced up to now after a short period of use. This is uneconomical because of the luxury production of high-precision mold cavities or large-volume molds. However, depending on the cost of producing the casting mold from, for example, polyacrylate, it is desirable to have at least 50, preferably at least 100, molding or radiation curing applications without causing a significant decrease in ultraviolet transmittance and cure rate.

The irradiation and molding unit of the invention is particularly useful for the production of moldings derived from photocurable polymers, in particular for the production of elastomer moldings, thermoset moldings, thermoplastic moldings or moldings of thermoplastic elastomers.

In addition, the irradiation and molding unit of the present invention should be as small as possible, which is required for the construction of many injection molding machines. The irradiation unit of the invention is thus fastened to a correspondingly provided mold clamping device in an injection molding machine. In this position, machine controlled filling, opening and closing of the mold cavity of the photocurable polymer composition is possible. In contrast, a relatively large-volume irradiation unit would require a complex injection molding machine with a correspondingly large mold clamping device, which would have to be produced separately, resulting in a considerable increase in costs.

From the prior art, casting molds with transparent windows are known, which can be considered for the molding and chemical crosslinking of photocurable polymers. US5401155 describes a metal mold with a light-transmissive window at the front end, placed perpendicular to the light source. US6627124 claims a two-part mold for producing a lens body, wherein one half of the mold is made of a transparent material. US5885514 teaches a method of forming and curing a seal on a seal plate having a transparent upper portion and a lower mold half. US2007/141739a1 discloses curing of silicone molding for encapsulation of light emitting diodes (LED's).

Since conventional light sources generate much heat, the production of larger moldings with currently available light sources from photocurable polymers often requires a compromise between the available uv light transmission, the transparent element and the permissible irradiation light power. In order to provide an inexpensive, easily manufactured and durable light transmitting element, i.e. a window, the transparent material has to fulfill a range of requirements for light entry. They must allow as completely as possible the transmission of the ultraviolet light of the desired wavelength without absorption losses. They should in particular be easy to shape if they are part of a shaping mold cavity. This means that the desired contour of the mould wall should be designed and worked in a simple manner. On the one hand, quartz glass is an ideal ultraviolet light transmitting material, which is further heat and scratch resistant, however, it is difficult to form by surface processing and is expensive. Although a transparent element made of quartz glass can certainly be used as a mold cavity wall or access window in a mold in a manner that reduces mechanical stress and reduces the risk of breakage, this application is subject to certain conditions. The brittleness of the quartz glass and the adhesion between the quartz glass and some photo-curable polymers, by means of which it can be adhesively connected, must be taken into account. This complicates the separation of the shaped articles after curing. Other salt water glasses or mineral glasses have similar advantages and disadvantages. However, these materials are well suited for simply designed mold cavities or injection channels, where smaller planar workpieces can be inserted as transparent windows.

Transparent thermoplastics are considered as an alternative, which are not sufficiently heat-resistant and have a too short lifetime under the previously known conditions of ultraviolet irradiation. The light source used during uv irradiation affects the transparent shaping in different ways. On the one hand, the very short wavelength range of the ultraviolet radiation leads to destruction of the polymer structure, and on the other hand, the heat generation in the light source for ultraviolet irradiation or the amount of radiation in the IR range in particular leads to an increase in the heat generation in the transparent molding. The heating of the transparent casting material by the uv light source causes it to expand, which negatively affects the geometric accuracy of the shapes produced therein. The problem of heat generation is certainly more severe as the present irradiation and shaping unit is constructed more compact.

On the other hand, many transparent thermoplastics can advantageously be easily processed into shaped elements for use in the molding channel or in the mold cavity or for the mold cavity (mold cavity) in comparison with quartz glass.

The aim that the inventors of the present patent application set themselves to solve is therefore to provide an irradiation and moulding unit that is as compact as possible, but nevertheless stable, which is suitable for use in a wide variety of injection moulding machines.

One method initially involves cooling of the transparent casting mold used by contacting the mold with a suitable liquid coolant, rather than in the field of ultraviolet light transmission from ultraviolet lamps, which has heretofore been considered detrimental to curing. By this form of cooling, the heat is naturally dissipated at the interface between the cooling medium and the transparent casting mould. By heat conduction inside the molding material, partial heat dissipation in the region of the transparent casting mold is also achieved, which is transmitted by ultraviolet light. However, the heat dissipation achieved is still considered to be insufficient, of course, especially in areas not in direct contact with the liquid coolant, especially in transparent areas. The inventors of the present patent application therefore sought the possibility of improving the cooling of transparent moldings, in particular of transparent moldings made of thermoplastic materials, in order to incorporate uv-curable resin compositions and thereby to increase their durability. A number of possibilities are considered, such as using a LED uv light source that generates less heat. However, they still typically produce too little radiant energy. Another possibility is seen in the cooling of the ultraviolet radiation source itself to reduce the thermal radiation, as shown in the example of US2002/0118541(a 1). However, heat dissipation here, in particular in the field of the transport of transparent casting molds, is still too little. Furthermore, the cooling of the ultraviolet radiation source is associated with an increased complexity of the technical installation and with an increased outlay.

Unexpectedly, the inventors of the present patent application have now found that an optimal and inexpensive cooling and a concomitant increase in the lifetime of the transparent moldings is possible. The positioning of the cooling device according to the invention results in less expansion of the casting mould and thus in increased accuracy of the shape and dimensional stability of the solidified shape. The illumination and shaping unit described subsequently can retain the ability to achieve a compact design. It comprises a liquid layer located between a transparent layer and one or more uv light sources. In which the coolant layer is not fixed to, nor part of, the uv light source, as schematically represented in figures 1 to 3. However, the cooled mold and the ultraviolet light source may optionally form a complete irradiation unit. The decisive factors are the position and location of the liquid layer. It is particularly unexpected that with this arrangement, the rate of crosslinking of the curable polymer composition in the transparent casting mold does not decrease significantly. Further, the cooling of the present transparent molded article can be achieved by heat transfer between the liquid layer and the transparent molded article or by selective absorption of heat and IR radiation (which is emitted from the ultraviolet radiation source without special technical measures on the ultraviolet radiation source). By using the irradiation and molding unit of the present invention, deformation, discoloration and clouding of the transparent molding element due to excessive irradiation are strongly suppressed. The present inventors have further succeeded in creating a device in which thermoplastic, ultraviolet-light transmissive elements, in particular, can be used without imposing their heat-resistant limiting burden, but while at the same time introducing high optical power each time into the polymer composition to be cured. The present transparent element may be suitable for photocurable polymers, depending on its compatibility (interaction with the photocurable polymer). Thus, by means of the device according to the invention, a significantly increased lifetime of the transparent shaped article can be achieved, resulting in an overall increased uv light output based on the energy and radiation power used. The device generally allows a processing method with a low tool temperature, which is advantageous for example for 2-part injection molding when composite parts are heat sensitive, or when injection of inserts made of plastic with a low heat resistance is to be performed. Further, the present invention allows the production and application of compact, complete casting molds for the preparation of photocured moldings, wherein the uv-transparent material of the present moldings, despite the superimposition of a liquid layer, is sufficiently transmissive to uv light and exhibits a long lifetime due to the liquid layer, while reducing the tendency to brittleness and clouding.

The present invention therefore provides an irradiation (and molding) unit (hereinafter simply referred to as an irradiation unit) for curing a photocurable polymer composition, comprising:

-one or more UV-light sources for irradiating at least one transparent layer, which is in contact with the photocurable polymeric compound and which is located between the UV-light source and the photocurable polymeric compound,

-at least one mould for receiving a photo-curable polymer compound, and

-at least one liquid layer which is located between the transparent layer and the one or more uv light sources and which is not permanently fixed to the uv light sources.

Herein, the term "not permanently fixed to the uv light source" means that the liquid layer is not part of the uv light source or its frame. Instead, the liquid layer is typically arranged separate from the uv light source or its frame. However, the present irradiation (and molding) unit may include the liquid layer and the ultraviolet light source fixedly arranged to each other. However, even in such cases, the ultraviolet light source is still a separate unit from the liquid layer, and is therefore prepared, sold, and used separately from the liquid layer.

Drawings

One embodiment of the irradiation and shaping unit of the present invention is schematically shown in fig. 1. In this embodiment of the illumination unit of the invention, the liquid layer is in direct contact with the transparent layer, the side of the liquid layer facing the ultraviolet light source being open, which means not being closed by the cladding layer. This particularly simple embodiment of the irradiation and shaping unit of the invention can be realized, for example, by passing a liquid film through a transparent layer. The thickness of the liquid layer can be varied by providing correspondingly high side walls in the area of the liquid layer.

Another embodiment of the invention is schematically illustrated in fig. 2. This embodiment differs from the embodiment shown in fig. 1 in that the liquid layer is conducted between the transparent layer and the transparent cover layer so to speak closed. In which a sealing element may be provided between the transparent layer and the transparent cover layer (not shown), which effectively prevents leakage of the liquid layer.

Another embodiment of the invention is schematically illustrated in fig. 3. This embodiment differs from the embodiment shown in fig. 1 in that the liquid layer is surrounded on both sides by transparent cover layers. In one embodiment shown herein, the transparent conversion layer on the side facing away from the ultraviolet light source is in direct, form-fitting contact with the transparent layer, which is in contact with the photoconductive polymer composition. This embodiment provides the following advantages: the element receiving the liquid layer does not need to be in tight contact with the transparent layer, which facilitates the exchange of the liquid layer and the cover, which together become a cooling channel. This has the following advantages: the liquid layer or the cold absorbing layer or the heat absorbing layer, respectively, may be provided as separate components which can be rapidly replaced during operation in accordance with the decreasing uv transmittance of the transparent cover layer. The transparent layer, which is typically present as part of the mold for receiving the photocurable polymer composition, is not affected and its durability is increased.

Fig. 4 shows a special embodiment of the embodiment of fig. 3, in which the liquid layer is surrounded by two transparent cover layers, which are separated from the transparent layer. This embodiment enables in a simple way also pushing the liquid layer as an exchangeable cooling plate between the transparent layer and the uv light source. The cooling effect in this embodiment is also sufficient in many cases, wherein the wrapped liquid layer is separated from the transparent layer. By passing a preferably cooled air flow between the encapsulated liquid layer and the transparent layer, an additional cooling effect can be achieved.

Fig. 5 shows a specific embodiment of the irradiation and shaping unit of the present invention, wherein the liquid layer is in direct contact with the uv-transparent layer. The liquid layer is encapsulated on the side facing the uv lamp. The liquid layer may be in direct contact with the ultraviolet-transparent layer on the side facing the ultraviolet-transparent layer, or a further cover layer may be provided between the liquid layer and the ultraviolet-transparent layer. In the latter case the element forming the liquid layer may be provided as a separate replaceable component. Even if only one cover layer is provided on the side facing the uv light source, it can be easily replaced if the transparency is reduced.

Fig. 6 shows a further embodiment of the irradiation and shaping unit of the invention, wherein the liquid layer is in direct contact with the uv-transparent layer. Wherein the liquid present in the liquid layer is recirculated. In the resulting cooling circuit, a heat exchanger (not shown) is preferably incorporated. Also in this embodiment, the element comprising the liquid layer may be formed as an alternative component.

Fig. 7 shows the temperature change in the transparent layer formed as part of the mold receiving the photocurable polymer composition derived from Polymethylmethacrylate (PMMA) depending on the number of irradiation cycles of the embodiment of the present invention corresponding to the embodiment shown in fig. 3. As the liquid layer, a mobile aqueous layer at about 20 ℃ was used. The liquid layer is encapsulated, in direct contact with the PMMA layer. As can be seen in fig. 7, the application of the liquid layer according to the invention results in a significant reduction in the temperature in the PMMA shaping layer, so that it has a significantly reduced tendency to yellow, no deformation and its lifetime with respect to the transmission of uv light is significantly extended.

According to prior knowledge, the liquid layer for the irradiation unit according to the invention substantially fulfils the following functions.

First, it cools the transparent layer by absorbing and dissipating heat from the transparent molding layer, especially in the area facing the uv light source or the area transmitted by the uv light. On the other hand, it absorbs heat or IR radiation generated in the uv light source, thereby preventing the resulting heating of the transparent molding layer and its deformation. Furthermore, the liquid layer may be designed to absorb a portion of the shorter wavelength portion of the ultraviolet light, which may also reduce the lifetime of the transparent shaping layer. Surprisingly, with this relatively simple construction, particularly effective cooling of the transparent molding layer and the resulting increase in the service life are achieved, as well as little deformation of the transparent molding layer, with a corresponding increase in the accuracy of the shape of the cured molded article produced.

Detailed Description

In a preferred embodiment of the invention, the irradiation and shaping unit is characterized in that the liquid layer has a thickness of between 0.01mm and 50mm, preferably between 1 and 10 mm. The above thicknesses actually comprise only the thickness of the liquid layer and do not comprise the thickness of any optionally surrounding cover layer. If the thickness of the liquid layer is too low, the filtering effect (temperature and radiation) is in some cases insufficient. A thickness above 50mm is generally not useful because it does not provide an additional contribution to cooling.

In a further preferred embodiment of the invention, the irradiation unit is characterized in that the thickness of the liquid layer is of such a size that it absorbs at least 70%, preferably at least 80%, more preferably at least 90% of the portion of the total radiation of the uv light source in the range of more than 700 nm.

In a further preferred embodiment of the invention, the illumination unit is characterized in that the liquid layer is in contact with the transparent layer and with the uv light source. Such an embodiment may for example be realized in that the liquid layer is located on or flows through the transparent layer by using suitable side walls, with the uv-light source being immersed in or contacting the liquid layer.

However, it is more preferred to provide a separation between the one or more uv light sources and the liquid layer in the range of at least 1mm, more preferably in the range of > 10mm, even more preferably in the range of > 30 mm. Preferably, the maximum value of the spacing is 150mm, more preferably at most 100 mm. This results in preferred respective ranges of, for example, 1 to 150mm and 10 to 100 mm.

In a preferred embodiment, the irradiation unit has a method of exchanging liquid in a liquid layer. These methods ensure that the liquid is recirculated in the liquid layer. This can preferably be achieved in a circuit with an additional heat exchanger. Preferably, the mass flow rate in the liquid layer is at least 0.1g/(min cm)²) More preferably 0.5 to 50 g/(min. cm)²) Still more preferably 5 to 10 g/(min. cm)²)。

In a preferred embodiment of the invention, the liquid layer is in direct contact with a transparent layer, which is in contact with the photocurable polymer composition by transmission of ultraviolet light. In this way, naturally more heat is dissipated from the transparent layer, as in the embodiment where there is a cover layer in between the liquid layer and the transparent layer. However, embodiments of the illumination unit, wherein the liquid layer is located between and in contact with the transparent layer and the transparent cover layer, are in many cases sufficient for heat dissipation. This embodiment generally makes the exchange of the elements of the liquid-conducting layer easy.

In a further preferred embodiment of the illumination unit according to the invention, the liquid layer is located between two transparent cover layers, which are located between the uv-light source and the transparent layer. Here, as described above, the transparent cover layer facing the transparent layer may be in contact with or separated from the transparent layer. This embodiment still has the following advantages: the component comprising the liquid layer, consisting of the two cover layers and the intermediate liquid layer and optionally the peripheral devices (wiring, heat exchangers, etc.), as formed in the form of a cooling plate, can be simply taken out of the beam path of the ultraviolet light and can be exchanged for another corresponding new component without major maintenance work. This is often necessary when the transparency of the cover layer, in particular towards the uv light source, becomes so poor that the curing rate becomes unacceptable.

As already mentioned, the embodiment in which the cover layer facing away from the uv light source is in contact with the transparent layer has the advantage that heat dissipation in the transparent layer is better. In a preferred embodiment, the liquid layer is in contact with a heat exchanger to dissipate heat generated therein. Preferably, the liquid of the liquid layer absorbs infrared radiation. At the same time, however, it must be transparent to ultraviolet radiation, since this results in curing of the photocurable polymer composition. In a preferred embodiment, the liquid of the liquid layer is selected from the group consisting of: water, aliphatic alcohols, hydrocarbons, ionic liquids and salts and mixtures thereof. The liquid of the liquid layer may also include one or more IR absorbing additives. These IR absorbing additives include, for example, soluble or colloidal IR absorbing additives which however absorb as little uv light as possible, for example organic compounds having the respective absorption spectrum or suitable colloidal oxides or hydroxides of metals such as a1, B, Ce, In, Sn or semimetals such as Si, Ge, which may optionally be modified with organic groups.

In a further embodiment of the illumination unit, it is characterized in that an additional non-fluid based IR radiation filter is placed between the ultraviolet light source and the transparent layer. Such IR radiation filters include, for example, wavelength sensitive filters or dichroic mirror elements. In the irradiation unit of the invention at the uv light source comprising any filter element, the fraction of the total radiation in the range > 700nm is less than 15%, in the range < 300nm is less than 15%.

In a further embodiment of the illumination unit according to the invention, it is characterized in that it comprises one or more elements which guide and/or reflect light.

In a further embodiment of the irradiation unit of the invention, it is characterized in that it comprises one or more injection channels for photocurable polymer compounds.

The uv light source used in the present invention is preferably selected from: ultraviolet fluorescent lamps, high-pressure mercury vapor lamps, ultraviolet arc lamps, metal halide lamps, xenon lamps, flash lamps, undoped or Fe-or gallium-doped mercury lamps, and black light lamps. Mercury lamps doped with Fe or gallium are particularly preferred.

In the irradiation unit of the invention, the distance between the liquid layer and the ultraviolet light source is fixed or variable. A variable distance may be advantageous to provide the possibility of inserting additional elements, such as filters or screens, into the light path when desired.

The irradiation unit of the invention is preferably designed to consist of several sub-components forming an assembly of irradiation units. Typically, it includes the following subcomponents: an ultraviolet radiation source component, a component for receiving the liquid layer, and a shaping component. The combination of these components may be provided in a fixed or removable manner, the latter embodiment being preferred as this allows for replacement of the individual components. In a further embodiment of the irradiation unit, it comprises one or more injection channels for a photocurable polymer composition, which affect the feeding of the casting mould in which the curing takes place.

The irradiation unit of the present invention has a transparent layer in contact with the photocurable polymer composition through which ultraviolet light passes through the photocurable polymer composition and effects curing thereof. Preferably, the transparent layer may be a portion of a mold for receiving a photo-curable polymer in which curing occurs. However, it is also possible to provide a transparent layer in the injection channel. Such injection channels may, for example, be constructed like imaging exposure spots. In this embodiment, naturally no curing takes place in the injection channel, i.e. the irradiated polymer composition, which is still flowable, is introduced into the casting mould, where it is cured. Generally, this is the case when the irradiation time is less than the so-called gel time (see example EP1817372B 1). Also in this embodiment, the cooling and thus the prolonging of the lifetime of the transparent areas, which are substantially made of thermoplastic polymer, in particular PMMA, is achieved by the irradiation unit according to the invention, while the temperature of the irradiated photocurable polymer composition, and thus of the solidified casting mould, is reduced. This in turn leads to a higher accuracy of the shape in the final cure in the curing mold. In the irradiation unit according to the present invention, the transparent layer in contact with the photocurable polymer composition is preferably composed of a thermoplastic polymer material. Such polymeric materials preferably include polymethacrylates, which will be described in more detail below. In a preferred embodiment, the entire mold for receiving the photocurable polymer composition is composed of a thermoplastic polymer material.

However, it is also possible according to the invention for the casting mould for receiving the photocurable polymer composition to comprise non-transparent areas, which are formed, for example, of metal. In the case where radiation occurs in the region of the injection channel, the entire mold for receiving the photocurable polymer composition (sometimes referred to as a curing mold) may be made of a non-transparent material.

In a further embodiment of the invention, the illumination unit may have a plurality of uv light sources.

The UV light source used in accordance with the present invention preferably has at least 0.1mW/cm²Of (2) is performed.

The irradiation unit of the present invention may be used for continuous or batch production of cured polymer molded articles, or for production of articles having a layer of cured polymer. In the latter case, the photocurable polymer composition is contacted with the coated substance.

The irradiation unit of the present invention is preferably used for curing a photocurable silicone composition, which will be described in more detail below.

According to the invention, a sub-assembly of the illumination unit is also required which does not comprise a uv light source. By means of this sub-assembly, the irradiation unit of the invention can be formed in a simple manner by adding a commercially available uv light source.

Accordingly, the present invention also includes a mold assembly for curing a photocurable polymer composition comprising:

-at least one casting mould for receiving a photocurable polymer composition

-at least one transparent layer in contact with the photocurable polymer composition, which is transparent to violet light irradiation, and

-at least one liquid layer arranged in such a way that it can be irradiated by irradiation of the transparent layer.

To the extent that the molding unit is devoid of an ultraviolet light source, the explanation of the irradiation and molding unit according to the invention applies accordingly. By means of the shaping unit, the irradiation and shaping unit of the invention can be formed by adding one or more uv light sources.

The invention further relates to a method for producing a cured polymer molding or an article covered with a cured polymer, wherein one or more photocurable polymer compositions are cured by means of the irradiation unit according to the invention. The method preferably comprises the steps of:

a) optionally, the components of the irradiation unit are combined,

b) optionally inserting one or more articles to be coated into a mold for receiving the photocurable polymer composition,

c) introducing one or more photocurable polymer compositions, optionally through one or more injection channels,

d) irradiating the photocurable polymer composition through the transparent layer in the region of the injection passage and/or the mold for receiving the photocurable polymer composition,

e) the cured polymer molding or polymer covering is removed continuously or in batches.

In a preferred embodiment of the method, the following steps are additionally included:

a) the range of effective wavelengths for activating cure is determined,

b) the uv light source with the largest radiation is selected within the effective wavelength range.

An improvement in the absorption properties provided by the liquid layer can be achieved. The effective wavelength for curing the photocurable polymer composition preferably ranges from 345 to 385nm (absolute or local maxima of the wavelength range).

The invention further provides the use of an irradiation unit for the preparation of a polymer moulding or polymer covering.

By means of the irradiation unit according to the invention, in principle any photocurable composition can be cured, for example various acrylates, acrylate derivatives, aliphatic or aromatic epoxides as disclosed in EP0826431a1, further vinyloxo derivatives as disclosed in EP548826a2 or EP1265942a2, thiol-substituted aliphatic or aromatic monomers or oligomers, unsaturated polyesters, diallyl-substituted ammonium compounds, including mixtures thereof with each other or with clear filters and silicone rubber compositions, etc. Further photocurable polymer, oligomer and/or monomer compositions (a) which may optionally be used in combination with components (a1) and (a2) are, for example, various acrylates, acrylate derivatives, aliphatic or aromatic epoxides as disclosed in EP0826431a1, further vinyloxo derivatives, thiol-substituted aliphatic or aromatic monomers or oligomers, unsaturated polyesters, diallyl-substituted ammonium compounds as disclosed in EP548826a2 or EP1265942a2, including mixtures thereof with one another.

Photocurable polymer compositions, such as photocurable flowable polymer, oligomer and/or monomer compositions, are preferred, such as photocurable polymer compositions comprising:

(A) one or more polymers, oligomers and/or monomers having one or more photoreactive groups,

(B) one or more catalysts selected from the group consisting of,

(C) optionally, one or more sensitizers,

(D) optionally, one or more inhibitors,

(E) optionally, one or more components capable of reacting with component (A),

(F) optionally, one or more filters.

In particular, component (a) may be selected from flowable polysiloxanes having photoreactive or photocurable functional groups.

In a preferred embodiment, component (a) is selected from polysiloxanes (a1) comprising siloxy units having the formula:

R_aR¹ _bSiO_(4-a-b)/2 (1)，

wherein the groups R, which may be the same or different, are substituted or unsubstituted monovalent hydrocarbon groups which do not have photoreactive groups; radical R¹Are identical or different and are photoreactiveA group; and a and b are integers from 0 to 3, represent subscripts to the respective siloxy unit (M, D, T or Q) and are therefore

M：a+b＝3，

D：a+b＝2，

T：a+b＝1，

Q：a+b＝0，

Which on average has less than 10 mol% of branching units (T or Q), preferably has a viscosity of from 0.01 to 100000 Pa.s at 25 ℃, where the preferred molar ratio is R¹2/10000 to 2/10, hence 2 x 10^-4To 0.2, and/or

(A2) Photoreactive polysiloxanes having the formula

R_aR¹ _bSiO_(4-a-b)/2 (1’)，

Wherein a and b are as defined above, but which comprise on average more than 10 mol% of branching units (T, Q), i.e.are resin-like, which are solid or liquid at room temperature (25 ℃). Preferred is a photoreactive polysiloxane (A2) having mainly M, T and Q units, wherein the molar ratio M/(Q + T) is 0.4 to 4.0, and the molar ratio R is¹0.01 to 0.50% of/Si.

Furthermore, a mixture of a plurality of components (a1), a plurality of components (a2) and a mixture of one or more components (a1) and one or more components (a2) can be used as component (a).

In the polysiloxane of formula (1) or (1'), the monovalent hydrocarbon group represented by R is preferably a hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms, such as an alkyl group selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, octyl and decyl, a cycloalkyl moiety such as cyclopentyl and cyclohexyl, an aryl moiety such as phenyl and tolyl, and an aralkyl group such as benzyl and phenethyl.

In the polysiloxanes of formula (1) or (1'), alkoxy groups can be present to some extent, for example up to 20 mol-%, preferably up to 10 mol-%, more preferably up to 5 mol-%, based on the number of silicon atoms, of the radicals R, for example alkoxy groups having from 1 to 8 carbon atoms, in particular from 1 to 4 carbon atoms, such as methoxy, ethoxy, propoxy and butoxy.

R is not limited to unsaturated monovalent hydrocarbons (and alkoxy groups, if applicable), but includes substituted forms of these groups in which some or all of the hydrogen atoms bonded to carbon atoms are substituted with halogen atoms, cyano groups, alkoxy groups, and the like, for example, substituted hydrocarbon groups and substituted alkoxy groups such as chloromethyl, 3, 3, 3-trifluoropropyl, and cyanoethyl groups.

Preferred at the silicon are methyl, phenyl and 3, 3, 3-trifluoropropyl.

R¹Is a photoreactive group selected from alkenyl groups, methacryloyl-containing groups, alkenylalkoxy-containing groups, such as vinylalkoxy-containing groups, cyclohexenylethyl-containing groups, limonene-based groups (limonyl), dicyclopentadiene, norbornenyl groups (norbomenyl) and epoxyalkyl-containing groups.

The (meth) acryloyl-containing group includes, for example, (meth) acryloylalkyl groups in which the alkyl moiety has 2 to 14 carbon atoms, such as γ -allyloxypropyl and γ -methacryloyloxypropyl.

The vinylalkoxy group includes, for example, vinylalkoxy groups wherein the alkyl portion has 3 to 8 carbon atoms, such as vinylpropoxy.

Epoxy-containing groups include, for example, glycidyloxyalkyl groups in which the alkyl moiety has from 3 to 14 carbon atoms, such as gamma-glycidyloxypropyl and (3, 4-epoxycyclohexyl) alkyl.

From R¹At least 2, preferably 2 to about 10 photoreactive groups should be present per molecule. From R¹Indicating that polysiloxanes with less than two photoreactive groups do not cure completely. It should be noted that R¹May be at the terminal of the molecular chainOr with the central portion attached to a silicon atom.

The photoreactive group R is mainly based on its reaction mechanism¹Can be assigned to 3 groups, such as activatable groups on the groups, activatable groups on cationic groups and those groups capable of hydrosilylation.

Preferred at the silicon are methacryloxypropyl, mercaptopropyl, vinylalkoxy, vinyl, and gamma-glycidyloxypropyl residues.

Branched polysiloxanes (A2) which may preferably optionally be used are silicone resins, which preferably have an increased number of reactive groups R¹And thus contribute to an increased crosslink density if used in the respective amounts. This component (A2) increases strength, tear strength and hardness. A similar effect can be achieved by component (A1) if it has a high concentration of 1-50 mol-% of reactive groups R¹(based on all silicon atoms) and, if added in an amount of 0.2 to 90wt. -%, preferably 1 to 40wt. -%, based on the total amount of component (a1), for example in the further component (a1), preferably only 0.01 to 0.9 mol-% of reactive groups.

By means of these mixtures, the use of reinforcing fillers can be avoided completely or partially, thereby maintaining the transparency of the composition at a high level. In a process for producing a molded article from a photocurable polymer, the transparency of the photocurable polymer composition promotes the transmission of light-activated ultraviolet radiation into a mold cavity.

The silicone resin (A2) is synthesized, for example, by mixing vinyldimethylmethoxysilane and tetramethoxysilane in the desired molar ratio, hydrolyzing, condensing to a polymer and optionally equilibrating. In other syntheses, vinyltrimethoxysilane and tetramethoxysilane are co-hydrolyzed in the desired ratio to introduce trifunctional T or Q groups. Instead of alkoxysilanes, chlorosilanes or mixtures of chlorosilanes and alkoxysilanes can be used accordingly. For example, sodium silicate may also be used instead of tetramethoxysilane. Similarly, the use of hexaorganodis-iloxanes (hexaorganodis-ilxanes) is possible, for example 1, 3-divinyl-1, 1, 3, 3-tetramethyldisiloxane, which can be added to the hydrolysate and condensed or equilibrated in the polymerization.

If the friable nature (durometer) of the cured composition is desired or accepted, then up to 90wt. -% (based on the total amount of components (a1) and (a 2)) of component (a2) may be used.

Component (B) is selected from one or more catalysts that can affect the curing of the photoreactive groups in the component. Depending on the nature of the photoreactive group or curing mechanism, the catalyst includes, for example:

for radical curing, i.e. R¹Alkenyl, methacryloyl, alkenyl such as vinyl, allyl, hexenyl, cyclohexenylethyl, limonene, functional polysiloxanes (A) which are:

photoinitiators, e.g. acylphosphine oxides, acetophenones, propiophenones, benzophenones, xanthones (xanthhols), fluorenes, benzaldehydes, anthraquinones, triphenylamines, carbazoles, 3-methylacetophenones, 4-methylacetophenones, 3-pentylacetophenones, 4-methoxyacetophenones, 3-bromoacetophenones, 4-allylacetophenones, p-diacetylbenzenes, 3-methoxybenzophenones, 4-methylbenzophenones, 4-chlorobenzophenones, 4-di-methoxybenzophenones, 4-chloro-4-phenylmethylbenzophenones, 3-chlorooxanthrone, 3, 9-dichlorooxanthrone, 3-chloro-8-nonyloxanthrone, benzoins, benzoin ethers such as benzoin methyl ether and benzoin butyl ether, bis (4-xylenyl) methanones, Benzyl methoxy ketal and 2-chlorothioxanthone, light activated peroxides such as perbenzoates of the general formula:

A-O-O-CO-C₆H₅-B

wherein A is alkyl or aryl and B is hydrogen, alkyl, halogen, nitrogen, amino or amide, such as tert-butyl perbenzoate and para-substituted derivatives thereof, such as tert-butyl peroxy-p-nitrobenzoate, tert-butyl peroxy-p-methoxybenzoate, tert-butyl peroxy-p-methylbenzoate and tert-butyl peroxy-p-chlorobenzoate, azo compounds, such as azodicarbonyl ester, azodicarboxylic acid amide or azobisisobutyronitrile.

For cationic curing, for example, for epoxy-functional or alkenyl ether-functional, i.e. ethyleneoxy, propyleneoxy-functional polydiorganosiloxanes, these are:

as described in US4576999Salt:

R⁵ ₂I⁺MX_n ^-

R⁵ ₃S⁺MX_n ^-

R⁵ ₃S_e ⁺MX_n ^-

R⁵ ₄P⁺MX_n ^-

R⁵ ₄N⁺MX_n ^-

wherein R is⁵Which may be identical or different, are selected from organic radicals having up to 30 carbon atoms, such as aromatic hydrocarbon residues,the anion being selected from the group MXn, wherein MXn is, for example, BF₄ ^-、PF₆ ^-、AsF₆ ^-、SbF₆ ^-、SbCl₆ ^-、HSO₄ ^-、ClO₄ ^-And the like. More and moreCatalysts are known from EP703236 and US5866261, for example B (C)₆F₅)₄ ^-And (3) salt. In addition, the first and second substrates are,the catalyst comprises a diazonium salt, such as 4-morpholino-2, 5-dimethoxy-phenyldiazofluoroborate.

For curing by hydrosilylation (i.e. with an alkenyl-functional polydiorganosiloxane), the catalyst (B) is selected from the group consisting of: photoactivatable hydrosilylation catalysts, especially metal compounds such as Ag, Co, Fe, Ir, Os, Ni, Pd, Pt, Rh and Ru.

Examples of photoactivatable platinum catalysts (B) are (η -diolefins) (δ -aryl) -platinum complexes, as disclosed for example in US4530879A (wherein "COD" refers to cyclooctadiene, "COT" refers to cyclooctatetraene and "NBD" refers to norbornadiene):

(1, 5-COD) Diphenylplatinum

(1, 3, 5, 7-COT) Diphenylplatinum

(2, 5-NBD) Diphenylplatinum

(3a, 4, 7, 7 a-tetrahydro-4, 7-methanolic indene) diphenylplatinum

(1, 5-COD) -bis (4-methylphenyl) platinum

(1, 5-COD) -bis (2-methylphenyl) platinum

(1, 5-COD) -bis (2-methoxyphenyl) platinum

(1, 5-COD) -bis (3-methoxyphenyl) platinum

(1, 5-COD) -bis (4-methoxyphenyl) platinum

(1, 5-COD) -bis (4-methylthiophenyl) platinum

(1, 5-COD) -bis (3-chlorophenyl) platinum

(1, 5-COD) -bis (4-fluorophenyl) platinum

(1, 5-COD) -bis (bis 2, 4-fluorophenyl) platinum

(1, 5-COD) -bis (4-bromophenyl) platinum

(1, 5-COD) -bis (4-trifluoromethylphenyl) platinum

(1, 5-COD) -bis (bis-3, 5-trifluoromethylphenyl) platinum

(1, 5-COD) -bis (3-trifluoromethylphenyl) platinum

(1, 5-COD) -bis (2, 4-bis (trifluoromethyl) phenyl) platinum

(1, 5-COD) -bis (4-dimethylaminophenyl) platinum

(1, 5-COD) -bis (4-acetylphenyl) platinum

(1, 5-COD) -bis (trimethylsilyloxyphenyl) platinum

(1, 5-COD) -bis (trimethylsilylphenyl) platinum

(1, 5-COD) -bis (pentafluorophenyl) platinum

(1, 5-COD) -bis (4-benzylphenyl) platinum

(1, 5-COD) -bis (1-naphthalene) platinum

(1, 5-COD) -naphthylphenylplatinum

(1, 5-COD) -bis (2H-chromen-2-yl) platinum

(1, 5-COD) -bis (xanthene-1-phenyl) platinum

(1, 3, 5-cycloheptatriene) diphenylplatinum

(1-chloro-1, 5-COD) diphenylplatinum

(1, 5-dichloro-1, 5-COD) Diphenylplatinum

(1-fluoro-1, 3, 5, 7-COT) diphenylplatinum

(1, 2, 4, 7-tetramethyl-1, 3, 5, 7-COT) -bis (4-methylphenyl) platinum

(7-chloro-2, 5-NBD) diphenylplatinum

(1, 3-cyclohexadiene) diphenylplatinum

(1, 4-cyclohexadiene) diphenylplatinum

(2, 4-hexadiene) diphenylplatinum

(2, 5-pentadiene) Diphenylplatinum

(1, 3-dodecadiene) diphenylplatinum

Two eta²-2- (2-propenyl) phenyl]Platinum (II)

Two eta²-2- (vinylphenyl) platinum

Two eta²-2- (cyclohexen-1-ylmethyl) phenyl]And platinum.

Further photoactivatable catalysts include (eta-diolefin) (delta-alkyl) -platinum complexes, e.g.

(1, 5-COD) Pt (methyl)₂

(1, 5-COD) Pt (benzyl)₂

(1, 5-COD) Pt (hexyl)₂

Particularly preferred catalysts in view of reactivity and curing speed are:

(η⁵-cyclopentadienyl) -trialkyl-platinum-complexing compounds, e.g. (Cp ═ cyclopentadienyl)

(Cp) trimethyl platinum

(Cp) Ethyl dimethyl platinum

(Cp) triethylplatinum

(Cp) triallyl platinum

(Cp) Tripentylplatinic acid

(Cp) Trihexylplatinum

(methyl-Cp) trimethylplatinum

(trimethylsilyl-Cp) trimethylplatinum

(Phenyldimethylsilyl-Cp) trimethylplatinum

(Cp) acetyldimethylplatinum

(Cp) Diethylmethylplatinum

(Cp) Triisopropylplatinum

(Cp) tris (2-butyl) platinum

(Cp) triallyl platinum

(Cp) Trinonyl platinum

(Cp) Tridodecyl platinum

(Cp) tricyclopentylplatinum

(Cp) Tricyclohexylplatinum

(chloro-Cp) trimethylplatinum

(fluoro-Cp) trimethylplatinum

(Cp) dimethyl benzyl platinum

(Triethylsilyl-Cp) trimethylplatinum

(Dimethylphenylsilyl-Cp) trimethylplatinum

(Methylbiphenylsilyl-Cp) trimethylplatinum

(Triphenylsilyl-Cp) trihexylplatinum

[1, 3-bis (trimethylsilyl) -Cp ] trimethylplatinum

(Dimethyloctadecylsilyl-Cp) trimethylplatinum

1, 3-bis [ (Cp) trimethylplatinum ] tetramethyldisiloxane

1, 3-bis [ (Cp) trimethylplatinum ] dimethyldiphenyldisiloxane

1, 3-bis [ (Cp) dimethylphenylplatinum ] tetramethyldisiloxane

1, 3, 5-tris [ (Cp) trimethylplatinum ] pentamethyltrisiloxane

1, 3, 5, 7-tetrakis [ (Cp) trimethylplatinum ] heptamethyltetrasiloxane

(methoxy-Cp) trimethylplatinum

(ethoxymethyl-Cp) ethyldimethylplatinum

(Methoxycarbonyl-Cp) trimethylplatinum

(1, 3-dimethyl-Cp) trimethylplatinum

(methyl-Cp) triisopropylplatinum

(1, 3-diacetyl-Cp) diethylmethyl platinum

(1, 2, 3, 4, 5-pentachloro-Cp) trimethyl platinum

(phenyl-Cp) trimethylplatinum

(Cp) acetyldimethylplatinum

(Cp) propionyl dimethylplatinum

(Cp) Acryloyldimethylplatinum

(Cp) bis (methacryloyl) ethylplatinum

(Cp) dodecaacyldimethylplatinum and

trimethyl platinum-cyclopentadienyl-terminated polysiloxanes.

Most preferred are cyclopentadienyl-tri-alkyl-platinum-compounds, cyclopentadienyl-tri- (triorganosilyl) alkyl-platinum compounds, especially alkylcyclopentadienyl-trimethyl-platinum, e.g. methylcyclopentadienyl-trimethyl-platinum, optionally substituted by alkyl or trialkylsilyl groups. Further, Pd-acetylacetone or Pd-3-methylacetoacetone, for example, may be selected.

Further, it is possible to use: pt-diketones, such as Pt-acetylacetone (see US2003/0199603, US6150546, US6127446(GE)), Pt-trialkyl-diketones of WO95/25735, Ru complexes of US2004/0105934, with all catalysts disclosed in the aforementioned patent documents, are included in the disclosure of the present invention.

The content of component (B) used in the hydrosilylation reaction curing system is advantageously about 0.1 to 1000ppm, preferably 0.5 to 500ppm, more preferably 1 to 100ppm, still more preferably 2 to 50ppm, even more preferably 2 to 20ppm, calculated as metal, and based on the weight of component (A).

The crosslinking rate is determined, inter alia, by the catalyst compound selected, its amount and also the amount and type of additional component (D), i.e.inhibitor of the hydrosilylation reaction, optionally used.

For the photo-activatable catalyst (B), the catalyst concentration for the radical curable composition is 0.01 to 5 parts by weight, more preferably 0.01 to 0.5 parts by weight, per 100 parts by weight of component (a).

For cationically curable compositions, the amount of the photoactivatable catalyst (B) is selected from up to 5 parts by weight per 100 parts by weight of component (a). Preferably, catalyst (B) is added in a minimum amount to affect curing of the composition.

Less than 0.01 parts of the photoactivatable catalyst (B) in the radically or cationically curable composition is often insufficient to cure the silicone rubber composition. With more than 5 parts of the photoinitiator (B), light transmittance can be reduced so that the curing reaction can be continued for too long.

Photocurable compositions based on component (A) comprise polymers, oligomers and/or monomers, having one or more photoreactive groups, such as, in particular, flowable silicone rubber compositions comprising, for example, (A1) and/or (A2), optionally comprising one or more sensitizers (C). The sensitizer (C) is a compound capable of absorbing electromagnetic radiation in the visible region of the spectrum (i.e., 400nm to 800nm), this energy being transferred to the catalyst. They should advantageously have a triplet energy of at least 130 kJ/mol. Representative examples include aromatic ketones such as polycyclic aromatic sensitizers, e.g., anthracene, 9-vinylanthracene, 9, 10-dimethylanthracene, 9, 10-dichloroanthracene, 9, 10-dibromoanthracene, 9, 10-diethylanthracene, 9, 10-diethoxyanthracene, 2-ethyl-9, 10-dimethylanthracene, tetracene, pentacene, benzo [ a ] anthracene, 7, 12-dimethylbenzo [ a ] anthracene, azulene, e.g., 2-chlorothioxanthone, 2-isopropylthioxanthone, thioxanthone, anthraquinone, benzophenone, 1-chloroanthrone, dianthrone, and the like.

In the case of silicone rubber compositions which can be cured by a hydrosilylation reaction, comprising, for example, components (a1) and/or (a2), they optionally comprise one or more inhibitors (D) which influence the rate of the hydrosilylation reaction. Thus, the rate of crosslinking can be affected, and it is believed that, for example, hydrosilylation reactions do not prematurely begin to cure the silicone rubber, especially outside the mold cavity. Examples of known inhibitors include, for example: ethylenically unsaturated amides (US 4337332); acetylenic compounds (US3445420, US4347346), isocyanates (US 3882083); unsaturated siloxanes (US 3989667); unsaturated diesters (US4256870, US4476166 and US4562096), hydroperoxides (US4061609), ketones (US 3418731); sulfoxides, amines, phosphines, phosphites, nitriles (US3344111), diaziridines (US4043977), acetylenic alcohols such as ethynylcyclohexanol and 3-methylbutanol as described for example in US3445420, and diallyl maleate and dimethyl maleate and fumarate esters of unsaturated carboxylic esters (US4256870) and US4562096 and US4774111, for example diethyl fumarate, diallyl fumarate and di- (methoxyisopropyl) maleate, furthermore vinylsiloxanes such as 1, 3-divinyltetramethyldisiloxane or tetravinyltetramethylcyclotetrasiloxane.

The amount of inhibitor component is chosen such that the desired curing time can be adjusted under the selected process conditions, in particular in a suitable manner (i.e. time and temperature) in coordination with the catalyst (B) and the other components. The amount of inhibitor component is preferably from 0.0001 to 2% by weight (based on the amount of component (a)) of one or more inhibitors.

Optionally, the photocurable, flowable polymer, oligomer and/or monomer composition, such as a photocurable silicone rubber composition, includes one or more components (E) capable of reacting with component (a) to form a chemical bond with (a) in a polymerization, oligomerization, or crosslinking reaction.

In the case of the alkenyl-functional polyorganosiloxane (A) curable by hydrosilylation, the photocurable silicone rubber composition must have SiH-functional polyorganosiloxane as component (E). Preferably, in this case, at least one of the components (a) or (E) has a functionality of more than 2, so that a crosslinked structure can be formed. As SiH-functional organopolysiloxanes (E), for example SiH-functional polyorganohydrogensiloxanes, selected from the group of linear, cyclic or branched SiH-containing polyorganosiloxanes, e.g.

HR₂SiO(R₂SiO)_z(RHSiO)_pSiR₂H (2a)

HMe₂SiO(Me₂SiO)_z(MeHSiO)_pSiMe₂H (2b)

Me₃SiO(Me₂SiO)_z(MeHSiO)_pSiMe₃ (2c)

Me₃SiO(MeHSiO)_pSiMe₃ (2d)

{[R₂R³SiO_1/2]_0-3[R³SiO_3/2][R⁴O)_n}_m (2e)

{[SiO_4/2}][R²O_1/2]_n[R₂R³SiO_1/2]_0，01-10[R³SiO_3/2]_0-50[RR³SiO_2/2]_0-1000}_m(2f)

Wherein

z is 0 to 1000

p is 0 to 100

z + p is 1 to 1000

n is 0,001 to 4

m is 1 to 1000, and m is a linear or branched,

wherein R is²O_1/2Is an alkoxy residue at the silicon site of the molecule,

R³hydrogen or R, as defined above, preferably C₁-C₁₂Alkyl radical, C₁-C₁₂-alkoxy (C)₁-C₁₂) Alkyl radical, C₅-C₃₀-cycloalkyl or C₆-C₃₀-aryl, C₁-C₁₂Alkyl (C)₆-C₁₀) -aryl, wherein at least two residues R³Each of which is hydrogen, optionally substituted with one or more F atoms and/or having one or more O-groups.

In this system, curable by hydrosilylation, it is preferred that the ratio of component (E) to component (A) is such that there is a molar ratio of Si-H to Si-alkenyl units of from about 0.5 to 20: 1, preferably from 1 to 3: 1. The preferred amount of polyorganohydrogensiloxane used as component (E) is from 0.1 to 200 parts by weight, based on 100 parts by weight of component (A). Many properties such as rubber mechanical properties, crosslinking rate, stability and thickness can be influenced by the molar ratio of SiH to Si-alkenyl units.

The polyorganohydrogensiloxanes (E) may be linear, branched, cyclic. The polyorganohydrogensiloxane has, for example, a viscosity of about 5 to 1000 mPas at 25 ℃.

In the case of radical-curing silicone resin compositions in particular in which alkenyl-or methacryloyl-functional polydiorganosiloxanes (a) are used, it is possible to use, as crosslinking agents (E), optionally polyfunctional mercapto-containing compounds, such as the mercapto-containing compounds described in EP832936a1, in particular mercaptosilanes or mercaptopolysiloxanes having from 2 to 50 mercapto groups. In general, even a monomer, oligomer or polymer having a polyfunctional group-crosslinkable group may be used without limitation, for example, a polyalkenyl compound such as glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate or pentaerythritol tetra (meth) acrylate.

The photocurable compositions used according to the invention may optionally comprise as component (F) one or more fillers, for example in the case of siliconesThe same is often used in photocurable compositions of gum rubbers, provided that they are sufficiently transmissive to light-activating ultraviolet light. Therefore, special reinforcing fillers without light-scattering aggregates are preferred, whereby those smaller than 200nm are preferred. Reinforcing fillers (F) satisfying this condition are, for example, selected from the group comprising: organic and inorganic resins that are solid at 25 ℃, such as silsesquioxanes, metal oxide or metal oxide hydroxide colloids, for example, metal oxide or metal oxide hydroxide colloids of A1, B, Ce, Ga, In, Si, Zn, Ti, Sn, Sb. It is preferable that the average primary particle diameter is in the range of 5 to 20nm and the specific surface area according to BET is 150 to 400m²Silicate or silica gel in g, prepared by various methods such as flame hydrolysis, precipitation, sol-gel methods, etc. Examples include smoke silicates such as aerosil (Evonik), HDK (Wacker), Cab-O-Sil (Cabot).

The term filler (F) includes fillers with hydrophobicizing or dispersing agents or processing aids bound to the surface, which influence the interaction of the filler with the polymer, such as thickening effect, preferably weaken the interaction of the filler with the polymer, such as thickening effect. To achieve the hydrophobic effect, the fillers are preferably correspondingly surface-treated with known silicone compounds. Preferably an alkylsilane or alkenylsilane or an alkylsiloxane or alkenylsiloxane. This surface treatment can be carried out "in situ", for example by adding water, by adding silazanes, for example hexamethyldisilazane and/or 1, 3-divinyltetramethyldisilazane. So-called "in situ" hydrophobic interactions are preferred. It is also possible to work with other commonly used filler treating agents, for example vinylalkoxysilanes such as vinyltrimethoxysilane, other silanes with unsaturated organic functional groups such as methacryloxypropyltrialkoxysilanes, epoxyalkyltrialkoxysilanes or mercaptoalkyltrialkoxysilanes. Polyorganosiloxane diols with chain lengths of 2 to 50, with unsaturated organic or other organic functional groups to provide reactive sites for the crosslinking reaction are also known. Examples of commercially available silicates which have been hydrophobicized beforehand by means of various silanes are Aerosil R972, R974, R976 or R812 or, for example, HDK2000 or H30. Typical trade names for the so-called hydrophobic precipitated silicates (wet silica (wetsilica)' in english) are Sipernat D10 or D15 from Evonik corporation. These silicates which have been hydrophobized beforehand are less preferred than silicates hydrophobized "in situ" by means of silazanes. The mechanical properties and rheological properties of the rubber (i.e. the technical processability of the silicone rubber compound) can be influenced by the choice of the amount of filler type, its amount and the type of hydrophobic interaction. More preferred fillers are the highly transparent silicates produced by hydrolysis and condensation of tetraalkoxysilane and hexamethyldisilazane and/or 1, 3-divinyltetramethyldisilazane. For the purpose of illustration, US4344800, which exemplarily defines these silicates, is cited.

For the preparation of shaped articles from photocurable polymer compositions, these are preferably selected from compositions comprising:

a)100 parts by weight of a polyorganosiloxane (A) containing at least one alkenyl group and having a viscosity in the range from 0.01 to 100 pas (25 ℃, a shear rate gradient D of 1 s)^-1)，

b) From 0.5 to 1000ppm, calculated as metal, based on the amount of components (A) to (B), of at least one photoactivatable hydrosilylation catalyst (B),

c) optionally one or more sensitizers,

d) optionally from 0.0001 to 2wt. -% of one or more inhibitors, and optionally further auxiliaries, based on the amount of components (A) to (E),

e) 0.1 to 200 parts by weight of at least one polyorganohydrogensiloxane (E) bearing 0.5 to 20mol, preferably 1 to 5mol, of SiH groups per mol of alkenyl groups is used in (A),

f)0 to 100 parts by weight of one or more fillers.

These polyorganosiloxane compositions can also be cured in a short time with UV light in bulk irradiation with a large layer thickness or volume in the molding unit of the invention and can be removed from the mold without major sticking problems.

The integral irradiation unit of the present invention for curing the above-described photocurable polymer composition includes one or more ultraviolet light sources.

In the context of the present invention, the term ultraviolet light refers to electromagnetic (actinic) radiation which may affect the curing of flowable photocurable polymer compositions, especially silicone rubber compositions. The term "photo-activatable" refers to "photo (light) activatable" which includes, for example, indirectly photo-activatable groups activated by a photo-activatable catalyst. It is preferred to use ultraviolet light having a maximum in the spectral distribution in the wavelength range of 300 to 500nm, in particular in the wavelength range of 300 to 400 nm.

The UV light sources according to the invention include in particular those in which the proportion of the total radiation in the range > 700nm is less than 15%, and in the range < 300nm is less than 15%.

The total radiation referred to herein refers to the portion of the radiation that impinges on the transparent element of the integral irradiation unit. The term uv source therefore includes all elements of the illumination unit, including optional wavelength sensitive filters or dichroic mirror elements, which serve to additionally deviate the IR radiation from the radiation path used.

Thus, a source of ultraviolet light in which less than 15% of the total radiation fraction in the > 700nm range and less than 15% in the < 300nm range is characterized by providing radiation substantially in the region of the spectrum that affects the activation of the photocurable polymer composition. The wavelength range is the wavelength range at which the reaction rate of activation or curing of the photocurable polymer composition is at a maximum. The wavelength range depends on the photocurable polymer composition used, the catalyst used for this purpose, the inhibitor, the sensitizer, etc. For polymer compositions curable by hydrosilylation and preferred according to the present invention, the region of maximum activation or highest cure rate is about 345 to 385 nm. By using a UV light source with a particularly low radiation fraction in the range > 700nm and < 300nm, on the one hand the high-energy UV fraction, which is harmful to certain materials of the transparent element (transparent material), is reduced, while also the fraction of thermal radiation, which is harmful to both the transparent material and the photocurable polymer composition, is avoided. As mentioned at the outset, high-energy uv radiation (wavelength range < 300nm) affects in particular the premature aging of transparent plastic molding materials (for example from PMMA), which is manifested by yellowing, embrittlement and deformation, and ultimately by failure of the mold cavity, and leads to high production costs. The thermal radiation of the uv light source in the wavelength range > 700nm leads to possible deformations of the transparent element or the mould cavity, which makes it unusable, which can however be reduced according to the invention. By using a uv light source with a fraction of total radiation inherently in the > 700nm range of less than 15% and in the < 300nm range of less than 15%, for example a uv LED lamp with a maximum radiation range between 300 and 450nm and a narrow width of the radiation distribution, for example +/-25nm, and the energy used is the maximum amount converted into radiation for activation, which makes the energy utilization of the process very efficient.

The total radiation dose of the uv light source in the range > 700nm and < 300nm can be determined, for example, by irradiation with a suitable measuring instrument, in particular a (spectro) photometer, photocell or bolometer.

Ultraviolet light sources that meet these requirements include ultraviolet lamps, ultraviolet LEDs and ultraviolet laser light sources, particularly with wavelength selective filters and/or mirrors. Thus, in principle all conventional uv lamps used are suitable as uv light sources, preferably uv light sources whose radiation energy in the wavelength range < 300nm and > 700nm is suitably limited, or those uv lamps whose uv radiation is already provided by the system in a narrow wavelength range, such as uv LED lamps or uv lasers. Examples of conventional uv lamps are: ultraviolet fluorescent lamps, high-pressure mercury lamps, ultraviolet arc lamps, metal halide lamps, xenon lamps, flash lamps, undoped or Fe-or gallium-doped mercury lamps, black-light lamps, whose radiation is preferably suppressed in the range < 300nm and > 700nm, in particular by using wavelength-selective filters and/or mirrors. Examples of ultraviolet lamps that already provide radiation in a narrow wavelength range due to the system include, for example, ultraviolet LED lamps or ultraviolet laser lamps, such as excimer laser lamps. Superior foodThese were chosen because their thermal development was already low. The preferred lamp source according to the invention is especially selected in that the absorbed energy is converted as completely as possible into uv light usable for photocuring. These light sources already have a reduced heat radiating portion. Preferably, the fraction of heat radiation between 700-10000nm is less than 10% of the total radiation. Although the amount of thermal radiation can be reduced by up to 85% by shielding of the wavelength selective mirror or filter, this effect is not always sufficient to prevent unwanted high heat of the heat-sensitive transparent shaped element. This is where the present invention is treated by providing a liquid layer. According to the invention, the light source is preferably selected from the group of ultraviolet LED lamps and ultraviolet lasers. Examples of such light sources are ultraviolet LED lamps, e.g.Company LED Powerline and LED PowerPen, Dr.An LED lamp from Ettlingen or from Phoseon Technology, such as the FRDA202, FRDA75 model. In addition, UV lasers from, for example, the company Crystal Laser Systems Berlin, such as the FDSS355-300plus model or UV lasers having equivalent energy in the UV wavelength range to that of the Micro Optics LIMO Lissotschenko Mikrooptik GmbH from Dotmond, are particularly suitable. The laser light source preferably also requires a micro-optics for spatial distribution or enlargement of the tightly bundled laser beam before the transparent element of the integral shaping and irradiation unit. The radiation source generates ultraviolet light having a maximum in the wavelength range of 300-500nm, preferably 250-400nm, more preferably 320-385 nm. Conventional ultraviolet lamps in which the selected ultraviolet spectrum is produced by using suitable filters and dichroic mirrors are included as inIs/are as followsCompany UV Print HPL. By usingAn ultraviolet LED radiation source, preferably a narrow wavelength range of ± 20nm around the ideal peak, can be selected for the individual photo-activatable polymer compositions and then make more than 80% of the incident radiation practically available for photo-curing. For example sigma platinum catalyst (B) may preferably be activated by an LED uv light source in the 365 ± 20nm range. The UV light source used advantageously has an energy of 0.1-12000mW/cm². In order to reach the area to be irradiated completely, a plurality of such radiation sources may be arranged in the overall irradiation unit, which are connected if necessary to form a flat radiation combination. The mold used to receive the photocurable polymer composition may be partially or completely transparent or opaque to ultraviolet light. If irradiation of the photocurable polymer composition takes place outside the mold cavity, as previously described, for example in the injection channel, the case of opaque molds may also occur, which requires a correspondingly long shelf life or gel time of the photocurable polymer composition to transfer the irradiated polymer composition into a mold cavity that has not previously been cured to such an extent as to prevent transfer to the mold cavity. The mold cavity may be formed of conventional materials such as ceramics, metals, plastics and/or glasses, the surfaces of which themselves or with suitable equipment prevent adhesion of the cured polymer composition. The choice of the mould cavity material is therefore dependent inter alia on the viscosity or the mutually limiting solubility of the polymer compositions to be cured. For example, in the preferred case of photocurable silicone compositions, non-stick mold cavity materials of transparent materials such as poly (meth) acrylates and/or opaque materials such as optionally covered with metal are used. Conversely, in the case of the use of photocurable polymer compositions based on acrylates, in particular mold cavities based on transparent silicone and/or optionally covered with metal or transparent plastic are used. Easily processable materials such as plastics or metals are preferred. If the mould cavities are partly or completely formed by transparent elements, they are preferably made of a transparent plastic, for example the following transparent plastics for transparent elements. If the mold cavity is only partially formed of transparent elements, or is completely opaque, the opaque elements are preferably formed of metal. Size of die cavityDepending on the shape to be built. In general, the irradiation unit of the present invention may be provided in any size as long as the size is selected to allow sufficient radiation curing of the photocurable polymer composition. Thus, the mold cavity may have a longest dimension of up to 10m and a volume of up to 300 liters during casting, e.g. for receiving a large volume of electrical isolator parts. The longest dimension of the shaped article may be more than 0.5m, preferably more than 1 m. For large volumes, preferably at least about 0.5 liters, more preferably at least about 3 liters, and even more preferably at least about 10 liters. In particular, the best results for large volume moldings of at least about 20 liters can be achieved by the irradiation unit of the invention, since the required high radiant energy can be provided with low thermal development without any adverse effects on the mold cavity or the transparent element, i.e. thermal deformation, stress cracks or adhesion. For these large size castings, the shortest diameter is typically about 1cm, preferably at least about 5cm, and more preferably at least about 10 cm. In another embodiment, very small moldings, down to the microliter range, can also be produced by injection molding processes. These moldings have, for example, a volume of 0.001 to 500ml and a minimum thickness of 0.01 to 10 mm. The use of compact irradiation and moulding units is also advantageous here, since in this size range, injection moulding machines can advantageously be used which enable substantially automated production of uv-cured mouldings. It must be possible to open the mold cavity to remove the molding. This means that they are often formed by at least two interconnected but separable shaped elements, which often have one or more mould parting planes. After curing the photocurable polymer composition, the shape-imparting elements are separated from each other and the cured molded body or form may be removed. This can take place automatically, in particular by means of a correspondingly placed blockage or by using compressed air.

The material for the transparent layer that may optionally form the mold cavity completely is, for example, selected from the group consisting of: acrylates, especially polymethyl methacrylate (PMMA), for exampleRoehm & Haas Evonik, polyethylene Dicyclopentadienyl polymers (COC), for exampleSuch asMitsui ChemicalsCOC、DEW, quartz glass, for example, the nameIn EuropeCompany name ofThe Polymethacrylimides (PMMI) thus partially imidized methacrylic polymers, such as polyorganosiloxanes from Momentive Performance Materials, may optionally be surface-covered non-adhesively. Among other factors, industrial grade PMMA has been found to be unusable because of its excessive uv light absorption. The class of highly uv-transmissive PMMA is very suitable, wherein especially uv-stabilizers are substantially excluded in the production. Examples of these types of PMMA include0218. Similar uv-absorbing additives must preferably be avoided or replaced by suitable low-absorbing additives in other materials used for producing the transparent element or must be avoided altogether. The uv transparent layer is sized to withstand the in-mold pressure (e.g., a thickness of at least about 1mm, preferably at least 5mm, more preferably at least about 25 mm). At the same time, a sufficiently large channel area for the irradiation of the uv light must be provided to enable sufficiently fast curing. The required channel area is determined by the required UV radiation energy, the required curing time, the existing energy of the UV light source, to carry out the green-forming with an economically meaningful cycle time of 1-600 s/formAnd (4) producing. Up to 12W/cm²And 0.1 to 1 x 10⁴cm²Preferably 1-100cm²A transparent channel region for the ultraviolet light per lamp or per lane is advantageous. In order to increase the radiation transmission through the transparent layer and to shorten the curing time, light from a plurality of uv light sources may be used, in particular by using suitable mirrors and/or lenses. This may be particularly necessary in the case of small transparent elements, since the surface thereof is too low for receiving the light of several uv light sources. In other words, focusing is useful in those cases where the radiation surface of the ultraviolet light source is larger than the ultraviolet light transmitting area of the transparent layer. The transparent layer, such as may be used to build the entire mold cavity or just a portion of the transparent cavity, is open to light entry through the transparent layer. To enhance the radiation effect, the illumination unit of the present invention may optionally comprise one or more light guiding and/or reflecting elements. This embodiment is suitable, for example, in the case of a mold cavity having a shaded region, for example, by directing ultraviolet light into an insert present in the mold cavity of a desired region of the mold cavity or a photocured material present therein by reflection or light guiding. Suitable light directing and/or reflecting elements include, for example: the reflective member is, for example, a spherical reflective member that generates concave light reflection, or a surface-shaped reflective member, a light guide such as an optical fiber bundle, or the like. The light directing and/or reflecting elements may be located outside of the mold cavity and within the mold cavity, and are thus part of the present design. Thus, for example, in the case of a shaped cavity, a correspondingly shaped ball reflecting element may be placed within the mold cavity.

As mentioned above, the irradiation unit preferably has an injection passage for one or more photocurable polymer compositions, which enables the photocurable polymer composition to be injected into the mold cavity, optionally prior to or simultaneously with irradiation. The diameter of the injection channel is for example about 0.5 to 8mm, based on the desired injection rate (volume/unit time). The size of the door or door chain is preferably in the range of 0.2-10 mm. The present mould cavity (preferably cooperating with the injection channel) must be under a pressure difference with the external pressure in order to enable, inter alia, a windless filling of the mould cavity. The pressure difference may be, for example, at least about 0.1bar, preferably at least about 0.5 bar. This includes filling under vacuum applied to the mold cavity. Furthermore, the irradiation and molding unit may have a vent channel for venting the mold cavity during filling to provide a bubble-free molded object. The diameter of this vent passage may be, for example, at least about 1 mm. In addition, the parting line of the present mold cavity can be used for venting.

The invention further relates to the use of the irradiation and shaping unit according to the invention for the production of polymer shaped bodies or polymer coverings, such as seals, bulk electrical insulators (e.g. high-voltage insulators), field control elements, thyristors, cable insulators, cable jackets, photocouplers for light conductors, which are optionally composed of various materials, such as conductive, opaque elastomers, thermoplastics, which are placed in advance in a casting mold cavity, carrier materials containing active ingredients, laminates, cable insulators, seals for food containers made of metal or plastic, etc.

Preferably, the polymer molding or polymer coating obtained by using the integral irradiation unit of the present invention is derived from a silicone material.

By the irradiation and molding unit method of the present invention, various molded articles can be easily produced from a photocurable polymer material with high productivity. Such molded articles may be, for example: seals, for example gaskets with carrier layers, O-rings, cable insulators, insulators or other moldings.

The following summarizes again preferred embodiments of the invention:

1. an irradiation or molding unit for curing a photocurable polymer composition, comprising:

-one or more UV-light sources for irradiating at least one transparent layer in contact with the photocurable polymer composition and located between the UV-light source and the photocurable polymer composition,

-at least one casting mold for receiving a photocurable polymer composition, and

-at least one liquid layer located between the transparent layer and the one or more uv light sources and not permanently fixed to the uv light sources.

2. The irradiation unit according to the foregoing embodiment 1, characterized in that the thickness of the liquid layer is between 0.01mm and 50 mm.

3. An irradiation unit according to the preceding embodiment 1 or 2, characterized in that the thickness of the liquid layer is dimensioned to absorb at least 70% of the portion of the total radiation of the uv light source in the range > 700 nm.

4. The illumination unit according to one of the preceding embodiments 1 to 3, characterized in that the liquid layer is in contact with the transparent layer and the ultraviolet light source.

5. The irradiation unit according to one of the preceding embodiments 1 to 4, characterized in that a spacing in the range of 1 to 150mm is provided between the ultraviolet light source and the liquid layer.

6. The irradiation unit according to one of the preceding embodiments 1 to 5, characterized in that a method for exchanging liquid in a liquid layer is provided.

7. The irradiation unit according to one of the preceding embodiments 1 to 6, characterized in that the mass flow rate in the liquid layer is at least 0.1g/(min cm)²)。

8. The irradiation unit according to one of the preceding embodiments 1 to 7, characterized in that the liquid layer is in contact with the transparent layer.

9. The irradiation unit according to one of the preceding embodiments 1 to 8, characterized in that the liquid layer is located between and in contact with the transparent layer and the transparent cover layer.

10. An irradiation unit according to one of the preceding embodiments 1 to 7 and 9, characterized in that the liquid layer is located between two transparent cover layers located between the ultraviolet light source and the transparent layer.

11. The irradiation unit according to the foregoing embodiment 10, characterized in that the cover layer facing away from the ultraviolet light source is in contact with the transparent layer.

12. The irradiation unit according to one of the foregoing embodiments 1 to 11, characterized in that the liquid layer is in contact with a heat exchanger to dissipate heat.

13. The irradiation unit according to one of the preceding embodiments 1 to 12, characterized in that the liquid of the liquid layer absorbs IR radiation.

14. The irradiation unit according to one of the preceding embodiments 1 to 13, characterized in that the liquid of the liquid layer is transmissive for ultraviolet radiation.

15. The irradiation unit according to one of the preceding embodiments 1 to 14, characterized in that the liquid of the liquid layer is selected from the group consisting of: water, fatty alcohols, hydrocarbons, ionic liquids and salts, and mixtures thereof.

16. The irradiation unit according to one of the preceding embodiments 1 to 15, characterized in that the liquid of the liquid layer comprises at least one IR absorbing additive.

17. The illumination unit according to one of the preceding embodiments 1 to 16, characterized in that, furthermore, a non-liquid based IR radiation filter is located between the ultraviolet light source and the transparent layer.

18. The illumination unit according to one of the preceding embodiments 1 to 17, characterized in that the portion of the total radiation of the uv light source in the range > 700nm is less than 15% and the portion in the range < 300nm is less than 15%.

19. The illumination unit according to one of the preceding embodiments 1 to 18, characterized in that it comprises one or more light guiding and/or reflecting optical elements.

20. The irradiation unit according to one of the preceding embodiments 1 to 19, characterized in that it comprises one or more injection channels for the photocurable polymer composition.

21. The irradiation unit according to one of the preceding embodiments 1 to 20, characterized in that the ultraviolet light source is selected from the group consisting of: ultraviolet fluorescent lamps, high-pressure mercury vapor lamps, ultraviolet arc lamps, metal halide lamps, xenon lamps, flash lamps, undoped or Fe-or gallium-doped mercury lamps, and black light lamps.

22. The illumination unit according to one of the preceding embodiments 1 to 21, characterized in that the distance between the liquid layer and the ultraviolet light source is fixed or variable.

23. The irradiation unit according to one of the preceding embodiments 1 to 22, which is composed of several sub-components that can form an assembly of irradiation units.

24. The irradiation unit according to one of the preceding embodiments 1 to 23, having one or more injection channels.

25. The irradiation unit according to one of the preceding embodiments 1 to 24, characterized in that the transparent layer is part of a mold for receiving the photocurable polymer composition and/or part of one or more injection channels.

26. The irradiation unit according to one of the foregoing embodiments 1 to 25, characterized in that the transparent layer is in contact with a photocurable polymer composition composed of a thermoplastic polymer material.

27. The irradiation unit according to one of the foregoing embodiments 1 to 26, wherein the mold for receiving the photocurable polymer composition is composed of a thermoplastic polymer material.

28. The irradiation unit according to one of the preceding embodiments 1 to 27, wherein the mold for receiving the photocurable polymer composition includes an opaque portion.

29. The irradiation unit according to one of the foregoing embodiments 1 to 28, comprising a plurality of ultraviolet light sources.

30. The irradiation unit according to one of the preceding embodiments 1 to 29, wherein the radiation of the uv light source is at least 0.1mW/cm²。

31. The irradiation unit according to one of the preceding embodiments 1 to 30 for the continuous or batch production of cured polymer molded articles or for the production of articles having a cured polymer layer.

32. The irradiation unit according to one of the foregoing embodiments 1 to 31, wherein the photocurable polymer composition is a photocurable silicone composition.

33. A sub-assembly of the illumination unit according to any of the preceding embodiments 1 to 32, which does not comprise an ultraviolet light source.

34. A molding unit for curing a photocurable polymer composition, comprising:

-at least one casting mold for receiving a photocurable polymer composition,

-at least one transparent layer in contact with the photocurable polymer composition and transmissive to ultraviolet radiation, and

-at least one liquid layer arranged to be illuminated by illumination of the transparent layer.

35. A method for preparing a cured polymer molded article or an article covered with a cured polymer, wherein one or more photocurable polymer compositions are cured by using one irradiation unit according to the foregoing embodiments 1 to 32 or the molding units according to embodiments 32 and 33.

36. The method of embodiment 35, comprising the steps of:

a) optionally, the components of the irradiation unit are assembled,

b) optionally inserting one or more articles to be coated into a mold for receiving the photocurable polymer composition,

c) optionally introducing one or more photocurable polymer compositions into at least one or all of the existing molds through one or more injection channels,

d) irradiating the photocurable polymer composition through the transparent layer in the region of the injection channel and/or the mold for receiving the photocurable polymer composition,

e) the cured polymer form or polymer cover is removed continuously or in batches.

37. The method of embodiment 36, additionally comprising the steps of:

a) the range of effective wavelengths for activating curing is determined,

b) the uv light source with the largest radiation is selected in the effective wavelength range.

38. The method of embodiment 37, wherein the effective wavelength is in the range of 345 to 385 nm.

39. Use of the irradiation unit according to any one of the preceding embodiments 1 to 32 or the molding units according to embodiments 32 and 33 for producing a polymer molded article or a polymer cover.

The embodiments and examples are merely for describing the present invention, and are not intended to narrow the spirit and scope of the present invention.

Examples

Example 1

Catalyst mixture (B)

10000 parts by weight of a linear vinyl-terminated polydimethylsiloxane (a1) having a viscosity of 1Pa · s at 25 ℃ and a vinyl content of 0.13mmol/g are mixed with 1 part by weight of trimethyl (methyl) cyclopentadienylplatinum (platinum content 61.1%) from fa. The catalyst mixture containing 0.006wt. pt metal must be stored protected from light.

Example 2

Preparation of the base mixture

In the kneading machine, the raw materials are mixed,13.5 parts by weight of a dimethylvinylsiloxy-terminated polydimethylsiloxane having a viscosity of 10 pas at 25 ℃ (A1), 24.6 parts by weight of a dimethylvinylsiloxy-terminated polydimethylsiloxane having a viscosity of 65 pas at 25 ℃ (A1), 4.5 parts by weight of hexamethyldisilazane, 0.04 parts by weight of 1, 3-bis-vinyltetramethyldisilazane and 1.5 parts by weight of water are mixed and then reacted with a BET surface area of 300m²17.2 parts by weight of pyrogenic silica (F) per g were mixed, heated to about 100 ℃, stirred for about 1 hour, then water and excess silazane/silanol precipitate were liberated by evaporation at 150 to 160 ℃ and finally with a vacuum of p ═ 20 mbar. Next, the mixture was diluted with 17.4 parts by weight of a dimethylvinylsiloxy terminated polydimethylsiloxane (A1) having a viscosity of 10 pas. The starting materials for producing the following component mixtures were obtained.

Component mixture 2-1

0.3 parts by weight of catalyst (B) having a Pt content of 0.006wt. -% as obtained in example 1 was added under yellow light (excluding light below 700 nm) to the base mixture obtained above (about 89.5 parts by weight).

Component mixture 2-2

20.8 parts by weight of a mixture of trimethylsiloxy-terminated polymethylhydrogensiloxane (E) having a viscosity of 35 pas at 25 ℃ and a SiH content of 7.4mmol/g and of the formula M₂D₂₀D^H ₁₀The crosslinking agent of (2) was added to the base mixture (89.5 parts by weight) obtained above, and thoroughly mixed into the base mixture.

The component mixtures 2-1 and 2-2 of example 2 were fed into a static mixer by means of a plunger metering pump from the company 2KM in a volume ratio of 90: 110, where they were mixed with one another. The mixture is then transferred into the mold cavity of a separate mold.

EXAMPLE 3a preparation of high Voltage Shielding elements

The mixture of example 2 was injected at a temperature of 20-30 ℃ through an injection pipeIn the casting mould according to fig. 5, the charge is carried out in about 300s and a pressure of 3bar is maintained by the piston transfer unit. The volume of the cavity (4) is 3000 ml. The transparent casting mould (5) is completely made of a material derived from EvonikFrom GmbHGS colorless type 0218 PMMA (thickness 10mm, height 250 mm). The metal mould wall (6) comprises elements (1) to (2) and (4) to (5) which together form a cover for the present irradiation and shaping unit.

At a distance of 20mm from the cooling channel (1), the intensity in the wavelength range of 345-385nm of the maximum of the radiation is 40-80W/cm²Is irradiated perpendicularly from an ultraviolet lamp to a cooling channel (1)120s with two PMMA overlays using an ultraviolet lamp having a selected ultraviolet spectrum (less than 15% of the total radiation in the > 700nm range, less than 15% of the total radiation in the < 300nm range) under the model uva pnnt500hpl.fa.(2) Equipped with a H1 quartz envelope, air cooling and dichroic mirrors and a uv filter for deflecting IR radiation. The liquid layer of the cooling channel (1) has a thickness of 5mm and an irradiation area of 200cm². The mixture is added into water with the temperature of 20 ℃ to be 5g/(min cm)²) Is pumped through the cooling channel. The heated water is led back through the heat exchanger after cooling. After 80 rounds of irradiation, the temperature of the side of the uv transparent insert facing the uv light source reached about 60 ℃ as the formed silicone molded article was simply removed. The cooled acrylate casting mold can be used more than 100 times without visible damage. The PMMA derived cover layer towards the light source also surprisingly shows no visible deformation and yellowing. No significant reduction in cure rate occurred. After a 120s irradiation period, the molded article in the mold cavity (4) was crosslinked to such an extent that a hardness Shore a of 25 degrees was measured on the surface, and the molded article was removed. To is coming toAnd removing the formed product, turning off the ultraviolet light source until the next feeding, namely turning the switch to the standby state, so that the casting mold is not irradiated. The resulting molded article had neither bubbles nor a sticky surface.

Example 3b (comparative example)

Example 3a was repeated, with the difference that the irradiation was carried out without cooling channels. After the 80 rounds of irradiation, the temperature of the side of the uv transparent insert facing the uv light source reached about 80 ℃ as the formed silicone molded article was simply removed. After 100 irradiation cycles, the acrylate casting mold which had not been cooled exhibited deformation of the surface of the casting mold made of PMMA facing the side facing the uv light and yellowing of the irradiated area. The uv transparency is significantly reduced and small cracks appear on the surface.

Claims (15)

1. An irradiation and molding unit for curing a photocurable polymer composition, comprising:

-one or more UV-light sources for irradiating at least one transparent layer, said transparent layer being in contact with the photocurable polymer composition and being located between the UV-light source and the photocurable polymer composition,

-at least one casting mold for receiving a photocurable polymer composition, and

-at least one liquid layer located between the transparent layer and the one or more uv light sources and not permanently fixed to the uv light sources.

2. The irradiation and shaping unit of claim 1, wherein the liquid layer has a thickness between 0.01mm and 50 mm.

3. The irradiation and shaping unit according to any one of claims 1 to 2, wherein the liquid layer is in contact with the transparent layer.

4. The irradiation and shaping unit according to any one of claims 1 to 3, wherein the liquid layer is located between and in contact with the transparent layer and the transparent cover layer.

5. The illumination unit according to any of claims 1 to 2, wherein the liquid layer is located between two transparent cover layers located between the ultraviolet light source and the transparent layer.

6. The irradiation and shaping unit according to any one of claims 1 to 5, wherein the liquid of the liquid layer absorbs infrared radiation.

7. The irradiation and molding unit of any one of claims 1 to 6, comprising one or more injection channels for the photocurable polymer composition.

8. The irradiation and shaping unit according to any one of claims 1 to 7, wherein the ultraviolet light source is selected from the group consisting of: ultraviolet fluorescent lamps, high-pressure mercury vapor lamps, ultraviolet arc lamps, metal halide lamps, xenon lamps, flash lamps, undoped or Fe-or gallium-doped mercury lamps, and black light lamps.

9. The irradiation and molding unit of one or more of claims 1 to 8, wherein the transparent layer is part of a mold for receiving the photocurable polymer composition and/or is part of one or more injection channels.

10. The irradiation and molding unit of any one or more of claims 1 to 9, wherein the transparent layer is in contact with a photocurable polymer composition comprised of a thermoplastic polymer material.

11. The irradiation and molding unit of any one or more of claims 1 to 10, wherein the photocurable polymer composition is a photocurable silicone composition.

12. A molding unit for curing a photocurable polymer composition, comprising:

-at least one casting mold for receiving a photocurable polymer composition,

-at least one transparent layer in contact with the photocurable polymer composition and transmissive to ultraviolet radiation, and

-at least one liquid layer arranged to be illuminated by illumination of the transparent layer.

13. A method for the preparation of a cured polymer molding or a cured polymer-covered article, wherein one or more photocurable polymer compositions are cured by using an irradiation unit according to any one of claims 1 to 11.

14. The method of claim 13, comprising the steps of:

a) optionally, the components of the irradiation unit are assembled,

b) optionally inserting one or more articles to be coated into a mold for receiving the photocurable polymer composition,

c) optionally introducing one or more photocurable polymer compositions into at least one or all of the existing molds through one or more injection channels,

d) irradiating the photocurable polymer composition through the injection passage and/or the transparent layer in the region of the mold for receiving the photocurable polymer composition,

e) the cured polymer form or polymer cover is removed continuously or in batches.

15. Use of an irradiation unit according to any of the preceding claims 1 to 12 for the production of polymer mouldings or polymer coverings.

Irradiation and shaping unit

The present invention relates to an irradiation and shaping unit having one or more uv light sources for curing a photocurable polymer composition. The irradiation and molding unit of the present invention enables polymer moldings or polymer coverings, especially silicone moldings, to be produced highly efficiently in a continuous or batch process. The irradiation and shaping unit according to the invention increases in particular the lifetime of transparent castings originating from polymeric shaping materials, in particular from polyacrylates. Polyacrylate moldings exposed to direct radiation (for example conventional UV light sources equipped with mercury lamps, having a broad radiation spectrum) deform, discolor after several moldings, reduce their UV transmittance at the irradiated surface and therefore have to be replaced up to now after a short period of use. This is uneconomical because of the luxury production of high-precision mold cavities or large-volume molds. However, depending on the cost of producing the casting mold from, for example, polyacrylate, it is desirable to have at least 50, preferably at least 100, molding or radiation curing applications without causing a significant decrease in ultraviolet transmittance and cure rate.

The irradiation and molding unit of the invention is particularly useful for the production of moldings derived from photocurable polymers, in particular for the production of elastomer moldings, thermoset moldings, thermoplastic moldings or moldings of thermoplastic elastomers.

In addition, the irradiation and molding unit of the present invention should be as small as possible, which is required for the construction of many injection molding machines. The irradiation unit of the invention is thus fastened to a correspondingly provided mold clamping device in an injection molding machine. In this position, machine controlled filling, opening and closing of the mold cavity of the photocurable polymer composition is possible. In contrast, a relatively large-volume irradiation unit would require a complex injection molding machine with a correspondingly large mold clamping device, which would have to be produced separately, resulting in a considerable increase in costs.

From the prior art, casting molds with transparent windows are known, which can be considered for the molding and chemical crosslinking of photocurable polymers. US5401155 describes a metal mold with a light-transmissive window at the front end, placed perpendicular to the light source. US6627124 claims a two-part mold for producing a lens body, wherein one half of the mold is made of a transparent material. US5885514 teaches a method of forming and curing a seal on a seal plate having a transparent upper portion and a lower mold half. US2007/141739a1 discloses curing of silicone molding for encapsulation of light emitting diodes (LED's).

Since conventional light sources generate much heat, the production of larger moldings with currently available light sources from photocurable polymers often requires a compromise between the available uv light transmission, the transparent element and the permissible irradiation light power. In order to provide an inexpensive, easily manufactured and durable light transmitting element, i.e. a window, the transparent material has to fulfill a range of requirements for light entry. They must allow as completely as possible the transmission of the ultraviolet light of the desired wavelength without absorption losses. They should in particular be easy to shape if they are part of a shaping mold cavity. This means that the desired contour of the mould wall should be designed and worked in a simple manner. On the one hand, quartz glass is an ideal ultraviolet light transmitting material, which is further heat and scratch resistant, however, it is difficult to form by surface processing and is expensive. Although a transparent element made of quartz glass can certainly be used as a mold cavity wall or access window in a mold in a manner that reduces mechanical stress and reduces the risk of breakage, this application is subject to certain conditions. The brittleness of the quartz glass and the adhesion between the quartz glass and some photo-curable polymers, by means of which it can be adhesively connected, must be taken into account. This complicates the separation of the shaped articles after curing. Other salt water glasses or mineral glasses have similar advantages and disadvantages. However, these materials are well suited for simply designed mold cavities or injection channels, where smaller planar workpieces can be inserted as transparent windows.

Transparent thermoplastics are considered as an alternative, which are not sufficiently heat-resistant and have a too short lifetime under the previously known conditions of ultraviolet irradiation. The light source used during uv irradiation affects the transparent shaping in different ways. On the one hand, the very short wavelength range of the ultraviolet radiation leads to destruction of the polymer structure, and on the other hand, the heat generation in the light source for ultraviolet irradiation or the amount of radiation in the IR range in particular leads to an increase in the heat generation in the transparent molding. The heating of the transparent casting material by the uv light source causes it to expand, which negatively affects the geometric accuracy of the shapes produced therein. The problem of heat generation is certainly more severe as the present irradiation and shaping unit is constructed more compact.

On the other hand, many transparent thermoplastics can advantageously be easily processed into shaped elements for use in the molding channel or in the mold cavity or for the mold cavity (mold cavity) in comparison with quartz glass.

The aim that the inventors of the present patent application set themselves to solve is therefore to provide an irradiation and moulding unit that is as compact as possible, but nevertheless stable, which is suitable for use in a wide variety of injection moulding machines.

One method initially involves cooling of the transparent casting mold used by contacting the mold with a suitable liquid coolant, rather than in the field of ultraviolet light transmission from ultraviolet lamps, which has heretofore been considered detrimental to curing. By this form of cooling, the heat is naturally dissipated at the interface between the cooling medium and the transparent casting mould. By heat conduction inside the molding material, partial heat dissipation in the region of the transparent casting mold is also achieved, which is transmitted by ultraviolet light. However, the heat dissipation achieved is still considered to be insufficient, of course, especially in areas not in direct contact with the liquid coolant, especially in transparent areas. The inventors of the present patent application have therefore sought to improve the cooling of transparent moldings, in particular of transparent moldings made from thermoplastic materials