Patent Application
20060177646
This invention relates to the subject matter in the preamble of patent claim 1 and is thus concerned with the production of fast UV-thermosetting substances, such as those used in the production of shatterproof panes of glass.
Shatterproof glass panes are known per se. As a general rule, they consist of two separated panes that are connected via a compound situated between them in order to provide a light-weight, shatterproof structure. The automobile industry already produces shatterproof glass by pouring casting resin between two panes that can be made of flat glass (float glass) and/or plastic. The casting resin is then cured by UV irradiation, which then produces the bond.
In order to achieve a thorough curing, very strong UV emitters and undesirably long irradiation times are required. This increases the cost of the composition of shatterproof glass panes and thus limits usability. The same goes for other uses outside of production of shatterproof glass panes, in which compounds are changed by UV irradiation.
The object of this invention is to provide an innovation for commercial use.
The object is solved in the independent claims. Preferred embodiments can be found in the dependent claims.
Thus, in accordance with the first main aspect of the current invention, a method is suggested for the production of shatterproof glass panes, in which an initial body is provided between the panes and made to form a bond, whereby UV light from a broadband energy source is beamed onto the initial body and whereby the initial body is provided with an IR absorber before UV irradiation in order to absorb IR radiation in the initial body from the broadband energy source during the reaction and to absorb heat in the cured compound of the shatterproof glass.
It is important to note here that the curing can be accelerated by the presence or addition of only a very small amount of infrared absorber. This realization is not limited to the production of shatterproof glass panes, but does provide particular advantages in that field. The addition of an IR absorber to a compound to be cured thereby significantly reduces the irradiation time with the same hardening results, even though the actual curing itself does not take place through heating, but rather through a transformation activated in another field, which offers considerable advantages with respect to systems engineering and production times. The process thereby takes advantage of the fact that the typically used energy sources for the UV irradiation of the initial body work in a broadband manner, as is the case in metal vapor discharge lamps, in particular mercury vapor discharge lamps, whereby UV and IR are irradiated simultaneously.
The initial body thereby typically comprises a compound with a UV-sensitive photoinitiator that has in particular a certain, not-too-low sensitivity to temperature i.e. that runs through the desired hardening reaction faster and/or different due to UV light at different temperatures. Compounds or photoinitiators particularly suited for the purposes of the invention have a large variation in their sensitivity to temperature.
In a preferred embodiment, the IR absorber is UV resistant in order to be active over the entire irradiation period, as opposed to the photoinitiator, which is typically broken down over the course of the curing or transformation of the initial body. Due to the significant and measurable increase in temperature over the course of the reaction due to the IR absorption, the initial body or the reacting photo-sensitive components of the initial body can compensate for the decrease in concentration due to the break-down of the photoinitiator such that increased reaction speeds result for the respective still remaining amounts of the photoinitiator. Even with low amounts of the suitable absorber, the heating is already so much faster that it remains limited at least locally to the initial body, which is advantageous because no or at least no significant coupling of heat into objects to be glued, sealed, or effused takes place, in particular, if they only have a very low thermal conductivity like those panes typically used for shatterproof glass panes.
It is possible to use casting resin as the initial body, in particular casting resin based on acrylic or acrylate resin, which is preferred insofar as such initial bodies for ultraviolet, visible, and infrared light are sufficiently transparent or can be selected. The preferred use of inorganic infrared absorber is also possible in such compounds, namely in particular using dispersing aids that allow the preferred, very even distribution of particles that are very small in size in order to thus enable an even coupling of the IR irradiation. The infrared absorber can and is thus preferably distributed or dispersed homogeneously.
The IR absorber is preferably a transparent conductive oxide that is equipped with suitable dispersing agents, in particular ATO, ITO, ZnO, LaB6 and/or mixtures of and/or with these substances and/or such encapsulated substances and/or mixtures. Even with larger concentrations of these substances, it is possible to select the dispersing additives such that the IR absorber remains finely distributed in the initial body during the reaction so that it also absorbs heat in the cured compound of the shatterproof glass pane and is thus able to provide another typically desired property in addition to the acceleration of the hardening reaction and thus the reduction in the cost to produce the shatterproof glass pane. The IR absorber is typically nanoparticulate, i.e. it has sizes ranging from 10 nm to the μm range, each relating to their individual particle and/or agglomerate thereof in order to thus guarantee good distributability in the casting resin or its pre-stages.
However, in lower quantities, it is exactly these materials that have ideal properties for achieving the desired IR absorption during the reaction; the quantities of these materials can be held low enough in order to be able to avoid damage to potentially existing surfaces or volume properties such as static chargeability, transparency for radio waves, in particular for example, in the GSM bands.
The IR absorbers, initial bodies, and dispersing additives to be used greatly depend on the planned use of the panes or other material to be connected, sealed, or transformed. However, it is understood that changing initial bodies may require systems with different dispersing compounds. In this connection, also note that, in typical systems, the infrared absorber in this invention can be mixed with the casting resin in any order.
However, acrylates are preferably selected from the following group: 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipat di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, dicyclopentenyl di(meth)acrylate modified with caprolactame, phosphoric acid di(meth)acrylate modified with ethylene oxide, cyclohexyl di(meth)acrylate modified with an allyl group, isocyanurate di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate modified with propionic acid, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate modified with propylene oxide, tris (acryloxyethyl) isocyanurate, dipentaerythritol penta(meth)acrylate modified with propionic acid, dipentaerythritol hexa(meth)acrylate, dipentaeryhtritol hexa(meth)acrylate modified with caprolactam, (meth)acrylate ester monofunctional (meth)acrylate, such as methyl(meth)acrylate, ethyl(meth)acrylate, isopropyl(meth)acrylate, 2-ethylhyxyl(meth)acrylate butyl(meth)acrylate, cyclehexyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxy-propyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol polypropylene glycolmono(meth)acrylate, polyethylene glycol polytetramethylene glycol mono(meth)acrylate and glycol di(meth)acrylate; difunctional (meth)acrylate, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, allyl(meth)acrylate, bisphenol-A-di(meth)acrylate, ethylene oxide-modified bisphenol-A-di(meth)acrylate, polyethylene oxide-modified bisphenol-A-di(meth)acrylate, ethylene oxide-modified bisphenol-S-di(meth)acrylate, bisphenol-S-di(meth)acrylate, 1,4-butandiol di(meth)acrylate, and 1,3-butylene glycol di(meth)acrylate; and tri- and higher functional (meth)acrylate, such as trimethylol propane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythrite tri(meth)acrylate, pentraerythrite tetra(meth)acrylate, ethylene-modified trimethylol propane tri(meth)acrylate, dipentaerythrite hexa(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl acrylate, 2-ethylhexyl carbitol acrylate, omega-carboxypoly caprolactam monoacrylate, acryloyloxy ethyl acid, acrylic acid dimer, lauryl (meth)acrylate, 2-methoxy ethyl acrylate, butoxy ethyl acrylate, ethoxy ethyl acrylate methoxy triethylene glycol acrylate, methoxy polyethelene glycol acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, N-vinyl-2-pyrrolidon, isobornyl (meth)acrylate, dicyclopentenyl acrylate, benzyl acrylate, phenyl glycidyl ether epoxy acrylate, phenoxy ethyl (meth)acrylate, phenoxy (poly)ethylene glycol acrylate, nonylphenol ethoxylized acrylate, acryloyloxy ethyl phthalic acid, tribromophenyl acrylate, tribromophenol ethoxylized (meth)acrylate, methyl methacrylate, tribromophenyl methacrylate, methacryloxyethyl acid, methacryloyloxyethyl hexahydrophthalic acid, methacryloyloxyethylphthalic acid, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, beta carboxyethyl acrylate, N-methylol acrylamide, N-methoxy-methyl acrylamide, N-ethoxymethyl acrylamide, N-n-butoxymethyl acrylamide, t-butyl acrylamide sulfonic acid, vinyl stearate, N-methyl acrylamide, N-dimethyl acrylamide, N-dimethylaminoethyl (meth)acrylate, N-dimethylaminopropyl acrylamide, acryloylmorpholine, glycidyl methacrylate, n-butyl methacrylate, ethyl methacrylate, allyl methacrylate, cetyl methacrylate, pentadecyl methacrylate, methoxy polyethylene glycol (meth)acrylate, diethylaminoethyl (meth)acrylate, methacryloyloxyethyl succinic acid, hexanediol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol diacrylate monostearate, glycol diacrylate, 2-hydroxyethylmethacryloyl phosphate, bisphenol A ethylene glycol adduct actylate, bisphenol F ethylene glycol adduct acrylate, tricyclodecanemethanol diacrylate, trishydroxyethyl isocyanurate diacrylate, 2-hydroxy-1-acryloxy-3-methacryloxypropane, trimethylolpropane triacrylate, trimethylolpropane ethylene glycol adduct triacrylate, trimethylolpropane propylene glycol adduct triacrylate, pentaerythritol triacrylate, trisacryloyloxyethyl phosphate, trishydroxyethyl isocyanurate triacrylate, modified epsilon-caprolactam triacrylate, trimethylolpropane ethoxy triacrylate, glycerol propylene glycol adduct triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethylene glycol adduct tetraacrylate, di-trimethylolpropane tetraacrylate, dipentaerythritol hexa(penta)acrylate, dipentaerythritolmonohydroxy pentaacrylate, urethane acrylate, epoxy acrylate, polyester acrylate, unsaturated polyester acrylate.
Furthermore, the photoinitiator can preferably be selected from the following group: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenyl-acetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-on, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1-on, 4-(2-hydroxyethoxy)phenyl 2-hydroxy-2-propyl ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl-anthrachinone, 2-ethylanthrachinone, 2-tert-butylanthrachinone, 2-aminoanthrachinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthon, benzyl dimethyl ketal, acetophenone dimethyl ketal, and p-dimethylamine benzoate.
The quantity of infrared absorber, in particular of transparent, conductive oxide, is typically between 0.005 wt. % and 4 wt. % of the casting resin molding, whereby even lower amounts hardly contribute to significant improvements in the curing time, while with higher concentrations no additional advantage typically occur, assuming corresponding layer thicknesses. Moreover, it cannot be excluded that the overall stability of the shatterproof glass pane or other system does not remain the same or almost the same as without admixing.
But, particularly for very low concentrations, it is surprising that processing times can be decreased significantly, which in turn leads to an overall reduction in cost. This can then already be the case when such a low amount of absorber is used that no significant property changes result in the final product based on its presence alone. It should be noted that the IR energy flow from conventional UV lamps is considerably higher than in normal sunlight, so that good results can be obtained even though the absorption of IR is low for solar irradiation. The actual overall concentration can also be selected depending on the overall layer thickness and namely also with respect to a later required or desired heat absorption or the radiation absorption and/or the electrostatic properties of the finished shatterproof glass pane.
Protection is also required for a correspondingly equipped shatterproof glass pane as well as, in accordance with the invention, for an equipped casting resin, in particular a transparent and liquid casting resin, in particular based on an acrylate or an acrylic, which can, in particular, be consist of acrylic resin, acrylic acid, and methylmethacrylate. Protection is also in great demand for casting resin and other UV-curable compounds in which the absorber content based on the above, in particular ITO content and/or ATO content of under 0.4%, is in particular under 0.2%. Casting resins or other UV-transformable systems, which are not used in the production of shatterproof glass panes but which offer advantages with respect to very fast transformability with UV light without the addition of IR properties of the end product or similarly influential TCO amounts, can be realized with the invention.
The invention is described below using an example that refers to figures. The figures show the following:
Two panes made of inorganic flat glass are set at a distance of 1 mm from either other and sealed on the edges. Then a casting resin from a conventional mixture of acrylic resin, acrylic acid, and methylmethacrylate is poured into the gap. The fill-in hole is glued. Now the arrangement is exposed to UV light created by a broadband UV energy source, here a UV curing device made by Beltron. It is determined how many irradiation passes at an energy of 5000 mJ/cm2 are needed for complete curing. It is determined that eight passes are needed.
Two glass panes are again arranged at the aforementioned separation distance and sealed on the edges. 0.1 wt. % ITO is now incorporated into the casting resin as used before, before the liquid casting resin is poured between the panes. With corresponding irradiation with passes of, once again, 5000 mJ/cm2 in the UV curing device, only four passes are required for complete curing.
Transmission and absorption curves of the finished laminate compounds are then recorded for different layer thicknesses and ITO contents.
0.1 wt. % of a nanocrystalline ATO (SnO2:Sb) was incorporated into a casting resin as in exemplary embodiment 1. The transparent liquid was poured between two glass panes that were sealed on the edges and that had a separation distance of 1 mm (=gap). After filling the resin, the fill-in hole is glued. The same was done with the unmodified resin. Both samples were fed through a UV curing device (Beltron) for curing; the samples were exposed to an energy of 5000 mJ/cm2 per pass.
In the case of the unmodified resin, 8 passes were need for complete curing. The resin containing the ATP was completely cured after 5 passes.
An ATO powder is first encapsulated as an IR absorber: 100 g of a conventional ATO powder is pre-dispersed in 500 ml of deionized water. The dispersion is adjusted to a temperature of 75° C. by the dropwise addition of an ammonia solution with 2 mol NH3/l and a pH value of 8.5. Then a solution with a reactive orthosilicate is added dropwise to the dispersion under strong acoustic excitation (ultrasound) until the ration of orthosilicate to ATO has reached a value of 1:4 after 90 minutes. The dropwise addition takes place at a constant temperature and a pH held constant by the addition of a hydrochloric acid solution with 2 mol HCl/l. After the end of the dropwise addition, the fluid is cooled, the obtained solid is filtered off, washed and then dried for three hours at 100° C. The substance produced in this manner is reused as encapsulated ATO.
0.15 wt. % of this nanocrystalline ATO (SnO2:Sb), which was provided with a glass-like encapsulation, is incorporated into a casting resin as in exemplary embodiment 1; the share of the encapsulation amounted to 20 wt. % of the overall mass of the powder. The resulting transparent liquid was poured between two glass panes that were sealed on the edges and that were located 1 mm from each other (=gap). After filling in the resin, the fill-in hole was glued. The same was done with the unmodified resin.
Both samples were fed through a UV curing device (Beltron) for curing; the samples were exposed to an energy of 5000 mJ/cm2 per pass.
In the case of the unmodified resin, 8 passes were need for complete curing. The resin containing the encapsulated ATO was completely cured after 5 passes.
Based on the encapsulation, in particular the glass-like encapsulation of the inorganic IR absorber, here nanocrystalline TCO, the cured compound behaves biologically the same as compounds without such additives, so that it can be used for foodstuffs, etc. It is clear that the encapsulation is positive for use in foodstuffs, pharmaceuticals, or similar areas regardless of the actual encapsulated material, and the admixture of encapsulated IR absorber for curing or decreasing the irradiation time is advantageous for any UV-transformable compound.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102005005976.7 | Feb 2005 | DE | national |
