DE4212831A1 - Transparent form part with scratch-proof and anti-mist properties - comprises plate-shaped substrate and anti-mist layer with one lower edge left free - Google Patents

Abstract

The substrate (10) is of inorganic-silicate-glass or organic glass, pref. of polycarbonate provided on one of its surfaces with a scratchproof coating (14,16) of pref. polysiloxane. The substrate on one of its surfaces is provided with a photochrome zone (12), the transparency and/or colour tone alters dependent upon radiation with UV rays. An upper edge running parallel to the lower edge is provided which is not covered by the anti-mist layer (18). The form part is formed as a helmet visor with a glass substrate (10), the front surface of which is a complete photochrome zone (12) covered with a scratch proof layer (16) of polysiloxane. Likewise, the rearward surface of the substrate is completely covered with a scratchproof layer of polysiloxane. This rearward layer in its central section has an anti-mist layer (18). USE/ADVANTAGE - A helmet visor which is scratchproof and does not mist over.

Description

The invention relates to a preferably transparent molded part with scratch-resistant and anti-fog properties ("anti-fog") and a process for its production.

Such molded parts are used in numerous areas for example as sunroofs, spreading windows for headlights, window panes, especially in vehicle construction, Spectacle lenses, covers for electrical and electronic Devices, cladding and roof elements in the construction industry, Glazing in aircraft or boat building, and the like.

These molded parts are generally approximately plate-shaped, the plates being bent in one or more dimensions or can have any shape. you are preferably at least for visible light more or less transparent, so that one can pass through such molded parts can see, but can also, for example, opaque be casual or even reflective, such as Mirror. These molded parts have a carrier body, a so-called named substrate, made of glass, which either consists of "correct" Glass, so be (inorganic) silicate glass or the like stands, or from a plastic, what the name stands for has naturalized "organic glass". Examples of organic  Glasses are materials such as preferably polycarbonate, acrylic glass, PMMA (polymethyl methacrylate), CR39, and the like. While the inorganic glasses in themselves are already sufficient are scratch-resistant, the organic glasses must first be scratch-resistant be equipped, for example by coating with a Polysiloxane material, such as by dipping, flooding or Syringes is applied. The advantages of organic glasses are in their ability to form even complex shapes design, combined with their low weight in comparison to molded parts made of inorganic glass, even including the scratch-resistant coating.

For certain uses, such as window panes, glasses glasses, in particular for sports glasses, such as ski goggles, visors for (motorcycle) helmets and the like, the (organic or inorganic) glasses increasingly phototropic and / or Equipped photochromically, so that their transparency and / or color depending on the intensity of the incident Sunlight changes; the UV component is decisive here of light. This will counter a user's eyes protected against excessive light radiation, and also against glare. A color change can result in optimal contrast with changing Lead light conditions. The change in transparency and / or Color is created by a photosensitive, e.g. B. photochromic Zone of the substrate in which a photochromic Material diffuses at least partially into the substrate is.

A significant impairment of the good properties however, such glasses can occur if they are steamed up gene; every glasses wearer is aware of this problem, however also every motorcycle rider for whom there is even a hazard its security. Therefore, at (inorganic or organic) glasses often an additional anti-fog Layer of a suitable material applied. Here However, problems often arise with liability the anti-fog layer and / or their service life together  hanging. Either the anti-fog layers come off unpredictably after a relatively short time, at least partially, for example with the formation of gaps or bubbles, whereby the optical quality is significantly reduced and in particular which can cause severe glare from scattering. This is of course particularly important in traffic or when Sport is not only a hindrance, but a potential hazard tial. In addition, the anti-fog layers relatively soft and therefore not very resistant to abrasion; an only partial However, abrasion leads to the destruction of the anti-fog The layer then progresses particularly quickly. Also seem with a multi-layer structure of molded parts, with layers made of substrate, partially diffused photochromic zone, a scratch-resistant coating material and finally the Anti-fog coating often certain combinations of materials not being particularly well tolerated, though this can lead to the fact that the already relatively vulnerable Anti-fog layer peels off or gets damaged even faster is damaged or destroyed.

The invention has for its object improved moldings and to provide a process for their manufacture len, so that the moldings of the invention their longer retain beneficial properties.

The task is performed by a molded part with the characteristics of Claim 1 or a method with the in the claim 7 specified steps solved.

Advantageous embodiments of the invention are in the sub claims specified.

The inventive design of the molded part is the Based on the knowledge that so far the anti-fog layer, whether applied by dipping, flooding or spraying  has always covered the entire area of the Stretched substrate. The bottom end of the anti-fog Layer on the lower edge of the substrate (or the lower edge the layer covering this, such as a scratch-resistant coating layering on the substrate) "resulted from itself" or in other words, was poorly defined. Here you can namely uneven layer thicknesses occur particularly easily ten, but also (at least microscopic) blistering, Micro crater, or other "flaws" of the anti-fogging Layer, and such defects are more likely to damage and especially quickly after the start spread.

Furthermore, the inventors have recognized that the generic Moldings are often mechanically stressed at least on one edge will. Such problems occur with sights, for example for helmets because the visor is on when closed should be windproof against a sealing bead of the helmet, others on the other hand should be foldable; in practice it becomes one Visor often opened and closed and thereby through you mechanically stressed. In the form of the invention Part of the anti-fog layer is now not mechanical claimed, but in the marginal area the one below Layer that is scratch-resistant and therefore considerably more resistant is; the anti-fogging layer remains unaffected by this does.

The method according to the invention is first improved by a corona pretreatment to adhere the surface or layer on which the anti-fog layer is then applied brought. This will prevent the anti-fog Layer significantly improved and thus their resistance ability to damage increased.

However, it is not easy to apply an anti-fog layer  so that it covers the surface below or layer not completely covering, but at least an edge remains free. In particular you get as the bottom Completion of the anti-fog layer no clear, good on the adhesive surface underneath. It has surprisingly pointed out that it is possible with the measures specified in claims 15 to 18 to achieve excellent results. This appears all the more more astonishing, if you take into account that yes through the Corona pretreatment improves adhesion of the anti-Be impact layer is achieved, so that it is initially considered against this better adherent layer must appear to be verbal partially to form at least one edge again to solve. Especially with those specified in claims 16-18 However, measures will be a clearly defined, firmly adhering Edge of the anti-fog layer at the transition point to the Edge achieved. Weathering tests with natural and artificial Lich light (UV lamp) have shown that the Invention molded parts have a significantly longer usable life exhibit, especially with regard to the so far particularly susceptible anti-fog layer: this adheres better overall, is mechanically less or not used at all, and is also so smooth on the edges that there is no risk of damage blisters or craters are noticeable.

The invention is illustrated below with reference to drawings illustrated embodiments explained in more detail, from which further advantages and features emerge.

It shows:

Figure 1 is a plan view of the front of a plattenför shaped part according to the invention.

FIG. 2 shows a longitudinal section along line II of FIG. 1;

Figure 3 is a plan view of a visor, which is moved along a stationary corona treatment device. and

Fig. 4 is a view from within the curved visor on its inner circumference and four electrodes of the corona treatment device.

In Figs. 1, 2, a molding is illustrated schematically highly simplified according to the present invention for ease of explanation. A plate-shaped substrate 10 made of polycarbonate (PC) is provided with a photo-chromic zone 12 on one side, namely on its front side that later faces the light. In other words, the “sun” is arranged in FIG. 2 above the shaped body designated overall by reference numeral 20 , and the eye or eyes of the user is located below the shaped body 20 . The photo chrome layer can be applied by one-sided treatment of the substrate 10 , for example by one-sided, that is to say front-side spraying or flooding, or covering the (lower) rear side with a masking lacquer and subsequent dipping with a suitable photochromic material. Then heat treatment is carried out at 80-130 ° C, preferably at 120 ° C, for about 30 minutes (with PC as substrate material). Of course, the substrate can also consist of silicate glass. The shape of the molded part is in principle arbitrary, the shape of a flat plate in FIGS. 1, 2 was chosen only to simplify the illustration in order to clarify the essence of the invention.

A scratch-resistant coating 14 (front) or on all sides is now applied to the relatively scratch-sensitive PC material of the substrate 10, including the photochromic zone 12 , which has formed due to the heat treatment in that the photochromic coating material has at least partially diffused into the substrate 10. 16 (rear) brought on, easiest by immersing the molded part in a suitable material such as preferably polysiloxane. For certain applications, it may also be sufficient to form a scratch-resistant layer 14 on only one side, usually the front. The scratch-resistant layer, that is to say the applied polysiloxane lacquer, is then also subjected to a heat treatment, preferably about 120 minutes at about 120 ° C.

The production steps for applying the (inner or rear) anti-fog layer 18 then take place.

For this purpose, a corona treatment is first carried out in the manner shown in a highly simplified manner in FIGS. 3, 4. Corona treatment is already being used in a completely different technical field, namely in the preparation of polyethylene films for printing, for example for carrier bags that are to be provided with an advertising print, since otherwise the printing inks on the polyethylene material will not run properly. It must appear as surprising that a corona treatment with suitable parameters also with completely different materials, namely with scratch-resistant inorganic glass or a scratch-resistant layer made of polysiloxane on a polycarbonate substrate, for a subsequent coating with an anti-fog layer enables significant improvement in liability.

One suitable for the purposes of the present invention Corona treatment device is for example from the company ARCOTEC Oberflächentechnik GmbH in D-7251 Wimsheim at the name "arcojet 1.1A2". The electrodes voltage is 2 × 7 kV against earth, and the treatment area is 40 × 50 mm at standstill. Here the Elek radiate trod freely, i.e. without a ground-leading counter electrode.

The basic arrangement for the corona pretreatment of a visor 30 for a motorcycle helmet is shown in FIGS. 3, 4. The visor 30 is curved in the usual way for use in so-called full-face helmets and is provided at both ends with a swivel mount 32 and 34 , respectively, with which it is detachably attached to a helmet. Four electrodes 36 , 38 , 40 and 42 of the corona treatment device are arranged in a stationary manner (only two electrodes 36 , 38 can be seen in the top view of FIG. 3). The four electrodes 36 , 38 , 40 and 42 are, as can be seen in FIG. 4, offset from one another in such a way that the corona discharges they emit on the visor 30 sweep over the entire inner surface of the visor when it is about a central axis Z ( Fig. 3) is pivoted around; the necessary clamp for the visor and its rotary drive are not shown.

For the corona treatment, the visor 30 is rotated in the direction of arrow A ( FIG. 3) about the axis Z, for the purpose shown at a rotation frequency of 2 / min; after two full turns, the corona treatment for a visor is already finished.

The distance between the electrodes 36 , 38 , 40 and 42 from the visor 30 is 6 +/- 2 mm, the electrode voltage 7 kV. Then the visor 30 is unclamped and the next visor 30 is clamped. Of course, it is also possible to treat several visors at about the same time by appropriate design of the visor holder, the size and arrangement of the electrodes, etc.

The next step in the production process is to apply the anti-fog layer ( 18 in FIGS. 1, 2). In this case, an application is first carried out by flooding with a suitable anti-fogging material such that the flooding begins below the upper edge of the substrate 10 or the scratch-resistant layer 16 in FIG. 1, so that an upper edge R2 remains free at the top, ie not is covered with the anti-fog coating varnish. The anti-fog coating lacquer forms a corresponding layer which extends to the lower edge of the substrate 10 or the scratch-resistant layer 16 in FIG. 1. The edge R1 on the lower edge in FIG. 1 is therefore not present at this stage.

As soon as a sufficient batch (for example 30 pieces) of visors 30 has been coated with the anti-fog coating lacquer in this way, the lower edge R1 is now formed; in this area the anti-fog coating is now removed again. For this purpose, the entire batch of visors (this would of course also be possible for each visor individually), with the same orientation of the visors, is partly inserted into a flat trough so that the lower edge of the visors are all immersed in a solvent for the anti-fog coating lacquer how the lower edge R1 to be formed is wide, ie by the dimension "h" shown in FIG. 1. The easiest way to do this is to set a liquid level "h" of the solvent in the tub, and the visors 30 are placed on the bottom of the tub. Preferably a water soluble anti-fog coating material is used and the solvent used in the tub is then distilled water. For the removal of the edge layer R1 by the solvent, the solvent should rest, ie not flow, in order to obtain a clearly defined tear-off edge of the anti-fog layer 18 at the transition to the edge R1 which is released.

When the batch of about 30 sights has stood in the still and distilled water for about 15 minutes, the process of forming the edge R1 has ended. In the area of the edge R1, any anti-fogging material is removed without leaving any residue, so that the anti-fogging coating now has the shape shown in FIG. 1, that is, it extends only up to the upper edge R2 and below only to the lower edge R1 . In the area of the two edges R1, R2, the visor later bears on sealing beads in the case of a visor built into a helmet. In the case of a visor according to the invention, the sealing beads therefore only act on the resistant, scratch-resistant layer 16 , but not, as has hitherto been the case in the prior art, on the relatively “soft”, ie wear-prone anti-coating coating 18 . Their lifespan is therefore significantly increased.

Those necessary to practice the present invention Materials are known. For the scratch-resistant coating can for example by the applicant for substrates PC or PMMA is a coating system based on polysiloxane which are sold under the name "PRoLAC" becomes. The binder base of "PRoLAC" is methyltrimethoxi lan. To improve adhesion on substrates such as PC or CR39, suitable primers can be used if necessary will.

Suitable photochromic materials are, for example, in Polymers Paint Color Journal, Volume 181, No. 4238, May 29 1991, pp. 296-299.

A z. B. suitable for PC or PMMA anti-fog material is registered by the applicant under the name "PRoLAC A / F" expelled; the binder base is PU (polyurethane).

Claims (19)

1. molded part ( 20 ) with a plate-shaped substrate ( 10 ) and an anti-fogging layer ( 18 ), characterized in that the anti-fogging layer ( 18 ) does not extend over an entire surface of the substrate ( 10 ) , so that a lower edge (R1) remains free. 2. Molding according to claim 1, characterized in that the substrate consists of inorganic (silicate) glass. 3. Molding according to claim 1, characterized in that the substrate ( 10 ) consists of organic glass, preferably made of polycarbonate (PC), and at least on one of its surfaces with a scratch-resistant coating ( 14 , 16 ) is preferably made of polysiloxane. 4. Molding according to at least one of claims 1 to 3, characterized in that the substrate ( 10 ) is provided on one of its surfaces with a photochromic zone ( 12 ), the transparency and / or color tone of which depends on the irradiation with ultraviolet Radiation changes. 5. Molding according to at least one of claims 1 to 4, characterized in that a substantially to the lower edge (R1) parallel upper edge (R2) is provided, which is not covered by the anti-fog layer ( 18 ). 6. Molding according to at least one of claims 1 to 5, characterized in that the molding is designed as a helmet visor, which has a substrate made of organic glass ( 10 ), the front surface of which is provided with a photochromic zone ( 12 ) that the zone ( 12 ) is completely covered with a scratch-resistant layer ( 16 ) made of polysiloxane, that the rear surface of the substrate ( 10 ) is covered over the entire surface with a scratch-resistant layer ( 16 ) made of polysiloxane, and that the rear scratch-resistant layer ( 16 ) is in its central Section is provided with an anti-fog layer ( 18 ), a lower edge (R1) not being covered by the anti-fog layer ( 18 ). 7. A method for producing a plate-shaped molded part according to at least one of the preceding claims, characterized by the following steps:

• a) provision of a substrate ( 10 )
• b) treatment of the substrate ( 10 ) with a corona discharge; and
• c) Applying an anti-fogging layer ( 18 ) to the surface of the substrate prepared by the corona discharge.

8. The method according to claim 7, characterized in that a substrate ( 10 ) made of an organic glass, preferably as polycarbonate, is used, on which a scratch-resistant coating ( 16 ) is preferably applied from polysiloxane, which are then subjected to the corona treatment becomes. 9. The method according to claim 7 or 8, characterized in that the corona treatment at a tension of the corona treatment facility of 7 kV and a distance of Corona treatment device from the surface of the Substrate or the scratch-resistant coating attached to it 6 +/- 2 mm. 10. The method according to claim 9, characterized in that a relative movement of the surface to be treated and essentially along the corona treatment device of the area is carried out, the area being twice per minute of corona discharge. 11. The method according to at least one of claims 7 to 10, characterized in that the substrate ( 10 ) is flooded with a photochromic material, sprayed or immersed therein, and then the substrate with the photochromic material is subjected to a heat treatment, to form the photochromic zone ( 12 ). 12. The method according to claim 11, characterized in that the substrate ( 10 ) consists of polycarbonate and the heat treatment at 80-130 ° C, preferably 120 ° C, takes place over a period of about 30 min. 13. The method according to at least one of claims 8 to 12, characterized in that the substrate ( 10 ) is coated on both sides by dipping with a scratch-resistant layer ( 14 , 16 ) made of polysiloxane. 14. The method according to claim 13, characterized in that after coating with polysiloxane a heat treatment is carried out, preferably at 120 ° C for 120 min.   15. The method according to at least one of claims 7 to 14, characterized in that the anti-fogging layer ( 18 ) is first applied over the entire surface to the surface prepared by the corona treatment and then for the formation of the anti-fogging Layer ( 18 ) free lower edge (R1) is partially removed from the surface or layer ( 16 ) lying under the anti-fog layer ( 18 ). 16. The method according to claim 15, characterized in that the entire surface provided with the anti-fog layer ( 18 ) molded part ( 20 ) is used in a tub in which there is a solvent for the anti-fog layer with a solvent level , which corresponds to the height of the lower edge (R1). 17. The method according to claim 17, characterized in that that the material of the anti-fog layer is water soluble and that the solvent is distilled water is. 18. The method according to claim 17, characterized in that the molded part ( 20 ) to the depth of the lower edge (R1) is immersed in the solvent for about 15 min. 19. The method according to at least one of claims 7 to 18, characterized in that the application of the anti-fogging layer is carried out by dipping or flooding so that an upper edge (R2) remains free on the molded part ( 20 ), which is not of the anti-fog layer ( 18 ) is covered.