DE4304488C1 - Prodn. of photochromic plastics moulding useful e.g. for sunglass lens, visor, car window etc. - by impregnating granulate with photochromic dyestuff soln., drying and moulding - Google Patents

Abstract

In the prodn. of a photochromic plastics moulding by thermoplastic processing of a moulding compsn. (I) contg. photochromic substance(s) (II), (I) is prepd. by a) prepg. particulate material (III), esp. a granulate from thermoplastic resin (IV), which forms a transparent moulding; b) prepg. a dyestuff soln. (V) by dissolving (II) in a solvent (VI); c) treating (II) with (V), so that the particle absorb (V); d) drying the (V)-impregnated (III) to remove (VI) and any other volatiles; and e) heating, plasticising and homogenising the prod. to form (I). The prepn. of (I) and thermoplastic processing are carried out at a temp. (T) above the softening temp. of (IV) and below 320 deg.C. Pref. (IV) is PMMA, cellulose acetate polymer or a polycarbonate (IVA), esp. poly(diethylene glycol bis(allyl carbonate) or a bisphenol A polycarbonate. (II) is indoline-spiro-benzopyran, -benzoxazine, -naphthoxazine, -quinoline-oxazine and/or -isoquinoline-oxazine cpd(s). (VI) is an organic solvent (mixt.) which dissolves (II) complete and can dissolve and/or swell (IV). If (IVA) is used, (VI) is cyclohexanone (VIA). USE/ADVANTAGE - (I) is useful for making sunglasses, visors for motor cycle helmets, instrument covers and shields, car windows and sun roofs, light coupling etc. After the 25 h Xe test, carried under standard conditions, the mouldings have a residual power (R; difference in optical density between exposed and unexposed state) of over 30%, esp. over 50% (claimed). The mouldings are optically clear. Homogeneous distribution of (II) is achieved by a simple technique.

Description

The invention relates to a method for producing a photochromic molded body made of plastic by thermoplastic cal processing of a molding compound, the at least one contains photochromic substance. Furthermore concerns the Erfin dung an independently manageable and storable Zwi The product of this process, namely a photochromic Plastic granules containing substance. Finally be meets the invention obtained by the new method lichen photochromic shaped body. The form according to the invention bodies are massed with photochromic substance colors and show compared to conventional, by dipping products obtained have a significantly longer lifespan of the photochromic effect (number of cycles between not exposed / light and exposed / colored state).

The document EP 0 141 407 B1 discloses u. a. various Process for producing a photochromic object, the in a solid, transparent polymeric organic base material a photochromic set of a photochromic  Contains connection. It is said, "the photochromic ver bond can be introduced into the base material by known methods such as dissolving or dispersing the ver binding in the base material, d. H. by contribution (Inbi bation) of the photochromic compound in the base material ". The method of choice is the introduction of the photochromic Connection in the prefabricated body made of basic material rial with the help of dip dyeing or by generating a temporary coating on a molded body surface and on closing thermal diffusion. Here the photo migrates chrome connection at elevated temperature (at for example within a few minutes up to a few Hours at temperatures in the range of 80 to 180 ° C) and penetrates into the near-surface layers of the molded body a. In addition, it should be possible, "the photochromic compound mix with a polymerizable material that after curing, an optically clear polymerizable base supplies material, and the polymerizable so formed The composition then becomes a film, plate or Potted lens, or by injection molding or other Process brought into the form of a plate or lens " The publication does not contain an example of the latter Ways of working. According to the only procedure specified The example is written on a plate made of "CR 39" (Poly-di ethylene glycol bis (allyl carbonate)) a the photochromic ver bond-containing lacquer layer applied, and the Ver binding from this temporary layer at 160 ° C into the upper Diffused layers of the molded body near the surface.

This latter method for photochromic off Armor of an object made of synthetic plastic described in more detail in DE-OS 36 07 759. Thereafter, the introduction of the photochromic compound in the plastic material at a temperature close, however  below the melting temperature of the photochromic compound be worked. Have typical photochromic compounds a melting point between about 120 and 140 ° C.

Similar general information on mixing a photochro connection with an optically clear polymer and processing processing of the composition thus formed by casting driving, injection molding or other processes for a film or lens can also be found in the US patents 4,215,010 or 4,342,668. However, this also applies here only specified process example the dip dyeing, taking a 2 mm thick lens made of "CR 39" into it for 90 min bath kept at 120 ° C from a 4% solution of each some photochromic compound in diethylene glycol is diving.

US Pat. No. 3,551,344 discloses a process for producing a photochromic plastic article, in which a solution of a polyvinyl resin with an effective content of photochromic substance (typically less than 5% by weight) is freeze-dried. The powdery or spongy Lyophilisat is crushed into a powder, and this powder is molded in a suitable shape by compression molding to the desired object, such as a disc, film or the like. For example, the powder is processed under a pressure of about 280 × 10 ⁵ N / m ² and at a temperature of about 138 ° C. by molding.

U.S. Patent 4,889,413 discloses the manufacture of photochromic objects made of polyurethane plastics. The photochromic compound is either with the diisocyanate Component or mixed with the polyol component. The The mixture obtained is mixed with the other necessary one  Component (s) combined to produce polyurethane, and the mixture is polymerized to a polyurethane body to produce that contains a photochromic compound. Ent speaking of the embodiments are mild polymers conditions provided, such as a polymerization in Course of 2 days at 60 ° C. Based on comparative vers It is demonstrated that the procedure does not apply to others Plastics such as poly (triethylene glycol dimethacrylate) or Polyvinyl butyral is transferable.

Furthermore, DE-OS 40 24 330 discloses a method for Production of a photochromic film based on plasticized, partially acetalized polyvinyl alcohol. The photochromic connection and optional Stabilisa gates and / or protective substances are in the partially acetalized polyvinyl alcohol or in the plasticizer mixed in. The maximum temperature in the extruder is 200 ° C; the melt pressure after the melt pumps is 70 bar. The The finished film is extruded into a water bath. The foil is known as an intermediate layer for the Her position of a motor vehicle windshield used.

To the knowledge of the inventors, it is used in operational practice for the production of photochromic molded articles made of plastic in first of all the dip dyeing applied. The prefabricated Plastic body is used in a limited period of time Dye solution immersed at an elevated temperature is held. Solvents are chosen which completely dissolve the photochromic connection, however are inert to the plastic. Exemplary solutions medium are silicone oils or diethylene glycol. The temperature the dye bath can be up to 10 ° C above the enamel point of the photochromic connection; Tempe temperatures above 180 ° C should be avoided (cf.  Document WO 85/02619). Trials with solvents, too dissolving the plastic material were unsuccessful. The dissolved plastic material accumulated in the dye bath and was partly on newly introduced plastic bodies deposited. Surface defects (cloudiness, ver hardening and embrittlement); furthermore the chip The behavior of the parts is adversely affected.

The well-known dip dyeing has a number of basic disadvantages that cannot be remedied.

• - So - even with repeated repetition of the loading action - only a limited amount photochromic Connection introduced into the plastic material become. The differences that can be achieved Transparency in the exposed and the unexposed Condition is often not sufficient.
• - The photochromic compound collects in the upper areas close to the surface. There is a danger there damage caused by subsequent diffusion Oxygen. The usable life is limited, in which a sufficient and reversible change in the Coloring can be achieved. Then also occurs in the Areas near the surface are comparatively high Concentration of photochromic substance, which the plastic properties changed and that after sluggish application of scratch-resistant, anti-fog and other finishing coatings impaired.
• - The "photo" which is already commercially available today chrome systems "often contain in addition to the or the actual photochromic substance (s) further various stabilizers for the matrix material and / or protective substances for the substance. Because of your These stabilizers have a completely different chemical structure  lisators and / or protective substances in the immersion bath another Dissolution, diffusion and migration behavior than that photochromic substance. The achievable concentrations of stabilizers and / or protective substances in the upper shallow layers of the treated plastic body is difficult to predict.
• - After all, immersion coloring only allows a moderate one Yield of the quite expensive photochromic used Connections and proves to be an elaborate Process that must be carefully controlled to reproducibly high quality products create. For relatively small objects with high ones Value creation, such as eyeglass lenses, optical This effort can be tolerated by filters and lenses become. However, it is hardly economically viable after this process, large inexpensive parts, such as such as visors for motorcycle helmets, window panes, Skylights or other large covers to manufacture.

There is therefore still a need for a simple, inexpensive process for the production of photochromic form body made of plastic, in particular of molded articles with comparatively large and irregular in individual cases measurements such as visors for motorcycle and other sports helmets, skylights, car glass roofs, windows, front lens ben and other sheet materials, such as for winter gardens, Greenhouses, telephone booths and the like.

The object of the invention is a simple Ver drive to the production of photochromic moldings from art Specify substance in bulk with photochromic substance are colored and which increase the lifespan of the photo chrome effect (number of cycles between non-exposure temper / bright and exposed / colored state.  

In particular, photochromic plastic bodies of this type be provided, the transparency of which in the non-light condition not less than 70% (transparency of air = 100%), and their transparency when exposed to Sunlight at room temperature quickly by at least 30 per points and more decreases.

According to another object of the invention, a storable complete and independently manageable intermediate product provision of such photochromic plastic bodies be put.

Based on a process for producing a photo chrome molded body made of plastic by thermoplastic Processing a molding compound that has at least one photo contains chrome substance, is the inventive solution to this problem characterized in that to form the molding compound

• - A particulate material, especially a gra nulate from the pre-formed, thermoplastic, a transparent molded plastic is provided;
• - The photochromic substance dissolved in a solvent to obtain a dye solution;
• - The particulate plastic material with this Dye solution is treated, the plastic Particles absorb the dye solution;
• - The plastic particles soaked with dye solution dried to remove the solvent and possibly others largely remove volatile components; and
• - the plastic thus mixed with photochromic substance Particles are heated, plasticized and homogenized to get a molding compound; and  this formation and thermoplastic processing of the mold mass at a temperature above the plastic proof temperature and below 320 ° C.

According to the method of the invention, photochromic Obtained molded plastic. The moldings are optically clear and point throughout the plastic mass - as far as can be determined by simple means - one homogeneous distribution of the photochromic substance (s). To at least with the naked eye, no inhomogeneities of the Dye distribution can be determined.

The reversible photochromism of those generated according to the invention photochromic molded body made of plastic has a long, usable lifespan. This usable lifespan is a multiple of the lifespan of glasses was determined in the layers close to the surface Photochromic substance introduced by means of dip coloring has been. With accelerated aging (25 h xenon test) values were determined that required an intensive wearing time with constant alternating stress of several months he let wait. The inventors suspect that the high life duration of reversible photochromism also on homogeneous Distribution of the photochromic substance (s) within the entire plastic mass is traceable. The bigger part of the photochromic substance (s) is diffused from attack deprived of oxygen. The more outside Dye molecules (near the interface) shield them further inside dye molecules also optically, so that a light-induced "optical" aging only gradually can penetrate the inner areas of the plastic body. At light-induced damage is initially indicated excited molecules mainly into a short-wave absorption species are transformed, and then the so far  non-excited molecules are effective. The invention The method enables one adapted to this behavior Concentration of the dye molecules within the whole Plastic mass.

The method according to the invention allows within the Plastic body the concentration of photochromic sub stamp (s) in a wide range as desired. In the photochromic molded body can easily have a color substance concentration between about 0.05 and 5 wt .-% photo chromic substance can be adjusted.

In the method according to the invention essentially occur no loss of photochromic substance. Typically there is less dye solution on the plastic granules sprayed on when the granules could take up. The whole Dye solution is recycled.

This is preferably done in the method according to the invention Melt the granule mixed with photochromic substance lates to molding compound and thermoplastic processing the molding compound at a temperature between about 200 and 300 ° C. Based on the data available so far, it must be called Surprisingly, typical photochromic sub punch with substituted spiro (indoline) oxacin framework Withstand temperatures up to about 300 ° C without damage. in the Within the scope of the method according to the invention, a molding compound, which contains, for example, 0.2% by weight of photochromic substance, Process thermoplastic into an injection molded body at 300 ° C be highly transparent and reversible photo chromie has. In the context of the invention it is recognized what that at temperatures above 320 ° C the usual used photochromic substances quickly thermal ge be damaged and destroyed. Is the thermoplastic  Processing at 350 ° C, for example, raw materials - a brownish-yellow, completely Preserved opaque shaped body that has no photochromism having.

The method according to the invention enables a fine ver divided and largely uniform distribution (molecular dispers) of the photochromic substance used on the Surface and in the near-surface areas of the granu lat particles. Also through long-term dry mixing of plastic granules and powdery photochromic sub can be punched in a ball mill or the like correspondingly uniform distribution of the photochromic sub do not punch on and in the granules.

Advantageous refinements and developments of the Er invention result from the subclaims.

According to the inventive method, the Production of a photochromic molded body by thermopla processing of a molding compound. The generation of the Molding compound is made by melting and / or plastifi adorn a plastic granulate with the photochromic Substance is added. The thermoplastic processing of the molten plastic mass includes processes like that Extruding, molding, injection molding, spraying press and injection blow molding. The choice of procedure depends on the type and shape of the desired shaped body and depends on the type of plastic matrix material. The production of foils, plates, other layer materials and pro Filing is preferably done by extrusion (extrusion sen). Multi-layer laminates can also be produced where only one or more selected Layer (s) consist of the photochromic matrix. The  Mold casting is used in particular to produce in bulk colored lenses, glasses, glasses and others "CR 39" ophthalmic devices (trade name used for poly (diethylene glycol bis (allyl carbonate)) because this plastic is a special, carefully controlled Cooling down program required.

Spraying is particularly preferred in the context of the invention casting processes and related processes such as spraying press and injection blow molding. The thermal load on the photo molding compound containing chrome substance (s) lasts only one short period of time. The length of stay is typically in the high temperature zone of an injection molding device less less than 10 min, especially less than 4 min. Typically short cycle times can be achieved and thus high Productivity. It is also injection molding technology nik a well known and well established technology for which commercially available injection molding machines and tools are available as well as adapted particularly suitable art fabrics. Offer for processing by injection molding especially polycarbonates, here preferably the MAKROLON varieties distributed by BAYER AG, or those of GENERAL ELECTRIC under the trade name LEXAN ver driven polycarbonates.

Basically are matrix materials for the Invention according to the intended, photochromically equipped mass Moldings suitable for all thermoplastics that thermoplastic according to one of the standing ge let the named process be processed and stable, deliver permanent, transparent, optically clear molded articles. Suitable plastics include the polycarbonates Polymethyl methacrylates (including PLEXIGLAS) and acrylic nitrile-methyl methacrylate copolymers (AMMA), the Cellu  loose acetate polymers including cellulose triacetate, Cellulose acetate propionate and cellulose acetate butyrate, further the polyvinyl polymers such as polyvinyl acetate, polyvinyl alcohol and polyvinyl butyral and their copolymers, and Polystyrene and polystyrene-acrylonitrile copolymers and many other similar thermoplastic materials. Preferably come as matrix materials polycarbonate and polymethyl methacrylates into consideration because they are easy to process are and stable, permanent, transparent and stable Deliver moldings. Belongs to a suitable polycarbonate also the one sold under the trade name "CR 39" Poly (diethylene glycol bis (allyl carbonate)), provided the photo chrome molding compound is processed by molding. Especially The preferred polycarbonates are the polycarbonates of bisphenol A, which is sold under the trade name MAKROLON or LEXAN are available.

Under the short name "Polycarbonate" are supposed to standing especially these polycarbonates of bis phenol A can be understood.

Are well suited and preferably used ins special such polycarbonates, which at temperatures between around 200 and 300 ° C can be processed thermoplastically. Softens the matrix material already at temperatures Lich below 200 ° C, so longer service lives are from cooling of the molded body produced in the injection mold conducive. At temperatures above 300 ° C, especially Thermal damage begins to increase above 320 ° C supply of photochromic substances. Are well suited for for example the MAKROLON types 1158, 2800 and 6870. The MAKROLON-Type 1158 can already thermopla at around 240 ° C be processed stisch.  

The polycarbonates provided here can be seen excellent processing in the injection molding process and deliver color loose, transparent moldings that are highly heat-resistant, dimen sion stable, sterilizable and resistant to water and the most important solvents. In polycarbonate no effective concentrations of free melt occur Carboxylic acids, which are basic centers of the typical could impair photochromic dyes. In poly carbonates will have a long service life (number of cycles between exposed / colored and unexposed / bright state) of typical photochromic substances. In a Polycarbonate matrix is the occurrence, the diffusion and the Lifespan of oxygen and oxygen radicals except neatly small, which damage the dye molecules could. The lower surface hardness compared to PMMA Polycarbonate moldings can be scratched by coating solid paint can be balanced.

The selected matrix material is in particulate form treated with the dye solution. The particulate mate rial should have such dimensions that for a quick Plasticization and homogenization under normal conditions conditions are suitable. Preferably the largest particle dimension should not be more than about 5 mm, otherwise one Heating, plasticization and homogenization in the Auf heat zone of an extruder or an injection molding machine can be reached. Is well suited and preferably turned on Standard granulate with a diameter of about 2 mm is used and a length of about 3 mm. Furthermore, crushed Regenerate can be used.

Photochromic substances for the photochromic finishing of Plastics are known in the professional world and in numerous Chen patents described. Suitable photochromic  Substances are, for example, in the documents below described: U.S. Patent 3,562,172; U.S. Patent 3,578,602; U.S. Patent 4,215,010, U.S. Patent 4,342,668, U.S. Patent 4,637,698, US-PS 4 720 547, EP 0 141 407 B1, EP 0 146 136 A1 or DE-OS 40 24 330. Typically contain those described there The dye molecules contain a substituted indoline spiro pyran backbone or a substituted indoline spiro-oxacin Framework. For example:

Substituted indoline spiro benzopyrans of the following general structural formula,

Substituted indoline spiro benzoxazines of the following general structural formula,

Substituted indoline-spiro-naphthoxazines below the general structural formula

Substituted indoline-spiro-quinoline-oxazines of the general structural formula below

or substituted indoline-spiro-isoquinoline-oxazines of general structural formula below

The following known photochromic substances have been used with great success:
9′-methoxy-3,3-diethyl-1-methyl-spiro (indoline) -2,3 (3H) naphth (2,1-b) (1,4) oxazine color: gray-blue;
9′-methoxy-6-piperidino-1,3,3-trimethyl-spiro (indoline) - 2,3 (3H) -naphth (2,1-b) (1,4) oxazine color: red-violet;
6 ′, 8′-dimethoxy-1,3,3-trimethyl-spiro (indoline-benz- (1,4) oxazine) color: red;
5 ′ - (5′-methyl-2-oxadiazolyl) -1,3,3-trimethyl-spiro (indoline-2,3 (3H) -naphth (2,1-b) (1,4) oxazin) color: green Blue;
3-ethyl-1,3,5,6-tetramethylspiro (indoline-2,3 ′ (3H) -pyrido- (3,2-f) (1,4) benzoxazine) - color: blue;
3-ethyl-1,3,5,6-tetramethylspiro (indoline-2,3 ′ (3H) -pyrido- (3,4-f) (1,4) benzoxazine) color: blue;
5-bromo-spiro (adamantan-2,2 ′ - (2H) benzopyran) color: yellow.

It is also possible to use a mixture of two or more different photochromic substances. As a result, he can target certain, physiologically pleasant color effects. For example, a two-component mixture can be used
5 ′ - (5′-methyl-2-oxadiazolyl) -1,3,3-trimethyl-spiro (indoline-2,3 (3H) -naphth (2,1-b) (1,4) oxazine and
9′-methoxy-6′-piperidino-1,3,3-trimethyl-spiro (indoline-2,3 (3H) -naphth (2,1-b) (1,4-oxazine) color: blue-gray;
a 3-component mixture of the following dyes can also be used:
5-bromo-spiro (bicyclo (2.2.1) heptane-2,2 ′ (2H) benzopyran, 6 ′, 8′-dimethoxy-1,3,3-trimethyl-spiro (indolinbenz (1,4) oxazine) and
3-ethyl-1,3,5,6-tetramethylspiro- (indoline-2,3 '- (3H) pyrido (3,4-f) (1,4) benzoxazine Color: brown.

In the method according to the invention, the selected (s) photochromic substance (s) dissolved in a solvent, that can completely dissolve the substance. Preferential as a solvent is provided with the photochromic substance does not react and in which at least one Dye concentration of 1 to 5 wt .-% can be achieved. Organic solvents such as coal are very suitable hydrogens, alcohols, ketones and ethers; for example can benzene, toluene, ethyl alcohol, ethyl acetate, methyl  ethyl ketone, cyclohexanone, tetrahydrofuran and methyl ether of ethylene glycol. Preferably a organic solvent chosen that not only the photo chrome substance can completely dissolve, but that also does not chemically convert the selected matrix material, but the thermopla serving as the matrix material dissolving, dissolving and / or swelling plastic can Furthermore, the boiling point of the solvent not too high, because the solvent by Ver vaporization largely entirely from the plastic must be removed. Including these claims Solvents such as benzene, toluene, methyl ethyl ketone, cyclo hexanone and solvent mixtures of cyclohexanone and Tetrahydrofuran works well and is preferably a set. In connection with the matrix material polycarbonate particularly good results are achieved with cyclohexanone, which is preferred here.

The concentration of photochromic substance in the color fabric solution can be chosen in a wide range; good ge a concentration of about 0.5 is suitable, for example up to 5% by weight.

At least one can be added to the solution of the photochromic substance Stabilizer for the matrix material and / or a protective substance for the photochromic substance. As a stabilizer In particular, UV absorbers are used for the matrix material about to be considered. Not to excite the dye to impair, the UV absorber should absorb short-wave beers than the maximum absorption of the dye. Before preferably short-wave UV absorbers are provided, whose Absorption does not significantly exceed 330 nm. At for example, certain benzophenone compounds are good is suitable. Such stabilizers can be used in a proportion of  about 0.02 to 2 wt .-% are used, based on the Weight of the plastic granulate. Coming as protective substances especially consider compounds that occur of oxygen radicals, peroxide radicals and / or peroxides prevent in the plastic material. Are well suited here for example certain nickel (II) complexes, which as Singlet oxygen extinguishers or "triplet quenchers" are known. That is, for example, with good success marketed under the trade name "CYASORB UV 1084" n-Butylamine-nickel-2,2-thiobis (4-tert.octylphenolate) has been set. Such protective substances can, for example at a concentration of about 0.02 to 1.0% by weight be based on the weight of the plastic granule lates. Higher concentrations are less appropriate because the nickel complexes themselves are colored and a light green Color the plastic body. More suitable Stabilizers for the matrix material and / or protective substances for the photochromic substance (s) are, for example, in the DE-OS 33 10 388 or specified in DE-OS 40 24 330.

In the process according to the invention, the dye solution is used the photochromic substance (s) and the optional one seen stabilizers and / or protective substances if possible even and fine as well as permanent on and / or in the Distribute plastic granules so that when the Plastic granules in the hopper of an extruder or an injection molding device no separation of dye and Granules are made. Typically, for a uniform Distribution of 0.1 to 10 parts by weight of dye in 1,000 Parts by weight of plastic granules are taken care of. It is one Molecularly disperse distribution of the dye in the plastic granules desirable by dissolving the plastic through the solvent of the dye solution and close the precipitation of the dye when the solution evaporates  is achieved by means. In this way, one can be equal produce moderately colored plastic granulate that at a typical thermoplastic processing (melting zen, plasticizing and homogenizing) a photochromic Shaped body delivers, at least with the naked eye no fluctuations in the intensity of the coloration perceptible are. As below based on a comparison test can be confirmed by mere dry mixing of the Dye powder with the plastic granules such Distribution cannot be achieved. Rather, here occurs in Extruder or injection molding device one hopper renewed separation of dye powder and plastic granulate on and on the injection molded body there are clearly individual color spots to recognize that on isolated dye pigments or dyes material centers are traceable.

If the dye solution is a solvent that dissolves the plastic Contains solvents, must stick, bake and / or prevent any other agglomerate formation of the granules be changed. The dye solution is preferably applied sprays while the plastic granules in a mixing drum or the like is moved vigorously. Furthermore it is expedient, at the same time a strong gas flow through the to blow agitated granules for rapid evaporation of the solvent. Spraying the dye Solution on the plastic granulate can at room temperature be performed. For example, reverse can be used as the gas stream serve exercise air.

The plastic granulate is preferably provided with such Amount of dye solution treated entirely by that Granules can be sucked up. For example 1,000 parts by weight of granules with 20 to 100 parts by weight Treated 2% dye solution. Spraying the paint  cloth solution should be done quickly, preferably at one time range from about 1 to 2 min. While spraying should the granules are moved vigorously; also a gas electricity is blown through the moving granules. Even after the granules should still be sprayed on mixed or stirred vigorously for a while and immediately a gas stream is blown through the moving mix at an early stage become. This treatment can last for about 10 to 40 minutes can be provided. All of these measures are important to ver aggregates from clumped granules avoid, because such aggregates staining inhomogeneities on Injection molded body could cause.

The well-mixed granulate is then dried around solvent residues, moisture and other volatile Remove components as far as possible. Preferably can a two-stage drying process with pre-drying at a lower temperature and a final drying voltage at a higher temperature. Unless as Cyclohexanone is used as solvent Predrying at around 80 ° C and a final drying in a forced air oven or the like at about 120 ° C proven.

A dye con is preferably added to the colored granules concentration of 0.05 to 5 wt .-% photochromic substance posed. If necessary, repeated treatment with Dye solution can be provided to get the desired color adjust substance concentration.

After this impregnation of the granules with dye solution and Drying will get a transparent colored granulate The dye is evenly and permanently on and / or abge in the surface areas of the granules  divorced and distributed. The granules appear homogeneous pourable and can be handled in the same way as that Starting or raw granules before dye treatment, without that a new separation of granules and dye occurs.

That with the photochromic substance (s) and the optionally provided stabilizers and / or protective substances provided plastic granulate represents a valuable intermediate product that is handled as such independently can, for example, stored and for use on a can be transported to another location. The storage and the Transport is conveniently carried out with the exclusion of Moisture in opaque containers.

Often, the granules treated with dye solution become one have higher dye concentration than on the finished one photochromic molded body is desired. In this case it is it is possible to use the dye-containing granules in the sense of a Masterbatch with additional (dye-free) raw granules mix, and this mixture of granules to produce a use molten molding compound. It is still possible to pass this mixture of granules through an extruder and to produce a rod or wire extrudate, which is chopped into granules again. This way a granulate can be produced, the mass with the photochromic substance is colored and that exactly for the thermoplastic further processing into molded articles seen concentration of photochromic substance. Such a granulate, the bulk with photochro mer substance is a valuable intermediate product in the sense of the present invention.  

The added with photochromic substance according to the invention Plastic granules, optionally with additional dye free raw granulate can be mixed, is used for production a molding compound. For this, the material is placed on a Temperature above the softening temperature of the art heated fabric. In addition, there is typically one mechanical action to plasticize the material and homogenize. Within the scope of the invention it is recognized been that the typical photochromic substances with a substituted indoline spiro-oxazine or pyran backbone the formation of the thermoplastic molding compound and thermoplastic processing of the molding compound into shaped bodies are stable up to a temperature of about 320 ° C. These photochromic substances quickly become above 320 ° C thermally destroyed, which is due to an increasing brown color becomes recognizable. The thermoplastic processing takes place at temperatures between 330 and 340 ° C, they contain Moldings an increasing number of brown spots and are cloudy. The thermoplastic processing takes place at 350 ° C, so a yellowish brown, completely opaque form get body. Therefore, when creating the shape mass and in the thermoplastic processing of the mold particularly high pressures are avoided, the shear result in stresses on the material could heat a temperature above 320 ° C.

Preferably, the molding compound and the thermoplastic processing of the molding compound at a tem temperature between 200 and 300 ° C. This temperature range is especially for the thermoplastic processing of Polycarbonates (here in particular polycarbonate esters of Bisphenol A) well suited. It is particularly preferred for Temperatures between about 225 and 265 ° C worked; here MAKROLON grades 2400, 6870, 1158,  3100, 1143, 2403 JR, LQ 2643, LQ 2647, LQ 2645, AL 2443, AL 2447, AL 2643, AL 2647 can be used.

It is convenient to put it in the hopper of an extruder or an injection molding device introduced dye-containing Process granulate quickly. Preferably the duration the high temperature load is only a few minutes and do not exceed a period of 10 minutes. In Ver During this thermoplastic treatment, the photo chrome (n) substance (s) and the optional sta bilisators and / or protective substances homogeneous in the molding compound distributed so that a molded body colored in the mass is obtained. The thermoplastic is preferably used Processing of the molding compound by extrusion or Injection molding. The injection molding process is particularly before moves because here quickly and in a single step the finished molded body is obtained. For polycarbonates a longer cooling phase within the injection mold is not required. There can be high shot weights and cycle times be achieved. Typical injection molded bodies are, for example white glasses, visors for motorcycle helmets, instruments coverings and panels, car windows and glass roofs, Skylights and the like.

A Nachbe can on the molded body produced according to the invention act. For example, a scratch hard coating or an anti-fog coating ("anti fog ") can be applied or other product ver finishes are carried out. A scratch-resistant coating is particularly recommended for moldings made of polycarbonate value. Such a coating also makes diffusion difficult oxygenation. Such coatings can be on the moldings produced according to the invention without problems be brought in because there are no atypical compositions in the layers near the surface.  

The following examples and comparative experiments serve to further explain the invention.

Comparative experiment 1

1 kg polycarbonate granulate (MAKROLON grade 1158, essentially cylindrical particles with a diameter of about 2 mm and a length of about 3 mm) is in a given cylindrical mixing drum, which on the inner circumference of the Cylinder wall inclined ribs for a strong mix of the goods. In the rotating mixing drum 2.4 g of dye powder are introduced. As a dye 1-methyl-3,3-diethyl-spiro (indolino-9′-methoxy-2,3 ′ (3H) naphth (2.1-6) (1.4) oxazin) used (slightly yellowish Crystals, melting point 138 ° C, compare for the production EP 0 146 135 A1, example 1). The crystalline material is in a mortar for 10 minutes before use Powder has been triturated. The mix is at for 30 minutes treated about 100 rpm within the mixing drum. On the mix is then removed and immediately placed in the Filling funnel of an injection molding machine introduced (model A 320/200 from Aburg, Losberg; this is a screw injection molding machine with a screw through knife of 22 mm and with a screw length of 400 mm; the locking force is 25 t).

As an injection molded body, a structure of two is typically ge curved glasses (2.4 mm thick) are connected to one another via sprue bars. The structure has a shot weight of 22 g, and the injection molding machine produces three shots per minute. The processing the molding compound takes place at temperatures between approximately 200 ° C. (Feed zone) and about 260 ° C (nozzle temperature). The Ver  duration of the plastic mass in this high temperature zone is less than 5 min.

The lenses obtained are basically gray-green colored. The coloring is not homogeneous. It is clear to recognize individual color dots or colored spots that traceable to individual, undissolved dye pigments are. The product is not for use as eyeglass lenses suitable.

example 1

In 1 liter of cyclohexanone (purum, bp 154-156 ° C) are under Stir and shake 20 g 1-methyl-3,3-diethyl-spiro (indo lin-9'-methoxy-2,3 '(3H) naphth (2.1-6) (1.4) oxazine) dissolved. Of the Dye dissolves completely and you get a deep one blue dye solution.

It becomes a rotating mixing drum with a cylindrical um Side wall and flat end faces provided. The Fas is about 25 kg of granules. On the inner circumference the peripheral wall are inclined ribs for vigorous mixing of the mix. The two foreheads surfaces have a number of holes and it is one Enclosure provided so that a strong air flow through the moving mix can be blown.

10 kg of polycarbonate granules are placed in the mixing drum (MAKROLON grade 1158, cylindrical particles with a Diameter of about 2 mm and a length of about 3 mm) filled. The drum is rotated at about 100 rpm. In the rotating drum becomes 600 ml in the course of 1 min Sprayed dye solution. Immediately after completion of the Adding the dye solution causes a powerful gas flow  the moving mix is blown (ambient air of approx. 23 ° C, Flow approx. 20 l / min). With continued air flow the drum is rotated for 15 minutes. Then it will Mix taken out, on a sheet to a thin layer spread and dried at 80 ° C for 2 h. After that is the granules can be stored.

It becomes a crystal clear, light blue colored, free-flowing Receive granules that only agglomerate to a minor extent merate from 2, 3 or more caked pellets contains items.

Before thermoplastic processing, for example in one Injection molding machine or in an extruder is done in the usual way Way another drying. For example, this is done placed material in a forced air oven and added for 2 hours Dried 120 ° C. The granulate is then ready for use.

200 g of ready-to-use, colored granules are made with 1 kg ready-to-use raw or raw granulate mixed. The Granulate mixture is injection molded into the hopper machine filled (model A 320/200 from Aburg, lot Castle; this is a screw injection molding machine with a screw diameter of 22 mm and with a screw length of 400 mm; the locking force is 25 t.

The molding compound is thermoplastic processed at Temperatures between 200 ° C (feed zone) and 250 ° C (nozzles temperature). The dwell time in the high temperature zone be wears about 4 minutes.

The molding compound is at an injection pressure of less than 150 bar, in particular at about 120 bar in an injection mold  splashes. The gate diameter is approximately 0.5 to 1.0 mm. It is made up of two typically curved glasses glasses (layer thickness 2.4 mm) created by two sprue webs are interconnected. The shot weight of the Ge image is 22 g; 3 rounds per minute are generated.

The lenses are completely homogeneously colored gray-green. The optical and photochromatic properties of glasses len glasses are measured under normal test conditions. The results obtained are in the table below listed.

Example 2

Essentially, the process according to Example 1 is repeated get. Deviating for the generation of the dye solution in 1 liter of cyclohexanone 20 g 1,3,3-trimethyl spiro (indolino- 6′-piperidino-9′-methoxy-2,3 (3H) naphth (2.1-6) (1.4) oxazine) solved. The dye dissolves completely and you get a red-violet dye solution.

This dye solution turns light violet Preserved glasses. The optical and photochromatic Properties of the glasses are measured. The results nisse are listed in the table below.

Example 3

Essentially, the process according to Example 1 is repeated get. The MAKROLON- Type 3100, (cylindrical particles with a single pass knife of about 2 mm and a length of about 3 mm) puts. The plasticization of the colored granules and the thermoplastic processing of the molding compound takes place in the  same injection molding machine at temperatures between 260 ° C (Feed zone) and 300 ° C (nozzle temperature). It will be homo Preserved, gray-green colored glasses. There are no signs of thermal damage to the paint fabric noticeable.

Comparative experiment 2

The procedure according to Example 3 is essentially repeated get. The colored plastic is deviated Granules (MAKROLON 3100) and the thermoplastic process processing of the molding compound in the same injection molding machine Temperatures between 280 ° C (feed zone) and 330 ° C (nozzles temperature. The residence time of the molding compound in the high temperature temperature zone is less than 4 min. It turns gray-green preserved colored glasses. The glasses are cloudy. With The naked eye can see brown spots that are there mixed damaged dye are traceable.

Comparative experiment 3

The procedure according to Example 3 is essentially repeated get. The plastification and thermopla differ processing of the molding compound in the same spray casting machine at temperatures between 290 ° C (feed zone) and 350 ° C (nozzle temperature). The residence time of the molding compound in the high temperature zone is less than 4 min. That he holding structure from two glasses and two verb dungsstegen consists of a yellowish brown, completely opaque mass that shows no photochromism.

Example 4

The procedure according to Example 2 is essentially repeated get. 2 kg of colored granules are mixed with 10 kg of raw granules  (MAKROLON 1158) mixed. The granulate is different mix in the hopper of an extruder (laboratory extruder of the Koch, Munich; this is a Schnek kenextruder with a round die head that has 12 holes points) filled. The thermoplasticization of the granules and the thermoplastic processing of the molding compound takes place at approx. 280 ° C. Through the nozzle head, wires with a Extruded diameter of 2 mm. The extruded wires are cooled in a water bath, then chopped and dried. It turns a pinkish red in the crowd obtained colored granules. The granules are dense, un transparent cans stored and can then be given Time to be processed into photochromic injection molded articles.

On the glasses obtained according to Examples 1 and 2 (gray-green or reddish colored poly in the mass carbonate, layer thickness 2.4 mm) according to standard conditions conditions (kinetic measurements according to DIN 58 217) determines:

T _o = output transmission at Vλ in the brightened, unexposed state;
T _s = transmission after irradiation with 60 klux at 23 ° C for 15 min;
ΔOD = difference in optical densities between exposed and unexposed states;
HWZ = time required to brighten by half the darkening (ie HWW = brightening time to T = 1/2 (T _o + T _s );
R = residual power in ΔOD after x hours of xenon test (under standard conditions at 23 ° C).

Table I

Table II

It is from the test results shown above Obviously that according to the inventive method photo chrome injection molded polycarbonate bodies are available that approximately the same power ΔOD and the same darkening and lightening behavior show, like the well-known, by immersion coloring available products. However, the fiction according to the form produced and equipped with photochromic mass have a much higher life expectancy. A 25 hour test duration in the Xenon test can be with an intensive Wearing time of about 7 to 8 months can be equated.

Claims (26)

1. A process for producing a photochromic molded body made of plastic by thermoplastic processing of a molding composition which contains at least one photochromic substance, characterized in that for forming the molding composition

• - A particulate material, in particular a granulate from the pre-formed, thermoplastic, a transparent molded body forming plastic is provided;
• - The photochromic substance is dissolved in a solvent, whereby a dye solution is obtained;
• - The particulate plastic material is treated with this dye solution, the plastic particles absorb the dye solution;
• - The plastic particles soaked with dye solution are dried in order to largely remove the solvent and possibly other volatile constituents; and
• - The thus mixed with photochromic substance plastic particles are heated, plasticized and homogenized to obtain a molding compound; and this formation and thermoplastic processing of the molding composition takes place at a temperature above the plastic softening temperature and below 320 ° C.

2. The method according to claim 1, characterized in that the thermoplastic processing of the molding compound at a Temperature between 200 and 300 ° C takes place. 3. The method according to claim 1 or 2, characterized in that the thermoplastic processing of the molding compound Extrusion, molding, injection molding, injection molding or Injection blowing takes place. 4. The method according to claim 3, characterized in that the thermoplastic processing of the molding compound Injection molding is done. 5. The method according to any one of claims 1 to 4, characterized in that a polymethyl methacrylic as thermoplastic lat, a cellulose acetate polymer or a polycarbo nat is used. 6. The method according to any one of claims 1 to 3, characterized in that a poly (diethylene gly kolbis (allyl carbonate)) is used, and the thermoplastic processing of the molding compound Mold casting takes place.   7. The method according to any one of claims 1 to 4, characterized in that
a polycarbonate, namely a polycarbonate of bisphenol A, is used as the thermoplastic; and
The thermoplastic processing of the molding compound is carried out by injection molding. 8. The method according to any one of claims 1 to 7, characterized in that as a photochromic substance one or more substit ized compounds from the group of indoline spiro benzpyrane, the indoline spiro-benzoxazine, the indoline spiro-naphthoxazine, the indoline-spiro-quinoline-oxazine or indoline-spiro-isoquinoline-oxazine is used. 9. The method according to any one of claims 1 to 8, characterized in that as a solvent to form the dye solution organic solvent or solvent mixture is used that the photochromic substance (s) is able to solve completely and that the thermoplastic to dissolve, dissolve and / or swell plastic can 10. The method according to claim 9, characterized in that in the case of polycarbonate as thermoplastic art Is used as a solvent cyclohexanone. 11. The method according to claim 9 or 10, characterized in that the dye solution on the plastic particles is sprayed while the plastic particles are moving become.   12. The method according to claim 11, characterized in that at the same time a gas flow through the moving art material particles is blown. 13. The method according to any one of claims 9 to 12, characterized in that the plastic particles with such an amount of color fabric solution to be treated entirely by the Plastic particles is picked up. 14. The method according to any one of claims 1 to 13, characterized in that the dye solution additionally with at least one Stabilizer for the thermoplastic and / or with at least one protective substance for the photo chrome substance (s) is added. 15. The method according to claim 14, characterized in that a UV absorber is used as a stabilizer absorbed more short-wave than the maximum absorption the photochromic substance. 16. The method according to claim 14, characterized in that a compound is used as protective substance, which the occurrence of oxygen radicals, peroxide radicals and / or peroxides in the thermoplastic Reduce. 17. The method according to any one of claims 1 to 16, characterized in that the plastic particles soaked in dye solution  For 1 to 5 hours at a temperature of 80 to 140 ° C to be dried. 18. The method according to claim 17, characterized in that
a multi-stage drying treatment, in particular a two-stage drying treatment is carried out; and
a final drying treatment is carried out immediately before the thermoplastic processing of the plastic particles provided with the photochromic substance. 19. The method according to any one of claims 1 to 18, characterized in that the plastic with the photochromic substance Particles in the sense of a master batch with others not treated plastic particles or raw granules of same type of plastic and so he holding mixture of thermoplastic processing too to be led. 20. intermediate product, namely particulate material, especially granu lat from preformed, thermoplastic, a trans Parent molding plastic characterized in that the plastic particles according to the measures that are specified in one of claims 1 to 19, with one or more photochromic substance (s) and choice wise with at least one stabilizer for art substance and / or with at least one protective substance for the photochromic substance (s) have been added.   21. Intermediate product according to claim 20, characterized in that the plastic particles on the particle surface and / or a photo in the areas near the surface have chrome substance that is in finely divided form, is present in particular in molecularly disperse form. 22. Intermediate product according to claim 20, characterized in that the plastic particles after treatment with the paint fabric solution and drying and optional mixing with further raw granules have been extruded again and then in the mass with photochromic substance are colored. 23. Photochromic molded body made of plastic, characterized in that the shaped body is obtainable by a process which is specified in one of claims 1 to 19. 24. The photochromic shaped body as claimed in claim 23, marked by an injection molded polycarbonate body that is in bulk is colored with photochromic substance. 25. The photochromic molded body according to claim 23, characterized in that the molded body consists essentially of poly (diethylene glycol bis (allyl carbonate)), produced by molding and colored in the mass with photochromic substance is. 26. Photochromic molded article according to one of claims 22 up to 24  characterized in that the molded body after the under normal conditions 25-hour xenon test performed a residual power "R" has greater than 30%, in particular greater than 50%.