DE4031563A1 - Cleaning optical components using non-halogenated solvents - by passing through successive baths contg. organic solvent, water contg. surfactant, and organic solvent for drying - Google Patents

Abstract

Process comprises treating them in a number of successive solvent treatment baths comprising (a) a precleaning stage in baths contg. non-toxic halogen-free organic solvents selected from (cyclo)aliphatic hydrocarbons, terpenes, terpenoids, aromatic hydrocarbons, alcohols, ketones, esters, ethers, glycol ethers, ketals, acetals, N-contg. hydrocarbon cpds. or their mixts. with a b.pt. of over 120 deg.C, whereby the solvent may be miscible with water and dissolves polar and non-polar contaminants; (B) a subsequent washing stage in which the components are washed in water contg. surfactants and (C) a subsequent drying stage in which the components are treated in with one or more non-toxic halogen-free organic solvents chosen from (cyclo)aliphatic hydrocarbons, alcohols, ketones, esters, ethers, acetals and ketals or their mixts. with a b.pt. of below 100 deg.C and an evapn. number of greater than 2. USE/ADVANTAGE - Process gives good residue-free cleaning and drying of optical components without using halogenated hydrocarbons, so that it is environmentally friendly; low energy consumption and economical recycling of the solvents used.

Description

The invention relates to a method and an apparatus for cleaning optical components.

So far, optical components have been on an industrial scale mainly with the help of halogenated hydrocarbons cleans or dries, and that in cleaning systems consist of several successive baths into which the baskets with the parts have been immersed. The drying was generally carried out as so-called steam drying in the vapor phase, with the halogenated hydrocarbon evaporates without residue from the glass surface.

Halogenated hydrocarbons were also partially Solvents used in the entry baths and with combined aqueous baths.

However, halogenated hydrocarbons are a major environmental burden and there has been no shortage of attempts to get these solvents in to replace the cleaning processes.

For example, it is known in the drying stage so-called DI water (double deionized water) to use and the components after pulling them out this ultrapure water bath in a warm air stream or by means of Drying radiation. However, this drying process is relatively energy consuming and requires a lot of effort, when clean glass surfaces are required ready for occupancy.

It has also been proposed to use optical elements in to clean a sequence of exclusively aqueous baths, with a final drying stage using DI Water as described above. With such, pure  aqueous processes, however, can only look like insensitive e.g. B. glasses are cleaned. In addition, can not remove all impurities. For example, that fails Procedure when a wide variety of optical aids such. B. Putties, varnishes or adhesives in one go from the optics parts must be removed.

It is the object of the present invention a method to specify the cleaning of optical components, the without Halogenated hydrocarbons get along, and still good Delivers cleaning results with low energy consumption.

This object is achieved by what is stated in claim 1 Procedure solved.

The inventive method is due to the combination the organic pre-cleaning with an aqueous cleaning very flexible with regard to the degree of pollution and the Type of contamination and provides very good cleaning results, up to optics ready for occupancy.

It is also energy-saving in the drying stage and comes with a minimum of procedural steps, which also makes it is suitable for smaller car washes and is easy to use can be.

By not using halogenated hydrocarbons, it is extremely environmentally friendly and enables economical Recycling of the solvents used.

Because the components from the last bath of dry levels are pulled out at a defined speed, the solvent film runs off without residue and you get a clean, residue-free even without high energy input Surface.  

As an organic solvent in pre-cleaning is before preferably butyl diglycol used. This substance delivers good Cleaning results with the Ver Types of dirt, is miscible with water, so that no Solubilizer in the transition to aqueous cleaning level is required and has a sufficiently high level Boiling point of 230 ° C, so that even with hot baths in the Pre-cleaning can be done. It is still useful if the bathrooms only one de Finished chemical compound contain, so no solution there are medium mixtures within the baths, so that recycling is economically possible by distillation.

In the drying stage, ethanol or acetone are preferred used as a monochemical in the baths. These substances are Low boilers and therefore evaporate without much energy wall, but also evaporate due to their evaporation number, which is greater than 2, not too quickly. Evaporation too quickly would have caused condensation to form on the parts to be dried Consequence due to the evaporative cold of the solvent.

In the aqueous cleaning stage, they are useful alternately used baths that contain surfactants, and pure Rinsing baths in which the surfactants are free of residues optical components are washed off.

It is also useful to start the optical parts Drying level of a draining liquid (dewatering Fluid) to the service life of the subsequent organic solvent bath to increase.

The device for performing the invention The method is characterized in that the tubs at least one of the three cleaning stages at least are partially cased together. The piping enables the contents of the tubs to be pumped around with the  Solvent against the transport direction of the to be cleaned Divide on the principle of countercurrent cascade, so that the Optical parts e.g. B. after going through the pre-cleaning always in a fresh bath free of impurities. The Cascade content can continuously z. B. by filtration cleaned and by adding fresh solvent be supplemented. This represents an alternative to operating the Plant with standing baths, which are in regular intervals must be replaced and towards the end of the service life possibly an insufficient cleaning deliver results.

It is convenient to have at least some of the tubs in the Pre-cleaning stage and the aqueous cleaning stage with Equip ultrasonic sensors, for example on the ground and are attached to the side of the tubs. Farther It is advisable to place heating or cooling devices on the tubs connect to a cleaning at predetermined Temperatures, for example with heated solvent enable.

The system is particularly advantageously designed so that the Tubs of the three stages A: organic pre-cleaning, B: aqueous Cleaning and C: drying each have their own Transport device is assigned. This allows one achieve high cycle times of the system.

It is also expedient if the transport devices for the optical components to be cleaned, the Ultra sound generator, the heating and cooling devices and given if the shut-off valves and pumps for the piping of the Tubs are connected together to a control system, so that the parameters temperature, sound intensity, sound duration, just like the order of the baths, the cycle time of the ge entire system, the service life of the baths etc. is program-controlled adjusted and thus to the different optical parts  of which the cleaning system can be adapted is going through. This way, by together setting the appropriate parameter programs be used for optical parts of different materials are optimized or the different degree of pollution or are adapted to the type of contamination of the optical parts.

For certain tasks it may be useful to do the cleaning parts after pre-cleaning for example for an inspection from the cleaning system to discharge, to skip the aqueous cleaning stage or only with the aqueous cleaning step begin, or inspected parts in the aqueous Reintroduce the cleaning level. So that's a high one System flexibility guaranteed. This is achieved through a U-shaped structure of the three stages of pre-cleaning, aqueous cleaning and drying, the tubs of organic pre-cleaning and the tubs of the drying stage are arranged one behind the other on the legs of a U. The U-shaped structure of the system is also for the operator staff cheap in terms of short distances.

On the other hand, the flexible modular design also allows one optimal adaptation to given spatial conditions, e.g. B. by placing it in an L-shape or in a row.

Further advantages of the invention result from the following description of two exemplary embodiments with reference to FIGS. 1 and 2 of the accompanying drawings.

Fig. 1 is a simplified schematic diagram in which the entire cleaning device is shown in supervision Darge;

Fig. 2 shows the part of the device designated A in side view.

The cleaning system shown in Fig. 1 has a U-shaped structure, the troughs provided there with the reference numerals ( 1 to 15 ) for receiving cleaning or drying liquids are arranged one behind the other following the legs of the U. The area labeled A with the tubs ( 1-5 ) represents the so-called organic pre-cleaning, the area labeled B with the tubs ( 6-9 ) represents the aqueous cleaning stage and the area labeled C with the tubs ( 10 -15 ) the so-called drying level. This does not rule out that e.g. B. the tub ( 10 ) at the entrance of the drying stage is filled with ultrapure water.

Before the tubs ( 1-5 ) of the organic pre-cleaning stage in the area (D) designated parking spaces ( 21 , 22 , 23 ) for the baskets with the optical parts to be cleaned are arranged. The baskets delivered there are lifted by a transport system there and inserted one after the other into the solvent-filled trays ( 1-5 ) of the organic pre-cleaning. The transport system consists of a lift truck ( 25 a) with a height-adjustable gripping arm ( 26 a) for the baskets to be moved, as indicated by the arrow, along the leg in the area of organic pre-cleaning A.

In the area of the aqueous cleaning stage B, a further lifting carriage ( 25 b) is arranged to be movable along the base of the U, as indicated by the arrow. The range of motion of this lifting carriage ( 25 b) overlaps with that of the lifting carriage ( 25 a) in area A of the legs of the U, so it can remove the baskets from the last bath ( 5 ) of organic pre-cleaning and also the first bath in Area of drying level C, use bath number ( 10 ).

Correspondingly, a third lifting carriage ( 25 c), which can be moved along this U-leg, is arranged in area C, which operates drying stage C and ultimately places the baskets with the optical components to be cleaned on a conveyor belt ( 31 ).

All tubs ( 1-15 ) are provided with heating devices and cooling devices in order to be able to adjust the solvent or detergent contained therein to different temperatures. In addition, the tubs ( 1-4 ) of the organic cleaning and the tubs ( 6 ) and ( 8 ) in the aqueous cleaning stage are equipped with ultrasonic sensors ( 27 a-f). The tubs ( 6 ) and ( 8 ) are cleaning baths which contain water with cleaning additives such as e.g. B. contain surfactants or phosphates. In contrast, the tubs ( 7 ) and ( 9 ) rinsing tubs and contain rinsing devices for flooding rinsing or showers that are fed by fresh water. The tubs ( 7 ) and ( 9 ) are therefore not standing baths.

The drying area C is located in the area of a box with a laminar gas flow, since low-boiling organic solvents are used there. In addition, the system is provided with an edge extraction system ( 28 a and 28 b) at the level of the tub edges, which can also be used separately in the three areas A, B and C if required. The odor nuisance for the operating personnel is thus kept low and compliance with the safety regulations is guaranteed.

Due to the media used, the elements of the system are designed in explosion-proof construction.

Optical parts can be found in the cleaning system described below complete absence of halogenated hydrocarbons up to surfaces ready for occupancy are cleaned. To this To achieve the result are the following described process steps carried out and the there mentioned solvents or cleaning fluids or corresponding equivalent substances or those with a similar effect  Fabrics used:

Procedure 1

In the organic pre-cleaning stage A, the baskets with the parts to be cleaned that are delivered to one of the storage positions ( 21-23 ) pass through three baths, for example baths ( 3 ), ( 4 ) and ( 5 ), which are filled with butyl diglycol. They stay in the baths for about 60 seconds or longer, depending on the intensity of the ultrasound amplitude generated there by the generators ( 27 c, d, e). The temperature of the baths ( 3-5 ) is kept in the range between 100 ° C and 60 ° C and the butyl diglycol in the baths is constantly renewed by a circulation filtration. Subsequently, the parts to be cleaned are lifted out by the transport device ( 25 b) from the last bath ( 5 ) before the organic cleaning and the four baths ( 6 ) to ( 9 ) are exposed to the aqueous cleaning stage. Here they go through a bath ( 6 ) with hot water, the Reinigerzu sets such. B. contains the industrial cleaner available under the trade name P3-almeco, a warm rinsing bath ( 7 ) with city water that is continuously flushed through, another hot water bath with surfactants and finally a warm rinsing bath with flowing city water that is continuously renewed ( 9 ) . In the cleaning baths ( 6 ) and ( 8 ) the optical parts to be cleaned are again exposed to ultrasound and additionally the baskets with the optical parts are pivoted in the baths with the aid of oscillator frames not shown in the figure.

When lifting out of the last rinsing bath ( 9 ) of the aqueous pre-cleaning B, the parts still go through a shower and are then freed from the last washing-up liquid residues by the transport device into a pool ( 10 ) filled with ultrapure water and prepared for the drying process.

You are then led by the third transport car ( 25 c) from the DI water bath ( 10 ) in succession through five baths with ethanol, the first bath ( 11 ) being a standing bath and the baths ( 12-14 ) again being cased and there the ethanol is pumped in countercurrent to the direction of transport of the optical parts.

The last bath ( 15 ) is filled with hot ethanol and the optical parts to be cleaned are pulled out of this bath at a defined speed. The ethanol film runs essentially completely. The parts cleaned in this way are then fed via the conveyor belt to the removal positions for testing or further processing (allocation) of the parts. Parts that do not require aqueous cleaning or that must not be exposed to aqueous baths due to the water sensitivity of the optical material can be taken directly from the last bath ( 5 ) of the organic pre-cleaning A into the drying area C by the second transport device ( 25 b). Here, the DI water bath ( 10 ) is replaced, for example, by a further ethanol bath.

It is also possible to discharge the baskets with the optical parts from the cleaning system in the area of organic pre-cleaning A after leaving the bath ( 5 ), for example for a control process. It is also possible to inject parts at this point that only require aqueous cleaning by unloading the relevant baskets on a cover of the bath ( 5 ) and then taking them over from the second transport carriage ( 25 b).

Procedure 2

The parts to be cleaned are fed in the organic pre-cleaning stage A to two standing baths ( 1 ) and ( 2 ) with hot butyl diglycol. After passing through these two baths, they pass through three further baths ( 3-5 ) with warm butyl diglycol, which are piped as a countercurrent cascade. In this case, the ultrasound is used in the first two baths ( 1 ) and ( 2 ).

From the last bath ( 5 ) of the countercurrent cascade, the parts reach the aqueous cleaning stage B and pass through a hot water bath ( 6 ) mixed with the cleaner Extran, a hot rinsing bath ( 7 ), a cleaner bath ( 8 ) mixed with the cleaner ACMH and another hot rinsing bath ( 9 ) with shower attached to it.

Extran consists essentially of non-ionic / ionic Surfactants, polyphosphates, sulfates and complexing agents and ACMH from non-ionic / ionic surfactants, urea, Alcohols.

The parts then get into a water bath ( 10 ), which is kept at room temperature and from there with the third transport device ( 25 c) in a with dewatering fluid, such as. B. White spirit filled with surfactants dewatering bath ( 11 ) immersed. This bath is used to remove any water residues and to increase the service life of the subsequent drying baths ( 12-15 ).

In these drying baths ( 12-15 ) acetone is used at room temperature, the tubs in question being piped together and running as a countercurrent cascade. From the last bath ( 15 ) the basket with the parts to be cleaned is pulled out of the acetone at a defined, slow speed so that the liquid film runs off as completely as possible.

In the exemplary embodiments, butyl diglycol was used as  organic solvent for pre-cleaning and either Called ethanol or acetone for the drying level. To the Instead of the organic solvents mentioned, however a whole range of other substances occur. Usable fabrics for the pre-cleaning with a boiling point above 120 ° C z. B. following chemicals, the flash point of which also consistently 50 ° C is:

n-propyl glycol
(Ethylene glycol mono-n-propyl ether)
n-butyl glycol
(Ethylene glycol mono-n-butyl ether)
Methyl diglycol
(Diethylene glycol monomethyl ether)
Ethyl diglycol
(Diethylene glycol monoethyl ether)
n-butyl diglycol
(Diethylene glycol mono-n-butyl ether)
3-methoxybutanol
(1,3-butylene glycol 3-monomethyl ether)
Tetrahydrofurfuryl alcohol
Diglycol dimethyl ether
(Diethylene glycol dimethyl ether)
Diacetone alcohol
(4-methyl-4-hydroxy-pentanone-2)
Triethylene glycol dimethyl ether
Tetraethylene glycol dimethyl ether
Polyethylene glycol dimethyl ether
Glycol monoacetate
Methyl diglycol acetate
(Diethylene glycol monomethyl ether acetate)
Ethyl diglycol acetate
(Diethylene glycol monoethyl ether acetate)
Butyrolacetone
N-dimethylformamide
N-dimethylacetamide
Metadioxane
(2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane-glycerol dimethyl ketal)
N-methylpyrrolidone

Suitable substances for drying level C are in addition Ethanol and acetone the following solvents with one Evaporation number greater than 2 and a boiling point of 100 ° C or less:

Isopropanol
n-propanol
Tetrahydrofuran
Dimethylacetal
(Acetaldehyde dimethyl acetal)
1.4-dioxane

This list is not exhaustive, so you can further chemicals from those mentioned in claim 1 Find substance classes.

Claims (19)

1. A method for cleaning optical components, which are introduced one after the other into several tanks filled with solvent, wherein

• a) the components are first exposed in a pre-cleaning stage to non-toxic, halogen-free organic solvents that are selected from one or more of the following classes of substances:
• - Aliphatic hydrocarbons,
• cycloaliphatic hydrocarbons,
• - terpenes, terpenoids,
• - aromatic hydrocarbons,
• - alcohols,
• - ketones,
• - esters,
• - ether,
• - glycol ether
• - Ketals
• - acetals
• - nitrogenous hydrocarbon compounds
  or mixtures thereof, the boiling point of the solvents used being above 120 °, the solvent being water-miscible and dissolving polar and non-polar impurities;
• b) the components are then exposed in an aqueous cleaning stage with water mixed with surfactants,
• c) in a subsequent drying stage, the components are exposed to one or more halogen-free, organic, non-toxic solvents, which are selected from the following substance classes:
• - Aliphatic hydrocarbons,
• cycloaliphatic hydrocarbons,
• - alcohols,
• - ketones,
• - esters,
• - ether,
• - acetals
• - Ketals
  or mixtures thereof, where the boiling point of the substances is below 100 ° C and their evaporation number is greater than 2.

2. The method according to claim 1, characterized in that the components from the last bath of the drying stage defined, constant speed will. 3. The method according to claim 1, characterized in that in the pre-cleaning stage, preferably a glycol ether Butyl diglycol is used. 4. The method according to claim 1, characterized in that the pre-cleaning stages contain solubilizing baths. 5. The method according to claim 1, characterized in that in the drying stage ethanol is used. 6. The method according to claim 1, characterized in that in the drying stage acetone is used. 7. The method according to claim 1, characterized in that the substances or solvents in the tubs of the  Drying level warmed to room temperature. 8. The method according to claim 1, characterized in that at least some tubs of the pre-cleaning level or aqueous cleaning stage with ultrasound will. 9. The method according to claim 1, characterized in that the components in the aqueous cleaning stage the cleaning agents are fed to the baths alternately based on surfactants, and rinsing baths with continuous water flow. 10. The method according to claim 1, characterized in that the components with a bath at the beginning of the drying stage Ultrapure water can be supplied. 11. The method according to claim 1, characterized in that the components one or at the beginning of the drying stage several baths with a draining liquid (dewatering fluid). 12. The apparatus for performing the method according to claim 1, characterized in that the troughs ( 3-5 , 1-2 ) at least one of the three successive stages A, B, C are at least partially piped together. 13. The apparatus according to claim 12, characterized in that at least some of the tubs ultrasonic transducers ( 27 a-f) and heating devices are connected. 14. The apparatus according to claim 13, characterized in that each of the three stages AC is provided with its own transport device ( 25 a, b, c) for the tubs. 15. The apparatus according to claim 14, characterized in that the transport device, the ultrasonic transmitter, the heating devices and optionally the gate valves and pumps ( 30 ) are connected to a common control device, so that at least two of the following parameters can be changed under program control: temperature, sound intensity, Sound duration, sequence of the baths, service life of the baths, cycle time of the system. 16. The apparatus according to claim 13, characterized in that the three transport devices an infeed or Ejecting the components between the Pre-cleaning stage and the aqueous cleaning stage and between the aqueous cleaning stage and the Allow drying stage. 17. The apparatus according to claim 12, characterized in that a suction system ( 28 a, b) is guided around the edge of the baths of the cleaning stages or the drying stage. 18. The apparatus according to claim 11, characterized in that the drying stage in a chamber with laminar gas flow (laminar flow box) is installed. 19. The apparatus according to claim 11, characterized in that the electrical installation of the device in explosion-proof construction.