JPH06312102A - Finish drying - Google Patents

Abstract

PURPOSE:To perform finish drying which leaves almost no stain and residues and is almost free from inflammability without using FUC gas. CONSTITUTION:Finish drying is performed using octamethyltrisiloxane or octamethylcyclotetrusiloxane which contains less than 0.01wt.% of dodecamethylpentasiloxane and does not contain a chemical compound with inferior volatility to dodecamethylpentasiloxane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention eliminates the need for using CFCs and is performed in the final step of the cleaning process for optical parts such as glass lenses and plastic parts, mold parts, metal parts, ceramic parts and electronic parts. The present invention relates to a finish drying method, in particular, a finish drying method which is free from stains, residues, etc. and does not cause any trouble in the surface treatment such as a vacuum deposition film performed after cleaning.

[0002]

2. Description of the Related Art As a finishing drying method,
Vapor finish drying of 1,2-trichloro-1,2,2-trifluoroethane (CFC 113) has been used. This is because CFC 113 is non-flammable; it has low toxicity to living organisms; it does not erode polymeric materials such as plastics and rubber, but it has selective solubility of dissolving oils and fats; excellent drying speed, etc. This is because it has features.

However, in recent years, there has been a regulation to reduce the amount of CFC 113 used due to protection of the ozone layer, and therefore various mixtures and azeotropic compositions have been developed for the purpose of CFC substitution. For example, Japanese Patent Application Laid-Open No. 1-318094 discloses a mixture of Freon 113 with isopropyl alcohol and methyl ethyl ketone, and Japanese Patent Application Laid-Open No. 2-289693 describes dichlorotetrafluoropropane (CFC 234) and an aliphatic lower alcohol such as ethanol. Azeotropic compositions are disclosed. In addition, isopropyl alcohol (I
Vapor finish drying using PA) is also performed.

[0004]

By the way, Freon 11
Since perhaloethanes such as 3 are chemically stable, they have a long life in the troposphere, diffuse and reach the stratosphere, where the chlorine radicals decomposed by solar rays cause a chain reaction with ozone to generate ozone. There is a need to reduce their use because they destroy the layers. Therefore, as a method for reducing the usage amount, an azeotropic composition of CFC 113 and an organic solvent other than perhaloethane has been studied as described above. However, since CFC 113 is essential, the usage amount is reduced to some extent or more. It is not possible. Also, Freon 2
34 is relatively less destructive to the ozone layer than Freon 113, but cannot completely eliminate the destruction of the ozone layer. On the other hand, the finish drying using IPA vapor has the influence of water and the like, and also has an inflammability, and the risk of ignition due to the use of this flammable substance in a vapor state.
There is a problem such as deterioration of plastic etc. and it is not practical.

Therefore, the present invention has been made in view of these problems, and it is used in a liquid state that is not easily affected by water and has a low risk of ignition, without using CFCs that destroy the ozone layer. It is an object of the present invention to provide a finish drying method that does not immerse plastics and the like and that has no stains or residues after drying.

[0006]

Means and Actions for Solving the Problems In the finish drying method of the present invention, a compound having a content of dodecamethylpentasiloxane of less than 0.01% by weight and being less volatile than dodecamethylpentasiloxane is substantially used. The low-molecular-weight siloxane removed in step 1 is used as a finishing drying liquid. The reason for using the low-molecular-weight siloxane is that it has excellent properties such as high safety to human body, low attack to plastic, low surface tension and good permeability. Here, the state of being substantially removed means a level that is not detected even by using a general separation analysis such as GC (gas chromatography) and LC (liquid chromatography). Further, the vapor pressure is used as a standard for grasping the degree of volatility, and in addition, it is grasped in consideration of the latent heat of vaporization and the like.

The low-molecular-weight siloxane used in the present invention may be either a linear siloxane or a cyclic siloxane, and these siloxanes may be used alone or as a mixture. Considering volatility and risk of ignition, octamethyltrisiloxane or octamethylcyclotetrasiloxane is desirable and practical. It is also possible to use a mixed system of these low molecular weight siloxanes.

In the finish drying step, the above-mentioned finish drying liquid of the washing step or the water replacement step is dipped and pulled up, and then left to stand at room temperature, dried by blowing air or reduced pressure to finish drying. These drying methods can be used alone or in combination.

In the present invention, it is possible to add a stabilizer and the like, but it is necessary that the stabilizer has a large effect of stabilizing the composition used in the present invention.
More preferably, those that are co-distilled by the distillation operation or those that form an azeotropic distillation are desirable.

The low-molecular-weight siloxane used in the finish drying method of the present invention is obtained by removing dodecamethylpentasiloxane by distillation / rectification or / and adsorption of activated carbon. Since this composition contains less than 0.01% by weight of dodecamethylpentasiloxane and is less volatile than dodecamethylpentasiloxane, it removes stains after drying by blowing air or drying under reduced pressure.
No residue is generated.

In the present invention, it is possible to confirm the influence of a trace amount of a component having poor volatility on the finishing state by the following experiment. Purity 99.99 in gas chromatography obtained using a distillation apparatus with a theoretical plate number of 30 or more
Dodecamethylpentasiloxane was added to each of 9% or more of octamethyltrisiloxane and octamethylcyclotetrasiloxane in an amount of 0.001% by weight, and a clean slide glass was dipped in each liquid and pulled up to perform air drying.
After that, an exhalation test is performed to judge the condition of stains and residues from the binocular stereomicroscope and the cloudy condition when exhaled.

Similarly, tetradecamethylhexasiloxane is added in an amount of 0.001% by weight, and the same experiment is conducted.
In this evaluation, “O” indicates that no stain or residue was observed in either the binocular stereoscopic microscope observation or the breath test, and “X” indicates that stain or residue was observed in either observation. The results are shown in Table 1. However, Table 1 is an excerpt from the above-mentioned experiment. As can be understood from these results, dodecamethylpentasiloxane is 0.0
If it is contained in an amount of more than 1% by weight, or even a small amount of tetradecamethylhexasiloxane having a lower volatility than dodecamethylpentasiloxane is contained, stains and residues are generated.

[0013]

[Table 1]

From the above, the finish-drying liquid used in the finish-drying method of the present invention contains less than 0.01% by weight of dodecamethylpentasiloxane, and is a low-volatility compound obtained by removing a compound less volatile than dodecamethylpentasiloxane. It uses a molecular siloxane.

The low-molecular-weight siloxane used in the present invention has little toxicity to living bodies, is chemically stable, and has almost no effect on plastics, rubbers, metals, glasses and the like. Moreover, since it does not contain halogen such as chlorine, it does not affect the ozone layer and is highly safe.

[0016]

Example 1 A glass lens, a plastic made of polymethylmethacrylate (PMMA) and polycarbonate (PC), and a metal part made of aluminum were washed by the following procedure. First, the cleaning product was degreased while applying ultrasonic waves in an alkali saponifying agent, and then degreased again while applying ultrasonic waves in a surfactant. After that, water washing was performed while applying ultrasonic waves to clean water to remove the surfactant, and further washing was performed while applying ultrasonic waves to pure water to remove ions and stains of the clean water to enhance the cleaning degree. Then, it was washed with IPA as a drainer of pure water. Finally, a distillate obtained by using octamethyltrisiloxane in a distiller having a theoretical plate number of 30 or more was used as a finishing drying liquid, and the washed product was immersed in this drying liquid, pulled up, and then dried by blowing air.

Gas chromatographic analysis of the above-described finishing dry liquid used in this Example showed that the content of dodecamethylpentasiloxane was 0.009%, and that the compound having a lower volatility than dodecamethylpentasiloxane was found. I couldn't do it. The analysis conditions of gas chromatography are
Using a gas chromatography under the product name GC14A (manufactured by Shimadzu Corporation), the injection temperature is 260 ° C, the detection temperature is 280 ° C, and 10 ° C from 50 ° C to 250 ° C.
The temperature was raised at / min and the measurement was performed using an FID detector and OV-1 capillary column. A binocular stereomicroscope and an exhalation test were performed as an evaluation of the finish dry state. As a result, no stain or residue was observed, and good finish drying could be performed.

[0018]

Example 2 A glass lens, a plastic lens made of PMMC and PC, and an aluminum metal part were washed by the following procedure. First, the cleaning product was degreased while applying ultrasonic waves in an alkali saponifying agent, and then degreased again while applying ultrasonic waves in a surfactant. After that, water washing was performed while applying ultrasonic waves to clean water to remove the surfactant, and further washing was performed while applying ultrasonic waves to pure water to remove ions and stains of the clean water to enhance the cleaning degree. Then, as a drainer of pure water, IP
Washed with A. Finally, a distillate obtained by using octamethylcyclotetrasiloxane in a distiller having a theoretical plate number of 30 or more is used as a finishing dry liquid, and the washed product is immersed in the dry liquid and pulled up, and then dried by blowing air. . When the finishing dried liquid used in this example was analyzed by gas chromatography, it was found that the amount of dodecamethylpentasiloxane was 0.0
It was 09%, and no compound having inferior volatility to dodecamethylpentasiloxane was observed.

Also in this example, the evaluation of the finish dry state was carried out by a binocular stereoscopic microscope and an exhalation test as in Example 1. As a result, no stain or residue was observed, and good finish drying could be performed.

[0020]

Example 3 The composition to be used in the present invention was tested for the attack property on the article to be cleaned. Test pieces (5 × 50 ×) made of acrylic resin (PMMA), polycarbonate with glass filler (PC), polypropylene resin (PP), and acrylonitrile-butadiene-styrene (ABS)
(2 mm) was placed in a glass bottle and filled with 100 g of octamethyltrisiloxane and octamethylcyclotetrasiloxane used as the finishing drying liquid of Examples 1 and 2, left standing at room temperature and normal humidity for 48 hours, taken out, and then changed in weight. And the appearance change was examined. The results are shown in Table 2.

[0021]

[Table 2]

[0022]

EFFECTS OF THE INVENTION The finish drying method of the present invention can be used in a liquid state that does not destroy the ozone layer, is not easily affected by water, and is less likely to catch fire, and does not soak plastics or the like. , Stains, residues, etc. are gone.

Claims (3)

[Claims] 1. A finishing dry liquid in which the content of dodecamethylpentasiloxane contained in the low-molecular-weight siloxane is less than 0.01% by weight, and substantially no compound having a lower volatility than dodecamethylpentasiloxane is contained. A method of finish drying, which comprises using 2. An octamethyltrisiloxane having a dodecamethylpentasiloxane content of less than 0.01% by weight and containing substantially no compound less volatile than dodecamethylpentasiloxane. The finish drying method according to claim 1. 3. Use of octamethylcyclotetrasiloxane having a dodecamethylpentasiloxane content of less than 0.01% by weight and substantially not containing a compound having a lower volatility than dodecamethylpentasiloxane. The finishing drying method according to claim 1.