JP7507462B2 - Method for cleaning metal articles - Google Patents

Description

The present invention relates to a method for cleaning metal articles (for example, metal masks used when printing solder paste, etc.).

Solvents are generally used to clean metal articles contaminated with machining oil or the like.
For cleaning metal objects, 1,1,2-trichloro-1,2,2-trifluoroethane (hereinafter referred to as "CFC113") and solvents made of mixtures of CFC113 and alcohol have been used because of its many advantages, such as non-flammability, low toxicity, and excellent solubility. However, CFC113 has been criticized for causing global environmental pollution, such as ozone layer destruction, and alternatives to it are being actively developed.

For example, technologies have been developed that utilize fluoropropenes, which have low ozone depletion potential (ODP) and global warming potential (GWP) due to the presence of double bonds in the molecule and generally have high reactivity with OH radicals in the atmosphere, and which also exhibit cleaning properties due to the inclusion of chlorine atoms. Cis-1-chloro-3,3,3-trifluoropropene (hereinafter also referred to as "HCFO-1233zd(Z)") is known to be useful as a fluoropropene for such cleaning agents, and Patent Documents 1 to 3, for example, disclose cleaning agents that are azeotropic or azeotrope-like compositions that consist of HCFO-1233zd(Z) and other components.

One example of a metal article to be cleaned is a metal mask. In the manufacture of electronic circuits, in order to supply the appropriate amount of solder for joining components to a board, solder paste is sometimes printed through a metal plate with holes in the pattern to be printed, i.e., a metal mask, and this metal mask must be cleaned for storage and reuse after use or to ensure printing accuracy. For example, Patent Document 4 discloses a cleaning agent for metal masks that is an alternative to CFC113, and is mainly made of a glycol ether-based solvent that does not deplete the ozone layer.

JP 2008-133438 A JP 2010-248443 A International Publication No. 2016/052562 Japanese Patent Application Laid-Open No. 9-59688

Cleaning of metal articles is carried out, for example, by immersing the metal articles in a cleaning agent and then removing them from the cleaning agent.
When cleaning metal stencils and other metal objects with a cleaning agent mainly containing glycol ether solvents, the boiling point of the solvent in the cleaning agent is high. As a result, even when the metal object is removed from the cleaning agent, the cleaning agent adhering to the surface of the metal object does not dry and is carried out of the cleaning system, resulting in the problem of using more cleaning agent than necessary and high running costs.

Furthermore, metal masks are usually used and cleaned as a combination plate in which the metal mask is attached to a metal frame via a tensioned gauze. However, when cleaning is done with a cleaning agent mainly containing glycol ether-based solvents, the protective tape or adhesive used in the combination plate deteriorates with repeated cleaning, resulting in high running costs.

Methods for drying metal masks with cleaning agents on them include rinsing with water and drying with hot air, but using these methods not only does not reduce the amount of cleaning agent that needs to be taken out, but also makes the combination plate more susceptible to damage.

On the other hand, even in the conventional technology of cleaning metal articles with cleaning agents mainly containing fluoropropenes, the problem of reducing the amount of cleaning agent taken out is not recognized.
In view of the problems of the conventional technology, the present invention aims to provide a cleaning method capable of cleaning metal articles while suppressing the amount of cleaning agent carried out. Furthermore, in the case where the metal article is a metal mask, in addition to the above-mentioned problems, the present invention aims to provide a cleaning method which is unlikely to deteriorate the adhesive or protective tape used in the combination plate when the combination plate is repeatedly cleaned.

The inventors of the present invention have conducted extensive research to solve the above problems, and have discovered that by immersing a metal object in a cleaning agent containing a fluoropropene compound and then removing the metal object from the cleaning agent at a speed within a specified range, the amount of cleaning agent carried away can be reduced, and when the metal object is a metal mask, deterioration of the adhesive or protective tape used in the combination plate can be suppressed when the metal object is repeatedly cleaned, thereby completing the present invention.

The gist of the present invention is as follows.
[1]
(i) immersing a metal article in a cleaning agent containing a fluoropropene compound (A) represented by the following general formula (1); and (ii) removing the metal article from the cleaning agent at a speed of 0.50 m/sec or less.
1. A method for cleaning a metal article comprising:
_{C3H (6-(a+b)) FaClb} (1 ₎
(In the formula, a is an integer from 1 to 5, b is an integer from 1 to 3, and a+b is an integer from 2 to 6.)

[2]
The cleaning method according to [1] above, wherein the boiling point of the compound (A) is 35° C. or higher and 60° C. or lower.

[3]
The cleaning method according to the above [1] or [2], wherein the cleaning agent contains a fluoropropene compound represented by the following general formula (2) as the compound (A):

(In the formula, R ¹ , R ² and R ³ are each hydrogen, fluorine or chlorine, provided that R ¹ , R ² and R ³ are not all fluorine at the same time, and at least one of R ¹ , R ² and R ³ is chlorine.)

[4]
The cleaning method according to any of the above [1] to [3], wherein the cleaning agent contains, as the compound (A), one or more compounds selected from the group consisting of HCFO-1233zd(Z), HCFO-1233yd(Z), HCFO-1223xd, HCFO-1223za and CFO-1214ya.

[5]
The cleaning method according to [4], wherein the cleaning agent contains HCFO-1233zd(Z) as the compound (A).

[6]
The cleaning method according to any one of the above [1] to [5], wherein the cleaning agent comprises a cleaning composition containing compound (B), which is one or more selected from the group consisting of alcohols, ketones, esters, and hydrocarbons and has a vapor pressure of 1.33 × 10 ³ Pa or more at 20°C, and compound (A).

[7]
The cleaning method according to [6], wherein the alcohol is isopropyl alcohol.
[8]
The cleaning method according to any one of [1] to [7], wherein the metal article is a metal mask.

[9]
The cleaning method according to any one of [1] to [8] above, wherein the temperature of the cleaning agent is 10 to 39° C.

According to the cleaning method of the present invention, it is possible to clean metal objects while suppressing the amount of cleaning agent carried out when removing the metal objects from the cleaning agent. Therefore, it is possible to suppress an increase in the running cost of cleaning due to the carrying out of cleaning agent. Furthermore, when the metal object is a metal mask, it is possible to suppress deterioration of the adhesive or tape used in the combination plate when the metal object is repeatedly cleaned.

FIG. 1 shows an example of a cleaning apparatus that can be used in the cleaning method of the present invention. FIG. 2 shows one embodiment of the orientation of the combination plate when carrying out the cleaning method of the present invention. FIG. 3 shows one embodiment of the orientation of the combination plate when carrying out the cleaning method of the present invention.

The present invention will be described in more detail below. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be modified as appropriate within the scope of its gist.

The method for cleaning metal articles according to the present invention is characterized by comprising the steps of (i) immersing a metal article in a cleaning agent containing a fluoropropene compound (A) and (ii) removing the metal article from the cleaning agent.

(Step (i))
Step (i) is a step of immersing a metal article in a cleaning agent containing a fluoropropene compound (A).

"Washing soap"
The cleaning agent contains the fluoropropene compound (A).

[Component (A)]
The fluoropropene compound (A) (hereinafter also referred to as "component (A)") is a compound having 3 carbon atoms and in which some or all of the hydrogen atoms of a hydrocarbon containing a double bond in the molecule have been substituted with fluorine atoms or chlorine atoms, and is represented by the following general formula (1).

_{C3H (6-(a+b)) FaClb} (1 ₎
(In the formula, a is an integer from 1 to 5, b is an integer from 1 to 3, and a+b is an integer from 2 to 6.)
In order to exhibit an excellent cleaning effect, it is preferable that a is an integer of 2 to 5, b is an integer of 1 or 2, and a+b is an integer of 3 to 6, and it is more preferable that a is an integer of 2 to 5, b is an integer of 1 or 2, and a+b is an integer of 4 to 6.

Specific examples of the fluoropropene compound (A) include chlorofluoropropenes that do not contain hydrogen in the molecule, and hydrochlorofluoropropenes that contain hydrogen in the molecule.

Specific examples of chlorofluoropropene (hereinafter also referred to as "CFO") include:
CFO-1214ya ( _CF3 -CF= _CCl2 ),
E and Z isomers of CFO-1214xb (CF ₃ -CF=CClF),
E and Z isomers of CFO-1215yb (CF ₃ -CCl═CClF),
CFO-1215xc ( _CF3 -CCl= _CF2 ),
etc. can be mentioned.

Specific examples of hydrochlorofluoropropene (hereinafter also referred to as "HCFO") include:
E and Z isomers of HCFO-1223xd (CF ₃ -CCl=CHCl),
E and Z isomers of HCFO-1223zb (CClF ₂ -CH═CClF),
E and Z isomers of HCFO-1223yd (CClF ₂ -CF═CHCl),
HCFO-1223zc ( _CCl2F -CH= _CF2 ),
HCFO-1223za ( _CF3 -CH= _CCl2 ),
HCFO-1232xf ( _CClF2 -CCl= _CH2 ),
HCFO-1232yf ( _CCl2F -CF= _CH2 ),
HCFO-1233xf ( _CF3 -CCl= _CH2 ),
HCFO-1233yd ( _CHF2 -CF=CHCl),
E and Z isomers of HCFO-1233zd (CF ₃ —CH═CHCl);
Examples include the E and Z isomers of HCFO-1241yd (CH ₃ --CF═CHCl).

The cleaning agent may contain one type of fluoropropene compound as component (A), or may contain two or more types of fluoropropene compounds.
As the component (A), in consideration of the balance between drying property and evaporation loss, a fluoropropene compound having a boiling point of 30° C. or higher and 70° C. or lower, preferably 35° C. or higher and 60° C. or lower, is preferred.

Furthermore, among the fluoropropene compounds (A) represented by the general formula (1), the fluoropropene compounds represented by the following general formula (2) are preferred because they have excellent metal stability and excellent cleaning effects.

(In the formula, R ¹ , R ² and R ³ are each hydrogen, fluorine or chlorine, provided that R ¹ , R ² and R ³ are not all fluorine at the same time, and at least one of R ¹ , R ² and R ³ is chlorine.)
Specific examples of CFOs and HCFOs specified by the general formula (2) include HCFO-1233zd(Z), HCFO-1233yd(Z), HCFO-1223xd, HCFO-1223za, and CFO-1214ya. Among these, HCFOs having superior metal stability are preferred, with HCFO-1233zd(Z) being particularly preferred.

[ Cleaning composition]
The cleaning agent may be a composition containing the component (A) and a component other than the component (A).

[Component (B)]
Components contained in the composition other than component (A) include one or more compounds (B) (hereinafter also referred to as "component (B)") selected from the group consisting of alcohols, ketones, esters and hydrocarbons, each of which has a vapor pressure of ^{1.33 x 103} Pa or more at 20°C.

Specific examples of alcohols include methanol, ethanol, n-propanol, and isopropanol (isopropyl alcohol).
The ketones include acetone and methyl ethyl ketone.

Examples of the esters include ethyl formate, propyl formate, isobutyl formate, methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate.
Examples of the hydrocarbons include n-hexane, isohexane, cyclohexane, cyclohexene, 2-methylpentane, 2,3-dimethylbutane, n-heptane, 2-methylhexane, 3-methylhexane, 2,4-dimethylpentane, and isooctane.

When component (B) is used in the present invention, in order to improve the compatibility between component (B) and component (A), the specific gravity of component (B) is preferably within ±0.8 of the specific gravity of component (A) used in combination, and more preferably within ±0.7. In particular, the compatibility of component (A) with other components is highly temperature-dependent, and in order to maintain compatibility at low temperatures, it is important to reduce the difference between the specific gravity of component (A) and the specific gravity of the other components used in combination.

The boiling point of component (B) is preferably within ±40°C of the boiling point of component (A) used in combination, and more preferably within ±30°C, in order to reduce compositional fluctuations during use of the cleaning agent.

The cleaning composition containing the components (A) and (B) is preferably an azeotropic composition or an azeotrope-like composition having a composition close thereto.
Among the components (B), alcohols are particularly preferred. When the dirt adhering to the metal article to be cleaned by the cleaning method of the present invention is solder paste, it is preferable to use alcohols as the component (B).

[Other compounding agents]
If necessary, various auxiliaries such as stabilizers, non-chlorine-based fluorine compounds, ultraviolet absorbers, surfactants, etc. may be added to the composition as long as the effects of the present invention are not impaired.

<Stabilizer>
Examples of the stabilizer include alkenes, nitroalkanes, epoxides, amines, triazoles (excluding benzotriazoles as ultraviolet absorbers described later), water, etc. Furthermore, an antioxidant (a component capable of preventing oxidation of the cleaning agent) may be used as an optional stabilizer.

<Non-chlorine fluorine compounds>
The non-chlorine-based fluorine compound is a fluorine compound in which some of the hydrogen atoms of hydrocarbons or ethers are replaced with only fluorine atoms and does not contain chlorine atoms, and examples thereof include cyclic HFCs, chain HFCs or HFEs that are composed of carbon atoms, hydrogen atoms, oxygen atoms and fluorine atoms and do not contain chlorine atoms, and combinations of two or more compounds selected from these, etc. Specific examples include 4H,5H,5H-perfluorocyclopentane, which is a cyclic HFC, 2H,2H,4H,4H,4H-perfluorobutane and 2H,3H-perfluoropentane, which are chain HFCs, and methyl perfluorobutyl ether and methyl perfluoroisobutyl ether, which are HFEs.

<Ultraviolet absorbing agent>
The ultraviolet absorbing agents include benzophenones, phenyl salicylates, and benzotriazoles.

<Surfactant>
The surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. Examples of the anionic surfactants include fatty acids having 6 to 20 carbon atoms, alkali metals such as dodecylbenzenesulfonic acid, alkanolamines, and amine salts. Examples of the cationic surfactants include quaternary ammonium salts. Examples of the nonionic surfactants include alkylphenols, ethylene oxide adducts of linear or branched aliphatic alcohols having 8 to 18 carbon atoms, and block polymers of polyethylene oxide and polypropylene oxide. Examples of the amphoteric surfactants include betaine-type and amino acid-type amphoteric surfactants.

[Suitable mixing ratio of each component]
The blending ratio of each component is not particularly limited as long as the high detergency, low metal corrosivity, low toxicity, or low flammability of the cleaning agent is not impaired. When the component (B) is blended, its ratio (when multiple types of components (B) are used, the total ratio of the multiple types of components (B)) is preferably 1 to 50 mass%, and more preferably 1 to 30 mass%, relative to 100 mass% of the total of the components (A) and (B).

Metal objects
Examples of materials for the metal article include stainless steel, iron, aluminum, copper, brass and zinc.

Depending on the application, the metal article may be contaminated with contaminants such as cutting oil, press oil, drawing oil, heat treatment oil, rust-preventive oil, lubricating oil, grease, wax, etc.

Examples of the metal articles include metal masks, bearings, automobile parts, precision machine parts such as watches and cameras, electrical equipment parts such as lead frames, and heat treatment parts such as carbide tools.

[Metal mask]
In order to maintain and improve the printing accuracy of printed materials such as solder paste (a paste made by mixing solder powder and flux), and also for the convenience of supplying and installing the printing plate to a screen printer, it is necessary to apply a desired tension to the metal mask on which the printing pattern is formed. For this reason, metal masks are often used as combination plates in which the metal mask is attached to a metal frame via a tensioned gauze. An adhesive is usually used to fix the frame to the gauze and the metal mask to the gauze. This combination plate is manufactured by bonding and fixing the gauze to the frame under a desired tension, then bonding and fixing the metal mask to the center of the gauze at its periphery with an adhesive, and then cutting and removing the gauze inside the periphery. The adhesive part may be covered with a protective tape to prevent contact with a cleaning agent.

The frame is usually made of aluminum.
Examples of the material for the gauze include polyester, nylon, and stainless steel.
Examples of the adhesive include a rubber adhesive, a cyanoacrylate adhesive, an epoxy adhesive, a urethane adhesive, and a UV-curable adhesive.

Examples of the protective tape include aluminum vapor deposition tape, which is made by vapor-depositing aluminum onto the surface of a polyester film base and applying a rubber-based adhesive or acrylic adhesive to the adhesive surface.

When the metal article is a metal mask, the metal mask may be subjected to the cleaning method of the present invention in the form of the combination plate.
After use, the stencil has contaminants such as solder paste (i.e., a paste containing solder powder and flux) adhering to it. In order to store or reuse the stencil after use, or to ensure the printing accuracy of the stencil, the stencil needs to be cleaned after use.

Metal masks have a high level of surface smoothness, and as a result, the cleaning agent is unlikely to remain on the surface when the mask is removed in step (ii), making the mask particularly suitable as a target for cleaning by the cleaning method of the present invention.
Furthermore, according to the cleaning method of the present invention, it is possible to suppress deterioration of the adhesive or tape used in the combination plate when the plate is repeatedly cleaned.

Immerse
In step (i), the metal article, more precisely the metal article having dirt thereon, is immersed in the cleaning agent, whereby the metal article is cleaned (i.e. the dirt is removed).

The cleaning agent is used in liquid form.
The metal article immersed in the cleaning agent may be subjected to physical treatment by a conventionally known method, such as irradiation with ultrasonic waves, shaking the cleaning agent, or submerged jetting of the cleaning agent.

As the cleaning tank for containing the cleaning agent, a cleaning tank provided in a cleaning device described below can be used in addition to a conventionally known cleaning tank.
Furthermore, the cleaning method of this embodiment can be used in combination with a method for suppressing the evaporation loss of the cleaning composition by installing a cooling pipe in the gas phase or by gas recovery, or a recycling method by distillation or filtering.

(Step (ii))
Step (ii) involves removing the metal article from the cleaning material at a speed of 0.50 m/sec or less.

The method for removing the metal articles from the cleaning agent is not particularly limited, and the following method can be used, for example.
First, the metal articles are placed on a metal article transport machine installed in a cleaning tank containing the cleaning agent, and the metal articles are removed from the cleaning agent by moving the metal article transport machine. When using this metal article transport machine, it is usually possible to remove the metal articles from the cleaning agent by moving the metal article transport machine up and down, and to immerse the metal articles in the cleaning agent in the step (i).

As an alternative method, a conveyor having a function of holding the upper end of the metal object and lifting it up (hereinafter referred to as the "lifting function") can be provided outside the cleaning tank, and the metal object can be removed (i.e., lifted up) from the cleaning agent using this conveyor. This conveyor also has a function opposite to the lifting function, specifically, a function of lowering the metal object, and by utilizing this lowering function, the metal object can be immersed in the cleaning agent in step (i).

The metal article transport machine and the transport machine having a lifting function correspond to the transport mechanism (b) in the cleaning device described below.
Furthermore, it goes without saying that the metal articles may be immersed in and removed from the cleaning tank by vertically moving the cleaning tank containing the cleaning agent.

The speed (hereinafter also referred to as "removal speed") is 0.50 m/sec or less, preferably 0.001 to 0.50 m/sec, more preferably 0.005 to 0.25 m/sec, and even more preferably 0.010 to 0.10 m/sec. When the removal speed is equal to or greater than the lower limit, practical work efficiency can be obtained, and when the removal speed is equal to or less than the upper limit, the amount of cleaning agent carried out can be reduced.

If the metal article is a metal mask, it is preferable to orient the thickness direction of the metal mask approximately horizontally when removing it from the cleaning agent. This can further reduce the amount of cleaning agent carried away. In this case, it is even more preferable to tilt the combination plate 11 so that the squeegee surface 12 faces slightly downward from the horizontal direction a when removing the combination plate, as shown in Figure 2. This can prevent cleaning liquid from accumulating on the removed plate frame 13.

Furthermore, when the metal article is a metal mask, as shown in FIG. 3, it is preferable to maintain the metal mask (combination plate) 11 such that its base edge 14 is inclined relative to the horizontal plane 15 when viewed horizontally (this inclination is hereinafter also referred to as the "liquid-draining angle 16"). If the metal mask (combination plate) 11 is removed from the cleaning agent while tilted in this manner, the amount of cleaning agent carried away can be further reduced compared to when it is not tilted. From the viewpoint of not needing to make the cleaning tank excessively large, it is better for this inclination not to be excessively large.

(Cleaning method)
The cleaning method of the present invention includes the above-mentioned step (i) (immersion step) and step (ii) (removal step).

The temperature of the cleaning agent when carrying out the cleaning method of the present invention is preferably 10 to 39°C, more preferably 20 to 39°C, and even more preferably 25 to 35°C. When the temperature is equal to or higher than the lower limit, the amount of cleaning agent taken out when removing the metal article in step (ii) can be reduced. When the temperature is equal to or lower than the upper limit, in the case where the metal article is a metal mask, deterioration of the adhesive and protective tape used in the combination plate when cleaning is repeated can be suppressed.

In the cleaning method of the present invention, by reducing the removal speed and increasing the temperature of the cleaning agent in step (ii), the amount of cleaning agent carried away can be further reduced, and furthermore, the aggregation of moisture in the air on the surface of the metal article, such as a metal mask, that is pulled up and exposed from the cleaning agent can be prevented, thereby suppressing corrosion of the metal article surface.

(Cleaning device)
The cleaning method of the present invention may be carried out using a cleaning apparatus.
The cleaning device may include, as its main structure, a cleaning section (a) in which a cleaning agent is filled and metal articles are cleaned, a transport mechanism (b) for immersing metal articles in the cleaning agent and removing (pulling) them out of the cleaning agent, a cooling mechanism (c) for condensing the vaporized cleaning agent and suppressing its volatilization, a water separation mechanism (d) for separating the condensed cleaning agent from the water adhering to the cooling pipe, and a dirt separation mechanism (e) for separating dirt components carried into the cleaning agent. An example of the cleaning device is shown in Figure 1.

In the cleaning apparatus shown in FIG. 1, the cleaning section (a) includes a cleaning tank 1, a mechanism for heating a cleaning agent such as a heater 2, and an ultrasonic vibrator 5.
The transport mechanism (b) may be a metal article transport machine such as a metal mask transport machine, or a transport machine having a lifting function (not shown).

The cooling mechanism (c) includes a cooling pipe 6 for cooling and condensing the vaporized cleaning agent.
The water separation mechanism (d) includes, for example, a water separation tank 7, a pipe 8 for condensate before water separation, and a pipe 9 for condensate after water separation.

The dirt separating mechanism (e) includes a cleaning agent circulating pump 3, a dirt separating filter 4 and a cleaning agent pipe 10.
When using this cleaning device to clean metal articles, the metal articles are immersed in the cleaning agent contained in the cleaning tank 1 using a metal article transport machine and cleaned, and after cleaning, the articles are removed (pulled up) at a constant speed using the transport mechanism (b).

In the cleaning section (a), the cleaning agent filled in the cleaning tank 1 is heated by the heater 2, and ultrasonic waves are irradiated onto the metal objects by the ultrasonic transducer 5 while controlling the temperature of the cleaning agent at a constant temperature, thereby further enhancing the cleaning effect.

By removing (pulling up) the metal articles after immersion at a predetermined speed using the conveying mechanism (b), it is possible to reduce the amount of cleaning agent adhering to the surface of the metal articles and being carried out of the cleaning device to almost zero, making it possible to reduce running costs due to the removal of cleaning agent. If a conveying machine with a lifting function is installed in a location that does not come into contact with the cleaning agent instead of the metal article conveying machine, the amount of cleaning agent carried out can be further reduced.

Furthermore, the cleaning tank 1, which can be moved up and down, may be used as a device equipped with a mechanism for removing the metal articles from the cleaning agent.
The transport mechanism (b) may be an actuator using air or oil, inverter control, or the like.

In the water separation tank 7, the condensate collected in the cooling pipe 6 is left to stand and separated from the water adhering to the cooling pipe, preventing water from entering the cleaning tank 1, which can cause poor cleaning, and suppressing evaporation loss due to the volatilization of the cleaning agent.

In the dirt separation mechanism (e), dirt and other contaminants removed from metal objects and contained in the cleaning agent in the cleaning tank 1 are continuously removed using a cleaning agent circulation pump 3 and a dirt separation filter 4, preventing the metal objects from becoming recontaminated, maintaining excellent cleaning performance, and achieving high drying properties.

By using this cleaning device to control the lifting speed within a specified range when lifting metal objects from the cleaning agent, it is possible to reduce the amount of highly volatile cleaning agent (amount of cleaning agent carried out) that adheres to the surface of the pulled metal objects and is carried out of the system after cleaning.

The separation filter may be provided with a reinforcing material such as wire mesh, plastic, or a fiber structure for the purpose of reinforcement. It is also possible to place a prefilter, such as a membrane-like or cotton-like dust-collecting material, to collect dust and the like before passing the return liquid through the separation filter.

The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited in any way to the following examples.

(Metal mask (combination version))
Details of the metal mask (combination type, manufactured by Sonocom Co., Ltd.) used in the examples are as follows.

Frame: Aluminum 450mm x 450mm x 25mm
Metal mask: SUS 300mm x 300mm x 0.12mm
Gauze: Polyester mesh (#225)
Adhesive used to bond the metal mask and gauze: Urethane adhesive Protective tape: Protective tape made of polyester film with aluminum vapor deposition and acrylic adhesive

[Examples 1 to 15, Comparative Examples 1 to 13]
(Washing soap)
In each example, detergents 1 to 5 were prepared by mixing the components in the proportions shown in Table 1 or by using component (A) as is. The meanings of the abbreviations in Table 1 are as follows:

Component (A)
1233zd; cis-1-chloro-3,3,3-trifluoropropene 1223xd; 1,2-dichloro-3,3,3-trifluoropropene 1233yd; cis-1-chloro-2,3,3-trifluoropropene Component (B)
IPA: Isopropyl alcohol Other compounding agents (stabilizers)
MB: 2-methyl-2-butene PO: Propylene oxide In Comparative Example 1, a glycol ether-based cleaning agent (product name: EBA CLEAN EE3700, manufactured by Rasa Koei Co., Ltd.) was used as cleaning agent C1. In Comparative Example 2, SOLKANE (registered trademark) 365 manufactured by Nippon Solvay Co., Ltd., which is a commercially available hydrofluorocarbon (HFC-365mfc), was used as cleaning agent C2.

The compositions of cleaning agents 1 to 5, C1, and C2 are shown in Table 1.

(Metal articles)
The metal article to be cleaned was the above-mentioned combination metal mask with 5 g of solder paste (product name: SJM-10W GT, manufactured by Nippon Almit Co., Ltd.) evenly applied thereto.

(Washing process)
In a room adjusted to 21-25°C and humidity 66-82%, each of the cleaning agents listed in Table 2 was placed in a metal mask cleaning machine UC400 (manufactured by Sharp Manufacturing Systems Co., Ltd.), the combination plate was immersed in the cleaning agent, and ultrasonic waves (35 kHz, 600 W) were applied to the combination plate for 1 minute. During the immersion, the temperature of the cleaning agent was kept at 30-35°C. The combination plate was then removed (pulled up) at a speed of 0.015 m/sec. When removing (pulling up), the combination plate was maintained so that the squeegee surface of the metal mask was facing slightly downward from the horizontal direction, and the base side of the combination plate was tilted upward by about 10° with respect to the horizontal plane when viewed from the thickness direction of the metal mask, as shown in Figures 2 and 3.

Cleaning properties
The removed metal mask was visually observed to evaluate the cleaning property. The evaluation results are shown in Table 2. The symbols in the table have the following meanings.

◯: No solder paste remaining X: Solder paste remaining When solder paste remaining was found, the following evaluation of the amount of solder carried out and the surface temperature was not carried out.

<Liquid output>
The weight _W0 (g) of the combination plate before the solder paste was applied and before it was immersed in the cleaning agent, and the weight _W1 (g) of the combination plate immediately after it was pulled up and completely exposed from the cleaning agent (including the weight of the cleaning agent if any) were measured using an electronic balance (electronic balance (EB4000H, manufactured by Shimadzu Corporation, read limit: 10 mg)), and the amount of liquid carried over was calculated using the following formula.

Amount of liquid carried (g) = W ₁ - W ₀
The evaluation results are shown in Table 2. The symbols in the table have the following meanings.
A: Less than 1g of liquid carried over B: 1g or more and less than 5g of liquid carried over C: 5g or more and less than 10g of liquid carried over D: 10g or more of liquid carried over

<Surface temperature of metal mask>
The surface temperature of the center of the combination metal mask immediately after it was pulled up and completely exposed from the cleaning agent was measured with a surface thermometer (TX1001, manufactured by Yokogawa Measurement Co., Ltd.). The measurement results are shown in Table 2. The symbols in the table have the following meanings:

a: Surface temperature is 25°C or higher b: Surface temperature is 20°C or higher and lower than 25°C c: Surface temperature is 15°C or higher and lower than 20°C d: Surface temperature is lower than 15°C

[Examples 16 to 20, Comparative Examples 14 and 15]
In Example 16, the cleaning process of Example 1 was repeated 20 times. Specifically, after carrying out the cleaning process of Example 1, 5 g of solder paste was uniformly applied again to the metal mask of the combination plate that had been pulled up, the combination plate was immersed in the cleaning agent, and ultrasonic waves were irradiated for 1 minute, after which the combination plate was removed (pulled up) at a speed of 0.015 m/sec. This operation was repeated 19 times.

The condition of the adhesive and protective tape used on the combination plate was then evaluated.
In Examples 17 to 20 and Comparative Examples 14 and 15, the same procedures and evaluations as in Example 16 were performed, except that the cleaning agents were changed to those shown in Table 3. In Comparative Example 15, the solder paste remained on the metal mask after it was removed from the cleaning agent, so the solder paste was not applied repeatedly.

The evaluation results are shown in Table 3. The symbols in Table 3 have the following meanings.
<Adhesive>
○: No change ×: Peeling or loosening of the gauze occurred <Protective tape>
○: No change ×: Peeling or fine bubbles appearing on the adhesive surface

1 Cleaning tank 2 Heater 3 Cleaning agent circulation pump 4 Dirt separation filter 5 Ultrasonic vibrator 6 Cooling pipe 7 Water separation tank 8 Pipe for condensate before water separation 9 Pipe for condensate after water separation 10 Cleaning agent pipe 11 Combination plate (metal mask)
12 Squeegee surface 13 Frame a Horizontal direction 14 Bottom edge 15 Horizontal surface 16 Draining angle

Claims (8)

(i) immersing a metal article in a cleaning agent containing a fluoropropene compound (A) represented by the following general formula (1); and (ii) removing the metal article from the cleaning agent at a speed of 0.50 m/sec or less.
Including,
The metal article is a metal mask used as a combination plate .
A method for cleaning metal articles.
C ₃ H _(6-(a+b)) F _a Cl _b (1)
(In the formula, a is an integer of 1 to 5, b is an integer of 1 to 3, and a+b is an integer of 2 to 6.) The cleaning method according to claim 1, wherein the boiling point of the compound (A) is 35°C or higher and 60°C or lower. 3. The cleaning method according to claim 1, wherein the cleaning agent contains a fluoropropene compound represented by the following general formula (2) as the compound (A):

(In the formula, R ¹ , R ² and R ³ are each hydrogen, fluorine or chlorine, provided that R ¹ , R ² and R ³ are not all fluorine at the same time, and at least one of R ¹ , R ² and R ³ is chlorine.) The cleaning method according to any one of claims 1 to 3, wherein the cleaning agent contains, as compound (A), one or more compounds selected from the group consisting of HCFO-1233zd(Z), HCFO-1233yd(Z), HCFO-1223xd, HCFO-1223za, and CFO-1214ya. The cleaning method according to claim 4, wherein the cleaning agent contains HCFO-1233zd(Z) as the compound (A). The cleaning method according to any one of claims 1 to 5, wherein the cleaning agent comprises a cleaning composition containing compound (B), which is at least one selected from the group consisting of alcohols, ketones, esters, and hydrocarbons and has a vapor pressure of 1.33 x 10 ³ Pa or more at 20°C, and compound (A). The cleaning method according to claim 6, wherein the alcohol contains isopropyl alcohol. The cleaning method according to any one of claims 1 to 7, wherein the temperature of the cleaning agent is 10 to 39°C.

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