JP2015213849A - Cleaning medium and dry cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning medium hard to damage the base material of a cleaning object to be capable of selectively removing rigid membranous dirt firmly sticking to a surface layer.SOLUTION: In a cleaning medium used by being pressed repeatedly on a cleaning object while flying with swirl streams, as shown in Fig.4, the physical property of the cleaning medium is limited to a range of fracture toughness at 1-10[MPa m] and Vickers hardness at 100Hv[kgf/mm] or above. When the fracture toughness exceeds 10, the cleaning medium stretches by an increase in ductility, so that corner (edge) rounds to decrease cleaning power. When the fracture toughness is smaller than 1, the cleaning medium easily cracks to make a difficulty in holding a long-period cleaning power. When the Vickers hardness is less than 100, even moderate cracks of the cleaning medium with generation of edges cannot cope with a rigid cleaning object, so that cleaning power extremely drops.

Description

  The present invention relates to a cleaning medium that is used so as to be repeatedly applied to an object to be cleaned while flying with a swirling airflow, and a dry cleaning apparatus using the cleaning medium.

In recent years, from the viewpoint of reducing the environmental load, a dry cleaning apparatus has been proposed that removes dirt adhered to an object to be cleaned using a solid cleaning medium without using water or a solvent.
Patent Document 1 discloses a handy-type dry cleaning device that can arbitrarily change a cleaning position for an object to be cleaned.
This cleaning device has an intake means for sucking air and a cleaning casing connected to the intake means by a flexible hose.
The cleaning housing has an internal space for circulating and flying the cleaning medium, and an opening for causing the cleaning medium flying in the internal space to collide with the object to be cleaned.
Furthermore, it has an air passage that allows air from the outside to pass through the internal space, an air inlet connected to the air intake means, and a porous means such as punching metal that allows the removed object removed from the object to be cleaned to pass through the air intake side. doing.

The cleaning position can be easily changed by holding and moving the cleaning housing by hand.
When the intake means is operated, a large amount of external air flows into the internal space mainly from the opening, and the internal space is in a negative pressure state.
When a predetermined amount of the cleaning medium is sucked from the opening in the negative pressure state, the cleaning medium sticks to the porous means and is held inside the cleaning casing.
In this state, when the opening is covered with the part to be cleaned of the object to be cleaned, external air flows at a high speed from the air passage having a smaller cross-sectional area than the opening, and a swirling airflow is generated in the internal space, which is stretched on the porous means. The attached cleaning medium flies.
The cleaning medium that continues to circulate in the interior space rides on the airflow flowing at high speed from the ventilation path and flies linearly toward the opening at high speed, and collides with the object to be cleaned exposed at the opening to remove dirt. To do. Washing proceeds by repeating this collision operation.

As the cleaning medium, as described in Patent Document 1, resins such as polycarbonate, polyethylene terephthalate, acrylic, and cellulose, minerals such as paper, cloth, and mica, ceramics, glass, and metals can be used. There are a wide variety of things.
The material of the cleaning medium is appropriately selected according to the type and degree of dirt on the object to be cleaned.
Although a flaky plastic (resin film) is mentioned as a very general-purpose cleaning medium, if the fixed contamination of the object to be cleaned exceeds a certain level of hardness, teeth will not stand and it will be difficult to remove the contamination.
When removing strongly adhered film-like dirt, it is generally easy to remove dirt by using a hard cleaning medium, but on the other hand, the base material of the object to be cleaned is damaged, and a high-quality cleaning surface is obtained. It's hard to be done.

For this reason, there is an increasing need for a cleaning medium that does not damage or hardly damage the base material and can selectively remove even dirt that adheres firmly to the surface layer.
However, there are a wide variety of cleaning media that can be used, and it is not easy to select an optimal one among them.
As a characteristic of the cleaning medium in this type of dry cleaning, it is known that it is necessary to maintain a certain cleaning ability (cleaning performance) that a new edge is generated by appropriate cracking in several collisions. ing.
That is, when the function of removing dirt by cutting into the dirt layer at the edge is reduced, the cleaning ability is recovered by cracking and generating a new edge, thereby maintaining a constant washing ability. be able to.

Patent Document 1 proposes that it is effective to use two physical property values of “pencil hardness” and “folding resistance” as a criterion for selecting a cleaning medium.
"Pencil hardness" is the hardest pencil core number measured by a method in accordance with JIS K-5600-5-4, with no scratches or dents on the evaluated flaky cleaning medium. To do.
“Folding resistance” is measured in accordance with JIS P8115, and means the number of reciprocations until a flaky cleaning medium is bent to 135 degrees at R = 0.38 mm until it is damaged. .

However, the hardness of the flakes that can be evaluated by folding resistance is 2H or less in terms of pencil hardness, and can only be applied to stains having a hardness of 2H or less.
The hardness of a general coating film is about 4H to 9H in pencil hardness, and a hardness of 9H or more is required for the cleaning medium.
On the other hand, even if it has a hardness of 9H or more, there is a problem that if it is hard only, it is fragile at the time of collision, and the cleaning medium is shattered before the above-described dirt removal function by the edge is not fully expressed.

  The present invention has been made in view of such a current situation, and is a cleaning medium that is hard to damage the base material of the object to be cleaned and can selectively remove hard film-like dirt firmly adhered to the surface layer. Is the main purpose.

Through experiments, the present inventors have found that in a cleaning medium having a pencil hardness of 4H or more, the physical property value of fracture toughness has an effect on how the cleaning medium is cracked, and the hardness that causes edge generation cracks without being shattered. Found it to exist.
Based on this finding, the present invention provides a fracture toughness of 1 to 10 [MPa · m ^1/2 ] and a Vickers hardness of a cleaning medium that is used to repeatedly apply to a cleaning object while flying with a swirling airflow. It was defined as 100 Hv [kgf / mm ² ] or more.
Fracture toughness is a value indicating resistance to crack growth, as shown in Non-Patent Document 1, for example.
The test is standardized by ASTM D5045 (Plane strain fracture toughness and energy release rate of plastic materials (≈ ISO 13586)). ASTM is an abbreviation for American Materials and Testing Association.

  According to the present invention, it is difficult to damage the base material of the object to be cleaned, and it is possible to selectively remove hard film-like dirt firmly adhered to the surface layer.

It is a schematic sectional drawing which shows the structure which becomes the basis of the dry cleaning apparatus of this invention. It is a figure which shows the washing | cleaning operation | movement of the dry cleaning apparatus. It is a perspective view which shows the use condition of the dry cleaning apparatus. It is a figure which shows the characteristic about the fracture toughness and Vickers hardness of various washing | cleaning media. It is a figure which shows the characteristic about the Vickers hardness of various washing | cleaning media. It is an image figure which shows the thin piece of silicon nitride as a washing | cleaning medium. 4 is a graph showing experimental results of Example 1. It is an enlarged image figure of the thin piece of silicon nitride before washing. It is an enlarged image figure of the thin piece of silicon nitride after washing. 6 is a graph showing experimental results of Example 2. 10 is a graph showing experimental results of Example 3. 10 is a graph showing experimental results of Example 4. 10 is a graph showing experimental results of Example 5. It is a figure which shows the characteristic of the cleaning capability of cast iron. 10 is a graph showing experimental results of Example 6.

Embodiments of the present invention will be described below with reference to the drawings.
First, the dry cleaning apparatus according to this embodiment will be described with reference to FIGS. 1 to 3.
An outline of the configuration of the handy type dry cleaning device 2 will be described with reference to FIG. FIG. 1A is a transverse sectional view taken along line AA, and FIG. 1B is a longitudinal sectional view taken along line BB.
The dry cleaning device 2 includes a dry cleaning casing (hereinafter also simply referred to as “casing”) 4 having a flying space (internal space) for the cleaning medium 5 therein, and an intake means 6 for reducing the pressure inside the casing 4. And.

The casing 4 is configured integrally with a cylindrical upper casing 4A as a casing main body and an inverted conical lower casing 4B. Here, the upper part and the lower part are convenient names on the drawing, and are not necessarily related to the upper and lower sides on the actual machine.
The lower housing 4B is integrally provided with an intake port 8 at the top of the conical shape, and functions as a suction duct.
The suction means 6 has a flexible suction hose 10 connected at one end to the suction port 8 and a suction device 12 connected to the other end of the suction hose 10.
As the suction device 12, a household vacuum cleaner, a vacuum motor, a vacuum pump, or a device that indirectly generates a low pressure or a negative pressure by pumping fluid can be used as appropriate.
Note that the positional relationship between the upper and lower surfaces of the member is merely a reference on the drawing.

The bottom surface of the upper housing 4A is a fitting recess 4A-1 that joins the upper end of the lower housing 4B, and the upper housing 4A and the lower housing 4B are separable. The upper surface 4A-2 of the upper housing 4A is sealed.
A porous separation plate 14 is provided as a porous means at the boundary between the bottom surface of the upper housing 4A and the lower housing 4B.
The separation plate 14 is a plate-like member having holes such as punching metal.
The separation plate 14 prevents the cleaning medium 5 from moving to the lower housing 4B side (intake port side) when sucked.

In FIG. 1A, a part of the display of the separation plate 14 is omitted. The size of the cleaning medium 5 is exaggerated for easy understanding.
The porous means may be a porous shape having many pores having a size that allows air and dust (removed material removed from the object to be cleaned) to pass through without passing through the cleaning medium 5.
That is, as the porous means, a slit plate, a net, or the like may be used, and a resin, metal, or the like may be freely selected as long as the material has a smooth surface.
The porous means is arranged as a plane orthogonal to the swirling axis of the swirling airflow. Thereby, there exists an effect which prevents retention of the washing | cleaning medium 5 by an airflow flowing in the direction along a porous means.
In order to suppress the attenuation of the swirling airflow, it is desirable that the inner surface of the housing is smooth without steps and irregularities.

The porous means is arranged on the surface along the swirling airflow, so that the cleaning medium adsorbed on the surface can be re-flighted.
The material of the housing 4 is not particularly limited, but is preferably made of metal such as aluminum or stainless steel in order to prevent wear due to adhesion of foreign matter or friction with the cleaning medium, but a resinous material may be used. it can.
A cylindrical channel restricting member 16 is provided as a part of the casing at the center of the upper casing 4A so that the cylindrical axis of the upper casing 4A is a common axis. The lower end is fixed to the separation plate 14.
The channel restricting member 16 is provided for the purpose of improving the flow velocity by reducing the channel cross-sectional area of the swirling airflow.
A ring-shaped swirling airflow moving space (internal space as a flying space for the cleaning medium) having a smooth wall surface is formed in the upper housing 4A by the flow path restriction member 16.

Depending on the shape of the upper casing 4A, the central axis of the flow path restricting member 16 and the central axis of the upper casing 4A do not necessarily have to be common, and may be eccentric if a ring-shaped space can be secured. good.
An opening 18 is formed in a part of the side surface of the upper housing 4A to allow the cleaning medium 5 flying with a swirling airflow to contact or collide with an object to be cleaned.
The upper housing 4A has a cylindrical shape whose height is extremely small with respect to the diameter, and an opening 18 is provided in a part of a side surface forming the height.
As shown in FIG. 1B, the entire casing 4 has a layout in which the outer peripheral portion other than the opening 18 largely escapes (leaves) from the object 20 to be cleaned, that is, local contact with the object 20 to be cleaned, in other words, This increases the degree of freedom of pinpoint cleaning.

The opening 18 has a shape obtained by cutting the side surface of the upper housing 4A by a flat cross section parallel to the cylindrical axis, and has a rectangular shape when viewed from a direction orthogonal to the cylindrical axis.
An air inlet 22 is formed on a side surface of the upper housing 4A, and an inlet 24 as a ventilation path is connected to the air inlet 22 from the outside of the upper housing 4A so as to be integrated with the upper housing 4A. It is fixed.
The inlet 24 is set substantially parallel to the separation plate 14, and the ventilation direction thereof is inclined with respect to the radial direction of the upper housing 4 </ b> A, and the extension line at the center of the ventilation path is positioned so as to reach the opening 18. Yes.
The inlet 24 has a width extending in the height direction of the upper housing 4A.
One inlet 24 having a diameter or width smaller than the height of the upper housing 4A may be arranged, or a plurality of single inlets may be arranged in the height direction.

  All of the air inlet 8, the opening 18, and the inlet 24 communicate with the internal space 26. The inner peripheral side of the internal space 26 is defined by the flow path restriction member 16.

As shown in FIG. 1, when the opening 18 is in contact with the surface to be cleaned of the object 20 to be closed, the inside of the housing 4 becomes a closed space and is introduced into the internal space 26 via the inlet 24. Air is sucked into the intake port 8 side.
For this reason, outside air flows from the inlet 24 at a high speed, and this high-speed air flow accelerates the cleaning medium 5 toward the opening 18 and generates a swirling air flow 30. The annular inner space 26 is also a swirl flow path.
The swirling airflow generated when the closed space is formed has the effect of blowing away the cleaning medium adsorbed and held on the separation plate 14 by the negative pressure due to the intake air and re-flying it.
The opening 18 has an area large enough to bring the internal pressure at the air inlet 22 to atmospheric pressure or in the vicinity thereof when the opening 18 is separated from the cleaning target 20 and opened.
Further, the air inlet 22 is also arranged at a position where the atmospheric pressure or the vicinity thereof tends to be reached when the opening 18 is opened.

By providing such a configuration, while the dry cleaning device 2 is not applied to the object to be cleaned, the air inlet 22 approaches the atmospheric pressure, so that the differential pressure with the outside decreases, and the airflow that flows in as a result. Is dramatically reduced.
On the other hand, since the airflow flowing in from the opening 18 increases, the cleaning medium 5 can be prevented from leaking out of the housing 4.
In addition, when the opening 18 is opened, the total amount of airflow flowing in is 2 to 3 times as compared with when the opening 18 is closed, so that the lamellar cleaning medium is adsorbed on the porous means. , Do not leak out of the case without flying again.
This is called a cleaning medium adsorption effect when the opening is opened.

  Although the cleaning medium 5 is a collection of flaky cleaning pieces, it is also used herein as a single flaky cleaning piece.

The ring-shaped internal space 26 of the upper housing 4 </ b> A is a space in which the cleaning medium 5 is accommodated, and a space for the cleaning medium 5 to fly due to the swirling airflow and collide with the object to be cleaned 20 exposed at the opening 18. It is.
The interior 34 of the flow path restriction member 16 is a space where the swirling air current does not act.

A cleaning operation (hereinafter also referred to as “cleaning operation”) by the dry cleaning apparatus 2 configured as described above will be described with reference to FIG.
In FIG. 2, the thickness of the member is omitted, and the interior 34 as a static space is indicated by hatching for easy understanding.
2B shows a state where the opening 18 is separated from the object 20 to be cleaned and the opening 18 is opened to perform intake, and FIG. 2A shows the state where the opening 18 is applied to the object 20 to be cleaned. Indicates a blocked state.
Prior to the cleaning operation, the cleaning medium 5 is supplied into the housing 4.
As a method for supplying the cleaning medium, a predetermined amount of cleaning medium may be sucked from the opening 18 while the suction device 12 is operating, or may be supplied from the inlet 24 while the opening 18 is closed. Good.

The cleaning medium 5 supplied into the housing 4 is sucked by the separation plate 14 and held in the housing 4 as shown in the lower diagram of FIG.
Since the inside of the housing 4 is in a negative pressure state due to intake air, air outside the housing flows into the housing 4 through the inlet 24, but the flow in the inlet 24 at this time is small in both flow velocity and flow rate. The swirling airflow 30 generated in the housing 4 does not reach the strength for causing the cleaning medium 5 to fly.
When the cleaning medium 5 is supplied and held in the housing 4, as shown in FIG. 2A, the opening 18 is put in a closed state by hitting the surface of the cleaning object 20 to be cleaned.

When the opening 18 is closed, the intake from the opening 18 stops, so the negative pressure in the housing 4 increases at a stretch, and the amount of air sucked through the inlet 24 and the flow velocity increase and are rectified in the inlet 24. The
Thereafter, a high-speed air flow is blown out from the inlet outlet (air inlet 22) into the housing 4.
The blown air flow peels off the cleaning medium 5 held on the separation plate 14 and flies toward the surface of the cleaning target 20 exposed at the opening 18.
The air flow becomes a swirling air flow 30 and flows in an annular shape along the inner wall of the housing 4, and a part of the air flow is sucked by the suction means 6 through the hole of the separation plate 14.

When the swirling airflow 30 that has flowed in an annular shape inside the housing 4 returns to the outlet portion of the inlet 24, the airflow entering from the inlet 24 is accelerated while joining the swirling airflow 30.
In this way, a stable swirling airflow 30 is formed in the housing 4.
The cleaning medium 5 swirls (circulates and flies) in the housing 4 by the swirling airflow, and repeatedly collides with the surface of the cleaning object 20.
Due to the impact caused by the collision, the dirt is separated from the surface of the cleaning object 20 in the form of fine particles or powder.
The separated dirt is discharged to the outside of the housing 4 by the suction means 6 through the hole of the separation plate 14.

The swirling airflow 30 formed in the housing 4 has a swirling axis that is orthogonal to the surface of the separation plate 14 and is an airflow parallel to the surface of the separation plate 14.
For this reason, the swirling air flow 30 is sprayed from the lateral direction onto the cleaning medium 5 sucked on the surface of the separation plate and enters between the cleaning medium 5 and the separation plate 14, and the cleaning medium 5 sucked on the separation plate 14 is absorbed. An effect of peeling off from the separation plate 14 and flying again occurs.
Further, since the opening 18 is blocked and the negative pressure in the upper housing 4A increases and becomes close to the negative pressure in the lower housing 4B, the force for sucking the cleaning medium 5 against the surface of the separation plate 14 is also reduced. As a result, the cleaning medium 5 can fly more easily.
Since the swirling airflow 30 is accelerated in a certain direction, a high-speed airflow is easily generated, and a high-speed flying motion of the cleaning medium 5 is also facilitated.
The cleaning medium 5 that swivels at high speed is difficult to be sucked by the separation plate 14, and the dirt attached to the cleaning medium 5 is easily separated from the cleaning medium 5 by centrifugal force.

FIG. 3 shows a practical example of cleaning by the dry cleaning device 2 described above.
The object to be cleaned is a dip pallet used in the above-described flow solder bath process, and is denoted by reference numeral 100.
In the dip pallet 100, mask openings 101, 102, 103 are opened, and the flux FL is deposited and solidified around the holes of the mask openings. This accumulated and solidified flux FL is dirt to be removed.
The base portion (portion of the intake port 8) of the lower housing 4B is grasped with the hand HD, and the opening 18 of the housing 4 is pressed against the portion to be cleaned in the intake state.

Before the opening 18 is pressed against the part to be cleaned, the inside of the housing 4 is sucked and the cleaning medium 5 is sucked by the separation plate 14 (cleaning medium adsorption effect), so the opening 18 faces downward. However, the cleaning medium 5 does not leak from the housing 4 to the outside.
Of course, after the opening 18 is pressed against the site to be cleaned, the inside of the housing becomes airtight, and the cleaning medium does not leak out.

When the opening 18 is pressed against the portion to be cleaned, the inflow airflow from the inlet 24 increases rapidly, a strong swirling airflow 30 is generated in the housing 4, and the cleaning medium 5 sucked by the separation plate 14 is caused to fly.
The cleaning medium 5 collides with the flux FL adhered and solidified on the site to be cleaned of the dip pallet 100, and the flux FL is thereby removed.
As described above, the operator can hold the base of the lower housing 4B in the hand HD, move it with respect to the dip pallet 100, sequentially move the portion to be cleaned, and remove all the adhered and solidified flux FL. .

In the state of FIG. 3, the peripheral portion of the mask opening 101 of the dip pallet 100 is cleaned, and the peripheral portions of the mask openings 102 and 103 are in the process of cleaning.
Even if the opening 18 is separated from the portion to be cleaned when the opening is moved with respect to the portion to be cleaned, the cleaning medium 5 does not leak out of the housing due to the above-described cleaning medium adsorption effect.
For this reason, the number of cleaning media is maintained, and the cleaning performance does not deteriorate due to the decrease in the amount of cleaning media.

During repeated use, the cleaning medium 5 is gradually destroyed by an impact caused by a collision with the cleaning site, and is collected by the suction device 12 together with the flux (dirt) removed from the dip pallet 100 at the site to be cleaned.
For this reason, when the dry cleaning device is used for a long time, the amount of the cleaning medium held in the housing is reduced. In such a case, a new cleaning medium is supplied into the housing 4.

Below, the result of the experiment of the kind of cleaning medium and the cleaning capability will be described.
FIG. 4 is a diagram showing experimental results of the relationship between hardness and fracture toughness of various cleaning media, and FIG. 5 is a diagram showing the characteristics of hardness of various cleaning media.
Fracture toughness is
In FIG. 4, SUS means stainless steel, PC means polycarbonate, PET means polyethylene terephthalate, and PMMA means acrylic.

As shown in FIG. 4, in the present invention, the cleaning medium that falls within the dotted frame is less likely to damage the base material of the object to be cleaned, and the hard film-like dirt that adheres firmly to the surface layer is selectively selected. Identified as a removable cleaning medium.
Specifically, the cleaning medium has a fracture toughness of 1 to 10 [MPa · m ^1/2 ] and a Vickers hardness of 100 Hv [kgf / mm ² ] or more.
The reason will be described below.

[Example 1]
A thin piece of silicon nitride shown in FIG. 6 was used as the cleaning medium. The thickness of the flake is 0.325 mm and the size is 2.5 mm or less.
The dry cleaning apparatus shown in FIG. 1 is filled with 4 g and 6 g of silicon nitride flakes and allowed to fly for 30 sec to obtain a commercially available free-cutting resin (Unilate; trademark, manufactured by Unitika; Rockwell R hardness 120). ) Was peeled off.
A commercially available free-cutting resin corresponds to the object 20 to be cleaned, and corresponds to a hard film-like soil that adheres firmly.
As a comparative cleaning medium, a commercially available melamine shot material (in which melamine resin was granulated) was similarly filled in the casing and peeled off.

FIG. 7 shows the peel weight (scrap amount of commercially available free-cutting resin) by each cleaning medium.
Compared with the melamine shot material, the peeling weight by the silicon nitride flakes is about 4 times, and it can be seen that the cleaning ability against hard film-like dirt is very large.
As shown in FIG. 4, silicon nitride is within a dotted frame, fracture toughness is 1 to 10 [MPa · m ^1/2 ], and Vickers hardness satisfies the condition of 100 Hv [kgf / mm ² ] or more. ing.
Hereinafter, units for fracture toughness and Vickers hardness are omitted as appropriate.

When the silicon nitride thin film having the physical properties in the dotted frame shown in FIG. 4 is used as the cleaning medium, the cleaning medium exhibits a sufficient cleaning ability in the original form (initial shape shown in FIG. 8) during cleaning. As shown in FIG. 9, the cleaning medium is broken and a sharp edge is generated again (recovery of cleaning ability).
This makes it possible to maintain a sufficient cleaning ability for a long time.
If the fracture toughness exceeds 10, the ductility increases, the cleaning medium extends, and the corners and edges of the edges are rounded, resulting in a decrease in cleaning ability.
If the fracture toughness is less than 1, the ductility is too small and the cleaning medium is easily cracked, making it difficult to maintain long-term cleaning capability.
Although the melamine shot material also exhibits a certain level of cleaning ability, it remains at a low level because it is difficult to obtain the biting action by the edge because it is not in the form of flakes.

The thickness of the lamellar cleaning medium is desirably 0.3 to 1.0 mm.
If it is thin, the strength of the newly generated edge is insufficient, and sufficient cleaning ability cannot be expressed. Conversely, if it is thick, it becomes difficult to break, and even if it is cracked, a sharp edge cannot be created and sufficient cleaning ability cannot be expressed.

[Example 2]
In the same manner as in Example 1, the housing of the dry cleaning apparatus was filled with a cleaning medium, and a commercially available wax (File-A-wax manufactured by Ferris; Shore D hardness 55) was peeled off.
Here, the commercially available wax corresponds to the object 20 to be cleaned, and corresponds to a hard film-like stain firmly attached.
As a cleaning medium, a thin piece of silicon carbide having a thickness of 0.8 mm and a size of 3.0 to 5.0 mm was used.
As shown in FIG. 4, silicon carbide is in a dotted frame, has a fracture toughness of 1 to 10, and satisfies the condition that the Vickers hardness is 100 or more.
The comparative cleaning medium is a melamine shot material as in Example 1.

Each peel weight (abrasion amount of commercially available wax) is shown in FIG. The peel weight of the silicon carbide flakes was more than twice that of the melamine shot material.
It can be seen that the cleaning ability of the silicon carbide flakes against hard film-like dirt is large.

[Example 3]
In the same manner as in Example 1, the cleaning medium was filled in the housing of the dry cleaning device, and a commercially available coating film (Misumi's baked paint plate black, melamine baked paint, undercoat electrodeposition coating, coating film thickness 40 μm; pencil hardness 9H ) Was peeled off while moving (scanning) the casing.
The scanning condition was 4 mm / sec, and peeling was performed for 20 sec.
As a cleaning medium, a melamine resin flake by the following production method was used.
Melamine powder (Nikkalet MC CW1076F; manufactured by Nippon Carbide) was compression-molded to produce a melamine sheet having a thickness of 1 mm, and lightly impacted to form fragments. The size is 5.0-10.0 mm.

Here, the commercially available coating film corresponds to the object 20 to be cleaned, and corresponds to a hard film-like stain firmly attached.
The fracture toughness of the melamine resin flakes is 1, and the Vickers hardness is 200.
The comparative cleaning medium is a commercially available acrylic film (fracture toughness 1.2, Vickers hardness 20) having a thickness of 0.125 mm and a size of 3.0 to 5.0 mm.
As shown in FIG. 4, melamine is within a dotted frame (on the line for fracture toughness), fracture toughness is 1 to 10 [MPa · m ^1/2 ], and Vickers hardness is 100 Hv [kgf / mm]. ² ] The above condition is satisfied.
As shown in FIG. 4, acrylic is outside the dotted frame and does not satisfy the above conditions.

The respective peel weights are shown in FIG.
The acrylic film could hardly peel the commercially available coating film, whereas the melamine resin flakes (melamine sheet flakes) showed sufficient peeling performance.
As shown in Examples 1 and 2, melamine has a low cleaning ability in a granular state, but when it is in the form of flakes, it exerts a biting action and exhibits a high cleaning ability.

[Example 4]
In the same manner as in Example 1, the commercially available wax was peeled off.
As a cleaning medium, a thin piece of melamine resin (fracture toughness 1, Vickers hardness 200) was used.
The comparative cleaning medium is quartz glass having a thickness of 1 mm and a size of 5.0 to 10.0 mm. Quartz glass has a fracture toughness of 0.8 and a Vickers hardness of 950.

The peel weight of each cleaning medium is shown in FIG.
As shown in FIG. 4, quartz glass satisfies the condition that the Vickers hardness is 100 or more, but the fracture toughness is less than 1.
When the fracture toughness is less than 1, the cleaning medium is shattered by one collision with the object to be cleaned, and the cleaning ability is lost at a stretch, resulting in the result shown in FIG.
That is, if the fracture toughness is less than 1, the ductility is lowered, so that there is no appropriate shape maintaining property from the formation of an edge with priority to cracking until the next edge is formed, and the cleaning function by the edge does not exist. It becomes shattered soon after it develops.

This also reveals the contribution of the fracture toughness of the cleaning medium to the peel weight (cleaning ability).
In addition, if the fracture toughness is too small, it is easy to break and the cleaning ability is lowered, so it can be seen that there is a lower limit to the fracture toughness in maintaining good cleaning ability.

[Example 5]
The commercially available coating film was peeled off in the same manner as in Example 3.
As a cleaning medium, zirconia having a thickness of 1 mm and a size of 3.0 to 5.0 mm (fracture toughness 7.5, Vickers hardness 1320) was used.
The comparative cleaning medium is a cast iron piece (fracture toughness 15, Vickers hardness 600) having a thickness of 0.5 mm and a size of 3.0 to 5.0 mm produced by cold rolling.

The respective peel weights are shown in FIG.
As shown in FIG. 4, cast iron satisfies the condition that the Vickers hardness is 100 or more, but the fracture toughness is outside the dotted frame.
In cast iron having a fracture toughness of 15, the ductility is too large, and even when the cleaning medium repeatedly collides with the object to be cleaned, the edge is gradually rounded and the edge is gradually rounded, as shown in FIG. Decreases early.
On the other hand, in the case of zirconia, since the fracture toughness is 1 to 10 and the Vickers hardness is 100 or more, the edge is generated by cracking at an appropriate interval, and the cleaning ability is maintained.
This also reveals the contribution of the fracture toughness of the cleaning medium to the peel weight (cleaning ability).
In addition, if the fracture toughness is too large, the cracking is more difficult and the edge becomes round and the cleaning ability is lowered. Therefore, it can be seen that there is an upper limit to the fracture toughness in maintaining good cleaning ability.

[Example 6]
The commercially available free-cutting resin was peeled off in the same manner as in Example 1.
As a cleaning medium, the melamine resin flakes of Example 4 were used.
The comparative cleaning medium is an acrylic film (fracture toughness 1.2, Vickers hardness 20) having a thickness of 0.25 mm and a size of 3.0 to 6.0 mm.

The respective peel weights are shown in FIG.
Acrylic satisfies the conditions of fracture toughness of 1 to 10, but since the Vickers hardness is less than 100, even if the cleaning medium is cracked appropriately and the edge is generated, the teeth are hard against the hard cleaning object. It does not stand, and the cleaning ability falls extremely.
From this, the contribution of the hardness of the cleaning medium to the peel weight (cleaning ability) is clear.
That is, it is clear that the collision strength of the cleaning medium against the sticking dirt depends on the Vickers hardness.
When the Vickers hardness is 100 or more, the edge created by cracking of the cleaning medium has sufficient hardness, so that strong cleaning performance can be exhibited. From this viewpoint, as shown in FIG. 5, aluminum, PC, PET, and PMMA are excluded.

  Other comparative examples are shown below.

[Comparative Example 1]
The commercially available coating film was peeled off in the same manner as in Example 3. The scanning conditions were 2 mm / sec and peeling for 40 sec.
Glass beads (J30; manufactured by Niche; fracture toughness 0.8, Vickers hardness 950) were used as the cleaning medium.
Like quartz glass, the fracture toughness is less than 1, so the cleaning medium is shattered by a single collision with the object to be cleaned, and the cleaning ability disappears all at once.
Further, since the initial shape of the cleaning medium was a sphere, there was no edge, and as a result, the coating film could hardly be peeled off.

[Comparative Example 2]
In the same manner as in Comparative Example 1, the commercially available coating film was peeled off.
As a cleaning medium, a thin piece of SUS304 (fracture toughness 210, Vickers hardness 327) having a thickness of 80 μm and a size of 3 mm was used.
Regarding the cleaning ability, although the initial performance was excellent, the fracture toughness was too large and the edge was rounded, and the deterioration of the cleaning ability was remarkable over time.

[Comparative Example 3]
The commercially available coating film was peeled off in the same manner as in Comparative Example 1.
As a cleaning medium, an aluminum flake (fracture toughness 60, Vickers hardness 86) having a thickness of 0.8 mm and a size of 5 mm was used.
As a result, since aluminum has insufficient hardness as a cleaning medium and has high fracture toughness, the edge is worn away by collision with an object, and the peeling performance to the coating film can be maintained. could not.

  As described above, by using a cleaning medium that falls within a predetermined range based on two physical property values (characteristic values) of fracture toughness and Vickers hardness, it is difficult to damage the base material of the object to be cleaned. It becomes possible to selectively remove hard film-like dirt firmly adhered to the surface layer.

Silicon nitride, a fine ceramic material, has high strength, high heat resistance, high corrosion resistance, and high wear resistance. Silicon nitride substrates used mainly for machine structural parts are highly pure and defect-free. A substrate is used and is very expensive.
The silicon nitride flakes used in the present invention are only limited to a certain thickness and size, and purity and low defects are almost indispensable.
Therefore, it is possible to use a material that has become defective during the production of a ceramic sintered substrate, or that can no longer function as a machine structural component and can be discarded as a recycled material, resulting in a very low material cost. Yeah.
In other words, when the silicon nitride flakes exhibiting excellent cleaning ability against hard film-like dirt are used as the cleaning medium, it is not necessary to obtain an expensive raw material and produce it as a cleaning medium, and waste materials can be used. it can.
It also contributes to the reduction of environmental impact from the point of reuse of waste materials.

  Since the cleaning medium is a consumable item and the running cost is high, the merit of dry cleaning is reduced by half, but such disadvantage can be overcome by using the waste material.

Since a material such as silicon nitride has a needle-like crystal structure, even if it collides with an object to be cleaned and breaks, it does not become powdery but can maintain a needle-like form until the end.
For this reason, since a sharp edge is created, the cleaning ability is continuously maintained until it is discharged together with the removed dirt.
Since the lamellar cleaning medium has an air following ability with respect to the swirling airflow generated in the cleaning device, it easily flies at high speed and collides with dirt with a strong impact force.
At the same time, the action of scraping dirt from the interface at the edge works, so that dirt can be selectively removed without damaging the base material.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to such specific embodiments, and unless specifically limited by the above description, the present invention described in the claims is not limited. Various modifications and changes are possible within the scope of the gist.
The effects described in the embodiments of the present invention are merely examples of the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

DESCRIPTION OF SYMBOLS 2 Dry cleaning apparatus 5 Cleaning medium 6 Air intake means 8 Air inlet 18 Opening part 20 Object to be cleaned 24 Inlet 26 as an air passage 26 Internal space

JP 2012-50973 A

www.tech.nite.go.jp/htdocs/fractdb/Pdf/Shikenhouhou.pdf

Claims (6)

Used to repeatedly hit the object to be cleaned while flying with a swirling airflow,
A cleaning medium having a fracture toughness of 1 to 10 [MPa · m ^1/2 ] and a Vickers hardness of 100 Hv [kgf / mm ² ] or more. The cleaning medium according to claim 1,
A cleaning medium having a flaky shape. The cleaning medium according to claim 1 or 2,
A cleaning medium having a crystal structure of needle-like crystals. The cleaning medium according to any one of claims 1 to 3,
Cleaning media made of ceramic materials. In the cleaning medium according to any one of claims 1 to 4,
A cleaning medium made from recycled materials. An internal space in which the cleaning medium is accommodated;
An opening that communicates with the internal space and contacts the surface to be cleaned;
A ventilation path provided separately from the opening, for introducing external air into the internal space;
An intake port communicating with the internal space and connected to the intake means;
With
The internal space has a shape in which air flowing from the air passage becomes a swirling airflow when sucked by the suction means with the opening being in contact with the surface to be cleaned,
In the dry cleaning apparatus, the opening is arranged so that the cleaning medium flying by the swirling airflow repeatedly collides with the surface to be cleaned.
The dry cleaning apparatus in which the cleaning medium is the cleaning medium according to any one of claims 1 to 5.

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