JPS61152497A - Electrostatic sucker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an electrostatic adsorption device that adsorbs and holds paper, films, etc. using electrostatic adsorption force.

[Prior art 1] In recent years, drawings have been held on drawing boards, recording paper on recording stands, or paper has been held on bulletin boards and various boards using static electricity. ing. Particularly recently, electrostatic holding of objects to be attracted is required in fields such as those in which it is necessary to bring paper into close contact with drawings for designing IC circuits using computer drawings.

Conventionally, electrostatic adsorption devices used for such applications have been integrally formed by embedding or coating the conductor forming the electrode group in an insulating layer, and then thermo-pressing an adsorption layer made of a semiconductor on top of the conductor forming the electrode group. (For example, Torako 54-4
In these conventional electrostatic adsorption devices, the semiconductor adsorption layer is mainly composed of thermoplastic resin and has a specific resistance of 10 as a material that imparts conductivity. It is made of a plastic sheet to which carbon black of about -1Ω-C11 is added. Therefore, the resistance value of the adsorption layer can be adjusted by adjusting the amount of carbon black added, but since the resistance value also changes depending on the amount of other components and the thickness of the sheet, it is possible to obtain a sheet with the desired resistance value. Furthermore, depending on the dispersion state of carbon black, it is difficult to obtain a uniform resistance value over the entire sheet, and it is even easier to obtain a uniform layer with a surface resistance of 1013Ω or more. That's not the point. Furthermore, since the adsorption layer is limited to black color due to the inclusion of carbon black, there is a problem in that there is no choice in terms of the appearance of the product.

[Problem to be Solved by the Invention 1] The present invention adjusts the surface resistance value of the semiconductive sheet that attracts the object to be attracted, and further improves the attraction force of the electrostatic attraction device compared to the conventional one, and Depending on the selection of the material used for the semiconductive sheet, the sheet can be colored in a variety of colors, making it possible to provide a product with a good appearance.

[Means for Solving the Problems 1] In order to achieve the above-mentioned object, the present invention uses a special two-layered structure of a semiconductive sheet that attracts an object to be attracted.

That is, the present invention provides a semiconductive sheet, an electrode disposed in contact with a lower surface of the semiconductive sheet, and a semiconductive sheet.
In an electrostatic adsorption device having an insulating layer to which a sheet and the electrode are integrally fixed, the semiconductive sheet has an upper side layer for performing electrostatic adhesion and a lower side layer in contact with the electrode. The present invention relates to a zero-electromechanical deposition device comprising a plastic sheet having a two-layer structure, wherein the surface resistance value of the upper layer is 10 times or more greater than the surface resistance value of the lower layer.

The most desirable material for the two-layered plastic sheet forming the semiconductive sheet is one obtained by graft copolymerizing a vinyl monomer or vinylidene monomer onto a rubber backbone polymer having a fluorinated oxide group. The antistatic graft copolymer particles are dispersed in a thermoplastic resin matrix, and by forming a sheet with two types of antistatic graft copolymer particles based on the difference in the amount of the antistatic graft copolymer particles added. , it can have a two-layer structure with different surface resistance values.

Thermoplastic resins that serve as a matrix in the above-mentioned polymeric materials include acrylic resin, polyvinyl chloride, A S
It fat, etc. As the antistatic graft copolymer particles dispersed in this matrix, for example,
24364 and Japanese Patent Publication No. 59-2462, it is a monomer of a conjugated diene and/or acrylic ester, a monomer having a fullkylene oxide group, and 1 added as necessary. It is obtained by graft copolymerizing a vinyl monomer or vinylidene monomer by emulsion polymerization or the like to a rubber base polymer obtained by copolymerizing more than one type of copolymerizable vinyl monomer or vinylidene monomer. be.

Since the rubber backbone polymer having a fullylene oxide group in the antistatic graft copolymer acts as a charge carrier and produces an antistatic effect, it is necessary to change the amount of the antistatic graft copolymer added to the thermoplastic matrix. It is possible to obtain polymer materials with different resistance values.

The electrical resistance of the above-mentioned antistatic graft polymer particles having an alkylene oxide group is, for example, a combination of a conjugated tsene and/or acrylic ester monomer and an alkylene oxide group.
By changing the blending ratio of monomers having
Particles with any resistance value in the range of JI can be obtained. Therefore, two or more kinds of polymeric materials having different resistance values can also be obtained by blending antistatic graft polymer particles having different electrical resistance values.

Further, by increasing the amount of vinyl monomer or vinylidene monomer to be graft-polymerized to the rubber base polymer, the resistance value can be controlled to be higher than the volume resistivity value of the rubber base polymer.

Furthermore, in order to obtain a high-resistance plastic sheet using particles with a relatively small volume resistivity value, the amount added is too small, making it difficult to obtain a high-resistance plastic sheet of stable quality. If particles with a large specific volume resistivity are used, the amount added can be increased, and a high-resistance plastic sheet of stable quality can be easily obtained.

In order to obtain a plastic sheet having a two-layer structure with different resistance values used in the present invention, two types of polymeric materials having different amounts of antistatic graft copolymer added are molded by coextrusion or the like.

Experiments have shown that a plastic sheet with a two-layer structure can have a greater adsorption force by making the surface resistance of the upper layer, which attracts the object to be adsorbed, greater than the surface resistance of the bottom layer. did. In order to effectively obtain a large adsorption force, it is necessary that the surface resistance value of the upper surface side layer be 10 times or more greater than the surface resistance value of the lower surface side layer.

A desirable range of surface resistance values is that the surface resistance value of the upper surface side layer is 10 13 to 10 16 Ω, and the surface resistance value of the lower surface side layer is 10 10 to 10 I 3 Ω.

Further, regarding the thickness of the layers, it is desirable that the thickness of the upper surface layer is approximately 1/4 to 1710 times the thickness of the lower surface layer.

FIG. 1 shows an example of an electrostatic adsorption device according to the present invention, and FIG. 2 shows an example of an adsorption layer incorporating a semiconductive sheet and an electrode in the spring-type adsorption device of FIG. 1. 3 is a sectional view, and FIG. 3 is a plan view of the adsorption layer of FIG. 2 viewed from the surface on which electrodes are provided. As shown in the figure, 1 is a semiconductive sheet, and the sheet 1 is made of a plastic sheet having a two-layer structure of an upper layer 2 and a lower layer 3.

Electrodes 4-a and 4-b are arranged in contact with the lower surface of the semiconductive sheet formed as described above. That is, the sheet surface with the smaller surface resistance value is connected to the electrode. The electrodes have, for example, a pair of positive and negative oval-shaped structures so as to form a plurality of capacitors between the electrodes.

In the figure, the electrodes 4-a is a positive electrode and 4-b is a negative electrode are connected to a power supply circuit that can apply a DC voltage between the positive and negative electrodes, and a capacitor is formed between the electrodes by the applied voltage. An electric field is generated in the semiconductive sheet, making it possible to electrostatically attract an object to be attracted to the surface of the sheet.

The comb-shaped planar electrodes 4-a and 4-b are preferably formed by screen printing a conductive paint on the lower surface of the semiconductive sheet.

Screen printing is desirable for the following reasons.

If screen printing is used to form electrodes, it is possible to easily form comb-shaped electrodes in which the electrode shape, dimensions, and distance between electrodes are designed into arbitrary shapes. Since the distance between the positive and negative electrodes and the dimensions of the electrode width can be obtained with extremely high precision, there is an advantage that a large quantity of suction plates with stable quality and a constant suction force can be supplied. On the other hand, with the conventional method of making a comb-shaped electrode from a conductive plastic material or metal foil and thermocompression bonding it to the bottom surface of the adsorption layer, it is difficult to obtain an electrode piece with good dimensional accuracy.
This is difficult in many cases, except when obtaining electrode pieces of relatively large size, and it is even more difficult to position and fix the positive and negative electrode pieces to the bottom surface of the adsorption layer so as to maintain a constant distance between the electrodes. be.

Therefore, the suction force differs from one suction plate to another, making it difficult to supply a large quantity of suction plates that exhibit a constant suction force.

In normal screen printing, conductive paint is coated with a surface resistance of 1
When printing on a sheet surface with a resistance of 015Ω or more, the static electricity generated by the printing roll rubbing against the screen and the electric charge generated by peeling the screen from the sheet surface immediately after printing is completed, cause the unprinted surface of the paint to become MMi-charged. , exerts a strong electrostatic adsorption force on the conductive paint layer immediately after printing, causing the paint to be scattered and adsorbed. Therefore, if left as is, there is a risk that the insulation of the circuit surface that functions as a printed electric circuit or electrode may not be guaranteed.

However, in the case of a sheet having a surface resistance of 10<13 >[Omega] or less, there is no such electrostatic charge, and therefore insulation between the printed electrodes is completely guaranteed. Therefore, when electrodes are formed by printing, it is desirable that the surface resistance of the printed surface be 10<13>Ω or less.

As described above, a structure in which the sheet and the electrode are integrated on one side of the semiconductive sheet is obtained.

The uneven surface of the semiconductive sheet on which the electrodes are formed is fixed to the insulating layer 5, but by performing the fixing with the double-sided adhesive insulating film 6, it can be adsorbed very easily compared to methods such as thermocompression bonding. A plate can be manufactured, and a suction device that requires a suction surface in the shape of a quadratic curve can also be manufactured extremely easily.

An electrode connection hole 7 is provided in the insulator layer 5 and the double-sided adhesive insulating film 6 under one of the positive FIj 4-a and one of the negative electrodes 4-b, and a conductive sealant 8 is provided in the electrode connection hole 7.
A lead wire 9 is buried in the lead wire 9 to connect the positive electrode 4-a and the negative electrode 4-b to the power supply circuit.

In addition, when using the electrostatic adsorption device of the present invention to remove the adsorbed object from the adsorption surface more quickly when the applied voltage between the electrodes is removed, the object to be adsorbed and held by a larger adsorption force can be removed from the adsorption surface more quickly. In order to promote the attenuation of the electrostatic adsorption force, it is desirable to apply a DC voltage in the opposite direction to the DC applied voltage for adsorption and holding. This is possible by connecting the electrodes to a power supply circuit having a secondary circuit that applies a DC voltage in the opposite direction between the electrodes for a short period of time in response to a desorption signal when the applied voltage is cut off.

[Function 1] In the present invention, the semiconductive sheet has a two-layer structure with different surface resistance values, and the surface resistance value of the upper layer that performs electrostatic adsorption is 10% higher than that of the lower layer. By increasing the size by more than twice the size, the upper surface layer can attract the object with a larger attraction force. The reason for this phenomenon is not fully understood, but in a semiconductive sheet with a single composition, opposite charges are generated on the adsorption surface side corresponding to the positive and negative electrodes in contact with the bottom surface of the sheet, which causes the adsorption to occur. This is thought to be due to a phenomenon different from the phenomenon of adsorbing objects.

In addition, it is known that polymeric materials with electrical conductivity due to ion conduction cannot supply ions of the same type from the electrodes, so ions tend to concentrate near the electrodes ([Surface JVo1.13 p367-381 (Sawagobe, "Electrical conduction of polymers"), polymer materials with functional groups such as alkylene oxide groups cause ion concentration around the electrodes, making the charge density at the electrodes extremely high.
It is presumed that the appearance of this concentrated charge increases the electric field strength on the upper surface of the sheet that causes electrostatic adsorption, increasing the adhesion force. Furthermore, it has already been reported that extremely thin polymeric materials exhibit an extremely large dielectric constant in the low frequency range (see above), but a similar phenomenon occurs in the high-resistance layer on the top surface. It is presumed that the effect is further increased.

On the other hand, electron conductors such as carbon plaques do not concentrate electrons because they are supplied with electrons from the electrodes, so when using a conventional plastic sheet containing carbon black as the adsorption surface, the electric field on the adsorption surface It is thought that the strength does not have any particular increasing effect and depends on the capacitor *ffi formed by the electrodes arranged on the bottom surface of the sheet.

This is based on the following examples and comparative example 1, in an adsorption plate (adsorption surface resistance 1012Ω) whose adsorption layer is an actually commercially available PVC sheet filled with carbon black (10%). The capacitor capacity is 50 pF, and the adsorption force for A-4 size recording paper is 2.
．． IKg (42g per 1pF), whereas in the adsorption layer of the present invention (adsorption surface resistance 1014Ω), the adsorption force is 14.5Kg (1pF) at a capacitor capacity of 112pF.
129.5 y per F), and a layer sheet (surface resistance 1012
), but the capacitor capacity is 112pF and the adsorption force is 6.5Ky.
(581F per pF).

[Example and Comparative Example 1 (a) Preparation of semiconductive sheet 42 parts of octyl acrylate, 10 parts of styrene, 8.8 parts of methoxypolyethylene glycol methacrylate, polyethylene glycol dimethacrylate) 4.2 parts to 2 parts
Methyl methacrylate 35 is added to the step-polymerized rubber backbone polymer.
A white antistatic graft copolymer with an average particle diameter of 0.08 μ and a volume resistivity of 108 Ω-cm was obtained by graft copolymerizing a commercially available acrylic resin (Sumipek ■B- manufactured by Sumitomo Chemical Co., Ltd.).
MHG) was mixed in a blender with the 5 types of formulations shown in Table 1 to obtain 5 types of molding powders. The lower column of Table 1 shows the surface resistance values of sheets with thicknesses ranging from 0.8 x m to 1.2 yzz obtained by press-molding these powders at 200° C. and 200 Kg/cm 2 .

Next, these compounds were extruded using two machines (112φ
ABCDEFG shown in Table 2 was produced using a two-layer sheet extruder connected to a feed block (L/D=20.50φL/D=2.6) and a 1150zi+width T-Guy.
Seven types of semiconductive plastic sheets were manufactured. F,
G is a comparative example of Shishito G is compound ■ added with an inorganic pigment and colored in an eye poly color at 0.5 a.
It is made into a single layer sheet with x thickness.

The extrusion conditions are T in terms of temperature to obtain any sheet.
-Cylinder temperature in the range of 190℃ to 230℃ so that the resin temperature at the gooey outlet is maintained at 235℃, feed block temperature to 230℃, T-gooey temperature to 225℃$I
Extrusion was performed while adjusting.

C) When obtaining A, C, and E, compound I is 50φ
Using an extruder with a screw rotation of 10 rp, it is pounded.■
was extruded using a 112φ extruder with a screw rotation of 35 rpm*. The discharge amount is 10 Ky/Hr for a 50φ extruded rock.
The 112φ extruder is 90KlF/Hr.

C) In the case of B, molding was carried out by reducing the screw rotation speed of only the 112φ extruder and setting the discharge rate to 40 KFI/Hr.

C) D has a discharge rate of 30K from a 50φ extruder.

/Hr, the discharge rate of the 112φ extrusion was adjusted to 70K, and the screw rotation was adjusted.

To obtain C) F and G, sheets were formed using only a 112φ extruder at a discharge rate of 97 Kg/Hr (screw rotation 40 pm).

The measured thickness and upper and lower surface resistance values of each sheet obtained are shown in Table #S2. Note that C) F and G exhibited the same surface resistance value on both the upper and lower surfaces.

The surface resistance value of each sheet was measured using a simple measuring device compliant with ASTM or a commercially available cell-type resistance measuring device (Super Megohmmeter 5M-
5E (manufactured by Toa Denpasha).

(b) Creation of suction plate The seven types of sheets obtained are A-4 size (length 278, 5J).
IJI, 1ii225zz), and electrodes were printed on the lower surface of each sheet. As a comparative example, sheets A and C were also created with electrodes printed on their upper surfaces in order to create suction plates that were turned upside down.

To print the electrodes, use a silk screen with a pattern so that an electrode pair with a distance of 5 μm and a distance of 5 μl between the positive and negative electrodes is formed. Roll printing was performed using a paint diluted by 50%, and the paint was immediately placed in a hot air drying oven to cure the paint. The thickness of the printed electrodes was 10-15 μl.

Next, in order to connect the positive and negative poles of the electrodes printed on the sheet in advance to a DC power source, a commercially available PVC board with a thickness of 3.5 pm was provided with holes of 5 ag diameter at the positions determined by the shape of the electrodes. double-sided adhesive film (double-sided adhesive tape No.
501M (manufactured by Nitto Denko) was attached, and after removing the film covering the hole positions, the printed surfaces of the respective sheets with electrodes printed thereon were adhered thereon. Pinch rolls were used for adhesion to prevent air pockets on the adhesion surface.

Next, a conductive adhesive silicone sealant (Shin-Etsu Silicon 9I

For comparison, when sheet A was turned upside down and printed on the top surface, when the screen was peeled off from the sheet during printing, the conductive paint scattered and adhered to the surface between the electrodes where no printing was performed. This was recognized. In addition, a slight amount of this scattering was observed when printing on the top surface of Sheet C, but it was not observed at all in other cases. When printing on a PVC board, even more severe scattering and adhesion was observed, and it was determined that the cause of this phenomenon was the effect of static electricity caused by peeling and charging between the screen and the sheet.

(c) Measurement and evaluation of suction force Place the suction plate obtained as above on a horizontally supporting table, connect the lead wire to a DC power source, and place a commercially available A-4 version record on the suction surface. A sheet of paper (recording paper for X-Y recorders, sold by Gra7 Take Co.) was placed and the suction force was measured. To measure the suction force, we used a commercially available needle-type tension deno (manufactured by Tenba Keiki Seisakusho) with a maximum load of 20 mm on a screw-driven 7-meter that pulls out the recording paper in a direction parallel to the suction surface, and a recording paper at the tip. A pull-off test machine was prepared, in which a metal rod equipped with a chuck with a grip width of 501R was connected, and a slide device was installed to support the horizontal movement of the spring gauge and the metal rod.

The conditions for measuring the suction force were to place the recording paper on the suction plate, put it in the chuck, remove the air from the paper and the suction surface with a roll, and then apply a DC voltage of 600 V between the suction plate electrodes. , After 2 minutes, operate the take-up test machine and increase the take-up speed to 1.
The recording paper that had been sucked at 8 z1 minute was taken out, and the maximum stress indicated on the spring scale was read and determined as the suction force.

Table 3 shows the suction powers of the suction plates manufactured using the various sheets thus obtained.

Note that the commercially available adsorption plate is a PVC-based adsorption plate to which it is estimated that about 10 parts of carbon black is added, and the thickness of the adsorption layer is about 0.51.

Furthermore, among the suction plates on which the suction force was measured, the capacitance of the suction plate used for #S1 measurement was measured for the one using C1G and four commercially available suction plates of three types. The capacitance was measured using a C0R meter (manufactured by NC Circuit Design Co., Ltd.), with the measuring device and suction plate placed on an aluminum plate of 70 cdll with a thickness of 5 IM. The measurement results are shown in Table 4 in comparison with the adsorption force.

That is, an adsorption sheet made by printing a pair of positive and negative comb-shaped electrodes on the surface of the semiconductive sheet having a two-layer structure of the present invention with low surface resistance is fixed to an insulating layer using a double-sided adhesive insulating film. The resulting electrostatic adsorption device exhibited stronger power outage adsorption power than expected.

In contrast to the conventional adsorption device that uses a single-layer structure semiconductive plastic sheet as the adsorption layer, the technical idea was to improve the adsorption force simply by increasing the capacitance of the capacitor formed by a pair of positive and negative comb-shaped electrodes. We focused on the suction power per unit capacity, which had not received any attention until now.
Surprisingly, it was found from the above measurements that the adhesion force per unit capacity obtained with a single-layer semiconductive sheet can be more than doubled at once.

[Effect of the invention 1 According to the electrostatic adsorption device of the present invention, due to the above-mentioned action,
It is possible to generate a very large adsorption force, and it is possible to strongly hold an object to be adsorbed.

In addition, as a material for the semiconductive sheet, antistatic graft copolymer particles obtained by graft copolymerizing a vinyl monomer or vinylidene monomer to a rubber backbone polymer having a fullkylene oxide group are thermoplastic resins. M) By using a polymeric material dispersed throughout the body, it is easy to apply various colors and it is possible to obtain a product with the desired appearance. Furthermore, such polymeric materials have the effect of increasing the electric field strength on the adsorption surface due to the concentration of electrons.

In addition, if screen printing is used to form electrodes, it is possible to easily form comb-shaped electrodes with arbitrary electrode shapes, dimensions, and distances between electrodes, and the distance between positive and negative electrodes and the dimensions within the electrodes can be easily formed. Since it can be obtained with extremely high precision, it has the advantage of being able to supply a large amount of stable quality @deposited plates that exhibit a constant adsorption force.

Furthermore, by using a semiconductive plastic sheet printed with electrodes as the suction surface and using a double-sided adhesive insulating film as the support insulator, it is possible to easily obtain a suction device having a quadratic curved suction surface. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the electrostatic adsorption device of the present invention, and FIG. 2 is a cross section of an adsorption layer in which the semiconductive plastic sheet and electrode of the electrostatic adsorption device of FIG. 1 are integrated. Figure 3 is a front view of the adsorption layer in Figure 2 viewed from the side where the electrodes are arranged;

Claims (5)

[Claims] (1) In an electrostatic adsorption device having a semiconductive sheet, an electrode disposed in contact with the lower surface of the semiconductive sheet, and an insulating layer to which the semiconductive sheet and the electrode are fixed together. , the semiconductive sheet is made of a plastic sheet having a two-layer structure including an upper side layer for electrostatic adsorption and a lower side layer in contact with the electrode, and the surface resistance value of the upper side layer is higher than that of the lower side layer. An electrostatic adsorption device characterized in that the surface resistance value is 10 times or more greater than the surface resistance value of the electrostatic adsorption device. (2) The two-layer plastic sheet constituting the semiconductive sheet is an antistatic graft copolymer obtained by graft copolymerizing a vinyl monomer or vinylidene monomer to a rubber backbone polymer having an alkylene oxide group. Consisting of a polymeric material in which polymer particles are dispersed in a thermoplastic resin matrix,
Claim 1, wherein the antistatic graft copolymer is formed into a two-layer structure by adding two different amounts of the antistatic graft copolymer.
The electrostatic adsorption device described in section. (3) The surface resistance value of the upper layer of the semiconductive sheet is 10^
1^3 to 10^1^6Ω, and the surface resistance value of the lower side layer is 10^1^0 to 10^1^3Ω. . (4) The electrostatic device according to claim 1, wherein the electrode disposed in contact with the lower surface of the semiconductive sheet is formed by printing a conductive paint on the lower surface of the semiconductive sheet. Adsorption device. (5) The electrostatic adsorption device according to claim 4, wherein the electrode printed surface of the semiconductive sheet and the insulating layer are fixed by a double-sided adhesive insulating film.