JP2002244562A - Magnetic attraction sheet - Google Patents

Abstract

(57) [Problem] To provide a magnetic attraction sheet for display which suppresses surface electric resistance and does not cause double feeding due to generation of static electricity during printing. SOLUTION: This is a magnetic attraction sheet 1 in which a recording layer 5 is provided on a first surface 1a of a nonmagnetic support 3, and a magnetic attraction layer 7 is provided on a second surface 1b. Is provided with an antistatic layer 9 in which carbon particles are dispersed in a binder resin. The antistatic layer 9 has an average film thickness of 0.
5 to 3.5 μm, and the carbon particles have an average particle diameter of 0.3 to 2.0 μm. The antistatic layer 9 contains 85 to 10 parts by weight of a binder resin based on 100 parts by weight of the carbon particles.
It is contained in a proportion of 0 parts by weight. Further, a pigment having an average particle size of 4 to 20 μm may be dispersed in the antistatic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic attraction sheet, and more particularly, to a magnetic attraction sheet suitably used as various display devices.

[0002]

2. Description of the Related Art At present, a magnetic attraction sheet utilizing the magnetic attraction of a permanent magnet is formed by forming a magnetic layer on a non-magnetic support, and is widely used as various display devices, especially as office supplies. Applications are expanding. In this magnetic adsorption sheet, since the display object itself is a fixing material having a magnetic adsorption property, when the presentation place is a ferromagnetic surface, various adhesives,
The display object can be posted alone without the need for a fixing material such as an adhesive tape, a thumbtack, or a cap magnet.

[0003] In recent years, with the rapid spread of personal computers, the performance of peripheral devices such as printers has been remarkably improved, and the quality of printing by general-purpose printers has become comparable to that of commercial printing. At the same time, there is a growing desire to freely use those printed materials.

[0004] In response, the above-mentioned magnetic attraction sheet has been reduced in thickness so that it can be used in general-purpose printers and the like, and a mixture / kneaded product of ferromagnetic powder and a polymer binder is extruded into a thin film. By molding or compression molding, a total thickness of 0.2 mm to 0.3 mm and a magnetic layer thickness of 0.08
It is possible to provide a magnetic attraction sheet having a thickness of 0.2 mm to 0.2 mm. Furthermore, a magnetic paint mainly composed of a ferromagnetic powder and a polymer binder is coated on a non-magnetic support, oriented,
A magnetic coating film is formed by drying, and an in-plane multipolar magnetization is applied, so that the total thickness is 0.08 mm to 0.25 m.
m, a magnetic layer thickness of 0.03 mm to 0.15 mm, a thin film equivalent to that of ordinary printing paper, and a magnetic attraction sheet that can be printed by a general printer or the like can be provided.

As described above, the magnetic attraction sheet can be printed by using various printing machines such as a commonly used copying machine, an IJ printer, a thermal transfer printer, a sublimation printer, and a laser printer. Not only can you print out and post images taken with scanners, etc., images taken with a scanner, etc., but also calendars, cooking recipes, schedules, posters (for elections, department stores, trains, etc.) that are freely processed by yourself. Also prints beginner marks, photos, etc. of cars, without using various adhesives, adhesive tapes, thumbtacks, fixing agents such as magnets on ferromagnetic surfaces such as refrigerator doors and walls, whiteboards for magnets, streets, etc. It is possible to post.

[0006]

However, the magnetic attraction sheet as described above has a magnetic layer surface having a surface electric resistance of 1E + 9.
Since it is too high (10 ⁹ ) or more, static electricity is easily generated, and the electrostatic adhesion between sheets is large. For this reason, problems such as a decrease in running properties such as double feeding during printing and a problem that a magnetically attracting sheet processed at the time of processing with scissors or the like is stuck to clothes or a human body are likely to occur.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetic attraction sheet for display which suppresses surface electric resistance and prevents double feed due to generation of static electricity during printing.

[0008]

According to the present invention, there is provided a magnetic attraction sheet having a magnetic attraction layer provided on a non-magnetic support.
It is characterized in that an antistatic layer formed by dispersing carbon particles in a binder resin is provided. This antistatic layer has an average thickness of 0.5 to 3.5 μm.

In the magnetic attraction sheet having such a structure, since the antistatic layer containing carbon particles is provided on the surface of the magnetic attraction layer, the magnetic attraction layer side (that is, the magnetic attraction layer side with the nonmagnetic support interposed therebetween) is provided. And the charge on the antistatic layer side) is prevented. In this case, particularly, the average film thickness of the antistatic layer is set to 0.1.
By setting the thickness to 5 to 3.5 μm, the magnetic attraction force on the attraction surface (the surface of the antistatic layer) is maintained, and the entire surface of the attraction surface is prevented from being charged satisfactorily without causing uneven coating of the antistatic layer. can do.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magnetic attraction sheet of the present invention will be described below in detail. FIG. 1 is a schematic cross-sectional view of the magnetic attraction sheet of the present embodiment, and FIG. 2 is an enlarged cross-sectional view of a main part in FIG. However, FIG. 1 and FIG. 2 are upside down.

The magnetic attraction sheet 1 shown in these figures is a thin-film magnetic attraction sheet that can be printed by a general home copying machine or a printer, etc., and has one main surface (first surface) of the nonmagnetic support 3. On top of 3a), a recording layer 5, which is a printing ink receiving layer, is provided. On the surface (second surface 3b) of the non-magnetic support 3 opposite to the surface on which the recording layer 5 is provided, a magnetic attraction layer 7 is provided. An antistatic layer 9 unique to the present invention is provided.

Next, details of each layer constituting such a magnetic attraction sheet 1 will be described.

<Non-Magnetic Support> As the non-magnetic support 3, for example, a white polyester film having a surface subjected to an easy adhesion treatment is used. In addition, the non-magnetic support 3
For the purpose of coating and forming the magnetic adsorption layer 7 on the second surface 3b, it is preferable to use resin-coated paper, synthetic paper, white synthetic film, or the like that is not coated with a solvent on the back side of the coating surface. Can be used.

<Recording Layer> As the recording layer 5, a receptor layer according to a printing method such as a heat-sensitive layer, a thermal transfer ink receiving layer, an ink jet receiving layer, a bubble ink jet receiving layer, a dot impact receiving layer, a laser printer toner receiving layer, or the like is used. A receiving layer which can be applied and has a function corresponding to a display purpose and a printing method is appropriately selected and used.

<Magnetic Attachment Layer> The magnetic attraction layer 7 is formed by applying a magnetic paint in which a ferromagnetic powder is dispersed in a binder resin onto the non-magnetic support 3 and drying it. It is multipolar magnetized as shown.

Examples of the ferromagnetic powder constituting the magnetic adsorption layer 7 include ferromagnetic iron oxides such as Ba ferrite powder and Sr ferrite powder, and Sm-Co powder, Sm-Fe-N powder, Nd Rare earth ferromagnetic materials such as -Fe-B powder. As the binder resin for dispersing such ferromagnetic powder, thermoplastic and thermosetting resins are used. Among them, resins preferably used include epoxy resins, ethylene vinyl acetate copolymers, ethylene vinyl acetate block copolymers,
Copolymers of ethylene and (meth) acrylate, block copolymer polyethylene, acrylic resin, polyester resin, polyurethane resin, and the like can be used. These resins can be used alone or in combination of several kinds. good. In addition, it is assumed that additives are added to the magnetic adsorption layer 7 as needed in addition to the ferromagnetic powder and the binder resin.

<Antistatic Layer> As shown in FIG. 2, the antistatic layer 9 is formed by dispersing carbon particles 93 and, if necessary, other pigments 95 in a binder resin 91. It is obtained by applying the antistatic paint mixed therein to the magnetic adsorption layer 7 and drying. Further, in addition to the binder resin 91, a cellulose acetate resin or silicone oil serving as an anti-adhesive may be added to the antistatic layer 9.

Here, the thickness of the antistatic layer 9 is preferably 0.5 to 3.5 μm, more preferably 1 to 2 μm in average film thickness. Here, when the surface on the recording layer 5 side is the recording surface 1a and the surface on the antistatic layer 9 side is the adsorption surface 1b, the surface electric resistance value of the adsorption surface 1b is preferably less than 1E + 9 (Ω). . If it is larger than this, the suction surface 1
b easily generates static electricity, the electrostatic adhesion increases,
Double feed may occur during printing, or sheets may stick together during processing with scissors, etc. (sticking between sheets and clothing,
Workability becomes worse. For this reason, it is assumed that the carbon particles 93 are added to the antistatic layer 9 having the above average film thickness so that the surface electric resistance of the adsorption surface 1b is less than 1E + 9 (Ω).

As the binder resin 91, polyurethane resin, nitrocellulose resin, polycarbonate resin, polyester resin, epoxy resin, vinyl chloride, vinyl acetate, vinyl alcohol, vinylidene chloride,
Examples thereof include polymers such as acrylic acid esters, methacrylic acid esters, styrene, butadiene, and acrylonitrile, and copolymers obtained by combining two or more of these. The ratio of the binder resin 91 in the antistatic layer 9 is 85 to 100 with respect to 100 parts by weight of the carbon particles.
It is preferably in parts by weight.

The carbon particles 93 have an average particle size of 0.1.
It is 3 to 2.0 μm. In addition, carbon particles 9
As specific examples of No. 3, for example, thermal black (manufactured by Kahn Carb Co., trade name), RAVEN MTP (manufactured by Columbia Carbon Co., trade name) and the like can be used.

The pigment 95 is dispersed in the antistatic layer 9 for the purpose of preventing friction between sheets. Here, the coefficient of friction (μ) between sheets of the magnetic attraction sheet 1 is preferably 0.25 or less, and more preferably 0.20 or less. If it is larger than 0.25, the sheets will not slip easily, and there is a possibility that double feed may occur during printing. The coefficient of friction (μ) between papers is 0.1
Desirably, it is 0 or more. If it is less than 0.10, it becomes difficult to feed the magnetic attraction sheet 1 to a printing device. Therefore, a pigment 95 having an average particle size of 4 to 20 μm can be added to the antistatic layer 9 so that the coefficient of friction between sheets can be suppressed. Examples of such a pigment 95 include organic pigments such as nylon and rubber, and inorganic pigments such as silica, alumina and titanium oxide. The proportion of the pigment 95 in the antistatic layer 9 is
The amount is preferably 5 to 20 parts by weight with respect to 0 parts by weight.

As the cellulose acetate resin added as an antiadhesive, for example, cellulose acetate butyrate (CAB) can be used. The addition amount of the cellulose acetate resin is 50 to 75 parts by weight based on 100 parts by weight of carbon.

When silicone oil is added as an antiadhesive, 0.5 to 1 part by weight of silicone oil is added to 100 parts by weight of carbon.

Next, an example of a method for manufacturing the magnetic attraction sheet having the above-described configuration will be described.

First, an appropriately selected nonmagnetic support 3 is prepared, and an appropriately selected recording layer 5 is formed on the first surface 3a by a known technique.

Thereafter, a magnetic coating material in which ferromagnetic particles are sufficiently dispersed in a binder resin and a solvent is prepared, and the magnetic coating material is coated with a gravure coater, a die coater, a knife coater or the like on the second surface of the nonmagnetic support 3. 3b. Next, the non-magnetic support 3 coated with the magnetic paint is introduced into and passed through an orientation magnetic field, thereby orienting the axis of easy magnetization of the ferromagnetic powder in the magnetic paint. Furthermore, the non-magnetic support 3 is introduced into and passed through hot air supplied from a hot-air dryer, thereby evaporating the solvent in the magnetic paint. Thus, the magnetic paint is dried and solidified without using high-temperature and high-pressure equipment such as extrusion molding, and the multi-polar magnetized thin-film magnetic adsorption layer 7 is continuously formed.

Next, using a disper or a ball mill,
Carbon particles 93 and pigment 95 in the binder resin 91 and the solvent
To prepare an antistatic paint in which is dispersed sufficiently. Then
Gravure coater, die coater,
The antistatic layer 9 is formed by applying a predetermined thickness on the magnetic attraction layer 7 using a knife coater or the like, drying the coating, and then performing multipolar magnetization.

The magnetic adsorbing sheet 1 having the above structure obtained as described above has a carbon particle 9 on the surface of the magnetic adsorbing layer 7.
Since the antistatic layer 9 containing 3 is provided, static electricity is prevented from being generated on the adsorption surface 1b due to charging.

In particular, when the average thickness of the antistatic layer is 0.5 to
Since the thickness is 3.5 μm, the magnetic attraction layer 7 and the attraction surface 1b
, While maintaining the magnetic attraction force on the attraction surface 1b while maintaining a small gap between the attraction surface 1b and the surface of the attraction surface 1b. . Moreover, the antistatic layer 9
If the film thickness exceeds 3.5 μm, cracks may occur in the antistatic layer 9 due to deformation of the magnetic attraction sheet 1 during use, and the antistatic layer 9 itself may be destroyed. It is also possible to ensure durability.

The average particle size of the carbon particles 93 is set to 0.1.
By setting the thickness to 3 to 2.0 μm, the carbon particles 93 can be reliably retained in the antistatic layer 9 while the dispersibility of the carbon particles 93 in the antistatic layer 9 is ensured, and printing during printing can be performed. It is also possible to prevent the carbon particles 93 from falling off by friction with the paper feed mechanism of the printer. In addition, the retention of the carbon particles 93 in the antistatic layer 9 is also ensured by ensuring the dispersibility.

Further, the ratio of the binder resin 91 in the antistatic layer 9 was determined based on 100 parts by weight of the carbon particles.
By setting the amount to 85 to 100 parts by weight, the carbon particles 93 can be sufficiently held by the binder resin 91, which can prevent the carbon particles 93 from falling off during printing, and Agent resin 91
The amount is suppressed, and the adhesion resistance of the suction surface 1b is also ensured.

The pigment 9 added to the antistatic layer 9
5 has an average particle size of 4 to 20 μm, thereby ensuring the retention of the pigment 95 in the antistatic layer 9 and the absorption surface 1.
By making the surface roughness b sufficiently large, the coefficient of friction between sheets of the magnetic attraction sheet 1 can be further reduced. For this reason, it is possible to reduce the friction between sheets when the magnetic attraction sheet 1 is printed, and to reduce the probability of double feeding during printing. Moreover, by increasing the roughness of the surface of the antistatic layer 9 by adding the pigment 95, the adhesion of the magnetically attractable sheets 1 can be prevented.

The content of the carbon particles 93 in the antistatic layer 9 was adjusted by adding 50 to 75 parts by weight of the additive of the cellulose acetate resin in the antistatic layer 9 with respect to 100 parts by weight of carbon. It is possible to obtain the antistatic effect by maintaining the ratio and the antistatic effect by the cellulose acetate resin while obtaining the antistatic effect.

Further, by setting the additive amount of the silicone oil in the antistatic layer 9 to 0.5 to 1 part by weight with respect to 100 parts by weight of carbon, it is possible to suppress the decrease in the adhesion resistance due to the precipitation of the silicone oil. In addition, the anti-adhesion effect of the silicone oil can be obtained.

As described above, since the surface electric resistance of the suction surface 1b and the friction between the sheets can be reduced,
The running property of the magnetic attraction sheet when printing with various general copying machines and printers such as an IJ printer, a thermal transfer printer, a sublimation printer, and a laser printer can be improved. As a result, even when printing is performed, printing can be performed without causing double feeding due to frictional charging and sheet friction between sheets.

Further, since the antistatic layer 9 serves as a protective film for the magnetic attraction layer 7, even when a general printer or the like is used, the pigment adheres to the surface of the magnetic attraction layer 7 due to friction with the paper feed mechanism of the printer. (Ferromagnetic powder) can be prevented from falling off. This makes it possible to maintain the magnetic attraction even during long-term use.

Further, since the suction surface 1b has excellent resistance to powder falling, continuous printing can be performed by a general copying machine or printer.

Furthermore, because of its excellent anti-adhesion property, even if it is adsorbed on a surface to be heated such as a pot or the like which is heated for a long period of time, the adhesion between the adsorption surface 1b of the magnetic adsorption sheet 1 and the surface to be adsorbed. Can be prevented.

Such a magnetically attracting sheet 1 can be applied to a self-made calendar, a self-made recipe, a schedule table, photographs, posters such as posters, a wallpaper, and a car mark (beginner mark, etc.). Continuous printing by a printing device is possible, and posting for a long time is possible.

[0040]

EXAMPLES Hereinafter, specific examples 1 to 15 of the magnetic attraction sheet 1 to which the present invention is applied, comparative examples 1 to 16 for these examples, and evaluation results thereof will be described. Here, with respect to the magnetically attracted sheets prepared in Examples 1 to 15 and Comparative Examples 1 to 16, respective evaluation tests on the following items were performed.

<Surface Electric Resistance> Surface electric resistance measuring device M-
The surface electric resistance (Ω) of the adsorption surface (the surface on the side of the magnetic adsorption layer via the nonmagnetic support) was measured by 308 [manufactured by Shisido Electrostatic Co., Ltd.]. In order to prevent double feeding of the magnetically attracting sheet during printing and to improve the printing workability, the allowable value of the surface electric resistance (Ω) is less than 1E + 9 (10 ¹⁹ ).

<Paper friction> The coefficient of friction between paper (μ) between the recording surface and the attracting surface of the magnetic attracting sheet was determined by a Haydon friction meter (Tribogear TYPE: HEIDON-14DR, manufactured by Shinto Kagaku Co., Ltd.). Was measured as follows. First, the recording surface of the magnetic attraction sheet is fixed on the sample table so that the recording surface is turned upside down.
The magnetic adsorption sheet cut into cm is wound so that the adsorption surface is turned upside down, and is overlaid on the recording layer surface on the sample table. A 1kg weight is placed on top of it, and the tool on the suction surface side is 150mm / m
in. , And record the friction coefficient (μ) (kinetic friction coefficient) between the sheets at that time. The inter-sheet friction coefficient measured in this manner is desirably 0.25 or less in order to prevent double feeding of the magnetically attracting sheet during printing.
0.20 or less is more preferable.

<Blocking (adhesion resistance)> The prepared magnetic adsorption sheet was cut into 8 cm x 8 cm, and the magnetic adsorption sheet adsorbed to the metal cabinet and the magnetic adsorption sheet adsorbing the adsorption surfaces were kept at a constant temperature. Bath (temperature 45
(° C., humidity: 75%) for 7 days to confirm the presence or absence of adhesion. Those having no adhesion were designated as OK products (（), and those having adhesion were designated as NG products (×).

<Dust resistance> 100 with IJ printer (Calario PM-3000C: Seiko Epson)
After printing, printing was performed on plain paper, and it was confirmed that the printed plain paper was free from carbon particles, magnetic powder, and other stains caused by pigments. Those with no stain were regarded as OK products (（), and those with stains were regarded as NG products (×).

<Magnetic Attraction Force> The magnetic attraction sheet is 100 m
It was cut out to mx 100 mm, a resin plate of the same shape as the sheet was attached to the recording surface side with an adhesive, and it was fixed horizontally.
The magnetic force was magnetically attracted onto a 5 mm thick steel sheet, and the minimum peeling force when peeling vertically above the steel sheet was measured with a spring balance. From this peeling force, the magnetic attraction force was calculated as in the following equation (1). Magnetic attraction force = {peeling force-(sheet weight + adhesive weight + resin plate weight)} / sheet area

Here, the magnetic attraction force of the permanent magnet can be magnetically attracted to a vertical surface in a stationary state if the attraction force is three times or more of its own weight empirically. Impact, wind pressure in indoor air conditioning, etc.). 1 of own weight
It is said that if it has a magnetic attraction force of 0 times or more, it can be stably attracted to disturbance. Therefore, when the sheet weight (weight) is 1, the magnetic attraction force of 10 or more is an allowable value.

<Adhesive Strength> A silicone tape was adhered to the attracting surface side of the magnetic attracting sheet, and it was confirmed whether or not peeling occurred in the antistatic layer immediately after attaching and after 30 minutes had passed and the silicone tape was peeled off. Those without peeling were regarded as OK products (（), and those with peeling were regarded as NG products (×).

Hereinafter, the respective examples and comparative examples and evaluation results thereof will be described.

Example 1 First, a recording medium a in which a recording layer composed of an ink jet-compatible receiving layer was provided on a first surface of a nonmagnetic support composed of white synthetic paper was prepared. The thickness of the recording medium a is
The thickness was 0.08 mm.

Further, according to the composition shown in Table 1 below, the magnetic powder, the binder resin, and the solvent were mixed by a ball mill and uniformly dispersed to prepare a magnetic paint. The curing agent (Coronate HL: manufactured by Nippon Polyurethane) was added after mixing other materials.

[0051]

[Table 1]

Next, a magnetic paint having the composition shown in Table 1 was applied to the second surface of the nonmagnetic support 3 by a gravure coater, and then passed through an in-plane orientation magnetic field of 2 kG due to the same polarity of a permanent magnet. After the in-plane orientation was performed, the substrate was dried to obtain a raw film.
The obtained raw material is stored in a 60 ° C. environment for 20 hours or more and subjected to a curing treatment, so that a film thickness of 0.0
A 5 mm magnetic attraction layer was formed, and this was used as a sheet b.
The total thickness of this sheet b was 0.13 mm.

On the other hand, according to the composition shown in Table 2 below, a binder resin, carbon particles, a solvent, and cellulose acetate butyrate (CAB) were mixed by a ball mill and uniformly dispersed to prepare an antistatic paint.

[0054]

[Table 2]

Thereafter, the sheet b
Was coated with an antistatic paint on the magnetically adsorbing layer, and the applied film was dried to form an antistatic layer. When applying the antistatic paint, the thickness of the antistatic layer is 1 to
It was adjusted to 2 μm.

After the above, the magnetic attraction layer was subjected to multipolar magnetization (magnetization width 2.0 mm), thereby producing a magnetic attraction sheet having an antistatic layer provided on the magnetic attraction layer.

Examples 2 to 4 Magnetic adsorption sheets were prepared in the same manner as in Example 1, except that the average film thickness (coating thickness) of the antistatic layer was changed as shown in Table 3 below.

Comparative Example 1 Sheet b before forming the charged coating layer in Example 1 was directly used as a magnetically attractable sheet.

Comparative Example 2 A polyurethane resin (polyurethane resin MG0130 manufactured by Toyobo Co., Ltd.) having a thickness of 1.0 μm was applied on the magnetically adsorbing layer of the sheet b in Example 1 in place of the antistatic layer, and magnetically adsorbed. Sheet.

Comparative Examples 3 to 5 Magnetically attractable sheets were produced in the same manner as in Example 1 except that the average film thickness (coating thickness) of the antistatic layer was changed as shown in Table 3 below.

[0061]

[Table 3]

(Evaluation Results) Examples 1 and 2
Each of the evaluation tests described above was performed on the magnetic attraction sheets manufactured in Comparative Example 4 and Comparative Examples 1 to 5, and the evaluation results were displayed according to Table 3.

As is clear from Table 3, in Comparative Example 1 in which the antistatic layer was not provided and in Comparative Example 2 in which only the urethane resin was applied on the magnetically attracting layer, the surface electric resistance was 1E.
+3 (10 ¹³ ) or more, and cannot prevent double feeding during printing due to charging. In Comparative Example 1, since the magnetic adsorption layer was exposed, powder fell off of the ferromagnetic powder.

The average thickness of the antistatic layer is 0.5 μm.
In Comparative Example 3, which is less than m, the surface of the magnetic attraction layer cannot be uniformly covered with the antistatic layer, the surface electric resistance exceeds the allowable value (less than 1E + 9), and the antistatic effect can be sufficiently obtained. Did not. On the other hand, in Comparative Examples 4 and 5, in which the average film thickness of the antistatic layer was more than 3.5 μm, the distance from the magnetic attraction layer surface to the actual attraction surface was long, and the magnetic attraction force was reduced.

On the other hand, in Examples 1 to 4 in which the average thickness of the antistatic layer was kept at 0.5 to 3.5 μm,
The surface electric resistance and the magnetic attraction force were within the allowable range, and there was no powder dropping. From the above, it was confirmed that the average thickness of the antistatic layer was preferably in the range of 0.5 to 3.5 μm.

Example 5 As shown in Table 4 below, magnetic adsorption was carried out in the same manner as in Example 1 except that a pigment for preventing inter-paper friction was added to the antistatic paint (see Table 1) in Example 1. A sheet was prepared. As the pigment, nylon particles having an average particle diameter of 6 μm (E
(POSSTAR: manufactured by Nippon Shokubai Co., Ltd.) and 10 parts by weight of a pigment were added to 100 parts by weight of the binder resin shown in Table 1 to obtain a new antistatic paint. When this new antistatic paint was applied on the magnetically adsorbing layer, it was applied by gravure so that the average thickness of the charged applied layer obtained after drying was 1-2 μm.

Examples 6 and 7 and Comparative Examples 6 and 7 A magnetically attractable sheet was prepared in the same manner as in Example 5 except that an antistatic paint was prepared in which the average particle diameter of the carbon particles 93 was as shown in Table 4 below. Produced.

[0068]

[Table 4]

(Evaluation Results) Examples 5 and 6 described above
Table 4 shows the results of the above-described evaluation tests performed on the magnetic attraction sheets manufactured in Comparative Example 7 and Comparative Examples 6 and 7.

As is apparent from Table 4, in Comparative Example 6 in which the average particle size of the carbon particles added to the antistatic layer was less than 0.3 μm, the carbon particles were not properly dispersed in the binder resin. , Powder drop occurs during printing. On the other hand, in Comparative Example 7 in which the average particle diameter of the carbon particles exceeds 2.0 μm, the carbon particles cannot be completely retained and fall off due to friction between the paper feeding mechanism of the printer and the sheet surface during printing. In addition, since the particle size is large, the specific surface area of carbon is small, and no antistatic effect can be obtained.

On the other hand, in Examples 5 to 7 in which the average particle size of the carbon particles was 0.3 to 2.0 μm, no powder dropping occurred. From the above, it was confirmed that the average particle diameter of the carbon particles to be added to the antistatic layer is preferably 0.3 μm to 2 μm.

Examples 8 and 9 and Comparative Examples 8 and 9 A magnetically attractable sheet was prepared in the same manner as in Example 5, except that the amount of the binder resin added was as shown in Table 5 below to prepare the antistatic paint. did.

[0073]

[Table 5]

(Evaluation Results) The results of the above-described evaluation tests performed on the magnetic attraction sheets produced in Examples 8 and 9 and Comparative Examples 8 and 9 are also shown in Table 5 above.

As apparent from Table 5, in Comparative Example 8 in which the binder resin component in the antistatic layer exceeds 100 parts by weight,
Adhesion resistance cannot be obtained, and when used as a magnetic adsorption sheet for a long period of time, or when adsorbed on a hot display such as a pot, it adheres to the display. On the other hand, in Comparative Example 9 in which the amount of the binder resin component in the antistatic layer was 85 parts by weight or less, the carbon pigment could not be held by the binder resin, and powder was dropped during printing.

On the other hand, Examples 8 and 9 in which the binder resin component in the antistatic layer was maintained at 85 to 100 parts by weight.
No sticking and powdering occur. From the above, it was confirmed that 85 to 100 parts by weight of the binder resin in the antistatic layer is preferably based on 100 parts by weight of the carbon particles.

Examples 10 to 13 and Comparative Examples 10 to 12 Magnetic adsorption sheets were prepared in the same manner as in Example 5 except that antistatic paints were prepared by setting the average particle size or the amount of the pigments as shown in Table 6 below. Was prepared.

[0078]

[Table 6]

(Evaluation Results) The results of the above-described evaluation tests performed on the magnetically attracted sheets produced in Examples 10 to 13 and Comparative Examples 10 to 12 are also shown in Table 6 above.

As is clear from Table 6, in Comparative Example 10 in which the average particle size of the pigment was more than 20 μm, the pigment could not be sufficiently retained by the binder resin, and powder was dropped during printing. In addition, dispersibility in the binder resin deteriorates, and it becomes difficult to form a coating film. Even if it can be formed, the coating film becomes brittle, and the adhesive strength to the magnetic layer surface decreases.

Further, in Comparative Examples 11 and 12 in which the amount of the pigment added exceeds 20 parts by weight, the pigment cannot be sufficiently dispersed in the binder resin, and it is difficult to form a coating film. Even if it can be formed, the coating film becomes brittle, the adhesive strength is reduced, and powder is dropped during printing.

On the other hand, in Examples 10 to 13 in which a pigment having an average particle size of 4 to 20 μm was added in an amount of 5 to 20 parts by weight based on 100 parts by weight of the binder resin, no powder was removed and the adhesive strength was maintained. I'm dripping. Further, the coefficient of friction between sheets is also an allowable value (0.
25 or less). From the above, it was confirmed that the average particle size of the pigment to be added is preferably 4 to 20 μm, and the additive is preferably 5 to 20 parts by weight based on 100 parts by weight of the binder resin.

Examples 14 and 15 and Comparative Examples 13 to 15 The same as Example 5 except that the amount of cellulose acetate butyrate (CAB) or silicone oil added was as shown in Table 7 below to prepare an antistatic paint. Thus, a magnetic attraction sheet was produced.

[0084]

[Table 7]

(Evaluation Results) The results of the above-described evaluation tests performed on the magnetic attraction sheets produced in Examples 14 and 15 and Comparative Examples 13 to 15 are also shown in Table 7 above.

As is clear from Table 7, in Comparative Example 13 in which the addition amount of CAB was less than the predetermined value of 50 parts by weight, the anti-adhesion effect was weakened, so that it could be used for a long time as a magnetically adsorbing sheet or used in a pot or the like. It sticks when it is adsorbed on a noticeable body that is hot. In addition, in Comparative Example 13, since the amount of the resin including the binder resin and the CAB was small, the retention of the pigment was poor and powder dropping occurred. On the other hand, in Comparative Example 14 in which the amount of CAB added exceeded the predetermined value of 75 parts by weight, the proportion of carbon particles in the antistatic film was low, so that the antistatic effect of the antistatic film was reduced, and the surface electric resistance was unacceptable. The value is 1E + 9 (Ω) or more.

In Comparative Example 15 in which the addition amount of the silicone oil exceeds 1 part by weight, the silicone oil excessively precipitates on the surface, which causes sticking.

On the other hand, the CAB additive is maintained at 50 to 75 parts by weight per 100 parts by weight of carbon, and the silicone oil is added at 0.5 to 1 part by weight per 100 parts by weight of carbon. In Examples 14 and 15 which were kept, the anti-adhesive property and the anti-dusting property were good, and the surface electric resistance was within an allowable range. From the above, the additive of the cellulose acetate resin is 50 parts by weight based on 100 parts by weight of carbon.
It was confirmed that the amount of the silicone oil additive was preferably 0.5 to 1 part by weight based on 100 parts by weight of carbon.

Comparative Example 16 A magnetic paint containing carbon particles was applied to the recording medium a in Example 1 as shown in Table 8 below to form a magnetically attracting layer, and a magnetically attracting layer was provided without providing an antistatic layer. A sheet was prepared.

[0090]

[Table 8]

(Evaluation Results) The above-described evaluation test was performed on the magnetically attractable sheet produced in Comparative Example 16, and the results are shown in Table 7 above.

As is clear from Table 7, Comparative Example 16
However, it was not possible to satisfy the adhesion resistance and the powder falling resistance, and it was not possible to keep the surface electric resistance and the coefficient of friction between papers at acceptable values.

In Examples 1 to 15, it was confirmed that the adhesive strength could be secured.

[0094]

As described above, according to the magnetic attraction sheet of the present invention, since the antistatic layer containing carbon particles is provided on the surface of the magnetic attraction layer, generation of static electricity due to charging of the attraction surface is prevented. Thus, the electrostatic adhesion between the sheets can be suppressed, and it is possible to secure the running property during printing when printing a large amount of this magnetically attracting sheet using a printing device. As a result, double feeding during printing can be prevented, and the problem that the magnetically attracted sheet processed at the time of processing with scissors or the like sticks to clothes or a human body can be solved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a magnetic attraction sheet of the present invention.

FIG. 2 is a sectional view of a main part of an antistatic layer in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic adsorption sheet, 3 ... Nonmagnetic support, 7 ... Magnetic adsorption layer, 9 ... Antistatic layer, 91 ... Binder resin, 93 ... Carbon particles, 95 ... Pigment

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C09K 3/16 101 C09K 3/16 101B // G09F 7/04 G09F 7/04 D (C08L 101/00 (C08L 101 / 00 1:12 1:12 83:04) 83:04) F term (reference) 4F100 AA00D AA33C AA37D AH02C AH02D AH06D AJ06D AK01B AK01D AK41C AK51C AK51D AL05C AR00C AS00A AT00B BA04 BA07 BA10A J10G DEJD GBD JG10B JK16D JL00 JL00A JL05 YY00D 4J002 AB021 AB022 AC031 BC031 BD041 BD101 BE021 BF021 BG041 BG051 BG101 CD001 CF001 CG001 CK021 CP033 DA016 DA036 DE137 DE147 DJ017 FD097 FD106 GS00

Claims (11)

[Claims] 1. A magnetically attracting sheet having a magnetically attracting layer provided on a nonmagnetic support, wherein an antistatic layer comprising carbon particles dispersed in a binder resin is provided on the surface of the magnetically attracting layer. A magnetic attraction sheet characterized by the above. 2. The magnetic attraction sheet according to claim 1, wherein a surface electric resistance on the surface of the antistatic layer is 10 ⁹ Ω.
Magnetic attraction sheet characterized by being less than. 3. The magnetic attraction sheet according to claim 1, wherein the antistatic layer has an average thickness of 0.5 to 3.5 μm. 4. The magnetic attraction sheet according to claim 3, wherein the carbon particles have an average particle diameter of 0.3 to 2.0 μm.
m, a magnetically attractable sheet. 5. The magnetic attraction sheet according to claim 1, wherein the antistatic layer contains the binder resin in a ratio of 85 to 100 parts by weight based on 100 parts by weight of the carbon particles. Characteristic magnetic attraction sheet. 6. The magnetic attraction sheet according to claim 1, wherein a pigment having an average particle size of 4 to 20 μm is dispersed in the antistatic layer. 7. The magnetically attracting sheet according to claim 6, wherein a coefficient of friction between paper between the surface on the antistatic layer side and the surface on the opposite side is 0.25 or less. . 8. The magnetic attraction sheet according to claim 6, wherein the pigment is contained in the antistatic layer in an amount of 5 to 20 parts by weight based on 100 parts by weight of the binder resin. Magnetic attraction sheet. 9. The magnetically attracting sheet according to claim 8, wherein a coefficient of friction between paper between the surface on the antistatic layer side and the surface on the opposite side is 0.25 or less. . 10. The magnetically attracting sheet according to claim 1, wherein 50 to 75 parts by weight of a cellulose acetate resin is added to the antistatic layer separately from the binder resin based on 100 parts by weight of the carbon particles. A magnetic attraction sheet characterized by being made. 11. The magnetically attractable sheet according to claim 1, wherein 0.5 to 1 part by weight of silicone oil is added to 100 parts by weight of the carbon particles in the antistatic layer. Magnetic adsorption sheet.