JPH0747701B2 - Antistatic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antistatic material having an appropriate electric resistance value, and can be used, for example, as a paint for OA equipment and synthetic leather.

[Background Art] OA equipment such as computers is widely used in the present offices, and when electrostatic damage occurs in such OA equipment, there is a possibility that magnetic recordings may be lost. So OA
As paints for equipment, antistatic (10 ¹² Ω or less) or conductive (10 ⁵ Ω or less) paints with lower resistance than general paints (resistance value is around 10 ¹⁴ Ω) are used. Conventionally, such antistatic paint is used for 100 parts by weight of general paint,
It is manufactured by adding 40 to 80 parts by weight of spherical conductive filler. Further, the conductive paint is manufactured by adding 100 parts by weight or more of a conductive filler to 100 parts by weight of the paint.

On the other hand, in recent years, synthetic leather has come into practical use, and some of such synthetic leathers have antistatic properties. This synthetic leather having antistatic properties is manufactured, for example, by adding an antistatic agent to synthetic leather or using a conductive base cloth.

[Problems to be Solved by the Invention] In the case of an antistatic (including conductive) coating produced by adding only the above-mentioned conductive filler, in order to improve the contact state between spherical conductive fillers. It is necessary to increase the amount of conductive filler added. Therefore, since the conductive filler is made of an expensive material such as silver, the paint itself is expensive. In addition, such an antistatic paint has no moisture absorption and desorption property, and also has a hard touch, so that the touch is not good.

In the above-mentioned synthetic leather to which the antistatic agent is added, the antistatic agent may ooze out, in which case the antistatic performance is deteriorated and stickiness occurs.

Further, in the synthetic leather using the conductive base cloth, the static electricity generated in the skin layer is obstructed by the intermediate porous layer, so that a sufficient antistatic effect cannot be obtained.

An object of the present invention is to provide an antistatic material having excellent antistatic property and having a good feel.

[Means for Solving the Problems] The antistatic material according to the present invention is an antistatic material containing a resin base material, a moisture absorbing / releasing filler, and a conductive filler, and the resin base material With respect to 100 parts by weight, the moisture absorptive and desorptive filler is 5 to 35 parts by weight, the conductive filler is 5 to 35 parts by weight, and the sum of the moisture absorptive and desorptive filler and the conductive filler is 50 parts by weight or less. It is characterized by

Here, the antistatic property of the antistatic material means that the resistance value is 10 ¹² Ω or less, preferably 10 ⁸ Ω or less, and therefore includes a range in which the resistance is 10 ⁵ Ω or less.

As the resin base material, urethane resin and other resins can be arbitrarily used, and it is preferable that the resin base material has moisture permeability after forming a film or a layer. This is for facilitating the movement of moisture in the film or layer and for enhancing the moisture absorbing / releasing effect of the added moisture absorbing / releasing filler.

This resin base material has a composition according to the specific application of the antistatic material. For example, when using an antistatic material as a paint, it is a resin paint base material such as urethane resin paint,
This resin paint base material contains substances necessary for paint such as pigments. Further, it has the same composition when used as a leather paint. Further, in the synthetic leather, for example, a moisture absorbing / releasing filler and a conductive filler are contained in each urethane resin of a dry urethane layer formed on a base cloth or a dry urethane layer formed via a wet urethane layer. In artificial leather, for example, a wet urethane resin impregnated in a nonwoven fabric layer contains a moisture absorbing / releasing filler and a conductive filler, and a dry urethane layer urethane resin formed on this nonwoven fabric layer has a moisture absorbing / releasing filler and conductive filler. Contains a filler.

The moisture absorptive and desorptive filler is one or two or more arbitrarily selected from leather powder, silk powder, chitin powder, gelatin powder, casein powder, cellulose powder, and bamboo powder, and these It is preferable to use one having an average particle size of 30 μm or less.

If the average particle size of the moisture absorptive and desorptive filler exceeds 30 μm, the surface of the film or the like becomes uneven and is easily roughened, and further, the spray gun is clogged and uniform coating cannot be performed.
More preferably, an average particle size of 10 μm or less is used.

When the blending amount of the moisture absorbing / releasing filler is less than the above-mentioned 5 parts by weight, the desired feel cannot be obtained, and the effect of reducing the amount of the conductive filler used is reduced. Also,
When the amount exceeds 35 parts by weight, good antistatic property is exhibited, but the addition of the conductive filler tends to make the film and the like brittle. Preferably, the blending amount of the moisture absorbing / releasing filler is in the range of 8 to 25 parts by weight.

It is preferable to use conductive titanium oxide as the conductive filler. The conductive titanium oxide may have a needle shape or a shape, but a needle shape is preferable. In the case of needles, the average short diameter is 0.05 to 0.5 μm and the average long diameter is 3 to 20 μm.
Is preferred. If the average minor axis and the average major axis exceed the upper limits, the minor axis portion becomes thick, which is not preferable. On the other hand, if the major axis becomes too long, the surface of the film or the like becomes uneven, and the surface becomes rough, giving a feeling like sandpaper. In addition, the spray gun is clogged and uniform coating cannot be performed. When the minor axis portion is thin, there is no problem, but when the major axis is short, the continuity due to contact between the conductive titanium oxides in the resin base material is deteriorated, which is not preferable.

In addition to the conductive titanium oxide, for example, powder of various metals (copper, silver, aluminum, etc.) and fibrous substances (acrylic fiber, etc.) are surface-treated (plating, etc.) with tin oxide, nickel, copper, silver, etc. Those that have been subjected to, carbon (Ketjen black, furnace black, etc.) tin oxide, nickel,
It is possible to use those that have been surface-treated (plated) with copper, silver or the like. These conductive fillers are needle-shaped or plate-shaped. Preferably needle-like, the average minor axis is 0.02-1.
The average major axis is preferably 0 μm and 0.1 to 20 μm.

If the content of the conductive filler is less than 5 parts by weight, the conductivity becomes insufficient. On the other hand, when the amount exceeds 35 parts by weight, the effect of adding the moisture absorptive and desorptive filler decreases. Preferably, the conductive filler content is 8 to 25
The range is parts by weight.

In the present invention, the amount of each of the moisture absorptive and desorptive filler and the conductive filler is regulated within the above range, and the sum of the moisture absorptive and desorptive filler and the conductive filler is 50 parts by weight or less. When this sum exceeds 50 parts by weight, the surface condition becomes rough or rough, and the film becomes brittle and the strength is lowered.

The antistatic material according to the present invention is obtained by adding a moisture absorptive and desorptive filler and a conductive filler to a resin base material, mechanically mixing them, and uniformly dispersing them. Any mixing method can be used as long as it can be mixed without allowing the antistatic material to absorb moisture.

Specific applications of the antistatic material according to the present invention are arbitrary such as paints for OA equipment, synthetic leather, artificial leather, which require antistatic properties.

[Operation] When it is attempted to form the antistatic material only with the resin base material and the conductive filler, the antistatic property cannot be obtained unless the conductive filler is added in a minimum required amount or more. It is possible to slightly reduce the minimum required amount of the conductive filler by adding a little amount of the moisture absorbing and releasing filler at the time of adding the minimum required amount of the conductive filler where the electric resistance starts to decrease, but the effect is not obtained by adding the moisture absorbing and releasing filler. Few. However, in the range where the amount of the conductive filler added becomes the minimum required amount or more and the electrical resistance decreases linearly with the increase of the amount of the conductive filler added, the effect of adding the moisture absorbing / releasing filler is the most effective. Appear effectively. In addition, in the saturated region where the electrical resistance does not further decrease even if the conductive filler is added, the effect of adding the moisture absorbing / releasing filler cannot be obtained. Therefore, in the addition amount of 5 to 35 parts by weight, which is the range in which the electric resistance is linearly reduced by the addition of the conductive filler, 10 to 10 ⁴ by adding the moisture absorbing and releasing filler in the range of 5 to 35 parts by weight. A reduction in electrical resistance of about Ω will be obtained.

As a result, compared with the conventional antistatic material, while reducing the amount of addition of expensive and non-moisture-absorbing conductive filler, by adding inexpensive and hygroscopic filler, good antistatic property At the same time, an inexpensive antistatic material having a good feel can be obtained.

[Examples] Example 1 A two-component urethane paint was used as a resin base material, and 100 parts by weight of this two-component urethane paint, 24 parts by weight of leather powder as a moisture absorbing / releasing filler and needle-like oxidation as a conductive filler were used. Titanium was added to 8 parts by weight and mechanically mixed, and these were uniformly dispersed to obtain an antistatic coating as an antistatic material according to this example.

The two-component urethane paint used in this example was Senosoft [trade name, manufactured by Cashew Co., Ltd.], and 80 parts by weight of the main component Senosoft-A liquid and 16 parts by weight of the curing agent Senosoft-B liquid were used. And 4 parts by weight of a curing accelerator.

The leather powder used has an average particle size of 5 μm.

The needle-shaped conductive titanium oxide used is FT2000 [trade name, manufactured by Ishihara Sangyo Co., Ltd.].

Next, this antistatic paint was diluted with a diluent solvent, Cashew Stron # 2240 thinner (trade name, manufactured by Cashew Co., Ltd.), and the paint was diluted with a spray gun [Iwata Wyder 71 (trade name), Iwata Coating Machine Industry Co., Ltd. Co., Ltd.] was applied to an ABS plate so that the thickness of the coating film when dried was 50 μm. After coating, it was dried at 60 ° C. for 40 minutes.

Next, with respect to the formed coating film of the antistatic paint, the feel of the surface was evaluated as described below, and the surface specific resistance and the moisture absorption / release property were measured. The results are shown in Table-1. In addition, both evaluation and measurement were performed in a room at 23 ° C. and 50% RH (relative humidity).

Evaluation method of surface feel In accordance with the distribution method, which is one of the sensory tests, 10 inspectors touch the surface of the coating film, and dry touch is evaluated as ○ and non-dry touch is evaluated as ×. As a result, if the evaluations of 8 or more inspectors are in agreement, it is designated as ○ or ×, and 7 to
The case where the five inspectors agree on the evaluation is Δ.

Measuring method of surface resistivity The surface resistivity is measured using a measuring device [manufactured by Hewlett Packard Co., measuring cell: 16008A, measuring unit: 4329A].

Method for measuring moisture absorption and desorption characteristics This method for measuring moisture absorption and desorption characteristics is based on the light output method, moisture absorption from the surface of a film-like or sheet-like synthetic leather having hygroscopicity and hygroscopicity and front and back surfaces, The method for measuring the moisture release rate is specified.

First, as shown in FIG. 1, a square sample 11 with a side of 130 mm cut out (or punched out) from an original sample that had been conditioned for 24 hours at 23 ° C. and 50% RH for 24 hours was used for moisture absorption measurement and release. Prepare one each for humidity measurement. And the sample 11 for moisture absorption measurement is at 23 ° C, 30%
Leave it in the RH constant temperature and humidity chamber for 24 hours to adjust the condition.
On the other hand, the humidity release sample 11 is left in a constant temperature and humidity chamber at 23 ° C. and 80% RH (or a container containing a saturated solution of ammonium sulfate in the same atmosphere) for 24 hours for conditioning.

Next, prepare two square aluminum plates 12 each having a side of 130 mm, attach a double-sided adhesive tape 13 having a width of 15 mm to the periphery of each aluminum plate 12, and then overlap the aluminum plates 12 so that the double-sided adhesive tape 13 Sample for moisture release measurement 11
Paste. Then, the periphery is sealed with a vinyl tape 14 having a width of 15 mm.

Next, the moisture absorption measurement sample 11 is left for a predetermined time in a constant temperature and humidity chamber at 23 ° C. and 80% RH (or a container containing a saturated ammonium sulfate solution in an equivalent atmosphere). On the other hand, the humidity release measurement sample 11 is left for a predetermined time in a constant temperature and humidity chamber at 23 ° C. and 30% RH.

Next, each sample 11 is taken out from the constant temperature and humidity chamber at each measurement time, and the weight (including the aluminum plate 12 etc.) immediately after 1 minute is measured up to 1 mg by a balance and recorded. This balance has a measurable weight of 300 g or more with a 1 mg sensitivity. Immediately thereafter, the sample 11 is returned to the original constant temperature and humidity chamber. 20 minutes, 40 minutes, 60 minutes from the start of measurement
After each of minutes, 90 minutes, 120 minutes and 180 minutes.

Next, from these measurement results, the moisture absorption / desorption rate Vg / m ² per 1 m ^{2 at} each measurement time is obtained as follows.

V = [(W ₁ −W ₀ ) / 10 ³ ] × [10 ⁴ / S] where W ₁ is the weight of the sample 11 (including the aluminum plate 12 etc.) at each measurement time, and W ₀ is the sample 11 Dry or wet basis weight, S is the exposed surface area of sample 11 (about 100c
m ² ). In this measurement, it is assumed that the portion held by the vinyl tape 14 does not absorb or release moisture.

In Hygroscopic properties tables, ○ is moisture-absorbing and desorbing rates of 60 minutes after the start of measurement is 1 g / m ² or more, △ is 1~0.5g / m ^2, × indicates a 0.5 g / m ² or less.

Examples 2 to 5 Similarly to the above Example 1, also in Examples 2 to 5, after forming a coating film using the antistatic paint according to each Example, the feel of the surface was evaluated, and the surface was also evaluated. The specific resistance and moisture absorption / release characteristics were measured. The results are shown in Table-1.

However, the proportion of the leather powder mixed in the two-component urethane paint and the proportion of the needle-shaped conductive titanium oxide or spherical conductive titanium oxide used as the conductive filler were varied as shown in Table 1. The spherical titanium oxide used was ET500W.
[Product name, manufactured by Ishihara Sangyo Co., Ltd.].

Comparative Examples 1 to 6 After forming coating films using the coating materials according to each Comparative Example, the surface feel was evaluated, and the surface specific resistance and moisture absorption / desorption characteristics were measured as in the above Examples. The results are shown in Table-1.

However, in Comparative Example 1, a paint containing only a two-component urethane paint, in Comparative Example 2 a paint containing only leather powder added to a two-component urethane paint, and in Comparative Examples 3 to 5, only conductive titanium oxide was added to a two-component urethane paint. Paint, in Comparative Example 6, a two-component urethane paint containing leather powder and conductive titanium oxide was used. Table 1 also shows the mixing ratio of the leather powder and the type and mixing ratio of the conductive titanium oxide in the paint used in the comparative example.

From Table-1, the coating films according to Examples 1 to 5 were coated with 8 to 24 parts by weight of leather powder and 8 to 24 parts by weight of conductive titanium oxide per 100 parts by weight of the two-component urethane paint. It can be seen that all the coating films have good surface feel and good moisture absorption and desorption characteristics because they were formed using an electro-conductive paint. Also,
The surface resistivity of each coating film was 5 × 10 ⁹ Ω or less, and favorable antistatic property was obtained.

On the other hand, since the coating film according to Comparative Example 1 was formed by using a paint containing neither leather powder nor titanium oxide, the surface feel and the moisture absorption / desorption property are poor. I understand. Further, the coating film had a surface specific resistance of 5 × 10 ¹⁴ Ω and could not obtain antistatic property.

Further, since the coating film according to Comparative Example 2 was formed by using the coating material to which only the leather powder was added, the surface feel and the moisture absorbing / releasing property are good, but the surface specific resistance of the coating film. Is 2 ×
It was 10 ¹² Ω, and favorable antistatic property was not obtained.

Since the coating films according to Comparative Examples 3 to 5 are formed by using the coating material to which only conductive titanium oxide is added, there is a problem in at least one of the feel of the surface, the moisture absorption / release characteristics, and the surface resistivity. You can see that there is.

The coating film according to Comparative Example 6 was formed using a coating material containing both leather powder and conductive titanium oxide, but the mixing ratio of the leather powder was 40 parts by weight and the upper limit according to the present invention (35 Parts by weight)
Therefore, even though there is no problem in the feel of the surface, moisture absorption / release characteristics and surface resistivity, the viscosity of the coating is too high, and the coating film becomes very brittle, which is a problem in practical use.

[Effects of the Invention] According to the present invention, an antistatic material having excellent antistatic property and good touch can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing how to prepare a sample used in the method for measuring the moisture absorption / desorption characteristics. 11 …… Sample, 12 …… Aluminum plate.

Claims (3)

[Claims] 1. An antistatic material containing a resin base material, a moisture absorptive and desorptive filler, and a conductive filler, wherein 5 parts of the moisture absorptive and desorptive filler is added to 100 parts by weight of the resin base material. ~ 35 parts by weight, the conductive filler 5 ~ 35 parts by weight, and the sum of the moisture absorbing and releasing filler and the conductive filler
An antistatic material characterized by being 50 parts by weight or less. 2. The moisture absorptive and desorptive filler has an average particle diameter of 30 μm.
The antistatic material according to claim 1, which is arbitrarily selected from the following leather powder, silk powder, chitin powder, gelatin powder, casein powder, cellulose powder, and bamboo powder. 3. The antistatic material according to claim 1 or 2, wherein the conductive filler is conductive titanium oxide.