DESCRIPTION

DURATION INDICATOR

TECHNICAL FIELD

The present invention relates to a duration indicator, an insect pest-controlling device comprising a duration indicator, and a method for checking an effective period of an insect pest-controlling device comprising a duration indicator.

BACKGROUND ART

An indicator is known, which causes a predetermined indication to appear or disappear on a display in accordance with the remaining amount of a contained liquid (see, for example, Japanese Examined Utility Model Publication No. 5-938/1993) .

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an excellent duration indicator.

According to the first aspect, the present invention provides a duration indicator comprising a liquid substance-retaining sheet and an olefin resin film with a

thickness of 10 to 100 μm coated on the whole of said liquid substance-retaining sheet, wherein said liquid substance-retaining sheet comprises a sheet substrate retaining a liquid substance and having a base layer and at least one indicator layer which is laminated on at least a part of at least one surface of the base layer and which shows at least two visually different states depending on a change in an amount of the liquid substance retained in the indicator layer. According to the second aspect, the present invention provides an insect pest-controlling device with an expiration-indicating function, comprising the duration indicator according to the first aspect of the present invention, and an insect pest-controlling material, which are mounted on a support member.

According to the third aspect, the present invention provides a method for checking an effective period of an insect pest-controlling material based on a visual change in the state of a duration indicator according to the first aspect of the present invention after setting the duration indicator and the insect pest-controlling material at a place where insect pests live or intrude.

The duration indicators of the present invention can be readily used outdoors, while the conventional duration indicators have problems in weather resistance when used

outdoors .

Accordingly, the duration indicators of the present invention can be used to check the effective periods of various insect pest-controlling materials for use outdoors, for example, resinous insect pest-controlling materials which comprise thermoplastic resins retaining insect pest- controlling components.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a front view of an embodiment of the sheet substrate for use in the duration indicator of the present invention. The sheet substrate (3) retains a liquid substance, and has a base layer (2) and an indicator layer (1) . Fig. 2 shows a plan view of an embodiment of the duration indicator of the present invention obtained using the sheet substrate shown in Fig. 1. When the use of this duration indicator starts, the letters of "REPLACE" are not seen because the liquid substance is retained in the sheet substrate. The sheet substrate (3) is covered with olefin resin films (4), and a heat-sealed part (5) is made at the outer periphery.

Fig. 3 shows a perspective view of an embodiment of a cartridge (D) assembled by combining the duration indicator of the present invention, an insect pest-controlling

material (B) which retains an insect pest-controlling component in a net-like carrier, and a frame (C) for supporting these matters. The duration indicator (A) of the present invention is set in the center of the insect pest-controlling material (B) .

Fig. 4 shows a perspective view of an embodiment of an insect pest-controlling device with an expiration- indicating function, obtained by disposing the cartridge shown in Fig. 3 on an air-blowing means (F) having a motor (E) .

Fig. 5 shows a front view of an embodiment of an insect pest-controlling device (N) with an expiration- indicating function of the present invention, obtained by mounting, on a supporting frame (M) , the duration indicator (K) of the present invention and a resinous insect pest- controlling material (L) which comprises a net-like molded thermoplastic resin retaining an insect pest-controlling component .

Fig. 6 show a perspective view of the insect pest- controlling device with the expiration-indicating function of the present invention shown in Fig. 5, which is seen being hung on a clothes rod in a drying place.

DETAILED DESCRIPTION OF THE INVENTION A duration indicator of the present invention

comprises a liquid substance-retaining sheet and an olefin resin film with a thickness of 10 to 100 μm coated on the whole of the liquid substance-retaining sheet, and the liquid substance-retaining sheet comprises a sheet substrate retaining a liquid substance and having at least one indicator layer which is laminated on one surface or both surfaces thereof and which shows at least two visually different states depending on a change in an amount of the liquid substance retained therein. In the present invention, the sheet substrate having the base layer and the indicator layer or layers is not particularly limited, insofar as it has the above- described indicator layer (s). In a preferred embodiment of the present invention, the sheet substrate comprises a base layer and at least one indicator layer which is laminated on a part of or the whole of one surface or both surfaces of the base layer and which turns transparent when a liquid substance is contained in the indicator layer.

The base layer consists of a sheet made of a material which can retain a liquid substance, for example, a fibrous and/or porous material. Examples of the fibrous sheet include a paper sheet, a paperboard, a synthetic fiber-mixed paper sheet, a non-woven fabric, a felt-like woven fabric and fabric-like inorganic fibers. Examples of the porous sheet include porous ceramics and the like. As

such a base layer, a base layer having a weight of generally from 5 to 1,500 g/m ² , preferably from 10 to 1,000 g/m ² , is used.

Preferably, the base layer is colored in order to enhance the visibility of the change of the indicator layer. For example, the colored base layer is made of a previously colored fibrous material, or is obtained by impregnating the base layer with a coloring agent; or a coloring material is applied to or printed on the surface of the base layer.

The indicator layer which turns transparent when the liquid substance is contained in the sheet substrate is a layer which is transparent when the liquid substance is contained therein and which is opaque when the liquid substance is not contained therein. Accordingly, the indicator layer can show visually different states, that is, the indicator layer takes the color of the base layer or the color of itself depending on a change of the retained amount of the liquid substance. The layer which turns transparent when the liquid substance is contained therein is usually porous and permeable to a liquid substance.

The indicator layer which turns transparent when the liquid substance is contained therein is formed of a mixture of a binder with a material which shows a low refractive index when a liquid substance is contained, for

example, an inorganic pigment such as amorphous silica, kaolin, calcium carbonate, etc., an organic pigment such as fine particles of a plastic pigment, etc., or pulp powder. In this case, polyvinyl acetate, an ethylene-vinyl acetate copolymer, NBR, SBR, or acrylic or other latex may be used as the binder.

The indicator layer which turns transparent when the liquid substance is contained therein can be laminated on the base layer, for example, by coating, printing (e.g. screen printing, off-set printing, gravure printing or the like) or the like.

The thickness of such an indicator layer is adjusted to generally from 4 to 150 g/m ² , preferably from 10 to 60 g/m ² . When the indicator layer is laminated on the base layer by printing, the ratio of the material showing a low refractive index to the binder is such that the binder is present in an amount of about 10 to about 30 parts by weight per 100 parts by weight of the material showing a low refractive index. When the indicator layer is laminated on the base layer by coating, the ratio of the material showing a low refractive index to the binder is such that the binder is present in an amount of about 50 parts by weight per 100 parts by weight of the material showing a low refractive index.

The indicator layer which turns transparent when the liquid substance is contained therein may be laminated on the whole of the base layer, or may be laminated on a part of the base layer so that the indicator layer can be shaped in the letters of, for example, "END", "EXPIRED" or "REPLACE" .

To retain the liquid substance in the sheet substrate, for example, the sheet substrate is impregnated with the liquid substance. The amount of the liquid substance retained in the sheet substrate is generally from 0.001 to 0.7 g, preferably from 0.01 to 0.5 g, per 1 cm ³ of the apparent volume of the sheet substrate.

In the present invention, the liquid substance is not limited, and may be appropriately selected in accordance with the application. For example, the liquid substance may by an ester has a vapor pressure of 5.0 x 10 ^{" 6} to 5.0 x 10 ^~4 mmHg, preferably 5.O x 10 ^"6 to 1.0 x 10 ^"4 mmHg, at 25°C, determined by the method reported by Stephen F. Donovan ("New Method for Estimating Vapor Pressure by the Use of Gas Chromatography", Journal of Chromatography A. 749 (1996) , pp 123-129, hereinafter referred to as "Donovan method") .

Examples of the ester which has a vapor pressure of 5.0 x 10 ^"6 to 5.0 x 10 ^~4 mmHg at 25°C determined by the Donovan method include monoesters such as isopropyl

myristate (vapor pressure at 25°C: 5.5 x 10 ⁵ mmHg) , butyl laurate (vapor pressure at 25°C: 8.7 x 10 ^"5 mmHg) and isopropyl palmitate (vapor pressure at 25°C: 8.1 x 10 ^"δ mmHg); and triethyl citrate (vapor pressure at 25°C: 4.1 x 10 ^~4 mmHg) and acetyltriethyl citrate (vapor pressure at 25°C: 1.5 x 10 ^"4 mmHg) .

In the present invention, these liquid substances may be used singly, or as a mixture of two or more of them.

The duration indicator of the present invention is produced by coating the whole of the liquid substance- retaining sheet as prepared above, with an olefin resin film.

Examples of a resin for use in the olefin resin film include polyethylene (low density polyethylene (linear and branched) and high density polyethylene) and polypropylenes . Films formed of these materials may be non-oriented ones, or uniaxially or biaxially oriented ones,

A specific example of a non-oriented linear low density polyethylene film is a LIX ^® film L4102 manufactured by TOYOBO CO., LTD. Specific examples of a non-oriented polypropylene film include PYLEN ^® films CTP-I Oil and OT P- 1111 manufactured by TOYOBO CO., LTD. Specific examples of a biaxially oriented polypropylene film include PYLEN films OT P-2161 and OT P-2261 manufactured by TOYOBO CO., LTD.

The kind and thickness of the olefin resin film used in the present invention may be appropriately selected according to the indicating period of the duration indicator. The thickness of the film is generally from 10 to 100 μm, preferably from 10 to 70 μm.

The duration indicator of the present invention is produced by coating the entire periphery of the liquid substance-retaining sheet. To coat the sheet, for example, the upper and lower surfaces of the liquid substance- retaining sheet are coated with the olefin resin films, and the margins of the olefin resin films overlapped at the outer periphery of the liquid substance-retaining sheet are heat-sealed; or the liquid substance-retaining sheet is put in a bag made of the olefin resin film, and the opening of the bag is heat-sealed.

The duration indicator of the present invention is sealed in a sealing material such as a gas barrier resin film, an aluminum laminate or the like for the storage thereof. When the stored duration indicator is used, the sealing material is opened and removed to use the duration indicator.

A part of the outer surface of the olefin resin film may be coated with the above-described sealing material to such an extent that the visibility of the indicator layer is not impaired. Thereby, it is possible

to control a period of time from the start of use of the duration indicator to a visual change of the indicator layer.

For example, the duration indicator of the present invention is mounted together with an insect pest- controlling material to provide an insect pest-controlling device, so that the effective period of the insect pest- controlling material can be visually known with ease. As such an insect pest-controlling material, there are exemplified an insect pest-controlling material which comprises a thermoplastic resin retaining an insect pest- controlling component which evaporates at an ambient temperature, disclosed in US-A 2006/0052444, and an insect pest-controlling material for use in an air blower type mosquito-trapping device, disclosed in JP-A-11-92303.

In such a case, a material for the sheet substrate, the kind and the retaining amount of the liquid substance, the kind of the olefin resin film, etc. are selected so that the indicator layer can visually change at the expiration of a previously measured effective period of the insect pest-controlling material. Thereby, the duration indicator of the present invention which is suitable for the insect pest-controlling material can be provided. An insect pest-controlling device with an

expiration-indicating function is provided by mounting, on a support member, an insect pest-controlling material and the duration indicator of the present invention of which the indicator layer visually changes at the expiration of the effective period of the insect pest-controlling material. By setting this insect pest-controlling device at a place where insect pests live or intrude, insect pests can be controlled, and also, the expiration of the effective period of the insect pest-controlling material can be confirmed by the visual change of the duration indicator. Therefore, a time at which the insect pest- controlling material should be replaced can be easily determined.

When such an insect pest-controlling material is used in an air blower type mosquito-trapping device, the duration indicator and the insect pest-controlling material may be separately mounted on the support member on the upstream side or the downstream side from an air current caused by the air blowing means. For example, as shown in Figs. 3 and 4, a duration indicator A, insect pest- controlling materials B and a frame C for supporting these members are combined to assemble a cartridge D. This cartridge D is disposed on the upstream side or the downstream side from the air current from a fan type air blower F as the air blowing means to provide an insect

pest-controlling device with an expiration-indicating function. This insect pest-controlling device with the expiration-indicating function is set at a place where insect pests live or intrude, and the motor E is actuated. In the meantime, an insect pest-controlling material comprising a thermoplastic resin retaining an insect pest-controlling component which evaporates at an ambient temperature can be used in the same manner as in the above air blower type mosquito-trapping device. For example, as shown in Fig. 5, a duration indicator K and an insect pest-controlling material L are mounted on a frame M for supporting these members to assemble an insect pest- controlling device N with an expiration-indicating function. For example, this insect pest-controlling device N with the expiration-indicating function is suspended using a hook provided on the frame at a place where insect pests live or intrude, as shown in Fig. 6.

Hereinafter, the present invention will be described by making reference to Production Examples and Test Examples, which should not be construed as limiting the scope of the present invention in any way.

Production Example 1

As shown in Fig. 1, a sheet substrate was produced by partially laminating white letters indicating

"REPLACE" as an indicator layer on one surface of a blue wet non-woven fabric (2.0 cm x 2.8 cm x 0.4 mm thickness; weight: 84 g/m ² ) . The white letters were formed by screen- printing of a mixture of amorphous silica and an acrylic latex in a ratio of 1 : 0.5 in an amount of 15 g/m ² . Then, the sheet substrate was impregnated with isopropyl myristate (about 25 mg) to cause the indicator layer to turn transparent to produce a liquid substance-retaining sheet . Both surfaces of this liquid substance-retaining sheet were sandwiched between films each having a thickness of 30 μm sold under LIX ^® film L4102 (a linear low density polyethylene film having a density of 0.92 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (I)) was obtained.

Production Example 2

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 1 were sandwiched between films each having a thickness of 20 μm sold under PYLEN ^® film OT P2161 (a biaxially oriented

polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention

(hereinafter referred to as the duration indicator (2)) was obtained.

Production Example 3 Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 1 were sandwiched between films each having a thickness of

30 μm sold under PYLEN ^® film OT P2161 (a biaxially oriented polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (3)) was obtained.

Production Example 4

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 1 were sandwiched between films each having a thickness of

30 μm sold under PYLEN ^® film CT PlOIl (a non-oriented polypropylene film having a density of 0.90 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (4)) was obtained.

Production Example 5

As shown in Fig. 1, a sheet substrate was produced by partially laminating white letters indicating "REPLACE" as an indicator layer on one surface of a blue wet non-woven fabric (2.0 cm x 2.8 cm x 0.4 mm thickness; weight: 84 g/m ² ) . The white letters were formed by screen- printing of a mixture of amorphous silica and an acrylic latex in a ratio of 1 : 0.5 in an amount of 15 g/m ² . Then the sheet substrate was impregnated with isopropyl palmitate (about 25 mg) to cause the indicator layer to turn transparent to produce a liquid substance-retaining sheet.

Both surfaces of this liquid substance-retaining sheet were sandwiched between films each having a thickness of 30 μm sold under LIX ^® film L4102 (a linear low density polyethylene film having a density of 0.92 g/cm ³ ,

manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention , (hereinafter referred to as the duration indicator (5)) was obtained.

Production Example 6

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 5 were sandwiched between films each having a thickness of

20 μm sold under PYLEN ^® film OT P2161 (a biaxially oriented polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (6)) was obtained.

Production Example 7

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 5 were sandwiched between films each having a thickness of 30 μm sold under PYLEN ^® film OT P2161 (a biaxially oriented

polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention

(hereinafter referred to as the duration indicator (7) ) was obtained.

Production Example 8 Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 5 were sandwiched between films each having a thickness of

30 μm sold under PYLEN ^® film CT PlOIl (a non-oriented polypropylene film having a density of 0.90 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (8)) was obtained.

Production Example 9

As shown in Fig. 1, a sheet substrate was produced by partially laminating white letters indicating "REPLACE" as an indicator layer on one surface of a blue

wet non-woven fabric (2.0 cm x 2.8 cm x 0.4 mm thickness; weight: 84 g/m ² ) . The white letters were formed by screen- printing of a mixture of amorphous silica and an acrylic latex in a ratio of 1 : 0.5 in an amount of 15 g/m ² . Then, the sheet substrate was impregnated with butyl laurate (about 25 mg) to cause the indicator layer to turn transparent to produce a liquid substance-retaining sheet. Both surfaces of this liquid substance-retaining sheet were sandwiched between films each having a thickness of 30 μm sold under LIX ^® film L4102 (a linear low density polyethylene film having a density of 0.92 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention

(hereinafter referred to as the duration indicator (9)) was obtained.

Production Example 10 Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 9 were sandwiched between films each having a thickness of 20 μm sold under PYLEN® film OT P2161 (a biaxially oriented polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the

laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (10) ) was obtained.

Production Example 11

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 9 were sandwiched between films each having a thickness of 30 μm sold under PYLEN ^® film OT P2161 (a biaxially oriented polypropylene film having a density of 0.91 g/cm ³ , manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (11) ) was obtained.

Production Example 12

Both surfaces of a liquid substance-retaining sheet produced in the same manner as in Production Example 9 were sandwiched between films each having a thickness of

30 μm sold under PYLEN ^® film CT PlOIl (a non-oriented polypropylene film having a density of 0.90 g/cm ³ ,

manufactured by TOYOBO CO., LTD.), and the margins of the laminated films 1 mm away from the outer peripheral edge of the liquid substance-retaining sheet were heat-sealed. Thus, a duration indicator of the present invention (hereinafter referred to as the duration indicator (12)) was obtained.

Production Example 13

A duration indicator (13) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(1) on the opposite side of the indicator layer.

Production Example 14 A duration indicator (14) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(2) on the opposite side of the indicator layer.

Production Example 15

A duration indicator (15) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(3) on the opposite side of the indicator layer.

Production Example 16

A duration indicator (16) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator (4) on the opposite side of the indicator layer.

Production Example 17

A duration indicator (17) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(5) on the opposite side of the indicator layer.

Production Example 18

A duration indicator (18) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(6) on the opposite side of the indicator layer.

Production Example 19 A duration indicator (19) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(7) on the opposite side of the indicator layer.

Production Example 20

A duration indicator (20) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator (8) on the opposite side of the indicator layer.

Production Example 21

A duration indicator (21) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator (9) on the opposite side of the indicator layer.

Production Example 22

A duration indicator (22) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(10) on the opposite side of the indicator layer.

Production Example 23

A duration indicator (23) of the present invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator

(11) on the opposite side of the indicator layer.

Production Example 24 A duration indicator (24) of the present

invention was obtained by coating, with an aluminum foil, the whole of the other surface of the duration indicator (12) on the opposite side of the indicator layer. Next, Test Examples will be illustrated.

Test Example 1

The duration indicators (1), (2), (3), (5), (6), (7), (13), (14) and (15) of the present invention were left to stand still at a temperature of 30°C under a stream of an air at an air velocity of 0.5 m/sec. Then, how long time (a color changing period) was taken for each of the indicator layers of the duration indicators to distinctly turn white was measured (twice) .

The results are shown in Table 1. Table 1