Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2002-01-18
2004-11-16
Hardee, John R. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
Reexamination Certificate
active
06818606
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a laundry detergent sheet.
BACKGROUND ART
A laundry detergent sheet provided with a layer containing a cleansing composition and a bleaching agent and on both sides of said layer with a water-soluble substrate is known (JP-A 10-72599, JP-A 10-72593 or WO98/32835). However, since the detergent is in sheet, its surface area is smaller than the area of a powdered detergent, and since its ingredients are compressed, the laundry detergent sheet is still poor in solubility at low temperatures.
DISCLOSURE OF INVENTION
Accordingly, the object of the present invention is to provide a laundry detergent sheet with significant improvements in solubility.
The present invention relates to a laundry detergent sheet comprising a layer containing a detergent composition and, on both sides of the layer, a water-soluble substrate joined, wherein said layer comprises a water-soluble or disintegrating-in-water particle group having an average particle diameter of 60 to 2000 &mgr;m, consisting of a particle group obtained by spray-drying slurry containing at least one member selected from a water-soluble inorganic material, a water-insoluble or water-sparingly-soluble inorganic material and a water-soluble organic material, and/or a detergent particle group comprising a surfactant carried on said particle group.
MODES FOR CARRYING OUT THE INVENTION
[Water-soluble and/or Disintegrating-In-Water Particle Group]
The layer containing a detergent composition, which constitutes the laundry detergent sheet of the present invention, comprises a water-soluble or disintegrating-in-water particle group having an average particle diameter of 60 to 2000 &mgr;m, consisting of a particle group obtained by spray-drying slurry containing at least one member selected from a water-soluble inorganic material, a water-insoluble or water-sparingly-soluble inorganic material and a water-soluble organic material, and/or a detergent particle group comprising a surfactant carried on said particle group. The phrase “water-soluble or disintegrating-in-water” refers to such properties that when 0.5 g of said particle group is introduced into 1-L water at 10° C. in a 1-L beaker (in the form of a cylinder having an inner diameter of 105 mm and a height of 150 mm, for example a 1-L beaker produced by Iwaki Glass Co., Ltd.), stirred for 10 minutes at a revolution rate of 800 rpm with a stirrer (35 mm length and 8 mm diameter), and then sifted through a metal screen of 200 mesh size, the residue on the screen is less than 0.025 g. The “water-soluble or disintegrating-in-water” is preferably such that under said conditions, the time for the residue to be reduced to less than 0.025 g is within 7 minutes, particularly within 5 minutes.
The average particle diameter of said water-soluble or disintegrating-in-water particle group, as determined with the standard screen in JIS Z 8801, is 60 to 2000 &mgr;m, preferably 88 to 1410 &mgr;m, more preferably 125 to 1000 &mgr;m. It is preferable that the particle group having particle diameters less than the lower limit of the average particle diameter is less than 5% by weight of the whole particle group, while the particle group having particle diameters greater than the upper limit is less than 5% by weight of the whole particle group. If the average particle diameter is less than 60 &mgr;m, the effect of improving solubility is insufficient, while if the average particle diameter is greater than 2000 &mgr;m, the particles after washing easily remain in clothes and a washing machine.
The water-soluble or disintegrated particle group in the present invention is preferably the one having the following characteristics<1> and <2>.
<1> In the process of dissolution in water, bubbles having an at least one-tenth diameter relative to the diameter of the particles are released from the inside of the particles (particles releasing bubbles are referred to hereinafter as “bubble-releasing particles”).
The bubble-releasing particles refer to those particles which upon penetration of a small amount of water into the inside of the particles, release bubbles having a predetermined size from the inside of the particles, and then upon penetration of a large amount of water into the inside of the particles, disintegrate by themselves (autonomous disintegration of the particles) in the process of dissolution in water, whereby the dissolution of the particles starts not only from the vicinity of the surface but also from the inside of the particles. The behavior of this dissolution can be confirmed under a digital microscope, an optical microscope etc. as the phenomenon where upon dissolution in water, the bubble-releasing detergent particles release bubbles whose diameter is at least {fraction (1/10)}, preferably at least ⅕, more preferably at least ¼ and most preferably at least ⅓ (referred to hereinafter as bubbles of the predetermined size) relative to the diameter of the particles. Upon dissolution in water in a stationary state, the bubble-releasing detergent particles generate bubbles of the predetermined size preferably within 120 seconds, more preferably within 60 seconds and most preferably within 45 minutes.
The method of measuring the diameter of bubbles is as follows: A double-coated tape is attached to the center of the bottom of a Petri dish (inner diameter: 50 mm). The water-soluble or disintegrating-in-water particle group is attached to the double-coated tape. First, the diameter (&agr;&mgr;m) of individual particles in circular form is determined from its picture obtained using a digital microscope. As the digital microscope, VH-6300 produced by Keyence Co. Ltd. can be used. Then, 5 mL deionized water at 20° C. is poured into the Petri dish, and the dissolution behavior of the individual particles to be measured is observed. If bubbles are released from the inside of the particles, the diameter (&bgr;&mgr;m) of bubbles in circular form is determined from a picture of the bubbles just released from the particles. If plural bubbles are released from the inside of the particles, the maximum diameter (&bgr;&mgr;m) of the individual bubbles in circular form is determined. Then, the ratio (&bgr;/&agr;) of bubble diameter to particle diameter is determined for the individual particles. It is preferable that in the inside of the bubble-releasing detergent particles, there are pores having a diameter of {fraction (1/10)} to ⅘, preferably ⅕ to ⅘, relative to the particle diameter.
<2> When the particles are introduced into water at 5° C., stirred for 60 seconds under the following conditions and sifted through the standard screen (opening of 74 &mgr;m) prescribed in JIS Z 8801, the degree of dissolution of the particle group, as calculated by equation (1), is at least 90%.
Stirring conditions: 1 g of the particle group is introduced into 1 L hard water (71.2 mg CaCO
3
/L; molar ratio of Ca/Mg=7/3) and stirred at a revolution rate of 800 rpm with a stirrer (length, 35 mm; diameter, 8 mm) in a 1-L beaker (inner diameter, 105 mm).
Degree of dissolution (%)=[1−(
T/S
)]×100 (1)
S: Weight (g) of the particle group introduced.
T: Dry weight (g) of the residue (from the particle group) remaining on the screen through which the aqueous solution obtained under the stirring conditions described above has been sifted.
The degree of dissolution is preferably at least 94%, more preferably at least 97%.
Hereinafter, the stirring conditions are described. A 1-L beaker (in the form of a cylinder having an inner diameter of 105 mm and a height of 150 mm, for example a 1-L beaker produced by Iwaki Glass Co., Ltd.) is filled with 1 L hard water cooled at 5° C. containing 71.2 mg CaCO
3
/L (molar ratio of Ca/Mg=7/3), and the water is kept at a temperature of 5° C. in a water bath and stirred with a stirrer (35-mm length, 8 mm diameter, for example Teflon SA (round and thin stirrer) produced by Advantec Co., Ltd.) at such a revolution rate (800 rp
Hanada Hirohiko
Hayashi Hiromitsu
Ide Kazutoshi
Saijo Hiroyuki
Yamaguchi Nobuyoshi
Birch & Stewart Kolasch & Birch, LLP
Hardee John R.
Kao Corporation
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