EP1828362A1

EP1828362A1 - Composition of laundry detergent improving touch feel of clothes and manufacturing method thereof

Info

Publication number: EP1828362A1
Application number: EP04822503A
Authority: EP
Inventors: Young-Kee Oh; Kee-Heon Cho; Sang-Woon Kwak; Jung-Whan Oh
Original assignee: LG Household and Health Care Ltd
Current assignee: LG H&H Co Ltd
Priority date: 2004-11-30
Filing date: 2004-11-30
Publication date: 2007-09-05
Also published as: EP1828362A4; WO2006059811A1; JP2008521995A; CN101068912A

Abstract

Disclosed are a composition of laundry detergent capable of improving touch feel of clothes after laundering; and a manufacturing method thereof. The present invention provides a composition of laundry detergent including: (a) 0.1 to 15 parts by weight of an acidic form of water-soluble polymer; (b) 5 to 20 parts by weight of an anionic surfactant; (c) 10 to 70 parts by weight of an alkaline builder; and (d) 0.5 to 20 parts by weight of an organic acid coated so that it can be separated from the alkaline builder. The composition of laundry detergent according to the present invention is useful to improve soft feel of clothes by reducing possibility that calcium carbonate or a water-insoluble water softener remains in clothes after laundering, and also the composition of laundry detergent is stable because there is little caking phenomenon, and has an excellent solubility and washability in cold water. The manufacturing method of the present invention does not need an additional drying process so as to manufacture the powder detergent, as well as it is simple and economical.

Description

COMPOSITION OF LAUNDRY DETERGENT IMPROVING TOUCH FEEL OF

CLOTHES AND MANUFACTURING METHOD THEREOF

TECHNICAL FIELD

The present invention relates to a composition of laundry detergent capable of

improving touch feel of clothes after laundering, and a manufacturing method thereof.

BACKGROUND ART

Generally, a washing effect is more excellent in soft water than in hard water

including a large amount of magnesium ion and calcium ion. That is why powder

detergents generally include a water softener such as zeolite and so on. The water

softener such as zeolite and so on mainly used in the prior art has a problem that it

remains in clothes even after clothes are rinsed due to its water-insoluble property.

And it also has a problem that it has a relatively slow softening effect of the hard water

since it takes relatively much time to form the inclusion of ions, and therefore the calcium ions remaining in clothes upon their washing binds to carbonate ions ionized from the alkaline builder and so on, to form calcium carbonate, and the resultant

calcium carbonate remains in clothes (builder up). In order to solve the problems,

zeolite grinded into a fine particle size was used, but still has aforementioned problems.

U.S. Patent No. 6,770,611 discloses that α-sulfofatty acid ester surfactant and

silicate were used to reduce the problems, and U.S. Patent No. 5,977,053 discloses

iminodisuccinate was used to prevent clothes from being discolored by removing heavy

metal ions adversely affecting its washing and preventing calcium salt from sticking to clothes. However, the aforementioned problems remain to be solved.

Meanwhile, Korea Patent No. 1993-0003152 discloses a tablet type of detergent

rather than powder on the basis of its easy metering, wherein an alkaline builder and a

water-soluble multivalent carboxylic acid were used to degrade the tablet detergent

rapidly by allowing bubbles to be generated when the clothes are washed. However,

zeolite and others were used as water softeners, but the aforementioned problems were

not still solved, and there is also a problem that the stability of the detergent is

deteriorated during its storage due to the increased possibility that the acidic materials

such as carboxylic acid and others are in contact with the alkaline materials such as

alkaline builder and others when the materials are compressed into the tablet, and to the

caking phenomenon formed by neutralizing reaction with moisture in the air during its

storage.

As well as the aforementioned tablet detergent composition, the powder-type

detergent compositions including a large amount of basic materials such as alkaline

builder and others have a problem that its stability may be deteriorated during its storage,

for example caking was formed by neutralization reaction due to various causes if acidic

materials were used in the compositions, and shows a highly increased possibility that there is a contact between acidic materials and basic materials to neutralize each other

also in its manufacturing process. Meanwhile, a powder detergent is generally manufactured by preparing slurry

using an acidic form of polymer, and then drying the slurry. At this time, a low-density

powder detergent may be preferably used for washing since it has an excellent solubility

in cold water and an advantage that residuals do not remain in clothes upon their washing, compared to a high-density powder detergent. In Japanese Patent Laid-Open

Publication Nos. 61-69900 and 61-69898, a low-density powder detergent having a

density of 0.6 g/ml or less was manufactured using a counter-flow spray dryer. The

method described in the publications should necessarily undergo a drying step, and

therefore it has problems that the solubility of products may be reduced and it is difficult

to maintain quality of the powder detergent product. And it also has a disadvantage

that manufacturing cost is very high due to its complex process, and the cost of

equipment and maintenance, and repairing expense is increased when the counter-flow

spray dryer is used. In order to solve the disadvantages, European Patent Nos. A 0 390

251 and 0 544 365 Bl disclose a method for manufacturing a low-density detergent by

directly neutralizing alkyl benzene sulfonic acid in a mixer. In the aforementioned

methods, the powder detergent was manufactured by preparing salt of alkyl benzene

sulfonic acid, and then carrying out granulation of the salt using a surface modifier, but

it still has problems that it is difficult to neutralize fatty acid or alkyl benzene sulfonic

acid completely, and therefore the quality of the final product may be deteriorated due to

the presence of unreacted remnants, in addition it is difficult to manufacture a

low-density detergent having apparent density of 0.6 g/ml or less since it has very high density.

In order to solve the aforementioned problems, a steam-blast mixer was used for

manufacturing a detergent instead of the conventional counter-flow spray dryer in

Korean Patent Publication No. 2000-0046629. That is, the process for manufacturing

the detergent was conducted within shorter processing time by spraying steam and water

in the inside of the mixer to directly neutralize alkaline builder, alkyl benzene sulfonic acid and fatty acid, followed by sequentially undergoing processes such as granulation,

surface modification and translocation of the powder detergent. However, the method

has disadvantages that it necessarily needs an additional apparatus for spraying steam

and water, as well as its manufacturing cost is very high.

DISCLOSURE QF INVENTION

Accordingly, the present invention is designed to solve the problems of the prior

art, and therefore it is an object of the present invention to provide a composition of

laundry detergent capable of swiftly softening hard water and improving touch feel of

clothes by reducing remnants present in clothes after laundering, and also showing a

good stability due to little caking phenomenon during storage and an excellent

washability; and a manufacturing method thereof.

More specifically, the present invention provides a composition of laundry

detergent including: (a) 0.1 to 15 parts by weight of an acidic form of water-soluble

polymer; (b) 5 to 20 parts by weight of an anionic surfactant; (c) 10 to 70 parts by

weight of an alkaline builder; and (d) 0.5 to 20 parts by weight of an organic acid coated

so that it can be prevented from being in contact with the alkaline builder.

Also, the present invention provides a method for manufacturing a composition of laundry detergent dried by heat generated by neutralizing an acid component with a

base component without an additional drying process, wherein the method comprises steps of (Sl) preparing an acidic form of water-soluble polymer and an anionic

surfactant as the acid component, and an alkaline builder as the base component; (S2)

adding 0.1 to 15 parts by weight of the acidic form of the water-soluble polymer and 5 to 20 parts by weight of the anionic surfactant in combination with 10 to 70 parts by

weight of the alkaline builder to a mixer; (S3) homogenously mixing the components of

the step (S2) added to the mixer; and (S4) mixing the coated organic acid prepared

previously.

The present invention is based on a surprising fact that, if a water-soluble

organic acid capable of including calcium and/or magnesium ions present in hard water

is used instead of water-insoluble substances such as zeolite and others generally used as

the water softener, possibility that calcium carbonate and others remain in clothes after

laundering is very low since the softening rate of the hard water is highly rapid, and also

the touch feel of clothes may be significantly improved due to low possibility that the

water softener itself remains in clothes after laundering. The present invention is also

based on a surprising fact that, if a coated organic acid is used instead of the organic

acid itself, the organic acid of the detergent composition can be prevented from being in

contact with alkaline substances such as alkaline builder and others generally included

in the detergent composition to prevent neutralization reaction, and therefore its stability

can be improved, and also the detergent composition can maintain the washing effect

such as the improved touch feel of clothes after laundering since a softening ability of

the organic acid, for example an ability of including ions can be maintained during its storage.

The present invention is also based on the fact that neutralization reaction of acid

and base can be used to manufacture a powder detergent. The detergent composition

can be dried using heat generated in some of the neutralization reaction, and also a

powder detergent, and preferably a low-density powder detergent can be manufactured using bubbles generated by the gas formed in the particle by means of the neutralization reaction.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention provides a composition of laundry detergent capable of

improving touch feel of clothes after laundering and preventing color tones of clothes

from being discolored, characterized in that the composition of laundry detergent

includes (a) 0.1 to 15 parts by weight of an acidic form of water-soluble polymer; (b) 5

to 20 parts by weight of an anionic surfactant; (c) 10 to 70 parts by weight of an alkaline

builder; and (d) 0.5 to 20 parts by weight of an organic acid coated so that it can be

separated from the alkaline builder.

The term "touch fell", as used herein, means a feeling that persons feel when

they put on or touch clothes after the clothes is laundered. The touch feel may be

generally presented as a value measured using a Kawabata system. The Kawabata

system is often used when the touch feel of clothes is measured because it has been

known that the measured value is relevant to the satisfaction index which people feel.

The composition of laundry detergent of the present invention includes (a) 0.1 to

15 parts by weight of an acidic form of water-soluble polymer. The preferred acidic

form of water-soluble polymer may be at least one compound selected from the group

consisting of acrylic acid polymer, maleic acid polymer, methyl methacrylic acid

polymer, α-hydroxylic acid polymer, tetramethylene-l,2-dicarboxylic acid polymer,

4-methoxytetramethylene 1 ,2-dicarboxylic acid polymer and copolymers thereof. In

one preferred embodiment of the present invention, the acidic form of water-soluble polymer has an advantage that particles of the powder detergent are formed by

neutralizing basic materials with the polymer's carboxylic acid, which is coupled with

side chains of the polymer in the acidic form. Also, the structure of the bubble pores

made from the gas generated in the neutralization reaction can be maintained since the

physical properties of the polymer can maintain the shape of the particle when its

moisture is lost. Also, 0.1 % (w/w) aqueous solution of the acidic form of the

water-soluble polymer preferably has a pH value of 1 to 3.

Also, the composition of laundry detergent of the preset invention includes (b) 5

to 20 parts by weight of an anionic surfactant. The anionic surfactant plays a role of

generating bubbles in the powder detergent by neutralizing an alkaline builder with the

aforementioned acidic form of the water-soluble polymer as described later, as well as a

role of a detergent. Anionic surfactants generally used in compositions of laundry

detergent may be used as the anionic surfactant of the present invention. In particular,

lauryl benzene sulfonic acid, α-olefin sulfonate, sodium lauryl sulfate, sodium lauryl

ethoxylated sulfate and mixtures thereof may be used as the anionic surfactant. Lauryl

benzene sulfonic acid, which has a good physical property and is able to reduce density

of the powder detergent, may be preferably used as the anionic surfactant. The

contents included in the composition may be suitably adjusted within the

aforementioned range, depending on the desired density of the composition of laundry

detergent.

Also, the composition of laundry detergent of the present invention includes (c)

10 to 70 parts by weight of an alkaline builder. Sodium carbonate (soda ash), Sodium

bicarbonate (bicarbonate of soda), sodium sulfate (sulfate of soda) and mixtures thereof may be used as the alkaline builder. Generally, the alkaline builder generally used in

the powder detergent may reduce the possibility of generating the color-migration in

clothes, which may be generated due to its high pH value when the clothes is laundered

at high temperature, because pH of the powder detergent is prevented from being

increased through the suitable combination of the alkaline builders. In addition of the

role mentioned above, in the present invention, the alkaline builder plays a role of

carrying out the neutralization reaction with the acidic form of the water-soluble

polymer and the anionic surfactant. Especially, density of the powder detergent may

be adjusted by suitably adjusting the contents of the alkaline builders because the

density of the produced composition of laundry detergent may be varied depending on

the contents of the alkaline builders. That is, pores are made from bubbles generated

by gas such as carbon dioxide and moisture generated in the neutralization reaction

between the acidic substance such as the acidic form of water-soluble polymer and the

anionic surfactant and the alkaline substance such as the alkaline builder, as described

above. Then, increase of the pores allows the composition of laundry detergent to have

an excellent solubility in cold water and to be manufactured at a low density such that

remnants is not present in clothes after laundering.

Also, the composition of laundry detergent of the present invention includes (d) 0.5 to 20 parts by weight of an organic acid coated so that it can be separated from the

alkaline builder. The composition of laundry detergent of the present invention

includes the organic acid, which has an ability to include ions and is easily dissolved in

water, instead of insoluble zeolite generally used as the water softener. The organic acid used in the composition of the present invention is water-soluble, and therefore it shows very low possibility that calcium carbonate and others remain in clothes after

laundering since the softening rate of hard water is highly rapid, and it may also

significantly improve the touch feel of clothes after laundering due to low possibility

that water softener itself remains in clothes after laundering, and prevent calcium

carbonate and zeolite from adhering to and discoloring the clothes. Also, the organic

acid can lower the possibility of the color-migration which may be generated in clothes

due to high pH when clothes are laundered at high temperature since it functions to

reduce pH of the detergent composition.

The materials, which are composed of water-soluble multivalent carboxylic

acids and has an ability to include ions, such as citric acid anhydrous, citric acid

monohydrate, EDTA, N-hydroxyethylenediamine triacetic acid, nitrilotriacetic acid,

1,3-propylenediamine tetraacetic acid, succinic acid, fumaric acid, maleic acid,

1,2,3,4-cyclopentane tetraacetic acid, O-carboxymethyltaltronic acid,

O-carboxymethyloxysuccinic acid, tartaric acid, glutamic acid and so on may be used as

the organic acid included in the composition of laundry detergent of the present

invention, but is not limited thereto.

In one preferred embodiment of the present invention, the organic acid included

in the composition of laundry detergent is in an acidic form, and therefore should be suitably separated from alkaline components of the detergent composition. If the

organic acid is not suitably separated from the alkaline components, the organic acid

may react with the alkaline components along with moisture in the air to form caking,

resulting in deterioration of the washing effect. Accordingly, the stability of the

composition of laundry detergent may be improved during its storage if the separated organic acid is used in the composition, and therefore washability of the composition of

laundry detergent may be maintained during its storage. Methods generally used in the

art pertaining to the present invention may be used as the method for separating the

acidic components from the basic components. The composition of laundry detergent

of the present invention includes a coated organic acid so that the coated organic acid

can be separated from the alkaline components. The term "coating", as used herein,

means that the aforementioned organic acid is surrounded or mixed with coating

materials so that the organic acid can be separated from the alkaline components by

coating materials. Preferably, the coated organic acid of the present invention is

completely coated so that it can be completely prevented from being in contact with the

alkaline components, but it does not necessarily need to be completely separated from

the alkaline components if a partially coated organic acid complies with the spirit and

scope of the invention. That is, the present invention relates to the composition of

laundry detergent including the organic acid modified and handled so that it can be in

less contact with the alkaline components in the composition. Coating thickness of the

coated organic acid is more preferably 3-50 urn, considering the storage stability and the

washability of the composition of laundry detergent.

Silica compound, porous starch lysate, polyvinylpyrrolidone, carboxymethylcellulose and so on may be used as the coating material for coating the

organic acid of the present invention. If the silica compound is used as the coating

material, it has advantages that the detergent has an excellent flowability of particles and

the particles are not aggregated for an extended storage period. If polyvinylpyrrolidone

is used as the coating material, it has an advantage that another color-migration inhibitor does not need to be added. Also, porous starch lysate has an advantage that it is not

completely dissolved in water, and able to prevent contaminants from being reattached.

If the silica compound is used as the coating material, it preferably has a specific gravity

of 0.05 to 0.5 g/ml, and more preferably a DOP absorption value of at least 200 ml/100

g-

In one preferred embodiment of the present invention, the organic acid may be

first treated with a binder component before it is coated so at to separate the organic acid

effectively. For example, the coated organic acid of the present invention may be

manufactured by coating the outside of the organic acid with the coating materials such

as the silica compound when the organic acid is thoroughly mixed with the binder

component to coat the organic acid around.

Hydrophilic materials such as non-ionic surfactant, polyethyleneglycol, etc.

and/or hydrophobic materials such as silicon compound, fatty acid, etc. may be used for

the binder component. Preferably, at least one material selected from the group

consisting of alkyl ethoxylate having 5 to 20 mol of ethyleneoxide mole number,

polyethylene glycol having 400 to 20,000 mol of ethyleneoxide mole number, silicon

compound and fatty acid may be used as the binder component. If the silicon

compound is used as the binder component, it has an advantage that an additional use of antifoamer does not need.

Also, the composition of laundry detergent of the present invention may further

include 5 to 20 parts by weight of a non-ionic surfactant. The non-ionic surfactant

generally used is present in the form of the liquid phase, the density of the powder

detergent is closely affected by its total content. Preferably, the non-ionic surfactant has a content of 5 to 20 parts by weight since its manufacturability may be reduced at

higher content than the range, and its washability may be lowered at lower content than

the range. Non-ionic surfactants used in laundry detergent compositions may be

generally used in the present invention, and it includes, for example, polyoxyethylene

alkyl ether, coconut diethanolamide, fatty acid alkanolamine, amine oxide, alkyl

polyglucoside, methyl polyethylene alkyl ether, sugar ether, etc.

Also, the composition of laundry detergent of the present invention may include

the water-insoluble water softener in order to aid to formulate powder detergent

particles without departing from the spirit and scope of the invention. Zeolite

generally used may be used for the water softener, and p-type zeolite with small

particles is preferably used in the aspect of its residual property in clothes. However,

the zeolite is preferably used at a minimum content since the remnant of the zeolite

should be present at a minimum level to improve the touch feel.

Also, the composition of laundry detergent of the present invention may further

include 0.3 to 10 parts by weight of other various additives without departing from the

spirit and scope of the invention. The other additives may include a proteolytic

enzyme (protease, etc.) for removing contaminant proteins, a lipolytic enzyme (lipase,

etc.) for removing contaminant lipids, a carbohydrolytic enzyme (amylase, etc.) for removing contaminant foods, a cellulolytic enzyme (cellulase, etc.) for removing fluff of

cotton fibers, fluorescent dye such as biphenyls, stylbenes, etc., and an color-migration

inhibitor for preventing the dye, decomposed out of the fibers, from being reattached to

other fibers, or preventing the detached contaminants from being reattached to the others.

Each of the proteolytic enzyme, the lipolytic enzyme, the carbohydrolytic enzyme and the cellulolytic enzyme preferably has a content of 0.01 to 1 parts by weight, the

fluorescent dye preferably has a content of 0.1 to 1 parts by weight, and the migration

inhibitor preferably has a content of 0.5 to 5 parts by weight.

The present invention also provides a manufacturing method capable of

manufacturing the composition of laundry detergent, and preferably a method capable of

manufacturing the low-density composition of laundry detergent without an additional

drying process. The term "low density", as used herein, means that apparent density

including bubbles among the particles is 0.6 g/ml or less. The present invention

provides a method for manufacturing the composition of laundry detergent dried by heat

generated by neutralizing the acid component with the base component without an

additional drying process, in which the method includes steps of (Sl) preparing the

acidic form of water-soluble polymer and the anionic surfactant as the acid component,

and the alkaline builder as the base component; (S2) adding 0.1 to 15 parts by weight of

the acidic form of the water-soluble polymer and 5 to 20 parts by weight of the anionic

surfactant in combination with 10 to 70 parts by weight of the alkaline builder to a

mixer; (S3) homogenously mixing the components of the step (S2) added to the mixer;

and (S4) mixing the coated organic acid prepared previously.

The present invention uses a principle that the powder detergent is manufactured by implementing granulization of the powder detergent in the neutralization reaction of

the acid with the base, followed by drying the granulized detergent composition using

heat generated in some steps of the neutralization reaction, and also forming the pores

inside the particles by the gas bubbles formed in the particle by means of the

neutralization reaction. The pores have an advantage of improving the solubility (especially, solubility in cold water) since they prevent the residuals from remaining in

clothes upon laundering. As described above, the manufacturing method of the present

invention is very simple and economical since it does not need a heating step of drying

the powder, unlike the conventional methods for manufacturing the low-density

composition of laundry detergent, that is, because the counter-flow spray dryer, the

steam-blast mixer, etc. does not need to be used to manufacture the low-density powder

detergent.

Hereinafter, preferred embodiments of the present invention will be described in

detail referring to the accompanying drawings. Therefore, the description proposed

herein is just a preferable example for the purpose of illustrations only, not intended to

limit the scope of the invention, so it should be understood that other equivalents and

modifications could be made thereto without departing from the spirit and scope of the

invention.

Example 1 (Preparation of Coated Organic Acid) Citric acid was used as organic acid to prepare coated organic acid. The coated

organic acid was manufactured by mixing 90 kg of citric acid anhydrous with 4 kg of

polydimethylsiloxane, which is the silicon compound used as the binder component, in

the mixer for about 1 hour, followed by adding and mixing 6 kg of silica as the coating component.

Examples 2 and 3 and Comparative examples 1 and 2 (Preparation of

Composition of Laundry Detergent)

Compositions of Examples 2-3 and Comparative examples 1-2 were

manufactured by simply mixing the components using a high-speed mixer, based on the components and the contents listed in the following Table 1. In particular, the

compositions were manufactured by the conventional method including step of mixing

all components except other additives and the coated organic acid to prepare granular

powder, followed by mixing the granular powder with other additives and the coated

organic acid.

Table 1

In the Table 1, fluorescent dye is Tinopal CBS-X (Ciba Specialty Chemicals

Inc.), a proteolytic enzyme is Savinase 12.0T (Novozymes), a cellulolytic enzyme is

Carezyme 900T (Novozymes), and a carbohydrolytic enzyme is Termamyl 120T (Novozymes).

Stability Evaluation

In order to evaluate whether or not the coated organic acid is stably maintained

over time in the composition of laundry detergent of the present invention, the coated organic acid was mixed with soda ash, and then it was evaluated whether or not caking

is generated over time. The soda ash is a representative alkaline substance amongst the

detergent components that can raise an acid/base reaction. If the caking does not

appear some time after the coated organic acid is mixed with the soda ash, it is

considered to be a stable substance capable of preventing the caking. Accordingly, in

the present invention, the coated organic acid prepared previously in the Example 1 and

the soda ash powder were mixed at a ratio of 1 :3, namely 100 g of the coated organic

acid and 300 g of the soda ash, kept at 30 ^°C in a thermohygrostat with 60% relative

humidity for 1 week, and then the content of residue on the 12mesh sieve was calculated

to measure how many caking is formed. As a control of this experiment, 100 g of the

uncoated organic acid and 300 g of the soda ash were added under the same conditions

as described above. The results are listed in Table 2.

Table 2

As seen in Table 2, it was revealed that the uncoated organic acid reacts with the soda ash to form the caking, and then its clusters get larger, resulting in a relatively

increased amount of the residue on the 12-mesh sieve. In the aforementioned example,

it was seen that the composition of laundry detergent of the present invention is stable in

an actual product if the residue on the 12-mesh sieve is generated at a level of less than 10 %. Evaluation of Touch Feel

Washability of the composition of laundry detergent prepared in the Examples 2

and 3 and the Comparative examples 1 and 2, generally conducted by the consumers,

was measured under the drum-type washing conditions (Washing temperature: 40 ^°C ,W

time: 40 minutes, Rinsing: 3 times, Amount of the laundry: 3 Kg, Quantity of the

detergent: 35 g, Test fabrics: Length x Width = 120 cm x 90 cm (Korean Apparel

Industry Association: Standard fabrics) x 2 sheets), and then evaluation items of a

Kawabata system such as KOSHI (Stiffness), SHARI (Crispness), FUKURAMI

(Fullness and Softness) and HARI (Anti-drape Stiffness = Spreading) were measured for

the test fabrics, and the resultant values are assigned to the equation to correspond to

men and women' clothes. As a result, the total hand value (T.H.V) was obtained, as

listed in Table 3.

Table 3

As seen in Table 3, it was revealed that T.H.V. of the Examples are good,

compared to the Comparative examples. It was found that T.H.V. measured by the

Kawabata System is generally relevant to the value measured by the actual consumers

by measuring the touch feel on the basis of a full mark of 5. It was proved that such a

change of the touch feel appears because the composition of laundry detergent of the

present invention shows a low possibility that the water-insoluble substance such as zeolite, etc. remains in clothes, or calcium carbonate is attached to clothes, and also has

a low pH.

Evaluation of Washability

Washability, which is one of basic properties of the detergent, was evaluated.

The evaluation of washability was measured using a washing machine with the same

conditions as described in the Evaluation of Touch Feel, and general city water was used.

The washing conditions are identical to those of the evaluation of the touch feel

(Washing temperature: 40 ^°C,W time: 40 minutes, Rinsing: 3 times, Amount of the

laundry: 3 Kg, Quantity of the detergent: 35 g, Test fabrics: Length x Width = 120 cm x

90 cm (Korean Apparel Industry Association: Standard fabrics) x 2 sheets), and the

evaluation of washability on twenty sheets of the soiled fabrics (5 x 5 cm) was carried

out using synthetic wet soiled fabrics manufactured by Japan Committee on Laundry

Science. WB values, which represent whiteness of the soiled fabrics, were measured using a colorimeter before and after laundering. 35 g of the compositions of laundry

detergent prepared in the Examples and the Comparative examples each were added to

the washing machine, and measured by attaching the soiled fabrics to the actual cotton

T-shirts. The soiled fabrics, washed and then dried with a standard course of the

washing machine, were dried in a thermohygrostat (25 ^°C , 20 % RH) for 1 day, and then

ironed to measure WB values using the same colorimeter. The resultant WB values

were substituted into a Kubelka-Munk equation, presented in following Equation 1, to

calculate washability. The result is listed in following Table 4. Equation 1

[( i -/r)/2/y( i -/r)/2/g

Washability (%) = x 100

[ ( \ -R:)/2R_r( \ -R_o ²)/2R_u]

In the Equation 1, R_s represents surface reflectivity of the soiled fabrics, R₀

represents surface reflectivity of the fabrics after removal of the contaminants, and R₀

represents surface reflectivity of the white fabrics. Table 4

Comparative Comparative

Item Example 2 Example 3 example 1 example 2

Washability (%)

(Japan Committee on Laundry 80.55 81.82 79.40 80.01

Science: Soiled fabric)

As seen in Table 4, it was revealed that the compositions of laundry detergent

prepared in Examples 2 and 3 showed a higher washability, compared to the

composition of laundry detergent prepared in Comparative examples 1 and 2, which

results from the ability of the acidic form of the water-soluble polymer to prevent the

contaminants from being reattached, and synergistic effect by the organic acid. Also, it

was considered that the composition of the present invention using the organic acid has

an improved washability since it has a more rapid dissolution rate than the conventional

composition of laundry detergent using the zeolite, etc.

INDUSTRIAL APPLICABILITY

As described above, the composition of laundry detergent according to the present invention is useful to have very low possibility that calcium carbonate and others remain in clothes after laundering since the softening rate of hard water is highly

rapid if the coated organic acid is used instead of the conventional water-insoluble water

softener, and it is also useful to significantly improve the touch feel of clothes after

laundering and to maintain original colors of clothes with color tones due to low

possibility that water softener itself remains in clothes after laundering. Also, the

composition of laundry detergent according to the present invention is stable, and

therefore can maintain the washability during its storage since the neutralization reaction

is inhibited during its storage by preventing the organic acid from being in contact with

the alkaline components, and therefore caking phenomenon is inhibited. Also, the

manufacturing method of the present invention does not need the additional drying

process so as to manufacture the powder detergent, as well as it is very simple and

economical, and it is also easy to manufacture the low-density powder detergent.

The present invention has been described in detail. However, it should be

understood that the detailed description and specific examples, while indicating

preferred embodiments of the invention, are given by way of illustration only, since

various changes and modifications within the spirit and scope of the invention will

become apparent to those skilled in the art from this detailed description.

Claims

What is claimed is:

1. A composition of laundry detergent comprising: (a) 0.1 to 15 parts by

weight of an acidic form of water-soluble polymer; (b) 5 to 20 parts by weight of an

anionic surfactant; (c) 10 to 70 parts by weight of an alkaline builder; and (d) 0.5 to 20

parts by weight of an organic acid, wherein the organic acid is coated so that it can be

separated from the alkaline builder.

2. The composition of laundry detergent according to claim 1,

wherein the organic acid is selected from the group consisting of citric acid anhydrous, citric acid hydrate, EDTA, N-hydroxyethylenediamine triacetic acid,

nitrilotriacetic acid, 1,3-propylenediamine tetraacetc acid, succinic acid, fumaric acid,

maleic acid, 1,2,3,4-cyclopentane tetraacetic acid, O-carboxymethyltaltronic acid,

O-carboxymethyloxysuccinic acid, tartaric acid and glutamic acid.

3. The composition of laundry detergent according to claim 1 , wherein the organic acid is coated with at least one coating material selected

from the group consisting of silica compound, porous starch lysate,

polyvinylpyrrolidone and carboxymethylcellulose.

4. The composition of laundry detergent according to claim 1 ,

wherein the organic acid is firstly mixed with at least one binder selected from

the group consisting of alkyl ethoxylate having 5 to 20 mol of ethyleneoxide mole number, polyethylene glycol having 400 to 20,000 mol of ethyleneoxide mole number,

silicon compound and fatty acid, and secondly coated with at least one coating material

selected from the group consisting of silica compound, porous starch lysate,

polyvinylpyrrolidone and carboxymethylcellulose.

5. The composition of laundry detergent according to claim 1, wherein the

coating thickness of the coated organic acid ranges from 3 to 50 um.

6. The composition of laundry detergent according to any of claims 1 to 5,

wherein the acidic form of water-soluble polymer is at least one selected from

the group consisting of an acrylic acid polymer, a maleic acid polymer, a

methylmethacrylic acid polymer, an α-hydroxylic acid polymer, a

tetramethylene-l,2-dicarboxylic acid polymer, a 4-methoxytetramethylene

1 ,2-dicarboxylic acid polymer and copolymers thereof.

7. The composition of laundry detergent according to any of claims 1 to 5, wherein the anionic surfactant is at least one selected from the group consisting

of lauryl benzene sulfonic acid, α-olefin sulfonate, sodium lauryl sulfate and sodium

lauryl ethoxylated sulfate.

8. The composition of laundry detergent according to claim 7, wherein the

anionic surfactant is lauryl benzene sulfonic acid.

9. A method for manufacturing a composition of laundry detergent dried by

heat generated by neutralizing an acid component with a base component without an

additional drying process, comprising:

(S 1 ) preparing an acidic form of water-soluble polymer and an anionic surfactant

as the acid component, and an alkaline builder as the base component;

(52) adding 0.1 to 15 parts by weight of the acidic form of water-soluble

polymer and 5 to 20 parts by weight of the anionic surfactant in combination with 10 to

70 parts by weight of the alkaline builder to a mixer;

(53) homogenously mixing the components of the step (S2) added to the mixer;

and

(54) mixing a coated organic acid, prepared previously.

10. The method for manufacturing the composition of laundry detergent

according to claim 9, wherein the composition of laundry detergent has a low density.