Subject of the Invention and Technical Field

The invention relates to a synthesis method for an organic bleaching agent especially for bleaching denims in the textile sector. In particularly, the invention relates to a new synthesis method for peroxycarbonic acid and salts thereof, wherein the method provides a product in a high yield using a water-free process in which a low amount of solvents is used. The invention includes two different synthesis method: in situ methods and methods performed in a reactor.

State of the Art

Today, the denim fabrics are preferred and commonly used as they are both economic and comfortable. In particularly, there is a trend for the distressed appearance and different fashion effects. As there is a great need for the garments to be purchased by the consumers as a new article with a distressed appearance, bleaching of the fabrics are commercially important to create a visual effect of said distressed appearance. Rinsing processes are used to bleach and distress a denim fabric. Said rinsing processes are carried out using a pumice stone, enzymes and various chemicals. Generally, there is an increasing need for the denim products which are color faded (bleached) in combination with chemical processes.

Among the chemical methods used from past to present in order to fade or bleach denim materials in the textile sector are the bleaching methods using potassium permanganate, sodium hypochlorite, ozone, or an enzyme. The bleaching process (fading or superlaming) is a reduction reaction performed after stone washing or normal rinsing processes. In the state of the art, a neutralization process of good quality is required after a bleaching step using potassium permanganate and sodium hypochlorite. If residual chlorine is not removed after the bleaching processes performed using chloride-containing substances, such as sodium hypochlorite, in particularly the ones which are first dyed and then color faded may lead to a variety of allergies, swellings and irritations on the skin. Another drawback is that it is toxic for the biological treatment. Chlorinated hydrocarbons are both difficult to be biologically degraded and are ecologically toxic. Residual chlorine damages the environment.

Ozone bleaching is very important in that the troublesome and toxic chemicals are eliminated, ozone is used instead of hypochlorite, and no residue is left on the fabric. However, dizziness and respiratory failure may occur in case of a prolonged exposure to ozone.

In the state of the art, potassium permanganate and sodium hypochlorite are mainly used for denim bleaching processes. Said chemicals are quite harmful to health. There is an increasing demand worldwide for less harmful organic bleaching agent.

On the other hand, peroxy acids are acid compounds of formula below, which contains an acidic -OOH group. They are also known as peracids. They may be a derivative of mineral acid, especially sulphuric acid, or a peroxy derivative of the organic carboxylic acids. They have a strong oxidative characteristic.

Magnesium monoperoxy phthalate (abbreviated as MMPP) is a peroxy acid which is a good oxidative agent and has a strong disinfectant and bacteriside effect. It is preferred for the chemical syntheses, and the health and textile industry as it is dissolved in water easily. It is used on precise materials such as plastic and rubber equipment used in hospitals due to broad surface compatibility thereof. Magnesium monoperoxy phthalate has a molecular structure as follows.

In the state of the art, there are numerous patent document with regard to bleaching agents. One example is US patent document no.US4634551A, entitled “Bleaching compounds and compositions comprising fatty peroxyacids salts thereof and precursors therefor having amide moieties in the fatty chain”. Said document discloses bleaching compounds and compositions, which bleach the surfaces of the textile products in an effective and efficient manner with a bleaching solution at various temperatures. The bleaching compounds of the invention provide a peroxy acid having a polar amide bond on the hydrophobic chain when they are used in a bleaching composition.

The European patent document EP0106584A1, entitled “Bleaching compositions” discloses a bleaching composition. In particularly, a content which has an effective and efficient bleaching performance is disclosed. The inventive part is that is exhibits that performance in a broad range of stain class, temperature and pH. The content usually consists of a halogenated peroxybenzoic acid, or a salt thereof, and a bleaching activator.

US patent document US5089167A, entitled “Stable peracid bleaching compositions: organic peracid, magnesium sulfate and controlled amounts of water” discloses domestic fabric bleaching products. In particularly, dry bleaching products are disclosed, which is based on stabilized organic diperacid compositions and may contain enzymes. In an alternative of the invention, a stable peracid bleaching composition is disclosed, which comprises different granules containing a peracid called diperoxydodecanedioic acid. In a preferred embodiment, the composition comprises enzymes in addition to the peracid granules. In both embodiments, the peracid and exotherm controlling agents are combined in a granule for which the amount of water is carefully controlled, such that the peracid and the enzyme are stabilized.

In the state of the art, there are numerous studies on the textile bleaching agents, however, there are few studies on a peracid salt such as magnesium monoperoxy phthalate and the synthesis thereof. Accordingly, there is a need for textile bleaching agents which are less harmful to humans and the environment and is able to be obtained using an easier and higher efficiency process as compared to the state of the art. Technical Problems to be Solved by the Invention

The object of the invention is to provide a method for obtaining an aromatic organic peroxycarbonic acid which is the active ingredient, and the salts thereof.

An advantage of the synthesis method of the invention is that there is no water addition and the low amounts of solvent are used. Thus, a high efficiency reaction is carried out, and a product is obtained.

Another advantage of the synthesis method of the invention is to allow a cheaper production process.

A further advantage of the synthesis method of the invention is that the organic bleaching agent obtained from the synthesis exhibits a low toxicity. Thus, the living thing and environment issues in the relevant field are minimized.

Another advantage of the synthesis method of the invention is to allow in situ peroxycarbonic acid production. Thus, the synthesis of an organic bleaching agent may be performed in an easier way without a reactor.

Description of the Figures

Figure 1 is a flow chart of the process steps of the synthesis method in a reactor according to the invention.

Process Flow Chart to Help Describing the Invention

100- Placing ethyl acetate into a reactor,

110- Adding and mixing the phthalic anhydride,

120- Adding and mixing the magnesium hydroxide,

130- Adding and mixing the hydrogen peroxide,

140- Filtering and collecting the product, and 150- Drying.

Detailed Description of the Invention A method is intended to be provided, in which a product is obtained in an easier and more cost efficiently manner with a higher yield using the synthesis method of the invention as compared to the state of the art. Based on that basic object, the salts of the alkali metal bases and an aromatic organic anhydride compound are reacted in ethyl acetate used as a solvent by introducing an acid and hydrogen peroxide.

The inventive aspect of the invention is that the synthesis method of the invention does not include the addition of water and a low amount of solvent is used. In the synthesis method of the invention the aromatic organic anhydride compound is selected from any one of the compounds, such as phthalic acid, maleic acid, acetic anhydride, terephtalic acid, fenolic anhydride, glutaric anhydride, and the combinations thereof. In the synthesis method of the invention, an aromatic organic peroxycarbonic acid, the active ingredient, is obtained under the basic environment conditions. The basic environment conditions are realized with any one of magnesium, sodium, calcium and potassium salts of the citrates, oxides and hydroxides, or a combination thereof. Essentially, the aromatic organic anhydride compound and the salts of the alkali metal bases are reacted under these conditions, and thus, the organic peroxycarbonic acid is formed. The salts of the alkali metal bases which may be referred as the auxiliary chemicals may be any one of CaCCh, CaCaCU, NqbObH _d Og, NaOH, Mg(OH)2, or the mixtures thereof.

The invention generally relates to a peracid salt, or a method for synthesizing peroxycarbonic acid. The synthesis of magnesium monoperoxy phthalate is exemplified, but it is not limited thereto.

The process steps of the synthesis method in the reactor of the invention provide a flow chart as shown in Figure 1. Accordingly, an alternative of the synthesis method of the invention performed in the reactor comprises the following process steps.

Placing (100) ethyl acetate into a reactor,

Adding and mixing (110) the phthalic anhydride and the acid,

Adding and mixing (120) a basic salt,

Adding and mixing (130) the hydrogen peroxide, Filtering and collecting (140) the product, and

Drying (150).

The detailed description of these process steps is as follows.

Step of placing (100) ethyl acetate into a reactor

Firstly, the ethyl acetate is placed in the reactor which is pre-cooled preferably to 5-6 °C.

Steps of adding and mixing (110) the phthalic anhydride and the acid

In these steps, the phthalic acid is poured onto the ethyl acetate slowly. 25 units of phthalic anhydride per 100 units of ethyl acetate are used. Upon the addition of the phthalic anhydride, the mixing process is carried out manually, or using an equipment such as a stirrer. An acid is added to the mixture in order to run in a given pH range. In this step, any one of phthalic acid, benzoic acid, maleic acid, etc., or the combinations thereof are used as an acid. 55-80% by weight of acids per 100 units of product are used.

Steps of adding and mixing (120) a basic salt

In these steps, a basic salt is added to the mixture obtained after the phthalic anhydride and the acid are added and mixed (110). The basic salt may be an alkaline or alkaline earth metal and may be any one of CaCCh, CaCaCU, NqbObH _d Og, NaOH, Mg(OH)2, or the mixtures thereof. 4.8 units of magnesium hydroxide per 100 units of ethyl acetate are used for the synthesis of magnesium monoperoxy phthalate. Upon the addition of the basic salt, the mixing process is carried out manually, or using an equipment such as a stirrer.

Steps of adding and mixing (130) the hydrogen peroxide In these steps, upon the addition and mixing (120) of the basic salt, 0.5-2% by weight of hydrogen peroxide per 10 liters of a solvent are added to the mixture in a controlled manner and stirred manually, or using an equipment, such as a stirrer, for 24 hours.

Steps of filtering and collecting (140) the product

In these steps, the mixture obtained after the hydrogen peroxide is added and mixed (130) is transferred to a filtering system and filtered, and a product is collected.

Step of drying (150)

In this step, the product collected is transferred to an equipment, such as an oven, etc. and dried at a temperature of 25-45 °C. Preferably, the temperature control should be done in a drying process with moisture and a fan.

In the synthesis method of the invention, preferably 45-80% by weight of the organic anhydride and 15-50% of the basic salt are used. The reaction should be performed in a pH range of 1-5. The pH value may be adjusted with the mineral acids, or the organic acids, in particularly using the acids, such as phthalic acid, phosphoric acid, maleic acid, sulphuric acid, etc. at 20 °C.

In in situ alternative of the synthesis method according to the invention, the bleaching effect is increased with the salt of the sodium citrate and the auxiliary chemicals. Any one of the salts, like boric acid, borax pentahydrate, sodium tetraborate, etc., magnesium salts, and polymeric alcohol and carbohydrate derivatives, or the mixtures thereof may be used as an auxiliary chemical.

In in situ synthesis method of the invention, the anhydride molecule, the basic salts and the auxiliary chemicals are placed in a solid mixing reactor and mixed. The basic salts may be any one of magnesium, sodium, calcium and potassium salts of the citrates, oxides and hydroxides, or a combination thereof. Although there is no specific time for the mixing process, the mixing should be done until the homogenization is obtained. Finally, the homogeneous mixture is packaged. In said alternative synthesis method, preferably 45-80% of the aromatic anhydride, 10-50% of the basic salts, and 1-10% of the auxiliary chemicals are used. In the alternative synthesis method, the auxiliary chemicals are added in situ during any step of the process.

Upon in situ reaction, a mixture in the form of powder is obtained. An aqueous solution of the magnesium peroxyphthalate salt in a medium is obtained by mixing the solid mixture prepared with the aqueous hydrogen peroxide solutions and the activators in varying ratios before use. The peroxyphthalate salt obtained is applied to the denim fabric, and the organic bleaching is achieved. Industrial Applicability of the Invention

The product obtained by the synthesis method of the invention may be used for bleaching the denim products, especially in the textile sector. The synthesis method of the invention may easily applied in a laboratory, and a product with high yield may be obtained. According to the synthesis method of the invention, the production may be achieved by a process in a reactor, as well as powder mixture may be obtained in situ. An aqueous solution of the peracid salt in a medium is obtained by mixing said powder mixture with the aqueous hydrogen peroxide solutions and the activators in varying ratios before use. The peracid salt obtained is applied to the denim fabric, and the organic bleaching is achieved.