Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
  • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
  • D06L4/20—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen
  • D06L4/22—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents
  • D06L4/24—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents using chlorites or chlorine dioxide
  • D06L4/26—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents using chlorites or chlorine dioxide combined with specific additives
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
  • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
  • D06L4/20—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen
  • D06L4/22—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents
  • D06L4/23—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents using hypohalogenites

Definitions

• the present invention relates to chemical bleaching processes adapted for bleaching most various materials, such as natural, artificial or synthetic fibres mainly of cotton, fiax, hemp, jute, nylon, perlon, or others, paper, etc., by destroying the coloring matter through oxidation, the bleaching effect being obtained by virtue of a reaction between an acid and a bleaching agent, generally a chlorine compound, under the action of heat.
• a bleaching agent generally a chlorine compound
• Such a bleaching treatment is often carried out on a product to be bleached such as, for instance, a fabric which has just been subjected to another previous treatment, such as size removing, scalding or other treatment, so that it is impregnated with a treating agent, the presence of which in the fabric necessitates a preliminary treatment before it is possible for the product to be subjccted to the bleaching treatment.
• a product to be bleached such as, for instance, a fabric which has just been subjected to another previous treatment, such as size removing, scalding or other treatment, so that it is impregnated with a treating agent, the presence of which in the fabric necessitates a preliminary treatment before it is possible for the product to be subjccted to the bleaching treatment.
• the bleaching operation is then effected, for instance by means of chloride, by introducing the fabric into a bath containing chlorite and an acid such as formic acid. After being impregnated, the fabric is squeezed and introduced into a treating chamber where it is exposed to heat which brings about a reaction between the chlorite and the acid, leading to the formation of chlorine dioxide constituting finally the oxidising agent which ensures the bleaching effect. It is further to be noted that this reaction must be controlled in such manner as to prevent the formation of chlorate which attacks the fibres, a condition which is very difficult to attain even by providing an excess of acid.
• the main object of the present invention is to considerably simplify the chemical bleaching treatment while reducing the amounts of the reagents involved.
• the bleaching process according to the invention consists in first impregnating throughout, i. e. from its surface to its very core, the material to be bleached with an acid, then impregnating said material over its surface with a bleaching agent such as a chlorine compound, and then exposing to heat the material thus impregnated to the core thereof with an acid and over its surface with a bleaching medium.
• a bleaching agent such as a chlorine compound
• the material to be bleached and impregnated with the basic reagent is introduced into a neutralizing bath containing an excess of acid beyond the amount which is necessary for the desired neutralization and sufficient for affording the desired acid impregnation to the core, the material to be bleached being then impregnated over its surface with a bleaching agent and then exposed to heat.
• the acid impregnation to the very core of the material is ensured by passing the material through a bath constituted by a weak acid, such as formic acid, phosphoric acid or the like, and maintained up to its boiling temperature or a temperature near the latter.
• a weak acid such as formic acid, phosphoric acid or the like
• the superficial impregnation with a bleaching agent is effected by having the treated material previously impregnated to the core thereof with an acid passed through a bath constituted by water containing, preferably, per liter, 5 to 30 grams of bleaching agent such as chlorine, hypochlorite or other chlorine compound, according to the state of the product to be bleached.
• a bleaching agent such as chlorine, hypochlorite or other chlorine compound
• the material to be bleached is squeezed down until it contains about 70% of liquid based on its weight when dry, after having passed through a bath for being acidified to the core.
• the product to be bleached is squeezed down until it contains about to of liquid based on its weight when dry, after its passage through the bleaching bath.
• the scalded fabric impregnated with caustic soda is caused to pass through an acid bath adapted to neutralize said caustic soda.
• this neutralization is not effected by means of a strong acid such as sulphuric acid, but, in view of the subsequent bleaching operation, by means of a weak acid, such as formic acid, phosphoric acid or other acid.
• the bath may contain for example 20 cubic centimeters of formic acid per liter.
• the bath is brought, according to another feature of the invention, up to its boiling temperature or a temperature near the latter, which yields to the reaction the necessary strength.
• the caustic soda When coming into contact with this nearly boiling acid, the caustic soda is instantaneously neutralized and soda formate is formed. It is further to be noted that the bath is controlled in such a manner that there always remains an excess of acid subsequent to the neutralization of the caustic soda.
• the fabric is impregnated to its very core with formic acid at the exit of the bath. It is then squeezed down until it contains about 70% of liquid based on its weight when dry and introduced into a bath containing the bleaching agent.
• This bath is constituted, for instance, by Water containing, per liter, 5 to 30 grams of a bleaching agent such as soda chlorite, hypochlorite or other chlorine compounds, according to the state of the fabric, for instance according to the importance of the motes.”
• a bleaching agent such as soda chlorite, hypochlorite or other chlorine compounds, according to the state of the fabric, for instance according to the importance of the motes.
• This bath need not be heated. Furthermore, it may comprise an addition of formic acid, but this is not at all necessary.
• the fabric is squeezed down until it contains about 90 to 100% of liquid based on its weight when dry and introduced into a treating chamber where it is exposed to the action of heat.
• the chlorine dioxide formed by the reaction between the formic acid and the chlorite, or other chlorine compound, then brings about the desired destruction of the coloring material by oxidation thereof.
• the same acid namely the formic acid in the example contemplated, acts, first to neutralize the caustic soda and, second insures the formation of the chlorine dioxide, from chlorite.
• the size removing and the scalding operations are effected by means of a mixture of soda carbonate, of trisodium phosphate bleaching liquid (Javel water) and a wetting agent.
• the fabric impregnated with this mixture is passed into a bath of formic acid brought up to a temperature at least near the boiling temperature. Then the process is continued as in the preceding example.
• Bleaching liquid (Javel water) may also be used as a bleaching agent instead of the chlorite.
• the method may also be applied to a substance, cellulose or other, in a fiocky state.
• the impregnation with acid is not effected in a bath but in any other suitable manner, for example inside a vat filled up with the flocky material, and into which the acid is poured in order to impregnate the fiocky material to the core thereof prior to its superficial impregnation with a bleaching agent.

Landscapes

• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Treatment Of Fiber Materials (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Paper (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=9600092

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (7)

Family Cites Families (2)

• 1954
  • 1954-06-01 FR FR1105634D patent/FR1105634A/fr not_active Expired
• 1955
  • 1955-05-23 US US510501A patent/US2864662A/en not_active Expired - Lifetime
  • 1955-05-24 DE DED20524A patent/DE1061283B/de active Pending
  • 1955-05-27 GB GB15322/55A patent/GB781716A/en not_active Expired

Patent Citations (7)

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