Cationic Softeners

Cationic softeners are ionic molecules that have a positive charge on the large part of the molecule. The important ones are based on nitrogen, either in the form of an amine or in the form of a quaternary ammonium salt. The amine becomes positively charged at acidic pHs and therefore functions as a cationic material at pH below 7. Quaternary ammonium salts (hereafter referred to as QUATS), retain their cationic nature at all pHs.

An important quality of cationic softeners is that they exhaust from water onto all fibers. Cationics are highly efficient softeners. The ionic attraction causes complete exhaustion from baths and the orientation on the fiber surfaces allows a monolayer to-be as effective as having more lubricant piled on-top.

R

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/ / / / / / / / / / / / / / /  FIBER SURFACE  \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

Figure Adsorption on Fiber Surface

Amine Functional Cationic Softeners:

They exhaust and become excellent softeners under acidic conditions. The cationic charge on a given hydrophobe is proportional to the number of amino groups, therefore the attraction of the cationic portion to the fiber surface increases as the number of amine groups’ increase.

i. Primary Fatty Amines

ii. Difatty Amines

iii. Fatty Diamines

iv. Cationic Amine Salts:

• • • Fatty Aminoesters
    • Fatty Amidoamides
    • Quaternary Ammonium Salts

Quaternary ammonium salts are extremely important fatty acid derivatives. The quat’s cationic charge is permanent, being maintained at all pHs. In addition to imparting softness, quats rduce the static charge on synthetic fabrics and inhibit the growth of bacteria. Quats are therefore used as antistats and germicides as well as softeners. Cationics containing two C18 fatty tails attached to the nitrogen impart very soft, fluffy hand to textile produces.

1.Synthesis of Monofatty Quats

 

Cl– R – NH2   +   3CH3Cl                                                           R – N (CH3)3

 

2. Synthesis of Difatty Quats

3. Synthesis of Monofatty Quats

 

CH2CH2NH2					CH2CH2NH2
	N––CH2						CH3–N––CH2
R–C				+ CH3Cl		R–C					Cl–
	N––CH2							N––CH2

Advantages of Cationic Softener

• • Cationic softeners impart very soft, fluffy, silky hand to most all fabrics at very low levels of add-on.
  • Cationics will exhaust from dyebaths and laundry rinse baths making them very efficient materials to use.
  • Cationics will exhaust from acidic solutions.
  • Cationics improve tear resistance, abrasion resistance and fabric sewability.
  • Cationics also improve antistatic properties of synthetic fibers.
  • They are compatible with most resin finishes.
  • They are good for fabrics to be napped or sueded.

Disadvantages of Cationic Softener

• • They are incompatible with anionic auxiliary chemicals.
  • They have poor resistance to yellowing.
  • They may change dye shade or affect light fastness of some dyes.
  • They retain chlorine from bleach baths.
  • They adversely affect soiling and soil removal and may impart unwanted water repellency to some fabrics.

 

Nonionic Softeners

They are not very good softener, however it can be used with any composition of the bath as they are nonionic. Now a days one of its class silicone softeners have been used extensively.

Nonionic softeners can be divided into three subcategories,

• ethylene oxide derivatives,
• hydrocarbon waxes based on paraffin or polyethylene.
• Silicones.

Dispersions with anionic, nonionic and cationic character are made by selecting appropriate auxiliary emulsifier. Selecting an emulsion with the roper ionic character is important otherwise the finishing bath will become unstable and break out.

Silicone Chemistry:

Silicones are Polysiloxane Polymers and fall under the class of materials known as organometallics. The element silicon is considered a metal and is found is abundance in nature as silica, SiO₂. Silicon resembles carbon in that it is tetravalent and forms covalent bond with other elements. Simple tetravalent compounds are called silanes. Silicon forms a stable covalent bond with carbon leading to a class of materials known as organosilanes.

1. Formation of Organofunctional Reactive Silanes:

CH₃

        Si + CH₃Cl    ====>                   SiCl +      CH₃Si (Cl)₃ +          CH₃Si (Cl)₂H +        (CH₃)₃ SiCl

                                                                                                      |                                   |

                                                                CH₃                CH₃

                                                                  [I]                   [II]                             [III]                        [IV]

Compound Name:

[I]          Dimethylchlorosilane

[II]       Methylchlorosilane

[III]    Methylhydrogendichlorosilane

[IV]    Trimethylchlorosilane

Silicone Softeners

Four varieties of silicone polymers have found use as textile softeners. One variety is based on

• Dimethyl Fluids
• Methylhydrogen Fluids
• Amino Functional Silicones
• Epoxy Functional Silicones

a.Dimethyl Fluids:

Dimethyl fluids are mad from dimethyldichloro silane. Fluids are water clear and do not discolor with heat or age. They impart soft silky hands to fabrics. In addition to softening, dimethyl fluids render fabrics somewhat water repellent; however, being fluids, they are not durable.

CH3	CH3		CH3	CH3	CH3
n  Cl – Si – Cl +	2 Cl – SiCH3		CH3 – SiO	– SiO	Si – CH3
CH3	CH3		CH3	CH3	n   CH3

CH₃                  CH₃ CH₃            CH₃ CH₃            CH₃ CH₃                  CH₃

 

Si                     Si                     Si                     Si

 

O                     O                     O                     O                     O

/ / / / / / / / / / / / / / /  FIBER SURFACE  \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

 

Figure: Orientation of Dimethyl Fluids on Fiber Surface

b.Methylhydrogen Fluids:

Methylhydrogndichlorosilane offers a route for making a linear polysiloxane This offer a way of improving durability.

		H2O	CH3		CH3
CH3 – SiHCl2	+ (CH3)2SiCl2	–	SiO	–	SiO–
			CH3	a	CH3	b

c.Amino Functional Silicones:

Amino functional silicones are mad by incorporation the appropriate organofunctional chlorosilane to the reaction mix. Amino functional silicones become cationic at acid pHs and exhaust from aqueous baths.

d.Epoxy Functional Silicones:

Epoxy functional groups can be incorporated into silicone polymers by incorporating the appropriate group into the silicone polymer back bone These softeners are mor durable to repeated laundering.

Advantages of Silicon Softener

• Silicones are water clear oils that are stable to heat and light and do not discolor fabric.
• They produce a slick silky hand and are referred for white goods. They improve tear and abrasion resistance and are excellent for improving swing properties of fabrics.
• Amino functional silicones improve DP performance of cotton goods.
• Epoxy functionals are more durable.

Disadvantages of Silicon softener

• The silicones are water repellent which make them unsuitable as towel softeners.
• Silicones are expensive compared with fatty softeners.
• Amino functional silicone discolors with heat and aging.
• They may interfere with redyeing when salvaging off quality goods.

Amphoteric softener

Amphoteric softener have long alkyl chain which contain both acidic and basic group and their nature depends on pH. At

Low pH:   cationic

pH 7:         nonionic

high pH:   anionic

They are expensive and used in novelty products in specialist application. Generally they are not used in textile industry but cosmetic industry.

The products are based on

• Substituted amino acids: R-⁺NH₂CH₂CH₂COO^–
• Sulphobetains: R₃N+ (CH₂)_n-SO₃^–
• Betains: R CONH-C₃H₆N⁺(CH₃)₂CH₂COO^–
• Imidazolines

Trade name of softener

BASF

• Basosoft EUK (cationic)
• Basosoft FA535 (cationic but mixed with silicone softener)
• Siligen FA210 (normal silicone)

Cationic Softeners

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