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68Djuraev Abdujalil, The scientific researcher Kadirov Tolqin, The scientific adviser: professor Tashkent Institute of Textile and Light Industry, Uzbekistan E-mail: [email protected]
Hydrophobization of shoe upper leather on the basis of new polymer composites and kinetics of absorption of moisture by leather
Abstract: Natural leathers possess valuable properties: good breathability, water vapor permeability and heat conductivity, they differ favorably from other materials in strength and elasticity.
However, leathers have essential disadvantages: high water permeability, poor water resistance. Water permeability of leather degrades performance properties of goods.
Hydrophobizators based on organosilicone compounds are highly effective. When applying they form a thin invisible hydrophobic film not affecting breathability of materials. This film has long life; it possesses chemical resistance, high- and low temperature stability, and high mechanical strength.
Keywords: Hydrophobizators, organosilicone, interfibrillary, polysiloxanes, polymer composites, leather.
Introduction. The military was the first to finished product on the other hand. Industrial and show interest in waterproof leathers. product safety means complete or partial replace-
Soldiers must be active in all situations, under all ment of organic high volatile substances by water weather conditions and on any terrain, including wet products that are more environmentally friendly. one. This primarily concerns footwear, because wet Consider the possibilities of modern water-based footwear is the source of many problems. materials for waterproof natural leather finishing.
More recently, manufacturers of common walk- The aim of hydrophobization is to improve the ing and sports shoes have also begun to show in- performance properties of leather without any decreasing interest in waterproof leathers because of terioration of its physical mechanical (strength) and the obvious benefits of watertight footwear. Follow- hygienic properties (breathability, water vapor per-ing the military manufactures of footwear for golf, meability) [5; 6]. In addition, it is desirable that the football, tourism and mountaineering have become hydrophobic effect does not reduce for a long time major consumers ofwaterproofleather. Waterproof during the use ofleather goods. leathers are also used in the production of sports One of the most promising and effective meth-gloves and high-quality sportswear. High water re- ods of obtaining leather with water-repellent propersistance leather is used with pleasure by well-known ties is its treatment with organosilicone oligomers designers to create collections of "ordinary" fashion [4; 7; 9; 10]. Treatment of siloxanes in organic sol-footwear in order to increase sales and attract new vents gives high hydrophobicity to leather. Leather customers. can be treated by siloxane coating using a spray gun
Thus, natural leather manufacturers have to or a brush. draw attention to the growing interest of shoemak- Creation of finishing coatings for waterproof
ers in waterproof leathers on the one hand and leathers is a complex task. Technologists on leather to increased requirements for industrial safety and manufacture and finishing should develop production
Hydrophobization of shoe upper leather on the basis of new polymer composites...
technology in close cooperation and carefully select materials for liquid and finishing processes [1-3; 8]. Thanks to the fibrous structure leather and leather goods easily absorb moisture. Wet leather looses its heat-protective properties and water vapor permeability; it easily rots and gets moldy. After drying leather becomes hard, brittle, and its flexing life decreases.
To obtain the desired technological effect from two or more water soluble polymers, besides correct selection of components, it is very important to know their initial ratios in composites, which drastically affect the properties of treated materials for leather goods.
In order to achieve the indicated purpose it was necessary to develop new polymer based hydropho-biziting compositions, investigate rheological properties of their solutions and determine the kinetics of absorption of moisture by leather.
Therefore, the aim of our work was to study the properties of composites based on acrylic polymers and polyvinilethynildihidroxichlorsilan as a hydro-phobizing finishing materials.
Hydrophobizators were prepared by consistent mixing of initial materials at different ratios (mass%) for test variants: acrylic emulsion — 20% 40-70, polyvinilethynildihidroxichlorsilan — 80% 2-12, industrial oil IA-20-12-53, penetrator — 4-6, for a control variant: polyethylhydrosiloxane (GKZH-94) — 100, at a temperature of 20-22 °C for 3-4 h.
As is known, the formation of new high-molecular compounds or transition of organic compounds (monomers) into polymer leads to shock changes in their initial conformational state, molecular weight and viscosity.
As expected, with rise in temperature hydrophobizator solution viscosity decreases. The research of influence of mass% of polyvinilethynil-dihidroxichlorsilan in a mix with synthetic polymers on viscosity of systems determined that all results obtained with rise in temperature have smooth reduction in viscosity.
The maximum viscosity value for the compositions investigated by us corresponds to 70 mass% of acrylic emulsion, 12 mass% of polyvinilethynil-dihidroxichlorsilan, 12 mass% of industrial oil, and 6 mass% of penetrator. The increase in mix viscosity
speaks that a significant amount of halogenous and hydroxyl groups containing in macromolecules of polyvinilethynildihidroxichlorsilan promotes occurrence between separate components of rather strong intermolecular bonds, in which an aggregation process with formation of composite compounds can take place.
It should be noted that in all cases the viscosity of the control sample with traditionally used polyethylhydrosiloxane is 10-50 standard units lower as compared with that of the test samples. This indicates the interaction of initial components as well as their additional plasticization.
To study the kinetics of moisture absorption by shoe upper leather groups of 16 samples, 150 x 25 mm, composed by the asymmetrical fringe method were wetted in aqueous medium. It should be pointed out that the leather samples were treated in advance with hydrophobizing compositions obtained.
The leather samples of the control groups were wetted in pure water at a temperature of 20.0 ± 2.0 °C. The absolute humidity of all samples was measured over 10, 20, 30, 40 and 50 min of wetting.
Figure 1 provides kinetics of moisture absorption by shoe upper leather.
As is clear from Figure 1, with rise in wetting time the rate of moisture absorption by leather increases. However, rise in time over 40 min slightly influences on speed of moisture absorption by leather. It is due to different wetting ability of hydrophobiziting composition.
In connection with the above mentioned, our researches compared rates of moisture absorption by shoe upper leathers treated with the control and test hydrophobizing compositions under their watering at a temperature of 40 °C.
On the basis of the data obtained (Fig. 2) and identified kinetics, it is expedient to use high temperature at wetting shoe upper leather other than normal temperature.
The researches determined that the maximum increase in rate of shoe upper leather wetting takes place at a temperature of 30-35 °C.
In view of the fact that shoe upper leather is often used in wet conditions, it was interesting to study
the influence of hydrophobizators obtained on water tion were wetted and dried cyclically. Wetting took
resistance of shoe upper leather under cyclic wet- place in water at a temperature of 30 °C for 35 min,
tings and dryings. Leather samples wetted accord- and drying — in natural conditions within 48 h. The
ing to different variants and dried to air-dry condi- data obtained are given in Figure 3.
p 50
__i--
V
____ 1- IV
___ II
- r r- 1
40 50
Time, min
Fig.2. Kinetics of moisture absorption by shoe upper leather depending on wetting time: I-IV — test and V — control hydrophobizator components
Temperature, °C
Fig. 3. Kinetics of moisture absorption by shoe upper leather depending on wetting temperature: I-IV — test and V — control hydrophobizator components. 30min
Fig. 4. Influence of hydrophobizator composition on moisture sorption by shoe upper leather under cyclic watering: I-IV — test and V — control hydrophobizator components
The results obtained indicate that previously watered samples retain moisture absorption indexes in 6-10 wetting cycles. It can be also seen that in all wetting cycles the absolute humidity of the test variants, especially IV, is 1.5-2.0 times lower than that of the control variant.
Thus, the researches determined that polymer composites with polyvinilethynildihidroxichlor-silan increase waterproof properties of shoe upper leather by 1-2 times compared to those with poly-ethylhydrosiloxane.
The experiments also show that the samples previously wetted with the control hydrophobizator have lager moisture absorption index value. However, after 6-10 cycles the value of pre-watered leather samples stabilized gradually. This is obviously due to the fact that water in the further processes in contact with the leather forms rather strong bonds with the dermis structural elements. Therefore, shoe upper
leather absorptivity rises and as a result water resistance of footwear increases.
Conclusions: It was firstly established the possibility to apply a new hydrophobizing composition based on polyvinilethynildihidroxichlorsilan and acrylate during leather goods finishing, which allows increasing conformation transformation of finished goods and regulating subprimary structures of natural leather surface grain, and leads to increase of physical mechanical properties and improvement in the quality of production.
Reduction of adsorptive capacity of hydropho-bized leathers treated with new hydrophobiziting compositions is based on additional action and character of deposition of globules in the leather microstructure. Due to specific composition applied on leather surface grain, growth in number of fine pores occurs, which promotes increasing moisture condensation rate in them.
References:
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Research the catalytic activity of the complexes in olefin acrylonitrile Oxidation reactions
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Gurbanova Rena Vagif Hajiyeva Reykhan Shamardan, Azerbaijan State Oil and Industry University Avenue: 20Azadlig, Baku AZ1010. Azerbaijan E-mail: [email protected]
Research the catalytic activity of the complexes in olefin acrylonitrile Oxidation reactions
Abstract: There has been studied for the first time the process of transition metal and metals salts chlorides to the polymerizing mixture have been shown to effect markedly on the properties of the forming immobilized polymers.
Keywords: Acrylonitrile complex compounds, homogeneous catalytic, Transition, metals, immobilized polymers.
Introduction The understanding of the fundamental processes
The development of new highly efficient ho- determining the formation of active centers in cata-mogeneous catalytic systems on the basis of metal lysts in the course of their preparation as well as dur-complex compounds and their use in the synthesis ing their interaction with reaction medium is neces-processes of polymeric materials for different pur- sary for catalysis theory and creation of new highly poses are of significant interest for catalysis. efficient catalysts for commercial realization [1].
