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Shoe Modification of polyurethane adhesive

0 INTRODUCTION
synthetic polyurethane adhesives and polyurethane adhesives industry and new materials industries important product categories, are widely used in various areas of the national economy. It has the amine, isocyanate groups, carbonyl and metal, rubber, plastic surface of the groups have a strong chemical bonds, and stronger co-operation with the van der Waals force, it has a better performance than other adhesives. the last two years, the domestic polyurethane adhesive production scale and technological development rapidly, but these enterprises mainly in Germany, Spain, the United States and other imported resin dissolved, formula modified. the largest amount of shoes for more than 95% of polyurethane resin to rely on imports, the domestic several smaller independent development of devices, equipment, technology is relatively backward, product performance, still fail to Foreign standards; Experts predict that China will significantly increase the demand for polyurethane adhesive, to 1998, 103,000 tons as the base, with an average annual growth rate of about 10%; 2005 adhesive for shoes is about 183,000 tons. After years of exploration and study and found that the use of flexible synthetic polyhydroxy chains shoe adhesive, as compared with the same polyurethane adhesive with better adhesion.
1 Experimental part
1.1 main raw equipment materials
TDI (industrial grade) (Japan ) adipic acid (industrial grade) (Domestic) butanediol (industrial grade) (Japan)
glycol (industrial grade) (Domestic) diethylene glycol (industrial grade) (Domestic) maleic anhydride (industrial grade) (domestic)
1.2 Preparation of polyester polyol
the formula by adding the amount of binary alcohol and dicarboxylic acid with thermometer, stirrer, condenser of the four flasks, the temperature to 140 ℃, heat 1.5 ~ 2.5h separation reaction of water. heating to 200 ℃, at this temperature the reaction to the acid value is less than 10. cool ethyl acetate as solvent, dissolving out the material.
1.3 Preparation of polyisocyanate
the formula amount of TDI to join with dryer, blender, thermometer 3 flask, heated to 40 ℃, a gradual trickle-down polyol solution. about 2h drops finished, adding a catalyst Dibutyltin dilaurate, maintained at this temperature for 1.5h out pvc material, get 50% of the multi-isocyanate adhesive solution.
1.4 Performance Measurement
1.4.1 Adhesive
sample plate in 2mm thick mold, the coated with release agent, the vacuum deaeration and solvent had been removed more than the above-mentioned isocyanate adhesive casting mold in the flat, the room temperature for 48h, after stripping, and then placed on 7 days standby.
1.4.2 Tensile Properties of
will be a good film sample preparation, in the XL - 50A Electronic Tensile machine according to GB/T528-1998 "vulcanized rubber or thermoplastic rubber tensile stress-strain performance measurement" approach to testing the tensile strength and elongation at break.
1.4.3 Peel Strength
will be leather and rubber scissors into a 25mm wide-spline, using sandpaper polished hair, use a cotton ball dipped in acetone scrub addition to fat, to be volatile after the gluing of acetone, 3 ~ 4min after leather and rubber adhesive pressure, room temperature 24h; with tension test machine in order to (200 ± 10) mm / min loading rate of 180 ° means peel specimen, effectively stripping the length should be 70mm above, 10mm strip to the bonding part of the left until the calculation peel strength.
1.4.4 la shear strength:
with the PC board as a substrate a good sample preparation, in the XL-50A electronic pull machine refer to GB7124-86 "Determination of adhesive tensile shear strength" test tensile-shear strength.
2 results Discussion
polyester polyol and a diverse selection of polyol acid ratio, with multi-acid polyol choice, polyester polyols and TDI ratio experiment results are as follows:
2.1 Polyester Polyols effects on the adhesive properties of different
different polyester polyols of the adhesive properties of Table 1.
as diethylene glycol with ether, adipic acid long carbon chain of carbon atoms sp3 hybridized and therefore I from diethylene glycol with adipic acid polyester polyol prepared from a long chain of atoms are mostly free to rotate and therefore I have good flexibility. from the Table 1 known to use diethylene glycol with adipic acid and to a reasonable 1.20:1.00 ratio of income of the bonding agent for the best.
2.2 diols and diacids of different combinations and the relationship between the adhesive properties of binary acid and diols
ratio affects not only the poly - The molecular weight of polyol ester size, but also affects the main properties such as adhesive peel strength, tensile strength and so on. If the ratio of two low molecular weight may be too high, the viscosity is too large and the hydroxyl content is not directly cause adhesive containing-NCO reactive groups of the reduced impact of the use of the performance. excessively high molecular weight is too low, tensile and peel strength will decrease. diethylene glycol, and glycol ratio has influence on the adhesive properties are shown in table 2.
know that Diols from Table 2 with the ideal ratio of dibasic acid should be 1.2:1.0 2.3 polyester polyol and TDI of the OH / NCO ratio of
Since the adhesive is a reactive group -- NCO, in theory appear to be more of the group, combined with more points, naturally the greater the cohesive force. but that would require a significant increase in the amount of isocyanate, increase costs. At the same time no adhesive properties has risen markedly, but there is brittle became larger. based on the different OH / NCO ratio testing, the proceeds of bond performance index shown in Table 3.
know from Table 3, from the performance, cost factors into consideration to OH / NCO ratio 1.0:0.9 is appropriate.
2.4 of this product with a variety of performance polyurethane adhesive for shoes comparison
know from Table 4, this study applied the products as raw pvc materials such as diethylene glycol, and an appropriate ratio of the reactions, so its overall performance comparable with the imported products.
3 Conclusion
due to the production of ethylene glycol with diethylene glycol as a by-product of cheap, and its ether bond has good flexibility, in order to diethylene glycol instead of has been derived from the diol polyurethane adhesive, so that the cost of greatly reduced, due to a large number of amine, isocyanate groups, carbonyl, and rubber and leather has an excellent adhesive properties, its excellent flexibility, stretching and anti-stripping properties of non-Asian on certain imported products.
know from the above experiment, should choose diethylene glycol with adipic acid and to prepare for the ratio 1.2:1.0 shoe adhesive, polyester polyol. The polyester polyol thus obtained diisocyanate TDI with the ratio for OH / NCO = 1.0:0.9 for the better. Though the amount of increase in the performance of TDI has increased, but free of the TDI will be substantially increased, so that the damage caused by products increased substantially. and to 1.0:0.9 of the OH / NCO ratio, although the performance has not reached its highest point, but its very small quantities of free TDI, and TDI high prices, which will certainly lead to an increase in the amount of the cost has grown dramatically.
adhesive properties of this product tensile strength up to 56mPa, peel strength up to 5.6kN / m.

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