Effect of Raw Materials on the Performance of One-component Polyurethane Adhesive for Plastic Tracks

Abstract: The effects of various components on the properties of one-component Polyurethane adhesive for Plastic Track were studied. Comprehensive analysis shows that when the relative molecular mass of Polyether polyol N-340G is between 4000 and 5000, and the use amount of specialty additive E is around 10%, the mechanical properties and cost-effectiveness of the synthesized adhesive are the best; aging test results show that the Under the conditions, the samples prepared with Adhesive 6 still have higher mechanical properties than other adhesives after aging.

Polyurethane (PU) plastic track materials have excellent anti-slip, flame-retardant, shock-absorbing properties, anti-static properties, beautiful colors and other characteristics, first developed and applied in foreign countries, China began to develop PU materials for sports venues in 1972, after years of development Currently, there are PU plastic runway material products such as hybrid plastic runways, all-PU course flooring (including silicon PU, etc.) and indoor plastic floor materials [2], but these varieties are still far from meeting the market's needs. The future development trend of Paving materials for plastic runways will be reflected in the following aspects: (1) Development of new products, such as surface embossed pre-formed particle-free plastic runways and field-cast embossed particle-free plastic runways. (2) Product cost-effective competition, such as low-cost breathable runways, cost-effective hybrid plastic runways, and full-PU floor materials. Breathable track products are mainly reflected in the competition of runway adhesive products. (3) Development of environmentally friendly pavement materials.

The breathable plastic runway is mainly composed of a bottom surface adhesive, a middle layer of 9 mm black particle layer, and a surface layer of 3 mm non-slip coating layer. It has air permeability, water permeability, high elasticity, low cost, and the appearance can be sprayed in various colors, etc. Loved by users. However, there are few reports on the study of the one-component polyurethane adhesives bonded to the black particles in the intermediate layer in the country. Therefore, the present work aims at the study of one-component polyurethane adhesives for low-cost breathable plastic runway interlayers. The influence of each component on its performance was discussed, which provided a reference for the development of this adhesive.

1 Experimental section

1. 1 The main raw material

Polyether polyols: N-220 (hydroxyl number 54.5 to 57.5 mgKOH/g, Mn=2000), N-330 (hydroxyl number 54.5 to 57.5 mgKOH/g, Mn=3000), N-340G (hydroxyl value 31 to 35 mg KOH /g, Mn=4000～5000), Industrial Grade, Jiangsu Zhongshan Chemical Co., Ltd.; Isocyanate (MI-50, TDI), Industrial Grade, Shanghai BASF Polyurethane Co., Ltd.; Special Additive E (Ester Plasticizer), Industrial grade, Wenzhou Dacheng Chemical Co., Ltd.; chlorinated paraffin, industrial grade, Anhui Xingxin Chemical Technology Co., Ltd.; one-component Polyurethane Adhesive (MDI type), Shandong market hot products; PU rubber particles (particle size 3 ~ 4mm) ,self made.

1. 2 Major Equipment and Instruments

Universal Tensile Machine, Model XD-121, Shanghai Trust Instrument Co., Ltd.; Rotary Viscometer, Model NDJ-1, Shanghai Sidelis Precision Instrument Co., Ltd.

1. 3 Runway Sample Preparation and Process

Weigh a certain amount of polyether according to the formula, add three-necked flask, and then weigh a certain amount of isocyanate according to the theoretical calculation, add the flask to it, heat it to 80～90°C for constant temperature for 2 hours, cool to 50°C, add a certain amount of Chlorinated paraffin and special additives E, out of materials, to get one-component polyurethane adhesive (NCO mass fraction 6% ~ 7%).

250 g of self-made adhesive and 1750 g of PU rubber granules were weighed and mixed uniformly at a mass ratio of 1:7, paved on 30 cm × 50 cm steel molds and compacted to prepare 30 cm × 50 cm × 0.9 cm The air-permeable runway samples, placed for 1 to 2 weeks, were made into test samples and mechanical properties and aging resistance were tested in accordance with national standard GB/T14833-2011.

2 Results and Discussion

2.1 Effect of Polyether Polyols on Adhesive Properties

Adhesive 1 and adhesive 2 were prepared with N-330 or N-340G and N-220 (mass ratio of 2:1) according to the above section 1. 3 process. The amount of chlorinated paraffin and special agent E in adhesive 2 was 10%. %, The single-component rubber adhesive 3 sold by Shandong market is selected as a reference. The mechanical performance test results are shown in Table 1.

It can be seen from Table 1 that the runway sample prepared with Adhesive 2 is more than twice as high as the elongation at break of the runway sample prepared with Adhesive 1, and the tensile strength is 50% higher. At the same time, it is also higher than that of the single-component adhesive 3 sample. Because the adhesive 1 raw material polyether polyol is N-330, its relative molecular weight is 3000, and the adhesive 2 raw material polyether polyol is N-340G. The relative molecular mass is 4000 to 5000, a difference of 1000 to 2000. It shows that the greater the relative molecular mass of the polyether, the better the elongation properties of the adhesive and the higher the tensile strength.

Under the same conditions, the adhesive 1, adhesive 2 and PU rubber particles were made according to 1:7, 1:8, 1:10, 1:12. The test performance is shown in Table 2.

It can be seen from Table 2 that due to the relatively large molecular weight of the adhesive 2 polyether component, under the same conditions that increase the mixing ratio of the adhesive and the rubber particles, the decrease in mechanical properties is smaller than that of the adhesive 1, and the mixing ratio is increased to 1 : At 12 o'clock, the requirements of the testing standards can still be met. Adhesive 1 can no longer meet the testing standards when the mixing ratio is increased to 1:8. It can be seen that the increase in the relative molecular mass of the polyether can increase the mixing ratio of the racetrack particles and the adhesive, thereby saving the use of construction adhesives and reducing the cost of raw materials.

2. Effect of 2 Additives on Adhesive Properties

Fixed polyether N-340G and N-220 mass ratio of 2:1. Add 10% chlorinated paraffin into the polymerized adhesive and add 0%, 5%, 10%, 15%, 20% respectively. The special additive E, prepared adhesive Nos. 4, 5, 6, 7, 8 and adhesive 9, prepared without chlorinated paraffin wax and special additive E, was then used to make a runway sample, and its mechanical properties and curing stability were tested. Time, comparison results are shown in Table 3 and Table 4.

From Table 3, it can be seen that when the amount of chlorinated paraffin and special agent E in adhesive 6 is 10%, the mechanical properties of the sample are the best. Adhesives 4,5,6,7, the total amount of auxiliaries ≤25%, the mechanical properties are higher than the adhesive without auxiliaries 9; However, the mechanical properties of the adhesive 7 have dropped significantly, and the performance of the adhesive 8 is lower than that without additives Adhesive 9 performance, indicating that the plasticizer cannot be used too high. Plasticizers are well-suited to improve the performance of the adhesive. Excessively high plasticizers reduce the performance of the adhesive.

From Table 4, it can be seen that chlorinated paraffin and special additives E have a delaying effect on the curing and stabilization of the adhesive. When no additives are added, such as Adhesive 9, the curing performance is stable for 1 week and 2 weeks, indicating that the mechanical strength can be achieved within 1 week; while Adhesives 4, 6, and 8 are at 2 weeks and 2 respectively. Only when the week and 3 weeks have reached the required mechanical strength. This may be due to the fact that chlorinated paraffin is a plasticizer and has a strong plasticizing capacity, which results in slower phase separation of polyurethane molecular chains and delayed mechanical properties. The increase in the use of specialty auxiliaries E, which interacts with chlorinated paraffins, is even more pronounced. It takes 3 weeks for Adhesive 8 to reach its intended mechanical strength. Although the additives can reduce the cost, but from the perspective of stable curing and aging resistance, the amount of chlorinated paraffin and special additives E should not be used, otherwise it will affect the adhesive aging resistance.

Considering comprehensively, the curing time and mechanical properties of the adhesive 6 reach the optimum value and the cost is also low.

2. 3 Effect of Isocyanate on Adhesive Properties

TDI and MI-50 (MDI) were selected to make adhesives with polyether N-340G, N-220 (N-340G to N-220 mass ratio 2:1), and auxiliaries were selected for 10% of chlorinated paraffin and 10% for Specialty additives E. See Table 5 for performance comparison.

It can be seen from Table 5 that TDI adhesives have relatively low viscosity and are convenient for construction. However, they have irritating toxicity and need to wear gas masks. Mechanical properties, elongation and tensile strength are lower than that of MDI type. The adhesive, which is due to the MDI structure is more regular than the TDI, is more conducive to the phase separation of the adhesive after curing. Comprehensive comparison, using MDI (MI-50) is more appropriate.

2. 4 Comparison of sample aging resistance

Plastic samples were prepared with adhesives 3, 6, and 9 and aging tests were performed according to GB/T14833-2011. The aging time was 168 h. Table 6 shows the comparison of mechanical properties before and after aging.

It can be seen from Table 6 that after aging, the mechanical properties of the adhesive 3 have the largest drop, and the tensile strength even fails to meet the standard requirements; however, the elongation and tensile strength of the adhesive 6 before and after aging are determined in this experiment. Respectively decreased by 10% and 13%, and still far exceeds the standard requirements; Without adhesive 9, the elongation at break and tensile strength decreased by 8% and 11%, respectively, before and after aging.

3 Conclusion

The relative molecular weight of polyethers and additives have a significant impact on the performance of single-component polyurethane adhesives for breathable plastic runways. When N-340G and N220 are mixed in a mass ratio of 2:1, the amounts of chlorinated phospholipids and specialty auxiliaries E are both At 10%, the single-component adhesives prepared for plastic runway samples have the best overall performance. The adhesive is currently authorized by the patent (Patent No. ZL200910263253. 7), and it has been industrialized and used, and the user has responded well.