Preparation and Formulation of Low-toxic Neoprene Adhesive

[Abstract]: In 2002, the Standardization Committee made the following requirements for solvent-based adhesives: benzene content ≤ 5 ‰, toluene, xylene content ≤ 20%, solvent evaporation total ≤ 750 g/l. This work focuses on finding mixed solvents that meet the above requirements, and recommends an adhesive formulation that is more economical and has stronger adhesion.

[Key words]: mixed solvent, initial tack, adhesiveness

This year, the Institute of Shanxi Synthetic Rubber Group Co., Ltd. conducted research on low-toxic neoprene adhesives in accordance with the company's arrangements. The main reason is to find a suitable low cost toxic solvent mixture ratio. Among them, only acetone is slightly more expensive than the current commonly used solvents, and the amount is not large. As a result, the cost of the adhesive is increased by about 150 yuan per ton. The neoprene adhesive formulated with this mixed solvent has a high initial tack, and can maintain a long sticking time, and has good brushing and sticking properties.

1. Formula:

1.1 Mixed solvent ratio:

Toluene 0.24 is commercially available

Acetone 0.19 is commercially available

6 # solvent oil (or 120 # gasoline) 0.57 commercially available

1.2 Adhesive Formula:

1.2.1 Resin Liquid Formula:

2402 resin 0.294 available

Mixed solvent 0.667 is commercially available

Active magnesium oxide 0.029 is commercially available

Distilled water 0.010 homemade

1.2.2 Adhesive Formula:

CR244 0.151 Shanxi Synthetic Rubber Group Co., Ltd.

1

Mixed solvent 0.704

Resin liquid 0.144

Antioxidants 264 0.001

2. Adhesive production process:

2.1 Preparation of resin solution:

According to the ratio, the mixed solvent is added to the kettle, 2402 resin, activated magnesium oxide and water are successively put into the kettle, and the hydrazine reaction at room temperature is not less than 8 hours, and the prepared resin liquid is used.

2.2 Making Adhesives:

2.2.1 plastic CR244, resulting in a smooth and shiny plastic surface. A small amount of magnesium oxide can also be mixed during the process to prevent scorching of the glue.

2.2.2 Put the mixed solvent into the kettle, turn on the stirrer, place the CR244 piece that has been plastically refined, stir it at room temperature until the glue is completely dissolved, and then add the resin liquid. This process takes no less than 12 hours.

3. Performance test:

3.1 Sticky canvas test, see data in the attached table:

X1234a564b 25°C rotational viscosity (mPa.s) 4301050137587558011251075 initial tack strength (N/cm) 4.678.0011.348.677.343.332.024 hour end tack strength (N/cm) 42.6945.6950.0320.6951.3651.3646.66

In the attached table, 4a and 4b are the same glue, 4a is a low-toxicity formula, and 4b is the currently used formula (non-environmental). And the same solid content. It can be seen that the low-toxicity formula has a strong initial tack and better brushing properties (lower revolving sticks and lower levels).

3.2 Sticky Tri-plate Test:

Like most viscous tri-layer boards used in adhesive factories, adhesives made with this formula can be laminated 7 minutes and 50 minutes after the glue is applied, and the adhesive strength is high.

4. Economic Analysis:

According to the neoprene adhesive produced by this formula, the acetone content is about 15%, resulting in an increase in the cost of adhesives of less than RMB 150/ton (the price of acetone seen in newspapers is RMB 1,000/ton higher than that of toluene). It is acceptable to most adhesive manufacturers.

5. Results and discussion:

5.1 The low toxicity neoprene adhesive made of toluene, acetone and 6# solvent oil not only meets the requirements of the new standard, but also has a reasonable price.

5.2 The adhesive produced by this formula has high initial tack, long sticking time and strong final tack.

5.3 Adhesive manufacturers can produce according to the above formula, but the adhesive preparation time should be 20 hours.

5.4 Discussion

5.4.1 "Triphenyl" is a good solvent for chloroprene rubber. Although many people of insight have done a lot of work in recent years, the purpose is to replace "triphenyl" with a mixed solvent. However, due to the lack of a clear standard to limit, some adhesive manufacturers are driven by profit-driven and technical levels, producing binders with a high content of "triphenylene", and even some manufacturers using pure benzene as the main solvent. , causing great harm to the environment and human health. The promulgation of the new standard clarified the content of “triphenyl” in adhesives and promoted the production of neoprene adhesives with low-toxicity mixed solvents. The recommended mixed solvent, despite the slight increase in cost per ton of adhesive, it The toxicity has been greatly reduced compared with before, especially the large amount of solvent oil (more than 50%), because its allowable concentration in the air is 0.3mg/L, which greatly improved the operating environment to ensure the health of construction workers. Acetone is used to adjust the solubility parameter and the hydrogen bond index of the mixed solvent. The amount can be adjusted between 15% and 20%. If the temperature of the adhesive is high, butanone can be used instead of acetone, but the price is slightly increased.

5.4.2 The neoprene adhesive made of mixed solvents has a slightly lower rotational viscosity, which is beneficial to the application of glue. The manufacturer does not need to worry about this, and the adhesive strength should be used to measure the quality of the formulation.

5.4.3 The neoprene adhesive made from the mixed solvent is inferior to the toluene solvent in low temperature resistance, but can be improved by appropriately increasing the acetone or butanone content. Acetone (or methyl ethyl ketone) accounts for up to 30% of the mixed solvent. It can also be improved by replacing some of the solvent oil with methylene chloride.

Source: Chemical Fine Network