Study on Triphenyl Solvent-based Neoprene Spray (I)

Foreword

The currently available commercial triphenyl-containing neoprene spray adhesive has excellent properties such as low viscosity, good mechanical sprayability, high initial tack, high bond strength, and high heat resistance, etc., and is widely used in construction and automobiles. , furniture, furniture and other industries, the country's annual sales of more than 20,000 tons. However, due to the fact that the content of triphenyl solvent in neoprene spray adhesive accounts for about 30%, that is, about 6,000 tons of triphenyl solvent is emitted to the air at each construction site every year, which seriously pollutes construction workers and users to a certain extent. Living environment.

In this paper, a low-toxic mixed solvent was used instead of triphenyl solvent to prepare triphenyl-free neoprene spray adhesive. The viscosity, viscosity retention time and initial tackiness of neoprene spray adhesive were studied by mixed solvent, neoprene and tackifying resin. The impact of bond strength, and the successful development of industrial spray.

1 Experimental section

1.1 Raw materials

Neoprene, E-brand, A-30, A-90, M-40, M-100, Japan Electrochemical Industry Corporation. Tert-butyl phenolic resin, FRJ-551, softening point 110°C, American Schenectady Chemical Company: terpene phenolic resin, T803, softening point 145°C, Xiamen Arakawa Chemical Company: Terpene resin, T-100, softening point 100°C, Fujian Qingliu Perfume Factory; Rosin Modified Phenolic Resin, 210, Softening Point 130°C, Shanghai Haida Chemical Plant: Rosin Glyceride, GER-85, Softening Point 85°C, Guangxi Wuzhou Richeng Chemical Chemical Company: Coumarone Resin , special grade, softening point 85 °C, Shanghai Coking Plant. Active magnesium oxide, STARMAG-150, Konoshima Chemical Co., Japan; Active zinc oxide, Shanghai Jinghua Chemical Plant. Antioxidants, Irgarnox-1010, German Ciba. Catalyst, self-made. Toluene, Cyclohexane, Hexane, Methyl Ethyl Ketone, Acetone, Solvent Gasoline, Chemical Pure, Shanghai Light Chemical Company

1.2 Experimental Procedure

In a 1000 ml four-necked flask equipped with a dropping funnel, a reflux condenser, a thermometer, and a stirrer, non-polar solvents such as 50 g of t-butyl phenolic resin, 5 g of activated magnesium oxide, 1 g of the catalyst, and a mixed solvent of a certain amount were added (e.g. Toluene, cyclohexane, n-hexane, solvent gasoline, stirring at room temperature for 12 to 16 hours, and adding the remaining polar solvents (such as methyl ethyl ketone and acetone) in the mixed solvent until the end of the reaction, until the total amount of mixed solvent required 500g. Then, 100 parts of chloroprene rubber (such as A-30, A-90, M-40, and M-100), 4 parts of active magnesium oxide, 4 parts of active zinc oxide, and 1010 parts of antioxidants are kneaded on a mixer. And cooling, shredding, take its broken film 110g added to the above pre-reaction flask, stirring continued at room temperature dissolved 8 ~ 12h, to obtain a certain viscosity and solid content neoprene spray.

1.3 Test performance

1.3.1 Determination of Viscosity and Solids Content

The viscosity of the neoprene spray (mPas/25° C.) was determined according to GB 2794-1995 using a LVF type viscometer from Brookfriel. According to the provisions of GB2793-1995, the solid content (%) of neoprene spray adhesive was measured with a ZA2003 electronic balance of Shanghai Tianping Instrument Factory.

1.3.2 Determination of sticky retention time On a canvas strip of 25 mm wide by 20 mm long, spray evenly with neoprene spray and repeat two times. After 10 minutes of natural drying at room temperature, start the timer and test the two adhesive surfaces every 5 minutes. Overlap each other, rolling with a hand roll strong, and then hand on both sides of the canvas along both sides of 180 ° tear, until it is not easy to tear open, this time is the sticky time.

1.3.3 Determination of Adhesive Strength

On a 25-mm-wide by 200-mm-long canvas strip, neoprene spray was sprayed with a Narita F75 spray gun and the spraying was repeated twice. After naturally drying at room temperature for 10 min to 15 min, the two adhesive surfaces of the sample strips are superimposed on each other, rolled by a hand roller, and glued into canvas samples. According to the provisions of GB/T532-1997, the bonding strength (kN/m) of the canvas/canvas test strips after 5 minutes and 24 hours at room temperature was measured using a XL-50A tensile testing machine of Guangzhou Experimental Instrument Factory.

2 Results and Discussion

2.1 Influence of Mixed Solvents

Take the neoprene A-30 grade, change the volume ratio of various mixed solvents (1/1/1 or 1/3/3), according to the above experimental procedure to obtain a neoprene spray with a solid content of 25%, measure the viscosity and The sticky holding time was observed and the spraying effect was observed. The results are shown in Table 1.

From Table 1, it can be seen that in the three mixed solvent systems of neoprene spray adhesive, regardless of the volume ratio is 1/1/1 or 1/3/3, the dissolution parameters (δ) and hydrogen bond index (γ) The sum of both) is in the range of 12.7±1.0, which is close to the sum of the neoprene's solubility parameter (δ=9.2 or 9.5) and the hydrogen bond index (γ=3.5) (δ+γ=12.7 or 13.0)[4], or It is in the range of 11.0 to 15.3 (δ+γ=7.5 to 9.8±3.5 to 5.5) [5], which completely dissolves the neoprene rubber. When the volume ratio of toluene/acetone/n-hexane mixed solvent is 1/1/1 or 1/3/3, the neoprene spray viscosity is slightly higher, the viscosity is maintained for a long time, and the sprayability is good.

When the volume ratio of cyclohexane/acetone/gasoline mixed solvent is 1/1/1 or 1/3/3, the neoprene spray viscosity is relatively moderate, the viscosity retention time can reach the general construction requirements, and the sprayability is good. When the volume ratio of methyl ethyl ketone/acetone/n-hexane mixed solvent is 1/1/1 or 1/3/3, the neoprene adhesive has low viscosity and is most suitable for mechanical spraying and can be sprayed in the air instead of being sprayed. Spider-like mesh, greatly improving the spraying effect, the sticky holding time of 20 minutes is convenient for construction, and the sticking period of 10 minutes is too short to make construction inconvenient. Therefore, the use of methyl ethyl ketone/acetone/n-hexane (1/1/1) as a mixed solvent system without triphenyl solvent neoprene spray has a good spraying effect.