Method for rapidly cold-sealing corrugated cartons with corn starch adhesive 1

(I) Raw materials and recipes

Corn Starch 12.5% ​​NaCLO Solution 8.9%
30% NaOH solution 10%
Water 67.7%
Sodium thiosulfate 0.3%
Drier (homemade) Appropriate borax 0.4%
Catalyst (NiSo4) Tributyl phosphate 0.2%

(B) Preparation of Adhesives

First, in a reactor equipped with an electric stirrer, put in a good amount of corn starch. Add a suitable amount of water and stir it to make it fully wet. Adjust the pH to be alkaline. Under constant stirring, add the catalyst and NaCLO solution, stir for 40 minutes, and measure the fluidity (by inserting a 4 mm diameter round bar into the middle of the deep liquid, and then provoke it, you can see that the glue droplet breaks 2-3 cm long) Add appropriate amount of water, add borax and reducing agent, add antifoaming agent and driers after mixing evenly to obtain finished product.

(III) Performance Indicators of Products

Item Indicator Appearance Light Yellow Sticky Liquid Viscosity 25-35
PH 8-10
After the initial sticking time 6-10min adhesive material damage drying time (h) 2-3
Peel strength (N/m楞) ≥588
Storage period (month) 4

(d) Discussion

4.1 Selection and dosage of oxidants

The choice and amount of oxidizing agent is the key to making the adhesive. For a certain starch, the degree of oxidation is different and the resulting product has different properties. Commonly used oxidants are H2O2, Na2O2, NaCLO, KMnO4 and so on. Due to the deep coloration of the binder made with KMnO4, the cost of H2O2 and Na2O2 is higher, the degree of oxidation is not easy to control, and the melon time is long. In the experiment, NaCLO was decided. If the amount of oxidizing agent is too large, the starch may be degraded too much, the viscosity is too large, the fluidity is poor, and the storage stability is poor. After repeated experiments and comparisons, it was found that at room temperature alkaline conditions, the amount of NaCLO is preferably 7-10%.

4.2 Effect of Catalyst

Although NaCLO naturally decomposes atomic state (O) at room temperature, it proceeds slowly at room temperature. If a catalyst is added to reduce the activation energy of the reaction, the decomposition of the oxidant is accelerated, and the oxidation reaction time can be shortened. (to be continued)