CN1243854A - Process for preparing adhesive of urea-formaldehyde resin - Google Patents

Abstract

A process for preparing a binder of urea-formaldehyde resin features that the mole ratio of urea to formaldehyde is controlled to 1 : (1.2-2.0); and the aqueous solution of sodium hydroxide, triethanolamine and hexamethinetetraamine is used as catalyst; the urea is added by several times by the fine-flowing dropping for the first time and the reaction takes place in weak acidity condition. Its advantages are high reaction speed, high binding characteristic and stability and better appearance of resultant resin, and excellent antiblocking performance.

Description

A kind of Preparation of urea-formaldehyde resin adhesive method

The present invention relates to a kind of preparation method of aminoresin tackiness agent.

Urea formaldehyde resin adhesive is with low cost because of its raw material is easy to get at present, already is extensive use of at the bamboo lumber yard, has also obtained application simultaneously in granulated meal processing.The urea-formaldehyde resin adhesive production technique comprises the urea of certain mol proportion and formaldehyde under catalyst action, carries out addition reaction and polycondensation.The addition reaction of urea and formaldehyde is carried out under weak basic condition usually, and the polycondensation of urea and formaldehyde is carried out under solutions of weak acidity usually, discloses this technology as Chinese patent CN1038100C.But adopt this technology, speed of response is slow, and the bond properties of resin, outward appearance and stability can not be satisfactory.

The object of the present invention is to provide a kind of degree of adhesion height, have the Preparation of urea-formaldehyde resin adhesive method of good appearance and stable performance.

For achieving the above object, the present invention by the following technical solutions: the mol ratio of urea and formaldehyde is controlled at 1: between the 1.2-2.0, these two kinds of raw materials are in and carry out addition and polycondensation under the solutions of weak acidity, and comprise the steps:

A), formalin is added in the reactor, start stirring, and the adding basic catalyst is regulated pH value=5.5-7.0, described basic catalyst is the aqueous solution of sodium hydroxide, trolamine, hexamethylenetetramine, its weight proportion is a sodium hydroxide: three ethanol: six methynes, four ammonia: water=1-3: 0.5-20: 0.2-10: 100-200, and be warming up to 65-85 ℃;

B), the logical steam of the 55-85% of required urea total amount is melted, temperature is controlled at 75-85 ℃, and thread splashes into reactor in 20-40 minute;

C), drip urea after, between 90-100 ℃ insulation reaction 30-60 minute;

D), the usefulness 5-10% ammonia chloride aqueous solution is regulated pH value=4-5.5, and is added the surplus urea reaction to terminal;

E), with the pH value=6.5-7.5 of 10-15% aqueous sodium hydroxide solution conditioned reaction liquid, termination reaction;

F), use the chuck water quench to 30-45 ℃ of discharging barrelling reactor.

The present invention also can adopt following further technical scheme: add the polysiloxane surfactant of 0.1-1.0% at the reactant of discharging, carry out spraying drying then.

In general, being reflected under the solutions of weak acidity of urea and formaldehyde carried out, speed of response is very fast, Resin adhesive bond strength height, the outward appearance that generates and having good stability, though thermal discharge is big in its reaction process, in the production as control improper easy generation gelatin phenomenon, but owing to adopted technique scheme, splash into reactor after particularly the logical steam of urea being melted, and the selection by temperature of reaction, time, pH value, make that the speed of response of urea and formaldehyde is controlled effectively, broken through the forbidden zone that urea-formaldehyde resin in the past prepares under solutions of weak acidity; Can make the urea-formaldehyde resin prevented from caking owing in the reactant of discharging, add polysiloxane surfactant simultaneously, be in Powdered uniformly, easy to use.

The invention will be further described below in conjunction with embodiment.

Embodiment 1:

The mol ratio of urea and formaldehyde is 1: 1.6, and its reaction process step is as follows:

A), 37% formalin with 350kg adds in the reactor, and the adding basic catalyst is regulated pH value=6.5 under constantly stirring, described basic catalyst is the aqueous solution of sodium hydroxide, trolamine, hexamethylenetetramine, its weight proportion is a sodium hydroxide: trolamine: hexamethylenetetramine: water=1.2: 0.9: 0.7: 120, and be warming up to 68 ℃

B), with required urea total amount 78% promptly the logical steam of 125 kg melt, temperature is controlled at 80 ℃, and thread splashes into reactor in 25 minutes,

C), drip urea after, 92 ℃ of insulation reaction 35 minutes,

D), with 10% ammonia chloride aqueous solution conditioned reaction liquid pH value=4.8, and add remaining 35kg urea reaction to 20 ℃ of cloud points,

E), with pH value=7.0 of 15% aqueous sodium hydroxide solution conditioned reaction liquid, termination reaction,

F), with logical chuck cooling water temperature to the 35 ℃ discharging of reactor.

G), add the polysiloxane surfactant that accounts for reactant weight 0.25%, carry out spraying drying then and make powdery product at the reactant of discharging.

Embodiment 2:

The mol ratio of urea and formaldehyde is 1: 1.25, and its reaction process step is as follows:

A), 37% formalin with 380kg adds in the reactor, and the adding basic catalyst is regulated pH value=6.0 under constantly stirring, described basic catalyst is the aqueous solution of sodium hydroxide, trolamine, hexamethylenetetramine, its weight proportion is a sodium hydroxide: trolamine: hexamethylenetetramine: water=1.8: 2.1: 1.5: 150, and be warming up to 75 ℃

B), be that the logical steam of 160kg melts with 70% of required urea total amount, temperature is controlled at 80 ℃, and thread splashes into reactor in 35 minutes,

C), drip urea after, 95 ℃ of insulation reaction 52 minutes,

D), with 10% ammonia chloride aqueous solution conditioned reaction liquid pH value=5.3, and add remaining 70kg urea reaction to 20 ℃ of cloud points,

E), with pH value=7.0 of 15% aqueous sodium hydroxide solution conditioned reaction liquid, termination reaction,

F), with logical chuck cooling water temperature to the 30 ℃ discharging of reactor.

G), add the polysiloxane surfactant that accounts for reactant weight 0.55%, carry out spraying drying then and make powdery product at the reactant of discharging.

Embodiment 3:

The mol ratio of urea and formaldehyde is 1: 1.85, and its reaction process step is as follows:

A), 37% formalin with 420kg adds in the reactor, and the adding basic catalyst is regulated pH value=5.8 under constantly stirring, described basic catalyst is the aqueous solution of sodium hydroxide, trolamine, hexamethylenetetramine, its weight proportion is a sodium hydroxide: trolamine: hexamethylenetetramine: water=2.5: 6.0: 3.5: 180, and be warming up to 68 ℃

B), be that the logical steam of 111kg melts with 65% of required urea total amount, temperature is controlled at 82 ℃, and thread splashes into reactor in 28 minutes,

C), drip urea after, 98 ℃ of insulation reaction 45 minutes,

D), with 10% ammonia chloride aqueous solution conditioned reaction liquid pH value=4.5, and add remaining 60kg urea reaction to 20 ℃ of cloud points,

E), with pH value=7.0 of 15% aqueous sodium hydroxide solution conditioned reaction liquid, termination reaction,

F), with logical chuck cooling water temperature to the 30 ℃ discharging of reactor.

G), add the polysiloxane surfactant that accounts for reactant weight 0.85%, carry out spraying drying again and make powdery product at the reactant of discharging.

Claims (2)

1, a kind of Preparation of urea-formaldehyde resin adhesive method, the mol ratio of urea and formaldehyde is controlled at 1: between the 1.2-2.0, it is characterized in that these two kinds of raw materials are under the solutions of weak acidity reacts, and comprises the steps:

A), formalin is added in the reactor, start stirring, and the adding basic catalyst is regulated pH value=5.5-7.0, described basic catalyst is the aqueous solution of sodium hydroxide, trolamine, hexamethylenetetramine, its weight proportion is a sodium hydroxide: trolamine: six methynes, four ammonia: water=1-3: 0.5-20: 0.2-10: 100-200, and be warming up to 65-85 ℃;

B), the logical steam of the 55-85% of required urea total amount is melted, temperature is controlled at 75-85 ℃, and thread splashes into reactor in 20-40 minute;

C), drip urea after, between 90-100 ℃ insulation reaction 30-60 minute;

D), the usefulness 5-10% ammonia chloride aqueous solution is regulated pH value=4-5.5, and is added the surplus urea reaction to terminal;

E), with the pH value=6.5-7.5 of 10-15% aqueous sodium hydroxide solution conditioned reaction liquid, termination reaction;

F), reactor is led to the chuck cooling water temperature to 30-45 ℃ of discharging barrelling.

2, a kind of Preparation of urea-formaldehyde resin adhesive method as claimed in claim 1 is characterized in that the polysiloxane surfactant at the reactant adding 0.1-1.0% of discharging, then spraying drying.