CN1291632A - Low-poison urea-formaldehyde resin adhesive and its preparing process - Google Patents

Abstract

A low-poison urea-formaldehyde resin adhesive is prepared from urea, formaldehyde, cyanuramide, phenolic resin and oxidized starch, and features low content of free formaldehyde, resulting in low environmental pollution.

Description

A kind of low-poison urea-formaldehyde resin adhesive and production method thereof

The present invention relates to a kind of low-poison urea-formaldehyde resin adhesive and production method thereof, be mainly used in wood working, be particularly suitable for doing glued board, light body plate etc., also can be used for making shaving board, medium density fibre board (MDF) etc.

The ultimate principle of urea-formaldehyde resin production is that urea and formaldehyde solution are carried out addition reaction and generated methylolurea under the catalysis of alkali, carries out polycondensation then under the catalysis of acid and forms resin.In this process, the generation of dimethylolurea is particularly important, because there is the generation of dimethylolurea that the possible of the resin crosslinks of making just arranged in reaction, and the generation of dimethylolurea and quantity thereof are relevant with the mol ratio of urea and formaldehyde.Therefore change the urea and the formaldehyde mole ratio of different steps in the urea-formaldehyde resin production process, obtain the dimethylolurea of different quantities, thereby change the performance of urea-formaldehyde resin.In existing urea-formaldehyde resin production technology, people adopt weak base → weak acid → weak base operational path usually, carry out addition reaction at urea and formaldehyde under the catalysis at alkali and generate the methylolurea stage, and urea and formaldehyde mole ratio are remained unchanged.

In a Chinese patent (notification number CN1121084) specification sheets, described and carried out under a kind of urea and the catalysis of formaldehyde the addition reaction generation methylolurea stage at alkali, change the technology of urea and formaldehyde mole ratio, this technology more complicated, urea divides four addings, and need repeatedly change temperature of reaction; This technology adds polyvinyl alcohol as tackifier in addition, but in the pure directly input of the solid polyethylene reaction solution, is difficult for fully dissolving, the unfused particulate state in various degree or the bulk of flocculating is often arranged, thereby make urea-formaldehyde glue package stability deterioration.Propose to add flour as tackifier at another part Chinese patent (notification number CN1047879) specification sheets, but urea-formaldehyde glue storage period short (6-10 days), and not anti-boiling water.

The purpose of this invention is to provide a kind of low content of free formaldehyde urea-formaldehyde resin adhesive prescription and production method, to improve the performance of urea-formaldehyde resin adhesive, to reduce the environmental pollution that produces in using and to reduce production costs.

The present invention is achieved through the following technical solutions: its composition of described low-poison urea-formaldehyde resin adhesive comprises urea, formaldehyde, trimeric cyanamide, resol and Sumstar 190, wherein the formaldehyde/urea mol ratio is 1.2～2.0: 1, trimeric cyanamide is 1%～3% of a urea gross weight, resol is 0.5%～2.4% of urea and formaldehyde gross weight, and Sumstar 190 is 1%～10% of urea and a formaldehyde gross weight.

Described Sumstar 190 can be cassava Sumstar 190, potato Sumstar 190, Ipomoea batatas Sumstar 190 or maize oxidized starch.

The better ratio of described low-poison urea-formaldehyde resin adhesive component is that the formaldehyde/urea mol ratio is 1.5: 1, and trimeric cyanamide is 2% of a urea gross weight, and resol is 2% of urea and formaldehyde gross weight, and Sumstar 190 is 5% of urea and a formaldehyde gross weight.

The production method of low-poison urea-formaldehyde resin adhesive comprises uses urea, formaldehyde, trimeric cyanamide, resol, Sumstar 190, acetate and sodium hydroxide to do raw material, wherein the formaldehyde/urea mol ratio is 1.2～2.0: 1, trimeric cyanamide is 1%～3% of a urea gross weight, resol is 0.5%～2.4% of urea and formaldehyde gross weight, and Sumstar 190 is 1%～10% of urea and a formaldehyde gross weight;

Technical process is:

A. with the formaldehyde injecting reactor, transfer PH 〉=9, be 2.0～2.2: 1 adding urea for the first time by the formaldehyde/urea mol ratio, and heat up, be incubated 10～120 minutes as for 90～95 ℃;

B. add urea for the second time, making the formaldehyde/urea mol ratio is 1.3～1.9: 1, is incubated 10～80 minutes down at 90～95 ℃ again;

C. transfer reaction solution PH=4.5～5.5, and 90～95 ℃ of following polycondensations 10～80 minutes to reaction end;

D. transfer PH=6.5～7.5 again, add urea for the third time, making the formaldehyde/urea mol ratio finally is 1.2～1.9: 1, and adds trimeric cyanamide, resol and Sumstar 190.

Major advantage of the present invention is: one: the addition reaction stage of urea and formaldehyde carries out under high PH (PH 〉=9) condition, and in this phasic change urea and formaldehyde mole ratio; All remain on this more than 90 ℃ in addition reaction and polycondensation phase temperature.Two: only need to add a small amount of trimeric cyanamide, resol and Sumstar 190 in the production process, the urea-formaldehyde resin adhesive of preparation has the long and resistance to boiling water of the viscosity height, bonding strength height, storage period of free formaldehyde content low (≤0.3%), Resin adhesive and can wait advantage well and produce cost lower, can effectively reduce the environmental pollution that produces in the use.

Below in conjunction with embodiment in detail technology contents of the present invention is described in detail:

Embodiment 1:

In reactor, add urea and the urea first time, making the formaldehyde/urea mol ratio is 2.0: 1, transfer PH=9.0～9.5, temperature of reaction is controlled at 90～92 ℃, be incubated 20～40 minutes, add urea for the second time then, making the formaldehyde/urea mol ratio is 1.8: 1, be incubated 5～20 minutes down at 90～92 ℃ again, transfer reaction solution PH=4.9～5.1, and 90～92 ℃ of following polycondensations 10～30 minutes to reaction end, make PH=6.5～7.5 again, cool to 80～85 ℃ then, vacuum hydro-extraction adds urea for the third time after viscosity meets the requirements, making the formaldehyde/urea mol ratio finally is 1.5: 1, and adds trimeric cyanamide (be urea gross weight 2%), resol (be urea and formaldehyde gross weight 2%), oxidized tapioca (be urea and formaldehyde gross weight 4%), continue reaction 20～40 minutes down at 60～70 ℃, transfer PH between 7～8, cooling discharging.

Low-poison urea-formaldehyde resin adhesive (1) technical indicator:

Outward appearance: oyster white

Technical indicator: viscosity: 80～600 centipoises

Solid content: 50～75%

Free formaldehyde :≤0.3%

PH： 7～8

Storage period: 〉=3 months

Dry glue intensity: 〉=26MPa (with the test of standard pine piece)

Resistance to boiling water: bonding standard pine piece sample is put into boiling water boiled 3 hours, bonding strength 〉=6Mpa is surveyed in oven dry then

Embodiment 2:

Production technique is with embodiment 1, but the adjustment additive types, with the oxidized tapioca in the oxidised maize starch alternate embodiment 1, technical target of the product is as follows:

Outward appearance: oyster white

Technical indicator: viscosity: 80～600 centipoises

Solid content: 50～75%

Free formaldehyde :≤0.3%

PH： 7～8

Storage period: 〉=3 months

Dry glue intensity: 〉=24MPa (with the test of standard pine piece)

Resistance to boiling water: bonding standard pine piece sample is put into boiling water boiled 3 hours, bonding strength 〉=6Mpa is surveyed in oven dry then

Embodiment 3:

Production technique is with embodiment 1, but improves the add-on of urea for the third time, and making the formaldehyde/urea mol ratio finally is 1.3: 1, and its product performance are as follows:

Outward appearance: oyster white

Technical indicator: viscosity: 80～600 centipoises

Solid content: 50～75%

Free formaldehyde :≤0.15%

PH： 7～8

Storage period: 〉=2 months

Dry glue intensity: 〉=20MPa (with the test of standard pine piece)

Resistance to boiling water: bonding standard pine piece sample is put into boiling water boiled 3 hours, bonding strength 〉=4Mpa is surveyed in oven dry then

Embodiment 4:

Production technique is with embodiment 1, but reduces the add-on of urea for the third time, and making the formaldehyde/urea mol ratio finally is 1.65: 1, and its product performance are as follows:

Outward appearance: oyster white

Technical indicator: viscosity: 200～1000 centipoises

Solid content: 55～75%

Free formaldehyde :≤0.3%

PH： 7～8

Storage period: 〉=5 months

Dry glue intensity: 〉=28MPa (with the test of standard pine piece)

Resistance to boiling water: bonding standard pine piece sample is put into boiling water boiled 3 hours, bonding strength 〉=8Mpa is surveyed in oven dry then

Claims (4)

1. its composition of low-poison urea-formaldehyde resin adhesive comprises urea, formaldehyde, trimeric cyanamide, resol and Sumstar 190, wherein the formaldehyde/urea mol ratio is 1.2～2.0: 1, trimeric cyanamide is 1%～3% of a urea gross weight, resol is 0.5%～2.4% of urea and formaldehyde gross weight, and Sumstar 190 is 1%～10% of urea and a formaldehyde gross weight.

2. low-poison urea-formaldehyde resin adhesive according to claim 1 is characterized in that described Sumstar 190 can be cassava Sumstar 190, potato Sumstar 190, Ipomoea batatas Sumstar 190 or maize oxidized starch.

3. low-poison urea-formaldehyde resin adhesive according to claim 1, the ratio that it is characterized in that described component is formaldehyde/urea mol ratio 1.5: 1, trimeric cyanamide is 2% of a urea gross weight, and resol is 2% of urea and formaldehyde gross weight, and Sumstar 190 is 5% of urea and a formaldehyde gross weight.

4. the production method of a low-poison urea-formaldehyde resin adhesive, it is characterized in that using urea, formaldehyde, trimeric cyanamide, resol, Sumstar 190, acetate and sodium hydroxide to do raw material, wherein the formaldehyde/urea mol ratio is 1.2～2.0: 1, trimeric cyanamide is 1%～3% of a urea gross weight, resol is 0.5%～2.4% of urea and formaldehyde gross weight, and Sumstar 190 is 1%～10% of urea and a formaldehyde gross weight;

Technical process is:

A. with the formaldehyde injecting reactor, transfer PH 〉=9, be 2.0～2.2: 1 adding urea for the first time by the formaldehyde/urea mol ratio, and heat up, be incubated 10～120 minutes as for 90～95 ℃;

B. add urea for the second time, making the formaldehyde/urea mol ratio is 1.3～1.9: 1, is incubated 10～80 minutes down at 90～95 ℃ again;

C. transfer reaction solution PH=4.5～5.5, and 90～95 ℃ of following polycondensations 10～80 minutes to reaction end;

D. transfer PH=6.5～7.5 again, add urea for the third time, making the formaldehyde/urea mol ratio finally is 1.2～1.9: 1, and adds trimeric cyanamide, resol and Sumstar 190.