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Urea-formaldehyde adhesive with low free formaldehyde and expanding characteristic and its preparation method

A technology with low free formaldehyde and formaldehyde, applied in adhesives, aldehyde/ketone condensation polymer adhesives, adhesive types, etc., can solve the problems of increasing resin cost, affecting the mechanical properties and performance of adhesives and their products, etc. To achieve the effect of excellent storage performance

Inactive Publication Date: 2005-07-20
倪卓
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The introduction of these additives will increase the cost of the resin and affect the mechanical properties and performance of the adhesive and its products

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Add appropriate proportions of formaldehyde, urea, additives and water to the reactor, and the molar ratio of formaldehyde / urea is 1.9-2.3. The mixture is reacted under the action of acid (pH 6.5 to 7.5), the temperature is at 60° C. for 1 hour, 70° C. for 1 hour, and 90° C. for 1.5 hours. When the viscosity reaches 40 cps, the second-stage reaction is carried out. Adjust the molar ratio of formaldehyde / urea to 1.9 to 2.3, and react the mixture under a base catalyst (PH is 7.0 to 8.5), 0.5 hours at 70°C, 1 hour at 80°C, 1 hour at 90°C, and when the viscosity reaches 150cps, the mixture is slowly cool down. If necessary, the pH value can be adjusted to between 7.5 and 8.5 to obtain urea-formaldehyde resin.

[0013] The prepared urea-formaldehyde resin has the following typical properties:

[0014] Solid content 50%

[0015] Viscosity 150cps

[0016] pH 8.0

[0017] Specific gravity 1.22g / ml

[0018] Free formaldehyde 0.1%

[0019] Storage period 60 days

Embodiment 2

[0021] The urea-formaldehyde resin in Example 1 is sent into the feeding tank of the spray dryer, and the liquid glue is sent into the high-speed centrifugal atomizer by the speed-regulating feed pump, and the misty glue enters the drying main tower and is heated by the hot air from the heating furnace. When heated (180°C), the moisture in the glue liquid evaporates quickly, and part of the powdered glue falls into the lower part of the drying tower (100°C), and the residence time is about 10 seconds. The prepared powder urea-formaldehyde adhesive has the following characteristics:

[0022] Appearance white powder

[0023] Particle size <80 mesh

[0024] Moisture content 5%

[0025] Apparent density 0.2

[0026] Formaldehyde content <0.4%

[0027] Storage period 1 year

Embodiment 3

[0029] Performance testing items

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Abstract

The urea formaldehyde resin prepared through one sectioned process with formaldehyde and urea as main material and in the presence of Lewis acid or alkali has free formaldehyde content of about 0.1 % and less than 0.5 %. During the preparation, organic amine assistant is added, and this makes the adhesive possess obvious expansion performance during formation and be suitable for use in producing various kinds of board. The products with the adhesive have low formaldehyde release amount, excellent mechanism performance, excellent weather resistance, etc. The liquid resin may be spray dried to prepare urea formaldehyde adhesive powder capable of maintaining reaction activity for long time. The adhesive of the present invention has no need of adding formaldehyde trapping agent.

Description

1. Technical field [0001] The present invention discloses a process for the preparation of waterborne low free formaldehyde urea-formaldehyde resins based on urea and formaldehyde, which can be used to form industrial articles with limited formaldehyde release; due to the pronounced swelling properties of the adhesive when cured, it is especially suitable for Manufacture of various panel products such as particle board, fibreboard and plywood. The powder urea-formaldehyde resin prepared by dry spraying process maintains the characteristics of liquid urea-formaldehyde resin and also has excellent storage performance. 2. Technical background [0002] Urea-formaldehyde resin adhesives are widely used in many fields of industry and life. Urea-formaldehyde resin has the advantages of low cost, good reactivity, and convenient processing. In the production process, the curing speed of the resin can be adjusted by adding a catalyst (resin hardener), so the production capacity is gr...

Claims

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Application Information

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IPC IPC(8): C08G14/08C09J161/24
Inventor 倪卓
Owner 倪卓
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