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Urea-dialdehyde starch-formaldehyde copolycondensed resin adhesive and preparation method therefor

A technology of co-condensation resin and dialdehyde starch, which is applied in the field of wood adhesives, can solve problems such as poor bonding performance and water resistance, high free formaldehyde content, and harm to health, and achieve excellent water resistance, reduce free formaldehyde content, The effect of short curing time

Active Publication Date: 2019-04-12
CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, urea-formaldehyde resin adhesives have defects such as high free formaldehyde content, poor bonding performance and water resistance, and high brittleness. The biggest defect is that it will release a large amount of formaldehyde after it is used in wood-based panels, which will endanger people's health.
In the prior art, methods such as reducing the molar ratio of formaldehyde / urea, optimizing the synthesis process, adding various modifiers, and rationally selecting curing agents can effectively reduce the content of free formaldehyde and improve performance such as bonding strength, but these methods are based on At the expense of increasing production costs or reducing other properties of resin adhesives

Method used

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  • Urea-dialdehyde starch-formaldehyde copolycondensed resin adhesive and preparation method therefor

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Effect test

Embodiment 1

[0030] A urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of the present invention, in parts by weight, its raw material components include: 60.06 parts of urea, 146.09 parts of formaldehyde aqueous solution with a mass fraction of 37%, 16.2 parts of aldehyde group content ≥80% dialdehyde starch, 0.6 parts melamine and 64.8 parts water.

[0031] The preparation method of the urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of this embodiment comprises the following steps:

[0032] (1) Dissolve 16.2 parts by weight of dialdehyde starch in 64.8 parts by weight of water, prepare a dialdehyde starch milk solution with a mass fraction of 20%, add it to the reactor, and raise the temperature of the reactor to 60°C to make the dialdehyde starch paste After 0.5h, gelatinized dialdehyde starch milk solution was obtained.

[0033] (2) Adjust the pH value of the gelatinized dialdehyde starch milk solution obtained in step (1) to 9.0 using an aqueous s...

Embodiment 2

[0039] A urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of the present invention, in parts by weight, its raw material components include: 60.06 parts of urea, 97.39 parts of formaldehyde aqueous solution with a mass fraction of 37%, 48.6 parts of aldehyde group content ≥80% dialdehyde starch, 1.8 parts melamine and 121.5 parts water.

[0040] The preparation method of the urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of this embodiment comprises the following steps:

[0041] (1) Dissolve 48.6 parts by weight of dialdehyde starch in 72.9 parts by weight of water, prepare a dialdehyde starch milk solution with a mass fraction of 40%, add it to the reactor, and raise the temperature of the reactor to 70°C to make the dialdehyde starch paste After 1 h, gelatinized dialdehyde starch milk solution was obtained.

[0042] (2) Adjust the pH value of the gelatinized dialdehyde starch milk solution obtained in step (1) to 8.5 using an aqueous so...

Embodiment 3

[0047] A urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of the present invention, in parts by weight, its raw material components include: 60.06 parts of urea, 40.58 parts of formaldehyde aqueous solution with a mass fraction of 37%, 81 parts of aldehyde group content ≥80% dialdehyde starch, 3 parts melamine and 189 parts water.

[0048] The preparation method of the urea-dialdehyde starch-formaldehyde co-condensation resin adhesive of this embodiment comprises the following steps:

[0049] (1) Dissolve 81 parts by weight of dialdehyde starch in 189 parts by weight of water, prepare a dialdehyde starch emulsion solution with a mass fraction of 30%, add it to the reactor, raise the temperature of the reactor to 80°C, and make the dialdehyde starch paste After 2 h, gelatinized dialdehyde starch milk solution was obtained.

[0050] (2) Adjust the pH value of the gelatinized dialdehyde starch milk solution obtained in step (1) to 8.0 using 30% sodium hydroxide...

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Abstract

The invention discloses a urea-dialdehyde starch-formaldehyde copolycondensed resin adhesive and a preparation method therefor. The preparation method comprises the steps: (1) gelatinizing dialdehydestarch; (2) adjusting a pH value of the gelatinized starch, adding urea, heating the temperature of the mixture to 85 DEG C to 95 DEG C, carrying out a reaction for 0.5 to 1.5 hours while carrying outheat preservation, and then, cooling the temperature of the reacted substance to 35 DEG C to 45 DEG C; (3) adjusting a pH value of the mixture obtained in the step (2), adding formaldehyde and melamine, then, heating the temperature of the mixture to 85 DEG C to 95 DEG C, and carrying out a reaction for 0.5 to 1 hour while carrying out heat preservation; (4) adjusting a pH value of the mixture obtained in the step (3), and carrying out a reaction until the viscosity of the mixture is 20s to 60s; and (5) adjusting a pH value of the mixture obtained in the step (4), adding the urea, cooling thetemperature of the mixture to 80 DEG C to 85 DEG C, carrying out a reaction for 0.5 to 1 hour while carrying out heat preservation, and then, carrying out cooling and discharging. The adhesive prepared by the method is excellent in adhesion and water resistance, can meet the requirements of wood, bamboo and straws on bonding and can be applied to the production and manufacturing of veneers, shaving boards, fiber boards, lumber core plywood and furniture.

Description

technical field [0001] The invention relates to the technical field of wood adhesives, in particular to an environment-friendly urea-dialdehyde starch-formaldehyde co-condensation resin adhesive and a preparation method thereof. Background technique [0002] Urea-formaldehyde resin adhesive is formed by polycondensation of urea and formaldehyde under the action of alkaline or acidic catalysts. It has the advantages of simple preparation process, low production cost, fast curing speed, excellent bonding performance, and convenient operation. It has been widely used in particleboard. , Medium density fiberboard, plywood and other wood-based panels and interior home furniture decoration industries, its demand exceeds 90% of the total glue used in the wood industry. However, urea-formaldehyde resin adhesives have defects such as high free formaldehyde content, poor bonding performance and water resistance, and high brittleness. The biggest defect is that it will release a large ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09J161/32C08G12/40
CPCC08G12/40C09J161/32
Inventor 左迎峰李萍吴义强袁光明屠茹茹王健李文豪周亚
Owner CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
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