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A kind of melamine-urea co-condensation resin and its preparation method and an adhesive

A melamine, co-condensation technology, applied in aldehyde/ketone condensation polymer adhesives, adhesives, adhesive types and other directions, can solve the problems of increasing production costs, increasing difficulty in promotion, etc., achieving good water resistance and reducing formaldehyde. The effect of high release and solid content

Inactive Publication Date: 2019-06-11
NORTHEAST FORESTRY UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the traditional process, that is, the synthesis process of alkali-acid-alkali, needs to add a large amount of melamine to meet the standards of water boiling resistance and low formaldehyde release, which increases the production cost and makes it difficult to promote the resin.

Method used

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  • A kind of melamine-urea co-condensation resin and its preparation method and an adhesive
  • A kind of melamine-urea co-condensation resin and its preparation method and an adhesive
  • A kind of melamine-urea co-condensation resin and its preparation method and an adhesive

Examples

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preparation example Construction

[0028] The invention provides a method for preparing a melamine-urea co-condensation resin, which comprises the following steps:

[0029] Mixing polyvinyl alcohol and formaldehyde to perform a first polycondensation reaction to obtain a first polycondensation product;

[0030] Mixing the first polycondensation product with melamine under the condition of a pH value of 5.3 to 5.6 to perform a second polycondensation reaction to obtain a second polycondensation product;

[0031] Under the condition of a pH value of 6.5 to 7.5, mixing the second polycondensation product with the first batch of urea, and performing a third polycondensation reaction to obtain a third polycondensation product;

[0032] Under the condition of a pH of 8.3 to 8.7, mixing the third polycondensation product with the second batch of urea, and performing a fourth polycondensation reaction to obtain a fourth polycondensation product;

[0033] The fourth polycondensation product is mixed with the third batch of urea, ...

Embodiment 1

[0054] (1) Reagent processing

[0055] Soak polyvinyl alcohol in water overnight for later use.

[0056] (2) Preparation of MUF resin

[0057] 1. Monomer weight ratio: based on the total amount of urea added.

[0058] Polyvinyl alcohol: 1.0~1.3%

[0059] Sodium sulfite: 0.25~0.35%

[0060] Melamine: 39~54%

[0061] F / U 1 =2.10~2.25:1

[0062] F / U 2 =1.6~1.8:1

[0063] F / U 3 =1.25~1.4:1

[0064] 2. MUF resin preparation

[0065] After removing water from polyvinyl alcohol, conduct the first polycondensation reaction with formaldehyde at 50-55°C for 30 minutes to obtain the first polycondensation product; lower the temperature to below 40°C, adjust the pH to 5.3-5.6, add melamine, and wait for it to dissolve at 55- Incubate at 65°C for 30 minutes to perform the second polycondensation reaction to obtain the second polycondensation product; adjust the pH to 6.5-7.5 with sodium hydroxide and add urea U 1 , And the temperature is raised to 85-90℃ within 30~35min, and the third polycondensation re...

Embodiment 2

[0075] In this embodiment, the amount of melamine added accounts for 40% of the total mass of urea. The specific preparation method is as follows:

[0076] (1) Reagent processing

[0077] Soak polyvinyl alcohol in water overnight for later use.

[0078] (2) Preparation of MUF resin

[0079] 1. Monomer weight ratio: based on the total amount of urea added.

[0080] Polyvinyl alcohol: 4.0g

[0081] Sodium sulfite: 1.1g

[0082] Formaldehyde (37% aqueous solution): 625g

[0083] Melamine: 157.2g

[0084] Urea: 393.28g

[0085] F / U 1 = 2.24:1

[0086] F / U 2 =1.75:1

[0087] F / U 3 =1.2:1

[0088] 2. Preparation of MUF resin

[0089] After removing the moisture from the polyvinyl alcohol, perform the first polycondensation reaction with formaldehyde at 53°C for 30 minutes to obtain the first polycondensation product; reduce the temperature to below 40°C, adjust the pH to 5.5, add melamine, and wait for it to dissolve and heat at 60°C for 30 minutes to proceed Two polycondensation reaction to obtain t...

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Abstract

The invention provides a preparation method of melamine-urea cocondensed resin with ultralow formaldehyde release amount. The preparation method comprises the following steps of firstly, enabling polyvinyl alcohol and formaldehyde to generate condensation reaction; adding melamine to react, so as to obtain a second condensed product; adding a first batch of urea, and reacting until the viscosity reaches 350mPa.s, so as to obtain a third polycondensed product; finally, adding the second batch of urea, and reacting, so as to obtain a fourth polycondensed product; after the temperature is reducedto 70 DEG C, enabling the third batch of urea and the fourth polycondensed product to react, so as to obtain the melamine-urea cocondensed resin. The preparation method has the advantages that the melamine is added in the primary reaction period under the acid condition, and the melamine can be dissolved at low temperature; compared with the traditional technology, the resin with bonding strengthgreater than 0.7MPa after 4h of water boiling can be prepared with lower adding amount of melamine, and the release amount of formaldehyde is lower than 0.3mg / L; compared with the traditional technology, the resin synthesizing time is shortened by 0.5 to 1.5h, and the cost is greatly reduced.

Description

Technical field [0001] The invention relates to the technical field of adhesives, in particular to a melamine-urea co-condensation resin, a preparation method thereof, and an adhesive. Background technique [0002] Urea-formaldehyde resin (UF) has the characteristics of cheap and readily available raw materials, convenient production, and high bonding strength. It is widely used in wood bonding such as wood-based panels, particleboards, and medium-density fiberboards. [0003] However, urea-formaldehyde resin has obvious shortcomings in the use process, that is, its water resistance, heat resistance, and aging resistance are poor, and it will release formaldehyde after curing. These shortcomings make urea-formaldehyde resin used in environments with high temperature, high humidity and strict formaldehyde emission requirements. restricted. [0004] It is a key issue for the development and application of melamine-urea co-condensation resin (MUF) adhesives to improve the water resista...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G12/40C08G12/38C09J161/32
CPCC08G12/38C08G12/40C09J161/32
Inventor 顾继友王博张彦华谭海彦
Owner NORTHEAST FORESTRY UNIVERSITY