Hyperbranched polyamide modifier, modified melamino-formaldehyde resin and application

Abstract

The invention discloses a hyperbranched polyamide modifier, modified melamino-formaldehyde resin and application, and belongs to the technical field of modification of melamino-formaldehyde resin. The modifier is prepared from tetraethylenepentamine, ethylenediaminetetraacetic acid, a catalyst and water; the molar ratio of the tetraethylenepentamine to the ethylenediaminetetraacetic acid is 1: (0.3-1); the dosage of the catalyst is 0.5-1.5 wt% of the total mass of the tetraethylenepentamine and the ethylenediaminetetraacetic acid. The hyperbranched polyamide modifier prepared by the invention can be blended and compatible with melamine formaldehyde resin, the toughness is improved, and the formaldehyde release is properly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of modification of melamine formaldehyde resin, in particular to a hyperbranched polyamide modifier, modified melamine formaldehyde resin and application thereof. Background Art

[0002] Melamine formaldehyde resin, also known as melamine resin, is a linear or branched macromolecular compound obtained by the condensation of melamine and formaldehyde, and is a thermosetting resin. In the wood processing industry, plain base paper or printed decorative paper is impregnated with melamine formaldehyde resin and dried to a certain degree to obtain a film paper with a certain resin content. Pasting the film paper on the artificial board substrate through a hot pressing process can beautify the appearance of the substrate, improve the physical properties of the substrate, and increase the value of the artificial board. However, the cross-linking density of melamine formaldehyde resin is large and contains a large number of rigid triazine ring structures, which makes the cured resin brittle and prone to cracking under stress, limiting its industrial promotion and application. Studies have confirmed that by adding a toughening modifier to blend or react with melamine formaldehyde resin to extend the distance between triazine rings to achieve a toughening effect, while not destroying the original dimensional stability of melamine formaldehyde resin, its impact resistance and fatigue resistance are improved. There are many methods to toughen melamine formaldehyde resin, but not all of them are suitable for melamine formaldehyde resin for impregnation. The toughening modification of impregnating resin should adapt to the production conditions of film paper. Attention should also be paid to the viscosity of the modified resin before curing (the viscosity of the resin for impregnating film paper should be preferably below 20s), permeability, pre-curing degree, etc.

[0003] The modification of melamine formaldehyde resin is usually obtained by adding a modifier (toughening agent) to participate in a chemical reaction during the preparation of melamine formaldehyde resin, such as CN107522830A, CN102875755A, CN117683194A, etc., but the preparation process is complicated. Alternatively, a new type of modifier is prepared, and then the modifier is added to the melamine formaldehyde resin system, and it can be directly mixed and used on site, such as CN118126310A, but the storage period of the modifier is short, and the high molecular weight long-chain polymer has a long molecular chain and a strong interaction force between molecules, resulting in a high viscosity and poor fluidity, which is difficult to adapt to the production conditions of film paper. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a hyperbranched polyamide modifier, a modified melamine formaldehyde resin and applications. The amino-terminated hyperbranched polyamide modifier prepared by the present invention presents an irregular three-dimensional spherical structure, has large gaps inside the molecule, can be blended and compatible with the melamine formaldehyde resin, enhances toughness to a certain extent and appropriately reduces formaldehyde release.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] On the one hand, the present invention provides a hyperbranched polyamide modifier, which is prepared from tetraethylene pentamine, ethylenediaminetetraacetic acid, a catalyst and water; the molar ratio of the tetraethylene pentamine to the ethylenediaminetetraacetic acid is 1:(0.3-1); the amount of the catalyst is 0.5-1.5wt% of the total mass of the tetraethylene pentamine and the ethylenediaminetetraacetic acid.

[0007] Furthermore, the catalyst is one or a mixture of p-toluenesulfonic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, and 4-dimethylaminopyridine.

[0008] Preferably, the catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide.

[0009] The present invention also provides a method for preparing the hyperbranched polyamide modifier, comprising: uniformly mixing tetraethylenepentamine, ethylenediaminetetraacetic acid and water, heating, adding a catalyst, reacting for a period of time, performing a dehydration reaction, and then placing in a water bath and cooling to room temperature.

[0010] Furthermore, the above preparation method specifically comprises:

[0011] 1) Evenly mix tetraethylenepentamine, ethylenediaminetetraacetic acid and water, and heat to 135-145℃;

[0012] 2) Add catalyst and react for 0.5-1 hour;

[0013] 3) Raise the temperature to 155-165°C and react for 0.5-1 hour;

[0014] 4) Raise the temperature to 170°C and perform dehydration reaction for 0.5-1 hour;

[0015] 5) Cool down to 90-110℃, add water to adjust the solid content of the modifier to 20-60%, then place in a water bath and quickly cool to room temperature.

[0016] Preferably, in step 1), the amount of water used is 15-20 wt % of the total mass of tetraethylenepentamine, ethylenediaminetetraacetic acid and water.

[0017] On the other hand, the present invention provides a modified melamine formaldehyde resin, which is composed of the following components in percentage by mass: 97.95 wt % of melamine formaldehyde resin, 2 wt % of the above-mentioned modifier, and 0.05 wt % of a curing agent.

[0018] The preparation method of the modified melamine formaldehyde resin comprises mixing the melamine formaldehyde resin, the modifier and the curing agent in a high-speed dispersing homogenizer.

[0019] In another aspect, the present invention also provides the use of the modified melamine formaldehyde resin in impregnating paper veneer panels.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The hyperbranched polyamide modifier prepared by the reaction of tetraethylenepentamine and ethylenediaminetetraacetic acid has a unique three-dimensional spherical molecular structure, which is not easy to be entangled, and the interaction between molecules is weak, so that the molecules can move relatively freely and show low viscosity; and can be blended and compatible with melamine formaldehyde resin, to a certain extent, enhance toughness and appropriately reduce formaldehyde release, so that the prepared impregnated film paper veneer plywood has better mechanical properties. The modifier of the present invention is safe and simple to prepare, has a high yield, and a relatively low cost, and is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the infrared spectrum of the hyperbranched polyamide modifier prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0024] In the present invention, the materials and reagents used can be obtained from commercial sources unless otherwise specified. Among them, the melamine formaldehyde resin (solid content ≥ 50%) and curing agent used below are from Hangzhou Tianyuan Chengda Decoration Materials Co., Ltd. The purity of tetraethylenepentamine is 95%, and the purity of ethylenediaminetetraacetic acid is 99.5%; the catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide.

[0025] The present invention provides a hyperbranched polyamide modifier, a modified melamine formaldehyde resin and applications, and specific embodiments are as follows.

[0026] Example 1

[0027] A method for preparing a hyperbranched polyamide modifier comprises:

[0028] 1) In a 2L flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet and outlet, tetraethylenepentamine, ethylenediaminetetraacetic acid, and water were uniformly mixed under a nitrogen atmosphere and heated to 140°C;

[0029] 2) Add the catalyst 1-ethyl-(3-dimethylaminopropyl)carbodiimide and react for 0.5 hours;

[0030] 3) Raise the temperature to 160°C and react for 0.5 hours;

[0031] 4) Raise the temperature to 170°C and perform dehydration reaction for 0.5 hours;

[0032] 5) Cool down to 90-110℃, add 200g water and mix evenly, then place in a water bath and quickly cool to room temperature;

[0033] 6) Adjust the modifier solid content to 50%.

[0034] The infrared spectrum of the prepared modifier is shown in Figure 1 As shown, the prepared modifier has amide characteristic peaks, which proves that the hyperbranched polyamide modifier is successfully prepared.

[0035] A modified melamine formaldehyde resin is composed of the following components in percentage by mass: 97.95wt% melamine formaldehyde resin, 2wt% of the above modifier, and 0.05wt% of a curing agent; the three are mixed and uniformly mixed using a high-speed dispersing homogenizer (4000r / min, 5min).

[0036] Example 2-Example 4

[0037] In Examples 2-4, the amounts of the various raw materials of the modifier are shown in Table 1, and the other conditions are the same as in Example 1.

[0038] The amount of each component of the modified melamine formaldehyde resin is shown in Table 2.

[0039] Table 1

[0040]

[0041] Table 2

[0042]

[0043] To further illustrate the beneficial effects of the present invention, due to limited space, only Example 1 is taken as an example to construct a comparative example as follows.

[0044] Comparative Example 1

[0045] An unmodified melamine formaldehyde resin: 500 grams of melamine formaldehyde resin and 2.5 grams of curing agent. The melamine formaldehyde resin and the curing agent are mixed uniformly using a high-speed dispersing homogenizer (4000 r / min, 5 min).

[0046] Comparative Example 2

[0047] In this comparative example, tetraethylenepentamine was replaced by an equal molar amount of diethylenetriamine, and the other conditions were the same as in Example 1.

[0048] Comparative Example 3

[0049] In this comparative example, tetraethylenepentamine was replaced by an equal molar amount of triethylenetetramine, and the other conditions were the same as in Example 1.

[0050] Comparative Example 4

[0051] In this comparative example, ethylenediaminetetraacetic acid was replaced by an equal molar amount of sebacic acid, and the other conditions were the same as those in Example 1.

[0052] Comparative Example 5

[0053] In this comparative example, ethylenediaminetetraacetic acid was replaced by an equal molar amount of 1,2,3-propanetricarboxylic acid, and the other conditions were the same as in Example 1.

[0054] Comparative Example 6

[0055] In step 1) of this comparative example, 189.3 g of tetraethylenepentamine, 584.49 g of ethylenediaminetetraacetic acid and 158 g of water were used. In step 2), 3.9 g of catalyst was used. The other conditions were the same as those in Example 1.

[0056] Comparative Example 7

[0057] In this comparative example, ethylenediaminetetraacetic acid was replaced by an equal molar amount of citric acid, and the other conditions were the same as in Example 1.

[0058] Comparative Example 8

[0059] In this comparative example, ethylenediaminetetraacetic acid was replaced by a mixture of ethylenediaminetetraacetic acid and citric acid in equal molar amounts (the molar ratio of ethylenediaminetetraacetic acid to citric acid was 1:1, and the sum of the molar amounts of the two was equal to the molar amount of ethylenediaminetetraacetic acid in Example 1), and the other conditions were the same as in Example 1.

[0060] Comparative Example 9

[0061] In this comparative example, the amount of the modifier is 8%, and the other conditions are the same as those in Example 1.

[0062] Comparative Example 10

[0063] In this comparative example, the amount of modifier used is 8%, and the other conditions are the same as those of comparative example 3.

[0064] According to GB / T 14074-2017 “Test methods for adhesives and resins for wood industry”, the appearance, solid content, viscosity and free formaldehyde of the melamine formaldehyde resins of Examples 1-4 and Comparative Examples 1-10 were tested, and the test results are shown in Table 3.

[0065] Table 3

[0066]

[0067] As can be seen from the above table, the modified melamine formaldehyde resin prepared by the present invention is a light yellow transparent liquid with a viscosity of 14.42-15.65s and a free formaldehyde content of 0.18-0.44%. The viscosity is relatively low, which can meet the production conditions of impregnated film paper and has a low free formaldehyde content. The viscosity of pure melamine formaldehyde resin (Comparative Example 1) is lower, but its formaldehyde content is relatively high, which is not conducive to environmental protection; replacing tetraethylene pentamine with diethylene triamine (Comparative Example 2) or triethylene tetraamine (Comparative Example 3), the viscosity of the obtained resin is slightly improved, and the free formaldehyde content is increased by more than 65% compared with Example 1; replacing ethylenediamine tetraacetic acid with sebacic acid (Comparative Example 4) increases the viscosity by 61.5%, and the free formaldehyde content increases by 39%; replacing ethylenediamine tetraacetic acid with 1,2,3-propane tricarboxylic acid (Comparative Example 5), the viscosity is not significantly improved, but the free formaldehyde content is high; changing the formula dosage of the modifier (Comparative Example 6), its viscosity is improved, and the free formaldehyde content is also improved. Replacing all or part of ethylenediamine tetraacetic acid with citric acid (Comparative Examples 7-8), the viscosity and free formaldehyde content are not much different from the examples; increasing the dosage of the modifier (Comparative Examples 9-10) will lead to a significant increase in the viscosity of the prepared resin.

[0068] The melamine formaldehyde resins of Examples 1-6 and Comparative Examples 1-10 of the present invention were used to prepare impregnated adhesive film paper, respectively. The base paper was impregnated in the resin adhesive of the examples and comparative examples, and the impregnation amount was 110-170%. The impregnated base paper was dried at a drying temperature of 120° C. to obtain the impregnated adhesive film paper of the examples and comparative examples.

[0069] The impregnated film paper of the present invention and the comparative example were used to prepare the impregnated film paper facing plywood, as follows:

[0070] 1) Plywood: moisture content 8-12%, bonding strength 0.9Mpa;

[0071] 2) Hot pressing: temperature 120°C, pressure 1.0 MPa, time 6 min.

[0072] The physical and chemical properties of impregnated paper veneer plywood and blockboard were tested according to GB / T 34722-2017. The test results are shown in Table 4-Table 5.

[0073] Table 4

[0074]

[0075] The test results show that the impregnated film paper prepared by the modified melamine formaldehyde resin of the present invention has greatly improved toughness, which is reflected in the fact that the cracking grade reaches level 5, the tensile strength reaches 68.49N, and the elongation at break reaches 15.56%; the wear value is reduced, and the surface hardness and scratch resistance are improved; the surface does not crack, blister, discolor, wrinkle, etc. during the cold and hot cycle. The impregnated film paper prepared by the modified melamine formaldehyde resin of the present invention meets the requirements of GB / T 34722-2017 "Impregnated Film Paper Veneer Plywood and Blockboard".

[0076] Table 5

[0077]

[0078] It can be seen from Table 5 that the surface of pure melamine formaldehyde resin (Comparative Example 1) will have cracks, bubbling, discoloration, wrinkling and the like during the cold and hot cycle, and the tensile strength and elongation at break are greatly reduced; when tetraethylene pentamine is replaced by diethylene triamine (Comparative Example 2) or triethylene tetraamine (Comparative Example 3), the wear value increases, and the tensile strength and elongation at break are greatly reduced; when ethylenediaminetetraacetic acid is replaced by sebacic acid (Comparative Example 4), the performance in all aspects is not much different from that in the embodiment, but the viscosity is high and it is not easy to impregnate evenly; when ethylenediaminetetraacetic acid is replaced by 1,2,3-propanetricarboxylic acid (Comparative Example 5), the cracking grade, tensile strength and elongation at break are all greatly reduced; the plywood prepared in Comparative Examples 6-10 all have some poor performance.

[0079] In summary, the hyperbranched polyamide modifier prepared by the reaction of tetraethylenepentamine and ethylenediaminetetraacetic acid has a low viscosity and can be blended and compatible with melamine formaldehyde resin, which can enhance toughness to a certain extent and appropriately reduce formaldehyde release, so that the prepared impregnated film paper veneer plywood has better mechanical properties. The modifier of the present invention is safe and simple to prepare, has a high yield, and a relatively low cost, and is easy to realize industrial production.

[0080] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, making several improvements and modifications without departing from the principles of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A hyperbranched polyamide modifier, characterized in that: The modifier is prepared from tetraethylene pentamine, ethylenediaminetetraacetic acid, a catalyst and water; the molar ratio of the tetraethylene pentamine to the ethylenediaminetetraacetic acid is 1:(0.3-1); the amount of the catalyst is 0.5-1.5wt% of the total mass of the tetraethylene pentamine and the ethylenediaminetetraacetic acid.

2. The hyperbranched polyamide modifier according to claim 1, characterized in that The catalyst is one or a mixture of p-toluenesulfonic acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide and 4-dimethylaminopyridine.

3. The hyperbranched polyamide modifier according to claim 2, characterized in that The catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide.

4. The method for preparing the hyperbranched polyamide modifier according to any one of claims 1 to 3, characterized in that: include: Evenly mix tetraethylenepentamine, ethylenediaminetetraacetic acid and water, raise the temperature, then add a catalyst, react for a period of time, perform a dehydration reaction, and then place in a water bath and cool to room temperature.

5. The method for preparing the hyperbranched polyamide modifier according to claim 4, characterized in that: The preparation method specifically comprises: 1) Evenly mix tetraethylenepentamine, ethylenediaminetetraacetic acid and water, and heat to 135-145℃; 2) Add catalyst and react for 0.5-1 hour; 3) Raise the temperature to 155-165°C and react for 0.5-1 hour; 4) Raise the temperature to 170°C and perform dehydration reaction for 0.5-1 hour; 5) Cool down to 90-110℃, add water to adjust the solid content of the modifier to 20-60%, then place in a water bath and quickly cool to room temperature.

6. The preparation method according to claim 5, characterized in that: In the step 1), the amount of water used is 15-20 wt% of the total mass of tetraethylenepentamine, ethylenediaminetetraacetic acid and water.

7. A modified melamine formaldehyde resin, characterized in that: The invention is composed of the following components in percentage by weight: 94.9-99.45 wt % of melamine formaldehyde resin, 0.5-5 wt % of the modifier according to any one of claims 1-3, and 0.05-0.1 wt % of a curing agent.

8. The modified melamine formaldehyde resin according to claim 7, characterized in that The invention is composed of the following components in percentage by weight: 97.95 wt % of melamine formaldehyde resin, 2 wt % of the modifier according to any one of claims 1 to 3, and 0.05 wt % of a curing agent.

9. The method for preparing the modified melamine formaldehyde resin according to claim 7 or 8, characterized in that: The melamine formaldehyde resin, the modifier according to any one of claims 1 to 3, and the curing agent are uniformly mixed in a high-speed dispersing homogenizer.

10. Use of the modified melamine formaldehyde resin according to claim 7 or 8 in impregnating paper veneer panels.

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