CN117757394A - Urea-formaldehyde resin adhesive and preparation method thereof - Google Patents
Urea-formaldehyde resin adhesive and preparation method thereof Download PDFInfo
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- CN117757394A CN117757394A CN202311400929.9A CN202311400929A CN117757394A CN 117757394 A CN117757394 A CN 117757394A CN 202311400929 A CN202311400929 A CN 202311400929A CN 117757394 A CN117757394 A CN 117757394A
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- urea
- formaldehyde resin
- resin adhesive
- formaldehyde
- straw
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- GZCGUPFRVQAUEE-SLPGGIOYSA-N aldehydo-D-glucose Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C=O GZCGUPFRVQAUEE-SLPGGIOYSA-N 0.000 title claims abstract description 75
- 229920001807 Urea-formaldehyde Polymers 0.000 title claims abstract description 72
- 239000000853 adhesive Substances 0.000 title claims abstract description 50
- 230000001070 adhesive effect Effects 0.000 title claims abstract description 50
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 138
- 239000010902 straw Substances 0.000 claims abstract description 68
- 239000004368 Modified starch Substances 0.000 claims abstract description 50
- 229920000881 Modified starch Polymers 0.000 claims abstract description 50
- 235000019426 modified starch Nutrition 0.000 claims abstract description 50
- 239000007864 aqueous solution Substances 0.000 claims abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 28
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000004202 carbamide Substances 0.000 claims abstract description 26
- 230000003712 anti-aging effect Effects 0.000 claims abstract description 15
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 11
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 48
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 32
- 229920002472 Starch Polymers 0.000 claims description 17
- 235000019698 starch Nutrition 0.000 claims description 17
- 239000008107 starch Substances 0.000 claims description 17
- 238000002791 soaking Methods 0.000 claims description 16
- 239000000839 emulsion Substances 0.000 claims description 15
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 14
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 14
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 13
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 13
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 230000001105 regulatory effect Effects 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 7
- 238000005406 washing Methods 0.000 claims description 7
- 230000035484 reaction time Effects 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- 238000005303 weighing Methods 0.000 claims description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical group [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 4
- 235000019270 ammonium chloride Nutrition 0.000 claims description 2
- 238000004132 cross linking Methods 0.000 abstract description 9
- 238000010923 batch production Methods 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 7
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 239000003463 adsorbent Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 125000002777 acetyl group Chemical group [H]C([H])([H])C(*)=O 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- QUBQYFYWUJJAAK-UHFFFAOYSA-N oxymethurea Chemical compound OCNC(=O)NCO QUBQYFYWUJJAAK-UHFFFAOYSA-N 0.000 description 2
- 229950005308 oxymethurea Drugs 0.000 description 2
- 239000004094 surface-active agent Substances 0.000 description 2
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000011120 plywood Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
Landscapes
- Phenolic Resins Or Amino Resins (AREA)
Abstract
The invention relates to the technical field of adhesive preparation, and particularly discloses a urea-formaldehyde resin adhesive and a preparation method thereof. The urea-formaldehyde resin adhesive provided by the invention comprises formaldehyde aqueous solution, urea, polyvinyl alcohol, modified straw, an anti-aging agent, a curing agent, modified starch and 4-methylbenzenesulfonic acid. The urea-formaldehyde resin adhesive provided by the invention synthesizes urea-formaldehyde resin by taking formaldehyde aqueous solution and urea as main components, and adds specific modified straw and modified starch, wherein a three-dimensional reticular macromolecular crosslinking structure is formed between the components through crosslinking reaction, so that the cementing strength and water resistance of the urea-formaldehyde resin adhesive are improved, the content of free formaldehyde can be further reduced, the problem of overhigh formaldehyde release in the prior art is fundamentally solved, the usability is good, the process is simple, the operation is easy, and the urea-formaldehyde resin adhesive is suitable for batch production.
Description
Technical Field
The invention relates to the technical field of adhesive preparation, in particular to a urea-formaldehyde resin adhesive and a preparation method thereof.
Background
Currently, there are many methods for reducing formaldehyde emission of artificial boards, such as: using a low formaldehyde or formaldehyde-free adhesive to replace the traditional urea formaldehyde resin; adding formaldehyde adsorbent into the plate to adsorb and fix formaldehyde; selecting a plate subjected to low formaldehyde emission certification. However, alternative adhesives are generally expensive and are not as good as urea-formaldehyde resin in terms of performance and cost; formaldehyde adsorbents often require periodic replacement, increasing maintenance costs, and the performance of the adsorbent is also susceptible to temperature and humidity; the board subjected to low formaldehyde emission certification is more expensive, and the preparation process is complex and the supply is limited. In summary, although the above measures can reduce the formaldehyde content in the artificial board to a certain extent, the cost is still too high or the mass production is difficult. Therefore, the urea-formaldehyde resin adhesive with good water resistance, low formaldehyde content and high cementing strength has important significance.
Disclosure of Invention
In view of the above, the invention provides a urea-formaldehyde resin adhesive and a preparation method thereof, wherein formaldehyde aqueous solution and urea are used as main components to synthesize urea-formaldehyde resin, and specific modified straw and modified starch are added, so that a three-dimensional reticular macromolecular crosslinked structure is formed between the components through crosslinking reaction, the cementing strength and the water resistance of the urea-formaldehyde resin adhesive are improved, the content of free formaldehyde can be further reduced, and the problem of overhigh formaldehyde release in the prior art is fundamentally solved.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
the invention provides a urea-formaldehyde resin adhesive, which comprises the following components in parts by weight: 200-250 parts of formaldehyde aqueous solution, 143-160 parts of urea, 2-5 parts of polyvinyl alcohol, 10-15 parts of modified straw, 5-7 parts of anti-aging agent, 12-14 parts of curing agent, 10-15 parts of modified starch and 12-18 parts of 4-methylbenzenesulfonic acid;
wherein the mass concentration of the formaldehyde aqueous solution is 36.5% -37.5%;
the modified straw is modified by sodium hydroxide aqueous solution, sodium dodecyl benzene sulfonate and sodium dodecyl sulfate;
the modified starch is hydrochloric acid aqueous solution and sodium persulfate modified starch.
Compared with the prior art, the urea-formaldehyde resin adhesive provided by the invention synthesizes urea-formaldehyde resin by taking formaldehyde aqueous solution and urea as main components, and also adds modified straw and modified starch, wherein the modified straw has excellent specific surface area and is loaded with a large number of active groups through adding the straw modified by specific components, can react with free formaldehyde in the urea-formaldehyde resin, and reduces the content of free formaldehyde in the board; the specific modified straw and urea-formaldehyde resin have excellent binding force, and can be combined in the net structure of the urea-formaldehyde resin under the action of 4-methylbenzenesulfonic acid, and hydroxyl in the modified straw, dimethylol urea and oligomers in the urea-formaldehyde resin form an acetal structure, so that the water resistance and the cementing strength of the urea-formaldehyde resin adhesive are further improved; the modified starch has a large number of active hydroxyl groups and other active groups, wherein the active hydroxyl groups can react with formaldehyde to reduce the content of free formaldehyde in the board, the active groups can also have a crosslinking effect with urea-formaldehyde resin, and the cementing strength of the urea-formaldehyde resin adhesive is greatly improved.
The invention synthesizes urea formaldehyde resin by taking formaldehyde aqueous solution and urea as main components, and adds specific modified straw and modified starch, and the components form a three-dimensional reticular macromolecular crosslinked structure through crosslinking reaction, thereby improving the cementing strength and water resistance of the urea formaldehyde resin adhesive, further reducing the content of free formaldehyde, and fundamentally solving the problem of overhigh formaldehyde release in the prior art.
Preferably, the preparation of the modified straw comprises the following steps:
s1, adding a sodium hydroxide aqueous solution into straw, soaking at 30-40 ℃, filtering, washing with water, and drying to obtain primary modified straw;
s2, adding sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water into the primary modified straw, soaking at 50-60 ℃, filtering, washing with water, and drying to obtain the modified straw.
According to the invention, after the straw is modified by sodium hydroxide, the fiber tissue becomes fluffy, and the surface is damaged to a certain extent, so that the specific surface area of the straw is increased, and further, the primary modified straw is soaked in a specific surfactant, the straw modified by sodium hydroxide has excellent specific surface area, the surfactant can be more loaded in the straw, a large number of active groups are provided, and the active groups react with free formaldehyde in urea-formaldehyde resin, so that the content of free formaldehyde in the board is reduced; because the modified straw and the urea-formaldehyde resin have excellent binding force, the modified straw and the urea-formaldehyde resin can be combined in the net structure of the urea-formaldehyde resin, and the hydroxyl in the modified straw, the dimethylol urea and the oligomer in the urea-formaldehyde resin form an acetal structure, so that the water resistance and the cementing strength of the urea-formaldehyde resin adhesive are further improved.
Further preferably, in S1, the particle size of the straw is 15nm-30nm.
Further preferably, in S1, the mass concentration of the aqueous sodium hydroxide solution is 10% -12%.
Further preferably, in S1, the mass ratio of the straw to the sodium hydroxide aqueous solution is 1 (8-10).
Further preferably, in S1, the soaking time is 4h to 5h.
Further preferably, in S2, the mass ratio of the straw to the sodium dodecyl benzene sulfonate to the sodium dodecyl sulfate to the water is 1 (1.8-2.0): (1.3-1.5): (22-26).
Further preferably, in S2, the soaking time is 12h-18h.
Preferably, the preparation of the modified starch comprises the following steps:
step 1, dispersing starch in water, then adding hydrochloric acid aqueous solution, and reacting at 50-55 ℃ to obtain primary modified starch aqueous emulsion;
and step 2, adding sodium persulfate into the primary modified starch aqueous emulsion, reacting at 60-70 ℃, and drying to obtain modified starch.
The invention firstly utilizes the aqueous solution of hydrochloric acid to modify the starch, which is favorable for acidolysis of the hydrochloric acid starch and provides more active groups; further, sodium persulfate is selected as an oxidant to react with primary modified starch, so that active hydroxyl in the primary modified starch can be oxidized into carboxyl, and the carboxyl can react with formaldehyde, so that the content of free formaldehyde in the board is reduced; active groups in the modified starch can also have a crosslinking effect with urea-formaldehyde resin, so that the cementing strength of the urea-formaldehyde resin adhesive is greatly improved.
Further preferably, in step 1, the reaction time is 5h to 8h.
Further preferably, in the step 1, the mass ratio of the starch to the water is 1 (8-10).
Further preferably, in the step 1, the mass concentration of the hydrochloric acid aqueous solution is 1% -3%.
Further preferably, in the step 1, the mass ratio of the starch to the aqueous hydrochloric acid solution is 1 (0.04-0.07).
Further preferably, in step 2, the reaction time is 3h to 5h.
Further preferably, in the step 2, the mass ratio of the primary modified starch aqueous emulsion to the sodium persulfate is 1 (0.1-0.15).
Preferably, the anti-aging agent is an anti-aging agent AW.
Preferably, the curing agent is ammonium chloride.
The second aspect of the invention provides a preparation method of the modified urea-formaldehyde resin adhesive, comprising the following steps:
step a, weighing the components according to the mass ratio, regulating the pH value of the weighed formaldehyde aqueous solution to 7-7.5, then adding polyvinyl alcohol, preserving heat at 50-60 ℃ for 20-30 min, then adding 30-40% of urea, and reacting at 80-90 ℃ for 60-70 min to obtain a first reaction system;
step b, regulating the pH value of the first reaction system to be 4-5, then adding 30% -40% of urea, and reacting at 95-100 ℃ for 50-80 min to obtain a second reaction system;
step c, regulating the pH value of the second reaction system to 7-7.5, then adding the rest urea, and reacting at 50-58 ℃ for 30-40 min to obtain urea-formaldehyde resin;
and d, uniformly mixing the urea-formaldehyde resin, the modified straw, the anti-aging agent, the modified starch and the 4-methylbenzenesulfonic acid at the temperature of 100-120 ℃, then reacting at the temperature of 40-50 ℃, and adding a curing agent after the reaction is completed, and uniformly mixing to obtain the urea-formaldehyde resin adhesive.
Further preferably, in step d, the reaction time is 50min-80min.
The urea-formaldehyde resin adhesive provided by the invention synthesizes urea-formaldehyde resin by taking formaldehyde aqueous solution and urea as main components, and adds specific modified straw and modified starch, wherein a three-dimensional reticular macromolecular crosslinking structure is formed between the components through crosslinking reaction, so that the cementing strength and water resistance of the urea-formaldehyde resin adhesive are improved, the content of free formaldehyde can be further reduced, the problem of overhigh formaldehyde release in the prior art is fundamentally solved, the usability is good, the process is simple, the operation is easy, and the urea-formaldehyde resin adhesive is suitable for batch production.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
The embodiment provides a urea-formaldehyde resin adhesive, which comprises the following components in parts by weight: 200 parts of formaldehyde aqueous solution with the mass concentration of 37%, 143 parts of urea, 2 parts of polyvinyl alcohol, 7 parts of modified straw, 7 parts of anti-aging agent, 12 parts of curing agent, 15 parts of modified starch and 12 parts of 4-methylbenzenesulfonic acid;
wherein, the preparation of the modified straw comprises the following steps:
s1, adding 12% sodium hydroxide aqueous solution into straw with the particle size of 15nm, soaking for 4 hours at 40 ℃, filtering, washing with water, and drying to obtain primary modified straw; wherein the mass ratio of the straw to the sodium hydroxide aqueous solution is 1:8;
s2, adding sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water into the primary modified straw, and soaking for 12 hours at 50 ℃ to obtain the modified straw; wherein, the mass ratio of the straw to the sodium dodecyl benzene sulfonate to the sodium dodecyl sulfate is 1:2.0:1.5:22;
wherein, the preparation of the modified starch comprises the following steps:
step 1, dispersing starch in water, then adding hydrochloric acid aqueous solution with the mass concentration of 1%, and reacting for 5 hours at 55 ℃ to obtain primary modified starch aqueous emulsion; wherein the mass ratio of the starch to the water is 1:8, and the mass ratio of the starch to the hydrochloric acid aqueous solution is 1:0.04;
step 2, adding sodium persulfate into the primary modified starch aqueous emulsion, reacting for 3 hours at 70 ℃, and drying to obtain modified starch; wherein the mass ratio of the primary modified starch aqueous emulsion to the sodium persulfate is 1:0.15;
the embodiment also provides a preparation method of the urea-formaldehyde resin adhesive, which comprises the following steps:
(1) Weighing the components according to the mass ratio, regulating the pH value of the weighed formaldehyde aqueous solution to 7-7.5, then adding polyvinyl alcohol, preserving heat for 30min at 60 ℃, then adding 40% urea, and reacting for 60min at 90 ℃ to obtain a first reaction system;
(2) Adjusting the pH of the first reaction system to 4-5, then adding 40% urea, and reacting at 95 ℃ for 50min to obtain a second reaction system;
(3) Regulating the pH value of the second reaction system to 7-7.5, adding the rest urea, and reacting at 50 ℃ for 40min to obtain urea-formaldehyde resin;
(4) Uniformly mixing the urea-formaldehyde resin, the modified straw, the anti-aging agent, the modified starch and the 4-methylbenzenesulfonic acid at 100 ℃, then reacting for 50min at 50 ℃, and adding the curing agent to uniformly mix after the reaction is completed, thus obtaining the urea-formaldehyde resin adhesive.
Example 2
The embodiment provides a urea-formaldehyde resin adhesive, which comprises the following components in parts by weight: 250 parts of formaldehyde aqueous solution with the mass concentration of 37%, 160 parts of urea, 5 parts of polyvinyl alcohol, 10 parts of modified straw, 5 parts of anti-aging agent, 14 parts of curing agent, 10 parts of modified starch and 18 parts of 4-methylbenzenesulfonic acid;
wherein, the preparation of the modified straw comprises the following steps:
s1, adding 10% sodium hydroxide aqueous solution into straw with the particle size of 30nm, soaking for 5 hours at the temperature of 30 ℃, filtering, washing with water, and drying to obtain primary modified straw; wherein the mass ratio of the straw to the sodium hydroxide aqueous solution is 1:10;
s2, adding sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water into the primary modified straw, and soaking for 18 hours at 60 ℃ to obtain the modified straw; wherein, the mass ratio of the straw to the sodium dodecyl benzene sulfonate to the sodium dodecyl sulfate is 1:1.8:1.3:26;
wherein, the preparation of the modified starch comprises the following steps:
step 1, dispersing starch in water, then adding hydrochloric acid aqueous solution with the mass concentration of 3%, and reacting for 8 hours at 50 ℃ to obtain primary modified starch aqueous emulsion; wherein the mass ratio of the starch to the water is 1:10, and the mass ratio of the starch to the hydrochloric acid aqueous solution is 1:0.07;
step 2, adding sodium persulfate into the primary modified starch aqueous emulsion, reacting for 5 hours at 60 ℃, and drying to obtain modified starch; wherein the mass ratio of the primary modified starch aqueous emulsion to the sodium persulfate is 1:0.1;
the embodiment also provides a preparation method of the urea-formaldehyde resin adhesive, which comprises the following steps:
(1) Weighing the components according to the mass ratio, regulating the pH value of the weighed formaldehyde aqueous solution to 7-7.5, then adding polyvinyl alcohol, preserving heat for 20min at 50 ℃, then adding 30% urea, and reacting for 70min at 80 ℃ to obtain a first reaction system;
(2) Adjusting the pH of the first reaction system to 4-5, then adding 30% urea, and reacting at 100 ℃ for 80min to obtain a second reaction system;
(3) Regulating the pH value of the second reaction system to 7-7.5, adding the rest urea, and reacting at 58 ℃ for 40min to obtain urea-formaldehyde resin;
(4) Uniformly mixing the urea-formaldehyde resin, the modified straw, the anti-aging agent, the modified starch and the 4-methylbenzenesulfonic acid at 120 ℃, then reacting for 80min at 40 ℃, and adding the curing agent after the reaction is completed, and uniformly mixing to obtain the urea-formaldehyde resin adhesive.
Example 3
The embodiment provides a urea-formaldehyde resin adhesive, which comprises the following components in parts by weight: 220 parts of formaldehyde aqueous solution with the mass concentration of 37%, 150 parts of urea, 3 parts of polyvinyl alcohol, 9 parts of modified straw, 6 parts of anti-aging agent, 13 parts of curing agent, 12 parts of modified starch and 16 parts of 4-methylbenzenesulfonic acid;
wherein, the preparation of the modified straw comprises the following steps:
s1, adding a sodium hydroxide aqueous solution with the mass concentration of 11% into straw with the particle size of 20nm, soaking for 4.5 hours at 35 ℃, filtering, washing with water, and drying to obtain primary modified straw; wherein the mass ratio of the straw to the sodium hydroxide aqueous solution is 1:9;
s2, adding sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water into the primary modified straw, and soaking for 16 hours at 55 ℃ to obtain the modified straw; wherein, the mass ratio of the straw to the sodium dodecyl benzene sulfonate to the sodium dodecyl sulfate is 1:1.9:1.4:25;
wherein, the preparation of the modified starch comprises the following steps:
step 1, dispersing starch in water, then adding hydrochloric acid aqueous solution with mass concentration of 2%, and reacting for 6 hours at 55 ℃ to obtain primary modified starch aqueous emulsion; wherein the mass ratio of the starch to the water is 1:9, and the mass ratio of the starch to the hydrochloric acid aqueous solution is 1:0.05;
step 2, adding sodium persulfate into the primary modified starch aqueous emulsion, reacting for 4 hours at 63 ℃, and drying to obtain modified starch; wherein the mass ratio of the primary modified starch aqueous emulsion to the sodium persulfate is 1:0.13;
the embodiment also provides a preparation method of the urea-formaldehyde resin adhesive, which comprises the following steps:
(1) Weighing the components according to the mass ratio, regulating the pH value of the weighed formaldehyde aqueous solution to 7-7.5, then adding polyvinyl alcohol, preserving heat at 55 ℃ for 25min, then adding 35% urea, and reacting at 85 ℃ for 65min to obtain a first reaction system;
(2) Adjusting the pH of the first reaction system to 4-5, then adding 35% urea, and reacting at 98 ℃ for 60min to obtain a second reaction system;
(3) Regulating the pH value of the second reaction system to 7-7.5, adding the rest urea, and reacting at 55 ℃ for 35min to obtain urea-formaldehyde resin;
(4) Uniformly mixing the urea-formaldehyde resin, the modified straw, the anti-aging agent, the modified starch and the 4-methylbenzenesulfonic acid at 110 ℃, then reacting for 70min at 45 ℃, adding the curing agent after the reaction is completed, and uniformly mixing to obtain the urea-formaldehyde resin adhesive
Comparative example 1
The difference between this comparative example and example 1 is that: the sodium dodecylbenzenesulfonate was replaced with an equivalent amount of vinyltrimethoxysilane, and the remaining components and steps were the same as in example 1.
Comparative example 2
The difference between this comparative example and example 1 is that: the sodium persulfate was replaced with an equivalent amount of hydrogen peroxide, and the remaining components and steps were the same as in example 1.
The urea-formaldehyde resin adhesives provided in examples 1-3 and comparative examples 1-2 were tested, wherein the formaldehyde release was tested according to GBT 17657-2013, test for physicochemical Properties of Artificial Board and veneered Artificial Board;
the cementing strength is detected according to GB/T9846-2015 common plywood;
and (3) water resistance test: the cementing strength of the plate is measured after the plate is prepared into a sample strip according to the specification in GB/T9846-2015 and is soaked in hot water at 70 ℃ for 3 hours;
the specific detection results are shown in Table 1:
TABLE 1
| Detecting items | Formaldehyde emission (mg/L) | Cementing strength (MPa) | Cementing strength (MPa) after 3 hours of hot water soaking |
| Example 1 | 0.21 | 1.39 | 0.92 |
| Example 2 | 0.23 | 1.28 | 0.87 |
| Example 3 | 0.18 | 1.32 | 0.88 |
| Comparative example 1 | 0.42 | 0.82 | Plate glue cutting |
| Comparative example 2 | 0.63 | 0.69 | Plate glue cutting |
Table 1 shows that the formaldehyde release amount of the urea-formaldehyde resin adhesive provided by the embodiments 1-3 is as low as 0.18mg/L, the cementing strength can reach 1.39MPa, and the cementing strength after 3 hours of hot water soaking can also reach 0.92MPa; the invention takes urea-formaldehyde resin as a main component, and adds specific modified straw and modified starch, and three components form a three-dimensional reticular macromolecular crosslinked structure through crosslinking reaction, so that the cementing strength and the water resistance of the urea-formaldehyde resin adhesive are improved, the content of free formaldehyde can be further reduced, the problem of overhigh formaldehyde release in the prior art is fundamentally solved, the usability is good, the process is simple, the operation is easy, and the method is suitable for batch production.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, or alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The urea-formaldehyde resin adhesive is characterized by comprising the following components in parts by weight: 200-250 parts of formaldehyde aqueous solution, 143-160 parts of urea, 2-5 parts of polyvinyl alcohol, 7-10 parts of modified straw, 5-7 parts of anti-aging agent, 12-14 parts of curing agent, 10-15 parts of modified starch and 12-18 parts of 4-methylbenzenesulfonic acid;
wherein the mass concentration of the formaldehyde aqueous solution is 36.5% -37.5%;
the modified straw is modified by sodium hydroxide aqueous solution, sodium dodecyl benzene sulfonate and sodium dodecyl sulfate;
the modified starch is hydrochloric acid aqueous solution and sodium persulfate modified starch.
2. The urea-formaldehyde resin adhesive as set forth in claim 1, wherein the preparation of the modified straw comprises the steps of:
s1, adding a sodium hydroxide aqueous solution into straw, soaking at 30-40 ℃, filtering, washing with water, and drying to obtain primary modified straw;
s2, adding sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water into the primary modified straw, soaking at 50-60 ℃, filtering, washing with water, and drying to obtain the modified straw.
3. The urea-formaldehyde resin adhesive according to claim 2, wherein in S1, the particle size of the straw is 15nm-30nm; and/or
In S1, the mass concentration of the sodium hydroxide aqueous solution is 10% -12%; and/or
In S1, the mass ratio of the straw to the sodium hydroxide aqueous solution is 1 (8-10); and/or
In S1, the soaking time is 4-5 h.
4. The urea-formaldehyde resin adhesive as set forth in claim 2, wherein in S2, the mass ratio of the straw, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and water is 1 (1.8-2.0): (1.3-1.5): (22-26); and/or
And S2, soaking for 12-18 hours.
5. The urea-formaldehyde resin adhesive as set forth in claim 1, wherein the preparation of the modified starch comprises the steps of:
step 1, dispersing starch in water, then adding hydrochloric acid aqueous solution, and reacting at 50-55 ℃ to obtain primary modified starch aqueous emulsion;
and step 2, adding sodium persulfate into the primary modified starch aqueous emulsion, reacting at 60-70 ℃, and drying to obtain modified starch.
6. The urea-formaldehyde resin adhesive according to claim 5, wherein in step 1, the reaction time is 5h to 8h; and/or
In the step 1, the mass ratio of the starch to the water is 1 (8-10); and/or
In the step 1, the mass concentration of the hydrochloric acid aqueous solution is 1% -3%; and/or
In the step 1, the mass ratio of the starch to the aqueous solution of hydrochloric acid is 1 (0.04-0.07).
7. The urea-formaldehyde resin adhesive according to claim 5, wherein in step 2, the reaction time is 3h to 5h; and/or
In the step 2, the mass ratio of the primary modified starch aqueous emulsion to the sodium persulfate is 1 (0.1-0.15).
8. The urea-formaldehyde resin adhesive according to claim 1, wherein the anti-aging agent is an anti-aging agent AW; and/or
The curing agent is ammonium chloride.
9. A method for preparing the urea-formaldehyde resin adhesive as set forth in any one of claims 1 to 8, comprising the steps of:
step a, weighing the components according to the mass ratio, regulating the pH value of the weighed formaldehyde aqueous solution to 7-7.5, then adding polyvinyl alcohol, preserving heat at 50-60 ℃ for 20-30 min, then adding 30-40% of urea, and reacting at 80-90 ℃ for 60-70 min to obtain a first reaction system;
step b, regulating the pH value of the first reaction system to be 4-5, then adding 30% -40% of urea, and reacting at 95-100 ℃ for 50-80 min to obtain a second reaction system;
step c, regulating the pH value of the second reaction system to 7-7.5, then adding the rest urea, and reacting at 50-58 ℃ for 30-40 min to obtain urea-formaldehyde resin;
and d, uniformly mixing the urea-formaldehyde resin, the modified straw, the anti-aging agent, the modified starch and the 4-methylbenzenesulfonic acid at the temperature of 100-120 ℃, then reacting at the temperature of 40-50 ℃, and adding a curing agent after the reaction is completed, and uniformly mixing to obtain the urea-formaldehyde resin adhesive.
10. The method for preparing urea-formaldehyde resin adhesive according to claim 9, wherein in the step d, the reaction time is 50min-80min.
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| CN1621477A (en) * | 2004-10-18 | 2005-06-01 | 俞锋 | Urea-formaldehyde glue with low content of free aldehyde and its preparing method |
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| CN113773775A (en) * | 2021-11-11 | 2021-12-10 | 山东永创材料科技有限公司 | Preparation method of phenolic resin adhesive for wood |
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| CN1621477A (en) * | 2004-10-18 | 2005-06-01 | 俞锋 | Urea-formaldehyde glue with low content of free aldehyde and its preparing method |
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