Formaldehyde-free environment-friendly adhesive, formaldehyde-free environment-friendly shaving board and preparation method of formaldehyde-free environment-friendly shaving board

Abstract

The invention relates to a formaldehyde-free environment-friendly adhesive, a formaldehyde-free environment-friendly shaving board and a preparation method of the formaldehyde-free environment-friendly shaving board, and the formaldehyde-free environment-friendly adhesive comprises the following components in parts by weight: 85-90 parts of glycosyl resin composition main glue and 10-15 parts of a curing agent, the preparation method of the glycosyl resin composition main glue comprises the following steps: preparing the following raw materials in parts by weight: 30-40 parts of cane sugar, 10-15 parts of urea, 50-60 parts of water, 2-3 parts of sodium hydroxide, 2-5 parts of tannin, 0.2-0.5 part of a silane coupling agent and 0.1-0.2 part of gas-phase nano silicon dioxide; the preparation process comprises the following steps: adding water into a reactor, then adding cane sugar, urea and tannin, uniformly stirring, heating to 50 DEG C, adding sodium hydroxide after the materials are completely stirred and dissolved, heating to 90-95 DEG C, reacting for 3 hours, cooling to 60 DEG C, adjusting the pH value to 5.5-6.5, adding a silane coupling agent, adding gas-phase nano silicon dioxide, keeping the temperature for 1 hour, cooling and discharging for later use; and the curing agent is liquid polymerized MDI.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial board, in particular to a formaldehyde-free environment-friendly adhesive, a formaldehyde-free environment-friendly particle board and a preparation method of the formaldehyde-free environment-friendly particle board. BACKGROUND

[0002] The particle board on the market at present is mainly pressed by "three-aldehyde glue", and the main components of "three-aldehyde glue" all contain formaldehyde. The particle board pressed by "three-aldehyde glue" will release a certain amount of free formaldehyde, which is a primary carcinogen and is harmful to human body. In addition, the particle board pressed by "three-aldehyde glue" also has problems of poor strength and poor water resistance. The existing formaldehyde-free particle board technology does not have the problem of free formaldehyde release, but still has many defects so as to not completely replace the current "three-aldehyde glue". The invention patent application with the publication number CN114012857A adopts 10-12 parts of magnesium sulfate and 21-23 parts of magnesium oxide to prepare a magnesium-based inorganic adhesive, uniformly mixes 27-29 parts of dried shavings with the magnesium-based inorganic adhesive by using a glue mixer to prepare dried shavings containing the magnesium-based inorganic adhesive; adds isocyanate accounting for 2% to 7% of the mass of the dried pine shavings and magnesium chloride accounting for 1% to 5% of the mass of the magnesium-based inorganic adhesive into 40 parts of 7.5% PVA water-based glue to completely dissolve, and finally adds the above-mentioned water-based glue into the dried shavings containing the magnesium-based inorganic adhesive to mix uniformly, and then presses into a magnesium-based inorganic particle board. The invention does not release free formaldehyde and has a certain flame retardancy, but the amount of the magnesium-based inorganic adhesive is large, the hot-pressing temperature is high, and the appearance and hardness of the particle board are negatively affected. The invention patent application with the publication number CN114012857A adopts 12-18 parts of inert curing agent, 65-80 parts of unsaturated polyether polyol, 3.7-5.5 parts of chain extender, 7-9 parts of active diluent, 0.08-0.1 parts of initiator, 1-1.4 parts of emulsifier and 115-140 parts of water to synthesize two-component water-based polyurethane glue applied to particle board. The invention patent has excellent physical and chemical properties of the pressed particle board and does not release formaldehyde, but the glue component is complex, the reaction is not easy to control, toxic and volatile organic solvents are needed, and the synthesis cost is high. The invention patent application with the publication number CN106217533B adopts 50-88 parts of fructose-glucose syrup and 12-50 parts of modified poly MDI glue obtained by mixing to be applied to the current plywood, fiberboard and particle board, and the physical and chemical properties all meet the standard requirements, but the fiber needs to be activated before use to be glued, the viscosity of the glue is small, especially in the application of particle board, there is no initial adhesion, and the actual production is easy to cause the phenomenon of scattered blanks during the pre-pressing.

[0003] The existing defects of the formaldehyde-free shaving board adhesive are as follows: (1) the isocyanate adhesive requires high equipment and is easy to stick to the steel belt during production; (2) the synthetic components are complex, the reaction conditions are harsh, toxic and volatile organic solvents are used or the equipment requires high energy consumption; (3) a large amount of inorganic adhesive is used, which has a negative impact on the hardness and appearance of the shaving board; (4) the plant protein and starch formaldehyde-free adhesive is prone to mold and has high moisture absorption, and the adhesive viscosity is large, which is not conducive to sizing; (5) the fiber needs to be activated in advance, the initial adhesion is small, and the production process is prone to scattered blanks. SUMMARY

[0004] The present application provides a formaldehyde-free environmentally friendly adhesive, which comprises the following components by weight: The sugar-based resin composition main adhesive is 85-90 parts, and the curing agent is 10-15 parts.

[0005] The preparation method of the sugar-based resin composition main adhesive is as follows: the raw materials are proportioned by weight as follows: sucrose 30-40 parts, urea 10-15 parts, water 50-60 parts, sodium hydroxide 2-3 parts, tannin 2-5 parts, silane coupling agent 0.2-0.5 parts, and fumed nano-silicon dioxide 0.1-0.2 parts. The preparation process is as follows: water is added to the reactor, then sucrose, urea and tannin are stirred uniformly, the temperature is raised to 50°C, the material is stirred and dissolved completely, then sodium hydroxide is added, the temperature is raised to 90-95°C, and the reaction is carried out for 3 hours, then the temperature is lowered to 60°C, the PH value is adjusted to 5.5-6.5, the silane coupling agent is added, the fumed nano-silicon dioxide is added, and the temperature is kept for 1 hour, then the temperature is lowered and the material is discharged for standby use. The curing agent is liquid polymeric MDI.

[0006] Further, the sucrose is one or more than one mixture of granulated sugar, white granulated sugar, soft white sugar and brown sugar, the tannin is one or more than one mixture of condensed tannin and hydrolyzed tannin, and the silane coupling agent is one or more than one mixture of γ―(2,3-epoxypropoxy) propyl trimethoxysilane (KH-560) and 3-aminopropyl triethoxysilane (KH-550).

[0007] Further, the particle size of the fumed nano-silicon dioxide is 1-100 nm.

[0008] Further, the NCO content of the liquid polymeric MDI is 30-32.5%wt.

[0009] The present application also provides a formaldehyde-free environmentally friendly shaving board, which is prepared from shavings, adhesive and waterproof agent, wherein the adhesive is the formaldehyde-free environmentally friendly adhesive according to claim 1, and the use amount of the formaldehyde-free environmentally friendly adhesive is 100-120 kg / m³. The present application also provides a preparation method of the formaldehyde-free environmentally friendly shaving board, which comprises the following steps: S1, dry and screen out the surface layer fine material and the core layer coarse material, and mix each with formaldehyde-free environment-friendly adhesive and waterproof agent to obtain mixed adhesive shavings; S2, lay and pre-press the mixed adhesive shavings to obtain a formaldehyde-free shaving board blank; S3, after hot pressing, curing, cutting and sanding, the formaldehyde-free environment-friendly shaving board is obtained. Further, the shaving surface layer fine material is 3-15 mm long, 0.5-1.5 mm wide and 0.2-0.4 mm thick, and the shaving core layer coarse material is 15-45 mm long, 3-10 mm wide and 0.4-0.7 mm thick.

[0010] Further, the weight ratio of the shaving surface layer fine material and the core layer coarse material is 3:7-4:6, and the ratio of the adhesive for the surface layer and the adhesive for the core layer is 1:1.

[0011] Further, the waterproof agent is one or more than one mixture of emulsified paraffin, molten liquid paraffin or emulsified asphalt, and the amount used is 6-8 kg / m³.

[0012] Further, the water content of the surface layer fine material after applying the adhesive and the waterproof agent is controlled at 4-8%, and the water content of the core layer coarse material after applying the adhesive and the waterproof agent is controlled at 8-15%; When laying, the ratio of the upper surface layer fine material to the lower surface layer fine material is 1:1; The pre-pressing temperature in the step S2 is 25-40℃, the compression rate of the pre-pressed board blank is 1 / 2-1 / 3, and the pre-pressing pressure is 0.5-1.6 MPa; The hot pressing process in the step S3 is as follows: the temperature is 180-230℃, the first stage is to press to 5-6 MPa, the pressure is maintained for 7 s / mm, the second stage is to reduce the pressure to 2-3 MPa, the pressure is maintained for 5 s / mm, the third stage is to reduce the pressure to 1-2 MPa, the pressure is maintained for 5 s / mm, the fourth stage is to reduce the pressure to 0.2-0.5 MPa, the pressure is maintained for 3 s / mm, and the board is discharged after unloading.

[0013] Compared with the prior art, the advantages and positive effects of the present application are as follows: The adhesive used in the formaldehyde-free shaving board produced by the method of the present application has relatively low cost and good adhesive performance, and does not have special requirements for factory production equipment, which can seamlessly connect the production equipment of urea-formaldehyde glue and is friendly to the factory.

[0014] The formaldehyde emission of the formaldehyde-free shaving board produced by the method of the present application meets the ENF level requirements of GB / T 39600-2021. It is not easy to scatter the blank during production, and basically no release agent is needed. DETAILED DESCRIPTION Example 1

[0015] A preparation method of a formaldehyde-free environment-friendly shaving board is as follows: 1. Preparation of formaldehyde-free environmentally friendly adhesive: 1) Preparation of sugar-based resin composition main glue In the reactor, 50 parts of water was added, followed by 30 parts of white sugar, 10 parts of urea, 3 parts of larch tannin, and stirring was uniform. The temperature was raised to 50°C, and after the material was completely dissolved by stirring, 2 parts of sodium hydroxide was added. The temperature was raised to 95°C and reacted for 3 hours. The temperature was lowered to 60°C and the PH value was adjusted to 5.5. 0.2 parts of KH-560 silane coupling agent and 0.2 parts of silica with a particle size of 50 nm were added. The temperature was maintained for 1 hour, and the temperature was lowered to discharge the material. The sugar-based resin composition main glue was prepared.

[0016] 2) Preparation of formaldehyde-free environmentally friendly adhesive The raw materials were taken by weight parts: 85 parts of the sugar-based resin composition main glue prepared in this example, 15 parts of polymeric MDI (type PM200, produced by Wanhua, NCO content 30.0~32.0%), and mixed uniformly before use. The formaldehyde-free environmentally friendly adhesive was obtained.

[0017] 2. Preparation of formaldehyde-free environmentally friendly particle board Eucalyptus-judkinsia fibers were dried and sieved into 3~7mm long, 0.5~1.0mm wide, 0.2~0.4mm thick flake surface fine material; 15~30mm long, 3~9mm wide, 0.4~0.7mm thick flake core layer coarse material, with a moisture content of 1~3%.

[0018] 1.185kg of core layer coarse material was weighed, 185g of formaldehyde-free environmentally friendly adhesive prepared in this example and 5g of 55% paraffin emulsion were applied using a spray gun, and stirred uniformly to prepare core layer mixed glue flake; 0.79kg of surface layer fine material was weighed, 185g of formaldehyde-free environmentally friendly adhesive prepared in this example and 5g of 55% paraffin emulsion were applied using a spray gun, and stirred uniformly to prepare surface layer mixed glue flake. Then the surface layer mixed glue flake was evenly divided into upper and lower surface layers.

[0019] The mixed glue flake was laid in the mold according to the structure of lower surface layer-core layer-upper surface layer, and pre-pressed for 3 minutes at room temperature. The mold was removed, and the formaldehyde-free particle board blank was prepared. The blank was placed in a hot press, and a 2.5cm thickness gauge was used for hot pressing. The hot pressing parameters were set as follows: the first stage temperature was 210±2°C, the pressure was 5~6MPa, and the time was 3 minutes; the second stage temperature was 190±2°C, the pressure was 2~3MPa, and the time was 2 minutes; the third stage temperature was 180±2°C, the pressure was 1~2MPa, and the time was 2 minutes; the fourth stage temperature was 180±2°C, the pressure was 0.2~0.5MPa, and the time was 1 minute. After cooling, it was placed at room temperature for 10 days to obtain the formaldehyde-free environmentally friendly particle board. Example 2

[0020] A preparation method of an aldehyde-free environmentally friendly particle board is as follows: 1. Preparation of aldehyde-free environmentally friendly adhesive: 1) Preparation of sugar-based resin composition main glue In the reactor, 55 parts of water, then 40 parts of brown sugar, 15 parts of urea, 4 parts of black ash tree tannin were added, and stirred uniformly. After the material was completely dissolved by heating to 50℃, 3 parts of sodium hydroxide was added, and the temperature was raised to 95℃ for 3 hours. After the temperature was lowered to 60℃, the PH value was adjusted to 6.0, 0.2 parts of KH-550 silane coupling agent and 0.2 parts of silica with a particle size of 80 nm were added, and the temperature was kept for 1 hour. After the temperature was lowered, the material was discharged, and the sugar-based resin composition main glue was prepared.

[0021] 2) Preparation of aldehyde-free environmentally friendly adhesive The raw materials were taken by weight parts: 90 parts of the sugar-based resin composition main glue prepared in this example, 10 parts of polymeric MDI (type M200, produced by Mitsui, NCO content 30.5~32.0%), were mixed uniformly before use, and the aldehyde-free environmentally friendly adhesive was obtained.

[0022] 2. Preparation of aldehyde-free environmentally friendly particle board Eucalyptus-jatamansi fibers were dried and screened to obtain long 5~10mm, wide 0.5~1.0mm, thick 0.2~0.4mm flake surface layer fine material; long 20~35mm, wide 3~10mm, thick 0.4~0.7mm flake core layer coarse material, with a moisture content of 1~3%.

[0023] 0.77kg of core layer coarse material was weighed, 121g of the aldehyde-free environmentally friendly adhesive prepared in this example and 4g of 45% paraffin emulsion were applied using a spray gun, and the core layer mixed glue flake was prepared by stirring uniformly. Then 0.52kg of surface layer fine material was weighed, 121g of the aldehyde-free environmentally friendly adhesive prepared in this example and 4g of 45% paraffin emulsion were applied using a spray gun, and the surface layer mixed glue flake was prepared by stirring uniformly. Then the surface layer mixed glue flake was evenly divided into upper and lower surface layers.

[0024] The mixed glue flake was laid in the mold according to the structure of lower surface layer-core layer-upper surface layer, and pre-pressed for 3min at room temperature. After the mold was removed, the aldehyde-free particle board blank was prepared. Then the blank was placed in a hot press, and a 1.6cm thickness gauge was used for hot pressing. The hot pressing parameters were set as follows: the first stage temperature was 220±2℃, the pressure was 5~6MPa, the time was 2min; the second stage temperature was 180±2℃, the pressure was 2~3MPa, the time was 1min; the third stage temperature was 180±2℃, the pressure was 1~2MPa, the time was 1min; the fourth stage temperature was 180±2℃, the pressure was 0.2~0.5MPa, the time was 1min. After cooling, it was placed at room temperature for 10 days to obtain the aldehyde-free environmentally friendly particle board. Example 3

[0025] A preparation method of an aldehyde-free environmentally friendly particle board is as follows: 1. Preparation of aldehyde-free environmentally friendly adhesive: 1) Preparation of sugar-based resin composition main glue In the reactor, 55 parts of water, then 35 parts of icing sugar, 10 parts of urea, 4 parts of pine tannin were added, and stirred uniformly. After the material was completely dissolved by heating to 50℃, 3 parts of sodium hydroxide was added, and the temperature was raised to 95℃ for 3 hours. After the temperature was lowered to 60℃, the PH value was adjusted to 6.5, 0.2 parts of KH-560 silane coupling agent and 0.2 parts of silica with a particle size of 70 nm were added, and the temperature was kept for 1 hour. After the temperature was lowered, the material was discharged, and the sugar-based resin composition main glue was prepared.

[0026] 2) Preparation of aldehyde-free environmentally friendly adhesive The raw materials were taken by weight parts: 88 parts of the sugar-based resin composition main glue prepared in this example, 12 parts of polymeric MDI (type M20S, produced by BASF, NCO content 31.0%), were mixed uniformly before use, and the aldehyde-free environmentally friendly adhesive was obtained.

[0027] 2. Preparation of aldehyde-free environmentally friendly particle board Eucalyptus-jatamansi fibers were dried and screened to obtain flake surface layer fine material with a length of 5-15 mm, a width of 0.5-1.5 mm, and a thickness of 0.2-0.4 mm; flake core layer coarse material with a length of 20-45 mm, a width of 4-10 mm, and a thickness of 0.4-0.7 mm, with a moisture content of 1-3%.

[0028] 0.68 kg of core layer coarse material was weighed, 107 g of the aldehyde-free environmentally friendly adhesive prepared in this example and 6 g of 55% paraffin emulsion were applied using a spray gun, and the core layer mixed glue flake was prepared by stirring uniformly. Then 0.45 kg of surface layer fine material was weighed, 107 g of the aldehyde-free environmentally friendly adhesive prepared in this example and 6 g of 55% paraffin emulsion were applied using a spray gun, and the surface layer mixed glue flake was prepared by stirring uniformly. Then the surface layer mixed glue flake was evenly divided into upper and lower surface layers.

[0029] The mixed glue flake was laid in the mold according to the structure of lower surface layer-core layer-upper surface layer, and pre-pressed for 3 minutes at room temperature. After removing the mold, the aldehyde-free particle board blank was prepared. Then the board blank was placed in a hot press, and a 1.3 cm thickness gauge was used for hot pressing. The hot pressing parameters were set as follows: the first stage temperature was 220±2℃, the pressure was 5-6 MPa, the time was 2 minutes; the second stage temperature was 190±2℃, the pressure was 2-3 MPa, the time was 1 minute; the third stage temperature was 180±2℃, the pressure was 1-2 MPa, the time was 1 minute; the fourth stage temperature was 180±2℃, the pressure was 0.2-0.5 MPa, the time was 1 minute. After cooling, it was placed at room temperature for 10 days to obtain the aldehyde-free environmentally friendly particle board.

[0030] Then, the prepared formaldehyde-free environment-friendly shaving board was detected according to GB / T 4897-2015, and the specific test data are as follows: Example 1 Example 2 Example 3 Thickness mm 25.3 16.3 13.2 Density kg / m3 620 630 680 Modulus of rupture MPa 34.85 27.63 25.06 Elastic modulus MPa 2670 2480 2810 Internal bond strength MPa 0.50 0.45 0.45 Surface bond strength MPa 1.05 1.27 1.53 24h water absorption thickness expansion rate % 6.3 9.0 7.5 While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and spirit of the application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A formaldehyde-free, environmentally friendly adhesive, characterized in that, The components include the following parts by weight: The sugar-based resin composition contains 85-90 parts of the main adhesive and 10-15 parts of the curing agent. The preparation method of the main adhesive of the sugar-based resin composition is as follows: The raw materials are proportioned by weight as follows: 30-40 parts sucrose, 10-15 parts urea, 50-60 parts water, 2-3 parts sodium hydroxide, 2-5 parts tannin, 0.2-0.5 parts silane coupling agent, and 0.1-0.2 parts fumed nano silica. The preparation process is as follows: water is added to the reactor, followed by sucrose, urea, and tannin, and the mixture is stirred until homogeneous. The temperature is raised to 50°C. After the material is completely dissolved, sodium hydroxide is added, and the temperature is raised to 90-95°C for 3 hours. The temperature is then lowered to 60°C to adjust the pH value to 5.5-6.

5. A silane coupling agent is added, followed by fumed nano-silica. The mixture is kept at this temperature for 1 hour, and then cooled and discharged for later use. The curing agent is liquid polymeric MDI.

2. The formaldehyde-free environmentally friendly adhesive according to claim 1, characterized in that, The sucrose is one or more of rock sugar, granulated sugar, powdered sugar and brown sugar; the tannin is one or more of condensed tannin and hydrolyzed tannin; and the silane coupling agent is one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) and 3-aminopropyltriethoxysilane (KH-550).

3. The formaldehyde-free environmentally friendly adhesive according to claim 1, characterized in that, The particle size of the fumed silica nanoparticles is 1~100nm.

4. The formaldehyde-free environmentally friendly adhesive according to claim 1, characterized in that, The NCO content of the liquid polymerized MDI is 30~32.5%wt.

5. A formaldehyde-free, environmentally friendly particleboard, characterized in that, It is prepared from wood shavings, adhesive and waterproofing agent, wherein the adhesive is the formaldehyde-free environmentally friendly adhesive as described in claim 1, and the amount of the formaldehyde-free environmentally friendly adhesive is 100~120kg / m³.

6. A method for preparing formaldehyde-free environmentally friendly particleboard, characterized in that, Includes the following steps: S1. Dry and screen out the surface fine material and the core coarse material, and mix them with the formaldehyde-free environmentally friendly adhesive and waterproofing agent as described in claim 1 to obtain mixed adhesive wood shavings. S2. The mixed wood shavings are laid out and pre-pressed to obtain formaldehyde-free wood shavings blanks; S3. After hot pressing, curing, cutting and sanding the formaldehyde-free particleboard blank, formaldehyde-free environmentally friendly particleboard is obtained.

7. A method for preparing formaldehyde-free environmentally friendly particleboard according to claim 6, characterized in that, The fine surface layer of wood shavings is 3-15mm long, 0.5-1.5mm wide, and 0.2-0.4mm thick, while the coarse core layer of wood shavings is 15-45mm long, 3-10mm wide, and 0.4-0.7mm thick.

8. A method for preparing formaldehyde-free environmentally friendly particleboard according to claim 6, characterized in that, The weight ratio of fine surface wood chips to coarse core wood chips is 3:7 to 4:6, and the ratio of adhesive used in the surface layer to adhesive used in the core layer is 1:

1.

9. The method for preparing a formaldehyde-free environmentally friendly particleboard according to claim 6, characterized in that, The waterproofing agent is one or more of emulsified paraffin wax, molten liquid paraffin wax, or emulsified asphalt, and the dosage is 6~8 kg / m³.

10. A method for preparing formaldehyde-free environmentally friendly particleboard according to claim 6, characterized in that, The moisture content of the surface fine material after applying adhesive and waterproofing agent is controlled at 4-8%, and the moisture content of the core coarse material after applying adhesive and waterproofing agent is controlled at 8-15%. When paving, the ratio of the upper surface fine material to the lower surface fine material is 1:

1. In step S2, the pre-compression temperature is 25~40℃, the compression rate of the pre-compression slab is 1 / 2~1 / 3, and the pre-compression pressure is 0.5~1.6MPa. The hot pressing process in step S3 is as follows: temperature 180~230℃, first stage pressurization to 5~6MPa, holding pressure for 7s / mm, second stage depressurization to 2~3MPa, holding pressure for 5s / mm, third stage depressurization to 1~2MPa, holding pressure for 5s / mm, fourth stage depressurization to 0.2~0.5MPa, holding pressure for 3s / mm, and then depressurization and plate removal.