A method of producing a molded tray and a primer composition

Abstract

This invention provides a method for producing molded pallets and a primary tack composition. The method includes the following steps: atomizing and spraying an isocyanate adhesive and a primary tack composition separately onto a plant-based pulverized material for atomized mixing; spreading the raw material evenly on a mold coated with a release agent; and hot-pressing under high temperature and pressure; wherein the primary tack composition is a mixture obtained by the condensation reaction of ammonia and excess ethylene oxide. This method solves the problem of perforation at the feet of molded pallets, reduces the defect rate, and lowers the overall production cost.

Description

Technical Field

[0001] This invention belongs to the field of molded pallets, and specifically relates to a method for producing molded pallets and an initial tack composition. Background Technology

[0002] Pallets, as an important carrier in logistics, are the basic unit of modern logistics transportation. As a new type of pallet, wooden molded pallets are gradually emerging in the industry. In particular, the introduction of isocyanate adhesives has solved the drawbacks of traditional molded pallets, giving them advantages such as waterproofing, high strength, and weather resistance.

[0003] CN115595112A describes a polyurethane adhesive prepared by modifying MDI with a combination of special polyether polyols and special compounds, and its application in the production of molded pallets, achieving high production efficiency and pallet mechanical strength. CN117700934A describes a composite pallet produced by molding waste wind turbine blades and waste wood with modified MDI adhesive, resulting in a dynamic load capacity of ≥2.7 tons and a static load capacity of 10-15 tons. CN114058311A discloses a modified isocyanate adhesive and its preparation method. By modifying isocyanate with benzene-ring-containing siloxanes and polyethylene glycol monomethyl ether, the molecular chain acquires excellent flexibility, effectively improving hydrophilicity, initial tack, and release properties. However, while this method improves initial tack, it still cannot completely solve the problem of pallet foot perforation caused by low initial tack.

[0004] Ethanolamine derivatives are low-molecular-weight polyether polyols, primarily produced through the ring-opening polymerization of triethanolamine and ethylene oxide. CN115160973A provides a curing agent composition that can rapidly cure adhesives, improve production efficiency, reduce hot-pressing time, and effectively solve problems such as weak edges, softness, and dark delamination in formaldehyde-free engineered wood panels. However, this curing agent composition mainly involves synthesizing triethanolamine derivatives through a polyether process using triethanolamine as an initiator, followed by component mixing and formulation. This method is costly and complex, hindering large-scale application. Furthermore, the synthesis of triethanolamine derivatives utilizes high-temperature and high-pressure methods, resulting in a complex process and a narrow molecular weight distribution of the produced product, making it unsuitable for pallet use.

[0005] Since the 1960s, selective processes for synthesizing ethanolamines have been developed to increase the yield of monoethanolamine, diethanolamine, and triethanolamine. However, no reports have been found on the development of processes using triethanolamine derivatives as the main products.

[0006] In summary, the problem of low initial tack between MDI adhesive and wood still exists in this field, which leads to perforation of molded pallet feet and high product defect rate. Summary of the Invention

[0007] One of the objectives of this invention is to provide a method for preparing a molded tray, which solves the problem of perforation at the feet of the molded tray, reduces the defect rate, and lowers the overall production cost.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a molded tray, the method comprising the following steps:

[0010] S1: The isocyanate adhesive and primary tack composition are respectively atomized and sprayed onto the plant-based crushed material for atomized mixing;

[0011] S2: Spread the raw material of S1 evenly on the mold coated with release agent, and hot press it under high temperature and high pressure to form it;

[0012] The initial tackifier composition described in S1 is a mixture obtained by the condensation reaction of ammonia and excess ethylene oxide.

[0013] In this invention, the initial tackifier composition and MDI are first added to the wood composition simultaneously during the S1 atomization sizing stage. During the high-temperature mold application process in the S3 hot-pressing stage, the hydroxyl groups of the initial tackifier react rapidly with the NCO- groups of the MDI, resulting in high initial tack on the wood and improving the perforation phenomenon at the pallet corners. This is mainly manifested in two aspects:

[0014] The polymerization reaction of broadly distributed triethanolamine derivatives with MDI forms a large cross-linked three-dimensional network on the wood surface, ensuring the initial tackiness of the wood. Due to the wide molecular weight distribution of the triethanolamine derivatives, the distribution of high, medium, and low molecular weights constructs prepolymers of different gradients on the wood surface, forming initial tackiness. This gradient prepolymer can ensure both the initial tackiness of the wood and achieve high final molding strength.

[0015] Small molecule compounds, primarily monoethanolamine, diethanolamine, and triethanolamine, penetrate the wood interior and react with MDI to form initial adhesion between the wood interfaces. These low molecular weight compounds react with MDI within the microporous channels of the wood structure, strengthening the adhesion between wood interfaces. Simultaneously, the high specific gravity of these small molecules (1.2 g / cm³) further enhances the adhesion between the wood interfaces. 3 The compound increases the bulk density of the pallet corner lumber, further increasing the strength of the pallet corner and improving perforation.

[0016] In this invention, the general structural formula of the triethanolamine derivative is shown below:

[0017]

[0018] Where a, b, and c are all integers between 0 and 10, and at least one of a, b, and c is not 0.

[0019] In one embodiment of the present invention, the initial tack composition S1 comprises a triethanolamine derivative, monoethanolamine, diethanolamine, and triethanolamine; wherein, the triethanolamine derivative is a compound formed by the further reaction of excess ethylene oxide with monoethanolamine, diethanolamine, and triethanolamine produced during the reaction of ammonia and ethylene oxide; preferably, the mass fraction of the triethanolamine derivative in the initial tack composition is 51%-99%, and the mass fraction of the sum of monoethanolamine, diethanolamine, and triethanolamine is 1%-49%; preferably, the polydispersity index d of the molecular weight distribution of the triethanolamine derivative in the initial tack composition is 1.3-4.0.

[0020] The polydispersity index d is the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mv), which can be determined by gel permeation chromatography, a method known in the industry.

[0021] The method for determining the polydispersity index of triethanolamine derivatives according to the present invention uses a gel permeation chromatography (GPC) instrument. A tetrahydrofuran solution (1.5 mg / ml) of the initial binder composition is injected into a high-pressure pump and fed into the chromatographic column at a rate of 1 ml / min for separation. The flow time and flow volume are collected using the instrument's detector to obtain a sample chromatogram. By subtracting the curves for monoethanolamine, diethanolamine, and triethanolamine from the chromatogram and correction curves, and independently integrating only the triethanolamine derivative, the Mw and Mv of the triethanolamine derivative are calculated. The polydispersity index d is then calculated using the following formula:

[0022] d = Mw / Mv;

[0023] In the above method, the proportions between each component can be calculated by integrating monoethanolamine, diethanolamine, triethanolamine, and triethanolamine derivatives individually.

[0024] In one embodiment of the present invention, the preparation method of the primary tackifier composition in S1 is as follows: ammonia water reacts with excess ethylene oxide to generate a mixture containing monoethanolamine, diethanolamine, triethanolamine, and triethanolamine derivatives, and the primary tackifier composition is obtained after deammoniation and dehydration; preferably, the molar ratio of ammonia water to ethylene oxide is (0.01-0.5):1; preferably, the concentration of ammonia water is 20-40 wt%; preferably, the reaction temperature is 25-70°C.

[0025] In one embodiment of the present invention, the plant-based pulverized material in S1 is one or more of wood, straw, and bamboo pulverized materials; preferably, the moisture content of the plant-based pulverized material is 5-20 wt%.

[0026] In one embodiment of the present invention, the amount of the primary tackifier composition added in S1 is 0.1-5 wt% of the plant-based pulverized material.

[0027] In one embodiment of the present invention, the temperature in S2 is 130-170°C, the pressure is 15-25 MPa, and the pressure holding time is 50-120 seconds.

[0028] Another object of the present invention is to provide a molded tray.

[0029] A molded pallet, wherein the pallet is prepared by the above-described preparation method, and the plant-based crushed material of the pallet is one or more of wood, straw, and bamboo crushed materials.

[0030] Another object of the present invention is to provide an initial tack composition.

[0031] A primary tack composition, wherein the composition is the composition prepared by the above-described method, the primary tack composition comprising a triethanolamine derivative, monoethanolamine, diethanolamine, and triethanolamine; wherein the triethanolamine derivative is a compound formed by the further reaction of excess ethylene oxide with monoethanolamine, diethanolamine, and triethanolamine produced during the reaction of ammonia and ethylene oxide; preferably, the mass fraction of the triethanolamine derivative in the primary tack composition is 51%-99%, and the mass fraction of the sum of monoethanolamine, diethanolamine, and triethanolamine is 1%-49%; preferably, the polydispersity index d of the molecular weight distribution of the triethanolamine derivative in the primary tack composition is 1.3-4.0.

[0032] Another object of the present invention is to provide a method for preparing an initial tack composition.

[0033] A method for preparing a primary tackifier composition, wherein the composition is the composition used in the above-mentioned preparation method, the method for preparing the primary tackifier composition is as follows: ammonia water reacts with excess ethylene oxide to generate a mixture containing monoethanolamine, diethanolamine, triethanolamine, and triethanolamine derivatives, and the mixture is then subjected to deammoniation and dehydration to obtain the primary tackifier composition; preferably, the molar ratio of ammonia water to ethylene oxide is (0.01-0.5):1; preferably, the concentration of ammonia water is 20-40 wt%; preferably, the reaction temperature is 25-70℃.

[0034] Another object of the present invention is to provide a use of an initial tack composition.

[0035] Use of an initial tack composition, wherein the composition is the composition used in the above-described preparation method, the composition being used in the preparation of articles from plant-based pulverized materials, preferably for the preparation of molded trays, and more preferably for the preparation of molded trays requiring initial tack.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) By using an isocyanate adhesive and a primary tack composition, a solution is provided for improving the quality defects of perforated pallet feet in the production of molded pallets. With the use of this solution, the perforation problem of pallet feet is greatly improved, and the defect rate is reduced from the original 5% to a minimum of 0.1%.

[0038] (2) A low-cost, wide molecular weight distribution primary tack composition production solution is provided. By adjusting the molar ratio, a primary tack composition suitable for the molded pallet production process can be obtained in one step, reducing the complexity of the production process. Detailed Implementation

[0039] The embodiments of the present invention are further illustrated below. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0040] Raw materials involved:

[0041] Wood shreds: waste plywood and waste solid wood, purchased from Anhui Aidesen Environmental Protection Technology Co., Ltd.;

[0042] Crushed straw: Ordinary straw, purchased from Anhui Aidesen Environmental Protection Technology Co., Ltd.;

[0043] Bamboo powder: ordinary bamboo, purchased from Anhui Aidesen Environmental Protection Technology Co., Ltd.;

[0044] Isocyanate I: PMDI, WANNATE CW20, Wanhua Chemical Group Co., Ltd.;

[0045] Isocyanate II: Modified PMDI, WANNATE 9131FC, Wanhua Chemical Group Co., Ltd.;

[0046] Isocyanate III: WANNATE HDI, Wanhua Chemical Group Co., Ltd.;

[0047] Ammonia solution: 20% by mass, Shandong Qilin Chemical Co., Ltd.

[0048] Ammonia solution: 25% by mass, Shandong Qilin Chemical Co., Ltd.

[0049] Ammonia solution: 28% by mass, Shandong Qilin Chemical Co., Ltd.

[0050] Ammonia solution: 40% by mass, Shandong Qilin Chemical Co., Ltd.

[0051] Ethylene oxide: Wanhua Chemical Group Co., Ltd.;

[0052] Monoethanolamine: 100% by mass, Hubei Xianlin Chemical Co., Ltd.;

[0053] Diethanolamine: 100% by mass, Hubei Xianlin Chemical Co., Ltd.;

[0054] Triethanolamine: 100% by mass, Hubei Xianlin Chemical Co., Ltd.;

[0055] Release agent 1: Polyethylene wax type, HA-soft80, Jiangsu Haian Petrochemical Co., Ltd.;

[0056] Release agent 2: Silicone oil type, KC201G3, Wanhua Chemical Group Co., Ltd.;

[0057] Potassium hydroxide: Industrial grade, Shandong Zhijia Chemical Co., Ltd.;

[0058] Phosphoric acid: 85%, Shandong Zhijia Chemical Co., Ltd.;

[0059] Polyether adsorbent: Industrial grade magnesium silicate, Wuhan Jiyesheng Chemical Co., Ltd.;

[0060] The main experimental instruments used in the test in this embodiment are:

[0061] Pallet mechanical testing machine, PN-CT50KE, Hangzhou Pinxiang Technology Co., Ltd., is mainly used to test pallet forklift performance and concentrated load on the pallet surface;

[0062] The A1-7000H universal mechanical testing machine, manufactured by Dongguan High-speed Railway Testing Instruments Co., Ltd., is mainly used to test the internal bonding strength of the tray, the bending strength of the reinforcing ribs, and the compressive strength of the support legs.

[0063] The gel permeation chromatograph, Agilent 1290 Infinity II, Agilent Technologies (China) Co., Ltd., is mainly used to determine molecular weight, and then to determine the polydispersity index of triethanolamine derivatives and the proportion of each component in the initial tackifier composition.

[0064] The method for determining the polydispersity index (Mw) of triethanolamine derivatives involves gel permeation chromatography (GPC). A tetrahydrofuran solution (1.5 mg / ml) of the initial binder composition is injected into a high-pressure pump and fed into the chromatographic column at a rate of 1 ml / min for separation. Flow time and flow volume are collected using the instrument's detector to obtain the sample chromatogram. After subtracting the curves for monoethanolamine, diethanolamine, and triethanolamine from the chromatogram and correction curves, only the triethanolamine derivative is independently integrated to calculate its Mw and Mv. The polydispersity index (d) is then calculated using the following formula:

[0065] d = Mw / Mv;

[0066] In the above method, the proportions between each component can be calculated by integrating monoethanolamine, diethanolamine, triethanolamine, and triethanolamine derivatives individually.

[0067] Example 1

[0068] Preparation of the primary tackifier composition:

[0069] 1000 kg of ammonia water (25%) and ethylene oxide at a molar ratio of 0.01 were reacted in a tubular reactor at a reaction temperature of 25°C and a reaction pressure of 1 MPa to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 49%, the weight ratio of triethanolamine derivative was 51%, and the polydispersity index of the triethanolamine derivative was 1.3.

[0070] Manufacturing of molded trays:

[0071] S1: Under stirring, 0.9 kg of isocyanate I and 0.018 kg of primary tack composition were diluted 3 times with water and then sprayed onto 17.082 kg of wood pulverizer with 8% moisture content by atomization.

[0072] S2: Apply 10g of release agent 1 evenly to the mold using atomized spraying.

[0073] The raw materials for atomized adhesive mixing are placed on the mold, spread out, and then molded in one go using a press at a temperature of 130℃ and a pressure of 18Mpa for 70 seconds.

[0074] Example 2

[0075] Preparation of the primary tackifier composition:

[0076] 1000 kg of ammonia water (28%) and ethylene oxide at a molar ratio of 0.1 were reacted in a tubular reactor at a reaction temperature of 45°C and a reaction pressure of 5 MPa to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 28%, the weight ratio of triethanolamine derivative was 72%, and the molecular weight polydispersity index of the triethanolamine derivative was 1.9.

[0077] Manufacturing of molded trays:

[0078] S1: Under stirring conditions, 0.36 kg of isocyanate II and 0.036 kg of primary tackifier composition are respectively atomized and sprayed onto 17.604 kg of wood / straw (weight ratio 1:1) pulverized material with a moisture content of 10%.

[0079] S2: Apply 10g of release agent 1 evenly to the mold using atomized spraying.

[0080] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 150℃ and a pressure of 20Mpa for 50s.

[0081] Example 3

[0082] Preparation of the primary tackifier composition:

[0083] 1000 kg of ammonia water (20%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.2, at a reaction temperature of 25°C and a reaction pressure of 3 MPa, to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 110°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 31%, the weight ratio of triethanolamine derivative was 69%, and the polydispersity index of the triethanolamine derivative was 2.7.

[0084] Manufacturing of molded trays:

[0085] S1: Under stirring, 1.26 kg of isocyanate III and 0.594 kg of primary tack composition were diluted twice with water and then sprayed separately onto 16.146 kg of wood pulverizer with a moisture content of 20%.

[0086] S2: Apply 10g of release agent 2 evenly as atomized spray onto the mold.

[0087] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 145℃ and a pressure of 18Mpa for 90s.

[0088] Example 4

[0089] Preparation of the primary tackifier composition:

[0090] 1000 kg of ammonia water (40%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.25, at a reaction temperature of 40°C and a reaction pressure of 0.5 MPa, to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 45%, the weight ratio of triethanolamine derivative was 55%, and the polydispersity index of the triethanolamine derivative was 1.5.

[0091] Manufacturing of molded trays:

[0092] S1: Under stirring, 0.72 kg of isocyanate II and 0.09 kg of primary tack composition are diluted with water by 1:1 and then sprayed by atomization onto 17.19 kg of wood pulverizer with a moisture content of 15%.

[0093] S2: Apply 10g of release agent 2 evenly as atomized spray onto the mold.

[0094] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 150℃ and a pressure of 16Mpa for 80s.

[0095] Example 5

[0096] Preparation of the primary tackifier composition:

[0097] 1000 kg of ammonia water (25%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.08 at a reaction temperature of 55°C and a reaction pressure of 2 MPa to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 18%, the weight ratio of triethanolamine derivative was 82%, and the molecular weight polydispersity index of the triethanolamine derivative was 3.3.

[0098] Manufacturing of molded trays:

[0099] S1: Under stirring conditions, 0.54 kg of isocyanate I and 0.054 kg of primary tackifier composition are respectively atomized and sprayed onto 16.956 kg of wood pulverizer with a moisture content of 7%.

[0100] S2: Apply 10g of release agent 1 evenly to the mold using atomized spraying.

[0101] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 135℃ and a pressure of 22Mpa for 75s.

[0102] Example 6

[0103] Preparation of the primary tackifier composition:

[0104] 1000 kg of ammonia water (28%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.4, a reaction temperature of 70 °C and a reaction pressure of 0.1 MPa, to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120 °C, and then dehydrated and concentrated in an evaporation system at 120 °C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 21%, the weight ratio of triethanolamine derivative was 79%, and the polydispersity index of the triethanolamine derivative was 2.9.

[0105] Manufacturing of molded trays:

[0106] S1: Under stirring conditions, 0.72 kg of isocyanate I and 0.9 kg of primary tack composition are diluted 5 times with water and sprayed separately into 16.38 kg of wood and bamboo (weight ratio 1:1) pulverized material with a moisture content of 13%.

[0107] S2: Apply 10g of release agent 2 evenly as atomized spray onto the mold.

[0108] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 135℃ and a pressure of 25Mpa for 85s.

[0109] Example 7

[0110] Preparation of the primary tackifier composition:

[0111] 1000 kg of ammonia water (28%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.35, at a reaction temperature of 65°C and a reaction pressure of 2.5 MPa, to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 33%, the weight ratio of triethanolamine derivative was 67%, and the polydispersity index of the triethanolamine derivative was 4.0.

[0112] Manufacturing of molded trays:

[0113] S1: Under stirring conditions, 0.81 kg of isocyanate adhesive and 0.342 kg of primary tack composition are diluted 4 times with water and then sprayed by atomization onto 16.848 kg of wood, straw and bamboo (weight ratio 1:1:1) pulverized material with a moisture content of 17%.

[0114] S2: Apply 10g of release agent 1 evenly to the mold using atomized spraying.

[0115] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 170℃ and a pressure of 16Mpa for 90s.

[0116] Example 8

[0117] Preparation of the primary tackifier composition:

[0118] 1000 kg of ammonia water (25%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.42 at a reaction temperature of 40°C and a reaction pressure of 4 MPa to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 32%, the weight ratio of triethanolamine derivative was 68%, and the molecular weight polydispersity index of the triethanolamine derivative was 1.6.

[0119] Manufacturing of molded trays:

[0120] S1: Under stirring conditions, 1.8 kg of isocyanate adhesive and 0.162 kg of primary tack composition are diluted 2.5 times with water and then sprayed by atomization onto 16.038 kg of straw crushed material with an 11% moisture content.

[0121] S2: Apply 10g of release agent 2 evenly as atomized spray onto the mold.

[0122] The raw material mixed by atomization in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 155℃ and a pressure of 19Mpa for 120s.

[0123] Example 9

[0124] Preparation of the primary tackifier composition:

[0125] 1000 kg of ammonia water (20%) and ethylene oxide were reacted in a tubular reactor at a molar ratio of 0.5, at a reaction temperature of 35°C and a reaction pressure of 3.5 MPa, to produce a mixture containing monoethanolamine, diethanolamine, triethanolamine, and a triethanolamine derivative. The mixture was then deaminated in a deammoniation tower at 150 kPa and 120°C, and then dehydrated and concentrated in an evaporation system at 120°C to obtain the aforementioned primary tackifier composition, wherein the weight ratio of monoethanolamine, diethanolamine, and triethanolamine was 1%, the weight ratio of triethanolamine derivative was 99%, and the molecular weight distribution polydispersity index of the triethanolamine derivative was 3.2.

[0126] Manufacturing of molded trays:

[0127] S1: Under stirring conditions, 0.99 kg of isocyanate adhesive and 0.756 kg of primary tack composition are diluted 1.5 times with water and then sprayed onto 16.254 kg of bamboo pulverized material with a moisture content of 5% by atomization.

[0128] S2: Apply 10g of release agent 1 evenly to the mold using atomized spraying.

[0129] The wood raw material mixed with atomized glue in step S1 is placed on the mold, and after being flattened, it is molded in one go using a press at a temperature of 160℃ and a pressure of 15Mpa for 110s.

[0130] Comparative Example 1

[0131] The process conditions are basically the same as in Example 4, with the following differences:

[0132] No tackifier composition is used in step S1 of the molded tray manufacturing process.

[0133] Comparative Example 2

[0134] The process conditions are basically the same as in Example 4, with the following differences:

[0135] Isocyanate II is not used in step S1 of the molded tray manufacturing process.

[0136] The test results of the examples and comparative examples are shown in the table below.

[0137] Comparative Example 3

[0138] The triethanolamine derivatives are synthesized using the traditional polyether process.

[0139] The synthesis process of the triethanolamine derivative is as follows: a 50% aqueous solution of triethanolamine and potassium hydroxide is added to a reaction vessel, the temperature is raised to 130°C, and after vacuum dehydration for 2 hours, ethylene oxide is added. After the reaction is completed at 140°C, the temperature is lowered to 80°C, distilled water, phosphoric acid, and polyether adsorbent are added, the temperature is raised to 120°C, and after dehydration for 2 hours, the temperature is lowered to 80°C and the product is discharged.

[0140] Components Triethanolamine potassium hydroxide Ethylene oxide distilled water Phosphoric acid Polyether adsorbent weight ratio 1 0.058 8 1.3 0.13 0.26

[0141] The obtained triethanolamine derivative was formulated according to the proportions of the initial tackifier composition in Example 4, namely: monoethanolamine, diethanolamine, triethanolamine in a weight ratio of 45%, and triethanolamine derivative in a weight ratio of 55%, with a polydispersity index of 1.1 for the molecular weight distribution of the triethanolamine derivative.

[0142] The production process of the molded tray is the same as in Example 4.

[0143] Comparative Example 4

[0144] The triethanolamine derivative was synthesized using a traditional polyether process, but the difference from the comparative example lies in the different ratios of monoethanolamine, diethanolamine, triethanolamine, and the triethanolamine derivative.

[0145] The obtained triethanolamine derivative was formulated according to the proportions of the initial tackifier composition in Example 4, namely: 70% by weight of monoethanolamine, diethanolamine, and triethanolamine, and 30% by weight of triethanolamine derivative, with a polydispersity index of 1.1 for the molecular weight distribution of the triethanolamine derivative.

[0146] The production process of the molded tray is the same as in Example 4.

[0147]

[0148] The above performance tests were conducted in accordance with the standard GB / T 41231-2021 "General Technical Conditions for Bamboo and Wood Shavings Molded Pallets".

[0149] Based on the above examples and comparative examples, the use of a primary tackifier process and the addition of a broadly distributed triethanolamine derivative primary tackifier composition can significantly reduce the defect rate compared to comparative documents 1-4, from 5% in comparative example 1 without using the primary tackifier to 0.1-1.5%.

[0150] Comparing Examples 1-9 with Comparative Example 2, it can be seen that without the use of isocyanate adhesive, the primary tack composition alone cannot be molded, indicating that the primary tack composition needs the cooperation of isocyanate adhesive to function.

[0151] Comparing Examples 1-9 with Comparative Example 3, it can be seen that the triethanolamine derivative (molecular weight distribution polydispersity index 1.1) produced using the conventional polyether process, with the same mass ratio of each component (as with the wide molecular weight distribution triethanolamine derivative of the present invention), only slightly reduced the defect rate and could not achieve the effect described in the examples.

[0152] As can be seen from the comparison between Examples 1-9 and Comparative Example 4, the triethanolamine derivative (molecular weight distribution polydispersity index 1.1) produced using the conventional polyether process could not significantly improve the perforation problem of the tray feet in the experiment of adjusting the mass ratio of the constituent substances, and could not achieve the effect of reducing the defect rate described in the examples.

[0153] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a molded tray, characterized in that, The method includes the following steps: S1: The isocyanate adhesive and primary tack composition are respectively atomized and sprayed onto the plant-based crushed material for atomized mixing; S2: Spread the raw material of S1 evenly on the mold coated with release agent, and hot press it under high temperature and high pressure to form it; The initial tackifier composition described in S1 is a mixture obtained by the condensation reaction of ammonia and excess ethylene oxide.

2. The method according to claim 1, characterized in that, The initial tack composition of S1 contains triethanolamine derivatives, monoethanolamine, diethanolamine, and triethanolamine; The triethanolamine derivative is a compound formed by the reaction of ammonia and ethylene oxide, in which excess ethylene oxide reacts with monoethanolamine, diethanolamine and triethanolamine produced in the reaction. Preferably, the mass fraction of the triethanolamine derivative in the primary tackifier composition is 51%-99%, and the mass fraction of the sum of monoethanolamine, diethanolamine, and triethanolamine is 1%-49%. Preferably, the triethanolamine derivative in the primary tackifier composition has a polydispersity index d of 1.3-4.

0.

3. The method according to claim 1 or 2, characterized in that, The preparation method of the primary tackifier composition described in S1 is as follows: ammonia water reacts with excess ethylene oxide to generate a mixture containing monoethanolamine, diethanolamine, triethanolamine, and triethanolamine derivatives, and the primary tackifier composition is obtained after deammoniation and dehydration. Preferably, the molar ratio of ammonia to ethylene oxide is (0.01-0.5):1; Preferably, the concentration of ammonia water is 20-40 wt%; Preferably, the reaction is carried out at a temperature of 25-70°C.

4. The method according to any one of claims 1-3, characterized in that, The plant-based pulverized material in S1 is one or more of wood, straw, and bamboo pulverized materials; Preferably, the moisture content of the plant-based pulverized material is 5-20 wt%. And / or, the amount of the primary tackifier composition added in S1 is 0.1-5 wt% of the plant-based pulverized material; And / or, the amount of isocyanate adhesive in S1 is 2%-10% of the plant-based pulverized material, preferably 3%-5%.

5. The method according to any one of claims 1-4, characterized in that, The temperature in S2 is 130-170℃, the pressure is 15-25Mpa, and the pressure holding time is 50-120s.

6. A molded tray, wherein the tray is prepared by the preparation method according to any one of claims 1-5, and the plant-based crushed material of the tray is one or more of wood, straw, and bamboo crushed materials.

7. A primary tack composition, said composition being the composition used in the preparation method according to any one of claims 1-5, characterized in that, The primary tack composition contains triethanolamine derivatives, monoethanolamine, diethanolamine, and triethanolamine; The triethanolamine derivative is a compound formed by the reaction of ammonia and ethylene oxide, in which excess ethylene oxide reacts with monoethanolamine, diethanolamine and triethanolamine produced in the reaction. Preferably, the mass fraction of the triethanolamine derivative in the primary tackifier composition is 51%-99%, and the mass fraction of the sum of monoethanolamine, diethanolamine, and triethanolamine is 1%-49%. Preferably, the triethanolamine derivative in the primary tackifier composition has a polydispersity index d of 1.3-4.

0.

8. A method for preparing an initial tack composition, wherein the composition is the composition used in the preparation method according to any one of claims 1-5, characterized in that, The preparation method of the primary tackifier composition is as follows: ammonia water reacts with excess ethylene oxide to generate a mixture containing monoethanolamine, diethanolamine, triethanolamine and triethanolamine derivatives, and the primary tackifier composition is obtained after deammoniation and dehydration. Preferably, the molar ratio of ammonia to ethylene oxide is (0.01-0.5):1; Preferably, the concentration of ammonia water is 20-40 wt%; Preferably, the reaction temperature is 25-70℃.

9. Use of an initial tack composition, wherein the composition is the composition used in the preparation method according to any one of claims 1-5, the composition being used in the preparation of articles from plant-based pulverized materials, preferably for the preparation of molded trays, and more preferably for the preparation of molded trays requiring initial tack.

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