CN115595112B - Polyurethane adhesive, aldehyde-free addition mold pressing tray and preparation method thereof - Google Patents
Polyurethane adhesive, aldehyde-free addition mold pressing tray and preparation method thereof Download PDFInfo
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- CN115595112B CN115595112B CN202211587286.9A CN202211587286A CN115595112B CN 115595112 B CN115595112 B CN 115595112B CN 202211587286 A CN202211587286 A CN 202211587286A CN 115595112 B CN115595112 B CN 115595112B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
- C09J175/14—Polyurethanes having carbon-to-carbon unsaturated bonds
- C09J175/16—Polyurethanes having carbon-to-carbon unsaturated bonds having terminal carbon-to-carbon unsaturated bonds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/48—Polyethers
- C08G18/4833—Polyethers containing oxyethylene units
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/48—Polyethers
- C08G18/4833—Polyethers containing oxyethylene units
- C08G18/4837—Polyethers containing oxyethylene units and other oxyalkylene units
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/67—Unsaturated compounds having active hydrogen
- C08G18/671—Unsaturated compounds having only one group containing active hydrogen
- C08G18/6715—Unsaturated monofunctional alcohols or amines
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Abstract
The invention provides a polyurethane adhesive, a non-aldehyde-added molded tray and a preparation method thereof, and relates to the technical field of adhesives of molded trays. The polyurethane adhesive provided by the invention is particularly suitable for molded products, especially applied to a non-formaldehyde-added molded tray, and can obviously improve the production efficiency and the mechanical strength of the molded tray. The polyurethane adhesive is obtained by reacting reaction raw materials comprising a component I and a component II; wherein the component I comprises isocyanate; the component II comprises polyether polyol and a compound A; the polyether polyol is selected from one or more of polyoxyethylene polyol and polyoxyethylene-oxypropylene polyol; the compound A is selected from one or more of the following compounds with structural formula (I) and structural formula (II):
（I），
Description
Technical Field
The invention relates to the technical field of adhesives for molded products, in particular to a polyurethane adhesive particularly suitable for molded trays and application thereof.
Background
With the rapid development of the global packaging industry, the total scale of the world packaging industry reaches 10739 hundred million in 2020, and China replaces the United states and becomes the largest packaging market all over the world. The tray is used as an important packaging form and has irreplaceable function in modern logistics. At present, the requirement for cost reduction and efficiency improvement of the logistics industry is more urgent, and the mould pressing tray serving as a high-quality, low-price, high-efficiency and practical product can meet the requirements of carrying, storing and the like of wharfs, goods yards, warehouses, workshops, markets and the like.
The molded tray is a novel product which is formed by one-time compression molding at high temperature and high pressure after being crushed, cut into wood shavings, dried and applied with certain adhesive by taking wood, straw, peanut shell, cotton stalk and bamboo as raw materials. Compared with foreign large-scale manufacturers and relatively perfect wood shaving mold pressing tray systems, the wood shaving mold pressing tray system in China starts late and develops slowly. At present, domestic enterprises have the annual output of 20 ten thousand tablets or less except individual enterprises. The market has few and immature enterprises for preparing the mould pressing tray by using the polyurethane glue.
The invention patent with publication number CN102336292A uses a mixture of isocyanate and urea glue or a mixture of phenolic resin and melamine for preparing molded trays, but the glue still contains formaldehyde, and the formaldehyde is released continuously during long-term storage of the trays. The invention patent application with publication number CN114058311A discloses a modified isocyanate adhesive and a preparation method thereof, wherein siloxane containing benzene rings and polyethylene glycol monomethyl ether are used for modifying isocyanate, so that a molecular chain has good flexibility, and the hydrophilicity, initial adhesion and demolding performance are effectively improved. The invention patent with the publication number of CN105881693A discloses a die pressing tray and a manufacturing process thereof, wherein a main material and an auxiliary material are separately crushed into particles, an isocyanate adhesive is selected, and the formed tray has better strength and stability compared with the prior art.
However, there is no report in the prior art on how to improve the production efficiency and the pallet performance of the aldehyde-free addition molding pallet based on the polyurethane glue.
Disclosure of Invention
In view of the above, the present invention provides a polyurethane adhesive, a non-aldehyde addition molding tray and a preparation method thereof. The polyurethane adhesive provided by the invention is particularly suitable for molded products, especially applied to a non-formaldehyde-added molded tray, and can obviously improve the production efficiency and the mechanical strength of the molded tray.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides a polyurethane adhesive, which is obtained by reacting reaction raw materials comprising a component I and a component II;
wherein the component I comprises isocyanate; the component II comprises polyether polyol and a compound A;
the polyether polyol is selected from one or more of polyoxyethylene polyol and polyoxyethylene-propylene oxide polyol;
the compound A is selected from one or more of the following compounds with structural formula (I) and structural formula (II):
wherein n in the structural formula (I) and the structural formula (II) is an integer of 1-5 independently, for example, n is 1, 2, 3, 4 or 5.
The polyurethane adhesive prepared by the component I (including isocyanate) and the component II (including polyoxyethylene polyol and/or polyoxyethylene-propylene oxide polyol and a specific compound A) has good application effect when being applied to a preparation process of a molded product such as a molded tray, is beneficial to improving the production efficiency and the mechanical property of the product, can realize compression molding within relatively short pressure maintaining time, and can endow the product with higher bonding strength.
Preferably, compound a is preferably selected from one or more of the compounds of formula (II). Compared with the compound containing the structural formula (I), the compound containing the structural formula (II) in the component II has more outstanding performance on improving the production efficiency of the molded tray, is beneficial to improving the production efficiency of obtaining products with excellent mechanical properties, and can obviously shorten the pressure maintaining time required by the compression molding of the tray.
In the polyurethane adhesive of the present invention, the compound a in the component II is blended with a specific polyether polyol and an isocyanate, and a molded article, particularly a molded tray, excellent in mechanical properties can be obtained with high production efficiency, and in some embodiments, the mass content of the compound a in the component II may be 1ppm to 1%, for example, 1ppm, 5ppm, 10ppm, 50ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 0.5%, 1%, and the like, preferably 1 to 500ppm, for example, 1 to 100ppm and the like.
In a preferred embodiment, the sum of the amounts of the component I and the component II is 100 parts by mass:
the component I is used in an amount of 80 to 99 parts by mass, for example, 80, 82, 85, 87, 90, 92, 95, 97, 99 parts by mass, etc., preferably 85 to 95 parts by mass;
the component II is used in an amount of 1 to 20 parts by mass, for example, 1, 3, 5, 8, 10, 13, 15, 18, 20 parts by mass and the like, preferably 3 to 10 parts by mass.
The inventor finds that the polyurethane adhesive prepared by adopting the components I and II in the preferable mass ratio has better application effect when being applied to a preparation process of a molded product, and is beneficial to further remarkably improving the production efficiency and the mechanical property of the product. The pressure forming can be realized in relatively shorter pressure holding time, and the adhesive has good compatibility with substrate materials, particularly substrate materials based on herbaceous plants or woody plants (such as wood or bamboo), and is easy to realize higher bonding strength.
In the polyurethane adhesive of the present invention, the polyether polyol may be selected from the corresponding raw materials conventionally used in the art, and is not particularly limited, and preferably, the polyether polyol is selected from one or more of polyoxyethylene polyol, polyoxyethylene-oxypropylene polyol having a molecular weight Mn of 1000 to 5000g/mol and a functionality of 2 to 4, and preferably selected from one or more of polyoxyethylene polyol, polyoxyethylene-oxypropylene polyol having a molecular weight Mn of 3000 to 5000g/mol and a functionality of 2 to 4.
In the polyurethane adhesive of the present invention, the isocyanate may be selected from corresponding raw materials conventionally used in the art, and is not particularly limited, and preferably, the isocyanate has a functionality of not less than 2, and is preferably selected from one or more combinations of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), and polymethylene polyphenyl polyisocyanate. Wherein the polymethylene polyphenyl polyisocyanate is, for example, but not limited to, a polyisocyanate of the Wannate series of Wannate group, ltd, including any one or a combination of at least two of PM-100, PM-200, PM-400, PM-600, PM-700, CW20 and CW 30.
In the component II of the present invention, the compound A may be contained in the component II by adding it alone, or the component II of the present invention may be provided integrally with the polyether polyol starting material, for example, the component II of the present invention may be provided in the form of a polyether polyol previously containing a desired amount of the compound A. In a preferred embodiment, component II, however provided, is preferably present in an amount of from 1ppm to 1%, more preferably from 1 to 500ppm, based on the total mass of component II, of compound A. In particular applications, if desired, the amount of compound a in component II of the present invention can be determined by methods conventional in the art for determining the amount of compound a in component II, for example, by using a gas chromatography-mass spectrometer (GC-MS) according to methods conventional in such instruments. For example, the content of compound a in component II can be determined with reference to the following operations: placing 30mg of the component II in a glass tube, sealing, placing in a thermal desorption instrument of a gas chromatography-mass spectrometer (GC-MS), heating at 90 deg.C for 10 min, and performing content detection by automatic sample injection.
The invention also provides a preparation method of the polyurethane adhesive, which comprises the step of mixing and reacting the reaction raw materials to obtain the polyurethane adhesive.
Preferably, the reaction is carried out at 60-90 ℃, preferably 70-80 ℃, and the reaction time is preferably 1-4h, more preferably 1.5-2.5h; the stirring rate for stirring during the reaction is preferably 300 to 500rad/s, more preferably 300 to 400rad/s.
According to the polyurethane adhesive provided by the invention, firstly, isocyanate groups react with hydroxyl groups of polyoxyethylene polyol and/or polyoxyethylene-oxypropylene polyol to improve the compatibility of isocyanate and water, so that residual isocyanate can react with water under homogeneous phase, the reaction rate of the residual isocyanate and water in a base material in the subsequent hot pressing process of a molded product such as a molded tray is greatly improved, and the molding of the molded tray is facilitated. Secondly, introducing double bonds into a polyurethane adhesive system through the reaction of isocyanate groups and a compound A of a structural formula (I) and/or (II); because the common base material, especially the base material based on herbaceous plants and/or woody plants (such as wood or bamboo), has a large amount of lignin, cellulose (abundant double bonds) and the like, the compatibility with the base material can be effectively improved, and higher bonding strength is further facilitated to be formed; besides, the segment structure of the ether structure and the polyether polyol in the compound A has extreme compatibility; under the comprehensive action of the above aspects, a strong bonding effect can be realized in the preparation process of a molded product, particularly a molded tray, the production time (namely the pressure maintaining time) is reduced, the production efficiency is improved, and a product with good mechanical property is obtained.
The invention also provides the use of the polyurethane adhesive described above in moulded articles. The polyurethane adhesive is applied to the molded product, is beneficial to improving the preparation efficiency of the molded product, shortening the pressure maintaining time and obtaining a product with excellent mechanical property. Specifically, the molded article includes one or more of a molded panel (e.g., plywood, fiberboard, particle board, etc.) and a molded tray; the substrate material of the molded article may be conventional in the art, for example, the substrate material of the molded article may be, but is not limited to, one or more of wood shavings, boards, fibers, preferably including wood shavings, boards, fibers derived from herbaceous plants and woody plants, such as, in particular, one or more of wood shavings, wooden boards, wood fibers, bamboo shavings, bamboo boards, bamboo fibers, peanut shells, straws, cotton stalks, and the like; in some embodiments, the substrate material of the molded article comprises a material derived from agricultural and forestry residues. The meaning of the agricultural and forestry residues is well known in the art, and the agricultural and forestry residues comprise harvesting residues, lumber making residues, processing residues and the like; examples of felling residues include branches, twigs, treetops, bark, leaves, roots, canes, bushes and the like remaining during felling, examples of timber residues include timber truncations and the like, examples of processing residues include veneers, laths, wood bamboo truncations, sawdust, crushed veneers, wood cores, shavings, wood blocks, leftover bits and the like.
The invention also provides a mould pressing tray without aldehyde addition, and the adhesive used in the mould pressing tray is the polyurethane adhesive. The polyurethane adhesive is particularly suitable for being used in a mould pressing tray, can effectively improve the production efficiency, shorten the pressure maintaining time and obviously improve the mechanical property of the mould pressing tray. The substrate material of the molded tray may be conventional in the art, for example, including but not limited to one or more of wood shavings, boards, fibers, preferably including wood shavings, boards, fibers derived from herbaceous and woody plants, such as, in particular, one or more of wood shavings, wooden boards, wood fibers, bamboo shavings, bamboo boards, bamboo fibers, straw, peanut shells, cotton stalks; in some embodiments, the substrate material of the molded article comprises a material derived from agricultural residue.
Preferably, in the molded tray of the present invention, the amount of the polyurethane adhesive is 3% to 10% by mass of the base material, for example, 3%, 5%, 7%, 10%, etc. The polyurethane adhesive is applied according to the optimal dosage, so that the molded tray which gives consideration to the better production efficiency and the better performance can be obtained.
The present invention also provides a method for preparing the above aldehyde-free addition molded tray, comprising the steps of:
1) Controlling the water content of the substrate material to be 8-20wt%, such as 8%, 10%, 15%, 20%, etc.;
2) Applying the polyurethane adhesive to the substrate material; application means such as atomizing sizing or showering;
3) Applying a release agent on the moulds of the hot press, then placing the substrate material obtained in step 2) in the moulds of the hot press, and then hot-pressing to form the moulded tray. The release agent may be a material commonly used in the art, such as, but not limited to, polyethylene wax, silicone oil, and the like, and is applied in an amount to form a film layer of the release agent on the mold surface.
Specifically, the method can further comprise the following operation of taking the molded tray out of the hot press after the step 3) is finished, polishing the edge part, and cooling and ageing.
In a preferred embodiment, in step 3), the hot pressing is performed at a temperature of 120 ℃ to 200 ℃, a pressure holding pressure of 13 Mpa to 20Mpa, and a pressure holding time of 80s to 300s. The polyurethane adhesive can complete hot pressing in relatively shorter dwell time, thereby improving the production efficiency, and particularly, the dwell time can be shortened to 80s-250s, such as 80s-200s, for example, lower than 200s, such as 80s, 100s, 120s, 150s, 170s, 180s, 200s and the like.
In some embodiments, the resulting molded tray has a density of 800-1100kg/m 3 Preferably 900-1000 kg/m 3 。
The technical scheme provided by the invention has the following beneficial effects:
the polyurethane adhesive provided by the invention is prepared based on isocyanate, polyoxyethylene polyol and/or polyoxyethylene-propylene oxide polyol and a specific compound A, and is applied to a molded product, particularly a molded tray, so that the production efficiency and the mechanical property of the molded product are improved.
Detailed Description
In order to facilitate understanding of the present invention, the present invention will be further described with reference to examples. It should be understood that the following examples are only for better understanding of the present invention and are not intended to limit the present invention to the following examples.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "and/or" as may be used herein includes any and all combinations of one or more of the associated listed items.
The specific experimental procedures or conditions are not shown in the examples, and the procedures or conditions may be performed according to the procedures or conditions of the corresponding conventional experimental procedures in the art. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Some of the starting materials used in the following examples or comparative examples are illustrated below:
compound a1:
shanghai Mirui Biochemical technology Ltd
Compound a2:
jiangsu Haian petrochemical Co., ltd;
compound a3:
jiangsu Haian petrochemical Co., ltd;
compound a4:
hubei Shicheng chemical Co., ltd;
compound a5:
advanced Chemblocks, inc.;
compound a6:
advanced Chemblocks, inc.;
polyether polyol (1): WANOL C3185, polyoxyethylene polyol, wanhua chemical group, inc.;
polyether polyol (2): WANOL R2305, polyoxyethylene-oxypropylene polyol, wanhua chemical group, inc;
polyether polyol (3): WANOL C3110, polyoxyethylene-oxypropylene polyol, wanhua chemical group, inc.;
isocyanate I: WANNATE CW20, wanhua chemical group, inc;
isocyanate II: WANNATE PM200 and WANNATE MDI-100 1:1 (mass ratio) mixture, wanhua chemical group Ltd;
isocyanate III: WANNATE HDI, wanhua chemical group, inc.;
mold release agent 1: polyethylene wax type, HA-soft80, jiangsu Haian petrochemical Co., ltd.;
and (2) release agent: silicone oil type, KC201, wawa chemical group ltd.
The main experimental instruments used for the tests in the examples:
the tray mechanical testing machine, PN-CT50KE, hangzhou enjoying science and technology limited company, is mainly used for testing the tray fork lifting performance and the plate surface concentrated load;
A1-7000H universal mechanical testing machine, high-speed rail detection instrument (Dongguan) Co., ltd., mainly used for testing the internal bonding strength of a tray, the bending strength of a reinforcing rib and the compression strength of a supporting leg;
example 1:
preparing a polyurethane adhesive:
s1: in a 5L reactor equipped with a stirrer and a thermometer, 99 parts by mass of component I (which is isocyanate I) and 1 part by mass of component II (which is polyether polyol (1) and compound a 1) were charged, and the mass content of compound a1 in component II was 32 ppm.
S2: and opening stirring, setting the stirring speed to be 300 rad/s, reacting for 1h in an oil bath at the heating temperature of 90 ℃, cooling and discharging after the reaction is finished to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition molded tray:
and (4) SS1: preparing raw materials: the poplar wood shavings are obtained by chipping and slicing, and the moisture content of the shavings is controlled to be 12 wt% after drying.
And (4) SS2: sizing: the polyurethane adhesive is applied to the wood wool raw material by means of atomization sizing at a sizing amount of 10% (by mass of the wood wool).
And SS3: hot pressing: spraying a release agent 1 on each part of an upper die and a lower die of a hot press, after the release agent has no volatile matter and forms a film on the upper die and the lower die, placing the wood shavings applied with the polyurethane adhesive into the dies, paving the wood shavings and performing hot pressing at 174 ℃, wherein the pressure maintaining time is 150s, and the pressure maintaining pressure is 18 Mpa.
And (4) SS: and a post-treatment process: and taking the die pressing tray subjected to hot pressing and demolding out of the hot pressing machine, polishing the edge part, cooling and ageing.
Example 2:
preparing a polyurethane adhesive:
s1: in a 5L reactor equipped with a stirrer and a thermometer, 80 parts by mass of component I (which is isocyanate II), 20 parts by mass of component II (which is polyether polyol (2) and compound a 2), and the mass content of compound a2 in component II is 100ppm were added.
S2: and opening stirring, setting the stirring speed to be 400rad/s, reacting for 2.5h under the oil bath with the heating temperature of 60 ℃, cooling and discharging after the reaction is finished to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition mould pressing tray:
and (4) SS1: preparing raw materials: the pine wood shavings are obtained by chipping and slicing, and the moisture content of the shavings is controlled to be 20wt% after drying.
And (4) SS2: sizing: the polyurethane adhesive was applied to the wood shaving stock by spraying with a glue application amount of 7% (by mass of the wood shavings).
And (4) SS3: hot pressing: spraying a release agent 2 on each part of an upper die and a lower die of a hot press, placing wood shavings applied with polyurethane adhesives in the dies after the release agent has no volatile matters and forms films on the upper die and the lower die, paving the wood shavings and then carrying out hot pressing at 200 ℃, wherein the pressure maintaining time is 140s, and the pressure maintaining pressure is 14 Mpa.
And SS4: and a post-treatment process: and taking the die pressing tray subjected to hot pressing and demolding out of the hot pressing machine, polishing the edge part, cooling and ageing.
Example 3:
preparing a polyurethane adhesive:
s1: in a 5L reactor equipped with a stirrer and a thermometer, 85 parts by mass of component I (isocyanate II) and 15 parts by mass of component II (polyether polyol (3) and compound a 4) were charged, and the mass content of compound a4 in component II was 1%.
S2: and opening stirring, setting the stirring speed to be 300 rad/s, reacting for 1h in an oil bath at the heating temperature of 79 ℃, cooling after the reaction is finished, and discharging to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition molded tray:
and (4) SS1: preparing raw materials: slicing and slicing to obtain the bamboo raw material wood shavings, and controlling the water content of the wood shavings to be 10wt% after drying.
And SS2: sizing: the polyurethane adhesive was applied to the wood wool base by means of atomizing sizing at a sizing amount of 4% (by mass of the wood wool).
And (4) SS3: hot pressing: spraying a release agent 1 on each part of an upper die and a lower die of a hot press, after the release agent has no volatile matter and forms films on the upper die and the lower die, placing wood shavings applied with polyurethane adhesives in the dies, paving the wood shavings and then carrying out hot pressing at 143 ℃, wherein the pressure maintaining time is 100s, and the pressure maintaining pressure is 16 Mpa.
And SS4: and a post-treatment process: and taking the die pressing tray subjected to hot pressing and demolding out of the hot pressing machine, polishing the edge part, cooling and ageing.
Example 4:
preparing a polyurethane adhesive:
s1: 91 parts by mass of component I (isocyanate I) and 9 parts by mass of component II (polyether polyol (3) and compound a 5) are charged into a 5L reactor equipped with a stirrer and a thermometer, and the mass content of compound a5 in component II is 420 ppm.
S2: and opening stirring, setting the stirring speed to be 500rad/s, reacting for 1.5h under the oil bath with the heating temperature of 71 ℃, cooling and discharging after the reaction is finished to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition molded tray:
SS1: preparing raw materials: the raw material wood shavings of the peanut shells are obtained by chipping and slicing, and the water content of the wood shavings is controlled to be 15wt% after drying.
And (4) SS2: sizing: the polyurethane adhesive is applied to the wood shaving raw material by means of glue spraying in an amount of 5% (by mass of the wood shavings).
And (4) SS3: hot pressing: spraying a release agent 1 on each part of an upper die and a lower die of a hot press, after the release agent has no volatile matter and forms a film on the upper die and the lower die, placing the wood shavings applied with the polyurethane adhesive into the dies, paving the wood shavings and performing hot pressing at 196 ℃, wherein the pressure maintaining time is 90 s, and the pressure maintaining pressure is 13 Mpa.
And SS4: and a post-treatment process: and taking the die pressing tray subjected to hot pressing and demolding out of the hot pressing machine, polishing the edge part, cooling and ageing.
Example 5:
preparing a polyurethane adhesive:
s1: in a 5L reactor equipped with a stirrer and a thermometer, 95 parts by mass of component I (which is isocyanate II), 5 parts by mass of component II (which is polyether polyol (1) and compound a 6), and the mass content of compound a6 in component II is 1ppm were added.
S2: and opening stirring, setting the stirring speed to be 450 rad/s, reacting for 2h in an oil bath at the heating temperature of 78 ℃, cooling after the reaction is finished, and discharging to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition molded tray:
SS1: preparing raw materials: the poplar wood shavings are obtained by chipping and slicing, and the moisture content of the shavings is controlled to be 8wt% after drying.
And SS2: sizing: the polyurethane adhesive is applied to the wood wool raw material by means of atomizing sizing at a sizing amount of 3% (by mass of the wood wool).
And SS3: hot pressing: spraying a release agent 2 on each part of an upper die and a lower die of a hot press, after the release agent has no volatile matter and forms a film on the upper die and the lower die, placing the wood shavings applied with the polyurethane adhesive into the dies, paving the wood shavings and performing hot pressing at 164 ℃, wherein the pressure maintaining time is 80s, and the pressure maintaining pressure is 16 Mpa.
And (4) SS: and a post-treatment process: and taking the die pressing tray subjected to hot pressing and demolding out of the hot pressing machine, polishing the edge part, cooling and ageing.
Example 6:
preparing a polyurethane adhesive:
s1: in a 5L reactor equipped with a stirrer and a thermometer, 86 parts by mass of component I (which is isocyanate III), 14 parts by mass of component II (which is polyether polyol (1) and compound a 1), and the mass content of compound a1 in component II is 5000 ppm were added.
S2: and opening stirring, setting the stirring speed to be 350 rad/s, reacting for 1h in an oil bath at the heating temperature of 90 ℃, cooling after the reaction is finished, and discharging to obtain the polyurethane adhesive.
The prepared polyurethane adhesive is used for producing the die pressing tray without aldehyde addition.
Preparing a non-aldehyde addition molded tray:
SS1: preparing raw materials: the pine wood shavings are obtained by chipping and slicing, and the moisture content of the shavings is controlled to be 17wt% after drying.
And SS2: sizing: the polyurethane adhesive is applied to the wood wool raw material by means of atomization sizing at a sizing amount of 8% (by mass of the wood wool).
And (4) SS3: hot pressing: spraying a release agent 1 on each part of an upper die and a lower die of a hot press, after the release agent has no volatile matter and forms a film on the upper die and the lower die, placing the wood shavings applied with the polyurethane adhesive into the dies, paving the wood shavings and performing hot pressing at 120 ℃, wherein the pressure maintaining time is 160 s, and the pressure maintaining pressure is 20 Mpa.
And (4) SS: and a post-treatment process: and taking the mould pressing tray subjected to hot pressing and demoulding out of the hot press, polishing the edge part, cooling and ageing.
Comparative example 1:
the process conditions were substantially the same as those in example 4, except that:
compound a5 is not present in component II in step S1;
the holding pressure time in step SS3 was 250s.
Comparative example 2:
the process conditions were substantially the same as those of example 4, with the difference that:
no polyether polyol is used in step S1;
the pressure holding time in step SS3 was 300s.
Comparative example 3:
the process conditions were substantially the same as those of example 4, with the difference that:
no isocyanate is used in step S1;
the pressure holding time in step SS3 was 400 seconds.
Comparative example 4:
the process conditions were substantially the same as those in example 4, except that:
compound a3 is used instead of compound a5 in step S1;
the pressure holding time in step SS3 was 230s.
The test results of examples and comparative examples are shown in Table 1
The performance is tested according to the general technical conditions of the standard GB/T41231-2021 for the bamboo wood shaving compression molding pallet.
Compared with the comparative documents 1 and 2, the polyurethane adhesive prepared by the embodiment and the comparative example based on the mutual combination and reaction of the isocyanate, the polyether polyol and the compound A can greatly shorten the pressure maintaining time required by the hot press molding of the tray, greatly improve the production efficiency, and obviously improve the mechanical property of the molded tray.
Comparing examples 1-6 with comparative examples 1-3, it can be seen that the internal bonding strength of the tray prepared in the examples is 1.4MPa-2.0MPa, the bending resistance of the reinforcing rib is 450kg-627kg, the compressive strength of the supporting leg is 2344kg-3231kg, the forking performance is 2987kg-3671kg, the concentrated load of the plate surface is 7945kg-9870kg, and the comprehensive mechanical property strength is far superior to that in the comparative examples.
The experimental result of comparative example 4 shows that the allyl ether with n value greater than 5 requires longer pressure maintaining time to realize the compression molding of the tray under the same process conditions as those of example 4, the production efficiency is greatly reduced, and the comprehensive mechanical properties are obviously inferior to those of the examples.
Furthermore, as can be seen from the experimental results of examples 3-5, the compound a containing the structural formula (II) in the component II can realize compression molding of the pallet within a shorter pressure holding time than the compound a containing the structural formula (I), and the production efficiency can be further significantly improved on the premise of good mechanical properties of the product.
It should be understood that the above-described embodiments are merely examples for clarity of description and are not intended to limit the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.
Claims (28)
1. The polyurethane adhesive is characterized by being obtained by reacting reaction raw materials comprising a component I and a component II;
wherein the component I comprises isocyanate; the component II comprises polyether polyol and a compound A; the content of the compound A is 1ppm-1% based on the total mass of the component II;
the total amount of the component I and the component II is 100 parts by mass: the dosage of the component I is 80-99 parts by mass, and the dosage of the component II is 1-20 parts by mass;
the polyether polyol is selected from one or more of polyoxyethylene polyol and polyoxyethylene-propylene oxide polyol;
the compound A is selected from one or more of the following compounds with structural formula (I) and structural formula (II):
wherein n in the structural formula (I) and the structural formula (II) is an integer of 1-5 independently.
2. The polyurethane adhesive of claim 1, wherein the compound a is selected from one or more of the compounds of formula (II).
3. The polyurethane adhesive of claim 1, wherein the compound a is present in an amount of 1 to 500ppm, based on the total mass of the component II.
4. The polyurethane adhesive of any one of claims 1-3, wherein the total amount of component I and component II is 100 parts by mass:
the dosage of the component I is 85-95 parts by mass;
the amount of the component II is 3-10 parts by mass.
5. The polyurethane adhesive of any one of claims 1-3,
the polyether polyol is selected from one or more of polyoxyethylene polyol and polyoxyethylene-propylene oxide polyol with the molecular weight Mn of 1000-5000g/mol and the functionality of 2-4;
and/or the functionality of the isocyanate is more than or equal to 2.
6. The polyurethane adhesive of claim 5, wherein the polyether polyol is selected from one or more of polyoxyethylene polyol, polyoxyethylene-oxypropylene polyol having a molecular weight Mn of 3000-5000g/mol and a functionality of 2-4.
7. The polyurethane adhesive of claim 5, wherein the isocyanate is selected from the group consisting of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and polymethylene polyphenyl polyisocyanates.
8. The method of preparing polyurethane adhesive according to any one of claims 1 to 7, wherein the polyurethane adhesive is obtained by mixing and reacting the respective reaction raw materials.
9. The method of claim 8, wherein the reaction is carried out at 60 to 90 ℃.
10. The method of claim 9, wherein the reaction is carried out at 70-80 ℃.
11. The method of claim 9 or 10, wherein the reaction time is 1-4 hours.
12. The method of claim 11, wherein the reaction time is 1.5 to 2.5 hours.
13. The production method according to any one of claims 8 to 10, wherein the stirring rate during the reaction is 300 to 500rad/s.
14. The method according to claim 13, wherein the stirring speed during the reaction is 300 to 400rad/s.
15. Use of the polyurethane adhesive of any one of claims 1-7 in a molded article.
16. The use of claim 15, wherein the molded article comprises one or more of a molded sheet and a molded tray.
17. Use according to claim 15, wherein the substrate material of the moulded article comprises one or more of wood shavings, board, fibres.
18. Use according to claim 17, wherein the substrate material of the moulded article comprises one or more of wood shavings, boards, fibres of herbaceous and woody plant origin.
19. Use according to claim 15, wherein the substrate material of the moulded article comprises a material derived from the agricultural and forestry residues.
20. An aldehyde-free molded tray, wherein the adhesive used in the molded tray is the polyurethane adhesive according to any one of claims 1 to 7.
21. The aldehyde-free additive molding tray according to claim 20, wherein the base material of the molding tray comprises one or more of wood shavings, board, fibers.
22. The aldehyde-free molded tray of claim 21 wherein the base material of the molded tray comprises one or more of shavings, boards, fibers derived from herbs and woody plants.
23. The aldehyde-free additive molding tray according to claim 20, wherein the base material of the molded article comprises a material derived from agriculture and forestry residues.
24. The aldehyde-free molded tray according to claim 21, wherein the amount of the polyurethane adhesive used in the molded tray is 3 to 10% by mass of the base material.
25. The method of making an aldehyde-free addition-molded tray of any of claims 21-24, comprising the steps of:
1) Controlling the water content of the base material to be 8-20wt%;
2) Applying the polyurethane adhesive to the substrate material;
3) Applying a release agent on the mould of the hot press, then placing the substrate material obtained in step 2) in the mould of the hot press, and then carrying out hot pressing to form the moulded tray.
26. The manufacturing method according to claim 25, wherein the hot pressing is performed at a hot pressing temperature of 120 ℃ to 200 ℃, a dwell pressure of 13 Mpa to 20Mpa, and a dwell time of 80s to 300s in step 3).
27. The production method according to claim 26, wherein the dwell time is 80s to 250s.
28. The production method according to claim 27, wherein the dwell time is 80s to 200s.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102336292A (en) * | 2010-07-23 | 2012-02-01 | 信义光伏产业(安徽)控股有限公司 | Die pressing tray and production process of same |
| CN105881693A (en) * | 2016-06-18 | 2016-08-24 | 慈溪市普瑞箱包有限公司 | Molded tray and making process thereof |
| CN112391142A (en) * | 2019-06-19 | 2021-02-23 | 科思创知识产权两合公司 | Adhesive, preparation and application thereof |
| CN114058311A (en) * | 2020-08-05 | 2022-02-18 | 万华化学集团股份有限公司 | Modified isocyanate adhesive and preparation method thereof, aldehyde-free mould pressing tray and preparation method thereof |
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| ITRM20120259A1 (en) * | 2012-06-06 | 2013-12-07 | Bayer Internat Sa | PROCEDURE FOR THE PRODUCTION OF VISCOELASTIC POLYURETHANE FOAMS. |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102336292A (en) * | 2010-07-23 | 2012-02-01 | 信义光伏产业(安徽)控股有限公司 | Die pressing tray and production process of same |
| CN105881693A (en) * | 2016-06-18 | 2016-08-24 | 慈溪市普瑞箱包有限公司 | Molded tray and making process thereof |
| CN112391142A (en) * | 2019-06-19 | 2021-02-23 | 科思创知识产权两合公司 | Adhesive, preparation and application thereof |
| CN114058311A (en) * | 2020-08-05 | 2022-02-18 | 万华化学集团股份有限公司 | Modified isocyanate adhesive and preparation method thereof, aldehyde-free mould pressing tray and preparation method thereof |
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