JP3702452B2 - Method for producing a molded body of lignocellulosic material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a molded article having excellent physical properties with good processability by using an organic polyisocyanate composition excellent in releasability, water resistance and the like for lignocellulosic materials such as wood fibers. .
[0002]
[Prior art]
Conventionally, organic polyisocyanate resin has excellent processing / physical properties due to its outstanding adhesive properties as an adhesive for hot-pressed products (particle board, medium fiber board) of lignocellulosic materials such as wood chips and wood fibers. It is known to exhibit properties. However, due to its excellent adhesive properties, when the material is hot-pressed with a continuous or batch press, there arises an offsetting disadvantage that it strongly adheres to the metal surface (hot plate) to be contacted.
[0003]
Until now, in order to solve the problem of adhesion to the hot platen, it has been necessary to previously apply a release agent to the metal surface to form a release layer.
Rather than using an external mold release agent coating method, a method in which organic polyisocyanate and mineral wax are mixed and subjected to hot-press molding is applied as a method for applying a polycellulose to a lignocellulosic material at the same time as an organic polyisocyanate. It is proposed in 3-21321.
[0004]
[Problems to be solved by the invention]
However, in order to exert a sufficient release effect by this method, it is necessary to add a large amount of mineral wax into the system, and it has not been applied as it is to the current production process including economy.
Further, as a compatibilizing agent for this wax and polyisocyanate, there is known a method in which an orthophosphoric acid neutral ester is added and a lignocellulosic material is hot-press molded (Japanese Patent Laid-Open No. Hei 4-232004).
However, in this method, a liquid mixed solution of wax and neutral ester of orthophosphoric acid that is easy to operate at room temperature cannot be obtained, and there is a problem in handling the wax.
[0005]
[Means for Solving the Problems]
As a result of diligent research, the present inventors have found that uniform dispersion can be easily performed by using the wax in the form of an aqueous emulsion in advance, and it is easy to handle at room temperature, leading to the completion of the present invention. It was. That is, the present invention is a method for producing a lignocellulosic material molded body using an organic polyisocyanate compound as a binder, and (A) water-dispersible polymethylene polyphenylene polyisocyanate , and (B) a melting point in the range of 50 to 160 ° C. An aqueous emulsion of wax, and (C) a phosphoric acid (mono and / or di) aliphatic ester obtained by neutralizing a compound composed of phosphoric acid and a monoester and / or diester of an aliphatic alcohol having 12 to 20 carbon atoms with alkanolamine It adheres with the composition which consists of alkanolamine salt of this, The manufacturing method of the said lignocellulose type material molded object characterized by the above-mentioned.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The organic polyisocyanate in the present invention may be any organic polyisocyanate containing at least two isocyanate groups per molecule, such as diphenylmethane diisocyanate, toluylene diisocyanate, hexamethylene diisocyanate, and the like.
The term organic polyisocyanate in the present invention is a term that also includes an unmodified polyisocyanate as described above and a modified polyisocyanate that is urethane-modified with a polyol, for example.
Preferred organic polyisocyanates in the present invention are, for example, bifunctional or higher polymethylene polyphenylene polyisocyanates (hereinafter abbreviated as polymeric MDI) produced by phosgenation of aniline / formaldehyde condensates, and more preferable are water dispersibility. A water-dispersible polymeric MDI applied.
It is known that the water-dispersible polymeric MDI is obtained, for example, by reacting a polymeric MDI with a monofunctional hydroxyl group-containing substance such as a water-affinity alkoxypolyalkylene glycol having a number average molecular weight of about 250 to 4000.
Japanese Patent Publication No. 2-58287 discloses a water-dispersible polymeric MDI, specifically, “Wood Cure 300 (NCO content = 28.0 to 30.5%), from Japan Polyurethane Industry Co., Ltd. It can be obtained.
[0008]
The organic polyisocyanate may be an isocyanate group-terminated prepolymer obtained from a reaction between a polyol and an organic polyisocyanate.
Preferred isocyanate group-terminated prepolymers are obtained from the reaction of MDI and / or polymeric MDI with a polyol having hydrophilic groups and a number average molecular weight of 500-3000.
These polyols include polyether polyols containing 50 mol% or more of ethylene oxide units, polyesters having anionic groups such as sulfonate groups and carboxylate groups, polycarbonates, polyether polyols, and the like.
Preferred isocyanate-terminated prepolymers are those obtained from the reaction of polyether polyols having an NCO content of 20-30% and containing 50 mol% or more of ethylene oxide units with MDI and / or polymeric MDI.
As the organic polyisocyanate of the present invention, it is preferable to use water-dispersible polymeric MDI.
[0009]
The aqueous emulsion in the present invention is a known wax-based mold release agent having a melting point of 50 to 160 ° C., for example, natural wax such as montan wax, carnauba wax, rice wax, paraffin wax, polyethylene wax, montan wax derivative, paraffin Synthetic waxes such as wax derivatives, hardened castor oil, stearamide, etc. are made into aqueous emulsions. It is preferable to use a known emulsifier for emulsification. The solid content of the emulsion is preferably 10 to 50% by weight.
[0010]
The alkanolamine salt of a phosphoric acid (mono and / or di) ester (hereinafter abbreviated as an organic phosphate ester derivative) in the present invention is a product obtained by neutralizing a partially esterified product of alcohol and phosphoric acid with an alkanolamine. As said alcohol, a C12-C20 aliphatic alcohol is preferable, for example, stearyl alcohol and oleyl alcohol can be mentioned. In esterification with phosphoric acid, partial esterification is preferable, and monoester or diester, or a mixture thereof.
This partially esterified product is neutralized with alkanolamine and used as one component of the composition. Strict degree of neutralization is not required. The stoichiometric ratio may be in the range of 0.3 to 3.0. There may be incomplete neutralization with alkanolamines or there may be excess alkanolamines.
Examples of the alkanolamine for neutralization include monoethanolamine, diethanolamine, and triethanolamine.
The organic phosphate ester derivative may be an aqueous solution or a solution dissolved in an organic solvent.
[0011]
A lignocellulosic material molded body is obtained by attaching a polyisocyanate composition to a lignocellulosic material and compressing it by heating. Any molding conditions can be applied as long as they are known particle board molding conditions.
The aqueous emulsion of organic polyisocyanate and wax and the phosphate ester derivative are used by mixing the above three components immediately before being applied to the lignocellulosic material, or by separately applying them. In this case, it may be the four components [(A) + (B) + (C) + (D)] obtained by adding water to the three components [(A) + (B) + (C)]. . In other words, water may be added as the fourth component (D) in addition to the water contained in the three components.
Ingredients (A), (B), (C), (D) may be separately sprayed on the lignocellulosic material in any order in a batch mixer or continuous mixer. Preferably, a continuous mixing device is used.
In the mixing operation, the components (A), (B), (C), and (D) may be mixed in any order. However, it is preferred that (A) is finally mixed.
Further, (B) and (C) are preferably premixed, and a mixture of (A), (B), (C) and (D) is preferably sprayed.
When producing on a continuous line, it is preferable to use a premixed aqueous emulsion of wax and a phosphate ester derivative. The premix and water, and then the organic polyisocyanate are continuously mixed with a static mixer and sprayed onto the lignocellulosic material.
U.S. Pat. Nos. 5,093,058, 5,188,785 and 5,200,277 disclose the above-described manufacturing method and apparatus in a continuous line.
[0012]
The amount of each added to the lignocellulosic material is 5 to 20 parts by weight in solid content of the organic polyisocyanate and 0.5 to 0.5% in solid content of the aqueous wax wax with respect to 100 parts by weight of the dry lignocellulosic material. 4.0 weight part and a phosphate ester derivative are 0.1-2.0 weight part in solid content.
In order to keep the moisture content of the mat before hot pressing at a constant value, it is preferable to add water.
The amount of water to be added is calculated as the difference between the water content of the set mat moisture content and the water in the lignocellulosic material + water in the emulsion. The mat moisture content is set to 5 to 35% by weight, preferably 5 to 30% by weight.
[0013]
【The invention's effect】
As described above, by using the production method of the present invention, adhesion between the material and the metal surface can be prevented at the time of hot-pressure molding of lignocellulosic substances such as wood chips and wood fibers. Further, the wax at room temperature can be handled in a liquid state, and there is an advantage that a uniform emulsion can be obtained.
[0014]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further, it is not limited to this. In the examples, parts and% indicate parts by weight and% by weight, respectively.
[0015]
Example 1
Made by Nippon Polyurethane Industry, 20.1 g of water-emulsified MDI “WC-300”, manufactured by Orion Kasei Co., Ltd., Montan wax emulsion “MN-30” (solid content 30%) 16.8 g, phosphate ester derivative, dioleyl phosphate 1 g of 100 parts by weight of ester neutralized with 25 parts of triethanolamine and 35.9 g of distilled water were mixed in a laboratory mixer to obtain an aqueous emulsion solution.
This is 22.0 parts per 100 parts of dry chips (breakdown is water-emulsified MDI “WC-300” = 6 parts, montan wax emulsion = 5.0 parts, phosphate ester derivative = 0.3 parts, distilled water = 10.7 parts) was added, and hot pressing was performed under the following molding conditions.
At that time, an iron plate (SPCC-SB) made by Nippon Test Panel was placed on the top and bottom of the board to confirm the releasability.
〔Molding condition〕
Board size 25cm x 25cm
Board thickness 9mm
Set density 0.700 g / cm ³
Moisture content of chips 3% Moisture content of Rawan chips 9%
Matt moisture content 16%
Press temperature 160 ℃
Press pressure 30kg / cm ² (surface pressure)
Pressing time 12 seconds per board (108 seconds)
[0016]
As a result, the iron plate and the obtained board were easily peeled off, and no chip adhered to the iron plate. With respect to this board, the bending strength was measured in accordance with JIS A 5908. As a result, it was 320 kg / cm ² . The water absorption thickness expansion coefficient was measured in accordance with JIS A 5901 and found to be 5.0%.
The measurement method was similarly performed in the following examples.
[0018]
Comparative Example 1
Made by Nippon Polyurethane Industry, 19.9 g of water-emulsified MDI “WC-300”, made by Orion Kasei Co., Ltd., 33.2 g of montan wax emulsion “MN-30” (solid content 30%), and 24.5 g of distilled water in a laboratory mixer An aqueous emulsion solution was obtained by mixing. Add 23.4 parts of this to 100 parts of dry chips (breakdown is water-emulsified MDI “WC-300” = 6 parts, montan wax emulsion = 10.0 parts, distilled water = 7.4 parts) Hot pressing was performed under the same molding conditions as in Example 1.
As a result, the iron plate and the board were firmly attached and could not be peeled off.
[0019]
Comparative Example 2
Made by Nippon Polyurethane Industry, 19.9 g of water-emulsified MDI “WC-300”, manufactured by Orion Kasei Co., Ltd., 19.9 g of carnauba wax emulsion “BN-50” (solid content 50%), and 37.8 g of distilled water using a laboratory mixer An aqueous emulsion solution was obtained by mixing. 23.4 parts of this was added to 100 parts of dry chips (breakdown is water-emulsified MDI “WC-300” = 6 parts, carnauba wax emulsion = 6 parts, distilled water = 11.4 parts). Was hot-press molded under the same molding conditions.
As a result, the iron plate and the board were firmly attached and could not be peeled off.
[0020]
Comparative Example 3
Made by Nippon Polyurethane Industry, 20.4 g of water-emulsified MDI “WC-300”, manufactured by Axel PLASTICS RESEARCH LABORATORIES, 1.0 g of phosphate ester derivative MOLD WIZ INT-1858 (100% solid content), 47.5 g of distilled water An aqueous emulsion solution was obtained by mixing with a lab mixer. 20.3 parts of this is added to 100 parts of dry chips (breakdown is water-emulsified MDI “WC-300” = 6 parts, phosphate ester derivative = 0.3 parts, distilled water = 14.0 parts), Hot pressing was performed under the same molding conditions as in Example 1.
As a result, the iron plate and the board were firmly attached and could not be peeled off.
[0021]
Comparative Example 4
Made by Nippon Polyurethane Industry, 20.4 g of water-emulsified MDI “WC-300”, manufactured by Axel PLASTICS RESEARCH LABORATORIES, 3.4 g of phosphate ester derivative MOLD WIZ INT-1858 (100% solid content), 47.6 g of distilled water An aqueous emulsion solution was obtained by mixing with a lab mixer. 21.1 parts of this is added to 100 parts of dry chips (breakdown is water-emulsified MDI “WC-300” = 6 parts, phosphate ester derivative = 1.0 part, distilled water = 14.1 parts), Hot pressing was performed under the same molding conditions as in Example 1.
As a result, the iron plate and the board were easily peeled off, and no chip adhered to the iron plate.
The bending strength of this board was 272 kg / cm ² , the water absorption thickness expansion coefficient was 18.3%, and the water resistance was extremely poor as compared with Examples 1 to 3.
[0022]
Comparative adjustment example 1
In a 50 ml sample bottle, 7.5 g of montan wax having a melting point of 75 to 85 ° C. and 12.5 g of 2-ethylhexyl diphenyl phosphate were added and dissolved at a temperature of 95 ° C. When the solution is uniformly dissolved as it is, heating is stopped and the mixture is allowed to cool. There was no fluidity at room temperature.

Claims (1)

In the method for producing a lignocellulosic material molded body using an organic polyisocyanate compound as a binder, (A) a water-dispersible polymethylene polyphenylene polyisocyanate , and (B) an aqueous emulsion of a wax having a melting point in the range of 50 to 160 ° C., (C) an alkanolamine salt of phosphoric acid (mono and / or di) aliphatic ester obtained by neutralizing a compound comprising phosphoric acid and a monoester and / or diester of an aliphatic alcohol having 12 to 20 carbon atoms with alkanolamine ; It adheres with the composition which consists of this, The manufacturing method of the said lignocellulosic material molding.