JP2023087731A - Self-emulsifying polyisocyanate for adhesive for hot-pressed molded body, adhesive composition for hot-pressed molded body and hot-pressed molded body - Google Patents

Abstract

To provide a self-emulsifying polyisocyanate for an adhesive for a hot-pressed molded body and an adhesive composition for a hot-pressed moded body which contribute to the production of a hot-pressed molded body having excellent curability and high strength.SOLUTION: There is provided a self-emulsifying polyisocyanate for an adhesive for a hot-pressed molded body which contains a first self-emulsifying polyisocyanate which is a reaction product of a first self-emulsifying polyisocyanate precursor and a first polyether compound having an ethylene oxide unit, wherein the first self-emulsifying polyisocyanate precursor is any one or more polyisocyanates selected from the group consisting of an aliphatic diisocyanate, an alicyclic diisocyanate and a modified polyisocyanate thereof, the polyisocyanate contains one or more selected from the group consisting of an isocyanurate bond, an allophanate bond and a urethane bond and the content of the first self-emulsifying polyisocyanate is 8 to 100 mass%.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present disclosure relates to a self-emulsifying polyisocyanate for use as an adhesive for hot-pressed articles, an adhesive composition for hot-pressed articles, and a hot-pressed article.

Boards such as particle boards and medium-density fiberboards called MDF (medium-density fiberboard) are known as hot-press molded bodies made of lignocellulose materials such as wood chips and wood fibers. Examples of adhesives for hot-press molded products of substrates made of wood-based materials or non-wood-based materials include, for example, emulsion-type adhesives composed of self-emulsifying polyisocyanates obtained by introducing hydrophilic groups into organic polyisocyanates and water. of adhesive is used.
Wood-based boards are used in a wider range of applications than just for furniture and construction, and are also being used for structural purposes in the construction field, and higher strength than ever before is required.
Here, Patent Document 1 discloses a method for producing a thermo-compression-molded wooden board in which a wood fiber-based material is previously impregnated with an isocyanurate-forming catalyst, and an organic polyisocyanate compound is spray-coated as an adhesive during molding.

Japanese Patent Application Laid-Open No. 2003-276011

However, the method for producing a hot-pressed wooden board according to Patent Document 1 is not efficient because it requires impregnation of the base material with the isocyanurate-forming catalyst. Therefore, there is a strong demand for an adhesive composition for hot-press molded articles that can achieve both strength and curability without impregnating the base material with an isocyanurate-forming catalyst in the production of hot-press molded articles. there is
Therefore, one aspect of the present disclosure is a self-emulsifying polyisocyanate for an adhesive of a thermo-pressed body that has excellent curability and contributes to the production of a high-strength thermo-pressed body, and an adhesive for a thermo-pressed body. It is directed to provide a composition. Further, another aspect of the present disclosure is directed to providing a thermo-compression molded article with excellent productivity and high strength.

According to one aspect of the present disclosure,
The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1),
The first self-emulsifying polyisocyanate (a1) is
a first self-emulsifying polyisocyanate precursor (a1-1);
A reaction product of a first polyether compound (a1-2) having an ethylene oxide unit,
The first self-emulsifying polyisocyanate precursor (a1-1) is
an aliphatic diisocyanate (a1-1-1), and
Alicyclic diisocyanate (a1-1-2), and
Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these,
The polyisocyanate (a1-1-3) contains at least one selected from the group consisting of isocyanurate bonds, allophanate bonds and urethane bonds,
The content of the first self-emulsifying polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifying polyisocyanate (A). Type polyisocyanate (A) is provided.

According to another aspect of the present disclosure,
The self-emulsifying polyisocyanate (A),
and a curing accelerator (B).

According to yet another aspect of the present disclosure,
a base material for a thermo-pressed body;
A thermo-pressurized article is provided, comprising: a thermo-pressurized cured product of the adhesive composition for thermo-pressurized articles obtained by adhering the base material for the thermo-pressurized article.

According to one aspect of the present disclosure, a self-emulsifying polyisocyanate for an adhesive of a thermo-pressed product that contributes to the production of a thermo-pressed product having excellent curability and high strength, and an adhesive for the thermo-pressed product A composition can be provided. Further, according to another aspect of the present disclosure, it is possible to provide a thermo-compression molded article with excellent productivity and high strength.

Exemplary embodiments for implementing aspects of the present disclosure are described in detail below.

<Adhesive Composition for Thermo-Pressed Articles, Self-Emulsifying Polyisocyanate for Adhesive for Thermo-Pressed Articles>
[Self-emulsifying polyisocyanate (A)]
The self-emulsifying polyisocyanate (A) for the adhesive of the hot-press molded body according to one aspect of the present disclosure is
The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1),
The first self-emulsifying polyisocyanate (a1) is
a first self-emulsifying polyisocyanate precursor (a1-1);
A reaction product of a first polyether compound (a1-2) having an ethylene oxide unit,
The first self-emulsifying polyisocyanate precursor (a1-1) is
an aliphatic diisocyanate (a1-1-1), and
Alicyclic diisocyanate (a1-1-2), and
Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these,
The polyisocyanate (a1-1-3) contains at least one selected from the group consisting of isocyanurate bonds, allophanate bonds and urethane bonds,
The content of the first self-emulsifying polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifying polyisocyanate (A).
Further, the adhesive composition for thermocompression molding according to one aspect of the present disclosure is
The self-emulsifying polyisocyanate (A),
and a curing accelerator (B).

Next, the constituent components of the self-emulsifying polyisocyanate (A) for use as an adhesive for hot-press molded articles and the adhesive composition for hot-press molded articles will be described.

[[First self-emulsifying polyisocyanate (a1)]]
The self-emulsifying polyisocyanate (A) contains the first self-emulsifying polyisocyanate (a1).
The first self-emulsifying polyisocyanate (a1) is
a first self-emulsifying polyisocyanate precursor (a1-1);
It is a reaction product with the first polyether compound (a1-2) having ethylene oxide units.

The first self-emulsifying polyisocyanate precursor (a1-1) is
an aliphatic diisocyanate (a1-1-1), and
Alicyclic diisocyanate (a1-1-2), and
Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these.

Aliphatic diisocyanates (a1-1-1) include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxy ethylene diisocyanate, and the like.

The alicyclic diisocyanate (a1-1-2) includes isophorone diisocyanate, cyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate, and the like. are mentioned.

Polyisocyanate (a1-1-3) is polyisocyanate (a1-1-3) obtained by modifying aliphatic diisocyanate (a1-1-1) or alicyclic diisocyanate (a1-1-2). . Polyisocyanate (a1-1-3) contains at least one selected from the group consisting of isocyanurate bonds, allophanate bonds and urethane bonds.
Polyisocyanate (a1-1-3) preferably contains an isocyanurate bond obtained by modifying hexamethylene diisocyanate.

Aliphatic diisocyanate (a1-1-1), alicyclic diisocyanate (a1-1-2), and polyisocyanate (a1-1-3) obtained by modifying these are used alone or in combination of two or more. can be used in combination.

As the first self-emulsifying polyisocyanate precursor (a1-1), hexamethylene diisocyanate or a modified product thereof is particularly preferable from the viewpoint of strength development and durability.

Specific methods for producing the polyisocyanate (a1-1-3) are described below.
Polyisocyanate (a1-1-3) can be produced using diisocyanate as a starting material. For example, it can be produced by isocyanurate-forming reaction, allophanat-forming reaction, urethanating reaction, or the like, and then removing unreacted diisocyanate monomers. Unreacted diisocyanate does not necessarily need to be removed, but is preferably removed from the point of view of odor and the like.

-Urethanization of polyisocyanate (a1-1-3) The reaction time varies depending on the presence or absence of a catalyst and the type of isocyanate, but is generally within 10 hours, preferably 1 to 5 hours. The reaction temperature is 40-120°C, preferably 60-100°C. A known urethanization catalyst can be used in the urethanization reaction. Specific examples of urethanization catalysts include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate; organic amines such as triethylenediamine and triethylamine; and salts thereof. These catalysts can be used alone or in combination of two or more.

Isocyanurate-forming catalyst of polyisocyanate (a1-1-3) The isocyanurate-forming catalyst used in the reaction can be appropriately selected from known catalysts and used. Examples of the isocyanurate-forming catalyst include metal salts of carboxylic acids and tetraalkylammonium salts.
Examples of metals constituting metal salts of carboxylic acids include alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (magnesium, calcium, barium, etc.), and other typical metals (zinc, tin, lead, etc.). mentioned. Tetraalkylammonium salts include, for example, tetramethylammonium octylate. These catalysts can be used alone or in combination of two or more.

The content of the isocyanurate-forming catalyst is preferably 0.0001% by mass or more and 0.01% by mass or less, more preferably 0.0005% by mass or more and 0.003% by mass or less, relative to the total mass of the diisocyanate and the polyol. When it is 0.0001% by mass or more, the isocyanurate-forming reaction proceeds more easily, and the reaction time can be further reduced. When it is 0.01% by mass or less, it is possible to further suppress runaway reaction due to rapid heat generation, further reduce coloring of the prepolymer, and further suppress unnecessary viscosity increase.

Here, the reaction temperature for the isocyanurate-forming reaction is 40 to 80.degree. C., preferably 50 to 70.degree. When the reaction temperature is 40° C. or higher, the isocyanurate-forming reaction proceeds more easily and the reaction time can be further reduced. When the reaction temperature is 80° C. or lower, it is possible to further suppress the formation of the polymer, further reduce the coloring of the prepolymer, and further suppress the unnecessary increase in viscosity.

Allophanatization of polyisocyanate (a1-1-3) The allophanatization catalyst used in the reaction can be appropriately selected from known catalysts and used. Examples of allophanatization catalysts include metal salts of carboxylic acids.

Examples of metals constituting metal salts of carboxylic acids include typical metals (zinc, tin, lead, etc.), transition metals (manganese, iron, cobalt, nickel, copper, zirconium, etc.), and the like. These catalysts can be used alone or in combination of two or more. The content of the allophanatization catalyst is preferably 0.001% by mass or more and 0.1% by mass or less, more preferably 0.005% by mass or more and 0.03% by mass or less, relative to the total mass of the diisocyanate and the polyol. When the amount is 0.001% by mass or more, the allophanatization reaction proceeds more easily, and the reaction time can be further reduced. When it is 0.1% by mass or less, the formation of by-products such as allophanate group-containing polyisocyanate and nurate group-containing polyisocyanate having a high molecular weight is suppressed, the increase in viscosity is further suppressed, and the purity is further increased.

Here, the allophanatization reaction is carried out at a reaction temperature of 70 to 150°C, preferably 90 to 130°C. When the reaction temperature is 70°C or higher, the reaction proceeds more easily and the reaction time can be further reduced. When the reaction temperature is 150° C. or lower, it is possible to further suppress the generation of by-products such as allophanate group-containing polyisocyanate having a high molecular weight and to further suppress an unnecessary increase in viscosity.

- Catalyst poison After the isocyanurate or allophanatization reaction, a catalyst poison is added to terminate the isocyanurate or allophanatization reaction.
As for the timing of adding the catalyst poison in the isocyanurate reaction, it is preferable to add it immediately after reaching the desired NCO content.
The timing of adding the catalyst poison in the allophanatization reaction is not particularly limited, but in order to suppress the progress of side reactions, it is preferably added immediately after the completion of the reaction.

Examples of the catalyst poison include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having a sulfonic acid group and a sulfamic acid group, esters thereof, and known compounds such as acyl halides. These catalyst poisons can be used alone or in combination of two or more.

Although the content of the catalyst poison varies depending on the type of the catalyst poison and the catalyst, it is preferably 0.5 equivalents or more and 10 equivalents or less, particularly preferably 0.8 equivalents or more and 5.0 equivalents or less. When the amount of the catalyst poison is 0.5 equivalents or more, deterioration of storage stability such as reduction in NCO content, increase in viscosity, and coloration of the resulting polyisocyanate can be further suppressed. When the amount is 10 equivalents or less, coloring of the polyisocyanate can be further suppressed.

In the purification step, free unreacted diisocyanate monomers present in the reaction mixture are removed, for example, by thin film distillation at 120-140° C. under high vacuum of 10-100 Pa to a residual content of 1.0% by weight or less. It is preferable to remove up to a ratio. When the residual content is 1.0% by mass or less, the odor can be further reduced, and deterioration of storage stability can be further suppressed.

Among the polyisocyanates obtained by the above operation, polyfunctional polyisocyanates containing isocyanurate bonds (eg, product name C-HX, manufactured by Tosoh Corporation) are particularly preferred.

- Content of the first self-emulsifying polyisocyanate (a1) The content of the first self-emulsifying polyisocyanate (a1) in the self-emulsifying polyisocyanate (A) is 8% by mass or more and 100% by mass or less. and more preferably 20% by mass or more and 80% by mass or less.
It is preferable that the polyisocyanate (a1-1-3) is 8% by mass or more because the bending strength of the resulting molded article is excellent. When the polyisocyanate (a1-1-3) is 80% by mass or less, the viscosity of the self-emulsifying polyisocyanate (A) before emulsification at 25° C. is low (for example, it is easy to keep it at 5000 mPa·s or less), which is preferable. .

The first polyether compound (a1-2) is a polyether compound having ethylene oxide units.
The first polyether compound (a1-2) preferably contains 5 or more ethylene oxide units on average.
More preferably, the first polyether compound (a1-2) contains 80% by mass or more of oxyethylene units and has an average functional number of hydroxyl groups of 1.5 or less per molecule. When the oxyethylene unit is 80% by mass or more, it becomes easy to form a uniform emulsion when emulsified with water when used as an adhesive, and the dispersion on the substrate becomes uniform. Further, when the average number of functional groups is 1.5 or less, it becomes easier to form an emulsion, and shortening of the pot life due to thickening or the like can be further suppressed.

As the first polyether compound (a1-2), ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc. are ring-opening polymerized using an initiator described later, and the functional group number is 1 to 5, and the number average molecular weight is 300. 10,000 polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and the like; and polyether polyols copolymerized therewith. Examples of the first polyether compound (a1-2) further include known polyester polyols and polyester ether polyols using a polycarbonate polyol as an initiator.
Examples of initiators include various monoalcohols, glycols, glycol ethers, monoamines, diamines, aminoalcohols, water, urea, etc. having a number of functional groups of 1 to 5 and a number average molecular weight of 18 to 500.
The above compounds may be used alone, or two or more of them may be used as a mixture.

[[Second self-emulsifying polyisocyanate (a2)]]
The self-emulsifying polyisocyanate (A) preferably further contains a second self-emulsifying polyisocyanate (a2).
The second self-emulsifying polyisocyanate (a2) is
a polyphenylene polymethylene polyisocyanate (a2-1);
It is a reaction product with a second polyether compound (a2-2) containing an average of 5 or more ethylene oxide units.

Polyphenylene polymethylene polyisocyanate (a2-1) is diphenylmethane diisocyanate (hereinafter also referred to as MDI) containing two benzene rings and two isocyanate groups, and a polynuclear mixture containing three or more benzene rings and three or more isocyanate groups. is. Polyphenylene polymethylene polyisocyanate (a2-1) may contain a small amount of impurities in addition to these. Examples of impurities include isocyanate dimers, polynuclear methylated or chlorinated products, carbodiimide compounds, uretonimine compounds, and the like. Polyphenylene polymethylene polyisocyanate is also referred to as polymeric MDI. Commercial products of polyphenylene polymethylene polyisocyanate (a2-1) include, for example, crude diphenylmethane diisocyanate MR-200 (MDI content: 35 to 45%) manufactured by Tosoh Corporation.

The second polyether compound (a2-2) containing an average of 5 or more ethylene oxide units contains 80% by mass or more of oxyethylene units, and the average functional number of hydroxyl groups per molecule is 1.5 or less. is preferred. When the oxyethylene unit is 80% by mass or more, it becomes easy to form a uniform emulsion when emulsified with water when used as an adhesive, and the dispersion on the substrate becomes uniform. Further, when the average number of functional groups is 1.5 or less, it becomes easier to form an emulsion, and shortening of the pot life due to thickening or the like can be further suppressed.

Examples of the second polyether compound (a2-2) include the same as the first polyether compound (a1-2) described above. Also, the second polyether compound (a2-2) may be the same as or different from the first polyether compound (a1-2).

[Curing accelerator (B)]

The curing accelerator (B) accelerates reaction curing with the base material and reaction curing with water as an adhesive. are mentioned. Examples of the catalyst include known urethanization catalysts such as tertiary amine-based catalysts, hydroxyl-containing amine-based catalysts, and metal-based catalysts. These urethanization catalysts may be used alone or in combination of two or more.

Examples of tertiary amine catalysts include triethylamine, triethylenediamine, N-methylmorpholine, N-methylimidazole, 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, 1-cyanoimidazole, and 1-cyanomethylimidazole. , 1,2-dimethylimidazole, 1,4-dimethylimidazole, 1-methyl-2-ethylimidazole, 1-methyl-4-ethylimidazole, 1-ethyl-2-methylimidazole, 1-ethyl-4-methylimidazole , pyridine, α-picoline and the like.

Examples of amine-based catalysts having a hydroxyl group include monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N,N,N'-trimethylaminoethylethanolamine, N,N,N',N '-tetramethylhydroxypropylenediamine and the like.

Examples of metal-based catalysts include dibutyltin dilaurate, dioctyltin dilaurate, calcium naphthenate, potassium octylate, tin octylate, and zinc octylate.

Among these, an aliphatic tertiary amine compound is preferable, and if it is a reactive catalyst, the diffusion from the molded article after hot pressing is suppressed, and the curing time can be easily adjusted, so the active hydrogen group-containing aliphatic A tertiary amine compound is more preferred, and a hydroxyl group-containing aliphatic tertiary amine is particularly preferred.

The content of the curing accelerator (B) is preferably an amount corresponding to the first self-emulsifying polyisocyanate (a1) in the self-emulsifying polyisocyanate (A).
The content of the curing accelerator (B) is preferably 0.1% by mass or more and 10% by mass or less with respect to the first self-emulsifying polyisocyanate (a1), and 0.5% by mass or more and 5% by mass. % or less is particularly preferred. When the content of the curing accelerator (B) is 0.1% by mass or more, the curing reaction is accelerated, the productivity is improved by shortening the reaction time, and the heat pressure is sufficient. physical properties tend to be better. When the content of the curing accelerator (B) is 10% by mass or less, the content of the curing accelerator (B) in the adhesive composition for thermocompression molded articles does not become too large, and adhesive bonding does not deteriorate over time. , and deterioration of durability appearing as deterioration of physical properties resulting therefrom can be further suppressed.

The adhesive composition is, for example, a two-liquid mixing type adhesive containing a first liquid containing a self-emulsifying polyisocyanate (A) and a second liquid in which components other than the first liquid are mixed in advance. is. At this time, the first liquid is preferably a mixed liquid in which the first self-emulsifying polyisocyanate (a1) and the second self-emulsifying polyisocyanate (a2) are mixed at a predetermined ratio.

[Other ingredients]
The adhesive composition for hot-pressed bodies may optionally contain inorganic fillers such as cement, blast furnace slag, gypsum, calcium carbonate, clay, aluminum hydroxide, antimony trioxide, quicklime, slaked lime and bentonite, and leveling agents. , a flame retardant, an anti-aging agent, a heat resistance imparting agent, an antioxidant, and the like.

<Thermal compression molding>
A thermocompression molded article according to one aspect of the present disclosure includes
a base material for a thermo-pressed body;
and a hot-press cured product of the above-mentioned adhesive composition for hot-press molded products, which is formed by adhering the base material for hot-press molded products.

A hot-press molded product is obtained by bonding (curing) a substrate for a hot-press molded product with the adhesive composition described above.
The base material for the hot-pressed body is preferably an aggregate of small pieces. The small pieces are prepared, for example, by crushing, cutting, fibrillating, or the like a raw material (before being made into small pieces) into small pieces. The pieces are preferably subjected to molding after drying.
The shape of the small pieces constituting the substrate is preferably needle-like, powder-like, fiber-like, or strand-like, and a desired shape is selected according to the type of the molded article.
The size of the small pieces constituting the substrate is preferably in the range of 4 mesh to 250 mesh.
As for the shape of the base material, it is particularly preferable that aggregates of these needle-like, powder-like or fibrous small pieces are sifted into a mat-like shape.
The uncured adhesive composition for hot-press molding enters into the gaps between the aggregates of the small pieces. Then, by applying heat and pressure to this, the adhesive composition for thermocompression molding becomes a thermocompression cured product, and adheres the small pieces constituting the base material.

Examples of the substrate include one selected from the group consisting of woody substrates, plant-based substrates, and recycled substrates; or two or more composite substrates.

Examples of wood-based substrates include (1) aggregates of small pieces such as strand chips, dust chips, and flake chips, which are wooden chips, (2) aggregates of small pieces such as lamina, and (3) fibrous (woody aggregates of small pieces in the form of system fibers).
Particle board, oriented strand board (OSB), wafer board, etc. are mentioned as the thing by which the aggregate|assembly of (1) was heat-pressed. Examples of the assembly (2) formed by thermocompression molding include laminated veneer lumber (LVL), laminated strand lumber (LSL), parallel strand lumber (PSL), and the like. Hardboards, medium-density fiberboards (MDF), insulation boards and the like are examples of the aggregates of (3) that are thermocompressed.

Non-woody base materials include fiber (non-woody), sorghum stem, bagasse, rice husk, hemp, straw, rush, reed, coconut and tree, rubber tree, corn, small pieces of plant such as sawdust. aggregates.

Recycled substrates include aggregates of small pieces such as used paper and cloth.

Among these, lignocellulosic materials are preferred. Moreover, these may be used alone (one type), or may be a composite base material in which two or more types are combined.

The content of the self-emulsifying polyisocyanate (A) is preferably 2% by mass or more and 50% by mass or less, and 4% by mass or more and 30% by mass or less, relative to the base material for the thermocompression molding. is more preferred.

An example of the method for producing a thermocompression molded body will be described below.
First, the above-described adhesive composition for hot-press molded articles is applied to a base material for hot-press molded articles.
When applying, for example, one of the following coating liquids (I) and (II) is applied.
(I): Coating in which a mixture of the first self-emulsifying polyisocyanate (a1), the second self-emulsifying polyisocyanate (a2), and the curing accelerator (B) is mixed immediately before applying to the substrate. liquid.
(II): Emulsify a mixture of the first self-emulsifying polyisocyanate (a1) and the second self-emulsifying polyisocyanate (a2) with a system of a mixture of the curing accelerator (B) and the solid content adjustment water. Mixed coating liquid.

When manufacturing in a continuous line, for example, it can be carried out according to the following (1) to (6).
(1) in advance,
Mixing the first self-emulsifying polyisocyanate (a1) and the second self-emulsifying polyisocyanate (a2) to prepare a first premix,
Separately, the curing accelerator (B), each component other than the self-emulsifying polyisocyanate (A) and the curing accelerator (B), and water are mixed to prepare a second premix,
(2) continuously mixing the first preliminary mixture and the second preliminary mixture with a static mixer or the like to prepare a mixture;
(3) applying the resulting mixture to a substrate,
(4) dispersing and depositing the base material coated with the mixed liquid to prepare a deposit;
(5) pre-compacting the sediment to form a mat;
(6) The mat is hot-pressed to obtain a hot-press molded product.

The hot press conditions may be applied by appropriately combining known molding conditions. Preferable hot press conditions include, for example, the following temperature, pressure, and time conditions.
Temperature: 100-250°C
Pressure: 1-10MPa
Time (per 1 mm of thickness): 6 to 30 seconds More preferably, the following conditions are met.
Temperature: 150-230°C
Pressure: 2-5MPa
Time (per mm of thickness): 6-15 seconds

EXAMPLES The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples. "Parts" and "%" in the text are based on mass unless otherwise specified.

[Synthesis of self-emulsifying polyisocyanate]
・Synthesis example 1
Using a reactor with a capacity of 2,000 ml equipped with a stirrer, thermometer, cooler and nitrogen gas inlet tube, 970 g of polyisocyanate (a1-1) shown in Table 1 and MPEG-400 (a1-2) After charging 30 g, the temperature was raised to 80° C. and reacted for 3 hours to obtain polyisocyanate (A1).
・Synthesis example 2
Polyisocyanate (a1-1) 970 g of Synthesis Example 1 to polymeric MDI (a2-1) 970 g, MPEG-400 (a1-2) 30 g to MPEG-700 (a2-2) Synthesis Example 1 except changing 30 g to obtain a polyisocyanate (A2).

Table 1 shows the types of raw materials, blending amounts, and analytical values.
Polyisocyanate (a1-1) was directly used as polyisocyanate (A3), and polymeric MDI (a2-1) was directly used as polyisocyanate (A4).

In Table 1, the details of each raw material are as follows.
・ Polyisocyanate (a1-1)
Manufactured by Tosoh Corporation, product name C-HX, NCO content = 21.7%
・Polymeric MDI (a2-1)
Manufactured by Tosoh Corporation, product name Millionate MR-200, NCO content = 30.5%
・MPEG-400(a1-2)
Kahwa Chemical Co., Ltd., product name Surfant MPEG400, polyethylene glycol monomethyl ether 400, number average molecular weight = 400
・MPEG-700(a2-2)
Kahwa Chemical Co., Ltd., product name Surfant MPEG750, polyethylene glycol monomethyl ether 700, number average molecular weight = 700

The standard formulation viscosity is the viscosity of the emulsion when the solid content is 50% in (A1) and (A2), and the viscosity of each polyisocyanate in (A3) and (A4).

[Standard formulation viscosity measurement]
Standard formulation viscosity was measured by the following procedure.
(1) Self-emulsifying polyisocyanates (A1) and (A2) preliminarily temperature-controlled to 25° C. and distilled water were used to prepare emulsions each having a solid content of 50%.
(2) Using a B-type viscometer TVB-10M manufactured by Toki Sangyo Co., Ltd., the viscosities of the emulsions (A1) and (A2) and the polyisocyanates (A3) and (A4) whose temperature was similarly adjusted to 25 ° C. were measured. .
(3) (A1), (A2) and (A4) were measured at 30 rotations of the No. 1 rotor, and (A3) was measured at 60 rotations of the No. 4 rotor.

[Curability test]
In a 200 cc cup, prepare a total of 40 g of a mixture of various ingredients and water (the solid content is set to 50%) in the amounts shown in Table 2, and use a small mixer with a rotation speed of 5000 rpm. After stirring for 30 seconds, the mixture was further stirred with a stirring rod in a hot water bath at 95°C. At this time, the time from when the mixture was placed in the hot water bath until it became difficult to stir due to thickening due to the progress of the curing reaction was measured and used as the curing time.

[Molding method of thermo-pressed product]
Molding conditions Board size: 30 cm x 30 cm
Board thickness: 10mm
Set density: 720kg/ ^m3
Product moisture content: 9% by mass
Mat moisture content: 14% by mass
Hot platen (press) temperature: 180°C
Hot platen (press) pressure: 3 MPa (surface pressure)
Hot platen (press) time: 150 seconds

The thermocompression molded articles shown in Table 2 were produced by the following method. In addition, it is common to all the following examples and comparative examples.
The base material (wood fiber) in the amount shown in Table 2 is put into a blender with a volume of about 50 L equipped with a stirring blade, and a mixture of various components and moisture content adjustment water in the amount shown in Table 2 is added thereto. It was spray applied with mixing and agitation for 1 minute. After that, the base material coated with the mixture was taken out, weighed so that the density of the molded body after molding reached the set density (720 kg/m ³ ), and was placed on a SUS-304 test panel coated with a release agent. It was spread and deposited in a frame set to have the board size (30 cm×30 cm). Then, a mat was formed by preliminary compression, and the frame was removed. Furthermore, a test panel coated with a release agent having the same shape was placed thereon, and thermocompression molding was performed under the molding conditions described above.

Curing accelerator (B) manufactured by Tosoh Corporation, product name TOYOCAT-A30

[Physical property measurement]
The flexural strengths of the moldings of Examples 1 to 5 and Comparative Examples 1 to 5 in Table 2 were measured according to JIS A-5908.

Examples 1-5
To the self-emulsifying polyisocyanate (a1-1) was introduced the self-emulsifying polyisocyanate (A1) and the curing accelerator (B) in an amount of 5% with respect to the introduced amount of (A1). The strength tended to increase as the amount of substitution of (A2) with (A1) increased.

Comparative Examples 1-2
Using the same base material as in Examples, only the self-emulsifying polyisocyanate (a2-1) and 5% of the polyfunctional polyisocyanate (A1) were introduced into the binder resin. Both Comparative Examples 1 and 2 had comparable strength, and the strength was lower than the level of each example.

Comparative example 3
Molding was carried out in the same manner as in Example 5, except that the curing accelerator (B) was not used. As a result, in Comparative Example 3, sufficient strength was not obtained.

Comparative example 4
Although only the non-self-emulsifying polyisocyanate (A3) was used, its viscosity was so high that it could not be spray-coated onto the substrate and could not be molded.

Comparative example 5
Using only non-self-emulsifying polymeric MDI (A4), molding was carried out in the same manner. The dispersion in the base material was insufficient, and many glue spots were observed in the molded article, and the strength was lowered.

Claims (11)

A self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed moldings,
The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1),
The first self-emulsifying polyisocyanate (a1) is
a first self-emulsifying polyisocyanate precursor (a1-1);
A reaction product of a first polyether compound (a1-2) having an ethylene oxide unit,
The first self-emulsifying polyisocyanate precursor (a1-1) is
an aliphatic diisocyanate (a1-1-1), and
Alicyclic diisocyanate (a1-1-2), and
Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these,
The polyisocyanate (a1-1-3) contains at least one selected from the group consisting of isocyanurate bonds, allophanate bonds and urethane bonds,
The content of the first self-emulsifying polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifying polyisocyanate (A). type polyisocyanate (A). further comprising a second self-emulsifying polyisocyanate (a2),
The second self-emulsifying polyisocyanate (a2) is
a polyphenylene polymethylene polyisocyanate (a2-1);
2. The self-emulsifying polyisocyanate (A) for use as an adhesive for hot-press molding according to claim 1, which is a reaction product of the second polyether compound (a2-2) having ethylene oxide units. Both the first polyether compound (a1-2) and the second polyether compound (a2-2) contain 80% by mass or more of oxyethylene units, and per molecule 3. The self-emulsifying polyisocyanate (A) according to claim 1 or 2, wherein the average functionality of hydroxyl groups is 1.5 or less. The self-emulsifying polyisocyanate (A) according to any one of claims 1 to 3, wherein the polyisocyanate (a1-1-3) contains an isocyanurate bond obtained by modifying hexamethylene diisocyanate. The self-emulsifying polyisocyanate (A) according to any one of claims 1 to 4,
and a curing accelerator (B). The thermocompression molding according to claim 5, wherein the content of the curing accelerator (B) is 0.1% by mass or more and 10% by mass or less with respect to the first self-emulsifying polyisocyanate (a1). Body adhesive composition. 7. The adhesive composition for thermocompression molding according to claim 5, wherein said curing accelerator (B) contains an aliphatic tertiary amine compound. 8. The adhesive composition for thermocompression molding according to claim 7, wherein said curing accelerator (B) is an active hydrogen group-containing aliphatic tertiary amine compound. a base material for a thermo-pressed body;
A thermo-pressed article comprising a thermo-pressurized product of the adhesive composition for a thermo-pressed article according to any one of claims 5 to 8, which is formed by adhering the base material for the thermo-pressed article. . A thermocompression molded article, wherein the base material is one selected from the group consisting of a wood base material, a plant base material, and a recycled base material; or a composite base material of two or more types. 11. The thermocompression molded article according to claim 9 or 10, wherein the base material is a lignocellulosic material.