JP2022147272A - Method for producing kraft lignin-containing phenolic resin - Google Patents

Abstract

To provide a method in which a phenolic resin used as a binder for impregnated board such as decorative board and plywood, and using kraft lignin (K), which is a natural product, in order to be able to cope with environmental issue can stably be produced.SOLUTION: Provided is a method for producing kraft lignin (K)-containing phenolic resin and which is a production method in which a solvent (S) compatible with water is added at any of each production stages, and in which, characterized, a solvent (s2) having a boiling point of less than 80°C is not used when reacting phenol (P) in a first stage and aldehyde (F).SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for stably producing a phenolic resin that is used as a binder for impregnated boards such as veneers and plywood, and that utilizes a natural product, kraft lignin (K), to deal with environmental problems. be.

In recent years, environmental problems have been widely recognized by the international community as important social issues. Under such circumstances, in the field of chemistry, development using natural products has been actively carried out.
Patent Literature 1 is a publication that provides a production method for obtaining modified cellulose in a hydrophobic medium such as an organic medium or a resin with less mechanical force, and a modified cellulose having easy defibration properties.
As described above, a number of publications have been published on the use of woody materials and herbaceous materials in biology as natural products.

Natural products other than cellulose include polylactic acid, polyamide, lignin and the like. Lignin is being studied as a filler for epoxy resin moldings and films. In the field of adhesives, lignin is being investigated for use as a filler for hot-melt adhesives. Also, since lignin is a high-molecular phenolic compound, its use in phenolic resin-based adhesives is under investigation.

JP 2021-006628 International publication 2016/098667 International publication 2017/163163

Patent Document 2 states in the abstract that "the impregnated plate includes a substrate and a resin composition impregnated into the substrate, and the resin composition contains a reaction product of lignin, phenols, and aldehydes. contains.”, which is a publication relating to an impregnated plate, a laminated plate and a resin composition. There is room for improvement in producing impregnated boards such as decorative board and plywood.
US Pat. No. 5,300,003 is a publication relating to liquid lignin compositions that are particularly useful in the production of resins for products such as thermal insulation, laminates, and engineered wood products such as oriented strand board (OSB). There is room for improvement in the methods of obtaining liquid lignin compositions.

To establish a method for stably producing a phenolic resin using kraft lignin (K), which is a natural product, used as a binder for impregnated boards such as veneers and plywood, so as to cope with environmental problems.

As a result of intensive studies by the inventors, a method for producing a kraft lignin (K)-containing phenolic resin, which is a production method in which a solvent (S) compatible with water is added in any of the production steps. , Kraft lignin (K)-containing phenolic resin characterized by not using a solvent (s2) with a boiling point of less than 80 ° C. when reacting the phenols (P) in the first step with the aldehydes (F). A manufacturing method was established.

Establishing a method for producing phenolic resin used as a binder for impregnated boards such as veneers and plywood, and establishing a method that can stably produce phenolic resin containing kraft lignin (K). It is possible to produce an impregnated board such as a decorative board, plywood, etc., which is easy to clean and excellent in terms of performance.

An example of a method for producing a kraft lignin (K)-containing phenolic resin used as a binder for impregnated boards such as decorative boards and plywood of the present invention is shown.

The kraft lignin (K)-containing phenolic resin of the present application is obtained by reacting phenols (P) and aldehydes (F) in the presence of an alkali catalyst (C), and adding a solvent (S) compatible with kraft lignin (K) and water. obtained by adding
Phenols (P) used in the present invention include, for example, phenol, cresol, xylenol, nonylphenol, para-tertiary-butylphenol, para-secondary-butylphenol, naphthol, catechol, resorcinol, hydroquinone, methylhydroquinone, dimethylhydroquinone, etc.
Kraft lignin (K)-containing phenolic resins used as binders for impregnated boards such as veneers and plywood are generally synthesized in multiple stages, and phenols (P) are preferably added in the first stage. .

As the aldehydes (F), any aldehydes (F) that can be used in the production of phenolic resins can be used.
For example, formaldehyde, paraformaldehyde, trioxane (metaformaldehyde) and the like can be used alone or in combination of two or more.
The amount of the aldehydes (F) added is more preferably F/P = 0.5 to 3.0 mol, where F is the number of moles of the aldehydes (F) and P is the number of moles of the phenols (P). is desirably used at a ratio of 1.0 to 2.5 mol.
Phenolic resins used as binders for impregnated boards such as veneers and plywood are generally synthesized in multiple stages, and the aldehydes (F) are preferably added in the first stage.

The catalyst (C) selected from alkali metals, alkaline earth metals, other metal hydroxides, and amine compounds used for reacting phenols (P) and aldehydes (F) is not particularly limited. For example, basic catalysts such as sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, magnesium hydroxide, trimethylamine, triethylamine, tributylamine and the like can be used as appropriate.
The added amount of the catalyst (C) selected from alkali metals, alkaline earth metals, other metal hydroxides, and amine compounds is 1 to 35 parts by mass with respect to 100 parts by mass of phenols (P). It is preferably 1.5 to 30 parts by mass.
The kraft lignin (K)-containing phenolic resin of the present application is generally synthesized in multiple stages, and the catalyst (C) selected from hydroxides of alkali metals, alkaline earth metals, other metals, and amine compounds is It is also possible to divide and put in each stage.

From the viewpoint of compatibility, kraft lignin (K) is desirably used as a phenol resin lignin used as a binder for impregnated boards such as decorative boards and plywood. Kraft lignin (K) is a material obtained by alkali-treating the lignin component contained in the pulp waste liquid of chemical pulping in the paper pulp manufacturing process. Materials obtained by acid treatment are commonly referred to as acid lignin.
The amount of kraft lignin (K) added is 1 to 250 parts by mass, more preferably 2 to 200 parts by mass, per 100 parts by mass of phenols (P).
Phenolic resin, which is used as a binder for impregnated boards such as veneers and plywood, is generally synthesized in multiple stages. can.
Kraft lignin (K) is commercially available from Stora Enso Oyj.

Kraft lignin (K)-containing phenolic resin used as a binder for impregnated boards such as decorative boards and plywood of the present application is added with a solvent (S) that is compatible with water in order to improve the solubility of kraft lignin (K). be done. However, if a solvent (s2) with a boiling point of less than 80°C is used in the reaction of the phenols (P) and the aldehydes (F) in the first step, the temperature in the reaction system does not rise and the phenol The performance of impregnated boards such as veneers and plywood deteriorates, probably because the molecular weight of the compound does not extend.
Solvents (s1) compatible with water having a boiling point of 80° C. or higher include hydrocarbon alcohols having 3 or more carbon atoms such as 2-propanol and n-butanol, diols such as ethylene glycol and ether compounds thereof, and acetonitrile. and nitriles such as propanenitrile.
Examples of the solvent (s2) compatible with water having a boiling point of less than 80° C. include alcohols such as methanol and ethanol, cyclic ether compounds such as tetrahydrofuran, and ketones such as acetone.
The amount of the solvent (S) compatible with water to be added is 5 to 350 parts by mass, more preferably 10 to 300 parts by mass, per 100 parts by mass of the phenol (P).
The solvent (S) compatible with water refers to a solvent having a solubility in water of 50 g/L or more at 20°C.

"When reacting the phenols (P) and the aldehydes (F) in the first step" refers to the time from the temperature at which the reaction is initiated until the reaction temperature is changed. Kraft lignin (K)-containing phenolic resin can also be made without changing the temperature, but in that case it is all the first step.

Kraft lignin (K)-containing phenolic resin used as a binder for impregnated boards such as decorative boards and plywood of the present application is the first stage after reacting phenols (P) with aldehydes (F). Urea and its derivatives, resorcinol, which reacts faster with formaldehyde than phenols (P), can be added to trap unreacted formaldehyde. The amount of these added is 0 to 40 parts by mass, more preferably 0 to 30 parts by mass, per 100 parts by mass of phenols (P).

Kraft lignin (K)-containing phenolic resin used as a binder for impregnated boards such as decorative board and plywood of the present application, when reacting phenols (P) in the first step with aldehydes (F), other natural products Alternatively, cashew shell oil, rosin or the like can be added.
A more preferable material is cashew oil, and among these, it is preferable to use refined cashew oil refined by distillation, solvent extraction, or the like, because the physical properties of decorative boards, plywood, etc. are easily stabilized.
The amount of refined cashew oil added is 0 to 50 parts by mass, more preferably 0 to 40 parts by mass, per 100 parts by mass of phenols (P). As a commercial product of refined cashew oil, product name: CX-1000 manufactured by Cashew Co., Ltd. can be mentioned.

The method of reacting the phenols (P) and the aldehydes (F) is not particularly limited. A method in which a catalyst (C) selected from group metals, hydroxides of other metals, and amine compounds is charged all at once and reacted, or a total amount of phenols (P) and a specified amount of alkali metals, alkaline earth metals, and other metals After charging the catalyst (C) selected from hydroxides and amine compounds of, the total amount of aldehydes (F) is added at a predetermined reaction temperature.

When reacting the phenols (P) in the first step with the aldehydes (F), the total amount of the phenols (P) and the total amount of the aldehydes (F), and the specified amount of alkali metal, alkaline earth metal, After adding the catalyst (C) selected from other metal hydroxides and amine compounds, the temperature outside the reaction vessel is preferably set to 80 to 105°C, more preferably 85 to 100°C. As mentioned above, if a solvent with a boiling point of less than 80° C. is used, the temperature in the reaction system cannot be raised sufficiently, so it is better not to use such a solvent.

After reacting the phenols (P) in the first step with the aldehydes (F), additional alkali metals, alkaline earth metals, other metal hydroxides, amine compounds, catalysts ( C), kraft lignin (K), and a water-compatible solvent (S) are added, and the reaction is preferably carried out at a set temperature outside the reaction vessel of 40 to 80°C, more preferably 45 to 75°C.

Kraft lignin (K)-containing phenol resin used as a binder for impregnated boards such as decorative boards and plywood is generally produced in two steps.

<Method for making decorative board>
Examples of the fibrous base material used for the decorative board include those made by using bleached and unbleached kraft pulps, sulfite pulps, and other wood pulps of softwoods, hardwoods, and other wood pulps alone or in combination. An inorganic fiber base material can also be used, and examples thereof include nonwoven fabrics and woven fabrics made of inorganic fibers such as glass fiber, rock wool, and carbon fiber.
A decorative board consists of a decorative layer and a core layer, as shown in FIG. For the core layer, a kraft lignin (K)-containing phenolic resin having a basis weight of 30 to 300 g/m2 of the fibrous base material is used, and in particular, the fibrous base material of 100 to 250 g/m2 is impregnated with the phenolic resin, and is heated at 100 to 140°C. A prepreg is made that is dried for 1-10 minutes.
Liquids used for the decorative layer include resin liquids containing thermosetting resins such as amino-formaldehyde resins, diallyl phthalate resins, and unsaturated polyester resins as main components. From the viewpoint of heat resistance and wear resistance, it is desirable to use an amino-formaldehyde resin. A prepreg is prepared by impregnating 30-300 g/m 2 decorative paper for decorative board with amino-formaldehyde resin and drying at 100-140° C. for 1-10 minutes.
A decorative board is obtained by stacking these and subjecting them to thermocompression molding using a press machine such as a flat plate press or a continuous press.

<How to make plywood>
5 plies of plywood will be described. It is made by laminating five veneers so that their fiber directions are perpendicular to each other. The veneers are called face/core/center core/core/back in order from the top. An adhesive for plywood is applied to both sides of the core using a spreader or the like, and laminated in the order of face/core/center core/core/back. When a plurality of sets are accumulated, they are stacked and cold-pressed at room temperature for several tens of minutes. After that, pressure is applied at 110 to 140° C. for several minutes for adhesion.

The present invention will be described in more detail below with reference to examples, comparative examples, test examples, and the like, but these are specific examples and are not intended to limit the invention in particular.

<Phenolic Resin Containing Kraft Lignin (K) Used as Binder for Decorative Board>
Method for producing phenolic resin of Example 1
Weigh 100 g of phenol, 115 g of 63%-kraft lignin aqueous solution, 138 g of 37%-formaldehyde aqueous solution, 10 g of 48%-sodium hydroxide, and 80 g of 2-propanol in a separable flask, set a lid and a stirring spring, Installed on the mantle heater. The set temperature of the mantle heater was set to 90° C., and the mixture was stirred for 1 hour. As a second step, the mixture was cooled to 70° C. and 5 g of urea was added to completely dissolve the urea.

Phenolic resin production methods of Examples 2 to 18 and Comparative Examples 1 to 4 Each material was added in the proportions shown in Tables 1 and 2, and the same method as the phenol resin production method of Example 1 was performed. 2 to 18 and Comparative Examples 1 to 4 were produced. Vanilex N is high-purity partially desulfonated sodium lignosulfonate manufactured by Nippon Paper Industries Co., Ltd. Sanex P321 is magnesium lignosulfonate manufactured by Nippon Paper Industries Co., Ltd.

Impregnability A fibrous base material of about 300 mm x 300 mm x 0.3 mm thickness with a basis weight of 200 g/m2 was immersed in a kraft lignin (K)-containing phenolic resin to confirm the impregnation. The case where the resin permeated the impregnated paper without any problem was evaluated as pass (: ◯), and the case where the resin did not permeate the impregnated paper was evaluated as disqualified (: ×). The results are shown in Tables 4-6. Among those that passed the test, those that were dried at 120° C. for 2 minutes became the prepreg of the core layer.

Exudation during Pressing Four pieces of core layer prepreg prepared in the manner described above were prepared. In Comparative Examples 3 and 4, impregnability was rejected, so no core layer prepreg was obtained.
Separately, an amino-formaldehyde resin was impregnated into a decorative paper for a decorative layer of about 300 mm × 300 mm × 0.1 mm thick with a basis weight of 120 g / m 2 fibrous base material, and dried at 120 ° C. for 2 minutes. A sheet of prepreg for the layer was prepared.
Four pieces of core layer prepreg and one piece of prepreg for decorative layer were superimposed and subjected to thermocompression molding under the conditions of 132°C, 5.9 MPa, and 60 minutes. ), the case where the resin protruded from the edge, and the case where the resin oozed out to the surface of the decorative layer were evaluated as disqualified (: x). Tables 3 and 4 show the results.

Boiling resistance test The boiling resistance test of the decorative board obtained according to paragraph 0025 of the decorative board was conducted according to JIS K-6902.
According to JIS K-6902 and JIS K-6903, a weight change rate of 17% or less is accepted, but in the present application, a rate of change of 10% or less is accepted, and a rate exceeding 10% is rejected.
Regarding the thickness change rate, JIS K-6902 and JIS K-6903 pass 19% or less, but in the present application, 15% or less was passed, and over 15% was rejected. Tables 3 and 4 show the results.

Warpage Warpage was measured immediately after molding and after 24 hours. When the decorative board was placed on a horizontal surface, the difference in height between the central portion and the edge was within 10 mm, which was judged as acceptable, and when it exceeded 10 mm, it was judged as unacceptable. As for the warp, there are cases where the decorative layer side is raised and cases where the decorative layer side is depressed, but Tables 3 and 4 show absolute values.

Using the phenolic resins of Examples 1 to 18 and Comparative Examples 1 to 4, impregnability, bleeding during pressing, boiling resistance test, and warpage evaluation were performed. Tables 3 and 4 show the results.

A method for producing a kraft lignin (K)-containing phenolic resin, which is a production method in which a solvent (S) compatible with water is added in any of the production stages, and the phenols (P) in the first stage and , Examples 1 to 18 in which the solvent (s2) with a boiling point of less than 80 ° C. was not used when reacting the aldehydes (F), impregnation, bleeding during pressing, boiling resistance test, All the warpages were passed.

Comparative Example 1, in which methanol, which is a solvent (s2) with a boiling point of less than 80°C, was used when the phenols (P) and aldehydes (F) in the first step were reacted. , the thickness change rate was rejected. Comparative Example 2, in which no kraft lignin (K) was used, failed in warpage after 24 hours.
Comparative Example 3 using Vanilex N, which is sodium ligninsulfonate of high purity, partial desulfonation, and Comparative Example 4, using Sanex P321, which is magnesium ligninsulfonate, failed in impregnation and could not produce a decorative board. I didn't. So-called acid lignin, but not kraft lignin (K), was shown to be poorly impregnable.

<Phenolic resin containing kraft lignin (K) used as a binder for plywood>
Method for producing phenolic resin of Example 19
100 g of phenol, 172.5 g of 37%-formaldehyde aqueous solution, 50 g of 48%-sodium hydroxide, 10 g of 2-propanol, and 65 g of water are weighed into a separable flask, a lid and a stirring spring are set, and a mantle heater is placed. installed. The set temperature of the mantle heater was set to 90° C., and the mixture was stirred for 1 hour. Next, the mixture was cooled to 70° C., 35 g of a 63%-kraft lignin aqueous solution was added, and the point of time when the kraft lignin was completely dissolved was taken as the end point.

Methods of producing phenolic resins of Examples 20-26 and Comparative Examples 5-6 Each material was added in the proportion shown in Table 5, and in the same manner as the method of producing phenolic resins of Example 19, Examples 20-26 , Comparative Examples 5 and 6 were produced.

The viscosity was measured according to JIS-Z-8803. The viscometer was a single cylindrical rotational viscometer manufactured by Shibaura Systems Co., Ltd., trade name: Vismetron VG-A1. Moreover, as a measurement condition, No. Measured at 2 rotors, 60 rpm, 60 seconds value, 23±1° C., and the measured value was taken as the viscosity. An appropriate viscosity range is 150 to 350 mPa·s.
Table 6 shows the results. In Comparative Example 5, although indicated by (*), the kraft lignin was not dissolved and the viscosity was not measured. Also, the following tests were not performed.

pH measurement Using HM-25H manufactured by Toa TKK Co., Ltd., pH was measured. A suitable pH range is 10.5 to 12.5.
Table 6 shows the results.

Gelation time Using an automatic gel timer manufactured by Elex Scientific Co., Ltd., product name: EX-790, 10 g of resin / 0.6 g of soda ash are mixed and dissolved in advance, and then 5.0 ± 0.1 g of the sample is 18 mmφ x 165 mm. and measured the gelation time at 90°C. A gelation time of 10 to 22 minutes is acceptable, and anything outside this range is unacceptable. Table 6 shows the results.

About 1.5 g of a sample was weighed into an aluminum pan having a non- volatile content diameter of 65 mm, a bottom diameter of 55 mm, a depth of 20 mm and a thickness of 0.05 mm to obtain the initial weight. An aluminum pan with a sample placed thereon was placed in a constant temperature layer previously adjusted to 105±1° C., and the dry weight after 3 hours was measured. The weight after drying was divided by the initial weight, and the non-volatile content was expressed as a percentage. A non-volatile content of 40-46% is acceptable, and anything outside this range is unacceptable. Table 6 shows the results.

Preparation of the composition of Example 19 100 g of the phenolic resin of Example 19, 22 g of water, 10 g of wheat flour, 23 g of calcium carbonate, and 5 g of sodium carbonate were weighed into a stirring vessel and equipped with stirring blades. The composition of Example 19 was obtained by stirring for 1 to 2 hours using Three-One Motor BL600, trade name.

Preparation of Compositions of Examples 20-26 and Comparative Example 6 Compositions of Examples 20-26 and Comparative Example 6 were prepared in the same manner as the composition of Example 19 was prepared.

5-ply plywood manufacturing method A larch with a thickness of 1.7 mm was selected for the face, center core, and back. The core was selected from Japanese cedar with a thickness of 3.6 mm. Face/core/center core/core/back were laminated with pressure so that the thickness was 12 mm. The moisture content of these materials is 6% or less, the area of each material is 300 mm x 300 mm, the temperature of each material is 23°C, and the working environment is 24°C.
The compositions of Examples 19 to 25 and Comparative Examples 5 to 6 were applied to both sides of the cedar wood as the core at 0.044 g/cm 2 , and the composition was face/core/center core/core/back. superimposed on Cold pressing was performed at 0.8 MPa for 20 minutes.
Next, a hot press was heated to 125.degree.
A vertical two-stage high-pressure press S2D-100 manufactured by Itsumi Co., Ltd. was used as a hot press.

Adhesion test A repeated steaming test was carried out according to the special standard of the Japanese Agricultural Standards for plywood. After immersing the test piece in water at room temperature for 2 hours or longer, it was steamed at 130±3° C. for 2 hours.
Next, it was immersed in running water at room temperature for 1 hour, and then steamed at 130±3° C. for 2 hours.
It was immersed in room temperature water, and after returning to room temperature, an adhesive strength test was performed in a wet state, the maximum load and wood fracture rate were measured, and the shear strength and average wood fracture rate were calculated. Based on this result, the pass rate was calculated.
The criteria for judgment are that a pass rate of 90% or more is pass (: ◯), and a pass rate of less than 90% is fail (: x). Table 6 shows the results.

A method for producing a kraft lignin (K)-containing phenolic resin, which is a production method in which a solvent (S) compatible with water is added in any of the production stages, and the phenols (P) in the first stage and , Examples 19 to 26, which were produced without using a solvent (s2) with a boiling point of less than 80 ° C. when reacting the aldehydes (F), had viscosity, pH, gelling time, nonvolatile matter, adhesiveness All tests passed.

In Comparative Example 5, in which the water-compatible solvent (S) was not used, the kraft lignin was not dissolved, and even the viscosity was not measured. Comparative Example 6, which did not use kraft lignin (K), failed the adhesion test.

FIG. 2 is a cross-sectional view of the configuration of the decorative board of the present invention.

1 Resin-impregnated decorative paper (decorative layer)
5 Resin-impregnated core paper (core layer)
9 Veneer

Claims (5)

A method for producing a kraft lignin (K)-containing phenolic resin,
A manufacturing method in which a solvent (S) compatible with water is added in any of the manufacturing stages,
Production of kraft lignin (K)-containing phenolic resin characterized by not using a solvent (s2) with a boiling point of less than 80 ° C. when reacting phenols (P) and aldehydes (F) in the first step Method. The method for producing a kraft lignin (K)-containing phenolic resin according to claim 1, wherein the kraft lignin (K) is 1 to 250 parts by mass with respect to 100 parts by mass of the phenol (P). The kraft lignin according to claim 1 or claim 2, wherein the ratio of the number of moles P of phenols (P) and the number of moles F of aldehydes (F) is F/P = 0.5 to 3.0. (K) A method for producing the phenolic resin containing. Any one of claims 1 to 3, wherein 1 to 35 parts by mass of a catalyst (C) selected from hydroxides of alkali metals, alkaline earth metals, other metals, and amine compounds is added to 100 parts by mass of phenols (P). A method for producing a kraft lignin (K)-containing phenolic resin according to . An impregnated board such as a decorative board or plywood made by using a phenolic resin as a binder, obtained by the method for producing a kraft lignin (K)-containing phenolic resin according to any one of claims 1 to 4.

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