JPH04300950A - Production of lignocellulose-phenolic resin having excellent high-temperature fluidity - Google Patents

Abstract

PURPOSE:To produce a lignocellulose-phenolic resin having excellent high- temperature fluidity by dissolving and solubilizing lignocellulose in a phenolic compound in the presence of a specific organic acid (anhydride) in combination with a strongly acidic catalyst. CONSTITUTION:A lignocellulose-phenolic resin having excellent high-temperature fluidity is produced by (1) dissolving and solubilizing a lignocellulose (e.g. wood flour and pulp) in a phenolic compound in the presence of a strongly acidic catalyst (e.g. mineral acid and Lewis acid) and one or more substances selected from acetic acid, maleic acid, itaconic acid, phthalic acid and their anhydrides, (2) converting the solubilized material into a resin optionally in the presence of a formaldehyde source, (3) adding a necessary amount of a filler (e.g. wood flour), a hardener (e.g. hexamethylenetetramine), a cure accelerator (e.g. calcium hydroxide), a cure-accelerator and water-acceptor (e.g. calcium oxide and magnesium oxide), a mold-releasing agent (e.g. zinc stearate), a pigment and, as necessary, a flame-retardant, etc., and (4) kneading the mixture.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a novel method for producing lignocellulose-phenolic resins. The lignocellulose-phenolic resin of the present invention is used as a molding material for compression molding, transfer molding, etc., for bonding silica sand (for shell molding),
It is useful as a powder binding material for binding abrasive grains (for grinding wheels).

0002

BACKGROUND OF THE INVENTION Novolac resins have been widely used as phenolic resins for molding materials and for binding silica sand or abrasive grains. This is synthesized by using an excess of phenol with respect to formaldehyde and using an acid as a catalyst. On the other hand, using a solution made by solubilizing and liquefying lignocellulose such as wood in phenol,
There is a method based on the idea of adding formaldehyde source substances such as hexamethylenetetramine, paraformaldehyde, and formalin and converting it into a resin to make a novolak resin-like material, and using the phenol-solubilized liquid of the lignocellulose as a direct reaction resin liquid. (Application number: Hei 1-179483). However, these resin compositions, especially those produced by acid-catalyzed solubilization, have a drawback in that the flow period before curing is too short, and improvement in thermal fluidity has been desired.

0003

SUMMARY OF THE INVENTION The present invention provides a novel method for producing lignocellulose-phenolic resin from a phenol-solubilized solution of lignocellulose such as wood. In other words, as part of the development of effective ways to use forest resources, which are renewable resources, we are developing a new lignocellulose-phenolic resin that can be sufficiently molded under practical molding conditions and has practical physical properties. The aim is to provide a manufacturing method.

0004

[Means for Solving the Problems] The gist of the present invention is to neutralize the solubilized material of lignocellulose such as wood into phenols, and then distill off unreacted phenols by vacuum distillation or the like to solidify at room temperature. In the case of novolac resin, fillers such as wood flour, hexamethylenetetramine (hardening agent), calcium hydroxide (hardening accelerator), zinc stearate (mold release agent), etc. When the mixture is added and mixed according to the conventional method, and brought to a high temperature of 100-odd degrees, there is almost no step in which it exhibits thermal fluid behavior, or it is insufficient to enable good hot-pressing molding or injection molding. As a countermeasure to the problem of hardening without taking a sufficient amount, when lignocellulose such as wood is solubilized with phenols in the presence of an acid catalyst and liquefied, an appropriate amount of acetic anhydride, acetic acid, maleic anhydride, maleic acid, etc. The present invention relates to a method for producing a lignocellulose-phenolic resin characterized by adding one or more organic acid anhydrides or organic acids such as acid, itaconic anhydride, itaconic acid, phthalic anhydride, and phthalic acid.

In particular, when a strong acid catalyst is used to solubilize lignocellulose in phenols, if an appropriate amount of the organic acid anhydride or organic acid is present, the lignocellulose component is reduced in molecular weight as a result of solubilization. Phenolization takes place, which competes with phenol for some of the above reaction sites, resulting in a more appropriate final three-dimensional curing rate, and the acyl groups introduced along with them compete with phenol. It is noteworthy that the thermoplasticity and thermal fluidity of the cellulose-phenolic resin are improved.

[0006] The lignocellulose used in the method for producing the lignocellulose-phenolic resin molded product of the present invention includes wood flour, wood fiber (pulp), wood chips, unused lignocellulose such as oil palm tree trunks and coconut shells, bagasse, Bark, rice straw, etc. are used.

[0007] Phenols used in the present invention include phenol, cresol, xylenol, resorcinol, and alkylresorcinol. When lignocellulose is solubilized in phenols, the intramolecular bonds of lignin, cellulose, and hemicellulose, which are the main components of lignocellulose, are cleaved to various degrees, and the phenols are converted to various degrees into each of the cleaved components. has been introduced to facilitate dissolution, improve the performance and properties of the solution, and increase the reactivity of lignocellulose constituents such as lignin. In other words, cellulose and hemicellulose undergo hydrolysis and dehydration reactions during this process, resulting in low-molecularization and phenolization in the direction of hydroxymethylfurfural and furfural production, and lignin also undergoes its own unique low-molecularization and phenolization. As a result, all components of wood are converted into highly reactive substances.

[0008] Such a reaction can be carried out simply by heating without a catalyst, since wood originally contains resin acids and also has an acetyl group as a pendant group in its constituent components that easily hydrolyzes to produce acetic acid. It can also be done by doing this, but in this case a fairly high temperature of 200-270°C is required. In order to make such reactions such as hydrolysis, dehydration, and phenolization occur more easily, mineral acids such as sulfuric acid and hydrochloric acid, organic acids such as toluenesulfonic acid and phenolsulfonic acid, aluminum chloride, zinc chloride, and trifluoride are used. The presence of an acid such as a Lewis acid such as boron is effective. In the presence of acid, solubilization of lignocellulose in phenol is also possible in a reaction at 150°C. However, there is a difference in the solubilized product between non-catalytic liquefaction and acid-catalyzed liquefaction, with the latter introducing five times as much phenol depending on the conditions. We must take these into account when considering the use of these solubilized and liquefied products.

When lignocellulose having such characteristics is solubilized and dissolved in phenols, organic acid anhydrides such as acetic anhydride, acetic acid, maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, phthalic anhydride, phthalic acid, etc. When one or more types of phenol or organic acids are added, as mentioned above, they partially compete with phenolization, make the degree of introduction of phenol into the low molecular weight lignocellulose component more appropriate, and complete curing. In addition to delaying the time required for this by an appropriate amount, the lignocellulose-phenolic resin is given the effect of internal plasticization due to the introduction of acyl groups.

[0010] In the present invention, the lignocellulose obtained as described above is converted into a novolac resin by phenol-solubilizing the lignocellulose, and in this case, the acidity of the solubilized product is utilized. That is, paraformaldehyde, formalin, and hexamethylenetetramine are added to the lignocellulose-phenol solubilized material as formaldehyde so that the molar ratio is 1 or less relative to the calculated amount of phenol in the system, and the reaction temperature is set to about 80°C. - Allow to react for 40 minutes (in some cases, it may not react at all). however,
Those that do not react with formaldehyde at all can also be usefully used for novolac resin applications.

The resin solution or lignocellulose-phenol solubilized product itself obtained in this manner is first neutralized and operated to form a powder at room temperature. The resulting powdered product can be used as more than a novolac resin precondensate. That is, this powdered product is treated with wood flour, wood fibers (pulp), lignin or lignin compounds, synthetic fibers, and inorganic substances such as silica, diatomaceous earth, glass, alumina, mica, carbon black, and silicon carbide. 20-70% by weight of the total as filler
In addition, the required amount of a curing agent such as hexamethylenetetramine is added.

[0012]Additives further include, if necessary, reinforcing agents such as alkylresorcinol; crosslinking agents such as polyvalent isocyanate compounds and polyvalent epoxy compounds; hardening accelerators such as calcium oxide, magnesium oxide, and calcium hydroxide; pigments; and flame retardants. ;Add a lubricant such as stearic acid or calcium stearate. For mixing, a mixer with a kneader-type structure having a ribbon-type rotary blade and a jacket on the outside, a Banbury mixer, etc. is used, and for kneading, a screw extrusion-type kneader, a co-kneader, a heating roll, a ball mill, etc. are used. I can do it.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

[0014]

[Reference Example 1] 15 g of a normal novolac resin molding material was introduced into a torque rheometer [manufactured by Toyo Seiki Co., Ltd., equipped with Laboplasto Mill; 30 ml capacity], and the temperature was set at 120°C and 30 rpm.
Figure 2 shows the results of measuring thermal flow and curing behavior under the following conditions, with a full scale of 1000 kg cm and a chart speed of 6 cm/min (6 divisions/min). However, this novolak resin molding material is obtained by kneading and mixing hexamine, wood flour, hardening accelerator (calcium hydroxide), and mold release agent with novolac initial condensate powder at 70°C.

[0015]

[Reference Example 2] 20 g of phenol and 1 g of sulfuric acid were added to 10 g of cedar wood flour (approximately 80 mesh) and heated under reflux at 150° C. for 30 minutes under normal pressure. Immediately after heating, approximately 1.8 g of barium hydroxide (octahydrate) was added to neutralize the mixture, and free phenol was removed at 150° C. under reduced pressure (approximately 10 mmHg) for approximately 60 minutes. Thereafter, the mixture was allowed to cool and the residue was ground in an iron mortar to obtain about 25 g of a blackish brown powder. 78 parts of the powder thus obtained were thoroughly mixed with 16 parts of hexamine, 4 parts of calcium hydroxide as a hardening accelerator, and 2 parts of zinc stearate as an internal mold release agent. 150 mesh pass) at a ratio of 5:5 (in a mortar), 15 g of the mixture was introduced into a torque rheometer, and the thermal flow and hardening behavior was measured under the same conditions as in Reference Example 1. show. From FIG. 3, in the case of this composition,
It can be seen from a comparison with FIG. 2 that the heat flow region is extremely short and the curing time is extremely short.

[0016]

[Example 1] Wood flour was solubilized and liquefied in phenol under the same conditions as in Reference Example 2, except that 0.5 g (4.9 x 10-3 mol) of acetic anhydride was further added, and then neutralized and untreated. The reaction phenol was distilled off and the mixture was ground to obtain a dark brown powder. Thereafter, in the same manner as in Reference Example 2, hexamine, calcium hydroxide, zinc stearate and wood flour were mixed, 15 g of the mixture was introduced into a torque rheometer, and heated under the same conditions as in Reference Examples 1 and 2. Figure 4 shows the results of measuring flow and hardening behavior. It can be seen from FIG. 4 that the curing time is somewhat longer than the results shown in FIG.

[0017]

[Example 2] The amount of acetic anhydride added was 5 g (49 x 10-3
A wood-phenolic resin molding material was obtained under the same conditions as in Example 1 (Reference Example 2), except that the amount of mol) was used, and the thermal flow and curing behavior was measured under the same conditions. The results are shown in FIG. From Figure 5,
In this case, it is clear that the melting curve, melt viscosity and curing curve are all typical, and the curing time is similar to that of the commercially available novolak resin in FIG. Furthermore, it is a predictable result that a wood-phenolic resin molding material exhibiting a thermal flow/hardening curve close to that shown in FIG. 2 can be obtained.

[0018]

[Example 3] A wood-phenolic resin molding material was obtained under the same conditions as in Examples 1 and 2 (originally Reference Example 2) except that 10 g of acetic acid was used instead of acetic anhydride, and heated under the same conditions. The flow and hardening behavior was measured and the results are shown in FIG. Figure 6
First of all, it is known that the curing time is extremely long, and the profile is such that it is difficult to judge whether curing has occurred properly in the first place. It can be expected that the acetylation is the most advanced compared to Examples 1 and 2, and the thermal fluidity is increased, while on the other hand, the amount of bound phenol is the least among the three. In other words, it can be seen that there is less bound phenol and the torque during curing is smaller. It can be said that excessive use of acetic acid is not necessarily good for the purpose of producing molding materials.

[0019]

[Effects of the Invention] As described above, the lignocellulose-phenolic resin of the present invention has almost the same thermal fluidity as ordinary phenolic resin, and it is possible to provide a molding material with excellent workability. Became.

[0020]

[Brief explanation of drawings]

FIG. 1 shows a thermosetting behavior diagram of a thermosetting resin measured by a torque rheometer (30 ml capacity equipped with Labo Plastomill manufactured by Toyo Seiki).

FIG. 2 shows the thermosetting behavior of a molding material using a common phenolic novolak resin.

FIG. 3 shows the thermosetting behavior of phenolic resin-like molding materials from catalytically solubilized wood.

FIG. 4 shows the thermosetting behavior of a phenolic resin-like molding material made from a wood liquefied product obtained by solubilizing it by adding a small amount of acetic anhydride.

FIG. 5 shows the thermosetting behavior of a phenolic resin-like molding material made from a liquefied wood product obtained by solubilizing it by adding a nearly appropriate amount of acetic anhydride.

FIG. 6 shows the thermosetting behavior of a phenolic resin-like molding material made from a wood liquefied material obtained by solubilizing it by adding a seemingly excessive amount of acetic acid.

Claims (1)

[Claims] Claim 1: When lignocellulose is dissolved and solubilized in phenols in the presence of a strong acidic catalyst such as a mineral acid or a Lewis acid, acetic anhydride, acetic acid, maleic anhydride, maleic acid,
One or more organic acid anhydrides or organic acids such as itaconic anhydride, itaconic acid, phthalic anhydride, and phthalic acid are allowed to coexist, and the resulting solubilized product is made into a resin either directly or by adding a formaldehyde source. , a filler such as wood flour in the required amount, a hardening agent such as hexamethylenetetramine, a hardening accelerator such as calcium hydroxide, a hardening accelerator/moisture scavenger such as magnesium oxide and calcium oxide, and a mold release agent such as zinc stearate. A method for producing a lignocellulose-phenol resin with excellent thermal fluidity, which is made by blending a phenolic resin, a pigment, and if necessary a flame retardant.