JP2002327034A - Method for producing resorcin-lower aldehyde resin aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a resorcin-lower aldehyde resin aqueous solution in which the resorcin content is reduced without adding the third component such as phenols and organic solvents or the like in the production method of the solution obtained by the condensation polymerization of resorcin and lower aldehyde such as formaldehyde in an aqueous solution. SOLUTION: The method with reduced resorcin content is characterized in that a crude aqueous solution containing a resorcin-lower aldehyde resin and resorcin is subjected to the membrane separation with a semi-permeable membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a resorcinol / lower aldehyde resin aqueous solution having a reduced resorcinol content.

[0002]

2. Description of the Related Art Conventionally, resorcinol / lower aldehyde resin is known as a resin obtained by polycondensation of resorcinol and a lower aldehyde such as formaldehyde in an aqueous solution. Widely used for agents, adhesives and adhesion promoters. For example,
By kneading resorcinol-formaldehyde resin, which is one of the above resins, into rubber, the adhesiveness between the obtained rubber composition and fibers can be improved. However, if the amount of unreacted resorcinol present in the resin is large, it may cause a bloom phenomenon on the rubber surface, or cause contamination of the working environment and equipment due to evaporation of unreacted resorcinol during kneading of the rubber. There is a need for a method for producing an aqueous resorcinol / lower aldehyde resin solution having a reduced content of resorcinol.

[0003]

Under these circumstances, as a method for reducing the resorcinol content in a crude aqueous solution of resorcinol / lower aldehyde resin, for example, Japanese Patent Application Laid-Open No.
-115413 and JP-A-10-316735
Japanese Patent Application Laid-Open No. 57-143316 discloses a method of adding phenols such as hydroxybenzaldehyde and an alkyl-substituted phenol to a crude aqueous solution of resorcinol / lower aldehyde resin.
A method for extracting resorcinol by adding an organic solvent to a lower aldehyde resin is disclosed. However, in these methods, phenols, organic solvents, and the like have to be added as the third component. The purpose of the present invention is
An object of the present invention is to provide a method for producing a resorcinol / lower aldehyde resin aqueous solution having a reduced resorcinol content without adding a third component such as a phenol or an organic solvent.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied a method for producing a resorcinol / lower aldehyde resin from a crude aqueous solution. The present inventors have found that a resorcinol / lower aldehyde resin aqueous solution having a reduced resorcinol content can be obtained without adding a third component, thereby completing the present invention. That is, the present invention relates to a method for producing a resorcinol / lower aldehyde resin aqueous solution having a reduced resorcinol content, characterized in that a crude aqueous solution containing a resorcinol / lower aldehyde resin and resorcinol is subjected to membrane separation with a semipermeable membrane. is there.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. With the resorcinol / lower aldehyde resin of the present invention,
It is obtained by condensation polymerization of resorcinol and lower aldehyde in an aqueous solution, and is a resin having a molecular weight distribution of about 2 to 5 nuclei. Here, the n nucleus represents a resorcinol / lower aldehyde resin having n resorcinol nuclei.
A method for producing a crude aqueous solution containing a resorcinol / lower aldehyde resin and resorcinol used in the present invention (hereinafter referred to as a crude aqueous solution) includes, for example, an acid such as oxalic acid, phosphoric acid, sulfuric acid, hydrochloric acid, and P-toluenesulfonic acid. In the presence of a catalyst,
Method of condensation polymerization of resorcinol and lower aldehyde in aqueous solution, method of addition polymerization of lower aldehyde to resorcinol in the presence of an alkali catalyst such as sodium hydroxide and potassium hydroxide to form methylol, and then dehydration in the presence of an acid catalyst Is mentioned. Among them, a method in which condensation polymerization is performed in the presence of an acid catalyst is preferable.

The lower aldehyde used in the present invention includes, for example, aldehydes having about 1 to 4 carbon atoms, such as formaldehyde, acetaldehyde, n-butyraldehyde, glyoxal, glutaraldehyde, glyoxylic acid and paraformaldehyde. Among them, formaldehyde, acetaldehyde and paraformaldehyde are preferred, and formaldehyde is particularly preferred.

The method of polycondensation in the presence of an acid catalyst will be described in more detail. The amount of the acid catalyst used is generally about 0.05 to 10 mol%, preferably 0.1 to 5 mol%.
Mol%. The reaction temperature in the polycondensation is usually about 20 to 100 ° C, and among them, a method of gradually increasing the temperature during the reaction is preferable. The reaction order is, for example, a method of adding an acid catalyst to a resorcinol aqueous solution and then adding a lower aldehyde aqueous solution, a method of adding an acid catalyst to a lower aldehyde aqueous solution and then adding resorcinol, an aqueous solution of resorcinol and a lower aldehyde And a method of adding an acid catalyst to the mixture.

The molar ratio of resorcinol to lower aldehyde in producing a crude aqueous solution is usually 1 to 5 per mole of aldehyde group of lower aldehyde.
It is about mol, preferably 1.5 to 3 mol. In the production of the crude aqueous solution of resorcinol / lower aldehyde resin, phenols such as phenol, cresol and xylenol may be used in combination, but it is preferable that phenols are not substantially used in combination.

The crude aqueous solution of resorcinol / lower aldehyde resin thus obtained varies depending on the molar ratio of resorcinol / lower aldehyde resin, but usually has a weight average molecular weight of about 300 to 1,000 and a number average molecular weight of about 200 to 800. -Contains a lower aldehyde resin. The unreacted resorcin content in the crude aqueous solution varies depending on the molar ratio of resorcin / lower aldehyde, but is usually about 15 to 40 parts by weight based on 100 parts by weight of the solid content of resorcin / lower aldehyde resin. The solid content in the present invention means resorcinol / lower aldehyde resin; raw materials of the resin such as resorcinol and lower aldehyde; intermediates and by-products derived from the raw materials.

The crude aqueous solution of resorcinol / lower aldehyde resin may contain a solvent such as alcohols such as methanol, ethanol and isopropanol. The pH of the crude aqueous solution of resorcinol / lower aldehyde resin is usually about pH 3 to 9, and among them,
In order to increase the permeation flux, the pH is preferably about 5 to 8, particularly preferably about 6 to 7.5.

The method for producing a resorcinol / lower aldehyde resin aqueous solution of the present invention is a method of separating a crude aqueous solution of resorcinol / lower aldehyde resin through a semipermeable membrane, and specifically includes a dialysis method and a permeation method. Can be Examples of the dialysis method include, for example, a method in which water or the like is present on the opposite side through a dialysis membrane of a crude aqueous solution of resorcinol / lower aldehyde resin and the low molecular weight component is dialyzed toward the water side. A method in which water is added to discharge low-molecular-weight components through a dialysis membrane may be used.

As the permeation method, for example, a nanofiltration separation membrane, a reverse osmosis membrane, an ultrafiltration membrane, or the like is used as a semipermeable membrane, and a reverse osmosis method in which low molecular weight components are separated by applying pressure to one side of the membrane. An ultrafiltration separation method and the like can be mentioned. Among the methods of membrane separation using a semipermeable membrane, a permeation method in which pressure is applied to about 0.1 to 5 MPa is preferable. At this time, the solid concentration of the crude aqueous solution of resorcinol / lower aldehyde resin is usually 1 to 5
It is about 0%. Further, water may be discharged from the semipermeable membrane together with the low molecular weight component to raise the solid content concentration of the aqueous solution to a desired concentration.

When the crude aqueous solution of resorcinol / lower aldehyde resin is subjected to membrane separation, a method of adding water is preferable, and a method of continuously adding water to perform membrane separation is particularly preferable. The amount of water added here is generally about 10 times or less, preferably about 5 times or less, of the total weight of the crude aqueous solution used for the resorcinol / lower aldehyde resin. It is preferable that the amount of water to be added is 10 times or less, since the time required for membrane separation tends to be short. In addition, in the method of membrane separation by continuously adding water, the solid concentration of the crude aqueous solution of resorcinol / lower aldehyde resin during the treatment is usually about 5 to 50% by weight, especially about 10 to 30% by weight. It is preferable to adjust the rate of addition of water so that the amount of water is reduced. When the solid content concentration is 50% by weight or less, the viscosity of the crude aqueous solution of resorcinol / lower aldehyde resin tends to decrease and the separation speed tends to improve, which is preferable. Further, even when the solid content concentration is 5% by weight or more, the separation speed tends to be improved, which is preferable.

As the semipermeable membrane used for the membrane separation, polymer materials such as natural, synthetic, semisynthetic and the like are usually used. Specifically, cellulose, acetylated cellulose, polypropylene, polystyrene, polyacrylonitrile, Examples thereof include polyfluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, polyester, polycarbonate, polysulfone, polyethersulfone, polyamide, and polyimide. Among them, polyacrylonitrile, polyvinylidene fluoride, polysulfone, polyether sulfone, polyamide, polyimide and the like are preferable. Examples of the form of the semipermeable membrane include an asymmetric / porous phase change film, an asymmetric phase change film, a composite film, a stretched film, a sintered film, and a track erosion film. Among them, preferred are an asymmetric / porous phase change membrane, an asymmetric phase change membrane, and a composite membrane.

When the membrane is separated using a 0.25% by weight aqueous sodium sulfate solution under normal pressure at a pressure of 2 MPa until a steady state is reached, the following formula (1) R = [1- (Cp / 0.25)] × 100 (1) (wherein, R represents the rejection of the semipermeable membrane [%], and Cp is the concentration of sodium sulfate in the permeate obtained by membrane separation with the semipermeable membrane [% by weight]. The rejection ratio R calculated by the formula is 3
A semi-permeable membrane of about 5 to 99% is preferred,
Those having about 5 to 99% are suitable.

As the semipermeable membrane, for example, a polyethersulfone semipermeable membrane SNKCEA, SNKCEB, a polyamide semipermeable membrane D-5 series, NF-45, TS-40, T
S-80, TFC-4921S, ATF-50, ATF
-60, G-5, G-10, G-20, NF-70, N
F-90 (above, obtained from Sanko Co., Ltd.), polyamide-based semipermeable membrane SU-600 (manufactured by Toray), polyacrylonitrile-based semipermeable membrane MPS-34, MPS-44 (above, obtained from Nippon Abuco Co., Ltd.) ), Polysulfone semipermeable membrane NT
A commercially available semipermeable membrane such as R-7450 (manufactured by Nitto Denko) can be used.

[0017] The membrane separation is usually carried out at a temperature of about 10 to 70 ° C, preferably 20 to 60 ° C. When the temperature of the membrane separation is 10 ° C. or higher, the separation speed tends to be improved, and when the temperature is 70 ° C. or lower, the durability of the semipermeable membrane tends to be improved.

The membrane separation device used in the present invention includes:
For example, a membrane separation device having a shape such as a total filtration type filtration type or a cross flow type filtration type may be used.

The aqueous solution of the resorcinol / lower aldehyde resin thus obtained usually has a solid concentration of about 5 to 50% by weight, and may be diluted or evaporated and concentrated as required.
The evaporation and concentration can be performed under normal pressure or under reduced pressure, but is preferably performed at about 98 to 102 ° C. under normal pressure. Further, the aqueous solution of resorcinol / lower aldehyde resin may be used, if necessary, with an acid such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, or acetic acid, or a base such as ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, or barium hydroxide. In addition, the pH is adjusted to about 2 to 5, preferably about 3 to 4.

When producing a crude aqueous solution of resorcinol / lower aldehyde resin, resorcinol contained in a permeate obtained by membrane separation may be used as a raw material. At this time, the resorcinol may be concentrated by distilling the permeate to be used, or the resorcinol may be concentrated by membrane separation. As a specific method of the membrane separation, a method similar to the above-mentioned membrane separation is exemplified, except that the semipermeable membrane used has a fractionation molecular weight of less than about 2,000.

The aqueous solution of resorcinol / lower aldehyde resin thus obtained can be used as it is for additives, adhesives and adhesion promoters. When it is preferable to reduce the amount of water such as an additive to the rubber composition, the amount of water can be reduced by a method such as concentration by distillation or concentration by membrane separation.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The parts and percentages in the examples are on a weight basis unless otherwise specified.

(Measurement of resorcinol content) A sample whose resorcinol content was to be determined was dissolved in THF (tetrahydrofuran), and the THF layer was filtered through a 0.45 μmφ disk filter for THF insoluble matter. Next, THF is used as a mobile phase,
GPC equipped with an RI detector (measured by gel permission chromatogram, and the peak area percentage of resorcinol in all peaks excluding peaks such as solvents from the obtained peaks was determined based on the resorcinol content ( %) And the remainder was determined as the content of polynuclear bodies (resorcinol-formaldehyde resin containing two or more resorcinol nuclei.) On the other hand, the solid content was determined from the content of water as a solvent, and this solid content was determined. The resorcinol content (%) and the polynuclear content (%) in the sample were determined from the above ratios to the solid content.

(Example of measurement of rejection ratio R)
150 parts of an aqueous solution containing 25% was subjected to a molecular weight cut-off of 2,500.
Using an all-filtration type filtration device (trade name: RO-3 type reverse osmosis / ultrafiltration tester, manufactured by NGK Flutec Co., Ltd.) equipped with a semipermeable membrane (ultrafiltration membrane made of aromatic polyamide) Room temperature, 2M
Filtration is performed under a pressure of Pa until the concentration of the permeate no longer increases.
Part, aqueous solution containing 0.37% sodium sulfate 100
Got a part. That is, 0.9% of sodium sulfate was permeated into the permeate with respect to 100% of sodium sulfate contained in the crude aqueous solution, and the rejection R was R = [1- (0.007 / 0.25)] × 100 = 97 0.2%.

(Production Example 1 of Aqueous Solution Containing Resorcinol / Lower Aldehyde Resin) Resorcinol: 100 parts, water: 35 in a flask equipped with a stirrer, a thermometer, and a dropping funnel.
Parts, p-toluenesulfonic acid dihydrate: 0.06 parts, and stirred at 45 ° C until completely dissolved. Then 37
% Formaldehyde aqueous solution: 29 parts was added dropwise at 45 to 100 ° C. After dropping, keep at 98-100 ° C for 2 hours.
Stirred. After cooling, Radiolite # 700: 3 parts were mixed and stirred. Thereafter, the radiolite was filtered off, the filtrate was neutralized with a 5% aqueous sodium hydroxide solution: 0.2 part, and the resulting reaction product solution was concentrated at 105 ° C. under normal pressure to give a solid content of 62%. An aqueous solution containing a resorcinol-formaldehyde resin having a pH of 3.0 was obtained. When this aqueous solution was measured by GPC, resorcinol: 33
%, Polynuclear: 67%. (Production Example 2 of aqueous solution containing resorcinol / lower aldehyde resin) In a flask equipped with a stirrer, a thermometer, and a dropping funnel, resorcinol: 100 parts, water: 33.3 parts, p-
Toluenesulfonic acid dihydrate: 0.06 parts are mixed,
The mixture was stirred at 45 ° C. until completely dissolved. Thereafter, 35.4 parts of a 37% aqueous formaldehyde solution was added dropwise at 45 to 100 ° C. After completion of the dropwise addition, the mixture was kept warm and stirred at 98 to 100 ° C for 2 hours. After the heat retention, 30% aqueous sodium hydroxide solution:
0.4 parts were charged. After cooling, radio light # 700:
The three parts were mixed and stirred. Thereafter, an aqueous solution containing a resorcin-formaldehyde resin having a solid content of 63% was obtained by filtering the radiolite. This aqueous solution is
As measured by PC, resorcinol: 24%, polynuclear body: 76%.

(Example 1) The aqueous solution containing the resorcinol-formaldehyde resin obtained in Production Example 1 was diluted and adjusted by adding water to a solid content of 20%. 1000 parts were obtained. The aqueous solution was subjected to a permeation flux of 3.7 L at room temperature and under a pressure of 3 MPa using a total filtration filter equipped with the semipermeable membrane having a rejection of 97.3% against an aqueous solution containing 0.25% of sodium sulfate. / m ² / hr for 5 hours, filtered 370 parts permeate containing 12% resorcinol, 25% resorcinol
630 parts of an aqueous solution of a resorcinol-formaldehyde resin containing That is, 21.5% of resorcinol permeated into the permeate with respect to 100% of resorcinol contained in the crude aqueous solution.

Examples 2 to 4 Water and caustic soda were added to the aqueous solution containing the resorcinol-formaldehyde resin obtained in Production Example 1 to obtain a solid content of 20% and a pH shown in Table 1. Was adjusted as follows. Filtration was performed for 5 hours at the permeation flux shown in Table 1 according to Example 1, and the obtained permeate was measured by GPC, and the “content of resorcinol contained in the permeate” was measured. I asked. Table 1 shows the result of expressing the content of resorcinol contained in the obtained permeate relative to the amount of resorcinol contained in the crude aqueous solution as “resorcinol transmittance to the permeate”.

[0028]

[Table 1]

(Example 5) Solid content concentration as in Example 1
To 1000 parts of a crude aqueous solution of resorcinol / formaldehyde resin adjusted to 20% and pH 3.0, using a polyethersulfone ultrafiltration membrane having a rejection rate R of 38.4% for a 0.25% by weight aqueous sodium sulfate solution at room temperature and 3 MPa Under pressure,
The permeation flux was filtered at 2.5 L / m ² / hr to obtain 250 parts of a permeated liquid containing 14% of resorcin and 750 parts of an aqueous solution of a resorcin-formaldehyde resin containing 22% of resorcin. That is, the resorcinol permeability to the permeate is 17.
5%.

Examples 6 to 13 Water and caustic soda were added to the aqueous solution containing the resorcinol-formaldehyde resin obtained in Production Example 2 to obtain a solid content of 20% and a pH of Table 2.
The pH was adjusted to the value described in (1). Filtration was performed in Example 1.
Filtration was performed at the permeation flux shown in Table 2 for 5 hours according to the above, and the obtained permeate was measured by GPC to determine “the content of resorcinol contained in the permeate”. Table 2 (Examples 6 to 13) shows the result of expressing the content of resorcinol contained in the obtained permeate with respect to the amount of resorcinol contained in the crude aqueous solution as "resorcinol transmittance to the permeate".

[0031]

[Table 2]

[0032]

As shown in the Examples, the resorcinol / lower aldehyde resin aqueous solution with reduced resorcin content can be obtained by the production method of the present invention.
The obtained aqueous solution or a resorcinol / lower aldehyde resin obtained by concentrating the aqueous solution may be used as an adhesive for organic fibers and wood, a curing agent for epoxy resin, an additive to phenolic resin and rubber, and an adhesion promoter. It can be used as an agent. And, from these adhesives, additives, curing agents, adhesion promoters and the like, resorcinol can be prevented from evaporating due to heating or the like. Furthermore, blooming of resorcinol can be suppressed from the rubber composition containing the resorcinol / lower aldehyde resin of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Morio Yamamoto 3-1-198, Kasuganaka, Konohana-ku, Osaka City Within Sumitomo Chemical Co., Ltd. (72) Inventor Masahiko Kurumaya 3-chome, Kasuganaka, Konohana-ku, Osaka-shi No. 1 98 Sumitomo Chemical Co., Ltd. F-term (reference) 4D006 GA03 GA06 KA17 MB05 MB06 MC11 MC22 MC39 MC48 MC49 MC54 MC58 MC62 PA02 PB15 PB70 4J033 CA01 CA13 CD03 CD05

Claims (10)

[Claims] 1. A method for producing a resorcinol / lower aldehyde resin aqueous solution having a reduced resorcinol content, comprising separating a crude aqueous solution containing a resorcinol / lower aldehyde resin and resorcinol with a semipermeable membrane. 2. The method according to claim 1, wherein the crude aqueous solution of resorcinol / lower aldehyde resin has a pH of 3 to 9. 3. When the semipermeable membrane is subjected to membrane separation using a 0.25% by weight aqueous sodium sulfate solution, the following formula (1) R = [1- (Cp / 0.25)] × 100 (1) Represents the rejection [%] of the semipermeable membrane, and Cp represents the concentration [wt%] of sodium sulfate in the permeate obtained by membrane separation with the semipermeable membrane.) 3
The method according to claim 1 or 2, wherein the membrane is a 5-99% semipermeable membrane. 4. The method according to claim 1, wherein the semipermeable membrane is an ultrafiltration membrane or a reverse osmosis membrane. 5. The method according to claim 1, wherein the membrane separation in the semipermeable membrane is performed under a pressure of 5 MPa or less. 6. The method according to claim 1, wherein the membrane separation is carried out while adding water so that the solid content of the crude aqueous solution of resorcinol / lower aldehyde resin is 5 to 50% by weight. The production method according to any one of the above. 7. The method according to claim 1, wherein the membrane is separated by a total filtration type or cross-flow type filtration type membrane separation device.
7. The method according to any one of items 1 to 6, above. 8. The method according to claim 1, wherein the crude aqueous solution of resorcinol / lower aldehyde resin is an aqueous solution obtained by polycondensation in the presence of resorcinol, lower aldehyde and an acid catalyst. Production method. 9. The crude aqueous solution of resorcinol / lower aldehyde resin is a crude aqueous solution prepared by using resorcinol contained in a permeate separated by a semipermeable membrane as a raw material. The production method according to any one of the above. 10. The method according to claim 1, wherein the resorcinol / lower aldehyde resin is a resorcinol / formaldehyde resin.