JPH08165313A - Method of removing metal from vinylphenol polymer - Google Patents

Abstract

PURPOSE: To remove various metals from a polymer inexpensively at good efficiency by passing a solvent solution of a vinylphenol polymer through a filter in which a zeta potential generates owing to the action of a cationic charge modifier. CONSTITUTION: A cationic charge modifier is added to a filter medium made of a particle component such as diatomaceous earth or activated carbon and a fiber component such as pulp or cellulose acetate to prepare a filter. This filter is given a cationic charge by the cationic charge modifier and therefore generates a zeta potential between itself and the charged substance in the liquid passing the filter. A solution prepared by dissolving a vinylphenol polymer (e.g. poly-p-phenylvinylphenol) in a solvent (e.g. propylene glycol monomethyl ether acetate) is passed through this filter, whereupon, various metallic impurities such as alkali metal, alkaline earth metal or trasition metal contained in the vinylphenol polymer can be easily removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinylphenol polymer, that is, a homopolymer of vinylphenol, a copolymer of vinylphenol and another comonomer, or a modified product or derivative thereof in a solution state. The present invention relates to a method of removing contained metals such as sodium, iron, and calcium by passing through.

[0002]

As a method for producing vinylphenol, a method of dehydrating acetoxyphenylmethylcarbinol,
Known methods include decarboxylation decomposition of hydroxycinnamic acid and dehydrogenation of ethylphenol. It is also known to obtain a vinylphenol polymer by homopolymerizing or copolymerizing the vinylphenol monomer obtained by these methods in the presence of a cation or radical polymerization initiator with another comonomer. Furthermore, a method for producing a modified product excellent in light transmittance by hydrogenating these vinylphenol polymers (JP-A-1-103604) or production of various ester and ether derivatives by reaction of hydroxyl groups of vinylphenol polymers And methods for producing various nucleus-substituted derivatives of vinylphenol-based polymers are also known. In the production of these vinylphenol-based polymers, generally, starting materials or auxiliary materials include metals such as sodium, iron and calcium. In addition, it is extremely difficult to avoid mixing of metal from the material of the manufacturing apparatus or contamination of the manufacturing apparatus or the environment during the manufacturing operation. Therefore, the presence of metallic impurities such as sodium, iron and calcium in the vinylphenol-based polymers produced by these methods is inevitable.

On the other hand, a vinylphenol polymer is a very useful substance as a material for photoresists, IC encapsulants, printed wiring boards and the like, and has many applications in these electronics fields. By the way, in these devices in the electronics field, in recent years, it has become necessary to make the content of metal impurities in the materials used for achieving higher precision and exhibiting high-performance electrical characteristics to be extremely small. Therefore, in order to use the vinylphenol-based polymer as a material for the electronics field, the metal impurities are removed from the product produced by the above method,
It was necessary to reduce the content to a very small amount.

Therefore, as a conventional method for removing metal impurities from a vinylphenol polymer, (a) a metal removal method in which a vinylphenol polymer is dissolved in a solvent and brought into contact with a strongly acidic cation exchange resin in a solution state (JP-A-5-148308), (B) Far-ultraviolet transmission through which a vinylphenol polymer is dissolved in a solvent and subjected to a specific hydrogenation step in a solution state and a metal removal step of contacting with a strongly acidic cation exchange resin. Method for obtaining a vinylphenol polymer having a high rate and a reduced metal content (JP-A-5-1
No. 48309), and (c) a vinylphenol polymer are dissolved in a solvent and brought into contact with an aqueous solution containing an acidic compound in a solution state, and then further contacted with ion-exchanged water (JP-A-6-192318). ) Is proposed.

However, in the method of contacting with a strongly acidic cation exchange resin such as the above (a) or (b), the passage speed of the solution of the vinylphenol polymer is too high in order to increase the degree of metal removal. That the productivity is not good because it can not be, depending on the type of solvent, the solvent partially decomposes to produce an acid, vinylphenol-based polymer obtained by mixing it is not preferable as a photoresist material. There is a problem that a large amount of washing water and a solvent are required for so-called conditioning for bringing a commercially available strong acid cation exchange resin into a state suitable for metal removal. In addition, in the method of contacting with an aqueous solution containing an acidic compound as described in (c) above, the vinylphenol polymer solution and the aqueous solution may form an emulsion and separation may be difficult. There is a problem in that it may occur, and vacuum distillation is required to remove water from the solution after washing with water, which complicates the process.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the conventional metal removal method for vinylphenol polymers and to efficiently and economically use vinylphenol with a simple device and operation. It is an object of the present invention to provide a method capable of removing metal impurities from a polymer and reducing the content thereof to a very small amount.

[0007]

Means for Solving the Problems As a result of research to achieve the above object, the present inventors have found that a vinylphenol polymer is dissolved in a solvent and passed through a filter which produces a zeta potential by a cationic charge control agent. The present invention has been completed by finding that the above object can be easily achieved by the above.

Therefore, the gist of the present invention is to dissolve a vinylphenol polymer in a solvent and pass it in a solution state through a filter which produces a zeta potential by a cationic charge control agent. Exists in metal removal method.

Examples of vinylphenol polymers to which the method of the present invention is applied include the following. (a) A homopolymer of vinylphenols such as p-vinylphenol or m-vinylphenol. If necessary, isomers such as p-form or m-form may be mixed. (b) a copolymer of vinylphenols and other comonomers such as styrene, acrylic acid or its esters, methacrylic acid or its esters, maleic anhydride, maleic acid or its esters, and further maleimides. And the proportion of comonomer is 70 mol% or less, preferably 50 mol% or less. (c) Esters such as acetic acid and benzoic acid of the phenolic hydroxyl group of the polymer of (a) or (b) above, or ethers such as methyl ether, tert-butyl ether and trimethylsilyl ether of the phenolic hydroxyl group of the polymer . (d) Nuclear substitution products such as alkylated products, halogenated products and methylolated products of the aromatic nucleus of the polymer of (a) or (b) above. (e) A heat-melted modified product of the polymer of (a) or (b) above alone or with a novolac type phenol resin. (f) A hydrotreated reformer of the polymer of (a) or (b) above.

In the method of the present invention, the various vinylphenol polymers as described above are dissolved in a solvent and passed through a filter which produces a zeta potential by a cationic charge control agent in a solution state. The solvent that dissolves the vinylphenol polymer may be any solvent that can dissolve the vinylphenol polymer. For example, alcohols such as methanol, ethanol, and isopropanol; esters such as ethyl acetate and ethyl lactate; cyclics such as tetrahydrofuran and dioxane depend on the type of vinylphenol polymer and the treatment conditions. Ethers; ketones such as acetone and methyl ethyl ketone; alkylene glycol ethers and esters such as ethylene glycol ethyl ether, ethylene glycol ethyl ether acetate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether and propylene glycol monomethyl ether acetate.

The filter which produces a zeta potential by the cationic charge control agent used in the method of the present invention is a filter which is given a cationic charge by the cationic charge control agent and produces a zeta potential with the charged substance in the liquid passing therethrough. (Hereinafter referred to as "filter generating zeta potential"). A filter that produces a zeta potential is generally manufactured by adding a cationic charge control agent to a filter medium. The filtering agent is generally composed of a particle component and a fiber component, and the particle component is generally diatomaceous earth, perlite, activated carbon, zeolite or the like, and the fiber component is cotton, pulp, cellulose acetate or polyester fiber. Etc. are generally used. As the cationic charge control agent, polyamide-amine epichlorohydrin cation resin as described in JP-B-63-17486 and N, N'- as described in JP-B-36-20045. Resins reacted with diethanolpiperazine, melamine, formalin and glycerin phthalate, melamine-formaldehyde cation resins as described in U.S. Pat. No. 4,007,113, dicyandiamide, mono as described in U.S. Pat. No. 2,802,820. Reactants of ethanolamine and formaldehyde, aminotriazine resins such as those described in U.S. Pat. No. 2,839,506 are commonly used, among which polyamide-amine epichlorohydrin cation resins filter stable cationic charges. Given, it is preferably used. The filtration accuracy of the filter is not particularly limited, but about 0.1 to 1.0 μm is suitable. In the method of the present invention, any commercially available filter can be used as long as it produces a zeta potential. For example, Zeta Plus manufactured by Cuno Co., Ltd. is preferably used.

In passing the solution of the vinylphenol polymer through the filter which produces a zeta potential, the filter is previously washed with pure water or a solvent such as methanol or acetone in order to prevent the eluate from mixing with the filter. Is desirable. The concentration of the vinylphenol polymer in the vinylphenol polymer solution when passing through the filter is not particularly limited, but if it is too high, the viscosity of the solution becomes high and it is high to pass through the filter. It is not preferable because it requires pressure. On the other hand, if the concentration is too low, there is an advantage that it can be operated at a low pressure, but the treatment amount of the vinylphenol polymer is reduced, which is not preferable. A concentration in the range of 10 to 40% by weight is usually suitable. A higher rate of passage through the filter is preferable from the viewpoint of productivity, but if the flow rate is too high, a high pressure is required to pass through the filter, and the metal adsorption efficiency due to the zeta potential decreases. Usually, the range of 0.1 to 10 l / m ² · min is suitable.

The temperature at which the vinylphenol polymer solution is passed through the filter is usually room temperature, but raising the temperature has the advantage that the viscosity of the solution decreases and the passing speed increases and the adsorption speed increases. However, if the temperature is too high, the filter may be deteriorated, the solvent may be decomposed, and the vinylphenol polymer may be deteriorated. Generally, the range of room temperature to 50 ° C is suitable.

When the vinylphenol polymer solution is passed through a filter which produces a zeta potential according to the method of the present invention, pretreatment is carried out in advance with an ordinary filter which does not produce a zeta potential. Therefore, the increase in the pressure required for passing the vinylphenol polymer solution through the filter due to the clogging of the filter that causes the zeta potential is reduced, and at the same time, the deterioration of the adsorption and collection ability of the metal due to the zeta potential is suppressed, and The life of the filter that causes As a normal filter for this pretreatment, either a filter surface filtration type or a filter medium filtration type may be used,
Further, it is suitable that the material thereof is, for example, cellulose, cotton, polypropylene, polytetrafluoroethylene, or the like, and one that does not elute impurities such as metal. Further, the filtering accuracy of a normal filter for this pretreatment is appropriately about 0.1 to 1.0 μm, which is the same level as that of a filter generating a zeta potential, but is not particularly limited thereto.

Further, when the method of the present invention is applied to the hydrogen-treated reformed product (f) among the various vinylphenol polymers, a photoresist for producing a next-generation highly integrated semiconductor memory. A vinylphenol polymer suitable as a material is obtained. That is, a photoresist material for manufacturing a next-generation highly integrated semiconductor memory is required to have a high transmittance for far-ultraviolet light, particularly KrF excimer laser light having a wavelength of 248 nm, and a low impurity metal content. However, the hydrogen treatment reformer is
Since the transmittance of KrF excimer laser light having a wavelength of 8 nm is high, if the metal is removed by applying the method of the present invention to this, the resulting vinylphenol polymer has a far ultraviolet light transmittance. It is excellent and has a reduced metal content, and is suitable as a photoresist material for manufacturing a next-generation highly integrated semiconductor memory. Further, the hydrogen-treated reformed product is generally prepared by dissolving a vinylphenol polymer in a solvent to form a solution, as described in JP-A-1-103604.
It can be obtained by performing hydrogen treatment in the presence of a Group II metal catalyst, and the inventors of the present invention have found the following regarding the method of applying the method of the present invention thereto. That is, after the vinylphenol-based polymer is subjected to hydrogen treatment, the hydrogen-treated liquid is used as it is or without isolation, without isolating the hydrogen-treated reformed product of the vinylphenol-based polymer from the hydrogen-treated liquid. After adjusting the concentration of the hydrogen treatment reformer,
It has been found that a polymer having excellent transparency to far-ultraviolet light and reduced impure metal can be obtained easily, efficiently and economically by passing it through a filter generating a zeta potential. It is needless to say that the hydrotreating solution may be pretreated with an ordinary filter that does not generate a zeta potential, if necessary, before passing through the filter that generates a zeta potential.

The method of applying the method of the present invention to the above-mentioned hydrogen treatment liquid for vinylphenol polymers will be described in more detail. First, as described above, the hydrogen treatment for vinylphenol polymers is generally carried out according to Japanese Patent Laid-Open No. No. 103604, a vinylphenol polymer is dissolved in a solvent to form a solution, and the solution is brought into contact with hydrogen in the presence of a Group VIII metal catalyst. The solvent for this hydrogen treatment is capable of dissolving the vinylphenol polymer and is stable during the hydrogen treatment of the vinylphenol polymer, and is also common to the metal removal treatment in the filter that produces the zeta potential of the present invention. A solvent that can be used is used. Examples thereof include the same various solvents as the examples of the solvent that can be used in the metal removal treatment with the filter that generates the zeta potential. The amount of these solvents used in the hydrogen treatment is usually within the range where the concentration of the polymer in the solution is 10 to 50% by weight.
There is no particular need to limit this range. Suitable Group VIII metal catalysts are nickel, cobalt, palladium, platinum and rhodium. The form thereof may be either a simple metal or a metal oxide carrier supported. Nickel and cobalt are also used as the so-called Raney type.
The contact between the p-vinylphenol polymer solution and hydrogen in the presence of these metal catalysts is carried out by appropriately selecting either a batch system using an autoclave or a continuous system such as a fixed bed flow system. The temperature of the hydrotreatment is suitably 50 to 300 ° C, preferably 150 to 250 ° C. The hydrogen pressure is appropriately 10 to 200 kg / cm ² , and preferably 50 to 100 kg / cm ² . In the case of a batch system, the amount of the catalyst used is 0.01 as a metal based on the polymer.
It is suitable that the flow rate of the polymer with respect to the catalyst is about 0.1 to 10 kg / kg · hr in the case of the flow type. The treatment time may be arbitrarily selected according to the type of catalyst used, the amount thereof, the treatment conditions such as the treatment temperature, the characteristics of the polymer to be treated, and the like.

The hydrogen treatment liquid obtained by the above hydrogen treatment is
Next, if the catalyst is contained, the catalyst is removed, and then the metal is subjected to a metal removal treatment with a filter that produces a zeta potential according to the present invention. At this time, the hydrogen treatment liquid may be subjected to the metal removal treatment as it is, or if necessary, a solvent may be added to the hydrogen treatment liquid, or a part of the solvent may be removed from the hydrogen treatment liquid by evaporation, The metal concentration may be adjusted before the polymer is subjected to the metal removal treatment. As the solvent to be added to the hydrotreatment liquid, the same solvent as that used in the hydrotreatment is suitable. However, when two kinds of mixed solvents are used in the hydrogenation process, only one solvent is used. Does not matter.

The vinylphenol polymer from which the metal has been removed by the method of the present invention as described above may be used in various applications while adjusting the amount of the solvent in the solution state, or the solution may be used as a pure solution. A purified product may be prepared by a method of pouring in water to precipitate the polymer, followed by filtration and drying, or a method of heating the solution under reduced pressure to remove the solvent and drying.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to these examples. Further, in the following Examples and Comparative Examples, ratios and percentages are by weight unless otherwise specified.

Example 1 Poly p-vinylphenol (weight average molecular weight 5000)
Was dissolved in propylene glycol monomethyl ether acetate to give a 25% solution. Zeta Plus 90LA (90 mm diameter, 3 mm thickness, filtration accuracy of about 0.1 μm) manufactured by Kuno Co., Ltd., which is a filter that generates a zeta potential; composed of a filter material of perlite / diatomaceous earth / cellulose and a cationic charge control resin 200 ml of pure water, 200 ml of methanol and 200 ml of propylene glycol monomethyl ether acetate.
After being successively washed with, the solution of poly-p-vinylphenol was passed through at a rate of 19 g / min. If this passing speed is converted into SV for the filter, the SV will be 60 g / ml · hr. When the metal content in the solution was measured by a flameless atomic absorption spectrometer, the amount of metal in the solution before treatment was 262 ppb for sodium and 63 pp for iron.
b, calcium was 34 ppb, and the amount of metal in the solution after the treatment was 4 ppb or less for sodium, 4 ppb for iron, and 5 ppb for calcium. Further, when the amount of acid in the solution was potentiometrically titrated with 0.02 N potassium hydroxide,
The solution before treatment was 0.001 meq / g and the solution after treatment was 0.002 meq / g. The acid amounts of the solution before and after the treatment were almost the same, and the decomposition of the solvent used was not substantially observed. .

Comparative Example 1 Poly-p-vinylphenol (weight average molecular weight 5000)
Was dissolved in propylene glycol monomethyl ether acetate to give a 25% solution. Diaion RCP-160H manufactured by Mitsubishi Kasei Co., Ltd., which is a strongly acidic cation exchange resin.
(Sulfonate of styrene / divinylbenzene cross-linked polymer, high-porous type) 60 ml was filled in a glass tube having an inner diameter of 20 mm, treated with 3% hydrochloric acid 1 l, and subsequently purified water 1
l, 500 ml of methanol and 500 ml of propylene glycol monomethyl ether acetate were successively washed.
The solution of poly-p-vinylphenol was passed through this column at a rate of 1.5 g / min. If this passing speed is converted into SV for a strongly acidic cation exchange resin, S
V is 1.5 g / ml · hr. The amount of metal in the solution before the treatment was as shown in Example 1, and the amount of metal in the solution after the treatment was 4 ppb or less for sodium, 3 ppb for iron,
Calcium was 4 ppb. The amount of acid in the solution after the treatment was 0.025 meq / g. The amount of acid in the solution after the treatment was an order of magnitude larger than 0.002 meq / g of the amount of acid in the solution after the treatment in Example 1, and the decomposition of the solvent used during the treatment substantially occurred. It is recognized that

Example 2 Poly-p-vinylphenol (weight average molecular weight 6000)
750 g was dissolved in 2025 g of isopropanol and 225 g of methanol to give a 25% solution. This solution was heated at a temperature of 200 with an autoclave using nickel as a catalyst.
Hydrogen treatment was carried out at a temperature of 70 ° C and a pressure of 70 kg / cm ² for 3 hours.
The treated solution was passed through a 1 μm filter to separate the nickel catalyst by filtration. Then, it was passed through the same Zeta Plus 90LA manufactured by Kuno Co., Ltd. as in Example 1 at a speed of 10 g / min. The amount of metal in poly-p-vinylphenol before hydrogen treatment is 1160 ppb for sodium and 210 pp for iron.
b, calcium is 124 ppb, 1.0 × 10 ⁻⁴
The light transmittance of the ethanol solution having a concentration of g / ml at 248 nm was 59.1%. After hydrogen treatment and filtration of the catalyst, the solvent was removed from the solution by heating under reduced pressure. The dry resin had 950 ppb for sodium and 150 p for iron.
The pb and calcium were 105 ppb, and the light transmittance at 248 nm was 78.5%. After passing the solution obtained by filtering off the catalyst through Zuno Plus 90LA manufactured by Kuno Co., the amount of metal in the dried resin after removing the solvent by heating under reduced pressure was 4 ppb or less for sodium, 12 ppb for iron, and 26 ppb for calcium, The light transmittance at 248 nm was 78.3%.

Example 3 Poly-m-vinylphenol (weight average molecular weight 8500)
Was dissolved in isopropyl alcohol to give a 25% solution. The amount of metal in this solution was 92 ppb for sodium, 120 ppb for iron, and 25 ppb for calcium. This solution was passed through Zeta Plus 60LA (same as Zeta Plus 90LA used in Example 1 except that the filtration accuracy was about 0.5 μm) manufactured by Kuno Co., Ltd. at a rate of 12 g / min. After 30 minutes from the start of the filtration, the filtration pressure was 0.
Was 8 kg / cm ^2, amount of metal in the filtrate sodium 3 ppb, iron 6 ppb, calcium was 7 ppb. After 13 hours from the start of the filtration, the filtration pressure is 2.5 kg /
cm ² and the amount of metal in the filtrate is 5 pp sodium
b, iron was 7 ppb, and calcium was 10 ppb.

Example 4 A solution of poly (m-vinylphenol) similar to that in Example 3 was added,
Pretreatment filtration was performed with a 0.1 μm filter made of polytetrafluoroethylene in advance, and then 12 g / min was applied to Zeta Plus 60LA manufactured by Cuno Co., Ltd. as in Example 3.
Was passed at the speed of. The filtration pressure after 30 minutes from the start of passing was 0.8 kg / cm ² , and the amount of metal in the filtrate was 3 ppb for sodium, 5 ppb for iron, and 8 ppb for calcium.
Met. The filtration pressure after 13 hours for the first time is 1.2k
g / cm ² , and the amount of metal in the filtrate was 4 for sodium.
ppb, iron was 5 ppb, and calcium was 10 ppb. In this example, since the pretreatment filtration was performed with the filter made of polytetrafluoroethylene in advance, the filtration pressure after 13 hours was about half that in the case of Example 3.

Example 5 p-Vinylphenol / methylmethacrylate (55: 4)
The copolymer (weight average molecular weight 8100) (5 mol ratio) was dissolved in ethyl lactate to prepare a 25% solution. This solution was added to Zeta Plus 90LA manufactured by Kuno Co., Ltd. in the same manner as in Example 1.
It was passed through at a speed of 0 g / min. The amount of metal in the solution before passing was 135 ppb for sodium, 90 ppb for iron, and 65 ppb for calcium. The amount of metal in the filtrate was 3 ppb for sodium, 20 ppb for iron, and 5 pp for calcium.
It was pb.

Example 6 Brominated poly-p-vinylphenol (bromine substitution degree 1.5 /
The core and the weight average molecular weight of 6500) were dissolved in diethylene glycol dimethyl ether to prepare a 25% solution. This solution is the same as in Example 1 manufactured by Cuno Co., Ltd. Zeta Plus 90.
It was passed through the LA at a rate of 10 g / min. The amount of metal in the solution before passing was 87 ppb for sodium and 96 pp for iron.
b, calcium was 65 ppb, and the amount of metal in the filtrate was 5 ppb for sodium, 3 ppb for iron, and 5 ppb for calcium.

[0027]

According to the method of the present invention, a wide range of metal impurities such as alkali metals such as sodium, iron and calcium, alkaline earth metals, transition metals, etc. from various vinylphenol polymers can be obtained at a zeta potential in a solution form. It can be removed efficiently and economically by the simple operation and equipment of passing it through the resulting filter. In addition, the vinylphenol-based polymer from which metal impurities have been removed by the method of the present invention has a significantly reduced content of metal impurities and can be suitably used as a material in the field of electronics. In particular, when the method of the present invention is applied to a hydrogen treatment liquid obtained by hydrogenating a vinylphenol polymer in a solution form, it is easily and efficiently and economically excellent in far-ultraviolet light transmission and has a metal impurity content. A highly preferred reduced photoresist material is obtained.

Claims (3)

[Claims] 1. A method for removing a metal from a vinylphenol polymer, which comprises dissolving the vinylphenol polymer in a solvent and allowing the solution to pass through a filter that produces a zeta potential by a cationic charge control agent. 2. The vinylphenol according to claim 1, wherein a solution in which a vinylphenol polymer is dissolved in a solvent is passed through a filter which does not generate a zeta potential in advance, before being passed through a filter which generates a zeta potential by the cationic charge control agent. Method for removing metal from polymer. 3. A solution obtained by dissolving a vinylphenol polymer in a solvent, which is passed through a filter which produces a zeta potential by a charge control agent, and which is a solution of the vinylphenol polymer in the solvent. The method for removing a metal from a vinylphenol-based polymer according to claim 1 or 2, which is a hydrogen treatment liquid which has been brought into contact with hydrogen in the presence of.