JP2008037966A - Partially neutralized poly(meth)acrylic acid product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a partially neutralized poly(meth)acrylic acid product excellent in solubility and dispersibility into water. <P>SOLUTION: This manufacturing method for the partially neutralized poly(meth)acrylic acid product is performed through photopolymerization of a monomer mixture containing (meth)acrylic acid and its salt by irradiating an aqueous solution of the monomer mixture with a light containing a UV ray under the presence of a photoinitiator, in which the light is irradiated through an optically transparent material, the UV ray (330-370 nm wavelength) transmittance of which is ≥80%, arranged between a light source and the aqueous solution of the monomer mixture. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a partially neutralized poly (meth) acrylic acid, and relates to a method for producing a partially neutralized poly (meth) acrylic acid having properties excellent in water solubility and dispersibility.

  The poly (meth) acrylic acid partially neutralized product is useful as a dispersant for various pigments, a scale inhibitor, a cleaning builder, a thickener, a binder, and a base for a medical poultice or a haptic agent. Widely used in various fields.

  In general, a partially neutralized poly (meth) acrylic acid is obtained by adding an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate, or a monomer containing (meth) acrylic acid to water. It is produced by radical polymerization of a mixed aqueous solution in which a compound that neutralizes an acid such as sodium oxide or potassium hydroxide is mixed.

  For example, Patent Document 1 discloses that a monomer having (meth) acrylic acid (salt) as a main component is photopolymerized in an aqueous medium and has a weight average molecular weight of 600,000 or more and a dispersity of 5 A (meth) acrylic acid (salt) -based polymer of ˜60 is described. Patent Document 1 describes that a monomer mainly composed of (meth) acrylic acid (salt) is photopolymerized using near ultraviolet rays having a wavelength region of 300 nm or more and 500 nm or less.

  Further, in Example 3 of Patent Document 2, an aqueous solution containing acrylic acid and sodium acrylate is continuously supplied onto a movable resin belt and photopolymerized to obtain a hydrous polymer, which is peeled off. A method for producing a hydrous polymer is described. In paragraphs 0039 and 0040, the vinyl monomer aqueous solution is photopolymerized in an airtight chamber supplied with an inert gas to prevent polymerization inhibition by oxygen, and an upper surface of the airtight chamber is exposed from a light source. It describes that it has a light-transmitting material that can transmit light.

  However, the conventional poly (meth) acrylic acid partial neutralized product described in the above-mentioned patent document is extremely increased in viscosity immediately after being charged into an aqueous solution, and stirring becomes difficult. Thereafter, the viscosity gradually decreases as stirring is continued. As described above, since the variation in viscosity with time is remarkable, there is a difficulty in handling.

  Specifically, for example, in the preparation of a poultice, there is a step of mixing polyacrylic acid partially neutralized product, glycerin, water, etc., but since the viscosity increases in the initial stage of stirring in that step, the motor load of the stirrer And the stable production was difficult. Conversely, when mixed with a stirrer having a high kneading capacity, the polyacrylic acid partial neutralized product is mechanically cut, and the viscosity of the mixed dispersion decreases as the stirring time elapses. There was also a problem that a viscose patch could not be obtained. Therefore, in order to produce a poultice having a stable quality, a great effort has been required to optimize the stirring force.

  Such problems occur because the conventional poly (meth) acrylic acid partially neutralized product has insufficient solubility and dispersibility in water or a mixed solvent of water and a polyhydric alcohol such as glycerin. It was thought that there was.

  Conventionally, the viscosity of a 0.2% aqueous solution of partially neutralized polyacrylic acid has been used as an index measurement value.

  However, in practice, the so-called “mako” is produced by adding the powder polymer (polyacrylic acid partially neutralized product) to the water at the time of adjusting the aqueous solution. Although the stirring intensity and the stirring mode are changed, the “mamako” does not disperse and swells in the “mako” state, and remains in a 0.2% aqueous solution as a high concentration polymer aggregate.

  As described above, a concentration distribution is locally generated even in the case of a 0.2% aqueous solution, and immediately after adjustment of the viscosity of the 0.2% aqueous solution, a measured value of high viscosity is often exhibited. Therefore, the measurement accuracy of the viscosity was low, the reproducibility in repeated measurement was low, and the measurement value itself was unstable.

  By adjusting the viscosity of 0.2% aqueous solution to improve the accuracy of measurement values and reproducibility in repeated measurements, for example, by standing for 24 hours and leaving it in a constant temperature bath at 20 ° C., by mechanical stirring A comparatively stable viscosity measurement value was obtained by measuring the viscosity after swelling the polymer as much as possible while suppressing the cutting of the polymer as much as possible.

  However, the adjustment / mixing of the powder polymer and the dispersion medium such as water in an actual polymer user, such as a poultry material manufacturer, is estimated to be much shorter than 24 hours (for example, about 30 minutes), The actual situation is that there is a large gap between the quality control based on the viscosity measurement value after standing for a long time at the powder polymer manufacturer and the actual usage at the poultice manufacturer, and it is not possible to meet customer requirements.

  Furthermore, the “residual residue” obtained by filtering a high-concentration polymer aggregate swollen in an aqueous solution for measuring viscosity with a sieve or glass filter is quantitatively measured. This indicator has traditionally been used. However, this index also has low measurement accuracy and measurement reproducibility, and only a rough judgment can be made as an index.

  If there is a lot of “insoluble matter”, it may cause uneven or insufficient “cross-linking” reaction in the manufacturing process of the poultice preparation manufacturer, causing unstable production of the poultice preparation manufacturer, unstable quality of the poultice preparation. Cause inconvenience.

  The “crosslinking” reaction in the manufacturing process of the poultice manufacturer is a reaction performed between the crosslinking agent and the polyacrylic acid partial neutralized polymer in the adjustment liquid. Therefore, it is necessary that the polyacrylic acid partially neutralized product is quickly and uniformly dispersed in the adjustment liquid. The more insoluble matter, the lower the ratio of effective “crosslinking” reaction. Problems occur in manufacturing process management and quality control.

  “The amount of insoluble matter is low or zero” of the partially neutralized polyacrylic acid, and “the viscosity of the adjustment liquid immediately after adding the powdered polyacrylic acid partially neutralized product to a dispersion medium such as water is increased. It is no exaggeration to say that “there is little and no change in viscosity with time” is the point of manufacturing process control, quality improvement, quality stability, and reduction of defective rate at a poultice manufacturer. However, a partially neutralized polyacrylic acid as required by a manufacturer of poultices has not been obtained industrially.

Therefore, there is little “insoluble matter”, or zero, and the increase in the viscosity of the adjustment liquid immediately after charging the powder polymer into the dispersion medium such as water is suppressed. A partially neutralized polyacrylic acid that is uniformly dispersed therein has been desired. The reason why the partially neutralized polyacrylic acid is uniformly dispersed in the dispersion medium promptly is that the production state of the poultice is stabilized and finally contributes to the stability of the quality of the poultice.
JP 2004-10831 A JP 2002-3509 A

  As mentioned above, the conventional poly (meth) acrylic acid partially neutralized product has a large variation in viscosity over time when it is made into an aqueous solution, and there is an insoluble matter in water, so it is soluble in water. And dispersibility was not sufficient. Then, an object of this invention is to provide the poly (meth) acrylic acid partial neutralized material excellent in the solubility with respect to water, and a dispersibility, and its manufacturing method.

  As a result of intensive studies in order to solve the above problems, the present inventor has obtained a light-transmitting material made of borosilicate glass in an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate. It was found that a partially neutralized poly (meth) acrylic acid having excellent solubility and dispersibility in water can be produced by irradiating with light from an external light source and photopolymerizing. Results of further research based on this finding. The present invention has been completed.

  That is, this invention provides the following poly (meth) acrylic acid partial neutralized material and its manufacturing method.

  Item 1. In the presence of a photopolymerization initiator, an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate is irradiated with light containing ultraviolet rays to photopolymerize the monomer mixture to produce poly ( A method for producing a partially neutralized (meth) acrylic acid, wherein a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm is provided between a light source and an aqueous solution of the monomer mixture. A method for producing a partially neutralized poly (meth) acrylic acid, which comprises irradiating with light.

  Item 2. Item 2. The method according to Item 1, wherein the aqueous solution of the monomer mixture is irradiated with light in an inert gas atmosphere.

  Item 3. Item 3. The method according to Item 1 or 2, wherein the light transmissive material is borosilicate glass or quartz glass.

  Item 4. Item 4. The production method according to Item 1, 2, or 3, wherein the monomer mixture is continuously photopolymerized on a movable belt.

  Item 5. The light source is at least one selected from the group consisting of light-emitting diodes, fluorescent lamps for insect traps and photochemistry, fluorescent blue lamps, metal halide lamps, high-pressure mercury lamps, black light fluorescent lamps, black light mercury lamps, and black light bulb-type fluorescent lamps. Item 5. The production method according to any one of Items 1 to 4, which is a seed.

  Item 6. Item 6. The production method according to any one of Items 1 to 5, wherein a light source having a wavelength of irradiation light in a range of 357 to 377 nm is used.

  Item 7. Item 7. A partially neutralized poly (meth) acrylic acid produced by the production method according to any one of Items 1 to 6.

Item 8. A poly (meth) acrylic acid partial neutralized product comprising a monomer containing (meth) acrylic acid and (meth) acrylate as a structural unit and having the following physical properties:
(1) Viscosity at 20 ° C. after stirring a mixed solution of 0.2% by weight of the partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerol and 93.1% by weight of water for 15 seconds (A) Is in the range of 200 to 800 mPa · s,
(2) Viscosity at 20 ° C. after stirring a mixed solution of 0.2% by weight of the partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerin and 93.1% by weight of water at 20 ° C. (B) Is in the range of 200 to 800 mPa · s, and (3) the ratio of the viscosity B to the viscosity A (B / A) is in the range of 0.8 to 1.2.

  Item 9. An apparatus for producing a partially neutralized poly (meth) acrylic acid, a reaction vessel containing an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate, and a gas containing the reaction vessel A light source that irradiates light including ultraviolet light outside the hermetic chamber and above the hermetic chamber is formed, and the upper surface of the hermetic chamber is formed of a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm. A device characterized by that.

  Item 10. A unit for continuously producing a partially neutralized poly (meth) acrylic acid, and supplying an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate to a movable belt A body mixture supply unit, a movable belt having a liquid reservoir for containing an aqueous solution of the monomer mixture, a hermetic chamber for photopolymerization disposed along the traveling direction of the movable belt, and the airtight chamber A light source for irradiating light including ultraviolet light is provided above the outside, and the upper surface of the hermetic chamber is formed of a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm. apparatus.

  The partially neutralized poly (meth) acrylic acid obtained in the present invention is excellent in solubility and dispersibility, easy to handle in aqueous solution, dispersants such as various pigments, scale inhibitors, cleaning builders, thickening It is useful for an agent, a binder, a base for a medical poultice or a haptic agent, and particularly useful for a base for a pharmaceutical poultice or a haptic agent.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to these examples, and can be appropriately modified as long as the gist of the present invention is not changed.

  In the method for producing a partially neutralized poly (meth) acrylic acid according to the present invention, light is added to an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate in the presence of a photopolymerization initiator. When the monomer mixture is photopolymerized by irradiation, a light transmissive material having an ultraviolet transmittance of 80% or more in the wavelength range of 330 to 370 nm is interposed between the light source and the aqueous solution of the monomer mixture. And irradiating with light. Thereby, the poly (meth) acrylic acid partial neutralized product excellent in the solubility with respect to water and a dispersibility is manufactured.

  Here, (meth) acrylic acid means acrylic acid or methacrylic acid. (Meth) acrylic acid salt means a neutralized product of (meth) acrylic acid, and is a neutralized product obtained by neutralizing (meth) acrylic acid with an alkali metal, ammonia, organic amine or the like. Examples include sodium (meth) acrylate, potassium (meth) acrylate, calcium (meth) acrylate, magnesium (meth) acrylate, and ammonium (meth) acrylate. These may be used alone or in combination of two or more. Good. Among these, sodium (meth) acrylate is preferable. In the present invention, a (meth) acrylic acid salt in which the acid portion has been previously neutralized may be used as a raw material, and after (meth) acrylic acid is polymerized, it is partially formed by sodium hydroxide, potassium hydroxide, or the like. It may be neutralized.

  In the poly (meth) acrylic acid partial neutralized product of the present invention, other monomers can be copolymerized as long as the intended effect of the present invention is not impaired. Examples of such monomers include α-hydroxyacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid and other unsaturated carboxylic acids and their salts, 2-acrylamido-2-methylpropanesulfonic acid, (meta ) Unsaturated sulfonic acids such as allyl sulfonic acid and styrene sulfonic acid, and salts thereof. If necessary, one or more of these may be used in a range of 20 mol% or less based on the total amount of (meth) acrylic acid and (meth) acrylate.

  The proportion of (meth) acrylic acid and (meth) acrylate in the partially neutralized poly (meth) acrylic acid of the present invention is usually about 10/90 to 90/10, preferably 40/60 in molar ratio. It may be about ˜70 / 30, more preferably 45/55 to 65/35. This ratio can be appropriately selected depending on the use of the partially neutralized poly (meth) acrylic acid. When the molar ratio of (meth) acrylic acid to (meth) acrylate exceeds 90/10, the insoluble content in the aqueous solution tends to increase.

  The partially neutralized poly (meth) acrylic acid of the present invention can be obtained by radical polymerization of (meth) acrylic acid, (meth) acrylic acid salt and, if necessary, other monomer mixtures. It is also possible to polymerize a mixture of (meth) acrylic acid and other monomers and an alkali metal hydroxide, ammonia or the like, which is a compound that neutralizes the acid.

  Examples of the polymerization method include known polymerization methods such as aqueous solution polymerization method, slurry polymerization method, suspension polymerization, emulsion polymerization, etc., but from the viewpoint of solvent removal, solvent safety, and surfactant incorporation, aqueous solution polymerization method Is preferred.

  In the aqueous solution polymerization method, an aqueous solution of the monomer is adjusted to a predetermined concentration, and dissolved oxygen in the reaction system is sufficiently replaced with an inert gas, and then a radical polymerization initiator is added, and if necessary, heating or ultraviolet rays are added. It is a method of performing a polymerization reaction by irradiating light. In the present invention, photopolymerization by irradiation with light (such as ultraviolet rays) is preferable because the polymerization reaction is possible even at a low temperature, the reaction progress rate is good, and a low polymer or gel can be reduced.

  As a photopolymerization method in the production of the partially neutralized poly (meth) acrylic acid, a method of irradiating a mixed aqueous solution containing the monomer mixture, a photopolymerization initiator and a chain transfer agent with light such as ultraviolet rays is preferable. Adopted.

  There is no restriction | limiting in particular as a photoinitiator, A well-known photoinitiator is suitably selected according to the objective and used. For example, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis Azo photopolymerization initiators such as (N, N′-dimethyleneisobutylamidine), 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane], 1-benzoyl-1 Examples include ketones such as hydroxycyclohexane and benzophenone, benzoin and alkyl ethers thereof, benzyl ketals, and anthraquinone derivatives, among which azo photopolymerization initiators are preferable.

  It is preferable that the usage-amount of a photoinitiator is 10-10000 ppm with respect to all the monomers, More preferably, it is 10-5000 ppm. When the photopolymerization initiator is less than 10 ppm, polymerization does not occur sufficiently, and when it exceeds 10,000 ppm, the degree of polymerization of the resulting polymer is lowered.

  The chain transfer agent is used for adjusting the molecular weight of the resulting partially neutralized poly (meth) acrylic acid and the viscosity of the aqueous solution, and for reducing the insoluble content.

  Chain transfer agents include mercaptoethanol, mercaptopropionic acid, thioglycols, sulfur-containing compounds such as thioacetic acid, alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, and phosphorous compounds such as phosphorous acid and sodium phosphite. And hypophosphite compounds such as sodium hypophosphite, and these may be used alone or in combination of two or more. Among these chain transfer agents, sulfur-containing compounds are preferable, and 2-mercaptoethanol, 3-mercaptopropionic acid, and thioglycolic acid are more preferable.

  The amount of the chain transfer agent used is preferably 1 to 500 ppm, more preferably 1 to 300 ppm, based on all monomers. If the chain transfer agent is less than 1 ppm, a sufficient effect cannot be obtained, and if it exceeds 500 ppm, the degree of polymerization is lowered, which is not preferable. Since the chain transfer agent affects the aqueous solution insoluble content of the resulting poly (meth) acrylic acid partial neutralized product, it is desirable to adjust the amount of use as appropriate.

The photopolymerization reaction that is a typical polymerization method of the partially neutralized poly (meth) acrylic acid of the present invention will be described. As light to be irradiated upon photopolymerization, ultraviolet rays and / or visible rays are used, and among these, ultraviolet rays are preferably used. The ultraviolet illuminance is determined in consideration of the type of monomer, the type and concentration of the photopolymerization initiator, the viscosity of the target polymer, and the polymerization time, but is generally 0.01 to 1000 mW / cm ² . it is preferred, more preferably from 0.05~100mW / cm ^2, more preferably from 0.1 to 10 MW / cm ^2. The ultraviolet illuminance may be constant during the polymerization reaction or may be changed during the polymerization. The light source is not particularly limited as long as it can emit ultraviolet rays and / or visible light capable of photopolymerizing monomers, and examples thereof include light emitting diodes, fluorescent lamps for trapping and photochemistry, fluorescent blue lamps, and metal halide lamps. A high-pressure mercury lamp, a black light fluorescent lamp, a black light mercury lamp, a black light bulb-type fluorescent lamp, or the like can be used. Among these, it is desirable to use a light emitting diode or a black light fluorescent lamp. The light source may be one type or two or more types.

  In the method for producing a partially neutralized poly (meth) acrylic acid according to the present invention, an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate in the presence of a photoinitiator contains ultraviolet rays. When performing photopolymerization by irradiating light, a light-transmitting material having an ultraviolet transmittance of 80% or more in the wavelength range of 330 to 370 nm is interposed between the light source and the aqueous solution of the monomer mixture. It is characterized by light irradiation. That is, the light from the light source passes through the light transmissive material and reaches the aqueous solution of the monomer mixture. Thereby, it can photopolymerize effectively using the ultraviolet-ray of the wavelength range of 330-370 nm, and can greatly improve the conversion rate from a monomer to a polymer. Moreover, since the illuminance of light increases, a polymer with a narrow molecular weight distribution with little variation in the degree of polymerization can be produced. Therefore, the obtained poly (meth) acrylic acid partially neutralized product is excellent in solubility and dispersibility when it is made into an aqueous solution, the viscosity change with time is greatly reduced, and the insoluble matter is greatly reduced.

  Examples of light transmissive materials include quartz glass, borosilicate glass, soda lime glass, polymethyl methacrylate, polycarbonate, and polyvinyl chloride that are recognized as transparent by human eyes. In this case, it is necessary to select quartz glass or borosilicate glass, which is a light-transmitting material having a high ultraviolet light transmittance in the wavelength range of 330 to 370 nm.

  The reason for this is that the wavelength that efficiently contributes to radical generation by light of the azo initiator is estimated to be 330 to 370 nm. Therefore, a light transmissive material that sufficiently transmits ultraviolet rays in the wavelength range is selected. It is essential.

  If a light-transmitting material having a high ultraviolet transmittance in the wavelength range of 330 to 370 nm is not selected, the polymerization time is delayed and the polymerization conversion rate is lowered, so that the residual monomer concentration increases, and the drying step is a subsequent step of the polymerization step. In this case, the polymer is heated in a state where the residual monomer concentration is high, so that a branched polymer, a crosslinked polymer or a giant polymer is generated as a side reaction. Therefore, as a result, the molecular weight distribution becomes broad, the insoluble content increases, and when the powdered polymer is put into a dispersion medium such as water, the viscosity increase of the adjustment liquid immediately after is greatly increased. That is, a partially neutralized polyacrylic acid that does not uniformly disperse in the dispersion medium immediately, which has a large change in viscosity of the adjustment liquid over time, is produced, and a problem has occurred.

  Moreover, it is difficult to secure an airtight chamber in which the polymerization atmosphere is filled with an inert gas because it is difficult to irradiate the monomer aqueous solution containing initiators directly without passing through a light transmissive material. Is difficult. In addition, it is necessary to take measures to expose the monomer vapor of the ultraviolet ray generator.

  The photopolymerization reaction is performed in an inert gas atmosphere such as nitrogen or carbon dioxide in order to prevent polymerization inhibition due to the presence of oxygen. Of these, a nitrogen atmosphere is preferred. The photopolymerization reaction is usually performed in an airtight chamber filled or supplied with this inert gas.

As described above, examples of the light-transmitting material include borosilicate glass and quartz glass. Particularly, boric acid (B ₂ O ₃ ) is 5 to 20% (particularly 10 to 16%), and SiO ₂ is 65 to 90. % (Particularly 70 to 85%) of borosilicate glass is preferred. The transmittance is a value measured using a spectral irradiance meter (for example, USR-40V manufactured by USHIO INC.).

  This light transmissive material is provided on the upper surface of the hermetic chamber, and allows light from a light source installed outside the hermetic chamber to pass through and irradiate the monomer mixture inside. The shape of the light transmissive material is not particularly limited and may be generally a flat plate shape, and the thickness thereof is not particularly limited, but may be about 0.7 mm to 21 mm from the viewpoint of light transmittance, strength, etc. Is 2.75 to 11 mm.

  Furthermore, at the time of a polymerization reaction, it is preferable to hold | maintain a reaction liquid at 5-95 degreeC, More preferably, it is 5-30 degreeC, More preferably, it is 5-15 degreeC. Cooling may be required to maintain the temperature, and this cooling method is not particularly limited. Usually, the outer periphery of the reaction vessel is cooled with a refrigerant (for example, cold water, cold methanol, etc.) or the like. The photopolymerization reaction of the aqueous solution of the monomer mixture may be either batch type or continuous type. When the photopolymerization reaction is carried out batchwise, the light irradiation time (polymerization time) is preferably 1 to 240 minutes, more preferably 5 to 120 minutes, and further preferably 15 to 60 minutes.

  For example, as a batch type, a reaction vessel that contains an aqueous solution of a monomer mixture, an airtight chamber that contains the reaction vessel, and an apparatus that includes a light source outside the airtight chamber, and an airtight chamber that receives light from the light source A device can be used in which the upper surface is made of a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm.

  Various methods are employed as the continuous polymerization method. For example, an apparatus for producing a partially neutralized poly (meth) acrylic acid by continuously photopolymerizing a monomer mixture on a movable belt. A monomer mixture supply unit for supplying an aqueous solution of the monomer mixture to the movable belt, a movable belt having a liquid reservoir along the longitudinal direction for containing the supplied aqueous solution of the monomer mixture, movable An airtight chamber for performing photopolymerization disposed along the traveling direction of the belt, and a light source for irradiating light including ultraviolet light on the outside of the airtight chamber, the upper surface of the airtight chamber receiving light from the light source having a wavelength of 330 An apparatus formed of a light transmissive material having an ultraviolet transmittance of 80% or more in a range of ˜370 nm can be used.

  Among these, it is preferable to employ a continuous polymerization method because of excellent productivity.

  The operation of the apparatus of the continuous polymerization method is specifically as follows. From one of the movable belts, a monomer mixture aqueous solution is continuously supplied so as to maintain a target depth. In this case, in order to prevent polymerization inhibition of the monomer mixture by oxygen, it is preferable to continuously supply an inert gas such as nitrogen into the hermetic chamber. The belt continuously moves together with the monomer mixture aqueous solution, and the monomer mixture aqueous solution is supplied under a fixed light source. The monomer mixture aqueous solution is polymerized by light irradiated from the light source through the light transmissive material.

  An example of an apparatus for producing a partially neutralized poly (meth) acrylic acid by a continuous polymerization method is shown in FIGS. 1 and 2, and will be described in more detail.

  In FIG. 1, reference numeral 1 denotes a continuously movable resin belt which is stretched between rollers 2 and 3 and rotates in the direction of arrow Q. The resin belt 1 is made of a flexible resin. Specifically, a belt base knitted with fibers such as polyester is laminated or coated with a 4/6 fluororesin, a silicone resin, a polyolefin resin, or the like.

  The resin belt 1 has a liquid reservoir portion 100 along the longitudinal direction at the center side, and the liquid reservoir portion 100 can be used in various shapes as long as the cross section in the width direction has a concave shape. A cross section in the width direction as shown in FIG. 2 is preferable. The height H of the liquid reservoir 100 is preferably a liquid depth of +20 mm, and more preferably 70 to 220 mm. A guide plate (not shown) may be provided along the longitudinal direction of the resin belt so as to ensure that the cross section in the width direction of the resin belt is kept concave, thereby supporting the edge of the resin belt.

  In FIG. 1, reference numeral 4 denotes an airtight chamber having a square cross section disposed along the traveling direction of the resin belt 1, and the belt 1 passes through the airtight chamber 4. The upper surface 5 of the hermetic chamber 4 is formed of a light transmissive material having an ultraviolet transmittance of 80% or more in the wavelength range of 330 to 370 nm, and a plurality of light sources 7 a and 7 b provided above the hermetic chamber 4. The light irradiated from can be transmitted.

  The airtight chamber 4 is supplied with an inert gas such as nitrogen in order to prevent polymerization inhibition by oxygen and to eliminate water vapor generated during the polymerization. 1 and 2 show an example in which an inert gas is supplied to the hermetic chamber.

  A gas supply unit 8 is formed on one side surface of the hermetic chamber 4, and an inert gas such as nitrogen gas passes through a gas line (not shown) to supply a gas formed on one side surface of the hermetic chamber 4. After being supplied into the airtight chamber 4 from the portion 8 and filling the inside of the airtight chamber 4 with an inert gas, the discharge port provided on the other side surface (side surface opposite to the gas supply portion 8) of the airtight chamber 4 9 is discharged out of the hermetic chamber 4.

The inert gas supply condition is preferably 0.5 to 40 m ³ / hr. Further, the discharge port 9 is preferably connected to an exhaust device (not shown). By connecting in this way, water vapor can be efficiently excluded.

  In FIG. 1, reference numeral 10 denotes an aqueous solution tank. An aqueous solution 11 of a monomer mixture housed in the tank is sent to a mixer 13, mixed with a photopolymerization initiator sent from a polymerization initiator tank 12, and then supplied to a supply pipe. 14 is supplied into the liquid reservoir 100 on the upstream side in the moving direction of the resin belt 1 to form an aqueous solution layer 15 of the monomer mixture. At this time, the supply amount of the aqueous solution of the monomer mixture is adjusted so that the liquid depth of the aqueous solution layer 15 of the monomer mixture becomes a target depth. According to this aspect, it is possible to polymerize an aqueous solution of a monomer mixture having a liquid depth of preferably 5 mm or more, more preferably 10 to 200 mm.

  The aqueous solution of the monomer mixture supplied on the resin belt 1 is transported downstream as the belt 1 moves, and is irradiated with light from the light sources 7a and 7b. As the light source, commercially available products that can be irradiated with ultraviolet light and visible light, which are usually used as light sources for photopolymerization, can be used as appropriate.

  In this way, the aqueous solution layer 15 of the monomer mixture conveyed on the downstream side while being polymerized on the resin belt 1 is unloaded through the most downstream portion of the hermetic chamber 4 in a state where the polymerization is completed, and near the roller 3. Is peeled off from the resin belt 1. Reference numeral 16 denotes a water-containing polymer sheet that is peeled and continuously recovered. The manufactured sheet of partially neutralized poly (meth) acrylic acid can be cut, ground and dried according to a conventional method to obtain a powder product. The degree of pulverization of the powder product is preferably about 83 mesh pass.

  The viscosity of the 0.2% by weight aqueous solution of the poly (meth) acrylic acid partial neutralized product of the present invention produced as described above at 20 ° C. is about 200 to 700 mPa · s, preferably 300 to 600 mPa · s. s. When the viscosity of the 0.2% by weight aqueous solution is less than 200 mPa · s or more than 700 mPa · s, workability when using a partially neutralized poly (meth) acrylic acid in an aqueous solution is remarkably reduced. The viscosity of the 0.2% by weight aqueous solution means that the poly (meth) acrylic acid partial neutralized product is sufficiently dissolved in water and allowed to stand for 24 hours from the start of dissolution so that the viscosity becomes constant. This is a value measured under the conditions of 20 ° C. and 30 rpm with a BM viscometer manufactured by Tokyo Keiki.

Furthermore, the poly (meth) acrylic acid partial neutralized product of the present invention is characterized in that it does not cause significant fluctuations in viscosity when used as an aqueous solution, unlike conventional poly (meth) acrylic acid partially neutralized products. is doing. Specifically, it has the following physical properties.
(1) Viscosity A at 20 ° C. after stirring a mixed solution of 0.2% by weight of a partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerin, and 93.1% by weight of water for 15 seconds is 200 to 200 ° C. 800 mPa · s (preferably 300 to 700 mPa · s),
(2) Viscosity B at 20 ° C. after stirring a mixed liquid of 0.2% by weight of partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerin, and 93.1% by weight of water for 20 minutes is 200 to 200 ° C. 800 mPa · s (preferably 300 to 700 mPa · s), and (3) the ratio of viscosity B to viscosity A (B / A) is 0.8 to 1.2 (preferably 0.85 to 1. 15).

  It can be seen that the partially neutralized poly (meth) acrylic acid of the present invention has a very small difference between the viscosity immediately after the aqueous solution and the viscosity after stirring for a certain time. In other words, the viscosity of the aqueous solution becomes almost constant without being affected by the stirring time. This is because the partially neutralized poly (meth) acrylic acid of the present invention is excellent in solubility and dispersibility in water, and thus becomes a uniform aqueous solution quickly. Thereby, industrial handling becomes easy and workability is dramatically improved.

  In a conventional glycerin aqueous solution of 0.2% by weight of a partially neutralized poly (meth) acrylic acid, when the viscosity A exceeds 1000 mPa · s, the workability is remarkably lowered due to, for example, an increase in the initial viscosity. It was. However, the partially neutralized poly (meth) acrylic acid obtained by the production method of the present invention is 0.2% by weight glycerin even when the 0.2% by weight aqueous solution viscosity is relatively high at 450 to 600 mPa · s. Since the viscosity A after 15 seconds of the aqueous solution is sufficiently low as 600 to 800 mPa · s and the viscosity variation with time is small, it can be expected to improve the workability and reduce the defective rate of the poultice manufacturer.

  In general, when preparing an aqueous solution of a partially neutralized poly (meth) acrylic acid, a so-called “mako” is produced by the method of adding a powder polymer to water. Even if the stirring intensity and the stirring mode are changed, the “mamako” is not dispersed, but remains in the 0.2% aqueous solution as a highly concentrated polymer aggregate swollen in the “mamako” state. .

  As described above, even when 0.2% aqueous solution is used, a local concentration distribution is generated. Immediately after the adjustment, the 0.2% aqueous solution viscosity often shows a high viscosity measurement value, and the local concentration distribution. Therefore, the measurement accuracy of viscosity is lowered. Therefore, as described above, 6.7% by weight of glycerin is added to the aqueous solution to improve the uniform dispersibility of the poly (meth) acrylic acid partial neutralized product in water, thereby suppressing so-called “mako”. Thus, the viscosity measurement accuracy is improved. In addition, the fact that partially neutralized poly (meth) acrylic acid is often used by being dissolved in a mixed solution of glycerin and water having the above-described composition in its processing step (for example, a poultice preparation step). Exists. For these reasons, the viscosity was measured based on a mixed solution of 0.2% by weight of a partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerin, and 93.1% by weight of water.

  The above-mentioned viscosities A and B are values measured under the conditions of 20 ° C. and 30 rpm with a BM viscometer manufactured by Tokyo Keiki Co., Ltd. Specifically, a partially neutralized poly (meth) acrylic acid was first added to glycerin, stirred for 30 seconds, then water was added, and after stirring for 15 seconds and after 20 minutes, BM manufactured by Tokyo Keiki Co., Ltd. It is a value measured with a mold viscometer under the conditions of 20 ° C. and 30 rpm.

  The average molecular weight of the partially neutralized poly (meth) acrylic acid of the present invention is not particularly limited, but is usually preferably 1 million or more, more preferably 5 million or more.

  Hereinafter, the present invention will be described in detail by way of examples. In addition, the description of% simply means weight%.

Example 1
As a reaction vessel, an aqueous solution of a monomer mixture containing 98% acrylic acid 141 g, 36% sodium acrylate 482 g, and pure water 417 g was added to a polypropylene tray as a reaction tank, and the temperature of the aqueous solution was maintained at 10 ° C. with nitrogen. Expelled dissolved oxygen. Then, under a nitrogen stream, 2,1′-azobis (2-methylpropionamidine) dihydrochloride 0.31 g (1000 ppm with respect to the monomer), 2-mercaptoethanol 0.0031 g (with respect to the monomer) 10 ppm) was diluted with pure water to make a 1% aqueous solution, and this was added to prepare an aqueous solution of the monomer mixture.

Next, 28 100 mW light emitting diodes (product name: NCCU033E manufactured by Nichia Corporation) having an emission wavelength of 357 to 377 nm and a maximum center wavelength of 365 nm are used, and the thickness is 5 mm. UV illuminance is 0.4 mW / cm ² (Ushio Electric Co., Ltd. UV illuminance meter UIT-150 (UVD-S365)) through borosilicate glass (Corning, product name: Pyrex). The polymerization was initiated by irradiating an aqueous solution of the monomer mixture.

After 13 minutes from the start of irradiation, after the polymerization temperature reached a peak, switch to a Toshiba-made black light mercury lamp that radiates 300 to 450 nm, and irradiate it with ultraviolet illuminance of 6 mW / cm ² for 30 minutes. Got. The water-containing gel material was chopped, dried and pulverized to obtain a powder.

  The viscosity of the resulting partially neutralized polyacrylic acid was measured as follows. The measurement results are shown in Table 1.

<Measurement of 0.2% aqueous solution viscosity>
In a 500 ml conical beaker, 399.2 g of pure water was added, 0.8 g of partially neutralized polyacrylic acid was added, and the mixture was stirred for 2 hours with a magnetic stirrer. It was left for 24 hours in a thermostatic bath. The viscosity of the adjustment liquid was measured with a B-type viscometer under the conditions of 20 ° C. and 30 rpm.

<Measurement of 0.2% glycerin aqueous dispersion solution viscosity>
10 g of glycerin was put into a 500 ml beaker, and then 0.3 g of partially neutralized polyacrylic acid was added and stirred for 30 seconds. Thereafter, 140 g of pure water was added and stirred for 15 seconds to prepare a dispersion of 0.2 wt% polyacrylic acid partially neutralized product, 6.7 wt% glycerin, and 93.1 wt% pure water. The viscosity of the adjustment liquid was measured with a B-type viscometer under the conditions of 20 ° C. and 30 rpm.

  Then, stirring was continued at 150 rpm with a jar tester, and after 10 minutes and 20 minutes, the viscosity was measured with a B-type viscometer under the conditions of 20 ° C. and 30 rpm.

<Calculation method of change with time of viscosity of 0.2% glycerin aqueous dispersion>
Change with time = (viscosity after 20 minutes / viscosity after 15 seconds)

Example 2
An aqueous monomer mixture solution was prepared in the same manner as in Example 1.

Next, using a Toshiba black light fluorescent lamp that emits ultraviolet rays having an emission wavelength of 300 to 450 nm and a peak wavelength of 352 nm, the ultraviolet illuminance is 0.4 mW / g through a 5 mm thick borosilicate glass. The polymerization was started by irradiating the aqueous solution of the monomer mixture so as to be cm ² .

After the polymerization temperature reached its peak, it was switched to a Toshiba black light mercury lamp having an emission wavelength of 300 to 450 nm and irradiated for 30 minutes to obtain an ultraviolet illuminance of 0.4 mW / cm ² to obtain a hydrogel material. The hydrogel material was pulverized, dried and pulverized to obtain a powder.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 2.

Example 3
In Example 1, the same operation as in Example 1 was performed, except that the first exposure was changed to a Toshiba black light fluorescent lamp emitting 300 to 450 nm having a peak wavelength of 352 nm. As a result, the polymerization temperature reached a peak 18 minutes after the start of exposure.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 3.

Example 4
In Example 3, the same operation as in Example 3 was performed except that the initial ultraviolet illuminance was changed to 0.6 mW / cm ² . As a result, the polymerization temperature reached a peak after 14 minutes from the start of exposure.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 4.

Example 5
In Example 1, the same operation as in Example 1 was performed except that the first exposure was changed to a fluorescent lamp for capturing insects and for photochemistry that emits 300 to 580 nm having a peak wavelength of 360 nm. As a result, the polymerization temperature reached a peak 18 minutes after the start of exposure.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 5.

Example 6
On a belt of a belt conveyor as shown in FIG. 1, a 30% aqueous solution of acrylic acid / sodium acrylate (50/50 mol%, monomer), 1000 ppm of 2,2′-azobis (2 -Methylpropionamidine) dihydrochloride and a mixed solution of 10 ppm 2-mercaptoethanol with respect to the monomer were continuously supplied at a constant rate. The mixed liquid is conveyed on a conveyor, and in the first half of the conveyor, ultraviolet light of 0.4 mW / cm ² is used using a black light fluorescent lamp manufactured by Toshiba Lighting & Technology via a borosilicate glass (Tempax manufactured by Schott Corp.) having a thickness of 5 mm. Was irradiated. The latter half of the conveyor was irradiated with ultraviolet rays in the same manner as in the first half so as to be ² mW / cm ² .

  As a result, a water-containing gel-like substance having a thickness of 18 mm continuous from the conveyor outlet portion was obtained. The hydrogel material was pulverized, dried and pulverized to obtain a powder.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The results are shown in Table 6.

Comparative Example 1 (Soda glass is used for photopolymerization)
A partially neutralized polyacrylic acid was produced in the same manner as in Example 1 except that the light transmissive material was changed to 5 mm tempered glass (soda lime glass).

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 7.

Comparative Example 2 (using redox polymerization reaction)
As a reaction vessel, an aqueous solution of a monomer mixture containing 98 g of 98% acrylic acid, 694 g of 36% sodium acrylate and 600 g of pure water was added to a stainless steel dewar, and the temperature of the aqueous solution was kept at 10 ° C. while maintaining the temperature of the aqueous solution at 10 ° C. And expelled dissolved oxygen. Then, under a nitrogen stream, 0.0135 g of t-butyl hydroperoxide, 0.135 g of sodium formate, 0.0675 g of sodium persulfate, and 0.027 g of sodium erythorbate were charged and left for 12 hours to leave a hydrogel material. Got. Thereafter, the hydrogel material was pulverized, dried and pulverized to obtain a powder.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The measurement results are shown in Table 8.

Comparative Example 3
In Example 1, the first exposure was changed to Philips TL20W / 01RS that selectively irradiates ultraviolet rays having a wavelength of 311 to 312 nm, and irradiation was performed with an ultraviolet illuminance of 0.06 mW / cm ² . The polymerization temperature reached a peak 28 minutes after the start of irradiation. Then, irradiation was continued for 30 minutes with the ultraviolet illuminance as it was, to obtain a hydrogel material. The hydrogel material was pulverized, dried and pulverized to obtain a powder.

  The obtained partially neutralized polyacrylic acid was measured in the same manner as in Example 1. The results are shown in Table 9.

  As described above, the time-dependent changes in the 0.2% glycerin aqueous dispersion viscosity in the examples are both 0.89 or more, and the viscosity of the aqueous solution can be substantially constant without being affected by the stirring time. It became clear. On the other hand, the time-dependent change in the viscosity of the 0.2% glycerin aqueous dispersion in the comparative example was less than 0.8, indicating that the viscosity change with time was large.

  Therefore, it is clear that the polyacrylic acid partial neutralized products of the examples are excellent in water solubility and dispersibility, and workability is greatly improved.

  The partially neutralized poly (meth) acrylic acid of the present invention is excellent in solubility in water and dispersibility, and is excellent in handling in an aqueous solution. It is useful for dispersants such as various pigments, scale inhibitors, cleaning builders, thickeners, binders, pharmaceutical poultices and bases for haptic agents, and is used in various fields.

It is a schematic side view which shows an example of the manufacturing apparatus of the poly (meth) acrylic acid partial neutralized material of this invention. FIG. 2 is a cross-sectional view taken along line P-P ′ in FIG. 1.

Explanation of symbols

1 Resin belt 2, 3 Roller 4 Airtight chamber 5 Upper surface (light transmissive material)
7a, 7b Light source 8 Inert gas supply unit 9 Gas outlet 10 Aqueous solution tank 11 Monomer aqueous solution 12 Polymerization initiator tank 13 Mixer 14 Supply pipe 15 Monomer aqueous solution layer 16 Hydrous poly (meth) acrylic acid partial neutralization Material layer 100 Liquid reservoir

Claims (10)

  In the presence of a photopolymerization initiator, an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate is irradiated with light containing ultraviolet rays to photopolymerize the monomer mixture to produce poly ( A method for producing a partially neutralized (meth) acrylic acid, wherein a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm is provided between a light source and an aqueous solution of the monomer mixture. A method for producing a partially neutralized poly (meth) acrylic acid, which comprises irradiating with light.   The manufacturing method of Claim 1 which irradiates light to the aqueous solution of the said monomer mixture in inert gas atmosphere.   The manufacturing method according to claim 1, wherein the light transmissive material is borosilicate glass or quartz glass.   The production method according to claim 1, 2, or 3, wherein the monomer mixture is continuously photopolymerized on a movable belt.   The light source is at least one selected from the group consisting of light-emitting diodes, fluorescent lamps for insect traps and photochemistry, fluorescent blue lamps, metal halide lamps, high-pressure mercury lamps, black light fluorescent lamps, black light mercury lamps, and black light bulb-type fluorescent lamps. It is a seed | species, The manufacturing method in any one of Claims 1-4.   The manufacturing method according to any one of claims 1 to 5, wherein a light source having a wavelength of irradiation light in a range of 357 to 377 nm is used.   The poly (meth) acrylic acid partial neutralized product manufactured by the manufacturing method in any one of Claims 1-6. A poly (meth) acrylic acid partial neutralized product comprising a monomer containing (meth) acrylic acid and (meth) acrylate as a structural unit and having the following physical properties:
(1) Viscosity at 20 ° C. after stirring a mixed solution of 0.2% by weight of the partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerol and 93.1% by weight of water for 15 seconds (A) Is in the range of 200 to 800 mPa · s,
(2) Viscosity at 20 ° C. after stirring a mixed solution of 0.2% by weight of the partially neutralized poly (meth) acrylic acid, 6.7% by weight of glycerin and 93.1% by weight of water at 20 ° C. (B) Is in the range of 200 to 800 mPa · s, and (3) the ratio of the viscosity B to the viscosity A (B / A) is in the range of 0.8 to 1.2.   An apparatus for producing a partially neutralized poly (meth) acrylic acid, a reaction vessel containing an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate, and a gas containing the reaction vessel A light source that irradiates light including ultraviolet light outside the hermetic chamber and above the hermetic chamber is formed, and the upper surface of the hermetic chamber is formed of a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm. A device characterized by that.   A unit for continuously producing a partially neutralized poly (meth) acrylic acid, and supplying an aqueous solution of a monomer mixture containing (meth) acrylic acid and (meth) acrylate to a movable belt A body mixture supply unit, a movable belt having a liquid reservoir for containing an aqueous solution of the monomer mixture, a hermetic chamber for photopolymerization disposed along the traveling direction of the movable belt, and the airtight chamber A light source for irradiating light including ultraviolet light is provided above the outside, and the upper surface of the hermetic chamber is formed of a light transmissive material having an ultraviolet transmittance of 80% or more in a wavelength range of 330 to 370 nm. apparatus.

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