JP2003177121A - Method for evaluating cationic resin-modified silica dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating a cationic resin-modified silica dispersion for ascertaining performance of the dispersion before using the cationic resin-modified silica dispersion as a raw material of coating liquid or the like, and for facilitating production control even when the conditions of manufacturing or preservation changes. <P>SOLUTION: In the method for evaluating the cationic resin-modified silica dispersion, the cationic resin-modified silica dispersion is evaluated by the ratio of desorption of cationic resin, which is desorbed from the surfaces of silica particles, in the cationic resin-modified silica dispersion in which silica and the cationic resin are dispersed in polar solvent. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for ink jet recording paper (hereinafter, also simply referred to as a coating liquid), a filler for newsprint, an abrasive and the like. The present invention relates to a method for evaluating a cationic resin-modified silica dispersion useful for the preparation of a dispersion. In detail, even if manufacturing or storage conditions change, before using as a raw material such as a coating liquid using a cationic resin-modified silica dispersion, the performance of the dispersion is determined to facilitate production control. Provided is a method for evaluating a cationic resin-modified silica dispersion. [0002] Conventionally, a cationic resin-modified silica dispersion in which silica and a cationic resin are dispersed in a polar solvent has been used as a coating liquid for ink jet recording paper. [0003] The cationic resin-modified silica dispersion is prepared by adding various additives in addition to a water-soluble polymer as a binder when preparing a coating liquid. In addition, there is a problem that it is difficult to prepare a stable coating liquid with good reproducibility due to differences in production conditions and the like. As a remedy, a method for producing a cationic resin-modified silica dispersion liquid in which silica and a cationic resin are dispersed in a polar solvent and then aged for a specific period has been proposed (JP-A-2001-207078). [0004] However, even when a coating liquid is prepared using a cationic resin-modified silica dispersion obtained by aging, the aging conditions of the silica dispersion or the aging conditions after the aging. However, depending on the storage conditions, when the recording liquid for inkjet is manufactured using the coating liquid, there is a problem that the water resistance of the recording paper may be lowered due to the deterioration of the performance of the coating liquid. Was. Further, even if an attempt is made to set usable conditions of the silica dispersion so that the performance of the coating liquid using the cationic resin-modified silica dispersion does not decrease, there is no index for setting, and the cationic resin-modified silica is not used. There is also a problem that production control of the dispersion liquid and the recording paper for inkjet is difficult. Accordingly, an object of the present invention is to evaluate whether or not the performance as a coating liquid has decreased when a coating liquid has been prepared, in the state of the cationic resin-modified silica dispersion,
It is an object of the present invention to provide a method for evaluating a cationic resin-modified silica dispersion liquid which facilitates production control of the cationic resin-modified silica dispersion liquid and ink jet recording paper. [0006] By setting an index for evaluating the performance of the cationic resin-modified silica dispersion, even if the production or storage conditions change, when a coating liquid is prepared using the silica dispersion, the performance decreases. Unavailable silica dispersion can be determined, and production control becomes easy. [0007] The present inventors have conducted intensive studies on the above problems. As a result, in the cationic resin-modified silica dispersion, the cationic surface is assumed to have been adsorbed on the surface of the anionic silica particles by an electric action and the silica particle surface has been modified from anionic to cationic. It has been found that after the resin is once adsorbed on the surface of the silica particles, it is desorbed according to the aging conditions after the dispersion of the silica dispersion and the storage conditions during storage. As a result of further study based on such knowledge, the cationic resin desorption ratio and the water resistance of the inkjet recording paper produced by applying a coating liquid prepared using the cationic resin-modified silica dispersion were coated. It was found that there was a correlation between the dispersions, and the performance of the silica dispersion as a coating liquid was evaluated without preparing the cationic resin-modified silica dispersion as a coating liquid. The inventors succeeded in determining the cationic resin-modified silica dispersion liquid which did not decrease, and completed the present invention. [0008] Here, the cationic resin desorption ratio refers to the amount of silica contained in the cationic resin-modified silica dispersion before the evaluation after the dispersion of the silica dispersion is completed. It is the ratio of the amount of the cationic resin detached from the particle surface. That is, the present invention provides a method for evaluating a cationic resin-modified silica dispersion in a cationic resin-modified silica dispersion obtained by dispersing silica and a cationic resin in a polar solvent, based on the cationic resin desorption ratio. This is a method for evaluating a characteristic cationic resin-modified silica dispersion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The cationic resin-modified silica dispersion to be evaluated by the method of the present invention is a cationic resin-modified silica dispersion in which silica and a cationic resin are dispersed in a polar solvent. The silica of the cationic resin-modified silica dispersion is a known silica such as dry silica, wet silica, sol-gel method silica, and colloidal silica, and is not particularly limited. The above-mentioned fumed silica is obtained by burning a silane-based gas such as silicon tetrachloride in an oxyhydrogen flame, and is also called “fumed silica”. In general,
Dry silica having a specific surface area in the range of 30 to 500 m ² / g is available, and can be suitably used for a cationic resin-modified silica dispersion. [0013] The wet silica is typically silica obtained by a precipitation method in which silica is precipitated in a solution by neutralizing sodium silicate with a mineral acid, and is also called white carbon. Similarly, gel silica produced by neutralizing sodium silicate with an acid can also be used. As the wet-process silica, a dehydrated silica cake which is not subjected to a drying step after filtration and washing after the neutralization reaction can be directly used. Further, the sol-gel method silica is obtained by hydrolyzing a silicon alkoxide such as tetramethoxysilane or tetraethoxysilane in an acidic or alkaline aqueous organic solvent. Further, the above-mentioned colloidal silica is generally obtained by passing an aqueous solution of sodium silicate through a cation exchange resin to form a silica sol, and then aging the sol by heating to grow particles. The silica in the cationic resin-modified silica dispersion has an excellent ink absorbency when used in a coating liquid and can be suitably used in the field of ink jet recording paper and the like. Is preferably in the range of 1 to 50 nm, and the average aggregated particle diameter is in the range of 10 to 1000 nm. The cationic resin used in the cationic resin-modified silica dispersion is not particularly limited as long as it is a known cationic resin, and dissociates when dissolved in water to exhibit cationicity. Among them, resins having primary to tertiary amine groups or quaternary ammonium groups are preferred. Specific examples include polyethyleneimine, polyvinylpyridine, polyamine sulfone, polydialkylaminoethyl methacrylate, polydialkylaminoethyl acrylate, polydialkylaminoethyl methacrylamide, polydialkylaminoethyl acrylamide, polyepoxyamine, polyamideamine, dicyandiamide -Formalin condensate, dicyandiamide polyalkyl-
Polyalkylene polyamine condensate, polyvinylamine,
Compounds such as polyallylamine and hydrochlorides thereof, and polydiallyldimethylammonium chloride and copolymers of diallyldimethylammonium chloride and acrylamide, polydiallylmethylamine hydrochloride, polymethacrylate methyl chloride quaternary salt and the like. Can be. The polar solvent of the cationic resin-modified silica dispersion is not particularly limited as long as the polar solvent disperses the silica and the cationic resin easily. Water is most preferred as such a polar solvent. Of course, other than water, polar solvents such as alcohols such as methanol, ethanol and isopropyl alcohol, ethers and ketones may be used, and a mixed solvent of water and the above polar solvent is also suitable. In order to improve the stability and dispersibility of the silica particles and the storage stability of the silica dispersion, a small amount of a surfactant or a fungicide may be added. In the cationic resin-modified silica dispersion, the concentration of silica in the cationic resin-modified silica dispersion is not particularly limited as long as it can be used for preparing a coating solution.
Generally, the concentration is 10% by weight or more. The amount of the cationic resin is 2 to 5 with respect to 100 parts by weight of silica.
It is preferably 0 parts by weight, particularly preferably 2 to 10 parts by weight. The higher the zeta potential, which is an index of the surface charge of the particles in the cationic resin-modified silica dispersion, the higher the water resistance of the ink jet recording paper, the more it is +10 mV or more, preferably +20 mV.
V or more, more preferably +30 mV or more. The cationic resin-modified silica dispersion may be produced by any method, but is generally produced by the following dispersion method. That is, after adding silica and a cationic resin to a polar solvent and mixing them, a disperser such as a turbine / stator type high-speed rotary stirring / dispersing machine such as a homogenizer, a colloid mill, an ultrasonic emulsifier, or a high-pressure homogenizer is used. And then finely dispersing and mixing to obtain a cationic resin-modified silica dispersion. When used in a coating liquid for ink jet recording paper, among them, a high pressure homogenizer may be used to face and collide at a processing pressure of 300 kgf / cm ² or more,
Or the differential pressure between the inlet and outlet of the orifice is 300kg
A cationic resin-modified silica dispersion obtained by a method of finely dispersing and mixing by passing through an orifice under the condition of f / cm ² or more is most preferable. At this time, the silica may be used in the form of a powder or a silica slurry finely dispersed in a polar solvent such as water in advance. By the way, as described above, the present inventors have found that the cationic resin in the cationic resin-modified silica dispersion is once adsorbed on the surface of the silica particles, and then the aging conditions after the dispersion of the silica dispersion are obtained. Desorption according to storage conditions during storage, the cationic resin desorption ratio calculated from this desorption amount, for inkjet manufactured by applying a coating liquid prepared using a cationic resin-modified silica dispersion It was found that there was a correlation between the water resistance of the recording paper. When the cationic resin desorption ratio increases, the water resistance of the ink jet recording paper produced by applying the coating liquid prepared using the silica dispersion decreases,
When the cationic resin desorption ratio was low, a phenomenon in which the water resistance increased was observed. The amount of the cationic resin desorbed from the silica particle surface in the cationic resin-modified silica dispersion tends to increase as the number of days passes when the silica dispersion is aged or stored at a constant temperature. Also, the higher the aging or storage temperature, the more the amount of desorption tends to increase. As described above, the cationic resin in the cationic resin-modified silica dispersion liquid is adsorbed on the surface of the anionic silica particles by electric action, and the surface of the silica particles is modified from anionic to cationic. It is estimated that It is unclear why the higher the aging or storage temperature of the cationic resin-modified silica dispersion or the longer the number of days, the greater the amount of cationic resin detached from the silica particle surface in the silica dispersion. However, since an anionic compound is generally used as an ink for inkjet, the cationic resin detachment ratio, that is, the amount of the cationic resin contained in the cationic resin-modified silica dispersion is When the ratio of the amount of the cationic resin desorbed from the surface of the silica particles was increased before the evaluation after the dispersion of the silica dispersion was completed, the coating solution using the silica dispersion was applied. It is presumed that the portions having cationicity in the coating layer of the inkjet recording paper vary, and that the water resistance of the coating layer is reduced. Therefore, even if the aging or storage conditions of the cationic resin-modified silica dispersion are changed, if the cationic resin desorption ratio is controlled as an index value, the coating liquid prepared using the silica dispersion can be used. The problem of reduced water resistance of the ink jet recording paper manufactured by coating can be avoided. When the cationic resin detachment ratio measured for the cationic resin-modified silica dispersion is lower than the value of the cationic resin detachment ratio set as an index value, the coating liquid prepared using the silica dispersion is used. Can avoid the problem of reduced water resistance in inkjet recording paper manufactured by applying the ink, and conversely, if the water resistance is high, water resistance is applied to the inkjet recording paper manufactured by applying a coating liquid prepared using the silica dispersion. It can be determined that the problem of reduction occurs. In the present invention, the method for measuring the cationic resin desorption ratio is not particularly limited, but after the dispersion of the cationic resin-modified silica dispersion and at the time of evaluation, the silica dispersion is centrifuged, and the colloid titration method is performed. Is preferable to measure the amount of the cationic resin contained in the supernatant and calculate the cationic resin desorption ratio. The value of the cationic resin desorption ratio, which is an index of a decrease in the water resistance of the cationic resin-modified silica dispersion, differs depending on the type of raw silica used, such as dry silica, wet silica, and sol-gel method. Generally, the density of surface silanol groups present on the silica surface varies depending on the type of silica. Due to this effect, it is estimated that the cationic resin desorption ratio, which is an index of a decrease in water resistance, differs depending on the raw material silica. In the present invention, the cationic resin desorption ratio calculated from the cationic colloid equivalent value, which is an index for evaluating the performance of the cationic resin-modified silica dispersion, is, for example, the cationic resin-modified silica using dry silica. If the silica dispersion is 2.5% or less, the problem of reduced water resistance is unlikely to occur in ink jet recording paper produced by applying a coating liquid prepared using the silica dispersion. Therefore,
The index value for managing the performance of the cationic resin-modified silica dispersion is preferably 2.5%, more preferably 2.0%. As will be understood from the above description, the method for evaluating a cationic resin-modified silica dispersion according to the present invention provides a method for preparing a cationic resin-modified silica dispersion in the form of a cationic resin-modified silica dispersion. Since the water resistance can be evaluated when the coating liquid prepared by using the above is applied to obtain an inkjet recording paper,
Even if the production or storage conditions change, it is possible to produce an inkjet recording paper having good water resistance, and the production management of the cationic resin-modified silica dispersion and the inkjet recording paper becomes easy. EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. The following method was used to measure the cationic resin detachment ratio in the cationic resin-modified silica dispersion and to evaluate the performance of the silica dispersion. (Measurement of Cationic Resin Desorption Ratio) For the cationic resin-modified silica dispersion immediately after dispersion and immediately before preparation of the coating liquid,
Colloid titration was performed by the following method. 250 g of a cationic resin-modified silica dispersion
Was centrifuged at 16,500 rpm for 120 minutes using a centrifugal separator (Model 3630, manufactured by Sigma). After adding 3 drops of toluidine blue indicator solution (manufactured by Wako Pure Chemical Industries, Ltd.) to 25 g of the supernatant obtained from the centrifugation, N / N was added.
The titration was performed using a 400 polyvinyl potassium sulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.). The time when the color of the measurement liquid changed from blue to pink and the state was maintained for 10 seconds was defined as the end point. The titer at this time was defined as a supernatant drop titer S1 (ml). Next, the cationic resin concentration of the same cationic resin used in the cationic resin-modified silica dispersion was 25.
After adding 3 drops of toluidine blue indicator solution (manufactured by Wako Pure Chemical Industries, Ltd.) to 25 g of 0 ppm aqueous solution, titration was performed with an N / 400 polyvinyl potassium sulfate solution (manufactured by Wako Pure Chemical Industries, Ltd.). The time when the color of the measurement liquid changed from blue to pink and the state was maintained for 10 seconds was defined as the end point. The titer at this time was defined as a cationic resin titer S2 (ml). Finally, titration was performed in the same manner using 25 g of pure water instead of the above-mentioned cationic resin aqueous solution. The titer at this time was defined as a blank titer SB (ml). Using the following formulas (1) to (3), the cationic resin not adsorbed on the silica surface contained in 1 g of the cationic resin-modified silica dispersion immediately after dispersion and immediately before preparation of the coating liquid was used. The amount of resin was determined, and the cationic resin desorption ratio was calculated according to equation (4). ## EQU1 ## [Mathematical formula-see original document] [Mathematical formula-see original document] [Mathematical formula-see original document] (Evaluation of Performance of Cationic Resin-Modified Silica Dispersion)
The evaluation was performed by evaluating the water resistance of an inkjet recording paper coated with a coating liquid using a cationic resin-modified silica dispersion. The recording paper for ink jet was prepared by the following method. Dry Silica Dispersion Modified with Cationic Resin 10
0 g and 100 g of a 10% aqueous solution of polyvinyl alcohol were stirred and mixed with a propeller mixer to obtain a coating liquid. The obtained coating liquid was applied on a surface of a commercially available high-quality paper with a bar coder so that the coating amount became 20 g / m ² , and dried to prepare an ink jet recording paper. The water resistance of the ink jet recording paper was evaluated by the following method. Epson inkjet printer PM7
Character printing was performed with magenta ink using 00C, and the printed recording paper was immersed in water, and after 30 seconds, the printed characters bleeding caused by the ink flowing out were visually observed. ：: Character bleeding is hardly observed. Δ: Blurring of several characters is observed. ×: Character bleeding is observed at several tens or more places. Example 1 Dry silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama Co., Ltd.)
While gradually adding 480 g of Reolosil QS-30 to 1848 g of pure water, maintaining the liquid temperature at 30 ° C., an ultramixer (Ultramixer LR- manufactured by Mizuho Kogyo) was used.
By dispersing in 2), a dry silica dispersion was obtained.
While adding this dry silica dispersion to 72 g of an aqueous diallyldimethylammonium chloride polymer solution (cationic resin concentration: 20% by weight), the liquid temperature was maintained at 30 ° C., and an ultramixer (Ultramixer LR-2, manufactured by Mizuho Kogyo) was used. ) To obtain a premixed liquid.
This pre-mixed liquid was treated with a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) at a processing pressure of 80%.
The dispersion was passed through the orifice once at 0 kgf / cm ² to perform a dispersion treatment, thereby obtaining a cationic resin-modified silica dispersion. The resulting cationic resin-modified silica dispersion was transferred to a polyethylene (PE) container and stored for 30 days at a storage temperature of 25 ° C. Comparative Example 1 A cationic resin-modified silica dispersion was prepared and stored in the same manner as in Example 1 except that the storage conditions were storage temperature of 35 ° C. and storage days of 50 days. Comparative Example 2 A cationic resin-modified silica dispersion was prepared and stored in the same manner as in Example 1 except that the storage conditions were a storage temperature of 40 ° C. and storage days of 10 days. Example 2 Dry silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama Co., Ltd.)
While gradually adding 480 g of Reolosil QS-30 to 1848 g of pure water, maintaining the liquid temperature at 30 ° C., an ultramixer (Ultramixer LR- manufactured by Mizuho Kogyo) was used.
By dispersing in 2), a dry silica dispersion was obtained.
While adding this dry silica dispersion to 72 g of an aqueous diallyldimethylammonium chloride polymer solution (cationic resin concentration: 20% by weight), the liquid temperature was maintained at 30 ° C., and an ultramixer (Ultramixer LR-2, manufactured by Mizuho Kogyo) was used. ) To obtain a premixed liquid.
This pre-mixed liquid was treated with a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) at a processing pressure of 80%.
The dispersion was passed through the orifice once at 0 kgf / cm ² to perform a dispersion treatment, thereby obtaining a cationic resin-modified silica dispersion. The resulting cationic resin-modified silica dispersion was aged at an aging temperature of 30 ° C. for 15 days, and then transferred to a PE container.
It was stored for 15 days in an environment at a storage temperature of 15 ° C. Example 3 Dry silica having a specific surface area of 140 m ² / g (manufactured by Tokuyama Co., Ltd.)
While slowly adding 480 g of Reolosil QS-10 to 1848 g of pure water, maintaining the liquid temperature at 30 ° C., an ultramixer (Ultramixer LR- manufactured by Mizuho Kogyo) was used.
By dispersing in 2), a dry silica dispersion was obtained.
While adding this dry silica dispersion to 72 g of an aqueous diallylmethylamine hydrochloride polymer solution (cationic resin concentration: 20% by weight), the liquid temperature was maintained at 30 ° C., and an ultramixer (Ultramixer LR-, manufactured by Mizuho Industry Co., Ltd.) was used. A premix was obtained by mixing in 2). The pre-mixed liquid was treated with a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) at a processing pressure of 800 kgf / cm.
^{In step 2} , the dispersion was passed through the orifice once to obtain a dispersion of a cationic resin-modified silica. Transfer the resulting cationic resin-modified silica dispersion to a PE container,
It was stored for 30 days in an environment at a storage temperature of 15 ° C. Comparative Example 3 A cationic resin-modified silica dispersion was prepared and stored in the same manner as in Example 3, except that the storage conditions were a storage temperature of 40 ° C. and a storage period of several 10 days. Example 4 Dry silica having a specific surface area of 220 m ² / g (manufactured by Tokuyama Co., Ltd.)
While gradually adding 480 g of Reolosil QS-20 to 1867 g of pure water, the liquid temperature was maintained at 30 ° C., and an Ultramixer (Ultramixer LR-, manufactured by Mizuho Industry Co., Ltd.) was used.
By dispersing in 2), a dry silica dispersion was obtained.
While adding this dry silica dispersion to 53 g of an aqueous diallyldimethylammonium chloride polymer solution (cationic resin concentration: 20% by weight), the liquid temperature was maintained at 30 ° C., and an ultramixer (Ultramixer LR-2, manufactured by Mizuho Kogyo) was used. ) To obtain a premixed liquid.
This pre-mixed liquid was treated with a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer, LA-31) at a processing pressure of 80%.
The dispersion was passed through the orifice once at 0 kgf / cm ² to perform a dispersion treatment, thereby obtaining a cationic resin-modified silica dispersion. The resulting cationic resin-modified silica dispersion is subjected to PE
It was transferred to a container and stored for 30 days in an environment at a storage temperature of 15 ° C. Comparative Example 4 A cationic resin-modified silica dispersion was prepared and stored in the same manner as in Example 3, except that the storage conditions were a storage temperature of 40 ° C. and a storage period of several tens of days. Using the cationic resin silica dispersions obtained in the above Examples and Comparative Examples, recording paper for ink jet was prepared and evaluated for water resistance. Table 1 shows the obtained results. Similarly, in the above Examples and Comparative Examples, the amount of the cationic resin not adsorbed on the silica particles in the cationic resin-modified silica dispersion immediately after the production,
The amount of the cationic resin not adsorbed on the silica particles in the silica dispersion immediately before producing the coating liquid was measured, and the cationic resin desorption ratio was determined. Table 1 shows the obtained results. [Table 1]

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 2G042 AA01 AA05 BD18 BD20 BE05                       BE10 CA10 CB04 DA02 DA08                       EA02 EA20 FA12 FA20 GA10                       HA10                 4J037 AA18 CA08 CB04 CB07 CB08                       CC11 CC16 CC21 CC22 CC23                       CC27 CC29 DD17 DD23 EE28                       EE43 FF25                 4L055 AG18 AG71 AG73 AG80 AH01                       AH33 DA22 DA40 GA09 GA16

Claims (1)

Claims: 1. A cationic resin-modified silica dispersion in which silica and a cationic resin are dispersed in a polar solvent,
A method for evaluating a cationic resin-modified silica dispersion, which comprises evaluating the cationic resin-modified silica dispersion by a cationic resin desorption ratio.