JP2967804B2 - Ultrafine fibrillated cellulose, method for producing the same, method for producing coated paper using ultrafine fibrillated cellulose, and method for producing dyed paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine fibrillated cellulose obtained by further reducing a fine fibrillated cellulose obtained by refining cellulose fibers to a predetermined degree, and a method for producing the same. Further, the present invention relates to a method for producing a coated paper and a method for producing a dyed paper utilizing the unique properties of the ultrafine fibrillated cellulose.

[0002]

2. Description of the Related Art When cellulose fibers such as wood pulp are miniaturized, division into fibrils, which are structural units forming a cell membrane, proceeds, so that micronization proceeds while branching while maintaining the fiber morphology. A fine fibrillated cellulose is obtained. It is known that adding such finely fibrillated cellulose to paper pulp to make paper yields paper having a number of interesting properties. For example, when fine fibrillated cellulose is added to a stock, an effect of increasing strength such as tensile strength and burst strength and an effect of increasing air permeability can be obtained. In addition, the microstructure also has the ability to retain fillers and improve dye adsorption.

It has been known that fine fibrillated cellulose can be obtained by applying a strong mechanical shearing force to cellulose fibers such as pulp for papermaking, and a number of production methods have been proposed. For example, Tokiko 60
In US Pat. No. 19921, a suspension of fibrous cellulose is passed through a small diameter orifice and added to the suspension at least three times.
Applying a high velocity with a pressure differential of 000 psi and then impinging on it to rapidly decelerate to effect a cutting action; and repeating this step to produce a substantially stable suspension of the cellulosic suspension. A method for producing microfibrous cellulose comprising the steps of:

JP-A-4-82907 proposes a method for producing fibrillated natural cellulose by crushing short fibers of natural cellulose fibers in a dry state. Further, JP-A-06-10286 discloses that a suspension of fibrous cellulose is wet-pulverized by a vibration mill pulverizer using beads or balls of a material such as glass, alumina, zirconia, zircon, steel and titania as a pulverizing medium. A method for producing fine fibrous cellulose is disclosed.

In the method proposed in JP-B-60-19921, it is necessary to pass a suspension of a fibrous substance such as pulp through a small-diameter orifice at a high pressure, and the solid content concentration is 1% by weight. When a higher suspension is passed through a small-diameter orifice, the orifice tends to be clogged. Therefore, the solid content of the suspension to be treated must be as low as 1% by weight or less. There is a problem. Also, in order to concentrate the suspension having a low solid content after the treatment to obtain a high concentration of fine fibrillated cellulose,
A great effort is required for the enrichment work. Such inefficiencies in processing efficiency and work efficiency are all reflected in the cost of the microfibrillated cellulose produced, so that the costly microfibrillated cellulose produced by such a method can be produced in a large amount as cheaply as paper. There is a problem that it cannot be used for products manufactured in Japan.

[0006] Further, in the method of pulverization in a dry state as proposed in the above-mentioned Japanese Patent Application Laid-Open No. 4-82907, unlike the pulverization by a wet method, since fibrillation of cellulose fibers does not occur so much, the water retention capacity is reduced. There is a problem that only small flake-like finely divided cellulose can be obtained.

Further, in the wet pulverization method using a vibration mill pulverizer proposed in Japanese Patent Application Laid-Open No. 06-10286, very long fibers such as softwood and non-wood fibers are very long. Time treatment is required, and even in the case of short fibers such as hardwoods, the prepared fine fibrillated cellulose has tackiness, so that it is difficult to separate it from beads or balls, which are grinding media, and processing efficiency is increased. There was a problem in the point.

A method for producing fine fibrillated cellulose which solves such problems has been proposed by the same applicant as the present invention in Japanese Patent Application No. 6-102755. This method uses an abrasive plate rubbing device in which a plurality of abrasive plates composed of abrasive grains having a grain size of 16 to 120 are rubbed and arranged, and the pulp slurry that has been beaten in advance is rubbed in the rubbing portion of this device. The number average fiber length of the fibers is 0.05 to 0.3 mm and the water retention value is 250
% Or more, 95% or more of the total number to the total number is 0.5
It is characterized by obtaining fine fibrillated cellulose having a size of not more than mm. According to this method, since the pulp slurry to be supplied to the abrasive plate rubbing device has been subjected to preliminary beating, even if the solid content concentration is set to a relatively high concentration of about 5 to 6% by weight, efficient refining treatment can be performed. There is an advantage that it can be performed.

[0009]

Along with the various production methods described above, various uses of fine fibrillated cellulose have been developed. Japanese Patent Application Laid-Open No. 4-194097 proposes a coated paper in which fine fibrillated cellulose is added to a paint for size press or the like, and this is coated on at least one side of paper. However, when the present inventors added fine fibrillated cellulose to a paint composed of starch and the like and applied it to paper to produce a coated paper, the paint thickened, and fine fibril There is a problem that the activated cellulose is agglomerated to some extent, it cannot be applied uniformly, and there is a feeling of foreign matter, which causes coating streaks and scratches, and further deteriorates the printability of coated paper. I understood. The present inventors have conducted intensive studies on the cause,
The fiber length distribution of the fine fibrillated cellulose is inappropriate,
We found that the cause was that the water retention value was too small.

[0010] The same applicant as the present application is disclosed in Japanese Patent Application No. Hei 6-118.
No. 833 proposes a method for producing a dyed paper in which a dye / pigment carrier in which fine fibrillated cellulose is loaded with a dye / pigment is added to a stock prepared mainly from papermaking pulp to make paper. Also in this method, it was found that if fine fibrillated cellulose of a certain size or more was contained, dyeing could not be performed uniformly, resulting in a state of very fine uneven dyeing.

Accordingly, an object of the present invention is to provide a fine fibrillated cellulose which is particularly suitable for being added to a paint used for producing coated paper, and further suitable as a dye / pigment carrier used for producing dyed paper. It was done as. Further, the present invention has been made for the purpose of providing a method capable of efficiently producing fine fibrillated cellulose suitable for the above uses.

[0012]

Means for Solving the Problems As a result of various studies to achieve the above object, the present inventors have further refined microfibrillated cellulose to a predetermined degree (in this specification, Is called “ultrafine fibrillated cellulose”), which is suitable for being added to paints for the production of coated paper and for use as a dye / pigment carrier for the production of dyed paper. It is a thing.

That is, the ultrafine fibrillated cellulose of the present invention has a number average fiber length of 0.05 to 0.1 mm, a water retention value of 350% or more, and an integrated number of 9 to the total number of fibers.
5% or more is 0.25 mm or less, and the fiber axis ratio is 50
The above is the feature.

The above ultrafine fibrillated cellulose is
Basically, the microfibrillated cellulose obtained by the method using the abrasive plate rubbing device proposed in the aforementioned Japanese Patent Application No. 6-102755 is manufactured by further ultrafine-refining using a high-pressure homogenizer. be able to.

That is, the method for producing ultra-fine fibrillated cellulose of the present invention comprises the steps of: By passing the pulp slurry that has been beaten in advance and pulverizing the pulp to obtain fine fibrillated cellulose, the resulting fine fibrillated cellulose is further subjected to ultrafine processing using a high-pressure homogenizer, whereby the number average fiber length is reduced. 0.05-0.1m
m, a water retention value of 350% or more, 95% or more of the total number of fibers with respect to the total number of fibers is 0.25 mm or less, and an ultrafine fibrillated cellulose having an axis ratio of fibers of 50 or more is obtained. It is.

The ultrafine fibrillated cellulose of the present invention has properties that are particularly suitable for being added to paints for the production of coated paper and for use as a dye / pigment carrier for the production of dyed paper. By using, a coated paper having excellent printability and a dyed paper without uneven dyeing can be produced as compared with the case where conventional fine fibrillated cellulose is used.

That is, the method for producing a coated paper of the present invention utilizing the properties of ultrafine fibrillated cellulose is characterized by applying a coating material to which ultrafine fibrillated cellulose is added to at least one side of the base paper. is there. Furthermore, the method for producing a dyed paper of the present invention utilizing the properties of ultrafine fibrillated cellulose is a method in which a dye / pigment carrier in which a dye / pigment is supported on ultrafine fibrillated cellulose is prepared using papermaking pulp as a main material. It is characterized in that papermaking is performed by adding it to the paper.

Many proposals have been made on a method for producing microfibrillated cellulose and its application, but a description of ultrafine fibrillated cellulose which has been further miniaturized to a predetermined degree as in the present invention, No proposal has been made for a specific manufacturing method and further for use.

Hereinafter, the method for producing the ultrafine fibrillated cellulose of the present invention will be described in detail. As described above, the step of producing fine fibrillated cellulose using the abrasive plate rubbing apparatus is the same as the method of producing fine fibrillated cellulose in Japanese Patent Application No. 6-102755. Even if an abrasive plate rubbing device is used, if the pulp slurry of long fibers that has not been beaten in advance is introduced into the abrasive plate rubbing device and the fineness treatment is performed, the water retention property of the fibers is reduced. Because it is bad, dehydration occurs first at the rubbed part of the abrasive plate,
The discharged fines are much thinner than the concentration of the introduced pulp slurry, resulting in poor treatment efficiency.
However, after the beating process is performed on the pulp slurry in advance, when the pulp slurry is introduced into the abrasive plate rubbing device and subjected to the refinement process, the refinement process can be performed while maintaining the solid concentration of the pulp slurry in a high state. At the same time, fine fibrillated cellulose having a high water retention value and a uniform fiber length distribution can be efficiently obtained in a relatively short time.

The degree of beating in the preliminary beating treatment can be classified into two types of beating degree depending on the type of pulp used as a raw material. One is a long fiber pulp having a number average fiber length of 0.8 mm or more.
After preliminarily beaten so as to be not more than 00 ml CSF, it is introduced into an abrasive plate rubbing device. Examples of such pulp include domestic spruce, spruce, pine, larch, etc. Includes fibers extracted by methods or chemical methods. In addition, pulp extracted from non-wood fibers is included. Typical non-wood fibers include cotton pulp, hemp, bagasse, kenaf, esparto, mulberry, mitsumata, ganpi, and the like. Regenerated cellulose such as rayon, tencel, and polynosic fiber is also included in the non-wood fiber.

The other type is a short fiber pulp having a number average fiber length of less than 0.8 mm. In this case, the pulp is pre-beaten so as to have a freeness of 600 ml CSF or less.
Examples of such pulp include domestic wood, linden, sen, poplar, hippo, etc., foreign-made aspen, cottonwood, black willow, yellow poplar, yellow birch, eucalyptus, etc. Includes fibers extracted by chemical methods.
In addition, some non-wood fibers include regenerated cellulose whose fiber length is shortened by a mechanical method.

The pulp that can be used as a raw material in producing the ultrafine fibrillated cellulose of the present invention is not limited in its production method, and pulp obtained by any method can be used. Pulp obtained by a mechanical method includes G
P, PGW, RGP, TMP, CTMP, SCP, CG
Pulp obtained by chemical methods such as P is KP, SP
Etc. can be used. In addition, pulp obtained by a special pulping method such as anthraquinone pulping, an alkapar method, an explosion method, a biomechanical pulping method, an organosolve pulping method, or a hydrotropic pulping method can be used.

In performing the pre-beating as a pretreatment, a general beater conventionally used for papermaking can be used. For example, any of beaters, jordans, conical refiners, single disc refiners, double disc refiners and the like can be used. Can be used.

Since the treatment efficiency of the pulp beating machine as described above is very high, it is preferable to minimize the freeness in the preliminary beating treatment using such a beating machine. In this case, it is preferable to set the freeness to 300 ml CSF or less.

FIGS. 1 and 2 schematically show an example of an abrasive plate rubbing apparatus used in the process for producing fine fibrillated cellulose of the present invention. The illustrated apparatus is configured by arranging an upper fixed abrasive plate 1 and a lower rotating abrasive plate 2 by rubbing, and the opposing inner surfaces of the two abrasive plates are tapered toward the center thereof. The flat surfaces 4a near the outer peripheral edges of the two abrasive plates are in contact with each other to form a rubbing portion 4. A hopper 6 is provided above the central opening 5 of the fixed abrasive plate 1.
The bottom communicates with the grinding chamber 3. The central opening of the rotary abrasive plate 2 is closed by a sealing plate 7, and the rotary abrasive plate 2 is rotated by a drive motor 9 via a shaft 8 extending downward from the lower surface thereof. An umbrella-shaped current plate 11 is disposed at substantially the center of the grinding chamber 3 by a support rod 10 extending upward from the sealing plate 7 of the rotary abrasive plate 2.

FIG. 3 is a view of the fixed abrasive plate 1 as viewed from the inner surface side. A feed groove 12 is formed in the tapered surface forming the grinding chamber 3 in a substantially radial direction from the central opening 5, and the rubbing portion is formed. The feed groove 12 is not formed on the flat surface 4a near the outer peripheral edge. In addition, the form and the number of the feed grooves are not necessarily limited to those illustrated.

The miniaturization processing by this apparatus is performed as follows. When the pulp slurry that has been beaten in advance is supplied to the hopper 6 (arrow A in FIG. 2), the pulp slurry flows down, is dispersed in the radial direction by the rectifying plate 11, and is uniformly supplied into the grinding chamber 3. . The pulp slurry in the grinding chamber 3 is sent to the rubbing portion 4 of the abrasive plates 1 and 2 by the centrifugal force generated by the rotation of the rotary abrasive plate 2 and the action of the feed groove 12 on the inner surface of the grinding chamber 3. The pulp is refined by the rubbing action of the upper and lower abrasive plates. The slurry of the fine fibrillated cellulose thus generated flows out of the outer peripheral edges of the abrasive plates 1 and 2 by centrifugal force (arrow B in FIG. 2). The slurry of the fine fibrillated cellulose flowing out is recirculated to the hopper 6 and can be subjected to a fine processing until a desired fine fibrillated cellulose is obtained.

The abrasive plate of the abrasive plate rubbing device is formed by solidifying abrasive particles, which are particles of an abrasive, with a binder,
As the material of the abrasive grains, those conventionally used, for example, diamonds, corundum, natural products such as emery,
Artificial products such as synthetic diamond, cubic boron nitride, alumina, silicon carbide, and boron carbide can be used. When using porous ceramics as the material of the abrasive grains, finely divided cellulose enters the pores of the ceramics,
Since there is a possibility that bacteria may be generated, it is desirable to fill the pores of the ceramic with a synthetic resin or the like in advance.

In particular, as the abrasive plate of the abrasive plate rubbing device used in the present invention, it is necessary to use an abrasive having a grain size of No. 16 to 120 which is a grain size specified in JIS R6001. is there. The inventors of the present invention have sequentially examined the abrasive grains having a grain size of No. 5 to No. 240 for the refinement effect of the pulp slurry. However, the desired fineness and uniformity do not progress, while, when the grain size is finer than # 120, clogging is likely to occur at the rubbing portion of the abrasive grain plate, and the refined pulp slurry is discharged. Turned out to be difficult. Therefore, the grain size of the abrasive grains is 16-120,
It is preferably number 24 to number 80.

The reason why the pulp is refined by rubbing the abrasive grain plate is that the fine abrasive grains constituting the abrasive grain plate form micro-projections on the rubbing surface of the abrasive grain plate, so that it is very uneven. It is greatly related to that. The pulp fiber receives a strong shearing force at the protruding portion of such abrasive grains, and the refinement proceeds.However, since the protruding portion exists everywhere on the rubbing surface of the abrasive grain plate, the cell wall of the pulp fiber is damaged. It will be efficiently divided into individual fibrils. Because of such a pulp fiber refining mechanism, any device having an abrasive plate rubbed and arranged can be used, and the device is not necessarily limited to the illustrated device. Further, as a method of supplying the pulp slurry to the abrasive plate rubbing section, various methods using a centrifugal force, gravity, a pressure feed pump, and the like can be adopted other than the structure shown in the drawing. Further, not only two abrasive plates but also an apparatus in which three or more abrasive plates are rubbed together can be used.

In the fine fibrillated cellulose production process of the present invention, the solid content of the pulp slurry supplied to the abrasive plate rubbing device also affects the fineness efficiency. If the solid content concentration is too high, the operating load of the abrasive plate rubbing device is excessively applied, making it difficult for the pulp to pass through the abrasive plate rubbing portion, and eventually the pulp is scorched by the heat generated at the rubbing portion. This is not preferable because it also causes a phenomenon in which it occurs. According to the present invention, the pulp slurry to be supplied to the abrasive plate rubbing device has been subjected to beating treatment in advance, so that passage of the pulp slurry through the rubbing portion is not hindered even when the solid content concentration is about 6% by weight. However, a solid concentration of about 4% by weight is optimal. In the conventional method for producing fine fibrillated cellulose using a high-pressure homogenizer that passes a pulp slurry through a small-diameter orifice, the solid concentration of the pulp slurry that can pass through the small-diameter orifice without clogging is about 1% by weight. In comparison with the above, it can be said that the solid content of the pulp slurry in the above-mentioned fine fibrillated cellulose production process of the present invention is considerably high, and as a result, an efficient micronization treatment can be performed.

In the present invention, the fine fibrillated cellulose thus obtained by the abrasive plate rubbing apparatus is further ultrafine-ized using a high-pressure homogenizer. Ultra-fine refining by a high-pressure homogenizer is performed by pumping a suspension of fine fibrillated cellulose under high pressure and passing it through a small-diameter orifice. Is achieved by giving A stable suspension of ultrafine fibrillated cellulose is obtained by repeating such ultrafine processing steps. In the ultra-fine processing step of the present invention, any apparatus can be used as long as it is based on the above principle. For example, an apparatus sold under the trade name of “Nanomizer” (manufactured by Nanomizer Co., Ltd.) or “Microfluidizer” (manufactured by Microfluidics Co., Ltd.) is an example.

FIG. 4 is a conceptual diagram showing an example of a high-pressure homogenizer used in the ultrafine processing step. Two disks including a front disk 21 and a rear disk 22 are sandwiched from the outside by cylindrical holding members 23 and 24 and are set in close contact with each other. FIG. 4 shows these disks and members separated from each other so that the inner surface of the front disk 21 and the inner surface of the rear disk 22 that are in close contact with each other when they are sandwiched can be seen. Each disc has two through holes 21a, 21
b, 22a and 22b are drilled, and grooves 21c and 22c connecting the two through holes are formed on the inner surface of each disk.
Is engraved. The width of the groove is smaller than the diameter of the through hole.
The two disks are set inward such that the two grooves 22c are shifted (cross-shaped) by 90 ° from each other.

The aqueous suspension of fine fibrillated cellulose obtained by the abrasive plate rubbing device is pressurized by a pump and is supplied with a raw material pressure of not less than several hundred kg / cm ² through a raw material pressure pipe (not shown). The high-pressure is sent to the high-pressure homogenizer at a high pressure, and reaches the outer surface of the front disk 21 through the cylindrical front-side suppressing member 23. Here, the raw material is divided into two by the two through holes 21a and 21b of the front disk, accelerated, and after passing through the disk 21, the orifice formed by the groove 21c and the flat inner surface of the rear disk 22 is simultaneously moved to the center. It is further accelerated and flows toward the surface, and collides with each other at the center to be ultrafine. Then this flow is 9
The orifices formed by the groove 22c of the disk 22 and the flat inner surface of the front disk 21 which are set at 0 ° are separated into two parts by flowing through the orifices.
a and 22b, and is discharged from the cylindrical rear-side restraining member 24 as an ultrafine fibrillated cellulose suspension.

The degree of ultrafine refining of the microfibrillated cellulose and homogenization of the suspension by the high-pressure homogenizer depends on the pressure of the high-pressure homogenizer and the number of times of passing through the high-pressure homogenizer. Pumping pressure is 500-20
Although it is suitable for the ultra-fine processing to be performed in the range of 00 kg / cm ² , 1000 to 2000 kg / cm ² is considered in view of productivity.
cm ² is more preferred.

The pulp pre-beating process by the beating device as described above, the fine fibrillated cellulose production process by the abrasive plate rubbing device, and the ultra-fine refining process by the high-pressure homogenizer are performed in this order, whereby the number average fiber length is obtained. Is 0.05-0.1mm, water retention value is 350%
As described above, 95% or more of the total number of fibers with respect to the total number of fibers is 0.25 mm or less, and the ultrafine fibrillated cellulose of the present invention having an axis ratio of fibers of 50 or more can be produced.
These steps may be performed continuously, or each step may be performed independently.

In the case where ultrafine fibrillated cellulose is to be produced directly using only a high-pressure homogenizer without using an abrasive plate rubbing apparatus, the solid content concentration of the raw pulp slurry to be pumped to the high-pressure homogenizer is adjusted. In order to prevent clogging of the orifice, the concentration must be as low as 1% by weight or less, and the number of times of passing through a high-pressure homogenizer must be increased to 10 or more. It becomes impossible to use it for the use as a chemical to be added to water.

The number average fiber length specified in the present invention is K
A value obtained by integrating the total lengths of the fibers present in a certain pulp suspension from data measured by a fiber length distribution measuring device (FS-200) manufactured by AJAANI (Finland) and dividing by the number of the fibers. The ratio of the total number is also obtained from the same measuring device. LBK, a raw material for ordinary paper
P, NBKP, etc. are each 0.5 mm in number average fiber length,
It has a length of about 1 mm, and the number average fiber length is at least 0.1 even for fibrillated fibers generated by beating.
The length is about 35 mm. In addition, the fine fibrillated cellulose produced using the abrasive plate rubbing device has a number average fiber length of 0.05 to 0.3 mm, and 95% or more of the total number of the total number is 0.5 mm or less. On the other hand, the ultrafine fibrillated cellulose produced by the present invention has a number average fiber length of 0.05 to 0.1 mm, and 95% or more of the total number of the total number is 0.25 mm or less,
It is further miniaturized.

The water retention value is an index of the degree of swelling of the pulp, and distinguishes the water taken in and held in the swollen fibers from the free water existing in the fibers and between the fibers by an appropriate centrifugal force. It is a value measured based on the idea that The water retention value specified in the present invention is also a value measured by the method specified in JAPAN TAPPI No. 26 based on the same concept, and a predetermined amount of a sample mat is formed in a predetermined filter in advance and centrifuged. It shows the value when the amount of retained water is divided by the amount of absolutely dry pulp after dewatering for 15 minutes at a centrifugal force of 3000 G using a separator. Normal unbeaten pulp shows only about 90%, and beaten pulp shows only about 200%. The water retention value of the fine fibrillated cellulose produced using the abrasive plate rubbing device is 250% or more. On the other hand, the water retention value of the ultrafine fibrillated cellulose produced in the present invention is 350% or more, and has a higher lower limit.

The measurement of the fiber axial ratio (fiber length / width) is as follows:
It was performed from direct observation with an optical microscope and an electron microscope. The ultrafine fibrillated cellulose produced in the present invention has a fiber width of 1 μm or less and the shortest fiber is about 50 μm, so the smallest axial ratio is 50, that is, the axial ratio is 50.
That is all. The ultrafine fibrillated cellulose of the present invention having such an axial ratio can be clearly distinguished from a powdery cellulose having a short axial ratio.

Next, a method for producing a coated paper utilizing the properties of the ultrafine fibrillated cellulose of the present invention will be described.
The ultrafine fibrillated cellulose of the present invention may be added to a coating applied by a size press device, a gate roll coating device, a bill blade coating device, or the like in an on-machine, that is, a drying zone of a paper machine, or may be applied to an off-machine coating device. By adding the paint to the coating material for coating, the coating property of the coating material can be improved, and various physical properties, particularly printability, of the coated paper obtained by coating this coating material on one or both sides of the base paper can be improved.

Examples of application to on-machine paints 1) Addition to surface size paints: styrene resin, styrene / acrylic resin, styrene / maleic resin, alkyl ketene dimer, starch, oxidized starch, hydroxyethylated starch Ultrafine fibrillated cellulose is usually added in an amount of 0.1 to 10% by weight to a known coating such as carboxymethylated cellulose, carboxymethylated guar gum, phosphorylated guar gum, oxidized guar gum, polyvinyl alcohol, acrylamide and the like. 2) Addition to lightweight coated paper coating: Ultrafine fibrillated cellulose is usually added to a well-known coating mainly containing a filler such as clay, calcium carbonate and kaolin and a binder.
Add 1 to 10% by weight and apply.

Example of application to off-machine paints Addition to coated paper or art paper paints: Ultrafine fibrillated cellulose is usually added to well-known paints containing fillers such as clay, calcium carbonate, kaolin and the like as binders. Add 0.1 to 10% by weight and apply.

The addition of ultrafine fibrillated cellulose to these coatings can improve the coating properties of the coatings and improve the physical properties of the coated papers, especially printability, for the following reasons. It seems to be due to. That is, the ultrafine fibrillated cellulose of the present invention has a water retention value of 35.
It has a water retention of 0% or more, has good water retention, and has thixotropic properties, so that the coating properties of the paint can be improved. In addition, since 95% or more of the total number of the ultrafine fibrillated cellulose is 0.25 mm or less with respect to the total number of the ultrafine fibrillated cellulose, a uniform coated surface can be obtained without a feeling of foreign matter. To improve printability, especially ink absorbency.

Further, the properties of the ultrafine fibrillated cellulose of the present invention can be used for producing dyed paper. As a method for producing this dyed paper, the present inventors have disclosed Japanese Patent Application No. 6-1.
The method proposed in US Patent No. 18833 can be used as it is. That is, a dye / pigment carrier in which a dye / pigment is supported on ultrafine fibrillated cellulose may be added to the papermaking pulp stock, mixed and paper-made, and dyeing is performed by adsorption of the dye / pigment carrier onto the papermaking pulp. Will be.

The amount of the dye / pigment carrier to be added to the paper stock is not particularly limited and may be appropriately adjusted depending on the density of dyeing required for the obtained dyed paper. It is preferable to add a dye / pigment carrier in the range of 0.01 to 10% by weight based on the weight of the dye / pigment carrier. In order to prepare the dye / pigment carrier by supporting the dye / pigment on the ultrafine fibrillated cellulose, usually, an aqueous solution or water solution of the dye / pigment is added to an aqueous suspension containing about 0.5 to 6% by weight of the ultrafine fibrillated cellulose. Add the suspension and stir evenly. As the dye / pigment, a dye / pigment conventionally used in the production of dyed paper can be used similarly. Examples of the dye include a basic dye, an acid dye, a direct dye, a fluorescent dye, a disperse dye, and a reactive dye. There is no limitation on the kind of the pigment, and inorganic pigments containing a metal oxide or sulfide as a main component and organic pigments obtained by adding a precipitant to a dissolved dye, which is generally referred to as a lake, to make it insoluble can be used widely. .

Since ordinary fine fibrillated cellulose tends to be dyed more intensely than pulp that has not been beaten, if a dye-pigment carrier composed of fine fibrillated cellulose has a fiber length of a certain length or more, it will be lost. When it is made into paper, it becomes visible and causes uneven dyeing. On the other hand, the dye / pigment carrier comprising the ultrafine fibrillated cellulose of the present invention is so fine that it cannot be visually confirmed, and therefore cannot be judged as uneven dyeing. Further, the dispersibility of the dye / pigment carrier is also important, and even if the primary fiber is fine, if secondary aggregation occurs, it will eventually look like a large fiber. As a result of the present inventors' examination of this point, the number average fiber length of the ultrafine fibrillated cellulose is 0.05 to 50 in order that the dye / pigment carrier cannot be completely judged by eyes.
It was confirmed that it was necessary that 0.1 mm and 95% or more of the total number of fibers with respect to the total number of fibers were 0.25 mm or less. Further, the water retention value of the fine fibrillated cellulose is greatly related to the dispersibility of the dye / pigment carrier. The ultrafine fibrillated cellulose of the present invention has a sufficiently high water retention value of 350% or more, so that the dye / pigment carrier is unlikely to settle and agglomerate, and has an excellent effect of forming a formation uniformly on a wire of a paper machine.

Further, in order for the dye / pigment carrier to be held in the paper, it is important that the dye / pigment carrier is fibrous, and the axial ratio needs to be 50 or more. By using the ultrafine fibrillated cellulose of the present invention satisfying such conditions for dyed paper, the yield of dyes and pigments can be increased and dyeing can be performed uniformly. The yield of the dye / pigment is related to the dye / pigment adsorption ability of the ultrafine fibrillated cellulose, and the water retention value of the ultrafine fibrillated cellulose is 350%.
The present inventors have also confirmed that dyeing and pigment adsorbability is significantly improved by the above.

[0049]

The present invention will be specifically described below with reference to examples and comparative examples. Parts and% shown in Examples and Comparative Examples
Indicates absolute dry weight parts and absolute dry weight%, both of which are based on absolute dry weight.

Example 1 NBKP was used as a raw material and beaten to 300 ml CSF in advance with a beater to prepare a pulp slurry having a solid content of 5%. This is shown in Fig. 1 to Fig. 3 by an abrasive plate rubbing device (trade name "Super Grindel" manufactured by Masuko Sangyo Co., Ltd. Abrasive particle size: No. 46. Number of rotation of rotary abrasive plate: 1800 rpm Abrasive grain clearance: 20 μm.
(Hopper capacity: 30 liters). The treated pulp slurry discharged from the rubbing portion of the abrasive plate was continuously recirculated to the hopper, and a fine fibrillated cellulose was obtained by setting a total of 30 minutes for the fine processing time. Next, after adjusting the solid content concentration of the aqueous suspension of fine fibrillated cellulose to 3%, the solid content was adjusted to 2% as shown in FIG.
Pressure sent to a high-pressure homogenizer equipped with two disks (trade name "Nanomizer", manufactured by Nanomizer Co., Ltd.)
Ultrafine fibrillated cellulose was obtained by repeating 5 times the process of pumping at 500 kg / cm ² to ultrafine. Table 1 shows the results of evaluating the properties of the obtained ultrafine fibrillated cellulose.

Example 2 An ultrafine fibrillated cellulose was obtained in the same procedure as in Example 1 except that LBKP was used as a raw material. Table 1 shows the results of evaluating the properties of the obtained ultrafine fibrillated cellulose.

Comparative Example 1 Table 1 shows the results of evaluating the properties of the fine fibrillated cellulose obtained by the pre-beating treatment using the beater and the fine treatment using the abrasive plate rubbing device in Example 1.
Shown in

Comparative Example 2 Table 1 shows the results of evaluating the properties of the fine fibrillated cellulose obtained by the pre-beating treatment using the beater and the fine treatment using the abrasive plate rubbing device in Example 2.
Shown in

Comparative Example 3 Table 1 shows the results of evaluation of the characteristics of commercially available fine fibrillated cellulose (trade name "Selish KY-100S", manufactured by Daicel Chemical Industries, Ltd.).

Comparative Example 4 Table 1 shows the results of evaluating the characteristics of commercially available fine powdered cellulose (trade name: "Ceolas Cream", manufactured by Asahi Kasei Kogyo Co., Ltd.).

[0056]

From Examples 1 and 2 in Table 1, the number average fiber length was 0.05 to 0.1 mm and the water retention value was 350 by using two devices, a grinding plate rubbing device and a high-pressure homogenizer, in this order. % Or more, 95% or more of the total number of fibers with respect to the total number of fibers is 0.25 mm or less, and the fiber axial ratio is 5% or less.
It can be seen that ultrafine fibrillated cellulose having a value of 0 or more can be efficiently produced. Further, fine fibrillated cellulose obtained using only an abrasive plate rubbing device as in Comparative Examples 1 and 2, furthermore, commercially available fine fibrillated cellulose of Comparative Example 3 and commercially available fine powdered cellulose of Comparative Example 4 were However, it is not possible to provide all of the properties of the above ultrafine fibrillated cellulose.

Example 3 A red direct dye (CI Direct) was added to the aqueous suspension of the ultrafine fibrillated cellulose obtained in Example 1.
20% of Red 23) was added to and mixed with the ultrafine fibrillated cellulose to prepare a red dye carrier carrying a dye. Unbeaten LB as pulp for papermaking
For 95 parts of solid content of stock prepared using KP,
5 parts of the dye carrier prepared above and 4 parts of aluminum sulfate were added to obtain 60 g / m ² of dyed paper by a usual hand-making method.

Example 4 A dyed paper was obtained in the same procedure as in Example 3, except that the ultrafine fibrillated cellulose obtained in Example 2 was used.

Comparative Example 5 A dyed paper was obtained in the same manner as in Example 3, except that the microfibrillated cellulose obtained in Comparative Example 1 was used instead of the ultrafine fibrillated cellulose.

Comparative Example 6 A dyed paper was obtained in the same procedure as in Example 3 except that the microfibrillated cellulose obtained in Comparative Example 2 was used instead of the ultrafine fibrillated cellulose.

Comparative Example 7 A dyed paper was obtained in the same procedure as in Example 3, except that a commercially available fine fibrillated cellulose “Serish KY-100S” was used instead of the ultrafine fibrillated cellulose.

Comparative Example 8 A dyed paper was obtained in the same procedure as in Example 3, except that a commercially available micronized cellulose "CEOLUS CREAM" was used instead of the ultrafine fibrillated cellulose.

Table 2 shows the results of evaluating the dyeability, dye yield and degree of uneven dyeing of the dyed papers obtained in Examples 3 and 4 and Comparative Examples 5 to 8 by the following methods. Dyeing property: L *, a specified in JIS Z 8130
*, B *. Because it uses a red dye,
As L * becomes smaller and a * becomes larger, the color becomes darker. Dye yield (%): Measure the absorbance of the dewatered waste liquid during papermaking, convert it into a concentration from a calibration curve prepared in advance, and calculate 100− (dye concentration of dewatered waste liquid) / (added dye concentration) × 100. Asked from. -Degree of uneven dyeing: Evaluated visually.

[0065]

As can be seen from Table 2, it can be confirmed that the dyed paper using the dye / pigment carrier made of the ultrafine fibrillated cellulose of the present invention has a high dye yield and the color of the sheet formed becomes dark. Furthermore, it was found that uneven dyeing, which is the biggest problem in dyeing, could be eliminated, and that the dye / pigment carrier could not be visually confirmed by setting the size to about the size of the ultrafine fibrillated cellulose of the present invention.

Example 5 0.3 part of sodium hexametaphosphate was added as a dispersant to 90 parts of clay and 10 parts of calcium carbonate, and the mixture was uniformly dispersed with an impeller at a solid content of 50%. 5 parts and 12 parts of SB latex were added, and 3 parts of the ultrafine fibrillated cellulose obtained in Example 1 was further added to obtain a paint having a solid content of 35%. The paint is weighed 80 g / m with a # 12 wire bar.
The base paper of No. ² was coated to obtain a coated paper for printing.

Example 6 A coated paper for printing was obtained in the same procedure as in Example 5, except that the ultrafine fibrillated cellulose obtained in Example 2 was used.

Comparative Example 9 A coated paper for printing was obtained in the same procedure as in Example 5, except that no ultrafine fibrillated cellulose was added.

Comparative Example 10 A coated paper for printing was obtained in the same procedure as in Example 5, except that a commercially available micronized cellulose "CEOLUS CREAM" was used instead of the ultrafine fibrillated cellulose.

The viscosities (cps, 20 ° C.) of the paints obtained in Examples 5 and 6 and Comparative Examples 9 and 10, streaking during coating, uniformity of the coated surface, smoothness of the coated surface, and printing Table 3 shows the results of evaluation of suitability (dry down, color development, dot gain). The evaluation of each characteristic was performed by the following methods. -Striping during coating: During coating, whether or not a streaking phenomenon occurs due to the presence of foreign matter or the like was visually evaluated. -Uniformity of coated surface: After coating, it was visually evaluated whether unevenness occurred on the coated surface due to uneven distribution of filler, binder, ultrafine fibrillated cellulose, and the like. -Smoothness of coated surface: The surface state after coating was evaluated by feeling.

Dry-down: Blue ink (trade name "TK High Plus Ai M"
Z ", manufactured by Toyo Ink Co., Ltd.) with an ink loading of 1.0 g, and the ink color density of the printed surface immediately after printing and 3
Macbeth densitometer (CRD-914)
Mold, manufactured by Macbeth). Evaluation was made according to the following criterion based on the amount of decrease in color density at this time. ◎ ：
0.10 or less, ：: 0.11 to 0.20, Δ: 0.21
-0.29, x: 0.30 or more.

Coloring property: A blue ink (trade name “TK High Plus Indigo MZ”) was printed with an ink filling amount of 1.0 g using an RI printing tester (manufactured by Akira Seisakusho Co., Ltd.), and the ink coloring density on the printed surface was measured. Three days later, Macbeth densitometer (CRD-914)
(Type). The color density at this time was evaluated according to the following criteria. ◎: 1.60 or more, ：: 1.50
1.59, Δ: 1.40 to 1.49, ×: less than 1.40.

Dot gain: One-color printing of black ink (trade name “Graf-G”, manufactured by Dainippon Ink Industries, Ltd.) using an offset printing machine (two-color machine, R202-OB type, manufactured by Roland) The halftone dot change rate of the portion having a dot area ratio of 40% was measured using a Macbeth densitometer (CRD-914 type), and evaluated according to the following criteria. ◎: within 2%, ：: 2
To 3.9%, Δ: 4 to 5.9%, ×: 6% or more.

[0075]

As shown in Table 3, when the ultrafine fibrillated cellulose of the present invention was added to a paint, the addition of 3 parts, which had an effect on printability, etc., gave an optimum value for the paint viscosity for coating. It was confirmed that streaking and smoothness during coating were improved by this. On the other hand, when a commercially available finely powdered micronized cellulose was added, the viscosity of the coating became too high, streaking at the time of coating, poor smoothness, and poor printability. In addition, the fine fibrillated cellulose of Comparative Examples 1, 2, and 3 was
In the case of adding a part, the number average fiber length was longer than that of the ultrafine fibrillated cellulose of the present invention. In addition, regarding the printability, when the ultrafine fibrillated cellulose was used, both the case where the ultrafine fibrillated cellulose was not used (Comparative Example 9) and the case where a commercially available product was used (Comparative Example 10) were compared. Then, it was confirmed that the dry-down, coloring, dot gain, and the like during printing were improved.

[0077]

As described above, the ultrafine fibrillated cellulose of the present invention has an advantage that when used in the production of dyed paper, the yield of the dye is improved and the dye can be dyed uniformly. Furthermore, when used as a coating paint used in the production of coated paper, the coating suitability is improved, and uniform and smooth coating is possible. Since the work layer is bulky, there is a remarkable effect that printability such as dry down, color development, and dot gain is improved.

Further, in producing the ultrafine fibrillated cellulose of the present invention, the fine fibrillated cellulose obtained by pulverizing preliminarily beaten pulp using an abrasive plate rubbing device is further used by using a high-pressure homogenizer. By the ultrafine treatment, the number average fiber length is 0.1.
A super-fine, uniform fiber length distribution with a water retention value of 350% or more, 95% or more of the total number of fibers with respect to the total number of fibers of 0.25 mm or less, and an axial ratio of fibers of 50 or more. Fine fibrillated cellulose can be efficiently produced in a high-concentration slurry state.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an abrasive plate rubbing apparatus used for producing the ultrafine fibrillated cellulose of the present invention.

FIG. 2 is a sectional view of the apparatus of FIG.

FIG. 3 is a plan view showing an example of an abrasive plate used in the apparatus of FIG.

FIG. 4 is a conceptual diagram showing an example of a high-pressure homogenizer used for producing the ultrafine fibrillated cellulose of the present invention.

[Explanation of symbols]

 1: fixed abrasive plate 2: rotating abrasive plate 3: grinding chamber 4: rubbing section 6: hopper 9: drive motor 12: feed groove 21: front disk 22: rear disk 21a, 21b, 22a, 22b: penetrating Holes 21c, 22c: grooves 23, 24: cylindrical holding member

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-109699 (JP, A) JP-A-57-77387 (JP, A) JP-A-4-289294 (JP, A) JP-A-5- 86598 (JP, A) JP-A-4-82907 (JP, A) JP-A-7-324300 (JP, A) JP-B-60-19921 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21D 1/30, 1/20 D21H 15/00 D21H 19/34 D21H 21/28

Claims (4)

(57) [Claims] (1) a number average fiber length of 0.05 to 0.1 mm;
An ultrafine fibrillated cellulose having a water retention value of 350% or more, 95% or more of the total number of fibers with respect to the total number of fibers of 0.25 mm or less, and a fiber axial ratio of 50 or more. 2. A pulp slurry, which has been beaten in advance, is passed through a rubbing unit of an abrasive plate rubbing apparatus in which a plurality of abrasive plates made of abrasive grains having a grain size of 16 to 120 are rubbed and arranged. By making the fine fibrillated cellulose by pulverizing, the resulting fine fibrillated cellulose is further subjected to ultrafine processing using a high-pressure homogenizer, so that the number average fiber length is 0.05 to 0.1 mm and the water retention value is 350. % Or more, 95% or more of the total number of fibers with respect to the total number of fibers is 0.25 mm or less, and the fiber axial ratio is 5% or less.
A method for producing ultrafine fibrillated cellulose, wherein an ultrafine fibrillated cellulose having a value of 0 or more is obtained. 3. A method for producing coated paper, comprising applying a coating material to which the ultrafine fibrillated cellulose according to claim 1 is added to at least one side of a base paper. 4. A papermaking method comprising adding a dye / pigment carrier in which a dye / pigment is supported on the ultrafine fibrillated cellulose according to claim 1 to a paper stock prepared mainly from papermaking pulp. Manufacturing method of dyed paper.