JP2024029630A - Scaffolding material for cell culture, manufacturing method thereof, method for producing cultured cell, method for producing sphere, and cell culture container - Google Patents

Abstract

To provide a scaffolding material for cell culture that has excellent transparency and can be used in scaffold-type cell culture, particularly a scaffolding material for cell culture that can form a scaffolding material with a hydrogel pattern using a simple method by exposure and development.SOLUTION: Provided is a scaffolding material for cell culture containing a fibrous cellulose with an average fiber width of 100 nm or less, and a negative radiation-sensitive component containing a polymerizable compound and a polymerization initiator, the content of the negative radiation-sensitive component being 20 to 200 pts.mass based on 100 pts.mass of the fibrous cellulose, the negative radiation-sensitive component being a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof.SELECTED DRAWING: None

Description

The present invention relates to a scaffold for cell culture, a method for producing the same, a method for producing cultured cells, a method for producing spheres, and a container for cell culture.

In cell culture technology, the cultivation of tissues having functions equivalent to in-vivo tissues is attracting attention.
As a cell culture technique, a patterned film is formed on a substrate using a radiation-sensitive resin composition, and this patterned film is used as a partition wall to form a region defined by a cell adhesion region and a cell non-adhesion region. However, methods for culturing cells in cell adhesion areas are well known. In this so-called micropattern type cell aggregate formation mode, which forms adhesive areas and non-adhesive areas for cells, plastic substrates are mainly used, and cells are attached to such substrates. However, there are issues such as the difficulty in transporting nutrients and gases to the bottom of the cell compared to the top of the cell. In addition, because cell adhesion to plastic substrates is relatively high, there are issues with the difference in the degree of freedom for cell growth in the vertical direction to the plastic substrate surface and the degree of freedom for cell growth in the horizontal direction to the plastic substrate surface. be.

In contrast, in scaffold-type cell culture methods that form cell aggregates while moderately suppressing cell adhesion, hydrogel substrates that are mechanically soft and have excellent permeability to nutrients and gases are used. There is. Since culture using the hydrogel substrate can reproduce a more natural cell environment than culture using the plastic substrate, the hydrogel substrate is considered to be ideal as a substrate for cell culture outside the body.

It is well known that hydrogels are formed from alginic acid-derived compounds and cellulose-derived compounds, but with increasing awareness of the use of renewable resources, compounds derived from plant materials such as cellulose nanofibers are being used. This is being considered.

For example, Patent Documents 1 to 3 describe culturing cells using a hydrogel (substrate) containing such cellulose nanofibers and the like.

Japanese Patent Application Publication No. 2018-102291 Special Publication No. 2015-530104 Special Publication No. 2020-524507

If cells can be cultured on a patterned hydrogel, cell growth and differentiation along the pattern can be promoted, and it is thought that it will be possible to create cell clusters and cell tissues with desired shapes. On the other hand, little is known about the technology for obtaining hydrogels in desired patterns. This is because the technology for forming a hydrogel pattern is limited, and there are still technical issues such as the time it takes to form a hydrogel pattern.

The present invention was made in view of the above, and provides a cell culture scaffold material that has excellent transparency and can be used for scaffold-type cell culture, particularly a scaffold material having a hydrogel pattern, which can be easily produced by exposure and development. An object of the present invention is to provide a scaffold material for cell culture that can be formed by a method that can be used in a cell culture.

The present inventors conducted extensive studies to solve the above problems. As a result, the inventors discovered that the above problem could be solved by the following configuration example, and completed the present invention.
A configuration example of the present invention is as follows.

[1] Fibrous cellulose with an average fiber width of 100 nm or less,
Contains a negative radiation-sensitive component containing a polymerizable compound and a polymerization initiator,
The content of the negative radiation-sensitive component is 20 to 200 parts by mass based on 100 parts by mass of the fibrous cellulose,
The negative radiation-sensitive component is a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof;
Scaffolding material for cell culture.

[2] The cell culture scaffold material according to [1], which has a hydrogel pattern obtained by exposing and developing the cell culture scaffold material.

[3] The cell culture scaffold material according to [1] or [2], wherein the polymerizable compound has at least one group selected from a (meth)acryloyloxy group and a (meth)acrylamide group.

[4] The cell culture scaffold material according to any one of [1] to [3], which has a haze of 10% or less.

[5] Irradiating a part of the cell culture scaffold material according to any one of [1] to [4] with radiation, and washing the unexposed part with at least one selected from water and a water-containing solvent. A method for producing a scaffold for cell culture, including the step of removing it to form a hydrogel pattern.

[6] A method for producing cultured cells, comprising the step of culturing cells on the scaffold for cell culture according to any one of [1] to [4].
[7] A method for producing spheres, comprising a step of culturing cells on the cell culture scaffold material according to any one of [1] to [4].

[8] A cell culture container comprising the cell culture scaffold material according to [2], wherein at least a portion of the cell culture area is provided with the hydrogel pattern.

According to the present invention, a cell culture scaffold material that has excellent transparency and can be used for scaffold-type cell culture, particularly a scaffold material having a hydrogel pattern (hereinafter also referred to as "patterned hydrogel scaffold material"), A hydrogel pattern can be formed by a simple method of exposure and development, specifically, by removing at least part of the exposed and unexposed areas formed by exposure by development. , can provide a scaffold material for cell culture.
According to the patterned hydrogel scaffold material, a scaffold suitable for cell culture can be provided, and cells can be selectively cultured in desired areas to form spheres (cell clusters). In addition, the patterned hydrogel scaffold material can be a patterned one-layer scaffold material rather than a laminate consisting of a hydrogel pattern and a support substrate, so that the hydrogel pattern and the support substrate can be patterned. There is no need to consider adhesion, etc.
Furthermore, according to the present invention, it is possible to provide a cell culture container with excellent cell cluster formation properties.

FIG. 1 is a graph showing the relationship between the amount of NaOH added dropwise to fibrous cellulose having phosphorus oxoacid groups and pH. FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to fibrous cellulose having a carboxy group and pH.

≪Scaffolding material for cell culture≫
The scaffold material for cell culture according to the present invention (hereinafter also referred to as "this scaffold material") is
Fibrous cellulose with an average fiber width of 100 nm or less,
Contains a negative radiation-sensitive component containing a polymerizable compound and a polymerization initiator,
The content of the negative radiation-sensitive component is 20 to 200 parts by mass based on 100 parts by mass of fibrous cellulose,
The negative radiation-sensitive component is a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof.

The scaffolding material containing fibrous cellulose has extremely high transparency and has an average fiber width of 100 nm or less, so it is possible to form a fine hydrogel pattern on the micron order.
When one embodiment of the present scaffolding material is exposed to light to form an exposed area and an unexposed area, the radiation-sensitive component in the exposed area is cured to form a cured area that is insoluble not only in water but also in organic solvents. . In addition, if the unexposed area is developed with water or a water-containing solvent (developer), at least a portion of the radiation-sensitive component can be removed, and the fibrous cellulose can be directly applied to the scaffold material (pattern area). It can remain and absorb water in the developer solution to form a hydrogel pattern (cellulose hydrogel pattern), that is, a patterned hydrogel scaffold can be obtained. At this time, by exposing the scaffolding material to light through a photomask, a patterned hydrogel scaffolding material having a pattern of a desired shape can be obtained.
When cells are seeded and cultured on the obtained patterned hydrogel scaffold, the gel pattern section functions as a scaffold, and the cells can gather in the gel pattern section to form a cell mass. In this case, a gel pattern can be formed according to the shape of the photomask, and cell clusters can be formed according to various gel pattern shapes, so it can be applied to cell culture vessels (including cell culture instruments and cell culture devices). can be expected.

The meanings of terms used in this specification are as follows.
A numerical range represented by "~" means a range (above and below) that includes the numerical values at both ends.
"(Meth)acrylic" is a general term for "acrylic" and "methacrylic", and individually means acrylic and methacrylic. The same applies to "(meth)acryloyl", "(meth)acryloyloxy", "(meth)acrylic acid", "(meth)acrylate" and "(meth)acrylamide".

<Fibrous cellulose>
This scaffolding material contains fibrous cellulose with an average fiber width of 100 nm or less.
Note that the fibrous cellulose is, for example, monofilament cellulose.
The fibrous cellulose used in this scaffolding material may be one type or two or more types (two or more types may be used with different shapes such as average fiber width, and two or more types with different materials such as functional groups). ). Further, fibrous cellulose containing an ionic group, which will be described later, and unmodified fibrous cellulose may be used in combination.

The average fiber width of the fibrous cellulose is preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and even more preferably 2 nm or more and 10 nm or less.
By having the average fiber width of the fibrous cellulose within the above range, this scaffolding material with excellent transparency can be easily obtained, and the cellulose molecules are prevented from dissolving in water and water-containing solvents, and the fibrous cellulose Effects such as improvements in strength, rigidity, and dimensional stability are more likely to be realized.
Note that the fiber width refers to the length in the direction perpendicular to the fiber length direction of fibrous cellulose, as observed in an electron micrograph or the like.

The average fiber width of fibrous cellulose can be measured, for example, using an electron microscope as follows.
First, an aqueous suspension of fibrous cellulose with a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast onto a hydrophilic carbon film-coated grid to provide a sample for TEM observation. shall be. If wide fibers are included, a SEM image of the surface cast on glass may be observed. Next, observation using an electron microscope is performed at a magnification of 1,000 times, 5,000 times, 10,000 times, or 50,000 times, depending on the width of the fiber to be observed. However, the sample, observation conditions, and magnification should be adjusted to satisfy the following conditions (1) and (2).
(1) Draw a straight line X at any location in the observed image, and 20 or more fibers intersect with the straight line X.
(2) Draw a straight line Y that intersects the straight line X perpendicularly within the same image, and 20 or more fibers intersect with the straight line Y.

For an observed image that satisfies the conditions (1) and (2) above, the widths of the fibers intersecting the straight line X and the widths of the fibers intersecting the straight line Y are visually read. In this way, at least three sets of observation images of surface portions that do not overlap with each other are obtained. Then, for each image, read the width of the fibers that intersect the straight line X and the fibers that intersect the straight line Y. In this way, the width of at least 20 x 2 x 3 = 120 fibers is read. Then, the average value of the read fiber widths is defined as the average fiber width of the fibrous cellulose.

The average fiber length of the fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1,000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and even more preferably 0.1 μm or more and 600 μm or less.
When the average fiber length is within the above range, destruction of the crystalline region of fibrous cellulose can be suppressed. Furthermore, when a dispersion of fibrous cellulose is used as a raw material for the present scaffolding material, it is easy to adjust the viscosity of the dispersion to an appropriate range.
The average fiber length of fibrous cellulose can be determined, for example, by image analysis using TEM, SEM, or AFM. Specifically, the average fiber length of the 120 fibers read in the same manner as the average fiber width is calculated. It can be determined by calculating the average.

The axial ratio (average fiber length/average fiber width) of the fibrous cellulose is not particularly limited, but is preferably 20 or more and 10,000 or less, more preferably 50 or more and 1,000 or less.
When long fiber fibrous cellulose with a large axial ratio is used, the viscosity of the fibrous cellulose dispersion tends to increase.
When the axial ratio is at least the lower limit, it is easy to form a scaffolding material containing fibrous cellulose, and when a fibrous cellulose dispersion is prepared, sufficient thickening properties are easily obtained. Further, it is preferable that the axial ratio is equal to or less than the upper limit value, for example, because handling such as dilution becomes easier when handling the fibrous cellulose as an aqueous dispersion.

It is preferable that the fibrous cellulose has a type I crystal structure. Here, the fact that fibrous cellulose has a type I crystal structure can be identified in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ=1.5418 Å) monochromated with graphite. Specifically, it can be identified because it has typical peaks at two positions: around 2θ=14° to 17° and around 2θ=22° to 23°.

The proportion of type I crystal structure in the fibrous cellulose is preferably 30% or more, more preferably 40% or more, and still more preferably 50% or more.
When the proportion of the type I crystal structure is within the above range, even better performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion.
The proportion of type I crystal structure is determined by measuring an X-ray diffraction profile and using the pattern in a conventional manner (eg, Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

The content of fibrous cellulose in the present scaffolding material is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably is 50% by mass or more, preferably 83.3% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less.

It is preferable that the fibrous cellulose has, for example, at least one kind selected from the group consisting of an ionic group and a nonionic group.
When the fibrous cellulose has an ionic group, the ionic group may be one type or two or more types. Moreover, when the fibrous cellulose has a nonionic group, the number of the nonionic groups may be one or two or more.
The fibrous cellulose may be subjected to a treatment for introducing an ionic group or a nonionic group, or may not be subjected to a treatment for introducing an ionic group or a nonionic group.
From the viewpoint of improving the dispersibility of the fibrous cellulose in the dispersion medium and increasing the fibrillation efficiency in the fibrillation treatment, it is more preferable that the fibrous cellulose has an ionic group.
Examples of the ionic group include one or both of an anionic group and a cationic group.
Further, examples of the nonionic group include an alkyl group and an acyl group.

Examples of the cationic group include an ammonium group, a phosphonium group, and a sulfonium group. Among these, an ammonium group is preferred.

In one embodiment of the present invention, it is particularly preferable to have an anionic group as the ionic group.

Examples of the anionic group include a phosphorus oxo acid group or a substituent derived from a phosphorus oxo acid group (hereinafter also simply referred to as a "phosphorus oxo acid group"), a carboxy group or a substituent derived from a carboxy group (hereinafter simply referred to as a "carboxy group"). ), a sulfur oxo acid group or a substituent derived from a sulfur oxo acid group (hereinafter also simply referred to as a ``sulfur oxo acid group''), a xanthate group or a substituent derived from a xanthate group (hereinafter simply referred to as a ``xanthate group'') ), a phosphonic group or a substituent derived from a phosphonic group (hereinafter also simply referred to as a "phosphonic group"), a phosphine group or a substituent derived from a phosphine group (hereinafter also simply referred to as a "phosphine group"), Examples include a sulfone group or a substituent derived from a sulfone group (hereinafter also simply referred to as "sulfone group"), a carboxyalkyl group, or a substituent derived from a carboxyalkyl group. Among these, from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a sulfur oxo acid group, a substituent derived from a sulfur oxo acid group, a carboxymethyl group, a carboxyethyl group, and a sulfone group. At least one selected from the group consisting of a phosphorus oxo acid group, a substituent derived from a phosphorus oxo acid group, a carboxy group, a sulfur oxo acid group, and a substituent derived from a sulfur oxo acid group One kind is more preferable, and a phosphorus oxo acid group is particularly preferable.
By introducing a phosphorus oxoacid group as an anionic group, the dispersibility of fibrous cellulose can be further improved even under alkaline or acidic conditions, resulting in a scaffold material with high strength and high transparency. become more susceptible to

The phosphorus oxo acid group or the substituent derived from the phosphorus oxo acid group is, for example, a group represented by the following formula (1).
A plurality of groups represented by the following formula (1) may be introduced into each fibrous cellulose. In this case, a plurality of groups represented by the following formula (1) introduced may be the same or different.

In formula (1), a, b, and n are natural numbers, and m is an arbitrary number (a=b×m). At least one of n α and α' is O 2 ⁻ , and the rest are R or OR. Note that all of each α and α' may be O ^{2 −} . The n α's may all be the same or may be different. β ^b+ is a monovalent or higher cation consisting of an organic or inorganic substance.
Note that in formula (1), n is preferably 1.

R is independently a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group A hydrocarbon group, an unsaturated cyclic hydrocarbon group, an aromatic group, or a group derived from these.
In addition, when multiple R's exist in formula (1) or when multiple types of substituents represented by the above formula (1) are introduced into the fibrous cellulose, each of the multiple R's is the same. It may be different or different.

Examples of the saturated linear hydrocarbon group include methyl group, ethyl group, n-propyl group, and n-butyl group.
Examples of the saturated-branched hydrocarbon group include i-propyl group and t-butyl group.
Examples of the saturated cyclic hydrocarbon group include a cyclopentyl group and a cyclohexyl group.
Examples of the unsaturated linear hydrocarbon group include a vinyl group and an allyl group.
Examples of the unsaturated branched hydrocarbon group include i-propenyl group, 2-butenyl group, and 3-butenyl group.
Examples of the unsaturated cyclic hydrocarbon group include a cyclopentenyl group and a cyclohexenyl group.
Examples of the aromatic group include a phenyl group and a naphthyl group.

Further, the derivative group for R is selected from functional groups such as a carboxy group, a carboxylate group (-COO ^- ), a hydroxy group, an amino group, and an ammonium group on the main chain or side chain of the various hydrocarbon groups. Examples include, but are not particularly limited to, functional groups to which at least one type of functional group is added or substituted.

The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, more preferably 10 or less.
By having the number of carbon atoms constituting the main chain of R within the above range, the molecular weight of the phosphorus oxo acid group can be set in an appropriate range, and the fiber raw material before introducing the phosphorus oxo acid group (fiber raw material containing cellulose described below) It is also possible to increase the yield of fine cellulose fibers into which phosphorus oxo acid groups have been introduced.

β ^b+ is a monovalent or higher cation consisting of an organic or inorganic substance.
In addition, when multiple β ^b+ exist in formula (1) or when multiple types of substituents represented by the above formula (1) are introduced into the fibrous cellulose, each of the multiple β ^b+ exists They may be the same or different.

Examples of monovalent or higher valent cations made of organic matter include organic onium ions.
Examples of organic onium ions include organic ammonium ions and organic phosphonium ions. Examples of organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions.
Examples of monovalent or higher valent cations made of inorganic substances include ions of alkali metals such as sodium, potassium, and lithium, ions of divalent metals such as calcium and magnesium, hydrogen ions, and ammonium ions.
Monovalent or higher cations made of organic or inorganic substances are not particularly limited, but include sodium, which does not easily yellow when heating fiber raw materials containing β ^b+ (fiber raw materials containing cellulose below) and is easy to use industrially. Or potassium ion is preferred.

More specifically, the phosphorus oxo acid group or the substituent derived from the phosphorus oxo acid group includes a phosphoric acid group (-PO ₃ H ₂ ), a salt of a phosphoric acid group, a phosphorous acid group (-PO ₂ H ₂ ), and salts of phosphorous acid groups. In addition, phosphorus oxo acid groups or substituents derived from phosphorus oxo acid groups include groups with phosphoric acid groups (e.g., pyrophosphoric acid groups), groups with phosphonic acids (e.g., polyphosphonic acid groups), phosphoric acid ester groups ( Examples: monomethyl phosphate group, polyoxyethylene alkyl phosphate group), alkylphosphonic acid group (eg, methylphosphonic acid group), etc. may be used.

The sulfur oxo acid group or the substituent derived from the sulfur oxo acid group is, for example, a group represented by the following formula (2).
A plurality of types of groups represented by the following formula (2) may be introduced into each fibrous cellulose. In this case, a plurality of groups represented by the following formula (2) introduced may be the same or different.

In formula (2), b and n are natural numbers, p is 0 or 1, and m is an arbitrary number (1=b×m). Note that when n is 2 or more, the plural p's may be the same number or may be different numbers.

β ^b+ in formula (2) is a monovalent or higher cation consisting of an organic substance or an inorganic substance.
In addition, when multiple types of substituents represented by the above formula (2) are introduced into fibrous cellulose, the multiple β ^b+s may be the same or different.

Examples of monovalent or higher cations made of organic matter include organic onium ions.
Examples of organic onium ions include organic ammonium ions and organic phosphonium ions. Examples of organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions.
Examples of monovalent or higher valent cations made of inorganic substances include ions of alkali metals such as sodium, potassium, and lithium, ions of divalent metals such as calcium and magnesium, hydrogen ions, and ammonium ions.
Monovalent or higher cations made of organic or inorganic substances are not particularly limited, but include sodium that does not easily yellow when heating fiber raw materials containing β ^b+ (fiber raw materials containing cellulose below) and is easy to use industrially. Or potassium ion is preferred.

The amount of ionic groups introduced into the fibrous cellulose is preferably 0.10 mmol/g or more, more preferably 0.20 mmol/g or more, even more preferably 0.50 mmol/g or more, per 1 g (mass) of fibrous cellulose. Particularly preferably, it is 1.00 mmol/g or more.
The amount of ionic groups introduced into the fibrous cellulose is preferably 5.20 mmol/g or less, more preferably 3.65 mmol/g or less, and even more preferably 3.50 mmol/g per 1 g (mass) of fibrous cellulose. It is particularly preferably 3.00 mmol/g or less.
When the amount of ionic groups introduced is within the above range, the fibrous cellulose can be easily refined and the stability of the fibrous cellulose can be improved. Furthermore, by introducing the amount of ionic groups within the above range, the fibrous cellulose can exhibit various favorable properties such as thickening properties.
Here, the denominator in the unit mmol/g indicates the mass of the fibrous cellulose when the counter ion (β ^b+ ) is a hydrogen ion (H ⁺ ).

The amount of ionic groups introduced into fibrous cellulose can be measured, for example, by neutralization titration. In the measurement using the neutralization titration method, the amount introduced is measured by adding an alkali such as an aqueous sodium hydroxide solution to the slurry containing the obtained fibrous cellulose and determining the change in pH.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped and pH for a fibrous cellulose-containing slurry having phosphorus oxoacid groups. The amount of phosphorus oxoacid groups introduced into fibrous cellulose is measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. Note that, if necessary, a defibration process similar to the defibration process described below may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, while adding an aqueous sodium hydroxide solution to the slurry treated with the ion exchange resin, changes in pH are observed, and a titration curve as shown in the upper part of FIG. 1 is obtained.

The titration curve shown in the upper part of Figure 1 plots the pH when an aqueous sodium hydroxide solution is added, and the titration curve shown in the lower part of Figure 1 plots the pH when the aqueous sodium hydroxide solution is added. The increment (differential value) (1/mmol) of pH is plotted. In this neutralization titration, two points at which the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum are confirmed on a curve in which the measured pH is plotted against the amount of alkali added. Among these, the maximum point of increment obtained first after starting to add the alkali is called the first end point, and the maximum point of increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid of fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the first end point to the second end point is equal to the amount of alkali required from the first end point to the second end point. The amount is equal to the amount of second dissociated acid in the fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the start of titration to the second end point is the amount of fibrous cellulose contained in the slurry used for titration. is equal to the total amount of dissociated acids. Then, the value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated becomes the amount of phosphorus oxo acid group introduced (mmol/g) (However, When the counter ion (β ^b+ ) is a hydrogen ion (H ⁺ ). Note that simply the amount of phosphorus oxo acid groups introduced (or the amount of phosphorus oxo acid groups) refers to the amount of the first dissociated acid.

In FIG. 1, the region from the start of titration to the first end point is called the first region, and the region from the first end point to the second end point is called the second region.
For example, when the phosphorus oxo acid group is a phosphoric acid group and this phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphorus oxo acid group (also referred to herein as "second dissociated acid amount") appears. ) decreases, and the amount of alkali required in the second region is smaller than the amount of alkali required in the first region. On the other hand, the amount of strong acid groups in the phosphorus oxo acid group (also referred to herein as "first dissociated acid amount") matches the amount of phosphorus atoms regardless of the presence or absence of condensation. In addition, when the phosphorus oxo acid group is a phosphorous acid group, there is no weakly acidic group in the phosphorus oxo acid group, so the amount of alkali required for the second region is reduced, or the amount of alkali required for the second region is reduced. may be zero. In this case, in the titration curve, there is one point where the pH increment becomes maximum.

Note that the above-mentioned amount of phosphorus oxo acid groups introduced (mmol/g) has a denominator indicating the mass of acid type fibrous cellulose. (Also referred to as "acid type"). On the other hand, if the counter ion of the phosphorus oxo acid group is substituted with any cation C so as to have a charge equivalent, convert the denominator to the mass of the fibrous cellulose when the cation C is the counter ion. Thus, the amount of phosphorus oxo acid groups (hereinafter also referred to as "phosphorus oxo acid group amount (C type)") (mmol/g) possessed by the fibrous cellulose in which cation C is the counter ion can be determined.

The amount of phosphorus oxo acid groups (C type) is calculated using the following formula.
Amount of phosphorus oxo acid groups (C type) = Amount of phosphorus oxo acid groups (acid type)/{1+(W-1)×A/1000}
A [mmol/g]: Total amount of anions derived from phosphorus oxo acid groups possessed by fibrous cellulose (value that is the sum of the first dissociated acid amount and the second dissociated acid amount of the phosphorus oxo acid groups)
W: formula weight per valence of cation C (e.g. 23 for Na, 9 for Al)

FIG. 2 is a graph showing the relationship between the amount of NaOH added dropwise to fibrous cellulose having a carboxy group and pH.
The amount of carboxy groups introduced into fibrous cellulose is measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. Note that, if necessary, a defibration process similar to the defibration process described below may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, while adding an aqueous sodium hydroxide solution to the slurry treated with the ion exchange resin, changes in pH are observed, and a titration curve as shown in FIG. 2 is obtained. Note that, if necessary, a defibration process similar to the defibration process described below may be performed on the measurement target.

As shown in Figure 2, in this neutralization titration, in the curve plotting the measured pH against the amount of alkali added, there is one point where the increment (differential value of pH with respect to the amount of alkali added) is maximum. Observed. The maximum point of this increment is called the first end point, and the region from the start of titration to the first end point is called the first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the slurry used for titration. Then, the value obtained by dividing the amount of alkali (mmol) required in the first region of the titration curve by the solid content (g) in the fibrous cellulose-containing slurry to be titrated is the amount of carboxy group introduced (mmol). /g).

The above-mentioned amount of carboxy groups introduced (mmol/g) is the amount of substituents per 1 g of mass of fibrous cellulose when the counter ion of the carboxy group is a hydrogen ion (H ⁺ ) (hereinafter referred to as "amount of carboxy groups (acid)"). type).
On the other hand, if the counter ion of a carboxy group is substituted with an arbitrary cation C such that the counter ion becomes charge equivalent, that is, if it is a substituent derived from a carboxy group, the denominator should be changed so that the cation C is the counter ion. By converting to the mass of fibrous cellulose at a certain time, the amount of carboxy groups possessed by fibrous cellulose whose counter ion is cation C (hereinafter also referred to as "carboxy group amount (C type)") (mmol/g) can be found.

The amount of carboxy groups (C type) is calculated using the following formula.
Carboxy group weight (C type) = Carboxy group weight (acid type)/{1+(W-1)×(carboxy group weight (acid type))/1000}
W: formula weight per valence of cation C (e.g. 23 for Na, 9 for Al)

In addition, the amount of sulfur oxoacid groups introduced into fibrous cellulose can be determined by wet ashing the obtained fibrous cellulose using perchloric acid and concentrated nitric acid, diluting it at an appropriate ratio, and determining the amount of sulfur by ICP emission analysis. is measured, and the value obtained by dividing this amount of sulfur by the absolute dry mass of the fibrous cellulose sample is defined as the amount of sulfur oxo acid groups (mmol/g).

In addition, when measuring the amount of each group introduced by the titration method, if the amount of one drop of alkali (e.g. aqueous sodium hydroxide solution) dropped is too large, or if the titration interval is too short, the amount introduced will be lower than originally expected. Accurate values may not be obtained.
Although there are no particular restrictions on conditions such as an appropriate dropping amount and titration interval, conditions such as titrating a 0.1N aqueous sodium hydroxide solution at a rate of 10 to 50 μL every 5 to 30 seconds are preferred.
In addition, in order to eliminate the influence of carbon dioxide dissolved in the fibrous cellulose-containing slurry, it is desirable to measure while blowing an inert gas such as nitrogen gas into the slurry from 15 minutes before the start of titration until the end of titration. .
The measurement of the amount of each group introduced by the method described above is applied to fibrous cellulose with an average fiber width of 1,000 nm or less, and when measuring the amount of ionic groups in pulp fibers with an average fiber width of more than 1,000 nm. For this purpose, the pulp fibers are pulverized and then measured.

[Method for producing fibrous cellulose]
- Fiber raw material containing cellulose Fibrous cellulose can be produced from a fiber raw material containing cellulose (hereinafter also simply referred to as "fiber raw material").
The fiber raw material is not particularly limited, but it is preferable to use pulp because it is easily available and inexpensive.
The number of fiber raw materials used when manufacturing fibrous cellulose may be one type or two or more types.

Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp.
Wood pulp is not particularly limited, but includes, for example, hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), and unbleached kraft pulp (UKP). ) and chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemical ground wood pulp (CGP), ground wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Mechanical pulp is mentioned.
Non-wood pulps are not particularly limited, and include, for example, cotton-based pulps such as cotton linters and cotton lint, and non-wood-based pulps such as hemp, wheat straw, bamboo, and bagasse.
The deinked pulp is not particularly limited, but includes, for example, deinked pulp made from waste paper.

Among the above-mentioned pulps, wood pulp and deinked pulp, for example, are preferable in terms of availability. In addition, among wood pulps, the cellulose ratio is high and the yield of fibrous cellulose obtained after the fibrillation process described below is high, and the decomposition of cellulose in the pulp is small and the fibrous form of long fibers with a large axial ratio. From the standpoint of being able to obtain cellulose, chemical pulp is more preferred, and kraft pulp and sulfite pulp are even more preferred.

As the fiber raw material, for example, cellulose contained in sea squirts or bacterial cellulose produced by acetic acid bacteria can be used.
Furthermore, instead of the fiber raw material, fibers formed from linear nitrogen-containing polysaccharide polymers such as chitin and chitosan can also be used.

[Method for producing fibrous cellulose having ionic groups]
The above-mentioned method for producing fibrous cellulose having ionic groups includes an ionic group introduction step of introducing ionic groups into fiber raw materials, a washing step, an alkali treatment step (neutralization step), and a fibrillation treatment step. Preferably, the method includes an acid treatment step instead of or in addition to the washing step.

(Ionic group introduction step)
The ionic group introduction step includes, for example, a phosphorus oxo acid group introduction step, a carboxy group introduction step, a sulfur oxo acid group introduction step, a xanthate group introduction step, a phosphonic group introduction step, a phosphine group introduction step, a sulfone group introduction step, and a cationic group introduction step. Examples include a step of introducing a sexual group.

-Phosphorus oxoacid group introduction process-
In the step of introducing a phosphorus oxo acid group, for example, at least one compound selected from compounds that can introduce a phosphorus oxo acid group (hereinafter also referred to as "compound A") by reacting with a hydroxyl group possessed by the fiber raw material is added to the fiber. Examples include a step of acting on raw materials.
Through this step, fibrous cellulose having phosphorus oxo acid groups is obtained.

In the phosphoric acid group introduction step, at least one compound selected from urea and its derivatives (hereinafter referred to as "compound B ) or in the absence of compound B.

An example of a method for causing compound A to act on a fiber raw material in the presence of compound B includes a method of mixing compound A and compound B with a fiber raw material in a dry state, a wet state, or a slurry state. Among these, it is preferable to use dry or wet fiber raw materials, and it is particularly preferable to use dry fiber raw materials, since the reaction uniformity is high. Although the form of the dry fiber raw material is not particularly limited, it is preferably cotton-like or thin sheet-like, for example.

As a method for mixing compound A and compound B with the fiber raw material, each of compound A and compound B is mixed with the fiber raw material in the form of a powder, a solution dissolved in a solvent, or a state in which it is heated to a temperature above the melting point and melted. There are several methods. Among these, it is preferable to add them in the form of a solution dissolved in a solvent, particularly an aqueous solution, since the reaction is highly uniform.
In addition, when mixing, compound A and compound B may be added to the fiber raw material at the same time or separately, or may be added as a mixture in which compound A and compound B are mixed in advance. It's okay.

The method of mixing Compound A and Compound B with the fiber raw material is not particularly limited, but when Compound A and Compound B are in the form of a solution, the fiber raw material is immersed in a solution containing Compound A and Compound B, and the fiber material is mixed with the fiber raw material. The solution containing Compound A and Compound B may be taken out after the raw material absorbs the solution, or the solution containing Compound A and Compound B may be dropped onto the fiber raw material.
Note that the required amount of Compound A and Compound B may be mixed with the fiber raw material, or after mixing the excess amount of Compound A and Compound B with the fiber raw material, excess Compound A and Compound B may be removed by squeezing, filtration, etc. May be removed.

The compound A is preferably a compound that has a phosphorus atom and is capable of forming an ester bond with cellulose, and specific examples include phosphoric acid, phosphates, phosphorous acid, phosphites, and dehydration condensation. Examples include phosphoric acid, dehydrated condensed phosphate, and phosphoric anhydride (diphosphorus pentoxide).
As the phosphoric acid, phosphoric acid of various purity can be used. For example, 100% phosphoric acid (orthophosphoric acid) or 85% phosphoric acid can be used.
Examples of phosphorous acid include 99% phosphorous acid (phosphonic acid).
Dehydrated condensed phosphoric acid is a compound in which two or more molecules of phosphoric acid are condensed through a dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid.
Examples of phosphates, phosphites, and dehydrated condensed phosphates include lithium salts, sodium salts, potassium salts, and ammonium salts of phosphoric acid, phosphorous acid, or dehydrated condensed phosphoric acid, which are It can be made into peace.

Among these, phosphoric acid, A sodium salt of phosphoric acid, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferred, and phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, or ammonium dihydrogen phosphate is more preferred.

The amount of compound A added to the fiber raw material is not particularly limited, but for example, when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atoms added to 100 parts by mass of the fiber raw material (absolutely dry mass) is preferably The content is 0.5 parts by mass or more and 100 parts by mass or less, more preferably 1 part by mass or more and 50 parts by mass or less, and even more preferably 2 parts by mass or more and 30 parts by mass or less.
By controlling the amount of compound A added to the fiber raw material within the above range, the yield of the obtained fibrous cellulose can be further improved. On the other hand, by controlling the amount of compound A added to the fiber raw material to be equal to or less than the above upper limit, it is possible to balance the effect of improving the yield of the obtained fibrous cellulose with cost.

As described above, the compound B is at least one selected from urea and its derivatives. Specific examples of the compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, and 1-ethylurea.

From the viewpoint of improving the uniformity of the reaction, it is preferable to use compound B as an aqueous solution. Further, from the viewpoint of further improving the uniformity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.
The amount of compound B added to 100 parts by mass of the fiber raw material (absolutely dry mass) is not particularly limited, but is preferably 1 part by mass or more and 500 parts by mass or less, more preferably 10 parts by mass or more and 400 parts by mass or less, and even more preferably 100 parts by mass. Parts or more and 350 parts by mass or less.

In the reaction between the fiber raw material and compound A, in addition to compound B, for example, at least one selected from amides and amines may be added to the reaction system.
Examples of amides include formamide, dimethylformamide, acetamide, and dimethylacetamide.
Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine.
Among these, triethylamine is particularly preferred because it functions as a good reaction catalyst.

In the step of introducing phosphorus oxoacid groups, it is preferable to heat the mixture after mixing the fiber raw material and compound A and the like.

As the heat treatment temperature, it is preferable to select a temperature at which phosphorus oxo acid groups can be efficiently introduced while suppressing thermal decomposition and hydrolysis reactions of the fiber raw material.
The heat treatment temperature is preferably 50°C or more and 300°C or less, more preferably 100°C or more and 250°C or less, and even more preferably 130°C or more and 200°C or less.
The heat treatment time is preferably from 1 second to 300 minutes, more preferably from 1 second to 1,000 seconds, even more preferably from 10 seconds to 800 seconds, after water is substantially removed from the fiber raw material. It is.
By setting the heating temperature and heating time within appropriate ranges, it becomes easy to bring the amount of phosphorus oxo acid groups introduced within a preferable range.

In the heat treatment, for example, a method in which Compound A is added to a thin sheet-shaped fiber raw material by a method such as impregnation, and then heated, or a method in which the fiber raw material and Compound A are heated while kneading or stirring with a kneader or the like. can be adopted. These methods make it possible to suppress unevenness in the concentration of compound A in the fiber raw material and more uniformly introduce phosphorus oxoacid groups onto the surface of the cellulose fibers contained in the fiber raw material. This is because when water molecules move to the surface of the fiber raw material due to drying by heating, the dissolved compound A is attracted to the water molecules by surface tension and similarly moves to the surface of the fiber raw material (i.e., the amount of compound A This is thought to be due to the fact that it is possible to suppress the occurrence of density unevenness.

For the heat treatment, devices having various heat media can be used, such as a stirring dryer, a rotary dryer, a disc dryer, a roll-type heating device, a plate-type heating device, a fluidized bed dryer, and a band-type dryer. A drying device, a filtration drying device, a vibration fluid drying device, a flash drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device can be used.

In addition, the heating device used for the heat treatment is used, for example, in the case where a slurry-like fiber raw material is used, the water retained in the slurry, and the dehydration condensation (phosphoric acid It is preferable that the apparatus be capable of constantly discharging moisture generated during the esterification reaction to the outside of the apparatus system. An example of such a heating device is a blower type oven.
By constantly draining water from the equipment system, it is possible to suppress the hydrolysis reaction of phosphate ester bonds, which is the reverse reaction of phosphoric acid esterification, and also to suppress acid hydrolysis of sugar chains in fibers. can. Therefore, fibrous cellulose with a high axial ratio can be easily obtained.

The step of introducing a phosphorus oxoacid group may be carried out at least once, but it can also be carried out twice or more. By performing the phosphorus oxo acid group introduction step two or more times, a large number of phosphorus oxo acid groups can be introduced into the fiber raw material. A preferred embodiment includes a method in which the phosphorus oxoacid group introduction step is carried out twice.

The amount of phosphorus oxoacid group introduced into the fiber raw material is preferably 0.10 mmol/g or more, more preferably 0.20 mmol/g or more, even more preferably 0.50 mmol/g or more, particularly per 1 g (mass) of fibrous cellulose. Preferably it is 1.00 mmol/g or more. In addition, the amount of phosphorus oxo acid groups introduced into the fiber raw material is preferably 5.20 mmol/g or less, more preferably 3.65 mmol/g or less, even more preferably 3.00 mmol/g or less per 1 g (mass) of fibrous cellulose. It is.
When the amount of phosphorus oxo acid groups introduced is within the above range, the fibrous cellulose can be easily refined and the stability of the fibrous cellulose can be improved.

- Carboxy group introduction process -
In the carboxy group introduction step, the fiber raw material is subjected to oxidation treatment such as ozone oxidation, Fenton method, TEMPO oxidation treatment, treatment with a compound having a group derived from carboxylic acid or its derivative, or treatment with a compound having a group derived from carboxylic acid. This can be carried out by treatment such as treatment with an acid anhydride or a derivative thereof.

Compounds having carboxylic acid-derived groups are not particularly limited, but include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, and itaconic acid, citric acid, aconitic acid, etc. Examples include tricarboxylic acid compounds.
Derivatives of compounds having a group derived from carboxylic acid are not particularly limited, but include, for example, imidized acid anhydrides of compounds having a carboxy group.
The imidized product of an acid anhydride of a compound having a carboxyl group is not particularly limited, but examples thereof include imidized products of dicarboxylic acid compounds such as maleimide, succinimide, and phthalic acid imide.

Acid anhydrides of compounds having groups derived from carboxylic acid are not particularly limited, but include dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Examples include acid anhydrides.
Derivatives of acid anhydrides of compounds having a group derived from carboxylic acid are not particularly limited, but include, for example, acid anhydrides of compounds having a carboxy group such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride, etc. Examples include compounds in which at least some of the hydrogen atoms are substituted with substituents such as alkyl groups and phenyl groups.

In the carboxyl group introduction step, when TEMPO oxidation treatment is performed, it is preferable to perform the treatment under conditions where the pH is 6 or more and 8 or less, for example. Such treatment is also referred to as neutral TEMPO oxidation treatment.
In the neutral TEMPO oxidation treatment, for example, pulp as a fiber raw material and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) etc. as a catalyst are added to a sodium phosphate buffer (pH = 6.8). This can be done by adding nitroxy radicals and sodium hypochlorite as a sacrificial reagent. Furthermore, by coexisting sodium chlorite, aldehyde generated during the oxidation process can be efficiently oxidized to carboxy groups.

Further, the TEMPO oxidation treatment may be performed under conditions where the pH is 10 or more and 11 or less. Such treatment is also referred to as alkaline TEMPO oxidation treatment.
The alkaline TEMPO oxidation treatment can be performed, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a cocatalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. I can do it.

The amount of carboxy groups introduced into the fiber raw material varies depending on the type of substituent, but for example, when introducing carboxy groups by TEMPO oxidation, it is preferably 0.10 mmol/g or more per 1 g (mass) of fibrous cellulose, and more. Preferably 0.20 mmol/g or more, more preferably 0.50 mmol/g or more, particularly preferably 0.90 mmol/g or more, preferably 2.5 mmol/g or less, more preferably 2.20 mmol/g or less, More preferably, it is 2.00 mmol/g or less.
In addition, when introducing a carboxymethyl group, the amount may be, for example, 5.8 mmol/g or less per 1 g (mass) of fibrous cellulose.

-Sulfur oxoacid group introduction process-
Examples of the step of introducing a sulfur oxo acid group include a step of reacting a hydroxyl group of the fiber raw material with a sulfur oxo acid.

In the sulfur oxo acid group introduction step, for example, in place of compound A in the phosphorus oxo acid group introduction step described above, at least one compound selected from compounds capable of introducing sulfur oxo acid groups by reacting with a hydroxyl group possessed by the fiber raw material is used. (hereinafter also referred to as "compound C").
In the sulfur oxo acid group introduction step, it is preferable to use the compound B in the same manner as in the phosphorus oxo acid group introduction step described above.

Compound C is preferably a compound that has a sulfur atom and is capable of forming an ester bond with cellulose, and specific examples include sulfuric acid, sulfates, sulfites, sulfites, and sulfuric acid amide.
As the sulfuric acid, sulfuric acid of various purity can be used, for example, 96% sulfuric acid (concentrated sulfuric acid) can be used.
Examples of sulfite include 5% sulfite water.
Examples of the sulfate or sulfite include lithium, sodium, potassium, and ammonium salts of sulfuric acid or sulfite, which can have various degrees of neutralization.
Examples of sulfuric acid amides include sulfamic acid.

In the sulfur oxoacid group introduction step, it is preferable that the fiber raw material, compound C, and compound B are mixed and then subjected to heat treatment.

As the heat treatment temperature, it is preferable to select a temperature at which sulfur oxoacid groups can be efficiently introduced while suppressing thermal decomposition and hydrolysis reactions of the fiber raw material.
The heat treatment temperature is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher. Further, the heat treatment temperature is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower.

In the heat treatment step, it is preferable to heat until substantially no moisture is left. Therefore, the heat treatment time varies depending on the amount of water contained in the fiber raw material, etc., but is preferably, for example, 10 seconds or more and 10,000 seconds or less.

For the heat treatment, devices having various heat media can be used, such as a stirring dryer, a rotary dryer, a disc dryer, a roll-type heating device, a plate-type heating device, a fluidized bed dryer, and a band-type dryer. A drying device, a filtration drying device, a vibration fluid drying device, a flash drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device can be used.

The amount of sulfur oxoacid group introduced into the fiber raw material is preferably 0.05 mmol/g or more, more preferably 0.10 mmol/g or more, still more preferably 0.20 mmol/g or more, and even more preferably 0.50 mmol/g or more. , particularly preferably 0.90 mmol/g or more. Further, the amount of sulfur oxoacid groups introduced into the fiber raw material is preferably 5.00 mmol/g or less, more preferably 3.00 mmol/g or less.
When the amount of sulfur oxoacid groups introduced is within the above range, the fibrous cellulose can be easily refined and the stability of the fibrous cellulose can be improved.

-Oxidation step using chlorine-based oxidizing agent (second carboxyl group introduction step)-
As the ionic substituent introduction step, for example, an oxidation step using a chlorine-based oxidizing agent may be performed. In the oxidation step using a chlorine-based oxidizing agent, carboxy groups can be introduced into the fiber raw material by adding the chlorine-based oxidizing agent to the fiber raw material having a hydroxyl group in a wet or dry state and performing a reaction.
Note that after the reaction, excess reaction reagents, by-products, etc. may be washed with water and removed by filtration or the like.

Examples of chlorine-based oxidizing agents include hypochlorous acid, hypochlorite, chlorous acid, chlorite, chloric acid, chlorate, perchloric acid, perchlorate, and chlorine dioxide. . Among these, sodium hypochlorite, sodium chlorite, and chlorine dioxide are preferred from the viewpoint of substituent introduction efficiency, fibrillation efficiency, cost, ease of handling, and the like.
The chlorine-based oxidizing agent may be added as a reagent to the fiber raw material as it is, or may be dissolved in an appropriate solvent and then added to the fiber raw material.
One type of chlorine-based oxidizing agent may be used, or two or more types may be used.

The concentration of the chlorine-based oxidizing agent in the solution containing the fiber raw material in the oxidation step using the chlorine-based oxidizing agent is preferably 1% by mass or more and 43% by mass or less, more preferably 5% by mass or more and 40% by mass or less, in terms of effective chlorine concentration, for example. It is not more than 10% by mass and not more than 38% by mass.
The amount of the chlorine-based oxidizing agent added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 10 parts by mass or more and 10,000 parts by mass or less, and even more preferably 100 parts by mass or more. ,000 parts by mass or less.

The reaction temperature in the oxidation step using a chlorine-based oxidizing agent is preferably 10°C or more and 100°C or less, more preferably 15°C or more and 80°C or less, and even more preferably 20°C or more and 60°C or less.

The reaction time between the fiber raw material and the chlorine-based oxidizing agent may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and even more preferably 20 minutes or more and 400 minutes or less. minutes or less.
The pH during the reaction in the oxidation step using a chlorine-based oxidizing agent is preferably 5 or more and 14 or less, more preferably 7 or more and 14 or less, and still more preferably 9 or more and 13 or less.
Further, at the start of the reaction, it is preferable to keep the pH constant (eg, pH 11) during the reaction while adding hydrochloric acid or sodium hydroxide as appropriate.

-Carboxyalkylation step (third carboxy group introduction step)-
As the ionic substituent introduction step, for example, a carboxyalkylation step may be performed. In the carboxyalkylation step, a compound having a reactive group and a carboxy group (hereinafter also referred to as "compound D") is used as an essential component, and the following alkali compound and/or the above-mentioned compound B are used as optional components. A carboxy group can be introduced into the fiber raw material by adding it to a fiber raw material having a hydroxyl group in a wet or dry state and carrying out the reaction.
Note that after the reaction, excess reaction reagents, by-products, etc. may be washed with water and removed by filtration or the like.

Examples of the reactive group in the compound D include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
As Compound D, monochloroacetic acid, sodium monochloroacetate, 2-chloropropionic acid, 3-chloropropionic acid, and sodium 2-chloropropionate are used in terms of substituent introduction efficiency, fibrillation efficiency, cost, ease of handling, etc. , sodium 3-chloropropionate is preferred.
Compound D may be used alone or in combination of two or more. The same applies to other compounds.
Further, as an optional component, it is also preferable to use the above-mentioned compound B in the same manner, and it is preferable that the amount added is also as described above.

Compound D may be added as a reagent to the fiber raw material as it is, or may be added after being dissolved in an appropriate solvent.
It is preferable that the fiber raw material is converted into alkali cellulose in advance or simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The amount of compound D added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, even more preferably 5 parts by mass or more and 1,000 parts by mass or less. Parts by mass or less.

The reaction temperature in the carboxyalkylation step is preferably 50°C or more and 300°C or less, more preferably 100°C or more and 250°C or less, and still more preferably 130°C or more and 200°C or less.

The reaction time in the carboxyalkylation step may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 3 minutes or more and 500 minutes or less, and even more preferably 5 minutes or more and 400 minutes or less. .

-Xanthate group introduction process-
Examples of the xanthate group introduction step include a step of substituting the hydroxyl group of the fiber raw material with a xanthate group represented by the following formula (3) (obtaining a xanthate group-introduced fiber).
-OCSS-M ⁺ ...(3)
[M ⁺ is at least one selected from hydrogen ions, monovalent metal ions, ammonium ions, aliphatic or aromatic ammonium ions. ]

The xanthate group introduction step preferably includes a step of first performing an alkali treatment of treating the fiber raw material with an alkaline solution to obtain alkali cellulose.
Examples of the alkaline solution include alkali metal hydroxide aqueous solutions and alkaline earth metal hydroxide aqueous solutions. Among these, the alkaline solution is preferably an aqueous solution of alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, and particularly preferably an aqueous sodium hydroxide solution.

When the alkaline solution is an aqueous alkali metal hydroxide solution, the concentration of alkali metal hydroxide in the aqueous alkali metal hydroxide solution is preferably 4% by mass or more, more preferably 5% by mass or more, and preferably 9% by mass or less. be.
By setting the concentration of alkali metal hydroxide at or above the above lower limit, mercerization of cellulose can be sufficiently progressed, and the amount of by-products generated during the subsequent xanthate formation can be reduced, resulting in , the yield of xanthate group-introduced fibers can be increased. Thereby, the defibration process described below can be performed more effectively. In addition, by setting the concentration of alkali metal hydroxide at or below the upper limit value, it is possible to prevent the alkali metal hydroxide aqueous solution from penetrating into the crystalline region of cellulose while promoting mercerization. The type I crystal structure is easily maintained, and the yield of fine fibrous cellulose can be further increased.

The time for the alkali treatment is preferably 30 minutes or more, more preferably 1 hour or more, and preferably 6 hours or less, more preferably 5 hours or less.
By controlling the alkali treatment time within the above range, the final yield can be increased and the productivity of the xanthate group-introduced fibers can be increased.

It is preferable that the alkali cellulose obtained by the alkali treatment is then subjected to solid-liquid separation to remove as much of the aqueous solution as possible. Thereby, the water content during the subsequent xanthate treatment can be reduced and the reaction can be accelerated.
Examples of the solid-liquid separation method include common dehydration methods such as centrifugation and filtration. The concentration of alkali metal hydroxide contained in the alkali cellulose after solid-liquid separation is preferably 3% by mass or more and 8% by mass or less based on the total mass of the alkali cellulose after solid-liquid separation.

In the xanthate group introduction step, it is preferable to perform a xanthate treatment step after the alkali treatment.
In the xanthate treatment step, alkali cellulose is reacted with carbon disulfide (CS ₂ ) to convert (-O-M ⁺ ) groups into (-OCSS-M ⁺ ) groups, thereby obtaining xanthate group-introduced fibers. I can do it.

In the xanthating treatment, it is preferable to supply 10 parts by mass or more of carbon disulfide to 100 parts by mass of bone dry cellulose in the alkali cellulose.
Further, in the xanthate treatment, the contact time between carbon disulfide and alkali cellulose is preferably 30 minutes or more, more preferably 1 hour or more.
When carbon disulfide comes into contact with alkali cellulose, xanthate formation progresses rapidly, but since it takes time for carbon disulfide to penetrate into the inside of alkali cellulose, it is preferable that the reaction time is within the above range. .
On the other hand, the contact time between carbon disulfide and alkali cellulose is preferably 6 hours or less, so that the alkali cellulose is sufficiently penetrated into the alkali cellulose lumps after dehydration, and xanthate formation is possible. You can almost complete it.

The reaction temperature in the xanthate treatment is preferably 46°C or lower.
By setting the reaction temperature within the above range, decomposition of alkali cellulose can be easily suppressed. In addition, by setting the reaction temperature within the above range, it becomes easier to react uniformly, thereby suppressing the production of by-products, and furthermore, suppressing the xanthate groups introduced into the fibers from being removed from the fibers. can.

The amount of xanthate groups introduced into the fiber raw material is preferably 0.60 mmol/g or more, more preferably 0.70 mmol/g or more, even more preferably 0.80 mmol/g or more, more preferably 1.00 mmol/g or more, especially Preferably it is 1.20 mmol/g or more. Further, the amount of xanthate groups introduced into the fiber raw material is preferably 5.00 mmol/g or less, more preferably 3.00 mmol/g or less.
When the amount of xanthate groups introduced is within the above range, a scaffolding material with excellent transparency and yellowing resistance can be easily obtained.

- Phosphonic group or phosphine group introduction step (phosphoalkylation step) -
In the step of introducing a phosphonic group or a phosphine group (phosphoalkylation step), for example, a compound having a reactive group and a phospho group or a phosphine group (hereinafter also referred to as "compound E") is used as an essential component, and as an optional component. A phosphonic group or a phosphine group can be introduced into the fiber raw material by adding the alkali compound and/or the above-mentioned compound B to the fiber raw material having a hydroxyl group in a wet or dry state and carrying out the reaction.
After the reaction, excess reaction reagents, by-products, etc. may be washed with water and removed by filtration or the like.

Examples of the reactive group in the compound E include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
Examples of compound E include vinylphosphonic phosphoric acid, phenylvinylphosphonic acid, and phenylvinylphosphinic acid. Among these, vinylphosphonic phosphoric acid is preferred from the viewpoints of substituent introduction efficiency, fibrillation efficiency, cost, ease of handling, and the like.
Compound E may be used alone or in combination of two or more. The same applies to other compounds.
Further, as an optional component, it is also preferable to use the above-mentioned compound B in the same manner, and it is preferable that the amount added is also as described above.

Compound E may be added as a reagent to the fiber raw material as it is, or may be added after being dissolved in an appropriate solvent.
It is preferable that the fiber raw material is converted into alkali cellulose in advance or simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The amount of compound E added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, even more preferably 5 parts by mass or more and 1,000 parts by mass or less. Parts by mass or less.

The reaction temperature in the phosphonic group or phosphine group introduction step is preferably 50°C or higher and 300°C or lower, more preferably 100°C or higher and 250°C or lower, and even more preferably 130°C or higher and 200°C or lower.

The reaction time in the phosphonic group or phosphine group introduction step may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and even more preferably 20 minutes or more and 400 minutes or less. It is as follows.

- Sulfone group introduction step (sulfoalkylation step) -
In the sulfone group introduction step (sulfoalkylation step), for example, a compound having a reactive group and a sulfone group (hereinafter also referred to as "compound F") as an essential component, and the above-mentioned alkali compound and as an optional component. A sulfone group can be introduced into the fiber raw material by adding/or the above-mentioned compound B to the fiber raw material having a hydroxyl group in a wet or dry state and performing a reaction.
Note that after the reaction, excess reaction reagents, by-products, etc. may be washed with water and removed by filtration or the like.

Examples of the reactive group in compound F include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
Examples of compound F include sodium 2-chloroethanesulfonate, sodium vinylsulfonate, sodium p-styrenesulfonate, and 2-acrylamido-2-methylpropanesulfonic acid. Among these, sodium vinylsulfonate is preferred from the viewpoints of substituent introduction efficiency, fibrillation efficiency, cost, ease of handling, and the like.
Compound F may be used alone or in combination of two or more. The same applies to other compounds.
Further, as an optional component, it is also preferable to use the above-mentioned compound B in the same manner, and it is preferable that the amount added is also as described above.

Compound F may be added as a reagent to the fiber raw material as it is, or may be added after being dissolved in an appropriate solvent.
It is preferable that the fiber raw material is converted into alkali cellulose in advance or simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The amount of compound F added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less. Parts by mass or less.

The reaction temperature in the sulfone group introduction step is preferably 50°C or more and 300°C or less, more preferably 100°C or more and 250°C or less, and even more preferably 130°C or more and 200°C or less.

The reaction time in the sulfone group introduction step may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and even more preferably 15 minutes or more and 400 minutes or less. .

-Cationic group introduction step (cationization step)-
In the cationic group introduction step (cationization step), a compound having a reactive group and a cationic group (hereinafter also referred to as "compound G") is used as an essential component, and the above-mentioned alkali compound and/or as an optional component. Alternatively, a cationic group can be introduced into the fiber raw material by adding the above-mentioned compound B to a wet or dry fiber raw material having a hydroxyl group and performing a reaction.
Note that after the reaction, excess reaction reagents, by-products, etc. may be washed with water and removed by filtration or the like.

Examples of the reactive group in compound G include a halogenated alkyl group, a vinyl group, and an epoxy group (glycidyl group).
As compound G, glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride, etc. are preferable from the viewpoints of substituent introduction efficiency, fibrillation efficiency, cost, ease of handling, and the like.
Compound G may be used alone or in combination of two or more. The same applies to other compounds.
Further, as an optional component, it is also preferable to use the above-mentioned compound B in the same manner, and it is preferable that the amount added is also as described above.

Compound G may be added as a reagent to the fiber raw material as it is, or may be added after being dissolved in an appropriate solvent.
It is preferable that the fiber raw material is converted into alkali cellulose in advance or simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The amount of compound G added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and even more preferably 5 parts by mass or more and 1,000 parts by mass or less. Parts by mass or less.

The reaction temperature in the cationic group introduction step is preferably 50°C or more and 300°C or less, more preferably 100°C or more and 250°C or less, and even more preferably 130°C or more and 200°C or less.

The reaction time in the cationic group introduction step may vary depending on the reaction temperature, but is preferably 1 minute or more and 1,000 minutes or less, more preferably 5 minutes or more and 500 minutes or less, and even more preferably 10 minutes or more and 400 minutes or less. be.

(Washing process)
In the method for producing fibrous cellulose having ionic groups, it is preferable to perform a washing step on the ionic group-introduced fibers obtained in the ionic group-introducing step.
The washing step can be performed, for example, by washing the ionic group-introduced fiber with water or an organic solvent. Further, the cleaning process may be performed after each process described below, and the number of times of cleaning performed in each cleaning process is not particularly limited.

(Alkali treatment process (neutralization process))
In the method for producing fibrous cellulose having ionic groups, it is preferable to perform an alkali treatment step (neutralization step) on the fiber raw material between the ionic group introduction step and the defibration step described below. .

The alkali treatment step is not particularly limited, but includes, for example, a method of immersing the ionic group-introduced fiber in an alkaline solution.
When the ionic group-introduced fiber has an anionic group, the alkali treatment step may be a neutralization treatment/ion exchange treatment of the anionic group. In this case, the temperature of the alkaline solution is preferably room temperature.

The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkali compound or an organic alkali compound. For example, it is preferable to use sodium hydroxide or potassium hydroxide because of its high versatility.
One type of alkali compound may be used, or two or more types may be used.

The solvent contained in the alkaline solution may be either water or an organic solvent. Among these, polar solvents such as water and polar organic solvents exemplified by alcohol are preferred, and aqueous solvents containing at least water are more preferred.
The alkaline solution is preferably, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution because of its high versatility.

The amount of alkaline solution used in the alkali treatment step is not particularly limited, but is preferably 100 parts by mass or more and 100,000 parts by mass or less, more preferably 1,000 parts by mass, based on 100 parts by mass of the absolute dry mass of the ionic group-introduced fiber. It is not less than 10,000 parts by mass and not more than 10,000 parts by mass.

The temperature of the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5°C or higher and 80°C or lower, more preferably 10°C or higher and 60°C or lower.
The immersion time of the ionic group-introduced fibers in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, more preferably 10 minutes or more and 20 minutes or less.

In order to reduce the amount of alkaline solution used in the alkali treatment process, a cleaning process is performed in which the ionic group-introduced fibers are washed with water, an organic solvent, etc. after the ionic group introduction process and before the alkali treatment process. It is preferable.
In addition, after the alkali treatment process and before the defibration process, the ionic group-introduced fibers that have been subjected to the alkali treatment process are washed with water, an organic solvent, etc. in order to improve handling. is preferred.

(Acid treatment process)
In the method for producing fibrous cellulose having ionic groups, the ionic group-introduced fibers may be subjected to acid treatment between the step of introducing the ionic groups and the defibration step described below.
For example, the ionic group introduction step, the acid treatment step, the alkali treatment step, and the fibrillation treatment step may be performed in this order.

The acid treatment step is not particularly limited, but includes, for example, a method of immersing the ionic group-introduced fiber in an acidic solution containing an acid.
When the ionic group-introduced fiber has a cationic group, the acid treatment step may be a neutralization treatment/ion exchange treatment of the cationic group. In this case, the temperature of the acidic liquid is preferably room temperature.

The concentration of the acidic liquid used is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less.
Further, the pH of the acidic liquid used is not particularly limited, but is preferably 0 or more and 4 or less, more preferably 1 or more and 3 or less.

Examples of acids contained in the acidic liquid include inorganic acids, sulfonic acids, and carboxylic acids.
Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, phosphoric acid, and boric acid.
Examples of the sulfonic acids include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.
Examples of carboxylic acids include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid.
Among these, it is particularly preferable to use hydrochloric acid or sulfuric acid.
One type of acid may be used, or two or more types may be used.

The amount of acidic liquid used in the acid treatment step is not particularly limited, but is preferably 100 parts by mass or more and 100,000 parts by mass or less, more preferably 1,000 parts by mass, based on 100 parts by mass of the absolute dry mass of the ionic group-introduced fiber. It is not less than 10,000 parts by mass and not more than 10,000 parts by mass.

The temperature of the acidic liquid in the acid treatment step is not particularly limited, but is preferably 5°C or higher and 100°C or lower, more preferably 20°C or higher and 90°C or lower.
The immersion time of the ionic group-introduced fibers in the acidic solution in the acid treatment step is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, more preferably 10 minutes or more and 60 minutes or less.

(Defibration process)
In the method for producing fibrous cellulose having ionic groups, it is preferable to defibrate the ionic group-introduced fibers in a defibration process. Through this defibration treatment, fibrous cellulose can be obtained.

In the defibration processing step, for example, a defibration processing device can be used. Defibration processing equipment is not particularly limited, but includes, for example, high-speed defibrators, grinders (stone mill type crushers), high-pressure homogenizers, ultra-high-pressure homogenizers, high-pressure collision type crushers, ball mills, bead mills, disc-type refiners, conical refiners, etc. Axial kneaders, vibratory mills, homomixers (under high speed rotation), ultrasonic dispersers, beaters can be used. Among these, it is more preferable to use a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer because they are less affected by the grinding media and have less risk of contamination.

In the fibrillation treatment step, for example, it is preferable that the ionic group-introduced fibers be diluted with a dispersion medium to form a slurry. As the dispersion medium, one or more types selected from water and organic solvents such as polar organic solvents can be used.
The polar organic solvent is not particularly limited, but for example, alcohols, polyhydric alcohols, ketones, ethers, esters, and aprotic polar solvents are preferred.
Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, and isobutyl alcohol.
Examples of polyhydric alcohols include ethylene glycol, propylene glycol, and glycerin.
Examples of ketones include acetone and methyl ethyl ketone (MEK).
Examples of the ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, and propylene glycol monomethyl ether.
Examples of esters include ethyl acetate and butyl acetate.
Examples of the aprotic polar solvent include dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methyl-2-pyrrolidinone (NMP).

In the fibrillation process, when the ionic group-introduced fibers are diluted with a dispersion medium to form a slurry, the solid content concentration of the ionic group-introduced fibers in the slurry may be appropriately set.
Moreover, the slurry may contain solid content other than the ionic group-introduced fibers.

<Negative radiation-sensitive component>
This scaffolding material contains a negative radiation-sensitive component (hereinafter also simply referred to as "radiation-sensitive component").
The radiation-sensitive component is not particularly limited as long as it does not contain fibrous cellulose and contains a polymerizable compound and a polymerization initiator. It may also contain known components other than these, but the radiation-sensitive component does not contain fibrous cellulose. It is preferable to consist of only a compound and a polymerization initiator.
The number of radiation-sensitive components used in the present scaffolding material may be one or two or more.

The radiation-sensitive component is not particularly limited as long as it is a negative-type radiation-sensitive component. The radiation-sensitive component has the property of being polymerized and/or crosslinked by the action of reactive active species such as radicals generated from the polymerization initiator contained in the radiation-sensitive component upon irradiation with radiation.

When a radiation-sensitive component is irradiated with radiation, its solubility in a solvent or the like decreases. It is preferable that the radiation-sensitive component is a composition whose solubility in a solvent etc. decreases due to a reaction caused by reactive active species such as radicals generated by radiation irradiation. More preferably, the composition is one in which solubility in a solvent decreases due to a polymerization reaction induced by radicals.
When a part of this scaffolding material containing such a radiation-sensitive component is irradiated with radiation, the polymerization reaction (crosslinking reaction) of the polymerizable compound does not proceed in the area that is not irradiated with radiation (unexposed area). It has high solubility in developing solutions and the like (particularly water and water-containing solvents). On the other hand, in the area irradiated with radiation (exposed area), the polymerization reaction (crosslinking reaction) of the polymerizable compound progresses, and the solubility in developing solutions (especially water and water-containing solvents) decreases, resulting in a negative tone. Can exhibit radiation sensitivity.

Here, radiation includes visible light, ultraviolet rays, far ultraviolet rays, electron beams (charged particle beams), and X-rays. Among these, ultraviolet light is preferred, and light with a wavelength of 313 nm or more is more preferred.

The content of the radiation-sensitive component (solid content) in this scaffolding material is 20 parts by mass based on 100 parts by mass of fibrous cellulose, from the viewpoint of easily forming a patterned hydrogel scaffolding material. The content is preferably 60 parts by mass or more, more preferably 100 parts by mass or more, and 200 parts by mass or less, preferably 180 parts by mass or less, and more preferably 140 parts by mass or less.

The radiation-sensitive component is preferably a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof, and is soluble in either water, methanol, or ethanol, and has a high solubility in water. It is particularly preferable that the component has
When a fibrous cellulose dispersion is used as a raw material for the present scaffolding material, the radiation-sensitive component is dissolved in at least one selected from water, alcohol, and a mixed solvent thereof. It is preferable because it has high affinity and can prepare a uniform coating liquid or slurry for papermaking, and facilitates the coating process or papermaking process described below. In addition, the radiation-sensitive component in the unexposed area can be easily removed using a developer (particularly water and a solvent containing water), and the radiation-sensitive component can be removed to easily form a patterned hydrogel scaffold. This is preferable because it allows

Note that the radiation-sensitive component is a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof. is an alcohol having 1 to 4 carbon atoms, more preferably an alcohol having 1 to 3 carbon atoms), or a mixed solvent of water and an alcohol having 1 to 6 carbon atoms at 25°C and atmospheric pressure. means that 1 g or more is dissolved.

[Polymerizable compound]
The polymerizable compound is not particularly limited, and is preferably a compound having a polymerizable unsaturated bond, and more preferably a compound containing a plurality of polymerizable unsaturated bonds.
As the polymerizable compound, a polymer, an oligomer, or a monomer may be used. Among these, it is preferable to use oligomers or monomers.
As the polymerizable compound used in the radiation-sensitive component, one type or two or more types may be used.

Examples of the polymerizable unsaturated bonds include carbon-carbon double bonds (hereinafter also referred to as "ethylenic unsaturated bonds") and carbon-carbon triple bonds. Among these, ethylenically unsaturated bonds are preferable.

The ethylenically unsaturated bond is preferably derived from a compound having a (meth)acryloyloxy group or a (meth)acrylamide group, more preferably derived from a compound having an acryloyloxy group or an acrylamide group, and is preferably derived from a compound having an acryloyloxy group or an acrylamide group. More preferably, it is derived from a compound having. That is, the polymerizable compound preferably contains a compound having at least one of a (meth)acryloyloxy group and a (meth)acrylamide group, and preferably contains a compound having at least one of an acryloyl group and an acrylamide group. is more preferable, and it is even more preferable to contain a compound having an acrylamide group.

Examples of the skeleton structure of the polymer as the polymerizable compound include polyalkylene glycol (e.g. polyethylene glycol, polypropylene glycol), cellulose derivatives (e.g. hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose), casein, dextrin, polyvinyl. Alcohol, modified polyvinyl alcohol (e.g. acetoacetylated polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene oxide polyvinyl alcohol), polyalkylene oxide (e.g. polyethylene oxide), polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylates, Examples include polyacrylamide, acrylic ester copolymers, urethane copolymers, polyhydroxystyrene copolymers, and polyalkylene imines. Among these, polyethylene glycol, polyethylene oxide, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylamide, acrylic ester copolymer, and polyalkylene imine are particularly preferred.

Examples of the oligomer or monomer in the polymerizable compound include ethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6- Examples include hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 2-hydroxyethyl(meth)acrylate, diethylene glycol monoethyl ether (meth)acrylate, and ω-carboxypolycaprolactone mono(meth)acrylate. It will be done.

Aronix M-220, Aronix M-240, Aronix M-101A, Aronix M-111, Aronix M-113, and Aronix M-101A may be used as the oligomer or monomer. -5300 (manufactured by Toagosei Co., Ltd.), KAYARAD HX-220, R-604 (manufactured by Nippon Kayaku Co., Ltd.), Viscoat 260 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), Light Acrylate 1,9- Examples include bifunctional compounds such as NDA (manufactured by Kyoeisha Chemical Co., Ltd.).

As the oligomer or monomer in the polymerizable compound, a trifunctional or higher functional compound may be used, and examples of the trifunctional or higher functional compound include trifunctional or higher functional (meth)acrylic acid ester, trifunctional or higher functional (meth)acrylamide. is preferred.
Examples of trifunctional or higher-functional (meth)acrylic acid esters include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol penta(meth)acrylate. Pentaerythritol hexa(meth)acrylate;
A mixture of dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate;
Ethylene oxide-modified pentaerythritol tetra(meth)acrylate, tri(2-(meth)acryloyloxyethyl)phosphate, succinic acid-modified pentaerythritol tri(meth)acrylate, succinic acid-modified dipentaerythritol penta(meth)acrylate, tripentaerythritol hepta (meth)acrylate, tripentaerythritol octa(meth)acrylate, isocyanuric acid EO-modified di(meth)acrylate, isocyanuric acid EO-modified tri(meth)acrylate;
A mixture of isocyanuric acid EO-modified di(meth)acrylate and isocyanuric acid EO-modified tri(meth)acrylate;
N,N'-{[(2-(meth)acrylamido-2-[(3-(meth)acrylamidopropoxy)methyl]propane-1,3-diyl)bis(oxy)]bis(propane-1,3- Examples include trifunctional or higher functional (meth)acrylamides such as di(meth)acrylamide.

As the trifunctional or higher functional (meth)acrylic acid ester, commercially available products may be used, such as Aronix M-309, Aronix M-400, Aronix M-405, Aronix M-450, (manufactured by Toagosei Co., Ltd.), KAYARAD TMPTA, DPHA, DPCA-20, DPCA-30, DPCA-60, DPEA-12 (manufactured by Nippon Kayaku Co., Ltd.), Viscoat 295 (Osaka (manufactured by Organic Chemical Industry Co., Ltd.).
As the trifunctional or higher functional (meth)acrylamide, a commercially available product may be used, and examples of the commercially available product include FOM-03006 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.).

In addition, the oligomer or monomer in the polymerizable compound includes a compound having a linear alkylene group and an alicyclic structure and having two or more isocyanate groups, and a compound having one or more hydroxyl group in the molecule. It is also possible to use a polyfunctional (meth)acrylic acid ester such as a polyfunctional urethane acrylate compound obtained by reacting a compound having 3, 4 or 5 (meth)acryloyloxy groups.

The content of the polymerizable compound relative to 100 parts by mass of the solid content of the radiation-sensitive component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and preferably 99 parts by mass or less, more preferably 95 parts by mass or less. It is.
By having the content of the polymerizable compound within the above range, it is possible to form a portion in which the solubility in a developer etc. is sufficiently reduced in the exposed area, and a desired patterned hydrogel scaffold material can be easily formed. be able to.

[Polymerization initiator]
The polymerization initiator is preferably at least one selected from acid generators and photopolymerization initiators, and photopolymerization initiators are more preferable.
When using an acid generator, it can be made into a negative radiation-sensitive component by adding other ingredients.

A photopolymerization initiator is a component that generates active species capable of initiating polymerization of a polymerizable compound in response to radiation.
As the polymerization initiator used in the radiation-sensitive component, one type or two or more types may be used.

Examples of the photopolymerization initiator include radical photopolymerization initiators. A photopolymerization initiator can initiate a crosslinking reaction of a compound having a polymerizable unsaturated bond by exposure to radiation such as visible light, ultraviolet rays, far ultraviolet rays, electron beams, and X-rays. The polymerization initiator is a photo-radical polymerization initiator that generates the most radicals when exposed to ultraviolet rays, furthermore, light with a wavelength of 313 nm or more, particularly light around 365 nm.
Examples of the photoradical polymerization initiator include O-acyloxime compounds, acetophenone compounds, biimidazole compounds, and acylphosphine oxide compounds.

Examples of O-acyloxime compounds include 1-[4-(phenylthio)-2-(O-benzoyloxime)], 1,2-octanedione-1-[4-(phenylthio)-2-(O- benzoyloxime)], ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), 1-[9-ethyl-6- Benzoyl-9H-carbazol-3-yl]-octan-1-one oxime-O-acetate, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-ethane-1- One oxime-O-benzoate, 1-[9-n-butyl-6-(2-ethylbenzoyl)-9H-carbazol-3-yl]-ethan-1-one oxime-O-benzoate, ethanone-1-[9- Ethyl-6-(2-methyl-4-tetrahydrofuranylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-(2-methyl- 4-Tetrahydropyranylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-(2-methyl-5-tetrahydrofuranylbenzoyl)-9H -carbazol-3-yl]-1-(O-acetyloxime), ethanone-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl }-9H-carbazol-3-yl]-1-(O-acetyloxime).

Examples of the acetophenone compound include α-aminoketone compounds and α-hydroxyketone compounds.
Examples of α-aminoketone compounds include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-( Examples thereof include 4-morpholin-4-yl-phenyl)-butan-1-one and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one.
Examples of α-hydroxyketone compounds include 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-(4-i-propylphenyl)-2-hydroxy-2-methylpropan-1-one , 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenylketone, 2-hydroxy-1-{4-[2-(2-hydroxyethoxy)ethoxy]phenyl }-2-methylpropan-1-one and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

Examples of biimidazole compounds include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2, 4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5, Examples include 5'-tetraphenyl-1,2'-biimidazole.

Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, lithium phenyl(2,4,6-trimethylbenzoyl) Examples include phosphinates.

Among these, the photopolymerization initiator is preferably an acetophenone compound from the viewpoint of affinity with the fibrous cellulose dispersion and solubility in developing solutions (particularly water and water-containing solvents). , α-hydroxyketone compounds are more preferred.

The content of the polymerization initiator relative to 100 parts by mass of the solid content of the radiation-sensitive component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less. It is.
When the content of the polymerization initiator is within the above range, it is possible to easily obtain a radiation-sensitive component that has excellent radiation sensitivity and exhibits negative radiation sensitivity even at a low exposure dose.

<Other ingredients>
In addition to the above-mentioned fibrous cellulose and radiation-sensitive components, the present scaffolding material may contain other components other than these.
Examples of the other components include hydrophilic polymers, wet paper strength agents, organic ions, crosslinking agents, surfactants, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, preservatives, and antifoaming agents. , organic particles, lubricants, antistatic agents, ultraviolet absorbers, dyes, pigments, stabilizers, magnetic powders, orientation promoters, plasticizers, and dispersants.
Each of these other components may be used alone or in combination of two or more.

[Hydrophilic polymer]
The present scaffolding material may contain one or more hydrophilic polymers.
The hydrophilic polymer refers to a polymer compound having a weight average molecular weight of 5,000 or more, which dissolves 1 g or more in 100 mL of ion-exchanged water at 25° C. under normal pressure.
Note that hydrophilic polymers include acid-decomposable groups and radically polymerizable groups whose solubility in solvents can be significantly changed by acids and radicals generated when a radiation-sensitive compound is irradiated with radiation. It is a hydrophilic polymer other than a polymer having .

The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (excluding the fibrous cellulose).
As the hydrophilic oxygen-containing organic compound, for example, a compound having an SP value of 9.0 or more is preferable.

The hydrophilic polymer is a compound other than the above polymerizable compound.
Examples of hydrophilic polymers include polyalkylene glycols (e.g. polyethylene glycol, polypropylene glycol), cellulose derivatives (e.g. hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, methylcellulose, carboxyethylcellulose, carboxymethylcellulose), casein, etc. Proteins, starches (e.g. dextrin, cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, amylose), polyvinyl alcohol, modified polyvinyl alcohol (e.g. acetoacetylated polyvinyl alcohol, ethylene-vinyl alcohol) Copolymers, ethylene oxide polyvinyl alcohol), polyalkylene oxides (e.g. polyethylene oxide), polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylates (e.g. sodium polyacrylate), polycations (e.g. polyacrylamide, polyethyleneimine) ), polyanions, zwitterionic polymers, acrylic acid alkyl ester copolymers, urethane copolymers, thickening polysaccharides (e.g. xanthan gum, guar gum, tamarind gum, locust bean gum, quince seed, alginic acid, metal alginate) salt, pullulan, carrageenan, sacran, pectin), polyester, modified polyester, modified polyimide, glycerin such as polyglycerin, hyaluronic acid, metal salts of hyaluronic acid, carboxyvinyl polymer, alkyl methacrylate, acrylic acid copolymer, polyacrylic acid salts (eg, sodium polyacrylate).
Among these, it is particularly preferable to use polyethylene glycol, polyethylene oxide, polyvinyl alcohol, and modified polyvinyl alcohol.

The weight average molecular weight of the hydrophilic polymer is not particularly limited as long as it is 5,000 or more, but it is preferably 10,000 from the viewpoint of shape stability of the scaffold material and enabling fine patterning. Above, it is more preferably 15,000 or more, still more preferably 20,000 or more, preferably 8 million or less, more preferably 5 million or less, still more preferably 1 million or less, particularly preferably 100,000 or less.
Note that the weight average molecular weight can be measured using, for example, GPC.

When the present scaffolding material contains a hydrophilic polymer, the content of the hydrophilic polymer in the present scaffolding material is determined such that the shape stability of the present scaffolding material and the ability to easily form a patterned hydrogel scaffolding material, etc. From this point of view, it is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 8% by mass or more, and preferably 60% by mass or less, more preferably 40% by mass or less, even more preferably 20% by mass or less. It is not more than 15% by mass, more preferably not more than 15% by mass.

[Wet paper strength enhancer]
The wet paper strength enhancer is an agent that suppresses the decline in paper strength when paper gets wet with water, and by adding it to pulp fibers that easily loosen when exposed to water, the wet paper strength enhancer is an agent that suppresses the decline in paper strength when paper gets wet with water. It has the effect of holding bonds, making them difficult to unravel, and increasing strength.

Examples of wet paper strength agents include polyamine polyamide epihalohydrin, melamine formaldehyde resin, and urea formaldehyde resin.
Polyamine polyamide epihalohydrin is synthesized, for example, by adding epichlorohydrin to a main chain obtained by condensing a polyhydric acid and a polyethylene polyamine. Polyamine polyamide epihalohydrin can be used in a wide pH range, and a high wet paper strength enhancing effect can be obtained with a small amount added.
Melamine formaldehyde resin is synthesized, for example, by adding formaldehyde to melamine, followed by acid condensation.
Urea-formaldehyde resin is synthesized, for example, by adding formaldehyde to urea and then crosslinking a portion of the resin.
Among these, it is preferable to use polyamine polyamide epihalohydrin because it has a low water absorption coefficient and linear thermal expansion coefficient, and the present scaffolding material with excellent transparency can be easily obtained. Among the polyamine polyamide epihalohydrins, polyamine polyamide epichlorohydrin is more preferred.

[Organic ions]
Examples of the organic ions include tetraalkylammonium ions and tetraalkylphosphonium ions.
Examples of the tetraalkylammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, and lauryl trimethyl. Examples include ammonium ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion, and tributylbenzylammonium ion.
Examples of the tetraalkylphosphonium ion include tetramethylphosphonium ion, tetraethylphosphonium ion, tetrapropylphosphonium ion, tetrabutylphosphonium ion, and lauryltrimethylphosphonium ion.

As the organic ion, a tetrapropylonium ion such as a tetra n-propylonium ion, a tetrabutylonium ion such as a tetra n-butylonium ion, etc. can also be used.

<Manufacturing method of this scaffolding material>
The present scaffolding material includes, for example, preparing an aqueous dispersion (slurry) containing fibrous cellulose and a radiation-sensitive component, and optionally containing the other components, and drying this slurry after placing it in a container. Alternatively, it can be obtained by forming this slurry into a sheet. Among these, the present scaffold material is preferably a cell culture scaffold sheet obtained by forming the slurry into a sheet.
In the present invention, there is no particular distinction between a sheet and a film, and the film (plate) shaped molded product is collectively referred to as a sheet.

By drying the slurry after placing it in a container, a scaffold material can be directly formed in a desired container, and a cell culture container can be directly obtained.
Examples of methods for placing the slurry in the container include methods using conventionally known devices such as syringes, droppers, and spatulas.
The container in which the slurry is placed is not particularly limited, but includes, for example, containers conventionally used for cell culture, such as cell culture plates, flasks, dishes, tubes, chamber slides, etc. It will be done.

The method of drying the slurry placed in the container is not particularly limited, but examples include methods of drying by heating with hot air, infrared rays, far infrared rays, or near infrared rays (heat drying method), methods of drying under vacuum (vacuum drying method) law). Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied.
The heating temperature in the heating drying method is not particularly limited, but is preferably 20°C or higher, more preferably 40°C or higher, preferably 150°C or lower, more preferably 120°C or lower, and still more preferably 100°C or lower.
By setting the heating temperature at or above the lower limit value, the dispersion medium can be quickly volatilized, and by setting the heating temperature at or below the upper limit value, it is possible to suppress the cost required for heating and prevent discoloration and side reactions of fibrous cellulose due to heat. Can be easily suppressed.

The method of forming the slurry into a sheet is not particularly limited, but may include a coating process in which the slurry is coated on a base material and dried to peel the formed sheet from the base material, or a process in which the slurry is formed into a paper sheet. A papermaking process in which Further, the sheet may be manufactured continuously by using a coating device and a belt-shaped base material. Among these, it is more preferable to manufacture the sheet by a coating process.

- Coating process The material of the base material used in the coating process is not particularly limited. From the viewpoint of suppressing shrinkage of the sheet during drying, etc., a base material with high wettability to the slurry is preferable, but a base material from which the formed sheet can be easily peeled off after drying is preferable.
The base material is preferably exemplified by a resin film or plate, or a metal film or plate, but is not particularly limited. Specific examples of the base material include films and plates of resins such as poly(meth)acrylic, polyethylene terephthalate, polyvinyl chloride, polystyrene, polypropylene, polycarbonate, and polyvinylidene chloride, aluminum, zinc, copper, iron, etc. Examples include metal films and plates, and those whose surfaces have been oxidized, stainless steel films and plates, and brass films and plates.

In the coating process, if the viscosity of the slurry is low and it spreads on the base material, in order to obtain a sheet with a predetermined thickness and basis weight, a damming frame is provided on the base material before applying the slurry. May be coated.
Although the frame for damming is not particularly limited, it is preferable to select a frame from which the edges of the attached sheet can be easily peeled off after drying, for example. From this point of view, frames made of resin or metal are more preferable, and specific examples include frames made of resin such as poly(meth)acrylic, polyethylene terephthalate, polyvinyl chloride, polystyrene, polypropylene, polycarbonate, and polyvinylidene chloride. Examples include frames made of metals such as aluminum, zinc, copper, and iron, and those whose surfaces have been oxidized, stainless steel frames, and brass frames.

The coating machine for coating the slurry on the base material is not particularly limited, and examples thereof include a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, and a spray coater. Among these, die coaters, curtain coaters, and spray coaters are particularly preferred because they can make the sheet thickness more uniform.

The temperature of the slurry and the coating atmosphere temperature when applying the slurry to the base material are not particularly limited, but are preferably 5°C or higher and 80°C or lower, more preferably 10°C or higher and 60°C or lower, and even more preferably 15°C or higher and 50°C or higher. The temperature is preferably 20°C or higher and 40°C or lower, particularly preferably 20°C or higher and 40°C or lower.
When these temperatures are above the lower limit, the slurry can be coated more easily, and when these temperatures are below the upper limit, volatilization of the dispersion medium during coating and side reactions due to heat can be easily suppressed.

The method of drying the slurry coated on the substrate is not particularly limited, and examples include a non-contact drying method, a method of drying while restraining the sheet, or a combination thereof.
Non-contact drying methods are not particularly limited, but include, for example, a method of drying by heating with hot air, infrared rays, far infrared rays, or near infrared rays (heat drying method), and a method of drying under vacuum (vacuum drying method). . Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Drying using infrared rays, far infrared rays, or near infrared rays is not particularly limited, and can be performed using, for example, an infrared device, a far infrared device, or a near infrared device.

The heating temperature in the heating drying method is not particularly limited, but is preferably 20°C or higher, more preferably 40°C or higher, preferably 150°C or lower, more preferably 120°C or lower, and still more preferably 100°C or lower.
By setting the heating temperature at or above the lower limit value, the dispersion medium can be quickly volatilized, and by setting the heating temperature at or below the upper limit value, it is possible to suppress the cost required for heating and prevent discoloration and side reactions of fibrous cellulose due to heat. Can be easily suppressed.

- Paper-making process The paper-making process is performed, for example, by making paper from the slurry using a paper machine. Further, in the paper making process, a known paper making method such as hand paper making may be employed.
The paper machine is not particularly limited, but examples thereof include continuous paper machines such as fourdrinier type, cylinder type, and inclined type, and multilayer paper machines combining these.

Specifically, the papermaking process can be carried out by filtering and dewatering the slurry to obtain a wet paper sheet, and then pressing and drying this sheet.
A filter cloth can be used when filtering and dewatering the slurry, and the filter cloth is not particularly limited, but may include, for example, fibrous cellulose, a radiation-sensitive component, and a hydrophilic resin used as necessary It is more preferable to use a filter cloth that does not allow other components to pass through and that does not slow down the filtration rate too much. Such filter cloth is not particularly limited, but for example, sheets, fabrics, and porous membranes made of organic polymers are preferable.
The organic polymer is not particularly limited, but non-cellulose organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferred.
Specific examples of the filter cloth include a porous membrane of polytetrafluoroethylene with a pore size of 0.1 μm or more and 20 μm or less, and a polyethylene terephthalate or polyethylene fabric with a pore size of 0.1 μm or more and 20 μm or less.

In the papermaking process, the method for producing a sheet from the slurry includes, for example, discharging the slurry onto the upper surface of an endless belt, squeezing the dispersion medium from the discharged slurry to produce a web, and a water squeezing section that generates a web. It can be carried out using a manufacturing apparatus equipped with a drying section that dries the sheet to produce a sheet. In one aspect of this case, an endless belt is disposed from the water squeezing section to the drying section, and the web produced in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

The dewatering method in the papermaking process is not particularly limited, but includes, for example, dehydration methods commonly used in paper manufacturing. Among these, a method of dewatering using a fourdrinier, a cylinder screen, an inclined wire, or the like, and then further dewatering using a roll press is preferable.
Further, the drying method in the papermaking process is not particularly limited, but includes, for example, a drying method commonly used in paper manufacturing. Among these, drying methods using a cylinder dryer, Yankee dryer, hot air drying, near-infrared heater, infrared heater, etc. are more preferred.

<Characteristics of this scaffolding material>
The thickness of the present scaffolding material, particularly the thickness of the sheet-like present scaffolding material, is preferably 10 μm or more from the viewpoints of shape stability of the scaffolding material and ease of forming a patterned hydrogel scaffolding material. , more preferably 20 μm or more, still more preferably 25 μm or more, preferably 1,000 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less.
The amount placed in the container, the amount of coating, the amount of paper to be made, etc. may be adjusted as appropriate so that the thickness of the scaffolding material falls within the above range.

The present scaffold material preferably has excellent light transmittance, and has a total light transmittance of preferably 70% or more, more preferably 80% or more, and still more preferably 90% or more. The upper limit of the total light transmittance is not particularly limited, and the higher it is, the more preferable it is, and it may be 100%, but from the viewpoint of ease of manufacture, etc., it is preferably 99.5% or less.
The total light transmittance is measured using a haze meter in accordance with JIS K 7361-1:1997.

Further, the present scaffolding material preferably has excellent transparency, and has a haze of preferably 10% or less, more preferably 3% or less, and still more preferably 2% or less. The lower limit of the haze is not particularly limited, and the lower the haze is, the more preferable it is, and it may be 0%, but from the viewpoint of ease of production, etc., it is preferably 0.1% or more.
Haze is measured using a haze meter in accordance with JIS K 7136:2000.

≪Patterned hydrogel scaffold material≫
The patterned hydrogel scaffold material is a scaffold material for cell culture that has a hydrogel pattern and is obtained by developing the present scaffold material.
The patterned hydrogel scaffold material allows the hydrogel pattern portion to be used as a cell culture scaffold during cell culture, and has excellent transparency, making it easy to observe the state of cell assembly and cell clusters. Therefore, it is thought that it can be suitably used in cell culture containers (including cell culture instruments and cell culture devices).

One embodiment of the patterned hydrogel scaffold material includes an exposed area where the scaffold material is exposed and cured, and a hydrogel pattern area (unexposed area) where the radiation-sensitive component is developed without being cured and becomes a hydrogel. The exposed area cannot serve as a scaffold for cells, and only the hydrogel pattern area in the unexposed area serves as a scaffold, allowing cells to selectively aggregate and culture cells (manufacturing cell clusters). .

The exposed portion is composed of a cured product of a radiation-sensitive component containing cellulose.
From the viewpoint of controlling the structure of the cell tissue, it is preferable that the exposed area has a so-called hard structure, which has lower mechanical flexibility than the hydrogel pattern area.

The hydrogel pattern area is composed of cellulose and water retained by the cellulose. The hydrogel pattern region preferably has appropriate mechanical flexibility in order to provide a scaffold for cell culture.

The shape of the hydrogel pattern is not particularly limited, and examples thereof include a circular shape, an elliptical shape, a polygonal shape, and a line shape.
The width of the hydrogel pattern is usually 0.1 μm to 1 mm, preferably 0.1 to 750 μm, more preferably 0.1 to 500 μm.
By adjusting the width etc. of the hydrogel pattern, the size of the formed spheres (cell clusters) etc. can be controlled.

Specifically, the patterned hydrogel scaffold material is produced by irradiating a portion of the scaffold material with radiation, and removing the radiation-sensitive component in the unexposed area with at least one developer selected from water and a water-containing solvent. It can be manufactured by a method including a step of washing and removing (developing) to form a hydrogel pattern. This manufacturing method can also be said to be a method for manufacturing a hydrogel pattern.
Note that after irradiation with radiation, a baking (PEB) step may be performed if necessary.
Further, the pattern formed after development may be rinsed (cleaned) with a rinsing liquid.

For radiation irradiation, at least a portion of the scaffold material is selectively irradiated with radiation, usually via a photomask or the like, using, for example, a contact aligner, a stepper, or a scanner.

The light source for exposure is not particularly limited, but for example, known light sources such as a high-pressure mercury lamp, a metal halide lamp, an ultra-high-pressure mercury lamp, a KrF excimer laser, an ArF excimer laser, an EUV irradiation device, a soft X-ray irradiation device, an electron drawing device, etc. can be used. Can be used.
Among the radiations, radiation with a wavelength of 313 nm or more is preferable, and radiation containing ultraviolet rays with a wavelength of 365 nm is particularly preferable. Therefore, as an exposure light source, high-pressure mercury that can irradiate radiation with a wavelength of 313 nm or more including ultraviolet rays of 365 nm is preferable. More preferred are lamps, metal halide lamps, and ultra-high pressure mercury lamps. By using these exposure light sources, relatively high transmittance can be obtained in the wavelength region of 313 nm or more, even for scaffolding materials with a thickness of 10 μm or more, and the back side of the scaffolding material can be sufficiently exposed without reducing the light intensity. can be done.

The exposure amount during radiation irradiation can be determined by measuring the intensity of the radiation at a wavelength of 365 nm using a luminometer (OAI model 356, manufactured by OAI Optical Associates Inc.). The exposure amount is preferably 10 mJ/cm ² or more and 1,000 mJ/cm ² or less, more preferably 100 mJ/cm ² or more and 800 mJ/cm ² or less.

Examples of the developing method include a shower developing method, a spray developing method, an immersion developing method, and a paddle developing method.
Development conditions are not particularly limited, and are usually at 20 to 40°C for about 1 to 10 minutes.

As the developer, at least one selected from water and a water-containing solvent can be used. Among these, water is preferred, and pure water is more preferred.

Examples of the water-containing solvent include a mixed solvent of water and a water-miscible organic solvent, and among these, a mixed solvent of water and a water-miscible alcohol is preferred.

Examples of the water-miscible organic solvent include monohydric alcohols (e.g., methanol, ethanol, 1-propanol, isopropyl alcohol (IPA), t-butanol, 1-methoxy-2-propanol (PGME)), Alcohols such as alcohols (e.g. ethylene glycol, glycerin); Ketones such as acetone; Ethers such as tetrahydrofuran; Esters such as ethyl acetate, methyl acetate; N,N-dimethylformamide, N,N-dimethylacetamide, Examples include amides such as N-methylpyrrolidone; sulfoxides such as dimethyl sulfoxide. Among these, ethanol, IPA, and PGME are preferred.
These organic solvents may be used alone or in combination of two or more.

The content of the organic solvent in the mixed solvent is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 99% by mass or more.
Note that the mixed solvent may contain, for example, silicone oil as a component other than water and the organic solvent.

As the developer, at least one selected from water and a water-containing solvent, and one or more alkaline developers may be used depending on the type of radiation-sensitive component.
Examples of the alkaline developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, and methyldiethylamine. , ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4 Examples include aqueous alkaline solutions in which at least one alkaline compound such as [.3.0]-5-nonene is dissolved. As the alkaline developer, a TMAH aqueous solution is preferred.
The concentration of the alkaline developer is preferably 0.1% by mass or more and 2.38% by mass or less, more preferably 0.4% by mass or less and 2.38% by mass or less.

<<Method for producing cultured cells and method for producing spheres>>
The method for producing cultured cells and the method for producing spheres (cell aggregates) according to the present invention includes a step of culturing cells on the present scaffold material, and includes a step of culturing cells on a patterned hydrogel scaffold material. It is preferable.
When culturing cells on a patterned hydrogel scaffold, cells are selectively cultured in the hydrogel part (unexposed part) of the scaffold (the exposed part does not serve as a scaffold for cells), and Preferably, agglomerates are formed. In this case, cells seeded on the scaffold can be three-dimensionally bonded on the surface of the hydrogel part as a scaffold to form a cell cluster, without having to suspend the cell cluster in the culture medium. , cells can be cultured for a long period of time while the hydrogel portion is stably maintained attached to the scaffold.

The cells are preferably those that form bonds with each other, and the animal species, organ/tissue types, etc. are not particularly limited.
Examples of the cells include anchorage-dependent cells, and specific examples include liver, pancreas, kidney, nerve, skin, bone marrow, etc. derived from animals such as humans, pigs, dogs, rats, and mice. Examples include primary cells and established cell lines, and more specifically include cancer cells such as HepG2 cells, HeLa cells, and F9 cells, and normal cells. More specific examples include fibroblasts such as 3T3 cells; stem cells such as ES cells, iPS cells, and mesenchymal stem cells (e.g. UE7T-13 cells); renal cells such as HEK293 cells; nerve cells such as NT2 cells. ; endothelial cells such as UV♀2 cells and HMEC-1 cells; cardiomyocytes such as H9c2 cells; epithelial cells such as Caco-2 cells; or cells obtained by genetically manipulating these cells. In addition, floating cells such as blood cells such as white blood cells, red blood cells, and platelets may also be used.
One type of the above-mentioned cells may be used alone, or two or more types may be used.

When seeding cells, a culture solution containing cells may be used.
As the culture solution, an aqueous solution containing necessary salts and/or nutritional components at appropriate concentrations can be used so as to maintain the survival state and function of the cells.

≪Cell culture container≫
The cell culture container according to the present invention is a container that includes the hydrogel pattern in at least a portion of the cell culture area, and is preferably formed using the patterned hydrogel scaffold material.
Specifically, the cell culture container can be formed by placing the patterned hydrogel scaffold in a conventionally known cell culture container.

In another embodiment of the cell culture container, for example, by placing the slurry described in the column of the method for manufacturing the scaffold material in the container and then performing the drying, exposure, and development, patterned hydrocarbons can be directly deposited into the container. Also included are cell culture containers formed with gel scaffolds.

EXAMPLES The features of the present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

[Method for measuring average fiber width of fine fibrous cellulose]
The supernatant liquid of the fine fibrous cellulose dispersion was diluted with water so that the concentration of fine fibrous cellulose was 0.01% by mass or more and 0.1% by mass or less, and the diluted solution was dropped onto a hydrophilic carbon grid membrane. After drying the dropped liquid, it was stained with uranyl acetate, and the fiber width of the fine fibrous cellulose was observed using a transmission electron microscope (manufactured by JEOL Ltd., JEOL-2000EX). Furthermore, the average fiber width of the fine fibrous cellulose was calculated from the obtained image as described above.
Note that the fiber width refers to the length in the direction perpendicular to the fiber length direction of the fine fibrous cellulose, as observed in a transmission electron micrograph.

[Measurement of the amount of phosphorus oxoacid groups in fine fibrous cellulose]
The amount of phosphorus oxo acid groups in the fine fibrous cellulose is determined by the fine fiber prepared by diluting the target fine fibrous cellulose dispersion with ion-exchanged water so that the fine fibrous cellulose content is 0.2% by mass. The measurement was performed by treating a cellulose-containing slurry with an ion exchange resin and then titrating with an alkali.
For the treatment with the ion exchange resin, 1/10 of the volume of a strongly acidic ion exchange resin (manufactured by Organo Co., Ltd., Amber Jet 1024, conditioned) was added to the fine fibrous cellulose-containing slurry, and the mixture was shaken for 1 hour. After that, the slurry was poured onto a mesh having an opening of 90 μm to separate the ion exchange resin and the slurry.
In addition, titration using the alkali is performed by adding 10 μL of a 0.1N aqueous sodium hydroxide solution every 5 seconds to the fine fibrous cellulose-containing slurry after treatment with an ion exchange resin, while changing the pH value of the slurry. This was done by measuring. Note that the titration was performed while blowing nitrogen gas into the slurry 15 minutes before the start of the titration.

In this neutralization titration, on a curve plotting the measured pH against the amount of sodium hydroxide added, two points are observed where the increment (differential value of pH with respect to the amount of sodium hydroxide dropped) becomes maximum. Among these, the maximum point of increment obtained first after starting to add sodium hydroxide is called the first end point, and the maximum point of increment obtained next is called the second end point (FIG. 1). The amount of sodium hydroxide required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of sodium hydroxide required from the start of titration to the second end point is equal to the total amount of dissociated acid in the slurry used for titration. The amount of sodium hydroxide (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated was defined as the amount of phosphorus oxoacid group (mmol/g).

[Measurement of the amount of sulfate groups in fine fibrous cellulose]
After the obtained fine fibrous cellulose was wet-ashed using perchloric acid and concentrated nitric acid, it was diluted at an appropriate ratio and the amount of sulfur was measured by ICP emission spectrometry.
The value obtained by dividing this amount of sulfur by the absolute dry mass of the fine fibrous cellulose tested was defined as the amount of sulfuric acid groups (unit: mmol/g).

[Measurement of carboxy group content of fine fibrous cellulose]
The amount of carboxy groups in the fine fibrous cellulose was determined by adding 50 μL of a 0.1N sodium hydroxide aqueous solution once every 30 seconds to the fine fibrous cellulose-containing slurry treated with the ion exchange resin. The measurement was carried out in the same manner as the measurement of the base amount.
The amount of carboxy group (mmol/g) is determined by calculating the amount of sodium hydroxide (mmol) required in the region corresponding to the first region from the start of titration to the first end point in the slurry to be titrated. Calculated by dividing by the solid content (g).
As shown in Figure 2, the first end point is defined as one observed increment (differential of pH with respect to the amount of sodium hydroxide added) in a curve plotting the measured pH against the amount of added sodium hydroxide. This is the point where the value) is maximum.

<Production Example 1> Production of fine fibrous cellulose dispersion (1) As the raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245g/m ² , sheet form, disintegrated and JIS A Canadian Standard Freeness (CSF) of 700 ml measured according to P 8121-2:2012 was used.
This raw material pulp was subjected to phosphorus oxo oxidation treatment as follows.
First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolutely dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. A pulp impregnated with a chemical solution was obtained. Next, the resulting chemical solution-impregnated pulp was heated for 250 seconds in a hot air dryer at 165° C. to introduce phosphorus oxo acid groups into cellulose in the pulp, thereby obtaining phosphorus oxo-oxidized pulp 1.

Next, the obtained phosphorus oxo-oxidized pulp 1 was subjected to a washing treatment.
The washing process involves repeating an operation in which a pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorus oxo-oxidized pulp is stirred so that the pulp is uniformly dispersed, and then filtered and dehydrated. This was done by The washing end point was reached when the electrical conductivity of the filtrate became 100 μS/cm or less.

Next, the washed phosphorus oxo-oxidized pulp was neutralized as follows.
First, after diluting the washed phosphorus oxo-oxidized pulp with 10 L of ion exchange water, a 1N sodium hydroxide aqueous solution was added little by little while stirring to obtain a phosphorus oxo-oxidized pulp slurry with a pH of 12 to 13. . Next, the phosphorus oxo-oxidized pulp slurry was dehydrated to obtain a neutralized phosphorus oxo-oxidized pulp. Next, the phosphorus oxo-oxidized pulp after the neutralization treatment was subjected to the same treatment as the washing treatment described above to obtain phosphorus oxo-oxidized pulp A.

The infrared absorption spectrum of the obtained phosphorus oxo-oxidized pulp A was measured using FT-IR. As a result, absorption based on P=O of phosphoric acid groups was observed near 1230 cm ⁻¹ , confirming that phosphoric acid groups were added to the pulp.

In addition, when the obtained phosphorus oxo-oxidized pulp A was analyzed using an X-ray diffraction device, two typical positions were found: around 2θ = 14° to 17° and around 2θ = 22° to 23°. A typical peak was confirmed, and it was confirmed that the phosphorus oxo-oxidized pulp A had a cellulose type I crystal structure.

Ion-exchanged water was added to the obtained phosphorus oxo-oxidized pulp A to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated twice at a pressure of 200 MPa with a wet atomizer (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a fine fibrous cellulose dispersion (1) containing fine fibrous cellulose.

It was confirmed by X-ray diffraction that this fine fibrous cellulose maintained a cellulose I type crystal structure.
Further, the average fiber width of the fine fibrous cellulose was 4 nm.
The amount of phosphorus oxo acid groups (first amount of dissociated acids) of the fine fibrous cellulose was 1.45 mmol/g, and the total amount of dissociated acids was 2.45 mmol/g.

<Production Example 2> Production of fine fibrous cellulose dispersion (2) Using phosphorous acid (phosphonic acid) instead of ammonium dihydrogen phosphate, the phosphorous acid (phosphonic acid) in the chemical solution impregnated pulp was 33 parts by mass. The same operation as in Production Example 1 was performed except that the following procedure was performed to obtain phosphorus oxo-oxidized pulp B and fine fibrous cellulose dispersion (2).

The infrared absorption spectrum of the obtained phosphorus oxo-oxidized pulp B was measured using FT-IR. As a result, an absorption based on P=O of a phosphonic acid group, which is a tautomer of a phosphorous acid group, was observed near 1210 cm ^-1 , indicating that a (phosphorous acid group) was added to the pulp. It was confirmed that there is.

In addition, when the obtained phosphorus oxo-oxidized pulp B was analyzed using an X-ray diffraction device, two typical positions were found, around 2θ = 14° to 17° and around 2θ = 22° to 23°. A typical peak was confirmed, and it was confirmed that the phosphorus oxo-oxidized pulp B had a cellulose type I crystal structure.

It was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained a cellulose I type crystal structure.
Further, the average fiber width of the fine fibrous cellulose was 4 nm.
Regarding the fine fibrous cellulose, the amount of phosphorous acid groups introduced into the cellulose (first amount of dissociated acids) and the total amount of dissociated acids were 1.51 mmol/g and 1.54 mmol/g, respectively.

<Production Example 3> Production of fine fibrous cellulose dispersion (3) Amidosulfuric acid was used instead of ammonium dihydrogen phosphate so that the amount of amidosulfuric acid in the chemical solution-impregnated pulp was 38 parts by mass, and the mixture was dried in a hot air dryer. A sulfated pulp and a fine fibrous cellulose dispersion (3) were obtained by performing the same operation as in Production Example 1 except that the heating time was 19 minutes.

The infrared absorption spectrum of the obtained sulfated pulp was measured using FT-IR. As a result, absorption based on sulfate groups, which are substituents derived from sulfur oxoacid groups, was observed around 1220 to 1260 cm ⁻¹ , confirming that sulfate groups were added to the pulp.

In addition, when the obtained sulfated pulp was sampled and analyzed using an X-ray diffraction device, two typical positions were observed: around 2θ = 14° to 17° and around 2θ = 22° to 23°. A typical peak was confirmed, and it was confirmed that the sulfated pulp had a cellulose type I crystal structure.

It was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained a cellulose I type crystal structure.
Further, the average fiber width of the fine fibrous cellulose was 4 nm.
Regarding the fine fibrous cellulose, the amount of sulfate groups introduced into the cellulose was 1.12 mmol/g.

<Production Example 4> Production of fine fibrous cellulose dispersion (4) As the raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245g/m ² , sheet form, disintegrated and JIS A Canadian Standard Freeness (CSF) of 700 ml measured according to P 8121-2:2012 was used. This raw material pulp was subjected to alkaline TEMPO oxidation treatment as follows.
First, 100 parts by mass (absolutely dry mass) of the raw material pulp, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), and 10 parts by mass of sodium bromide were added to water. It was dispersed in 10,000 parts by mass. Next, 13 parts by mass of an aqueous sodium hypochlorite solution was added in an amount of 3.8 mmol per 1.0 g of pulp to start the reaction. During the reaction, a 0.5M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 or more and 10.5 or less, and the reaction was considered complete when no change in pH was observed.

Next, the obtained TEMPO-oxidized pulp was subjected to a washing treatment to obtain a TEMPO-oxidized pulp.
In the cleaning process, the pulp slurry after TEMPO oxidation is dehydrated to obtain a dehydrated sheet, then 5,000 parts by mass of ion-exchanged water is poured in, stirred to uniformly disperse the pulp, and then filtered and dehydrated. This was done by repeating. The washing end point was reached when the electrical conductivity of the filtrate became 100 μS/cm or less.

When the obtained TEMPO oxidized pulp was analyzed using an X-ray diffraction device, typical peaks were found at two positions: around 2θ = 14° to 17° and around 2θ = 22° to 23°. was confirmed, and it was confirmed that the TEMPO oxidized pulp had a cellulose I type crystal structure.

Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated twice at a pressure of 200 MPa with a wet atomizer (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a fine fibrous cellulose dispersion (4) containing fine fibrous cellulose.

It was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained a cellulose I type crystal structure.
Further, the average fiber width of the fine fibrous cellulose was 4 nm.
Regarding the fine fibrous cellulose, the amount of carboxy groups introduced into the cellulose was 1.30 mmol/g.

<Production Example 5> Production of fine fibrous cellulose dispersion (5) As the raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245g/m ² , sheet form, disintegrated and JIS A Canadian Standard Freeness (CSF) of 700 ml measured according to P 8121-2:2012 was used.
This pulp was refined in a double disc refiner until the irregular freeness reached 100 ml to obtain a pulp dispersion having a concentration of 2% by mass. This pulp dispersion was diluted with ion-exchanged water to a concentration of 0.7% by mass, and treated three times at a pressure of 120 MPa with a high-pressure homogenizer (manufactured by NiroSoavi, Panda Plus 2000) to obtain a solution containing fine fibrous cellulose. A fine fibrous cellulose dispersion (5) was obtained.

It was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained a cellulose I type crystal structure.
Further, the average fiber width of the fine fibrous cellulose was 130 nm.

<Production Example 6> Production of solution of radiation-sensitive component (1) N,N'-{[(2-acrylamido-2-[(3-acrylamidopropoxy)methyl]propane-1,3-diyl)bis(oxy )]bis(propane-1,3-diyl)}diacrylamide (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., FOM-03006) 1.0 parts by mass and 2-hydroxy-4'-(2-hydroxyethoxy)- and 0.1 part by mass of 2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd.), and pure water was added to dissolve the mixture so that the concentration of the mixture was 0.5% by mass. Thereafter, a solution (filtrate) of the radiation-sensitive component (1) was prepared by filtering through a Millipore filter with a pore size of 0.5 μm.
Note that 1 g or more of the radiation-sensitive component (1) in the obtained solution of the radiation-sensitive component (1) was dissolved in 100 g of water at 25° C. under atmospheric pressure.

<Production Example 7> Production of solution of radiation-sensitive component (2) 1.0 parts by mass of dipentaerythritol hexaacrylate (DPHA) (manufactured by Shin Nakamura Chemical Co., Ltd., NK Ester A-DPH) and 2-hydroxy-4 '-(2-hydroxyethoxy)-2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.1 part by mass, and 1-methoxy -2-Propanol was added and dissolved. Thereafter, a solution (filtrate) of the radiation-sensitive component (2) was prepared by filtering through a Millipore filter with a pore size of 0.5 μm.
Note that 1 g or more of the radiation-sensitive component (2) in the obtained solution of the radiation-sensitive component (2) was dissolved in 100 g of water at 25° C. under atmospheric pressure.

<Production Example 8> Production of a solution of radiation-sensitive component (3) 1.0 parts by mass of fluorene-based acrylate (manufactured by Osaka Gas Chemical Co., Ltd., EA-0300) and 2-hydroxy-4'-(2-hydroxyethoxy) )-2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) and 0.1 part by mass, 1-methoxy-2-propanyl acetate was added so that the concentration of the mixture was 0.5% by mass. and dissolved. Thereafter, a solution (filtrate) of the radiation-sensitive component (3) was prepared by filtering through a Millipore filter with a pore size of 0.5 μm.
Note that the radiation-sensitive component (3) in the obtained solution of radiation-sensitive component (3) includes 100 g of water, 100 g of alcohol having 1 to 6 carbon atoms, and water and alcohol having 1 to 6 carbon atoms. At 25° C. and atmospheric pressure, no more than 1 g was dissolved in any of the 100 g of the mixed solvent.

<Example 1>
Ion-exchanged water was added to a fine fibrous cellulose dispersion (1) having a solid content concentration of 2.0% by mass to obtain a fine fibrous cellulose dispersion (A) having a solid content concentration of 0.5% by mass.
The fine fibrous cellulose dispersion (A) was adjusted so that the solid content in the solution of the radiation-sensitive component (1) was 20 parts by mass relative to 100 parts by mass of the solid content in the obtained fine fibrous cellulose dispersion (A). A) and a solution of the radiation-sensitive component (1) were mixed and stirred to prepare a solution of a negative-tone radiation-sensitive composition.

Next, a solution of the negative radiation-sensitive composition prepared so that the finished basis weight of the obtained radiation-sensitive sheet would be 65 g/m ² was weighed, spread on a commercially available acrylic plate, and heated at 50°C. It was dried in a dryer for 24 hours. In addition, a dam plate of 150 mm square was placed on the acrylic plate so as to have a predetermined basis weight. A radiation-sensitive sheet was obtained by the above procedure.
The thickness of the obtained radiation-sensitive sheet was 50 μm.

<Example 2>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) were mixed so that the solid content in the solution of the radiation-sensitive component (1) was 60 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Example 3>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) are mixed so that the solid content in the solution of the radiation-sensitive component (1) is 100 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Example 4>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) were mixed so that the solid content in the solution of the radiation-sensitive component (1) was 140 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Example 5>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) were mixed so that the solid content in the solution of the radiation-sensitive component (1) was 180 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Example 6>
Ion-exchanged water was added to the fine fibrous cellulose dispersion (2) with a solid content concentration of 2.0% by mass to obtain a fine fibrous cellulose dispersion (B) with a solid content concentration of 0.5% by mass.
The fine fibrous cellulose dispersion (B) was adjusted so that the solid content in the solution of the radiation-sensitive component (1) was 100 parts by mass relative to 100 parts by mass of the solid content in the obtained fine fibrous cellulose dispersion (B). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that B) and a solution of radiation-sensitive component (1) were mixed and stirred to prepare a solution of a negative-working radiation-sensitive composition.

<Example 7>
Ion-exchanged water was added to the fine fibrous cellulose dispersion (3) with a solid content concentration of 2.0% by mass to obtain a fine fibrous cellulose dispersion (C) with a solid content concentration of 0.5% by mass.
The fine fibrous cellulose dispersion (C) was adjusted so that the solid content in the solution of the radiation-sensitive component (1) was 100 parts by mass relative to 100 parts by mass of the solid content in the obtained fine fibrous cellulose dispersion (C). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that C) and a solution of the radiation-sensitive component (1) were mixed and stirred to prepare a solution of a negative radiation-sensitive composition.

<Example 8>
Ion-exchanged water was added to the fine fibrous cellulose dispersion (4) with a solid content concentration of 2.0% by mass to obtain a fine fibrous cellulose dispersion (D) with a solid content concentration of 0.5% by mass.
The fine fibrous cellulose dispersion (D) was adjusted so that the solid content in the solution of the radiation-sensitive component (1) was 100 parts by mass relative to 100 parts by mass of the solid content in the obtained fine fibrous cellulose dispersion (D). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that D) and the solution of the radiation-sensitive component (1) were mixed and stirred to prepare a solution of the negative-working radiation-sensitive composition.

<Example 9>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) are mixed so that the solid content in the solution of the radiation-sensitive component (2) is 100 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of a negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (2).

<Comparative example 1>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) are mixed so that the solid content in the solution of the radiation-sensitive component (1) is 10 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Comparative example 2>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) were mixed so that the solid content in the solution of the radiation-sensitive component (1) was 220 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that a solution of the negative radiation-sensitive composition was prepared by mixing and stirring the solution of the radiation-sensitive component (1).

<Comparative example 3>
Ion-exchanged water was added to the fine fibrous cellulose dispersion (5) with a solid content concentration of 2.0% by mass to obtain a fine fibrous cellulose dispersion (E) with a solid content concentration of 0.5% by mass.
The fine fibrous cellulose dispersion (E) was adjusted so that the solid content in the solution of the radiation-sensitive component (1) was 100 parts by mass relative to 100 parts by mass of the solid content in the obtained fine fibrous cellulose dispersion (E). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that E) and a solution of radiation-sensitive component (1) were mixed and stirred to prepare a solution of a negative-working radiation-sensitive composition.

<Comparative example 4>
The fine fibrous cellulose dispersion (A) and the fine fibrous cellulose dispersion (A) were mixed so that the solid content in the solution of the radiation-sensitive component (3) was 100 parts by mass relative to 100 parts by mass of the solid content in the fine fibrous cellulose dispersion (A). A radiation-sensitive sheet was obtained in the same manner as in Example 1, except that the solution of the radiation-sensitive component (3) was mixed and stirred to prepare a solution of the negative radiation-sensitive composition.

[Sheet haze]
The haze of the obtained radiation-sensitive sheet (radiation-sensitive sheet before exposure below) was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute Co., Ltd.) in accordance with JIS K 7136:2000. .
It can be said that the lower the haze of the obtained radiation-sensitive sheet, the better the visibility of cells by microscopic observation when cells are cultured using the sheet. In fact, when cells were cultured using a sheet, it was easy to see the cells under a microscope when the haze of the sheet was 10% or less, but when the haze of the sheet exceeded 10%, It became difficult to visually recognize cells by microscopic observation. The results are shown in Table 1.

[Sheet curability in exposed area]
A radiation-sensitive sheet was placed in an exposure device (manufactured by Eye Graphics Co., Ltd., model number: Eye Grandage ECS-4011GX/N, wavelength 200 to 450 nm) equipped with a metal halide lamp. Next, a photomask (manufactured by Toppan Printing Co., Ltd., made of synthetic quartz, L/S = 400 μm/400 μm) was placed on the sheet. At this time, a shim tape (manufactured by Misumi Group Inc., thickness 500 μm, made of SUS) was used so that the gap between the radiation-sensitive sheet and the photomask was 500 μm.
Next, the intensity of the radiation at a wavelength of 365 nm was set to 500 mJ/cm ² using an illuminance meter (OAI model 356, manufactured by OAI Optical Associates Inc.), and then exposed using an exposure device.
Next, the exposed sheet was dipped in pure water for 3 minutes and developed.

After development, the curability of the sheet in the exposed area was evaluated as follows. The results are shown in Table 1.
If the sheet surface in the exposed area after development is smooth and does not feel tacky, it is judged as having good curability and evaluated as "A". When the sheet surface is not gel-like, it is judged to have usable curability and evaluated as "B", and when the sheet surface in the exposed area after development is gel-like and not cured. , it was judged that the curing property was poor and was evaluated as "C".

[Gel pattern formation state in unexposed area]
A radiation-sensitive sheet was placed in an exposure device (manufactured by Eye Graphics Co., Ltd., model number: Eye Grandage ECS-4011GX/N, wavelength 200 to 450 nm) equipped with a metal halide lamp. Next, a photomask (manufactured by Toppan Printing Co., Ltd., made of synthetic quartz, L/S = 400 μm/400 μm) was placed on the sheet. At this time, a shim tape (manufactured by Misumi Group Inc., thickness 500 μm, made of SUS) was used so that the gap between the radiation-sensitive sheet and the photomask was 500 μm.
Next, the intensity of the radiation at a wavelength of 365 nm was set to 500 mJ/cm ² using an illuminance meter (OAI model 356, manufactured by OAI Optical Associates Inc.), and then exposed using an exposure device.
Next, the exposed sheet was dipped in pure water for 3 minutes and developed.

After development, the state of gel pattern formation in the unexposed areas of the sheet was evaluated as follows. The results are shown in Table 1.
If the sheet surface of the unexposed area after development becomes gel-like, it is judged that a gel pattern has been well formed in the unexposed area and is evaluated as "A". When comparing the sheet surface of the exposed area and a slight gel state is observed in the unexposed area, it is judged that a usable gel pattern has been formed in the unexposed area and evaluated as "B", After development, the surface of the sheet in the unexposed areas becomes gel-like, but the sheet collapses and becomes unusable, or the sheet does not collapse, but both the exposed and unexposed areas become gel-like, and the gel pattern is Cases in which no results were obtained were judged to be unusable and rated as "C".

[Cell cluster formation and cell cluster visibility]
UE7T-13 cells (JCRB1154), which are human bone marrow-derived mesenchymal stem cells (hMSCs), were cultured using 10% FBS (manufactured by GE Healthcare), 100 U/mL penicillin, and 100 μg/mL streptomycin (Thermo Fisher Scientific). Dulbecco's modified Eagle medium (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) containing Dulbecco's modified Eagle medium (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used. The cells were maintained by adhesion culture using a cell culture flask (manufactured by Thermo Fisher Scientific) in an environment of 37° C. and 5% CO ₂ concentration. When using cells for experiments, use TrypLETM Express (manufactured by Thermo Fisher Scientific) to detach cells in the logarithmic growth phase, and then suspend the cells in a medium to prepare a single cell suspension. did.

A developed sheet (a 50 μm thick sheet with a gel pattern formed thereon) obtained by the same method as the sheet curing of the exposed area was fractionated using a silicon chamber (flexiPERM micro) manufactured by Sarstad. UE7T-13 cells were seeded at 2.1×10 ⁴ cells/cm ² on a culture container and cultured at 37° C. for 3 days in an atmosphere with a CO ₂ concentration of 5%.

Formation of cell clusters was evaluated as follows. The evaluation results are shown in Table 1.
Three days after seeding the UE7T-13 cells, the collection of cells on the gel pattern was observed in bright field using an optical microscope (IX71, manufactured by Olympus Corporation). The case where cell clusters were present on the gel pattern in all three arbitrarily selected observation fields was evaluated as "A", and the case where cell clusters were present on the gel pattern in one or two of the three arbitrarily selected observation fields was evaluated as "A". The case where cell clusters were present was evaluated as "B", and the case where cell clusters were not present on the gel pattern in any of the three arbitrarily selected observation fields, or the visibility of the sheet was poor and the cell clusters were evaluated as "B". The case where it could not be visually recognized was evaluated as "C".

According to the results of Examples and Comparative Examples, the sheets shown in Examples 1 to 9 all had a low haze of 10% or less, and were sheets with excellent cell visibility. Further, the curability of the exposed area was good, and the gel pattern formation state of the unexposed area was also good. In addition, formation of cell clusters from cells seeded on the developed sheet (sheet on which a gel pattern was formed) was also good.

On the other hand, although the radiation-sensitive sheet obtained in Comparative Example 1 had a good haze of 10% or less, the content of radiation-sensitive components in the sheet was low and the content of cellulose was relatively high. Therefore, the curing properties of the exposed areas were poor and gelatinized, making it impossible to distinguish them from the unexposed areas, making it impossible to form a gel pattern in the unexposed areas. Cells aggregate along the gel pattern to form cell clusters, but if the entire surface of the sheet was gel-like, the cells could not aggregate well, resulting in poor cell cluster formation.

In addition, although the radiation-sensitive sheet obtained in Comparative Example 2 had a good haze of 10% or less, the content of radioactive components in the sheet was high and the content of cellulose was relatively low. Although the curability of the sheet was good in the unexposed area, the gel density in the unexposed area decreased, making it impossible to form a gel pattern well, and the sheet in the unexposed area collapsed. For this reason, it was not possible to observe the formation of cell clusters on the sheet.

Since the radiation-sensitive sheet obtained in Comparative Example 3 had a large average fiber width of cellulose, the sheet was significantly whitened due to scattering of transmitted light and the haze increased. For this reason, although the curability of the exposed area and the formation of a gel pattern in the unexposed area were good, the visibility of the cell clusters decreased, making it difficult to confirm the formation of the cell clusters.

The radiation-sensitive sheet obtained in Comparative Example 4 had an increased haze because it used a radiation-sensitive component that does not dissolve in water, alcohol, or a mixed solvent thereof. The curability of the exposed area is good, but since the radiation-sensitive component is not soluble in water, alcohol, or a mixed solvent of these, the radiation-sensitive component in the unexposed area cannot be developed. In other words, a region that would serve as a scaffold for cells could not be formed. Therefore, formation of cell clusters of the seeded cells could not be confirmed.

According to the present invention, a radiation-sensitive scaffolding material capable of forming a hydrogel pattern can be provided.
In addition, the patterned hydrogel scaffold obtained by exposing and developing the radiation-sensitive scaffold has excellent transparency and can provide a suitable scaffold for cell culture, forming cell clusters selectively in desired areas. can be done. Therefore, it is expected to be applied as a cell culture instrument and a cell culture device.

Claims (8)

Fibrous cellulose with an average fiber width of 100 nm or less,
Contains a negative radiation-sensitive component containing a polymerizable compound and a polymerization initiator,
The content of the negative radiation-sensitive component is 20 to 200 parts by mass based on 100 parts by mass of the fibrous cellulose,
The negative radiation-sensitive component is a component that is soluble in at least one selected from water, alcohol, and a mixed solvent thereof;
Scaffolding material for cell culture. The cell culture scaffold material according to claim 1, having a hydrogel pattern formed by exposing and developing the cell culture scaffold material. The scaffolding material for cell culture according to claim 1, wherein the polymerizable compound has at least one group selected from a (meth)acryloyloxy group and a (meth)acrylamide group. The cell culture scaffold material according to claim 1, having a haze of 10% or less. A part of the scaffold material for cell culture according to any one of claims 1 to 4 is irradiated with radiation, and the unexposed part is washed and removed with at least one selected from water and a solvent containing water. , a method for producing a scaffold for cell culture, comprising a step of forming a hydrogel pattern. A method for producing cultured cells, comprising the step of culturing cells on the scaffold for cell culture according to any one of claims 1 to 4. A method for producing spheres, comprising the step of culturing cells on the scaffold for cell culture according to any one of claims 1 to 4. A cell culture container comprising the cell culture scaffold material according to claim 2, wherein at least a portion of a cell culture area is provided with the hydrogel pattern.

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