WO2018008736A1 - シート - Google Patents
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- WO2018008736A1 WO2018008736A1 PCT/JP2017/024908 JP2017024908W WO2018008736A1 WO 2018008736 A1 WO2018008736 A1 WO 2018008736A1 JP 2017024908 W JP2017024908 W JP 2017024908W WO 2018008736 A1 WO2018008736 A1 WO 2018008736A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/08—Cellulose derivatives
- C08L1/16—Esters of inorganic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/02—Cellulose; Modified cellulose
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
- C08L29/02—Homopolymers or copolymers of unsaturated alcohols
- C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
- C08L2205/16—Fibres; Fibrils
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2312/00—Crosslinking
Definitions
- the present invention relates to a sheet. Specifically, the present invention relates to a sheet containing fine fibrous cellulose.
- fibrous cellulose having a fiber diameter of 10 ⁇ m or more and 50 ⁇ m or less, in particular, fibrous cellulose (pulp) derived from wood has been widely used mainly as a paper product so far.
- fine fibrous cellulose having a fiber diameter of 1 ⁇ m or less is also known.
- a sheet composed of such fine fibrous cellulose and a composite sheet containing a fine fibrous cellulose-containing sheet and a resin have been developed.
- seat and composite sheet containing a fine fibrous cellulose since the contact point of fibers increases remarkably, it is known that tensile strength etc. will improve large.
- Patent Document 1 discloses a composite containing cellulose nanofibers and a polyvinyl alcohol polymer.
- Patent Document 2 discloses a method for producing a polyvinyl alcohol film including a step of casting a film-forming stock solution in which cellulose fibers having a number average fiber diameter of 2 to 150 nm are added to a polyvinyl alcohol resin.
- Patent Documents 1 and 2 describe that a part of the hydroxyl group of cellulose is oxidized to at least one functional group selected from the group consisting of a carboxyl group and an aldehyde group.
- Patent Document 3 discloses a coating process in which a dispersion containing fine fibers having a fiber diameter of 1000 nm or less is coated on a substrate, and a dispersion containing fine fibers coated on the substrate is dried.
- seat by doing is disclosed.
- a hydrophilic polymer can be added to the dispersion.
- JP 2010-242033 A Japanese Patent Laying-Open No. 2015-157955 International Publication WO2014 / 196357
- the present inventors have determined that the tensile strength of the sheet containing fibrous cellulose having a fiber width derived from pulp of 1000 nm or less and a polyvinyl alcohol-based resin is 15 MPa or more. By doing so, it was found that a sheet in which the occurrence of cracks during bending was suppressed was obtained.
- the present invention has the following configuration.
- a sheet comprising fibrous cellulose having a fiber width derived from pulp of 1000 nm or less and a polyvinyl alcohol-based resin, wherein the sheet has a tensile strength of 15 MPa or more.
- FIG. 1 is a graph showing the relationship between the amount of NaOH dripped with respect to the fiber material and the electrical conductivity.
- FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity for a fiber material having a carboxyl group.
- FIG. 3 is a diagram for explaining a method for evaluating the bending resistance of a sheet.
- the present invention relates to a sheet containing fibrous cellulose having a fiber width derived from pulp of 1000 nm or less and a polyvinyl alcohol-based resin.
- the tensile strength of the sheet of the present invention is 15 MPa or more.
- seat of this invention is a sheet
- seat of this invention is a sheet
- the tensile strength of the sheet of the present invention may be 15 MPa or more, preferably 20 MPa or more, more preferably 30 MPa or more, further preferably 40 MPa or more, and further preferably 50 MPa or more. , 60 MPa or more, particularly preferably 70 MPa or more, and most preferably 80 MPa or more.
- seat For example, it can be 500 Mpa or less.
- excellent bending resistance can be exhibited by setting the tensile strength within the above range.
- the present invention has succeeded in improving the bending resistance in a fine fibrous cellulose-containing sheet, and has found that such an effect can be exhibited by adjusting the tensile strength of the sheet.
- the tensile strength of the sheet is a value measured using a tensile tester Tensilon (manufactured by A & D) in accordance with JIS P8113.
- the test piece is conditioned for 24 hours at 23 ° C. and 50% relative humidity, and the measurement is performed under the conditions of 23 ° C. and 50% relative humidity.
- the tensile strength of the sheet can be within the above range.
- seat excellent in bending resistance can be obtained by controlling tensile strength more than a fixed value.
- the tensile elastic modulus of the sheet of the present invention may be 3.5 GPa or more, preferably 4.0 GPa or more, more preferably 4.5 GPa or more, and further preferably 5.0 GPa or more.
- seat although there is no restriction
- seat of this invention has the outstanding tensile strength.
- the tensile elastic modulus of the sheet is a value measured using a tensile tester Tensilon (manufactured by A & D) in accordance with JIS P8113.
- the sample When measuring the tensile modulus, the sample is conditioned for 24 hours at 23 ° C. and 50% relative humidity, and is measured under the conditions of 23 ° C. and 50% relative humidity.
- the resin type to be contained in the sheet is a polyvinyl alcohol resin, and further, the content of the polyvinyl alcohol resin and the content of the fine fibrous cellulose are appropriately controlled and balanced to obtain a tensile of the sheet.
- the elastic modulus can be within the above range.
- the yellowness of the sheet of the present invention is preferably 5.0 or less, more preferably 3.0 or less, further preferably 2.0 or less, and particularly preferably 1.5 or less. preferable.
- the yellowness of the sheet is the yellowness of the sheet obtained in the sheet forming process, and is the yellowness of the sheet before undergoing the heating and drying process described later.
- the yellowness of the sheet is a value measured according to JIS K 7373. Examples of the measuring device include Color Cute i (manufactured by Suga Test Instruments Co., Ltd.).
- the yellowness after vacuum drying the sheet of the present invention at 200 ° C. for 4 hours is preferably 55 or less, more preferably 50 or less, further preferably 40 or less, and 30 or less. Is more preferably 25 or less, and most preferably 20 or less.
- the yellowness of the sheet after vacuum drying at 200 ° C. for 4 hours is also a value measured according to JIS K 7373 in the same manner as described above.
- YI 2 -YI 1 value ( ⁇ YI) is preferably 55 or less, more preferably 50 or less, even more preferably 40 or less, still more preferably 30 or less, particularly preferably 25 or less, and 20 or less. Most preferably.
- ⁇ YI YI 2 -YI 1 value
- the total light transmittance of the sheet of the present invention is preferably 85% or more, more preferably 90% or more, and further preferably 91% or more. Further, the haze of the sheet is preferably 5% or less, more preferably 3% or less, further preferably 2% or less, and particularly preferably 1% or less. The haze of the sheet may be 0%.
- the present invention is also characterized in that a highly transparent sheet can be obtained.
- the total light transmittance of the sheet is a value measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7361 and haze in accordance with JIS K 7136. It is.
- a phosphoric acid group or a substituent derived from a phosphoric acid group is introduced into fine fibrous cellulose, and the resin species to be contained in the sheet is a polyvinyl alcohol resin. There is a tendency to easily adjust the value to the above range.
- the thickness of the sheet of the present invention is not particularly limited, but is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, and further preferably 20 ⁇ m or more.
- the upper limit of the thickness of the sheet is not particularly limited, but can be, for example, 1000 ⁇ m or less.
- seat can be measured with a stylus type thickness meter (Maltron 1202D by Marl).
- the basis weight of the sheet of the present invention is preferably 10 g / m 2 or more, more preferably 20 g / m 2 or more, and further preferably 30 g / m 2 or more. Further, the basis weight of the sheet is preferably 100 g / m 2 or less, and more preferably 80 g / m 2 or less.
- the basis weight of the sheet can be calculated in accordance with JIS P 8124.
- seat of this invention contains the fibrous cellulose whose fiber width derived from a pulp is 1000 nm or less.
- the fine fibrous cellulose is preferably a fiber having an ionic functional group.
- the ionic functional group is preferably an anionic functional group (hereinafter also referred to as an anionic group).
- the anionic group examples include a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), a carboxyl group or a substituent derived from a carboxyl group (sometimes simply referred to as a carboxyl group), In addition, it is preferably at least one selected from a sulfone group or a substituent derived from a sulfone group (sometimes simply referred to as a sulfone group), and at least one selected from a phosphate group and a carboxyl group Is more preferable, and a phosphate group is particularly preferable.
- the fibrous cellulose which has a phosphoric acid group may be called a phosphorylated fine fibrous cellulose.
- the content of fine fibrous cellulose is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably 55% by mass or more with respect to the total mass of the sheet. Moreover, it is preferable that content of a fine fibrous cellulose is 95 mass% or less.
- seat is not specifically limited, 0.05 time or more is preferable with respect to content of polyvinyl alcohol-type resin, 0.1 time or more is more preferable, 1/9 time Or more, 0.2 times or more, 0.25 times or more, 0.3 times or more, 0.4 times or more, 3/7 times or more, 0.5 times or more, 2/3 times or more, 40/54 times or more, It may be 1 time or more, or 59.9 / 40.1 times or more.
- the upper limit of the content of the fine fibrous cellulose in the sheet is not particularly limited, but is preferably 20 times or less, more preferably 15 times or less, still more preferably 10 times or less, relative to the content of the polyvinyl alcohol resin, 90 It may be 9.9 / 9.1 times or less, 5 times or less, 80/18 times or less, 4 times or less, or 59.9 / 40.1 times or less.
- the content of fine fibrous cellulose in the sheet is preferably 1 to 20 times the content of the polyvinyl alcohol-based resin, and more preferably 2 to 20 times. It is preferably 4 to 20 times, more preferably 4 to 10 times.
- the yellowness change ( ⁇ YI) of the sheet tends to be low.
- the content of fine fibrous cellulose in the sheet is preferably 0.05 to 1 times the content of the polyvinyl alcohol-based resin. 1 to 1 time is more preferable.
- a pulp is used from the point of being easy to acquire and cheap.
- the pulp include wood pulp, non-wood pulp, and deinked pulp.
- wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached craft Chemical pulps such as pulp (OKP) are listed.
- semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), mechanical pulps such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are not particularly limited.
- Non-wood pulp includes cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, cellulose isolated from sea squirts and seaweed, chitin, chitosan, etc., but is not particularly limited.
- the deinking pulp includes deinking pulp made from waste paper, but is not particularly limited. The pulp of this embodiment may be used alone or in combination of two or more.
- wood pulp containing cellulose and deinked pulp are preferable in terms of availability.
- chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refinement (defibration) is high, and the degradation of cellulose in the pulp is small, and the fineness of long fibers with a large axial ratio is high. It is preferable at the point from which fibrous cellulose is obtained.
- kraft pulp and sulfite pulp are most preferably selected. Sheets containing long fibrous fine fibrous cellulose having a large axial ratio tend to provide high strength.
- the average fiber width of the fine fibrous cellulose is 1000 nm or less as observed with an electron microscope.
- the average fiber width is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and further preferably 2 nm or more and 10 nm or less, but is not particularly limited.
- the average fiber width of the fine fibrous cellulose is less than 2 nm, the physical properties (strength, rigidity, dimensional stability) as the fine fibrous cellulose tend to be difficult to be expressed because the cellulose molecules are dissolved in water. .
- the fine fibrous cellulose is monofilamentous cellulose having a fiber width of 1000 nm or less, for example.
- Measurement of the fiber width of the fine fibrous cellulose by electron microscope observation is performed as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to prepare a sample for TEM observation. To do. When a wide fiber is included, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50000 times depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.
- One straight line X is drawn at an arbitrary location in the observation image, and 20 or more fibers intersect the straight line X.
- a straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.
- the average fiber width (sometimes simply referred to as “fiber width”) of fine fibrous cellulose is an average value of the fiber widths read in this way.
- the fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 ⁇ m or more and 1000 ⁇ m or less, more preferably 0.1 ⁇ m or more and 800 ⁇ m or less, and particularly preferably 0.1 ⁇ m or more and 600 ⁇ m or less.
- the fiber length of the fine fibrous cellulose can be determined by image analysis using TEM, SEM, or AFM.
- the fine fibrous cellulose preferably has an I-type crystal structure.
- the proportion of the I-type crystal structure in the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. In this case, further superior performance can be expected in terms of heat resistance and low linear thermal expansion coefficient.
- the degree of crystallinity is obtained by measuring an X-ray diffraction profile and determining the crystallinity by a conventional method (Seagal et al., Textile Research Journal, 29, 786, 1959).
- the fine fibrous cellulose preferably has a phosphate group or a substituent derived from a phosphate group.
- the phosphoric acid group is a divalent functional group equivalent to the phosphoric acid obtained by removing the hydroxyl group. Specifically, it is a group represented by —PO 3 H 2 .
- Substituents derived from phosphoric acid groups include substituents such as groups obtained by polycondensation of phosphoric acid groups, salts of phosphoric acid groups, and phosphoric acid ester groups. It may be a group.
- the phosphate group or the substituent derived from the phosphate group may be a substituent represented by the following formula (1).
- R represents 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.
- ⁇ is a monovalent or higher cation composed of an organic substance or an inorganic substance.
- the fiber raw material containing cellulose is reacted with at least one selected from a compound having a phosphate group and a salt thereof (hereinafter referred to as “phosphorylation reagent” or “compound A”).
- a phosphorylating reagent may be mixed in a powder or aqueous solution with a dry or wet fiber raw material.
- a phosphorylating reagent powder or an aqueous solution may be added to the fiber raw material slurry.
- the phosphoric acid group introduction step can be performed by reacting a fiber raw material containing cellulose with at least one selected from a phosphoric acid group-containing compound and a salt thereof (phosphorylation reagent or compound A). This reaction may be carried out in the presence of at least one selected from urea and derivatives thereof (hereinafter referred to as “compound B”).
- An example of a method for causing compound A to act on the fiber raw material in the presence of compound B is a method of mixing powder or an aqueous solution of compound A and compound B with a dry or wet fiber raw material.
- Another example is a method in which powders and aqueous solutions of Compound A and Compound B are added to the fiber raw material slurry.
- a method of adding an aqueous solution of Compound A and Compound B to a dry fiber material, or a powder or an aqueous solution of Compound A and Compound B to a wet fiber material is preferred.
- the compound A and the compound B may be added simultaneously, or may be added separately.
- the form of the fiber raw material is preferably cotton or thin sheet, but is not particularly limited.
- Compound A used in this embodiment is at least one selected from a compound having a phosphate group and a salt thereof.
- the compound having a phosphate group include, but are not limited to, phosphoric acid, lithium salt of phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, ammonium salt of phosphoric acid, and the like.
- the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate.
- Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate.
- Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate.
- Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.
- phosphoric acid and phosphoric acid are introduced efficiently from the viewpoint that the introduction efficiency of phosphate groups is high, the fibrillation efficiency is easily improved in the fibrillation process described later, the cost is low, and the industrial application is easy.
- Sodium salt, potassium salt of phosphoric acid, and ammonium salt of phosphoric acid are preferable.
- Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferable.
- the compound A is preferably used as an aqueous solution because the uniformity of the reaction is increased and the efficiency of introducing a phosphate group is increased.
- the pH of the aqueous solution of Compound A is not particularly limited, but is preferably 7 or less because the efficiency of introduction of phosphate groups is increased, and more preferably pH 3 or more and pH 7 or less from the viewpoint of suppressing the hydrolysis of pulp fibers.
- the pH of the aqueous solution of Compound A may be adjusted by, for example, using a phosphoric acid group-containing compound that exhibits acidity and an alkalinity, and changing the amount ratio thereof. You may adjust pH of the aqueous solution of the compound A by adding an inorganic alkali or an organic alkali to the thing which shows acidity among the compounds which have a phosphoric acid group.
- the amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material (absolute dry mass) is 0.5 mass% to 100 mass%. Or less, more preferably 1% by mass to 50% by mass, and most preferably 2% by mass to 30% by mass. If the amount of phosphorus atoms added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. Moreover, the cost of the compound A to be used can be suppressed while improving phosphorylation efficiency by making the addition amount of the phosphorus atom with respect to a fiber raw material into 100 mass% or less.
- Compound B used in this embodiment includes urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.
- Compound B is preferably used as an aqueous solution like Compound A. Moreover, since the uniformity of reaction increases, it is preferable to use the aqueous solution in which both compound A and compound B are dissolved.
- the amount of Compound B added to the fiber raw material is preferably 1% by mass or more and 500% by mass or less, more preferably 10% by mass or more and 400% by mass or less, and 100% by mass or more and 350% by mass or less. More preferably, it is more preferably 150% by mass or more and 300% by mass or less.
- amides or amines may be included in the reaction system.
- amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like.
- amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, and the like. Among these, triethylamine is known to work as a good reaction catalyst.
- the heat treatment temperature it is preferable to select a temperature at which a phosphate group can be efficiently introduced while suppressing thermal decomposition and hydrolysis reaction of the fiber. Specifically, it is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. Moreover, you may use a vacuum dryer, an infrared heating apparatus, and a microwave heating apparatus for a heating.
- the concentration of the compound A in the fiber raw material may be uneven, and the introduction of phosphate groups on the fiber surface may not proceed uniformly.
- a very thin sheet-like fiber material is used, or the fiber material and Compound A are kneaded or stirred with a kneader or the like and dried by heating or reduced pressure. The method should be taken.
- the heating device used for the heat treatment is preferably a device that can always discharge the moisture retained by the slurry and the moisture generated by the addition reaction of the fibers such as phosphate groups to the hydroxyl group of the fiber, such as a blower oven. Etc. are preferred. If water in the system is always discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the esterification, can be suppressed, and the acid hydrolysis of the sugar chain in the fiber can also be suppressed. A fine fiber having a high axial ratio can be obtained.
- the heat treatment time is also affected by the heating temperature, but it is preferably 1 second or more and 300 minutes or less, preferably 1 second or more and 1000 seconds or less after moisture is substantially removed from the fiber raw material slurry. Preferably, it is 10 seconds or more and 800 seconds or less.
- the amount of phosphate groups introduced can be within a preferred range by setting the heating temperature and the heating time to appropriate ranges.
- the amount of phosphate group introduced is preferably 0.1 mmol / g or more and 3.65 mmol / g or less, more preferably 0.14 mmol / g or more and 3.5 mmol / g or less per 1 g (mass) of fine fibrous cellulose.
- 0.2 mmol / g or more and 3.2 mmol / g or less is more preferable, 0.4 mmol / g or more and 3.0 mmol / g or less is particularly preferable, and most preferably 0.6 mmol / g or more and 2.5 mmol / g or less.
- the fiber raw material can be easily refined, and the stability of the fine fibrous cellulose can be enhanced.
- the introduction amount of the phosphate group within the above range, it is possible to leave hydrogen bonds between the fine fibrous celluloses while facilitating miniaturization, and good strength expression can be expected in the sheet. .
- the amount of phosphate group introduced into the fiber material can be measured by a conductivity titration method. Specifically, by performing the defibration process step, after treating the resulting fine fibrous cellulose-containing slurry with an ion exchange resin, by determining the change in electrical conductivity while adding an aqueous sodium hydroxide solution, The amount introduced can be measured.
- first region the electrical conductivity rapidly decreases
- second region the conductivity starts to increase slightly
- third region the conductivity increment increases (hereinafter referred to as “third region”). That is, three areas appear.
- the boundary point between the second region and the third region is defined as a point at which the amount of change in conductivity twice, that is, the increase (inclination) in conductivity is maximized.
- the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration
- the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Will be equal.
- the amount of alkali required in the second region is reduced compared to the amount of alkali required in the first region.
- the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation, so that the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituent introduced (or the amount of substituents) is simply When said, it represents the amount of strongly acidic group. That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 is divided by the solid content (g) in the titration target slurry to obtain the substituent introduction amount (mmol / g).
- the phosphate group introduction step may be performed at least once, but may be repeated a plurality of times. In this case, more phosphoric acid groups are introduced, which is preferable.
- the fiber raw material is subjected to an oxidation treatment such as a TEMPO oxidation treatment, a compound having a carboxylic acid-derived group, a derivative thereof, or an acid thereof.
- oxidation treatment such as a TEMPO oxidation treatment
- Carboxyl groups can be introduced by treatment with an anhydride or derivative thereof.
- the compound having a carboxyl group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. .
- the acid anhydride of the compound having a carboxyl group is not particularly limited, but examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. It is done.
- the derivative of the compound having a carboxyl group is not particularly limited, and examples thereof include an acid anhydride imidized compound having a carboxyl group and an acid anhydride derivative of a compound having a carboxyl group. Although it does not specifically limit as an acid anhydride imidation thing of a compound which has a carboxyl group, Imidation thing of dicarboxylic acid compounds, such as maleimide, succinic acid imide, and phthalic acid imide, is mentioned.
- the acid anhydride derivative of the compound having a carboxyl group is not particularly limited.
- at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxyl group such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride, etc. are substituted (for example, alkyl group, phenyl group, etc. ) Are substituted.
- alkali treatment When manufacturing a fine fibrous cellulose, you may perform an alkali treatment between an ionic functional group introduction
- the alkali compound contained in the alkali solution is not particularly limited, but may be an inorganic alkali compound or an organic alkali compound.
- the solvent in the alkaline solution may be either water or an organic solvent.
- the solvent is preferably a polar solvent (polar organic solvent such as water or alcohol), and more preferably an aqueous solvent containing at least water.
- a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is particularly preferred because of its high versatility.
- the temperature of the alkali solution in an alkali treatment process is not specifically limited, 5 to 80 degreeC is preferable and 10 to 60 degreeC is more preferable.
- the immersion time in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or longer and 30 minutes or shorter, and more preferably 10 minutes or longer and 20 minutes or shorter.
- the usage-amount of the alkaline solution in an alkali treatment is not specifically limited, It is preferable that it is 100 mass% or more and 100,000 mass% or less with respect to the absolute dry mass of a phosphate group introduction
- the functional group-introduced fiber may be washed with water or an organic solvent before the alkali treatment step.
- the alkali treatment in order to improve the handleability, it is preferable to wash the alkali-treated functional group-introduced fiber with water or an organic solvent before the defibrating treatment step.
- the ionic functional group-introduced fiber is defibrated in the defibrating process.
- the fiber is usually defibrated using a defibrating apparatus to obtain a fine fibrous cellulose-containing slurry, but the processing apparatus and the processing method are not particularly limited.
- a defibrating apparatus a high-speed defibrator, a grinder (stone mill type pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type pulverizer, a ball mill, a bead mill, or the like can be used.
- a device for wet grinding such as a disk type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater should be used. You can also.
- the defibrating apparatus is not limited to the above.
- Preferable defibrating treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high pressure homogenizer that are less affected by the grinding media and less concerned about contamination.
- a polar organic solvent in addition to water, a polar organic solvent can be used.
- polar organic solvents include alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like, but are not particularly limited.
- alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butyl alcohol.
- ketones include acetone and methyl ethyl ketone (MEK).
- ethers include diethyl ether and tetrahydrofuran (THF).
- THF tetrahydrofuran
- the dispersion medium may be one type or two or more types. Further, the dispersion medium may contain a solid content other than the fiber raw material, such as urea having hydrogen bonding property.
- the fine fibrous cellulose may be obtained by once concentrating and / or drying the fine fibrous cellulose-containing slurry obtained by the defibrating treatment and then performing the defibrating treatment again.
- the concentration and drying methods are not particularly limited, and examples thereof include a method of adding a concentrating agent to a slurry containing fine fibrous cellulose, a generally used dehydrator, a press, and a method using a dryer.
- a well-known method for example, the method described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used.
- it can concentrate and dry by making a fine fibrous cellulose containing slurry into a sheet
- a high-speed defibrator As a device used when the fine fibrous cellulose slurry is concentrated and / or dried and then defibrated (pulverized) again, a high-speed defibrator, a grinder (stone mill pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, Use wet grinding equipment such as high-pressure collision type pulverizer, ball mill, bead mill, disk type refiner, conical refiner, twin-screw kneader, vibration mill, homomixer under high-speed rotation, ultrasonic disperser, beater, etc. However, it is not particularly limited.
- seat of this invention contains polyvinyl alcohol-type resin (PVA-type resin).
- the polyvinyl alcohol-based resin is obtained by saponifying polyvinyl acetate.
- the saponification degree of polyvinyl alcohol is not particularly limited, but is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, and more preferably 80 mol% or more. More preferably, it is still more preferably 85 mol% or more, particularly preferably 90 mol% or more, and most preferably 95 mol% or more.
- the saponification degree of polyvinyl alcohol may be 100 mol%, it is preferably 99 mol% or less, and more preferably 95 mol% or less.
- the degree of saponification of the polyvinyl alcohol resin can be measured according to JIS K 6726.
- the content of the polyvinyl alcohol-based resin is preferably 9% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and 30% by mass with respect to the total mass of the sheet. % Or more, more preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, the content of the polyvinyl alcohol-based resin is preferably 92% by mass or less, more preferably 80% by mass or less, further preferably 50% by mass or less, and 45% by mass or less. Is particularly preferred. In addition, content of polyvinyl alcohol-type resin can be measured, for example using IR measurement.
- the average degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but is preferably 300 or more, more preferably 400 or more, and further preferably 500 or more.
- the average degree of polymerization of the polyvinyl alcohol resin is preferably 20000 or less, more preferably 10,000 or less, further preferably 5000 or less, particularly preferably 2200 or less, and most preferably 1700 or less. preferable.
- the average degree of polymerization of the polyvinyl alcohol-based resin can be measured according to JIS K 6726.
- a polyvinyl alcohol-type resin it is an example of a preferable aspect that a polymerization degree is low and a caking degree is high (for example, average polymerization degree 1700 or less, caking degree 90 mol% or more).
- the polyvinyl alcohol-based resin may be an unmodified polyvinyl alcohol-based resin or a modified polyvinyl alcohol-based resin.
- the polyvinyl alcohol resin a combination of both an unmodified polyvinyl alcohol resin and a modified polyvinyl alcohol resin may be used.
- the modified polyvinyl alcohol resin is a polymer obtained by introducing a functional group other than a hydroxyl group and an acetate group into an unmodified polyvinyl alcohol resin.
- modified polyvinyl alcohol examples include carboxyl group-modified polyvinyl alcohol, carbonyl group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, and acetoacetyl group-modified polyvinyl alcohol. Etc. Among these, acetoacetyl group-modified polyvinyl alcohol is preferably used.
- the modified polyvinyl alcohol resin may be used alone or in combination of two or more. A part of the modified polyvinyl alcohol-based resin may form a self-crosslinking structure in the sheet manufacturing process. The modified polyvinyl alcohol resin can improve the strength of the sheet by forming a self-crosslinking structure.
- the polyvinyl alcohol-based resin is crosslinked to form a crosslinked polyvinyl alcohol.
- at least a part of the modified polyvinyl alcohol-based resin is crosslinked to form a crosslinked polyvinyl alcohol.
- a crosslinked structure is formed between functional groups (excluding hydroxyl groups and acetic acid groups) introduced into the modified polyvinyl alcohol resin.
- a crosslinking agent that forms a crosslinked structure a crosslinking agent described later can be used.
- Such a crosslinked structure can be detected by performing analysis such as NMR.
- the tensile strength can be improved as described above by appropriately controlling and balancing the content, saponification degree, and average polymerization degree of the polyvinyl alcohol resin.
- seat excellent in the bending resistance can be obtained by controlling tensile strength above a fixed value in this way.
- seat can be raised also by selecting the resin seed
- the sheet of the present invention preferably further contains at least one selected from a crosslinking agent and a functional group derived from the crosslinking agent.
- the cross-linking agent is preferably a cross-linking agent that cross-links the polyvinyl alcohol resin.
- the cross-linking agent added during the production of the sheet cross-links the polyvinyl alcohol resin, and a part of the cross-linked structure is detected as a functional group derived from the cross-linking agent. It becomes.
- the detection of the crosslinking agent and / or the functional group derived from the crosslinking agent can be analyzed using, for example, NMR measurement, IR measurement, MS fragment analysis, UV analysis, or the like.
- crosslinking agent examples include inorganic crosslinking agents such as chromium compounds, aluminum compounds, zirconium compounds, and boron compounds, glyoxal, glyoxylic acid and metal salts thereof, urea resins, polyamine polyamide epichlorohydrin, polyethyleneimine, carbodiimide compounds, oxazoline.
- Organic compounds such as organic compounds, aziridine compounds, hydrazine compounds, isocyanate compounds, melamine compounds, epoxy compounds, aldehyde compounds, N-methylol compounds, acryloyl compounds, active halogen compounds, ethyleneimino compounds
- a crosslinking agent, a metal, and a metal complex salt can be mentioned.
- the cross-linking agent is preferably a cross-linking agent that cross-links the polyvinyl alcohol-based resin.
- a cross-linking agent may cross-link the fine fibrous cellulose or the fine fibrous cellulose and the polyvinyl alcohol-based resin. Also good.
- hydrazine compounds include benzoic hydrazide, formic hydrazide, acetic hydrazide, propionic hydrazide, n-butyric hydrazide, isobutyric hydrazide, n-valeric hydrazide, isovaleric hydrazide, pivalic hydrazide, carbohydrazide, adipic acid Dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide dihydrazide polyhydride dihydrazide Etc.
- hydrazine compounds may be used alone or in combination of two or more.
- adipic acid dihydrazide is more preferable.
- crosslinked polyvinyl alcohol is obtained by crosslinking acetoacetyl group-modified polyvinyl alcohol, and adipic acid dihydrazide is used as a crosslinking agent, both terminal amino groups of adipic acid dihydrazide are respectively
- a crosslinked structure is formed by enamine reaction with the carbonyl group in the acetoacetyl group.
- various cross-linked polyvinyl alcohols can be formed by selecting a cross-linking agent and a modified polyvinyl alcohol according to the purpose.
- the content of the crosslinking agent is preferably 0.05% by mass or more and 30% by mass or less with respect to the total mass of the polyvinyl alcohol resin.
- content of polyvinyl alcohol-type resin is 5 mass% or more with respect to the total mass of a sheet
- content of polyvinyl alcohol-type resin is 50 mass% or less, and it is more preferable that it is 40 mass% or less.
- the total content of the polyvinyl alcohol-based resin, the crosslinking agent, and the functional group derived from the crosslinking agent can be calculated using NMR measurement, MS fragment analysis, IR measurement, UV analysis, or the like.
- the sheet of the present invention may contain an optional component other than the components described above.
- optional components include antifoaming agents, lubricants, ultraviolet absorbers, dyes, pigments, stabilizers, and surfactants.
- hydrophilic polymer except the said polyvinyl alcohol-type resin and a cellulose fiber), an organic ion, etc. are mentioned, for example.
- thermoplastic resin emulsion In addition to the polyvinyl alcohol resin, a thermoplastic resin emulsion, a thermosetting resin emulsion, a photocurable resin emulsion, or the like may be added to the sheet of the present invention.
- thermoplastic resin emulsion Specific examples of the thermoplastic resin emulsion, the thermosetting resin emulsion, and the photocurable resin emulsion include those described in JP-A-2009-299043.
- the production process of the sheet includes a step of obtaining a slurry containing fibrous cellulose having a fiber width of 1000 nm or less and a polyvinyl alcohol resin, a step of coating the slurry on a base material, or a step of papermaking the slurry. Including. Especially, it is preferable that the manufacturing process of a sheet
- the fine fibrous cellulose is preferably phosphorylated fine fibrous cellulose.
- the step of obtaining the slurry it is preferable to add 5 parts by mass or more of polyvinyl alcohol resin, more preferably 10 parts by mass or more, with respect to 100 parts by mass of the fine fibrous cellulose contained in the slurry, and 15 parts by mass. More preferably, more than 20 parts by mass are added.
- the addition amount of a polyvinyl alcohol-type resin is 200 mass parts or less, It is more preferable that it is 100 mass parts or less, It is further more preferable that it is 90 mass parts or less.
- the polyvinyl alcohol-based resin is preferably added in a state dissolved in water.
- the coating process is a process of obtaining a sheet by coating a slurry containing fine fibrous cellulose and a polyvinyl alcohol-based resin on a base material, and drying the formed sheet from the base material. is there.
- a coating apparatus and a long base material sheets can be continuously produced.
- the quality of the base material used in the coating process is not particularly limited, but the one with higher wettability to the slurry may be able to suppress the shrinkage of the sheet during drying, but the sheet formed after drying is easier It is preferable to select one that can be peeled off.
- a resin plate or a metal plate is preferable, but not particularly limited.
- resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates, iron plates, etc., and their surfaces oxidized, stainless steel A plate, a brass plate or the like can be used.
- a damming frame may be fixed on the base material to obtain a sheet having a predetermined thickness and basis weight. Good.
- the quality of the damming frame is not particularly limited, but it is preferable to select one that can easily peel off the edge of the sheet attached after drying. Among them, a molded resin plate or metal plate is preferable, but is not particularly limited.
- resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates, iron plates, etc., and their surfaces oxidized, stainless steel A plate, a brass plate or the like can be used.
- a coating machine for applying the slurry for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used.
- a die coater, a curtain coater, and a spray coater are preferable because the thickness can be made more uniform.
- the coating temperature is not particularly limited, but is preferably 20 ° C or higher and 45 ° C or lower, more preferably 25 ° C or higher and 40 ° C or lower, and further preferably 27 ° C or higher and 35 ° C or lower. If the coating temperature is not less than the above lower limit value, the slurry can be easily applied, and if it is not more than the above upper limit value, volatilization of the dispersion medium during coating can be suppressed.
- the coating step it is preferable to apply the slurry so that the finished basis weight of the sheet is 10 g / m 2 or more and 100 g / m 2 or less, preferably 20 g / m 2 or more and 60 g / m 2 or less.
- the basis weight is within the above range, a sheet having excellent strength can be obtained.
- the coating step preferably includes a step of drying the slurry coated on the substrate.
- a drying method Either a non-contact drying method or the method of drying while restraining a sheet
- the non-contact drying method is not particularly limited, but a method of drying by heating with hot air, infrared rays, far infrared rays or near infrared rays (heating drying method) or a method of drying in vacuum (vacuum drying method) is applied. Can do. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Although drying by infrared rays, far infrared rays, or near infrared rays can be performed using an infrared device, a far infrared device, or a near infrared device, it is not particularly limited.
- the heating temperature in the heat drying method is not particularly limited, but is preferably 20 ° C. or higher and 150 ° C.
- the heating temperature is not less than the above lower limit value, the dispersion medium can be volatilized quickly, and if it is not more than the above upper limit value, it is possible to suppress the cost required for heating and to prevent the fine fibrous cellulose from being discolored by heat. .
- the manufacturing process of the sheet may include a step of papermaking a slurry containing fine fibrous cellulose and a polyvinyl alcohol resin.
- Examples of the paper machine in the paper making process include a continuous paper machine such as a long-mesh type, a circular net type, and an inclined type, and a multi-layered paper machine combining these.
- known paper making such as hand making may be performed.
- the slurry is filtered and dehydrated on a wire to obtain a wet paper sheet, and then the sheet is obtained by pressing and drying.
- the filter cloth at the time of filtration is not particularly limited, but it is important that fine fibrous cellulose and polyvinyl alcohol resin do not pass through and the filtration rate is not too slow.
- seat, fabric, and porous film which consist of organic polymers are preferable.
- the organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and the like are preferable.
- Specific examples include a porous film of polytetrafluoroethylene having a pore size of 0.1 ⁇ m to 20 ⁇ m, for example, 1 ⁇ m, polyethylene terephthalate or polyethylene woven fabric having a pore size of 0.1 ⁇ m to 20 ⁇ m, for example, 1 ⁇ m, but is not particularly limited.
- This manufacturing apparatus discharges a slurry containing fine fibrous cellulose onto the upper surface of an endless belt, squeezes a dispersion medium from the discharged slurry, generates a web, and dries the web to dry the fiber sheet. And a drying section to produce.
- An endless belt is disposed from the squeezing section to the drying section, and the web generated in the squeezing section is conveyed to the drying section while being placed on the endless belt.
- the dehydration method that can be employed is not particularly limited, and examples include a dehydration method that is normally used in paper manufacture.
- a method of dehydrating with a long net, circular net, inclined wire, etc., and then dehydrating with a roll press is preferable.
- the drying method is not particularly limited, and examples thereof include methods used in paper production. For example, methods such as a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, and an infrared heater are preferable.
- the present invention may relate to a laminate having a structure in which another layer is further laminated on a sheet. Such other layers may be provided on both surfaces of the sheet, but may be provided only on one surface of the sheet.
- a resin layer and an inorganic layer can be mentioned, for example.
- the laminate include, for example, a laminate in which a resin layer is directly laminated on at least one surface of a sheet, a laminate in which an inorganic layer is directly laminated on at least one surface of a sheet, a resin layer, A sheet, a laminate in which inorganic layers are laminated in this order, a sheet, a resin layer, a laminate in which inorganic layers are laminated in this order, and a laminate in which sheets, inorganic layers, and resin layers are laminated in this order Can do.
- the layer structure of the laminate is not limited to the above, and various forms can be used depending on the application.
- the resin layer is a layer mainly composed of natural resin or synthetic resin.
- a main component refers to the component contained 50 mass% or more with respect to the total mass of a resin layer.
- the content of the resin is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and 90% by mass with respect to the total mass of the resin layer. The above is particularly preferable.
- content of resin can also be 100 mass%, and may be 95 mass% or less.
- Examples of natural resins include rosin resins such as rosin, rosin ester, and hydrogenated rosin ester.
- the synthetic resin is preferably at least one selected from, for example, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin, and acrylic resin.
- the synthetic resin is preferably at least one selected from polycarbonate resin and acrylic resin, and more preferably polycarbonate resin.
- the acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate.
- polycarbonate resin constituting the resin layer examples include an aromatic polycarbonate resin and an aliphatic polycarbonate resin. These specific polycarbonate resins are known and include, for example, the polycarbonate resins described in JP 2010-023275 A.
- the resin constituting the resin layer one kind may be used alone, or a copolymer obtained by copolymerization or graft polymerization of a plurality of resin components may be used. Moreover, you may use as a blend material which mixed the some resin component with the physical process.
- the adhesive layer may be provided between the sheet and the resin layer, or the adhesive layer may not be provided, and the sheet and the resin layer may be in direct contact with each other.
- an acrylic resin can be used as an adhesive constituting the adhesive layer.
- adhesives other than acrylic resins include vinyl chloride resin, (meth) acrylate resin, styrene / acrylate copolymer resin, vinyl acetate resin, vinyl acetate / (meth) acrylate ester.
- Examples include polymer resins, urethane resins, silicone resins, epoxy resins, ethylene / vinyl acetate copolymer resins, polyester resins, polyvinyl alcohol resins, ethylene vinyl alcohol copolymer resins, and rubber emulsions such as SBR and NBR. It is done.
- the resin layer may have an adhesion assistant, and surface treatment such as hydrophilic treatment may be performed on the surface of the resin layer.
- the adhesion assistant include a compound containing at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an oxazoline group, an amino group, and a silanol group, and an organosilicon compound.
- the adhesion assistant is preferably at least one selected from a compound containing an isocyanate group (isocyanate compound) and an organosilicon compound.
- organosilicon compounds include silane coupling agent condensates and silane coupling agents.
- surface treatment methods other than hydrophilization treatment include corona treatment, plasma discharge treatment, UV irradiation treatment, electron beam irradiation treatment, and flame treatment.
- the material constituting the inorganic layer is not particularly limited, but for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; these oxides, carbides, nitrides, oxycarbides, oxynitrides, or oxycarbonitrides Or a mixture thereof. From the viewpoint that high moisture resistance can be stably maintained, silicon oxide, silicon nitride, silicon oxide carbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxide carbide, aluminum oxynitride, or these Mixtures are preferred.
- the method for forming the inorganic layer is not particularly limited.
- a method for forming a thin film is roughly classified into a chemical vapor deposition method (chemical vapor deposition, CVD) and a physical film deposition method (physical vapor deposition, PVD), and either method may be adopted.
- CVD method include plasma CVD using plasma, and catalytic chemical vapor deposition (Cat-CVD) in which a material gas is contact pyrolyzed using a heating catalyst.
- Cat-CVD catalytic chemical vapor deposition
- PVD method include vacuum deposition, ion plating, and sputtering.
- an atomic layer deposition method (Atomic Layer Deposition, ALD) can also be employed.
- the ALD method is a method of forming a thin film in units of atomic layers by alternately supplying source gases of respective elements constituting a film to be formed to a surface on which a layer is formed.
- the film forming speed is slow, there is an advantage that it is possible to form a thin film with few defects because it can cleanly cover even a complicated surface more than the plasma CVD method.
- the ALD method has an advantage that the film thickness can be controlled on the nano order and it is relatively easy to cover a wide surface.
- the ALD method can be expected to improve the reaction rate, lower the temperature, and reduce the unreacted gas by using plasma.
- seat of this invention is suitable for the use of light transmissive substrates, such as various display apparatuses and various solar cells. It is also suitable for applications such as substrates for electronic devices, members of household appliances, various vehicles and building windows, interior materials, exterior materials, packaging materials, and the like. Furthermore, it is also suitable for applications in which the sheet itself is used as a reinforcing material in addition to threads, filters, fabrics, cushioning materials, sponges, abrasives, and the like.
- Example 1 ⁇ Production of phosphate group-introduced cellulose fiber>
- Oji Paper's pulp solid content 93% by mass, basis weight 208 g / m 2 sheet-like Canadian standard freeness (CSF) 700 ml, which is disaggregated and measured according to JIS P 8121
- CSF Canadian standard freeness
- 100 parts by mass (absolute dry mass) of the above-mentioned softwood kraft pulp is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and compressed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea. Pulp was obtained.
- the obtained chemical solution-impregnated pulp was dried with a dryer at 105 ° C. to evaporate the moisture and pre-dried. Then, it heated for 10 minutes with the ventilation dryer set to 140 degreeC, the phosphate group was introduce
- the obtained phosphoric acid-modified cellulose fiber had a phosphate group introduction amount of 0.98 mmol / g. Further, the fiber width of the obtained phosphoric acid-modified cellulose fiber was about 4 to 20 nm.
- Example 2 A sheet was obtained in the same manner as in Example 1 except that the addition amount of polyvinyl alcohol was adjusted to 25 parts by mass.
- Example 3 A sheet was obtained in the same manner as in Example 1 except that the addition amount of polyvinyl alcohol was adjusted to 67 parts by mass.
- Example 4 A sheet was obtained in the same manner as in Example 1 except that the addition amount of polyvinyl alcohol was adjusted to 100 parts by mass.
- Example 5 Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval 117, polymerization degree: 1700, saponification degree: 98 to 99 mol%) was added to ion exchange water so as to be 10% by mass, and the mixture was stirred at 95 ° C. for 1 hour to dissolve. A sheet was obtained in the same manner as in Example 1 except that this polyvinyl alcohol solution was used.
- Example 6 A sheet was obtained in the same manner as in Example 5 except that the addition amount of polyvinyl alcohol was adjusted to 25 parts by mass.
- Example 7 A sheet was obtained in the same manner as in Example 5 except that the addition amount of polyvinyl alcohol was adjusted to 67 parts by mass.
- Example 8 Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval 217, degree of polymerization: 1700, degree of saponification: 87-89 mol%) was added to ion exchange water so as to be 20% by mass, and the mixture was stirred at 95 ° C. for 1 hour to dissolve. A sheet was obtained in the same manner as in Example 3 except that this polyvinyl alcohol solution was used.
- Example 9 A sheet was obtained in the same manner as in Example 8 except that the addition amount of polyvinyl alcohol was adjusted to 100 parts by mass.
- Example 10 Polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval 124, degree of polymerization: 2400, degree of saponification: 98 to 99 mol%) was added to ion exchange water so as to be 5% by mass, and the mixture was stirred at 95 ° C. for 1 hour to dissolve. A sheet was obtained in the same manner as in Example 3 except that this polyvinyl alcohol solution was used.
- Example 11 To ion-exchanged water, acetoacetyl group-modified polyvinyl alcohol (Nippon Gosei Co., Ltd., Gohsenx Z200, degree of polymerization: 1200, degree of saponification: 99 mol% or more) was added to 10% by mass, and stirred at 95 ° C. for 1 hour. Dissolved. A sheet was obtained in the same manner as in Example 1 except that this acetoacetyl group-modified polyvinyl alcohol solution was added to 100 parts by mass of fine fibrous cellulose so that acetoacetyl group-modified polyvinyl alcohol was 25 parts by mass. .
- Example 12 A sheet was obtained in the same manner as in Example 11 except that the addition amount of the acetoacetyl group-modified polyvinyl alcohol was adjusted to 100 parts by mass.
- Example 13 The addition amount of acetoacetyl group-modified polyvinyl alcohol was adjusted to 22.5 parts by mass, and a crosslinking agent (manufactured by Nippon Kasei Chemical Co., Ltd., adipic acid dihydrazide, concentration: 35%) was added. A sheet was obtained in the same manner as in Example 12 except that 2.5 parts by mass was added.
- Example 14 The same procedure as in Example 13 was conducted, except that the addition amount of acetoacetyl group-modified polyvinyl alcohol was adjusted to 80 parts by mass and the crosslinking agent was changed so that the addition amount of adipic acid dihydrazide was 20 parts by mass. A sheet was obtained.
- Example 15 To ion-exchanged water, carbonyl-modified polyvinyl alcohol (D-Polymer DF20, manufactured by Nippon Vinegar Poval Co., Ltd.) was added to 10% by mass, and stirred at 95 ° C. for 1 hour to dissolve. A sheet was obtained in the same manner as in Example 14 except that this carbonyl-modified polyvinyl alcohol solution was used.
- D-Polymer DF20 manufactured by Nippon Vinegar Poval Co., Ltd.
- Example 16 Undried softwood bleached kraft pulp corresponding to a dry mass of 100 parts by mass, 1.6 parts by mass of TEMPO, and 10 parts by mass of sodium bromide were dispersed in 10,000 parts by mass of water. Subsequently, 13 mass% sodium hypochlorite aqueous solution was added so that the quantity of sodium hypochlorite might be 3.5 mmol with respect to 1.0 g of pulp, and reaction was started. During the reaction, a 1.0 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 or more and 11 or less. When no change was observed in the pH, the reaction was regarded as completed, and carboxyl groups were introduced into the pulp.
- Example 2 A sheet was obtained in the same manner as in Example 10 except that the polyvinyl alcohol was adjusted to 100 parts by mass.
- Substituent group measurement on cellulose surface The amount of phosphate groups introduced was measured by diluting cellulose with ion-exchanged water so that the content was 0.2% by mass, and then treating with ion-exchange resin and titration with alkali. In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (manufactured by Organo Corporation, Amberjet 1024: conditioned) is added to the 0.2 mass% cellulose-containing slurry, followed by shaking treatment for 1 hour. went. Thereafter, the mixture was poured onto a mesh having an opening of 90 ⁇ m to separate the resin and the slurry.
- a strongly acidic ion exchange resin manufactured by Organo Corporation, Amberjet 1024: conditioned
- the sheets obtained in the examples were excellent in bending resistance, and the occurrence of cracks during bending was suppressed.
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Abstract
Description
また、特許文献3には、繊維径が1000nm以下の微細繊維を含有する分散液を基材上に塗工する塗工工程と、基材上に塗工した微細繊維を含有する分散液を乾燥することによって微細繊維含有シートを形成する乾燥工程を含む微細繊維含有シートの製造方法が開示されている。ここでは、分散液中に親水性高分子を添加し得る旨の記載がある。
具体的に、本発明は、以下の構成を有する。
[2] 繊維状セルロースは、リン酸基又はリン酸基由来の置換基を有する[1]に記載のシート。
[3] ポリビニルアルコール系樹脂の含有量が、シートの全質量に対して20質量%以上である[1]又は[2]に記載のシート。
[4] ポリビニルアルコール系樹脂は、変性ポリビニルアルコール系樹脂である[1]~[3]のいずれかに記載のシート。
[5] 架橋剤及び架橋剤由来の官能基から選択される少なくともいずれかをさらに含有する[1]~[4]のいずれかに記載のシート。
本発明は、パルプ由来の繊維幅が1000nm以下の繊維状セルロースと、ポリビニルアルコール系樹脂と、を含むシートに関する。本発明のシートの引張強度は15MPa以上である。本発明のシートは、パルプ由来の繊維幅が1000nm以下の繊維状セルロース(以下、微細繊維状セルロースともいう)を含むシートであるため、微細繊維状セルロース含有シートと呼ぶこともできる。本発明のシートは、上記構成を有するシートであるため、屈曲時の割れの発生が抑制されている。すなわち、本発明のシートは、耐屈曲性に優れたシートである。
ここで、シートの引張強度は、JIS P 8113に準拠し、引張試験機テンシロン(エー・アンド・デイ社製)を用いて測定した値である。引張強度を測定する際には、23℃、相対湿度50%で24時間調湿したものを測定用の試験片とし、23℃、相対湿度50%の条件下で測定を行う。
そして、引張強度を一定値以上に制御することによって、耐屈曲性に優れたシートを得ることができる。
ここで、シートの引張弾性率は、JIS P 8113に準拠し、引張試験機テンシロン(エー・アンド・デイ社製)を用いて測定した値である。引張弾性率を測定する際には、23℃、相対湿度50%で24時間調湿したものを測定用の試験片とし、23℃、相対湿度50%の条件下で測定を行う。本発明においては、シートに含有させる樹脂種をポリビニルアルコール系樹脂とし、さらに、ポリビニルアルコール系樹脂の含有量や微細繊維状セルロースの含有量を適切に制御し、バランスをとることにより、シートの引張弾性率を上記範囲内とすることができる。
本発明のシートは、パルプ由来の繊維幅が1000nm以下の繊維状セルロースを含む。微細繊維状セルロースは、イオン性官能基を有する繊維であることが好ましく、この場合イオン性官能基は、アニオン性官能基(以下、アニオン基ともいう)であることが好ましい。アニオン基としては、例えば、リン酸基又はリン酸基に由来する置換基(単にリン酸基ということもある)、カルボキシル基又はカルボキシル基に由来する置換基(単にカルボキシル基ということもある)、及び、スルホン基又はスルホン基に由来する置換基(単にスルホン基ということもある)から選択される少なくとも1種であることが好ましく、リン酸基及びカルボキシル基から選択される少なくとも1種であることがより好ましく、リン酸基であることが特に好ましい。なお、本明細書においては、リン酸基を有する繊維状セルロースは、リン酸化微細繊維状セルロースと呼ぶこともある。
シートにおける微細繊維状セルロースの含有量の上限は、特に限定されないが、ポリビニルアルコール系樹脂の含有量に対して、20倍以下が好ましく、15倍以下がより好ましく、10倍以下がさらに好ましく、90.9/9.1倍以下、5倍以下、80/18倍以下、4倍以下、又は59.9/40.1倍以下でもよい。
ポリビニルアルコール系樹脂の含有量に対する微細繊維状セルロースの含有量が少ない場合には、シートの黄色度変化(ΔYI)が低くなる傾向がある。黄色度変化(ΔYI)が低いシートの製造を意図する場合には、シートにおける微細繊維状セルロースの含有量は、ポリビニルアルコール系樹脂の含有量に対して0.05倍~1倍が好ましく、0.1倍~1倍がより好ましい。
(2)同じ画像内で該直線と垂直に交差する直線Yを引き、該直線Yに対し、20本以上の繊維が交差する。
微細繊維状セルロースに占めるI型結晶構造の割合は30%以上であることが好ましく、より好ましくは50%以上、さらに好ましくは70%以上である。この場合、耐熱性と低線熱膨張率発現の点でさらに優れた性能が期待できる。結晶化度については、X線回折プロファイルを測定し、そのパターンから常法により求められる(Seagalら、Textile Research Journal、29巻、786ページ、1959年)。
リン酸基導入工程は、セルロースを含む繊維原料に対し、リン酸基を有する化合物及びその塩から選択される少なくとも1種(以下、「リン酸化試薬」又は「化合物A」という)を反応させることにより行うことができる。このようなリン酸化試薬は、乾燥状態または湿潤状態の繊維原料に粉末や水溶液の状態で混合してもよい。また別の例としては、繊維原料のスラリーにリン酸化試薬の粉末や水溶液を添加してもよい。
リン酸基を有する化合物としては、リン酸、リン酸のリチウム塩、リン酸のナトリウム塩、リン酸のカリウム塩、リン酸のアンモニウム塩などが挙げられるが、特に限定されない。リン酸のリチウム塩としては、リン酸二水素リチウム、リン酸水素二リチウム、リン酸三リチウム、ピロリン酸リチウム、またはポリリン酸リチウムなどが挙げられる。リン酸のナトリウム塩としてはリン酸二水素ナトリウム、リン酸水素二ナトリウム、リン酸三ナトリウム、ピロリン酸ナトリウム、またはポリリン酸ナトリウムなどが挙げられる。リン酸のカリウム塩としてはリン酸二水素カリウム、リン酸水素二カリウム、リン酸三カリウム、ピロリン酸カリウム、またはポリリン酸カリウムなどが挙げられる。リン酸のアンモニウム塩としては、リン酸二水素アンモニウム、リン酸水素二アンモニウム、リン酸三アンモニウム、ピロリン酸アンモニウム、ポリリン酸アンモニウムなどが挙げられる。
本発明においては、微細繊維状セルロースがカルボキシル基を有するものである場合、たとえば繊維原料にTEMPO酸化処理などの酸化処理を施すことや、カルボン酸由来の基を有する化合物、その誘導体、またはその酸無水物もしくはその誘導体によって処理することで、カルボキシル基を導入することができる。
微細繊維状セルロースを製造する場合、イオン性官能基導入工程と、後述する解繊処理工程の間にアルカリ処理を行ってもよい。アルカリ処理の方法としては、特に限定されないが、例えば、アルカリ溶液中に、官能基導入繊維を浸漬する方法が挙げられる。
アルカリ溶液に含まれるアルカリ化合物は、特に限定されないが、無機アルカリ化合物であってもよいし、有機アルカリ化合物であってもよい。アルカリ溶液における溶媒としては水または有機溶媒のいずれであってもよい。溶媒は、極性溶媒(水、またはアルコール等の極性有機溶媒)が好ましく、少なくとも水を含む水系溶媒がより好ましい。
また、アルカリ溶液のうちでは、汎用性が高いことから、水酸化ナトリウム水溶液、または水酸化カリウム水溶液が特に好ましい。
アルカリ処理工程におけるアルカリ溶液への浸漬時間は特に限定されないが、5分以上30分以下が好ましく、10分以上20分以下がより好ましい。
アルカリ処理におけるアルカリ溶液の使用量は特に限定されないが、リン酸基導入繊維の絶対乾燥質量に対して100質量%以上100000質量%以下であることが好ましく、1000質量%以上10000質量%以下であることがより好ましい。
イオン性官能基導入繊維は、解繊処理工程で解繊処理される。解繊処理工程では、通常、解繊処理装置を用いて、繊維を解繊処理して、微細繊維状セルロース含有スラリーを得るが、処理装置、処理方法は、特に限定されない。
解繊処理装置としては、高速解繊機、グラインダー(石臼型粉砕機)、高圧ホモジナイザーや超高圧ホモジナイザー、高圧衝突型粉砕機、ボールミル、ビーズミルなどを使用できる。あるいは、解繊処理装置としては、ディスク型リファイナー、コニカルリファイナー、二軸混練機、振動ミル、高速回転下でのホモミキサー、超音波分散機、またはビーターなど、湿式粉砕する装置等を使用することもできる。解繊処理装置は、上記に限定されるものではない。好ましい解繊処理方法としては、粉砕メディアの影響が少なく、コンタミの心配が少ない高速解繊機、高圧ホモジナイザー、超高圧ホモジナイザーが挙げられる。
本発明のシートは、ポリビニルアルコール系樹脂(PVA系樹脂)を含む。ポリビニルアルコール系樹脂は、ポリ酢酸ビニルをけん化して得られるものである。ポリビニルアルコールのけん化度は、特に限定されないが、50mol%以上であることが好ましく、60mol%以上であることがより好ましく、70mol%以上であることがより一層好ましく、80mol%以上であることがよりさらに好ましく、85mol%以上であることがさらに一層好ましく、90mol%以上であることが特に層好ましく、95mol%以上であることが最も好ましい。
また、ポリビニルアルコールのけん化度は100mol%であってもよいが、99mol%以下であることが好ましく、95mol%以下であることがより好ましい。なお、ポリビニルアルコール系樹脂のけん化度は、JIS K 6726に準じて測定することができる。
ポリビニルアルコール系樹脂としては、重合度が低く、かつけん化度が高いこと(例えば、平均重合度1700以下、かつけん化度90mol%以上)が好ましい態様の一例である。
本発明のシートは、架橋剤及び架橋剤由来の官能基から選択される少なくともいずれかをさらに含有することが好ましい。架橋剤は、ポリビニルアルコール系樹脂を架橋する架橋剤であることが好ましい。このように架橋剤及び/又は架橋剤由来の官能基を含有することにより、引張強度と引張弾性率のバランスに優れたシートが得られやすくなる。
本発明のシートが架橋剤由来の官能基を含む場合、シートの製造時に添加した架橋剤がポリビニルアルコール系樹脂を架橋し、その架橋構造の一部が架橋剤由来の官能基として検出されることとなる。架橋剤及び/又は架橋剤由来の官能基の検出は、例えば、NMR測定やIR測定、MSのフラグメント解析、UV解析などを用いて分析することができる。
本発明のシートには、上述した成分以外の任意成分が含まれていてもよい。任意成分としては、たとえば、消泡剤、潤滑剤、紫外線吸収剤、染料、顔料、安定剤、界面活性剤等を挙げることができる。また、任意成分としては、例えば、親水性高分子(上記ポリビニルアルコール系樹脂やセルロース繊維は除く)や有機イオン等が挙げられる。
シートの製造工程は、繊維幅が1000nm以下の繊維状セルロースと、ポリビニルアルコール系樹脂とを含むスラリーを得る工程と、このスラリーを基材上に塗工する工程、又は、スラリーを抄紙する工程を含む。中でも、シートの製造工程は、微細繊維状セルロースと、ポリビニルアルコール系樹脂とを含むスラリー(以下、単にスラリーということもある)を基材上に塗工する工程を含むことが好ましい。また、微細繊維状セルロースは、リン酸化微細繊維状セルロースであることが好ましい。
塗工工程は、微細繊維状セルロースと、ポリビニルアルコール系樹脂とを含むスラリーを基材上に塗工し、これを乾燥して形成されたシートを基材から剥離することによりシートを得る工程である。塗工装置と長尺の基材を用いることで、シートを連続的に生産することができる。
シートの製造工程は、微細繊維状セルロースと、ポリビニルアルコール系樹脂とを含むスラリーを抄紙する工程を含んでもよい。抄紙工程で抄紙機としては、長網式、円網式、傾斜式等の連続抄紙機、これらを組み合わせた多層抄き合わせ抄紙機等が挙げられる。抄紙工程では、手抄き等公知の抄紙を行ってもよい。
本発明は、シートにさらに他の層を積層した構造を有する積層体に関するものであってもよい。このような他の層は、シートの両表面上に設けられていてもよいが、シートの一方の面上にのみ設けられていてもよい。シートの少なくとも一方の面上に積層される他の層としては、例えば、樹脂層や無機層を挙げることができる。
樹脂層は、天然樹脂や合成樹脂を主成分とする層である。ここで、主成分とは、樹脂層の全質量に対して、50質量%以上含まれている成分を指す。樹脂の含有量は、樹脂層の全質量に対して、60質量%以上であることが好ましく、70質量%以上であることがより好ましく、80質量%以上であることがさらに好ましく、90質量%以上であることが特に好ましい。なお、樹脂の含有量は、100質量%とすることもでき、95質量%以下であってもよい。
密着助剤としては、例えば、イソシアネート基、カルボジイミド基、エポキシ基、オキサゾリン基、アミノ基及びシラノール基から選択される少なくとも1種を含む化合物や、有機ケイ素化合物が挙げられる。中でも、密着助剤はイソシアネート基を含む化合物(イソシアネート化合物)及び有機ケイ素化合物から選択される少なくとも1種であることが好ましい。有機ケイ素化合物としては、例えば、シランカップリング剤縮合物や、シランカップリング剤を挙げることができる。
なお、親水化処理以外の表面処理の方法としては、コロナ処理、プラズマ放電処理、UV照射処理、電子線照射処理、火炎処理等を挙げることができる。
無機層を構成する物質としては、特に限定されないが、例えばアルミニウム、ケイ素、マグネシウム、亜鉛、錫、ニッケル、チタン;これらの酸化物、炭化物、窒化物、酸化炭化物、酸化窒化物、もしくは酸化炭化窒化物;またはこれらの混合物が挙げられる。高い防湿性が安定に維持できるとの観点からは、酸化ケイ素、窒化ケイ素、酸化炭化ケイ素、酸化窒化ケイ素、酸化炭化窒化ケイ素、酸化アルミニウム、窒化アルミニウム、酸化炭化アルミニウム、酸化窒化アルミニウム、またはこれらの混合物が好ましい。
本発明のシートは、各種のディスプレイ装置、各種の太陽電池、等の光透過性基板の用途に適している。また、電子機器の基板、家電の部材、各種の乗り物や建物の窓材、内装材、外装材、包装用資材等の用途にも適している。さらに、糸、フィルタ、織物、緩衝材、スポンジ、研磨材などの他、シートそのものを補強材として使う用途にも適している。
<リン酸基導入セルロース繊維の作製>
針葉樹クラフトパルプとして、王子製紙製のパルプ(固形分93質量%、坪量208g/m2シート状 離解してJIS P 8121に準じて測定されるカナダ標準濾水度(CSF)700ml)を使用した。上記針葉樹クラフトパルプ100質量部(絶乾質量)に、リン酸二水素アンモニウムと尿素の混合水溶液を含浸し、リン酸二水素アンモニウム49質量部、尿素130質量部となるように圧搾し、薬液含浸パルプを得た。得られた薬液含浸パルプを105℃の乾燥機で乾燥し、水分を蒸発させてプレ乾燥させた。その後、140℃に設定した送風乾燥機で、10分間加熱し、パルプ中のセルロースにリン酸基を導入し、リン酸化パルプを得た。得られたリン酸化パルプ100質量部(絶乾質量)に対して10000質量部のイオン交換水を注ぎ、攪拌して均一に分散させた後、濾過脱水して、脱水シートを得る工程を2回繰り返し、リン酸変性セルロース繊維を得た。次いで、リン酸基を導入したセルロースに5000mlのイオン交換水を加え、撹拌洗浄後、脱水した。脱水後のパルプを5000mlのイオン交換水で希釈し、撹拌しながら、1Nの水酸化ナトリウム水溶液をpHが12以上13以下になるまで少しずつ添加して、パルプ分散液を得た。その後、このパルプ分散液を脱水し、5000mlのイオン交換水を加えて洗浄を行った。この脱水洗浄をさらに1回繰り返した。得られたリン酸変性セルロース繊維は、リン酸基の導入量が0.98mmol/gであった。また、得られたリン酸変性セルロース繊維の繊維幅は、4~20nm程度であった。
洗浄脱水後に得られたパルプにイオン交換水を添加して、固形分濃度が1.0質量%のパルプ懸濁液にした。このパルプ懸濁液を、湿式微粒化装置(スギノマシン社製、アルティマイザー)で245MPaの圧力にて5回処理し、微細繊維状セルロース懸濁液を得た。
イオン交換水に、ポリビニルアルコール(株式会社クラレ製、ポバール105、重合度:500、けん化度:98~99mol%)を20質量%になるように加え、95℃で1時間撹拌し、溶解した。
微細繊維状セルロース懸濁液にポリビニルアルコール溶液を添加し、微細繊維状セルロース100質量部に対し、ポリビニルアルコールが10質量部になるように調製した。次いで、固形分濃度が0.6質量%となるよう濃度調整を行った。シートの仕上がり坪量が45g/m2になるように懸濁液を計量して、市販のアクリル板上に展開し、70℃の乾燥機で24時間乾燥した。なお、所定の坪量となるようアクリル板上には堰止用の板を配置した。以上の手順により、シートが得られ、その厚みは30μmであった。
ポリビニルアルコールの添加量が25質量部となるように調製した以外は、実施例1と同様にしてシートを得た。
ポリビニルアルコールの添加量が67質量部となるように調製した以外は、実施例1と同様にしてシートを得た。
ポリビニルアルコールの添加量が100質量部となるように調製した以外は、実施例1と同様にしてシートを得た。
イオン交換水に、ポリビニルアルコール(株式会社クラレ製、ポバール117、重合度:1700、けん化度:98~99mol%)を10質量%になるように加え、95℃で1時間撹拌し、溶解した。このポリビニルアルコール溶液を用いた以外は、実施例1と同様にしてシートを得た。
ポリビニルアルコールの添加量が25質量部となるように調製した以外は、実施例5と同様にしてシートを得た。
ポリビニルアルコールの添加量が67質量部となるように調製した以外は、実施例5と同様にしてシートを得た。
イオン交換水に、ポリビニルアルコール(株式会社クラレ製、ポバール217、重合度:1700、けん化度:87~89mol%)を20質量%になるように加え、95℃で1時間撹拌し、溶解した。このポリビニルアルコール溶液を用いた以外は、実施例3と同様にしてシートを得た。
ポリビニルアルコールの添加量が100質量部となるように調製した以外は、実施例8と同様にしてシートを得た。
イオン交換水に、ポリビニルアルコール(株式会社クラレ製、ポバール124、重合度:2400、けん化度:98~99mol%)を5質量%になるように加え、95℃で1時間撹拌し、溶解した。このポリビニルアルコール溶液を用いた以外は、実施例3と同様にしてシートを得た。
イオン交換水に、アセトアセチル基変性ポリビニルアルコール(日本合成社製、ゴーセネックスZ200、重合度:1200、けん化度:99mol%以上)を10質量%になるように加え、95℃で1時間撹拌し、溶解した。このアセトアセチル基変性ポリビニルアルコール溶液を、微細繊維状セルロース100質量部に対し、アセトアセチル基変性ポリビニルアルコールが25質量部となるように添加した以外は、実施例1と同様にしてシートを得た。
アセトアセチル基変性ポリビニルアルコールの添加量が100質量部となるように調製した以外は、実施例11と同様にしてシートを得た。
アセトアセチル基変性ポリビニルアルコールの添加量が22.5質量部となるように調製し、さらに架橋剤(日本化成(株)製、アジピン酸ジヒドラジド、濃度:35%)をアジピン酸ジヒドラジドの添加量が2.5質量部となるように添加した以外は、実施例12と同様にしてシートを得た。
アセトアセチル基変性ポリビニルアルコールの添加量が80質量部となるように調製し、さらに架橋剤をアジピン酸ジヒドラジドの添加量が20質量部となるように変更した以外は、実施例13と同様にしてシートを得た。
イオン交換水に、カルボニル変性ポリビニルアルコール(日本酢ビ・ポバール株式会社製、DポリマーDF20)を10質量%になるように加え、95℃で1時間撹拌し、溶解した。このカルボニル変性ポリビニルアルコール溶液を用いた以外は、実施例14と同様にしてシートを得た。
乾燥質量100質量部相当の未乾燥の針葉樹晒クラフトパルプとTEMPO1.6質量部と、臭化ナトリウム10質量部とを水10000質量部に分散させた。次いで、13質量%の次亜塩素酸ナトリウム水溶液を、1.0gのパルプに対して次亜塩素酸ナトリウムの量が3.5mmolになるように加えて反応を開始した。反応中は1.0Mの水酸化ナトリウム水溶液を滴下してpHを10以上11以下に保ち、pHに変化が見られなくなった時点で反応終了と見なし、パルプにカルボキシル基を導入した。このパルプスラリーを脱水し、脱水シートを得た後、5000質量部のイオン交換水を注ぎ、攪拌して均一に分散させた後、濾過脱水して、脱水シートを得る工程を2回繰り返し、カルボキシル基変性セルロース繊維を得た。得られたカルボキシル基変性セルロース繊維は、カルボキシル基の導入量が1.01mmol/gであった。これを原料として用いた以外は、実施例4と同様にしてシートを得た。
ポリビニルアルコールが100質量部となるように調製した以外は、実施例5と同様にしてシートを得た。
ポリビニルアルコールが100質量部となるように調製した以外は、実施例10と同様にしてシートを得た。
<方法>
実施例及び比較例で作製したシートについて以下の評価方法に従って評価を実施した。
リン酸基の導入量は、セルロースをイオン交換水で含有量が0.2質量%となるように希釈した後、イオン交換樹脂による処理、アルカリを用いた滴定によって測定した。イオン交換樹脂による処理では、0.2質量%セルロース含有スラリーに体積で1/10の強酸性イオン交換樹脂(オルガノ株式会社製、アンバージェット1024:コンディショング済)を加え、1時間振とう処理を行った。その後、目開き90μmのメッシュ上に注ぎ、樹脂とスラリーを分離した。アルカリを用いた滴定では、イオン交換後の繊維状セルロース含有スラリーに、0.1Nの水酸化ナトリウム水溶液を加えながら、スラリーが示す電気伝導度の値の変化を計測した。すなわち、図1に示した曲線の第1領域で必要としたアルカリ量(mmol)を、滴定対象スラリー中の固形分(g)で除して、置換基導入量(mmol/g)とした。
カルボキシル基導入量は、図2(カルボキシル基)に示した曲線の第1領域で必要としたアルカリ量(mmol)を、滴定対象スラリー中の固形分(g)で除して、置換基導入量(mmol/g)とした。
JIS K 7361に準拠し、ヘーズメータ(村上色彩技術研究所社製、HM-150)を用いて全光線透過率を測定した。
JIS K 7136に準拠し、ヘーズメータ(村上色彩技術研究所社製、HM-150)を用いてヘーズを測定した。
JIS K 7373に準拠し、Colour Cute i(スガ試験機株式会社製)を用いてシート加熱前後の黄色度を測定した。なお、加熱後の黄色度は、200℃で4時間真空乾燥したシートの黄色度とした。また、黄色度の変化量としてΔYIを下記の式より算出した。
ΔYI=(加熱後の黄色度)-(加熱前の黄色度)
JIS P 8113に準拠し、引張試験機テンシロン(エー・アンド・デイ社製)を用いて引張弾性率及び引張強度を測定した。なお、引張弾性率及び引張強度を測定する際には、23℃、相対湿度50%で24時間調湿したものを試験片として用いた。
5cm角のシートを図3に示したように屈曲させ、図3におけるθが0°となるまで屈曲した際に割れないものは○、それ以外は×として評価した。なお、耐屈曲性を評価する際には、23℃、相対湿度50%で24時間調湿したものを試験片として用いた。
Claims (5)
- パルプ由来の繊維幅が1000nm以下の繊維状セルロースと、ポリビニルアルコール系樹脂と、を含むシートであって、
前記シートの引張強度が15MPa以上であるシート。 - 前記繊維状セルロースは、リン酸基又はリン酸基由来の置換基を有する請求項1に記載のシート。
- 前記ポリビニルアルコール系樹脂の含有量が、前記シートの全質量に対して9質量%以上である請求項1又は2に記載のシート。
- 前記ポリビニルアルコール系樹脂は、変性ポリビニルアルコール系樹脂である請求項1~3のいずれか1項に記載のシート。
- 架橋剤及び架橋剤由来の官能基から選択される少なくともいずれかをさらに含有する請求項1~4のいずれか1項に記載のシート。
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WO2021200355A1 (ja) * | 2020-03-30 | 2021-10-07 | 王子ホールディングス株式会社 | 感放射線性シート、およびパターン化されたシート |
WO2022004346A1 (ja) * | 2020-06-29 | 2022-01-06 | 株式会社クラレ | 水溶性フィルムおよび包装体 |
WO2022124290A1 (ja) * | 2020-12-07 | 2022-06-16 | 王子ホールディングス株式会社 | 生体高分子吸着シートおよびその製造方法 |
JP7260074B1 (ja) * | 2021-10-12 | 2023-04-18 | 星光Pmc株式会社 | 樹脂組成物及びその製造方法 |
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WO2017022848A1 (ja) * | 2015-08-05 | 2017-02-09 | 王子ホールディングス株式会社 | シート、シートの製造方法、および積層体 |
US11447612B2 (en) * | 2016-07-08 | 2022-09-20 | Oji Holdings Corporation | Sheet |
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WO2022124290A1 (ja) * | 2020-12-07 | 2022-06-16 | 王子ホールディングス株式会社 | 生体高分子吸着シートおよびその製造方法 |
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CN109415523A (zh) | 2019-03-01 |
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