Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/08—Macromolecular additives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J177/00—Adhesives based on polyamides obtained by reactions forming a carboxylic amide link in the main chain; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J201/00—Adhesives based on unspecified macromolecular compounds
  • C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
  • C09J201/06—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
  • C09J201/08—Carboxyl groups

Definitions

• the present invention relates to an adhesive composition, its manufacturing method, and an article.
• nanocellulose such as cellulose nanofiber, which is obtained by refining various cellulosic raw materials, for example, in place of petroleum-derived materials is being considered.
• nanocellulose is attracting attention as a functional material because it is lightweight and has strength.
• Patent Document 1 a fine cellulose fiber composite containing a water-insoluble resin, a fine cellulose fiber containing an ionic group such as a carboxyl group and/or a modifying group bound to the fine cellulose fiber is contained.
• An adhesive composition is disclosed. This adhesive composition is said to be excellent in adhesiveness.
• Patent Document 2 discloses an adhesive composition for the purpose of preventing collapse of cargo. Such an adhesive composition is required to have both a large shearing force for suppressing external vibration and inclination and a small peel strength for easy peeling after use.
• the adhesive composition of Patent Document 2 contains cellulose nanofibers, which is said to increase the value of the ratio of shear adhesive strength to peel strength.
• Patent Literature 3 discloses an easily peelable adhesive composition characterized by containing cellulose nanofibers, which allows easy peeling of container labels and the like.
• Patent Document 4 discloses a soft epoxy resin composition containing cellulose nanofibers, an epoxy resin, and a curing agent, wherein the cured product of the soft epoxy resin composition has a tensile strength of 1 MPa or more and an elongation at break of is 10% or more, a flexible epoxy resin composition is disclosed. This soft epoxy resin composition is intended for use as a building repair material.
• nanocellulose As mentioned above, by blending nanocellulose into the adhesive, various functions are exhibited. However, when nanocellulose is added to a resin, which is the main component of the adhesive, the nanocellulose is not uniformly dispersed in the adhesive, resulting in insufficient functional impartation by the nanocellulose.
• An object of the present invention is to provide an adhesive composition with excellent dispersibility of nanocellulose.
• an adhesive composition containing a resin containing a carboxyl group and nanocellulose has excellent nanocellulose dispersibility, and have completed the present invention.
• the present invention is as follows.
• An adhesive composition comprising a resin containing a carboxy group and nanocellulose.
• the resin having a functional group reactive with the carboxy group includes an epoxy resin, The adhesive composition according to any one of [2] to [4], wherein the epoxy resin has 3 or more epoxy groups in one molecule.
• the adhesion according to any one of [1] to [12], wherein the content of the resin containing a carboxy group is 50 to 98% by mass based on the total mass of the resins contained in the adhesive composition. agent composition.
• a method for producing an adhesive composition containing a resin containing a carboxy group and nanocellulose obtaining the adhesive composition comprising the nanocellulose derived from the oxidized cellulose by stirring the oxidized cellulose and continuously mixing it with materials other than the nanocellulose of the adhesive composition;
• the production method wherein the oxidized cellulose contains an oxide of a cellulosic raw material produced by hypochlorous acid or a salt thereof and does not substantially contain an N-oxyl compound.
• An article comprising a cured product of the adhesive composition according to any one of [1] to [14].
• the article according to [17] which is selected from the group consisting of bonding films, laminates, flexible copper-clad laminates, flexible flat cables, and electromagnetic shielding films.
• An adhesive composition according to one embodiment of the present invention comprises a resin containing a carboxy group and nanocellulose.
• the reason why the dispersibility of nanocellulose is improved in the adhesive composition is assumed to be that the resin containing the carboxy group and the nanocellulose have excellent affinity, and the nanocellulose is easily dispersed in the resin containing the carboxy group. be.
• the present invention is in no way limited by the reason assumed above.
• An adhesive composition according to one embodiment of the present invention comprises a resin containing a carboxy group.
• the term "resin containing a carboxy group” refers to a resin having a carboxy group bonded in its molecule.
• a carboxy group may be in the form of a free acid or a salt.
• the carboxy group may also be in the form of an acid anhydride. Therefore, the carboxy group includes free acid forms, salt forms, and acid anhydride forms.
• the bonding position of the carboxyl group is not particularly limited, and it may be bonded to the main chain constituting the resin or may be bonded to a side chain.
• resins containing carboxy groups include nylon resins containing carboxy groups, polyester resins containing carboxy groups, acrylic resins containing carboxy groups, polyolefin resins containing carboxy groups, and polystyrene resins containing carboxy groups. , a polyimide resin containing a carboxy group, a maleimide resin containing a carboxy group, an epoxy resin containing a carboxy group, and the like.
• the carboxy group-containing resin may be obtained by subsequently introducing a carboxy group into a carboxy group-free resin.
• a resin containing a carboxy group may be used alone or in combination of two or more.
• nylon resin is synonymous with polyamide resin.
• the method for producing the nylon resin is not particularly limited. ring polymerization, a composite reaction thereof, and the like.
• dicarboxylic acids constituting nylon resins include adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimer acid, isophthalic acid, terephthalic acid, and sodium 5-sulfoisophthalate. Although not particularly limited, it is preferable to use azelaic acid and/or dodecanedioic acid from the viewpoint of ensuring solubility in a solvent.
• diamines constituting nylon resins include piperazine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, p-diaminomethylcyclohexane, bis(p-aminocyclohexyl)methane, m-xylenediamine, and isophoronediamine. is mentioned. Although not particularly limited, it is preferable to use piperazine from the viewpoint of improving adhesive strength.
• aminocarboxylic acids constituting nylon resins include 11-aminoundecanoic acid, 12-aminododecanoic acid, 4-aminomethylbenzoic acid, and 4-aminomethylcyclohexanecarboxylic acid.
• intramolecular cyclic compounds of aminocarboxylic acids that constitute nylon resins include ⁇ -lactam, ⁇ -caprolactam, laurinlactam, ⁇ -pyrrolidone, and ⁇ -piperidone.
• the resin containing a carboxy group has a predetermined acid value.
• the acid value range include 0.1 mgKOH/g to 20 mgKOH/g, 1 mgKOH/g to 15 mgKOH/g, 4 mgKOH/g to 10 mgKOH/g, and the like.
• Methods for adjusting the acid value include, for example, controlling the resin synthesis conditions and monomer ratio to adjust the amount of carboxy groups at the ends of the main chain and in the main chain; a method of introducing a physical structure into a resin. Specific examples include a method of copolymerizing an unsaturated carboxylic acid or its anhydride, and a method of modifying a resin with a carboxylic anhydride.
• a polyolefin resin such as polypropylene is graft-polymerized with an unsaturated carboxylic acid such as maleic anhydride, itaconic anhydride, acrylic acid, or methacrylic acid, or an anhydride thereof;
• an unsaturated carboxylic acid such as maleic anhydride, itaconic anhydride, acrylic acid, or methacrylic acid, or an anhydride thereof;
• a method of reacting an acid excessively to form an acid terminal a method of reacting a carboxylic acid anhydride with a polyamide resin, a raw material carboxylic acid component having two or more carboxylic acid anhydride structures such as pyromellitic anhydride.
• a method using a compound and the like can be mentioned.
• “acid value” means the number of mg of KOH required to neutralize the acid present in 1 g of resin containing carboxy groups. The acid value can be measured by the method described in Examples.
• the carboxy group-containing resin have a predetermined amine value.
• the amine value range include 1 mgKOH/g to 12 mgKOH/g, 2 mgKOH/g to 9 mgKOH/g, and 3 mgKOH/g to 6 mgKOH/g.
• Methods for adjusting the amine value include, for example, controlling the synthesis conditions and monomer ratio of the resin to adjust the amount of amino groups at the ends of the main chain and in the main chain, and introducing amino groups into the resin by modification, copolymerization, etc. method.
• "amine value” means the number of milligrams of KOH equivalent to hydrochloric acid required to neutralize the amine present in 1 gram of resin containing carboxyl groups. The amine value can be measured by the method described in Examples.
• the acid value is set to a certain value or less (the amine value is a certain value or more), so that the nylon resin and the epoxy group of the epoxy resin can be accelerated to sufficiently cure. Further, by setting the acid value to a certain value or more (the amine value to a certain value or less), excessive reaction acceleration can be suppressed and the storage stability can be improved.
• the resin containing carboxy groups is preferably soluble in the solvent contained or added to the adhesive composition. Since the carboxy group-containing resin is soluble in the solvent, the nanocellulose can be dispersed in the solvent, making it easier to obtain better dispersibility.
• solvent-soluble means that the amount of the resin containing a carboxyl group dissolved in 100 ml of a solvent at 25°C is 5 g or more.
• Nanocellulose An adhesive composition according to one embodiment of the present invention comprises nanocellulose.
• nanocellulose means cellulose that has been nanoized. Nanocellulose may be obtained by a nano-processing, or may be originally in nano form. Examples of nanocellulose include fine cellulose fibers (also called cellulose nanofibers (CNF)), cellulose nanocrystals, and the like.
• CNF cellulose nanofibers
• Oxidized cellulose as used herein means an oxide of a cellulosic raw material before fibrillation treatment (nanization treatment).
• the nanocellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and does not substantially contain an N-oxyl compound.
• hypochlorous acid or a salt thereof for oxidizing the cellulosic raw material and not using an N-oxyl compound such as TEMPO, it is possible to obtain nanocellulose substantially free of N-oxyl compounds.
• Such nanocellulose is highly safe because the impact of N-oxyl compounds on the environment and the human body is sufficiently reduced.
• N-oxyl compound of nanocellulose As used herein, the expression that nanocellulose "substantially does not contain an N-oxyl compound” means that no N-oxyl compound is used when producing oxidized cellulose, or that no N-oxyl compound is used in nanocellulose. It means that the amount of nitrogen derived from the N-oxyl compound is 2.0 mass ppm or less, preferably 1.0 mass ppm or less, relative to the total amount of nanocellulose. Further, when the amount of nitrogen derived from the N-oxyl compound is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less as an increase from the cellulosic raw material, "N-oxyl compound means “substantially free of”.
• the amount of nitrogen derived from the N-oxyl compound can be measured by known means.
• known means include a method using a trace total nitrogen analyzer.
• the nitrogen component derived from the N-oxyl compound in nanocellulose is measured as a nitrogen content using a trace total nitrogen analyzer (for example, manufactured by Nitto Seiko Analyticc Co., Ltd., device name: TN-2100H). can do.
• Nanocellulose preferably contains carboxy groups.
• the carboxy group of nanocellulose may be H type (-COOH) or salt type (-COO - X + : X + is a cation that forms a salt type), and the carboxy group may be converted to other It may be in a modified form by reacting with a compound to form a covalent bond.
• the type of salt is not particularly limited, but alkali metal salts such as lithium salts, sodium salts and potassium salts; alkaline earth metal salts such as calcium salts and barium salts; other metal salts such as magnesium salts and aluminum salts; salts, organic amine salts, and the like.
• Preferred examples of the other compounds include primary, secondary, and tertiary amines.
• the carboxy group content of nanocellulose is preferably 0.20 to 2.0 mmol/g.
• the amount of carboxyl groups in nanocellulose is equivalent to the amount of carboxyl groups in oxidized cellulose before defibration.
• the amount of carboxyl groups is 0.20 mmol/g or more, the oxidized cellulose can be imparted with sufficient easy disentanglement properties. This makes it possible to obtain a dispersion-stabilized adhesive composition even when defibration is performed under mild conditions.
• the amount of carboxyl groups is 2.0 mmol/g or less, excessive decomposition of oxidized cellulose can be suppressed during fibrillation treatment, and nanocellulose with a small proportion of particulate cellulose and uniform quality can be obtained.
• the amount of carboxy groups in nanocellulose is more preferably 0.30 mmol/g or more, still more preferably 0.35 mmol/g or more, still more preferably 0.40 mmol/g or more. It is more preferably 0.42 mmol/g or more, still more preferably 0.50 mmol/g or more, still more preferably over 0.50 mmol/g, and even more preferably 0.55 mmol/g or more.
• the upper limit of the amount of carboxyl groups may be less than 2.0 mmol/g, may be 1.5 mmol/g or less, may be 1.2 mmol/g or less, or may be 1.0 mmol/g or less. or 0.9 mmol/g or less.
• a preferable range of the amount of carboxyl groups can be determined by appropriately combining the above-mentioned upper limit and lower limit.
• the amount of carboxyl groups in nanocellulose is more preferably 0.30 mmol/g or more and less than 2.0 mmol/g, still more preferably 0.35 to 2.0 mmol/g, still more preferably 0.35 to 1 .5 mmol/g, still more preferably 0.40 to 1.5 mmol/g, even more preferably 0.50 to 1.2 mmol/g, even more preferably greater than 0.50 to 1.2 mmol /g, and even more preferably between 0.55 and 1.0 mmol/g.
• Nanocellulose is an aggregate of single unit fibers.
• the adhesive composition contains nanocellulose containing a carboxy group, it is sufficient that it contains at least one nanocellulose containing a carboxy group, and the nanocellulose containing a carboxy group is preferably the main component.
• the nanocellulose containing a carboxy group is the main component means that the ratio of the nanocellulose containing a carboxy group to the total amount of nanocellulose is more than 50% by mass, preferably more than 70% by mass. and more preferably more than 80% by mass. The upper limit of the above ratio is preferably 100% by mass, but may be 98% by mass or 95% by mass.
• the amount of carboxyl groups was obtained by adding 0.1 M hydrochloric acid aqueous solution to an aqueous solution of nanocellulose or oxidized cellulose and water to adjust the pH to 2.5, and then adding 0.05 N sodium hydroxide aqueous solution dropwise. It is a value calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization step of a weak acid in which the change in electrical conductivity is moderate, and the electrical conductivity is measured until the pH reaches 11.0. . Details are as described in Examples.
• the amount of carboxyl groups can be adjusted by changing the reaction time, reaction temperature, pH of the reaction solution, and the like in the oxidation reaction of the cellulosic raw material.
• Carboxy group weight a (ml) x 0.05/oxidized cellulose or nanocellulose mass (g)
• the average fiber length of nanocellulose is preferably 50 to 2000 nm, more preferably 100 to 1000 nm, still more preferably 100 to 700 nm, still more preferably 100 to 500 nm, still more preferably 100 to 100 nm. 400 nm.
• the average fiber length is within the above range, an increase in viscosity is suppressed, and an adhesive composition with stable dispersion can be obtained.
• the average fiber width of nanocellulose is preferably 1 to 200 nm, more preferably 1 to 15 nm, more preferably 1 to 10 nm, still more preferably 1 to 5 nm.
• the lower limit of the average fiber width may be 2.0 nm or 2.5 nm.
• the range of difference in values depending on the conditions is preferably within the range of ⁇ 100 nm for the average fiber length.
• the range of difference in values depending on conditions is preferably within the range of ⁇ 10 nm for the average fiber width.
• the aspect ratio (average fiber length/average fiber width) of nanocellulose is preferably 20 or more and 200 or less. When the aspect ratio is 200 or less, the dispersibility of nanocellulose can be further improved. From this point of view, the aspect ratio is more preferably 190 or less, still more preferably 180 or less. When the aspect ratio is 20 or more, aggregation due to uneven distribution of nanocellulose can be suppressed. From this point of view, the aspect ratio is more preferably 30 or more, still more preferably 40 or more. The range of the aspect ratio can be set by appropriately combining the above lower limit and upper limit.
• the zeta potential of nanocellulose is preferably -30 mV or less.
• the zeta potential is -30 mV or less (that is, the absolute value is 30 mV or more)
• sufficient repulsion between cellulose microfibrils is obtained, and nanocellulose with a high surface charge density is likely to be produced during mechanical defibration. This improves the dispersibility of nanocellulose.
• the upper limit of the zeta potential is not particularly limited, it is usually -100 mV or less.
• the zeta potential is ⁇ 100 mV or more (that is, the absolute value is 100 mV or less), oxidative cutting in the fiber direction accompanying the progress of oxidation tends to be suppressed, so nanocellulose of uniform size can be obtained.
• the zeta potential can be adjusted by changing the reaction time, reaction temperature, stirring conditions, etc. of the oxidation reaction of the cellulosic raw material.
• the zeta potential of nanocellulose is more preferably ⁇ 35 mV or less, more preferably ⁇ 40 mV or less, and even more preferably ⁇ 50 mV or less.
• the zeta potential of nanocellulose is preferably ⁇ 90 mV or higher, more preferably ⁇ 85 mV or higher, even more preferably ⁇ 80 mV or higher, even more preferably ⁇ 77 mV or higher, even more preferably ⁇ 70 mV or higher, and even more preferably ⁇ 65 mV or higher.
• the range of zeta potential can be set by appropriately combining the above lower limit and upper limit.
• the zeta potential is preferably ⁇ 90 mV or more and ⁇ 30 mV or less, more preferably ⁇ 85 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 80 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 77 mV or more and ⁇ 30 mV or less. more preferably ⁇ 70 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 65 mV or more and ⁇ 30 mV or less, and still more preferably ⁇ 65 mV or more and ⁇ 35 mV or less.
• the zeta potential is a value measured under conditions of pH 8.0 and 20° C. for a cellulose aqueous dispersion obtained by mixing nanocellulose and water to a nanocellulose concentration of 0.1% by mass. Specifically, it can be measured according to the following method. Pure water is added to the nanocellulose aqueous dispersion to dilute the nanocellulose concentration to 0.1%. A 0.05 mol/L sodium hydroxide aqueous solution is added to the diluted nanocellulose aqueous dispersion to adjust the pH to 8.0, and a zeta potential measuring device such as a zeta potential meter (ELSZ-1000) manufactured by Otsuka Electronics Co., Ltd. The zeta potential is measured at 20° C. by
• the light transmittance of a dispersion obtained by mixing nanocellulose with water to a solid content concentration of 0.1% by mass is preferably 95% or more, more preferably 96% or more, and still more preferably 97% or more. Yes, more preferably 99% or more.
• the light transmittance can be adjusted by changing the reaction time, reaction temperature, stirring conditions, etc. of the oxidation reaction of the cellulosic raw material.
• the light transmittance is measured at a wavelength of 660 nm with a spectrophotometer such as JASCO V-550 after placing the nanocellulose aqueous dispersion in a quartz cell with a thickness of 10 mm.
• a spectrophotometer such as JASCO V-550
• the degree of polymerization of oxidized cellulose before defibration of nanocellulose is preferably 600 or less.
• the energy required for defibration can be reduced, and the amount of oxidized cellulose that is insufficiently defibrated can be reduced.
• the lower limit of the degree of polymerization of oxidized cellulose is not particularly limited, it is preferably 50 or more from the viewpoint of reducing the proportion of particulate cellulose.
• the degree of polymerization of oxidized cellulose is more preferably 580 or less, still more preferably 560 or less, even more preferably 550 or less, still more preferably 500 or less, still more preferably 450 or less, and More preferably, it is 400 or less.
• the degree of polymerization of oxidized cellulose is more preferably 60 or more, still more preferably 70 or more, still more preferably 80 or more, still more preferably 90 or more, still more preferably 100 or more, and It is more preferably 110 or more, and particularly preferably 120 or more.
• the range of the degree of polymerization can be set by appropriately combining the above lower limit and upper limit.
• the degree of polymerization of oxidized cellulose is more preferably 60 to 600, still more preferably 70 to 600, even more preferably 80 to 600, still more preferably 80 to 550, and still more preferably 80 to 600. 500, more preferably 80-450, particularly preferably 80-400.
• the degree of polymerization of oxidized cellulose can be adjusted by changing the reaction time of the oxidation reaction, reaction temperature, pH, stirring conditions, effective chlorine concentration of hypochlorous acid or its salt, and the like. For example, the degree of polymerization tends to decrease when the reaction time of the oxidation reaction is lengthened and the reaction temperature is raised. In addition, the degree of polymerization tends to decrease by, for example, using a stirring blade or the like to sufficiently homogenize the reaction system.
• the degree of polymerization of oxidized cellulose is the average degree of polymerization (viscosity average degree of polymerization) measured by a viscosity method. Details are as follows. Oxidized cellulose is added to an aqueous solution of sodium borohydride adjusted to pH 10, and reduction treatment is performed at 25° C. for 5 hours. The amount of sodium borohydride is 0.1 g per 1 g of oxidized cellulose. After the reduction treatment, solid-liquid separation is performed by suction filtration, washing with water is performed, and the obtained oxidized cellulose fibers are freeze-dried.
• DP 175 x [ ⁇ ]
• Nanocellulose may be commercially available or may be produced.
• a method for producing nanocellulose includes, for example, a step A of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof to obtain oxidized cellulose, and a step B of defibrating the oxidized cellulose.
• the cellulosic raw material is not particularly limited as long as it is mainly composed of cellulose, and examples include pulp, natural cellulose, regenerated cellulose, and fine cellulose depolymerized by mechanically treating cellulose.
• the cellulosic raw material commercially available products such as crystalline cellulose made from pulp can be used as they are.
• unused biomass containing a large amount of cellulose components, such as bean curd refuse and soybean hulls, may be used as a raw material.
• the cellulosic raw material may be preliminarily treated with an alkali of an appropriate concentration for the purpose of facilitating penetration of the oxidizing agent to be used into the raw pulp.
• the cellulosic raw material fine cellulose obtained by mechanical or chemical treatment of cellulose may be used.
• fine cellulose powdered pulp can be suitably used. By using powdered pulp, there is a tendency that the miniaturization progresses further and nanocellulose can be efficiently obtained.
• the particle size of the powder pulp is usually in the range of 1 to 1000 ⁇ m, preferably in the range of 1 to 500 ⁇ m, more preferably in the range of 1 to 100 ⁇ m.
• the particle size referred to here is the average particle size, and means the value when the volume accumulation distribution is 50% when the particle size distribution is expressed as a volume accumulation distribution using a laser scattering method as the measurement principle. .
• Hypochlorous acid or salts thereof used for oxidizing cellulosic raw materials include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite. is mentioned. Among these, sodium hypochlorite is preferable from the viewpoint of ease of handling.
• a method for producing oxidized cellulose by oxidizing a cellulosic raw material includes a method of mixing a cellulosic raw material with a reaction solution containing hypochlorous acid or a salt thereof.
• the solvent contained in the reaction solution is preferably water because it is easy to handle and hardly causes side reactions.
• the effective chlorine concentration of hypochlorous acid or its salt in the reaction solution is preferably 7-43% by mass, more preferably 6-43% by mass.
• the effective chlorine concentration of the reaction liquid is preferably 7-43% by mass, more preferably 6-43% by mass.
• the effective chlorine concentration of the reaction solution is more preferably 14% by mass or more, still more preferably 15% by mass or more, still more preferably 18% by mass or more, and still more preferably 20% by mass or more.
• the effective chlorine concentration of the reaction solution is more preferably 40% by mass or less, and still more preferably 38% by mass or less.
• the effective chlorine concentration range of the reaction solution can be set by appropriately combining the above lower limit and upper limit.
• the effective chlorine concentration range is preferably 16 to 43% by mass, more preferably 18 to 40% by mass.
• the effective chlorine concentration range is preferably 6% by mass or more and less than 14% by mass, more preferably 7% by mass or more and less than 14% by mass. It is more preferably 7% by mass or more and 13% by mass or less, and even more preferably 8% by mass or more and 13% by mass or less.
• hypochlorous acid is a weak acid that exists as an aqueous solution
• hypochlorites are compounds in which hydrogen in hypochlorous acid is replaced with other cations.
• sodium hypochlorite which is hypochlorite
• the concentration is measured as the amount of available chlorine in the solution, not the concentration of sodium hypochlorite. .
• the sample is accurately weighed, water, potassium iodide and acetic acid are added and left to stand, and the released iodine is titrated with a sodium thiosulfate solution using an aqueous starch solution as an indicator to measure the effective chlorine concentration. do.
• the oxidation reaction of the cellulosic raw material with hypochlorous acid or its salt is preferably carried out while adjusting the pH in the range of 5.0 to 15.0. Within this range, the oxidation reaction of the cellulosic raw material can be sufficiently advanced, and the amount of carboxyl groups in the oxidized cellulose can be sufficiently increased. This makes it possible to easily defibrate the oxidized cellulose.
• the pH of the reaction system is more preferably 7.0 or higher, still more preferably 8.0 or higher, still more preferably 8.5 or higher, still more preferably 9.0 or higher, and still more preferably 9.5 or higher. be.
• the pH of the reaction system is more preferably 14.5 or less, still more preferably 14.0 or less, even more preferably 13.0 or less, still more preferably 12.5 or less, and still more preferably 12.0 or less. Even more preferably, it is 11.5 or less.
• the pH range of the reaction system is more preferably 7.0 to 14.0, still more preferably 8.0 to 13.5, still more preferably 8.5 to 13.0.
• the stirring method is not particularly limited, and a known stirrer may be used. When using a stirrer with stirring blades, it is preferable to stir at a rotational speed of 50 to 300 rpm.
• the reaction temperature in the oxidation reaction is preferably 15°C to 100°C, more preferably 20°C to 90°C.
• the reaction time of the oxidation reaction can be appropriately set according to the degree of progress of the oxidation, but is preferably about 15 minutes to 50 hours.
• the reaction temperature is preferably 30° C. or higher and/or the reaction time is 30 minutes or longer.
• the dispersion medium may be exchanged.
• the dispersion medium after the exchange is preferably an alcohol-based dispersion medium from the viewpoint of further improving the dispersibility of the subsequently obtained nanocellulose.
• the alcohol-based dispersion medium include the alcohol-based solvents described in the ⁇ Solvent> section below.
• the alcohol-based dispersion medium is preferably methanol.
• the method for exchanging the dispersion medium include adding a desired dispersion medium after centrifuging and decanting the dispersion.
• the oxidized cellulose preferably has a structure in which at least two of the hydroxyl groups of the glucopyranose rings constituting the cellulose are oxidized, and the hydroxyl groups at the second and third positions of the glucopyranose rings are oxidized to introduce carboxy groups. It is more preferable to have a Moreover, it is preferable that the hydroxyl group at the 6th position of the glucopyranose ring in the present nanocellulose is not oxidized and remains as a hydroxyl group.
• the position of the carboxy group in the glucopyranose ring of oxidized cellulose can be analyzed by solid-state 13 C-NMR spectrum.
• Rayon has the same chemical structure as cellulose, and its oxide (rayon oxide) is water soluble.
• rayon oxide rayon oxide
• a carbon peak attributed to a carboxy group is observed at 165 to 185 ppm.
• two signals appear in this chemical shift range.
• solution two-dimensional NMR measurement it can be determined that the carboxy groups were introduced at the 2- and 3-positions.
• Solid 13 C-NMR of oxidized cellulose or nanocellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof shows two signals at 165 to 185 ppm when the amount of carboxyl groups introduced is large. , a very broad signal may appear when the amount of carboxyl group introduced is small.
• the signals of the carboxyl carbon atoms introduced at the 2nd and 3rd positions are close to each other, and solid-state 13 C-NMR with low resolution cannot sufficiently separate the two signals. Therefore, when the amount of carboxyl group introduced is small, a broad signal is observed.
• the introduction of carboxyl groups at the 2nd and 3rd positions can be confirmed by evaluating the spread of peaks appearing at 165 to 185 ppm. That is, after drawing a baseline to the peaks in the range of 165 ppm to 185 ppm in the solid 13 C-NMR spectrum and obtaining the overall area value, the two peak area values obtained by vertically dividing the area value at the peak top. A ratio (large area value/small area value) is obtained, and if the ratio of the peak area values is 1.2 or more, it can be said that the peak is broad.
• the presence or absence of the broad peak can be determined by the ratio of the length L of the baseline in the range of 165 ppm to 185 ppm to the length L' of the perpendicular line from the top of the peak to the baseline. That is, if the ratio L'/L is 0.1 or more, it can be determined that a broad peak exists.
• the ratio L'/L may be 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more.
• the upper limit of the ratio L'/L is not particularly limited, it is usually 3.0 or less, may be 2.0 or less, or may be 1.0 or less.
• the above-described glucopyranose ring structure of the present nanocellulose can also be determined by analysis according to the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.
• Step B defibration treatment
• the oxidized cellulose obtained in the step A can be fibrillated and nanoized to obtain nanocellulose.
• the defibration method includes, for example, weak stirring using a magnetic stirrer or the like, mechanical defibration, and the like. Although not particularly limited, mechanical defibration is preferable from the viewpoint of sufficiently defibrating in a short time.
• Mechanical fibrillation methods include, for example, a screw type mixer, a paddle mixer, a disper type mixer, a turbine type mixer, a homogenizer under high speed rotation, a high pressure homogenizer, an ultrahigh pressure homogenizer, a double cylindrical homogenizer, and an ultrasonic homogenizer. , water jet counter-collision disperser, beater, disc refiner, conical refiner, double disc refiner, grinder, single or multi-screw kneader, rotation or revolution stirrer, vibration stirrer, etc. method. These devices can be used alone or in combination of two or more.
• the pressure during defibration treatment is preferably 100 MPa or higher, more preferably 120 MPa or higher, and still more preferably 150 MPa or higher.
• the number of defibration treatments is not particularly limited, it is preferably two or more, more preferably three or more, from the viewpoint of sufficiently progressing defibration.
• the oxidized cellulose obtained in step A can be sufficiently fibrillated by mild stirring using a rotation/revolution stirrer, a vibrating stirrer, or the like.
• vibratory stirrers include vortex mixers (touch mixers).
• the dispersion medium is preferably an alcohol-based dispersion medium.
• the alcohol-based dispersion medium include the alcohol-based solvents described in the ⁇ Solvent> section below.
• the alcohol-based dispersion medium is preferably methanol.
• An adhesive composition according to one embodiment of the present invention contains a resin having a functional group reactive with a carboxy group (hereinafter referred to as a "second resin") in addition to a resin containing a carboxy group.
• a second resin a resin having a functional group reactive with a carboxy group
• the second resin include an epoxy resin having a functional group reactive to carboxy groups, an isocyanate resin having a functional group reactive to carboxy groups, and a functional group reactive to carboxy groups.
• Nylon resin polyester resin having functional groups reactive to carboxy groups, acrylic resins having functional groups reactive to carboxy groups, polyolefin resins having functional groups reactive to carboxy groups, carboxy groups Examples include polystyrene resins having functional groups reactive to , polyimide resins having functional groups reactive to carboxy groups, and maleimide resins having functional groups reactive to carboxy groups.
• the second resin may be a resin that does not have a reactive functional group with respect to a carboxyl group and subsequently has the functional group introduced therein.
• a 2nd resin may be used individually by 1 type, and may be used in combination of 2 or more type.
• the second resin having a functional group reactive to the carboxy group reacts or interacts with the resin containing the carboxy group and / or nanocellulose, thereby improving the adhesive strength and durability and dispersing the nanocellulose. sexuality is also improved.
• functional groups reactive with carboxy groups include epoxy groups, isocyanate groups, blocked isocyanate groups, ⁇ -hydroxyalkylamide groups, and hydroxyl groups.
• the second resin is preferably an epoxy resin.
• the second resin does not contain a carboxy group.
• the oxidation of the second resin is preferably less than 0.1 mgKOH/g.
• the acid value can be measured by the method described in Examples.
• epoxy resins include diglycidyl ether of bisphenol A and oligomers thereof, diglycidyl orthophthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl p-hydroxybenzoate, and diglycidyl tetrahydrophthalate.
• epoxy resins include novolak-type epoxy resins such as phenol novolac epoxy resin, o-cresol novolac epoxy resin,
• the epoxy resin preferably has 3 or more epoxy groups in one molecule.
• An adhesive composition according to one embodiment of the present invention may contain a solvent.
• the solvent preferably dissolves the resin containing a carboxyl group and the second resin.
• the solvent include alcohol-based solvents, ketone-based solvents, ester-based solvents, aromatic solvents, chlorine-based solvents, mixed solvents thereof, and the like. From the viewpoint of further improving the dispersibility of nanocellulose, the solvent preferably contains at least an alcohol solvent.
• a mixed solvent of an alcohol solvent and a ketone solvent a mixed solvent of an alcohol solvent and an ester solvent, an alcohol solvent and an aromatic solvent or a mixed solvent of an alcohol-based solvent and a chlorine-based solvent is preferable.
• the content of the alcohol-based solvent in the mixed solvent containing the alcohol-based solvent is preferably 30 to 80% by mass based on the mass of the mixed solvent.
• Alcohol solvents include methanol, ethanol, i-propyl alcohol, n-propyl alcohol, i-butyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol monomethyl ether, di Acetone alcohol and the like can be mentioned.
• Ketone solvents include, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone and the like.
• ester solvents include methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, 3-methoxybutyl acetate and the like.
• aromatic solvents include toluene, xylene, ethylbenzene, and mesitylene.
• chlorine-based solvents include chloroform, carbon tetrachloride, dichloromethane, and trichlorethylene.
• a mixed solvent such as methanol/toluene, i-propyl alcohol/toluene, or i-isopropyl alcohol/dichloromethane as the solvent.
• An adhesive composition according to one embodiment of the present invention may contain various additives.
• additives include coupling agents, antioxidants, ultraviolet absorbers, flame retardants, fillers, leveling agents, antifoaming agents, thickeners and dyes.
• Examples of coupling agents include silane-based coupling agents, titanate-based coupling agents, aluminate-based coupling agents, zirconium-based coupling agents, and the like.
• Examples of silane coupling agents include vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxy Silane etc. are mentioned.
• An adhesive composition according to one embodiment of the present invention includes a resin containing a carboxy group and nanocellulose, and may optionally include a solvent, a second resin, and other components.
• the content of the resin containing a carboxy group is preferably 50 to 98% by mass, more preferably 70 to 96% by mass, more preferably 70 to 96% by mass, based on the total mass of the resins contained in the adhesive composition. 80 to 94% by mass.
• the mass ratio of the carboxy group-containing resin to nanocellulose is preferably 0.1-15, more preferably 0.2-10, still more preferably 0.3-5. By setting the mass ratio within the above range, the dispersibility of nanocellulose can be further improved.
• the content of the carboxy group-containing resin is preferably 10 to 90% by mass, more preferably 15 to 85% by mass, based on the mass of the adhesive composition (excluding the solvent if it contains a solvent). Yes, more preferably 20 to 80% by mass.
• the content of nanocellulose is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, more preferably 10 to 80% by mass, based on the mass of the adhesive composition (excluding the solvent if it contains a solvent). is 15 to 70% by mass.
• the content of the second resin (especially epoxy resin) is preferably 2 to 50% by mass, more preferably 4 to 30% by mass, more preferably 4 to 30% by mass, based on the content of the resin containing a carboxy group. 6 to 20% by mass.
• the content of the solvent is preferably 30-90% by mass, more preferably 40-85% by mass, still more preferably 50-80% by mass, based on the mass of the adhesive composition.
• the content of the coupling agent is preferably 0.05 to 6% by mass, more preferably 0.1 to 4% by mass, and still more preferably 0, based on the content of the resin containing a carboxy group. .5 to 2% by mass.
• An article according to one embodiment of the present invention comprises a cured adhesive composition.
• the details of the adhesive composition are as described in the section ⁇ Adhesive composition> above.
• a bonding film comprising the adhesive composition.
• a laminate comprising an adhesive layer made of the adhesive composition and a substrate film laminated on at least one surface of the adhesive layer.
• a laminate comprising a cured layer obtained by curing the adhesive composition.
• a flexible copper-clad laminate comprising a copper foil, a cured layer obtained by curing the adhesive composition, and a substrate.
• a flexible flat cable comprising copper wiring, a cured layer obtained by curing the adhesive composition, and a covering material.
• An adhesive composition layer made of the adhesive composition, a B-stage adhesive composition layer obtained by partially curing the adhesive composition, or a cured product obtained by curing the adhesive composition An electromagnetic wave shielding film having layers.
• ⁇ Method for producing adhesive composition (1)> In a method for producing an adhesive composition according to one embodiment of the present invention, a mixture containing oxidized cellulose and a material other than nanocellulose in the adhesive composition is stirred to produce nanocellulose derived from the oxidized cellulose. wherein the oxidized cellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and is substantially free of an N-oxyl compound. .
• the details of the adhesive composition are as described in the section ⁇ Adhesive composition> above.
• the oxidized cellulose that has been oxidized using hypochlorous acid or its salt is defibrated into nanocellulose by being stirred together with other materials. Therefore, an adhesive composition containing nanocellulose can be produced by mixing and stirring oxidized cellulose together with other materials without independently defibrating the oxidized cellulose. Examples of the stirring method include the method described in the section [Step B: defibration treatment] above.
• oxidized cellulose is stirred and continuously mixed with a material other than the nanocellulose of the adhesive composition to obtain nanocellulose derived from the oxidized cellulose.
• the oxidized cellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and is substantially free of an N-oxyl compound.
• Continuous and “mixing with materials” as used herein means performing a series of actions of making the oxidized cellulose finer by stirring and mixing with the materials.
• Specific embodiments in which stirring and mixing are performed as a series of actions include, for example, an embodiment in which materials are added and mixed while the oxidized cellulose is stirred and pulverized (one-pot operation), and an embodiment in which the oxidized cellulose is stirred. (one-pot operation), and after pulverizing oxidized cellulose by stirring, it is added to the material and mixed (two-pot operation). .
• nanocellulose in this example were measured by the following methods.
• the sodium hypochlorite aqueous solution was stirred at 200 rpm with a stirrer (three-one motor, BL600) manufactured by Sintokagaku Co., Ltd. using a three-recessed-blade stirring blade and heated to 30°C in a constant temperature water bath. After that, 50 g of pulp powder (VP-1) manufactured by TDI Co., Ltd. was added as a cellulosic raw material.
• a stirrer three-one motor, BL600 manufactured by Sintokagaku Co., Ltd. using a three-recessed-blade stirring blade and heated to 30°C in a constant temperature water bath.
• 50 g of pulp powder (VP-1) manufactured by TDI Co., Ltd. was added as a cellulosic raw material.
• the purified oxidized cellulose was recovered by repeating centrifugation (1000 G, 10 minutes) and decantation, adding an amount of pure water corresponding to the removed liquid and dispersing. When the amount of carboxyl groups was measured, it was 0.70 mmol/g. Thereafter, hydrochloric acid was added to convert the carboxyl group of the oxidized cellulose from the salt form (-COO - Na + ) to the proton form (-COO - H + ), thereby obtaining an aqueous dispersion having a pH of 2.5.
• the average fiber length was 230 nm and the average fiber width was 4 nm.
• the residual nitrogen component derived from the N-oxyl compound in nanocellulose was 1.0 ppm or less.
• the residual nitrogen component was measured as nitrogen content using a trace total nitrogen analyzer (manufactured by Nitto Seiko Analytic Tech Co., Ltd., device name: TN-2100H), and calculated as an increase from the raw material pulp.
• the effective chlorine concentration in the sodium hypochlorite aqueous solution was measured by the following method. (Measurement of effective chlorine concentration in sodium hypochlorite aqueous solution) Accurately weigh 0.582 g of an aqueous solution of sodium hypochlorite pentahydrate crystals added to pure water, add 50 ml of pure water, add 2 g of potassium iodide and 10 ml of acetic acid, immediately seal tightly and store in a dark place for 15 minutes. I left it.
• the liberated iodine was titrated with a 0.1 mol/L sodium thiosulfate solution (indicator, starch test solution), and the titration amount was 34.55 ml.
• a blank test was performed separately and corrected. Since 1 ml of 0.1 mol/L sodium thiosulfate solution corresponds to 3.545 mg Cl, the effective chlorine concentration in the sodium hypochlorite aqueous solution is 21% by mass.
• the solid 13 C-NMR of the sample left at 23 ° C. and 50% RH for 24 hours or more was measured. It was confirmed to have a structure in which the hydroxyl group at the position was oxidized and a carboxyl group was introduced. Measurement conditions for solid-state 13 C-NMR are shown below.
• the above amine value was obtained by dissolving 3 g of nylon resin in a mixed solution of 20 ml of 1-butanol and 20 ml of toluene, and using an automatic titrator "AT-510" manufactured by Kyoto Electronics Industry Co., Ltd. as a buret "APB-510-01B” manufactured by the same company. ” was connected and measured. Potentiometric titration was performed using a 0.1 mol/L 2-propanolic hydrochloric acid solution as a titrant, and the number of mg of hydrochloric acid and equivalent KOH per 1 g of resin was calculated.
• the acid value was measured by dissolving 1 g of nylon resin in 40 ml of benzyl alcohol, and using an automatic titrator "AT-510" manufactured by Kyoto Electronics Industry Co., Ltd. connected to "APB-510-20B” manufactured by the same company as a buret. . Potentiometric titration was performed using a 0.01 mol/L benzyl alcoholic KOH solution as a titration reagent, and the number of mg of KOH per 1 g of resin was calculated.
• Nylon resin obtained in the above [Synthesis of nylon resin]; 20 parts by mass, cresol novolac epoxy resin (manufactured by Nippon Steel Chemical & Materials, trade name “Epotato YDCN-701"); 2 parts by mass, and a silane coupling agent (Shin-Etsu Silicone Co., Ltd. trade name “KBM-402” 3-glycidoxypropyldimethoxysilane); 0.2 parts by mass was dissolved in 78 parts by mass of a mixed solvent of methanol/toluene 1/1 (mass ratio) to obtain a resin solution. got an A.
• the nanocellulose dispersion of Production Example 1 or the oxidized cellulose dispersion of Production Example 2 is added at the composition ratio (mass ratio) shown in Table 1, and stirred using a laboratory disper to obtain an adhesive. A composition was obtained. Although the oxidized cellulose dispersion was used in Examples 3 and 4 and Comparative Example 2, nanoization progressed in the mixture during the production due to the stirring.
• Dispersibility was visually evaluated by placing 20 ml of the adhesive composition immediately after stirring in a 30 ml glass sample bottle.
• the evaluation criteria were as follows. A: No precipitate was observed after standing for 1 hour. B: When left for 1 hour, a precipitate was observed. Stirred again and the sediment disappeared. C: A sediment was observed after standing for 1 hour. Stirring again did not eliminate the sediment. Since a uniform composition solution could not be obtained with this evaluation of C, the rest of the evaluation could not be performed.
• ⁇ Elastic modulus> A release PET film having a thickness of 38 ⁇ m was prepared, and the above-mentioned adhesive composition solution was roll-coated on its surface so as to have a thickness of 30 ⁇ m after drying, followed by drying at 120° C. for 2 minutes. Thereafter, this coated film was heat-treated in an oven at 170° C. for 1 hour. After that, the release PET film was peeled off to prepare a test piece A. Regarding the elastic modulus, this test piece A was subjected to dynamic viscoelasticity measurement (frequency 1 Hz, heating rate 2 ° C./min) according to JIS K7244-4, and tensile storage at 20 ° C., 80 ° C., and 120 ° C. in tensile mode. Elastic modulus E' (120°C) was measured.
• ⁇ CTE coefficient of linear expansion
• TMA Q400 thermomechanical analyzer
• the test piece A prepared in ⁇ Modulus of Elasticity> was heated from -20 ° C. to 150 ° C. at 5 ° C./min, and subjected to N 2 atmosphere.
• the CTE was measured in tensile mode.
• CTE is CTE from 0°C to 40°C.
• ⁇ Peel strength> A polyimide film having a thickness of 25 ⁇ m was prepared, and the above-mentioned adhesive composition solution was roll-coated on its surface so as to have a thickness of 30 ⁇ m after drying, followed by drying at 120° C. for 2 minutes. After that, a rolled copper foil having a thickness of 35 ⁇ m was superposed on the surface of the coated adhesive layer so as to be in surface contact, and laminated under the conditions of a temperature of 120° C., a pressure of 0.4 MPa, and a speed of 0.5 m/min. performed Then, this laminate (polyimide film/adhesive layer/copper foil) was heat-pressed for 30 minutes at a temperature of 180° C.

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