Fibrous material for thermoforming and composite material for thermoforming

Abstract

This invention provides a fibrous material for thermoforming and a composite material for thermoforming, comprising anionicly modified pulp with thermoforming properties. The fibrous material for thermoforming in this embodiment comprises anionicly modified pulp in which at least 45 mol% of the anionic groups are onium salts. The composite material for thermoforming in this embodiment comprises anionicly modified pulp in which at least 45 mol% of the anionic groups are onium salts, and a thermoplastic resin.

Description

Technical Field

[0001] The present invention relates to a fibrous material for thermoforming comprising anionic modified pulp and a composite material for thermoforming, and a molded body formed therefrom by thermoforming the same. Background Technology

[0002] In recent years, materials using cellulose fibers, which are abundant in naturally occurring biomass, have attracted much attention from a sustainability perspective. For example, Patent Document 1 describes a fiber-reinforced resin composition comprising chemically modified cellulose nanofibers and thermoplastic resin. As one example, it describes obtaining a resin composition comprising chemically modified cellulose nanofibers and thermoplastic resin by mixing chemically modified pulp with thermoplastic resin and then defibrating the chemically modified pulp.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-176052 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] Cellulose fibers are inherently non-thermoforming. Therefore, they cannot be thermoformed unless added to resins such as thermoplastic resins. As mentioned above, while it is known that chemically modified cellulose fibers have been added to thermoplastic resins as reinforcing materials, it was previously unknown that certain anionic modified pulps possess thermoforming properties.

[0008] The purpose of this invention is to provide a novel thermoforming fibrous material and a thermoforming composite material comprising anionic modified pulp with thermoforming properties.

[0009] Technical means for solving problems

[0010] The present invention includes the embodiments shown below.

[0011] [1] A fibrous material for thermoforming, comprising anionic modified pulp in which at least 45 mol% of the anionic groups are onium salts.

[0012] [2] The thermoforming fibrous material as described in [1], wherein the melting point of the modifier used to make the anionic group into an onium salt is below 150°C.

[0013] [3] A fibrous material for thermoforming as described in [1] or [2], wherein the onium salt is a quaternary onium salt.

[0014] [4] A fibrous material for thermoforming as described in any one of [1] to [3], wherein the amount of anionic groups in the anionic modified pulp, as determined by making all the anionic groups acidic, is 0.5 to 3.0 mmol / g.

[0015] [5] A molded body is formed by thermoforming a fibrous material for thermoforming as described in any one of [1] to [4].

[0016] [6] A composite material for thermoforming, comprising: anionic modified pulp in which at least 45 mol% of the anionic groups are onium salts, and a thermoplastic resin.

[0017] [7] A molded body is formed by thermoforming the composite material for thermoforming described in [6].

[0018] Invention Effects

[0019] According to embodiments of the present invention, it is possible to provide a novel thermoforming fibrous material and a thermoforming composite material comprising anionic modified pulp having thermoforming properties. Detailed Implementation

[0020] [Fibrous materials for thermoforming]

[0021] The fibrous material for thermoforming in this embodiment comprises anionic modified pulp, wherein at least 45 mol% of the anionic groups in the anionic modified pulp are onium salts. Here, "fibrous material for thermoforming" refers to a material used in thermoforming, specifically one that is fibrous. "Thermoforming" refers to a molding method in which the material is softened by heating and shaped into a predetermined shape, and then solidified by cooling; examples include hot pressing, vacuum forming, and air-forming. Furthermore, softening here does not necessarily mean melting the pulp (cellulose fibers), but rather that the fibers become easily flowable upon heating, and that thermoforming allows the fibers to adhere together, which is then solidified by cooling to maintain a certain shape. "Fiber-like" refers to a material having a fibrous form, being an aggregate of fibers; for example, it can be a fibrous sheet such as paper or nonwoven fabric, or it can be cotton-like.

[0022] Anionic modified pulp is pulp infused with anionic groups, obtained by chemically modifying unmodified pulp. "Pulp" refers to cellulose fibers extracted from plant matter such as wood through mechanical and / or chemical treatment. The anionic groups are preferably incorporated into at least the surface of the pulp fibers.

[0023] Regarding plant-derived pulps, examples include: unbleached coniferous kraft pulp (NUKP), bleached coniferous kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), unbleached coniferous sulfite pulp (NUSP), bleached coniferous sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, and waste paper pulp. Any one of these can be used, or two or more can be used in combination.

[0024] Regarding the anionic groups, examples include at least one selected from the group consisting of carboxyl, phosphate, sulfate, sulfonic acid, nitrate, and borate groups. Preferably, at least one selected from the group consisting of carboxyl, phosphate, and sulfate groups is preferred. These anionic groups can be directly bonded to glucose units, which are the building blocks of the cellulose molecule, or indirectly bonded. In the case of indirect bonding, an alkylene group having one to four carbon atoms may be present, for example, between the glucose unit and the anionic group. The anionic group can be bonded to one or more glucose units constituting all of the cellulose molecule, or it can be bonded to one or more glucose units constituting only a portion of the cellulose molecule.

[0025] In one embodiment, examples of anionic modified pulp include oxidized cellulose fibers obtained by oxidizing the hydroxyl groups of glucose units in cellulose molecules, and carboxymethylated cellulose fibers obtained by carboxylating the hydroxyl groups of glucose units in cellulose molecules. For oxidized cellulose fibers, examples include those in which the C6 hydroxyl group of glucose units in cellulose molecules is selectively oxidized to a carboxyl group. Oxidized cellulose fibers are obtained by oxidizing natural cellulose such as wood pulp using a co-oxidizing agent in the presence of an N-oxygen radical (oxyl) compound. For the N-oxygen radical compound, compounds with nitric oxide radicals commonly used as oxidation catalysts can be used, such as piperidine nitric oxide radicals, particularly preferably 2,2,6,6-tetramethylpiperidine nitric oxide radical (TEMPO) or 4-acetamido-TEMPO. In a preferred embodiment, the anionic modified cellulose fiber is a TEMPO-oxidized cellulose fiber obtained by using TEMPO and oxidizing the cellulose.

[0026] In this embodiment, for anionic modified pulp, at least 45 mol% of its anionic groups are onium salts. That is, at least 45 mol% of the anionic groups have onium ions as counterions. By introducing at least 45 mol% of onium salts, the anionic modified pulp can be endowed with thermoforming properties (also known as thermo-softening properties), and can be thermoformed even without the presence of resins such as thermoplastic resins. The onium salt introduction rate is preferably 50 mol% or more of the anionic groups, more preferably 70 mol% or more, more preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol%.

[0027] The onium salt induction rate is calculated, for example, by using FT-IR when the anionic group is a carboxyl group, based on the absorption peak area originating from the onium salt and the absorption peak area originating from the anionic group of the acid form. In this case, if a metal salt is also present as another salt, the metal content is determined by ICP-based luminescence spectrophotometry. When the anionic group is a phosphate or sulfate group, the nitrogen content is measured using total nitrogen analysis to calculate the onium salt induction rate. Details regarding the onium salt induction rate are described in the Examples section.

[0028] The term "onium salt" here is used in a broad sense, encompassing not only salts of onium ions generated by the protonation of hydrides, but also salts of cations in which some or all protons of the onium ion are replaced by alkyl or aromatic groups. Examples of onium salts include ammonium salts, phosphonium salts, sulfonium salts, and oxonium salts. Ammonium salts and phosphonium salts are preferred. Any one of these can be used, or two or more can be used in combination. Here, "aromatic group" refers to a monovalent hydrocarbon group having an aromatic ring; examples include aryl or aralkyl groups.

[0029] Regarding ammonium salts, examples include: quaternary ammonium salts (e.g., tetramethylammonium salt, tetrabutylammonium salt, tetraoctylammonium salt, hexadecyltrimethylammonium salt, methyltrioctylammonium salt, tetradecylammonium salt, trimethyldodecylammonium salt, trimethyltetradecylammonium salt, trimethyltetradecylammonium salt, trimethyloctadecylammonium salt, tributyldodecylammonium salt, trioctylmethylammonium salt, tetra(dodecyl)ammonium salt, octyldimethylethylammonium salt, dodecyldimethylethylammonium salt, didecyldimethylammonium salt, etc., tetradecylammonium salts), benzyltributylammonium salt, benzyltripropylammonium salt, benzyltriethylammonium salt, benzyltrimethylammonium salt, benzyldimethyldodecylammonium salt, benzyldimethyldecylammonium salt, benzyldimethyldecylammonium salt, etc.). Ammonium salts containing aromatic groups, such as tetraalkylammonium salts, benzyl dimethyl octadecylammonium salt, 1-ethyl-3-methylimidazolium salt, dodecylpyridinium salt, 1-allyl-3-methylimidazolium salt, 1-butylpyridinium salt, 1-butyl-4-methylpyridinium salt, etc. (heterocyclic quaternary ammonium salts), tertiary ammonium salts (e.g., trialkylammonium salts such as trioctylammonium salt and trihexylammonium salt), secondary ammonium salts (e.g., dialkylammonium salts such as dioctylammonium salt, dibutylammonium salt, dihexylammonium salt, di(dodecyl)ammonium salt, distearylammonium salt), and primary ammonium salts (e.g., alkylammonium salts such as dodecylammonium salt, oleylammonium salt, stearylammonium salt, etc., and alkylammonium salts such as diethylene glycol ammonium salt).

[0030] Regarding phosphonium salts, examples include: quaternary phosphonium salts (e.g., tributylmethylphosphonium salt, tributyldodecylphosphonium salt, tributyltetradecylphosphonium salt, tributylhexadecylphosphonium salt, trihexyl(tetradecyl)phosphonium salt, tetraethylphosphonium salt, tetrabutylphosphonium salt, tetraoctylphosphonium salt, etc., tetraalkylphosphonium salts, tetraphenylphosphonium salt, benzyltriphenylphosphonium salt, methyltriphenylphosphonium salt, ethyltriphenylphosphonium salt, butyltriphenylphosphonium salt, tetradecyltriphenylphosphonium salt, etc., containing aromatic groups).

[0031] In addition, any one of the onium salts listed above can be used, or two or more can be used together.

[0032] Regarding onnnage salts, it is preferable that the modifier used to form onnnage salts from anionic groups has a melting point of 150°C or lower. By setting the melting point of the modifier to 150°C or lower, thermoformability can be further improved. The melting point of the modifier is preferably 100°C or lower, more preferably 50°C or lower, and even more preferably liquid at room temperature (25°C). The lower limit of the melting point is not particularly limited, for example, it can be -50°C.

[0033] Here, the term "modifier" refers to a compound that forms an onium salt together with an acidic anionic group. However, when the modifier is a quaternary onium salt, the "melting point" is defined as the melting point obtained by measuring the acetate salt after replacing the anion that forms the salt with the onium ion with an acetate ion. The melting point is determined by slowly increasing the temperature of the modifier using a melting point measuring device, and is taken as the temperature at which the modifier melts, as detailed in the Examples section.

[0034] Regarding ononium salts, quaternary ononium salts are preferred from the perspective of further improving thermoformability. For example, quaternary ammonium salts and / or quaternary phosphonium salts are preferred, and at least one selected from the group consisting of tetraalkylammonium salts, aralkyltrialkylammonium salts, and tetraalkylphosphonium salts is more preferred.

[0035] The amount of anionic groups measured after all anionic groups have been converted to the acidic form in the anionic modified pulp is preferably 0.5 to 3.0 mmol / g, more preferably 1.0 to 2.8 mmol / g, and even more preferably 1.5 to 2.5 mmol / g. As described above, the anionic modified pulp of the embodiment is a salt-type anionic modified pulp containing onium salts; therefore, when measuring the amount of anionic groups, all anionic groups are converted to the acidic form before measurement. The amount of anionic groups is the molar mass (mmol) of anionic groups per unit dry mass of the acidic anionic modified pulp, and can be measured by known methods. Specifically, it can be measured by the method described in the Examples section. In addition, in this specification, "dry mass" refers to the mass after drying at 140°C until the mass change rate per minute reaches 0.05% or less.

[0036] In the anionic modified pulp of this embodiment, the anionic group may be only an onium salt, or it may include onium salts and other salts. There are no particular limitations on the other salts; examples include alkali metal salts such as sodium and potassium salts, and alkaline earth metal salts such as magnesium and calcium salts. Furthermore, the anionic group need not all be salt-type (for example, -COOX when it is a carboxyl group (here, X is a cation that forms a salt with a carboxylic acid)), and it may include both onium-containing salt-type and acid-type groups (with H+ as the counter ion). + Also known as the H-type. For example, the carboxyl group is -COOH).

[0037] Anionic modified pulp, as described above, is obtained by chemically modifying unmodified pulp and is not defibrinated. In this respect, it can be distinguished from cellulose nanofibers obtained by micronizing pulp through defibrination. The fiber diameter of the anionic modified pulp is the same as that of the untreated pulp, varying depending on the raw pulp, but typically tens of μm. Specifically, the number-average fiber width of the anionic modified pulp is preferably 5 to 100 μm, more preferably 10 to 60 μm, and may also be 20 to 40 μm.

[0038] The number-average fiber width of anionic modified pulp was determined as follows: For an aqueous suspension of anionic modified pulp diluted to 0.01% by mass, 10 images were taken using an optical microscope, 25 fibers were selected from these images, and the width (diameter) of the fibers was measured. The arithmetic mean of the measured fiber width was then calculated.

[0039] The fibrous material for thermoforming in this embodiment can be composed solely of the aforementioned anionic modified pulp, or it can contain the aforementioned anionic modified pulp and additives as any component. Examples of additives include: colorants such as pigments or dyes, waterproofing agents, flame retardants, plasticizers, antioxidants, light stabilizers, fillers, and antistatic agents. As described above, the anionic modified pulp of this embodiment has thermoforming properties, therefore it can be thermoformed independently. Therefore, the fibrous material for thermoforming preferably does not contain resins such as thermoplastic resins, and can be thermoformed directly without adding resin.

[0040] The form of the fibrous material used for thermoforming in this embodiment is not particularly limited. For example, as described above, it can be a fibrous sheet such as paper or nonwoven fabric, or it can be cotton-like.

[0041] When forming fiber sheets, paper can be produced by using a suspension containing anionic modified pulp as the pulp material. Papermaking is the process of dewatering the pulp through filtration to form a sheet, and then pressing and drying it to produce paper. During papermaking, known papermaking machines such as long-wire wet papermaking machines, double-wire papermaking machines, Yankee papermaking machines, cylinder papermaking machines, and cylinder / short-wire composite papermaking machines can be used. Alternatively, a suspension containing anionic modified pulp can be filtered under reduced pressure to form a sheet, dried, and then pressed to produce fiber sheets. These pressing and drying processes are preferably carried out at a non-plasticizing temperature using anionic modified pulp. The thickness of the fiber sheet is not particularly limited; for example, it can be from 0.001 to 50 mm, or from 0.01 to 5 mm. Furthermore, in this specification, "sheet" and "sheet-like" respectively encompass the concepts of "film" and "film-like."

[0042] A molded body can be obtained by thermoforming the fibrous material. As described above, thermoforming refers to softening (plasticizing) the fibrous material by heating it to form a predetermined shape, and then solidifying it by cooling. Examples include thermoforming, vacuum forming, and air-forming. There are no particular limitations on the shape of the molded body; various shapes such as sheet material, plate material, and three-dimensional structures can be included. Specific examples of molded bodies include sheets, packaging materials, tableware (cups, plates, etc.), and containers (bottles, trays, etc.).

[0043] Normally, paper made from pulp has voids between the pulp particles, and is therefore opaque. However, with the fibrous material used for thermoforming in this embodiment, for example, by hot pressing, the fibers are tightly bonded together without gaps, the voids disappear, and transparency is achieved.

[0044] Furthermore, paper made from ordinary pulp does not bond even when multiple sheets are stacked and hot-pressed. However, if the paper is a fibrous sheet made of a thermoforming fibrous material according to this embodiment, by stacking multiple sheets and hot-pressing at least a portion of them, the fibrous sheets can bond together in the thermoformed portion and can be heat-sealed. Therefore, a heat-sealable fibrous sheet can be provided.

[0045] [Composite materials for thermoforming]

[0046] The thermoforming composite material of this embodiment comprises anionic modified pulp in which at least 45 mol% of the aforementioned anionic groups are onium salts, and a thermoplastic resin. Because the anionic modified pulp contains onium salts, it is easily softened and flowable upon heating, thus easily mixing with the molten thermoplastic resin and preventing the formation of agglomerates of the anionic modified pulp. Therefore, a molded article with excellent surface appearance and excellent thermoforming properties can be obtained.

[0047] There are no particular limitations on thermoplastic resins. Examples include: polyethylene (PE), polypropylene (PP), polyvinyl chloride, polystyrene, polyvinylidene chloride, fluoropolymers, (meth)acrylic resins, polyamide resins, polyester resins, polylactic acid, polycaprolactone, ABS resin, polycarbonate resin, polyphenylene ether, polyurethane, polyacetal, vinyl ether resin, polysulfone resins, etc. Any one of these can be used, or two or more can be used together.

[0048] The amount of anionic modified pulp in this thermoforming composite material is not particularly limited. For example, when using anionic modified pulp as a reinforcement for thermoplastic resin, it is preferable that the thermoplastic resin is the main component with the matrix as the main component, and the amount of anionic modified pulp can be from 0.5% to 50% by mass, or from 1% to 30% by mass. In this case, the amount of thermoplastic resin can be from 50% to 99.5% by mass, or from 70% to 99% by mass.

[0049] In this thermoforming composite material, additives can be included as any component along with anionic modified pulp and thermoplastic resin. Examples of additives include: colorants such as pigments or dyes, waterproofing agents, flame retardants, plasticizers, antioxidants, light stabilizers, fillers, and antistatic agents.

[0050] The manufacturing method of this thermoforming composite material is not particularly limited; for example, a method of mixing thermoplastic resin with anionic modified pulp at the melting temperature of thermoplastic resin can be listed. The form of the thermoforming composite material is not particularly limited; for example, sheet form, plate form, granular form, powder form, long fiber form, etc. can be listed.

[0051] A molded body can be obtained by thermoforming the composite material. Thermoforming refers to softening the composite material by heating it and shaping it into a predetermined shape, then solidifying it by cooling. Examples include thermoforming, vacuum forming, air forming, injection molding, extrusion molding, and FDM 3D printing. There are no particular limitations on the shape of the molded body; various shapes such as sheet material, plate material, and three-dimensional structures can be included. Specific examples of molded bodies include sheets, packaging materials, tableware (cups, plates, etc.), and containers (bottles, trays, etc.).

[0052] Example

[0053] The following describes in detail the relevant embodiments and comparative examples. However, the present invention is not limited to these embodiments.

[0054] The methods for determining the various physical properties in the examples and comparative examples are described below.

[0055] [Amount of anionic groups (carboxyl groups)]

[0056] Prepare 50 mL of an aqueous suspension of anionic modified acid pulp with a pulp concentration of 0.1% by mass, and adjust the pH to approximately 2.5 using a 0.1 mol / L hydrochloric acid aqueous solution. Then, add a 0.05 mol / L sodium hydroxide aqueous solution dropwise to the suspension and perform conductivity measurements until the pH reaches approximately 11. During the neutralization phase of the weak acid, where conductivity changes slowly, calculate the amount of carboxyl groups based on the amount of sodium hydroxide consumed (V) using the following formula.

[0057] Carboxyl group content (mmol / g) = V (mL) × [0.05 / mass of acid-type anion-modified pulp (g)]

[0058] [Amount of anionic groups (amount of phosphate groups)]

[0059] An aqueous suspension prepared by diluting anion-modified pulp with ion-exchanged water to a content of 0.2% by mass was treated with ion-exchange resin to form an acidic anion-modified pulp, which was then titrated with alkali for determination. For the ion-exchange resin treatment, 1 / 10 of a strong acidic ion-exchange resin (Ambergett 1024; Organo Co., Ltd., adjusted) was added to the aqueous suspension by volume, and the mixture was shaken for 1 hour. The ion-exchange resin was then separated from the aqueous suspension by injecting it through a 90 μm mesh sieve. The alkali titration involved adding 50 μL of 0.1 mol / L sodium hydroxide aqueous solution to the ion-exchange resin-treated aqueous suspension every 30 seconds while measuring the change in conductivity of the aqueous suspension. The amount of phosphate (mmol / g) is calculated by dividing the amount of alkali (mmol) required in the region corresponding to the first region of the measurement result by the amount of solids (g) in the aqueous suspension of the titrant.

[0060] [Amount of anionic groups (amount of sulfate groups)]

[0061] A predetermined amount of acid-type anionic modified pulp was burned, and the sulfur content in the combustion product was determined by combustion ion chromatography according to IEC 62321. The sulfur content was then converted into sulfuric acid content and calculated.

[0062] [Introduction rate of onium salt]

[0063] The sheets of fibrous materials for thermoforming obtained in Examples 1 to 18 and Comparative Examples 1 to 4 were determined by FT-IR. The absorption peak area derived from carboxylic acid (1720 cm⁻¹) was shown according to the following formula. -1 (nearby), and the absorption peak area derived from carboxylates (1600 cm⁻¹) -1 The induction rate of the onium salt was calculated. Furthermore, when a metal salt is included as another salt, the absorption peaks of the metal salt and the onium salt originate from the same location; therefore, the metal content was also determined and calculated using an ICP-based luminescence spectrophotometer.

[0064] Onionite salt incorporation rate [mol%] = {absorption peak area derived from carboxylate / (absorption peak area derived from carboxylate + absorption peak area derived from carboxylate)} × 100

[0065] For the thermoforming fibrous materials obtained in Examples 19 and 20, the nitrogen content was determined using a total nitrogen analyzer to calculate the induction rate of the onium salt.

[0066] [Melting point of the modifier]

[0067] The very hot liquid modifier (amine, phosphine, ammonium salt, phosphonium salt, etc.) was crushed in a mortar and placed into a melting point measuring tube. The melting point measuring tube was installed in a recess in the aluminum plate of the melting point measuring apparatus, and a glass cover was placed on top of it. The temperature of the melting point measuring apparatus was increased from 25°C at a rate of 5°C / min, and the melting point was determined at the temperature at which the modifier melted. Furthermore, for quaternary onium salt modifiers, the acetate salt was measured after replacing the anion that forms a salt with the onium ion with an acetate ion.

[0068] [Formability]

[0069] The sheets of fibrous material for thermoforming obtained in Examples 1 to 20 and Comparative Examples 1 to 4 were cut into 3cm long and 3cm wide to prepare test pieces. The test pieces were clamped in a stretching die and pressed at 100°C and 0.4MPa using a hot press. The resulting molded articles were observed and evaluated according to the following criteria.

[0070] A: A pressing time of less than 10 seconds can produce a molded body without wrinkles or cracks.

[0071] B: A pressing time of 11 seconds to 60 seconds can produce a molded body without wrinkles or cracks.

[0072] C: A pressing time of 61 seconds to 180 seconds can produce a molded body without wrinkles or cracks.

[0073] D: The sheet material cracked due to pressing, making it impossible to obtain a shaped part.

[0074] [Heat-sealable]

[0075] The sheets of fibrous material for thermoforming obtained in Examples 1 to 20 and Comparative Examples 1 to 4 were cut into 100 mm long and 15 mm wide sheets to prepare test pieces. Two test pieces were overlapped and pressed at 100°C and 0.1 MPa within a 10 mm long and 15 mm wide area using a hot press. Using a tensile testing machine, the unpressed ends were grasped and a T-shaped peel was performed at a tensile speed of 300 mm / min, and the maximum value was taken as the heat seal strength. The criteria for judging heat sealability are shown below.

[0076] A: For pressing time of less than 10 seconds and heat sealing strength of 0.1N / 15mm or higher.

[0077] B: For pressing time of 11 seconds or more but less than 60 seconds, and heat sealing strength of 0.1 N / 15 mm or more.

[0078] C: For pressing time of 61 seconds or more but less than 180 seconds and heat sealing strength of 0.1 N / 15 mm or more.

[0079] D: For those with a pressing time of 180 seconds, a heat seal strength of less than 0.1 N / 15 mm, or those that are not bonded.

[0080] [Transparency]

[0081] The fibrous materials obtained in Examples 1 to 20 and Comparative Examples 1 to 4 for thermoforming were cut into 3cm long and 3cm wide sheets to prepare test pieces. The test pieces were sandwiched between polyimide films and pressed using a hot press at 100°C and 0.4MPa for 5 minutes. The area of ​​the transparent portions of the pressed test pieces was measured using image analysis software. The criteria for determining transparency are shown below.

[0082] A: Over 50% transparency overall.

[0083] B: Overall transparency of 5% to less than 50%

[0084] C: The transparent area is less than 5% of the overall area.

[0085] [Surface appearance of the molded part]

[0086] The thermoforming composite materials obtained in Examples 21 to 22 and Comparative Example 5 were pressed at 200°C using a hot press and then cut to produce a film with a length of 5 cm, a width of 5 cm, and a thickness of 1 mm. The following shows the criteria for judging the surface appearance of the obtained film.

[0087] 〇: The number of agglomerates in the anion-modified pulp is less than 5.

[0088] ×: The anion-modified pulp has more than 5 agglomerates.

[0089] [Preparation of anion-modified pulps A1 to A5]

[0090] Before manufacturing the thermoforming materials for the examples and comparative examples, acid-type anionic modified pulps A1 to A5 used in these examples were prepared according to the following manufacturing examples 1 to 5.

[0091] [Manufacturing Example 1: Preparation of Anion-Modified Pulp A1 (TEMPO Oxidized Cellulose Fiber)]

[0092] Add 150 mL of water, 0.25 g of sodium bromide, and 0.025 g of TEMPO to 2 g of coniferous pulp, stir thoroughly to disperse, and then add a 13% (w / w) sodium hypochlorite aqueous solution (co-oxidant) relative to 1.0 g of the pulp to make the sodium hypochlorite concentration 10.0 mmol / g, and start the reaction. As the reaction proceeds, the pH decreases, so a 0.5 mol / L sodium hydroxide aqueous solution is added dropwise to maintain the pH at 10 to 11 while reacting until no pH change is observed (reaction time: 120 minutes). After the reaction is complete, add 0.1 mol / L hydrochloric acid to adjust the pH to 2.0, and then repeat filtration and washing to refine the pulp, obtaining cellulose fibers with oxidized fiber surfaces. Dilute with pure water to a cellulose fiber concentration of 4% (w / w) to prepare a TEMPO-oxidized cellulose fiber suspension. Then, after adjusting the pH of the pulp to 10 with a 24% (w / w) sodium hydroxide aqueous solution, add 0.2 mmol / g of sodium borohydride to the cellulose fibers to start the reaction. The reaction was carried out for 2 hours to achieve reduction. After the reaction, 0.1 mol / L hydrochloric acid was added to adjust the pH to 2.0, and the pulp was purified by repeated filtration and washing with water to obtain anionic modified pulp A1 with an acidic carboxyl group.

[0093] [Manufacturing Example 2: Preparation of Anion-Modified Pulp A2 (TEMPO Oxidized Cellulose Fiber)]

[0094] Except that the amount of sodium hypochlorite aqueous solution added to 1.0g of coniferous pulp was set to 6.0 mmol / g, anionic modified pulp A2 with acidic carboxyl groups was obtained by the same method as the preparation method of anionic modified pulp A1.

[0095] [Manufacturing Example 3: Preparation of Anionic Modified Pulp A3 (TEMPO Oxidized Cellulose Fiber)]

[0096] Except that the amount of sodium hypochlorite aqueous solution added to 1.0g of coniferous pulp was set to 4.0 mmol / g, anionic modified pulp A3 with acidic carboxyl groups was obtained by the same method as the preparation method of anionic modified pulp A1.

[0097] [Manufacturing Example 4: Preparation of Anionic Modified Pulp A4 (Phosphophosphated Cellulose Fiber)]

[0098] A mixed aqueous solution of ammonium dihydrogen phosphate and urea was added to 100 parts by weight of coniferous kraft pulp (absolute dry weight) to adjust the composition to 45 parts by weight of ammonium dihydrogen phosphate, 120 parts by weight of urea, and 150 parts by weight of water, thus obtaining a pulp impregnated with the solution. Next, the pulp impregnated with the solution was heated in a hot air dryer at 165°C for 200 seconds to introduce phosphate groups into the cellulose in the pulp, obtaining phosphoric acid esterified cellulose fibers. After the reaction, 0.1 mol / L hydrochloric acid was added to adjust the pH to 1.0, and the pulp was purified by repeated filtration and washing with water, thereby obtaining anionic modified pulp A4 with phosphoric acid esterification on the fiber surface and acidic phosphate groups.

[0099] [Manufacturing Example 5: Preparation of Anionic Modified Pulp A5 (Sulfated Cellulose Fiber)]

[0100] Mix 2g of coniferous kraft pulp, 20g of sulfamic acid, 50g of urea, and 100g of deionized water, and stir for 10 minutes. After stirring, filter the pulp using filter paper (No. 2). Filter until the solution no longer drips. After filtration, peel the pulp off the filter paper and place it in a dryer with the constant temperature bath set to 50°C for 6 hours. After the reaction, add 0.1mol / L hydrochloric acid to adjust the pH to 1.0, and then repeat filtration and washing to refine the pulp, thereby obtaining anionic modified pulp A5 with sulfated fiber surfaces and acidic sulfate groups.

[0101] [Example 1]

[0102] (Preparation of the modifier)

[0103] Tetrabutylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in ethanol to a concentration of 0.1N. Then, an ion exchange resin (manufactured by Tokyo Chemical Industry Co., Ltd., Amballight IRN78) was added in an amount five times that of the tetrabutylammonium bromide, and the mixture was stirred overnight in a shaker. The ion exchange resin was then removed by filtration to obtain a 0.1N tetrabutylammonium hydroxide ethanol solution.

[0104] (Introduction of onium salts)

[0105] Anionic modified pulp A1 was diluted with ethanol to 0.2% by mass, and then 0.1N tetrabutylammonium hydroxide ethanol solution was added in an equimolar amount equal to the carboxyl group content of anionic modified pulp A1. The mixture was stirred at room temperature for 2 hours. The pulp was then filtered through a nylon mesh filter with a mesh size of 59 μm. The residue remaining on the filter was diluted with ethanol and filtered again. This process was repeated three times to obtain anionic modified pulp B1.

[0106] (Sheet preparation)

[0107] The obtained anionic modified pulp B1 was diluted with ethanol to 0.2% by mass and then filtered under reduced pressure through a nylon mesh filter with a mesh size of 59 μm to obtain a sheet-like wet packing. After air drying at room temperature, it was clamped with a polyimide membrane and pressed at 0.1 MPa for 5 minutes at 20°C using a hot press to obtain a sheet (thermoforming fibrous material) of Example 1 with a thickness of 100 μm.

[0108] [Example 2]

[0109] Except for the use of tetraoctylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and onion salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B2. Using the obtained anionic modified pulp B2, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 2.

[0110] [Example 3]

[0111] Except for the use of benzyltributylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and onion salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B3. Using the obtained anionic modified pulp B3, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 3.

[0112] [Example 4]

[0113] Except for the use of hexadecyltrimethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and onion salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B4. Using the obtained anionic modified pulp B4, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 4.

[0114] [Example 5]

[0115] Except for the use of trihexyl(tetradecyl)phosphonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and onion salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B5. Using the obtained anionic modified pulp B5, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 5.

[0116] [Example 6]

[0117] Except for the use of tetraoctylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and onion salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B6. Using the obtained anionic modified pulp B6, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 6.

[0118] [Example 7]

[0119] (Introduction of onium salts)

[0120] Anionic modified pulp A1 was diluted with ethanol to 0.2% by mass, and then trioctylamine was added in an equimolar amount of carboxyl groups to anionic modified pulp A1. The mixture was stirred at room temperature for 2 hours. The pulp was then filtered through a 59 μm nylon mesh filter to obtain anionic modified pulp B7.

[0121] (Sheet preparation)

[0122] The obtained anionic modified pulp B7 was diluted with ethanol to 0.2% by mass and then filtered under reduced pressure through a nylon mesh filter with a mesh size of 59 μm to obtain a sheet-like wet packing. After air drying at room temperature, it was clamped with a polyimide membrane and pressed at 0.1 MPa for 5 minutes at 20°C using a hot press to obtain a sheet (fibrous material for thermoforming) of Example 7 with a thickness of 100 μm.

[0123] [Example 8]

[0124] Except for the use of dioctylamine, the onium salt was introduced in the same manner as in Example 7 to obtain anionic modified pulp B8. Using the obtained anionic modified pulp B8, sheets were prepared in the same manner as in Example 7 to obtain the sheet of Example 8.

[0125] [Example 9]

[0126] Except for the use of diethylene glycolamine (i.e., 2-(2-aminoethoxy)ethanol), the onium salt was introduced using the same method as in Example 7 to obtain anionic modified pulp B9. Using the obtained anionic modified pulp B9, sheets were prepared using the same method as in Example 7 to obtain the sheet of Example 9.

[0127] [Example 10]

[0128] Except for the use of 1-ethyl-3-methylimidazolium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), the modifier and the onium salt were prepared and introduced in the same manner as in Example 1 to obtain anionic modified pulp B10. Using the obtained anionic modified pulp B10, sheets were prepared in the same manner as in Example 1 to obtain the sheet of Example 10.

[0129] [Example 11]

[0130] Except for the use of anionic modified pulp A2, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B11. Using the obtained anionic modified pulp B11, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 11.

[0131] [Example 12]

[0132] Except for the use of anionic modified pulp A3, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B12. Using the obtained anionic modified pulp B12, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 12.

[0133] [Example 13]

[0134] Except for adding 0.9 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution of the carboxyl group amount of anionic modified pulp A1, the preparation of the modifier and the introduction of the onium salt were carried out in the same manner as in Example 2 to obtain anionic modified pulp B13. Using the obtained anionic modified pulp B13, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 13.

[0135] [Example 14]

[0136] Except for adding 0.75 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution of the carboxyl group amount of anionic modified pulp A1, the preparation of the modifier and the introduction of the onium salt were carried out in the same manner as in Example 2 to obtain anionic modified pulp B14. Using the obtained anionic modified pulp B14, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 14.

[0137] [Example 15]

[0138] Except for adding 0.5 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution to the anionic modified pulp A1, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B15. Using the obtained anionic modified pulp B15, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 15.

[0139] [Example 16]

[0140] Except for the addition of 0.5 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution and 0.5 molar amounts of 0.1N sodium hydroxide aqueous solution of the carboxyl group amount of anionic modified pulp A1, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B16. Using the obtained anionic modified pulp B16, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 16.

[0141] [Example 17]

[0142] Except for the addition of 0.1N tetraoctylammonium hydroxide ethanol solution (0.5 molar amounts of the carboxyl group amount of anionic modified pulp A1) and 0.1N benzyltributylammonium hydroxide ethanol solution (0.5 molar amounts of the carboxyl group amount of anionic modified pulp A1) (refer to Example 3), the modifier and onium salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B17. Using the obtained anionic modified pulp B17, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 17.

[0143] [Example 18]

[0144] Except for the addition of 0.1N tetraoctylammonium hydroxide ethanol solution (0.5 molar amounts of the carboxyl group amount of anionic modified pulp A1) and 0.1N hexadecyltrimethylammonium hydroxide ethanol solution (0.5 molar amounts of the carboxyl group amount of anionic modified pulp A1) (refer to Example 4), the modifier and onium salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B18. Using the obtained anionic modified pulp B18, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 18.

[0145] [Example 19]

[0146] Except for the use of anionic modified pulp A4, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B19. Using the obtained anionic modified pulp B19, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 19.

[0147] [Example 20]

[0148] Except for using anionic modified pulp A5, the modifier and onion salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp B20. Using the obtained anionic modified pulp B20, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Example 20.

[0149] [Comparative Example 1]

[0150] Anionic modified pulp A1 was diluted to 0.2% by mass with deionized water and then filtered under reduced pressure through a nylon mesh filter with a mesh size of 59 μm to obtain a sheet-like wet stockpile. After air drying at room temperature, it was clamped with a polyimide membrane and pressed at 0.1 MPa for 5 minutes at 20°C using a hot press to obtain a sheet of Comparative Example 1 with a thickness of 100 μm.

[0151] [Comparative Example 2]

[0152] Anionic modified pulp A1 was diluted to 0.2% by mass with deionized water and then neutralized with 0.1N sodium hydroxide aqueous solution to achieve a pH of 7.0 (25°C). It was then filtered through a 59μm mesh nylon mesh filter to obtain sodium salt-based anionic modified pulp C2. The obtained anionic modified pulp C2 was diluted to 0.2% by mass with ethanol and then filtered under reduced pressure through a 59μm mesh nylon mesh filter to obtain a sheet-like wet stock. After air drying at room temperature, it was clamped with a polyimide membrane and pressed using a hot press at 20°C and 0.1MPa for 5 minutes to obtain a sheet of Comparative Example 2 with a thickness of 100μm.

[0153] [Comparative Example 3]

[0154] Except for the addition of 0.4 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution and 0.6 molar amounts of 0.1N sodium hydroxide aqueous solution of anionic modified pulp A1, the modifier and onium salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp C3. Using the obtained anionic modified pulp C3, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Comparative Example 3.

[0155] [Comparative Example 4]

[0156] Except for adding 0.4 molar amounts of 0.1N tetraoctylammonium hydroxide ethanol solution to the anionic modified pulp A1, the modifier and onium salt were prepared and introduced in the same manner as in Example 2 to obtain anionic modified pulp C4. Using the obtained anionic modified pulp C4, sheets were prepared in the same manner as in Example 2 to obtain the sheet of Comparative Example 4.

[0157] For the sheets prepared in Examples 1 to 20 and Comparative Examples 1 to 4 above, the induction rate of onium salt was measured, and the formability, heat-sealing properties, and transparency were evaluated. The results are shown in Table 1.

[0158] [Table 1]

[0159]

[0160] As shown in Table 1, in Comparative Examples 1 and 2 without onion salt and Comparative Examples 3 and 4 with low onion salt incorporation rates, the anionic modified pulp lacks thermoforming properties, resulting in poor formability, heat-sealing properties, and transparency. In contrast, Examples 1 to 20, which incorporated a predetermined amount of onion salt, exhibit thermoforming properties and heat-sealing properties, enabling the transparentization of sheets. A higher onion salt incorporation rate is superior for formability, heat-sealing properties, and transparency. Furthermore, modifiers with lower melting points exhibit superior properties in these areas, and quaternary onion salts are superior to primary to tertiary onion salts in these properties.

[0161] [Example 21]

[0162] In contrast to 100 parts by weight of polycaprolactone, 2 parts by weight of absolutely dried anionic modified pulp B2 were mixed at 200°C and 100 rpm for 10 minutes using Laboplastil (manufactured by Toyo Seiki Co., Ltd.) to produce the thermoforming composite material of Example 21.

[0163] [Example 21]

[0164] Except for the use of polylactic acid instead of polycaprolactone, the thermoforming composite material of Example 21 was prepared in the same manner as in Example 21.

[0165] [Comparative Example 5]

[0166] In contrast to 100 parts by weight of polycaprolactone, 2 parts by weight of absolutely dried anionic modified pulp A1 were mixed at 200°C and 100 rpm for 10 minutes using Laboplastil (manufactured by Toyo Seiki Co., Ltd.) to produce a thermoforming composite material for Comparative Example 5.

[0167] The surface appearance of the thermoforming composite materials prepared in Examples 21, 22 and Comparative Example 5 was evaluated. The results are shown in Table 1.

[0168] [Table 2]

[0169]

[0170] As shown in Table 2, for the thermoforming composite material of Comparative Example 5, since it contains anionic modified pulp without the introduction of onion salt, multiple agglomerates can be seen on the surface of the thermoformed body. In contrast, for the thermoforming composite materials of Examples 21 and 22, since they contain anionic modified pulp that has been given thermoforming properties through the introduction of onion salt, the surface appearance of the thermoformed body is excellent.

[0171] Furthermore, the various numerical ranges described in this specification can be arbitrarily combined with their upper and lower limits, and all such combinations are described in this specification as preferred numerical ranges. Additionally, the description of the numerical range "X to Y" refers to X and below Y.

[0172] The foregoing has described some embodiments of the present invention, but these embodiments are shown as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments, or their omissions, substitutions, modifications, etc., are included in the same scope or spirit of the invention as described in the claims and their equivalents.

Claims

1. A fibrous material for thermoforming, characterized in that, Anionic modified pulp containing at least 45 mol% of onium salts as anionic groups.

2. The fibrous material for thermoforming as described in claim 1, wherein, The melting point of the modifier used to make the anionic group into an onium salt is below 150°C.

3. The fibrous material for thermoforming as described in claim 1, wherein, The ononium salt is a quaternary ononium salt.

4. The fibrous material for thermoforming as described in claim 1, wherein, The amount of anionic groups in the anionic modified pulp, determined by converting all anionic groups to the acidic form, is 0.5~3.0 mmol / g.

5. A molded body, characterized in that, It is thermoformed from any one of claims 1 to 4.

6. A composite material for thermoforming, characterized in that, It contains: anionic modified pulp in which at least 45 mol% of the anionic group is an onium salt, and thermoplastic resin.

7. A molded body, characterized in that, The composite material for thermoforming as described in claim 6 is thermoformed.

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