JP7781505B2 - Method for improving strength of resin-containing molded body - Google Patents

Description

The present invention relates to nanosized cellulose fibers obtained by defibrating cellulose fiber-containing materials derived from plants or microorganisms. The present invention also relates to molded articles obtained by molding a composition containing nanosized cellulose fibers and a resin, wood boards obtained by molding a composition containing nanosized cellulose fibers and a wood raw material, and foods and beverages to which nanosized cellulose fibers have been added.

Cellulose is an abundant biological polymer, and there are high expectations for its potential applications. For example, wood is a carbon-neutral material that contains a large amount of plant-derived cellulose and can be reproduced and used sustainably, making its effective use an extremely important issue.

Residues remaining after extracting or squeezing beverage components from plants (hereinafter, these may be collectively referred to as "beverage production residues") are rich in cellulose fibers. Beverage production residues, such as used tea leaves, coffee grounds, and vegetable residues, have been steadily increasing in recent years, and although they have traditionally been treated as industrial waste, methods for reusing them have also been proposed.
For example, it has been proposed to finely grind used tea leaves or coffee extraction residue, mix them with a binder material such as a thermoplastic resin or a biodegradable resin, and mold them into packaging materials in the form of pellets, sheets, etc. (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2000-281917

When considering the usability of the above-mentioned materials containing cellulose fibers, wood has the problems of not having sufficient dimensional stability and being difficult to mold freely.
On the other hand, beverage manufacturing residues such as used tea leaves are often mixed with other materials for use, but dispersibility can sometimes be an issue.
Thus, the effective utilization of materials containing cellulose fibers remains a challenge.

The purpose of this invention is to find a way to more effectively utilize cellulose fibers and to develop new applications.

In an effort to solve the above problems, we conducted research and discovered that defibrating cellulose fiber-containing materials to an average fiber diameter of 4 to 3,000 nm results in excellent dispersibility, making it easier to use when added to resins or wood-based raw materials, and allowing it to be added to foods and beverages to adjust their properties, leading to the completion of the present invention. Specifically, the present invention is as follows:

[1] Nanocellulose fibers obtained by defibrating a cellulose fiber-containing material derived from a plant or microorganism to an average fiber diameter of 4 to 3,000 nm.
[2] The nanosized cellulose fibers according to [1], wherein the cellulose fiber-containing material is a beverage production residue.
[3] The nanocellulose fiber according to [2], wherein the beverage production residue is tea leaves.
[4] A resin-containing molded body obtained by molding a composition containing the nanosized cellulose fibers according to any one of [1] to [3] and a resin.
[5] A wood board formed from a composition containing the nanocellulose fibers according to any one of [1] to [3] and a wood raw material.
[6] A pallet formed from the resin-containing molded body according to [4] or the wood board according to [5].
[7] A food or drink containing the nanocellulose fiber according to any one of [1] to [3].
[8] The food or drink according to [7], which is a liquid food or drink.

According to the present invention, nano-sized cellulose fibers are produced by defibrating cellulose fiber-containing materials to an average fiber diameter of 4 to 3,000 nm, allowing for more effective use of cellulose fibers and providing new applications.

The following describes an embodiment of the present invention.

[Nanocellulose fiber]
The cellulose fibers according to this embodiment are obtained by defibrating a cellulose fiber-containing material derived from a plant or microorganism so that the average fiber diameter is 4 to 3,000 nm. Hereinafter, such cellulose fibers will be referred to as "nanosized cellulose fibers."

Cellulose fiber-containing materials that can be used as raw materials for nanocellulose fibers include plants (e.g., wood, bamboo, hemp, pulp obtained from these, recycled pulp, etc.). In addition, oil cakes obtained after extracting vegetable oil from soybeans, rapeseed, palm, etc., and sugar cakes obtained after extracting sugar from sugar beets, cane, etc. may also be used.
Furthermore, as the cellulose fiber-containing material, cellulose fibers biosynthesized by microorganisms such as acetic acid bacteria (Acetobacter) can also be used.

In this embodiment, the cellulose fiber-containing material used as the raw material may be the residue remaining after extracting or squeezing beverage components from a plant (hereinafter, sometimes collectively referred to as "beverage production residue").
Examples of plants that can be used as raw materials for extraction include tea leaves, coffee beans, barley seeds, buckwheat seeds, etc. Examples of plants that can be used as raw materials for squeezing juice include various fruits and vegetables.
In particular, used tea leaves, which are the residue left after extracting tea components from tea leaves, contain functional components such as catechins in addition to cellulose fibers, and these can be used together with nanosized cellulose fibers. Therefore, adding nanosized cellulose fibers obtained from used tea leaves to produce resin-containing molded bodies, wooden boards, food and beverages, etc., as described below, can impart functions derived from used tea leaves to these products, making this method particularly suitable.

In this embodiment, chemically modified cellulose fibers may be used. Examples of chemically modified cellulose fibers include carboxymethylated cellulose and carboxylated cellulose.

The above-mentioned cellulose fiber-containing materials may be used alone or in combination of two or more types.

Examples of the treatment for nano-sizing the cellulose fiber-containing material include mechanical treatment, oxidation treatment, enzyme treatment, acid treatment, etc. Examples of the mechanical treatment include grinding and beating using a refiner, high-pressure homogenizer, microfluidizer, grinder, twin-screw kneader, etc.
An example of an oxidation treatment is the TEMPO method. This method uses 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) as a catalyst to selectively oxidize (carboxylate) the 6-hydroxyl groups in the amorphous regions of cellulose fibers, thereby increasing the repulsion between cellulose fibers. Alternatively, cellulose fibers can be hydrolyzed using enzymes (cellulase) or acids (sulfuric acid, hydrochloric acid, etc.). Cellulose fibers that have undergone these treatments can be easily defibrated using ultrasonic treatment or stirring, making it easy to obtain nano-sized cellulose.
Alternatively, an underwater counter-collision method may be employed in which aqueous dispersions are collided with each other.

The nanocellulose fibers obtained as described above preferably have an average fiber diameter of 3,000 nm or less, more preferably 500 nm or less. The average fiber diameter may be 100 nm or less, or may be 30 nm or less. When the upper limit of the average fiber diameter is within the above range, excellent dispersibility is achieved.
On the other hand, the average fiber diameter of the nanosized cellulose fibers may be 4 nm or more, or 10 nm or more.

These nano-sized cellulose fibers have excellent dispersibility, making them easy to use when added to resins or wood-based raw materials. Furthermore, their excellent dispersibility makes it possible to adjust the properties of the food and beverage products to which they are added.

[Resin-containing molded body]
The resin-containing molded body according to this embodiment is obtained by molding a composition containing the nanosized cellulose fibers and a resin.

The resin used in this embodiment may be a thermoplastic resin, a thermosetting resin, or the like, and any of these may be used.
The thermoplastic resin is not particularly limited, and examples thereof include polyolefin resins such as polypropylene resins and polyethylene resins; polystyrene resins; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; vinyl chloride resins such as vinyl chloride, ethylene-vinyl chloride copolymer, and chlorinated vinyl chloride copolymer; polycarbonate resins; and polylactic acid resins.
Examples of thermosetting resins include epoxy resins, thermosetting unsaturated polyester resins, phenolic resins, melamine resins, urea resins, alkyd resins, and polyurethanes.

In the above composition, the content of nanosized cellulose fibers is not particularly limited as long as it is within a range that does not impair the effects of the nanosized cellulose fibers. For example, it may be 1 to 100 parts by mass, 3 to 50 parts by mass, or 5 to 20 parts by mass per 100 parts by mass of the above resin.

In addition to the nanocellulose fibers and resin, the composition may contain various additives such as pigments, dyes, flame retardants, plasticizers, antistatic agents, lubricants, and fillers. Examples of pigments include titanium dioxide and carbon black. Examples of fillers include organic materials such as melamine resin, inorganic materials such as fumed silica, and metal materials such as nickel particles.

The resin composition can be produced by mixing the above components. Generally, a mechanical (melt) kneading method (melt and knead for thermoplastic resins) is used, using a single-screw extruder, twin-screw extruder, Henschel mixer, Banbury mixer, various kneaders, Brabender, calendar roll, etc.

The resin-containing molded article according to this embodiment can be produced by (melting) kneading the resin composition and molding it using a molding machine. Known molding methods can be used. Examples include extrusion molding, injection molding, blow molding, press molding, calendar molding, T-die molding, inflation molding, compression molding, pipe extrusion molding, laminate molding, and vacuum molding.

The resin-containing molded article obtained in this manner has excellent strength due to the inclusion of nanosized cellulose fibers. Furthermore, if the nanosized cellulose fibers are obtained from plants, functional components derived from the plants (examples include polyphenols such as catechin) are also included, which allows the resin-containing molded article to be endowed with various functions derived from the functional components, such as deodorizing and antibacterial functions.

Therefore, the resin-containing molded article of this embodiment can be suitably used for, for example, transport materials, building materials, housings, and the like.
Examples of applications for transport materials include pallets, containers, flexible containers, dollies, trays, and other transport materials.
Examples of building material applications include furniture such as desks and chairs; and building materials for homes such as interior and exterior wall materials, roofing materials, tiles, and doors.
Examples of applications for housings include housings for electrical products such as electronic devices and home appliances; and containers and packaging materials for food products and miscellaneous goods.
Among these, a pallet is one of the most suitable embodiments.

[Wood board]
The wood board of this embodiment is formed by molding a composition containing the nano-sized cellulose fibers and a wood raw material.

In this embodiment, wood boards include fiberboards, particle boards, wood wool cement boards, and wood chip cement boards.

The wood raw material can be so-called wood, which is generally used as a building material or structural material, etc. When used as a raw material for fiberboard, it may be in the form of a slurry or a preparable fibrous or powder form, and when used as a raw material for particleboard, it may be in the form of small pieces of wood.
Examples of tree species for the wood raw material include conifers such as cedar, cypress, hiba, larch, and pine; broad-leaved trees such as chestnut, birch, oak, castanopsis, poplar, and willow; and tropical woods such as lauan. However, any tree species can be used, and pulp obtained from these tree species can also be used. Wood waste, such as industrial waste and construction waste, is inexpensive and can therefore be suitably used as the wood raw material. Waste paper, also inexpensive, can also be suitably used as the wood raw material.

Fiberboards are obtained by steaming and defibrating wood raw materials (for example, wood chips and other wood waste materials) to obtain a wood fiber slurry, which is then molded (formed), and can be classified into hardboard (hard fiberboard), medium density fiberboard (MDF), insulation board (soft fiberboard), etc., depending on the presence or absence and degree of heat and pressure used during molding. Paper materials obtained by molding pulp are also included.
In this embodiment, by adding the nano-sized cellulose fibers to the wood fibers during molding, a fiberboard with improved strength can be obtained.

Particleboard is produced by adding adhesives to small pieces of wood (particles, chips, wood cuttings, crushed pieces, etc.), piling them into a predetermined shape, and then molding them under heat and pressure. In this embodiment, nanosized cellulose fibers are added, but they may be mixed with adhesive in advance and then the mixture with the adhesive added to the wood pieces, or they may be added to the wood pieces separately from the adhesive.

The wood board obtained in this manner has excellent strength due to the inclusion of nano-sized cellulose fibers. Furthermore, if the nano-sized cellulose fibers are obtained from plants, functional components derived from the plants (such as polyphenols such as catechin) are also included, which allows the wood board to be endowed with various functions derived from the functional components, such as deodorizing and antibacterial properties.

Therefore, the wooden board of this embodiment can be suitably used for transporting materials, building materials, enclosures, and the like.
Examples of applications for transport materials include pallets, containers, flexible containers, dollies, trays, and other transport materials.
Examples of building material applications include furniture such as desks and chairs; and building materials for homes such as interior and exterior wall materials, roofing materials, tiles, and doors.
Examples of housing applications include containers and packaging materials for food products, miscellaneous goods, etc.
Among these, when the wooden board is a hardboard, particle board, or the like, a pallet is one of the particularly suitable embodiments.
Furthermore, when various functions are imparted to the wood board, it is also suitable for use as a building material or a housing.

[Food and beverages]
The food and drink according to this embodiment is prepared by adding the nanosized cellulose fiber according to the above embodiment.

By blending nanosized cellulose fiber, which has excellent dispersibility, into the food and beverage products of this embodiment, it is possible to adjust properties such as the viscosity and shape retention of the added food and beverage products. Furthermore, if the nanosized cellulose fiber is obtained from a plant, functional components derived from the plant (examples include polyphenols such as catechin) are also blended in, thereby imparting various physiological activities derived from the functional components to the food and beverage products.

Nano-sized cellulose fibers have excellent dispersibility, can adjust viscosity, and can improve shape retention, making them suitable for a wide range of solid and semi-solid foods and beverages, including desserts such as yogurt, jelly, pudding, and mousse; frozen and frozen desserts such as ice cream and sorbet; baked and steamed confectioneries, including Western and Japanese sweets such as cakes and buns; creams such as buttercream and fresh cream; and jams such as strawberry jam and marmalade.

Furthermore, a particularly preferred aspect of the food and beverage of this embodiment is that it is a liquid food and beverage. By making it into a liquid food and beverage, the excellent dispersibility of the nanosized cellulose fiber makes it possible to adjust the viscosity and texture of the liquid food and beverage. Furthermore, since the functional ingredients derived from the plant body, which is the raw material for the nanosized cellulose fiber, are blended with good dispersibility, it is possible to impart various physiological activities derived from the functional ingredients to the food and beverage. Furthermore, even when the liquid food and beverage contains ingredients that are prone to precipitation, aggregation, separation, etc., the incorporation of nanosized cellulose fiber improves dispersibility. Furthermore, if the ingredient that is prone to precipitation, aggregation, separation, etc. is plant fiber, for example, it is possible to replace some or all of this with nanosized cellulose fiber, resulting in excellent handling and handling of the liquid food and beverage ingredients.

Liquid foods and beverages are not particularly limited, but examples include fruit or vegetable drinks including citrus juice and vegetable juice; soft drinks such as sports drinks; coffee drinks; tea-based drinks such as black tea and matcha; dairy drinks such as cocoa and lactic acid bacteria drinks; soups; and seasonings such as sauces and dressings.

The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

The present invention will be explained in more detail below by showing production examples, test examples, etc., but the present invention is not limited to the following production examples, test examples, etc.

[Production of nanocellulose fibers]
(Example 1-1)
Cellulose fiber (Ceolas, manufactured by Asahi Kasei Corporation) made from pulp was nano-processed using a high-pressure homogenizer.
(Example 1-2)
In addition, used tea leaves (manufactured by Ito En Co., Ltd.), which are the extraction residue of tea beverages, were subjected to nano-processing using a high-pressure homogenizer in the same manner as in Example 1.

The nano-sized cellulose fiber of Example 1-1 had extremely good dispersibility compared to Ceolus (Comparative Example 1), which was not subjected to nano-processing. Furthermore, the nano-sized cellulose fiber derived from used tea leaves of Example 1-2 had extremely good dispersibility, similar to Example 1-1.

[Production and Evaluation of Resin-Containing Molded Articles]
(Example 2-1)
100 parts by mass of polypropylene resin and 10 parts by mass of the nanosized cellulose fiber of Example 1-1 were melt-kneaded and formed into pellets to obtain a resin-containing composition. This resin-containing composition was then injection-molded to produce a pallet.
(Example 2-2, Comparative Example 2)
Pallets were obtained in the same manner as in Example 2-1, except that the nanosized cellulose fibers of Example 1-1 were replaced with the nanosized cellulose fibers derived from used tea leaves of Example 1-2 or the non-nanosized cellulose fibers of Comparative Example 1 (Example 2-2, Comparative Example 2-1). Furthermore, a pallet was produced by injection molding polypropylene resin without blending the cellulose fibers (Comparative Example 2-2).

The strain, deflection rate, and residual deflection rate of the obtained pallets of the example and comparative example were measured in accordance with JIS Z 0602. It was confirmed that the pallets of Example 2-1 and Example 2-2 had improved strength compared to the pallets of Comparative Examples 2-1 and 2-2.

[Production and evaluation of packaged tea beverages]
Example 3
20 g of green tea leaves (Yabukita variety) for extract were extracted with 700 mL of hot water (85°C) for 5 minutes and 30 seconds, and then insoluble matter was removed using a centrifuge to obtain a green tea leaf extract. Tencha was also ground in a stone mill to obtain powdered tea.
900 g of green tea leaf extract, 50 g of powdered tea, and 10 g of nanocellulose fiber derived from used tea leaves from Example 1-2 were blended and made up to 1000 mL with distilled water. The resulting mixture was UHT sterilized (135°C, 30 seconds), cooled to 85°C in a plate, filled into a transparent plastic container (PET bottle), and immediately cooled to 20°C to obtain a bottled green tea beverage.
(Comparative Example 3)
A packaged green tea beverage was produced in the same manner as in Example 3, except that the nano-sized cellulose fiber derived from used tea leaves of Example 1-2 was not added and the contents were filled up to the measuring point.

The resulting packaged green tea beverages of Example 3 and Comparative Example 3 were stored at 4°C for two weeks. Settling of the powdered tea was observed at the bottom of the container in the packaged green tea beverage of Comparative Example 3, but no settling of the powdered tea was observed in the packaged green tea beverage of Example 3.

Claims (2)

A method for improving the strength of a pallet formed from a resin-containing molded body (excluding wood boards containing wood chips), comprising:
Nano-sized cellulose fibers obtained by defibrating a cellulose fiber-containing material derived from a plant body or a microorganism so that the average fiber diameter is 4 to 3000 nm, wherein the cellulose fiber-containing material is a beverage production residue, and the beverage production residue is tea leaves; and
A method for improving the strength of a pallet, comprising forming the pallet from a resin-containing molded article obtained by molding a composition containing a resin (excluding polyalkene having a carboxy group) . A method for manufacturing a pallet having improved strength formed from a resin-containing molded body having improved strength (excluding wood boards containing wood chips), comprising:
Nano-sized cellulose fibers obtained by defibrating a cellulose fiber-containing material derived from a plant body or a microorganism so that the average fiber diameter is 4 to 3000 nm, wherein the cellulose fiber-containing material is a beverage production residue, and the beverage production residue is tea leaves; and
A method for producing a pallet with improved strength, comprising forming a pallet from a resin-containing molded article obtained by molding a composition containing a resin (excluding polyalkene having a carboxy group) .