JP2016008305A - Plasticized cellulose and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a plasticized cellulose capable of suppressing thermal decomposition (burning) of a cellulose material and to provide a plasticized cellulose obtained by the method.SOLUTION: There are provided: a method for producing a plasticized cellulose which comprises a step of subjecting a cellulose material to an ultrasonic treatment under pressure treatment; and a plasticized cellulose obtained by the method, wherein it is preferred that the press pressure in the pressure treatment is 1 to 1000 N/mm, the frequency of the ultrasonic wave is 10 to 50 kHz, the output is 500 to 3000 W and the treatment time for the ultrasonic treatment is 0.1 to 2 seconds.

Description

  The present invention relates to plasticized cellulose and a method for producing the same. Specifically, the present invention relates to a method for producing plasticized cellulose using mechanical treatment, and plasticized cellulose produced using the method.

  In recent years, research and development for using renewable and non-edible woody biomass as energy and new materials has been actively conducted around the world with the aim of building a recycling-oriented social system. Although the interest in cellulose, which is the most abundant biomass on the earth, is particularly high, cellulose does not exhibit thermoplasticity, and has disadvantages that cannot be handled by general plastic processing methods. It has become one.

  The reason why cellulose does not exhibit thermoplasticity is that it forms a strong network of hydrogen bonds within and between molecules. When trying to break hydrogen bonds by thermal treatment, thermal decomposition occurs before the cellulose melts (Non-Patent Documents 1, 2, 3, 4).

  For this reason, in order to plasticize cellulose and process it into a film or molded product, it has long been carried out to suppress hydrogen bonding by chemically modifying the hydroxyl group of cellulose. Typical examples are nitrification and nitration. However, chemical modification of the hydroxyl group of cellulose causes a problem that various physical properties such as crystallinity, mechanical strength, solvent resistance, and biodegradability change.

  On the other hand, the use of regenerated cellulose known as rayon, tencel, lyocell, etc. has long been performed as a method for molding cellulose. However, rayon obtained by a method in which a hydroxyl group of cellulose is chemically modified and dissolved in a solvent and then subjected to a molding process and elimination of the modifying group causes a decrease in physical properties due to a change in molecular structure or a decrease in molecular weight. In addition, tencel lyocell obtained by a method in which cellulose is directly dissolved in a solvent to perform molding processing and solvent distillation requires a high-temperature dissolution step for a long time, so that the physical properties are lowered similarly to rayon.

  In order to solve these problems, various ionic liquids capable of dissolving cellulose at a low load have been proposed, but there are disadvantages such as high solution viscosity and poor workability, ionic liquids themselves are expensive and poor in versatility. Yes (Patent Documents 1 and 2). Furthermore, since any of the above methods requires a plurality of large-scale facilities such as dissolution in a solvent, solvent distillation after processing, and solvent recovery, development of a more economical technique is required.

  Therefore, as a technique for plasticizing cellulose by mechanical treatment, a method of irradiating laser while simultaneously applying pressure, shear and thermal energy to cellulose is disclosed (Patent Document 3, Non-Patent Document 5). .

JP 2008-50595 A International Publication No. 2012/077798 US Pat. No. 7,901,612 B2

Ullmann's encyclopedia of industrial chemistry, 5th edition, vol. A5, 38, 1986 Das Papier, 44, 12, 617-624, 1990 TAPPI Journal, 67, 12, 82/83, 1984 Journal of Applied Polymer Science, 37, 3305-3314, 1989. Cellulose, 12, 159-165, 2005

  However, in the case of the mechanical treatment disclosed in Patent Literature 3 and Non-Patent Literature 5, it is impossible to obtain a large-area or large-volume plasticized cellulose, and the occurrence of thermal decomposition (burning) due to laser treatment is suppressed. There is a problem that it is difficult.

  Then, an object of this invention is to provide the manufacturing method of the plasticized cellulose which can suppress the thermal decomposition (burn) of a cellulose material, and the plasticized cellulose obtained by this method.

  As a result of intensive investigations, the present inventors have adopted ultrasonic treatment instead of laser treatment, and by pressing the cellulose material during ultrasonic treatment, so that thermal decomposition (burning) in the cellulose material is achieved. It has been found that the generation of water can be suppressed and a sufficiently plasticized cellulose can be obtained.

The present invention provides the following [1] to [6].
[1] A method for producing plasticized cellulose, comprising subjecting a cellulose material to ultrasonic treatment under press treatment.
[2] The manufacturing method according to [1], wherein a press pressure in the press treatment is 1-1000 N / mm ² .
[3] The method according to [1] or [2], wherein the frequency of the ultrasonic treatment is 10 to 50 kHz.
[4] The production method according to any one of [1] to [3], wherein an ultrasonic wave output in the ultrasonic treatment is 500 to 3000 W.
[5] The manufacturing method according to any one of [1] to [4], wherein a treatment time of the ultrasonic treatment is 0.1 second to 2 seconds.
[6] A plasticized cellulose obtained by the production method according to any one of [1] to [5].

  According to the present invention, plasticized cellulose can be obtained while suppressing thermal decomposition (burning) of a cellulose material.

  The reason why the cellulose material can be plasticized without causing thermal decomposition (burning) according to the present invention is that the energy exceeding the binding energy of cellulose hydroxyl group as described in Non-Patent Document 5 is mild. This is presumed to be possible.

  If this invention is used, a cellulose material can be plasticized easily and economically using a general installation. The shape of the plasticized cellulose is not particularly limited, and may be any shape such as a film, a sheet, a fiber, and a molded product in accordance with the use.

FIG. 1 is a diagram showing an X-ray profile of a sample of Example 1. FIG. 2 is a photograph of a sample of Example 1. FIG. 3 is a photograph of the sample of Comparative Example 1. FIG. 4 is a photograph of a sample of Comparative Example 3.

  In the present invention, the cellulose material is a material using cellulose as a raw material. Examples of cellulose include materials derived from cellulose such as wood-derived pulp (wood pulp), non-wood-derived pulp (non-wood pulp), bacterial cellulose, and squirt cellulose. Cellulose may be a molded body such as pulp, a sheet containing cellulose, or a film. Since the economy is high and the effect of the present invention is remarkable, the cellulose preferably contains wood pulp, more preferably wood pulp.

  Wood pulp includes red pine, black pine, todomatsu, spruce, beech pine, fir, tsuga, cedar, cypress, larch, syringe, spruce, hiba, douglas fir, hemlock, white fur, spruce, balsam fur, cedar, pine, merck pine, Pulp derived from conifers such as radiata pine; Pulp derived from a mixture of two or more selected from these conifers; Pulp derived from broad-leaved trees such as mangrove, lawan, and acacia, and pulp derived from two or more mixed materials selected from the broad-leaved trees; pulp derived from two or more mixed materials selected from these conifers and broad-leaved trees Illustrated.

  Examples of non-wood pulp include non-wood-derived pulps such as cotton, rayon, hemp, sisal hemp, manila hemp, flax, straw, bamboo, bagasse, kenaf and the like. Non-wood pulp and wood pulp may be used in combination as the cellulose material.

  It does not specifically limit as a method of pulping a wood raw material and / or a non-wood raw material. Examples of pulps obtained by pulping methods generally used in the paper industry include chemical pulps pulped by digestion using methods such as the kraft method, sulfite method, soda method, and polysulfide method; refiners, grinders, etc. Examples include mechanical pulp pulped by mechanical force; semi-chemical pulp pulped by mechanical force after chemical pretreatment; waste paper pulp; deinked pulp and the like. The pulp may be unbleached (before bleaching) or bleached (after bleaching). Either a pulp after beating or an unbeaten pulp may be used, but a beating pulp is preferable. Thereby, the intensity | strength of plasticized cellulose can be improved.

  In the present invention, the cellulose material is preferably a cellulose, such as pulp, formed into a sheet, film, roll or the like, and a sheet obtained by forming pulp mainly composed of wood pulp into a sheet with a paper machine. More preferred. In addition, when shape | molding a pulp into a sheet form, the additive generally used by the papermaking use may be added to a pulp. Examples of such additives include paper strength enhancers, bulking agents, pigments, yield improvers, freeness improvers, internal additive sizing agents (such as rosin sizing agents and sulfuric acid bands), pH adjusters, antifoaming agents, and pitch controls. Agents, slime control agents and the like. The amount of the additive used is not particularly limited as long as the effect of the present invention is not impaired. The cellulose material may contain other materials such as rayon fibers and films, and the other materials may be formed together with cellulose into the shape of a sheet, film, roll or the like.

  Examples of the paper machine include a long paper machine, a round paper machine, a gap former, a hybrid former, a multi-layer paper machine, and a known paper machine that combines two or more paper machines selected from these. Is mentioned. What is necessary is just to set the press linear pressure in a papermaking machine, and the calendar linear pressure in the case of performing a calendar process in the latter stage in the range which does not cause trouble in operativity and the performance of the plasticized cellulose obtained.

  Physical properties such as basis weight, density and thickness of the cellulose material used in the present invention can be freely selected according to the purpose of use.

  The thickness of the cellulose material is preferably 10 μm or more, and more preferably 20 μm or more. Thereby, the nonuniformity of a sheet | seat and a strength fall can be suppressed. Moreover, desired strength can be obtained after plasticization, and breakage during ultrasonic treatment can be suppressed. Furthermore, since it is possible to suppress the distance between the horn and the supporting metal jig from being too close during ultrasonic processing, stable ultrasonic processing can be performed. The upper limit of the thickness is preferably 2 mm or less, and more preferably 1.5 mm or less. Thereby, the continuous processing of ultrasonic processing can be performed easily. That is, ultrasonic treatment can be easily and continuously performed while a pulp molded sheet is fed at a constant speed between a horn and a supporting metal jig to which a certain pressing pressure is applied. The thickness of the cellulose material is preferably 10 μm to 2 mm, more preferably 20 μm to 1.5 mm.

  The water content of the cellulose material is preferably about 10 wt% or less. The cellulose material has a water content of about 10 wt% or less. The cellulose material may be a material generally called a dry sheet, or may be a material generally called a wet sheet containing excessive water or the like. The former is preferable. Thereby, since it can suppress that the energy provided by an ultrasonic wave and a press process volatilizes components, such as water, the efficiency fall of plasticization of a cellulose material can be suppressed.

  In the present invention, the cellulose material is subjected to ultrasonic treatment. The ultrasonic treatment is a treatment for irradiating ultrasonic waves. For ultrasonic treatment, an ultrasonic treatment apparatus is usually used. The ultrasonic processing apparatus may be a kind of apparatus generally called an ultrasonic plastic welding machine. For example, apparatuses such as a plastic welding machine made by Rinko and an ultrasonic welding machine made by Herman are exemplified. The former is suitable for intermittently obtaining a certain shape of plasticized cellulose, and the latter is suitable for obtaining a film or sheet of plasticized cellulose.

  The frequency with which the cellulose material is irradiated during the ultrasonic treatment is not particularly limited, but is preferably 10 kHz or more, and more preferably 20 kHz or more. Thereby, thermal decomposition of the cellulose material can be prevented. The upper limit is preferably 50 kHz or less, and more preferably 35 kHz or less. Thereby, cellulose can be easily plasticized. The frequency is preferably 10 kHz to 50 kHz, more preferably 20 kHz to 35 kHz.

  The output of the ultrasonic wave used for the ultrasonic treatment is preferably 500 W or more, and more preferably 800 W or more. Thereby, cellulose can be easily plasticized. The upper limit is preferably 3000 W or less, and more preferably 2000 W or less. Thereby, thermal decomposition of a cellulose material can be prevented. The output of the ultrasonic wave is preferably 500 to 3000 W, and more preferably 800 to 2000 W.

The ultrasonic treatment is performed under press treatment. The press pressure in the press treatment is not particularly limited, but is preferably 1 N / mm ² or more, and more preferably 5 N / mm ² or more. The upper limit is preferably 1000 N / mm ² or less, and more preferably 500 N / mm ² or less. Thereby, plasticization of a cellulose material can be performed more stably and thermal decomposition can be suppressed. Pressing pressure is preferably ^{1N / mm 2 ~1000N / mm 2} , more preferably ^{5N / mm 2 ~500N / mm 2} . Although the aspect of a press process is not specifically limited, Usually, a cellulose material is pressed between a horn and a support metal jig.

  In the present invention, the treatment time of the ultrasonic treatment is preferably 0.1 seconds or more, and preferably 0.2 seconds or more. The upper limit is preferably 2 seconds or less, and more preferably 1 second or less. Thereby, conditions for plasticizing the cellulose material can be easily set, and thermal decomposition can be suppressed. The treatment time is preferably 0.1 second to 2 seconds, and more preferably 0.2 seconds to 1 second.

  The product of the ultrasonic output and the processing time is preferably 100 W · S or more, and more preferably 300 W · S or more. The upper limit is preferably 3000 W · S or less, and more preferably 900 W · S or less. Thereby, a cellulose material can be easily plasticized and thermal decomposition can be suppressed. The product of the ultrasonic output and the processing time is preferably 100 to 3000 W · S, and more preferably 300 W · S to 900 W · S.

  In the present invention, each material of the horn and the supporting metal jig may be a general material, and examples thereof include materials such as SUS and titanium.

  According to the present invention, the cellulosic material (wood pulp sheet or the like) can be changed into a film, sheet or the like by simple mechanical processing. The obtained plasticized cellulose is extremely useful as a packaging material, a supporting substrate such as a tape, a separation membrane, a dialysis membrane, a reverse osmosis membrane, and a battery separator.

  The crystal structure of the plasticized cellulose of the present invention is preferably type I. There are two types of cellulose crystal structures, type I and type II, and regenerated cellulose such as rayon changes from type I to type II due to chemical treatment in its production process, so it significantly reduces molecular weight and mechanical strength and other characteristics. Becomes a problem. The I-type crystal structure can be expected to improve various parameters related to mechanical strength, which is advantageous for various applications.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these.

Example 1
A dry sheet (moisture content 7 wt%, thickness 1.2 mm, basis weight 830 g / m ² ) of commercially available dissolving pulp (NDSP, manufactured by Nippon Paper Industries Co., Ltd.) was pressed at a pressure of 25 N / mm using a plastic welding machine made by Linco. ^2. Ultrasonic treatment was performed under the conditions of an ultrasonic frequency of 20 kHz, an ultrasonic treatment time of 0.5 seconds, and an output of 1500 W.

(Example 2)
Unbleached kraft pulp obtained from domestic hardwood mix, spruce, and Douglas fir is bleached with oxygen bleaching and C-E-H-D sequence (chlorine treatment-alkali treatment-hypochlorite treatment-chlorine dioxide treatment) As a result, a bleached pulp having an ISO whiteness of 85% was obtained.

This pulp was beaten with a Niagara beater to a Canadian standard freeness (CSF) of 230 ml, and then a rosin sizing agent (SPE manufactured by Arakawa Chemical Co., Ltd.) with 0.1% pulp and a sulfate band with 0 pulp. 0.06% was added, and a paper having a basis weight of 65 g / m ² was made with a long net paper machine. Further, a super calendar treatment was performed to obtain a semi-transparent paper having a thickness of 65 μm (water content: 6 wt%, basis weight 65 g / m ² ). This translucent paper was processed with a Herman ultrasonic welder (rotating horn type) under conditions of a press pressure of 10 N / mm ² , an ultrasonic frequency of 35 kHz, an ultrasonic processing time of about 0.5 seconds, and an output of 800 W. The total light transmittance measured by the method described later was 86%, and the haze was 54%.

(Comparative Example 1)
In Example 1, a sample was obtained in the same manner as in Example 1 except that the pressure applied to the dissolving pulp was 25 N / mm ² , the pressing time was 0.5 seconds, and no ultrasonic irradiation was performed.

  In Comparative Examples 2 and 3 below, an attempt to follow the effect of the laser treatment disclosed in Patent Document 3 and Non-Patent Document 5 was attempted.

(Comparative Example 2)
While pressing the dry sheet used in Example 1 with a mortar, using a pulse fiber laser (IPG-Yb fiber laser manufactured by Laserx), output 50%, frequency 30 kHz, processing speed 833 mm / sec, pitch: 1 line, path Processing was performed under several thousand conditions.

(Comparative Example 3)
In Comparative Example 2, the output was set to 100%, and the other conditions were processed under the same conditions.

(Evaluation test)
The following tests were performed on the samples obtained in Examples 1 and 2 and Comparative Examples 1 to 3. The results of Tests 1 and 2 are shown in Table 1, and the results of Test 3 are shown in FIG.

<Test 1: Visual observation>
The state of transparency, coloring and the like of the processing part was visually confirmed by comparison with the untreated part.

<Test 2: Transparency measurement>
Total light transmittance and haze were measured with a haze meter (manufactured by Murakami Color Research Laboratory).

<Test 3: Wide-angle X-ray diffraction measurement>
Using a wide-angle X-ray diffractometer (RINT2500 manufactured by Rigaku Corporation), measurement with transmitted light was performed with an X-ray source CuKα, output 50 kV, 300 mA, and a detector scintillation counter. FIG. 1 shows an X-ray profile of the sample of Example 1.

  The plasticized cellulose obtained in Example 1 was irradiated with light from the back and photographed from the front (FIG. 2). Moreover, each sample obtained in Comparative Examples 1 and 3 was also photographed (FIGS. 3 and 4).

As shown in Table 1, in Examples 1 and 2, the transparency of the film is increased by plasticization, and in Example 1 in which the sheet is thick, smoothing is also remarkable. The transparency of the plasticized cellulose of Example 1 is clear from the fact that the back light is transmitted (white portion at the center in FIG. 2).
On the other hand, in Comparative Example 1 in which the ultrasonic treatment was not performed and in Comparative Example 2 in which the laser treatment was performed at a lower output, the transparency of the film was not changed, and horn marks remained (dented portion in FIG. 3). In Comparative Example 3 in which laser treatment was performed at a higher output than Comparative Example 2, thermal decomposition occurred and a burnt mark remained on the back surface (darkening of the entire FIG. 4). These results indicate that the production method of the present invention can suppress thermal decomposition (burn) and obtain a transparent sheet. Moreover, in Comparative Examples 2 and 3, although it was difficult to reproduce the application of pressure and shear force described in the prior art, in the case of laser treatment, the behavior changes suddenly from no change to thermal decomposition. It was found difficult to find the plasticizing conditions located between them.

  The X-ray profile of FIG. 1 shows that the crystal structure of the plasticized cellulose of Example 1 is a typical type I. On the other hand, a transparent molding material made of regenerated cellulose such as rayon exhibits a type II crystal structure by chemical treatment in the production process. Therefore, the results of FIG. 1 show that the present invention provides a plasticized cellulose having a crystal structure of type I, which is clearly different in structure from a transparent molding material made of regenerated cellulose and is advantageous in various applications. I understand that.

Claims (6)

  A method for producing plasticized cellulose, comprising subjecting a cellulose material to ultrasonic treatment under press treatment. Pressing pressure in the press processing is ^{1N / mm 2 ~1000N / mm 2} , the manufacturing method according to claim 1.   The manufacturing method according to claim 1 or 2, wherein a frequency in the ultrasonic treatment is 10 kHz to 50 kHz.   The production method according to any one of claims 1 to 3, wherein an output of ultrasonic waves in the ultrasonic treatment is 500W to 3000W.   The manufacturing method according to any one of claims 1 to 4, wherein a treatment time of the ultrasonic treatment is 0.1 second to 2 seconds.   The plasticized cellulose obtained by the manufacturing method as described in any one of Claims 1-5.