Research | Forest resource material science, Kochi University （Hideaki Ichura Laboratory)

1. Disosal iaper waste recycling technology

With the aging of Japan's population, the amount of disposable adult diapers have been increasing. Currently, the majority of used disposable diapers are incinerated. However, the cost of auxiliary fuel and incineration residues are increasing due to the low flammability of disposable diapers.

In addition, incineration of disposable diapers tends to accelerate the deterioration of incinerators as a result of high-heat combustion, increasing repair costs and shortening the service life of incinerators. For this reason, the Ministry of the Environment has established guidelines to promote the recycling of disposable diapers.

In this study, we established a new paper diaper recycling technology that utilizes ozone. As a result, we were able to recover the pulp contained in used disposable diapers, which had been difficult in the past. This technology has made it possible to reuse pulp in disposable diapers. In addition, a demonstration test of this technology is underway in Shibushi City, Kagoshima Prefecture. Furthermore, full-scale implementation is scheduled to begin in FY2023, when a project related to the production of disposable diapers using the recovered pulp is scheduled to be launched.

Related paper
・Journal of cleaner production 276, 123350 (2020), DOI: https://doi.org/10.1016/j.jclepro.2020.123350.

2.　Development of biodegradable materials utilizing cellulose

This research is about biodegradable materials for paper prepared with cellulose of a wood component.

Then,the paper is required as a biodegradable materia,and is focused an alternative materilas of plastic. However, drawback of the paepr are wet paper strength (the paper strength wetted by water). In addition, the control of biodegradability is also important. For example, when paper is used as a mulch sheet for agriculture, if it decomposes before the crop is grown, the mulch sheet becomes meaningless.

Therefore, we are studing on the development of paper materials with both microbial control of degradation and wet paper strength using a simple method that utilizes phosphoric acid and urea.

Related paper
・ Cellulose, 26, 5105-5116 (2019) DOI: https://doi.org/10.1007/s10570-019-02423-y

3.　Development of functional paper using ionic liquids

We have attempted to prepare wet strength paper by partially dissolving the cellulose in paper using an ionic liquid (a new solvent that can dissolve cellulose). The wet strength reagents are used to maintain the strength of paper wetted by water. For examle, the these reagents are applied to water-resistant corrugated board, wrapping paper, paper towels, and tissue paper.

Polyamide-polyamine epichlorohydrin resin (PAE) is used as wet strength resing. However, because of the high toxicity of their byproduct, alternative reagent have recently become necessary from an environmental perspective.　

In this study, we used ionic liquids for the improvement of wet-strength paper. By ionic liquid treatment, the high wet stength was obtained and then, the paper with high wet sterength was composed entirely of cellulose.

The paper treated with ionic liquid can be used in aqueous environments. By adding activated carbon or catalyst to the paper, it is expected to be used as water purification paper or catalyst paper that can be used under aqueous environments.　

Paper made from pulp treated with ionic liquids has been shown to improve not only tensile strength, but also specific surface area, polyethylene glycol adsorption rate, and moisture retention rate.

Related paper
・Cellulose 27, 8317-8327 (2020), DOI: 10.1007/s10570-020-03303-6.
・Cellulose, 24(8), 3469-3477 (2017). DOI: 10.1007/s10570-017-1340-8.

4. Utilization of palm fiber (joint research with a university in Indonesia)

This study is an international collaboration on the effective utilization of waste generated by the palm oil industry in Indonesia.

Palm oil accounts for 12% of Indonesia's export industry. As a result, a large amount of waste from the palm oil industry is produced, and then, the palm fiber accounts for 22-24%. Palm fiber contains 50% cellulose, and the cellulose contained in the waste palm fiber is tried to be utilize as the cellulose products.

In this study, we prepared carboxyl methyl cellulose, and utilize in the food field. By utilizing ozone treatment, we were able to control the properties of carboxymethyl cellulose and add value to it.

Related paper
・Journal of applied polymer science 138, e54228 (2023), DOI: https://doi.org/10.1002/app.54228
・Journal of applied polymer science 138, e49610 (2021), DOI: https://doi.org/10.1002/app.49610

5.　Intelligent functional paper

Intelligent materials express functions in response to the external environment. We apply the cenceput of the intelligent material to paper and nonwovens. This will make it possible to create paper and nonwovens with detecting in the external environment and then, the paper and nonwoven sheet with novel function can be produced.

We prepared the paper that respond to components in body and the temperature change. The intelligent functional that releases odors in response to external changes was also prepared.

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・ Journal of Applied Polymer Science, 134(9) , 44530 (2017) DOI: https://doi.org/10.1002/app.44530.
・Chemical Engineering Journal, 245, 17-23(2014).　 DOI: https://doi.org/10.1016/j.cej.2014.02.019
・Journal of Applied Polymer Science, 129, 2139-2144 (2013). DOI: https://doi.org/10.1002/app.38941
・Journal of Applied Polymer Science, 127, 1725-1729 (2013). DOI: https://doi.org/10.1002/app.37902.
・ Journal of Materials Science, 45, 1343-1349 (2010) DOI: https://doi.org/10.1007/s10853-009-4088-1.
・Journal of Materials Science, 44, 992-997 (2009).DOI: https://doi.org/10.1007/s10853-008-3220-y
・Journal of Materials Science, 43, 1486-1491 (2008). DOI: https://doi.org/10.1007/s10853-007-2341-z
・ Journal of Materials Science, 40, 1987-1991 (2005).DOI: https://doi.org/10.1007/s10853-005-1221-7

6. Recycling of Paper Sludge

The pulp component of paper sludge discharged from the pulp and paper industry is incinerated, and the remaining inorganic materials are disposed of in landfills. The research about paper sludge was mainly studied about the reuse of inorganic materials because it is difficult to separate the pulp and the inorganic materilas from the paper sludge.

In this study, pulp and inorganic components are separated and recovered using ionic liquids. Ionic liquids have been reported to dissolve pulp components, and the use of ionic liquids can selectively dissolve only the pulp content, thereby enabling the separation and recovery of inorganic and pulp components.

Related paper
・ Journal of Material Cycles and Waste Management, SPECIAL FEATURE: ORIGINAL ARTICLE AGRO' 2014,18(2), 215-221, (2016). DOI :https://doi.org/10.1007/s10163-015-0391-x
・ Chemical Engineering Journal, 173, 129-134 (2011) DOI:https://doi.org/10.1016/j.cej.2011.07.048

7. Development of functional paper using interfacial polymerization reaction

In this research, we attempt to functionalize the surface of paper and nonwovens, which are sheet-like materials, with the keyword "control of nano-interface on paper surface".

The basic concept is to simultaneously prepare and fix the functional materials on the surface of paper using the nano-interface region formed on the paper surface. We try to create sheet-like materials with various functions.

We attempt to prepare polymer films directly on the surface of sheet materials such as paper and nonwoven fabrics using an interfacial polymerization reaction. The polymer films with microcapsule, fiber, and porous forms were prepared on the paper sufece.

Because it is possible to synthesize polymer films with various morphologies, it is expected that sheet-like materials will be developed according to the characteristics of their morphologies.

In this study, we studied about the basic experiments to elucidate the mechanism by which this morphology is changed. We were also investigaeted the insect repellent paper with a sustained release effect and adhesive paper that does not require release paper by utilizing this method.

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・Ichiura H., Kawahara U., “Polyamide film containing a molecularly imprinted polymer prepared on a paper surface by interfacial polymerization and its selective adsorption of benzalkonium chloride”, Journal of applied polymer science, e55077 (2023). DOI: https://doi.org/10.1002/app.55077.
・Chemosphere, 256, 127143 (2020). https://doi.org/10.1016/j.chemosphere.2020.127143
・ Industrial & Engineering Chemistry Research, 55(4), 961-966 (2016). DOI: https://doi.org/10.1021/acs.iecr.5b04548
・ Polymer bulletin, 72, 2621-2632 (2015). DOI: https://doi.org/10.1007/s00289-015-1426-0
・ Industrial & Engineering Chemistry Research, 52, 9137-9144 (2013). DOI: https://doi.org/10.1021/ie401082a
・Journal of Applied Polymer Science, 124, 242-247 (2012). DOI: https://doi.org/10.1002/app.33900
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1. Disosal iaper waste recycling technology

With the aging of Japan's population, the amount of disposable adult diapers have been increasing. Currently, the majority of used disposable diapers are incinerated. However, the cost of auxiliary fuel and incineration residues are increasing due to the low flammability of disposable diapers.

2. Development of biodegradable materials utilizing cellulose

This research is about biodegradable materials for paper prepared with cellulose of a wood component.

Therefore, we are studing on the development of paper materials with both microbial control of degradation and wet paper strength using a simple method that utilizes phosphoric acid and urea.

3. Development of functional paper using ionic liquids

Polyamide-polyamine epichlorohydrin resin (PAE) is used as wet strength resing. However, because of the high toxicity of their byproduct, alternative reagent have recently become necessary from an environmental perspective.

In this study, we used ionic liquids for the improvement of wet-strength paper. By ionic liquid treatment, the high wet stength was obtained and then, the paper with high wet sterength was composed entirely of cellulose.

The paper treated with ionic liquid can be used in aqueous environments. By adding activated carbon or catalyst to the paper, it is expected to be used as water purification paper or catalyst paper that can be used under aqueous environments.

Paper made from pulp treated with ionic liquids has been shown to improve not only tensile strength, but also specific surface area, polyethylene glycol adsorption rate, and moisture retention rate.

4. Utilization of palm fiber (joint research with a university in Indonesia)

This study is an international collaboration on the effective utilization of waste generated by the palm oil industry in Indonesia.

In this study, we prepared carboxyl methyl cellulose, and utilize in the food field. By utilizing ozone treatment, we were able to control the properties of carboxymethyl cellulose and add value to it.

5. Intelligent functional paper

We prepared the paper that respond to components in body and the temperature change. The intelligent functional that releases odors in response to external changes was also prepared.

6. Recycling of Paper Sludge

7. Development of functional paper using interfacial polymerization reaction

In this research, we attempt to functionalize the surface of paper and nonwovens, which are sheet-like materials, with the keyword "control of nano-interface on paper surface".

The basic concept is to simultaneously prepare and fix the functional materials on the surface of paper using the nano-interface region formed on the paper surface. We try to create sheet-like materials with various functions.

We attempt to prepare polymer films directly on the surface of sheet materials such as paper and nonwoven fabrics using an interfacial polymerization reaction. The polymer films with microcapsule, fiber, and porous forms were prepared on the paper sufece.

Because it is possible to synthesize polymer films with various morphologies, it is expected that sheet-like materials will be developed according to the characteristics of their morphologies.

In this study, we studied about the basic experiments to elucidate the mechanism by which this morphology is changed. We were also investigaeted the insect repellent paper with a sustained release effect and adhesive paper that does not require release paper by utilizing this method.

2.　Development of biodegradable materials utilizing cellulose

3.　Development of functional paper using ionic liquids

Polyamide-polyamine epichlorohydrin resin (PAE) is used as wet strength resing. However, because of the high toxicity of their byproduct, alternative reagent have recently become necessary from an environmental perspective.　

The paper treated with ionic liquid can be used in aqueous environments. By adding activated carbon or catalyst to the paper, it is expected to be used as water purification paper or catalyst paper that can be used under aqueous environments.　

5.　Intelligent functional paper