WO2021126128A1

WO2021126128A1 - A self-healing filament embodiment

Info

Publication number: WO2021126128A1
Application number: PCT/TR2020/051304
Authority: WO
Inventors: Gökçenur SAĞLAM
Original assignee: Ermetal Otomoti̇v Ve Eşya Sanayi̇ Ti̇caret Anoni̇m Şi̇rketi̇
Priority date: 2019-12-18
Filing date: 2020-12-15
Publication date: 2021-06-24

Abstract

The invention relates to a self-healing filament embodiment which is made of polylactic acid polymer in which microcapsules comprising linseed oil in their core structure and comprising chitosan in their shell structure are integrated.

Description

A SELF-HEALING FILAMENT EMBODIMENT

Field of the Invention

The invention relates to a self-healing filament embodiment and production method used in layered manufacturing applications such as the automotive, defense and aviation sector.

The invention particularly relates to a filament that comprises polylactic acid polymer in which microcapsules integrated in, wherein the microcapsules comprise linseed oil in their core structure and comprise chitosan in their shell structure.

State of the Art

The applications of the layered production process in fields such as automotive, defense and aviation are increasing day by day. In the state of the art, it is mostly used in the production of complex parts. However, the strength between the layers is very weak in the zet direction in the products manufactured by the layered production process, thus there is damage between the layers, adhesion problem is seen, or the material is damaged by external factors. In such a case, damaged parts are usually replaced or repaired by various methods such as screws and fasteners etc. This causes cost and time loss.

In order to repair these damages, developing self-healing materials becomes an important issue recently. There are many studies on self-healing microcapsules. However, there are not many studies on the integration of these microcapsules on the filaments. Among current studies, there are studies on different materials with mostly different processes.

The following applications are encountered in the literature regarding the subject matter:

The Turkish patent application numbered TR 2016/17649 relates to a wound cover made of chitosan and polylactic acid (PLA) nanofibers prepared by electro-spinning method. The solution of the mixture with trifluoroacetic acid is prepared in said production method. This invention differs by its production method, the auxiliary materials used, and the product obtained. PCT application numbered WO2015143167A1 relates to self-healing cables and cable sheaths. Self-healing cables reduce voltage fluctuations caused by current flowing through the insulating layer system in high-voltage applications. The self-healing cables of mentioned invention comprise at least one conductor, at least one sheath surrounding said conductor and at least one dielectric sheath surrounding said sheath. The cable compared to traditional cable products, comprises a carbon-based conductor made of graphene or graphite for improved flexibility and elongation features, reduced weight and extended service life. Although aim of said invention is similar, the composition of the raw material used is different.

As a result, due to the above mentioned disadvantages and the insufficiency of the current solutions regarding the subject matter, a development is required to be made in the relevant technical field.

Brief Description of the Invention

The present invention is related to a self-healing filament embodiment which fulfills the above mentioned requirements, eliminates all disadvantages and brings some additional advantages.

The main aim of the invention is to obtain advantages in terms of cost and time by enabling the property of self-repair without replacement of the damaged parts in the composite and layered production process.

An aim of the invention is to protect human health and the environment by combining the microcapsule formed by the vegetable raw materials in the composition with a biocompatible polymer such as PLA.

Another aim of the invention is to provide a self-healing microcapsule which can be used in pharmaceutical, cosmetic, medicine, agriculture, paper, textile and food sectors as well as the automotive, defense and aviation sectors.

In order to fulfill the above mentioned aims, the present invention is a self-healing filament embodiment which is made of polylactic acid wherein microcapsules having linseed oil in its core structure and comprising chitosan in its shell structure are integrated therein and a production method thereof. The structural and characteristic features of the present invention will be understood clearly by the following detailed description and therefore the evaluation shall be made by taking the detailed description into consideration.

Detailed Description of the Invention

In this detailed description, the inventive self-healing filament embodiments described only for clarifying the subject matter in a manner such that no limiting effect is created.

The invention particularly relates to a self-healing filament which is made of polylactic acid polymer in which microcapsules comprising linseed oil in their core structure and comprising chitosan in their shell structure are integrated.

Furthermore, said microcapsules preferably comprise hydrochloric acid, acetic acid, polyvinyl alcohol and/or polysorbate 80, ethyl alcohol and/or methyl alcohol.

The invented filament preferably comprises linseed oil, chitosan, polylactic acid, hydrochloric acid, acetic acid, poly vinyl alcohol and ethyl alcohol.

The invented filament preferably comprises 0.5-2% linseed oil, 0.5-5% chitosan, 30-50% polylactic acid, 0-1.5% hydrochloric acid, 0.05-% 1 ,5 acetic acid, 4-6% poly vinyl alcohol, 40-80% ethyl alcohol on average by weight.

According to a preferred embodiment of the invention, the filament comprises 1% linseed oil, 2.5% chitosan, 40% polylactic acid, 0.5% hydrochloric acid, 1% acetic acid, 5% poly vinyl alcohol, 50% ethyl alcohol on average by weight.

The invented filament production method comprises the following process steps: i. dissolving of the chitosan in acetic acid, ii. making the dissolved chitosan surface functional, iii. fixing the functionalized chitosan with a stabilizer, iv. mixing the solution with pure water to make it homogeneous, v. adding hydrochloric acid to adjust the solution pH, vi. obtaining micro capsules by adding linseed oil to chitosan solution, vii. drying and collecting the microcapsule with a filter, viii. obtaining filament by adding the collected microcapsules into the polylactic acid polymer in the extruder.

According to a preferred embodiment of the invention, it is mixed in 1% acetic acid at 800 rpm for 20 minutes so as to functionalize the chitosan surface (ii).

According to a preferred embodiment of the invention, the functional surface is protected by an average of 5% by weight of poly vinyl alcohol stabilizer (iii).

According to a preferred embodiment of the invention, the solution is made homogeneous by mixing the same with 200 ml of distilled water at room temperature (iv).

According to a preferred embodiment of the invention, the pH of the solution is adjusted until it becomes 3 with hydrochloric acid so as to provide microcapsule strength (v).

According to a preferred embodiment of the invention, the microcapsule is obtained by adding 1.50 % ml of linseed oil into chitosan solution and waiting for 4 hours at 55 ° C (vi).

According to a preferred embodiment of the invention, micro capsules are collected by mixing at 600, 800 and 900 rpm respectively (vii).

According to a preferred embodiment of the invention, a twin-screw extruder is used to obtain filament (viii).

The inventive production method is explained in detail herein below. It dissolves in 1% acetic acid solution by weight so as to functionalize the chitosan surface. The functional surface is protected by stabilizer (PVA). The solution is mixed with pure water so as to make it homogeneous. The pH of the solution is adjusted approximately to 3 with hydrochloric acid so as to provide microcapsule strength. A linseed oil in an amount of 1% by weight is added into the chitosan solution and kept for a few hours so as to obtain microcapsules. Formed microcapsules are collected after they are dried. Self-healing filament is obtained by drawing the obtained microcapsules with PLA polymer through the extruder by adjusting the temperature, extruder speed and drawing speed.

The melting temperature in the PLA extruder varies between 150-210 ° C. The filament diameter to be obtained varies between 1.00-2.00 mm. It is confirmed by tests such as FT-IR, SEM, TGA, DSC etc. that microcapsules contain regenerative agent. Then, the twin-screw extruder is adjusted to the appropriate parameters for filament drawing and it is again supported by the SEM image wherein the microcapsules are homogeneously dispersed in the filament.

It is mixed in 1% acetic acid at 800 rpm for 20 minutes so as to functionalize the chitosan surface. The functional surface is protected by 5% stabilizer (PVA). The obtained solution is mixed with 200 ml distilled water so as to make it homogeneous at room temperature. The pH of the solution is adjusted until it becomes 3 with hydrochloric acid for microcapsule strength. The microcapsule is obtained by adding 1 ,50 % ml of linseed oil into chitosan solution and waiting for 4 hours at 55 ° C. The formed microcapsules are collected by mixing at 600, 800 and 900 rpm speeds and then microcapsule particles are obtained after they are dried. Self-healing filament is obtained by drawing the obtained microcapsules with PLA polymer through the extruder by adjusting the determined temperature, extruder speed and drawing speed.

Chitosan comprising self-renewable natural polymers. Moreover, it is a low cost, non toxic, antibacterial, biodegradable polymer that can be found in nature plentifully.

Linseed oil is the most used oil in the coating industry. It has anti-corrosion and repair properties. It is produced from renewable resources and is advantageous in terms of cost.

Polylactic acid (PLA) is a biodegradable thermoplastic polymer produced from starch-rich plant resources such as corn, sugar cane and wheat. Since it is a bioabsorbable polymer, it has only been limited to biomedical field during a long period of time. However, today its applications have also increased in garment, fork, knife, and kitchenware such as plates, trays, glasses and food packaging materials with the development of layered manufacturing method.

According to the current methods, studies concerning to gain self-healing property will provide advantages in terms of cost and time without replacement of the damaged parts. The self-healing filament is produced by integrating the microcapsule structure that contains a regenerative agent into the filament. The microcapsule structure comprising the core and the matrix structure that is inside the core and can be able to provide the regenerative agent property. In the inventive study, it will be applicable not only in products with low cost to be used only in the automotive and aviation industry, but also it will be applicable in the food sector by using herbal products in both of the structures.

Chitosan, which can be found in nature plentifully, will be used as the core structure and linseed oil will be used as a regenerative agent.

Since chitosan is both economical and nontoxic and biocompatible, it is commonly used in various industrial (pharmaceutical, cosmetic, medicine, agriculture, paper, textile and food) fields with its layered production method.

The linseed oil has an anti-corrosion structure in addition to its environmental and self- healing properties. In the inventive composition, the microcapsule, which is formed by the herbal raw materials, will be combined with a biocompatible polymer such as PLA so as to prevent negative consequences that may affect human health.

Claims

1. A self-healing filament embodiment which is made of polylactic acid polymer in which microcapsules comprising linseed oil in their core structure and comprising chitosan in their shell structure are integrated.

2. The filament embodiment according to claim 1 , characterized in that; the microcapsules further comprise hydrochloric acid, acetic acid, polyvinyl alcohol and/or polysorbate 80, ethyl alcohol and/or methyl alcohol.

3. The filament embodiment according to claim 2, characterized in that; the filament comprises linseed oil, chitosan, polylactic acid, hydrochloric acid, acetic acid, poly vinyl alcohol and ethyl alcohol.

4. The filament embodiment according to claim 3, characterized in that; the filament comprises 0.5-2% linseed oil ,0.5-5% chitosan, 30-50% polylactic acid, 0-1.5% hydrochloric acid, 0.05-% 1 ,5 acetic acid, 4-6% poly vinyl alcohol, 40-80% ethyl alcohol on average by weight.

5. The filament embodiment according to claim 4, characterized in that; the filament comprises 1% linseed oil, 2.5% chitosan, 40% polylactic acid, 0.5% hydrochloric acid, 1% acetic acid, 5% poly vinyl alcohol, 50% ethyl alcohol on average by weight.

6. A self-healing filament production method according to claim 1 , characterized in that, the method comprises following process steps: i. dissolving of the chitosan in acetic acid, ii. making the dissolved chitosan surface functional, iii. fixing the functionalized chitosan with a stabilizer, iv. mixing the solution with pure water to make it homogeneous, v. adding hydrochloric acid to adjust the solution pH, vi. obtaining micro capsules by adding linseed oil to chitosan solution, vii. drying and collecting the microcapsule with a filter, viii. obtaining filament by adding the collected microcapsules into the polylactic acid polymer in the extruder.

7. The filament production method according to claim 6, characterized in that; comprising mixing in 1% acetic acid at 800 rpm for 20 minutes so as to functionalize the chitosan surface (ii).

8. The filament production method according to claim 6, characterized in that; the functional surface is protected by an average of 5% by weight of poly vinyl alcohol stabilizer (iii).

9. The filament production method according to claim 6, characterized in that; the solution is made homogeneous by mixing the same with 200 ml of distilled water at room temperature (iv).

10. The filament production method according to claim 6, characterized in that; the pH of the solution is adjusted until it becomes 3 with hydrochloric acid so as to provide microcapsule strength (v).

11. The filament production method according to claim 6, characterized in that; the microcapsule is obtained by adding 1 .50 % ml of linseed oil into chitosan solution and waiting for 4 hours at 55 ° C (vi).

12. The filament production method according to claim 6, characterized in that; micro capsules are collected by mixing at 600, 800 and 900 rpm respectively (vii).

13. The filament production method according to claim 6, characterized in that; twin- screw extruder is used so as to obtain filament (viii).

14. The filament production method according to claim 1 , characterized in that; the diameter of the filament is in the range 1.00-2.00 mm.