Method for front-back treatment of paper substrates with hydrophobic and biodegradable properties using pecvd and plasma etching

Abstract

A method for treating paper substrates to impart double-sided properties using plasma-enhanced chemical vapor deposition (PECVD) and plasma etching. The method involves receiving a paper substrate and performing a PECVD treatment on one side with a coating of hexamethyldisiloxane or ganoin under atmospheric pressure. The opposite side undergoes an oxygen plasma etching treatment. This dual treatment results in the paper substrate having a hydrophobic coating on one side and enhanced biodegradability on the other. The resulting biomaterial offers an environmentally sustainable packaging solution by combining moisture resistance and degradability within a single substrate. Classes: B65D and C08J

Description

[0001] Method for Front-Back Treatment of Paper Substrates with Hydrophobic and Biodegradable Properties Using PECVD and Plasma Etching

[0002] Field of the Invention

[0003] The present disclosure relates to materials science and engineering, in particular methods for surface treatment of paper substrates to impart hydrophobic and biodegradable characteristics using plasma- enhanced chemical vapour deposition ( PECVD) and Plasma Etching techniques .

[0004] Summary

[0005] According to one aspect of the present invention, a method for treating paper to create a coupled biomaterial comprises receiving a paper substrate ; performing a plasma-enhanced chemical vapour deposition ( PECVD) treatment on Side A of the paper substrate using atmospheric pressure and a hexamethyldisiloxane coating; performing an oxygen plasma etching treatment on Side B of the paper substrate ; wherein the PECVD treatment on Side A creates a hydrophobic hexamethyldisiloxane coating, and the oxygen plasma etching treatment on Side B improves the biodegradability of the paper substrate ; and obtaining a treated paper biomaterial with hydrophobic properties on Side A and enhanced biodegradability on Side B .

[0006] According to another aspect , a method for treating paper to create a biomaterial comprises receiving a microincision treatment ; performing a plasma- enhanced chemical vapour deposition ( PECVD) treatment on Side A of the paper substrate using atmospheric pressure and a Ganoin coating; performing an oxygen plasma etching treatment on Side B of the paper substrate ; wherein the PECVD treatment on Side A creates a hydrophobic Ganoin coating, and the oxygen plasma etching treatment on Side B improves the biodegradability of the paper substrate ; and obtaining a treated paper biomaterial with hydrophobic properties on Side A and enhanced biodegradability on Side B .

[0007] Background

[0008] Materials used in the packaging industry often balance the need for liquid permeation resistance with environmental considerations . Traditional substrates derived from natural sources are degradable but do not provide suf ficient protection against moisture . Conversely, substrates designed for moisture impermeability often do not degrade easily, posing ecological challenges . The industry is seeking a solution that harmonises these opposing attributes , aiming for a substrate that resists moisture whilst being aligned with environmental sustainability .

[0009] Existing methods for improving substrate properties include various surface treatment techniques . However, these approaches have not satis fied the need for a substrate that simultaneously exhibits water-repellent and degradability characteristics . There is an urgent demand for an adaptable and environmentally friendly packaging substrate capable of maintaining integrity after liquid exposure without relying on additional agricultural resources whilst continuing to degrade after use. This context highlights the need for a new substrate enhancement method capable of integrating these dual characteristics within a single material.

[0010] The increase and decrease in wettability can be explained by the Wenzel surface.

[0011] The increase in wettability on a Wenzel surface occurs when a liquid deposits on a rough solid surface in such a way as to penetrate the surface roughness, increasing the contact area between the liquid and solid surface. This phenomenon leads to a decrease in the contact angle, i.e., the angle formed between the liquid and solid surface.

[0012] To better understand this concept, it is important to consider Wenzel's equation, which describes the relationship between the measured contact angle (0m) on a rough surface, Young's angle (0Y) of the liquid on a smooth surface and the roughness factor (r) of the surface: cos0m = cos0Y * r

[0013] Where :

[0014] • 0m is the contact angle measured on the rough surface

[0015] • 0Y is Young's angle of the liquid on a smooth surface

[0016] • r is the surface roughness factor

[0017] The roughness factor (r) is a dimensionless value representing the surface roughness. It can be calculated in several ways, but in general it is defined as the ratio between the effective surface and the projected surface.

[0018] If the surface is hydrophilic (0Y < 90°) , Wenzel's equation tells us that the measured contact angle (0m) will be less than Young's angle (0Y) on a smooth surface. This means that the liquid will spread more on a rough surface than on a smooth surface, increasing its wettability.

[0019] Conversely, if the surface is hydrophobic (0Y > 90°) , the measured contact angle (0m) will be greater than Young's angle (0Y) on a smooth surface. In this case, the liquid will cluster into a droplet on the rough surface, decreasing wettability.

[0020] The increase in wettability on a Wenzel surface is due to several factors:

[0021] • Increased surface area: Surface roughness increases the effective area with which the liquid can come into contact, decreasing the contact angle.

[0022] • Capillary forces: Surface asperities create small cavities that trap the liquid, favouring its adhesion to the surface.

[0023] • Chemical interactions: Chemical interactions between the liquid and the surface can influence wettability, especially on hydrophilic surfaces.

[0024] The decrease in wettability on Wenzel surfaces has several important applications, including:

[0025] • Non-stick coatings: Low wettability surfaces can be used to create non-stick coatings, which prevent liquids from adhering to the surface. • Surface cleaning : Surfaces with low wettability can be easier to clean, as the liquid is able to penetrate better into the surface asperities and remove dirt .

[0026] • Biomaterials : Surfaces with low wettability can be used in biomaterials , such as implants and prostheses , to improve integration with biological tissues .

[0027] It is important to emphasise that the variation in wettability on a Wenzel surface depends on several factors , including the nature of the liquid, surface chemistry and surface topography . Understanding these factors is essential for designing and creating surfaces with desired wettability properties .

[0028] Description

[0029] The field of materials science continuously seeks to develop substrates that balance functional performance with environmental sustainability . In the packaging sector, this balance is particularly challenging . Traditional paper substrates , although biodegradable , fail to provide adequate resistance to liquid permeation . This limitation represents a signi ficant problem for packaging applications where moisture resistance is fundamental for maintaining content integrity . Conversely, substrates that offer ef fective barriers against moisture often do so at the expense of biodegradability, leading to environmental problems after use . The industry therefore faces the challenge of creating a substrate that is both moisture-resistant and environmentally degradable in the long term . Current solutions in the industry involve various surface treatments to improve the properties of paper substrates . However, these treatments typically focus on improving either the moisture resistance or the biodegradability of the substrate , but not both . For example , coatings that impart hydrophobic properties to paper can hinder the paper ' s ability to degrade naturally, whilst treatments that improve biodegradability can compromise the substrate ' s moisture resistance . This dichotomy presents a signi ficant disadvantage , as there is an urgent need for a substrate that can withstand liquid exposure during use yet degrade easily in a post-use environment . Existing methods have not adequately addressed this need, leaving a gap in the market for a dual- function substrate capable of meeting both moisture resistance and environmental sustainability requirements .

[0030] The present disclosure provides a method for treating paper substrates to impart dual-sided properties using plasma-enhanced chemical vapour deposition ( PECVD) and plasma etching . The method involves receiving a paper substrate and performing a PECVD treatment on one side with a hexamethyldisiloxane or ganoin coating under atmospheric pressure . The opposite side undergoes an oxygen plasma etching treatment . This dual treatment causes the paper substrate to have a hydrophobic coating on one side and enhanced biodegradability on the other . The resulting biomaterial of fers a solution for environmentally sustainable packaging by combining moisture resistance and degradability within a single substrate . The described method therefore addresses the mentioned problems by providing a substrate that is both hydrophobic and biodegradable , satis fying the industry ' s need for a versatile and environmentally friendly packaging material .

[0031] Technical Ef fect

[0032] The technical ef fect of claim 1 is that the method provides a solution for creating a paper biomaterial with hydrophobic and biodegradable properties . By performing a PECVD ( Plasma Enhanced Chemical Vapour Deposition) treatment on Side A of the paper substrate using atmospheric pressure and a hexamethyldisiloxane coating, a hydrophobic coating is created . This coating makes the paper substrate resistant to liquid permeation, ensuring moisture resistance . Furthermore , by performing an oxygen plasma etching treatment on Side B of the paper substrate , the biodegradability of the substrate is improved . This dual-sided treatment enables the paper biomaterial to display both hydrophobic and biodegradable properties , satis fying the need for a versatile and environmentally friendly packaging material .

[0033] The technical ef fect of claim 10 is that the method provides a solution for creating a paper biomaterial with hydrophobic and biodegradable properties . By performing a PECVD ( Plasma Enhanced Chemical Vapour Deposition) treatment on Side A of the paper substrate using atmospheric pressure and a ganoin coating, a hydrophobic coating is created . This coating makes the paper substrate resistant to liquid permeation, ensuring moisture resistance . Furthermore , by performing an oxygen plasma etching treatment on Side B of the paper substrate , the biodegradability of the substrate is improved . This dual-sided treatment enables the paper biomaterial to display both hydrophobic and biodegradable properties , satis fying the need for a versatile and environmentally friendly packaging material .

[0034] The invention is described according to two methods :

[0035] Method 1

[0036] The design consists of two treatments : the first is a PECVD treatment on Side A using a hexamethyldisiloxane coating and the second is an oxygen plasma etching on Side B .

[0037] The invention involves a paper film, 50 microns thick, to which a plasma treatment is applied via PECVD ( Plasma Enhanced Chemical Vapour Deposition) on Side A and via a plasma etching treatment on Side B .

[0038] Side A: On the hydrophobic side , a layer of approximately 1 . 5 microns composed of hexamethyldisiloxane was used as coating material . The process was carried out with a mixture of gas and oxygen and similar silicon which led to deposition in a short time .

[0039] Side B : Side B was created with plasma etching, derived from a treatment with only oxygen for a time unit of 30 seconds . In this process , the creation of microincisions tens of nanometres deep was noted .

[0040] Method 2

[0041] The techniques are the same as the PECVD treatment of Side A and the plasma etching of Side B . It di f fers in that the coating ( instead of being hexamethyldisiloxane) will be made with ganoin, a material derived from fishing waste, chemically treated, put in solution and inserted into the plasma chamber via aerosol.

[0042] Description of Methods and Their Preparation

[0043] Side A Treatment

[0044] Method 1 -- Hexamethyldisiloxane-based

[0045] Side A is created with PECVD treatment with hexamethyldisiloxane coating.

[0046] Image of hexamethyldisiloxane molecule

[0047] Side A treatment path:

[0048] 1. Sample introduction.

[0049] 2. Air aspiration via rotary pump.

[0050] 3. Introduction of precursor gas: oxygen is introduced up to atmospheric pressure (02) .

[0051] 4. Plasma activation: within the chamber, a plasma is generated using radiofrequencies (RF) of 13.56 Hz. The plasma provides the energy necessary to activate the precursor gases and trigger chemical reactions.

[0052] 5. Film deposition: The activated hexamethyldisiloxane is inserted into the active plasma, leading to the formation of molecules and radicals . These combine and deposit on the substrate surface , forming a thin film with the desired structure and properties .

[0053] 6 . Product extraction : Once deposition is completed, the substrate is extracted from the vacuum chamber . The deposited film is ready to be used or subj ected to further processing .

[0054] Method 2 -- Ganoin-based

[0055] Method 2 is performed with a coating on Side A in ganoin derived from the solution of fish waste placed in solution with IM acetic acid .

[0056] Detailed ganoin solubilisation procedure :

[0057] 1 . Preparation occurs with mechanical fragmentation of the material

[0058] 2 . The fragments are placed in solution with acetic acid at a concentration of 1 M buf fered at pH 2 . 37 .

[0059] 3 . " The solution is heated to 60 degrees Celsius under a fume hood until the solution completely solubilises . "

[0060] Ganoin molecule

[0061] Side B Treatment - Plasma Etching 1. System preparation

[0062] • Gas removal rotary pump.

[0063] • Gas introduction: The process gas, such as oxygen, is introduced into the chamber up to atmospheric pressure through appropriate gas supply systems.

[0064] 2. Plasma generation

[0065] • Electric field application: An electric field at 13.56 Hz (RE) is applied to the reaction chamber through electrodes, ionising the gas molecules present (e.g., oxygen) and creating the plasma.

[0066] • Plasma formation: The plasma thus generated consists of ions, electrons, free radicals and neutral molecules and is used to etch the substrate material.

[0067] 3. Substrate etching

[0068] • Ion bombardment: The ions present in the plasma bombard the substrate surface, causing material etching through a process of physical erosion (sputtering) and chemical reactions.

[0069] • Chemical reactions: Free radicals and ions react chemically with the substrate material, forming volatile compounds that are removed from the surface.

[0070] 4. Process control

[0071] • Parameter regulation: Throughout the process, parameters such as RE power, gas flow and temperature are monitored and adjusted to control the speed and precision of etching. 5 . End of etching process

[0072] • Plasma shutdown : Once the desired etching is completed, the electric field is turned of f to terminate plasma generation .

[0073] • Gas and residue discharge : Residual gas and etching by-products are discharged from the reaction chamber .

[0074] 6 . Substrate recovery

[0075] • Substrate release : The etched substrate is removed from the reaction chamber for further processing or analysis .

[0076] Terms

[0077] PECVD is the acronym for Plasma Enhanced Chemical Vapour Deposition . It is a process used in semiconductor manufacturing and thin film deposition . In PECVD, plasma is generated by applying a high- frequency electric field to a mixture of gas or vapour within a vacuum chamber . This plasma contains highly reactive chemical species that can enhance the deposition of thin films on a substrate . In the context of the patent application, PECVD is used to perform a surface treatment on paper substrates to create a hydrophobic coating on one side , contributing to moisture resistance .

[0078] Plasma Etching is a surface treatment technique used to sculpt surfaces at the microscopic level with high precision . It is a fundamental process in microelectronics , particularly for creating integrated circuits ( ICs ) found in computers and other devices . Plasma etching involves generating a plasma, consisting of ions, electrons, free radicals and neutral molecules, by applying a high-frequency electric field to a gas (such as oxygen) within a reaction chamber. The ions present in the plasma bombard the substrate surface, causing physical erosion (sputtering) and chemical reactions that result in material removal. This technique enables precise material removal and the creation of intricate patterns or structures on the substrate surface. In the context of the patent application, plasma etching is used to improve the biodegradability of the paper substrate, creating microincisions that favour its degradation.

[0079] Description of Figures

[0080] Fig. 1: The figure illustrates a perpendicular section to the sheet (b) where the composition of the following film is seen in detail. It is created with a double treatment: one hydrophobic derived from a PECVD process and another hydrophilic (c) derived from an Etching process. At Side A, a coating of silicon-like material can be seen, whilst at Side B there are microincisions that allow greater absorption of liquid material. Indications: (a) : coating layer; (b) : paper layer; (c) : etching layer.

[0081] Fig. 2: Illustrates the contact angle of the material without any treatment and measures a contact angle of 107 degrees. In this figure, the material surface free from any treatment can be noted.

[0082] Fig. 3: Illustrates the contact angle of the hydrophilic angle (c) using the droplet technique which complies with the UNI EN 828:2013 standard. Its contact angle is 56.3 degrees. In this image, a reduction in contact angle derived from Plasma Etching can be noted.

[0083] Fig. 4: Illustrates the contact angle of the hydrophobic side (Side A) using the contact angle measurement technique via droplet which complies with the UNI EN 828:2013 standard. The measured contact angle is 124 degrees. In this image (Side A surface) , a reduction in surface angle derived from PECVD can be noted.

Claims

Method for Front-Back Treatment of Paper Substrates with Hydrophobic and Biodegradable Properties Using PECVD and Plasma EtchingClaims1 . A method for treating paper to create a biomaterial with hydrophobic and biodegradable properties , comprising the steps of :- receiving a paper substrate ; performing a Plasma Enhanced Chemical Vapour Deposition ( PECVD) treatment on Side A of the paper substrate using pressure < 1 atm and a hexamethyldisiloxane coating;- performing an oxygen plasma etching treatment on Side B of the paper substrate ;- wherein the PECVD treatment on Side A creates a hydrophobic coating of hexamethyldisiloxane , and the oxygen plasma etching treatment on Side B improves the biodegradability of the paper substrate ; and obtain a treated paper biomaterial with hydrophobic properties on the Side A and enhanced biodegradability on the Side B .2 . The method according to claim 1 wherein the PECVD on the A-side of the paper substrate uses pressure < 1 atm and a ganoin coating instead of the hexamethyldisiloxane coating, incorporating all other features of claim 1 . In this way the PECVD treatment on the Side A creates a hydrophobic ganoin coating, and the oxygen plasma etching treatment on the Side B improves the biodegradability of the papersubstrate . The ganoin is subj ected to appropriate solubili zation with IM acetic acid before its use .3 . The method according to claims 1 and 2 , wherein the paper substrate is pretreated with a surface activation process prior to the PECVD treatment on the Side A.4 . The method according to claim 3 , wherein the surface activation process comprises plasma treatment using a mixture of gases and hexamethyldisiloxane or ganoin precursors .5 . The method according to claims 1 and 2 , wherein the hexamethyldisiloxane or ganoine coating on Side A is applied using a PECVD coating technique .6 . The method according to claims 1 and 2 , wherein the paper substrate is selected from the group consisting of glossy paper, coated paper, cast- coated paper and mixes of the same papers .7 . The method according to claim 6 , wherein the paper substrate is further treated with a primer layer prior to the PECVD treatment on Side A.8 . The method according to claims 1 and 2 , wherein the PECVD treatment on Side A is carried out using a mixture of hexamethyldisiloxane or ganoine and other precursor gases .9 . The method according to claims 1 and 2 , wherein the paper substrate is subj ected to a surface cleaning process prior to the PECVD treatment on Side A to remove contaminants .10 . The method of claim 9 , wherein the surface cleaning process comprises a combination of mechanical cleaning and solvent cleaning steps .

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