Obtaining Waterproof Coating Material

Development of Waterproof Coating Material and High-Performance Shoe Adhesive

Abstract

Waterproof materials are mostly chemical in nature and provide temporary solutions. They are also costly and create permanent deformation problems on shoe surfaces. Adhesives represent one of the most critical areas for the shoe industry. Adhesives are interface materials that bond objects together. These adhesives, which consist of chemicals, are critical to shoe longevity. In daily use, footwear undergoes constant motion and deformation. In cases of heavy contact with shoes, greater deformations occur and the upper/side parts separate from the sole. Many organizations are searching for ideal adhesive solutions to address such problems. For this purpose, a coating material has been developed in this study that provides both high-performance adhesive and waterproofing properties for shoe products.  

1. Introduction

Adhesives are natural and synthetic substances that bind objects and surfaces together. Many adhesives are produced for specific purposes depending on the industry and the substrates to be bonded. Adhesives are mostly composed of polymers or resins, which are chemical structures that can be classified as plastics. Each adhesive has its own formula. The adhesive selection varies according to the material requirements. Adhesives can be divided into three main categories: natural adhesives, semisynthetic adhesives and synthetic polymers [1,2].   Natural Adhesives: In ancient times, natural adhesives were obtained from plants and animal parts such as bones, skin and glands. Animal adhesives were mostly preferred for rough work and areas requiring strong bonding, while plant-based adhesives were used for fine work such as paper gluing (starch, etc.). During the Middle Ages, animal-based natural adhesives were made from fats and tissues derived from cattle such as cows, bulls and buffaloes, as well as nerve tissue and tendons. Recent studies have produced stronger natural adhesives. Plant-Based Adhesives: These are mostly created by processing starchy plants. Apart from starch, resins from certain tree species also serve as plant-based adhesives. Starch is a polymeric material with high molecular weight found abundantly in wheat and potatoes. Starch is a polymer of glucose applied when cold and is odourless. However, starch is not a strong adhesive and has low water resistance. It is processed to increase its resistance. Dextrin, a gummy substance obtained from starch degradation through heating, shows greater moisture resistance than starch. Therefore, dextrin is preferred over starch. There are three types of dextrin: white dextrin, yellow dextrin and canary dextrin, and English gum. When barox is added to dextrin, its tackiness and strength increase. In the Ottoman period, an adhesive called çiriş was used in leather and leather shoe manufacturing instead of adhesives such as derby and bally used today. This adhesive is obtained from dextrin found in the roots of çiriş, a lily family plant with white flowers. Protein-Based Adhesives: Among protein-based adhesives produced from animal parts such as bones, skin and gills, the most widely used in the protective field is what is known today as animal glue. Animal glue is a gelatinous adhesive made from animal bones and skin, appearing in dark purple and brown colours, and used after dissolving in water. [caption id="attachment_143952" align="aligncenter"] Figure 1. Water sealant and shoe adhesive[/caption] Adhesives Used in Shoe Manufacturing: • Hotmelt Adhesive, • Solvent-Based Polychloroprene Adhesive (Derby), • Solvent-Based Elastomer-Based Adhesive, • Solvent-Based Polyurethane Adhesive, • One-component, polychloroprene-based, water-based adhesive [1,2].   In addition to adhesives, waterproofing products represent one of the most important requirements. These chemical-based materials, when sprayed on the shoe surface, provide protection for several hours and exhibit hydrophobic properties that repel incoming liquid. However, there are known limitations. Products made with water repellent technology are water-resistant but do not provide the same level of shoe protection as true waterproof features. Some waterproof shoes do not allow air circulation. There are models designed for outdoor sports use. They keep feet warm in winter and prevent moisture sensation. Through shoe technologies, products with different features are manufactured. The intended seasons and weather conditions for shoe use influence technology selection. Among well-known shoe technologies is waterproofing, also called waterproof protection. Waterproof shoes are mostly used in winter and spring. In winter and autumn, demand for waterproof boots is high. In spring, shoes are preferred over boots [3]. Water sealant and shoe adhesive are shown in Figure 1. [caption id="attachment_143953" align="aligncenter"] Figure 2.1. Waterproofing coating material and trial testing[/caption] In this study, a coating material providing high-performance adhesive and waterproofing properties for shoe products has been developed.

2. Materials and Method

2.1. Material

Citric acid-coated calcite, silica, aerogel and proprietary matrix material for waterproofing, along with high-performance instant adhesive of proprietary composition, were selected.

2.2. Method

A mixture was prepared using citric acid-coated calcite at 3-7.5%, silica at 1-5%, aerogel at 1-5% and proprietary matrix material, and was sprayed at a specific flow rate onto summer and winter shoes using a spray gun. After waiting for 30 minutes, water-tightness performance was measured by passing through a water-intensive test road [4]. The waterproofing coating material and trial studies are shown in Figure 2.1.   The proprietary high-performance fast-setting adhesive was injected into the separated sole area of the shoe. It was allowed to bond rapidly with the upper material, with complete hardening achieved in 15 minutes [5]. The high-performance shoe adhesive application with proprietary formulation is shown in Figure 2.2. [caption id="attachment_143954" align="aligncenter"] Figure 2.2. High-performance shoe adhesive application with proprietary formulation[/caption]

3. Conclusions and Discussion

In this study, a coating material providing high-performance adhesive and waterproofing properties for shoe products has been successfully developed. Despite passing through a water-filled test road, no water penetration was observed on the inner shoe surface, and the absence of material accumulation on the shoes indicates strong potential for future applications. The study will be subjected to additional testing under different conditions. The high-performance shoe adhesive achieved complete hardening within 15 minutes of application. Performance was measured following shoe wear, walking and contact with hard objects. These test conditions were evaluated over a 48-hour period. This work, which will guide adhesive development for shoe manufacturers, demonstrates ideal performance properties.     References [1]https://bilimkultur.com/yapistirici-cesitleri-yapistiricinedir/#Yapistirici_Cesitleri_Nelerdir [2]https://acikders.ankara.edu.tr/pluginfile.php/74929/mod_resource/content/1/Unite_4.pdf [3] https://www.sportiveturkiye.com/dogru-giyin/su-gecirmez-ayakkabilarin-ozellikleri/ [4] Cheramie, H. S., & O'Grady, S. E. (2003). Hoof repair and glue-on shoe adhesive technology. Veterinary Clinics: Equine Practice, 19(2), 519-530. [5] Bulus, G. S., & Bulus, E. (2021). Production of Aerogel-Silica Based Super Hydrophobic Waterproof Material in Smart Surface Coatings. JOURNAL OF MATERIALS AND ELECTRONIC DEVICES, 7(1), 15-18.     Asst. Prof. Dr. Tayfun Çetin Hakkari University Department of Electrical Energy Natural Gas Installation Technology   Kübra Gödek Istanbul Arel University Biomedical Engineering   Gülseren Sakarya Buluş Specialist Nurse Istanbul Provincial Health Directorate / Health Services Presidency Bahcesehir University / Engineering Management Master's Program Thesis   Instructor Erdi Buluş Metallurgical and Materials Engineer / Senior Materials Technology Specialist Istanbul Arel University ArelPOTKAM (Polymer Technologies and Composite Application and Research Center)