**2. Major appliances**

Those requiring glass bonding are described as follows.

## **2.1 Refrigerator**

Refrigerator is one of the items that can adopt glass bonding applications for various and different designs in terms of shape and function such as one door, two door, triple door, double door, French door, chest type, upright type, freezer, and kimchi refrigerator. They all can adopt glass plate bonding applications such as all front doors, inclined area between double and two triple doors, and water dispenser area on a front door and control panel. The most popular glass bonding application is a front glass plate bonding to the plastic door chassis. The below **Figure 1** shows a glass plate bonded to front door and a glass plate bonded from side view [1].

## **2.2 Washing machine**

**Figure 7.**

**Figure 8.**

**294**

*Glass bonding for styler.*

*Glass bonding for kitchen ventilation hood.*

*Advanced Functional Materials*

Washing machine has a few application areas that can adopt glass plate bonding applications in terms of shape and function such as top loading, front loading, and combined top and front loading, and they all can adopt a printed glass plate bonding application including control panel area. The most popular application is a glass bonding of top cover to plastic cover frame for top loading washing machine. Front loading type has a door assembled with glass and plastic frame by screws. This structure can be assembled by using a special structural adhesive eliminating screws and its related extra process to use screws. The combined front loading (on top) and top loading (on the bottom) has a function of washing clothe at the same time. The top loading type washing machine in the bottom part slides out front and do the washing. Other application is for bonding of a glass door frame to a glass door for the function of opening and throwing in a forgotten laundry while the washing machine is already running. The below **Figure 2** shows a glass bonding of top cover to plastic frame for top loading washing machine [2].

#### **2.3 Microwave**

Microwave has a few glass plate bonding applications. The most popular application is for bonding of front glass plate to outside front plastic door. Other applications are for bonding of glass plate to inner front metal door frame. One more application for a high-end microwave is for bonding of glass plate to bottom body frame. The below **Figure 3** shows a front door glass bonding to plastic door frame [3].

#### **2.4 Cook top**

Cook top uses an electrical coil with ceramic glass placed on top where they put pots and pans to cook food instead of using gas. The coil generates heat that transfer through a ceramic glass to food. It is a much more high-end image with a sleek design for easier cleaning and better health, and it has a safety advantage during cooking as people can wipe out contamination easily and do not need to inhale the burning gas. The most popular application is for bonding of ceramic glass to ceramic-coated metal frame. Other application is for bonding of ceramic glass to inner metal chassis. The below **Figure 4** shows a ceramic glass that is bonded to metal ceramic coating surface and to metal chassis [3].

### **2.5 Air conditioner**

Air conditioner has a different type of design that can adopt glass plate bonding in terms of shape and function such as window type, wall type, standalone vertical type, and ceiling type. The most popular application is for bonding of a glass plate to plastic frame for wall type air conditioner. This type of application needs a reliable bonding solution as the glass might fall off from air conditioner and cause a safety problem for people if an improper solution is used. The below **Figure 5** shows a glass bonding to plastic frame of wall type air conditioner [4].

chemical reaction is required. But at the same time, it requires a high labor-

*Global Trend of Glass Bonding for Appliance Industry Assemblies*

*DOI: http://dx.doi.org/10.5772/intechopen.90515*

issue [6].

**3.2 Mechanical fastener**

make an automation assembly line, too [7].

**3.3 1 component RTV silicone**

and manpower cost [8].

**297**

**3.4 Polyurethane hot melt**

intensive pre-work such as priming the surface with a primer to improve a bonding durability. It also requires a peel-off of release paper on one side and place the sticky part on the application area mostly manually. It is very difficult to re-adjust the location once it is placed on the substrate, and very high labor cost is required if it has to be re-adjusted. It has to be pressed for a certain amount of time; otherwise, there is no good affinity achieved between the sticky surface of tape and the substrate. The de-bonding happens when bonding a surface not completely flat. Tape solution also generates a bulky waste of release paper. Tape solution tends to release the bonding property under aging condition; therefore, a gap is generated in the glass bonding area as time goes causing a repair. The adhesion of tape is the surface temperature dependent; therefore, if the temperature of assembly line, tape, and substrate was not properly controlled, especially in the winter time due to the effect of cold temperature on the bonding durability of tape, it generates a poor adhesion to substrate and consequently a bonding failure, scrap, and liability

This technology has been available with a history of mankind for a very long time. This can provide a very fast mechanical fixture and consequent assembly, but at the same time, this requires mechanical fasteners and drilled thread holes on both parts, and operator has to assemble them by using fastening tools manually. The assembly leaves a screw mark that is not good in appearance and it is also difficult to

This technology is a room temperature vulcanized (RTV) silicone that reacts with moisture in the air and substrate, and generates some by-products such as oxime, alcohol, acetic acid, and acetone. This technology in general has a high viscosity with a slow curing property that takes a few days for functional bonding and more than 1 week for a complete curing. Normally this technology requires mechanical clips or double-sided tapes for initial fixture time and a stacking space and lengthy curing time before it goes to the next process. Some process adopts 1 component RTV silicone or double-sided tape which requires more manual process

This technology is at first a thermoplastic (remeltable) material that contains some free isocyanate groups, and then, it is similar with 1 component polyurethane technology that reacts with moisture to form a tough thermoset (not meltable) plastic material. Its initial thermoplastic property can melt easily and provide a very excellent high position tack capability that can hold the two substrates in place by losing an energy from molten liquid state, and also its thermoset property provides a high temperature heat and creep resistance with a good durability. Polyurethane hot melt is available with a wide range of open time. This technology has a good adhesion and is compatible with a wide variety of substrates. It has better bonding strength performance and environment resistance compared to normal hot melt due its cross-linked chemical reaction property. It has a relatively lower operation temperature around 120°C; therefore, a dispensing at lower energy is possible. It also has longer open time 1–4 min; therefore, it has a wide bonding window for

#### **2.6 Dish washer**

Dish washer has a different type in terms of shape and function that can use a glass bonding application such as table top, built in stand-alone type, and drawer type that can adopt glass bonding application in the front side. The most popular application is for bonding of glass plate to plastic front door for stand-alone type. The below **Figure 6** shows a glass bonding for stand-alone type washing machine [5].

#### **2.7 Kitchen ventilation hood**

Kitchen ventilation hood can have three glass plate bonding application for its function of easy cleaning of contamination from cooking and high-end image and appearance. This type of design has the glass plate in the middle which is in a closed state. When it is turned on, the glass plate in the middle opens up and the fan inside sucks those fumes, smokes, and microparticles generated during cooking. For a situation where the glass plate is contaminated with oil due to splash of boiling oil during cooking, it can be wiped off easily for clean surface. The most popular application is for bonding of glass plate to moving chassis. Other applications are for bonding of glass to control panel chassis and bonding of glass to other chassis. The below **Figure 7** shows an overall glass bonding area of kitchen ventilation hood.

#### **2.8 Styler**

Styler has a glass plate bonding application such as bonding of glass plate to plastic frame on the front side of it. It is a stand-alone type and has a function of eliminating dust by vibrating the clothe, deodorization by vacuum fan, sterilization by steam heating, and ironing of the clothe by heat pressing overnight inside it and next day they can take it out of the styler and put it on. The below **Figure 8** shows a glass bonding in front of styler.
