The use of acidic glass adhesive and neutral weather resistant adhesive in shielding composite materials

1、 Characteristics and selection of adhesives

1. Epoxy adhesive: It is widely used in the electronics industry due to its strong versatility, excellent adhesion, wide adaptability, easy use, good electrical performance, and aging resistance.

2Organic silicone gelSuitable for occasions that require flexibility, wide temperature range, high frequency, high temperature, and atmospheric pollution.

3. Hot melt adhesive: Hot melt adhesive can be used under conditions that require fast assembly, low strength, and low working temperature.

4. Acrylic adhesive: The selection of acrylic adhesive is mainly based on their excellent electrical properties, stability, good aging resistance, transparency, and ability to cure quickly.

5. Polyurethane adhesive: remains soft, tough, and firm from low temperature to 121 ° C.

6. Pre coated polyvinyl butyral: can form tough and easy to assemble joints.

2、 The main applications of adhesives in microelectronics

1. Tube core bonding;

2. Adhesive bonding between circuit components and substrates;

3. Encapsulation. Another main application is printed circuit boards. Due to the requirement to withstand a welding temperature of 250 ° C, the use of adhesives for bonding steel foils to laminated printed circuit boards is limited.

3、 The main applications of adhesives in industrial control equipment

For example, generators, transformers, and other equipment that operate at high temperatures, as well as equipment that must operate in harsh environments and high temperature conditions for 20-40 years. The size of many devices eliminates the possibility of oven curing. And the thermal conduction of copper and other metals makes local heating impossible to achieve. Therefore, it is necessary to use adhesives that cure at room temperature.

4、 The main applications of adhesives in electronic devices

Adhesive applications can be found on almost all electronic devices, such as the bonding of radar antenna composite materials, providing thermal and electrical conductivity for the operation of electronic components. And there is also the bonding of the missile front cone ring. Typical applications include:

(1) Antenna reflectors used for tracking/illuminating radar in ship air defense systems;

(2) Cobra DaYe phased array radar system from Denmark, used for bonding external dielectric windows to substrates in the United States;

(3) Drill and connect various electronic components of Trident MKs missile guidance computer with thermal conductive adhesive film;

(4) In air traffic control radar, the cured epoxy laminate is bonded to the metal frame.

5、 The main applications of adhesives in printed circuit boards

Printed circuit boards, whether rigid or flexible, cannot do without adhesives.

For epoxy glass panels, formaldehyde formaldehyde, nitrile phenolic or modified epoxy can be used, with a maximum operating temperature of about 150 ° C. When used at a high temperature of 260 ° C, glass organic silicon laminated board or copper/polytetrafluoroethylene composite board should be used.

The laminated assembly of rigid printed circuit boards can be coated with thermoplastic orThermosetting adhesiveThe plastic film is bonded together.

Sometimes complex assembly parts require thin, flexible printed circuits. In this case, RTV silicone rubber coating can be used not only as an insulation coating, but also to reduce vibration, which can increase unwanted fatigue loads on the welded joints.

In addition, apply epoxy adhesive and organic silicone on the stressed components to reduce the impact and vibration.

Silicone adhesive

The English name for silicone adhesive is SILICONE, which is a product of organic silicon. It is mainly divided into deacetylation type, dealcoholization type, deamination type, and oxime removal type. Glass glue is commonly known as silicone glue, because users purchase silicone sealant mainly for bonding and sealing glass, so it is called glass glue. The chemical composition includes polydimethylsiloxane, and polymers of silica can be called silicone. Silicone adhesive is a material similar to ointment that solidifies into a tough rubber like solid upon contact with moisture in the air.

1、 Classification of Silicone Adhesive

Single component and two-component.

The curing of single component silicone adhesive relies on the change in physical properties caused by contact with moisture in the air;

Two component refers to the silicone adhesive being divided into two groups, A and B. Either group alone cannot form a cure, but once the two groups are mixed, they will solidify.

The common one in the market is single component silicone glass adhesive. Single component silicone glass adhesives are divided into two types based on their properties: acidic adhesives and neutral adhesives. Acidic glass adhesive is mainly used for general bonding between glass and other building materials. Neutral adhesives overcome the characteristics of acidic adhesives corroding metal materials and reacting with alkaline materials, thus having a wider range of applications and a slightly higher market price than acidic adhesives. A special type of glass adhesive on the market is silicone structural sealant, which is directly used for metal and glass structures or non structural bonding assembly of glass curtain walls. Therefore, its quality requirements and product grade are the highest among glass adhesives, and its market price is also the highest.

1. Mainly used for structural or non structural bonding assembly between metal and glass in glass curtain walls.

2. It can directly connect glass with the surface of metal components to form a single assembly component, meeting the design requirements of curtain walls with fully hidden or semi hidden frames.

3. Structural bonding and sealing of insulating glass.

2、 The use of silicone adhesive

1. Usage: Single component silicone glass adhesive can be used immediately. It can be easily removed from the bottle with a glue gun and its surface can be trimmed with a spatula or wood chips.

2. Adhesive Time: The curing process of silicone adhesive develops from the surface inward, and the surface drying time and curing time of silicone with different characteristics are not the same (please refer to the "Technical Parameters" in Chapter 4 for detailed instructions on curing time). Therefore, if surface repair is to be carried out before the glass adhesive surface dries (acidic adhesive and neutral transparent adhesive should generally be within 5-10 minutes, and neutral variegated adhesive should generally be within 30 minutes). If using color separation paper to cover a certain area, after applying glue, be sure to remove it before the outer layer is formed.

3. Curing time: The curing time of glass adhesive increases with the increase of bonding thickness. For example, a 12mm thick acidic glass adhesive may take 3-4 days to solidify, but within about 24 hours, a 3mm outer layer has already been cured. When bonding glass, metal, or most wood, it has a peel strength of 20 pounds per inch after 72 hours at room temperature. If the area where glass glue is used is partially or completely sealed, the curing time is determined by the tightness of the seal. In an absolutely sealed place, it is possible to remain uncured forever. If the temperature is increased, the glass glue will soften. The gap between metal and metal bonding surfaces should not exceed 25mm. Before using the bonded equipment in various bonding situations, including sealed conditions, a comprehensive inspection of the bonding effect should be conducted. During the curing process of acidic glass adhesive, a smell will be generated due to the volatilization of acetic acid. This smell will disappear during the curing process and there will be no odor after curing.

4. Adhesive bonding:

A. Completely wipe the metal and plastic surfaces clean, remove oil stains, and then use sandpaper to polish the rubber surface, except for rinsing the entire surface of the plastic with acetone first, and then wipe it with acetone. Please follow the precautions for using acetone solvent.

B. Apply glass glue evenly on the surface of the prepared object. If you want to bond two surfaces together, you can first position one side and then apply enough force to squeeze out the other side to expel air, but be careful not to squeeze out the glass glue.

C. Place the bonding device at room temperature and wait for the glass adhesive to cure.

5. Sealing: When using silicone glass adhesive for sealing, follow the same steps as above. Squeeze the glass adhesive forcefully into the joint surface or gap to ensure full contact between the glass adhesive and the surface.

6. Cleaning: Before the glass adhesive is cured, it can be wiped off with a cloth or tissue. After curing, it must be scraped off with a scraper or wiped with solvents such as xylene and acetone.

3、 Application fields of different silicone adhesives

Acidic glass adhesive

1. Suitable for sealing, blocking, leak proof, and weather resistant purposes, both indoor and outdoor are suitable (indoor effect is better), with significant anti-seepage and leak proof effects.

2. Adhesive bonding of various interior decorations of automobiles, including metal, fabric, organic fabric, and plastic.

3. Gaskets for joining heating and cooling equipment.

4. Install non threaded ribs, nameplates, and painted plastic materials on metal surfaces.

5. Seal the windows on the oven door, the flues on gas appliances, pipe joints, and channel doors.

6. Provide instant formed leak proof pads for gearboxes, compressors, and pumps.

7. Seal the ship's cargo hold and windows.

8. Sealing of trailer and truck cab windows.

9. Adhesive and sealing equipment components.

10. Form an anti-wear coating.

11. Embedding and filling thin metal sheet laminates, pipeline networks, and equipment casings.

Neutral weather resistant adhesive

1. Suitable for weather resistant sealing of various curtain walls, especially recommended for glass curtain walls, aluminum-plastic panel curtain walls, and stone dry hanging weather resistant sealing;

2. Sealing of joints between metal, glass, aluminum, ceramic tiles, organic glass, and coated glass;

3. Sealing of joints on surfaces of concrete, cement, masonry, rock, marble, steel, wood, anodized aluminum, and painted aluminum. In most cases, primer is not necessary.

Silicone structural adhesive

1. Mainly used for structural or non structural bonding assembly between metal and glass in glass curtain walls;

2. It can directly connect glass with the surface of metal components to form a single assembly component, meeting the design requirements of curtain walls with fully hidden or semi hidden frames;

3. Structural bonding and sealing of insulating glass.

4、 The development trend of silicone adhesive

Silicone structural adhesive is a high-end adhesive sealing material based on hydroxyl terminated siloxane polymer and multifunctional siloxane crosslinking agent, prepared through compounding, mixing, homogenization and other processes. It has room temperature curing (RTV) and elastic bonding function. It has excellent high and low temperature mechanical properties and aging resistance. It is packaged as a single component, cured quickly, easy to use, and stored stably. It occupies an important position in the markets of building waterproofing, door and window and curtain wall structural glass assembly, and building decoration. With the breakthrough of silicone sealant product technology and the localization of production equipment in China, the number of production enterprises has continued to increase in the past decade. The variety and output of products have grown rapidly, and market competition has become increasingly fierce, showing a tendency towards low price and cost competition. Enterprise profits have been declining year by year, especially when the supply of raw material monomers suddenly becomes scarce and prices increase exponentially. Some production enterprises cannot bear the dual pressure from upstream and downstream and can only exit the market. However, some strong enterprises that value technological innovation can transform unfavorable factors and continuously expand the market with high-quality and cost-effective products and new functional products. China is a developing country, and housing construction (especially curtain walls) is in a period of continuous growth. The total demand for building sealants is still increasing. Faced with the constantly growing market, low-cost competition can only be a short-term market behavior. Only by emphasizing quality and technological innovation can it develop steadily in the construction market.