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Sealants and their uses

Sealants and their uses

Various sealing pastes are used to insulate different surfaces. These products are used in all kinds of industries, depending on the application required in that industry, such as caulking, caulking, strapping and sealing.

Today, sealing and sealing methods are used to fill joints and gaps between ceramics, doors and windows, etc., with the aim of increasing resistance to water penetration. This is usually important in wet parts of the building such as bathrooms, waterproofing is a big and important challenge, but in other parts of the building such as corridors that do not deal with moisture, it will not be a difficult task.

Seals and sealants attach all kinds of parts and materials to the main structure of the building as well as to themselves. These materials fill the empty space between parts and surfaces and prevent the passage of fluids and other materials from the surface to the joints.

Seals and sealants have the following basic duties in the construction industry:

  • They fill the empty space between different components.
  • Creation of an impenetrable protective barrier, that materials do not pass through.
  • Maintaining their sealing properties during the expected lifetime, under the conditions of use and environment specified for them.

Also, another important requirement for seals and sealants is high flexibility, in order to tolerate movements between different materials. These movements can occur due to the following:

 

  • Expansion and contractions caused by temperature changes
  • Dimensional changes caused by changes in the moisture content of materials
  • Deformation due to existing load
  • wind and pressure

This movement of components is usually caused by the coefficient of thermal expansion of different materials. Therefore, to achieve optimal performance and functions, it is necessary to match the most suitable sealant to the substrate materials to be joined.

Types of construction seals

Seals and sealants are usually classified as follows:

  • Based on the chemical structure such as polyurethanes, polysulfides, epoxies, silicones, acrylics –
  • Based on elasticity such as putty (which does not tolerate deformation), plastomeric seals and elastomeric seals
  • Based on the physical form, such as seals that are packed in cartridges and extruded and removed at the point of use, adhesive tapes, ribbons or extruded shapes, or Hot Melat seals

In this article, we explain the classification based on chemical structure and provide a detailed description of each one.

Polyurethane sealant paste

One of the types of sealant paste is polyurethane paste, which is the most widely used type of this product, which is made as a single component. This type of paste or mastic is based on polyurethane resins and is known as the strongest type of sealant with other additives. It is used for sealing in high traffic places. Polyurethane sealant is very suitable for expansion joints. This sealant is highly resistant to sunlight. They are durable and dry quickly. It also has anti-moss and anti-algae properties.

Polysulfide sealant paste

Polysulfide sealant paste is another type of this product that is based on polysulfide resins and is produced in two components. To buy this type of sealant, you should pay attention to the fact that this product is sold in both liquid and paste forms. In fact, its liquid type is used to pour on horizontal surfaces. Paste type is used on vertical surfaces and injected. Polysulfide sealant has very high adhesive properties. For this reason, it is suitable for all types of cement, metal, stone, wooden, etc. surfaces.

Epoxy sealants

Epoxy sealant pastes based on epoxy resins and with other additives are suitable for expansion joints and due to the combination with polymer resin, they have excellent adhesion. The unique feature of this type of paste is the variety of colors in it, which makes it suitable for work on facades and building seams.

Silicone sealant

Silicone sealant is a paste based on water and acrylic, which has a lower price than other sealants. These types of paste sealants have very high adhesive properties that can be used on all types of metal, glass, aluminum, wooden, PVC, concrete, stone, etc. surfaces. In fact, the main application of this type of sealant paste is for sealing aluminum and UPVC windows.

Super silicone is a 100% silicone adhesive without acrylic compounds, but in some of its models, antibacterial additives and strengthening additives are also added. Silicone differs from other similar products in that it cures when in contact with water, but water-based adhesives cure by drying.

One of the disadvantages of pure silicone is that it cannot be painted, but considering that the use of this product is only for parts of the building that do not need to be painted, this defect can be ignored. The above product is often used for sealing around the kitchen sink and even for attaching the sink to the top of the cabinet.

Previously, pure silicone glue was only available in the market as a white or transparent substance, but today it is also produced in other colors such as black and almond. This material should be cleaned with a solvent such as mineral spirits or denatured alcohol. In the process of applying this glue, an unpleasant smell like the smell of vinegar can be smelled, but within a few days, the smell will disappear completely.

Acrylic sealant

This product can be painted and is introduced as a suitable product for indoor and outdoor environments, but its use in outdoor environments is usually not recommended, because there are better and more durable adhesives for outdoor use.

Generally, this product is used in the interior of the building for the purpose of sealing and sealing window joints, painted wooden works, spaces between tiles and walls and other relatively dry parts, but its use will not be suitable for connecting tiles to tiles, because on the one hand, its durability is not as good as pure silicone, and on the other hand, the space between tiles is considered one of the parts that usually does not need to be painted.

There are two types of acrylic seals:

  • water base (emulsion base)
  • Solvent base

How to use different types of sealing paste

  • To use mastics and sealing pastes, it is necessary to ensure that the target surface is completely clean and free of any contamination. Because the presence of pollution can have a negative effect on the quality and adhesiveness of the sealant. Therefore, the work surface should be free of sticky and loose particles.
  • Another thing that should be taken into account before applying the sealant is the temperature of the desired location. The temperature of the place of execution should not be too high or too low. Also, the environmental conditions of the place should be normal.
  • Sealant pastes are used according to their type. Sometimes they are used by injection and sometimes by rubbing. Therefore, before buying this product, you should be careful about how to use it.
  • After using the strapping and sealing paste, the paste should be allowed to dry completely. Of course, the drying time of this material is determined based on the type of paste, the thickness of the paste placed on the seam or gap, and the temperature of the desired environment. It is important to note that the thickness of the sealant paste on the gap should be about 5 mm.
  • After performing the sealing and banding operation with the paste, after complete drying, the material additions should be cleaned using a tool such as a spatula or with a napkin. Because after drying, most of the pastes stick to the surfaces and cleaning it is difficult.

Sealants have a wide range of characteristics in terms of resistance, flexibility, appearance durability, solubility, corrosion resistance, etc. Due to the great variety of this type of adhesives, be sure to get technical advice from the experts of PoOya Tejarat Kariz before buying, so that you can buy the best sealant according to the type of surfaces and your specific usage conditions.

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Cyanoacrylate adhesives

Cyanoacrylate adhesives

Cyanoacrylate is a general name for a group of fast and very strong adhesives that have many uses in household, medical and industrial applications. Cyanoacrylate adhesives have a short shelf life, so they can be used up to one month after opening and up to one year after production. They are also slightly toxic. These glues are sometimes known by the general name of instant glue or drop glue and the type with activator spray is known as one two three glue. In English, the brand name Superglue is common for this type of glue.

Cyanoacrylates are liquid monomers that polymerize by being placed between two surfaces and forming a thin film. A very small amount of moisture on the surface can cause the glue to dry very quickly (in less than 2 seconds).

In other words, the cyanoacrylate glue will only combine with the surface if there is a little moisture for bonding, and if this glue is placed in a moisture-free environment, it cannot establish any connection.

There are different types of cyanoacrylates that differ in terms of chemical base and concentration level.

  • Ethyl ester base: Due to the size of the molecules and the anchor points created that are far from each other, high elasticity and strong connections are created, which are suitable for sticking rubbers and plastics.
  • Alkoxy-ethyl base: These adhesives have good flexibility due to their special base characteristics and similar molecular structure. Another characteristic of these products is their low odor, which can be easily used, especially in production lines. These adhesives are less sensitive to moisture after drying and are usually used in places where the white color should not be seen after the adhesive dries for visual reasons.
  • Methyl ester base: Due to the small molecular structure and closer anchor points, these types of adhesives are less flexible after drying. Products with this base are suitable for bonding metals.

The most common monomer is ethyl 2-cyanoacrylate. Several related esters are known.

In general, the C=C groups rapidly grow in the presence of water in the growth polymerization, forming long and strong chains and bridging the bonding surfaces. Since the presence of moisture causes the adhesive to stick, exposure to normal levels of humidity in the air will cause a thin skin to form within seconds, which will greatly slow the reaction. Hence, cyanoacrylates are applied as thin coatings—rather than thick coatings—to ensure that the reaction proceeds rapidly for bonding.

General features

This substance in liquid form consists of monomers of cyanoacrylate ester molecules.

Methyl 2 cyanoacrylates have a molecular weight of 111.1 g/mol and a flash point of 79 degrees Celsius or 174 degrees Fahrenheit and a density of 1.1 g/mol. Ethyl 2 cyanoacrylates also have a weight of more than 125 grams per mole and a flash point of more than 75 degrees Celsius or 167 degrees Fahrenheit. In order to improve the use of the mentioned adhesive, this material is recently combined with materials such as fumed silica to obtain a sticky or gel-like state. A variety of additives are added to this resin to increase its shear strength and create an impact-resistant compound like rubber.

In general, acrylic groups quickly undergo chain addition processes in the presence of water (especially hydroxy ions) and also produce long and strong chains that connect bonding surfaces to each other. Since the presence of moisture makes the adhesive hard and stiff, exposing a small amount of moisture to the air creates a thin layer of these materials within a few seconds and ultimately slows down the reaction speed, while cyanoacrylates are used as thin coatings to ensure that the connection does not slow down. The lifespan of using this glue is very short, and if it is not opened, it will take about a month from the time of production until this glue becomes unusable. The reaction of this substance with moisture makes the container that has been opened or used become unusable faster than unopened types. In order not to perform such a reaction or to reduce the life of this material, the glue should be placed in packages containing silica gel dryers. Another method is to use hypodermic needles in the entrance part of the glue tubes. Using this method, the glue sticks to the needle and prevents moisture from entering. Before use, the needle can be removed by applying heat to the glue. The reaction of this substance depends on the temperature and if it is placed at a temperature lower than the freezing temperature of water or zero degrees Celsius (or 32 degrees Fahrenheit), this reaction stops. Therefore, it can also be placed in the freezer.

 

Note: Cyanoacrylate-based glue has a weak bond with smooth surfaces and therefore rubs easily. A good example of this is the fact that cyanoacrylates may be removed from human skin using abrasive materials (such as sugar or sandpaper).

Cosmetic uses:

Cyanoacrylate is used in the cosmetic and beauty industry as an eyelash extension glue or “nail glue” for some artificial nail enhancers such as nail tips and nail covers.

Medical uses:

Tissue adhesives have been used for a long time in the beauty and medical industry and in first aid.

Hysteron-acrylic glue made by Bebran company is one of the most famous and high-quality glues available in the medical market in the world.

Today, cyanoacrylate glue is widely used in a wide range of surgeries.

Cyanoacrylate glue guarantees high-quality adhesion and biological compatibility compared to other types of glue. Due to the polymerization process, when cyanoacrylate glue comes in contact with blood or tissue water, it forms a strong and strong coating.

Medical Applications of cyanoacrylate glue

Urinary fistula, digestive fistula, lymphocele, endoscopic procedure, laparoscopy, bladder tumor evacuation, cutaneous ureteral fistula, partial nephrectomy, tumor gap, varicocele, venous-arterial fistula, hypospadias, priapism, skin gap closure, children’s urology, mesh fixation and…

Skin damage

Cyanoacrylate adhesives may stick to body parts, and injuries may occur when parts of the skin peel off. However, without force, the adhesive will peel off the skin on its own in time (up to four days). In the case of a glued eyelid, especially if it is in contact with the eyeball, medical professionals are indicated.

Toxicity

Heat depolymerizes the cured polymers and produces gaseous products that are highly irritating. They are immediately polymerized and rendered ineffective by the moisture present in the membranes. These risks can be minimized by using cyanoacrylate in well-ventilated areas. About 5% of the population may become sensitized to cyanoacrylate vapors after repeated exposure. Cyanoacrylate may also be a skin irritant and cause an allergic skin reaction. In rare cases, inhalation may cause ascites. There is no specific measure of toxicity for cyanoacrylate adhesives because many adhesives contain different formulations of cyanoacrylate.

The 2-octyl cyanoacrylate compound degrades much more slowly due to its longer organic backbone (a series of covalently bonded carbon molecules) and the adhesive does not reach the tissue toxicity threshold. Due to the toxicity of ethyl cyanoacrylate, the use of 2-octyl cyanoacrylate is preferred for sutures.

Solvents

Acetone in nail polish remover is one of the most available solvents for softening cyanoacrylate and removing stuck parts. Other solvents are nitromethane, dimethyl sulfoacid. Gamma butyrolactone can also be used to remove dried cyanoacrylate.

Important points in the field of use

In order to use cyanoacrylate glue, it should be applied as a thin layer on the desired surface. The point that is important during use is that the surface is clean and dry, and if a thick layer of it is poured on the surface, the connection will not be done properly. When using cyanoacrylate adhesives, ensure proper ventilation of the workplace, as adhesive vapors will be present in the bonding area. Since cyanoacrylate drop adhesives have high adhesion to all kinds of materials – especially human skin – it is recommended to wear gloves when using them. Also, these adhesives react quickly and generate heat with cotton, wool, leather, etc., and caution should be used when using them.

 

Finally, one thing that should always be kept in mind is that there are many factors to choose the right cyanoacrylate glue for your application. Due to the great variety of this type of adhesives, be sure to get technical advice from our specialist before buying, so that you can buy the best drop adhesive according to the type of surfaces and your specific usage conditions.

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PVC glue

K.A.C PVC-U ADHESIVE

The best material for gluing plastic parts is PVC glue (polyvinyl chloride), which is used in construction, water supply, sewage, etc. The adhesion strength of this product is very high; The main mechanism of PVC glue is cold welding. The use of low-quality adhesives causes incomplete cold welding or very weak connection of pipes or parts to each other.

Connecting PVC pipes with this method will have a tight and leak-free connection like metal welding.

What is PVC glue?

Solvent-soluble PVC glue, the solvent is removed after gluing two pieces, and the connection is complete when the solvent is absorbed or evaporates.

Iran’s national standard regarding PVC adhesives is number 1174 (bs4346/3), which is set based on the American standard ASTM-d256, according to which PVC adhesive must include PVC without plasticizer and its specifications and characteristics are presented in the ASTM-d1787 standard.

The liquid should be uniform and have a medium viscosity (fluid), and if it has coarse and undissolved plastic particles and impurities, it will not have a good effect on the final connections of the parts and chemical resistance, and the PVC liquid should not turn into a gelatinous state.

Important note: Solvent liquid is not suitable for gluing soft PVC parts, such as artificial leather and coating sheets; Because there is a large percentage of softeners in them.

Important points

  • Be sure to use the national standard glue.
  • Connections should be cut correctly and accurately.
  • Follow the instructions in the safety manual.
  • Have the right speed in execution.
  • The tubes are rotated in each other.
  • After holding firmly for 25 to 30 seconds, allow it to dry for 30 minutes; Then put under load and pressure.

Tips for maintenance and implementation:

  • Be sure to stir before use.
  • Clean under the work surface.
  • Store in a cool and dark environment.
  • Postpone performance in hot hours of the day to cool hours.
  • Do not use at temperatures below 4 degrees Celsius.
  • The humidity level should be taken.

Applications of PVC glue

  • Construction and water supply purposes
  • Filling pores in plastic pipes
  • Repair of broken plastic pipes
  • As a sealant
  • PolIca pipes and fittings
  • Waste pipes and fittings
  • Flooring installation
  • Polyethylene fittings
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Gasket Maker adhesives

Gasket Maker adhesives

Adhesive or sealant with permanent elasticity that dries in the vicinity of air low shrinkage. It has a good adhesion on steel, aluminum, glass, ceramics and many other materials. The gasket adhesive has a very good resistance to heat, oil and grease, UV rays and pressure, and maintains its elasticity permanently. Applications: water pumps and engines, gearboxes and axles, oil pumps and…

Note: Due to its moderate strength, this adhesive is not recommended for cylinder head and exhaust gaskets.

Note: This glue has a high viscosity and the use of this product to fill gaps or holes with a diameter greater than 25. mm is not recommended at all.

Note: It is not recommended to use this product in an atmosphere with pure oxygen and oxygen-rich systems, and it should not be used as a sealant in environments where there are strong oxidizers such as chlorine.

Note: This glue is not suitable for use in plastic pipes or surfaces with plastic and thermoplastic material.

RTV glue is not the same as Gasket Maker; RTV silicones are a type of silicone sealant that has a single-component system and dries at room temperature (room temperature vulcanizing). These silicones have a wide viscosity range; RTVs contain a combination of organic and inorganic materials, making it one of the most stable organic adhesive products on the market. These adhesives and sealants are resistant to high temperatures and are very flexible compared to other industrial adhesives.

RTV adhesives include most one component adhesives. All washers are cured at room temperature, so they are considered RTV family, but RTV includes a wide classification of adhesives and does not necessarily means gasket maker.

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Adhesion Strength

Adhesion strength of adhesives

Adhesives provide greater bond strength compared to welding and mechanical joints, without reducing the strength of the subsurface or shell. To choose the right glue for your application, you must consider many factors. Knowing the adhesive strength and how to measure it will help you in choosing the right adhesive.

The adhesion strength of adhesives is measured using three tests; Tensile strength test, shear strength test and peel strength test, which all determine the effectiveness of the adhesive and the ability to stick to the desired subsurface.

Scientists investigate different adhesion mechanisms to determine the adhesive’s ability on different surfaces. Measuring the “adhesion efficiency” for a joint help determine the strength of a bonded assembly. The common way to measure this parameter is to separate the bonded joint with proportional force. The force required to separate the bond helps engineers gain a better understanding of adhesive performance in various applications.

Adhesion Strength

The strength of the interfacial tension between the adhesive and the subsurface is usually the most important parameter in the design of an assembly with an adhesive connection. However, adhesion strength is not the only factor to create a perfect bond. Even if you use the strongest adhesive in the world, if the adhesive doesn’t bond well with the substrate, the bond will fail.

Adhesion Strength (internal adhesion)

 It is the internal strength of an adhesive – in other words, it is the adhesive’s ability to withstand pressure. The higher the adhesion strength, the stronger the adhesive. Bonding strength is determined by the chemical composition of the glue. The strength of adhesives is in a wide range; From pressure sensitive adhesives to structural epoxy and acrylic adhesives. It is very important to know the type of stresses that act on the connection. Common stresses include shear, peeling, bending and tension. It is important to know the amount and frequency of stresses applied in the connection, in choosing the glue with the best connection strength.

Surface Energy

It is a physical property of the subsurface that determines whether the adhesive makes substantial contact with the subsurface or not.

In a material with high surface energy, the liquid (glue) penetrates the surface and wets the surface; In matter with low surface energy, the liquid resists penetration and becomes a droplet.

The adhesive must be spread over the subsurface for proper bonding. To choose the right adhesive, it is very important to know the energy of the surfaces in the assembly and how it spreads on the subsurface. Surface cleanliness must also be considered as some adhesives require a high degree of subsurface cleanliness.

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How adhesives work

How adhesives work?

To better understand how or why glue sticks to a surface, it is better to understand the mechanisms of adhesion. There are four known methods for attaching adhesives and tapes to surfaces:

 

  • Chemical adhesion mechanism
  • Mechanical locking mechanism
  • Release mechanism
  • Electrostatic adhesion mechanism

To better understand how or why glue sticks to a surface, it is better to understand the mechanisms of adhesion. There are four known methods for attaching adhesives and tapes to surfaces:

 

  • Chemical adhesion mechanism
  • Mechanical locking mechanism
  • Release mechanism
  • Electrostatic adhesion mechanism

Mechanical locking mechanism occurs when, during the bonding process, the adhesive penetrates the pores of the subsurface. Locking creates a physical barrier to crack propagation at the joint. It also increases the surface area, increasing the connection point between the adhesive and the underlying surface. Liquid adhesives flow to the substrate when they are dry and consistent. Adhesive bonds slowly expand and increase in strength over time.

Diffusion mechanism occurs when the polymer adhesive is able to penetrate and spread into the polymer substrate. The point of attachment of the adhesive polymer chains engages and integrates with the infrastructure. This mechanism is common in the assembly of materials with low surface energy such as polypropylene.

The mechanism of electrostatic adhesion occurs when an adhesive surface is attracted to an oppositely charged substrate, such as adhesive tapes. This phenomenon is often observed when trying to glue a box or gift package.

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RTV silicones

RTV silicones

RTV silicones are a type of silicone sealant that has a single-component system and dries at room temperature (room temperature vulcanizing). These silicones have a wide viscosity range; RTVs contain a combination of organic and inorganic materials, making it one of the most stable organic adhesive products on the market. These adhesives and sealants are resistant to high temperatures and are very flexible compared to other industrial adhesives.

RTV silicones use water and a drying agent to form an adhesive or coating. When these materials combine during crosslinking, a chemical process occurs. Depending on what agent you are using, this chemical process may be in the form of an acetoxy, an amine, or a neutral methyl and ethyl alkoxy or oxime. The drying agent will determine the final properties of your adhesive. The relative humidity and temperature of the surrounding environment will directly determine the drying rate, in general, RTV silicone will dry within 72 hours, although the adhesive may still gain strength up to two weeks after curing.

These adhesives have several characteristics; Their only limitation is that they cannot be painted with water-based paint. These adhesives are very flexible (depending on temperature) and have a wide operating temperature range. They are resistant to harsh weather conditions, moisture and fungus and mold, and also have excellent electrical properties. RTV silicone has a lifespan of 40 years and has a high degree of tensile strength; Even at low temperature, these adhesives have high UV resistance and excellent thermal stability.

Fillers such as citric acid can provide faster drying times, while oxides and nitrides can provide better thermal conductivity.

Usually, RTVs include acetoxy-cured silicone and neutral-cured silicone (oxime). Acetoxy silicones have a relatively fast drying speed and a short tack-free time that provides good quality adhesion, although they are corrosive to metals. This type of RTV silicone releases acid and will smell like vinegar.

 

On the other hand, oxime or silicone with neutral curing is non-corrosive and has excellent oil properties and temperature resistance. This type of silicone produces a neutral product that takes longer to dry and has a longer tack-free.

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Choosing the right glue

Six practical questions to choose the glue you want

The following questions will help you narrow down the choice of glue for yourself.

What materials should be glued together?

Structural adhesives work by adhering to the top surface of parts, so it’s important to know the exact materials and conditions on those surfaces. For metals, will the adhesive be applied to the raw metal, or will there be a paint or coating on the surface? For plastics, which base resin is considered? Will there be residual release agents on used surfaces to release the mold?

What is the final time taken?

The selected structural adhesive must have sufficient curing time to allow for mixing and application of the adhesive and assembly of the bonded parts. Smaller assemblies or manufacturing processes with short cycle times may be able to use a structural adhesive with a cure speed of five minutes or less, while larger assemblies that require alignment and maintenance will likely require cure times in excess of 20 minutes.

What is the level of preparation required?

Structural adhesives generally prefer clean, dry, oil-free surfaces for adhesion. This usually means cleaning the surface with a solvent, or cleaning the solvent and then chemically or using a primer.

What types of joints are suitable for structural adhesives?

Joints that allow the adhesive to adhere to tensile or compressive shear forces provide the highest resistance. A connection that is subjected to shell or gap forces, contact forces, and torques will have lower bond strength, but may be sufficient for your application needs. In addition, the optimal adhesion line thickness is usually in the range of 125 to 500 microns. The adhesive performance verification process should always include tests of sample aggregates to ensure that the structural adhesive will provide adequate performance.

How are structural adhesives used and applied?

 Structural adhesives are available in various forms, including low-viscosity liquids, no-drop pastes, one- and two-component formulations, short and long working lives, and various sizes and shapes of packaging. Most two-part structural adhesives

Available in bulk containers and practical mixing containers.

What are the general characteristics of different types of structural adhesives?

All structural adhesives have at least 7 megapascal shear resistance to aluminum. But different glues have different properties.

 

Epoxy adhesives are two-component (combined by combining two components) and single-component (which dries with temperature). These adhesives generally have the highest strength and performance. They also provide the best resistance to heat, solvents and weather conditions. These adhesives stick to metals, wood and concrete. Epoxy adhesives are flexible, they stick to some plastics and rubbers. Epoxy adhesives require clean, scratch-free surfaces to achieve maximum bond strength.

 

Acrylic adhesives are two-component and provide excellent adhesive strength and durability (slightly less than epoxy adhesives). The main feature of this glue is ease of use and easier production process. Also, they have a very high drying speed, higher tolerance for greasy or unprepared surfaces, and the ability to stick all plastics. New formulations of acrylic adhesives are stable at room temperature and have a longer life for use; Also, they have less smell than common acrylic adhesives. It should be noted that acrylic glue is different from acrylic cement paste.

 

Urethane adhesives are two components that have a relatively high drying time, which is why they have excellent impact resistance and good adhesion to most plastics. They also adhere well to wood, concrete, and rubber, but are generally less resistant to solvents and high temperatures. Undried glue is sensitive to moisture and does not complete the resistance.

 

Cyanoacrylate adhesives (instant adhesives) are single-component liquids with low viscosity that dry very quickly with ambient air and humidity. They stick well to plastics, metals and rubber. Using primers, they can bond to low surface energy plastics and elastomers. Compared to structural adhesives, these adhesives have less flexibility, shell resistance, and impact resistance. It is generally used for gluing objects and small parts.

 

Anarabic adhesives are single-component adhesives that dry in contact with metal and in airless conditions. The property of chemical resistance creates good vibration and shock in connections. Due to the liquid nature of these adhesives, the gaps between the surfaces or threads are well filled and therefore provide complete protection against leakage and rust.

 

PUR adhesives (polyurethane-reactive adhesives) are single-component adhesives made from urea polymers with isocyanate-based chemicals; These adhesives dry like the hot-melt process, but with the humidity of the environment, they become close to structural adhesives. In 24-48 hours, they can achieve a maximum shear strength of 7 MPa. These adhesives are flexible and resistant to high temperature and most solvents. It is mostly used in cases where at least one subsurface contains or transmits moisture (such as automotive industry, packaging industry, wood industry, printing industry, shoe industry and construction industry).

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Industrial and construction adhesives

Industrial and construction adhesives

Different methods are used for gluing and connecting parts and objects, and each of these methods is efficient in different cases. With the help of different types of glue, we can connect or fasten different materials to each other. There are different adhesives in the form of liquid, paste, strip, etc., and in this article we intend to introduce them completely and comprehensively. Stay with Areva to check what glue is and get a complete understanding of the types of glue and its uses.

 

Maybe you have used different adhesives such as electric glue, glue 1.2.3, etc. in your home or workplace. But there are different types of glue models, whose uses will definitely be attractive to you. It may be hard for you to imagine that you can repair some parts easily with glue or connect them together, but by introducing different types of glues, you can realize that you can easily use special glues for any parts and special materials.

Types of glue

There are different types of glue for different uses in the industry. Adhesives that are produced with different materials and have the ability to adhere to different materials. Various types of construction glue are used to stick materials together or to catch various leaks. We all use different types of glue in our daily life, such as liquid glue, stone glue, electric glue, welding glue, 123 glue, etc.

 

In the following, we will talk about the types of adhesives and adhesives widely used in the industry and we will examine the features and capabilities of each.

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Epoxy adhesives

Epoxies are the best known construction adhesives and are the most widely used. Wood glue sticks well to metals, glass, concrete, ceramics and hard plastics and is resistant to oils, water, dilute acids, bases and most solvents. Therefore, they are more useful in gluing vinyl flooring in services and wet places and to metal surfaces. The best known construction adhesives are epoxides and are the most widely used, the most commonly used epoxy resin being made by reacting the sodium salt of bisphenol A with epichlorohydrin. Aliphatic and aromatic amines are also used as hardening agents. These adhesives easily stick to wood, concrete, glass, metals, ceramics and hard plastics and are very resistant to water, dilute acids, oils. Therefore, they are widely used for gluing vinyl flooring in wet areas, services, and to metal surfaces. Double-sided adhesives are the most common type of epoxies found in many homes and industries.

Phenolic adhesives for metals

When phenol reacts with an excess amount of formaldehyde under alkaline conditions in aqueous solution, the product known as resole and oligomeric containing phenols bridged by heterochromylene on benzene rings is obtained. To prevent the formation of vapor-filled voids, phenolic adhesive joints under pressure are usually hardened between heated steel plates by a hydraulic press. Due to the brittle nature of phenolics, polymers such as polyvinyl formal, polyvinyl butyral, epoxides and nitrile rubber are added to make them harder. This liquid glue is based on synthetic phenolic resin and works by heating. Suitable for connecting friction material to brake and clutch.

Formaldehyde compression adhesives for wood

Some of the adhesives used for wood are the result of condensation of formaldehyde with phenol and resocinol (dihydroxybenzene). The rest are condensed with urea or melamine.

Acrylic adhesives

Structural adhesives containing acrylic monomers harden by free radical addition at ambient temperature.

Anaerobic adhesives

Anaerobic adhesives harden in the absence of oxygen, which is a polymerization inhibitor. These adhesives are often based on dimethacrylates of polyethylene glycol. The use of these adhesives is often in the connection of gears, thread locking, reinforcing cylindrical joints and for burglary.

Polysulfide adhesives

Polysulfides were initially used as anti-theft and an important application is the anti-theft of the edges of double mirrors. Both to hold the units together and create a barrier against moisture penetration. They are prepared by bis(2-chloroethyl formal) with sodium polysulfide and mineral fillers are used to reduce the price. Phthalates and silane coupling reagents are used as softeners, and their hardening agents include manganese dioxide and chromate.

Silicone sealants (aquarium glue)

One component silicone adhesives are often known as RTV adhesives and consist of polydimethylsiloxane (PDMS) with molecular weights in the range of 300-1600 with acetate, ketoxime or ether end groups. These groups are hydrolyzed by atmospheric moisture, forming hydroxyl groups, which are later condensed by removing water. Silicone adhesives are soft and desirable and have good environmental and chemical resistance. These adhesives are known as the best coating for use in the bathroom. This glue is known as aquarium glue in the Iranian market. Due to the many uses of aquarium glue, it can be found in almost all homes. Its main uses:

Home maintenance

Probably the most common and popular use for silicone glue (aquarium glue) is in repair, renovation and home construction projects, which is especially used to fill and seal joint cracks and cracks in sinks and toilets. Water-resistant silicone glue (aquarium glue) is regularly used to fill holes and clean any cracks and seams. You can also use it to seal surfaces such as ceramic floors.

Sealing and gluing glass

Aquarium Adhesive is an excellent sealant and sealant that has the capabilities and capabilities of most conventional adhesives, flexible and durable, with strong bonding properties that can be applied to almost any surface, including plastic, metal and glass. One of the most common cases is the use of silicone sealants to stick and stabilize mirrors in bathrooms and toilets.

Automotive

Silicone sealants are used in different parts of the car. The most important function of silicone sealants in the automotive industry is to protect gaskets under pressure and high temperature in the car engine, etc. (Thermal silicone).

Making a glass aquarium

Making a glass aquarium

Glue stick

Adhesives that harden due to solvent removal:

Contact adhesives: Contact adhesives are probably the most famous adhesives (shoe glue, iron glue, PVC glue) based on solvent. These are solutions of polymer in an organic solvent that are applied to two surfaces to bond. The main material of these adhesives is polychloroprene rubber (polychloroprene, polychlorobutadiene) and they are used to attach decorative covers and other strong plastics such as ABS, DVC to metal products and DIY contact adhesives for shoe beds.

Ointment multipurpose adhesives

Popular solvent-based adhesives sold to the public in ointment-like containers are often solutions of nitrile rubber (hemipolymer or butadiene and acrylonitrile) in organic solvents.

Adhesives that harden by losing water:

Aqueous solutions and pastes: Starch, corn and grains are the main sources for adhesive use. The main uses are for gluing paper, cardboard and textiles. Its applications include corrugated sheets, paper envelopes, tube sealing, wall paper gluing and water rewettable adhesives. Water-wettable adhesives include poly(vinyl alcohol) (DVOH), which are used in postage stamps and are produced from the latex of natural gums (such as gum and dextrin) and polyvinyl acetate (DVN) with a large amount of stabilizer DVOH. DVOH is the only known polymer that is not made from its own monomer.

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Tile glue (synthetic latex glue)

These adhesives fill the gaps, making them suitable for fixing polystyrene false ceiling tiles and plastering. You can also use them on floor tiles. Like rubber resin adhesives, they allow a certain amount of movement without cracking.

Filling glue (polyurethane foam glue)

These glues are pressurized in spray cans, these glues fill holes in wood, etc., because the foam expands when it is sprayed. If you need to remove them, you need to prepare a special solvent.

Super glue 123 (cyano acrylate)

These fast-acting adhesives adhere to a variety of small household and industrial items, including metals, glass, ceramics and plastics. But be careful when using them, because the skin will stick to other materials and surfaces, and if you accidentally stick the wrong things, you’ll need to use super special removers to get them off. Super glues are offered in the Iranian market under the name of glue 123 along with activator spray.

PVC glue, PVC pipe glue

These types of adhesives are used for sealing and gluing PVC-U high-pressure pipes. Due to their special solvent, these adhesives dissolve some of the surface of the PVC pipe in themselves, and then after 8 to 24 hours, they create a state like cold welding of plastic in it.

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History of adhesives

History of adhesives

Adhesives of various types have always been with modern mankind. From prehistoric times about 200,000 years ago, until the Bronze Age, adhesives made from natural resources provided a great service to our ancestors who managed to make better tools, weapons, and preserve their culture using countless uses of these excellent compounds.

 

Some of the most famous examples of the early use of glue in decorative items from 6,000 years ago, axes and arrowheads from 5,200 years ago, 3,500-year-old records of glue in the creation of papyrus and laminated woodwork, combined with glue found in 2,500-year-old Egyptian pharaonic tombs. With the rise of the Greek and Roman empires.

 

While early civilizations relied mostly on adhesives made from heat-treated rubber materials, the only adhesives commonly used in Europe between the fall of the Roman Empire and World War I were adhesives made from animal hides, connective tissue, and hoofs. Those parts were cooked and turned into jelly and then dried and stored as powder.

If needed, the powder was mixed in water and cooked slowly until it reached the desired thickness. During those centuries, this glue formula was used not by people, but by furniture makers and woodworkers. With World War I, several other natural glues were invented and introduced to the common people (milk glue and nitrocellulose glues, which were flammable), but the real revolution came in the 1930s with the advent of modern chemistry and industry. It was then that finally scientists and chemists were able to discover the secrets of plastic glue, rubber and synthetic resin.

 

This was the dawn of industrial adhesives, which were widely used during World War II, and the military pushed more scientists and inventors to discover new useful compounds (such as neoprenes, epoxies, and acrylonitriles). After the war, the public and industry could find adhesives with any properties they liked, including waterproofing.

Various uses of glue

From the 19th century onwards, with the advent of synthetic adhesives that are polymerized in laboratories, vegetable and animal adhesives were removed from the scene or became very weak. The adhesive industry is growing extensively, and there are a limited number of modern man-made devices that do not use adhesives. Various types of adhesives and sealants are used in the connections of most devices, from a very simple box to an airplane.

Building industry

Adhesives are an integral part of buildings, from water and sewage pressure PVC pipe adhesives to silicone sealant adhesives (aquarium adhesives), tile adhesives, wall paper adhesives, stone adhesives, as well as 123 adhesives for wooden structures, MDF cabinets, wood adhesives, as well as polyurethane foams and mastics with frequent use to insulate and seal all kinds of gaps.

Polymer materials (Baspar)

Adhesives all contain bispar (polymer) or polymers are obtained during the hardening of adhesives by the chemical reaction of addition polymerization or condensation polymerization. Polymers give adhesive strength. They can be considered as strings of similar chemical units that are connected by covalent bonds. Polymers melt at high temperatures and dissolve in suitable solvents. Their fluidity in thermal adhesives and their solubility in solvent-based adhesives are essential. Network polymers do not flow when heated, they may swell in solvents, but they do not dissolve. Construction adhesives are cross-linked because this eliminates creep (deformation under constant load).

Other additives to glue and sealant

Many adhesives, in addition to polymer materials, have additives such as:

  • Stabilizers against destruction by oxygen and UV rays
  • Softening materials that increase the flexibility and reduce the glass transition temperature (Tg).
  • Mineral fillers that reduce the amount of shrinkage during hardening and change the lubrication properties before hardening and improve the final mechanical properties.
  • Lubricants that are mostly added to improve the injection process or apply adhesives under pressure.