What Is a Polymer Adhesive?
Gluing (bonding, bonding, cementing, gluing) refers to the technology of bonding the surfaces of homogeneous or heterogeneous objects with an adhesive. It has the characteristics of continuous stress distribution, light weight, or sealing, and low process temperature. . Gluing is particularly suitable for the connection of different materials, different thicknesses, ultra-thin specifications and complex components. Glue has the fastest development in recent generations, and the application industry is extremely wide. There are many classification methods of adhesives. According to the application methods, they can be divided into thermosetting, hot-melt, room temperature curing, and pressure-sensitive types. According to the application object, they can be classified into structural, non-structural, or special adhesives. It is water-soluble, water-emulsion, solvent-based, and various solid-state. Synthetic chemists often like to classify adhesives according to their chemical composition.
Adhesive
(An adhesive)
- Chinese name
- Adhesive
- Foreign name
- adhesive
- Referred to as
- gum
- Application
- Business factory
- Gluing (bonding, bonding, cementing, gluing) refers to the technology of bonding the surfaces of homogeneous or heterogeneous objects with an adhesive. It has the characteristics of continuous stress distribution, light weight, or sealing, and low process temperature. . Gluing is particularly suitable for the connection of different materials, different thicknesses, ultra-thin specifications and complex components. Glue has the fastest development in recent generations, and the application industry is extremely wide. There are many classification methods of adhesives. According to the application methods, they can be divided into thermosetting, hot-melt, room temperature curing, and pressure-sensitive types. According to the application object, they can be classified into structural, non-structural, or special adhesives. It is water-soluble, water-emulsion, solvent-based, and various solid-state. Synthetic chemists often like to classify adhesives according to their chemical composition.
- Adhesive: A kind of natural or synthetic, organic or inorganic substances that can connect two or more pieces or materials together through interface adhesion and cohesion Adhesive, also called adhesive, is customarily referred to as glue. In short, an adhesive is a substance that enables the adherends to stick together through adhesion. "Adhesive" is a common standard term and also includes some other glues, cements, glues, pastes, etc.
- Bonding substance
- The bonding substance is also called sticky material, which is the basic component in the adhesive and plays a cohesive role. Its properties determine the performance, use and use conditions of the adhesive. Generally, various resins, rubbers and natural polymer compounds are commonly used as bonding substances.
- 2. curing agent
- A curing agent is a component that accelerates the curing of a sticky substance through a chemical reaction. The resin in some adhesives (such as epoxy resin) can not become a hard solid itself without the curing agent. The curing agent is also the main component of the adhesive, and its properties and dosage play an important role in the performance of the adhesive.
- 3.Toughening agent
- Toughening agents are components that improve the toughness of the adhesive layer and increase its impact strength. Commonly used toughening agents are dibutyl phthalate and dioctyl phthalate.
- 4. Thinner
- Thinner, also called solvent, mainly plays the role of reducing the viscosity of the adhesive, in order to facilitate the operation and improve the wettability and fluidity of the adhesive. Commonly used organic solvents for diluents are acetone, benzene and toluene.
- 5.Filling
- Fillers generally do not undergo a chemical reaction in the adhesive. It can increase the consistency of the adhesive, reduce the coefficient of thermal expansion, reduce shrinkage, improve impact strength and mechanical strength. Commonly used fillers are talcum powder, asbestos powder and aluminum powder.
- 6. Modifier
- Modifiers are components that are added in order to improve the performance of certain aspects of the adhesive and meet special requirements. For example, to increase the bonding strength, a coupling agent can be added, and a preservative, antifungal agent, and Fuel and stabilizer. [1]
- There are many types of adhesives. A simple classification of adhesives according to different standards is as follows.
- 1.According to the chemical properties of adhesives, they can be divided into inorganic adhesives and organic adhesives. For example, water glass, cement, gypsum, etc. can be used as inorganic adhesives, and polymer materials are used as adhesives. The adhesives are all organic adhesives.
- 2.According to the physical state of the adhesive, it can be divided into liquid, solid and pasty adhesives. Among them, solid adhesives are powdery and filmy, while liquid adhesives can be divided into aqueous solution and organic. Solution type, water emulsion type and non-aqueous medium dispersion type.
- 3. According to the source of the adhesive, it can be divided into natural adhesives and synthetic adhesives. For example, natural rubber, asphalt, rosin, gelatin, cellulose, starch glue, etc. are all natural adhesives, which are artificially synthesized by polymerization. All kinds of adhesives belong to the category of synthetic adhesives.
- 4. For common organic adhesives, they can be divided into thermoplastic resins, thermosetting resins, and rubber adhesives according to their molecular structure.
- 5. According to the application method of the adhesive, it can be divided into pressure-sensitive adhesive, re-wet adhesive, instant dry adhesive, delay adhesive and so on.
- 6. From the temperature range of the adhesive, it can be divided into high temperature resistant, low temperature resistant and normal temperature used adhesives; and according to its curing temperature, it can be divided into normal temperature curing, medium temperature curing and high temperature curing adhesives. Adhesive.
- 7. According to the application field of adhesives, adhesives are mainly divided into civil construction, paper and plants, automobiles, aircraft and ships, electronics and electrical, and medical and health adhesives.
- 8. The chemical composition of the adhesive can be divided into various specific types of adhesives, such as epoxy adhesives, polyurethane adhesives, polyvinyl acetate adhesives, and the like.
- 9. Hardened adhesive, polyurethane adhesive, epoxy adhesive, sealant, hot melt adhesive, potting adhesive, organic silicone, conductive adhesive, pressure-sensitive adhesive, white latex, universal adhesive, anaerobic adhesive, polyamide adhesive, laminating adhesive , Penetrating glue, Waterproof glue, Fireproof glue, Special glue for speakers, Special glue for automobiles, Special glue for electronics and electrical appliances, Photosensitive glue, Special glue for buildings, Special glue for solar energy, Special glue for auto maintenance, Self-adhesive, Double-sided tape, Silicone Glue and so on.
- Thermoplastic
- Cellulose esters, olefinic polymers (polyvinyl acetate,
- The basic points considered by the above bonding theory are related to the molecular structure of the sticky material and the surface structure of the adherend and the interaction between them. From the adhesive system failure experiments, there are four different situations when the adhesive failure occurs: 1. Interface failure: the adhesive layer is completely separated from the surface of the adhesive (the adhesive interface is completely separated); 2. cohesive failure: the failure occurs in the adhesive Adhesive or adherend itself, but not between the adhesive interface; 3. Mixed failure: Both the adherend and the adhesive layer itself are partially destroyed or only one of the two. These failures show that the adhesive strength is not only related to the force between the adherent and the adherend, but also to the force between the molecules of the polymer adhesive.
- The chemical structure and aggregation state of polymer molecules strongly affect the bonding strength. Studying the molecular structure of the adhesive base is very important for the design, synthesis, and selection of adhesives.
- Because there are many types of adhesives and adherends, the bonding processes used are not exactly the same, and can be divided into: the preparation of adhesives; the surface treatment of adherends; coating; Place, so that low molecular substances such as solvents evaporate the gel; superimposed pressure; remove the adhesive remaining on the surface of the product.
- Notes on Adhesive Selection
- 1. Storage period
- a. Each product has a shelf life. According to international and domestic standards, the shelf life is at room temperature (24 ° C). The acrylic adhesives were 20 ° C.
- b. For acrylic products, the higher the temperature, the shorter the storage period.
- c. For water-based products, if the temperature is below -1 , it will directly affect the product quality.
- 2. strength:
- a. There is no universal glue in the world. For different adherends, it is best to use special adhesives.
- b. For the strength of the adherend is low, then it is not necessary to choose high-strength products, otherwise, the large materials are used small and the cost is increased.
- c. We should not only focus on high initial strength, but also consider good durability.
- d. High temperature curing adhesive performance is much higher than room temperature curing. If high strength and durability are required, high temperature curing adhesive should be selected.
- e. Except for emergency or small area repair and continuous production, a cyanoacrylate adhesive (502 super glue) is not suitable for materials that require high bonding strength.
- 3. Other
- a. White latex and urea formaldehyde cannot be used for sticky metals.
- b. Adhesives requiring transparency. Polyurethane glue, optical epoxy glue, saturated polyester glue, and polyvinyl acetal glue can be selected.
- c. The adhesive should not be corrosive to the adherend. Such as:
- The development of adhesives has entered a long historical process. The use of adhesives by humans can be traced back to a long time ago. From archeological excavations, it was found that as far back as 600 years ago, humans reconciled water and clay, used as adhesives, made ceramics and bricks, and bonded solids such as stones into living appliances. China is one of the earliest countries to discover and use natural adhesives. In ancient times, there was the story of Huangdi cooking glue. Some ancient books have traces about the manufacture and use of adhesives, which is enough to prove that China has a long history of using adhesives.
- With the improvement of production and living standards, ordinary molecular structure adhesives are far from satisfying people's applications in production and life.
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