Compound modification technology of the hottest ep

2022-09-22
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Compounding modification technology of epoxy resin application

Abstract: the epoxy resin and curing agent are compounded and modified by physical or chemical methods to increase the varieties of epoxy resin and meet the requirements of practical application. Compounding modification technology is one of the important contents of epoxy resin application technology. The characteristics of the composite modification technology are the cross penetration, characteristic superposition, performance improvement and innovative products between the basic materials involved in the composite modification. The application practice shows that the composite modification technology updates the application concept of epoxy resin, increases the technical content of epoxy system products, and expands the application field of epoxy resin. This paper mainly introduces the compounding between epoxy resins, compounding between epoxy resins and other resins, toughening and strengthening of epoxy resins, copolymerization of epoxy resins and acrylate monomers, compounding between amine curing agents, compounding between amine and phenolic resin, aromatic amine eutectic and anhydride eutectic, etc

key words: epoxy resin curing agent compounding and modification technology

at present, the concept of epoxy resin application technology is undergoing profound changes. The characteristics of epoxy resin cured products (such as adhesion, insulation and low shrinkage), the function of curing agent and curing speed of traditional concepts are impacted by new application concepts. The new concept of epoxy resin application has opened up new ideas, expanded new fields of epoxy resin application, and promoted the new development of epoxy resin application technology

the composite modification technology of epoxy resin application can update the application concept of epoxy resin, add the technical content of epoxy system, explore the new characteristics of epoxy resin system materials, and expand the new market of epoxy resin system products. Generally, the cured bisphenol A epoxy resin has high crosslinking density, high internal stress, and poor flexibility, fatigue resistance, heat resistance and weather resistance. Therefore, epoxy resin and curing agent should be compounded and modified by physical or chemical methods, so as to show the new characteristics of epoxy resin system products more prominently and achieve satisfactory application results. This paper focuses on the practical application of some composite modification technologies and application examples for reference

1. Composite modification of epoxy resin

1.1 Physical method modification

1.1.1 Epoxy resin glue liquid

when manufacturing epoxy resin glue liquid (varnish), two or more epoxy resins with different relative molecular weight can be compounded to obtain the so-called "bimodal" or "multimodal" epoxy resin glue liquid with relative molecular weight distribution. The compounded epoxy resin adhesive can replace foreign fixtures to a certain extent and is in the middle and high-end market. However, in some new materials and fixtures for special materials, there is still a certain gap between the domestic and foreign levels. In the liquid, the epoxy resin with low relative molecular weight is conducive to improving the permeability; The epoxy resin with high relative molecular weight is beneficial to control the fluidity during hot pressing. The process operability of the glue solution is improved and the usability of the product is met

1.1.2. The base material of epoxy coating

when designing the formula of epoxy coating, bisphenol A epoxy resin with different relative molecular weight is often compounded into a mixed base material; Bisphenol A epoxy resin and aliphatic epoxy resin are compounded to make a mixed base material to improve the flexibility and weather resistance of the product; Sometimes electrophilic additives are added to epoxy resin components to improve the workability and usability of the coating

1.1.3. Compounded with other resins

epoxy resin is compounded with unsaturated polyester resin, vinyl ester resin, phenolic resin, furan resin, amino resin, acrylic resin, alkyd resin, polyvinyl butyral and coal tar, and good application results have been obtained. For example, the modified epoxy coal tar mixed base material compounded by physical methods takes into account the characteristics of epoxy resin and coal tar, and the anti-corrosion effect of the film is excellent. Generally, one other resin added to epoxy resin can account for 30% - 60% of the total resin after complex modification

epoxy resin amino resin acrylic resin is compounded into a ternary system varnish. See table-l and table-2 for its composition and film forming properties

TABLE-1 composition and mechanical properties of ternary system varnish [note]

-

Formula 1

formula 2

formula 3

formula 4

composition

-

-

-

-

E-44 epoxy resin

22

22

17

13

acrylic resin

46

56

56

60

amino resin liquid

32

22

27

mechanical properties

-

-

-

impact resistance/n · cm

441

490

441

49 0

flexibility/mm

/

/

/

/

adhesion/grade

/

/

/

/

note: without catalyst, the curing condition is 180 ± 5 ℃/10min

table-2 chemical resistance of ternary system varnish film

Project

test results

Project

test results

10% saline immersion for 15 days

no change

120 ×× Gasoline immersion 15d

no change

5% hydrochloric acid immersion 15d

no change

soybean oil immersion 15d

no change

5% acetic acid immersion 15d

no change

rapeseed oil immersion 15

no change

10% sodium hydroxide immersion 15d

no change

water boiling 8h

no change

soaking in industrial alcohol for 2D

the paint film is slightly soft

soaking in toluene for 2D

the paint film is slightly soft

made of epoxy resin amino resin propylene The coating film obtained from the ternary system varnish compounded with acid resin has good mechanical properties, ester alkali resistance and boiling water resistance. However, the crosslinking density of the film should be increased to improve its solvent resistance

1.1.4. Toughening and strengthening of epoxy resin

the toughening, strengthening and compounding modification technology of epoxy resin has made new breakthroughs. Domestic 1 has been in the laboratory research stage, introducing new application varieties for epoxy system, expanding new markets, and promoting the new development of application technology of epoxy resin. Toughened or reinforced epoxy system products have become leading materials in many fields, fully showing the vitality of composite modification technology

toughening agent is a compound (or polymer) that can react with epoxy resin or curing agent. The impact toughness, fracture elongation and flexibility (elasticity) of the cured product are significantly improved

according to the application technical requirements, a variety of epoxy series products with excellent performance and meeting the application requirements can be prepared by properly selecting the type and dosage of toughening agent and adopting scientific and reasonable compounding technology. For example, take 100 parts of E-51 epoxy resin, 35 parts of carboxyl terminated nitrile-2l, and 10 parts of 2-methyl-4-ethyl imidazole to form the epoxy adhesive solution toughened by nitrile rubber. When bonding steel to steel, the shear strength is 46.5mpa at room temperature after curing at 120 ℃/3h. If the adhesion promoter is added to the epoxy system toughened by nitrile rubber, the bonding strength to ABS and other plastics can be significantly improved

in addition to the above toughening agents, rigid inorganic fillers or thermoplastic polymers and other toughening materials can be added to the epoxy system, which will also toughen the epoxy cured products

reinforcing agent can improve the strength properties of epoxy cured products. The reinforcing agent (or reinforcing material) used in epoxy resin is mainly fiber, and sometimes whiskers and fillers with reinforcing effect are used. The use of glass fiber, carbon fiber and organic fiber can significantly improve the strength properties of epoxy resin materials

the difference between various fiber electronic universal testing machines and tensile testing machines is that the composite material composed of universal and tensile dimension and epoxy resin has the characteristics of low density, high fatigue strength, excellent vibration damping, good corrosion resistance, dielectric property, electromagnetic wave permeability and heat resistance. At the same time, the composites have anisotropy and designability of material properties

table-3 performance comparison of several engineering materials

material name

density/g · cm-3

tensile strength/gpa

tensile modulus/× 102gpa

specific strength/mn · m · kg-1

specific modulus/mn · m · kg-1

steel

7.8

1.03

2.1

0.13

27

aluminum alloy

2.8

0.47

0.75

0.17

27

titanium alloy

4.5

0.96

0.14

0.21

25

glass fiber composite

2.0

1.06

0.4

0.53

20

high strength carbon fiber/epoxy composite

1.45

1.5

1.4

1.03

97

high modulus carbon fiber/epoxy composites

1.6

1.07

2.4

0.67

150

aramid fiber/epoxy composites

1.4

0.8

1.00

57

boron fiber/epoxy composites

2.1

1.38

2.1

0.66

100

boron fiber/aluminum composites

2.65

1.0

2.0

0.38

57

See table-4 for the mechanical properties of composites made of glass fiber, carbon fiber, aromatic polyamide fiber (also known as Kevlar fiber) and epoxy resin

table-4 comparison of mechanical properties of several fiber-reinforced epoxy unidirectional composites

Project

Kevlar-49

e glass fiber

t-300 carbon fiber

fiber volume content/%

60

60

0o tensile strength/mpa

1.38

2.05

1.55

0o tensile strength/mpa

1380

1100

1240

0o tensile modulus/gpa

72.4

39.3

131

elongation at break/%

1.8

2.8

1.11

Poisson's ratio

0.34

0.3

0.25

therefore, if the long-term characteristics such as strength and stiffness values are not used, 0o compressive strength/mpa

276

586

1100

0o compressive modulus/gpa

72.4

39.3

131

90o tensile strength/mpa

27.6

34.5

411.4

90o tensile modulus/gpa

5.5

8.96

6.2

90o compressive strength/Mpa

138

138

138

90o modulus of compression/gpa

5.5

8.96

6.2

in-plane shear strength/mpa

44.7

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