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The Insulating glass materials and quality control①


With the development of national society and economy, people have higher and higher requirements for building materials. Energy-saving and environmental protection have become the mainstream of the times. The application and development of insulating glass have gradually been recognized and accepted by people, and they have quickly entered people's daily lives. Insulating glass production and related materials industries have been developing by leaps and bounds. Jinan LIJIANG Glass, as one of the first equipment manufacturers to join the deep processing and manufacturing industry of insulating glass, expressed the following opinions on the current status of insulating glass.

Development and current situation of insulating glass 

Insulating glass is a glass product that is separated by support between two or more layers of glass at a distance, and the periphery is sealed, and the space forms a dry gas. Insulating glass is an important external maintenance structure of a building-the most important component of doors and windows. Has the unparalleled characteristics of other products:

1. Excellent heat insulation performance and its thermal conductivity K value are less than 0.3.

2. Good sound insulation performance, can reduce noise by 30~50clb,

3. Since the inner space of the hollow glass is dry gas or inert gas, it has superior permeability, and when the inner space is equipped with decorations, it has a variety of decorative properties.

4. When the temperature difference between inside and outside is great in winter, the inner glass will not be frosted or dew.

Insulating glass production process and regulations 

At present, there are two ways to make insulating glass globally: double-channel sealing groove aluminum type and rubber strip type (Swwiggle), of which the double-channel sealing groove aluminum type production process accounts for 80%, and the rubber strip type production process accounts for about 20%.

1. Production process, equipment, and technical points through aluminum insulating glass 

(1) Trough aluminum insulating glass process and equipment configuration: the glass washing and drying section of insulating glass production line, the glass plate press of insulating glass production line, butyl coating machine, two-component glue machine, molecular sieve filling machine and so on.

The glass washing section of insulating glass production line 1
The plate-press section of insulating glass production line 2
Automatic insulating glass butyl extruder coating machine
Manual two-component sealant glue machine
Automatic insulating glass desiccant filling machine

(2) Basic functions and technical points of each process 

A. Designed according to user requirements includes corresponding and reasonable design according to user's size requirements, specification requirements, structural requirements, quality requirements, and other requirements. Design according to users is the first process and important link in the production process of insulating glass.

B. The basis of the design is mainly the "Insulating Glass" standard, some industry regulations, and empirical data.

C. The main content includes glass size, specification design, aluminum spacers, specification design, sealing material requirements, etc.

D. Glass cutting is to cut the whole piece of glass according to the specific size designed by the user.

In the cutting process, the following technical requirements must be grasped:
an It must be accurate, and the error is within the range specified by the international industry standard "Insulating Glass"; the size of the cutting line must be uniform, and the depth and width of the cutting line must be consistent during the cutting process;

b. The folding mechanism must be reliable. 

When folding, the axis of the folding top rod coincides with the cutting line of the glass to ensure that after the folding, the surface of the glass segment c is perpendicular to the glass plane, and the segment surface is huge, and the flatness should be good, laying a foundation for edging. 

Figure 1 The glass cutting 1

Figure 1 The glass cutting 1

E. Glass edging 

The role of glass edging mainly has two points: 

a. The sharp angle of the glass edge and the sharp edge is dull; 

b. The edge stress of the glass edge is eliminated. 

c. Most glass edging uses soft abrasive belt grinding. Therefore, the abrasive belt has a longer grinding life, but special attention should be paid to grinding from the middle of the glass to the two ends. Do not enter the abrasive belt at one end to avoid the abrasive belt. 

Figure 2 The glass grinding and polishing 1

Figure 2 The glass grinding and polishing 1

F. Glass washing and drying 

Glass washing and drying is important link in the production of insulating glass. The quality of washing and drying determines the quality of insulating glass products, so we must pay great attention to it.

Technical points of glass washing and drying:

a. According to different regions and different water quality, whether to soften the cleaning water.

b. The washing water is generally recycled, so it must have a good filtering function.

c. It is better to have two drying air knives to dry the cleaned glass twice, especially the second air knives use heat to make the dried air have a temperature of about 50 ℃, the purpose is to improve the drying efficiency; It is easy to find residues and crystal points on the glass.

d. During the washing and drying process, the guide rollers, rollers, spacers, etc. in contact with the glass must be resistant to aging and not fade, so as not to affect the quality of the glass.

Figure 3 The glass washing and drying 1

Figure 3 The glass washing and drying 1

G. Blanking of aluminum spacer    

Attention should be paid to 3 steps in the blanking of aluminum spacers:    

a. The size of the blanking must be accurate (usually there is a fixed length on the blanking equipment)    

b. The cut section of the spacer is neat, without burrs, etc.;    

c. Do not damage the original cross-sectional size of the spacer for subsequent use.
H. Filled molecular sieve Filled molecular sieve is an effective means to maintain the dry balance of the hollow glass cavity. 

Main requirements: 

a. Choose a suitable molecular sieve; 

b. The filling process must be fast; 

c. The molecular sieve must be kept dry and the environment must be kept dry; 

d. The filling should not be overfilled, and leave a space of 30-40mm to avoid the Thermal expansion and contraction of the molecular sieve;

 The technical points of aluminum spacer frame assembly: 

a. Keep the surface of aluminum spacer and gusset clean. 

b. Hang and place properly after assembly, and the surface must not be stained.

Figure 4 The insulating glass aluminum spacer frame 1

Figure 4 The insulating glass aluminum spacer frame 1

I. Apply sealing butyl rubber 

Sealing butyl glue is an important part of insulating glass, which determines the overall quality of insulating glass products (whether it meets the five indicators of national standards), and this link must be paid attention to. The technical points: a. Choose suitable quality-guaranteed butyl rubber products; b. Glue must be uniform and the cross section of the glue must be consistent; c. It has good buoyancy and adhesion to glass. d. Good sealing performance

J. Aluminum spacer frame combined sheet 

The technical points of the process of combining aluminum spacer frame and glass: a. The size of each part must be guaranteed, and the shelf frame must not be offset; b. Keep each part clean, especially the inner cavity of the insulating glass.

K. Cold forming 

Cold pressing is an important process of insulating glass. The effect of cold pressing determines the forming size, quality and service life of the product. 

a. The pressure must be uniform, and the pressure rollers must be parallel and synchronized; 

b. The leading and trailing ends of the insulating glass have the functions of holding pressure and boosting pressure, and the positions must be accurate; 

c. Cold pressure can be adjusted 

d. During the cold pressing process, the glass must not be displaced (displaced).

L. Coated sealant 

Coating the sealant is the last process of insulating glass products. The main purpose is to increase the sealing and bonding between the glass. The traditional sealant uses two-component polysulfide glue. Due to environmental protection and cost reasons, it is now available The new sealant-hot melt adhesive has a more ideal overall effect. 

Technical points for two-component polysulfide adhesives:

a. The components of A and B components should meet relevant standards;

b. The mixing ratio of components A and B can be adjusted between -7:1 and 14:1;

c. The components A and B should be mixed thoroughly;

d. It has good curability, tightness and comprehensive performance;

e. Gluing is accurate, no lack of glue and excessive glue.

Technical points for hot melt adhesives:

a. The spacer frame and the glass should be positioned accurately and have the function of pressing and fixing;

b. The glued cross-section is suitable for the requirements (too much will increase the cost, and too little will result in insufficient sealing performance).

Figure 5 The secondary sealant sealing of Insulating glass 1

Figure 5 The secondary sealant sealing of Insulating glass 1

2. The production process, equipment and technical points of composite rubber-strip insulating glass

The process flow and use equipment configuration of composite rubber-striped insulating glass have many differences and overlaps, such as: design, glass cutting, glass cleaning and drying, etc., designed according to user requirements, and trough aluminum hollow glass The same glass, glass cutting and blanking, the same as trough aluminum insulating glass, glass washing and drying, the same as trough aluminum insulating glass, glue strip installation and assembly.

The installation and assembly of the rubber strip is an important part of the composite rubber-strip type insulating glass. The technical points of the installation and integration of the rubber strip are: 

A. To install the rubber strip, a special tool—the rubber strip installer must be used to ensure that the rubber strip is parallel to the glass; 

B. Keep the inner cavity of the glass clean and ensure the quality of the hollow glass; 

C. Leave a small opening in one corner of the rubber strip around it for exhaust when it is hot pressing;

Hot press forming Hot press molding is the last process of composite plastic insulating glass, and its hot press quality directly affects the quality of the product.

The rubber-strip insulating glass must be heated before pressurization. Its purpose is to increase the viscosity of the rubber-strip, increase the firmness of the bonding between the glass and the rubber-strip, and ensure the proper sealing performance.

A. When hot pressing into the glass, leave the mouth side out to facilitate air removal. 

B. The glass is not allowed to be misaligned and must be kept parallel; the temperature of the rubber strip is 37.7~38.8℃ is the most suitable.

Raw material selection and service life of insulating glass

1. The choice of glass 

According to the relevant international industry standards and regulations of Insulating Glass, insulating glass can be made of flat glass, tempered glass, heat-absorbing glass, heat-reflective glass, patterned glass, etc., and float glass should meet the requirements of the relevant international industry standards of Insulating Glass. Grade product, superior product or preferred product. Laminated glass should comply with the relevant international industry standards of "Insulating Glass". Tempered glass should comply with the relevant international industry standards of "Insulating Glass". Other types of glass shall be negotiated between the supplier and the buyer.

The use of ordinary flat glass should be avoided. The transparency and strength of ordinary flat glass cannot meet the requirements. The above-mentioned glass must meet the requirements of the corresponding standards and can be used after passing the inspection.

For different batches of glass from different manufacturers, the color difference should be checked before cutting, and the glass with larger color difference should be used in different projects or different building facades.

The size of the glass should be strictly implemented in accordance with the requirements of the drawings. At the same time, the operator should pay attention to the good protection of the glass surface, and there should be no obvious defects such as scratches or bubbles.

Commonly used insulating glass shape and maximum size table

Original glass thicknessAir layer thicknessSquare sizeRectangle size

The allowable deviation table of the length and width of the insulating glass

LengthAllowable deviation

Insulating glass thickness tolerance table

Glass thicknessNominal thicknessAllowable deviation

Permissible deviation table of two diagonals of insulating glass

Diagonal lengthDeviation

2. Sealant selection    

The performance of insulating glass includes sealing performance and structural performance. Understanding the structure type of insulating glass is of great significance to the correct selection of insulating glass sealant, the correct manufacturing method and quality control.

The hollow glass structure refers to the combination of sealant and spacer frame.

(1) Structure of insulating glass 

A. Single channel seal The hollow glass structure has only one glue layer and does include

a, polysulfide glue; 

b, hot melt butyl glue (Hot melt sealant); 

c, polyurethane; 

d, swiggle spacer bar 

B. Double seal Two-layer glue for insulating glass structure includes: 

a. The first glue is polyisobutylene (PIB); 

b. The second glue includes polysulfide glue, polyurethane and silicone glue.

It is especially emphasized that for structural installation of insulating glass (insulating glass for curtain walls), the sealing system must have extremely high adhesion and anti-ultraviolet ability, so it must be sealed with polyisobutylene (PIB) and silicone rubber.

(2) Types of insulating glass sealant 

A. Thermoplastic sealant includes a hot melt butyl rubber (Hot melt sealant) 

B. Swiggle tape

c. Polyisobutylene (PIB) 

B. Thermosetting sealants include: 

a, polysulfide glue; 

b, polyurethane; 

c, silicone glue 

(3) Performance and comparison of insulating glass sealant

Sealing materialResistance to water vapor transmissionWater vapor transmission rateGas holding capacityRelative value of argon retention capacityUV resistanceHigh temperature performance

Hot melt butyl rubberExcellent0.65Good~Excellent2GoodGood




Silicone glueBad≥200Bad665ExcellentGenerally

Swiggle tape spacer barExcellent0.65Good~Excellent2GoodGood

(4) Comparison of different sealing processes for insulating glass

ProjectOne-component hot melt adhesive processTwo-component glue processComfortable rubber strip process
ProductivityHigh (the annual production capacity of a single shift reaches 80,000)LowerHigh
Process complexityFew procedures, relatively simpleMany and complicated processesThe easiest
LaborFew staffMany staffMinimum staff
Production environment requirementsNo special requirementsHigh requirements, longer curing time at low temperatureNo special requirements
Curing time2~3min24hWithin 10min
Equipment maintenanceSimple and highly reliableHarderSimple and highly reliable
Scope of applicationSuitable for insulating glass for doors and windowsSuitable for all insulating glassdOnly applicable to insulating glass for doors and windows

From the above comparison, it is not difficult to see that each process has its own characteristics, and which process to use depends on considerations such as quality, production efficiency, and cost. The products produced must not only meet the requirements but also be of good quality and low price, in order to occupy the market.

For more information about Jinan LIJIANG Glass insulating glass processing equipment and insulating glass processing accessories, please click here to learn more. 

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