UV BONDING - Logli Massimo

glass system technology
UV BONDING
UV BONDING
INTRODUCTION:
In the recent past UV bonding technology has become more and more common thanks to its undisputed
advantages: the extreme versatility of use, as it allows the joining of materials with different shapes
sometimes also complex and short execution times with the relative reduction of production costs.
The information contained in this manual are the result of our technical and practical experience
gained over the years working in the field of industrial and artistic glass.
Nevertheless each application must be carefully evaluated in all its details and never underestimated.
We invite you to contact our technical service to expose your application needs.
It will be our pleasure to offer you our technical consultation.
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INTRODUCTION TO BONDING
The bonding is the operation to permanently adhere the two surfaces of the same material, or even
of different materials, using adhesive. The adhesive is defined as:
"Non-metallic substance capable of joining materials by surface attachment chemistr y (adhesion),
so that the bond obtained possesses adequate internal strength (cohesion)”.
The adhesion is the ensemble of molecular bonds that are created between material and adhesive placed in
contact. The cohesion is the inherent strength of a material. These molecular bonds between the adhesive
and the surface as well as involve the area of contact between these (area of adhesion), involving also the
adhesive layer near to the surface (transition zone).
• In the area of cohesion, which is the innermost part of the adhesive, the latter is present in its
normal state and has the nominal properties reported in the data sheet.
• In areas of adhesion and transition, represented by adhesive layers closer to the surface,
the structure, composition and properties of the adhesive will be different.
BONDING EFFECTS THREE DIFFERENT AREAS
MATERIAL 1
BOND AREA
TRANSITION AREA
ADHESIVE
COHESION AREA
TRANSITION AREA
BOND AREA
MATERIAL 2
The quality and duration of a bonding are strongly linked to its moisture resistance.
The properties of an adhesive are guaranteed by the manufacturer.
Users should reach them through the application and curing of the adhesive in a workmanlike manner.
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WETTABILITY:
NECESSARY CONDITION FOR BONDING
A necessary condition but not sufficient to form a good bond is given by the adhesive capacity to wet
the surface to be bonded (wettability of the adhesive).
If the surface and the adhesive are incompatible, for example because the adhesive has poor wettability
or because ties that are generated are too weak, you can use an adhesion promoter.
Aspects that influence the wettability.
• Flatness is the surface’s condition where all it’s points belong to the same plane.
The better is the surface’s flatness the more effective the bonding will be.
Smooth surfaces require adhesives generally liquids, viscous adhesives irregular ones.
• Roughness of a surface is composed of micro-geometrical imperfections inherent or resulting
from machining. Surface irregularities cause various mechanic resistances, reducing the final
resistance N / mm ².
• Porosity of a material is a scalar quantity defined by the ratio between the volume of voids in it
content and its total volume. The capacity of a material to absorb the adhesive, before hardening,
determines the amount of adhesive to be used. If an adhesive is too fluid it will be absorbed by the
material before hardening with an unsatisfactory bonding result. The more porous a material is,
the more dense the adhesive must be.
• Viscosity is a magnitude which quantifies the resistance of fluids to flow. It is expressed in Pa.s or
in mPa.s. The viscosity of the adhesive must be adapted to the application method that is adopted
and to different surface flatness.
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SURFACE TREATMENTS TO IMPROVE THE BONDING
To improve the effectiveness of the bonding is possible to subject the surface to different treatments.
We distinguish three types of "surface treatments":
SURFACE
PREPARATION
FIRST SURFACE
TREATMENT
SECOND SURFACE
TREATMENT
Cleaning, degreasing
(using our Products VITRASOL
or VITRASOL BLU)
Mechanical, chemical,
physical technics
(using our product PIROGLASS)
Acclimation, primer, activators
(working environment must have
humidity ˂ 40%, temperature
within 12°C and 35°C)
TYPE OF RESISTANCE REQUIRED
The adhesive selection must be
based on the type of constant (for
as a weight) or variable in time
(for example of vibrations) stress
the components will be subjected
to possible stresses:
3) Cleavage forces actes in the direction of
leverage on the edge bonding.
1) Traction forces, perpendicular to the
surfaces, tend to separate them.
2) Cutting forces tend to slip one on the glued
surfaces.
4) Peeling forces remain on the edge bonding
and on the flexible surface.
5) Compression forces push the two surfaces
towards each other.
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UV GLUE:
ADHESIVES THAT HARDEN BY CHEMICAL PROCESS
FOR RESULT OF EXPOSURE TO UV RADIATION
The necessary condition to use UV adhesive is that at least one of the materials is transparent
to UV rays , otherwise polymerization will not take place.
These adhesives are one-component systems to polymerize and harden as a result have need of a radiation
(ex.: light, electron-beam, UV) with a certain wavelength ( from 365 nm at 405 nm ) and a certain
intensity (minimum intensity for the activation of 60 mW / cm ²).
UV adhesive do not require kiln, nor solvents and the process is quite short
(from few seconds to few minutes).
These adhesives can reach a cutting resistance up to 28 N / mm² about. The bonding obtained may be
exposed to temperatures ranging from -30° C up to max. 140 ° C and for short periods also at higher
temperatures, different according to the adhesive.
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ADVANTAGES OF UV ADHESIVES:
1)
2)
3)
4)
5)
6)
Ease use.
Controlled Polymerization.
Excellent adhesion persistent even at high temperatures of the materials bonded.
Transparency.
Allows the adhesion between different materials such as metals, glass, wood, plastic, marble.
Speed fastening with consequent production increase and reduction cost.
Tests over LAMP002
Average values of radiation intensity noticed in function of lamp’s distance
Lamp
LAMP002
(250 Watt)
UV meter distance
from lamp [cm]
Radiation’s intensities
average values
[mw/cm²]
Radiation’s intensity values
[mW/cm²]
0
138
139
140
139
5
99
100
101
100
10
76
74
78
76
15
60
62
62
61
20
45
46
42
44
Tests over LAMP003
Average values of radiation intensity noticed in function of lamp’s distance
Lamp
LAMP002
(500 Watt)
UV meter distance
from lamp [cm]
Radiation’s intensities
average values
[mw/cm²]
Radiation’s intensity values
[mW/cm²]
0
174
174
173
173
5
144
142
141
142
10
102
106
106
105
15
74
76
76
75
20
55
55
54
55
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PERFORM A BONDING UV
1) Be sure to perform the bonding in an environment having a temperature between 12 ° C and 35 ° C
and humidity 40% lower.
2) Choose the adhesive according to the materials to be bonded, the efforts that will be submitted
and the environment final (humidity and temperature) with the help of the table in the catalog.
3) Clean, for the first time, the surfaces to be
bonded with VITRASOLV or VITRASOLV BLUE
using cloth (we recommend a woven non-woven
cloth. Do not use paper) for eliminate most of
the dirt and contamination. (*)
4) Perform the flame with PIROGLASS: pass the flame for 5 sec. at a distance of 5-6 cm from the surfaces
to be bonded and remove moisture that occurs as a condensation with a cloth tnt. It increases by 30%
the effectiveness of bonding. (**)
5) Clean, a second time, the surfaces to be paste
with VITRASOLV or VITRASOLV BLUE with aid
of a cloth, to eliminate any dirt and residue
contamination.
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IF THE ADHESIVE HAS LOW VISCOSITY (follow steps 6A and 7A):
6A) Place the pieces that you want to permanently bonding with the aid of the supports and suckers.
7A) Apply the adhesive from side leaving it act for capillarity.
IF THE ADHESIVE HAS HIGH OR MEDIUM VISCOSITY (follow steps 6B and 7B):
6B) Apply the adhesive prior to placement of the parts.
7B) Place the pieces that you want to permanently bonding with the help of the supports and suckers.
8)
Activate the applied adhesive with one of our UV lamps ( which cover the wavelength and intensity
of radiation corrected for the activation of the adhesives ), keeping the lamp at a distance of 5 cm.
from adhesive for 5-6 sec. (***)
9)
Remove the supports
10) Clean the glass with VITRASOLV to remove any UV adhesive excess not yet hardened.
11) Finish catalyze the UV adhesive with UV Lamp for 50-60 sec. (***)
(*)
It is recommended to check the flatness of the surfaces to be bonded to make the most effective and economical bonding.
(**)
It is recommended to perform the bonding in environments with humidity not exceeding 40% and at temperatures between 12 ° C and 35 ° C,
in order to reduce the humidity conditioning of the environment where it operates.
(***) If the size of the part to be bonded is larger than the size of the lamp, move the lamp slowly along the surface back and forth so that the
total time of irradiation of each portion is the one required. Do not keep the lamp in a position for the required time and then move to the
next position, this gives rise to a bad local bonding.
Personal protection
During the bonding must use gloves to protect themselves from contact with the adhesive and at the moment
the use of the UV lamp must use proper eye protection.
The use of good products is a necessary condition, but not sufficient for successful bonding. Much of its
success depends by the operator. In this regard, it is recommended that to follow training courses by
operators who perform the bonding.
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