Preparation of coil coatings resistant to high temperature heat transfer

Preparation of high temperature heat transfer coil coatings
Tian Yongfeng, Li Jianfei, Ding Yuanwen, Xu Runbin
(Zhongyu North Coatings Industry Research and Design Institute Co., Ltd., Lanzhou 730020)

first screened several different types of silicone resins, then 1053 as the base resin, titanium white powder as a filler, KH-550 as a curing agent, prepared a high temperature heat transfer coil coating. This paper mainly investigates the effect of yan-based ratio and curing agent dosage on the mechanical and temperature-resistant properties of coating, and improves the surface pressure of coating film by introducing polar resins - 800
-
polyester, and solves the problem that pure silicone resin cannot be thermally transferred because the surface pressure is too low. The test results show that the comprehensive performance of coating film iswhen the amount of polyester is 1.5, 800
and
polyester is 2% of the total amount of resin and the addition of the curing agent KH-550 is 2% of the total paint volume.
keywords:
yan base ratio; high temperature resistance; thermal transfer; coil coating 0 introduction
thermal transfer coating is a special type of coating for heat transfer technology film coating. On the surface of the thermal transfer coating, various patterns can be printed to the coating surface by thermal transfer technology, thus forming a variety of appearance effects on the substrate, which is mainly used in ceramic, glass, aluminum, metal materials and other surface decoration. Coil coating is able to be applied to the surface of the coil by roller coating method, with beautiful appearance, uniform coating, easy processing and molding, high utilization rate of coating advantages. Thermal transfer coil coating is mainly used in polyester film, polyimide film and other non-metallic packaging materials, coated coils are mainly exported to Brazil, India and Malaysia and other countries.
paper mainly for polyimide film coil preparation of a short-term high temperature resistance of white thermal transfer coil coating. Therefore, the prepared coating must have a thermal transfer function at the same time, but also can be applied to the polyimide film coil roller coating requirements.
1 Test Part
1.1 Test raw materials and instruments
the main raw material specifications and instrument and equipment models for testing are in Table 1.
1 Main raw materials and equipment
name
special model
manufacturer
methyl MQ silicone resin
industrial grade
Shanghai Ai Expo Silicone Materials Co., Ltd.
105 3
Industrial
Zhongyu Chenguang Chemical Research Institute Co., Ltd.
9803
Industrial Grade
Changzhou Cano Silicone Co., Ltd.
9801
Industrial Grade
Chang Gano Silicone Co., Ltd.
KH-550
Industrial Grade
Nanjing Lipai Chemical Co., Ltd.
800
Industrial Grade
DSman
Titanium White Powder R -215
Industrial Class
China Nuclear Huayuan
Rapid Dispersion Tester
KS-370
Shanghai Modern Environmental Engineering Technology Co., Ltd.
electric thermostat constant wind drying box
101-3A
Jiangsu Tongjun Instrument Technology Co., Ltd.
program-controlled Mafu Furnace
CQ-C40
Luoyang Pure Green Furnace Industry Co., Ltd. 1.2 Test Process Flow
Test Process Flow As shown in Figure 1.
Figure 1 Process
Process Description: Weighing resins, solvents and additives into a quick-hand bottle, hand shake and smoothly add fillers and glass beads, disperse using a fast dispersion test machine< Then, a certain amount of lacquer liquid and curing agent are applied, and the appropriate amount of solvent is added to adjust to the construction viscosity;
1.
3 performance testing methods and requirements
1.
T-bend test
3.1 T-bending coating is carried out in accordance with the GB/T 30791-2014 medium-color paint T-bend test method.
1.
3.2 Adhesion
600 models of 3M tape completely covered on the coating film, paste flat, and then tear off the tape hard. The coating film is required to be intact and will not fall off the polyimide film.
1.
3.3 Surface
the coating surface stress is tested using the blue-purple Dain pen (surface stress test pen) of the ACCU of the United States. The surface stress test method of the coating film is: first estimate a value, using the corresponding value of the Dain pen coating and coating on top of the film, if the liquid in the dain pen can be evenly spread and coating on top of the film and no contraction phenomenon (time is generally 2 to 3 s), you need to select a larger value of the Danin pen to continue the test; If the liquid in the Dain pen shrinks on the surface of the coating film, it is necessary to select a smaller value of the Dain pen to continue the test, until the liquid of the Dain pen is just able to wet the coating surface, the corresponding Danin pen value is the surface pressure of the film under test, in dyn/cm.
1.
3.4 temperature resistance
coating film on the steel plate, 180 degrees C×5 min solidified completely after baking 2 h in a constant temperature oven at 400 degrees C, to be naturally reduced to room temperature, with the naked eye to see if there is a significant color difference.
2
results and discussion
2
.1 resin selection
due to the high heat resistance requirements of the coating, the coating film needs to be 400 degrees C×2 h without the naked eye Visible color changes, ordinary organic resins are difficult to meet the requirements of this indicator, and silicone resins are highly cross-networked structure of polysilicon oxane, good temperature resistance, both organic resins and inorganic materials with dual properties, with unique physical and chemical properties. Therefore, the resins used for screening are all silicone resins or modified silicone resin products. There are many types of silicone resins, according to their types mainly include methyl silicone resin, methyl benzene silicone resin, methyl MQ silicone resin, vinyl MQ silicone resin, silicone resin emulsion, epoxy modified silicone resin, silicone polyester modified resin, acrylic modified silicone resin and so on. In this paper, the following silicone resins are mainly tested and compared, as detailed in Table 2.
2 Effects of different resins on coating performance
Coating performance
resins
methyl MQ silicone
1053
9803
9801
thicknesses m
12
12
12
12
Adhesion
Tape can't be pulled off
Tape can't be pulled off
Tape can't be pulled
Tape can't be pulled off Dropped
T bend
0T
0T
0T
0T
surface stress / (dyn.cm
-1
)
<36
<3 6
<36
<36
Temperature resistance (400 degrees C×2 h)
yellowing, cracking
slightly yellowing
turning brown
turning brown
As can be seen from Table 2, the selected resins are flexible and adhesive on polyimide films, and the surface pressure is lower than 36 dyn/cm× Chromication; fracking may be related to its molecular structure, methyl MQ silicone resin is a three-dimensional (nonlinear) structure of the molecule with Si-O bonds as the skeleton of the silicone polymer material, cured into a film itself high crosslink density, coupled with 400 degrees C conditions, part of the methyl group began to break down the cohesion reduced resulting in cracking. 1053 resin is methyl benzene silicone resin, is composed of methyl chlorosilane, benzoyl chlorosilane monomer hydrolysalized, reduced into a polymericilsoxyane branch chain prepolymer, polymerized formed by high body size Molecular polymer; the benzene-based group in the resin improves the temperature resistance of the resin, making the anti-yellowing ability slightly better than that of methyl MQ silicone resin; 9803 and 9801 are epoxy modified silicone resins and acrylic modified silicone resins, their temperature resistance is not good, 400 degrees C×2 h then brown; Therefore, taking into account, 1053 is chosen as the base resin.
the
of the 2
.2 pigmentation filler will reduce the cohesion of the coating film, thus affecting other properties of the coating film. After selecting silicone tree, the effect of the pigment ratio on film adhesion, flexibility, surface strain and temperature resistance was examined by using titanium white powder as a filler, and finally determined the optimal pigment ratio, as detailed in Table
3.
3 Effect of Yanjibi on coating performance
Coating performance
Yanjibi
1.0
1.2
1.5
1.7
2.0
thickness/sm
12
12
12
12
12
Adhesion
tape can't be pulled off
tape can't be pulled off
tape can't be pulled off
tape can be pulled off
tape pulls off
T Bend
1T
1T
2T
3T
4T
Surface Stress/ (dyn.cm
-1
)

<36
<36
36
38
40
temperature resistance (400 degrees C×2 h)
slight yellowing
slight yellowing
no significant change
A significant change
no significant change
as can be seen from Table
3: changes in the face ratio have a significant impact on the flexibility, adhesion, surface strain and temperature resistance of the
coating film.
with the improvement of the face ratio, the adhesion and flexibility of the coating film are worse, the surface tension is improved, and the temperature resistance is better. The main reason for the increase of surface tension may be that with the increase of pigment ratio, the relative decrease of resin makes the filler not completely covered, the coating surface shows the nature of part of the filler surface,
and the filler surface contains more polar groups such as hydroxyl, which makes the surface tension of the coating film increase. Taken together, the paint selection has a face-to-face ratio of
1.5.
2
.3 curing agent dosage
1053 silicone resin usually uses KH-550 as a curing agent, the curing principle is shown in Figure 2.
Figure
2
Coating film curing signal fect as shown in Figure
2
, the curing mechanism is mainly in the resin
-OH and triple-energy silane couplings
of the alkyl de-alcohol reaction and resin hydroxyl de-curing reaction, forming a spatial network structure and cross-curing into a film. In this paper, the effect of the amount of curing agent on the main performance of coating film is examined by experiment, as detailed in table
4.
4 Effect of curing agent dosage on coating performance
Coating performance
KH-550 addition (mass percentage of total paint)
1
2
3
thickness/sm

12
12
12
Adhesion
tape can't be pulled off
tape can't be pulled off
tape can't be pulled off
curing degree (180 degrees C×5 min)
not fully cured
fully cured
fully cured
T bend
2T
2T
2T
surface stress / (dyn.cm
-1
-1

)
36
36
36
As can be seen from Table 4, the addition of KH-550 curing agent does not exceed 3%, there is no significant effect on the adhesion, flexibility and surface strain of the coating film. When its dosing is 1% of the total paint volume, the coating film can not be completely cured, the film coated with the film folding, and then by hand pinch can hear the sound of the coating film adhesion≥ Therefore, this paper selects the curing agent dosage as the minimum amount that can make the coating film completely cured, that is, 2% of the total paint volume.
2
.4 Effect of polar resin on
coating
performance When the yanji ratio is determined to
1.5:1.0


, the surface strength of the coating film does not reach the requirements of
40 dyn/cm;