In this study, to synthesize the core-shell (PS-PBA) copolymer latex core particles, the materials which are used in the synthesis, blending and coating, the manufacturers, the purity and all the instruments for analyses are listed in Table 3-1 and in Table 3-2, respectively.
3.1 Materials and instruments
Table 3-1 Materials
No. name manufacturers purity
1 Styrene Acros 99%
2 Butyl acrylate Acros 99%
3 Potassium persulfate Sigma ACS,≥99.0%
4 Triethoxyvinylsilane Acros 97%
5 1H,1H,2H,2H-Perfluorooctyltriethoxysilane flurochem 95%
6 Trimethoxy(octadecyl)silane Sigma 90%
7 (OTS)Trimethoxy(octyl)silane flurochem 96%
8 Ammonium hydroxide solution Sigma ACS,28-30%
9 Etersol 1135-9 Eternal Material 48%
10 Dipropylene glycol n-butyl ether(DPnB) Dow Chemical >99%
2 Heating magnetic stirrer EYELA N-1000V
3 PH meter JASCO FP-6300
4 Centrifuge Perkin-Elmer PYRIS
5 Scanning Electron Microscope JEOL JSM 6700F
6 Wire Wound Coating Rod R.D.Specialties 1/4” X 16”
7 NOVO-GLOSS 60o gloss meter RHOPOINT
INSTRUMENTS
Single 60o version
3-2 Synthetic method
The gloss matting core-shell (PS-PBA) copolymer latex particles were synthesized via the following steps
3-2-1 Synthesis of the core-shell (PS-PBA) copolymer latex core particles
The (PS-PBA) copolymer latex is synthesized via soapless emulsion polymerization and the experiment procedures are described as follows:
The soapless emulsion polymerization is carried out in a four-neck flash reactor equipped with a thermometer, nitrogen inlet, agitator, and a water-cooled reflux condenser. First, styrene, butyl acrylate and DI water were added into the reactor. The reaction mixture is degassed using nitrogen under vigoruous agitation. The temperature is then raised and the polymerization was performed for a while until the (PS-PBA) copolymer latex with 60-70% of conversion.The reaction scheme for the synthesis of core-shell (PS-PBA) copolymer latex core particles is shown in figure 3-1.
Figure 3-1 Reaction scheme for the synthesis of core-shell latex core particles.
Styrene
Butyl Acrylate
Soapless Polymerization
(PS-PBA) copolymer Core
PS-PBA
3-2-2 Swelling of the core-shell (PS-PBA) copolymer latex core particles
Take the gloss matting latex particles whose formulation is D1 as an example. The (PS-PBA) copolymer latex was swollen with the addition vinyl-silane and styrene dissolved in methanol for a while at room temperature.
3-2-3 Copolymerization of (PS-PBA) copolymer latex
The reaction mixture is degassed using nitrogen min under vigorous agitation. The temperature is then elevated to high temperature for restarting the polymerization of the copolymer. The soapless emulsion polymerization was allowed to proceed at high temperature to obtain the (PS-PBA) latex core enclosed by SIOH or SIO2 groups which act as the shell of the latex. The reaction scheme for the swelling and copolymerization of (PS-PBA) copolymer latex core particles is shown in figure 3-2.
Figure 3-2 Reaction scheme for the swelling and copolymerization of (PS-PBA)
3-2-4 Sol-gel reaction of core-shell (PS-PBA) copolymer latex particles
The (PS-PBA) copolymer latex is cooled to room temperature after the polymerization.
Silane with F or long carbon chain functional groups is dissolved in methanol and added into the (PS-PBA) copolymer latex to undergo the sol-gel reaction. The sol-gel reaction is carried out at room temperature for while to obtain the final product: Core shell (PS-PBA) copolymer latex particles
Silane with F functional groups is dissolved in methanol to undergo the sol-gel reaction at room temperature for a while. The latex particles can be used as the gloss matting latex particles.
The reaction scheme for the synthesis of the core shell (PS-PBA) copolymer latex particles is shown as Figure 3-1. The synthesis of the core shell (PS-PBA) copolymer latex particles bonded with F atoms is taken as an example.
Figure 3-3 Reaction scheme for the sol gel reaction of core-shell (PS-PBA) copolymer
latex particles.
3-3 Blending method
The blending of the glossy paint Etersol 1135-9 with the gloss matting agent includes many steps, and I take the Formulation: D1 3.5% + OTS-(PS-PBA) 15% as an example to illustrate how to blend the gloss matting agent with the glossy paint Etersol 1135-9
1. Pour 50g glossy paint Etersol 1135-9 into a 250ml beaker. Afterward, stir the glossy paint Etersol 1135-9 for about 3 min under 1000rpm agitation speed in a 40-45oC water bath and make sure the water bath is kept at 40-45 oC
2. Dilute the OTS-(PS-PBA) copolymer which goes through repeated centrifugation with 1wt% surfactant of the glossy paint Etersol 1135-9 water solution to make the solid content of the solution remain 20%
※ The amount of the OTS-(PS-PBA) copolymer the blending takes can be calculated by
the following formula:
Amount of the PBA) copolymer=50․15%/ the solid content of the
OTS-(PS-PBA) copolymer
3. Add the diluted OTS-(PS-PBA) copolymer mixture into the glossy paint Etersol 1135-9 with a speed of 2-3g OTS-(PS-PBA) copolymer mixture per minute under 1000rpm agitation speed. After the addition of all the OTS-(PS-PBA) copolymer, make sure the mixture mixes well with the glossy paint Etersol 1135-9 and the temperature is kept at 40-45 oC
4. Add D1 into the mixture mentioned above with a speed of 2-3g D1 per minute under 1000rpm agitation speed. After the addition of D1, make sure D1 mixes well with the mixture mentioned above and the temperature is kept at 40-45 oC
5. Remove the mixture in the 250ml beaker from the water bath. Keep stirring the mixture under 1000rpm agitation speed for 30 minute to obtain the product. Pour the product into a 50ml glassy bottles and turn the caps closed and wait for 1 day to defoam to obtain the product.
Note: D1 refers to
2% wt% surfactant of the glossy paint Etersol 1135-9 water solution(aq)： DPnB = 1:1
3-4 Coating method
1. Attach the glass substrate to a flat hard surface
2. Apply some drops of gloss matting paint at the top of the substrate
3. Drag the wire wound coating rod down the glass substrate with even pressure and speed and keep the rod from rolling to form an uniform liquid film on the glass substrate
4. Take the glass substrate into a 50 oC oven right after the completion of the coating 5. Dried the liquid film for 3 days to remove all the DPnB in the film
3-5 60
ogloss measurement
1. place the 60o gloss meter on the top of the glass substrate coated with glareless paint
2. measure the 60o gloss of the surface using the 60o gloss meter throughout the whole surface and take the average and standard deviation from all the measuring data
3-6 Film property tests
3-6-1 Water resistance test
1. Lay a 2cm x 2cm filter paper on the surface of the glass substrate coated with the glossless paint. Then, put some cotton on the filter paper.
2. Apply some drops of DI water onto the filter paper in a closed system to keep the water from evaporating.
3.Wait for 24hr to observe the change of the film
※Test standard: There should be no change to the film, including no sign of whitening,
shining, softening.
3-6-2 Alcohol resistance test
1. Lay a 2cm x 2cm filter paper on the surface of the glass substrate coated with the glossless paint. Then, put some cotton on the filter paper.
2.Apply some drops of 48-50 wt% Ethylene Alcohol water solution onto the filter paper in a closed system to keep the solution from evaporating.
3.Wait for 1hr to observe the change of the film
※Test standard: There should be no change to the film, including no sign of whitening,
shining, softening.
3-6-3 Boiling water resistance test
1. Lay a glassy cup with boiling water slightly overflowing on the surface of the glass substrate coated with the glossless paint.
2.Wait for 1hr and remove the glassy cup to observe the change of the film
※Test standard: There should be no change to the film, including no sign of whitening,
shining, softening.
3-6-4 Scratch resistance test
1. Remove approximately 5 to 6 mm of wood from the point of a wood pencils using pencil sharpener. Then, Hold the pencil at an angle of 90° to the abrasive paper and rub the lead against the paper for a flat, smooth and circular cross section is obtained.
2.Place the coated glass substrate, on a firm, horizontal surface. Starting with the hardest pencil, hold the pencil firmly with the lead against the film at a 45° angle and push away from the operator with uniform and sufficient pressure downward and forward.
3 Repeat the process down the hardness scale until a pencil is found that will not cut through the film to the substrate for a distance of at least 3 mm
3-7 SEM sample preparation
1. To mimic the real film on the glass or wood substrates, we some drops of gloss matting paint which goes through the process of blending are dipped onto the aluminum foil for a complete film on the foil.
2. The foil is heated in the oven under 50oC for 3 days for complete film formation.
3. A part of film is cut and goes through brittle fracture in the liquid nitrogen.
4. The film is stick to the sample holder for analysis of the cross section.
5. The sample is analyzed by the SEM.