Synthesis and Characterization of PolyacrylateBinding Substance Modified by Polyurethane Sudip K. Lahiri 1, 2, a, R. Amin 1, 2, b, Aman-Ullah Ghazi 1, 2,c,, Heng Quan 1, d 1
Wuhan Textile University, School of Chemistry and Chemical Engineering, Wuhan, 430073, China 2 Workstation of Wuhan Textile university (Zhejiang Runhe Chemicals new materials Co., Ltd) graduate student, Zhejiang, China a
[email protected],
[email protected],
[email protected],
[email protected] Corresponding author: H. Quan; E-mail:
[email protected]
ABSTRACT: In this research paper, polyeather diol (N220) / polyester diol (3030), isophorone diisocyanate (IPDI), 1, 4-butanediol (BDO) as a polymer chain extender, dimethylolpropionic acid (DMPA) and capping agent hydroxyethyl methacrylate (HEMA) were used to preparewaterborne polyurethane. And then polyacrylate emulsion was prepared with the presence ofmonomers as butyl acrylate (BA), acrylic acid (AA), n-methyloacrylamide (N-MM), styrene (ST) and methyl methacrylate (MMA)in which polyacrylate was adopted to modify polyurethane and some catalysers, emulsifier were added including fatty alcohol-polyoxyethylene ether (AEO9), sodium dodecyl sulphate (K-12) and ammonium per sulfate (APS). The percentage of solid content, dry and wet rubbing fastness on textile, stain resistance, water resistance, emulsion stability, handling properties, elasticity and softness of PUA film, resistance to acid and alkali, viscosity, particle size distribution, as well as dilution stability were studied. Keywords:Polyurethane-Acrylate; Emulsion;Synthesis; Chain extender; Characterization.
1 INTRODUCTION Polyurethane-acrylate (PUA) dispersion, with its advantages of better elasticity and smoothness properties, pigment affinity, cost-effectiveness, more stability, non-sticky and softer over PU emulsion, has been a significant research focus [1-2]. There have been increasing interests in the coating and adhesive applications of aqueous polyurethane dispersions due to their environmental advantages, excellent performances and wide application fields [3-5]. Compared with solvent based products, polyurethane emulsion and polyacrylate emulsion are incombustible, in noxious, environmentally benign, safe and cheap. But, to some extent, they have some disadvantages. For example, PU is of disadvantages in stability, solid content and application range and PA is sticky, poor in abrasion, chemical and water resistances, etc. Because of complementation of PU and PA in property, some researchers proposed a kind of polyurethane-acrylate (PUA) hybrid emulsion which possesses the advantages of both PU and PA. It can potentially combine the high abrasion resistance, toughness and tear strength, as well as the good lowtemperature property of polyurethane and the good optical property and weather ability of polyacrylate [68]. This study was designed to enhance the elasticity, softness, handling properties and non-stickiness of PUA by adding functional polyols and some external chain linking agents such as DMPA, BDO and functional monomers such as BA, AA & ST so as to improve its handling properties and hydrophilicity. Then the prepared PUA emulsion can be used as the printing binder & film-forming resin in coatings and adhesive.
2 EXPERIMENTAL 2.1 Reagents Chemical Pure: 1, 4-butanediol (BDO),dimethylolpropionic acid (DMPA),hydroxyethyl methacrylate
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(HEMA),butyl acrylate (BA),acrylic acid (AA),n-methyloacrylamide (N-MM), styrene (ST), methyl methacrylate (MMA),sodium dodecyl sulphate (K-12), ammonium per sulfate (APS). Industrial Pure: polyeather diol (N220), isophorone diisocyanate (IPDI) and fatty alcohol polyoxyethylene ether (AEO9). 2.2 Experimental Process Preparation of PUA emulsion
COOH
R1
CH3
OCN
R3
CH
H 2C
R6
CH3
R5
CH2
C
R4
HO
C
CH3
CH2CH2CH2
O
O C
O
CH2CH2
CH
OH
R8
O
R7
H2C
CH
CH2CH2CH2CH2 OH
CH3
CH3
H3C
CH2OH
C
HOCH2
NCO
C
R2
O
HO
CH2CH2O
n
CH2CH2CH2O
H m
OH
R8
R7
R5
R3
R1
R2
R1
2.3 Characterization Conversion ratio G% = {(G1-G0W) / (G0M×Solid content)} ×100 In which, G1— Constant dry weight of the sample; G0 — Sample weight; W—{(APS + Emulsifier) / (APS + Emulsifier + Monomers)}; M—{Monomers / (APS + Emulsifier + Monomers)}
Yellow resistance
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R5
n
R6
m
CH2
Dipped and padded the fabric with the solution of 25g emulsion and 25g water, dried it at 100˚C and then set it at 180˚C for 3 min. Measured and calculated the yellowing resistance of that fabric by data color analyzer.
Gel ratio G.R. % = (D1 / D2) × 100 In which, D1—Dry weight of total residue; D2—Total weight of monomer. Particle size and particle size distribution The particle size and its distribution of the obtained dispersion were measured by laser particle size analyzer. Dilution stability The emulsion was diluted to a solid content of 3%, then the emulsion was poured into 30ml tubes after dilution, the liquid column height of 20cm, is placed 72h, measuring the volume of supernatant and precipitate upper portion. Acid and Alkali stability In two test tubes were charged emulsion 5g sample tested, the two tubes were then added drop wise 1ml (1mol / L) hydrochloric acid and 1ml (1mol / L) solution of KOH. After shaking, the PH tested and observed the emulsion is stable. Then the two tubes placed at room temperature for 24h, and then observed the stability of the emulsion. Electrolyte resistance stability Added 16ml polymer emulsion sample into the test tube, then added 4ml of 0.5% CaCl2 solution, shacked and kept for 48h and observed the emulsion changes.
3 RESULTS AND DISCUSSION 3.1 Structural pattern of PUA emulsion Introduced soft, hard acrylate monomers, hydrophilic monomer, chain extender monomer into polyurethane chain that gave the PUA with better elasticity, smoothness & non stickiness(Tab.1), at the same time cap polyurethane macromolecules oligomer with coupling agent,radical initiator used as to increase the reactivity of the end polymer chain to introduce acrylate monomers.
Specimens Soft monomers Hard monomers Hydrophilic monomers Anionic coupling agent Non-anionic chain extender Polyurethane emulsion
PUA-1 (%) 25 3 0.8 5 4 2
PUA-2 (%) 25 3 0.8 5 4 4
PUA-3 (%) 25 3 0.8 5 4 7
PUA-4 (%) 25 3 0.8 5 4 11
PUA-5 (%) 25 3 0.8 5 4 15
Tab.1 Structural characteristics of PUA emulsion 3.2 Conversion ratio of the PUA emulsion
Fig.1 shows the conversion ratio percentages of the polymer for different ratio of polyurethane emulsion to the PUA emulsion. It indicated that, with the increase of polyurethane to the polyacrylate emulsion the conversion ratio increased gradually up to 97% when the PU was 11% and after that - 57 -
when the PU% increased more the conversion ratio decreased to 94%.The conversion rate in polymerization of polymer should be more than 90%.So, they were all up to standard. But in that synthesis process if we kept the polyurethane percentage to polyacrylate as 11% this will be the best conversion ratio. This could be due to that, the increasing of polyurethane most of the pre polymer PU reacts with polyacrylate chain.
conversion ratio %
Fig.1 Polyurethane emulsion % vs conversion ratio % 100 95 90 0
2
4
6
8
10
polyurethane percentage
12
14
16
3.3 Various types of stabilities of the sample emulsion
Auxiliary Dilution Number Stability PUA-1 PUA-2 PUA-3
Stable
Electrolyte Resistance
No Change
PUA-4 PUA-5
Acid and Alkali Stability pH4 Good Good Good
pH6 Excellent Excellent Excellent
pH7 Average Average Average
pH8 Normal Normal Normal
pH10 Poor Poor Poor
Good Good
Excellent Excellent
Good Good
Good Good
Poor Poor
Tab.2 Stability performance of the emulsion From Tab.2 we observed that the dilution stability and electrolyte resistance of polyurethane acrylate emulsion are good in condition and there is no any type of precipitation. It is also found that, with the increase of polyurethane chain to the polyacrylate chain the acid and alkali stability of the emulsion improves gradually up to pH label 8. 3.4 Gel ratio percentage of the polymerization
Fig.2 shows the effect of different amount of pu/pa percentage on the gel ratio of pua dispersion. The result indicate that, the gel ratio of the total residue increases significantly with the increase of polyurethane emulsion. The reason maybe that, total polyurethane pre polymer chain can’t react with the whole polyacrylate chain due to different system time and temperature parameters.
Fig.2 Polyurethane emulsion % vs gel ratio 1.4 1.3 1.2 1.1 1 0
2
4
6
8
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10
12
14
16
3.5 Particle size and particle size distribution analysis by laser particle size analyzer
Fig.3 shows the particle size and distribution of particle of the polyurethane-polyacrylate emulsion. Here we understand that, the minimum particle size of the emulsion was around 50 nm and the maximum particle size was 250 nm. Particles in the aqueous emulsion werefinally distributed, and the average particle size was 100 nm.
Fig.3 Particle size distribution analysis 3.6 Effects of different ratio PUA emulsion on the properties of yellow resistance
Fig.4 shows the influence of different ratio of PUA emulsion on the properties of yellow resistance. From the perspective of the specimen, yellow resistance improved gradually. This could be due to that, at the first PUA sample emulsion the percentage of polyurethanewas less compared with last sample emulsion.
yellow resistance
20 15 10 5 0 0
2
4
6
8
polyurethane %
10
12
14
16
Fig.4 Polyurethane emulsion % vs yellow resistance
4 CONCLUSIONS By using polyeather diol, butanediol, dimethylolpropionic acid,isophorone diisocyanate and acrylate monomers as the main materials, PUA emulsion can be prepared. When PU/PA percentage, the neutralization parameter and the process temperature are respectively controlled at 4% ̴11%, around 90%
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and about 75˚ ̴ 85˚, the emulsion is of better appearance, softer and better elasticity of PUA film, water resistance and meets the requirements of pigment printingapplication.
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