| 1. Chemical Formula |
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PVA(Polyvinyl Alcohol) |
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| 2. Applications |
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2-1 General Introduction |
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PVA(Polyvinyl Alcohol)-POLINOL®, is a water-soluble resin is produced by the hydrolysis
of polyvinylacetate which is made by the polymerization of vinyl acetate monomer. It is classified into two main groups
namely fully hydrolyzed and partially hydrolyzed grades.
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PVA(Polyvinyl Alcohol)-POLINOL®, as an environmentally sensitive water soluble polymer, is widely used
for textile warp sizing, adhesive, paper sizing agent, ceramic binder and also used in cosmetics, emulsion stabilizer, civil engineering, construction, pharmacy and electronic industries.
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DC Chemical. Co. Ltd has been operating technical service and laboratories for customer-oriented product development and
technology development. We are also committed to improve the quality of our products and to make on time delivery and
services to our customers.
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PVA(Polyvinyl Alcohol)-POLINOL® is
divided into various kinds in accordance to the degree of hydrolysis and degree of polymerization. The nomenclature each grade
is as follows;
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2-2 PVA(Polyvinyl Alcohol) Grades and Specifications |
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Grade |
Viscosity
(cps *1)① |
Degree of hydrolysis
(mol%) |
PH(4% aqueous
solution) |
Volatile②
(max%) |
ASH③
(max%) |
| Fully hydrolyzed
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F-05 |
5.5-6.5 |
98.0-99.5 |
5.0-7.0 |
5.0 |
0.7 |
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F-05A |
5.5-6.5 |
98.0-99.5 |
5.0-7.0 |
5.0 |
0.7 |
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F-17 |
27.0-30.0 |
98.0-99.5 |
5.0-7.0 |
5.0 |
0.7 |
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F-17A |
27.0-30.0 |
98.0-99.5 |
5.0-7.0 |
5.0 |
0.7 |
Intermediate
hydrolyzed |
M-17 |
28.0-32.0 |
94.5-96.5 |
5.0-7.0 |
5.0 |
0.7 |
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M-17A |
28.0-32.0 |
94.5-96.5 |
5.0-7.0 |
5.0 |
0.7 |
Partially
hydrolyzed |
P-24 |
44.0-52.0 |
86.0-89.0 |
5.0-7.0 |
5.0 |
0.7 |
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P-20 |
31.0-35.0 |
86.0-89.0 |
5.0-7.0 |
5.0 |
0.7 |
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P-17 |
21.0-24.0 |
85.5-88.5 |
5.0-7.0 |
5.0 |
0.7 |
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P-17A |
21.0-24.0 |
85.5-88.5 |
5.0-7.0 |
5.0 |
0.7 |
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P-05 |
5.0-5.6 |
85.5-87.5 |
5.0-7.0 |
5.0 |
0.7 |
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P-05A |
5.0-5.6 |
85.5-87.5 |
5.0-7.0 |
5.0 |
0.7 |
Special
Grades |
CT-000* |
17.5-20.5 |
84.5-87.5 |
5.0-7.0 |
5.0 |
0.7 |
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SP-07 |
6.6-7.0 |
85.5-87.5 |
5.0-7.0 |
5.0 |
0.7 |
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TK-97* |
6.4-7.0 |
79.5-81.5 |
5.0-7.0 |
5.0 |
0.7 |
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CL-05* |
5.0-5.6 |
76.0-80.0 |
5.0-7.0 |
5.0 |
0.7 |
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CL-O5A* |
5.0-5.6 |
76.0-80.0 |
5.0-7.0 |
5.0 |
0.7 | |
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①Brookfield viscometer,
UL-Adapter, 4% aqueous solution at 20℃ |
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②105℃,
2hr dry |
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1)We have powder grades
besides the listed above and following grades
are commercially available. (P-05S,P-17S,F-17S,P-24S,CL-05S
etc...) |
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2)The
above *grades are carboxylated modified PVA (copolymer) |
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2-3 Grade Selection by utility |
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| 3. PVA(Polyvinyl Alcohol) Properties |
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3-1. General Properties |
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Appearance |
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Specific Gravity |
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Bulk density |
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pH |
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Glass transition temperature |
58℃(P Grade) ∼ 85℃ (F Grade) |
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Melting Point |
150∼190℃(P Grade), 210~230℃
(F Grade) |
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Thermal stability
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Gradual discoloration about 100℃; darkens rapidly above 160 ℃, Gradual decomposition above 180℃as melting point is similar to decomposing temperature |
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Oil resistance |
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Not soluble in animal, plant and grease
oils | |
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Storage stability
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Indefinite when protected from moisture | |
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Solvent resistance |
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Not soluble in organic solvent | |
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Acid & alkali resistance |
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Softened or soluble in acid and alkali | |
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Color(10%solution) |
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Particle size |
More than 95% through 14∼120mesh screen | |
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3-2. Effect of Degree of polymerization and Degree of hydrolysis |
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Degree of polymerization |
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Decrease |
Increase |
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Increased solubility
Increased flexibility
Increased hydrophilic
Increase dissolving rate | |
Increase viscosity
Increase tensile strength
Increase adhesive strenth
Increase water resistance
Increase
solvent resistance
Increase dispersing power | | |
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Degree of hydrolysis |
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Decrease |
Increase |
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Increased solubility
Increased flexibility
Increased dispersing power
Increased hydrophilic
Increase
adhesion to hydrophobic surfaces | |
Increase tensile strength
Increase solvent resistance
Increase water resistance
Increase adhesion to hydrophilic
surface | | |
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3-3. Other properties |
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3-3-1 Solubility |
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PVA(Polyvinyl Alcohol), as a water-soluble resin dissolves easily in water, but solubility depends
on the degree of polymerization and degree of hydrolysis. The lower the degree of polymerization, the easier it dissolves
in water. In general partially hydrolyzed grades are dissolved easily than fully hydrolyzed grades. Also, the dissolution
rate of PVA(Polyvinyl Alcohol) depends on dissolution temperature.
The higher the temperature, the greater the rate of
dissolution. Partially hydrolyzed grades dissolve at room temperature more easily than fully hydrolyzed grades which is not
easily dissolved in room temperatures. Fully hydrolyzed grades has a different dissolution rate which varies according to
the degree of crystallinity but partially hydrolyzed grades show little susceptibility to heat treatment condition. |
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Figure 1. Solubility (4wt%) vs. temperature
Dissolution condition: 2000rpm, 30min. PVA/water=4/96(wt/wt)% |
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Figure 2. Solubility (10wt%) vs. temperature
Dissolution condition: 2000rpm, 30min. PVA/water=10/90(wt/wt)% |
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3-3-2 Refractive index of aqueous solution |
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Refractive index of PVA (Polyvinyl Alcohol)aqueous solution depends on concentration and temperature
of aqueous solution |
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3-3-3 Viscosity of the aqueous solution |
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As degree of polymerization and degree of hydrolysis
increase, the viscosity of the aqueous solution becomes higher and depended largely on the degree of polymerization rather
than the degree of hydrolysis. |
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3-3-4 Viscosity Stability of the aqueous solution |
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The viscosity of PVA(Polyvinyl Alcohol) aqueous
solution for fully hydrolyzed grades increases, according to storage time, and a gelation occurs. On the other hand, the gelation
does not occur. because PVA(Polyvinyl Alcohol) aqueous solution of partially hydrolyzed grades has high viscosity stability,
For fully hydrolyzed grades viscosity increase at a faster rate if the concentration becomes high and temperature decreases.
The higher the degree of hydrolysis and degree of polymerization, the more likelihood of having an decrease in the viscosity
stability. But PVA(Polyvinyl Alcohol) aqueous solution returns to original solution state by increasing the temperature and
agitation after gelation. To increase the viscosity stability, Thiocyanate, Phenol, Butyl alcohol, Isopropyl alcohol are added.
There must be careful to use these viscosity stabilizers because these are affecting the quality of final products. |
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3-3-5 Surface Tension |
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PVA(Polyvinyl Alcohol) aqueous solution decreases
surface tension of water and has functions as protective colloid. Surface tension of PVA(Polyvinyl Alcohol) aqueous solution
increases as the degree of hydrolysis increases, but there is only a little change in the degree of polymerization. In
case of grades with low degree of polymerization(P-05), the surface tension is as low as PVA(Polyvinyl Alcohol) having 80
mol% degree of hydrolysis. |
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3-3-6 Adhesion of the Solution |
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Wet Track |
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PVA(Polyvinyl Alcohol) has superior initial
adhesion compared with other natural water soluble polymer. The wet tack of PVA(Polyvinyl Alcohol) aqueous solution increases
with viscosity.
Aqueous solution of PVA(Polyvinyl Alcohol) has strong adhesion to hydrophilic substance and the adhesion
tends to increase with the degree of hydrolysis and polymerization. The adhesion behavior of PVA(Polyvinyl Alcohol) solution
differs according to each substance |
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3-3-7 Thermal properties |
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PVA(Polyvinyl Alcohol) changes to yellow in
color upon heating, and partially hydrolyzed grades melt at 150-190℃and
fully hydrolyzed grades melt at 210-230℃. PVA decomposes partly
around 200-250℃and rapidly decomposes above 250℃. The degree of crystallinity increases proportional to the thermal temperature
and time. |
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3-3-8 Mechanical properties of film |
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PVA(Polyvinyl Alcohol) film generally has good
mechanical properties, compared with other plastic films. . Mechanical properties are affected by relative humidity because
of plasticizing role of water. As relative humidity or amount of plasticizer increase, elongation and tear strength increase,
but tensile strength and young’s modulus decrease. |
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| 4. Contact Information |
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E-mail : dept2-2@dcchem.co.kr
Tel : +82-2-7279-465,413
Fax : +82-2-774-2735
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| 5. Others |
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5-1 Direction for Dissolution |
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5-5-1 Facility |
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PVA(Polyvinyl Alcohol) does not corrosive, so
a Carbon steel would be used, but Stainless steel is preferable. Sometimes, vessels coated with plastic or other materials
may be used. The dissolving vessel must be equipped with either low speed paddle-type agitator or high speed propeller-type
one. |
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5-5-2 Dissolving Method |
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PVA(Polyvinyl Alcohol) should be put into the vessel little by little, so as to prevent the formation of swelling lumps
which are very difficult to completely dissolve |
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(1) Fully hydrolyzed PVA(Polyvinyl Alcohol)
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Fully hydrolyzed PVA(Polyvinyl Alcohol) disperse
easily in water without lumps because of low solubility at room temperature. First charge the vessel with suitable amount
water. Next charge PVA(Polyvinyl Alcohol) with stirring at room temperature and then heat up to 95℃. PVA(Polyvinyl Alcohol) is dissolved completely after stirring for 30 to90 minutes,
depending on the effectiveness of stirrer and amount of PVA(Polyvinyl Alcohol). (see figure 3) |
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(2) Partially hydrolyzed
PVA(Polyvinyl Alcohol)
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Partially hydrolyzed PVA(Polyvinyl Alcohol)
is charged very with stirring at room temperature and then heat up to 90 ℃.
PVA(Polyvinyl Alcohol) is dissolved completely after stirring for 30 to 60 minutes. It is good to increase the temperature
to save dissolution time, because the higher the temperature of solution, the more likelihood of increases in the dissolution
rate. Partially hydrolyzed PVA(Polyvinyl Alcohol) is more likely to produce foam, so rapidly increased temperature or stirring
is to be avoided. (see Figure 4) |
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Figure 3 |
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Dissolution of fully hydrolyzed PVA |
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Figure 4 |
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Dissolution of partially hydrolyzed PVA |
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5-2 Storage |
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5-2-1 Power |
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PVA(Polyvinyl Alcohol) has high hygroscopicity
If open to ambient, PVA(Polyvinyl Alcohol) adsorbs slowly moisture. It is advisable to store in sealed container. |
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5-2-2 Packing |
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vessel: kraftpaper bag
Net weight: 20kg.500kg(Ton-Bag), 750kg(Ton-Bag) |
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5-2-3 Plasticization |
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Plasticizer is used when needed to give a flexibility to PVA(Polyvinyl Alcohol) film. There are Glycerine, Ethylene glycol,
Trethylene glycol, Urea, and Ethanol amine as the effective plasticizer. Among them, Glycerine is used in large quantity.
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5-2-4 Gelation |
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The most representative gelation agents are
borax and boric. The gelation of PVA (Polyvinyl Alcohol) aqueous solution occurs even with a small quantity. The gelation
occurs easily with the high degree of hydrolysis concentration of PVA (Polyvinyl Alcohol) aqueous solution.
Also, some
dye (Congo red) and pigment (china clay, titaniumoxide, calcium carbonate) cause the gelation and viscosity increases. Therefore,
the substances containing these must be handled carefully and be used after empirical tests. |
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5-2-5 Extender, thickening |
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There are Starch, CMC, Methyl cellulose, Polyacryl
amide, Alginic acid soda as a thickener and china clay, titan white, calcium carbonate, starch, dextrin, and casein as extender.
According
to PVA(Polyvinyl Alcohol) grades and concentration of mixture, these tend not to be mixed uniformly or become easily separated. |
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5-2-6 Antifoaming agent |
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Bubbles occur when starred partially hydrolyzed PVA(Polyvinyl Alcohol) aqueous solution. Antifoams are used to restrain
the occurrence of bubbles and get rid of the occurring bubbles promptly. The most effective antifoam is silicone antifoam,
but it causes dyeing stain because of water-repellent. |
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On the other hand, non-silicone antifoam do not cause the dyeing stain, but it has low foaming effect and does not
produce a long-term effect. Anti-foam is used according to directions. Generally 0.2-0.4wt% of non-silicon antifoam is used
here. |
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