A polymeric-shaped article for use as film such as microfilm, overhead projector film, reprographic film, layout base, etc., and for insulating capacitors, which has excellent transparent, slippery and dielectric properties, and the process for realizing the same, the polymeric-shaped article having a polar surface such as polyester, polyamide, polyolefins, polyimide, polyvinyl alcohol, polyethylene terephthalate or polyethylene-2,6-naphthalate, to which is bonded a multiplicity of nodules of TiO.sub.2, each nodule having a diameter in the range of from about 0.01 to about 10 .mu.m, a height or thickness in the range of from about 0.01 to about 0.5 .mu.m, and an area ratio of TiO.sub.2 to total surface of from about 0.01 to about 50%; and the process being that of exposing at least one side of the surface of the article to water vapor and bringing a tetrafunctional titanium compound such as TiCl.sub.4, tetraethyltitanate, tetraisopropyltitanate, tetra-n-butyltitanate or mixture thereof, into contact with the surface, the processing temperature being at least greater than 30.degree. C.

BRIEF SUMMARY OF THE INVENTION 
The present invention relates to a polymeric-shaped article having many 
nodules of TiO.sub.2 in the shape of isolated spots bonded to at least one 
side of the surface of a polymeric material by means of exposing said 
surface to water vapor. The TiO.sub.2 nodules are formed by adding a 
tetrafunctional titanium compound to the surface of the polymeric article 
either simultaneously with or after exposure of the surface area to water 
vapor. 
In polymeric articles, especially in films, sheets and fibers, slippery and 
transparent properties are essential. However, conventional methods for 
improving these properties have heretofore been both difficult and 
unsatisfactory. Although it has been possible in the past to improve the 
slip of a polymeric article, the improvements have been generally 
accompanied by an increase in haziness. For example, U.S. Pat. No. 
2,819,173 discloses means for obtaining a silky gloss by adding to the 
surface of a polymer 0.05.about.10% by weight TiO.sub.2 having a particle 
size smaller than 150 .mu.m, and British Patent No. 1,130,947 discloses 
that a slippery and thick film for use as slot liners is obtained by the 
addition of 1.about.15% by weight of an inert filler such as TiO.sub.2. 
British Patent No. 1,096,064 discloses means for improving the surface 
properties of a material such as slipperiness and opacity by coating or 
laminating one article containing a filler to the base article. However, 
these filler particles as disclosed above are generally of clay mineral 
containing some impurities which limit the productivity of polymerization 
or cause a color change in the polymer, and contain grains large enough to 
cause an abnormal increase in pressure during the filtering of the molten 
polymer. As a result, classification or graining is required to remove the 
large particles. Such a procedure, if it is to be environmentally safe, is 
both expensive and time-consuming. Additionally, the film disclosed in 
British Patent No. 1,096,064 is difficult to recycle as a raw material for 
reuse. 
Therefore, it is an object of the present invention to provide a polymeric 
article which is both slippery and transparent. 
Another object of the present invention is to provide a process for 
carrying out this invention in which good slipperiness is obtained 
independent of any charge in haze or transparency. 
A further object of the present invention is to provide a polymer-shaped 
article having excellent water-removal properties necessary in some 
processes for film conversion. 
A still further object of the present invention is to provide a film which 
is suitable as a base film for microfilm, reprographic film, graphic art 
film and for stationary use, which may be recycled as a raw material for 
reuse in film making and which has good dielectrical strength and 
therefore may be used as an insulator in capacitors. 
These and other objects of the present invention will become more apparent 
from the following detailed description. 
DETAILED DESCRIPTION OF THE INVENTION 
The tetrafunctional titanium compounds employed in the present invention 
are used in the form of vapor mixed with dry air or nitrogen and include, 
but are not limited to, titanium tetrachloride, tetraethyltitanate, 
tetraisopropyltitanate, tetra-n-butyltitanate and mixtures thereof. The 
tetrafunctional titanium compounds are contained in the gaseous vapor from 
about 0.1 to about 5% by volume, but more preferably from about 0.3 to 
about 3% by volume, in order to maintain uniform quality and ease of 
processing the products. When the tetrafunctional titanium compound has a 
high boiling point, high temperature or low pressure must be applied 
taking care not to damage the polymeric article. 
By the use of an electron probe X-ray microanalyzer, it can be seen that 
the area surrounding the TiO.sub.2 nodules after application of the 
titanium compound to the surface of the article is substantially free of 
titanium. 
The size of the small, isolated nodules of TiO.sub.2 can be observed 
through a microscope or a scanning electron microscope and it can be seen 
that the size of the TiO.sub.2 nodules vary, but this variation in size 
can be controlled as will be explained hereinbelow. 
The diameter of the TiO.sub.2 nodules is shown to be generally in the range 
of from about 0.01 to about 10 .mu.m, and preferably from about 0.03 to 
about 4 .mu.m, and further favorably from about 0.05 to about 3 .mu.m. The 
height or thickness of the nodules is from about 0.01 to about 0.5 .mu.m, 
and preferably from about 0.02 to about 0.3 .mu.m. 
By controlling the size of the nodules of TiO.sub.2 on the surface of the 
polymeric article so they will be within the above-mentioned ranges, it 
has been found that the slipperiness of the surface could be improved 
without any significant increase in haze or decrease in transparency. 
The ratio of the total area of the isolated nodules divided by the entire 
surface area is generally from about 0.01 to about 50%, and favorably from 
about 0.05 to about 20%, and even more favorably from about 0.1 to about 
10%. If the ratio is below about 0.01%, sufficient slip cannot be 
obtained. When the value of the ratio is beyond 50%, the original 
properties of the article can be seriously damaged. For example, the 
article may become too slippery to handle properly or may lose its 
original surface tension. 
In the present invention, the TiO.sub.2 nodules are bonded firmly to the 
surface of the base article without any change in surface properties as 
exemplified by pressing adhesive tape 10 mm in width to the nodules and 
then peeling the tape away from the surface of the article. 
The size of the TiO.sub.2 nodules depends on the amount of water vapor to 
which the surface of the article is exposed and to the temperature of the 
gaseous vapor containing the tetrafunctional titanium compound. 
In the process of exposing the surface of the article to water vapor, the 
best effect is achieved by exposing the surface to as much of the water 
vapor as is possible without the water vapor forming visible water 
droplets which would cause the nodules of TiO.sub.2 to be too large. 
Generally, the processing temperature should be maintained as high as 
possible without damaging the polymeric article. The processing 
temperature should be at least more than about 30.degree. C. and 
preferably at more than about 60.degree. C. If the processing temperature 
is lower than about 30.degree. C., the speed of reaction to TiO.sub.2 is 
so slow that the proper distribution and strong bonding of TiO.sub.2 to 
the surface does not occur. It is preferable that the temperature be 
controlled from about 90.degree. to about 200.degree. C. because within 
this range, many fine nodules are formed. 
Coating, corona treatment, flame treatment, grafting or other processing on 
the surface of the article of this invention before the appearance of 
TiO.sub.2 do not obstruct the manufacture or the effect of this invention. 
Polymers for use in the article of the present invention are preferably in 
the form of film and include, but are not limited to, polyesters such as 
polyethylene terephthalate and polyethylene-2, 6-napthalate; polyamides 
such as nylon 6 and nylon 66; polyolefins such as polypropylene; 
polyimides, polyvinyl alcohol and their copolymers. 
When the polymeric article of this invention is sheet or film, the article 
is generally made by a melt extrusion method if the material can be 
melted. The polymer is first dried to avoid adverse effects from the 
humidity and is then sent to a properly heated extruder in the form of 
chips or in the form of melted polymer. The extruder can be co-used with a 
gear pump, and sometimes only a gear pump is used. 
The melted polymer is extruded through a die near the extruder and is 
solidified quickly on a casting drum. If necessary, it is then oriented 
uniaxially or biaxially, and generally heat set. If the properties of the 
film are sufficient without orientation, then stretching of the article is 
not necessary. 
Biaxial orientation can be carried out in the order of machine direction 
and transverse direction or vice versa. In some cases, simultaneous 
biaxial stretching is also carried out and sometimes further drawing in 
one or two directions is performed after biaxial stretching. 
If a polymer cannot be extruded, the polymer is dissolved by means of a 
suitable solvent and then cast on a large drum or endless metal belt. The 
film is obtained by vaporizing the solvent. 
A calender method and rolling method are also known in the manufacture of 
film. The many small, isolated nodules of TiO.sub.2 of the present 
invention are combined with the surface of a non-stretched or uniaxially 
stretched sheet or film. When the sheet or film is stretched, dots of 
TiO.sub.2 are not drawn. Therefore, the area ratio of TiO.sub.2 to total 
area is greatly decreased giving the article clarity and slip, with the 
adhesion property being retained at the original level of the film. 
A method of manufacturing a rainbow pattern on a film by the gathering of 
light on a thin film of TiO.sub.2 which is made by spraying TiCl.sub.4 on 
a plastic film is also generally known, and polyethylene terephthalate is 
a known polymer for this film. Since the film in this case cannot be 
stretched, a film which has already been biaxially stretched and heat set 
is used. If drawn, the thin film of TiO.sub.2 is broken and then loses the 
rainbow color but in any case, this film will lose its value because the 
color of the TiO.sub.2 film changes from rainbow to opaque in one month or 
at longest in one year and a half under oridinary conditions. 
The stretching conditions for the polymeric article with TiO.sub.2 vary 
depending upon the polymer. For example, for polypropylene drawing is 
carried out from about 110.degree. to about 170.degree. C., with the 
drawing ratio being from about 5 to about 12 times in both directions. 
Polyethylene terephthalate is stretched from about 80.degree. to about 
130.degree. C., and preferably from about 85.degree. to about 120.degree. 
C. The drawing ratio in the machine direction is from about 2 to about 8, 
and preferably from about 2.5 to about 6. The ratio in cross section is 
from about 2 to about 5, and preferably from about 2.5 to about 4.0. 
Polyethylene-2,6-naphthalate can be extruded from about 280.degree. to 
about 320.degree. C. and stretched from about 105.degree. to about 
160.degree. C., and preferably from about 110.degree. to about 150.degree. 
C. The ratio is almost the same for polyethylene terephthalate. Polyamide 
such as nylon 6 is extruded from about 230.degree. to about 260.degree. C. 
and stretched from about 60.degree. to about 150.degree. C., and the 
ratio is about 6 to about 12 times. These films are generally heat set 
with the heat set temperatures also varying depending upon the polymer. 
For example, the heat-set temperature for polypropylene film is from about 
155.degree. to about 170.degree. C.; for polyethylene terephthalate or 
polyethylene-2,6-naphthalate from about 150.degree. to about 240.degree. 
C., and preferably from about 180.degree. to about 235.degree. C.; and for 
polyamide from about 150.degree. to about 210.degree. C. The effect of 
heat setting not only stabilizes the dimensions of the film but also 
accelerates the reaction of the non-reacted substance from a 
tetrafunctional titanium compound. 
As discussed previously, attempts to make a slippery film by addition of 
additives into the polymer have resulted in relatively hazy film. In the 
case of polyethylene terephthalate, biaxial stretching generally causes a 
planar refractive index larger than 1.57 and refractive index in 
directional thickness smaller than 1.57, and consequently, voids are 
created around the fillers, causing haziness in the film. With respect to 
the polymeric article of the present invention, the nodules or spots of 
TiO.sub.2 are independently bonded to the surface in the shape of a circle 
or ellipse, the size of which is from about 0.01 to about 10 .mu.m, 
resulting in a polymeric article having good slip, transparency and 
water-removal properties, and which can be easily handled and/or 
converted. 
The present invention is further illustrated by the following specific 
examples. In this connection, haze was measured by the ASTM D-1003 test; 
the coefficient of static friction was measured by the ASTM D-1894 test; 
and the heights of nodules or spots of TiO.sub.2 were measured by 
metallizing the film surface at a known low angle, thereby replicating the 
surface and viewing the replica by means of an electron microscope.

EXAMPLE 1 
An amorphous polyethylene terephthalate film having a thickness of 1.000 
.mu.m and an intrinsic viscosity of 0.602 measured in o-chlorophenol at 
25.degree. C., was exposed to moist air at 45.degree. C. for 0.5 seconds 
and thereafter to an atmosphere of dry air containing 0.41% by volume of 
TiCl.sub.4 and maintained at 50.degree. C. for 0.3 seconds. 
The treated amorphous film was subjected successively to a longitudinal 
directional stretch followed by a transverse directional stretch. The film 
was stretched to 3.3 times its original length in the longitudinal 
direction at 90.degree. C. and to 3.4 times its original width in the 
transverse direction at 95.degree. C., and heat set at 220.degree. C. The 
film of the present invention had a multiplicity of isolated nodules of 
TiO.sub.2 having a diameter of about 0.5 .mu.m and a thickness of about 
0.1 .mu.m on the surface of both sides of the film. The area surrounding 
each nodules was substantially free of titanic material and the total 
ratio of the area of the nodules of TiO.sub.2 to the area of film surface 
was about 0.8%. Additional results are summarized in Table 1 below. 
Table 1 
______________________________________ 
Reference Example 1 Control 
______________________________________ 
Coefficient of Static Friction 
0.4 &gt;2 
Haze (%) 1.3 0.3 
Light Transmission (%) 
86.0 88.0 
______________________________________ 
The properties of the film of the present invention after being maintained 
at room temperature and humidity for two years were equal to the original 
properties and the water-removal properties were excellent. 
EXAMPLE 2 
The general procedure of Example 1 was repeated; however, this time the 
film and air containing TiCl.sub.4 at 150.degree. C. were exposed to a 
moist atmosphere maintained at 130.degree. C. There was no exposure to 
moist air at 45.degree. C. The properties of the film are summarized in 
the following Table 2. 
Table 2 
______________________________________ 
Diameter of TiO.sub.2 nodules (.mu.m) 
0.7 
Thickness of TiO.sub.2 nodules (.mu.m) 
0.05 
Total Ratio of the area of TiO.sub.2 to the Area 
of film surface (%) 1.2 
Coefficient of Static Friction 
0.63 
Haze (%) 1.1 
______________________________________ 
Transparency of this film was excellent and the film was suitable for use 
as an overhead projector film. 
EXAMPLE 3 
The general treatment was repeated as in Example 1 except that dry air 
containing saturated vapor pressure of tetraisopropyl titanate at 
103.degree. C. or saturated vapor pressure of tetra-n-butyltitanate at 
130.degree. C. was used in place of the air containing TiCl.sub.4. 
Only one surface of each film was treated. After processing, the treated 
surface had many small isolated nodules of TiO.sub.2 having a diameter of 
about 0.2 .mu.m and a height of about 0.075 .mu.m. The treated surface 
showed surface and optical characteristics similar to those obtained in 
Examples 1 and 2. The area ratio of TiO.sub.2 to total area of the surface 
was about 0.9%. 
EXAMPLE 4 
The general procedure of Example 2 was repeated except that 
polyethylene-2,6-naphthalate was used as a base film instead of 
polytheylene terephthalate with the film after treatment being 
subsequently stretched to 3.2 times its original length in the 
longitudinal direction at 130.degree. C.; 3.5 times its original width in 
the transverse direction at 135.degree. C., and heat set at 225.degree. C. 
The properties of the film are summarized in Table 3. 
Table 3 
______________________________________ 
Thickness of film(.mu.m) 16 
Diameter of TiO.sub.2 nodules (.mu.m) 
0.8 
Height of TiO.sub.2 nodules (.mu.m) 
0.06 
Total Ratio of the area of TiO.sub.2 to the area of 
film surface (%) 1.1 
Coefficient of Static Friction 
0.53 
Haze (%) 0.20 
______________________________________ 
This film was found to have excellent optical and slip properties. 
EXAMPLE 5 
An amorphous nylon 6 yarn was exposed to dry air containing moisture vapor 
and 1% by volume of tetraisopropyltitanate at 115.degree. C. for 1.3 
seconds, then stretched to about 5.2 times its original length. The yarn, 
having a size of 105 D, was found to have many small isolated nodules of 
TiO.sub.2 on the surface, and exhibited good slip. 
EXAMPLE 6 
The general procedure of Example 1 was repeated, except that polypropylene 
having a thickness of 180 .mu.m was used as a base film instead of 
polyethylene terephthalate and after treatment, the film was stretched to 
5.0 times its original length in the longitudinal direction at 125.degree. 
C.; 8.0 times its original width in the transverse direction at 
160.degree. C., and heat set at 160.degree. C. The film was found to have 
many isolated nodules of TiO.sub.2 on its surface. Additional results are 
summarized in the following Table 4. 
Table 4 
______________________________________ 
Example 6 
Control 
______________________________________ 
Diameter of TiO.sub.2 nodules (.mu.m) 
0.8 -- 
Height of TiO.sub.2 nodules (.mu.m) 
0.12 -- 
Coefficient of Static Friction 
0.45 &gt;1.0 
Haze (%) 3.0 2.9 
______________________________________ 
An amorphous polyethylene terephthalate film having a thickness of 87 .mu.m 
was exposed to air containing moisture vapor and 0.32% by volume 
TiCl.sub.4 at 170.degree. C. for 0.4 seconds, and after treatment, the 
film was stretched to 3.9 times its original length in the longitudinal 
direction; 3.7 times its original width in the transverse direction at 
88.degree. C., and heat set at 225.degree. C. The results are summarized 
in the following Table 5. 
Table 5 
______________________________________ 
Diameter of TiO.sub.2 nodules (.mu.m) 
0.6 
Height of TiO.sub.2 nodules (.mu.m) 
0.15 
Coefficient of Static Friction 
0.65 
Haze (%) 0.9 
______________________________________ 
The film was found to have a dielectric strength 1.1 times as great as 
"Lumirror" C10 (polyethylene terephthalate) having the same thickness.