Note: Descriptions are shown in the official language in which they were submitted.
i281526
This invention relates to an improved interlayer
for a laminated glass used in various transportation facil-
ities such as automobiles and aircraft and windowpanes of
buildings.
The laminated glass is produced generally by
holding an interlayer of a film or sheet of, for example,
plasticized polyvinyl butyral with two glass sheets to
build an assembly, removing air from the inside of the
assembly under reduced pressure by using a rubber bag,
10 etc., preliminarily press-bonding the constituents of the
assembly, and then consolidating it in an autoclave to form
a unitary structure. Raised and depressed portions of
various shapes are formed on one or both surfaces of the
interlayer to improve deaeration in the preliminary press-
bonding step and prevent blocking of the interlayer, as
disclosed, for example, in Japanese Laid-Open Patent
Publication No. 150532/1982. So far, however, no inter-
layer film has been obtained which is satisfactory both in
deaeratability and antiblocking property.
It is an object of this invention to provide an
interlayer film or sheet for a laminated glass, which has
excellent deaeratability in the press-bonding and consoli-
dating steps, improved antiblocking property and moderate
adhesion to glass.
The present invention provides an interlayer for
a laminated glass, which is composed of a film or sheet of
a thermoplastic resin, at least one surface of the film
or sheet of a thermoplastic resin having numerous coarse
raised and depressed portions and numerous fine raised and
depressed portions existing on the surfaces of the coarse
raised and depressed portions, the average distance between
two adjacent coarse depressed or raised portions being
about 2 to about 10 times the 10-point average roughness
~, of the coarse raised and depressed portions measured in
-~ 35 accordance with ISO`-R46~. %
128~526
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In a preferred embodiment of this invention, the
average distance between the two adjacent coarse raised or
depressed portions is 100 to 500 micrometers, preferably
200 to 300 micrometers, and the 10-point average roughness
of the coarse raised and depressed portions is ~ to 100
micrometers, preferably 25 to 70 micrometers.
The surface roughness of the fine raised and
depressed portions formed on the surfaces of the coarse
raised and depressed portions, and the distance between
adjacent fine raised or depressed portions are selected
within proper ranges depending mainly upon the roughness of
the coarse raised and depressed portions, and the material
and properties of the thermoplastic resin. Usually, the
surface roughness of the fine raised and depressed por-
tions, determined by the 10-point average roughness, is 5
to 20 micrometers, peeferably 5 to 15 miceometers.
When the average roughness of the coarse raised
and depressed portions is relatively small, it is desirable
to make the surface roughness of the fine raised and de-
pressed portions relatively small. Preferably, the ratioof the surface roughness of the fine raised and depressed
portions to the surface roughness of the coarse raised
and depressed portions is in the range of from 0.2 to 0.5.
The average distance between two adjacent fine raised or
depressed portions is preferably 60 to 130 micrometers,
more preferably 60 to 100 micrometers.
The invention is described below in detail with
reference to the accompanying drawings in which:
Figure 1 is a partly broken-away perspective
view, drawn in a slightly exaggerated manner, showing the
state of the interlayer of the invention being held by
glass sheets; and
Figure 2 is a surface roughness curve of the
interlayer of the invention at a certain position drawn in
a slightly exaggerated manner.
With reference to Figure 1, numerous coarse
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raised portions 4 and depressed portions 5 (inclusively
designated by 2) are formed on both surfaces of an inter-
layer 1, and numerous fine raised and depressed portions
3 are formed on the surfaces of the coarse raised and de-
pressed portions 2, and the surfaces of the interlayer 2have double raised and depressed areas.
Preferably, a depressed portion S of the coarse
raised and depressed portion 2 is directly connected to the
depressed portion 5 of the adjacent raised and depressed
portion 2, as shown in the drawing. If desired, the de-
pressed portions 5,5 of the adjacent raised and depressed
portions 2,2 may be connected through a flat portion. In
the latter case, the area of the flat portion is preferably
minimized in order to increase the antiblocking property of
the interlayer.
In the illustrated embodiment, the coarse raised
and depressed portions are arranged irregularly on the
surface of the interlayers, but if desired, they may be
arranged regularly. If further desired, the coarse raised
portions may be connected in a long line in one direction
to form ridges, and a narrow channel may be formed between
adjacent ridges. In this case, however, it is necessary to
remove air during laminated glass production in a direction
nearly corresponding to such a narrow channel.
Referring to Figure 2 showing a surface roughness
curve of the interlayer 1 at a certain position measured by
using the needle contacting method.
The average distance of adjacent coarse raised or
depressed portions is measured, for example, as an average
of distance between the bottoms of the adjacent coarse
depressed portions. Let us consider the surface roughness
curve of Figure 2 with respect to a part having a standard
length L. Let the distance between the bottoms of two
adjacent depressed portions be Wi (where i is an integer
of 1 to n, and n+l is the number of the bottoms of de-
pressed portions existing in the standard length L), then
~Z815Z6
the average distance W is given by the following equation.
n
W= ~ Wi/n
i=l
The standard length L is assumed to be 8 mm.
The roughness of the coarse raised and depresssed
portions is expressed by the 10-point average roughness in
accordance with ISO-R468 of International Organization for
Standardization, and determined as follows:-
In the curve shown in Figure 2 obtained by theneedle contacting method with respect to the standard
length L, tbe 10-point average roughness H is defined as
the average of the heights of five ridges from the highest
ridge 41 to the fifth highest ridge 45 minus the average of
the depths of 5 valleys from the deepst valley 51 to the
5th deepst valley 55. Hence, in Figure 2, H is calculated
in accordance with the following equation.
(Hl+H2+H3+H4+H5) - (H6+H7+H8+H9 10
H = 5
Hl to Hlo represents the height or depth of a
ridge or valley measured from the reference line X.
The standard length L is determined according to
the degree of the surface roughness, but in the present
invention, it is set at 8 mm~
In the present invention, W and H are selected so
that the average distance W of the coarse raised and de-
pressed portions is about 2 to about 10 times the 10-point
average roughness H.
If the average distance W is less than 2 times
the average roughness H, air tends to remain during pre-
liminary press-bonding of glass sheets 6, 6 and the inter-
layer 1, and therefore, foams tend to occur in the lam-
inated glass obtained by the subsequent consolidating opera-
tion. If the averge distance W exceeds 10 times the average
.
~;2B~26
roughness H, the interlayer blocks, or its adhesion to the
glass is too strong, and the operability of laminate glass
production is reduced.
The 10-point average roughness of the fine raised
and depressed portions is measured after the coarse raised
and depressed portions (also called undulations) are removd
from the surface (sectional) curve shown in Figure 2.
Removal of the coarse raised and depressed portions from
the sectional curve is carried out generally by using a
filter circult used in an electrical surface roughness
tester, or by utilizing the locus of the center of a circle
having a large radius of curvature obtained when the sec-
tional curve is traced with the circle. The method using
a filter circuit is preferred. Most of needle-contacting
type surface roughness testers now in use are adapted to
electrically amplifying the movement of a contact needle,
and the aforeaaid filter circuit is usually built within
the testers. One example of the surface roughness test
containing a filter circuit built therein is Surfcom 1210A
(a contact needle type surface roughness tester made by
Toyo Seimitsui Rabushiki Kaisha).
In the present invention, it is preferred to
employ 0.08 mm as the length of cutoff in the filter cir-
cuit in accordance with Japanese Industrial Standard, JIS
B-601-1976.
Examples of the thermoplastic resin used to form
the interlayer in accordance with this invention include
polyvinyl butyral, polyurethane, ethylene/vinyl a~cetate
copolymer, ethylene/vinyl acetate/vinyl alcohol copolymer,
and ethylene/methyl methacrylate copolymer. For use in
automobile laminated glass, the use of plasticized poly-
vinyl butyral is preferred.
The interlayer of this invention may have various
known additives, such as ultraviolet absorbers, antioxi-
dants, coloring agents and adhesiveness adjusting agents,contained therein or adhering thereto. For various end
1'~815~6
usages, the thickness of the interlayer is preferably in
the range of 0.1 to 2.0 mm.
The interlayer film or sheet having a double
raised and depressed pattern may be produced by using
an embossing roll method, a calender roll method, an ir-
regular-shape extruding method, or a mechanical etching
method. The emboss roll method is preferred. According
to the emboss roll method, emboss rolls having raised and
depressed portions corresonding to the raised and depressed
portions to be formed on the surface of the interlayer film
or sheet are used as press-forming rolls in the production
of the interlayer.
In the formation of the double raised and de-
pressed pattern on an embossing roller used for the produc-
tion of the interlayer of the present invention, it ispreferred to use an engraving method for the formation of
coarse raised and depressed portions and a blasting method
for the formation of fine raised and depressed portions.
According to the engraving method, the desired pattern is
engraved on a mother roll, and the pattern on the mother
roll is transferred under pressure to the surface of a roll
to be produced. According to the blasting method, a par-
ticulate blasting material is blown against the surface
of a roll at a high speed. The blasting material is, for
example, Alundum (artificially fused alumina), emery and
steel grids obtained by crushing steel shots. Emery is
preferred.
Since the engraving method can give raised and
depressed portions having a relatively uniform and stable
configuration or roughness, it is useful in forming coarse
raised and depressed portions which impart deaeratability
to the interlayer. According to the blasting method,
nonuniform but relatively steep raised and depressed por-
tions can be obtained, and therefore it is useful for
forming fine raised and depressed portions which impart
antiblocking property to the interlayer.
~;
-- 7 --
A laminated glass containing the interlayer of
this invention may be produced usually by holding the
interlayer between an inorganic glass sheet and an in-
organic glass sheet or between an inorganic glass sheet
and an organic glass sheet composed of a transparent rigid
resin such as a polycarbonate resin or an acrylic resin,
and removing air from the inside of the assembly by placing
it in a rubber bag or by using nip rolls and squeezing it
between the rolls to preliminarily press-bond the consti-
tuents of the assembly, and thereafter consolidating it athigh temperatures and pressures in an autoclave. As a
result, a transparent laminated glass can be obtained.
The preferred embodiments and advantages of this
invention are illustrated by the following Examples and
Comparative Examples.
In the following examples, the antiblocking
property of the interlayer film or sheet and the foaming of
the laminated glass by heating were measured by the follow-
ing methods.
(1) Antiblocking property
The interlayer was cut into pieces having a size
of 100 mm x 25 mm. Two pieces were laminated and a load of
2 kg was placed on the laminate. It was left to stand at
room temperature for 24 hours. Then, the laminate was
subjected to a 180 degree peel test at a pulling speed of
200 mm/min. The average (three replicates) of the peeling
forces was calculated, and defined as a measure of anti-
blocking property.
The larger the value, the higher the adhesion
strength between the film pieces, and therefore the worse
the operability of laminated glass production.
(2) Foaming
The interlayer was held between two inorganic
glass sheets, and the resulting assembly was passed through
a heating oven. The surface temperature of the heated
laminate was adjusted, and air was removed from inside the
assembly by a squeezing method using nip rolls to perform
preliminary press-bonding.
The laminated product was then consolidated in
a pressurizing device at a pressure of 13 kg/cm2 and a
5 temperature of 130C. Then the temperature was lowered
to 50C, and the pressure was gradually lowered to atmos-
pheric pressure. Ten such laminated glasses were placed in
a Geer's oven, and heated at 120C for 2 hours. The number
of laminated glasses in which the remaining air became
10 foams was counted.
EXAMPLE 1
An interlayer film of plasticized polyvinyl
butyral was prepared in a customary manner from 100 parts
by weight of polyvinyl butyral and 40 parts of triethylene
15 glycol di-2-ethylbutyrate. By using embossing rolls,
a double raised and depressed pattern consisting of ir-
regularly arranged coarse raised and depressed portions and
fine raised and depressed portions formed on the surfaces
of the coarse raised and depressed portions was formed on
20 both surfacs of the interlayer film. The 10-point average
roughness of the coarse raised and depressed portions was
35 micrometers, and the average distance between adjacent
coarse raised or depressed portions was 5 times the 10-
point average roughness. The configuration of the coarse
25 raised or depressed portions was therefore gentle. The
10-point average surface roughness of the fine raised and
depressed portions was 8 micrometers.
The antiblocking property of this interlayer film
at room temperature and the foaming of a laminated glass
30 produced by using the interlayer film are shown in Table 1.
EXAMPLES 2-3
In the same way as in Example 1, interlayer films
having double raised and depressed patterns were produced.
The configurations of the raised and depressed portions and
35 the properties of the interlayer films and laminated glas-
ses are shown in Table 1.
- 9 -
COMPARATIVE EXAMPLE 1
In the same way as in Example 1, an interlayer
film having a raised and depressed pattern without fine
raised and depressed portions as shown in Table 1 was
S produced by using an embossing rDll. The antiblocking
property of this interlayer film and the foaming of a
laminated glass are shown in Table 1.
COMPARATIVE EXAMPLE 2
A commercial plasticized polyvinyl butyral in-
terlayer film having steel raised portions and deep de-
pressed portions on both surfaces was examined for the
shapes of the raised and depressed portions and properties.
The foaming of a laminated glass produced by using this
interlayer was also examined. The results are shown in
Table 1.
-- 10 --
.~_, ~ u. - 8 o o ~
~ ~ ~ ~; ~i! N O O
0~ O O
~ U~ O ~ ~ I~ O
aJI ~ ~ 0~
~1 O O ~ ~ U~ O _l
1~ ~ O ~`
~1 O
In ~ U~ CO a~ o
~`0
8 ~ ~ ~ & 'n
~o ~ n ~ ~ .
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In the interlayer of this invention, the average
distance between adjacent coarse raised or depressed por-
tions is about 2 to about 10 times the average roughness of
the coarse raised and depressed portions and no deep valley
nor steep ridge exists. Accordingly, air does not remain
in a step of holding the interlayer with glass sheets and
performing deaeration, and consequently, a laminated glass
free from foams can be obtained.
Since fine raised and depressed portions are
further formed on the surfaces of the coarse raised and
depressed portions in the interlayer of this invention,
the interlayer has good antiblocking property and does not
excessively adhere to glass sheets, the operability of the
laminated glass production is improved and the number of
laminated glasses which can be stored in the stacked state
increases.
Since the interlayer of this invention has the
foresaid double raised and depressed pattern on its sur-
face, the raised portions are easily collapsed at the time
of preliminary press-bonding step, the line speed of the
preliminarily press-bonding step can be increased.
