Note: Descriptions are shown in the official language in which they were submitted.
;;79L~
The present invention relates to a process for the
production of light resistant polyvinyl butyral foils.
More particularly,-the present invention relates to
plasticiser-containing foils of partially acetalised
polyvinyl alcohols which are used as bonding foils in
laminated safety glasses. Most particularly, the invention
relates to the production of new polyvinylbutyral foils and
to the use of these foils for the production oE laminated
safety glasses.
]0Laminated safe~y glasses consist in general of two
silicate glass panes and an adhesive foil connecting the
; glass panes. Optionally, one of the silicate glass panes
can be replaced by a plastics pane. Such laminated safety
panes are employed chiefly as windscreens in vehicles; they
can however also be employed in the building industry when,
according to their use, even more than two silicate or
plastics panes are connected by adhesive foils. Such
multiple laminates serve Eor example as laminated armoured
glasses. The laminated safety glasses are produced by
compressing the Eoils and the glass panes at 5 to 20 ~p/cm
and 125 to 155 C in a press or, particularly preferably, in
an au-toclave.
Plasticised partially acetalised polyvinyl alcohol
foils serve chiefly as adhesive foils in composite glasses.
The partially acetalised polyvinyl alcohols necessary for
their production are produced by saponification of polyvinyl
acetate and subsequent acetalisation with aliphatic
aldehydes with 3 to 10 C-atoms such as, especially,
formaldehyde, acetaldehyde, butyraldehyde. The
saponification is, in general, not carried out completely so
that the polyvinyl alcohols generally still contain 0.5 to 5
weight ~ acetyl groups, --
,,
1 calculated as vinylacetate groups. ~ven theacetalisation is in gen~ral not completely carried out so
thak the partially acetalised polyvinyl a7cohol e~ployed
~or the production of the foils generally still contain
5 free O~-groups, with the partially butyralised polyvinyl
alcohol (in the following, denoted by PVB), this OH
content can amount to between 10 and 27 weight
calculated as vinyl alcohol. Unless otherwise ind~cated the ter~
partialIy acetali ~ polyvinyl alcohol(s) in ~he following is
10 used both for partially acetalised as well as also for
partially butyralised polyvinyl alcoh~1.
In the production of laminated safety glasses,
these partially acetalised polyvinyl alcohols are
employed as foils with a definite plasticiser content.
15 The type and amount of the plasticiser employed influence
the properties of the laminated safety glass. In
practice, it has therefore become clear that an
especially splinter proof laminated safety glass should
have as intermediate foil a PVB foil which possesses a
20 plasticiser content of 15 to 40 weight 4, preferably 25
to 31% and whose content of free O~ groups amounts to 10
to 25 weight ~, preferably 16 to 23 weight ~, related to
plasticiser-free PVB resin. The moisture content of
such a PVB f oil should lie between 0.2 and 0.9 weight ~.
The invention relates especially to foils of
plasticised partially acetalised polyvinyl alcohols with
good oxidation and temperature resistance and outstanding
light resistance. Plasticiser-containing polyvinyl-
butyral is exposed under the conditions for its working
30 to foils and the sub~e~uent working to laminated glass to
high temperatures which lead to a certain extent to
yellowing. The optical properties are in this way
especially deteriorated.
It is known that, to use phenolic compounds, such
35 as 2,6-di-tert.-butyl-p-cresol, 2,4,6-trimethylphenol,
octylphenol, bornyl-xylenol etc. to stabilise the
material ~German Patent Specification 2 208 167).It is
4~
1 further known that phosphorous -acid triesters such as
trilaurylphosphite, decylphenyl-phosphite etc. are used
for avoidance of yellowing (German Patent Specification 2
~0~ 167~.
In contrast to soft PVC formulations, in which the
initial colour, transparence and light stability is
improved by employment of phosphorous acid triesters as
co-stabilisers, it has however been shown that
phosphorous acid triester-containing PVB foils lose their
1~ original bright colour after longer periods in the light
and become yellow to an extent which cannot be dealt
with. In particular, with the water clear safety glass
; foils required, most recently by users, the task of the
present invention has been to find a way to improve the
15 long ter~l light stability and to prevent, in the course
of time, increasing yellowing.
Yellowing by exposure to light for a long time was
observed with use of a series of phosphorous acid
triesters or phosphonous acid diesters such as, for
20 example decyl-diphenyl-phosphite, trilauryl phosphite,
didecyl-phenyl-phosphite, tris-nonylphenylphosphi~e,
triphenylphosphite, trist2,4-di-tert.butylphenyl)
phosphite, di-~isodecyl)-pentaerythrityl-diphosphite,
di-stearylpentaerythrityl-diphosphite, tetrakis-
(2r4-di-tert.-butylphenyl)-4~4l-biphenylylenedi-
phosphonite.
There therefore existed the object of stabilising
the polyvinylbutyral foils, that is PVB ~oils in
laminated safety glass with contents of the indicated
30 phenollc compounds and sta~ilisers based on phosphorous
acid triesters and/or phosphonous acid diesters by
additional measures against the influence of daylight,
specifically, or periods of use of laminated safety
glass panes with PVB foils contained therein over years,
35 to achieve a protection against ageing with prominent
long term effect against yellowing.
Surprisingly, it has now been found that a long
3L~6~4~3
term efEect against yellowing of phosphite-containing foil
formulations is achieved by -the addition of selected UV-
absorbers and the yellowing achieved by the necessaryaddition of phosphite or phosphonite, even with longer
action of light, is prevented.
` An object of -the invention is therefore to provide
a process for the production of a foil of phenolically
stabilised, plasticised, partially acetalised polyvinyl
alcohols of superior oxidation-, temperature- and light-
stability, by using, in addition to phosphorous acid
triesters or phosphonous acid diester~s, further selected UV-
absorbers.
A further object of the inven-tion is to use such a
foil as a component of laminated glass.
In meeting these objects, -the invention provides
laminated glass having as a component a foil, having
superior resisance to oxidation, heat and light, comprising
phenolically stabilized, plas-ticized, partly acetalated
polyvinyl alcohols containing phosphorous-acid triesters and
phosphonous-acid diesters and at least one UV-absorber
having a long-term action, selected from the group
consisting of:
a) derivative of benzo-triazole
b) deriva-tives of acrylonitrile or cinnamonitrile
c) hydroxybenzophenones
and their mixtures.
The invention also provides certain foils used in
the above laminates.
The UV-absorbers are added as protection against
aging and have pronounced long-term action agains-t -the
yellowing resulting from exposure to daylight.
Surprisingly, the UV-absorbers used in the method
of this invention achieve the re~uired protection against
aginy and the long term effect against yellowing in
~i6'~0
fulfilment of -the above objec-ts. Other groups of the usual
UV absorbers, ln contrast fail to work.
For example, the phenyl salicylates and
derivatives thereof known as UV-absorbers, such as phenyl
salicylate, 4--tert.butylphenyl salicylate or 4-octylphenyl
salicylate, and the sterically hindered amines likewise
acting as liyht protective agents, such as for example
sebacic acid-bis-2,2,6,6--tetramethyl-4-piperidyl ester, do
not yield the indicated long-term effec-t and show too high E
1~ or YI values in the long term -test.
According to the inven-tion, suitable UV-absorbers
in the previously noted classes of material are:
1. Derivatives of benzotriazole, especially hydroxyphenyl-
benzotriazole, such as:
i
- 4a -
674~
1 2-(2'-hydroxy~5l-methylphenyl)-benzotria~ole~
2-(2'-hydroxy-3', 5'-di-tert.butylphenyl) 5-
chlorbenzotriazole, 2-(2'-hydroxy-3',5'~di-tert.
butylphenyl)-benzotriazole, 2-~2'-hydroxy-3'-tert.
butyl-5-methylphenyl-5-chlorbenzotriazole, 2~(2'-
hydroxy-3',5l-di-tert.amylphenyl)-benzotriazole,
2-t2'-hydroxy-5'-tert.octylphenyl)-benzotriazole.
2. Derivatives of acrylonitrile or of cinnamonitrile
fox example ~-cyano-B,~ diphenylacrylic acid ethyl
ester, ~-cyano- ~ -me~hyl-4-methoxycinnamnic acid
methyl ester.
3. Hydroxybenzophenones such as:
2,~'-dihydroxy-4-methoxy-benzophenone, 2-hydroxy-
4-n-octyl-oxy-benzophenone, 2-hydroxy-5-chloro-
benzophenone, 2,2',4,4'-tetrahydroxybenzophenone.
Mixtures of such UV-absorbers from the same or
different classes of materials are possible.
The use of those W-absorbers which possess no
colour of their own or whose own colour is less or which
20 do not achieve any colouration of the foil material, e.g.
2-t2'-hydroxy-5'-methylphenyl)-benzotriazole or ~-cyano-
diphenylacrylic acid ethyl ester is advanta~eous.
It often suffices to limit to addition amounts of
UV absorber of 0~1 to 0.2 weight %. In general the use
25 of 0.01 to 0.40 weight ~, preferably of 0.03 to 0.30
; weight %, succeeds.
The long term effect of the added UV-absorber was
measured in exposure experiments on composite glasses of
0.8 mm PVB foils between two 2.8 mm glass panes in the
30 rotation solarium according to German Utility Model 78 19
931 at intervals of 1 week to a total of 20 weeks. For
the purposes of appraisal, the total colour difference E
according to DIN 6174 or the Yellowness Index (YI)
according to ASTM-D-1925 is determined.
In the following Examples, for the purpose of
comparability, the same basic composition of PVB foil and
the above indicated thickness of a composite glass are
o
l chosen, with like reductions o~ measured values being,
however, achieved by the addi~ion of the W absorber
according to the invention in further PVB compositions.
Exam~
S A PVs foil of 0.8 mm thickness suitable for the
production of vehicle panes, based on a basic composition
of 70 weight 4 of partially butyralised polyvinyl alcohol
with 20 weight ~ polyvinyl alcohol content, 30 weight %
triethyleneglycol ester with 2-ethylbutyric acid as
lO plasticiser and 0.3 weight ~ bornyl-xylenol as phenolic
stabiliser, as well as, in the Comparative Examples 2 to
6 with a phosphite or phosphonite as additive was
compounded and thereupon worked up to foils.
Comparative Examples l to 6
The following stabilisers were employed as
additives for the indicated basic composition;
!. a = Decyldiphenyl phosphite
b = Tris(2,4-di-tert.butylphenyl)phosphite
c = Trisnonylphenyl phosphite
20 d = Di-stearyl-pentaerythrityl diphosphite
= Tetrakis~2,4-di-tert.butylphenyl)-4,4'-
bisphenylylene diphosphonite
.
weight % Total colour difference Yell~ess-Index
of additive ~ E with reference after
25to Standard after
_ _ l week lO weeks 20 wee~ l week lO weeks 20 weeks
1 None D.73 D.31 1.79 1.17 1.76 2 79
2 0.1 a D.61 1.BL 4.5Z D.72 2.76 4-73
3 0.1 b 0.91 1.D6 3.53 0.99 2.57 4-2D
30 4 D.1 ~ D.77 1.72 4.4 4 D 9D 2 .77 ~ . 62
D.1 d 1.D7 1.5B 4.22 D.77 Z.4D 4.37
6 0.1 e D-67 1.0~ 3.24 D.9D 2.1L 3.69
The addition of phosphites or phosphonites
achieves in the long term test increased colour values
35 which are perceived by the human eye as yellow
- 6 -
.. . . .~
~Z~67~0
l colouration.
Exam~es 7 to ll
2-(2' hydroxy-5'-methylphenyl)-benzotriazole (m)
was additionally added, as W-ab~orber according to the
5 invention to the basic PVB foil composition, provided
with the additives according to Comparative Examples 2 to
.
~ight ~ weight ~ ¦Total colour difference Yellowness-Index
of addi- W- ~ E with reference after
tive Absorber to Standard after
_ _ m _ _ 1 week lO week 20 week ,1 week 10 wee~
0,10 ~.1 D.65 0.~5 0.~ 0.~9 1.D9 1-7~
D.lb 0.1 D.63 D,91 D.~6 1.~9 1.3Z l,D9
9 0.1c D.1 1.DL D ~2 0.95 1.35 1.5? 1.65
1D D-1d 0-1 D.63 D 53 D.56 D.9~ 1.2Z 1-35
15~1 D.le D.1 0 6D . D 72 D.9a 1.16 1.D9 1.1
The measured values of the long term test show
essentially lower colour values with respect to the
2Q associated Comparative Examples 2 to 6. Practically no
yellow colouration is perceivable with the eye.
Examples 12 to 14
To the basic PVB foil composition, provided with
the additive of Comparative Example 2, were additionally
25 added the below indicated UV-absorbers according to the
invention:
n = 2-(2'-hydroxy-3l,5'-di-tert.butylphenyl)-5-chlor-
benzotriazole
o = 2-hydroxy-4-n-octyloxy benzophenone
30 p = ~yano-~,~-diphehylacrylic acid ethyl ester
weight ~ weight ~ Total colour difference Yell~ess-Index
additive W-Absorb- ~ E with reference ~ter
er to Standard after
_ _ 1 week lO weeks 20 wee~ 1 week 10 weekc ~ S
1Z 0.1~ D.1 n 0.59 1.0~ 2.59 1.06 1.87 3.29
35 13 0.1a n.l O 1.01 D.59 0.63 0.7B 1.1~ 1.56
14 D.1a D.1 p 0.90 0.~6 Z.36 0-9~ 1.B2 2.B0
The measured values in the long term test also
~2667~
,
1 show for the UV-absorber n from the group of
ben~otriazoles~ o rom the group of benzophenones and p
from the group of cyano acrylates reduced values with
respect to Comparative Example 2 and very low yellow
5 colouration on visual observation.
Comparative Examples_15 and 16
Corresponding to the proceeding Examples, there
were employed substance q from the group of salicylates
and r from the group of piperidyl esters of dicarboxylic
10 acids, which however fail.
q - phenyl salicylate
r = sebacic acid-bis-2,2,6,6-tetramethyl-4-piperidyl
ester
~:ight % weight % Tbtal colour difference Yellowness-Index
15 additive W-Absor~- ~ E with reference after
er to Standard after
1 weekllO weeks O weeks 1 week 10 wee~ 20 w~ ks
_ . ~ ................ _ _._
15 0.1z 0.1 q ~.69 4.05 6~9~ 1 08 b.96 7.03
16 D-1n 0.1 r 0.42 1.38 3.56 1.33 3.D~ 5.~2
The results of the long term test show the
unusability of substances q and r, whereas with shorter
experimental periods disadvantages are not perceivable.
Yellow colouring is perceivable with the eye after the
long term test.
25 Examples 17 to 34
To the basic composition, provided with the
additive of Comparative Example 2, are added the
UV-absorbers m, o and p in the below indicated amounts:
I
74~
weight weight ~ llbtal colo~r difference Y~llD~ness-lndex
addi- W-Absor- ,~ E w.ith reference after
ive ber ~o Sta ,dard aft r
_ . _ ~ O wee~s ~0 weeks 1 week lO ~eek 20 wee~
17 0-1 a D.D1 ~~.77 2.Z7 5.34D,B9 3.16 5.63
50-1 ~ D.D3 ~0.73 1.~', 4.50 D.6~ 2.65 ~.91
D.1 s D.05 m0.96 0.56 2-35D.B5 1.69 3.25
.1 a D 07 mD .66 0. 5D 2D2 ~.B~ 1.41 2 .7L
0.1 e D.10 m~.6~ D.45 D.8~D.g9 1.09 1.2~
22 0.1 ~ D.2D m1-25 D.97 G.B61!1~ 1.~ D.67
lO23 D 1 ~ 0. al DD.5~ 1.36 .. 0.6a 2.D6 4-96
D-1 ~ 0.03 DO 66 D.74 3-42D.~f 1.42 3-32
O 1 ~ D. D5 oO .9D O .56 2-f~6 D .90 1-39 3.05
D.1 ~ D. D7 o1 .1~ D.53 1 55D . BE 1 .Z8 Z .35
D .1 ~ D .1D D1 .0 1 D .59 0 63 0 7~ 1; 1~ 1. 56
15ZB D.1 ~ D-Z0 D1.09 D.6D 0-60D-96 1.22 1.36
_ _ .
Z9 0.1 ~ D.D1 p0.75 D.~ 4.511-4D 1-90 4.47
D.1 ~ O-D3 p .91 1.65 6 .70 D-61 ~ sn 6 .74
0.1 ~ 0.05 p.61 1.03 4-921.03 2-32 5.06
0.1 a 0 D7 p.65 1.1~ 3-66D-~7 2-lB 3.~3
D. 1 e 0 . lD p 0 .9D0 .a6 2 .36 0 9~ 1 .a2 2.8D
3~ D. 1 a ~ .2D p D .530 .55 1.6~ 1.16 2 15 2 .53
_. . . . _
In the long term test, with additive a~,ounts of
O.Ol to 0.03 weight ~, improvements in the colour values
25 are perceivable. Additive amounts between O.l and 0.2
weight % give very low colour values for special
requirements or especially long periods of employment.
I
_ g _
