U.S. patent application number 10/347792 was filed with the patent office on 2003-07-31 for plasticized polyvinyl butyral and sheet.
This patent application is currently assigned to Monsanto Company. Invention is credited to D'Errico, John J., Jemmott, Berkeley A., Krach, Mary S., Moran, James R..
Application Number | 20030144396 10/347792 |
Document ID | / |
Family ID | 24323287 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030144396 |
Kind Code |
A1 |
D'Errico, John J. ; et
al. |
July 31, 2003 |
Plasticized polyvinyl butyral and sheet
Abstract
Polyvinyl butyral resin and sheet having a hydroxyl content less
than 19.5, preferably about 17 to 19 weight %, calculated as
polyvinyl alcohol, plasticized with a compatible amount of
triethylene glycol di-2-ethylhexanoate.
Inventors: |
D'Errico, John J.; (St.
Glastonbury, CT) ; Jemmott, Berkeley A.;
(Springfield, MA) ; Krach, Mary S.; (Longmeadow,
MA) ; Moran, James R.; (Longmeadow, MA) |
Correspondence
Address: |
BANNER & WITCOFF
1001 G STREET N W
SUITE 1100
WASHINGTON
DC
20001
US
|
Assignee: |
Monsanto Company
St. Louis
MO
|
Family ID: |
24323287 |
Appl. No.: |
10/347792 |
Filed: |
January 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10347792 |
Jan 22, 2003 |
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08580952 |
Dec 29, 1995 |
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6559212 |
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Current U.S.
Class: |
524/317 ;
428/411.1; 428/437; 524/315; 525/61 |
Current CPC
Class: |
B32B 17/10761 20130101;
Y10T 428/31504 20150401; Y10T 428/3163 20150401; C08J 2329/14
20130101; C08K 5/103 20130101; B32B 17/10605 20130101; C08J 5/18
20130101; C08K 5/103 20130101; C08L 29/14 20130101 |
Class at
Publication: |
524/317 ;
524/315; 428/411.1; 428/437; 525/61 |
International
Class: |
C08K 005/10 |
Claims
I claim:
1. Polyvinyl butyral resin having a hydroxyl content of less than
19.5 weight % calculated as polyvinyl alcohol, plasticized with a
compatible amount of triethylene glycol di-2-ethylhexanoate.
2. The plasticized polyvinyl butyral resin of claim 1 wherein the
hydroxyl content is about 17 to 19% polyvinyl alcohol.
3. A sheet formed of polyvinyl butyral resin having a hydroxyl
content of less than 19.5 weight % calculated as polyvinyl alcohol,
plasticized with a compatible amount of triethylene glycol
di-2-ethylhexanoate.
4. The sheet of claim 3 wherein the hydroxyl content is about 17 to
19% polyvinyl alcohol.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to plasticized polyvinyl butyral
(PVB) and more particularly PVB sheet containing compatible
plasticizer.
[0002] Plasticized PVB sheet is used in light-transmitting
laminates containing one or more rigid layers, such as glass, for
applications such as building and vehicle windows, show cases,
protective glass for pictures, documents and the like. The
plasticized sheet absorbs energy and prevents disintegration when,
for example, the head of a vehicle occupant strikes the rigid layer
of a laminate window after a sudden stop or a foreign object is
propelled against the outside of the laminate. The PVB resin
contains hydroxyl groups in the polymer chain to promote adhesion
to glass.
[0003] The plasticizer must be carefully chosen to contribute to a
balance of performance properties in the laminate. Cost/benefit
performance continues of importance in assessing plasticized PVB
for safety laminates having valuable commercial properties.
SUMMARY OF THE INVENTION
[0004] Now plasticized PVB formulations have been developed
exhibiting improved plasticizer and PVB compatibility (affinity of
resin and plasticizer for each other) in comparison with prior art
systems.
[0005] Accordingly, a principal object of this invention is to
provide plasticized PVB formulations exhibiting improved
compatibility of plasticizer with PVB resin.
[0006] Another object is to provide a compatible plasticized PVB
formulation wherein the plasticizer is synthesized from readily
available, relatively inexpensive starting materials.
[0007] These objects are achieved by polyvinyl butyral resin having
a hydroxyl content of less than 19.5, preferably about 17 to 19
weight % calculated as polyvinyl alcohol plasticized with a
compatible amount of triethylene glycol di-2-ethylhexanoate
(3GEH).
[0008] Also provided is a sheet formed of this composition.
BRIEF DESCRIPTION OF THE DRAWING
[0009] In describing the overall invention, reference is made to
the accompanying drawing which is a graphical representation of the
compatibility of 3GEH with PVB at various polyvinyl alcohol (PVOH)
contents in the PVB.
DETAILED DESCRIPTION
[0010] Triethyleneglycol di-2-ethylhexanoate in the PVB formulation
plasticizes the PVB resin. The resin-compatible effective amount
depends on properties desired in the laminate application.
Generally 35 to 45 parts plasticizer per 100 parts PVB resin (PPHR)
are used.
[0011] Compatibility of plasticizer and resin is important in
maintaining the integrity of the sheet in its interlayer
application between glass layers in a safety laminate on exposure
to all the various conditions the laminate and interlayer might
encounter in use. If plasticizer loss by exudation from the sheet
is too great, laminate performance is adversely affected insofar as
increasing the glass transition temperature of the sheet
composition and reducing laminate impact performance.
[0012] PVB resin has a weight average molecular weight greater than
70,000, preferably about 100,000 to 250,000, as measured by size
exclusion chromatography using low angle laser light scattering. On
a weight basis PVB typically comprises less than 19.5%, preferably
about 17 to 19% hydroxyl groups calculated as polyvinyl alcohol
(PVOH); 0 to 10%, preferably 0 to 3% residual ester groups,
calculated as polyvinyl ester, e.g. acetate, with the balance being
acetal, preferably butyraldehyde acetal, but optionally including a
minor amount of acetal groups other than butyral, for example
2-ethyl hexanal as disclosed in U.S. Pat. No. 5,137,954, issued
Aug. 11, 1992.
[0013] PVB resin is produced by known aqueous or solvent
acetalization processes reacting PVOH with butyraldehyde in the
presence of acid catalyst, followed by neutralization of the
catalyst, separation, stabilization and drying of the resin. It is
commercially available from Monsanto Company as Butvar.RTM.
resin.
[0014] Plasticized PVB as sheet at a non-critical thickness of
about 0.13 to 1.3 mm is formed by mixing resin and plasticizer and
preferably (in commercial systems) extruding the mixed formulation
through a sheet die, i.e. forcing molten, plasticized PVB through a
horizontally long vertically narrow die opening substantially
conforming in size to the sheet being formed, or by casting molten
polymer issuing from an extrusion die onto a die roll in close
proximity to the die exit to impart desired surface characteristics
to one side of the polymer. When the roll surface has minute peaks
and valleys, the side of the sheet contacting the roll will have a
rough surface generally conforming to the valleys and peaks.
Roughness on the other side can be provided by the design of the
extrudate die opening as shown, for example, in FIG. 4 of U.S. Pat.
No. 4,281,980. Other known techniques for producing a rough surface
on one or both sides of an extruding sheet involve specifying and
controlling one or more of the following: polymer molecular weight
distribution, water content and temperature of the melt. These
techniques are disclosed in U.S. Pat. Nos. 2,904,844; 2,909,810;
3,994,654; 4,575,540 and European Patent No. 0185,863. Embossing
downstream of the extrusion die also roughens the sheet surface. As
known, this roughness is temporary to facilitate deairing during
laminating after which the elevated temperature and pressure during
bonding of the sheet to glass melts it smooth. Lamination to glass
is according to generally known procedures.
[0015] Sheet of the invention optionally contain additives to
enhance performance such as dyes, pigments, ultraviolet light
stabilizers, antioxidants, adhesion control salts and the like.
[0016] The following Examples illustrate and do not limit or
restrict the invention. Amounts and percentages are in weight.
[0017] Properties reported in Examples are measured substantially
in accordance with the following procedures.
[0018] PVB Residual Hydroxyl (% PVOH): ASTM 1396.
[0019] Spontaneous Exudation--(S.E.) Measures plasticizer--PVB
resin compatibility at the extremes of expected operating
temperatures and humidity. Blend plasticizer and PVB formulated (in
terms of plasticizer amount) to a glass transition temperature Tg
of 31.+-.1.degree. C. for 8 minutes at 150.degree. C. in a
Brabender mixer equipped with sigma blades turning at 50 rpm. Using
a heated hydraulic press (149.degree. C., 5.5 MPa for 5 min.),
press the plasticized PVB into 0.76 mm thick sheets, cut into
17.5.times.38 mm samples, dry for 5 days in a desiccator and weigh
to get dry weight. Place samples in a wet desiccator (enclosed
chamber containing water to create 100% RH) held at various
temperatures for 7 days. Lightly wipe exuded plasticizer from
sample surfaces to remove exuded plasticizer and then dry the
samples in a desiccator for 5 days. Calculate weight loss as % of
initial plasticizer weight as spontaneous exudation.
EXAMPLES 1-5
[0020] Blend PVB resin having the noted PVB residual hydroxyl
content with various amounts of liquid 3GEH plasticizer, form into
sheet and test for compatibility using the Spontaneous Exudation
test. Formulate (parts plasticizer per 100 parts PVB resin) to give
31.+-.1.degree. C. Tg. Results are in Table 1 and (S.E.) the
drawing.
1TABLE 1 Example PPHR % PVOH 1 37.6 17.1 2 39.2 18.1 3 40.2 18.6 4
41.7 19.4 5 43.1 19.9
[0021] The spontaneous exudation results shown in the drawing of
Exs. 1-3 compared with Exs. 4, 5 illustrate the unexpected
compatibility of 3GEH plasticizer with PVB resin species over the
narrow range of 17.1 to 18.6% PVOH insofar as exhibiting less than
1% plasticizer loss across the entire spectrum of temperatures and
humidity likely to be encountered by PVB sheet in commercial use.
Though the graph of the drawing suggests that heating the
compositions of Exs. 4, 5 to elevated temperature, e.g. about
95.degree. F. (35.degree. C.) would avoid excessive exudation, this
cannot be done in commercial practice since at such high
temperature abutting layers of plasticized sheet in storage will
stick to each other (block). Less than 3% loss is considered the
maximum upper limit which should occur at less than 19.5% PVOH.
Preferred PVOH level is equal or less than 19%, for example about
17 to 19%.
EXAMPLES 6-9
[0022] Sheet of various 3GEH plasticized PVB formulations was
stored in roll form at 50.degree. F. (10.degree. C.) for about 9
months in a warehouse at sheet moisture content of about 0.4 to
0.6%. The sheet formulations were:
2 Example PPHR % PVOH 6 41 18.3 7 39.5 18.6 8 44 20.0 9 42 20.3
[0023] When these rolls were unwound and examined visually, the
sheet of Example 8, 9 had an unacceptable surface film of
plasticizer as compared with that of Examples 6, 7 which had none.
This confirms in commercial use the lab results of Examples
1-5.
[0024] The preceding description is for illustration only and not
to be taken in a limited sense. Various modifications and
alterations will be suggested to persons skilled in the art. The
foregoing, therefore, is exemplary only and the scope of the
invention is to be ascertained from the following claims.
* * * * *