U.S. patent application number 12/837195 was filed with the patent office on 2010-11-04 for permeable glass mat and method of preparation.
Invention is credited to Guodong Zheng.
Application Number | 20100279570 12/837195 |
Document ID | / |
Family ID | 40454986 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100279570 |
Kind Code |
A1 |
Zheng; Guodong |
November 4, 2010 |
PERMEABLE GLASS MAT AND METHOD OF PREPARATION
Abstract
Provided is a coated nonwoven mat prepared by the process of
passing a nonwoven mat over the surface of a binder or coating
slurry to touch the bottom side of the mat sufficiently to fully
wet the glass mat. The wetted nonwoven mat is then immersed in a
slurry of the binder or coating material to fully saturate the mat
with the slurry material. The process of the present invention
allows one to control the porosity of the saturated fibrous
nonwoven mat at high consistency with reduced scrap rate. The
saturated mat will have improved tensile strength.
Inventors: |
Zheng; Guodong; (Englewood,
CO) |
Correspondence
Address: |
JOHNS MANVILLE
10100 WEST UTE AVENUE, PO BOX 625005
LITTLETON
CO
80162-5005
US
|
Family ID: |
40454986 |
Appl. No.: |
12/837195 |
Filed: |
July 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11900848 |
Sep 13, 2007 |
7790240 |
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12837195 |
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Current U.S.
Class: |
442/180 ;
442/327; 442/394 |
Current CPC
Class: |
E04C 2/043 20130101;
Y10T 442/2992 20150401; D04H 1/587 20130101; B32B 5/022 20130101;
Y10T 442/60 20150401; B32B 2471/04 20130101; B32B 13/14 20130101;
B32B 17/02 20130101; Y10T 442/674 20150401; D04H 1/64 20130101 |
Class at
Publication: |
442/180 ;
442/327; 442/394 |
International
Class: |
B32B 17/02 20060101
B32B017/02; D04H 13/00 20060101 D04H013/00 |
Claims
1. A permeable, coated, fibrous, nonwoven mat made by the process
of passing the nonwoven mat over the surface of a binder or coating
slurry to touch the bottom side of the mat sufficiently to fully
wet the glass mat, and immersing the mat in a slurry to fully
saturate the mat with the slurry material.
2. The nonwoven mat of claim 1, wherein the nonwoven mat has been
dried with infrared heaters, or other heating device such as
microwave, electromagnetic radiation.
3. The nonwoven mat of claim 2, wherein the drying of the nonwoven
mat is completed in an oven.
4. The nonwoven mat of claim 1, wherein the mat is immersed in the
slurry at least two times.
5. The nonwoven mat of claim 1, wherein a blade or rotating roll
set is used to remove excessive slurry to a desired level.
6-13. (canceled)
14. A laminate comprised of a first layer and a second layer, with
the second layer comprising the nonwoven mat of claim 1.
15. The laminate of claim 14, wherein the first layer is gypsum
board.
16. The laminate of claim 14, wherein the first layer is a polyiso
board.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a permeable glass mat and a
method of preparation therefor. More specifically, the porosity of
the glass mat from fully sealed to highly open can be controlled by
employing the method of the present invention.
[0003] 2. Description of the Related Art
[0004] Fibrous non-woven mats are often formed into a wet mat from
an aqueous dispersion of fibers such as glass and/or synthetic
organic fibers. The dispersion can include other fibers such as
cellulose fibers, ceramic fibers, etc. and can also include
particles of inorganic material and/or plastics. Usually a solution
of urea formaldehyde resin, usually modified with a thermoplastic
polymer, or one of many other known resin binders is applied to the
wet non-woven web of fibers and then, after removing excess binder
and water, the binded web is dried and heated further to cure the
urea formaldehyde resin or other resin binder to form a non-woven
mat product. Typical processes are disclosed in U.S. Pat. No.
7,138,346 , the disclosure of which is hereby incorporated herein
by reference.
[0005] In prior coating methods, often a raw glass mat enters a
coating station at a level lower than the top of an application
roll. The direction of travel of the glass mat is parallel to a
machine direction. The application roll is driven to rotate about
its axis and dip into a coating pan. The coating pan is filled with
a coating mix up to a level that is sufficient for the application
roll to pull an adequate amount of coating to the top of the
application roll. The speed of rotation of the application roll is
adjusted to get adequate amounts of coating mix up into the glass
mat as the glass mat is conveyed. The glass mat can extend around
the application roll to the degree desired. A scraper blade is used
to scrape off excess coating, which falls preferably back into the
coating pan. The coated mat then proceeds into a dryer section.
[0006] The history of gypsum board development has passed many
milestones, many of these milestones being related to the surfaces,
or facers, covering the broad surface of a gypsum board. In almost
all cases, the subject of a facer stability was an issue. Also the
facers have had to resist weathering as well as retaining constant
dimensions. Mildew and mold have been a problem with the original
multi-ply paper facers used on gypsum board. Unfortunately, the
paper facers also might not allow water vapor to escape. Yet the
escape of water vapor is essential in curing the gypsum. While
these paper facers have been modified with chemicals to improve
their properties, most of the gypsum board progress and success has
come by changing from paper facers to fiberglass mat facers.
[0007] The entire scope of manufacturing different facer materials
for building products is extensive, encompassing both fields of
gypsum board fiberglass facers and thermosetting polyiso foam
insulation board facers. In recent years, many facer-related
methods and products thereof have been taught in various
publications, including numerous United States patents.
[0008] Coating processes often fail to permit close control of the
porosity of a glass mat. This can be important, particularly with a
heavy solid coating mix, and for gypsum facers. As mentioned above,
the escape of water vapor is essential in curing/drying gypsum. The
key is to control the porosity of the coated facer mat so that the
coating is protective, yet porous enough to allow the water vapor
to escape during heating.
[0009] It is an objective of the present invention to provide such
a process for coating glass mats, with coatings having a wide range
of solid content, in order to control the porosity of the mat.
SUMMARY OF THE INVENTION
[0010] Accordingly, provided by the present invention is a
permeable, coated, fibrous non-woven mat made by the process of
first passing the non-woven mat over the surface of a binder or
costing slurry to touch the bottom side of the mat sufficiently to
fully wet the glass mat. After the wetting step, the mat is then
immersed in the slurry to fully saturate the mat with the slurry
material. Also provided is the process for preparing the coated
non-woven mat involving the step of first passing the non-woven mat
over the surface of a binder of coating slurry to touch the bottom
side of the mat sufficiently to fully wet the glass mat, followed
by the step of then immersing the mat in the slurry to fully
saturate the mat with the slurry material.
[0011] Among other factors, it has been found that the present
process of first touching the bottom side of the mat to fully wet
the glass mat followed by immersion in the slurry permits one to
prepare a non-woven mat, preferably a glass mat, with a controlled
porosity. The porosity can be controlled by controlling the solid
content of the slurry, introducing foam into a slurry, and/or
controlling blade pressure to remove excessive slurry at a desired
level.
[0012] In a preferred embodiment, a second impregnation or
saturation of the mat can take place should additional coating be
desired.
BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS
[0013] FIG. 1 depicts a coating process of the present invention
yielding a first impregnation.
[0014] FIG. 2 depicts an optimal second impregnation.
DETAILED DESCRIPTION OF THE INVENTION
[0015] For making a glass mat facer in different applications, the
coating is always applied on the glass mat to fully or partially
seal off the surface. In the present invention, the method
comprises impregnating a glass mat in a slurry containing solids.
The viscosity is controlled in making the saturated glass mat.
[0016] Referring to the figures of the drawing, in FIG. 1, the
glass mat 1 passes over the surface of a solid slurry 2 to pre-wet
the glass mat by touching the glass mat on the bottom side. When
the slurry impregnates the glass mat 1 from the bottom side of the
glass mat, air in the glass mat will be pushed up and the slurry
will fully wet the glass mat. Then pre-wet glass mat goes into the
slurry 3 to get further saturated. The saturated glass mat 4 can
the be dried by passing the mat by IR heaters 5. Other heating
devices such as microwave electromagnetic radiation can also be
used. If a higher weight of coating or lower porosity is required,
a second impregnation can be made as shown in FIG. 2. Blades 6
and/or a rotating roll set 7 can be used to remove excessive
slurry, or to simply control the slurry to a desired level.
[0017] In FIG. 1, slurry 2 can be different from slurry 3 in terms
of solid content and ingredients. The solid content of slurry can
be much lower than slurry 3 or just water containing a wetting
agent for wetting purposes or other conventional additives. The
ingredients of slurry 2 may be formulated differently from slurry
3, which results in two layers. For low cost with the same
performance, one can use a less expensive formulation in slurry 2
and better formulation in slurry 3. For special performance, each
slurry may introduce an individual feature for better combination
results such as color effect, smoothness, flexibility, anti-flame,
anti-mold, anti-static, waterproof, printability and paintability,
etc.
[0018] In a conventional coating process, the moisture content of a
mat would dramatically affect coating quality due to inconsistent
changes in coating viscosity as a result of moisture intake by the
mat. Particularly, a high viscose coating formulation such as a
high solid coating may encounter unemployable difficulty due to
moisture change at the interface of the mat and coating. With the
present pre-wet process, the mat will have an equilibrium moisture
content before immersion into slurry 3. It will lead to great
consistency in the process and a precisely controlled saturated
weight and porosity.
[0019] A coating is generally pushed from one surface into a mat in
a conventional coating process. The coating penetrated through the
mat is loosely packed in the mat. The tensile improvement of a
coated mat compared to a bare mat is in a limited range. With the
pre-wet and saturation process described herein, solid with binder
is able to cover tightly on the glass fiber surface. A higher
bonding strength of solid composite on the glass surface will
provide for more improved tensile strength of the saturated mat
compared to a coated mat.
[0020] With the present invention, the resistance on the mat used
by a passing blade or a rotating roll set can be lower, which will
allow a faster production line speed for higher productivity.
[0021] In FIG. 2 the impregnated glass mat 10 is immersed into a
container of slurry 11 to prepare a further saturated mat 12. The
saturated glass mat 12 then goes 13 into an oven for further
drying. Blades 15 and/or a rotating roll set 16 can be used to
remove excessive slurry.
[0022] The porosity of the saturated glass mat can be controlled
from fully sealed to highly opened (up to 200 CFM). The porosity is
controlled in the following ways: [0023] a. Control solid content
of slurry while remaining viscosity at workable range. [0024] b.
Introducing foam by adding foaming former and/or foam stabilizer
and mixing or through a foam-generator. [0025] c. Adding defoamer
to the formulation to achieve maximum slurry density for a tight
seal with minimum saturated weight. [0026] d. Control blade and/or
rotating roll pressure to remove excessive slurry at a desired
level.
[0027] The present process allows one to achieve a fully saturated
glass mat with controlled porosity so that it can be successfully
used as a facer for gypsum board. The coated glass mat can also be
used as a facer in other building materials. The porosity is
controlled at high consistency with reduced scrap rate. The
saturated mat has improved tensile strength. The process also finds
unique applicability in a high solid coating for a glass mat, such
as with an alkali metal silicate. Such a coated glass mat is
described in co-owned patent application [JM 7663], which is hereby
incorporated by reference.
[0028] Although the present invention has been described in
connection with preferred embodiments thereof, it will be
appreciated by those skilled in the art that additions, deletions,
modifications, and substitutions not specifically described may be
made without departing from the spirit and scope of the invention
as defined in the appended claims.
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