Thursday, November 11, 2010

Raw Materials for Siding

The quality you’ve come to expect from CertainTeed vinyl siding
and accessories is built in at the factory. From the time raw
materials are manufactured until finished product is shipped to
our customers, we control, adjust, inspect, and test throughout
every step of the manufacturing process. As part of on-going
quality assurance, we work with all our suppliers to develop tight
specifications and test for their consistency. The result is a line of
vinyl building products you can count on for superb appearance,
durability, and ease of installation—every time.
All siding is not created equal, and raw materials significantly
contribute to their differences. Though siding is referred to
simply as “vinyl,” CertainTeed vinyl siding is actually a precise
blend of carefully tested and controlled materials, all of which
contribute to its performance, durability, and appearance.
Polyvinyl Chloride
Polyvinyl chloride resin gives vinyl siding its name. PVC, which
starts as a powder, is a thermoplastic, which means that when it
is exposed to high temperatures in the manufacturing process,
the compound can be shaped, embossed, and formed. Eighty
percent of the weight of siding is PVC resin. The remaining 20
percent is the critical micro-ingredients that impart distinctive
color, opacity, gloss, texture, impact resistance, flexibility, and
durability to CertainTeed vinyl siding and accessories.
CertainTeed manufactures its own Certavin™ resin at its Lake
Charles, Louisiana, polymer plant. CertainTeed is one of the few
siding manufacturers to produce its own PVC resin, allowing us
to control the quality of this critical ingredient to our own
exacting specifications.
The most recent addition to CertainTeed’s extensive line of vinyl
building products, Cedar Impressions® Perfection and Half-
Round Shingles and Rough-Split Shakes are manufactured from
a specially blended polypropylene copolymer. This copolymer
capitalizes on the rigidity, weatherability, and processing
properties of polypropylene and other micro-ingredients.
Unlike our PVC siding, which is extruded, polypropylene Cedar
Impressions® is injection molded into its authentic cedar
shingle patterns.
ASA/AES are polymer alloys used specifically because
they impart particular performance characteristics to
siding. ASA/AES forms the capstock—protective surface—
for CertainTeed premium colors. Darker colors are harder to
protect against “fading” than lighter colors. In fact, unprotected
dark colors don’t fade, they oxidize, and they lose their rich
appearance as the white products of oxidation build up on the
surface of the siding. ASA/AES is extremely stable. They resists
oxidation and, hence, maintain their rich, dark hues.
While resin constitutes the bulk of the raw material in
vinyl siding, CertainTeed’s Certavin™ resin includes various
micro-ingredients that give siding its texture, low gloss, and
color and help process the raw materials. Following is a
description of those micro-ingredients and the role they play.
CertainTeed Vinyl Siding Master Craftsman Education & Development Program
4. Raw Materials
This chapter contains a short discussion of the raw materials
that are used to manufacture CertainTeed siding:
• Polypropylene
• Micro-ingredients
• Processing aids
Color Technology
All colors—or pigments, as they are sometimes called—are
carefully manufactured to meet our precise specifications.
We select and test all our pigments to verify that they are stable
and have excellent weathering properties, even without the
protectants (like TiO2 and stabilizers) that are added to PVC
compound. To verify batch-to-batch and run-to-run consistency,
spectrophotometers carefully measure color in every lot of
pigment. This rigorous quality control is at the heart of
CertainTeed’s PermaColor™ process and the rich, durable
colors of our siding and accessories.
Titanium dioxide is a critical additive in vinyl siding because it
protects PVC from potentially harmful UV rays. It makes siding
and vinyl accessories opaque and acts to prevent the sun from
degrading the resin, which could become cracked and brittle.
Typically, manufacturers of low cost vinyl siding use less TiO2,
because this additive is expensive and unsuspecting consumers
will not notice the weathering for a few years.
Calcium Stearate
CertainTeed uses only fused granular calcium stearate.
It helps the various ingredients in the PVC compound blend
into a uniform, stable dispersion and aids in the manufacturing
process. Its use particularly improves the fusion of the PVC
compound and produces a smooth, uniform finish that
resists cracking.
Waxes prevent the PVC compound from sticking to the metal
surfaces in the extrusion process. Wax also affects the gloss on
the finished product, so it is always used in precise amounts to
ensure consistent, reproducible finishes from batch to batch.
Impact Modifiers
Impact modifiers do just that. They make vinyl siding more
resistant to the dings and dents that routinely occur on the wall
and during and after installation. Carefully selected and blended
impact modifiers help CertainTeed vinyl siding withstand most
hail storms as well as normal installation and use.
Acrylic Processing Aids
The acrylic processing aids used in CertainTeed siding have
been developed specifically to help in manufacturing. They
produce a uniformly thick siding that is strong and durable.
Stabilizers are used to protect the PVC compound from
degrading as it is heated and subjected to pressure. This keeps
the plastic ductile. Also, additional UV stabilizers protect the
color from oxidizing and fading.
CertainTeed Vinyl Siding Master Craftsman Education & Development Program
• CertainTeed is able to control the quality of the PVC used in
its vinyl siding because it manufactures its own resin. All
raw materials are tested and controlled through every step
of the manufacturing process.
• To ensure quality and batch-to-batch consistency, the
pigments that give siding its color are held to very tight
specifications. TiO2, which protects against UV rays, is added
during the manufacturing process to protect the color and
reduce fading in siding.
• Impact modifiers help CertainTeed siding withstand
most hail storms and normal installation and use.
• Polypropylene copolymer can be processed into a
rigid, weatherable siding product. Using a process
called injection molding, CertainTeed processes
polypropylene into Cedar Impressions® Perfection
and Half-Round Shingles and Rough-Split Shakes.

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