A Smart Guide to PVC Backed Modular Carpet and Vinyl Flooring
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This article is an update from Volume 21 dated September 2009 of the Commercial Flooring Report. It also relates to Luxury Vinyl Tile and Plank and other flooring materials that contain PVC or plasticizers. Because plasticizer migration has become a larger issue due to the growth of vinyl tile it is important for you to know about this condition and how to recognize it.
Modular Carpet – also known as carpet tile – is probably the least difficult soft flooring product to actually handle and install. That being said, the chemistries involved in most of the modular vinyl carpet backing systems that are in general use today can create serious and occasionally catastrophic issues that WILL land squarely on the shoulders of the flooring contractor if the correct steps have not been taken. Vari-ous aspects of this issue have been dealt with in several articles and publications.
In this article, I intend to go into detail regarding the chemistry involved in the manufacture of PVC modu-lar carpet backings and some of the downstream issues that can be created. The same is true for vinyl tile flooring material that is in use today. Knowing and understanding this chemistry will hopefully rein-force the need for caution when dealing with products that utilize PVC chemistry and make you smarter.
First and foremost, PVC is a superb backing for modular carpets and vinyl flooring material. This is true so long as the component parts of the PVC compound are properly manufactured AND the compound itself is correctly handled through the various manufacturing processes involved in creating the carpet web from which the modular carpet or vinyl flooring tile will be cut AND the final product is properly han-dled during the installation process. Wait a minute – How in the world am I, as a flooring contractor, ar-chitect, designer, general contractor, dealer, distributor or specifier supposed to know about any of this stuff?
Polyvinyl chloride abbreviated as “PVC” is a hard brittle white plastic in its pure form. It was discovered back in the mid 1800’s but was too brittle and unworkable to be commercially viable. In 1926, B.F. Goodrich discovered a way to make the material softer using additives – known as plasticizers. The ad-dition of these additives made the plastic extremely useful for a number of applications. When the term “PVC” is used in this article, it means a mixture of the hard brittle PVC polymer – usually ground to a very fine particle size – with a plasticizer to form what is called a “plastisol”. This plastisol generally has the consistency of toothpaste and can be pumped and manipulated through a manufacturing process with minimal difficulty. This plastisol also has the unique property that it can sit for long periods of time without drying out or becoming unworkable which makes it very friendly to the manufacturing process. When heated to high temperature – on the order of 380 degree F – this plastisol undergoes a phase change or fusion from liquid to solid and becomes the material we have all seen and handled when PVC backed flooring products are installed.
PLEASE NOTE THAT PLASTICIZER IS MECHANICALLY MIXED WITH THE PVC POLYMER TO FORM THE PLASTISOL. THERE IS NO CHEMICAL REACTION BETWEEN THE TWO. WHEN THIS MIX-TURE IS CURED VIA HEATING, SOME OF THE PLASTICIZER IS DRIVEN OUT WHICH RESTORES A PORTION OF THE ORIGINAL RIGIDITY OF THE PVC POLYMER AND GIVES THE FLEXIBLE WORKABLE PVC BACKING THAT IS A FAMILIAR PART OF THE FLOORING CONTRACTORS EXPERIENCE. THERE ALWAYS RE-MAINS A CERTAIN LEVEL OF “FREE” PLASTICIZER IN THIS BACKING. THIS “FREE” PLASTICIZER WILL BE SLOWLY RE-LEASED FROM THE BACKING THROUGHOUT THE LIFE OF THE PRODUCT. THIS RELEASE IS THE PHENOMENA KNOWN AS “PLASTICIZER MIGRATION”
PVC is an inherently unstable material. A pure homogeneous PVC film will grow and shrink with temperature and humidity changes. All PVC films change dimension over time as the various components that make up the compound seek equilibrium with the environment through the migration process noted above. To serve as a viable modular carpet or vinyl flooring backing, PVC films must be mechanically stabi-lized usually by the incorporation of multiple layers of a fiberglass fleece in carpet tile or a stabilizing layer in vinyl floor tile.
Essentially all plasticizers used in the manufacture of PVC backed flooring fall under the general chemical family known as “phthalates”. Some work is also being done on the use of epoxidized vegeta-ble oils as a substitute for phthalate based plasticiz-ers by some manufactur-ers. For purposes of safe-ty, always assume that the PVC backed material you are working with has phthalate type plasticizer.
Plasticizers are manufactured by reacting with a chemical known as phthalic anhydride with various organic alcohols. The reason that the installation contractor or anyone else involved or associated with the installation of these type flooring products should even be concerned with this is that – under very special conditions – this reaction can be reversed through a process known as alkaline hydrolysis. This is just a fancy way of saying that the material can be broken down by the ac-tion of water in a high pH environment. This can happen when PVC backed material is installed over a concrete slab that is emitting high levels of water vapor. There are also instances where this breakdown has happened due to issues within the PVC backing itself even when the PVC backed flooring material is installed over a perfectly acceptable floor. It is extremely important for the contractor to fully understand and rigorously document that the sub floor meets or exceeds ALL of the requirements of the manufacturer. In a typical situation where PVC backed flooring is installed over an out of specification sub floor, the emitted vapor may condense to liquid water under the PVC backed carpet– usually with a pH of about 12 or 12.5 which is about the internal pH of concrete itself.
Inevitably, this high pH condition comes in contact with the plas-ticizer that is continually diffusing out of the cured PVC plastisol that serves as the backing. What hap-pens is that the high alkalinity acts as a catalyst for the hydrolysis reaction and the plasticizer breaks down into its component parts.
This in itself would not be a problem except for the fact that the alcohols liberated by this breakdown have an EXTREMELY pungent odor most often smelling like a new plastic shower curtain or Play Doh. This odor can be so objectionable that it has caused buildings to be evacuated for months while the contaminated slab is either cleaned or removed and replaced. Remediation of this type of issue can result in contentious lawsuits and the dollars are HUGE.
DO YOU HEAR THE CASH REGISTER YET? GUESS WHO GETS BLAMED FOR THIS? YOU GOT IT – THE INSTALLATION CONTRACTOR.
This is why it is doubly important to dot the “I’s” and cross the “T’s” when it comes to vapor emission rates, In situ RH values and the surface pH of the concrete when you are working with PVC backed material. And, as we mentioned previously, this con-dition can also be inherent in the material itself.
This plasticizer migration is also the reason that it is imperative that the installation contractor and all parties involved KNOW what is being removed from the floor and what type of adhesive will be exposed to the potentially damaging action of plas-ticizer. Plasticizer is basically an organic solvent. Over time it will soften and begin to liquefy the ex-isting adhesive. The very worst situation is where there is exposed asphaltic adhesive such as “cut back”. Plasticizer literally returns the “cut back” to the consistency it had when it came from the pail. Once this happens it is inevitable that this nasty, gooey, black “stuff” works it way to the joints and seams and wicks to the surface of the flooring ma-terial. With latex based general purpose adhe-sives, this effect still happens but is not so dra-matic. As a general rule, the softer and stickier the exposed general purpose film is, the more likely it is to reach a degree of emulsification that allows it to wick up between the seams or joints in the floor-ing tiles. Remediation of this type of problem can easily reach 10 to 15 dollars per square FOOT.
WAIT – THERE GOES THE CASH REGISTER AGAIN AND AGAIN IT IS THE INSTALLATION CONTRACTOR THAT WILL BE BLAMED UN-LESS THEY ARE SMART.
REGARDLESS OF THE TYPE OF ADHESIVE EXPOSED, GET DETAILED PREPARATION GUIDELINES FROM THE MANUFACTURER OF THE FLOORING MATERIAL IN WRITING. IF THE MANUFACTURER IS RELUCTANT TO PUT GUIDELINES IN WRITING – DON’T INSTALL THE FLOOR.
Everyone in the chain of a project should know and use this information. If the flooring contractor tells the general contractor he thinks there’s going to be a problem or the potential for a problem exists every-body needs to heed his advice. Thinking nothing will happen is a very dangerous risk that can result in untold expenses to fix the problem. If a furnished facility has to be torn apart you can multiply the loss related to having to replace the flooring and remediate the substrate by at least a factor of 4. Do you re-ally want to spend or be liable for upwards of $100.00 a square foot to correct something that could have been prevented?
If you have questions or we can help you with a problem or better yet, help you to prevent having a problem call us. We can help keep you out of trouble with your flooring concerns or let you know why you have them and who’s at fault if you do. Let’s keep the money in your pocket, the flooring out of the landfill and the end user in business. That’s the essence of being green. You don’t want to experience this kind of pain or contribute to this waste of resources. We can also test questionable flooring prod-ucts for you to determine what may be wrong with them – certainly in the case of plasticizer migration as it relates to this issue.
THE MODULAR CARPET MARKET: Facts You Should Know
- Highest Growth Rate of Commercial Carpet material
- Key Element of the Systems Furniture Driven Office Market – Allows Carpet to be Replaced with no Disruption of Operation
- Unlimited Design Flexibility while Maintaining Ease of Installation
- Lower Waste Factors
- High Visibility of Major Installations
- Ease of Installation – transportation, handling, application, speed
- About 60% of Commercial Carpet is Modular Carpet (Floor Covering Weekly July 2018)
- Fastest growing segment of the commercial textile floor covering industry
- It is the most highly engineered textile floor covering product
- The highest performing textile floor covering product
LUXURY VINYL TILE AND PLANK: Facts You Should Know
The fastest growing segment of the flooring market. The product category is emerging so rapidly, and the product introductions are continually morphing that’s it’s almost impossible to keep up with. There are so many sources that you can’t know how they are all making the product.
The price of the product is always a factor and the lower it goes the more often problems of component and product stability and performance will be at issue. Everybody and his brother wants a piece of this market and there are a lot of people selling the product that actually know very little about it.
Article by Sim Crisler – Vice President and Lew Migliore – President LGMTCS and Associates