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Fully vulcanized EPDM/PP TPV developments in automotive, building and construction materials. (Tech Service)(Cover Story).

Automotive weatherseals are undergoing materials and processing shifts from thermoset A polymer-based liquid or powder that becomes solid when heated, placed under pressure, treated with a chemical or via radiation. The curing process creates a chemical bond that, unlike a thermoplastic, prevents the material from being remelted. See thermoplastic.  elastomer elastomer (ĭlăs`təmər), substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic rubbers and rubberlike plastics from natural rubber.  compounds like ethylene-propylene-diene monomer monomer (mŏn`əmər): see polymer.

Molecule of any of a class of mostly organic compounds that can react with other molecules of the same or other compounds to form very large molecules (polymers).
 (EPDM EPDM Ethylene-Propylene-Diene-Monomer
EPDM Enterprise Product Data Management
EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components)
EPDM Engineering Product Data Management
)-based products to EPDM/PP-based thermoplastic A polymer material that turns to liquid when heated and becomes solid when cooled. There are more than 40 types of thermoplastics, including acrylic, polypropylene, polycarbonate and polyethylene.  vulcanizates (TPVs). EPDM thermoset compounds traditionally are used in weatherseal applications. Going forward, trends indicate that TPVs are gaining momentum, are being applied successfully in building and construction weatherseal applications, and now, in the automotive industry The automotive industry is the industry involved in the design, development, manufacture, marketing, and sale of motor vehicles. In 2006, more than 69 million motor vehicles, including cars and commercial vehicles were produced worldwide.  as well. Historically, the evolution of automotive weatherseals materials has been:

Flocked cloth [right arrow] latex [right arrow] SBR SBR - Spectral Band Replication  [right arrow] EPDM [right arrow] TPV TPV Temporary Protection Visa (Australia)
TPV Terminal Punto Venta
TPV Third-Party Verification
TPV Thermophotovoltaic
TPV Thermoplastic Vulcanizate (thermoplastic elastomer)
TPV Total Payment Volume

The key reasons for the latest TPV trends are:

* Lower part fabrication fabrication (fab´rikā´shn),
n the construction or making of a restoration.

* 100% recyclability in areas where conventional materials have displayed shortfalls;

* design flexibility (possibility to combine with other thermoplastic materials thermoplastic materials

materials used in making casts for broken limbs. Malleable when warmed in hot water or heated with a hairdrier, very quick setting and very strong, e.g. Hexcelite.
 and elimination of metal inserts);

* weight reduction;

* aesthetics (going beyond "Model T" black and diversifying TPVs by adding color to the seals).

The mechanical properties, benefits, efficiencies and processing solutions of TPVs will be discussed, focusing on weatherseals for automotive, building and construction use. In these segments, applications are diverse and range from: glass run channels, hood-to-cowl seals, hood-to-radiator seals, belt line seals, roof gutter seals and glass encapsulation (1) In object technology, the creation of self-contained modules that contain both the data and the processing. See object-oriented programming.

(2) The transmission of one network protocol within another.
 applications. Presently, most static and semi-dynamic seals are strong candidates for EPDM-based TPVs. The benefits of switching to TPVs will be explored, including cost savings, processing ease, fulfilling "green" recycling goals, offering design flexibility, weight reduction and meeting aesthetic goals.

Initially, this article will outline improvements made with TPVs which address some of the present constraints found in the automotive sealing systems segment. Then, the advantages that this thermoplastic material offers will be detailed. And finally, a convincing business case history presenting bottom line cost savings of the TPV systems versus more traditional systems will be presented.

Lifting present TPV constraints

In the ongoing search to replace some thermoset rubber materials in weatherseal applications, TPVs are being used in a growing number of industries and applications (including automotive under-the-hood rubber components). Yet, while TPVs have successfully displaced PVC PVC: see polyvinyl chloride.
 in full polyvinyl chloride

Synthetic resin, an organic polymer made by treating vinyl chloride monomers with a peroxide.
, EPDM and poly-chloroprene rubbers, the physical properties of the current crop of commercially available TPVs have not yet achieved their full potential in the marketplace. Recent innovations in 2001 have made strides to drive TPV performance to new levels, while addressing previous limitations. TRS See traffic engineering methods.

TRS - term rewriting system
 believes they have made significant advancements with their 1000 series TPV product line to improve both mechanical properties and fogging resistance, addressing the shortfalls with a patent pending technology.

Improved mechanical properties

As compared to low hardness (durometer 55A to 75A) compounds, EPDM thermoset compounds typically have exhibited higher tensile and tear strengths than TPV compounds. Recent advancements in TPV technology have made it possible to show improvements in the mechanical strength in the durometer 40A to 50D hardness ranges.

Table 1 outlines improvements in tensile strength tensile strength

Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its
, showing gains of at least 10% in low hardness grades. In addition, significant improvements in tear strength are shown (approximately 30%). Tear strength improvements represent a major advance for TPV weatherseals. Higher tear strength helps the handling phase of the total fabrication process, and in overall seal durability.

Fogging resolved

One of the complications in using TPVs for weatherseal applications is the fogging that can occur on clear glass due to the process oil that leaches out of the compound. Additionally, and specific to the automobile marketplace, fogging is an issue for soft-touch interior components like grips, cup holders, handles, bin liners and shift lever seals applications. Consumers and manufacturers both are dissatisfied with seals that contribute to fog on the glass. The 1000 series general-purpose TRS TPVs use a proprietary formula technology that resists oil migration. Other industry manufacturers have developed solutions to this problem in their specialty grade product lines. This year, all of our low hardness TRS TPV compounds offer the low-fog benefit to users, regardless of grade or formulations. Latest tests indicate that these new grades of TPVs yield a weight loss as low as 1.2 [+ or -] 0.2 milligrams at 100 [degrees] C for 16 hours as per the SAE 1756 gravimetric gravimetric /grav·i·met·ric/ (grav?i-me´trik) pertaining to measurement by weight; performed by weight, as a gravimetric method of drug assay.

 method. The weight loss is roughly half that which traditional general purpose TPVs experience.

In summary, the latest TPVs provide greater flexibility to manufacturers than ever before. The greatest challenge to production is cost; the low friction technology benefit of the latest TPV compounds competes with very expensive flocking and coating technologies used in thermoset systems.

Low friction surface technology

Weatherseals such as glass run channels and belt line seals are designed for noise damping damping

In physics, the restraint of vibratory motion, such as mechanical oscillations, noise, and alternating electric currents, by dissipating energy. Unless a child keeps pumping a swing, the back-and-forth motion decreases; damping by the air's friction opposes the
 and to provide sealing against air, dust and water. Characteristically, seals require a low friction surface in areas where the seal meets the door glass. The reason for the low friction surface is to provide resistance against wear. In the last few years, a coextruded TPV durometer 75A glass run channel with a TPV 50D durometer slip coat has been used. For stringent wear resistance requirements, it has been determined that a TPV 50D durometer is inadequate. Recent developments (patent pending) have determined that a high density moisture curable cur·a·ble
Capable of being cured or healed.
 polyethylene - like XL-HDPE NexCoat - is a cost-effective and viable alternative for superior wear resistance against the door glass. This technology is based on silane silane
 or silicon hydride

Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula SinH(2n + 2).
 pre-grafted onto the backbone of polyethylene. The pre-grafted resin is then mixed with a catalyst masterbatch just before processing. The compound is then extruded on a conventional thermoplastic extruder. This is a viable alternative to ultra high molecular weight polyethylene, which has exceptional wear resistance but cannot be easily coextruded using thermoplastic processing without sacrificing wear resistance. Surprisingly, XL-HDPE can be coextruded onto TPVs as a slip coat to provide exceptional results. Abrasion abrasion /abra·sion/ (ah-bra´zhun)
1. a rubbing or scraping off through unusual or abnormal action; see also planing.

2. a rubbed or scraped area on skin or mucous membrane.
 resistance testing based on GM9909P (General Motors) specifications yielded 10,330 cycles per 5 kg, where the minimum requirements are 10,000 cycles per 3 kg load. This also yields a coefficient of friction coefficient of friction
n. pl. coefficients of friction
The ratio of the force that maintains contact between an object and a surface and the frictional force that resists the motion of the object.
 (COF) of 0.3. Using this optimized process, a product can be manufactured with a COF in the range of 0.1 to 0.3, using a clean technology. In contrast, a 50D durometer TPV yields a COF of 0.6, thus inadequate wear resistance. Another benefit is that the scrap of the coextruded 75A durometer and the XL-HDPE slip coat can be reground and utilized, addressing recycling issues.


Also, our latest developments impart the benefits of reduced glare and a dry, non-greasy look and feel in a lightweight TPV compound. Of course, there is more to TPVs than low friction technology.

Adding up TPVs

Every manufacturing business is under pressure to keep their operation lean and as productive as possible. Nowhere is this truer than in the automotive business and construction markets. Generally, due to the high content of the pure EPDM in TPV-material EPDM/PP products, it is more expensive than traditional materials. The upside to using TPVs is that manufacturers see quantitative savings in the finished product; typically, the cost per part is reduced by 10-30% due to efficient thermoplastic processing, waste reduction and the ability to recycle waste materials. EPDM/PP based TPVs exhibit a two-phase morphology. The PP is the continuous phase component in the morphology, and the highly vulcanized rubber India rubber, vulcanized.
- Knight.

See also: Vulcanize
 particles (approximately 1 to 2 microns) constitute the dispersed phase Noun 1. dispersed phase - (of colloids) a substance in the colloidal state
dispersed particles

phase, form - (physical chemistry) a distinct state of matter in a system; matter that is identical in chemical composition and physical state and separated from
. Even though the concentration of rubber is much higher than the PP in TPVs, the PP provides ease of processing. Thus, TPVs are ideal for injection molding injection molding
A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold.
, blow molding and extrusion operations.

An all TPV glass run channel and belt line seal is the "best-fit" automotive weatherseal application. It benefits most from tremendous cost savings (30%) through the elimination of long cycle times for corner molding and complex traditional flocking processes. In addition to the cost savings, there is also an approximately 22% weight savings by using an all TPV seal.

A cost comparison chart is shown in table 2. This is where the "robber meets the road."


The latest generation of EPDM/PP fully vulcanized vul·ca·nize  
tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es
To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat
 TPVs is not restricted to "old materials paradigms." By directly addressing the needs of the marketplace, newly formulated TPV compounds deliver low fogging, higher tear strength, higher tensile strength and more environmentally friendly Environmentally friendly, also referred to as nature friendly, is a term used to refer to goods and services considered to inflict minimal harm on the environment.[1]  materials to aid in the goal of creating fully recyclable vehicles. Enhanced aesthetics and colorability, and UV resistance coupled with ease of processing position the latest TPV grades for expansion into other areas beyond secondary weatherseals for the automotive, building and construction markets. In the future, a trend of system integration like combining polycarbonate A category of plastic materials used to make a myriad of products, including CDs and CD-ROMs.  windows with an integrated TPV seal is a possibility.

Going forward, EPDM based TPVs are positioned to expand into the 500 km ton plus automotive weatherseal EPDM compound market. TPVs offer viable alternatives to markets that strive to overcome the limitations of thermoset rubber, while maintaining their benefits like cost, weight reduction and recyclability.
Table 1 -- mechanical properties

Property                Test       Units       Durom. 55A
                       method                TPV-   Nexprene
                       (ASTM)                 A      1055A

 gravity               D-792                 0.97     0.97
 strength              D-412        MPa      4.4      6.6
 ("X flow")            D-624        KN/m      19       31
 set (22 hrs.          D-395         %        27       27
 @ 70 [degrees] C)   (method B)

Property                   Durom. 64A          Durom. 73A
                        TPV-      Nexprene   TPV-   Nexprene
                         A         1064A      A      1075A

 gravity                0.97        0.97     0.97     0.97
 strength               6.9         7.6      8.5       10
 ("X flow")              25          35       28       47
 set (22 hrs.            31          32       35       35
 @ 70 [degrees] C)

Property                   Durom. 80A          Durom. 87A
                        TPV-      Nexprene   TPV-   Nexprene
                         A         1080A      A      1087A

 gravity                0.97        0.97     0.96     0.96
 strength                11         12.4     15.9     16.9
 ("X flow")              34          57       49       69
 set (22 hrs.            41          41       45       45
 @ 70 [degrees] C)

Note: TPV--A isa commercially available fully vulcanized TPV
Table 2

Cost                      All TPV glass    Traditional thermoset
                           run channel    EPDM compound + flocking

Rubber compounding              0                     5%
Extrusion                  10% (co-ex)       15% (vulcanizing)
Flocking                        0%                    6%
Cutting                   0% (in-line)                4%
Corner molding                 15%                   25%
Flash/Scrap                     1%                    5%
Total processing cost          26%                   60%

Raw material
Extrusion material             40%                   20%
Corner molding material         4%                    2%

Flocking material
Primer                          0%                    4%
Adhesive                        0%                    6%
Polyester fiber                 0%                    8%

Total raw material cost        44%                   40%
Total part cost                70%                  100%

Jonas Angus is president and CEO (1) (Chief Executive Officer) The highest individual in command of an organization. Typically the president of the company, the CEO reports to the Chairman of the Board.  of Thermoplastic Rubber Systems, a company he co-founded in 2000. He began his career at Polysar and moved to DSM 1. DSM - Data Structure Manager.

An object-oriented language by J.E. Rumbaugh and M.E. Loomis of GE, similar to C++. It is used in implementation of CAD/CAE software. DSM is written in DSM and C and produces C as output.
 when that company purchased the Sarlink business. He has also worked for Ticona.
COPYRIGHT 2001 Lippincott & Peto, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
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Comment:Fully vulcanized EPDM/PP TPV developments in automotive, building and construction materials. (Tech Service)(Cover Story).
Author:Angus, Jonas
Publication:Rubber World
Geographic Code:1USA
Date:Oct 1, 2001
Previous Article:New heat treating method for the curing of rubber profiles. (Process Machinery).
Next Article:New TPE bonding technology and various overmolding processes for TPV applications. (Cover Story).

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