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WO2002000420A1 - Mastic d'etancheification d'une cavite et son procede de fabrication - Google Patents

Mastic d'etancheification d'une cavite et son procede de fabrication Download PDF

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Publication number
WO2002000420A1
WO2002000420A1 PCT/US2001/008503 US0108503W WO0200420A1 WO 2002000420 A1 WO2002000420 A1 WO 2002000420A1 US 0108503 W US0108503 W US 0108503W WO 0200420 A1 WO0200420 A1 WO 0200420A1
Authority
WO
WIPO (PCT)
Prior art keywords
weight
sealant
eva
cavity
composition
Prior art date
Application number
PCT/US2001/008503
Other languages
English (en)
Inventor
Gerald Fitzgerald
Chin-Jui Chang
Paul Engel
Original Assignee
Sika Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sika Corporation filed Critical Sika Corporation
Priority to AU2001249232A priority Critical patent/AU2001249232A1/en
Publication of WO2002000420A1 publication Critical patent/WO2002000420A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D29/00—Superstructures, understructures, or sub-units thereof, characterised by the material thereof
    • B62D29/001—Superstructures, understructures, or sub-units thereof, characterised by the material thereof characterised by combining metal and synthetic material
    • B62D29/002—Superstructures, understructures, or sub-units thereof, characterised by the material thereof characterised by combining metal and synthetic material a foamable synthetic material or metal being added in situ
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/0065—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K3/00—Materials not provided for elsewhere
    • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2791/00—Shaping characteristics in general
    • B29C2791/001—Shaping in several steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2791/00—Shaping characteristics in general
    • B29C2791/004—Shaping under special conditions
    • B29C2791/006—Using vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/10—Forming by pressure difference, e.g. vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/22—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using layers or sheathings having a shape adapted to the shape of the article
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C08L25/08—Copolymers of styrene
    • C08L25/10—Copolymers of styrene with conjugated dienes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K2200/00—Chemical nature of materials in mouldable or extrudable form for sealing or packing joints or covers
    • C09K2200/06—Macromolecular organic compounds, e.g. prepolymers
    • C09K2200/0615—Macromolecular organic compounds, e.g. prepolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C09K2200/0622—Polyvinylalcohols, polyvinylacetates

Definitions

  • the present invention relates generally to thermally flowable expandable sealants and thermally flowable non-expandable sealants used to seal cavities in floor pans of motor vehicles. More particularly, the sealants are vacuum-formed from a thermoplastic composition in shapes and sizes corresponding to the respective cavities in which they will be utilized. Upon thermal activation, the sealant will flow and expand so as to fill the crevices and contours of the surfaces defining the cavity as well as to cover and block all openings.
  • the floor pan of a vehicle equipped with this option generally includes at least two cavities formed therein, with the cavities being at least partially defined by respective opposing side margins.
  • a so-called "seat striker" comprising an elongated bar or rod formed of a high-strength material (e.g., steel) extends between the opposing side margins.
  • the base of the removable seat includes protruding locking mechanisms in locations which correspond to the locations of the cavities on the floor pan. To install the seat, it is positioned above the floor pan cavities so that one locking mechanism is partially inserted into each cavity and latched to the seat striker, thus removably attaching the seat to the floor of the motor vehicle in a secure and stable manner.
  • the cavity did not include any type of seal.
  • moisture and contaminants were allowed to enter the vehicle via the cavity, often causing corrosion to parts of the vehicle.
  • the cavities allowed road noises to enter the vehicle, which is distracting and annoying to the vehicle occupants.
  • the instant invention overcomes these problems by broadly providing a sealant which effectively seals floor pan cavities without interfering with seat strikers or other mechanisms.
  • the sealant comprises a thermoplastic composition (e.g., an ethylene vinyl acetate-based composition preferably modified with an elastomer) which is formed into a size and shape corresponding to that of the cavity to be sealed.
  • a thermoplastic composition e.g., an ethylene vinyl acetate-based composition preferably modified with an elastomer
  • this is accomplished by vacuum molding a sheet of the thermoplastic composition to obtain the final sealant, although injection molding of the sealant can be utilized instead.
  • the sealant is positioned in the target cavity during manufacturing of the motor vehicle.
  • a striker rod is tangent to the floor pan and received within the cavity for securing a removable seat within the motor vehicle in cooperation with a locking mechanism on the base of the seat, hi such instances, it is preferable that the sealant include openings therethrough corresponding to the size, shape, and location of the striker rod so that the sealant will not interfere with normal operation of the rod.
  • the positioned sealant is held in place by gravity and subjected to the various stages of the manufacturing process. Because the sealant is formed of a composition having an activation temperature of at least about 250 °F, the sealant will not be affected by these manufacturing stages.
  • the sealant will be activated at a pre-determined, specific point in the manufacturing process (e.g., such as during the paint or powder bake stage) where the sealant will be exposed to an elevated temperature for a predetermined period, for example, above 325 °F for a period of about 20 minutes. Upon thermal exposure, the sealant will simultaneously flow under the force of gravity and may moderately expand into and against the cracks, crevices, corners, etc. of the structure defining the cavity. Additionally, due to the selection of the size and shape of the sealant, the material will flow over, and thus seal, all openings so as to prevent moisture, noise, and contaminants from entering the vehicle.
  • a pre-determined, specific point in the manufacturing process e.g., such as during the paint or powder bake stage
  • Fig. 2 is an end view of the sealer of Fig. 1;
  • Fig. 3 is a side view of the sealer of Fig. 1;
  • Fig. 4 is a plan view of the sealer of Fig. 1;
  • Fig. 5 is a vertical cross-sectional view taken along line 5 — 5 of the sealer depicted in Fig. 4
  • Fig. 6 is a perspective view of a floor pan cavity to be sealed with the inventive sealer
  • Fig. 7 is a plan view of the floor pan cavity of Fig. 6 having the inventive sealer of Fig. 1 disposed therein, after thermal exposure;
  • Fig. 8 is a graph depicting the viscosity vs. temperature profile of the runs described in Example 3.
  • Figs. 1-5 illustrate a preferred cavity sealant according to the invention.
  • the sealant 10 is a one-piece, flexible structure which is configured to correspond to the overall shape and size of the floor pan cavity in which it will be installed.
  • the illustrated sealant 10 comprises a substantially rectangular lip 14 having upper and lower surfaces 16, 18 and inner and outer peripheries 20, 22.
  • Sealant 10 further includes sidewalls 24a,b and endwalls 26a,b.
  • Sidewalls 24a,b include respective leftward sections 28a,b, respective midsections 30a,b, and respective rightward sections 32a,b.
  • Each of sections 28a,b, 30a,b, and 32a,b extend in a downwardly sloping direction from inner periphery 20 of lip 14.
  • Leftward sections 28a,b include upper sloping portions 34a,b and lower sloping portions 36a,b.
  • Upper sloping portions 34a,b slope downwardly from inner periphery 20 at a substantially constant angle to respective diagonal ridges 38a,b where lower sloping portions 36a,b begin, slightly offset from the path of slope of portions 34a,b in a direction towards the opposing sidewall 24a or 24b.
  • rightward sections 32a,b include corresponding upper sloping portions 40a,b, lower sloping portions 42a,b, and intermediate diagonal ridges
  • Midsections 30a,b have a substantially constant slope along their respective lengths to the point of intersection of midsections 30a,b with leftward sections 28a,b and rightward sections 32a,b.
  • Endwalls 26a,b includes respective upright walls 46a,b and respective angled walls 48a,b.
  • Upright walls 46a,b extend downwardly and substantially vertically from inner periphery 20 so that walls 46a,b are substantially parallel to one another.
  • Angled walls 48a,b slope downwardly from upright walls 46a,b in a direction towards the opposing endwall 26a or 26b.
  • endwalls 26a,b are joined with leftward sections 28a,b and with rightward sections 32a,b at respective rounded corners 50a-d.
  • Sealant 10 also includes a bottom portion 52.
  • Bottomportion 52 comprises first and second ends 54, 56 separated by an opening 58.
  • each of ends 54, 56 include respective lower, flat portions 60a,b and respective raised ledges 62a,b.
  • Ledges 62a,b comprise respective substantially horizontal, upper surfaces 64a,b and downwardly sloping bridges 66a,b.
  • ledges 62a,b include respective sloped walls 68a,b which extend downwardly from upper surfaces 64a,b and bridges 66a,b to join ledges 62a,b with flat portions 60a,b and angled walls 48a,b of endwalls 26a,b.
  • the sealant 10 is preferably vacuum-formed from a starting thermoplastic composition.
  • Vacuum molding is the preferred method (although inj ection molding is also acceptable and may be preferred in some applications) due to the ease of manufacturing and lower costs associated with vacuum forming.
  • the vacuum- forming process from about 150-225 g of the starting material is pressed into a sheet having a thickness of from about 1.5-2.5 mm, and preferably about 2.0 mm.
  • the press platens have a temperature of from about 140- 260 °F, and more preferably about 200 °F.
  • Pressing is preferably carried out for a time period of from about 10-60 seconds, and preferably about 20 seconds, at a pressure of from about 6-12 tons/ft 2 , and preferably about 10 tons/ft 2 .
  • the pressed sheet can either be formed into a sealant part immediately or can be stored for later use.
  • the pressed sheet is then placed over a mold having a cavity formed therein whose overall configuration is chosen according to the size and shape of the floor pan cavity in which the final sealant will ultimately be utilized.
  • the starting material is heated to a temperature above the softening point of the material (e.g., from about 140-260 °F, and preferably about 200 °F) while a vacuum of from about 6-12 psig, and preferably about 9 psig is applied to the mold.
  • a temperature above the softening point of the material e.g., from about 140-260 °F, and preferably about 200 °F
  • a vacuum of from about 6-12 psig, and preferably about 9 psig is applied to the mold.
  • the vacuum pulls it into and along the crevices and contours of the mold.
  • the molded material is then allowed to cool after which excess pieces are trimmed, and the final formed sealant removed from the mold.
  • thermoplastic material capable of being vacuum- formed can be utilized as the starting composition to form the inventive sealant 10.
  • the material should be chosen so that the final sealant 10 exhibits certain physical properties, with one of the most preferred properties being controlled flow upon thermal exposure. That is, the formed sealant must be flowable at the desired bake stage.
  • the sealant When heated to a temperature of about 325°F, the sealant should have a viscosity of from about2 x 10 4 - 1 x 10 7 cP, and preferably from about 9 x 10 4 - 8 x 10 6 cP.
  • the final sealant may also have a low percent expansion (i.e., less than about 250%, preferably from about 50-150%) when heated to a temperature of about 325 °F for about 30 minutes, wherein the percent expansion (as used herein) is defined as:
  • sealants which have the foregoing properties and controlled flow characteristics, and which expand only slightly upon heating, are preferably formed from a composition comprising a polymeric base which includes ethylene vinyl acetate (EVA) and an elastomer.
  • EVA ethylene vinyl acetate
  • the sealant composition should comprise from about
  • EVA ethylene glycol dimethacrylate copolymer
  • the chosen EVA preferably has a melt index of from about 1-150 dg/min., and preferably from about 3-50 dg/min. (at an extrusion pressure of 2.16 kg and temperature of 190°C as defined by ASTMD-1238).
  • the preferred EVA is from about 18-38% by weight vinyl acetate, and preferably from about 26-30% by weight vinyl acetate, based upon the total weight of EVA taken as 100%> by weight.
  • the sealant composition comprises a mixture of two EVA compounds, with the first EVA compound having an ASTM D- 1238 melt index of from about 1-150 dg/min., preferably from about 6-10 dg/min., and the second EVA compounds having an ASTM D-1238 melt index of from about 1-150 dg/min., preferably from about 1-5 dg/min.
  • the first EVA compound When two EVA compounds are included in the sealant composition, the first EVA compound should be present at a level of from about l-70%o by weight, and preferably from about 10-55%) by weight, and the second EVA compound should be present at a level of from about 1-65% by weight, and preferably from about 10-45% by weight, based upon the total weight of the sealant composition taken as 100% by weight.
  • Preferred first and second EVA compounds for use in this embodiment are Elvax ® 450 and Elvax ® 265, respectively (available from DuPont).
  • the elastomer utilized in the sealant composition is preferably a cross-linked rubber (either chemically or physically cross-linked) and preferably has a glass transition temperature of at least about -29 °C, preferably from about -40 °C to about -70 °C, and more preferably from about -50 °C to about -60 °C.
  • the rubber should be included in the composition at a level of from about 5-25% by weight, and preferably from about 10-20%> by weight, based upon the total weight of the sealant composition taken as 100% by weight.
  • Preferred rubbers include copolymers of styrene, butadiene, and ethylene.
  • Particularly preferred rubbers are styrene butadiene rubber (SBR) with a weight ratio of styrene to butadiene of from about 1:2.12 to about 1:4.39, and preferably from about 1:2.93 to about 1:3.58, and styrene ethylene butylene styrene rubber (SEBS) with a weight ratio of styrene to ethylene and butylene of from about 1:2.25 to about 1:2.65.
  • SBR styrene butadiene rubber
  • SEBS styrene ethylene butylene styrene rubber
  • the sealant composition can also include other compounds as necessary to control or modify the properties of the final sealant part.
  • the sealant composition can include a colorant such as carbon black or carbon black dispersed in EVA (preferably with a carbon black to EVA ratio of about 1:1).
  • the colorant should be present in the sealant composition at a level of up to about 2.0% by weight, and preferably from about 0.10-2.0%) by weight, based upon the total weight of the sealant composition taken as 100% by weight.
  • the sealant composition typically comprises from about 1- 70%) by weight filler, and more preferably from about 30-50%> by weight filler, based upon the total weight of the sealant composition taken as 100% by weight.
  • a wax can also be included in the sealant composition at a level of up to about 10% by weight wax, and preferably from about 2.5-7.5%) by weight wax, based upon the total weight of the sealant composition taken as 100% by weight.
  • Preferred waxes have a softening point of from about 70-130°C, and preferably from about 95-105 °C.
  • the sealant compositions further comprise from about 0.1-15% by weight, and preferably from about 2.5 -7.5 % by weight, of a tackifier which is preferably a hydrocarbon tackifying resin.
  • the softening point of the tackifier is preferably from about 45-125 °C, and more preferably from about 65-105 °C.
  • the sealant composition should also contain a blowing agent.
  • the blowing agent is preferably present in the composition at a level of up to about 2.0% by weight, and preferably from about 0.10-0.75% by weight, with diazocarbonamide being the most preferred blowing agent.
  • the sealant composition further comprises a system for activating the blowing agent.
  • One preferred such system includes zinc oxide, stearic acid, and urea. The preferred concentrations of the activation system components are set forth in Table A.
  • Percent by weight based upon the total weight of the sealant composition taken as 100% by weight.
  • SikaSeal 750 available from Sika Corporation, Michigan.
  • a sealant composition can be utilized which has controlled flow characteristics and essentially no expansion when heated to a temperature of about 325 °F for about 20 minutes. This is accomplished by eliminating the blowing agent from the formulation.
  • the polymer system of the composition is an EVA-based system and can optionally be modified with a rubber (such as SBR or other styrene-based copolymers and terpolymers) as discussed above.
  • a rubber such as SBR or other styrene-based copolymers and terpolymers
  • mineral fillers can be used to reduce flow and waxes can be utilized to induce flow and to facilitate wetting.
  • a tackifier is preferably included to improve adhesion to the various substrates.
  • the preferred sealant composition according to this embodiment is formulated according to Table B.
  • the EVA comprises from about 18-38% by weight vinyl acetate and preferably from about
  • c Such as carbon black dispersed in EVA with a weight ratio of carbon black to EVA of about 2:1.
  • d Preferably calcium carbonate, talc, and/or silica.
  • e Preferably with a softening point of from about 70- 130 °C, and more preferably from about 95- 105 ° C.
  • f Preferably a hydrocarbon tackifying resin.
  • the sealant composition is prepared in laboratory-scale by mixing all of the ingredients except the accelerator and blowing agent at elevated temperatures (e.g., at least about 200 °F, and preferably at least about 220 °F) until a substantially homogenous mixture is obtained. The mixture temperature is then lowered to about 150°F at which time the accelerator and blowing agent are added and mixing is continued. Once the mixture becomes homogeneous, the material is pressed into sheets, and the parts are then vacuum formed (Example 1 below provides a detailed description of this process).
  • elevated temperatures e.g., at least about 200 °F, and preferably at least about 220 °F
  • the sealant is compounded through a pelletization process.
  • This process involves feeding the ingredients of the formulation into a continuous compounder which mixes the ingredients and pelletizes the material.
  • Pellets can be prepared via strand pelletization or underwater pelletization processes. Pellets can be extruded into sheet stocks which can then be vacuum formed into the desired parts, hi addition, pellets can be injection molded directly into the desired parts.
  • Cavity 73 is defined by bottom surface 72, sidewalls 74a,b, and endwalls 76a,b.
  • sidewalls 74a,b include varying contours and angles which result in a complex surface.
  • Endwalls 76a,b include respective lips 80a and 80b (not shown) which extend downwardly from the floor plan 71.
  • the lip 80a,b cooperate with sidewalls 74a,b and bottom surface 72 to form openings 82a and 82b (not shown). If the cavity 73 is not properly sealed, openings 82a,b serve as a passageway for moisture, contaminants, noise, etc. to enter the motor vehicle from the outside.
  • Striker 84 further comprises a horizontal upper bar
  • the removable seat or chair includes a locking mechanism which is secured around bar 88 and thus to striker 84.
  • the sealant 10 is deposited into cavity 73 (preferably after E-coat bake and prior to the application of the powder primer coating), with seat striker 84 passing through opening 58 of sealant 10.
  • seat striker 84 passing through opening 58 of sealant 10.
  • an adhesive strip or layer to the underside of lip 14 (or to any other part of the sealant 10) in order to improve adherence of the sealant 10 to the floor pan 71.
  • any of a number of process or manufacturing steps may be carried out on the vehicle body prior to thermal exposure of the sealant 10 without affecting the ability of the sealant 10 to flow, sag, and may very moderately expand.
  • the activation temperature of the sealant 10 is reached, the sealant 10 begins to flow and, by virtue of gravity combined with expansion (in instances where the sealant 10 is formed of an expandable composition), is substantially directed into all crevices and contours formed by the structure that defines cavity 73. Referring to Fig. 7, it can be seen that, upon activation, the respective ledges
  • sealant 10 may expand somewhat (in instances where the sealant
  • the seal formed between the sealant and the floor pan surfaces should be sufficiently strong so that moisture is substantially prevented from penetrating the seal.
  • a top plate is secured to the upper portion of a floor pan having a cavity sealed according to the invention (after thermal activation). This assembly is then submerged in a water tank, and the pressure in the tank is varied sequentially as follows:
  • the pressure is increased to about 1 psig and held for about 2 minutes; (2) the pressure is increased to about 2 psig and held for about 2 minutes; and (3) the pressure is increased to about 3 psig and held for about 2 minutes.
  • sealant 10 has been depicted and described as having a very specific size and shape, it will be appreciated that this size and shape were as chosen to correspond to the size, shape, contours, etc. of cavity 73 as well as the locations of openings 82a,b. Thus, the size and shape of sealant 10 can be modified as desired, depending upon the cavity in which it will be utilized.
  • the sealant can be vacuum-formed from two starting pieces formed of different materials.
  • a composition can be applied to the sealant prior to thermal exposure in order to assist in maintaining the thickness of the sealant walls upon activation.
  • Such a chemical assist could include a composition that is coated or sprayed on the sealant as well as a material which is actually bonded (e.g., via pressure- sensitive adhesion) to the sealant.
  • a sigma blade mixer (BP Processing, USA) was used to prepare the sealant composition.
  • the mixer temperature was set to 220 °F, and styrene-butadiene rubber (SBR 1009), ethylene vinyl acetate polymer (Elvax ® 240), and carbon black filled ethylene vinyl acetate (B 22237 Black) were initially added to the mixer.
  • SBR 1009 styrene-butadiene rubber
  • Elvax ® 240 ethylene vinyl acetate polymer
  • B 22237 Black carbon black filled ethylene vinyl acetate
  • Zinc oxide, stearic acid, and hydrocarbon tackifying resin (Piccopale 100) were then added to the mixer and mixing was recommenced and continued until the mixture was homogenous. Finally, wax (Microsere 5999) was slowly added in small increments, and the mixture was mixed for approximately 15 minutes until the mixture was again homogenous. The material temperature was lowered to 150°F after which diazocarbonamide (Unicell D 1100) and urea (BIK-OT) were added, and the material was mixed until it was flux and uniform.
  • diazocarbonamide Unicell D 1100
  • urea urea
  • Part 2 The parts formed in Part 2 were tested. A mock cavity which very closely reflected the actual application was prepared. Specifically, application segments of the vehicle floor pan and rail were cut out in order to test the sealer. The floor pan was clamped to the rail so that the opening in the floor pan lined up with the rail cavity, thus providing an assembly comprising a floor pan segment forming a pocket over the rail at the seat anchor position. The previously formed part was placed on the assembly so that it fit snugly into the pocket. The entire assembly was then baked for 20 minutes at 325 °F in a forced air oven.
  • the process was repeated on other parts with a nominal bake of 15 minutes at 300 °F (underbake) and a maximum bake of 45 minutes at 375 °F (overbake). Multiple cavities were baked to ensure that the material sealed pockets having different depths and configurations.
  • the part was baked, it was visually examined. It is important that the part flow and seal the desired openings. At the same time the part must not flow so much that the material thins and subsequently tears. After a visual inspection, the part was tested for water leaks. Two tests were used to ensure the part sealed the cavity completely - a water leakage test and a water pressure test. In the water leakage test, water was poured into the opening or cavity. If any water leaked, the seal was deemed to be inadequate. If water did not leak, the part was deemed to adequately seal the opening. hi the water pressure test, the fixture was placed in, and secured to, a water tank.
  • a Percent by weight of ingredient based upon the total weight of all ingredients in the composition taken as 100% by weight.
  • CF a Specific Gravity with reference to water.
  • CF refers to cohesive failure meaning that the material itself failed rather than the adhesion between the material and the substrate.
  • a sigma blade mixer (BP Processing, USA) was used to prepare the sealant composition.
  • the mixer temperature was set at 220 °F, and styrene-ethylene-butylene- styrene block polymer (Kraton 1652), ethylene vinyl acetate polymer (Elvax ® 450), ethylene vinyl acetate polymer (Elvax ® 265), and carbon black filled ethylene vinyl acetate (B 22237 Black) were initially added to the mixer.
  • Mixing was commenced and continued until the mixture was homogeneous at which point the temperature of the mixture was at least 220°F.
  • the molded parts were prepared using the material prepared in Part 1 of this Example and following the procedures described in Part 2 of Example 1. The resulting parts were then tested as described in Part 3 of Example 1. The test results are set forth in Table 4. The viscosity of each part is depicted in Fig. 8, with the diamonds referring to Run 6, the squares referring to Run 7, and the inverted triangles referring to Run 8.
  • a Percent by weight of ingredient based upon the total weight of all ingredients in the composition taken as 100% by weight.
  • b Ethylene vinyl acetate grafted with maleic anhydride.
  • c Talc powder.
  • d ax. e Wax. f Tackifier.

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  • Medicinal Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Architecture (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Sealing Material Composition (AREA)

Abstract

L'invention porte sur un mastic (10) fluide à chaud servant à assurer l'étanchéité de cavités (73) de bacs de plancher de véhicules automobiles. Ledit mastic (10) est mis en forme sous vide à partir d'un matériau thermoplastique disposé dans un moule donnant une pièce de mastic (10) dont les dimensions et la forme correspondent à celles de la cavité (73) à rendre étanche. Le mastic (10) une fois formé est souple, présente une résistance élevée et une viscosité d'au moins environ 2 x 104 cP quand chauffé à une température d'environ 325 °F. Pour le mettre en oeuvre, on place le mastic (10) dans la cavité (73) à rendre étanche où il se maintient par gravité pendant les différentes étapes de la fabrication. Lors qu'il est soumis la chaleur (par exemple lors de la cuisson des poudres pendant le processus de fabrication d'une automobile), il commence à s'écouler sous l'effet de la gravité et, dans certaines exécutions, à se dilater modérément dans les différentes crevasses du bac (71) de plancher constituant la cavité (10) qui devient ainsi étanche.
PCT/US2001/008503 2000-06-26 2001-03-14 Mastic d'etancheification d'une cavite et son procede de fabrication WO2002000420A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001249232A AU2001249232A1 (en) 2000-06-26 2001-03-14 Cavity sealant and method of making the same

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US60340600A 2000-06-26 2000-06-26
US09/603,406 2000-06-26

Publications (1)

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WO2002000420A1 true WO2002000420A1 (fr) 2002-01-03

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8398086B2 (en) 2007-08-21 2013-03-19 Toyota Jidosha Kabushiki Kaisha Sealing element and sealing method including fusing the element
WO2014040913A1 (fr) * 2012-09-11 2014-03-20 Sika Technology Ag Agent moussant thermoplastique
WO2017036624A1 (fr) * 2015-09-02 2017-03-09 Sika Technology Ag Mousse expansible à la chaleur

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872548A (en) * 1971-12-03 1975-03-25 Inmont Corp Sealant
US4379190A (en) * 1981-04-06 1983-04-05 E. I. Du Pont De Nemours And Company Filled thermoplastic compositions based on mixtures of ethylene interpolymers
US5276082A (en) * 1990-07-13 1994-01-04 Armstrong World Industries, Inc. Halogen-free floor covering
US5731069A (en) * 1994-01-12 1998-03-24 E. I. Du Pont De Nemours And Company Composite gage and drain hole sealer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872548A (en) * 1971-12-03 1975-03-25 Inmont Corp Sealant
US4379190A (en) * 1981-04-06 1983-04-05 E. I. Du Pont De Nemours And Company Filled thermoplastic compositions based on mixtures of ethylene interpolymers
US5276082A (en) * 1990-07-13 1994-01-04 Armstrong World Industries, Inc. Halogen-free floor covering
US5731069A (en) * 1994-01-12 1998-03-24 E. I. Du Pont De Nemours And Company Composite gage and drain hole sealer

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8398086B2 (en) 2007-08-21 2013-03-19 Toyota Jidosha Kabushiki Kaisha Sealing element and sealing method including fusing the element
WO2014040913A1 (fr) * 2012-09-11 2014-03-20 Sika Technology Ag Agent moussant thermoplastique
US9556318B2 (en) 2012-09-11 2017-01-31 Sika Technology Ag Thermoplastic foaming agent
WO2017036624A1 (fr) * 2015-09-02 2017-03-09 Sika Technology Ag Mousse expansible à la chaleur
CN107922661A (zh) * 2015-09-02 2018-04-17 Sika技术股份公司 可热膨胀的泡沫
EP3344689B1 (fr) 2015-09-02 2020-07-22 Sika Technology AG Mousse expansible à la chaleur
US10899902B2 (en) 2015-09-02 2021-01-26 Sika Technology Ag Heat expandable foam
CN107922661B (zh) * 2015-09-02 2021-06-01 Sika技术股份公司 可热膨胀的泡沫

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