CA2130352A1 - Improved gasket for an aerosol mounting cup - Google Patents
Improved gasket for an aerosol mounting cupInfo
- Publication number
- CA2130352A1 CA2130352A1 CA002130352A CA2130352A CA2130352A1 CA 2130352 A1 CA2130352 A1 CA 2130352A1 CA 002130352 A CA002130352 A CA 002130352A CA 2130352 A CA2130352 A CA 2130352A CA 2130352 A1 CA2130352 A1 CA 2130352A1
- Authority
- CA
- Canada
- Prior art keywords
- gasket
- mounting cup
- measured
- channel
- psi
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D83/00—Containers or packages with special means for dispensing contents
- B65D83/14—Containers or packages with special means for dispensing contents for delivery of liquid or semi-liquid contents by internal gaseous pressure, i.e. aerosol containers comprising propellant for a product delivered by a propellant
- B65D83/38—Details of the container body
-
- 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
- C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
- C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
-
- 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
- C08L23/06—Polyethene
Abstract
A gasket material (24) for sealing a channel (20) of a mounting cup (10) to a container bead (12) is disclosed having a flexural modulus, 1 % secant, of at least about 70,000 psi, as measured by ASTM Method D 790, and a hardness no greater than about 60 Shore D, as measured by ASTM D 2240. Also disclosed is a gasket material (24) comprising a mixture of a stiffer plastic material and a softer plastic material wherein the mixture meets the above flexural modulus and hardness criteria. A preferred material and mixture are disclosed. Preferred dimensions for the gasket on the mounting cup are also disclosed.
Description
WO 93/12901 PCr/US92/11184 2130~52 IMPROVED GASKET FOR AN AEROSOL MOUNTING CUP
Backaround Aerosol dispensing containers have found widespread use in the packaging of fluid materials including a variety of both liquid and powdered particulate products. Such containers are provided with a valve-controlled discharge orifice and operate by the action of a volatile propellant which is confined within the container together with the product to be dispensed. Because the propellant has an appreciable vapor pressure at room temperature, the product in the closed container is maintained under superatmospheric ~15 pressure.
A typical aerosol unit comprises a hollow cylindrical .
container which is tightly closed at one end and is provided -with an opening at its opposite end for rec~iving a dispensing valve assembly. A closure, commonly referred to ~20 as a mounting cup, 6erves a~ the closure for the container and a~ a ~upport for the valve assembly. Typically, the mounting cup comprises a pedestal portion for mounting the valve unit, a panel portion extending from the pedestal portion, a skirt portion depending from the periphery of the panel, and an annul ar channel portion extending outwardly from the skirt. When the mounting cup is placed in seàling position on the container, the channel is positioned over the bead surrounding the container opening and the lower portion of the skirt ad~ acent to the channel i8 flared or ~30 clinched outwardly against the underside of the bead. To `
WO 93/12901 PCI'/US92/11184 ~ r ~
ensure adequate sealing between the closure and the container, the cup is provided with a gasket in the channel, or predominantly in the channel, of the cup In United States Patent Nos 4,546,525 (~the '525 -5 patent~) and 4,547,948 (~the '948 patent~), a novel gasketed mounting cup system, including novel method and apparatus, is described wherein the gasket material is disposed on the mounting aup in the preferred position for effecting a seal between the mounting cup and tbe bead of the container, in an exceptionally rapid and efficient manner to form g~sketed-mounting cups having excellent sealing characteristics In general, the method of invention of the '525 and '948 patents comprises passing a tubular sleeve of ga~ket material onto ~ compre~ible mandrel initially ~`
positioning ~nd aligning the skirt of th~ mounting cup and th~ contiguou~ end of th~ mandr~l such that th~ sl~v~ of ga~kot mat~rial m~y p~B8 onto the skirt, ~aid mandrel having fixed and moveable portions with respect to each other and to their movement toward and away from the mounting cup;
urging the moveable portion of the gasket material bearing mandrel toward the mounting cup such that the gasket material passes onto the skirt of the cup; causing the moveable portion of the mandrel to retract to its initial position, cutting the slQeve at a point between the mounting cup and the mandrQl to l-ave a band of gasket material and subs-qu-ntly, advan¢ing the mounting cup to a station whereat the band o~ the gasket material is urged further ' W093/12901 PCT/US92/111~
Backaround Aerosol dispensing containers have found widespread use in the packaging of fluid materials including a variety of both liquid and powdered particulate products. Such containers are provided with a valve-controlled discharge orifice and operate by the action of a volatile propellant which is confined within the container together with the product to be dispensed. Because the propellant has an appreciable vapor pressure at room temperature, the product in the closed container is maintained under superatmospheric ~15 pressure.
A typical aerosol unit comprises a hollow cylindrical .
container which is tightly closed at one end and is provided -with an opening at its opposite end for rec~iving a dispensing valve assembly. A closure, commonly referred to ~20 as a mounting cup, 6erves a~ the closure for the container and a~ a ~upport for the valve assembly. Typically, the mounting cup comprises a pedestal portion for mounting the valve unit, a panel portion extending from the pedestal portion, a skirt portion depending from the periphery of the panel, and an annul ar channel portion extending outwardly from the skirt. When the mounting cup is placed in seàling position on the container, the channel is positioned over the bead surrounding the container opening and the lower portion of the skirt ad~ acent to the channel i8 flared or ~30 clinched outwardly against the underside of the bead. To `
WO 93/12901 PCI'/US92/11184 ~ r ~
ensure adequate sealing between the closure and the container, the cup is provided with a gasket in the channel, or predominantly in the channel, of the cup In United States Patent Nos 4,546,525 (~the '525 -5 patent~) and 4,547,948 (~the '948 patent~), a novel gasketed mounting cup system, including novel method and apparatus, is described wherein the gasket material is disposed on the mounting aup in the preferred position for effecting a seal between the mounting cup and tbe bead of the container, in an exceptionally rapid and efficient manner to form g~sketed-mounting cups having excellent sealing characteristics In general, the method of invention of the '525 and '948 patents comprises passing a tubular sleeve of ga~ket material onto ~ compre~ible mandrel initially ~`
positioning ~nd aligning the skirt of th~ mounting cup and th~ contiguou~ end of th~ mandr~l such that th~ sl~v~ of ga~kot mat~rial m~y p~B8 onto the skirt, ~aid mandrel having fixed and moveable portions with respect to each other and to their movement toward and away from the mounting cup;
urging the moveable portion of the gasket material bearing mandrel toward the mounting cup such that the gasket material passes onto the skirt of the cup; causing the moveable portion of the mandrel to retract to its initial position, cutting the slQeve at a point between the mounting cup and the mandrQl to l-ave a band of gasket material and subs-qu-ntly, advan¢ing the mounting cup to a station whereat the band o~ the gasket material is urged further ' W093/12901 PCT/US92/111~
2~30352 ~ 3 ~ ~ r ~
onto the skirt of the mounting cup, whereby, the band of gasket material does not extend beyond the skirt of the mounting eup. Subsequently, the gasket is advaneed to the desired position partially within the channel of the mounting cup. The '52S and '948 patents are ineorporated by referenee herein.
The dip tube of the eontainer is usually slightly longer than the height of the eontainer to insure that its end i~ position~d at the bottom of the eontain~r. As shown in Figur- 1, wh-n th- mount~ng eup i- po~ition-d on th-eontainer bead, the dip tube is slightly bent. This ean provide an upward foree whieh ean displaee the mounting eup from the eontainer bead, interfering with proper elinehing.
To ensure that the mounting eup is maintained on the eontainer bead prior to elinehing, protrusions are ereated .
around the skirt of the mounting eup whieh are below the eontainer bead when the mounting eup is in position. Such protrusions 14a are also shown in Figure 1. The force provided by the bent dip tube is generally insuffieient to overcome the retaining force provided by the protrusions.
The protrusions are formed by a tool placed around the pedestal of the mounting eup, which forces out particular seetions of the skirt of the eup.
~n the United States, aero~ol eontainers are typieally filled by the undercap fill~ng m thod. First, the produet to be di~pQnsed i8 d~posit~d lnto the eontainer. Then a mounting cup, including the valve and dip tube, i8 plaeed on ~ r ~ . - 4 -;~035?
the container such that the bead of the container is within the channel of the mounting cup. The filling head of an undercap filling machine then encompasse6 the top of the container, creating an airtight seal. Air is then evacuated from the container. The suction created during evacuation raises the mounting cup off of the container bead.
Propellant is then forced into the container opening beneath the mounting cup and the mounting cup iæ repositioned and clinched to the container bead. During the filling process, suction during evacuation or the force of the propellant during filling can displace the gasket from its position within the channel of the mounting cup, preventing a proper seal on clinching. In some cases, the gasket can be completely displaced by the propellant filling the container, forcing the gasket into the container~ This is referred to as a ~blownn gasket.
Gasket displacements are more likely with the low d~nsity polyet~ylene (nLDPE~) com~only used to form such gaskets. Replacement of LDPE with high density polyethylene (~HDPE~) yields a less effective seal because ~he HDPE is not sufficiently resilient to adequately conform to the metal of the mounting cup.
In addition, various methods of forming gaskets are utilized in the art, yielding varying gasket thickne~s.
Thi~ varlation in gasket thicXn-ss among the several gasket ~ystems, further complicated by the fact that the channel portion of the mounting cups manufactured by the valve WO93/12~1 PCT/US92/111~
Z~3035Z
assembly plants and the annular beads of the aerosol container manufactured by container plants have nominal variations which are within quality control limits, often produce a defective seal in a completed aerosol product which may remain undetect~d until ultimately di~covered by the consumer.
Therefore, a variety of methods have been tried to maintain the gasket in its proper position for sealing. For example, in U.S. Patènt No. 4,559,198, assigned to the assignee of the present invention, annular or radial compressive deformations form ribs which improve the gasket's resistance to being dislodged during undercap filling or otherwise being repositioned on the mounting cup by the gasket returning to its initial position. In U.K.
Patent No. G8 2,206,650, also assigned to the assignee of the patent invention, a thermal adhesive is disclosed which adheres the gasket to its ~inal position partially within the channel of the mounting cup.
In U.S.S.N. 07/552,299, filed on July 18, l990 and also assigned to the assignee of the present invention, a multi-layer gasket comprising a middle layer of a stiffer plastic material and inner and outer layers of so~ter plastic material ad~acent both sides of the middle layer i8 dis~losed. The middle layer is preferably HDPE while the inner and outer layers are preferably LLDPE. Such a gasket, wbile producing ~uperior results, requires additional W093/12901 ` PCT/US92/11184 21~35~ -6-manufacturing steps, adding to the cost and time involved in making and positioning the gasket.
The seal between the mounting cup and the aerosol container remains of great concern to both the valve assembly plants and the filling plants since it must be capable of being air tight for a period of years. In addition, the seal between the mounting cup and the aerosol container muQt be low in C08t to enable aerosol product~ to b- competitive with non-aerosol products in tbe consumer market.
Summary of the Invention In one aspect of the present invention, a plastic polymer is disclosed having a flexural modulus, 1% secant, ~15 of at least about 70,000 p8i as measured by ASTM method D
790 and a hardness no greater than about 60 Shore D as measured by ASTN method D 2240. A flexural modulus of at least about 90,000 psi and a hardness between about 53-56 is preferred. It is also preferred that the gasket be a sleeve`
type gasket and the polymer be a thermoplastic.
In another aspect of the invention, a gasket for sealing a channel of a mounting cup to a bead of a container comprises a mixture of a stiffer plastic material and a softèr pla~tic material which mixture meets the flexural ;~ 25 modulu~ and hardnQss limits de~cribed above. As above, the gasket i8~ preferably a 81eeve type gasket and the plastic material~ are thermopla~tic~.
-7- i';A~ &~
In a preferred embodiment of the invention, the gasket material compri~es a mixture of high density polyethylene (~HDPE~) and linear low density polyethylene (~LLDPE~). The preferred HDPE is about 43% by weight of the gasket and the preferred LLDPE is about 57% by weight of the gasket.
In certain applications, it is also preferred to include a layer of thermal adhesive on the surface of the gasket material to be in contact with the mounting cup. ~;
In a further a~pect of the invention there is a gasket-d mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the -~
skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening;
and a gasket disposed partially within the channel of the lS mounting cup and partially along the skirt of the mounting cup, wherein the gasket material is as described above. In certain applications, it may be preferred to bond the gasket to the mounting cup by a layer of thermal adhesive. In preferred embodiments of the invention, the gasket's 2Q position on the mounting cup meet certain critical requirements.
In a further a~pect of the invention, optimum values and ranges for critical dimensions of the position of the gask~t on th- mounting cup ar di~clo~ed.
~ ' W093/12901 "i'~ ,' PCT/US92/111~
21~0352 -8-Description of the Fiaures Figure 1 is a cross-sectional view of a gasketed mounting cup in accordance with the present invention;
Figure la is a cross-sectional view of the channel of the gasketed mounting cup of Figure 1, clinched to a container bead;
Figure 2 i8 a cross-sectional view of a portion of a gasket prior to its being advanced into the channel of a mounting cup; and Figuro 3 is a cros--sectional view of a portion of the punch preferred for us- in manufacturing the gasketed ~ounting cup o~ th~ pre~Qnt invantion Figure 1 ~how~ a ga~ketod aerosol valve mounting cup of .~ .
the present invention generally designated as 10 resting on ~`; a container bead 12 of an aerosol container (not shown) Figure la shows the channel portion 20 of the gasketed mounting cup 10 clinched to the container bead 12 The mounting cup has a pedestal portion 14 which depends from ~-~ the interior edge of a panel portion 16 A skirt 18 depends from the exterior edge of the panel portion 16 opposite the pèdestal portion 14 and is concentric thereto The top portion of the skirt 18 CUrVQS into an annular ; 25 channel portlon 20 whlch term1natQs in an edge portion 22 , Th~channol porti*n 20, odgo portion 22 and skirt 18 form an annular concav- r-coptor for racei~ng the bead 12 of the WO93/12901 2~30352 PCT~US92/111~
~ r,~ ,rDf ~
aerosol container, as shown. The gasket 24 of the invention is positioned partially within the channel 20 of the mounting cup 10. The gasket 24 has a first portion 24a in contact with part of the channel portion 15 of the mounting cup 10. The gasket 24 al80 has a second port~on 24b in contact with the 6kirt 14 of the mounting cup 10. Al~o shown are dimples 26 which retain the gasket 24 and mounting cup 10 on the container bead prior to undercap filling.
Such dimples are described in more detail in U.S.S.N.
07/814,370, filed on the same day as the present application and assigned to the same assignee. U.S. Serial No.
07/814,370 is incorporated by reference herein.
The mounting cup 10 is preferably a standard mounting cup for use in a standard one inch opening of an aerosol container. The radius ~r~ of the bead 12 of the container is 0.06 inches. Optimum ranges for certain critical dimensions for the gasket's 24 position on the mounting cup 10 have been ascertained and are one aspect of the invention. In such a standard cup, the length nL-l~ of the gasket as measured from the center of the channel 20 of the mounting cup to the end of the second portion 24b is preferably at least 0.150 inches and i5 most preferably about 0.17~ inches. L-l is shown in Figure 1. It has baen found that for optimum s~aling, it is necessary`to have sealing material in the region between the skirt 18 and thQ
container bead 12 proxi~ate numeral ~18~ in Figure la.
These preferred lengths ensure that the second portion 24b W093/12901 '~ ~ ~J ~: PCT/US92/11184 2~30352 -lo-of the gasket material 24 is properly positioned along the skirt 18 of the mounting cup 11 to provide sealing material in this critical region. If the radius r of the container bead 19 is larger then 0.06 inches, a larger length L-l would be required. If the radius r is smaller than 0.06 inches, a shorter length L-l would be acceptable.
The gasket material 24 should be positioned far enough into the channel 20 of the mounting cup such that the diameter ~d~ of the gasket flare, as measured at the end of the first portion 24~ of the gasket 24 through the center of the mounting cup 10, as shown in Figure 1, is preferably greater than about 1.100 inches. It is more preferably greater than about 1.180 inches. It is most preferably about 1.200 inches. Such a flare diameter places the end of the first portion 24a of the gasket 20 at approximately the 10 o'clock position within the annular convex receptor.
~uch placement of the g~sket ~how~ improved res~stance to dislodgement from the channel 20 of the mounting cup 10.
To achieve t~ preferred flare diam~ter, the length ~-2~ of the gasket material after being cut from the sleeve (as described in the '525 and '948 patents), referred to as its ~cut length, should be between about ~.250-0.285 inches.
See Figure 2.
The gasket 20 is preferably between about 0.013-0.016 inches thick. It i8 most preferably 0.014 inches thick.
-~ While it i~ preferred to utilize these dimensions with the preferred gasket material described below, these , .~0 93/12901 2~.3035Z PCI/US92/11184 dimensions can improve the performance of any gasket material on a standard mounting cup. In addition, the optimum dimensions and positioning of the gasket can improve sealing in non-sleeve type gaskets, applied by processes other than the preferred proce~s described herein.
The gasket material 24 of the invention is a plastic polymer having a flexural modulus, 1% secant, of at least about 70,000 p8i as measured by ASTM method D 790, and a hardne~ no greater than about 60 Shore D a~ measured by ASTM mQthod D 2240~ Such a material ha~ a ~tiffnes~
sufficiQnt to maintain th~ ga~k~t in position part$ally within the channel 20 of a mounting cup and is sufficiently soft to provide an adequate seal between the channel 20 of the mounting cup 10 and a container bead 12 when clinched.
Preferably, the flexural modulus is at least about 90,000 psi and the hardness is 56 or less, as measured above.
If the gasket material is in the preferred form of a sleeve gasket, then the plastic is preferably a thermoplastic polymer. Sleeve gaskets are preferably positioned in accordance with the process described in the '525 and '948 patents, and U.S. Serial No. 07/814,370.
Thermoplastics are preferred for use with sleeve gaskets because they soften when heated, easing placement within the channel of the mounting cup, and hard~n on cooling, retaining their shapo confor~ing to the chann~l of the cup.
Suitable thQrmoplastic ~aterials include polyethylenes, polypropylenes, other polyolefinic compounds s=ch as .
i;A~. ~t W093/129~1 ~;ff~ , PCT/US92/111 2 ~ 30 3~2 -12-ethylvinylacetate (~EVA~) copolymers, ethyl vinyl alcohol copolymers, polypropylene and ethylene copolymers, and polyethylene modified by elastomers such as rubber. In addition, polyurethanes, polyesters, ionomers, polycarbonates and some polyamides such as nylon 11, can be used. The particular plastic chosen needs to be chemically resistant to the product and propellant in the aerosol container and could, therefore, vary depending on the application. The plastic also needs to have sufficient resistance to environmental stress to withstand the pressure and compression forces endured by aerosol gaskets.
Environmental stress crack resistance as measured by D 1~93 of at least about 400 hours is preferred. The plastic needs to be resistant to cold flow as well.
It is believed that DEHD 1796 t~DEHD~), a polyethylene available from Union Car~ide, will provide satisfactory performance. DEHD is a commodity material used by Union Carbide to form other plastics, such as DHDA 2463, also available from Union Carbidë. Typical property data for DEHD follows:
DEHD
Test Typical Property Method Value Tensile Str~ngth ~br~ak), pBi (MPa) D 638 3000 (20.?) Ultimate Elongation, ~ D638 ~800 Flexural ~odulus, psi (NPa) D 790 100,000 ~690) WO 93/t2901 Z13035~ PCT/US92/111~
DEHD ~Cont~
Test Typical Property Method Value Tensile Strength (yield), psi (MPa) D 638 2750 (l9.0) Brittleness Temperature, ~C D 746 ~-95 Melt Index, g/lO minutes D 1238 0.
Deflection Temperature at 66 psi (0.46 MPa) F (C) D 648 140 (60) Vicat Softening Temperature, F (-C) D 1525 244 (118) Bulk Density, lbs/ft (g/cm3) D 1895 35-37 (0.56-0.59) Density at 73-F (23 C), g/cm3 ~compound) D 1505 0.939 Environmental Stress Crack Resistance D 1693 >2000 lO lgap, ~20 Hours (AS~M D 1693 cond. B) Durometer Hardness, Short ~D~ D 2240 56 Linear Thermal Coefficient of `Expansion D ~95 1.20 x 10-4 in/in/-C(-30C to +30~C) Izod impact, ft - lbs/in (j/m) notch 23~C D 258 2.3 (123) M~ltin~ Point, ~C 126.3 Cry~talliz~tion Point, C 112.8 The gasket can also comprisa a mixture o~ a first plastic material providing sufficient stiffness to maintain the gasket in position partially within the channel 20 of the mounting cup 10 and a softer plastic material providing sufficient softness to pro~ide a reliable seal between the WOg3/12901 PCT/US921111~
channel 20 of the mounting cup 10 and the container bead 12 when clinched such that the mixture has a flexural modulus, 1% secant, of at least about 70,000 psi, as measured by ASTM
method D 790, and preferably at least about 90,000 psi. The - 5 mixture has a hardness no greater than about 60 Shore D, as measured by ASTM method D 2240, and is preferably 56 or less. Generally, the stiffer material will have higher density than the softer material. As above, if the gasket is the preferred d eeve gasket, the polymers forming the :
mixture arQ prefQrably thermoplastics. The mixture should have sufficient resistance to environmental stress to withstand the pressure and compression forces endured by a-rosol cont~iner gaskQt~. As above, environmental stress crack resi~tanc- of at lea~t about 400 ~8 pref-rrQd. The plastio ~u-t b- r--1-tant to cold ~low, a~ w ll.
Suitable stiffer materials include ~DPE, other stiff polyethylenes such as LLDPE of suitable molecular weight, polyamides, polycarbonates, polypropylenes, polyesters, acrylonitrilebutadienstyrenes (~ABS~), or acetyls. The flexural modulus of the stiffer materials is greater than 70,000 psi as measured as described above, and is preferably greater than 90,000 psi. Suitable æofter materials include æome polyethylenes and other polyolefins, ethylene-ethyl ac ylate copolymer, poly-sters, polyurethanes and most other the plastic lastomers. The hardne~s of the softer mat-rials is 1-8~ than 60 as ~easured as described above, ; and i8 pr-f-rably below 56.
WO93/12901 PCT/US92/111~
2~30 ; . ., !
The plastics chosen must be compatible in order to form a homogenous mixture. The materials chosen also need to be chemically resistant to the product and propellant and could t~erefore vary depending on the application. Suitable S mixturs~ include HDPE and LLDPE or LDPE, or polyethylene and polypropylene.
The relative quantity of the softer and stiffer plastic materials combined to form the mixture having the characteristics described above depends on their softness -and stiffness. For example, if the soft material and stiff material are each close to the desired hardness and flexural modulus values, mixtures of between about 60% of one to 40%
of the other may be utilized to yield mixtures having the characteristics of hardness and flexural modulus described above. If either or both of the hardness and flexural modulus values of either material are far from the desired values, larger quantities of one material may be required to yield the desired values in the mixture. For example, mixtures of between about 60%-70% of one to about 40%-30% of the other, about 70%-80% of one to about 30%-20% of the other or even greater than 80% of one and less than 20% of the other, may be utilized.
The preferred stiffer material is HDPE having a flexural mcdulus of at lsast about 140,000 psi. A higher flexural modulus is even more preferred. The preferred HDPE is Altav n~ 6200B HDPE, available from Plastics Del Logo, C.A.
Venezuela. Preferably, the LLDP~ has a hardness no greater WO93/12901 ~ PCT/US92/111 2 ~ 30 3r~Z -16-than about 55 and more preferably no greater than about 50.
The prefQrred LLDPE is DNDA-7340 Natural 7 (~DNDA-7340~), available from Union Carbide.
Typical property data for the preferred HDPE and LLDPE
appear below:
Altav~n~ 6200B
Covenin ASTM Typical Properties Method Method Value Melt Index 1552 D 1238 0.40 g/10 min Density - D 1505 0.0958 g/cm3 Yield strength 1357 D 638 280 Kg/cm2 Tensi}e strength at break 1357 D 638 320 Kg/cm2 :Elongation at break 1357 D 638 >500%
-~ Izod Impact strength 822 D 256 12 Xg. cm/cm ; Environmental cracking resistance - D 693 >400 hours Flexural Modulus 1% Secant D 790 . 145,000 Hardness D 2~40 ~66 Propertv Test Method ~vpical Values Melt Index D 1238 0.8 g/10 minutes Density D 1505 0.920 g/cm Flexural Modulu~
.1% Secant D 638 34,000 psi;234 Mpa Tensil~ Strength D 638 2,250 psi:l5.5 Mpa ,~ .
W093/12901 2130352 PCT/US92/111~
--17-- ~,, 1', tr ! X~;
DNDA-73~0 ~oont~) Property Test Nethod Typical Values s Ultimate Elongation D 638 500 %
Bent Strip Craek Resistanee, hrs~X~ F
100% ~Igepal~ D 1693 >500 10% ~Igepal~ >soo Brittleness Temperature D 746Below -lOO-C
Flex. Life, Cyeleæ
to Fail UCC Method 140,000 20Minimum Shear Rate To Melt Fraeture, see~1 UCC Nethod 4,000 Hardness D 2240 -45 With the preferred HDPE and LLDPE described above, mixtures within the range of about 62%-52% LLDPE to about 38*-48% HDPE are preferred. A mixture of 57% by weight of the DNDA-7340, 43% by weight of the Altaven~ 6200B, is eurrently being used.
Alternatively, a soft material, such as LLDPE, can be stiffened, increasing its flexural modulus by the addition of inorganic filler or fiber. Fiberglass fiber, glass beads, talc, or calcium carbonate are suitable additives.
Coupling agents may be required to bond the inorganic filters to the organie base material, as is known in the art.
In eertain applieations, sueh as where propellant is inserted into the eontainer at high pressure after the produet has been-inserted, an adhesive is preferably used to W093/12901 ~ $ PCT/US92/1t184 further secure the gasket of the invention to the mounting cup If the gasket is of the sleeve type, applied in accordance with the proceæs of the '525 and '948 patents, it is further preferred to use a thermal adhesive The thermal adhesive prevents the gasket from prematurely bonding to the mounting cup, preventing its advancement into its final position partially within the channel 20 of the mounting cup lO Heating of the mounting cup prior to the final advancement of the gasket in the gasket placement process melts the thermal adhesive, activating the adhesive After the gasket is advanced and the mounting cup is removed from the h at ourc-, the temp-rature of th~ mounting cup drops to room temperature and the thermal adhesiv~ bonds the gasket to the mounting cup Pr~f~rably, tho adhe~ive is a mlxture Or about 64 67%
Exxon Escor acid terpolymer ATX 325 (~ATX 325~), about 35 67% DNDA-7340 and O 66% H Xohnstamm PB 3962 blue dry colorant The blue colorant is added to enable the visible inspection of the sleeve gasket to determine if the adhesive is evenly distributed It also eases identification of the gasket on the mounting cup The thermal adhesive layer is preferably about 0 00075 inches thick Typicai property data for ATX 325 appear below AT~ 325 25PROPERTIES TM METHOD VA~UES
Molt Ind~x D 1238(E) 20 - g/10 ~ln , ;, ~ .
93/12901 2~30352 PCT/USg2/11184 -19- ~a`~
ATX 325 (cont~
PROPERTIES ~STM METHOD VALUES
Acid Number Exxon Method 45 Milligrams KOH/gm polymer Density ~ ~ 792 0.942 10 g/cc Tensile Strength D 638 1200 psi (MPa) (8) 15Elongation % D 638 ~Compression Molded Type IV specimens, crosæhead speed 2 in/min (5.1 cm/min)) 1800 Flexural Modulus D 790 1300 psi (MPa) (9) Tensile Impact, D 1822(S) 25ft-lb /in2 (XJ/m2)~
73-F (23-C) 350 (735) -43-F (-40-C) 255 (535) Hardness, Shore D D 2240 21 DSC Melting Point D 3417 149 (65) F (-C) Viscat Softening Point D 1525 140 (60) F (-C), 200 g load (Rate B) To form the preferred gasket of the invention, about 57%
by weight of DND~-7340 LLDPE and about 43% by weight of Altaven~ HDPE 6200B were added to a lD Banbury Mixer with a capacity of 30 pounds and mixed for about 2.5 minutes. Such a mixQr i~ available from Farrel Machinery, for example.
The mixing ~tarted at room temperature and reached 380-400-F by the end o~ the mixing period. The mixture wa~ then conveyed to a Farrel 4t inch extruder, preh-ated to about WO 93/12901 r ~ PCr/US92/1 1 184 2i3035Z
400-420F. The mixture was discharged from the extruder at a rate of about 600 pounds per hour to a cooling trough and a Cumberland Strand Pelletizer, available from Cumberland, Inc. The pelletized mixture was later converted into a - 5 sleeve gasket by extrusion, as is known in the art. The sleeve gasket should be visually inspected to ensure that the gasket thickness is uniform. Thinned areas of the sleeve can interfere with the integrity of the seal, causing displacement of the gasket prior to clinching, or leaks.
~;~ 10 To form the preferred thermal adhesive, about 64.67% by weight of ATX 325, about 35.67% by weight of DNDA-7340 LLDPE
and O.S5% by weight of H. Xohnstamm PB 3962 blue colorant were ~dded to the Banbury mixer and mixed for 2 minutes, up to 300-320-F. The mixture was then conveyed to an extruder and extruded at a rat~ of about 600 pounds per hour at between 300-320'F. It was then pelletized as above. The thermal adhe~ive and sleeve gasket were coextruded into a tool where the layers were merged, as is known in the art.
The gasket material wa~ approximately 0.014 inche~ thicX
while the layer of thermal adhesive, which is located on the inside surface of the sleeve gasket material, was approximately 0.00075 inches thick. The sleeve gasket should be visually inspected to ensure that the thermal adhesive has been applied evenly.
The gasket of the invention i~ prefer~bly positioned on the mounting cup a8 g~n rally de~cribed in the '525 and '948 patents. a singl~ station gagket ~ounting cup assembly ~:' W~93~12901 2130352 PCT~USg2/~
machine is utilized instead of the six station assembly machine shown in Figure 3 of the '948 pat~nt It has been found that the sleeve gasket material may be positioned on a single mounting cup faster and more accurately than if - 5 sleeve gasket material is concurrently positioned on BiX
mounting cups In addition, higher temperatures are curr~ntly used than those disclosed in thQs~ patQnts A mounting cup temperature of at least about 150 F and pr~f~rably about 170 F, a- m asurod o~ th- rac-way about l foot from the punch station, les~ than one second after the final positioning of the gasket within the channel of the mounting cup, is utilized This is a convenient point to measure the temperature It is believed that the temperature of the mounting cup is 20 - 30 F higher while the gasket is being advanced to its final position on the mounting cup At 170 F, the gasket's increased pliability further eases its advancement into the channel of the cup, as does the wetting provided by melting the thermal adhesive At higher temperatures, the gasket could degrade and become too soft However, mixtures including higher percentages of HDPE can tolerate higher temperatures A one piece punch 30 is preferred for advancing the gasket 24 into the channel 20 of the mounting cup The - punch preferably includes an exten~ion 30a for engaging th~
end o~ tb- first portion 24a of th gasket 24 as it is being adv~anc~d into the cbann~l 20 of th- mounting cup lO as shown in Figure 3 The xtension 30a ensures that the gask t is .
WO 93/12901 ! `' ~ PCI/US92/11184 2~30352 -22-advanced to its preferred position within the channel 20 of the cup, yielding the preferred gasket flare d, as shown in Figure 1. A shoulder 34 is provided to engage the top of the second portion 24b of the gasket 24 and to advance the gasket to its final position. The punch further includes a series of lugs 32 formed by pins 32a pressfit into the punch 30. These lugs form the dimples 26 shown in Figure 1 and ~described further in U.S. Serial No. 07/814,370. Eurther details concerning the process and preferred puncb utilized -in manufacturing the gasketed mounting cup of the present invention are described in U.S.S.N. 07/814,370.
Comparative tests of the gasket in accordance with the preferred embodiments of the present invention with con~entional gaskets of LLDPE have ~;hown that the gasket of the present invention i~ more resistant to blown gasket failure and has more consistent performance. The forces applied to a gasket in the channel of th~ mounting cup during undercap filling were simulated by a bench device comprising a fixture shaped like a container bead positioned within an airtight chamber. The mounting cup WZIS placed on the fixture and a cap E~eal, pres~ure loaded by an air cylinder, was pressed down on the mounting cup with an adjustable force. Air was pumped into the chamber at a desired pressure. When the pressure within the chamber overcame the force exerted by the air cylinder Imd cap seal on the mounting cup, th mounting cup rose. Air then passed between th~ channel of the mounting cup and the fixture, , ~
W093/12901 ~30352 PCT/uS92/~
-23- ~ t past the gasket, just as propellant is forced through the channel into a container during undercap filling.
12 gaskets are considered a representative test sample.
The maximum pressure where none of the 12 test gaskets failed (~Pl~) and the minimum pressure that caused all 12 to fail (~P2~) were det~rmin~d. A failure is a blown gasket.
A higher Pl indicates better resistance to blown qasket failure while a ~mall difference between Pl and P2 indicates consist~nt product porformanc~. The pre~sur~ of the cap ~eal wa~ varied ~uoh that if all 12 ga~kets did not pa~s the tost, the pre~ure was lower~d. If all 12 p~ d, th-pressure was raised until Pl was determined. Then the pressure was increased until all 12 gaskets failed. Pl and P2 can be converted into load forces by multiplying the lS pressure values in the air cylinder providing the force against the cap seal, by 12.5, which is the approximate area of the cylinder in inches.
For gaskets of LLDPE, adhered to the mounting cup by the thermal adhesive described above, at a filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 = 28 psi (350 lbs).
At a fillinq pressure of 800 psi, Pl = lO psi (125 lbs) and P2 = 24 psi (300 lbs).
For gaskets of Altaven~ 6200B and DNDA-7340 of 43$ and - 57%, respectively~ bonded to th~ ~ounting cup by the th~rmal adhe~lv~ de~cr~b d a~ ve, at a filling pro~ure of 600 p8i, both Pl and n - 28 p8i (350 lb~). At a ~illing pr~ure of 800 p~i, Pl - 26 p~i (325 lbs) and P2 - 28 p~i (3S0 lb~).
WO93/12901 PCT/US921111~
2~303SZ -24-These results demonstrate that the gasket material of the present invention is far superior to conventional ga6k~ts of ~DPE in resistance to blown gasket failure and in consistency of performance.
Comparative tests varying the cut length of the gasket, which effects the flare diameter of the gasket within the channel of the mounting cup, showed imprQved results as the cut length was increased. For gaskets of a height of 0.225 inches, comprised entirely of LLDPE and adhered to the mounting cup by the thermal adhesive described above, at a filling pressure of 600 psi, Pl s 10 psi (125 lbs) and P2 =
28 psi (350 lbs). At a filling pressure of 800 psi, Pl = 8 ;; psi (100 lbs) and P2 = 26 psi (325 lbs).
- A~ a height of 0.250 inche~, all other variables being the ~ame as above, at a filling pre~sure of 600 psi, Pl 5 14 psi (175 lbs) and P2 3 28 psi (350 lbs). At a filling pressure of 800 psi, Pl = 10 psi (125 lbs) and P2 = 24 psi (300 lbs).
At a height of 0.275 inches, all other variables being the same as above, at a filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 = 28 psi (350 lbs). At a filling pressure of 800 psi, Pl - 12 psi (150 lbs) and P2 = 18 psi (225 lbs).
~omparative t~t~ varying th~ d~sign o~ the punch show~d improved result~ with a one piec~ punch including an extQnsion 30a for engaging the gaaket as shown in Figure 3, ;~ over a two piece punch. For a LLDPE gasket with a cut .
21303S~
-25~ c~;
length of 0.270 inches bonded to the mounting cup by the thermal adhesive described above, and a cup temperature of 154-F, applied with a two piece punch, at filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 - 28 psi (350 lbs).
At a filling pressure of 800 psi, Pl z 12 pBi (150 lbs) and P2 = 18 psi (225 lbs).
With the one piece punch of Figure 3, all other variables being equal, at a filling pressure 600 psi, Pl = 16 psi (200 lbs) and P2.= 26 psi (325 lbs). At a filling pressure of 800 psi, Pl = 14 lbs) psi (175 lbs) and P2 = 24 psi (300 lbs).
The preferred characteristics of material, thermal adhesive, cut length and punch design each demonstrated improved resistance to dislodgement and consistency of performance. Taken togather, the preferred characteristics yield a superior gasketed mounting cup.
onto the skirt of the mounting cup, whereby, the band of gasket material does not extend beyond the skirt of the mounting eup. Subsequently, the gasket is advaneed to the desired position partially within the channel of the mounting cup. The '52S and '948 patents are ineorporated by referenee herein.
The dip tube of the eontainer is usually slightly longer than the height of the eontainer to insure that its end i~ position~d at the bottom of the eontain~r. As shown in Figur- 1, wh-n th- mount~ng eup i- po~ition-d on th-eontainer bead, the dip tube is slightly bent. This ean provide an upward foree whieh ean displaee the mounting eup from the eontainer bead, interfering with proper elinehing.
To ensure that the mounting eup is maintained on the eontainer bead prior to elinehing, protrusions are ereated .
around the skirt of the mounting eup whieh are below the eontainer bead when the mounting eup is in position. Such protrusions 14a are also shown in Figure 1. The force provided by the bent dip tube is generally insuffieient to overcome the retaining force provided by the protrusions.
The protrusions are formed by a tool placed around the pedestal of the mounting eup, which forces out particular seetions of the skirt of the eup.
~n the United States, aero~ol eontainers are typieally filled by the undercap fill~ng m thod. First, the produet to be di~pQnsed i8 d~posit~d lnto the eontainer. Then a mounting cup, including the valve and dip tube, i8 plaeed on ~ r ~ . - 4 -;~035?
the container such that the bead of the container is within the channel of the mounting cup. The filling head of an undercap filling machine then encompasse6 the top of the container, creating an airtight seal. Air is then evacuated from the container. The suction created during evacuation raises the mounting cup off of the container bead.
Propellant is then forced into the container opening beneath the mounting cup and the mounting cup iæ repositioned and clinched to the container bead. During the filling process, suction during evacuation or the force of the propellant during filling can displace the gasket from its position within the channel of the mounting cup, preventing a proper seal on clinching. In some cases, the gasket can be completely displaced by the propellant filling the container, forcing the gasket into the container~ This is referred to as a ~blownn gasket.
Gasket displacements are more likely with the low d~nsity polyet~ylene (nLDPE~) com~only used to form such gaskets. Replacement of LDPE with high density polyethylene (~HDPE~) yields a less effective seal because ~he HDPE is not sufficiently resilient to adequately conform to the metal of the mounting cup.
In addition, various methods of forming gaskets are utilized in the art, yielding varying gasket thickne~s.
Thi~ varlation in gasket thicXn-ss among the several gasket ~ystems, further complicated by the fact that the channel portion of the mounting cups manufactured by the valve WO93/12~1 PCT/US92/111~
Z~3035Z
assembly plants and the annular beads of the aerosol container manufactured by container plants have nominal variations which are within quality control limits, often produce a defective seal in a completed aerosol product which may remain undetect~d until ultimately di~covered by the consumer.
Therefore, a variety of methods have been tried to maintain the gasket in its proper position for sealing. For example, in U.S. Patènt No. 4,559,198, assigned to the assignee of the present invention, annular or radial compressive deformations form ribs which improve the gasket's resistance to being dislodged during undercap filling or otherwise being repositioned on the mounting cup by the gasket returning to its initial position. In U.K.
Patent No. G8 2,206,650, also assigned to the assignee of the patent invention, a thermal adhesive is disclosed which adheres the gasket to its ~inal position partially within the channel of the mounting cup.
In U.S.S.N. 07/552,299, filed on July 18, l990 and also assigned to the assignee of the present invention, a multi-layer gasket comprising a middle layer of a stiffer plastic material and inner and outer layers of so~ter plastic material ad~acent both sides of the middle layer i8 dis~losed. The middle layer is preferably HDPE while the inner and outer layers are preferably LLDPE. Such a gasket, wbile producing ~uperior results, requires additional W093/12901 ` PCT/US92/11184 21~35~ -6-manufacturing steps, adding to the cost and time involved in making and positioning the gasket.
The seal between the mounting cup and the aerosol container remains of great concern to both the valve assembly plants and the filling plants since it must be capable of being air tight for a period of years. In addition, the seal between the mounting cup and the aerosol container muQt be low in C08t to enable aerosol product~ to b- competitive with non-aerosol products in tbe consumer market.
Summary of the Invention In one aspect of the present invention, a plastic polymer is disclosed having a flexural modulus, 1% secant, ~15 of at least about 70,000 p8i as measured by ASTM method D
790 and a hardness no greater than about 60 Shore D as measured by ASTN method D 2240. A flexural modulus of at least about 90,000 psi and a hardness between about 53-56 is preferred. It is also preferred that the gasket be a sleeve`
type gasket and the polymer be a thermoplastic.
In another aspect of the invention, a gasket for sealing a channel of a mounting cup to a bead of a container comprises a mixture of a stiffer plastic material and a softèr pla~tic material which mixture meets the flexural ;~ 25 modulu~ and hardnQss limits de~cribed above. As above, the gasket i8~ preferably a 81eeve type gasket and the plastic material~ are thermopla~tic~.
-7- i';A~ &~
In a preferred embodiment of the invention, the gasket material compri~es a mixture of high density polyethylene (~HDPE~) and linear low density polyethylene (~LLDPE~). The preferred HDPE is about 43% by weight of the gasket and the preferred LLDPE is about 57% by weight of the gasket.
In certain applications, it is also preferred to include a layer of thermal adhesive on the surface of the gasket material to be in contact with the mounting cup. ~;
In a further a~pect of the invention there is a gasket-d mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the -~
skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening;
and a gasket disposed partially within the channel of the lS mounting cup and partially along the skirt of the mounting cup, wherein the gasket material is as described above. In certain applications, it may be preferred to bond the gasket to the mounting cup by a layer of thermal adhesive. In preferred embodiments of the invention, the gasket's 2Q position on the mounting cup meet certain critical requirements.
In a further a~pect of the invention, optimum values and ranges for critical dimensions of the position of the gask~t on th- mounting cup ar di~clo~ed.
~ ' W093/12901 "i'~ ,' PCT/US92/111~
21~0352 -8-Description of the Fiaures Figure 1 is a cross-sectional view of a gasketed mounting cup in accordance with the present invention;
Figure la is a cross-sectional view of the channel of the gasketed mounting cup of Figure 1, clinched to a container bead;
Figure 2 i8 a cross-sectional view of a portion of a gasket prior to its being advanced into the channel of a mounting cup; and Figuro 3 is a cros--sectional view of a portion of the punch preferred for us- in manufacturing the gasketed ~ounting cup o~ th~ pre~Qnt invantion Figure 1 ~how~ a ga~ketod aerosol valve mounting cup of .~ .
the present invention generally designated as 10 resting on ~`; a container bead 12 of an aerosol container (not shown) Figure la shows the channel portion 20 of the gasketed mounting cup 10 clinched to the container bead 12 The mounting cup has a pedestal portion 14 which depends from ~-~ the interior edge of a panel portion 16 A skirt 18 depends from the exterior edge of the panel portion 16 opposite the pèdestal portion 14 and is concentric thereto The top portion of the skirt 18 CUrVQS into an annular ; 25 channel portlon 20 whlch term1natQs in an edge portion 22 , Th~channol porti*n 20, odgo portion 22 and skirt 18 form an annular concav- r-coptor for racei~ng the bead 12 of the WO93/12901 2~30352 PCT~US92/111~
~ r,~ ,rDf ~
aerosol container, as shown. The gasket 24 of the invention is positioned partially within the channel 20 of the mounting cup 10. The gasket 24 has a first portion 24a in contact with part of the channel portion 15 of the mounting cup 10. The gasket 24 al80 has a second port~on 24b in contact with the 6kirt 14 of the mounting cup 10. Al~o shown are dimples 26 which retain the gasket 24 and mounting cup 10 on the container bead prior to undercap filling.
Such dimples are described in more detail in U.S.S.N.
07/814,370, filed on the same day as the present application and assigned to the same assignee. U.S. Serial No.
07/814,370 is incorporated by reference herein.
The mounting cup 10 is preferably a standard mounting cup for use in a standard one inch opening of an aerosol container. The radius ~r~ of the bead 12 of the container is 0.06 inches. Optimum ranges for certain critical dimensions for the gasket's 24 position on the mounting cup 10 have been ascertained and are one aspect of the invention. In such a standard cup, the length nL-l~ of the gasket as measured from the center of the channel 20 of the mounting cup to the end of the second portion 24b is preferably at least 0.150 inches and i5 most preferably about 0.17~ inches. L-l is shown in Figure 1. It has baen found that for optimum s~aling, it is necessary`to have sealing material in the region between the skirt 18 and thQ
container bead 12 proxi~ate numeral ~18~ in Figure la.
These preferred lengths ensure that the second portion 24b W093/12901 '~ ~ ~J ~: PCT/US92/11184 2~30352 -lo-of the gasket material 24 is properly positioned along the skirt 18 of the mounting cup 11 to provide sealing material in this critical region. If the radius r of the container bead 19 is larger then 0.06 inches, a larger length L-l would be required. If the radius r is smaller than 0.06 inches, a shorter length L-l would be acceptable.
The gasket material 24 should be positioned far enough into the channel 20 of the mounting cup such that the diameter ~d~ of the gasket flare, as measured at the end of the first portion 24~ of the gasket 24 through the center of the mounting cup 10, as shown in Figure 1, is preferably greater than about 1.100 inches. It is more preferably greater than about 1.180 inches. It is most preferably about 1.200 inches. Such a flare diameter places the end of the first portion 24a of the gasket 20 at approximately the 10 o'clock position within the annular convex receptor.
~uch placement of the g~sket ~how~ improved res~stance to dislodgement from the channel 20 of the mounting cup 10.
To achieve t~ preferred flare diam~ter, the length ~-2~ of the gasket material after being cut from the sleeve (as described in the '525 and '948 patents), referred to as its ~cut length, should be between about ~.250-0.285 inches.
See Figure 2.
The gasket 20 is preferably between about 0.013-0.016 inches thick. It i8 most preferably 0.014 inches thick.
-~ While it i~ preferred to utilize these dimensions with the preferred gasket material described below, these , .~0 93/12901 2~.3035Z PCI/US92/11184 dimensions can improve the performance of any gasket material on a standard mounting cup. In addition, the optimum dimensions and positioning of the gasket can improve sealing in non-sleeve type gaskets, applied by processes other than the preferred proce~s described herein.
The gasket material 24 of the invention is a plastic polymer having a flexural modulus, 1% secant, of at least about 70,000 p8i as measured by ASTM method D 790, and a hardne~ no greater than about 60 Shore D a~ measured by ASTM mQthod D 2240~ Such a material ha~ a ~tiffnes~
sufficiQnt to maintain th~ ga~k~t in position part$ally within the channel 20 of a mounting cup and is sufficiently soft to provide an adequate seal between the channel 20 of the mounting cup 10 and a container bead 12 when clinched.
Preferably, the flexural modulus is at least about 90,000 psi and the hardness is 56 or less, as measured above.
If the gasket material is in the preferred form of a sleeve gasket, then the plastic is preferably a thermoplastic polymer. Sleeve gaskets are preferably positioned in accordance with the process described in the '525 and '948 patents, and U.S. Serial No. 07/814,370.
Thermoplastics are preferred for use with sleeve gaskets because they soften when heated, easing placement within the channel of the mounting cup, and hard~n on cooling, retaining their shapo confor~ing to the chann~l of the cup.
Suitable thQrmoplastic ~aterials include polyethylenes, polypropylenes, other polyolefinic compounds s=ch as .
i;A~. ~t W093/129~1 ~;ff~ , PCT/US92/111 2 ~ 30 3~2 -12-ethylvinylacetate (~EVA~) copolymers, ethyl vinyl alcohol copolymers, polypropylene and ethylene copolymers, and polyethylene modified by elastomers such as rubber. In addition, polyurethanes, polyesters, ionomers, polycarbonates and some polyamides such as nylon 11, can be used. The particular plastic chosen needs to be chemically resistant to the product and propellant in the aerosol container and could, therefore, vary depending on the application. The plastic also needs to have sufficient resistance to environmental stress to withstand the pressure and compression forces endured by aerosol gaskets.
Environmental stress crack resistance as measured by D 1~93 of at least about 400 hours is preferred. The plastic needs to be resistant to cold flow as well.
It is believed that DEHD 1796 t~DEHD~), a polyethylene available from Union Car~ide, will provide satisfactory performance. DEHD is a commodity material used by Union Carbide to form other plastics, such as DHDA 2463, also available from Union Carbidë. Typical property data for DEHD follows:
DEHD
Test Typical Property Method Value Tensile Str~ngth ~br~ak), pBi (MPa) D 638 3000 (20.?) Ultimate Elongation, ~ D638 ~800 Flexural ~odulus, psi (NPa) D 790 100,000 ~690) WO 93/t2901 Z13035~ PCT/US92/111~
DEHD ~Cont~
Test Typical Property Method Value Tensile Strength (yield), psi (MPa) D 638 2750 (l9.0) Brittleness Temperature, ~C D 746 ~-95 Melt Index, g/lO minutes D 1238 0.
Deflection Temperature at 66 psi (0.46 MPa) F (C) D 648 140 (60) Vicat Softening Temperature, F (-C) D 1525 244 (118) Bulk Density, lbs/ft (g/cm3) D 1895 35-37 (0.56-0.59) Density at 73-F (23 C), g/cm3 ~compound) D 1505 0.939 Environmental Stress Crack Resistance D 1693 >2000 lO lgap, ~20 Hours (AS~M D 1693 cond. B) Durometer Hardness, Short ~D~ D 2240 56 Linear Thermal Coefficient of `Expansion D ~95 1.20 x 10-4 in/in/-C(-30C to +30~C) Izod impact, ft - lbs/in (j/m) notch 23~C D 258 2.3 (123) M~ltin~ Point, ~C 126.3 Cry~talliz~tion Point, C 112.8 The gasket can also comprisa a mixture o~ a first plastic material providing sufficient stiffness to maintain the gasket in position partially within the channel 20 of the mounting cup 10 and a softer plastic material providing sufficient softness to pro~ide a reliable seal between the WOg3/12901 PCT/US921111~
channel 20 of the mounting cup 10 and the container bead 12 when clinched such that the mixture has a flexural modulus, 1% secant, of at least about 70,000 psi, as measured by ASTM
method D 790, and preferably at least about 90,000 psi. The - 5 mixture has a hardness no greater than about 60 Shore D, as measured by ASTM method D 2240, and is preferably 56 or less. Generally, the stiffer material will have higher density than the softer material. As above, if the gasket is the preferred d eeve gasket, the polymers forming the :
mixture arQ prefQrably thermoplastics. The mixture should have sufficient resistance to environmental stress to withstand the pressure and compression forces endured by a-rosol cont~iner gaskQt~. As above, environmental stress crack resi~tanc- of at lea~t about 400 ~8 pref-rrQd. The plastio ~u-t b- r--1-tant to cold ~low, a~ w ll.
Suitable stiffer materials include ~DPE, other stiff polyethylenes such as LLDPE of suitable molecular weight, polyamides, polycarbonates, polypropylenes, polyesters, acrylonitrilebutadienstyrenes (~ABS~), or acetyls. The flexural modulus of the stiffer materials is greater than 70,000 psi as measured as described above, and is preferably greater than 90,000 psi. Suitable æofter materials include æome polyethylenes and other polyolefins, ethylene-ethyl ac ylate copolymer, poly-sters, polyurethanes and most other the plastic lastomers. The hardne~s of the softer mat-rials is 1-8~ than 60 as ~easured as described above, ; and i8 pr-f-rably below 56.
WO93/12901 PCT/US92/111~
2~30 ; . ., !
The plastics chosen must be compatible in order to form a homogenous mixture. The materials chosen also need to be chemically resistant to the product and propellant and could t~erefore vary depending on the application. Suitable S mixturs~ include HDPE and LLDPE or LDPE, or polyethylene and polypropylene.
The relative quantity of the softer and stiffer plastic materials combined to form the mixture having the characteristics described above depends on their softness -and stiffness. For example, if the soft material and stiff material are each close to the desired hardness and flexural modulus values, mixtures of between about 60% of one to 40%
of the other may be utilized to yield mixtures having the characteristics of hardness and flexural modulus described above. If either or both of the hardness and flexural modulus values of either material are far from the desired values, larger quantities of one material may be required to yield the desired values in the mixture. For example, mixtures of between about 60%-70% of one to about 40%-30% of the other, about 70%-80% of one to about 30%-20% of the other or even greater than 80% of one and less than 20% of the other, may be utilized.
The preferred stiffer material is HDPE having a flexural mcdulus of at lsast about 140,000 psi. A higher flexural modulus is even more preferred. The preferred HDPE is Altav n~ 6200B HDPE, available from Plastics Del Logo, C.A.
Venezuela. Preferably, the LLDP~ has a hardness no greater WO93/12901 ~ PCT/US92/111 2 ~ 30 3r~Z -16-than about 55 and more preferably no greater than about 50.
The prefQrred LLDPE is DNDA-7340 Natural 7 (~DNDA-7340~), available from Union Carbide.
Typical property data for the preferred HDPE and LLDPE
appear below:
Altav~n~ 6200B
Covenin ASTM Typical Properties Method Method Value Melt Index 1552 D 1238 0.40 g/10 min Density - D 1505 0.0958 g/cm3 Yield strength 1357 D 638 280 Kg/cm2 Tensi}e strength at break 1357 D 638 320 Kg/cm2 :Elongation at break 1357 D 638 >500%
-~ Izod Impact strength 822 D 256 12 Xg. cm/cm ; Environmental cracking resistance - D 693 >400 hours Flexural Modulus 1% Secant D 790 . 145,000 Hardness D 2~40 ~66 Propertv Test Method ~vpical Values Melt Index D 1238 0.8 g/10 minutes Density D 1505 0.920 g/cm Flexural Modulu~
.1% Secant D 638 34,000 psi;234 Mpa Tensil~ Strength D 638 2,250 psi:l5.5 Mpa ,~ .
W093/12901 2130352 PCT/US92/111~
--17-- ~,, 1', tr ! X~;
DNDA-73~0 ~oont~) Property Test Nethod Typical Values s Ultimate Elongation D 638 500 %
Bent Strip Craek Resistanee, hrs~X~ F
100% ~Igepal~ D 1693 >500 10% ~Igepal~ >soo Brittleness Temperature D 746Below -lOO-C
Flex. Life, Cyeleæ
to Fail UCC Method 140,000 20Minimum Shear Rate To Melt Fraeture, see~1 UCC Nethod 4,000 Hardness D 2240 -45 With the preferred HDPE and LLDPE described above, mixtures within the range of about 62%-52% LLDPE to about 38*-48% HDPE are preferred. A mixture of 57% by weight of the DNDA-7340, 43% by weight of the Altaven~ 6200B, is eurrently being used.
Alternatively, a soft material, such as LLDPE, can be stiffened, increasing its flexural modulus by the addition of inorganic filler or fiber. Fiberglass fiber, glass beads, talc, or calcium carbonate are suitable additives.
Coupling agents may be required to bond the inorganic filters to the organie base material, as is known in the art.
In eertain applieations, sueh as where propellant is inserted into the eontainer at high pressure after the produet has been-inserted, an adhesive is preferably used to W093/12901 ~ $ PCT/US92/1t184 further secure the gasket of the invention to the mounting cup If the gasket is of the sleeve type, applied in accordance with the proceæs of the '525 and '948 patents, it is further preferred to use a thermal adhesive The thermal adhesive prevents the gasket from prematurely bonding to the mounting cup, preventing its advancement into its final position partially within the channel 20 of the mounting cup lO Heating of the mounting cup prior to the final advancement of the gasket in the gasket placement process melts the thermal adhesive, activating the adhesive After the gasket is advanced and the mounting cup is removed from the h at ourc-, the temp-rature of th~ mounting cup drops to room temperature and the thermal adhesiv~ bonds the gasket to the mounting cup Pr~f~rably, tho adhe~ive is a mlxture Or about 64 67%
Exxon Escor acid terpolymer ATX 325 (~ATX 325~), about 35 67% DNDA-7340 and O 66% H Xohnstamm PB 3962 blue dry colorant The blue colorant is added to enable the visible inspection of the sleeve gasket to determine if the adhesive is evenly distributed It also eases identification of the gasket on the mounting cup The thermal adhesive layer is preferably about 0 00075 inches thick Typicai property data for ATX 325 appear below AT~ 325 25PROPERTIES TM METHOD VA~UES
Molt Ind~x D 1238(E) 20 - g/10 ~ln , ;, ~ .
93/12901 2~30352 PCT/USg2/11184 -19- ~a`~
ATX 325 (cont~
PROPERTIES ~STM METHOD VALUES
Acid Number Exxon Method 45 Milligrams KOH/gm polymer Density ~ ~ 792 0.942 10 g/cc Tensile Strength D 638 1200 psi (MPa) (8) 15Elongation % D 638 ~Compression Molded Type IV specimens, crosæhead speed 2 in/min (5.1 cm/min)) 1800 Flexural Modulus D 790 1300 psi (MPa) (9) Tensile Impact, D 1822(S) 25ft-lb /in2 (XJ/m2)~
73-F (23-C) 350 (735) -43-F (-40-C) 255 (535) Hardness, Shore D D 2240 21 DSC Melting Point D 3417 149 (65) F (-C) Viscat Softening Point D 1525 140 (60) F (-C), 200 g load (Rate B) To form the preferred gasket of the invention, about 57%
by weight of DND~-7340 LLDPE and about 43% by weight of Altaven~ HDPE 6200B were added to a lD Banbury Mixer with a capacity of 30 pounds and mixed for about 2.5 minutes. Such a mixQr i~ available from Farrel Machinery, for example.
The mixing ~tarted at room temperature and reached 380-400-F by the end o~ the mixing period. The mixture wa~ then conveyed to a Farrel 4t inch extruder, preh-ated to about WO 93/12901 r ~ PCr/US92/1 1 184 2i3035Z
400-420F. The mixture was discharged from the extruder at a rate of about 600 pounds per hour to a cooling trough and a Cumberland Strand Pelletizer, available from Cumberland, Inc. The pelletized mixture was later converted into a - 5 sleeve gasket by extrusion, as is known in the art. The sleeve gasket should be visually inspected to ensure that the gasket thickness is uniform. Thinned areas of the sleeve can interfere with the integrity of the seal, causing displacement of the gasket prior to clinching, or leaks.
~;~ 10 To form the preferred thermal adhesive, about 64.67% by weight of ATX 325, about 35.67% by weight of DNDA-7340 LLDPE
and O.S5% by weight of H. Xohnstamm PB 3962 blue colorant were ~dded to the Banbury mixer and mixed for 2 minutes, up to 300-320-F. The mixture was then conveyed to an extruder and extruded at a rat~ of about 600 pounds per hour at between 300-320'F. It was then pelletized as above. The thermal adhe~ive and sleeve gasket were coextruded into a tool where the layers were merged, as is known in the art.
The gasket material wa~ approximately 0.014 inche~ thicX
while the layer of thermal adhesive, which is located on the inside surface of the sleeve gasket material, was approximately 0.00075 inches thick. The sleeve gasket should be visually inspected to ensure that the thermal adhesive has been applied evenly.
The gasket of the invention i~ prefer~bly positioned on the mounting cup a8 g~n rally de~cribed in the '525 and '948 patents. a singl~ station gagket ~ounting cup assembly ~:' W~93~12901 2130352 PCT~USg2/~
machine is utilized instead of the six station assembly machine shown in Figure 3 of the '948 pat~nt It has been found that the sleeve gasket material may be positioned on a single mounting cup faster and more accurately than if - 5 sleeve gasket material is concurrently positioned on BiX
mounting cups In addition, higher temperatures are curr~ntly used than those disclosed in thQs~ patQnts A mounting cup temperature of at least about 150 F and pr~f~rably about 170 F, a- m asurod o~ th- rac-way about l foot from the punch station, les~ than one second after the final positioning of the gasket within the channel of the mounting cup, is utilized This is a convenient point to measure the temperature It is believed that the temperature of the mounting cup is 20 - 30 F higher while the gasket is being advanced to its final position on the mounting cup At 170 F, the gasket's increased pliability further eases its advancement into the channel of the cup, as does the wetting provided by melting the thermal adhesive At higher temperatures, the gasket could degrade and become too soft However, mixtures including higher percentages of HDPE can tolerate higher temperatures A one piece punch 30 is preferred for advancing the gasket 24 into the channel 20 of the mounting cup The - punch preferably includes an exten~ion 30a for engaging th~
end o~ tb- first portion 24a of th gasket 24 as it is being adv~anc~d into the cbann~l 20 of th- mounting cup lO as shown in Figure 3 The xtension 30a ensures that the gask t is .
WO 93/12901 ! `' ~ PCI/US92/11184 2~30352 -22-advanced to its preferred position within the channel 20 of the cup, yielding the preferred gasket flare d, as shown in Figure 1. A shoulder 34 is provided to engage the top of the second portion 24b of the gasket 24 and to advance the gasket to its final position. The punch further includes a series of lugs 32 formed by pins 32a pressfit into the punch 30. These lugs form the dimples 26 shown in Figure 1 and ~described further in U.S. Serial No. 07/814,370. Eurther details concerning the process and preferred puncb utilized -in manufacturing the gasketed mounting cup of the present invention are described in U.S.S.N. 07/814,370.
Comparative tests of the gasket in accordance with the preferred embodiments of the present invention with con~entional gaskets of LLDPE have ~;hown that the gasket of the present invention i~ more resistant to blown gasket failure and has more consistent performance. The forces applied to a gasket in the channel of th~ mounting cup during undercap filling were simulated by a bench device comprising a fixture shaped like a container bead positioned within an airtight chamber. The mounting cup WZIS placed on the fixture and a cap E~eal, pres~ure loaded by an air cylinder, was pressed down on the mounting cup with an adjustable force. Air was pumped into the chamber at a desired pressure. When the pressure within the chamber overcame the force exerted by the air cylinder Imd cap seal on the mounting cup, th mounting cup rose. Air then passed between th~ channel of the mounting cup and the fixture, , ~
W093/12901 ~30352 PCT/uS92/~
-23- ~ t past the gasket, just as propellant is forced through the channel into a container during undercap filling.
12 gaskets are considered a representative test sample.
The maximum pressure where none of the 12 test gaskets failed (~Pl~) and the minimum pressure that caused all 12 to fail (~P2~) were det~rmin~d. A failure is a blown gasket.
A higher Pl indicates better resistance to blown qasket failure while a ~mall difference between Pl and P2 indicates consist~nt product porformanc~. The pre~sur~ of the cap ~eal wa~ varied ~uoh that if all 12 ga~kets did not pa~s the tost, the pre~ure was lower~d. If all 12 p~ d, th-pressure was raised until Pl was determined. Then the pressure was increased until all 12 gaskets failed. Pl and P2 can be converted into load forces by multiplying the lS pressure values in the air cylinder providing the force against the cap seal, by 12.5, which is the approximate area of the cylinder in inches.
For gaskets of LLDPE, adhered to the mounting cup by the thermal adhesive described above, at a filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 = 28 psi (350 lbs).
At a fillinq pressure of 800 psi, Pl = lO psi (125 lbs) and P2 = 24 psi (300 lbs).
For gaskets of Altaven~ 6200B and DNDA-7340 of 43$ and - 57%, respectively~ bonded to th~ ~ounting cup by the th~rmal adhe~lv~ de~cr~b d a~ ve, at a filling pro~ure of 600 p8i, both Pl and n - 28 p8i (350 lb~). At a ~illing pr~ure of 800 p~i, Pl - 26 p~i (325 lbs) and P2 - 28 p~i (3S0 lb~).
WO93/12901 PCT/US921111~
2~303SZ -24-These results demonstrate that the gasket material of the present invention is far superior to conventional ga6k~ts of ~DPE in resistance to blown gasket failure and in consistency of performance.
Comparative tests varying the cut length of the gasket, which effects the flare diameter of the gasket within the channel of the mounting cup, showed imprQved results as the cut length was increased. For gaskets of a height of 0.225 inches, comprised entirely of LLDPE and adhered to the mounting cup by the thermal adhesive described above, at a filling pressure of 600 psi, Pl s 10 psi (125 lbs) and P2 =
28 psi (350 lbs). At a filling pressure of 800 psi, Pl = 8 ;; psi (100 lbs) and P2 = 26 psi (325 lbs).
- A~ a height of 0.250 inche~, all other variables being the ~ame as above, at a filling pre~sure of 600 psi, Pl 5 14 psi (175 lbs) and P2 3 28 psi (350 lbs). At a filling pressure of 800 psi, Pl = 10 psi (125 lbs) and P2 = 24 psi (300 lbs).
At a height of 0.275 inches, all other variables being the same as above, at a filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 = 28 psi (350 lbs). At a filling pressure of 800 psi, Pl - 12 psi (150 lbs) and P2 = 18 psi (225 lbs).
~omparative t~t~ varying th~ d~sign o~ the punch show~d improved result~ with a one piec~ punch including an extQnsion 30a for engaging the gaaket as shown in Figure 3, ;~ over a two piece punch. For a LLDPE gasket with a cut .
21303S~
-25~ c~;
length of 0.270 inches bonded to the mounting cup by the thermal adhesive described above, and a cup temperature of 154-F, applied with a two piece punch, at filling pressure of 600 psi, Pl = 14 psi (175 lbs) and P2 - 28 psi (350 lbs).
At a filling pressure of 800 psi, Pl z 12 pBi (150 lbs) and P2 = 18 psi (225 lbs).
With the one piece punch of Figure 3, all other variables being equal, at a filling pressure 600 psi, Pl = 16 psi (200 lbs) and P2.= 26 psi (325 lbs). At a filling pressure of 800 psi, Pl = 14 lbs) psi (175 lbs) and P2 = 24 psi (300 lbs).
The preferred characteristics of material, thermal adhesive, cut length and punch design each demonstrated improved resistance to dislodgement and consistency of performance. Taken togather, the preferred characteristics yield a superior gasketed mounting cup.
Claims (41)
1. A plastic polymer for use as a gasket material for sealing a channel of a mounting cup to a bead of a container having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM method D 790 and a hardness no greater than about 60 Shore D as measured by ASTM method D 2240.
2. The plastic polymer of claim 1 having a flexural modulus greater than about 90,000 psi.
3. The plastic polymer of claims 1 or 2 having a hardness of about 56 or less.
4. The plastic polymer of claim 1 wherein the polymer is a thermoplastic.
5. The gasket material of claims 1 or 4 wherein the gasket has a cut length of about 0.250-0.285 inches.
6. The gasket material of claim 1 further comprising a layer of thermal adhesive.
7. A thermoplastic polymer for use as a sleeve gasket material for sealing a channel of a mounting cup to a bead of a container having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM method D 790 and a hardness no greater than about 60 Shore D as measured by ASTM method D 2240.
8. The thermoplastic polymer of claim 7 having a flexural modulus greater than about 90,000 psi.
9. The thermoplastic polymer of claims 7 or 8 having a hardness of about 56 or less.
10. The gasket material of claim 7 chosen from the group consisting of polyethylenes, polypropylenes, polyolefinic compounds, ethylvinylacetate (EVA) copolymers, ethyl vinyl alcohol copolymers, polypropylene and ethylene copolymers, polyethylene modified by elastomers, polyamides, nylon 11, polyurethanes, polyesters, ionomers and polycarbonates.
11. A gasket material for sealing a channel of a mounting cup to a bead of a container comprising a mixture of a first plastic material and a second plastic material mixed in proportion such that the mixture has a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM method D 790 and a hardness no greater than about 60 Shore D as measured by ASTM method D 2240.
12. The gasket material of claim 11 wherein the first material is chosen from the group consisting of HDPE, stiff polyethylenes, polycarbonates, polypropylenes, polyesters, acrylonitrilebutadienstyrenes ("ABS"), and acetyls, and the second plastic material is chosen from the group consisting of soft polyethylenes, soft polyolefins, ethylene-ethyl acrylate copolymer, polyesters, polyurethanes and thermoplastic elastomers.
13. A gasket material for sealing a channel of a mounting cup to a bead of a container comprising a mixture of high density polyethylene and linear low density polyethylene, the gasket material having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
14. The gasket material of claims 11 or 13 having a flexural modulus is greater than 90,000 psi.
15. The gasket material of claims 11 or 13 having a hardness of about 56 or less.
16. The gasket material of claim 13 wherein the high density-polyethylene is in a range of about 38%-48% by weight and the linear low density polyethylene material is in a range of about 52%-62% by weight.
17. The gasket material of claim 13 wherein the high density polyethylene is about 43% by weight of the gasket and the linear low density polyethylene is about 57% by weight of the gasket.
18. The gasket material of claim 17 or 18 wherein the LLDPE is DNDA.
19. The gasket material of claim 17 wherein the HDPE is AltavenTM 6200B.
20. The gasket material of claim 15 further comprising a layer of thermal adhesive.
21. The gasket material of claim 15, wherein the gasket has a cut length of 0.250-0.285 inches.
22. A gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel polyethylene, the gasket material having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
14. The gasket material of claims 11 or 13 having a flexural modulus is greater than 90,000 psi.
15. The gasket material of claims 11 or 13 having a hardness of about 56 or less.
16. The gasket material of claim 13 wherein the high density-polyethylene is in a range of about 38%-48% by weight and the linear low density polyethylene material is in a range of about 52%-62% by weight.
17. The gasket material of claim 13 wherein the high density polyethylene is about 43% by weight of the gasket and the linear low density polyethylene is about 57% by weight of the gasket.
18. The gasket material of claim 17 or 18 wherein the LLDPE is DNDA.
19. The gasket material of claim 17 wherein the HDPE is AltavenTM 6200B.
20. The gasket material of claim 15 further comprising a layer of thermal adhesive.
21. The gasket material of claim 15, wherein the gasket has a cut length of 0.250-0.285 inches.
22. A gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel polyethylene, the gasket material having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
14. The gasket material of claims 11 or 13 having a flexural modulus is greater than 90,000 psi.
15. The gasket material of claims 11 or 13 having a hardness of about 56 or less.
16. The gasket material of claim 13 wherein the high 10 density polyethylene is in a range of about 38%-48% by weight and the linear low density polyethylene material is in a range of about 52%-62% by weight.
17. The gasket material of claim 13 wherein the high density polyethylene is about 43% by weight of the gasket and the linear low density polyethylene is about 57% by weight of the gasket.
18. The gasket material of claim 17 wherein the LLDPE is DNDA.
19. The gasket material of claim 17 wherein the HDPE is 20 AltavenTM 6200B.
20. The gasket material of claim 15 further comprising a layer of thermal adhesive.
21. The gasket material of claim 15, wherein the gasket has a cut length of 0.250-0.285 inches.
22. A gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening; and a gasket material disposed partially within the channel of the mounting cup and partially along the skirt of the mounting cup, the gasket comprising a plastic polymer having a flexural modulus, 1% secant, of at least about 70,000 psi as measured by ASTM method D 790 and a hardness no greater than about 60 Shore D as measured by ASTM method D 2240.
23. The gasketed mounting cup of claim 22 wherein the gasket has a flexural modulus of at least about 90,000 psi.
24. The gasketed mounting cup of claims 22 or 23 wherein the gasket material has a hardness of about 56 or less.
25. A gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening; and a gasket material disposed partially within the channel of the mounting cup and partially along the skirt of the mounting cup, the gasket comprising a mixture of a first thermoplastic material and a second thermoplastic material, the first material having a higher flexural modulus than the second, and the second material being less hard than the first, the first and second materials being mixed in proportion such that the mixture has a flexural modulus, 1%
secant, of at least about 70,000 psi as measured by ASTM
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
secant, of at least about 70,000 psi as measured by ASTM
method D 790 and a hardness no greater than about 60 Shore D
as measured by ASTM method D 2240.
26. The gasketed mounting cup of claim 25 wherein the first material is high density polyethylene and the second material is linear low density polyethylene.
27. The gasketed mounting cup of claim 26 wherein the first material is in a range of about 38%-48% by weight and the second material is in a range of about 62%-52% by weight.
28. The gasketed mounting cup of claim 26 wherein the high density polyethylene is about 43% by weight of the gasket and the linear low density polyethylene is about 57%
by weight of the gasket.
by weight of the gasket.
29. The gasketed mounting cup of claim 25 further comprising a layer of thermal adhesive between the gasket and the mounting cup.
30. The gasketed mounting cup of claim 25 wherein the gasket has a cut length of about 0.250-0.285 inches.
31. The gasketed mounting cup of claims 25 wherein the gasket is adhered to the mounting cup by a thermal adhesive.
32. A gasket material for sealing a channel of a mounting cup to a bead of a container comprising a mixture of a first plastic material having sufficient stiffness to maintain the gasket in position partially within the channel of the mounting cup and a second plastic material having sufficient softness to provide the seal.
33. A gasket for sealing a channel of a mounting cup to a bead of a container comprising a mixture of a stiffer thermoplastic material and a softer thermoplastic material.
34. A gasket for sealing a channel of a standard mounting cup to bead of a standard container, the gasket having a cut length of between about 0.250-0285 inches.
35. A standard gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening, the annular channel having a center and a gasket material having a first portion partially disposed within the channel of the mounting cup and a second portion partially disposed along the skirt of the mounting cup, the first and second portions each having an end, the gasket having a length as measured from the center of the annular channel of the mounting cup to an end of the gasket along the skirt of the mounting cup, of at least about 0.150 inches.
36. The gasketed mounting cup of claim 35 wherein the length of the gasket is about 0.175 inches.
37. The gasketed mounting cup of claims 35 or 36 wherein the diameter of the gasket as measured at the end of the first portion of the gasket through a center of the mounting cup is at least about 1.100 inches.
38. The gasketed mounting cup claims 35 or 36 wherein a diameter of the gasket as measured at the end of the first portion of the gasket through a center of the mounting cup is at least about 1.180 inches.
39. The gasketed mounting cup of claims 35 or 36 wherein the diameter of the gasket as measured at the end of the first portion of the gasket through a center of the mounting cup is about 1.200 inches.
40. The gasketed mounting cup of claims 35 or 36 wherein the end of the first portion of the gasket is at about the 10 o'clock position within the annular channel of the mounting cup.
41. A gasketed mounting cup comprising a panel, a skirt integral with and depending from the periphery of the panel, the skirt being outwardly flared to form an annular channel for receiving a container bead that defines a container opening, the annular channel having a center and a gasket material having a first portion partially disposed within the channel of the mounting cup and a second portion partially disposed along the skirt of the mounting cup, the first and second portions each having an end, the gasket having a length as measured from the center of the annular channel of the mounting cup to an end of the gasket along the skirt of the mounting cup of at least about 0.150 inches and a diameter of the gasket as measured at the end of the first portion through a cente of the mounting cup is about 1.200 inches.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81411391A | 1991-12-26 | 1991-12-26 | |
| US814,113 | 1991-12-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2130352A1 true CA2130352A1 (en) | 1993-06-27 |
Family
ID=25214199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002130352A Abandoned CA2130352A1 (en) | 1991-12-26 | 1992-12-23 | Improved gasket for an aerosol mounting cup |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0618848A4 (en) |
| CN (1) | CN1078423A (en) |
| AU (1) | AU3420193A (en) |
| CA (1) | CA2130352A1 (en) |
| GB (1) | GB2262742A (en) |
| MX (1) | MX9207246A (en) |
| PT (1) | PT101150A (en) |
| TW (1) | TW245666B (en) |
| WO (1) | WO1993012901A1 (en) |
| ZA (1) | ZA929464B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102795433A (en) * | 2012-08-31 | 2012-11-28 | 苏州拓维工程装备有限公司 | Normally press and normally open type sealed manhole device with curved surface and folded edge |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3342381A (en) * | 1966-12-20 | 1967-09-19 | Grace W R & Co | Aerosol container closures with plastisol sealing gaskets |
| AU423893B2 (en) * | 1968-10-18 | 1972-05-05 | W. R. Grace & Co | Aerosol container closures |
| US4020966A (en) * | 1975-03-28 | 1977-05-03 | W. R. Grace & Co. | Plastisol composition and container closure gasket made therefrom |
| US4621964A (en) * | 1982-07-06 | 1986-11-11 | Plastic Specialties And Technologies, Inc. | Valve mounting assembly for aerosol containers and the like |
| US4717034A (en) * | 1982-07-06 | 1988-01-05 | Owens-Illinois Closure Inc. | One-piece thermoplastic closure having press-on screw off structure including spaced vertical ribs in the skirt of the closure |
| JPS5914917A (en) * | 1982-07-16 | 1984-01-25 | Japan Crown Cork Co Ltd | Resin cap and manufacture thereof |
| GB8507095D0 (en) * | 1985-03-19 | 1985-04-24 | Grace W R & Co | Sealing composition |
| JPS6320057A (en) * | 1986-07-15 | 1988-01-27 | Toyo Aerosol Kogyo Kk | Formation of gasket of mountain cup for aerosol vessel |
| CA1315217C (en) * | 1987-05-07 | 1993-03-30 | Robert Henry Abplanalp | Aerosol container closure |
| ES2112863T3 (en) * | 1990-07-18 | 1998-04-16 | Precision Valve Corp | MULTILAYER GASKET FOR CLOSING AEROSOL CONTAINER. |
-
1992
- 1992-12-07 ZA ZA929464A patent/ZA929464B/en unknown
- 1992-12-09 GB GB9225688A patent/GB2262742A/en not_active Withdrawn
- 1992-12-14 MX MX9207246A patent/MX9207246A/en not_active Application Discontinuation
- 1992-12-22 PT PT101150A patent/PT101150A/en not_active Application Discontinuation
- 1992-12-23 CA CA002130352A patent/CA2130352A1/en not_active Abandoned
- 1992-12-23 AU AU34201/93A patent/AU3420193A/en not_active Abandoned
- 1992-12-23 WO PCT/US1992/011184 patent/WO1993012901A1/en not_active Application Discontinuation
- 1992-12-23 EP EP93902734A patent/EP0618848A4/en not_active Withdrawn
- 1992-12-24 CN CN 92115376 patent/CN1078423A/en active Pending
- 1992-12-24 TW TW081110355A patent/TW245666B/zh active
Also Published As
| Publication number | Publication date |
|---|---|
| AU3420193A (en) | 1993-07-28 |
| TW245666B (en) | 1995-04-21 |
| EP0618848A1 (en) | 1994-10-12 |
| ZA929464B (en) | 1993-06-10 |
| CN1078423A (en) | 1993-11-17 |
| MX9207246A (en) | 1993-06-01 |
| GB2262742A (en) | 1993-06-30 |
| EP0618848A4 (en) | 1995-05-10 |
| PT101150A (en) | 1994-06-30 |
| GB9225688D0 (en) | 1993-02-03 |
| WO1993012901A1 (en) | 1993-07-08 |
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| FZDE | Dead |