Aerosol dispenser valve

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 11/228,000 filed Sep. 15, 2005, now U.S. Pat. No. 7,984,834 issued Jul. 26, 2011, and claims the benefit of U.S. Provisional Application No. 60/627,850, filed Nov. 15, 2004, and claims the benefit of U.S. Provisional Application No. 60/610,282, filed Sep. 16, 2004, the entire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to aerosol dispenser valves for products, and in particular to dispenser valves for moisture-curable products such as foams.

Moisture-curable products, such as moisture-curable polyurethane foams, have found wide applications in homes and businesses. These foams are excellent fillers and insulators. The foams are often packaged in aerosol cans with a polypropylene dispenser valve. A problem with these valves is that moisture can migrate through the valve and into the aerosol can. Once inside, the moisture cures the foam, and impairs the function of the valve. The problem is exacerbated if the can is not stored upright, so that the contents of the can surround the valve member. The migration path is shorter, and when the foam cures around the valve member it interferes with the operation of the valve, sealing it closed.

SUMMARY OF THE INVENTION

A preferred embodiment of the present invention is a dispenser valve for a moisture-curable foam made from a glass-filled polyolefin. In the preferred embodiment the polyolefin is a high density polyethylene. The polyethylene preferably has a glass content of between about 2% and about 40%, and more preferably between about 10% and about 30%, and most preferably between about 15% and about 25%. The valve member of the preferred embodiment is more resistant to failure from moisture infiltration than the polypropylene valve members of the prior art. The valve member of the preferred embodiment is less adhesive than the propylene valve members of the prior art, so that to the extent the contents of the container does inadvertently cure inside the container, it is less likely to adhere to the valve member and interfere with the operation of the valve. Thus embodiments of valves in accordance with the principles of this invention can extend the shelf life of urethane foams and other moisture-curable or moisture affected products dispensed from aerosol cans.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross sectional view of a dispenser valve for an aerosol can in accordance with the principles of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of a dispenser valve constructed according to the principles of this invention is indicated generally as 20 in FIG. 1. The dispenser valve 20 comprises a valve member 22 in a seal 24. The valve member 22 has first and second ends 26 and 28, and a central passage 30 extending partially therethrough. A plurality of openings 32 extend through the valve member 22 and communicate with the central passage 30. The openings are covered by the seal 24, but when the valve member 22 is deflected, it opens a space between the valve member 22 and the seal 24, so that the pressurized contents can exit the container between the valve member 22 and the seal, through the openings 32, and out the passage 30.

In accordance with the principles of this invention, the valve member 22 is made from a glass-filled polyolefin. The inventors believe that glass-filled polyethylene is more resistant to adhesion than the polypropylene valve members of the prior art, or other suitable polymer materials.

The inventors have also discovered that chemically coupled glass-filled polyolefin, and specific glass-filled polyethylene is less adhesive than the valve members of the prior art, to the extent that the foam does inadvertently cure inside the container, it is less likely to adhere to the valve member and interfere with the operation of the valve.

The polyethylene is preferably a high density polyethylene. The polyethylene preferably has a glass content of between about 2% and about 40%, and more preferably between about 10% and about 30%, and most preferably between about 20% and about 30%.

Thus the valve member of the preferred embodiment is more resistant to moisture infiltration, and less adhesive to moisture curing foams, such as polyurethanes. Thus the valves constructed in accordance with the valve members of this invention are less likely to fail, even when the cans on which they are used are not properly stored, and provide a greater product shelf life.

EXAMPLE 1

Cans of moisture-curable polyurethane foam components were prepared with valve parts made of different plastics. The cans were stored upside down at an ambient temperature and 90-100% relative humidity. Each week three cans of each type were examined and rated on whether the can was fully functional, stuck but functional, or stuck. Failure was determined when all three cans of the sample failed. The results of the test are given in Table 1.

TABLE 1
20% glass-	Impact
filled	modified			Internally Lubricated
polyethylene	propylene	Polypropylene	Acetal	polypropylene
No failure	Failure	Failure after 5	Sticking	Sticking after 5
after 16	after 5	weeks.	after 7	weeks; failure after
weeks.	weeks.		weeks;	6 weeks
			failure
			after 9
			weeks

EXAMPLE 2

Cans of moisture-curable polyurethane foam components were prepared with valve parts made from different plastics. Sixteen cans of each type were stored upside down at 120° at 80% relative humidity for 11 weeks. Cans were inspected at the end of 11 weeks to determine whether the valves were stuck or were functional. The results are given in Table 2.

TABLE 2
		Number of
		stuck	% of stuck
	Plastic	valves	valves
	50% polyethylene and	0	0%
	50% polyethylene with
	20% glass
	100% polyethylene	2	12.5%
	with 20% glass
	90% polyethylene-	3	18.8%
	10% polypropylene
	with 30% glass
	75% polyethylene-	3	18.8%
	25% polypropylene
	with 30% glass
	100% polypropylene	4	25%
	50% polyethylene-	5	31.3%
	50% polypropylene
	50% polyethylene-	5	31.3%
	50% polypropylene
	with 30% glass
	100% polyethylene-	6	37.5%
	90% polyethylene-	6	37.5%
	10% polypropylene
	75% polyethylene-	10	62.5%
	25% polypropylene

This test shows that valves made of glass filled polyethylene (from 10% to 20%) had the lowest number of stuck valves.

EXAMPLE 3

Cans of moisture-curable polyurethane foam components were prepared with large valve parts made from different plastics. Twenty-two cans of each type were stored upside down at ambient with caps filled with water. Two cans of each type were tested periodically, and it was noted whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. The results are given in Table 3.

TABLE 3
	20% glass-
	filled
	polyethylene	Polypropylene	Acetal
	No failure	Stuck but broke	Stuck but broke free,
	after 22	free, after 18	after 13 weeks-
	weeks.	weeks.	failure after 22
			weeks

EXAMPLE 4

Cans of moisture-curable polyurethane foam components were prepared with small valve parts made from different plastics. Twenty-two cans of each type were stored upside down at ambient with caps filled with water. Two cans of each type were tested periodically, to determine whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. The results are given in Table 4.

TABLE 4
20% glass-	Impact		Ethylene
filled	Modified		Telefluorethylene
polyethylene	Polypropylene	Acetal	polymer (ETFE)
No sticking	Failed, after 8	Stuck but broke	Failures after 19
or failure	weeks.	free, after 12	weeks
after 22		weeks; failure,
weeks.		after 17 weeks.

EXAMPLE 5

Cans of moisture-curable polyurethane foam components were prepared with valve parts made from different plastics. Cans of each type were stored upside down with caps filled with water at 130° F. (to accelerate sticking of the valves). Two cans of each type were periodically tested to determine whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. The results are given in Table 5.

TABLE 5
	20% glass-
	filled
	polyethylene	Polypropylene	Acetal
	No sticking or	Stuck but broke	Stuck but broke
	failure after 51	free after 14	free after 14 days;
	days.	days, failure	failure after 37
		after 35 days.	days.

EXAMPLE 6

Cans of moisture-curable polyurethane foam components were prepared with valve parts made from different plastics. Cans of each type were stored upside down with caps filled with water at 130° F. (to accelerate sticking of the valves). 20% glass filled polyethylene was compared with impact modified propylene for two different neoprene seal materials. Two cans of each type were periodically tested to determine whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. Failure was determined when both valves tested stuck or failed. The results are given in Table 6.

TABLE 6
Seal 1	Seal 2

20% glass-	Impact	20% glass-	Impact
filled	Modified	filled	Modified
polyethylene	polypropylene	polyethylene	polypropylene
No sticking	Failure after	Failure, after	Failure after
or failure	11 days.	21 days.	11 days.
after 23
days.

This testing indicates that glass-filled polyethylene provides improved performance with different seal materials.

EXAMPLE 7

Cans of moisture-curable polyurethane foam components were prepared with valve parts made from different plastics. Cans of each type were stored upside down with caps filled with water at 130° F. (to accelerate sticking of the valves). 20% glass filled polyethylene was compared with propylene and with a conventional valve using a stick resistant coating on the seal. Two cans of each type were periodically tested to determine whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. The results are given in Table 7.

TABLE 7
			Polypropylene
	20% glass-		with stick
	filled		resistant seal
	polyethylene	Polypropylene	coating
	Stuck but	Stuck but	Stuck but
	broke free	broke free	broke free
	after 30	after 22 days;	after 22 days;
	days; no	failure after	failure after
	failure at 36	28 days	30 days
	days

This testing indicates that glass-filled polyethylene continued to function after conventional valves and conventional valves with lubricated seals, failed.

EXAMPLE 8

Cans of moisture-curable polyurethane foam components were prepared with gun valve (vertically opened) parts made from different plastics. Sixteen cans of each type were stored upside down at 130° with caps full of water. Two cans of each type were tested periodically, and it was noted whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. Failure was determined by sticking or failure of both cans. The results are given in Table 8.

TABLE 8
		First	First
	Plastic	Sticking	Failure
	100% polyethylene	—	—
	with 20% glass-filled
	polyethylene (ribbed
	for extra strength)
	Impact Modified	10 days	—
	Polypropylene co-
	polymer (ribbed for
	extra strength)
	Polypropylene	13 days	55 days
	Acetal	10 days	33 days
	Impact Modified	13 days	33 days
	Polypropylene
	Polyethylene	—	26 days*
	75% polyethylene-	10 days
	25% polypropylene
	50% polyethylene-	10 days
	50% polypropylene
	100% polyethylene	—	—
	with 20% glass-filled
	polyethylene
	Impact Modified	10 days
	Polypropylene
*stem failure due to weakness of material

This testing shows the superiority of glass filled polyethylene in both ribbed and unribbed configurations.

EXAMPLE 9

Cans of moisture-curable polyurethane foam components were prepared with gun valve (vertically opened) parts made from different plastics. Twelve to fourteen cans of each type were stored upside down at 130° with caps full of water. Cans of each type were tested periodically, and it was noted whether the valve worked, whether the valve was stuck but broke free, or whether the valve failed. Failure was determined by sticking or failure of both cans. The results are given in Table 9 below, which shows that some standard valves first stuck after only six days and the standard valves were stuck after 11 days, as compared to the valves with 20% glass-filled polyethylene valve components which were not stuck after 20 days of testing. All of the 20% glass-filled polyethylene valve components performed longer than the standard components. The plastic used is a 703 CC chemically coupled 20% glass filled polyethylene available from RTP company, having an impact strength (notched) of about 2.5 ft. lbs./inch and a water absorption of about 0.04 percent.

TABLE 9
			Valves
	Plastic	First Stuck	stuck
	100% Polyethylene with	none of 14	no samples
	20% glass-filled stems	samples	stuck after
		stuck	20 days
	Impact Modified	samples	12 samples
	Polypropylene co-	first stuck	stuck w/in
	polymer (ribbed for	w/in 6 days	11 days
	extra strength)

In the testing conducted, a glass filled polyethylene was always the best performer, and only one other material—Acetal—approached the performance of the glass-filled polyethylene in certain circumstances. Glass-filled polyethylene valve stems show surprisingly superior resistance to sticking (i.e. longer times to initial sticking, and longer times to valve failure) over valve stems of other materials in a variety of environments, different valve sizes, and different sealing materials. Glass-filled polyethylene even showed superior resistance to sticking than conventional valves with available stick resistance coatings.

While the description of the preferred embodiment and the examples and tests focused primarily on moisture-curable foams, and more specifically moisture-curable polyurethane foams, the invention is not so limited that the valves and containers with valves of the present invention can be used with other moisture-curable products that are dispensed from aerosol cans, and even with products that are not moisture-curable, but adversely affected by moisture infiltration.