JPS5850634B2 - Thermoplastic can sealant composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealant composition suitable for sealing the end of cans of the type used for food and beverages.

For the manufacture of metal cans for packaging food and beverages, the cone can be constructed from two or three parts.

When constructed in two parts, it is generally a deeply elongated cylindrical part that is closed at one end and is attached during the final step of closing and sealing the can after filling it with food or beverage. It consists of an end member.

In the case of three, it generally consists of a cylindrical crotch portion with an open end and separate top and bottom members of the can, and one of the top and bottom members. is generally affixed to seal one end of the can before filling with food or beverage, and the other end is affixed to close and seal the cone after packaging the desired contents within the end.

Advantageously, these end members of the can can be fastened to the cylindrical body of the can by a double seam operation, but they may also be provided with elongated recesses adjacent to the periphery of the central panel. is common, the outer end of which is formed by an inward fold or hook.

A sealant composition is provided in this elongated depression.

The cone to which the end piece is attached generally includes an outwardly bent flange, or hook portion of the body, adjacent its open end.

To attach the end piece to the cone, place the end member over the open end of the cone such that the sealant composition in the elongated recess mates with the upper side of the hook portion of the body. .

A conventional double seam operation is then performed to distort the end piece and body into a double seam, as is well understood in the iron making art.

In practice, it is common to apply a sealant composition to the elongated recess immediately after the end piece is stamped from the metal stock.

When operating with the three pieces described above, the same sealant composition is usually used from the beginning on both end sections so that the double seams at each end are as identical as possible. .

Of course, the sealant composition serves to protect the contents of the can from contamination and to retain the contents completely within the edges.

In general, the selection of a particular sealant composition will depend on the nature of the article to be filled, but in most cases all such sealant compositions are rubber dispersions formulated for high speed equipment operation. It is based on the body.

Sealant compositions for laid ends are generally classified into two groups: aqueous-based rubber dispersions and volatile organic solvent-based rubber dispersions, the latter being (a) water resistant. (b) oil-resistant and used for packaging of fruits, vegetables, beverages and other types of pet food; (b) oil-resistant and used for packaging of fish, poultry, soups and other food products; It is often divided into what is used for the purpose.

In conventional practice, aqueous-based rubber dispersion sealant compositions are typically dewatered by a separate drying operation, while volatile organic solvent-based rubber dispersions are The body-based end generally dries itself during storage in a workshop or warehouse prior to use, by evaporation of volatile solvent components.

Thus, although sealant compositions using volatile organic solvent-based rubber dispersion sealant compositions have an advantage over aqueous-based compositions in that they do not require a separate drying operation, such volatile The use of organic solvent-based compositions evaporates large amounts of volatile organic solvents into the equipment plant area, creating undesirable environmental pollution as well as fire and health problems.

In a typical day-to-day operation, about 600 drams of volatile organic solvent-based sealant composition are used, with an average solvent content of about 60%.

For example, widely used volatile organic solvent-based rubber dispersion sealant compositions consist of hexane dispersions of SBR and/or butyl rubber, along with inert fillers, colorants, aging stabilizers, and viscosity stabilizers. and edible antioxidants.

The total solids content of such sealant compositions is about 40%, with the remainder being volatile solvent components.

Using this sealant composition, approximately 74.943 liters (approximately 19,800 gallons) of volatile organic solvent per day can be removed.
Assuming the number of actual working days in a year is 250, it is approximately 1892.
The amount will be released into the atmosphere in an amount of 50,000 liters (just under 5 million gallons).

It is clear that it is extremely desirable to reduce the emission of organic solvents as much as possible.

The sealant composition provided by the present invention comprises 100 parts by weight of at least one of natural rubber or synthetic rubber, and -1
Polymerization of a cracked petroleum fraction boiling at 0 to 280°C and containing unsaturated hydrocarbons of which at least 50% by weight is at least one of aromatic olefins, cyclic olefins, and cyclic diolefins, resulting in at least 40% of the resulting polymer 30 to 120 parts by weight of a hydrogenated hydrocarbon resin adhesive produced by hydrogenation to a degree of hydrogenation of about 85 to 12 parts by weight.
about 15-30% by weight of a hydrocarbon resin that melts in the range of 5°C to inhibit creep of the resulting composition; about 1% stearic acid;
~8% by weight; butylated hydroxytoluene approximately 0.1-1
Weight%: Polyparadinitronobenzene 0.1-1% by weight
: Paraffin wax about 20-40% by weight; Zinc oxide about 1-5% by weight; Lamp black about 0.25-1% by weight;
Titanium dioxide approximately 5-15% by weight; molecular weight approximately 1000-6
about 10-30% by weight of polyisobutylene in the range of 000;
and about 10 to 20% by weight of at least one of butyl rubber, styrene-butadiene rubber, and styrene-isoprene rubber (butyl rubber is preferred).

When using styrene-butadiene rubber, it has a Shore A hardness of 60 to 65, but when using styrene-isoprene rubber, it has a Shore A hardness of 35 to 40.

The thermoplastic sealant composition of the present invention is 100% solids and has a specific gravity of 0.925 at about 26.6°C (80"F) and a specific gravity of about 177.6°C (350"F). The maximum viscosity is 10,000 cps, measured at 6 rpm on an A4 spindle on a Brookfield LVF viscometer.

The hydrogenated hydrocarbon resin adhesive used here has a molecular weight of 40.
0~3000. Softening point 60-150'C.

It has a bromine number of 30 or less.

In the hydrocarbon resin used to produce the sealant composition of the present invention, the synthetic rubber components used are styrene-butadiene rubber, acrylonitrile butadiene rubber, polyisobutylene rubber, isoprene-isobutylene rubber, chloroprene rubber, silicone rubber, polyvinyl It may be one of ether and chlorinated rubber.

Hydrocarbon resins can be produced by the method described in US Pat. No. 3,554,940.

The present invention also comprises a metal body portion and at least one metal end closure attached to one end thereof by a double seam and a sealant composition, the composition being encapsulated within the double seam. forming a layer within the seam between the closure and the wall of the metal body portion, and wherein the sealant is provided by a sealant composition as defined above, and wherein the sealant is provided by a sealant composition as defined above; -28,88~65
．． It also relates to metal containers suitable for use in the temperature range of 5°C (-20 to 150'F).

The sealant composition of the present invention can be applied to an elongated recess in the end, whereby the sealant flows under the bend or hook portion by conventional heat melting means.

In this regard, it may be useful to set the positioning end to about 93.3 to 121, for example.
．． When preheated to a temperature of 6℃ (about 200-250℃ below),
It has been found to be advantageous to allow the sealant composition to flow down the bend or hook portion in an efficient manner.

Preferably, the temperature is between about 350 and 375'F when the molten sealant composition is applied to the end, and the end is heated during application of the sealant. may be rotated, for example, at a speed of about 1500 to 3500 rpm.

The hot melt sealant composition of the present invention is ioo% solids;
It has the following properties.

Appearance: Gray solid: 100% Specific gravity at about 26.6℃ (below 80): 0.925 Ash content: 1
1.6% viscosity (Brookfield A4 spindle, 6
rpm) approx. 190.5℃ (375'P) 5800 cp
s approx. 176.6°C (350'P) 8500
cps approx. 162.7℃ (below 325) 11600c
ps This heated and melted composition was heated to a nozzle diameter of 0.02c.
From the hot melt applicator of rrL(o,oogz), approx.
1. Heated to 66℃ (below 250℃) and 3200℃
The end (apply) while rotating at rpm.

The sealant is heated to approximately 375"F and presses approximately 825 psi.
), it maintains sufficient flexibility even at about -28.88°C (-20°C), and even at about 66.6°C (1
Leap-free sealing is provided even at maximum working temperatures of 50'F.

Claims (1)

[Scope of Claims] 1 (a) Essentially 100 parts by weight of at least one of natural rubber and synthetic rubber, boiled at -10 to 280°C, and at least 50% by weight of aromatic olefins, cyclic olefins and Molecular weight 400-3000, softening point 60-60, produced by polymerizing a cracked petroleum fraction containing at least one unsaturated hydrocarbon, which is a cyclic diolefin, and hydrogenating the resulting polymer to a degree of hydrogenation of at least 40%. 150℃
, hydrogenated hydrocarbon resin adhesive with a bromine number of 30 or less 30-1
20 parts by weight of a hydrocarbon resin which melts in the range of about 85 to 125°C, about 15 to 30 weight percent, (b) about 1 to 8 weight percent of stearic acid, (/→ butylated hydroxytoluene about 0.1 ~1% by weight, (→ polyparazine f losobenzene approximately 0.1-1% by weight
(C) Approximately 20-40% by weight of paraffin wax, (C) Approximately 1-5% by weight of zinc oxide, (G) Approximately 0.25-1% by weight of lamp black, <-
y't is present in an amount of about 5-15% by weight titanium dioxide, (S) about 10-30% by weight polyisobutylene, and (v) 10-20% by weight in addition to the rubber present in component (a). , and Shore A
A sealant for end seals consisting essentially of a mixture of butyl rubber having a hardness of 60 to 65, styrene-butadiene rubber and at least one other rubber selected from styrene-isoprene rubber having a Shore A hardness of 30 to 40. a composition which is 100% solid and has a specific gravity at about 26.6°C (below 80) of Q, 925 and a maximum viscosity at about 176.6°C (350'F); A4 spindle of Brookfield LVE viscometer, 6r
A thermoplastic closed-end sealant formulation comprising 10,000 cps as measured using pm. 2. The sealant composition according to claim 1, wherein the sealant is butyl rubber. 3. The sealant composition according to claim 1, wherein the styrene-butadiene rubber has a Shore A hardness of 60 to 65. 4. The sealant composition according to claim 1, wherein the component (N) is a styrene-isoprene rubber having a Shore A hardness of 35 to 40.