US3545643A - Package for highly viscous tacky materials - Google Patents

Description

Q United States Patent 1 1 3,545,643

72] Inventors John J- gg [56] References Cited 1 N figghga wesmem' New Jersey UNITED STATES PATENTS $11 511 0' Oct :18 1967 2,134,166 10/1938 Wilcox 229/14 451 Patented Dec. 8,1970 2,218,027 10/1940 Hatch 229/14(B)UX [73] Assignee Esso Research and Engineering Company 3 23 6/1950 229/3-5X a corporation of Delaware Linda 2,811,408 10/1957 Braley I6I/S1I1C0ne 2,926,829 3/1960 Wilkins l6l/(Silicone) 3,394,388 7/1968 Kuchlin 229/3.5X [54] PACKAGE FOR HIGHLY VISCOUS TACKY MATERIALS Primary Examiner-Joseph R. Leclair 2 Claims 1 Drawing Assistant Exammer.lames R. Garrett Au0rney-Chasan and Sinnock and Jack Matalon [52] U.S.Cl 220/63,

206/84 [51] lnt.Cl 865d 25/14 ABSTRACT: A packaging container for highly viscous low [50] Field of Search 220/63; 1 molecular weight tacky polymers comprising a container hav- 229/14(B), 3,5;206/84; l61/(Si1icone); ing at least one removable end and a removable polymeric 1 17/ l 38.8(F) liner coated with a release agent.

mminum 8l976 3.545643 g INVENTORS yumm PA'I'ENT ATTORNEY PACKAGE FOR HIGHLY viscous TACKY MATERIALS BACKGROUND or lNVENTION Most highly viscous tacky polymers such as low molecular weight polyisobutylene are mixed and packaged hot," e.g. greater than 250 F., so that the material will flow to some extent or at least be pourable. Containers for-these type materials .must be able to withstand the hot packaging temperatures of approximately 200 to 300"F.'and at the. same time permit the contents to be readily removed for final use.

These materials are presently packaged in expensive metal containers which are of much lighter weight than is desired for the product protection and durability since the container must be peeled from the product in use. These containers are generally coated with a release coat which must be manually applied after the can is manufactured and is therefore generally of poor quality.

SUMMARY or INVENTION It has now been found that low molecular weight tacky polymers maybe readily removed from their containers by providing the container with a removable release agent coated inner liner.

muss DESCRIPTION or DRAWING DETA LED nsscrumoN The container of this inventionis' suitable for use for such tacky polymers as polyisobutylene having a Staudinger molecular weight of 8,000 to 12,000, polybutenes having Staudinger molecular weights-of about 3,000 to 6,000, low molecular weight butyl rubbers and halogenated butyl rubbers and like compounds which are normally not pourable at room temperature, but exhibit cold flow at room temperature and are sufficiently tacky to be'removed from conventional containers only with difficult The inner liner should be capable of withstanding hot packaging conditions without degradation or softening to the point of adhering to the polymer being packaged. Various polymeric films have been found to be useful for this purpose. Typical of the types of film which may be used are polyester film and heat stabilized nylon. Preferably, the polymeric film has a thickness of about 0.5 to aboutS mils; more preferably about I to about 3 mils.

A particularly suitable'polyester film is the reaction product of ethylene glycol and terephthalic acid which is known to the trade by the duPont trademark Mylarf' I-Ieat stabilized nylons are well known and are prepared by specially heat treating a nylon film. Illustrative of such heat stabilized nylon films is Allied Chemicals Capran 80.

In order that the polymeric films release properly from the packaged polymer, it is necessary to coat the film with a release agent. Various release agents may be used in the practice of this invention. Preferably, the release agents are silicone fluids having a viscosity of about 10 to about 30,000

centistokes at 77 F preferably about 50 to 1,000 centistokes, most preferably 100 to 500 centistokes. The materials are well known to the art having carbon to silicon linkages such as disclosed in U.S. Pat. Nos. 2,448,756, 2,484,595 and 2,541,137 which are incorporated herein by reference. These polymers have the general structure:

I'll lit ii -Sl-OSl0-Sl0 I l l R: R: R2

wherein R and R are selected independently from methyl and hydrogen wherein either'R, or R is methyl and the other is methyl or hydrogen. Where both R and R are methyl, the fluids are known as dimethyl silicones or dimethyl siloxanes. The hydrogen attached to the silicon is termed a silanic hydrogen.

The silicone fluids of this invention may, if desired, be cured after application to the polymeric film. The fluids may be applied as the neat oil or from a solvent solution. The solvent may be C -C alkanes such as hexane, heptane or 2-ethyl hexane, C to C aromatics such as benezene, toluene or xylene or any of the well known chlorinated solvents such as methylene chloride or chlorobenzene. Generally, the silicone fluid is present in the solvent at about 30 wt. percent.

Where either R or R of the silicone fluid is hydrogen, that is methyl silicone having silanic hydrogens, the fluid is moisture curable below 50 C. in the presence of a catalyst such as dibutyl tin dilaurate, or dibutyl tin di-Z-ethyl hexoate. High temperature cures are accomplished in the presence of catalysts such as zinc octoate.

Where both R, and R are methyl, the fluid may be moisture cured by the addition of a silanol and a catalyst such as an or ganic titanate, e. g. tetra-isobutyl titanate and tetra-Z-ethylhexyl titanate.

The dimethyl silicones are also available as hydroxy ter-- minated polymers which may be cured in the presence of organic titanates without the addition of silanols to the polymer.

Illustrative of the dimethyl silicones are Union Carbide and Carbons L-45 series fluids and General Electric Co.s SF 96 series fluids, both products being available in a wide range of viscosities up to about 100,000 cs at 77 F. Illustrative of silicone fluids having silaniehydrogens are Union Carbide and Carbons L-31 (a silicone fluid having a viscosity of about 35 cs at 77 F.) and Y-4006 fluids and Dow Cornings Dow Coming 23 silicone fluid. The Y-4006 and Dow Corning 23 fluids are supplied as 30 wt. percent neat oil in xylene. Illustrative of the hydroxy terminated dimethly silicones are Union Carbide and Carbons W900 and Y-l480.

It has been found that the thickness of the release agent coating is not critical. However, it is essential that the coating be continuous. For example, a continuous coating whose thickness is in the Angstrom range will suffice, whereas a discontinuous coating of several mils will not release properly.

Though many coated release papers are available on the market, such as silicone coated glassine, silicone coated parchment and silicone coated latex treated stock, and are effective as release surfaces, they are not generally suited for use in the practice of this invention since they become excessively embrittled by the heat history of hot packaging and can be removed only in small pieces;

Surprisingly, it has been found that cellophane is a satisfactory release surface for the purpose of this invention. It is not embrittled by packaging heat history and may be removed from the packaged polymer without the aid of a release agent.

The cellophane may be removed from the packaged polymer by wetting with water. The water breaks the bond between the polymer and the cellophane, and the cellophane, having sufficient cohesive strength, is'removed in one piece. Preferably, the cellophane film is about 0.5 to about 5 mils in thickness, more preferably about 1 to about 3 mils.

The term cellophane as used in this specification and claims means films produced from wood pulp by the viscose process, known in the trade as uncoated type" cellophanes.

Illustrative of suitable cellophane films are the cellophanes known to the trade as type PD, type PUD and type PUD-O cellophanes which are available from E. I. DuPont de Nemours and Co.

Although other release papers have been found to be not generally suitable for use in the practice of this invention, it has surprisingly been found that clay coated kraft paper having a basic weight of at least 50 lbs./ 1,000 ft.*, coated with finely divided mica, is a suitable release surface for the purposes of this invention. Preferably, the clay coated kraft paper has a basic weight of about 50 to about 100 lbs/1,000 ft The finely divided mica should have a platelet shape with a thickness of about 20 to about 200 Angstroms and about 100 times thickness in diameter. Preferably, the mica is a synthetic mica. synthetic mica is a flourine derivative of phlogopite made by treating potassium flurosilicates with alumina under pressure and heat or by melting basic oxides, fluorides and feldspar together.

Illustrative of the synthetic mica coatings which may be used is a product known in the trade by the Minnesota Mining & Manufacturing Co. trademark "Burnil Brand Microplates. Bumil" Brand Microplates are extremely thin platelets of synthetic mica. The average particle size is about 20l00 Angstroms in thickness and about l times thickness in diameter. The platelets have a melting point of 1800 F., a density of 2.7 g/cc and a refractive index of 1.5.

The term container as used throughout this specification is intended to mean any suitable container having vertical sidewalls and at least one end which can be removed or opened. Illustrative of the container materials which may be used are fiber board, corrugated boxes, metal drums and the like.

In one embodiment of this invention, a covered metal can may be supplied with a Mylar bag internally coated with a silicone release agent, the release agent coated Mylar bag being placed into the container and filled with the tacky polymer. The top of the bag is then tied and the cover put in place. When the polymer is ready for use the container is opened, the inner bag and contents removed from the container and the polymer is stripped of the Mylar bag.

In its preferred embodiment, shown in the drawing, the container comprises a cylindrically shaped body, 1, having two removable ends, 2, 3, equipped with an inner liner release surface, 4. The removable ends are preferably of metal and coated with a silicone release agent. The inner liner release surface is formed in the shape of a cylinder and several inches longer in length than the container itself, e.g. 3 to 4 inches longer. Preferably, the inner liner is a waterproof cellophane or a silicone coated Mylar film. The container body, 1, itself must be smooth walled and have no inner lips. The cylindrically formed inner liner, 4, is inserted into the cylindrical container body, 1, and folded back, 5, over the container edges, 6. One removable cylinder end is put in place. The container is then filled with polymer and the remaining removable end put in place and sealed by means of tape, plastic or metal straps and the like.

It is readily evident from the above description that the need for a separate container liner may be obviated by constructing the container of heavy kraft paper (e.g. 200 lbs/1,000 ft?) which has been coated with synthetic mica. The container may be readily cut away to remove the contents.

For example, conventional fiber drums may be made having their inner surface coated with synthetic mica. Preferably, the coating will be accomplished prior to construction of the drum. Altemately, a light weight (i.e. 50l00 lbs/1,000 ft?) clay coated kraft paper may be glued to the inside of the fiber drum after it has been rolled and removed from the mandrel during manufacture. If desired, the mica maybe applied to a finished drum by slush coating using a slurry of synthetic mica having about 5 to about 25 wt. percent solids.

The weight of the drum wall will be a function of the size of the container using conventional shipping guidelines. For example, a 15 gallon fiber drum having a lbs. net weight limit would be constructed of a five ply kraft paper wall having a bursting strength of 500 lbs.

While the foregoing description and accompanying drawing illustrate a preferred manner of employing this invention, many different embodiments may be made without departing from the spirit and scope thereof and it is to be understood that the present invention is not limited to the specifically disclosed examples thereof.

We claim:

1. A packaging container for tacky materials which comrises:

a. a smooth walled cylindrical container having two removable ends, said ends being coated on their inner faces with a silicone release agent selected from the group consisting of dimethyl silicones, methyl silicones containing silanic hydrogens and hydroxy terminated dimethyl silicones, wherein said silicone release agent has a viscosity at 77 F. of about 10 to about 30,000 es; and b. a cylindrical inner liner substantially longer then the cylindrical container, said inner liner being formed from a material selected from the group consisting of (1) a polymeric film wherein said film is heat treated nylon or a polyester film which is the reaction product of ethylene glycol and terephthaiic acid, said liner being coated internaily with a silicone release agent selected from the group consisting of dimethyl silicones, methyl silicones containing silanic hydrogens and hydroxy terminated dimethyl silicones, wherein said silicone release agent has a viscosity at 77 F. of about 10 to about 30,000 centistokes, (2) a clay coated kraft paper having a basic weight of at least 50 lbs./ l ,000 ft. said paper being coated with a finely divided mica, and (3) uncoated cellophane.

2. The packaging container of claim 1 wherein the inner liner is heat treated nylon and the silicone release agent has a viscosity of about 50 to 1,000 cs.

Images