DE1066686B - Sealing compound based on a polyvinyl chloride resin for the production of a sealing ring - Google Patents

Description

The invention relates to improved sealing compounds in the form of permanent rubber-like gels for the production of a sealant which is composed of polyvinyl chloride resins and for the production a sealing ring z. B. to be used on screw caps, so that after sealing of glass containers with the same to open a certain adjustable torque required is. In particular, the invention is directed to the creation of a lubricating coating or film on the sealing surface of the sealing ring located on the inside of the closure cap or Lining material. This coating or film serves to reduce the coefficient of friction between the sealing ring and that part of the container with which it is in contact. the The lubricity of such a coating determines the amount of torque required to loosen and Removal of the lid from the container is required and prevents the sealant from sticking on the surface of the container after using self-actuating sealing machines known per se done, placing the lid on the container.

The sealant according to the invention finds z. B. Use with screw-on sealing caps, the inside of which is provided with sealing compound. The sealant can be in the form of an annular Side seal or in the form of corner seal rings can be used, or they can take the form have a thin, even coating that extends over the entire inside of the lid.

Those accessible to the improvement according to the invention, from polymers or copolymers of the vinyl chloride existing sealants belong to various types known per se, which have already served to achieve a seal between lids and containers. Copolymers of this type are z. B. vinyl chloride-vinylidene chloride resins and vinyl chloride-vinyl acetate resins. From these copolymers Produce sealing compounds according to various methods known per se. The invention Masses can be extruded, cast and calendered as well as organols. The present Such sealing compounds used are made from paste-forming mixtures of resin and plasticizer produced, which preferably also contain a filler.

However, the same have disadvantages in that the mass at different temperatures has different elasticity. Furthermore, masses of this type give under pressure even in the cold after. These two physical properties inherent in such sealants make it technical Sealant based

a polyvinyl chloride resin
for the production of a sealing ring

Applicant:

Continental Can Company, Inc.,
New York, NY (V. St. A.)

Representative: Dipl.-Ing. L. Hirmer, patent attorney,
Berlin-Halensee, Katharinenstr. 21

Claimed priority:
V. St. v. America April 1, 1957

Donald Henry Zipper, Elmhurst, 111.,
and Harold William Unger, Mt. Prospect, 111.

(V. St. Α.),
have been named as inventors

difficult, if not at all impractical, to provide lids to glass containers with these Ordinary gaskets are fitted without the lids being too loose either, making them not tight close, or put on too tightly so that they stick to a certain extent and only through application an excessively large torque can be removed.

In order to achieve a hermetic or other seal, there must be sufficient friction it prevents the rotatable cap from rotating in the ordinary handling or loosens.

It has been found that the friction developed by sticking between sealants of known type and glass surfaces in the course the time spent standing increases significantly. As a result, the torque can be several times greater may be required to break the seal between the lid and the container. Certain lids were already within 5 to 10 seconds of locking Torques of 3.5 to 32.25 cmkg required to open. After just 1 hour, this amounts to open the required torque sometimes up to 92 cmkg. After even longer times you need to Opening torques of 115 cmkg or more. As has emerged from these measurements,

909 637/393

I 3 4

were the values of the ^1st , after closing to establish between the lid and the container and

open to maintain the required torques extremely fluctuating.

kend and difficult or not at all under control Another purpose of the invention is to bring creation. For the average consumer, an improved sealant should be of the type of the ideal torque required to open such a screw connection, known paste-forming mixtures of resin, regardless of the torque and plasticizer with a contained therein, which elapsed after the container was closed individual particles existing filler, the VerZeitspanne is in a range substantially below improvement in the addition of a lubricant cmkg lie, 115 the ^size:. of the cover influences the which is wherein after the plasticizing and AbGröße of opening required torque, io cool the mixture. The rubber-like gel that arises and, in the case of larger lids, is gaining in importance the correct single gel or, after the mixture has been converted into a regulation of the torque required for opening, permanent rubber-like gel by extrusion same is located. The compounds, the compositions of which are given below, form a lubricant on the sealing surface of the to be given, within the scope of the invention, a gel-converted sealing compound produces a friction coating and a large lid with a diameter of 77 mm which were then screwed tightly onto canning jars on containers with the one provided with the sealing compound. Here, even after long lay the cover removing the cover using the storage times required for opening a maximum of a determined adjustable torque permitted, painting W ^T erte for the torque considerably below 20 A sealant of polyvinyl chloride resin of 115 cmkg. type described above is in the form

It has turned out to be. The use of this known seal of a solidified, paste-forming mixture of resin processing masses has proven to be practically impracticable, and plasticizer, which in uniform defense between the sealing ring and the belly contains finely divided individual particles of a filler and as a result of the sudden return of the elastic To keep individual particles of a paste-forming plasticity of the plastisol developing resin in suspension in a non-volatile softening on cooling. Until the youngest makers for the resin contains. At a temperature time, no method or sealant below the plasticizing temperature of the resin was known for such sealing, of containers with plasticizer component, the resin forms with the lids that the lids form a paste from the containers while it is heated by action of torques within to the plasticizing temperature in the soft half of the specified, relatively limited maker goes into solution. Have a mass of this type unscrewed ver size range. The adhesive strength changes at the plasticizing temperature for already in the first minute after the resin softener mixture to develop into a permanent gel, to close in the heat, while the 35 which is elastic when it cools down, and somewhat rubber-like when it is closed in the cold will,
is longer. . If you now put these sealants of the stand

It is the aim of the invention, improved sealing technology to propose certain lubricant-forming constituent masses which, according to the part, are plasticized on the sealing surface in the formation of the gel after application to the inside of a closure cap 40 known type and after unscrewing the ■■. the mass a lubricant is available, and this lid on a container with the help of the lubricant lining is also able to lubricate the friction-sealing automatic locking devices between the sealing ring and the glass top, the material of the sealing ring and the surface or other sealing surface. 'Containers have a friction seal of controlled 45. The extent of this lubrication is such that an order of magnitude can arise, which can be used to prevent loosening or closure without regard to the sealing ring required to loosen the lid after closure The adhesive strength exerted on the sealing surface is present, but on the other hand, compression forces can be overcome at any time by using a torque of a relatively low torque between the sealing ring and the frictional forces existing between the sealing ring and the frictional forces within a previously determined, relatively narrow area, within an acceptable range. Furthermore, it is of little order of magnitude easily overcome the aim of the present invention to provide a seal. The lubricant forms an intermediate mass of polyvinyl chloride resin masses, a layer which, after the full regression of the compressive force exerted by normal resin sealing ring in the known use for elasticity and the consequent adhesive strength of regular resin sealing ring has, wherein the see between the lid of the sealant and the container existing and container developing friction remains in such a way. In order to unscrew the lid from the container is determined that ^: the lid at any time, one only needs to exert a torque, ■ the closing by applying a within 60 which is sufficient to internal shear in a relatively limited and practically pre-lubricant intermediate layer cause and the ■ partial size range lying torque can unscrew friction between the guide ribs of the lid, which has to be overcome by the presence and the threads of the container, a lubricating intermediate layer between the sealant used to produce the sealant and the container, which comes from the 65 one a polyvinyl chloride resin. This resin can on the one hand be capable of modifying the size of the frictional resistance chloride or polyvinyl acetate that develops between, however, also with another substance, such as polyvinyl lid and container. To keep the state under control, but on the other hand, polyvinyl chloride resin in combination with a resin allows the formation of a frictional resistance of similar copolymers of vinyl chloride and of sufficient size, - in order to provide an effective seal- 70 vinylidene chloride forms an effective basic

■ material as described below. That Resin forms a paste with the plasticizer and becomes the same in the form of finely divided individual particles added, which distribute evenly as a suspension in the plasticizer. One can use any plasticizer provided it is non-volatile. A polyester epoxy and acetyl tributyl citrate have been found to be suitable plasticizers. A filler can be added in the form of finely divided individual particles that are evenly distributed in the mixture. A Fillers, such as barium sulfate, give the mixture an advantageous flowability. The resin should be in that plasticizer used in each case practically insoluble at room temperature, at higher temperatures, in which the plasticization takes place, but be soluble.

For every 100 parts by weight of resin, 50 to 250 parts by weight of plasticizer are preferably used. That The filler is preferably added in amounts of 0 to 250 parts by weight. To the mixture of The lubricant is the resin and plasticizer, which can be composed in a manner known per se added in an amount that depends both on the lubricant used and on the amount of resin, filler or plasticizer. Excessive amounts of lubricant can adversely affect the modulus, hardness and tensile strength of the sealant. Consequently the upper limit of the lubricant additive to the mass depends on its adverse effect on the physical condition of the finished sealant.

After the complete mixing of the resin and plasticizer mixture with the addition of the With a lubricant, the paste-like mass can easily be applied to the inside of a hollow cover body for production Apply a sealing ring or a sealing liner. The special kind of like a such a paste-like mixture is applied to the lid is known per se. The mixture has sufficient adhesiveness to adhere to the enameled inner surface of the lid and during the subsequent plasticization, through which the mixture is transformed into a permanent rubber-like gel is convicted to remain in his position. The plasticization of the mixture of resin and plasticizer is finished when the plastisol reaches a temperature of about 177 ° C, and on the surface of the sealing ring or the liner located on the lid is then a Lubricant coating that remains on the finished sealing ring and cover when it cools down. Since the lubricant coating or film is viscous, it remains on the surface of the sealant received, and even if the lid finally closes after a long period of storage of a container is used, the lubricity is not noticeably decreased.

A sealant base was used in a number of tests using lubricants used, where screw lids of 77 mm diameter with four guide ribs with the different Provided plastisol sealing rings and on the same glass container with helical guide ribs were put on. In all cases the glass containers were filled with calcium chloride, in order to absorb any moisture contained therein, which adversely affect the respective experiment could, and the lid to be tested was known on the jar in question with the help of a sealing machine Kind of screwed on under vacuum. The containers with the lids were then used for certain Periods of time were allowed to stand, and the torques in cmkg required for losing weight were measured the lids of the containers were required.

Base mass for the sealant parts by weight

Polyvinyl chloride 55

Copolymer of about 94% vinyl chloride and 6% vinylidene chloride ... 45

Acetyl tributyl citrate 50

Polyester epoxy 10

Stabilizing soap or

! 2 calcium ricinolate 1

Barium sulfate 50

Titanium dioxide pigment 1

212

The lubricant preferred according to the invention contains liquid silicone resin or liquid silicone resin and a sealing wax such as paraffin. However, advantageous results are also obtained if only liquid Silicone resin is applied. These lubricants not only show the beneficial ability to reduce friction under control, but also meet many other requirements for materials Use in food containers. You are e.g. B. not thermosetting, non-toxic and non-drying.

If one works with liquid silicone resin, then one preferably uses amounts in the range of about 0.5 to 15 percent by weight of the mass. .. Amounts of paraffin of about ibis are preferred 10% of the total weight of the mass added. These proportions of lubricants deliver independently whether they are added separately or together, a well-balanced lubrication system for the Plastisol mass. The preferred liquid silicone resin has a viscosity of about 35OcSt; man however, liquid silicone resins of other viscosities can also be added to the polyvinyl chloride compound, as far as they are able to produce the desired lubricating effect. As a waxy lubricant component paraffin is preferably used; However, you can also use other waxy substances work. Examples of such ingredients are long-chain fatty acids, such as stearic acid and myristic acid, Diglycol stearate, beeswax, polyamide wax, candelilla wax, octadecenylamine, polyethylene glycol, Japan wax, long chain alcohols such as stearyl and cetyl alcohol, and mixed paraffins.

The following table gives the procedure to use for unscrewing the various lids from the containers of the masses according to the invention required torques. In all cases the same base material used; the numbers next to the letters indicate the parts by weight of liquid silicone resin for S and the weight for P share in paraffin.

Torques required for opening, cmkg

Opening time after
Close up, days S-2.5 P-4.4
S-2.5 5
28
65
90 84.3
92.3
94.6
100.5 65.8
73.8
88.8
90

Each of the above values represents an average of three ■ opening attempts. The different ones to investigated mixtures were prepared with the addition of the specified amounts of lubricants, and the mass obtained in this way was poured into a lid in the form of a sealing ring and plasticized, whereupon the container in question was closed with the respective lid.

From the above results it can be seen that the torques required for opening are all were below 115 cmkg. Without the addition of a lubricant or mixture of lubricants to the base material the torque required to unscrew the lid from the container is more than 115 cmkg. The results are therefore a considerable improvement since the ones required to open them Torques are reduced and still an effective seal between the lid and the container is achieved. The paraffin used in the experiments was a paraffin available in the trade. That liquid silicone resin had a viscosity of 350 cSt.

The exclusive use of paraffin is not recommended, as this wax is on the surface the sealant after screwing the lid onto the container at the contact surface solidifies into a solid body that requires too high a torque to shear off when the Wants to unscrew the lid from the jar. However, the addition of paraffin makes it easier to screw on the lid on the container. Therefore, the preferred mixture of lubricants contains some Amount of paraffin in combination with liquid silicone resin.

When investigating with various polyvinyl chloride resin compositions have been carried out according to the invention, it has been found to be useful is to increase the amount of lubricants when the ratio of plasticizer to resin and or or the ratio of plasticizer to filler is increased. It is therefore appropriate that with an approximately constant percentage of lubricant, based on the total amount of ίο polyvinyl chloride resin compound, is being worked. Generally you have to increase the amount of plasticizer and / or filler also the amount of lubricant enlarge accordingly.

Claims (4)

PATENT CLAIMS: 1. Sealing compound based on a polyvinyl chloride resin for the production of a sealing ring, characterized in that it contains such a large amount of liquid silicone resin that it is found on its surface as a lubricant after the production of a sealing ring. 2. Sealing compound according to claim 1, characterized in that it is in addition to liquid silicone resin also contains paraffin. 3. Sealing compound according to claim 1, characterized in that it is about 0.5 to 15 percent by weight contains liquid silicone resin. 4. Sealing compound according to claim 2, characterized in that it is about 0.5 to 15 percent by weight contains liquid silicone resin and about 1 to 10 percent by weight paraffin. es 9fl <) κπινκ q so