GB2154198A

GB2154198A - Latex collecting container

Info

Publication number: GB2154198A
Application number: GB08507262A
Authority: GB
Inventors: Emil Davidson
Original assignee: STJ Sdn Bhd
Current assignee: STJ Sdn Bhd
Priority date: 1982-01-25
Filing date: 1985-03-20
Publication date: 1985-09-04
Also published as: GB8507262D0

Abstract

A latex collecting container blow moulded from a thermoplastic resin incorporating high molecular weight fatty acids to give a lubricated inner surface. The container may have ribs or segmented ribs 8 on its outer surface to engage a wire rack or support, the ribs being either notched by engagement with the wire or preformed with a plurality of notches. The fatty acids, which may be oleic, palmitic or stearic acids, are either added to the thermoplastic resin before forming the container or applied to the inner surface of the container after moulding. <IMAGE>

Description

SPECIFICATION Latex collecting containers The present invention relates to latex collecting containers.

The latex collecting containers now in general use are hand made of ceramic materiais which have a smooth glazed internal surface permitting easy removal of the liquid latex and specifically the coagulated bottom layer of the latex. They also have the necessary weight to prevent them from being blown by wind or carried by flood waters out of the wire racks which support them on the trees.

However such ceramic containers are relatively expensive to produce and are often damaged in use causing the inner surface to become roughened. The roughened surfacer makes removal of the latex difficult and causes abrasions and cuts to the hands of the workers removing the latex. It has been proposed to use plastic latex collecting containers, but the latex tends to stick to the container surface.

In our copending Application No. 8202057, from which the present application has been divided out, there is claimed a latex collecting container in the form of a generally round-bottomed cup made of plastics material, having protrusions on its outer surface capable of engaging a support framework to oppose axial movement of the container out of the framework.

According to the present invention, there is provided'a latex-collecting container having a smooth concave inner surface, wherein the container is formed from a resilient thermoplastics material bearing at least at the inner surface a minor proportion of high molecular weight fatty acids.

The high molecular weight fatty acids may be, for example, oleic, stearic or plamitic acids. preferably, the fatty acids are added to the thermoplastic resin before forming the container.

Latex collecting containers according to the present invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a latex collecting container; Figure 2 is a section of part of Figure 1 on an enlarged scale taken on line Il-Il; Figure 3 is a section of part of Figure 2 taken on line Ill-Ill; Figure 4 is a section corresponding to that in Figure 3 but of different construction of container; and Figure 5 is a perspective view of a further construction of the container.

The latex collecting container 1 in Figure 1 is blow moulded from a thermoplastic resin such as high density or low density polyethylene or polypropylene. Incorporated into the resin before moulding are small compatible percentages of high molecular weight fatty acids such as Oleic acid, Palmitic acid or Stearic acid. Alternatively these acids can be applied to the inner surface 2 of the container after moulding.

The inner surface 2 of the container is completely smooth and due to migration of the added fatty acids to the surface of the contaner the inner surface is lubricated by the fatty acids. This resists the tendency of the coagulated latex to stick to the container, making removal of the latex easier. The migration of the fatty acids to the surface continues for a long period of time, giving several years of useful life.

Small amounts of high molecular weight fatty acids are always present in the latex so no contamination or adverse reaction is caused by the lubricating fatty acids.

The mouth of the container 1 has a lip 3 and on the outside are twelve ribs 4 spaced apart round the container at intervals of 30 . As seen more clearly in Figure 2, each rib is of essentially triangular section. The ribs extend from the base of the container to its lip 3 and lie in planes through the central axis of the container.

In use, when the latex collecting container 1 is pressed into a conventional wire rack or support secured to a rubber tree, the wires exert a substantial pressure on the narrow edges of the triangular ribs. This pressure causes indentations in the plastics material of the ribs and after a period of some hours the indentations become permanent due to "cold flow". Cold flow is a molecular re-orientation which takes place in thermoplastic resins under these conditions. The permanent indentations in the ribs 4, as shown in Figure 3, engage the wires 5 and hold the container firmly in the rack, resisting blow out by wind or removal by flood waters.

The more downward force exerted when placing the cups in the racks the greater the undercut formed in the ribs 4 and the more secure are the cups. Similarly the greater the weight of latex the more secure are the cups.

In a second embodiment of the invention the ribs 4 are essentially as in Figures 1 to 3 but notches 6 are preformed in the ribs, see Figure 4.

These notches 6 provide a plurality of levels at which the wire of a rack or support can engage the container when it is pressed into position. Further ribs lying either in planes through the central axis of the container or perpendicular to it may be provided in either embodiment to mechanically reinforce the container and increase its strength and rigidity.

In a further embodiment of the invention shown in Figure 5 protrusions from the outer surface of the container are provided in the form of interrupted or segmented rings 7. Each ring lies in a plane perpendicular to the central axis of the container and the rings are spaced apart to allow a rack or support to pass over and lie between the rings. Each segment 8 of the rings 7 is radiused on its outer surface to allow the rack to pass smoothly over the lowermost rings when the container is pressed into position and to then hold the container securely. By having a plurality of interrupted rings 7 there is provided a plurality of levels at which the rack can engage the container as in the previously described embodiments, this allowing for variations in the size of the rack.

Whilst the ribs 4 and rings 7 have been described as separate embodiments they may be combined to give a suitable pattern of protusions on the container.

In all the embodiments the container is preferably blow moulded as previously described. A small raised portion may be provided at the bottom of the inside of the container and the numbers of ribs or rings may be varied from those described if necessary.

Claims

1. A latex-collecting container having a smooth concave inner surface, wherein the container is formed from a resilient thermoplastics material bearing at least at the inner surface a minor proportion of high molecular weight fatty acids.

2. A container according to claim 1, wherein the fatty acids are added to the thermoplastic resin before forming the container.

3. A container according to claim 1 or 2, wherein the fatty acids are Oleic, Palmitic, or Stearic acids.