DK146416B - MATERIALS FOR USE IN COOLING ELEMENTS - Google Patents

Description

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(19) DENMARK

f da) PUBLICATION MANUAL OR 146416 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Patent Application No. 0655/71 (51) Int.CI.3: C09K 5/00 (22) Filing Date: 12 Feb 1971 (41) Aim. available: 14 Aug 1971 (44) Submitted: 03 Oct 1983 (86) International Application No: - (30) Priority: 13feb1970NL7002050 (71) Applicant: N.V. * VAMUS; de Zllk, NL.

(72) Inventor: Louiens Barend of * Munster; NL

(74) Plenipotentiary: Engineering Company Budde, Schou & Co (54) Material for use in cooling elements

The invention relates to a material for use in cooling elements. Cooling elements, e.g. plastic bags filled with a coolant, e.g. water is known. These elements are first cooled, usually at least until the coolant is completely frozen. Then the cooling elements, together with the objects to be kept at a certain low temperature, are placed in a heat insulating package. The inflowing heat is mainly absorbed by the cooling element in the form of the cooling heat of the refrigerant.

OQ A disadvantage associated with this cooling method is that {q if the coolant casing is torn, the molten coolant will run out and come into direct contact with the cooled articles. Therefore, it has been proposed to prevent outflow by the addition of a gelatin ring coolant to the coolant. However, the proposed gelling agents have proved unsatisfactory in practical use, especially when the coolant contains a substantial amount of electrolyte. Although the refrigerant becomes yellowish, which prevents outflow in the event of minor damage to the cooling element, the refrigerant flows out when the casing is severely damaged.

It has now been found that a material for use in cooling elements and which does not flow out, even by serious damage to the container.

Accordingly, the invention relates to a material for use in cooling elements containing a mixture of a gelling agent, water and optionally an electrolyte and / or a preservative, and this material is characterized in that the gelling agent is a galacto-mannan and that the mixture further contains carboxymethyl cellulose. as crystal growth inhibitory additive in an amount of 0.5-5% by weight of the total mixture.

This material is a rigid gel and can best be described as a more or less rubbery, elastic substance. The gel must, of course, be able to withstand low temperatures and be resilient enough to allow an expansion of approx. 10 percent (corresponding to water expansion by freezing).

It is preferably used as galacto-mannan methylated guar-gum-mi, which is also very effective when the water contains a large amount of electrolyte.

According to the invention, it is essential that a crystal growth inhibitor be present in the material. It has been found that if this agent is not added, freezing will give rise to a highly defective gel structure, so that the water or electrolyte solution after thawing will flow out of the container if it is torn. This is especially true when the freezing and thawing operations are repeated, ie. when the cooling element is used several times. Preferably, as crystal growth inhibitory additive, carboxymethyl cellulose is used which is easy to obtain and relatively economical.

In order to ensure repeated use of the cooling elements, if necessary, it is advantageous to add a preservative to the material, since the gelling agents are usually subject to biodegradation. As particularly suitable preservatives, e.g. name the various quaternary ammonium bases.

Preferably, the cooling material contains one or more electrolytes. The amount of electrolyte added is preferably so large that the material produced is more or less similar to the material at the eutectic freezing point of the electrolyte / water system involved.

As a rule, the gelling agent is used in a ratio of 1-20 percent, based on the total weight of the material. Methylated guar gum is preferably used in amounts of 3-10 percent by weight. In a material with a high electrolyte content, e.g. 15-40% by weight, it is most advantageous to use 5.5-6.5% by weight of methylated guar gum. If no electrolytes are present, an amount of methylated guar gum of 3.5-4.5% by weight is preferred.

Carboxymethyl cellulose is preferably used in amounts of between 1 and 3% by weight. In the presence of a considerable electrolyte content, 1.5-2.5% by weight of carboxymethyl cellulose is preferably used. If no electrolyte is present, preferably between 1 and 1.5% by weight of carboxymethyl cellulose should be used.

The material is designed as a dry mixture for use in the preparation of the cooling material. The mixture contains a gelling agent and a crystal growth inhibitor, usually in a ratio of 40: 1 to 1: 5. The mixture may also contain one or more electrolytes as well as preservatives. The preferred blend contains methylated guar gum as a gelling agent and carboxymethyl cellulose as a crystal growth inhibitor, preferably in a ratio of 1: 1 to 10: 1.

The aqueous material according to the invention can advantageously be used in a coating consisting of plastic material, e.g. polyethylene, or in a coating of coated or uncoated paper.

The invention is illustrated by the following example:

Example.

A mixture is prepared containing 22.4 wt% NaCl, 2.0 wt% carboxymethyl cellulose and 6.0 wt% methylated guar gum, the remainder being water.

The gel thus produced behaves like a rubbery, elastic substance. It is frozen and thawed repeatedly, and not only once has the thawed gel released a noticeable amount of liquid.