WO1987000820A1

WO1987000820A1 - Process for the manufacture of a liquid absorbing pad

Info

Publication number: WO1987000820A1
Application number: PCT/SE1986/000357
Authority: WO
Inventors: Jan Olof Valentin Berglund
Original assignee: Brabis Investment Ltd.
Priority date: 1985-08-09
Filing date: 1986-08-07
Publication date: 1987-02-12
Also published as: AU6224386A; SE450764B; EP0232360A1; SE8503759D0; SE8503759L

Abstract

Process for the manufacture of a liquid absorbing pad comprising a liquid absorbate particulate material and spacer means between two of the sides of the pad, whereby on a first sheeting (1) intended to form one side of the pad given dosages (11) of a polymer mixture which foams while curing, when said polymer mixture has foamed, cured, and attached to said first sheeting (1) this is brought together with a second sheeting (5) intended to form the other side of the pad while simultaneously sealing the sheetings (1, 5) together along two sides, whereupon a liquid absorbing, particulate material (12) is introduced between the sheetings (1, 5), whereupon the pad is sealed to the formation of a closed unit, whereby at least one of said sheetings (1, 5) consists of a liquid permeable material and whereby the polymer mixture which foams while curing forms spacer means (13) between said sheetings (1, 5).

Description

PROCESS FOR THE MANUFACTURE OF A LIQUID ABSORBING PAD.

DESCRIPTION Tec πi ca L Field

The present invention relates to a process for the manufac¬ ture of a liquid absorbing pad comprising a liquid absorbing material in particualte form and spacer means.

The object of the present invention is to obtain an improved liquid absorbing pad to be used at the transport of food pro- 10 ducts, where the food product as such give off water, or where the ^'food product is kept cold by means of ice, which melts during transport, and to obta n an improved, faster technique to manufacture such a pad.

5 Background of the invention.

It is previously known (N0-A1 -830621 , US-A-4,321 ,997) to transport food products on a liquid absorbing pad or pi llow, which pad comprises a liquid absorbing material, and spacer means to prevent compression, and thereby a reduced absorption

20* capacity of the absorbing material.

It has, however, turned out that the spacer means arranged are not distributed in the correct number, or are not kept in the place intended in such known pads, why problems have 5 occurred concerning the intended, specified liquid absorption. Thus it is important that the spacer means are kept in place, and are present in an amount large enough, particularly at air freight transports of ice chilled fish, where large amounts of water are produced during a freight period, and

30 where substantially no water is allowed to leave the transport package, as other si ultaneously freighted goods then can be easi ly damaged. It is also a hygienic demand that water, often y blood mixed from the slaughtered fish, shall not penetrate out off the package, and that it is kept isolated from the

35 fish to give maximal shelf life. Today, it is particularly common to freight cultivated, slaughtered fresh fish from Scandinavia to North America, where the freight time, as easi¬ ly understood, become long and chi lling ice melts almost com- pletely during this time period, even if the freight takes place in heat insulated boxes.

Description of the present invention. It has now surprisingly been shown possible to eliminate these problems and to manufacture an improved liquid absorbing pad in accordance with the present process, which is character zed in that on a first sheeting intended to form one side of the pad, given amounts of a polymer mixture, which cures whi le foaming, are subsequently applied, when said polymer mixture has foamed, cured and been fixed to said first sheeting, this sheeting is brought together with a second sheeting intended to form the second side of the pad, whi le simultaneously fix¬ ing the sheetings together, whereupon a liquid absorbing, par- ticulate material is introduced between the sheetings, where¬ upon the pad is finally cLosed to the formation of a closed unit, at least one of the sheetings being made of a liquid permeable material, and the polymer mixture, which is cured while foaming, forming spacer means between said sheetings. The spacer means are preferably fixed to the second sheeting to give maximal stabi lity and keeping in place of the particu-^' late, liquid absorbing material contained therein.

Further, characteristics are evident from the accompan ing claims.

The invention wi ll be described more in detai l in the follow¬ ing with reference to the attached drawing, the single figure of which schematically shows a device for carrying out the process .

1 denotes a first continous sheeting, preferably made of a cellulosic material, such as a non-woven fiber foi l being un- winded from a first reel 2. The sheeting 1 passes below a__^_____.- dosaging unit 3, which distributes given doses/dabs 11 of a po lyo l-i socyanate mixture subsequent to each other at equal distances. The polymer material is prefoamed at the distribu¬ tion and has the consistency of hard whipped cream. The poly- mer mixture has at the distribution a volume which is about 1/50th of the final volume. Distribution can take place in one, two or more rows, preferably two. The polymer material thus dosaged is allowed to foam to the intended predetermined height during s multaneous curing during the transport of the sheeting 1 in the direction indicated by the arrow. The poly¬ mer doses applied attach to the sheeting 1.

When the sheeting 1 passes point 4 a glueing agent is applied, such as a melting glue, which is applied onto the outer edges of the sheeting 1. Then the sheeting 1 is^' brought together with a second sheeting 5 coming from a reel 6. In the combin¬ ing point the sheetings 1 and 5 are fixed together along their two long sides by applying heat. Simultaneously with the bringing together of the sheetings the second sheeting 5 at¬ taches to the foamed polymer material so that in practise the sheetings 1 and 5 are linked together also via the spacer means 13, the now foamed and cured polymer doses 11. As the sheetings 1 and 5 are brought together a liquid absorbing, particulate material 12 is blown in between the sheetings 1 and 5. The material 12 is distributed forward from a si lo (not shown) via a dosage screw 9 and s preferably blown into the pad housing, i .e. between the sheetings 1,5. The material 12 which can consist of a hydrophi lic polycarbamide. a hydrophi l- ic cellulose fiber, a starch derivative, (starch acrylonitri le copolymer) or a water absorbing polyurethane, suitably ha ing a density of 1 g/dm , should have a water absorption capacity of 50-150 g H O per gram of polymer. If a polymer of the poly¬ urethane type is used the polymer should be rolled in order to open up its cell structure, which often becomes closed dur¬ ing the foaming-curing operation. One can also form the absor¬ bent Jj situ by introducing a po lyo l-i socyanate mixture, which at the addition of water, as by the melting of ice is brought to react to the formation of a polyurethane having liquid ab- sorbing properties.

The polymer balls 13 are used at the sealing as mentioned above as they then are sti ll sticky. When the material has been introduced between the sheetings 1 and 5, the sheetings 1 and 5 are sealed at a sealing station 10 and is then cut to a suitable length.. In connection with the sealing the sheetings 1 and 5 are sealed, whereby, when the material is brought in between the sheetings 1 and 5, three sides of the intended pad are, in reality, sealed. The cutting takes place in the centre of a sealing l ne.

The sheeting 5 need not be totally permeable to water, such as a cellulosic sheeting wi ll be, but can consist of a fi lm coated, perforated sheeting which admits the passage of water. Thus a polyethylene coated, perforated paper- sheet i πg can be used .

It is important that the pad is fi lled with a highly porous ^" foam, which simultaneously provides a good insulation in the beginning of the transport and then, subsequently keeps the cold water therein.

In order to better bind the water or other liquid to the ab¬ sorption material this can be mixed with a gelling agent, thickening agent, which swells whi le binding water, such as a cellulose derivative, a starch derivative, or different polymer particles having hydrophi lic properties.

In accordance with a further aspect of the present invention a liquid absorbing pad of above can be placed and/or manufac¬ tured onto a larger backing, such as a polyethylene foi l, which has a larger width and length than the absorbing pad, whereby heat insulating sheets of e.g. foamed polyurethane or polystyrene are placed onto the extending parts of the foi l. The heat insulating sheets have thereby such measures and dimensions that they fit into an outer package, such as a hard board box. Thus one places one sheet on each side of the long sides of the absorbing pad and one sheet on each side of the short sides of the absorbing pad. Thereby at each cor¬ ner a free foi l surface is created which is preferably pre- folded so as to easily fold when placed into a box. A heat insulating sheet can of course be placed underneath the ab¬ sorbing pad, either above or underneath the foil. By this em¬ bodiment of the invention a separate manufacture and distribu¬ tion of the heat insulating sheets or combined sheets can be eliminated, and the application into a box is made more ra- t i ona I .

Claims

CLAIMS,

1. Process for the manufacture of a liquid absorbing pad com¬ prising a liquid absorbing, particulate material and spacer means, characterized in that on a first sheeting (1) intended to form one side of the pad, given dosages (11) of a polymer mixture which cures whi le foaming, are subsequently applied, when said polymer mixture has foamed, cured and been fixed to said first sheeting (1), this sheeting is brought together with a second sheeting (5) intended to form the second side of the pad, whi le simultaneously fixing the sheetings (1,5) together along two of its sides, whereupon a liquid absorbing, particulate material (12) is introduced between the sheetings (1,5), whereupon the pad is finally closed to the formation of a closed unit, at least one of the sheetings (1,5) being made of a liquid permeable material, and the polymer mixture, which is cured whi le foaming is forming spacer means (13) be¬ tween said sheetings (1,5) .

2. Process according to claim 1, characterized in that the polymer mixture (11) is attached to both the sheetings, (1,5) and thereby binds stabi lizes the pad with its liquid absorbing contents .

3. Process according to claim 1, characterized in that said polymer mixture consists of a polyisocyanate, which foams whi le curing.

4. Process according to claim 1, characterized in that liquid absorbing material is a po lyca rbami de .

5. Process according to claim 1, characterized in that the liquid absorbing material is a modified starch.

6. Process according to claim 1, characterized in that the liquid absorbing material is a hydrophi lic cellulose product,

7. Process according to claim 1, characterized in that the liquid absorbing material is a foamed polyurethane having an open cell structure, possibly obtained by rolling the foamed polyurethane.

8. Process according to claim 1, characterized in that the polyurethane is formed _i_n situ at liquid absorption.

9. Process according to claims 3-7, characterized in that the liquid absorbing material can absorb water in an 'amount of at least 50 g H-,0 p e r g of absorbing material, preferably 100 g H-,0 per g of absorbing material.

10. Process according to claims 1-9, characterized in that the liquid absorbing material is blown into the pad.

11. Process according to claims 1-10, characterized in that^' the liquid absorbing pad is manufactured onto a backing having larger width and length than the pad, whereby on each side of the pad heat insulating sheets are placed to form a final heat nsulating/liquid absorbing unit. . •