GB2303630A - Cushioning and heat-insulating packaging material made of foamed cellulose - Google Patents

Description

CUSHIONING AND HEAT-INSULATING PACKAGING MATERIAL MADE OF FOAMED CELLULOSE

2303630 This invention relates to a cushioning (buffer) and heatinsulating packaging material made of foamed cellulose.

In the packaging of goods, it is usual to use a cushioning (or buffer) material to prevent the goods from damage or deformation during their transportation. A buffer material should have elasticity or the property that it is capable of absorbing impacts.

Usually, foamed plastic substances are used as the buffer material. For example, they include the plastic substances obtained by foaming ordinary plastics such as polyethylene (PE), polypropylene (PP), ethylenevinyl acetic acid copolymer (EVA), polystyrene (PS), denaturalized EVA, soft PVC, phenoxy resin and butadiene resin, or the buffer materials obtained by using elastic materials themselves or by foaming elastic materials such as natural rubber, rubber of SBR system, thermal plasticity rubber of s-Lyrene-butadiene system, butadiene rubber(BR), isoprene rubber(IR), ethylene propylene multipolymer rubber(EMP), polychloroprene rubber(CR), butyl rubber(IIR), urethane rubber, silicone rubber, multification rubber, acryl rubber, chlorosulfonated styrene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, propylene oxide rubber, ethylenevinyl acetic acid rubber, thermal plastic rubber. Polyethylene foam or polystyrene foam which are cheap are particularly common packaging materials.

Even though these plastic substances or rubber substances have excellent properties as cushioning (buffer) materials, since they cause environmental pollution due to the fact that they do not decay naturally and toxic gas is produced when they are burned, the use of natural or synthetic rubber materials is prohibited in developed countries. Moreover, in the near future, use of these substances will probably be prohibited in the whole world.

Also, in order to solve these problems, pulp or cellulose substance is used as a buffer material by forming directly. However, these buffer materials have been limited in their use since their absorbability is low so that their role as the buffer materials cannot be carried out.

Some patents describing such buffer materials made from these cellulose substance are as follows:

US Patent No. 5,230,943 discloses free-flowing dunnage packing material which is made from molded pulp to form non-planar, dish-like shapes.

US Patent No. 4,937,131 discloses a flexible, cushioning dunnage product producible on a converter mechanism from a roll of sheet-like stock material, such as biodegradable paper.

US Patent No. 5, 312, 665 discloses a loose-f ill packing material comprising a plurality of individual packing elements. Each packing element comprises at least two paper rings which are connected to each other at their outer surfaces.

US Patent No. 5,308,677 discloses package stuffing comprisina a flat base having arcuate or geometrically shaped cross section from one face of which extended projections having reverse arc or shape to that of the base below each of which is a cutout or slot.

US Patent No. 5,173,352 discloses a resilient packing product which is made of a plurality of narrow, elongated strios of paper material; the paper material having a natural resilience; and each of the strips including a plurality of transverse 1C Lolds against the natural resilience to Lorm a longitudinally compressed scrip element. - US Patent No. 5,151,312 discloses lightweight, non-nestable packing peanuts formed of recycled newspaper of molded hollow ghin wrall shell form preferable of cup shaped configuration have flanges, apertures, and double wall dividers Jntegrally molded therin.

US Patent No. 5,213,867 discloses cetrahedial loose-fill packing made of paper.

US Patent No. 4,566,831 discloses a shock absorbent dunnage device of a sealed outer envelope containing filler of wooden particulate material having reduced moisture concent.

US Patent No. 4,109,040 discloses a cushioning dunnage product: produceable from a mechanism which -is of relatively compact nezure utilizing a roll of sheet-like stock material, such as paper.

However, the buffer material having buf.Lering a nd heat- insulating effects which is manufactured by foaming cellulose substances such as pulp or waste paper has not been developed until- now.

BAD ORIGINAL After carrying out long research, the inventors completze this invention by discovering the facts that if cellulose substance is wet-foamed with normal foaming agent and normal water-soluble adhesives and then dried, the volume 2rom 20% to 500%, th of cellulose substance is foamed 4 I.e foamed cellulose substance as like this is very useful as er material because its absorbability to an impact a buff is very great, and heat-insulating effect is very excellent because lots of pores are formed inside.

4. rl g 4 ng Also, tlne buffer and heat-insulat material us, the foamed cellulose substance manufactured as like this decays faster than normal cellulose substance in the nature since lots of poies are formed inside. Thus, this does not. occur pollution problem, can prevent pollution by recycling the waste resources, is suiz:able to Green Round and therefore can be used widely as a subsidiary material for packing export products as so-called green pioducts.

Therefore, an object of the invention is to provide the buffer and heatinsulating matezial using cellulose which is obtained by foaming cellulose with adhesives and foaming agents and then substance substance drying it. Another object of the -invent-ion is to provide the manufacturing method of the buffer and heat-insulating material using cellulose substance which is obtained by foaming cellulose with adhesives and foaming agents and then drying it.

The cellulose substances which can be used in the r BAD ORIGMAL 1 invention include normal cellulose substances such as pulp, waste paper, etc..

As adhesives which can be used in the invention, starch, sodium carboxymethyl cellulose, ethyl cellulose, methyl cellulose, sodium alginate, casein, gelatin, polyvinyl IPV.Ac) and the or-her aicohol(PVA), polyvinyl acetacek normal war-er-soluble adhesives can be used singly c-by mixing more rhan 2 kinds thereof.

Even though the amount used of adhesives can be different f adhesives and adhesive force, depending on the kinds cl. normally 0.1 - 20 wt % can be used. In this invention, normal foaming agents are used by foaming. As the foaming agents, organic foaming agents such as azodicarbonamide(ADCA), azobisformamide(ABFA), azcbisi-sobu--V--onit--il-e(AIBN), pentamethylene hyciraz-J'de(TS:), N,N'-denitroso tetramine(DPT) P-coluenesulfonyl P,P'-oxyb-is(benzenesulfonyl hydrazide) (OSSF) and inorganic foaming agents such as ammonium carbonate, sodium hydrogen carbonate can be used singly or by mixing more than 2 kinds thereof. The amount used of these foaming agent-s can use from 0.5 to 20 wt% to the total weight.

The pulp may be used directly into che manufacturing process. The waste paper may be used by beating and dehydrating afrer removing impurities. The mcisrure content: after dehydrating of the cellulose substance is about 30%, and such cellulose substance is used 50 - 80 wt% tor-ally.

The amount of moisture in the manufacturing process is 10 BAD ORIGINAL 30 wt% The description of each follows:

1 Pulping process (the case of using waste papers) T Ihe process that each kind of waste paper is torn into pieces with water in order to obtain pulp. In the case oil us_-ing pulp, it is directly used and this process is omitted.

2. Screening process (the case of using waste pacer) The process that each kind of impurities (each -kind of plastic 'substance such - as vinyl, impurities of iron content, earth or sand) is selectively removed from the pulp manufactured in the first process. in the case of using pulp, this process is omitted.

3. Defiring process The process that the pulp obtained from second process is manufactured to the finer fibroid material-. Depending on the wasze paper used, this process can be omitted.

4. Dehydrating process T 1he pulp obtained from the second process (the case of omitting the third process) or from the third process is dehydrated to be the content of water of about 10-30 wt% by using a normal dehydrator. 5. Mixing process T Lhe pulp obtained from the fourth process or pure pulp is mIxed with water-soluble adhesives and foaming agent, and if needed, water.

6. Preheating process The mixture obtained from the fifth process is preheated step of the processes is as PAD ORIGINAL 1 to abo u t 30-9oc. In the case of using ammonium carbonate as a foaming agent, it is heated to a low temperature whereas in the case of using foaming agent which has a high decomposition temperature, it is heated to a high temperature.

7. Forming and second foaming process The preheated mixture obtained from the sixth process formed and foamed by putting it: in the molld desired form and then heating at about 70-1501. In case of using ammonium carbonate which has a decomposition temperature as a foaming agent, it can foamed in a low temperature.

8. Drying process A foamed product is obtained by drying the formed and foamed material oncained frcm che se-z.,enth process.

The present invention will now be illustrated more fully by the following Examples.

havina i S a the low be Examnle 1:

ikg of waste paper is put in 600mi of water and beaten After each kind of impurities is removed, the beaten waste paper is dehydrated until the water content is about 30 we%. About 20g of gelatin is dissolved in water at 601C to be che concentration of 30wt%, and separately 2g of sodium carboxymeth-yl cellulose(sodium CMC) is dissolved in water to be the concentration of 3wC%. After mixing tne gelatin solution with the sodium CMC solution, about!Og of azobisisobutyionitrile(AIBIJ) as the foaming agent is added thereto, and the resulting mixture solution is mixed with the beaten waste paper prepared h., '.1 1 above and the whole mixture obtained thereby is heated to about 851C. TM! heated mixture is poured into a forming mold and then is formed and foamed by heating at about 1200C. A foamed product to 150 vol% is obtained and dried.

Example 2:

Water is added to lkg cf pulp so that. water content is controlled to be about 25%. Sepatately, 30g of sodium alginate is dissolved in water to be the concentration of 2owt%, and resulting solution is mixed with pulp. 3g of ammonium carbonate is dissolved in cold water to be the concentration of lowt% and resultina solution is mixed homogeneously with the pulp mixture. This mixture is heated at about 401C, put in a mold, heated at about 801C and formed and foamed and then dried. A foamed product to 200 vo'L% is obtained.

Examul e 3.

E water and beaten, lkg of waste paper is put in 600ml oL and each kind of impurities is removed. The beaten waste pacer is dehydrated to be the water content of about 30%. Separately, 30g of starch is put in looml of warmed water and by boiling and then cooling, starch size is obtained, and the obtained starch size is mixed with log of azobisformamide.(ABFA) as a foaming agenz. This mixture is mixed with pulp. After heating the mixture at- about 90. C, it: is puc in a mold, and formed and foamed by hearing at about 1150 - C. A foamed producz to about 200 vol% is BAD ORIGINAL C_.! 9 obtained after drying.

Other foaming agents and adhesives can be used for manufacturing foamed products of cellulose by using the methods of Example 1 to Example 3.

A foamed product which is hard can be manufactured by reducing the amount of adhesive or the degree of foaming, whereas a foamed product which is soft can be manufactured by increasing the amount of foaming agent or by reducing the amount of adhesive.

The foamed material of cellulose substance manufactured in accordance with the invention has good elasticity and heatinsulating properties and is light in weight so that it can be used as a cushioning (buffer) material and heat-insulating material of all sorts.

The foasmed products according to this invention are made c- cellulcse substance which is unharmful to huma:s and is biodegradable, and also the adhesives are not harmf-,_1'L to human body and the used foaming agents are c:han.--:ed to unharmful cas so that they are not harmful to human body t all..

BAD ORGINAL 1 -

Claims (6)

1. A process for preparing a cushioning and heat-insulating packaging material based on cellulose, which process comprises pulping and dehydrating a cellulose substance, adding a watersoluble adhesive and a foaming agent thereto, wet-foaming the resultant mixture to the desired form, and drying it.

2. A process according to claim 1, wherein the said resultant mixture is foamed to a volume of from 20 to 50006 of the original volume of the mixture.

3. A process according to claim 1 or claim 2, wherein the water-soluble adhesive is at least one of starch, sodium carboxymethyl cellulose, ethyl cellulose, methyl cellulose, alginic acidic sodium, casein, gelatin, polyvinyl alcohol (PVA) and polyvinyl acetate(PVAc).

4. A process according to any one of the preceding claims, wherein the foaming agent is at least one of azodicarbonamide (ADCA), azobisformamide(ABFA), azobisisobutyronitrile(AIBN), N,N'dinitrosopentamethylene tetramine(DPT), p-toluenesulfonylhydrazide(TSH),p, p'-oxybis(benzenesulfonyl)-hydrazide(OBSH), ammonium carbonate and sodium hydrogen carbonate.

5. A process according to claim 1, substantially as described in any one of the foregoing Examples.

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6. A cellulose-based cushioning and heat-insulating packaging material whenever prepared by a process as claimed in any one of the preceding claims.