WO2013141687A1

WO2013141687A1 - Pulp composition, pulp article(s) and preparation process thereof

Info

Publication number: WO2013141687A1
Application number: PCT/MY2012/000061
Authority: WO
Inventors: Ramaness PARASURAMAN
Original assignee: Parasuraman Ramaness
Priority date: 2012-03-22
Filing date: 2012-03-22
Publication date: 2013-09-26
Also published as: GB201418733D0; GB2518063A; GB2518063A8

Abstract

The invention provides a biodegradable and/or compostable pulp composition, moulded pulp article(s) and preparation process thereof. The pulp composition is prepared from non-wood fibres with diameters from 2.5 to 10 μιτι. The pulp composition may further comprise at least one exogenous protease, e.g. papain. The pulp composition may be moulded into at least one moulded pulp article. The moulded pulp article(s) according to the invention may be biodegraded and/or composted within 45 to 180 days. The biodegradable and/or compostable pulp composition may also be composted. The compost obtained may be used as fertilisers. The biodegradable and/or compostable pulp composition and/or the moulded pulp article(s) may also be used as animal feed.

Description

PULP COMPOSITION, PULP ARTICLE(S) AND PREPARATION PROCESS THEREOF

Field of the invention

The present invention relates to pulp compositions suitable for moulding and moulded pulp article(s) and their preparation. In particular, the invention relates to biodegradable and/or compostable pulp compositions, moulded pulp and article(s) and their preparation thereof.

Background of the invention

Disposable products made from polymer-based plastic, such as polystyrene and polyethylene, are generally not considered to be environmentally friendly. Such disposable plastic products may be used for food packaging and containers. It is estimated that a single plastic product may take up to 1000 years to decay completely. The persistence of plastic can result in ecosystem damage. In order to reduce the plastic presence, plastic may be incinerated together with the bulk garbage prior to dumping in landfills. However, the incineration of plastic has its fair share of disadvantages, the biggest being toxic fumes released into the environment, thus resulting in air pollution.

In addition, there are increasing concerns on the effects of polystyrene food containers. Hot food or beverages may cause styrene chemicals to leach into food or drink. This is a health concern as very high doses of styrene act as a neurotoxin, may be carcinogenic and affect fertility.

Biodegradable disposable products are available. The European Standard EN 13432 "Requirements for packaging recoverable through composting and biodegradation - Test scheme and evaluation criteria for the final acceptance of packaging", defines a set of characteristics that a material must have, in order to be defined as "compostable". Not all disposable products presently available meet this standard. It is desirable to develop environmentally friendly disposable products capable of rapid biodegradation and/or composting.

Summary of the invention

The present invention relates to pulp compositions suitable for moulding and moulded pulp article(s) and their preparation. In particular, the pulp compositions and/or moulded pulp article(s) are biodegradable and/or compostable.

According to a first aspect, the present invention provides a process for preparing a biodegradable and/or compostable pulp composition comprising the steps of:

(i) providing non-wood fibres;

(ii) selecting fibres having a diameter from 2.5 to 10 μΐη;

(iii) preparing a pulp composition from the fibres from step (ii) The invention also relates to a biodegradable and/or compostable pulp composition prepared by the process.

The biodegradable and/or compostable pulp composition according to the invention is suitable for moulding at least one moulded pulp article. Accordingly, the invention further relates to a biodegradable and/or compostable moulded pulp article moulded from the pulp composition.

Brief description of the figures

Figure 1 shows examples of moulded pulp articles according to the invention; (A) three-section plate; (B) plain plate; (C) five-section tray; (D) bowl; (E) cups; (F) cutlery; (G) clam-shell lunch box; (H) meat tray; (I) egg tray (or egg carton) and (J) wine tray. Definitions

"Agricultural waste" refers to any matter from premises used for agriculture or horticulture, which is discarded, to be discarded or is required to discarded. It is waste specifically generated by agricultural activities. "Exogenous" as used herein, describes a compound from a source outside or external to a composition. In particular, the exogenous compound has been added or introduced to the composition. For example, in the context of the present invention, a protease was added into a pulp composition. The protease is exogenous to the pulp composition even though both may be from the same plant. For example, the pulp composition may be from the stem while the protease may be from the fruit of the same plant. In a further example, the protease is also exogenous if obtained or purified from a separate batch of stems to the pulp composition.

"Bagasse" refers to the residue left behind after a plant or part thereof has been subjected to squeezing, crushing, grinding pounding or other mechanical or chemical processing. For example, bagasse refers to the residue left behind after a plant or part thereof has been processed to extract a product (for example: juice). Bagasse typically comprises fibre, pith (the spongy tissue of a plant), non-soluble solids and water. Bagasse may be obtained from any plant or part thereof including but not limited to sugarcane, grasses, cereal plants, bamboo, palm, coconut, corn or yam. Sugarcane bagasse is the fibrous product remaining after sugarcane stalks have been crushed to extract juice and is a byproduct of the sugar industry.

"Biodegradable" describes any material capable of being substantially degraded, decomposed or broken down by natural or biological processes.

"Composting" or "compostable" refers to the biodegradation or decomposition of organic matter and is carried out by various microorganisms, including bacteria, fungi and the like. The product of composting is compost which comprises a mixture of decaying organic matter. Compost may be used as a fertiliser.

"Impregnate" or "impregnated" as used herein means to cause a compound to be dispersed completely. Impregnated throughout means that the compound may be found in every part of an article, that is both within and on the surface of the article. For example, the impregnated compound may be embedded throughout the structure of the article.

A "moulded pulp" (also known as "moulded fibre") article refers to an article moulded from pulp. Moulded pulp article(s) may be moulded into almost any shape and size from pulp. Examples of moulded pulp articles include but are not limited to cutlery, containers, for example food containers (bowls, plates, cups, clam-shell containers), trays, egg cartons and other packaging material.

"Non-wood" fibres refer to fibres from any non-wood plant or non-wood part of a plant. For example, non-wood fibres may be from the stem of non-wood plants, which are plants which do not have woody stems. Woody plants may also have non-wood plant parts and non-wood fibres encompass fibres from these non-wood plant parts.

"Non-wood" plant refers to a plant which does not have woody stems.

"Non-wood" plant part refers to a plant part which is not woody. For example, the stem of a non-wood plant is a non-wood plant part. Woody plants may also have non-wood plant parts, for example stalks, leaves.

"Pulp" refers to a composition comprising primarily of fibres derived from a plant or part thereof, wood or recycled paper, which is to be processed into paper or moulded pulp article(s). Pulp also includes the substantially dry material prepared by chemically or separating fibres from wood, plant material or waste paper. "Straw" refers to the dry stems or stalks of plants. Detailed description of the invention

The pulp composition according to the invention is prepared from non-wood fibres with a diameter from 2.5 to 10 μηη. Secondary characteristics in addition to fibre diameter may also be considered in the selection of fibres. An example comprises further selecting for fibres with a moisture content <12% of its dry weight for preparing the pulp composition. The non-wood fibres may be from a non-wood plant or any non-wood part of a plant or any combination thereof. Examples of plant parts include but are not limited to stems, stalks, leaves, roots and husks or any combination thereof. The non-wood fibres may also be from bagasse or straw. Examples of non-wood plants that may be used for the fibres include but are not limited to sugarcane, grasses, cereal plants, bamboo, palm, coconut, corn, yam, kenaf or any combination thereof. Examples of cereal plants include sorghum, rice, wheat and the like. Either the entire plant or parts of the plant or any combination thereof may be used for preparing the pulp composition (pulping). The pulp composition may also be derived from any combination of plants and/or any combination of plant parts. In particular, the plant or plant part may be part of agricultural waste.

For example, fibres from sugarcane bagasse may be used for preparing the pulp composition.

According to an aspect of the invention, fibres with a diameter from 2.5 to 10 μΐη are selected for pulping into a pulp composition. Conventional pulping methods, including but not limited to mechanical, chemical, thermo-mechanical pulping methods or a combination thereof may be used to prepare the pulp composition.

According to a further aspect, at least one protease is added to the pulp composition. The protease may be selected from the group consisting of. serine proteases, threonine proteases, cysteine proteases, aspartate proteases, metalloproteases and glutamic acid proteases. A combination of proteases may also be used. In particular, the enzyme papain is used. Papain is a cysteine protease from Carica papaya (papaya) or Vasconcellea cundinamarcensis (mountain papaya).

The pulp composition, with or without added protease, may then be moulded into at least one moulded pulp article. Any conventional moulding process may be used for moulding the moulded pulp article(s). If protease was added to the pulp composition, the moulded pulp article comprises at least one exogenous protease impregnated throughout the moulded pulp article.

It was surprisingly found that even without added protease, the moulded pulp article(s) were readily biodegraded and/or composted. In general, the moulded pulp article(s) according to the invention may be biodegraded and/or composted within 45 to 180 days. The biodegradable and/or compostable pulp composition may also be composted. If protease was added to the pulp composition prior to moulding, the compost obtained from biodegradation and/or composting of such moulded pulp article(s) was observed to be finer than compost from biodegradation and/or composting of moulded pulp article(s) without added protease. This is possibly because the protease contributes to a more thorough biodegradation and/or composting process.

According to a further aspect, the invention provides a compost prepared from composting the biodegradable and/or compostable pulp composition and/or the moulded pulp article(s). The compost may be used to improve the structure and/or increase the moisture and water retention of soil, especially in sandy soils and thus also protects against drought and/or provide nutrients to soil. Compost also balances the pH and carbon, nitrogen, phosphorous and potassium (CNPK) of soil. The compost may also cool the surface of soil, helps break up heavy clay soils, restores minerals and micro-nutrients to depleted soils. The compost also helps the formation of aggregates in soil and this increases soil permeability and decreases the need for irrigation and fertilization. Accordingly, the compost may be used as a fertiliser.

Accordingly, the pulp composition and moulded pulp article(s) are biodegradable and/or compostable and thus environmentally friendly. In particular, the moulded pulp article according to the invention is suitable as a disposable product. The disposable moulded pulp article(s) may be used for packaging, for example, packaging for food and/or drinks. The moulded pulp article(s) may also be used for serving food, soups and/or drinks. Examples of moulded pulp articles may be trays, plates, bowls, cups, cutlery, lunch boxes and the like, as illustrated in Figure 1. Trays include trays for food and/or drink packaging, like egg trays (egg carton), wine trays, meat trays and meal trays. Examples of moulded pulp articles for serving include plates (plain or sectioned plates), cups. In addition, lunch boxes, like the claim shell lunch boxes may be used for packaging and/or serving, for example individual portions of meals. Examples of cutlery include forks, spoons, knives and chopsticks.

The biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may also be used as animal feed. The biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be fed directly to animals. Alternatively, the biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be mixed with at least one other conventional animal feed before feeding to animals. Accordingly, the biodegradable and/or compostable pulp composition and/or moulded pulp article(s) may be a source of fibre for animals. Having now generally described the invention, the same will be more readily understood through reference to the following examples which are provided by way of illustration, and are not intended to be limiting of the present invention. EXAMPLES Example 1 Pulping

Sugarcane bagasse may be considered a waste product from for example, sugar manufacturing. Fibres from sugarcane bagasse having a diameter from 2.5 to 10 μιη were selected for pulping. Optionally, after diameter selection, fibres with a moisture content of a moisture content <12% of its dry weight may be further selected for pulping. The fibres were cleaned or washed to remove undesirable particles, such as dirt, sand and the like before pulping.

The cleaned fibres were then transferred to a pulper tank. Typically, the pulper tank comprises a pulping means. The pulping means may comprise a pulp-rig or rotating blades. The first pulping process occurs at a speed of 120 rpm for 32 to 37 minutes. This was followed by a second round of pulping at a rotation speed of 42 rpm for 1.5 to 2.5 minutes. The two rounds of pulping produced a pulp composition in the form of a slurry comprising a thick suspension of "fibrous" solids in a liquid. This pulp composition may then be moulded into at least one moulded pulp article.

Example 2 Preparation of enzyme

Papain may be obtained from the latex of the papaya fruit (Carica papaya) with any conventional method, such as exemplified below. Three or four incisions were made in the fruits with a sharp instrument to a depth of 2 to 3 mm. The latex that exudes from the incisons coagulates rapidly and is collected into a glass container. This latex may be used immediately for extraction of papain or stored at -8 °C under a nitrogen atmosphere till the extraction of papain is required. For extracting the papain, ethylenediamine-tetraacetic acid (EDTA), pH 7.0, was added to the latex to a final concentration of 1 mM and the suspension was kept under nitrogen for 1 hr at room temperature with constant shaking. The suspension was then centrifuged at 12,000 xg for 30 minutes at the ambient temperature.

The supernatant was transferred to a first vessel connected to a second vessel with 30 ml of distilled water. The first vessel was chilled in an ice bath for 72 hours to precipitate the papain. The papain precipitate was pelleted by centrifugation at 12,000 xg for 20 minutes at 0 °C. The pellet comprising papain from this centrifugation was washed three times with an appropriate amount of 1 mM EDTA, ph 7.0 at 4 °C. Centrifugation was performed again at 12,000 xg for 20 minutes to pellet the washed papain. This pellet was dissolved in an appropriate amount of 1 mM EDTA, pH 7.0. This papain solution may be stored at 4 °C till required. The papain was separated from the EDTA through dialysis and the final volume was adjusted to a suitable volume using distilled water, a solution or a buffer before adding to the pulp composition in Example 3.

Example 3 Addition of enzyme After pulping, papain enzyme may be added into the pulp composition in batches. A first batch of 30.5 ml of papain from Example 2 was added into ~ 50,000 ml of pulp composition in a tank. The pulp composition was first stirred at 120 rpm for 32 to 37 minutes, followed by a further stirring at 42 rpm for 1.5 to 2.5 minutes, using the pulp rig. Next, a second batch of 11 ml of papain enzyme from Example 2 was again added into the pulp composition, with stirring at 55 rpm for 7 minutes. The pulp composition comprising papain may then be moulded into at least one moulded pulp article. The papain enzyme may be replaced by any other protease or combination of protease. Different protease amounts may be added in the two batches. Example 4: Moulding

The pulp composition from Example 1 or 2 may then be used for moulding into moulded pulp articles. The moulding process exemplified in this example comprised three steps. The pulp composition was first transferred to a mould. The mould typically comprises two parts with the pulp composition filling the space between the two parts. The two parts of the mould were then pressed together, followed by baking the mould and pulp composition at 170 to 240 °C for 2 to 15 seconds. This step is termed "pre-cooking". After the pre-cooking step, the mould and pulp composition was baked at 170 to 240 °C for a further 5 to 15 minutes. The second step cures the pulp composition, thus forming the moulded pulp article. By building moulds of different specifications, different moulded pulp articles may be produced according to specification.

In particular, it was surprisingly found that for the pulp composition comprising papain or other protease, the moulding process did not inactivate the protease completely. The papain or other protease retains sufficient activity to facilitate the biodegradation and/or composting of the moulded pulp article(s).

Claims

A process for preparing a biodegradable and/or compostable pulp composition comprising the steps of:

(i) providing non-wood fibres;

(ii) selecting fibres having a diameter from 2.5 to 10 μητ,

(iii) preparing a pulp composition from the fibres from step (ii) ·

The process according to claim 1 , wherein the non-wood fibres are from a non-wood plant or non-wood part of a plant or any combination thereof.

The process according to claim 1 or 2, wherein the non-wood fibres are from sugarcane, grasses, cereal plants, bamboo, palm, coconut, yam, corn, kenaf or any plant part thereof or any combination thereof.

The process according to any one of the preceding claims, wherein the plant part comprises bagasse, straw, stems, stalks, leaves, roots, husks or any combination thereof.

The process according to any one of the preceding claims, wherein the non-wood fibres are from sugarcane bagasse.

The process according to any one of the preceding claims, further comprising selecting for fibres with a moisture content < 12% of its dry weight after step (ii).

The process according to any one of the preceding claims, further comprising step (iv) adding at least one protease to the pulp composition.

The process according to claim 7, wherein the protease is selected from the group consisting of: serine proteases, threonine proteases, cysteine proteases, aspartate porteases, metalloproteases and glutamic acid proteases.

9. The process according to claim 7 or 8, wherein the protease comprises papain. 10. The process according to any one of the preceding claims, wherein step (iv) comprises pulping at a speed of 120 rpm for 32 to 37 minutes followed by further pulping at a speed of 42 rpm for 1.5 to 2.5 minutes,

11. The process according to any one of the preceding claims, further comprising moulding the pulp mixture into at least one moulded pulp article.

12. A biodegradable and/or compostable pulp composition prepared by the process according to any one of claims 1 to 10.

13. A biodegradable and/or compostable moulded pulp article prepared according to the process of claim 1. 14. The biodegradable and/or compostable moulded pulp article according to claim 13, comprising at least one exogenous protease impregnated throughout the moulded pulp article.

15. The biodegradable and/or compostable moulded pulp article according to claim 13 or 14, wherein the exogenous protease is selected from the group consisting of: serine proteases, threonine proteases, cysteine proteases, aspartate porteases, metalloproteases and glutamic acid proteases.

16. The biodegradable and/or compostable moulded pulp article according to any one of claims 13 to 15, wherein the protease comprises papain.

17. The biodegradable and/or compostable moulded pulp article according to any one of claims 13 to 16, wherein the moulded pulp article comprises a bowl, cup, plate, tray, egg carton, cutlery or packaging material.

18. A compost obtained by composting the moldable pulp composition according to claim 10 and/or the moulded pulp article according to any one of claims 12 to 16. 9. A fertiliser comprising the compost according to claim 18.

20. Use of the compost according to claim 18 as a fertiliser.

21. Use of the biodegradable and/or compostable pulp composition according to claim 12 and/or the biodegradable and/or compostable moulded pulp article according to any one of claims 12 to 17 as animal feed.