SK362023U1 - Composite material from paper mill sludge, starch glue and cork pulp, method of its preparation and its use - Google Patents

Abstract

The composite material from paper sludge, starch glue and cork pulp/granulate is prepared by mixing 20-40% by weight of dry paper sludge, ground into a fraction with a grain diameter of up to 5 mm, with 1-20% by weight of cork granulate with a grain diameter in the range of 1 - 4 mm, 25-60% by weight of water and 5-40% by weight of starch glue. The resulting mixture is then dosed into a pressing matrix with rests, which after dosing is closed to a pressing pressure of 0.1-6.0 MPa with simultaneous heating to 100-140 °C for a period of 10-30 min. Subsequently, the compact is removed from the pressing matrix and dried at a temperature of 100-120 °C for 1 to 7 hours. The composite can replace expanded polystyrene in the transportation of objects and goods, in the construction industry it can be used for the production of sandwich panels, as well as relief decorative boards, parts of furniture or solitary interior objects.

Description

The field of technology

The technical solution falls under the area of woodworking and pulp and paper industry and concerns the use of paper sludge and cork pulp for the production of composite material.

Current state of the art

Packaging systems and their components - e.g. fillers for packaging - they are mostly disposable in nature, their life cycle is usually short, after use they go into the waste and should be recycled. The mentioned packaging, packaging systems, etc. they are perceived as an environmental burden, but society cannot do without them.

A typical example of a material used in packaging systems is expanded polystyrene (EPS). The use of EPS has many advantages, as it is a light, flexible material that is easy to divide and can be used to produce shaped products by pressing, which allows it to be used, for example, in for fixing filler fittings in the so-called packaging filling polystyrene, further for decorative relief parts and sandwich panels for walls in the interior, etc. There are several types of EPS differing in density, and this affects the properties of EPS, e.g. for compressive strength (British Plastics Federation: Expanded Polystyrene (EPS), 2022, https://www.bpf.co.uk/plastipedia/polymers/expanded-andextruded-polystyrene-eps-xps.aspx).

On the other hand, polystyrene (not only EPS) also has negatives. Since it is non-degradable in nature, after use it represents an ecological burden. Although EPS can be recycled multiple times, it is only if it is clean enough (Opady Portal: Even polystyrene can be recycled. How to properly sort polystyrene waste?, 2021, https://www.odpady-portal.sk/Dokument/106034 /even-polystyrene-can-be-recycled-as-polystyrene-waste-properly-sorted.aspx).

One of the solutions to replace EPS is the PSC composite presented here, which consists of paper sludge, cork pulp and starch glue, and whose density and proportional representation of its individual components can be varied, which will ensure different resulting mechanical properties of the PSC composite, similar to that of EPS.

Paper sludge is a process waste from paper production that contains fibers too short to be fed back into the papermaking process at the paper mill. In 2003, more than 4.7 million were produced in Europe alone. tons of paper sludge (in the countries associated with the Confederation of European Paper Industries - CEPI), most of which is landfilled (69%) or incinerated (Likon M.: Recent Advances in Paper Milí Sludge Management. In: Industrial Waste (book), 2012 , https://www.researchgate.net/publication/221927329_Recent_Advances_in_Paper_Mill_Sludge_Management). In most cases, paper sludge ends up pointlessly in landfills as "other waste" and represents an environmental burden. Paper sludge is characterized by considerable hardness and strength if it is dried to the level of average air humidity.

In order to examine the current state of the art, CVTI Bratislava conducted a State of the Art Search in the Espacenet and Patbase databases on January 16, 2023. Based on a search using the keywords: paper sludge, cork, composite, filler, sandwich board, paper-mill-sludge , cork, composite, infill, sandwich panel, the following documents with a similar subject of protection were found:

US2011136182A1 (DANISCO US INC) 2011-04-13

GB437458A (EDWIN WILLIAM STANLEY PRESS) 1935-10-30

CN101041725A (CHEN SHUYI [CN] MINDUO CHEN) 2007-09-26

WO2012035515A1 (CANTI MAX [IT]) 2012-03-22

EP2698417A1 (REVITA BIO SP Z O O [PL] 2014-02-19

JPS5749549A (UNIV MICHIGAN TECH [US]) 1982-03-23

CZ3407U1 (KIESWETTER LUDEK [CZ]) 1995-06-05

US2007027234A1 (CHEMTURA CORP [US]) 2007-02-01

EP2143695A1 (RECUPERI IND SRL [IT] RECUPERI IND SRL) 2010-01-09

CN 1830646A (CHEN MINDUO [CN]) 2006-09-13.

The essence of the technical solution

The proposed material is a composite, consisting of paper sludge, starch glue, and cork dust/granulate - abbreviated PSC composite, P from English. Paper-mill-sludge, S from Eng. Starch-glue (starch glue), and C from English. Cork.

The method of producing the PSC composite is to mix dry paper sludge, ground into fraction s

SK 36-2023 U1 with a grain diameter of up to 5 mm with cork crumb/granulate of various fractions, but with the smallest permissible grain diameter of 1 mm and the largest permissible grain diameter of 4 mm; then with water, and finally with starch glue, in amounts falling within the intervals of mass percentages given for the individual components of the PSC composite (table 1):

Tab. 1: PSC composite - the composition of the composite mixture for its subsequent processing (source: authors).

PSC composite - composition Dry paper sludge (fraction with grain diameter up to 5 mm) Starch glue Cork (fraction 1-4 mm) Water range: 20-40% wt. 5-40% wt. 1 - 20% wt. 25 - 60% wt.

A mixture is created - PSC composite, which is subsequently applied (dosed) into a pressing matrix with supports, which after dosing is closed to a pressing pressure of 0.1 - 6.0 MPa under simultaneous heating of 120 °C, for a period of 10 - 30 min. Subsequently, the compact is removed from the pressing matrix and placed in a dryer with suction for a period of - 1 to 7 h to dry at a temperature of 100 °C so that the humidity of the compact equals the humidity of the surrounding air.

After drying (evaporation of the water present to the level of average air humidity) and hardening of the adhesive, the material is characterized by partial elasticity, good strength and resistance to impact. Changes in the quantitative ratio of individual components of the said composite according to tab. 1, it is possible to regulate its resulting properties, e.g. density, flexibility and strength.

Such a composite can be used e.g. for applications where polystyrene (EPS) was mainly used until now. Unlike polystyrene, which is not degradable in nature and is burned in a waste incinerator or landfilled after its useful life, PSC composite is fully recyclable and also biodegradable, e.g. composting.

The surface of the product made of the mentioned material can be without surface treatment, or it can have a surface treatment in the form of a protective coating, spray or coating, which can be transparent, colored, resistant to moisture, precipitation or pressure water, or resistant to elevated temperatures.

The advantage of the PSC composite is its easy formability in a moist or wet state, which enables the production of moldings even at low pressing pressures. This material, if it is in a dry state, can also be chipped.

Overview of images on drawings

The product according to the utility model will be explained in more detail in the photos, where the detailed structure and consistency of the PSC composite is shown in Figure 1.

Figure 2 shows a molded protective corner made of PSC composite, produced in one molding cycle.

Implementation examples

The protective corner made of PSC composite consists of paper sludge ground in a dry state into a fraction with a grain diameter of up to 5 mm (150 g - 28 wt %), starch glue (200 g - 37 wt %), cork crumb/granulate in fraction 2 -4 mm (35 g - 7 wt %), and water (150 g - 28 wt %) added for processing the composite mixture. The method of producing a protective corner is to mix dry paper sludge, ground into a fraction with a grain diameter of up to 5 mm, with cork crumbs/granules in a fraction of 2-4 mm, then with water, and finally with starch glue. Mixing with a mechanical stirrer takes place in a suitable container, e.g. sheet metal, and it is only necessary to prepare such an amount of the composite mixture that will be processed for the production of products from the said mixture within a few minutes, because the starch glue present in the mixture can dry quickly. The evenly mixed mixture is then applied (dosed) into a pressing matrix with stops, which after dosing is closed to a pressing pressure of 0.5 MPa under simultaneous heating of 120 °C for a period of 10 min. Subsequently, the compact is removed from the pressing matrix and placed in a dryer with suction for 5 hours to dry at a temperature of 100 °C so that the humidity of the compact equals the humidity of the surrounding air. After drying, the product can still be mechanically processed, cleaned of impurities, surface treated with paint or coating. After that, the product is finished and ready for use.

SK 36-2023 U1

Industrial applicability

PSC composite material can be used as a substitute for expanded polystyrene (EPS) in applications in the transportation of objects and goods, as well as in construction and design, where it can be used for the production of sandwich 5 panels, for various decorative applications in the form of decorative relief panels, e.g. for wall coverings. Design applications in the form of solitary interior objects are also possible. The mentioned material can be used for applications where products made from it will not come into contact with pressurized water or rainwater.

Claims (6)

1. Composite material from paper sludge, starch glue and cork crumb/granulate, characterized by the fact that it is formed by a mixture of paper sludge in the range of 20-40% by weight of the mixture, starch glue in the range of 5-40% by weight of the mixture, cork crumb/granulate in the range of 1 - 20% of the weight of the mixture and water in the range of 25 - 60% of the weight of the mixture. 2. Composite material from paper sludge, starch glue and cork crumb/granulate according to claim 1, characterized in that the cork crumb/granulate has a grain diameter in the range from 1 to 4 mm. 3. The method of preparing a composite material from paper sludge, starch glue and cork dust/granulate according to claim 1, characterized in that the paper sludge, which is dried and ground into a fraction with a grain diameter of up to 5 mm, is mixed with with cork crumbs/granules in a fraction with a grain diameter in the range of 1-4 mm, then with water, and finally with starch glue. 4. A method of producing moldings from a composite material prepared by the method according to claim 3, characterized in that the mixed mixture is applied/dosed into a pressing matrix with abutments, which closes after dosing to a pressing pressure of 0.1-6.0 MPa with simultaneous heating 100 - 140 °C, for 10 - 30 min., then the compact is removed from the pressing matrix and placed in a dryer with suction for a period of - 1 to 7 h for further drying at a temperature of 100 - 120 °C. 5. A method of recycling composite material prepared by the method according to claim 3 or 4, characterized in that the used composite in the form of a molding or its parts, or a composite not yet used for the production of a molding, is ground into a fraction with a grain diameter of up to 5 mm, mixed with water and re-pressed. 6. Use of a composite material from paper sludge, starch glue and cork crumb/granulate, obtained by the method according to claim 3, in the production of fixing fillings as a substitute for expanded polystyrene filling, in the production of sandwich panels, in the production of decorative relief panels, e.g. for wall coverings, and in the production of solitary interior objects.