WO2014021725A1

WO2014021725A1 - A method for producing paper with biostatic properties and device for performing this method

Info

Publication number: WO2014021725A1
Application number: PCT/PL2012/000089
Authority: WO
Inventors: Henryk Andrzej FIJAŁKOWSKI; Piotr BLOCH
Original assignee: Apis Spółka Z Ograniczoną Odpowiedzialnością
Priority date: 2012-08-03
Filing date: 2012-09-11
Publication date: 2014-02-06
Also published as: CZ2015122A3; PL400244A1

Abstract

The present invention relates to a method for producing cardboard paper or cardboard itself with biostatic properties based on mixtures of recycled paper or waste paper pulp consists in the fact that the waste paper suspended mass is formed from recycled material in the waste paper preparation system. This suspended mass is ground, purified from contaminants and then dewatered on the wire. The final product is formed into a single- or multi-layer web of paper or paperboard. The web is subjected to a preliminary treatment consisting in drying, the surface sealing and the final stage of drying completely. The method is characterized by that the aqueous suspension of TiO₂ at a concentration of not more than 1 % is applied to the paper web during drying process and forming a coating of TiO₂ with biocidal properties. The invention also provides equipment according to the invention consisting of a line of waste paper preparation equipped with pulper, mills, pumps, sorters and a paper machine equipped with: infusion sieve, press, drying cylinders and rewinder according to the invention.

Description

A method for producing paper with biostatic properties

and device for performing this method

Field of the Invention

The invention relates to a method for producing paper used for the manufacture of cardboard or cardboard itself based waste paper or mixture of waste paper and cellulose. Paper and cardboard obtained by this method is intended to use for manufacturing cardboard packaging in particular - cartons. Due to the technological process of production using very hot media for drying the paper web, obtained paper for manufacturing cardboard or paperboard product is clean, sterile and ready to be processed into final products, such as cardboard packaging. After manufacture, the product is sterile, but during the further processing and everyday use, it is not in any way protected against growth of bacteria and other microorganisms on the surface or within its structure. This is particularly important when the final product is used for packaging products such as food, which should be transported and stored in a free of microorganism environmental.

State of the art

From the description of Polish patent application No P.389158, it is known paperboard with biocidal properties made of layers of paper, characterized in that it has an antimicrobial zone thick not more than 3 mm, containing antibacterial ingredients, such as silver nanoparticles Ag° and/or Cu^*1 ions and/or Zn²⁺ ions. In one embodiment, it is also disclosed a method of obtaining paperboard with biocidal properties made of paper layers. In this method the surface layer is treated with a microemulsion of water in oil, in which water is dispersed phase and the microemulsion contains an antibacterial agent in the form of Ag° ions and/or Cu⁺¹ ions and/or Zn²⁺ ions in an amount of from 5 to 2500 mg/kg of the formulation. The continuous phase is cyclohexane and/or dodecane and/or heptane and/or decane and/or octane in an amount of at least 95% by weight of the formulation. The microemulsion contains stabilizers in an amount up to 10% by weight, such as surfactants with HLB of 3 to 6 such as Bis(2-Ethylhexyl) Sodium Sulfosuccinate and/or polyethylene glycol p-(1 , 1 ,3,3- tetramethylbutyl)-phenyl ether and/or sorbitan mono-oleate and/or sorbitan monostearate and/or co-surfactants, such as isopropanol and/or hexanol, and/or n-butanol and/or n- octanol.

From description of Polish patent application No P.391295 is known a method of making antibacterial paper and device for manufacturing an antibacterial paper, intended especially for the manufacture of sanitary paper. Process for the preparation sanitary paper based on pure cellulose, waste paper, as well as their mixtures according to this invention is that the paper web with a weight of 12-45 g/m² through a drying process on the drying cylinder (at a speed of 300-2000 m/min), is subjected to evenly spray of silver nanoparticles solution at a concentration of greater than 5 ppm. Then the paper is wound on the coil.

The current state of the art also discloses the use of Ti0₂, which most often occurs in the form of powders, solutions or colloidal layers on various mineral substrates such as glass or metal (Chen, X., Mao, S.S., 2007, Chemical Reviews, 107, 2891 -2959). This significantly reduces the possibility of its application. In the prior technology there are also reports on the use of titanium dioxide in the protective coatings on polymers. These coatings are used in order to give the polymer products their photocatalytic, self-cleaning and anti-microbiat properties.

A barrier in the implementation of solutions containing antibacterial ingredients, such as silver nanoparticles Ag° and/or Cu⁺¹ ions and/or Zn²⁺ ions is high manufacturing cost of the final product, in particular cardboard produced on the basis of the desired paper weight in the range 80-160 g/m². The aim of the invention was to develop a technology, which, due to lower substrate costs could generally be used in the paper industry.

Detailed description of the Invention

A method for producing cardboard paper or cardboard with biostatic properties based on mixtures of recycled paper or waste paper pulp according to the invention in which the waste paper suspended mass is formed from recycled material in the waste paper preparation system, then ground, purified from contaminants and dewatered on the wire, next formed into a single-or multi-layer web of paper or paperboard, and subjected to a preliminary treatment consisting in drying, the surface sealing and the final stage of drying completely, characterized in that aqueous suspension of Ti0₂ at a concentration of not more than 1% is applied to the paper or paperboard web during a drying process. And then, after complete drying, it is wound into coil.

Preferably, when of Ti0₂ is applied by spray evenly. The preferred ratio of the anatase and rutile crystalline structure of Ti0₂ is 70:30.

The most preferred is when spraying an aqueous suspension of Ti0₂ is carried out in technological line at the stage of the last drying cylinder, on at least one surface of the paper for the production of cardboard paper or cardboard, using the minimum amount of water to evaporate of the solution from the hot paper web. Preferably, when a speed application of suspension is synchronized with a speed of the paper machine.

The next subject of the invention is the device for the manufacture of paper to the production of cardboard consisting of a line of waste paper preparation equipped with pulper, mills, pumps, sorters and a paper machine, which is equipped with: infusion sieve, press, drying cylinders and rewinder according to the invention, characterized in that it is equipped with a system for mixing and dispensing an aqueous suspension of Ti0₂.

Preferably, when the mixing and dispensing system comprising a dosing and pumping device equipped with a tank with paddle mixer, vibrating spray tube with the fan nozzle system spraying the suspension in the mist form on the paper web surface (or cardboard). Summary of the Invention

The present invention allows to apply Ti0₂ particles to the large surface of the paper web for manufacturing of cardboard or paperboard and it makes possible production of cardboard paper or paperboard with biostatic properties (in the presence of visible light, titanium dioxide releases active oxygen having strong antibacterial activity). Thus, the invention provides ability of obtaining semi-products with improved properties for further processing into cartons with bactericidal function protecting them against the growth of bacteria, viruses and microorganisms, in particular even when they are used in places vulnerable to contamination of the surface. For a better understanding of the solutions below an exemplary embodiment of the invention is presented. The attached drawing provides a better explanation of the invention, whereby:

Figure 1 shows a graph of the antibacterial activity of Ti0₂, at a concentration of 0.8 g/m² and 1 g/m² on Escherichia coli - ATCC25922- results are shown in %, Figure 2 shows a graph of the antibacterial activity of Ti0₂, at a concentration and 0.8 g/m² 1 g/m² on Staphylococcus aureus - ATCC25923 - result are shown in %,

Figure 3 shows a device for producing biostatic paper for biostatic paper for

manufacturing cardboard paper or cardboard in schematic terms.

Example 1

Experiments were performed showing antibacterial activity of cardboard paper covered by a coating containing two different concentrations of titanium dioxide such as 0.8 g/m2 and 1 g/m2. There were indicator bacteria selected: Staphylococcus aureus - ATCC25923

(a representative gram-positive bacteria) and Escherichia coli - ATCC25922 (a representative of Gram -negative bacteria).

Staphylococcus aureus is one of the main components of the flora of human mouth, nose and skin, while a rod-shaped f . coli is a typical representative of the flora of the

gastrointestinal tract of all mammals.

These bacteria colonize (even at low populations) human hands and can lead to contamination of many surfaces such as cosmetic packaging, medicines, hygiene products, etc.

The material for the study were two-coated paper cartons containing two different concentrations of titanium dioxide, such as 0.8 g/m² and 1 /m², uncoated cardboard was used to perform control study

Then the cartons were cut into squares measuring 2cm/2cm, cutting operations performed in a sterile environment (i.e. the laminar airflow and using sterile scissors).

Squares were placed in glass petri dishes (the four squares on one plate - Fig. 1 ), and then on the upper surface containing Ti0₂ were loaded with 500 μΐ of normal saline containing the suspension of indicator strains (indicator strains preparation procedure is given below). Active carefully spread on the upper surface of the test squares, then the plates of the open lid was placed on a windowsill and left at room temperature for 4, 8 and 24 hours. After this time cartons successively thrown into 5 ml of saline. All of them were shaken very carefully for about 2 minutes, and then quantitatively plated using decimal dilutions on appropriate solid growth media i.e. Mac Conkey (Biocorp) and Columbia Agar containing 5% sheep blood (Biocorp). The number of bacteria that grew after 24 hours on a solid media were counted, and the result given as colony forming units per 1 ml (cfu/ml). The results are shown in Table 1 and in Figure 1 and Figure 2.

Table 1. Antibacterial activity of Titanium dioxide onthe indicator bacteria such as Staphylococcus aureus- ATCC25923 and Escherichia-coli -ATCC25922, at two

concentration of Ti0₂: 0.8 g/m² and 1 g/m^2-

The device according to the invention provides even distribution of the Ti0₂ particles in the structure of the paper web. Ti0₂ ensures the production of paper for manufacturing of cardboard or cardboard with biostatic properties at the surface, that protect it from the growth of bacteria, viruses and microorganisms. Example 2

A method for producing cardboard paper or cardboard with biostatic properties based on mixtures of recycled paper or waste paper pulp according to the invention consists in that the waste paper suspended mass is formed from recycled material in the waste paper preparation system, and then ground, purified from contaminants and dewatered on the wire, next formed into a single- or multi- layer web of paper or paperboard, and subjected to a preliminary treatment consisting in drying, the surface sealing and the final stage of drying completely.

Figure 3 shows schematically the process, in which the paper web (1 ) with a weight of 100 g/m², used in the production of cardboard, is subjected to even dispersion spray a suspension in the form of a mixture of Ti0₂, in the drying process on drying cylinders. This suspension is a mixture of water and Ti0₂ at 1% concentration, where Ti0₂ has anatase and rutile crystalline structure in a ratio of 70:30. Then, the paper web - after complete drying - is wound into the coil.

Spraying an aqueous suspension of Ti0₂ is carried out on the last drying cylinder in the technological process, on at least one surface of the cardboard paper with a minimum amount of water to evaporate from the hot paper web. Dosed quantity of the suspension is synchronized with the speed of the paper machine.

Equipment for the producing biostatic cardboard paper consists of waste paper preparation line and papermaking machine. The waste paper preparation system includes devices such as a pulper, mills, pumps, and sorters. These devices are designed to defibering waste paper, removal of impurities, and preparation of fibers to obtain an uniform final pulp with appropriate parameters. Ready mass, an appropriate concentration is supplied to the paper machine. Then, this mass is poured into a sieve by infusion, where the paper web is formed and it is initially dewatered. After the initial dehydration, the paper web (1 ) is further dewatered in two presses. Then begins the process of drying in the tens of drying cylinders. Built surface-size press is located after twenty-cylinder. This press coated paper web by coating composition, gluing it on the surface. Then the coated paper web (1 ) is passed to the next drying cylinders for further evaporation of water from the web. The heated drying cylinders inflate the hot air, which is dried paper web to the desired level. At the level of the last drying cylinders, the paper web is sprayed suspension of Ti0₂. Ti0₂ suspension is a mixture of water and Ti0₂ with concentration no greater than 1%. Ti0₂ has anatase and rutile crystalline structure in a ratio of 70:30. The mixture is suitably prepared in the mixing and dispensing system.

Mixing and dispensing system consists of a dosing pump unit equipped with tanks with stirrers paddle 4,6. Further includes a vibrating spray tube 2 with the fan nozzles system 3, spraying the suspension in the mist form on the paper web surface. Dosing and pumping device, transmit water at a suitable temperature (using terminals supplying hot and cold water). Suitable temperature of water is achieved by temperature control valve 9 to the tank 6 with the paddle 8, where thoroughly is mixed Ti0₂ (of anatase and rutile a crystalline structure, in a ratio of 70:30) form a container for the medium 4 with a stirrer 8 and water. The thorough mixing in the tank 6, allows to obtain a suitable suspension - ready for application. Suspension at a suitable temperature and pressure is fed into the spray tube 2 with the comprising arrangement of two drizzle nozzles 3, spraying the suspension in the mist form on the paper web surface 1. The suspension is fed through a hose connecting the vibrating device with spray tube 2. Then paper web is wound on the winder coil, after completely dry. At this stage the product is ready for further processing to carton.

Temperature and pressure of suspension is maintained by thermo-manometer 10 and control valve of temperatur 9 and automatic pressure maintenance a spray suspension through a dosing pump 6.

Claims

1 . A method for producing cardboard paper or cardboard with biostatic properties based on mixtures of recycled paper or waste paper pulp according to the invention consists in which the waste paper suspended mass is formed from recycled material in the waste paper preparation system, then ground, purified from contaminants and dewatered on the wire, next formed into a single-or multi-layer web of paper or paperboard, and subjected to a preliminary treatment consisting in drying, the surface sealing and the final stage of drying completely, characterized in that aqueous suspension of Ti02 at a concentration of not more than 1% is applied to the paper or paperboard web during a drying process, and forming a coating with biocidal properties.

2. The method according to claim 1 , characterized in that Ti0₂ is applied by spray evenly.

3. The method according to claim 1 , characterized in that ratio of the anatase and rutile crystalline structure of Ti0₂ is 70:30.

4. The method according to claim 1 , characterized in that spraying an aqueous

suspension of Ti0₂ is carried out to at least one surface of the cardboard paper in the technological line of the last drying cylinder, using a minimum quantity of water to evaporate of the solution from the hot paper web.

5. The method according to claim 4, characterized in that a speed application of

suspension is synchronized with a speed of the paper machine.

6. The device for the manufacture of paper to the production of cardboard consisting of a line of waste paper preparation equipped with pulper, mills, pumps, sorters and paper machine, which is equipped with: drying cylinders, sieve, press and rewinder according to the invention, characterized in that it is equipped with a system for mixing and dispensing an aqueous suspension of Ti0₂.

7. The device claim 6, characterized in that mixing and dispensing system which is dosing and pumping device is equipped with a tank (6) with paddle mixer (8), vibrating spray tube (2) with the fan nozzle system (3) spraying the suspension in the mist form on the paper web surface (1 )