ANTIMICROBIAL PAPER COATING

Description

[0001] The present invention relates to a biocidal coating of paper for printing.

[0002] The problem of limiting the spread of microorganisms, namely those pathogenic to a human being, has became extremely important at the end of the twentieth century as there is increase of bacteria population resistant to many antibiotics and as a result of faster and more often contacts of the human beings from remote corners of the planet. Control of microorganisms growth on a paper is of high importance as on the one hand a paper is still a base of many documents (including banknotes), and - on the other hand - material of which paper is made is a medium for many microorganisms.

[0003] One of method of microorganisms control is utilization of characteristics of nanomaterials (nanoparticles) of various compounds, most often oxides of metals (zinc oxide, titanium oxide, magnesium oxide, copper, copper oxide, cadmium selenide, cadmium telluride) or metals (silver, gold). In the state of art there are well known many solutions based mainly on nanosilver. Starch content in a paper coating mixture is often avoided or decreased to enhance effectiveness. Maintenance of printability on such paper is crucial.

[0004] In the patent literature there is Japanese description JP1996337078, from which one can learn about antibacterial coating containing, admittedly, titanium white, but silver in form complexed salts is the chief anti-microorganisms ingredient. The Japanese description mentions a high content of starch in coating mixture. The US patent application description US20150086598 reveals a solution utilizing nanoparticles of titanium oxide to achieve anti-microorganisms activity, where the oxide content must be 5 or more percentages by mass of a paper coating mixture. In the description starch is not cited.

[0005] The biocidal coating of paper for printing according to this invention, containing titanium oxide nanoparticles, salts of mono-, bi- and trivalent metals, polyvinyl alcohol, starch, aliphatic polyamine and sodium aluminosilicate characterises by that their proportions are as follows:

Ingredient	Percentage by mass of each ingredient [%]	Tolerance
Titanium oxide	3.92%	+-40%
Salts of metals (I, II and III- valent)	14.68%	+-40%
Starch + PVOH	68.86%	+-40%
Aliphatic polyamine	6.27%	+-40%
Sodium aluminosilicate	6.27%	+-40%

and biocidal activity of this mixture does not require activation by UV rays.

[0006] Unexpectedly, the paper coating containing starch and titanium white nanoparticles with other components added at proper ratio, is as good as antibacterial papers using silver salts, maintaining excellent characteristics for offset, laser or inkjet printing.

[0007] In studies on biocidal effectiveness of paper coatings basing on challenge with Escherichia coli the following findings of bacterial growth revealed:

• paper coated with standard adhesive layer utilized by Arctic Paper Kostrzyn - 40% (minus indicates that number of bacterial colonies grew, not reduced during the experiment - it means that it was a culture medium for them);
• paper coated with ammonium chloride +8% - reduction of E. coli bacterial vitality by 8%
• paper coated with a mixture NaCl+CaCl₂+ 22%
• paper coated with N-vinyle amine (Catiofast) +13%
• paper coated with PAX +19%
• paper coated with PVA + 5%
• paper coated with starch and 1.5-% TiO₂ +30%.

[0008] In the undermentioned embodiment of preparation of the biocidal coating of paper for printing shows only one of the possibilities, without limiting protection range: Composition of coating mixture:

Ingredient	Commercial name	Amount of dry substance in g/100g of the mixture	Percentage by mass of each ingredient [%]	Tolerance
Titanium oxide	Titanium white	0.53	3.92%	+-40%
Sodium aluminosilicate	Zeolit (Zeocros PF)	0.84	6.27%	+-40%
Sodium chloride	Sól warzona [Evaporated salt]	0.18	1.31%	+-40%
Ammonium chloride	Ammonium chloride	0.18	1.31%	+-40%
Calcium chloride	Calcium chloride	1.58	11.76%	+-40%
Polyvinyl alcohol	PVOH BP-05	1.25	9.31%	+-40%
Aliphatic polyamine	Catiofast 160	0.84	6.27%	+-40%
Native and cationic starch	Merizet 120	8.00	59.55%	+-40%
Polyaluminum chloride	PAX 18	0.04	0.31%	+-40%

Biocidal activity of the coating according to the invention extends on bacteria, bacteriophages and viruses.

[0009] The coating according to the invention is applied one- to both sides on a sheet with standard technologies used by paper industry. Paper covered with the coating maintains excellent characteristics for offset laser and inkjet printing. It can be used for printing of books, prospectuses, prescription pads, labels, office printings and everywhere where there is recommended to brake infection transmission chain, that is when many persons contact with the surface of printed paper coated according to the invention. Possibility of application of the coating on surfaces contacting with food is an additional advantage. The ingredients of the coating disintegrate without contamination of environment.

[0010] Not without significance is economic factor - majority of antibacterial papers utilises nanosilver, which is more expensive than titanium white.

Claims

1. The biocidal coating of paper for printing according to this invention, containing titanium oxide nanoparticles, salts of mono-, bi- and trivalent metals, polyvinyl alcohol, starch, aliphatic polyamine and sodium aluminosilicate characterised in that their proportions are as follows:

Ingredient	Percentage by mass of each ingredient [%]	Tolerance
Titanium oxide	3.92%	+-40%
Salts of metals (I, II and III- valent)	14.68%	+-40%
Starch + PVOH	68.86%	+-40%
Aliphatic polyamine	6.27%	+-40%
Sodium aluminosilicate	6.27%	+-40%

and biocidal activity of this mixture does not require activation by UV rays.