PL225010B1 - Polyethylene composite with bactericidal properties - Google Patents

Description

Description of the invention

The subject of the invention is a polyethylene composite with bactericidal properties. The polymer matrix of the composite is polyethylene, and the bactericidal agent is copper silicate modified with polyhedral oligomeric silsesquioxane, used in the production of a special type of packaging for the food and medical industry.

The production of composites is a physical modification of polymers and is aimed at developing a material with strictly planned / defined properties. The main goal of the production of composite materials is to improve its mechanical, thermal, processing properties, etc. One of the directions of research currently being carried out is the search for polymeric materials with bactericidal properties, the use of which is interested, among others, in the food and packaging industry, the pharmaceutical industry and the automotive industry (means of transport public).

In the world literature, there are no reports on polyolefin composites in which the bactericidal agent is modified with a polyhedral oligomeric silsesquioxane, copper silicate (CuO-SiO ₂ ) nanofiller.

The most commonly used polymeric filler with bactericidal properties is currently nanosilver, but the price of this type of filler and the composite produced with it is very high. The world literature describes the addition of silver in the form of nanosilver for the production of food contact packaging. However, in a 2011 publication in the journal Food Additives and Contaminants, H. Song et al. In an article titled "Migration of silver from nanosilver-polyethylene composite packaging into food stimulants" proved that nanosilver added to polymer composites can leak from the food and drink packages thus produced. As a consequence, it can lead to the accumulation of silver in the human body and cause very serious diseases.

In the literature, copper oxide is often described as a filler with bactericidal and fungicidal properties. For example, in 2005 in the journal Chemistry of Materials, N. Cioffi et al. In an article entitled "Copper nanoparticle / polymer composites with antifungal and bacteriostatic properties" described the advantages of a copper-polymer composite, which was characterized by very good antibacterial properties in relation to bacteria E. Coli and Staph. aureus. The disadvantage of using pure copper oxide, described in the cited publication, is the high cost of obtaining a pure filler as well as the lack of its bonding in the matrix.

The antibacterial properties of a polymer composite with the use of copper silicate as a filler were first described in 2012 in the journal Bioelectrochemistry by M. Nowacka et al. In the article entitled "Electrokinetic and bioactive properties of CuO-SiO ₂ oxide composites", the authors described the properties of composites made of polyester resins and copper silicate. They used a strain of Pseudomonas Aeruginosa for bactericidal studies. The produced composites were characterized by bactericidal properties in every range of the amount of filler used.

So far, no antibacterial properties of a polymer composite with the use of copper silicate modified with nanofill of polyhedral oligomeric silsesquioxane have been described in the literature.

The essence of the invention is a polymer composite with bactericidal properties, characterized in that the composite is a matrix and a filling, the matrix is preferably made of polyethylene, and the filling is copper silicate modified with a nanofiller of the monohydroxypropyl dimethylsiloxyheptaisobutylsilsesquioxane POSS of the formula

The content of which is from 0.1 to 40% by weight, preferably from 2 to 8% by weight, the amount of POSS nanofiller used for the modification, based on the copper silicate, from 0.1 to 50 parts by weight, preferably from 1 to 15 parts by weight.

Preferably, the polyethylene matrix is: ultra-low-density polyethylene - PE-ULD or linear low-density polyethylene - PE-LLD, or medium-density polyethylene - PE-MD, or high-density polyethylene - PE-HD, or polyethylene with high molecular weight and high density - PE-HD HMW, or ultra high molecular weight polyethylene - PE-UHMW, or metallocene polyethylene - mPE, or mixtures thereof.

Thanks to the solution according to the invention, the following technical and operational effects were obtained:

- the produced composites can be processed with standard techniques currently used in plastics processing (extrusion, injection, etc.);

- composites are characterized by bactericidal properties against the bacteria Pseudomonas aeruginosa;

- the produced composites show an improvement in mechanical properties in relation to the input polymer material (polyethylene), including: Young's modulus, strength, Shore hardness;

- possibility of multiple processing - material recycling;

- utilization through energy recycling;

- waste-free production - all shortages arising during the production of the final product can be returned to the technological process;

- directly to the extruder charging system and recycle;

- wide application possibilities:

packaging industry, food industry, automotive industry, medical industry.

The invention in an exemplary embodiment has been illustrated in the drawings, where Fig. 1 shows the relationship between the Young's modulus, composites with bactericidal properties formed on the PE-LD matrix, on wt.%. filler content (CuO-SiO ₂ -Bu POSS), Fig. 2 shows the relationship between the elongation of composites with bactericidal properties formed on the PE-LD matrix and wt. filler content (CuO-SiO ₂ -Bu POSS), Fig. 3 shows the dependence of the Shore hardness of composites with bactericidal properties formed on the PE-LD matrix, on wt. filler content (CuO-SiO ₂ -iBu POSS), and Table 1 shows the bactericidal properties of reference samples and composites - tests carried out for Pseudomonas Aeruginosa.

A polyethylene composite with bactericidal properties can be produced in a technological process ensuring a high degree of homogenization of copper silicate in the polymer. The homogenization process, in the plasticized state of the polymer, can be carried out using a single or twin-screw extruder, batch mixer, etc. The homogenization process should be carried out at temperatures typical for polyethylene processing (from 130 to 230 ° C).

The method of preparing the filler (copper silicate) was described in 2012 in the journal Bioelectrochemistry by M. Nowacka et al. The authors of the article entitled "bioactive and electrokinetic properties of CuO-SiO ₂ oxide composites' and the earlier Polish patent Theophilus and other Jesionowskiego No P.390326" method for preparing a composite oxide of CuO-SiO ₂ from the waste solutions of galvanic sulfate (VI), copper ( II) and sodium silicate ".

On the other hand, the modification process was described in the earlier Polish patent application P-394904. The copper silicate modification process was carried out using 1- (3-hydroxypropyl) dimethylsiloxy-3,5,7,9,11,13,15-hepta (isobutyl) pentacyclo- [9.5.1.1 ³ ' ⁹ .1 ⁵ ' ¹⁵ .1 ^{7 '13]} oktasiloksanu hereinafter iBu POSS (POSS nanofiller) having a molecular formula: C ₃₃ H ₇₆ O ₁₄ Si ₉ and a molecular weight: 949.72. The structural formula is shown below

PL 225 010 B1

The invention includes a polymer composite with bactericidal properties, characterized in that the matrix of the composite is polyethylene, and the filling is a bactericidal agent (copper silicate modified with iBu POSS nanofiller), the content of which is from 0.1 to 40% by weight, preferably from 2 to 8% by weight. by weight. The amount of nanofiller of the polyhedral oligomeric silsesquioxane type used for the modification, based on the copper silicate, may be 0.1 to 50 parts by weight (part by weight), preferably 1 to 15 parts. wt. In the following part of the study, the modified monohydroxypropyl dimethylsiloxyheptaisobutylsilsesquioxane copper silicate (bactericidal agent) will be designated as: CuO-SiO ₂ -Bu POSS.

The following can be used as polyethylene: PE-ULD - ultra-low-density polyethylene, PE-LLD - linear low-density polyethylene, PE-MD - medium-density polyethylene, PE-HD - high-density polyethylene, PE-HD HMW - polyethylene with high molecular weight (mass) and high density, PE-UHMW - ultra high molecular weight (mass) polyethylene, mPE - metallocene polyethylene and mixtures of the above-mentioned polyethylenes; as well as mixtures of the above-mentioned polyethylenes and ethylene copolymers.

The following examples illustrate the invention.

P r z k ł a d I

Low-density polyethylene (PE-LD) was homogenized with 40% by weight of 10-part modified copper silicate. wt. 1- (3-hydroxypropyl) dimethylsiloxy-3,5,7,9,11,13,15-hepta (isobutyl) pentacyclo [9.5.1.1 ^3.9 .1 ^5.15 .1 ^7.13 ] octasiloxane (iBu POSS) (CuO-SiO _2- iBu POSS) in a batch mixer, at 160 ° C, with the rotor speed of the mixer rotors being 20 rpm. The mixing process was carried out until a constant torque of the mixer was established - about 7 minutes. Before homogenization, the modified copper silicate was dried in a forced circulation dryer at a temperature of 110 ° C. The resulting composite was ground using a slow-speed grinder. Then the concentrate with a content of 40 wt. of the modified silicate was diluted to a concentration of 2 wt.%. CuO-SiO _2- iBu POSS in the twin-screw extrusion process with cold granulation - the head temperature was 190 ° C. Composite, in the form of granules, with a content of 2 wt. CuO-SiO _2- iBu POSS was processed in the injection process. Measurement paddles were manufactured in accordance with the applicable standard (type 1A), which were used to assess the basic strength parameters. It was found that the addition of 2 wt. filler did not cause significant changes in the stiffness of the composite. The composite's modulus of longitudinal elasticity is 206.67 ± 4.37 MPa, in the case of PE-LD the value of E = 208.33 ± 4.62 MPa - changes in the value of E within the determined measurement errors (corrected standard deviation value). 2 wt.% Addition of the filler caused a reduction in the relative elongation at break of the composite (s _b ), in relation to PE-LD. The relative elongation for PE-LD was 74.56 ± 2.51%, in the case of the s _b composite it dropped to the value of 65.96 ± 2.47%. The addition of 2% filler also increases the hardness of the composite by 7.44% in relation to PE-LD. The Shore hardness of the composite was 40.40 ± 0.52 °, while for PE-LD it was 37.60 ± 0.70 °. A graphic summary of the determined basic strength parameters of the composite and polyethylene (composite matrix) is presented in the figures below: 1) Modulus of longitudinal elasticity (E); 2) Relative elongation at break (e _b ); 3) Shore Shore hardness. The obtained systems were submitted to bacteriostatic tests using the opportunistic gram-negative bacterium Pseudomonas aeruginosa, the method described in 2001 in the journal Methods in Enzymology by L. Thi and others in the article entitled "First stages of biofilm characterization and quantification of bacterial functions involved in colonization process" the results are summarized in Table No. 1. A significant reduction in bacterial adhesion was observed

PL 225 010 B1

Pseudomonas aeruginosa to the surface of copper silicate modified polyethylene. This addition will begin to reduce the surface biofilm formation of the composite from multiple colonies to single cells. This proves the strong bacteriostatic effect of the described composite.

P r z x l a d II

Low-density polyethylene (PE-LD) was homogenized with 40% by weight of 10-part modified copper silicate. wt. iBu POSS (CuO-SiO ₂ -iBu POSS) under the conditions as above. The resulting composite was ground using a slow-speed grinder. Then the concentrate with a content of 40 wt. of the modified silicate was diluted to a concentration of 4 wt.%. CuO-SiO _2- iBu POSS in the twin-screw extrusion process with cold granulation - the head temperature was 190 ° C. Composite, in the form of granules, with a content of 4 wt. CuO-SiO _2- iBu POSS was processed in the injection process. Measurement paddles were manufactured in accordance with the applicable standard (type 1A), which were used to assess the basic strength parameters. It was found that the addition of 4% filler did not cause any significant changes in the stiffness of the composite. The composite's modulus of longitudinal elasticity is 206.60 ± 6.02 MPa, in the case of PE-LD the value of E = 208.33 ± 4.62 MPa - changes in the value of E within the determined measurement errors (corrected standard deviation value). The addition of 4% filler reduced the relative elongation at break of the composite (s _b ) in relation to PE-LD. The relative elongation for PE-LD was 74.56 ± 2.51%, in the case of the s _b composite it dropped to the value of 63.84 ± 2.56%. The addition of 4% filler also increases the hardness of the composite by 8.24% in relation to PE-LD. The Shore hardness of the composite was 40.70 ± 0.48 °, while for PE-LD it was 37.60 ± 0.70 °. A graphic summary of the determined basic strength parameters of the composite and polyethylene (composite matrix) is presented in the figures below: 1) Modulus of longitudinal elasticity (E); 2) Relative elongation at break (s _b ); 3) Shore Shore hardness. As with the samples of Example 1, the samples of Example 2 had similar bacteriostatic properties, the results are shown in Table 1.

P r x l a d III

Low-density polyethylene (PE-LD) was homogenized with 40% by weight of 10-part modified copper silicate. wt. iBu POSS (CuO-SiO ₂ -iBu POSS) under the conditions as described in Example 1. The resulting composite was milled using a low-speed mill. Then the concentrate with a content of 40 wt. of the modified silicate was diluted to a concentration of 8 wt.%. CuO-SiO _2- iBu POSS in the twin-screw extrusion process with cold granulation - the head temperature was 190 ° C. Composite, in the form of granules, with a content of 8 wt. CuO-SiO _2- iBu POSS was processed in the injection process. Measurement paddles were manufactured in accordance with the applicable standard (type 1A), which were used to assess the basic strength parameters. It was found that the composite longitudinal elasticity modulus amounts to 230.00 ± 9.49 MPa, which is about 10.40% of its value increase in relation to the initial polyethylene - 208.33 ± 4.62 MPa. The addition of 8% filler reduced the relative elongation at break of the composite (s _b ) in relation to PE-LD. The relative elongation for PE-LD was 74.56 ± 2.51%, in the case of the s _b composite it dropped to the value of 60.44 ± 1.16%. The addition of 8% filler also increases the hardness of the composite by 8.77% in relation to PE-LD. The Shore hardness of the composite was 40.90 ± 1.37 °, while for PE-LD it was 37.60 ± 0.70 °. A graphic summary of the determined basic strength parameters of the composite and polyethylene (composite matrix) is presented in the figures below: 1) Modulus of longitudinal elasticity (E); 2) Relative elongation at break (s _b ); 3) Shore Shore hardness. As with the samples from Examples 1 and 2, the samples from Example 3 showed similar bacteriostatic properties, the results are shown in Table 1.

Claims (2)

1. Polymer composite with bactericidal properties, characterized in that the composite is a matrix and a filling, the matrix is preferably made of polyethylene, and the filling is copper silicate modified with a nanofiller of the monohydroxypropyl dimethylsiloxyheptaisobutylsilsesquioxane POSS of the formula The content of which is from 0.1 to 40% by weight, preferably from 2 to 8% by weight, the amount of POSS nanofiller used for the modification, based on the copper silicate, from 0.1 to 50 parts by weight, preferably from 1 to 15 parts by weight. 2. A composite according to claim The method of claim 1, characterized in that the polyethylene matrix is: ultra-low density polyethylene - PE-ULD or linear low density polyethylene - PE-LLD, or medium density polyethylene - PE-MD, or high density polyethylene - PE-HD, or high molecular weight polyethylene - PE -HD HMW, or ultra-high molecular weight polyethylene-PE-UHMW, or metallocene polyethylene-mPE, or mixtures thereof.