CN118109013A - Modified antibacterial LLDPE material, preparation method thereof and refrigerator - Google Patents

Abstract

The invention discloses a modified antibacterial LLDPE material, a preparation method thereof, an antibacterial water pipe and a refrigerator, and belongs to the field of refrigerator materials. Comprises modified LLDPE resin, composite antibacterial master batch and antioxidant; the molecular chain of the modified LLDPE resin is grafted with maleic anhydride molecules, and the modified LLDPE resin is filled with barium sulfate and calcium carbonate; the particle size of the barium sulfate is selected from any value of 6250-8000 meshes, and the content of free barium ions is lower than 10mg/kg; the composite antibacterial master batch comprises a phosphate glass silver-loaded antibacterial agent, a lubricant and a compatibilizer; the D98 of the phosphate glass silver-loaded antibacterial agent is less than 40 mu m; the compatibilizer is a siloxy terminated polyethylene. The invention is applied to the aspect of refrigerator water pipes with ice making and drinking functions, solves the problems that the traditional LLDPE plastic water pipe for the refrigerator has the defects of bacteria resistance, poor temperature resistance, yellowing of the water pipe and easy precipitation of an antibacterial agent at a die, and has the characteristics of bacteria resistance, high temperature resistance and effective inhibition of the precipitation of the antibacterial agent.

Description

Modified antibacterial LLDPE material, preparation method thereof and refrigerator

Technical Field

The invention belongs to the field of refrigerator materials, and in particular relates to a modified antibacterial LLDPE material, a preparation method thereof, an antibacterial water pipe and a refrigerator.

Background technique

More and more high-end refrigerators for export are equipped with ice-making and drinking water functions. In the process of drinking water flowing from the tap to the ice maker, the water pipe is the component with the largest contact area among the components through which the water flows. The water filter configured in the refrigerator product has an activated carbon microporous filter membrane inside, which is mainly used to remove disinfection byproducts, pesticides and other micropollutants in the water, but has no descaling function. After long-term use of the water pipe, some scale impurities will accumulate in the pipe, and microorganisms will attach to the surface. When the water flow is slow or stops, the microorganisms attached to the inner wall will evolve into bacteria, and after a period of time, they will multiply to form a bacterial colony, affecting the safety quality of the water, and may further affect the safety of the water and ice cubes used by users for drinking.

At present, the most common practice in the refrigerator industry is to use antibacterial materials for ice-making components. In addition, drinking water can also be sterilized to ensure its safety, mainly including chemical sterilization and physical sterilization. Among them, chemical sterilization refers to the sterilization of water with chemical disinfectants. Commonly used drinking water disinfectants at home and abroad are mainly halogens, especially chlorine disinfectants. Specifically, there are many types of chlorine-containing preparations, such as bleaching powder, calcium hypochlorite, chloramine, sodium dichloroisocyanurate, etc.; chlorine dioxide is called the fourth-generation disinfectant. It is the safest chemical agent recommended by WHO for treating drinking water and is an updated product of existing disinfectants; ozone is a strong oxidant with a broad-spectrum and high-efficiency bactericidal effect. It is mainly used for disinfection of drinking water, air disinfection and food preservation. Since the residues after chemical sterilization will affect the taste and smell of drinking water, it is not recommended to use it on refrigerator products. At present, the widely used physical disinfection of drinking water is heating, filtration, and ultraviolet rays. Boiling is the most commonly used method, which is simple, easy and reliable, but not suitable for refrigerator products; the filtering method is simple and effective. Although the refrigerator water filter can kill bacteria in the front-end water, the filtered water still has a long water pipe (generally 1.5-2 meters) to reach the user, and there are still bacterial safety issues in the subsequent water system; ultraviolet rays in the 240-280 nanometer band have the strongest bactericidal power, but ultraviolet germicidal LED lamps are expensive and require a larger space for additional structural design.

Compared with conventional chemical and physical methods, the use of antibacterial plastics has a long antibacterial effect, is economical and convenient. Therefore, in order to ensure the safety of water and ice cubes used by users, this can be achieved by inhibiting the bacterial growth of water system components, especially LLDPE plastic water pipes with the largest water contact area. However, the water valve configured in the ice-making system is placed in the refrigerator compressor compartment, and the pre-installed water pipes will also go through the foaming process of the refrigerator body insulation layer, with a temperature as high as 140 degrees, while the maximum heat resistance temperature of ordinary LLDPE materials is about 110°C. Therefore, the water pipes with antibacterial agents added have poor anti-aging properties and are prone to yellowing. In addition, antibacterial agents contain small molecules, which are easy to precipitate at high temperatures and form more accumulations at the die during the extrusion process.

Summary of the invention

In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is that the existing LLDPE plastic water pipes for refrigerators have the problems of poor antibacterial and temperature resistance, yellowing of the water pipes, and easy precipitation of antibacterial agents at the mouth mold. A modified antibacterial LLDPE material which is antibacterial, high temperature resistant and can effectively inhibit the precipitation of antibacterial agents, its preparation method, antibacterial water pipes and refrigerators are proposed.

In order to solve the technical problem, the technical solution adopted by the present invention is:

On one hand, the invention of this case provides a modified antibacterial LLDPE material, comprising: a modified LLDPE resin, a composite antibacterial masterbatch, and an antioxidant; maleic anhydride molecules are grafted onto the molecular chain of the modified LLDPE resin, and the modified LLDPE resin is filled with barium sulfate and calcium carbonate; the particle size of the barium sulfate is selected from any value in the range of 6250-8000 mesh, and the content of free barium ions is less than 10 mg/kg; the composite antibacterial masterbatch comprises a phosphate glass silver-loaded antibacterial agent, a lubricant, and a compatibilizer; the D98 of the phosphate glass silver-loaded antibacterial agent is less than 40 μm; and the compatibilizer is a silaneoxy-terminated polyethylene.

Preferably, the base material LLDPE of the modified LLDPE resin is linear low-density polyethylene; the particle size of the calcium carbonate is selected from any value in the range of 8000-12500 meshes, and the ratio of the barium sulfate to the calcium carbonate is 0.3-0.5:0.6-1.

Preferably, the lubricant in the composite antibacterial masterbatch is added during the granulation process of the composite antibacterial masterbatch, and is selected from silicone masterbatch with PE resin as a carrier, and the addition ratio is 2-3%.

Preferably, the antioxidant is a compound antioxidant, the main antioxidant is hindered phenols, and the auxiliary antioxidant is trisnonylphenyl phosphite or tris(2,4-di-tert-butylphenyl) phosphite.

Preferably, a coupling agent is further included, and the coupling agent is selected from at least one of anilinemethyltriethoxysilane, γ-(2,3-epoxypropoxy)-propyltrimethoxysilane, vinyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

Another aspect of the present invention provides a method for preparing the modified antibacterial LLDPE material listed in the above technical solution, including a composite antibacterial masterbatch preparation step, a modified LLDPE preparation step, and a modified antibacterial LLDPE material preparation step.

Preferably, the preparation step of the composite antibacterial masterbatch comprises: weighing 96-98 parts of phosphate glass silver-loaded powder, 2-3 parts of lubricant, and 1.5-2 parts of compatibilizer according to a weight ratio, first mixing the phosphate glass silver-loaded powder and the lubricant in a mixer at a low speed, then adding the compatibilizer, and mixing at a low speed at room temperature to obtain a uniformly dispersed composite antibacterial agent, and adding the composite antibacterial agent and the LLDPE resin to a twin-screw extruder according to mass fractions of 10-20 parts and 80-90 parts, respectively, the pre-melting temperature zone is 150-155°C, the first zone is 170-175°C, the second zone is 175-180°C, the third zone is 180-185°C, the fourth zone is 190-200°C, the discharge port temperature zone is 200-205°C, the screw speed is 280-320r/min, melt blending, extrusion, cooling, and granulation are performed to obtain the composite antibacterial masterbatch.

Preferably, the modified LLDPE preparation step comprises: weighing 80-85 parts of LLDPE-g-MAH and 15-30 parts of a mixture of barium sulfate and calcium carbonate according to a weight ratio, mixing them in a high-speed mixer at room temperature, then adding a composite antibacterial masterbatch, an antioxidant, and a coupling agent, mixing at 75-85°C for 60-120 minutes, and then adding it to a twin-screw extruder, with a pre-melting temperature zone of 150-160°C, a zone of 170-180°C, a zone of 175-185°C, a zone of 380-190°C, a zone of 4190-205°C, a discharge port temperature zone of 210-215°C, a screw speed of 300-350r/min, melt blending, extrusion, cooling, and granulation to obtain a heat-resistant modified antibacterial LLDPE material.

The present invention also provides a refrigerator, wherein the water pipe of the refrigerator is made of the modified antibacterial LLDPE material described in any of the above technical solutions. Preferably, the refrigerator is a refrigerator equipped with ice making and water drinking functions.

Preferably, the water pipe of the refrigerator is prepared by the following method: adding the modified antibacterial LLDPE material into a twin-screw extruder, the temperature of the twin-screw extruder is set to: pre-melting temperature zone 150-160°C, barrel zone 1 160-165°C, barrel zone 2 165-175°C, barrel zone 3 175-180°C, barrel zone 4 180-186°C, flange 185-188°C, head 185-190°C, mold 210-215°C, screw speed 30-35r/min, melt blending, extrusion, cooling, to obtain the water pipe.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention provides a modified antibacterial LLDPE material, which has the characteristics of antibacterial, high temperature resistance, and effective inhibition of the precipitation of antibacterial agents. Specifically:

In order to solve the problem that ordinary LLDPE water pipes cannot withstand high temperatures, a higher heat resistance temperature can be achieved by modifying LLDPE and adding a certain proportion of inorganic fillers (including barium sulfate and calcium carbonate);

The problem of yellowing of water pipes after adding antibacterial agents is caused by the fact that LLDPE material is sensitive to oxygen and its oxidation resistance is reduced after the addition of antibacterial agents. The use of composite antioxidants and barium sulfate at the same time improves the yellowing problem of antibacterial LLDPE materials.

Detailed ways

The technical scheme in the specific embodiment of the present invention is described in detail and completely below. Obviously, the described embodiment is only a part of the specific implementation of the overall technical scheme of the present invention, rather than all implementations. Based on the overall concept of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

On one hand, the invention of this case provides a modified antibacterial LLDPE material, including: modified LLDPE resin, composite antibacterial masterbatch, and antioxidant; maleic anhydride molecules are grafted on the molecular chain of the modified LLDPE resin, and the modified LLDPE resin is filled with barium sulfate and calcium carbonate; the particle size of the barium sulfate is selected from any value in 6250-8000 mesh, and the content of free barium ions is less than 10 mg/kg; the composite antibacterial masterbatch includes phosphate glass silver antibacterial agent, lubricant and compatibilizer; the D98 of the phosphate glass silver antibacterial agent is less than 40μm; the compatibilizer is silaneoxy-terminated polyethylene. By weight, the modified LLDPE resin is 90-93 parts, the composite antibacterial masterbatch is 5-10 parts, the antioxidant is 0.2-2 parts, and the coupling agent is 1-2 parts. The modified antibacterial LLDPE material has the characteristics of antibacterial, high temperature resistance, and can effectively inhibit the precipitation of antibacterial agents. Specifically: in view of the problem that ordinary LLDPE water pipes cannot withstand high temperatures, a certain proportion of inorganic fillers (including barium sulfate and calcium carbonate) are added to the modified LLDPE to achieve a higher heat-resistant temperature; in view of the yellowing problem of water pipes after adding antibacterial agents, the reason is that LLDPE materials are sensitive to oxygen, and the oxidation resistance is reduced after adding antibacterial agents. The use of composite antioxidants and barium sulfate can improve the yellowing problem of antibacterial LLDPE materials. It should be noted that antibacterial agents can be divided into three types: inorganic, organic and natural biological antibacterial agents. Since refrigerators with ice-making and drinking water functions are mainly exported to the European Union, the antibacterial agents used must meet the US EPA and EU BPR certifications. As parts in contact with water, water pipes also need to meet the US FDA and EU EU 10/2011 food grade regulations. Inorganic antibacterial agents added to materials in direct contact with water are the safest antibacterial agents. The present invention uses a silver ion antibacterial agent with a phosphate glass carrier, takes LLDPE as a matrix, and makes a composite silver ion antibacterial masterbatch to add to the LLDPE material. However, inorganic silver ion (Ag ⁺ ) antimicrobial agent has poor compatibility with LLDPE resin and is prone to agglomeration in the LLDPE matrix. Therefore, it is necessary to control the particle size of 98% of the phosphate glass silver carrier to be less than 40μm, and at the same time, maleic anhydride molecules are grafted on the LLDPE molecular chain to improve the compatibility of the polyolefin substrate and the antimicrobial masterbatch; (Ag ⁺ ) antimicrobial agent has poor antioxidant properties, and the antimicrobial LLDPE is prone to yellowing. 6250-8000 mesh barium sulfate can increase the whiteness of the antimicrobial LLDPE. The addition of antioxidants and barium sulfate can improve the yellowing problem of the antimicrobial LLDPE material. In order to further solve the compatibility problem of inorganic silver ion (Ag ⁺ ) antimicrobial agent with LLDPE resin, silaneoxy-terminated polyethylene is used as a compatibilizer to increase the compatibility of the inorganic carrier phosphate glass with the polyethylene matrix. Secondly, a polyethylene shell layer is formed on the surface of phosphate glass, which can also further control the sustained release of Ag ⁺ .

The above technical solution specifically defines that the composite antibacterial masterbatch includes a phosphate glass silver antibacterial agent, a lubricant and a compatibilizer. The D98 of the phosphate glass silver antibacterial agent is less than 40 μm. The reason is that phosphate glass is selected as the carrier of the Ag ⁺ antibacterial agent. The surface of phosphate glass is a porous structure with a large specific surface area, strong adsorption capacity, good chemical stability, and high temperature resistance. The loaded Ag ⁺ antibacterial agent produces a good sustained release effect, thereby making Ag ⁺ The antibacterial agent has the characteristics of resistance to ultraviolet light, high temperature and long-lasting antibacterial effect; the amount of silver ions dissolved in the glass carrier directly affects the antibacterial effect. If the dissolution amount is too small, the antibacterial effect cannot be achieved, but if the dissolution amount is too large, the antibacterial persistence is poor and the safety is not high. Therefore, in the production process, the raw material formula and production process must be continuously adjusted to adjust the concentration, quantity, speed, etc. of the placement and dissolution of silver ions, so as to ensure the antibacterial effect of the antibacterial agent while ensuring the safety during use; by limiting D98 < 40μm (98% of the phosphate glass silver-carrying particle size is less than 40μm) phosphate glass as a carrier of silver ions, the amount of silver ions dissolved in the glass carrier directly affects the antibacterial effect. If the dissolution amount is too small, the antibacterial effect cannot be achieved, but if the dissolution amount is too large, the antibacterial persistence is poor and the safety is not high. The chemical composition of phosphate glass is mainly composed of phosphoric acid, sodium oxide, calcium oxide, aluminum oxide and other oxides. By adjusting the ratio of sodium oxide and calcium oxide, the solubility of phosphate glass can be affected, the slow release of silver ions can be controlled, and the silver ions ingested by the human body in drinking water can be ensured to be within a safe range. In addition, adding lubricants during the granulation process of antibacterial masterbatch can effectively control the precipitation of small molecules and solve the problem that antibacterial agents are easily precipitated at the die. Specifically, the antibacterial masterbatch is a composite antibacterial masterbatch, and a plastic lubricant of a carrier-free polymer material is added during the granulation process. The plastic lubricant is resistant to high temperatures and does not precipitate. The polymer material lubricant wraps the metal surface layer and can also protect the screw from damage, which effectively solves the problem of die mouth accumulation and improves production efficiency.

Considering the compatibility of LLDPE and inorganic antimicrobial agents, the LLDPE resin is modified, and maleic anhydride molecules are grafted on the LLDPE molecular chain, so that the polyethylene end has the reactivity and strong polarity of maleic anhydride polar molecules, so it can improve the interfacial affinity between the polyolefin substrate and the glass, and achieve the purpose of compatibility between the substrate and the antimicrobial masterbatch. In addition, in order to improve the heat resistance temperature, the LLDPE resin is modified and compounded with barium sulfate and calcium carbonate. First, spherical barium sulfate produced by precipitation method is selected to improve the heat resistance of LLDPE, and the particle size selection range is 6250-8000 mesh. The larger the particle size of barium sulfate, the better the weather resistance and glossiness, but the worse the dispersibility. Through multiple experiments, it is proved that this particle size has the best dispersibility, and the barium ion content is controlled within 10ppm to ensure that it can meet the comprehensive migration test of food contact materials and the special migration test of heavy metals. Secondly, the particle size of light calcium carbonate is selected within the range of 8000-12500 mesh.

In a preferred embodiment, the base material LLDPE of the modified LLDPE resin is linear low-density polyethylene; the particle size of the calcium carbonate is selected from any value in the range of 8000-12500 mesh, and the ratio of the barium sulfate to the calcium carbonate is 0.3-0.5:0.6-1. Linear low-density polyethylene is different from general low-density polyethylene in structure because there is no long chain branching. It is a copolymer formed by high-pressure or low-pressure polymerization of ethylene and a small amount of high-grade α-olefins (such as butene-1, hexene-1, octene-1, tetramethylpentene-1, etc.) under the action of a catalyst, and the density is between 0.915-0.940 g/cm3. The LLDPE resin grades include but are not limited to the following commercial grades: Sinopec DFDA-7042, South Korea SK RG300U, Exxon LL1002KW.

In a preferred embodiment, the lubricant in the composite antibacterial masterbatch is added during the granulation process of the composite antibacterial masterbatch and is selected from silicone masterbatch with PE resin as a carrier, and the addition ratio is 2-3%.

In a preferred embodiment, the antioxidant is a compound antioxidant, the main antioxidant is a hindered phenol, and the auxiliary antioxidant is trisnonylphenyl phosphite or tris(2,4-di-tert-butylphenyl) phosphite. Among them, the hindered phenol antioxidant includes 2,6-tert-butyl-4-methylphenol or 1,3,5-trimethyl-2,4,6(3,5-2-tert-butyl-4-hydroxybenzyl)benzene. The compounding ratio of the main antioxidant to the auxiliary antioxidant is 1:1-1:4.

In a preferred embodiment, a coupling agent is also included, and the coupling agent is selected from at least one of aniline methyl triethoxysilane, γ-(2,3-epoxypropoxy)-propyl trimethoxysilane, vinyl triethoxysilane, and N-β-(aminoethyl)-γ-aminopropyl methyl dimethoxysilane. LLDPE is added with a coupling agent and a process to improve the adhesion and dispersibility of the filler and the matrix, and improve the mechanical properties of the material.

Another aspect of the present invention provides a method for preparing the modified antibacterial LLDPE material listed in the above technical solution, including a composite antibacterial masterbatch preparation step, a modified LLDPE preparation step, and a modified antibacterial LLDPE material preparation step.

In a preferred embodiment, the preparation step of the composite antibacterial masterbatch includes: weighing 96-98 parts of phosphate glass silver-loaded powder, 2-3 parts of lubricant, and 1.5-2 parts of compatibilizer according to a weight ratio, first mixing the phosphate glass silver-loaded powder and the lubricant in a mixer at a low speed, then adding the compatibilizer, and mixing at a low speed at room temperature to obtain a uniformly dispersed composite antibacterial agent, the composite antibacterial agent and the LLDPE resin are added to a twin-screw extruder according to mass fractions of 10-20 parts and 80-90 parts, respectively, the pre-melting temperature zone is 150-155°C, the first zone is 170-175°C, the second zone is 175-180°C, the third zone is 180-185°C, the fourth zone is 190-200°C, the discharge port temperature zone is 200-205°C, the screw speed is 280-320r/min, melt blending, extrusion, cooling, and granulation are performed to obtain the composite antibacterial masterbatch. The composite antibacterial masterbatch prepared by the above method is a composite of phosphate glass silver-carrying antibacterial agent, lubricant and compatibilizer, wherein phosphate glass is a carrier of silver ions, and the compatibilizer in the above composite antibacterial masterbatch is silaneoxy-terminated polyethylene, which increases the compatibility of the inorganic carrier phosphate glass with the polyethylene matrix. Secondly, a polyethylene shell layer is formed on the surface of phosphate glass, which can further control the sustained release of Ag+ and solve the problem of poor compatibility between the inorganic antibacterial agent and LLDPE. The addition ratio is 1.5-2%.

In a preferred embodiment, the modified LLDPE preparation step includes: weighing 80-85 parts of LLDPE-g-MAH and 15-30 parts of a mixture of barium sulfate and calcium carbonate according to a weight ratio, mixing them in a high-speed mixer at room temperature, then adding a composite antibacterial masterbatch, an antioxidant, and a coupling agent, mixing at 75-85°C for 60-120 minutes, and then adding it to a twin-screw extruder, with a pre-melting temperature zone of 150-160°C, a zone of 170-180°C, a zone of 175-185°C, a zone of 380-190°C, a zone of 4190-205°C, a discharge port temperature zone of 210-215°C, a screw speed of 300-350r/min, melt blending, extrusion, cooling, and granulation to obtain a heat-resistant modified antibacterial LLDPE material. Wherein, LLDPE-g-MAH is obtained by grafting linear low-density polyethylene (LLDPE) with maleic anhydride (MAH).

The present invention also provides a refrigerator, wherein the water pipe of the refrigerator is prepared from the modified antibacterial LLDPE material described in any of the above technical solutions. The water pipe of the refrigerator is prepared by the following method: adding the modified antibacterial LLDPE material into a twin-screw extruder, the temperature of the twin-screw extruder is set to: pre-melting temperature zone 150-160°C, barrel zone 1 160-165°C, barrel zone 2 165-175°C, barrel zone 3 175-180°C, barrel zone 4 180-186°C, flange 185-188°C, die 185-190°C, mold 210-215°C, screw speed 30-35r/min, melt blending, extrusion, cooling, and obtaining the water pipe.

In order to more clearly and in detail introduce the modified antibacterial LLDPE material, its preparation method, antibacterial water pipe and refrigerator provided in the embodiments of the present invention, they will be described in combination with specific embodiments below.

Example 1

Weigh the raw materials according to the following mass ratio:

65 parts of LLDPE-g-MAH resin, 5 parts of barium sulfate, 15 parts of calcium carbonate, 6 parts of composite antibacterial masterbatch, 2 parts of cold-resistant plasticizer, 0.5 parts of antioxidant, and 1 part of coupling agent.

The preparation process includes:

(1) Preparation of composite antibacterial masterbatch: 96 parts of antibacterial agent (phosphate glass silver powder), 2 parts of lubricant (silicone masterbatch), and 2 parts of compatibilizer (silanol-terminated polyethylene) were weighed according to the weight ratio, and the antibacterial agent and lubricant were first mixed at low speed in a mixer for 30-60 minutes, and then the compatibilizer was added and mixed at low speed for 30-60 minutes at room temperature to obtain a uniformly dispersed composite antibacterial agent. The composite antibacterial agent and LLDPE resin were added to a twin-screw extruder according to the mass fraction of 10 parts and 90 parts, respectively, with the pre-melting temperature zone of 152°C, the barrel zone 1 of 171°C, the barrel zone 2 of 178°C, the barrel zone 3 of 185°C, the barrel zone 4 of 190°C, and the outlet temperature zone of 200°C; the screw speed was 300r/min; melt blending, extrusion, cooling, and granulation were performed to obtain a composite antibacterial masterbatch.

(2) Preparation of modified LLDPE: 80-85 parts of LLDPE-g-MAH and 15-30 parts of filler (mixture of barium sulfate and calcium carbonate) were weighed according to the weight ratio and mixed in a high-speed mixer at room temperature for 60-90 minutes, and then the composite antibacterial masterbatch, antioxidant and coupling agent were added, mixed at 75-85°C for 60-120 minutes, and then added to a twin-screw extruder, with a pre-melting temperature zone of 155°C, a barrel zone 1 of 175°C, a barrel zone 2 of 170°C, a barrel zone 3 of 185°C, a barrel zone 4 of 195°C, and a discharge port temperature zone of 212°C; the screw speed was 305 r/min; melt blending, extrusion, cooling and granulation were carried out to obtain a heat-resistant antibacterial modified LLDPE material.

(3) Heat-resistant antibacterial LLDPE material is added into a twin-screw extruder, and the temperature of the twin-screw extruder is set as follows: pre-melt temperature zone 160°C, barrel zone 1 165°C, barrel zone 2 175°C, barrel zone 3 180°C, barrel zone 4 186°C, flange 188°C, head 190°C, mold 215°C; screw speed is 33 r/min; melt blending, extrusion, and cooling are performed to obtain a heat-resistant antibacterial LLDPE water pipe.

Comparative Example 1

Same as Example 1, except that no composite antibacterial masterbatch is used.

Comparative Example 2

The same as Example 1, except that no maleic anhydride molecules are grafted onto the molecular chains of the modified LLDPE resin.

Comparative Example 3

Same as Example 1, except that the particle size of the barium sulfate filled in the modified LLDPE resin is 6000 mesh.

Comparative Example 4

The same as Example 1, except that the particle size of the barium sulfate filled in the modified LLDPE resin is 8100 mesh.

Comparative Example 5

Same as Example 1, except that the content of free barium ions of barium sulfate filled in the modified LLDPE resin is 15 mg/kg.

Comparative Example 6

Same as Example 1, except that the D98 of the phosphate glass silver-loaded antibacterial agent in the composite antibacterial masterbatch is greater than 40 μm.

Comparative Example 7

Same as Example 1, except that the compatibilizer is polyethylene.

Performance Testing

The materials obtained in Example 1 and Comparative Examples 1-7 were made into sheet samples, and the antibacterial test and Vicat softening temperature test according to ISO22196 standard were carried out. The test results are shown in Tables 1-4.

Table 1 Test results

Test items Comparative Example 1 Comparative Example 2 Example 1 Antibacterial test: Staphylococcus aureus, Escherichia coli No antibacterial function 95%, 94% Greater than 99.9% Vicat softening temperature℃ 105 118 120

Table 2 Test results

Test items Comparative Example 3 Comparative Example 4 Example 1 Color difference (ΔL) 0.3 0.6 0.5

Table 3 Test results

Test items Comparative Example 5 Example 1 Specific migration of heavy metals (Ba) 1.05ppm Less than 1ppm

Table 4 Test results

Claims (10)

1. A modified antibacterial LLDPE material, comprising: modified LLDPE resin, composite antibacterial master batch and antioxidant;

the molecular chain of the modified LLDPE resin is grafted with maleic anhydride molecules, and the modified LLDPE resin is filled with barium sulfate and calcium carbonate; the particle size of the barium sulfate is selected from any value of 6250-8000 meshes, and the content of free barium ions is lower than 10mg/kg;

The composite antibacterial master batch comprises a phosphate glass silver-loaded antibacterial agent, a lubricant and a compatibilizer; the D98 of the phosphate glass silver-loaded antibacterial agent is less than 40 mu m; the compatibilizer is a siloxy terminated polyethylene.

2. The modified antibacterial LLDPE material of claim 1, wherein said base LLDPE of said modified LLDPE resin is a linear low density polyethylene; the particle size of the calcium carbonate is any value selected from 8000-12500 meshes, and the ratio of the barium sulfate to the calcium carbonate is 0.3-0.5:0.6-1.

3. A modified antibacterial LLDPE material according to claim 1, wherein said lubricant in said composite antibacterial master batch is added during granulation of said composite antibacterial master batch, selected from silicone master batches with PE resin as carrier, in an addition ratio of 2-3%.

4. The modified antibacterial LLDPE material of claim 1, wherein said antioxidant is a compounded antioxidant, wherein said primary antioxidant is a hindered phenol, and wherein said secondary antioxidant is trisnonylphenyl phosphite or tris (2, 4-di-t-butylphenyl) phosphite.

5. A modified antibacterial LLDPE material according to claim 1, further comprising a coupling agent selected from at least one of the group consisting of phenylmethyltriethoxysilane, γ - (2, 3-glycidoxy) -propyltrimethoxysilane, vinyltriethoxysilane, N- β - (aminoethyl) - γ -aminopropylmethyldimethoxysilane.

6. The method of producing a modified antibacterial LLDPE material according to any one of claims 1 to 5, comprising a composite antibacterial master batch production step, a modified LLDPE production step, and a modified antibacterial LLDPE material production step.

7. The method of preparing a modified antibacterial LLDPE material according to claim 6, wherein said composite antibacterial masterbatch preparing step comprises: weighing 96-98 parts of phosphate glass silver-carrying powder, 2-3 parts of lubricant and 1.5-2 parts of compatibilizer according to weight ratio, firstly mixing the phosphate glass silver-carrying powder and the lubricant in a stirrer at low speed, then adding the compatibilizer, mixing at low speed at normal temperature to obtain uniformly dispersed composite antibacterial agent, respectively adding 10-20 parts by mass and 80-90 parts by mass of the composite antibacterial agent and LLDPE resin into a double-screw extruder, wherein the pre-melting temperature is 150-155 ℃, the first region is 170-175 ℃, the second region is 175-180 ℃, the third region is 180-185 ℃, the fourth region is 190-200 ℃, the temperature of a discharge hole is 200-205 ℃, the screw speed is 280-320r/min, and carrying out melt blending, extrusion, cooling and granulation to obtain the composite antibacterial master batch.

8. The method of preparing a modified antibacterial LLDPE material according to claim 6, wherein said modified LLDPE preparation step comprises: weighing 80-85 parts of LLDPE-g-MAH and 15-30 parts of barium sulfate and calcium carbonate mixture according to weight proportion, mixing at normal temperature in a high-speed mixer, adding the composite antibacterial master batch, the antioxidant and the coupling agent, mixing for 60-120min at 75-85 ℃, adding the mixture into a double-screw extruder, pre-melting at 150-160 ℃, 170-180 ℃, 175-185 ℃ in one zone, 180-190 ℃ in three zones, 190-205 ℃ in four zones, 210-215 ℃ in a discharge port, and 300-350r/min in screw speed, and carrying out melt blending, extrusion, cooling and granulation to obtain the modified antibacterial LLDPE material with heat resistance.

9. A refrigerator, characterized in that the water pipe of said refrigerator is prepared from a modified antibacterial LLDPE material according to any one of claims 1-5.

10. The refrigerator of claim 9, wherein the water pipe of the refrigerator is prepared by the following method: the modified antibacterial LLDPE material is added to a twin screw extruder, the temperature of the twin screw extruder is set as follows: the water pipe is obtained by carrying out melt blending, extrusion and cooling on a pre-melting temperature zone of 150-160 ℃, a first charging barrel zone of 160-165 ℃, a second charging barrel zone of 165-175 ℃, a third charging barrel zone of 175-180 ℃, a fourth charging barrel zone of 180-186 ℃, a flange of 185-188 ℃, a machine head of 185-190 ℃, a die of 210-215 ℃ and a screw rotating speed of 30-35 r/min.