A kind of stretch film for puncture-resistant machine and preparation method thereof

Abstract

The present application relates to the technical field of stretch film, specifically disclosing a puncture-resistant stretch film for a machine and its preparation method. A puncture-resistant stretch film for a machine comprises a mixture and a tackifier; the mixture comprises 120-130 parts of metallocene low-density polyethylene A, 120-130 parts of metallocene low-density polyethylene B, 4-7 parts of polyolefin elastomer, and 240-280 parts of linear low-density polyethylene. The preparation method comprises: mixing metallocene low-density polyethylene A, metallocene low-density polyethylene B, polyolefin elastomer, and linear low-density polyethylene to obtain a mixture; plasticizing and mixing the mixture and the tackifier, casting, cooling, and winding to obtain a puncture-resistant stretch film for a machine; the plasticizing temperature is 200-260°C. The puncture-resistant stretch film for a machine of the present application can effectively absorb and disperse puncture force, is not easy to break during stretching, reduces damage to the stretch film by sharp objects, and has excellent tensile strength and puncture resistance.

Description

Technical Field

[0001] The present application relates to the technical field of stretch films, and more specifically, to a stretch film for puncture-resistant machines and a preparation method thereof. Background Art

[0002] Machine stretch film is a plastic film used for mechanical packaging. It is generally made of linear low-density polyethylene as the main raw material and is made by extrusion blow molding or cast film process.

[0003] Machine stretch film has excellent tensile strength and toughness and can be used to package various types of goods, effectively preventing them from being damaged during transportation, handling, and storage.

[0004] However, if the goods have sharp edges, such as the edges of metal products, burrs on wood, etc., during transportation, these sharp parts will come into direct contact with the stretch film. As the vehicle bumps and shakes, they will continue to exert pressure on the stretch film, making it very easy to puncture the stretch film. Summary of the Invention

[0005] In order to improve the puncture resistance of a stretch film, the present application provides a puncture-resistant stretch film for a machine and a preparation method thereof.

[0006] In a first aspect, the present application provides a puncture-resistant stretch film for a machine and a preparation method thereof, which adopts the following technical solutions:

[0007] A puncture-resistant stretch film for machines, comprising the following components in parts by weight:

[0008] 100 parts of mixed material;

[0009] 40-50 parts of tackifier;

[0010] The mixture comprises the following components in parts by weight:

[0011] 120-130 parts of metallocene low-density polyethylene A;

[0012] 120-130 parts of metallocene low-density polyethylene B;

[0013] 4-7 parts of polyolefin elastomer;

[0014] 240-280 parts of linear low-density polyethylene;

[0015] The metallocene low-density polyethylene A has a melt flow rate of 3.0 to 3.8 g / 10 min at 190° C. / 2.16 kg;

[0016] The metallocene low-density polyethylene B has a melt flow rate of 1.0 to 2.0 g / 10 min at 190° C. / 2.16 kg.

[0017] By adopting this technical solution, on the one hand, the metallocene low-density polyethylene (MDPE) A and B with specific melt flow rates are used as the blend. Due to their excellent tensile strength and puncture resistance, the stretch film is less likely to break during stretching, making the resulting stretch film more durable and resilient. On the other hand, the MDPE B and polyolefin elastomer with specific melt flow rates not only possess excellent flexibility and elasticity, but also excellent processability. When wrapped, the resulting stretch film can be tightly wrapped around the surface of the goods, forming a "buffer layer" structure that effectively absorbs and disperses puncture force, thereby improving the film's puncture resistance and reducing damage from sharp objects.

[0018] Preferably, the density of the metallocene low-density polyethylene A is 0.918 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 3.5g / 10min.

[0019] By adopting the above technical solution, the metallocene low-density polyethylene A has moderate fluidity and is easy to extrude and shape during the processing. The final stretch film can not only withstand greater tension without breaking, but also tightly wrap the goods during the packaging process, effectively protecting the goods from external impact and damage from sharp objects, and has high tensile strength and puncture resistance.

[0020] Preferably, the density of the metallocene low-density polyethylene B is 0.913 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 2.0g / 10min.

[0021] By adopting the above technical solution, since the above-mentioned metallocene low-density polyethylene B has strong intermolecular chain interaction and high flexibility, the stretch film prepared therefrom has high tensile strength and puncture resistance, can withstand large tensile forces, and effectively resist puncture from sharp objects, which is beneficial to improving the safety of goods during packaging and transportation.

[0022] Preferably, the density of the polyolefin elastomer is 0.862 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 0.8~1.5g / 10min.

[0023] Preferably, the density of the polyolefin elastomer is 0.862 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.4g / 10min.

[0024] By adopting the above technical solution, the above-mentioned polyolefin elastomer has excellent elasticity, flexibility and compatibility. When mixed with metallocene low-density polyethylene B, the two raw materials have good processing fluidity. The resulting stretch film can be easily adhered to the surface of an object, so that the stretch film can be stretched to a large extent without breaking, effectively resisting puncture from sharp objects, and has excellent tensile strength and puncture resistance.

[0025] Preferably, the density of the linear low-density polyethylene is 0.916-0.920 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.0~2.3g / 10min.

[0026] By adopting this technical solution, the linear structure of the linear low-density polyethylene (LLDPE) results in a more regular molecular chain arrangement, stronger intermolecular forces, and superior tensile strength and puncture resistance. When subjected to a puncture force, the wrap can withstand a certain amount of external force without easily pulling apart or breaking.

[0027] Preferably, the thickness of the puncture-resistant stretch film is 30 to 40 μm.

[0028] By adopting the above technical solution, the puncture-resistant machine stretch film prepared by mixing the mixture and the thickener in this application not only has high tensile strength and puncture resistance, but also has a thinner thickness and better transparency, which is convenient for quick identification of goods.

[0029] In a second aspect, the present application provides a method for preparing a puncture-resistant stretch film for a machine, which adopts the following technical solution: A method for preparing a puncture-resistant stretch film for a machine, comprising the following steps:

[0030] S1: mixing metallocene low-density polyethylene A, metallocene low-density polyethylene B, polyolefin elastomer and linear low-density polyethylene to obtain a mixture;

[0031] S2: plasticizing and mixing the mixture and the tackifier, casting, cooling, and winding to obtain a puncture-resistant stretch film;

[0032] The plasticizing temperature is 200-260°C.

[0033] By adopting the above technical solution, the mixed material and tackifier can be fully plasticized at the above temperature to form a uniform and fluid melt. The melt is then cast into a stretch film with excellent tensile strength and puncture resistance.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Since the present application uses metallocene low-density polyethylene A and metallocene low-density polyethylene B as the raw materials for the mixture, the mixture is endowed with excellent processing properties, and the prepared stretch film has high tensile strength and puncture resistance;

[0036] 2. In this application, a polyolefin elastomer with a melt flow rate in the range of 0.8 to 1.5 g / 10 min is preferably used as the raw material of the mixture, so that the mixture has excellent adhesion and elasticity, and effectively improves the tensile strength and puncture resistance of the stretch film;

[0037] 3. The method of the present application controls the plasticizing temperature and extrusion temperature of the mixture and the tackifier so that each raw material can be fully plasticized and have high fluidity, which is beneficial to improving the tensile strength and puncture resistance of the stretch film. DETAILED DESCRIPTION

[0038] The present application is further described in detail below with reference to the embodiments.

[0039] Performance testing

[0040] The tensile strength, elongation at break and puncture resistance tests were performed on the puncture-resistant machine stretch film prepared in the examples of the present application and the machine stretch film prepared in the comparative example. The test methods are as follows:

[0041] Tensile strength: Refer to GB / T1040.3 test;

[0042] Elongation at break and puncture resistance: refer to BB / T0024-2004 test.

[0043] Example

[0044] Example 1

[0045] A puncture-resistant stretch film for machine use, the components and their corresponding weights (kg) are shown in the following table.

[0046]

[0047] The method for preparing the puncture-resistant stretch film for machine use comprises the following steps:

[0048] S1: Metallocene low-density polyethylene A, metallocene low-density polyethylene B, polyolefin elastomer, and linear low-density polyethylene are equally divided and added to screw extruder B and screw extruder C, respectively, for stirring and mixing to obtain a mixture;

[0049] The stirring speed of screw extruder B was 48.2 r / min, and the stirring speed of screw extruder C was 56 r / min.

[0050] S2:

[0051] S21: First, half the weight of the tackifier is added to the screw extruder A for plasticization and melting, then extruded to the distributor, and finally extruded to the left die to obtain the tackifier melt on the left;

[0052] First, add the remaining tackifier into the screw extruder D for plasticization and melting, then extrude it into the distributor, and finally extrude it into the right die head to obtain the tackifier melt on the right side;

[0053] Screw extruders B and C plasticize and melt the mixed materials respectively, and then extrude them together into a distributor and then into an intermediate die to obtain a mixed material melt;

[0054] S22: The left tackifier, the left tackifier, and the right tackifier melts pass through corresponding die heads and enter the casting machine at the same time for mixing, and then are cast into a film. The film is cooled and shaped, and wound to obtain a puncture-resistant stretch film.

[0055] In the embodiment of the present application, the extrusion speed of the screw extruder A for plasticizing and melting is 59.8 r / min, and the extrusion temperature is divided into five zones, zone I is 190°C, zone II is 200°C, zone III is 225°C, zone IV is 245°C, and zone V is 260°C;

[0056] The screw extruder B has an extrusion speed of 56 r / min for plasticizing and melting, and the extrusion temperature is divided into five zones: zone I is 190°C, zone II is 200°C, zone III is 225°C, zone IV is 240°C, and zone V is 240°C.

[0057] The screw extruder C has an extrusion speed of 56 r / min for plasticizing and melting, and the extrusion temperature is divided into five zones: zone I is 190°C, zone II is 200°C, zone III is 225°C, zone IV is 240°C, and zone V is 240°C.

[0058] The extrusion speed of screw extruder D for plasticizing and melting is 59.8 r / min, and the extrusion temperature is divided into five zones, zone I is 190°C, zone II is 200°C, zone III is 225°C, zone IV is 240°C, and zone V is 240°C.

[0059] The temperature of the distributors was 250°C.

[0060] The temperature of the middle die was 250°C; the temperature of the left die and the right die were both 250°C.

[0061] The line speed of the casting machine was 145 m / min.

[0062] Examples 2-3

[0063] A puncture-resistant stretch film for machine use, which is different from Example 1 in that the components and their corresponding weights (kg) are shown in the following table.

[0064]

[0065] The tensile strength, elongation at break and puncture resistance tests were performed on the puncture-resistant stretch films prepared in Examples 1 to 3 of the present application. The test results are shown in the following table.

[0066]

[0067] By analyzing the data in the above table, it can be seen that the puncture-resistant stretch film prepared in Examples 1 to 3 has a transverse tensile strength of up to 60-70 MPa, a longitudinal tensile strength of up to 61-71 MPa, a transverse elongation at break of up to 715-830 MPa, a longitudinal elongation at break of up to 610-715 MPa, a puncture resistance of up to 25-33 N, and an elongation of up to 85-99 mm. This shows that the puncture-resistant stretch film prepared in Examples 1 to 3 of the present application has excellent tensile strength, elongation at break, and puncture resistance, is not easy to break during the stretching process, and can reduce damage to the stretch film by sharp objects.

[0068] At the same time, compared with Examples 2 and 3, Example 1 has higher tensile strength, puncture resistance and elongation. This shows that the inclusion of 50% metallocene low-density polyethylene in the mixture of the total raw materials for preparing the puncture-resistant stretch film of the present application can improve the tensile strength and puncture resistance of the puncture-resistant stretch film.

[0069] Example 4

[0070] A puncture-resistant stretch film for machine use, which is different from Example 1 in that the metallocene low-density polyethylene A is made of Japanese Primen SP3530 with a density of 0.903 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 3.8g / 10min;

[0071] Metallocene low-density polyethylene B, brand Exxon 2010ME, density 0.920 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.0g / 10min.

[0072] The tensile strength, elongation at break and puncture resistance tests were performed on the puncture-resistant stretch films prepared in Examples 1 and 4 of the present application. The test results are shown in the following table.

[0073]

[0074] By analyzing the data in the above table, it can be seen that the puncture-resistant stretch film prepared in Examples 1 and 4 has a transverse tensile strength of up to 61-70 MPa, a longitudinal tensile strength of up to 62-71 MPa, a transverse elongation at break of up to 733-820 MPa, a longitudinal elongation at break of up to 621-700 MPa, a puncture resistance of up to 27-35 N, and an elongation of up to 89-99 mm. This shows that in the total raw materials for the preparation of the puncture-resistant stretch film of the present application, when the melt flow rate of metallocene low-density polyethylene A at 190°C / 2.16 kg is 3.0-3.8 g / 10 min; the melt flow rate of metallocene low-density polyethylene B at 190°C / 2.16 kg is 1.0-2.0 g / 10 min, the prepared puncture-resistant stretch film has both excellent tensile strength and puncture resistance.

[0075] Example 5

[0076] A puncture-resistant stretch film for a machine, which is different from Example 1 in that the polyolefin elastomer is Dow TM ENGAGE TM 8180, density 0.870g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 0.8g / 10min.

[0077] Example 6

[0078] A puncture-resistant stretch film for a machine, which is different from Example 1 in that the polyolefin elastomer is Dow TM ENGAGE TM 8440, density is 0.862g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.5g / 10min.

[0079] The tensile strength, elongation at break and puncture resistance tests were performed on the puncture-resistant stretch films prepared in Examples 1, 5 and 6 of the present application. The test results are shown in the following table.

[0080]

[0081] By analyzing the data in the above table, it can be seen that the puncture-resistant stretch film prepared in Examples 1, 5, and 6 has a transverse tensile strength of up to 64-70 MPa, a longitudinal tensile strength of up to 65-71 MPa, a transverse elongation at break of up to 785-820 MPa, a longitudinal elongation at break of up to 665-700 MPa, a puncture-resistant rupture force of up to 31-35 N, and an elongation of up to 93-99 mm. This shows that in the total raw materials for the preparation of the puncture-resistant stretch film of the present application, when the density of the polyolefin elastomer is 0.862 g / cm 3When the melt flow rate at 190℃ / 2.16kg is 0.8-1.5g / 10min, the prepared puncture-resistant stretch film has excellent tensile strength, elongation at break and puncture resistance.

[0082] At the same time, compared with Examples 5 and 6, Example 1 has higher tensile strength, elongation at break, puncture resistance and elongation. The reason for this may be that the polyolefin elastomer in Example 1 has excellent elasticity, flexibility and compatibility, high processing fluidity, and excellent processing performance of each raw material, thereby improving the tensile strength and puncture resistance of the stretch film for the puncture-resistant machine.

[0083] Example 7

[0084] A puncture-resistant stretch film for machine use, which is different from Example 1 in that the linear low-density polyethylene, brand Dow Chemical 2045G, has a density of 0.920 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.0g / 10min.

[0085] The tensile strength, elongation at break and puncture resistance tests were performed on the puncture-resistant stretch films prepared in Examples 1 and 7 of the present application. The test results are shown in the following table.

[0086]

[0087]

[0088] By analyzing the data in the above table, it can be seen that the puncture-resistant stretch film prepared in Examples 1 and 7 has a transverse tensile strength of up to 62-70 MPa, a longitudinal tensile strength of up to 63-71 MPa, a transverse elongation at break of up to 752-820 MPa, a longitudinal elongation at break of up to 640-700 MPa, a puncture resistance of up to 29-35 N, and an elongation of up to 91-99 mm. This shows that in the total raw materials for the preparation of the puncture-resistant stretch film of the present application, when the density of the linear low-density polyethylene is 0.916-0.920 g / cm 3 When the melt flow rate at 190℃ / 2.16kg is 1.0-2.3g / 10min, the prepared puncture-resistant stretch film has excellent tensile strength, elongation at break and puncture resistance.

[0089] At the same time, referring to GB / T6672-2001 "Mechanical measurement method for the determination of thickness of plastic film and sheeting", the thickness of the puncture-resistant machine stretch film prepared in Examples 1 to 7 of the present application was tested. The test results showed that the puncture-resistant machine stretch film prepared in Examples 1 to 7 of the present application had a thickness in the range of 30 to 40 μm.

[0090] Comparative Example

[0091] Comparative Example 1

[0092] A stretch film for machine use, which is different from Example 1 in that the metallocene low-density polyethylene A, brand 1520sp, density 0.913g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 2.0g / 10min;

[0093] Metallocene low-density polyethylene B, brand ExxonMobil 3518CB, density 0.918 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 3.5g / 10min.

[0094] Comparative Example 2

[0095] A stretch film for machine use, which is different from Example 1 in that the metallocene low-density polyethylene A, brand ExxonMobil TM Exceed TM 3527FB, density 0.917g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 5.0g / 10min;

[0096] Metallocene low-density polyethylene B, brand mPE-LD F184FS, density 0.919 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 0.8g / 10min.

[0097] The tensile strength, elongation at break and puncture resistance tests were performed on the machine stretch films prepared in Comparative Examples 1 and 2 of the present application. The test results are shown in the following table.

[0098]

[0099]

[0100] By analyzing the data in the above table, it can be seen that compared with Comparative Examples 1 and 2, the transverse tensile strength of Example 1 is relatively increased by 27.27~40.00%, the longitudinal tensile strength is relatively increased by 31.48~44.90%, the transverse elongation at break is relatively increased by 20.59~22.75%, the longitudinal elongation at break is relatively increased by 22.81~25.00%, the puncture resistance is relatively increased by 66.67~75.00%, and the elongation is relatively increased by 22.22~23.75%.

[0101] This shows that in the total raw materials for preparing the puncture-resistant stretch film of the present application, when the melt flow rate of metallocene low-density polyethylene A at 190°C / 2.16kg is 3.0-3.8g / 10min; when the melt flow rate of metallocene low-density polyethylene B at 190°C / 2.16kg is 1.0-2.0g / 10min, the tensile strength, elongation at break and puncture resistance of the puncture-resistant stretch film can be improved.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A stretch film for puncture-resistant machines, characterized in that: The composition comprises the following components in parts by weight: 100 parts of mixed material; 40-50 parts of tackifier; The mixture comprises the following components in parts by weight: 120-130 parts of metallocene low-density polyethylene A; 120-130 parts of metallocene low-density polyethylene B; 4-7 parts of polyolefin elastomer; 240-280 parts of linear low-density polyethylene; The metallocene low-density polyethylene A has a melt flow rate of 3.0 to 3.8 g / 10 min at 190° C. / 2.16 kg; The metallocene low-density polyethylene B has a melt flow rate of 1.0 to 2.0 g / 10 min at 190° C. / 2.16 kg; The tackifier is brand Zeheng ZH101; The polyolefin elastomer has a density of 0.862 g / cm³ and a melt flow rate of 0.8 to 1.5 g / 10 min at 190° C. / 2.16 kg.

2. The puncture-resistant stretch film for machines according to claim 1, characterized in that: The metallocene low-density polyethylene A has a density of 0.918 g / cm³ and a melt flow rate of 3.5 g / 10 min at 190° C. / 2.16 kg.

3. The puncture-resistant stretch film for machines according to claim 2, wherein: The metallocene low-density polyethylene B has a density of 0.913 g / cm³ and a melt flow rate of 2.0 g / 10 min at 190° C. / 2.16 kg.

4. The puncture-resistant stretch film for machines according to claim 1, characterized in that: The polyolefin elastomer has a density of 0.862 g / cm³ and a melt flow rate of 1.4 g / 10 min at 190° C. / 2.16 kg.

5. The puncture-resistant stretch film for machines according to claim 1, characterized in that: The linear low-density polyethylene has a density of 0.916 to 0.920 g / cm³ and a melt flow rate of 1.0 to 2.3 g / 10 min at 190° C. / 2.16 kg.

6. The puncture-resistant stretch film for machines according to claim 1, characterized in that: The thickness of the puncture-resistant stretch film for machines is 30 to 40 μm.

7. The method for preparing the puncture-resistant stretch film for machine use according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: mixing metallocene low-density polyethylene A, metallocene low-density polyethylene B, polyolefin elastomer and linear low-density polyethylene to obtain a mixture; S2: plasticizing and mixing the mixture and the tackifier, casting, cooling, and winding to obtain a puncture-resistant stretch film; The plasticizing temperature is 200-260°C.

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