An ultra-thin single-layer FFS film and a preparation method thereof

Abstract

The present invention belongs to the technical field of packaging films, and more specifically, it relates to an ultra-thin single-layer FFS film and a preparation method thereof. The ultra-thin single-layer FFS film is obtained by calendering a modified PE sheet; the preparation steps of the modified PE sheet are as follows: S1, first melt one or more of m-LLDPE, HDPE and MDPE, and then spray it out, and after cooling and stretching to form filament fibers, lay it into a spunbond filament fiber web; S2, then fill the LDPE composite modified glue into the spunbond filament fiber web obtained in S1, and then after it is cured, hot press and shape it to obtain a modified PE sheet; the LDPE composite modified glue is obtained by melting one or more of LDPE composite acrylic resin and EVA resin. The present application takes into account both the ease of processing and the mechanical properties of the finished film through the above-mentioned modified PE sheet.

Description

Technical Field

[0001] The invention belongs to the technical field of packaging films, and more specifically, relates to an ultra-thin single-layer FFS film and a preparation method thereof. Background Art

[0002] FFS (Form-Fill-Seal) packaging film refers to a new type of co-extruded heavy-duty packaging material that can achieve one-time automatic forming (Form), automatic opening filling (Fill) and automatic bag mouth heating sealing (Seal) multiple processes at high speed and continuously, and therefore has extremely high application value and research and development potential.

[0003] The FFS packaging film in the related art is made of one or more of LDPE, m-LLDPE, HDPE and MDPE, compounded with a small amount of processing aids, and has a three-layer or more film structure, and the thickness is generally 0.14-0.18mm. If the film thickness is less than 0.14mm, the processing difficulty will be significantly increased;

[0004] The difficulty of processing is mainly reflected in the following aspects:

[0005] 1) The requirements for the performance of the raw materials of the inner and outer layers have been significantly improved. The current formulations of LDPE, m-LLDPE, HDPE and MDPE will result in the inability to take into account the performance of heavy packaging films, especially the tensile strength of FFS films, which is prone to various accidents such as package rupture;

[0006] 2) The production process of three-layer or more heavy packaging films is complicated and requires multiple extruders, resulting in high equipment and operating costs. In addition, the addition of rigid materials such as LLDPE, m-LLDPE and HDPE further increases the difficulty of processing, making it difficult to be widely used in production.

[0007] In summary, there is an urgent need to provide an ultra-thin single-layer FFS membrane with excellent performance and a preparation method thereof that is easy to process and operate. Summary of the invention

[0008] In order to achieve the compatibility of the mechanical properties and processability of the ultra-thin single-layer film, the present application specifically provides an ultra-thin single-layer FFS film with excellent performance and a preparation method thereof that is easy to process and operate.

[0009] In the first aspect, the present application provides an ultra-thin single-layer FFS film, and the specific scheme is as follows:

[0010] An ultra-thin single-layer FFS film is made by calendering a modified PE sheet;

[0011] The preparation steps of the modified PE sheet are as follows:

[0012] S1, firstly melt one or more of m-LLDPE, HDPE and MDPE, then spray it out, cool and stretch it to form filament fibers, and then lay it into a spunbond filament fiber web;

[0013] S2, filling the LDPE composite modified rubber into the spunbonded filament fiber web obtained in S1, and then heat-pressing and shaping it after curing, so as to obtain a modified PE sheet;

[0014] The LDPE composite modified rubber is prepared by melting one or more of LDPE composite acrylic resin and EVA resin.

[0015] By adopting the above technical solution, the spunbond filament fiber web made by spinning one or more materials of m-LLDPE, HDPE and MDPE not only has both strength and toughness through its cross-linked network structure, but also has its own processing ease significantly improved;

[0016] In the subsequent process of combining with LDPE composite modified rubber, a composite structure with rigid material as the network veins and flexible material as the main filler can be formed. After hot pressing and shaping, the composite structure takes into account the processing ease and material mechanical properties to a great extent, thereby reducing equipment requirements. Using a low-cost calendering method, ultra-thin FFS film with a film thickness of less than 0.14mm can be produced.

[0017] It should be noted that the co-extrusion equipment for producing multi-layer heavy-duty packaging films takes up a large space and requires high equipment control precision. A multi-layer heavy-duty packaging film production equipment with good performance costs more than 5 million yuan, and imported equipment even costs more than 10 million yuan. Therefore, the overall investment is very large and the cost recovery time is long. Therefore, the above-mentioned calendered ultra-thin single-layer FFS film has broad market prospects.

[0018] Preferably, the raw materials for preparing the spunbond filament fiber web consist of m-LLDPE and MDPE in a weight ratio of 1:(0.5-0.8).

[0019] Preferably, the usage ratio of the spunbond filament web to the LDPE composite modified rubber is 1:(0.8-1.2), and the textile surface density is 200-500g / m 2 .

[0020] By adopting the above technical solution, the spunbonded filament fiber web of the material and textile surface density, in addition to effectively taking into account the strength and toughness through its own mesh structure, is more firmly bonded with the LDPE composite modified rubber and can provide sufficient bonding sites;

[0021] In addition, the composite structure obtained by the above-mentioned method of combining non-woven fabrics and fillings with rigid materials as the mesh veins and flexible materials as the main fillers has the characteristics of taking into account both processability and material mechanical properties compared to the direct mixing method, and can be produced by calendering.

[0022] Preferably, the LDPE composite modified rubber is composed of the following components in parts by weight: 80-120 parts of LDPE, 0-40 parts of polypropylene resin and 40-80 parts of EVA resin.

[0023] Preferably, the VA content of the EVA resin is 5-10%.

[0024] By adopting the above technical solution, the LDPE composite modified adhesive with the above component ratio effectively combines the permeability and adhesion, and through the firm combination of the two, forms a composite structure with rigid material as the network vein and easy material as the main filler.

[0025] Preferably, the method of filling the LDPE composite modified glue into the spunbonded filament fiber web in S2 is a glue spraying method; the specific parameter conditions are: the glue spraying amount is 160-600g / m 2 .

[0026] By adopting the above technical scheme, the above spraying treatment method can more effectively realize the modification of PE premix, and the LDPE composite modified glue will act on the spunbond filament fiber web through gravity, prompting it to further entangle and combine, thereby ensuring the formation of a composite structure with rigid material as the web vein and flexible material as the main filler, thereby achieving a balance between material processing ease and mechanical properties.

[0027] In a second aspect, the present application provides a method for preparing an ultra-thin single-layer FFS film, comprising the following preparation steps:

[0028] A1. Calendering: First, the obtained modified PE sheet is calendered into a film blank by multi-stage calendering;

[0029] A2. Cooling and shaping: Then the film blank is cooled to room temperature through step-by-step cooling;

[0030] A3. Rewinding and slitting: After the film blank is peeled off from the roller surface, the film blank is slit and rewound to obtain the ultra-thin single-layer FFS film product.

[0031] By adopting the above technical solution, the processing conditions and difficulty are significantly reduced, and the calender can replace multiple extruders. At the same time, the quality of the finished product is better. Due to the characteristics of modified PE, it also eliminates the step of mixing raw materials, so it has extremely high application and industrial value.

[0032] Preferably, the specific steps of the multi-stage calendering in A1 are as follows:

[0033] 1) Primary calendering: roller temperature 105-115°C, calendering roller rotation speed 20-30m / min;

[0034] 2) Secondary calendering: roller temperature 100-110°C, calendering roller rotation speed 10-20m / min;

[0035] 3) Three-stage calendering: roller temperature 90-100℃, calendering roller rotation speed 10-15m / min.

[0036] By adopting the above technical solution, this application is adjusted to a step-by-step cooling type based on the characteristics of the PE sheet composite structure. This method can make full use of the waste heat of the previous calendering, combined with a specific calendering roller speed, without the need for additional heating and temperature control. In addition, it can also cooperate with the step-by-step cooling process in A2 to further enhance the stability of product thickness and size.

[0037] Preferably, the specific steps of step-by-step cooling in A2 are as follows:

[0038] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 50-80°C;

[0039] 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 30-50℃;

[0040] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0041] By adopting the above technical solution, the multi-stage cooling method can effectively avoid the thickness or size fluctuation of the product due to inconsistent shrinkage force compared to direct cooling. Visually, the thickness of the finished film is uniform, and there is no deformation, warping and other undesirable conditions.

[0042] In a third aspect, the present application provides a modified PE, the preparation steps of which are as follows:

[0043] S1, firstly melt one or more of m-LLDPE, HDPE and MDPE, then spray it out, cool and stretch it to form filament fibers, and then lay it into a spunbond filament fiber web;

[0044] S2, filling the LDPE composite modified rubber into the spunbonded filament fiber web obtained in S1, and then heat-pressing and shaping it after curing, so as to obtain a modified PE sheet;

[0045] The LDPE composite modified rubber is prepared by melting one or more of LDPE composite acrylic resin and EVA resin.

[0046] By adopting the above technical solution, the obtained modified PE takes into account both the processability and the mechanical properties of the material to a great extent, thereby reducing the equipment requirements. The film can be produced with guaranteed quality and quantity by the more cost-effective calendering method, so the material has a very high application value. DETAILED DESCRIPTION

[0047] The present application is further described in detail below in conjunction with the examples. Except for the special instructions below, the raw materials used in the present application are all common commercially available materials.

[0048] LDPE: density 0.91-0.93 g / cm 3 , melt flow rate 4.0±0.2g / 10min;

[0049] m-LLDPE: Grade 5815, purchased from Dow Chemical Company;

[0050] MDPE: density 0.93-0.94g / cm 3 ; HDPE: density 0.95-0.96g / cm 3 ;

[0051] Polypropylene resin: density 0.91-0.92g / cm 3 , melt flow rate 3.0±0.2g / 10min;

[0052] EVA resin: density 0.92-0.94g / cm 3 , VA content 5-10%.

[0053] Preparation Example

[0054] Preparation Example 1-6

[0055] A modified PE sheet, the preparation steps of which are as follows:

[0056] S1. First, m-LLDPE and HDPE are melted and sprayed at a weight ratio of 1:0.5, and after cooling and stretching to form filament fibers, they are laid into a textile surface density of 400g / m 2 Spunbond filament fiber web;

[0057] S2, filling the LDPE composite modified rubber into the spunbonded filament fiber web obtained in S1 at a weight ratio of 1:1, and then after curing, hot pressing and shaping, to obtain a modified PE sheet;

[0058] In S2, the method of filling the LDPE composite modified liquid into the spunbond filament fiber web is a glue spraying method;

[0059] The components of the LDPE composite modified rubber used and their corresponding weight parts are shown in the following table:

[0060] Table: Components and weight percentages of LDPE composite modified rubber in Preparation Examples 1-6.

[0061]

[0062] Preparation Example 7-10

[0063] A modified PE sheet is different from Preparation Example 1 in that the raw materials used for the spunbonded filament web are different, as shown in the following table:

[0064] Table: Raw material usage for the spunbond filament webs in Preparation Examples 7-10.

[0065] Group Raw material usage of spunbond filament web Preparation Example 7 Composed of m-LLDPE and MDPE in a weight ratio of 1:0.6 Preparation Example 8 Composed of m-LLDPE and MDPE in a weight ratio of 1:0.8 Preparation Example 9 Composed of m-LLDPE and MDPE in a weight ratio of 1:1.0 Preparation Example 10 Composed of m-LLDPE and MDPE in a weight ratio of 1:0.2

[0066] Preparation Examples 11-15

[0067] A modified PE sheet, which is different from Preparation Example 1 in that the surface density of the spunbonded filament web and / or the amount of the composite modified rubber with LDPE are different, as shown in the following table:

[0068] Table: Raw material usage for the spunbond filament webs in Preparation Examples 11-15.

[0069]

[0070] Performance testing

[0071] First, the FFS single-layer heavy packaging films in each embodiment and comparative example were selected as test samples, and five groups were set in parallel for each group, and then the tensile strength MPa, tear strength g and durability and other properties were tested;

[0072] The specific testing standards and steps for tensile strength (MPa) refer to GB / T 1040.32006;

[0073] The specific testing standards and procedures for tear strength (g) refer to GB / T 16578.1;

[0074] The durability is tested through the drop test in GB / T 4857.5, where five groups of specimens are placed on a height of 3m and dropped freely once. If none of them are broken after falling, it is regarded as the basic qualified line (if any of the five groups is broken, it is regarded as unqualified).

[0075] Example

[0076] Examples 1-6

[0077] An ultra-thin single-layer FFS film, the usage of the raw material modified PE sheet is shown in the following table, and is prepared by the following preparation process:

[0078] A1. Calendering: First, the obtained modified PE sheet is calendered into a film blank by multi-stage calendering;

[0079] The specific steps of multi-stage calendering in A1 are as follows:

[0080] 1) Primary calendering: roller temperature 110°C, calendering roller rotation speed 25m / min;

[0081] 2) Secondary calendering: roller temperature 105°C, calendering roller rotation speed 15m / min;

[0082] 3) Three-stage calendering: roller temperature 95°C, calendering roller rotation speed 10m / min.

[0083] A2. Cooling and shaping: Then the film blank is cooled to room temperature through step-by-step cooling;

[0084] The specific steps of step-by-step cooling in A2 are as follows:

[0085] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 65°C;

[0086] 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 40°C;

[0087] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0088] A3. Rewinding and slitting: After the film blank is peeled off from the roller surface, it is slit and rewound to obtain the ultra-thin single-layer FFS film product with a film thickness of 0.10mm.

[0089] Table: Usage of modified PE sheets in Examples 1-6.

[0090] Group Usage of modified PE sheets Example 1 Prepared from Preparation Example 1 Example 2 Prepared from Preparation Example 2 Example 3 Prepared from Preparation Example 3 Example 4 Prepared by Preparation Example 4 Example 5 Prepared from Preparation Example 5 Example 6 Prepared from Preparation Example 6

[0091] Comparative Example 1

[0092] An ultra-thin single-layer FFS film, the components and corresponding weights of the raw materials are as follows: m-LLDPE 50kg; EVA resin 10kg; LDPE 10kg; LLDPE 25kg; masterbatch 5kg;

[0093] And it is made by the following co-extrusion process:

[0094] A1. Raw material mixing: first add each component of the above raw materials into a single screw extruder for mixing, with a screw diameter of 60 mm, a screw speed of 80 rpt / min, a temperature of 180° C., and a pressure of 40 MPa to obtain a fluid mixture;

[0095] A2, extrusion molding: the fluid mixture obtained in A1 is conveyed to the die head, and is fused and extruded at a temperature of 200°C, and then cooled by air at a temperature of 15°C, and a film bubble is formed at a blowing ratio of 2.0, and then cooled and shaped, and then pressed into a film strip;

[0096] A3, film strip drawing: the film strip obtained in A2 is stretched into a film at a stretching ratio of 5-10;

[0097] A4, Film cooling: 10℃ cooling water is passed into the cooling roller to cool the film on the roller;

[0098] A5. Reeling and slitting: After the film blank is peeled off from the roller surface, it is slit and reeled to obtain a single-layer FFS film product with a film thickness of 0.14mm.

[0099] The finished single-layer FFS films obtained in the above Examples 1-6 and Comparative Example 1 were tested for tensile strength MPa, tear strength g and durability (whether qualified or not) according to the above measurement steps, and the average values ​​of the test results were recorded in the following table.

[0100] Table: Performance test results of the finished single-layer FFS membranes in Examples 1-6 and Comparative Example 1.

[0101]

[0102] As can be seen from the above table, the finished single-layer FFS films (thickness 0.10 mm) prepared in Examples 1-6 all have excellent mechanical properties, with a tensile strength of up to 40.8-43.2 MPa, a tear strength of 145-156 g, and acceptable durability, which achieves a balance between performance and processability compared to Comparative Example 1;

[0103] The reasons may be as follows: the spunbond filament fiber web made by spinning one or more materials of m-LLDPE, HDPE and MDPE, not only takes into account the strength and toughness through the above-mentioned cross-linked network structure, but also significantly improves its own processability; and in the subsequent combination process with LDPE composite modified rubber, it can also form a composite structure with rigid material as the network vein and flexible material as the main filler. After hot pressing and shaping, this composite structure takes into account the processability and material mechanical properties to a great extent.

[0104] It can also be seen from Examples 1-6 that both the ratio of LDPE to EVA resin and the amount of polypropylene resin used will significantly affect the mechanical properties of the final product. The reason may be that the LDPE composite modified adhesives with different ratios have different permeability and adhesion, which affects the formation of the composite structure and cannot effectively achieve a balance between material processing ease and mechanical properties.

[0105] In addition, it can be known from the combination of Comparative Example 1 and common knowledge that: the present application benefits from the use of modified PE sheets, and the ultra-thin FFS film with a thickness of less than 0.14 mm can be produced by a more cost-effective calendering method, and thus has broad market prospects; while the extrusion molding method of the blended raw materials in Comparative Example 1 obviously does not have the above advantages, and its operation is complicated, and the equipment investment is high, so the application value is low.

[0106] Embodiment 7-15

[0107] An ultra-thin single-layer FFS film, which is different from Example 1 in that the usage of its raw material modified PE sheet is shown in the following table:

[0108] Table: Usage of modified PE sheets in Examples 7-10.

[0109] Group Usage of modified PE sheets Example 7 Prepared from Preparation Example 7 Example 8 Prepared from Preparation Example 8 Example 9 Prepared from Preparation Example 9 Example 10 Prepared from Preparation Example 10 Embodiment 11 Prepared from Preparation Example 11 Example 12 Prepared from Preparation Example 12 Embodiment 13 Prepared from Preparation Example 13 Embodiment 14 Prepared from Preparation Example 14 Embodiment 15 Prepared from Preparation Example 15

[0110] The finished single-layer FFS films obtained in the above Examples 7-15 were tested for tensile strength MPa, tear strength g and durability (whether qualified or not) according to the above measurement steps, and the average value of the test results was recorded.

[0111] Table: Performance test results of the finished single-layer FFS membranes in Examples 7-15.

[0112]

[0113] It can be seen from the above table that the finished single-layer FFS membranes (thickness 0.10 mm) prepared in Examples 1 and 7-15 have excellent mechanical properties, with a tensile strength of up to 40.0-41.2 MPa, a tear strength of 140-148 g, and acceptable durability. The reasons may be as follows: the spunbonded filament web of this material and textile surface density, in addition to effectively taking into account both strength and toughness through its own disordered network structure, is more firmly bonded to the LDPE composite modified liquid and can provide sufficient bonding sites. Moreover, the composite structure with a rigid material as the web and a flexible material as the main filler obtained by the above-mentioned method of combining non-woven fabrics and fillings has the characteristics of taking into account both processability and material mechanical properties compared to the direct mixing method, thereby realizing the production application of the calendering method.

[0114] In addition, it can be seen from Examples 1, 7-10 and Examples 1, 11-15 that:

[0115] 1) The raw materials for preparing the spunbond filament fiber web are preferably composed of m-LLDPE and MDPE in a weight ratio of 1:(0.5-0.8). Exceeding this ratio or using HDPE as a substitute will no longer enhance its performance;

[0116] 2) When the textile surface density of the spunbond filament web is 200-500g / m2 When the usage ratio of it to LDPE composite modified liquid is 1:(0.8-1.2), and its textile surface density is constant, other effects are small.

[0117] Example 16

[0118] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of multi-stage calendering in A1 are as follows:

[0119] 1) Primary calendering: roller temperature 110°C, calendering roller rotation speed 20m / min;

[0120] 2) Secondary calendering: roller temperature 105°C, calendering roller rotation speed 10m / min;

[0121] 3) Three-stage calendering: roller temperature 95°C, calendering roller rotation speed 10m / min.

[0122] Embodiment 17

[0123] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of multi-stage calendering in A1 are as follows:

[0124] 1) Primary calendering: roller temperature 105°C, calendering roller rotation speed 20m / min;

[0125] 2) Secondary calendering: roller temperature 100°C, calendering roller rotation speed 10m / min;

[0126] 3) Three-stage calendering: roller temperature is 90°C, and the rotation speed of the calendering roller is 10m / min.

[0127] Embodiment 18

[0128] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of multi-stage calendering in A1 are as follows:

[0129] 1) Primary calendering: roller temperature 115°C, calendering roller rotation speed 30m / min;

[0130] 2) Secondary calendering: roller temperature 110°C, calendering roller rotation speed 20m / min;

[0131] 3) Three-stage calendering: roller temperature is 100°C, and the rotation speed of the calendering roller is 15m / min.

[0132] Embodiment 19

[0133] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of multi-stage calendering in A1 are as follows:

[0134] 1) Primary calendering: roller temperature 110°C, calendering roller rotation speed 25m / min;

[0135] 2) Secondary calendering: roller temperature 95°C, calendering roller rotation speed 10m / min.

[0136] Embodiment 20

[0137] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of multi-stage calendering in A1 are as follows:

[0138] 1) Primary calendering: roller temperature 110°C, calendering roller rotation speed 25m / min;

[0139] 2) Secondary calendering: roller temperature 105°C, calendering roller rotation speed 15m / min;

[0140] 3) Three-stage calendering: roller temperature 95°C, calendering roller rotation speed 10m / min;

[0141] 4) Three-stage calendering: roller temperature 80°C, calendering roller rotation speed 10m / min.

[0142] The finished single-layer FFS films obtained in the above Examples 16-20 were tested for tensile strength MPa, tear strength g and durability (whether qualified or not) according to the above standards, and the average values ​​of the test results were recorded.

[0143] Table: Performance test results of the finished single-layer FFS membranes in Examples 16-20.

[0144]

[0145] It can be seen from the above table that the finished single-layer FFS films (thickness 0.10 mm) prepared in Examples 1 and 16-20 have excellent mechanical properties, with a tensile strength of up to 40.0-40.8 MPa, a tear strength of 141-146 g, and durability that is acceptable. The reasons may be as follows: This application is based on the characteristics of the PE sheet composite structure and is adjusted to a step-by-step cooling method, which can make full use of the waste heat from the previous calendering, combined with specific temperature, rotation speed and corresponding cooling process, without the need for additional heating or temperature control, and the product thickness and size stability are excellent.

[0146] In addition, it can be seen from Examples 1 and 16-20 that the three-stage calendering process is preferred. Reducing the number of stages on this basis will be detrimental to the quality of the finished product, but increasing the number of stages will no longer improve its performance;

[0147] The preferred temperature range and rotation speed are as follows, and the most preferred rotation speed is decreased as the temperature increases:

[0148] 1) Primary calendering: roller temperature 105-115°C, calendering roller rotation speed 20-30m / min;

[0149] 2) Secondary calendering: roller temperature 100-110°C, calendering roller rotation speed 10-20m / min;

[0150] 3) Three-stage calendering: roller temperature 90-100℃, calendering roller rotation speed 10-15m / min.

[0151] Embodiment 21

[0152] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of step-by-step cooling in A2 are as follows:

[0153] The specific steps of step-by-step cooling in A2 are as follows:

[0154] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 50°C;

[0155] 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 30°C;

[0156] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0157] Embodiment 22

[0158] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of step-by-step cooling in A2 are as follows:

[0159] The specific steps of step-by-step cooling in A2 are as follows:

[0160] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 80°C;

[0161] 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 50°C;

[0162] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0163] Embodiment 23

[0164] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of step-by-step cooling in A2 are as follows:

[0165] The specific steps of step-by-step cooling in A2 are as follows:

[0166] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 80°C;

[0167] 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 30°C;

[0168] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0169] Embodiment 24

[0170] An ultra-thin single-layer FFS film, which is different from Example 1 in that the specific steps of step-by-step cooling in A2 are as follows:

[0171] The specific steps of step-by-step cooling in A2 are as follows:

[0172] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 50°C;

[0173] 3) Secondary water cooling: Water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0174] The finished single-layer FFS films obtained in the above Examples 21-24 were tested for tensile strength MPa, tear strength g and durability (whether qualified or not) according to the above standards, and the average values ​​of the test results were recorded.

[0175] Table: Performance test results of the finished single-layer FFS membranes in Examples 21-24.

[0176]

[0177] It can be seen from the above table that the single-layer FFS film products (thickness 0.10mm) prepared in Examples 1 and 21-24 have excellent mechanical properties, with a tensile strength of up to 40.2-41.0MPa, a tear strength of 142-146g, and durability that are all qualified; the reasons may be analyzed as follows: Compared with direct cooling, the multi-stage cooling method in this application can effectively avoid the thickness or size fluctuation of the product due to inconsistent shrinkage force. Visually, the thickness of the finished film is uniform, and there is no deformation, warping or other adverse conditions.

[0178] In addition, it can be seen from Examples 1, 21-24 that the preferred cooling method is to alternately cool with water and air, and the temperature difference of each stage does not exceed 50°C, preferably 20-30°C. The most preferred conditions are as follows:

[0179] 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 50-80°C;

[0180] 2) Secondary water cooling: Blow cold air again to reduce the film temperature to 30-50℃;

[0181] 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

[0182] 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 modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An ultra-thin single-layer FFS film, characterized in that: Made by calendering modified PE sheets; The preparation steps of the modified PE sheet are as follows: S1, firstly melt one or more of m-LLDPE, HDPE and MDPE, then spray it out, cool and stretch it to form filament fibers, and then lay it into a spunbond filament fiber web; S2, filling the LDPE composite modified rubber into the spunbonded filament fiber web obtained in S1, and then heat-pressing and shaping it after curing, so as to obtain a modified PE sheet; The usage ratio of the spunbonded filament fiber web to the LDPE composite modified rubber is 1:(0.8-1.2), and its textile surface density is 200-500 g / m 2 ; The LDPE composite modified rubber is composed of the following components in parts by weight: 80-120 parts of LDPE, 0-40 parts of acrylic resin and 40-80 parts of EVA resin.

2. The ultra-thin single-layer FFS film according to claim 1, characterized in that: The raw materials for preparing the spunbonded filament fiber web are composed of m-LLDPE and MDPE in a weight ratio of 1:(0.5-0.8).

3. The ultra-thin single-layer FFS film according to claim 1, characterized in that: The VA content of the EVA resin is 5-10%.

4. The ultra-thin single-layer FFS film according to any one of claims 1 to 3, characterized in that: In S2, the method of filling the LDPE composite modified rubber into the spunbonded filament fiber web is a glue pouring method; Specific parameter conditions are: glue spraying amount is 160-600g / m 2 .

5. The method for preparing the ultra-thin single-layer FFS membrane according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: A1. Calendering: First, the obtained modified PE sheet is calendered into a film blank by multi-stage calendering; A2. Cooling and shaping: Then the film blank is cooled to room temperature through step-by-step cooling; A3. Rewinding and slitting: After the film blank is peeled off from the roller surface, the film blank is slit and rewound to obtain the ultra-thin single-layer FFS film product.

6. The method for preparing the ultra-thin single-layer FFS membrane according to claim 5, characterized in that: The specific steps of multi-stage calendering in A1 are as follows: 1) Primary calendering: roller temperature 105-115°C, calendering roller rotation speed 20-30m / min; 2) Secondary calendering: roller temperature 100-110℃, calendering roller rotation speed 10-20m / min; 3) Three-stage calendering: roller temperature 90-100℃, calendering roller rotation speed 10-15m / min.

7. The method for preparing the ultra-thin single-layer FFS membrane according to claim 6, characterized in that: The specific steps of step-by-step cooling in A2 are as follows: 1) Primary water cooling: First, water is passed through the cooling roller to reduce the film temperature to 50-80°C; 2) Secondary air cooling: Blow cold air again to reduce the film temperature to 30-50℃; 3) Three-stage water cooling: Finally, water is passed through the cooling rollers to reduce the film temperature to room temperature.

Images