CN106867089A - A kind of gas permeability laminated film and preparation method thereof - Google Patents

Abstract

The invention discloses a breathable composite film and a preparation method thereof. The composite film is prepared from the following components by weight percentage: 60%-82% polyolefin resin polymer, 2%-8% micro-nano crystal fiber Prime particles, 0.4%-1% antioxidant, 15%-30% dispersant, 0.1%-0.5% lubricant, 0.2%-1% coupling agent. The preparation method is as follows: uniformly disperse the micro-nanocrystalline cellulose aqueous dispersion and the coupling agent; then add the dispersant and mix evenly, and dry to obtain the pretreated filler; the obtained pretreated filler, polyolefin resin, antioxidant , Lubricant is added to the twin-screw extruder, and the breathable composite film composition is obtained through melt extrusion, cooling and granulation, and the flat film is prepared by hot calendering; then immersed in the cleaning agent, ultrasonicated, and dried; two-way stretching and Heat-setting treatment to obtain a breathable composite film. The composite film has high air permeability and excellent mechanical properties.

Description

A kind of breathable composite film and preparation method thereof

technical field

The invention relates to the field of composite films, in particular to a breathable composite film and a preparation method thereof.

Background technique

Cellulose is the most abundant natural renewable polymer compound in nature. Products based on cellulose are widely used in fuel ethanol, papermaking, permeable membranes, plastics, electronic products, medical engineering, electrical engineering, and industrial processing. , has excellent characteristics such as environmental protection and degradability, good thermal stability, high chemical stability, and high dielectric constant. In recent years, a large number of researchers have devoted themselves to modifying and strengthening cellulose to prepare high-performance film materials, mainly used for filtration, permeable membranes and lithium battery separator materials. The traditional gas permeable film is a polymer film filled with a certain amount of inorganic particle filler. When stretched, a hole with a controllable size is formed around the inorganic filler, which allows the passage of gases such as water vapor and air, while not allowing liquid to pass through. It is mainly used for the production of finished products such as baby diapers, feminine sanitary napkins, and outdoor sportswear. In industrial production, the composition of the breathable film is stretched after extrusion, granulation, casting or blow molding at a certain temperature. At this time, only the polymer matrix resin can be stretched, and the added inorganic particles The filler cannot be stretched, resulting in tiny pores around the inorganic particle filler through which only gases such as water vapor or air can pass.

Chinese patent 201110203184.8 discloses a composition and a preparation method of a low-air-permeable air-permeable membrane. Its components include: a polyolefin resin mixture, an air-permeable regulator, surface-modified micron-sized inorganic particles, an antioxidant, and a lubricant and coupling agents. Its advantage is that the nano-micron inorganic filler can improve the mechanical properties of the breathable film, and the surface coupling modified inorganic particles increase the compatibility with the polyolefin matrix resin, but the disadvantage is that the high addition amount (30%-55% ) micron inorganic particles can not be uniformly dispersed in the matrix resin, thus affecting the uniformity of air permeability of the film material.

Chinese patent 201110125458.6 discloses a polyolefin film and its preparation method, its components include: polyolefin resin, pore forming agent and extractant. Its advantage is that the polypropylene hydrocarbon film prepared by the traditional wet method has a small structure and a large number, but it adopts a two-step extraction process with a high volume percentage concentration, and the extraction solvent is N, N'-dimethylformamide, dichloro Methane, chloroform, etc. are highly polluting and toxic solvents, which can cause great harm to the human body and the environment.

Contents of the invention

The object of the present invention is to provide a breathable composite film and a preparation method thereof, so as to prepare a composite film with high air permeability and excellent mechanical properties.

The purpose of the present invention is achieved through the following technical solutions.

A breathable composite film, the breathable composite film is prepared from the following components by weight percentage:

Preferably, the polyolefin resin mixture is linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), homopolypropylene (HPP) , ethylene-propylene copolymer (EPM), ethylene-butene copolymer (ENR), ethylene-octene copolymer (POE), ethylene-acrylate-glycidyl methacrylate (GMA) and ethylene-propylene-non- Single or blends of conjugated dienes (EPDM).

Preferably, the selected micro-nanocrystalline cellulose particles have a particle size distribution of 50nm-50μm; the micro-nanocrystalline cellulose is preferably selected from at least one of hemp, wheat straw, straw, bagasse, cotton and plant seed coat.

Preferably, the dispersant is polyethylene glycol with different degrees of polymerization: more preferably one of PEG-200, PEG-400, PEG-600, PEG-1000, PEG-2000, PEG-4000 and PEG-6000 It is mainly used to coat micro-nanocrystalline cellulose particles to prevent them from agglomerating, and to form more uniformly dispersed air-permeable channels after being removed by immersion.

Preferably, the lubricant is at least one of higher fatty acid lipids, metal soaps, fatty amides and paraffin. More preferred are stearic acid, zinc stearate, calcium stearate, oleic acid amide, low-molecular PE wax, low-molecular PP wax, OPE (oxidized polyethylene) wax, natural paraffin, liquid paraffin, and the like. The selected lubricant can reduce the mutual friction between the material and the processing machinery and material molecules, thereby improving the processing performance of the composite and improving the thermal stability of the composite material.

Preferably, the micro-nanocrystalline cellulose is treated with a coupling agent, and the coupling agent used is a silane coupling agent containing more than one group in amino group, mercapto group, epoxy group, acyloxy group and vinyl group; further Preferred are γ-aminopropyltrimethoxysilane (KH590), γ-aminopropyltriethoxysilane (KH550), γ-(2,3-glycidoxy)propyldimethoxysilane, γ -(2,3-Glycidoxy)propyltrimethoxysilane, γ-(Methacryloxy)propyltrimethoxysilane, γ-Mercaptopropyltriethoxysilane (KH580), γ- One or more of mercaptopropyltrimethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

Preferably, the antioxidant is more than one of phenols, aromatic amines, hindered phenols, phosphites and diester of thiodipropionate; more preferably antioxidants 1010, 1076, 164, 264, CA, DNP, DLTP, TNP, BHT. When antioxidants exist in a small amount in polymer processing and application systems, they can delay or inhibit the oxidation process of polymers, thereby avoiding color changes and prolonging service life.

A kind of preparation method of breathable composite film described above, comprises the steps:

(1) uniformly dispersing the micro-nanocrystalline cellulose particle water dispersion and coupling agent to obtain a pre-dispersion;

(2) Mix the predispersion liquid and the dispersant evenly, and dry in an oven to obtain the pretreatment filler;

(3) Add the obtained pretreatment filler, polyolefin resin mixture, antioxidant and lubricant into the twin-screw extruder through the feeding system, and make a breathable composite film through melt extrusion, cooling and granulation Composition pellets;

(4) Heat-calender or extrude the air-permeable composite film composition pellets at a temperature of 170-190°C and a pressure of 20t-40t to prepare a flat composite film;

(5) Immerse the flat composite film in the cleaning agent, remove the dispersant through ultrasonic waves and dry it;

(6) Biaxially stretch the dry composite film obtained in step (5) with a stretch ratio of 0.5-1.5, and heat-setting treatment at 80-120°C to fully orient the molecular chains of the substrate in the film and heat-setting The treatment time is 5-15 minutes, and a breathable composite film with micro-nano holes is prepared.

Preferably, the twin-screw extruder is a co-rotating twin-screw extruder, the length-to-diameter ratio L/D is 40-50, the screw speed is ≥80 rpm, and the extrusion temperature is set at 180-220°C.

Preferably, the ultrasonic frequency in step (5) is 40-200 kHz; the cleaning agent is at least one of water, ethanol, isopropanol and acetone.

Through the actual measurement of the water permeability of the air-permeable composite film, it can be analyzed that the content of micro-nanocrystalline cellulose affects the mechanical properties of the composite membrane material. In addition, the type and amount of the dispersant determine the water permeability of the composite membrane material to a large extent. .

Compared with prior art, the present invention has following advantage:

(1) In the present invention, adding rigid rod-shaped organic particle micro-nanocrystalline cellulose to polyolefin resin can improve the hydrophilicity, thermal stability and mechanical properties of the composite film;

(2) The present invention carries out coupling treatment to the micro-nanocrystalline cellulose surface, can improve its interfacial compatibility with matrix resin;

(3) The addition of dispersant polyethylene glycol in the present invention can effectively prevent the micro-nanocrystalline cellulose particles from agglomerating;

(4) The cleaning agent used in the post-treatment process of the composite film of the present invention is environmentally friendly, safe, recyclable and reusable;

(5) The present invention carries out immersion treatment before carrying out stretching orientation to composite film, removes dispersing agent, the pore size of the obtained composite film finished product is smaller, quantity is more, is easy to control the shape of pore in addition;

(6) The present invention has the characteristic that the membrane pores present a micro-nano non-linear channel structure.

Description of drawings

Fig. 1 is a surface scanning electron microscope image of the air-permeable composite film of the present invention.

Fig. 2 is a cross-sectional scanning electron microscope image of the air-permeable composite film of the present invention.

detailed description

Embodiments of the present invention will be further described below in combination with examples and accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

(1) 3.2kg concentration is 25g/L micronanocrystalline soybean seed coat cellulose aqueous dispersion liquid (particle diameter is 50nm-2 μ m) and 6g silane coupling agent KH580 in high-speed disperser (1000rpm), disperse again Add 300g dispersant polyethylene glycol PEG-200 and mix homogeneously in a high-speed mixer (1000rpm), and dry the mixture in an oven to obtain a pretreatment filler;

(2) 500g linear low density polyethylene (LLDPE), 100g ethylene-acrylate-glycidyl methacrylate (GMA), pretreatment filler, 4g phenolic 264 and phosphite BHT antioxidant, 10g lubricant Agent calcium stearate is premixed by high-speed mixer (1000rpm), gets premixed material;

(3) The premixed material is added to the feed port of the extruder through a metering feeder, melted and extruded by a co-rotating twin-screw extruder, cooled and granulated to obtain a finished gas permeable composite film composition. The aspect ratio of the twin-screw extruder used in the above processing process is 50, the screw speed is 90rpm, and the extrusion temperature is set as: feeding port 180°C, melting section 210°C, nose die 180°C;

(4) hot rolling the composite film composition pellets at a temperature of 170°C and a pressure of 25t to prepare a flat film;

(5) The composite film is immersed in deionized water, and the dispersant is removed by ultrasonic (200kHz) and dried;

(6) Biaxially stretch the dry composite film with a stretch ratio of 0.5, and perform heat setting treatment at 80°C for 5 minutes, and finally prepare a finished breathable film with a film thickness of 60-150 μm, according to With the above formula and preparation process, the air permeability of the obtained air-permeable composite film can reach 2460-6530g/(m ² ·24h).

The scanning electron micrographs of the surface and cross-section of the air-permeable composite film prepared in this example are shown in Figure 1 and Figure 2, respectively. The air-permeable pores are distributed in a non-linear space network structure, with many, wide and uniform pores, and the pore size is 100nm-10μm, the porosity reaches 50%.

Example 2

(1) Disperse 2.5kg of microcrystalline cotton cellulose aqueous dispersion (particle size: 500nm-10μm) with a concentration of 20g/L and 10g of silane coupling agent KH550 in a high-speed disperser (1000rpm), and then add the dispersant 225g Polyethylene Glycol PEG-400 is mixed in high-speed mixer (1000rpm), and its mixture is dried in baking oven and obtains pretreatment filler;

(2) 600g low-density polyethylene (LDPE), 100g ethylene-propylene copolymer (EPM), pretreatment filler, 4g hindered phenolic antioxidant 1010, 10g lubricant zinc stearate are passed through high-speed mixer (1200rpm) Perform premixing to obtain premixed materials;

(3) The premixed material is added to the feed port of the extruder through a metering feeder, melted and extruded by a co-rotating twin-screw extruder, cooled and granulated to obtain the air-permeable composite film composition pellets. The aspect ratio of the twin-screw extruder used in the above process is 40, the screw speed is 80rpm, and the extrusion temperature is set as: feeding port 180°C, melting section 205°C, nose die 180°C;

(4) Extrude the composite film composition pellets at a temperature of 180°C and a pressure of 40t to prepare a flat composite film;

(5) The composite film is immersed in ethanol, and the dispersant is removed by ultrasonic (100kHz) and dried;

(6) Biaxially stretch the dry composite film with a stretch ratio of 1.5, and heat setting treatment at 100°C for 15 minutes, and finally prepare a finished breathable film with a film thickness of 60-150 μm, according to With the above formula and preparation process, the air permeability of the obtained air-permeable composite film can reach 2710-4890g/(m ² ·24h).

Example 3

(1) Disperse 0.5 kg of microcrystalline hemp cellulose aqueous dispersion (with a particle size of 2 μm-50 μm) and 2 g of silane coupling agent KH590 in a high-speed disperser (1000 rpm) evenly, and then add the dispersant 150g polyethylene glycol PEG1000 is mixed homogeneously in high-speed mixer (1000rpm), and its mixture is dried in baking oven and obtains pretreatment filler;

(2) 700g high-density polyethylene (HDPE), 120g ethylene-octene copolymer (POE), pretreatment filler, 7g hindered phenolic antioxidant 1076 and 1g lubricant low-molecular PE wax are passed through a high-speed mixer (1200rpm ) for premixing;

(3) The premixed material is added to the feed port of the extruder through a metering feeder, melted and extruded by a co-rotating twin-screw extruder, cooled and granulated to obtain a finished gas permeable composite film composition. The aspect ratio of the twin-screw extruder used in the above processing process is 50, the screw speed is 100 rpm, and the extrusion temperature is set as: feeding port 180°C, melting section 220°C, nose die 180°C;

(4) hot rolling the composite film composition pellets at a temperature of 190°C and a pressure of 20t to prepare a flat film;

(5) Dip the composite film in ethanol, remove the dispersant through ultrasonic (40kHz) and dry it;

(6) Biaxially stretch the dry composite film with a stretch ratio of 1, and heat setting treatment at 120°C for 10 minutes, and finally prepare a breathable film product with a film thickness of 60-150 μm, according to With the above formula and preparation process, the air permeability of the obtained air-permeable composite film can reach 2710-6500g/(m ² ·24h).

The tensile strength of the prepared breathable composite film samples was tested according to the GB13022 standard.

The air permeability (WVT) of the prepared breathable composite film is measured according to GB/T12704-91, and the prepared breathable composite film is covered and sealed on the open surface of the standard moisture-permeable cup and in the standard moisture-permeable cup by the positive cup evaporation method. Inject a certain amount of distilled water and place it in a constant temperature and humidity chamber with a temperature of 38°C and a relative humidity of 2%. The change in weight within 24 hours is the air permeability of the breathable composite film.

The finished gas permeable composite films prepared in the above three examples exhibit the following structural features: the gas permeable channels are distributed in a non-linear spatial network structure, with many, wide and uniform pores, as shown in Figure 1 and Figure 2 .

The above examples are not intended to limit the amount of the composition of the present invention, and any modifications or equivalent changes made according to the composition, amount and preparation method of the composition of the present invention are within the technical protection scope of the present invention.

Claims (10)

1. a kind of gas permeability laminated film, it is characterised in that the gas permeability laminated film is by following components in percentage by weight system It is standby to form：

2. a kind of gas permeability laminated film according to claim 1, it is characterised in that described polyolefin resin mixture It is LLDPE, low density polyethylene (LDPE), medium density polyethylene, high density polyethylene (HDPE), HOPP, ethene-the third Alkene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-acrylate-GMA and One or more in ethylene-propylene-non-conjugated diene of blend.

3. a kind of gas permeability laminated film according to claim 1, it is characterised in that the micro nanocrystalline cellulose granules Grain size be distributed as 50nm-50 μm.

4. a kind of gas permeability laminated film according to claim 1, it is characterised in that the antioxidant is phenols, fragrance One or more of amine, Hinered phenols, phosphorous acid lipid and thio-2 acid dibasic acid esters.

5. a kind of gas permeability laminated film according to claim 1, it is characterised in that the dispersant is different polymerization journeys The polyethylene glycol of degree.

6. a kind of gas permeability laminated film according to claim 1, it is characterised in that the lubricant is higher fatty acids One or more of lipid, metal soap, fatty acyl amide and paraffin.

7. a kind of gas permeability laminated film according to claim 1, it is characterised in that the coupling agent be containing amino, The silane coupler of one or more of sulfydryl, epoxy radicals, acyloxy and vinyl group.

8. the method for preparing a kind of gas permeability laminated film described in claim any one of 1-7, it is characterised in that including as follows Step：

(1) micro nanocrystalline cellulose granules aqueous dispersions and coupling agent are uniformly dispersed, obtain pre-dispersed liquid；

(2) it is pre-dispersed liquid and dispersant is uniform, and acquisition pretreated filler is dried in an oven；

(3) resulting pretreated filler, polyolefin resin mixture, antioxidant, lubricant are added to by feed system In double screw extruder, gas permeability laminated film constituent pellet is obtained by melting extrusion, cooling and granulation；

(4) gas permeability laminated film constituent pellet is carried out into hot pressing at 170-190 DEG C of temperature and the pressure of 20t-40t Prolong or extrude and prepare smooth laminated film；

(5) by smooth laminated film immersion cleaning agent, dispersant and dried process are removed through ultrasound；

(6) step (5) gained dry composite film is carried out into biaxial tension, stretching ratio is 0.5-1.5, in 80-120 DEG C of condition Under carry out thermal finalization treatment, the substrate molecule chain in film is fully orientated, thermal finalization process time be 5-15min, be obtained tool There is the gas permeability laminated film of micro-nano hole.

9. preparation method according to claim 8, it is characterised in that the double screw extruder described in step (3) is in the same direction Rotating twin-screw extruder, draw ratio L/D is 40-50, and screw speed >=80rpm, extrusion temperature is 180-220 DEG C.

10. preparation method according to claim 8, it is characterised in that the frequency of step (5) ultrasound is 40- 200kHz；The cleaning agent is one or more of water, ethanol, isopropanol and acetone.