CN111892761A

CN111892761A - High-breathability cast film and preparation method thereof

Info

Publication number: CN111892761A
Application number: CN202010825836.0A
Authority: CN
Inventors: 郭永富; 黄福忠; 廖锡超; 吴镇华
Original assignee: Dongguan Saimei Plastic Products Co ltd
Current assignee: Dongguan Saimei Plastic Products Co ltd
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2020-11-06

Abstract

The invention relates to the technical field of cast film production, and discloses a high-permeability cast film which is prepared from the following raw materials in parts by weight: polyethylene, methanol, propylene-ethylene copolymer, inorganic filler, reinforcing agent, coupling agent and heat stabilizer. The preparation method comprises the following steps: mixing all components of the casting film, adding the mixture into an internal mixer for kneading and banburying, then extruding and granulating by a double-screw extruder, preparing a film by adopting a casting method, stretching and shaping the film in a single direction, dissolving methanol in the film by a steam hot water tank, and drying to obtain the high-permeability casting film. This application adopts methyl alcohol to reduce the capillary force of inorganic filler particle coalescence, avoids inorganic filler particle to influence self performance because of reuniting, dissolves methyl alcohol in aqueous when the steam hot-water tank is being passed through simultaneously, makes to form on the curtain coating membrane and has ventilative waterproof micropore to improve the air permeability of curtain coating membrane.

Description

High-breathability cast film and preparation method thereof

Technical Field

The invention relates to the technical field of cast film production, in particular to a high-air-permeability cast film and a preparation method thereof.

Background

The cast film is widely applied in daily life, has excellent air permeability and waterproof performance and excellent transparency, is widely applied to plastic paper, packaging bags, sanitary articles such as diapers and the like, medical garments and the like, is formed by mixing thermoplastic polymers and fillers, and is a non-stretching non-oriented frontal cast film produced by melt casting quenching.

In the related technology, for example, the chinese patent application publication No. CN110183768A discloses a high-smoothness master batch for cast film, a preparation method thereof, and a high-smoothness cast film, wherein the high-smoothness master batch for cast film comprises the following components in parts by weight: 40-80 parts of PE powder; 2-8 parts of a main antioxidant; 2-8 parts of an auxiliary antioxidant; 2-8 parts of zinc stearate; 2-8 parts of an antistatic agent; 5-20 parts of a slipping agent; 2-8 parts of an opening agent. The cast film prepared by using the high-smoothness master batch solves the problems that an additive in raw materials is easy to separate out on a chill roll and the smoothness performance of a film is obviously reduced after the film is placed for one month or two months in a high-speed packaging production line of the cast film.

Aiming at the technical characteristics, the casting film used in the fields of sanitary products such as diapers and the like, medical clothing products and the like has higher requirement on the air permeability, the high-smoothness casting film obtained by the invention does not relate to the improvement on the air permeability, has low air permeability, cannot meet the product requirement with higher requirement on the air permeability, and has limited application field.

Disclosure of Invention

In view of the defects of the prior art, the first object of the invention is to provide a casting film with high air permeability, which has the advantage of improving the air permeability of the casting film and expands the application range of the casting film.

A second object of the present invention is to provide a method for producing a casting film with high air permeability, which can produce a casting film with high air permeability.

In order to achieve the first object, the invention provides the following technical scheme:

a high-permeability casting film is prepared from the following raw materials in parts by weight:

polyethylene: 85-110 parts;

methanol: 13-18 parts;

propylene-ethylene copolymer: 35-46 parts;

inorganic filler: 75-95 parts;

reinforcing agent: 0.5 to 1.8 portions;

coupling agent: 0.8 to 1.6 portions;

heat stabilizer resistance: 1.5-2.3 parts;

wherein the inorganic filler is silicon dioxide and calcium carbonate according to a mass ratio of 1:3, and mixing the components in a ratio of 3.

By adopting the technical scheme, the surface tension of the methanol is small, the methanol can replace the water adsorbed on the surfaces of the inorganic filler particles during mixing, and the hydrogen bond effect among the inorganic particles is reduced, so that the capillary force for conglomerating the inorganic filler particles is reduced, the influence of agglomeration on the performance of the inorganic filler particles is avoided, and meanwhile, the methanol is dissolved in water when the inorganic filler particles pass through a steam hot water tank, so that air-permeable and waterproof micropores are formed on the casting film, and the air permeability is improved; in addition, the coumarone resin has a reinforcing effect on the casting film, and can improve mechanical properties.

Further, the calcium carbonate is synthetic calcium carbonate, and the preparation method of the synthetic calcium carbonate comprises the following steps:

s01, weighing 5-12 parts by weight of calcium oxide, adding distilled water, controlling the temperature system to be 60-80 ℃, and stirring for dissolving to obtain a calcium hydroxide solution with the mass concentration of 0.1 mol/L;

s02, weighing 1-2 parts by weight of polyacrylic acid, adding distilled water, controlling the temperature system to be 95-105 ℃, and stirring for dissolving to obtain a polyacrylic acid solution with the concentration of 0.75 g/L;

s03, adding the calcium hydroxide solution obtained in the step S01 into a polyacrylic acid solution, controlling the temperature system to be 85-100 ℃, and stirring and mixing for 30-50 min to prepare a mixed solution;

and S04, introducing carbon dioxide gas at the bottom of the mixed solution, controlling the flow rate of the introduced gas to be 0.1L/min, simultaneously stirring at the stirring speed of 150-300 rpm, stopping introducing the carbon dioxide gas when the pH value of the detection system reaches 7, filtering, washing and drying to obtain the synthetic calcium carbonate.

By adopting the technical scheme, polyacrylic acid is used as an organic matrix, the relative growth rates of different crystal faces are changed, the purpose of controlling the crystal morphology is achieved, the synthesized calcium carbonate has a special morphology, the self performance of the calcium carbonate is changed, and the air permeability and the mechanical performance of the casting film are obviously improved.

Further, the heat stabilizer is formed by mixing calcium stearate and epoxy linseed oil according to the mass ratio of 3: 1.

By adopting the technical scheme, the calcium stearate and the epoxy seed oil are mixed according to a certain proportion to serve as the heat-resistant stabilizer, and the calcium stearate and the epoxy seed oil have synergistic effect, so that the heat resistance stability of each component in the casting film raw material can be improved, the using amount of the heat-resistant stabilizer is reduced, and the material is saved.

Further, the coupling agent is one or a mixture of KH792, KH560 or A-172.

By adopting the technical scheme, the coupling agent can improve the interface combination between organic matters of polyethylene and propylene-ethylene copolymers and inorganic filler, improve the dispersibility of the inorganic filler and further obtain the casting film with good air permeability and mechanical property.

Further, the reinforcing agent is one or a mixture of lignin, carbon black and coumarone resin.

By adopting the technical scheme, the lignin, the coumarone resin and the carbon black have a reinforcing effect on the casting film, so that the tensile strength and the puncture resistance of the casting film can be improved, and the mechanical property is improved.

Further, the particle size of the silicon dioxide is 2-5 μm.

Further, the casting film is prepared from the following raw materials in parts by weight:

polyethylene: 85 parts of a mixture;

methanol: 13 parts;

propylene-ethylene copolymer: 46 parts of (a);

inorganic filler: 95 parts of (C);

coumarone resin: 0.5 part;

KH 792: 1.2 parts;

heat stabilizer resistance: 1.5 parts;

the heat stabilizer is prepared by mixing calcium stearate and epoxy linseed oil according to the mass ratio of 3:1, and the inorganic filler is prepared from silicon dioxide and synthetic calcium carbonate according to the mass ratio of 1:3, the particle size of the silicon dioxide is 2-5 μm, and the preparation method of the synthetic calcium carbonate comprises the following steps:

s01, weighing 8kg of calcium oxide by weight, adding distilled water, controlling the temperature system to be 80 ℃, and stirring for dissolving to obtain a calcium hydroxide solution with the mass concentration of 0.1 mol/L;

s02, weighing 1kg of polyacrylic acid in parts by weight, then adding distilled water, controlling the temperature system to be 105 ℃, and stirring for dissolving to obtain a polyacrylic acid solution with the concentration of 0.75 g/L;

s03, adding the calcium hydroxide solution obtained in the step S01 into a polyacrylic acid solution, controlling the temperature system to be 100 ℃, and stirring and mixing for 50min to obtain a mixed solution;

and S04, introducing carbon dioxide gas at the bottom of the mixed solution, controlling the flow rate of the introduced gas to be 0.1L/min, simultaneously stirring at the stirring speed of 250rpm, stopping introducing the carbon dioxide gas when the pH value of the detection system reaches 7, filtering, washing and drying to obtain the synthetic calcium carbonate.

By adopting the technical scheme, the ratio of the content of each component of the casting film and the process parameters are specifically limited, and the casting film with better air permeability and mechanical property can be obtained.

In order to achieve the second object, the invention provides the following technical scheme:

a method for preparing a high-permeability casting film comprises the following steps:

s1, mixing polyethylene, methanol, propylene-ethylene copolymer, silicon dioxide, calcium carbonate and heat stabilizer, adding into an internal mixer for kneading and banburying, wherein the banburying temperature is 150-190 ℃, and the banburying time is 5-15 min;

s2, extruding and granulating the product obtained in the step S1 by using a double-screw extruder, wherein the rotating speed of the extruder is 200-500 rpm, and the temperature is 140-180 ℃;

s3, preparing the plastic particles obtained in the step S2 into a film by adopting a tape casting method, wherein the film making temperature is 200-250 ℃, and then performing unidirectional stretching on the tape-cast film, wherein the stretching temperature is 60-90 ℃, the stretching speed is 80-120 mm/min, and the stretching setting is 20-35 min;

and S4, passing the casting film prepared in the step S3 through a steam hot water tank, staying for 4-8 min, dissolving the methanol in the film, and drying to obtain the high-permeability casting film.

By adopting the technical scheme, the casting film is prepared by adopting a banburying and double-screw mixing mode, the mixing uniformity of all components of the casting film can be improved, and the casting film prepared by the scheme has better air permeability and mechanical property.

Further, initially in step S1, silica and calcium carbonate were washed with methanol in advance for 3 times in succession, dried and then charged into an internal mixer.

By adopting the technical scheme, the silicon dioxide and the calcium carbonate are washed in advance by using the methanol, the surface tension of the methanol is small, water molecules adsorbed on the surfaces of the silicon dioxide and the calcium carbonate can be replaced, and the agglomeration of particles is further reduced, so that the performances of the silicon dioxide and the calcium carbonate are improved, and the air permeability and the mechanical performance of the cast film are improved.

In conclusion, the invention has the following beneficial effects:

firstly, the surface tension of the methanol is small, the methanol can replace water adsorbed on the surfaces of the inorganic filler particles during mixing, and the hydrogen bond effect among the inorganic particles is reduced, so that the capillary force of the inorganic filler particles for coalescence is reduced, the influence of agglomeration on the performance of the inorganic filler particles is avoided, and meanwhile, the methanol is dissolved in water when the inorganic filler particles pass through a steam hot water tank, so that air-permeable and waterproof micropores are formed on a casting film, and the air permeability is improved; in addition, the coumarone resin has a reinforcing effect on the casting film, and can improve mechanical properties.

Secondly, polyacrylic acid is used as an organic matrix, the relative growth rates of different crystal faces are changed, the purpose of controlling the crystal morphology is achieved, the synthesized calcium carbonate has a special morphology, the self performance of the calcium carbonate is changed, and the air permeability and the mechanical performance of the casting film are obviously improved.

And thirdly, the silicon dioxide and the calcium carbonate are washed in advance by using methanol, the surface tension of the methanol is small, water molecules adsorbed on the surfaces of the silicon dioxide and the calcium carbonate can be replaced, and the agglomeration of particles is further reduced, so that the performances of the silicon dioxide and the calcium carbonate are improved, and the air permeability and the mechanical performance of the casting film are improved.

Detailed Description

The present invention will be described in further detail with reference to examples.

The sources of the raw materials used in the following preparations, examples and comparative examples are shown in table 1 below:

TABLE 1 sources of raw materials

Preparation example

Preparation example 1

A synthetic calcium carbonate, comprising the steps of:

s01, weighing 5kg of calcium oxide by weight, adding distilled water, controlling the temperature system to be 70 ℃, and stirring for dissolving to obtain a calcium hydroxide solution with the mass concentration of 0.1 mol/L;

s02, weighing 2kg of polyacrylic acid in parts by weight, then adding distilled water, controlling the temperature system to be 100 ℃, and stirring for dissolving to obtain a polyacrylic acid solution with the concentration of 0.75 g/L;

s03, adding the calcium hydroxide solution obtained in the step S01 into a polyacrylic acid solution, controlling the temperature system to be 85 ℃, and stirring and mixing for 40min to obtain a mixed solution;

and S04, introducing carbon dioxide gas at the bottom of the mixed solution, controlling the flow rate of the introduced gas to be 0.1L/min, stirring at the same time, wherein the stirring speed is 150rpm, stopping introducing the carbon dioxide gas when the pH value of the detection system reaches 7, and filtering, washing and drying to obtain the synthetic calcium carbonate.

Preparation example 2

A synthetic calcium carbonate, comprising the steps of:

s01, weighing 12kg of calcium oxide by weight, adding distilled water, controlling the temperature system to be 60 ℃, and stirring for dissolving to obtain a calcium hydroxide solution with the mass concentration of 0.1 mol/L;

s02, weighing 2kg of polyacrylic acid in parts by weight, then adding distilled water, controlling the temperature system to be 95 ℃, and stirring for dissolving to obtain a polyacrylic acid solution with the concentration of 0.75 g/L;

s03, adding the calcium hydroxide solution obtained in the step S01 into a polyacrylic acid solution, controlling the temperature system to be 95 ℃, and stirring and mixing for 30min to obtain a mixed solution;

and S04, introducing carbon dioxide gas at the bottom of the mixed solution, controlling the flow rate of the introduced gas to be 0.1L/min, simultaneously stirring at the stirring speed of 300rpm, stopping introducing the carbon dioxide gas when the pH value of the detection system reaches 7, filtering, washing and drying to obtain the synthetic calcium carbonate.

Preparation example 3

A synthetic calcium carbonate, comprising the steps of:

Examples

A high permeability cast film made by the steps of:

s1, mixing polyethylene, methanol, propylene-ethylene copolymer, silicon dioxide, calcium carbonate, heat stabilizer, reinforcing agent and coupling agent, adding into an internal mixer for kneading and banburying, wherein banburying temperature and banburying time refer to Table 2;

s2, extruding and granulating the product obtained in the step S1 by using a double-screw extruder, wherein the rotating speed and the extrusion temperature of the extruder refer to Table 2;

s3, preparing the plastic particles obtained in the step S2 into a film by adopting a casting method, wherein the film-making temperature refers to the table 2, and then the cast film is subjected to unidirectional stretching, and the stretching temperature, the stretching speed and the stretching and shaping time refer to the table 2;

and S4, passing the casting film prepared in the step S3 through a steam hot water tank, keeping the residence time according to the table 2, dissolving the methanol in the film, and drying to obtain the high-permeability casting film.

Examples 1 to 3

Different raw material weights and different process parameters for examples 1-3 are shown in table 2:

TABLE 2 weight of raw materials and Process parameters for examples 1-3

Wherein, in the examples 1 to 3, the inorganic filler is prepared by mixing silica and calcium carbonate according to a mass ratio of 1:3, and the particle size of the silicon dioxide is 2-5 mu m.

Example 4

A high-permeability casting film is different from that of example 1 in that a heat stabilizer is formed by mixing calcium stearate and epoxy linseed oil according to a mass ratio of 3: 1.

Example 5

A high-permeability casting film is different from that of example 1 in that a heat stabilizer is formed by mixing calcium stearate and epoxy linseed oil according to a mass ratio of 1: 1.

Example 6

A high-permeability casting film is different from that of example 1 in that a heat stabilizer is formed by mixing calcium stearate and epoxy linseed oil according to a mass ratio of 2: 1.

Example 7

A highly breathable cast film differing from example 1 in that the calcium carbonate used was the synthetic calcium carbonate obtained in preparation example 1.

Example 8

A high permeability cast film was distinguished from example 1 in that the synthetic calcium carbonate obtained in preparation example 2 was used as calcium carbonate.

Example 9

A high permeability cast film was distinguished from example 1 in that the synthetic calcium carbonate obtained in production example 3 was used as calcium carbonate.

Example 10

A highly breathable cast film, which is different from example 1 in that, initially in step S1, silica and calcium carbonate were washed with methanol in advance for 3 times in succession and then charged into an internal mixer after drying.

Example 11

A high permeability cast film made by the steps of:

s1, washing the inorganic filler with methanol for 3 times, drying, mixing 85kg of polyethylene, 13kg of methanol, 46kg of propylene-ethylene copolymer, washed 95kg of inorganic filler, washed 1.5kg of heat stabilizer, washed 0.5kg of coumarone resin and washed 1.2kg of KH792, adding the mixture into an internal mixer, kneading and banburying, wherein the banburying temperature is 150 ℃, and the banburying time is 10 min;

s2, extruding and granulating the product obtained in the step S1 by using a double-screw extruder, wherein the rotating speed of the extruder is 200rpm, and the temperature is 160 ℃;

s3, preparing the plastic particles obtained in the step S2 into a film by adopting a tape casting method, wherein the film making temperature is 200 ℃, and then performing unidirectional stretching on the tape-cast film, wherein the stretching temperature is 70 ℃, the stretching speed is 100mm/min, and the stretching setting is 30 min;

s4, enabling the casting film prepared in the step S3 to pass through a steam hot water tank, staying for 8min, dissolving methanol in the film, and drying to obtain the high-permeability casting film;

wherein the heat stabilizer is formed by mixing calcium stearate and epoxy linseed oil according to the mass ratio of 3:1, the inorganic filler is formed by mixing silicon dioxide and synthetic calcium carbonate according to the mass ratio of 1:3, the particle size of the silicon dioxide is 2-5 mu m, and the synthetic calcium carbonate is the synthetic calcium carbonate obtained in the preparation example 3.

Comparative example

Comparative example 1

A high permeability cast film differs from example 1 in that methanol in the cast film stock composition is replaced with polyethylene.

Comparative example 2

A highly breathable cast film differs from example 1 in that the coumarone resin in the cast film stock composition is replaced with polyethylene.

Comparative example 3

Chinese patent application publication No. CN110183768A discloses a high-smoothness master batch for cast films, a preparation method thereof and a high-smoothness cast film.

Performance test

The water vapor transmission rates (g/m) of examples 1 to 11 and comparative examples 1 to 2 were measured by GB/T1037-1988 test method for Water vapor permeability of Plastic films and sheets²·24h)；

The tensile strengths (MPa) of examples 1 to 11 and comparative examples 1 to 2 were measured by GB13022-1991, test method for tensile Properties of Plastic films;

GB/T10004 'test method for puncture strength of packaging plastic composite films' is adopted to test the puncture resistance of examples 1-11 and comparative examples 1-2.

TABLE 3 summary of test data for examples 1-11 and comparative examples 1-2

According to the comparison of the detection data of the example 1 and the comparative example 1 in the table 3, the methanol is added into the raw material components of the casting film, the surface tension of the methanol is small, the methanol can replace the water adsorbed on the surfaces of the inorganic filler particles during mixing, the hydrogen bond effect among the inorganic particles is reduced, the capillary force for the coalescence of the inorganic filler particles is reduced, the influence of the inorganic filler particles on the performance of the inorganic filler particles due to agglomeration is avoided, and meanwhile, the methanol is dissolved in water during passing through a steam hot water tank, so that micropores with air permeability and water resistance are formed on the casting film, the water vapor transmission rate of the casting film is improved, and the air permeability is improved.

As can be seen from comparison of the test data of example 1 and comparative example 2 in table 3, by adding the coumarone resin to the raw material components of the cast film, which has a reinforcing effect on the cast film, the tensile strength and puncture resistance of the cast film can be improved, thereby improving the mechanical properties.

As can be seen from comparison of the test data of examples 1 and 7 to 9 in Table 3, the water vapor transmission rate, tensile strength and puncture resistance of the cast film can be improved by adding the synthetic calcium carbonate. Polyacrylic acid is used as an organic matrix, the relative growth rates of different crystal faces are changed, the purpose of controlling the crystal morphology is achieved, the synthesized calcium carbonate has a special morphology, the self-performance of the calcium carbonate is changed, and the air permeability and the mechanical performance of the casting film are obviously improved.

As can be seen from comparison of the test data of examples 1 and 10 in table 3, when the silica and the calcium carbonate were previously washed with methanol, the water vapor transmission rate, the tensile strength and the puncture resistance of the cast film were improved, the surface tension of methanol was low, water molecules adsorbed on the surfaces of the silica and the calcium carbonate could be replaced, and the agglomeration of particles was reduced, thereby improving the properties of the silica and the calcium carbonate themselves and the air permeability and the mechanical properties of the cast film.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. The high-permeability cast film is characterized by being prepared from the following raw materials in parts by weight:

polyethylene: 85-110 parts;

methanol: 13-18 parts;

propylene-ethylene copolymer: 35-46 parts;

inorganic filler: 75-95 parts;

reinforcing agent: 0.5 to 1.8 portions;

coupling agent: 0.8 to 1.6 portions;

heat stabilizer resistance: 1.5-2.3 parts;

2. A highly breathable cast film according to claim 1, wherein said calcium carbonate is synthetic calcium carbonate, and said synthetic calcium carbonate is prepared by a method comprising the steps of:

3. The casting film with high air permeability as claimed in claim 1, wherein the heat stabilizer is a mixture of calcium stearate and epoxidized linseed oil in a mass ratio of 3: 1.

4. A high permeability cast film according to claim 1, wherein the coupling agent is one or a mixture of KH792, KH560 or a-172.

5. The cast film with high air permeability as claimed in claim 1, wherein the reinforcing agent is one or more of lignin, carbon black and coumarone resin.

6. A highly gas permeable cast film according to claim 1, wherein said silica has a particle size of 2 μm to 5 μm.

7. The cast film with high air permeability as claimed in claim 1, wherein the cast film is made from raw materials comprising the following parts by weight:

polyethylene: 85 parts of a mixture;

methanol: 13 parts;

propylene-ethylene copolymer: 46 parts of (a);

inorganic filler: 95 parts of (C);

coumarone resin: 0.5 part;

KH 792: 1.2 parts;

heat stabilizer resistance: 1.5 parts;

8. A method for producing a cast film with high gas permeability based on the cast film with high gas permeability according to any one of claims 1 to 8, comprising the steps of:

9. The method of claim 8, wherein the silica and the calcium carbonate are washed with methanol in advance at the beginning of the step S1 for 3 times in succession, and then dried and charged into the internal mixer.