CN109735040B

CN109735040B - Super-hydrophobic anti-fog master batch for thin film and preparation thereof

Info

Publication number: CN109735040B
Application number: CN201811414976.8A
Authority: CN
Inventors: 王锦江; 刘小珊; 周慕纯; 张冬梅
Original assignee: Shantou Best Science And Technology Co ltd
Current assignee: Shantou Best Science And Technology Co ltd
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2021-02-09
Anticipated expiration: 2038-11-26
Also published as: CN109735040A

Abstract

The invention relates to a super-hydrophobic anti-fog master batch for a polypropylene film and a preparation method thereof. The method mainly comprises the following steps: (1) preparing grafted polypropylene PP-g-GMA by a melt grafting method; (2) copolymerizing ethylaminosiloxane and methyl hydrosiloxane; (3) reacting the ethyl aminosiloxane/methyl hydrogen-containing siloxane copolymer obtained in the step (2) with perfluorooctylethylene to prepare fluorosilicone resin with amino; (4) and (3) reactively extruding the fluorosilicone resin with amino groups obtained in the step (3) with the grafted polypropylene PP-g-GMA and the polypropylene obtained in the step (1), and reacting the amino groups on the fluorosilicone resin with amino groups with epoxy groups on the side chains of the grafted polypropylene PP-g-GMA to prepare the super-hydrophobic antifogging master batch. The hydrophobic anti-fog master batch is added to the anti-fog surface layer of the film and mixed to prepare the anti-fog film, and the anti-fog film has the advantages of easiness in processing, low cost, good anti-fog effect, permanent anti-fog property, no influence on the optical performance of the film, improvement on the weather resistance of the polyolefin film and the like. Can be applied to vegetable preservation.

Description

Super-hydrophobic anti-fog master batch for thin film and preparation thereof

Technical Field

The invention relates to the field of super-hydrophobic anti-fog master batches, in particular to a super-hydrophobic anti-fog master batch for a film and a preparation method thereof.

Background

The antifogging film is mainly applied to the fields of agricultural films and food packaging, for example, the antifogging agricultural film can prevent fog drops from reducing the light transmittance of a greenhouse and directly influencing the growth of crops, and the fog drops can cause the rot of stems and leaves when falling on the crops. Currently, the antifogging films are mainly biaxially oriented polypropylene films (BOPP), cast polypropylene films (CPP), cast polyethylene films (CPE). Polyethylene and polypropylene are both nonpolar polymers, the hydrophilicity is poor, the surface tension of the polyethylene and the polypropylene is low and is only 31mN/m, the surface tension of water is 72mN/m, the contact angle of pure polyethylene and polypropylene films to water is 90-92 degrees, and the antifogging effect cannot be achieved.

At present, an antifogging film achieves the aim of antifogging mainly by forming a super-hydrophilic layer on the surface of the film. There are generally two techniques: the outer coating method is characterized in that a coating with an antifogging agent is coated on the surface of a film, and the surface layer of the film is made to have hydrophilicity through the processes of solvent volatilization and the like; and the other is an internal addition method, wherein the antifogging agent is prepared into antifogging master batch, and the antifogging master batch is added into the film core layer and the antifogging layer for mixing to prepare the antifogging film. The antifogging agent adopted by the internal addition method is usually a micromolecular hydrophilic substance with mobility, and the micromolecular antifogging agent is migrated to the surface layer of the film in the film to change the wettability of the surface, so that the condensed moisture on the surface layer of the film is in a uniform wetting state, a continuous phase is formed and is not condensed into water drops or dew, and the antifogging effect is achieved.

The patent: an antistatic antifogging mother material and its production process (201110239258.3) are disclosed, which features that it can both antistatic and antifogging. The composition comprises the following components in parts by weight: 55-65 parts of polypropylene; 1-5 parts of glass beads; 15-20 parts of an anti-sticking agent; 20-25 parts of a dispersing agent; 10-15 parts of antistatic agent. And (3) preparing materials by using a precise weighing system, fully mixing, extruding the melt by using a double-screw extruder, drying, cooling and granulating the extruded melt to obtain a finished master batch.

The patent: a novel optical antifogging film and a preparation method (201010528345.6) thereof provide the optical antifogging film with firm adhesion and good antifogging effect, and the preparation method and the application thereof, wherein the novel optical antifogging film is prepared by alternately coating films in acrylic acid and cationic polyacrylamide-sodium silicate solution and drying. The invention has good adhesiveness, light transmission and antifogging property.

The patent: a long-acting weather-resistant non-drip fog dispersal greenhouse film and a preparation method (201510337053.7) thereof relate to a long-acting weather-resistant non-drip fog dispersal greenhouse film and a preparation method thereof, and belong to the field of high polymer materials. The long-acting weather-proof dripless fog dispersal greenhouse film comprises an inner layer, a middle layer and an outer layer; wherein, the inner layer is made of metallocene linear low density polyethylene, linear low density polyethylene and antifogging master batch; the middle layer is made of high-pressure polyethylene and heat-insulating master batch; the outer layer is made of metallocene linear low density polyethylene, linear low density polyethylene and uvioresistant mother material. The greenhouse film has good long-term non-drop fog dissipation effect, excellent transparency, puncture resistance, weather resistance and long service life; the preparation method of the invention has simple process and is easy to realize.

The main disadvantages of the external coating method are that coating facilities need to be added, the problems of solvent volatilization, recovery, environmental pollution and the like exist, and the antifogging effect is often influenced due to the fact that the coating is not firm. The main disadvantage of the internal addition method is that the antifogging agent is hydrophilic micromolecule, and the antifogging effect is achieved by the migration of the micromolecule to the surface layer of the film, and the antifogging effect is related to the migration amount of the micromolecule. Because the small molecules of the antifogging agent can be dissolved in water, the antifogging agent in the film is gradually lost due to frequent contact with water, and the antifogging effect is gradually weakened. Moreover, because the migration of the micromolecules of the antifogging agent is influenced by temperature, when the temperature is too low, the migration amount of the micromolecules is too small, the antifogging effect is too poor, the temperature is too high, and the loss of the antifogging agent is more.

Disclosure of Invention

The invention aims to provide a super-hydrophobic antifogging agent for a film and a preparation method thereof, and solves the problems in the prior art.

A preparation method of a super-hydrophobic anti-fog master batch for a film mainly comprises the following steps:

(1) preparing grafted polypropylene PP-g-GMA by a melt grafting method;

(2) copolymerizing ethylaminosiloxane and methyl hydrosiloxane;

(3) reacting the ethyl aminosiloxane/methyl hydrogen-containing siloxane copolymer obtained in the step (2) with perfluorooctylethylene to prepare fluorosilicone resin with amino;

(4) and (3) reactively extruding the fluorosilicone resin with amino groups obtained in the step (3), the grafted polypropylene PP-g-GMA and the polypropylene obtained in the step (1), and reacting the amino groups on the fluorosilicone resin with amino groups with epoxy groups on the side chains of the grafted polypropylene PP-g-GMA to prepare the super-hydrophobic antifogging master batch containing the graft copolymer of the polypropylene-fluorosilicone resin.

According to the invention, nonpolar polypropylene is grafted with GMA, polar epoxy groups are introduced into polypropylene side chains, and the fluorine-silicon resin with amino groups is grafted onto the polypropylene side chains through the reaction of the amino groups on the fluorine-silicon resin and the epoxy groups on the grafted polypropylene side chains, so as to prepare the polypropylene-fluorine-silicon resin graft copolymer. Compared with the common PP-g-GMA in the market, the grafted polypropylene PP-g-GMA prepared by the invention has the advantages that the polypropylene suitable for the ultra-transparent film is used as the main material, so that the transparency is better; secondly, the grafting rate is controllable, the grafted polypropylene has higher reaction activity, and the reaction with the fluorosilicone resin is facilitated in the next step; thirdly, the processing convenience.

The fluorosilicone resin disclosed by the invention takes silicon oxide as a main chain, and the soft main chain structure endows the fluorosilicone resin with good high elasticity and rheological property; the side chain introduces high-content fluorine-containing groups, so that the effects of fluorine and silicon synergistic anti-fouling and anti-fogging are achieved; the amino side group is introduced into the main chain, and the amino group can react with the epoxy group on the grafted polypropylene to obtain the fluorosilicone resin-polypropylene graft copolymer. The fluorosilicone resin has improved weather resistance, and fluorine can improve weather resistance.

The preparation of the fluorosilicone resin comprises the steps of introducing perfluorooctylethylene into an ethyl aminosiloxane/methyl hydrogen-containing siloxane copolymer, wherein the siloxane main chain endows the copolymer with high elasticity and fluidity, introducing a high-content fluorine-containing group into a side chain, and endowing the fluorosilicone with good anti-fouling, anti-fog, self-cleaning capability, temperature resistance and weather resistance by the synergistic effect of the fluorosilicone.

The fluorosilicone resin has extremely low surface energy and has the characteristics of hydrophobicity and oleophobicity. The contact angle of the surface of the film is increased by using the fluorosilicone resin, and when the water contact angle of the surface of the film is more than 150 degrees and the rolling angle is less than 10 degrees, the excellent superhydrophobic performance of the surface can prevent fog drops from being adhered and polymerized on the surface of a solid, so that the fog prevention is realized.

Further, the preparation of the grafted polypropylene PP-g-GMA by the melt grafting method in the step (1) mainly comprises the following steps: polypropylene (PP) is used as a carrier, Glycidyl Methacrylate (GMA) is used as a grafting monomer, dicumyl peroxide (DCP) is used as an initiator, and the PP, the DCP and the GMA are blended and then enter an extruder from a feeding port for melt extrusion. In the extrusion melting process, DCP forms micromolecular free radicals at high temperature to attack tertiary carbon on a PP main chain to form macromolecular free radicals, the macromolecular free radicals react with double bonds of GMA molecules to form grafted polypropylene PP-g-GMA, and the prepared grafted polypropylene PP-g-GMA is granulated and dried.

The chemical reaction scheme for GMA grafting PP is shown below, wherein the long chain represents a PP molecular chain.

Further, the polypropylene: glycidyl methacrylate: the dicumyl peroxide is used in the ratio of 100:10:1, the melt grafting temperature is 140-180 ℃, and the grafting rate is 8%.

Further, the polypropylene is prepared by mixing random polypropylene: syndiotactic polypropylene: the isotactic polypropylene is blended in a ratio of 1:1: 2. The method adopts powdery PP, the atactic PP is an amorphous polymer, the syndiotactic PP is a low-crystallinity polymer, the isotactic degree of the atactic PP and the syndiotactic PP is low, the melting point is low, the melt viscosity is low, the grafting reaction is more suitable, and the proper melt strength is ensured by adding the isotactic PP. The powder is added once for melt grafting, so that the grafting efficiency is higher. Compared with secondary feeding, the addition of random and syndiotactic PP greatly reduces torque, is beneficial to improving rotating speed and grafting efficiency, and the viscosity of PP melt is not changed greatly and is not degraded obviously.

Further, the fluorine-silicon resin with amino and the grafted polypropylene PP-g-GMA are prepared according to the proportion of 1: 5 in a ratio of 5. Firstly on account of the fact that the grafting yield of the grafted polypropylene is not a hundred percent and secondly on account of the ease of processing.

Further, the fluorosilicone resin with amino is blended with the grafted polypropylene PP-g-GMA, then the materials are fed from a main feeding material, the materials enter into melt reactive co-extrusion, and the polypropylene is fed in from a side feeding material.

The method has two purposes of dividing into main feeding and side feeding and separate feeding, wherein the first purpose is to accurately control materials; the second purpose is to make the grafted polypropylene and the amino-bearing material react to obtain the polypropylene-fluorosilicone copolymer, and a distance is arranged between the main feeding port and the measuring feeding port.

The purpose of adding polypropylene is to reduce the content of the fluorosilicone resin, the content of the fluorosilicone resin in the master batch is not good when the content is too low and too high, the master batch needs to be added too high when the content is too low, the use cost of customers is too high, and the mixing is not uniform; too high amount of the anti-fog master batch causes poor processing, and too low amount of the master batch is easy to cause uneven distribution of the fluorosilicone resin in the film.

Further, the polypropylene is homo-polypropylene or co-polypropylene, and the ratio of a blend formed by the polypropylene, the amino-containing fluorosilicone resin and the grafted polypropylene PP-g-GMA is 3: 2. The proportion takes the proportion of the fluorosilicone resin in the total content into consideration, the proportion of the fluorosilicone resin in the master batch accounts for 10%, and the proportion of the main feeding materials and the side feeding materials in the process is taken into consideration, so that a good blending effect is achieved.

The super-hydrophobic antifogging agent for the film prepared by the preparation method.

The super-hydrophobic antifogging agent for the film is applied to vegetable preservation.

The invention has the beneficial effects that: firstly, the fluorosilicone resin takes a silicon-oxygen bond as a main chain, a high-content fluorine-containing group is introduced into a side chain, so that the fluorine-silicon synergistic anti-fouling and anti-fogging effect is achieved, the contact angle of the surface of the film is larger than 150 degrees due to extremely low surface energy and super hydrophobicity, and a very small rolling angle is provided, so that the fog drops are prevented from being adhered and polymerized on the surface of the film; the silicon-oxygen bond is long, has unique inherent conformation flexibility, has good high elasticity and rheological property due to the soft main chain structure, can reach 422.5 kJ.mol, and has high and low temperature resistance; the bond length of the carbon-fluorine bond is extremely short, the bond energy is up to 486kJ & mol, and the bond is difficult to be damaged by heat, light and chemical factors, so that the fluorine-silicon resin has excellent thermal stability, chemical resistance and weather resistance, and can improve the thermal stability, weather resistance and environmental stress resistance of polypropylene; introducing amino side groups on the main chain, wherein the amino groups can react with epoxy groups on the grafted polypropylene to obtain a fluorosilicone resin-polypropylene graft copolymer; the hydrophobic antifogging master batch is added to the antifogging surface layer of the film to prepare the antifogging film through mixing, the processing efficiency is high, the cost is low, the antifogging effect is good, the permanent antifogging effect is realized, the optical performance of the film is not influenced, the weather resistance of the polyolefin film is improved, and the like, and the method can be applied to vegetable preservation.

Drawings

FIG. 1 is a comparison graph of antifogging effect of cold fog test;

FIG. 2 is a graph showing the antifogging effect of the type (b) film after heat treatment;

FIG. 3 is a comparison graph of antifogging effect of the hot fog test;

FIG. 4 is a graph comparing the antifogging effect of the film after heat treatment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

Example 1

the first step is as follows: preparation of grafted Polypropylene PP-g-GMA by melt grafting:

polypropylene (PP) is used as a carrier, Glycidyl Methacrylate (GMA) is used as a grafting monomer, dicumyl peroxide (DCP) is used as an initiator, and the PP, the DCP and the GMA are blended and then enter an extruder from a feeding port for melt extrusion. In the extrusion melting process, DCP forms micromolecular free radicals at high temperature to attack tertiary carbon on a PP main chain to form macromolecular free radicals, the macromolecular free radicals react with double bonds of GMA molecules to form grafted polypropylene PP-g-GMA, and the prepared grafted polypropylene PP-g-GMA is granulated and dried.

PP: GMA: DCP ratio 100:10:1, PP: GMA: the proportion of DCP is 100:10:1, the melt grafting temperature is 140-180 ℃, and the grafting rate is 8%. The PP used was as random: and (3) syndiotactic: blending according to the ratio of 1:1:2, and adopting powdery PP.

The second step is that: preparation of super-hydrophobic antifogging agent fluorine-silicon resin-polypropylene graft copolymer

Mixing fluorosilicone resin and grafted polypropylene PP-g-GMA according to the proportion of 1: 5, feeding materials from a main feeding material, performing melt reactive co-extrusion, and adding PP (polypropylene) at a side feeding material, wherein the PP can be homopolymerized PP or copolymerized PP, and the ratio of PP: the blend ratio was 3: 2.

The fluorosilicone resin was prepared as follows:

copolymerizing ethyl amino siloxane and methyl hydrogen-containing siloxane;

and reacting active hydrogen on the ethyl amino siloxane/methyl hydrogen-containing siloxane copolymer with perfluorooctyl ethylene to prepare the fluorosilicone resin.

Example 2

The film prepared in example 1 was subjected to a performance test using a superhydrophobic antifogging master batch.

(1) Comparison of antifogging effect in cold fog test

Different antifogging master batches are added to prepare the antifogging film, the antifogging film is prepared by adopting a tape casting method, the thickness of the BOPP antifogging film is 28 micrometers, the thickness of two surface layers is 2 micrometers, the thickness of a core layer is 24 micrometers, hot fog and cold fog tests are carried out, and the antifogging effect is compared.

According to the national standard GB/T31726-2015 antifogging test method for plastic films, antifogging performance tests are carried out on the three types of films, and the antifogging performance of the films under cold and hot conditions is tested by adopting a 6.1 cold fog method and a 6.3 water-bath hot fog method.

According to the cold fogging method test method, 200mL of purified water is injected into a plain beaker, the film is fixed by a rubber band, the film is placed in a refrigerated cabinet at the temperature of 2-5 ℃, the film is taken out after being placed for 5min, the antifogging effect of the film is observed on a standard logarithmic visual chart, and the antifogging effect comparison graph of the three types of films is shown in figure 1. According to the test registration judgment of national standards, the (a) type film is completely transparent and has no water drops, the visual chart is completely clear, the grade is the highest grade 1, and the antifogging effect is excellent; (b) the similar film is basically transparent, has more water drops, and the visual chart font is deformed, the grade is 3, and the antifogging effect is general; (c) the similar film is semitransparent, has a plurality of water drops, is visible in a small amount below 0.1 of a visual chart, is graded as 4, and has poor antifogging effect.

After the film of type (b) was placed in a thermostat and heat-treated (60 + -2 deg.C) for 3 hours, the cold fog method test was carried out, and the result is shown in FIG. 2, wherein the area of the film above 95% was transparent, only a few large water drops were gathered, and the antifogging grade 2 (better transparency, a few uneven large water drops, more than 50% clarity of visual chart) was judged according to the national standard. The fact that when the temperature is lower, the antifogging agent of the film of the type (b) migrates slower, so that the antifogging effect is weakened, and after heat treatment, enough antifogging agent migrates to the surface of the film to achieve good antifogging effect.

(2) Comparison of antifogging effect in hot fog test

Tap water is added into a constant-temperature water tank, the temperature of the water tank is 59-61 ℃, 200mL of purified water is injected into a bottle mouth beaker, the film is fixed by a rubber band, the bottom of the cup is immersed into a water bath for 5cm, the antifogging effect of the film is observed after 15min, and the antifogging effect comparison graph of the three types of films is shown in figure 3. According to the test registration judgment of national standards, the (a) type film is completely transparent and has no water drops, the visual chart is completely clear, the grade is the highest grade 1, and the antifogging effect is excellent; (b) the similar film is completely transparent, has no water drops, is completely clear in an eye chart, has the highest grade of 1, and has excellent anti-fog effect; the film of type (c) has many water drops, is completely opaque, is completely unclear on a visual chart, is 5 in grade, and has poor antifogging effect.

(3) Cold fog-proof contrast diagram of (a) type and (b) type films after heat treatment

The film is prepared from the super-hydrophobic anti-fog master batch (a) and the organic micromolecular anti-fog master batch (b). Placing the film (a) and the film (b) in a constant temperature box, and carrying out constant temperature treatment at the temperature of 60 +/-2 ℃ for 24h (migration and excessive consumption of the organic antifogging agent to cause antifogging failure). (b) White powder is precipitated on the surface of the film after heat treatment, the film (a) has no obvious change, and the powder on the surface of the film (b) is removed. After treatment, the test is carried out by a cold fog method according to national standards, and the test time is prolonged. As can be seen from the comparison graph of the antifogging effect of the film after the heat treatment in fig. 4, the antifogging effect of the film of (a) class is always good, and the antifogging effect of the film of (b) class is good after the heat treatment for a period of time due to the migration and consumption of the micromolecular antifogging agent, but the antifogging effect gradually weakens after the surface antifogging agent is taken away by water drops, and finally the antifogging effect is caused to lose efficacy.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a super-hydrophobic anti-fog master batch for a film is characterized by mainly comprising the following steps:

(1) preparing grafted polypropylene PP-g-GMA by a melt grafting method;

(2) copolymerizing ethylaminodimethoxysilane and methyldimethoxysilane;

(3) reacting the ethyl amino dimethoxy silane/methyl dimethoxy hydrosilane copolymer obtained in the step (2) with perfluorooctyl ethylene to prepare fluorosilicone resin with amino;

(4) and (3) reactively extruding the fluorosilicone resin with amino groups obtained in the step (3) with the grafted polypropylene PP-g-GMA and the polypropylene obtained in the step (1), and reacting the amino groups on the fluorosilicone resin with amino groups with epoxy groups on the side chains of the grafted polypropylene PP-g-GMA to prepare the super-hydrophobic antifogging master batch containing the graft copolymer of the polypropylene-fluorosilicone resin.

2. The preparation method according to claim 1, wherein the step (1) of preparing the grafted polypropylene PP-g-GMA by using the melt grafting method mainly comprises the following steps: polypropylene is taken as a carrier, glycidyl methacrylate is taken as a grafting monomer, dicumyl peroxide is taken as an initiator, the polypropylene is taken as a carrier, the glycidyl methacrylate and the dicumyl peroxide are mixed and then enter an extruder from a feeding port for melt extrusion, and the prepared grafted polypropylene PP-g-GMA is granulated and dried.

3. The production method according to claim 2, wherein the ratio of the polypropylene: glycidyl methacrylate: the proportion of dicumyl peroxide is 100:10:1, and the melt grafting temperature is 140-180 ℃.

4. The process according to claim 3, wherein the polypropylene is prepared as random polypropylene: syndiotactic polypropylene: the isotactic polypropylene is blended in a ratio of 1:1: 2.

5. The preparation method according to claim 1, wherein the amino group-containing fluorosilicone resin and the grafted polypropylene PP-g-GMA are prepared in a ratio of 1: 5 in a ratio of 5.

6. The preparation method of claim 5, wherein the amino group-containing fluorosilicone resin is blended with the grafted polypropylene PP-g-GMA, and then the blend is fed from a main feed, melt reactive coextrusion is carried out, and polypropylene is fed from a side feed.

7. The preparation method according to claim 6, wherein the polypropylene is homo-polypropylene or co-polypropylene, and the blend ratio of the polypropylene and the amino group-containing fluorosilicone resin to the grafted polypropylene PP-g-GMA is 3: 2.

8. A super-hydrophobic anti-fog master batch for a film prepared according to the preparation method of any one of claims 1 to 7.

9. The use of the super-hydrophobic anti-fog master batch for the film according to claim 8 is characterized by being used for keeping vegetables fresh.