CN114539580B

CN114539580B - Milk-free cover film and preparation method thereof

Info

Publication number: CN114539580B
Application number: CN202011330722.5A
Authority: CN
Inventors: 崇政; 盛佳; 王震业; 王凤凯; 侯英梁
Original assignee: Inner Mongolia Mengniu Dairy Group Co Ltd
Current assignee: Inner Mongolia Mengniu Dairy Group Co Ltd
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2023-08-29
Anticipated expiration: 2040-11-24
Also published as: CN114539580A

Abstract

A non-milk-sticky cover film and a preparation method thereof, wherein the non-milk-sticky cover film is provided with a non-milk-sticky coating on the inner layer of the cover film, and the load capacity of the non-milk-sticky coating on the cover film is 0.62-0.84g/m ² The method comprises the steps of carrying out a first treatment on the surface of the The raw materials of the non-milk-sticky coating comprise solid particles, hydrophobic silane, a pH regulator and a solvent; the mass ratio of the solid particles to the hydrophobic silane is (1.5-6): 1, a step of; the solid particles are less than 15% of the total amount of the raw materials, and the pH value of the raw materials is 6.8-7.2. The invention not only can improve the anti-adhesion effect in the high-viscosity product, but also can obviously prolong the anti-adhesion time in the high-viscosity product, and can avoid the failure of the non-stick effect within 3 months.

Description

Milk-free cover film and preparation method thereof

Technical Field

The invention relates to the field of packaging, in particular to a milk-free cover film and a preparation method thereof.

Background

Yogurt is a daily milk drink, and in terms of its quality, in addition to the quality of the milk itself, there is also a certain requirement for its packaging itself, which, because of being a food packaging, is related to its safety and stability.

Generally, the yogurt is relatively sticky, and the yogurt is adhered to the inner layer of the cover film when the yogurt is eaten daily. When the yogurt is eaten, the cover film needs to be torn, at the moment, the yogurt adhered to the inner layer of the cover film is easy to be polluted by hands, and if the yogurt is licked by the tongue, the yogurt adhered to the inner layer of the cover film is not sanitary and unsightly, so that the yogurt is usually thrown away to cause waste. Especially, the yogurt with higher viscosity, along with the increase of viscosity, the amount of yogurt attached to the inner layer of the cover film is gradually increased, so that the inconvenience and waste of eating are increased to a certain extent.

In order to solve the problem of yogurt adhesion, a non-sticking yogurt cover film is disclosed in Chinese patent document CN108190235A, a layer of coating is additionally arranged, and the effect of preventing yogurt from adhering to the cover film is achieved by utilizing the special properties of the coating. The coating is made of polyurethane compounds and has a concave particle and convex particle structure, so that the problem of adhesion of yoghourt is relieved by utilizing the concave particle structure. However, with the increase of the types of yogurt, especially the appearance of high-viscosity yogurt containing thick seasonings such as jam and honey in the market, the anti-adhesion effect of the coating is obviously weakened due to the increase of the viscosity, and the above technology cannot meet the anti-adhesion requirement of the high-viscosity yogurt.

In order to further enhance the adhesion preventing performance of the cap film, for example, chinese patent document CN105835452a discloses a cap material which is also provided with a structure of concave particles and convex particles, and more importantly, an adhesion preventing layer having hydrophobic performance is further provided on the surface layer of the concave particles and convex particles, the adhesion preventing layer is composed of hydrophobic particles and a binder, the hydrophobic particles are inorganic oxides, preferably silica, and the binder is preferably a metal alkoxide. The anti-adhesion layer can improve the anti-adhesion effect to a certain extent, but still cannot meet the anti-adhesion requirement of the high-viscosity yoghurt.

In addition, along with the continuous updating and changing of the requirements of the yoghourt, normal-temperature yoghourt with the shelf life of 3 months is continuously appeared on the market, and for the yoghourt, due to long-term storage, the anti-adhesion layer on the cover film has certain loss, and the adhesion problem in the shelf life cannot be solved by adopting the arrangement of the anti-adhesion layer disclosed in the prior art.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defect that the adhesion of the high-viscosity yoghurt cannot be prevented for a long time when the adhesion preventing layer in the prior art is applied to the high-viscosity yoghurt, so that the milk-free cover film capable of preventing the adhesion of the high-viscosity yoghurt to the cover film can be still maintained within 3 months, and the preparation method thereof are provided.

A non-milk-sticky cover film, wherein a non-milk-sticky coating is arranged on the inner layer of the cover film; the load capacity of the hydrophobic coating liquid non-milk-sticky coating on the cover film is 0.62-0.84g/m ² ；

The raw materials of the non-milk-sticky coating comprise solid particles, hydrophobic silane, a pH regulator and a solvent; the mass ratio of the solid particles to the hydrophobic silane is (1.5-6): 1, a step of; the solid particles are less than 15% of the total amount of the raw materials, and the pH value of the raw materials is 6.8-7.2.

The solid particles are at least one of silicon dioxide, zinc oxide, titanium dioxide and calcium carbonate. The particle size of the solid particles is between 500nm and 2000 nm.

The hydrophobic silane is at least one of aminopropyl triethoxysilane, propyl trimethoxysilane or polydimethylsiloxane.

The pH regulator is at least one of acetic acid, hydrochloric acid, sulfuric acid or citric acid.

The solvent is an alcohol substance with the mass concentration higher than 90%, and the alcohol substance is at least one of ethanol, isopropanol, n-butanol or n-hexanol.

The solid particles are 3-6% of the total amount of the raw materials.

A method for preparing a non-milk-sticky cover film comprises the steps of coating raw materials of a non-milk-sticky coating on an inner layer of the cover film, and solidifying.

The cover film is a coiled film, and the coating process is as follows: pouring the raw materials of the non-milky coating into a coating groove, and coating on a coiled film by using a coating roller.

The coating roller is an anilox roller, the specification of the net wire on the anilox roller is 120 wires, the coating times are 1-4 times, and the coating speed is 60m/min; the curing temperature is 50-100 ℃.

The preparation process of the non-milk-sticky coating comprises the following steps:

mixing solid particles with a solvent under stirring to prepare a solid particle solution;

adding a pH regulator into the solid particle solution to disperse to obtain a dispersion liquid;

dripping hydrophobic silane into the dispersion liquid according to the condition of 10-20g/min, and stirring for at least 2 hours after the dripping is finished;

oscillating with ultrasonic wave for at least 30 min;

preferably, the stirring condition is 500-1000 r/min; the oscillation temperature is lower than 35 ℃;

preferably, the water bath is used for controlling the oscillation temperature, and the water replacement frequency of the water bath is once every 15min in the oscillation process.

The technical scheme of the invention has the following advantages:

the invention provides a non-milk-sticky cover film, which is formed by specifically selecting specific compound coating liquid of solid particles, hydrophobic silane, pH value regulator and solvent, and particularly limiting the addition ratio between the solid particles and the hydrophobic silane, so that the non-milk-sticky coating can be effectively and well combined on the cover film, and the anti-adhesion effect in a high-viscosity product can be improved and the anti-adhesion time in the high-viscosity product can be remarkably prolonged through the application of the non-milk-sticky cover film; experiments prove that the mass ratio of the solid particles to the hydrophobic silane is (1.5-6): 1, solid particles are below 15% of the total amount of the raw materials, when the pH value of the raw materials is set to be 6.8-7.2, a proper amount of a plurality of bulges can be formed on the surface of the inner layer of the cover film, so that the adhesion of the yoghourt is better avoided, meanwhile, the solid particles are coated by hydrophobic silane, so that the non-sticky invalidation caused by the fact that the high-viscosity yoghourt is in contact with the coating for a long time and is trapped in gaps among the particles can be more effectively avoided, and the non-sticky invalidation time is prolonged;

in addition, the load of the non-tacky coating on the cover film is selected to be 0.62-0.84g/m ² Therefore, the anti-adhesion duration can be further prolonged to 3 months through the selection of the load, the situation that the non-adhesive effect fails in 3 months is avoided, the problem that powder drops from particles in the non-adhesive milk cover film coating can be avoided, and the effect is quite remarkable.

Detailed Description

The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.

The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge. The percentages used in the examples below are mass percentages unless otherwise indicated.

Example 1

A non-milk-sticky cover film, wherein a non-milk-sticky coating is arranged on the inner layer of the cover film; the non-milky coating is obtained after the hydrophobic coating liquid is solidified. The specific preparation method of the milk-free cover film comprises the following steps:

first, hydrophobic coating liquids of different solid contents were prepared according to the raw material compositions shown in table 1 below.

TABLE 1

Raw materials	The solid content is 3%	Solids content 4%	The solid content is 5%	The solid content is 6%
					Ethanol	67.95％	57.95％	47.95％	37.95％
Silica solution	30％	40％	50％	60％
					Polydimethylsiloxane	2％	2％	2％	2％
Acetic acid solution	0.05％	0.05％	0.05％	0.05％

The silica solution in Table 1 was a mixed solution obtained by mixing 10% by weight of silica and 90% by weight of ethanol, and the solid content of the silica solution was 10%, that is, the content of silica in the silica solution was 10%, and the particle size of the silica was 500nm to 2000 nm. Ethanol in table 1 and ethanol in the silica solution were all 99.9% absolute ethanol; the mass concentration of the acetic acid solution is 2%, and the solvent in the acetic acid solution is distilled water. That is, in this example, the solid particles were silica, the hydrophobic silane was polydimethylsiloxane, and the pH adjuster was acetic acid.

Taking a hydrophobic coating liquid with a solid content of 3% as an example, 20.385kg of ethanol with a concentration of 99.9%, 9kg of a silica solution with a solid content of 10%, 0.015kg of a 2% acetic acid solution and 0.6kg of polydimethylsiloxane.

The specific preparation method of the hydrophobic coating liquid comprises the following steps:

uniformly blending ethanol and a silicon dioxide solution for 10min by adopting a high-speed dispersing machine;

adding an acetic acid solution, and dispersing for 10min by a high-speed dispersing machine;

thirdly, adding the polydimethylsiloxane, and titrating by a peristaltic pump, wherein titration parameters are as follows: 15g/min, titration time 40min;

after the titration is finished, dispersing at a high speed for 3 hours;

fifthly, carrying out ultrasonic oscillation for 1 hour, wherein in the oscillation process, clear water is changed every 15 minutes, so that the temperature of an oscillation pool is prevented from being too high;

forming coating liquid which is not stained with milk and has different solid contents.

Then, the hydrophobic coating liquid with different solid contents prepared by adopting the process is used for coating a cover film, and the specific process is as follows: the hydrophobic coating liquid was poured into the coating tank, and the hydrophobic coating liquid was coated on the cover film roll film by running the coating roll of the wire 120 wire, coating speed: and (3) drying in four drying channels at the temperature of 60m/min, wherein the drying parameters of the four drying channels are 50-70-80-100 ℃.

The above coating process is repeated 1 to 5 times to complete the coating operation, and in the present invention, the number of coating times is the number of pass rolls, that is, 1 pass roll, which is called 1 pass coating. The present example examined the loading (g/m) of the non-stick coating on the mulch film at different coating times ² ) The loading is the weight added per square mulch film after coating is complete and drying is cured. The more the coating times are, the more the film winding times are correspondingly increased, so that the production efficiency is not facilitated, and the actual mass production possibility is hardly generated when the film is coated for more than 5 times, so that the coating times are less than 5 times in the whole test of the invention, and the coating times are preferably 1-4 times in the invention.

The loadings of the hydrophobic coating liquids with different solid contents after various times of coating are shown in table 2.

TABLE 2

Number of coating times	The solid content is 3%	Solids content 4%	The solid content is 5%	The solid content is 6%
					Coating for 2 times	0.33	0.40	0.45	0.50
Coating for 3 times	0.52	0.64	0.68	0.80
					Coating for 4 times	0.62	0.84	0.95	1.05
Coating for 5 times	0.81	1.12	/	/

The cover film prepared by the method is applied to cup-shaped yoghourt with the viscosity range of 13000-18000cps to detect the non-stick effect, and the detection method comprises the following steps: and (5) shaking the sealed milk left and right and up and down for 10 seconds, inverting for 5 seconds, standing for 5 seconds, and tearing to observe the milk dipping condition on the cover film.

It was found by examination that the concentration of the catalyst was 0.62-0.84g/m ² Can realize no sticking of 'coping with high viscosity yoghurt' and noThe powder falling phenomenon can occur, wherein the viscosity of the high-viscosity yoghourt ranges from 13000 cps to 18000cps. The non-failure in the detection result refers to that the milk dipping area is less than 20 percent, and the milk dipping area is determined to be failure when the milk dipping area is more than or equal to 20 percent.

Wherein the average particle diameter is 0.62-0.84g/m ² The effect is examined in detail, and the specific results are as follows:

the non-sticky milk cover film is obtained by coating the hydrophobic coating liquid with 3% of solid content for 4 times, and has good non-sticky effect: contact angle 150 °, roll angle 5 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by coating the hydrophobic coating liquid with 3% of solid content for 5 times, and has good non-sticky effect: contact angle 150 °, roll angle 5 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by 3 times of coating of the hydrophobic coating liquid with the solid content of 4%, and has good non-sticky effect: contact angle 150 °, roll angle 5 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by 4 times of coating of the hydrophobic coating liquid with the solid content of 4 percent, and has good non-sticky effect: contact angle 150 °, roll angle 3 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by 3 times of coating of the hydrophobic coating liquid with the solid content of 5%, and has good non-sticky effect: contact angle 150 °, roll angle 4 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by 3 times of coating of the hydrophobic coating liquid with the solid content of 6%, and has good non-sticky effect: contact angle 150 °, roll angle 3 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

At the same time, for the ratio of 0.62-0.84g/m ² The other effects were examined in detail, and the results were as follows:

the non-sticky milk cover film is obtained by coating the hydrophobic coating liquid with 3% of solid content for 2 times, and the non-sticky effect is poor: contact angle 120 °, roll angle 10 °; standing for 3 months, wherein the non-stick effect is invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by 3 times of coating of the hydrophobic coating liquid with 3 percent of solid content, and the non-sticky effect is slightly poor: contact angle 120 °, roll angle 10 °; standing for 3 months, wherein the non-stick effect is invalid; no powder falling (coating solid falling off) occurs.

The non-sticky milk cover film is obtained by coating the hydrophobic coating liquid with 6% of solid content for 4 times, and has good non-sticky effect: contact angle 150 °, roll angle 3 °; standing for 3 months, wherein the non-stick effect is invalid; and the large-area powder falling condition occurs.

Example 2

The difference between this example and example 1 is that the preparation is carried out by using raw materials with different proportions in this example, and the specific details are shown in the following table 3:

TABLE 3 Table 3

Raw materials	Solids content 4%	Solids content 4%	Solids content 4%
				Ethanol	58.92％	58.44％	57.92％
Silica solution	40％	40％	40％
				Polydimethylsiloxane	1％	1.5％	2％
Acetic acid solution	0.08％	0.06％	0.08％

The three hydrophobic coating liquids with the solid content of 4% in the table 3 are respectively coated for 3 times to obtain a non-sticky cover film, and the detection results of the non-sticky effects of the three non-sticky cover films are the same, and the effects are as follows: contact angle 150 °, roll angle 5 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

Example 3

The difference between this example and example 1 is that the preparation was carried out using different types of raw materials of the hydrophobic coating liquid in this example, as shown in table 4 below:

TABLE 4 Table 4

The solid content of the solid particle solution is 10%, namely the mass fraction of the solid particles in the solid particle solution is 10%. The solvent used in the solid particle solution is the same as the solvent described in the corresponding number, and the solvent of the pH regulator is distilled water.

The non-sticky milk cover film obtained by 3 times of coating of the hydrophobic coating liquid has good non-sticky effect, and is specifically:

the contact angle of No. 1 is 150 °, the roll angle is 3 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The contact angle numbered 2 is 150 °, the roll angle is 3 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

The contact angle of No. 3 is 150 °, the roll angle is 3 °; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

Example 4

The difference between this example and example 1 is that the hydrophobic silane of the hydrophobic coating liquid can be used in combination (various mixtures) to prepare a hydrophobic coating liquid with a solid content of 4% as shown in the following table 5:

TABLE 5

Raw materials	Solids content 4%
		Ethanol	58.92％
Silica solution	40％
		Propyl trimethoxysilane	0.5％
Polydimethylsiloxane	0.5％
		Acetic acid solution	0.08％

1. Ethanol solution (17.676 kg, 58.92% and 12kg, 40%) and silica solution were mixed and blended uniformly by a high-speed disperser for 10min;

2. adding acetic acid solution (0.024 kg, 0.08% ratio), and dispersing with high speed dispersing machine for 10min;

3. then adding propyl trimethoxy silane (0.15 kg, with a ratio of 0.5%) and polydimethylsiloxane (0.15 kg, with a ratio of 0.5%), and titrating with a peristaltic pump (parameters: 15 g/min) for 40min;

4. after the titration is finished, the mixture is dispersed for 3 hours at a high speed;

5. ultrasonic vibration for 1 hour (clear water is changed every 15min to prevent the temperature of the vibration pool from being too high);

6. 30kg of a hydrophobic coating liquid having a solids content of 4% was formed.

Wherein the mass concentration of silicon dioxide in the silicon dioxide solution is 10%.

Example 5

The difference between this example and example 1 is that the pH adjuster of the hydrophobic coating liquid can be used in combination (various mixtures) to prepare a hydrophobic coating liquid with a solid content of 4%, as shown in table 6 below:

TABLE 6

Raw materials	Solids content 4%
		Ethanol	58.92％
Silica solution	40％
		PolydimethylAzidosiloxanes	1％
Hydrochloric acid solution	0.04％
		Acetic acid solution	0.04％

1. Ethanol solution (17.676 kg, 58.92% and 12kg, 40%) and silica solution were mixed and uniformly blended for 10min by a high-speed disperser;

2. hydrochloric acid solution (0.012 kg, 0.04% by weight) and acetic acid solution (0.012 kg, 0.04% by weight) were added, and dispersed for 10 minutes using a high-speed dispersing machine; the concentration of the hydrochloric acid solution is 2wt%;

3. then adding dimethyl siloxane (0.3 kg, 1% of the ratio), titrating with peristaltic pump (parameter: 15 g/min) for 40min;

Example 6

The difference between this example and example 1 is that the alcohol substances of the hydrophobic coating liquid can be used in combination (various mixtures), for example, to prepare a hydrophobic coating liquid with a solid content of 4%, as shown in the following table 7:

TABLE 7

Raw materials	Solids content 4%
		Ethanol	35.352％
Isopropyl alcohol	23.568％
		Silica solution	40％
Polydimethylsiloxane	1％
		Acetic acid solution	0.08％

1. Ethanol solution (10.6056 kg, 35.352% by weight), isopropyl alcohol solution (7.0704 kg, 23.568% by weight) and silica solution (12 kg, 40% by weight) were mixed, and uniformly blended for 10 minutes using a high-speed disperser;

Wherein the mass concentration of silicon dioxide in the silicon dioxide solution is 10%. The solvent is anhydrous ethanol and anhydrous isopropanol with the concentration of 99.9 percent.

The coating of the coverlay was carried out using the hydrophobic coating liquid having a solid content of 4% in examples 4 to 6 described above,the specific coating process comprises the following steps: the hydrophobic coating liquid was poured into the coating tank, and the hydrophobic coating liquid was coated on the cover film roll film by running the coating roll of the wire 120 wire, coating speed: 60m/min, and finally drying in four sections of drying channels with drying parameters of 55-75-85-95 ℃ for 4 times to obtain the dry adhesive with the dry adhesive weight of 0.84g/m ² Is not stained with milk cover film.

The non-milk-sticky cover film prepared by the embodiment is applied to high-viscosity yoghourt with the viscosity in the range of 13000-18000cps, and the detection result is as follows: (1) no large area powder falling is observed by naked eyes; (2) contact angle 150 °, roll angle 3 °; (3) When the coating is left standing for 3 months, the non-stick effect is not invalid, and the phenomenon of powder falling (coating solid falling) does not occur.

Example 7

The difference from example 1 is that the solid content of the hydrophobic coating liquid in this example is different from the loading of the non-milky coating in the non-milky cover film after coating.

The solid content of the hydrophobic coating liquid is 12%, and the specific preparation process comprises the following steps:

1. ethanol solution (11.076 kg, 36.92% by weight) and silica solution (18 kg, 60% by weight) were uniformly blended for 10min with a high-speed disperser;

3. then, polydimethylsiloxane (0.9 kg, 3%) was added, titrated with peristaltic pump, titration parameters: 15g/min for 40min;

6. 30kg of a hydrophobic coating liquid having a solids content of 12% was formed.

Wherein the mass ratio of the silicon dioxide in the silicon dioxide solution is 20%.

The non-tacky film was obtained by the same coating process as in example 1, and after 1 coating, a dry gel of 0.77g/m was obtained ² Is not stained with milk cover film.

The non-milk-sticky cover film prepared by the embodiment is applied to the high-viscosity yoghourt, and the detection result is as follows: the paint has good non-stick effect, a contact angle of 150 degrees and a rolling angle of 3 degrees; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

Example 8

The solid content of the hydrophobic coating liquid is 2%, and the specific preparation process comprises the following steps:

1. ethanol solution (26.385 kg, 87.95% duty) and silica solution (3 kg, 10% duty) were mixed and uniformly blended for 10min with a high-speed disperser;

2. adding acetic acid solution (0.015 kg, 0.05% of the ratio), and dispersing with a high-speed dispersing machine for 10min;

3. then adding dimethyl siloxane (0.6 kg, 2% of the ratio), titrating with peristaltic pump (parameter: 15 g/min) for 40min;

6. 30kg of a hydrophobic coating liquid having a solids content of 2% was formed.

The non-stick cover film was obtained by the same coating process as in example 1, and after 6 times of coating, a dry gel amount of 0.65g/m was obtained ² Is not adhered to the cover film.

The non-milk-sticky cover film prepared by the embodiment is applied to the high-viscosity yoghourt, and the detection result is as follows: the paint has good non-stick effect, a contact angle of 150 degrees and a rolling angle of 5 degrees; standing for 3 months, wherein the non-stick effect is not invalid; no powder falling (coating solid falling off) occurs.

Comparative example 1

The difference between this example and example 1 is that the non-milk-sticky coating in this comparative example has different raw material compositions and proportions, and the rest is the same as example 1, and the composition of this comparative example is shown in the following table 8:

TABLE 8

Ethanol solution	67.95％
		Silica solution	30％
Isopropyl alcohol	2％
		Methyl alcohol	0.05％

The hydrophobic coating liquid with 3 percent of solid content is coated for 4 times, and the obtained dry gel amount is 0.62g/m ² The effect is as follows:

the non-stick effect is good: contact angle 150 ℃; the rolling angle is 5 ℃; standing for 3 months, wherein the non-stick effect has failure condition; no powder falling (coating solid falling off) occurs.

Comparative example 2

The anti-adhesion layer scheme disclosed in the comparative document CN105835452a specifically comprises: the anti-adhesion layer of the serial number 3 in the page table 1 of the document 13 has the best non-stick effect on the yoghurt (the best word is used in the document), but does not relate to the viscosity of the yoghurt, so the anti-adhesion layer is prepared by adopting the same raw materials and proportions, and then is applied to the high-viscosity yoghurt (the viscosity 13000-18000 cps) of the invention, the anti-adhesion layer is placed for 14 days at rest, the non-stick effect is attenuated, the non-stick effect related in the serial number 3 is placed for 3 months at rest, and the non-stick effect related in the serial number 3 has failure condition.

Comparative example 3

The difference between this example and example 1 is that the mass ratio of the solid particles to the hydrophobic silane in this comparative example is 1:1, the specific ratios are shown in Table 9 below, and the remainder are the same as in example 1.

TABLE 9

Raw materials	The solid content is 3%	Solids content 4%	The solid content is 5%
				Ethanol	66.92％	55.94％	44.95％
Silica solution	30％	40％	50％
				Polydimethylsiloxane	3％	4％	5％
Acetic acid solution	0.08％	0.06％	0.05％

After the hydrophobic coating liquid is coated, the test shows that the excessive increase of the polydimethylsiloxane can 'fill up' gaps among silicon dioxide molecules, so that the effect of the silicon dioxide salient points is invalid, and the contact angle and the rolling angle can be obviously changed. Wherein, the contact angle is only 70-90 degrees, the rolling angle is only 35-45 degrees, and the non-stick effect is not achieved.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims

1. The milk-proof cover film is characterized in that a milk-proof coating is arranged on the inner layer of the cover film; the load capacity of the non-sticky coating on the cover film is 0.62-0.84g/m ² ；

The raw materials of the non-milk-sticky coating consist of solid particles, hydrophobic silane, a pH regulator and a solvent; the mass ratio of the solid particles to the hydrophobic silane is (1.5-6): 1, a step of; the solid particles are 3-6% of the total amount of the raw materials, and the pH value of the raw materials is 6.8-7.2;

the hydrophobic silane is at least one of aminopropyl triethoxysilane, propyl trimethoxysilane or polydimethylsiloxane;

the solid particles are at least one of silicon dioxide, zinc oxide, titanium dioxide and calcium carbonate; the particle size of the solid particles is between 500nm and 2000 nm;

the pH regulator is at least one of acetic acid, hydrochloric acid, sulfuric acid or citric acid;

the solvent is an alcohol substance with the mass concentration higher than 90%.

2. The non-stick cover film of claim 1, wherein the alcohol is at least one of ethanol, isopropanol, n-butanol, or n-hexanol.

3. The method for preparing the non-milk-sticky cover film as claimed in claim 1 or 2, which is characterized by comprising the steps of coating the raw materials of the non-milk-sticky coating on the inner layer of the cover film and curing.

4. A method of manufacturing according to claim 3, wherein the cover film is a roll film, and the coating process is: pouring the raw materials of the non-milky coating into a coating groove, and coating on a coiled film by using a coating roller.

5. The preparation method according to claim 4, wherein the coating roller is an anilox roller, the mesh specification on the anilox roller is 120 lines, the coating times are 1-4 times, and the coating speed is 60m/min; the curing temperature is 50-100 ℃.

6. The method according to any one of claims 3 to 5, wherein the non-milk-sticky coating is prepared by the following steps:

and (5) oscillating for at least 30min by adopting ultrasonic waves.

7. A method according to claim 6, wherein the stirring conditions are 500-1000 r/min; the oscillation temperature is lower than 35 ℃.

8. The method of claim 6, wherein the oscillating temperature is controlled by a water bath, and the water in the water bath is replaced every 15 minutes during the oscillating process.