CN113442532B

CN113442532B - Antibacterial milky white high-temperature cooking PP sealing easy-to-open cover film and preparation method thereof

Info

Publication number: CN113442532B
Application number: CN202010219472.1A
Authority: CN
Inventors: 张瑜
Original assignee: Shantou Huicheng Packaging Material Industrial Co ltd
Current assignee: Shantou Huicheng Packaging Material Industrial Co ltd
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2023-04-28
Anticipated expiration: 2040-03-25
Also published as: CN113442532A

Abstract

A bacteriostatic milky white high-temperature cooking PP sealing easy-to-uncover film, wherein a corona layer is a blend of homopolypropylene resin and a first processing aid; the middle layer is a blend of random block copolymerized polypropylene, white master batch and first processing aid; the inner layer is a blend of (45-55): (35-40): (8-10): (1-5): 1:1:1 ratio of (45-40): (8-10): (1-5): (1:1:1) of random block copolymerized polypropylene, low-density polyethylene terephthalate, modified chitosan powder and erucamide; the corona layer, the middle layer and the inner layer form macroscopic layering from outside to inside, and a sub-microscopic composite structure is formed between the two bonding surfaces which are bonded with each other, so that the bonding force between the sub-microscopic composite structure and PP plastic is good, the airtight sealing of the content can be effectively formed, and meanwhile, the sub-microscopic composite structure has the advantages of easy uncovering, good blocking resistance and no dust drop after uncovering.

Description

Antibacterial milky white high-temperature cooking PP sealing easy-to-open cover film and preparation method thereof

Technical Field

The invention relates to the field of PP material sealing films, in particular to a bacteriostatic milky white high-temperature cooking PP sealing easy-to-uncover film and a preparation method thereof.

Background

The PP plastic is widely applied to food packaging, and in the occasion of ensuring the freshness of the content, the PP film with antibacterial property can play a role in promoting antibacterial capability, so chitosan is currently used as an antibacterial material to be added to the PP plastic so as to enhance the antibacterial capability of the PP plastic, but the stiffness and heat resistance of the PP plastic can be reduced due to the addition of the chitosan, and the bonding compactness between the PP plastic and other film layers or sealing areas is reduced, so that the good sealing effect is not beneficial to being maintained. The binding force between the chitosan PP film and the sealing area needs to be controlled, so that the chitosan PP film can cope with commercial sterilization, and is easy to uncover when in use, for example, the film is easy to crack or the sealing part is damaged due to insufficient binding force of an inner layer under the application scene of packaging and preserving fresh food.

Disclosure of Invention

The invention aims to provide an antibacterial milky white high-temperature cooking PP sealing easy-uncovering film which has good binding force with PP plastic, can effectively form airtight sealing on contents, has easy-uncovering property, has good anti-blocking property and does not fall off dust after uncovering.

In order to achieve the above purpose, the invention is implemented by adopting the following technical means:

the utility model provides a bacteriostasis milky white high temperature cooking PP seals and easily covers membrane, includes corona layer, intermediate level, inlayer from outside to inside, and corona layer, intermediate level, inlayer form macroscopic layering, form sub-microcosmic composite structure between two laminating faces of laminating mutually, wherein:

the corona layer is a blend of the homopolypropylene resin and the first processing aid;

the middle layer is a blend of random block copolymerized polypropylene, white master batch and first processing aid;

the inner layer is a blend of (45-55): (35-40): (8-10): (1-5): 1:1:1 ratio of (45-40): (8-10): (1-5): (1:1:1) of random block copolymerized polypropylene, low-density polyethylene terephthalate, modified chitosan powder and erucamide;

the opening agent is one or a combination of more of silicon dioxide, diatomite and talcum powder;

the first processing aid is a blend of fluorine-containing resin, silicone and polyacrylic acid in the ratio of (1-2) to (1-2);

the second processing aid is a blend of fluorine-containing resin, silicone and EDC and NHS in the ratio of (5-15), 1-2 and 1-2.

Further, the corona layer is a blend formed by the homopolypropylene resin and the processing aid in a ratio of 100:0.5-2;

the intermediate layer is a blend of random block copolymerized polypropylene, white master batch and processing aid in a ratio of 80-85:15-20:1, and the white master batch is rutile titanium white master batch.

Further, the modified chitosan powder is prepared by the following processing method:

(1) Soaking clean shrimp and crab shells with dilute hydrochloric acid to remove calcium carbonate, taking out insoluble matters, washing with water, drying, crushing, soaking with sodium hydroxide, taking out insoluble powder, adding into water, boiling to remove protein, and obtaining coarse chitin;

(2) Decolorizing the crude chitin by using 0.8% -1% potassium permanganate solution, washing with water, transferring decolorized crude chitin powder into oxalic acid, and reacting at 60-70deg.C for 30-45min to obtain modified chitin powder;

(3) Soaking the modified chitin powder in concentrated sodium hydroxide solution, reacting at 120 ℃ for 30-45min, adding diluted hydrochloric acid for neutralization, adding excessive acetone into the mixed solution, extracting, filtering the precipitate, washing the precipitate with water to be weak acidity, drying at 60-75 ℃, and grinding white or semitransparent chitosan crystals into powder to obtain the modified chitosan powder.

Further, in the step (3), white or semitransparent chitosan crystals are ground to 400-500 meshes of powder to obtain the modified chitosan powder.

As an effective embodiment, the thickness ratio of the corona layer, the middle layer and the inner layer is 1 (1-3): 1.

The invention also provides a manufacturing method of the easy-to-uncover cover film, which is prepared through the following steps:

(1) Preparation of corona layer: adding materials required by the corona layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form a corona layer molten material, and then feeding the corona layer molten material into a co-extrusion die head to carry out co-extrusion with middle layer molten materials and inner layer molten materials from other extruders;

(2) Preparation of an intermediate layer: adding materials required by the middle layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form a middle layer molten material, and then feeding the middle layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and inner layer molten materials from other extruders;

(3) Preparation of the inner layer: adding the materials required by the inner layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form an inner layer molten material, and then feeding the inner layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and middle layer molten materials from other extruders;

melt film coextrusion: and (3) coextruding the melts of the corona layer, the middle layer and the inner layer in a coextrusion die head at 170-185 ℃ in proportion, sequentially superposing the melts of the corona layer, the middle layer and the inner layer from outside to inside to form a melt film, then quenching the melt film after inflation, and carrying out corona treatment on the corona layer to obtain the easy-to-uncover film.

The invention has the following advantages:

1. by activating carboxyl by EDC/NHS, the carboxyl at the end of polyethylene terephthalate and the amino of weak acid chitosan generate amide reaction, so that when the inner layer and the middle layer are co-extruded and coated, the polypropylene and the low-density polyethylene are crosslinked in the submicron composite layer, and the tightness between the two sides is enhanced, so that the binding force of the inner layer and the middle layer is improved, and meanwhile, the film uncovering dust generated by film uncovering in a sealing area is reduced;

2. the melting temperatures of the corona layer, the middle layer and the inner layer are reasonably regulated, so that the two surfaces of the middle layer can be in a melting viscous flow state, and the low-density polyethylene in the melting viscous flow state can be mutually diffused, permeated and wound in a polypropylene molecular chain segment to play a role in promoting the binding force of the submicron composite layer;

3. the antibacterial force of the inner layer is pertinently improved, and the binding force of the inner layer and the PP is stronger; after the outer corona layer is subjected to corona treatment, the printing capacity can be greatly improved, and the printing material is suitable for being used as an outer package.

Detailed Description

The following examples are illustrative of various embodiments of the invention and are not intended to limit the inventive subject matter or the application and uses of the inventive subject matter.

Example 1

Preparing materials: the components are prepared according to the following material proportions:

corona layer: 100g of homopolypropylene resin, 0.5g of fluorine-containing resin, 0.5g of silicone and 1g of polyacrylic acid;

an intermediate layer: 170g of random block copolymerized polypropylene, 30g of commercial white masterbatch, 0.2g of fluorine-containing resin, 0.3g of silicone and 3g of polyacrylic acid;

an inner layer: 55g of random block copolymerized polypropylene, 35g of low-density polyethylene, 10g of polyethylene terephthalate, 3g of modified chitosan powder, 1g of erucamide, 0.5g of silicon dioxide, 0.5g of talcum powder, 0.4g of fluorine-containing resin, 0.5g of silicone, 0.04g of EDC and 0.06g of NHS;

the processing process comprises the following steps:

(1) Preparation of corona layer: adding materials required by the corona layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-175 ℃ to form a corona layer molten material, and then feeding the corona layer molten material into a co-extrusion die head to carry out co-extrusion with middle layer molten materials and inner layer molten materials from other extruders;

(2) Preparation of an intermediate layer: adding materials required by the middle layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 170-180 ℃ to form a middle layer molten material, and then feeding the middle layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and inner layer molten materials from other extruders;

(3) Preparation of the inner layer: adding the materials required by the inner layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-170 ℃ to form an inner layer molten material, and then feeding the inner layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and middle layer molten materials from other extruders;

Example 2

Corona layer: 100g of homopolypropylene resin, 0.6g of fluorine-containing resin, 0.6g of silicone and 0.6g of polyacrylic acid;

an intermediate layer: 245g of random block copolymerized polypropylene, 52.5g of commercial white masterbatch, 1g of fluorine-containing resin, 1.75g of silicone and 1.75g of polyacrylic acid;

an inner layer: 50g of random block copolymerized polypropylene, 38g of low-density polyethylene, 9g of polyethylene terephthalate, 2g of commercially available modified chitosan powder, 1g of erucamide, 0.5g of silicon dioxide, 0.5g of talcum powder, 0.4g of fluorine-containing resin, 0.5g of silicone, 0.035g of EDC and 0.065g of NHS;

the processing process comprises the following steps:

Example 3

Preparing materials:

preparation of modified chitosan:

(1) Soaking clean crab shells with dilute hydrochloric acid to remove calcium carbonate, taking out insoluble matters, washing with water, drying, crushing, soaking with sodium hydroxide, taking out insoluble powder, adding into water, boiling to remove protein, and obtaining coarse chitin;

(2) Decolorizing the crude chitin by using 0.8% -1% potassium permanganate solution, washing with water, transferring decolorized crude chitin powder into oxalic acid, and reacting at 65-70deg.C for 45min to obtain modified chitin powder;

(3) Soaking the modified chitin powder in concentrated sodium hydroxide solution, reacting at 120 ℃ for 30min, adding diluted hydrochloric acid for neutralization, adding excessive acetone into the mixed solution, extracting, filtering the precipitate, washing the precipitate with water until the pH value is equal to 6, drying at 60-75 ℃, and grinding the white or semitransparent chitosan crystal to 400-500 meshes to obtain modified chitosan for later use.

The modified chitosan prepared in this example was used as example 3 in place of the commercially available chitosan used in example 2, in combination with the rest of the materials and the manufacturing method of example 2, to prepare a corresponding easy-to-open film.

Characterization of

The easy-to-uncover films prepared in examples 1-3 were subjected to performance measurement and used as heat-seal films of PP boxes to establish test groups; meanwhile, a comparison group is established for the common PP heat-sealing film sold in the market;

and establishing a test group and an empty packet group from the groups, wherein:

the test group is to put bean curd in the PP box body and PET box body, seal the film (inner layer is sealed inwards), sterilize by steam heat at 120 ℃ for 30min, cool in refrigerator at 5 ℃ for 10 days, observe the state;

the empty package group was heat sealed by using the heat-sealing film prepared in examples 1 to 3, and was directly placed in a refrigerator for cold storage at 5℃for 10 days.

The blank of the test group was tested at a tensile speed of 300mm/min using a peel strength tester to compare the difference in heat seal strength and blocking resistance, and the results are shown in Table 1; and is opposite to

TABLE 1 Performance measurement data for the inventive easy-to-open films

Table 2 sensory comparison of the inventive loaded tofu on day 10

From the data in tables 1-2, it can be seen that the peeling strength of examples 1-3 was reduced after heating and boiling, but cracking did not occur, and that the heat seal strength was in the range of 12-16N/15mm under the conditions of a tensile speed of 300mm/min, and that example 3 was considered to be more friendly in terms of easy peeling, although exceeding, with less deviation; and a shear peel force of less than 18N/12cm ² In the case of (2), it is considered that the anti-blocking effect is superior.

From the indexes, the heat sealing strength of the easy-to-open film in the embodiment 1 is reduced after heat treatment, and the heat sealing strength is still in a reasonable range, so that the easy-to-open film is more suitable for sealing packaging after heat sealing packaging for short time heat treatment; example 3 is more stable after heat treatment than examples 1, 2, and it is inferred that the effect of heat treatment on the film is smaller and the heat sealing effect is more stable from the sensory evaluation result on the preservation of tofu.

It will be apparent to those skilled in the art that the present invention has been described in detail by way of illustration only, and it is not intended to be limited by the above-described embodiments, as long as various insubstantial modifications of the method concepts and aspects of the invention are employed or the inventive concepts and aspects of the invention are directly applied to other applications without modification, all within the scope of the invention.

Claims

1. The utility model provides a bacteriostasis milky white high temperature cooking PP seals and easily covers membrane, from outside to inside includes corona layer, intermediate level, inlayer, and corona layer, intermediate level, inlayer form macroscopic layering, form sub-microcosmic composite construction between two laminating faces of laminating mutually, its characterized in that:

the corona layer is a blend of homopolypropylene resin and a first processing aid;

the inner layer is a blend of (45-55): (35-40): (8-10): (1-5): 1:1:1 ratio of (45-55): (35-10): (1-5): (1:1:1) of random block copolymerized polypropylene, polyethylene terephthalate, modified chitosan powder and erucamide; the modified chitosan powder is slightly acidic;

the second processing aid is a blend formed by a ratio of (5-15): (5-15): (1-2): (1-2) of fluorine-containing resin, silicone and EDC and NHS; and during the processing, EDC/NHS makes the carboxyl end of polyethylene terephthalate and amino of weak acid chitosan undergo the amide reaction.

2. The bacteriostatic milky white high-temperature cooking PP sealing easy-uncovering film according to claim 1, wherein the corona layer is a blend formed by homopolypropylene resin and processing aid in a ratio of 100:0.5-2;

3. The bacteriostatic milky white high-temperature steamed PP sealing easy-uncovering film according to claim 1, wherein the modified chitosan powder is prepared by the following processing method:

soaking clean shrimp and crab shells with dilute hydrochloric acid to remove calcium carbonate, taking out insoluble matters, washing with water, drying, crushing, soaking with sodium hydroxide, taking out insoluble powder, adding into water, boiling to remove protein, and obtaining coarse chitin;

decolorizing the crude chitin by using 0.8% -1% potassium permanganate solution, washing with water, transferring decolorized crude chitin powder into oxalic acid, and reacting at 60-70deg.C for 30-45min to obtain modified chitin powder;

soaking the modified chitin powder in concentrated sodium hydroxide solution, reacting at 120 ℃ for 30-45min, adding diluted hydrochloric acid for neutralization, adding excessive acetone into the mixed solution, extracting, filtering the precipitate, washing the precipitate with water to be weak acidity, drying at 60-75 ℃, and grinding white or semitransparent chitosan crystals into powder to obtain the modified chitosan powder.

4. The bacteriostatic milky white high-temperature steamed PP sealing easy-uncovering film according to claim 3, wherein the white or semitransparent chitosan crystal is ground into powder with 400-500 meshes, and the modified chitosan powder is obtained.

5. The bacteriostatic milky high-temperature steamed PP sealing easy-open film according to any one of claims 1-4, wherein the thickness ratio of the corona layer, the middle layer and the inner layer is 1 (1-3): 1.

6. A method for preparing the bacteriostatic milky white high-temperature cooking PP sealing easy-to-open film according to any one of claims 1-5, which is characterized by the following steps:

preparation of corona layer: adding materials required by the corona layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form a corona layer molten material, and then feeding the corona layer molten material into a co-extrusion die head to carry out co-extrusion with middle layer molten materials and inner layer molten materials from other extruders;

preparation of an intermediate layer: adding materials required by the middle layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form a middle layer molten material, and then feeding the middle layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and inner layer molten materials from other extruders;

preparation of the inner layer: adding the materials required by the inner layer into a stirrer according to a proportion, stirring uniformly, and carrying out blending extrusion at a melting temperature of 165-180 ℃ to form an inner layer molten material, and then feeding the inner layer molten material into a co-extrusion die head to carry out co-extrusion together with corona layer molten materials and middle layer molten materials from other extruders;