阅读说明：本技术 阻光收缩膜及其制备方法 (Light-blocking shrink film and preparation method thereof ) 是由 冯益强 刘希军 李光耀 尹长奇 王凯 于 2020-06-09 设计创作，主要内容包括：本发明涉及一种阻光收缩膜及其制备方法,属于热收缩聚酯薄膜技术领域。本发明所述的阻光收缩膜,至少包括A层和B层,其中：B层为黑色阻光层,包括以下质量百分含量的原料：0.1-30％的黑色遮蔽剂,70-99.9％的改性聚对苯二甲酸乙二醇酯；A层为B层黑色阻光层的白色遮蔽层,包括以下质量百分含量的原料：5-60％的白色遮蔽剂,40-95％的改性聚对苯二甲酸乙二醇酯。本发明所述的阻光收缩膜,不仅具有优异的阻光效果,还具有优异的印刷效果和外表美观度,成本低；同时本发明提供了一种简单易行的制备方法。(The invention relates to a light-blocking shrink film and a preparation method thereof, belonging to the technical field of heat-shrinkable polyester films. The light-blocking shrink film at least comprises an A layer and a B layer, wherein: the layer B is a black light-blocking layer and comprises the following raw materials in percentage by mass: 0.1-30% of black masking agent, 70-99.9% of modified polyethylene terephthalate; the layer A is a white shielding layer of a layer B black light-blocking layer and comprises the following raw materials in percentage by mass: 5-60% of white masking agent and 40-95% of modified polyethylene terephthalate. The light-blocking shrink film disclosed by the invention has excellent light-blocking effect, excellent printing effect and attractive appearance, and is low in cost; meanwhile, the invention provides a simple and feasible preparation method.)

1. A light-blocking shrink film characterized by: at least comprising an A layer and a B layer, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 70-99.9% of modified polyethylene terephthalate;

the layer B is a white shielding layer of the layer A, and comprises the following raw materials in percentage by mass:

5-60% of white masking agent and 40-95% of modified polyethylene terephthalate.

2. The light-blocking shrink film of claim 1, wherein: is an AB two-layer or BAB, ABC, CAB three-layer structure, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 70-99.9% of modified polyethylene terephthalate;

the layer B is a white shielding layer of the layer A, and comprises the following raw materials in percentage by mass:

5-60% of white masking agent, 40-95% of modified polyethylene terephthalate;

the layer C comprises the following raw materials in percentage by mass:

0-60% of white masking agent, 40-99% of modified polyethylene terephthalate and 0-5% of opening slip agent.

3. The light-blocking shrink film of claim 1, wherein: is an AB two-layer or BAB, ABC, CAB three-layer structure, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 0-99.9% of modified polyethylene glycol terephthalate and 0-99.9% of light-blocking shrink film reclaimed material;

the layer B and the layer C are white shielding layers of the layer A black light-blocking layer and comprise the following raw materials in percentage by mass:

5-60% of white masking agent and 40-95% of modified polyethylene terephthalate.

4. The light-blocking shrink film of claim 1, wherein: is an ABC three-layer structure, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 0-99.9% of modified polyethylene glycol terephthalate and 0-99.9% of light-blocking shrink film reclaimed material;

the layer B is a white shielding layer of the layer A, and comprises the following raw materials in percentage by mass:

5-60% of white masking agent, 40-95% of modified polyethylene terephthalate;

the layer C is a printing layer and comprises the following raw materials in percentage by mass:

0-60% of white masking agent, 40-100% of modified polyethylene terephthalate and 0-5% of opening slip agent.

5. The light-blocking shrink film of claim 1, wherein: modified polyethylene terephthalate, which is copolymerized with terephthalic acid and ethylene glycol by taking one or more of diol or diacid components with the molar mass content of 7-50% as a third monomer, and taking the total mass of all monomers as a reference.

6. The light-blocking shrink film of claim 1, wherein: the black masking agent is inorganic dye, organic black pigment or organic black dye.

7. The light-blocking shrink film of claim 1, wherein: the white masking agent is an inorganic colorant or incompatible organic microparticles.

8. The light-blocking shrink film of claim 7, wherein: the inorganic colorant is one or more of titanium dioxide, calcium carbonate, barium sulfate, silicon dioxide, alumina or kaolin.

9. A method for preparing a light-blocking shrink film according to any one of claims 1 to 8, characterized in that: respectively mixing the raw materials at least comprising the layer A and the layer B, then carrying out melt extrusion, carrying out ultra-cold sheet casting, and then sequentially carrying out longitudinal stretching, transverse stretching, corona treatment and traction rolling to obtain the light-blocking shrink film.

10. The method for producing a light-blocking shrink film according to claim 9, characterized in that: the melt extrusion temperature is 200-300 ℃; stretching the longitudinal direction by 1.0-1.5 times and stretching the transverse direction by 3-6 times; after stretching, heat treatment is carried out at 60-110 ℃.

Technical Field

The invention relates to a light-blocking shrink film and a preparation method thereof, belonging to the technical field of heat-shrinkable polyester films.

Background

Polyester heat shrinkable film (PET heat shrinkable film for short) is a novel heat shrinkable packaging material, and the market demand is rapidly increased in recent years. Because the PET heat shrinkable film has the characteristics of high shrinkage, good transparency, no toxicity, no odor, good mechanical property, excellent printing performance, lower self shrinkage, relative storage resistance, environmental protection conformity and the like, the PET heat shrinkable film successfully replaces a polyvinyl chloride (PVC) heat shrinkable film in developed countries and becomes an ideal shrink packaging material.

In the use process of a common polyester shrink film, the common polyester shrink film is made of transparent materials, has small light barrier property and cannot protect a bottle body and substances sensitive to light in the bottle, and the bottle body is designed into a light-blocking material in the market at present, so that the bottle body is difficult to recycle due to the addition of a large amount of light-blocking agents.

The white shrink film and the ultraviolet-blocking shrink film products sold in the market at present still have insufficient light-blocking performance for long wavelengths such as visible light, but the damage of the light to products needing protection is still large, and the requirement of the products on quality guarantee period cannot be met. Thus, there is a need for more effective black light blockers.

After adding more effective black light-blocking agent, the surface layer needs to be covered with black due to the requirements of printing and surface beauty so as to present better advertising effect. And the recycling of the scrap becomes a problem due to the addition of the black light-blocking agent, which also increases the cost of the product.

Disclosure of Invention

The invention aims to provide a light-blocking shrink film which not only has excellent light-blocking effect, but also has excellent printing effect and beautiful appearance and low cost; meanwhile, the invention provides a simple and feasible preparation method.

The light-blocking shrink film at least comprises an A layer and a B layer, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 70-99.9% of modified polyethylene terephthalate;

the layer B is a white shielding layer of the layer A, and comprises the following raw materials in percentage by mass:

5-60% of white masking agent and 40-95% of modified polyethylene terephthalate.

The light-blocking shrink film prepared by adopting the formula meets the following conditions:

a, light transmittance is less than 1%.

And b, the shrinkage rate in the main shrinkage direction of the water bath at 100 ℃ for 10 seconds is more than 40%.

And c, the shrinkage rate in the direction perpendicular to the main shrinkage direction in a water bath for 10 seconds at 100 ℃ is less than 10%.

d, the thickness of the B layer is more than 10 microns, and the B layer is used as a white shielding layer of the printing layer to the black layer.

As a preferred scheme, the light-blocking shrink film is a three-layer structure of BAB, ABC and CAB:

wherein, the layer A and the layer B are prepared as above, and the layer C comprises the following raw materials in percentage by mass:

0-60% of white masking agent, 40-99% of modified polyethylene terephthalate and 0-5% of opening slip agent.

The light-blocking shrink film prepared by adopting the formula meets the same conditions as the above conditions, and has the following difference:

at least one layer of the B layer and the C layer has a thickness of more than 10 microns and is used as a white shielding layer facing the black layer.

As a preferable scheme, the light blocking shrink film is a BAC or BAB three-layer structure, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 0-99.9% of modified polyethylene glycol terephthalate and 0-99.9% of light-blocking shrink film reclaimed material;

the layer B and the layer C are white shielding layers of the black light-blocking layer of the layer A, wherein the layer B comprises the following raw materials in percentage by mass:

5-60% of white masking agent and 40-95% of modified polyethylene terephthalate. Wherein the layer C comprises the following raw materials in percentage by mass: 0-60% of white masking agent, 40-99% of modified polyethylene terephthalate and 0-5% of opening slip agent.

The light-blocking shrink film prepared by adopting the formula meets the following conditions:

a, light transmittance is less than 1%.

And b, the shrinkage rate in the main shrinkage direction of the water bath at 100 ℃ for 10 seconds is more than 40%.

And c, the shrinkage rate in the direction perpendicular to the main shrinkage direction in a water bath for 10 seconds at 100 ℃ is less than 10%.

d, the thickness of the B layer is more than 10 microns, the B layer is used as a white shielding layer of the printing layer to the black layer, and the thickness of the C layer is at least 2 microns, so that the effect of shielding and beautifying the black shielding layer is achieved.

As a preferable scheme, the light-blocking shrink film is an ABC, BAB three-layer structure, wherein:

the layer A is a black light-blocking layer and comprises the following raw materials in percentage by mass:

0.1-30% of black masking agent, 0-99.9% of modified polyethylene glycol terephthalate and 0-99.9% of light-blocking shrink film reclaimed material;

the layer B is a white shielding layer of the layer A, and comprises the following raw materials in percentage by mass:

5-60% of white masking agent, 40-95% of modified polyethylene terephthalate;

the layer C is a printing layer and comprises the following raw materials in percentage by mass:

0-60% of white masking agent, 40-100% of modified polyethylene terephthalate and 0-5% of opening slip agent.

The light-blocking shrink film prepared by adopting the formula meets the following conditions:

a, light transmittance is less than 1%.

And b, the shrinkage rate in the main shrinkage direction of the water bath at 100 ℃ for 10 seconds is more than 40%.

And c, the shrinkage rate in the direction perpendicular to the main shrinkage direction in a water bath for 10 seconds at 100 ℃ is less than 10%.

d, the thickness of the B layer is more than 10 microns, and the B layer is used as a white shielding layer of the printing layer to the black layer.

The modified polyethylene terephthalate is prepared by copolymerizing one or more of common diol or diacid components with the molar mass content of 7-40 percent (based on the total mass of all monomers) as a third monomer with terephthalic acid and ethylene glycol.

The third monomer diacid for modifying the polyethylene terephthalate can be phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, adipic acid, azelaic acid, decanedicarboxylic acid sebacate, 1, 4-cyclohexanedicarboxylic acid and the like.

The third monomer glycol for modifying the polyethylene terephthalate can be 2, 2-dimethyl-1, 3-propanediol, 2-n-butanol-2-ethyl-1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, hexanediol, 1, 4-cyclohexanedimethanol, ethylene glycol monobutyl ether and the like.

The third monomer diol or diacid may be a copolymer of one, two or more diols or diacids, or a copolymerized blend.

The third monomer diol or diacid of the modified polyethylene terephthalate accounts for more than 7 percent and less than 40 percent of the total mole content of the diol or diacid, the shrinkage rate of the third monomer diol or diacid is not enough to obtain more than 40 percent of the shrinkage rate in 100 ℃ water bath for 10 seconds, and the use effect is influenced because the strength of the film is reduced by more than 40 percent. More preferably, it is 15% or more and 30% or less.

The black masking agent is inorganic dye such as carbon black and graphite, and can also be organic black pigment and organic black dye. Mixtures of the above materials are possible.

The black masking agent accounts for the total weight of the film, and the content of the black masking agent is less than 0.1 percent, so that the masking effect is poor; the shielding layer is required to be thick to achieve a good shielding effect, and the content of the shielding layer is more than 30%, the dispersion is difficult and the strength performance of the film is influenced, and more preferably more than 1% and less than 20%.

The white shielding agent is one or more inorganic coloring agents selected from titanium dioxide, calcium carbonate, barium sulfate, silicon dioxide, aluminum oxide, kaolin and the like, and also comprises incompatible organic microparticles, such as acrylic resin particles, melamine resin particles, silicone resin particles, crosslinked polystyrene particles, polypropylene, PMP, COC and other cyclic olefin resin particles, triacetate fiber resin particles and the like. Two or more of the above materials may be used in combination.

When the content of the white shielding agent is less than 5%, the thickness of the white shielding layer for shielding the black shielding layer needs to be very thick, and exceeds the range of practical application, and when the content is more than 60%, the dispersion of the shielding agent is difficult, and the product strength performance of the film is also influenced. More preferably 10% to 50%.

The thickness of the white shielding layer is more than 10 microns, and if the thickness of the white shielding layer is less than 10 microns, enough white shielding particles are difficult to disperse in the white shielding layer so as to shield the color of the black harmonic shielding layer, and the beautiful effect cannot be achieved.

The opening slip agent is silicon dioxide, mica powder, alumina, kaolin, paraffin and the like.

To the raw material for forming the light-blocking shrink film of the present invention, various additives such as waxes, antioxidants, antistatic agents, nucleating agents, viscosity reducers, tackifiers, chain extenders, heat stabilizers, coloring pigments, anti-coloring agents, anti-uv absorbers, and the like may be added as necessary.

The light transmittance of the light-blocking shrink film is less than 1%, and if the light transmittance is more than 1%, the shelf life of the product is influenced. More preferably, it is less than 0.5%, and still more preferably less than 0.1%.

The layers a, B and C described in the present invention are merely referred to for distinguishing the number of layers, and are not limited to a specific layer.

The preparation method of the light-blocking shrink film comprises the following steps:

(1) mixing the corresponding raw materials at least comprising the layer A, the layer B, the layer C and the like, drying the mixture for 4 hours at 65 ℃ in dry air, extruding the mixture by using respective extruders, and if a vacuumizing double-screw extruder is used, the drying can be avoided. The extrusion temperature is 200-300 ℃;

(2) the melt extruded by each extruder enters a multilayer adapter through a respective filter metering pump and the like to form a mixture of a multilayer structure, and then flows out through a T-shaped die head to form the required sheet-shaped molten resin with the multilayer structure. Or preferably, a multilayer die head is used for converging and mixing at the position close to the outlet of the die head to form a multilayer co-extruded sheet-shaped outflow layer, so that the thickness uniformity of each layer can be maintained easily by the outflow layer, and the stability of the product quality is maintained;

(3) cooling the sheet-like outflow melt layer on a sheet casting roller at about 30 ℃ to form an unstretched sheet;

(4) performing single or bidirectional stretching at 10-50 deg.C higher than softening point, optionally longitudinal or transverse unidirectional stretching, optionally simultaneously longitudinal and transverse stretching, with no limitation on the sequence of transverse and longitudinal directions, or synchronous bidirectional stretching;

in this case, it is preferable to perform stretching in the longitudinal direction by 1.0 to 1.5 times and stretching in the transverse direction by 3 to 6 times, in order to achieve relatively high productivity in the transverse direction, and to suitably improve the longitudinal tensile strength in the longitudinal direction, which is advantageous for the stability of the subsequent processing and use processes. After stretching, heat treatment can be carried out at 60-110 ℃;

(5) after longitudinal stretching, one or two surfaces of the film can be subjected to coating treatment, and the coating can be a smooth coating, an antistatic coating, an antibacterial coating and the like and is used for improving the adhesive force;

(6) coiling the film into a large roll after trimming, or carrying out corona treatment before coiling;

(7) and cutting into the specifications required by the customers and packaging.

The light-blocking shrink film prepared by the invention is treated in water bath at 100 ℃ for 10 seconds, and has the shrinkage rate of more than 40% in the main shrinkage direction and the shrinkage rate of less than 10% in the direction perpendicular to the main shrinkage direction; the light transmittance is less than 1%.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the black masking agent is added in a certain proportion, so that the product has excellent light resistance;

(2) in order to realize that the printing effect is not influenced by the black color, the shielding agent with a certain proportion is added, so that the black color layer is shielded, and meanwhile, the printing effect and the attractiveness are good;

(3) according to the invention, a certain proportion of the recycled material of the complete light-blocking shrink film or the white shielding agent is added into the black shielding layer, so that the recycled material is fully utilized to reduce the cost; the white shielding agent can neutralize the black color, so that the black color is more easily shielded, and the aesthetic degree is improved; the white shielding agents are used on the two sides of the black shielding agent, so that the influence of black pigment on the use process is avoided, and a better attractive effect is achieved;

(4) the preparation method of the light-blocking shrink film is simple and feasible and is beneficial to industrial production.

Detailed Description

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to these examples.