A pearl label film and a method for manufacturing the same

Abstract

The application discloses a pearl label film and a preparation method thereof, and relates to the technical field of film materials.The pearl label film is a BOPP film with a five-layer structure, and sequentially comprises an upper surface layer, a secondary upper surface layer, a core layer, a secondary lower surface layer and a lower surface layer.The raw material of the upper surface layer comprises a matt agent, the raw material of the secondary upper surface layer comprises polypropylene and a whitening master batch, the raw material of the core layer comprises polypropylene, a pearl master batch and an antistatic agent, the raw material of the secondary lower surface layer comprises polypropylene, and the raw material of the lower surface layer comprises polypropylene and an anti-blocking master batch.The pearl label film has excellent mechanical properties and appearance effects, is not prone to wrinkling, and has good processing performance and use performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film materials, in particular to a pearl label film and a preparation method thereof. BACKGROUND

[0002] The BOPP pearl label film is a surface printable film product with soft pearl luster, high hiding power and good flatness, which is widely used in the packaging field of cosmetics, food and beverages. In order to achieve the soft pearl appearance effect, not only the BOPP pearl label film needs to be compounded with multiple functional layers, but also the pearl agent, whitening agent and other additives need to be added in each functional layer according to the actual needs. The use of these additives affects the uniformity of the components of each functional layer, making the material of the film uneven. This not only affects the appearance effect such as haze and gloss of the film, but also causes the BOPP pearl label film to wrinkle easily during the actual processing and use, thereby affecting the yield and product quality of the product. SUMMARY

[0003] Based on the technical problems existing in the background art, the present application provides a pearl label film with excellent mechanical properties and appearance effect, and not easy to wrinkle, and a preparation method thereof.

[0004] The present application provides a pearl label film, which is a BOPP film with a five-layer structure, including an upper surface layer, a secondary upper surface layer, a core layer, a secondary lower surface layer and a lower surface layer in sequence.

[0005] The raw material of the upper surface layer includes a matting agent;

[0006] The raw material of the secondary upper surface layer includes 80-90 parts of polypropylene and 10-20 parts of whitening masterbatch by mass fraction; the raw material of the whitening masterbatch includes 60-80 parts of polypropylene, 20-40 parts of octadecylamine modified titanium dioxide, 1-2 parts of dispersant and 0.5-1 part of antioxidant by mass fraction;

[0007] The raw material of the core layer includes 70-85 parts of polypropylene, 15-30 parts of pearl masterbatch and 0.5-2 parts of anti-static agent by mass fraction; the raw material of the pearl masterbatch includes 60-80 parts of polypropylene, 20-40 parts of modified calcium carbonate, 1-2 parts of dispersant and 0.5-1 part of antioxidant by mass fraction;

[0008] The raw material of the secondary lower surface layer includes polypropylene;

[0009] The raw material of the lower surface layer includes 80-90 parts of polypropylene and 10-20 parts of anti-blocking masterbatch by mass fraction.

[0010] Preferably, the preparation method of the octadecylamine modified titanium white powder comprises: adding titanium white powder into a silane coupling agent KH-560 solution to uniformly disperse, stirring and reacting at 40-80℃ for 2-6h, then centrifuging, washing, and drying to obtain powder A; adding the powder A into an octadecylamine ethanol solution to uniformly disperse, stirring and reacting at 40-60℃ for 5-12h, then centrifuging, washing, and drying to obtain the octadecylamine modified titanium white powder.

[0011] Preferably, the mass ratio of the titanium white powder to the silane coupling agent KH-560 is 1:1-3.

[0012] Preferably, the mass ratio of the powder A to the octadecylamine is 1:1-10.

[0013] Preferably, the preparation method of the octadecylamine modified calcium carbonate comprises: adding calcium carbonate into a silane coupling agent KH-560 solution to uniformly disperse, stirring and reacting at 40-80℃ for 2-6h, then centrifuging, washing, and drying to obtain powder B; adding the powder B into an octadecylamine ethanol solution to uniformly disperse, stirring and reacting at 40-60℃ for 5-12h, then centrifuging, washing, and drying to obtain the octadecylamine modified calcium carbonate.

[0014] Preferably, the mass ratio of the calcium carbonate to the silane coupling agent KH-560 is 1:1-3.

[0015] Preferably, the mass ratio of the powder B to the octadecylamine is 1:1-10.

[0016] Preferably, the octadecylamine ethanol solution is obtained by dissolving octadecylamine in anhydrous ethanol.

[0017] Preferably, the concentration of the octadecylamine ethanol solution is 5-20g / L.

[0018] Preferably, the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol, and water at a mass ratio of 1:5-10:3-5.

[0019] Preferably, the raw materials of the anti-adhesion masterbatch include polypropylene 90-95 parts, glass microbeads 5-10 parts, dispersant 0.5-1 part, and antioxidant 0.2-1 part in terms of mass parts; the particle size of the glass microbeads is 3-5μm.

[0020] Preferably, the dispersant is at least one of stearic acid, sodium stearate, calcium stearate, and erucylamide; the antioxidant is antioxidant 1010, antioxidant 168, or a combination thereof.

[0021] Preferably, the total thickness of the pearl label film is 35-55 μm, the thickness of the upper surface layer is 2-3 μm, the thickness of the sub-upper surface layer is 5-8 μm, the thickness of the core layer is 15-35 μm, the thickness of the sub-lower surface layer is 5-7 μm, and the thickness of the lower surface layer is 1-2 μm.

[0022] The application further discloses a preparation method of the pearl label film.

[0023] S1, melt-extruding raw materials of the upper surface layer, the sub-upper surface layer, the core layer, the sub-lower surface layer and the lower surface layer respectively to obtain upper surface layer melt, sub-upper surface layer melt, core layer melt, sub-lower surface layer melt and lower surface layer melt, and co-extruding the five layers through a five-layer structure die and cooling by a chilling roller to obtain a thick sheet;

[0024] S2, sequentially stretching the thick sheet in the longitudinal direction and the transverse direction, and then cooling and winding to obtain the pearl label film.

[0025] Preferably, in S1, the temperature for melt-extruding is 220-230 ℃.

[0026] Preferably, in S1, the cooling temperature is 30-35 ℃.

[0027] Preferably, in S2, the stretching temperature for the longitudinal stretching is 110-130 ℃, and the stretching ratio is 5-6; the stretching temperature for the transverse stretching is 160-180 ℃, and the stretching ratio is 8-9.

[0028] The application has the following beneficial effects:

[0029] The pearl label film prepared by the application has the following advantages: the whitening agent and the pearl powder are added to the sub-upper surface layer and the core layer respectively, and the titanium dioxide as the whitening agent and the calcium carbonate as the pearl powder are modified, the epoxy silane coupling agent KH-560 is grafted on the surface first, and then the octadecylamine is grafted on the surface of the powder through the action between the amine group and the epoxy group, so that the aliphatic long chain with good flexibility is grafted on the surface of the powder, which can improve the dispersibility of the titanium dioxide and the calcium carbonate in the functional layer, improve the uniformity of the functional layer of the film, improve the flexibility of the film, and effectively improve the wrinkling phenomenon of the film in the process of processing and use. DETAILED DESCRIPTION

[0030] The technical scheme of the application will be described in detail below through specific embodiments.

[0031] In the following examples and comparative examples: polypropylene is Sinopec F280; matting agent is Degao D6612 matting masterbatch; antistatic agent is Clariant FA68; dispersing agent is stearic acid; antioxidant is antioxidant 1010.

[0032] Example 1

[0033] A pearl label film is a BOPP film of five-layer structure, comprising an upper surface layer, a lower surface layer, a core layer, a lower surface layer, and a lower surface layer in turn;

[0034] The raw material of the upper surface layer is a matting agent;

[0035] The raw material of the lower surface layer is composed of 85 parts of polypropylene and 15 parts of whitening masterbatch by mass; the raw material of the whitening masterbatch is composed of 70 parts of polypropylene, 30 parts of octadecylamine modified titanium dioxide, 1.5 parts of dispersing agent, and 0.5 parts of antioxidant by mass;

[0036] The preparation method of the octadecylamine modified titanium dioxide is: the titanium dioxide is added into the silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 50℃ for 3h, then centrifuged, washed and dried to obtain powder A; the powder A is added into the ethanol solution of octadecylamine with a concentration of 10g / L and uniformly dispersed, stirred and reacted at 50℃ for 10h, then centrifuged, washed and dried, wherein the mass ratio of titanium dioxide to silane coupling agent KH-560 is 1:2, the mass ratio of powder A to octadecylamine is 1:3, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water in a mass ratio of 1:6:4;

[0037] The raw material of the core layer is composed of 80 parts of polypropylene, 20 parts of pearl masterbatch and 1 part of antistatic agent by mass; the raw material of the pearl masterbatch is composed of 70 parts of polypropylene, 30 parts of octadecylamine modified calcium carbonate, 1.5 parts of dispersing agent, and 0.5 parts of antioxidant by mass;

[0038] The preparation method of the octadecylamine modified calcium carbonate is: the calcium carbonate is added into the silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 50℃ for 3h, then centrifuged, washed and dried to obtain powder B; the powder B is added into the ethanol solution of octadecylamine with a concentration of 10g / L and uniformly dispersed, stirred and reacted at 50℃ for 10h, then centrifuged, washed and dried, wherein the mass ratio of calcium carbonate to silane coupling agent KH-560 is 1:2, the mass ratio of powder B to octadecylamine is 1:3, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water in a mass ratio of 1:6:4;

[0039] The raw material of the lower surface layer is polypropylene;

[0040] The raw material of the lower surface layer consists of 85 parts of polypropylene and 15 parts of anti-blocking masterbatch by mass fraction; the raw material of the anti-blocking masterbatch consists of 92 parts of polypropylene, 8 parts of glass beads, 0.5 parts of dispersing agent and 0.5 parts of antioxidant by mass fraction.

[0041] The total thickness of the above-mentioned pearl label film is 46 μm, the thickness of the upper surface layer is 2.5 μm, the thickness of the sub-upper surface layer is 6 μm, the thickness of the core layer is 30 μm, the thickness of the sub-lower surface layer is 6 μm, and the thickness of the lower surface layer is 1.5 μm.

[0042] The preparation method of the above-mentioned pearl label film comprises the following steps:

[0043] S1, melt-extruding the raw materials of the upper surface layer, the sub-upper surface layer, the core layer, the sub-lower surface layer and the lower surface layer at 220-230 ℃ respectively to obtain the upper surface layer melt, the sub-upper surface layer melt, the core layer melt, the sub-lower surface layer melt and the lower surface layer melt, co-extruding through a five-layer structure die, and cooling at 30-35 ℃ by means of a chilling roller to obtain a thick sheet;

[0044] S2, sequentially subjecting the thick sheet to longitudinal stretching, transverse stretching, then cooling and winding up to obtain the pearl label film; the stretching temperature for longitudinal stretching is 110-130 ℃, and the stretching ratio is 6; the stretching temperature for transverse stretching is 160-180 ℃, and the stretching ratio is 9.

[0045] Example 2

[0046] A pearl label film is a BOPP film with a five-layer structure, which comprises an upper surface layer, a sub-upper surface layer, a core layer, a sub-lower surface layer and a lower surface layer in sequence;

[0047] The raw material of the upper surface layer is a matt material;

[0048] The raw material of the sub-upper surface layer consists of 80 parts of polypropylene and 20 parts of whitening masterbatch by mass fraction; the raw material of the whitening masterbatch consists of 60 parts of polypropylene, 40 parts of titanium dioxide modified by octadecylamine, 1 part of dispersing agent and 0.5 parts of antioxidant by mass fraction;

[0049] The preparation method of the titanium dioxide modified by octadecylamine is as follows: uniformly dispersing titanium dioxide in a silane coupling agent KH-560 solution, stirring and reacting at 40 ℃ for 2 h, then centrifuging, washing and drying to obtain powder A; uniformly dispersing powder A in an ethanol solution of octadecylamine with a concentration of 5 g / L, stirring and reacting at 40 ℃ for 5 h, then centrifuging, washing and drying, wherein the mass ratio of titanium dioxide to silane coupling agent KH-560 is 1:1, the mass ratio of powder A to octadecylamine is 1:1, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:5:3;

[0050] The raw material of the core layer consists of 70 parts of polypropylene, 30 parts of pearl masterbatch and 0.5 parts of antistatic agent by mass fraction; the raw material of the pearl masterbatch consists of 60 parts of polypropylene, 40 parts of octadecylamine modified calcium carbonate, 1 part of dispersing agent and 0.5 parts of antioxidant by mass fraction;

[0051] The preparation method of the octadecylamine modified calcium carbonate is as follows: calcium carbonate is added into a silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 40℃ for 2h, then centrifuged, washed and dried to obtain powder B; powder B is added into an ethanol solution of octadecylamine with a concentration of 5g / L and uniformly dispersed, stirred and reacted at 40℃ for 5h, then centrifuged, washed and dried, wherein the mass ratio of calcium carbonate to silane coupling agent KH-560 is 1:1, the mass ratio of powder B to octadecylamine is 1:1, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:5:3;

[0052] The raw material of the sub-underlayer is polypropylene;

[0053] The raw material of the lower layer consists of 80 parts of polypropylene and 20 parts of anti-blocking masterbatch by mass fraction; the raw material of the anti-blocking masterbatch consists of 90 parts of polypropylene, 10 parts of glass microbeads, 0.5 parts of dispersing agent and 0.2 parts of antioxidant by mass fraction, wherein the particle size of the glass microbeads is 3-5μm.

[0054] The total thickness of the above-mentioned pearl label film is 46μm, the thickness of the upper layer is 2.5μm, the thickness of the sub-upper layer is 6μm, the thickness of the core layer is 30μm, the thickness of the sub-underlayer is 6μm, and the thickness of the lower layer is 1.5μm.

[0055] The preparation method of the above-mentioned pearl label film is the same as that of Example 1.

[0056] Example 3

[0057] A pearl label film is a BOPP film with a five-layer structure, which comprises an upper layer, a sub-upper layer, a core layer, a sub-underlayer and a lower layer in sequence;

[0058] The raw material of the upper layer is a matting agent;

[0059] The raw material of the sub-upper layer consists of 90 parts of polypropylene and 10 parts of whitening masterbatch by mass fraction; the raw material of the whitening masterbatch consists of 80 parts of polypropylene, 20 parts of octadecylamine modified titanium dioxide, 2 parts of dispersing agent and 1 part of antioxidant by mass fraction;

[0060] The preparation method of the octadecylamine modified titanium white powder is: titanium white powder is added into silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 80℃ for 6h, then centrifuged, washed and dried to obtain powder A; powder A is added into 20g / L octadecylamine ethanol solution and uniformly dispersed, stirred and reacted at 60℃ for 12h, then centrifuged, washed and dried, wherein the mass ratio of titanium white powder to silane coupling agent KH-560 is 1:3, the mass ratio of powder A to octadecylamine is 1:10, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:10:5;

[0061] The raw material of the core layer consists of 85 parts of polypropylene, 15 parts of pearlescent masterbatch and 2 parts of antistatic agent by mass fraction; the raw material of the pearlescent masterbatch consists of 80 parts of polypropylene, 20 parts of octadecylamine modified calcium carbonate, 2 parts of dispersant and 1 part of antioxidant by mass fraction;

[0062] The preparation method of the octadecylamine modified calcium carbonate is: calcium carbonate is added into silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 80℃ for 6h, then centrifuged, washed and dried to obtain powder B; powder B is added into 20g / L octadecylamine ethanol solution and uniformly dispersed, stirred and reacted at 60℃ for 12h, then centrifuged, washed and dried, wherein the mass ratio of calcium carbonate to silane coupling agent KH-560 is 1:3, the mass ratio of powder B to octadecylamine is 1:10, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:10:5;

[0063] The raw material of the sub-under-layer is polypropylene;

[0064] The raw material of the lower layer consists of 90 parts of polypropylene and 10 parts of anti-blocking masterbatch by mass fraction; the raw material of the anti-blocking masterbatch consists of 95 parts of polypropylene, 5 parts of glass microbeads, 1 part of dispersant and 1 part of antioxidant by mass fraction, wherein the particle size of the glass microbeads is 3-5μm.

[0065] The total thickness of the above-mentioned pearl label film is 46μm, the thickness of the upper layer is 2.5μm, the thickness of the sub-upper layer is 6μm, the thickness of the core layer is 30μm, the thickness of the sub-under-layer is 6μm, and the thickness of the lower layer is 1.5μm.

[0066] The preparation method of the above-mentioned pearl label film is the same as that of Example 1.

[0067] Comparative Example 1

[0068] A pearl label film is a BOPP film with a five-layer structure, which comprises an upper layer, a sub-upper layer, a core layer, a sub-under-layer and a lower layer in sequence;

[0069] The raw material of the upper surface layer is a matting agent;

[0070] The raw material of the sub-upper surface layer consists of 85 parts of polypropylene and 15 parts of a whitening masterbatch by mass; the raw material of the whitening masterbatch consists of 70 parts of polypropylene, 30 parts of titanium dioxide modified by silane coupling agent KH-560, 1.5 parts of a dispersing agent and 0.5 parts of an antioxidant by mass;

[0071] The preparation method of the titanium dioxide modified by silane coupling agent KH-560 is as follows: the titanium dioxide is added into a silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 50℃ for 3h, then centrifuged, washed and dried, and the titanium dioxide modified by silane coupling agent KH-560 is obtained, wherein the mass ratio of the titanium dioxide to the silane coupling agent KH-560 is 1:2, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:6:4;

[0072] The raw material of the core layer consists of 80 parts of polypropylene, 20 parts of a pearl masterbatch and 1 part of an antistatic agent by mass; the raw material of the pearl masterbatch consists of 70 parts of polypropylene, 30 parts of calcium carbonate modified by silane coupling agent KH-560, 1.5 parts of a dispersing agent and 0.5 parts of an antioxidant by mass;

[0073] The preparation method of the calcium carbonate modified by silane coupling agent KH-560 is as follows: the calcium carbonate is added into a silane coupling agent KH-560 solution and uniformly dispersed, stirred and reacted at 50℃ for 3h, then centrifuged, washed and dried, and the calcium carbonate modified by silane coupling agent KH-560 is obtained, wherein the mass ratio of the calcium carbonate to the silane coupling agent KH-560 is 1:2, and the silane coupling agent KH-560 solution is obtained by mixing silane coupling agent KH-560, anhydrous ethanol and water at a mass ratio of 1:6:4;

[0074] The raw material of the sub-lower surface layer is polypropylene;

[0075] The raw material of the lower surface layer consists of 85 parts of polypropylene and 15 parts of an anti-blocking masterbatch by mass; the raw material of the anti-blocking masterbatch consists of 92 parts of polypropylene, 8 parts of glass microbeads, 0.5 parts of a dispersing agent and 0.5 parts of an antioxidant by mass, wherein the particle size of the glass microbeads is 3-5μm.

[0076] The total thickness of the above-mentioned pearl label film is 46μm, the thickness of the upper surface layer is 2.5μm, the thickness of the sub-upper surface layer is 6μm, the thickness of the core layer is 30μm, the thickness of the sub-lower surface layer is 6μm, and the thickness of the lower surface layer is 1.5μm.

[0077] The preparation method of the above-mentioned pearl label film is the same as that of Example 1.

[0078] Test Example

[0079] The crease length of the pearl label film after winding in Example 1 and Comparative Example 1 (the film roll is 6000 m) was tested, and the performance of the pearl label films prepared in Example 1 and Comparative Example 1 was tested, wherein the tensile strength test was performed according to GB / T1040.3-2006, and the haze test was performed according to GB / T 2410-2008; the test results are shown in Table 1:

[0080] Table 1

[0081]

[0082]

[0083] As shown in Table 1, the pearl label films prepared in Examples 1-3 have excellent mechanical properties and appearance effects, and are not prone to wrinkling, and can significantly improve the yield and product quality of the film, because in Examples 1-3, the whitening agent and pearl powder are added to the sub-surface layer and the core layer, respectively, and the titanium dioxide as the whitening agent and the calcium carbonate as the pearl powder are modified, the epoxy silane coupling agent KH-560 is first grafted on the surface, and then the octadecylamine is grafted to the surface of the powder through the action between the amine group and the epoxy group, so that a long aliphatic chain with good flexibility is grafted on the surface of the powder, which can improve the dispersibility of titanium dioxide and calcium carbonate in the functional layer, thereby improving the uniformity of the film functional layer composition, and can also improve the flexibility of the film, thereby effectively improving the wrinkling phenomenon of the film during processing and use; in Comparative Example 1, the epoxy silane coupling agent KH-560 is grafted on the surface of titanium dioxide and calcium carbonate, which can improve the compatibility between the powder and the film substrate, but the effect of improving flexibility is not good, and the wrinkling phenomenon is much more serious than that of the films of Examples 1-3.

[0084] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A pearl label film, characterized in that, The pearl label film is a five-layer BOPP film, which includes, in sequence, an upper surface layer, a second upper surface layer, a core layer, a second lower surface layer, and a lower surface layer. The raw material for the upper surface layer includes matte material; The raw materials of the sub-top layer include 80-90 parts of polypropylene and 10-20 parts of whitening masterbatch by weight; the raw materials of the whitening masterbatch include 60-80 parts of polypropylene, 20-40 parts of octadecylamine-modified titanium dioxide, 1-2 parts of dispersant, and 0.5-1 parts of antioxidant by weight. The preparation method of the octadecylamine-modified titanium dioxide includes: dispersing titanium dioxide in a silane coupling agent KH-560 solution, stirring and reacting at 40-80°C for 2-6 hours, then centrifuging, washing, and drying to obtain powder A; dispersing powder A in an ethanol solution of octadecylamine, stirring and reacting at 40-60°C for 5-12 hours, then centrifuging, washing, and drying to obtain the final product; the mass ratio of titanium dioxide to silane coupling agent KH-560 is 1:1-3; the mass ratio of powder A to octadecylamine is 1:1-10. The raw materials of the core layer include, by weight, 70-85 parts of polypropylene, 15-30 parts of pearlescent masterbatch, and 0.5-2 parts of antistatic agent; the raw materials of the pearlescent masterbatch include, by weight, 60-80 parts of polypropylene, 20-40 parts of octadecylamine-modified calcium carbonate, 1-2 parts of dispersant, and 0.5-1 parts of antioxidant. The preparation method of the octadecylamine-modified calcium carbonate includes: dispersing calcium carbonate evenly in a silane coupling agent KH-560 solution, stirring and reacting at 40-80°C for 2-6 hours, then centrifuging, washing, and drying to obtain powder B; dispersing the powder B evenly in an ethanol solution of octadecylamine, stirring and reacting at 40-60°C for 5-12 hours, then centrifuging, washing, and drying to obtain the final product; the mass ratio of calcium carbonate to silane coupling agent KH-560 is 1:1-3; the mass ratio of powder B to octadecylamine is 1:1-10. The raw material for the lower sublayer includes polypropylene; The raw materials of the lower surface layer include 80-90 parts by weight of polypropylene and 10-20 parts by weight of anti-blocking masterbatch.

2. The pearl label film according to claim 1, characterized in that, The raw materials of the anti-blocking masterbatch include, by weight, 90-95 parts polypropylene, 5-10 parts glass microspheres, 0.5-1 parts dispersant, and 0.2-1 parts antioxidant; the particle size of the glass microspheres is 3-5 μm.

3. The pearl label film according to claim 1, characterized in that, The dispersant is at least one of stearic acid, sodium stearate, calcium stearate, and erucamide; the antioxidant is antioxidant 1010, antioxidant 168, or a combination thereof.

4. The pearl label film according to claim 1, characterized in that, The total thickness of the pearl label film is 35-55 μm, the thickness of the upper surface layer is 2-3 μm, the thickness of the second upper surface layer is 5-8 μm, the thickness of the core layer is 15-35 μm, the thickness of the second lower surface layer is 5-7 μm, and the thickness of the lower surface layer is 1-2 μm.

5. A method for preparing a pearl label film as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. The raw materials of the upper surface layer, the second upper surface layer, the core layer, the second lower surface layer and the lower surface layer are melted and extruded to obtain the upper surface layer melt, the second upper surface layer melt, the core layer melt, the second lower surface layer melt and the lower surface layer melt. The melt is then co-extruded through a five-layer die head and cooled with a chilling roller to obtain a thick sheet. S2. The thick sheet is stretched longitudinally and then stretched laterally, then cooled and wound up to obtain a pearl label film.

6. The method for preparing the pearl label film according to claim 5, characterized in that, In S1, the melt extrusion temperature is 220–230℃; In S1, the cooling temperature is 30–35°C; In S2, the longitudinal stretching temperature is 110–130℃ and the stretching ratio is 5–6; the transverse stretching temperature is 160–180℃ and the stretching ratio is 8–9.

Images