In-mold label

Abstract

The invention discloses an in-mold label, which comprises a polypropylene base material layer and a polyethylene lamination layer, and the polyethylene lamination layer is arranged on the polypropylene base material layer. The polypropylene base material layer comprises a propylene homopolymer, a first petroleum resin and an inorganic filler, and the content of the first petroleum resin is 2-20 weight percent based on the total weight of the polypropylene base material layer as 100 weight percent.

Description

Technical Field

[0001] The present application relates to an in-mold label, and more particularly to an in-mold label with high stiffness and capable of high-speed production. Background Art

[0002] In-mold label is an object used for in-mold decoration technology. In the manufacturing process of plastic containers, the in-mold label can be integrally formed with the plastic container, so that the final plastic container is decorated with an in-mold label with a printed pattern.

[0003] During the manufacturing process, the glued label is sent to a fixed point in the mold and fixed by adsorption. Then, the plastic container is formed by injection molding, blow molding, differential pressure molding or foam molding. At this time, the in-mold label is integrally formed with the plastic container, and the in-mold label is decorated on the outer surface of the plastic container.

[0004] Plastic containers made with in-mold decoration technology have excellent appearance, but compared with traditional film or transfer methods, in-mold decoration technology takes longer and costs more. If the production rate of in-mold labels can be increased, the production cost of in-mold labels can be reduced. Therefore, in order to cope with high-speed manufacturing processes, in-mold labels must have sufficient stiffness to withstand high-speed production processes.

[0005] In addition, most of the container materials currently used in the market are polypropylene, but the existing in-mold label materials are not polypropylene. Due to the difference in materials, the used plastic containers cannot be directly recycled, which leads to complicated processing problems.

[0006] Therefore, how to improve the stiffness of in-mold labels through structural design improvements to solve the problem of low production rate of in-mold labels in the past and improve the problem that plastic containers made using in-mold decoration technology cannot be directly recycled has become one of the important issues that this business wants to solve. Summary of the invention

[0007] The technical problem to be solved by the present application is to provide an in-mold label to address the deficiencies of the prior art.

[0008] In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide an in-mold label. The in-mold label includes a polypropylene substrate layer and a polyethylene coating layer, and the polyethylene coating layer is arranged on the polypropylene substrate layer. The polypropylene substrate layer contains a propylene homopolymer, a first petroleum resin and an inorganic filler, and the total weight of the polypropylene substrate layer is 100 weight percent, and the content of the first petroleum resin is 2 weight percent to 20 weight percent.

[0009] Furthermore, the first petroleum resin is a hydrogenated petroleum resin having 5 or 9 carbon atoms.

[0010] Furthermore, taking the total weight of the polypropylene substrate layer as 100 weight percent, the content of the propylene homopolymer is 75 weight percent to 92 weight percent, and the content of the inorganic filler is 5 weight percent to 12 weight percent.

[0011] Furthermore, the polyethylene coating layer includes an ethylene polymer and a second petroleum resin.

[0012] Furthermore, with the total weight of the polyethylene coating layer being 100 weight percent, the polyethylene coating layer includes 2 weight percent to 5 weight percent of the second petroleum resin.

[0013] Furthermore, the second petroleum resin is selected from the group consisting of hydrogenated rosin, hydrogenated petroleum resin polymerized from monomers having 5 carbon atoms, and hydrogenated petroleum resin polymerized from monomers having 9 carbon atoms.

[0014] Furthermore, the added weight of the first petroleum resin is 1 to 4 times the added weight of the second petroleum resin.

[0015] Furthermore, the ethylene polymer is a low-density polyethylene, and the ethylene polymer comprises 30 to 80 weight percent of a linear low-density polyethylene based on the total amount of the ethylene polymer as 100 weight percent.

[0016] Furthermore, the in-mold label further comprises: an outer surface layer and an inner surface layer, the polypropylene substrate layer is arranged between the outer surface layer and the inner surface layer, and the polyethylene coating layer is arranged on the inner surface layer.

[0017] Furthermore, the material of the outer surface layer is selected from binary copolymer polypropylene, ternary copolymer polypropylene and a combination thereof, and the material of the inner surface layer is selected from binary copolymer polypropylene, ternary copolymer polypropylene and a combination thereof.

[0018] One of the beneficial effects of the present invention is that the in-mold label provided by the present invention can achieve the effect of improving the Young's modulus, elongation, shrinkage and peel strength of the in-mold label through the technical scheme of "the polypropylene substrate layer includes a propylene homopolymer, a first petroleum resin and an inorganic filler" and "the total weight of the polypropylene substrate layer is 100 weight percent, and the content of the first petroleum resin is 2 weight percent to 20 weight percent". In this way, the in-mold label of the present invention can be applied to high-speed production processes and can be well combined with plastic containers.

[0019] To further understand the features and technical contents of the present application, please refer to the following detailed description and drawings of the present application. However, the drawings provided are only for reference and illustration and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. 1 is a schematic side view of an in-mold label according to a first embodiment of the present invention.

[0021] Figure 2 FIG. 4 is a side view of an in-mold label according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following is an explanation of the implementation methods of the "in-mold label" disclosed in the present invention through specific examples. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted in actual size. It is stated in advance. The following implementation methods will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used in this article may include any one or more combinations of the associated listed items depending on the actual situation.

[0023] In order to solve the problem that plastic containers cannot be directly recycled in the past, the present invention uses polypropylene material and develops materials for in-mold labels.

[0024] In order to increase the production speed of the in-mold label, the present invention selects a specific material with a large shrinkage and elongation, which is conducive to application in a high-speed injection manufacturing process, thereby increasing the production speed of the in-mold label.

[0025] The in-mold label of the present invention has high stiffness. Therefore, during the bonding process, the air between the in-mold label and the plastic container can be effectively removed, and no bubbles will be formed on the in-mold label. In addition, the high stiffness of the in-mold label can make the in-mold label be formed evenly on the outer surface of the plastic container without the problem of unstable bonding.

[0026] In the present invention, the stiffness of the in-mold label is quantitatively expressed by Young's modulus. It is worth noting that the in-mold label of the present invention is not made by a coating process, but by an injection method.

[0027] [First embodiment]

[0028] See also Figure 1 As shown, the in-mold label Z of the present invention comprises at least a polypropylene substrate layer 1 and a polyethylene coating layer 2. The polyethylene coating layer 2 can be formed on the polypropylene substrate layer 1 by coating. Moreover, the polypropylene substrate layer 1 and the polyethylene coating layer 2 are integrally formed.

[0029] The polypropylene substrate layer has good stiffness and is the main structure of the in-mold label. The material of the polypropylene substrate layer includes a propylene homopolymer, an inorganic filler and a first petroleum resin. The composite material system formed by mixing the propylene homopolymer, the inorganic filler and the first petroleum resin has an important influence on the stiffness of the in-mold label.

[0030] Compared with binary copolymer polypropylene, ternary copolymer polypropylene or other types of propylene polymers, propylene homopolymer has a regular structure and better crystallinity. Therefore, using propylene homopolymer as the main material of the polypropylene substrate layer can effectively improve the stiffness of the in-mold label.

[0031] The addition of inorganic fillers can also improve the stiffness of the polypropylene substrate layer. For example, the inorganic filler can be calcium carbonate, which has the effect of supporting the polypropylene substrate layer. In addition, calcium carbonate can make the polypropylene substrate layer have a white appearance, which is convenient for printing on the in-mold label, but the present invention is not limited thereto.

[0032] However, inorganic fillers are inorganic materials, and propylene homopolymers are organic materials. The two materials cannot be evenly mixed. During the drawing step, pores will be generated between the inorganic fillers and the propylene homopolymer, resulting in a decrease in the density and stiffness of the in-mold label. For example, the density of the in-mold label can be 0.7g / cm 3 Up to 0.8g / cm 3 .

[0033] In order to solve the problem of reduced stiffness of the in-mold label due to reduced density after the drawing step, the present invention adds an appropriate amount of the first petroleum resin.

[0034] The addition of the first petroleum resin can help disperse the inorganic filler in the propylene homopolymer and improve the affinity between the propylene homopolymer and the inorganic filler, thereby achieving the effect of improving the stiffness (Young's modulus) of the propylene substrate layer and improving the bonding strength (peel strength) between the propylene substrate layer and the polyethylene coating layer.

[0035] In addition, the addition of the first petroleum resin can also improve the elongation of the material, making the in-mold label suitable for high-speed production processes. For example, the manufacturing process can produce 150 in-mold labels per minute, which is a production rate that cannot be achieved in the prior art.

[0036] When the first petroleum resin is a saturated resin, the addition of the first petroleum resin can effectively improve the Young's modulus of the polypropylene substrate layer. The specific Young's modulus data of the in-mold label will be described later. The softening point of the first petroleum resin is 100°C to 150°C, preferably, the softening point of the first petroleum resin is 135°C to 145°C, but the present invention is not limited thereto.

[0037] Specifically, the first petroleum resin is preferably a saturated petroleum resin polymerized from a monomer having a carbon number of 5 or a saturated petroleum resin polymerized from a monomer having a carbon number of 9. For example, the first petroleum resin may be a hydrogenated isoprene resin or a hydrogenated dicyclopentadiene (DCPD) resin. Alternatively, the first petroleum resin may also be a water-white thermoplastic resin obtained by polymerization and hydrogenation of a C9 fraction, a byproduct of ethylene cracking.

[0038] In an exemplary embodiment, the total weight of the polypropylene substrate layer is 100 weight percent, the content of the first petroleum resin is 1 weight percent to 20 weight percent, the content of the inorganic filler is 5 weight percent to 12 weight percent, and the content of the propylene homopolymer is 75 weight percent to 92 weight percent.

[0039] Preferably, with the total weight of the polypropylene substrate layer being 100 weight percent, the content of the first petroleum resin is 1 weight percent to 15 weight percent, the content of the inorganic filler is 7 weight percent to 12 weight percent, and the content of the propylene homopolymer is 78 weight percent to 92 weight percent.

[0040] The in-mold label is attached to the plastic container through a polyethylene coating layer. Therefore, the polyethylene coating layer made of a specific material can help to set a smooth in-mold label on the surface of the plastic container.

[0041] In the present invention, the polyethylene coating layer can replace the hot melt adhesive used in the conventional in-mold label, eliminating the coating process used in the conventional hot melt adhesive, and has the advantage of an environmentally friendly manufacturing process.

[0042] In order to replace the hot melt adhesive used in the past, the material of the polyethylene coating layer is mainly composed of ethylene polymer. Specifically, the ethylene polymer includes low-density polyethylene, and the low-density polyethylene includes linear low-density polyethylene. The melt index of the ethylene polymer is 5 to 10, preferably 6 to 8, and more preferably 7.

[0043] In an exemplary embodiment, the total amount of the ethylene polymer is 100 weight percent, and the ethylene polymer includes 30 weight percent to 80 weight percent of linear low-density polyethylene. In this way, the in-mold label can have a better bonding force with the container (reflected in the peel strength). However, the present invention is not limited thereto.

[0044] In an exemplary embodiment, the material of the polyethylene coating layer may further include a second petroleum resin. The addition of the second petroleum resin can enhance the bonding between the polyethylene coating layer and the polypropylene substrate layer, and between the polyethylene coating layer and the plastic container.

[0045] Preferably, the second petroleum resin is a saturated petroleum resin. For example, the second petroleum resin is selected from the group consisting of hydrogenated rosin, hydrogenated petroleum resin polymerized from monomers having a carbon number of 5, and hydrogenated petroleum resin polymerized from monomers having a carbon number of 9. Specifically, the second petroleum resin may be a hydrogenated isoprene resin or a hydrogenated dicyclopentadiene (DCPD) resin. The second petroleum resin may also be a water-white thermoplastic resin obtained by polymerization and hydrogenation of a C9 fraction, a byproduct of ethylene cracking, but the present invention is not limited thereto.

[0046] Taking the total weight of the polyethylene coating layer as 100 weight percent, the content of the ethylene polymer is 90 weight percent to 98 weight percent, and the content of the second petroleum resin is 2 weight percent to 5 weight percent.

[0047] By adding the first petroleum resin and the second petroleum resin, the shrinkage and elongation of the material are increased, which is beneficial to the high-speed injection production of the in-mold label. In addition, the in-mold label has a higher Young's modulus and peel strength.

[0048] In an exemplary embodiment, the added weight of the first petroleum resin is 1 to 4 times the added weight of the second petroleum resin. Preferably, the added weight of the first petroleum resin is 1 to 2 times the added weight of the second petroleum resin. By adjusting the added weight ratio of the first petroleum resin to the second petroleum resin, the effect of taking into account the Young's modulus and peel strength of the in-mold label can be achieved.

[0049] [Second embodiment]

[0050] See also Figure 2As shown, in the second embodiment, in addition to the polypropylene substrate layer 1 and the polyethylene coating layer 2, the in-mold label Z further includes an outer surface layer 3 and an inner surface layer 4. The polypropylene substrate layer 1 is sandwiched between the outer surface layer 3 and the inner surface layer 4, and the polyethylene coating layer 2 is disposed on the inner surface layer 4. The polypropylene substrate layer 1 and the polyethylene coating layer 2 of the second embodiment are similar to those of the first embodiment, and therefore will not be described in detail herein.

[0051] Specifically, the outer layer 3, the polypropylene substrate layer 1, the inner layer 4 and the polyethylene coating layer 2 are integrally formed. Moreover, the outer layer 3, the polypropylene substrate layer 1 and the inner layer 4 can form a structure similar to pearl paper, and the outer layer 3 can be printed with text or patterns.

[0052] The material of the outer layer may include binary copolymer polypropylene, ternary copolymer polypropylene or a combination thereof. Thus, the outer layer can have a good bonding effect with the polypropylene substrate layer, and the in-mold label is suitable for a high-speed injection manufacturing process.

[0053] In an exemplary embodiment, the material of the outer layer is selected from binary copolymer polypropylene, terpolymer polypropylene and a combination thereof. More preferably, the material of the outer layer is composed of binary copolymer polypropylene and terpolymer polypropylene.

[0054] Preferably, the melting point of the material of the outer layer is 140° C. to 150° C., preferably 142° C. to 148° C., and more preferably 143° C. to 145° C. The material of the outer layer has a melt index of 2 to 5, preferably 2 to 4.

[0055] The material of the inner surface layer may include binary copolymer polypropylene, ternary copolymer polypropylene or a combination thereof. Thus, the inner surface layer can have a good bonding effect with the polypropylene substrate layer, and the in-mold label is suitable for a high-speed injection manufacturing process.

[0056] In an exemplary embodiment, the material of the inner surface layer is selected from binary copolymer polypropylene, terpolymer polypropylene and a combination thereof. More preferably, the material of the inner surface layer is composed of binary copolymer polypropylene and terpolymer polypropylene.

[0057] Preferably, the melting point of the material of the inner surface layer is 140° C. to 150° C., preferably 142° C. to 148° C., and more preferably 143° C. to 145° C. The material of the inner surface layer has a melt index of 2 to 5, preferably 2 to 4.

[0058] The binary copolymer polypropylene in the outer layer and the inner layer is polymerized from propylene monomer and ethylene monomer, and the ternary copolymer polypropylene in the outer layer and the inner layer is polymerized from propylene monomer, ethylene monomer and butene monomer. According to experimental tests, the outer layer and the inner layer made of the above materials, the in-mold label can be suitable for the high-speed injection manufacturing process.

[0059] [Experimental data]

[0060] In order to verify that the in-mold label of the present invention has better stiffness, elongation and bonding properties, in-mold labels of Comparative Example 1 and Experimental Examples 1 to 3 were prepared according to the structure of the second embodiment.

[0061] [Experimental Examples 1 to 3]

[0062] First, prepare materials for forming the outer surface layer, polypropylene substrate layer, inner surface layer and polyethylene coating layer. The materials of the outer surface layer and the inner surface layer are binary copolymer polypropylene and ternary copolymer polypropylene, wherein the added weight of the binary copolymer polypropylene is 4.5 to 5.5 times the added weight of the ternary copolymer polypropylene. The materials of the polypropylene substrate layer include propylene homopolymer, isoprene hydrogenated resin, dicyclopentadiene hydrogenated resin and calcium carbonate. The material of the polyethylene coating layer is low-density polyethylene, and the low-density polyethylene includes linear low-density polyethylene. The specific added weight of each component and the weight percentage in each layer are listed in Table 1.

[0063] The above materials are used to prepare an in-mold label consisting of an outer layer, a polypropylene substrate layer, an inner layer and a polyethylene coating layer by injection molding. The thickness of the in-mold label is 100 microns to 200 microns, so that the in-mold label has better stiffness. Preferably, the thickness of the in-mold label is preferably 155 microns to 190 microns. Among them, the thickness of the polyethylene coating layer is 10 microns to 20 microns, and the thickness of the polyethylene coating layer is preferably 10 microns to 15 microns. In this way, the in-mold label is conveniently set on the plastic container.

[0064] The manufactured in-mold label was tested for Young's modulus, tensile strength, elongation, shrinkage and peel strength, and the results are listed in Table 1.

[0065] The Young's modulus, tensile strength and elongation of the in-mold label are obtained by testing with a tensile testing machine in accordance with the ASTM D882 standard set by the American Society for Testing and Materials (ASTM).

[0066] The shrinkage rate of the in-mold label is obtained by placing the in-mold label in an oven at 130°C for 15 minutes, and measuring its length change after cooling. The peel strength of the in-mold label is measured by molding the in-mold label on a polypropylene container bottle.

[0067] [Comparative Example 1]

[0068] The method for preparing the in-mold label in Comparative Example 1 is similar to that in Experimental Examples 1 to 3, with the main difference being that the first petroleum resin is not added to the polypropylene substrate layer, and the second petroleum resin is not added to the polyethylene coating layer. The specific added weight parts of each component in Comparative Example 1 and the weight percentage in each layer are listed in Table 1, and the rest of the parts not specifically described are similar to Experimental Examples 1 to 3.

[0069] The thickness of the in-mold label of Comparative Example 1 is 100 μm to 200 μm, and the thickness of the polyethylene coating layer is 10 μm to 20 μm. After the in-mold label of Comparative Example 1 is manufactured, the Young's modulus, tensile strength, elongation, shrinkage and peel strength are tested according to the above method, and the results are listed in Table 1.

[0070] Table 1

[0071]

[0072]

[0073] It can be seen from the experimental results that the in-mold label of the present invention can have a higher Young's modulus, higher elongation, higher shrinkage and higher peel strength after adding the first petroleum resin and the second petroleum resin.

[0074] The characteristics of high elongation and high shrinkage make the in-mold label of the present invention applicable to high-speed production processes. The characteristics of high Young's modulus and high peel strength make the in-mold label of the present invention have better stiffness, are more suitable for processing, and can be well combined with plastic containers.

[0075] It can be seen from the experimental results that when the content of the first petroleum resin is increased, the Young's modulus of the polypropylene substrate layer can be increased.

[0076] However, in actual operation, the Young's modulus of the in-mold label does not need to be so high, and can be applied to high-speed production processes. Therefore, with the total weight of the polypropylene substrate layer as 100 weight percent, the content of the first petroleum resin can be 3 weight percent, 4 weight percent, 5 weight percent, 6 weight percent, 7 weight percent, 8 weight percent, 9 weight percent, 10 weight percent, 11 weight percent, 12 weight percent, 13 weight percent or 14 weight percent. With the total weight of the polyethylene coating layer as 100 weight percent, the content of the second petroleum resin can be 2 weight percent, 3 weight percent, 4 weight percent or 5 weight percent.

[0077] From the results in Table 1, it can be seen that the Young's modulus of the in-mold label in the longitudinal direction (MD) is greater than 120 kg / mm 2 Specifically, the Young's modulus of the in-mold label in the longitudinal direction is 121kg / mm 2 Up to 160kg / mm 2 The Young's modulus of the in-mold label in the transverse direction (TD) is greater than 125kg / mm 2 Specifically, the Young's modulus of the in-mold label in the transverse direction is 128kg / mm 2 Up to 150kg / mm 2 .

[0078] From the results in Table 1, it can be seen that the tensile strength of the in-mold label in the longitudinal direction (MD) is 1700 kg / mm 2 Up to 2000kg / mm 2 Preferably, the tensile strength of the in-mold label in the longitudinal direction is 1730kg / mm 2 Up to 1950kg / mm 2 The tensile strength of the in-mold label in the transverse direction (TD) is 1500kg / mm 2 Up to 2300kg / mm 2 Specifically, the tensile strength of the in-mold label in the transverse direction is 1600kg / mm 2 Up to 2200kg / mm 2 .

[0079] From the results in Table 1, it can be seen that the elongation of the in-mold label in the longitudinal direction (MD) is greater than 96%, specifically, the elongation of the in-mold label in the longitudinal direction is 97% to 112%. The elongation of the in-mold label in the transverse direction (TD) is greater than 70%, specifically, the elongation of the in-mold label in the transverse direction is 100% to 135%.

[0080] It can be seen from the results in Table 1 that the shrinkage rate of the in-mold label is greater than 2.5%. Specifically, the shrinkage rate of the in-mold label is 3% to 5%.

[0081] It can be seen from the results in Table 1 that the peel strength of the in-mold label is greater than 5N / 15mm. Specifically, the peel strength of the in-mold label is 6N / 15mm to 9N / 15mm.

[0082] [Beneficial Effects of Embodiments]

[0083] One of the beneficial effects of the present invention is that the in-mold label provided by the present invention can achieve the effect of improving the Young's modulus, elongation, shrinkage and peel strength of the in-mold label through the technical scheme of "the polypropylene substrate layer includes a propylene homopolymer, a first petroleum resin and an inorganic filler" and "the total weight of the polypropylene substrate layer is 100 weight percent, and the content of the first petroleum resin is 2 weight percent to 20 weight percent". In this way, the in-mold label of the present invention can be applied to high-speed production processes and can be well combined with plastic containers.

[0084] Furthermore, when saturated resin (hydrogenated petroleum resin with carbon number 5 and hydrogenated petroleum resin with carbon number 9) is selected as the first petroleum resin, it can help disperse the inorganic filler in the propylene homopolymer to improve the affinity between the propylene homopolymer and the inorganic filler, thereby improving the bonding force between the propylene substrate layer and the polyethylene coating layer, and improving the stiffness of the in-mold label. In addition, the addition of the first petroleum resin can also increase the elongation of the material, making the in-mold label suitable for high-speed production manufacturing processes.

[0085] The contents disclosed above are only preferred feasible embodiments of the present application, and are not intended to limit the protection scope of the claims of the present application. Therefore, all equivalent technical changes made using the contents of the present application specification and drawings are included in the protection scope of the claims of the present application.

Claims

1. An in-mold label, characterized in that: The in-mold label comprises: a polypropylene substrate layer, the polypropylene substrate layer comprising a propylene homopolymer, a first petroleum resin and an inorganic filler, wherein the content of the first petroleum resin is 1 to 20 weight percent based on the total weight of the polypropylene substrate layer as 100 weight percent; and A polyethylene coating layer is disposed on the polypropylene substrate layer.

2. The in-mold label according to claim 1, characterized in that: The first petroleum resin is a hydrogenated petroleum resin obtained by polymerizing a monomer having 5 carbon atoms or a hydrogenated petroleum resin obtained by polymerizing a monomer having 9 carbon atoms.

3. The in-mold label according to claim 1, characterized in that: Taking the total weight of the polypropylene substrate layer as 100 weight percent, the content of the propylene homopolymer is 75 weight percent to 92 weight percent, and the content of the inorganic filler is 5 weight percent to 12 weight percent.

4. The in-mold label according to claim 1, characterized in that: The polyethylene coating layer includes an ethylene polymer and a second petroleum resin.

5. The in-mold label according to claim 4, characterized in that: Taking the total weight of the polyethylene coating layer as 100 weight percent, the polyethylene coating layer includes 2 weight percent to 5 weight percent of the second petroleum resin.

6. The in-mold label according to claim 4, characterized in that: The second petroleum resin is selected from the group consisting of hydrogenated rosin, hydrogenated petroleum resin polymerized from monomers having 5 carbon atoms, and hydrogenated petroleum resin polymerized from monomers having 9 carbon atoms.

7. The in-mold label according to claim 4, characterized in that: The added weight of the first petroleum resin is 1 to 4 times the added weight of the second petroleum resin.

8. The in-mold label according to claim 4, characterized in that: The ethylene polymer is low-density polyethylene. Taking the total amount of the ethylene polymer as 100 weight percent, the ethylene polymer comprises 30 weight percent to 80 weight percent of linear low-density polyethylene.

9. The in-mold label according to claim 1, characterized in that: The in-mold label further comprises: an outer surface layer and an inner surface layer, the polypropylene substrate layer is arranged between the outer surface layer and the inner surface layer, and the polyethylene coating layer is arranged on the inner surface layer.

10. The in-mold label according to claim 9, characterized in that: The material of the outer surface layer is selected from binary copolymer polypropylene, ternary copolymer polypropylene and a combination thereof, and the material of the inner surface layer is selected from binary copolymer polypropylene, ternary copolymer polypropylene and a combination thereof.

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