Polyolefin material with soft surface performance for film covering as well as preparation method and application of polyolefin material

Abstract

The invention relates to the field of packaging, in particular to a polyolefin material for a film with soft surface performance as well as a preparation method and application of the polyolefin material. The polyolefin material is in a film shape and comprises three layers from outside to inside: a surface layer is a modified heat-resistant layer and is composed of polypropylene homopolymer resin and a polypropylene modification additive; the middle layer is a supporting layer and consists of homo-polypropylene resin and polypropylene homo-polypropylene resin; and the inner layer is a thermal bonding sealing layer and consists of polypropylene copolymer resin, an n-butenyl olefin copolymer and an additive. Through special functional formula design and a multi-layer co-extrusion casting processing technology, the polyolefin film which is good in ductility and particularly suitable for irregular article film covering requirements is obtained, and the problems that an existing BOPP or BOPET material pre-coating film is large in rigidity and poor in ductility, and the attaching effect is poor during irregular article film covering can be solved.

Description

Technical Field

[0001] The invention relates to the field of packaging, and in particular to a polyolefin material for film coating with soft surface performance, and a preparation method and application thereof. Background Art

[0002] Pre-coated film is a laminated product composed of a hot melt adhesive layer and a film substrate. Its production process is to coat the film material (BOPP, BOPET) with hot melt adhesive under specific production process conditions, cool and shape it, and then process it into a finished product that meets the size requirements of the packaging laminated product through a slitting machine. When in use, the product can be laminated by heating and pressurizing it through a laminating machine.

[0003] The main market applications of pre-coated films are industrial pre-coated films and commercial pre-coated films. The industrial market mainly includes the lamination market for publications, printed materials, and packaging of consumer goods such as food, medicine, and daily necessities; the commercial market mainly includes the lamination market for applications in emerging fields such as digital printing, cards, anti-counterfeiting, commercial advertising, and building materials.

[0004] With the promotion and development of the application of pre-coated films, many emerging markets for special purposes have been spawned. Pre-coated films produced using traditional BOPP (biaxially oriented polypropylene film) and BOPET (biaxially oriented polyester film) as basic materials have disadvantages and shortcomings in some special emerging markets. Due to the high rigidity and poor ductility of traditional pre-coated films, it is difficult to achieve and be competent for post-processing lamination on some irregular products.

[0005] Therefore, it is necessary to improve the existing pre-coated films to meet the coating needs of irregular items in the special-purpose market. Summary of the invention

[0006] In order to solve the problems in the prior art, one of the purposes of the present invention is to provide a polyolefin material for lamination with soft surface performance, and to solve the problems of existing BOPP or BOPET pre-coated films, such as high rigidity, poor ductility, and poor adhesion to irregular objects when laminating, by optimizing the formula of modified polyolefin films.

[0007] The present invention adopts the following technical solutions:

[0008] A polyolefin material for laminating with soft surface performance, the polyolefin material is in the form of a film, and comprises three layers from the outside to the inside:

[0009] The surface layer is a modified heat-resistant layer with a thickness of 20 to 24 μm, composed of 99.5 wt% polypropylene homopolymer resin and 0.5 wt% polypropylene modified additive;

[0010] The middle layer is a support layer, with a thickness of 38 to 42 μm, and is composed of 60 wt% homopolymer polypropylene resin and 40 wt% polypropylene homopolymer resin;

[0011] The inner layer is a heat-bonding sealing layer with a thickness of 16-20 μm and is composed of (42-48) wt% polypropylene copolymer resin, (47-53) wt% n-butene olefin copolymer and 5 wt% additives.

[0012] Preferably, the polypropylene modification aid is a rigidity-enhancing nucleating agent, and the additives include an open masterbatch and a smooth masterbatch in a mass ratio of 3:2.

[0013] Preferably, the polypropylene homopolymer resin is HD915CF, the homopolymer polypropylene resin is FC801, the polypropylene copolymer resin is FL7642, the n-butene olefin copolymer is BL2491M, the rigidity enhancing nucleating agent is NA-27, the open masterbatch is ABPP 10S, and the slip masterbatch is SLPP-7.

[0014] Preferably, the total thickness of the polyolefin material is 70-90 μm.

[0015] Preferably, the polyolefin material has a thickness of 80 μm, the surface layer has a thickness of 22 μm, the middle layer has a thickness of 40 μm, and the inner layer has a thickness of 12 μm.

[0016] The second object of the present invention is to provide a method for preparing a polyolefin material for coating with soft surface performance as described above, comprising the following steps:

[0017] S1. The raw materials for the surface layer, the middle layer and the inner layer are mixed in proportion and then put into a mixer and mixed evenly, and then respectively fed into an extruder to melt;

[0018] S2. According to the order of the surface layer, the middle layer and the inner layer, the co-extrusion casting is performed by an extruder and cooled to shape;

[0019] S3. The shaped film is subjected to corona treatment to obtain the desired film-like polyolefin material.

[0020] The third object of the present invention is to provide a polyolefin material for coating with soft surface performance as described above for use in product coating.

[0021] The beneficial effects of the present invention are:

[0022] The present invention provides a polyolefin material for film coating with soft surface performance. The material is a three-layer composite film structure. Through special functional formula design and multi-layer co-extrusion casting processing technology, good ductility is obtained, and the polyolefin film is particularly suitable for coating irregular objects. In addition, the polyolefin film has low production cost, low equipment investment, simple process, can well meet market demand, and has high application value.

[0023] In this polyolefin material, the surface layer is a modified heat-resistant layer, which is composed of high-crystalline polypropylene homopolymer resin HD915CF produced by Borealis and Asahi Denka rigidity-enhancing nucleating agent NA-27. Borealis HD915CF is a high-crystalline polypropylene homopolymer resin produced based on North Star polymerization technology and using the unique North Star nucleating technology (BNT), which can provide better rigidity and toughness for film structures. Asahi Denka rigidity-enhancing nucleating agent NA-27 is an organic phosphite-based mixture that can increase the crystallization temperature (Tc) of polypropylene and improve the physical properties of polypropylene such as heat deformation temperature (HDT) and flexural modulus, thereby achieving an excellent balance of physical properties (especially stiffness / impact).

[0024] The middle layer is the support layer, which is composed of homopolymer polypropylene resin FC801 produced by Shanghai Petrochemical and high crystalline polypropylene homopolymer resin HD915CF produced by Borealis. Among them, FC801 homopolymer polypropylene (PP-H) is polymerized from a single propylene monomer, and its molecular chain has high regularity, high crystallinity, good strength and corrosion resistance. HD915CF is a high crystalline polypropylene homopolymer resin produced based on North Star polymerization technology and using the unique North Star nucleation technology (BNT), which can further improve the rigidity and toughness of the film structure.

[0025] The inner layer is a heat-bonded sealing layer, which is made of FL7642 polypropylene copolymer resin produced by Singapore TPC and TAFMER, a special n-butene-based olefin copolymer produced by Mitsui of Japan. TM BL2491M, open masterbatch AB PP 10S provided by Polylide, and PP smooth masterbatch SLPP-7 provided by Beijing Yalun. Among them, FL7642 has good fluidity at melting temperature, good molding performance, excellent processing performance and good thermal stability (decomposition temperature is 310℃). TM BL2491M is a special n-butene-based olefin copolymer used to reduce the sealing temperature of polypropylene film. It has the characteristics of low melting point and good compatibility with polypropylene.

[0026] Experiments show that the polyolefin film prepared by the present invention has good ductility, a maximum tensile strength of 80.1 MPa in the MD direction, an elongation at break of more than 726% in the TD direction, and a relatively balanced stiffness and impact resistance, wherein the puncture strength is more than 12.7 N. The polyolefin film used for coating can provide good protection for contents and coated articles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of the polyolefin material provided by the present invention.

[0028] The meanings of the symbols in the figure are as follows:

[0029] 10-modified heat-resistant layer 20-support layer 30-heat-bonding sealing layer DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described below in conjunction with the accompanying drawings and embodiments for easy understanding by those skilled in the art.

[0031] like Figure 1 As shown, a polyolefin material for laminating with soft surface performance is a three-layer composite film, which includes, from the outside to the inside, a surface layer, i.e. a modified heat-resistant layer 10, an intermediate layer, i.e. a support layer 20, and an inner layer, i.e. a heat-bonding sealing layer 30. The total thickness of the three-layer composite film is 70-90 μm, preferably 80 μm.

[0032] Among them, the modified heat-resistant layer 10 has a thickness of 20 to 24 μm, and is composed of 99.5wt% polypropylene homopolymer resin HD915CF and 0.5wt% polypropylene stiffener nucleating agent NA-27; the middle layer is a support layer 20, with a thickness of 38 to 42 μm, and is composed of 60wt% homopolymer polypropylene resin FC801 and 40wt% polypropylene homopolymer resin HD915CF; the inner layer is a heat-bonding sealing layer 30, with a thickness of 16 to 20 μm, and is composed of (42 to 48)wt% polypropylene copolymer resin FL7642, (47 to 53)wt% n-butene olefin copolymer BL2491M, 3wt% open masterbatch ABPP 10S and 2wt% smooth masterbatch SLPP-7.

[0033] The polyolefin material of the present invention is produced by a non-stretching, non-directional flat extrusion process using a three-layer cast film device through which the melt extruded by multiple twin-screw extruders is quenched by a cast film device, and the steps are as follows:

[0034] S1. The raw materials for the surface layer, the middle layer and the inner layer are mixed in proportion and then put into a mixer and mixed evenly, and then respectively fed into an extruder to melt;

[0035] S2. According to the order of the surface layer, the middle layer and the inner layer, the co-extrusion casting is performed by an extruder and cooled to shape;

[0036] S3. The shaped film is subjected to corona treatment to obtain the desired film-like polyolefin material.

[0037] The polyolefin three-layer film was prepared according to the above method using a three-layer casting equipment model MIDEX2500 produced by Reifenhäuser of Germany.

[0038] The surface layer, support layer and inner layer raw materials are respectively added into the three barrels of the co-extrusion casting equipment, and the raw materials in the three barrels are co-extruded and then enter the casting station, and the temperatures of the three barrels of the extruder are set to 220°C for the first stage, 255°C for the second stage, 250°C for the third stage, and the die head temperature is 240°C; in the casting process, the roller surface temperature of the casting roller is set to 15°C, and the surface layer is subjected to corona treatment after the casting is finalized, and a film material is obtained after the corona treatment.

[0039] Referring to Table 1 below, the thickness ratio is adjusted to obtain the following Examples 1 to 3:

[0040] Table 1 Raw material formula of each layer prepared in Examples 1-3

[0041]

[0042]

[0043] Comparative Example 1 was prepared using a conventional three-layer cast polypropylene film production formula in the prior art. The formula information of Comparative Example 1 is shown in Table 2 below, wherein FC801MX is a homopolymer polypropylene resin from Shanghai Petrochemical, and SFC750R is a copolymer polypropylene resin from Hunan Petrochemical.

[0044] Table 2 Comparative Example 1 Raw Material Formula

[0045]

[0046] At the same time, the finished film-coated product produced by common BOPP (biaxially oriented polypropylene film) by coating hot melt adhesive and cooling and shaping under specific production process conditions is comparative example 2, and the performance tests are carried out respectively with embodiments 1-3 and comparative example 1. The results are shown in Table 3.

[0047] Table 3 Performance comparison of Examples 1-3 and Comparative Examples 1-2

[0048]

[0049]

[0050] It can be seen that the polyolefin film prepared by the present invention has good ductility, and its tensile strength in the MD direction is up to 80.1MPa, which is better than the comparative example, and the elongation at break in the TD direction is greater than 726%, which can be applied to the coating needs of irregular goods. In addition, the stiffness and impact resistance are relatively balanced, and the puncture strength is greater than 12.7N, which is much higher than the comparative example. The film prepared by the present invention can play a good protective role on the contents and the coated articles when used for coating.

[0051] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyolefin material for coating with soft surface performance, characterized in that: The polyolefin material is in the form of a film and comprises three layers from the outside to the inside: The surface layer is a modified heat-resistant layer (10) with a thickness of 20 to 24 μm, and is composed of 99.5 wt% polypropylene homopolymer resin and 0.5 wt% polypropylene modification auxiliary agent; The middle layer is a support layer (20), with a thickness of 38 to 42 μm, and is composed of 60 wt % homopolymer polypropylene resin and 40 wt % homopolymer polypropylene resin; The inner layer is a heat-bonding sealing layer (30) with a thickness of 16 to 20 μm and is composed of (42 to 48) wt% polypropylene copolymer resin, (47 to 53) wt% n-butene olefin copolymer and 5 wt% additives.

2. A polyolefin material for coating with soft surface performance as claimed in claim 1, characterized in that: The polypropylene modification aid is a rigidity-enhancing nucleating agent, and the additives include an open masterbatch and a smooth masterbatch in a mass ratio of 3:

2.

3. The polyolefin material for coating with soft surface performance as claimed in claim 2, characterized in that: The polypropylene homopolymer resin is brand HD915CF, the homopolymer polypropylene resin is brand FC801, the polypropylene copolymer resin is brand FL7642, the n-butene olefin copolymer is brand BL2491M, the rigidity enhancing nucleating agent is brand NA-27, the open masterbatch is brand ABPP 10S, and the slip masterbatch is brand SLPP-7.

4. The polyolefin material for coating with soft surface performance as claimed in claim 1, characterized in that: The total thickness of the polyolefin material is 70-90 μm.

5. The polyolefin material for coating with soft surface performance as claimed in claim 4, characterized in that: The thickness of the polyolefin material is 80 μm, the thickness of the surface layer is 22 μm, the thickness of the middle layer is 40 μm, and the thickness of the inner layer is 12 μm.

6. A method for preparing a polyolefin material for coating with soft surface properties as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The raw materials for the surface layer, the middle layer and the inner layer are mixed in proportion and then put into a mixer and mixed evenly, and then respectively fed into an extruder to melt; S2. Co-extrusion casting is performed by an extruder in the order of the surface layer, the middle layer and the inner layer, and the cooling and shaping is performed; S3. The shaped film is subjected to corona treatment to obtain the desired film-like polyolefin material.

7. Use of the polyolefin material for laminating with soft surface properties as claimed in any one of claims 1 to 5 in product laminating.

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