High modulus synthetic paper substrate, process for its production and use

Abstract

The application relates to the technical field of film processing, and discloses a high-modulus synthetic paper substrate and a production process and application thereof. The synthetic paper substrate is a 4-8-layer co-extrusion structure; the synthetic paper substrate comprises an upper surface layer, a secondary upper surface layer, a core layer, a secondary lower surface layer and a lower surface layer which are stacked in sequence from top to bottom; and the secondary upper surface layer and the secondary lower surface layer are modulus-enhancing layers. (1) The modulus of the synthetic paper substrate is enhanced by adding PMMA powder and glass fibers to the secondary upper surface layer and the secondary lower surface layer; (2) In the core layer, calcium sulfate, zinc carbonate and aluminum hydroxide are selected as inorganic foaming materials, and the foaming performance of the three materials after mixing is better than that of calcium carbonate used alone. Under the same density, the foaming cavity structure of the synthetic paper substrate is more fine and uniform, the mechanical property is better than that of an existing product, and the modulus is increased by 50%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of film processing, in particular to a high modulus synthetic paper substrate and its production process and application. BACKGROUND

[0002] The synthetic paper products on the market at present widely use inorganic fillers such as calcium carbonate (CaCO3) for physical foaming, so that the synthetic paper presents white luster. However, physical foaming will affect the mechanical properties of the synthetic paper, such as the decrease of tensile strength and Young's modulus, which will bring great influence on the subsequent processing process. After physical foaming, the density of the film decreases, and with the increase of the amount of calcium carbonate, the density decreases in direct proportion. Due to the difference in application fields, the density of the synthetic paper on the market is generally 0.6-0.8 g / cm3. The Young's modulus is usually low: in the longitudinal direction, it is in the range of 1000-1500 MPa; in the transverse direction, it is in the range of 1800-2000 MPa. In order to increase the stiffness, the thickness of the film can only be increased.

[0003] At present, in order to solve this problem, the film manufacturers usually increase the thickness of the synthetic paper, for example, the thickness of almost all synthetic paper substrates on the market exceeds 80 μm, and most of them are increased to 120 μm. In this way, the stiffness of the synthetic paper is increased, and the product quality problems caused by insufficient stiffness of the synthetic paper substrate in the production and processing process of the downstream manufacturers are avoided. However, although the stiffness of the existing synthetic paper is improved, the Young's modulus of the synthetic paper is still low, and the thickness of the synthetic paper is too high, which limits the application range of the synthetic paper.

[0004] Therefore, it is necessary to develop a high modulus synthetic paper substrate and its production process and application, which can increase the Young's modulus of the synthetic paper and at the same time reduce the thickness of the synthetic paper substrate. SUMMARY

[0005] The present application aims at at least solving one of the technical problems existing in the prior art. To this end, the present application proposes a high modulus synthetic paper substrate and its production process and application, which can increase the Young's modulus of the synthetic paper and at the same time reduce the thickness of the synthetic paper substrate.

[0006] The first aspect of the present application provides a high modulus synthetic paper substrate.

[0007] Specifically, the synthetic paper substrate is a 4-8 layer co-extrusion structure; the synthetic paper substrate comprises an upper surface layer, a lower surface layer, a core layer, a lower surface layer, and a lower surface layer stacked from top to bottom; the lower surface layer and the lower surface layer are modulus enhancement layers.

[0008] Preferably, the core layer and the lower surface layer further comprise a functional co-extrusion layer.

[0009] Further preferably, the thickness of the functional co-extrusion layer is 10-200 μm.

[0010] The functional co-extrusion layer can be added with different film additives according to market demand, and the functions thereof include flame retardation, aging resistance and degradability.

[0011] Preferably, the raw materials of the upper and lower surface layers comprise, by weight fraction, 95-98 parts of polyolefin, 2-5 parts of silicon dioxide.

[0012] The upper surface layer is coated with an ink absorption layer, and the lower surface layer is coated with glue, thereby providing good surface properties for the glue coating of downstream manufacturers.

[0013] Preferably, the raw materials of the upper and lower surface layers comprise, by weight fraction, 95-98 parts of polyolefin, 2-5 parts of silicon dioxide.

[0014] Further preferably, the raw materials of the upper and lower surface layers comprise, by weight fraction, 95-98 parts of polyolefin, 2-5 parts of silicon dioxide.

[0015] Preferably, the formula and manufacturing process of the calcium-zinc stabilizer are as follows: calcium stearate and zinc stearate are mixed at a weight ratio of 1:1, and then the mixture 5% (i.e. 2.5% of calcium stearate and 2.5% of zinc stearate), PMMA powder 30%, glass fiber powder 30% and polypropylene 35% are mixed at a weight ratio, and then the mixture is melted at 230℃, extruded and granulated by a double screw machine, and cooled to obtain the calcium-zinc stabilizer.

[0016] The upper and lower surface layers can enhance the modulus of the synthetic paper substrate.

[0017] Preferably, the particle size of the PMMA powder is 500-2000 mesh.

[0018] Preferably, the raw materials of the core layer comprise, by weight fraction, 50-70 parts of polypropylene, 8-18 parts of calcium sulfate, 8-18 parts of zinc carbonate, 8-18 parts of aluminum hydroxide and 1-5 parts of dihydroxypropyl octadecanoate.

[0019] The core layer is the main extrusion layer of the synthetic paper substrate, and the material used therein is white after foaming, and can partially replace paper.

[0020] Preferably, the thickness of the upper and lower surface layers is 2-10 μm, the thickness of the upper and lower surface layers is 3-20 μm, and the thickness of the core layer is 10-200 μm.

[0021] The second aspect of the application provides a production process of a synthetic paper substrate.

[0022] Specifically, the method comprises the following steps:

[0023] (1) by controlling the extrusion temperature of each co-extrusion layer of the synthetic paper substrate; the extrusion temperature of the upper surface layer is 220-250 DEG C; the extrusion temperature of the lower surface layer is 220-250 DEG C; the extrusion temperature of the core layer is 190-260 DEG C; the extrusion temperature of the lower surface layer is 230-250 DEG C; the extrusion temperature of the lower surface layer is 220-250 DEG C;

[0024] (2) longitudinal stretching and transverse stretching are carried out after casting;

[0025] (3) the upper surface layer and the lower surface layer are subjected to corona treatment after stretching;

[0026] (4) the finished product is wound and cut, and the synthetic paper substrate is prepared.

[0027] Specifically, the extrusion temperature of the functional co-extrusion layer is 220-230 DEG C.

[0028] Preferably, in step (2), the longitudinal stretching ratio is 4-6 times; and the transverse stretching ratio is 6-10 times.

[0029] Preferably, in step (4), the finished product is wound and cut after aging for 24-72 h.

[0030] The third aspect of the present application provides a synthetic paper substrate for use in label printing substrates, adhesive label substrates, daily-use label substrates, inkjet printing supplies, label materials, outdoor advertisements and posters.

[0031] Specifically, the daily-use label substrates include electronic product label substrates, food label substrates and beverage label substrates.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] (1) the present application adds PMMA powder and glass fibers to the lower surface layer and the lower surface layer, thereby enhancing the modulus of the synthetic paper substrate;

[0034] (2) the inorganic filler of the core layer of the present application is selected from calcium sulfate, zinc carbonate and aluminum hydroxide as inorganic foaming materials, and the foaming performance of the three materials after mixing is better than that of calcium carbonate alone. Under the same density, the foaming hole structure of the synthetic paper substrate of the present application is more fine and uniform, and the mechanical properties are also better than those of the existing products, and the modulus is increased by 50%. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 FIG. 1 is a structural schematic diagram of the synthetic paper substrate of the present application. DETAILED DESCRIPTION

[0036] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0037] The raw materials, reagents or devices used in the following examples, if not specifically mentioned, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0038] Example 1

[0039] A synthetic paper substrate and its production process.

[0040] The raw materials of each layer are as follows in terms of weight fraction:

[0041] Upper surface layer: 98 parts of polypropylene (PP) and 2 parts of silicon dioxide (SiO2);

[0042] Sub-upper surface layer: 88 parts of polypropylene, 5 parts of PMMA powder, 5 parts of glass fiber powder, and 2 parts of calcium-zinc stabilizer particles;

[0043] Core layer: 60 parts of polypropylene, 15 parts of calcium sulfate, 10 parts of zinc carbonate, 13 parts of aluminum hydroxide, and 2 parts of dihydroxypropyl octadecyl stearate;

[0044] Sub-lower surface layer: 88 parts of polypropylene, 5 parts of PMMA powder, 5 parts of glass fiber powder, and 2 parts of calcium-zinc stabilizer particles;

[0045] Lower surface layer: 98 parts of polypropylene and 2 parts of silicon dioxide (SiO2);

[0046] The thickness of the upper surface layer is 5 μm, the thickness of the sub-upper surface layer is 10 μm, the thickness of the core layer is 40 μm, the thickness of the sub-lower surface layer is 10 μm, and the thickness of the lower surface layer is 5 μm.

[0047] Specific production process:

[0048] The extrusion temperature of the upper surface layer is 230℃;

[0049] The extrusion temperature of the sub-upper surface layer is 235℃;

[0050] The extrusion temperature of the core layer is 240℃;

[0051] The extrusion temperature of the sub-lower surface layer is 235℃;

[0052] The extrusion temperature of the lower surface layer is 230℃;

[0053] The transverse stretching ratio is 8 times;

[0054] The transverse stretching temperature is 160℃;

[0055] The longitudinal stretching ratio is 5 times;

[0056] Longitudinal stretching temperature 130℃.

[0057] The effect of the synthetic paper substrate of Example 1 finished product:

[0058] The thickness of the synthetic paper substrate: 70μm;

[0059] Density: 0.7g / cm3;

[0060] Tensile strength test: 110MPa in the longitudinal direction (MD); 190MPa in the transverse direction (CD);

[0061] Test method: Refer to GB / T 1040.3-2006 Determination of tensile properties of plastics Part 3: test conditions for films and sheets;

[0062] Young's modulus test: 2200MPa in the longitudinal direction (MD); 3500MPa in the transverse direction (CD).

[0063] Test method: Refer to GB / T 1040.3-2006 Determination of tensile properties of plastics Part 3: test conditions for films and sheets.

[0064] Example 2

[0065] A synthetic paper substrate and its production process.

[0066] The raw materials of each layer are as follows by weight fraction:

[0067] Upper surface layer: 98 parts of PP, 2 parts of SiO2;

[0068] Sub-upper surface layer: 88 parts of PP, 5 parts of PMMA, 5 parts of glass fiber powder, 2 parts of calcium zinc stabilizer;

[0069] Core layer: 70 parts of PP, 10 parts of calcium sulfate, 10 parts of zinc carbonate, 8 parts of aluminum hydroxide, 2 parts of dihydroxypropyl octadecanoate;

[0070] Sub-lower surface layer: 88 parts of PP, 5 parts of PMMA, 5 parts of glass fiber powder, 2 parts of calcium zinc stabilizer;

[0071] Lower surface layer: 98 parts of PP, 2 parts of SiO2;

[0072] The thickness of the upper surface layer is 5μm, the thickness of the sub-upper surface layer is 10μm, the thickness of the core layer is 40μm, the thickness of the sub-lower surface layer is 10μm, and the thickness of the lower surface layer is 5μm.

[0073] Specific production process:

[0074] The extrusion temperature of the upper surface layer is 230℃;

[0075] The extrusion temperature of the sub-upper surface layer is 235℃;

[0076] Core layer extrusion temperature: 240℃;

[0077] Sub-under layer extrusion temperature: 235℃;

[0078] Under layer extrusion temperature: 230℃;

[0079] Transverse stretching ratio: 8 times;

[0080] Transverse stretching temperature 160℃;

[0081] Longitudinal stretching ratio: 5 times;

[0082] Longitudinal stretching temperature 140℃.

[0083] Example 2 synthetic paper substrate finished product effect:

[0084] Synthetic paper substrate thickness: 70μm;

[0085] Density: 0.8g / cm3;

[0086] Tensile strength test: 130MPa in the longitudinal direction (MD) and 210MPa in the transverse direction (CD);

[0087] Young's modulus test: 2500MPa in the longitudinal direction (MD) and 4000MPa in the transverse direction (CD).

[0088] The above test method: refer to GB / T 1040.3-2006 Determination of tensile properties of plastics Part 3: test conditions for films and sheets.

[0089] Example 3

[0090] A synthetic paper substrate and its production process.

[0091] The raw materials of each layer are as follows in terms of weight ratio:

[0092] Upper layer: 98 parts of PP, 2 parts of SiO2;

[0093] Sub-upper layer: 80 parts of PP, 9 parts of PMMA, 9 parts of glass fiber powder, and 2 parts of calcium zinc stabilizer;

[0094] Core layer: 50 parts of polypropylene, 15 parts of calcium sulfate, 15 parts of zinc carbonate, 15 parts of aluminum hydroxide, and 5 parts of dihydroxypropyl octadecyl stearate;

[0095] Sub-under layer: 80 parts of PP, 9 parts of PMMA, 9 parts of glass fiber powder, and 2 parts of calcium zinc stabilizer;

[0096] Under layer: 98 parts of PP, 2 parts of SiO2;

[0097] The upper surface layer has a thickness of 5 μm, the sub-upper surface layer has a thickness of 10 μm, the core layer has a thickness of 40 μm, the sub-lower surface layer has a thickness of 10 μm, and the lower surface layer has a thickness of 5 μm.

[0098] The specific production process is as follows:

[0099] The extrusion temperature of the upper surface layer is 230°C.

[0100] The extrusion temperature of the sub-upper surface layer is 235°C.

[0101] The extrusion temperature of the core layer is 240°C.

[0102] The extrusion temperature of the sub-lower surface layer is 235°C.

[0103] The extrusion temperature of the lower surface layer is 230°C.

[0104] The transverse stretching ratio is 8 times.

[0105] The transverse stretching temperature is 150°C.

[0106] The longitudinal stretching ratio is 5 times.

[0107] The longitudinal stretching temperature is 130°C.

[0108] The finished effect of the synthetic paper substrate of Example 3 is as follows:

[0109] The thickness of the synthetic paper substrate is 70 μm.

[0110] The density is 0.6 g / cm3.

[0111] The tensile strength test: the longitudinal (MD) is 88 MPa; and the transverse (CD) is 130 MPa.

[0112] The Young's modulus test: the longitudinal (MD) is 2000 MPa; and the transverse (CD) is 3000 MPa.

[0113] The above test method refers to GB / T 1040.3-2006 Determination of tensile properties of plastics Part 3: test conditions for films and sheets.

[0114] From Example 1 to Example 3, it can be seen that the use of organic powder PMMA to promote crystallization, inorganic powder such as calcium sulfate powder and zinc carbonate powder for foaming, whether the density of the film is controlled at 0.6 g / cm3or 0.8 g / cm3, the modulus exceeds the original synthetic paper modulus by more than 50%. With the increase and decrease of the amount of foaming powder, the density of the synthetic paper film also decreases and increases. From the same density application requirement, the thickness of the synthetic paper film can be reduced by more than 30%, greatly reducing the cost and reducing resource consumption.

[0115] The preferred embodiments of the present application have been described above in detail. It should be understood that modifications and variations to the present application can be affected by those skilled in the art without departing from the scope of the application. Accordingly, it is intended that all possible modifications and alterations be included within the scope of the present application as defined by the following claims.

Claims

1. A high modulus synthetic paper substrate, characterized by, The synthetic paper substrate is a 4-8 layer co-extrusion structure; the synthetic paper substrate comprises an upper surface layer, a lower surface layer, a core layer, a lower surface layer, and a lower surface layer stacked from top to bottom; the raw materials of the upper surface layer and the lower surface layer comprise, by weight fraction: 95-98 parts of polypropylene, 2-5 parts of silicon dioxide, and the thickness is 2-10 μm; the raw materials of the lower surface layer and the lower surface layer comprise, by weight fraction: 80-95 parts of polypropylene, 1-15 parts of polymethyl methacrylate powder, 2-15 parts of glass fiber, 1-2 parts of calcium zinc stabilizer, and the thickness is 3-20 μm; the raw materials of the core layer comprise, by weight fraction: 50-70 parts of polypropylene, 8-18 parts of calcium sulfate, 8-18 parts of zinc carbonate, 8-18 parts of aluminum hydroxide, 1-5 parts of dihydroxypropyl octadecanoate, and the thickness is 10-200 μm.

2. The synthetic paper substrate of claim 1, wherein, The core layer and the lower surface layer further comprise a functional co-extrusion layer.

3. The synthetic paper substrate of claim 1, wherein, The particle size of the polymethyl methacrylate powder is 500-2000 mesh.

4. The production process of synthetic paper substrate according to any one of claims 1 to 3, characterized in that, The steps comprise: (1) By controlling the extrusion temperature of each co-extrusion layer of the synthetic paper substrate: the extrusion temperature of the upper surface layer is 220-250℃; the extrusion temperature of the lower surface layer is 230-250℃; the extrusion temperature of the core layer is 190-260℃; the extrusion temperature of the lower surface layer is 230-250℃; the extrusion temperature of the lower surface layer is 220-250℃; (2) After casting, longitudinal stretching and transverse stretching are carried out; (3) After stretching, the upper surface layer and the lower surface layer are subjected to corona treatment; (4) The finished product is wound and cut to obtain the synthetic paper substrate.

5. The production process according to claim 4, characterized in that, In step (2), the longitudinal stretching ratio is 4-6 times; the transverse stretching ratio is 6-10 times.

6. Use of the synthetic paper substrate of any one of claims 1-3 or the production process of any one of claims 4-5 in the preparation of inkjet printing supplies, label materials, and posters.

7. Use according to claim 6, characterized in that, The label material comprises a label printing substrate, an adhesive label substrate, or a daily use label substrate.

8. Use according to claim 6, characterized in that, The poster comprises an outdoor advertisement.

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