High toughness gusseted bag and method of making same

Abstract

The application relates to the technical field of plastic bags, and discloses a high-toughness square-bottom bag and a preparation method thereof, wherein the high-toughness square-bottom bag comprises an inner layer, a middle layer and an outer layer from inside to outside; the inner layer comprises the following components in parts by weight: 100 parts of polyethylene, 20-30 parts of ethylene-propylene copolymer and 10-15 parts of polylactic acid; the middle layer comprises the following components in parts by weight: 100 parts of ethylene-propylene copolymer, 25-35 parts of ethylene-vinyl alcohol copolymer and 10-14 parts of silicon dioxide; and the outer layer comprises the following components in parts by weight: 100 parts of polyethylene and 6-8 parts of ethylene-acrylic acid copolymer. Through the technical scheme, the problems of poor toughness and low strength of the square-bottom bag in the related art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic bags, in particular to a high-toughness square-bottom bag and a preparation method thereof. BACKGROUND

[0002] Plastic bags are made of plastic as the main raw material through a blowing film process. Due to its low cost, large capacity and convenience, it is widely used in various fields. Square-bottom bags are one of the plastic bags, and the bottom of the plastic bag is designed as a square shape, which can be customized according to the size of the packaged product. The wide application of square-bottom bags in the packaging field of food, medicine, industry, agriculture and daily necessities has good sealing and barrier properties. However, the existing square-bottom bags still have the problems of insufficient toughness and low strength, which limits the further application of square-bottom bags. Therefore, a square-bottom bag with high toughness and high strength is needed. SUMMARY

[0003] The present application provides a high-toughness square-bottom bag and a preparation method thereof, which solves the problems of poor toughness and low strength of the square-bottom bag in the related art.

[0004] The technical scheme of the present application is as follows:

[0005] The present application provides a high-toughness square-bottom bag, which comprises an inner layer, an intermediate layer and an outer layer from inside to outside.

[0006] The inner layer comprises the following components by weight: polyethylene 100 parts, ethylene-propylene copolymer 20-30 parts, polylactic acid 10-15 parts, and antioxidant 1-2 parts.

[0007] The intermediate layer comprises the following components by weight: ethylene-propylene copolymer 100 parts, ethylene-vinyl alcohol copolymer 25-35 parts, and silicon dioxide 10-14 parts.

[0008] The outer layer comprises the following components by weight: polyethylene 100 parts, ethylene-acrylic acid copolymer 6-8 parts, and antioxidant 1-2 parts.

[0009] As a further technical scheme, the melt index of the polylactic acid at 210℃ / 2.16kg is 7-23g / 10min.

[0010] In the present application, the melt index of the polylactic acid at 210℃ / 2.16kg is limited to 7-23g / 10min, and then cooperates with ethylene-vinyl alcohol copolymer and ethylene-acrylic acid copolymer in different layers, which further improves the toughness and strength of the square-bottom bag.

[0011] As a further technical solution, the thickness of the inner layer is 0.1-0.15 mm; the thickness of the intermediate layer is 0.2-0.3 mm; and the thickness of the outer layer is 0.05-0.2 mm.

[0012] As a further technical solution, the molar content of ethylene in the ethylene-vinyl alcohol copolymer is 27%-38%.

[0013] As a further technical solution, the molar content of acrylic acid in the ethylene-acrylic acid copolymer is 7%-10%.

[0014] In the present application, by limiting the molar content of acrylic acid in the ethylene-acrylic acid copolymer to 7%-10%, and cooperating with the ethylene-vinyl alcohol copolymer and polyacrylic acid in different layers, the toughness and strength of the square bottom bag are further improved.

[0015] As a further technical solution, the silicon dioxide is PBAT modified silicon dioxide.

[0016] In the present application, PBAT is used to modify the silicon dioxide, improve the compatibility of the silicon dioxide in the polymer matrix, and improve the interlayer bonding force, thereby further improving the toughness and strength of the square bottom bag.

[0017] As a further technical solution, the preparation method of the PBAT modified silicon dioxide comprises the following steps: dissolving PBAT and mixing with silicon dioxide, removing the solvent, and obtaining PBAT modified silicon dioxide.

[0018] As a further technical solution, the mass ratio of the PBAT to the silicon dioxide is 1:10-14.

[0019] As a further technical solution, the model of the PBAT is BFX3091 and / or C1200.

[0020] As a further technical solution, when the model of the PBAT is BFX3091 and C1200, the mass ratio of PBAT-BFX3091 to PBAT-C1200 is 2:3-3:2.

[0021] In the present application, when the model of the PBAT is BFX3091 and C1200, and the mass ratio of PBAT-BFX3091 to PBAT-C1200 is 2:3-3:2, the silicon dioxide is modified, thereby further improving the toughness and strength of the square bottom bag.

[0022] The present application also proposes a preparation method of the high-toughness square bottom bag, comprising the following steps:

[0023] The components of the inner layer, the middle layer and the outer layer are mixed respectively, and then three-layer co-extrusion blown film molding is performed to obtain the high-toughness square bottom bag.

[0024] The working principle and beneficial effects of the present application are as follows:

[0025] In the present application, the polylactic acid, ethylene-vinyl alcohol copolymer and ethylene-acrylic acid copolymer in different layers are used to make the inner layer, the middle layer and the outer layer cooperate with each other, improve the combination and toughness between the three layers, and finally significantly improve the toughness and strength of the square bottom bag. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] In the following examples and comparative examples, the type of polyethylene is 2420H; the type of ethylene-propylene copolymer is Taizhong Yongjia 3080.

[0028] Example 1

[0029] The high-toughness square bottom bag comprises an inner layer, a middle layer and an outer layer from inside to outside; the thickness of the inner layer is 0.1 mm; the thickness of the middle layer is 0.2 mm; and the thickness of the outer layer is 0.2 mm.

[0030] The inner layer comprises the following components in parts by weight: 100 parts of polyethylene, 20 parts of ethylene-propylene copolymer, 10 parts of polylactic acid and 1 part of antioxidant 1076.

[0031] The middle layer comprises the following components in parts by weight: 100 parts of ethylene-propylene copolymer, 25 parts of ethylene-vinyl alcohol copolymer and 10 parts of silicon dioxide.

[0032] The outer layer comprises the following components in parts by weight: 100 parts of polyethylene, 6 parts of ethylene-acrylic acid copolymer and 2 parts of antioxidant 1076.

[0033] The melt index of the polylactic acid at 210℃ / 2.16kg is 6g / 10min (type LX175); the molar content of ethylene in the ethylene-vinyl alcohol copolymer is 27% (item number 55207345, from Shanghai Zhenzhun Biological Technology Co., Ltd.); and the molar content of acrylic acid in the ethylene-acrylic acid copolymer is 6.5% (type 3003).

[0034] The preparation method of the high-toughness square bottom bag comprises the following steps:

[0035] The components of the inner layer, the middle layer and the outer layer are mixed respectively, and then three-layer co-extrusion blown film molding is performed to obtain the high-toughness square bottom bag.

[0036] Example 2

[0037] The high-toughness square bottom bag comprises, from inside to outside, an inner layer, a middle layer and an outer layer; the thickness of the inner layer is 0.15 mm; the thickness of the middle layer is 0.3 mm; and the thickness of the outer layer is 0.05 mm.

[0038] The inner layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-propylene copolymer 30 parts, polylactic acid 15 parts, antioxidant 1076 2 parts.

[0039] The middle layer comprises the following components in parts by weight: ethylene-propylene copolymer 100 parts, ethylene-vinyl alcohol copolymer 35 parts, silicon dioxide 14 parts.

[0040] The outer layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-acrylic acid copolymer 8 parts, antioxidant 1076 1 part.

[0041] The polylactic acid has a melt index of 6 g / 10 min (model LX175) at 210℃ / 2.16 kg; the ethylene-vinyl alcohol copolymer has a molar content of ethylene of 38% (item number 55207347, from Shanghai Zhenzhun Biological Technology Co., Ltd.); and the ethylene-acrylic acid copolymer has a molar content of acrylic acid of 6.5% (model 3003).

[0042] The method for preparing the high-toughness square bottom bag comprises the following steps:

[0043] The components of the inner layer, the middle layer and the outer layer are mixed respectively, and then three-layer co-extrusion blown film molding is performed to obtain the high-toughness square bottom bag.

[0044] Example 3

[0045] The high-toughness square bottom bag comprises, from inside to outside, an inner layer, a middle layer and an outer layer; the thickness of the inner layer is 0.1 mm; the thickness of the middle layer is 0.2 mm; and the thickness of the outer layer is 0.2 mm.

[0046] The inner layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-propylene copolymer 25 parts, polylactic acid 12 parts, antioxidant 1076 2 parts.

[0047] The middle layer comprises the following components in parts by weight: ethylene-propylene copolymer 100 parts, ethylene-vinyl alcohol copolymer 28 parts, silicon dioxide 12 parts.

[0048] The outer layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-acrylic acid copolymer 8 parts, antioxidant 1076 1 part.

[0049] wherein the poly-lactic acid has a melt index of 6 g / 10 min at 210°C / 2.16 kg (model LX175); the ethylene-vinyl alcohol copolymer has a molar content of ethylene of 32% (item number 55207346, from Shanghai Zhenzhun Biological Technology Co., Ltd.); the ethylene-acrylic acid copolymer has a molar content of acrylic acid of 6.5% (model 3003);

[0050] A method for preparing a high-toughness gusset bag, comprising the following steps:

[0051] After mixing the components of the inner layer, the middle layer, and the outer layer respectively, a high-toughness gusset bag is obtained by three-layer co-extrusion and film blowing.

[0052] Example 4

[0053] The difference between this example and Example 3 is only that the poly-lactic acid has a melt index of 70 g / 10 min at 210°C / 2.16 kg (model L105).

[0054] Example 5

[0055] The difference between this example and Example 3 is only that the poly-lactic acid has a melt index of 7 g / 10 min at 210°C / 2.16 kg (model LX575).

[0056] Example 6

[0057] The difference between this example and Example 3 is only that the poly-lactic acid has a melt index of 23 g / 10 min at 210°C / 2.16 kg (model LX530).

[0058] Example 7

[0059] The difference between this example and Example 6 is only that the ethylene-acrylic acid copolymer has a molar content of acrylic acid of 25% (model 5980).

[0060] Example 8

[0061] The difference between this example and Example 6 is only that the ethylene-acrylic acid copolymer has a molar content of acrylic acid of 7% (model 5050).

[0062] Example 9

[0063] The difference between this example and Example 6 is only that the ethylene-acrylic acid copolymer has a molar content of acrylic acid of 10% (model 373).

[0064] Example 10

[0065] The difference between this example and Example 9 is only that the silicon dioxide is PBAT modified silicon dioxide.

[0066] The preparation method of the PBAT modified silicon dioxide comprises the following steps: 1g of PBAT is dissolved in 40g of chloroform, 12g of silicon dioxide is added for mixing, and the chloroform is removed to obtain the PBAT modified silicon dioxide; wherein the model of the PBAT is BFX3091.

[0067] Example 11

[0068] The difference between this example and example 10 is only that the model of the PBAT is C1200.

[0069] Example 12

[0070] The difference between this example and example 10 is only that the PBAT is a mixture of PBAT-BFX3091 and PBAT-C1200 with a mass ratio of 1:4.

[0071] Example 13

[0072] The difference between this example and example 10 is only that the PBAT is a mixture of PBAT-BFX3091 and PBAT-C1200 with a mass ratio of 4:1.

[0073] Example 14

[0074] The difference between this example and example 10 is only that the PBAT is a mixture of PBAT-BFX3091 and PBAT-C1200 with a mass ratio of 2:3.

[0075] Example 15

[0076] The difference between this example and example 10 is only that the PBAT is a mixture of PBAT-BFX3091 and PBAT-C1200 with a mass ratio of 3:2.

[0077] Comparative Example 1

[0078] The difference between this comparative example and example 3 is only that no polylactic acid is added in the component of the inner layer.

[0079] Comparative Example 2

[0080] The difference between this comparative example and example 3 is only that no ethylene-vinyl alcohol copolymer is added in the component of the middle layer.

[0081] Comparative Example 3

[0082] The difference between this comparative example and example 3 is only that no ethylene-acrylic acid copolymer is added in the component of the outer layer.

[0083] The square bottom bags prepared from Examples 1-15 and Comparative Examples 1-3 were tested for tensile strength and elongation at break according to standard GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: test conditions for film and sheet", and the test results are shown in Table 1 below.

[0084] Table 1 Performance test results

[0085]

[0086] Compared with Comparative Examples 1-3, the square bottom bags prepared from Examples 1-15 have higher tensile strength and elongation at break, indicating that the inner layer, the intermediate layer and the outer layer are synergized by the polylactic acid, the ethylene-vinyl alcohol copolymer and the ethylene-acrylic acid copolymer located in different layers, thereby significantly improving the toughness and strength of the square bottom bag.

[0087] Compared with Examples 3-4, the square bottom bags prepared from Examples 5-6 have higher tensile strength and elongation at break, indicating that the toughness and strength of the square bottom bag are further improved by limiting the melt index of polylactic acid at 210℃ / 2.16kg to 7-23g / 10min, and then synergizing with the ethylene-vinyl alcohol copolymer and the ethylene-acrylic acid copolymer located in different layers.

[0088] Compared with Examples 6-7, the square bottom bags prepared from Examples 8-9 have higher tensile strength and elongation at break, indicating that the toughness and strength of the square bottom bag are further improved by limiting the molar content of acrylic acid in the ethylene-acrylic acid copolymer to 7%-10%, and then synergizing with the ethylene-vinyl alcohol copolymer and the polyacrylic acid located in different layers.

[0089] Compared with Example 9, the square bottom bags prepared from Examples 10-15 have higher tensile strength and elongation at break, indicating that the toughness and strength of the square bottom bag are further improved by modifying the silica with PBAT, improving the compatibility of the silica in the polymer matrix, and improving the interlayer bonding force.

[0090] Compared with Examples 10-13, the square bottom bags prepared from Examples 14-15 have higher tensile strength and elongation at break, indicating that the toughness and strength of the square bottom bag are further improved by modifying the silica after the mass ratio of PBAT-BFX3091 to PBAT-C1200 is 2:3-3:2.

[0091] The above is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high tenacity cube corner bag characterized by, The inner layer, the middle layer and the outer layer are sequentially arranged from inside to outside. The inner layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-propylene copolymer 20-30 parts, polylactic acid 10-15 parts, and antioxidant 1-2 parts. The middle layer comprises the following components in parts by weight: ethylene-propylene copolymer 100 parts, ethylene-vinyl alcohol copolymer 25-35 parts, and silica 10-14 parts. The outer layer comprises the following components in parts by weight: polyethylene 100 parts, ethylene-acrylic acid copolymer 6-8 parts, and antioxidant 1-2 parts. The polylactic acid has a melt index of 7-23 g / 10 min at 210 ℃ / 2.16 kg. The ethylene-vinyl alcohol copolymer has a molar content of ethylene of 27%-38%. The ethylene-acrylic acid copolymer has a molar content of acrylic acid of 7%-10%.

2. A high toughness cube corner bag according to claim 1, wherein, The silica is PBAT modified silica.

3. A high toughness cube corner bag according to claim 2, wherein, The preparation method of the PBAT modified silica comprises the following steps: dissolving PBAT and mixing with silica, removing the solvent to obtain PBAT modified silica.

4. A high toughness cube corner bag according to claim 3, wherein, The mass ratio of the PBAT to the silica is 1:10-14.

5. A high toughness cube corner bag according to claim 3, wherein The model of the PBAT is BFX3091 and / or C1200.

6. A high toughness cube corner bag according to claim 5, wherein, When the model of the PBAT is BFX3091 and C1200, the mass ratio of PBAT-BFX3091 to PBAT-C1200 is 2:3-3:

2.

7. The method of making a high toughness cube corner bag of any one of claims 1-6, wherein, The method comprises the following steps: After the components of the inner layer, the middle layer and the outer layer are mixed respectively, the three layers are co-extruded and blown into a film to obtain a high-toughness square-bottom bag.

Images