Preparation method of low-temperature toughened nylon film

Abstract

The invention discloses a low-temperature toughened nylon film, which is prepared by grafting maleic anhydride to a POE-PS (Polyolefin Elastomer-Polystyrene) copolymer, and the POE-PS copolymer is prepared by introducing vitreous polystyrene into POE (Polyolefin Elastomer) to obtain a toughening agent; and modifying the nylon film by using a toughening agent to prepare the modified nylon / polyethylene film. The film obtained by the invention can still maintain higher tensile property, puncture resistance and lower bag breakage rate under the low-temperature condition of-30 DEG C, and overcomes the defects that the traditional polyolefin POE flexibilizer is poor in compatibility, the strength is reduced after toughening and the like.

Description

Technical Field

[0001] The invention relates to the technical field of thin films, and in particular to a method for preparing a low-temperature toughened nylon film. Background Art

[0002] Nylon (PA) has good comprehensive properties, including mechanical properties, heat resistance, wear resistance, etc., and is a commonly used raw material for film production. However, at low temperatures (-30°C), nylon becomes brittle, and its toughness and mechanical properties are significantly reduced, making it unable to meet the packaging needs of frozen foods.

[0003] To solve the problem of nylon's low-temperature toughness, we should start with toughening. Using polyolefin elastomers (POE) is a common toughening method. The more evenly the elastomer and the toughening material are mixed, the tighter and more stable the connection is, the better the force transmission and consumption between the two phases is, and the better the toughening effect is. However, the poor compatibility of nylon and polyolefin elastomer POE will lead to a reduction in the toughening effect, and the uneven distribution will lead to a decrease in film quality. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a low-temperature toughened nylon film, which is prepared by grafting maleic anhydride onto a POE-PS copolymer, wherein the POE-PS copolymer is prepared by introducing glassy polystyrene into POE to obtain a toughening agent; and then the nylon film is modified by the toughening agent to obtain a modified nylon / polyethylene film. The film obtained by the present invention can still maintain high tensile properties, puncture resistance and low breakage rate at a low temperature of -30°C, overcoming the defects of poor compatibility of traditional polyolefin POE toughening agents and decreased strength after toughening.

[0005] To achieve the above object, the technical solution of the present invention is to design a toughening agent for low-temperature toughened nylon film, which is prepared by grafting maleic anhydride onto a POE-PS copolymer, and the POE-PS copolymer is prepared by introducing glassy polystyrene into POE.

[0006] Further, the preparation method of the POE-PS copolymer is as follows: S1. Solution preparation: dissolving POE elastomer and polystyrene in a solvent; S2. Initiation reaction: adding an initiator, heating the reaction system to 60°C~80°C, and starting the polymerization reaction; S3. Polymerization reaction: stirring at 60°C~80°C for 30-60min, polystyrene undergoes copolymerization with POE elastomer under the action of the initiator; S4. Termination reaction: after the reaction is completed, the polymerization reaction is terminated by adding a terminator; the copolymer solution is cooled, and then the copolymer is separated by solvent evaporation or precipitation; S5. Post-treatment: washing, drying, and then cutting into granules to obtain POE-PS copolymer particles; Wherein, by weight, the POE elastomer comprises 20-30 parts, polystyrene comprises 70-90 parts, solvent comprises 100-150 parts, and initiator comprises 0.1-1 parts.

[0007] Preferably, by weight, the POE elastomer comprises 25 parts, polystyrene comprises 80 parts, solvent comprises 120 parts, and initiator comprises 0.5 parts.

[0008] Furthermore, the terminator is one of carbon disulfide and nitrogen; The solvent is one of benzene and toluene; The initiator is at least one of peroxide and azo compound; preferably, the initiator is one or both of benzoyl peroxide and azobisisobutyronitrile (AIBN).

[0009] Furthermore, the preparation method of the toughening agent is as follows: Add an initiator and acetone to maleic anhydride and mix thoroughly; then pour into POE-PS copolymer particles and mix well. After the acetone evaporates, melt-extrude the mixture through a twin-screw extruder, crush it through a pelletizer, and dry it to obtain a toughening agent.

[0010] Furthermore, the inducer is benzoyl peroxide (BPO) or dichlorostilbene peroxide (DCP).

[0011] Furthermore, by weight, the maleic anhydride is 20-30 parts, the inducing agent is 0.1-2 parts, the acetone is 70-75 parts and the POE-PS copolymer particles are 25-30 parts.

[0012] Preferably, by weight, the maleic anhydride is 30 parts, the initiator is 1 part, the acetone is 70 parts and the POE-PS copolymer particles are 25 parts.

[0013] A low-temperature toughened nylon film includes a 9-layer structure, which is A, B, C, D, E, F, G, H, and I in sequence. The components of the 9 film layers are as follows: The A film layer uses BOPA and additives; The B film layer is made of LDPE and adhesive; The C film layer uses BOPA and maleic anhydride grafted POE / PS toughening agent; The D film layer is made of LDPE and adhesive; The E film layer uses BOPA and maleic anhydride grafted POE / PS toughening agent; The F film layer uses LDPE and adhesive; G film layer adopts LLDPE; The H film layer is made of LLDPE; I film layer uses mLLDPE and LDPE; The maleic anhydride grafted POE / PS toughening agent is the toughening agent according to any one of claims 1 to 6. The thicknesses of the A, B, C, D, E, F, G, H, and I film layers are 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, 8-15 μm, and 8-20 μm, respectively.

[0014] Preferably, a low-temperature toughened nylon film comprises a 9-layer structure, which is A, B, C, D, E, F, G, H, and I in sequence. The components of the 9 layers and the weight proportions of the components of each layer are as follows: A.97.5%BOPA+2.5%additive B.80% LDPE + 20% adhesive C. 50% BOPA + 50% maleic anhydride grafted POE / PS toughening agent D.80% LDPE + 20% adhesive E.50% BOPA + 50% maleic anhydride grafted POE / PS toughening agent F.80% LDPE+20% adhesive G.100%LLDPE H.100%LLDPE I.50%mLLDPE+50%LDPE; Wherein, the maleic anhydride grafted POE / PS toughening agent adopts the toughening agent described above.

[0015] Furthermore, the thicknesses of the A, B, C, D, E, F, G, H, and I film layers are 11 μm, 11 μm, 11 μm, 11 μm, 11 μm, 11 μm, 11 μm, and 12 μm, respectively.

[0016] Further, the additive is one or both of ChemTrend 4700 and Lubrizol ZT-50. Preferably, the additive is ChemTrend 4700.

[0017] Furthermore, the adhesive adopts DOW model TY1354.

[0018] A method for preparing a low-temperature toughened nylon film comprises the following steps: sucking raw material particles into a hopper, extruding the material through a die head for film blowing, cooling the material through water cooling, and entering an upper traction device, and winding the film to obtain a film sheet; the temperature of the heating zone is set to 170-250°C, the film head temperature is 190-270°C, the screw speed is 20-40 RPM, and the blowing ratio is 200%.

[0019] The advantages and beneficial effects of the present invention are: (1) The obtained film can still maintain high tensile properties, puncture resistance and low breakage rate under low temperature conditions of -30°C. It overcomes the defects of traditional polyolefin POE toughening agents such as poor compatibility and decreased strength after toughening.

[0020] (2) Introducing maleic anhydride that can react with the amide group on nylon into the POE chain to achieve in-situ compatibilization, thereby obtaining a film with high toughness and low defects. The use of toughening agents is always accompanied by a significant decrease in tensile strength while toughening. In order to solve this problem, we introduced glassy polystyrene (PS) into POE to prepare maleic anhydride-grafted POE-PS copolymer, which is used as a toughening agent in the present invention, which can toughen without losing strength. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0022] The manufacturers and brands of the raw materials used in the embodiments and comparative examples of the present invention are as follows: Maleic anhydride: MA101 BASF; POE:Exxelor POE 1010ExxonMobil; PS: STY 100BASF; BOPA: Mitsubishi BOPAMitsubishi; LDPE: Dow 210; LLDPE: Dow 7040; mLLDPE: Dow 4000Dow; Adhesive: DOW TY1354; Additive:ChemTrend 4700.

[0023] 1. Implementation Embodiment 1: A low-temperature toughened nylon film includes a 9-layer structure, which is A, B, C, D, E, F, G, H, and I in sequence. The components of the 9 layers and the weight proportions of the components of each layer are as follows: A.97.5%BOPA+2.5%additive B.80% LDPE + 20% adhesive C. 50% BOPA + 50% maleic anhydride grafted POE / PS toughening agent D.80% LDPE + 20% adhesive E.50% BOPA + 50% maleic anhydride grafted POE / PS toughening agent F.80% LDPE+20% adhesive G.100%LLDPE H.100%LLDPE I.50%mLLDPE+50%LDPE; The raw material particles are sucked into the hopper, the material is extruded through the die head to blow the film, cooled by water, and enters the upper traction device, and the film is obtained after winding; the heating zone temperature is set to 200-220℃, the film head temperature is 220-230℃, the screw speed is 35RPM, and the blowing ratio is 200%.

[0024] Among them, the thicknesses of the A, B, C, D, E, F, G, H, and I film layers are 11μm, 11μm, 11μm, 11μm, 11μm, 11μm, 11μm, 12μm respectively.

[0025] The adhesive is produced by DOW and its model is TY1354; The additive is ChemTrend 4700; The preparation steps of the maleic anhydride grafted POE / PS toughening agent are as follows: Step 1: Preparation of the POE-PS copolymer: S1. Solution preparation: dissolving POE elastomer and polystyrene in toluene; S2. Initiation reaction: adding benzoyl peroxide, heating the reaction system to 75°C, and starting the polymerization reaction; S3. Polymerization reaction: stirring at 75°C for 45 minutes, polystyrene and POE elastomer copolymerize under the action of the initiator; S4. Termination reaction: after the reaction, the polymerization reaction is terminated by introducing carbon disulfide; the copolymer solution is cooled, and then the copolymer is separated by solvent evaporation or precipitation; S5. Post-treatment: washing with deionized water, drying at 60°C for 30 minutes, and then cutting into granules to obtain POE-PS copolymer particles; Wherein, by weight, the POE elastomer is 25 parts, the polystyrene is 80 parts, the toluene solvent is 120 parts, and the initiator is 0.5 parts.

[0026] Step 2: Add benzoyl peroxide and acetone to maleic anhydride and mix thoroughly; then pour into POE-PS copolymer particles, mix and mix evenly, wait for the acetone to volatilize, melt-extrude the mixture through a twin-screw extruder, crush it through a pelletizer, and dry it to obtain a toughening agent.

[0027] In parts by weight, the maleic anhydride is 30 parts, benzoyl peroxide is 1 part, acetone is 70 parts and POE-PS copolymer particles are 25 parts.

[0028] Comparative Example 1: The only difference from Example 1 is that the toughening agent is different. The specific preparation method of the toughening agent is as follows: benzoyl peroxide and acetone are added to maleic anhydride and mixed thoroughly; then poured into the POE elastomer, mixed and mixed evenly, and after waiting for the acetone to volatilize, the mixture is melt-extruded through a twin-screw extruder, crushed through a pelletizer, and dried to obtain the toughening agent.

[0029] In parts by weight, the maleic anhydride is 30 parts, the benzoyl peroxide is 1 part, the acetone is 70 parts and the POE elastomer is 25 parts.

[0030] Comparative Example 2: The only difference from Example 1 is that the toughening agent is different. The specific preparation method of the toughening agent is as follows: benzoyl peroxide and acetone are added to maleic anhydride and mixed thoroughly; then poured into POE elastomer and polystyrene, mixed and mixed evenly, and after waiting for the acetone to volatilize, the mixture is melt-extruded through a twin-screw extruder, crushed through a pelletizer, and dried to obtain the toughening agent.

[0031] In parts by weight, the maleic anhydride is 30 parts, the benzoyl peroxide is 1 part, the acetone is 70 parts, and the mixture of POE elastomer and polystyrene is 25 parts, wherein the weight ratio of POE elastomer to polystyrene is 5:16.

[0032] Comparative Example 3: The only difference from Example 1 is that the C film layer uses 100% BOPA and no toughening agent is added to the C film layer.

[0033] Comparative Example 4: The only difference from Example 1 is that: the E film layer uses 100% BOPA; no toughening agent is added to the E film layer; Comparative Example 5: The only difference from Example 1 is that the C film layer uses 100% BOPA; the E film layer uses 100% BOPA, and no toughening agent is added to the C film layer and the E film layer.

[0034] (II) Performance test Tensile strength: measured in accordance with the provisions of standard GB / T1040.3; Elongation at break: measured in accordance with the provisions of standard GB / T1040.3; Puncture resistance: measured in accordance with the provisions of standard GB / T10004; Drop impact strength: measured in accordance with the provisions of standard GB / T9639.1; Haze: measured according to the provisions of standard GB / T2410 Tensile strength test conditions: test temperature -30℃; other indicators are tested at room temperature.

[0035] The performance test data of the films prepared by the examples and comparative examples are as follows:

[0036] The film obtained by Example 1 of the present invention can still maintain high tensile properties, puncture resistance and low breakage rate under low temperature conditions of -30°C. It overcomes the defects of poor compatibility of traditional polyolefin POE toughening agents and reduced strength after toughening. However, it can be seen from Comparative Examples 1-5 that when PS is not added to the toughening agent and POE-PS copolymer is not added, the tensile properties are significantly reduced.

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A toughening agent for low temperature toughened nylon film, characterized in that: The POE-PS copolymer is prepared by grafting maleic anhydride onto the POE-PS copolymer, and the POE-PS copolymer is prepared by introducing glassy polystyrene into POE.

2. The method for preparing a low-temperature toughened nylon film according to claim 1, characterized in that: The POE-PS copolymer preparation method is as follows: S1. Solution preparation: dissolving POE elastomer and polystyrene in a solvent; S2. Initiation reaction: adding an initiator, heating the reaction system to 60°C~80°C, and starting the polymerization reaction; S3. Polymerization reaction: stirring at 60°C~80°C for 30-60min, polystyrene undergoes copolymerization with POE elastomer under the action of the initiator; S4. Termination reaction: after the reaction is completed, the polymerization reaction is terminated by adding a terminator; the copolymer solution is cooled, and then the copolymer is separated by solvent evaporation or precipitation; S5. Post-treatment: washing, drying, and then cutting into granules to obtain POE-PS copolymer particles; Wherein, by weight, the POE elastomer comprises 20-30 parts, polystyrene comprises 70-90 parts, solvent comprises 100-150 parts, and initiator comprises 0.1-1 parts.

3. The method for preparing a low-temperature toughened nylon film according to claim 2, characterized in that: The terminator is one of carbon disulfide or nitrogen; The solvent is one of benzene and toluene; The initiator is at least one or more of peroxide and azo compound; preferably, the initiator is one or two of benzoyl peroxide and azobisisobutyronitrile.

4. The method for preparing a low-temperature toughened nylon film according to claim 3, characterized in that: The preparation method of the toughening agent is as follows: Add an initiator and acetone to maleic anhydride and mix thoroughly; then pour into POE-PS copolymer particles and mix well. After the acetone evaporates, melt-extrude the mixture through a twin-screw extruder, crush it through a pelletizer, and dry it to obtain a toughening agent.

5. The method for preparing a low-temperature toughened nylon film according to claim 4, characterized in that: The inducer is benzoyl peroxide or dichlorostilbene peroxide.

6. The method for preparing a low-temperature toughened nylon film according to claim 4, characterized in that: By weight, the maleic anhydride is 20-30 parts, the inducing agent is 0.1-2 parts, the acetone is 70-75 parts and the POE-PS copolymer particles are 25-30 parts.

7. A low temperature toughened nylon film, characterized in that: It includes 9 layers, namely A, B, C, D, E, F, G, H, and I. The components of the 9 layers are as follows: The A film layer uses BOPA and additives; The B film layer is made of LDPE and adhesive; The C film layer uses BOPA and maleic anhydride grafted POE / PS toughening agent; The D film layer is made of LDPE and adhesive; The E film layer uses BOPA and maleic anhydride grafted POE / PS toughening agent; The F film layer uses LDPE and adhesive; G film layer adopts LLDPE; The H film layer is made of LLDPE; I film layer uses mLLDPE and LDPE; Wherein, the maleic anhydride grafted POE / PS toughening agent is the toughening agent described in any one of claims 1-6.

8. The low temperature toughened nylon film according to claim 7, characterized in that: The thicknesses of the A, B, C, D, E, F, G, H, and I film layers are 8-15μm, 8-15μm, 8-15μm, 8-15μm, 8-15μm, 8-15μm, 8-15μm, 8-15μm, 8-15μm, and 8-20μm respectively.

9. The low temperature toughened nylon film according to claim 7, characterized in that: The additive is one or both of ChemTrend 4700 and Lubrizol ZT-50.

10. A method for preparing a low-temperature toughened nylon film as claimed in any one of claims 7 to 9, characterized in that: The raw material particles are sucked into the hopper, the material is extruded through the die head to blow the film, cooled by water, and enters the upper traction device, and the film is obtained after winding; the temperature of the heating zone is set to 170-250℃, the film head temperature is 190-270℃, the screw speed is 20-40 RPM, and the blowing ratio is 200%.

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