Polyamide film and preparation and application of opening smooth master batch and smooth additive thereof

Abstract

The invention belongs to the field of polymer film preparation, and particularly discloses a smooth additive which comprises a caprolactam cyclic oligomer, C10-C20 fatty acid monoamide and an inorganic anti-blocking agent. The invention further discloses application of the slipping additive, the obtained polyamide film and a master batch of the polyamide film. According to the invention, the caprolactam cyclic oligomer, the fatty acid monoamide and the inorganic anti-blocking agent are innovatively combined, so that synergy can be realized accidentally, the problem of low slipping efficiency caused by the property of a polyamide polymer can be solved, and the slipping effect can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of polymer film materials, and particularly relates to the field of preparation of polyamide films. Background of the Invention

[0003] Polyamide films have excellent strength and toughness, are resistant to freezing and high temperatures, and also have good oxygen barrier properties, puncture resistance and tear resistance, good transparency and gloss, and low haze. They are particularly suitable for steaming, freezing, and vacuum packaging, and are widely used in the packaging of food, chemical products, and electronic products.

[0004] In addition to basic performance indicators such as strength, stretchability, and barrier properties, the slipperiness of polyamide films has a great impact on downstream processing. Polyamide films without any additives are prone to sticking to each other, difficult to separate, and have a large surface friction force. This will make subsequent printing and bag making difficult to carry out.

[0005] Adding a slip agent during the preparation of polyamide films can theoretically improve the slip effect and reduce the dynamic friction coefficient. For example, Chinese patent document with publication number CN111634095A discloses a reinforced composite polyamide film, which includes at least two layers of structure, and the two layers of structure are, from outside to inside in sequence, a polyamide layer (10) and a polyamide reinforced composite layer (20); the components of the polyamide reinforced composite layer (20) include: copolyamide, dendritic polyamide amine, an antiblocking agent, and a slip agent; by mass percentage, the components of the polyamide reinforced composite layer (20) include: 73% - 94.5% of copolyamide, 5% - 25% of dendritic polyamide amine, 0.3% - 1% of antiblocking agent, and 0.2% - 1% of slip agent. It is further recorded that the antiblocking agent can be inorganic particles, and the slip agent can be fatty acid amide. In addition, Chinese patent document with publication number CN110540747A discloses a similar slip agent and inorganic particle solution.

[0006] Although the prior art can improve the slip effect of polyamide films to a certain extent, polyamide is different from other film materials such as polyolefins. It belongs to a polar polymer. The slip agents used for polyolefins have good compatibility with polyamide resins, and the migration speed to the film surface is slow, and it takes a relatively long time to produce a slip effect. There is no technology for rapid slipperiness of polyamide films in the prior art.

[0007] Object of the Invention

[0008] Aiming at the problem that polyamide films are difficult to achieve rapid slipperiness, the first object of the present invention is to provide a slip additive, aiming to solve the problem that polyamide films are difficult to achieve rapid slipperiness based on the combined synergistic effect of the described components.

[0009] The second object of the present invention is to provide the preparation of the described slip additive and its application in the preparation of polyamide films.

[0010] A third object of the present invention is to provide a polyamide anti-blocking and slip masterbatch, a film containing the slip additive, and a preparation method thereof.

[0011] Due to the factors of its polymer properties, it is difficult for polyamide films to adapt to existing slip components and difficult to achieve a rapid slip effect. In view of this problem, through in-depth research, the present invention provides the following improvement solutions:

[0012] A slip additive comprising a caprolactam cyclic oligomer, a fatty acid monoamide having C 10 ~C 20 and an inorganic anti-blocking agent.

[0013] In view of the problem that the slip efficiency of polyamide films is not obvious, research by the present invention shows that innovatively combining the caprolactam cyclic oligomer, fatty acid monoamide and inorganic anti-blocking agent can unexpectedly achieve synergy, can solve the problem of low slip efficiency caused by the properties of polyamide polymers, and can improve the slip effect.

[0014] The caprolactam cyclic oligomer is at least one cyclic oligomer polymerized from 2 to 7 caprolactam monomers;

[0015] Preferably, among the caprolactam cyclic oligomers, a cyclic dimer polymerized from two caprolactam monomers and cyclic polymers formed by polymerizing three to seven caprolactam monomers, wherein the content of the cyclic dimer is 20 to 50 wt.%.

[0016] In the present invention, the caprolactam cyclic oligomer is obtained by the following preparation method: during the preparation of nylon 6 by hydrolysis ring-opening polymerization of caprolactam, nylon 6 chips are extracted with water, and the obtained extract is subjected to evaporation concentration, centrifugal filtration, water washing, vacuum drying and pulverization.

[0017] In the present invention, the fatty acid monoamide includes but is not limited to at least one of stearic acid amide and palmitic acid amide.

[0018] In the present invention, the inorganic anti-blocking agent is an inorganic powder with an average particle size of less than 10 microns;

[0019] Preferably, the inorganic anti-blocking agent includes but is not limited to at least one of silica, calcium carbonate, and glass microspheres.

[0020] For the slip additive of the present invention, the weight ratio of the caprolactam cyclic oligomer, fatty acid monoamide and inorganic anti-blocking agent is 3-8:5-10:3-10, and more preferably 4-7:5-10:3-8.

[0021] The present invention also provides the application of the described slip additive, which is used as a slip additive for preparing polyamide films and their antiblocking and slip masterbatches;

[0022] Preferably, it is mixed with a polyamide carrier resin to prepare an antiblocking and slip masterbatch for polyamide films;

[0023] Preferably, the antiblocking and slip masterbatch for polyamide films is added to polyamide to prepare polyamide films.

[0024] The present invention also provides an antiblocking and slip masterbatch for polyamide films, which comprises a polyamide carrier resin and a slip additive.

[0025] In the present invention, the polyamide carrier resin comprises at least one of polyamide 6, a binary or ternary copolyamide formed by caprolactam and nylon 66 salt, dodecanolactam or 12-aminododecanoic acid;

[0026] Preferably, in the antiblocking and slip masterbatch, the content of the slip additive is 5-30 wt.%, and further can be 10-25 wt.%.

[0027] The present invention also provides a polyamide film, which comprises a polyamide film substrate and the slip additive described in the present invention dispersed therein. Further, the polyamide film comprises a polyamide film substrate and the antiblocking and slip masterbatch described in the present invention dispersed therein.

[0028] The present invention also provides a method for preparing the described polyamide film, which is obtained by compounding polyamide and the antiblocking and slip masterbatch for film formation;

[0029] Preferably, the addition amount of the antiblocking and slip masterbatch for polyamide is 0.5-5 wt.%, preferably 1-3 wt.%.

[0030] There is no particular requirement for the relative viscosity of the polyamide, as long as it meets the requirements for film preparation. For example, its relative viscosity can be 3.5-4.5.

[0031] In the present invention, the film formation method can be well-known.

[0032] Beneficial effects

[0033] During the production of polyamide films, adding the slip additive and the slip masterbatch of the present invention can produce a slip effect in a relatively short time and remain unchanged after long-term storage. At the same time, it has little influence on the light transmittance and haze. Specific embodiments

[0034] In the present invention, the caprolactam cyclic oligomer is at least one of the cyclic oligomers of 2 to 7 caprolactam units (for example, the structure is The n is 1 to 6), which can be a by-product collected during the synthesis of nylon 6. For example, the method for obtaining the same is as follows: extracting the aqueous solution of nylon 6 slices in the industrial process of preparing nylon 6 slices by hydrolysis and ring-opening polymerization of caprolactam, concentrating the aqueous solution to a water content of about 20% by evaporation, collecting the water by centrifugation at room temperature with a centrifuge, washing the filter cake with desalted water at room temperature, and placing the washed filter cake in a vacuum drying oven, and vacuum drying the filter cake at 105°C to 125°C and a gauge pressure of -0.08MPa to -0.10MPa until the filter cake contains less than 0.5% water, thereby obtaining the caprolactam oligomer used in the present invention. In the following case, as a typical implementation example, the content of the cyclic dimer polymerized by two caprolactam monomers in the caprolactam cyclic oligomer used is 30 to 40wt.%, and the rest is a cyclic polymer formed by the polymerization of three to seven caprolactam monomers.

[0035] In the present invention, the method for preparing the masterbatch can be conventional, for example: the carrier resin slice is metered into the main feed port of the twin-screw extruder, the caprolactam oligomer, the inorganic opening agent, and the fatty acid monoamide are uniformly mixed, and then forcefully fed into the twin-screw extruder from the side feed port after metering, and then extruded into granules after melt blending, and dried in a vacuum or nitrogen environment to a water content of less than 0.1%, thereby obtaining the masterbatch of the present invention.

[0036] Example 1

[0037] Step (1): Ingredients:

[0038] Slip additives: 5 kg of spherical silica with an average particle size of 2.5 μm, 4 kg of caprolactam oligomer, and 8 kg of stearic acid amide are mixed evenly;

[0039] The carrier resin is 83 kg of polyamide 6 chips with a relative viscosity of 3.2.

[0040] Step (2): Masterbatch:

[0041] A Nanjing Ruiya Φ35mm twin-screw extruder was used, and polyamide 6 chips were added from the main feeder at a feeding rate of 8.3kg / h; the slip additive was added from the side feeder at a feeding rate of 1.7kg / h. The twin-screw extruder speed was 200rpm, and the melt was extruded into granules, and vacuum dried at 115°C for 16 hours to obtain an open slip masterbatch with a moisture content of 0.08%.

[0042] Step (3): Polyamide film:

[0043] Polyamide 6 chips with a relative viscosity of 4.0 were respectively added with 1%, 2%, and 3% by weight of the above masterbatch, and using a Φ20mm single-screw blown film machine, the above polyamide resin composition was prepared into a film. The temperatures of each section of the screw were 205°C - 260°C - 260°C in sequence starting from the feeding section, and the die head temperature was 250°C. The film thickness was 30 microns. The film was placed in an environment with a temperature of 25°C and a humidity of 50%, and the coefficient of friction was measured after placing for 0.5, 1, 24, and 72 hours respectively. The light transmittance and haze were measured after placing for 72 hours.

[0044] Example 2

[0045] Step (1): Batching:

[0046] Slip additive: It includes 10 kg of calcium carbonate with an average particle size of 6 microns, 5 kg of caprolactam oligomer, and 5 kg of palmitic acid amide, which are mixed evenly;

[0047] The carrier resin is 80 kg of polyamide 6 / 66 copolymer chips with a relative viscosity of 3.0.

[0048] Step (2): Masterbatch:

[0049] Using a Nanjing Ruia Φ35mm twin-screw extruder, the feeding speed of polyamide 6 / 66 chips is 8 kg / h, and the feeding speed of the mixed material of the slip additive is 2 kg / h. The rotational speed of the twin-screw extruder is 200 rpm, melt extrusion granulation is carried out, and vacuum drying is carried out at 115°C for 16 hours to obtain an anti-blocking and slip masterbatch with a water content of 0.07%.

[0050] Step (3): Polyamide film:

[0051] Polyamide 6 / 66 copolymer chips with a relative viscosity of 3.8 were respectively added with 1%, 2%, and 3% by weight of the above masterbatch, and using a Φ20mm single-screw blown film machine, the above polyamide resin composition was prepared into a film. The temperatures of each section of the screw were 205°C - 240°C - 240°C in sequence starting from the feeding section, and the die head temperature was 245°C. The film thickness was 30 microns, and the coefficient of friction, light transmittance, and haze were measured by the same method as in Example 1.

[0052] Example 3

[0053] Step (1): Batching:

[0054] Slip additive: It includes 8 kg of glass microspheres with an average particle size of 2 microns, 7 kg of caprolactam oligomer, and 10 kg of N-hydroxymethyl stearamide, which are mixed evenly;

[0055] The carrier resin is 75 kg of polyamide 6 chips with a relative viscosity of 3.2.

[0056] Step (2): Masterbatch:

[0057] Using a Nanjing Ruia Φ35mm twin-screw extruder, the feeding speed of polyamide 6 chips is 7.5 kg / h, and the feeding speed of the slip additive is 2.5 kg / h. The rotational speed of the twin-screw extruder is 200 rpm. The melt is extruded and pelletized, and vacuum dried at 115°C for 16 hours to obtain the anti-blocking and slip masterbatch with a water content of 0.05%.

[0058] Step (3): Polyamide film:

[0059] Polyamide 6 / chips with a relative viscosity of 3.8, respectively add 1%, 2%, and 3% of the above masterbatch by weight. Using a Φ20mm single-screw blown film machine, the above polyamide resin composition is prepared into a film. The temperatures of each section of the screw are 205°C - 260°C - 260°C in sequence starting from the feeding section, and the die head temperature is 250°C. The friction coefficient, light transmittance, and haze are tested by the same method as in Example 1.

[0060] Comparative Example 1

[0061] Compared with Example 1, the difference is only that an equal weight of talcum powder (D50 is 1.5 microns) is used to replace the caprolactam oligomer, and other operations and parameters are the same as in Example 1, and the addition amount of the masterbatch is 3%.

[0062] Comparative Example 2

[0063] Compared with Example 1, the difference is only that in the slip additive, the caprolactam oligomer is missing, and the total amount of the slip additive used and other operations and parameters are the same as in Example 1, and the addition amount of the masterbatch is 3%.

[0064] Comparative Example 3

[0065] Compared with Example 1, the difference is only that in the slip additive, the caprolactam oligomer is missing, and the missing component is supplemented by stearic acid amide. That is, the slip additive is spherical silica and stearic acid amide with a weight ratio of 5:12. The total amount of the slip additive used and other operations and parameters are the same as in Example 1, and the addition amount of the masterbatch is 3%.

[0066] Comparative Example 4

[0067] Compared with Example 1, the difference is only that ethylene bisstearamide and erucic acid amide are used instead of stearic acid amide, and the mass ratio of the two is 50 / 50. Other operations and parameters are the same as in Example 1, and the addition amount of the masterbatch is 3%.

[0068] Comparative Example 5

[0069] Compared with Example 1, the difference is only that N-octadecyl stearamide is used instead of stearic acid amide, and other operations and parameters are the same as in Example 1, and the addition amount of the masterbatch is 3%.

[0070] Comparative Example 6:

[0071] Compared with Example 1, the difference is only that in Step 3, the masterbatch described above is not added. Other operations and parameters are the same as those in Example 1.

[0072] The test data of the coefficient of friction are shown in the following table:

[0073] Coefficient of Friction Test of Films Prepared in Examples and Comparative Examples

[0074]

[0075]

[0076] From the data comparison in the above table, it can be seen that the film prepared in the example quickly produces a smoothness effect, and the smoothness effect remains good after being placed for 72 hours. The influence on the light transmittance and haze of the film is also very small. When using other types of slip agents, although an ideal smoothness can be obtained after long-term placement, the effect cannot be produced in a short time.

Claims

1. A smoothness additive, characterized in that, Containing caprolactam cyclic oligomers, fatty acid monoamides of C 10 ~C 20 and inorganic opening agents.

2. The slip additive according to claim 1, wherein The caprolactam cyclic oligomer is at least one cyclic oligomer polymerized from 2 to 7 caprolactam monomers; Preferably, among the caprolactam cyclic oligomers, a cyclic dimer polymerized from two caprolactam monomers and a cyclic polymer formed by polymerizing three to seven caprolactam monomers, wherein the content of the cyclic dimer is 20 to 50 wt.%.

3. The slip additive according to claim 1, wherein The fatty acid monoamide includes but is not limited to at least one of stearic acid amide and palmitic acid amide.

4. The slip additive according to claim 1, characterized in that, The inorganic antiblocking agent is an inorganic powder with an average particle size of less than 10 microns; Preferably, the inorganic antiblocking agent includes but is not limited to at least one of silica, calcium carbonate, and glass microspheres.

5. The smoothness additive according to any one of claims 1 to 4, characterized in that The weight ratio of the caprolactam cyclic oligomer, fatty acid monoamide, and inorganic antiblocking agent is 3 - 8:5 - 10:3 - 10, and more preferably 4 - 7:5 - 10:3 - 8.

6. Use of the slip additive according to any one of claims 1 to 4, characterized in that, Use it as a slip additive for preparing polyamide films and their antiblocking and slip masterbatches; Preferably, mix it with a polyamide carrier resin to prepare a polyamide film antiblocking and slip masterbatch; Preferably, add the polyamide film antiblocking and slip masterbatch to polyamide to prepare a polyamide film.

7. An anti-blocking and slip masterbatch for preparing polyamide films, characterized in that, It contains a polyamide carrier resin and the slip additive according to any one of claims 1 - 5.

8. The anti-blocking and slip masterbatch for preparing polyamide films according to claim 7, characterized in that, The polyamide carrier resin includes at least one of a binary or ternary copolyamide formed from polyamide 6, caprolactam, nylon 66 salt, dodecanolactam, or 12 - aminododecanoic acid; Preferably, in the antiblocking and slip masterbatch, the content of the slip additive is 5 - 30 wt.%.

9. A polyamide film, characterized in that, It contains a polyamide film substrate and the slip additive according to any one of claims 1 - 5 dispersed therein; Preferably, it contains a polyamide film substrate and the antiblocking and slip masterbatch according to any one of claims 7 - 8 dispersed therein.

10. A method for preparing the polyamide film according to claim 9, characterized in that, Compound polyamide and the antiblocking and slip masterbatch according to any one of claims 7 - 8 for film - forming treatment to obtain it; Preferably, the addition amount of the antiblocking and slip masterbatch to polyamide is 0.5 - 5 wt.%, preferably 1 - 3 wt.%.

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