Nylon 12 granular material capable of enabling pipe processing wall thickness to be stable and controllable as well as preparation method and application of nylon 12 granular material

Abstract

The invention provides nylon 12 granules capable of stabilizing and controlling the pipe processing wall thickness and a preparation method and application of the nylon 12 granules. The nylon 12 granules comprise nylon 12 matrix granules and higher fatty acid metal salt wrapping the surfaces of the nylon 12 matrix granules. The higher fatty acid metal salt accounts for 0.03-0.5% of the total mass of the nylon 12 granules, and preferably 0.05-0.3% of the total mass of the nylon 12 granules. According to the invention, the surface of the nylon 12 granular material is uniformly coated with a certain content of higher fatty acid metal salt powder, so that a nylon 12 pipe product with stable and controllable pipe processing wall thickness can be obtained. The method has the characteristics of good pipe continuous extrusion stability, high wall thickness uniformity and high extrusion linear speed, and has the advantages of simple forming process, low equipment investment and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of modified plastics, and particularly relates to a nylon 12 pellet that can make the wall thickness of pipe processing stable and controllable, and its preparation method and application. Background Art

[0002] Nylon 12 is an excellent material for automotive lightweighting, and is widely used in the field of automotive fluid transmission pipelines. It has strong irreplaceability, and its application scenarios include fuel pipelines, lubricating oil pipelines, vacuum brake pipelines, pneumatic brake pipelines, cooling pipelines, etc. Compared with metal pipes, nylon 12 pipes have obvious advantages: nylon 12 pipes are light in weight, with a density of only 1.00 - 1.03 g / cm, which can significantly reduce the vehicle's overall weight and fuel consumption; they have good flexibility, are easy to arrange, have a high degree of design freedom, and can reduce the use of joints; they have high safety, good toughness, are not easily deformed by external impacts, and have good vibration resistance, fatigue resistance, and corrosion resistance; the joints have good sealing performance and are easy to install; extrusion molding is easy and the process is simple. Compared with rubber pipes, nylon 12 pipes have the following advantages: small volume deformation, and the air brake pipes made of it can effectively reduce the vehicle's braking distance; nylon 12 pipes have thin walls, small volume, and light weight, do not affect the space layout, and have excellent aging performance; short molding cycle, energy saving; no need to add a braided layer, simple processing, thermoplastic, recyclable, meeting the requirements of low-carbon environmental protection.

[0003] Automotive pipelines generally have an outer diameter of 6 - 28 mm and a wall thickness of 0.5 - 3 mm. They are extruded and processed using a single-screw extruder in cooperation with an "O" shape, and the linear speed is usually 3 - 60 meters per minute. The continuous extrusion stability and wall thickness uniformity of the pipes are the most concerned characteristics of pipe processing enterprises. And the extrusion linear speed is related to the output per unit time, which in turn affects the output, cost, and profit margin of pipe enterprises. Therefore, pipe processing enterprises have put forward relatively high requirements for the processing performance of nylon 12 materials for automotive pipelines.

[0004] However, the continuous extrusion stability, wall thickness uniformity, and extrusion linear speed of pipes are not only directly related to the pipe forming equipment, but also have a great relationship with the nylon 12 material itself.

[0005] Chinese Patent CN215150811U discloses an extruder for producing plasticized modified nylon 12 pellets for automotive pipelines. This extruder can improve the problem of relatively large loss of plasticizer during the production process. The plasticizer entering the matrix is close to the set value of the actual liquid and the value is stable. The plasticizer is evenly dispersed, and the reliability and stability of product quality are better, and it can reduce production costs and reduce quality accidents.

[0006] Chinese Patent CN116001401A discloses a multi-layer composite pipeline material and its preparation method. This invention has excellent high-temperature resistance and long-term use performance, good strength and low-temperature toughness, and good medium resistance performance. It can be processed into pipelines of different shapes, broadening the scope of pipeline use.

[0007] Chinese Patent CN114213750A discloses a multi-layer pipeline. Through a three-layer co-extrusion process, a three-layer pipeline structure is obtained. This pipeline material and structure can not only greatly improve the heat resistance of the original pipeline to meet the performance requirements of automotive functional components in different environments. At the same time, compared with existing materials, it has a better barrier effect on the pipeline fluid being transported, which has more important practical significance.

[0008] Chinese Patent CN101973123A discloses a method for controlling the wall thickness of a hollow pipe. By providing a method for controlling the wall thickness of a hollow pipe, the outer surface and inner surface of the hollow pipe are detected, the outer concave points on the outer surface and the inner concave points on the inner surface are found, and the outer surface of the hollow pipe is pressed down at the outer surface of the hollow pipe corresponding to the inner concave points, and the outer surface of the hollow pipe is turned. This control method ensures the uniformity of the wall thickness of the hollow pipe, is simple in method and convenient in operation, can extend the service life of the hollow pipe, reduce the deviation or bending of the hollow pipe caused by the wall thickness difference problem during use, and reduce the risk and hidden dangers during use.

[0009] Although the above patents protect pipeline materials, pipe structures and manufacturing equipment, there is a lack of technical means for the source control of the stability and uniformity of pipe processing and manufacturing. That is, the uniform distribution and stable flow of the melt in the extruder are the fundamental reasons for the wall thickness stability of the pipe formed by cooling through the die at the outlet. Therefore, there are great challenges in the batch manufacturing consistency of nylon 12 pipes. Summary of the Invention

[0010] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a nylon 12 pellet and its preparation method that can make the wall thickness of the processed pipe stable and controllable. This pellet has the characteristics of good stability of continuous extrusion of the pipe, high wall thickness uniformity, and fast extrusion line speed when processing and forming the pipe, and can be used in the fields of pipe preparation such as automotive, industrial, electric power, engineering, municipal, marine, and transportation.

[0011] In the prior art, the boundary between the incompletely melted granular material and the melt in the melting and plasticizing section of a single-screw extruder is generally referred to as the melting line (or solid-liquid boundary line). The distance of this line from the center of the feeding port is generally called the melting range. For a single-screw extruder with insufficient plasticizing ability, the melting line will be more inclined towards the direction of the feeding port, that is, the melting range is short, which will further lead to weak melting and plasticizing ability. The ability of the screw groove to accommodate solid granular materials is weakened, resulting in unstable feeding at the feeding port, that is, the mass fluctuation of the granular materials fed into the screw groove per unit time is relatively large, and the melt pressure and melt quality transmitted to the die of the extruder will also fluctuate greatly accordingly, ultimately resulting in obvious fluctuations in the wall thickness of the pipe extruded from the die. Therefore, when the existing nylon 12 conventional granular materials enter the feeding port of a single-screw extruder, the phenomenon of unstable wall thickness of nylon 12 pipes often occurs due to this mechanism. In the process of the experiment of the present invention, it was unexpectedly found that nylon 12 granular materials uniformly coated with metal salts of higher fatty acids can effectively solve the above problems. The metal salts of higher fatty acids coated on the outer surface can form a uniform lubricating film on the surface of the particles in the melting and plasticizing section, thereby reducing the friction between the particles, reducing the angle of repose of the particles, and making the feeding of the particles into the screw groove more stable and uniform, ultimately making the wall thickness of the pipe extruded from the die stable and controllable.

[0012] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0013] A kind of nylon 12 granular material capable of making the wall thickness of pipe processing stable and controllable, the nylon 12 granular material comprises nylon 12 matrix particles and metal salts of higher fatty acids coated on the surface;

[0014] The metal salts of higher fatty acids account for 0.03-0.5% of the total mass of the nylon 12 granular material, such as 0.03, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5%, and preferably 0.05-0.3%.

[0015] In the present invention, the metal salts of higher fatty acids are in powder form, and their particle size (D90) is between 10nm and 100um, such as 10nm, 50nm, 100nm, 300nm, 500nm, 700nm, 1um, 5um, 10um, 20um, 40um, 60um, 80um, 100um;

[0016] Preferably, the metal salts of higher fatty acids are fatty acid metal salts with a C2-24 molecular chain;

[0017] Preferably, the metal therein is selected from metals with activity before hydrogen, preferably one or more of calcium, zinc, tin, magnesium, etc.;

[0018] Preferably, the metal salt of higher fatty acid is selected from one or more mixtures of calcium stearate, zinc stearate, stannous stearate, magnesium stearate, etc.

[0019] In the present invention, the nylon 12 matrix particles are prepared by melt extrusion granulation using a twin-screw extruder and contain the following raw materials in parts by weight:

[0020]

[0021]

[0022] Preferably, the nylon 12 resin is not particularly limited and can be a conventional choice in the art. Preferably, the viscosity is 1.5 - 2.8; more preferably, it is one or more combinations of L3000, L2000, and L1000 produced by Wanhua Chemical.

[0023] Preferably, the plasticizer is selected from one or more of p-hydroxybenzoate and arylsulfonic acid amide. Preferably, it is one or more of P-benzenesulfonamide, N-butylbenzenesulfonamide, methyl p-hydroxybenzoate, N-methylbenzenesulfonamide, ethyl p-hydroxybenzoate, octyl p-hydroxybenzoate, isocetyl p-hydroxybenzoate, n-octyl toluenesulfonamide, n-butyl benzenesulfonamide, 2-ethylhexyl benzenesulfonamide. More preferably, it is one or more of N-butylbenzenesulfonamide, methyl p-hydroxybenzoate, and octyl p-hydroxybenzoate.

[0024] Preferably, the toughening agent is selected from one or more of polyamide elastomer, polyolefin elastomer, and ethylene-acrylic acid copolymer. The toughening agent is a product already disclosed in the prior art, and there is no special requirement for its source. It can be prepared by conventional transesterification and polycondensation reactions from the above-listed raw materials based on the existing process; it can also be obtained by purchasing existing products; preferably, it is one or more of Arkema Pebax 2533, AX8900, Dow Chemical GR216, N416, N493, A560, 4170, PTW, and Mitsui Chemicals MH-5020C.

[0025] Preferably, the antioxidant is selected from one or more of copper salt antioxidants, phosphate antioxidants, hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants, and polymer antioxidants. Preferably, it is a copper salt antioxidant, such as H320, H324, H1607, H3336, H3376, H3386, AO-K, KL-36, S5050, etc.

[0026] Preferably, the light stabilizer is selected from one or more of ultraviolet absorbers, free radical scavengers, and light screening agents, preferably one or more of UV312, UV329, UV234, UV360, 770, 944, 622, and S-EED.

[0027] Preferably, the lubricant is selected from one or more of polyethylene waxes, low molecular weight esters, metal soaps, stearic acid composite esters, amide waxes, montan waxes, and low-viscosity bisphenol A epoxy resins.

[0028] Preferably, the colorant is selected from one or more of pigments, dyes, carbon black, and masterbatches.

[0029] A method for preparing nylon 12 pellets capable of stably controlling the wall thickness during pipe processing, the steps including:

[0030] Mix nylon 12 matrix pellets with a certain amount of metal salts of higher fatty acids, stir evenly, so that the metal salts of higher fatty acids are evenly coated on the surface of the nylon 12 matrix pellets, and nylon 12 pellets capable of stably controlling the wall thickness during pipe processing are obtained.

[0031] In the present invention, the dosage of the metal salts of higher fatty acids is 0.03-0.5% of the total mass of the nylon 12 matrix pellets and the metal salts of higher fatty acids, such as 0.03, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5%, preferably 0.05-0.3%.

[0032] In the present invention, the preparation method is a conventional physical blending in the field, and the mixing process is not specifically limited, as long as the metal salts of higher fatty acids can adhere to the surface of the nylon 12 matrix pellets to achieve uniform coating; for example, the equipment used in the mixing process includes but is not limited to plastic color mixers, low-speed mixers, high-speed mixers, vertical mixers, etc.; the adding methods of the metal salts of higher fatty acids include but are not limited to one-time addition, layered addition, loss-in-weight scale online addition, metering scale batch addition, etc.

[0033] The nylon 12 pellets capable of stably controlling the wall thickness during pipe processing according to the present invention have the characteristics of good stability in continuous extrusion of pipes, high wall thickness uniformity, and fast extrusion line speed during pipe processing and forming, and can be used to prepare pipes in the fields of automobiles, industry, electric power, engineering, municipal administration, ocean, transportation, etc.

[0034] The method for processing the nylon 12 pellets according to the present invention into pipes refers to using a single-screw extruder to process the nylon 12 pellets into pipes through an annular die and other conventional auxiliary mechanical devices; and evaluating the quality of the pipes by the wall thickness of the pipes;

[0035] The extrusion process is a conventional operation in the field, and the present invention does not specifically limit its steps and parameters. During the actual preparation process, those skilled in the art can select and obtain them according to actual needs with reference to the prior art.

[0036] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0037] The nylon 12 pellet material of the present invention uniformly wraps the metal salt powder of higher fatty acid, and forms a uniform lubricating film on the particle surface through the metal salt powder of higher fatty acid, thereby reducing the friction force between particles, reducing the angle of repose of particles, making the feeding of particles into the screw groove of the screw more stable and uniform, and finally making the wall thickness of the pipe extruded from the die stable and controllable. Detailed implementation manners

[0038] The following are specific examples of the present invention, which further describe the technical solution of the present invention, but the present invention includes but is not limited to these examples.

[0039] The sources of the main raw materials in the examples and comparative examples of the present invention are shown in Table 1 below. Other raw materials and reagents are obtained through commercially available channels without special instructions:

[0040] Table 1 Information on the sources of main raw materials

[0041]

[0042]

[0043] Preparation example: Preparation of nylon 12 matrix particles 1-4

[0044] Weigh the raw materials according to the components and ratios (parts by weight) in Table 2, mix them in a high-speed mixer for 5 minutes, mix the above raw materials evenly, and extrude and pelletize the mixed blend through a twin-screw extruder to obtain nylon 12 matrix particles 1-4. The screw diameter of the twin-screw extruder is 28 mm, the length-diameter ratio of the extrusion screw is 40, and the extrusion speed is 600 rpm / min.

[0045] Table 2 Components and ratios (parts by weight) of nylon 12 matrix particles 1-4

[0046]

[0047] Examples 1-5

[0048] Mix the nylon 12 matrix particles 1-4 in the foregoing preparation example with the metal salt powder of higher fatty acid according to the raw material dosage (wt%) in Table 3 in a high-speed mixer for 2 minutes, so that the metal salt powder of higher fatty acid uniformly adheres to and wraps the surface of the nylon 12 matrix particles, and obtain nylon 12 pellet materials that can make the wall thickness of pipe processing stable and controllable.

[0049] Add nylon 12 pellet that can make the wall thickness of pipe processing stable and controllable into a single-screw extruder to extrude into a pipe with a nominal wall thickness of 1 mm, and test the thickness and mechanical properties. The results are shown in Table 4.

[0050] Table 3 Types and dosages of raw materials in Examples 1-5

[0051] Example 1 Example 2 Example 3 Example 4 Example 5 Nylon 12 matrix particle 1 99.97 99.97 Nylon 12 matrix particle 2 99.95 Nylon 12 matrix particle 3 99.7 Nylon 12 matrix particle 4 99.5 Calcium stearate 0.03 - - - Magnesium stearate - 0.05 - - Zinc stearate - - 0.3 - Tin stearate - - - 0.5 Calcium palmitate 0.03

[0052] Comparative Example 1

[0053] Refer to Example 1, the difference is that after mixing according to the formulation of nylon 12 matrix pellet 1 in Table 2, no granulation is carried out, and then continue to mix according to the raw material ratio of Example 1 in Table 3 and use a twin-screw extruder for granulation. Other operations and conditions remain unchanged, and test the thickness and mechanical properties. The results are shown in Table 4.

[0054] Comparative Example 2

[0055] Refer to Example 1, the difference is that calcium stearate is replaced by oleamide, and other operations and conditions remain unchanged. Test the thickness and mechanical properties. The results are shown in Table 4.

[0056] Comparative Example 3

[0057] Refer to Example 1, the difference is that directly use nylon 12 matrix pellet 1 to process pipes, and test the thickness and mechanical properties. The results are shown in Table 4.

[0058] Comparative Example 4

[0059] Refer to Example 1, the difference is that the formulation is adjusted so that calcium stearate accounts for 0.7% of the total mass of nylon 12 pellets, and other operations and conditions remain unchanged. Test the thickness and mechanical properties. The results are shown in Table 4.

[0060] Comparative Example 5

[0061] Refer to Example 1, the difference is that the formulation is adjusted so that calcium stearate accounts for 0.02% of the total mass of nylon 12 pellets, and other operations and conditions remain unchanged. Test the thickness and mechanical properties. The results are shown in Table 4.

[0062] Each performance is tested by the following methods:

[0063] Evaluation of wall thickness stability: Measure according to GB16897-2022, take 10 adjacent pipes with a length of 1 meter for testing, and calculate the thickness limit deviation and average deviation. The thickness deviation calculation formula is as follows:

[0064] △t=t max -t min

[0065] ▲t = (t - t0) / t0 × 100%

[0066] Annotation:

[0067] △t - Thickness limit deviation;

[0068] t max — Measured maximum thickness;

[0069] t min — Measured minimum thickness;

[0070] ▲t — Average deviation;

[0071] t — Average thickness;

[0072] t0 — Nominal thickness.

[0073] According to industry standards and the requirements of general automobile OEMs, when the wall thickness of the pipe △t ≤ 0.1mm and ▲t ≤ 3%, it is considered that the wall thickness of the pipe during processing is stable and controllable.

[0074] The melt index is tested according to GB / T 3612 - 2018 of the national standard;

[0075] The impact strength at room temperature is tested according to GB / T 1843 of the national standard;

[0076] The impact strength at low temperature is tested according to GB / T 1843 of the national standard.

[0077] Table 4 Performance test results of examples and comparative examples

[0078]

[0079] It can be seen from the test results in Table 4 that through the above formula composition and preparation method, a kind of nylon 12 pellet that can make the wall thickness of the pipe during processing stable and controllable and its preparation method can be obtained. Resin components, plasticizers, toughening agents, antioxidants, etc. will not have an obvious impact on the wall thickness stability of the product, while the addition or not and the addition method of the powder of the metal salt of higher fatty acid have an obvious impact on the wall thickness stability of the product.

[0080] By comparing Examples 1 - 5 with each other, it can be found that different contents and types of the powder of the metal salt of higher fatty acid wrapped on the surface of the nylon 12 pellets have beneficial effects on both the performance and the wall thickness stability and controllability of the extruded pipe, and the differences between them are not significant.

[0081] By comparing Example 1 with Comparative Example 1, it can be seen that the addition forms of the powder of the metal salt of higher fatty acid, i.e., uniformly dispersed inside the nylon 12 pellets and uniformly wrapped on the outer surface of the nylon 12 pellets, have a great impact on the wall thickness stability and controllability of the extruded pipe, but have little impact on the performance.

[0082] It can be seen from the comparison between Example 1 and Comparative Example 2 that, compared with coating other lubricant powders on the surface of nylon 12 particles, the particles coated with metal salts of higher fatty acids have good extrusion stability for pipes, and their melt index and mechanical properties are close.

[0083] It can be seen from the comparison between Example 1 and Comparative Example 3 that, compared with not adding stearate powder, the particles coated with metal salts of higher fatty acids on the surface of nylon 12 particles have better extrusion stability for pipes, and their melt index and mechanical properties are close.

[0084] It can be seen from the comparison between Example 1 and Comparative Example 4 that after the content of metal salts of higher fatty acids exceeds 0.5%, the extrusion stability of the pipes decreases, and at the same time, other physical properties are also adversely affected.

[0085] It can be seen from the comparison between Example 1 and Comparative Example 5 that when the content of metal salts of higher fatty acids is lower than 0.03%, the beneficial effect on the extrusion stability of the pipes is not obvious.

[0086] It should be noted that the above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A nylon 12 pellet that can make the wall thickness of pipe processing stable and controllable, characterized in that, The nylon 12 pellet contains nylon 12 matrix pellets and a surface-coated metal salt of higher fatty acid; The metal salt of higher fatty acid accounts for 0.03-0.5% of the total mass of the nylon 12 pellet, preferably 0.05-0.3%.

2. The nylon 12 pellet according to claim 1, characterized in that, The metal salt of higher fatty acid is in powder form with a particle size of 10 nm-100 μm.

3. The nylon 12 pellet according to claim 1 or 2, characterized in that, The metal salt of higher fatty acid is a metal salt of fatty acid with a C12-C24 molecular chain; Preferably, the metal therein is selected from metals with activity before hydrogen, preferably one or more of calcium, zinc, tin, and magnesium.

4. The nylon 12 pellet according to any one of claims 1 to 3, characterized in that The metal salt of higher fatty acid is selected from one or more mixtures of calcium stearate, zinc stearate, tin stearate, and magnesium stearate.

5. The nylon 12 pellet according to any one of claims 1-4, characterized in that, The nylon 12 matrix pellets are prepared by melt extrusion granulation with a twin-screw extruder and contain the following raw materials in parts by weight:

6. The nylon 12 pellet according to claim 5, wherein The plasticizer is selected from one or more of p-hydroxybenzoate and arylsulfonic acid amide, preferably one or more of P-benzenesulfonamide, N-butylbenzenesulfonamide, methyl p-hydroxybenzoate, N-methylbenzenesulfonamide, ethyl p-hydroxybenzoate, octyl p-hydroxybenzoate, isocetyl p-hydroxybenzoate, n-octyl toluenesulfonamide, n-butyl benzenesulfonamide, and 2-ethylhexyl benzenesulfonamide, more preferably one or more of N-butylbenzenesulfonamide, methyl p-hydroxybenzoate, and octyl p-hydroxybenzoate.

7. The nylon 12 pellet according to claim 5, characterized in that, The toughening agent is selected from polyamide elastomer, polyolefin elastomer, and ethylene-acrylic acid copolymer; preferably one or more of Arkema Pebax 2533, AX8900, Dow Chemical GR216, N416, N493, A560, 4170, PTW, and Mitsui Chemicals MH-5020C.

8. The nylon 12 pellet according to claim 5, characterized in that, The antioxidant is selected from one or more of copper salt antioxidants, phosphate antioxidants, hindered phenol antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants, and polymer antioxidants, preferably copper salt antioxidants; and / or The light stabilizer is selected from one or more of ultraviolet absorbers, radical scavengers, and light shielding agents, preferably one or more of UV312, UV329, UV234, UV360, 770, 944, 622, and S-EED; and / or The lubricant is selected from one or more of polyethylene waxes, low molecular weight esters, metal soaps, stearic acid composite esters, amide waxes, montan waxes, and low-viscosity bisphenol A epoxy resins; and / or The colorant is selected from one or more of pigments, dyes, carbon black, and masterbatches.

9. A method for preparing nylon 12 pellets capable of stably and controllably processing the wall thickness of pipe materials according to any one of claims 1-8, characterized in that the steps Including: Mix the nylon 12 matrix pellets with a certain amount of metal salt of higher fatty acid and stir evenly to make the metal salt of higher fatty acid evenly coat the surface of the nylon 12 matrix pellets, thereby obtaining nylon 12 pellets that can stably control the wall thickness during pipe processing; Preferably, the dosage of the metal salt of higher fatty acid is 0.03-0.5% of the total mass of the nylon 12 matrix pellets and the metal salt of higher fatty acid, preferably 0.05-0.3%.

10. Use of the nylon 12 pellet capable of stably and controllably processing the wall thickness of a pipe according to any one of claims 1-8 or the nylon 12 pellet capable of stably and controllably processing the wall thickness of a pipe prepared by the method according to claim 9 in the preparation of pipes in the fields of automobiles, industry, electric power, engineering, municipal administration, ocean, and transportation.

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