A cast nylon composition and a method for making the same

Abstract

This invention discloses a casting nylon composition and its preparation method. The preparation method includes the following steps: spraying a coupling agent onto the surface of a modifier, adding it together with lactam and a catalyst into a reaction vessel, heating to 100-155°C, vacuum dehydrating for 10-40 minutes, restoring to normal pressure, adding an activator, stirring evenly, and then pouring into a mold at 150-190°C. After holding at this temperature for 5-30 minutes, the mold is opened to obtain the nylon composition. The modifier includes mica iron oxide. Further, the modifier also includes titanium dioxide. By adding an appropriate amount of modifier to casting nylon, this invention prepares a nylon composition that not only has excellent impact resistance but also excellent near-infrared light reflectivity, preventing a significant increase in the surface temperature of the casting nylon material.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, and specifically relates to a casting nylon composition and its preparation method. Background Technology

[0002] Nylon, commonly known as polyamide (PA), is a general term for thermoplastic resins containing repeating amide groups —[NHCO]— in their molecular backbone. It includes aliphatic PA, aliphatic-aromatic PA, and aromatic PA. Aliphatic PA has the most varieties, the largest production volume, and the widest applications. Cast nylon is a relatively important member of the aliphatic nylon family.

[0003] Infrared radiation, one of the many invisible rays in sunlight, was discovered by the British scientist Herschel in 1800. Also known as infrared thermal radiation, it has a strong thermal effect. Infrared radiation can be divided into three parts: near-infrared (high-frequency infrared, higher energy), with wavelengths between (3–2.5) μm and (1–0.75) μm; mid-infrared (medium-frequency infrared, moderate energy), with wavelengths between (40–25) μm and (3–2.5) μm; and far-infrared (low-frequency infrared, lower energy), with wavelengths between 1500 μm and (40–25) μm. Infrared radiation (especially near-infrared radiation) has a strong thermal effect; it can resonate with most inorganic and organic macromolecules in living organisms, accelerating their movement and causing them to rub against each other, thus generating heat.

[0004] During the hot summer months, the surface temperature of cast nylon materials exposed to sunlight for extended periods can rise significantly, reaching 70-80°C. Such high temperatures accelerate the thermo-oxidative aging process of cast nylon materials, thus shortening their service life. To avoid these problems caused by excessively high temperatures, existing technologies often add additives with infrared reflective properties during the preparation of cast nylon materials to improve their infrared reflectivity. However, most of these additives reduce the mechanical properties of the cast nylon materials, thereby affecting their use. Therefore, how to improve the high infrared reflectivity of nylon without compromising its mechanical properties is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a casting nylon composition and its preparation method, which improves the infrared reflectivity and mechanical properties of the casting nylon composite material by adding a modifier to the nylon resin, thereby solving the problems in the prior art.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a casting nylon composition includes the following steps: spraying a coupling agent onto the surface of a modifier, then adding it together with lactam and a catalyst into a reaction vessel, heating to 100-155℃, vacuum dehydrating for 10-40 minutes, restoring to normal pressure, adding an activator, stirring evenly, and then pouring into a mold at 150-190℃, keeping it at that temperature for 5-30 minutes, and then opening the mold to obtain the nylon composition; the modifier includes mica iron oxide; further, the mica iron oxide is a flake-shaped crystalline powder with a particle size of 600-2000 mesh; the weight ratio of the coupling agent, mica iron oxide, lactam, catalyst, and activator is (5-25):(25-60):1000:(1-30):(2-20).

[0008] As a preferred technical solution, the modifier further includes titanium dioxide, which is rutile titanium dioxide with an average particle size of 0.05-10μm; the weight ratio of titanium dioxide to mica iron oxide is (10-40):(25-60).

[0009] As a preferred technical solution, the coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0010] As a preferred technical solution, the lactam is selected from at least one of C4 to C12 lactams; specifically, the lactam is at least one of caprolactam, butyrolactam, octyllactam, heptanolactam, and dodecalactam.

[0011] As a preferred technical solution, the catalyst is an amide metal compound, an alkali metal, an alkali metal hydride, or an alkali metal hydroxide. The alkali metal is selected from one or more of potassium, sodium, and lithium; the alkali metal hydride is selected from one or more of potassium hydride, sodium hydride, or lithium hydride; and the alkali metal hydroxide is selected from one or more of sodium hydroxide or potassium hydroxide.

[0012] As a preferred technical solution, the activator is at least one selected from isocyanate, acetyl lactam, acyl chloride, or acid anhydride. The isocyanate is selected from one or more of toluene diisocyanate, p-toluene isocyanate, o-toluene isocyanate, or 3-isopropenyl-α,α-dimethylphenyl isocyanate; the acetyl lactam is N-acetylcaprolactam; the acyl chloride is selected from one or more of dichloroacetyl chloride, trichloroacetyl chloride, dichloropropionyl chloride, sulfonyl chloride, benzoyl chloride, or toluenesulfonyl chloride; and the acid anhydride is selected from one or more of acetic anhydride, maleic anhydride, or phthalic anhydride.

[0013] The present invention also provides a nylon composition prepared by the preparation method described above.

[0014] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0015] Cast nylon is produced through anionic bulk polymerization, where the anion is typically a reactive ion generated by a strong base abstracting hydrogen from the nitrogen atom in a lactam. The addition of 25-60 parts of mica iron oxide to the cast nylon of this invention not only significantly increases the impact resistance of the matrix but also enhances its near-infrared reflectivity. Furthermore, when 25-60 parts of mica iron oxide and 10-40 parts of nano-titanium dioxide are added to the cast nylon of this invention, the matrix exhibits not only excellent impact resistance but also superior near-infrared reflectivity, preventing a significant rise in surface temperature of the cast nylon material. Detailed Implementation

[0016] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] In the following examples and comparative examples, the catalyst was sodium hydroxide, the activator was toluene diisocyanate, and the coupling agent was silane coupling agent KH550.

[0019] Other raw materials and their manufacturers are shown below:

[0020] Caprolactam, all with a purity higher than 99%, BASF, Germany;

[0021] Mica iron oxide is a thin, crystalline powder with a particle size of 800 mesh. (Source: Anhui Mingdun Protective Materials Co., Ltd.)

[0022] The titanium dioxide is rutile titanium dioxide with an average particle size of 0.1 μm. (Ningbo Jiwei Nanotech)

[0023] The implementation of the technical solution is clearer, and the specific components used are not limited to the above-mentioned types or manufacturers. Components falling within the scope of protection of the claims can be used in the technical solution of this invention to achieve the technical effects of this invention. Furthermore, unless otherwise specified, the parts in the embodiments and comparative examples refer to parts by weight.

[0024] Example 1

[0025] Five parts of coupling agent were evenly sprayed onto the surface of 45 parts of mica iron oxide; then, together with 1000 parts of caprolactam and 5 parts of catalyst, they were added to a reaction vessel, heated to 140°C, vacuum dehydrated for 15 minutes, restored to normal pressure, and then five parts of activator were added. After stirring evenly, the mixture was poured into a mold at 180°C, kept warm for 10 minutes, and then the mold was opened to obtain the product.

[0026] Example 2

[0027] Five parts of coupling agent were evenly sprayed onto the surface of 25 parts of mica iron oxide and 10 parts of titanium dioxide. The mixture treated above, along with 1000 parts of caprolactam and 5 parts of catalyst, was added to a reaction vessel. The temperature was raised to 140°C, and the mixture was dehydrated under vacuum for 15 minutes. After restoring to normal pressure, 5 parts of activator were added, and the mixture was stirred evenly. The mixture was then poured into a mold at 180°C and kept at that temperature for 10 minutes before opening the mold to obtain the product.

[0028] Example 3

[0029] Ten parts of coupling agent were evenly sprayed onto the surface of 45 parts of mica iron oxide and 20 parts of titanium dioxide. The mixture treated above, along with 1000 parts of caprolactam and 8 parts of catalyst, was added to a reaction vessel. The temperature was raised to 135°C, and the mixture was dehydrated under vacuum for 15 minutes. After restoring to normal pressure, 12 parts of activator were added. The mixture was stirred evenly and then poured into a mold at 170°C. After holding the mixture at this temperature for 15 minutes, the mold was opened to obtain the product.

[0030] Example 4

[0031] 18 parts of coupling agent were evenly sprayed onto the surface of 55 parts of mica iron oxide and 50 parts of titanium dioxide. The mixture treated above, along with 1000 parts of caprolactam and 15 parts of catalyst, was added to a reaction vessel. The temperature was raised to 130°C, and the mixture was vacuum dehydrated for 20 minutes. After restoring to normal pressure, 18 parts of activator were added, and the mixture was stirred evenly. The mixture was then poured into a mold at 180°C and kept at that temperature for 20 minutes before opening the mold to obtain the product.

[0032] Example 5

[0033] 15 parts of coupling agent were evenly sprayed onto the surface of 30 parts of mica iron oxide and 40 parts of titanium dioxide. The mixture treated above, along with 1000 parts of caprolactam and 12 parts of catalyst, was added to a reaction vessel. The temperature was raised to 135°C, and the mixture was dehydrated under vacuum for 18 minutes. After restoring to normal pressure, 14 parts of activator were added. The mixture was stirred evenly and then poured into a mold at 165°C. After holding the mixture at this temperature for 25 minutes, the mold was opened to obtain the product.

[0034] Example 6

[0035] 12 parts of coupling agent were evenly sprayed onto the surface of 40 parts of mica iron oxide and 25 parts of titanium dioxide. The mixture treated above, along with 1000 parts of caprolactam and 10 parts of catalyst, was added to a reaction vessel. The temperature was raised to 140°C, and the mixture was dehydrated under vacuum for 16 minutes. After restoring to normal pressure, 15 parts of activator were added. The mixture was stirred evenly and then poured into a mold at 178°C. After holding the mixture at this temperature for 15 minutes, the mold was opened to obtain the product.

[0036] Comparative Example 1 (compared to Example 1)

[0037] In this comparative example, the mica iron oxide particle size is 200 nm, and other process parameters are the same as in Example 1.

[0038] Comparative Example 2 (compared to Example 1)

[0039] In this comparative example, the mica iron oxide particle size is 50 mesh, and other process parameters are the same as in Example 1.

[0040] Comparative Example 3 (compared to Example 6)

[0041] In this comparative example, no mica iron oxide was added, and the amount of titanium dioxide was 65 parts; other process parameters were the same as in Example 6.

[0042] Comparative Example 4 (compared to Example 6)

[0043] In this comparative example, the amount of mica iron oxide was 100 parts, and other process parameters were the same as in Example 6.

[0044] Comparative Example 5 (compared to Example 6)

[0045] In this comparative example, the amount of mica iron oxide was 10 parts, and other process parameters were the same as in Example 6.

[0046] Comparative Example 6 (compared to Example 6)

[0047] In this comparative example, an equal amount of iron oxide red with the same particle size (800 mesh) was used to replace mica iron oxide, and other process parameters were the same as in Example 6.

[0048] Comparative Example 7 (compared to Example 6)

[0049] In this comparative example, zinc oxide of equal particle size was used to replace mica iron oxide, and other process parameters were the same as in Example 6.

[0050] Comparative Example 8 (compared to Example 6)

[0051] In this comparative example, zinc oxide of equal particle size was used to replace titanium dioxide in equal amounts, and other process parameters were the same as in Example 6.

[0052] Comparative Example 9

[0053] The preparation method of pure cast nylon 6 is as follows: 1000 parts of caprolactam and 10 parts of catalyst are added to the reaction vessel, heated to 140°C, vacuum dehydrated for 16 minutes, restored to normal pressure, and then 15 parts of activator are added. After stirring evenly, the mixture is poured into a mold at 178°C, kept at the temperature for 15 minutes, and then the mold is opened to obtain the product.

[0054] Performance testing

[0055] The products prepared in each embodiment and comparative example were tested for relevant properties according to the following methods:

[0056] Notched impact strength test of simply supported beam: The product is prepared into a notched impact specimen of simply supported beam with a size of 127mm×13mm×3.2mm, V-notch, and notch depth of 1 / 5; the notched impact strength test is conducted in accordance with ASTM D6110-2018.

[0057] Near-infrared reflectance test: The test shall be conducted in accordance with the standard GB / T 25261-2018, wherein the near-infrared reflectance is the ratio of the reflected solar radiation energy flux in the 780nm-2500nm near-infrared band to the incident solar radiation energy flux.

[0058] The standard for testing the surface temperature of the material is room temperature of 23℃, relative humidity of 50%, and irradiation with an infrared lamp for 30 minutes at a distance of 40cm.

[0059] The performance test results are shown in Table 1.

[0060] Table 1 Performance Test Results

[0061] Test Project <![CDATA[Notched impact strength of simply supported beam (kJ / m 2 )]]> Near-infrared reflectance % Surface temperature ℃ Example 1 7.2 44.4 33.4 Example 2 6.3 49.6 31.4 Example 3 8.9 55.2 28.9 Example 4 7.4 61.8 25.3 Example 5 8.2 52.5 29.8 Example 6 8.7 54.1 29.1 Comparative Example 1 4.8 42.5 35.9 Comparative Example 2 4.5 42.8 35.8 Comparative Example 3 4.3 35.7 39.6 Comparative Example 4 4.5 54.9 29.1 Comparative Example 5 5.7 39.6 37.2 Comparative Example 6 3.9 53.3 29.9 Comparative Example 7 3.5 26.8 45.5 Comparative Example 8 7.3 40.6 36.7 Comparative Example 9 4.4 4.2 51.5

[0062] Based on the test results, adding 20-60 parts of mica iron oxide to the cast nylon of this invention can not only significantly increase the impact resistance of the matrix, but also increase the near-infrared light reflectivity of the matrix.

[0063] When 25-60 parts of mica iron oxide and 10-40 parts of nano-titanium dioxide are added to the cast nylon of this invention, the matrix not only has excellent impact resistance but also excellent near-infrared light reflectivity, which can prevent a significant rise in the surface temperature of the cast nylon material. If the amounts of mica iron oxide and nano-titanium dioxide are greater than or less than the above-defined ranges, the objective of this invention cannot be achieved.

[0064] When the particle size of mica iron oxide is reduced to 200nm, it is added to cast nylon material. Due to the small particle size, the advantages of the sheet-like shape are no longer obvious, and its impact strength and reflectivity are significantly reduced.

[0065] When the particle size of mica iron oxide increases to 50 mesh, its impact strength and near-infrared reflectivity tend to decrease when added to cast nylon materials.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a casting nylon composition, characterized in that: Includes the following steps: The coupling agent is sprayed onto the surface of the modifier, and then added to a reaction vessel along with lactam and catalyst. The temperature is raised to 100-155℃, and the mixture is vacuum dehydrated for 10-40 minutes. After restoring to normal pressure, an activator is added, and the mixture is stirred evenly. The mixture is then poured into a mold at 150-190℃ and kept at that temperature for 5-30 minutes before opening the mold to obtain the nylon composition. The modifier includes mica iron oxide. The mica iron oxide is a thin, crystalline powder with a particle size of 600-2000 mesh; The weight ratio of the coupling agent, mica iron oxide, lactam, catalyst, and activator is (5-25):(25-60):1000:(1-30):(2-20); The modifier also includes titanium dioxide, and the weight ratio of titanium dioxide to mica iron oxide is (10-40):(25-60).

2. The method for preparing the casting nylon composition according to claim 1, characterized in that: The titanium dioxide is rutile titanium dioxide with an average particle size of 0.05-10µm.

3. The method for preparing the casting nylon composition according to claim 1, characterized in that: The coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

4. The method for preparing the casting nylon composition according to claim 1, characterized in that: The lactam is at least one of caprolactam, butyrolactam, octyllactam, heptanolactam, and dodecalactam.

5. The method for preparing the casting nylon composition according to claim 1, characterized in that: The catalyst is an amide metal compound, an alkali metal, an alkali metal hydride, or an alkali metal hydroxide.

6. The method for preparing the casting nylon composition according to claim 1, characterized in that: The activator is at least one of isocyanate, acetyl lactam, acyl chloride or acid anhydride.

7. A casting nylon composition, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 6.