Polyamide resin and preparation method thereof

Abstract

The invention provides polyamide resin and a preparation method thereof. The preparation method comprises the following steps: mixing a polyamide 66 salt solution and an emulsion containing an anti-yellowing lubricant, and carrying out a polymerization reaction to obtain the polyamide resin, or adding an emulsion containing an anti-yellowing lubricant in the salt solution polymerization process of the polyamide 66, and carrying out polymerization reaction to obtain the polyamide resin. The preparation method of the polyamide resin is designed, and an emulsion containing an anti-yellowing lubricant is further added before or in the polycondensation process of polyamide 66 salt, so that the anti-yellowing lubricant can be uniformly dispersed in polyamide, and the polyamide resin with relatively high lubricity and relatively good yellowing resistance is obtained; the problem that adverse effects are brought to the physical and chemical properties of polyamide in the secondary processing process is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of polyamide materials, and particularly relates to a polyamide resin and a preparation method thereof. Background Art

[0002] Polyamide is one of the five major engineering plastics with excellent performance and wide application. Due to its excellent toughness, heat and cold resistance, wear resistance, non-toxicity, easy dyeing and easy molding, it is widely used in textiles, automobiles, material manufacturing and other fields.

[0003] Polyamide, especially polyamide 66, has excellent elasticity, toughness, impact resistance and corrosion resistance, but its resistance to ultraviolet light aging is poor. Polyamide molecular chains are prone to segmental breakage under long-term light exposure, resulting in molecular degradation. Therefore, its light-oxidation stability, thermal-oxidation stability and weather resistance are all poor. At present, stabilizers are often used to modify polyamide. Commonly used stabilizers are the following types: hindered phenol stabilizers, hindered amine stabilizers, phosphite stabilizers, and copper halide stabilizers. When using stabilizers to modify polyamide resin, there is often a problem of uneven dispersion of additives, which causes local yellowing of polyamide resin products during use.

[0004] CN112143224A discloses a yellowing-resistant, high heat-resistant, high dimensional stability PPA material and its preparation method. The composite material discussed in the technical scheme is composed of the following weight parts: 100 weight parts of polyphthalamide raw material, 0.5-40 weight parts of polyamide 66, 0.3-60 weight parts of filler and reinforcing agent, 4-20 weight parts of titanium dioxide, 5-40 weight parts of main flame retardant, 0.5-20 weight parts of auxiliary flame retardant, 0.1-50 weight parts of lubricant, and ultramarine, toughening agent, antioxidant, stabilizer, and coupling agent as the balance; its preparation method includes high-speed mixing, melt extrusion, injection molding and other steps.

[0005] CN116715954A discloses a high temperature resistant and anti-aging polyamide composite material and a preparation method thereof. The polyamide composite material provided by the technical solution is composed of polyamide, an anti-aging agent, a reinforcing filler, a compatibilizer, a lubricant and other additives mixed in proportion; the preparation method of the polyamide composite material includes the steps of raw material mixing; melting, extrusion; cooling; drying and pelletizing.

[0006] In the prior art, anti-yellowing additives, lubricants and other additives are generally added to polyamide resins by twin-screw blending. The secondary processing in this method has an adverse effect on the physical and chemical properties of the polyamide resin, and the anti-yellowing additives cannot be fully dispersed in the polyamide resin, resulting in unstable quality of the polyamide material, reduced anti-yellowing ability, and easy oxidation and yellowing.

[0007] Therefore, how to provide a lubricant, anti-yellowing additive and other additives that can be fully and evenly dispersed in the polyamide resin to ultimately obtain a polyamide material with high lubricity and good anti-yellowing performance has become a technical problem that needs to be solved urgently. Summary of the invention

[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a polyamide resin and a preparation method thereof. The present invention designs a preparation method for the polyamide resin, and further adds an emulsion containing a yellowing-resistant lubricant before or during the polycondensation of polyamide 66 salt, so that the yellowing-resistant lubricant can be uniformly dispersed in the polyamide, thereby obtaining a polyamide resin with good lubricity and yellowing resistance, thereby avoiding the problem that the secondary processing process has an adverse effect on the physical and chemical properties of the polyamide.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for preparing a polyamide resin, the preparation method comprising the following steps:

[0011] The polyamide 66 salt solution and the emulsion containing the yellowing-resistant lubricant are mixed and then subjected to polymerization reaction to obtain the polyamide resin;

[0012] Alternatively, an emulsion containing a yellowing-resistant lubricant is added during the polymerization process of polyamide 66 salt solution to carry out a polymerization reaction to obtain the polyamide resin.

[0013] In the prior art, lubricants cannot be added directly during the polymerization stage of polyamide 66. In order to improve the lubricity of polyamide 66, downstream manufacturers generally mix polyamide 66 and lubricants through secondary processing (adding lubricants through twin-screw extruders) or surface coating with external lubricants. Both methods will have a certain impact on the physical and chemical properties of polyamide 66. At the same time, since the external lubricant is easily oxidized, the antioxidant capacity of polyamide 66 chips is reduced.

[0014] Therefore, the present invention designs a preparation method of polyamide resin, designs that the yellowing-resistant lubricant is added to the polyamide 66 salt in the form of an emulsion, and then polymerizes, or adds the emulsion containing the yellowing-resistant lubricant during the polycondensation process of the polyamide 66 salt. On the one hand, the emulsion containing the yellowing-resistant lubricant can be uniformly dispersed in the polyamide 66, and on the other hand, the lubricant with antioxidant groups can improve the antioxidant capacity of polyamide 66, thereby solving two pain points in the industry at one time, obtaining a polyamide resin with both high lubricity and good yellowing resistance, and avoiding the occurrence of the problem that the secondary processing process has an adverse effect on the physical and chemical properties of polyamide.

[0015] At the same time, compared with granular lubricants, lubricant emulsions are more convenient to add to the polymerization kettle, and the measurement is more accurate and the formula is easy to adjust; avoiding the occurrence of problems such as uneven dispersion of the lubricant due to poor compatibility between the granular lubricant and the polyamide salt solution.

[0016] It should be noted that, in the present invention, adding the emulsion containing the anti-yellowing lubricant during the polymerization process of the polyamide 66 salt solution means adding the emulsion containing the anti-yellowing lubricant during the concentration process of the polyamide 66 salt solution.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0018] As a preferred technical solution of the present invention, the particle size of the emulsion containing the anti-yellowing lubricant is 500nm to 2000nm, for example, it can be 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 1500nm, 1600nm, 1700nm, 1800nm, 1900nm or 2000nm, etc.

[0019] The present invention limits the particle size of the emulsion containing the anti-yellowing lubricant to a specific range, so that the emulsion containing the anti-yellowing lubricant and the polyamide 66 salt solution have good compatibility, and then the anti-yellowing lubricant can be evenly dispersed in the polyamide, thereby obtaining a polyamide resin with both high lubricity and good yellowing resistance. If the particle size of the emulsion containing the anti-yellowing lubricant is too small, the dispersion of the lubricant in the polyamide 66 cannot be further improved, and energy consumption is wasted; if the particle size of the emulsion containing the anti-yellowing lubricant is too large, its compatibility with the polyamide 66 salt solution is poor, resulting in uneven dispersion of the anti-yellowing lubricant in the polyamide 66, resulting in poor performance.

[0020] In the present invention, the particle size of the emulsion containing the anti-yellowing lubricant can be measured by a laser particle size analyzer.

[0021] As a preferred technical solution of the present invention, the emulsion containing the anti-yellowing lubricant comprises the following components in percentage by weight:

[0022] Anti-yellowing lubricant 35-45%;

[0023] Dispersant 5-10%;

[0024] Solvent A Remainder.

[0025] In the present invention, in the emulsion containing the anti-yellowing lubricant, the mass percentage of the anti-yellowing lubricant can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%, etc.

[0026] In the emulsion containing the anti-yellowing lubricant, the mass percentage of the dispersant can be 5%, 6%, 7%, 8%, 9% or 10%, etc.

[0027] As a preferred technical solution of the present invention, the anti-yellowing lubricant includes hyperbranched polyamidoamine.

[0028] Preferably, the number average molecular weight of the hyperbranched polyamidoamine is 500-8000, for example, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000 or 8000.

[0029] In the present invention, the hyperbranched polyamidoamine can be a commercially available product, and its number average molecular weight can be measured by gel permeation chromatography (GPC).

[0030] Preferably, the melting temperature of the anti-yellowing lubricant is 70-95°C, for example, it may be 70°C, 72°C, 75°C, 78°C, 80°C, 81°C, 84°C, 86°C, 88°C, 92°C, 94°C or 95°C.

[0031] In the present invention, the hyperbranched polyamidoamine includes, but is not limited to, any one of Chenyuan CYD-816A, Chenyuan CYD-C604, or Chenyuan CYD-C903, or a combination of at least two thereof;

[0032] Preferably, the dispersant is selected from ionic surfactants and / or non-ionic surfactants.

[0033] Preferably, the dispersant is selected from any one or a combination of at least two of sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, polyoxyethylene stearate, polyoxyethylene wax alcohol, Span 80, emulsifier OP-10, polyvinyl alcohol octylphenyl ether, emulsifier OP-8, emulsifier OP-7, sodium oleate, polyoxyethylene ether, and polyethylene glycol fatty acid ester;

[0034] Preferably, the solvent A comprises water.

[0035] As a preferred technical solution of the present invention, the emulsion containing the anti-yellowing lubricant is prepared by the following method, which comprises the following steps:

[0036] The molten anti-yellowing lubricant, dispersant and solvent are mixed and sheared at a high speed to obtain the emulsion containing the anti-yellowing lubricant.

[0037] Preferably, the mixing temperature is 70-95°C, for example, it can be 70°C, 72°C, 75°C, 78°C, 80°C, 81°C, 84°C, 86°C, 88°C, 92°C, 94°C or 95°C, etc.

[0038] Preferably, the rotation speed of the high-speed shearing is 5000rpm-8000rpm, for example, it can be 5000rpm, 5200rpm, 5500rpm, 5700rpm, 6000rpm, 6300rpm, 6500rpm, 6800rpm, 7000rpm, 7200rpm, 7400rpm, 7600rpm, 7800rpm or 8000rpm, etc.

[0039] The invention designs the rotation speed of high-speed shearing within a specific range, thereby preparing an emulsion containing a yellowing-resistant lubricant with a specific particle size range, and finally preparing a polyamide resin with excellent performance.

[0040] Preferably, the high-speed shearing time is 30 min-50 min, for example, it can be 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, 42 min, 44 min, 46 min, 48 min or 50 min.

[0041] As a preferred technical solution of the present invention, the polyamide 66 salt solution is prepared by the following method, which comprises the following steps:

[0042] Dissolving hexamethylenediamine and adipic acid in solvent B, neutralizing and forming salts, and obtaining the polyamide 66 salt solution;

[0043] Preferably, the molar ratio of hexamethylenediamine to adipic acid is 1:(0.8-0.9), for example, it can be 1:0.8, 1:0.81, 1:0.82, 1:0.83, 1:0.84, 1:0.85, 1:0.86, 1:0.87, 1:0.88, 1:0.89 or 1:0.9, etc.

[0044] Preferably, the mass ratio of hexamethylenediamine to solvent B is 1:(1.5-3.4), for example, it can be 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3.0, 1:3.2 or 1:3.4, etc.

[0045] Preferably, the solvent B comprises water;

[0046] Preferably, the neutralization temperature for salt formation is 40-70°C (for example, 40°C, 43°C, 46°C, 49°C, 52°C, 55°C, 57°C, 60°C, 63°C, 66°C, 68°C or 70°C, etc.), and the time is 10-40min (for example, 10min, 12min, 15min, 18min, 20min, 23min, 25min, 27min, 30min, 33min, 36min, 38min or 40min, etc.).

[0047] As a preferred technical solution of the present invention, the raw materials for preparing the polyamide resin include the following components in percentage by weight:

[0048] Polyamide 66 salt 50-60%;

[0049] Emulsion containing yellowing-resistant lubricant 0.25-0.75%;

[0050] Solvent Residue.

[0051] In the present invention, by designing the amount of the emulsion containing the anti-yellowing lubricant in the raw material for preparing the polyamide resin to be within a specific range, the content of the anti-yellowing lubricant in the polyamide resin finally prepared can be regulated to be within a specific range, thereby preparing a polyamide resin with excellent performance. If the amount of the emulsion containing the anti-yellowing lubricant in the raw material for preparing the polyamide resin is too small, the content of the anti-yellowing lubricant in the polyamide resin finally prepared will be too small, making the anti-yellowing performance and lubricating performance of the polyamide resin both poor; if the amount of the emulsion containing the anti-yellowing lubricant in the raw material for preparing the polyamide resin is too large, the compatibility of the polyamide 66 salt solution and the emulsion containing the anti-yellowing lubricant during the polymerization process will be poor, and the anti-yellowing performance and lubricating performance of the prepared polyamide resin will also be poor.

[0052] In the present invention, the mass percentage of the polyamide 66 salt in the raw material for preparing the polyamide resin can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60%, etc.

[0053] In the raw material for preparing the polyamide resin, the mass percentage of the emulsion containing the anti-yellowing lubricant can be 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.70% or 0.75%, etc.

[0054] As a preferred technical solution of the present invention, the polymerization reaction includes a concentration step, a pressure maintaining step, a pressure reducing step and a stamping step.

[0055] Preferably, the temperature of the concentration step is 145°C–165°C (for example, it may be 145°C, 146°C, 148°C, 150°C, 152°C, 155°C, 157°C, 158°C, 160°C, 163°C or 165°C, etc.), the pressure is 0.20MPa–0.30MPa (for example, it may be 0.20MPa, 0.21MPa, 0.22MPa, 0.23MPa, 0.24MPa, 0.25MPa, 0.26MPa, 0.27MPa, 0.28MPa, 0.29MPa or 0.30MPa, etc.), and the time is 30min–60min (for example, it may be 30min, 33min, 36min, 39min, 42min, 45min, 48min, 51min, 54min, 57min or 60min, etc.).

[0056] Preferably, the pressure of the pressure-holding step is 1.60MPa-1.80MPa (for example, it can be 1.60MPa, 1.62MPa, 1.64MPa, 1.66MPa, 1.68MPa, 1.70MPa, 1.72MPa, 1.74MPa, 1.76MPa, 1.78MPa or 1.80MPa, etc.), and the time is 30min-60min (for example, it can be 30min, 33min, 36min, 39min, 42min, 45min, 48min, 51min, 54min, 57min or 60min, etc.).

[0057] Preferably, the depressurization step is: when the temperature reaches 255°C-270°C (for example, it can be 255°C, 256°C, 258°C, 260°C, 262°C, 264°C, 266°C, 268°C or 270°C, etc.), the pressure is released to 0 MPa within 30min-60min (for example, it can be 30min, 33min, 36min, 39min, 42min, 45min, 48min, 51min, 54min, 57min or 60min, etc.), and at 3m in (for example, it can be 0.5min, 1min, 1.5min, 2min, 2.5min or 3min, etc.), the pressure is pumped to -0.01MPa–-0.06MPa (for example, it can be -0.01MPa, -0.015MPa, -0.02MPa, -0.025MPa, -0.03MPa, -0.035MPa, -0.04MPa, -0.045MPa, -0.05MPa, -0.055MPa or -0.06MPa, etc.).

[0058] Preferably, the stamping step is: when the system temperature is 270°C-280°C (for example, it can be 270°C, 271°C, 272°C, 273°C, 274°C, 275°C, 276°C, 277°C, 278°C, 279°C or 280°C, etc.), stamping to 0.20MPa-0.80MPa (for example, it can be 0.20MPa, 0.25MPa, 0.30MPa, 0.35MPa, 0.40MPa, 0.45MPa, 0.50MPa, 0.55MPa, 0.60MPa, 0.65MPa, 0.70MPa, 0.75MPa or 0.80MPa, etc.).

[0059] Preferably, the polymerization further includes a post-processing step, and the post-processing method includes cooling and pelletizing.

[0060] As a preferred technical solution of the present invention, the preparation method specifically comprises the following steps:

[0061] After mixing the polyamide 66 salt solution and the emulsion containing the yellowing-resistant lubricant, the mixture is concentrated at 145°C-165°C and 0.20MPa-0.30MPa for 30min-60min, and then the pressure is increased to 1.60MPa-1.80MPa, and the pressure is maintained for 30min-60min. When the system temperature reaches 255°C-270°C, the pressure is released to 0MPa within 30min-60min, and the pressure in the kettle is pumped to -0.01MPa--0.06MPa within 3min. When the system temperature is 270°C-280°C, the pressure is pressed into the kettle to 0.2MPa-0.8MPa, and the mixture is cooled and granulated to obtain the polyamide resin;

[0062] Alternatively, the polyamide 66 salt solution is concentrated at 145°C-165°C and 0.20MPa-0.30MPa for 30min-60min, an emulsion containing an anti-yellowing lubricant is added during the concentration process, and then the pressure is increased to 1.60MPa-1.80MPa and maintained for 30min-60min. When the system temperature reaches 255°C-270°C, the pressure is released to 0MPa within 30min-60min, and the pressure in the kettle is pumped to -0.01MPa--0.06MPa within 3min. When the system temperature is 270°C-280°C, the pressure is punched into the kettle to 0.2MPa-0.8MPa, cooled and granulated to obtain the polyamide resin.

[0063] In a second aspect, the present invention provides a polyamide resin prepared by the preparation method described in the first aspect.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] (1) The present invention designs a method for preparing a polyamide resin, and further adds an emulsion containing an anti-yellowing lubricant before or during the polycondensation of polyamide 66 salt, so that the anti-yellowing lubricant can be uniformly dispersed in the polyamide, thereby obtaining a polyamide resin having good lubricity and good anti-yellowing properties, thereby avoiding the problem of adverse effects on the physical and chemical properties of the polyamide during the secondary processing process. The melt index is 102-118 g / 10 min, the cooling time is 3-8 s, the yellow index of 0 h is -8, the yellow index of 8 h is -2.4 to -3.8, the yellow index of 16 h is 0.9 to 2.1, and the yellow index of 24 h is 2.8 to 4.7.

[0066] (2) The present invention further improves the comprehensive performance of the polyamide resin by further optimizing the particle size and dosage of the emulsion containing the anti-yellowing lubricant within a specific range, wherein the melt index is 106-116 g / 10 min, the cooling time is 3-6 s, the yellow index of 8 h is -2.7 to -3.6, the yellow index of 16 h is 0.9 to 2.0, and the yellow index of 24 h is 2.8 to 4.2. DETAILED DESCRIPTION

[0067] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0068] The sources of some components in the embodiments and comparative examples are as follows:

[0069] Hyperbranched polyamidoamine 1: Chenyuan CYD-816A;

[0070] Hyperbranched polyamidoamine 2: Chenyuan CYD-C604;

[0071] Hyperbranched polyamidoamine 3: Chenyuan CYD-C903.

[0072] Preparation Example 1

[0073] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The emulsion containing a yellowing-resistant lubricant comprises the following components in percentage by weight:

[0074] Hyperbranched polyamidoamine 40%;

[0075] Dispersant 8%;

[0076] Deionized water 52%;

[0077] The hyperbranched polyamidoamine is composed of Chenyuan CYD-816A and Chenyuan CYD-C604 in a mass ratio of 1:2;

[0078] The dispersant is composed of sodium dodecylbenzene sulfonate and Span 80 in a mass ratio of 1:1.

[0079] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0080] The hyperbranched polyamide amine was melted at 80°C, and a dispersant and deionized water at 80°C were added to the molten hyperbranched polyamide amine. The emulsion containing the yellowing-resistant lubricant was obtained by high-speed shearing at 6000 rpm for 40 minutes using a high-speed shearing machine. The particle size was tested by a laser particle size analyzer, and the particle size was measured to be 600 nm.

[0081] Preparation Example 2

[0082] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The emulsion containing a yellowing-resistant lubricant comprises the following components in percentage by weight:

[0083] Hyperbranched polyamidoamine 38%;

[0084] Dispersant 7%;

[0085] Deionized water 55%;

[0086] The hyperbranched polyamidoamine is composed of Chenyuan CYD-816A and Chenyuan CYD-C903 in a mass ratio of 1:3;

[0087] The dispersant is composed of sodium dodecylbenzene sulfonate and emulsifier OP-10 in a mass ratio of 1:2.

[0088] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0089] The hyperbranched polyamide amine was melted at 85°C, and a dispersant and deionized water at a temperature of 80°C were added to the molten hyperbranched polyamide amine. A high-speed shearing machine was used to perform high-speed shearing at 7000 rpm for 45 minutes to obtain the emulsion containing the anti-yellowing lubricant. The particle size was tested using a laser particle size analyzer, and the particle size was measured to be 550 nm.

[0090] Preparation Example 3

[0091] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The specific composition of the emulsion containing a yellowing-resistant lubricant is the same as that of Preparation Example 1;

[0092] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0093] The hyperbranched polyamide amine was melted at 80°C, and a dispersant and deionized water at a temperature of 80°C were added to the molten hyperbranched polyamide amine. A high-speed shearing machine was used to perform high-speed shearing at 5000 rpm for 40 minutes to obtain the emulsion containing the anti-yellowing lubricant. The particle size was tested using a laser particle size analyzer, and the particle size was measured to be 1800 nm.

[0094] Preparation Example 4

[0095] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The specific composition of the emulsion containing a yellowing-resistant lubricant is the same as that of Preparation Example 1;

[0096] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0097] The hyperbranched polyamide amine was melted at 80°C, and a dispersant and deionized water at a temperature of 80°C were added to the molten hyperbranched polyamide amine. A high-speed shearing machine was used to high-speed shear for 50 minutes at 6500 rpm to obtain the emulsion containing the anti-yellowing lubricant. The particle size was tested by a laser particle size analyzer, and the particle size was measured to be 580 nm.

[0098] Preparation Example 5

[0099] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The specific composition of the emulsion containing a yellowing-resistant lubricant is the same as that of Preparation Example 1;

[0100] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0101] The hyperbranched polyamide amine was melted at 80°C, and a dispersant and deionized water at a temperature of 80°C were added to the molten hyperbranched polyamide amine. A high-speed shearing machine was used to high-speed shear for 50 minutes at 9000 rpm to obtain the emulsion containing the yellowing-resistant lubricant. The particle size was tested by a laser particle size analyzer, and the particle size was measured to be 410 nm.

[0102] Preparation Example 6

[0103] This preparation example provides an emulsion containing a yellowing-resistant lubricant and a preparation method thereof. The specific composition of the emulsion containing a yellowing-resistant lubricant is the same as that of Preparation Example 1;

[0104] The preparation method of the above-mentioned emulsion containing the yellowing-resistant lubricant is as follows:

[0105] The hyperbranched polyamide amine was melted at 80°C, a dispersant and deionized water at 80°C were added to the molten hyperbranched polyamide amine, and a high-speed shearing machine was used to perform high-speed shearing at 4000 rpm for 30-50 minutes to obtain the emulsion containing the anti-yellowing lubricant. The particle size was tested by a laser particle size analyzer, and the particle size was measured to be 2300 nm.

[0106] Preparation Example 7

[0107] This preparation example provides a polyamide 66 salt solution and a preparation method thereof, and the preparation method is as follows:

[0108] Hexamethylenediamine (300 g) and adipic acid (320 g) were dissolved in deionized water (750 g), neutralized to form salt at 60° C., and reacted for 30 minutes to obtain the polyamide 66 salt solution.

[0109] Examples 1-12

[0110] Examples 1-12 respectively provide a polyamide resin and a preparation method thereof. The specific composition of the raw materials for preparing the polyamide resin is shown in Tables 1 and 2 below. The amount of each component in Tables 1 and 2 is in parts by weight.

[0111] The preparation methods of the polyamide resins provided in Examples 1 and 3-12 are as follows:

[0112] The polyamide 66 salt solution and the emulsion containing the yellowing-resistant lubricant are mixed uniformly, concentrated at 145°C and 0.25MPa for 55 minutes, then the pressure is increased to 1.70MPa and maintained for 55 minutes. When the system temperature reaches 263°C, the pressure is released to 0MPa within 45 minutes, and the pressure in the kettle is reduced to -0.03MPa within 3 minutes. When the system temperature is 272°C, the pressure is pressed into the kettle to 0.3MPa, cooled and granulated to obtain the polyamide resin.

[0113] The preparation method of the polyamide resin provided in Example 2 is as follows:

[0114] The polyamide 66 salt solution is concentrated at 145°C-165°C and 0.25MPa for 55 minutes. During the concentration process, an emulsion containing an anti-yellowing lubricant is added, and then the pressure is increased to 1.70MPa and maintained for 55 minutes. When the system temperature reaches 263°C, the pressure is released to 0MPa within 45 minutes, and the pressure in the kettle is reduced to -0.03MPa within 3 minutes. When the system temperature is 272°C, the pressure is pressed into the kettle to 0.3MPa, cooled and granulated to obtain the polyamide resin.

[0115] Table 1

[0116]

[0117] Table 2

[0118]

[0119] Comparative Example 1

[0120] This comparative example provides a polyamide resin, which is different from Example 1 only in that the emulsion containing the anti-yellowing lubricant is not used, and other conditions are the same as those of Example 1.

[0121] Comparative Example 2

[0122] This comparative example provides a polyamide resin, wherein the raw materials for preparing the polyamide resin include a polyamide 66 salt solution and a hyperbranched polyamide amine (composed of Chenyuan CYD-816A and Chenyuan CYD-C604 in a mass ratio of 1:2);

[0123] The mass ratio of polyamide 66 salt to hyperbranched polyamide amine is 55:0.14.

[0124] A polyamide 66 salt solution with a mass concentration of 55% (containing 55 parts by weight of polyamide) was concentrated at 15°C and 0.25MPa for 55 minutes, then the pressure was increased to 1.70MPa and maintained for 55 minutes. When the system temperature reached 263°C, the pressure was reduced to 0MPa within 45 minutes, and the pressure in the kettle was reduced to -0.03MPa within 3 minutes. When the system temperature was 272°C, the pressure was pressed into the kettle to 0.3MPa, cooled and granulated to obtain polyamide;

[0125] The obtained polyamide and hyperbranched polyamidoamine (0.14 parts by weight) are passed through a screw extruder for melt granulation to obtain the polyamide resin;

[0126] Among them, the melt granulation process using a screw extruder includes six temperature zones, and the temperatures of the six temperature zones are 130°C, 265°C, 268°C, 273°C, 275°C, and 278°C respectively.

[0127] The properties of the polyamide resins provided in the above embodiments and comparative examples were tested, and the specific testing methods are as follows:

[0128] Melt index (g / 10min): Tested according to GB / T 3682.1-2018 "Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic thermoplastics". The larger the melt index, the better the product fluidity and lubricity;

[0129] Cooling time (s): The test was conducted using a Haitian MA900III / 280 injection molding machine with the following settings: holding pressure 52MPa, holding time 8.5s, injection pressure 50MPa. The cooling time is the time from molding to cooling and demolding after injection into the mold. The faster the molding and demolding time, the better the lubricity of the product.

[0130] Yellowness Index: Determined according to GB / T 39822-2021 "Determination of Plastic Yellowness Index and Its Change Value".

[0131] The above performance test results are shown in Table 3 below:

[0132] Table 3

[0133]

[0134]

[0135] As can be seen from the above content, the present invention designs a preparation method for polyamide resin, and further adds an emulsion containing a yellowing-resistant lubricant before or during the polycondensation of polyamide 66 salt, so that the yellowing-resistant lubricant can be uniformly dispersed in the polyamide, thereby obtaining a polyamide resin with good lubricity and good yellowing resistance, avoiding the occurrence of adverse effects on the physical and chemical properties of polyamide during the secondary processing process. The melt index is 102-118g / 10min, the cooling time is 3-8s, the yellow index of 0h is -8, the yellow index of 8h is -2.4 to -3.8, the yellow index of 16h is 0.9 to 2.1, and the yellow index of 24h is 2.8 to 4.7.

[0136] By comparing Example 1, Examples 5-6 with Examples 7-8, and by comparing Example 1, Examples 9-10 with Examples 11-12, the present invention further improves the comprehensive properties of the polyamide resin by further optimizing the particle size and dosage of the emulsion containing the anti-yellowing lubricant within a specific range, and the melt index is 106-116 g / 10 min, the cooling time is 3-6 s, the yellow index of 8 h is -2.7 to -3.6, the yellow index of 16 h is 0.9 to 2.0, and the yellow index of 24 h is 2.8 to 4.2.

[0137] By comparing Examples 1-12 with Comparative Examples 2-3, it can be seen that the present invention obtains a polyamide resin with high yellowing resistance by adding an emulsion containing an anti-yellowing lubricant during the polycondensation process of polyamide 66 salt, thereby avoiding the problem of adverse effects on the physical and chemical properties of polyamide during the secondary processing process.

[0138] In summary, the present invention designs a preparation method for polyamide resin, and further adds an emulsion containing an anti-yellowing lubricant during the polycondensation process of polyamide 66 salt, so that the anti-yellowing lubricant can be uniformly dispersed in the polyamide, thereby obtaining a polyamide resin with high anti-yellowing performance.

[0139] The applicant declares that the present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a polyamide resin, characterized in that: The preparation method comprises the following steps: The polyamide 66 salt solution and the emulsion containing the yellowing-resistant lubricant are mixed and then subjected to polymerization reaction to obtain the polyamide resin; Alternatively, an emulsion containing a yellowing-resistant lubricant is added during the polymerization process of polyamide 66 salt solution to carry out a polymerization reaction to obtain the polyamide resin.

2. The method for preparing a polyamide resin according to claim 1, wherein The particle size of the emulsion containing the anti-yellowing lubricant is 500nm to 2000nm.

3. The method for preparing a polyamide resin according to claim 1 or 2, characterized in that: The emulsion containing the anti-yellowing lubricant comprises the following components in percentage by weight: Anti-yellowing lubricant 35-45%; Dispersant 5-10%; Solvent A balance.

4. The method for preparing a polyamide resin according to claim 3, wherein: The anti-yellowing lubricant comprises a hyperbranched polyamidoamine; Preferably, the number average molecular weight of the hyperbranched polyamidoamine is 500-8000; Preferably, the melting temperature of the anti-yellowing lubricant is 70-95°C; Preferably, the dispersant is selected from ionic surfactants and / or nonionic surfactants; Preferably, the solvent A comprises water.

5. The method for preparing a polyamide resin according to claim 3, characterized in that: The emulsion containing the anti-yellowing lubricant is prepared by the following method, which comprises the following steps: The molten anti-yellowing lubricant, dispersant and solvent are mixed and sheared at high speed to obtain the emulsion containing the anti-yellowing lubricant; Preferably, the mixing temperature is 70-95°C; Preferably, the rotation speed of the high-speed shearing is 5000rpm-8000rpm; Preferably, the high-speed shearing time is 30 min-50 min.

6. The method for preparing a polyamide resin according to any one of claims 1 to 5, characterized in that: The polyamide 66 salt solution is prepared by the following method, which comprises the following steps: Dissolving hexamethylenediamine and adipic acid in solvent B, neutralizing and forming salts, and obtaining the polyamide 66 salt solution; Preferably, the molar ratio of hexamethylenediamine to adipic acid is 1:(0.8-0.9); Preferably, the mass ratio of hexamethylenediamine to solvent B is 1:(1.5-3.4); Preferably, the solvent B comprises water; Preferably, the temperature of the neutralization to form salt is 40-70°C and the time is 10-40 minutes.

7. The method for preparing a polyamide resin according to any one of claims 1 to 6, characterized in that: The raw materials for preparing the polyamide resin include the following components in percentage by weight: Polyamide 66 salt 50-60%; Emulsion containing yellowing-resistant lubricant 0.25-0.75%; Solvent Residue.

8. The method for preparing a polyamide resin according to any one of claims 1 to 6, characterized in that: The polymerization reaction comprises a concentration step, a pressure maintaining step, a pressure reducing step and a stamping step; Preferably, the temperature of the concentration step is 145°C-165°C, the pressure is 0.20MPa-0.30MPa, and the time is 30min-60min; Preferably, the pressure of the pressure-maintaining step is 1.60 MPa-1.80 MPa, and the time is 30 min-60 min; Preferably, the depressurization step is: when the temperature reaches 255°C-270°C, the pressure is reduced to 0 MPa within 30min-60min, and the pressure is reduced to -0.01MPa--0.06MPa within 3min; Preferably, the stamping step is: when the system temperature is 270°C-280°C, stamping to 0.20MPa-0.80MPa; Preferably, the polymerization further includes a post-processing step, and the post-processing method includes cooling and pelletizing.

9. The method for preparing a polyamide resin according to any one of claims 1 to 8, characterized in that: The preparation method specifically comprises the following steps: After mixing the polyamide 66 salt solution and the emulsion containing the yellowing-resistant lubricant, the mixture is concentrated at 145°C-165°C and 0.20MPa-0.30MPa for 30min-60min, and then the pressure is increased to 1.60MPa-1.80MPa, and the pressure is maintained for 30min-60min. When the system temperature reaches 255°C-270°C, the pressure is released to 0MPa within 30min-60min, and the pressure in the kettle is pumped to -0.01MPa--0.06MPa within 3min. When the system temperature is 270°C-280°C, the pressure is pressed into the kettle to 0.2MPa-0.8MPa, and the mixture is cooled and granulated to obtain the polyamide resin; Alternatively, the polyamide 66 salt solution is concentrated at 145°C-165°C and 0.20MPa-0.30MPa for 30min-60min, an emulsion containing an anti-yellowing lubricant is added during the concentration process, and then the pressure is increased to 1.60MPa-1.80MPa and maintained for 30min-60min. When the system temperature reaches 255°C-270°C, the pressure is released to 0MPa within 30min-60min, and the pressure in the kettle is pumped to -0.01MPa--0.06MPa within 3min. When the system temperature is 270°C-280°C, the pressure is punched into the kettle to 0.2MPa-0.8MPa, cooled and granulated to obtain the polyamide resin.

10. A polyamide resin prepared by the preparation method according to any one of claims 1 to 9.

Images