1. A process for the preparation of a polyamide elastomer, characterized in that it comprises the following steps:

s1: adding lactam, aminocaproic acid and diacid into a reactor, heating under the protection of nitrogen, and mechanically stirring under normal pressure;

s2: continuously adding polysiloxane, heating, adding a catalyst, vacuumizing, and mechanically stirring;

s3: extracting with boiling water, and drying to obtain the polyamide elastomer.

2. The method of claim 1, wherein: in the step S2, the catalyst is titanium dioxide, antimony trioxide or tetrabutyl titanate.

3. The method of claim 1, wherein: the lactam is caprolactam, undecanolactam or laurolactam.

4. The method of claim 1, wherein: the diacid is malonic acid or succinic acid or glutaric acid or adipic acid or cyclohexanedicarboxylic acid or dodecanedioic acid or terephthalic acid or isophthalic acid.

5. The method of claim 1, wherein: the polysiloxane has the structural formula:

wherein R1, R2, R3 and R4 are independently C1-C10 alkyl, cycloalkyl or aromatic groups and derivatives thereof.

6. The method of claim 1, wherein: the number average molecular weight of the polysiloxane was 1000-5000.

7. The method of claim 1, wherein: according to the weight portion, the polysiloxane accounts for 10-70 portions of the total weight, the lactam accounts for 30-90 portions of the total weight, the aminocaproic acid accounts for 0.5-1.5 portions of the total weight, and the catalyst accounts for 0.5-2.5 portions of the total weight.

8. The method of claim 1, wherein: in the step S1, the temperature is raised to 190 ℃ and 230 ℃, and mechanical stirring is carried out for 1-2.5h under normal pressure.

9. The method of claim 1, wherein: in the step S2, the temperature is raised to 240 ℃ and 260 ℃, the catalyst is added, the vacuum pumping is carried out until the pressure is 50-5000Pa, and the mechanical stirring is carried out for 1-3 h.

Background

Thermoplastic elastomers (TPEs) are a unique class of polymers that can exhibit the physical properties of rubber, yet can be processed as thermoplastics. TPEs have become commercially important due to the cost savings and manufacturing simplicity associated with rapid, reversible thermoplastic processing. TPE is gradually replacing vulcanized rubber in the fields of sealing rings, gaskets, industrial hoses and footwear. The thermoplastic polyamide elastomer is a linear block copolymer consisting of polyamide hard segments and polyether or polyester soft segments, and has the characteristics of high tensile strength, good elastic recovery, high low-temperature impact strength, excellent low-temperature resistance and the like. The existing technology for preparing thermoplastic polylactam elastomer mostly adopts hydrolytic ring opening, high-pressure equipment is needed for preventing water evaporation, the cost is high, and the control is not easy.

Disclosure of Invention

In order to solve the technical problems, the preparation method of the polyamide elastomer adopts aminocaproic acid as a ring-opening agent, can react under normal pressure, solves the problem of high cost of a high-pressure device, and has the characteristics of simple and convenient operation, low cost, easy control and the like. The polysiloxane is used as a soft segment, so that the elastomer can have the performances of weather resistance, ageing resistance, hydrophobicity, physiological inertia, high and low temperature resistance and the like, and can be used as a compatilizer for blending nylon and silicon rubber.

The technical scheme of the invention is as follows:

a method of preparing a polyamide elastomer, the method comprising the steps of:

s1: adding lactam, aminocaproic acid and diacid into a reactor, heating under the protection of nitrogen, and mechanically stirring under normal pressure;

s2: continuously adding polysiloxane, heating, adding a catalyst, vacuumizing, and mechanically stirring;

s3: extracting with boiling water, and drying to obtain the polyamide elastomer.

Preferably, in step S2, the catalyst is titanium dioxide, antimony trioxide or tetrabutyl titanate.

Preferably, the lactam is caprolactam, undecanolactam or laurolactam.

Preferably, the diacid is malonic acid or succinic acid or glutaric acid or adipic acid or cyclohexanedicarboxylic acid or dodecanedioic acid or terephthalic acid or isophthalic acid.

Preferably, the polysiloxane has the formula:

wherein R1, R2, R3 and R4 are independently C1-C10 alkyl, cycloalkyl or aromatic groups and derivatives thereof.

Preferably, the polysiloxane has a number average molecular weight of 1000-.

Preferably, the polysiloxane accounts for 10 to 70 parts by weight, the lactam accounts for 30 to 90 parts by weight, the aminocaproic acid accounts for 0.5 to 1.5 parts by weight, and the catalyst accounts for 0.5 to 2.5 parts by weight.

Preferably, in the step S1, the temperature is raised to 190-230 ℃, and mechanical stirring is carried out for 1-2.5h under normal pressure.

Preferably, in the step S2, the temperature is raised to 240-260 ℃, the catalyst is added, the vacuum is pumped to 50-5000Pa, and the mechanical stirring is carried out for 1-3 h.

The invention has the beneficial effects that:

1. the reaction adopts the open loop of the aminocaproic acid, and can be carried out under normal pressure, so that the control is easy, the production cost is reduced, and the production efficiency is improved.

2. Because of the structural characteristics of the polysiloxane, the polysiloxane has a plurality of excellent and unique properties such as weather resistance, aging resistance, hydrophobicity, physiological inertia, high and low temperature resistance and the like, if the polysiloxane is used as a soft block to prepare a thermoplastic polylactam elastomer, the polysiloxane can endow the elastomer with the same excellent properties, and can be used as a compatilizer for blending nylon and silicone rubber.

Detailed Description

The invention is further illustrated by the following examples, but the scope of the invention as claimed is not limited to the scope of the examples.

Example 1

A preparation method of polyamide elastomer comprises the steps of adding 200g (1.77mol) of caprolactam, 4.24g (0.038mol) of aminocaproic acid and 14.6g (0.1mol) of adipic acid into a flask provided with a mechanical stirring, a thermometer and a reflux condenser, introducing nitrogen to the liquid level, keeping the temperature at 220 ℃, and stirring for 2 hours; adding 200g (0.1mol) of polysiloxane with molecular weight of 2000g/mol, heating to 250 ℃, adding 2.65g (0.009mol) of antimony trioxide, vacuumizing to 500Pa, stirring for 2.5h, extracting with boiling water after the reaction is finished, and drying to obtain the thermoplastic polyamide elastomer.

Example 2

A preparation method of polyamide elastomer comprises the steps of adding 170g (1.50mol) of caprolactam, 3.61g (0.028mol) of aminocaproic acid and 14.6g (0.1mol) of adipic acid into a flask provided with a mechanical stirring, a thermometer and a reflux condenser, introducing nitrogen to the liquid level, and stirring for 1.5 hours at the temperature of 220 ℃; adding 200g (0.1mol) of polysiloxane with molecular weight of 2000g/mol, heating to 250 ℃, adding 2.65g (0.009mol) of antimony trioxide, vacuumizing to 500Pa, stirring for 2h, extracting with boiling water after the reaction is finished, and drying to obtain the thermoplastic polyamide elastomer.

Example 3

A preparation method of polyamide elastomer comprises the steps of adding 150g (1.34mol) of caprolactam, 6.53g (0.050mol) of aminocaproic acid and 14.6g (0.1mol) of adipic acid into a flask provided with a mechanical stirring, a thermometer and a reflux condenser, introducing nitrogen to the liquid level, and stirring for 1.5 hours at the temperature of 220 ℃; adding 200g (0.1mol) of polysiloxane with molecular weight of 2000g/mol, heating to 240 ℃, adding 2.65g (0.009mol) of antimony trioxide, vacuumizing to 500Pa, stirring for 2.5h, extracting with boiling water after the reaction is finished, and drying to obtain the thermoplastic polyamide elastomer.

Comparative example 1

A preparation method of polyamide elastomer comprises the steps of adding 150g (1.34mol) of caprolactam, 3.21g (0.18mol) of water and 14.6g (0.1mol) of adipic acid into a 1L reaction kettle, introducing nitrogen to the liquid level, keeping the pressure below the liquid level at 0.5MPa, sealing the reaction kettle to prevent moisture from evaporating, and stirring at 220 ℃ for 1.5 hours; adding 200g (0.1mol) of polysiloxane with molecular weight of 2000g/mol, heating to 240 ℃, adding 2.65g (0.009mol) of antimony trioxide, vacuumizing to 500Pa, stirring for 2.5h, extracting with boiling water after the reaction is finished, and drying to obtain the thermoplastic polyamide elastomer.

Comparative example 2

A preparation method of polyamide elastomer comprises the steps of adding 150g (1.34mol) of caprolactam, 6.53g (0.050mol) of aminocaproic acid and 14.6g (0.1mol) of adipic acid into a flask provided with a mechanical stirring, a thermometer and a reflux condenser, introducing nitrogen to the liquid level, and stirring for 1.5 hours at the temperature of 220 ℃; adding 200g (0.1mol) of polyethylene glycol with molecular weight of 2000g/mol, heating to 240 ℃, adding 2.65g (0.009mol) of antimony trioxide, vacuumizing to 500Pa, stirring for 2.5h, extracting with boiling water after the reaction is finished, and drying to obtain the thermoplastic polyamide elastomer.

The compositions prepared in the examples were injection molded in standard sizes into test standard bars and the physical properties are given in Table 1.

TABLE 1

Physical Properties	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2
						Density (g/cm)3)	1.15	1.13	1.15	1.14	1.14
Tensile Strength (MPa)	52	49	48	50	51
						Elongation at Break (%)	>350	>400	>400	>400	>350
Melting Point (. degree.C.)	209	206	201	200	200
						Glass transition temperature (. degree. C.)	-49	-53	-59	-57	-43

As can be seen from Table 1, comparative example 1, which uses water as a ring-opener, although it can achieve effects similar to those of example 3, but the cost is significantly increased and the operation is inconvenient; comparative example 2, which uses polyethylene glycol as the soft segment, has a significantly smaller temperature range than example 3.

The foregoing detailed description is intended to illustrate and not limit the invention, which is intended to be within the spirit and scope of the appended claims, and any changes and modifications that fall within the true spirit and scope of the invention are intended to be covered by the following claims.