CN110684288B

CN110684288B - Preparation method and application of special aid for improving polybutene-1 crystal form conversion rate

Info

Publication number: CN110684288B
Application number: CN201911092720.4A
Authority: CN
Inventors: 王波; 李旺; 林福华; 杨彰雄; 刘焱超; 韩晓静; 李静博
Original assignee: Taiyuan University of Science and Technology
Current assignee: Taiyuan University of Science and Technology
Priority date: 2019-11-11
Filing date: 2019-11-11
Publication date: 2021-12-10
Anticipated expiration: 2039-11-11
Also published as: CN110684288A

Abstract

The invention relates to a preparation method of a special auxiliary agent for improving the conversion rate of a polybutene-1 crystal form and application of the special auxiliary agent, belonging to the technical field of high polymer materials, and specifically comprising the steps of dissolving white solid powder of norbornene dicarboxylic acid soap metal salt in N, N-dimethylformamide and completely dissolving the white solid powder; slowly dripping hydrochloric acid solution, and adjusting the pH value to 2-5; adding cellulose powder into the system, and stirring to uniformly disperse the cellulose powder; then adding dropwise sodium hydroxide solution, adjusting the pH value to 8-10, maintaining the temperature at 80-100 ℃, and stirring for reaction for 2-6 hours; after the reaction is finished, filtering, washing and drying the solid product, then placing the solid product in N, N-dimethylformamide to remove impurities, and finally filtering, washing and drying the solid product to obtain white powder, wherein the white powder is a special aid, and the special aid prepared by the invention can shorten the time for converting PB-1 into a stable crystal form I after melt processing to about 36h, so that the PB-1 can be produced and applied in a large scale.

Description

Preparation method and application of special aid for improving polybutene-1 crystal form conversion rate

Technical Field

The invention relates to a preparation method of a special auxiliary agent for improving the crystal form conversion rate of polybutene-1 and application of the special auxiliary agent, and belongs to the technical field of high polymer materials.

Background

The polybutene-1 (PB-1) has excellent comprehensive performance and is especially suitable for hot water pipes in drinking, heating and other fields. Compared with the current domestic mainstream random copolymerization polypropylene (PP-R) pipe, the PB-1 pipe has the advantages of strong hoop stress bearing capacity, excellent creep resistance, low energy consumption, no scaling and the like after long-term use, and the construction performance is similar to that of PP-R. However, PB-1 is a polycrystalline polymer, firstly generates an unstable crystal form II after melt processing and molding, and can be converted into a stable and valuable crystal form I after 7 days at room temperature. The above disadvantages limit the wide application of iPB, which is a problem to be solved.

In recent years, researchers have made progress to accelerating the crystal transformation rate by using methods such as mixing auxiliary forming, memory ordered melting, two-step annealing and the like. However, the above methods have disadvantages that the operation is complicated and the industrial application is impossible.

Chinese patents with publication numbers CN106046573A, CN106147045A, CN105924811A and CN106147044A all report a series of applications of directly using polypropylene nucleating agent to promote the conversion rate of PB-1 crystal form. However, PB-1 in the above study was completely converted in about 44 hours, and the completion of conversion in 44 hours was far from the practical requirement.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a preparation method of a special auxiliary agent for improving the conversion rate of a polybutene-1 crystal form and an application of the special auxiliary agent, and by adding the special auxiliary agent, the time for converting PB-1 into a stable crystal form I after melt processing can be shortened to about 36h, so that the special auxiliary agent is suitable for large-scale production and application of PB-1.

In order to achieve the purpose, the technical scheme adopted by the invention is a preparation method of a special auxiliary agent for improving the crystal form conversion rate of polybutene-1, and the preparation method comprises the following steps:

s1, dissolving 5g of norbornene dicarboxylic acid soap metal salt white solid powder in 50-100ml of N, N-dimethylformamide at the temperature of 100-130 ℃ to completely dissolve the powder;

s2, slowly dripping hydrochloric acid solution with excessive concentration of 30-50% into the system in the step S1 to keep the pH value of the system between 2-5;

s3, adding 1-5g of cellulose powder with the grain diameter of 20-200 mu m into the system in the step S2, and stirring to uniformly disperse the cellulose powder;

s4, adding dropwise sodium hydroxide solution with the concentration of 30% -50% into the system in the step S3 to maintain the pH value of the system between 8 and 10, maintain the temperature of the system between 80 ℃ and 100 ℃, and stirring and reacting for 2-6 hours;

s5, after the reaction is finished, filtering, washing and drying the solid product, then placing the dried powder in 50-100ml of N, N-dimethylformamide at 130 ℃ for impurity removal, and finally filtering, washing and drying to obtain white powder, wherein the white powder is a special auxiliary agent capable of greatly improving the crystal form conversion rate of the polybutene-1.

Preferably, the structural formula of the norbornene dicarboxylic acid soap metal salt in the step S1 is

Wherein, when M is a metal element with a valence of 2-3, and M is a metal element with a valence of 3, x ═ y ═ 1; when M is a metal element with a valence of 2, x is 1, and y is 2.

Preferably, the cellulose powder in step S3 is microcrystalline cellulose or bacterial cellulose.

The application of the special auxiliary agent for improving the crystal form conversion rate of the polybutene-1 is to uniformly mix polybutene-1 resin and 0.01 to 0.5 percent of the special auxiliary agent in a high-speed mixer, and to form the polybutene-1 crystal form by the steps of extrusion, granulation, injection molding and the like.

Preferably, the usage amount of the special auxiliary agent is 0.1%.

Compared with the prior art, the invention has the following technical effects.

1. The method has the advantages of simple operation method and simple reaction principle, and can be used for large-scale production. The norbornene dicarboxylic acid soap molecular chain is combined with the cellulose through chemical reaction by a simple method, rather than simple mixing, so that the effect of the special auxiliary agent is greatly improved.

2. During the melting process, the cellulose induces polybutene-1 to accelerate the crystal form transformation rate through heterogeneous nucleation. In addition, norbornene dicarboxylic acid soap molecules are recrystallized on the surface of cellulose to form crystals with more perfect micro-morphology, so that the conversion rate of the polybutene-1 crystal form is further accelerated.

3. Through chemical reaction, hydroxyl on a cellulose molecular chain is greatly reduced, so that the special auxiliary agent can be better dispersed in a polybutene-1 matrix, and a more excellent effect is achieved.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The starting materials, reagents and equipment used in the present invention are those conventionally commercially available in the art unless otherwise specified. Wherein PB-1 is purchased from Mitsui chemical company of Japan and has a melt index of 50-200g/10 min.

The effect of the present invention on the crystalline form conversion of polybutene-1 is further illustrated by comparing the specific examples of the present invention with comparative examples 1 and 2.

Example 1

5g of norbornene dicarboxylic acid aluminum soap salt white solid powder was dissolved in 100ml of N, N-dimethylformamide at 130 ℃. After complete dissolution, a 30% excess hydrochloric acid solution was slowly added dropwise to the mixture at room temperature, maintaining the pH of the reaction at 3. 1g of bacterial cellulose powder having a particle size of 20 μm was added to the above reaction mixture, and stirred to disperse the powder uniformly. Then, a 50% sodium hydroxide solution was added dropwise to the reaction mixture to maintain the pH of the system at 8. The reaction temperature was maintained at 80 ℃ and the reaction was stirred for 4 hours. And after the reaction is finished, filtering, washing and drying the solid product. Then the dried powder is placed in 100ml of N, N-dimethylformamide at 130 ℃ for impurity removal. And finally, filtering, washing and drying to obtain the special auxiliary white powder capable of greatly improving the PB-1 crystal form conversion rate.

0.1g of the special auxiliary agent and 1000g of PB-1 are uniformly mixed in a high-speed mixer and are molded through the steps of extrusion, granulation, injection molding and the like.

10mg of the above sample was placed in an aluminum crucible and placed in a Differential Scanning Calorimeter (DSC). DSC was set up as follows: increasing the temperature from 20 ℃ to 200 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 5min, decreasing the temperature from 200 ℃ to 20 ℃ at a cooling rate of 60 ℃/min, and finally increasing the temperature from 20 ℃ to 200 ℃. And recording the last temperature rise curve, and obtaining the melting enthalpy delta H1 of the crystal form I and the melting enthalpy delta H2 of the crystal form II of the PB-1 from the last temperature rise curve. The crystal form conversion (T) of PB-1 was determined by the following equation.

The samples were tested and the crystal form conversion was calculated every 12h from 0 h after molding, according to the method described above. Specific data are shown in table 1.

Comparative example 1

0.1g of norbornene dicarboxylic acid soap aluminum salt solid powder described in example 1 and 1000g of PB-1 were uniformly mixed in a high-speed mixer, and subjected to extrusion, granulation, injection molding and the like to mold. The samples were tested and the crystal form conversion was calculated every 12h from 0 h after molding, according to the method described above. Specific data are shown in table 1.

Comparative example 2

1000g of PB-1 is uniformly mixed in a high-speed mixer and is molded through the steps of extrusion, granulation, injection molding and the like. The samples were tested and the crystal form conversion was calculated every 12h from 0 h after molding, according to the method described above. Specific data are shown in table 1.

TABLE 1 conversion of the forms of PB-1 described in the examples and comparative examples

As can be seen from Table 1, the PB-1 material added with the special auxiliary synthesized by the invention completes the conversion from the crystal form II to the crystal form I within 36 hours after the forming. In contrast, the material of comparative example 1 was accelerated by 12 hours at 48 hours. And pure PB-1 only completes 75.89% of crystal form conversion after being placed for 48 hours, which shows that the special auxiliary synthesized by the invention has obvious effect on improving the PB-1 crystal form conversion rate and can shorten the processing period, thereby having important significance on the application of PB-1.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principles of the present invention are intended to be included therein.

Claims

1. A preparation method of a special auxiliary agent for improving the conversion rate of a polybutene-1 crystal form is characterized by comprising the following steps:

s1, dissolving 5g of norbornene dicarboxylic acid soap aluminum salt white solid powder in 50-100ml of N, N-dimethylformamide at the temperature of 100-130 ℃ to completely dissolve the powder;

s4, then dropwise adding a sodium hydroxide solution with the concentration of 30-50% into the system in the step S3 to maintain the pH value of the system between 8 and 10, maintain the temperature of the system between 80 and 100 ℃, and stirring and reacting for 2 to 6 hours;

2. The preparation method of the special additive for improving the conversion rate of the crystal form of polybutene-1 according to claim 1, wherein: the structural formula of the norbornene dicarboxylic acid soap aluminum salt in the step S1 is

。

3. The preparation method of the special additive for improving the conversion rate of the crystal form of polybutene-1 according to claim 1, wherein: the cellulose powder in the step S3 is microcrystalline cellulose or bacterial cellulose.

4. The application of the special auxiliary agent prepared by the preparation method for improving the crystal form conversion rate of polybutene-1 according to claim 1 or 2, wherein the special auxiliary agent is prepared by the following steps: the polybutene-1 resin and 0.01-0.5% of the special assistant are mixed in a high-speed mixer uniformly and are molded through the steps of extrusion, granulation and injection molding.

5. The application of the special additive for improving the conversion rate of the polybutene-1 crystal form according to claim 4, wherein: the usage amount of the special auxiliary agent is 0.1%.