Toughened and modified PBT (polybutylene terephthalate) resin and preparation method thereof

Abstract

The invention relates to the technical field of PBT resin, and discloses toughened and modified PBT resin and a preparation method thereof.The PBT resin is prepared by taking PBT resin, a fiber modifier, an affinity agent and an antioxidant as raw materials through mixing, melt extrusion and granulation processes, illite fibers with the surfaces coated with rigid macromolecular substances of rigid pyrene rings are prepared to serve as the fiber modifier, and the toughening and modified PBT resin is prepared through melt extrusion and granulation. According to the present invention, the rigid macromolecular substance structure contains a large amount of carboxyl substituent groups, such that the rigid macromolecular substance can interact with the affinity agent during the subsequent melting process, and the molecular chain of the rigid macromolecular substance can produce the conjugation effect with the molecular chain of the PBT resin so as to improve the interface bonding property between the illite fiber and the PBT matrix, improve the toughness and the strength of the PBT resin, and improve the toughness and the strength of the illite fiber; by adding the affinity agent, on one hand, the compatibility between other additives and the PBT resin can be improved, and on the other hand, the toughness of the PBT resin can be further enhanced by utilizing the toughening modification effect of the butadiene styrene rubber.

Description

Technical Field

[0001] The invention relates to the technical field of PBT resins, and in particular to a toughened and modified PBT resin and a preparation method thereof. Background Art

[0002] Polybutylene terephthalate (PBT) is a polyester formed by the polycondensation of terephthalic acid and 1,4-butanediol. It is a milky white semi-transparent to opaque semi-crystalline thermoplastic and one of the five major engineering plastics. It has excellent rigidity, strength, heat resistance, good dimensional stability and chemical resistance. It has been widely used in important fields such as communications, point-of-sale, transportation, electrical engineering, aerospace, etc. Although PBT resin has many advantages, its poor strength and toughness have caused great obstacles to its application in some industries. For example, in the fields of automobile manufacturing and cable sheathing, the defects of insufficient strength and toughness can easily lead to the breakage of parts, which seriously affects the service life and safety of parts. Therefore, toughening and modification of PBT resin is of great significance for its further development.

[0003] At present, the main method for modifying PBT resin is to add toughening agents for blending modification, such as adding SEBS, EPDM or EVA, etc. However, the amount of toughening agents added needs to be strictly controlled, otherwise the strength of PBT resin may be reduced. In addition, by adding PC, PET, etc., the high crystallinity and rigidity of these polymer materials can also be used to enhance the PBT resin. In addition, inorganic fillers such as calcium carbonate and talcum powder can be added, and the high strength of inorganic fillers can be combined to achieve enhancement and modification of PBT resin. Therefore, the toughening and modification of PBT resin can be achieved by designing the components of PBT resin. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a toughened and modified PBT resin and a preparation method thereof.

[0006] (II) Technical solution

[0007] A method for preparing a toughened and modified PBT resin, wherein the PBT resin is prepared from the following raw materials measured in parts by weight: 65-75 parts of PBT resin, 3-4.5 parts of a fiber modifier, 5-15 parts of an affinity agent, and 0.5-1.5 parts of an antioxidant;

[0008] The preparation method comprises the following steps:

[0009] The first step is to weigh each raw material according to the weight and set aside;

[0010] Step 2: Add PBT resin, fiber modifier, affinity agent and antioxidant into the mixer, control the stirring speed to 1000-1200r / min, stir and mix at a temperature of 80-100°C to form a mixture;

[0011] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 250-270°C, the screw speed to 300-500rpm, and perform melt extrusion granulation to obtain PBT resin;

[0012] The fiber modifier is illite fiber with rigid macromolecular substances coated on the surface.

[0013] Preferably, the specific preparation method of the fiber modifier comprises the following steps:

[0014] Step 1: ultrasonically disperse illite fiber in toluene solvent to form a uniform dispersion, then add 2,3-dibromosuccinic acid and a phase transfer catalyst to the dispersion, stir evenly after the addition, then increase the temperature to 90-100°C, keep stirring for 3-6 hours, cool down and discharge, wash and vacuum dry to obtain functionalized illite fiber;

[0015] Step 2: Mix the functionalized illite fiber with N,N-dimethylformamide, add them to the polymerization kettle, ultrasonically disperse them evenly, introduce nitrogen protection, then add 2,3-dibromosuccinic acid and 2,7-dihydroxypyrene to the dispersion, and raise the temperature to 50-60°C. Under this temperature condition, add alkaline hydroxide solution to the polymerization kettle, and after the addition is completed, raise the temperature to 100-120°C, keep warm and stir for 12-24 hours, cool and discharge the material, separate the solid material, and the fiber modifier can be obtained.

[0016] Preferably, in step 1, the phase transfer catalyst is trifluoromethanesulfonic acid or p-toluenesulfonic acid.

[0017] Preferably, in step 2, the alkaline hydroxide is potassium hydroxide or sodium hydroxide.

[0018] Preferably, in step 2, the mass fraction of the alkaline hydroxide solution is 15-25%.

[0019] Preferably, in the step 2, the mass ratio of the functionalized illite fiber, 2,3-dibromosuccinic acid and 2,7-dihydroxypyrene is 1:0.5-0.6:0.8-1.

[0020] In the above technical scheme, a phase transfer catalyst is first used to catalyze the active carboxyl substituents in the structure of 2,3-dibromosuccinic acid to modify the surface of the illite fiber, thereby obtaining a hanging flower illite fiber containing a large number of halogen substituents on the surface. Then, 2,3-dibromosuccinic acid and 2,7-dihydroxypyrene are used as chain extension polymerization reagents. Under the catalysis of alkaline hydroxide, the halogen substituents and hydroxyl substituents in each other's structures can be in situ substituted and polymerized on the surface of the illite fiber to obtain an illite fiber of a rigid macromolecular substance coated with a rigid pyrene ring on the surface, i.e., a fiber modifier.

[0021] Preferably, the specific preparation method of the affinity agent is as follows:

[0022] Add styrene-butadiene rubber, diisopropylbenzene peroxide and functionalizing agent into the torque rheometer. After adding, control the temperature to 180-190°C, melt graft for 5-10 minutes at a rotation speed of 80-100rpm, then cool and discharge the material, pour it into xylene for precipitation, filter out the solid material, wash and vacuum dry it, and then obtain the affinity agent.

[0023] Preferably, the functionalizing agent is any one of isocyanoethyl methacrylate, isocyanate ethyl acrylate or 3-isopropyl-dimethylbenzyl isocyanate.

[0024] In the above technical scheme, dicumyl peroxide is used as an initiator to initiate graft polymerization of styrene-butadiene rubber and a functionalizing agent under high temperature melting conditions to obtain styrene-butadiene rubber containing isocyanate functional groups in its structure, namely, an affinity agent.

[0025] Preferably, the antioxidant is any one of a hindered phenol antioxidant or a phosphite antioxidant.

[0026] A toughened and modified PBT resin is prepared by adopting the above preparation method.

[0027] (III) Beneficial technical effects

[0028] (1) The present invention prepares illite fiber with a rigid macromolecular substance coated with a rigid pyrene ring on the surface as a fiber modifier. First, since the rigid macromolecular substance contains a large number of carboxyl substituents in its structure, it can interact with the isocyanate groups in the affinity agent structure during the subsequent melting process. Moreover, due to the presence of a large number of rigid pyrene rings, the molecular chains of the rigid macromolecular substance can produce a conjugated effect with the molecular chains of the PBT resin. These interaction forces can improve the interface bonding between the illite fiber and the PBT matrix, so that the illite fiber can effectively exert its own effect of dispersing stress and transferring load, thereby improving the toughness and strength of the PBT resin.

[0029] (2) The present invention prepares styrene-butadiene rubber containing highly active isocyanate groups in its structure as an affinity agent, which can improve the compatibility between other additives and PBT resin on the one hand, and can also utilize the toughening modification effect of styrene-butadiene rubber to further enhance the toughness of PBT resin on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0031] Figure 1 These are scanning electron microscope images of illite fiber and fiber modifier, where (A) is a scanning electron microscope image of illite fiber, and (B) is a scanning electron microscope image of the fiber modifier. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0033] Preparation Example 1

[0034] Preparation of fiber modifier:

[0035] Step 1: ultrasonically disperse 1.5 g of illite fiber in toluene solvent to form a uniform dispersion, then add 2.5 g of 2,3-dibromosuccinic acid and 0.1 g of p-toluenesulfonic acid to the dispersion, stir evenly after the addition, then raise the temperature to 100° C., keep stirring for 4 hours, cool down and discharge, wash and vacuum dry to obtain functionalized illite fiber;

[0036] Step 2: Mix 0.8 g of functionalized illite fiber with N,N-dimethylformamide, add them to the polymerization kettle, ultrasonically disperse them evenly, introduce nitrogen protection, then add 0.4 g of 2,3-dibromosuccinic acid and 0.8 g of 2,7-dihydroxypyrene to the dispersion, and raise the temperature to 60°C. Under this temperature condition, add 10 mL of 20% potassium hydroxide solution to the polymerization kettle. After the addition is completed, raise the temperature to 120°C, keep warm and stir for 24 hours, cool and discharge the material, separate the solid material, and the fiber modifier can be obtained.

[0037] Figure 1The figures are scanning electron microscope images of illite fiber and fiber modifier, where (A) is the scanning electron microscope image of illite fiber and (B) is the scanning electron microscope image of fiber modifier. It can be observed that the surface of illite fiber is smooth and flat without obvious special morphology, while the surface of fiber modifier presents a special uneven morphology. Analysis shows that this special morphology is caused by the modification of rigid macromolecular substances.

[0038] Preparation Example 2

[0039] Preparation of affinity agent:

[0040] 10g of styrene-butadiene rubber, 0.1g of diisopropylbenzene peroxide and 0.8g of isocyanoethyl methacrylate were added into the torque rheometer. After the addition, the temperature was controlled to 180°C, and melt grafting was carried out at a rotation speed of 80rpm for 5 minutes. Then the temperature was lowered and the material was discharged. The material was poured into xylene for precipitation, and the solid material was filtered out. After washing and vacuum drying, the affinity agent was obtained.

[0041] Example 1

[0042] A toughened and modified PBT resin is prepared by using the following raw materials measured in parts by weight: 65 parts of PBT resin, 3 parts of fiber modifier, 5 parts of affinity agent, and 0.5 parts of phosphite;

[0043] The preparation method comprises the following steps:

[0044] The first step is to weigh each raw material according to the weight and set aside;

[0045] Step 2: Add PBT resin, fiber modifier, affinity agent and phosphite into a mixer, control the stirring rate to 1000r / min, stir and mix at a temperature of 80°C to form a mixture;

[0046] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 250°C, and the screw speed to 300rpm, and perform melt extrusion granulation to obtain PBT resin.

[0047] The preparation method of the fiber modifier is shown in Preparation Example 1; the preparation method of the affinity agent is shown in Preparation Example 2, and the same applies to the following.

[0048] Example 2

[0049] A toughened and modified PBT resin is prepared by using the following raw materials measured by weight: 68 parts of PBT resin, 4 parts of fiber modifier, 12 parts of affinity agent, and 0.6 parts of phosphite;

[0050] The preparation method comprises the following steps:

[0051] The first step is to weigh each raw material according to the weight and set aside;

[0052] Step 2: Add PBT resin, fiber modifier, affinity agent and phosphite into a mixer, control the stirring rate to 1200r / min, stir and mix at a temperature of 100°C to form a mixture;

[0053] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 260°C and the screw speed to 400rpm, and perform melt extrusion granulation to obtain PBT resin.

[0054] Example 3

[0055] A toughened and modified PBT resin is prepared by using the following raw materials measured by weight: 75 parts of PBT resin, 4.5 parts of fiber modifier, 15 parts of affinity agent, and 1.5 parts of phosphite;

[0056] The preparation method comprises the following steps:

[0057] The first step is to weigh each raw material according to the weight and set aside;

[0058] Step 2: Add PBT resin, fiber modifier, affinity agent and phosphite into a mixer, control the stirring rate to 1200r / min, stir and mix at a temperature of 100°C to form a mixture;

[0059] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 270°C, and the screw speed to 500rpm, and perform melt extrusion granulation to obtain PBT resin.

[0060] Comparative Example 1

[0061] A toughened and modified PBT resin is prepared by using the following raw materials measured by weight: 68 parts of PBT resin, 4 parts of illite fiber, 12 parts of affinity agent, and 0.6 parts of phosphite;

[0062] The preparation method comprises the following steps:

[0063] The first step is to weigh each raw material according to the weight and set aside;

[0064] Step 2: Add PBT resin, illite fiber, affinity agent and phosphite into a mixer, control the stirring rate to 1200r / min, stir and mix at a temperature of 100°C to form a mixture;

[0065] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 260°C and the screw speed to 400rpm, and perform melt extrusion granulation to obtain PBT resin.

[0066] Comparative Example 2

[0067] A toughened and modified PBT resin is prepared by using the following raw materials measured in parts by weight: 68 parts of PBT resin, 12 parts of affinity agent, and 0.6 parts of phosphite;

[0068] The preparation method comprises the following steps:

[0069] The first step is to weigh each raw material according to the weight and set aside;

[0070] Step 2: Add PBT resin, affinity agent and phosphite into a mixer, control the stirring rate to 1200r / min, stir and mix at a temperature of 100°C to form a mixture;

[0071] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 260°C and the screw speed to 400rpm, and perform melt extrusion granulation to obtain PBT resin.

[0072] Comparative Example 3

[0073] A toughened and modified PBT resin is prepared by using the following raw materials measured by weight: 68 parts of PBT resin, 4 parts of fiber modifier, 12 parts of styrene-butadiene rubber, and 0.6 parts of phosphite;

[0074] The preparation method comprises the following steps:

[0075] The first step is to weigh each raw material according to the weight and set aside;

[0076] Step 2: Add PBT resin, fiber modifier, styrene-butadiene rubber and phosphite into a mixer, control the stirring rate to 1200 r / min, stir and mix at a temperature of 100° C. to form a mixture;

[0077] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 260°C and the screw speed to 400rpm, and perform melt extrusion granulation to obtain PBT resin.

[0078] Comparative Example 4

[0079] A toughened and modified PBT resin is prepared by using the following raw materials measured by weight: 68 parts of PBT resin, 4 parts of fiber modifier, and 0.6 parts of phosphite;

[0080] The preparation method comprises the following steps:

[0081] The first step is to weigh each raw material according to the weight and set aside;

[0082] Step 2: Add PBT resin, fiber modifier and phosphite into a mixer, control the stirring rate to 1200r / min, stir and mix at a temperature of 100°C to form a mixture;

[0083] The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 260°C and the screw speed to 400rpm, and perform melt extrusion granulation to obtain PBT resin.

[0084] Test Case

[0085] The PBT resins in the examples and comparative examples were made into test specimens and subjected to comprehensive performance tests. The results are recorded in Table 1:

[0086] Table 1 - Performance test results

[0087]

[0088] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a toughened and modified PBT resin, characterized in that: The PBT resin is made of the following raw materials measured by weight: 65-75 parts of PBT resin, 3-4.5 parts of fiber modifier, 5-15 parts of affinity agent, and 0.5-1.5 parts of antioxidant; The preparation method comprises the following steps: The first step is to weigh each raw material according to the weight and set aside; Step 2: Add PBT resin, fiber modifier, affinity agent and antioxidant into the mixer, control the stirring speed to 1000-1200r / min, stir and mix at a temperature of 80-100°C to form a mixture; The third step is to feed the mixed material into a twin-screw extruder, control the screw temperature to 250-270°C, the screw speed to 300-500rpm, and perform melt extrusion granulation to obtain PBT resin; The fiber modifier is illite fiber with rigid macromolecular substances coated on the surface.

2. The method for preparing a toughened and modified PBT resin according to claim 1, characterized in that: The specific preparation method of the fiber modifier comprises the following steps: Step 1: ultrasonically disperse illite fiber in toluene solvent to form a uniform dispersion, then add 2,3-dibromosuccinic acid and a phase transfer catalyst to the dispersion, stir evenly after the addition, then increase the temperature to 90-100°C, keep stirring for 3-6 hours, cool down and discharge, wash and vacuum dry to obtain functionalized illite fiber; Step 2: Mix the functionalized illite fiber with N,N-dimethylformamide, add them to the polymerization kettle, ultrasonically disperse them evenly, introduce nitrogen protection, then add 2,3-dibromosuccinic acid and 2,7-dihydroxypyrene to the dispersion, and raise the temperature to 50-60°C. Under this temperature condition, add alkaline hydroxide solution to the polymerization kettle, and after the addition is completed, raise the temperature to 100-120°C, keep warm and stir for 12-24 hours, cool and discharge the material, separate the solid material, and the fiber modifier can be obtained.

3. The method for preparing a toughened and modified PBT resin according to claim 2, characterized in that: In the step 1, the phase transfer catalyst is trifluoromethanesulfonic acid or p-toluenesulfonic acid.

4. The method for preparing a toughened and modified PBT resin according to claim 2, characterized in that: In the step 2, the alkaline hydroxide is potassium hydroxide or sodium hydroxide.

5. The method for preparing a toughened and modified PBT resin according to claim 2, characterized in that: In the step 2, the mass fraction of the alkaline hydroxide solution is 15-25%.

6. The method for preparing a toughened and modified PBT resin according to claim 2, characterized in that: In the step 2, the mass ratio of the functionalized illite fiber, 2,3-dibromosuccinic acid and 2,7-dihydroxypyrene is 1:0.5-0.6:0.8-1.

7. The method for preparing a toughened and modified PBT resin according to claim 1, characterized in that: The specific preparation method of the affinity agent is as follows: Add styrene-butadiene rubber, diisopropylbenzene peroxide and functionalizing agent into the torque rheometer. After adding, control the temperature to 180-190°C, melt graft for 5-10 minutes at a rotation speed of 80-100rpm, then cool and discharge the material, pour it into xylene for precipitation, filter out the solid material, wash and vacuum dry it, and then obtain the affinity agent.

8. The method for preparing a toughened and modified PBT resin according to claim 7, characterized in that: The functionalizing agent is any one of isocyanoethyl methacrylate, isocyanate ethyl acrylate or 3-isopropyl-dimethylbenzyl isocyanate.

9. The method for preparing a toughened and modified PBT resin according to claim 1, characterized in that: The antioxidant is any one of a hindered phenol antioxidant or a phosphite antioxidant.

10. A toughened and modified PBT resin, characterized in that: The method is prepared according to any one of claims 1 to 9.

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