Polyphenylene sulfide oligomer long-chain branching modification method

Abstract

The invention relates to the field of high polymer materials, and particularly provides a polyphenylene sulfide oligomer long-chain branching modification method, two chain extenders, namely a chain extender A and a chain extender B, are added, the chain extender A can increase the molecular chain length of polyphenylene sulfide, and the chain extender B increases the branching degree of the molecular chain while increasing the molecular weight length, so that the polyphenylene sulfide oligomer long-chain branching modification effect is improved. The molar mass of the polyphenylene sulfide oligomer is increased under the combined action of the two, the toughness of the polyphenylene sulfide is improved while the melt viscosity is improved, and in addition, the toughness of the material is further improved while the cost is reduced by adding nano calcium carbonate. Compared with thermal oxidation crosslinking, the preparation method has the advantages of short treatment time and high production efficiency, and compared with other blending modification, the preparation method has the advantages that high-molecular-weight polyphenylene sulfide does not need to be added, and the mixing process is simple.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a method for modifying long-chain branches of polyphenylene sulfide oligomers. Background Art

[0002] At present, the oligomer products in the production process of domestic polyphenylene sulfide industry have a narrow application range due to low melt viscosity, poor tensile and impact toughness. Most of them are disposed by landfill, incineration, dilution and discharge into the sea together with waste salt, resulting in a large waste of resources and environmental pollution. The commonly used improvement method is to obtain cross-linked polymers by thermal oxygen cross-linking, but the processing time required for thermal oxygen cross-linking of resins is relatively long, which greatly affects the production efficiency of cross-linked products, especially when the target melt index MFR is high.

[0003] Another method is to blend polyphenylene sulfide oligomers with polymers such as fiber-grade polyphenylene sulfide to increase the molecular weight of polyphenylene sulfide under the action of a coupling agent. However, this method generally requires the use of a larger amount of polymer polyphenylene sulfide, generally more than 50%, and the mixing process is complicated, which seriously affects the production efficiency of the product.

[0004] CN116178955A discloses a method for cross-linking and modifying polyphenylene sulfide oligomers, which requires mixing polyphenylene sulfide oligomers and fiber-grade polyphenylene sulfide with a higher degree of polymerization for 25-35 minutes, and then mixing with a chain extender for a second time for 25-35 minutes. After the second mixing, it is necessary to mix with a coupling agent for a third time, and then extrude and granulate the mixture obtained by the third mixing to obtain a finished product. The mixing process is complicated and the operation is cumbersome, and fiber-grade polyphenylene sulfide with a higher degree of polymerization needs to be used, which has high requirements for raw materials.

[0005] Therefore, there is an urgent need to develop a method for processing polyphenylene sulfide oligomers that is time-saving, efficient, has a simple mixing process, and does not require the use of a large amount of polyphenylene sulfide polymers. Summary of the invention

[0006] In order to solve the problems existing in the prior art that polyphenylene sulfide oligomers have low molecular weight, low viscosity, poor tensile and impact toughness, and that the existing processing methods of polyphenylene sulfide oligomers are time-consuming, inefficient, and have a complicated mixing process and require the use of more polyphenylene sulfide polymers, the present invention provides a long-chain branching modification method for polyphenylene sulfide oligomers. Compared with thermal oxidative crosslinking, the method has the advantages of short processing time and high production efficiency. Compared with other blending modifications, there is no need to add high molecular weight polyphenylene sulfide, and the mixing process is simple.

[0007] The method adopts a twin-screw extruder and adds two chain extenders, chain extender A and chain extender B, wherein the chain extender A can increase the molecular chain length of polyphenylene sulfide, and the chain extender B increases the branching degree of the molecular chain while increasing the molecular weight length. Under the joint action of the two, the molar mass of the polyphenylene sulfide oligomer is increased, the melt viscosity is increased, and the toughness of the polyphenylene sulfide is increased. In addition, by adding nano calcium carbonate, the toughness of the material is further increased while the cost is reduced.

[0008] The present invention provides a long-chain branching modification method for polyphenylene sulfide oligomers, comprising the following steps:

[0009] 1) washing and drying the polyphenylene sulfide oligomer;

[0010] 2) mixing the polyphenylene sulfide oligomer washed and dried in step 1) with chain extender A and chain extender B;

[0011] 3) extruding the mixture obtained in step 2); extrusion granulation uses two sets of side feeds, the mixture enters the screw through side feed 1, and the nano calcium carbonate enters the screw through side feed 2, the mass ratio is controlled by a loss-in-weight scale on the side feed, and extrusion granulation is performed;

[0012] 4) After granulation, the pellets are dried.

[0013] The chain extender A is ethylene maleic anhydride syndiotactic copolymer resin (ZeMac), and its molecular structure is as follows:

[0014]

[0015] Preferably, n in the above ZeMac molecular structure formula is 70-80.

[0016] The chain extender B is triglycidyl isocyanurate (TGIC), and its molecular structure is as follows:

[0017]

[0018] Preferably, in step 1), the number average molecular weight Mn of the polyphenylene sulfide oligomer is 15000-20000, and the washing and drying are specifically washing the polyphenylene sulfide oligomer in pure water at 75-95° C. with stirring for 1-2 hours, filtering, and then drying in an oven at 100-130° C. for 3-6 hours;

[0019] Preferably, in step 2), the polyphenylene sulfide oligomer is mixed with the chain extender A and the chain extender B in a weight ratio of 100:(0.5-1.5):(0.5-1.5).

[0020] If the amount of chain extender A and chain extender B is lower than this range, the modification effect will not be obvious. If it is higher than this range, the polymer material will be over-crosslinked, making the material brittle and easy to crack and break. This will significantly reduce the physical properties of the polymer.

[0021] Preferably, in step 2), the mixing speed is 100-200 r / min, and the mixing time is 10-30 min. If the mixing time is shorter than this, the polyphenylene sulfide and the chain extender are not mixed evenly.

[0022] Preferably, the process parameters adopted by the screw in step 3) are that the temperature of the extrusion granulation is set to 310-315°C in zone 1, 315-325°C in zone 2, 310-325°C in zone 3, 310-315°C in zone 4, and 300-320°C in zone 5, and the head temperature is set to 290-330°C.

[0023] The mass ratio of the nano-calcium carbonate used in step 3) to the polyphenylene sulfide oligomer in step 1) is (8-12):100, the average particle size of the nano-calcium carbonate is 50-80nm, and the purity is 95%-99%.

[0024] Preferably, in step 4), after granulation, the pellets are dried in an oven at 100-130° C. for 3-6 hours to obtain pellets.

[0025] The product treated by the above method has a higher molecular weight, a lower melt index, and better toughness, while reducing the cost of raw materials, thereby expanding the application channels and scope of polyphenylene sulfide. Therefore, this application also claims to protect the polyphenylene sulfide product obtained by the above modification method.

[0026] The present invention adopts twin-screw extruder equipment and uses two chain extenders, chain extender A and chain extender B, wherein the chain extender A can increase the molecular chain length of polyphenylene sulfide, and the chain extender B increases the branching degree of the molecular chain while increasing the molecular weight length. Under the joint action of the two, the molecular weight is increased, the melt viscosity is increased, and the toughness of the polyphenylene sulfide is improved. In addition, by adding nano calcium carbonate filling, the toughness of the material is further increased while the cost is reduced.

[0027] The key point of the present invention is to use two chain extenders, one of which is to increase the length of the molecular chain. This increase usually leads to an increase in the viscosity of the material under the same conditions, because long-chain molecules require more energy to overcome the interaction force between segments during the flow process. In terms of toughness, when subjected to external forces, long-chain molecules can absorb and disperse energy through the stretching and curling of the segments, thereby delaying the expansion of cracks and the occurrence of fractures. The other is mainly to increase the degree of branching of the molecular chain. The effect of branching on viscoelasticity depends on the length and number of the branch chain. For short branch chains, their presence can reduce the entanglement between molecular chains, increase the distance between molecules, and thus reduce viscosity. However, when the length of the branch chains increases to a certain extent, they may form their own entangled structure, resulting in an increase in viscosity. In addition, moderate branching can increase the flexibility and energy absorption capacity of the molecular chain and improve the toughness of the material.

[0028] Therefore, this patent adopts two chain extenders in combination. If only chain extender B is added, short chain branches will be formed, which is not conducive to improving the viscosity of the melt. Therefore, chain extender A is added to increase the molecular chain length. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the reaction process of the present invention;

[0030] Figure 2 It is a schematic diagram of the feeding position of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with specific embodiments. These embodiments are only used to illustrate the technical solution of the present invention in more detail and should not be construed as limiting the protection scope of the present invention.

[0032] The polyphenylene sulfide oligomers used in the following examples and comparative examples are polyphenylene sulfide oligomers from the same production batch with a molecular weight of 15,000-20,000.

[0033] Nano calcium carbonate was purchased from Zhejiang Manli Nanotechnology Co., Ltd. with an average particle size of 50 nm and a purity of 99%.

[0034] The ZeMac used was ZeMac E400, purchased from Shanghai NanoSu Alloy Technology Co., Ltd., and its molecular weight was 10,000.

[0035] The raw material proportions (by weight) of Examples 1-4 and Comparative Examples 1-6 are shown in Table 1.

[0036] Table 1 Raw material ratios of Examples 1-4 and Comparative Examples 1-6

[0037]

[0038] The above-mentioned embodiment and comparative example are processed according to the same process and parameters, and the reaction process is as follows: Figure 1 As shown, the specific steps are as follows:

[0039] 1) stirring and washing the aforementioned polyphenylene sulfide oligomer in pure water at 90° C. for 1 hour, and drying in an oven at 110° C. for 4 hours;

[0040] 2) mixing the washed and dried polyphenylene sulfide oligomer with ZeMac and TGIC in the ratio shown in Table 1, with a mixing time of 10 min and a mixing speed of 150 r / min to obtain a mixture;

[0041] 3) Extruding the mixture obtained in step 2); extrusion granulation using two sets of side feeds, such as Figure 2 As shown, the mixture enters the screw through side feed 1, and nano calcium carbonate enters the screw through side feed 2. The mass ratio is controlled by a loss-in-weight scale on the side feed, and extrusion granulation is performed. The amount of nano calcium carbonate added is shown in Table 1, and the particle size of the nano calcium carbonate is 50 nm and the purity is 99%.

[0042] Figure 2 It is a schematic diagram of feeding, wherein the side feed 1 is arranged in the first zone of the screw, and the side feed 2 is arranged in the fourth zone of the screw.

[0043] The temperatures of the screw are 310°C in zone 1, 315°C in zone 2, 325°C in zone 3, 315°C in zone 4, and 300°C in zone 5, and the die head temperature is set to 300°C;

[0044] 4) After granulation, the pellets were dried in an oven at 110°C for 4 h.

[0045] Examples 5-8 use the same material ratio as Example 2, and the overall preparation method is the same as the preparation method of the above Examples 1-4 and Comparative Examples 1-6, but the process parameters are changed. The process parameters of Examples 5-8 are shown in Table 2.

[0046] Table 2 Process parameters of Examples 5-8

[0047]

[0048] The pellets of Examples 1-4 and Comparative Examples 1-6 were tested, and the test results are shown in Table 3.

[0049] Table 3 Performance index test results of the products treated with Examples 1-4 and Comparative Examples 1-6

[0050]

[0051]

[0052] It can be seen from the data that the addition of nano-calcium carbonate reduces the MFR of PPS from 613 in comparative example 1 to 530g / 10min in comparative example 2, with a decrease of 13.5%; the crystallization temperature increases from 185 to 192°C; the mechanical properties are improved to varying degrees, among which the tensile strength and notched impact strength are the most significant, increasing by 23% and 18% respectively, indicating that the addition of nano-calcium carbonate improves the strength, toughness and melt viscosity of the material.

[0053] Nano calcium carbonate is spherical and has a higher specific surface area, which is conducive to the full contact and impregnation of polyphenylene sulfide and calcium carbonate, improving their integrity and thus having better mechanical properties.

[0054] The addition of ZeMac and TGIC in different proportions improved the material properties to varying degrees. When the addition amount reached 1.5 parts, the effect of improving the material properties decreased. Example 1-4 is a composite addition of ZeMac and TGIC. Compared with the addition of either alone, the viscosity, molecular weight and mechanical properties of the material are more significantly improved. When the addition amount of ZeMac is 1 part and TGIC is 0.5 parts, the effect is best. When the content exceeds this, the toughness decreases rapidly due to excessive crosslinking and the impact performance decreases.

[0055] It can be seen from Examples 2-4 that when a certain amount of chain extender is added, further increasing the amount of addition will lead to a decrease in impact performance. The reason is that over-crosslinking occurs, which reduces the number of freely rotatable segments and reduces the flexibility of the material.

[0056] It can be seen from Comparative Examples 3-6 that when chain extender A or chain extender B is added alone, the viscosity is significantly reduced compared with the examples. The main reason is that when chain extender A ZeMac is added alone, although the length of the polymer chain can be increased, the molecular weight and viscosity cannot be increased by forming branches. When chain extender B TGIC is added alone, branches can be formed on the polymer chain, but since short branches are formed, the short branches reduce the entanglement between molecules and increase the distance between molecules, which is not conducive to the increase of viscosity.

[0057] The above-mentioned performance test was carried out on the products obtained in Examples 5-8, and the results showed that their performance was not much different from that of Example 2, indicating that they all had good effects within the process parameters specified in this application.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions, modifications, etc. made by technicians in this field without any creative work within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for modifying long-chain branching of polyphenylene sulfide oligomers, characterized in that: The following steps are involved: 1) washing and drying the polyphenylene sulfide oligomer; 2) mixing the polyphenylene sulfide oligomer washed and dried in step 1) with chain extender A and chain extender B; 3) extruding the mixture obtained in step 2); extrusion granulation adopts two sets of side feeds, the mixture enters the screw through side feed 1, and the nano calcium carbonate enters the screw through side feed 2, and the mass ratio is controlled by the loss-in-weight scale on the side feed, and extrusion granulation is performed; 4) drying after granulation to obtain granules; The chain extender A is ethylene maleic anhydride syndiotactic copolymer resin, and the chain extender B is triglycidyl isocyanurate.

2. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: The number average molecular weight Mn of the polyphenylene sulfide oligomer in step 1) is 15000-20000, and the washing and drying are specifically as follows: the polyphenylene sulfide oligomer is stirred and washed in pure water at 75-95° C. for 1-2 hours, filtered, and then dried in an oven at 100-130° C. for 3-6 hours.

3. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: In step 2), polyphenylene sulfide oligomer is mixed with chain extender A and chain extender B in a weight ratio of 100:(0.5-1.5):(0.5-1.5).

4. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: In step 2), the mixing speed is 100-200 r / min, and the mixing time is 10-30 min.

5. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: The process parameters adopted by the screw in step 3) are that the temperature of the extrusion granulation is set to 310-315°C in zone 1, 315-325°C in zone 2, 310-325°C in zone 3, 310-315°C in zone 4, and 300-320°C in zone 5, and the head temperature is set to 290-330°C.

6. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: The mass ratio of the nano-calcium carbonate used in step 3) to the polyphenylene sulfide oligomer in step 1) is (8-12):100, the average particle size of the nano-calcium carbonate is 50-80nm, and the purity is 95%-99%.

7. The long-chain branching modification method of polyphenylene sulfide oligomer according to claim 1, characterized in that: In step 4), the drying temperature is 100-130° C. and the drying time is 3-6 hours.

8. A polyphenylene sulfide product obtained by the modification method according to any one of claims 1 to 7.

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