CN113845760B

CN113845760B - Low-floating-fiber reinforced PBT/PET alloy composition and preparation method and application thereof

Info

Publication number: CN113845760B
Application number: CN202111166863.2A
Authority: CN
Inventors: 陈伟; 陈平绪; 叶南飚; 莫文杰; 龚德君; 冯健; 付学俊
Original assignee: Kingfa Science and Technology Co Ltd
Current assignee: Kingfa Science and Technology Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2023-03-28
Anticipated expiration: 2041-09-30
Also published as: CN113845760A

Abstract

The invention discloses a low-fiber-floating reinforced PBT/PET alloy composition, and a preparation method and application thereof. The low-floating-fiber reinforced PBT/PET alloy composition comprises the following components in parts by weight: 23-70 parts of PBT, 8-42 parts of PET, 10-40 parts of glass fiber, 3-7 parts of toughening agent, 2-4 parts of TMPTA, 1-3 parts of carbodiimide and 0.1-0.3 part of antioxidant. According to the invention, the synergistic effect of carbodiimide, TMPTA and the toughening agent is utilized, the surface gloss of the reinforced PBT/PET alloy composition after injection molding is effectively improved, the surface fiber floating is reduced, the surface fiber floating is still less after the material is subjected to three times of cyclic injection molding, the gloss is more than or equal to 65, and the excellent mechanical property is maintained.

Description

Low-floating-fiber reinforced PBT/PET alloy composition and preparation method and application thereof

Technical Field

The invention relates to the technical field of engineering plastics, in particular to a low-floating-fiber reinforced PBT/PET alloy composition, and a preparation method and application thereof.

Background

Polybutylene terephthalate (PBT) has the advantages of excellent long-term heat resistance, chemical reagent resistance, electrical insulation and the like, and is widely applied to industries such as electronic appliances, household appliances, cooling fans, illumination and the like. However, because the PBT resin has low mechanical strength, the mechanical property is improved by adding glass fiber.

However, due to the difference in fluidity between the glass fiber and the PBT and the poor compatibility between the glass fiber and the PBT, the addition of the glass fiber easily causes the glass fiber of the PBT injection molding product to leak, i.e., the phenomenon of fiber floating occurs, the surface gloss of the product is poor, and the mechanical stability of the PBT injection molding product is also influenced by the severe fiber floating condition.

At present, some prior arts report improved schemes for the fiber floating phenomenon of PBT injection molded products, but mainly for PBT products subjected to primary injection molding, the fiber floating situation of PBT subjected to multiple-cycle injection molding is not concerned. For example, the soldier (She Shibing, zhang Chao, luo Zhongfu. GF strengthens the performance and appearance of PBT/PET alloy [ J ] engineering plastics application, 2019,47 (01): 12-18.) discloses a glass fiber reinforced PBT/PET alloy, which improves the mechanical property and surface fiber floating condition of PBT/PET alloy injection molding products to a certain extent by introducing PET.

Under the condition of multiple times of circular injection molding of the reinforced PBT material, an interface layer on the surface of the glass fiber is further damaged under the action of frictional shear force in the processes of extrusion and injection molding, so that the compatibility between the glass fiber and resin is further deteriorated, and the binding force is also reduced. Therefore, after multiple cycles of injection molding, the fiber floating phenomenon of the PBT injection molded product is further aggravated, and the mechanical property of the material is further reduced.

In conclusion, there is a need to develop a reinforced PBT/PET alloy composition with low floating fiber, which has a smooth surface without floating fiber after the initial injection molding and can maintain the low floating fiber after multiple injection molding.

Disclosure of Invention

The invention aims to overcome the defects of surface floating fibers in the prior art, and provides the reinforced PBT/PET alloy composition with low floating fibers, the surface gloss of the reinforced PBT/PET alloy composition after injection molding is effectively improved by utilizing the synergistic effect of carbodiimide, TMPTA and a toughening agent, the surface floating fibers are reduced, the surface floating fibers are still less after the material is subjected to three times of cyclic injection molding, the gloss is more than or equal to 65, and the excellent mechanical property is kept.

Another object of the present invention is to provide a method for preparing the reinforced PBT/PET alloy composition.

Another object of the present invention is to provide the use of the above reinforced PBT/PET alloy composition.

In order to solve the technical problems, the invention adopts the technical scheme that:

a low-floating-fiber reinforced PBT/PET alloy composition comprises the following components in parts by weight:

23 to 70 portions of polybutylene terephthalate (PBT),

8 to 42 portions of polyethylene terephthalate (PET),

10-40 parts of glass fiber,

3 to 7 portions of toughening agent, namely,

2 to 4 portions of propane trimethanol triacrylate (TMPTA),

1 to 3 parts of carbodiimide,

0.1 to 0.3 portion of antioxidant.

During multiple-cycle injection molding, the ester groups in PBT and PET are easily hydrolyzed to generate carboxylic acid under the high-temperature injection molding condition due to external moisture, and the existence of the carboxylic acid can further aggravate the hydrolysis of the ester groups to cause the deterioration of the material performance. The addition of the carbodiimide can react with the generated carboxylic acid to generate stable ureide, so that the possibility of performance degradation caused by ester group hydrolysis reaction in the cyclic injection molding processing of the material is greatly reduced, and the retention rate of the cyclic injection molding performance for multiple times is greatly improved. Due to the prevention of the degradation and the performance deterioration of PET, the leakage of glass fiber in the composition is effectively reduced under the condition of multiple injection molding, and the reinforced PBT/PET alloy composition is further kept to have low fiber floating. Meanwhile, the TMPTA can improve the interface bonding force between the PBT resin and the glass fiber, improve the mechanical property of the composition, enhance the coating capability of the resin to the glass fiber and reduce the floating fiber of the material.

The inventor researches and discovers that under the combined action of carbodiimide and TMPTA, the leakage of glass fiber in a PBT/PET system can be effectively reduced, so that the reinforced PBT/PET alloy composition still keeps low fiber floating after multiple cycles of injection molding.

Preferably, the PBT in the reinforced PBT/PET alloy composition accounts for 35-60 parts by weight.

Preferably, the reinforced PBT/PET alloy composition contains 10-35 parts by weight of PET.

Preferably, the content of isocyanate in the carbodiimide is less than or equal to 10ppm.

More preferably, the carbodiimide has an isocyanate content of 5ppm or less.

The content of isocyanate in the carbodiimide is detected according to the GB 31604.45-2016 standard method.

Carbodiimide is usually prepared from isocyanate which is a small molecular organic substance, and excessive isocyanate residue can cause the isocyanate to migrate to the surface of an article during injection molding of the article, so that appearance defects of the surface of the article are generated. The inventor researches and discovers that when the content of isocyanate in the carbodiimide is less than or equal to 10ppm, the negative influence on the surface appearance of the product is not caused basically.

Preferably, the carbodiimide is N, N' -bis (2,6-diisopropylphenyl) carbodiimide and/or dicyclohexylcarbodiimide.

Preferably, the acid value of the TMPTA is less than or equal to 1mg KOH/g.

The acid value test method is based on GB/T264-1983.

When the acid value of the TMPTA is too high, the bonding force stability of the PBT or PET resin in the material to the glass fiber is reduced.

Preferably, the toughening agent contains ethylene and acrylate copolymerization units.

Preferably, the toughening agent is an ethylene-acrylate-glycidyl methacrylate terpolymer (E-MA-GMA).

More preferably, the content of Glycidyl Methacrylate (GMA) in the ethylene-acrylate-glycidyl methacrylate is not less than 7wt.%.

GMA is taken as a reactive functional group, and the higher the content of GMA, the better the interface connection effect between PBT and glass fiber in the reinforced PBT/PET alloy composition is.

Preferably, the glass fibers are treated with a coupling agent that is a blend of gamma-methacryloxypropyltrimethoxysilane and isopropylbis (methacryloyl) isostearoyl titanate.

Specifically, the treatment of the glass fiber by the coupling agent means that the glass fiber is dispersed in the coupling agent and stirred for 5-8 min at the temperature of 20-40 ℃. The inventor researches to find that the glass fiber treated by the gamma-methacryloxypropyltrimethoxysilane has better wetting and covering effects in PBT resin, and isopropyl di (methacryloyl) isostearoyl titanate has better wetting promotion effects on PET resin and glass fiber. In the PBT/PET system, the blend of gamma-methacryloxypropyltrimethoxysilane and isopropyl di (methacryloyl) isostearyl titanate is used as a coupling agent to carry out surface treatment on glass fibers, so that the surface floating of the composition can be greatly reduced; and a certain synergistic effect is achieved between the TMPTA and the coupling agent, and the synergistic effect of the coupling agent on resin impregnation and coating of the glass fiber can be promoted.

More preferably, the weight ratio of gamma-methacryloxypropyltrimethoxysilane to isopropylbis (methacryloyl) isostearoyl titanate in the coupling agent is 1: (0.8-1.2).

Preferably, the PBT has an intrinsic viscosity at 25 ℃ of 0.8 to 1.2dL/g.

The PBT intrinsic viscosity test method is in accordance with GB/T14190-2017.

Preferably, the PET has an intrinsic viscosity at 25 ℃ of 0.6 to 0.8dL/g.

The PET intrinsic viscosity test method is in accordance with GB/T14190-2017.

The PBT and PET resins in the viscosity range enable the reinforced PBT/PET alloy composition to have lower surface floating fiber and better mechanical property after multiple times of injection molding.

Preferably, the weight ratio of the PBT to the PET is (1-5): 1.

Preferably, the antioxidant is a hindered phenol antioxidant.

More preferably, the antioxidant is octadecyl beta (3,5 di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076) and/or 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) -1,3,5-triazine-2,4,6- (1H, 3H, 5H) -trione (antioxidant 1790).

The invention also provides a preparation method of the reinforced PBT/PET alloy composition, which comprises the following steps:

mixing a toughening agent, carbodiimide, TMPTA and an antioxidant to obtain a premix;

and mixing the premix, the PBT, the PET and the glass fiber, adding the mixture into an extruder, and performing melt mixing and extrusion granulation to obtain the reinforced PBT/PET alloy composition.

Preferably, the extruder is a twin screw extruder.

More preferably, the temperature of the first zone from the feeding port to the head of the double-screw extruder is 200-230 ℃, the temperature of the second zone is 230-260 ℃, the temperature of the third zone is 240-260 ℃, the temperature of the fourth zone is 240-270 ℃, the temperature of the fifth zone is 240-270 ℃, the temperature of the sixth zone is 240-270 ℃, the temperature of the seventh zone is 240-270 ℃, the temperature of the eighth zone is 220-240 ℃, the temperature of the ninth zone is 220-240 ℃, the temperature of the tenth zone is 240-270 ℃, and the screw rotating speed of the double-screw extruder is 200-450 rpm.

The invention also protects the application of the reinforced PBT/PET alloy composition in the preparation of electronic and electric appliances, cooling fans and lighting products.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the synergistic effect of carbodiimide, TMPTA and the toughening agent is utilized, the surface gloss of the reinforced PBT/PET alloy composition after injection molding is effectively improved, the surface fiber floating is reduced, the surface fiber floating is still less after the material is subjected to three times of cyclic injection molding, the gloss is more than or equal to 65, and the excellent mechanical property is maintained.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The raw materials in the examples and comparative examples are all commercially available;

in the examples and comparative examples, glass fiber-1 was a glass fiber treated with a coupling agent comprising gamma-methacryloxypropyltrimethoxysilane and isopropylbis (methacryloyl) isostearyl titanate in a weight ratio of 1:1 a blend; the glass fiber-2 is prepared by treating glass fiber with a coupling agent, wherein the coupling agent is gamma-methacryloxypropyltrimethoxysilane and isopropyl di (methacryloyl) isostearoyl titanate in a weight ratio of 1:1.2 blend; the glass fiber-3 is prepared by treating glass fiber with a coupling agent, wherein the coupling agent is gamma-methacryloxypropyltrimethoxysilane and isopropyl di (methacryloyl) isostearoyl titanate in a weight ratio of 1:0.8 blend; the glass fiber-4 is the glass fiber treated by a coupling agent, and the coupling agent is N- (beta-aminoethyl) -gamma-aminopropyltrimethoxysilane; the glass fiber-5 is glass fiber which is not treated by a coupling agent.

The reagents, methods and apparatus employed in the present invention are conventional in the art, except as otherwise indicated.

Examples 1 to 18

Examples 1 to 18 each provide a reinforced PBT/PET alloy composition having the component contents shown in Table 1, prepared as follows:

mixing the premix, PBT, PET and glass fiber, adding the mixture into a double-screw extruder, and performing melt mixing and extrusion granulation to obtain a reinforced PBT/PET alloy composition;

wherein the temperature of the twin-screw extruder from a feeding port to a first zone of a machine head is 200-230 ℃, the temperature of a second zone is 230-260 ℃, the temperature of a third zone is 240-260 ℃, the temperature of a fourth zone is 240-270 ℃, the temperature of a fifth zone is 240-270 ℃, the temperature of a sixth zone is 240-270 ℃, the temperature of a seventh zone is 240-270 ℃, the temperature of an eighth zone is 220-240 ℃, the temperature of a ninth zone is 220-240 ℃, the temperature of a tenth zone is 240-270 ℃, and the screw rotating speed of the twin-screw extruder is 200-450 rpm.

TABLE 1 component contents (parts by weight) of examples 1 to 18

	1	2	3	4	5	6	7	8	9	10
											PBT-1	35	35	35	35	35	35	35	35	35	35
PET-1	35	35	35	35	35	35	35	35	35	35
											Glass fiber-1	10	-	-	-	-	10	10	10	10	10
Glass fiber-2		10	-	-	-	-	-	-	-	-
											Glass fiber-3	-	-	10	-	-	-	-	-	-	-
Glass fiber-4	-	-	-	10	-	-	-	-	-	-
											Glass fiber-5	-	-	-	-	10	-	-	-	-	-
Flexibilizer-1	7	7	7	7	7	-	-	7	7	7
											Flexibilizer-2	-	-	-	-	-	7	-	-	-	-
Flexibilizer-3	-	-	-	-	-	-	7	-	-	-
											TMPTA-1	4	4	4	4	4	4	4	-	4	4
TMPTA-2	-	-	-	-	-	-	-	4	-	-
											Carbodiimide-1	3	3	3	3	3	3	3	3	-	-
Carbodiimide-2	-	-	-	-	-	-	-	-	3	-
											Carbodiimide-3	-	-	-	-	-	-	-	-	-	3
Antioxidant 1076	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1
											Antioxidant 1790	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1

/>

Comparative examples 1 to 6

Comparative examples 1 to 6 each provide a reinforced PBT/PET alloy composition, the contents of the components of which are shown in table 2, the preparation method being as follows:

mixing a toughening agent (if any), carbodiimide (if any), TMPTA (if any) and an antioxidant to obtain a premix;

wherein the temperature of the first zone from the feeding port to the machine head of the double-screw extruder is 200-230 ℃, the temperature of the second zone is 230-260 ℃, the temperature of the third zone is 240-260 ℃, the temperature of the fourth zone is 240-270 ℃, the temperature of the fifth zone is 240-270 ℃, the temperature of the sixth zone is 240-270 ℃, the temperature of the seventh zone is 240-270 ℃, the temperature of the eighth zone is 220-240 ℃, the temperature of the ninth zone is 220-240 ℃, the temperature of the tenth zone is 240-270 ℃, and the screw rotating speed of the double-screw extruder is 200-450 rpm.

TABLE 2 component contents (parts by weight) of comparative examples 1 to 6

	1	2	3	4	5	6
							PBT-1	35	35	35	35	70	20
PET-1	35	35	35	35	-	50
							Glass fiber-1	10	10	10	10	10	10
Flexibilizer-1	-	7	7	7	7	7
							TMPTA-1	4	-	4	1	4	4
Carbodiimido-1	3	3	-	0.5	3	3
							Antioxidant 1076	0.1	0.1	0.1	0.1	0.1	0.1
Antioxidant 1790	0.1	0.1	0.1	0.1	0.1	0.1

Performance testing

The reinforced PBT/PET alloy compositions prepared in the above examples and comparative examples were tested for their performance, the specific test methods were as follows:

the fiber floating condition on the surface:

the reinforced PBT/PET alloy composition is subjected to primary injection molding, secondary injection molding and tertiary injection molding, and the injection molding method comprises the following steps:

primary injection molding: drying the extruded and granulated PBT composition granules in a blast drying oven at 120 ℃ for 6h, and then performing injection molding by an injection molding machine to obtain a color plate with a smooth surface, wherein the size of the color plate is 60 multiplied by 3mm, namely the primary injection molding color plate;

secondary injection molding: crushing the color plate obtained by primary injection molding by using a crusher, drying the crushed particles in a blast drying oven at 120 ℃ for 6h, and then performing injection molding by using an injection molding machine to obtain a color plate with a smooth surface, namely a secondary injection molding color plate;

and (3) injection molding for three times: and (3) crushing the color plate obtained by secondary injection molding by using a crusher, drying the crushed particles in a blast drying oven at 120 ℃ for 6h, and then performing injection molding by using an injection molding machine to obtain the color plate with a smooth surface, namely the third injection molding color plate.

And respectively carrying out a glossiness test on the primary/secondary/tertiary injection molding sample strips, wherein the specific method for the glossiness test comprises the following steps:

using a gloss tester, the incident angle was 60 °.

(II) mechanical properties:

primary injection molding: drying the extruded and granulated PBT composition granules in a 120 ℃ forced air drying oven for 6 hours, and then performing injection molding by an injection molding machine to obtain an ISO standard mechanical sample strip, namely a primary injection molding sample strip;

secondary injection molding: crushing the mechanical sample strip obtained by primary injection molding by using a crusher, drying the crushed particles in a 120 ℃ forced air drying oven for 6 hours, and then performing injection molding by using an injection molding machine to obtain an ISO standard mechanical sample strip, namely a secondary injection molding sample strip;

and (3) injection molding for three times: and crushing the mechanical sample strip obtained by secondary injection molding by using a crusher, drying the crushed particles in a 120 ℃ blast drying oven for 6 hours, and then performing injection molding by using an injection molding machine to obtain an ISO standard mechanical sample strip, namely a tertiary injection molding sample strip.

Respectively carrying out mechanical property test on the primary/secondary/tertiary injection molding sample strips, wherein the specific method for the mechanical property test comprises the following steps:

tensile strength: measured according to ISO527-2012 standard method, unit is MPa;

notched impact strength: measured according to ISO180-2000 standard method, with kJ/m ² ；

Retention ratio: (test value of secondary injection or tertiary injection/corresponding test value of primary injection) × 100%.

Test results

The results of the performance tests of examples 1 to 18 are shown in Table 3, and the results of the performance tests of comparative examples 1 to 6 are shown in Table 4.

Table 3 results of performance testing of examples 1 to 18

According to the test results in Table 3, the reinforced PBT/PET alloy composition prepared in each embodiment of the invention is subjected to three times of cycle injection molding, the retention rate of tensile strength and notch impact strength is more than or equal to 75%, the glossiness is more than or equal to 65, and the glossiness of the three times of injection molding is less than or equal to 10 compared with the glossiness of the primary injection molding.

From examples 1 to 5, it can be seen that the surface fiber floating condition and mechanical properties of the composition after multiple injection molding can be affected by different coupling agent treatments for the glass fibers. The coupling agent is gamma-methacryloxypropyltrimethoxysilane and isopropyl di (methacryloyl) isostearyl titanate according to the weight ratio of 1: (0.8-1.2), the reinforced PBT/PET alloy composition has less fiber floating, higher glossiness and higher mechanical property retention rate.

From the embodiment 1 and the embodiments 6 to 7, the toughening agent is preferably E-MA-GMA, and when the content of GMA in the E-MA-GMA is more than or equal to 7%, the glossiness of the enhanced PBT/PET alloy composition is better. As can be seen from the data of example 1 and examples 8-10, the enhanced PBT/PET alloy composition has better overall performance when the acid value of TMPTA is less than or equal to 1.0mg KOH/g and the content of isocyanate in carbodiimide is less than or equal to 10ppm.

From the examples 1 and 14 to 18, when the mass ratio of the PBT to the PET satisfies (1 to 5): 1, the reinforced PBT/PET alloy composition has less reduction in the gloss, better fiber floating, and higher mechanical property retention.

TABLE 4 results of the Performance test of comparative examples 1 to 6

According to the test results in Table 4, when the comparative examples 1-3 do not contain the toughening agent, TMPTA or carbodiimide respectively, the mechanical property retention rate of the reinforced PBT/PET alloy composition is only about 60% through three times of cycle injection molding, and the gloss reduction value reaches more than 14, compared with the initial injection molding, the gloss reduction ranges of the comparative examples 1-3 respectively reach 20%, 21% and 22%, namely the fiber floating condition of the material is seriously degraded after multiple injection molding. When the amounts of TMPTA and carbodiimide in comparative example 4 were too small, it was difficult to achieve the low level of floating fiber equivalent to that of example. The reinforced PBT/PET alloy composition of comparative example 5, which contained no PET, had poor gloss after the first injection molding, only 62, and further reduced gloss and severe surface floating after the second and third injection molding. In the comparative example 6, the PBT content is too low, the PET content is too high, the PBT/PET matrix of the reinforced PBT/PET alloy composition has poor comprehensive performance, and the surface floating fiber and the mechanical property of the material are influenced.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The low-floating-fiber reinforced PBT/PET alloy composition is characterized by comprising the following components in parts by weight:

23 to 70 parts of PBT, 8 to 42 parts of PET, 10 to 40 parts of glass fiber, 3 to 7 parts of flexibilizer, 2 to 4 parts of TMPTA, 1 to 3 parts of carbodiimide, 0.1 to 0.3 part of antioxidant,

the content of isocyanate in the carbodiimide is less than or equal to 10ppm,

the acid value of the TMPTA is less than or equal to 1mg KOH/g,

the toughening agent contains ethylene and acrylate copolymerization units.

2. The reinforced PBT/PET alloy composition of claim 1, wherein the toughening agent is an ethylene-acrylate-glycidyl methacrylate terpolymer.

3. The reinforced PBT/PET alloy composition of claim 1, wherein the glass fiber is treated with a coupling agent which is a blend of gamma-methacryloxypropyltrimethoxysilane and isopropyldi (methacryloyl) isostearyl titanate.

4. The reinforced PBT/PET alloy composition of claim 1, wherein the PBT has an intrinsic viscosity at 25 ℃ of 0.8 to 1.2dL/g; the intrinsic viscosity of the PET at 25 ℃ is 0.6-0.8 dL/g.

5. The reinforced PBT/PET alloy composition of claim 1, wherein the weight ratio of the PBT to the PET is (1-5): 1.

6. Process for the preparation of a reinforced PBT/PET alloy composition according to any one of claims 1 to 5, characterized in that it comprises the following steps:

7. Use of the reinforced PBT/PET alloy composition of any one of claims 1 to 5 for the production of electronic appliances, cooling fans, lighting products.