CN112708266B - High-filling heat-conducting PA6/PP composite material with good glue adhesion and application thereof - Google Patents

Abstract

The application discloses high heat conduction PA6/PP combined material that fills with good glue adhesion, by weight, includes following component: the heat-conducting composite material comprises, by weight, 620-40 parts of PA, 1-15 parts of PP, 35-50 parts of heat-conducting filler, 5-25 parts of reinforcing filler, 1-5 parts of compatilizer, 1-5 parts of flexibilizer, 0.1-5 parts of other auxiliary agents and 0.1-1 part of polyol stearate lubricant. The alloy of PA6 and PP is passed through to this application, solves the material mobility that PA6 high filling leads to poor, the poor and many cave processing defects's of thin wall problem of low temperature toughness. The lubricant performance of the polyol stearate lubricant in the resin processing process can be fully utilized, the adhesion force of the glue can be enhanced when the product is bonded with the glue, the torque of the bubble shell is improved, and the performance requirement of the product is met.

Description

High-filling heat-conducting PA6/PP composite material with good glue adhesion and application thereof

Technical Field

The invention belongs to the field of high molecular compound compositions, and particularly relates to a high-filling heat-conducting high molecular compound composite material.

Background

The heat conducting material is commonly used in heat radiating devices in the LED lighting industry, and along with the development of the industry, the requirements on cost reduction, heat conduction and flame retardance of the material are higher and higher. The high filling of the filler can improve the heat conduction and flame retardant properties of the material, and therefore, more and more heat conduction material formulas are researched greatly. The heat conducting material and the reinforcing filler account for more than 40% to meet the requirement, but the high filling material has poor fluidity and toughness, the thin-wall product is difficult to process, and the brittleness is high, and the defects are more obvious particularly in the LED lamp housing made of the white heat conducting material (or the heat conducting insulating material). Therefore, there is a need to improve the flowability of materials and to toughen the materials.

For the heat-conducting material resin matrix, the PA66 is high in cost and high in system viscosity, so that the PA66 is not suitable for being applied to a high-filling heat-conducting material system. PA6 (nylon 6) is an important engineering plastic, has the characteristics of excellent mechanical property, self-lubricating property, chemical corrosion resistance, good molding processing and the like, and is widely applied to a plurality of fields. The choice of PA6 as the base resin of LED lamp housing can further control the material cost, but the application of PA6 still has the following processing problems:

1) due to the requirement of heat conduction, the proportion of the heat-conducting filler and the reinforcing filler in the heat-conducting PA6 material is high, usually more than 50%, which causes poor material flowability;

2) the PA6 heat-conducting material has poor low-temperature toughness in winter, mainly shows assembly cracking, further reduces the toughness of the material under the condition of high filling, and has casting problem in the hot runner processing process;

3) the PA6 heat conduction material has processing defects of difficult filling, glue shortage and the like when adopting a thin-wall multi-hole processing mode.

The product processing runner is divided into a cold runner and a hot runner for processing according to the temperature, and compared with the cold runner for processing, the hot runner sprue can be opened very little, the appearance of a finished piece is not influenced, the processing produced waste is less, the production efficiency is high, the automation degree is high, the material cost is saved, and the cold runner processing technology is gradually replaced. However, many materials are not suitable for hot runner processing, such as temperature difference resistant flame retardant systems, which can cause problems such as material degradation or flame retardant failure. The problem of degradation or flame retardant failure is solved through the mode that reduces hot runner temperature, can make the fuse-element viscosity increase, be unfavorable for processing, appearance defects such as starved atmosphere appear even.

In addition, the hot runner processing needs to strictly control the melt viscosity, on one hand, the melt fluidity needs to be improved due to the processing technology, and on the other hand, the problem of casting caused by low viscosity needs to be avoided. The high heat conduction efficiency is realized because of the high packing of heat conduction material needs, and melt viscosity is higher usually, and mobility is poor, and difficult processing especially to thin wall product (the wall thickness is less than 1mm), and the finished piece advances to glue mouthful and far away runner thickness difference is great, changes the phenomenon that nearly gluey mouthful end flies the edge far away runner mouth and lacks glue. None of the known nylon-based heat conducting materials solves the aforementioned problems. Many highly filled thermally conductive materials would therefore choose a cold runner process.

The silicone adhesive belongs to silica gel glue, has the advantage of good weather resistance, and is widely used as a structural sealant in the LED illumination industry, however, the single-component sealant has poor adhesion, and in a highly-filled nylon material, the resin matrix part is relatively reduced due to the high filling of the filler, so that the polarity of the material is reduced, and the adhesion between a product and the silicone adhesive is further reduced. While the PA6 processing problem is solved, the polarity of the material is easy to reduce, so that the adhesion force with silicone adhesive is difficult to meet the requirement of the standard of GB 24906-2010 safety requirement for self-ballasted LED lamps above 50V for common illumination on the torque of the PC bulb, namely the torque of the PC bulb is less than 3 N.m in the actual assembly process.

In the prior art, the torque of the PC bulb shell is improved in three directions by replacing glue, performing post-treatment (such as plasma flame, surface treatment agent and the like) on a workpiece and improving a formula. The influence of replacing glue on other properties of the alloy material is uncontrollable, and in the common glue, the silicone adhesive is polar adhesive, so that the weather resistance is good, the defects are poor adhesion, and the weather resistance requirement of the lighting industry needs to be met; the post-processing mode of the workpiece can increase the complexity of the processing technology, reduce the yield and improve the production cost. Therefore, it is a reasonable direction to start with the improvement of the formula. In order to improve the torque of the PC shell, a person skilled in the art may think of increasing the polarity of the surface of the material and the adhesion force with the glue by adding a polarity auxiliary agent into the material system. If a polar lubricant is added, the problem can be solved, such as selecting a commonly used lubricant EBS with stronger polarity; although the coupling agent has certain polarity, the surface polarity of the material can be improved to a certain extent, but the material fluidity is greatly influenced, and the coupling agent is a liquid raw material conventionally, so that the production cost is high, and production equipment is difficult to clean.

Disclosure of Invention

In order to solve the foregoing problems in the prior art, an object of the present invention is to provide a highly filled heat conductive PA6/PP composite material with good adhesive force of glue, which has good processing flowability and low-temperature toughness, meets the requirements of hot runner thin-wall multi-cavity processing technology, has strong adhesive force with silicone adhesive, and is specifically realized by the following technical scheme:

a high-filling heat-conducting PA6/PP composite material with good glue adhesion comprises the following components in parts by weight:

PA620～40

PP 1～15

35-50 parts of heat-conducting filler

5-25 parts of reinforcing filler

1 to 5 parts of a compatibilizer

1-5 parts of toughening agent

0.1-5% of other additives

0.1-1% of polyol stearate lubricant.

Optionally, the polyol stearate lubricant comprises one or more of trimethylolpropane stearate, glycerol stearate and pentaerythritol stearate.

Optionally, the heat conductive filler includes one or more of magnesium hydroxide, calcium carbonate, magnesium oxide, aluminum nitride, boron nitride, silicon carbide, molybdenum disulfide, zinc sulfide, wollastonite, and talc.

Optionally, the compatibilizer or toughening agent is one or more of an EPDM-grafted maleic anhydride copolymer, a polypropylene-grafted maleic anhydride copolymer, and a POE-grafted maleic anhydride copolymer.

Optionally, the other auxiliary agent is one or more of an antioxidant and a toner.

Optionally, the PP is a co-PP resin.

The application also provides an application of the composite material in any technical scheme in the hot runner processing technology of thin-wall products to solve the problem of processing and casting.

Optionally, the wall thickness of the thin-walled product is less than 1.0 mm.

Optionally, the injection molding temperature of the hot runner processing technology is 250-280 ℃, and the hot runner temperature is 200-300 ℃.

The application also provides an application of the composite material in any one of the technical schemes in lamp housings in the LED lighting industry. Including but not limited to bulb, downlights, T-lights, spot lights, candle lights.

The application also provides a use of the polyol stearate lubricant in the composite material according to any one of the preceding claims for increasing adhesion between a composite article and a silicone adhesive.

Optionally, the composite material product is subjected to a damp-heat environment treatment, wherein the damp-heat environment treatment comprises a separate temperature and humidity increasing treatment process, or one or more treatment modes of the product in a storage environment, a transportation environment, an assembly process environment and a temperature and humidity environment in which heat is generated by the LED during work in a user use process.

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

the problem of the material mobility that PA6 high filling leads to is poor, low temperature toughness is poor and many cave processing defects of thin wall is solved through the complex of PA6 and PP in this application. Compared with PA6 material, PP has the phenomenon that low shear viscosity is big, strong shear viscosity is little, is used in high packing heat conduction nylon material, and at the end of nearly pouring gate, because the finished product wall thickness is relatively great, the shear rate of production is little, causes melt viscosity big, can solve the overlap problem, at the end of far pouring gate, because the finished product wall thickness is relatively less, the shear rate of production is big, causes melt viscosity less, can solve the scarce gluey problem.

The adhesion of the materials described in this application to silicone adhesives has not been studied in the prior art for the effect of the part on the torque of PC bulbs during assembly. Particularly, due to the structural limitation of the LED shell, when the assembling contact surface of the PC bulb shell is small or the silicone adhesive coating is thin, the torque of the PC bulb shell needs to be further improved, and some components even fall below the standard torque requirement of the PC bulb shell of a corresponding component, so that the components cannot be normally used.

In order to improve the adhesion between the parts and the silicone adhesive, an EBS polar lubricant is generally an alternative for those skilled in the art, but the practical use in the system is not resistant to precipitation, the parts can precipitate after being naturally placed, and the practical result is that the torsion performance of the parts on the cell shell is poor, and the requirements of the parts on the torsion of the PC cell shell are difficult to meet.

The polyol stearate lubricant comprises trimethylolpropane stearate, glycerol stearate and pentaerythritol stearate, wherein PETS (pentaerythritol stearate) is a common lubricant and plasticizer in resin processing. It is easily inferred by those skilled in the art from the results of the aforementioned polar lubricant EBS evolution during use resulting in a decrease in the cell shell torque: lubricant such as PETS described in the application is also easy to be separated out to the surface of the material, and can be increased to be separated out under certain temperature and humidity conditions, so that the adhesive force of glue and resin is reduced, and the torque of the foam shell is further reduced. Furthermore, EBS improves the fluidity of the system relatively well, so EBS is generally preferred as a system lubricant. However, practical tests of the application find that after certain temperature and humidity environment treatment (such as the process before production and gluing, the storage process, the transportation process and the environment such as the heating of the LED lamp in the subsequent lamp housing using process), a polyol stearate lubricant formula system similar to PETS should be precipitated and increased to reduce the adhesive force of glue, but actually the torque of the PC bulb shell is increased.

According to the experimental result trial and inference that the application is not in accordance with the common sense prediction, as the material system of the application is alkaline, polyol stearate such as PETS is easily hydrolyzed into stearic acid and pentaerythritol with stronger polarity under a certain temperature and humidity condition, the surface polarity of the material can be enhanced, so that the adhesion force with silicone glue is improved, and the torque of the PC foam shell is improved.

The lubricant performance of the polyol stearate lubricant in the resin processing process can be fully utilized, the adhesion force of the glue can be enhanced when the product is bonded with the glue, the torque of the bubble shell is improved, and the performance requirement of the product is met.

The composite material can fully utilize the temperature and humidity conditions of the process of storage, gluing, sending to a product manufacturer and finally using by a user after the product is produced to carry out 'pretreatment', so that the adhesion of the product and the glue can be further improved, and the requirement of different structural products on the torque of the PC foam shell in the GB 24906 plus 2010 standard can be met.

The PA6/PP composite material is particularly suitable for products which adopt hot runners, thin-wall multi-hole processing technologies and the like, have heat conduction and flame retardance requirements and are difficult to meet the torque requirements of PC cell shells.

Drawings

Fig. 1 is a schematic structural view of an LED lamp housing sample prepared according to an embodiment of the present application;

FIG. 2 is a schematic of the state after the blister torque test for samples prepared from the formulation of comparative example 2;

fig. 3 is a schematic of the samples prepared from the formulation of example 1 after the blister torque test.

Detailed Description

The technical solutions of the present invention are further described below with reference to specific embodiments, and it should be noted that the specific embodiments described in the embodiments of the present invention are not intended to limit the claims of the present invention.

The related terms of the application explain:

EPDM (i.e., ethylene propylene diene monomer) grafted maleic anhydride copolymer is also commonly referred to as EPDM-g-MAH

POE (ethylene octene copolymer) grafted maleic anhydride copolymer is also commonly written as POE-g-MAH

PP (Polypropylene) grafted maleic anhydride copolymers are also commonly written as PP-g-MAH

The raw materials used in the examples of the application are as follows:

PA 66: wenzhou Huafeng group, EP1107

PA 6: m2000, Nitrilon, Inc., of Guangdong Xinhui

PP: yongjia Ding 1450T

EPDM-g-MAH: dongguan Kadaler plastic raw material

PP-g-MAH: shenyang four-dimensional Polymer plastics Co., Ltd, SWJ-1B

POE-g-MAH: WEK-108, a science and technology company Limited for New Material

Glass fiber: jushi group Ltd, ECS10-4.5-560A

Magnesium hydroxide: dacrico mineral products Ltd

Calcium carbonate: jiangxi Yongfa chemical Co., Ltd

Ethylene Bis Stearamide (EBS): guangzhou Peak China chemical technology Co Ltd

Pentaerythritol stearate (PETS): petrochemical of Jiangsu Haian

Silicone lubricant: new materials of Lanxing (Chengdu) Co., Ltd., GM-100

Antioxidant: an antioxidant 1098.

The materials of the examples and comparative examples were prepared as follows:

the production method is characterized by adopting a melt blending extrusion process, mixing raw material components except the glass fiber in a high-speed mixing pot at normal temperature and high speed for 10-15 min, adding the obtained mixture into a double-screw extruder through a main feeding port, feeding the glass fiber into the double-screw extruder from a side feeding port, extruding after melt blending, cooling, air drying and granulating to obtain the materials of each embodiment and comparative example.

And (3) a sample injection molding process: the materials of each embodiment and comparative example are added into an injection molding machine with a hot runner, the injection molding temperature is 250-280 ℃, and the hot runner temperature is 200-300 ℃. The injection molded sample was an LED lamp housing of less than 1 mm. The fracture surface of the lamp envelope is shown in fig. 1.

The performance test method of the application is as follows:

unnotched impact strength: GB/T1843-2008;

flame retardant rating: 125X 13X 3.2mm were produced by injection molding and tested according to UL-94 standard.

Coefficient of thermal conductivity: the particles were injection molded into 12.7X 2mm round pieces and tested for thermal conductivity at 25 ℃ using a relaxation-resistant laser thermal conductivity meter.

The processability can be evaluated by three aspects of the ejection pressure, the ejection speed and the casting. The injection pressure and the injection speed are set as lower limits, and the pressure maintaining pressure and speed are not set, so that the product is just filled, and the lowest pressure and speed are provided, and the lower the pressure and speed are, the better the fluidity is reflected; casting performance: and observing the casting phenomenon in the processing process and evaluating the casting performance.

Surface precipitation: surface deposition was assessed by visual observation.

The PC bulb shell torque test method comprises the following steps: after the lamp shell is glued, the lamp shell is assembled with a PC (polycarbonate) bulb shell and placed for 24 hours, after the glue is cured, the lamp cap is riveted, and then a torque tester is used for testing the torque of the bulb shell; the PC bulb torque can also be reflected to some extent by the adhesion of the part to the silicone adhesive glue.

The method for evaluating the adhesion between the workpiece and the silicone adhesive glue comprises the following steps: placing the injection-molded color plate in a natural environment for 1 week, peeling the part and glue by hand after the glue is spread on the surface of the color plate for 24 hours and is cured, and explaining the adhesive force grade of the glue and the material adhesive force part:

level 1: very easy to be stripped

And 2, stage: easy to peel off

And 3, level: is difficult to be stripped

4, level: difficult to peel off

And 5, stage: very difficult to peel off.

Aiming at the adhesion test, the surface precipitation condition and the hand tearing score of the test material are respectively measured before and after the temperature and humidity treatment, wherein the temperature and humidity treatment adopts double 85 experimental treatment, and the specific steps are as follows: the material is injected into a color plate and is put into a high-temperature and high-humidity box with 85 ℃ and 85% RH humidity for treatment, and the purpose is as follows: accelerating the precipitation of the material auxiliary agent.

The materials of the formulations used in example 1 and comparative example 2 were molded into lamp parts as shown in fig. 1, and the PC bulb torque was measured after natural standing for 1 day, 2 days, and 7 days, respectively, and the data is shown in table 2.

The formulations (parts by weight) and performance data used in the examples and comparative examples are shown in Table 1.

The data in table 1 show that: compared with the comparative example 1 and the comparative example 2, the PA6/PP alloy is used, so that the injection pressure and the injection speed of the system are reduced, and the processing flowability is improved; but also improves the problem of flow during processing, but the PA6/PP system has a reduced material adhesion grade compared with the PA6 system alone, because the addition of the PP reduces the polarity of the PA6 resin and reduces the adhesion of the resin to the silicone adhesive. Similarly, the improvement effect of the processing and casting of the PA6/PP alloy system is also shown in examples 1 to 7.

In the PA6/PP alloy system of the comparative example 2, EBS is adopted as the lubricant, and compared with the PETS lubricant adopted in the examples 1-7, the lubricant has poor precipitation resistance, and the adhesion grades are in opposite trends before and after the double 85 experimental treatment; the PETS lubricant system showed a tendency to increase adhesion ratings, while the EBS lubricant system resulted in a decrease in adhesion ratings after processing, probably due to its greater effect on bleeding.

The test data of example 1 and example 3 show that the adhesion rating decreases with increasing PP content in the PA6/PP system. The reason is that PP itself has a low polarity, and as the amount of PP added increases, the polarity of the entire alloy material decreases, thereby decreasing the adhesion of the alloy material.

Comparative example 3 using GM-100 lubricant, the process casting problem was relatively improved, the injection pressure and injection speed were unchanged, and the adhesion rating was unchanged after the double 85 experimental treatment, compared to the EBS lubricant of comparative example 2; but the precipitation resistance was reduced after the double 85 test treatment.

Table 1 examples and comparative examples use the formulation (parts by weight) and performance data.

Table 2 PC bulb torque data after various time post-treatment of the molded parts of example 1 and comparative example 2.

From the data in table 2, it can be seen that: because the sample structure of the embodiment is a thin-wall multi-hole structure and is processed by adopting a hot runner processing mode, the torque requirement of the PC bulb shell is more than 3 N.m, but the sample (sample 1) is still difficult to meet the requirement when placed for 1 day, but the placing time is prolonged, the requirement is met, the reject ratio of the product production is reduced, and the production efficiency of qualified products is improved.

Compared with the EBS system of the comparative example 2, after the lamp housing sample is prepared, the PC bulb housing torque of the lamp housing sample is increased along with the prolonging of the placing time of the sample in the natural environment, and the increment is obvious; and the EBS lubricating system has the advantage that the torque of the PC cell shell of the sample is reduced as a whole along with the prolonging of the placing time of the sample in the natural environment, and most of the torque of the PC cell shell is reduced below the standard, so that the actual use requirement cannot be met.

In addition, two 85 experimental treatments in this application embodiment are one of the condition of humiture processing with place the processing naturally, and wherein place the processing naturally and can also place naturally in the warehouse, the environment in assembly, the transportation, the humiture processing of this application also can utilize the luminous heat that brings of LED when using, further promotes PC cell-shell moment of torsion.

Fig. 1 is a schematic view of an LED lamp housing made according to the present application; FIG. 2 is a graph of the post-blister torque test condition of samples prepared according to the formulation of comparative example 2 of the present application, showing that the silicone adhesive adheres primarily to the PC blisters and adheres poorly to the samples; FIG. 3 is a graph of the post-blister torque test condition of samples prepared according to the formulations of example 1 of the present application, showing that the silicone adhesive adheres primarily to the samples, reflecting to some extent the difference in adhesion between the two formulations.

It should be noted that the above contents described in the present specification are only illustrations of the technical solutions of the present invention. All simple and equivalent changes, which are made according to the characteristics and principles described in the present patent concepts, are included in the scope of protection of the present patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the technical spirit of the invention or exceeding the scope of the claims.

Claims (10)

1. A high-filling heat-conducting PA6/PP composite material with good glue adhesion is characterized by comprising the following components in parts by weight:

PA6 20~40；

PP 1~15；

35-50% of heat-conducting filler;

5-25 parts of a reinforcing filler;

1-5 parts of a compatilizer;

1-5 parts of a toughening agent;

0.1-5% of other auxiliary agents;

0.1-1% of polyol stearate lubricant.

2. A composite material according to claim 1, wherein the polyol stearate lubricant comprises one or more of trimethylolpropane stearate, glycerol stearate, pentaerythritol stearate.

3. The composite of claim 1, wherein the thermally conductive filler comprises one or more of magnesium hydroxide, calcium carbonate, magnesium oxide, aluminum nitride, boron nitride, silicon carbide, molybdenum disulfide, zinc sulfide, wollastonite, and talc.

4. The composite of claim 1, wherein the compatibilizer or toughening agent is one or more of an EPDM grafted maleic anhydride copolymer, a polypropylene grafted maleic anhydride copolymer, and a POE grafted maleic anhydride copolymer.

5. The composite material of claim 1, wherein the other auxiliary agent is one or more of an antioxidant and a toner.

6. Use of a composite material according to any one of claims 1 to 5 in a hot runner process for thin walled products to solve the problem of casting.

7. The use according to claim 6, wherein the hot runner process has an injection temperature of 250-280 ℃ and a hot runner temperature of 200-300 ℃.

8. Use of the composite material of any one of claims 1 to 5 in lamp housings in the LED lighting industry.

9. Use of a polyol stearate lubricant for increasing the adhesion between a composite article and a silicone adhesive, wherein the composite article is prepared from a composite material according to any of claims 1 to 5, and wherein the polyol stearate lubricant is derived from a composite material according to any of claims 1 to 5.

10. The use according to claim 9, wherein the composite article is subjected to a hot and humid environment treatment comprising one or more of a separate temperature and humidity increasing treatment process or a treatment using the article in a storage environment, a transportation environment, an assembly process environment, and a temperature and humidity environment in which the LEDs generate heat during use by a user.

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