Elastomer composite material for injection molding foaming encapsulation as well as preparation method and application of elastomer composite material

Abstract

The invention discloses an elastomer composite material for injection molding foaming encapsulation as well as a preparation method and application of the elastomer composite material. The elastomer composite material comprises the following raw materials in parts by weight: 100 parts of a hydrogenated styrene elastomer matrix; 10-50 parts of a special chain segment styrene elastomer; 20 to 60 parts of a polyolefin elastomer; 50 to 100 parts of a plasticizer; 2 to 20 parts of a maleic anhydride graft; 1 to 5 parts of tert-butyl peroxide; 0.5-10 parts of a foaming agent; and 0.5-5 parts of an anti-oxidation and anti-ultraviolet auxiliary agent. Compared with a traditional double-color injection molding process, the injection molding foaming process has the advantages of being soft in hand feeling, excellent in rebound resilience, fine and smooth in foaming, good in appearance, firm in rubber coating, capable of insulating sound and reducing noise.

Description

Technical Field

[0001] The invention relates to the technical field of polymer modification, in particular to an elastic composite material for injection molding, foaming and encapsulation, and a preparation method and application thereof. Background Art

[0002] Soft-touch car interiors can not only improve the grade of cars, but also enhance the driving and riding comfort of consumers, and are favored by more and more consumers and OEMs. Traditional soft interiors are made by first preparing a soft skin, and then bonding it with a PP skeleton through polyurethane foaming. Although it feels good, the mold and process are relatively complex, the cost is high, and it is very difficult to recycle in the later stage, and it is impossible to separate the thermosetting foam layer and the thermoplastic skeleton well. At present, with the increasingly fierce competition in the automobile industry, higher requirements are put forward for cost reduction and efficiency improvement in the automobile industry, which has derived the demand for injection molding foam encapsulated materials. Compared with dense materials, foam materials are characterized by low density, light weight, large specific area, high specific mechanical properties, good damping performance, and certain sound insulation and noise reduction characteristics. The ability to encapsulate can reduce production steps, speed up production rhythm, and play a role in reducing costs and increasing efficiency. Since foamed elastomers and PP have very good compatibility, when the car is scrapped, there is no need to separate the elastomer and PP skeleton separately. They can be crushed and granulated together for reuse. Therefore, injection molding foam encapsulated elastomers have good application prospects in the automotive field. Summary of the invention

[0003] The main purpose of the present invention is to provide an elastomer composite material for injection molding foaming and encapsulation, and its preparation method and application, which replaces the traditional automobile interior covering molding scheme, and has the advantages of high molding efficiency, low product cost, soft hand feeling, low density, good sound insulation and noise reduction effect, and recyclability. The formula of the thermoplastic elastomer material is optimized by modification to improve the processability, foaming, encapsulation and temperature and weather resistance of the thermoplastic elastomer material, so that it is suitable for automobile interior and exterior products with high hand feeling and appearance requirements.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0005] The invention discloses an elastomer composite material for injection molding foaming encapsulation, wherein the raw materials thereof include, by weight: 100 parts of a hydrogenated styrene elastomer matrix; 10 to 50 parts of a special segment styrene elastomer; 20 to 60 parts of a polyolefin elastomer; 50 to 100 parts of a plasticizer; 2 to 20 parts of a maleic anhydride graft; 1 to 5 parts of tert-butyl peroxide; 0.5 to 10 parts of a foaming agent; and 0.5 to 5 parts of an antioxidant and anti-ultraviolet auxiliaries.

[0006] According to one embodiment of the present invention, the raw materials include, by weight, 100 parts of hydrogenated styrene elastomer matrix; 20 parts of special segment styrene elastomer; 30 parts of polyolefin elastomer; 80 parts of plasticizer; 10 parts of maleic anhydride graft; 2 parts of tert-butyl peroxide and 3 parts of antioxidant and anti-ultraviolet additives.

[0007] According to one embodiment of the present invention, the hydrogenated styrene elastomer matrix is ​​selected from one or a composite of SEBS (hydrogenated styrene-butadiene-styrene triblock copolymer), SEPS (hydrogenated styrene-isoprene-styrene triblock copolymer), and SEEPS (hydrogenated styrene-ethylene-isoprene-styrene block copolymer).

[0008] According to one embodiment of the present invention, the special segment styrene elastomer has the following characteristics: the styrene block content at both ends is 20-40%; the middle butadiene segment contains a special monomer, the monomer accounts for 10-30%, and the monomer is selected from one or more of ethylene, ethylene norbornene, propylene, styrene, acrylonitrile, tetrahydrofuran, and polyols.

[0009] According to an embodiment of the present invention, the polyolefin elastic elastomer is selected from one or a combination of POP, EPDM, OBC, and POE.

[0010] According to one embodiment of the present invention, the raw materials for preparing the maleic anhydride grafted material are: 100 parts of styrene elastomer, 1 to 10 parts of maleic anhydride monomer, 0.15 to 0.8 parts of dicumyl peroxide (DCP), 0.01 to 0.08 parts of antioxidant (1076) and 0.01 to 0.08 parts of antioxidant (9228), and 0.01 to 0.3 parts of TiCl4 catalyst.

[0011] According to one embodiment of the present invention, the method for preparing the maleic anhydride grafted product comprises the following steps:

[0012] S410: Extruding and granulating the corresponding weight portions of styrene elastomer matrix, antioxidant and catalyst through a twin-screw extruder at a speed of 200 to 550 r / min and a temperature of 165 to 200° C. to prepare masterbatch A;

[0013] S420: stirring and dissolving maleic anhydride monomer and crosslinking agent in corresponding weight parts at 10-30° C. to prepare sulfide liquid B, wherein the stirring speed is 20-80 r / min;

[0014] S430 grafting reaction, master batch A, sulfide liquid B, graft cross-linking in a twin screw to form maleic anhydride grafted material, the speed of the twin screw is 300-600r / min, the reaction temperature is 160-205°C, and maleic anhydride grafted material particles are formed by underwater pelletizing.

[0015] According to one embodiment of the present invention, the plasticizer is high-viscosity paraffin oil, the kinematic viscosity of the paraffin oil at 40° C. is not less than 60 mm 2 / s, the flash point is not less than 270° C., and the CP value is greater than 65%.

[0016] According to one embodiment of the present invention, the tert-butyl peroxide is selected from one or more of diisopropylbenzene peroxide (DCP), 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (BPMC), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPMH), and 1,3-bis(tert-butylperoxyisopropyl)benzene (BIPB).

[0017] According to one embodiment of the present invention, the foaming agent is selected from one or more of sodium bicarbonate, sodium bicarbonate foaming masterbatch, azodicarbonamide, AC foaming masterbatch, and microsphere foaming masterbatch.

[0018] According to one embodiment of the present invention, the antioxidant and anti-ultraviolet agent are selected from one or more of 1010, 1076, 1330, 1024, 168, 626, DLTDP, UV531, UV326, UV328, UV329, UV234, UV770, UV944, and UV622.

[0019] A method for preparing an elastomer composite material for injection molding foam encapsulation comprises the following steps:

[0020] S100: Evenly mix the corresponding weight portions of styrene elastomer matrix, special segment styrene elastomer, plasticizer, polyolefin elastomer, maleic anhydride grafted material, and antioxidant and anti-ultraviolet agent through a high-speed mixer or a coloring machine;

[0021] S200 uses a peristaltic pump to inject the corresponding weight portion of tert-butyl peroxide through the reserved injection holes in the 2nd to 8th sections of the screw, which is called pump A;

[0022] According to one embodiment of the present invention, the preparation method of the elastomer composite material for injection molding foaming and encapsulation further comprises the steps of: S300 adjusting the feeding speed of the twin-screw extruder and the speed of the A pump to achieve the corresponding material ratio, wherein the twin-screw speed is 200-650r / min, the twin-screw temperature is 180-250°C, and the weight loss scale feeding is turned on when the screw reaches a specific speed, and the A pump is turned on after 1 minute. After underwater pelletizing and granulation, the elastomer composite material for injection molding foaming and encapsulation is obtained.

[0023] According to an embodiment of the present invention, the temperature of the coloring machine in step S100 is 20-60° C., the mixing speed is 10-500 r / min, the temperature of the tert-butyl peroxide in step S200 is 0-10° C., and the speed of pump A is 5-50 r / min.

[0024] According to an embodiment of the present invention, the tert-butyl peroxide used in step S200 is volatile and flammable, so the peroxide is mixed with mineral oil in a ratio of 1:2 and then placed in a refrigerator for cooling before use. The refrigerator temperature is set to 0°C.

[0025] An application method of an elastomer composite material for injection foaming and encapsulation as claimed in claim 1, comprising the following steps: uniformly mixing the prepared elastomer composite material with a certain proportion of a foaming agent or a foaming masterbatch and adding the mixture to a two-color injection molding machine, injecting the elastomer composite material with a second color after the PP skeleton is punched out, and injecting the molten elastomer material onto the PP skeleton. After the injection action is completed, the movable mold is set to retreat a certain amount to leave space for the elastomer composite material to foam and fill. The injection temperature is 180-220°C, the demolding distance is 0.2-1.5 times the thickness of the elastomer wall, the cooling time is 0.2-3min, and after cooling is completed, the mold is opened to take out the product.

[0026] Hydrogenated polystyrene-butadiene-polystyrene (SEBS) is a new type of styrene elastomer obtained by hydrogenating and saturating styrene-butylene-styrene (SBS). Due to the high saturation of the molecular chain, it has good temperature and heat resistance. In addition, SEBS has good compatibility with PP. Through a certain modification process, it is processed into a thermoplastic elastomer (TPE) with the characteristics of injection molding and foaming, and can be two-color injection molded with a PP skeleton. This type of TPE foam can directly be two-color injection molded with a PP skeleton to replace leather polyurethane foam coating products, which not only greatly improves production efficiency, but also facilitates later scrapping and recycling. TPE materials have very similar solubility parameters to PP and have certain compatibility. When recycling, they can be directly crushed and granulated without the need to separate soft and hard glue separately, which greatly improves the recycling efficiency of automotive products and reduces the difficulty of recycling.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The elastomer composite material for injection molding foaming and encapsulation of the present invention is prepared by a twin-screw composite modification process, and has the characteristics of excellent heat and weather resistance, high fluidity, strong mechanical properties, good foaming appearance, excellent encapsulation effect, and qualified automotive interior requirements such as odor and VOC;

[0029] (2) The production process of the elastomer composite material for injection molding foaming encapsulation of the present invention is two-color injection molding foaming integrated molding. Compared with the traditional coating process, the production steps are greatly simplified, and the molding cycle is reduced from the original 5-20min to 40-80s;

[0030] (3) Compared with the traditional two-color injection molding process, the injection molding and foaming process of the present invention has the characteristics of soft touch, excellent resilience, fine foaming, good appearance, firm rubber coating, and sound insulation and noise reduction;

[0031] (4) The plasticizer of the present invention is high-viscosity paraffin oil. Due to its high kinematic viscosity and flash point, it has less volatile matter, can maintain excellent elasticity at low temperatures, has low heat loss at high temperatures, has low haze value, and improves product production stability. It is particularly suitable for the strict odor and VOC requirements of automotive interior products.

[0032] (5) The present invention uses styrene elastomer as the base material. This material has good compatibility with PP toughened skeletons and PP reinforced skeletons for automobiles, and can be used for encapsulating PP hard skeletons or for injection molding foam products alone;

[0033] (6) The present invention adopts a process in which tert-butyl peroxide is mixed with a solvent and then injected separately at low temperature, which effectively solves the problems of easy volatility, flammability and explosion during the addition of peroxide, making its dosage more accurate and stable. DETAILED DESCRIPTION

[0034] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0035] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0036] When amount, concentration or other value or parameter is represented by range, preferred range or a series of upper preferred value and lower preferred value, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", the described range should be interpreted as including range "1 to 4", "1 to 3", "1-2", "1-2 and 4-5", "1-3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0037] "Polymer" means a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term "polymer" embraces the terms "homopolymer," "copolymer," "terpolymer," and "interpolymer."

[0038] Example 1

[0039] The invention discloses an elastomer composite material for injection molding foam encapsulation, which is prepared by a special twin-screw modification process. The raw materials of the composite elastomer are as follows by weight: 100 parts of styrene elastomer; 30 parts of special segment styrene elastomer; 40 parts of polyolefin elastomer; 80 parts of plasticizer; 10 parts of maleic anhydride graft; 2.5 parts of tert-butyl peroxide; 3 parts of foaming agent and 1 part of antioxidant and anti-ultraviolet additive.

[0040] Among them, the styrene elastomer is SEBS with a weight-average molecular weight of ≥200,000; the plasticizer is high-viscosity paraffin oil with a kinematic viscosity of 80 mm2 / s at 40°C, a flash point of 270°C, and a straight-chain hydrocarbon (CP) content of 65%; the special segment styrene elastomer has a styrene content of 30%, a butadiene content of 50%, a monomer styrene content of 20%, and a saturation of ≥99%; the polyolefin elastomer is eight-carbon POP with a melt index of ≥5g / 10min; the tert-butyl peroxide is a mixture of diisopropylbenzene peroxide (DCP) and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPMH) in a ratio of 1:1; the antioxidant and anti-ultraviolet agent is a mixture of 626, 1010, UV329, and UV770 in a ratio of 1:1:2:2; the foaming agent is sodium bicarbonate masterbatch with an effective content of 50%.

[0041] Wherein, the preparation method of maleic anhydride comprises the steps of:

[0042] (1.a) Extruding corresponding weight portions of styrene elastomer matrix, antioxidant and catalyst into masterbatch A through twin-screw extrusion, the rotation speed is 200-550r / min, and the temperature is 165-200°C;

[0043] (1.b) stirring and dissolving maleic anhydride monomer and crosslinking agent in corresponding weight parts at 10-30° C. to prepare sulfide liquid B, wherein the stirring speed is 20-80 r / min;

[0044] (1.c) Grafting reaction: Masterbatch A and sulfide liquid B are grafted and cross-linked in a twin screw to form maleic anhydride grafted material. The speed of the twin screw is 300-600 r / min and the reaction temperature is 160-205°C. Maleic anhydride grafted material particles are prepared by underwater pelletizing.

[0045] The maleic anhydride grafted material comprises 100 parts of styrene elastomer base (SEBS), 8 parts of maleic anhydride monomer, 0.5 parts of dicumyl peroxide (DCP), 0.2 parts of antioxidant (1076) and 0.2 parts of antioxidant (9228), and 0.1 parts of TiCl4 catalyst. The styrene elastomer base is characterized by a melt index of greater than 30g / 10min at 230°C*2.16kg, a weight average molecular weight of 55,000-60,000, and a styrene content of 20% in the molecular chain. Due to its small molecular weight, it has greater reactivity and is more likely to undergo grafting reaction with maleic anhydride monomer.

[0046] A method for preparing an elastomer composite material for injection molding foam encapsulation comprises the following steps:

[0047] (1) mixing corresponding weight portions of styrene elastomer matrix, special segment styrene elastomer, plasticizer, polyolefin elastomer, maleic anhydride grafted product, and antioxidant and anti-ultraviolet agent uniformly by a high-speed mixer or a coloring machine at a speed of 10 to 500 r / min and a temperature of 20 to 60° C.;

[0048] (2) injecting corresponding weight portions of tert-butyl peroxide through the reserved injection holes of the 2nd to 8th sections of the screw using a peristaltic pump, which is referred to as pump A; wherein the peristaltic pump speed is 5 to 50 r / min;

[0049] (3) The corresponding material ratio is achieved by adjusting the feeding speed of the twin-screw extruder and the speed of the A pump, wherein the twin-screw speed is 200-650r / min, the twin-screw temperature is 180-250°C, and the weight loss scale feeding is turned on when the screw reaches a specific speed, and the A pump is turned on after 1 minute. After underwater pelletizing, the elastomer composite material for injection molding foam encapsulation is obtained.

[0050] Wherein, the temperature of the coloring machine in step (1) is 25° C., the mixing speed is 100 rpm, the temperature of the tert-butyl peroxide in step (2) is 0° C., the speed of the A pump is 17 rpm, and the weight content is 2.5 parts.

[0051] An application method of an elastomer composite material for injection molding foaming and encapsulation as claimed in claim 1, characterized in that it comprises the steps of: uniformly mixing the prepared elastomer composite material with a certain proportion of a foaming agent or a foaming masterbatch and adding the mixture to a two-color injection molding machine; after the PP skeleton is punched out, injecting the elastomer composite material with a second color; injection molding the molten elastomer material on the PP skeleton; after the injection action is completed, the movable mold is set to retreat a certain amount to leave space for the elastomer composite material to foam and fill; the injection temperature is 180-220°C, the demolding distance is 0.2-1.5 times the thickness of the elastomer wall, the cooling time is 0.2-3min, and after cooling is completed, the mold is opened to take out the product.

[0052] Example 2-12

[0053] The preparation method and application method of Examples 2-12 are the same as those of Example 1, and the formula ratio is adjusted as shown in Table 1.

[0054] Table 1: Formula ratio of Examples 2-12

[0055]

[0056]

[0057] Comparative Example 1

[0058] The comparative example of an elastomer composite material for injection molding foaming encapsulation comprises the following raw materials in parts by weight: 100 parts of a styrene elastomer matrix; 60 parts of a plasticizer; 40 parts of polypropylene; 3 parts of a foaming agent and 1 part of an anti-oxidation and anti-ultraviolet additive.

[0059] Among them, the styrene elastomer is SEBS, the plasticizer is conventional viscosity paraffin oil, the kinematic viscosity at 40°C is 20-35mm2 / s, the content of straight chain hydrocarbon (CP) is greater than 65%, the polypropylene is copolymer polypropylene, the melt flow rate is 1-5g / 10min, the foaming agent is sodium bicarbonate masterbatch, and the effective content is 50%; the antioxidant and anti-ultraviolet additive is a mixture of 626, 1010, UV329, and UV770 in a ratio of 1:1:2:2.

[0060] A comparative preparation method of an elastomer composite material for injection molding foam encapsulation comprises the following steps:

[0061] A method for preparing an elastomer composite material for injection molding foam encapsulation comprises the following steps:

[0062] (1) mixing corresponding weight portions of styrene elastomer matrix, plasticizer, polypropylene, and antioxidant and anti-ultraviolet agent uniformly by a high-speed mixer or a coloring machine at a speed of 10 to 500 r / min and a temperature of 20 to 60° C.;

[0063] (2) Extrusion granulation is performed by a twin-screw extruder, the twin-screw speed is 200-650 r / min, and the twin-screw temperature is 180-250° C. After underwater pelletization, the elastic composite material for injection molding foam encapsulation is obtained.

[0064] Wherein, the temperature of the coloring machine in step (1) is 25° C., and the mixing speed is 100 rpm.

[0065] An application method of an elastomer composite material for injection molding foaming and encapsulation as claimed in claim 1, characterized in that it comprises the steps of: uniformly mixing the prepared elastomer composite material with a certain proportion of a foaming agent or a foaming masterbatch and adding the mixture to a two-color injection molding machine; after the PP skeleton is punched out, injecting the elastomer composite material with a second color; injection molding the molten elastomer material on the PP skeleton; after the injection action is completed, the movable mold is set to retreat a certain amount to leave space for the elastomer composite material to foam and fill; the injection temperature is 180-220°C, the demolding distance is 0.2-1.5 times the thickness of the elastomer wall, the cooling time is 0.2-3min, and after cooling is completed, the mold is opened to take out the product.

[0066] Comparative Example 2

[0067] The preparation method and application method of Comparative Example 2 are the same as those of Comparative Example 1, except that a special segment styrene elastomer raw material is added, wherein the amount of the special segment styrene elastomer is 30 parts.

[0068] Comparative Example 3

[0069] The preparation method and application method of Comparative Example 3 are the same as those of Comparative Example 2, except that a maleic anhydride grafted material is added, wherein the amount of the maleic anhydride grafted material is 5 parts.

[0070] Wherein, the preparation method of maleic anhydride comprises the steps of:

[0071] (1.a) Extruding corresponding weight portions of styrene elastomer matrix, antioxidant and catalyst into masterbatch A through twin-screw extrusion, the rotation speed is 200-550r / min, and the temperature is 165-200°C;

[0072] (1.b) stirring and dissolving maleic anhydride monomer and crosslinking agent in corresponding weight parts at 10-30° C. to prepare sulfide liquid B, wherein the stirring speed is 20-80 r / min;

[0073] (1.c) Grafting reaction: Masterbatch A and sulfide liquid B are grafted and cross-linked in a twin screw to form maleic anhydride grafted material. The speed of the twin screw is 300-600 r / min and the reaction temperature is 160-205°C. Maleic anhydride grafted material particles are prepared by underwater pelletizing.

[0074] Comparative Example 4

[0075] The preparation method and application method of Comparative Example 4 are the same as those of Comparative Example 3, except that tert-butyl peroxide raw material is added, wherein the amount of tert-butyl peroxide is 1 part.

[0076] Comparative Example 5

[0077] The preparation method and application method of Comparative Example 5 are the same as those of Comparative Example 4, except that the type of plasticizer is changed, wherein the plasticizer is replaced with high-viscosity paraffin oil, with a kinematic viscosity of 80 mm2 / s at 40°C, a flash point of 270°C, a straight-chain hydrocarbon (CP) content of 65%, and an amount of 60 parts of the high-viscosity plasticizer.

[0078] Comparative Example 6

[0079] The preparation method and application method of Comparative Example 6 are the same as those of Comparative Example 5, except that polypropylene is replaced with a polyolefin elastomer, wherein the polyolefin elastomer is an eight-carbon POP with a melt index ≥5g / 10min, and the amount of the polyolefin elastomer is 40 parts.

[0080] Performance Test:

[0081] The tensile strength at break is tested according to ISO37 standard, the strip is type 2, and the tensile speed is 500 mm / min. The tear strength is tested according to ISO34-1 standard, the strip is a right-angle tearing strip, and the tensile speed is 500 mm / min. The hardness is tested according to ISO868 standard, and the reading time is 15S. The cross scratch is tested according to PV3952 standard, the weight is 10N, and the scraper is 1mm. The melt index is tested according to ISO1133-1 standard, the test conditions are 190°C, the weight is 2.16kg, and the foaming density is tested according to ISO 1183-1 standard. Four samples of the material are tested and the average value is taken. The performance test results of Examples 1 to 12 are shown in Table 2.

[0082] Table 2 Performance test results of Examples 1 to 12

[0083]

[0084] The performance test results of Comparative Examples 1 to 6 are shown in Table 3.

[0085]

[0086]

[0087] Table 3 Performance test results of comparative examples 1 to 6

[0088] From the performance comparison of the above-mentioned embodiments 1 to 4 and comparative examples 1 and 2, it can be seen that the present invention significantly increases the scratch resistance of the material by adding the special segmented styrene elastomer, and the cross scratch performance can be increased from the original 1.9 to 0.6 at the highest. As the addition of the special segmented styrene gradually increases, the scratch resistance gradually stabilizes, but after adding too much, the hardness of the material increases, the feel becomes worse, and the elongation performance decreases. From the performance comparison of the above-mentioned embodiments 1, 3, 5, 6 and comparative examples 1 and 6, it can be seen that the addition of polyolefin elastomer improves the feel and foaming performance of the material. As the amount of polyolefin elastomer increases, the hardness of the composite material gradually decreases. Compared with polypropylene, the hardness decreases more significantly, and the foaming characteristics are significantly improved. The density is reduced from 0.85g / 10min to 0.65g / 10min at the highest. However, after the polyolefin elastomer is further increased, The mechanical properties of the composite material are significantly reduced, and the scratch resistance is deteriorated; from the performance comparison of the above-mentioned Examples 1, 5, 7, 8 and Comparative Examples 1, 5, it can be seen that the addition of high-viscosity plasticizer significantly improves the hardness and feel of the material, but as the amount of addition increases, the scratch and mechanical properties of the composite material decrease accordingly; from the performance comparison of the above-mentioned Examples 1, 7, 9, 10 and Comparative Examples 1, 3, it can be seen that maleic anhydride grafts can significantly increase the scratch resistance and mechanical properties of the material, but excessive addition of maleic anhydride grafts can cause the feel and odor of the material to be significantly reduced; from the performance comparison of the above-mentioned Examples 1, 9, 11, 12 and Comparative Examples 1, 4, it can be seen that tert-butyl peroxide improves the fluidity of the material, improves the processing characteristics of the material, and improves the foaming characteristics of the material, but as more tert-butyl peroxide is added, the effect on the fluidity of the material is very obvious, which increases the difficulty of material molding and the airtightness of the pores after foaming.The elastomeric composite material for injection molding, foaming and encapsulation of the present invention is prepared by a twin-screw composite modification process, and has the characteristics of excellent heat and weather resistance, high fluidity, strong mechanical properties, good foaming appearance, excellent encapsulation effect, and qualified automotive interior requirements such as odor and VOC; the elastomeric composite material for injection molding, foaming and encapsulation of the present invention has a production process of two-color injection molding, foaming and integrated molding. Compared with the traditional coating process, the production steps are greatly simplified, and the molding cycle is reduced from the original 5-20 minutes to 40-80 seconds; compared with the traditional two-color injection molding process, the injection molding and foaming process of the present invention has the characteristics of soft hand feeling, excellent resilience, fine foaming, good appearance, firm encapsulation, and sound insulation and noise reduction; the plasticizer of the present invention High-viscosity paraffin oil is selected. Due to its high kinematic viscosity and flash point, it has less volatile substances, can maintain excellent elasticity at low temperatures, has small heat loss at high temperatures, has low haze value, and improves product production stability, and is particularly suitable for strict odor and VOC requirements of automotive interior products. The present invention adopts styrene elastomer as a base material, and this material has good compatibility with automotive PP toughened skeletons, PP reinforced skeletons, etc., and can be used for encapsulating PP hard skeletons or for injection molding foam products alone. The present invention adopts a process in which tert-butyl peroxide is mixed with a solvent and then injected alone at low temperature, which effectively solves the problems of easy volatilization, flammability and explosion during the addition of peroxide, and makes the dosage more accurate and stable.

[0089] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. An elastomer composite material for injection molding foam encapsulation, characterized in that: The raw materials include, by weight: 100 parts of hydrogenated styrene elastomer matrix; 10-50 parts of special segment styrene elastomer; 20-60 parts of polyolefin elastomer; 50-100 parts of plasticizer; 2-20 parts of maleic anhydride graft; 1-5 parts of tert-butyl peroxide; 0.5-10 parts of foaming agent; and 0.5-5 parts of antioxidant and anti-ultraviolet additive.

2. The elastic composite material for injection molding foaming and encapsulation according to claim 1, characterized in that: The raw materials include, by weight: 100 parts of hydrogenated styrene elastomer matrix; 20 parts of special segment styrene elastomer; 30 parts of polyolefin elastomer; 80 parts of plasticizer; 10 parts of maleic anhydride graft; 2 parts of tert-butyl peroxide and 3 parts of antioxidant and anti-ultraviolet additive.

3. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The hydrogenated styrene elastomer matrix is ​​selected from one or a combination of SEBS (hydrogenated styrene-butadiene-styrene triblock copolymer), SEPS (hydrogenated styrene-isoprene-styrene triblock copolymer), SEEPS (hydrogenated styrene-ethylene-isoprene-styrene block copolymer).

4. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The special segment styrene elastomer has the following characteristics: the styrene block content at both ends is 20-40%; the middle butadiene segment contains special monomers, the monomer accounts for 10-30%, and the monomer is selected from one or more of ethylene, ethylene norbornene, propylene, styrene, acrylonitrile, tetrahydrofuran, and polyols.

5. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The polyolefin elastic elastomer is selected from one of POP, EPDM, OBC and POE or a combination of several of them.

6. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The raw materials for preparing the maleic anhydride grafted material include: 100 parts of styrene elastomer, 1 to 10 parts of maleic anhydride monomer, 0.15 to 0.8 parts of dicumyl peroxide (DCP), 0.01 to 0.08 parts of antioxidant (1076) and 0.01 to 0.08 parts of antioxidant (9228), and 0.01 to 0.3 parts of TiCl4 catalyst.

7. The elastic composite material for injection molding foaming and encapsulation according to claim 6, characterized in that: The method for preparing the maleic anhydride grafted material comprises the following steps: S410: Extruding and granulating the corresponding weight portions of styrene elastomer matrix, antioxidant and catalyst through a twin-screw extruder at a speed of 200 to 550 r / min and a temperature of 165 to 200° C. to prepare masterbatch A; S420: stirring and dissolving maleic anhydride monomer and crosslinking agent in corresponding weight parts at 10-30° C. to prepare sulfide liquid B, wherein the stirring speed is 20-80 r / min; S430 grafting reaction, master batch A, sulfide liquid B, graft cross-linking in a twin screw to form maleic anhydride grafted material, the speed of the twin screw is 300-600r / min, the reaction temperature is 160-205°C, and maleic anhydride grafted material particles are formed by underwater pelletizing.

8. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The plasticizer is high-viscosity paraffin oil, the kinematic viscosity of the paraffin oil at 40° C. is not less than 60 mm 2 / s, the flash point is not less than 270° C., and the CP value is greater than 65%.

9. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The tert-butyl peroxide is selected from one or more of diisopropylbenzene peroxide (DCP), 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (BPMC), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPMH), and 1,3-bis(tert-butylperoxyisopropyl)benzene (BIPB).

10. The elastic composite material for injection molding foaming and encapsulation according to claim 1 or 2, characterized in that: The foaming agent is selected from one or more of sodium bicarbonate, sodium bicarbonate foaming masterbatch, azodicarbonamide, AC foaming masterbatch, and microsphere foaming masterbatch.

11. An elastomer composite material for injection molding foaming encapsulation according to claim 1 or 2, characterized in that: According to one embodiment of the present invention, the antioxidant and anti-ultraviolet agent are selected from one or more of 1010, 1076, 1330, 1024, 168, 626, DLTDP, UV531, UV326, UV328, UV329, UV234, UV770, UV944, and UV622.

12. The method for preparing the elastic composite material for injection molding foaming encapsulation according to claim 1 or 2, characterized in that: It includes the steps of: S100: Evenly mix the corresponding weight portions of styrene elastomer matrix, special segment styrene elastomer, plasticizer, polyolefin elastomer, maleic anhydride grafted material, and antioxidant and anti-ultraviolet agent through a high-speed mixer or a coloring machine; S200 uses a peristaltic pump to inject the corresponding weight portion of tert-butyl peroxide through the reserved injection holes in the 2nd to 8th sections of the screw, which is called pump A.

13. The method for preparing the elastic composite material for injection molding foaming and encapsulation according to claim 12, characterized in that: The temperature of the coloring machine in step S100 is 20-60° C., the mixing speed is 10-500 r / min, the temperature of the tert-butyl peroxide in step S200 is 0-10° C., and the speed of the A pump is 5-50 r / min.

14. The method for preparing the elastic composite material for injection molding foaming encapsulation according to claim 12, characterized in that: The tert-butyl peroxide used in step S200 is volatile and flammable, so the peroxide is mixed with mineral oil in a ratio of 1:2 and then placed in a refrigerator for cooling before use. The refrigerator temperature is set to 0°C.

15. The method for preparing the elastic composite material for injection molding foaming encapsulation according to claim 12, characterized in that: The method also includes the following steps: S300 adjusts the feeding speed of the twin-screw extruder and the speed of the A pump to achieve the corresponding material ratio, wherein the twin-screw speed is 200-650r / min, the twin-screw temperature is 180-250°C, and the weight loss scale feeding is started first when the screw reaches a specific speed, and the A pump is started after 1 minute; and the elastomer composite material for injection molding foaming is obtained through underwater pelletizing.

16. An application method of an elastomer composite material for injection molding foaming and encapsulation as described in claim 1 or 2, comprising the following steps: mixing the prepared elastomer composite material with a certain proportion of a foaming agent or a foaming masterbatch and adding the mixture into a two-color injection molding machine; after the PP skeleton is punched out, injecting the elastomer composite material with the second color; injection molding the molten elastomer material onto the PP skeleton; after the injection action is completed, the movable mold is set to retreat a certain amount to leave space for the elastomer composite material to foam and fill; the injection temperature is 180-220°C, the demolding distance is 0.2-1.5 times the thickness of the elastomer wall, the cooling time is 0.2-3min, and after cooling, the mold is opened to take out the product.

Images