A transparent TPE material encapsulated with POM, its preparation method and application

Abstract

The present invention discloses a transparent POM-encapsulated TPE material and its preparation method, belonging to the technical field of thermoplastic elastomers. The present invention utilizes a low-molecular-weight, low-styrene-content styrene-based elastomer A, a silane-grafted styrene elastomer B, and an acrylate block copolymer to produce a POM-encapsulated transparent TPE material that combines high transparency, excellent bonding properties, and good processing properties. The resulting POM-encapsulated transparent TPE material is suitable for use in the manufacture of automotive and power tool parts, and has promising market application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoplastic elastomers, and in particular relates to a transparent TPE material encapsulating POM, a preparation method thereof, and an application thereof. Background Art

[0002] Polyoxymethylene (POM) is a linear polymer with no side chains, high density, and high crystallinity. It possesses excellent physical, mechanical, and chemical properties, particularly superior friction resistance. Commonly known as "Saigang" or "Dugang," POM is the third most common engineering plastic and is suitable for manufacturing wear-resistant and anti-friction parts, transmission components, chemical components, and instrumentation components.

[0003] POM encapsulation combines the toughness and impact resistance of POM with the flexibility of thermoplastic elastomers, giving the rigid POM substrate a soft feel and providing noise reduction, vibration damping, collision protection, and anti-slip properties. However, due to its high crystallinity and extremely low surface friction coefficient, POM is the most difficult hard plastic to encapsulate in the industry, and encapsulating POM presents significant technical challenges.

[0004] Currently, TPE materials used for encapsulating rigid plastics on the market are primarily based on hydrogenated poly(styrene-b-butadiene-b-styrene) (SEBS), extender oil, and filler. Depending on performance requirements, polypropylene, polyethylene, or thermoplastic polyurethane elastomers may be added. These TPE materials often offer excellent encapsulation for general-purpose plastics, but their effectiveness for encapsulating POM is less than ideal. They exhibit low fluidity, poor processability, poor adhesion, and easy peeling.

[0005] In addition, when used in industries with high requirements for aesthetics, such as automobiles and home appliances, POM products are best to have a certain degree of transparency. However, given the difficulty of encapsulating POM, balancing the adhesion and transparency of encapsulated POM products remains a major challenge in this field.

[0006] Therefore, the development of a transparent TPE material encapsulating POM with high transparency, excellent bonding properties and good processing properties has important research significance and application value. Summary of the Invention

[0007] To address the technical problem of existing POM-encapsulated TPE materials, which struggle to achieve high transparency, excellent bonding properties, and good processing properties, the present invention primarily aims to provide a transparent POM-encapsulated TPE material. The TPE material provided herein utilizes a low-molecular-weight, low-styrene-content styrene elastomer (A) modified with a silane-grafted styrene elastomer (B) and an acrylate block copolymer. This results in a POM-encapsulated transparent TPE material that combines high transparency, excellent bonding properties, and good processing properties.

[0008] Another object of the present invention is to provide a method for preparing the transparent TPE material encapsulated with POM.

[0009] Another object of the present invention is to provide an application of the transparent TPE material encapsulated with POM in the field of preparing automotive parts and power tool parts.

[0010] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0011] A transparent TPE material encapsulated with POM, comprising the following components in parts by weight: 20-30 parts of styrene elastomer A, 10-20 parts of styrene elastomer B, 10-20 parts of acrylic block copolymer, and 20-40 parts of filler oil;

[0012] Wherein, the styrene elastomer A is hydrogenated poly(styrene-b-butadiene-b-styrene);

[0013] The styrene elastomer B is silane-grafted hydrogenated poly(styrene-b-butadiene-b-styrene);

[0014] The weight average molecular weight of the styrene elastomer A is 30,000 to 100,000 and the styrene content is 10% to 20%;

[0015] The weight average molecular weight of the styrene elastomer B is ≥100,000 and the styrene content is 28-32%.

[0016] The present invention provides a transparent TPE material encapsulated with POM. The material utilizes hydrogenated poly(styrene-b-butadiene-b-styrene) with a low molecular weight and low styrene content, which exhibits excellent fluidity and imparts good transparency and fluidity to the TPE material. The addition of silane-grafted hydrogenated poly(styrene-b-butadiene-b-styrene) imparts adhesion and moderate mechanical properties to the TPE material. An acrylate block copolymer can be used in conjunction with the silane-grafted hydrogenated poly(styrene-b-butadiene-b-styrene) to synergistically enhance POM adhesion and, in conjunction with the hydrogenated poly(styrene-b-butadiene-b-styrene), to synergistically enhance transparency. The silane-grafted hydrogenated poly(styrene-b-butadiene-b-styrene) must have a high molecular weight and high styrene content to ensure adequate mixing with the filler oil. Insufficient mixing can result in poor fluidity of the TPE material, ultimately affecting adhesion.

[0017] The method for determining the weight average molecular weight of the present invention refers to GB / T 27843-2011, tetrahydrofuran is used as the solvent, and a THF type chromatographic column is used as the chromatographic column; the styrene content is determined by nuclear magnetic resonance.

[0018] Preferably, the mass percentage of the styrene elastomer A in the composition is not less than 24.5%.

[0019] Specifically, the styrene-based elastomer B is obtained by melt grafting hydrogenated poly(styrene-b-butadiene-b-styrene) with silane.

[0020] Preferably, the silane grafting rate of the styrene elastomer B is 0.1 to 2 wt%, preferably 0.5 to 0.8 wt%.

[0021] Specifically, the silane is a silane coupling agent containing a carbon-carbon double bond or a carbon-carbon triple bond, and is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane.

[0022] Preferably, the acrylic ester block copolymer is selected from at least one of a methyl methacrylate-acrylic esters-methyl methacrylate block copolymer and an ethylene-butyl acrylate copolymer.

[0023] Specifically, the methyl methacrylate-acrylic esters-methyl methacrylate block copolymer is selected from at least one of methyl methacrylate-methyl acrylate-methyl methacrylate block copolymer, methyl methacrylate-ethyl acrylate-methyl methacrylate block copolymer, methyl methacrylate-propyl acrylate-methyl methacrylate block copolymer or methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer.

[0024] Preferably, the TPE material further comprises an antioxidant and / or an amide lubricant, specifically 0.1-1 parts of the antioxidant and 0-2 parts of the amide lubricant.

[0025] In order to ensure the transparency of the TPE material, the present invention selects amide lubricants.

[0026] Preferably, the amide lubricant is selected from at least one of erucamide and oleamide.

[0027] Preferably, the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 168, preferably a compound antioxidant of the two, and preferably the mass ratio of antioxidant 1010 to antioxidant 168 is 1:2 to 1:5.

[0028] Specifically, the filler oil is white oil. More specifically, the kinematic viscosity of the white oil is 90 to 100 mm 2 / s, open flash point ≥260℃.

[0029] The present invention also provides a method for preparing a transparent TPE material encapsulated with POM, comprising the following steps:

[0030] The filler oil is pre-mixed with the styrene elastomer B at a low speed, and then mixed with the styrene elastomer A, the acrylic block copolymer and other additives at a high speed; the mixed raw materials are melt-extruded, cooled and granulated to obtain the transparent TPE material encapsulated with POM.

[0031] Preferably, the melt extrusion conditions are: melt extrusion temperature of 170-180° C., extrusion residence time of 50-80 s, moisture content ≤0.5%, aspect ratio of the twin-screw extruder of 40-56:1, and screw speed of 200-300 rpm.

[0032] The melt extrusion process requires strict control of moisture.

[0033] The application of the transparent TPE material coated with POM in the preparation of automotive parts or power tool parts also falls within the protection scope of the present invention.

[0034] Preferably, the transparent TPE material encapsulating POM is used in the preparation of automotive seals, automotive shock absorbers or handle protective covers of electric tools.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The transparent TPE material for encapsulating POM provided by the present invention selects low-molecular-weight, low-styrene-content SEBS to maintain good processing performance and transparency; silane-grafted styrene elastomer and acrylate block copolymer are used to collaboratively improve the performance of bonding to POM. The obtained transparent TPE material for encapsulating POM has the advantages of high transparency, excellent bonding performance and good processing performance. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

[0038] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0039] The styrene content and weight-average molecular weight of the following hydrogenated poly(styrene-b-butadiene-b-styrene) are self-measured values, and the determination method is as follows:

[0040] Styrene content determination method: NMR;

[0041] The method for determining the weight average molecular weight is as follows: GB / T 27843-2011, the solvent is tetrahydrofuran, and the chromatographic column is a THF type column.

[0042] SEBS-A 1#: Hydrogenated poly(styrene-b-butadiene-b-styrene), brand G1657, manufacturer Kraton, styrene content of 14%, weight-average molecular weight of 60,000;

[0043] SEBS-A 2#: Hydrogenated poly (styrene-b-butadiene-b-styrene), brand YH-510, manufacturer Yuehua, styrene content is 20%, weight average molecular weight is 80,000;

[0044] SEBS-A 3#: Hydrogenated poly(styrene-b-butadiene-b-styrene), brand MD1646, manufacturer Kraton, styrene content of 13%, weight-average molecular weight of 50,000;

[0045] SEBS-A 4#: Hydrogenated poly (styrene-b-butadiene-b-styrene), brand YH-506, manufacturer Yuehua, styrene content of 13%, weight-average molecular weight of 150,000;

[0046] SEBS-A 5#: hydrogenated poly(styrene-b-butadiene-b-styrene), brand G1642, manufacturer Kraton, styrene content of 22.5%, weight-average molecular weight of 100,000;

[0047] SEBS-B 1#: Hydrogenated poly(styrene-b-butadiene-b-styrene): G1654, manufactured by Kraton; styrene content 30%, weight-average molecular weight 150,000; Silane grafting: vinyltriethoxysilane, SICO-V151, manufactured by SICO New Materials; grafting ratio 0.6 wt%;

[0048] SEBS-B 2#: Hydrogenated poly(styrene-b-butadiene-b-styrene): brand YH-688, manufactured by Yuehua; styrene content 15%, weight-average molecular weight 180,000; silane grafting: vinyltriethoxysilane, brand SICO-V151, manufactured by SICO New Materials; silane grafting rate 0.6wt%;

[0049] SEBS-B 3#: Hydrogenated poly(styrene-b-butadiene-b-styrene): brand A1536HS, manufacturer Kraton; styrene content 40%, weight-average molecular weight 150,000; silane grafting: vinyltriethoxysilane, SICO-V151, SICO New Materials; silane grafting rate 0.6wt%;

[0050] SEBS-B 4#: Hydrogenated poly(styrene-b-butadiene-b-styrene): brand G1654, manufacturer Kraton, styrene content 30%, weight-average molecular weight 150,000, ungrafted;

[0051] SEBS-B 5#: Hydrogenated poly(styrene-b-butadiene-b-styrene): brand G1654, manufacturer Kraton; styrene content 30%, weight-average molecular weight 150,000; maleic anhydride grafted; maleic anhydride grafting ratio 0.6wt%;

[0052] SEBS-B 6#: Hydrogenated poly(styrene-b-butadiene-b-styrene): G1652, manufactured by Kraton; styrene content 30%, weight-average molecular weight 80,000; Silane grafting: vinyltriethoxysilane, SICO-V151, SICO New Materials; silane grafting rate 0.6 wt%;

[0053] Acrylate block copolymer 1#: methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer, KURARITY™ LA4285, Kuraray;

[0054] Acrylate block copolymer 2#: ethylene-butyl acrylate copolymer (EBA), EBAREPSOL E1704, Lepsol, Spain;

[0055] Filling oil: white oil, PW-90, Idemitsu, Japan;

[0056] Lubricant: erucamide lubricant, commercially available;

[0057] Antioxidants: antioxidant 1010, antioxidant 168, commercially available; the mass ratio of antioxidant 1010 to antioxidant 168 is 1:3.

[0058] SEBS-B 1# to SEBS-B 3# are prepared by the following process:

[0059] In the premixing section of the extruder, the components were uniformly mixed according to the ratio of 15 mmol of silane / 15 mmol of diisopropylbenzene peroxide / 100 g of hydrogenated poly(styrene-b-butadiene-b-styrene), and then fed into a twin-screw extruder for melt grafting at an extrusion temperature of 190°C and a rotation speed of 200 rpm.

[0060] SEBS-B 5# is prepared by the following process:

[0061] In the premixing section of the extruder, a certain amount of maleic anhydride, 15 mmol of diisopropylbenzene peroxide, 100 g of hydrogenated poly(styrene-b-butadiene-b-styrene) and other components were uniformly mixed and put into a twin-screw machine for melt grafting. The extrusion temperature was 190°C and the speed was 200 rpm.

[0062] The transparent TPE materials encapsulated with POM in the embodiments and comparative examples of the present invention were prepared by the following process:

[0063] The white oil is pre-mixed with the styrene elastomer B at a low speed, and then mixed with the styrene elastomer A, the acrylic block copolymer, the filler and other additives in a high-speed mixer at a high speed; the mixed raw materials are added to a twin-screw extruder, melt-extruded, and then cooled and granulated to obtain the transparent TPE material encapsulated with POM;

[0064] The melt extrusion conditions of the twin-screw extruder are as follows: the raw material is dried at 80°C for 12 hours, the moisture content is ≤0.5%, the melt extrusion temperature is 200°C, the residence time of the extrusion process is 80 seconds, the aspect ratio of the twin-screw extruder is 40:1, and the screw speed is 300 rpm.

[0065] Comparative Example 6: White oil was pre-mixed with SEBS-B 4# at a low speed, and then mixed with vinyl triethoxysilane, dicumyl peroxide, styrene elastomer A, acrylate block copolymer, filler, and other additives at a high speed in a high-speed mixer; the mixed raw materials were added to a twin-screw extruder, melt-extruded, and then cooled and granulated to obtain the transparent TPE material encapsulated with POM, wherein the addition ratio of vinyl triethoxysilane and dicumyl peroxide was 15 mmol of silane / 15 mmol of dicumyl peroxide / 100 g of SEBS-B 4#;

[0066] The melt extrusion conditions of the twin-screw extruder are as follows: the raw material is dried at 80°C for 12 hours, the moisture content is ≤0.5%, the melt extrusion temperature is 200°C, the residence time of the extrusion process is 80 seconds, the aspect ratio of the twin-screw extruder is 40:1, and the screw speed is 300 rpm.

[0067] Comparative Example 7: White oil was pre-mixed with SEBS-B 5# at a low speed, and then mixed with styrene elastomer A, acrylic block copolymer, filler, and other additives in a high-speed mixer at a high speed; the mixed raw materials were added to a twin-screw extruder, melt-extruded, and then cooled and granulated to obtain the transparent TPE material encapsulated with POM;

[0068] The melt extrusion conditions of the twin-screw extruder are as follows: the raw material is dried at 80°C for 12 hours, the moisture content is ≤0.5%, the melt extrusion temperature is 200°C, the residence time of the extrusion process is 80 seconds, the aspect ratio of the twin-screw extruder is 40:1, and the screw speed is 300 rpm.

[0069] The performance testing methods and standards of the transparent TPE materials of the embodiments and comparative examples of the present invention are as follows:

[0070] The particle material prepared according to the above method was dried in a forced air oven at 75° C. for 3 hours, and then the dried particles were made into standard specimens on an injection molding machine for testing.

[0071] (1) Shore hardness (A): Refer to ISO 7619-2012 standard, where the reading time is 15 seconds.

[0072] (2) Peel force (N / mm): Refer to VDI 2019 standard, where the soft adhesive thickness is 2.0 mm.

[0073] (3) Transparency: Refer to GB / T 2410-2008 standard, where the thickness is 2.0 mm.

[0074] (4) Melt index MI (g / 10 min): refer to ISO 1133-2011 standard, where the test conditions are 230°C / 2.16 kg.

[0075] Examples 1 to 11

[0076] This embodiment provides a series of transparent TPE materials encapsulated with POM, and the weight percentages of the components in the formulas are shown in Tables 1 and 2.

[0077] Table 1 Examples 1 to 3 formulations (parts)

[0078]

[0079] Table 2 Examples 3 to 11 formulations (parts)

[0080]

[0081] Comparative Examples 1 to 10

[0082] This comparative example provides a series of transparent TPE materials encapsulated with POM, and the components in the formula are shown in Table 3.

[0083] Table 3 Formulas of Comparative Examples 1 to 10 (parts)

[0084]

[0085] The performance test results of the transparent TPE material encapsulated with POM in each embodiment and comparative example according to the above-mentioned method are shown in Table 4.

[0086] Table 4 Performance test results of various embodiments and comparative examples

[0087]

[0088]

[0089] As can be seen from Table 4, the transparent TPE materials encapsulating POM prepared in Examples 1 to 11 of the present invention all have the characteristics of high transparency, excellent adhesion and good processing performance, wherein the transparency is higher than 65%, the peel force is higher than 2 N / mm, the melt flow rate is higher than 9 g / 10 min, and the hardness is 40 to 70A.

[0090] The weight average molecular weight of the styrene elastomer A used in Comparative Example 1 is too high and its fluidity is poor, which, on the one hand, leads to poor fluidity of the TPE material, thereby reducing the peeling force, and on the other hand, leads to reduced transparency of the TPE material; the styrene content of the styrene elastomer A used in Comparative Example 2 is too high, resulting in poor transparency; in Comparative Example 3, no styrene elastomer A is added, and the fluidity of the TPE material is very poor, resulting in all the performances of the TPE material not meeting expectations; in Comparative Example 4, no styrene elastomer B is added to provide the main body adhesion of the TPE material, and the peeling force of the TPE material is basically zero; in Comparative Example 5, no acrylic block copolymer is added, and on the one hand, the styrene elastomer B lacks the synergistic effect of adhesion, resulting in low adhesion of the TPE material, and on the other hand, the styrene elastomer A lacks the synergistic effect of transparency, resulting in low transparency of the TPE material; Instead of adding silane-grafted styrene elastomer B, ungrafted styrene elastomer B, silane and other components are directly blended during the preparation of the TPE material. Silane and ungrafted styrene elastomer B cannot be effectively grafted, resulting in almost no adhesion between the TPE material and POM and a peeling force of basically zero; Comparative Example 7 adds maleic anhydride-grafted styrene elastomer B, which has no adhesion to POM, resulting in a TPE material with a peeling force of basically zero; the styrene content of the styrene elastomer B added in Comparative Example 8 is too low, resulting in the styrene elastomer B being unable to absorb the filler oil and the TPE material being unable to be molded; the styrene content of the styrene elastomer B added in Comparative Example 9 is too high, resulting in low transparency of the TPE material; the weight-average molecular weight and mechanical strength of the styrene elastomer B added in Comparative Example 10 are too low, resulting in a low peeling force of the TPE material.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A transparent TPE material encapsulated with POM, characterized in that: The invention comprises the following components in parts by weight: 20-30 parts of styrene elastomer A, 10-20 parts of styrene elastomer B, 10-20 parts of acrylic block copolymer, and 20-40 parts of filler oil; Wherein, the styrene elastomer A is hydrogenated poly(styrene-b-butadiene-b-styrene); The styrene elastomer B is silane-grafted hydrogenated poly(styrene-b-butadiene-b-styrene); The weight average molecular weight of the styrene elastomer A is 30,000 to 80,000, and the styrene content is 10% to 20%; The weight average molecular weight of the styrene elastomer B is ≥100,000 and the styrene content is 28-32%; the acrylic ester block copolymer is selected from at least one of methyl methacrylate-acrylic ester-methyl methacrylate block copolymer or ethylene-butyl acrylate copolymer.

2. The transparent TPE material encapsulated with POM according to claim 1, characterized in that: The styrene elastomer B is obtained by melt grafting hydrogenated poly(styrene-b-butadiene-b-styrene) with silane.

3. The transparent TPE material encapsulated with POM according to claim 1 or 2, characterized in that: The silane grafting rate of the styrene elastomer B is 0.5-0.8 wt %.

4. The transparent TPE material encapsulated with POM according to claim 1 or 2, characterized in that: The silane is a silane coupling agent containing a carbon-carbon double bond or a carbon-carbon triple bond.

5. The transparent TPE material encapsulated with POM according to claim 1, characterized in that: The methyl methacrylate-acrylic ester-methyl methacrylate block copolymer is selected from at least one of methyl methacrylate-methyl acrylate-methyl methacrylate block copolymer, methyl methacrylate-ethyl acrylate-methyl methacrylate block copolymer, methyl methacrylate-propyl acrylate-methyl methacrylate block copolymer, and methyl methacrylate-butyl acrylate-methyl methacrylate block copolymer.

6. The transparent TPE material encapsulated with POM according to claim 1, characterized in that: The filler oil is white oil.

7. The transparent TPE material encapsulated with POM according to claim 1, characterized in that: The transparent TPE material further includes an antioxidant and / or an amide lubricant.

8. The method for preparing the transparent TPE material encapsulated with POM according to any one of claims 1 to 7, characterized in that: The following steps are involved: The filler oil is pre-mixed with the styrene elastomer B at a low speed; then mixed with the styrene elastomer A, the acrylic block copolymer, the filler and other additives at a high speed; the mixed raw materials are melt-extruded, cooled and granulated to obtain the transparent TPE material encapsulated with POM.

9. Use of the transparent TPE material encapsulated with POM according to any one of claims 1 to 7 in the preparation of automotive parts or power tool parts.

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