A pp composition, its preparation and use

Abstract

This invention discloses a PP composition, its preparation method, and its applications, relating to the field of polymer material modification technology. The PP composition provided by this invention comprises the following components in parts by weight: 90-97 parts PP resin, 0.4-2 parts PS resin, 0.1-1 parts compatibilizer, 0.1-1 parts laser-sensitive composite, and 2-10 parts white pigment; the laser-sensitive composite comprises ammonium molybdate and antimony tin oxide. Based on the easily carbon-forming PS resin and the introduction of ammonium molybdate and antimony tin oxide, this invention can enhance the laser marking effect of the PP composition through different principles, while ensuring the high mechanical properties of the PP material are maintained, thus improving the contrast of black marks made by laser on white PP compositions.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification technology, specifically to a PP composition, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) is widely used in daily necessities, packaging, medical devices, and automotive parts due to its low cost, good mechanical properties, and non-toxicity. In its specific applications, for classification and differentiation, it is often necessary to mark the PP surface with information such as production date and batch number using infrared laser (e.g., 1064 nm laser). To improve the contrast of the markings, the mainstream strategies currently used are "white background with black label," "black background with white label," and "black background with colored label." However, pure white PP material has extremely low absorption of infrared lasers, and direct marking usually only produces light-colored, low-contrast marks with very low clarity, failing to achieve the high-contrast effect of "white material with black label."

[0003] Currently, the industry mainly improves the contrast of laser marking by adding laser-sensitive additives (such as metal oxides and carbonates) to pure white PP substrates. However, this technology has many problems: 1) The amount of additives added is relatively large (usually 2-5%) and they are prone to uneven dispersion and precipitation, which affects the mechanical properties of the substrate, such as increased brittleness and decreased toughness; 2) The marking contrast is insufficient or the color is grayish instead of pure black. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a PP composition in which a small amount of easily carbonized PS polymer is introduced into the PP matrix, enhancing the PP's sensitivity to lasers. Furthermore, ammonium molybdate and antimony tin oxide are introduced, which can absorb more energy or undergo chemical reactions themselves, thereby further enhancing the laser marking effect of the PP composition while maintaining the high mechanical properties of the PP material.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A PP composition comprising the following components in parts by weight: 90-97 parts PP resin, 0.4-2 parts PS resin, 0.1-1 parts compatibilizer, 0.1-1 parts laser-sensitive composite, 2-10 parts white pigment; The laser-sensitive composite comprises ammonium molybdate and antimony tin oxide.

[0006] The principle of laser marking imaging is to use a laser to heat and carbonize a specific area on the surface of a material to form the desired mark. However, PP material is a non-carbon-forming polymer, so it is not easy to form a clear mark during laser marking, especially on a white PP substrate. Pure white PP material has extremely low absorption of infrared laser, further affecting the marking effect. The PP composition provided by this invention introduces a small amount of easily carbon-forming PS polymer into the PP substrate. By uniformly dispersing PS in the PP substrate, the possibility of carbonization of the PP substrate can be increased, thereby enhancing its sensitivity to laser. Based on this, this invention introduces a laser-sensitive composite compound, which enhances the laser marking effect while ensuring the mechanical properties of the PP substrate after marking through two pathways: 1. The laser-sensitive composite compound can absorb more energy, improving the carbonization of PP itself; 2. The laser-sensitive composite compound can also undergo a chemical reaction after absorbing infrared energy, generating a black compound. By introducing PS and the laser-sensitive composite compound, this invention can improve the effect of laser marking black marks on a white PP substrate while ensuring the mechanical properties of the PP material after marking.

[0007] It should be noted that the laser-sensitive composite in this application requires a specific combination of substances to achieve both high mechanical properties and contrast in the resulting PP composition. Ammonium molybdate, an inorganic salt, is commonly used as a "laser-sensitive additive." While it has weak absorption of infrared lasers, its ability to improve the laser sensitivity of the matrix stems from a thermochemical reaction. Under the high temperature of the laser, ammonium molybdate decomposes into molybdenum trioxide or other molybdenum oxide compounds. The newly formed molybdenum oxide compounds are typically dark in color, either dark gray or black, thus improving the marking effect. However, relying solely on the dark color provided by molybdenum oxide compounds offers very limited improvement to the black marking effect on white PP substrates. Therefore, this application also requires the introduction of antimony tin oxide, which enhances the carbonization effect of the PP / PS composite matrix itself. Antimony tin oxide (ATO) is an N-type semiconductor material with strong absorption characteristics and excellent photothermal conversion capabilities for infrared light. The charge carriers (electrons) in ATO undergo plasmon resonance in the infrared band, resulting in a very high absorption rate for near-infrared lasers such as 1064nm. When infrared lasers irradiate materials containing ATO, the ATO particles rapidly and efficiently convert light energy into heat energy, ablating and carbonizing PS to form markings. However, while the ablation and carbonization of PS improves the laser marking effect, it also significantly increases the brittleness of the marked material, affecting its mechanical properties. Therefore, this invention requires the combined use of two compounds to reinforce the material, achieving optimal laser marking results while maintaining the mechanical properties of the PP composition.

[0008] Preferably, the laser-sensitive composite comprises ammonium molybdate and antimony tin oxide in a mass ratio of 1:(0.5-4).

[0009] An inappropriate ratio of the two components in the laser-sensitive composite will affect both the marking effect and mechanical properties. Specifically, an excessively high proportion of ammonium molybdate in the laser-sensitive composite results in a greater decrease in contrast after marking the PP composition; similarly, an excessively high proportion of antimony tin oxide leads to a greater decrease in the mechanical properties of the PP composition after marking.

[0010] More preferably, the mass ratio of ammonium molybdate to antimony tin oxide in the laser-sensitive composite is one or any two of the following: 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4.

[0011] More preferably, the laser-sensitive composite comprises ammonium molybdate and antimony tin oxide in a mass ratio of 1:(1-3).

[0012] Preferably, the melt index of the PP resin at 230°C and 2.16 kg is 3-150 g / 10 min.

[0013] Preferably, the melt index of the PP resin at 230°C and 2.16 kg is one or any two of the following values: 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 60 g / 10 min, 70 g / 10 min, 80 g / 10 min, 90 g / 10 min, 100 g / 10 min, 110 g / 10 min, 120 g / 10 min, 130 g / 10 min, 140 g / 10 min, and 150 g / 10 min.

[0014] More preferably, the melt index of the PP resin at 230°C and 2.16 kg is 10-50 g / 10 min.

[0015] Preferably, the melt index of the PS resin at 200°C and 5 kg is 1-20 g / 10 min.

[0016] Preferably, the melt index of the PS resin at 200°C and 5 kg is one or any two of the following: 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 15 g / 10 min, and 20 g / 10 min.

[0017] More preferably, the melt index of the PS resin at 200°C and 5 kg is 6-10 g / 10 min.

[0018] PS and PP resins with suitable melt flow index can be better matched and compatible, which improves the uniformity of PS resin dispersion in PP resin, thereby obtaining better laser marking effect and mechanical properties after marking.

[0019] Preferably, the compatibilizer includes at least one of styrene-ethylene-butene-styrene block copolymer, sulfonated polystyrene, and maleic anhydride graft.

[0020] More preferably, the maleic anhydride graft comprises at least one of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polypropylene.

[0021] Preferably, the whiteness of the white pigment is 94% to 98%.

[0022] Preferably, the white pigment includes at least one selected from titanium dioxide, zinc barium white, and zinc sulfide. More preferably, the titanium dioxide is rutile.

[0023] More preferably, the average particle size of the white pigment is 0.05-1 μm.

[0024] More preferably, the average particle size of the white pigment is a range of one or any two of the following: 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, and 1 μm.

[0025] It should be noted that the difference between the average particle size (processed particle size) of the white pigment described in this invention and its original average particle size (unprocessed average particle size) does not exceed 5%. Therefore, it can be considered that the average particle size of the white pigment remains basically unchanged before and after processing, and the average particle size of the white pigment can be based on its original average diameter.

[0026] Preferably, the PP composition further includes 0.2-1.5 parts of additives, the additives including at least one of antioxidants, lubricants, and coloring agents.

[0027] More preferably, the PP resin has a mass content of ≥85% in the PP composition.

[0028] More preferably, the mass ratio of antioxidant, lubricant and coloring agent in the additive is (0.1-0.5):(0.1-0.5):(1×10⁻⁶).-6 -10×10 -6 ).

[0029] More preferably, the PP composition comprises the following components in parts by weight: PP 90-97 parts, PS 0.4-2 parts, compatibilizer 0.1-1 part, laser-sensitive compound 0.1-1 part, white pigment 2-10 parts, antioxidant 0.1-0.5 parts, lubricant 0.1-0.5 parts, coloring auxiliary agent 1×10 -6 -10×10 -6 share.

[0030] The introduction of trace coloring agents helps to absorb some infrared energy while maintaining the whiteness of the material, thus enhancing the laser marking effect.

[0031] More preferably, the antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010) and tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168).

[0032] More preferably, the antioxidant comprises pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite in a mass ratio of 1:(1-2).

[0033] More preferably, the lubricant includes at least one of zinc stearate and ethylene bis-stearamide (EBS).

[0034] More preferably, the coloring agent comprises carbon black. More preferably, the carbon black comprises pigment carbon black.

[0035] More preferably, the average particle size of the coloring agent is 10-20 nm.

[0036] More preferably, the average particle size of the coloring agent is a range of one or both of 10 nm, 12 nm, 15 nm, 17 nm, and 20 nm.

[0037] It should be noted that the difference between the average particle size (processed particle size) of the coloring auxiliary agent described in this invention and its original average particle size (before processing) does not exceed 5%. Therefore, it can be considered that the average particle size of the coloring auxiliary agent remains basically unchanged before and after processing, and the average particle size of the coloring auxiliary agent can be based on its original average diameter.

[0038] More preferably, the PS resin, compatibilizer, laser-sensitive compound, white pigment, and additives in the PP composition are added in the form of a composite masterbatch.

[0039] This invention also protects a method for preparing the PP composition, comprising the following steps: The components are added to a screw extruder, melted and mixed, and then extruded and granulated to obtain the final product.

[0040] Preferably, the screw extruder is a twin-screw extruder, and the temperature zones of the screw extruder are set as follows: Zone 1 170-190℃, Zone 2 180-200℃, Zone 3 190-210℃, Zone 4 190-210℃, and Zone 5 190-210℃. The screw speed is 200-400 rpm, the length-to-diameter ratio is (40-55):1, and the screw diameter is 30-40 mm.

[0041] The present invention also protects a part obtained by laser marking a part made using the PP composition.

[0042] Compared with the prior art, the present invention has the following beneficial effects: The PP composition provided by this invention, under the combined action of carbon-forming polymer PS and laser-sensitive composite, can improve the laser marking effect on the surface of white PP substrate, greatly improve the contrast and clarity of laser marking, which is beneficial for subsequent identification and further use, and the marked parts can still have excellent mechanical properties. Attached Figure Description

[0043] Figure 1 The diagram shows the marking effect of (A) commercially available PP resin-1 and (B) the marking effect of the PP composition obtained in Example 1 of this invention. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. The raw material information used in each embodiment and comparative example is as follows: PP resin-1: PP M30RH, purchased from Sinopec Zhenhai, melt index is 28.5 g / 10min (230℃, 2.16kg).

[0045] PP resin-2: PP BX3500, purchased from SK Korea, melt index is 10 g / 10min (230℃, 2.16kg).

[0046] PP resin-3: PPH-MN150, purchased from Sinopec Luoyang Petrochemical, with a melt index of 147g / 10min (230℃, 2.16kg).

[0047] PP resin-4: PPH-T03, purchased from Sinopec Yangzi Petrochemical, melt index is 3.5g / 10min (230℃, 2.16kg).

[0048] PS Resin-1: GPPS525, purchased from Shandong Yuhuang, melt index is 7.8g / 10min (200℃, 5kg).

[0049] PS Resin-2: GP125S, purchased from Kumho, South Korea, with a melt index of 7.0 g / 10 min (200℃, 5 kg).

[0050] PS Resin-3: GPPS351, purchased from Shanghai SECCO, melt index is 1.6g / 10min (200℃, 5kg).

[0051] PS Resin-4: PS 145D, purchased from INEOS Styrenex, melt index is 15g / 10min (200℃, 5kg).

[0052] PPE resin: WCP921A, purchased from SABIC, melt index is 12g / 10min (210℃, 5kg).

[0053] Ammonium molybdate: CAS No. 13106-76-8, manufacturer: Merck, Germany.

[0054] Ammonium tungstate: CAS No. 11140-77-5, manufacturer: Merck, Germany.

[0055] Antimony tin oxide: Iriotec 8825, manufactured by Merck, Germany.

[0056] Indium tin oxide: CAS No. 50926-11-9, manufacturer: Zhejiang Yamei Nanotechnology.

[0057] Compatibilizer: Styrene-ethylene-butene-styrene block copolymer, SEBS YH-502T, manufactured by Sinopec Baling Petrochemical.

[0058] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite in a mass ratio of 1:1.5.

[0059] Lubricant: Ethylene bis-stearamide, commercially available.

[0060] Titanium dioxide: average particle size 0.2μm, R104, manufacturer Chemours Chemicals, USA, whiteness 97%.

[0061] Carbon black: average particle size 15 nm. MONARCH 717, manufacturer Cabot.

[0062] Examples 1-9 Examples of the PP composition of the present invention are shown in Table 1.

[0063] The method for preparing the PP composition provided in this embodiment includes the following steps: The components are added to a screw extruder, melted and mixed, and then extruded and granulated to obtain the final product. The screw extruder is a twin-screw extruder with temperature zones set to zones one through five (from the feed port to the die outlet): 180°C, 190°C, 200°C, 200°C, and 220°C. The screw speed is 200-400 rpm, the length-to-diameter ratio is 48:1, and the screw diameter is 35 mm.

[0064] Table 1. Comparative Examples 1-8 The only difference between each comparative example and Example 1 is the type and ratio of components, as shown in Table 2.

[0065] The preparation method of the PP composition provided in this comparative example is consistent with that in Example 1.

[0066] Table 2. Performance testing Sample preparation: The PP compositions obtained in the examples and comparative examples were injection molded into smooth, double-sided color swatches and ISO 179 standard impact test strips, each measuring 83mm*54mm*2mm, using an injection molding machine. The injection molding conditions were 200℃ for 10 seconds. The color swatches / test strips were placed in a constant temperature chamber at 23℃ for 24 hours to cool. The color difference values ​​of the color swatches were measured and recorded using a Datacolor 1050 colorimeter in SCI mode with a D65 light source. The color swatches and standard impact test strips were marked using a Han's Laser EP12 infrared marking machine with a red light wavelength of 1064nm and marking process of 24KHz frequency and 28A current.

[0067] Marking contrast ΔL value test: Use a Datacolor1050 colorimeter in SCI mode with D65 light source to measure the L value of the same area (30mm in diameter) of the color swatch before and after marking. Calculate the difference in L value before and after marking according to the CIE1976 color difference formula, which is the marking contrast ΔL value (ΔL value = L value before marking - L value after marking).

[0068] Impact performance test: The notched impact strength of the marked ISO 179 standard impact specimen was tested using a Zwick / RoellHIT5.5P impact testing machine.

[0069] The results of the above performance tests are shown in Table 3 below. Figure 1 As shown: Table 3. As shown in Table 3 above, the PP composition provided by the present invention has a color difference ΔL≥60.89 after laser marking on the surface of a white PP substrate. The contrast before and after marking is large, which is beneficial for preparing laser-marked PP parts. Moreover, the marked parts still have excellent mechanical properties, with a notched impact strength of up to 8.3 MPa or more.

[0070] As can be seen from Examples 1 and 4-5, when the mass ratio of ammonium molybdate and antimony tin oxide in the laser-sensitive composite is 1:(1-3) as preferred in this invention, the two substances can better synergize their different roles in this invention, thereby obtaining a PP composition with higher contrast before and after marking and better mechanical properties.

[0071] According to Examples 1 and 6-9, the melt index of both PP resin and PS resin affects their composite. When the melt index of PP resin at 230℃ and 2.16kg is the preferred 10-50 g / 10min of this invention, and the melt index of PS resin at 200℃ and 5kg is the preferred 6-10 g / 10min of this invention, the melt indices of PS resin and PP resin can match and be compatible with each other, thereby improving the uniformity of PS resin dispersion in PP resin, and thus obtaining a better laser marking effect and higher mechanical properties after marking.

[0072] According to Comparative Example 1, increasing the amount of laser-sensitive compound added will affect the contrast of the black mark formed after marking and will seriously affect the mechanical properties of the PP composition after marking.

[0073] According to Comparative Examples 2-3, replacing ammonium molybdate with a similar substance, ammonium tungstate, and replacing antimony tin oxide with indium tin oxide, both resulted in the PP composition after marking failing to achieve both high mechanical properties and high contrast. This indicates that only the ammonium molybdate and antimony tin oxide selected in this invention have a better synergistic effect.

[0074] According to Comparative Example 4, with the total amount of resin added remaining constant, excessive PS addition did not affect the contrast before and after marking. It is speculated that this is because excessive PS coated the laser-sensitive composite, thus reducing the response of the laser-sensitive composite to infrared light. At the same time, PS resin carbonized after marking, affecting the mechanical properties of the composition.

[0075] According to Comparative Examples 5 and 7-8, the absence of the laser-sensitive compound, or the addition of only one of the two compounds, ammonium molybdate and antimony tin oxide, will lead to a decrease in marking effect. Furthermore, when the laser-sensitive compound contains only antimony tin oxide, the mechanical properties of the PP composition will be severely reduced.

[0076] According to Comparative Example 6, replacing PS in this application with PPE resin failed to improve the carbonization effect of the PP matrix, resulting in a decrease in marking effect. Furthermore, the compatibility between PPE and PP decreased, leading to a decline in the mechanical properties of the resulting composition.

[0077] 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 modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PP composition, characterized in that, The components include the following parts by weight: 90-97 parts PP resin, 0.4-2 parts PS resin, 0.1-1 parts compatibilizer, 0.1-1 parts laser-sensitive composite, 2-10 parts white pigment; The laser-sensitive composite comprises ammonium molybdate and antimony tin oxide.

2. The PP composition according to claim 1, characterized in that, The laser-sensitive composite comprises ammonium molybdate and antimony tin oxide in a mass ratio of 1:(0.5-4).

3. The PP composition according to claim 1, characterized in that, The melt index of the PP resin at 230℃ and 2.16 kg is 3-150 g / 10min; And / or, the melt index of the PS resin at 200°C and 5 kg is 1-20 g / 10 min.

4. The PP composition according to claim 1, characterized in that, The compatibilizer includes at least one of styrene-ethylene-butene-styrene block copolymer, sulfonated polystyrene, and maleic anhydride graft.

5. The PP composition according to claim 1, characterized in that, The whiteness of the white pigment is 94%~98%; And / or, the white pigment includes at least one of titanium dioxide, zinc barium white, and zinc sulfide; And / or, the average particle size of the white pigment is 0.05-1 μm.

6. The PP composition according to claim 1, characterized in that, The PP composition further includes 0.2-1.5 parts of additives, which include at least one of antioxidants, lubricants, and coloring agents.

7. The PP composition according to claim 6, characterized in that, The mass ratio of antioxidant, lubricant, and coloring agent in the additive is (0.1-0.5):(0.1-0.5):(1×10⁻⁶). -6 -10×10 -6 ).

8. The PP composition according to claim 6, characterized in that, The antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite; And / or, the lubricant includes at least one of zinc stearate and ethylene bis-stearamide; And / or, the coloring aid includes carbon black; And / or, the average particle size of the coloring aid is 10-20 nm.

9. A method for preparing the PP composition according to any one of claims 1-8, characterized in that, Includes the following steps: The components are added to a screw extruder, melted and mixed, and then extruded and granulated to obtain the final product.

10. A component, characterized in that, The part is obtained by laser marking using the PP composition according to any one of claims 1-8.

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