Additives for heat-treated expandable polypropylene

Abstract

A composition is provided that includes a first polypropylene having at least 90 wt. % propylene, based on the weight of the first polypropylene, an alpha anti-nucleating agent, and a beta-nucleating additive. A method for preparing a foamable polypropylene composition is also provided. The method includes: a) blending the first polypropylene, having at least 90 wt. % propylene, based on the weight of the first polypropylene, with the alpha anti-nucleating agent to form a polypropylene blend; b) blending the polypropylene blend with a blowing agent to form a pre-annealed polypropylene composition; and c) annealing the pre-annealed polypropylene composition at an annealing temperature Ta for an annealing time ta to form a foamable polypropylene composition. The foamable polypropylene composition has a first melting peak T1 and a second melting peak T2, as measured by differential scanning calorimetry at a heating rate of 20°C / min.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 964,430, filed October 12, 2022, the disclosure of which is incorporated by reference in its entirety for all purposes.

[0002] The present invention relates to polypropylene compositions useful in foamable applications. [Background technology]

[0003] Expanded polypropylene (EPP) is an engineered plastic foam useful in many applications. Polypropylene offers many attributes that make it desirable for some engineered plastic foam applications. Its high-temperature resistance, high energy absorption, low weight, and high thermal stability compared to other polymers such as polyethylene and polystyrene are some of its attractive properties. These properties may become more important when regulatory restrictions, cost, and / or recycling challenges make certain polymers, such as polystyrene, less attractive. Other desirable attributes of expanded polypropylene are its high weight-to-energy absorption ratio, excellent repeated impact performance, excellent temperature resistance, high durability, and ease of recycling. Additionally, polypropylene can contain recycled materials, has low or no VOC content, is non-toxic, is suitable for food contact, is resistant to oil, chemicals, and weather, is flexible, regains its original shape after static or dynamic loads (i.e., is creep-resistant), its expansion rate is easily adjustable, its water absorption is low, and it is an insulator of both heat and electricity.

[0004] A typical method for producing EPP involves the following. 1) Polypropylene is loaded with a blowing agent to produce small plastic beads loaded with the blowing agent. The blowing agent is typically either carbon dioxide or a low molecular weight alkane such as n-butane or n-pentane. The loading method is carried out by applying heat, pressure, and a gas (e.g., carbon dioxide or an alkane) to the polypropylene pellets in an autoclave to form small gas-infused plastic beads. 2) These gas-injected beads are then placed into a mold and placed in a steam chamber to heat the beads, thereby sintering them and creating foam parts that are molded into complex shapes.

[0005] The key to this process is the first step, the autoclave step, because it changes the crystalline morphology of the polypropylene. Traditional EPP uses a random propylene / ethylene copolymer (RCP) with a single melting point at about 145°C (see Figure 1). By holding the RCP at a constant temperature and pressure and then cooling it, the melting point shifts to two distinct peaks (typically around 140°C and 160°C) (see Figure 2). The lower-melting peak is due to beta crystals, and the higher-melting peak is due to alpha crystals. This "dual crystal structure" or "dual peak" technique is necessary for good sintering in the second step in the steam chamber. The low-melting beta species are necessary for creating good adhesion between the beads, while the high-melting alpha crystals maintain the overall foam structure during the sintering process. Therefore, the steam chamber temperature is set between the minimum (between the two melting peaks).

[0006] However, this EPP production method currently suffers from at least two drawbacks. First, the autoclave step is expensive and slow, making bead production an expensive proposition. If gas could be incorporated more quickly, such as by melt compounding, and the beads could then simply be annealed to achieve double-peak melting behavior without the need for an autoclave, bead production would be more efficient. Second, a wider temperature difference between the two melting peaks would require less thermal control during the second steam chamber step, thus making the production process for EPP foam parts more flexible and robust. Summary of the Invention

[0007] The present inventors have solved these problems by providing a polypropylene composition containing both a beta-nucleating additive and an alpha-antinucleating agent, which provides at least two melting peaks with a wide separation between the peaks. The present inventors also provide a method for producing a polypropylene composition having (at least) a dual-peak melting behavior that does not require the use of an autoclave, but can be produced by other polymer compounding techniques (including more conventional ones) and subsequent annealing.

[0008] A composition is provided that includes a first polypropylene that includes at least 90 wt.% propylene as a polymerized monomer by weight of the first polypropylene, an alpha anti-nucleating agent, and a beta-nucleating additive.

[0009] A method for preparing an expandable polypropylene composition is also provided, the method comprising: a) compounding a first polypropylene comprising at least 90 wt.% propylene as a polymerized monomer by weight of the first polypropylene with an alpha anti-nucleating agent to form a polypropylene blend; b) compounding the polypropylene blend with a blowing agent to form a pre-annealed polypropylene composition; c) annealing the pre-annealed polypropylene composition at an annealing temperature Ta for an annealing time ta to form a foamable polypropylene composition; The expandable polypropylene composition has a first melting peak T1 and a second melting peak T2 as measured by differential scanning calorimetry at a heating rate of 20°C / min. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows the melting behavior of unannealed random copolymer polypropylene (RCP). [Figure 2] The melting behavior of annealed random copolymer polypropylene (RCP) is shown. [Figure 3] 1 shows a second DSC trace of Comparative Example 1 for various annealing temperatures. [Figure 4] 1 shows second melt DSC traces of Example 1 for various annealing temperatures. [Figure 5] FIG. 1 shows Example 1 (enlarged view of the DSC trace of the higher melting point peak between 160° C. and 190° C.). [Figure 6] 1 shows second melt DSC traces of Example 2 for various annealing temperatures. [Figure 7] 1 shows second melt DSC traces of Example 3 at various annealing temperatures. [Figure 8] 1 shows second melt DSC traces of Comparative Example 1 and Examples 1, 2, and 3 at an annealing temperature of 150° C. [Figure 9] Second melt DSC traces are shown for Examples 1, 2, and 3 at an annealing temperature of 160° C., with the end of melt temperature for Comparative Example 1 shown as a reference. [Figure 10] 1 shows the annealed Ziegler-Natta catalyzed random copolymer (propylene / ethylene copolymer) alone of Comparative Example 2. [Figure 11]1 shows a second melting DSC trace for annealed Example 4. [Figure 12] 1 shows the second melt DSC trace for Comparative Example 2 and Example 4 upon annealing at 150° C. [Figure 13] 1 shows a second melt DSC trace for annealed Example 5. [Figure 14] 1 shows the second melt DSC trace for Comparative Example 2 and Example 5 upon annealing at 150° C. [Figure 15] 1 shows a second melting DSC trace for annealed Example 6. [Figure 16] 1 shows the second melt DSC trace for Comparative Example 2 and Example 6 upon annealing at 150° C. [Figure 17] 1 shows the second melt DSC trace for Example 4 and Example 6 upon annealing at 130° C. [Figure 18] 1 shows a second melting DSC trace for annealed Example 7. [Figure 19] 1 shows the second melt DSC trace for annealing at 150° C. for Comparative Example 2 and Example 7. [Figure 20] 1 shows a second melt DSC trace for Comparative Example 2 and Example 7 annealed at 140° C. [Figure 21] 1 shows a second melting DSC trace for annealed Example 8. [Figure 22] Illustrates how the start and end temperatures are determined. DETAILED DESCRIPTION OF THE INVENTION

[0011] composition : A composition for producing expanded polypropylene (EPP) is provided, the composition comprising: a first polypropylene containing at least 90 wt.% propylene as a polymerized monomer, based on the weight of the first polypropylene; an alpha antinucleating agent; a beta-nucleating additive; Includes.

[0012] The first polypropylene is not particularly limited. Non-limiting examples of the first polypropylene include polypropylene homopolymer, isotactic polypropylene, or syndiotactic polypropylene. The first polypropylene may further contain one or more of ethylene, butene, pentene, hexene, or a combination thereof as a polymerized monomer in an amount of up to 6 wt.% based on the weight of the first polypropylene. The first polypropylene may be a random copolymer of propylene and ethylene containing up to 6 wt.% ethylene based on the weight of the first polypropylene.

[0013] The melt flow index of the first polypropylene, as measured in accordance with ISO 1133-1, can be from 0.1 to 500 g / 10 min. For example, the melt flow index of the first polypropylene, as measured in accordance with ISO 1133-1, can be at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, or at least 475 g / 10 min. The melt flow index of the first polypropylene can be at most 500, 490, 480, 470, 460, 450, 440, 430, 420, 410, 400, 300, 390, 380, 370, 360, 350, 340, 330, 320, 310, 300, 290, 280, 270, 260, 250, 240, 230, 220, 210, 200, 175, 150, 125, 100, 75, 50, 25, 20, 15, or at most 10 to 475 g / 10 min, as measured in accordance with ISO-1133-1.

[0014] The first polypropylene may have a molecular weight distribution (also referred to as polydispersity (Mw / Mn)) of 2.0 to 15.0. The molecular weight Mw of the first polypropylene may be from 10,000 g / mol to 1,000,000 g / mol or more, as measured using gel permeation chromatography and polystyrene standards.

[0015] For example, the first polypropylene may have a molecular weight of at least 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, 145,000, 150,000, 155,000, 160,000, 165,000, 170,000, 175,000, 180,000, 185,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, 410,000, , 130,000, 135,000, 140,000, 145,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000 00, 390,000, 400,000, 410,000, 420,000, 430,000, 440,000, 450,000, 455,000, 460,000, 470,000, 480,000, 490,000, 500,000, 510,000, 520,000, 530,000, 540,000, 560,000, 570,000, 580,000, 590,000, 600,000, 610,000, 620,000, 630,000, 640,000, 650,000, 660 ,000, 670,000, 680,000, 690,000, 700,000, 710,000, 720,000, 730,000, 740,000, 750,000, 760,000, 770,000, 780,000, 790,000, 800,000, 810,000, 820,000, 830,000, 840,000, 850,000, 860,000, 870,000, 880,000, 890,000, or at least 900,000 g / mol.For example, the first polypropylene may have a molecular weight of up to 2,000,000, 1,900,000, 1,800,000, 1,700,000, 1,600,000, 1,500,000, 1,400,000, 1,300,000, 1,200,000, 1,100,000, 1,000,000, 95 It may have a weight average molecular weight of 0,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000, or up to 100,000 gm / mol.

[0016] For example, the first polypropylene may have a molecular weight of at least 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, 145,000, 150,000, 155,000, 160,000, 165,000, 170,000, 175,000, 180,000, 185,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, 410,000, , 130,000, 135,000, 140,000, 145,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000 00, 390,000, 400,000, 410,000, 420,000, 430,000, 440,000, 450,000, 455,000, 460,000, 470,000, 480,000, 490,000, 500,000, 510,000, 520,000, 530,000, 540,000, 560,000, 570,000, 580,000, 590,000, 600,000, 610,000, 620,000, 630,000, 640,000, 650,000, 660 ,000, 670,000, 680,000, 690,000, 700,000, 710,000, 720,000, 730,000, 740,000, 750,000, 760,000, 770,000, 780,000, 790,000, 800,000, 810,000, 820,000, 830,000, 840,000, 850,000, 860,000, 870,000, 880,000, 890,000, or at least 900,000 g / mol.For example, the first polypropylene may have a molecular weight of up to 2,000,000, 1,900,000, 1,800,000, 1,700,000, 1,600,000, 1,500,000, 1,400,000, 1,300,000, 1,200,000, 1,100,000, 1,000,000, 900,000, 1000,000, 1100,000, 1200,000, 1300,000, 1400,000, 1500,000, 1600,000, 1700,000, 1800,000, 1900,000, 2000,000, 2100,000, 2200,000, 2300,000, 2400,000, 2500,000, 2600,000, 2700,000, 2800,000, 2900,000, 3000,000, 3100,000, 3200,000, 3300,000, 3400,000, 3500,000, 3600,000, 3700,000, 3800,000, 3900,000, 4100,000, 4200,000, 4300,000, 4400,000, 4500,000, 4600,000, 4700, It may have a number average molecular weight of 50,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000, or up to 100,000 gm / mol.

[0017] The polydispersity of the first polypropylene is at least two of: 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, It can be 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8, 9.0, 9.2, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6, 12.8, 13.0, 13.2, 13.4, 13.6, 13.8, or at least 14.0. The polydispersity of the first polypropylene was up to 15.0, 14.8, 14.6, 14.4, 14.2, 14.0, 13.8, 13.6, 13.4, 13.2, 13.0, 12.8, 12.6, 12.4, 12.2, 12.0, 11.8, 11.6, 11.4, 11.2, 11.0, 10.8, 10.6, 10.4, 10.2, 10.0, It can be 9.8, 9.6, 9.4, 9.2, 9.0, 8.8, 8.6, 8.4, 8.2, 8.0, 7.8, 7.6, 7.4, 7.2, 7.0, 6.8, 6.6, 6.4, 6.2, 6.0, 5.8, 5.6, 5.4, 5.2, 5.0, 4.8, 4.6, 4.4, 4.2, 4.0, 3.8, 3.6, 3.4, 3.2, or up to 3.0.

[0018] The first polypropylene can be produced, for example, using a metallocene catalyst or a Ziegler-Natta catalyst. The first polypropylene can be produced in the gas phase, suspension, solution, or melt. The molecular weight distribution can be reduced by thermal or chemical post-reactor treatment (e.g., decomposition with peroxide ("visbreaking")). The molecular weight can be determined by gel permeation chromatography (GPC), as described in the Examples.

[0019] The first polypropylene used in the present invention can be either a homopolymer of propylene or a random copolymer of propylene and one or more comonomers. The comonomer can be ethylene or a C4-C28 α-olefin, such as butene-1, pentene-1, hexene-1, octene-1, or 4-methyl-pentene-1. According to one embodiment, the random copolymer is a copolymer of propylene and ethylene. The random copolymer of the first polypropylene of the present invention can contain at least 0.1 wt%, or at least 0.2 wt%, or at least 0.5 wt% of the comonomer by weight of the first polypropylene. They can contain up to 6.0 wt%, or up to 5.0 wt%, or up to 4.0 wt% of the comonomer by weight of the first polypropylene.

[0020] Alpha antinucleating agents may include potassium stearate.

[0021] Non-limiting examples of beta-nucleating additives are gamma-crystalline quinacridone dyes; aluminum salts of 6-quinazirin sulfonic acid; disodium salts of o-phthalic acid; isophthalic acid or its derivatives; terephthalic acid or its derivatives; N',N'-dicyclohexyl-2,6-naphthalenedicarboxamide; blends of organic dibasic acids with oxides, hydroxides, or acids of Group II metals; or combinations thereof.

[0022] The composition may further comprise up to 5 wt.% of a second polypropylene, by weight of the composition. The second polypropylene is different from the first polypropylene and comprises at least 99 wt.% of propylene as a polymerized monomer, by weight of the second polypropylene. Importantly, the second polypropylene is a high crystallinity polypropylene, comprising at least 50 wt.% crystallinity, by weight of the second polypropylene. The second polypropylene may comprise at least 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 48, 85, 86, 87, 88, 89, or at least 90 wt.% crystallinity, based on the weight of the second polypropylene. The wt.% crystallinity is measured as described in the Examples section. The second polypropylene is not otherwise particularly limited. Non-limiting examples of the second polypropylene include polypropylene homopolymer, isotactic polypropylene, or syndiotactic polypropylene. The second polypropylene may further include up to 1 wt.% of one or more of ethylene, butene, pentene, hexene, or a combination thereof as polymerized monomers, based on the weight of the second polypropylene. The second polypropylene may be a random copolymer of propylene and ethylene, including up to 1 wt.% of ethylene, based on the weight of the second polypropylene. The melt flow index of the second polypropylene may be 0.1 to 500 g / 10 min, measured according to ISO-1133-1. For example, the melt flow index of the second polypropylene can be at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, or at least 475 g / 10 min, as measured according to ISO-1133-1.The melt flow index of the second polypropylene can be at most 500, 490, 480, 470, 460, 450, 440, 430, 420, 410, 400, 300, 390, 380, 370, 360, 350, 340, 330, 320, 310, 300, 290, 280, 270, 260, 250, 240, 230, 220, 210, 200, 175, 150, 125, 100, 75, 50, 25, 20, 15, or at most 10 g / 10 min, as measured in accordance with ISO-1133-1.

[0023] The second polypropylene may have a molecular weight distribution (Mw / Mn) of 2.0 to 15.0. The molecular weight Mw of the second polypropylene may be from 10,000 g / mol to 1,000,000 g / mol or more, as measured using gel permeation chromatography and polystyrene standards.For example, the second polypropylene may have a molecular weight of at least 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, 145,000, 150,000, 155,000, 160,000, 165,000, 170,000, 175,000, 180,000, 185,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, 410,000, , 130,000, 135,000, 140,000, 145,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000 00, 390,000, 400,000, 410,000, 420,000, 430,000, 440,000, 450,000, 455,000, 460,000, 470,000, 480,000, 490,000, 500,000, 510,000, 520,000, 530,000, 540,000, 560,000, 570,000, 580,000, 590,000, 600,000, 610,000, 620,000, 630,000, 640,000, 650,000, 660 ,000, 670,000, 680,000, 690,000, 700,000, 710,000, 720,000, 730,000, 740,000, 750,000, 760,000, 770,000, 780,000, 790,000, 800,000, 810,000, 820,000, 830,000, 840,000, 850,000, 860,000, 870,000, 880,000, 890,000, or at least 900,000 g / mol.For example, the second polypropylene may have a molecular weight of up to 2,000,000, 1,900,000, 1,800,000, 1,700,000, 1,600,000, 1,500,000, 1,400,000, 1,300,000, 1,200,000, 1,100,000, 1,000,000, 95 It may have a weight average molecular weight of 0,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000, or up to 100,000 gm / mol.

[0024] For example, the second polypropylene may have a molecular weight of at least 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, 145,000, 150,000, 155,000, 160,000, 165,000, 170,000, 175,000, 180,000, 185,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, 410,000, , 130,000, 135,000, 140,000, 145,000, 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000 00, 390,000, 400,000, 410,000, 420,000, 430,000, 440,000, 450,000, 455,000, 460,000, 470,000, 480,000, 490,000, 500,000, 510,000, 520,000, 530,000, 540,000, 560,000, 570,000, 580,000, 590,000, 600,000, 610,000, 620,000, 630,000, 640,000, 650,000, 660 ,000, 670,000, 680,000, 690,000, 700,000, 710,000, 720,000, 730,000, 740,000, 750,000, 760,000, 770,000, 780,000, 790,000, 800,000, 810,000, 820,000, 830,000, 840,000, 850,000, 860,000, 870,000, 880,000, 890,000, or at least 900,000 g / mol.For example, the second polypropylene may have a molecular weight of up to 2,000,000, 1,900,000, 1,800,000, 1,700,000, 1,600,000, 1,500,000, 1,400,000, 1,300,000, 1,200,000, 1,100,000, 1,000,000, 900,000, 1000,000, 1100,000, 1200,000, 1300,000, 1400,000, 1500,000, 1600,000, 1700,000, 1800,000, 1900,000, 2000,000, 2100,000, 2200,000, 2300,000, 2400,000, 2500,000, 2600,000, 2700,000, 2800,000, 2900,000, 3000,000, 3100,000, 3200,000, 3300,000, 3400,000, 3500,000, 3600,000, 3700,000, 3800,000, 3900,000, 4100,000, 4200,000, 4300,000, 4400,000, 4500,000, 4600,000, 4700, It may have a number average molecular weight of 50,000, 900,000, 850,000, 800,000, 750,000, 700,000, 650,000, 600,000, 550,000, 500,000, 450,000, 400,000, 350,000, 300,000, 250,000, 200,000, 150,000, or up to 100,000 gm / mol.

[0025] The polydispersity of the second polypropylene is at least 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8, 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 0.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8, 9.0, 9.2, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6, 12.8, 13.0, 13.2, 13.4, 13.6, 13.8, or at least 14.0. The polydispersity of the second polypropylene was up to 15.0, 14.8, 14.6, 14.4, 14.2, 14.0, 13.8, 13.6, 13.4, 13.2, 13.0, 12.8, 12.6, 12.4, 12.2, 12.0, 11.8, 11.6, 11.4, 11.2, 11.0, 10.8, 10.6, 10.4, 10.2, 10.0, It can be 9.8, 9.6, 9.4, 9.2, 9.0, 8.8, 8.6, 8.4, 8.2, 8.0, 7.8, 7.6, 7.4, 7.2, 7.0, 6.8, 6.6, 6.4, 6.2, 6.0, 5.8, 5.6, 5.4, 5.2, 5.0, 4.8, 4.6, 4.4, 4.2, 4.0, 3.8, 3.6, 3.4, 3.2, or up to 3.0.

[0026] The second polypropylene can be produced, for example, using a metallocene catalyst or a Ziegler-Natta catalyst. The second polypropylene can be produced in the gas phase, suspension, solution, or melt. The molecular weight distribution of the second polypropylene can be reduced by thermal or chemical post-reactor treatment (e.g., peroxide decomposition ("visbreaking")). The molecular weight can be determined by gel permeation chromatography (GPC), as described in the Examples.

[0027] The second polypropylene used in the present invention can be either a homopolymer of propylene or a random copolymer of propylene and one or more comonomers. The comonomer can be ethylene or a C4-C28 α-olefin, such as butene-1, pentene-1, hexene-1, octene-1, or 4-methyl-pentene-1. According to one embodiment, the random copolymer is a copolymer of propylene and ethylene. The random copolymer of the second polypropylene of the present invention can contain at least 0.1 wt%, or at least 0.2 wt%, or at least 0.5 wt% of the comonomer by weight of the second polypropylene. They can contain up to 1.0 wt%, or up to 0.3 wt%, or up to 0.5 wt% of the comonomer by weight of the second polypropylene.

[0028] After annealing at an annealing temperature Ta for an annealing time ta, the composition has a first melting peak T1 and a second melting peak T2 as measured by differential scanning calorimetry at a heating rate of 20°C / min. According to certain embodiments, the annealing temperature Ta can be between 90°C and 200°C. According to certain embodiments, the annealing temperature can be between 100°C and 180°C or between 120°C and 160°C. According to some embodiments, the annealing temperature Ta can be at least 90°C, at least 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, or at least 175°C. According to certain embodiments, the annealing temperature may be up to 200°C, or up to 195, 190, 185, 180, 175, 170, 165, 160, 155, 150, 145, 140, 135, 130, or up to 125°C. According to certain embodiments, the first melting peak T1 may be between 110°C and 165°C. According to certain embodiments, the first melting peak T1 may be between 135°C and 165°C or between 140°C and 155°C. According to certain embodiments, the second melting peak T2 is between 150°C and 180°C. According to some embodiments, the second melting peak is between 155°C and 175°C or between 160°C and 170°C. According to one embodiment, the composition may have a third melting peak T3. The third melting peak T3 can be between 160° C. and 180° C. or between 165° C. and 175° C. The melting peak is measured as described in the Examples.

[0029] The composition as a whole may have a crystallinity of at least 25 wt. % based on the total weight of the first polypropylene, as measured as described in the Examples.

[0030] The composition may further comprise a blowing agent. Non-limiting examples of suitable blowing agents are gases (such as CO, nitrogen, etc.), small alkanes (such as n-butane or n-pentane), and combinations thereof.

[0031] The composition may be in the form of a masterbatch. A masterbatch is a concentrated composition used to precisely dispense additives into a polypropylene composition. The carrier for the masterbatch may be a first polypropylene or a second polypropylene or another polymer or polypropylene. In the masterbatch, the alpha anti-nucleating agent and the beta nucleating additive together comprise 0.1 to 80 wt. %, based on the total weight of the masterbatch composition.

[0032] method : A method for preparing an expandable polypropylene composition is provided, the method comprising: a) compounding a first polypropylene comprising at least 90 wt.% propylene as a polymerized monomer by weight of the first polypropylene with an alpha anti-nucleating agent to form a polypropylene blend; b) compounding the polypropylene blend with a blowing agent to form a pre-annealed polypropylene composition; c) annealing the pre-annealed polypropylene composition at an annealing temperature Ta for an annealing time ta to form a foamable polypropylene composition; wherein the expandable polypropylene composition has a first melting peak T1 and a second melting peak T2 as measured by differential scanning calorimetry at a heating rate of 20°C / min.

[0033] According to one embodiment, the pre-annealed polypropylene may have a third melting peak T3.

[0034] According to another embodiment, step a) of the method may further comprise compounding a beta-nucleating additive with the first polypropylene and the alpha anti-nucleating agent to form a polypropylene blend. According to one embodiment, at least one of the beta-nucleating additive and the alpha anti-nucleating agent may be in the form of a masterbatch. According to one embodiment, steps a) and b) may be performed in a single compounding operation.

[0035] According to another embodiment, step b) may further comprise pelletizing the pre-annealed polypropylene composition.

[0036] A method for preparing an expanded polypropylene composition is provided. The method includes heating an expandable polypropylene composition to an expansion temperature greater than T1 and less than T2. ​​The heating step can be performed at a pressure less than 1 atm. For example, the pressure can be 0.95 atm, or 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, or 0.50 atm, or less. [Example]

[0037] method : Differential scanning calorimetry (DSC) : DSC experiments were performed on a Discovery 250 instrument manufactured by TA Instruments on 5-7 milligram samples. Samples were run under nitrogen and the instrument was calibrated using an indium standard as described in the Examples.

[0038] Non-isothermal testing was performed according to ASTM 3418-21. Specifically, the sample was equilibrated at 50°C for 1 minute, ramped to 210°C at 10°C / min, held at 210°C for 5 minutes, cooled to 50°C at -10°C / min, held at 50°C for 1 minute, reheated to 190°C at 10°C / min, and then cooled to 50°C to terminate the test. This method provides crystallization data, such as crystallization temperature and enthalpy, during the cooling trace. The second heating trace provides melting temperature and enthalpy data.

[0039] For DSC testing of annealing at different temperatures, an internal procedure was used and is detailed below.

[0040] Kneading : In preparation for compounding, the reactor polypropylene powder was blended with the additives prior to introduction into the extruder. Blending was carried out for 1 minute in a high-intensity mixer. The high-intensity mixer was a Prodex Corporation Model 18JSS.

[0041] The powders were blended and then fed into a 1 1 / 4" single screw extruder. The extruder was an American Kuhne, Model AK 125 24 AC 5HP ULT. The extruder temperature settings were 410°F / 420°F / 420°F / 430°F / 430°F / 430°F for Zone 1 (feed) / Zone 2 / Zone 3 / Clamp / Die 1 / Die 2. The extruder was equipped with a 100 mesh screen pack. After passing through the die, the strands were passed through a water bath held at room temperature and pelletized.

[0042] Melt Flow Index (MFI) : MFI measurements were performed in accordance with ASTM-D1238-20. The test equipment was a Tinius Olsen Plastometer (either model MP600 or MP1200). Each test consumes approximately 7 grams of pellets. All MFI tests were performed at 230°C per ASTM standards using an orifice with a diameter of 2.095 mm and a length of 8.00 mm. The melt temperature was 230°C.

[0043] Mw, Mn : The weight-average and number-average molecular weights (Mw, Mn) were determined by gel permeation. A Polymer Char GPC-IR with three columns was used as the GPC instrument. The first two columns were Shodex AT-80 M / S (part number 34200) linear columns. The third column was a Waters Ultrastyragel high-temperature linear (part number 35554) column. A 16 mg sample was placed in a 10 ml vial, to which 8 ml of trichlorobenzene (TCB) solvent was automatically added using the GPC-IR autosampler. The samples were run at 135-145 °C. Analysis of the eluate was performed via an infrared detector. Polystyrene samples were used.

[0044] Crystallinity : Crystallinity was determined by measuring the heat of fusion of each sample and then dividing the result by the heat of fusion of a 100% crystalline sample of polypropylene. The value for 100% crystalline polypropylene used herein is 207 J / g. The heat of fusion of each sample is determined after annealing using a non-isothermal test under ASTM 3418-21 or under a heating ramp.

[0045] End point and start point of melting : The melting onset and end points were determined in a non-isothermal heating gradient. They were determined by extending tangent lines from the baseline and melting curve, and the temperatures were defined by where the two lines intersected. Figure 9 illustrates an example of the end temperature. Figure 22 also provides an illustration of the determination of the melting onset and end points.

[0046] All percentages are by weight unless otherwise stated.

[0047] All parts (eg, parts per million (ppm)) are by weight unless otherwise specified.

[0048] Examples 1-3, Comparative Example 1: Effect of Beta-Nucleating Additives and Alpha-Anti-Nucleating Agents on the Melting Behavior of High Crystallinity Polypropylene The following four compositions shown in Table 1 below were prepared using a polypropylene homopolymer (Total Energies 3270) having a melt flow index MFI of 2 gm / 10 min as measured by ASTM D1238-20 as the base polymer: [Table 1]

[0049] Irganox® 1010 (BASF) is a trademark of pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate. Its Chemical Abstracts Service number (CAS number) is 6683-19-8. Irgafos® 168 (BASF) is a trademark of tris(2,4-ditert-butylphenyl)phosphite. Its CAS number is 31570-04-4. The CAS number for calcium stearate is 1592-23-0. The CAS number for potassium stearate is 593-29-3. NJ Star NU-100 (New Japan Chemical Co.) is N,N-dicyclohexyl-2,6-naphthalenedicarboxamide. Its CAS number is 153250-52-3.

[0050] DSC tests were carried out as described below to determine the effect of beta-nucleating additives and alpha-antinucleating agents, both alone and in combination, on the melting behavior of polypropylene. 1. Ramp 20°C / min to 210°C. Hold for 5 minutes. 2. Ramp to 50°C at -20°C / min. Hold for 1 minute. 3. Ramp to 120°C at 20°C / min. Hold for 15 minutes. This is the 120°C annealing treatment. 4. Ramp to 23°C at -20°C / min. Hold for 1 minute. 5. Ramp to 190°C at 20°C / min. Hold for 1 minute. 6. Ramp to 23°C at -20°C / min. Hold for 1 minute. 7. Ramp to 130°C at 20°C / min. Hold for 15 minutes. This is the 130°C annealing treatment. 8. Ramp to 23°C at -20°C / min. Hold for 1 minute. 9. Ramp to 190°C at 20°C / min. Hold for 1 minute. 10. Ramp to 23°C at -20°C / min. Hold for 1 minute. 11. Ramp to 140°C at 20°C / min. Hold for 15 minutes. This is the 140°C annealing treatment. 12. Ramp to 23°C at -20°C / min. Hold for 1 minute. 13. Ramp to 190°C at 20°C / min. Hold for 1 minute. 14. Ramp to 23°C at -20°C / min. Hold for 1 minute. 15. Ramp to 150°C at 20°C / min. Hold for 15 minutes. This is the 150°C annealing step. 16. Ramp to 23°C at -20°C / min. Hold for 1 minute. 17. Ramp at 20°C / min to 190°C. Hold for 1 minute. 18. Ramp to 23°C at -20°C / min. Hold for 1 minute. 19. Ramp to 160°C at 20°C / min. Hold for 15 minutes. This is the 160°C annealing step. 20. Ramp to 23°C at -20°C / min. Hold for 1 minute. 21. Ramp at 20°C / min to 190°C. Hold for 1 minute. 22. Cool to room temperature and end the test.

[0051] The DSC results for Comparative Example 1, shown in Figure 3, show how the baseline polymer, a high-crystallinity polypropylene resin, responded to the annealing step at each hold temperature. None of the annealing temperatures produced the desired double-peak behavior useful for producing polypropylene foam. Instead, the result was a shift of the lower-melting endotherm to hotter temperatures. This resulted in the formation of a more pronounced shoulder on the left side of the DSC trace, which gradually pushed into the main body of the peak. This behavior changed with annealing at 160°C, where the peak melting temperature shifted and increased while maintaining a unimodal shape. This indicates that annealing of high-crystallinity polypropylene does not produce the double-peak behavior typical of random copolymer polypropylenes used in foamed polypropylene grades. At all annealing temperatures, negligible unmelted species appeared to be present at 190°C. The emergence of the higher-melting peak can be quantified in terms of the increasing number of higher-melting species with successively higher temperatures. Quantification can be achieved by the "end of melting temperature (Tes)," which is defined similarly to the melting onset temperature. The end of melting temperature is determined by taking the intersecting temperature between the drop line from the melting curve and the baseline. The shift in peak melting temperature is shown in Table 2. As shown in Table 2, annealing temperatures between 120°C and 150°C resulted in a total peak shift of only about 1°C. On the other hand, an annealing temperature of 160°C resulted in a melting temperature increase of nearly 4°C. [Table 2]

[0052] Table 1 also shows that a similar change in melting end temperature was observed. Annealing temperatures between 120°C and 150°C resulted in a shift in the end temperature (Tes) of slightly more than 1°C. This shift was closer to 6°C when the annealing temperature was increased from 150°C to 160°C.

[0053] The introduction of 2000 ppm of the beta-nucleating additive in Example 1 resulted in a bimodal melting endotherm when the sample was annealed at temperatures between 120°C and 150°C, as shown in Figure 4. Furthermore, these data show that the size and shape of the two melting peaks, as well as their shape, changed depending on the annealing temperature. With increasing annealing temperature, the second, higher-melting peak also increased in height. Furthermore, with increasing annealing temperature, the area under the second melting peak also increased, revealing an increased number of high-melting crystals. The second, higher-melting peak itself also shifted to a higher melting point. Clearly, all of these effects are due to the presence of the beta-nucleating additive. Figure 5 shows the same DSC data as Figure 4, but plotted over a smaller temperature range to more clearly demonstrate the effect of the beta-nucleating additive on the second melting peak at various annealing temperatures. These higher-melting species are important in EPP (expanded polypropylene) processing. Without wishing to be bound by any particular theory, it is believed that these high melting point crystallites may create physical crosslinks, thereby providing a framework for maintaining the foam structure even at higher temperatures.

[0054] The attributes of the melting peak for the polymer containing the beta-nucleating additive (Example 1) are shown in Table 2. The two peaks (lower and higher melting) had a difference of around 12° C. to 13° C. This spread, while narrower than the 20° C. typical for random copolymers of propylene and ethylene, is still substantial and, importantly, is completely absent from the same polymer annealed in the same manner without the beta-nucleating additive, as shown above in Comparative Example 1. [Table 3]

[0055] The melting end temperatures of Comparative Example 1 and Example 1 were also determined to evaluate the effect of adding a beta-nucleating additive. Surprisingly, it was found that the addition of the beta-nucleating additive not only promotes the formation of higher melting species, but also supports the production of lower melting species within the typical range of beta crystals. This effect is important for many applications requiring high temperature resistance, including the steam chest portion of the EPP process. Table 3 provides data supporting this. As can be seen in Table 3, the beta-nucleating additive is more effective in producing higher melting species at the hotter annealing temperatures of 150°C and 160°C. [Table 4]

[0056] Next, in Example 2, the effect of adding an alpha anti-nucleating agent on the response to various annealing temperatures was determined. The DSC curves of Example 2 compared to Comparative Example 1 are shown in Figure 5. As can be seen in Figure 5, annealing at 120°C produced a unimodal profile. Surprisingly, annealing at temperatures of 130°C, 140°C, and 150°C produced a bimodal melting endotherm. As the annealing temperature gradually increased, the second melting peak shifted in temperature to a higher peak. Finally, as seen in Example 1, which contained the beta nucleating additive, at an annealing temperature of 160°C, the peak became unimodal. However, it exhibited a very strong lower-temperature shoulder.

[0057] Similar to the addition of the beta-nucleating additive in Example 1, the addition of the alpha anti-nucleating agent in Example 2 produced higher melting point species compared to Comparative Example 1 at an annealing temperature of 160°C.

[0058] The attributes of these melting peaks shown in Figure 5 are given in Table 4. These two peaks differ by just over 13°C. This spread is narrower than the 20°C typical for random copolymer polypropylene, but is still substantial and, importantly, is not seen in the comparative examples that do not contain an alpha antinucleating agent. [Table 5]

[0059] As can be seen from the DSC trace in Figure 5 and Table 4, alpha nucleation Inhibitor When added, moreover High melting point seeds formed This result was unexpected because alpha crystals have a higher melting point than beta crystals, and is important for many applications requiring high temperature resistance, including the steam chest portion of the EPP process.

[0060] Table 6 presents data illustrating this effect. Table 6 shows that at the hotter annealing temperatures of 150°C and 160°C, the effect of higher melting temperatures in the presence of the alpha anti-nucleating agent side is greater. [Table 6]

[0061] Example 3 contains both a beta-nucleating additive and an alpha anti-nucleating agent. The effect on melting behavior of combining an alpha anti-nucleating agent with a beta-nucleating additive is shown in Figure 7. As shown, using these two additives together can produce the desired bimodal melting endotherm. The attributes of these melting peaks are shown in Table 7. The two peaks have a difference of just over 11.5°C to 12.5°C. While this spread is narrower than the 20°C typical for random copolymer polypropylene, it is still significant and is not seen in high crystallinity polypropylene homopolymers. [Table 7]

[0062] The effect of using a beta-nucleating additive together with an alpha-anti-nucleating agent on the finish temperature at these various annealing temperatures is discussed below.

[0063] Surprisingly, the addition of an alpha anti-nucleating agent together with a beta-nucleating additive promotes the formation of higher melting species. urged This result was unexpected since the alpha morphology crystallites melt at a higher temperature than the beta crystallites. This significance is important for many applications requiring high temperature resistance, including the steam chest portion of the EPP process. Table 8 provides supporting data. As can be seen in Table 8, the alpha anti-nucleating agent profile is favored and grown at the hotter annealing temperatures of 150°C and 160°C. [Table 8]

[0064] Visual evaluation of the annealing at 150°C of Comparative Example 1 and Examples 1-3 is shown in Figure 8. Interestingly, the peak intensities of Example 3 had peak heights for the first and second peaks between those of Example 1, which has only a beta-nucleating additive, and Example 2, which has only an alpha anti-nucleating agent. Therefore, the combination of a beta-nucleating additive and an alpha anti-nucleating agent surprisingly works together to provide the desired double melting peak behavior. By using a combination of a beta-nucleating additive and an alpha anti-nucleating agent, it is possible to tailor the crystallization behavior to an industrially optimal level.

[0065] The second finding is that the alpha anti-nucleating agent at the 150°C annealing temperature provided a more balanced peak size between the first and second melting peaks. This strength of response compared to the beta nucleating additive clearly demonstrates that the crystallization kinetics can differ between these two additives, giving practitioners two separate tools to modify and optimize performance for a given annealing process. For example, what is optimal for annealing slit film yarns may be completely different from what is optimal for processes like expanded polypropylene (EPP).

[0066] The effect of alpha anti-nucleating agents, beta-nucleating additives, and the combination of the two on the formation of higher melting crystallites is illustrated in Figure 9. The melting end temperature for Comparative Example 1 (no beta-nucleating additive and no alpha anti-nucleating agent) baseline TotalEnergies 3270 is 179.96°C, while the higher melting endothermic peaks for Examples 1-3 are between 179.08°C and 179.45°C. Clearly, these additives together provided a significant number of crystal species that melted above 180°C and crystal species that melted above 185°C.

[0067] It is known in the art that crystallites can act as physical crosslinks. Therefore, as temperatures increase, these formulations of Examples 1-3 are better able to resist deformation, leading to higher Vicat softening points and higher heat deflection temperatures. Because the remaining crystallites significantly increase the melt's resistance to flow, these formulations also become more viscous than the baseline Comparative Example 1 formulation. This attribute is desirable for foaming processes such as EPP, as high-melting species are necessary to help maintain structural integrity in the steam-chamber molding process. High-melting crystallites are also expected to be useful in other processes where polymers are softened for further shaping, such as thermoforming of preforms and injection stretch-blow molding.

[0068] Comparative Example 2 and Examples 4-8. Effect of Adding High Crystallinity PP with a Beta-Nucleating Additive and an Alpha-Anti-Nucleating Agent on the Melting Behavior of a Ziegler-Natta Catalyzed Random Copolymer (Propylene / Ethylene Copolymer) Test materials and conditions TotalEnergies 6575 was used as the base polymer powder in the preparation of the six compounds shown in Table 9 below. This polymer is an 8 MFR Ziegler-Natta polypropylene. Its melting temperature is approximately 145°C. This MFR and melting temperature are typical of RCPs used in EPP applications. All six compounds contained 1000 ppm Irganox® 1010 and 1000 ppm Irgafos® 168 as antioxidants. Compound numbers and descriptions are shown in Table 9 below. [Table 9-1] [Table 9-2]

[0069] DSC testing of the compositions shown in Table 9 was carried out as follows. 1. Ramp 20°C / min to 210°C. Hold for 5 minutes. 2. Ramp to 50°C at -20°C / min. Hold for 1 minute. 3. Ramp to 120°C at 10°C / min. Hold for 15 minutes. This is the 120°C annealing treatment. 4. Ramp to 23°C at -10°C / min. Hold for 1 minute. 5. Ramp to 210°C at 20°C / min. Hold for 1 minute. 6. Ramp to 23°C at -20°C / min. Hold for 1 minute. 7. Ramp to 130°C at 10°C / min. Hold for 15 minutes. This is the 130°C annealing treatment. 8. Ramp to 23°C at -10°C / min. Hold for 1 minute. 9. Ramp at 20°C / min to 210°C. Hold for 1 minute. 10. Ramp to 23°C at -20°C / min. Hold for 1 minute. 11. Ramp to 140°C at 10°C / min. Hold for 15 minutes. This is the 140°C annealing step. 12. Ramp to 23°C at -10°C / min. Hold for 1 minute. 13. Ramp to 210°C at 20°C / min. Hold for 1 minute. 14. Ramp to 23°C at -20°C / min. Hold for 1 minute. 15. Ramp to 150°C at 10°C / min. Hold for 15 minutes. This is the 150°C annealing step. 16. Ramp to 23°C at -10°C / min. Hold for 1 minute. 17. Ramp at 20°C / min to 210°C. Hold for 1 minute. 18. Ramp to 50°C at -20°C / min. Hold for 1 minute. 19. Cool to room temperature and end the test.

[0070] result We begin by analyzing how the baseline Comparative Example 2 (TotalEnergies 6575) responded to the annealing step at each annealing temperature. As can be seen in Figure 10, the melting endotherm changed over the annealing temperature range of 120°C to 150°C. Annealing at 120°C created a broad, lower melting shoulder from about 125°C to about 135°C, which then rose to a peak at 145°C. Annealing at 130°C and 140°C reduced the prominence of the lower melting shoulder. Annealing at 140°C, in particular, also increased the peak height and pushed out the end peak temperature. Annealing at 150°C was variable. A small peak above 160°C formed, which qualitatively matched what was desired in the double peak technique. The lower melting peak was bimodal and very broad.

[0071] These results show that while some aspects of the melting behavior of Comparative Example 2 (TotalEnergies 6575) are similar to that of Comparative Example 1 (TotalEnergies 3270) seen in Figure 3, the random copolymer polypropylene of Comparative Example 2 also possesses some distinctive features. Specifically, no trimodal melting endotherm was observed in the tested Comparative Example 1 (TotalEnergies 3270), even up to an annealing temperature of 160°C. Because the results for Comparative Example 2 demonstrated that trimodal melting peaks are possible, the term "multimodal" is used to apply to such behavior. As used herein, "multimodal" means that the melting endotherm exhibits two or more melting temperatures.

[0072] The complexity of the melting endotherm for Comparative Example 2 is shown in Table 10. The melting onset temperature increases with increasing annealing temperature toward the 150°C annealing temperature, then drops to just above 111°C. Over the same 120°C to 140°C range, the melting end temperature increases, but not as rapidly. As a result, the melting temperature range (i.e., the difference between the end Tm and the onset Tm) narrows. At the 150°C annealing temperature, the behavior changes. The melting temperature range increases to over 55°C, with an end Tm near 167°C, and a distinct melting peak above 160°C appears. This melting point above 160°C is important in EPP processing because, as seen in the double-peak melting behavior of polypropylene, crystalline seed melting around 160°C is important in maintaining the overall foam structure. [Table 10]

[0073] Introducing a beta-nucleating additive to TotalEnergies 6575 in Example 4 created an additional melting endotherm, indicating the presence of a strong interaction (FIG. 11). Qualitative findings in Example 4 compared to the Comparative Example 2 baseline include the following: Example 4 increases the prominence of the low melting peak / shoulder. Example 4 shows an increased width of the melting endotherm range at 130°C and 140°C, which suggests a more robust processing window for EPP. Annealing at 150°C resulted in a more pronounced high-melting peak above 160°C (Figure 12).

[0074] Taken together, these features would be attractive in processes that use annealing, such as EPP, since the inclusion of a beta-nucleating additive altered the melting behavior. Furthermore, increasing the annealing temperature to form higher melting point species would ensure that crystalline seeds are present to help maintain the foam structure in EPP.

[0075] The complexity of the melting endotherm for Example 4 is shown in Table 11. Unlike Comparative Example 2, multimodal melting endotherms occurred at three of the four annealing temperatures. The peak melting temperatures tended to be lower for Example 4 than for Comparative Example 2. Furthermore, the melting end temperatures for Example 4 tended to be higher. As a result, the desirable melting temperature range for Example 4 increased over the range of annealing temperatures tested. [Table 11]

[0076] Example 5 showed that the introduction of an alpha anti-nucleating agent into TotalEnergies 6575 produced a smaller effect than the beta-nucleating additive effect (Figure 13). The qualitative findings for Example 5 compared to the Comparative Example 2 baseline appear nearly identical, with one exception. Annealing Example 5 at 150°C resulted in a more pronounced high melting point peak above 160°C (Figure 14). This could be attractive for some EPP processes. This suggests that RCPs containing alpha anti-nucleating agents may be processed very similarly to standard RCP grades, but that more high melting species may be required to maintain the EPP foam structure.

[0077] The melting endotherm data for Example 5 is shown in Table 12. The data is nearly identical to Comparative Example 2. The results are encouraging because they demonstrate excellent reproducibility of the DSC testing procedure. The results also provide strong confidence that the larger melting peak (above 160°C) shown in Figure 14 is genuine and not a testing artifact. [Table 12]

[0078] Example 6, which combined alpha anti-nucleating and beta nucleating additives in TotalEnergies 6575, provided a synergistic effect on melting behavior (Figure 12). Qualitative findings for Example 6 compared to Comparative Example 2 include the following: All DSC traces showed multimodal melting exotherms. Increased prominence of the low melting peak / shoulder was observed. An expansion of the melting endotherm range was observed at 130°C and 140°C, which provides a desirable wider processing window for EPP. Similar to the compositions of Examples 4 and 5, the composition of Example 6 exhibited a more pronounced high melting point peak above 160°C when annealed at 150°C (Figure 13).

[0079] The overall trend of Example 6 is similar to, but not a direct replica of, Example 4. The combination of an alpha anti-nucleating agent with a beta-nucleating additive resulted in a different melting behavior than either additive alone.

[0080] The melting endotherm data for Example 6, shown in Table 13, is similar to the behavior of Example 4. The melting temperature range is very similar at each annealing temperature, and this is also true for most of the peak melting temperatures. The melting behavior is different from that of the undoped Comparative Example 2. [Table 13]

[0081] Figure 14 shows the second melt DSC traces of Examples 4 and 6 after annealing at 130°C. Figure 14 shows how the beta-nucleating additive and alpha anti-nucleating agent work together in TotalEnergies 6575 compared to the beta-nucleating additive alone. Example 6 has a lower melting first peak and produces a distinct second peak, as shown in Figure 15. This result is unusual. Since the alpha crystals are the higher melting species in polypropylene, the alpha nucleating agent is the higher melting species. Inhibitor The addition of be prompted A person skilled in the art would never have predicted that this would happen.

[0082] In contrast, Example 4 only has a pronounced shoulder rather than a distinct second peak (i.e., the tangent line after the first peak never equals zero as a local minimum would provide a mathematically defined boundary between the first and second peaks).

[0083] In a further experiment, TotalEnergies 3270, a high crystallinity polypropylene, was compounded as a resin modifier into TotalEnergies 6575 at 5% to produce Example 7.

[0084] When TotalEnergies 3270 is incorporated into TotalEnergies 6575 at 5%, its effect on the melting behavior after annealing at 150°C can be seen (Figures 18 and 19). A high melting peak above 160°C dominates the shape of the DSC trace. Therefore, the addition of a small amount of high crystallinity PP such as TotalEnergies 3270 enhanced the size of this high melting peak.

[0085] Another effect of adding high crystallinity polypropylene is as follows: After annealing at 140°C, the addition of high crystallinity polypropylene created a shift to higher melting species (Figure 20). This shift to higher temperatures was replicated at lower annealing temperatures. Such behavior may prove useful for applications other than EPP, such as medical applications that require autoclaving articles at high temperatures without part distortion.

[0086] The addition of 5% TotalEnergies 3270 is shown in Table 14. Most significant was the shift in the melting finish temperature to higher temperatures. This feature is useful in itself because it allows for higher annealing temperatures without eliminating high-melting crystallites. Such a feature may provide a more robust annealing temperature range in the EPP process. This shift also increases the melting temperature range, as the onset temperature tends to remain similar to that of the base TotalEnergies 6575 resin. [Table 14]

[0087] Example 8 was then compounded with 5% TotalEnergies 3270 and 2000 ppm alpha anti-nucleating agent. Absent complementary behavior, Example 8 should mirror the performance of Example 7. Any deviation from Example 7 would support a synergistic effect, especially if it were qualitatively similar to the trends obtained from the other Example 4-6 compounded mixtures.

[0088] Initial DSC results for Example 8 followed the general pattern seen with Example 7N21053-5 (Figure 18). When annealed at 150°C, Example 8 gave a very strong melting peak above 160°C (Figure 21). At lower annealing temperatures, the peak melting temperature shifted to lower temperatures, and a lower melting shoulder developed.

[0089] As can be seen in Example 8 and Figure 21, there was a slight but consistent effect of blending TotalEnergies 6575 with TotalEnergies 3270 and a beta-nucleating agent. The end of melting temperature was consistently higher than the Example 7 (TotalEnergies 6575 / TotalEnergies 3270-95 / 5%) composition. The onset of melting temperature remained the same for Examples 7 and 8, but the Example 8 blend also experienced an increased melting temperature spread. [Table 15] [Table 16-1] [Table 16-2]

[0090] This disclosure relates to modifying the melting behavior of random copolymer polypropylene (RCP) by annealing at various temperatures in conjunction with the addition of small amounts of beta-nucleating additives, alpha-nucleating inhibitors, and high crystallinity polypropylene. Beneficial characteristics were achieved through the use of this additive / modifier. After annealing, there was an increase in melting species with higher melting points (≥160°C), as visually indicated by the size of the melting endotherm peak compared to the unadded RCP baseline. The melting end temperature generally shifted to higher temperatures. A multimodal melting endotherm occurred compared to the unadded RCP baseline. The melting temperature range, defined as the melting end temperature minus the melting onset temperature, increased.

[0091] Taken together, these results demonstrate that RCP thermal performance has been improved to better suit end-use applications that have a high-temperature conditioning / annealing step. The production of expanded polypropylene (EPP) is one commercial example where this is done. Other applications are in articles that are subjected to high-temperature sterilization (such as autoclave and steam sterilization) and in other polypropylene processing techniques where the article is reheated for further forming (such as thermoforming of sheet or injection stretch blow molding of preforms).

[0092] In some embodiments, the invention herein can be construed to exclude any element or process that does not materially affect the basic and novel characteristics of the composition or process. Further, in some embodiments, the invention can be construed to exclude any element or process not specified herein.

[0093] Although the invention is illustrated and described herein with reference to specific embodiments, it is not intended to limit the invention to the details shown. Rather, various modifications of the details may be made within the scope and range of equivalents of the claims without departing from the invention.

Claims

1. a first polypropylene comprising, as a polymerized monomer, at least 90 wt. % propylene by weight of the first polypropylene; an alpha antinucleating agent; a beta-nucleating additive; A composition comprising:

2. 2. The composition of claim 1, wherein after annealing at an annealing temperature Ta for an annealing time ta, the composition has a first melting peak T1 and a second melting peak T2 as measured by differential scanning calorimetry at a heating rate of 20°C / min.

3. 3. The composition of claim 2, wherein the composition has a third melting peak T3 as measured by differential scanning calorimetry at a heating rate of 20°C / min.

4. The composition of claim 1 , wherein the alpha antinucleating agent comprises potassium stearate.

5. 10. The composition of claim 1, wherein the beta-nucleating additive comprises at least one of a gamma-crystalline form of a quinacridone dye; an aluminum salt of 6-quinazirin sulfonic acid; a disodium salt of o-phthalic acid; isophthalic acid or a derivative thereof; terephthalic acid or a derivative thereof; N',N'-dicyclohexyl-2,6-naphthalenedicarboxamide; a blend of an organic diacid with a Group II metal oxide, hydroxide, or acid; or a combination thereof.

6. 10. The composition of claim 1, wherein the composition further comprises up to 5 wt. % of a second polypropylene by weight of the composition, the polypropylene polymer being different from the first polypropylene and comprising at least 99 wt. % of propylene as a polymerized monomer by weight of the second polypropylene and at least 50 wt. % of crystallinity by weight of the second polypropylene.

7. The composition of claim 1 , wherein the first polypropylene comprises an isotactic polypropylene.

8. The composition of claim 1 , wherein the first polypropylene comprises a syndiotactic polypropylene.

9. 10. The composition of claim 1, wherein the first polypropylene further comprises, as polymerized monomers, up to 6 wt.% of the weight of the first polypropylene of one or more of ethylene, butene, pentene, hexene, or combinations thereof.

10. 10. The composition of claim 1, wherein the composition has a crystallinity of at least 25 wt%, based on the total weight of the first polypropylene, as measured by NMR.

11. The composition of claim 1 further comprising a foaming agent.

12. 10. The composition of claim 1 in the form of a masterbatch, wherein the alpha anti-nucleating agent and the beta-nucleating additive together comprise 0.1 to 80 wt. %, based on the total weight of the composition.

13. 1. A method for preparing an expandable polypropylene composition, comprising: a) compounding a first polypropylene comprising, as a polymerized monomer, at least 90 wt. % propylene based on the weight of the first polypropylene with an alpha anti-nucleating agent to form a polypropylene blend; b) compounding the polypropylene blend with a blowing agent to form a pre-annealed polypropylene composition; c) annealing the pre-annealed polypropylene composition at an annealing temperature Ta for an annealing time ta to form a foamable polypropylene composition; Including, The method, wherein the foamable polypropylene composition has a first melting peak T1 and a second melting peak T2 when measured by differential scanning calorimetry at a heating rate of 20°C / min.

14. 14. The method of claim 13, wherein the pre-annealed polypropylene composition has a third melting peak T3 as measured by differential scanning calorimetry at a heating rate of 20°C / min.

15. 14. The method of claim 13, wherein step a) further comprises compounding a beta-nucleating additive with the first polypropylene and the alpha anti-nucleating agent to form the polypropylene blend.

16. 16. The method of claim 15, wherein at least one of the beta-nucleating additive and the alpha-anti-nucleating agent is in the form of a masterbatch.

17. 14. The method of claim 13, wherein steps a) and b) are carried out in a single kneading operation.

18. 14. The method of claim 13, wherein step b) further comprises pelletizing the pre-annealed polypropylene composition.

19. 10. A method for preparing an expanded polypropylene composition, said method comprising heating the expandable polypropylene composition of claim 1 to an expansion temperature greater than T1 and less than T2.

20. 20. The method of claim 19, further comprising reducing the pressure to less than 1 atm during said heating.

Images