Linear polypropylene specimen and foam and process of preparing the same

Abstract

The present disclosure provides a process of preparing linear polypropylene foam, comprising the following steps: (a) preparing a specimen comprising at least one linear polypropylene; and at least one nucleating agent selected from the group consisting of alpha nucleating agents and beta nucleating agents; (b) deforming the specimen under a deforming pressure and at a deforming temperature for a period of time; and (c) subjecting the deformed specimen obtained in the step (b) to a foaming process to obtain the linear polypropylene foam. The present disclosure further provides a specimen after PIF treatment and a linear polypropylene foam prepared by the above process.

Claims

1. A process of preparing linear polypropylene foam, comprising the following steps: (a) preparing a specimen comprising at least one linear polypropylene; and at least one nucleating agent selected from the group consisting of alpha nucleating agents and beta nucleating agents; (b) deforming the specimen under a deforming pressure and at a deforming temperature for a period of time to obtain a deformed specimen; and (c) subjecting the deformed specimen obtained in the step (b) to a foaming process to obtain the linear polypropylene foam.

2. The process of claim 1, wherein the at least one linear polypropylene has a MFR ranging from 0.1 to 20 g/10 min.

3. The process of claim 1, wherein the at least one linear polypropylene has a MFR ranging from 1 to 15 g/10 min.

4. The process of claim 1, wherein the at least one linear polypropylene has a MFR ranging from 1.5 to 5 g/10 min.

5. The process of claim 1, wherein the at least one linear polypropylene is selected from homopolymers of propylene.

6. The process of claim 1, wherein the at least one linear polypropylene is selected from random copolymers of propylene.

7. The process of claim 1, wherein the at least one linear polypropylene is selected from impact copolymers of propylene.

8. The process of claim 1, wherein the at least one linear polypropylene is present in an amount of at least 80% by weight of the specimen.

9. The process of claim 1, wherein the specimen comprises the at least one linear polypropylene and at least one alpha nucleating agent; and the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the specimen.

10. The process of claim 1, wherein the specimen comprises the at least one linear polypropylene and at least one beta nucleating agent; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the specimen.

11. The process of claim 1, wherein the specimen comprises the at least one linear polypropylene, at least one alpha nucleating agent and at least one beta nucleating agent; the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the specimen; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the specimen.

12. The process of claim 1, wherein the at least one alpha nucleating agent is selected from 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol, bis(4-propylbenzylidene) propyl sorbitol, monovalent, bivalent, and trivalent 2,2-methylene-bis-(4,6-di-tertbutylphenyl) phosphate metal salts, sodium benzoate, 1,2-cyclohexanedicarboxylic acid, calcium salts, talc, and carbon nanotubes.

13. The process of claim 1, wherein the at least one beta nucleating agent is selected from aluminum salts of 6-quinazirin sulfonic acid, disodium salt of phthalic acid, isophthalic acid, terephthalic acid, NN-dicyclohexyl 2-6-naphthalene dicarboximide, and blends of organic dibasic acid and oxide, hydroxide, and acid of a Group II metal.

14. The process of claim 1, wherein an ultrasound treatment is further applied to the specimen to deform the specimen in the step (b).

15. A linear polypropylene specimen, comprising: at least one linear polypropylene; and at least one nucleating agent selected from the group consisting of alpha nucleating agents and beta nucleating agents, wherein the linear polypropylene specimen after PIF treatment has an Izod impact strength ranging from 40 kg-cm/cm to 100 kg-cm/cm.

16. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene has a MFR ranging from 0.1 to 20 g/10 min.

17. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene has a MFR ranging from 1 to 15 g/10 min.

18. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene has a MFR ranging from 1.5 to 5 g/10 min.

19. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene is selected from homopolymers of propylene.

20. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene is selected from random copolymers of propylene.

21. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene is selected from impact copolymers of propylene.

22. The linear polypropylene specimen of claim 15, wherein the at least one linear polypropylene is present in an amount of at least 80% by weight of the linear polypropylene specimen.

23. The linear polypropylene specimen of claim 15, wherein the linear polypropylene specimen comprises the at least one linear polypropylene and at least one alpha nucleating agent; and the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the linear polypropylene specimen.

24. The linear polypropylene specimen of claim 15, wherein the linear polypropylene specimen comprises the at least one linear polypropylene and at least one beta nucleating agent; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the linear polypropylene specimen.

25. The linear polypropylene specimen of claim 15, wherein the linear polypropylene specimen comprises the at least one linear polypropylene, at least one alpha nucleating agent and at least one beta nucleating agent; the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the linear polypropylene specimen; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the linear polypropylene specimen.

26. The linear polypropylene specimen of claim 15, wherein the at least one alpha nucleating agent is selected from 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol, bis(4-propylbenzylidene) propyl sorbitol, monovalent, bivalent, and trivalent 2,2-methylene-bis-(4,6-di-tertbutylphenyl) phosphate metal salts, sodium benzoate, 1,2-cyclohexanedicarboxylic acid, calcium salts, talc, and carbon nanotubes.

27. The linear polypropylene specimen of claim 15, wherein the at least one beta nucleating agent is selected from aluminum salts of 6-quinazirin sulfonic acid, disodium salt of phthalic acid, isophthalic acid, terephthalic acid, NN-dicyclohexyl 2-6-naphthalene dicarboximide, and blends of organic dibasic acid and oxide, hydroxide, and acid of a Group II metal.

28. A linear polypropylene foam, comprising: at least one linear polypropylene; and at least one nucleating agent selected from the group consisting of alpha nucleating agents and beta nucleating agents, wherein the linear polypropylene foam has an Izod impact strength ranging from 20 kg-cm/cm to 60 kg-cm/cm.

29. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene has a MFR ranging from 0.1 to 20 g/10 min.

30. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene has a MFR ranging from 1 to 15 g/10 min.

31. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene has a MFR ranging from 1.5 to 5 g/10 min.

32. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene is selected from homopolymers of propylene.

33. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene is selected from random copolymers of propylene.

34. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene is selected from impact copolymers of propylene.

35. The linear polypropylene foam of claim 28, wherein the at least one linear polypropylene is present in an amount of at least 80% by weight of the linear polypropylene foam.

36. The linear polypropylene foam of claim 28, wherein the linear polypropylene foam comprises the at least one linear polypropylene and at least one alpha nucleating agent; and the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the linear polypropylene foam.

37. The linear polypropylene foam of claim 28, wherein the linear polypropylene foam comprises the at least one linear polypropylene and at least one beta nucleating agent; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the linear polypropylene foam.

38. The linear polypropylene foam of claim 28, wherein the linear polypropylene foam comprises the at least one linear polypropylene, at least one alpha nucleating agent and at least one beta nucleating agent; the at least one alpha nucleating agent is present in an amount ranging from 0.01% to 5% by weight of the linear polypropylene foam; and the at least one beta nucleating agent is present in an amount ranging from 0.01% to 2% by weight of the linear polypropylene foam.

39. The linear polypropylene foam of claim 28, wherein the at least one alpha nucleating agent is selected from 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol, bis(4-propylbenzylidene) propyl sorbitol, monovalent, bivalent, and trivalent 2,2-methylene-bis-(4,6-di-tertbutylphenyl) phosphate metal salts, sodium benzoate, 1,2-cyclohexanedicarboxylic acid, calcium salts, talc, and carbon nanotubes.

40. The linear polypropylene foam of claim 28, wherein the at least one beta nucleating agent is selected from aluminum salts of 6-quinazirin sulfonic acid, disodium salt of phthalic acid, isophthalic acid, terephthalic acid, NN-dicyclohexyl 2-6-naphthalene dicarboximide, and blends of organic dibasic acid and oxide, hydroxide, and acid of a Group II metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] FIG. 1A is a perspective view showing a PIF apparatus used in examples of the present disclosure.

[0082] FIG. 1B is a perspective view showing PP samples before and after a PIF process.

[0083] FIG. 2 is a perspective view showing an exemplary system for making a linear polypropylene foam with a batch process.

[0084] FIG. 3A is a SEM photo of PP foam made from PIF-treated PC366-3 according to Example 2 of the present disclosure.

[0085] FIG. 3B is a SEM photo of WB140 PP cup according to Example 2 of the present disclosure.

[0086] FIG. 3C is a SEM photo of PP foam made from PIF-treated PC366-3 with 0.1 wt % nucleating agent according to Example 2 of the present disclosure.

[0087] FIG. 4A is a SEM photo of PP foam made from non-PIF treated 8001 with 0.1 wt % nucleating agent according to Example 2 of the present disclosure.

[0088] FIG. 4B shows SEM photos of PP foam made from PIF treated 8001 with 0.1 wt % nucleating agent according to Example 2 of the present disclosure.

[0089] FIG. 5A shows SEM photos of PP foam made from non-PIF treated PC366-3 0.1 wt % nucleating agent according to Example 2 of the present disclosure.

[0090] FIG. 5B shows SEM photos of PP foam made from PIF treated PC366-3 0.1 wt % nucleating agent according to Example 2 of the present disclosure.

[0091] FIG. 6 shows SEM photos of PP foam made from PIF treated 90% PC366-3 added with 0.1 wt % nucleating agent (NAB-82) and 10% ST611K according to Example 3 of the present disclosure.

[0092] FIG. 7 shows SEM photos of PP foam made from PIF treated PC366-3 according to Example 3 of the present disclosure.

[0093] FIG. 8 shows SEM photos of PP foam made from PIF treated ST611 () according to Example 3 of the present disclosure.

[0094] FIG. 9 shows SEM photos of PP foam made from PIF treated ST611K-T1 according to Example 3 of the present disclosure.

[0095] FIG. 10 is a SEM photo of PP foam made from non-PIF treated PC366-3 according to Example 4 of the present disclosure.

[0096] FIG. 11 is a SEM photo of PP foam made from PIF treated PC366-3 according to Example 4 of the present disclosure.

[0097] FIG. 12 is a SEM photo of PP foam made from PC366-3 added with 0.1% nucleating agent (NAB-82) according to Example 4 of the present disclosure.

[0098] FIG. 13 is a SEM photo of PP foam made from PIF treated 90% PC366-3 added with 0.1 wt % nucleating agent (NAB-82) and 10% ST611K according to Example 4 of the present disclosure.

[0099] FIG. 14 is a SEM photo of PP foam made from PIF treated PPCFoam-T14 according to Example 4 of the present disclosure.

[0100] FIG. 15 is a SEM photo of PP foam made from PIF treated ST611 () according to Example 4 of the present disclosure.

[0101] FIG. 16 is a SEM photo of PP foam made from PIF treated PT181PIF-T1 according to Example 4 of the present disclosure.

[0102] FIG. 17 is a SEM photo of PP foam made from PIF treated ST925 according to Example 4 of the present disclosure.

[0103] FIG. 18 is a DSC diagram of PP foam made from PC366-3 ().

[0104] FIG. 19 is a DSC diagram of PP foam made from PP composition with a nucleating agent content larger than nucleating agent.

[0105] FIG. 20 is a DSC diagram of PP foam made from PP composition with a nucleating agent content less than nucleating agent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0106] The present disclosure has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Analytical Methods

Foam Density

[0107] The mass densities of foamed polypropylene (PP foams) samples .sub.f were measured according to ASTM D792, wherein polymer foam is weighted in water using a sinker. .sub.f was calculated as follows:

[00002]${}_f=\frac{a}{a-b}.Math.{}_{\mathrm{water}}$

wherein a is the apparent mass of sample in air, b is the apparent mass of the sample completely immersed in water, and .sub.water is the density of water.

Scanning Electron Microscopy (SEM)

[0108] The morphologies of the obtained PP foams were detected by SEM (JEOL JSM-5600). The samples were immersed into liquid nitrogen for 30 min and then fractured. The fractured surfaces were sprayed with a layer of gold for further observation by SEM.

Differential Scanning Calorimetry (DSC)

[0109] A TA Q100 DSC was used to characterize the melting behavior of the obtained PP foams. Samples weighing approximately 6-10 mg were used for DSC characterization. The scanning range was ranged from 20 C. to 200 C. at a rate of 10 C./min.

Materials Used in the Following Examples

[0110] WB140: HMS-PP from Borealis.

[0111] Globalene PC366-3 (PC366-3, MFR of 3 g/10 min): homopolymer of propylene from LCY Chemical Corp.

[0112] Globalene ST611 (ST611, MFR of 1.8 g/10 min): a random copolymer of propylene from LCY Chemical Corp.

[0113] Globalene ST611K (ST611K): ST611 with alpha nucleating agent NX8000K.

[0114] ST611K-T1: ST611K with elastomer POE (Polyolefin elastomer from Dow Chemical).

[0115] ST611K-T2: ST611K with elastomer POE (Polyolefin elastomer from ExxonMobile).

[0116] Globalene PT181 (PT181, MFR of 0.4 g/10 min): homopolymer of propylene from LCY Chemical Corp.

[0117] PT181PIF-T1: PT181 modified with 8001 and specific / composition (MFR 0.53)

[0118] Globalene ST925 (ST925, MFR of 14 g/10 min): Random compolymer of propylene from LCY Chemical Corp.

[0119] Globalene 8001 (8001, MFR of 0.3 g/10 min): Random compolymer of propylene from LCY Chemical Corp.

[0120] NX8000K: Bis(4-propylbenzylidene) propyl sorbitol, which is a type of alpha nucleating agent from Milliken & Company.

[0121] NAB-82: calcium tetrahydrophthalate, which is a type of beta nucleating agent from Gchchem.

[0122] NA-11: sodium 2,2-methylene-bis-(4,6-di-t-butylphenylene) phosphate, which is a type of alpha nucleating agent

[0123] MB50-321: Lubricating agent from Dow Corning

[0124] MB50-001: Lubricating agent from Dow Corning

[0125] Irganox 1010: Antioxidant from BASF

[0126] Irgafos 168: Antioxidant from BASF

[0127] Hyperform HPN-20E: HPN-20E, Calcium salt of 1,2-cyclo-hexanedicarboxylic acid from Milliken & Company.

[0128] CO.sub.2 with a purity of 99.99% was used as a blowing agent.

Example 1Evaluating Parameters in PIF Process

[0129] Before the PIF process, polypropylene with or without nucleating agents were first mixed in a high speed Henschel mixer for 30-60 seconds. The mixtures (10 kg each) were then put into the hopper of a co-rotating twin screw extruder (L/D: 37, KM Berstorff ZE40A) with a temperature setting of 160-200 C. and a screw rotational speed of 260-300 rpm. The extruded polymer composition was then molded through a die and then cooled in a tank with water circulation to obtain polymer strands. After water was removed, the strands were cut by a pelletizer, and the pellets were further screened with a classifier to get the final pellets (i.e. the polymer composition of the present disclosure).

[0130] Polymer compositions after molding are to be treated with PIF process were placed in the cavity of the apparatus shown in FIG. 1A.

[0131] FIG. 1A is a perspective view showing a PIF apparatus used in the present disclosure. The PIF apparatus used in the present disclosure mainly comprises: a mold 11 with a cavity 111; and a plunger 13 having a size approximately identical to the size of the cavity 111. During the PIF process, the sample 3 was placed in the cavity 111, followed by heated and pressed by the plunger 13; and then, the sample 3 was deformed, flowed in the flow direction (FD), constrained in the constraint direction (CD) and compressed in the load direction (LD). FIG. 1B is a perspective view showing samples before and after the PIF process. The sample 3 before the PIF process has a cube shape; but the present disclosure is not limited thereto. After the PIF process, the sample 3 is pressed and become a sheet 3. In the present example and the following examples, the cavity 111 has a size of 1353 mm.sup.3 or 165133 mm.sup.3; but the present disclosure is not limited thereto.

[0132] The PIF process held in the present example and the following examples are briefly described below.

[0133] First, the plastic pellets or powders are injection molding or compression molding into a typical specimen (for example, the sample 3 shown in FIG. 1B). Next, the specimen is then put into a compression mold (for example, the PIF apparatus shown in FIG. 1A). After introducing suitable pressure and temperature under a setting time, the specimens is fully compressed and elongated to fit the cavity. The compressed specimen (for example, the sheet 3 shown in FIG. 1B) is then used for physical properties analysis and afterwards foaming process.

[0134] In the present example, the specimen is pre-heated in an oven at 130145 C. for 515 min, compressed and elongated at 130155 C. and 4703000 psi for 10 sec, and then cooled. The cooling conditions can be held by minimizing compression pressure (hereinafter, min. compression pressure) or natural cooling to room temperature.

[0135] In the present example, PC366-3 with 0.1 wt % nucleating agent (NAB-82) was used as the polymer composition to identify the processing window of the PIF process. The results are shown in the following Table 1.

TABLE-US-00001 TABLE 1 Pre-heating PIF process Temp Time Temp Pressure Density Item ( C.) (min) ( C.) (psi) Cooling process (g/cm.sup.3) 1-1 130 10 155 3000 Natural cooling 0.633 1-2 135 10 155 3000 Natural cooling 0.621 1-3 140 10 155 3000 Natural cooling 0.624 1-4 145 10 155 3000 Min. compression 0.487 pressure 1-5 145 10 155 3000 Natural cooling 0.448 1-6 145 10 155 470 Natural cooling 0.188 1-7 145 5 155 470 Natural cooling 0.174 1-8 135 10 155 470 Natural cooling 0.218 1-9 140 10 155 1000 Natural cooling 0.710 1-10 145 10 155 1000 Natural cooling 0.682 1-11 150 10 155 1000 Natural cooling 0.372 1-12 155 10 155 1000 Natural cooling 0.385 1-13 130 10 155 600 Natural cooling 0.292 1-14 135 10 155 600 Natural cooling 0.426 1-15 140 10 155 600 Natural cooling 0.402 1-16 145 10 155 600 Natural cooling 0.343 1-17 150 10 155 600 Natural cooling 0.168 1-18 155 10 155 600 Natural cooling 0.230 1-19 130 10 155 800 Natural cooling 0.628 1-20 135 10 155 800 Natural cooling 0.666 1-21 140 10 155 800 Natural cooling 0.601 1-22 145 10 155 800 Natural cooling 0.249 1-23 150 10 155 800 Natural cooling 0.388 1-24 155 10 155 800 Natural cooling 0.189

[0136] As shown in Items 1-4 and 1-5, the densities of the samples cooled by minimizing compression pressure or natural cooling to room temperature are similar. Hence, according to the results shown in Table 1, the optimal PIF processing window can be identified as follow.

[0137] Temperature: [0138] Homopolymer and heterophasic (impact) copolymer PP: 145155 C. [0139] Random copolymer PP: 135145 C. [0140] Gauge pressure: 470800 psi [0141] Compression time: 1030 sec [0142] Cooling mode: Natural cooling

Example 2Comparing Samples Treated with and without PIF Process

[0143] The PIF-treated and non-PIF treated specimens were batch foamed using a high-pressure autoclave. After placing the specimens in a high pressure vessel, CO.sub.2 was injected into the vessel. After the samples were saturated with CO.sub.2 at set temperature and 2050 psi for 30 min, an instant depressurization (<3 sec) was applied to achieve PP foaming. All samples were foamed with supercritical CO.sub.2. Herein, the foaming temperature for 8001 is 135-145 C., and the foaming temperature for PC366-3 is 145-155 C.

[0144] Herein, a WB140 PP cup, in which WB140 is commercialized HMSPP from Borealis AG, is used as a comparison example. The density of the WB140 PP cup is 0.29 g/cm.sup.3; and the cell size of the cells thereof is not uniform.

[0145] In the present example, as shown in FIGS. 3A and 3B, the PP foam made from PIF-treated PC366-3 has a density of 0.062 g/cm.sup.3; and the cell size of the cells thereof is more uniform than the cell size of the cells of WB140. In addition, the PP foam made from PIF-treated PC366-3 with 0.1 wt % nucleating agent (NAB-82) has a density of 0.077 g/cm.sup.3, as shown in FIG. 3C; and the cell size of the cells thereof is more uniform than the cell size of the PP foam made from PIF-treated PC366-3 without nucleating agent.

[0146] Furthermore, the PP foam made from PIF-treated and non-PIF treated 8001 with 0.1 wt % a nucleating agent (HPN-20E) were compared. After SEM analysis, the PP foam made from non-PIF treated 8001 with 0.1 wt % nucleating agent has fragile structure (as shown in FIG. 4A), and the structure is distorted after vacuum drawing during gold-plating on the sample. On the other hand, the PP foam made from PIF treated 8001 with 0.1 wt % nucleating agent has stiff structure, and has uniform cells after vacuum drawing during gold-plating on the sample (as shown in FIG. 4B).

[0147] Additionally, the PP foam made from PIF-treated and non-PIF treated PC366-3 with 0.1 wt % nucleating agent (NAB-82) were also compared. After SEM analysis, as shown in FIGS. 5A and 5B, the PP foam made from PIF treated PC366-3 0.1 wt % nucleating agent (NAB-82) has more uniform and stiff cell structure than the PP foam made from non-PIF treated PC366-3 0.1 wt % nucleating agent (NAB-82).

Example 3Small-Scale Foaming

[0148] In the present example, specimens were pre-heated at 140 C. for 10 min, treated with the PIF process at the conditions listed in the following Table 2, and then cooled through natural cooling.

[0149] The types of the polymer compositions, the PIF conditions used in the present example, and the physical properties of the PIF treated specimens are listed in the following Table 2.

TABLE-US-00002 TABLE 2 Izod impact Tensile strength PIF process strength (23 C.) Sample Polymer Temp Pressure Time (kg/ (kg-cm/ items composition ( C.) (psi) (sec) cm.sup.2) cm) Spacer1 mm*.sup.a 2-1 ST611 () *.sup.b 135 470 10 83.6 11.5 2-2 ST611K-T1 135 470 10 84.5 54.8 2-3 ST611K-T2 135 470 10 178 50.0 2-4 90% PC366-3 () *.sup.c 150 470 10 343.3 97.8 10% ST611K 2-5 PC366-3 150 470 10 294.7 38.8 Spacer2 mm*.sup.a 2-6 ST611 () *.sup.b 135 470 10 90.2 11.9 2-7 ST611K-T1 135 470 10 134.3 48.2 2-8 ST611K-T2 135 470 10 169.9 42.4 2-9 90% PC366-3 () *.sup.c 150 470 10 343.4 91.2 10% ST611K 2-10 PC366-3 150 470 10 292.9 31.6 2-11 8001 135 470 10 *.sup.aA spacer having thickness of 1 mm or 2 mm was put in the cavity 111 of the PIF apparatus shown in FIG. 1A. .sup.*b: ST611 () refers to a polymer composition comprising ST611 with 0.1 wt % nucleating agent (NAB-82). .sup.*c: PC366-3 () refers to a polymer composition comprising PC366-3 with 0.1 wt % nucleating agent (NAB-82).

[0150] Compared to the non-PIF treated PC366-3, which has the Izod impact strength of around 3 kg-cm/cm, all the PIF treated polymer compositions listed in the above Table 2 have better Izod impact strengths. This result indicates the PIF process can enhance the impact strength of the polymer compositions.

[0151] The PIF-treated samples listed in the above Table 2 were then treated with the batch foaming process with different conditions. The process of the batch foaming process used in the present example is similar to that shown in Example 2, except the conditions of the batch foaming process. The conditions of the foaming process and the densities of the obtained PP foam are listed in the following Table 3, wherein the identical sample items listed in Tables 2 and 3 refer to the same polymer compositions.

TABLE-US-00003 TABLE 3 Sample Batch foaming process Density items Temp ( C.) Pressure (psi) Time (min) (g/cm.sup.3) 2-4 155 2050 30 0.025 2-9 0.021 2-5 0.036 2-10 0.033 2-4 155 2050 10 0.038 2-9 0.051 2-5 0.061 2-10 0.067 2-1 145 2050 30 Melted 2-2 0.039 2-3 0.058 2-6 Melted 2-1 140 2050 30 0.036 2-2 0.044 2-3 0.045 2-6 0.036 2-1 140 2050 10 0.063 2-2 0.075 2-3 0.080 2-6 0.068 2-7 140 2050 30 0.045 2-8 0.047 2-11 0.037

[0152] As shown in Table 3, when the PIF-treated specimens are foamed, PP foams with low densities can be obtained. By controlling the temperature of the foaming conditions, the melting of the specimens can be prevented.

[0153] FIGS. 6 to 9 show different PP foams made from specimens with different formulations. When the specimen is treated with PIF process first, even though the PP contained in the polymer composition has low MFR (for example, PP 8001 (Item 2-11) having MFR of 0.3 g/10 min), PP foams with low density still can be obtained. Furthermore, the PP foam made from the polymer composition of 90% PC366-3 added with 0.1 wt % nucleating agent (NAB-82) and 10% ST611K (contain NX8000K) has the most uniform cells and the best impact strength.

Example 4Large-Scale Foaming

[0154] In the present example, small and large specimens of the PP polymer compositions were tested, wherein the size of the small specimens is 13 mm5 mm2 mm, and the size of the large specimens is the specimen of tensile strength (165 mm13 mm2 mm). The types of the polymer compositions, the PIF and foaming conditions used in the present example, and the density of the obtained foams are listed in the following Table 4.

TABLE-US-00004 TABLE 4 PIF process Batch foaming process Polymer Temp Pressure Time Temp Pressure Time Density Items composition Size*.sup.d ( C.) (psi) (sec) ( C.) (psi) (sec) (g/cm.sup.3) 4-1 PC366-3 Small 160 2050 30 0.032 4-2 Small 150 470 10 160 2050 30 0.042 4-3 Large 160 2050 30 0.245 4-4 Large 150 470 10 160 2050 30 0.061 4-5 PC366-3 ()*.sup.e Small 160 2050 30 0.022 4-6 Small 150 470 10 160 2050 30 0.041 4-7 Large 150 470 10 160 2050 30 0.035 4-8 90% PC366-3 Small 160 2050 30 0.024 4-9 () Small 4-10 10% ST611K Large 160 2050 30 0.041 4-11 ST611 ()*.sup.f Small 140 2050 30 0.044 4-12 Small 4-13 Large 135 470 10 140 2050 30 0.032 4-14 PPCFoam-T14*.sup.g Small 160 2050 30 0.032 4-15 Small 4-16 Large 160 2050 30 0.041 4-17 PT181PIF-T1 Small 160 2050 30 0.083 4-18 Small 150 470 10 160 2050 30 0.023 4-19 Large 150 470 10 160 2050 30 0.039 4-20 ST925 Small 145 2050 30 0.032 4-21 Small 135 470 10 145 2050 30 0.036 4-22 Large 135 470 10 145 2050 30 0.04 *.sup.dThe term size herein refers to small or large specimens. *.sup.ePC366-3 () refers to a polymer composition comprising PC366-3 with 0.1 wt % nucleating agent (NAB-82). *.sup.fST611 () refers to a polymer composition comprising ST611 with 0.1 wt % nucleating agent (NAB-82). *.sup.gPPCFoam-T14 refers to a polymer composition comprising 90 wt % PC366-3, 10 wt % ST611, 0.05 wt % nucleating agent (NX8000K) and 0.2 wt % nucleating agent (NAB-82).

[0155] FIGS. 10 to 17 show different PP foams made from specimens with different formulations.

[0156] As shown in Table 4, when the specimens were treated with PIF process first, the obtained PP foams can have low density. For example, comparing the large specimens of PC366-3 treated with or without PIF process (as shown in FIGS. 10 and 11), the density of the PIF treated PP foam is much lower than that of the non-PIF treated PP foam. Hence, the PIF process indeed can facilitate to form PP foam with uniform cells and low density.

[0157] In addition, the DSC diagrams of three composite formulations which contain only or with nucleating agents are shown in FIGS. 18 to 20. There are two melting peaks shown in the diagram of FIG. 18 when only adds nucleating agent in the formulation. Interestingly, when the amount of nucleating agent is higher or equal to the amount of nucleating agent, as shown in FIG. 20, there are still two melting peaks ( and crystals) clearly shown in the DSC diagram. On the other hand, when the amount of nucleating agent is less than the amount of nucleating agent, as shown in FIG. 19, only one melting peak (for crystal) shows up in the DSC diagram. Nevertheless, all the cell density and expansion ratio of the three composite formulations are very comparable. The difference will be discerned in the physical properties before and after foaming.

[0158] From the results shown in the aforementioned examples, the PP foam made from the polymer composition containing 90 wt % PC366-3 (added with 1 wt % nucleating agent) and 10 wt % ST611K (contains NX8000K) has homogeneous and small cell size distribution and also has lower density. The non-foamed specimens treated with the PIF process have relatively higher tensile strength and impact strength than the non-foamed specimen without PIF treatment.

[0159] In addition, the cell sizes of the PP foams made from the PIF-treated polymer compositions ST611 added with nucleating agent (2030 m) and ST611K-T1 (1020 m) are smaller than the cell sizes of the PP foams made from other formulations. Hence, these PP foams can be used in certain applications that need to absorb energy in high cushion.

[0160] Furthermore, the stiffness of the PP foam made from the PIF treated polymer composition is quite better than that of the PP foam made from the non-PIF treated polymer composition.

Example 5Batch Foaming Process

[0161] In the present example, specimens of the PP polymer compositions were tested, wherein the size of the small specimens is 60 mm60 mm2.3 mm. The components of the polymer compositions are listed in the following Table 5.

TABLE-US-00005 TABLE 5 PP polymer composition Components in the PP polymer composition PPCFoam-T11 WB140 + 2 wt % talc + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 PC366-3 ( + ) PC366-3 + 0.1 wt % NAB-82 + 0.05 wt % NA11 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 ST611 ( + ) ST611 + 0.1 wt % NAB-82 + 0.05 wt % NA11 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 PPCFoam-T17 PC366-3 + 10 wt % ST611 + 0.1 wt % NAB-82 + 0.05 wt % NX8000K + 1 wt % MB50-321 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 PPCFoam-T24 S'I'925 + 5 wt % ST611 + 0.1 wt % NAB-82 + 0.05 wt % NX8000K + 0.5 wt % MB50-001 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 PPCFoam-T27 PC366-3 + 10 wt % ST611 + 0.1 wt % NAB-82 + 0.05 wt % NX8000K + 0.5 wt % MB50-001 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 PPCFoam-T33 ST925 + 5 wt % sT611 + 0.1 wt % NAB-82 + 0.05 wt % NX8000K + 0.5 wt % MB50-001 + 0.1 wt % Irganox 1010 + 0.1 wt % Irgafos 168 + 2% talc HTP-05

[0162] The foaming conditions used in the present example, and the density, the tensile strength and the elongation at break of the obtained foams are listed in the following Table 6. Herein, the blowing agent used in the foaming process is supercritical CO.sub.2. Furthermore, the density of the obtained foams were measured by ASTM D1622, the tensile strength thereof were measured by IS0 1798:2008, and the elongation at break thereof were measured by IS0 1798:2008. In addition, all the specimens were placed at 23 C. and 65% RH for at least 24 hours before testing.

TABLE-US-00006 TABLE 6 Tensile Elongation PP polymer Foaming Density strength at break Items composition conditions (g/cm.sup.3) (kPa) (%) 6-1 PPCFoam-T11 155 C./2050 psi/ 0.375 30 min 6-2 PC366-3 160 C./2050 psi/ 0.025 644 16.97 ( + ) 30 min 6-3 PC366-3 155 C./2050 psi/ 0.043 970 10.80 ( + ) 30 min 6-4 ST611 ( + ) 130 C./2050 psi/ 0.053 1580 28.30 30 min 6-5 ST611 ( + ) 135 C./2050 psi/ 0.059 2763 26.90 30 min 6-6 PPCFoam-T17 155 C./2050 psi/ 0.032 742 14.75 30 min 6-7 PPCFoam-T24 145 C./2050 psi/ 0.037 475 20.35 30 min 6-8 PPCFoam-T24 145 C./2050 psi/ 0.027 795 13.18 15 min 6-9 PPCFoam-T27 155 C./2050 psi/ 0.037 1325 17.60 30 min 6-10 PPCFoam-T33 130 C./2050 psi/ 0.061 2127 34.50 30 min 6-11 EPP beads 0.02 300 22 Foam (BASF) 6-12 EPP beads 0.03 430 21 Foam (BASF) 6-13 EPP beads 0.04 550 19 Foam (BASF) 6-14 EPP beads 0.05 650 18 Foam (BASF) 6-15 EPP beads 0.06 760 17 Foam (BASF)

[0163] The physical properties of PP foams made from the polymer compositions listed in Table 5 via the batch physical foaming process (i.e. Items 6-2 to 6-10) are compared to that made by WB140 (i.e. Item 6-1) and EPP beads foam (BASF NEOPOLEN) (i.e. Items 6-11 to 6-15). Basically, the tensile strength of all PP foams made from the polymer compositions of the present disclosure (i.e. Items 6-2 to 6-10) is higher than the commercial EPP beads foam (i.e. Items 6-11 to 6-15) at the similar density range. However, the elongation at break of some PP foams made from the polymer compositions of the present disclosure at certain foaming temperature is not as good as the commercial EPP beads foam; but this can be overcome by adjusting the foaming temperature and residence time to get balance of the properties between tensile strength and elongation at break.

[0164] Furthermore, the specimens of the PP polymer compositions were treated with PIF process, followed by the foaming process. The PIF and foaming conditions used in the present example, and the density, the tensile strength and the elongation at break of the obtained foams are listed in the following Table 7. Herein, the blowing agent used in the foaming process is supercritical CO.sub.2. Furthermore, the density of the obtained foams were measured by ASTM D1622, the tensile strength thereof were measured by IS0 1798:2008, and the elongation at break thereof were measured by IS0 1798:2008. In addition, all the specimens were placed at 23 C. and 65% RH for at least 24 hours before testing.

TABLE-US-00007 TABLE 7 Tensile Elongation PP polymer Density strength at break Items composition PIF conditions Foaming conditions (g/cm.sup.3) (kPa) (%) 7-1 PPCFoam-T11 1.55 C./2050 psi/30 min 0.236 7-2 PPCFoam-T17 150 C./470 psi/10 sec 155 C./2050 psi/30 min 0.038 1108 26.45 7-3 PPCFoam-T24 150 C./470 psi/10 sec 145 C./2050 psi/30 min 0.036 1029 36.92 7-4 PPCFoam-T27 150 C./470 psi/10 sec 155 C./2050 psi/30 min 0.045 1590 40.05 7-5 PPCFoam-T33 140 C./470 psi/10 sec 130 C./2050 psi/30 min 0.052 2748 34.45 7-6 EPP beads 0.03 430 21 Foam (BASF) 7-7 EPP beads 0.04 550 19 Foam (BASF) 7-8 EPP beads 0.05 650 18 Foam (BASF)

[0165] The physical properties of PP foams made from the PIF treated polymer compositions listed in Table 5 (i.e. Items 7-2 to 7-5) are compared to those made by WB140 (i.e. Item 7-1) and EPP beads foam (BASF NEOPOLEN) (i.e. Items 7-6 to 7-8), and the comparison results are shown in Table 7. The results shown in Table 7 indicate that the PP foams made from the PIF-treated polymer compositions of the present disclosure (i.e. Items 7-2 to 7-5) have improved tensile strength and elongation at break compared to those made from WB140 (i.e. Item 7-1) and EPP beads foam (BASF NEOPOLEN) (i.e. Items 7-6 to 7-8). In addition, by comparing the results shown in Tables 6 and 7, when the PP foams made from the polymer compositions of the present disclosure are treated with the PIF process first followed by the batch physical foaming process (i.e. Items 7-2 to 7-5), the tensile strength and elongation at break of the PP foams made from the PIF-treated polymer compositions (i.e. Items 7-2 to 7-5) are better than the PP foams made from the non PIF-treated polymer compositions (i.e. Items 6-6 to 6-10).

[0166] From the results shown in the present example, it can be concluded that when the PP polymer compositions of the present disclosure are treated with the PIF process first, the obtained PP foams after the foaming process have improved both tensile strength and elongation at break. Therefore, the applications of the obtained PP foams can further be extended.

[0167] Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.