Impact modifier composition

Abstract

An impact modifier composition (IMC) comprising (a) a polyolefin plastomer (POP) and (b) at least one block copolymer is disclosed. The density of the POP is 0.870-0.920 g / cm < 3 >, the MFI (melt flow index) is 0.5-30 g / 10 min under the condition of 190 DEG C / 2.16 kg, the melt index ratio is 10-22, and the long chain branching (LCB) lt is 10-22; and 15 LCB / 10 < 6 > carbon. The at least one block copolymer is selected from the group consisting of (i) a first hydrogenated styrenic block copolymer (first HSBC), (ii) a second hydrogenated styrenic block copolymer (second HSBC), and (iii) at least one multi-arm block copolymer. Each of the first HSBC and the second HSBC has a polystyrene content (PSC) of 3 to 20 wt% and 15 to 30 wt%, respectively. The impact modifier composition can be used in polyolefin compositions to improve a balance of impact resistance and other mechanical properties.

Description

Technical Field

[0001] The present disclosure relates to impact modifier compositions, methods for preparing the same, and uses thereof. Background Art

[0002] Various impact modifier compositions have been used to improve the mechanical properties of polymer compositions, particularly compositions based on polyolefins. Compositions based on polyolefins such as polypropylene have many applications, including packaging materials, machine parts, automotive parts, electrical components, etc. In order to improve the impact resistance of polypropylene compositions, elastomers and / or rubber impact modifier compositions have been attempted. Such impact modifier compositions absorb or dissipate impact energy, and can be added as an additive by polymerization in a reactor or in a compounding step. Impact modifier compositions help to compensate for the inherent brittleness of polypropylene, the embrittlement, notch sensitivity and crack propagation that occur at subzero temperatures.

[0003] In order to improve the impact resistance of polypropylene compositions while still balancing other desired properties, impact modifiers based on styrenic block copolymers or polyolefin plastomers have been tried. By adding rubber materials or other types of impact modifiers, the impact resistance of polypropylene compositions is achieved along with reduced stiffness, fluidity, transparency, etc.

[0004] There remains a need for improved impact modifier compositions for polyolefin compositions to increase impact resistance while maintaining a good balance of other mechanical properties. SUMMARY OF THE INVENTION

[0006] In one aspect, the present disclosure relates to an impact modifier composition (IMC) comprising, consisting essentially of, or consisting of: (a) 50-97 wt% of a polyolefin plastomer (POP) and (b) 3-50 wt% of at least one block copolymer. The POP has a POP of 0.870-0.920 g / cm2 as measured according to ASTM D1505. 3 density, a melt flow index of 0.5-30 g / 10 min measured at 190° C. and 2.16 kg load according to ASTM D1238, a melt index ratio (MFI) of 10-22 measured as described in the specification, and <15 LCB / 10 6The at least one block copolymer is selected from: (i) a first hydrogenated styrenic block copolymer (first HSBC) having block A and block B, (ii) a second hydrogenated styrenic block copolymer (second HSBC) having block A' and block B', and (iii) at least one multi-arm block copolymer (MABC). Prior to hydrogenation, each block A and A' is independently a polymer block of a vinyl aromatic monomer, and each block B and B' is a polymer block of a conjugated diene monomer. The first HSBC has a polystyrene content (PSC) of 3-20 wt% and block B has a vinyl content of 0-60 wt%. The second HSBC has a PSC of 15-30 wt% and a vinyl content of 60-90 wt%. The MABC is selected from (iiia) having the general formula I: (EP) n The coupled hydrogenated polyisoprene arms of X, (iiib) have the general formula II: (EB) n X is a coupled hydrogenated polybutadiene arm, and mixtures thereof, wherein X is the residue of a coupling agent and n is 3-10.

[0007] In a second aspect, the POP has a 0.01-10 LCB / 10 6 LCB of carbon.

[0008] In a third aspect, the at least one block copolymer is a first HSBC wherein block A has a molecular weight (Mp) of 1-40 kg / mol, block B has a vinyl content of 0-50 wt%, a PSC of 4-15 wt% and the molecular weight (Mp) of the first HSBC is 20-300 kg / mol.

[0009] In a fourth aspect, the at least one block copolymer is a second HSBC wherein block A' has a molecular weight (Mp) of 1-40 kg / mol, block B' has a vinyl content of 70-85 wt%, a PSC of 15-25 wt% and a molecular weight (Mp) of 20-300 kg / mol.

[0010] In a fifth aspect, the at least one block copolymer is MABC, wherein the MFR measured according to ASTM D1238 at 200°C and 5 kg load is 3-30, the coupling efficiency is >90%, the residual unsaturation is 0.01-1 meq / g and the molecular weight (Mp) is 300-700 kg / mol. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following terms will be used throughout this specification.

[0013] “Consisting essentially of…” means that the claimed composition mainly comprises the specified material substance, and is allowed to contain additional components that do not substantially affect the new characteristics or functions of the claimed invention. If present, the amount of the additional components is <30%, or <20%, or <10%.

[0014] "At least one of [A, B, and C]" or "any one of [A, B, and C]" refers to a single member thereof, more than one member thereof, or a combination of members thereof. For example, at least one of A, B, and C includes, for example, only A, only B, or only C, as well as any other combinations of A and B, A and C, B and C, or A, B and C, or A, B, and C. In other examples, at least one of A and B means only A, only B, and A and B.

[0015] Embodiments presented as "A, B, or C" should be interpreted to include only A, only B, only C, "A or B", "A or C", "B or C", or "A, B, or C".

[0016] "Any one of A, B or C" means one of the options A, B or C.

[0017] "Any one of A, B and C" means one or more options among A, B and C.

[0018] The "polystyrene content" or PSC of a block copolymer refers to the weight percent of polymerized vinyl aromatic monomer (e.g., styrene) in the block copolymer, calculated by dividing the sum of the molecular weights of all vinyl aromatic units by the total molecular weight of the block copolymer. PSC can be determined using any suitable method, such as proton nuclear magnetic resonance (NMR).

[0019] "Vinyl content" refers to the content of conjugated diene monomers polymerized by 1,2-addition in the case of butadiene or by 3,4-addition in the case of isoprene (thus producing a monosubstituted olefin or vinyl group adjacent to the polymer backbone). Vinyl content can be determined by nuclear magnetic resonance spectroscopy (NMR).

[0020] "Molecular weight" or Mw refers to the polystyrene equivalent molecular weight of a polymer block or block copolymer, in kg / mol. Mw can be determined by gel permeation chromatography (GPC) using polystyrene calibration standards, for example, according to ASTM5296-19. The GPC detector can be an ultraviolet or refractive index detector or a combination thereof. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The Mw of a polymer determined using a GPC so calibrated is the polystyrene equivalent molecular weight or apparent molecular weight. The Mw shown herein is measured at the peak of the GPC trace, commonly referred to as the polystyrene equivalent "peak molecular weight", expressed as M p .

[0021] A "bimodal" molecular weight of a polymer refers to two or more peaks of different molecular weights that are readily discernible in a plot of (x) molecular weight as a function of (y) relative proportion of polymer showing a given molecular weight, such as obtained by gel permeation chromatography (GPC) analysis of the polymer.

[0022] "Alpha olefins" or "α-olefins" refer to olefins of the formula C n H 2n An olefin or alkenyl characterized by having a double bond in the primary or alpha position. Examples of alpha-olefins include ethylene, propylene, 1-butene, 1-pentene, and the like.

[0023] "Long chain branching" or LCB refers to the presence of side chains or branches extending along the polymer backbone, as measured by GPC and / or NMR techniques and expressed as the number of LCBs per 1,000,000 carbons, LCB / 10 6 A carbon.

[0024] "Short chain branching" or SCB refers to the presence of shorter side chains or branches attached to the polymer backbone. These branches consist of a smaller number of repeating units compared to the polymer backbone. SCB occurs when a comonomer such as 1-butene is copolymerized with a primary olefin monomer such as ethylene. The comonomer units disrupt the regularity of the polymer backbone, introducing branches at relatively regular intervals. The main difference between LCB and SCB is that in LCB, the long chain branches consist of multiple repeating units and are relatively long, such as more than a few dozen (>36) to several thousand repeating units in length, where the "several" in several dozen means 3 units. In contrast, in SCB, the short chain branches are shorter in length or have a smaller number of repeating units, such as a few to a few dozen (e.g., 2, 5, 10, 20, 30, <36) repeating units. SCB is measured using the GPC-IR method.

[0025] "Melt Index Ratio" or MIR refers to the ratio of the melt flow index (MFI) of a polymer measured at 190°C and two different loads (ie, 21.6 kg and 2.16 kg), calculated as follows:

[0026] MIR = (MFI at 21.6 kg) / (MFI at 2.16 kg) (I)

[0027] The present disclosure relates to an impact modifier composition (IMC) comprising: (a) a polyolefin plastomer (POP) and (b) at least one block copolymer selected from: (i) a first hydrogenated styrenic block copolymer (first HSBC), (ii) a second hydrogenated styrenic block copolymer (second HSBC), and (iii) a multi-arm block copolymer (MABC). The IMC can be used in polyolefin compositions to improve a good balance of impact resistance and other mechanical properties (e.g., high stiffness, tensile strength, flow properties, etc.).

[0028] Polyolefin plastomers (POP)

[0029] In some embodiments, the POP is prepared in a polymerization process from ethylene and one or more C 3-20 Ethylene copolymers obtained from α-olefin comonomers and / or dienes.

[0030] Examples of comonomers include unsubstituted or substituted with up to two C 1-6 Alkyl substituted C 3-12 α-olefins, unsubstituted or substituted with up to two substituents selected from the following C 5-12 Vinyl aromatic monomer: C 1-4 Alkyl, with C 1-4 Alkyl substituted C 4-12 Examples of such α-olefins include propylene, isobutylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof.

[0031] In some embodiments, the POP comprises 1-60, or 10-50, or 10-45, or 5-50, or 10-40 wt % of comonomer, based on the total weight of the POP, with the remainder being ethylene monomer.

[0032] In some embodiments, POP is blended with other polymers / copolymers including low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE), and mixtures thereof. Based on the total weight of POP, such polymers / copolymers may be 0.1-99, or 1-50, or 1-25, or 10-90, or 50-99, or 75-95 wt%.

[0033] In some embodiments, the POP has a value of ≤ 0.920, or < 0.915, or < 0.910, or < 0.905, or 0.870-0.920, or 0.875-0.915, or 0.880-0.910, or 0.870-0.910, or 0.870-0.905 g / cm2 as measured according to ASTM D1505. 3 density.

[0034] In some embodiments, the number average molecular weight (Mn) of the POP is 10-150, or 15-130, or 20-100, or 10-80, or 25-110 kg / mol.

[0035] In some embodiments, the weight average molecular weight (Mw) of the POP is 20-200, or 30-180, or 35-160, or 40-150, or 45-140, or 20-140, or 45-160 kg / mol.

[0036] In some embodiments, the polydispersity index (PDI) of the POPs is 1.5-4.5, or 1.8-4.2, or 2.0-4.0, or 2-4.5, or 2.2-3.5.

[0037] In some embodiments, the POP comprises two copolymer fractions POP-1 and POP-2 in a certain amount (e.g., 1:10-10:1 or 1:5-5:1). In some embodiments, the POP exhibits a bimodal molecular weight distribution and has a weight ratio (MW) of the weight average molecular weight of the high molecular weight (HMW) fraction to the weight average molecular weight of the low molecular weight (LMW) fraction of 20-60, or 25-50, or 30-40. w-HMW / M w-LMW Compare).

[0038] In some embodiments, the POP has single, double or multiple melting peaks between -30°C and 130°C, or -20°C to at least 140°C, or -10°C to 130°C, or 0-130°C or 20-130°C, as measured by DSC according to ASTM D3418.

[0039] In some embodiments, the POP has a melt flow index (MFI) of 0.5-30, or 1-25, or 0.5-20, or 1-15, or 1-10, or 3-12, or 4-10 g / 10 min, measured according to ASTM 1238 at 190°C and 2.16 kg load.

[0040] In some embodiments, the POP has a melt flow index (MFI) of 7-900, or 15-750, or 7-600, or 15-450, or 15-300, or 20-200 g / 10 min, measured according to ASTM 1238 at 190°C and 21.6 kg load.

[0041] In some embodiments, the POP has a melt index ratio (MIR) of 10-22, or 11-21, or 12-20, or 15-20.

[0042] In some embodiments, the long chain branching (LCB) of the POP is <15 LCB / 10 6 Carbon, or <10LCB / 10 6 Carbon, or <5LCB / 10 6 carbon, or <3LCB / 10 6 carbon, or <2LCB / 10 6 Carbon, or 0.01-10LCB / 10 6 Carbon, or 0.05-5LCB / 10 6 Carbon, or 0.1-3LCB / 10 6 Carbon, or 0.01-2LCB / 10 6 Carbon, or 0.05-1.9LCB / 10 6 Carbon, or 0.1-1.8LCB / 10 6 Carbon, or 0.5-2LCB / 10 6 Carbon, or 0.7-1.7LCB / 10 6 Carbon, measured according to the Janzen-ColbyPlot method. The term "10 6 The "carbon" includes main chain and branch chain carbon.

[0043] In some embodiments, the POP has a short chain branching (SCB) degree of <15, or <30, or <40 wt%, based on the total weight of the POP. Alternatively, the POP may have no measurable high density polymer fraction, for example, no high density polymer fraction having a density ≥0.940 g / cm2 as determined by temperature rising elution fractionation (TREF) techniques and infrared or 13C nuclear magnetic resonance (NMR) analysis. 3 of fractions.

[0044] In some embodiments, the POP has a low volatile organic compound (VOC) of <2, or <1, ​​or <0.8, or <0.5, or <0.2 wt % based on the total weight of the POP.

[0045] POP can have unimodal, broad unimodal, bimodal or multimodal profile in the gel permeation chromatography (GPC) curve generated according to the method of ASTM D6474-99. The term "unimodal" refers to the absence of more than one distinguishable peak in the GPC curve, and includes a peak in the GPC curve, wherein there is a peak. When there are local extreme values ​​between peaks, the bimodal GPC trace includes a curve, and the peak can be separated or deconvoluted. Alternatively, the term "bimodal" means that there are two maxima (which may be equal or may have a local and a global maximum) in the molecular weight distribution curve generated according to the method of ASTM D6474-99. The term "multimodal" means that there are two or more maxima (again, these maxima may have a single global maximum, but there may be more than one equal peak) in the molecular weight distribution curve generated according to the method of ASTM D6474-99.

[0046] In some embodiments, the POP is prepared in a metallocene-catalyzed polymerization process, such as a gas phase polymerization process. The terms "metallocene-catalyzed POP," "metallocene-produced POP," or "m-POP" as used herein refer to a POP having the density and MFI properties described herein and produced in the presence of a metallocene catalyst. A metallocene-catalyzed POP has measurable properties that are different from a POP having the same comonomers in the same weight percentage but produced by a different process, such as a conventional Ziegler-Natta polymerization process.

[0047] In some embodiments, POP is prepared using a gas phase metallocene catalyzed polymerization process. Gas phase polymerization refers to the polymerization of monomers in a fluidized bed. POP can be formed by polymerizing alpha-olefins under reaction conditions in a gas phase reactor having a fluidized bed and a fluidizing medium in the presence of a metallocene catalyst. In some embodiments, POP is obtained by polymerization in a single reactor. A variety of gas phase polymerization processes can be used, for example, polymerization can be carried out in non-condensing or "dry" mode, condensing mode or "super condensing mode".

[0048] In the gas phase polymerization process, the reactor temperature may be in the range of 30-140°C, or 60-120°C, 65-110°C, or 70-105°C, and the pressure is 100-1000, or 150-600, or 200-500, or 250-400 psig.

[0049] A metallocene catalyst may be a compound having a Group 4, 5 or 6 transition metal (M) and one or more cyclopentadienyl (Cp) ligands which may be substituted, at least one non-cyclopentadienyl derived ligand (X) and zero or one heteroatom containing ligand (Y) coordinated to M in an amount corresponding to its valence state. Metallocene catalysts / precursors generally require activation with a suitable cocatalyst (referred to as an "activator") to produce an "active metallocene catalyst", i.e., an organometallic complex with vacant coordination sites which can coordinate, insert and polymerize olefins.

[0050] In some embodiments, the POPs obtained from a gas phase polymerization process using a metallocene catalyst are characterized by a narrow composition distribution, which relates to the uniformity of the distribution of the comonomer in the polymer molecules. Metallocene catalysts are known to incorporate comonomers very uniformly in the polymer molecules they produce. POPs produced by metallocene catalyst systems can have a very narrow composition distribution because most polymer molecules will have approximately the same comonomer content, and within each molecule the comonomer will be randomly distributed.

[0051] Block copolymers

[0052] The block copolymer is at least one selected from the group consisting of a first HSBC, a second HSBC, MABC and a mixture thereof.

[0053] Each of the first HSBC and the second HSBC is independently obtained by hydrogenating an SBC precursor, which is any one of a linear, branched or radial block copolymer having at least one block A or A' and at least one block B or B'.

[0054] In some embodiments, the SBC precursor is prepared by anionic polymerization using techniques known in the art. Other methods, such as cationic polymerization, may also be used. Anionic polymerization initiators are typically organometallic compounds, such as organolithium compounds, such as ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, hexylbiphenyllithium, hexamethylenediyllithium, butadienyllithium, isoprenelithium, 1,1-diphenylhexyllithium or polystyrene lithium. The amount of initiator required is calculated based on the molecular weight to be achieved, typically 0.002-5wt%, based on the amount of monomer to be polymerized. Suitable solvents for polymerization include aliphatic, cycloaliphatic or aromatic hydrocarbons having 4-12 carbon atoms, such as pentane, hexane, heptane, cyclopentane, cyclohexane, methylcyclohexane, decalin, isooctane, benzene, alkylbenzenes (such as toluene, xylene or ethylbenzene), and mixtures thereof. Polymer chain termination can be achieved by quenching with a proton donor or a compound having a leaving group that can be displaced by the carbanionic polymer chain.

[0055] In some embodiments, the general configuration of the SBC precursor is: AB,ABA,BAB,ABAB,ABABA,(AB) n ,(AB) n (A),(ABA) n ,(ABA) n X,(AB) n X,(BAB) n X,(ABAB) n X,(ABABA) n X,A'-B',A'-B'-A',B'-A'-B',A'-B'-A'-B',A'-B'-A'-B'-A',(A'-B') n ,(A'-B') n (A'),(A'-B'-A') n ,(A'-B'-A') n X,(A'-B') n X,(B'-A'-B') n X,(A'-B'-A'-B') n X,(A'-B'-A'-B'-A') n X, or a mixture thereof; wherein n is an integer of 2-30, and X is a residue of a coupling agent. Each block A and A' is identical or different and independently derived from a vinyl aromatic monomer, and each block B and B' is identical or different and independently derived from a conjugated diene monomer.

[0056] In some embodiments, the coupling agent includes a difunctional or polyfunctional compound, such as divinylbenzene, aliphatic or aromatic aliphatic hydrocarbon halides (e.g., 1,2-dibromoethane, bis(chloromethyl)benzene, silicon tetrachloride, dialkyl or diaryl silicon dichloride, alkyl or aryl silicon trichloride, tin tetrachloride), alkyl silicon methoxide, alkyl silicon ethoxide, polyfunctional aldehydes (e.g., terephthalaldehyde), ketones, esters, anhydrides or epoxides. In some embodiments, the coupling agent is selected from methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), tetramethoxysilane (TMOS), dimethyl adipate, γ-glycidoxypropyltrimethoxysilane, and mixtures thereof.

[0057] In some embodiments, the vinyl aromatic monomer is selected from styrene, p-methylstyrene, p-ethylstyrene, p-n-propylstyrene, p-isopropylstyrene, p-n-butylstyrene, p-sec-butylstyrene, p-isobutylstyrene, p-tert-butylstyrene, isomers of p-decylstyrene, isomers of p-dodecylstyrene, ortho-substituted styrenes, meta-substituted styrenes, α-methylstyrene, 1,1-diphenylethylene, and mixtures thereof.

[0058] In some embodiments, the conjugated diene monomer is selected from the group consisting of isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1-phenyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 3-butyl-1,3-octadiene, farnesene, myrcene, piperidine, cyclohexadiene, and mixtures thereof.

[0059] In some embodiments, each block A and A' independently has a molecular weight (Mp) of 1-40, or 1-35, or 1-30, or 1-25, or 1-20, or 1-10, or >1, or >2, or <40, or <35, or <25 kg / mol.

[0060] In some embodiments, block B prior to hydrogenation has a vinyl content of 0-60, or 0-50, or 0-45, or <60, or <50, or <45 wt % based on the total weight of polymerized conjugated diene monomers in block B.

[0061] In some embodiments, block B' has a vinyl content of 60-90, or 65-85, or 70-85, or 75-85, or >60, or >65, or >70 wt % prior to hydrogenation, based on the total weight of polymerized conjugated diene monomers in block B'.

[0062] In some embodiments, each block B and B' independently has a molecular weight (Mp) of 10-300, or 20-200, or 50-200, or 20-150 kg / mol.

[0063] In some embodiments, the polystyrene content (PSC) of the first HSBC is 3-20, or 5-18, or 4-15, or >3, or <20 wt %, based on the total weight of the first HSBC.

[0064] In some embodiments, the second HSBC has a polystyrene content (PSC) of 15-30, or 17-28, or 15-25, or >10, or >15, or <30 wt %, based on the total weight of the second HSBC.

[0065] In some embodiments, each of the first HSBC and the second HSBC independently has a molecular weight (Mp) of 40-800, or 50-780, or 60-760, or 40-250, or 50-200, or 650-800 kg / mol.

[0066] In some embodiments, the first HSBC has a melt flow rate (MFR) of 5-40, or 10-35, or 15-30, or 15-40, or 5-30, or >10, or >15 dg / min, measured according to ASTM D 1238 at 230°C and 5 kg load.

[0067] In some embodiments, the second HSBC has a melt flow rate (MFR) of 5-40, or 10-35, or 15-30, or 15-40, or 5-30, or >10, or >15 dg / min as measured according to ASTM D 1238 at 230°C and 2.16 kg load.

[0068] In some embodiments, each of the first HSBC and the second HSBC independently has a coupling efficiency (CE) of >60%, or >65%, or >70%, or 60-98%, or 70-97%.

[0069] In some embodiments, each of the first HSBC and the second HSBC independently has a diblock content of <35, or <30, or 1-35, or 3-30 wt %, based on the total weight of the first HSBC and the second HSBC.

[0070] In some embodiments, each of the first HSBC and the second HSBC independently has a g / cm 3 density.

[0071] Each block A and A' derived from polymerized vinyl aromatic monomers may be substantially unhydrogenated. In some embodiments, each block A and A' independently has a hydrogenation level of <30, or <20, or <10, or <5%, based on the total double bonds present in each block A and A'. In some embodiments, each block B and B' is independently hydrogenated to a hydrogenation level of >80, or >85, or >90, or >95, or >98, or >99 or up to 100%, based on the total double bonds present in each block B and B'. The hydrogenation level refers to the percentage of the original unsaturated bonds that become saturated after hydrogenation, which can be measured using UV-VIS spectrophotometry and / or proton NMR and / or by ozonolysis titration.

[0072] In some embodiments, each of the first HSBC and the second HSBC is independently functionalized with at least one functional group (eg, hydroxyl, amino, carboxyl, anhydride, epoxy, isocyanate, silanol, etc.).

[0073] Multi-arm block copolymer (MABC)

[0074] In some embodiments, the block copolymer is a MABC selected from the group consisting of coupled hydrogenated polyisoprene arms of Formula I: (EP)nX, coupled hydrogenated polybutadiene arms of Formula II: (EB)nX, and mixtures thereof, wherein EP represents a polyisoprene unit and EB represents a polybutadiene unit. In each of (EP)nX and (EB)nX, X is the residue of a coupling agent and n is 3 to 10. The MABC is characterized in that it has no polymerized vinyl aromatic monomers.

[0075] MABC can be prepared by sequential (or continuous) polymerization of isoprene (for (EP)nX structures) or butadiene (for (EB)nX structures) monomers in solution in the presence of an initiator / catalyst, wherein the monomers and initiator are added stepwise, followed by coupling the resulting polymer with a coupling agent, and finally a hydrogenation step.

[0076] In some embodiments, the MABC is prepared by sequential living anionic polymerization in the presence of an initiator / catalyst, followed by coupling the resulting polymer with a coupling agent, and finally a hydrogenation step.

[0077] The process conditions of sequential polymerization can be similar to those used for anionic polymerization, for example, at a temperature of -30°C to 180°C, or 10-150°C or 30-120°C. The polymerization reaction is carried out in an inert atmosphere (e.g., nitrogen) or at a pressure of about 0.5-65 bar for <12 hours, or 5 minutes to 5 hours, depending on factors including temperature, monomer concentration, molecular weight of each block, etc. The polymerization reaction is carried out in the presence of a suitable amount of solvent (e.g., ether, benzene, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane, etc.). After polymer formation and after coupling reaction, the polymerization mixture is optionally treated with a proton donor terminator (e.g., water, carbon dioxide, hydrogen, alcohol, phenol or linear saturated aliphatic monocarboxylic acid or dicarboxylic acid) to react with the polymer initiator before hydrogenation. The coupling agent can be used as described above. In some embodiments, after sequential polymerization, hydrogenation is carried out as described above.

[0078] In some embodiments, the MABC is a block copolymer containing coupled hydrogenated polyisoprene arms of the general formula I: (EP)nX, wherein X is the residue of a coupling agent, and n is 3-10.

[0079] In some embodiments, the MABC has an MFR of 3-30, or 5-20, or 7-15 g / 10 min, measured according to ASTM D1238 at 200°C and 5 kg load.

[0080] In some embodiments, the MABC has a CE of >90%, or >92%, or >94%, or 90-99%, or 92-98%.

[0081] In some embodiments, the MABC has a residual unsaturation (RU) of 0.01-1, or 0.02-0.8, or 0.04-0.5, or 0.01-0.1 meq / g.

[0082] In some embodiments, the MABC has a molecular weight (Mp) of 300-700, or 350-650, or 400-650, or 420-600 kg / mol.

[0083] Impact Modifier Composition (IMC)

[0084] The IMC comprises: (a) 50-97 wt% POP, and (b) 3-50 wt% of at least one block copolymer as described above; or (a) 70-95 wt% POP and (b) 5-30 wt% of at least one block copolymer, based on the total weight of the composition.

[0085] In some embodiments, the IMC comprises a POP and the at least one block copolymer in a weight ratio of 19:1-1:1, or 18:2-1:1, or 19:1-10:1, or 18:2-15:1.

[0086] Polyolefin composition

[0087] In some embodiments, the IMC is used in the polyolefin composition in an amount of 5-35, or 7-22, or 5-25, or 10-25, or 10-22 wt % based on the total weight of the polyolefin composition.

[0088] In some embodiments, the polyolefin composition comprises: (A) 50-90 wt% polyolefin, (B) 5-35 wt% IMC, and (C) 5-35 wt% at least one additive; or (A) 55-85 wt% polyolefin, (B) 5-25 wt% IMC, and (C) 10-25 wt% at least one additive, based on the total weight of the polyolefin composition.

[0089] Polyolefins

[0090] In some embodiments, the polyolefin is a polypropylene produced by any process known in the art. The polypropylene may be obtained from virgin or recycled sources, and when first produced may be petroleum-based or bio-based.

[0091] In some embodiments, polypropylene blends are used in polyolefin compositions, for example, the blend of random ethylene or butene copolymer of polypropylene or the combination of crystalline random copolymer of ethylene and propylene and rubbery ethylene-propylene copolymer.Polypropylene copolymers can be used, including copolymers of propylene and copolymerizable comonomers (for example ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene) or one or more conjugated or non-conjugated dienes.Gross weight based on polypropylene copolymer, comonomer can be in the scope of 0.05-40 or 0.5-30 or 1-20 or 5-30wt%.

[0092] In some embodiments, the polypropylene is a heterophasic polymer composition comprising a propylene homopolymer matrix, or a random copolymer matrix in which a propylene copolymer component and one or more ethylene or higher alpha-olefin comonomers are dispersed. The random copolymer matrix includes propylene monomers and at least one comonomer selected from the group consisting of ethylene, C4-C8 alpha-olefins (e.g., 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene), and mixtures thereof.

[0093] From the perspective of molecular weight, polypropylene can be bimodal or multimodal. In some embodiments, the number average molecular weight (Mn) of polypropylene is 10-200, or 30-150, or 50-100, or 30-120, or 40-140 kg / mol. In some embodiments, the weight average molecular weight (Mw) of polypropylene is 50-2000, or 150-1500, or 200-1000, or 100-800, or 150-800, or 100-400 kg / mol.

[0094] In some embodiments, the polypropylene has a melting temperature (Tm) of 100-180°C, or 110-170°C, or 120-160°C, or 125-150°C, as measured by DSC according to ASTM D3418.

[0095] In some embodiments, the polypropylene has a crystallinity of 20-70%, or 25-65%, or 30-60%, or 35-55%, or >35%, or >40%, or >50%, as measured by DSC heat of fusion according to ASTM D3418.

[0096] In some embodiments, the polypropylene has a melt flow index (MFI) of 5-100, or 10-50, or 5-45, or 10-40 g / 10 min, measured according to ASTM D1238 at 230° C. and 2.16 kg load.

[0097] In some embodiments, the density of the polypropylene is 0.870-0.910, or 0.875-0.905, or 0.895-0.905 g / cm 3 .

[0098] In some embodiments, the amount of polypropylene used in the polyolefin composition is 50-90, or 55-85, or 60-75, or 50-70, or 60-80 wt %, based on the total weight of the polyolefin composition.

[0099] additive

[0100] The polyolefin composition comprises an additive selected from the group consisting of activators, curing agents, stabilizers, neutralizers, thickeners, coalescing agents, slip agents, mold release agents, biocides, surfactants, antioxidants, antiozonants, color-changing pH indicators, plasticizers, tackifiers, film-forming additives, dyes, pigments, UV stabilizers, UV absorbers, catalysts, fillers, other resins, fibers, flame retardants, viscosity modifiers, wetting agents, deoxidizers, toughening agents, tackifiers, colorants, heat stabilizers, light stabilizers, lubricants, flow modifiers, drip agents, anti-blocking agents, antistatic agents, processing aids, stress relief additives, foaming agents, weld strength promoters, and mixtures thereof.

[0101] Examples of fillers include sand, talc, dolomite, calcium carbonate, clay, silica, mica, wollastonite, feldspar, aluminum silicate, aluminum oxide, hydrated aluminum oxide, glass beads, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, wood flour, glass fiber, wood fiber, carbon fiber, and mixtures thereof. The filler may be surface treated before being added to the polyolefin composition.

[0102] In some embodiments, the additive used in the polyolefin composition ranges from 5-35, or 5-30, or 10-25, or 10-20, or 5-20 wt % based on the total weight of the polyolefin composition.

[0103] In some embodiments, the polyolefin composition further comprises an impact modifier in addition to the above-mentioned IMC. The examples of other impact modifiers include ethylene-propylene-diene-diene (EPDM) monomers, ethylene-propylene (EPM) monomers, ethylene-propylene rubber (EPR), elastomeric polyolefins (POE), based on binary copolymers and terpolymers of ethylene and propylene, acrylonitrile-butadiene rubber (NBR), isobutylene (IB), chlorinated rubber, chlorinated polyethylene (CM), isoprene, ethylene-butylene, and mixtures and derivatives thereof. Based on the gross weight of the polyolefin composition, 0-25, or 1-20, or 5-20wt% of other impact modifiers can be used in the polyolefin composition.

[0104] Preparation method of IMC

[0105] IMCs may be prepared by using appropriate amounts of the components and dry blending followed by direct mixing with other components of the polyolefin composition, or dry blending and melt extruding into pellets and subsequent blending with other components using known methods and equipment.

[0106] Method for processing impact-modified polyolefin compositions / articles

[0107] The polyolefin composition can be processed according to methods known in the art, wherein the components are combined and blended by melt mixing / extrusion into pellets and subsequently formed into articles by known techniques such as injection molding, overmolding, rotational molding, thermoforming, casting, extrusion, profile extrusion and blow molding.

[0108] The polyolefin composition may be compounded by equipment including a continuous single screw or twin screw mixer. In some embodiments, the polyolefin composition is prepared by a dry blending process to obtain a dry blended polyolefin composition.

[0109] In some embodiments, the compounding temperature of each component of the polyolefin composition will vary with the polyolefin composition, for example 100-300 ℃, or 150-280 ℃, or 180-260 ℃, or 200-270 ℃. The various components of the final polyolefin composition can be added and compounded with each other in any order or simultaneously. In some embodiments, additives are added in the form of premixed masterbatch. This masterbatch is typically formed by dispersing additives. Masterbatch can be easily formed by melt compounding method.

[0110] Properties of impact-modified polyolefin compositions

[0111] The polyolefin compositions modified by IMC are characterized by having balanced flexibility, impact, stiffness, tensile strength, flow and anisotropy when formed into articles.

[0112] In some embodiments, the polyolefin composition has an impact strength of 24-50, or 25-45, or 25-40, or >24 kJ / m measured at 23°C according to ISO 179. 2 In some embodiments, the impact strength of the polyolefin composition is 20-70, or 22-65, or 25-60, or >22 kJ / m measured at 23°C according to ASTM D256. 2 .

[0113] In some embodiments, the impact strength of the polyolefin composition is 3.2-12, or 3.3-10, or 3.4-8, or >3.2 kJ / m measured at -30°C according to ISO 179. 2In some embodiments, the impact strength of the polyolefin composition is 3.4-20, or 3.5-18, or 3.5-15, or >3.4 kJ / m measured at -30°C according to ASTM D256. 2 .

[0114] In some embodiments, the polyolefin composition has a flexural modulus of 900-1400, or 930-1350, or 950-1300, or >900, or <1350 MPa, as measured according to ASTM D790.

[0115] In some embodiments, the shrinkage of the polyolefin composition is <10, or <9, or <8, or 3-10, or 3.5-8 mils / inch (or 1 / 1000). "Mil per inch" (mil / inch) is a unit of measurement used to describe the thickness (or size) of a coating or material, or the shrinkage of a film or thickness over a given length, i.e., a few thousandths per inch of thickness or a shrinkage per inch of length. "Mil" is one thousandth of an inch (0.001 inch or 0.0254 mm). In terms of shrinkage, for example, if a plastic film shrinks 2 mils per inch, it means that the film will shrink 0.002 inches per inch of length. When converted to the metric system, the value in μm / mm = the value in mil / foot × 25.4. For example, if the shrinkage is 5 mils / inch, the metric equivalent is: (5 mils / inch) × 25.4 = 127 μm / mm.

[0116] In some embodiments, the polyolefin composition has a flexural strength of 20-40, or 22-35, or 20-30 MPa, measured according to ASTM D790.

[0117] In some embodiments, the polyolefin composition has a crystallization temperature (Tc) of 120-140°C, or 122-135°C, or 125-134°C, or 124-132°C.

[0118] In some embodiments, the polyolefin composition has at least one of the following balanced properties compared to a polyolefin composition in the absence of the IMC:

[0119] (i) an increase of >3% in impact strength measured at 23°C, and (ii) a decrease of <2% in impact strength measured at -23°C; or

[0120] (iii) an increase in impact strength measured at 23°C of >3%, and (iv) an increase in impact strength measured at -23°C of >2%; or

[0121] (v) an increase in flexural modulus measured at 23°C of >2%, and (vi) an increase in impact strength measured at 23°C of >3%; or

[0122] (vii) an increase in flexural modulus measured at 23°C by >2%, and (viii) an increase in impact strength measured at -23°C by >2%.

[0123] Application of impact-modified polyolefin compositions

[0124] The impact modified polyolefin composition can be used to prepare various articles by injection blow molding, injection molding, extrusion blow molding, coextrusion molding, cast film extrusion, blown film extrusion, injection stretch blow molding, rotational molding, thermoforming, hot melt, foam blowing, pultrusion, calendering, additive manufacturing or other known processing methods.

[0125] Hollow articles can be obtained from the polyolefin composition by continuous extrusion blow molding or intermittent extrusion blow molding. In some embodiments, the hollow articles include bottles, containers, fuel tanks, drums, etc. Other molded articles include furniture, signs, wheels, toys, gardening products, etc.

[0126] The polyolefin composition can be used in pipes, packaging applications, films, geomembranes, roofing applications, pond liners, covers and closures, and core layers of multilayer polyolefin sheets or films, container household goods, medical moldings, bottles and caps. The polyolefin composition can be used in automotive applications such as interior trim, inner jackets, door panels, dashboards, panels, lift gates, consoles, etc.

[0127] In some embodiments, the polyolefin composition is used to prepare textile fibers, which are then used to form spunbond fibers, staple fibers, multi-fiber yarns, knitted fabrics, woven fabrics, or nonwoven fabrics. Example

[0128] The following examples are non-limiting.

[0129] The following test method was used.

[0130] Shrinkage: The shrinkage of plastic materials occurs as the molded part cools after injection molding. The shrinkage of the plastic material (specimen) can be expressed as thousandths of an inch per linear inch (0.00X / inch / inch) and calculated as:

[0131] Shrinkage = (cavity size - sample size) / (cavity size) (II)

[0132] Crystallization temperature (Tc): Tc was measured using differential scanning calorimetry (DSC) in cooling mode. The sample was cooled from 200°C to -90°C at a rate of 10°C / min after initial heating. The temperature corresponding to the peak in the DSC curve is denoted as (Tc).

[0133] The components used in the examples include:

[0134] POP-1 is an ethylene-butene copolymer with an MFI of 5 g / 10 min at 190 °C and 2.16 kg load, an MFI of 85 g / 10 min at 190 °C and 21.6 kg load, a melt index ratio of 17, and a density of 0.900 g / cm 3 and has 0.9LCB / 10 6 A carbon.

[0135] POP-2 is an ethylene-butene copolymer with an MFI of 5 g / 10 min at 190 °C and 2.16 kg load, an MFI of 85 g / 10 min at 190 °C and 21.6 kg load, a melt index ratio of 17, and a density of 0.885 g / cm 3 and has 1.3LCB / 10 6 A carbon.

[0136] POP-3 is an ethylene-hexene copolymer with an MFI of 5 g / 10 min at 190 °C and 2.16 kg load, an MFI of 90 g / 10 min at 190 °C and 21.6 kg load, a melt index ratio of 18, and a density of 0.900 g / cm 3 and has 1.1LCB / 10 6 A carbon.

[0137] POP-4 is an ethylene-hexene copolymer with an MFI of 5 g / 10 min at 190 °C and 2.16 kg load, an MFI of 90 g / 10 min at 190 °C and 21.6 kg load, a melt index ratio of 18, and a density of 0.885 g / cm 3 and has 1.5LCB / 10 6 A carbon.

[0138] The first HSBC-1 is a poly(styrene-ethylene / butylene-styrene) (SE / BS) copolymer having an MFR of 22 g / 10 min at 230°C and a load of 5 kg and a density of 0.890 g / cm 3 , PSC is 13wt%, vinyl content is 44wt%, CE is 71%, the molecular weight (Mp) of the polystyrene block is 5.3kg / mol, the total molecular weight (Mp) of the first HSBC-1 is 145kg / mol, and the diblock content is 29wt%.

[0139] The first HSBC-2 is a poly(styrene-ethylene / propylene) (S-EP) block copolymer having a density of 0.900 g / cm 3, PSC is about 5.5wt%, CE is 95%, the molecular weight (Mp) of the polystyrene block is 3.5kg / mol, the total molecular weight (Mp) of the first HSBC-2 is 750kg / mol, and the diblock content is 5wt%.

[0140] The first HSBC-3 is a poly(styrene-ethylene / propylene-ethylene / butylene) (S-EP / EB) block copolymer having a density of 0.900 g / cm 3 , PSC is 7wt%, CE is 95%, the molecular weight (Mp) of the polystyrene block is 2.9kg / mol, and the total molecular weight (Mp) of the first HSBC-3 is 74.5kg / mol.

[0141] The second HSBC-1 is a poly(styrene-ethylene / butylene-styrene) (SE / BS) copolymer having an MFR of 19 g / 10 min at 230°C and a load of 2.16 kg and a density of 0.900 g / cm 3 , PSC is 18.6wt%, vinyl content is 79wt%, CE is 93%, the molecular weight (Mp) of the polystyrene block is 6.2kg / mol, the total molecular weight (Mp) of the second HSBC-1 is 123kg / mol, and the diblock content is 7wt%.

[0142] MABC-1 is a multi-arm block copolymer with coupled hydrogenated polyisoprene arms (EP) having an MFR of 8 g / 10 min at 200°C and 5 kg load and a density of 0.900 g / cm 3 , CE is 95%, the total molecular weight (Mp) of MABC-1 is 488 kg / mol, the diblock content is 5 wt%, and the RU is 0.05 meq / g.

[0143] PP-1 is polypropylene with an MFI of 32 g / 10 min at 230 °C and 2.16 kg load and a density of 0.900 g / cm 3 .

[0144] IMC-A is an ethylene-octene copolymer with an MFI of 5 g / 10 min at 190 °C and a load of 2.16 kg and a density of 0.868 g / cm 3 , melt index ratio of 30, and has a 2.1LCB / 10 6 A carbon.

[0145] IMC-B is an ethylene-butene copolymer with an MFI of 5 g / 10 min at 190 °C and a load of 2.16 kg and a density of 0.865 g / cm 3 , melt index ratio is 33, with 3.5LCB / 10 6 A carbon.

[0146] AO-1 is a phenolic antioxidant (tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane).

[0147] AO-2 is a phosphite antioxidant (tris(2,4-di-tert-butylphenyl) phosphite).

[0148] AO-3 is Irganox 1010 from BASF.

[0149] Example 1

[0150] An impact modifier composition was prepared.

[0151] As shown in Table 1, HSBC and POP were blended at 170°C in different amounts of each HSBC or MABC and POP by using a twin-screw extruder.

[0152] Table 1

[0153]

[0154] Example 2

[0155] A polyolefin composition is prepared.

[0156] A twin-screw extruder was used to blend appropriate amounts of the components of the polyolefin composition at 210°C to obtain a polyolefin composition in the form of pellets. Polyolefin composition samples were then prepared by injection molding at mold temperatures of 230°C and 40°C. These samples were used to measure various properties. The details of the polyolefin composition and the test results are shown in Tables 2 and 3, respectively.

[0157]

[0158]

[0159] The term "comprising / including" as used herein means including the elements or steps identified after the term, but any such elements or steps are not exhaustive, and embodiments may include other elements or steps. Although the terms "comprising" and "including" have been used herein to describe various aspects, the terms "consisting essentially of" and "consisting of" may replace "comprising" or "including" to provide more specific aspects of the present disclosure, and are also disclosed.

Claims

1. An impact modifier composition comprising: (a) 50-97 wt% of a polyolefin plastomer having the following properties: Density measured according to ASTM D1505 is 0.870-0.920 g / cm 3 , The melt flow index measured according to ASTM D1238 at 190°C and 2.16 kg load is 0.5-30 g / 10 min, Melt index ratio is 10-22, and Long chain branching is <15LCB / 10 6 carbon, and (b) 3 to 50 wt% of at least one block copolymer selected from: (i) a first hydrogenated styrenic block copolymer having blocks A and blocks B, wherein prior to hydrogenation, each block A is a polymer block of a vinyl aromatic monomer, and each block B is a polymer block of a conjugated diene monomer, and wherein the vinyl content of block B is 0 to 60 wt%, The polystyrene content of the first hydrogenated styrenic block copolymer is 3-20wt%; (ii) a second hydrogenated styrenic block copolymer having blocks A′ and blocks B′, wherein prior to hydrogenation, each block A′ is a polymer block of a vinyl aromatic monomer, and each block B′ is a polymer block of a conjugated diene monomer, and wherein the vinyl content of block B′ is from 60 to 90 wt %, The second hydrogenated styrenic block copolymer has a polystyrene content of 15-30 wt %; and (iii) at least one multi-arm block copolymer selected from the group consisting of: (iiia) having the general formula I: (EP) n X is a coupled hydrogenated polyisoprene arm, and (iiib) has the general formula II: (EB) n X is a coupled hydrogenated polybutadiene arm, wherein X is the residue of a coupling agent, and n is 3-10.

2. The impact modifier composition of claim 1, wherein the polyolefin plastomer has a LCB / 10 6 Long chain branching (LCB) of one carbon.

3. The impact modifier composition of any one of claims 1-2, wherein the at least one block copolymer is a first hydrogenated styrenic block copolymer having the following properties: The molecular weight (Mp) of block A is 1-40 kg / mol, The vinyl content of block B is 0-50 wt%, The polystyrene content is 4-15 wt%, and The molecular weight (Mp) of the first hydrogenated styrenic block copolymer is 20-300 kg / mol.

4. The impact modifier composition of any one of claims 1-2, wherein the at least one block copolymer is a second hydrogenated styrenic block copolymer having the following properties: The molecular weight (Mp) of block A' is 1-40 kg / mol, The vinyl content of block B' is 70-85 wt%, The polystyrene content is 15-25 wt%, and The molecular weight (Mp) of the second hydrogenated styrenic block copolymer is 20-300 kg / mol.

5. The impact modifier composition of any one of claims 1-2, wherein the weight ratio of the polyolefin plastomer to the at least one block copolymer is from 19:1 to 10:

1.

6. The impact modifier composition of any one of claims 1-2, wherein the at least one block copolymer is a multi-arm block copolymer having the following properties: The melt flow rate measured at 200°C and 5 kg load according to ASTM D1238 is 3-30, The coupling efficiency is >90%, The residual unsaturation is 0.01-1 meq / g, and The molecular weight (Mp) is 300-700 kg / mol.

7. The impact modifier composition according to any one of claims 1-2, wherein the polyolefin plastomer has at least one of the following properties: Density: 0.880-0.910g / cm 3 , The melt flow index is 0.5-20g / 10min, and The melt index ratio is 12-20.

8. The impact modifier composition according to any one of claims 1 to 2, wherein the polyolefin plastomer is composed of ethylene and one or more C 3-20 Ethylene copolymers obtained with α-olefin comonomers.

9. The impact modifier composition according to any one of claims 1-2, wherein the polyolefin plastomer is at least one selected from ethylene-butene copolymer, ethylene-hexene copolymer, and a mixture thereof.

10. A polyolefin composition comprising: (A) 50-90 wt% of polyolefin, (B) 5-35 wt% of the impact modifier composition of any one of claims 1-9, and (C) 5-35 wt% of at least one additive, Based on the total weight of the polyolefin composition.

11. The polyolefin composition of claim 10, wherein the polyolefin composition has at least one of the following properties when compared to a polyolefin composition in the absence of the impact modifier composition: (i) an increase of >3% in impact strength measured at 23°C, and (ii) a decrease of <2% in impact strength measured at -23°C; or (iii) an increase in impact strength measured at 23°C of >3%, and (iv) an increase in impact strength measured at -23°C of >2%; or (v) an increase in flexural modulus measured at 23°C of >2%, and (vi) an increase in impact strength measured at 23°C of >3%; or (vii) an increase in flexural modulus measured at 23°C by >2%, and (viii) an increase in impact strength measured at -23°C by >2%, Among them, the impact strength is measured according to ISO 179, and the flexural modulus is measured according to ASTM D790.

12. The polyolefin composition according to any one of claims 10-11, wherein the polyolefin is polypropylene.

13. The polyolefin composition of claim 12, wherein the polypropylene has at least one of the following properties: A melt flow index of 5-100 g / 10 min measured at 230° C. and 2.16 kg load according to ASTM D1238, and Density measured according to ASTM D1505 is 0.870-0.910 g / cm 3 .

14. The polyolefin composition according to any one of claims 10-11, wherein the polyolefin composition has at least one of the following properties: Impact strength measured at 23°C according to ISO 179 is 24-50 kJ / m 2 , Impact strength measured at -30°C according to ISO 179 is 3.2-12 kJ / m2, Flexural modulus of 900-1400 MPa measured according to ASTM D790, and The flexural strength measured according to ASTM D790 is 20-40 MPa.

15. The polyolefin composition of any one of claims 10-11, wherein the polyolefin composition has a shrinkage of less than 10 mils / inch.

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