Thermoplastic polymer composition with reduced migration of stabilizers

Abstract

A thermoplastic polymer composition (A) which leads to a reduction in the migration of stabilizers or other ingredients (I) which is based on a polymer composition (A) containing 50 to 90 % by weight of a thermoplastic plastic (P) having migration barrier properties and at least one stabilizer component (S) and / or other components (I), wherein for the polymer composition (A): a) the glass transition temperature T of the thermoplastic polymer (P) is greater than the use temperature; b) the polymer-specific constant (A p ) of the polymer of the thermoplastic polymer (P) is less than 1; c) the mineral oil diffusion coefficient (D p ) of the thermoplastic polymer (P) is less than 10 ‑12 cm 2 / s at 20 °C; d) the morphology of the thermoplastic polymer (P) is either a single-phase homogeneous or a two-phase heterogeneous phase.

Description

[0001] This invention relates to thermoplastic polymer compositions in which the migration of stabilizers and / or other components is reduced. These thermoplastic polymer compositions comprise at least one thermoplastic polymer having properties that block the migration of stabilizers and / or other components, and in one embodiment, further comprise at least one stabilizer component.

[0002] To date, the functional barrier properties of various polymers and multilayer composite structures have not been adequately studied in practice (see, for example, Rainer Brandsch’s paper “Recycled cardboard and paper for food packaging? Introducing functional barrier properties can minimize the migration of mineral oil from cardboard packaging to food” (InnoLETTER, pp. 1-8, June 7, 2010, www.innoform.de).

[0003] The role of polymers, polymer blends, and composite structures as functional barriers (FBs) is primarily related to the transportability of gases such as oxygen, carbon dioxide, nitrogen, and / or water vapor. In this context, the functional barrier properties of polymers and multilayer composite structures relative to compounds (e.g., organic molecules) are described in the scientific literature in the form of specific physical and thermodynamic compound constants. This allows for the selection of materials to protect contents (such as food) within packaging from contamination by potentially toxicological or olfactory-related compounds.

[0004] For example, in the long-term use of packaging systems, risk assessments can be developed based on the functional barrier properties of the materials, and action plans can be derived from them. This can ensure the safe use of packaging materials, including printing inks, varnishes, coatings, and adhesives, for food or pharmaceutical products. Therefore, in general, there is no need to conduct time-consuming and expensive laboratory tests, or such tests are minimized.

[0005] Therefore, one object of the present invention is to provide a thermoplastic polymer composition that can be produced inexpensively, characterized by reduced migration of its constituent components and / or stabilizers. The thermoplastic polymer composition can be used to produce composite systems having two or more layers.

[0006] The following describes a thermoplastic polymer composition (A) with reduced migration comprising at least 20% by weight, more particularly at least 50% by weight, and typically at least 80% by weight of at least one thermoplastic polymer (P) based on the polymer composition (A), which exhibits migration-blocking properties, particularly for stabilizers.

[0007] The polymer composition (A) typically contains at least 0.1% by weight, more particularly 0.1-2.0% by weight, of at least one stabilizer component (S). It typically also includes other ingredients and / or additives.

[0008] More specifically, the present invention relates to a thermoplastic polymer composition (A) for reducing the migration of stabilizer (S) and / or other components (I), comprising at least 20% by weight, more particularly at least 50% by weight, and typically at least 80% by weight of at least one thermoplastic polymer (P), and optionally at least 0.1% by weight, typically 0.1–2.0% by weight of at least one stabilizer component (S) based on the polymer composition (A) and / or at least 0.1% by weight of / or at least one additional component (I) based on the polymer composition (A), wherein in the thermoplastic polymer component (A):

[0009] a) The glass transition temperature (Tg) of the thermoplastic polymer (P) is higher than the service temperature.

[0010] b) The polymer-specific constant (A) of thermoplastic polymers (P). P ) less than 1, and

[0011] c) The mineral oil diffusion coefficient (D) of the thermoplastic polymer (P) at 20°C. P Less than 10 -12 cm 2 / s, and

[0012] d) Thermoplastic polymers (P) exist in the form of a single-phase homogeneous phase or a two-phase heterogeneous phase.

[0013] Among them, when the thermoplastic polymer (P) is in a two-phase heterogeneous state, it has a higher A P and a higher diffusion coefficient (D P The polymer component (Pp) exists as a discontinuous phase in the form of particles with a weight-average particle size (D) of 20 nm to 10 μm, which are embedded in a lower A P and a lower diffusion coefficient (D P In the polymer component (Pm), and

[0014] Thermoplastic polymers (P) do not have a co-continuous structure.

[0015] Migration barrier properties refer to the prevention or at least delay of the migration of stabilizers and / or other components in a polymer composition. Heterogeneous morphology refers to the absence of a homogeneous structure in a polymer or polymer mixture. This can be assessed, for example, through microscopic examination.

[0016] One embodiment of the present invention relates to a thermoplastic polymer composition (A) having reduced migration, comprising at least one thermoplastic (P) in 50 to 99.9% by weight based on the polymer composition (A), and at least 0.1% by weight, typically 0.1 to 2.0% by weight based on the polymer composition (A), and at least 0.1% by weight, typically 0.1 to 2.0% by weight based on the polymer composition (A), and at least 0.1% by weight, typically 0.1 to 2.0% by weight based on the polymer composition (A), and at least 0.1% by weight, typically 0.1 to 2.0% by weight, of the polymer composition (A).

[0017] One embodiment of the present invention relates to a thermoplastic polymer composition (A) having reduced migration, comprising a styrene-containing polymer as a thermoplastic polymer (P) having a glass transition temperature Tg of at least 60°C, more particularly at least 70°C.

[0018] The thermoplastic polymer composition (A) with reduced migration, particularly for stabilizers, preferably includes a styrene-containing polymer component as a thermoplastic polymer (P), more particularly selected from polystyrene (PS), and more particularly HIPS and GPPS, as well as SBS copolymers / PS blends.

[0019] Preferably, an SBC copolymer / PS blend is used in the composition.

[0020] Another embodiment of the invention relates to a thermoplastic polymer composition (A) having reduced migration, comprising at least one stabilizer component (S) from an antioxidant and a light stabilizer and / or at least another component (I) from residual monomers and oligomers. The various stabilizer components (S) and other components (I) will be described in detail below.

[0021] Another embodiment of the invention relates to a migration-reducing thermoplastic polymer composition (A) comprising at least one stabilizer component (S), typically 0.1 to 2.0% by weight, and more particularly at least one antioxidant, based on the polymer composition (A). This will be described below.

[0022] Another subject of the invention is a composite structure, more particularly suitable for packaging applications, comprising at least two distinct layers (S).

[0023] At least one layer (S1) here consists of or is mainly composed of a thermoplastic polymer composition (A) having the reduced migration properties described above.

[0024] The composite structure for packaging typically comprises at least two distinct layers, wherein at least one layer (S1) is primarily composed of a thermoplastic polymer composition (a), particularly polystyrene (PS), SBS copolymer / PS blends, and / or SBC copolymer / PS blends, and at least one additional layer (S2) primarily comprises a styrene-free thermoplastic polymer composition (A2). This additional thermoplastic polymer composition (A2) may be composed of, for example, polyester, polyurethane, and / or polyamide.

[0025] Another subject of the invention is a method for producing a thermoplastic polymer composition (A) as described above, having the effect of reducing the migration of stabilizer (S) and / or other components (I), wherein at least one thermoplastic polymer (P) having migration-blocking properties is mixed with at least one stabilizer component (S) and optionally other polymer additives. Other polymer additives will be described below.

[0026] The present invention further relates to the use of a thermoplastic polymer composition (A) with reduced migration of the stabilizer (S) and / or other components (I) as described above for the production of films, fibers or molded articles.

[0027] Another subject of the invention is the use of the composite structure comprising at least two different layers, wherein at least one layer (S1) consists of a migration-reducing thermoplastic polymer composition (A) for providing packaging with enhanced anti-delamination properties. Delamination here refers to layer separation in the composite structure. This is a technical challenge, particularly when two or more layers are present, for example, layers (S1), (S2), and / or (S3) as described above.

[0028] In particular, the barrier properties of a polymer relative to organic molecules can be measured by the polymer specific constant (A). P The value of ) is used to describe it.

[0029] T. Begley and L. Castle et al. described this constant in “An Evaluation of Migration Models That May Be Used to Support Regulations on Plastics in Food Contact” (Food Additives and Contaminants, January 2005; Vol. 22(1): 73–90). Polymer Specific Constant A P The equation is as follows (Equation 1).

[0030] A P =A P '-τ / T (Equation 1)

[0031] The polymer specific constant (A) described in the article published in 2005 PThe value is determined by component A, which is independent of temperature. P It consists of the activation energy contribution (τ, Tau) related to temperature. T in Equation 1 represents temperature.

[0032] Table 1 describes the polymer specificity constants A for some commonly used polymers. P It can be used for purposes including the production of packaging materials.

[0033]

[0034] Polymer ratio constant A P It is a measure of the mobility of polymers at the molecular level, and therefore can be used to estimate their barrier properties (or diffusion properties).

[0035] Flexible polymers, such as polyethylene (LDPE) or plasticized polyvinyl chloride (PVC), typically have high fluidity, which means they have a correspondingly higher A value. P Value and diffusion coefficient D p This results in low barrier performance.

[0036] More rigid polymers, such as polyethylene terephthalate (PET) or polyamide (PA), typically have lower migration rates, which means they have correspondingly lower Am. P Value and diffusion coefficient D p Therefore, it has better barrier properties.

[0037] The diffusion coefficient (D) is described below using the diffusion equation. p ):

[0038] D P ~exp(A P -0.1351Mr 2 / 3 +0.003Mr-10454 / T) (Equation 2)

[0039] Polymer specificity constant A p The polymer matrix (e.g., free volume, chain mobility) is described and is temperature-dependent, as shown in Equation 1 above. Mr is the molecular weight of the migrating agent (e.g., stabilizer, additive); T is the temperature.

[0040] The solubility of migrating additives in polymers or polymer compositions further contributes to the polymer barrier effect. Solubility is compound-specific and has been described only to a limited extent in the literature, with the exception of a few media (such as water). If a compound has low solubility in a polymer, the polymer typically exhibits a higher barrier effect on that compound.

[0041] A typical example in this regard is that polyethylene (PE) has good barrier properties against water or water vapor because water is insoluble in PE. Due to its molecular size, migrating compounds also affect the barrier effect of polymers. Small molecules such as solvents, for example acetone, migrate faster in polymers than large molecules such as conventional polymer additives. An example in practical use is low-migration printing inks. For example, in order to ensure low migration values, large molecules such as polymer photoinitiators are deliberately used.

[0042] The thickness of the polymer product itself also affects its barrier effect. For example, a thick polymer layer used in a beaker or tray has a higher barrier effect than the same polymer film. The influence of temperature on the migration rate is high, which means that the migration rate of compounds is the same within a few hours under sterilization conditions (high temperature) and within a few years at room temperature (20 °C).

[0043] Whether the barrier effect (functional barrier) of a polymer in terms of specific applications (content, storage time, storage temperature) is sufficient can be evaluated by comprehensively considering all influencing variables (polymer type and polymer thickness, migrating compounds and their molecular weights and solubility in the polymer, storage time and storage temperature, nature of the content).

[0044] Mineral oil can be used to study barrier properties. For example, based on the barrier effect of a polymer against mineral oil (average molecular weight 300 - 520 g / mol) at room temperature (about 20 °C), a reasonable selection of packaging materials can be simply made from the polymer ratio constant (A P ). A high A P indicates a low barrier effect, and a low A P indicates a high barrier effect. Correspondingly, LDPE has little barrier effect against mineral oil. Even at a low thickness (about 10 μm), PET or polystyrene shows very good barrier effects.

[0045] Table 2 shows the polymer ratio constant (A P ) of polymers, as well as the diffusion coefficient (D P ) of mineral oil at room temperature (20 °C) derived therefrom:

[0046] <![CDATA[D P [cm 2 / s]]]> <![CDATA[A P ]]> gas ～10-1 liquid ～10-5 20 Viscous fluid ～10-6 18 Plasticized PVC ～10-7 16 Polymer T>Tg LDPE ～10-9 11 HDPE ～10-10 9 PP ～10-11 7 Polymer T <Tg PA ～10-13 2 PS ～10-14 Approximately 0 PET ～10-15 -2 Rigid PVC ～10-16 -4

[0047] Tg is the glass transition temperature; T < Tg means the use temperature is lower than the glass transition temperature of the polymer.

[0048] Based on A P , the molecular weight of the migrant, and temperature, the diffusion coefficient of mineral oil in the corresponding polymer can be estimated and used for migration simulation related to specific applications, that is, migration modeling based on the diffusion law.

[0049] However, real-world packaging systems typically consist of multiple materials and / or items, such as bottles and caps or thermoformed trays and cap films. Other items include labels, wrapping paper, sleeves, folding boxes, outer packaging, temporary packaging, etc., all or partly surrounding the contents (solid, liquid, paste). For example, some materials or items in a packaging system may come into direct contact with food or pharmaceuticals, while others may not. The transfer of mineral oils from recycled cardboard or paper primarily occurs via the gas phase. Gas-phase transfer is possible because mineral oils are sufficiently volatile to desorb from cardboard fibers and adsorb onto inner packaging and / or directly onto food.

[0050] The volatility of a compound can be expressed by its vapor pressure at a given temperature. It should be noted that the vapor pressure of a compound may differ significantly from the vapor pressure of the corresponding adsorbed or dissolved compound. Low molecular weight mineral oils are more volatile than high molecular weight mineral oils. The transfer of mineral oils into food is determined by two key parameters: first, the specific surface area of ​​the food, which allows for relatively non-specific adsorption of mineral oils; and second, the amount of freely available or readily accessible fat in the food, which is highly soluble in moderately polar to non-polar compounds, i.e., preferentially absorbed. For example, the high specific surface area of ​​foods such as flour, rice, and grains, and a fat content of several percentage points in foods (e.g., chocolate products or sandwiches), or the use of recycled cardboard or paper for packaging, indicate a high level of mineral oil migration.

[0051] Similar to functional barriers within materials or articles, the concept of functional barriers can be extended to composite structures. To this end, viewing a composite structure as concentric layers (S) that at least partially surround each other can aid in understanding.

[0052] The layer (S) surrounding the contents (e.g., inner bag) relative to other further outer layers (e.g., temporary packaging made of (recycled) cardboard) can vary depending on the functional barrier properties of the composite structure. The time (t) required for a compound (e.g., stabilizer component) to migrate from the outside (e.g., outer packaging) through the functional barrier (FB) layer (e.g., polymer composition) is also called the penetration time (θ) (see [reference needed]). Figure 3 ).

[0053] According to Equation 3 below, the penetration time (θ) is proportional to the thickness (d) of the layer (S), for example, proportional to the square of the thickness (dP) of the inner bag, and inversely proportional to the diffusion coefficient (DFB) of the material of the functional barrier (FB) (i.e., the material of the thermoplastic composition (A)).

[0054]

[0055] The mechanism of action of functional barriers (FB) is also Figure 1 and 2 The graph shows that if the polymer layer (S) does not have functional barrier properties, the observed migration time curve is as follows. Figure 1 As shown. If the migration of a compound (e.g., a stabilizer) is determined at two arbitrary time points, and if the two points are connected by a straight line, the line will intersect the y-axis describing the migration: the migration (mF, t / A) is always positive (I>0).

[0056] However, if the polymer layer (S) has functional barrier properties, the observed migration time distribution is as follows: Figure 2 As shown. If the migration of a compound (e.g., a stabilizer) is determined at two arbitrary time points, and these two points are connected by a straight line, the line will intersect the y-axis with a negative value (I<0) if one of the time points is within the permeation time (θ) (offset, mF, t / A).

[0057] When the penetration time (θ) is as long as possible, the functional barrier in the form of the polymer composition (A) is effective against the stabilizer component (or other components). In this case, the stabilizer component will not migrate or transfer from outside the functional barrier (FB) into, for example, the contents to be protected during the penetration time.

[0058] This can also be achieved with a thicker layer of material, but from an environmental and economic perspective, a thicker layer does not seem to be very advantageous.

[0059] For example, for bottles, beakers, and trays made of polymers, the material thickness is typically several hundred micrometers, so the permeation time of the compound is particularly important.

[0060] Therefore, materials with good functional barrier properties, such as polymer compositions (A) and multilayer composite structures (S) including at least one such polymer layer (S1), represent a technically cost-effective option. The use of compositions that allow compounds (such as stabilizers) to migrate slowly is even more advantageous.

[0061] In composition (A), compounds such as stabilizers have low diffusion coefficients (DFB) and low mobility. If the diffusion coefficient of the material at a given temperature is known, the permeation time can be calculated.

[0062] Figure 3 This demonstrates the qualitative contribution of material selection to the functional barrier effect. It features a low polymer specific constant (A... PThe polymer exhibits low diffusion coefficients (DFB) and correspondingly long permeation times (θ). The low solubility of organic molecular moieties (e.g., stabilizers) in the polymer (cFB) results in low concentrations of the compound in the plastic, leading to high partition coefficients (KP, FB). The linear region of the curve has a correspondingly flat profile, resulting in only low migration levels (mt) even over long periods.

[0063] Figure 3 The diffusion coefficient (DFB) describes, on the one hand, the rate at which a compound migrates into the plastic. On the other hand, the partition coefficient (KP, FB) describes the relative solubility of the compound between adjacent layers / layers in a composite structure (e.g., in the case of packaging). Based on these two coefficients, the functional barrier properties of the polymer composition (A) relative to other components (e.g., mineral oil) in multilayered composite structures (S1, S2, etc.) or packaging material systems can be estimated.

[0064] Figure 4 The quantitative migration of mineral oil (ODP) in polymers general-purpose polystyrene (GPPS), HIPS, LD polyethylene, polypropylene, and PET was shown (0.2% by weight of ODP in each case, 10 days at 40°C, and a layer thickness of 0.25 mm). It is evident that polyethylene and polypropylene exhibit poor migration barrier properties, while polystyrene and HIPS may demonstrate good migration barrier properties even at lower layer thicknesses.

[0065] Figure 5 The limiting thickness (“infinite thickness”, CF, t) of various polymeric material films is shown, namely polystyrene (GPPS, HIPS), PET, polypropylene, and LD polyethylene (in each case, ODP is 0.2 wt%, layer thickness is 0.25 mm at 40 °C for 10 days). It is clear that for polyethylene and propylene, a high polymer layer thickness is necessary for a migration barrier, while polystyrene achieves a good migration barrier even in the micrometer range of the layer.

[0066] The present invention generally relates to a thermoplastic polymer composition (A) having reduced migration properties. It comprises a polymer composition (A) having at least one thermoplastic polymer (P) having migration-blocking properties, particularly for a stabilizer, and at least one stabilizer component (S) and / or at least one other component (I), such as a monomer (e.g., styrene) or an oligomer (e.g., a trimer, etc.). The conditions suitable for the thermoplastic polymer composition (A) are as described above.

[0067] When the thermoplastic polymer (P) is in a two-phase state, it has a high A P and a higher diffusion coefficient (D PThe polymer component (PP) is embedded as a discontinuous phase in the form of particles with a weight-average particle size (D) of 20 nm to 10 μm, which has a low A P In polymer components (PM) with lower diffusion coefficients (CP).

[0068] Thermoplastic polymers (P) do not have a cocontinuous structure: they are either a single-phase homogeneous phase or a two-phase heterogeneous phase.

[0069] The thermoplastic polymer (P) is preferably polystyrene or polystyrene / SBC blends, especially without a cocontinuous structure. Examples of cocontinuous structures include "bicontinuous bis-diamond" structures, cylindrical structures (e.g., polybutadiene cylinders in a polystyrene matrix), layered structures (e.g., thin layers of polybutadiene within a polystyrene matrix), and interpenetrating network (IPN) structures.

[0070] The glass transition temperature (Tg) of the thermoplastic polymer (P) is preferably above 50°C, usually above 60°C, and more particularly above 70°C.

[0071] The polymer is typically used in the range of room temperature (20°C), or in the range of cooling (-20°C) to normal transport temperature (e.g., 40°C, up to 50°C).

[0072] The polymer ratio constant (A) of thermoplastic polymers (P) P It is preferred to be less than 1.0, for example -2.0 to 0.95, and more particularly -1.8 to 0.93.

[0073] Mineral oil diffusion coefficient (D) of thermoplastic polymers (P) P At 20℃, it is preferably less than or equal to 10-12 cm. 2 / s.

[0074] Suitable thermoplastic polymers (P) include not only single-phase standard polystyrene (GPPS, i.e., general-purpose polystyrene, manufactured by companies such as INEOS Styrolution), but also impact-resistant polystyrene, such as HIPS (high-impact polystyrene, manufactured by companies such as INEOS Syrollution). Blends of PS and SBS copolymers or blends of PS and SBC copolymers are also frequently used to meet the above criteria.

[0075] The at least one stabilizer component (S) is selected from, for example, antioxidants and light stabilizers.

[0076] In one embodiment, the migration-reducing thermoplastic polymer composition (A) comprises 50 to 99.9% by weight of at least one thermoplastic polymer (P) based on the polymer composition (A), and 0.1 to 2.0% by weight of at least one stabilizer component (S) and / or at least one other component (I) based on the polymer composition (A).

[0077] The polymer composition (A) typically contains 70 to 99% by weight of at least one thermoplastic polymer (P), or typically contains a mixture of two or more polymers, such as polystyrene and styrene copolymers (e.g., SB copolymers).

[0078] In another embodiment, the thermoplastic polymer composition (A) with reduced migration of the stabilizer (S) and / or another component (I) comprises a thermoplastic polymer (P) containing a styrene polymer having a glass transition temperature (Tg) of at least 60°C, more particularly at least 70°C, and (optionally) at least one antioxidant additive as the stabilizer component (S), in an amount based on the polymer composition (A) up to 5% by weight, particularly 0.1 to 2.0% by weight, typically 0.1 to 1.0% by weight.

[0079] Thermoplastic polymers (P) are typically styrene-containing polymer components, preferably selected from polystyrene (PS), more particularly HIPS and GPPS, or blends of styrene-containing polymer components and S / B block copolymers, such as SBS copolymer / PS blends or SBC copolymer / PS blends, such as PS-SBC blends.

[0080] The stabilizer component (S) preferably contains at least one stabilizer selected from antioxidants.

[0081] Such antioxidants possess, for example, one or two or more space-protected phenolic OH groups, and / or phosphite units and / or sulfur compounds. Examples of suitable antioxidants include:

[0082] ·2,6-Di-tert-butyl-p-cresol

[0083] ·2,2'-Methylenebis(4-methyl-6-tert-butylphenol)

[0084] ·2,2'-Methylenebis-(4-methyl-6-cyclohexylphenol)

[0085] ·2,2'-Methylenebis(6-tert-butyl-4-ethylphenol)

[0086] ·Octadecanoyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

[0087] Pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)

[0088] ·Octyl 3,5-di-tert-butyl-4-hydroxycinnamate

[0089] Triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate

[0090] ·Thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]

[0091] ·N,N'-hexane-1,6-dimethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)]

[0092] ·6,6'-Di-tert-butyl-4,4'-butene di-m-cresol

[0093] ·1,3,5-Trimethyl-2,4,6-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene

[0094] ·2,4-Bis(octylthio)-6-(4-hydroxy-3,5-di-tert-butylaniline)-1,3,5-triazine

[0095] 2-Methyl-4,6-bis(octylsulfonylmethyl)phenol

[0096] Phenol, 4-methyl, reaction products dicyclopentadiene and isobutylene

[0097] ·1,2-Di[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine

[0098] ·3,3'-Bis(3,5-di-tert-butyl-4-hydroxyphenyl)-n,n'-bispropionamide

[0099] ·2-(1,1-dimethylethyl)-6-[[3-(1,1-methylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylphenylacrylate

[0100] ·2-(1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl)-4,6-di-tert-pentylphenyl acrylate

[0101] ·2-tert-butyl-6-methyl-4-[3-(2,4,8,10-tetratert-butylbenzo[d][1,3,2]benzodioxophosphoric-6-yl)oxypropyl]phenol

[0102] ·2-(1,1-dimethylethyl)-6-[[3-(1,1-methylethyl)-2-hydroxy-5-methylphenyl]methyl]-4-methylphenylacrylate

[0103] ·1,3,5-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-diazine-2,4,6(1H,3H,5H)-trione

[0104] ·4,4',4”-(1-methylpropyl-3-ylidene)tris(6-tert-butyl-m-cresol)

[0105] ·3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxane[5.5]undecane

[0106] ·4,4'-Thiobis(2-tert-butyl-5-methylphenol)

[0107] · Ethylene bis[3,3-bis[3-(1,1-dimethylethyl)-4-hydroxyphenyl]butyrate]

[0108] ·2,4-Dimethyl-6-(1-methylpentadecanyl)phenol

[0109] Hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]

[0110] TNPP (trinonylphenyl) phosphite

[0111] Diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate

[0112] ·Calcium diethylbis[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-methyl]phosphonate]

[0113] Tocopherol

[0114] Tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate

[0115] ·3-tert-butyl-2-hydroxy-5-methylphenyl sulfide

[0116] ·4-[[4,6-bis(n-octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol

[0117] 3,5-bis(1,1-dimethylethyl)-4-hydroxyC13-15-alkyl ester of phenylpropionic acid

[0118] Tris(2,4-di-tert-butylphenyl) phosphite

[0119] Other organophosphorus stabilizers.

[0120] Preferred examples of stabilizers used are:

[0121] 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenylprop-2-enoate;

[0122] TNPP (trinonylphenyl) phosphite.

[0123] Examples of other preferred ingredients are:

[0124] White oil, lubricant, styrene oligomers.

[0125] Combinations of different stabilizers are often used, in which case, based on the polymer composition (A), it is preferred to use a total of up to 2.0% by weight of stabilizers.

[0126] Furthermore, the present invention relates to a composite structure, more particularly suitable for packaging applications, comprising at least two distinct layers, wherein at least one layer (S1) is composed of the thermoplastic polymer composition (A) as described above, wherein the migration of stabilizers is reduced.

[0127] In the case of packaging applications, this layer (S1) is preferably oriented inwards, for example, for contact with food.

[0128] In one embodiment, the composite structure comprises at least two distinct layers, wherein at least one layer (S1) is composed of a migration-reduced thermoplastic polymer composition (A), together with a second layer (S2), and optionally other layers S3, S4, S5, the composite structure being adapted to provide a packaging material with enhanced anti-delamination properties.

[0129] The present invention further relates to a method for producing a thermoplastic polymer composition (A) with reduced migration, wherein at least one thermoplastic polymer (P) having stabilizer migration blocking properties is mixed with a stabilizer component (S) and optionally other polymer additives (different from component (S)). Various methods of mixing or blending thermoplastic compositions with additives are known to those skilled in the art. The stabilizer component may also be introduced into the composition in masterbatch form.

[0130] Similar to functional barriers within materials or articles, the concept of functional barriers in this invention can be extended to the entire packaging system. For this purpose, it is helpful to interpret the packaging system as concentric layers that at least partially surround each other. In this case, materials or articles may not be in direct contact with each other under certain circumstances; for example, air or other gases may be present between them.

[0131] Article 1 of EU Regulation (EC) No. 1935 / 2004 of October 2004 applies to materials and articles (including active and intelligent food contact materials and articles) that are intended to come into contact with food in the finished state, or have already come into contact with food, or that are reasonably expected to come into contact with food or transfer their components into food under normal or foreseeable use.

[0132] According to the present invention, it has also been investigated which polymer materials or products (e.g., inner bags, which may be used to package sensitive contents (e.g., food) have good functional barrier properties relative to other materials located further outside (e.g., temporary packaging made of recycled cardboard or polymers).

[0133] Studies can be conducted in a similar manner, for example, to determine whether the film or molded form (tray) of the aforementioned polymer composition possesses functional barrier properties relative to compounds from the applied label, or whether the matrix composed of the polymer composition provides an effective functional barrier against compounds (e.g., photoinitiators, stabilizers) from the applied printing ink. The time required for a compound to migrate from the outside (e.g., outer packaging or printing ink) through the functional barrier (e.g., main packaging or matrix) is also known as the penetration time θ. According to Equation 4, this penetration time is directly proportional to the thickness dP of the inner bag and inversely proportional to the diffusion coefficient DFB of the compound in the functional barrier (FB):

[0134]

[0135] The mode of action of functional barriers is also Figure 1 and Figure 2 The figure in the diagram shows the change in migration (mF, t / a) relative to time (t).

[0136] When no functional barrier or migrating compounds are present in the food contact layer, an effect similar to [previous observation] was observed. Figure 1 The graph corresponds to the migration time curve. If the migration of the compound is determined at two arbitrary time points, and if the two points are connected by a straight line, the line will always intersect the y-axis with a positive value (I>0) (migration, mF, t / A).

[0137] If a functional barrier exists, the observed migration time curve corresponds to Figure 2The graph shows the migration of the compound. If the migration of the compound is determined at two arbitrary time points, and if these two points are connected by a straight line, the line will intersect the y-axis with a negative value (I<0) if one of the time points is within the infiltration time θ (hysteresis time) (migration, mF, t / A). A functional barrier (FB) composed of polymers is effective relative to the compound if the infiltration time θ is as long as possible. During the infiltration time, the compound will not transfer / migrate from the outside of the FB into the contents. This can be achieved with thick layers, but thick layers are not very advantageous from the perspective of resource conservation and economic efficiency.

[0138] For example, it is not uncommon for polymer-made bottles, beakers, and trays to have material thicknesses of several hundred micrometers. Consequently, the permeation time of the compound is longer than that of a thin film with the same material composition.

[0139] In the flexible packaging industry, using materials such as glass or metal as an absolute barrier to compound migration seems to be only a hypothetical choice due to numerous disadvantages.

[0140] Materials with functional barrier properties, such as the polymers and multilayer composites mentioned above, represent a technologically feasible and inexpensive option. It is advantageous to use materials where the compound can only pass through / migrate very slowly. In barrier materials, the compound has a low diffusion coefficient (DFB), i.e., low mobility. In some cases, the diffusion coefficient can be found in the literature or estimated using scientifically accepted methods. If the diffusion coefficient of the compound in the material at a given temperature is known, the penetration time can be calculated using the equations described above.

[0141] In the context of this invention, the qualitative contribution of material selection to the functional barrier effect is revealed. Materials with low polymer specific constants (A...) P The polymer exhibits a low diffusion coefficient (DFB) and a correspondingly long permeation time θ. The low solubility of the migrating agent (e.g., an organic additive) in the polymer (cFB) results in a low concentration of the additive in the polymer, leading to a high partition coefficient (KP, FB). The linear region of the curve has a correspondingly flat profile, thus resulting in low migration levels (mt) even after a long period.

[0142] Figure 3 The "diffusion coefficient" constant (DFB) is described. It describes the rate at which a compound migrates into the polymer. Alternatively, the "partition coefficient" (KP, FB) is described, which describes the relative solubility of a compound (e.g., an additive) between adjacent layers in a composite system (e.g., packaging). Based on these two coefficients, the functional barrier properties of the polymer to additives (e.g., mineral oils or stabilizers) in a multilayer composite structure or packaging material system can be calculated or estimated. Therefore, the functional barrier effect on migratable compounds can be determined.

[0143] Figure 4 The varying solubility of the additive (0.2% ODP) in various polymers (cFB) and the associated migration rates (10 days at 40°C) are described. This is particularly low in the cases of styrene-containing polymers GPPS and HIPS. The K value is the partition coefficient of the migrating additive in the polymer and food simulant (solvent) system. The K value (more precisely, K...) P / L A K value of 1 means that the migrating additive (e.g., ODP) is in equilibrium at 1, meaning it is present in the polymer more than in the solvent. In the presence of 50% ethanol, the K value for PE and PS tends to be 1.

[0144] Figure 5 The “infinite thickness” (with 0.2% ODP additive; 10 days at 40°C) of various polymers (polystyrene, PET, polypropylene, and LD polyethylene) is described, with particularly low thickness in the case of styrene-containing polymers (e.g., PS).

[0145] The glass transition temperature (Tg) of polymers has also proven important for the barrier effect against polymer additive migration. Polypropylene (EPP) is a particularly tough foam made from expanded polypropylene, typically foamed on-site by the user. Due to PP's low Tg (5°C), chain migration in PP is very high at room temperature, causing PP granules filled with a blowing agent (such as pentane) to lose the blowing agent within a very short time (during storage or transportation). Conversely, manufacturers can pack EPS (expandable polystyrene) granules with pentane as the blowing agent, without significant loss of pentane during storage and transportation. This is because polystyrene has a high Tg; even when mixed with 5% pentane, its Tg only drops to around 80°C, sufficient to prevent chain migration at room temperature.

[0146] Other suitable additives include:

[0147] The other light stabilizers used can be any conventional light stabilizers, such as compounds based on benzophenone, benzotriazole, cinnamic acid, and hindered amines (HALS).

[0148] Lubricants include hydrocarbons, such as oils, paraffin waxes, PE waxes, PP waxes, fatty alcohols and ketones with 6 to 20 carbon atoms, carboxylic acids, such as fatty acids, montmorillonite or oxidized PE waxes, carboxamides, and carboxylic acid esters, such as ethanol, fatty alcohols, glycerol, ethylene glycol, and pentaerythritol as their alcohol components, and long-chain carboxylic acids as their acid components. The stabilizers used can be conventional antioxidants, such as phenolic antioxidants, such as alkylated monophenols, β-(3,5-

[0149] Esters and / or amides of di-tert-butyl-4-hydroxyphenyl)propionic acid and / or benzotriazole. (Tritinylphenyl) phosphite is also frequently used. Antioxidants are also described in EP-A 698637 and EP-A 669367 and mentioned in the Handbook of Plastic Additives (H. Zweifel, Munich, 2009). For example, phenolic antioxidants used may be 2,6-di-tert-butyl-4-methylphenol, pentaerythritol [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], and N,N'-di-(3,5-di-tert-butyl-4-hydroxyphenylpropyl)hexamethylenediamine. The stabilizers may be used alone or in combination.

[0150] The polymer composition (A) of the present invention can be granulated or processed by known methods such as extrusion, injection molding or calendering to form films, hoses, fibers, profiles, footwear shells, molded technology parts, utilitarian articles, various molded parts, coatings and / or blow molded parts.

[0151] The present invention will be described in more detail below with reference to embodiments, accompanying drawings and claims. Example

[0152] To illustrate the technical advantages of this invention, the migration of three different additives was studied:

[0153] Antioxidant 1: Phenolic stabilizer of Sumilizer GM (produced by Sumitomo Chemical Co., Ltd., Japan): 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenylprop-2-enoate;

[0154] Antioxidant 2: TNPP (phosphite stabilizer), (trinonylphenyl) phosphite;

[0155] Mineral oil: Commercial white oil (plasticizer, such as products from Eni Oilproducts).

[0156] The following polymers were used:

[0157] SBS1: Styrolux 3G55 (product of INEOS Styrolution in Frankfurt) is a coupling (star-shaped) SBS polymer with the following composition:

[0158] 74% styrene / 26% butadiene.

[0159] Polystyrene 158 (product of INEOS Styrolution in Frankfurt, standard PS, Vicat B / 50 at 101°C, without white oil).

[0160] 2.5% by weight mineral oil (white oil DAB 10); 0.25% by weight antioxidant 1 (“Sumilizer GM”); and 0.4% by weight antioxidant 2 (trinonylphenyl phosphate (TNPP)) were added as stabilizers / ingredients.

[0161] SBS+PS

[0162] In addition, a mixture of polymer component SBS1 and polystyrene 158 (standard PS from INEOS Styrolution in Frankfurt, Vicat B / 50 at 101°C, without white oil) was also prepared.

[0163] These mixtures were prepared by mixing on a twin-screw extruder ZSK30 (Coperion) at a melt temperature of approximately 240°C:

[0164] • SBS1+25%PS means: a blend of 75% by weight Styrolux 3G55 and 25% by weight polystyrene 158 (stable form: a two-phase blend with a layered / cylindrical structure);

[0165] •SBS1+50%PS refers to: a blend of 50% by weight Styrolux 3G55 and 50% by weight polystyrene 158 (the morphology is mainly composed of PS as a homogeneous and continuous phase and polybutadiene-styrene copolymer as a discontinuous phase, dispersed in particles, with some visible layers).

[0166] •SBS1+75%PS refers to: a blend of 25% by weight Styrolux 3G55 and 75% by weight polystyrene 158 (in stable form, PS is a homogeneous, continuous phase, while the polybutadiene-styrene copolymer is a discontinuous phase, dispersed in particles).

[0167] The morphology was determined by conventional scanning electron microscopy at 100,000x magnification based on ultrathin sections compared with RuO4.

[0168] Migration measurement:

[0169] Using oil as a fat mimic is unsuitable due to analytical difficulties, and 95% ethanol and isooctane are also not very instructive as fat mimics because they interact highly with the polymer matrix. Aqueous mimics are difficult to develop due to the low solubility of additives.

[0170] For these reasons, migration cells were used, which hold polymer membranes composed of the following polymers:

[0171] “SBS1”

[0172] “SBS + 25% PS”

[0173] “SBS+50%PS”, and

[0174] “SBS+75%PS”

[0175] Each layer was 1 mm thick (see Table 3), and in each case, it was between two 0.5 mm thick polyethylene films (LDPE). Blank migration values ​​of the polyethylene (LDPE) were determined. Following ether extraction, the amount of migrated material was determined by FID gas chromatography (after the times and temperatures shown in Table 3a).

[0176] Table 3

[0177] column: DB1ht, 30m, inner diameter 0.25mm, thin film 0.1μm Carrier gas / flow rate: Helium; 1.6 ml / min; 35 cm / s Injector: Split type / non-split type; 320℃ injection: 1μm without cracks Detector: FID; 320℃ Temperature program: 60℃ (2 minutes) 20℃ / minute 320℃

[0178] Table 3a shows the kinetic measurements of component migration (in μg / dm2 at 40-70 °C) in SBS and SBS+25%PS, as well as other blends according to the invention (SBS+50 and +75%PS).

[0179] Diffusion coefficient D p The migration values ​​are determined by the corresponding polymer matrix and the corresponding migrating agent, and used in Equation (1) to determine the migration characteristics.

[0180] Table 3a

[0181]

[0182] The diffusion coefficient D is determined based on the migration values ​​of the corresponding polymer matrix and the corresponding migrating agent. p And calculate A using equation (2). p Value; see also

[0183] Table 3b.

[0184]

[0185] nd indicates not measured

[0186] Mineral oil causes the soft phase of the discontinuous polymer to expand and, in the boundary regions, causes the discontinuous (particulate) morphology of the present invention to exhibit a partially layered morphology, which is accompanied by unfavorable technical effects. This is evident, for example, in compositions containing 50 wt% polystyrene and 50 wt% Styrolux 3G55 as polymer components.

[0187] This invention discovers that during the transition from a (co-continuous) polymer structure to a discontinuous particulate structure in the composition (A) of this invention, the migration value and polymer ratio constant A... PAll showed a significant reduction. This indicates an increased barrier effect in the polymer composition, thus the polymer composition (A) according to the present invention reduces stabilizer (or component) migration, resulting in a significant technical advantage.

[0188] Among other applications, the technology of this invention can be used to produce packaging with a composite structure having two different layers, one layer (S1) consisting of a thermoplastic mixture of 25% by weight of styrene-butadiene-styrene copolymer and 75% by weight of PS, and the other layer (S2) consisting of a styrene-free thermoplastic, more particularly polyurethane or PET.

Claims

1. A thermoplastic polymer composition (A) for reducing the migration of stabilizer (S) and / or other components (I), comprising 50-99.9% by weight of at least one thermoplastic polymer (P) having stabilizer migration blocking properties, at least 0.1% by weight based on the polymer composition (A), at least one stabilizer component (S), and / or at least 0.1% by weight based on the polymer composition (A), wherein for the thermoplastic polymer component (A): a) The glass transition temperature (Tg) of the thermoplastic polymer (P) is higher than the service temperature. b) The polymer ratio constant (AP) of the thermoplastic polymer (P) is less than 1, and c) At 20°C, the mineral oil diffusion coefficient (DP) of the thermoplastic polymer (P) is less than 10. -12 cm 2 / s, and d) Thermoplastic polymers (P) exist in a two-phase heterogeneous state. in, In the case of a two-phase heterogeneous state of thermoplastic polymer (P), it has a high A P and a higher diffusion coefficient (D P The polymer component (Pp) exists as a discontinuous phase in the form of particles with a weight-average particle size (D) of 20 nm to 10 µm, and is embedded in a lower A P and a lower diffusion coefficient (D P In the polymer component (Pm), Thermoplastic polymers (P) do not have a co-continuous structure.

2. The thermoplastic polymer composition (A) according to claim 1, characterized in that, It comprises, based on polymer composition (A), at least 70 to 99% by weight of at least one thermoplastic (P).

3. The thermoplastic polymer composition (A) according to claim 2, characterized in that, It comprises at least one stabilizer component (S) based on polymer group (A), 0.1 to 2.0 wt% of polymer composition (A), and / or at least one additional component (I) based on polymer composition (A) 0.1 to 2.0 wt%.

4. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, It contains, as a thermoplastic polymer (P), a styrene-containing polymer, having a glass transition temperature (Tg) of at least 60°C.

5. The thermoplastic polymer composition (A) according to claim 4, characterized in that, The glass transition temperature (Tg) of the styrene-containing polymer is at least 70°C.

6. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, It contains a styrene-containing polymer component as a thermoplastic polymer (P), selected from polystyrene (PS), SBS copolymer / PS blends, and SBC copolymer / PS mixtures.

7. The thermoplastic polymer composition (A) according to claim 6, characterized in that, The polystyrene (PS) is selected from HIPS and GPPS.

8. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, It contains polystyrene (PS) and SBS copolymer as thermoplastic resin (P).

9. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, The thermoplastic resin (P) comprises at least 50% by weight of polystyrene (PS) and at least 10% by weight of SBS copolymer.

10. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, It contains at least one stabilizer component (S) selected from antioxidants and light stabilizers, and / or contains at least one other component (I) selected from residue monomers and oligomers.

11. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, Based on polymer composition A, which contains 0.1 to 2.0% by weight of at least one stabilizer component (S).

12. The thermoplastic polymer composition (A) according to claim 11, characterized in that, The at least one stabilizer component (S) is at least one antioxidant.

13. The thermoplastic polymer composition (A) according to at least one of claims 1 or 2, characterized in that, Based on the weight of the polymer composition, it contains 0.1 to 2.0% by weight of two different stabilizer components (S).

14. The thermoplastic polymer composition (A) according to claim 13, characterized in that, The thermoplastic polymer composition (A) also contains at least one other component.

15. A composite structure for packaging comprising at least two distinct layers, wherein at least one layer (S1) comprises a thermoplastic polymer composition (A) having reduced migration as described in at least one of claims 1 or 2.

16. The composite structure for packaging as claimed in claim 15, comprising at least two distinct layers, wherein at least one layer (S1) is primarily composed of a thermoplastic polymer composition (A) of polystyrene (PS), an SBS copolymer / PS blend, and / or an SBC copolymer / PS blend, and at least one additional layer (S2) is primarily composed of a styrene-free thermoplastic polymer composition (A2).

17. A method for producing a thermoplastic polymer composition (A) as claimed in any one of claims 1 or 2, said thermoplastic polymer composition (A) having reduced migration of stabilizer (S) and / or other components (I), wherein at least one thermoplastic polymer (P) having migration-blocking properties is mixed with at least one stabilizer component (S).

18. The method of claim 17, wherein another polymer additive is also mixed with the at least one thermoplastic polymer (P) having migration barrier properties and the at least one stabilizer component (S).

19. Use of a thermoplastic polymer composition (A) having reduced migration of stabilizer (S) and / or other components (I) as described in any one of claims 1 or 2 in the preparation of films, fibers or molded articles.

20. Use of the composite structure as claimed in claim 15 for providing packaging with enhanced anti-delamination properties, wherein the composite structure comprises at least two distinct layers, wherein at least one layer (S1) is composed of a thermoplastic polymer composition (A) having reduced migration properties.

21. Use of the composite structure as claimed in claim 16, wherein the composite structure comprises at least two distinct layers, wherein at least one layer (S1) is primarily composed of a thermoplastic polymer composition (A) being polystyrene (PS), an SBS copolymer / PS blend, and / or an SBC copolymer / PS blend, and at least another layer (S2) is primarily composed of a styrene-free thermoplastic polymer composition (A2) for providing packaging with enhanced anti-delamination properties.

22. A method for producing a composite structure comprising at least two distinct layers, wherein at least one layer (S1) is composed of a thermoplastic polymer composition (A) having reduced migration as described in at least one of claims 1 or 2, the method comprising providing said layer (S1) and at least one additional layer (S2) and connecting said at least two layers.

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