EP3880458A1

EP3880458A1 - Multiple wall comprising a microcellular structure

Info

Publication number: EP3880458A1
Application number: EP19824258.8A
Authority: EP
Inventors: Andrea KEMENY; Mike KONDZIELA
Original assignee: Kulzer GmbH; Kulzer and Co GmbH
Current assignee: Kulzer GmbH
Priority date: 2018-12-12
Filing date: 2019-12-11
Publication date: 2021-09-22
Also published as: WO2020120558A1; US20220017286A1; DE102018132007A1

Abstract

The invention relates to a multiple wall, in particular of thermally insulated hollow bodies or containers (30), the multiple wall (20) comprising at least one inner layer (21), a barrier layer (22) and an outer layer (23), said barrier layer (22) being designed to form a barrier for oxygen and/or steam; the inner layer (21) and/or the outer layer (23) has or have a microcellular structure (24); the microcellular structure (24) has fluid bubbles (25) and the fluid bubbles (25) are the product of a foaming agent that is physically and/or chemically introduced.

Description

Multi-layer wall with a microcellular structure

The invention relates to a multi-layer wall with a microcellular structure. The invention further relates to a method for producing a multilayer wall with a microcellular structure and to the use of a multilayer wall.

In dental applications, so-called bonds are used as adhesion promoters between the tooth cavity and the restoration material. Typical packaging for bonds is 5 ml plastic bottles for multiple applications. Formulations for bonding products can contain a larger proportion of acetone. A disadvantage of formulations containing acetone is the so-called overcooking behavior. When the bottle is held / pressed, heat is entered into the plastic bottle by the user's hand. This heat is also transferred to the acetone-containing formulation. Acetone has a very low vapor pressure, which causes the formulation to boil when the heat is applied.

The poor thermal conductivity of the plastic is currently used to reduce the transfer of body heat into the bonding. The thicker the wall of the plastic bottle, the lower the thermal conductivity of the plastic bottle. A bottle with a large wall thickness has a higher rigidity. This means that the user has to press the bottle harder when squeezing out the liquid. Accurate dosing is therefore difficult and represents a competitive disadvantage.

The object of the invention was to improve the thermal insulation effect of the side walls. A particular focus was on improving the thermal insulation effect of side walls, such as the wall of containers or hollow bodies, which serve for the storage and optional application of a liquid, solvent-containing composition. In particular, overcooking should be avoided when handling an acetone-containing solution in a container. Likewise, the thermally insulated side wall should also be usable for the production of containers or hollow bodies for the storage and / or transport of a wide variety of goods or compositions, such as paints, varnishes, adhesives, foods, solvent-containing compositions and / or cosmetics, such as nail gels etc.

The object is achieved by a multilayer wall, the multilayer wall comprising at least one inner layer, a barrier layer and / or an outer layer, the barrier layer being designed to be a barrier to oxygen and / or To form water vapor, wherein the inner layer and / or the outer layer has a microcellular structure, the microcellular structure having fluid bubbles, and wherein the fluid bubbles are the product of a physically and / or chemically introduced propellant. Preferably used as the multilayer wall for the production of containers or hollow bodies, in particular of three-dimensional hollow bodies in the form of shaped bodies, particularly preferably of elastic or plastically deformable hollow bodies. The containers or hollow bodies obtainable in this way are thermally insulated containers or thermally insulated hollow bodies.

The multilayer wall is advantageously elastically pronounced and has an improved thermal insulating effect.

The multilayer wall is designed to form at least one side wall of a container, the multilayer wall comprising at least one inner layer, a barrier layer and an outer layer, the barrier layer being designed to form a barrier for oxygen and / or water vapor, the inner layer and / or the outer layer has a microcellular structure, the microcellular structure having fluid bubbles, and wherein the fluid bubbles are the product of a physically and / or chemically introduced propellant.

A container can be selected from a bottle, a tube, a single-dose vial, a multi-dose vial, a bag, sachet, can with lid and / or a syringe body. A tube is understood to be an elongated, mouldable container which can generally hold pasty or viscous compositions.

The multilayer wall is designed to form the side wall, a bottom and a discharge area of a container, the multilayer wall comprising at least one inner layer, a barrier layer and an outer layer, the barrier layer being designed to form a barrier to oxygen and / or water vapor , wherein the inner layer and / or the outer layer has a microcellular structure, wherein the microcellular structure has fluid bubbles, and wherein the fluid bubbles are the product of a physically and / or chemically introduced propellant.

This advantageously provides a container, in particular a bottle or tube, with a foamed multilayer wall, which has a considerable weight saving and a better thermal insulation effect compared to compact blow molded parts. In particular, the foamed plastic bottle has a lower thermal conductivity. The foamed multi-layer wall can be designed in such a way that the heat input by the user into the bonding is reduced so that boiling over of formulations containing acetone, for example, no longer occurs.

Under a bottle is a bottle with a bottom for storage, as well as a bottle that is provided with additional means or requires a separate holder to form a vertical stability of the bottle, such as a bottle with a side wall comprising a lower area of the bottle, for storage and optional application of a liquid, solvent-containing composition to understand. The bottle can be closed with a lid, attachment or other closure means.

When using only physically introduced blowing agents - as in the patented MuCell process - the multi-layer wall shows no residues of degradation products in the finished component. MuCell foamed parts can be recycled in their original polymer group, because the chemistry of the plastic is not changed.

A microcellular structure with essentially closed cells denotes a material which, at a thickness of approximately 200 pm, contains no connected cell passage through the material. A microcellular structure therefore has no continuous channels.

Fluid bubbles in microcellular structures contain a fluid. The fluid (from the Latin fluidus for "flowing") is a common name for gases and liquids.

Thermal insulation and density reduction of the microcellular structure are in the ratio 1.5: 1. The greater the thickness of the microcellular structure, the lower the relative density. The thermal insulation effect increases with decreasing density. The stiffness usually increases with the cubic number of the wall thickness.

By using a microcellular structure, the density of the wall of the container is reduced by 35 to 40% compared to an identically constructed container made of non-foamed polymers. The weight reduction of the bottle according to the invention is 20 to 30%. The stiffness is a linear function of the change in density.

The barrier layer between the inner and outer layers ensures that no oxygen and / or water vapor can enter or leave the container. This prevents undesirable reactions of the composition in the container with air and / or water vapor. For example, no skin can form with compositions containing acetone.

According to one embodiment, the blowing agent in the microcellular structure has inert gas, in particular nitrogen, gaseous carbon dioxide and / or a mixture of at least two of the gases mentioned.

Any of a wide variety of physical blowing agents known to those skilled in the art, as well as hydrocarbons, chlorofluorocarbons, nitrogen, carbon dioxide, argon, and the like, and mixtures can be used in connection with the invention. According to a preferred embodiment, a source provides carbon dioxide or nitrogen or a mixture thereof as a blowing agent. Supercritical fluid blowing agents are preferred, especially supercritical carbon dioxide and / or nitrogen. In particularly preferred embodiments, only carbon dioxide or nitrogen is used in each case. Where a supercritical fluid blowing agent is used, a single phase solution of polymer material and blowing agent is created.

According to one embodiment, it is provided that the multilayer wall forms the container completely. Alternatively, the multi-layer wall can partially form the container.

Where the container, in particular the bottle, has the polymer-foamed microcellular structure, the bottle advantageously has a lower thermal conductivity. With the same wall thickness compared to the non-foamed polymer component, the heat transfer from the user's hand into the bonding is reduced in the foamed part of the bottle. The wall thickness in the foamed area can be selected so that the rigidity is not too high and pressing the bottle to dispense the bonding out of the bottle is not too difficult.

According to one embodiment, the microcellular structure has a void volume, i.e. the void volume of the microcellular structure, from less than 50% and greater than 10%. The void volume of the microcellular structure is preferably from 10% to 60% by volume in relation to the total volume of the inner layer and / or outer layer comprising the microcellular structure.

With this invention, microcellular structure can be produced synonymously with microcellular foam over a wide range of densities. In preferred In embodiments, the void volume is greater than 10%, in particularly preferred it is greater than or equal to 20%, and a microcellular structure with greater than or equal to 50% is also preferred. In further embodiments, the microcellular structure, like the microcellular foam, has a void volume of less than or equal to 50%, preferably less than or equal to 30%. In a particularly preferred embodiment, microcellular structure, such as the microcellular foam, has a void volume of 10% to 50%. Microcellular structures within this preferred void volume range (from 10% to 50% volume percent based on the total volume of the inner layer and / or outer layer comprising the microcellular structure) show excellent mechanical properties as well as tensile strength and tensile modulus, while still showing a significant reduction the density compared to solid plastic.

According to one embodiment, the percentage by weight of inert gas, in particular nitrogen, and / or carbon dioxide, based on the total weight of 100% by weight of the microcellular structure of the inner layer and / or the outer layer, is from 0.20% by weight to 2.5% .-%, preferably from 0.20 wt .-% to 0.90 wt .-%.

The percentage by weight of inert gas is therefore relatively low. The chemical resistance of the multi-layer wall is largely present.

According to one embodiment, it is provided that the diameter of the fluid bubbles is less than or equal to 300 pm, in particular less than or equal to 200 pm, preferably less than or equal to 100 pm, particularly preferably less than or equal to 50 pm.

The cell size of the microcellular structure depends on the percentage by weight of the inert gas and the type of material. In general, it can be stated that the higher the percentage by weight of inert gas, the smaller the cell size.

In one embodiment, the barrier layer comprises an ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC) optionally laminated with polychlorotrifluoroethylene (PCTFE).

The barrier layer preferably comprises an ethylene-vinyl alcohol copolymer.

Ethylene-vinyl alcohol copolymer, abbreviation EVOH, occasionally also EVAL, is a copolymer that is formally composed of the monomers ethene and vinyl alcohol. Ethylene-vinyl alcohol copolymer is generally used for packaging food and, more recently, for the manufacture of tank containers in the automotive industry. Of the The primary use is to create a barrier to keep out oxygen in food and carbon dioxide in tank containers. Ethylene-vinyl alcohol copolymer is either extruded or laminated as a thin layer on cardboard, film, or other plastics. The properties of the copolymer depend on the proportion of ethene in the copolymer. Low ethene fractions lead to a copolymer with improved separation properties, higher ethene fractions lower the processing temperature (softening temperature) of the copolymer.

Polyethylene vinyl alcohol (abbreviation: EVOH) has very good barrier properties, both against oxygen and against water vapor. Dense EVOH offers the best solution, especially for sensitive solutions in a container

Cycloolefin copolymers (COC) are obtained by metallocene-catalyzed copolymerization of cycloolefins (such as norbornene) with alk-1-enes (such as ethene). Common to all COCs are a number of properties such as good thermoplastic flowability, high rigidity, strength and hardness as well as low density and high transparency with good acid and alkali resistance. In the field of medicine / diagnostics, the excellent biocompatibility, in particular blood tolerance and the extremely low water absorption / water vapor permeability are to be emphasized.

Polychlorotrifluoroethylene (abbreviation PCTFE) is a fully halogenated polymer that belongs to the class of polyhalogenolefins. PCTFE is a homopolymer made up of the chlorotrifluoroethylene monomer. Like other fluoroplastics, PCTFE is very resistant to many chemicals. In addition, PCTFE has the highest hardness, strength and rigidity among fluoroplastics. PCTFE is dimensionally stable, can be machined very well and can be used in a wide temperature range (approx. -240 ° C to +205 ° C). The thermal conductivity of PCTFE is 0.209 W / (K m) and is therefore in the range of the thermal conductivity of the microcellular structure. PCTFE is a transparent high barrier material for blister applications. PCTFE films offer very good barrier properties with regard to water vapor permeability and also good chemical resistance.

According to one embodiment, it is provided that the inner layer and / or the outer layer comprise thermoplastics, in particular polyolefins, thermoplastic elastomers (TPE), in particular thermoplastic olefins, optionally as a copolymer with polyamide, polyester, polystyrene or urethane, and / or polypropylene. Thermoplastics, also called plastomers, are plastics that can be deformed in a certain temperature range (thermoplastic). This process is reversible, that is, it can be repeated as often as required by cooling and reheating to the molten state, as long as the so-called thermal decomposition of the material does not start due to overheating. This distinguishes thermoplastics from thermosets and elastomers. Another unique selling point is the weldability of thermoplastics. Thermoplastics are made up of little or unbranched, i.e. linear, carbon chains that are connected to one another only by weak physical bonds. These binding forces are more effective when the chains are aligned in parallel. Such areas are called crystalline, in contrast to amorphous (disordered) areas in which the macromolecules are convoluted. Thermoplastics were originally primarily processed using the injection molding process, which is why they were also called injection molding compounds (in contrast to thermosets, which were called molding compounds). Today, extrusion is another important processing technique. Other processing options are e.g. B. blow molding, film blowing, hot caulking and calendering.

Polyolefins are polymers that are produced from alkenes such as ethylene, propylene, 1-butene or isobutene by chain polymerization. The polyolefins are saturated hydrocarbons, which make up the largest group of plastics in terms of volume. They are semi-crystalline thermoplastics that are easy to process. They are characterized by good chemical resistance and electrical insulation properties.

Thermoplastic elastomers (abbreviation TPE, sometimes also called elastoplasts) are plastics that behave comparable to classic elastomers at room temperature, but can be plastically deformed when heated and thus show thermoplastic behavior. Thermoplastic elastomers are elastomers that behave like classic representatives of the elastomers at room temperature, but become deformable when heated. A distinction is made between copolymers and elastomer alloys according to the internal structure.

Copolymers are used either as statistical or as block copolymers. The former consist of a crystallizing (and thus physically crosslinking) main polymer such as. B. polyethylene, the degree of crystallization by a randomly installed along the chain comonomer such. B. vinyl acetate is reduced so far that the crystallites (= the hard phase) in the finished material (in the example EVA) no direct contact have more. As in conventional elastomers, they then act as isolated crosslinking points.

In block copolymers, the hard and soft segments are sharply separated in one molecule (e.g. SBS, SIS). With TPEs, the material separates below a certain temperature into a continuous and a discontinuous phase. As soon as the latter falls below its glass transition temperature T _g (the T _{g of} the continuous phase is significantly below the later application temperature), it in turn acts as a crosslinking point.

Elastomer alloys are polyblends, i.e. mixtures of finished polymers, so the plastic consists of several types of molecules. Different mixing ratios and aggregates result in tailor-made materials (e.g. polyolefin elastomer made of polypropylene (PP) and natural rubber (NR) - depending on the ratio, they cover a wide range of hardness).

Thermoplastic polyester elastomers (TPE) form a group of block copolymers with hard crystalline and soft rubber segments. As a result, they have both thermoplastic and elastomeric properties, which are strongly influenced by the relationship between the hard and soft segments and by their type. TPE is used when conditions are severe and, for example, high elasticity in combination with high mechanical strength and durability is required. Examples include shock absorbing parts, flexible connectors and pipes, seals and membranes. Glass fiber reinforced grades are used when higher demands are placed on the forming temperature.

Resistance to heat and chemicals increases with the hardness and rigidity of the TPE. The hardest varieties can withstand 150 ° C for a short time, but for longer periods approx. 80 ° C is the upper limit.

The moisture absorption of TPE depends to a large extent on the chemical structure. A typical value is 1.1% at 23 ° C and 50% relative humidity and 0.5% when saturated in water at 23 ° C. TPE is resistant to mineral oils and fats, to non-aromatic hydrocarbons as well as to dilute acids, bases and alkaline substances. The material is not resistant to hot water and strong acids and bases, alcohol and halogenated and aromatic hydrocarbons. The UV resistance is moderate; UV-stable varieties are required for outdoor use. The main advantage of non-reinforced TPE is the possibility of recovery after deformation, which can be up to 25%. Resistance to cold deformation is limited, while the strength when stretched is much better than that of rubber. The impact resistance is excellent down to - 80 ° C, depending on the chemical structure.

Olefine is a generic term used especially in the petrochemical industry for all acyclic and cyclic hydrocarbons with one or more carbon-carbon double bonds. Aromatic compounds are an exception. All alkenes, cycloalkenes and polyenes are considered to be olefins.

Ethylene-propylene-diene rubbers (EPDM, ethylene-propylene-diene; M group) are terpolymers of ethylene, propylene and an unspecified diene. EPDM is one of the synthetic rubbers with a saturated main chain (according to DIN: M group). Unsaturated main chain rubbers, such as. B. natural rubber or styrene-butadiene rubber, however, belong to the R group. EPDM rubbers have double bonds in the side chains and are therefore also vulcanizable with sulfur.

Low density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene. LDPE is defined by a density range of 0.917-0.930 g / cm ³ . It is not reactive at room temperatures except through strong oxidizing agents and some solvents cause swelling. It can withstand temperatures of 80 ° C and 95 ° C for a short time. Made in translucent or opaque variations, it is quite flexible and tough.

High density polyethylene (PEHD) is a polyethylene thermoplastic made from petroleum. With a high strength-to-density ratio, HDPE is used in the manufacture of plastic bottles, corrosion-resistant pipes, geomembranes and plastic woods. HDPE is known for its large strength-density ratio. The density of HDPE can be between 930 and 970 kg / m ³ .

According to one embodiment, the inner layer has a layer thickness of 0.15 to 0.8 mm, the outer layer has a layer thickness of 0.15 to 0.8 mm and the barrier layer has a layer thickness of 0.05 to 0.25 mm.

The layer thickness of the multilayer wall is thus advantageously carried out so that the rigidity is not too great and by pressing the wall by hand bottle according to the invention a targeted metering of the liquid, solvent-containing composition is possible. Due to the improved thermal insulation effect of the microcellular layer in the inner layer and / or in the outer layer, there is no significant heat transfer from the hand of the user to the liquid, solvent-containing composition. Unwanted boiling over, for example, of a composition containing acetone in the bottle according to the invention is avoided.

According to one embodiment, it is provided that the multilayer wall comprises a first additional layer between the inner layer and the barrier layer and / or comprises an additional second layer between the barrier layer and the outer layer, the first additional layer and / or the second additional layer comprising adhesion promoters.

The thickness of the first and second additional layers is 0.05 to 0.25 mm. The arrangement of the inner layer, barrier layer and outer layer is by no means rigid. Depending on the desired properties of the bottle according to the invention, one or more intermediate layers can be arranged between the inner layer and the barrier layer and between the barrier layer and the outer layer.

According to one embodiment, the thermal conductivity l of the multilayer wall is less than 0.25 W / (m K). The thermal conductivity l of the multilayer wall is particularly preferably less than or equal to 0.15 W / (m K), preferably less than or equal to or less than 0.09 W / (m K), particularly preferably less than or equal to 0.08 W / (m K), in particular 0.08 W / (m K) to 0.02 W / (m K), preferably with respect to the cross section, ie perpendicular to the areal extent, i.e. perpendicular to the side surface of the multilayer wall.

The thermal conductivity l of the multilayer wall is determined by determining the temperature conductivity of the multilayer wall, in particular using an IR detector to determine the time course of the temperature rise of one of the two lateral surfaces of the multilayer wall (specimen top side of a material), for example the upper side of the multilayer wall after a heat pulse on the opposite Surface of the multilayer wall (the underside of the test specimen), for example the underside of the multilayer wall, determined (Netzsch LFA 427, Netsch LFA 467).

The thermal conductivity l of the multi-layer wall is determined by generating a heat pulse on one side surface of the multi-layer wall (underside of the test specimen) and at the same time an IR detector measures the temperature increase on the opposite surface of the multi-layer wall (top of the test specimen). Thermal conductivity l = amount of heat in joules, which in the stationary state is passed through a body of a certain cross-section in a certain time unit, the temperature gradient being 1 K, as W (m K) -1, the thermal conductivity l being determined in accordance with FOURIER's law can (Formula 2).

Compared to non-foamed polymers, the thermal conductivity of the microcellular layer is significantly lower. While HDPE has a thermal conductivity of approximately 0.7 to 0.8 W / (m K), LFPE a thermal conductivity of approximately 0.5 to 0.6 W / (m K) and elastomers a thermal conductivity of approximately 0.09 to 0, 3, the thermal conductivity of polymer foams is from 0.025 to 0.2 W / (m K). The thermal conductivity l for polypropylene is 0.22 W / (m K). Foaming can reduce the value up to 10%. Foaming can reduce the value up to 10%.

The rated value of the thermal conductivity can preferably be determined according to DIN EN ISO 220007. The thermal conductivity is preferably determined using the Hyperflash® measuring method from Netsch Gerätebau.

The thermal conductivity is a material property and represents the heat flow through a material due to the heat conduction. The specific thermal resistance is the reciprocal of the thermal conductivity. The thermal conductivity can be measured with a heat flow meter or heat flow calorimeter. For a given thickness of a sample, the temperature difference can be determined, for example, with a Peltier element on a defined measuring surface. Alternatively, measurement with heat flow sensors, which determine the heat flows based on the Seebeck effect, is possible. The heat flow and the absolute temperature are determined. The thermal conductivity of a substance can be determined using heat conduction or Fourier's law. Measuring device, for example "Heat Flow Meter 6891/000" from Ceast, corresponds to the schematic structure of a stationary test system.

The temperature conductivity of the sample is determined according to the HyperFlash method to be used to determine the thermal conductivity. The thermal conductivity can be calculated via the temperature-dependent density and the specific heat capacity of a plastic, here also the multi-layer wall, inner layer, barrier layer and or outer layer. According to the invention, the thermal conductivity is calculated via the temperature-dependent density and the specific heat capacity of the multilayer wall comprising at least one inner layer, at least one barrier layer and at least one outer layer. The measurement can be carried out without contact in a temperature range between -100 to 500 ° C, in particular in the temperature range from -10 to 100 ° C, by a xenon lamp the underside of the sample, here a surface of the two sides, in particular one of the two side surfaces , the multilayer wall, heated. An IR detector measures the temperature rise on the opposite surface of the two sides, in particular the opposite side surface of the multilayer wall. This method therefore determines the temperature conductivity depending on the direction. The measuring range can be between 0.1 and 2,000 W / (mK). The sample used, here the multilayer wall, in particular the wall thickness of the multilayer wall, should be between 0.01 and 6 mm thick. Round or polygonal samples should have a diameter or side length greater than 6 mm and less than 25.4 mm.

The measurement using an IR detector, which is based on the time course of the temperature rise on the upper side of a material (here: one of two opposite surfaces of the multi-layer wall, e.g. upper side) after a heat pulse on the underside of the sample (here: the opposite surface of the multi-layer wall, e.g. bottom) determined (Netzsch LFA 427, Netsch LFA 467). A heat pulse is generated on the underside of the test specimen and at the same time an IR detector on the top of the test specimen measures the temperature rise. The temperature conductivity can be determined from the change in temperature over time. The thermal conductivity results from the context (taking into account all three spatial directions, the complete thermal conductivity equation results:

= Temperature control number (formula l)

The thermal conductivity or coefficient of thermal conductivity l corresponds to the amount of heat in joules which, in the stationary state, is passed through a body of a certain cross-section in a certain time unit, the temperature gradient being 1 K. The physical unit of this size is W (m K) ¹ (watts per meter and Kelvin). The basic empirical equation (FOURIER's law) for all heat conduction processes is:

Q IT

l r

i Sx

(Formula 2)

Q amount of heat

t time l thermal conductivity

T temperature

x length in heat transport direction and

A ₀ Cross section of the test object

According to one embodiment, it is provided that the multilayer wall is the product of an extrusion blow molding, in particular a coextrusion blow molding.

As a result, the multilayer wall according to the invention can take any shape. Extrusion blow molding, also called blow molding, is a process in plastics processing for the production of hollow bodies from thermoplastic materials. The melted polymer is pressed through the nozzle via a screw conveyor, so that a tubular preform is formed (extrusion). This is transferred into a blow mold and adapted to the internal contours of the mold by internal pressure (blow molding).

According to one embodiment, the total layer thickness of the multilayer wall is 0.5 to 1.2 mm.

The multilayer wall is thus suitable for the production of bottles or tubes for the dental application for storing and / or applying a liquid composition containing solvents.

The invention further relates to a method for producing a multilayer wall, the method comprising the method steps:

1) ^a )

- Providing granules or a mixture of granules to form an inner layer and / or outer layer of a multi-layer wall with a microcellular structure;

- Forming an extrudate to form an inner layer and / or outer layer of a multi-layer wall with a microcellular structure;

- Mixing at least one extrudate to form an inner layer and / or outer layer of a multilayer wall with a microcellular structure with inert gas and / or carbon dioxide, and obtaining an extrudate comprising inert gas and / or carbon dioxide, and

b)

Providing granules of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), - Forming an extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), optionally steps a) and b) can be carried out simultaneously, and c) co-extrusion blow molding of a tube with a multi-layer wall with the layer structure from the inside to the outside: inner layer , Barrier layer, outer layer, in a blowing tool or inserting the hose in a blowing tool, followed by the steps

d) optionally clamping or disconnecting the hose with a multi-layer wall, e) inflating the hose provided in the blowing tool with a multi-layer wall, in particular the multi-layer wall

(i) an outer layer

a) from the extrudate comprising inert gas and / or carbon dioxide

Formation of an outer layer of a multilayer wall with a microcellular structure, or

b) from an extrudate, in particular a thermoplastic elastomer,

(ii) a barrier layer made from the extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), and

(iii) an inner layer

a) from the extrudate comprising inert gas and / or carbon dioxide

b) from an extrudate, in particular a thermoplastic elastomer, the multilayer wall comprising an inner layer, barrier layer and an outer layer from the inside out, at least one inner or outer layer or inner and outer layer having a microcellular structure, and f) obtaining a multilayer wall , or

) a) (i) extrusion blow molding an outer layer of the multilayer wall ,, a) from the

Extrudate to form an outer layer of a multilayer wall with a microcellular structure, or b) from an extrudate, preferably from a thermoplastic elastomer to form an inner layer of a multilayer wall,

(11.1) providing an extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC),

(11.2) extrusion blow molding a barrier layer from the extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), and

(iii) extrusion blow molding an inner layer of the multilayer wall, from a) the extrudate comprising inert gas and / or carbon dioxide to form an inner layer of a multilayer wall with a microcellular structure, or b) from an extrudate, preferably of a thermoplastic elastomer for forming an inner layer of a multilayer wall, and obtaining a multilayer wall.

The invention also relates to a multilayer wall obtainable by the process and a container or a hollow body obtainable by the process. The invention further relates to a container or hollow body, in particular a thermally insulated container or thermally insulated hollow body, comprising bottles, tubes, single-dose vials, bags, sachets, cans without a lid or cans with a lid and / or syringe bodies comprising the multilayer wall as integral part of the container or the hollow body. The invention also relates to a container or hollow body consisting of the multilayer wall.

It is a multi-layer extrusion blow molding with modified extrudates for each layer. The layers from different extrudates are co-extruded simultaneously as a multi-layer wall.

According to one embodiment, the provision of a microcellular structure as the inner layer and / or outer layer comprises the method steps:

- Mixing a first granulate and a second granulate in an injection molding machine to produce a polymer;

Melting the polymer in the injection molding machine;

- adding a supercritical fluid to the injection molding machine; and

Dissolving the supercritical fluid in the polymer; or

- physical and / or chemical introduction of a blowing agent, or

- Injecting carbon dioxide gas and / or nitrogen gas;

- Forming fluid bubbles in the polymer;

Optionally, a supercritical fluid and a blowing agent and / or a gas can be used in combination in the process.

The invention relates to the use of a multi-layer wall for a container for storing and optionally applying a liquid or pasty composition, preferably a solvent-containing composition, particularly preferably a dental liquid or a dental gel, in particular a dental adhesive, dental bonds, dentin adhesion promoter, dental primer or dental etchant. According to a preferred embodiment it is provided that the container comprises a bottle, a tube, single-dose vial, pouch, sachet, can with a lid and / or syringe body.

According to a further embodiment, the use of the multilayer wall comprises the formation of the multilayer wall as an integral component of a container or hollow body for the storage and / or transport of compositions, in particular solvent-containing compositions, including paint, lacquers, adhesives, foods and / or cosmetics.

Further details, features and advantages of the invention result from the drawings, as well as from the following description of preferred embodiments with reference to the drawings. The drawings illustrate only exemplary embodiments of the invention, which do not restrict the essential inventive concept.

Figure description

1 shows the multilayer wall according to the invention in an enlargement, the inner layer having the microcellular structure.

2 shows the multilayer wall according to the invention in an enlargement, the outer layer having the microcellular structure.

3 shows the multilayer wall according to the invention in an enlargement, the inner layer and the outer layer having the microcellular structure.

4 shows an enlargement of the microcellular structure.

Embodiments of the invention

1 shows the multilayer wall 20 of a bottle 30 according to the invention in an enlargement, the inner layer 21 having the microcellular structure. The bottle 30 has a multilayer wall 20 in at least one area, the multilayer wall 20 comprising an inner layer 21, a barrier layer 22 and an outer layer 23. In Fig. 1, the inner layer has the microcellular structure 24, which is characterized by embedded fluid bubbles 25. The fluid bubbles 25 are created by a physically or chemically introduced blowing agent in a polymer and form a polymer foam. The blowing agent is an inert gas, in particular nitrogen, gaseous carbon dioxide and / or a mixture of at least two of the gases mentioned. The inner layer 21 and / or the outer layer 23 comprises thermoplastics, in particular polyolefins, thermoplastic elastomers (TPE), in particular thermoplastic olefins, optionally as a copolymer with polyamide, polyester, polystyrene or urethane and / or polypropylene.

The barrier layer 22 comprises an ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC) optionally laminated with polychlorotrifluoroethylene (PCTFE). The barrier layer 22 is designed to form a barrier for oxygen and / or water vapor. In one embodiment, the multi-layer wall 20 is the product of a multi-layer coextrusion blow molding with modified extrudates for the respective layer.

2 shows the multi-layer wall 20 according to the invention of a bottle 30 in one

Enlargement, wherein the outer layer 23 has the microcellular structure.

In one embodiment, the multilayer wall 20 can also comprise additional layers. For example, in one embodiment, at least one additional layer can be arranged between the inner layer 21 and the barrier layer 22 and / or between the barrier layer 22 and the outer layer 23. Depending on the material from which this additional layer consists, the multilayer wall 20 can be given additional properties.

3 shows the multi-layer wall 20 according to the invention of a bottle 30 in one

Enlargement, wherein the inner layer 21 and the outer layer 23 have the microcellular structure. Since the microcellular structure has a very low thermal conductivity coefficient 1, the thermal conductivity of the multilayer wall 20 of the bottle 30 is lowest in this configuration of the layers in comparison with the previous arrangements. The thermal conductivity coefficient l is approx. 0.025 to 0.2 W / (m K). Boiling over of acetone-containing compositions in bottle 30 is thus avoided during application, since hardly any heat is transferred from the user's hand to the acetone-containing composition in the bottle.

FIG. 4 shows an enlargement of the microcellular structure 24 with the fluid bubbles 25. The size of the fluid bubbles 25 depends on the amount of the blowing agent introduced and the material used. In preferred embodiments, a microcellular material according to the invention is produced which has an average cell size of less than about 60 pm or 50 pm. In some embodiments, a particularly small cell size is desired and in these embodiments the material according to the invention has an average cell size of less than about 30 pm, more preferably than about 20 pm, and particularly preferably less than about 10 pm, and most preferably less than about 5 pm. The microcellular material preferably has a maximum cell size of about 100 pm or preferably less than about 75 pm. In embodiments in which a particularly small cell size is desired, the material can have a maximum cell size of approximately 50 pm, particularly preferably approximately 35 pm and very particularly preferably approximately 25 pm. A number of embodiments include all combinations of these labeled average cell sizes and maximum cell sizes. For example, one embodiment in this series of embodiments includes a microcellular material that has an average cell size of less than about 30 pm with a maximum cell size of about 40 pm, and as another example, an average cell size of less than about 30 pm with one maximum cell size of about 35 pm. This means that a microcellular material which is designed for a multitude of purposes can be produced with a special combination of average cell size and maximum cell size, preferably for this purpose.

Reference symbol list

20 multi-layer wall

21 inner layer

22 barrier layer

23 outer layer

24 microcellular structure

25 fluid bubbles

30 containers, bottle

Claims

1. multilayer wall, characterized in that the multilayer wall (20) comprises at least one inner layer (21), a barrier layer (22) and an outer layer (23), the barrier layer (22) being designed to be a barrier to oxygen and / or To form water vapor, wherein the inner layer (21) and / or the outer layer (23) has a microcellular structure (24), wherein the microcellular structure (24) has fluid bubbles (25), and wherein the fluid bubbles (25) product of a physical and / or chemically introduced propellant, characterized in that the thermal conductivity l of the multilayer wall (20) is less than 0.25 W / (m K).

2. Multi-layer wall according to claim 1, characterized in that the blowing agent in the microcellular structure (24) comprises inert gas, in particular nitrogen, gaseous carbon dioxide and / or a mixture of at least two of the gases mentioned.

3. Multi-layer wall according to claim 2, characterized in that the microcellular structure (24) has a void volume of less than 60% to greater than or equal to 10%.

4. Multi-layer wall according to one of claims 1 to 3, characterized in that the diameter of the fluid bubbles (25) is less than or equal to 300 pm, in particular less than or equal to 200 pm, preferably less than or equal to 100 pm, particularly preferably less than or equal to 50 pm.

5. Multi-layer wall according to one of claims 1 to 4, characterized in that the barrier layer (22) comprises an ethylene-vinyl alcohol copolymer (EVOH) or cycloolefin copolymer (COC) optionally laminated with polychlorotrifluoroethylene (PCTFE).

6. Multi-layer wall according to one of claims 1 to 5, characterized in that the inner layer (21) and / or the outer layer (23) thermoplastics, in particular polyolefins, thermoplastic elastomers (TPE), in particular thermoplastic olefins optionally as copolymers with polyamide, Polyester, polystyrene or urethane, and / or polypropylene.

7. Multi-layer wall according to one of claims 1 to 6, characterized in that the inner layer (21) has a layer thickness of 0.15 to 0.8 mm, the outer layer (23) a layer thickness of 0.15 to 0.8 mm and the barrier layer (22) has a layer thickness of 0.05 to 0.25 mm.

8. Multi-layer wall according to one of claims 1 to 7, characterized in that the multi-layer wall (20) between the inner layer (21) and the barrier layer (22) comprises a first additional layer (26) and / or between the barrier layer (22) and the outer layer (23) comprises an additional second layer (27), the first additional layer (26) and / or the second additional layer (27) comprising adhesion promoters.

9. multilayer wall according to one of claims 1 to 8, characterized in that the thermal conductivity l of the multilayer wall is determined by generating a heat pulse on a lateral surface of the multilayer wall (underside of the test specimen) and at the same time an IR detector on the opposite surface of the multilayer wall ( Top of the test specimen) measures the temperature rise.

10. Multi-layer wall according to one of claims 1 to 9, characterized in that the multi-layer wall is the product of an extrusion blow molding, in particular coextrusion blow molding.

11. Multi-layer wall according to one of claims 1 to 10, characterized in that the total layer thickness of the multi-layer wall (20) is 0.5 to 1, 2 mm.

12. A method for producing a multilayer wall, characterized in that the method comprises the method steps:

1) ^a )

- Providing granules or a mixture of granules to form an inner layer (21) and / or an outer layer (23) of a multilayer wall (20) with a microcellular structure (24);

- Forming an extrudate to form an inner layer (21) and / or outer layer (23) of a multilayer wall (20) with a microcellular structure (24);

- Mixing at least one extrudate to form an inner layer (21) and / or outer layer (23) of a multilayer wall (20) with a microcellular structure (24) with inert gas and / or carbon dioxide, and obtaining an extrudate comprising inert gas and / or carbon dioxide, and

b)

Providing granules of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC),

- Forming an extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), optionally steps a) and b) can be carried out simultaneously, and c) Co-extrusion blow molding of a hose with a multi-layer wall (20) with the layer structure from the inside to the outside: inner layer, barrier layer, outer layer, in a blowing tool or inserting the hose into a blowing tool, followed by the steps

(i) an outer layer (23)

a) from the extrudate comprising inert gas and / or carbon dioxide to form an outer layer (23) of a multilayer wall (20) with a microcellular structure (24), or

b) from an extrudate, in particular a thermoplastic elastomer,

(ii) a barrier layer (22) made from the extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), and

(iii) an inner layer (21)

b) an extrudate, in particular a thermoplastic elastomer, the multilayer wall comprising an inner layer, barrier layer and an outer layer from the inside out, at least one inner or outer layer or inner and outer layer having a microcellular structure (24), and f) Obtaining a multi-layer wall (20), or

2) a) (i) extrusion blow molding an outer layer (23) of the multilayer wall ,, a) from the extrudate to form an outer layer (23) of a multilayer wall (20) with a microcellular structure (24), or b) from an extrudate, preferably from a thermoplastic elastomer to form an inner layer (21)

Multi-layer wall (20),

(11.2) extrusion blow molding a barrier layer (22) from the extrudate of ethylene-vinyl alcohol copolymer or cycloolefin copolymer (COC), and

(iii) extrusion blow molding an inner layer (21) of the multilayer wall, from a) the extrudate comprising inert gas and / or carbon dioxide to form an inner layer (21) of a multilayer wall (20) with a microcellular structure (24), or b) from an extrudate, preferably made of a thermoplastic elastomer for forming an inner layer (21) of a multilayer wall (20), and obtaining a multi-layer wall (20).

13. Use of a multilayer wall according to one of claims 1 to 11 or obtainable according to claim 12 as part of a container (30) for storing and optionally applying a liquid or pasty composition, preferably a solvent-containing composition, particularly preferably a dental liquid or a dental gel, in particular a dental adhesive, dental bonding, dentine adhesion promoter, dental primer or dental etchant.

14. Use of the multi-layer wall according to claim 13, characterized in that the container (30) comprises a bottle, a tube, single-dose vial, bag, sachet can with a lid and / or syringe body.

15. Use of the multilayer wall according to one of claims 1 to 11 or obtainable according to claim 12 as an integral part of a container or hollow body for the storage and / or transport of compositions, in particular solvent-containing compositions, include paint, varnish, adhesives, food and / or cosmetics.