Mash filter membrane

Abstract

To provide a mash filter membrane for use in the filtration of mash, in the field of brewing beverages like beer.SOLUTION: The invention is directed to a mash filter membrane comprising an elastomeric composition that comprises more than 50 wt.% of one or more elastomer, based on the total weight of polymers in the elastomeric composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention is in the field of brewing beverages such as beer, and in particular relates to a mash filter membrane for use in the filtration of mash. [Background technology]

[0002] Mashing is the process step in brewing where milled grains are usually heated together with water to produce and extract sugars and other components from the grains, producing a mash, a suspension of wort and spent grains as solids. To proceed further in the brewing process, the wort must be separated from the spent grains in the mash by a mash filtering or lautering process. In large breweries, this is usually done using a mash filtering unit such as that marketed by Meura SA of Belgium described in EP0674929. Other similar types of mash filtering units are also marketed by Landaluce SA of Spain and Lehui of China.

[0003] An example of mash filtration is described in US5453285. Typically, in such a process, the mash is introduced into a chamber between a filter (commonly a fabric filter) and a membrane (sometimes called a bladder) in a mash filtration unit. The membrane is used to apply pressure to the mash to force the wort from the mash through the filter. The residual spent grain bed, sandwiched between the filter and the membrane, can be rinsed with hot water if necessary to further extract any remaining sugars in the residual spent grain bed. Once filtration is complete, the chamber is opened and the spent grain bed is removed, and the cycle can be repeated with the next brew or the next batch of mash.

[0004] As described in EP0674929, the mash filter membrane has a degree of elasticity and can contract when the mash is introduced into the chamber and expand to apply further pressure to the mash (e.g. up to about 1200 mbar).

[0005] Conventional mash filter membranes, such as those marketed by Meura SA, have several drawbacks. After a certain number of brews, the membrane breaks or tears, losing its structural integrity and must be replaced. This replacement requires downtime of the filtration unit. To make matters worse, the frequency of membrane breakage is relatively difficult to predict, meaning that one membrane of a certain type may last longer than another membrane of the same type. This means that there is variability in the rubber composition of each membrane. This unpredictable durability of conventional membranes makes it difficult to plan maintenance, leading to even more downtime. Conventional mash filter membranes are also prone to tearing and breaking, as well as to the formation of folds and wrinkles over time. The folds not only affect the structural integrity of the membrane, but also prevent the spent grain bed from being trapped and retained in the folds, preventing the discharge of the spent grain bed from the open chamber. This requires manual assistance to discharge the spent grain bed, which is undesirable for efficiency and safety. Another drawback of conventional mash filter membranes is their stickiness, especially during the first two brews after cleaning in place (CIP) has been performed.

[0006] DE 4313103 discloses a membrane filter system and an elastomeric membrane sheet. However, as is more common in the art, the sheet is believed to be elastomeric, even though parts of the sheet are expressly stated to be non-elastomeric. It is also known that conventional membranes, even if they have elastomeric properties, may contain less than 50% elastomer.

[0007] EP0142173 discloses a diaphragm for a filter press. It is said that the diaphragm exhibits good heat and heat aging or chemical resistance compared to other rubber diaphragms. However, there is no information on its suitability for mash filtration, much less its advantages, which are not apparent from EP0142173.

[0008] It is an object of the present invention to provide an improved mash filter membrane that does not suffer from one or more of the above-mentioned disadvantages associated with conventional membranes, and in particular to provide a mash filter membrane that is more durable and requires no or less frequent replacement than conventional membranes. Summary of the Invention

[0009] The inventors have surprisingly found that this objective is achieved by providing a mash filter membrane that retains its elasticity over multiple brews. To achieve the above objective, the present invention provides a mash filter membrane having an elastomeric composition having greater than 50 weight percent (wt%) of one or more elastomers, based on the total amount of polymers in the elastomeric composition.

[0010] The term elastomer herein means a polymer having elastic properties and includes natural and synthetic elastomers, also known as rubbers. The elastomers of the present invention preferably comprise synthetic elastomers due to better control over their properties.

[0011] Some conventional mash filter membranes include elastomeric compositions based on the elastic copolymer ethylene propylene diene monomer (EPDM) and a non-elastic thermoplastic polymer (also called the plastic or thermoplastic phase), such as polyethylene (PE) or polypropylene (PP). For example, the composition of the mash filter membrane offered by Meura SA in Belgium consists of 50% EPDM and 50% PE. Since the elastic properties of the membrane are mainly contributed by EPDM, conventional membranes are sometimes called EPDM membranes even if they contain plastics such as PE. Due to the presence of plastics in conventional compositions, the compositions can be considered as plastics and it is easy to obtain a food grade rating according to regulations set by the relevant authorities (e.g., the U.S. Food and Drug Administration FDA, the Netherlands Food and Consumer Product Safety Authority NVWA). For example, conventional plastic-containing elastomeric compositions may comply with EU Regulation (EU) 10 / 2011 and / or EU Regulation (EU) 282 / 2008. Without wishing to be bound by theory, the inventors believe that the presence of plastic in the elastomeric composition adversely affects the durability of the membrane.

[0012] The elastomeric composition preferably contains as little plastic as possible. Although beneficial effects may already be observed below 50% by weight of plastic, elastomeric compositions containing more than 60% in particular show improved durability. Improved durability can be observed with increasing amounts of elastomer in the composition. Thus, the composition based on the total weight of the polymers in the elastomeric composition preferably contains more than 80% by weight of said elastomer, more preferably more than 90% by weight, even more preferably more than 95% by weight, and most preferably nearly 100% by weight. That is, the elastomeric composition is most preferably essentially free of plastic.

[0013] The limited or no use of plastics in the elastomeric composition may alternatively or additionally be expressed as the elastomeric composition comprising less than 50% of one or more non-elastomeric polymers, such as non-elastomeric thermoplastic polymers, preferably less than 25%, more preferably less than 10%, based on the total weight of the polymers in the elastomeric composition. The non-elastomeric polymers are typically polyolefin homopolymers, such as one or more polymers selected from the group of polyethylene, polypropylene, polystyrene, etc.

[0014] The elastomer composition preferably has sufficient resistance to an alkaline solution (e.g., 2% alkaline solution) that can be used for CIP. For this reason, the elastomer preferably contains EPDM. Other suitable elastomers include one or more selected from the group consisting of EPDM, FKM (e.g., Viton (trademark) conforming to ASTM D1418 standard), FFKM (e.g., Kalrez (trademark) conforming to ASTM D1418 standard), and nitrile butadiene rubber (NBR).

[0015] In a particular embodiment, the elastomer preferably comprises a copolymer, such as a block copolymer, such as polystyrene-block-polybutadiene-block-polystyrene (SBS) or polystyrene-block-polyisobutene-block-polystyrene (SIS), which are triblock copolymers. In another particular embodiment, the elastomer comprises an olefin elastomer, such as ethylene propylene rubber (EPR), nitrile butadiene rubber (NBR), EPDM, polystyrene-copolybutadiene rubber (SBR), and the like.

[0016] It is understood that the elastomer composition may optionally contain additives such as fillers, such as carbon black, curing agents, stabilizers, plasticizers, etc. The elastomer composition of the present invention is preferably cured or crosslinked by peroxide. Conventional elastomer compositions for membranes have been cured or crosslinked by sulfur, but it has been found that curing or crosslinking by peroxide provides a more durable membrane. In other words, crosslinking or curing by sulfur is less preferred.

[0017] In certain embodiments, the membrane consists essentially entirely of the elastomeric composition. In other embodiments, the membrane may have a layer or patch of the composition and another composition, such as a perfluorinated compound (PFC) composition, disposed on the side of the membrane that is intended to contact the mash. An advantage of perfluorinated compounds is their inertness, which may further enhance the durability of the membrane.

[0018] The elastomeric composition of the present invention is preferably food grade. Surprisingly, this can be achieved even with an elastomeric composition that essentially consists of EPDM. The inventors have therefore found that in order to comply with regulations, it is not necessary for the composition to contain at least 50% plastic, as is the case with conventional elastomeric compositions. The elastomeric composition of the present invention can comply with EU Directive 95 / 2001 / EC on general product safety, Regulation (EC) N. 1935 / 2004 on materials and articles intended to come into contact with food, the Dutch Food and Consumer Goods Act (including but not limited to Acts and Regulations (Warenwetbesluit en-regeling verpakkingen en gebruiksartikelen) on packaging and consumer goods), Article 33 of EU Regulation (EC) 1907 / 2006, which states that substances of very high concern as defined in the REACH Act should not be present above 0.1 wt%, and / or Food and Drug Administration (FDA) CFR Title 21 - Part 177 - Indirect food additives: rubber products intended for repeated use of polymers § 177.2600. This means that the elastomeric composition preferably consists only of such compositions that remain below the total migration limits set out in Regulation (EC) N. 1935 / 2004. This testing can be carried out in accordance with relevant legislation, for example, US Code of Federal Regulations Title 21, which lays down the basic rules required for testing the migration of components of plastic materials and articles intended for contact with food, EU Directive 82 / 711 / EEC, EU Directive 93 / 8 / EEC, EU Directive 97 / 48 / EC, and / or EU Directive 85 / 572 / EEC, which lays down the list of simulants to be used for migration testing. Suitable compositions and additives for the elastomeric composition are also listed in the so-called "white lists" associated with these regulations. The elastomeric composition of the present invention preferably also meets the requirements laid down in Regulation (EC) N. 2023 / 2006 Good Manufacturing Practice.

[0019] A further aspect of the present invention is a method for producing a membrane. Conventionally, membranes are generally produced by compression molding. A drawback of this method is the limited control of process parameters. For example, pellets of starting materials such as raw EPDM and raw PE may be biased, resulting in a non-uniform final composition. The inventors have found that the inconsistent durability of conventional membranes may be due to insufficient process control in compression molding. Therefore, the membrane of the present invention is preferably produced by a molding process including mixing of the melt of the composition, such as injection molding. It has been found that injection molding results in a narrower variation in the durability of the membrane. That is, the membrane of the present invention is preferably obtained by a molding process such as injection molding including mixing of the melt of the composition. This method is suitable for the production of a membrane of typically 1 m according to the present invention. 2 More than 2 m, preferably 2 More than 3 m, preferably 2 More than 3.5 m, preferably 2 More than 3.6 m, most preferably about 3.6 m 2 It has also been found that the present invention is particularly suitable for producing membranes having a relatively large size, such as a membrane having a one-sided surface area of ​​100 nm or more.

[0020] It has been found that particularly preferred durable membranes have an elastomeric composition which, prior to use of the membrane, preferably has one or more, and more preferably all, of the following material properties: The tensile strength as specified by ISO37:2011, Type 2 is greater than 5 MPa, preferably greater than 8 MPa, more preferably greater than 10 MPa, for example about 12 MPa. The M300 deformation modulus as specified by ISO37:2011, Type 2 is greater than 4 MPa, preferably greater than 4.5 MPa, more preferably greater than 5 MPa, for example about 8.6 MPa. The elongation at break as specified by ISO37:2011, Type 2 is greater than 200%, preferably greater than 300%, more preferably greater than 400%, for example 421%. Density specified by UNI EN ISO1183-1 is 1 g / cm 3 exceeding 1.06 g / m 3 It is. The Shore A hardness as specified by UNI ISO 7619-1 is in the range of 60 to 75 ShA, preferably in the range of 65-71 ShA, for example 66 ShA.

[0021] Each of the above material properties contributes to the elastomeric composition having favorable properties. It has been found that the change in material properties over time, i.e. with use, can be indicative of the durability of the membrane. It is therefore preferred that the elastomeric composition is constructed such that the change in material properties with use is as small as possible. This has been found to be particularly true for the material property compression set, determined after 72 hours at 70° C. according to ISO 815-1:2014, method A, test piece B. In fact, it is believed that compression set can be used in particular as a reliable parameter for determining the durability of an elastomeric composition. In general, compression set is indicative of the elasticity of the composition. Although the initial compression set (i.e. about 40%) of conventional membranes, for example available from Meura SA, Belgium, is sufficient for an effective mash filtration process, it has been found that a typical conventional membrane increases in compression set (e.g. about 59% after 4700 brews) when used in such a process. On the other hand, the compression set of the membrane according to the invention remains substantially constant for 4700 brews. To this end, the mash filter membrane of the present invention preferably has a compression set of less than 35%, more preferably less than 25%, before use and / or a compression set of less than 50%, more preferably less than 25%, most preferably less than 20% after 4700 brews of about 2 hours each using the membrane or after 90 weeks of use.

[0022] A further aspect of the invention relates to the use of a mash filter membrane or a mash filtration unit in filtering a mash. In other words, in a particular aspect, the invention relates to a method comprising filtering a mash using a mash filter membrane or a mash filtration unit comprising said mash filter membrane. More specifically, said method comprises applying pressure to the mash with the membrane such that wort is forced out of the mash and through the filter.

[0023] The invention can be illustrated by the following examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Example 1 Preparation of membrane Mash filter membranes with a black peroxide cured elastomeric composition containing 100% EPDM (based on the total weight of the polymers in the composition) are made in a mold by injection molding. The size of the membrane is 2 x 1.8 m. 2 and the material properties are shown in Table 1. [Table 1]

[0025] Comparative Example 1: Analysis of conventional membranes A 2×1.8 m2 PTFE-based EPDM / PE composite made by Meura SA of Belgium. 2 The mash filter membrane was analyzed prior to use and had the following material properties, as shown in Table 2. [Table 2]

[0026] Example 2 Evaluation of membrane adhesion One mash filtration unit marketed by Meura SA was fitted with 138 mash filter membranes prepared in Example 1. Another mash filtration unit of the same model was fitted with 138 conventional mash filter membranes as shown in Comparative Example 1. Both mash filtration units, located in the same room, were fed with the same brew (mash) and treated in the same way so that the brewing processes ran in parallel (see below for maintenance intervals).

[0027] The adhesion of the membrane was analyzed taking into account the manual assistance required to remove the spent grain bed from the membrane after daily or monthly CIP. The results are shown in Table 3. [Table 3]

[0028] The results in Table 3 show that the membrane of the present invention is less sticky throughout operating conditions than the conventional membrane.

[0029] Example 3 Evaluation of membrane durability In Example 2, the filtration unit was used for filtering for approximately 90 weeks, performing 4700 brews to filter mash. During this time, the failure rate of the conventional mash filter membrane described in Comparative Example 1 was 13% (18 out of 138), while the failure rate of the mash filter membrane of the present invention in Example 1 was 0% (0 out of 138). Additionally, none of the membranes of the present invention exhibited folds, while significant folds were observed in the conventional filters.

[0030] After 4700 brews of approximately 2 hours duration over a 90 week period, samples of both types of mash filter membranes were analyzed for membrane properties as shown in Table 4 using methods similar to those shown in Tables 1 and 2. [Table 4]

[0031] From Table 2, comparing the conventional membrane with the membrane of the present invention, the membrane of the present invention has a significantly higher strength, which remains almost constant over time, while the conventional membrane loses some of its already low strength and stiffness from the beginning. The tear strength of the membrane of the present invention is higher from the beginning, even after 4700 brews, and the permanent deformation (compression set) of the tested membrane is significantly smaller, which is desirable since in this type of application it is preferable to have as small a compression set as possible.

Claims

1. A mash filter membrane comprising an elastomeric composition containing greater than 95 weight percent of one or more elastomers, based on the total weight of the polymers in the elastomeric composition.

2. A mash filter membrane as described in claim 1, wherein the elastomer composition comprises 100% by weight of the elastomer based on the total weight of the polymers in the elastomer composition.

3. A mash filter membrane as described in claim 1 or 2, wherein the elastomer comprises one or more block copolymers selected from the group consisting of triblock copolymers, polystyrene-block-polybutadiene-block-polystyrene (SBS) and polystyrene-block-polyisobutene-block-polystyrene (SIS), or the elastomer comprises one or more elastomers selected from the group consisting of ethylene propylene rubber (EPR), nitrile butadiene rubber (NBR), EPDM and polystyrene-co-polybutadiene rubber (SBR), or the elastomer comprises one or more elastomers selected from the group consisting of FKM (compliant with ASTM D1418 standard, e.g., Viton™), FFKM (compliant with ASTM D1418 standard, e.g., Kalrez™) and NBR.

4. A mash filter membrane as described in any one of claims 1 to 3, having a compression set of less than 35% determined after 72 hours at 70°C in accordance with ISO815-1:2014, Method A, Test Piece B, the compression set being determined before use of the membrane.

5. A mash filter membrane as described in any one of claims 1 to 4, having a compression set of less than 50% determined after 72 hours at 70°C according to ISO815-1:2014, Method A, Test Piece B, the compression set being determined after 4700 brews using the membrane or after 90 weeks.

6. The mash filter membrane of any one of claims 1 to 5, wherein the elastomer composition, prior to use of the membrane, has one or more of the following material properties: - Tensile strength specified by ISO37:2011, Type 2 exceeds 12 MPa. - M300 deformation modulus as specified by ISO37:2011, Type2 is greater than 5 MPa. - Elongation at break as specified by ISO37:2011, Type 2 is greater than 400%. - Density specified by UNI EN ISO1183-1 is 1g / cm 3 Exceeds. - Shore A hardness as specified by UNI ISO 7619-1 is in the range of 65 to 75ShA.

7. One-sided surface area is 1 m 2 7. The mash filter membrane of claim 1, wherein the membrane is greater than 1000 rpm.

8. A mash filter membrane described in any one of claims 1 to 7, wherein the elastomer composition is cured or crosslinked by peroxide.

9. A mash filtration unit comprising a mash filter membrane according to any one of claims 1 to 8.

10. 10. Use of a mash filter membrane or said mash filtration unit according to any one of claims 1 to 9 in the filtration of a mash.

11. 9. A method for producing a mash filter membrane according to any one of claims 1 to 8, said method comprising mixing a melt of said elastomeric composition.

12. A method for producing a mash filter membrane described in any one of claims 1 to 8, the method comprising the steps of mixing a melt of the elastomer composition and injection molding the elastomer composition.

13. A method for filtering mash, comprising filtering the mash using a mash filtration unit comprising a mash filter membrane described in any one of claims 1 to 8, or a membrane described in claim 10.