SIST EN 14932:2007

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Plastics - Stretch thermoplastic films for wrapping bales - Requirements and test methodsPolimerni materiali - Raztegljive plastomerne folije za zavijanje v bale - Zahteve in preskusne metodePlastiques - Films thermoplastiques étirables pour l' enrubannage de balles - Exigences et méthodes d'essaiKunststoffe - Thermoplastische Stretchfolien zum Umwickeln von Ballen - Anforderungen und PrüfverfahrenTa slovenski standard je istoveten z:EN 14932:2006SIST EN 14932:2007en;fr;de83.140.10Filmi in folijeFilms and sheets55.040SDNLUDQMHPackaging materials and accessoriesICS:SLOVENSKI
STANDARDSIST EN 14932:200701-april-2007







EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14932December 2006ICS 55.040; 83.140.10 English VersionPlastics - Stretch thermoplastic films for wrapping bales -Requirements and test methodsPlastiques - Films thermoplastiques étirables pour l'enrubannage de balles - Exigences et méthodes d'essaiKunststoffe - Thermoplastische Stretchfolien zumUmwickeln von Ballen - Anforderungen und PrüfverfahrenThis European Standard was approved by CEN on 9 November 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14932:2006: E



EN 14932:2006 (E) 2 Contents Page 1 Scope.6 2 Normative references.6 3 Terms and definitions.7 4 Materials.7 5 Solar reflectance.8 6 Durability.8 7 Airtightness and oxygen permeability on bale.8 8 Requirements.9 8.1 General requirements.9 8.2 Requirement for appearance.10 9 Test methods.10 9.1 Determination of thickness.10 9.2 Determination of width.10 9.3 Determination of core protrusion.10 9.4 Determination of length of film.10 9.5 Determination of neck-in.11 9.6 Determination of tensile characteristics.11 9.7 Determination of impact resistance.11 9.8 Determination of slow perforation characteristics.11 9.9 Determination of the tightening force of films.12 9.10 Determination of tear resistance characteristics.12 9.11 Determination of adhesion.12 9.12 Determination of total light transmission.12 9.13 Determination of resistance to artificial weathering.12 9.13.1 Principle.12 9.13.2 Apparatus.12 9.13.3 Test conditions.12 9.13.4 Sampling.13 9.13.5 Test procedure.13 9.13.6 Results.13 9.14 Determination of oxygen permeability.13 10 Determination of leaktightness on the bale.13 11 Designation.13 12 Marking.14



EN 14932:2006 (E) 3 Annex A (normative)
Determination of solar reflectance.15 A.1 Introduction.15 A.2 Principle.16 A.3 Terms and definitions.16 A.4 Determination of solar reflectance, Rs.17 A.4.1 Reflectance spectra acquisition.17 A.4.2 Calculation of Rs.17 Annex B (normative)
Determination of neck-in characteristic.19 B.1 Introduction.19 B.2 Apparatus.19 B.3 Procedure.20 Annex C (normative)
Determination of perforation resistance.21 C.1 Principle.21 C.2 Description.21 C.3 Apparatus.21 C.4 Procedure.21 C.4.1 Definitions.21 C.4.2 Conditioning.21 C.4.3 Specimen preparation.21 C.4.4 Test conditions.22 C.4.5 Test procedure.22 C.4.6 Number of tests.22 C.5 Results.22 Annex D (normative)
Determination of tightening force.25 D.1 Principle.25 D.2 Apparatus.25 D.3 Procedure.25 D.4 Preparation of the specimens.25 D.5 Results.26 D.6 Repeatability.26 Annex E (normative)
Determination of adhesion characteristic.27 E.1 Principle.27 E.2 Apparatus.27 E.3 Preparation of apparatus.27 E.4 Procedure.32 Annex F (informative)
Determination of leaktightness on the bale.33 F.1 Airtightness on an artificial bale.33 F.2 Oxygen permeability on an artificial bale.33



EN 14932:2006 (E) 4 Foreword This document (EN 14932:2006) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the secretariat of which is held by IBN/BIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2007, and conflicting national standards shall be withdrawn at the latest by June 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.



EN 14932:2006 (E) 5 Introduction The biological and practical requirements for silage stretch films and the interactions with the machinery, used for the wrapping and handling of round bales, have been considered for the design of this European Standard. However, it is difficult to simulate in laboratory conditions some parameters like leak tightness, oxygen permeability, temperature and the manner they interact. In order to obtain a high quality for silage it is very important to restrict unwanted microbiological activities to very low levels. Carbon dioxide producing processes can be suppressed by high partial pressure of CO2 inside the bales. Aerobic processes are, of course, suppressed by low oxygen pressure. Consequently, the wrapped bale should be as gas tight as possible. Therefore this European Standard recommends using 6 layers of film as a minimum. This European Standard does not include as mandatory a test method for the determination of leak tightness on artificial bale. Nevertheless it is recommended for the manufacturers of stretch films to check this property near an appropriate testing laboratory. There are discussions regarding how the temperature inside the bale will influence how different types of "good" and "bad" microbiological activities will develop in forage. Although the film can be made of any colour, it is a fact that the pigmentation or colour itself will influence the temperature inside the bale, due to sun-radiation. Therefore, this European Standard also includes a method for the determination of the solar reflectance of stretch films.



EN 14932:2006 (E) 6 1 Scope This European Standard specifies the requirements for dimensional, mechanical and optical characteristics of stretch thermoplastic films for wrapping round bales used for outdoor ensiling of forage. This European Standard specifies classifications for durability and solar reflectance of stretch films for wrapping round bales. This European Standard specifies also test methods to check these requirements. This European Standard is applicable to white, black or coloured films based on polyethylene and/or ethylene copolymers. The range of film widths considered is from 250 mm up to 1 000 mm. NOTE 6 layers of stretch films, pre stretched up to 80 %, should be used for wrapping round bales. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 2155-5, Aerospace series — Test methods for transparent materials for aircraft glazing — Part 5: Determination of visible light transmission EN ISO 527-1, Plastics — Determination of tensile properties — Part 1: General principles (ISO 527-1:1993 including Corr 1:1994) EN ISO 527-3, Plastics — Determination of tensile properties — Part 3: Test conditions for films and sheets (ISO 527-3:1995) EN ISO 4892-2:2006, Plastics — Method of exposure to laboratory light sources — Part 2: Xenon-arc lamps (ISO 4892-2:2006) EN ISO 6383-2, Plastics — Film and sheeting — Determinations of tear resistance — Part 2: Elmendorf method (ISO 6383-2:1983) EN ISO 7765-1, Plastics film and sheeting — Determination of impact resistance by the free-falling dart method — Part 1: Staircase methods (ISO 7765-1:1988) ISO 4592, Plastics — Film and sheeting — Determination of length and width ISO 4593, Plastics — Film and sheeting — Determination of thickness by mechanical scanning ISO 9845-1, Solar energy — Reference solar spectral irradiance at the ground at different receiving conditions — Part 1: Direct normal and hemispherical solar irradiance for air mass 1,5 ISO 15105-2:2003, Plastics — Film and sheeting — Determination of gas-transmission rate — Part 2: Equal-pressure method



EN 14932:2006 (E) 7 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 width total width of the film when laid flat, given in millimetres 3.2 nominal width (W0) width declared by the manufacturer in millimetres 3.3 nominal thickness thickness of the film, as declared by the manufacturer, in micrometres (µm) 3.4 length of the film largest dimension of the film corresponding to the length of the un-winded roll, in metres 3.5 nominal length (L0) length of the film, as declared by the manufacturer, in metres 3.6 longitudinal direction of the film (MD) direction parallel to the length of the film corresponding to the extrusion direction 3.7 transverse direction of the film (TD) direction parallel to the width (at right angles to the length) 3.8 core protrusion distance from the edge of the roll to the edge of the core, in millimetres 3.9 neck-in (Ni) shrinkage of the film in the transverse direction (TD) induced by the stretching of the film in longitudinal direction (MD), in % (see 9.5) 3.10 tightening force force applied on the film after 10 min to maintain a tensile strain of a value of 50 %, in Newton (N) 4 Materials Stretch films for wrapping bales according this European Standard are usually manufactured from:  blends of low-density polyethylene (PE-LD) and linear low-density polyethylene (PE-LLD);  ethylene vinyl acetate copolymers (EVAC) and their blends with PE-LD or PE-LLD;  ethylene butyl acrylate copolymers (EBAK) and their blends with PE-LD or PE-LLD.



EN 14932:2006 (E) 8 5 Solar reflectance The solar reflectance of stretch films is defined by the classes “High reflectance” and “Low reflectance”. This classification, given in Table 1, is depending of the value of solar reflectance measured on one layer of unstretched film according to Annex A. The class of solar reflectance shall be declared by the manufacturer.
Table 1 — Classification according to solar reflectance Class of film Solar reflectance Rs % High reflectance ≥ 28 Low reflectance < 28
6 Durability The durability of stretch films is defined by the classes A and B. This classification, given in Table 2, is depending of the duration of exposure of the film to an artificial weathering, conforming to 9.13, which induces a decrease of the value of tensile strain at break equal or less than 50 % of the initial value. The class of durability shall be declared by the manufacturer. Table 2 — Classification according to artificial weathering Class of film Duration of exposure h A 1 400 B 2 500
NOTE Usually an empirical correlation between the durations of stretch films exposed to artificial weathering (according to 9.13) and the durations of natural weathering is the following:  Class A corresponds to an exposure of 1 year in the North of Europe;  Class B corresponds to an exposure of 1 year in the South of Europe. 7 Airtightness and oxygen permeability on bale The final result of silageing is very much depending on the total airtightness of the bale. There are a lot of parameters involved that can influence measurable properties as film permeability, cling force, holding force, but also properties that is difficult to measure with laboratory equipment such as wrinkles, tiger stripes, film appearance when stretched and others. Annex F gives guidance for assessing the airtightness and the oxygen permeability on an artificial bale.



EN 14932:2006 (E) 9 8 Requirements 8.1 General requirements Stretch films shall fulfil the requirements of Table 3. The nominal thickness and nominal width shall be declared by the manufacturer. Table 3 — Requirements for stretch films for wrapping round bales Characteristics Unit Requirements Test method Appearance
Regular See 8.2 Nominal thickness µm ≥ 25
Tolerance of average thickness/ nominal thickness % - 8, + 12 ISO 4593 Tolerance of single point thickness/ nominal thickness % - 20, + 28 ISO 4593 Nominal width W0 mm 250 ≤ W0 ≤ 1 000
Width tolerance mm W0 - 5 ≤ W0 ≤ W0 + 5 ISO 4592 Core protrusion mm Min 3, Max 10 See 9.3 Length of film m ≥ 99,0 % L0 See 9.4 Neck-in % < 25 See 9.5 Tensile stress at break in (MD) in (TD)
MPa MPa
≥ 25 ≥ 23
EN ISO 527-3 Tensile stress at yield in (MD,TD)
MPa
≥ 9
EN ISO 527-3 Tensile strain at break in (MD) in (TD)
% %
≥ 400 ≥ 600 EN ISO 527-3 Impact resistance g ≥ 120 Method A of
EN ISO 7765-1 Perforation resistance properties Maximum force
Total energy
N
J
≥ 4
≥ 0,04 Annex C Tightening force N ≥ 1,75 Annex D Tear resistance cN ≥ 120 in MD ≥ 400 in TD EN ISO 6383-2 Adhesion cN > 300 Annex E Total light transmission % < 75
EN 2155-5 Coefficient of oxygen permeability a cm³ /(m²
24 h) < 1 400 Annex A of ISO 15105-2:2003 a
Checked on 6 layers of un-stretched film.



EN 14932:2006 (E) 10
8.2 Requirement for appearance The edges of the reels shall be straight. The winding shall be without bubbles and wrinkles affecting film quality on the face of the roll. The film shall be homogeneous and free from visible defects which may affect the fitness for purpose of the stretch film: check by unrolling at least 2 m of the film and examining it against the light holding it tight at arms length. 9 Test methods 9.1 Determination of thickness The thickness of the single points and average thickness of the film shall be determined in accordance with ISO 4593. The test is performed using one strip of film cut in transverse direction of the roll (TD). 9.2 Determination of width The width of the film shall be determined in accordance with ISO 4592. 9.3 Determination of core protrusion The core protrusion shall be measured on each side of the roll. The value shall be expressed in mm. 9.4 Determination of length of film The length of the film shall be determined by unwinding the roll with a calibrated reel in contact continuously with its outside surface (see Figure 1). The calibrated reel is connected to a revolution counter. The diameter of the calibrated reel is measured with an accuracy of ± 0,2 %. The roll is totally unwound at a speed of
100 m/min ± 10 m/min. The value of the length of the film is calculated with the following equation: l = n
x
π d where  l is the value of the length of the film, expressed in m;  n is the number of revolutions of the calibrated reel during the total unwinding of the roll;  d is the value of the diameter of the calibrated reel, expressed in m.



EN 14932:2006 (E) 11
Key 1 roll to be tested 2 calibrated reel with a revolution counter 3 collection reel Figure 1 — Apparatus for the determination of the length of the film
9.5 Determination of neck-in The neck-in shall be determined in accordance with Annex B. The result is expressed as the shrinkage in transverse direction in percentage of the original width. Ni = [(W1 – W2) / W1] x 100 where  Ni is the value of neck in expressed in %,  W1 is the measure of width of the un-stretched film according to 9.2,  W2 is the measure of width of the stretched film on the bale. 9.6 Determination of tensile characteristics The tensile characteristics shall be determined according to EN ISO 527-1 and EN ISO 527-3 using five test pieces type 2, with a width of 10 mm, cut in each direction of the film, longitudinal direction (MD) and transversal direction (TD), at a testing speed of 500 mm/min. Calculate the arithmetic average value of the five measurements. The arithmetic average value shall fulfil the requirements of Table 3, as applicable. 9.7 Determination of impact resistance Impact resistance shall be determined in accordance with EN ISO 7765-1, method A. The test is performed on the film with the inside of the film, as seen from the reel, facing up. The value shall fulfil the requirement of Table 3. 9.8 Determination of slow perforation characteristics The slow perforation characteristics shall be determined in accordance with Annex C.



EN 14932:2006 (E) 12 9.9 Determination of the tightening force of films The tightening force shall be determined in accordance with Annex D. 9.10 Determination of tear resistance characteristics The tear resistance characteristics shall be determined in accordance with EN ISO 6383-2, on five test pieces cut from the un-stretched film in each direction of the film, longitudinal direction (MD) and transverse direction (TD). Calculate the arithmetic average value of the five measurements, expressed in N. The arithmetic average value shall fulfil the requirements of Table 3, as applicable. 9.11 Determination of adhesion The adhesion shall be determined in accordance with Annex E and expressed as the force needed to separate two film layers. Calculate the arithmetic average value of the 3 measurements, expressed in cN. The arithmetic average value shall fulfil the requirement of Table 3. 9.12 Determination of total light transmission The total light transmission shall be determined in accordance with EN 2155-5 on one layer of un-stretched film specified as a mean value from five specimens cut from the silage stretch film. 9.13 Determination of resistance to artificial weathering 9.13.1 Principle This test method is intended to measure the variation of the tensile strain at break of the film after an exposure to a xenon arc light source, that simulates the spectral power distribution of solar light, conforming to
EN ISO 4892-2, with test conditions according to 9.13.3, or to other correlated methods. Other test methods and/or test conditions for artificial weathering may be used only when a correlation between these test methods and/or test conditions and the test method conforming to EN ISO 4892-2 with test conditions according to 9.13.3 can be shown. 9.13.2 Apparatus The apparatus is described in EN ISO 4892-2:2006. It consists of Xenon arc sources with double borosilicate filter for simulating the direct sunlight. 9.13.3 Test conditions Irradiance: At the wavelength of 340 nm, the spectral irradiance is fixed at 0,35 W/(m2 * nm). In this condition, the irradiance is about 400 W/m2 in the visible wavelength range (300 nm to 800 nm).  Spray cycle: • duration of spraying: 18 min ± 0,5 min; • dry interval between spraying: 102 min ± 0,5 min.



EN 14932:2006 (E) 13  Black standard temperature: 65 °C ± 3 °C.  Relative humidity: 65 % ± 5 %.  Backing of the sample: stainless steel plate. 9.13.4 Sampling Five samples are exposed to artificial weathering. 9.13.5 Test procedure Irradiate the 5 test pieces with the apparatus conforming to 9.13.2 and in the test conditions according to 9.13.3 for the duration corresponding to the class declared by the manufacturer. After irradiation, measure the tensile strain at break on the test pieces cut from the exposed samples, according to EN ISO 527-1 and EN ISO 527-3, using five test pieces type 2 with a width of 10 mm, taken longitudinally (MD), at a test speed of 500 mm/min. NOTE It is not advised to take samples from the most outer area of the irradiated film sample. 9.13.6 Results Calculate the arithmetic mean value of the 5 measurements performed on the test pieces cut from the exposed samples and the arithmetic mean value of the 5 measurements performed on the test pieces cut from the non exposed samples in longitudinal direction (MD) (see 9.6). Compare these 2 values. The test is considered successful when the value calculated for samples exposed to artificial weathering is equal or greater than 50 % of the value calculated for non exposed samples. 9.14 Determination of oxygen permeability Oxygen permeability shall be determined in accordance with Annex A of ISO 15105-2:2003. The test shall be performed with six layers of un-stretched film and at a temperature of 23 °C ± 2 °C. 10 Determination of leaktightness on the bale The leaktightness of stretch films on an artificial bale should be checked in accordance with Annex F. 11 Designation Film designation shall include the following information:  purpose of the film: STRETCH FILM FOR WRAPPING BALES  reference to this European Standard, i.e. EN 14932;  nominal width in mm;  nominal thickness in µm;



EN 14932:2006 (E) 14  nominal roll length in m;  classification to solar
...