GB/T 26395-2024Water based gravure ink for cigarette packing (English PDF)

1 Scope

This document lays down the requirements, inspection rules, marking, labelling, packaging, transport and storage of water based gravure ink for cigarette packing, and describes the test methods.

This document applies to the quality control of water based gravure ink for cigarette packing used in rotary and sheet-fed gravure printing.

3 Terms and definitions

3.1 volatile organic compounds, VOCs - any organic compound whose initial boiling point at the standard pressure of 101.3 kPa is 250 °C or lower. Source: HJ 2542-2016, 3.2.

3.2 transfer primer coat - the liquid substance coated or printed on the surface of the substrate so that the metallized layer or its own ink film can be transferred completely. Source: GB/T 15962-2018, 2.63, modified.

3.3 peel - the force required to peel the transfer primer coat off the printing substrate with adhesive tape.

3.4 peeling - the state shown by the ink film after the transfer primer coat has been peeled off the printing substrate.

4 Requirements

4.1 Technical performance. The technical performance of the products shall comply with Table 1. Table 1 covers six products in parallel columns - the ink itself, the overprint varnish, the reducer, the gold medium, the primer and the transfer primer - and fixes the following. Appearance, for all six: a uniform fluid of consistent colour, free from skinning, lumps and obvious settling. Colour, for the ink only: grade 4 or better. Fineness of grind, for the ink only: not more than 20 µm. Viscosity, in seconds with the Zahn no. 2 cup, for each of the six in turn: 17 to 70 for the ink, 25 to 70 for the overprint varnish, 14 to 60 for the reducer, 20 to 70 for the gold medium, 14 to 60 for the primer and 14 to 60 for the transfer primer. Tinting strength, for the ink only: 95 % to 105 %. Adhesion: not less than 90 % for the ink, the overprint varnish, the reducer, the gold medium and the primer, with no requirement for the transfer primer. Peel force, for the transfer primer only: not more than 0.2 N per 25.4 mm. Peel behaviour, for the transfer primer only: slight force needed at the start of peeling, the edge of the ink film even and not sharp, a small fringe of 1 mm to 3 mm, no residue left on the substrate, and no fine crazing after stretching. Light fastness, for the ink only: grade 4 or better. Heat resistance, for each of the six in turn: not less than 120 °C, 150 °C, 120 °C, 120 °C, 120 °C and 140 °C. Rub resistance, for the overprint varnish only: not less than 200 rubs. Content of specified aromatic amines, for the ink only: not more than 50 mg/kg where the ink is used for cigarette cartons and boxes, and not detected where it is used for tipping paper and inner liner paper. Formaldehyde content: not more than 50 mg/kg.

A footnote to Table 1 lists the specified aromatic amines: o-toluidine, 2,4-dimethylaniline, 2,6-dimethylaniline, o-anisidine, p-chloroaniline, 2,4,5-trimethylaniline, 2-methoxy-5-methylaniline, 4-chloro-o-toluidine, 2,4-diaminotoluene, 2,4-diaminoanisole, 2-naphthylamine, 4-aminobiphenyl, 2-amino-4-nitrotoluene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, benzidine, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethylbenzidine, 4,4'-diaminodiphenyl sulphide, 3,3'-dichlorobenzidine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dimethoxybenzidine and o-aminoazotoluene. Further footnotes explain that use for cartons and boxes means water based gravure ink for cigarette packing used for printing tobacco cartons and boxes, and that use for tipping paper and inner liner paper means such ink used for printing tobacco tipping paper and inner liner paper.

4.2 Maximum limits for volatile organic compounds. The maximum limits for volatile organic compounds in the products shall comply with Table 2: the VOCs content shall meet the requirements of GB 38507; the benzene content shall be not more than 1 mg/kg; the combined content of toluene, ethylbenzene and xylene shall be not more than 50 mg/kg; and the content of other volatile organic compounds shall be not more than 500 mg/kg. A note adds that in drawing the calibration curve, methanol, ethanol, n-propanol, isopropanol, ethyl acetate, isopropyl acetate, n-propyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone should be added when selecting the reference materials. A footnote defines other volatile organic compounds as n-butanol, propylene glycol methyl ether, ethylene glycol ethyl ether, propylene glycol ethyl ether, n-butyl acetate, styrene, ethylene glycol ethyl ether acetate and cyclohexanone.

4.3 Maximum limits for soluble harmful elements. The maximum limits for soluble harmful elements in the products shall comply with Table 3, expressed in milligrams per kilogram: antimony 60, arsenic 25, barium 1 000, cadmium 75, chromium 60, lead 90, mercury 60 and selenium 500.

5 Test methods

5.1.1 Sampling shall be carried out in accordance with GB/T 3186.

5.1.2 The tests shall be carried out at a temperature of 23 °C plus or minus 2 °C and a relative humidity of 65 % plus or minus 5 %, avoiding direct sunlight, avoiding contamination by chemicals, gases, vapours, dust and other substances that affect the test, and avoiding vibration and draught.

5.2 Appearance. Open the container, examine visually and observe while stirring.

5.3 Colour. Carried out in accordance with GB/T 13217.1.

5.4 Fineness of grind. Carried out in accordance with 6.2 of GB/T 13217.3-2022.

5.5 Viscosity. Carried out in accordance with clause 4 of GB/T 13217.4-2020.

5.6 Tinting strength. Carried out in accordance with GB/T 13217.1.

5.7 Adhesion. Carried out in accordance with clause 4 or clause 5 of GB/T 13217.7-2023; in case of arbitration, clause 4 of GB/T 13217.7-2023 applies.

5.8.1 Peel force, principle. The transfer primer is coated on the substrate and dried to form a primer film. A tape of a specified adhesive type (acrylate pressure sensitive adhesive) and a specified width (normally 25.4 mm) is stuck evenly and flat on the ink film, and a 180° T-peel is carried out at a given speed; the force at which the ink film layer separates from the substrate is the peel force at that specified width.

5.8.2 Peel force, apparatus and materials. Tensile tester, force measurement accuracy plus or minus 0.5 %, able to display the tensile value in real time and to take readings at any stage. Wire bar, wet film thickness 6 µm to 10 µm. Hair dryer, with hot air, about 1 000 W. Substrate: biaxially oriented polypropylene (BOPP) film, polyethylene terephthalate (PET) film and the like. Transparent tape: acrylate pressure sensitive adhesive, width 25.4 mm, peel adhesion to steel 30 N per 100 mm. Cutter. Pressing roller, mass about 2 kg.

5.8.3 Peel force, procedure. Draw down the transfer primer on the substrate with the wire bar, blow with hot air from the hair dryer at about 20 cm from the drawdown for about 10 s, and cut specimens 25.4 mm plus or minus 0.2 mm wide and 200 mm long. Stick the tape evenly and flat on the ink film of the specimen and press with the pressing roller three times back and forth. Lift a corner of the tape so that the ink film separates from the substrate. Set the speed to 300 mm/min plus or minus 50 mm/min and the width to 25.4 mm, fix the lifted corner of the tape and the separated substrate in the upper and lower grips respectively, the longitudinal axes of the tape and the substrate coinciding with the centre line of the grips and the tension being suitable, with the unpeeled part forming a T with the direction of pull. Carry out the test according to the operating procedure of the instrument, take the mean value after the pull has become steady, test two specimens in parallel, and where the difference between the two results is not more than 0.005 N per 25.4 mm take the mean.

5.9.1 Peel behaviour, principle. The transfer primer is coated on the substrate and dried to form a primer film; the state shown by the ink film after it has been peeled off by the tape is examined - whether the edge is even or sharp, whether there is a fringe and how wide it is, whether any ink film is left on the substrate and how much, and whether force is needed at the start of peeling and how much.

5.9.2 Peel behaviour, apparatus and materials. Wire bar, wet film thickness 6 µm to 10 µm. Hair dryer, with hot air, about 1 000 W. Substrate: BOPP film, PET film and the like. Transparent tape: acrylate pressure sensitive adhesive, width 25.4 mm, peel adhesion to steel 30 N per 100 mm.

5.9.3 Peel behaviour, procedure. Draw down the transfer primer on the substrate with the wire bar and blow with hot air from the hair dryer at about 20 cm from the drawdown for about 10 s. Stick the tape evenly and flat on the ink film. Holding the substrate down with one hand, lift the tape from the ink film with the other, sensing the force needed at the start of the peel, observing the state of the ink film on the tape and any residue of ink film on the substrate, then stretch the lifted ink film on the tape and observe its state.

5.10 Light fastness. Carried out in accordance with GB/T 22771.

5.11.1 Heat resistance, principle. The extent to which the ink film is damaged within a given temperature, pressure and time.

5.11.2 Heat resistance, apparatus and materials. Heat sealer, maximum temperature 180 °C or more, pressure 2 MPa or more. Hair dryer, with hot air, about 1 000 W. Wire bar, wet film thickness 6 µm to 10 µm. Substrate: coated paper or another printing substrate. Polyethylene terephthalate (PET) film.

5.11.3 Heat resistance, procedure. Draw down the ink on the substrate with the wire bar and blow with hot air from the hair dryer at about 20 cm from the drawdown for about 10 s. Set the pressure to 0.2 MPa, the time to 1 s and the temperature of the lower sealing bar to 40 °C, and start the temperature of the upper sealing bar at 120 °C, raising it in steps of 10 °C. Lay PET film over the inked face of the drawdown, heat seal on the heat sealer, lift the PET film and observe the damage to the ink film. Compare with a blank specimen: the highest temperature at which no change of the ink film can be seen is the heat resistance temperature of that ink. Two parallel tests are carried out and the results shall agree.

5.12.1 Rub resistance, principle. The extent to which the ink film is damaged after rubbing against a test paper a given number of times under a given pressure.

5.12.2 Rub resistance, apparatus and materials. Rub tester, the rubbing block moving in a straight reciprocating motion. Hair dryer, with hot air, about 1 000 W. Wire bar, wet film thickness 6 µm to 10 µm. Substrate: coated paper or another printing substrate. Offset printing paper complying with GB/T 30130.

5.12.3 Rub resistance, procedure. Draw down the overprint varnish on the substrate with the wire bar, blow with hot air from the hair dryer at about 20 cm from the drawdown for about 10 s, cut a specimen 300 mm by 60 mm and fix it on the rubber holding plate. Cut the offset printing paper into a test paper 290 mm by 50 mm, fix it on the rubbing head and place a 2 kg weight on the swing arm. Set the number of rubs, starting at 200 and increasing in steps of 20. The number of rubs at which the ink film has not been damaged is the rub resistance of that ink. Two parallel tests are carried out and the results shall agree.

5.13 Content of specified aromatic amines. The content of each substance is determined in accordance with HG/T 4963.1.

5.14 Formaldehyde content. Carried out in accordance with GB/T 34683.

5.15.1 VOCs content. Carried out in accordance with GB/T 38608.

5.15.2 The content of benzene, toluene, ethylbenzene and xylene and the content of other volatile organic compounds are determined in accordance with Annex A.

5.16 Maximum limits for soluble harmful elements. Carried out in accordance with GB 24613.

6 Inspection rules

6.1.1 Batching. The unit product completed in one charge on a single machine or a machine set constitutes one batch.

6.1.2 Sampling. The product is sampled by the method of GB/T 3186; the sample shall be divided into two parts, one sealed and kept for reference and the other used as the inspection sample.

6.2 Classification of inspection. Product inspection is divided into factory inspection and type inspection.

6.3.1 Factory inspection. The items for factory inspection are appearance, colour, fineness of grind, viscosity, peel behaviour, the content of benzene, toluene, ethylbenzene and xylene, and the content of other volatile organic compounds.

6.3.2 Type inspection. The items for type inspection are all the items specified in the requirements of this document. Type inspection shall be carried out in any of the following cases: a) trial production and type approval of a new product or of an existing product transferred to another works; b) where there has been a substantial change of structure, material or process that may affect the performance of the product; c) after normal production has begun, the cycle for type inspection is one year; d) when production is resumed after a long suspension.

6.4 Decision rules. Where all the indicators of the inspection results comply with the requirements of this document, the batch is judged to have passed. Where one or more indicators do not comply with the requirements of this document, a double sample shall be taken again from the same batch and the failing items retested; where after retesting one or more items still do not comply with the requirements of this document, the batch is judged not to have passed.

7 Marking, labelling, packaging, transport and storage

7.1 Marking and labelling. The marking and labelling on the product packaging shall carry the trademark, the name and address of the enterprise, the product name, the product standard number, the model, the batch number, the date of production, the shelf life, the net content and the certificate of quality inspection; where the user so requires, a chemical safety data sheet shall be provided. The pictorial marking for packaging, storage and transport shall comply with GB/T 191.

7.2 Packaging. The product is packed in sealed plastic drums or in sealed steel drums with a plastic liner.

7.3 Transport. Where the packaging requirements of 7.2 are met, the product may be transported by vehicle, ship and other means, but during transport and handling it shall not be thrown, dropped or knocked, and shall be protected from rain and sun.

7.4 Storage. The product shall not be stored in the open; it shall be stored in a cool, ventilated warehouse, and there shall be no source of fire in the store. Under the specified storage conditions, the shelf life from the date of manufacture is six months for gold, pearlescent and other special effect inks and one year for the other products.

A Annex A (normative) Determination of benzene, toluene, ethylbenzene, xylene and other volatile organic compounds - Headspace gas chromatography

A.1 Principle. In a closed vessel at a given temperature, the volatile components in the test sample reach a partition equilibrium between the gas phase (headspace) and the matrix (liquid or solid phase). Once equilibrium has been reached, part of the gas phase is introduced into a gas chromatograph for separation, and after matrix correction the content of each volatile component in the test sample can be determined.

A.2 Reagents and materials. The reference substances, all of analytical grade, are benzene, toluene, ethylbenzene, xylene (ortho, meta and para), styrene, methanol, ethanol, n-propanol, isopropanol, n-butanol, propylene glycol methyl ether (1-methoxy-2-propanol), propylene glycol ethyl ether, ethylene glycol ethyl ether, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, ethylene glycol ethyl ether acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. The matrix correcting agent is triacetin, analytical grade.

A.2.3 Preparation of the reference solutions. Into a 250 mL volumetric flask add 20 mg to 30 mg each of benzene, toluene, ethylbenzene, xylene (ortho, meta and para) and styrene, and 200 mg to 300 mg each of methanol, ethanol, n-propanol, isopropanol, n-butanol, propylene glycol methyl ether (1-methoxy-2-propanol), propylene glycol ethyl ether, ethylene glycol ethyl ether, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, ethylene glycol ethyl ether acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, weighing each accurately to 0.1 mg, and make up to the mark with triacetin; this is the level 1 standard solution. Take 50.00 mL of the level 1 standard solution, transfer to a 250 mL volumetric flask and make up to the mark with triacetin; this is the level 2 standard solution. The level 3, level 4 and level 5 standard solutions are prepared in the same way, each from 50.00 mL of the preceding level. The standard solutions should be kept in a refrigerator at minus 18 °C and are valid for six months; they are brought out to room temperature and may only be used once they have reached it.

A.3 Apparatus and conditions. Static headspace sampler, headspace vial 20 mL to 25 mL, sample loop 3.0 mL, sample equilibration temperature 80 °C, sample loop temperature 100 °C, transfer line temperature 120 °C, sample equilibration time 45.0 min, vial pressurizing pressure 138 kPa, pressurizing time 0.2 min, filling time 0.2 min, sample loop equilibration time 0.05 min, injection time 1.0 min. Gas chromatograph with flame ionization detector (FID); VOC capillary column (VOCOL column, HP-VOC column or equivalent), 60 m by 0.32 mm internal diameter by 1.8 µm film thickness; carrier gas nitrogen of at least 99.995 % by volume; detector gases hydrogen of at least 99.995 % by volume and air of at least 99.995 % by volume; make-up gas the same as the carrier gas; injector temperature 150 °C; constant flow mode, column flow 3.8 mL/min, split ratio 10 to 1; temperature programme 40 °C held for 2 min, then raised at 4 °C/min to 180 °C and held for 15 min; detector conditions, temperature 250 °C, hydrogen 40 mL/min, air 450 mL/min, make-up gas 30 mL/min. Analytical balance, scale division 0.0001 g. Piston pipette, 1 000 µL. Volumetric flask, 250 mL. Pipette, 50 mL. Dropping tube, 1 mL.

A.4 Preparation of the test specimen. Specimen preparation is carried out at room temperature and normal pressure. The specimen shall be prepared quickly and accurately, and the sample shall be kept free from contamination. Two parallel specimens are prepared from each sample. About 0.5 mL of the ink to be tested is drawn up with the dropping tube, 0.04 g to 0.08 g (two to three drops) are weighed accurately into the headspace vial, 1 000 µL of triacetin is added, and the vial is sealed ready for testing.

A.5.1 Qualitative analysis. Each single reference substance is analysed by headspace gas chromatography to establish its retention time; all the reference substances are measured in turn and their retention times established. A typical chromatogram of the mixed reference substances is given in Figure A.1, whose peaks are identified in order as: 1 methanol; 2 ethanol; 3 isopropanol; 4 acetone; 5 n-propanol; 6 methyl ethyl ketone; 7 ethyl acetate; 8 isopropyl acetate; 9 n-butanol; 10 benzene; 11 propylene glycol methyl ether (1-methoxy-2-propanol); 12 n-propyl acetate; 13 ethylene glycol ethyl ether; 14 methyl isobutyl ketone; 15 propylene glycol ethyl ether; 16 toluene; 17 n-butyl acetate; 18 ethylbenzene; 19 p-xylene and m-xylene; 20 o-xylene; 21 styrene and ethylene glycol ethyl ether acetate; 22 cyclohexanone.

A.5.2 Quantitative analysis. To draw the working curve, 1 000 µL of triacetin is added to the headspace vial together with 1 000 µL of each of the level 1 to level 5 standard solutions in turn, and headspace gas chromatography (HS-GC) analysis is carried out. Each level of standard solution is measured twice and the mean taken. The corresponding working curve is established from the peak area and the content of the target compound, and the working curve is forced through the origin. For the determination of a sample, the specimen is prepared as described in this document and analysed by HS-GC, each sample being measured twice; the content of each component in the sample is calculated from the peak area of the corresponding component and the quantity of sample, and the mean is taken and reported to one decimal place.

A.6 Calculation. The content of the volatile organic compound to be determined in the sample is calculated by formula (A.1), in which the content of the compound in the sample is expressed in milligrams per kilogram (mg/kg), the peak area of the compound in the sample in integration units (U), the slope of the working curve of the compound in integration units per milligram (U/mg), the mass of the sample added to the headspace vial in grams (g), and 1000 is the conversion factor.

A.7 Precision. Under repeatability conditions, where the mean value is 15.0 mg/kg or more the relative deviation between the two determinations shall be less than 10 %; where the mean value is less than 15.0 mg/kg the absolute deviation between the two determinations shall be less than 1.5 mg/kg.