A method for predicting the thermal collapse situation and the remaining number of puffs during cigarette smoking

Abstract

The present invention discloses a method for predicting thermal collapse and the number of remaining puffs during cigarette smoking, wherein a color indicator layer is arranged on cigarette forming paper and / or tipping paper, wherein the color indicator layer is a thermochromic water-based dye layer. The present invention arranges a thermochromic water-based dye layer on cigarette forming paper and / or tipping paper, and the filter rod temperature can be judged by the color change of the thermochromic water-based dye layer, thereby predicting the thermal collapse and the number of remaining puffs. The thermochromic water-based dye prepared by the present invention is sensitive in color development, and the color is different when the temperature changes slightly between 70°C and 80°C. In addition, the color change temperature range of the thermochromic water-based dye prepared by the present invention matches the temperature in the post-smoking stage of the cigarette, which can meet the demand for predicting the filter rod temperature through the color indicator layer.

Description

Technical Field

[0001] The invention relates to the field of new materials for cigarettes, in particular to a method for predicting thermal collapse and the number of remaining puffs during cigarette smoking. Background Art

[0002] In the prior art, thermochromic technology is used to cover up the unpleasant yellow and brown color of conventional cigarette paper after heating, or to predict the temperature of cigarette filter rods through color changes.

[0003] During the continuous burning process of cigarettes, their hardness will gradually decrease. At the same time, the clamping and suction actions will exert a certain pressure on them, causing the cigarette to be deformed in shape. This phenomenon is called the thermal collapse of the cigarette filter rod. The thermal collapse of cigarettes seriously affects the appearance of cigarettes, and also causes the suction resistance to increase, making it difficult to smoke. There are many factors that affect the thermal collapse of cigarettes. Among them, the excessively high temperature of the filter rod when the cigarette is smoked is a very important factor. In the prior art, in order to obtain the temperature of the filter rod during the smoking process, some researchers will coat the tipping paper with thermochromic dyes to roughly judge the temperature by color changes. The problem with this method is that most of the thermochromic materials on the market are not sensitive to color. Only when the temperature changes greatly will there be obvious color changes, and it takes a long time for the color change to occur. Secondly, the existing thermochromic materials can only change color at higher temperatures, and the color change difference is not large when the temperature is low. The existing technology of direct hydrotalcite temperature sensing and color display is not sensitive. There will be obvious color change only when the temperature changes greatly, or the color change difference is not large. In other words, the current result of judging the temperature of cigarette filter rods by color display is not very accurate.

[0004] In addition, during the smoking process, consumers often do not know the remaining number of puffs and cannot predict the smoking progress. Near the end of the smoking process (1-2 puffs countdown), the filter rod temperature is approximately between 80-90°C. If the cigarette filter rod temperature can be accurately judged during the smoking process, the smoking progress can be roughly judged by the cigarette filter rod temperature.

[0005] In order to solve the above problems, the present invention is proposed. Summary of the invention

[0006] The full name of LDHs material is layered double hydroxide (LDH) material, which is a general term for hydrotalcite and hydrotalcite-like compounds.

[0007] LDHs materials are relatively common two-dimensional layered materials. The most typical LDHs compound is magnesium aluminum carbonate hydrotalcite, whose chemical composition is: Mg6Al2(OH) 16CO3·4H2O, whose structure is very similar to brucite [Mg(OH)2], forms a unit layer by sharing edges of MgO6 octahedrons. Mg located on the layer 2+ can be isomorphously substituted by Al within a certain range 3+ so that the layer board carries a positive charge and there is CO3 between the layers 2- to balance the positive charge on the layer board, making the overall structure of the LDHs material electrically neutral. The layer board and the interlayer anions of LDHs are connected by hydrogen bonds, which makes the interlayer anions of the LDHs material exchangeable.

[0008] The present invention provides a method for predicting the thermal collapse situation and the remaining number of puffs during cigarette smoking. A color indicating layer is provided on the cigarette forming paper and / or tipping paper. Among them, the color indicating layer is a temperature-induced reversible discoloration water-based dye layer. The temperature-induced reversible discoloration water-based dye includes a paraffin-carbonate LDHs intercalation material. The paraffin-carbonate LDHs intercalation material includes paraffin and hydrotalcite, and the interlayer anion of the hydrotalcite is carbonate.

[0009] Preferably, when the temperature-induced reversible discoloration water-based dye layer turns blue-violet, the filter rod becomes soft and is about to undergo collapse deformation, and the remaining number of puffs is 4-5; when the temperature-induced reversible discoloration water-based dye layer turns rose red, collapse deformation appears at the edge of the filter rod, and the remaining number of puffs is 1-2.

[0010] The preparation method of the temperature-induced reversible discoloration water-based dye includes the following steps:

[0011] (1) Prepare sodium paraffin;

[0012] (2) Prepare carbonate-type hydrotalcite;

[0013] (3) Make the interlayer anions of the sodium paraffin obtained in step (1) undergo an exchange reaction with the carbonate-type hydrotalcite obtained in step (2) to obtain a paraffin-carbonate LDHs intercalation material;

[0014] (4) Prepare a temperature-induced reversible discoloration water-based dye with the paraffin-carbonate LDHs intercalation material obtained in step (3) as the raw material.

[0015] Preferably, preparing sodium paraffin in step (1) includes the following steps:

[0016] (11) Mix paraffin with a reaction solvent and react to obtain a reactant;

[0017] (12) Evaporate the reaction solvent in the reactant and dry the obtained solid to obtain a sodium paraffin solid.

[0018] Steps (11) and (12) are specifically as follows: (11) In a 1-liter three-necked flask, add 100 - 150 g of paraffin solid and 500 - 600 ml of a 1:1 mixture of ethanol / sodium ethoxide, heat it on a constant-temperature heating platform to 78 - 85 °C, and stir well for 25 - 30 min to turn the paraffin into its sodium carboxylate, that is, change the carboxyl group at the end of the paraffin into a carboxylate anion to form sodium paraffin; (12) Evaporate the reaction solvent in the reactants using a rotary evaporator and dry the obtained solid in a vacuum drying oven to obtain a solid sodium paraffin salt.

[0019] Preferably, in step (11), specifically: Mix 100 - 150 g of paraffin solid and 500 - 600 ml of a 1:1 mixture of ethanol and sodium ethoxide, heat to 78 - 85 °C, stir for 25 - 30 min and then carry out the reaction, the stirring speed is 500 - 600 rpm, and the reaction time is 40 - 48 h; in step (12), the drying time is more than 5 hours. Preferably, the preparation of carbonate-type hydrotalcite in step (2) includes the following steps:

[0020] (21) Add deionized water to the autoclave and raise the temperature.

[0021] (22) Put magnesium oxide:aluminum hydroxide:sodium carbonate into the reaction kettle in step (21) according to the ratio and stir.

[0022] (23) Continue heating to raise the temperature inside the kettle. At this time, the pressure in the reaction kettle is the initial pressure. Introduce carbon dioxide gas into the reaction kettle until the pressure in the reaction kettle reaches 0.7 Mpa. When the pressure in the reaction kettle drops back to the initial pressure, continue to introduce carbon dioxide to 0.7 MPa, and cycle in turn until the total amount of carbon dioxide introduced reaches the ratio requirement.

[0023] (24) After the feeding is completed, continue the reaction.

[0024] (25) After the reaction is completed, cool down, then obtain the wet hydrotalcite material through filtration and washing, and then dry the wet hydrotalcite material to obtain a carbonate hydrotalcite product.

[0025] Preferably, in step (21), raise the temperature to 80 °C; in step (22), the ratio of magnesium oxide:aluminum hydroxide:sodium carbonate is 2:1:0.0015 - 2:1:0.002; in step (23), raise the temperature inside the kettle to 160 - 180 °C, the initial pressure is 0.6 Mpa, and the total amount of carbon dioxide introduced is carbon dioxide:aluminum hydroxide 25:1; in step (24), carry out the reaction at a reaction temperature of 150 - 160 °C for 10 - 11 h; in step (25), the drying temperature is 110 - 120 °C and the drying time is 4.5 - 5 h.

[0026] Preferably, step (3) is: mixing sodium paraffin wax salt with LDHs and reacting, followed by suction filtration and drying to obtain a paraffin-LDHs intercalation material;

[0027] The reaction conditions are: a feed ratio of 1:1, a stirring speed of 500 - 600 rpm, a reaction temperature of 60 - 70 °C, and a reaction time of 40 - 48 h; the drying temperature is 20 - 30 °C, and the drying time is 5 - 6 h.

[0028] Preferably, step (4) is: mixing polyvinyl alcohol, Silok-7170W, Silok-8000, and water, heating to 50 °C and stirring to dissolve, slowly adding sodium alginate under stirring conditions, cooling to room temperature after complete dissolution, adding the paraffin-LDHs intercalation material, continuing to stir for 1 h, ball milling for 8 h, and then air-drying the product at room temperature to obtain paraffin-LDHs dye.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention provides a thermochromic reversible water-based dye layer on the cigarette forming paper and / or tipping paper. The temperature of the filter rod can be judged by the color change of the thermochromic reversible water-based dye layer, so as to predict the heat collapse situation and the remaining number of puffs. When the thermochromic reversible water-based dye layer turns blue-violet, the filter rod becomes soft and is about to collapse, and the remaining number of puffs is 4 - 5; when the thermochromic reversible water-based dye layer turns rose red, the edge of the filter rod shows a collapse deformation, and the remaining number of puffs is 1 - 2. The thermochromic reversible water-based dye prepared by the present invention has sensitive color development. With slight temperature changes of 70 °C and 80 °C, the color is different. In addition, the thermochromic temperature range of the thermochromic reversible water-based dye prepared by the present invention matches the temperature in the later stage of cigarette smoking, which can meet the requirement of predicting the filter rod temperature through the color indicator layer.

[0031] 2. The present invention prepares a powdery dye by intercalating paraffin with inorganic layered double metal hydroxides, and then uses it as a color-developing raw material to prepare a water-based dye with polyvinyl alcohol, Silok-7170W, Silok-8000, etc. Coating the water-based dye on the forming paper can avoid direct contact between the lip end and the color-developing raw material and prevent the color-developing raw material from volatilizing and losing due to long-term exposure to the air.

[0032] 3. Hydrotalcite can undergo a color change reaction by itself under ultraviolet light polymerization, but the temperature at which the color change occurs is relatively high and the color change is irreversible, that is, the color does not recover after the temperature returns. To solve this problem, in the present invention, sodium paraffin and hydrotalcite are subjected to an intercalation reaction to obtain a paraffin-carbonate type hydrotalcite intercalation material. Then, an aqueous dye is prepared using this material as a raw material. When this aqueous dye is coated on the filter rod forming paper and undergoes ultraviolet light polymerization, a color change reaction will occur when the temperature rises, and it will return to the original color after the temperature drops. The aqueous dye of the present invention has excellent color change effect and color change reversibility.

[0033] 4. Specifically regarding the preparation method of hydrotalcite and the type of anions, the nitrate type LDHs synthesized by the alkali method are hard in texture after drying, and the color change is uneven when prepared into a water-soluble dye. For the carbonate type LDHs prepared by the urea method, the color change is not obvious after heating, and the color change is not obvious after cooling, making it difficult to accurately predict the temperature of the forming paper. For the non-urea method carbonate type LDHs, the color change is obvious, but the color development process is irreversible. However, the paraffin-carbonate type LDHs intercalation dye obtained by reacting the carbonate type LDHs prepared by the non-urea method with sodium paraffin in the present invention has an obvious color development effect and a good color recovery effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 For the heating color change and cooling recovery of the carbonate type LDHs dye in Example 1;

[0035] Figure 2 For the heating color change and cooling recovery of the paraffin-nitrate type LDHs intercalation dye in Example 2;

[0036] Figure 3 For the color of the paraffin-carbonate LDHs intercalation dye before heating in Example 3;

[0037] Figure 4 For the heating color change and cooling recovery of the paraffin-carbonate LDHs intercalation dye in Example 3;

[0038] Figure 5 For the color change effect (before color change, during color change, after color change) of the paraffin-carbonate LDHs intercalation dye coated on the forming paper in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following examples are used to further elaborate on the present invention in detail. It should be understood that the specific examples described herein are only used to explain the present invention and do not limit the technical solutions of the present invention.

[0040] Comparative Example 1: Preparation of carbonate type LDHs by the urea method

[0041] Raw materials: magnesium nitrate, aluminum nitrate, urea, deionized water;

[0042] Dosage: Add magnesium nitrate: aluminum nitrate: urea in a ratio of 0.04:0.08:1 to 800 ml of deionized water.

[0043] Reaction conditions: 120 °C, 48 h.

[0044] Product recovery: After the reaction, filter off the excess water by suction filtration, wash with deionized water and filter by suction three times, then soak in absolute ethanol overnight, filter off the excess ethanol, dry in a vacuum drying oven for 5 h, and grind into powder with a cyclone mill.

[0045] Comparative Example 2: Synthesis of nitrate-type LDHs by the alkaline method

[0046] Raw materials: magnesium nitrate, aluminum nitrate, anhydrous sodium carbonate, sodium hydroxide.

[0047] Experimental method: Dissolve 2 parts of magnesium nitrate and 1 part (0.05 mol) of aluminum nitrate in 70 ml of deionized water in advance, denoted as solution A; dissolve 2 parts of anhydrous sodium carbonate and 0.35 mol of sodium hydroxide in 100 ml of deionized water, denoted as solution B; slowly drip solution B into solution A under stirring (7 ml / min) with a dropping funnel, and immediately start heating after dripping, stir in an oil bath at 65 °C for 15 h.

[0048] Product recovery: After the reaction, obtain a paste-like hydrotalcite, remove the excess water with a centrifuge, wash three times with deionized water and absolute ethanol respectively, and also remove the excess liquid with a centrifuge, and place it in a vacuum drying oven to dry overnight.

[0049] The hydrotalcite prepared by this method is hard after drying, and is ground into powder with a cyclone mill with strong pressure to obtain nitrate-type hydrotalcite.

[0050] Example 1: Preparation of carbonate-type LDHs by the non-urea method

[0051] Step 1: Add 25.00 kg of deionized water to a 60 L autoclave and heat to 80 °C;

[0052] Step 2: Charge magnesium oxide: aluminum hydroxide: sodium carbonate into the above reaction kettle in a ratio of 2 parts: 1 part: 0.0015 part and stir;

[0053] Step 3: Continue heating until the temperature in the kettle reaches 160 °C, and the pressure in the reaction kettle is about 0.6 Mpa at this time. Introduce carbon dioxide gas into the reaction kettle until 0.7 Mpa, and when the pressure drops back to 0.6 Mpa, continue to introduce carbon dioxide until 0.7 Mpa, and repeat in turn. The total amount of carbon dioxide introduced is 1.10 kg (25.00 mol);

[0054] Step 4: After the feeding is completed, continue the reaction at 160 °C for 10 h;

[0055] Step 5: After cooling, the hydrotalcite wet material is obtained by filtration and washing, and dried at 120 °C for 5 h to obtain the carbonate hydrotalcite product.

[0056] Example 2: Preparation of paraffin-nitrate LDHs intercalated dye

[0057] Step 1: Preparation of sodium paraffin

[0058] Paraffin is mixed with a reaction solvent, the reaction solvent is ethanol, the feeding ratio is 1:1.39, the reaction temperature is 60 °C, and it is stirred in an oil bath at 500 rpm for 48 h. Then the solvent is evaporated to dryness with a rotary evaporator and placed in a vacuum drying oven for drying for more than 5 hours. The paraffin is treated with an ethanol / sodium ethoxide system to make it into a carboxylate salt of sodium, that is, the carboxyl group at the end of the paraffin is changed into a carboxylic acid anion to form sodium paraffin.

[0059] Step 2: 2 parts of magnesium nitrate and 1 part (0.05 mol) of aluminum nitrate are added to 70 ml of deionized water for pre-dissolution, denoted as solution A;

[0060] Step 3: 2 parts of anhydrous sodium carbonate and 0.35 mol of sodium hydroxide are added to 100 ml of deionized water for dissolution, denoted as solution B;

[0061] Step 4: Solution B is slowly dropped into the stirring solution A (7 ml / min) with a dropping funnel. Immediately after dropping, heating is started, and it is stirred in an oil bath at 65 °C for 15 h to obtain a paste-like hydrotalcite for standby.

[0062] Step 5: The excess water is removed by a centrifuge, washed three times each with deionized water and absolute ethanol, and the excess liquid is also removed by a centrifuge, and then placed in a vacuum drying oven to dry overnight to obtain paraffin-nitrate hydrotalcite.

[0063] Example 3: Preparation of paraffin-carbonate LDHs intercalated dye

[0064] Step 1: Preparation of sodium paraffin

[0065] Paraffin is mixed with a reaction solvent, the reaction solvent is ethanol, the feeding ratio is 1:1.39, the reaction temperature is 60 °C, and it is stirred in an oil bath at 500 rpm for 48 h. Then the solvent is evaporated to dryness with a rotary evaporator and placed in a vacuum drying oven for drying for more than 5 hours. The paraffin is treated with an ethanol / sodium ethoxide system to make it into a carboxylate salt of sodium, that is, the carboxyl group at the end of the paraffin is changed into a carboxylic acid anion to form sodium paraffin. For the anion exchange reaction with the LDHs material interlayer anion in Example 1.

[0066] Step 2: Preparation of paraffin-carbonate LDHs intercalated material

[0067] Take the product of Example 1, add 200 ml of water, and after ultrasonic oscillation for 10 min, a carbonate hydrotalcite dispersion is formed to obtain a carbonate-type hydrotalcite intercalation material.

[0068] Mix the paraffin sodium salt of the product in Example 1 with the LDHs in Example 1 at a feeding ratio of 1:1, and stir and react in an oil bath at 500 rpm and 60 °C for 48 h. Filter and dry to obtain the corresponding paraffin-LDHs intercalation material. During the preparation process, an intercalation reaction occurred between paraffin and LDHs, that is, the carboxylate anions of paraffin replaced the interlayer carbonate ions (CO3 2- ) of the LDHs material.

[0069] During the preparation process, an intercalation reaction occurred between paraffin and LDHs, and the carboxylate anions of paraffin replaced the interlayer anions (CO3 2- ) of the LDHs material. Obviously, the solubility of paraffin carboxylate ions in water is extremely poor. In contrast, the solubility of the interlayer anions of the LDHs materials in Comparative Example 1, Comparative Example 2, and Example 1 in water is relatively good. The difference in the solubility of the two ions in water is the driving force for this step of the reaction.

[0070] Respectively, take the hydrotalcite or paraffin-hydrotalcite intercalated dye prepared in the comparative examples and examples as the color-developing raw materials, and prepare them into waterborne coatings according to the following method. Print the obtained waterborne coatings on the formed paper, and investigate their color-changing effects and color-changing reversibility.

[0071] 1. Preparation of waterborne coatings

[0072] Raw materials: polyvinyl alcohol 088-05, sodium alginate, hydrotalcite or paraffin-hydrotalcite intercalated dye prepared in the comparative examples and examples, Silok-7170W (dispersant), Silok-8000 (wetting agent), deionized water;

[0073] Preparation method: Take 10 g of polyvinyl alcohol, 0.2 g of Silok-7170W, 0.2 g of Silok-8000, and an appropriate amount of water, heat to 50 °C and stir to dissolve. Slowly add 1 g of sodium alginate under stirring. After dissolution, cool to room temperature, add 10 g of hydrotalcite or paraffin-hydrotalcite intercalated dye prepared in the comparative examples and examples, and add deionized water to make up the balance to 100 g. Stir for 1 h and ball mill for 8 h. After standing at room temperature and air-drying, the product is different waterborne coatings.

[0074] 2. UV polymerization

[0075] For UV polymerization, coat the waterborne coating on the filter paper, irradiate with 254 nm UV light for 1-2 min, place it in a ventilated place and air-dry naturally for 24 h, and then cut and load into plates.

[0076] 3. Test of reversible color-changing effect

[0077] During the ultraviolet light polymerization process, observe and record the color changes. Then, heat the irradiated product with a hot air gun and observe and record the color changes. Take it out of the oven and let it stand still to cool naturally, and observe and record the color changes. Repeat the heating-cooling-heating-cooling process and observe and record its reversible color-changing performance.

[0078] Test the color development effects of the above comparative samples and example samples, and the results are as follows:

[0079] (1) Comparative Example 1: Preparation of carbonate-type LDHs by the urea method

[0080] Color-changing effect: The color change is not obvious after heating, and the color change is not obvious after cooling.

[0081] (2) Comparative Example 2: Synthesis of nitrate-type LDHs by the alkali method

[0082] Color-changing effect: The hydrotalcite prepared by this method is hard in texture after drying. The color change of the water-soluble dye prepared is more obvious than that of Comparative Example 1, but the color change is uneven and the colors are inconsistent after heating.

[0083] (3) Example 1: Non-urea method carbonate-type LDHs

[0084] The intercalated powder of the prepared carbonate LDHs is blue ( Figure 1 the left figure in the middle), and after ultraviolet light polymerization, when heated to 150 °C, the color change can be seen. After being heated multiple times and returning to room temperature, it becomes purple-black ( Figure 1 the right figure in the middle). This is because after a small part of the powder changes color to dark purple when heated, irreversible color change occurs. Therefore, the preparation of water-soluble dye is not carried out, and the coating of forming paper cannot be carried out either.

[0085] (4) Example 2: Paraffin-nitrate-type LDHs intercalated dye

[0086] The paraffin-nitrate-type LDHs intercalated dye is originally pink ( Figure 2 the left figure), and after ultraviolet light irradiation, it turns into blue-violet. After high-temperature baking, it gets bright orange ( Figure 2 the middle figure), and after removing the heat source and cooling, it gets purplish red ( Figure 2 the right figure), and this effect can be obtained through multiple heating-cooling cycles. However, the paraffin-nitrate-type LDHs intercalated dye is similar to the nitrate-type LDHs, with a hard texture and uneven color change. In addition, the colors before and after the color change of the paraffin-nitrate-type LDHs intercalated dye are relatively close in color system, and it is not easy to observe the subtle changes.

[0087] (5) Example 3: Paraffin-carbonate-type LDHs intercalated dye

[0088] AsFigure 5 As shown, after irradiation with 254 nm ultraviolet light, the paraffin-LDHs intercalated dye changes from pink ( Figure 3 ) to blue-violet ( Figure 4 left figure). After heating, it changes from blue-violet to rose red ( Figure 4 middle figure). When the heat source is removed and cooled to room temperature, the color first returns to blue-violet ( Figure 4 right figure). The color change effect is obvious and the reversibility is good, and it can return to blue-violet. In addition, compared with the paraffin-nitrate type LDHs intercalated dye, the color change of the paraffin-carbonate type LDHs intercalated dye before and after color change is obvious, and it is easy to observe subtle changes.

[0089] To verify the uniformity of large-area color change of the paraffin-carbonate type LDHs intercalated dye, this dye was coated on the forming paper, using an offline coating process, and the coating was polymerized by irradiation with an ultraviolet curing machine, and fixed with clips in a blast drying oven. Specifically: Preparation of reversible color-changing forming paper and tipping paper: Coating of water-based dye tipping paper, using gravure or flexographic printing process, and printing the water-based dye obtained in step three onto the forming paper base paper with a basis weight of 25 g / m 2 according to a printing amount of 0.05 - 0.1 g / m 2 according to the preset pattern; Ultraviolet polymerization: Ultraviolet polymerization, coating the water-based coating on the filter paper, irradiating with 254 nm ultraviolet light for 1 - 2 min, placing it in a ventilated place to dry naturally for 24 h, cutting and loading into trays to obtain thermochromic forming paper or tipping paper.

[0090] Heat it to different temperatures (40 °C - 100 °C) with a blast drying oven. After the temperature reaches the set temperature, keep the temperature for 10 min to make the internal temperature of the oven reach a stable state, observe and record the color change; Open the oven door and cool for 2 - 3 min, observe and record the color change after cooling. The results are shown in Figure 5 , which is consistent with the results on the filter paper. The filter paper printed with the water-based coating of the paraffin-LDHs intercalated material has an original color of blue-violet after ultraviolet polymerization, changes from blue-violet to rose red after heating, and when the heat source is removed and cooled to room temperature, the color first returns to blue-violet. The color change effect is obvious and the reversibility is good, and the large-area color change uniformity is good.

[0091] Comparison of thermal stability between reversible color-changing forming paper and filter rod:

[0092] After preparing the filter rod with the forming paper coated with the water-based coating of the paraffin-LDHs intercalated material, place the filter rod in a blower to observe the temperature change. By sucking 150 cigarettes, observe the temperature and color development situation. The observation results are shown in Table 1:

[0093] Table 1 Comparison of temperature, color development situation, filter rod thermal collapse situation, and remaining puff numbers

[0094]

[0095] In summary, the nitrate-type LDHs synthesized by the alkali method of the present invention have a hard texture after drying, and the color change is uneven after being prepared into a water-soluble dye. The color change of carbonate-type LDHs prepared by the urea method is not obvious after heating, and the color change is not obvious after cooling, and it is difficult to accurately predict the temperature of the forming paper. The color change of carbonate-type LDHs by the non-urea method is obvious, but the color development process is irreversible. Paraffin-nitrate-type LDHs intercalation dye is similar to nitrate-type LDHs, with a hard texture and uneven color change. In addition, the color of the paraffin-nitrate-type LDHs intercalation dye before and after color change is relatively close in color system, and it is not easy to observe subtle changes. The paraffin-carbonate-type LDHs intercalation dye obtained by the reaction of carbonate-type LDHs prepared by the non-urea method and sodium paraffin has obvious color development effect and good color recovery effect. In addition, the color of the paraffin-carbonate-type LDHs intercalation dye before and after color change is clearly distinguished, and subtle changes are easy to observe.

[0096] Furthermore, the different colors of the thermochromic water-based dye layer indicate the different temperatures of the filter rod, thereby predicting the thermal collapse and the number of remaining puffs. When the thermochromic water-based dye layer turns blue-purple, the filter rod temperature is between 50°C and 60°C, the filter rod becomes soft and is about to collapse and deform, and the number of remaining puffs is 4-5, which reminds consumers that the puffing is approaching the end, and it is necessary to pay attention to appropriately reduce the bite force of the filter rod and reduce the force of pressing the filter rod to prevent the filter rod from deforming significantly. When the thermochromic water-based dye layer turns rose red, the filter rod temperature is between 80°C and 90°C, the edge of the filter rod collapses and deforms, and the number of remaining puffs is 1-2, which reminds consumers that the puffing is about to end.

Claims

1. A method for predicting the thermal collapse situation and the remaining number of puffing during cigarette smoking, characterized in that, A color indicating layer is provided on the cigarette forming paper and / or tipping paper. Among them, the color indicating layer is a heat-induced reversible discoloration water-based dye layer. The heat-induced reversible discoloration water-based dye includes a paraffin-carbonate LDHs intercalation material. The paraffin-carbonate LDHs intercalation material includes paraffin and hydrotalcite. The interlayer anion of the hydrotalcite is carbonate; When the heat-induced reversible discoloration water-based dye layer turns blue-violet, the filter rod is about to become soft, and the remaining number of puffs is 4-5; when the heat-induced reversible discoloration water-based dye layer turns rose red, a collapse deformation appears at the edge of the filter rod, and the remaining number of puffs is 1-2; The preparation method of the heat-induced reversible discoloration water-based dye includes the following steps: (1) Prepare sodium paraffin. (2) Prepare carbonate-type hydrotalcite, including the following steps: (21) Add deionized water to an autoclave and heat it to 80 °C; (22) Put magnesium oxide, aluminum hydroxide, and sodium carbonate into the reaction kettle in step (21) according to the ratio of magnesium oxide:aluminum hydroxide:sodium carbonate of 2:1:0.0015 - 2:1:0.002 and stir; (23) Continue heating, raise the temperature in the kettle to 160 - 180 °C. At this time, the initial pressure of the reaction kettle is 0.6 Mpa. Introduce carbon dioxide gas into the reaction kettle. The total amount of carbon dioxide introduced is carbon dioxide:aluminum hydroxide = 25:

1. When the pressure of the reaction kettle reaches 0.7 Mpa, wait for the pressure of the reaction kettle to drop back to the initial pressure, and then continue to introduce carbon dioxide to 0.7 Mpa. Repeat this process in turn until the total amount of carbon dioxide introduced reaches the required ratio; (24) After the feeding is completed, continue the reaction. The reaction temperature is 150 - 160 °C, and the reaction time is 10 - 11 h; (25) After the reaction is completed, cool down, then obtain the wet hydrotalcite material through filtration and washing, and then dry the wet hydrotalcite material. The drying temperature is 110 - 120 °C, and the drying time is 4.5 - 5 h to obtain carbonate-type hydrotalcite; (3) Make the sodium paraffin obtained in step (1) undergo an ion exchange reaction with the interlayer anion of the carbonate-type hydrotalcite obtained in step (2) to obtain a paraffin-carbonate LDHs intercalation material; (4) Use the paraffin-carbonate LDHs intercalation material obtained in step (3) as a raw material to prepare a heat-induced reversible discoloration water-based dye. The specific steps are as follows: Take polyvinyl alcohol, Silok-7170W, Silok-8000, and water, mix them, and heat to 50 - 60 °C and stir to dissolve. Slowly add sodium alginate under stirring conditions. After dissolution, cool to room temperature, add the paraffin-carbonate LDHs intercalation material, continue stirring for 1.0 - 1.2 h, ball mill for 8 - 8.5 h, and then place the product at room temperature to air dry to obtain the heat-induced reversible discoloration water-based dye.

2. The method according to claim 1, wherein Step (1) for preparing sodium paraffin includes the following steps: (11) Mix paraffin with a reaction solvent and react to obtain a reactant; (12) Evaporate the reaction solvent in the reactant and dry the obtained solid to obtain a sodium paraffin solid.

3. The method according to claim 2, characterized in that Specifically in step (11): Mix 100 - 150 g of paraffin solid, 500 - 600 ml of a mixed solution of ethanol and sodium ethoxide in a ratio of 1:1, heat to 78 - 85 °C, stir for 25 - 30 min and then carry out the reaction. The stirring speed is 500 - 600 rpm and the reaction time is 40 - 48 h; in step (12), the drying time is more than 5 hours.

4. The method according to claim 1, wherein In step (4), the ratio of polyvinyl alcohol, Silok-7170W, Silok-8000, sodium alginate and paraffin-carbonate LDHs intercalation material is 50:1:1:5:50.

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