High-barrier waterproof and oil-proof meal package paper and preparation method thereof

Abstract

The invention discloses high-barrier waterproof and oil-proof meal package paper and a preparation method thereof, and relates to the technical field of food packaging materials. The invention discloses a preparation method of high-barrier waterproof and oil-proof meal package paper, which comprises the following steps: coating raw paper with waterproof and oil-proof glue to obtain the high-barrier waterproof and oil-proof meal package paper, the waterproof and oil-proof glue comprises the following raw materials in percentage by weight: 1-2% of modified chitosan, 4-5% of carboxymethyl cellulose, 0.3-0.5% of nano cellulose, 0.15-0.25% of modified nano mesoporous silica, 0.3-0.42% of a bio-based cross-linking agent and the balance of a solvent, and the sum of the weight percentages of the raw materials is 100%. The prepared meal package paper is good in waterproof and oil-proof effects, and the folding strength of the coating is high.

Description

Technical Field

[0001] This invention relates to the field of food packaging materials technology, specifically to a high-barrier, waterproof, and oil-resistant dinner wrapping paper and its preparation method. Background Technology

[0002] Food packaging effectively ensures food safety by preventing food spoilage caused by air, bacteria, and moisture. Traditional plastic food packaging materials, made from polystyrene, release toxic and difficult-to-degrade substances at temperatures exceeding 100°C or under heating conditions. Furthermore, polystyrene monomers can migrate from the plastic into the food, posing a health risk. Paper, as a green, bio-based food packaging material that can replace plastic, can reduce pollution and ensure food safety. "Paper instead of plastic" has become a development trend in the food packaging industry. Paper is mainly composed of natural plant fibers, with its main chemical components being hydrophilic fibers and hemicellulose. Its molecular structure contains a large number of hydroxyl groups, resulting in a loose and porous structure with some liquid absorption. Compared to plastic materials, paper packaging has poorer barrier properties against air, water, and oils, limiting its suitability for packaging foods containing water or oil.

[0003] To meet the demands of food packaging, it is essential to treat it for water and oil resistance. Common methods for producing waterproof and oil-resistant food wrapping paper include internal pulp addition, surface coating, and surface plating. Internal pulp addition involves adding sizing agents to the pulp to enhance its water resistance. While easy to implement, the sizing agents and oil-resistant agents in the pulp are easily lost during the papermaking process, requiring the addition of retention aids, leading to resource waste and increased costs. Therefore, in recent years, surface treatment has become more popular for achieving waterproof and oil-resistant effects. Surface coating involves applying high-melting-point polymers such as PP, PE, and polyvinyl chloride (PVC) through a die onto the paper, uniformly covering its surface. After coating, these polymers form a dense film on the paper surface, covering the pores of the paper fibers and achieving water and oil resistance. Although PP and PE coating methods are inexpensive and easy to process, the coated paper comes into direct contact with food, and harmful substances may migrate into the food, posing a food safety hazard. Furthermore, the PP and PE materials in coated paper are difficult to degrade and recycle, making paper recycling challenging. Surface coating methods involve adhering waterproof and oil-resistant coatings to the paper base surface through methods such as impregnation and spraying, and then using rollers, doctor blades, or air knives to form a uniform coating, thus achieving waterproof and oil-resistant properties. Biodegradable biomass material coatings have become a research hotspot, as these coatings solve the problems of toxicity and difficulty in natural degradation associated with traditional materials. The application of polysaccharides in biomass material coatings has been a popular research direction in recent years. Common polysaccharides include starch, chitosan, sodium alginate, carboxymethyl chitosan, and nanocellulose. Most polysaccharides have good oil-resistant properties but also possess a certain degree of viscosity. To achieve ideal results, the solution concentration usually needs to be increased, but this results in too much flow resistance, which is detrimental to coating. Moreover, polysaccharides and oils have high surface energy. Although polysaccharides can form a dense barrier layer, oils will spread rapidly on the paper surface, resulting in poor wetting resistance of greaseproof paper. Summary of the Invention

[0004] The purpose of this invention is to provide a high-barrier, waterproof, and oil-resistant paper wrapper and its preparation method, thereby solving the following technical problems:

[0005] Existing polysaccharide biomass material coatings and oils have high surface energy. Although polysaccharides can form a dense barrier layer, oils will spread rapidly on the paper surface, resulting in poor wetting resistance of greaseproof paper.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper includes the following steps: coating a base paper with a waterproof and oil-resistant adhesive to obtain a high-barrier, waterproof, and oil-resistant dinner wrapping paper;

[0008] The waterproof and oil-resistant adhesive comprises the following raw materials by weight percentage: 1-2% modified chitosan, 4-5% carboxymethyl cellulose, 0.3-0.5% nanocellulose, 0.15-0.25% modified nano-mesoporous silica, 0.3-0.42% bio-based crosslinking agent, and the balance being solvent. The sum of the weight percentages of the raw materials is 100%.

[0009] As a further aspect of the present invention, the method for preparing modified chitosan includes the following steps:

[0010] In a nitrogen atmosphere, palmitic acid and anhydrous ethanol are added to a reaction flask, and the temperature is controlled at 50-60℃. Chitosan and concentrated sulfuric acid are added, and the temperature is controlled at 55-60℃. The reaction is kept at this temperature for 4-8 hours with stirring. The pH is adjusted to 7-7.5, and acetone is added to stop the reaction. The precipitate is taken, washed, and dried to obtain modified chitosan.

[0011] As a further embodiment of the present invention: the addition ratio of palmitic acid, anhydrous ethanol, chitosan, and concentrated sulfuric acid is 15-20g: 250-500mL: 10g: 1-3g.

[0012] As a further aspect of the present invention, the preparation method of modified nanoporous silica includes the following steps:

[0013] A1: Add nanoporous silica, ethanol, and deionized water to a reaction flask and mix them together. Add γ-aminopropyltriethoxysilane and reflux for 2-4 hours to obtain organic silica.

[0014] A2: Stearic acid and toluene are added to a reaction flask and dispersed evenly. Organic silica is added, and the temperature is controlled at 40-50℃. The reaction is kept at this temperature for 1-3 hours. After washing, filtering, and drying, modified nanoporous silica is obtained.

[0015] As a further aspect of the present invention: the addition ratio of nanoporous silica, ethanol, deionized water and γ-aminopropyltriethoxysilane in A1 is 10g:90-180mL:10-20mL:4-8g;

[0016] In A2, the addition ratio of stearic acid, toluene, and 10g is 3-5g: 100-200mL: organic silica.

[0017] As a further aspect of the present invention: the application rate of the waterproof and oil-resistant adhesive is 0.5-5 g / m³. 2 .

[0018] As a further aspect of the present invention: the solvent is a 1-2 wt% aqueous solution of acetic acid; the bio-based crosslinking agent is composed of citric acid and glycerol triglycidyl ether in a molar ratio of 1:0.8-1.

[0019] As a further embodiment of the present invention, the preparation method of the waterproof and oil-proof adhesive includes the following steps: adding modified chitosan and solvent into a reaction vessel and dispersing them evenly, stirring at a controlled temperature of 40-50℃ for 1-2 hours, adding carboxymethyl cellulose, nanocellulose, and modified nanoporous silica and dispersing them evenly, adding a bio-based crosslinking agent, controlling the temperature at 40-50℃ and stirring for 1-2 hours, adjusting the pH to 6.5-7, and obtaining the waterproof and oil-proof adhesive.

[0020] As a further aspect of the present invention: sizing is performed on one side or both sides of the base paper surface.

[0021] As a further aspect of the present invention, the method for preparing the base paper includes the following steps: grinding the pulp, forming sheets, pressing, and drying to obtain the base paper.

[0022] A high-barrier, waterproof, and oil-resistant paper roll is made by any of the above preparation methods.

[0023] The beneficial effects of this invention are:

[0024] This application uses carboxymethyl cellulose and modified chitosan as the base material for waterproof and oil-resistant adhesives. In this application, palmitic acid is used to organically modify chitosan, replacing the hydroxyl groups of chitosan with long-chain alkyl groups and introducing hydrophobic groups to obtain modified chitosan, thereby reducing the surface energy of the material.

[0025] This application adds nanocellulose and modified nanoporous silica as structural reinforcing components for waterproof and oil-resistant adhesives. Nanocellulose increases the elastic modulus of the coating; modified nanoporous silica fills the pores on the surface of the base paper and constructs a micro-nano rough structure. The modified nanoporous silica is obtained by modifying the mesoporous silica with aminosilane coupling agents and fatty acids based on nanoporous silica. The modified nanoporous silica acts as a rheology modifier and structural reinforcing agent, improving the leveling and reducing the flow resistance of the coating, while filling the pores on the surface of the base paper and improving the barrier properties of the material.

[0026] This application also utilizes a combination of citric acid and genipin as a crosslinking agent for the material, which enhances the density of the coating and reduces the polysaccharide content through a crosslinking reaction, while improving the water resistance and mechanical strength of the material.

[0027] This application involves coating the surface of base paper with a biomass coating material that is not only biodegradable but also acts as a barrier layer against oxygen, water, and oil, effectively reducing nutrient loss in food and extending its shelf life. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: The preparation method of modified nanoporous silica includes the following steps:

[0030] A1: 10g of nanoporous silica (pore size 5-10nm, specific surface area >800m²) 2 / g pore volume 1.2cm 3 90 mL of ethanol and 10 mL of deionized water were added to the reaction flask and mixed together. Then, 4 g of γ-aminopropyltriethoxysilane was added and the mixture was refluxed for 2 h to obtain organosilica.

[0031] A2: Add 3g of stearic acid and 100mL of toluene to a reaction flask and disperse evenly. Add 10g of organo-modified silica, control the temperature at 40℃, and keep the reaction at this temperature for 1h. Wash, filter, and dry to obtain modified nanoporous silica.

[0032] The preparation method of modified chitosan includes the following steps:

[0033] In a nitrogen atmosphere, 15g of palmitic acid and 250mL of anhydrous ethanol were added to a reaction flask. The temperature was controlled at 50℃. 10g of chitosan (90% deacetylation) and 1g of 98wt% concentrated sulfuric acid were added. The temperature was controlled at 55℃ and the reaction was kept at this temperature for 4 hours with stirring. The pH was adjusted to 7. Acetone was added to stop the reaction. The precipitate was washed and dried to obtain modified chitosan.

[0034] Example 2: The preparation method of modified nanoporous silica includes the following steps:

[0035] A1: 10g of nanoporous silica (pore size 5-10nm, specific surface area >800m²) 2 / g pore volume 1.2cm 3 150 mL of ethanol and 15 mL of deionized water were added to the reaction flask and mixed together. Then, 6 g of γ-aminopropyltriethoxysilane was added and the mixture was refluxed for 3 h to obtain organosilica.

[0036] A2: Add 4g of stearic acid and 150mL of toluene to a reaction flask and disperse evenly. Add 10g of organo-modified silica, control the temperature at 45℃, and keep the reaction at this temperature for 2 hours. Wash, filter, and dry to obtain modified nanoporous silica.

[0037] The preparation method of modified chitosan includes the following steps:

[0038] In a nitrogen atmosphere, 15g of palmitic acid and 300mL of anhydrous ethanol were added to a reaction flask. The temperature was controlled at 55℃. 10g of chitosan (90% degree of deacetylation) and 2g of concentrated sulfuric acid were added. The temperature was controlled at 60℃ and the reaction was kept at this temperature for 6 hours with stirring. The pH was adjusted to 7. Acetone was added to stop the reaction. The precipitate was taken, washed, and dried to obtain modified chitosan.

[0039] Example 3: The preparation method of modified nanoporous silica includes the following steps:

[0040] A1: 10g of nanoporous silica (pore size 5-10nm, specific surface area >800m²) 2 / g pore volume 1.2cm 3 180 mL of ethanol and 20 mL of deionized water were added to the reaction flask and mixed together. Then, 8 g of γ-aminopropyltriethoxysilane was added and the mixture was refluxed for 4 h to obtain organosilica.

[0041] A2: Add 5g of stearic acid and 200mL of toluene to a reaction flask and disperse evenly. Add 10g of organo-modified silica, control the temperature at 50℃, and keep the reaction at this temperature for 3 hours. Wash, filter, and dry to obtain modified nanoporous silica.

[0042] The preparation method of modified chitosan includes the following steps:

[0043] In a nitrogen atmosphere, 20g of palmitic acid and 500mL of anhydrous ethanol were added to a reaction flask. The temperature was controlled at 60℃. 10g of chitosan (90% deacetylation) and 3g of 98wt% concentrated sulfuric acid were added. The reaction was maintained at 60℃ with stirring for 8 hours. The pH was adjusted to 7.5. Acetone was added to stop the reaction. The precipitate was washed and dried to obtain modified chitosan.

[0044] Example 4: A method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper, comprising the following steps:

[0045] S1: 1.5g of the modified chitosan prepared in Example 1 and 92.97g of 1wt% acetic acid aqueous solution were added to the reaction vessel and dispersed evenly. The temperature was controlled at 40℃ and stirred for 2h. 4.5g of carboxymethyl cellulose (purchased from Shanghai Sinopharm Group), 0.5g of nanocellulose and 0.2g of the modified nanoporous silica prepared in Example 1 were added and dispersed evenly. 0.15g of citric acid and 0.18g of glycerol triglycidyl ether were added. The temperature was controlled at 50℃ and stirred for 1h. The pH was adjusted to 7 to obtain a waterproof and oil-resistant adhesive.

[0046] S2: Obtained by papermaking from base paper (softwood pulp beaten paper 25°SR); basis weight 50g / m³ 2 Apply waterproof and oil-resistant adhesive, with an application rate of 3.5g / m². 2 This yields high-barrier, waterproof, and oil-resistant paper wrappers.

[0047] Example 5: A method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper, comprising the following steps:

[0048] S1: 1.5g of the modified chitosan prepared in Example 2 and 92.97g of 1wt% acetic acid aqueous solution were added to the reaction vessel and dispersed evenly. The temperature was controlled at 40℃ and stirred for 2h. 4.5g of carboxymethyl cellulose (purchased from Shanghai Sinopharm Group), 0.5g of nanocellulose and 0.2g of the modified nanoporous silica prepared in Example 2 were added and dispersed evenly. 0.15g of citric acid and 0.18g of glycerol triglycidyl ether were added. The temperature was controlled at 50℃ and stirred for 1h. The pH was adjusted to 7 to obtain a waterproof and oil-resistant adhesive.

[0049] S2: Obtained by papermaking from base paper (softwood pulp beaten paper 25°SR); basis weight 50g / m³ 2 Apply waterproof and oil-resistant adhesive, with an application rate of 3.5g / m². 2 This yields high-barrier, waterproof, and oil-resistant paper wrappers.

[0050] Example 6: A method for preparing high-barrier, waterproof, and oil-resistant paper rolls, comprising the following steps:

[0051] S1: 1.5g of the modified chitosan prepared in Example 3 and 92.97g of 1wt% acetic acid aqueous solution were added to the reaction vessel and dispersed evenly. The temperature was controlled at 40℃ and stirred for 2h. 4.5g of carboxymethyl cellulose (purchased from Shanghai Sinopharm Group), 0.5g of nanocellulose and 0.2g of the modified nanoporous silica prepared in Example 3 were added and dispersed evenly. 0.15g of citric acid and 0.18g of glycerol triglycidyl ether were added. The temperature was controlled at 50℃ and stirred for 1h. The pH was adjusted to 7 to obtain a waterproof and oil-resistant adhesive.

[0052] S2: Obtained by papermaking from base paper (softwood pulp beaten paper 25°SR); basis weight 50g / m³ 2 Apply waterproof and oil-resistant adhesive, with an application rate of 3.5g / m². 2 This yields high-barrier, waterproof, and oil-resistant paper wrappers.

[0053] The preparation method of the modified nano-silica in Comparative Example 1 includes the following steps:

[0054] A1: Add 10g of nano-silica, 150mL of ethanol and 15mL of deionized water to a reaction flask and mix them together. Add 6g of γ-aminopropyltriethoxysilane and reflux for 3h to obtain organic silica.

[0055] A2: Add 4g of stearic acid and 150mL of toluene to a reaction flask and disperse evenly. Add 10g of organosilica, control the temperature at 45℃ and keep the reaction at this temperature for 2 hours. Wash, filter and dry to obtain modified nano-silica.

[0056] The preparation method of modified nanoporous silica in Comparative Example 2 includes the following steps:

[0057] 10g of nanoporous silica (pore size 5-10nm, specific surface area >800m²) was used. 2 / g pore volume 1.2cm 3 150 mL of ethanol and 15 mL of deionized water were added to a reaction flask and mixed together. Then, 6 g of γ-aminopropyltriethoxysilane was added, and the mixture was refluxed for 3 h to obtain modified nanoporous silica.

[0058] The preparation method of the modified nanoporous silica in Comparative Example 3 includes the following steps:

[0059] Add 4g of stearic acid and 150mL of toluene to a reaction flask and disperse evenly. Then add 10g of nanoporous silica (pore size 5-10nm, specific surface area >800m²). 2 / g pore volume 1.2cm 3 / g), controlled at 45℃ and kept at that temperature for 2 hours, then washed, filtered and dried to obtain modified nanoporous silica.

[0060] Comparative Example 4 is a method for preparing a high-barrier, waterproof, and oil-proof dinner wrapping paper. Compared with Example 5, only the modified chitosan prepared in Example 2 was replaced with an equal amount of chitosan in Example 5. The other components and preparation methods are completely the same as in Example 5.

[0061] Comparative Example 5 is a method for preparing a high-barrier, waterproof, and oil-proof dinner wrapping paper. Compared with Example 5, the only difference is that the modified nanoporous silica prepared in Example 2 is replaced in equal amounts with the modified nano silica prepared in Comparative Example 1. The other components and preparation methods are completely consistent with Example 5.

[0062] Comparative Example 6 describes a method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper. Compared with Example 5, the only difference is that the modified nanoporous silica prepared in Example 2, which was added in Example 5, is replaced in equal amounts with the modified nanoporous silica prepared in Comparative Example 2. The other components and preparation methods are completely consistent with Example 5.

[0063] Comparative Example 7 is a method for preparing a high-barrier, waterproof, and oil-proof dinner wrapping paper. Compared with Example 5, the only difference is that the modified nanoporous silica prepared in Example 2, which was added in Example 5, is replaced in equal amounts with the modified nanoporous silica prepared in Comparative Example 3. The other components and preparation methods are completely consistent with Example 5.

[0064] Performance testing

[0065] (1) Oil resistance rating: According to the TAPPI559cm-12 standard, the Kit Rating test solution was prepared. The components of the test solution are shown in Table 1. The high bond energy test solution was dripped onto the paper sample surface from 13mm away. After 15s, the test solution was wiped off with a degreased cotton ball. The color of the paper sample surface was observed. If the color changed, the next level test was performed until the paper sample surface no longer changed. The corresponding level at this time is the oil resistance rating of the paper sample. The test results are shown in Table 2.

[0066] Table 1: Composition of Kit Rating Test Solution

[0067] Castor oil (g) Toluene (mL) n-Heptane (mL) 1 969 0 0 2 872.1 50 50 3 775.2 100 100 4 678.3 150 150 5 581.4 200 200 6 484.5 250 250 7 387.6 300 300 8 290.7 350 350 9 193.8 400 400 10 96.9 450 450 11 0 500 500 12 0 450 550

[0068] (2) Water resistance: The Cobb test was conducted according to GB / T 1540-2002 "Determination of water absorption of paper and paperboard - Cobb method". The Cobb absorbency tester was used to determine the Cobb value of the paper. The test surface of the sample was in contact with water for 60s and the increase in mass per unit area was measured. The result is expressed as Cobb60. The test results are shown in Table 2.

[0069] (3) Water contact angle: The wettability of paper was measured using a contact angle analyzer, and the contact angle WCA between water and the paper surface was recorded. The test results are shown in Table 2.

[0070] (4) Folding endurance: The test was conducted according to GB / T 2679.5-1995 "Determination of folding endurance of paper and paperboard". The test results are shown in Table 2.

[0071] Table 2: Performance Test Data Statistics of Examples 4-6 and Comparative Examples 4-7

[0072]

[0073] As shown in Table 2, this application achieves high barrier waterproof and oil-proof effects through the synergistic effect of hydrophobic modification and nanocomposite, effectively reducing the amount of polysaccharide in the coating, while solving the flow resistance, and effectively improving the oil-proof wettability and ease of coating of the material.

[0074] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper, characterized in that, The process includes the following steps: coating the base paper with a waterproof and oil-resistant adhesive to obtain a high-barrier, waterproof, and oil-resistant dinner wrapping paper; The waterproof and oil-resistant adhesive comprises the following raw materials by weight percentage: 1-2% modified chitosan, 4-5% carboxymethyl cellulose, 0.3-0.5% nanocellulose, 0.15-0.25% modified nano-mesoporous silica, 0.3-0.42% bio-based crosslinking agent, and the balance being solvent, with the sum of the raw material weight percentages being 100%.

2. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The preparation method of the modified chitosan includes the following steps: In a nitrogen atmosphere, palmitic acid and anhydrous ethanol are added to a reaction flask, and the temperature is controlled at 50-60℃. Chitosan and concentrated sulfuric acid are added, and the temperature is controlled at 55-60℃. The reaction is kept at this temperature for 4-8 hours with stirring. The pH is adjusted to 7-7.5, and acetone is added to stop the reaction. The precipitate is taken, washed, and dried to obtain modified chitosan.

3. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The addition ratio of palmitic acid, anhydrous ethanol, chitosan, and concentrated sulfuric acid is 15-20g: 250-500mL: 10g: 1-3g.

4. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The method for preparing the modified nanoporous silica includes the following steps: A1: Add nanoporous silica, ethanol, and deionized water to a reaction flask and mix them together. Add γ-aminopropyltriethoxysilane and reflux for 2-4 hours to obtain organic silica. A2: Stearic acid and toluene are added to a reaction flask and dispersed evenly. Organic silica is added, and the temperature is controlled at 40-50℃. The reaction is kept at this temperature for 1-3 hours. After washing, filtering, and drying, modified nanoporous silica is obtained.

5. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The addition ratio of nanoporous silica, ethanol, deionized water and γ-aminopropyltriethoxysilane in A1 is 10g: 90-180mL: 10-20mL: 4-8g; In A2, the addition ratio of stearic acid, toluene, and 10g is 3-5g: 100-200mL: organic silica.

6. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The application rate of the waterproof and oil-resistant adhesive is 0.5-5 g / m³. 2 .

7. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The solvent is a 1-2 wt% aqueous solution of acetic acid; the bio-based crosslinking agent is composed of citric acid and glycerol triglycidyl ether in a molar ratio of 1:0.8-1.

8. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The sizing process involves sizing one or both sides of the base paper surface.

9. The method for preparing a high-barrier, waterproof, and oil-resistant dinner wrapping paper according to claim 1, characterized in that, The method for preparing the base paper includes the following steps: grinding the pulp, forming sheets, pressing, and drying to obtain the base paper.

10. A high-barrier, waterproof, and oil-resistant paper wrapper, characterized in that... It is prepared by the method described in any one of claims 1-9.

Images