Glue for visual palm sealing of thermal shrinkage film label and preparation method of glue

Abstract

The invention discloses glue for visual palm sealing of a heat shrink film label and a preparation method, the glue comprises the following components by mass percentage: 52-68% of 1, 4-dioxane, 25-40% of 1, 3-dioxolane, 4-8% of a photosensitive discoloration solution, 1-3% of a curing agent, 1-3% of a curing agent, and 1-3% of a curing agent. The photochromic solution is prepared from the following components in percentage by mass: 17%-24% of inorganic ultraviolet fluorescent powder, 44%-51% of binding phase resin and 30%-35% of a solvent, and the preparation method of the glue comprises the following steps: adding part of the inorganic ultraviolet fluorescent powder into the binding phase resin in batches, stirring to form a photochromic dispersoid, and drying the photochromic dispersoid to obtain the photochromic glue. Mixing the rest of the inorganic ultraviolet fluorescent powder, the photosensitive discoloration dispersoid and the solvent, and stirring to obtain a photosensitive discoloration solution; the method comprises the following steps: mixing 1, 4-dioxane and 1, 3-dioxolane, uniformly stirring to form palm-sealing glue, adding a photochromic solution into the palm-sealing glue, stirring to form glue, and the glue can develop color under ultraviolet light, can be normally bonded when being used for palm-sealing of a heat shrinkage film label, and is not easy to wrinkle and warp.

Description

Technical Field

[0001] The invention belongs to the technical field of glue, and in particular relates to glue for visualized closure of heat shrinkable film labels and a preparation method thereof. Background Art

[0002] At present, the printed labels for beverage bottle packaging often use polyvinyl chloride (PVC) and modified polyethylene terephthalate (PETG) plastic films with heat shrink properties as the base material. Because PVC is prone to produce highly toxic dioxins during recycling and has environmental defects, it is gradually banned from use in food and beverage packaging. PETG is a non-crystalline copolymer polyester. During its production process, a certain amount of ethylene glycol is replaced by 1,4-cyclohexane dimethanol (CHDM, 1,4-cyclohexanedimethanol comonomer), which can prevent crystallization and improve processing and transparency. Using PETG heat shrinkable material as a film label is not only non-toxic, odorless, environmentally friendly, high-strength, high heat shrinkage rate, and beautiful packaging effect, but also has good optical properties and mechanical ductility.

[0003] Before the film label is affixed to the bottle body, it is necessary to fold and bond the two sides of a certain width of film (the glued side and the bonded side) to form a sleeve-type label. This process is called hand-jointing. The common hand-jointing process is to evenly apply glue to the edge of the film through a hand-jointing machine, and then fold the film in a certain direction and bond it to the other side to form a sleeve-type label.

[0004] In the existing hand-jointing process, PETG hand-jointing glue is the key material to ensure that the large and small edges of the label are tightly combined. However, the existing hand-jointing glue only has basic adhesion function, and the position and amount of glue cannot be observed in real time (see Figure 1 ), in the production process, quality problems such as intermittent lack of glue, glue overflow / overflow and bubbles are prone to occur, which reduces the qualified rate of label products and causes quality problems in label application such as label jamming and flying labels. Summary of the invention

[0005] The purpose of the present invention is to solve at least one problem in the prior art and to provide a glue for the visualized closure of heat shrinkable film labels and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the present invention proposes a glue for the visualized palm-joining of a heat shrinkable film label, wherein the glue is composed of the following components in percentage by mass: 52% to 68% of 1,4-dioxane, 25% to 40% of 1,3-dioxolane, and 4% to 8% of a photochromic solution, wherein the photochromic solution is composed of the following components in percentage by mass: 17% to 24% of an inorganic ultraviolet fluorescent powder, 44% to 51% of a bonding phase resin, and 30% to 35% of a solvent, and the glue is coated on the palm-joining surface of the heat shrinkable film label, and after the heat shrinkable film label is palm-joined, the glue is colored under ultraviolet light.

[0007] Preferably, the inorganic ultraviolet phosphor has a particle size of 5 μm to 10 μm, and the particles are spherical. The setting of the particle size and particle shape is conducive to improving the dispersibility of the inorganic ultraviolet phosphor in the binding phase resin. The inorganic ultraviolet phosphor with smaller particles is easy to agglomerate, and the inorganic ultraviolet phosphor with large particles is not easy to disperse. The inorganic ultraviolet phosphor is white or nearly transparent under a visible light source, and will not affect the appearance of the label after the palm is closed.

[0008] Preferably, the wavelength of the ultraviolet lamp is 254nm to 365nm.

[0009] Preferably, the solvent is ethyl acetate or n-propyl acetate.

[0010] Preferably, the binder phase resin is polyurethane resin or acrylic resin.

[0011] Preferably, the heat shrinkable film label is a PETG heat shrinkable film label, and the transverse shrinkage rate of the PETG heat shrinkable film label is 55% to 70%.

[0012] The present invention also proposes a method for preparing the above-mentioned glue, comprising the following steps:

[0013] Preparation of photochromic solution: adding part of inorganic ultraviolet phosphor into the binder phase resin in batches, stirring to form a photochromic dispersion, mixing the remaining inorganic ultraviolet phosphor, the photochromic dispersion and the solvent, stirring evenly, to obtain a photochromic solution;

[0014] Preparation of glue: Mix 1,4-dioxane and 1,3-dioxolane, stir evenly to form gash-shaped glue, then add the above-mentioned photochromic solution into the gash-shaped glue, stir evenly to form glue that shows color under ultraviolet light.

[0015] Preferably, in the preparation step of the photochromic solution, stirring is carried out at a rotation speed of 450 rpm to 550 rpm and a temperature of 24° C. to 27° C., and the stirring time is 14 min to 20 min.

[0016] Preferably, in the preparation step of the glue, stirring is carried out at a rotation speed of 250 rpm to 350 rpm and a temperature of 24° C. to 27° C., and the stirring time is 4 min to 15 min.

[0017] The beneficial effects of the present invention are as follows: the glue of the present invention adopts the optimal compounding, so that the glue can be normally bonded when used for heat shrink film labels and is not prone to wrinkles and warping; the photochromic solution is added to the glue, and the photochromic solution adopts the optimal compounding to ensure that the inorganic ultraviolet fluorescent powder is evenly dispersed in the adhesive phase resin, avoiding the weakening of light sensitivity caused by low content, and the inorganic ultraviolet fluorescent powder in the glue can be colored under ultraviolet light, so that the position of the glue and the spread of the glue can be observed in real time during the process of label closing, avoiding excessive dissolution of the film due to excessive glue, resulting in wrinkles and adhesion at the closing position, or insufficient glue amount, resulting in the label. The risk of loose connection or failure at the joint can be eliminated, and quality abnormalities such as glue bubbles, internal and external glue overflow can be avoided in time. The visualization of the joint glue is conducive to discovering problems in the production process and adjusting the joint and spraying process in time; the binding phase resin in the photochromic solution can maintain the fluidity and stability of the inorganic ultraviolet phosphor, and improve the adhesion of the inorganic ultraviolet phosphor on the label film; the solvent in the photochromic solution is preferably a quick-drying solvent, which is convenient for controlling the drying speed of the photochromic solution, ensuring the effective implementation of high-speed operation, promoting the dispersion of the inorganic ultraviolet phosphor in the binding phase resin, and ensuring the uniformity and stability of the photochromic solution.

[0018] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the coating effect of the existing glue on the label palm position under visible light and ultraviolet light.

[0020] Figure 2 It is a schematic diagram of the coating effect of the glue of an embodiment of the present invention on the label palm-jointed position under visible light and ultraviolet light.

[0021] Figure 3 It is a schematic diagram of glue breaking and glue overflow after the glue of the embodiment of the present invention is applied to the label palm position under visible light and ultraviolet light.

[0022] Figure 4 This is a schematic diagram of film warping after coating the label's palm position with poorly formulated glue under visible light and ultraviolet light.

[0023] Figures 1 to 4 Figures a and b are schematic diagrams under visible light, and Figures b are schematic diagrams under ultraviolet light. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments.

[0025] The present invention is described in detail below in conjunction with the accompanying drawings.

[0026] Example 1

[0027] The present embodiment provides a glue for the visualized palm-jointing of heat shrinkable film labels, the glue being composed of the following components in percentage by mass: 53.3% of 1,4-dioxane, 40% of 1,3-dioxolane, and 6.7% of a photochromic solution, and the photochromic solution being composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of ethyl acetate.

[0028] The preparation method of the glue in this embodiment comprises the following steps:

[0029] S01. Preparation of photochromic solution: Weigh 1g of inorganic ultraviolet phosphor, 2g of polyurethane resin, and 1.5g of ethyl acetate, divide 1g of inorganic ultraviolet phosphor into 4 equal parts, add three parts of inorganic ultraviolet phosphor into polyurethane resin three times, stir for 20min at a speed of 500 rpm and a temperature of 25°C to form a photochromic dispersion, mix the remaining part of inorganic ultraviolet phosphor, photochromic dispersion, and ethyl acetate, continue stirring for 20min, and mix to obtain a photochromic solution;

[0030] S02. Preparation of glue: Weigh 4g of 1,4-dioxane and 3g of 1,3-dioxolane, add them into a stirring container, stir at a speed of 300 rpm and a temperature of 25°C for 5 minutes, and form a glue after stirring evenly. Weigh 0.5g of the above-mentioned photochromic solution and add it into the glue, stir at a speed of 300 rpm and a temperature of 25°C for 10 minutes, and mix evenly to form a glue that shows color under ultraviolet light.

[0031] Example 2

[0032] The present embodiment provides a glue for the visualized palm closing of heat shrinkable film labels, the glue is composed of the following components in percentage by mass: 60% of 1,4-dioxane, 35% of 1,3-dioxolane, and 5% of a photochromic solution, and the photochromic solution is composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of n-propyl ester.

[0033] The preparation method of the glue in this embodiment comprises the following steps:

[0034] S01. Preparation of photochromic solution: Weigh 1g of inorganic ultraviolet phosphor, 2g of polyurethane resin, and 1.5g of n-propyl acetate, divide 1g of inorganic ultraviolet phosphor into 4 equal parts, add three parts of inorganic ultraviolet phosphor into polyurethane resin three times, stir for 15min at a speed of 550 rpm and a temperature of 25°C to form a photochromic dispersion, mix the remaining part of inorganic ultraviolet phosphor, photochromic dispersion, and n-propyl acetate, continue stirring for 15min, and mix to obtain a photochromic solution;

[0035] S02. Preparation of glue: Weigh 12g of 1,4-dioxane and 7g of 1,3-dioxolane into a stirring container, stir at a speed of 350 rpm and a temperature of 25°C for 8 minutes, and form a glue after stirring evenly. Weigh 1g of the above-mentioned photochromic solution and add it to the glue, stir at a speed of 350 rpm and a temperature of 25°C for 15 minutes, and mix evenly to form a glue that shows color under ultraviolet light.

[0036] Example 3

[0037] The present embodiment provides a glue for the visualized palm-jointing of heat shrinkable film labels, the glue being composed of the following components in percentage by mass: 60% of 1,4-dioxane, 32% of 1,3-dioxolane, and 8% of a photochromic solution, and the photochromic solution being composed of the following components in percentage by mass: 19.4% of an inorganic ultraviolet fluorescent powder, 48.4% of a polyurethane resin, and 32.2% of ethyl acetate.

[0038] The preparation method of the glue in this embodiment comprises the following steps:

[0039] S01. Preparation of photochromic solution: Weigh 0.6g of inorganic ultraviolet phosphor, 1.5g of polyurethane resin, and 1g of ethyl acetate, divide 0.6g of inorganic ultraviolet phosphor into 4 equal parts, add three parts of inorganic ultraviolet phosphor into polyurethane resin three times, stir for 15min at a speed of 600 rpm and a temperature of 26°C to form a photochromic dispersion, mix the remaining part of inorganic ultraviolet phosphor, photochromic dispersion, and ethyl acetate, continue stirring for 15min, and obtain a photochromic solution after mixing;

[0040] S02. Preparation of glue: Weigh 3.75g of 1,4-dioxane and 2g of 1,3-dioxolane, add them into a stirring container, stir at a speed of 300 rpm and a temperature of 26°C for 10 minutes, and form a glue after stirring evenly. Weigh 0.5g of the above-mentioned photochromic solution and add it into the glue, stir at a speed of 300 rpm and a temperature of 26°C for 15 minutes, and form a glue that shows color under ultraviolet light after mixing evenly.

[0041] Example 4

[0042] The present embodiment provides a glue for the visualized closing of heat shrink film labels, the glue consisting of the following components in percentage by mass: 52% of 1,4-dioxane, 40% of 1,3-dioxolane, and 8% of a photochromic solution, the photochromic solution consisting of the following components in percentage by mass: 24% of an inorganic ultraviolet fluorescent powder, 46% of an acrylic resin, and 30% of ethyl acetate.

[0043] The preparation method of the glue in this embodiment comprises the following steps:

[0044] S01. Preparation of photochromic solution: Weigh 0.6g of inorganic ultraviolet phosphor, 1.15g of acrylic resin, and 0.75g of ethyl acetate, and divide 0.6g of inorganic ultraviolet phosphor into 4 equal parts, wherein three parts of inorganic ultraviolet phosphor are added into polyurethane resin three times, and stirred for 20min at a speed of 450 rpm and a temperature of 25°C to form a photochromic dispersion, and the remaining part of inorganic ultraviolet phosphor, photochromic dispersion, and ethyl acetate are mixed with each other, and stirring is continued for 20min to obtain a photochromic solution after mixing;

[0045] S02. Preparation of glue: Weigh 5.2g of 1,4-dioxane and 4g of 1,3-dioxolane into a stirring container, stir at a speed of 350 rpm and a temperature of 25°C for 4 minutes, and form a glue after stirring evenly. Weigh 0.8g of the above-mentioned photochromic solution and add it to the glue, stir at a speed of 350 rpm and a temperature of 25°C for 6 minutes, and form a glue that shows color under ultraviolet light after mixing evenly.

[0046] Comparative Example 1

[0047] This comparative example provides a glue, which is composed of the following components in percentage by mass: 51.9% of 1,4-dioxane, 39% of 1,3-dioxolane, and 9.1% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of ethyl acetate.

[0048] Comparative Example 2

[0049] This comparative example provides a glue, which is composed of the following components in percentage by mass: 54.8% of 1,4-dioxane, 41.1% of 1,3-dioxolane, and 4.1% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of ethyl acetate.

[0050] Comparative Example 3

[0051] This comparative example provides a glue, which is composed of the following components in percentage by mass: 54.5% of 1,4-dioxane, 36.4% of 1,3-dioxolane, and 9.1% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of ethyl acetate.

[0052] Comparative Example 4

[0053] This comparative example provides a glue, which is composed of the following components in percentage by mass: 66.7% of 1,4-dioxane, 25% of 1,3-dioxolane, and 8.3% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 19.4% of an inorganic ultraviolet fluorescent powder, 48.4% of a polyurethane resin, and 32.2% of ethyl acetate.

[0054] Comparative Example 5

[0055] This comparative example provides a glue, which is composed of the following components in percentage by mass: 53.3% of 1,4-dioxane, 40% of 1,3-dioxolane, and 6.7% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 22.2% of an inorganic ultraviolet fluorescent powder, 44.4% of a polyurethane resin, and 33.4% of n-propyl ester.

[0056] Comparative Example 6

[0057] This comparative example provides a photochromic solution, which is composed of the following components in percentage by mass: 14.6% of inorganic ultraviolet fluorescent powder, 48.8% of polyurethane resin, and 36.6% of ethyl acetate.

[0058] Comparative Example 7

[0059] This comparative example provides a photochromic solution, which is composed of the following components in percentage by mass: 22.2% of photochromic powder, 44.4% of polyurethane resin, and 33.4% of ethyl acetate.

[0060] Comparative Example 8

[0061] This comparative example provides a photochromic solution, which is composed of the following components in percentage by mass: 10.7% of inorganic ultraviolet fluorescent powder, 53.6% of polyurethane resin, and 35.7% of ethyl acetate.

[0062] In the above embodiments and comparative examples, 1,3-dioxolane and 1,4-dioxane were purchased from Shanghai Senbok New Materials Co., Ltd., polyurethane resin was purchased from Shanghai DIC Ink Co., Ltd., solvent was purchased from Hangzhou Hengyu Packaging Materials Co., Ltd., photosensitive color-changing powder was purchased from Shenzhen Huancai Color-changing Technology Co., Ltd., and inorganic ultraviolet phosphor was purchased from Shenzhen Dongfang Color-changing Technology Co., Ltd.

[0063] 1. Performance test of photochromic solution

[0064] Take equal amounts of the photochromic solutions in Examples 1 to 3 and the photochromic solutions in Comparative Examples 6 to 8. The preparation methods of the photochromic solutions are the same. The uniformity and light-changing brightness of the photochromic solutions are tested under the same test conditions. The specific test results are shown in Table 1 below.

[0065] Table 1 Solution uniformity and light-changing brightness test results of photochromic solutions with different component ratios

[0066]

[0067]

[0068] In Table 1, through the performance comparison results of the photochromic solution of Example 7 and Example 1, it can be seen that compared with the photochromic powder, the inorganic ultraviolet phosphor is more sensitive to the ultraviolet wavelength and has better compatibility with the polyurethane resin; through the performance comparison results of the photochromic solution of Example 6 and the photochromic solution of Example 1, and the performance comparison results of the photochromic solution of Example 8 and the photochromic solution of Example 3, it can be seen that the composition ratio of the inorganic ultraviolet phosphor and the polyurethane resin in the photochromic solution will have a great influence on the uniformity of the solution and the light-changing brightness.

[0069] This shows that the unique compounding ratio of the present invention can ensure that the inorganic ultraviolet phosphor is evenly dispersed in the resin, avoid the weakening of light perception caused by low content, and can clearly show color under ultraviolet light.

[0070] 2. Test on the effect of glue on heat shrink film labels

[0071] Take equal amounts of the glue of Example 1 and the glue of Comparative Examples 1 to 5, and use them in the same closing machine, respectively. When the closing machine (running speed is 300-400 m / min) is working, the glue of Example 1 and Comparative Examples 1 to 5 are evenly coated on the closing surface of the PETG heat shrink label through a 150 μm diameter glue spraying pinhole, and the PETG heat shrink label is closed by a pressure roller. The closing effect of each glue after being applied to the PETG heat shrink label is observed. The specific test results are shown in Table 2. Figures 2 to 4 shown.

[0072] Table 2 Test results of different glues for palm-fitting effect

[0073]

[0074] It can be seen from Table 2 that after the glue with the ratio of the present invention is applied to the palm-joining position of the PETG heat shrink label, the label film can be bonded normally without wrinkling or warping. After the glue with the ratios of Comparative Examples 1 to 5 is applied to the palm-joining position of the PETG heat shrink label, the label film cannot be bonded and wrinkles and warping occur.

[0075] This shows that only when 1,4-dioxane, 1,3-dioxolane and the photochromic solution in the glue of the present invention are compounded in a specific ratio can the label film be normally bonded without wrinkling or warping after the glue is applied to the palm position of the PETG heat shrink label.

[0076] The use of quick-drying photochromic solution in the glue can make the glue dry quickly on the PETG film to avoid glue overflow. The specific proportion of the photochromic solution in the glue can improve the flatness of the film joint area. If the content of the photochromic solution is too high, the corrosion effect of the glue will be weakened, and poor bonding will occur at the film joint; on the contrary, if the content is too low, it will easily cause a high corrosion effect, resulting in film wrinkles and even erosion of the label pattern.

[0077] Through the above tests, it can be seen that after the 1,4-dioxane, 1,3-dioxolane and photochromic solution in the glue are compounded with the component ratio of the present invention, not only has a good ultraviolet light sensitivity effect, but also maximizes the bonding strength of the glue. Figures 2 to 4 In the actual production process, the distribution of glue at the label joint under ultraviolet light is helpful to prevent quality problems such as no glue, internal and external glue overflow, etc. When there is no glue or glue overflow at the joint, the gluing process of the joint machine can be adjusted in time to ensure the quality of the label joint.

[0078] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. A glue for heat shrink film label visual jointing, It is characterized in that The glue is composed of the following components in percentage by mass: 52% to 68% of 1,4-dioxane, 25% to 40% of 1,3-dioxolane, and 4% to 8% of a photochromic solution. The photochromic solution is composed of the following components in percentage by mass: 17% to 24% of an inorganic ultraviolet fluorescent powder, 44% to 51% of a bonding phase resin, and 30% to 35% of a solvent. The glue is coated on the surface of the heat shrink film label, and after the heat shrink film label is closed, the glue develops color under ultraviolet light.

2. The glue for heat shrink film label visual closing as claimed in claim 1, Features: The particle size of the inorganic ultraviolet phosphor is 5 μm to 10 μm.

3. The glue for heat shrink film label visual closing as claimed in claim 1, Features: The wavelength of the ultraviolet lamp is 254nm-365nm.

4. The glue for heat shrink film label visual closing as claimed in claim 1, Features: The solvent is ethyl acetate or n-propyl acetate.

5. The glue for heat shrink film label visual closing as claimed in claim 1, Features: The bonding phase resin is polyurethane resin or acrylic resin.

6. The glue for heat shrink film label visual closing as claimed in claim 1, Features: The heat shrinkable film label is a PETG heat shrinkable film label, and the transverse shrinkage rate of the PETG heat shrinkable film label is 55% to 70%.

7. A method for preparing glue for heat shrink film label visual closure, Features: It includes the following steps: Preparation of photochromic solution: adding part of inorganic ultraviolet phosphor into the binder phase resin in batches, stirring to form a photochromic dispersion, mixing the remaining inorganic ultraviolet phosphor, the photochromic dispersion and the solvent, stirring evenly, to obtain a photochromic solution; Preparation of glue: Mix 1,4-dioxane and 1,3-dioxolane, stir evenly to form gash-shaped glue, then add the above-mentioned photochromic solution into the gash-shaped glue, stir evenly to form glue that shows color under ultraviolet light.

8. The method for preparing the glue for the heat shrink film label visual closing as claimed in claim 7, Features: In the preparation steps of the photochromic solution, stirring is performed at a rotation speed of 450 to 550 rpm and a temperature of 24° C. to 27° C., and the stirring time is 14 to 20 minutes.

9. The method for preparing the glue for the heat shrink film label visual closing as claimed in claim 7, Features: In the preparation steps of the glue, stirring is carried out at a rotation speed of 250 rpm to 350 rpm and a temperature of 24° C. to 27° C., and the stirring time is 4 min to 15 min.

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