A wear-resistant heat-sensitive color developing protective layer and a preparation method and application thereof

Abstract

The present application relates to a kind of wear-resistant heat-sensitive color development protective layer and its preparation method and application, belong to the technical field of slurry or paper pulp composition.The wear-resistant heat-sensitive color development protective layer of the present application includes mutually adhered mixed gelatin layer and pigskin gelatin layer;The mixed gelatin layer includes fish skin gelatin, pigskin gelatin and glycerol, and the pigskin gelatin layer includes pigskin gelatin and glycerol.The wear-resistant heat-sensitive color development protective layer not only has excellent wear resistance, but also has high adhesion, can be firmly attached to the surface of heat-sensitive paper, thereby significantly improving its anti-friction performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulp or paper pulp composition, and particularly relates to a wear-resistant thermal sensitive protective layer and a preparation method and application thereof. BACKGROUND

[0002] The thermal sensitive paper is generally composed of a base paper and a coating layer (the coating layer can be two or three layers, including a pre-coating layer, a thermal sensitive layer and a protective layer), wherein the base paper is generally a common paper base with high smoothness, heat preservation, flatness, no impurities, no holes and good tensile strength; the pre-coating layer is to prevent heat conduction to the inside of the paper and to ensure that the heat can be effectively intercepted between the protective layer and the pre-coating layer, thereby providing temperature protection for the reaction of the thermal sensitive layer color developer and the leuco dye; the thermal sensitive layer generally includes leuco fuel, sensitizer, color developer and adhesive and other components, and can produce color under the heating action of the thermal sensitive print head; the protective layer can enhance the waterproof, oil-proof or scratch-resistant performance of the thermal sensitive paper. However, it is found in the actual application process that although the surface of the thermal sensitive paper is provided with the protective layer, the information of the graphics or bar code cannot be recognized due to the poor scratch-resistant performance of the thermal sensitive paper during long-term storage or use. In view of the problem of poor scratch-resistant performance of the thermal sensitive paper, the prior art (CN106149465A) discloses a scratch-resistant thermal sensitive paper, which solves the problem by setting a scratch-resistant layer composed of fillers, petroleum refining products and adhesives between the thermal sensitive layer and the protective layer of the thermal sensitive paper; although the method can improve the scratch-resistant performance of the thermal sensitive paper, the improvement degree is limited. SUMMARY

[0003] The present application aims to overcome the deficiencies of the prior art and provide a wear-resistant thermal sensitive color developing protective layer and a preparation method and application thereof.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a wear-resistant thermal sensitive color developing protective layer, which comprises a mixed gelatin layer and a pigskin gelatin layer adhered to each other; the mixed gelatin layer comprises fish skin gelatin, pigskin gelatin and glycerol, and the pigskin gelatin layer comprises pigskin gelatin and glycerol.

[0006] The wear-resistant thermal sensitive color developing protective layer with a double-layer structure (Janus structure) is formed by combining the mixed gelatin layer and the pigskin gelatin layer, the pigskin gelatin layer mainly composed of pigskin gelatin and glycerol is used as a wear-resistant layer to enhance the anti-friction performance, and the mixed gelatin layer with high adhesion can firmly adhere the wear-resistant layer to the surface of the thermal sensitive layer of the thermal sensitive paper, and the glycerol can make the mixed gelatin layer and the pigskin gelatin layer both have good flexibility, thereby making the wear-resistant thermal sensitive color developing protective layer not easy to fall off or peel off during use, and thus excellent long-term anti-friction performance is given to the thermal sensitive paper.

[0007] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the mass ratio of fish skin gelatin, pigskin gelatin and glycerol in the mixed gelatin layer is 10:(2-8):(1-10). Alternatively, the fish skin gelatin in the mixed gelatin layer can be specifically 10 parts, the pigskin gelatin can be specifically 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, and the glycerol can be specifically 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts.

[0008] It is found that by adjusting the mass ratio of fish skin gelatin, pigskin gelatin and glycerol, the mechanical strength of the mixed gelatin layer can be controlled to effectively prevent it from being damaged in actual application. Moreover, when the mass ratio of fish skin gelatin, pigskin gelatin and glycerol is within the above range, the mixed gelatin layer not only has high adhesion, but also has good mechanical strength and flexibility.

[0009] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the mass ratio of pigskin gelatin and glycerol in the pigskin gelatin layer is 10:(0.5-1.5). Alternatively, the mass ratio of pigskin gelatin and glycerol in the pigskin gelatin layer can be specifically 10:0.6, 10:0.8, 10:1, 10:1.2, 10:1.4. It is found that when the mass ratio of pigskin gelatin and glycerol is within the above range, the mechanical strength and flexibility of the pigskin gelatin layer can be better balanced, thereby giving it long-term anti-friction performance.

[0010] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the average thickness of the mixed gelatin layer is 3-5 μm. Alternatively, the average thickness of the mixed gelatin layer can be specifically 3.5 μm, 4 μm, 4.5 μm.

[0011] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the average thickness of the pigskin gelatin layer is 5-10 μm. Alternatively, the average thickness of the pigskin gelatin layer can be specifically 6 μm, 7 μm, 8 μm, 9 μm.

[0012] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the fish skin gelatin has a gel strength of 200-240 g bloom; and / or, the pigskin gelatin has a gel strength of 260-300 g bloom. Alternatively, the fish skin gelatin can have a gel strength of 210 g bloom, 220 g bloom, 230 g bloom; and the pigskin gelatin can have a gel strength of 270 g bloom, 280 g bloom, 290 g bloom.

[0013] In a second aspect, the present application provides a preparation method of the wear-resistant heat-sensitive color developing protective layer, comprising the following steps:

[0014] The fish skin gelatin-based solution is first coated on the surface of the carrier, and then the pigskin gelatin-based film is attached to the surface of the fish skin gelatin-based solution, and dried to obtain the wear-resistant heat-sensitive color developing protective layer.

[0015] The fish skin gelatin-based solution comprises fish skin gelatin, pigskin gelatin, glycerol and water, and the mass fraction of the fish skin gelatin in the fish skin gelatin-based solution is 5% to 30%.

[0016] The pigskin gelatin-based film is obtained by drying a pigskin gelatin-based solution, and the pigskin gelatin-based solution comprises pigskin gelatin, glycerol and water, and the mass fraction of the pigskin gelatin in the pigskin gelatin-based solution is 20% to 40%.

[0017] Optionally, the mass fraction of the fish skin gelatin in the fish skin gelatin-based solution can be 6%, 8%, 10%, 12%, 15%, 20%, 25%, preferably 8% to 12%, and more preferably 10%; and the mass fraction of the pigskin gelatin in the pigskin gelatin-based solution can be 21%, 23%, 25%, 27%, 30%, 33%, 35%, 38%, preferably 25% to 35%, and more preferably 30%.

[0018] As a preferred embodiment of the wear-resistant heat-sensitive color developing protective layer, the fish skin gelatin-based solution is prepared by the following method: the fish skin gelatin and the pigskin gelatin are soaked in water for 20 to 90 minutes to swell, then stirred at 45 to 60°C for 10 to 30 minutes, and then glycerol is added and mixed uniformly to obtain the fish skin gelatin-based solution.

[0019] And / or, the pigskin gelatin-based solution is prepared by the following method: the pigskin gelatin is soaked in water for 20 to 90 minutes to swell, then stirred at 45 to 60°C for 10 to 30 minutes, and then glycerol is added and mixed uniformly to obtain the fish skin gelatin-based solution.

[0020] Optionally, the swelling time in the above preparation method can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, and preferably 60 minutes; the stirring speed is 300 to 600 rpm, and the stirring time after adding glycerol can be 10 to 60 minutes.

[0021] In a third aspect, the present application provides the use of the wear-resistant heat-sensitive color developing protective layer in the preparation of heat-sensitive paper.

[0022] Fourthly, the present invention provides a thermal paper, comprising thermal paper base paper, thermal color developing coating and protective layer, wherein the protective layer is the aforementioned wear-resistant thermal color developing protective layer, and the mixed gelatin layer in the wear-resistant thermal color developing protective layer is in contact with the thermal color developing coating in the thermal paper.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention combines a mixed gelatin layer and a pigskin gelatin layer to form a double-layered, wear-resistant, heat-sensitive color-developing protective layer. The pigskin gelatin layer, mainly composed of pigskin gelatin and glycerin, serves as the wear-resistant layer to enhance anti-friction performance. At the same time, the highly adhesive mixed gelatin layer firmly adheres the wear-resistant layer to the surface of the heat-sensitive layer of the thermal paper, while glycerin gives the mixed gelatin layer or pigskin gelatin layer good flexibility. This makes the wear-resistant, heat-sensitive color-developing protective layer less likely to fall off or peel off during use, thus giving the thermal paper excellent long-term anti-friction performance. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the wear-resistant, heat-sensitive, color-developing protective layer of the present invention;

[0026] Figure 2 SEM images of the medical thermal paper base paper and the wear-resistant thermal color-developing protective layer in Example 1. Detailed Implementation

[0027] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0029] Both fish skin gelatin and pig skin gelatin were purchased from Pusitang Reagent Network. The gel strength of the fish skin gelatin was 220 g bloom, and the gel strength of the pig skin gelatin was 280 g bloom.

[0030] Example 1

[0031] An embodiment of the wear-resistant, heat-sensitive, color-developing protective layer of the present invention (e.g.) Figure 1 As shown in the figure, the wear-resistant heat-sensitive color-developing protective layer in this embodiment includes a mixed gelatin layer (average thickness of 5 μm) and a pigskin gelatin layer (average thickness of 10 μm) that are bonded together; the mixed gelatin layer is composed of fish skin gelatin, pigskin gelatin and glycerin in a mass ratio of 10:3:5, and the pigskin gelatin layer is composed of pigskin gelatin and glycerin in a mass ratio of 10:1.

[0032] The method for preparing the wear-resistant, heat-sensitive, color-developing protective layer described in this embodiment includes the following steps:

[0033] S1, 30 g of pigskin gelatin powder was soaked in 67 g of distilled water, fully swelled for 1 h, then 3 g of glycerol was added after stirring at 50 DEG C and 500 rpm for 30 min, and stirring was continued for 30 min to obtain a transparent solution; then the transparent solution was coated on the surface of a glass plate, and air dried at room temperature for 24 h to obtain a pigskin gelatin-based film;

[0034] S2, 10 g of fishskin gelatin powder and 3 g of pigskin gelatin powder were soaked in 82 g of distilled water, fully swelled for 1 h, then 5 g of glycerol was added after stirring at 50 DEG C and 500 rpm for 30 min, and stirring was continued for 30 min to obtain a transparent solution, which was a fishskin gelatin-based solution;

[0035] S3, using the medical thermal paper base paper (such as the one shown in a of Figure 2 The fishskin gelatin-based solution in S2 was uniformly coated on the surface of the carrier to form a fishskin gelatin-based solution layer, then the pigskin gelatin-based film in S1 was attached to the surface of the fishskin gelatin-based solution layer, and dried at 90 DEG C for 12 h to obtain a wear-resistant thermal sensitive color developing protective layer (such as the one shown in b of Figure 2

[0036] Example 2

[0037] One embodiment of the wear-resistant thermal sensitive color developing protective layer of the present application, the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is basically the same as that in Example 1, and the difference lies in that the mixed gelatin layer is composed of fishskin gelatin, pigskin gelatin and glycerol in a mass ratio of 10:7:5.

[0038] The preparation method of the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is the same as that in Example 1.

[0039] Example 3

[0040] One embodiment of the wear-resistant thermal sensitive color developing protective layer of the present application, the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is basically the same as that in Example 1, and the difference lies in that the mixed gelatin layer is composed of fishskin gelatin, pigskin gelatin and glycerol in a mass ratio of 10:3:1.

[0041] The preparation method of the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is the same as that in Example 1.

[0042] Example 4

[0043] One embodiment of the wear-resistant thermal sensitive color developing protective layer of the present application, the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is basically the same as that in Example 1, and the difference lies in that the mixed gelatin layer is composed of fishskin gelatin, pigskin gelatin and glycerol in a mass ratio of 10:3:10.

[0044] The preparation method of the wear-resistant thermal sensitive color developing protective layer described in the present embodiment is the same as that in Example 1. ​

[0045] Example 5

[0046] In one embodiment of the present application, the wear-resistant heat-sensitive color developing protective layer is substantially the same as that of Example 1, except that the average thickness of the mixed gelatin layer is 3 μm and the average thickness of the pigskin gelatin layer is 5 μm.

[0047] The preparation method of the wear-resistant heat-sensitive color developing protective layer of the present embodiment is the same as that of Example 1.

[0048] Comparative Example 1

[0049] In one comparative example of the present application, the wear-resistant heat-sensitive color developing protective layer is composed of pigskin gelatin and glycerol at a mass ratio of 10:1, and has an average thickness of 10 μm.

[0050] The preparation method of the wear-resistant heat-sensitive color developing protective layer of the present comparative example comprises the following steps:

[0051] 30 g of pigskin gelatin powder was soaked in 67 g of distilled water, and after being fully swelled for 1 h, 3 g of glycerol was added under the condition of 50 °C and 500 rpm for 30 min, and the transparent solution was obtained after continuous stirring for 30 min; then the transparent solution was uniformly coated on the surface of the carrier (medical thermal paper base paper), and the wear-resistant heat-sensitive color developing protective layer was obtained after air drying at room temperature for 24 h.

[0052] Comparative Example 2

[0053] In one comparative example of the present application, the wear-resistant heat-sensitive color developing protective layer is composed of pigskin gelatin, pigskin gelatin and glycerol at a mass ratio of 10:3:5, and has an average thickness of 10 μm.

[0054] The preparation method of the wear-resistant heat-sensitive color developing protective layer of the present comparative example comprises the following steps:

[0055] 10 g of fishskin gelatin powder and 3 g of pigskin gelatin powder were soaked in 82 g of distilled water, and after being fully swelled for 1 h, 5 g of glycerol was added under the condition of 50 °C and 500 rpm for 30 min, and the transparent solution was obtained after continuous stirring for 30 min, which was the fishskin gelatin-based solution; then the fishskin gelatin-based solution was uniformly coated on the surface of the carrier (medical thermal paper base paper), and the wear-resistant heat-sensitive color developing protective layer was obtained after air drying at room temperature for 24 h.

[0056] Comparative Example 3

[0057] A kind of comparative example of the wear-resistant heat-sensitive color development protective layer of the present application, the wear-resistant heat-sensitive color development protective layer described in this embodiment includes mutually adhered fish skin gelatin layer (average thickness of 5 μm) and pigskin gelatin layer (average thickness of 10 μm);The fish skin gelatin layer is composed of fish skin gelatin and glycerol in a mass ratio of 10:5, and the pigskin gelatin layer is composed of pigskin gelatin and glycerol in a mass ratio of 10:1.

[0058] The preparation method of the wear-resistant heat-sensitive color development protective layer described in this comparative example includes the following steps:

[0059] S1, 30g of pigskin gelatin powder is soaked in 67g of distilled water, fully swelled for 1h, then 3g of glycerol is added under the condition of 50℃ and 500rpm stirring for 30min, and continue to stir for 30min to obtain a transparent solution;Then the transparent solution is coated on the surface of the glass plate, and dried at room temperature for 24h to obtain a pigskin gelatin-based film;

[0060] S2, 10g of fish skin gelatin powder is soaked in 82g of distilled water, fully swelled for 1h, then 5g of glycerol is added under the condition of 50℃ and 500rpm stirring for 30min, and continue to stir for 30min to obtain a transparent solution, which is a fish skin gelatin-based solution;

[0061] S3, with medical heat-sensitive paper base paper as carrier, the fish skin gelatin-based solution in S2 is uniformly coated on the surface of the carrier to form a fish skin gelatin-based solution layer, then the pigskin gelatin-based film in S1 is adhered to the surface of the fish skin gelatin-based solution layer, and dried at 90℃ for 12h to obtain a wear-resistant heat-sensitive color development protective layer.

[0062] Performance test

[0063] Since the wear-resistant heat-sensitive color development protective layer in examples 1-5 and comparative examples 1-3 of the present application is prepared with medical heat-sensitive paper base paper as carrier, it can be directly used as the sample to be tested for the following tests, and the test results are shown in Table 1.

[0064] 1) Wear resistance test

[0065] Test method: wear resistance test of wear-resistant heat-sensitive color development protective layer is carried out by using a grinding machine, wherein the mass of the grinding wheel of the grinding machine is 100g, the rotating speed of the grinding machine is 60r / min, and the test time is 50min (3000r in total);The mass of the sample before and after the test is weighed as m1 and m2 respectively, and the mass loss of the wear-resistant heat-sensitive color development protective layer is calculated by the following formula, that is, the smaller the mass loss, the better the wear resistance of the wear-resistant heat-sensitive color development protective layer;

[0066] Mass loss (%) = (m1-m2) / m1*100%.

[0067] 2) Adhesion test

[0068] Test method: The 90° peeling mode in the tensile testing instrument (Instron 5566, USA) was used to test the adhesion of the wear-resistant heat-sensitive color developing protective layer.

[0069] The properties of the wear-resistant heat-sensitive color developing protective layer in each example and the comparative example in Table 1

[0070] Sample Mass loss (%) Adhesion properties (N / m) Example 1 2.1 110.7 Example 2 2.0 60.0 Example 3 2.0 100.1 Example 4 2.1 90.5 Example 5 2.3 104.5 Comparative Example 1 2.3 58.2 Comparative Example 2 3.5 105.5 Comparative Example 3 4.9 111.2

[0071] According to the data in Table 1, the mass loss rate of the wear-resistant heat-sensitive color developing protective layer in Examples 1-5 is less than or equal to 2.3%, and the adhesion is 60-110.7 N / m, indicating that the wear-resistant heat-sensitive color developing protective layer of the present application has good adhesion and excellent wear resistance. In addition, according to Comparative Examples 1 and 2, it can be found that the pigskin gelatin layer or the mixed gelatin layer alone as the wear-resistant heat-sensitive color developing protective layer is difficult to maintain good adhesion while effectively improving wear resistance; according to Comparative Example 3, it can be found that when the gelatin in the mixed gelatin layer is only fish skin gelatin, although it is beneficial to improve the adhesion of the wear-resistant heat-sensitive color developing protective layer, it also leads to a significant decrease in the wear resistance of the wear-resistant heat-sensitive color developing protective layer.

[0072] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A wear resistant heat sensitive color revealing protective layer characterized in that, The mixed gelatin layer comprises fish skin gelatin, pigskin gelatin and glycerol, and the pigskin gelatin layer comprises pigskin gelatin and glycerol. The mass ratio of fish skin gelatin, pigskin gelatin and glycerol in the mixed gelatin layer is 10:(2-8):(1-10), and the mass ratio of pigskin gelatin and glycerol in the pigskin gelatin layer is 10:(0.5-1.5). The average thickness of the mixed gelatin layer is 3-5 μm, and the average thickness of the pigskin gelatin layer is 5-10 μm.

2. The wear resistant heat sensitive color revealing protective layer of claim 1, wherein, The fish skin gelatin has a jelly strength of 200-240 g bloom. The pigskin gelatin has a jelly strength of 260-300 g bloom.

3. The method of claim 1 or 2 for the preparation of a wear resistant heat sensitive color revealing protective layer, characterized in that, The method comprises the following steps: First, a fish skin gelatin-based solution is coated on the surface of a carrier, and then a pigskin gelatin-based film is attached to the surface of the fish skin gelatin-based solution, and dried to obtain the wear-resistant heat-sensitive color developing protective layer. The fish skin gelatin-based solution comprises fish skin gelatin, pigskin gelatin, glycerol and water, and the mass fraction of fish skin gelatin in the fish skin gelatin-based solution is 5%-30%. The pigskin gelatin-based film is obtained by drying a pigskin gelatin-based solution, and the pigskin gelatin-based solution comprises pigskin gelatin, glycerol and water, and the mass fraction of pigskin gelatin in the pigskin gelatin-based solution is 20%-40%.

4. The production method according to claim 3, wherein The fish skin gelatin-based solution is prepared by the following method: fish skin gelatin and pigskin gelatin are soaked in water for 20-90 min, then stirred at 45-60 ℃ for 10-30 min, and glycerol is added and mixed uniformly to obtain the fish skin gelatin-based solution. The pigskin gelatin-based solution is prepared by the following method: pigskin gelatin is soaked in water for 20-90 min, then stirred at 45-60 ℃ for 10-30 min, and glycerol is added and mixed uniformly to obtain the pigskin gelatin-based solution.

5. Use of the wear-resistant heat-sensitive color developing protective layer of claim 1 or 2 in the preparation of heat-sensitive paper.

6. A thermal paper comprising a thermal paper base paper, a thermal color developing coating layer, and a protective layer, characterized in that, The protective layer is the wear-resistant heat-sensitive color developing protective layer of claim 1 or 2, and the mixed gelatin layer in the wear-resistant heat-sensitive color developing protective layer is in contact with the heat-sensitive color developing coating in the heat-sensitive paper.

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