Wear-resistant thermosensitive developing protective layer as well as preparation method and application thereof

Abstract

The invention relates to a wear-resistant thermosensitive developing protective layer as well as a preparation method and application thereof, and belongs to the technical field of slurry or paper pulp compositions. The wear-resistant thermosensitive developing protective layer comprises a mixed gelatin layer and a pigskin gelatin layer which are attached 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. The wear-resistant thermosensitive developing protective layer not only has excellent wear resistance, but also has high adhesion, and can be firmly attached to the surface of thermosensitive paper, so that the anti-friction performance of the thermosensitive paper is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of slurry or pulp composition, and in particular to a wear-resistant heat-sensitive protective layer and a preparation method and application thereof. Background Art

[0002] Thermal paper is generally composed of a base paper and a coating (the coating can be two or three layers, including a pre-coating layer, a thermal layer and a protective layer), wherein the base paper is usually a common paper base with high smoothness, heat preservation, flatness, no impurities, no holes and good tensile strength; the pre-coating layer prevents heat from being transferred to the inside of the paper and ensures that the heat can be effectively trapped between the protective layer and the pre-coating layer, thereby providing temperature protection for the reaction between the thermal layer developer and the colorless dye; the thermal layer usually includes components such as colorless fuel, sensitizer, developer and adhesive, which can produce color under the heating action of the thermal print head; the protective layer can enhance the waterproof, oil-proof or scratch-resistant properties of thermal paper. However, in actual application, it is found that although the surface of thermal paper is provided with a protective layer, during long-term storage or use, there is still a problem that the graphic or barcode information cannot be recognized due to the poor scratch resistance of the thermal paper. In order to solve the problem of poor anti-scratch performance of thermal paper, the prior art (CN106149465A) discloses a scratch-resistant thermal paper, which solves the problem by setting an anti-scratch layer composed of filler, petroleum extracts and adhesive between the thermal layer and the protective layer of the thermal paper; although this method can improve the anti-scratch performance of the thermal paper, the degree of improvement is limited. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a wear-resistant thermosensitive color-developing protective layer and a preparation method and application thereof.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] In a first aspect, the present invention provides a wear-resistant thermosensitive color-developing protective layer, which includes a mixed gelatin layer and a pigskin gelatin layer bonded to each other; the mixed gelatin layer includes fish skin gelatin, pigskin gelatin and glycerin, and the pigskin gelatin layer includes pigskin gelatin and glycerin.

[0006] The present invention combines a mixed gelatin layer and a pigskin gelatin layer to form a wear-resistant thermosensitive color-developing protective layer with a double-layer structure ("Janus" structure), and uses the pigskin gelatin layer mainly composed of pigskin gelatin and glycerin as the wear-resistant layer to enhance the anti-friction performance. At the same time, the mixed gelatin layer with high adhesion can firmly attach the wear-resistant layer to the surface of the thermal layer of the thermal paper, and glycerin can make the mixed gelatin layer and the pigskin gelatin layer have good flexibility, so that the wear-resistant thermosensitive color-developing protective layer is not easy to fall off or peel off during use, thereby giving the thermal paper excellent long-term anti-friction performance.

[0007] As a preferred embodiment of the wear-resistant thermosensitive color-developing protective layer of the present invention, the mass ratio of fish skin gelatin, pig skin gelatin and glycerin in the mixed gelatin layer is 10:(2-8):(1-10). Optionally, in parts by weight, the fish skin gelatin in the mixed gelatin layer can be 10 parts, the pig skin gelatin can be 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 glycerin can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts.

[0008] The study found that by adjusting the mass ratio between fish skin gelatin, pig skin gelatin and glycerol, the mechanical strength of the mixed gelatin layer can be controlled to effectively prevent it from being damaged during actual application; moreover, when the mass ratio of fish skin gelatin, pig skin gelatin and glycerol is within the above range, it can not only give the mixed gelatin layer high adhesion, but also give it good mechanical strength and flexibility.

[0009] As a preferred embodiment of the wear-resistant thermosensitive color-developing protective layer of the present invention, the mass ratio of pigskin gelatin to glycerol in the pigskin gelatin layer is 10:(0.5-1.5). Optionally, the mass ratio of pigskin gelatin to glycerol in the pigskin gelatin layer can be 10:0.6, 10:0.8, 10:1, 10:1.2, 10:1.4. Studies have found that when the mass ratio of pigskin gelatin to 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 thermosensitive color-developing protective layer of the present invention, the average thickness of the mixed gelatin layer is 3-5 μm. Optionally, the average thickness of the mixed gelatin layer can be 3.5 μm, 4 μm, or 4.5 μm.

[0011] As a preferred embodiment of the wear-resistant thermosensitive color-developing protective layer of the present invention, the average thickness of the pigskin gelatin layer is 5 to 10 μm. Optionally, the average thickness of the pigskin gelatin layer can be 6 μm, 7 μm, 8 μm, or 9 μm.

[0012] As a preferred embodiment of the wear-resistant thermosensitive color-developing protective layer of the present invention, the jelly strength of the fish skin gelatin is 200-240g Bloom; and / or, the jelly strength of the pig skin gelatin is 260-300g Bloom. Optionally, the jelly strength of the fish skin gelatin can be specifically 210g Bloom, 220g Bloom, 230g Bloom; the jelly strength of the pig skin gelatin can be specifically 270g Bloom, 280g Bloom, 290g Bloom.

[0013] In a second aspect, the present invention provides a method for preparing the above-mentioned wear-resistant thermosensitive color-developing protective layer, comprising the following steps:

[0014] Firstly, a fish skin gelatin-based solution is coated on the surface of a carrier, and then a pig skin gelatin-based film is attached to the surface of the fish skin gelatin-based solution, and dried to obtain a wear-resistant thermosensitive color-developing protective layer;

[0015] The fish skin gelatin-based solution comprises fish skin gelatin, pig skin gelatin, glycerin and water, and the mass fraction of 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; the pigskin gelatin-based solution comprises pigskin gelatin, glycerin and water, and the mass fraction of pigskin gelatin in the pigskin gelatin-based solution is 20% to 40%.

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

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

[0019] And / or, the pigskin gelatin-based solution is prepared by the following preparation method: soaking pigskin gelatin in water to swell for 20 to 90 minutes, then stirring at 45 to 60° C. for 10 to 30 minutes, and then adding glycerin and mixing evenly to obtain the fish skin gelatin-based solution.

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

[0021] In a third aspect, the present invention provides the use of the above-mentioned wear-resistant thermosensitive color-developing protective layer in the preparation of thermal paper.

[0022] In a fourth aspect, the present invention provides a thermal paper, comprising a thermal paper base, a thermal color developing coating and a protective layer, wherein the protective layer is the above-mentioned 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 present invention has the following beneficial effects:

[0024] The present invention combines a mixed gelatin layer and a pigskin gelatin layer to form a wear-resistant thermosensitive color developing protective layer with a double-layer structure, and uses the pigskin gelatin layer mainly composed of pigskin gelatin and glycerin as the wear-resistant layer to enhance the anti-friction performance. At the same time, the mixed gelatin layer with high adhesion can firmly attach the wear-resistant layer to the surface of the thermal layer of the thermal paper, and glycerin can make the mixed gelatin layer or the pigskin gelatin layer have good flexibility, so that the wear-resistant thermosensitive color developing protective layer is not easy to fall off or peel off during use, thereby giving the thermal paper excellent long-term anti-friction performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 2 This is a SEM image of the medical thermal paper base and the wear-resistant thermal color-developing protective layer in Example 1. DETAILED DESCRIPTION

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

[0028] Unless otherwise specified, other materials, reagents, etc. used in the examples can be obtained from commercial sources.

[0029] Fish skin gelatin and pig skin gelatin were purchased from Puxitang Reagent Network, wherein the jelly strength of fish skin gelatin was 220 g bloom, and the jelly strength of pig skin gelatin was 280 g bloom.

[0030] Example 1

[0031] An embodiment of the wear-resistant thermosensitive color-developing protective layer of the present invention (such as Figure 1 As shown in the figure, the wear-resistant thermosensitive color-developing protective layer described in this embodiment includes a mixed gelatin layer (with an average thickness of 5 μm) and a pigskin gelatin layer (with an average thickness of 10 μm) bonded to each other; the mixed gelatin layer is composed of fish skin gelatin, pigskin gelatin and glycerol in a mass ratio of 10:3:5, and the pigskin gelatin layer is composed of pigskin gelatin and glycerol in a mass ratio of 10:1.

[0032] The method for preparing the wear-resistant thermosensitive color-developing protective layer described in this embodiment comprises the following steps:

[0033] S1, soak 30g of pigskin gelatin powder in 67g of distilled water, fully swell for 1h, stir at 50°C and 500rpm for 30min, add 3g of glycerol, and continue stirring for 30min to obtain a transparent solution; then apply the transparent solution on the surface of a glass plate, air-dry at room temperature for 24h to obtain a pigskin gelatin-based film;

[0034] S2, 10g of fish skin gelatin powder and 3g of pig skin gelatin powder were soaked in 82g of distilled water, fully swollen for 1h, and then 5g of glycerol was added after stirring for 30min at 50°C and 500rpm, and a transparent solution was obtained after continuing to stir for 30min, which was the fish skin gelatin-based solution;

[0035] S3, medical thermal paper base paper (such as Figure 2 The fish skin gelatin-based solution in S2 is evenly coated on the surface of the carrier to form a fish skin gelatin-based solution layer, and then the pig skin gelatin-based film in S1 is attached to the surface of the fish skin gelatin-based solution layer, and dried at 90° C. for 12 h to obtain a wear-resistant thermosensitive color-developing protective layer (as shown in FIG. Figure 2 (as shown in b in the figure).

[0036] Example 2

[0037] An embodiment of a wear-resistant thermosensitive color developing protective layer of the present invention, the wear-resistant thermosensitive color developing protective layer described in this embodiment is basically the same as that in embodiment 1, the difference being that the mixed gelatin layer is composed of fish skin gelatin, pig skin gelatin and glycerin in a mass ratio of 10:7:5.

[0038] The preparation method of the wear-resistant thermosensitive color-developing protective layer described in this embodiment is the same as that in Embodiment 1.

[0039] Example 3

[0040] An embodiment of a wear-resistant thermosensitive color developing protective layer of the present invention, the wear-resistant thermosensitive color developing protective layer described in this embodiment is basically the same as that in embodiment 1, the difference is that: the mixed gelatin layer is composed of fish skin gelatin, pig skin gelatin and glycerin in a mass ratio of 10:3:1.

[0041] The preparation method of the wear-resistant thermosensitive color-developing protective layer described in this embodiment is the same as that in Embodiment 1.

[0042] Example 4

[0043] An embodiment of the wear-resistant thermosensitive color developing protective layer of the present invention, the wear-resistant thermosensitive color developing protective layer described in this embodiment is basically the same as that in embodiment 1, the difference is that: the mixed gelatin layer is composed of fish skin gelatin, pig skin gelatin and glycerin in a mass ratio of 10:3:10.

[0044] The preparation method of the wear-resistant thermosensitive color-developing protective layer described in this embodiment is the same as that in Embodiment 1.

[0045] Example 5

[0046] An embodiment of the wear-resistant thermosensitive color developing protective layer of the present invention, the wear-resistant thermosensitive color developing protective layer described in this embodiment is basically the same as that in embodiment 1, the difference is that: the average thickness of the mixed gelatin layer is 3μm, and the average thickness of the pigskin gelatin layer is 5μm.

[0047] The preparation method of the wear-resistant thermosensitive color-developing protective layer described in this embodiment is the same as that in Embodiment 1.

[0048] Comparative Example 1

[0049] A comparative example of the wear-resistant thermosensitive color-developing protective layer of the present invention, wherein the wear-resistant thermosensitive color-developing protective layer in this comparative example is composed of pigskin gelatin and glycerin in a mass ratio of 10:1, and has an average thickness of 10 μm.

[0050] The method for preparing the wear-resistant thermosensitive color-developing protective layer described in this comparative example comprises the following steps:

[0051] 30 g of pig skin gelatin powder was soaked in 67 g of distilled water. After fully swelling for 1 hour, 3 g of glycerol was added after stirring at 50°C and 500 rpm for 30 minutes, and stirring was continued for 30 minutes to obtain a transparent solution; the transparent solution was then evenly coated on the surface of the carrier (medical thermal paper base paper), and air-dried at room temperature for 24 hours to obtain a wear-resistant thermal color-developing protective layer.

[0052] Comparative Example 2

[0053] A comparative example of the wear-resistant thermosensitive color-developing protective layer of the present invention, the wear-resistant thermosensitive color-developing protective layer in this comparative example is composed of fish skin gelatin, pig skin gelatin and glycerin in a mass ratio of 10:3:5, and has an average thickness of 10 μm.

[0054] The method for preparing the wear-resistant thermosensitive color-developing protective layer described in this comparative example comprises the following steps:

[0055] 10 g of fish skin gelatin powder and 3 g of pig skin gelatin powder were soaked in 82 g of distilled water. After fully swelling for 1 hour, 5 g of glycerol was added after stirring at 50°C and 500 rpm for 30 minutes. After continuing to stir for 30 minutes, a transparent solution was obtained, which was the fish skin gelatin-based solution. The fish skin gelatin-based solution was then evenly coated on the surface of the carrier (medical thermal paper base paper), and air-dried at room temperature for 24 hours to obtain a wear-resistant thermal color-developing protective layer.

[0056] Comparative Example 3

[0057] A comparative example of the wear-resistant thermosensitive color-developing protective layer of the present invention, the wear-resistant thermosensitive color-developing protective layer described in this embodiment includes a fish skin gelatin layer (with an average thickness of 5 μm) and a pig skin gelatin layer (with an average thickness of 10 μm) bonded to each other; the fish skin gelatin layer is composed of fish skin gelatin and glycerol in a mass ratio of 10:5, and the pig skin gelatin layer is composed of pig skin gelatin and glycerol in a mass ratio of 10:1.

[0058] The method for preparing the wear-resistant thermosensitive color-developing protective layer described in this comparative example comprises the following steps:

[0059] S1, soak 30g of pigskin gelatin powder in 67g of distilled water, fully swell for 1h, stir at 50°C and 500rpm for 30min, add 3g of glycerol, and continue stirring for 30min to obtain a transparent solution; then apply the transparent solution on the surface of a glass plate, air-dry at room temperature for 24h to obtain a pigskin gelatin-based film;

[0060] S2, 10g of fish skin gelatin powder was immersed in 82g of distilled water, fully swollen for 1h, then 5g of glycerol was added after stirring for 30min at 50°C and 500rpm, and a clear solution was obtained after continuing to stir for 30min, which was a fish skin gelatin-based solution;

[0061] S3, using medical thermal paper as a carrier, the fish skin gelatin-based solution in S2 is evenly coated on the surface of the carrier to form a fish skin gelatin-based solution layer, and then the pig skin gelatin-based film in S1 is attached to the surface of the fish skin gelatin-based solution layer, and dried at 90° C. for 12 hours to obtain a wear-resistant thermal color-developing protective layer.

[0062] Performance Testing

[0063] Since the wear-resistant thermosensitive color-developing protective layers in Examples 1 to 5 of the present invention and Comparative Examples 1 to 3 are prepared using medical thermal paper as a carrier, they can be directly used as samples to be tested as follows. The test results are shown in Table 1.

[0064] 1) Wear resistance test

[0065] Test method: The wear resistance of the wear-resistant thermosensitive color-developing protective layer is tested by a wear machine, wherein the mass of the grinding wheel of the wear machine is 100g, the speed of the wear machine is 60 rpm, and the time is 50min (3000 rpm in total); the mass m1 of the sample before the test and the mass m2 after the test are weighed, and the mass loss of the wear-resistant thermosensitive color-developing protective layer is calculated by the following formula. The smaller the mass loss, the better the wear resistance of the wear-resistant thermosensitive color-developing protective layer;

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

[0067] 2) Adhesion performance test

[0068] Test method: The adhesion performance of the wear-resistant thermosensitive color-developing protective layer was tested using a 90° peeling mode in a tensile tester (Instron 5566, USA).

[0069] Table 1 Performance of the wear-resistant thermosensitive color-developing protective layer in each embodiment and comparative example

[0070] sample Mass loss (%) Adhesion performance (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 thermosensitive color-developing protective layer in Examples 1 to 5 is less than or equal to 2.3%, and the adhesion performance reaches 60 to 110.7 N / m, indicating that the wear-resistant thermosensitive color-developing protective layer of the present invention has both good adhesion performance and excellent wear resistance. In addition, according to Comparative Examples 1 and 2, it can be found that it is difficult to maintain good adhesion performance while effectively improving wear resistance when using a pigskin gelatin layer or a mixed gelatin layer as a wear-resistant thermosensitive color-developing protective layer alone; according to Comparative Example 3, when the gelatin in the mixed gelatin layer is only fish skin gelatin, although it is beneficial to improve the adhesion performance of the wear-resistant thermosensitive color-developing protective layer, it also causes the wear resistance of the wear-resistant thermosensitive color-developing protective layer to be greatly reduced.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A wear-resistant thermosensitive color-developing protective layer, characterized in that: It comprises a mixed gelatin layer and a pigskin gelatin layer which are bonded to each other; the mixed gelatin layer comprises fish skin gelatin, pigskin gelatin and glycerin, and the pigskin gelatin layer comprises pigskin gelatin and glycerin.

2. The wear-resistant thermosensitive color-developing protective layer according to claim 1, characterized in that: The mass ratio of fish skin gelatin, pig skin gelatin and glycerin in the mixed gelatin layer is 10:(2-8):(1-10).

3. The wear-resistant thermosensitive color-developing protective layer according to claim 1, characterized in that: The mass ratio of pigskin gelatin to glycerol in the pigskin gelatin layer is 10:(0.5-1.5).

4. The wear-resistant thermosensitive color-developing protective layer according to claim 1, characterized in that: The average thickness of the mixed gelatin layer is 3 to 5 μm.

5. The wear-resistant thermosensitive color-developing protective layer according to claim 1, characterized in that: The average thickness of the pigskin gelatin layer is 5 to 10 μm.

6. The wear-resistant thermosensitive color-developing protective layer according to claim 1, characterized in that: The jelly strength of the fish skin gelatin is 200-240 g bloom; And / or, the pigskin gelatin has a jelly strength of 260-300 g bloom.

7. The method for preparing the wear-resistant thermosensitive color-developing protective layer according to any one of claims 1 to 6, characterized in that: The following steps are involved: Firstly, a fish skin gelatin-based solution is coated on the surface of a carrier, and then a pig skin gelatin-based film is attached to the surface of the fish skin gelatin-based solution, and dried to obtain a wear-resistant thermosensitive color-developing protective layer; The fish skin gelatin-based solution comprises fish skin gelatin, pig skin gelatin, glycerin and water, and the mass fraction of fish skin gelatin in the fish skin gelatin-based solution is 5% to 30%; The pigskin gelatin-based film is obtained by drying a pigskin gelatin-based solution; the pigskin gelatin-based solution comprises pigskin gelatin, glycerin and water, and the mass fraction of pigskin gelatin in the pigskin gelatin-based solution is 20% to 40%.

8. The preparation method according to claim 7, characterized in that: The fish skin gelatin-based solution is prepared by the following preparation method: soaking fish skin gelatin and pig skin gelatin in water to swell for 20 to 90 minutes, then stirring at 45 to 60° C. for 10 to 30 minutes, and then adding glycerin to mix evenly to obtain the fish skin gelatin-based solution; And / or, the pigskin gelatin-based solution is prepared by the following preparation method: soaking pigskin gelatin in water to swell for 20 to 90 minutes, then stirring at 45 to 60° C. for 10 to 30 minutes, and then adding glycerin and mixing evenly to obtain the pigskin gelatin-based solution.

9. Use of the wear-resistant thermosensitive color-developing protective layer according to any one of claims 1 to 6 in the preparation of thermal paper.

10. A thermal paper, comprising a thermal paper base, a thermal color developing coating and a protective layer, characterized in that: The protective layer is the wear-resistant thermosensitive color-developing protective layer according to any one of claims 1 to 6; the mixed gelatin layer in the wear-resistant thermosensitive color-developing protective layer is in contact with the thermosensitive color-developing coating in the thermal paper.

Images