Paper pink pencil handwriting display reinforcing agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of reinforcement and repair of paper archives, and relates to a paper pink pencil handwriting display reinforcing agent and a preparation method and application thereof, the paper pink pencil handwriting display reinforcing agent is formed by ethyl cellulose, an organic solvent, diphenyl-isooctyl phosphite and bis (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate; the volume ratio of the organic solvent to the diphenyl-isooctyl phosphite to the bis (1, 2, 2, 6, 6-pentamethyl-4-piperidyl) sebacate is (14 to 16): (2 to 3): 1; 3 g of ethyl cellulose is added into every 100 mL of the organic solvent; the organic solvent is formed by mixing ethyl acetate, acetone and n-butyl alcohol which are equal in volume. The display reinforcing agent disclosed by the invention has excellent anti-hydrophilic property, and the pink pencil writing is not easy to fall off; the blue printing paper also has the effect of inhibiting light scattering, so that the handwriting developing definition is improved, the blue printing paper is not easy to age and fade, and long-term storage of the blue printing paper is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of paper archive reinforcement and restoration, and relates to a paper pastel pencil handwriting revealing and reinforcing agent, a preparation method and application thereof. The paper pastel pencil handwriting revealing and reinforcing agent is used for revealing and reinforcing paper pastel pencil handwriting on engineering blueprints. Background Art

[0002] There are two types of engineering drawings used in engineering in the early days: diazonium salt-based drawings and iron salt-based drawings. Engineering drawings require the original drawing to be drawn first, then the base drawing to be traced, and finally the blueprint to be printed. They are characterized by being unmodifiable and requiring batch repetitive production. They are specially used for various engineering designs and mechanical manufacturing drawings, and are essential supplies for production, scientific research, and construction. In addition to the printed handwriting that records important information on the printed drawings, special colored pencils are also used to mark the printed drawings during actual on-site use, thus producing another special pencil handwriting that carries information, also known as paper pastel lead handwriting. This special pencil handwriting is neither conjunctival nor absorbed on the printed drawings. It is filled in powder form or adheres to the surface of the printed drawings. It is easily rubbed off during flipping through the pages and will also fall off when exposed to water, resulting in the loss of the marked information and affecting reading. Therefore, it is necessary to protect this paper pastel lead handwriting.

[0003] A common method for reinforcing pastel pencil writing on paper involves mixing a certain proportion of rosin and petroleum ether to form a protective agent. The paper is then completely immersed in the protective agent and allowed to stand for half a minute. The paper is then removed and placed in a cool, ventilated area until the protective agent evaporates, forming a thin, reinforcing film on the surface of the paper, thereby protecting the pastel pencil writing. However, this reinforcement method has the following drawbacks: the reinforcing film's strong hydrophilicity results in insufficient water resistance, causing the pastel pencil writing to absorb water and fall off. Furthermore, the existing use of rosin and petroleum ether to form a reinforcing film causes light scattering, making the writing unclear and susceptible to aging and fading during long-term storage. Summary of the Invention

[0004] In view of the technical problems in the existing reinforcement of paper pastel pencil writing, such as the strong hydrophilicity of the reinforcing film, which makes the water resistance insufficient, the paper pastel pencil writing absorbs water and falls off, and produces a light scattering effect, making the writing unclear, and causing it to age and fade easily during long-term storage, the present invention provides a paper pastel pencil writing visualization reinforcement agent, a preparation method and application thereof.

[0005] The present invention comprises ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate to form a developing reinforcing agent, which has excellent anti-hydrophilicity and prevents pastel pencil writing from falling off easily. The invention also has the function of inhibiting light scattering, thereby improving the color clarity of writing and preventing aging and fading, thereby realizing long-term preservation of the printing paper.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A paper pastel pencil handwriting enhancement agent is formed from ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate;

[0008] The volume ratio of the organic solvent, diphenyl 2-isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate is (14-16):(2-3):1;

[0009] Add 2g to 3g of ethyl cellulose to every 100mL of organic solvent.

[0010] It is further defined that the organic solvent is a mixture of equal volumes of ethyl acetate, acetone and n-butanol.

[0011] It was further determined that the water contact angle of the paper pastel pencil handwriting enhancement agent after reinforcement of the sundry paper increased by 53.15°.

[0012] It is further specified that the emissivity of the paper pastel pencil writing enhancement agent is 10.06% at a wavelength of 550nm and 23.20% at a wavelength of 700nm.

[0013] It is further specified that the glossiness of the paper pastel pencil writing enhancement agent at incident angles of 20°, 45° and 75° before aging is 4.9, 2.1 and 3.5 respectively; after aging, the glossiness at incident angles of 20°, 45° and 75° is at least 4.8, 2.0 and 2.5 respectively.

[0014] A method for preparing the paper pastel pencil handwriting enhancement agent comprises the following steps:

[0015] S1. Mixing ethyl cellulose and an organic solvent, stirring uniformly in a water bath using a condensation reflux method until the ethyl cellulose is completely dissolved, to obtain an ethyl cellulose solution;

[0016] S2. Add diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate to the ethyl cellulose solution respectively, heat and stir, and mix evenly to obtain a paper pastel pencil handwriting visualization and reinforcement agent.

[0017] It is further defined that in step S1, the temperature of the water bath condition is 45° C. to 55° C.; and the stirring speed is 300 r / min to 400 r / min.

[0018] It is further defined that in step S2, the stirring time is 10 minutes to 15 minutes, and the stirring temperature is 45° C. to 55° C.

[0019] The paper pastel pencil handwriting revealing reinforcing agent is used to prevent paper pastel pencil handwriting from falling off on engineering blueprints.

[0020] The paper pastel pencil writing reinforcing agent is used to prevent the paper pastel pencil writing on engineering blueprints from aging and fading.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention uses ethyl cellulose, diphenyl 2-ethylhexyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate as main raw materials, and forms a visualization reinforcing agent in a specific ratio. Ethyl cellulose is used as a transparent film-forming material to wrap the pencil writing powder into a film to reinforce it on the printing paper. Since ethyl cellulose is not hydrophilic, the binding mode of the pencil writing powder and the printing paper becomes a conjunctiva, which greatly improves the water resistance of the pastel pencil writing and makes it less likely to absorb water and fall off. At the same time, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (GW-508) acts as a light stabilizer to fill the rough interface between the paper fiber and the pencil writing powder, inhibit light scattering, and make the writing clear. Diphenyl 2-ethylhexyl phosphite acts as an antioxidant to improve the antioxidant performance. The ethyl cellulose, antioxidant and light stabilizer work synergistically to prevent the pastel pencil writing from fading after aging during long-term storage.

[0023] 2. The present invention's paper pastel pencil marking enhancement agent, when used to reinforce engineering blueprints, increased the water contact angle of pastel pencil markings by up to 53.15°, demonstrating high hydrophobicity. This indicates the agent possesses excellent anti-hydrophilic properties, preventing pastel pencil markings from absorbing water and falling off.

[0024] 3. After the paper pastel pencil handwriting display reinforcement agent provided by the present invention is used to reinforce engineering sun-dried paper, the emissivity is 10.06% at a wavelength of 550nm and 23.20% at a wavelength of 700nm. The reflectivity is reduced and smoother overall, indicating that it has the effect of inhibiting light scattering, improving the color clarity of the handwriting, and maintaining color stability. After the paper pastel pencil handwriting display reinforcement agent is used to reinforce engineering sun-dried paper, the glossiness at incident angles of 20°, 45°, and 75° before aging is 4.9, 2.1, and 3.5, respectively; after aging, the glossiness at incident angles of 20°, 45°, and 75° is the lowest at 4.8, 2.0, and 2.5, respectively. This shows that the display reinforcement agent can effectively inhibit the color degradation caused by ultraviolet aging. It can be seen that the paper pastel pencil handwriting display reinforcement agent of the present invention effectively solves the problem of unclear pastel pencil handwriting powder on sun-dried paper, prevents aging and fading, and prolongs the shelf life of sun-dried paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 are reflectance curves under different aging conditions; among them: a and b are reflectance curves of unaged samples, c and d are reflectance curves of samples after damp heat aging, and e and f are reflectance curves of samples after UV aging;

[0026] Figure 2 dp is the reflectivity curve of the sample coated with the reinforcing agent with only the antioxidant DPOP solution added, dpsr is the reflectivity curve of the sample after wet heat aging, and dpzw is the reflectivity curve of the sample after UV aging;

[0027] Figure 3 Laser confocal microscopy before and after powder reinforcement;

[0028] Figure 4 Laser confocal microscopy of powder coated with only antioxidant DPOP reinforcement before and after reinforcement;

[0029] Figure 5 are infrared spectra under different aging conditions; among them: a and b are infrared spectra of unaged samples, c and d are infrared spectra of samples after damp heat aging, and e and f are infrared spectra of samples after UV aging;

[0030] Figure 6 is the infrared spectrum; dp is the infrared spectrum of the sample coated with the reinforcing agent with only the antioxidant DPOP solution added, dpsr is the infrared spectrum of the sample after wet heat aging, and dpzw is the infrared spectrum of the sample after UV aging;

[0031] Figure 7 is the contact angle of the powder sample;

[0032] Figure 8 The contact angle of the powder sample changes with time;

[0033] Figure 9 It is the pulverization degree of the powder sample. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto. Other methods for preparing the compounds of the present invention are considered to be within the scope of the present invention by making some conventional modifications to the reaction conditions of the present invention.

[0035] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0036] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

[0037] The invention provides a paper pastel pencil handwriting visualization reinforcing agent, which is formed from ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.

[0038] In the present invention, the volume ratio of the organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate is (14-16):(2-3):1; and 2g to 3g of ethyl cellulose is added to every 100mL of the organic solvent.

[0039] Exemplarily, the volume ratio of the organic solvent, diphenyl 2-octyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate is 14:2:1, 14:3:1, 15:2:1, 15:3:1, 16:2:1 or 16:3:1. Preferably, the volume ratio of the organic solvent, diphenyl 2-octyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate is 15:3:1.

[0040] Preferably, 3 g of ethyl cellulose is added to every 100 mL of organic solvent.

[0041] Preferably, the organic solvent is a mixture of equal volumes of ethyl acetate, acetone, and n-butanol. In forming the pastel pencil marking enhancer, ethyl acetate provides excellent solubility and volatility; acetone accelerates dissolution and reduces viscosity; and n-butanol regulates the rate of volatilization, preventing uneven film formation caused by excessive drying. This increases the dissolution rate of each raw material and ensures a consistent film after application to the printed paper.

[0042] The present invention also provides a method for preparing a paper pastel pencil handwriting visualization reinforcing agent, comprising the following steps:

[0043] S1. Mixing ethyl cellulose and an organic solvent, stirring uniformly in a water bath using a condensation reflux method until the ethyl cellulose is completely dissolved, to obtain an ethyl cellulose solution;

[0044] In step S1, the water bath temperature is 45° C. to 55° C., and the stirring speed is 300 rpm to 400 rpm. In step S2, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate are added to the ethyl cellulose solution, respectively, and heated and stirred to mix uniformly to obtain a paper pastel pencil writing enhancement agent.

[0045] In step S2, the stirring time is 10 min to 15 min, and the stirring temperature is 45° C. to 55° C.

[0046] Through testing, the paper pastel pencil handwriting visualization reinforcement agent provided by the present invention can increase the water contact angle of the reinforced paper by up to 53.15°. The emissivity at a wavelength of 550nm is 10.06%, and the emissivity at a wavelength of 700nm is 23.20%. The glossiness of the paper pastel pencil handwriting visualization reinforcement agent at incident angles of 20°, 45° and 75° before aging is 4.9, 2.1 and 3.5 respectively; after aging, the glossiness at incident angles of 20°, 45° and 75° is as low as 4.8, 2.0 and 2.5 respectively. Therefore, the paper pastel pencil handwriting visualization reinforcement agent provided by the present invention can be used to prevent paper pastel pencil handwriting on engineering sundry drawings from falling off and aging and fading.

[0047] The following describes in detail several groups of examples the paper pastel pencil handwriting visualization reinforcing agent, its preparation method and its application performance.

[0048] It should be noted that, in the following examples, unless otherwise specified, the chemicals and reagents used are all conventional commercial products in the art.

[0049] It should be noted that in the following examples, unless otherwise specified, the operations used are all conventional operations; for example, the operating temperature is room temperature unless otherwise specified. The test methods are all standard test methods available in the art unless otherwise specified.

[0050] Example 1

[0051] The paper pastel pencil handwriting enhancement agent provided in this embodiment is formed by ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.

[0052] Preferably, the volumes of the organic solvent, diphenyl isooctyl phosphite, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate are 60 mL, 12 mL, and 4 mL, respectively. The mass of the ethyl cellulose is 1.8 g.

[0053] The organic solvent was composed of 20 mL of ethyl acetate, 20 mL of acetone and 20 mL of n-butanol reagent.

[0054] In this embodiment, the preparation method of the paper pastel pencil handwriting enhancement agent is:

[0055] S1. Weigh 1.8 g of ethyl cellulose powder, 20 mL of ethyl acetate, 20 mL of acetone, and 20 mL of n-butanol reagent, place them in a three-necked flask, add a condensing reflux device, and stir evenly with a magnetic heating stirrer. Set the water bath temperature to 45-55°C and the stirring speed to 300-400 r / min until the ethyl cellulose is completely dissolved to obtain an ethyl cellulose solution with a mass concentration of 3%.

[0056] S2. Add 12 mL of diphenyl isooctyl phosphite (DPOP) and 4 mL of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate to the ethyl cellulose solution, and place the solution in a constant temperature magnetic stirring device for heating and stirring for 10 minutes until the solution is evenly mixed to obtain a paper pastel pencil handwriting revealing and reinforcing agent, referred to as the revealing and reinforcing agent.

[0057] Example 2

[0058] The paper pastel pencil handwriting enhancement agent provided in this embodiment is formed by ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.

[0059] Preferably, the volumes of the organic solvent, diphenyl isooctyl phosphite, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate are 56 mL, 8 mL, and 4 mL, respectively. The mass of the ethyl cellulose is 1.12 g.

[0060] The organic solvent was composed of 20 mL of ethyl acetate, 20 mL of acetone and 20 mL of n-butanol reagent.

[0061] In this embodiment, the preparation method of the paper pastel pencil handwriting revealing reinforcing agent is referred to Example 1.

[0062] Example 3

[0063] The paper pastel pencil handwriting enhancement agent provided in this embodiment is formed by ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate.

[0064] Preferably, the volumes of the organic solvent, diphenyl isooctyl phosphite, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate are 64 mL, 12 mL, and 4 mL, respectively. The mass of the ethyl cellulose is 1.92 g.

[0065] The organic solvent was composed of 20 mL of ethyl acetate, 20 mL of acetone and 20 mL of n-butanol reagent.

[0066] In this embodiment, the preparation method of the paper pastel pencil handwriting revealing reinforcing agent is referred to Example 1.

[0067] Comparative Example

[0068] The visualization reinforcing agent provided in this comparative example is formed from ethyl cellulose, an organic solvent, and diphenyl isooctyl phosphite.

[0069] Preferably, the volumes of the organic solvent and diphenyl 2-isooctyl phosphite are 60 mL and 12 mL, respectively. The mass of the ethyl cellulose is 1.8 g. The organic solvent is composed of 20 mL of ethyl acetate, 20 mL of acetone, and 20 mL of n-butanol reagent.

[0070] The preparation method of the visualization reinforcing agent in this comparative example refers to Example 1.

[0071] Furthermore, the performance of the revealing reinforcement agents in the above examples and comparative examples in protecting pastel pencil writing on engineering blueprints was studied.

[0072] In the performance study, the blueprint paper was reinforced to obtain paper powder simulation samples. The specific reinforcement process is as follows: several samples to be reinforced were cut from the same engineering blueprint paper and divided into three groups, with multiple samples in each group;

[0073] Group 1: one as an unreinforced sample;

[0074] The second group: the surface of each sample to be reinforced with pastel pencil writing was evenly coated with the color-developing reinforcing agent of Example 1, which was recorded as the reinforced sample of the experimental group;

[0075] The third group: The surface of the pastel pencil writing on each sample to be reinforced is evenly coated with the color-developing reinforcement agent of the comparative example, and is recorded as the reinforced sample of the control group.

[0076] The samples obtained from the above three groups are paper powder simulation samples, and then performance tests are carried out.

[0077] In the performance study, the damp heat accelerated aging method was used in accordance with GB / 22894-2008. Aging conditions were set at 80°C, 65% humidity, and 72 hours. After the damp heat accelerated aging, the samples were removed and allowed to equilibrate in an indoor environment for one day.

[0078] In the performance study, the UV accelerated aging was carried out according to GB / T 40278-2021 Accelerated aging of paper and paperboard (under light conditions); the wavelength range was set to 290-800nm, and the power was 20W / m 2 The irradiance was 200 mm at a vertical distance of 200 mm, the temperature was maintained at 25°C, and the aging time was 3 days. After the UV accelerated aging, the samples were taken out and allowed to balance in the indoor environment for one day.

[0079] The performance test analysis of the paper powder simulation sample is as follows.

[0080] Test 1: Reflectivity

[0081] The unreinforced samples, the reinforced samples of the experimental group, and the reinforced samples of the control group were used as the test samples and subjected to damp heat accelerated aging and UV accelerated aging pretreatment respectively. Then, the reflectivity of the test samples was tested using a UV-Lambda950 ultraviolet near-infrared spectrophotometer in the wavelength range of 250-800nm ​​and a scanning rate of 300nm / min; the results are as follows: Figure 1 and Figure 2 shown.

[0082] Figure 1 Reflectivity curves of unreinforced samples and reinforced samples of the experimental group under different treatments; Figure 1 Figures a and b show the results for the unreinforced sample and the reinforced experimental sample before aging, respectively. The unreinforced sample's reflectance fluctuates significantly, ranging from 15.25% at 550nm to 58.33% at 700nm, with generally higher values. The reinforced experimental sample's reflectance decreases and becomes more stable overall, reaching 10.06% at 550nm and 23.20% at 700nm. This is because the rough surface of the pastel pencil powder particles in the unreinforced sample leads to severe light scattering, resulting in an increase in reflectance with increasing wavelength and blurred color rendering. In contrast, the ethyl cellulose in the reinforced experimental sample forms a film, filling the gaps between the pastel pencil powder particles, reducing surface roughness and suppressing light scattering, resulting in a lower and more stable reflectance. Figures c and d show the unreinforced sample and the reinforced sample from the experimental group after hygrothermal aging; and figures e and f show the unreinforced sample and the reinforced sample from the experimental group after UV aging. It can be seen that the reflectivity of the unreinforced sample after aging fluctuates significantly and is generally higher, while the reflectivity of the reinforced sample from the experimental group decreases and is more gradual. This demonstrates that the development reinforcement agent of Example 1 can reduce surface roughness and inhibit light scattering, while the antioxidant and light stabilizer work synergistically to maintain color stability.

[0083] Figure 2 is the reflectivity curve of the control group reinforced sample under different treatments; where dp is the control group reinforced sample, dpsr is the control group reinforced sample after wet heat aging, and dpzw is the control group reinforced sample after UV aging.

[0084] from Figure 2It can be seen that the absorption of the dp curve in the blue-violet band is enhanced. Since GW-508 originally has an optical brightening or dispersing effect, its absence causes the ultraviolet absorption characteristics of the film-forming material (such as resin) to emerge. After ultraviolet aging, the reflectivity in the visible light band (380-780nm) increases abnormally, and the reflectivity at 800nm ​​is 376.07%, which deviates seriously from the normal value, indicating that the material structure is damaged by aging. After aging, the reflectivity in the visible light band increases to over 100%, seriously reducing the visibility of light-colored writing. The reflectivity in the short-wave band fluctuates violently after aging, indicating that the resin-filler interface has aged and cracked due to the lack of GW-508 light stabilizer, and the material surface has become powdery, resulting in enhanced light scattering, thereby reducing the adhesion of the pastel pencil writing powder and accelerating the peeling of the coating.

[0085] comprehensive Figure 1 and Figure 2 It can be seen that the three raw materials in the color-developing reinforcing agent of this embodiment work synergistically to effectively inhibit light scattering, maintain color stability, and enhance the adhesion of the pastel pencil writing powder, making it less likely to fall off due to friction and aging during storage.

[0086] Test 2: Glossiness

[0087] Unreinforced samples, reinforced experimental samples, and reinforced control samples were used as test samples and subjected to both damp-heat accelerated aging and UV-accelerated aging pretreatments. Following treatment, the test samples were equilibrated at 23±3°C and a relative humidity of 40% to 60% for 24 hours according to GB / T8941-2013, "Paper and paperboard — Determination of specular gloss." The gloss was then measured at five different points on the test samples using a GM-247 gloss meter at incident angles of 20°, 45°, and 75°. The results are shown in Table 1.

[0088] Table 1 Glossiness of samples

[0089] 20° 45° 75° a 5.8 3.0 3.9 b 4.9 2.1 3.5 c 5.0 2.2 2.7 d 4.8 2.0 2.5 e 5.5 2.9 2.7 f 5.0 2.5 2.5 dp 4.7 1.6 3.7 dpsr 4.6 1.7 3.5 dpzw 4.8 1.8 3.8

[0090] Among them: a is the unaged unreinforced sample, b is the unaged experimental group reinforced sample, c is the unreinforced sample treated with hygrothermal aging, d is the reinforced sample of the experimental group treated with hygrothermal aging, e is the unreinforced sample treated with UV aging, and f is the reinforced sample of the experimental group treated with UV aging; dp is the unaged control group reinforced sample, dpsr is the control group reinforced sample after hygrothermal aging, and dpzw is the control group reinforced sample after UV aging.

[0091] Under unaged conditions, the glossiness of the unreinforced sample at an incident angle of 20° was 5.8, while the glossiness of the reinforced sample in the experimental group was 4.9. The glossiness of the unreinforced sample at an incident angle of 45° was 3.0, while the glossiness of the reinforced sample in the experimental group was 2.1. The glossiness of the unreinforced sample at an incident angle of 75° was 3.9, while the glossiness of the reinforced sample in the experimental group was 3.5. After reinforcement with the color-developing reinforcing agent of this embodiment, the glossiness at different incident angles decreased. This is because the ethyl cellulose film fills the gaps between the particles, reduces surface roughness, and inhibits light scattering, resulting in reduced specular reflection and lower glossiness.

[0092] After hygrothermal aging, the gloss of the unreinforced sample at an incident angle of 20° was 5.0, while the gloss of the reinforced sample in the experimental group was 4.8. At an incident angle of 45°, the gloss of the unreinforced sample dropped from 3.0 to 2.2, a 26.7% decrease in gloss, while the gloss of the reinforced sample in the experimental group dropped from 2.1 to 2.0, a 4.8% decrease in gloss. This indicates that the developer significantly inhibits the gloss loss caused by hygrothermal aging, indicating that its hydrophobic film protects the particles from moisture erosion. At the same time, at an incident angle of 75°, the gloss of the reinforced sample in the experimental group dropped from 3.5 (unaged) to 2.5, close to the gloss of 2.7 of the unreinforced sample after hygrothermal aging, indicating that hygrothermal aging has little effect on the film.

[0093] After UV aging treatment, at an incident angle of 45°, the gloss of the unreinforced sample dropped from 2.9 to 2.5, a 13.8% decrease. The gloss of the reinforced sample in the experimental group remained stable, demonstrating that the color-developing agent effectively inhibits color degradation caused by UV aging.

[0094] The glossiness of the DPSR sample at a 75° angle was 3.5, lower than the 3.7 of the unaged DP sample. However, compared to the reinforced sample in the experimental group, its UV resistance decreased by 16.7%. The glossiness of the DPSR sample at a 45° angle was 1.8, close to the 1.6 of the unaged DP sample. This indicates that the DPOP in the comparative example alone can maintain thermal stability, but the performance of the color-developing reinforcement in the comparative example is significantly reduced under UV aging conditions: the glossiness at a 45° angle decreased by 32%, and the color clarity was impaired. The reflectance at 75° increased by 16.7%, indicating increased surface light scattering.

[0095] Therefore, when GW-508 is added to the color-developing reinforcing agent as a light stabilizer, the three raw materials work synergistically to maintain long-term optical stability, which can maximize the suppression of light scattering during ultraviolet aging, ensure clear handwriting, effectively prevent the color fading of colored pencil handwriting caused by aging, and achieve color reinforcement.

[0096] Test 3, laser confocal

[0097] Unreinforced samples, reinforced samples in the experimental group, and reinforced samples in the control group were used as test samples and subjected to damp-heat accelerated aging and UV accelerated aging pretreatments, respectively. A VK-X250 laser confocal microscope was then used to analyze the surface morphology of the samples before and after reinforcement and aging. Under conditions of an excitation wavelength of 405 nm and an objective magnification of 20×, the sample surface was scanned at a resolution of 512×512 pixels to obtain three-dimensional morphological data and surface roughness parameters (Sa, Sz). By comparing the microstructural characteristics of the samples before and after reinforcement and before and after different aging treatments, a quantitative evaluation of the regulation of the sample surface morphology was performed. The analysis results are shown in Figure 2. Figure 3 and Figure 4 shown.

[0098] Figure 3 In the data, the Sa (arithmetic mean height) was 2.705 μm for the unreinforced sample under unaged conditions, while the Sa of the reinforced sample in the experimental group decreased to 2.562 μm (a decrease of 5.3%). After wet-heat aging, the Sa of the unreinforced sample was 2.578 μm, while the Sa of the reinforced sample in the experimental group decreased to 2.043 μm (a decrease of 20.8%). After UV aging, the Sa of the reinforced sample in the experimental group further decreased to 1.201 μm. This indicates that ethyl cellulose film formation significantly reduces surface roughness, especially under wet-heat and UV aging conditions.

[0099] Figure 3 Regarding Sz (maximum height): After UV aging, the Sz of the unreinforced sample was 52.443 μm, while the Sz of the reinforced sample in the experimental group decreased to 23.174 μm (a decrease of 55.8%). This indicates that the visual reinforcement suppresses extreme surface fluctuations, protecting the pastel pencil writing from environmental stress damage.

[0100] Figure 3 Regarding Str (surface texture aspect ratio): under unaged conditions, the Str of the unreinforced sample was 0.872, while the Str of the reinforced sample in the experimental group increased to 0.883 (closer to 1), indicating that the surface texture is more uniform and isotropy is enhanced after film formation. The closer the Str value is to 1, the more uniform the surface texture, the less light scattering, and the higher the color clarity. This shows that the color-developing reinforcement agent of Example 1 significantly improves optical performance by reducing surface directionality (increasing the Str value).

[0101] Figure 3Regarding Sdr (surface development area ratio): under unaged conditions, the Sdr of the unreinforced sample was 0.5521, while the Sdr of the reinforced sample in the experimental group decreased to 0.352 (a decrease of 36.2%). After hygrothermal aging, the Sdr of the unreinforced sample was 0.3951, while the Sdr of the reinforced sample in the experimental group decreased to 0.2021 (a decrease of 48.8%). This indicates that the color-developing reinforcing agent of Example 1 significantly simplifies the surface microstructure, reduces light scattering caused by complex morphology, and improves color clarity.

[0102] From the above analysis, it can be seen that after wet heat aging treatment, the Sa, Sz, and Sdr of the reinforced samples in the experimental group are significantly lower than those of the unreinforced samples, indicating that the hydrophobic film layer effectively inhibits humidity erosion. After ultraviolet aging treatment, the Sa (1.021μm), Sz (23.174μm), and Sdr (0.139) of the reinforced samples in the experimental group are much lower than those of the unreinforced samples, verifying the synergistic anti-aging effect of the light stabilizer and antioxidant. This shows that the visual reinforcement agent of Example 1 can significantly reduce surface roughness and complexity, inhibit light scattering, and improve color clarity. It is stable under wet heat and ultraviolet aging conditions, proving that the reinforcement effect of the visual reinforcement agent is durable.

[0103] Figure 4 In the figure, dp is the unaged control group reinforced sample, dpsr is the control group reinforced sample after wet heat aging, and dpzw is the control group reinforced sample after UV aging.

[0104] from Figure 4It can be seen that the surface roughness (Sa) increased, with the dpzw surface roughness increasing by 10.3% and the dpsr surface roughness increasing by 34%. It can be seen that the absence of GW-508 leads to a decrease in the resin-filler interface bonding strength, and after aging, the resin shrinks and cracks, making the surface rougher. The rough surface scatters light, reducing the contrast between the handwriting and the background, especially affecting the recognition of light-colored pastel pencils. After UV aging, the maximum height (Sz) of the reinforced sample in the control group increased by 21.7%, indicating the appearance of local ridges and deep grooves on the surface. This is because the light stabilizer GW-508 was not added to the control example, causing the filler to agglomerate, and local stress concentration after UV irradiation formed ridges. The raised areas accelerate the friction and shedding of the handwriting, while the deep grooves are prone to dust accumulation and contamination of the handwriting. After hygrothermal aging, the surface texture aspect ratio (Str) of the control reinforced sample became disordered, decreasing from 0.735 to 0.603 (approaching 0 indicates complete disorder). This indicates that after hygrothermal aging, the surface texture of the control reinforced sample lost its directional texture and became random cracks. These cracks destroyed the integrity of the writing and increased pencil powder shedding. After hygrothermal aging, the surface development area ratio (Sdr) of the control reinforced sample soared from 0.3675% to 0.8496%, indicating the formation of a large number of microcracks and voids. It can be seen that the lack of GW-508 in the color-developing reinforcement in the comparative example increased the surface roughness (Sa) after UV aging, weakening the optical contrast and increasing the maximum height (Sz), accelerating the physical wear of the writing. The texture disorder and the surge in the surface development area ratio after hygrothermal aging led to the shedding and contamination of the writing, and the increased roughness and peak density further reduced visibility.

[0105] Test 4: Infrared spectroscopy

[0106] The unreinforced samples, the reinforced samples of the experimental group and the reinforced samples of the control group were used as the test samples and were subjected to damp heat accelerated aging and ultraviolet accelerated aging pretreatment respectively. The treated samples were then analyzed by PE-Frontier mid-infrared-far infrared spectrometer at 400-4000cm -1 The infrared spectrum of the sample is measured within the range of Figure 5 shown.

[0107] Figure 5 In the figure, a and b are infrared spectra of the unreinforced sample and the reinforced sample of the experimental group without aging. It can be seen that the peak positions of Example 1 before and after application of the reinforcing agent are basically the same, the absorption peak intensity has changed, and no new functional groups have been generated. This shows that the reinforcing agent itself does not react with the powder sample on the paper and will not have any impact on the printed paper, which is in line with the principle of cultural relic protection of printed paper. -1 The absorption peak at 2900 cm is the OH stretching vibration peak. -1 The absorption peak at 1740 cm is the stretching vibration of CH and CH2 in the molecule.-1 The absorption peak at 1434 cm is the C=O stretching vibration peak. -1 and 1372cm -1 The absorption peak at 1020 cm is the bending vibration peak of methylene. -1 The absorption peak at 880 cm is the stretching vibration peak of CO. -1 917cm -1 The absorption peak is caused by the vibration absorption peak of the OC2H3 functional group of ethyl cellulose.

[0108] c, d are the infrared spectra of the unreinforced sample and the reinforced sample of the experimental group after wet heat aging; e, f are the infrared spectra of the unreinforced sample and the reinforced sample of the experimental group after UV aging. It can be seen that: there is no obvious change in the peak position, 3400cm -1 ~3300cm -1 The peak intensity of the OH stretching vibration peak is lower in the powder sample reinforced with the color-developing reinforcement agent than in the unreinforced powder sample, indicating that the fiber bonding strength of the solar-printed paper is minimally reduced after treatment with the color-developing reinforcement agent, and the durability is maintained well. Therefore, when the color-developing reinforcement agent of Example 1 is applied to the pastel pencil writing on the engineering solar-printed paper, it can ensure that the writing is minimally affected in high temperature and high humidity environments, protecting the pastel pencil writing on the engineering solar-printed paper from damage to the greatest extent, thereby achieving the purpose of color-developing reinforcement.

[0109] Figure 6 The infrared spectrum of the control group reinforced sample is shown in Figure 1, where dp is the unaged control group reinforced sample, dpsr is the control group reinforced sample after wet heat aging, and dpzw is the control group reinforced sample after UV aging. It can be seen that after UV aging, the control group reinforced sample has a high infrared spectroscopy at 1720 cm -1 The newly generated carbonyl peak at 3300 cm -1 The hydroxyl peak at 1050 cm is enhanced and broadened, which leads to the accumulation of oxidation by-products, which causes the coating to become brittle and peel off, and the writing is directly exposed to the environment. -1 The Si-O-Si peak at 1150cm-1 is broken, which causes hydrolysis at the filler and resin interface. -1 The COC peak weakens at 2920 cm, causing the resin ether bond to break, which leads to interfacial debonding and the formation of microcrack networks; -1 The CH peak intensity decreases at 600-800 cm -1 The increase in impurity peaks (in the fingerprint area) is due to the accumulation of small molecular degradation products. It can be seen that the use of the comparative color-developing reinforcing agent for reinforcement will lead to an increase in surface energy, which accelerates the adsorption of dust and covers the writing.

[0110] Through the above analysis, the use of the color-developing reinforcing agent in the comparative example will cause the chemical structure to collapse, resulting in the complete failure of the handwriting protection function after aging; however, the use of the color-developing reinforcing agent in Example 1 can avoid the impact on the printed drawing in a high temperature and high humidity environment, ensure the integrity of the pastel pencil handwriting, and will not fade after aging.

[0111] Test 5: Water contact angle measurement on paper surface

[0112] The unreinforced samples and the reinforced samples of the experimental group were used as the test samples and subjected to wet heat accelerated aging and UV accelerated aging pretreatment respectively. Then, according to TappiT558om-2 "Surface Wettability and Absorbency of Sheeted Materials Using an Automated Contact Angle Tester", the static contact angle of the paper before and after wet heat accelerated aging was measured using the sessile drop method in the video optical contact angle tester. A long paper sample was cut and placed on the sample table. Then, 2 microliters of deionized water was dropped on the surface of the writing powder on the paper. The appropriate light intensity was adjusted and the lower droplet surface of the water drop was quickly photographed with a camera. After automatic fitting calculation by the computer, the static contact angle value of the sample was obtained. 10 groups of measurements were taken for each sample and the average value was taken. The results are shown as follows: Figure 7 and Figure 8 shown.

[0113] Figure 7 is the contact angle of the sample, Figure 8 is the change of contact angle with time; wherein: a is the unaged unreinforced sample, b is the unaged reinforced sample of the experimental group, and it can be seen that after applying the color-developing reinforcement agent, the contact angle increased by 53.15°. c is the unreinforced sample after wet-heat aging, d is the reinforced sample of the experimental group after wet-heat aging, and it can be seen that after applying the color-developing reinforcement agent, the contact angle increased by 29.53° after wet-heat aging treatment. e is the unreinforced sample after UV aging, and f is the reinforced sample of the experimental group after UV aging, and it can be seen that after applying the color-developing reinforcement agent, the contact angle increased by 38.79° after UV aging treatment. It can be seen that after reinforcement with the color-developing reinforcement agent of Example 1, the contact angle is greater than that of the unreinforced sample, indicating that applying the color-developing reinforcement agent of Example 1 can improve the hydrophobicity of the powder and prevent the paper pastel lead writing on the drying drawing from absorbing water and falling off.

[0114] Test 6: Powder pulverization degree

[0115] The chalking grade was assessed using the tape method in GB / T 30789, "Evaluation of aging of paints and varnishes - Number and size of defects and identification of uniform changes in appearance". Powder was removed from the coating of the paper sample before and after reinforcement using tape. The powder adhered to the tape was inspected against a black background. The chalking grade was assessed using the grade rating table. The results were as follows: Figure 9 shown.

[0116] See also Figure 9 1 is the powder of the unreinforced sample, with a visually observed powdering grade of 4; 2 is the powder of the reinforced sample in the experimental group, with a visually observed powdering grade of 2. A higher powdering grade indicates weaker adhesion and greater ease of shedding. This indicates that applying the color-developing reinforcement agent of Example 1 improves the adhesion between the powder and the printing paper, preventing the powder from falling off the paper and enhancing the reinforcement performance.

[0117] The above performance tests were all conducted on the color-developing reinforcing agent of Example 1. The color-developing reinforcing agents prepared using the parameters of Example 2, Example 3, or those within the specified range of the present invention also exhibited the same or similar performance, and had excellent anti-hydrophilicity, making the pastel pencil writing difficult to fall off; it also had the effect of inhibiting light scattering, which could improve the color clarity of the writing, making the pastel pencil writing not easy to age and fade, and was beneficial to the long-term preservation of the printing paper.

[0118] The above are several relatively preferred implementation methods of the preparation method of the present invention, but they cannot be used as limitations on the technical solutions protected by the present invention. Any replacement solutions obtained by ordinary technicians in this field without making creative work based on the technical ideas of the present invention should fall within the scope of protection of the present invention.

Claims

1. A paper pastel pencil handwriting enhancement agent, characterized in that: It is formed from ethyl cellulose, an organic solvent, diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate; The volume ratio of the organic solvent, diphenyl 2-isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate is (14-16):(2-3):1; Add 2g to 3g of ethyl cellulose to every 100mL of organic solvent.

2. The paper pastel pencil handwriting enhancement agent according to claim 1, characterized in that: The organic solvent is prepared by mixing equal volumes of ethyl acetate, acetone and n-butanol.

3. The paper pastel pencil handwriting enhancement agent according to claim 1, characterized in that: The water contact angle of the paper reinforced with pastel pencil writing showed by the reinforcer increased by 53.15°.

4. The paper pastel pencil handwriting enhancement agent according to claim 1, characterized in that: The emissivity of the reinforcing agent for revealing pastel pencil writing on paper is 10.06% at a wavelength of 550nm and 23.20% at a wavelength of 700nm.

5. The paper pastel pencil handwriting enhancement agent according to claim 1, characterized in that: The glossiness of the paper pastel pencil writing enhancer at incident angles of 20°, 45° and 75° before aging was 4.9, 2.1 and 3.5 respectively; after aging, the glossiness at incident angles of 20°, 45° and 75° was the lowest at 4.8, 2.0 and 2.5 respectively.

6. A method for preparing the paper pastel pencil handwriting enhancement agent according to claim 1, characterized in that: The following steps are involved: S1. Mixing ethyl cellulose and an organic solvent, stirring uniformly in a water bath using a condensation reflux method until the ethyl cellulose is completely dissolved, to obtain an ethyl cellulose solution; S2. Continue to add diphenyl isooctyl phosphite and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate to the ethyl cellulose solution respectively, stir evenly, and obtain a paper pastel pencil handwriting visualization and reinforcement agent.

7. The preparation method according to claim 6, characterized in that In step S1, the temperature of the water bath is 45° C. to 55° C., and the stirring speed is 300 rpm to 400 rpm.

8. The preparation method according to claim 6, characterized in that In step S2, the stirring time is 10 min to 15 min, and the stirring temperature is 45° C. to 55° C.

9. Use of the paper pastel pencil writing reinforcing agent according to claim 1 in preventing paper pastel pencil writing from falling off on engineering blueprints.

10. Use of the paper pastel pencil writing reinforcing agent according to claim 1 in preventing the aging and fading of paper pastel pencil writing on engineering blueprints.

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