Neutral ink ballpoint pen follow-up sealant and preparation method thereof

Abstract

The invention relates to a gel ink ballpoint pen follow-up sealant using a modified SEEPS-OH elastomer as a thickening agent and a preparation method of the gel ink ballpoint pen follow-up sealant. A polar group modified SEEPS-OH elastomer is adopted as a thickening agent of the follow-up sealant, the affinity with ink is properly improved while the stability of a grease system is not damaged, and the polar group of the SEEPS-OH modified elastomer weakens the affinity between the follow-up sealant and the inner wall of a refill oil tube. Under the combined action of the two, the follow-up sealant has good follow-up performance. The polar groups of the end group of the modified SEEPS-OH elastomer are distributed in a dotted mode on the inner wall of the oil pipe, the affinity of the follow-up sealant and the whole oil pipe is not damaged, good follow-up performance is achieved, meanwhile, the anti-falling performance is guaranteed, and the contradictory problem of the anti-falling performance and the follow-up performance is solved.

Description

Technical Field

[0001] The invention relates to a neutral ink ballpoint pen follower sealant using a modified SEEPS-OH elastomer as a thickener, and a preparation method of the follower sealant. Background Art

[0002] Follow-up sealant (also called tail plug oil) is an indispensable material for the manufacture of neutral ink ballpoint pens. It is used to seal the ink at the tail of the pen tube to prevent the ink from flowing back or volatilizing. A good follow-up sealant not only has a sealing function, but also should have good follow-up mobility, which can ensure that it can follow up and move down in time when writing quickly, and a small amount of it should stick to the tube wall to ensure that there is still a follow-up sealant left to play a sealing role when the ink is completely used up; the follow-up sealant should also have good anti-fall properties, and under vibration conditions such as the drop of the neutral ink ballpoint pen, the ink in the pen core will not fall out or leak. Follow-up sealants are usually composed of base oil, thickener, structure improver (also called stabilizer), and other functional additives. The base oil can be mineral oil, silicone oil, polyolefin, etc. The thickener can be lithium soap, calcium salt of phosphate ester, fumed silica, block copolymer of polystyrene-polyethylene / butylene rubber-polystyrene, etc. or a mixture of the above. The structure improver is used to adjust the structure of the follow-up sealant to improve stability. Other functional additives include antioxidants, viscosity improvers, etc.

[0003] Fumed silica is one of the commonly used thickeners for preparing follow-up sealants. Since a large number of hydroxyl groups are easily present on the surface of fumed silica and its compatibility with base oil is poor, the surface of fumed silica must be modified. Patent ZL20211585048.X uses silane coupling agent to modify nano-SiO2 as a thickener. The coupling agent can chemically bond with the surface of nano-SiO2 particles to form a large steric hindrance, blocking the agglomeration between nano-SiO2 particles, effectively improving the compatibility of nano-SiO2 with organic media, and improving its dispersion stability in organic media. Patent CN 118580687A (publication number) first uses a silane coupling agent to modify the surface of nano-SiO2 particles, and then uses an emulsification reaction to modify long-chain carboxylic acids to obtain amphiphilic Janus modified silica nanoparticles. The follow-up sealant prepared using amphiphilic Janus modified silica nanoparticles can seal while avoiding miscibility with neutral ink. Patent ZL202111367362.0 discloses a stabilizer-modified neutral ink ballpoint pen follower sealant, which contains a hydrophilic active group and an oleophilic carbon-carbon long chain. The active group in the stabilizer can be connected to the fumed silica in the follower sealant, and the carbon-carbon long chain can be connected to the base oil in the follower sealant, making the follower sealant more stable. It can be seen that how to improve the stability of the follower sealant and avoid miscibility with neutral ink is one of the key technologies of the follower sealant.

[0004] Patent CN 1615228A (publication number) provides an ink follower for water-based ink ballpoint pens, and the oil separation value of the ink follower is required to be 0.5-12% (60°C, 24h). The patent points out that if the oil separation is less than 0.5%, there is no satisfactory followability; if the oil separation is greater than 12%, the base oil easily migrates into the ink, causing a deteriorated appearance and poor writing. It can be seen that the followability of the follower sealant is also a key technology.

[0005] Improving the follow-up performance requires reducing the affinity between the follow-up sealant and the oil pipe or reducing the viscosity to increase the fluidity. However, the reduction in the affinity between the follow-up sealant and the oil pipe or the increase in fluidity will damage its anti-fall performance to a certain extent. It can be seen that there is a certain contradiction between follow-up performance and anti-fall performance. The follow-up sealant is required to be miscible with the ink, otherwise the components in the follow-up sealant will migrate into the ink to damage the writing performance, or the components in the ink will migrate into the follow-up sealant to damage its performance. However, the follow-up sealant and the ink are required to have a certain affinity. This is because if the follow-up sealant lacks affinity with the ink, it is easy to produce a fault with the ink when it is poured into the pen core. When writing, it cannot move down as the ink is consumed, and the follow-up performance is poor.

[0006] The neutral ink ballpoint pen follower sealant disclosed in the current patent technology still has certain problems in terms of follow-up, drop resistance and stability, or the technical solutions adopted are relatively complex, the production cost is high, and it is difficult to mass produce. Summary of the invention

[0007] The present invention aims to overcome the deficiencies of the prior art and provide a neutral ink ballpoint pen follower sealant with excellent followability and drop resistance and a preparation method thereof.

[0008] The object of the present invention is achieved through the following solutions:

[0009] A neutral ink ballpoint pen follower sealant comprises, by weight, 19 to 40 parts of base oil, 5 to 10 parts of plasticizer, 0.2 to 0.5 parts of antioxidant and 50 to 75 parts of thickener.

[0010] The thickener is prepared by ethoxy-modifying SEEPS-OH elastomer in the base oil.

[0011] The structural formula of SEEPS-OH elastomer is as follows:

[0012]

[0013] The weight average molecular weight of the SEEPS-OH elastomer is 20,000 to 40,000, wherein i, j, k, m, and n are all integers greater than 0.

[0014] The structural formula of SEEPS-OH elastomer modified by ethoxy is as follows:

[0015]

[0016] Here, p is an integer greater than 0.

[0017] The content of ethoxy groups in the ethoxy-modified SEEPS-OH elastomer is 0.2-0.4 mol / kg.

[0018] When the content of ethoxy in the ethoxy-modified SEEPS-OH elastomer is less than 0.2 mol / kg, the affinity of the thickener to the inner wall of the oil tube of the pen core and the ink does not change significantly, and the follow-up sealant prepared with this thickener fails to achieve improved follow-up performance. When the content of ethoxy in the ethoxy-modified SEEPS-OH elastomer is greater than 0.4 mol / kg, the hydrophilicity of the thickener is increased so significantly that the base oil is obviously precipitated after being added to the base oil and stored, which is manifested as ink channeling.

[0019] The base oil is one of mineral oil, dimethyl silicone oil and polyalphaolefin (PAO).

[0020] The plasticizer is one of ethyl rubber, propyl rubber, butyl rubber, phenyl silicone rubber and styrene-butadiene rubber.

[0021] The antioxidant is one of butylated hydroxybenzoic acid and tri-tert-butylated hydroxyanisole.

[0022] The viscosity of the follow-up sealant is 30000-50000 cp at a rotation speed of 6 rpm using a No. 4 rotor of a rotational viscometer.

[0023] The preparation method of the follower sealant of the present invention comprises the following steps:

[0024] Thickener preparation

[0025] The SEEPS-OH elastomer particles are dispersed in a base oil at 110-120° C., 0.2% of the total mass of KOH powder is added as a catalyst, replaced with dry nitrogen three times, dehydrated at 110-120° C. and -0.07--0.09 MPa for 20-30 min, heated to 140-150° C., ethylene oxide is introduced, and the pressure in the reactor is maintained at ≤0.4 MPa. When the pressure in the reactor remains unchanged, nitrogen is introduced, and the reaction is completed. Activated carbon is added and stirred for 30 min to adsorb the potassium hydroxide catalyst, and the activated carbon adsorbed with potassium hydroxide is removed by hot filtration, and the temperature is lowered to obtain a mixture of the base oil and the ethoxy-modified SEEPS-OH dispersed in the base oil, which is a thickener;

[0026] (2) Preparation of follow-up sealant

[0027] Add thickener to base oil, raise the temperature to 130-170°C, stir at constant temperature for 30-90 minutes after the temperature reaches the target value, transfer to high-speed disperser, disperse at 5000-8000rpm for 30-60 minutes, add plasticizer, continue high-speed dispersion for 30-60 minutes, add antioxidant, and disperse at high speed for another 20-40 minutes. Stop high-speed dispersion and cool to room temperature. Store in vacuum drying oven for 48 hours for defoaming to obtain follow-up sealant.

[0028] Compared with the prior art, the follower sealant of the present invention has the following advantages:

[0029] The polar group-modified SEEPS-OH elastomer is used as a thickener for the follower sealant, which does not damage the stability of the grease system while moderately improving the affinity with the ink. The follower sealant can follow and move down in time during the writing process. The polar group of the modified SEEPS-OH elastomer weakens the affinity between the follower sealant and the inner wall of the oil pipe of the pen core. Under the joint action of the two, the follower sealant of the present invention has good followability.

[0030] The modified SEEPS-OH elastomer is evenly distributed in the follow-up sealant, and the polar groups at the end of the modified SEEPS-OH elastomer are distributed in a dotted manner on the inner wall of the oil pipe, which does not damage the overall affinity between the follow-up sealant and the oil pipe, achieves good follow-up performance while ensuring anti-fall performance, and solves the contradictory problem between anti-fall performance and follow-up performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic diagram of the interaction between the follow-up sealant and the inner wall of the oil tube of the pen core and the ink. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below according to specific embodiments. The protection scope of the present invention is not limited to the following embodiments, which are listed only for illustrative purposes and do not limit the present invention in any way.

[0033] Example 1

[0034] The preparation of the follow-up sealant in this embodiment includes the following steps:

[0035] (1) Preparation of thickener

[0036] 4000g of mineral oil was added to a reactor, and the temperature was raised to 110°C. 991.19g of SEEPS-OH elastomer particles (weight average molecular weight 20000) were added under stirring to make them uniformly dispersed, and then 10g of KOH powder was added as a catalyst, and the mixture was replaced with dry nitrogen for 3 times. The mixture was dehydrated at 120°C and -0.07MPa, and the temperature was raised to 140°C. 8.81g of ethylene oxide was introduced to keep the pressure in the reactor ≤0.4MPa. When the pressure in the reactor remained unchanged, nitrogen was replaced, and the reaction was completed. 200g of activated carbon was added and stirred for 30min to adsorb potassium hydroxide catalyst, and the activated carbon adsorbed with potassium hydroxide was removed by filtering while hot, and the temperature was lowered to obtain a mixture of base oil and ethoxy-modified SEEPS-OH dispersed in the base oil, which was a thickener. The ethoxy content in the obtained ethoxy-modified SEEPS-OH elastomer was 0.2mol / kg.

[0037] (2) Preparation of follow-up sealant

[0038] Add 50.0 g of the thickener prepared in step (1) to 39.8 g of mineral oil, heat to 130° C., stir at constant temperature for 90 min, transfer to a high-speed disperser, and disperse at high speed at 5000 rpm for 60 min. Add 10.0 g of plasticizer ethyl rubber, continue to disperse at high speed for 45 min, add 0.2 g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40 min. Stop dispersing and cool to room temperature. Store in a vacuum drying oven for 48 h to defoam, and obtain a follow-up sealant.

[0039] Example 2

[0040] The preparation of the follow-up sealant in this embodiment includes the following steps:

[0041] (1) Preparation of thickener

[0042] 8000g of dimethyl silicone oil was added to a reactor, the temperature was raised to 120°C, 1973.57g of SEEPS-OH elastomer particles (weight average molecular weight 40000) were added under stirring to make them uniformly dispersed, 20g of KOH powder was added as a catalyst, the mixture was replaced with dry nitrogen three times, dehydrated at 120°C and -0.09MPa, the temperature was raised to 145°C, 26.43g of ethylene oxide was introduced, the pressure in the reactor was kept ≤0.4MPa, the pressure in the reactor was kept constant, nitrogen was replaced, the reaction was completed, 400g of activated carbon adsorbed potassium hydroxide catalyst was added, the activated carbon adsorbed with potassium hydroxide was removed by hot filtration, the temperature was lowered, and a mixture of base oil and ethoxy-modified SEEPS-OH dispersed in the base oil was obtained, which was a thickener; the ethoxy content in the obtained ethoxy-modified SEEPS-OH elastomer was 0.3mol / kg;

[0043] (2) Preparation of follow-up sealant

[0044] Add 60.0 g of the thickener prepared in step (1) to 31.8 g of dimethyl silicone oil, heat to 170° C., stir at constant temperature for 30 min, transfer to a high-speed disperser, and disperse at high speed at 6500 rpm for 45 min. Add 8.0 g of plasticizer butyl rubber, continue to disperse at high speed for 30 min, add 0.2 g of antioxidant tri-tert-butyl hydroxyanisole, and disperse at high speed for another 20 min. Stop dispersing and cool to room temperature. Store in a vacuum drying oven for 48 h to defoam, and obtain a follow-up sealant.

[0045] Example 3

[0046] The preparation of the follow-up sealant in this embodiment includes the following steps:

[0047] (1) Preparation of thickener

[0048] 6000g of polyalphaolefin (PAO 10) was added to a reactor, the temperature was raised to 120°C, 1473.57g of SEEPS-OH elastomer particles (weight average molecular weight 30000) were added under stirring to make them uniformly dispersed, 15g of KOH powder was added as a catalyst, the mixture was replaced with dry nitrogen for 3 times, dehydrated at 110°C and -0.09MPa, the temperature was raised to 150°C, 26.43g of ethylene oxide was introduced, the pressure in the reactor was kept ≤0.4MPa, nitrogen was replaced until the pressure in the reactor remained unchanged, the reaction was completed, 300g of activated carbon adsorbed potassium hydroxide catalyst was added, the activated carbon adsorbed with potassium hydroxide was removed by hot filtration, the temperature was lowered, and a mixture of base oil and ethoxy-modified SEEPS-OH dispersed in the base oil was obtained, which was a thickener; the ethoxy content in the obtained ethoxy-modified SEEPS-OH elastomer was 0.4mol / kg;

[0049] (2) Preparation of follow-up sealant

[0050] 75.0 g of the thickener prepared in step (1) was added to 19.5 g of polyalphaolefin (PAO 10), the temperature was raised to 150° C., and the mixture was stirred at a constant temperature for 60 min. The mixture was then transferred to a high-speed disperser and dispersed at a speed of 8000 rpm for 30 min. 5.0 g of plasticizer styrene-butadiene rubber was added and the high-speed dispersion was continued for 60 min. 0.5 g of antioxidant tri-tert-butylhydroxyanisole was added and the mixture was dispersed at a high speed for another 30 min. After dispersing was stopped, the mixture was cooled to room temperature and stored in a vacuum drying oven for 48 h for defoaming to obtain a follow-up sealant.

[0051] Comparative Example 1

[0052] This comparative example uses unmodified SEEPS-OH elastomer particles as a thickener to prepare a follow-up sealant, comprising the following steps:

[0053] Add 50.0g of unmodified SEEPS-OH elastomer particles (weight average molecular weight 20000) to 39.8g of mineral oil, heat to 130°C, stir at constant temperature for 90min, transfer to a high-speed disperser, and disperse at high speed at 5000rpm for 60min. Add 10.0g of plasticizer ethyl rubber, continue to disperse at high speed for 45min, add 0.2g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40min. Stop dispersion and cool to room temperature. Store in a vacuum drying oven for 48h for defoaming to obtain a follow-up sealant.

[0054] Comparative Example 2

[0055] The preparation of the follow-up sealant of this comparative example comprises the following steps:

[0056] (1) Preparation of thickener

[0057] 4000g of mineral oil was added to a reactor, and the temperature was raised to 110°C. 993.39g of SEEPS-OH elastomer particles (weight average molecular weight 20000) were added under stirring to make them uniformly dispersed, and then 10g of KOH powder was added as a catalyst, and the mixture was replaced with dry nitrogen for 3 times. The mixture was dehydrated at 120°C and -0.07MPa, and the temperature was raised to 140°C. 6.61g of ethylene oxide was introduced, and the pressure in the reactor was kept at ≤0.4MPa. When the pressure in the reactor remained unchanged, nitrogen was replaced, and the reaction was completed. 200g of activated carbon was added and stirred for 30min to adsorb potassium hydroxide catalyst, and the activated carbon adsorbed with potassium hydroxide was removed by filtering while hot, and the temperature was lowered to obtain a mixture of base oil and ethoxy-modified SEEPS-OH dispersed in the base oil, which was a thickener. The ethoxy content in the obtained ethoxy-modified SEEPS-OH elastomer was 0.15mol / kg.

[0058] (2) Preparation of follow-up sealant

[0059] Add 50.0 g of the thickener prepared in step (1) to 39.8 g of mineral oil, heat to 130° C., stir at constant temperature for 90 min, transfer to a high-speed disperser, and disperse at high speed at 5000 rpm for 60 min. Add 10.0 g of plasticizer ethyl rubber, continue to disperse at high speed for 45 min, add 0.2 g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40 min. Stop dispersing and cool to room temperature. Store in a vacuum drying oven for 48 h to defoam, and obtain a follow-up sealant.

[0060] Comparative Example 3

[0061] The preparation of the follow-up sealant of this comparative example comprises the following steps:

[0062] (1) Preparation of thickener

[0063] 4000g of mineral oil was added to a reactor, and the temperature was raised to 110°C. 980.18g of SEEPS-OH elastomer particles (weight average molecular weight 20000) were added under stirring to make them uniformly dispersed, and then 10g of KOH powder was added as a catalyst, and the mixture was replaced with dry nitrogen for 3 times. The mixture was dehydrated at 120°C and -0.07MPa, and the temperature was raised to 140°C. 19.82g of ethylene oxide was introduced, and the pressure in the reactor was kept at ≤0.4MPa. When the pressure in the reactor remained unchanged, nitrogen was replaced, and the reaction was completed. 200g of activated carbon was added and stirred for 30min to adsorb potassium hydroxide catalyst, and the activated carbon adsorbed with potassium hydroxide was removed by filtering while hot, and the temperature was lowered to obtain a mixture of base oil and ethoxy-modified SEEPS-OH dispersed in the base oil, which was the thickener; the ethoxy content in the obtained ethoxy-modified SEEPS-OH elastomer was 0.45mol / kg;

[0064] (2) Preparation of follow-up sealant

[0065] Add 50.0 g of the thickener prepared in step (1) to 39.8 g of mineral oil, heat to 130° C., stir at constant temperature for 90 min, transfer to a high-speed disperser, and disperse at high speed at 5000 rpm for 60 min. Add 10.0 g of plasticizer ethyl rubber, continue to disperse at high speed for 45 min, add 0.2 g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40 min. Stop high-speed dispersion, cool to room temperature, and store in a vacuum drying oven for 48 h to defoam, to obtain a follow-up sealant.

[0066] Comparative Example 4

[0067] The preparation of the follow-up sealant of this comparative example comprises the following steps:

[0068] (1) Preparation of thickener

[0069] The same preparation contents of the thickener as in Example 1;

[0070] (2) Preparation of follow-up sealant

[0071] Add 40.0 g of the thickener prepared in step (1) to 49.8 g of mineral oil, heat to 130° C., stir at constant temperature for 90 min, transfer to a high-speed disperser, and disperse at high speed at 5000 rpm for 60 min. Add 10.0 g of plasticizer ethyl rubber, continue to disperse at high speed for 45 min, add 0.2 g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40 min. Stop dispersing and cool to room temperature. Store in a vacuum drying oven for 48 h to defoam, and obtain a follow-up sealant.

[0072] Comparative Example 5

[0073] The preparation of the follow-up sealant of this comparative example comprises the following steps:

[0074] (1) Preparation of thickener

[0075] The same preparation contents of the thickener as in Example 1;

[0076] (2) Preparation of follow-up sealant

[0077] Add 80.0 g of the thickener prepared in step (1) to 9.8 g of mineral oil, heat to 130° C., stir at constant temperature for 90 min, transfer to a high-speed disperser, and disperse at high speed at 5000 rpm for 60 min. Add 10.0 g of plasticizer ethyl rubber, continue to disperse at high speed for 45 min, add 0.2 g of antioxidant butyl hydroxybenzoic acid, and disperse at high speed for another 40 min. Stop high-speed dispersion, cool to room temperature, and store in a vacuum drying oven for 48 h to defoam, to obtain a follow-up sealant.

[0078] The weight of each auxiliary agent in the embodiments and comparative examples is shown in Table 1.

[0079] Table 1 Ethoxy content in ethoxy-modified SEEPS-OH elastomer prepared in examples and comparative examples and mass of each auxiliary agent in preparing follow-up sealant

[0080]

[0081] The viscosities of the follow-up sealants prepared in the examples and comparative examples were tested at a rotation speed of 6 rpm using a No. 4 rotor of a rotational viscometer. The data are shown in Table 2.

[0082] Table 2 Viscosity data of follow-up sealant 6rpm obtained in Examples and Comparative Examples

[0083]

[0084] The viscosity of the follower sealant of the embodiment at a rotation speed of 6 rpm is in the range of 30,000 to 50,000 cp. The viscosity of the follower sealants of Comparative Examples 1, 2 and 3 at a rotation speed of 6 rpm is similar to that of Example 1. The thickening effects of the modified SEEPS-OH elastomers and the unmodified SEEPS-OH with different ethoxy contents are basically similar. The ethoxy modification only occurs on the terminal hydroxyl groups of the SEEPS-OH elastomer, which is only a very small part relative to the SEEPS-OH main chain and does not affect its thickening performance. Comparative Example 4 uses the same thickener as Example 1, but the added mass accounts for 40.0% of the whole. The viscosity of the prepared follower sealant at a rotation speed of 6 rpm is lower than 30,000 cp. Comparative Example 5 uses the same thickener as Example 1, but the added mass accounts for 80.0% of the whole. The viscosity of the prepared follower sealant at a rotation speed of 6 rpm is higher than 50,000 cp.

[0085] Commercially available neutral ink, pen tips, connections, oil pipes (inner diameter 2.75 mm), sheaths, and the follow-up sealants prepared in the embodiments and comparative examples were used to prepare the refills of neutral ink ballpoint pens (the follow-up sealant was poured into the tail end of the oil pipe). After centrifugation, the refills that opened normally were selected for the following application performance test and evaluated according to the standards. The evaluation results are shown in Table 3.

[0086] 1. Follow-up test

[0087] Take 5 refills and scribble on the scribing instrument at a scribing speed of 4.5m / min. After 400m scribing, measure the residual height of the follow-up sealant, and record the ratio of the residual height to the initial height as the residual rate. Take the average of the residual rates of the 5 refills. The higher the value, the better the follow-up performance.

[0088] When the ink consumption of the refill is the same, the smaller the inner diameter of the oil tube, the faster the ink will drop, and the higher the follow-up requirements of the follow-up sealant. The refill of the commercially available neutral ink ballpoint pen usually has a minimum inner diameter of 2.75mm, and the average residual rate is usually less than 50%.

[0089] 2. Drop resistance test

[0090] Drop the pen core from a height of 1m through a vertical pipe onto a 2cm thick fir board 10 times, observe the state of the follow-up sealant and evaluate it according to the following standards:

[0091] The follow-up sealant has no deformation: A;

[0092] The follow-up sealant is deformed and a small amount of ink penetrates into the sealant: B;

[0093] The follow-up sealant overflows from the pen core, and a large amount of ink seeps into the follow-up sealant: C.

[0094] 3. Ink leakage test when the pen core is placed upside down

[0095] In an environment of 50±1℃, keep the pen tip (with a sheath) upright for 30 days, and observe whether there is any phenomenon of the follower sealant leaking into the ink. The evaluation criteria are as follows:

[0096] No ink leakage: A;

[0097] Partial ink leakage: B;

[0098] Most ink spills: C.

[0099] 4. Drip performance test

[0100] In an environment of 50±1℃, keep the pen tip (with sheath) upright for 30 days, observe the degree of dripping of the follow-up sealant on the inner wall of the oil pipe and evaluate it according to the following standards:

[0101] No drip: A;

[0102] Some of the follow-up sealant drips to the tail of the oil pipe: B;

[0103] There is considerable dripping of the follower sealant and some of it flows out of the pen barrel: C.

[0104] Table 3 Application performance test results of the refills of neutral ink ballpoint pens made of follow-up sealants in the embodiments and comparative examples

[0105]

[0106] The follow-up performance of the core of the neutral ink ballpoint pen made of the follow-up sealant in the embodiment is above 75%, that is, after the ink in the core is written, there is still enough follow-up sealant to ensure the anti-fall and anti-backflow of the core, and the other three tests are all A.

[0107] Comparative Example 1: The follow-up sealant prepared by using unmodified SEEPS-OH elastomer as a thickener has poor affinity with the inner wall of the oil pipe of the pen core and the ink, and has the worst follow-up performance. Comparative Example 2: The ethoxy content of the modified SEEPS-OH elastomer in the follow-up sealant is 0.15 mol / kg, and the affinity of the thickener with the inner wall of the oil pipe of the pen core and the ink has not changed significantly. The follow-up sealant prepared by using this thickener fails to achieve good follow-up performance. Comparative Example 3: The ethoxy content of the modified SEEPS-OH elastomer in the follow-up sealant is 0.45 mol / kg, and the hydrophilicity of the thickener is significantly improved. The prepared follow-up sealant is applied to the core of a neutral ink ballpoint pen and has good follow-up performance. However, the anti-drop and dripping performances are average, and the ink leakage performance when the pen core is turned upside down is poor. Comparative Example 4: A low viscosity solution is used, and the follow-up performance is very good, but the anti-drop and dripping performances are very poor. Comparative Example 5 adopts a high viscosity solution, and has good anti-fall performance, but poor follow-up performance. None of the comparative examples achieves good comprehensive performance.

[0108] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary, and various other substitutions, changes and improvements may be made within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but only to the claims.

Claims

1. A neutral ink ballpoint pen follower sealant, comprising, by weight: 19 to 40 parts of base oil, 5 to 10 parts of plasticizer, 0.2 to 0.5 parts of antioxidant and 50 to 75 parts of thickener; The thickener is prepared by ethoxy-modifying SEEPS-OH elastomer in the base oil; The structural formula of SEEPS-OH elastomer is as follows: The weight average molecular weight of the SEEPS-OH elastomer is 20000-40000, wherein i, j, k, m and n are all integers greater than 0.

2. The follower sealant according to claim 1, characterized in that: The structural formula of the ethoxy-modified SEEPS-OH elastomer is as follows: Here, p is an integer greater than 0.

3. The follower sealant according to claim 1 or 2, characterized in that: The content of ethoxy groups in the ethoxy-modified SEEPS-OH elastomer is 0.2-0.4 mol / kg.

4. The follower sealant according to claim 1, characterized in that: The base oil is one of mineral oil, dimethyl silicone oil and polyalphaolefin (PAO).

5. The follower sealant according to claim 1, characterized in that: The plasticizer is one of ethyl rubber, propyl rubber, butyl rubber, phenyl silicone rubber and styrene-butadiene rubber.

6. The follower sealant according to claim 1, characterized in that: The antioxidant is one of butylated hydroxybenzoic acid and tri-tert-butylated hydroxyanisole.

7. The follower sealant according to claim 1, characterized in that: The viscosity of the follow-up sealant is 30000-50000 cp at a rotation speed of 6 rpm using a No. 4 rotor of a rotational viscometer.

8. The method for preparing the follower sealant according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Preparation of thickener The SEEPS-OH elastomer particles are dispersed in a base oil at 110-120° C., 0.2% of the total mass of KOH powder is added as a catalyst, replaced with dry nitrogen three times, dehydrated at 110-120° C. and -0.07--0.09 MPa for 20-30 min, heated to 140-150° C., ethylene oxide is introduced, and the pressure in the reactor is maintained at ≤0.4 MPa. When the pressure in the reactor remains unchanged, nitrogen is introduced, and the reaction is completed. Activated carbon is added and stirred for 30 min to adsorb the potassium hydroxide catalyst, and the activated carbon adsorbed with potassium hydroxide is removed by hot filtration, and the temperature is lowered to obtain a mixture of the base oil and the ethoxy-modified SEEPS-OH dispersed in the base oil, which is a thickener; (2) Preparation of follow-up sealant Add thickener to base oil, raise the temperature to 130-170°C, stir at constant temperature for 30-90 minutes after the temperature reaches the target value, transfer to high-speed disperser, disperse at 5000-8000rpm for 30-60 minutes, add plasticizer, continue high-speed dispersion for 30-60 minutes, add antioxidant, and disperse at high speed for another 20-40 minutes. Stop high-speed dispersion and cool to room temperature. Store in vacuum drying oven for 48 hours for defoaming to obtain follow-up sealant.

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