JPH0354066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink-impregnated body containing and retaining ink in a microporous substrate such as an ink pad or an ink roll, and a method for manufacturing the same.

Conventionally, ink-impregnated bodies of this type, such as ink pads and ink rolls, use vulcanized hydrophobic soft thermoplastic plastics or nearly hydrophobic cross-linked rubber as the main material, and a continuous process to impregnate the ink into the vulcanized material. It has a microporous structure (see JP-A-53-61654 for a product using cross-linked rubber).

However, when hydrophobic soft thermoplastics are used, the plasticizers and softening agents contained in them are eluted into the ink that is retained, causing the hardness of the main material to change over time. A drawback is that it is extremely difficult to adjust the hardness of the ink-impregnated body to an appropriate level. In addition, for hydrophobic ink, the balance between the ink retention function of the hydrophobic part and the ink release function of the hydrophilic part is set appropriately so that the retained ink oozes out in appropriate amounts over a long period of time. However, it is preferable to
It is difficult to mix and use hydrophilic polymers with hydrophobic polymers, and it is difficult to control the ratio of hydrophilic polymers to hydrophobic polymers.

On the other hand, if the main material is a vulcanized crosslinked rubber, continuous molding is difficult because vulcanization is required.

In addition, when solvents, salt, etc. are used as porosity-forming agents, the heat generated when they are mixed causes vulcanization to proceed, making molding difficult. Therefore, it is difficult to form continuous micropores with a set size. Furthermore, since the hardness changes with subtle changes in heating temperature, it is difficult to manufacture products with a predetermined hardness.

As described above, the properties of conventional ink-impregnated bodies of this kind are easily affected by the pressure and temperature conditions during manufacturing, and if these conditions deteriorate even slightly, bleeding, fading, or ink droplets may occur on the printed surface. Another drawback is that it continues to retain a large amount of ink even after its life has ended.

JP-A-55-115433 describes continuous molding of an ink-impregnated base material by injection molding or the like using thermoplastic elastomer or crosslinked rubber as the main material.

However, simply using a thermoplastic elastomer as an ink-impregnated base material makes it difficult to adjust the hardness of the ink-impregnated base material, and it is also difficult to balance the ink retention function and ink release function, making it difficult to adjust the amount of ink seepage. , impregnation ink cannot be used effectively.

As a result of extensive research by the present inventors to eliminate such drawbacks, we found that when using a specific thermoplastic block elastomer as the main material of the ink-impregnated body,
It has been discovered that the hardness and the ratio of hydrophobicity to hydrophilicity can be properly controlled, and that an ink-impregnated body can be easily produced without the need for vulcanization or without using plasticizers or softeners, and the present invention has been developed. It was completed.

That is, the present invention provides: (1) a skeleton material of at least one thermoplastic block elastomer selected from the group consisting of a polyamide block elastomer, a polyimide block elastomer, and a polyester block elastomer; An ink-impregnated body formed by impregnating a hydrophobic liquid ink into a continuous microporous body having large pores and porosity; (2) a group consisting of polyamide block elastomers, polyimide block elastomers, and polyester block elastomers; A powder that forms pores in at least one type of thermoplastic block elastomer selected from the group consisting of pores having a size necessary as an ink-impregnated base material in a continuous fine porous body using the elastomer as a skeleton material, the powder forming pores having a size necessary as an ink-impregnated base material. A state in which a mixture obtained by dispersing and mixing a powder soluble in a solvent that does not dissolve the block elastomer in an amount that provides the necessary porosity as an ink-impregnated base material is heated to a temperature higher than the softening point of the thermoplastic block elastomer to plasticize it. molded into a predetermined shape, and then cooled to below the softening point of the thermoplastic block elastomer to solidify it,
The powder is dissolved and removed from the solidified molded product using a solvent inert to the thermoplastic block elastomer to form a microporous base material of a predetermined shape, and the microporous base material is impregnated with a hydrophobic liquid ink. and (3) adding the elastomer to at least one thermoplastic block elastomer selected from the group consisting of a polyamide block elastomer, a polyimide block elastomer, and a polyester block elastomer. A mixture is prepared by dispersing and mixing a foaming agent that forms pores with a size necessary for an ink-impregnated base material in a continuous fine porous body having a skeleton material in an amount that provides the necessary porosity as an ink-impregnated base material. The thermoplastic block elastomer is heated above the softening point and above the foaming temperature of the blowing agent, and then foamed and formed into a predetermined shape, cooled and solidified to form a microporous base material with a predetermined shape. The present invention provides a method for producing an ink-impregnated body in which the microporous substrate is impregnated with a hydrophobic liquid ink.

Thermoplastic block elastomers are new molding materials developed to improve the impact resistance of molded products against external forces, and are block copolymerized with a soft component that provides flexibility. Therefore, by appropriately selecting the composition, the hardness of the molded product can be adjusted over a wide range, and except in special cases, molding can be carried out without using plasticizers or softeners or without vulcanization. It is possible.

Among thermoplastic block elastomers having such properties, the present inventors have noticed that the specific thermoplastic block elastomer is particularly useful as a skeleton material for ink-impregnated base materials that require appropriate elasticity, and further As a result of repeated research, it was discovered for the first time that the ratio of hydrophilicity and hydrophobicity can be further adjusted appropriately in the above-mentioned specific thermoplastic block elastomer, and the ink-impregnated body of the present invention, which can also control the ink-retaining ability of the ink-impregnated body, was completed. did.

In the ink-impregnated body of the present invention in which the specific thermoplastic block elastomer is used as the skeleton material of the ink-impregnated base material, the ratio of hydrophilicity and hydrophobicity can be adjusted appropriately, so that ink fading and There are no problems such as dripping or a large amount of ink remaining even after the service life has expired. Furthermore, there is no risk of changes in hardness over time due to elution of additives, and the quality of the ink contained therein will not change. Further, since the hardness can be adjusted easily and with high precision, an ink-impregnated body having optimal mechanical properties can be easily manufactured.

The thermoplastic block elastomers used in the present invention include polyamide block elastomers such as block copolymers of polyamide and polyether or polyester, polyimide elastomers such as block copolymers of polyimide and polyether or polyester, and polyether ester blocks. Examples include polyester elastomers such as copolymers (for example, block copolymers of polybutylene terephthalate (obtained from 1,4-butanediol and dimethyl terephthalate) and polytetramethylene ether glycol, etc.).

Especially polyether amide block copolymer,
Polyesteramide block copolymers and polyetherimide block copolymers are preferred.

All of these thermoplastic block elastomers have the necessary strength as an ink-impregnated base material at room temperature, and are suitably used as the skeleton material of the ink-impregnated base material in the present invention. It is important to select a material that has a suitable ratio of hydrophilicity to hydrophobicity, dimensional stability, hardness, etc.

The thermoplastic block elastomer can be freely adjusted from hydrophobic to highly hydrophilic, but in the ink-impregnated body of the present invention, if the hydrophilicity becomes too high, the ink will easily drip off, and if the ink is not hydrophilic. If it becomes too low, a large amount of ink will remain even after the life of the ink-impregnated body is over, so
It is preferable that the water absorption rate is adjusted to 1 to 50%, particularly 2 to 20%.

Specific examples of the polyamide block elastomer include Nyrim 20 (manufactured by Monsanto).

Specific examples of the polyimide block elastomer include Ultem 1000, Ultem
2100, Ultem 2200, Ultem 2300 (general
(manufactured by Electric Co., Ltd.).

Specific examples of the polyester block elastomer include Hytrel 5556, Hytrel 6346, Hytrel 4056 (all trade names of DuPont), Belprene P40H, Belprene P70B,
Examples include Belprene P150M and Belprene P150B (both trade names of Toyobo Co., Ltd.).

The ink-impregnated body of the present invention is a powder that allows the thermoplastic block elastomer to form pores having a size necessary as an ink-impregnated base material in a continuous microporous body using the elastomer as a skeleton material, and A powder soluble in a solvent that does not dissolve the thermoplastic block elastomer is dispersed and mixed in an amount that provides the necessary porosity as an ink-impregnated base material, and the dispersed mixture is heated to a temperature higher than the softening point of the thermoplastic block elastomer. The powder is heated, plasticized and molded into a predetermined shape, and then cooled to below the softening point of the thermoplastic block elastomer to solidify it. It is obtained by dissolving and removing with a solvent to form a microporous base material of a predetermined shape, and impregnating the microporous base material with a hydrophobic liquid ink.

In the above, the thermoplastic block elastomer and the powder are mixed in advance and then heated and fluidized, but the thermoplastic block elastomer may be plasticized by heating above its softening point in advance, and the powder may be mixed therein.

Examples of the powder include salt, starch,
Examples include powders such as water-soluble gypsum, acicular crystal fibers, sodium bicarbonate, and calcium sulfite.
Continuous micropores can be formed by dissolving these powders with a solvent after molding.

The ink-impregnated body of the present invention can also be produced by the following method. That is, a foaming agent is added to the thermoplastic block elastomer to form pores having a size necessary as an ink-impregnated base material in a continuous microporous body using the elastomer as a skeleton material. the dispersion-mixed mixture is heated to a temperature higher than the softening point of the thermoplastic elastomer and higher than the foaming temperature of the foaming agent, and then foamed to form a predetermined shape; It is obtained by cooling and solidifying to form a microporous base material of a predetermined shape, and then impregnating the microporous base material with a hydrophobic liquid ink.

In the above method, the thermoplastic block elastomer and the blowing agent are mixed in advance and then heated and fluidized. A blowing agent may be mixed with the foaming agent.

As a blowing agent, for example, sodium bicarbonate,
Examples include carbondiamide, dinitropentamethylenetetramine, p,p'-oxybisbenzenesulfonyl hydrazide, and the like.

In both of the above methods, the mechanical properties can be improved by adding reinforcing materials such as carbon black, graphite, silica, potassium titanate, and carbon fabric.

The thermoplastic block elastomer used is preferably in a solid form such as powder, pellet, or granule at room temperature.

Heating to fluidize the thermoplastic block elastomer is carried out to ensure uniform mixing with the powder or foaming agent and to facilitate molding. Therefore, when using a blowing agent, the temperature should not be raised above its foaming temperature. Usually about
It may be carried out at 150 to 280°C.

When the method of the present invention is used, there is no need for vulcanization and the molding process can be carried out continuously, so productivity can be greatly improved.
As the molding method, continuous molding methods such as extrusion molding, injection molding, rolling molding, and rotational molding can be adopted.

The present invention will now be described based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 A molded article for an ink roll was injection molded using a polyetheramide block copolymer as a thermoplastic block elastomer.

The physical properties of the polyetheramide block copolymer used are as follows.

Melting point: 168℃ Shore hardness: 55D Water absorption (immersed in water for 24 hours): 1.2% Polyetheramide block copolymer 100
Part (by weight, the same applies hereinafter), SRF Carbon Black
20 parts and 650 parts of common salt (100 mesh passes) were heated and fluidized at 150° C. using two rolls and mixed uniformly. This material was injected into an injection molding machine to injection mold a molded article for an ink roll (diameter 35 mm, length 50 mm).

The obtained molded body was placed in a water bath to dissolve out the salt in the molded body, thereby obtaining an ink-impregnated base material having a continuous micropore structure. The emptiness rate for this item was approximately 70%. Further, the surface hardness of this ink-impregnated base material (measured with a rubber hardness meter Acquer C type) was 35 degrees, and the water absorption rate was 1.2%.

A hydrophobic ink (an ink consisting of 15 parts of carbon black, 5 parts of nigrosine base, 1 part of methyl violet, 45 parts of mineral oil, and 34 parts of isostearic acid) is added to the ink-impregnated base material to form an ink roll, and this is made into a mini roll. When it was attached to a printer and printed, it was able to print 500,000 times continuously without any bleeding or fading on the printing surface, and without any ink dripping. When we investigated the ink content of the ink roll that had reached the end of its lifespan, we found that 18% of the original ink remained, indicating that the ink was being used extremely efficiently.

Example 2 An ink-impregnated base material was produced in the same manner as in Example 1 except that raw materials having the following composition were used.

Polyester amide block copolymer 100 parts SRF carbon black 30 parts Common salt (300 mesh pass) 750 parts The physical properties of the polyester amide block copolymer used are as follows.

Melting point: 176°C Shore hardness: 55D Water absorption (immersed in water for 24 hours): 4% The porosity of the obtained ink-impregnated base material was about 71%. In addition, the surface hardness of this ink-impregnated base material (measured with a rubber hardness meter Asker C type) is 40 degrees,
The water absorption rate was 4.0%.

A hydrophobic ink (an ink consisting of 14 parts of carbon black, 6 parts of nigrosine base, 1 part of methyl violet, 47 parts of mineral oil, and 32 parts of isostearic acid) is added to the ink-impregnated base material to form an ink roll. When it was attached to a label printer (manufactured by Yukichoki Co., Ltd.) and used for printing, it was possible to print 600,000 times continuously without any bleeding or fading on the printing surface and without any ink droplets. When we investigated the ink content of the ink roll that had reached the end of its lifespan, we found that only 16% of the original ink remained.
Ink was used extremely efficiently.

Example 3 An ink-impregnated base material was prepared in the same manner as in Example 1, except that the following polyetheramide block copolymer was used as the thermoplastic block elastomer.

The physical properties of the polyetheramide block copolymer used are as follows.

Melting point: 190°C Shore hardness: 40D Water absorption (immersed in water for 24 hours): 18% The porosity of the obtained ink-impregnated base material was about 75%. In addition, the surface hardness of this ink-impregnated base material (measured with a rubber hardness meter Asker C type) is 47 degrees.
The water absorption rate was 18%.

When the ink-impregnated base material was impregnated with the hydrophobic ink used in Example 1 to form an ink roll, and the ink roll was attached to a mini printer and used for printing, no bleeding or fading occurred on the printed surface, and the ink was It was possible to print 550,000 times continuously without any dropouts. When we investigated the ink content of the ink roll that had reached the end of its lifespan, we found that 21% of the original ink roll remained.
Ink was used extremely efficiently.

Example 4 An ink-impregnated base material was prepared in the same manner as in Example 1 except that the following polyetheramide block copolymer was used as the thermoplastic block elastomer.

The physical properties of the polyetheramide block copolymer used are as follows.

Melting point: 165°C Shore hardness: 35D Water absorption (immersed in water for 24 hours): 48% The porosity of the obtained ink-impregnated base material was about 70%. In addition, the surface hardness of this ink-impregnated base material (measured with a rubber hardness meter Asker C type) is 38 degrees.
The water absorption rate was 48%.

When the ink-impregnated base material was impregnated with the hydrophobic ink used in Example 1 to form an ink roll, and the ink roll was attached to a mini printer and used for printing, no bleeding or fading occurred on the printed surface, and the ink was It was possible to print 450,000 times continuously without any dropouts. When we investigated the ink content of the ink roll that had reached the end of its lifespan, we found that only 22% of the original ink remained.
Ink was used extremely efficiently.

Example 5 A molded article for an ink pad was injection molded using a polyetheramide block copolymer as a thermoplastic block elastomer.

The physical properties of the polyetheramide copolymer used are as follows.

Melting point: 195℃ Shore hardness: 63D Water absorption rate (immersed in water for 24 hours): 10% As a blowing agent, 20 parts of carbon whisker single crystal fiber was immersed in a 0.5% toluene solution of carbondiamide, and then the toluene was evaporated. A carbon whisker single crystal fiber with carbon diamide attached to its surface was used.

100 parts of polyether amide block copolymer and the above foaming agent were mixed at 150°C using two rolls, molded using an injection molding machine, and then heated in a mold to foam, resulting in a continuous microporous structure. An ink pad base material (25 mm x 60 mm x 6 mm) having the following was produced. The emptiness rate for this item was approximately 72%. In addition, the surface hardness of this ink pad base material (measured with a rubber hardness meter Asker C type) is 38 degrees, and the water absorption rate is
It was 10%.

The hydrophobic ink used in Example 1 is contained in the ink pad base material to form an ink pad,
When I attached this to a mini printer and used it for printing, there was no bleeding or fading on the printed surface.
It was possible to print 300,000 times continuously without any ink dripping. When we investigated the ink content of the ink pads that had reached the end of their lifespan, we found that only 22% of the original ink pad remained, indicating that the ink was being used extremely efficiently.

Example 6 An ink pad was prepared in the same manner as in Example 5 except that a polyetherimide block copolymer was used as the thermoplastic block elastomer.

The physical properties of the polyetherimide block copolymer used are as follows.

Melting point: 210℃ Shore hardness: 57D Water absorption rate (immersed in water for 24 hours): 10% The porosity of the obtained ink pad base material is approximately 70%
It was hot. The surface hardness of this ink pad base material (measured with a rubber hardness meter Asker C type) was 38 degrees, and the water absorption rate was 10%.

This ink pad base material is made into an ink pad by containing the hydrophobic ink used in Example 1,
When I attached this to a mini printer and used it for printing, there was no bleeding or fading on the printed surface.
It was possible to print 600,000 times continuously without any ink dripping. When we investigated the ink content of the ink pads that had reached the end of their lifespan, we found that only 16% of the original ink remained, indicating that the ink was being used extremely efficiently.

The water absorption rate can be freely adjusted by blending block copolymers having different water absorption rates as long as they are composed of the same copolymer components.

Comparative Example 1 A pellet-like resin of saponified ethylene-vinyl acetate copolymer (melting point 178°C) with an ethylene content of 32 mol% and a vinyl acetate component saponification degree of 98.5 mol% was crushed with a pulverizer to a pellet of 75 to 197μ. The particles were sieved. The obtained particles were filled into a pipe-shaped mold with an outer diameter of 40 mm and an inner diameter of 20 mm that had been preheated to 120°C, and then the temperature was raised under pressure and sintered by keeping the temperature at which only the surface of the particles melted. After cooling, the ink-impregnated substrate (empty) in the form of hydrophobic thermoplastic
The hydrophobic ink used in Example 1 was occluded therein to obtain an ink roll. This ink-impregnated base material had a surface hardness (measured using Asker C type rubber hardness) of 40 degrees and a melting point of 178 degrees Celsius.

When the ink roll was subjected to printing in the same manner as in Example 1, the surface hardness was 20 after 300,000 printings.
It gradually changed and became softer, and the printed image became larger. When we investigated the ink content at the time the staining occurred, we found that as much as 60% of the original ink remained.

Comparative Example 2 Sulfur in weight ratio to 100 parts of synthetic rubber (NBR)
2.5 parts, zinc white 5 parts, vulcanization accelerator 3 parts, liquid rubber (low polymerization NBR) 10 parts, vaseline 10 parts, DOP 10 parts,
50 parts of carbon black, 2 parts of anti-aging agent, and 800 parts of common salt (80 to 100 mesh passes) were added and masticated to prepare a mixture. This is filled into a roll molding mold, pressurized between hot platens, heated and cured at 150℃ for 15 minutes, then released from the mold, thoroughly washed with water to completely dissolve the salt, dehydrated and dried, and occluded the ink. A vulcanized rubber ink roll was produced. The void ratio of the obtained ink roll was about 70%, but the size of the micropores varied from 70 to 150 μm and was non-uniform.

In addition, the surface hardness of the ink-impregnated base material before ink impregnation (measured with a rubber hardness meter Asker C type) is 35 degrees,
The density was 0.13 g/cm ³ .

When the ink roll was subjected to printing in the same manner as in Example 1, the surface hardness was 20 after 400,000 printings.
It gradually changed and became softer, and the print became larger. When the ink content of the ink roll was examined at the time the fading occurred, 55% of the original ink remained.

Claims (1)

[Scope of Claims] 1. At least one thermoplastic block elastomer selected from the group consisting of a polyamide block elastomer, a polyimide block elastomer, and a polyester block elastomer as a skeleton material, and having a size necessary as an ink-containing base material. An ink-impregnated body comprising a continuous fine porous body having pores and voids impregnated with a hydrophobic liquid ink. 2. The thermoplastic block elastomer according to claim 1, wherein the thermoplastic block elastomer comprises at least one selected from the group consisting of polyetheramide block copolymers, polyesteramide block copolymers, and polyetherimide block copolymers. Ink-impregnated body. 3. The ink-impregnated body according to claim 1 or 2, wherein the thermoplastic block elastomer has a water absorption rate of 1 to 50%. 4 At least one type of thermoplastic block elastomer selected from the group consisting of polyamide block elastomer, polyimide block elastomer, and polyester block elastomer, and a continuous microporous body having the elastomer as a skeleton material as an ink-impregnated base material. A mixture obtained by dispersing and mixing a powder that forms pores having a required size and that is soluble in a solvent that does not dissolve the thermoplastic block elastomer in an amount that provides the necessary porosity as an ink-impregnated base material. The thermoplastic block elastomer is heated above the softening point of the thermoplastic block elastomer to be plasticized and molded into a predetermined shape, and then cooled below the softening point of the thermoplastic block elastomer to solidify it, and the powder is extracted from the solidified molded product. Ink impregnation, characterized in that the thermoplastic block elastomer is dissolved and removed using an inert solvent to form a microporous base material of a predetermined shape, and the microporous base material is impregnated with a hydrophobic liquid ink. How the body is manufactured. 5. The production according to claim 4, which comprises dispersing and mixing the powder into the thermoplastic block elastomer, and then heating the dispersion-mixed mixture above the softening point of the thermoplastic block elastomer to plasticize and mold it. Law. 6 At least one thermoplastic block elastomer selected from the group consisting of polyamide block elastomer, polyimide block elastomer, and polyester block elastomer, and a continuous microporous body having the elastomer as a skeleton material as an ink-impregnated base material. A mixture obtained by dispersing and mixing a blowing agent that forms pores having a required size in an amount that provides the necessary porosity as an ink-impregnated base material is heated to a temperature equal to or higher than the softening point of the thermoplastic block elastomer, and the blowing agent is foamed. Foam it into a predetermined shape by heating it above temperature, cool and solidify it to form a microporous base material with a predetermined shape,
A method for producing an ink-impregnated body, which comprises then impregnating the microporous substrate with a hydrophobic liquid ink. 7 The blowing agent is dispersed and mixed in the thermoplastic block elastomer, and then the dispersed mixture is heated to a temperature higher than the softening point of the thermoplastic block elastomer and lower than the foaming temperature of the blowing agent to plasticize it, and then foamed. , the manufacturing method according to claim 6, which involves molding.