JP3047963B2 - Elastic roller for offset printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic roller for offset printing, and more particularly, to an offset roller having low hardness, aging with respect to printing ink and a cleaning agent, compression set, low heat generation and the like. Offset printing having a surface coating layer formed from a recyclable thermoplastic dynamic vulcanizing elastic composition, which has the necessary performance as an elastic roller and does not require a long vulcanization step during molding. For example, the present invention relates to an elastic roller for ink, for example, an ink feeding roller, an ink kneading roller, an ink forming roller, a water forming roller, and a water base roller in an offset printing press.

[0002] An ink feeding roller is a roller that oscillates between an ink fountain roller and a kneading roller to supply ink to a group of ink rollers. The ink kneading roller is a roller that applies a shearing force to the ink supplied via the call-up roller by a plurality of rollers to give the ink fluidity and a uniform film thickness. The ink application roller is a roller that supplies the ink sufficiently kneaded and uniformized by the kneading roller to the plate surface. The fountain roller is a roller for uniformly supplying the dampening solution placed in the watercraft to the spreading roller. The dampening roller is a roller that supplies dampening water supplied from the fountain roller to the plate surface.

[0003]

2. Description of the Related Art The surface coating layer of an elastic roller for offset printing is mainly made of acrylonitrile-butadiene rubber (NBR) having excellent oil resistance and rubber elasticity. However, since NBR is a vulcanized rubber, Its production has the disadvantage that a long vulcanization step is required and the vulcanized rubber cannot be recycled.

On the other hand, in recent years, various thermoplastic elastomers having rubber properties for applications such as hoses, tubes, bumpers, and rollers for OA equipment have been developed.
(1) JP-A-2-215851 discloses a dynamic vulcanization composition comprising polyvinyl chloride (PVC) / NBR / plasticizer / crosslinking agent, and (2) JP-A-8-143199.
In the publication, thermoplastic polyurethane (TPU) / NBR /
A dynamic vulcanizing composition comprising a sulfur-based crosslinking agent is disclosed,
(3) JP-A-5-78550 discloses polyamide resin / maleic anhydride-modified SEBS / NBR or acrylic rubber (ACM) or epichlorohydrin rubber (CH).
A dynamic vulcanization composition comprising R) is disclosed.

[0005] However, the composition disclosed in the above-mentioned patent publication is not designed for an elastic roller for offset printing, so that the composition changes over time, the compression set, and the dynamic heat generation with respect to printing ink and a cleaning agent. It is not a thermoplastic elastomer composition having a good balance between the performance required for an elastic roller for offset printing such as the properties and the moldability. In the compositions of (1) and (3), a large amount of a low-molecular plasticizer is required to obtain a hardness that can be used for a printing roller, and the time-dependent change with respect to a printing ink and a cleaning agent cannot be satisfied. With the composition (2), it is difficult to balance rubber performance and processability, and it is difficult to apply the composition to an elastic roller for offset printing which requires formation of a large rubber thickness.

[0006]

SUMMARY OF THE INVENTION The present invention provides low-hardness properties required for an elastic roller for offset printing, such as aging with respect to printing inks and cleaning agents, compression set, and low heat generation. Equipped with a surface coating layer formed from a recyclable thermoplastic dynamic vulcanized elastic composition that is preferable for offset printing without requiring a long vulcanization step during molding, and has an elasticity for offset printing. A body roller is provided.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a core and a surface coating layer formed thereon, and the surface coating layer is made of acrylonitrile-butadiene rubber. (NBR), vinyl chloride polymer (PV
C-based polymer), thermoplastic polyurethane (TPU), and a plasticizer are formed from a thermoplastic dynamic vulcanized elastic composition obtained by heating and kneading in the presence of a vulcanizing agent and a vulcanization accelerator. An elastic roller for offset printing is provided. Preferably, the thermoplastic dynamic vulcanized elastic composition has a JIS-A hardness of 20 to 40.

According to the present invention, NBR serving as a rubber phase, PVC polymer and TPU serving as a resin phase are converted into a vulcanizing agent,
When heated and mixed with a vulcanization accelerator and a plasticizer, the NBR component is selectively vulcanized and uniformly dispersed in the resin phase, so it has low hardness and excellent rubber elasticity and oil resistance, and is recyclable. A thermoplastic dynamically vulcanized elastic composition can be obtained, and an elastic roller for offset printing can be obtained by forming the composition as a surface coating layer on a core.

The composition used in the present invention comprises, as a resin phase,
Ultra-low hardness TPU with relatively good compatibility with PVC polymer
Is blended, so that the oil resistance and processability of the PVC polymer are not impaired, and the rubber hardness of the composition including the rubber phase NBR, a vulcanizing agent and a vulcanization accelerator and the resin phase, The target rubber hardness can be achieved with a low plasticizer addition amount.

According to the present invention, NBR, a vulcanizing agent and a vulcanization accelerator, which are used as a rubber phase, are mixed with a PVC polymer and a TPU.
Since the rubber phase can be selectively vulcanized by heating and kneading in the resin phase, it is possible to obtain necessary and sufficient elasticity as an elastic roller for offset printing, and to secure good extrusion workability. .

As the NBR used in the present invention, any commercially available NBR can be used. Preferably, the amount of acrylonitrile contained in the molecule is 18-5.
0% by weight is used alone or in combination of two or more. If necessary, partially cross-linked NBR or NBI
R can be used as a blend.

As the PVC polymer contained in the composition used in the present invention, vinyl chloride homopolymer, vinyl chloride homopolymer, Ethylene-vinyl chloride copolymer and vinyl acetate-vinyl chloride copolymer can be used, and these can be used alone or in combination of two or more.

The TPU used in the present invention is produced from a polyol compound and an isocyanate compound, and is used for the purpose of lowering the hardness of a PVC polymer. Therefore, an ultra-low hardness TPU is preferable. The term “ultra-low hardness TPU” as used herein means a rubber having a hardness of 5 degrees or less as measured by a C-type hardness meter and having a solid or viscous liquid property at room temperature.

As the polyol compound, an organic compound having two or more hydroxyl groups is used, and examples thereof include polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, and copolymers thereof. These polyol compounds can be used alone or in combination of two or more.

As the isocyanate compound, general compounds such as tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate and hexamethylene diisocyanate which are bifunctional isocyanates can be used.

The vulcanizing agent contained in the composition used in the present invention may be a usual vulcanizing agent for NBR, for example, sulfur or an organic peroxide. Is preferably sulfur. The amount of vulcanizing agent is N
It may be an amount usually used for vulcanizing BR, and is generally used in an amount of 0.1 to 10 parts by weight, preferably 0.25 to 5 parts by weight, per 100 parts by weight of NBR.

The vulcanization accelerator contained in the composition used in the present invention may be a conventional vulcanization accelerator, for example, thiazole type, sulfenamide type, thiuram type, dithiocarbamate type,
It can be selected from xanthate-based vulcanization accelerators, and these can be used alone or in combination of two or more. In order to obtain a vulcanized reaction product in a relatively short time, thiuram-based, dithiocarbamate-based and xanthate-based superpromoter-based ones are preferred. When a vulcanization accelerator is used, its amount may be a usual amount, and is generally 0.1 to 10 parts by weight, preferably 0.25 to 5 parts by weight, per 100 parts by weight of NBR.
Used in an amount of 5 parts by weight.

The plasticizer used in the present invention may be NBR or PVC.
Any of those generally used for a polymer may be used. Examples thereof include a phthalate ester type, an alkylbenzyl phthalate type, an adipate type, a trimellitate type, an adipic acid type polyester, and a phthalic acid type polyester. More than one species can be used in combination.

NBR as a rubber phase and PVC as a resin phase
Weight ratio between rubber-based polymer and TPU (rubber phase: resin phase)
Is usually 30:70 to 75:25, preferably 40: 6
The range is 0 to 75:25. 30: 7 rubber phase ratio
If it is less than 0, the rubber elasticity of the roller for offset printing becomes insufficient. On the other hand, if it exceeds 75:25, the rubber phase uniform dispersibility at the time of dynamic vulcanization is poor, the extrusion rubber roller moldability is poor, and the thermoplastic elasticity is poor. It is also difficult to put together as a body composition.

The weight ratio of the PVC polymer to TPU (PVC polymer: TPU) contained in the resin phase of the composition used in the present invention is usually 30:70 to 90:10, preferably 40:60 to 70:30. In the range. When the ratio of the PVC-based polymer is less than 30:70, the ability as a base supporting the rubber phase during dynamic vulcanization is insufficient, and the uniform dispersibility of the rubber phase is reduced. On the other hand, if the ratio of the PVC polymer exceeds 90:10, the basic hardness of the resin phase increases,
Large amounts of plasticizer must be added to achieve the target rubber hardness of the entire composition. Offset printing rollers manufactured from a composition with a large amount of plasticizer added are unfavorably affected by printing ink and a cleaning agent during actual printing, and changes with time such as hardness and outer diameter become large. .

The amount of the plasticizer varies depending on the weight ratio of the rubber phase: the resin phase, the weight ratio of the PVC-based polymer: TPU, the presence or absence and the type of other additives, but in general, the total of the NBR, the PVC-based polymer and the TPU. 10 to 100 parts by weight
It is added in an amount of 130 parts by weight, preferably 30 to 90 parts by weight. If the amount is within this range, the JIS-A of 20 to 40 will
A composition having good ink resistance, detergent properties, and extrudability while having hardness can be easily obtained.

The dynamic vulcanized elastomer composition used in the present invention may contain, if necessary, other thermoplastic elastomers, vulcanization accelerators, vulcanization activators, scorch inhibitors, antioxidants, antioxidants. , An ozone deterioration inhibitor, a processing aid, an inorganic filler, an inorganic pigment, an organic pigment, a stabilizer for PVC, a surfactant, a sub, and the like.

The dynamic vulcanized elastic composition used in the present invention comprises:
The above essential components and desired components can be produced by dynamic vulcanization under ordinary methods and conditions using a production apparatus such as an open roll, kneader, internal mixer, or twin screw extruder. Specific examples of the dynamic vulcanization are described in Examples below. Those skilled in the art can easily set vulcanization conditions according to the components and their compositions with reference to the descriptions in the examples.

The elastic roll for offset printing can also be manufactured by a usual method such as extrusion molding, and specific examples thereof will be described in Examples below.

[0025]

EXAMPLES Next, the component composition and properties of the elastic composition used in the present invention and the properties of the surface coating layer of the offset printing roller will be described with reference to Examples and Comparative Examples. It should be noted that the examples are for illustrative purposes and do not limit the scope of the invention or the manner in which the invention can be practiced.

Examples 1 to 4 and Comparative Examples 1 to 4 Using the components and compositions shown in Table 1, a dynamically vulcanized composition was obtained by the following method. Heat the internal mixer to 160 ° C,
NBR, PVC-based polymer, TPU, plasticizer and vulcanization aid were added and kneaded. In addition, a stabilizer is added to the used PVC-based polymer in advance, and a part of the plasticizer is PVC-mixed with a Henschel mixer or the like in order to assist miscibility with other polymers.
It is absorbed by a base polymer. Next, a vulcanizing agent and a vulcanization accelerator were added, and the mixture was heated and kneaded for 30 minutes while controlling the temperature so that the material temperature was maintained at 160 ° C., to obtain a dynamic vulcanization composition.

The obtained dynamic vulcanization composition was charged into an extruder, and a rubber tube having an outer diameter of 65 mm and an inner diameter of 38 mm was prepared.
Cut to length. This rubber tube was fitted into a roller core body having an outer diameter of 40 mm and treated with an adhesive. Further, in order to smooth the roller surface, the surface was polished with a rotary grindstone to an outer diameter of 60 mm, which was used as a printing roller sample.

With respect to the compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 4 and the manufactured rollers, the properties shown in the table were measured and evaluated by the following methods. 1. The smoothness of the extruded tube was visually observed. 2. The hardness was measured for the elastic roller according to JIS K6301. 3. The compression set was measured for the elastic roller according to JIS K6301. 4. The exothermicity was measured by the following simple measuring device. A metal roller of the same diameter is pressed against an elastic roller having a diameter of 60 mm so that the nip width becomes 6 mm, and the roller is rotated at 700 rpm.
After a lapse of time, the temperature of the elastic roller was measured. 5. For the printing ink resistance and the cleaning agent resistance, a 1 g composition sample was cut out from the surface of the elastic roller, immersed in volatile oil at normal temperature, taken out after 48 hours, and the change in weight was measured. This change in weight was taken as the swelling value. Further, the sample taken out from the volatile oil was left in an oven set at 50 ° C., and a change in weight was measured after 24 hours. This change in weight was used as the extracted value.

[0029]

[Table 1] Note: * TPU: Nipporan 4070 (Polyester polyol manufactured by Nippon Polyurethane Industry Co., Ltd.) / Millionate M
T (diphenylmethane-4,4'-diisocyanate manufactured by Nippon Polyurethane Industry Co., Ltd.) = 100 / 12.45
(Weight) curing reactant. (1): NBR manufactured by Nippon Synthetic Rubber Co., Ltd. (2): NBIR manufactured by Zeon Corporation (3): Straight PVC manufactured by Taiyo PVC Co., Ltd. (4): Ethylene-vinyl chloride copolymer manufactured by Taiyo PVC Co., Ltd. (5): Zinc stearate stabilizer manufactured by Sakai Chemical Industry Co., Ltd. (6): Barium-zinc stabilizer manufactured by Sakai Chemical Industry Co., Ltd. (7): Surface treated powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (8): Teuchimethylthiuram disulfide manufactured by Ouchi Shinko Chemical Co., Ltd. (9): Zinc oxide manufactured by Sakai Chemical Industry Co., Ltd. (10): Di (2-ethylhexyl) phthalate manufactured by Shin Nippon Rika Co., Ltd.

In Comparative Example 1, in which the weight ratio of the rubber phase / resin phase exceeds the range of the present invention, the resin phase as the base material cannot support the rubber phase during dynamic vulcanization, and the dynamic vulcanization composition I couldn't put it together.

The composition of Comparative Example 2 in which the weight ratio of the rubber phase / resin phase exceeds the range of the present invention has a low hardness of 20 to 40 JIS-A, and the heat generation of the roller is good. Poor printing ink and detergent properties, large compression set,
It was unsuitable as an elastic roller for offset printing.

The composition of Comparative Example 3 in which the weight ratio of the PVC polymer / TPU exceeds the range of the present invention is 20 to 40.
Although it has low hardness according to JIS-A, low compression set and low heat generation, it has poor printing ink and cleaning agent properties, and is unsuitable as an offset printing elastic roller.

The composition of Comparative Example 4 in which the weight ratio of PVC-based polymer / TPU exceeds the range of the present invention is 20 to 40 J
Although it has the low hardness of IS-A and has excellent printing ink and cleaning agent properties, it has poor compression set and heat generation, and is not suitable as an elastic roller for offset printing.

In contrast to these comparative examples, the compositions of Examples 1 to 4 have low hardness of 20 to 40 JIS-A, low compression set, low heat build-up, good printing ink and detergent properties, etc. Satisfy the performance as an elastic roller for offset printing.

[0035]

As apparent from the above description, NB
R, a PVC-based polymer, a TPU, and a plasticizer, a thermoplastic dynamic vulcanized elastic composition obtained by heating and kneading in the presence of a vulcanizing agent and a vulcanization accelerator are 20 to 40 JIS-A. Since it has low hardness and excellent compression set, heat generation, printing ink resistance and detergent properties, it is suitable for forming a surface coating layer of an elastic roller for offset printing. Furthermore, the thermoplastic dynamic vulcanized elastic composition of the present invention has good extrusion processability, does not require a long vulcanization step during molding, and is recyclable because it is thermoplastic. A composition.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 47/00 C08L 47/00 75/04 75/04 (56) References JP-A-2-269138 (JP, A) JP JP-A-47-1484 (JP, A) JP-A-9-291179 (JP, A) JP-A-10-237227 (JP, A) JP-A-7-279944 (JP, A) JP-A-57-117960 (JP) JP-A-51-52013 (JP, A) JP-A-55-49295 (JP, A) JP-A-53-27806 (JP, A) JP-A-57-95937 (JP, U) JP-A-57-95937 (JP, U) 2-31770 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41F 31/26 B41N 7/04 B41N 7/06 C08L 1/00-101/14

Claims (2)

(57) [Claims] 1. A core comprising a core and a surface coating layer formed thereon, wherein the surface coating layer is obtained by vulcanizing acrylonitrile-butadiene rubber, a vinyl chloride polymer, a thermoplastic polyurethane and a plasticizer. An elastic roller for offset printing, which is formed from a thermoplastic dynamic vulcanization elastic composition obtained by heating and kneading in the presence of an agent and a vulcanization accelerator. 2. The weight ratio of a rubber phase composed of acrylonitrile-butadiene rubber to a resin phase composed of a vinyl chloride polymer and thermoplastic polyurethane (rubber phase: resin phase) in the thermoplastic dynamic vulcanized elastic composition. ) Is 30: 70-
75:25, and the weight ratio of vinyl chloride polymer: thermoplastic polyurethane is 30:70 to 90:10.
2. The elastic roller for offset printing according to claim 1, wherein