JP3062502B1 - Compressible layer for printing blanket, method for producing the same, and printing blanket - Google Patents

Abstract

Kind Code: A1 A compressible layer for a printing blanket, which has excellent compression characteristics and durability, has a uniform thickness and internal structure, and does not cause a decrease in productivity of a printing blanket or an increase in manufacturing cost. A method of manufacture and a printing blanket incorporating the same are provided. SOLUTION: The compressible layer for a printing blanket and the method for producing the same include a sheet-like intermediate member including a layer of a rubber composition in which hollow microspheres are dispersed in a matrix rubber by directly contacting the intermediate member. Using a vulcanizer equipped with a member for heating and pressing, under the conditions of the following vulcanization pressure Pv [kgf / cm ² ] and vulcanization temperature Tv (° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the deformation temperature (° C.) when the hollow microspheres are heated at atmospheric pressure without pressing. ] It is characterized by heating for 1 to 50 minutes. The printing blanket is characterized by incorporating the compressible layer for the printing blanket described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanized rubber compressible layer having a porous structure, which is incorporated in a printing blanket, for a printing blanket, a method for producing the same, and the above-mentioned compressible layer for a printing blanket. It concerns printing blankets.

[0002]

2. Description of the Related Art In recent years, a so-called air type printing blanket has been widely used, in which a compressible layer having a porous structure, also made of an elastomer such as rubber, is provided under a surface printing layer made of an elastomer such as rubber. It is becoming more common. The air-type printing blanket has a lower compressive stress at the nip deformation caused by pressure contact with a plate cylinder, etc., and a lower compressive stress due to a change in the amount of distortion than the conventional solid type without a compressible layer. Since the fluctuation is small, it is excellent in shock absorption, and has an advantage that it has an excellent effect of preventing, for example, an impact generated when feeding a gear of a printing press from adversely affecting printing accuracy.

Further, in a solid type printing blanket, a so-called bulge is generated by stress concentration on a surface printing layer at a nip deformation portion, and misregistration due to circumferential elongation, poor paper feed, double, dot pattern, etc. However, according to the air-type printing blanket, the compressible layer acts to reduce the concentration of stress on the surface printing layer. There is also an advantage that occurrence can be prevented.

As the compressible layer having a porous structure in the above-mentioned air-type printing blanket, a layer in which sodium chloride particles are dispersed in a matrix rubber is formed into a layer, vulcanized, and then vulcanized. A continuous pore structure formed by the so-called leaching method, which is extracted with warm water, etc., and a foaming agent that decomposes by heating to generate gas is dispersed in matrix rubber to form a layer, and vulcanization is performed. It is known that the foaming agent is formed by foaming the foaming agent simultaneously with the vulcanization of the rubber by heating at the time, and has a closed pore structure, of which the latter, a compressible layer having a closed pore structure, In recent years, it has been attracting attention because of its superior durability and the like as compared with the former.

However, in the compressible layer having the above-mentioned independent pore structure, it is difficult to control the foaming of the foaming agent, and the size of each individual pore formed varies, or a plurality of pores are formed during the foaming process. As a result of the formation of huge voids by communicating with each other, there is a problem that the pore structure of the compressible layer becomes non-uniform and the compression characteristics vary, which adversely affects the printing characteristics. Therefore, in order to solve such a problem, it has been studied to form a compressible layer having an independent pore structure using hollow microspheres in which gas is sealed in a spherical shell made of a thermoplastic resin. . Since the above hollow microspheres are supplied in a form in which the shape and particle size are almost uniformly arranged, if this is dispersed in a matrix rubber to form a layer and vulcanize the matrix rubber, It was thought that a compressible layer having a uniform pore structure and no variation in compression characteristics could be obtained.

However, in the above configuration, if the matrix rubber is vulcanized by heating and pressing under the conventional conditions using a vulcanizer as in the past, a compressible layer having sufficient compression characteristics can be obtained. It became clear that there was none.
That is, the shell formed of the thermoplastic resin as described above is softened and melted by prolonged heating when vulcanizing the matrix rubber, and deformed by the pressurization during the vulcanization.
Because of the crushing, a uniform independent pore structure having a sufficient porosity was not formed in the compressible layer, and the compressive properties of the compressible layer were deteriorated.

[0007] Therefore, vulcanization of the matrix rubber without deforming or crushing the hollow microspheres has been studied, and various proposals have been made. For example, US Pat. No. 4,770,
No. 928 discloses that a matrix rubber formed by dispersing hollow microspheres into a layer is formed at a temperature of about 43 to 77 ° C., which is considerably lower than the deformation temperature of the hollow microspheres, for a long time of 1 to 12 hours. A method of forming a compressible layer by primary vulcanizing the matrix rubber without deforming or crushing the hollow microspheres by holding is disclosed.

Then, according to this method, the above-mentioned compressible layer is laminated with the other layers constituting the printing blanket and finally subjected to secondary vulcanization to produce a printing blanket in the same manner as in the conventional method. High temperature and high pressure are applied,
Even if the shell constituting the hollow microspheres softens and melts or disappears due to compatibility with the matrix rubber, the hollow microspheres have already been vulcanized to some extent during the primary vulcanization. The matrix rubber around the sphere is said to be able to produce a printing blanket with a high porosity, uniform, and a compressible layer exhibiting excellent compression characteristics in order to maintain the shape of the void where the hollow microsphere was. ing.

However, this method requires a very long time for the primary vulcanization of the matrix rubber as described above, so that the productivity of the compressible layer and, consequently, the printing blanket is significantly reduced. there were. In addition, in order to perform primary vulcanization of the matrix rubber at such a very low temperature, it is necessary to use a special vulcanization accelerator generally called a super-accelerator, which increases the production cost of a printing blanket. There was also a problem.

In the above publication, the deformation temperature of hollow microspheres is referred to as "the melting point of microcapsules (hollow microspheres)".
Although the term is used, as exemplified in the gazette,
The term is ambiguous because thermoplastic resins, such as, for example, copolymers of acrylonitrile and vinylidene chloride, do not have a well-defined melting point. According to the study by the inventors, for example, when the hollow microspheres are heated for a certain period of time (for example, about 30 minutes) under atmospheric pressure conditions that are not pressurized, such as in an oven maintained at a certain temperature, The minimum temperature at which the phenomenon in which the shell softens and melts in time and a number of hollow microspheres aggregate and integrate by fusion occurs is referred to as the “melting point” in the above-mentioned publication, or 2 below. In this specification, the heat-resistant temperature of the hollow microspheres is referred to as the deformation temperature of the hollow microspheres, specifically, the hollow microspheres. Is expressed as the deformation temperature when heated at atmospheric pressure without pressurization.

Japanese Patent Application Laid-Open No. 3-244595 discloses a method of improving the above-mentioned method, in which a matrix rubber layer is formed by:
It is brought into contact with a drum heated at a temperature lower than the deformation temperature of the hollow microspheres and at the highest possible temperature (about 100 ° C. or less in the description in the specification) or heated to the above temperature. It describes a method of vulcanizing by hanging in an atmosphere. And
It is described that the vulcanization time can be shortened by adopting such a method as compared with a case where vulcanization is performed by leaving the method alone.

However, it is not clear in the above publications how much the vulcanization time can be reduced by adopting this method, but it is not clear. From the description in the gazette that it can be shortened, even if it can be shortened, it is expected that the vulcanization of the compressible layer still requires about 1 to 10 hours or more, and it is likely to be. Then the problem of low productivity of the compressible layer, and consequently of the printing blanket, seems to remain unsolved.

In the above method, the vulcanization temperature is still as low as 100 ° C. or lower, so that the vulcanization accelerator is also the above-mentioned super accelerator (“1.
"A strong substance that vulcanizes rubber at temperatures below 00 ° C" means a super-accelerator), and the cost of producing a printing blanket based on the use of a super-accelerator is reduced. The costly problem remains unresolved. So, in order to solve these problems,
In Japanese Patent Publication No. Hei 7-505341, high heat-resistant hollow microspheres having a deformation temperature of 135 ° C. or higher are used, and the primary vulcanization temperature of the matrix rubber is also lower than the deformation temperature of the hollow microspheres. Although it is a low temperature, it has been proposed to set the temperature to about 80 to 150 ° C., which is higher than before.

As the effect, the above publication discloses that the time of primary vulcanization can be reduced to 1 to 6 hours, and that a general-purpose vulcanization accelerator is used without using the special super accelerator as described above. It has been claimed that a compressible layer can be formed by pressing.

[0015]

However, even in the above method, since the vulcanization time is still longer than one hour, the amount of heat applied to the hollow microspheres during vulcanization is large, and the temperature of the primary vulcanization of the matrix rubber is also increased. And the deformation temperature of the hollow microspheres are close to each other, so that during the actual vulcanization, the vulcanization reaction of the matrix rubber, the softening of the shell, the deformation of the hollow microspheres due to melting, and the crushing occur almost simultaneously. The fact that they proceed in a competitive manner has been clarified by the inventors' studies.

For example, a layer of matrix rubber in which hollow microspheres are dispersed, which is a base of the compressible layer, is wound in a roll shape together with a single-layer base fabric supporting the layer, and vulcanized in a vulcanizing can. When primary vulcanization of the compressible layer is performed by a method that may greatly vary the amount of heat received by the matrix rubber layer, as in the case of vulcanization, the surrounding matrix rubber must be sufficient in the same compressible layer. Although the hollow microspheres have already been deformed and crushed, or the hollow microspheres have not been deformed or crushed, the surrounding matrix rubber has not been sufficiently vulcanized. As a result, there are places where the hollow microspheres are deformed and crushed during the secondary vulcanization, and as a result, the porosity of the compressible layer in the printing blanket is greatly reduced, or it varies from place to place, and the compressive properties deteriorate. You It has been found that Les.

The main object of the present invention is to exhibit excellent compression characteristics and excellent durability due to having a uniform closed pore structure, to be able to produce efficiently in a short time, and to use a special compound such as a super accelerator. It is an object of the present invention to provide a novel compressible layer for a printing blanket, which does not require a chemical and does not reduce the productivity of the printing blanket or increase the production cost. Another object of the present invention is to
It is an object of the present invention to provide a novel production method for producing such a compressible layer for a printing blanket.

Still another object of the present invention is to provide a novel printing blanket incorporating the above-mentioned compressible layer for a printing blanket.

[0019]

Means for Solving the Problems and Effects of the Invention In order to solve the above-mentioned problems, the present inventors have proposed a thin vulcanized material having a constant thickness, such as a sheet, as compared with the conventional one. Attention was paid to a vulcanizing apparatus provided with a member that can be vulcanized in a shorter time and that is heated and pressed in direct contact with the material to be vulcanized. Using the above vulcanizing device, vulcanization that does not require a special agent such as the above-described super-accelerator, and can vulcanize only the matrix rubber without deforming or crushing the hollow microspheres. As a result of repeated examinations to find out the conditions, the present invention was completed.

That is, the compressible layer for a printing blanket of the present invention is a sheet-shaped intermediate layer including a layer of a rubber composition in which hollow microspheres having a shell of a thermoplastic resin are dispersed in an unvulcanized matrix rubber. The following vulcanization pressure Pv [kgf / cm ² ] and the vulcanization temperature T were obtained by using a vulcanizer equipped with a member for heating and pressing the member by directly contacting the member with the intermediate member.
Under the condition of v (° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the deformation temperature when the hollow microspheres are heated at atmospheric pressure without pressing. ° C). ] It is characterized by being formed by vulcanizing the layer of the rubber composition by heating for 1 to 50 minutes.

The method for producing a compressible layer for a printing blanket according to the present invention comprises the steps of (1) dispersing hollow microspheres having a shell of a thermoplastic resin in an unvulcanized matrix rubber to produce a rubber composition. And (2) laminating the rubber composition in layers on at least one layer of base fabric to form a sheet-like intermediate member, and (3) directly contacting the intermediate member with the intermediate member The following vulcanization pressure Pv [kgf / cm ² ] and vulcanization temperature Tv were measured using a vulcanizer equipped with members for heating and pressing.
(° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the deformation temperature (° C.) when the hollow microspheres are heated at atmospheric pressure without pressing. ). ] A step of heating for 1 to 50 minutes to vulcanize the layer of the rubber composition.

Furthermore, the printing blanket of the present invention is characterized in that the above-mentioned compressible layer for the printing blanket of the present invention is formed by vulcanizing the whole while being laminated with other layers constituting the printing blanket. Is what you do. According to the present invention, as described above, a vulcanizing apparatus including a member for heating and pressing a sheet-shaped intermediate member including a layer of an unvulcanized rubber composition by directly contacting the intermediate member. Under the conditions of the above-mentioned specific vulcanization pressure Pv and vulcanization temperature Tv,
The vulcanization for a shorter period of time, up to 50 minutes, forms a compressible layer for printing blankets.

In such a short time vulcanization, the softening of the shell, deformation of the hollow microspheres due to melting,
Since phenomena such as crushing hardly progress, the formed compressible layer for printing blanket is uniform and shows excellent compression characteristics. In addition, since such a compressible layer for printing blanket has an independent pore structure formed by a large number of hollow microspheres as described above, it has excellent durability compared to a conventional one having a continuous pore structure. I have.

Further, since such a compressible layer for a printing blanket is efficiently produced by the above-described short-time vulcanization, not only is there no risk of lowering the productivity of the printing blanket, It is also possible to improve productivity as compared with. Moreover, the above-mentioned vulcanization is performed at a temperature not lower than the deformation temperature Td (° C.) when the hollow microspheres are heated at atmospheric pressure without pressurization and higher than the deformation temperature Td (° C.) by 50 ° C. Since it is performed at a relatively high temperature and does not require a special agent such as a super accelerator, there is no possibility of increasing the manufacturing cost of a printing blanket.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. First, the compressible layer for a printing blanket of the present invention will be described based on a method for producing the same. In the present invention, first, on a base cloth, a layer of a rubber composition in which hollow microspheres are uniformly dispersed in an unvulcanized matrix rubber, which is a source of a compressible layer for a printing blanket, is laminated to form a sheet. Is manufactured.

The sheet-shaped intermediate member is formed in an appropriate size and shape. For example, the intermediate member may be formed in advance to a predetermined length according to the size of one printing blanket. However, if a continuous vulcanizer is used as the vulcanizing device, the continuous vulcanizer can vulcanize the material to be vulcanized continuously regardless of its length. Considering the productivity and the productivity of the printing blanket, the intermediate member is preferably formed in a long sheet shape in which a large number of printing blankets are continuous.

The above-mentioned long intermediate member may be obtained by dissolving a rubber paste obtained by dissolving the above-mentioned rubber composition in a suitable solvent such as toluene, methyl ethyl ketone, or the like, on a long belt-like base cloth via a vulcanizing adhesive, or It is directly applied and dried directly using, for example, a knife coater, a roll coater, a spray coater, a flow coater, or the like, or, for example, as described in FIG. 1 of JP-A-59-14995. , A long strip of base fabric, continuously,
It is manufactured by dipping in the above-mentioned rubber paste, pulling up and drying.

As the matrix rubber constituting the rubber composition, various rubbers can be mentioned. Particularly, in consideration of the resistance to inks and cleaning liquids, those having excellent oil resistance are preferable. Examples thereof include, but are not limited to, acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), urethane rubber (U), and acrylic rubber (ACM). Examples of the hollow microspheres include, for example, the aforementioned U.S. Pat. No. 4,770,928 and JP-A-3-244595.
Various known hollow microspheres having a shell formed of a thermoplastic resin, such as those disclosed in Japanese Patent Application Laid-Open Publication No. 7-505341 and Japanese Patent Application Laid-Open No. 7-505341, can be used.

In particular, considering oil resistance to printing inks, homopolymers of polymerizable monomers such as vinylidene chloride and (meth) acrylonitrile,
A copolymer containing these monomers or a tertiary or higher multi-component copolymer containing these monomers is preferred. Although the particle size of the hollow microspheres is not particularly limited, the average particle size of the hollow microspheres is preferably about 5 μm in order to form a uniform closed pore structure and impart good compression characteristics to the compressible layer for a printing blanket. It is preferably about 10 to 200 μm.
Incidentally, the particle size, in the case of unfoamed hollow microspheres described below,
This is the particle size after heating and foaming.

Specific examples of the hollow microspheres include, for example, hollow microspheres of the Expancel series manufactured by Nobel or hollow microspheres manufactured by Matsumoto Yushi Seiyaku Co., Ltd. Each of these hollow microspheres is an unfoamed one in which an organic solvent that forms a void is sealed in a shell of a thermoplastic resin, and the above-mentioned organic solvent is vaporized by heating to form an inner shell. And foamed ones having voids formed therein are supplied, and any of these can be used in the present invention.

When the former, unfoamed hollow microspheres are used, (1) the rubber composition is dispersed on the matrix rubber to form a rubber composition, and (2) the rubber composition is dispersed on the base cloth. Before vulcanizing by laminating in layers, or (3) at the time of vulcanizing the layer of the rubber composition, the organic solvent in the shell is vaporized by heating to form the hollow microspheres. It is preferred that the particles be foamed up to the particle size.

The mixing ratio of the hollow microspheres in the rubber composition is not particularly limited, but considering the compression characteristics of the formed compressible layer for printing blanket, the hollow microspheres M in the foamed state with respect to the matrix rubber R are considered. The volume ratio M / R is preferably in the range of M / R = 20/80 to 80/20, particularly preferably M / R = 70/30 to
Preferably it is in the range of 30/70. The rubber composition, in addition to the two components, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator, a vulcanization retarder, and other components for vulcanizing the rubber are added, Various additives such as an antioxidant, a reinforcing agent, a filler, a softener, and a plasticizer are added as necessary. The amounts of these additives may be the same as in the conventional case. Specific compounds of these additives will be exemplified later. Among them, as the vulcanization accelerator, a special super accelerator is unnecessary as described above, and a general-purpose vulcanization accelerator as described later is It is preferably used. However, except for cost, there is no reason to exclude the super-promoter, so that a super-promoter may be used if no cost problem arises.

As the base fabric on which the above rubber composition is laminated, a woven fabric such as cotton, polyester, rayon or the like is used as in the prior art. Next, as described above, the above-mentioned intermediate member is vulcanized using a vulcanizing apparatus provided with a member for directly contacting the intermediate member and heating and pressing the same, using the following vulcanization pressure Pv [kgf / c
m ² ] and the vulcanization temperature Tv (° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the atmospheric pressure without pressurizing the hollow microspheres. Is the deformation temperature (° C.) when heated. ] Heat and cure for 1 to 50 minutes.

As described above, the deformation temperature Td (° C.) is, as described above, for example, when the hollow microspheres are not pressurized, such as in an oven maintained at a constant temperature, for a predetermined time (for example, 30 minutes). The degree is defined as the minimum temperature at which the shell softens and melts within the above-mentioned time when heated, and a phenomenon in which a large number of hollow microspheres aggregate and integrate by fusion occurs. In the present invention, among the vulcanization conditions, the vulcanization pressure Pv is limited to the range of 0 <Pv ≦ 3.0 kgf / cm ² for the following reason.

That is, the vulcanization pressure Pv is 3.0 kgf / cm
If it exceeds ² , the hollow microspheres will be deformed and crushed by such high pressure, and the porosity of the compressible layer for printing blanket will be greatly reduced, or will vary depending on the location, and the compression characteristics will be deteriorated. . On the other hand, the vulcanization pressure Pv is 0 kg
f / cm ² , that is, under atmospheric pressure without pressurization, the hollow microspheres expand unevenly due to the heat during vulcanization, and the internal structure of the compressible layer for printing blanket becomes uneven. Variations occur.

The vulcanization pressure Pv is determined by the thickness of the compressible layer.
The size, size and dispersion of hollow microspheres
Even more uniform thickness and uniform internal structure with less sticking
Forming a compressible layer for a printing blanket having
Considering the above, the smaller the value is within the above range,
Preferably, 0.2 kgf / cm^TwoBelow, especially 0.07
kgf / cm^TwoIt is preferred that: Also, the vulcanization pressure
The lower limit of Pv is not particularly limited for the above reasons.
Of the accuracy of pressurization in the vulcanizer
And about 0.01kgf / cm ^TwoIt is about.

In the present invention, among the vulcanization conditions, the vulcanization temperature Tv (° C.) is equal to or higher than the deformation temperature Td (° C.) when the hollow microspheres are heated under atmospheric pressure without pressing. The reason why the temperature is limited to a range of 50 ° C. or lower than the deformation temperature Td (° C.) and the vulcanization time is limited to a range of 1 to 50 minutes is as follows. That is,
When one of the vulcanization temperature Tv (° C.) and the vulcanization time exceeds the above range, the hollow microspheres are
Such high-temperature and long-time heating causes deformation and crushing, so that the porosity of the compressible layer for a printing blanket is significantly reduced or varies depending on the location, and the compression characteristics are deteriorated.

On the other hand, if any one of the vulcanization temperature Tv (° C.) and the vulcanization time is less than the above ranges, the vulcanization of the matrix rubber becomes insufficient and the next step During the secondary vulcanization, the hollow microspheres may be deformed or crushed, causing the porosity of the compressible layer for the printing blanket to decrease significantly or to vary from place to place, deteriorating the compression properties. Resulting in. Among the above, the vulcanization temperature Tv (° C.) is such that the matrix rubber alone is vulcanized without almost deforming or crushing the hollow microspheres, thereby forming a compressible layer for a printing blanket exhibiting uniform and excellent compression characteristics. Taking this into consideration, it is particularly preferable that Tv ≦ Td + 40 ° C., and it is more preferable that Tv ≦ Td + 35 ° C. be within the above range.

In consideration of efficiently forming the compressible layer for a printing blanket in a short time, the above-mentioned vulcanization temperature Tv (° C.) is preferably within the above range, and more preferably, Td + 10 ° C. ≦ Tv. It is more preferable that Td + 15 ° C. ≦ Tv.

The vulcanization time is preferably at least 3 minutes in the above range, considering that the matrix rubber is surely and uniformly vulcanized. In consideration of the productivity of the compressible layer for a printing blanket and the like, the vulcanization time is preferably within the above range, particularly preferably 40 minutes or less. By vulcanizing the sheet-shaped intermediate member under the above vulcanization conditions, as a vulcanizing apparatus for producing a compressible layer for a printing blanket, a member that directly contacts and heats and pressurizes the intermediate member, Any of various types of vulcanizing apparatuses capable of vulcanizing the intermediate member under the above conditions can be used.

However, in order to perform uniform pressurization over the entire range of the vulcanization pressure Pv, as shown in FIG. 1, for example, heat rotating at a constant speed in a direction indicated by a solid-line arrow in the figure. Generally, Adamson (A) comprises a roller 1 and an endless belt 2 which is pressed against the roller at a constant pressure and rotates in synchronization with the rotation of the heat roller in a direction indicated by a dashed line arrow in the figure.
damson) (US) equipment name from Roto-Cur
e) or Berstorff (Germany)
A continuous vulcanizer called an AUMA type from the name of the apparatus is preferably used.

Examples of the belt 2 include a metal belt from a thin metal plate, a metal belt knitted with metal wires, and a composite belt whose surface on the product side is covered with heat-resistant rubber, or a vulcanized rubber belt reinforced with a base cloth. Any of the belts normally used in the continuous vulcanizer of the above can be used. However, as described above, the vulcanization pressure Pv is 0.2 kgf / cm ²
In a low-pressure region such as the following, when the above-mentioned conventional belts are used, since all of these belts are rigid in the thickness direction, that is, the direction of pressing the intermediate member, uniform pressing is accurately performed. This is not easy, and the vulcanization pressure varies, and in particular, the thickness of the compressible layer tends to vary slightly.

Therefore, the vulcanization pressure Pv is 0.2 kgf / cm
When vulcanizing at a low pressure of ² or less, it is preferable to use a belt having a felt shape, such as felt manufactured by various manufacturing methods and the like, instead of the conventional belt. Since the felt-shaped belt has high flexibility and elasticity in its thickness direction, it can be uniformly and accurately applied under a low pressure condition of vulcanization pressure Pv of 0.2 kgf / cm ² or less. Pressure is possible, and as described above, the unevenness of the thickness of the compressible layer, the shape and size of the hollow microspheres, the unevenness of the dispersion state, etc. are suppressed, and even more, it has a uniform thickness and a uniform internal structure. It is suitable for producing a compressible layer for a printing blanket.

As the belt in the form of felt, any of various felts such as woven felt, press felt, needle felt, etc. classified according to the production method, and nonwoven fabrics having an appearance similar to felt can be used. It is possible. The felt-shaped belt 2 has high flexibility and elasticity in the thickness direction as described above, so that uniform pressurization can be accurately performed over the entire range of the above-described vulcanization pressure Pv. Although the specification is not limited to this, it is preferable that the thickness is about 3 to ²⁰ mm and the weight per unit area is about 500 to 10000 g / m ² .

In the drawings, reference numerals 21 to 23 denote rollers for rotating the belt 2 at a constant speed while pressing the belt 2 against the heat roller 1 at a constant pressure as described above.
Using the continuous vulcanizer of the figure, unvulcanized as described above,
In order to vulcanize the intermediate member 3 in the form of a long sheet, first, the intermediate member 3 is moved between the heat roller 1 and the belt 2 along the length direction as shown by a white arrow in the drawing. Insert continuously. Then, the intermediate member 3 wound between the two members is continuously heated by the heat of the heat roller 1 while being pressed to a constant pressure by the pressing force of the belt 2 against the heat roller 1. You.

By this heating, the unvulcanized rubber composition of the intermediate member 3 is continuously vulcanized, and a compressible layer for a printing blanket made of vulcanized rubber is continuously formed. As shown by black arrows, the toner is continuously discharged from between the heat roller 1 and the belt 2. When the continuous vulcanizer shown in the above figure is used, the vulcanization temperature Tv among the vulcanization conditions described above.
(° C.) is adjusted within the above range by adjusting the heating temperature of the heat roller 1. For example, in the case of the heat roller 1 of a method of heating with heated steam, the temperature of the heated steam may be adjusted within the above range.

The vulcanization time is defined by the distance that the intermediate member 3 is pressed against the heat roller 1 and the rotation speed of the heat roller 1, and the pressure contact distance is substantially dependent on the size of the apparatus. In general, it is preferable to adjust the vulcanization time by changing the rotation speed of the heat roller 1 and the belt 2 that rotates together with the heat roller 1 because the speed cannot be changed greatly. Further, the vulcanization pressure Pv is adjusted by changing the pressing force of the belt 2 against the heat roller 1. Specifically, for example, a member that adjusts the positional relationship between the rollers 21 to 23 and the heat roller 1 or a member that adjusts the tension of the belt 2 is arranged between the rollers 22 and 23 (not shown). , The belt 2
By changing the tension of the belt 2,
The vulcanization pressure Pv is adjusted by changing the pressure applied to the heat roller 1. When the felt-shaped belt is used as the belt 2, the vulcanization pressure Pv can be finely adjusted by changing the specification.

As the vulcanizing apparatus, for example, a hot press or the like can be used in addition to the continuous vulcanizing machine. The surface of the vulcanizable printing blanket compressible layer may be polished, for example, to adjust its surface roughness. Next, the printing blanket of the present invention will be described. The printing blanket of the present invention is obtained by continuously laminating a laminate of a compressible layer for a printing blanket made of vulcanized rubber and a base fabric, which is manufactured continuously as described above, with other layers constituting the printing blanket. It is manufactured by vulcanizing the whole.

As the other layers constituting the printing blanket, there may be mentioned various conventionally known layers such as a plurality of base fabrics or a layer of a rubber composition which forms a surface printing layer. Among them, as the base fabric, cotton as described above,
Examples include woven fabrics such as polyester and rayon. In consideration of the productivity of the printing blanket and the like, these layers are also formed in a long shape in which a large number of printing blankets are continuous as in the case of the intermediate member, and are continuously laminated with the laminate. Preferably.

It is to be noted that, among the above-mentioned respective layers, the base cloths, or the already vulcanized laminate (a laminate of a compressible layer for a printing blanket made of vulcanized rubber and a base cloth) and a base cloth, etc. For example, the vulcanizing adhesive is laminated by so-called vulcanizing adhesive in which components such as a vulcanizing agent and a vulcanization accelerator are blended with oil-resistant rubber such as NBR and ACM, and vulcanizing adhesive is cured by whole vulcanization. It is preferable to bond and integrate by sulfurizing. In the same manner as described above, the rubber composition layer serving as the base of the surface printing layer may be formed, for example, by applying a rubber paste obtained by dissolving the rubber composition in an appropriate solvent directly on the base or via the vulcanized adhesive. It is formed by coating and drying continuously.

Then, the rubber composition layer is vulcanized by the overall vulcanization, and is adhered to and integrated with the base, thereby forming a surface printing layer. As the matrix rubber constituting the rubber composition for the surface printing layer, oil-resistant rubbers such as NBR, CR, U, and ACM are also preferably used, and hydrogenated NBR can be used. Mixtures of various rubbers and polysulfide rubber (T) can also be used.

In the same manner as described above, the rubber composition for the surface printing layer contains components for vulcanizing the rubber, such as a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, and a vulcanization retardant. Besides being added,
Various additives such as an antioxidant, a reinforcing agent, a filler, a softener, a plasticizer, and a tackifier may be appropriately compounded. For the overall vulcanization, vulcanization cans may be used as in the past.However, while improving the productivity of the printing blanket, the vulcanization is performed uniformly without vulcanization, and a printing blanket having uniform characteristics is manufactured. In this case, it is preferable to use the continuous vulcanizer or hot press.

The conditions of the whole vulcanization using the above-mentioned continuous vulcanizer or hot press are not particularly limited. this is,
Even if high temperature and high pressure are applied during the overall vulcanization, the shells constituting the hollow microspheres may be softened and melted, or may be dissolved in the matrix rubber and disappear, but the continuous vulcanization The matrix rubber around the hollow microspheres, which has already been vulcanized to a certain extent, has characteristics of the compressible layer for the printing blanket incorporated in the printing blanket in order to maintain the shape of the void where the hollow microspheres were located. Is hardly affected.

However, if the vulcanization pressure during the overall vulcanization is too high, the matrix rubber itself, which maintains the shape of the voids, may be crushed and the voids may be deformed or crushed. Is preferably in the range of about 3 kgf / cm ² or less. After the vulcanization, if necessary, the surface of the surface printing layer is polished to produce a printing blanket.

Among the additives added to each layer constituting the printing blanket, examples of the vulcanizing agent include sulfur, organic sulfur-containing compounds, organic peroxides and the like. N, N'-dithiobismorpholine and the like can be mentioned, and as the organic peroxide, for example, benzoyl peroxide, dicumyl peroxide and the like can be mentioned. Although a super-accelerator can be used as the vulcanization accelerator, as described above, the vulcanization temperature is high in the present invention. Therefore, considering the production cost of a printing blanket, etc., it is mainly a general-purpose vulcanization accelerator. It is preferred to use

General-purpose vulcanization accelerators include, for example, thiuram vulcanization accelerators such as tetramethylthiuram disulfide and tetramethylthiuram monosulfide; zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, and dimethyldithiocarbamine. Dithiocarbamic acids such as sodium silicate and tellurium diethyldithiocarbamate;
Organic accelerators such as thiazoles such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfenamide; thioureas such as trimethylthiourea and N, N'-diethylthiourea; or slaked lime and magnesium oxide; Titanium oxide, litharge (Pb
O) and the like.

Examples of the vulcanization accelerator include metal oxides such as zinc white, stearic acid, oleic acid, and the like.
And fatty acids such as cottonseed fatty acids. Examples of the vulcanization retarder include aromatic organic acids such as salicylic acid, phthalic anhydride and benzoic acid; N-nitrosodiphenylamine,
And nitroso compounds such as -nitroso-2,2,4-trimethyl-1,2-dihydroquinone and N-nitrosophenyl-β-naphthylamine.

Examples of antiaging agents include imidazoles such as 2-mercaptobenzimidazole; phenyl-α-naphthylamine, N, N′-di-β-naphthyl-
amines such as p-phenylenediamine and N-phenyl-N'-isopropyl-p-phenylenediamine; di-t
And phenols such as -butyl-p-cresol and styrenated phenol. As a reinforcing agent, carbon black is mainly used, and inorganic reinforcing agents such as silica-based or silicate-based white carbon, zinc white, surface-treated precipitated calcium carbonate, magnesium carbonate, talc, clay, and the like. Organic reinforcing agents such as malonindene resin, phenolic resin and high styrene resin (styrene-butadiene copolymer having a high styrene content) can also be used.

Examples of the filler include inorganic fillers such as calcium carbonate, clay, barium sulfate, diatomaceous earth, mica, asbestos, and graphite, and organic fillers such as asphalts, styrene resin, and glue. Examples of the softener include fatty acids (such as stearic acid and lauric acid), cottonseed oil, tall oil,
Various softening agents of vegetable oil type, mineral oil type, and synthetic type, such as asphalt substances and paraffin wax, may be mentioned.

Examples of the plasticizer include various plasticizers such as dibutyl phthalate, dioctyl phthalate and tricresyl phosphate. Examples of the additives other than the above include a tackifier, a dispersant, and a solvent. As described above in detail, the compressible layer for a printing blanket of the present invention exhibits excellent compression characteristics and durability because the thickness and the internal structure of the layer are uniform.

The compressible layer for a printing blanket of the present invention can be efficiently produced in a short time, and does not require a special agent such as a super-promoting agent. There is no risk of increasing costs. Further, the printing blanket of the present invention has excellent compression characteristics and durability since the printing blanket compressible layer is incorporated. Further, according to the production method of the present invention, the compressible layer for a printing blanket can be efficiently produced.

[0062]

The present invention will be described below based on examples and comparative examples. << Measurement of Deformation Temperature of Hollow Microspheres >> As hollow microspheres, all manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., product number F50
D [unfoamed hollow microspheres whose shell is made of a copolymer of acrylonitrile and methyl methacrylate], and F50
E (also foamed hollow microspheres having an average particle size of 50 μm, the shell of which is made of a copolymer of acrylonitrile and methyl methacrylate), under atmospheric pressure where each hollow microsphere is not pressurized. The deformation temperature (° C.) at the time of heating was measured by the method using the oven described above.

That is, a predetermined amount of hollow microspheres
Weigh into trays, put each tray in a hot-air oven maintained at a constant temperature, and agglomerate a large number of hollow microspheres by softening and melting by melting of shell under atmospheric pressure without pressurization 5 to determine whether the phenomenon of integration has occurred
Observed every minute. The above observation is repeated, for example, while changing the set temperature of the oven by 5 ° C. (the hollow microspheres are replaced with new ones each time). The lowest temperature at which the phenomenon of transformation occurs is determined and the deformation temperature Td
(° C.).

As a result, it was confirmed that the deformation temperature Td of both F50D and F50E was 120 ° C. << Compressive Layer for Printing Blanket >> Examples 1-3 <Preparation of Rubber Glue> The following components were mixed with an appropriate amount of toluene, and then this mixture was mixed with unfoamed hollow microspheres (Matsumoto Oil & Fat, supra). When F50D manufactured by Pharmaceutical Co., Ltd.] is assumed to have an average particle size after foaming of 50 μm, the components are added in the same volume as NBR, and then further mixed, and then mixed with the hollow microspheres. Was uniformly dispersed to prepare a rubber paste.

[0065] <Preparation of Intermediate Member> The rubber paste prepared as described above is continuously applied on a long-strip cotton cloth having a width of 200 cm as a base cloth and dried to obtain an unvulcanized rubber composition having a thickness of 0.20 mm. A long sheet-like intermediate member, which is a laminate of the product layer and the base cloth, was formed. <Preparation of Compressible Layer for Printing Blanket> Felt-shaped belt [made of aramid fiber, having a thickness shown in FIG. 8mm, weight 30 per unit area
00g / m ² ], the vulcanization pressure Pv [vv shown in Table 1 was applied to the intermediate member prepared above under the conditions of vulcanization temperature Tv = 150 ° C. and vulcanization time of 5 minutes. kgf / c
m ² ], while continuously heating and foaming the hollow microspheres, the rubber composition layer is continuously vulcanized to obtain a laminate of a vulcanized rubber printing blanket compressible layer and a base fabric. Was prepared.

Examples 4 to 7 and Comparative Example 1 The same thickness as in Examples 1 to 3, 0.20 m
The intermediate member in the form of a long sheet, which is a laminate of the unvulcanized rubber composition layer of m and the base cloth, has a structure shown in FIG. The vulcanization pressure Pv [kgf / cm ² shown in Table 1 was used under the conditions of a vulcanization temperature Tv = 150 ° C. and a vulcanization time of 5 minutes using a continuous vulcanizer equipped with a fiber reinforced rubber. The rubber composition layer is continuously vulcanized while the hollow microspheres are foamed by continuous heating to produce a laminate of a compressible layer for a vulcanized rubber printing blanket and a base fabric. did.

Comparative Example 2 The same thickness as in Examples 1 to 3, 0.20 m
m in a hot air oven held at 150 ° C. in a state where a long sheet-shaped intermediate member, which is a laminate of the unvulcanized rubber composition and the base cloth, is cut to a predetermined length. let me in,
The rubber composition layer is vulcanized while heating and foaming the hollow microspheres for 5 minutes under atmospheric pressure without pressurization, and the compressible layer for the printing blanket made of vulcanized rubber is laminated with the base fabric. The body was made.

Comparative Examples 3 and 4 The same thickness as in Examples 1 to 3, 0.20 m thick
m of a non-vulcanized rubber composition layer and a base sheet, a long sheet-shaped intermediate member is wound around a metal drum having a diameter of 1.5 m for 20 turns to form a vulcanized can. Put, can pressure 2
kgf / cm ² , final temperature of 150 ° C., vulcanization time 5 hours. The rubber composition layer is vulcanized while foaming the hollow microspheres by foaming to form a vulcanized rubber printing blanket. A laminate of the compressible layer and the base fabric was produced.

The portion (winding layer) at the beginning of winding on the metal drum in the above-mentioned laminate was designated as Comparative Example 3, and the portion at the end of winding (outermost layer) was taken as Comparative Example 4. Example 8 Foamed hollow microspheres (F50E manufactured by Matsumoto Yushi Seiyaku Co., Ltd., average particle size: 50 μm) were used, and the same volume as NBR of each component was added, and continuous hollow microspheres were added. Vulcanization pressure of continuous vulcanization by vulcanizer is 1.5 kgf
/ Cm, except ² that has been set in Examples 4-7, Comparative Example 1
In the same manner as described above, a laminate of a vulcanized rubber compressible layer for printing blanket and a base fabric was prepared.

Examples 9 to 11, Comparative Examples 5 and 6 The same thickness as in Examples 1 to 3, 0.20 m
A long sheet-shaped intermediate member, which is a laminate of an unvulcanized rubber composition layer of m and a base fabric, has a structure shown in FIG. Vulcanization temperature Tv [° C.] and vulcanization time shown in Table 2 under the conditions of vulcanization pressure Pv = 1.5 kgf / cm ² using a continuous vulcanizer equipped with the obtained fiber reinforced rubber. While continuously heating in [minutes] to expand the hollow microspheres, the rubber composition layer is continuously vulcanized to form a laminate of a vulcanized rubber printing blanket compressible layer and a base fabric. Was prepared.

Example 12 The same thickness as 0.20 m as produced in Examples 1 to 3 above.
m, a long sheet-shaped intermediate member, which is a laminate of an unvulcanized rubber composition layer and a base cloth, is cut into dimensions of one blanket, and the vulcanization temperature is determined using a hot press. Tv = 15
0 ° C., vulcanization pressure Pv = 1.5 kgf / cm ² , vulcanization time 5
While heating under the conditions of minutes to foam the hollow microspheres,
The layer of the rubber composition was vulcanized to prepare a laminate of a compressible layer for a printing blanket made of vulcanized rubber and a base fabric.

The following observations and measurements were made on the laminates produced in the above Examples and Comparative Examples. Observation of Appearance The appearance of the laminates produced in the respective Examples and Comparative Examples, particularly on the side of the compressible layer for printing blanket, was observed. The appearance was evaluated according to the following criteria. A: No irregularities are seen on the surface. Very good appearance.

A: Almost no irregularities were observed on the surface. Good appearance. ×: Large irregularities are generated on the surface. Poor appearance. Observation of Internal Structure The laminates of Examples and Comparative Examples were cut in the width direction, and the cut surfaces, particularly the shapes of voids, were observed with a microscope.
Then, the quality of the uniformity of the internal structure was evaluated based on the following criteria.

A: The voids are spherical and the size is very uniform. Very good internal structure. ：: The void is spherical and its size is almost uniform. Good internal structure. Δ: A part of the gap is deformed and the size is not uniform. Internal structure failure. ×: The void is deformed and crushed. Extremely bad internal structure. Measurement of Thickness Difference Thickness in the width direction of the laminate of each Example and Comparative Example was 100
It was measured at mm intervals. Then, the difference between the two values was determined from the maximum value and the minimum value of the thickness, and the uniformity of the thickness was evaluated.

The above results are shown in Tables 1 and 2. The symbols in the vulcanization method column in the following table indicate the following vulcanization methods, respectively. OV: Oven vulcanization CVF: Continuous vulcanization using felt belt CVR: Continuous vulcanization using fiber reinforced rubber belt HP: Hot press KV: Can vulcanization

[0076]

[Table 1]

[0077]

[Table 2]

From the results of Comparative Examples 3 and 4 in the table, in can vulcanization,
It has been found that depending on the location of the winding, the porous structure of the produced compressible layer for a printing blanket greatly varies. Also, from the results of Comparative Example 2, it was found that under atmospheric pressure conditions where no pressure was applied, a compressible layer for a printing blanket having a uniform porous structure could not be produced due to excessive and uneven expansion of the hollow microspheres.

Further, from the results of Comparative Example 1, when the vulcanization pressure Pv exceeds 3.0 kgf / cm ² even when a continuous vulcanizer is used, a porous structure having a sufficient porosity is obtained. It was found that it was not possible to produce a printing blanket compressible layer having the same. Further, from the results of Comparative Example 5, even when a continuous vulcanizer was used, the vulcanization temperature Tv was lower than the deformation temperature Td of the hollow microspheres.
If the temperature is higher than (° C.) by 50 ° C. or more, deformation and crushing of the hollow microspheres due to high temperature and long-time heating may occur, making it impossible to produce a compressible layer for a printing blanket having a uniform porous structure. all right.

Further, from the results of Comparative Example 6, when the vulcanization temperature Tv was lower than the deformation temperature Td (° C.) of the hollow microspheres even when a continuous vulcanizer was used, foaming was insufficient, and the vulcanization was insufficient. It has been found that a compressible layer for a printing blanket having a porous structure having a porosity cannot be produced. On the other hand, from the results of each of the examples, the vulcanization was performed using a continuous vulcanizer or a hot press under the conditions of the vulcanization pressure Pv, the vulcanization temperature Tv and the vulcanization time within the ranges specified in the present invention. In each case, it was confirmed that a compressible layer for a printing blanket having a uniform porous structure, a uniform porous structure, a sufficient porosity, and a good porous structure could be produced.

When the results of the examples are compared, the vulcanization pressure P
It was confirmed that as v was smaller, the thickness and internal structure of the compressible layer became more uniform. << Printing Blanket >> Example 13 As a base cloth, a vulcanized adhesive obtained by mixing the following components and an appropriate amount of toluene was applied to the surface on the compressible layer side of the laminate prepared in Example 1 above. Were laminated.

[0082] Further, on the surface of the base fabric side of the laminate, the following components,
A rubber paste for a surface print layer mixed with an appropriate amount of toluene was applied and dried to form a layer of an unvulcanized rubber composition having a thickness of 0.50 mm.

[0083] Then, using a continuous vulcanizer equipped with the above-described laminate and having a structure shown in FIG. 1 and a belt 2 made of fiber reinforced rubber as a standard equipment, a vulcanization temperature Tv =
Each layer containing unvulcanized rubber was vulcanized by continuously heating under the conditions of 160 ° C., vulcanization time of 5 minutes and vulcanization pressure of 2 kgf / cm ² , to produce a printing blanket.

Example 14 A printing blanket was manufactured in the same manner as in Example 13 except that the laminate produced in Example 5 was used. Actual machine test The printing blankets of Examples 13 and 14 were mounted on a blanket cylinder of an offset rotary printing press and used continuously for two weeks for actual printing, and the thickness was measured. Little change from before.

By the way, in a conventional printing blanket provided with a compressible layer having a continuous pore structure formed by the above-described leaching method, such continuous use causes
In particular, it is known that the thickness of the butt of the mulberry increases to cause printing failure. This is considered to be because the cleaning liquid permeates the continuous pores to swell the rubber. From this, it was confirmed that both of the printing blankets of Examples 13 and 14 having the configuration of the present invention had better durability than the conventional ones.

[Brief description of the drawings]

FIG. 1 shows a continuous vulcanizing machine as an example of a vulcanizing apparatus provided with a member for heating and pressing in direct contact with an intermediate member, which is used when producing a compressible layer for a printing blanket of the present invention. FIG.

[Explanation of symbols]

 3 Intermediate members

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuji Yamazaki 514-3-810, Onoemachi, Kakogawa-shi, Hyogo (56) References JP-A-11-170724 (JP, A) JP-A-11-139028 ( JP, A) JP-A-6-1091 (JP, A) JP-A-5-309970 (JP, A) JP-A-3-244595 (JP, A) JP-A-2-20392 (JP, A) JP JP-A-61-27295 (JP, A) JP-A-61-27294 (JP, A) JP-A-58-114994 (JP, A) JP-A-58-114993 (JP, A) JP-A-56-93591 (JP, A) , A) JP-A-52-68509 (JP, A) JP-A-7-505341 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41N 10/00-10/04

Claims (10)

(57) [Claims] 1. A compressible layer for a printing blanket made of vulcanized rubber and having a porous structure, which is incorporated in a printing blanket, wherein the hollow layer has a shell of a thermoplastic resin in an unvulcanized matrix rubber. Using a vulcanizer equipped with a member for heating and pressing a sheet-shaped intermediate member including a layer of a rubber composition in which microspheres are dispersed by directly contacting the intermediate member, the following vulcanization pressure Pv [Kgf / c
m ² ] and the vulcanization temperature Tv (° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the atmospheric pressure without pressurizing the hollow microspheres. Is the deformation temperature (° C.) when heated. ] A compressible layer for a printing blanket, which is formed by vulcanizing the layer of the rubber composition by heating for 1 to 50 minutes. (1) A rubber composition is prepared by dispersing hollow microspheres having a shell of a thermoplastic resin in an unvulcanized matrix rubber. (2) At least one rubber composition is prepared. A sheet-like intermediate member is formed by laminating in layers on the base fabric of the layer, and (3) using a vulcanizing apparatus provided with a member for heating and pressing the intermediate member in direct contact with the intermediate member. And the following vulcanization pressure Pv [kgf / cm ² ] and vulcanization temperature Tv
(° C.), 0 <Pv ≦ 3.0 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the deformation temperature (° C.) when the hollow microspheres are heated at atmospheric pressure without pressing. ). ] A method for producing a compressible layer for printing blanket, comprising a step of vulcanizing the layer of the rubber composition by heating for 1 to 50 minutes. 3. A continuous vulcanizer comprising a heat roller rotating at a constant speed and a belt rotating in synchronization with the rotation of the heat roller while being pressed against the heat roller at a constant pressure. The method for producing a compressible layer for a printing blanket according to claim 2, wherein a vulcanizer is used. 4. A belt in the form of a felt is used as the belt for the continuous vulcanizer, and the intermediate member is formed by the following vulcanization pressure Pv [kgf / cm ² ] and vulcanization temperature Tv (° C.).
0 <Pv ≦ 0.2 kgf / cm ² Td ≦ Tv ≦ Td + 50 ° C. [where Td is the deformation temperature (° C.) when the hollow microspheres are heated at atmospheric pressure without pressing. . The method for producing a compressible layer for a printing blanket according to claim 3, wherein the rubber composition layer is vulcanized by heating for 1 to 50 minutes. 5. The method for producing a compressible layer for a printing blanket according to claim 4, wherein the vulcanization pressure Pv is 0.07 kgf / cm ² or less. 6. The method according to claim 2, wherein a hot press is used as the vulcanizing device. 7. The method for producing a compressible layer for a printing blanket according to claim 2, wherein the vulcanization temperature Tv (° C.) is in the range of Tv ≦ Td + 40 ° C. 8. The method according to claim 2, wherein the vulcanization temperature Tv (° C.) is in the range of Td + 10 ° C. ≦ Tv. 9. The method according to claim 2, wherein the vulcanization time is 3 to 40 minutes. 10. A printing blanket formed by vulcanizing the whole of the compressible layer for printing blanket according to claim 1 in a state of being laminated with another layer constituting the printing blanket.