JPH0149606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a soft vinyl chloride resin roll.

It is already known that vinyl chloride resin can be used as a material for printing materials.
120009, JP-A-54-2801 and JP-A-Sho
There is a publication No. 56-73240. However, the former two are related to gravure printing plates in which plastisol, etc. is applied onto a flat or cylindrical substrate surface by spraying, brushing, dipping, etc., then melted and the surface is polished. The vinyl resin is only thinly applied to the surface of the base, so it is hard to say that it is an original soft roll. In addition, although the latter method describes a method in which plastisol containing a high molecular weight plasticizer is blended with a paste range and is defoamed and then cast in a mold, air is drawn in by stirring during plastisol preparation, resulting in countless large and small bubbles. In order to remove the bubbles, it was necessary to leave the product still for a long period of time, and in order to completely remove even the smallest bubbles, it was necessary to provide a separate defoaming device such as a vacuum device. Furthermore, even if a defoaming device is installed, complete defoaming is not possible, and the residual bubbles expand or combine with each other due to heating after injection into the mold, forming large bubbles that appear in the soft roll.
When the surface of this roll was polished, the surface of the soft roll became uneven, making it impossible to put it to practical use. Moreover, the commercial value was also impaired in terms of appearance. This phenomenon was further enhanced when fillers were mixed into plastisol.

The inventors of the present invention have been intensively investigating a method for efficiently producing a soft vinyl chloride roll that does not contain air bubbles, and have found that by incorporating a small amount of antifoaming agent into plastisol, air bubbles can be easily removed from the sol, and vacuum Even without performing defoaming operations such as degassing, the manufactured soft vinyl chloride resin roll did not contain any air bubbles, and the air bubbles did not become an obstacle during the cutting and polishing process. Furthermore, it has been found that air bubbles can be more completely degassed and removed by applying vibration to the plastisol after it is injected into the mold and before it gels.

That is, an object of the present invention is to provide a method for efficiently producing a soft vinyl chloride resin roll that does not contain air bubbles. A method for producing a soft vinyl chloride resin roll, which comprises injecting a vinyl chloride plastisol into a mold, heating the plastisol to a temperature at which it gels, releasing the mold after cooling, and subjecting the surface to polishing.

The present invention will be explained in detail.

The polyvinyl chloride plastisol used in the method of the present invention contains a vinyl chloride paste resin, a plasticizer, and an antifoaming agent as essential components.

Vinyl chloride paste resin is prepared by adding vinyl chloride alone or a mixture of vinyl chloride and a comonomer copolymerizable with it, such as vinyl acetate, acrylic acid, methyl acrylate, ethylene, propylene, styrene, etc., using a conventional method. Preferably, they are produced by emulsion polymerization or by fine suspension polymerization. The comonomer copolymerizable with vinyl chloride is not limited to the above-mentioned specific examples, and the emulsifier or suspending agent used during polymerization is not particularly limited to the type. The paste resin may have a particle shape and properties that can be turned into a sol by adding a plasticizer. If necessary, a vinyl chloride mixing resin may be mixed with the paste resin for the purpose of lowering the viscosity. The amount of the mixing resin added is 50% of the total amount of the paste resin.
Used within a range of % by weight. (Hereinafter, it will be referred to as paste resin even if it is blended with a mixing resin.) The plasticizer used to prepare vinyl chloride plastisol (hereinafter referred to as plastisol) may be one that is used as a plasticizer for vinyl chloride resin. Various types can be used, and there are no particular limitations.
For example, dibutyl phthalate, diheptyl phthalate,
Phthalate ester plasticizers such as dioctyl phthalate (DOP), diisodecyl phthalate, butyl lauryl phthalate, ditridecyl phthalate, butyl benzyl phthalate, butyl phthalyl butyl glycolate, trimellitate ester plasticizers such as trioctyl trimellitate phosphate ester plasticizers such as tricresyl phosphate and trioctyl phosphate, tri-n-butyl citrate, dioctyl adipate,
Fatty acid ester plasticizers such as butyl benzyl adipate, dioctyl azelaate, dioctyl sebacate, methyl acetyl ricinoleate, etc. can be mentioned, and these may be used alone or in combination of two or more.

In addition to the above plasticizer, the present invention has a molecular weight of about 1000.
By using a polymer plasticizer of about 7,000 in combination, it is possible to prevent deterioration and improve the durability and other qualities of a soft vinyl chloride resin roll (hereinafter simply referred to as a vinyl chloride roll). If only a polymeric plasticizer is used, it is difficult to plasticize the paste resin, and the quality of the vinyl chloride roll is not significantly improved, and the properties of the vinyl chloride roll cannot be improved unless it is used in combination with a common plasticizer.
Examples of polymer plasticizers include polyester plasticizers and epoxy plasticizers, and specific examples include polypropylene adipate, polypropylene sebacate, epoxidized soybean oil, and Liquid nitrile rubber etc. are used. Also,
As a polymer plasticizer, a reactive plasticizer represented by diallyl adipate, diallyl maleate, dichloroallyl maleate, diallyl malonate, polyethylene glycol diacrylate, etc. can also be used in combination with a normal plasticizer.

Therefore, the amount of plasticizer used is in the range of 30 to 400 parts by weight, preferably 50 to 250 parts, particularly 50 to 200 parts by weight, based on 100 parts by weight of the vinyl chloride paste resin. If the amount of plasticizer added is less than 30 parts by weight, it will be difficult to form a sufficient liquid fluid at room temperature, causing problems during injection into a mold, making defoaming especially difficult, and making air bubbles more likely to form inside the PVC roll. On the other hand, if more than 400 parts by weight is used, defoaming becomes easier, but the PVC roll as a product is too soft.
It becomes difficult to use it for normal purposes.

The antifoaming agent, which is an essential component of the present invention, is not particularly limited as long as it has an antifoaming or defoaming effect on plastisol. Defoaming and defoaming are those that have the effect of not creating air bubbles when the paste resin is mixed with a plasticizer, or a filler that will be added as necessary, as described below, or that can easily defoam even if air bubbles are formed. refers to something that has the effect of
Air bubbles may be removed before the plastisol gels. Antifoaming agents include silicone emulsion, silicone oil, polyglycol compounds,
polyether compounds, anionic surfactants,
Nonionic surfactants are used, and the amount is 0.1 to 8% by weight based on vinyl chloride plastisol.
Preferably 1 to 5% by weight is most effective. Addition of 8% by weight or more will not further promote the antifoaming effect, and depending on the type of antifoaming agent, if it exceeds 8% by weight, it may ooze out to the surface when the plastisol gels, or the PVC roller may This will impede its functions.

In addition to the above-mentioned essential components, the plastisol used in the method of the present invention may contain, for example, a diluent,
UV absorbers, colorants, heat stabilizers, antioxidants,
Of course, additives (materials) used in ordinary plastisols, such as fillers, can be added as appropriate. Fillers include talc, calcium carbonate, silica,
Examples include glass powder, glass bulbs, glass fibers, natural fibers, synthetic fibers, carbon fibers, metal fibers, etc., and it is preferable to use them in an amount of 10 to 50 parts by weight per 100 parts by weight of plastisol.

In the method of the present invention, it is convenient to use, for example, the casting mold shown in the drawings, since air bubbles can be removed with high efficiency.

The drawing is a perspective view of a casting mold. In the figure, 1
Reference numerals denote a casting mold, 2 and 2' the side end surfaces of the mold, 3 a roll shaft receiving hole, and 4 and 4' a shaft core holding plate, respectively. The mold 1 has a rectangular opening at the top and has both end surfaces 2 and 2'.
Each of the rollers 2' is provided with a roll shaft receiving hole 3 for supporting the metal shaft of the PVC roll. The receiving hole 3 is provided slightly below the center of both end faces,
It is desirable that at least a portion of the inner wall of the mold 1 below the receiving hole 3 forms an arc at approximately equal intervals with respect to the axis, preferably at equal intervals. and receiving hole 3
The upper part is box-shaped with an upwardly extending peripheral wall. Receiving hole 3
The upper peripheral wall is not limited to a box shape, but may form an elliptical arc with respect to the axis. Of course, the mold 1 may have legs or hakama to stabilize it. Further, it is preferable that the receiving hole 3 is usually cut from the upper part of the side end surfaces 2, 2' so that the roll axis is placed at the lowest position. The shaft holding plates 4, 4' having an H-shaped rear cross section on which the shaft core is placed are capable of vertically sliding the cut side end surfaces 2, 2' to close the openings of the side end surfaces. ing.

To manufacture a PVC roll by the method of the present invention, first, the roll shaft is placed in the shaft receiving hole 3 of the mold 1, and the side end surface of the mold 1 is closed with the shaft holding plates 4, 4'. Then, the plastisol described above is injected and filled into the mold 1. Since the plastisol is quickly injected into the mold, air bubbles are generated due to the entrainment of air, but the air bubbles gather at the upper opening of the mold in a very short time and are easily degassed. The mold containing the plastisol is heated until the plastisol gels. In the method of the present invention, by applying vibration when the plastisol is injected into the mold or during heating, the rate of degassing can be significantly increased in combination with the action of the antifoaming agent. The vibration may be applied using ultrasonic waves or the like, and the method and means thereof are not particularly limited, and the simplest vibrator method may be used. For example, amplitude 10~
30 mm, 5 to 10 minutes at a cycle of 60 to 120 times/minute is sufficient. However, it is preferable that the vibration be applied at a temperature of 120° C., taking into consideration the gelation temperature, distortion due to vibration, etc. Gelation of plastisol is carried out at 130-300℃, preferably at 160℃
It is best carried out at a temperature range of ~250°C, especially 180-230°C.

The molten gel in the mold into which the core is inserted is gradually cooled to remove cooling distortion. Bubbles generated during heating and gelation of plastisol rise above the mold, collect on the opening surface of the mold, and a small number of them solidify as bubbles. Next, the cooled and solidified elastic gelled product is released from the mold and then cut into the shape of a vinyl chloride roll using a mechanical method, such as a cutting tool, and the surface is polished to produce a product. Bubbles that had gathered on the mold opening surface were completely removed during cutting, and the PVC roll contained no air bubbles at all.
Therefore, surface polishing does not create unevenness on the surface of the vinyl chloride roll, and a smooth surface can be achieved.

When gelling occurs in a mold that has the shape of the roll itself, that is, the upper part of the shaft core receiving hole 3 forms an arc at equal intervals with respect to the shaft core, the upper half of the mold Since air bubbles adhere to the surface of the roll and the air bubbles cannot be completely defoamed, the resulting PVC roll solidifies with air bubbles entrapped on its upper half surface. The surface of this vinyl chloride roll is already uneven when it is released from the mold, and when the surface is polished, the surface becomes pocked and its commercial value is lost.

The vinyl chloride roll obtained by the method of the present invention is
Like conventional rubber rolls, it is used as a roll for letterpress printing, offset printing, flexo printing, etc., and as a dewatering roll.

According to the method of the present invention, air bubbles are quickly removed from the plastisol in the mold, and by applying vibration, the degree of air removal can be further improved. By using a mold with a wide open upper part, the air bubbles generated during heating and gelation can be collected on the open surface of the gelled product, and by cutting and polishing this, it is possible to create a mold that does not contain air bubbles. A soft vinyl chloride resin roll with a smooth surface is produced. Furthermore, since the plastisol can be easily degassed, there is no need to leave the plastisol still for a long time, which greatly contributes to improving productivity.

The method of the present invention will be explained in detail below with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example: Polyvinyl chloride paste resin with a degree of polymerization of approximately 2000
100 parts by weight, 250 parts by weight of plasticizer, and 5 parts by weight of heat stabilizer.
Parts by weight were mixed to prepare plastisol with a viscosity of 25,000 cp at 25°C. Silicone oil was added as an antifoaming agent in an amount corresponding to 2% by weight, and the mixture was stirred uniformly.

The plastisol obtained in this way was injected into the mold shown in the drawing with the shaft core placed in the receiving hole, and transverse vibration was applied for 5 minutes while the temperature was raised to 50℃, and then the plastisol was heated to 200℃.
The mixture was heated to a temperature of 100 mL to form a gel. The gelled product was slowly made and cooled to room temperature to solidify, and then, after being released from the mold, it was cut and polished with a cutting tool to produce a vinyl chloride roll with a smooth surface. The vinyl chloride roll contained no air bubbles.

For comparison, a vinyl chloride roll was produced in the same manner as in the example except that no antifoaming agent was added. This vinyl chloride roll contained many large and small air bubbles, and some holes were also formed on the roll surface.

[Brief explanation of drawings]

The drawing is a perspective view of an example of a mold used for manufacturing the roll of the present invention.

Claims (1)

[Claims] 1. A polyvinyl chloride plastisol containing 0.1 to 8% by weight of an antifoaming agent is injected into a mold, heated to a temperature at which the plastisol gels, and after cooling, the mold is released and the surface is polished. A method for manufacturing a soft vinyl chloride resin roll characterized by rubbing. 2. The method for producing a soft vinyl chloride resin roll according to claim 1, wherein vibration is applied until the temperature of plastisol reaches 120°C. 3. Claim 1, wherein the mold has roll shaft receiving holes on both end faces, and the inner surface of at least a portion below the receiving holes is formed into an arc at approximately equal intervals with respect to the roll shaft. The method for producing a soft vinyl chloride resin roll according to item 1 or 2.