JPH08155971A - Continuous heat treatment apparatus - Google Patents

Abstract

PURPOSE: To suppress the protrusion (flash and vent spew) of rubber at the time of the vulcanization of a radial tire by providing a surface temp. control means for an article to be treated and an interlock control means of a heat source and feed to a heat treatment chamber of the article to be treated. CONSTITUTION: A halogen heater 4 irradiates an unvulcanized green tread material sheet A with infrared rays by a heating means consisting of a reflecting mirror 3 and an infrared pervious plate 5. Next, the treated layer 9 of the sheet A is monitored by an infrared thermometer 7 to be fed back to regulate the input power of the halogen heater 4 and the surface temp. of the sheet A is controlled to 100-600 deg.C. The whole is surrounded by a cover 1 to constitute a heat treatment chamber B and nitrogen gas is blown into the chamber B from a gas send-in port 2 to be discharged from an exhaust port 6. Only the surface layer of about 100μm of the sheet A is vulcanized and the interior thereof is held to an unvulcanized green tread state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for continuously heat-treating a long material such as a rubber sheet or a resin film, and more particularly to an apparatus for crosslinking only the surface by heat treatment. For example,
Only the surface of the tread member before vulcanization in order to prevent rubber protrusion (burrs, flashes, spews, etc.) that occurs during molding vulcanization when manufacturing rubber tires, and to reduce mold fouling The present invention relates to a continuous surface heat treatment apparatus for pre-vulcanizing.

[0002]

2. Description of the Related Art A tire manufacturing method is to vulcanize a raw tire before vulcanization (raw tire) that is rawly made into a tire shape by cutting, stacking or joining various rubber kneaded materials. It is mounted on a machine, inflated with a bladder or the like, and subjected to so-called vulcanization in which it is treated under high internal pressure and high temperature for a certain time. At this time, if the air between the raw tire and the tire mold is not discharged to the outside, a bare surface occurs on the tire surface, resulting in a defective product. Especially, the occurrence is remarkable especially in high-performance tires having complicated irregularities which have increased in recent years. Therefore, the air is generally discharged to the outside by the following method. a. Provide a vent hole that communicates with the outside of the mold. b. Sectional type split mold or small segment However, a. Of course, b. In this case as well, a thin rubber sticking out occurs between the molds, and a work for trimming this is performed. Particularly, the protrusion such as flash which is difficult to be trimmed becomes a problem as a work requiring more man-hours. On the other hand, the conventional vulcanization method using a mold has a problem that the mold is easily contaminated and cleaning thereof requires a lot of labor and cost.

As a means for suppressing the protrusion of the rubber, one of the purposes has been proposed to make the above-mentioned sectional type split mold or the tread pattern portion small segment, but it is not always perfect, and a minute flash does not occur. Further, it is difficult to trim, and the man-hours are required more than ever before. In addition, as a means to prevent this protrusion,
The following types of rubber that are difficult to flow can be considered, but each has its own problems. a. Hardening by increasing the filling amount of carbon black, etc .: It is difficult to knead, and it is extremely difficult to put into practical use considering the compounding amount that is considered from the required performance of the tire. b. Method of accelerating vulcanization speed: Since the protrusion of rubber is the flow of rubber at the start of vulcanization, the amount of sulfur and the type of vulcanization accelerator are selected in order to accelerate the vulcanization speed of the rubber material in contact with the mold. However, it is extremely difficult to put into practical use because the effect cannot be obtained as expected and the so-called burn phenomenon easily occurs during kneading, extrusion or rolling. c. Use of a curing agent for rubber: It is possible to use a curing agent as a compound to harden unvulcanized rubber and prevent it from losing its shape. However, because of the occurrence of curing during kneading and subsequent processing steps, tire performance Therefore, it is extremely difficult to put it into practical use. d. Surface application of cross-linking agent: The rubber surface can be cured by applying a cross-linking agent to the surface before vulcanization, but there are problems that the number of steps is increased and the material cost is high. e. Use of electron irradiation as a pre-vulcanization means: Use of carbon-carbon bond reaction between rubber molecules by electron irradiation as one of pre-vulcanization means as one of means for suppressing the occurrence of vent spew and flash However, for example, Japanese Patent Publication Sho 5
6-11605. However, although the electron irradiation treatment is very effective in suppressing the protrusion of rubber such as spews and flashes, in addition to safety problems such as expensive equipment and difficulty in preventing X-rays, However, there is a problem that the rubber performance is deteriorated by electron irradiation rays (especially, the abrasion resistance is reduced by 5 to 10%), and it is possible to put it into practical use, but it requires a large space. On the other hand, polymer films and the like may have problems such as distortion and deformation after extrusion processing, and it may be necessary to take countermeasures and prevent them. A simple processing device that suppresses strain relaxation or deformation of the film is desired.

[0004]

SUMMARY OF THE INVENTION In view of these problems of the prior art, an object of the present invention is (a. Between sectional molds, b. Small tread portion) during vulcanization of radial tires and the like. To prevent rubber squeeze out (flash and vent spew) that occurs in segmental molds, c. Micro vent holes, etc., and to pre-press only the surface of the tread member before vulcanization to further reduce mold contamination. Providing a continuous surface heat treatment apparatus for sulfurization,
It is an object of the present invention to provide a continuous surface heat treatment apparatus which relaxes strain of a polymer film and suppresses deformation.

[0005]

As a result of repeated studies to solve the above problems, the present inventor radiates infrared rays from an unvulcanized rubber sheet after extruding a rubber-blended kneaded dough, raw-fabrication, etc. Found a method of crosslinking only the outer surface of the unvulcanized rubber sheet by passing a specific heating means to
An apparatus for continuously performing the heat treatment has been completed.

The apparatus of the present invention comprises the following constitutions (1) to (6): (1) A heating means equipped with a heat source for radiating infrared rays and an infrared transmitting plate for uniformly dispersing and transmitting the infrared rays; Continuous heat treatment of the surface of the object to be processed, in which a surface temperature control means of the object to be processed and an interlock control means of the heat source and the transportation are provided in the object heat treatment chamber consisting of a constant speed transportation means of the object to be treated and a heat retaining means. apparatus. (2) Heating means having a heat source temperature of 500 ° C. to 6000 ° C., a constant-speed conveying means for conveying an object to be treated consisting of an unvulcanized rubber compounded sheet by a roller conveyor and passing the heating means for 90 seconds or less, Surface temperature of vulcanized rubber compounded sheet is 1
Unvulcanized rubber compounding consisting of surface temperature control means having output and focus control function of light source or heat source configured by surface temperature monitor so as to be 00 ° C to 600 ° C, and interlock control means capable of turning off heat source at the same time when transportation is stopped The continuous surface heat treatment apparatus according to claim 1, which vulcanizes only the surface of the sheet. (3) The outer surface temperature of the unvulcanized rubber compounded sheet is 200 ° C to
Item 3. The surface continuous heat treatment apparatus according to Item 2, wherein the unvulcanized rubber compounded sheet has a heating means passing time of less than 20 seconds at 400 ° C. (4) The outer surface temperature of the unvulcanized rubber compounded sheet is 250 to 3
3. The continuous surface heat treatment apparatus according to claim 2, wherein the unvulcanized rubber-blended sheet has a heating means passage time of less than 3 seconds at 50 ° C. (5) The continuous surface heat treatment apparatus according to any one of claims 1 and 2, wherein a reflection mirror is provided on a heat source that radiates infrared rays. (6) The continuous surface heat treatment apparatus according to claim 1 or 2, wherein a gas inlet is provided on one side of the heat treatment chamber and an exhaust port is provided on the other side.

The surface continuous heat treatment apparatus of the present invention is an apparatus for causing a crosslinking reaction only on the surface of a sheet material such as a tire tread member before vulcanization. The heating means of the apparatus of the present invention comprises a heat source for emitting infrared rays and an infrared transmitting plate for uniformly dispersing and transmitting the infrared rays. A general-purpose heater such as a lamp heater or a ceramic heater may be used as the heat source. For example, a heater that is turned off instantly when the conveyance of the object to be processed is stopped is preferable. The heat source may be pulsed on / off as required. Further, it is preferable that a mirror of gold plating, silver plating, aluminum plating or the like is arranged on the back surface of the heat source to effectively supply the heat energy generated by the heat source to the object to be processed. The infrared ray transmitting plate is a window that covers the heat source, and it is preferable that the material of the infrared ray transmitting plate is a material such as quartz glass that transmits infrared rays well, which improves the temperature distribution (uniformity) in the heat treatment chamber and prevents the heat source from being contaminated. The heat source temperature is preferably 500 ° C to 6000 ° C.

The conveying means relating to the apparatus of the present invention, the sheet-like or plate-like article which is the object to be treated extruded from the extruder is usually sent directly to the roller conveyor for conveyance. Usually, the transport speed is selected according to the type of the object to be processed, the required performance, the output of the heater and the length of the heater zone.
cm / min to 400 m / min, especially 1 m / min
100 m / min is preferably used. The time for passing through the heating means is preferably 90 seconds or less. The surface temperature of the object to be treated is more preferably 200 to 400 ° C. and 20 seconds or less. The object heat treatment chamber according to the apparatus of the present invention can be provided by covering the heat treatment means, the sheet material as the object to be treated, and the entire roller conveyor so as to be separated from the outside. No need to make. This processing chamber is necessary to keep the surface temperature of the object to be processed constant and to efficiently exhaust the gas generated by the crosslinking reaction due to the heating of the object to be processed.

It is preferable to provide a gas inlet port on one side of the object heat treatment chamber and an exhaust port on the other side of the apparatus according to the present invention. Although air can be used as the feed gas, when the temperature rises, the surface of the object to be treated may be deteriorated due to oxidation, etc. In the case of the above treatment, etc., an inert gas such as Ar, He, Xe, nitrogen, etc. may be used if necessary. On the contrary, when it is desired to accelerate the oxidation reaction of the object to be treated, oxygen or ozone may be used, but in this case, safety precautions are required. The introduction of gas in the apparatus of the present invention not only makes the temperature distribution in the processing chamber uniform, but also has the effect of removing contaminants generated from organic substances such as rubber.

The surface temperature control means relating to the apparatus of the present invention uses an infrared thermometer, a thermocouple or the like as a thermometer,
The surface temperature of the object is monitored at several points. The information of this temperature measurement is fed back to the input power of the heat source, the flow rate of the incoming gas, etc. and processed with good controllability. The surface temperature is usually 100 to 600 ° C, preferably 200 to 40
0 ° C.

In the interlock control means according to the apparatus of the present invention, the power of the heater is turned off in conjunction with the electric signal for the stop, for safety when the conveyance is stopped.

The unvulcanized rubber compounded sheet according to the present invention is an extruded kneading material after kneading work in which a predetermined compounding agent and a filler are uniformly dispersed in a raw rubber using various kneading machines. It is a rubber compounding sheet that has not been vulcanized after being subjected to processing such as calendar processing and green making. For example,
It is a rubber product member before vulcanization of a raw dough flat plate obtained by extruding a kneaded dough.

When vulcanizing the outer surface of the unvulcanized rubber-blended sheet by heating the outer surface of the unvulcanized rubber compounded sheet by the apparatus of the present invention, a halogen heater, which normally uses a halogen lamp as a heat source, a ceramic heater as an infrared heater, A heat source that emits infrared rays or far infrared rays, such as a nichrome wire heater, is placed at a distance of 0.1 to the outer surface of the unvulcanized rubber compounding sheet.
Set to 100 cm and heat. Normally, the heat source temperature is 5
The temperature of the outer surface of the unvulcanized rubber compounded sheet is 100 to 600 ° C., and the irradiation time is 0.05 to 90 ° C.
Process in seconds. The focus or input of the heat source is adjusted so that the irradiation time is preferably 0.1 to 30 seconds at 200 to 400 ° C. When the surface temperature is less than 100 ° C. and the irradiation time is 90 seconds, only the outer surface cannot be vulcanized. When the temperature is 600 ° C. or higher, the irradiation time needs to be remarkably shortened, which makes it difficult to control the surface temperature. Especially in the case of tire tread raw material,
A surface temperature of 250 ° C. to 350 ° C. and a treatment time of less than 3 seconds are desirable. Treatment at 300 ° C. for 3 seconds or more may cause foaming and deteriorate the appearance. When the outer surface of the unvulcanized rubber compounded sheet is vulcanized by the device of the present invention, the thickness of the outer surface is 1.
Only 0 mm or less can be vulcanized. Thickness 1.0m
Crosslinking (vulcanization) of the outer surface exceeding m is not so preferable that the required shape is obtained at the time of vulcanization because the surface is significantly hardened. Moreover, there is a possibility that so-called bear may occur.

The rubber compounding composition of the unvulcanized rubber compounding sheet according to the method of the present invention is not particularly limited. There are various compositions depending on the shape and application of the desired rubber product, but synthetic rubber, natural rubber, carbon black, zinc white, stearic acid, antioxidant, vulcanization accelerator, sulfur, aroma oil, spindle oil, etc. It consists of softening agents. Particularly in the case of blending tread tires, for example, the raw material rubber is SBR1.
85 parts by weight of carbon black, 20 parts by weight of oil, 3 parts by weight of ZnO, 1.5 parts by weight of sulfur, 1.2 parts by weight of vulcanization accelerator, and 1.0 part by weight of antioxidant with respect to 00 parts by weight. The composition of the ratio is shown.

The unvulcanized rubber compounded sheet whose surface is heat-treated (prevulcanized) only on the outer surface by the device of the present invention is a rubber product inside the unvulcanized rubber compounded sheet at the start of vulcanization. Since the flow of the outer surface is suppressed rather than the flow of the rubber, the protrusion of the rubber such as flasher and Benspew after the vulcanization is significantly suppressed.

[0016]

EXAMPLES The present invention will be described below with reference to examples. The compounding compositions of the rubber kneaded doughs used in Examples and Comparative Examples are as follows. Rubber kneaded material compounded for tire tread: SBR 100 parts by weight carbon black 85 parts by weight Process oil 20 parts by weight Zinc white 3 parts by weight Sulfur 1.5 parts by weight Vulcanization accelerator 1.2 parts by weight Anti-aging agent 1.0 Parts by weight

Example 1 Only the surface of an unvulcanized rubber compounding sheet was vulcanized using the surface heat treatment apparatus shown in FIG. This will be described with reference to the drawings. An unvulcanized raw tread material (width 300 mm 3, thickness 10 mm) A obtained by extruding a rubber kneaded material mixed for a tire tread is conveyed on a roller conveyor 8 at a speed of 30 m / min. This sheet was irradiated with infrared rays by a heating means (heater zone: width 0.35 m, length 1 m) consisting of a halogen heater 4, a reflection mirror 3 and an infrared ray transmitting plate 5 (irradiation time is 2 seconds). By installing five infrared thermometers 7 and monitoring and feeding back the treatment layer 9 of the sheet, the input power of the halogen heater 4 was adjusted to control the surface temperature of the sheet to 300 ° C. The whole is surrounded by a cover 1 to form a heat treatment chamber B and a gas inlet 2
[(Details are shown in FIG. 3 (a)].
It was blown in with n and discharged from the exhaust port 6. Only about 100 μm of the surface layer of the raw tread material was vulcanized and the inside remained as unvulcanized raw tread. As described above, the surface heat treatment apparatus of the present invention can be easily incorporated into a conventionally used line.

Example 2 The surface heat treatment of a polyester film was carried out using the surface heat treatment apparatus shown in FIG. This will be described with reference to the drawings. Polyester sheet A '(width 300m
m, thickness 100 μ) at a speed of 30 m / min on the roller conveyor 8. Two infrared irradiators consisting of a heater 4, a mirror 3 and an infrared transmitting plate 5 are installed above and below this sheet A ′, and five infrared thermometers 7 are installed above and below the sheet, and a treatment layer 9 is provided on the front and back of the sheet. Was monitored and the input power of the halogen heater 4 was adjusted to control the surface temperature of the sheet at 290 ° C. The whole of these was surrounded by a cover 1 to form a heat treatment chamber B, and air was blown at 10 liters / min from a gas inlet 2 [(details in FIG. 3 (a)] and discharged from an exhaust port 6.

[0019]

EFFECTS OF THE INVENTION When the surface of the unvulcanized rubber compounded sheet is vulcanized by the apparatus of the present invention, rubbers such as burrs, flashes, spews, etc., at the time of mold vulcanization of rubber products such as radial tires and anti-vibration rubbers. The protrusion of the mold is suppressed, and the dirt of the mold is remarkably reduced. In addition, the rubber products have less deterioration in breaking strength, breaking elongation, etc. compared to the conventional electron beam processing methods, and the processing device can be easily manufactured and it is compact, so it can be attached to existing manufacturing lines. It has the advantages that it is easy and does not require expensive equipment such as the conventional method for treating electron irradiation rays, and that it does not require equipment such as X-ray protection and has good safety.

[Brief description of drawings]

FIG. 1 is a schematic view of a surface heat treatment apparatus (single-sided treatment).

FIG. 2 is a schematic view of a surface heat treatment apparatus (double-sided processing).

3A and 3B are diagrams showing examples of a gas outlet of a surface heat treatment apparatus.

[Brief description of reference numerals]

 A, rubber compounding sheet B, heat treatment chamber A ', polyester sheet 4, heater 5, infrared ray transmitting plate 7, thermometer 8, roller conveyor 11, wind direction plate

Claims (6)

[Claims] 1. A continuous heat treatment apparatus for continuously heating and cross-linking the outer surface of an unvulcanized rubber compounded sheet, comprising a heat source for radiating infrared rays and an infrared transmitting plate for dispersing and transmitting infrared rays, and a heat treatment. The surface temperature control means of the object to be processed in the object heat treatment chamber consisting of the conveying means capable of controlling the object conveying speed and the heat retaining means,
And a surface continuous heat treatment apparatus for an object to be processed, which is provided with an interlock control means for heat source and transportation. 2. A heating means having a heat source temperature of 500 ° C. to 6000 ° C., an object to be treated composed of an unvulcanized rubber compounding sheet is conveyed by a roller conveyer and a time for passing between the heating means is 9
Surface temperature control having a function of adjusting the output of a light source or a heat source configured by a surface temperature monitor such that the surface temperature of the unvulcanized rubber-containing sheet is 100 ° C. to 600 ° C. 2. The surface continuous heat treatment apparatus according to claim 1, wherein only the surface of the unvulcanized rubber compounding sheet, which comprises an interlock control means for cutting off the heat source at the same time as stopping the transportation, is vulcanized. 3. The outer surface temperature of the unvulcanized rubber compounded sheet is 2
The continuous surface heat treatment apparatus according to claim 2, wherein the unvulcanized rubber-blended sheet has a heating means passage time of less than 20 seconds at 00 to 400 ° C. 4. The outer surface temperature of the unvulcanized rubber compounded sheet is 2
The continuous surface heat treatment apparatus according to claim 2, wherein the unvulcanized rubber-blended sheet has a heating means passage time of less than 3 seconds at 50 to 350 ° C. 5. The surface continuous heat treatment apparatus according to claim 1, wherein the heat source for emitting infrared rays is provided with a reflecting mirror. 6. The surface continuous heat treatment apparatus according to claim 1, wherein a gas inlet is provided on one side of the object heat treatment chamber and an exhaust port is provided on the other side.