JP5192136B2 - Process oil for rubber - Google Patents

Description

  The present invention relates to a process oil for rubber that is applied to natural rubber and synthetic rubber to form a rubber composition.

  In order to improve the mechanical properties and processability of rubber materials, rubber process oils are generally blended with rubber materials used in tire manufacture. In addition to rubber materials such as natural rubber and synthetic rubber, this process oil for rubber is used as a lubricating oil and solvent component used in thermoplastic resin plasticizers and constituents of printing inks, recycled asphalt softeners, etc. ing.

  As the process oil for rubber, an extract having a large amount of aroma generated as a by-product when producing a lubricating base oil by solvent refining of a debris oil obtained by removing a vacuum distillation residue of paraffinic crude oil has been used. However, in recent years, aroma oils for tires that are not carcinogenic are produced by various production methods due to carcinogenic problems.

  In the production of rubber for tires, the compatibility between rubber process oil and rubber, which is related to the quality of rubber properties, is important, so the aroma content in rubber process oil is an important factor. Excessive content also increases the carcinogenicity of rubber process oils, so the aroma that causes carcinogenicity is removed while maintaining compatibility between rubber process oil and rubber in good condition. There was a need to do.

  Furthermore, in recent years, the harmfulness of polycyclic aromatic hydrocarbons (PCA: POLYCYCLIC AROMATICS, PAH (POLYAROMATIC HYDROCARBON), the same shall apply hereinafter) in rubber process oils has become a problem. The process oil for rubber is required to reduce the PCA in the process oil for rubber in order to pollute the environment as tire dust, and in Europe, etc., the mineral oil with 3% by weight or more of PCA is restricted in handling. receive. On the other hand, the high aromatic content extracted oil obtained by the conventional production method contains a large amount of polycyclic aromatic hydrocarbons, reducing PCA (specifically, less than 3% by mass). ) There is an urgent need to develop process oils for rubber and methods for producing the same.

  Against this background, technologies relating to rubber process oils that reduce PCA and achieve both compatibility with rubber and non-carcinogenicity have been studied. For example, tire rubbers using a combination of naphthenic asphaltenes and solvent-extracted oils. A technique related to a method for producing a process oil for rubber is disclosed (for example, Patent Document 1). Moreover, the technique regarding the manufacturing method of the process oil for rubber | gum by carrying out the solvent extraction of the 2nd step from the extraction residue oil which carried out solvent extraction is disclosed (for example, patent document 2). In addition, as another means, a technique relating to a method for producing a rubber-rubber process oil using an extract obtained by solvent extraction of debris oil is also disclosed (for example, Patent Document 3 and Patent Document 4).

Japanese Patent Laid-Open No. 11-80434 Japanese Patent Laid-Open No. 11-80751 JP 2000-80208 A JP 2002-3861 A

However, although the process oil for rubber obtained by the technique disclosed in Patent Document 1 described above can be said to be considered to be safe, the rubber composition using this process oil for rubber is a conventional aroma oil. It was not possible to show the same performance as the rubber composition using. Further, the process oil for rubber obtained by the technique disclosed in Patent Document 2 described above cannot be said to have sufficient effects for reducing rubber physical properties and carcinogenic substances. Furthermore, the process oil for rubber obtained by the techniques disclosed in Patent Document 3 and Patent Document 4 described above has a high pour point due to the use of paraffinic residual oil as it is. The rubber composition using the process oil for rubber was not preferable because wax precipitated on the rubber surface.
In addition, the technique disclosed in the above-mentioned patent document sets the extraction conditions for solvent extraction that satisfies the properties of rubber process oil such as PCA, so that a by-product extraction residual oil, that is, a conventional process for producing a lubricating base oil It was necessary to change the solvent extraction conditions in the production process, resulting in problems in the production of lubricating base oils other than rubber process oils.

  Under these circumstances, the present invention provides rubber process oils that can exhibit the same properties as conventional aroma oils in rubber properties, are free from carcinogenic problems, and are excellent in safety. Providing rubber process oils that can be manufactured without changing the manufacturing process of the lubricant base oil produced as a by-product, have good rubber properties, have no carcinogenic problems, and have excellent safety. There is to do.

As a result of intensive studies to achieve the above object, the present inventors have obtained a base material obtained by performing a specific treatment on a specific raw material, or a specific treatment on a specific raw material. It has been discovered that the object can be achieved by blending a base material and a specific lubricating base oil. The present invention has been completed based on such findings.
That is, the present invention
(1) A raffinate and an extract obtained by performing a first solvent extraction using a defragmented oil obtained by removing a vacuum distillation residue oil obtained from paraffinic crude oil having a 1% by volume distillation temperature of 380 ° C. or higher. And then
(A1) An extract obtained by further subjecting the raffinate to a second solvent extraction and / or (A2) An extract obtained by the first solvent extraction being obtained by further subjecting the raffinate to a second solvent extraction. Raffinate,
A rubber process oil comprising the following properties (a) to ( d ):
(A) Benzo (a) pyrene 1 mass ppm or less (b) Content of specific aromatic compound 10 mass ppm or less (c) Polycyclic aromatic hydrocarbon (PCA) content Less than 3 mass%
(D) Aromatic content (% C _A ) 15-35
(2) The first solvent extraction and the second solvent extraction are both performed using N-methylpyrrolidone or furfural as a solvent under the conditions of a solvent ratio of 1.0 to 2.0 and an extraction temperature of 80 to 120 ° C. Process oil for rubber as described in (1) above,
(3) The process oil for rubber according to (1) or (2), further comprising (B) a lubricating base oil having a polycyclic aromatic hydrocarbon (PCA) content of less than 3% by mass,
(4) The lubricant base oil of (B) is 1 mass ppm or less of benzo (a) pyrene, the content of a specific aromatic compound is 10 mass ppm or less, the kinematic viscosity (100 ° C.) 5 to 40 mm ² / s, the flash point. The blending ratio of the process oil for rubber according to (3) above, which is 200 ° C. or higher, and the lubricating base oil of (5) (B) is 5 to 50% by volume based on the total amount of process oil for rubber (3) or process oil for rubber according to (4),
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the process oil for rubber | gum which has the characteristic equivalent to the conventional aroma oil in a rubber | gum physical property, is free from a carcinogenic problem, and was excellent also in safety can be provided. In addition, according to the present invention, a rubber process that can be produced without changing the production process of the by-produced lubricating base oil, gives good rubber properties, has no carcinogenic problems, and has excellent safety. Oil can be provided.

  The first process oil for rubber of the present invention is made from a defragmented oil obtained by removing a vacuum distillation residue oil obtained from paraffinic crude oil having a 1% by volume distillation temperature of 380 ° C. or more as a raw material. To obtain a raffinate and an extract, and then (A1) an extract obtained by further subjecting the raffinate to a second solvent extraction, and / or (A2) an extract obtained by the first solvent extraction. Is a process oil for rubber made of raffinate obtained by further performing a second solvent extraction (hereinafter, this process oil for rubber may be referred to as “rubber process oil (A)”).

The degreased oil used as a raw material for the process oil for rubber (A) of the present invention is obtained by subjecting a paraffinic crude oil to atmospheric distillation, vacuum distillation, and degrease. In this case, each of the atmospheric distillation, the vacuum distillation, and the deflaking condition may be a normal condition and is not particularly limited.
However, the vacuum distillation conditions need to be controlled so that the 1% by volume distillation temperature (T ₁ ) in the distillation properties of the vacuum distillation residue oil is 380 ° C. or higher, preferably 385 ° C. or higher. When degassed oil using vacuum distillation residue oil with T ₁ of less than 380 ° C. is used as a raw material, the content of benzo (a) pyrene, benzo (e) pyrene, etc. in rubber process oil (A) increases. In some cases, it is difficult to obtain a process oil for rubber that is not carcinogenic and has high safety.

The process oil for rubber of the present invention comprises the extract from (A1) and / or the raffinate (A2) obtained by using the above-mentioned desiccated oil as a raw material, performing the first solvent extraction and the second solvent extraction. The process oil for rubber (A) of the present invention is obtained.
The extraction conditions for the first solvent extraction and the second solvent extraction are not particularly limited and can be selected from a wide range. For example, the extraction conditions for the first solvent extraction are set according to the normal (conventional) manufacturing conditions of the lubricating base oil, the extraction conditions for the second solvent extraction are set as appropriate, and the rubber has the desired properties. The method of obtaining process oil is mentioned. In the production of the raffinate obtained by the first solvent extraction by such a method, that is, the process oil for rubber according to the present invention, the extraction conditions in the production process of the normal lubricating base oil produced as a by-product should be changed. It is possible to obtain the process oil for rubber of the present invention.
More specifically, the first solvent extraction and the second solvent extraction (second solvent extraction of (A1) and (A2)) both use N-methylpyrrolidone or furfural as the solvent, and the solvent ratio A method performed under extraction conditions of 1.0 to 2.0 and an extraction temperature of 80 to 120 ° C. is preferable.

  In the rubber process oil (A) in the present invention, the mixing ratio of the extract (A1) and the raffinate (A2) obtained by the first solvent extraction and the second solvent extraction is not particularly limited. Any of A1) alone, (A2) alone, and a mixture of (A1) and (A2) at an arbitrary ratio can be used.

The process oil for rubber (A) of the present invention must satisfy the following properties (a) to (c). This is because there is no carcinogenic problem and safety is ensured.
(A) Benzo (a) pyrene 1 mass ppm or less (b) Content of specific aromatic compound 10 mass ppm or less (c) Polycyclic aromatic hydrocarbon (PCA) content less than 3 mass% These will be described below To do.

(A) Content of benzo (a) pyrene:
In the process oil for rubber according to the present invention, the content of benzo (a) pyrene is 1 mass ppm or less.
Since benzo (a) pyrene is a carcinogen, the European Union (EU) stipulates that its content be 1 ppm by mass or less. Also in the present invention, since the content thereof is 1 ppm by mass or less, there is no concern about carcinogenicity, and it is possible to provide a process oil for rubber excellent in safety.

(B) Content of specific aromatic compound (total concentration):
The process oil for rubber of the present invention has a specific aromatic compound content (total concentration) of 10 mass ppm or less. Here, the specific aromatic compound is benzo (a) anthracene, chrysene and triphenylene, benzo (b) fluoranthene, benzo (k) fluoranthene, benzo (j) fluoranthene, benzo (e) pyrene, benzo (a) pyrene, And 8 types of dibenzo (a, h) anthracene. These are all highly carcinogenic substances, and the EU has specified that the content be 10 mass ppm or less. Also in the present invention, since the content (total concentration) is 10 mass ppm or less, it is possible to provide a rubber process oil excellent in safety without worrying about carcinogenicity. These concentrations can be measured by the following method.

(Method for measuring the concentration of specific aromatic compounds)
1 g of a sample is dissolved in hexane in a 50 ml flask to prepare a 2% by mass sample solution. 1 ml of this sample solution is loaded on 5 g of 5% by mass water-containing silica gel, washed with 20 ml of hexane, and the target component adsorbed with 50 ml of hexane solution containing 5 vol% acetone is eluted. After concentrating the eluate to 1 ml, 1 μg of chrysene d ₁₂ or benzo (a) pyrene d ₁₂ is added as an internal standard substance and analyzed by a gas chromatograph mass spectrometer.

(C) Polycyclic aromatic hydrocarbon (PCA) content:
The process oil for rubber of the present invention has a PCA content of less than 3% by mass and preferably less than 2.5% by mass. Because of the carcinogenic problem, since mineral oil with a PCA of 3% by mass or more is restricted in handling in Europe and the like, it is preferable that the process oil for rubber of the present invention also has a PCA of less than 3% by mass. is there. By making this PCA less than 3% by mass, it is possible to provide a process oil for rubber that is excellent in safety without worrying about carcinogenicity.
The PCA content of the process oil for rubber may be measured in accordance with the IP346 (92) method defined by the British Petroleum Institute.

In addition, the process oil for rubber of the present invention preferably further has the following properties in (d) kinematic viscosity (100 ° C.), (e) aniline point, (f) flash point, and (g) aromatic content. These will be described below.
(D) Kinematic viscosity (100 ° C.):
Rubber processing oil of the present invention is preferably a kinematic viscosity at 100 ° C. is 20 to 80 mm ² / s, more preferably 30 to 60 mm ² / s. If the kinematic viscosity is 20 mm ² / s or more, the normal physical properties of the blended rubber will not be lowered. On the other hand, if the kinematic viscosity is 80 mm ² / s or less, molding processability and The operability is not adversely affected and the rubber properties are good.
The kinematic viscosity at 100 ° C. of the process oil for rubber may be measured in accordance with ASTM-D445.

(E) Aniline point:
The process oil for rubber of the present invention preferably has an aniline point of 95 ° C. or lower, more preferably 60 to 90 ° C. When the aniline point is 95 ° C. or lower, the compatibility with the rubber is not deteriorated, and the process oil for rubber does not bleed on the rubber surface. The lower limit of the aniline point is not particularly limited. However, if the temperature is lower than 60 ° C., the PCA content becomes high and may exceed 3% by mass as a reference, so care must be taken. What is necessary is just to measure the aniline point of the process oil for rubber | gum based on ASTM-D611.

(F) Flash point:
The process oil for rubber of the present invention preferably has a flash point of 240 ° C. or higher, and more preferably 260 ° C. or higher. If the flash point is 240 ° C., there is little risk of safety problems due to evaporation and adverse effects on the environment.
In addition, what is necessary is just to measure the flash point of the process oil for rubber | gum based on ASTM-D92.
(G) Aromatic content Furthermore, the process oil for rubber of the present invention preferably has an aromatic content (% C _A ) of 15 to 35. If% C _A is 15 or more, the process oil for rubber is not likely to bleed on the rubber surface, and if% C _A is 30 or less, the PCA content does not exceed 3% by mass. The aromatic content may be measured according to ASTM D2140.

  The second process oil for rubber of the present invention is a rubber process oil (A) comprising the extract (A1) and / or raffinate (A2) described above, and (B) a polycyclic aromatic hydrocarbon (PCA). A lubricating base oil having a content of less than 3% by mass is mixed. Thereby, it becomes easy to adjust properties such as kinematic viscosity and aniline point of the process oil for rubber, and the rubber physical properties of the process oil can be further improved.

The lubricating base oil having a PCA content of less than 3% by mass (B) is obtained by, for example, reducing the vacuum gas oil fraction obtained by subjecting a paraffinic crude oil or a naphthenic crude oil to atmospheric distillation and vacuum distillation. Can be obtained by solvent purification or hydrorefining so as to be less than 3% by mass. Moreover, when using paraffin type | system | group crude oil, it is preferable to use what carried out the solvent dewaxing or the hydrodewaxing process, and improved the fluidity | liquidity.
(B) The lubricating base oil has a benzo (a) pyrene of 1 mass ppm or less, a specific aromatic compound content of 10 mass ppm or less, a kinematic viscosity (100 ° C.) of 5 to 40 mm ² / s, a flash point. Is preferably 200 ° C. or higher. If a lubricating base oil satisfying such properties is used, it is possible to easily adjust a rubber process oil having good rubber properties and excellent safety without worrying about carcinogenicity.

In the rubber process oil of the present invention, the property of the rubber process oil in which the rubber process oil (A) is blended with the (B) lubricating base oil is the same as that of the rubber process oil (A). ) To (c), and (d) to (g) are preferably satisfied.
Further, in the process oil for rubber of the present invention, when the process oil for rubber (A), that is, the process oil for rubber comprising (A1) and / or (A2) is blended with the lubricant base oil (B). The mixing ratio of the two is not particularly limited and is arbitrary, but the volume mixing ratio of the process oil for rubber (A) and the lubricating base oil of (B) is 99/1 to 50/50. It is preferable that the ratio is 95/5 to 50/50. By setting the volume mixing ratio of the base material of (A) and the lubricating base oil of (B) within such a range, rubber having the properties of (a) to (c) and (d) to (g) It becomes easy to obtain process oil.

Below, an example of the preferable manufacturing method of the above-mentioned process oil for rubber | gum of this invention is demonstrated.
[Degreasing oil adjustment process]
The degreased oil used as the raw material of the present invention may be obtained by removing the vacuum distillation residue oil obtained by atmospheric distillation and vacuum distillation of paraffinic crude oil.
Here, the methods of atmospheric distillation and vacuum distillation are not limited, and known apparatuses and methods can be used. However, since the 1% by volume distillation temperature of the vacuum residue oil in the distillation property is required to be 380 ° C. or higher, the conditions for vacuum distillation are limited within a range where this can be achieved.
In addition, the vacuum distillation residue oil is removed by separating into an asphalt component and an oil component using a solvent such as liquefied propane (or a liquefied propane / butane mixed solvent), for example, and the oil component is separated as a desorbed oil. The devolatilization with liquefied propane is, for example, mixed with liquefied propane 3 to 6 times to the vacuum distillation residue oil, and the extraction temperature is tower top / column bottom = 85 to 105 ° C./60 to 75 ° C. Should be extracted. This defragmentation oil preferably has a polycyclic aromatic hydrocarbon (PCA) content of less than 3% by mass.

[First solvent extraction step]
In the first solvent extraction step, the raffinate and the extract are obtained by solvent extraction using a depolarized oil as a raw material and a polar solvent. Here, as a polar solvent that can be used, N-methylpyrrolidone (N-methyl-2-pyrrolidone: NMP), furfural, phenol, sulfolane, dimethyl sulfoxide, and the like can be used. In particular, N-methylpyrrolidone and furfural are used. It is preferable to use it.
In the solvent extraction, the solvent ratio (solvent / dewetting oil volume ratio) is preferably in the range of 0.5 to 10, particularly preferably in the range of 1.0 to 2.0. preferable. In this case, the extraction temperature is preferably 60 to 150 ° C, and particularly preferably 80 to 120 ° C.

[Second solvent extraction step]
In the second solvent extraction step, the extract obtained in the first solvent extraction step is further subjected to a second solvent extraction (2a-1) to obtain a raffinate, and / or the first solvent extraction. In this step, the raffinate obtained in (2) is further subjected to second solvent extraction (2a-2) to obtain an extract.
The extraction conditions in the solvent extraction step (2a-1) and the solvent extraction step (2a-2) are preferably performed in the same condition range as that shown as the extraction condition in the first solvent extraction step.

Regarding the relationship between the first solvent extraction and the second solvent extraction, the conditions for the first extraction are set constant, and the conditions for the second solvent extraction are matched with the properties required for the rubber process oil (A). It is preferable to change the method. In particular, a method in which the first extraction conditions are set to conditions suitable for production of a normal lubricating base oil, which is a by-product, and the second solvent extraction conditions are appropriately selected is preferable. By doing in this way, this invention can be implemented, without changing the manufacturing conditions of the lubricating base oil (the raffinate of the 1st solvent extraction) widely used conventionally.
As a more specific example of solvent extraction, the first solvent extraction and the second solvent extraction both use N-methylpyrrolidone or furfural as a solvent, a solvent ratio of 1.0 to 2.0, and an extraction temperature. This is a method performed at 80 to 120 ° C.

[Lubrication base oil mixing process]
As the lubricating base oil in the case of producing the process oil for rubber by mixing the base oil of (B) with the raffinate of (A1) and / or the extract of (A2), the content of PCA is 3 mass. %, Preferably, benzo (a) pyrene is 1 mass ppm or less, the content of the specific aromatic compound is 10 mass ppm or less, the kinematic viscosity (100 ° C.) is 5 to 40 mm ² / s, and the flash point is 200. It is preferable that the temperature is not lower than ° C.

  Such lubricating base oils are, for example, distillate oils obtained by atmospheric distillation of paraffinic crude oils, intermediate crude oils or naphthenic crude oils, or by distilling residual oil of atmospheric distillation under reduced pressure ( It can be obtained by purifying the decoction oil obtained by devolatilizing the vacuum oil) or the residual oil according to a conventional method. For example, solvent refined oil, hydrogenated refined oil, etc. can be mentioned. By preparing the purification conditions of these purification methods, a lubricating base oil having the properties described above can be obtained. In addition, you may perform a dewaxing process and a white clay process suitably for refined oil. In particular, a base oil obtained by subjecting a vacuum gas oil obtained by distillation of crude oil under reduced pressure to solvent extraction and / or hydrorefining, or solvent extraction and / or hydrorefining and further dewaxing treatment is preferred.

  The mixing ratio of the lubricant base oil of (B) to the process oil for rubber (A) is not particularly limited, but the volume mixing ratio of the process oil for rubber (A) and the lubricant base oil of (B) is 99/1 to 50/50, preferably 95/5 to 50/50 (the blending ratio of the lubricating base oil (B) is 5 to 50% by volume with respect to the total amount of rubber process oil). More preferred. By setting the volume mixing ratio of (A) and (B) to 99/1 to 50/50, the process oil for rubber having the properties (a) to (g) can be easily adjusted.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by these examples.

[Example 1] and [Example 2]
(Escape process)
Depressurized residual oil after middle-eastern crude oil is distilled at atmospheric pressure to remove fuel oil such as kerosene and light oil, and after distillation under reduced pressure to atmospheric pressure residual oil that has flowed out from the bottom of the distillation column Was used as a starting material. The vacuum residue oil is degassed with propane as a solvent at a solvent ratio of 5.5 and a predetermined extraction temperature (top 90 ° C., bottom 65 ° C.), and the degassed oil yield is 35% by volume. Oil Z was obtained. Properties are shown in Table 1.

(First solvent extraction step)
The defragmentation oil obtained in the deburring process was extracted with N-methylpyrrolidone (NMP) as a solvent at a solvent ratio of 1.0 and an extraction temperature of 110 ° C. to obtain raffinate R1 and extract E1. Properties are shown in Table 1.

(Second solvent extraction step)
Extract E1 was extracted using NMP as a solvent at a solvent ratio of 1.5 and an extraction temperature of 100 ° C. to obtain raffinate R2. This R2 was used as the rubber process oil of Example 1 in the present invention. The raffinate R1 was extracted with NMP as a solvent at a solvent ratio of 1.5 and an extraction temperature of 120 ° C. to obtain Extract E2. This E2 was used as the process oil for rubber of Example 2 in the present invention. Properties are shown in Table 2.
Example 3

(Mixing process)
Lubricant base oil B1 (characterized by hydrocracking and dewaxing a vacuum gas oil fraction obtained by atmospheric distillation and vacuum distillation of Middle Eastern crude oil) having the properties shown in Table 1 is applied to the extract R2. 40% by volume was mixed to obtain a mixed oil having a kinematic viscosity at 100 ° C. of about 25 mm ² / s (volume mixing ratio 60/40). This mixed oil was used as rubber process oil of Example 3 according to the present invention. Properties are shown in Table 2.
Example 3

The extract E2 obtained in Example 1 was mixed with lubricating base oil B2 having the properties shown in Table 1 (atmospheric distillation of Australian naphthenic crude oil and vacuum gas oil fraction obtained by distillation under reduced pressure using furfural. And 40% by volume of the solvent) was mixed to obtain a mixed oil having a kinematic viscosity at 100 ° C. of about 22.4 mm ² / s (volume mixing ratio 60/40). This mixed oil was used as the process oil for rubber of Example 4 according to the present invention. Properties are shown in Table 2.

[Comparative Example 1]
E1 obtained in Example 1 was used as the process oil for rubber of Comparative Example 1.

As can be seen from the results in Table 2, the rubber process oils of Examples 1 to 4 are all benzo (a) pyrene, specific aromatic compound content and polycyclic aromatic hydrocarbon (PCA) content. They are low and have no carcinogenic problem. They have a kinematic viscosity at 40 ° C. of ²⁰ to 60 mm ² / s and an aniline point of 75 to 90 ° C. Can be maintained.
On the other hand, the extract used as the process oil for rubber of Comparative Example 1 has a high PCA, and thus becomes a process oil for rubber having a carcinogenicity or safety problem.

  The process oil for rubber of the present invention is a processing oil for natural rubber and synthetic rubber, a spreading agent, a plasticizer for a thermoplastic resin, a printing ink component, a softening agent for modified asphalt for pavement, particularly a tire rubber. Can be advantageously used as a process oil. Moreover, the process oil for rubber of the present invention has great utility value because it is not necessary to change the production process of the by-product lubricating base oil.

Claims (5)

1% by volume distillation temperature obtained from paraffinic crude oil is 380 ° C. or higher, and the defragmentation oil obtained by degassing is used as a raw material, and the first solvent extraction is performed to obtain raffinate and extract. Then
(A1) An extract obtained by further subjecting the raffinate to a second solvent extraction and / or (A2) An extract obtained by the first solvent extraction being obtained by further subjecting the raffinate to a second solvent extraction. Raffinate,
A rubber process oil comprising the following properties (a) to ( d ):
(A) Benzo (a) pyrene 1 mass ppm or less (b) Content of specific aromatic compound 10 mass ppm or less (c) Polycyclic aromatic hydrocarbon (PCA) content Less than 3 mass%
(D) Aromatic content (% C _A ) 15-35
  Both the first solvent extraction and the second solvent extraction were carried out using N-methylpyrrolidone or furfural as a solvent under a solvent ratio of 1.0 to 2.0 and an extraction temperature of 80 to 120 ° C. The process oil for rubber according to claim 1, wherein   Furthermore, the process oil for rubber | gum of Claim 1 or 2 formed by mix | blending (B) lubricating base oil with a polycyclic aromatic hydrocarbon (PCA) content of less than 3 mass%. (B) Lubricating oil base oil is benzo (a) pyrene 1 mass ppm or less, specific aromatic compound content 10 mass ppm or less, kinematic viscosity (100 ° C.) 5-40 mm ² / s, flash point 200 ° C. or more. The process oil for rubber according to claim 3, wherein   The process oil for rubber according to claim 3 or 4, wherein the blending ratio of the lubricating base oil (B) is 5 to 50% by volume with respect to the total amount of process oil for rubber.