Hydrogenated petroleum resin pellet and method for producing hydrogenated petroleum resin pellet

Abstract

To provide a hydrogenated petroleum resin pellet with low odor and a method for producing the same.SOLUTION: A hydrogenated petroleum resin pellet having an emission amount of a volatile component of 10 ppm by mass or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to hydrogenated petroleum resin pellets and a method for producing hydrogenated petroleum resin pellets. [Background technology]

[0002] BACKGROUND ART In recent years, hot melt adhesives containing a thermoplastic compound as a base polymer and additives such as a tackifier have been used in a variety of fields, such as the manufacture of sanitary products, bookbinding, and various types of packaging.

[0003] Examples of thermoplastic compounds that serve as the base polymer of hot melt adhesives include natural rubber, ethylene-vinyl acetate copolymer (EVA), amorphous polyalphaolefin, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and styrene-ethylene-butylene-styrene rubber (SEBS) and styrene-ethylene-propylene-styrene rubber (SEPS), which are obtained by hydrogenating these rubber components.

[0004] Furthermore, examples of tackifiers used as additives for hot melt adhesives include rosin resins, terpene resins, petroleum resins, and hydrogenated versions of these. Among these, petroleum resins, especially hydrogenated petroleum resins, are preferably used because they are suitable for industrial production and have high quality stability.

[0005] Hot melt adhesives containing hydrogenated petroleum resins as tackifiers have been used up to now. In particular, when hot melt adhesives are used in the production of sanitary products such as disposable diapers, there are concerns that the odors caused by volatile organic compounds (VOCs) contained in the products can cause discomfort to users and have adverse health effects, and various studies are being conducted to address this issue.

[0006] For example, Patent Document 1 discloses petroleum resins and hydrogenated petroleum resins that have low volatile organic compound components and are excellent in low odor, and that have a volatile organic compound component content of less than 100 wtppm. Patent Document 2 discloses a method for deodorizing hydrogenated petroleum resin, which is characterized by stripping the hydrogenated petroleum resin at a specific gas flow rate, with the aim of effectively reducing odorous components coexisting in the hydrogenated petroleum resin and adjusting the softening point to an appropriate range. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 172434 [Patent Document 2] International Publication No. 2019 / 189296 Summary of the Invention [Problem to be solved by the invention]

[0008] Patent Documents 1 and 2 disclose that low-odor hydrogenated petroleum resins can be obtained, but do not describe how the obtained resins can be commercialized. When hydrogenated petroleum resins are used in hot melt adhesives, etc., as described above, they must be manufactured in a form that is easy to compound. In particular, they are usually manufactured as pellets, which are easy to transport and measure. However, odorous components are generated during the process from the devolatilization treatment to pelletization to obtain low-odor hydrogenated petroleum resins, and the odor of the resulting resin pellets can be a problem. Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide hydrogenated petroleum resin pellets with little odor and a method for producing the same. [Means for solving the problem]

[0009] As a result of intensive research in light of the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by hydrogenated petroleum resin pellets having a volatile component emission amount of not more than a specific amount and a production method for obtaining the same, and have thus completed the present invention. That is, the present invention is as follows.

[0010] [1] Hydrogenated petroleum resin pellets with a volatile component emission level of 10 mass ppm or less, as defined below. Amount of volatile components emitted The amount of all components having a retention time shorter than the retention time of normal dodecane as measured by headspace gas chromatography, converted into ethylcyclohexane, relative to the hydrogenated petroleum resin. [2] Hydrogenated petroleum resin pellets according to [1], in which the emission amount of the main cracked components defined below is 5 ppm by mass or less. Emission amount of main decomposition components The amount of tricyclodecenes and styrene converted into ethylcyclohexane relative to the hydrogenated petroleum resin measured by headspace gas chromatography. [3] The hydrogenated petroleum resin pellets according to [2], wherein the tricyclodecenes are tricyclo-3-decene and tricyclo-8-decene. [4] The hydrogenated petroleum resin pellets according to [2] or [3], wherein the amount of volatile components emitted is 5 ppm by mass or less, and the amount of main cracked components emitted is 3 ppm by mass or less. [5] The hydrogenated petroleum resin pellet according to any one of [1] to [4], wherein the hydrogenated petroleum resin constituting the hydrogenated petroleum resin pellet contains a hydrogenated copolymer of a cyclopentadiene compound and a vinyl aromatic compound. [6] The hydrogenated petroleum resin pellet according to [5], wherein the copolymer is obtained by thermally polymerizing a cyclopentadiene compound and a vinyl aromatic compound. [7] The hydrogenated petroleum resin pellet according to [6], wherein the cyclopentadiene compound is at least one selected from the group consisting of cyclopentadiene and dicyclopentadiene. [8] A method for producing hydrogenated petroleum resin pellets, comprising: step 1 of devolatilizing a hydrogenated petroleum resin in a devolatilizing device; step 2 of transferring the hydrogenated petroleum resin from the devolatilizing device to a molding device for pelletizing; and step 3 of obtaining hydrogenated petroleum resin pellets in the molding device for pelletizing, A method for producing hydrogenated petroleum resin pellets, wherein the temperature from the end of step 1 to the time when hydrogenated petroleum resin pellets are obtained in step 3 is 235°C or less, and the time from the end of step 1 to the time when hydrogenated petroleum resin pellets are obtained in step 3 is 1 hour or less. [9] The method for producing hydrogenated petroleum resin pellets according to [8] above, wherein the temperature from the end of step 1 to the time of obtaining hydrogenated petroleum resin pellets in step 3 is 230°C or less, and the time from the end of step 1 to the time of obtaining hydrogenated petroleum resin pellets in step 3 is 40 minutes or less.

[10] A method for producing hydrogenated petroleum resin pellets, comprising: step 1 of devolatilizing a hydrogenated petroleum resin in a devolatilizing device; step 2 of transferring the hydrogenated petroleum resin from the devolatilizing device to a molding device for pelletizing; and step 3 of obtaining hydrogenated petroleum resin pellets in the molding device for pelletizing, A method for producing hydrogenated petroleum resin pellets, in which an index value is set so that the amount of volatile components emitted from the obtained hydrogenated petroleum resin pellets does not exceed a target value, and steps 2 and 3 are carried out so that the temperature (T) and time (t) from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3 satisfy the following formula (1): t × [exp(AE / RT)] ≦ index value (1) (where A is the frequency factor, E is the activation energy, and R is the gas constant.)

[11] The method for producing hydrogenated petroleum resin pellets according to

[10] , wherein the frequency factor A and the activation energy E are represented by the following formulas (2) and (3): A=C 21 ×μ 2 +C 11 ×μ+C 01 (2) E=C 22 ×μ 2 +C 12 ×μ+C 02 (3) (where μ is the viscosity of the hydrogenated petroleum resin at 200°C, and C 21 , C 11 , C 01 , C 22 , C 12 , C 02 are the coefficients.)

[12] The method for producing hydrogenated petroleum resin pellets according to any one of [8] to

[11] above, wherein the amount of volatile components emitted from the hydrogenated petroleum resin at the end of step 1 is 5 mass ppm or less.

[13] The method for producing hydrogenated petroleum resin pellets according to any one of

[10] to

[12] above, wherein the target value for the amount of volatile components emitted from the hydrogenated petroleum resin pellets is 10 mass ppm or less. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide hydrogenated petroleum resin pellets with little odor and a method for producing the same. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of a pelletizing molding device used in the method for producing hydrogenated petroleum resin pellets of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Hydrogenated petroleum resin pellets] The hydrogenated petroleum resin pellets of the present invention have an emission amount of volatile components, as defined below, of 10 mass ppm or less. Amount of volatile components emitted The amount of all components having a retention time shorter than the retention time of normal dodecane as measured by headspace gas chromatography, converted into ethylcyclohexane, relative to the hydrogenated petroleum resin.

[0014] (Hydrogenated petroleum resin and its manufacturing method) The hydrogenated petroleum resin pellets of the present invention are composed of a hydrogenated petroleum resin, and the hydrogenated petroleum resin constituting the hydrogenated petroleum resin pellets preferably contains a hydrogenated copolymer of a cyclopentadiene compound and a vinyl aromatic compound, and more preferably is a hydrogenated copolymer of a cyclopentadiene compound and a vinyl aromatic compound. The copolymer is preferably one obtained by thermally polymerizing a cyclopentadiene compound and a vinyl aromatic compound. Furthermore, the cyclopentadiene compound is more preferably at least one selected from the group consisting of cyclopentadiene and dicyclopentadiene. The method for obtaining the hydrogenated petroleum resin constituting the hydrogenated petroleum resin pellets of the present invention is not particularly limited, but it is preferable that the resin be obtained by carrying out the copolymerization reaction and hydrogenation reaction shown below.

[0015] <Copolymerization reaction step> In the copolymerization reaction, it is preferable to use a polymerization reaction vessel equipped with a heating device, a pressurizing device, and a stirring device, and to use a cyclopentadiene compound as the first raw material and a vinyl aromatic compound as the second raw material.The cyclopentadiene compound and the vinyl aromatic compound are then copolymerized in a polymerization solvent under predetermined conditions to produce a copolymer (hereinafter also referred to as a petroleum resin). Here, the copolymer is preferably obtained by thermally polymerizing a cyclopentadiene compound and a vinyl aromatic compound. More specifically, the copolymer is preferably obtained by thermally polymerizing at least one selected from the group consisting of cyclopentadiene and dicyclopentadiene with styrene.

[0016] The polymerization reaction tank may be connected to a first raw material tank, a second raw material tank, and a polymerization solvent tank. The first raw material tank and the second raw material tank store the first raw material and the second raw material, respectively, and the polymerization solvent tank stores the polymerization solvent. The polymerization reaction tank can be designed so that first, the polymerization solvent is supplied from the polymerization solvent tank, and then the first raw material and the second raw material are supplied appropriately from the first raw material tank and the second raw material tank, respectively. Also, an opening and closing port can be provided at the bottom of the polymerization reaction tank so that the copolymer produced in the copolymerization reaction can be discharged to the outside. When the first raw material and the second raw material are mixed in advance, the number of raw material tanks may be one.

[0017] Examples of the cyclopentadiene compound include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, and dimers and co-dimers thereof, and at least one selected from the group consisting of cyclopentadiene and dicyclopentadiene is more preferred. Examples of the vinyl aromatic compound include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, and ethylindene.

[0018] The cyclopentadiene compound and the vinyl aromatic compound may be fed to the polymerization reactor individually, or they may be mixed together in advance to form a monomer mixture, which is then fed to the polymerization reactor. The mixing ratio of the cyclopentadiene compound and the vinyl aromatic compound is not particularly limited, but the mass ratio of the cyclopentadiene compound:vinyl aromatic compound is preferably 70:30 to 20:80, more preferably 60:40 to 40:60.

[0019] Typical examples of the polymerization solvent used in the copolymerization reaction of a cyclopentadiene compound and a vinyl aromatic compound include aromatic solvents, naphthenic solvents, aliphatic hydrocarbon solvents, etc. Specific examples of the polymerization solvent that are preferably used include toluene, xylene, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, etc. The amount of the polymerization solvent used is preferably 50 to 500 parts by mass, more preferably 60 to 300 parts by mass, even more preferably 60 to 200 parts by mass, and even more preferably 70 to 150 parts by mass, relative to 100 parts by mass of the monomer mixture.

[0020] From the viewpoint of smoothly initiating thermal polymerization, it is preferable that the polymerization solvent supplied to the polymerization reaction tank is preheated to a temperature of preferably 100° C. or higher, more preferably 150° C. or higher, and even more preferably 200° C. or higher. It is preferable that a monomer mixture of a cyclopentadiene compound and a vinyl aromatic compound is added to the preheated polymerization solvent in this manner, and the copolymerization reaction is carried out under predetermined conditions while stirring. Here, the monomer mixture is preferably added in portions or continuously from the viewpoint of controlling heat generation due to polymerization. It is preferable that the amounts of the divided monomer mixture added are equal. In the addition of the monomer mixture, the time required from the start to the end of the addition is preferably 0.5 to 5 hours, more preferably 1 to 3 hours. It is preferred to continue the copolymerization reaction even after the addition of the monomer mixture is completed. The predetermined conditions for the copolymerization reaction are not particularly limited, but the reaction temperature is usually 150 to 350°C, and preferably 220 to 300°C, the reaction pressure is usually 0 to 2 MPaG, and preferably 0 to 1.5 MPaG, and the reaction time is usually 1 to 10 hours, preferably 1 to 8 hours, and more preferably 1 to 5 hours.

[0021] The physical properties of the copolymer thus obtained are preferably a softening point of 50 to 120°C, a vinyl aromatic compound unit content of 30 to 90 mass%, a bromine number of 30 to 90 g / 100 g, and a number average molecular weight of 400 to 1100. Specifically, the softening point, vinyl aromatic compound unit content, bromine number, and number average molecular weight can be measured by the same method as that for the hydrogenated petroleum resin at the end of Step 1 (after the devolatilization step) described later in the Examples.

[0022] <Hydrogenation reaction process> The hydrogenated petroleum resin constituting the hydrogenated petroleum resin pellets of the present invention is preferably produced by, for example, employing a hydrogenation reaction vessel equipped with a heating device and a pressurizing device, dissolving the copolymer obtained by the copolymerization reaction in a hydrogenation solvent, adding hydrogen under predetermined conditions in the presence of a hydrogenation reaction catalyst as needed, and carrying out a hydrogenation reaction to produce a hydrogenated petroleum resin. Thus, the hydrogenated petroleum resin specified in the present invention is preferably obtained by hydrogenating (hydrogen addition) the copolymer (petroleum resin) obtained by the copolymerization reaction described above. When the hydrogenated petroleum resin contains aromatic rings as constituent components, it is preferable that the aromatic rings are also hydrogenated (hydrogen added). The hydrogenated petroleum resin may be a partially hydrogenated type in which the petroleum resin is partially hydrogenated, or a fully hydrogenated type in which the petroleum resin is completely hydrogenated.

[0023] Examples of the hydrogenation solvent include cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, and tetrahydrofuran.

[0024] The method for dissolving the copolymer obtained by the copolymerization reaction in a hydrogenation solvent and supplying the resulting solution to the hydrogenation reaction tank is not particularly limited. For example, the copolymer and the hydrogenation solvent may be supplied separately to the hydrogenation reaction tank and dissolved therein, or they may be mixed together in advance to form a dissolved mixture, which is then supplied to the hydrogenation reaction tank. The mixing ratio of the petroleum resin to the hydrogenation solvent used is not particularly limited, but the mass ratio of petroleum resin:hydrogenation solvent is preferably 10:90 to 50:50, more preferably 20:80 to 40:60.

[0025] Examples of the hydrogenation catalyst used in the hydrogenation reaction include nickel, palladium, cobalt, platinum, and rhodium.

[0026] The predetermined conditions for the hydrogenation reaction are not particularly limited, but the hydrogen supply pressure is usually 1.0 to 6.0 MPaG, the reaction temperature is usually 120 to 300°C, preferably 150 to 250°C, and the reaction time is usually 1 to 17 hours, preferably 2 to 15 hours. The hydrogenated petroleum resin obtained by the above hydrogenation reaction preferably has a viscosity of 0.01 to 1.0 Pa·s measured at the treatment temperature in Step 1 (devolatilization step) described below in accordance with the Japan Adhesives Industry Association standard "Hot Melt Adhesion Test Method" JAI-7-1999. When the viscosity of the hydrogenated petroleum resin obtained by the hydrogenation reaction is within the above range, volatile organic compound components can be efficiently removed in the devolatilization step described below. In the present invention, the hydrogenated petroleum resin obtained at the end of Step 1 (after the devolatilization step) described below, i.e., the hydrogenated petroleum resin from which volatile organic compound components have been removed, may also be referred to simply as hydrogenated petroleum resin for convenience.

[0027] (Properties of hydrogenated petroleum resin pellets) The hydrogenated petroleum resin pellets of the present invention have an emission amount of volatile components, as defined below, of 10 mass ppm or less. Amount of volatile components emitted The amount of all components having a retention time shorter than the retention time of normal dodecane as measured by headspace gas chromatography, converted into ethylcyclohexane, relative to the hydrogenated petroleum resin. It is also preferable that the material has the following properties:

[0028] From the viewpoint of odor suppression, the amount of volatile components emitted is 10 ppm by mass or less, and preferably 5 ppm by mass or less. Furthermore, the hydrogenated petroleum resin pellets of the present invention preferably have an emission amount of the main cracked components defined below of 5 ppm by mass or less, more preferably 3 ppm by mass or less. Emission amount of main decomposition components The amount of tricyclodecenes and styrene converted into ethylcyclohexane relative to the hydrogenated petroleum resin measured by headspace gas chromatography. Examples of tricyclodecenes include tricyclo-3-decene and tricyclo-8-decene.

[0029] From the viewpoint of odor suppression, the amount of the main decomposition components emitted is preferably 5 ppm by mass or less, and more preferably 3 ppm by mass or less. That is, it is preferable that the amount of the volatile components emitted is 10 ppm by mass or less, and the amount of the main decomposition components emitted is 5 ppm by mass or less, and it is more preferable that the amount of the volatile components emitted is 10 ppm by mass or less, preferably 5 ppm by mass or less, and the amount of the main decomposition components emitted is 3 ppm by mass or less. The amount of volatile components released and the amount of main decomposition components released can be measured by the method described in the Examples section, where the heating temperature is 150°C and the heating time is 20 minutes.

[0030] The shape and size of the hydrogenated petroleum resin pellets of the present invention may be adjusted according to the application and are not particularly limited, but examples of the shape include spherical, approximately spherical, oval sphere, approximately oval sphere, hemisphere, cylinder, approximately cylinder, rectangular parallelepiped, flake, etc., with spherical, approximately spherical, oval sphere, approximately oval sphere, cylinder, approximately cylinder, and hemisphere being preferred, and spherical, approximately spherical, oval sphere, approximately oval sphere, and hemisphere being more preferred. Having a rounded outer edge results in excellent flowability, blendability, and transportability. The maximum length of the size is preferably 1 to 100 mm, more preferably 3 to 50 mm, and even more preferably 5 to 20 mm.

[0031] The hydrogenated petroleum resin pellets of the present invention having the above-mentioned properties are easy to blend and have little odor, and therefore can be particularly suitably used as a raw material for hot melt adhesives. Hot melt adhesives containing the hydrogenated petroleum resin pellets of the present invention as a raw material are used in a variety of fields, such as sanitary products, various packaging applications, bookbinding, textiles, woodworking, electrical materials, can making, construction, bag making, and road binders, and because they have little odor, they can be particularly suitably used in sanitary products such as disposable diapers.

[0032] [Method of manufacturing hydrogenated petroleum resin pellets] The hydrogenated petroleum resin pellets of the present invention may be produced by any method as long as the amount of volatile components emitted is 10 mass ppm or less as defined above. However, they are preferably produced by the following method. That is, the method for producing hydrogenated petroleum resin pellets of the present invention is a method comprising step 1 of devolatilizing hydrogenated petroleum resin in a devolatilizing apparatus, step 2 of transferring the hydrogenated petroleum resin from the devolatilizing apparatus to a molding apparatus for pelletizing, and step 3 of obtaining hydrogenated petroleum resin pellets in the molding apparatus for pelletizing, wherein the temperature from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3 is preferably 235°C or less, and the time from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3 is preferably 1 hour or less. Among these, a method in which the temperature from the end of step 1 to the preparation of hydrogenated petroleum resin pellets in step 3 is 230°C or less, and the time from the end of step 1 to the preparation of hydrogenated petroleum resin pellets in step 3 is 40 minutes or less is more preferred.

[0033] Further, as another embodiment of the method for producing hydrogenated petroleum resin pellets of the present invention, there is provided a method for producing hydrogenated petroleum resin pellets, comprising: step 1 of devolatilizing hydrogenated petroleum resin in a devolatilizing apparatus; step 2 of transferring hydrogenated petroleum resin from the devolatilizing apparatus to a molding apparatus for pelletizing; and step 3 of obtaining hydrogenated petroleum resin pellets in the molding apparatus for pelletizing, It is also preferable that the method for producing hydrogenated petroleum resin pellets includes setting an index value so that the amount of volatile components emitted from the obtained hydrogenated petroleum resin pellets does not exceed a target value, and performing steps 2 and 3 so that the temperature (T) and time (t) from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3 satisfy the following formula (1): t × [exp(AE / RT)] ≦ index value (1) (where A is the frequency factor, E is the activation energy, and R is the gas constant.) It is also preferable that the frequency factor A and activation energy E in the formula (1) are represented by the following formulas (2) and (3). A=C 21 ×μ 2 +C 11 ×μ+C 01 (2) E=C 22 ×μ 2 +C 12 ×μ+C 02 (3) (where μ is the viscosity of the hydrogenated petroleum resin at 200°C, and C 21 , C 11 , C 01 , C 22 , C 12 , C 02 are the coefficients.) Here, the viscosity of the hydrogenated petroleum resin refers to the viscosity of the hydrogenated petroleum resin at the end of step 1 (after the devolatilization step). Specifically, the viscosity can be measured by the method described in the examples. In each of the above methods, the amount of volatile components emitted from the hydrogenated petroleum resin at the end of step 1 (after the devolatilization step) is more preferably 5 ppm by mass or less, and even more preferably 1 ppm by mass or less. The "amount of volatile components emitted" in the production method of the present invention has the same meaning as the amount of volatile components emitted as defined above. Each of the preferred manufacturing methods will be described in detail below.

[0034] <Step 1: Devolatilization step> Step 1 is a step of devolatilizing the hydrogenated petroleum resin in a devolatilizer. The method and devolatilization apparatus for reducing volatile organic compound components by devolatilization are not particularly limited, but for example, distillation methods such as (1) thin film distillation and (2) nitrogen stripping can be used alone or in combination.

[0035] (1) Thin-film distillation The thin film distillation may be carried out by any commonly used apparatus without any particular limitation, and for example, a centrifugal thin film distiller may be used. Specifically, the hydrogenated petroleum resin obtained by the hydrogenation reaction, preferably the hydrogenated petroleum resin obtained by removing the unreacted components and recovering and removing the volatile components, is supplied to a thin-film distillation apparatus, and the volatile organic compound components can be removed while the thin-film distillation is carried out under predetermined conditions, if necessary in the presence of an antioxidant. The predetermined conditions for thin-film distillation are not particularly limited, but the treatment temperature is usually 100 to 300° C., the treatment pressure is usually 0.1 to 15 kPa, and the treatment time is usually 5 to 180 minutes.

[0036] (2) Nitrogen stripping The nitrogen stripping may be carried out using any commonly used device without any particular limitation, and for example, a rotary evaporator or a flash drum may be used. Specifically, it is preferable that the hydrogenated petroleum resin obtained through the above-mentioned (1) thin film distillation is mixed with nitrogen in a static mixer and then separated from the nitrogen in a flash drum. The predetermined conditions for nitrogen stripping are not particularly limited, but the treatment temperature is usually 150 to 300°C, the treatment pressure is usually 0.5 to 150 kPa, the nitrogen flow rate is usually 100 to 1,000,000 mL / min per 100 parts by mass of hydrogenated petroleum resin, and the treatment time is usually 10 to 180 minutes.

[0037] From the viewpoint of reducing the odor of the obtained hydrogenated petroleum resin pellets, the amount of volatile components emitted from the hydrogenated petroleum resin at the end of Step 1 (after the devolatilization step) is preferably 5 ppm by mass or less, and more preferably 1 ppm by mass or less. As described above, in the devolatilization step, a method for reducing the volatile organic compound components contained in the hydrogenated petroleum resin has been described. However, the same method as that for the hydrogenated petroleum resin can also be applied to the petroleum resin to reduce the volatile organic compound components.

[0038] Here, the devolatilization step in thin film distillation and nitrogen stripping is preferably carried out so that the hydrogenated petroleum resin obtained by the hydrogenation reaction contains 6 to 10 mass % of low molecular weight hydrogenated petroleum resin having a molecular weight of about 200 to 350. The content of the low molecular weight hydrogenated petroleum resin having a molecular weight of about 200 to 350 contained in the hydrogenated petroleum resin is preferably 6 to 10 mass %, more preferably 7 to 8 mass %, in the hydrogenated petroleum resin, from the viewpoint of not reducing the tackifying performance of the hydrogenated petroleum resin produced. The physical properties of the hydrogenated petroleum resin obtained in this manner at the end of Step 1 (after the devolatilization step) are preferably a viscosity of 50 to 150 mPa·s, a softening point of 90 to 160°C, a vinyl aromatic compound unit content of 0 to 35 mass%, a bromine number of 0 to 30 g / 100 g, and a number average molecular weight of 500 to 1,100. The viscosity, softening point, vinyl aromatic compound unit content, bromine number, and number average molecular weight can be specifically measured by the methods described in the examples.

[0039] The timing of adding the antioxidant is not particularly limited, but it is preferable to add the antioxidant at a stage before carrying out step 1. Examples of the antioxidant include phenol-based antioxidants and phosphite-based antioxidants. When an antioxidant is used, the amount used is preferably 0.1 to 2.0 parts by mass, more preferably 0.3 to 1.0 part by mass, per 100 parts by mass of the hydrogenated petroleum resin.

[0040] <Step 2: Step of transferring hydrogenated petroleum resin> Step 2 is a step of transferring the hydrogenated petroleum resin from the devolatilizer to a molding device for pelletizing. There are no limitations on the method for transferring the hydrogenated petroleum resin from the devolatilizer to the pelletizing molding apparatus, and examples thereof include a method in which the devolatilizer and the pelletizing molding apparatus are connected by a pipe and the molten hydrogenated petroleum resin is transferred through the pipe, and a method in which the hydrogenated petroleum resin discharged from the devolatilizer is stored in a container, re-melted, and introduced into the pelletizing molding apparatus. However, from the viewpoint of reducing the temperature and time during transfer and obtaining hydrogenated petroleum resin pellets with little odor, the method in which the devolatilizer and the pelletizing molding apparatus are connected by a pipe and the molten hydrogenated petroleum resin is transferred through the pipe is preferred.

[0041] In the method for producing hydrogenated petroleum resin pellets of the present invention, it is preferable to adjust the temperature and time required for this step within specific ranges. The temperature from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3 is preferably 235°C or lower, more preferably 230°C or lower, and even more preferably 225°C or lower. From the viewpoint of properly introducing the hydrogenated petroleum resin into a pelletizing molding device and efficiently obtaining pellets, the temperature is preferably 150°C or higher. The "temperature from the end of step 1 to the time when the hydrogenated petroleum resin pellets are obtained in step 3" mainly refers to the temperature in this step, but also refers to the maximum temperature from the time when the devolatilization operation in the devolatilization apparatus is completed and the hydrogenated petroleum resin becomes available for discharge to the time when the pellets are discharged from the pelletizing molding apparatus. Note that the maximum temperature does not include temporary (for example, for a few minutes) or localized (for example, near the heating apparatus) high temperatures.

[0042] The time from the end of step 1 to obtaining hydrogenated petroleum resin pellets in step 3 is preferably 1 hour or less, more preferably 40 minutes or less, and practically preferably 10 minutes or more. The "time from the end of step 1 to obtaining hydrogenated petroleum resin pellets in step 3" refers mainly to the time required for this step, but also refers to the time during which the hydrogenated petroleum resin is in a molten state and fluid, from the time when the devolatilization operation in the devolatilization apparatus is completed and the hydrogenated petroleum resin becomes available for discharge until the pellets are discharged from the pelletizing molding apparatus. In other words, if heating and cooling are repeated in this step, the time during which fluidity is lost due to cooling is excluded.

[0043] <Step 3: Step of obtaining pellets> Step 3 is a step of obtaining pellets in a pelletizing molding device. There are no limitations on the pelletizing molding device and the method for obtaining pellets, but it is preferable to use the pelletizing molding device shown in Fig. 1. A suitable molding device will be described below with reference to Fig. 1.

[0044] In FIG. 1, a molding device 50 A includes a molding machine main body 52 and a cooling conveyor 53 .

[0045] The molding machine main body 52 is disposed opposite the upstream end in the conveying direction of the cooling conveyor 53. The molding machine main body 52 has a cylindrical body portion 52A having a heating portion (not shown), and a die 52B that ejects molten resin from the outer peripheral surface of the body portion 52A along the axial direction. The molding machine main body 52 also has a cylindrical rotor 52C that rotatably fits onto the outer circumferential surface of the body portion 52A. The rotor 52C has a plurality of discharge holes 52D like a punched metal, and when the rotor 52C rotates around the outer circumferential surface of the body portion 52A and the discharge holes 52D are positioned at the die 52B, the rotor 52C discharges a predetermined amount of molten resin 5A onto the cooling conveyor 53. When this molding apparatus is used, the end point of the temperature and time from the end of step 1 described in the previous step until pellets are obtained in step 3 is the point at which the resin is discharged from discharge hole 52D.

[0046] The cooling conveyor 53 includes a pair of pulleys 53A and a metal belt 53B, which is an endless belt made of metal and rotatably stretched around the pulleys 53A. The cooling conveyor 53 may also be provided with a cooling section 53D that sprays cooling water 53C from the backside of the metal belt 53B to cool the metal belt 53B. The method for cooling the metal belt 53B is not limited to spraying cooling water 53C, but may also be a method of blowing cold air or a method of bringing part of the belt into contact with a heat exchanger.

[0047] It is also preferable to blow cold air directly onto the resin to solidify it. Furthermore, a scraper is preferably provided at the lower end of the metal belt 53B to scrape off the hydrogenated petroleum resin pellets solidified on the metal belt. The pellets thus obtained have a shape of sphere, approximately sphere, oval sphere, approximately oval sphere, or hemisphere.

[0048] The hydrogenated petroleum resin pellets obtained by the production method of the present invention preferably have the properties shown in the section (Properties of Hydrogenated Petroleum Resin Pellets) above. In particular, the amount of volatile components emitted is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less. Furthermore, the amount of main cracked components emitted is preferably 5 ppm by mass or less, more preferably 3 ppm by mass or less.

[0049] <Manufacturing method using index values> In the method for producing hydrogenated petroleum resin pellets of the present invention, it is preferable to set appropriate temperatures and times as described above in the steps from the end of Step 1 to obtaining hydrogenated petroleum resin pellets in Step 3. However, the following index values may also be set for production. By using the index value, it is possible to appropriately adjust the temperature and time from the end of step 1 until the production of hydrogenated petroleum resin pellets in step 3. Specifically, if the temperature from the end of step 1 until the production of hydrogenated petroleum resin pellets in step 3 is high, the time can be set shorter, and if the time from the end of step 1 until the production of hydrogenated petroleum resin pellets in step 3 is long, the temperature can be set lower. That is, as another embodiment, the method for producing hydrogenated petroleum resin pellets of the present invention is a method comprising step 1 of devolatilizing hydrogenated petroleum resin in a devolatilizing apparatus, step 2 of transferring the hydrogenated petroleum resin from the devolatilizing apparatus to a molding apparatus for pelletizing, and step 3 of obtaining hydrogenated petroleum resin pellets in the molding apparatus for pelletizing, wherein an index value is set so that the amount of volatile components emitted from the obtained hydrogenated petroleum resin pellets does not exceed a target value, and steps 2 and 3 are preferably performed so that the temperature (T) and time (t) from the end of step 1 to obtaining pellets in step 3 satisfy the following formula (1): t × [exp(AE / RT)] ≦ index value (1) (where A is the frequency factor, E is the activation energy, and R is the gas constant.)

[0050] The method for determining the coefficients A and E will be explained below. After heat treating hydrogenated petroleum resin at multiple combinations of temperature T and time t, it is analyzed by headspace gas chromatography each time, and the amount of volatile components emitted is measured as an area value S per charged mass obtained by headspace gas chromatography. Based on the multiple experimental results obtained in this way, optimization is performed so that the following relationship (approximate formula) holds for the same A and E. Area per unit charge mass = t × [exp(AE / RT)] Next, the area value per charged mass corresponding to the target ethylcyclohexane-equivalent concentration is determined as an index. As described above, in the present invention, the target ethylcyclohexane-equivalent concentration, i.e., the target value of the amount of volatile components emitted from the hydrogenated petroleum resin pellets, is preferably 10 ppm by mass or less, and more preferably 5 ppm by mass or less. By using the index determined in this way as a standard and setting the control time and temperature so that it is below that index, even if the temperature changes from the devolatilization step (step 1) to the pellet obtaining step (step 3), by controlling it as follows, it is possible to suppress thermal decomposition and keep the amount of volatile components at a specified level.

[0051] An example of the calculation method is shown below. Let time be t (minutes), temperature be T (K), and the area value per unit charged mass obtained from the correlation equation be S (Area / g). The values corresponding to the results of multiple experiments are as follows: t1 T1 S1 t2 T2 S2 ···························· tn Tn Sn Here, the average area value per unit charge mass: Save is expressed as follows: Save={t1×S1+t2×S2+…tn×Sn} / (t1+t2+…+tn) If this value is smaller than the index, the amount of volatile component emission can be suppressed. For example, even if the temperature in part of the process from the devolatilization step to the pelletization step exceeds 235°C, which is the upper limit of the suitable temperature range, by shortening the time, if the average area value per unit charged weight throughout the entire process becomes smaller than the index, the amount of volatile component emission can be controlled to an appropriate level. Thus, although the control method is complicated, it has the advantage of being able to flexibly control temperature and time.

[0052] Next, when applying this to multiple hydrogenated petroleum resins with different viscosities, the frequency factor and activation energy can be expressed as functions using the viscosity (mPa·s) of the hydrogenated petroleum resin at 200°C as follows: Quadratic function of viscosity: C2×μ 2 +C1×μ+C0 Viscosity: μ, coefficient: C2C1C0 However, the above coefficient varies depending on the physical properties of the hydrogenated petroleum resin. That is, using the viscosity of hydrogenated petroleum resin at 200°C, the frequency factor A and activation energy E can be expressed by the following formulas (2) and (3). A=C 21 ×μ 2 +C 11 ×μ+C 01 (2) E=C 22 ×μ 2 +C 12 ×μ+C 02 (3) (where μ is the viscosity of the hydrogenated petroleum resin at 200°C, and C 21 , C 11 , C 01 , C 22 , C 12 , C 02 are the coefficients.)

[0053] In this method, the steps 1, 2, and 3 are preferably carried out by the methods described in the sections <Step 1: Devolatilizing step>, <Step 2: Transferring hydrogenated petroleum resin>, and <Step 3: Obtaining pellets>, respectively.

[0054] The hydrogenated petroleum resin pellets obtained as described above preferably have the properties described in the section (Properties of Hydrogenated Petroleum Resin Pellets). In particular, the amount of volatile components emitted is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less. Furthermore, the amount of main cracked components emitted is preferably 5 ppm by mass or less, more preferably 3 ppm by mass or less. [Example]

[0055] The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0056] [Measurement and Evaluation] <Amount of volatile components emitted and amount of main decomposition components emitted> 0.200 g of the hydrogenated petroleum resin obtained in steps 1 and 2 of the Examples and step 2 of the Comparative Example was collected in a headspace bottle (20 mL) and sealed to prepare a measurement sample. The measurement sample was used to measure the amount of volatile components emitted and the amount of main decomposition components emitted under the following measurement conditions using a gas chromatograph (Agilent 7607A-7890B manufactured by Agilent Technologies). The value of the amount of volatile components emitted was calculated by converting the sum of the peak areas of all components having retention times shorter than that of normal dodecane, a standard product, into a mass when the mass was taken as the standard product of ethylcyclohexane, and expressed as the amount relative to the hydrogenated petroleum resin. The amount of emission of the main cracked components was calculated by converting the total area of the peaks derived from tricyclo-3-decene, tricyclo-8-decene, and styrene into a mass equivalent to a standard ethylcyclohexane, and expressed as the amount relative to the hydrogenated petroleum resin. <Measurement conditions> Headspace Mode: Loop Heating temperature and time: 150℃, 20 minutes Gas chromatogram Column: BPX5 (30m x 0.32mm, film thickness 1.0μm) Oven temperature: 50°C (2 min) to 300°C (15 min) at a rate of 10°C / min Injection temperature: 300℃ Detection temperature: 300℃ Detector: FID Carrier gas: He Flow rate: Constant flow, 1.5mL / min ·Injection volume: 1.0mL Split: 1 / 2

[0057] [Production of hydrogenated petroleum resins] Manufacturing Example 1 (Copolymerization reaction process) 90 parts by mass of xylene as a polymerization solvent was fed into a polymerization reactor equipped with a stirrer and purged with nitrogen, and heated to a temperature of 260°C. To this polymerization reactor, 100 parts by mass of a monomer mixture of a mixture of cyclopentadiene and dicyclopentadiene with styrene (mixing ratio = 1:1 (mass ratio)) was added in equal portions over 3 hours, and a copolymerization reaction was carried out while stirring to maintain the polymerization reaction system at a temperature of 260°C. Thereafter, the copolymerization reaction was continued for 115 minutes while maintaining the temperature at 260°C. A petroleum resin, a copolymer of a cyclopentadiene compound and a vinyl aromatic compound, was obtained as the copolymerization reaction product.

[0058] (Hydrogenation reaction process) The dissolved mixture of the petroleum resin obtained in the copolymerization reaction step and the hydrogenation solvent ethylcyclohexane (mixing ratio = 1:3 (mass ratio)) was supplied to a hydrogenation reactor, and hydrogen was further supplied to the hydrogenation reactor at a hydrogen supply pressure of 5.0 MPaG, and the hydrogenation reaction was carried out at a reaction temperature of 150 to 250°C for 12 hours to obtain a hydrogenated petroleum resin.

[0059] [Production of hydrogenated petroleum resin pellets] Example 1 <Process 1: Devolatilization process> The hydrogenated petroleum resin obtained in the above hydrogenation reaction step was added with 7000 ppm by mass of a phenolic antioxidant (manufactured by BASF, trade name: "Irganox 1010"), and the mixture was supplied to a centrifugal thin-film still ("Horizontal Controller" manufactured by Hitachi Plant Technologies, Ltd.), where thin-film distillation was carried out under the following treatment conditions to remove volatile organic compound components, thereby obtaining a hydrogenated petroleum resin that had undergone thin-film distillation. Processing temperature: 210℃ Processing pressure: 4kPa Processing time: 6 minutes

[0060] 500 g of the hydrogenated petroleum resin that had been subjected to the thin-film distillation was fed to a rotary evaporator, and volatile organic compounds were removed under the following treatment conditions while introducing nitrogen, to obtain a hydrogenated petroleum resin. Processing temperature: 200℃ ·Nitrogen flow rate: 1500mL / min Processing pressure: 100 kPa·s Processing time: 105 minutes

[0061] The properties of the obtained hydrogenated petroleum resin were as follows. The measurement methods are also shown for each item. Softening point: 103.5°C (JIS K2207:2006) Vinyl aromatic compound unit content: 20.3 mass% (infrared spectrophotometer (absorbance 700 cm -1 ) Quantitation by Bromine number: 5.8g / 100g (JIS K2605:1996) Number average molecular weight (Mn): 514 (GPC measurement; column: TSK gel G200HXL & G4000HXL, flow rate: 1 mL / min, eluent: THF, temperature: 40°C) Viscosity: 110 mPa·s (200°C) (Based on the Japan Adhesives Industry Association standard "Hot Melt Adhesion Test Method" JAI-7-1999)

[0062] The hydrogenated petroleum resin obtained in step 1 was used as a sample and heat-treated at multiple temperatures (K) and times (minutes). The area value (Area / g) of the volatile components per charged weight was determined using headspace gas chromatography, and the frequency factor and activation energy were determined from these results using an optimization method. The frequency factor and activation energy were A = 46.0 and E = 43.8 kcal / mol, respectively. Furthermore, the standard for odor insensitivity was set at 5 ppm by mass of volatile component ECH (ethylcyclohexane), and the corresponding index was calculated to be 150. Hereinafter, the following experiments were carried out using this numerical value as the index value in the above formula (1) for the hydrogenated petroleum resin pellets obtained in the examples, where the gas constant used was 0.001986 (kcal / K / mol). When this sample was measured using the above-mentioned test method, the amount of volatile components emitted was 1 ppm by mass, and the amount of main decomposition components emitted was 0 ppm by mass.

[0063] <Model tests of process 2: hydrogenated petroleum resin transfer process and process 3: pelletization process> As a model test to determine the conditions from the end of step 1 to obtaining pellets in step 3, the following operation was carried out. 0.1925 g of the hydrogenated petroleum resin obtained in step 1 was collected in a vial under a nitrogen atmosphere, sealed, and immersed in an oil bath at 200° C. By heating in this state for 40 minutes, the thermal history after the devolatilization step and before the pelletizing treatment was simulated, and thermally decomposed components were generated. The hydrogenated petroleum resin pellets obtained by pelletizing and cooling had an emission amount of 1.5 mass ppm of volatile components and an emission amount of main cracked components of 1.2 mass ppm. It was confirmed that the hydrogenated petroleum resin pellets obtained in Example 1 had an odor at an inconspicuous level. According to this condition, the value of the left term (t × [exp(AE / RT)]) in the formula (1) is 22, and the temperature and time from the end of step 1 to obtaining hydrogenated petroleum resin pellets in step 3 satisfy the formula (1).

[0064] Comparative Example 1 <Model tests of process 2: hydrogenated petroleum resin transfer process and process 3: pelletization process> 0.1924 g of the hydrogenated petroleum resin obtained in step 1 of Example 1 was collected in a vial under a nitrogen atmosphere, sealed, and immersed in an oil bath at 240° C. By heating in this state for 40 minutes, the thermal history after the devolatilization step and before the pelletizing treatment was simulated, and thermally decomposed components were generated. The amount of volatile components emitted from the hydrogenated petroleum resin pellets obtained after cooling was 24.0 ppm by mass, and the amount of main cracked components emitted was 11.2 ppm by mass. According to this condition, the value of the left term (t × [exp(AE / RT)]) in the formula (1) is 821, and the temperature and time from the end of step 1 to obtaining hydrogenated petroleum resin pellets in step 3 do not satisfy the formula (1).

[0065] The results of the examples show that the hydrogenated petroleum resin pellets of the present invention emit less volatile components than conventional pellets, and have an odor that is not noticeable. Furthermore, it is clear that the production method of the present invention can produce hydrogenated petroleum resin pellets with little odor.

Claims

[Claim 1] Hydrogenated petroleum resin pellets having an emission amount of volatile components defined below of 10 mass ppm or less. Amount of volatile components emitted The amount of all components having a retention time shorter than the retention time of normal dodecane as measured by headspace gas chromatography, converted into ethylcyclohexane, relative to the hydrogenated petroleum resin.

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