Chip, method for manufacturing chip, and adhesive composition

Abstract

To provide a chip excellent in anti-blocking property, soluble in an organic solvent in a shorter time, excellent in brush coating property and anti-layer separation property, and capable of obtaining a colorless adhesive composition, a method for producing the chip, and an adhesive composition excellent in brush coating property and anti-layer separation property, and less in coloration.SOLUTION: A chip for an adhesive composition includes a chloroprene polymer rubber, wherein a temperature near the center of the chip after 60 sec. from holding the chip heated to 140°C in a room of 23°C is 130°C or lower, and a time necessary for AX to surpass A0+20 is shorter than 500 min. when a type A durometer hardness measured in accordance with JISK6253-3 after being left for one hour under an environment of 23°C by forming the chip into a sheet of a thickness of 6 mm by press molding at 70°C, and taking out from a metal mold is A0, and a type A durometer hardness measured after X min. from the input by putting a sheet of a thickness of 6 mm into a constant temperature bath of -10°C is AX.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a chip containing a chloroprene-based polymer rubber, a method for producing the chip, and an adhesive composition. [Background technology]

[0002] Chloroprene polymers are materials with excellent heat resistance, weather resistance, ozone resistance, chemical resistance, and flame retardancy (self-extinguishing properties), possessing many superior characteristics compared to natural rubber and other synthetic resins. Because of their well-balanced properties, chloroprene polymers are used in a variety of applications, with adhesive being a prime example.

[0003] Adhesives containing chloroprene polymer rubber are prepared by dissolving chloroprene polymer rubber in an organic solvent such as toluene or acetone, and optionally dissolving and / or dispersing tackifying resins and metal oxides. The adhesive hardens and bonds as the organic solvent evaporates. Because adhesives containing chloroprene polymer rubber have excellent adhesive properties, such as initial bonding strength, they are used in a wide range of fields, including woodworking, furniture making, and automotive applications (see, for example, Patent Documents 1 and 2).

[0004] In recent years, there has been a desire to switch to non-aromatic solvents for solvent-based adhesives. However, this transition has made solvent-based adhesives more susceptible to so-called layer separation, where components that dissolve in organic solvents separate from those that do not, during storage. Regarding technologies relating to compositions containing chloroprene polymers with excellent layer separation stability, Patent Document 3 describes a technique in which specific ethylenically unsaturated sulfonic acids or their salts are copolymerized within a specific range when polymerizing chloroprene. Furthermore, Patent Document 4 discloses a chloroprene rubber composition containing 0.005 to 10 parts by mass of at least one sulfonic acid compound having a specific structure per 100 parts by mass of chloroprene rubber.

[0005] Furthermore, Patent Document 5 discloses an adhesive composition obtained by dissolving in an organic solvent an unmodified chloroprene polymer A, obtained by polymerizing chloroprene alone or copolymerizing two or more monomers containing chloroprene, and a sulfur-modified chloroprene polymer B, obtained by polymerizing chloroprene alone or copolymerizing two or more monomers containing chloroprene in the presence of sulfur. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-226852 [Patent Document 2] Japanese Patent Publication No. 2005-008713 [Patent Document 3] Japanese Patent Publication No. 2007-177198 [Patent Document 4] Japanese Patent Publication No. 2010-275338 [Patent Document 5] Japanese Patent Publication No. 2012-111862 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, conventional chloroprene polymer rubbers have problems: they block when stored under high temperature and pressure, resulting in poor handling properties; and it takes a long time to completely dissolve the chips or sheets containing the chloroprene polymer rubber in an organic solvent to obtain an adhesive composition. Furthermore, there is room for improvement in the layer separation resistance and brush application properties of the obtained adhesive composition, and there is also the problem of the adhesive composition becoming discolored. Solving all of these problems simultaneously has been difficult.

[0008] The present invention has been made in view of these circumstances, and provides a chip that has excellent blocking resistance, dissolves quickly in an organic solvent, has excellent brushability and layer separation resistance, and can produce an adhesive composition that is colorless, a method for producing the chip, and an adhesive composition that has excellent brushability and layer separation resistance and is less colorless. [Means for solving the problem]

[0009] According to the present invention, a tip for an adhesive composition containing a chloroprene polymer rubber, The chip is heated to 140°C, and after being held in a 23°C room for 60 seconds, the temperature near the center of the chip is 130°C or lower. The aforementioned chip is press-molded at 70°C to form a 6mm thick sheet, removed from the mold, left to stand for 1 hour in a 23°C environment, and then the Type A durometer hardness measured according to JIS K 6253-3 is set to A0. The aforementioned 6mm thick sheet is placed in a -10°C constant temperature bath, and the hardness of a Type A durometer after X minutes from placement is measured as A X In that case, A X A chip is provided in which the time required to exceed A0+20 is less than 500 minutes.

[0010] Through diligent research, the inventors have discovered that by highly controlling the manufacturing conditions during the production of chips containing chloroprene polymer rubber, thereby producing chips with low heat accumulation, and by setting the time required for the hardness of the chips measured under specific conditions to change by a specified amount (crystallization time) within a specific range, it is possible to produce chips with excellent blocking resistance, that dissolve quickly in organic solvents, and that also yield adhesive compositions with excellent brushability, layer separation resistance, and minimal discoloration. This has led to the completion of the present invention. Furthermore, according to another aspect of the present invention, a method for manufacturing the chip described above is provided, comprising: a separation step of separating the chloroprene polymer rubber from the chloroprene polymer latex by adding a coagulant to the chloroprene polymer latex containing the chloroprene polymer rubber to obtain a composition containing the chloroprene polymer rubber; and a molding step of molding the composition containing the chloroprene polymer rubber in an extruder to obtain a chip containing the chloroprene polymer rubber, wherein in the molding step, the temperature of the chip containing the chloroprene polymer rubber immediately after extrusion is kept below 150°C. Furthermore, according to another aspect of the present invention, an adhesive composition is provided which comprises a solution obtained by dissolving the chips described above in an organic solvent.

[0011] The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other. (1) A chip for an adhesive composition containing a chloroprene polymer rubber, wherein the chip is heated to 140°C, held in a 23°C room for 60 seconds, and the temperature near the center of the chip is 130°C or lower, the chip is press-molded at 70°C to form a 6mm thick sheet, removed from the mold and left to stand for 1 hour in a 23°C environment, and the Type A durometer hardness measured according to JIS K6253-3 is A0, the 6mm thick sheet is placed in a -10°C constant temperature bath, and the Type A durometer hardness after X minutes from placement is A X In that case, A X A tip that takes less than 500 minutes to exceed A0+20. (2) The chip according to (1), wherein the chip is dissolved in toluene to obtain a toluene solution of 10% by mass of the chloroprene polymer rubber, a glass tube with an inner diameter of 6 mm and an outer diameter of 8 mm is submerged 30 mm in the toluene solution of 10% by mass of the chloroprene polymer rubber adjusted to 20°C, and the glass tube is rotated at 2000 rpm for 30 seconds, the lowest liquid level outside the glass tube is defined as the lowest liquid level outside the glass tube H0, and the highest liquid level inside the glass tube is defined as the highest liquid level inside the glass tube H1, the difference between the lowest liquid level outside the glass tube H0 and the highest liquid level inside the glass tube H1 is 10 mm or less. (3) The chip according to (1) or (2), wherein the absorbance at a wavelength of 440 nm of a toluene solution of 5% by mass of the chloroprene polymer rubber obtained by dissolving the chip in toluene is 0.30 or less. (4) A chip according to any one of items (1) to (3), wherein when 100 g of the chip is dissolved in 400 g of an organic solvent having a cyclohexane:ethyl acetate = 1:1 (mass ratio) at 23°C, the time until the chip dissolves in the organic solvent is 300 minutes or less. (5) The chip according to any one of items (1) to (4), wherein the total content of alkaline earth metals, magnesium, aluminum, and zinc in the chip is 1 to 5000 mg / kg. A method for manufacturing a chip according to any one of (6)(1) to (5), comprising: a separation step of separating the chloroprene polymer rubber from the chloroprene polymer latex by adding a coagulant to the chloroprene polymer latex containing the chloroprene polymer rubber to obtain a composition containing the chloroprene polymer rubber; and a molding step of molding the composition containing the chloroprene polymer rubber in an extruder to obtain a chip containing the chloroprene polymer rubber, wherein in the molding step, the temperature of the chip containing the chloroprene polymer rubber immediately after extrusion is less than 150°C. (7)(6) A manufacturing method according to the above, wherein in the molding step, the temperature of the chip containing the chloroprene polymer rubber 60 seconds after extrusion is 130°C or lower. The production method according to (8), (6) or (7), wherein in the molding step, the temperature of the die head is set to 120° C. or lower, and the ratio Y / Z of the discharge rate Y (mm / min) of the chloroprene-based polymer rubber in the die head to the rotational speed Z (rpm) of the cutting blade for cutting the discharged chloroprene-based polymer rubber is set to 1 to 10. The production method according to any one of (9), (6) to (8), which does not include a step of water-cooling the chip after the molding step. The production method according to any one of (10), (6) to (9), further including a drying step of removing water from the composition containing the chloroprene-based polymer rubber separated in the separation step, wherein the atmospheric temperature in the drying step is set to 130° C. or lower. The production method according to (11), (10), wherein the separation step, the drying step, and the molding step are performed in an extruder. An adhesive composition containing a solution in which the chip according to any one of (1) to (5) is dissolved in an organic solvent. [[Effect of the Invention]]

[0012] According to the chip of the present invention, by making the chip have less heat storage and setting the time (crystallization time) required for the hardness of the chip measured under specific conditions to change by a specified amount within a specific range, the chip has excellent blocking resistance and can be dissolved in an organic solvent in a short time. Further, according to the chip, an adhesive composition excellent in brush coating property, layer separation resistance, and having little coloring can be obtained. [[Brief Description of the Drawings]]

[0013] [Figure 1] It is a schematic diagram for explaining a method of measuring the liquid level height in a glass tube during stirring of a toluene solution. [[Embodiments for Carrying Out the Invention]]

[0014] The present invention will be described in detail below with reference to embodiments of the present invention. The present invention is not limited in any way by these descriptions. The various features of the embodiments of the present invention shown below can be combined with each other. Furthermore, each feature constitutes an invention independently.

[0015] 1. Chloroprene-based polymer rubber The chip according to the present invention contains a chloroprene-based polymer rubber. Furthermore, the chloroprene-based polymer rubber according to the present invention contains a chloroprene-based polymer. The chloroprene-based polymer is a homopolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene), or a copolymer of a chloroprene monomer and another monomer copolymerizable thereto.

[0016] Examples of monomers copolymerizable with chloroprene monomers include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid or its esters, methacrylic acid or its esters, etc. These may be used alone or in combination of two or more. While not particularly limited, from the viewpoint of maintaining properties derived from chloroprene and adjusting the crystallinity of the polymer and setting the crystallization time within a specific range, the chloroprene-based polymer according to one embodiment of the present invention preferably contains 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, monomer units derived from chloroprene monomers when the chloroprene-based polymer is considered as 100% by mass.

[0017] 2. Chips containing chloroprene-based polymer rubber The chip according to the present invention contains a chloroprene-based polymer rubber. The chip according to the present invention has heat storage properties and crystallization time within a specific range.

[0018] <Heat storage> The chip according to the present invention has a temperature near the center of the chip after 60 seconds of being held in a 23°C room after being heated to 140°C, which is 130°C or lower. The chip according to the present invention has a temperature near the center of the chip after 60 seconds of being held in a 23°C room after being heated to 140°C, which is, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130°C, and may be within the range of any two of the values ​​exemplified here.

[0019] Here, the temperature near the center of a chip heated to 140°C can be measured after 60 seconds in a 23°C room using the following procedure. First, insert a K-type thermocouple into the chip so that its tip is near the center of the chip. Then, place the chip in an oven set to 150°C and heat it until the temperature near the center reaches 140°C. After the temperature near the center of the chip reaches 140°C, remove the chip and measure the temperature near the center of the chip over time. During this time, it is preferable to keep the chip suspended in the air so that its surface does not come into contact with other objects. The temperature near the center of the chip 60 seconds after being removed to a 23°C environment is defined as "the temperature near the center of the chip 60 seconds after being heated to 140°C and held in a 23°C room." Preferably, the tip of the thermocouple is inserted into the chip at a point closer to the center of the chip than to the chip surface, i.e., into the chip itself. The distance between the tip of the thermocouple and a plane perpendicular to the thickness direction that passes through the midpoint of the thickness is preferably 40% or less of the thickness, preferably 30% or less, and preferably 20% or less. The distance between the tip of the thermocouple and the plane parallel to the thickness direction including the minor axis is preferably 30% or less of the major axis, preferably 20% or less, and preferably 10% or less. The distance between the tip of the thermocouple and the plane parallel to the thickness direction including the major axis is preferably 30% or less of the minor axis, preferably 20% or less, and preferably 10% or less.

[0020] The above temperature can be adjusted by precisely controlling the chip manufacturing conditions, particularly the type and amount of compound used in the production of chloroprene polymer latex, as well as the chip molding conditions, thereby controlling the chip's composition, specific heat, specific surface area, shape, etc.

[0021] <Crystallization time> The chip according to the present invention is formed into a 6 mm thick sheet by press molding at 70°C, removed from the mold and left to stand for 1 hour in a 23°C environment, and the Type A durometer hardness measured according to JIS K 6253-3 is set to A0. The 6 mm thick sheet is placed in a -10°C constant temperature bath, and the Type A durometer hardness after X minutes from the time of placement is set to A X In that case, A X The time required for it to exceed A0+20 is less than 500 minutes. In this specification, the above "A X The time required for the value to exceed A0+20 is also called the crystallization time. The chip according to the present invention has a crystallization time of, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500 minutes, or within the range of any two of the values ​​exemplified here.

[0022] Here, the crystallization time can be measured using the following procedure. (Preparation of sheets for hardness measurement) First, a sheet for hardness measurement is prepared. For example, the sheet can be prepared using the following procedure. Process the chip into a sheet shape with a thickness of 3 mm using an 8-inch diameter roll (surface temperature 30°C). Stack three of these sheets in a mold with a depth of 6 mm × length of 130 mm × width of 25 mm such that the longitudinal direction is the column arrangement direction of the roll (the direction along the roll circumference when processed into a sheet shape by the roll), and press at 70°C for 20 minutes. It is preferable to leave the sample taken out from the mold to stand in a 23°C environment for 1 hour. Also, it is preferable to measure A0 described below immediately after the 1-hour standing. A0 is more preferably measured within 1 hour and preferably within 30 minutes after the end of at least 1-hour standing time.

[0023] (Measurement of hardness before input into -10°C environment) For the sheet after standing, measure the hardness using a Type A durometer based on JIS K 6253-3, and define the Type A durometer hardness at this time as A0. A0 indicates the hardness before input into the -10°C environment.

[0024] (Calculation of time required for hardness to exceed A0 + 20 at -10°C (crystallization time)) Subsequently, determine the time required for the hardness to exceed A0 + 20. Specifically, put the sample into a -10°C low-temperature constant temperature bath, and measure the hardness using a Type A durometer in the low-temperature constant temperature bath at regular intervals. The sample is preferably put into the -10°C low-temperature constant temperature bath within 1 hour and more preferably within 30 minutes after the end of the above 1-hour standing time. Here, let the Type A durometer hardness X minutes after input be A X and find the time required for A X to exceed A0 + 20. The time required for A X to exceed A0 + 20 is defined as the crystallization time. Note that the hardness measurement using the durometer is preferably performed three times with the measurement locations shifted, and the average value of the instantaneous values is recorded. Here, the instantaneous value indicates the hardness value at the moment when the needle of the durometer is pressed against the sample.

[0025] The crystallization time can be adjusted by controlling the chip manufacturing conditions, the type and amount of compound used in the production of the chloroprene polymer latex, particularly the type and amount of monomer used in polymerization, the polymerization conditions, and the thermal history throughout the entire process, thereby controlling the degree of branching of the polymer in the final chip. According to conventional technology, it has been difficult to obtain a chip that excels in all of the following properties: blocking properties, brushability, and coloring, which worsen as the thermal history and degree of polymer branching increase, and layer separation resistance, which improves as the degree of polymer branching increases. However, according to the present invention, by appropriately controlling the heat storage capacity and crystallization time, it is possible to obtain a chip that has excellent blocking resistance, dissolves quickly in organic solvents, and is a colorless adhesive composition with excellent brushability and layer separation resistance.

[0026] <shape> The chip according to one embodiment of the present invention is preferably in the shape of a scale. The chip according to one embodiment of the present invention is preferably 10 mm or less in thickness, and preferably 7 mm or less. The thickness may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 mm, or within the range of any two of the values ​​exemplified herein. The chip according to one embodiment of the present invention preferably has a major diameter of 50 mm or less, and more preferably 45 mm or less. The major diameter may be, for example, 10, 15, 20, 25, 30, 35, 40, 45, or 50 mm, and may be within the range of any two of the values ​​exemplified here. The chip according to one embodiment of the present invention preferably has a short diameter of 22 mm or less, and more preferably 20 mm or less. The short diameter may be, for example, 10, 12, 14, 16, 18, 20, or 22 mm, and may be within the range of any two of the values ​​exemplified herein. Furthermore, the minor axis can be defined as the maximum length in the direction perpendicular to the major axis. By adopting the above shape, it is easier to obtain a chip with the heat retention properties described above. The shape of the chip can be adjusted by appropriately controlling the chip manufacturing conditions, particularly the die shape during chip forming, the number and rotation speed of the cutting blades, the discharge speed, the die head temperature, and the ratio of discharge speed to the cutting blade rotation speed.

[0027] <Liquid level inside the glass tube when stirring toluene solution (brush application)> A chip according to one embodiment of the present invention is prepared by dissolving the chip in toluene to make a toluene solution of 10% by mass of chloroprene polymer rubber, and then immersing a glass tube with an inner diameter of 6 mm and an outer diameter of 8 mm in the toluene solution of 10% by mass of chloroprene polymer rubber, which has been adjusted to 20°C, to a depth of 30 mm, and rotating the glass tube at 2000 rpm for 30 seconds. The lowest liquid level outside the glass tube is defined as the lowest liquid level outside the glass tube, H0. When the highest liquid level inside the glass tube is defined as the highest liquid level H1 inside the glass tube, It is preferable that the difference between the lowest liquid level height H0 outside the glass tube and the highest liquid level height H1 inside the glass tube is 10 mm or less. As shown in Figure 1, when a glass tube submerged in a toluene solution is rotated, the liquid levels inside and around the glass tube rise, while the liquid level outside the glass tube, away from the tube, drops slightly compared to when it is not rotating. In this specification, the liquid level inside the glass tube when it is rotated at 2000 rpm for 30 seconds is defined as H1, and the lowest liquid level outside the glass tube is defined as the lowest liquid level outside the glass tube, H0. In this specification, the "difference between the lowest liquid level H0 outside the glass tube and the highest liquid level H1 inside the glass tube" during the rotation of the glass tube is also referred to as the "liquid level inside the glass tube during stirring of the toluene solution." Specifically, the liquid level inside the glass tube during stirring of the toluene solution is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mm, and may be within the range of any two of the values ​​exemplified here. The liquid level inside the glass tube during stirring of the toluene solution can be specifically evaluated by the method described in the examples. The liquid level inside the glass tube during stirring of a toluene solution is thought to be related to the structure of the chloroprene polymer contained in the chip, specifically the amount of linear polymer and branched polymer. It is believed that a lower degree of branching of the polymer results in a lower liquid level inside the glass tube during stirring of the toluene solution. The liquid level inside the glass tube during stirring of the toluene solution can be adjusted by controlling the manufacturing conditions of the chip, particularly the polymerization temperature and degree of polymerization, as well as appropriately controlling the thermal history of the chloroprene polymer in the chloroprene polymer latex manufacturing process and the chip manufacturing process, and the heat storage capacity of the chip. For example, lowering the polymerization temperature and degree of polymerization reduces the degree of branching of the polymer, which tends to result in a lower liquid level inside the glass tube during stirring of the toluene solution. The phenomenon of the liquid level rising in a toluene solution is due to the Weisenberg effect, and the higher the liquid level in the glass tube when stirring the toluene solution, the worse the brush application becomes. Poor brush application means that the viscosity of the adhesive is high, causing it to become wavy during application and making it impossible to apply it with a uniform thickness. By keeping the liquid level inside the glass tube below the above value when stirring the toluene solution, the brush application properties are further improved.

[0028] <Yellowness> In one embodiment of the present invention, the tip is preferably such that the absorbance at a wavelength of 440 nm of a toluene solution containing 5% by mass of chloroprene polymer rubber, obtained by dissolving the tip in toluene, is 0.30 or less. Specifically, the absorbance may be, for example, 0.01, 0.03, 0.05, 0.10, 0.15, 0.20, 0.25, or 0.30, and may be within the range of any two of the values ​​exemplified here. The absorbance described above can be evaluated specifically by the method described in the examples. The absorbance mentioned above is thought to be related to the amount of conjugated double bonds in the chloroprene polymer rubber, and can be adjusted by appropriately controlling the chip manufacturing conditions, particularly the thermal history of the chloroprene polymer in the chloroprene polymer latex manufacturing process and the chip manufacturing process, as well as the heat storage capacity of the chip.

[0029] <Solubility in organic solvents> In one embodiment of the present invention, when 100 g of the chip is dissolved in 400 g of an organic solvent containing cyclohexane and ethyl acetate in a mass ratio of 1:1 at 23°C, it is preferable that the time it takes for the chip to dissolve in the organic solvent is 300 minutes or less. Specifically, the above dissolution time is, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 minutes, and may be within the range of any two of the values ​​exemplified here. The above dissolution time can be specifically evaluated by the method described in the examples. The above dissolution time can be adjusted by precisely controlling the chip manufacturing conditions, particularly the type and amount of compound used in the production of chloroprene polymer latex, as well as the chip molding conditions, thereby controlling the chip's components, specific surface area, shape, etc. Because the chip according to one embodiment of the present invention has excellent solubility in organic solvents, adhesive compositions and the like can be manufactured in a short time, thereby improving productivity.

[0030] <Total content of alkaline earth metals, magnesium, aluminum, and zinc> In one embodiment of the present invention, the chip preferably has a total content of alkaline earth metals, magnesium, aluminum, and zinc of 1 to 5000 mg / kg. Specifically, the total content of alkaline earth metals, magnesium, aluminum, and zinc may be, for example, 1, 10, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000 mg / kg, and may be within the range of any two of the values ​​exemplified here. The content of alkaline earth metals, magnesium, aluminum, and zinc can be measured, for example, by inductively coupled plasma atomic emission spectroscopy (ICP-OES). Specifically, first, the chip is cut into pieces smaller than 5 mm square with scissors. 0.5 g of the cut sample is weighed out, 8 mL of nitric acid is added, and the sample is decomposed and dissolved using a microwave decomposition device. After cooling the resulting decomposition solution, it is diluted to a final volume of 25 mL and measured using an inductively coupled plasma atomic emission spectroscopy device. The content of alkaline earth metals, magnesium, aluminum, and zinc can be adjusted by controlling the manufacturing conditions of the chips, particularly the type and amount of coagulant used during the solidification of the chloroprene polymer rubber.

[0031] The above-mentioned tips can be suitably used for adhesive compositions. Because the tips exhibit excellent blocking resistance, they are less prone to sticking together, resulting in good handling during the manufacture of adhesive compositions. Furthermore, they dissolve quickly in organic solvents, allowing for the rapid production of adhesive compositions. The resulting adhesive compositions also exhibit excellent brushability, resistance to layer separation, and minimal discoloration.

[0032] 3. Method for manufacturing chips containing chloroprene polymer rubber The method for producing chips containing chloroprene-based polymer rubber according to the present invention is not particularly limited. A manufacturing method according to one embodiment of the present invention is: A separation step to obtain a composition containing chloroprene polymer rubber by adding a coagulant to chloroprene polymer latex containing chloroprene polymer rubber, thereby separating the chloroprene polymer rubber from the chloroprene polymer latex. A molding process to obtain chips containing chloroprene polymer rubber by molding a composition containing chloroprene polymer rubber in an extruder. It can be equipped with. Furthermore, the manufacturing method according to one embodiment of the present invention further includes the following steps before the separation step: Emulsion polymerization process to obtain chloroprene polymer latex containing chloroprene polymer rubber by emulsion polymerization of monomers containing chloroprene monomers. It can be equipped with.

[0033] 3.1 Emulsion polymerization process In the emulsion polymerization process according to one embodiment of the present invention, a chloroprene monomer, or a chloroprene monomer and other monomers copolymerizable therewith, is emulsion polymerized using emulsifiers, dispersants, polymerization initiators, chain transfer agents, etc. as appropriate, and a polymerization inhibitor is added when the desired polymerization rate is reached to obtain a chloroprene polymer latex. Furthermore, unreacted monomers can be removed from the chloroprene polymer latex obtained in this way by methods such as steam flashing or concentration.

[0034] <Emulsifiers and dispersants> The emulsifier is not particularly limited, and known anionic, nonionic, or cationic emulsifiers used in the polymerization of chloroprene polymers can be used. Anionic emulsifiers include carboxylic acid type, sulfonic acid type, and sulfate ester type, and examples include higher fatty acid salts, alkenyl succinates, alkali metal salts of rosinic acid, alkyl sulfonates with 8 to 20 carbon atoms, alkylaryl sulfates, and condensates of sodium naphthalene sulfonate and formaldehyde. Examples of nonionic emulsifiers include polyvinyl alcohol or its copolymers (e.g., copolymers with acrylamide), polyvinyl ether or its copolymers (e.g., copolymers with maleic acid), polyvinylpyrrolidone or its copolymers (e.g., copolymers with vinyl acetate), or chemically modified versions of these (co)polymers, or cellulose derivatives (hydroxyethylcellulose), etc. Cationic emulsifiers include aliphatic amine salts and aliphatic quaternary ammonium salts, such as octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, and dilauryldimethylammonium chloride. Among these, the emulsifier preferably contains rosin acid or an alkali metal salt of rosin acid. These may be used individually or in combination of two or more. The amount of the emulsifier can be 2.0 to 7.5 parts by mass with respect to 100 parts by mass of the monomer.

[0035] <pH adjuster> The raw materials added to the polymerization system at the start of polymerization can include a pH adjuster. Examples of the pH adjuster include potassium pyrosulfite, potassium sulfite, potassium bisulfite, potassium phosphate, dipotassium hydrogen phosphate, sodium pyrosulfite, sodium sulfite, sodium bisulfite, sodium phosphate, disodium hydrogen phosphate, potassium hydroxide, sodium hydroxide, and the like. The pH adjuster may be used alone or in combination of two or more thereof. Among these pH adjusters, it is preferable to use potassium hydroxide or sodium hydroxide because they have a high effect of increasing the pH value. The addition amount of the pH adjuster can be 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the monomer.

[0036] <Polymerization initiator> The raw materials added to the polymerization system at the start of polymerization can include a polymerization initiator. Examples of the polymerization initiator include potassium persulfate, benzoyl peroxide, ammonium persulfate, hydrogen peroxide, etc., which are usually used in radical polymerization. The addition amount of the polymerization initiator can be 0.001 to 1 part by mass with respect to 100 parts by mass of the monomer.

[0037] <Chain transfer agent> There is no particular limitation on the chain transfer agent as long as it is generally used in the production of chloroprene polymers. For example, long-chain alkyl mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, and n-octyl mercaptan, dialkyl xanthogen disulfides such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide, and known chain transfer agents such as iodoform can be used. The addition amount of the chain transfer agent can be 0.001 to 10 parts by mass with respect to 100 parts by mass of the total monomers.

[0038] <Polymerization temperature> The polymerization temperature is preferably in the range of 0 to 55°C from the viewpoint of ease of controlling the reaction. From the viewpoint of carrying out the polymerization reaction more smoothly and safely, it is desirable to set the lower limit of the polymerization temperature to 5°C or higher and the upper limit to 45°C or lower, more preferably to less than 40°C, and even more preferably to 35°C or lower. By adjusting the polymerization temperature, the degree of branching of the resulting chloroprene-based polymer rubber can be adjusted, and the crystallization time of the resulting chips can be controlled.

[0039] <Polymerization rate> In the emulsion polymerization process, polymerization can be stopped by adding a polymerization inhibitor when the monomer reaches the desired polymerization rate, thereby obtaining a polymerization solution where the reaction is complete. The polymerization rate at the end of polymerization can be less than 100%, and can be in the range of 60-95%.

[0040] <Polymerization inhibitor> Examples of polymerization inhibitors that can be used include thiodiphenylamine, 4-tert-butylcatechol, and 2,2'-methylenebis-4-methyl-6-tert-butylphenol.

[0041] <Removal of unreacted monomers> After polymerization is complete, unreacted monomers remaining after emulsion polymerization can be removed from the polymerization solution by conventional methods such as steam stripping or reduced-pressure heating evaporation to obtain a chloroprene-based polymer latex.

[0042] 3.2 Separation process A manufacturing method according to one embodiment of the present invention may include a separation step in which a coagulant is added to a chloroprene polymer latex containing chloroprene polymer rubber obtained in an emulsion polymerization step, thereby separating the chloroprene polymer rubber from the chloroprene polymer latex and obtaining a composition containing chloroprene polymer rubber.

[0043] In the separation step, it is preferable to separate the chloroprene polymer rubber by adding a coagulant to the chloroprene polymer latex obtained in the emulsion polymerization step. Generally, a method of separating chloroprene polymer rubber from chloroprene polymer latex is used, which involves emulsion destruction using a freeze roll. However, this method has the problem of poor energy efficiency. Furthermore, the freeze roll method is often carried out in an open system, resulting in a poor working environment. In the manufacturing method according to one embodiment of the present invention, the energy efficiency of the process can be improved by separating the chloroprene polymer rubber using a coagulant without using a freeze roll. In addition, in the manufacturing method according to one embodiment of the present invention, the separation step can be carried out in an extruder, more preferably the separation step and the drying step can be carried out in an extruder, and even more preferably the separation step, the drying step and the molding step can be carried out in an extruder, thereby improving the working environment. Note that carrying out the molding step in an extruder includes cases where a part of the molding step is carried out in an extruder.

[0044] The coagulant is preferably an aqueous solution containing at least one of the group consisting of alkaline earth metal salts, magnesium salts, aluminum salts, and zinc salts, and more preferably an aqueous solution containing at least one of the chlorides, sulfates, nitrates, and phosphates of calcium, magnesium, aluminum, and zinc. Among these, the coagulant is more preferably an aqueous solution containing at least one of the group consisting of calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, and aluminum sulfate. The coagulant is preferably added in such a way that the total amount of alkaline earth metal salts, magnesium salts, aluminum salts, and zinc salts is 0.05 to 10 parts by mass per 100 parts by mass of chloroprene polymer latex. By keeping the total amount of alkaline earth metal salts, magnesium salts, aluminum salts, and zinc salts above the above lower limit, sufficient coagulation can be achieved, and a sufficient recovery rate can be obtained. Furthermore, by keeping the total amount of alkaline earth metal salts, magnesium salts, aluminum salts, and zinc salts below the above lower limit, manufacturing costs can be reduced.

[0045] Chloroprene polymer latex and coagulant can be mixed in an extruder using a screw. The mixing conditions should be adjusted as appropriate to ensure that the chloroprene polymer latex and coagulant are thoroughly mixed. For example, the screw outer diameter can be 20 to 120 mm, specifically 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120 mm, and may also be within the range of any two of the values ​​exemplified here. The ratio of screw length (L) to diameter (D), L / D, can be between 40 and 80. Specifically, for example, it could be 40, 45, 50, 55, 60, 65, 70, 75, or 80, and may also be within the range of any two of the values ​​exemplified here. The screw rotation speed can be 30 to 160 rpm, specifically, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160 rpm, and may also be within the range of any two of the values ​​exemplified here. When the supply amount of chloroprene polymer latex is 100 parts by mass / hour, the supply amount of coagulant can be 10 to 200 parts by mass / hour, specifically, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200 parts by mass / hour, and may be within the range of any two of the values ​​exemplified here. By setting each of the above conditions within the specified numerical range, shear heat generated by the screw can be suppressed, preventing deterioration of the chloroprene polymer rubber. This makes it easier to obtain a tip that has superior blocking resistance, excellent brushability and layer separation resistance, and is free of color. Furthermore, by setting each of the above conditions within the specified numerical range, the chloroprene polymer latex and the coagulant are mixed more thoroughly, and the chloroprene polymer rubber can be separated more efficiently.

[0046] The solidified chloroprene polymer rubber is separated from the suspension containing the solidified material and then, preferably, dewatered in a dewatering device to obtain a composition containing the chloroprene polymer rubber. Examples of dewatering devices include known dewatering devices such as slits, strainers, or dewatering rolls.

[0047] A manufacturing method according to one embodiment of the present invention may further include a drying step to remove water from the composition containing the chloroprene polymer rubber separated in the separation step. In the drying process, it is preferable to keep the ambient temperature below 130°C. Specifically, the temperature in the drying process may be, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, or 130°C, and may be within the range of any two of the values ​​exemplified here. The drying process is preferably limited to 10 minutes or less. The drying process preferably includes a high-temperature drying step in which the material is heated to 100°C or higher, and a low-temperature drying step in which the material is heated to below 100°C. In the high-temperature drying process, the ambient temperature can be, for example, 100, 110, 120, or 130°C, and may be within the range of any two of the values ​​exemplified here. The high-temperature drying process is preferably no more than 3 minutes. In the low-temperature drying process, the ambient temperature is specifically, for example, 30, 40, 50, 60, 70, 80, 90, or 100°C, and may be within the range of any two of the values ​​exemplified here. The low-temperature drying process is preferably 7 minutes or less. In one embodiment of the present invention, the drying process preferably includes a low-temperature drying process after a high-temperature drying process. By including a low-temperature drying process after the high-temperature drying process, the first half, in which a large amount of water remains and is affected by the cooling effect of latent heat, can be dried at a high temperature, and the second half, in which there is less water and the effect of the cooling effect of latent heat is less pronounced, can be dried at a low temperature, thereby suppressing thermal changes in the chips.

[0048] 3.3 Molding process A manufacturing method according to one embodiment of the present invention may include a molding step of molding a composition containing chloroprene polymer rubber in an extruder to obtain chips containing chloroprene polymer rubber. The molding step can be performed using, for example, a side hot cut method, a center hot cut method, or the like.

[0049] In the molding process, it is preferable that the temperature of the chip containing the chloroprene polymer rubber immediately after extrusion be kept below 150°C. The temperature immediately after extrusion may be, for example, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, or 150°C, and may be within the range of any two of the values ​​exemplified here. The temperature of the tip containing chloroprene polymer rubber 60 seconds after dispensing is preferably 130°C or lower. The temperature 60 seconds after dispensing may be, for example, 50, 60, 70, 80, 90, 100, 110, 120, or 130°C, and may be within the range of any two of the values ​​exemplified here. Here, the temperature of the tip containing chloroprene polymer rubber immediately after dispensing and the temperature 60 seconds after dispensing can be determined using a contact thermometer. By keeping the temperature immediately after dispensing and the temperature 60 seconds after dispensing below the above upper limit, it is possible to suppress changes in the properties of the chloroprene polymer rubber due to heat, and obtain a tip that is more likely to have excellent brushability, layer separation resistance, and be a colorless adhesive composition. The temperature immediately after dispensing and the temperature 60 seconds after dispensing can be controlled by adjusting conditions in the molding process such as die head temperature, dispensing volume, number of cutting blades and rotation speed, and die shape.

[0050] In the molding process according to one embodiment of the present invention, it is preferable to set the die head temperature to 120°C or lower. The die head temperature may be, for example, 100, 105, 110, 115, or 120°C, and may be within the range of any two of the values ​​exemplified herein. As an example, in the molding process according to one embodiment of the present invention, the discharge rate of the composition containing chloroprene polymer rubber can be 15 to 35 kg / h, specifically, for example, 15, 20, 25, 30, or 35 kg / h, and may be within the range of any two of the values ​​exemplified here. As an example, in the molding process according to one embodiment of the present invention, the discharge speed of the composition containing chloroprene polymer rubber can be set to 1200 to 2800 mm / min. Specifically, for example, this could be 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, or 2800 mm / min, and it may also be within the range of any two of the values ​​exemplified here. Furthermore, as an example, in the molding process according to one embodiment of the present invention, the shape of the die can be set to a diameter of 5 to 25 mm, specifically, for example, 5, 10, 15, 20, 25 mm, and may be within the range of any two of the values ​​exemplified here. The die can have 1 to 5 holes. For example, the die may have 1, 2, 3, 4, and 5 holes, and may also be within a range of any two of the numbers exemplified here. Furthermore, as an example, in the molding process according to one embodiment of the present invention, the number of cutting blades can be reduced to one. The cutting blade rotation speed can be 200 to 1000 rpm, specifically, for example, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 rpm, and may also be within the range of any two of the values ​​exemplified here. The ratio (Y / Z) of the discharge speed Y (mm / min) of the chloroprene polymer rubber in the die head to the rotational speed Z (rpm) of the cutting blade that cuts the discharged chloroprene polymer rubber is preferably between 1 and 10. Specifically, Y / Z may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or within the range of any two of the values ​​exemplified here. For example, by setting each of the above conditions within the above numerical range, the chip is more likely to have the desired thickness, and heat generation due to pressure loss in the die portion is more easily suppressed. By setting each of the above conditions within the above numerical ranges, the temperature and heat retention of the tip after dispensing can be controlled more appropriately, making it easier to obtain a tip that has superior blocking resistance, brush application properties, layer separation resistance, and is free of coloring from the adhesive composition.

[0051] In a manufacturing method according to one embodiment of the present invention, it is preferable that the process does not include a step of water-cooling the chip after the molding process. Although it is possible to rapidly cool the chip by including a step of water-cooling the chip, in that case, it is necessary to include a step of removing the water, which may subject the chip to a longer thermal history, and is also undesirable from the viewpoint of energy efficiency. Because the chip according to one embodiment of the present invention has sufficiently low heat retention, the deterioration of the chloroprene polymer rubber can be sufficiently suppressed even without a step of water cooling the chip after the molding process.

[0052] 4. Adhesive composition An adhesive composition according to one embodiment of the present invention comprises a solution obtained by dissolving the above-mentioned chip in an organic solvent. Because the above-mentioned chip contains a chloroprene-based polymer rubber whose deterioration due to heat is suppressed, the resulting adhesive composition has excellent brushability, resistance to layer separation, and minimal discoloration.

[0053] The type of organic solvent mentioned above is not limited; for example, organic solvents such as toluene, xylene, acetone, methyl ethyl ketone, n-hexane, cyclohexane, methylcyclohexane, cyclopentane, isopropyl acetate, and ethyl acetate can be used. The organic solvent can be a non-aromatic solvent such as n-hexane, cyclohexane, methylcyclohexane, acetone, methyl ethyl ketone, ethyl acetate, or butyl acetate, rather than an aromatic solvent such as toluene, xylene, or ethylbenzene, which are substances that cause sick building syndrome. It is more preferable to dissolve the chloroprene polymer rubber using only a mixture of poor solvents that have poor solubility for chloroprene polymer rubber on their own. For example, an organic solvent in a cyclohexane:ethyl acetate ratio of 1:1 (by mass) can be used.

[0054] The amount of organic solvent used can be adjusted as appropriate depending on the application and type of adhesive, and is not particularly limited. However, it is preferable to adjust the viscosity of the adhesive composition to 3500-4500 mPa·S, as this provides a good balance between the heat resistance and initial adhesive strength of the adhesive.

[0055] The adhesive composition may contain, in addition to the solvent, a metal oxide, a tackifying resin, and an anti-aging agent. By adding these additives to the adhesive composition, the initial adhesive strength, normal adhesive strength, and spray coating properties of the resulting adhesive composition can be improved.

[0056] Examples of metal oxides that can be used include zinc oxide (zinc oxide), aluminum oxide, titanium oxide, and magnesium oxide. Examples of tackifying resins that can be used include phenolic resins, rosin resins, coumarone resins, and petroleum resins. Examples of anti-aging agents include 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,6-di-t-butyl-4-methylphenol, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and N,N'-hexane-1,6-diylbis-3-(3,5-di-t-butyl-4-hydroxyphenyl Possible alternatives include lopionamide, 3,5-bis(1,1-dimethylethyl)-4-hydroxyalkyl ester, diethyl[{3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl}methyl]phosphonate, 3,3',3'',5,5',5''-hexa-t-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, ethylenebis(oxyethylene)bis[3-(5-t-butyl-4-hydroxy-m-tolyl)propyl], tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, tetramethyl thiuram monosulfide, dibutylhydroxytoluene, etc.

[0057] The adhesive composition may further contain formaldehyde catchers, fillers, and the like, depending on the desired physical properties.

[0058] Examples of formaldehyde catchers that can be used include pyrrolidine, piperidine, piperazine, morpholine, melamine, dicyandiamide, urea, ethyleneurea, 4,5-dimethoxyethyleneurea, propyleneurea, 5-methylpropyleneurea, 5-hydroxypropyleneurea, 5-methoxypropyleneurea, oxalylurea (parabanic acid), hydrazobenzothiazole, semicarbazide, and thiosemicarbazide. Formaldehyde catchers can capture formaldehyde, a harmful volatile substance. As fillers, talc, calcium carbonate, clay, smectite, silica, hydrotalcite, mica, etc., can be used.

[0059] Furthermore, to improve light resistance, ultraviolet absorbers such as benzotriazole and light stabilizers such as hindered amines may be added to the adhesive composition.

[0060] An adhesive composition according to one embodiment of the present invention may also contain at least one raw rubber (uncrosslinked or unvulcanized rubber) selected from the group consisting of natural rubber, isoprene rubber, butyl rubber, nitrile rubber, hydrogenated nitrile rubber, butadiene rubber, styrene-butadiene rubber, and ethylene propylene rubber.

[0061] The method for producing the adhesive composition is not particularly limited, and known machines and equipment may be used. Generally, a method can be employed in which alkylphenol resin or magnesium oxide is dissolved in an organic solvent, and after standing at room temperature for 10 to 20 hours, chips containing chloroprene polymer rubber, metal oxides, antioxidants, etc. are dissolved.

[0062] The adhesive composition according to one embodiment of the present invention can be used as an adhesive or a raw material for an adhesive. For example, an adhesive can be obtained by adding other additives to the adhesive composition or by mixing the adhesive composition with another adhesive composition. The adhesive can be suitably used for joining and bonding similar or different materials such as paper, wood, cloth, leather, jersey, rubber, plastic, foam, ceramics, glass, mortar, cement-based materials, and metals.

[0063] The adhesive composition according to one embodiment of the present invention preferably does not exhibit layer separation even after more than 6 weeks when stored in a glass container in a constant temperature bath at 60°C under light shielding after preparation, and more preferably does not exhibit layer separation even after more than 7 weeks. [Examples]

[0064] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0065] (Example 1) <Manufacturing of chloroprene polymer latex> In a reactor with an internal volume of 5 liters, under a nitrogen atmosphere, 3.3 parts by mass of disproportionated sodium gum rosinate 3R-70N (manufactured by Arakawa Chemical Industries, Ltd.), 0.5 parts by mass of disproportionated sodium tol rosinate 6R-70N (manufactured by Harima Chemicals, Ltd.), 0.4 parts by mass of sodium salt of naphthalene sulfonic acid and formaldehyde condensate (trade name Demol N: manufactured by Kao Corporation), 0.5 parts by mass of sodium bisulfite, 0.0003 parts by mass of thiourea dioxide, and 0.3 parts by mass of sodium hydroxide were dissolved in 110 parts by mass of pure water. To this solution, 100 parts by mass of chloroprene monomer and 0.15 parts by mass of n-dodecyl mercaptan were added and emulsified, and then potassium persulfate was added as a polymerization initiator, and polymerization was carried out at a polymerization temperature of 10°C under a nitrogen atmosphere. When the polymerization conversion rate reached 72% or more, phenothiazine emulsion was added as a polymerization termination agent to stop the reaction. Unreacted monomers were removed under reduced pressure to obtain chloroprene-based polymer latex 1 with a solid content of 40%.

[0066] <Manufacturing of chips containing chloroprene polymer rubber> We manufactured chips containing chloroprene polymer rubber from chloroprene polymer latex. The obtained chloroprene polymer latex 1 and a coagulant (1% calcium chloride, 0.6% acetic acid aqueous solution) were supplied to a twin-screw extruder and mixed with a screw to solidify the chloroprene polymer latex. The resulting solidified body was then dehydrated, washed, and dried to obtain chloroprene polymer rubber, which was then chipped by a side hot-cut molding process. The above solidification, dehydration, washing, drying, and molding (extrusion into a rod shape) processes were carried out inside the twin-screw extruder.

[0067] The manufacturing conditions for the above process are shown below. Equipment: Twin-screw extruder (screw outer diameter: φ47mm, L / D: 59.5) Die shape (Φ15mm x 1 hole) Number of cutting blades: 1 Condition: Screw rotation speed: 85 rpm Latex supply rate: 75 kg / h Coagulant supply rate: 50 kg / h Drying process temperature: First half: 120°C x 2 minutes, Second half: 60°C x 3 minutes Die head temperature: 110℃ Rubber discharge rate: 26 kg / h Discharge speed: 2130mm / min Cutting blade rotation speed: 600 rpm

[0068] (Example 2) In the method for manufacturing the chip, the chip was manufactured in the same manner as in Example 1, except that the cutting blade rotation speed was set to 360 rpm.

[0069] (Example 3) In the method for manufacturing the chip, the chip was manufactured in the same manner as in Example 1, except that the cutting blade rotation speed was set to 900 rpm.

[0070] (Example 4) <Manufacturing of chloroprene polymer latex> Polymerization was carried out under the same conditions as in Example 1, except that the polymerization temperature was 35°C. Unreacted monomers were removed under reduced pressure to obtain chloroprene-based polymer latex 4 with a solid content of 40%.

[0071] <Manufacturing of chips containing chloroprene polymer rubber> The chip was manufactured in the same manner as in Example 1, except that chloroprene polymer latex 4 was used.

[0072] (Comparative Example 1) <Manufacturing of chips containing chloroprene polymer rubber> In the method for manufacturing the chip, the chip was manufactured in the same manner as in Example 1, except that the cutting blade rotation speed was set to 150 rpm.

[0073] (Comparative Example 2) <Manufacturing of chloroprene polymer latex> Polymerization was carried out under the same conditions as in Example 1, except that the amount of chloroprene monomer was 97.5 parts by mass, 2,3-dichloro-1,3-butadiene was 2.5 parts by mass, and the polymerization temperature was 40°C. Unreacted monomers were removed under reduced pressure to obtain chloroprene-based polymer latex 6 with a solid content of 40%.

[0074] <Manufacturing of chips containing chloroprene polymer rubber> The chip was manufactured in the same manner as in Example 1, except that chloroprene polymer latex 6 was used.

[0075] <Tip rating> The following evaluations were performed on the obtained chips.

[0076] <Heat storage> The heat retention capacity of the chip was evaluated using the following procedure. First, a K-type thermocouple was inserted into the chip so that its tip was near the center of the chip. The chip was then placed in an oven set to 150°C and heated until the temperature near the center reached 140°C. After the temperature near the center of the chip reached 140°C, the chip was removed to a 23°C environment, and the temperature near the center of the chip was measured over time. During this time, the chip was held in the air to prevent contact with other objects. Table 1 shows the temperatures immediately after removing the chip to the 23°C environment, and after 10 seconds, 30 seconds, and 60 seconds.

[0077] <Tip shape> The thickness, major axis, and minor axis of the chip were measured using calipers. The chip was scaly in shape, and the thickness direction was defined as the direction perpendicular to the approximately parallel planes. The longest length of the plane perpendicular to the thickness direction was defined as the major axis, and the length perpendicular to the major axis was defined as the minor axis. The measurement results are shown in Table 1.

[0078] <Crystallization time> The obtained chips were processed into a 3mm thick sheet using an 8-inch diameter roll (surface temperature 30°C). Three sheets of this sheet were placed in a mold measuring 6mm deep x 130mm long x 25mm wide, with the vertical direction aligning with the direction of the roll's threads (the direction along the roll's circumference when the sheet was processed), and pressed at 70°C for 20 minutes. During pressurization, five bumping cycles were performed to remove air. The sample removed from the mold was left to stand in a 23°C environment for 1 hour, and immediately after 1 hour, hardness measurement was performed using a Type A durometer according to JIS K 6253-3. The Type A durometer hardness at this time was defined as A0. Here, A0 represents the hardness before being placed in a -10°C environment. After measuring the hardness of the Type A durometer, the sample was placed in a -10°C low-temperature constant-temperature bath. The hardness of the sample was measured using a Type A durometer at regular intervals within the low-temperature constant-temperature bath. The Type A durometer hardness after X minutes from placement was defined as A X A X The time required for the temperature to exceed A0+20 was defined as the crystallization time. The measurement results are shown in Table 1. The hardness was measured using a durometer three times, with the measurement point shifted each time, and the average of the instantaneous values ​​was recorded. Here, the instantaneous value refers to the hardness at the moment the durometer needle is pressed against the sample.

[0079] <Liquid level inside the glass tube when toluene solution is stirred> 17g of chips were added to 153g of toluene and stirred until completely dissolved to prepare a 10% toluene solution of chloroprene polymer rubber. The 10% toluene solution of chloroprene polymer rubber, adjusted to 20°C, was placed in a beaker, a transparent glass tube with an inner diameter of 6mm and an outer diameter of 8mm was submerged 30mm into it, and the beaker was rotated at 2000rpm for 30 seconds. The difference between the lowest liquid level outside the glass tube (H0) and the highest liquid level inside the glass tube (H1) was measured using calipers. The results are shown in Table 1.

[0080] <Layer separation resistance of adhesives> 50 parts by mass of alkylphenol resin (Tamanol 526: manufactured by Arakawa Chemical Industries, Ltd.) and 3 parts by mass of magnesium oxide (Kyowa Mag #150: manufactured by Kyowa Chemical Industry Co., Ltd.) were dissolved in 100 parts by mass of cyclohexane and chelated at room temperature for 16 hours. Next, 100 parts by mass of chips, 1 part by mass of 2,6-di-t-butyl-4-methylphenol (Nocrac 200: manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), 3 parts by mass of magnesium oxide, 1 part by mass of zinc oxide, 180 parts by mass of cyclohexane, 75 parts by mass of n-hexane, 120 parts by mass of acetone, and 55 parts by mass of isopropyl acetate were added to the cyclohexane solution and mixed and stirred until the chips containing chloroprene polymer rubber were completely dissolved to obtain an adhesive composition.

[0081] The obtained adhesive composition was placed in a glass container and stored in a constant temperature bath at 60°C under light shielding. The appearance of the adhesive composition was observed for 8 weeks, and the week in which component separation was observed was recorded. The results are shown in Table 1.

[0082] <Yellowness> The chips were dissolved in toluene to a concentration of 5% by mass, and the absorbance at a wavelength of 440 nm was measured using a Shimadzu UV-2600 spectrophotometer to evaluate the hue (yellowness). The results are shown in Table 1.

[0083] <Solubility in organic solvents> 100g of chips were mixed with 400g of an organic solvent (cyclohexane / ethyl acetate = 1 / 1 (mass ratio)), and the mixture was stirred at 23°C. The time until the polymer was completely dissolved was measured. Completion of dissolution was determined visually. The results are shown in Table 1.

[0084] <Blocking resistance> The chips were processed into a 3mm thick sheet using an 8-inch diameter roll (surface temperature 30°C). This sheet was placed in a mold measuring 2mm deep x 150mm long x 100mm wide, with the length direction aligned with the grain direction of the sample, and pressed at 70°C for 20 minutes to produce a sheet. Two 60mm x 60mm test specimens were taken from the produced sheet. The two test specimens were stacked and sandwiched between glass plates measuring 2mm thick x 100mm wide x 100mm long, and kept in a 40°C constant temperature bath for 1 hour. After being removed and left at standard conditions (23°C) for 30 minutes, the two test specimens were separated, and the presence or absence of blocking (sticking) between the test specimens during separation was examined and evaluated according to the following evaluation criteria.

[0085] (Blocking of test specimens) ◎ There was no blocking between the test specimens. ○ The test specimens were slightly blocking each other. × The test specimens blocked each other significantly.

[0086] <Total content of alkaline earth metals, aluminum, and zinc> The content of alkaline earth metals, magnesium, aluminum, and zinc in the chip from Example 1 was measured by inductively coupled plasma atomic emission spectroscopy (ICP-OES). Specifically, the chip was first cut into pieces smaller than 5 mm square with scissors. 0.5 g of the cut sample was weighed out, 8 mL of nitric acid was added, and the mixture was decomposed and dissolved using a microwave decomposition apparatus. After cooling the resulting decomposition solution, it was diluted to a final volume of 25 mL and measured using an inductively coupled plasma atomic emission spectroscopy apparatus. It was confirmed that the chip from Example 1 contained 790 mg / kg of calcium.

[0087] [Table 1] [Explanation of symbols]

[0088] 1 glass rod 2. Maximum liquid level height H1 inside the glass tube 3. Minimum liquid level height on the outside of the glass tube H0

Claims

1. A method for manufacturing chips for an adhesive composition, The chip is heated to 140°C, and after being held in a 23°C room for 60 seconds, the temperature near the center of the chip is 130°C or lower. The aforementioned chip is press-molded at 70°C to form a 6mm thick sheet, removed from the mold, left to stand for 1 hour in a 23°C environment, and then the Type A durometer hardness measured according to JIS K 6253-3 is set to A0. The aforementioned 6 mm thick sheet is placed in a -10°C constant temperature bath, and when the Type A durometer hardness X minutes after placement is defined as AX, the time required for AX to exceed A0+20 is 1 to 150 minutes, and this is a chip. The aforementioned chip has a thickness of 10 mm or less. The aforementioned manufacturing method is Emulsion polymerization process to obtain a chloroprene polymer latex containing a chloroprene polymer by emulsion polymerization of a chloroprene monomer, A separation step to obtain a composition containing chloroprene polymer rubber by adding a coagulant to chloroprene polymer latex containing chloroprene polymer rubber, thereby separating the chloroprene polymer rubber from the chloroprene polymer latex. The process includes a molding step of molding the composition containing the chloroprene polymer rubber in an extruder to obtain the chip made of the chloroprene polymer rubber, The chloroprene-based polymer rubber comprises a chloroprene-based polymer, The chloroprene polymer consists of a homopolymer of chloroprene. In the emulsion polymerization step, the polymerization temperature is set to 35°C or lower. A manufacturing method comprising the molding process wherein the temperature of the chip immediately after extrusion is kept below 150°C.

2. A manufacturing method according to claim 1, A manufacturing method comprising the molding process wherein the temperature of the chip containing the chloroprene polymer rubber 60 seconds after dispensing is 130°C or lower.

3. A manufacturing method according to claim 1 or claim 2, In the molding process, the temperature of the die head is set to 120°C or lower. A manufacturing method wherein the ratio Y / Z of the ratio of the discharge speed Y (mm / min) of the chloroprene polymer rubber in the die head to the rotational speed Z (rpm) of the cutting blade that cuts the discharged chloroprene polymer rubber is set to 1 to 10.

4. A manufacturing method according to claim 1 or claim 2, A manufacturing method that does not include a step of water-cooling the chip after the molding step.

5. A manufacturing method according to claim 1 or claim 2, The process further includes a drying step to remove water from the composition containing the chloroprene-based polymer rubber separated in the separation step, The ambient temperature in the drying process is set to 130°C or lower. Manufacturing method.

6. A manufacturing method according to claim 5, wherein the separation step, the drying step, and the molding step are performed in an extruder.

7. The manufacturing method according to claim 1 or claim 2, wherein the absorbance at a wavelength of 440 nm of a toluene solution containing 5% by mass of the chloroprene polymer rubber, obtained by dissolving the chip in toluene, is 0.30 or less.

8. The manufacturing method according to claim 1 or claim 2, wherein the total content of alkaline earth metals, magnesium, aluminum, and zinc in the chip is 1 to 5000 mg / kg.

9. A method for producing an adhesive composition, A manufacturing method comprising the step of dissolving chips obtained by the manufacturing method described in claim 1 or claim 2 in an organic solvent.

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