JP2008111220A - Shoe press belt for papermaking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shoe press belt for papermaking, having excellent mechanical properties such as cracking resistance, flexural fatigue resistance and wear resistance. <P>SOLUTION: The shoe press belt is obtained by being embedded a reinforcing fiber substrate in polyurethane and comprises an outer layer and an inner layer, comprising the polyurethane, wherein the shoe press belt comprises a polyurethane layer obtained by curing a composition obtained by mixing a urethane prepolymer (a) having isocyanate at the terminal end and obtained by reacting p-phenylene-diisocyanate and polytetramethylene glycol, and a curing agent (b) selected from 1,4-butanediol, hydroquinonebis-β-hydroxyethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a papermaking shoe press belt (hereinafter sometimes referred to as a shoe press belt) used in a papermaking shoe press apparatus, and more particularly to a shoe press belt used in a closed type shoe press. More specifically, the shoe press belt has a resin layer made of polyurethane having a specific composition and hardness and is excellent in mechanical properties such as crack resistance, bending fatigue resistance, and wear resistance.

  In the papermaking shoe press, as shown in FIG. 5, a shoe press mechanism in which a loop-shaped shoe press belt 2 is interposed between the press roll 1 and the shoe 5 is used to form the press roll 1 and the shoe 5. In the press section to be dehydrated, the conveying felt 3 and the wet paper 4 are passed through.

  Further, as shown in FIG. 4, the shoe press belt 2 is configured by providing a polyurethane outer peripheral layer 21 and a polyurethane inner peripheral layer 22 on both surfaces of a reinforcing fiber base 6 encapsulated (embedded) in a polyurethane layer, and further pressing. A large number of concave grooves 24 are formed on the surface of the polyurethane outer peripheral layer 21 on the roll side, and the water squeezed from the wet paper 4 during the pressing is held in the concave grooves 24, and further, the retained water is transferred to the belt. It is transported out of the press section by its own rotation. Therefore, the convex portion 25 provided on the polyurethane outer peripheral layer 21 on the press roll side is resistant to cracking against vertical pressing force by the press roll 1, friction of the shoe press belt in the shoe press region, bending fatigue, It is required to improve mechanical properties such as bending fatigue resistance and wear resistance.

  For these reasons, polyurethane having excellent crack resistance is widely used as a resin material for forming the polyurethane outer peripheral layer 21 of the shoe press belt 2.

  For example, in a shoe press belt in which a reinforcing fiber base material and polyurethane are integrated, the polyurethane is formed of an outer peripheral layer and an inner peripheral layer, and the reinforcing fiber base material is embedded in the polyurethane, an outer peripheral layer is formed. The polyurethane to be used is a urethane prepolymer having an isocyanate group at the terminal obtained by reacting tolylene diisocyanate (TDI) and polytetramethylene glycol (PTMG) (Hyprene L: trade name, manufactured by Mitsui Chemicals), dimethylthio The curing agent containing toluene diamine has an equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent and the isocyanate group (NCO) of the urethane prepolymer of 1 <H / NCO <. Curing the composition in which the urethane prepolymer and the curing agent are mixed at a ratio of 1.15 The polyurethane having an JIS A hardness of 89 to 94 degrees and forming the inner peripheral layer is obtained by reacting 4,4′-methylenebis (phenylisocyanate (MDI) and polytetramethylene glycol (PTMG). The urethane prepolymer having an isocyanate group at the terminal obtained (manufactured by Mitsui Chemicals, Inc.), a mixed curing agent containing 65 parts of dimethylthiotoluenediamine and 35 parts of polytetramethylene glycol (PTMG), the activity of the curing agent The urethane prepolymer and the curing agent at a ratio in which the equivalent ratio (H / NCO) of the hydrogen group (H) to the isocyanate group (NCO) of the urethane prepolymer is 0.85 ≦ H / NCO <1. Shoe press bell formed from polyurethane obtained by curing a composition mixed with (See Patent Document 1 and Patent Document 2).

  Further, in the shoe press belt in which the reinforcing fiber base and the polyurethane are integrated, the polyurethane is formed of an outer peripheral layer and an inner peripheral layer, and the reinforcing fiber base is embedded in the polyurethane, the outer peripheral layer and the inner The polyurethane forming the circumferential layer is composed of urethane prepolymer having an isocyanate group at the terminal obtained by reacting tolylene diisocyanate (TDI) and polytetramethylene glycol (PTMG) (Hyprene L manufactured by Mitsui Chemicals), dimethyl A ratio in which the value of the equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer is 0.97 with a curing agent containing thiotoluenediamine The urethane prepolymer and the curing agent were mixed to form a composition. Shoe press belt IS A hardness is formed from 94 to 95 degrees of the polyurethane has been proposed (see Patent Document 3).

  Further, in the shoe press belt in which the reinforcing fiber base material and the polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane, the polyurethane contains a non-reactive polydimethylsiloxane liquid material, In addition, a urethane prepolymer having an isocyanate group at the terminal obtained by reacting tolylene diisocyanate (TDI) and polytetramethylene glycol (PTMG), dimethylthiotoluenediamine (ETHACURE300) or 4,4-methylenebis- (2 -Chloroaniline) A curing agent selected from {MOCA} is cured at a ratio of 0.9 ≦ H / NCO ≦ 1.10 and the urethane prepolymer and the curing agent are mixed. The formed shoe press belt having a JIS A hardness of 93 to 96 degrees, and the A polyurethane having a JIS A hardness of 90 to 93 degrees and containing a non-reactive polydimethylsiloxane liquid; a polyurethane having a JIS A hardness of 98 degrees and not containing a non-reactive polydimethylsiloxane liquid; JIS was formed by curing a composition in which the urethane prepolymer and the curing agent were mixed at a ratio of 0.9 ≦ H / NCO ≦ 1.10. A shoe press belt having an A hardness of 90 to 93 degrees has been proposed (see Patent Document 4).

JP 2002-146694 A JP 2005-120571 A JP 2005-307421 A JP 2006-144139 A

The shoe press belts described in the examples of Patent Documents 1 to 4 are formed so that both ends of a test piece are clamped by a clamp hand, and the clamp hand is formed so as to be reciprocally movable in the left-right direction. Using a device for examining the crack resistance in which the surface is directed to the rotating roll and the press shoe is moved in the direction of the rotating roll, and the test piece is pressurized, this device applies a tension of 3 kg / cm, pressure When the number of reciprocations until a crack was generated at a reciprocating speed of 40 cm / sec was measured while applying 36 kg / cm ² , it was excellent that cracks did not occur even after exceeding 1 million times.

  However, in recent years, the operating environment of shoe press belts has become increasingly severe as the operating speed has increased due to the improvement in paper productivity, the width of shoe press belts has increased to about 10 m, and the press section has increased pressure. Accordingly, there is a demand for further improvement of various characteristics as described above.

  An object of the present invention is to provide a shoe press belt having more excellent mechanical properties such as crack resistance, bending fatigue resistance, and wear resistance.

  The invention of claim 1 is a shoe press belt for papermaking in which a reinforcing fiber base material and polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane, wherein the polyurethane is p-phenylene diisocyanate, Urethane prepolymer (a) having an isocyanate group at the terminal obtained by reacting with polytetramethylene glycol, 1,4-butanediol, hydroquinonebis-βhydroxylethyl ether, 3,5-diethyltoluenediamine, and 3,5 -Providing a shoe press belt characterized by containing a polyurethane layer obtained by curing a composition mixed with a curing agent (b) selected from dimethylthiotoluenediamine, preferably The active hydrogen group (H) of the curing agent and the urethane prepolymer Curing the composition in which the urethane prepolymer and the curing agent are mixed at a ratio of equivalent ratio (H / NCO) to cyanate group (NCO) of 0.88 <H / NCO ≦ 1.0. It is preferable that it is formed from polyurethane having a JIS A hardness of 92 to 99 degrees.

  According to a second aspect of the present invention, there is provided a papermaking shoe press belt in which a reinforcing fiber base material and polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane, wherein an outer peripheral layer and an inner peripheral layer are made of the polyurethane. The polyurethane that is formed and forms the outer peripheral layer is a urethane prepolymer (a) having an isocyanate group at a terminal obtained by reacting p-phenylene diisocyanate with polytetramethylene glycol, 1,4-butanediol, A curing agent (b) selected from hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine, preferably an active hydrogen group (H) of the curing agent and an isocyanate of the urethane prepolymer The equivalent ratio (H / NCO) to group (NCO) is 0. Polyurethane formed from polyurethane having a JIS A hardness of 92 to 99 degrees obtained by curing a composition in which the urethane prepolymer and the curing agent are mixed at a ratio of 8 <H / NCO ≦ 1.0. In the polyurethane forming the inner peripheral layer, an isocyanate compound selected from 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and 4,4′-methylene bis (phenyl isocyanate) and polytetramethylene glycol are used. A urethane prepolymer having an isocyanate group at the terminal obtained by the reaction, a curing agent selected from dimethylthiotoluenediamine, hydroquinone bis-βhydroxylethyl ether, 3,5-diethyltoluenediamine, and 1,4-butanediol; Preferably the active hydrogen of the curing agent The urethane prepolymer and the curing agent in such a ratio that the equivalent ratio (H / NCO) of (H) to the isocyanate group (NCO) of the urethane prepolymer is 0.93 <H / NCO <1.05. A shoe press belt which is formed from a polyurethane inner peripheral layer obtained by curing a composition in which the above is mixed, and a reinforcing fiber base is embedded in the polyurethane inner peripheral layer.

  In the invention of claim 3, the reinforcing fiber base and the polyurethane layer are integrated, and the reinforcing fiber base is embedded in the polyurethane intermediate layer, and the outer peripheral polyurethane layer and the inner layer are formed on both sides of the intermediate layer. In the shoe press belt for papermaking in which the peripheral polyurethane layer is laminated, the polyurethane forming the outer peripheral polyurethane layer and the inner peripheral polyurethane layer is formed at the end obtained by reacting p-phenylene-diisocyanate with polytetramethylene glycol. Urethane prepolymer (a) having an isocyanate group and a curing agent selected from 1,4-butanediol, hydroquinone bis-βhydroxylethyl ether, 3,5-diethyltoluenediamine and 3,5-dimethylthiotoluenediamine ( b), preferably an active hydrogen group ( ) And the isocyanate group (NCO) of the urethane prepolymer at a ratio of 0.88 <H / NCO ≦ 1.0, the urethane prepolymer and the curing agent have a ratio of 0.88 <H / NCO ≦ 1.0. A polyurethane formed from a polyurethane having a JIS A hardness of 92 to 99 degrees obtained by curing the mixed composition, and the polyurethane forming the intermediate layer is 2,4-tolylene diisocyanate, 2,6- A urethane prepolymer having an isocyanate group at the terminal obtained by reacting an isocyanate compound selected from tolylene diisocyanate and 4,4′-methylenebis (phenylisocyanate) with polytetramethylene glycol, dimethylthiotoluenediamine, hydroquinonebis -Β hydroxyl ethyl ether, 3,5-die A curing agent selected from rutoluenediamine and 1,4-butanediol, preferably an equivalent ratio (H / NCO) of active hydrogen groups (H) of the curing agent to isocyanate groups (NCO) of the urethane prepolymer A shoe press belt formed of polyurethane obtained by curing a composition in which the urethane prepolymer and the curing agent are mixed at a ratio of 0.93 <H / NCO <1.05 It is to provide.

  Uses p-phenylene diisocyanate and polytetramethylene glycol, which are easy to form a linear polymer, as the urethane prepolymer material for the polyurethane outer layer of the shoe press belt facing the wet paper side, and forms a linear polymer as a curing agent. Since an excellent polyurethane is formed by using a compound selected from aliphatic 1,4-butanediol, hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine, and dimethylthiotoluenediamine, A shoe press belt having mechanical properties such as crack resistance, bending fatigue resistance, and wear resistance is provided. The durability of the shoe press belt can be expected to be improved by 1.5 times or more than the durability (usually about 2 to 3 months) of currently used shoe press belts.

  Further, in the shoe press belt according to claim 3, the polyurethane forming the outer peripheral layer and the inner peripheral layer is made of polyurethane having a JIS A hardness of 92 to 99 degrees so as to improve the wear resistance, and the intermediate layer has a stretchability. It is expected that the durability of the shoe press belt will be further improved by reinforcing the flex resistance with excellent polyurethane.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a cross-sectional view of a shoe press belt of the present invention, in which a reinforcing fiber base material and polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane. FIG. 1A shows a single polyurethane, FIG. 1B shows a two-layer polyurethane, and FIG. 1C shows a three-layer polyurethane. In any shoe press belt, the polyurethane outer peripheral layer of the shoe press belt facing the wet paper web is formed of the polyurethane according to claim 1. FIG. 2 is a stress-strain curve (stress-strain curve) of various polyurethanes, and FIG. 3 is a correlation diagram of strain and tear stress in various polyurethane cut-in angle shapes. FIG. 4 is an example of a cross-sectional view of a shoe press belt in which concave grooves 24 are formed in the present invention. There are various types depending on the shape and depth of the groove and the ratio of the width of the groove and protrusion. FIG. 5 is a simplified diagram of a shoe press mechanism in a paper machine. FIG. 6 is an explanatory diagram of a bending test similar to the demature bending test defined in JIS used in the present invention. Using this tester, a crack progress test was conducted under the following conditions in an atmosphere of 20 ° C. and a relative humidity of 52%. The size of the test piece 61 is a width of 25 mm, a length of 185 mm (including 20 mm on the side of the gripping margin), a length of 150 mm between the gripping tools 62, a thickness of 3.4 mm, and a semicircular recess 61 a having a radius of 1.5 mm at the center. It was. The reciprocating motion was set such that the maximum distance between grippers was 100 mm, the minimum distance was 35 mm, the moving distance was 65 mm, and the reciprocating speed was 360 reciprocating / minute. The cut was about 2.1 mm long in the width direction at the center of the test piece. The left and right grips were set to make an angle of 45 ° with respect to the reciprocating direction. The bending was repeated under these conditions, and the length of the crack was measured every predetermined number of times. The test was completed when the crack length exceeded the initial cut length of 2.1 mm to 15 mm.

  As the reinforcing fiber base 6, not only the woven fabrics described in Patent Documents 1 to 4 but also reinforcing fiber bases described in other documents can be used. For example, it is a lattice-like material in which a 5000 dtex multifilament yarn of polyethylene terephthalate (PET) fiber is used as warp and weft, the warp is sandwiched between wefts, and the intersection of the weft and the warp is joined by polyurethane adhesion. As the fiber material, polyamide fiber such as aramid fiber, nylon 6,6, nylon 6,10, nylon 6, etc. may be used instead of polyethylene terephthalate. Further, different fibers may be used for the warp and the weft, and the thickness of the warp and the weft may be different from 5000 dtex and 7000 dtex.

  The polyurethane forming the outer peripheral layer 21 of the shoe press belt is composed of urethane prepolymer (a) having an isocyanate group at the terminal obtained by reacting p-phenylene diisocyanate with polytetramethylene glycol, 1,4-butane. A curing agent (b) selected from diol, hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine, and dimethylthiotoluenediamine, an active hydrogen group (H) of the curing agent and the urethane prepolymer Curing the composition in which the urethane prepolymer and the curing agent are mixed at a ratio of equivalent ratio (H / NCO) to isocyanate group (NCO) of 0.88 <H / NCO ≦ 1.0. A polyurethane having a JIS A hardness of 92 to 99 degrees, preferably 95 to 99 degrees. is there.

  Urethane prepolymer (a) As an isocyanate compound as a raw material, p-phenylene diisocyanate (PPDI) can be used in an amount of 55 to 100 mol%, preferably 75 mol% or more in the isocyanate compound. 4-tolylene-diisocyanate (2,4-TDI), 2,6-tolylene-diisocyanate (2,6-TDI), 4,4′-methylenebis (phenylisocyanate) (MDI), 1,5-naphthylene-diisocyanate ( NDI) is 45 mol% or less, preferably 25 mol% or less.

  Polytetramethylene glycol (PTMG) can be used in the polyol as a polyol as a raw material for the urethane prepolymer (a) in an amount of 65 to 100 mol%, preferably 85 mol% or more. Polyol other than PTMG includes polyoxypropylene glycol (PPG). ), Polyethylene adipate (PEA), polycaprolactone diol (PCL), trimethylolpropane (TMP), polycarbonate diol (PCD) (herein polycarbonate diol refers to C6-homo-polycarbonate diol, C6 / C5 carbonate diol copolymer and C6 / C4 carbonate diol copolymer) is 35 mol% or less, preferably 15 mol% or less.

  As the curing agent, a curing agent selected from 1,4-butanediol, hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine, and dimethylthiotoluenediamine can be used at a ratio of 15 mol% or less. , 4,4′-methylenedianiline (MDA), 4,4′-methylene-bis- (2-chloroaniline) (MOCA) and other curing agents may be used in combination.

  As shown in FIG. 1A, the polyurethane of the shoe press belt may be used alone, or may be used by laminating with polyurethane having other composition.

  For example, as in the shoe press belt shown in FIG. 1B, a reinforcing fiber base material and polyurethane are integrated, the reinforcing fiber base material is embedded in the polyurethane, and an outer peripheral layer and an inner peripheral layer are formed. In the shoe press belt formed of the polyurethane, the polyurethane forming the outer peripheral layer is a urethane prepolymer (a) having an isocyanate group at the terminal obtained by reacting p-phenylene diisocyanate with polytetramethylene glycol. A curing agent (b) selected from 1,4-butanediol, hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine, and dimethylthiotoluenediamine, and an active hydrogen group (H) of the curing agent Equivalent ratio of urethane prepolymer to isocyanate group (NCO) (H / The JIS A hardness obtained by curing the composition in which the urethane prepolymer and the curing agent are mixed at a ratio such that the value of (CO) is 0.88 <H / NCO ≦ 1.0 is 92 to 99 degrees. Polyurethanes formed from polyurethane and forming the inner peripheral layer are 2,4-tolylene-diisocyanate (2,4-TDI), 2,6-tolylene-diisocyanate (2,6-TDI) and 4, A urethane prepolymer having an isocyanate group at the terminal obtained by reacting an isocyanate compound selected from 4′-methylenebis (phenylisocyanate) and polytetramethylene glycol, dimethylthiotoluenediamine, hydroquinonebis-βhydroxylethyl ether, 3,5-diethyltoluenediamine and 1,4-buta A curing agent selected from diols has an equivalent ratio (H / NCO) of active hydrogen groups (H) of the curing agent and isocyanate groups (NCO) of the urethane prepolymer of 0.93 <H / NCO. It is formed from a polyurethane inner peripheral layer obtained by curing a composition in which the urethane prepolymer and the curing agent are mixed at a ratio of <1.05, and a reinforcing fiber base is embedded in the polyurethane inner peripheral layer. There is a shoe press belt.

  Further, as in the shoe press belt shown in FIG. 1 (c), the reinforcing fiber base and the polyurethane layer are integrated, and the polyurethane layer has the reinforcing fiber base embedded in the polyurethane intermediate layer. In the shoe press belt in which the outer peripheral polyurethane layer and the inner peripheral polyurethane layer are laminated on both sides of the layer, the polyurethane forming the outer peripheral polyurethane layer and the inner peripheral polyurethane layer reacts with p-phenylene-diisocyanate and polytetramethylene glycol. Selected from the urethane prepolymer (a) having an isocyanate group at the terminal obtained, and 1,4-butanediol, hydroquinonebis-βhydroxylethyl ether, 3,5-diethyltoluenediamine, and dimethylthiotoluenediamine. The curing agent (b) The value of the equivalent ratio (H / NCO) of the hydrogen group (H) to the isocyanate group (NCO) of the urethane prepolymer is 0.88 <H / NCO ≦ 1.0. A polyurethane formed from a polyurethane having a JIS A hardness of 92 to 99 degrees obtained by curing a composition mixed with a curing agent, and the polyurethane forming the intermediate layer is 2,4-tolylene-diisocyanate ( 2,4-TDI), 2,6-tolylene-diisocyanate (2,6-TDI) and 4,4′-methylenebis (phenyl isocyanate) are obtained by reacting polytetramethylene glycol with an isocyanate compound. Urethane prepolymer having an isocyanate group at the end, 3,5-dimethylthiotoluenediamine, -A curing agent selected from butanediol, 3,5-diethyltoluenediamine and hydroquinone bis-β hydroxyl ethyl ether, and an active hydrogen group (H) of the curing agent and an isocyanate group (NCO) of the urethane prepolymer. Formed from a polyurethane obtained by curing a composition in which the urethane prepolymer and the curing agent are mixed at an equivalent ratio (H / NCO) value of 0.93 <H / NCO <1.05. It is a shoe press belt.

  Even in shoe press belts using these laminated polyurethanes, as long as the object of the present invention is not impaired, the content of other polyols, isocyanate compounds, and curing agent compounds is 35 mol% or less, preferably 15 mol% or less. A polyol, an isocyanate compound, and a curing agent can be used in combination.

  In order to produce a shoe press belt, for example, a mandrel coated with a release agent on the surface is mixed with a urethane prepolymer and a curing agent mixture that forms an inner polyurethane layer while rotating the mandrel on the mandrel surface. It is applied and impregnated so that an inner polyurethane layer is formed to a thickness of ˜3.5 mm, and the resin layer is heated to 70 to 140 ° C. and precured for 0.5 to 1 hour. A reinforcing fiber substrate is wound from above, and then a mixture of urethane prepolymer and a curing agent for forming an intermediate layer is applied in an amount of 0.5 to 2 mm, impregnated into a base fabric and adhered to an inner peripheral layer, and the resin The layer is precured at 50-120 ° C. for 0.5-1 hour to form an intermediate layer reinforced with a reinforcing fiber substrate. After that, while rotating the mandrel, a mixture of urethane prepolymer and a curing agent that forms an outer polyurethane layer is applied and impregnated so that an outer peripheral polyurethane layer having a thickness of 1.5 to 4 mm is formed on the surface of the intermediate layer. The resin is heated and cured at 70 to 140 ° C. for 2 to 20 hours. Thereafter, the grooves shown in FIG. 4 are engraved on the outer peripheral layer. The engraving of the groove on the outer polyurethane layer may be engraved by pressing a heated embossing roll having a groove depth height projection on the surface during the heat curing of the outer polyurethane layer, on the outer polyurethane layer being cured. The mandrel includes a heating device.

  As another method for producing a shoe press belt, for example, a polyurethane layer having a thickness of 0.8 to 3 mm is formed by mixing a urethane prepolymer and a curing agent that form an inner polyurethane layer on a mandrel having a release agent applied on the surface. The urethane prepolymer is formed so that an intermediate layer is formed after the reinforcing fiber base material is wound around the outer surface of the cured polyurethane layer. And 0.5 to 2 mm of the mixture of the curing agent and impregnating the base fabric and adhering to the inner peripheral layer, the resin layer is precured at 50 to 120 ° C. for 0.5 to 1 hour, and the fiber An intermediate layer reinforced with a substrate is formed. Next, a mixture of a urethane prepolymer and a curing agent that form the outer peripheral surface is applied so as to form a polyurethane layer having a thickness of 2 to 4 mm, and post-cured at 70 to 140 ° C. for 12 to 20 hours. Next, there is a method in which a groove is cut with a cutting bit on the outer peripheral surface of the laminated polyurethane in which the reinforcing fiber base is embedded, and then the outer peripheral surface is polished with sandpaper or a polyurethane polishing cloth.

  A method for producing a shoe press belt having an intermediate layer is, for example, by mixing a mixture of a urethane prepolymer and a curing agent that form an inner peripheral layer on a mandrel coated with a release agent on the surface, with a thickness of 0.8 to 3 mm. It was applied so that a layer was formed, pre-cured at 50 to 140 ° C. for 0.5 to 2 hours, and then a reinforcing fiber base material previously prepared on the outer surface of the inner peripheral layer was embedded 1 to A polyurethane intermediate layer with a thickness of 2 to 4 mm is formed by wrapping a polyurethane intermediate layer with a thickness of 2 mm and pressing the intermediate layer with a nip roll heated to 50 to 140 ° C. and further forming a mixture of a urethane prepolymer and a curing agent to form the outer peripheral surface. And post-cured at 70-140 ° C. for 2-20 hours. Next, there is a method in which the outer peripheral surface of the laminated polyurethane in which the reinforcing fiber base material is embedded is polished with sandpaper or a polyurethane polishing cloth, and then the outer peripheral surface is cut with a cutting tool. In addition, there is a method of producing with two rolls.

  As another method for manufacturing a shoe press belt, there is a method using two rolls instead of a mandrel. An endless reinforcing fiber base is stretched between two rolls. First, a composition containing a urethane prepolymer and a curing agent is applied from the surface of the reinforcing fiber base, and the reinforcing fiber base is impregnated. After the pre-curing at 50 to 120 ° C. for 0.5 to 2 hours, a polyurethane layer having a thickness of 0.5 to 3 mm is formed from a mixture of a urethane prepolymer and a curing agent that forms the inner peripheral polyurethane layer of the shoe press belt. An integrated structure in which the inner surface layer of the shoe press belt and the fiber reinforced substrate are bonded to each other by curing the surface at 70 to 140 ° C. for 2 to 12 hours, polishing the surface with sandpaper or a polishing cloth. create. Next, this monolithic structure is inverted and stretched on two rolls. Next, a composition containing a urethane prepolymer and a curing agent is applied from the surface of the stretched monolithic structure, impregnated into a reinforcing fiber base material, and a mixture of the urethane prepolymer and the curing agent is further applied to the surface. It is applied to a thickness of 5 to 4 mm and cured at 70 to 140 ° C. for 2 to 20 hours. After the curing is completed, the surface layer is polished to a predetermined thickness, and a groove is cut with a cutting tool to form an outer peripheral layer.

  Below, in order to evaluate the physical property of the polyurethane which forms the belt for shoe presses, a polyurethane test piece is manufactured.

Reference example 1
Urethane prepolymer obtained by reacting p-phenylene-diisocyanate (PPDI) and polytetramethylene glycol (PTMG) (NCO% is 5.51%, viscosity at 55 ° C. is 1,800 cps, preheating temperature is 66 ° C.) and A composition comprising 1,4-butanediol (H / NCO ratio is 0.95) is poured into a preheated mold, heated to 127 ° C., precured at 127 ° C. for 0.5 hours, and then gold The mold was removed from the mold and post-cured at 127 ° C. for 16 hours to obtain a cured polyurethane sheet having a JIS A hardness of 98.1 degrees. A test piece (thickness 1.5 mm) was prepared from this sheet.

Reference example 2
Urethane prepolymer obtained by reacting p-phenylene-diisocyanate (PPDI) with polytetramethylene glycol (PTMG) (NCO% is 5.51%, viscosity at 55 ° C is 1,800 cps, preheating temperature is 120 ° C) and A composition comprising hydroquinone bis-β hydroxyl ethyl ether (H / NCO ratio is 0.95) is poured into a preheated mold, heated to 127 ° C., and precured at 127 ° C. for 0.5 hours. After curing at 127 ° C. for 16 hours, a cured polyurethane sheet having a JIS A hardness of 98.1 degrees was obtained. A test piece was prepared from this sheet.

Reference example 3
Urethane prepolymer (NCO% is 5.51%, preheating temperature 66 ° C.) obtained by reacting p-phenylene-diisocyanate (PPDI) with polytetramethylene glycol (PTMG) and dimethylthiotoluenediamine (ETHACURE300) The composition (H / NCO ratio is 0.95) is poured into a preheated mold, heated to 100 ° C., precured at 100 ° C. for 0.5 hours, and then at 100 ° C. for 16 hours. Cured to obtain a cured polyurethane sheet having a JIS A hardness of 96.2 degrees. A test piece was prepared from this sheet.

Reference Examples 4-6
A polyurethane sheet specimen was produced from the urethane prepolymer and the curing agent shown in Table 1 in the same manner as in Reference Examples 1 to 3 under the molding conditions shown in the same table. In addition, the compounding quantity of the hardening | curing agent in a table | surface is the weight part number of the hardening | curing agent with respect to 100 weight part of urethane prepolymers.

  About the obtained test piece, JIS A hardness, tensile strength (JIS K6251: dumbbell No. 3, tensile speed 500 mm / min), tear strength (JIS K6252, tear speed 500 mm / min, with angle notch), compressive strain ( The physical properties of JIS K6262), abrasion test, and demacha-type bending test were evaluated. The obtained physical properties are shown in Table 1. Further, FIG. 2 shows a stress-strain curve of polyurethane (Reference Examples 1, 2, 3, and 5), and FIG. 3 shows a correlation diagram between stress and strain of tear strength.

  For the wear test, use the apparatus shown in FIG. 4 of Japanese Patent Application Laid-Open No. 2006-144139, attach a test piece to the lower part of the press board, and press a rotating roll with a friction element on the outer surface (surface to be measured). While rotating. At this time, the pressure by the rotating roll was 9.6 kg / cm, and the rotating speed of the rotating roll was 100 m / min. After the rotation, the thickness reduction amount (wear amount) of the belt sample was measured.

  For the bending test, using a tester similar to the Demach type bending test defined in JIS-K-6260 (2005) shown in FIG. A crack progress test was conducted. The size of the test piece 61 is a width of 25 mm, a length of 185 mm (including 20 mm on the side of the gripping margin), a length of 150 mm between the gripping tools 62, a thickness of 3.4 mm, and a semicircular recess 61 a having a radius of 1.5 mm at the center. It was. The reciprocating motion was set such that the maximum distance between grippers was 100 mm, the minimum distance was 35 mm, the moving distance was 65 mm, and the reciprocating speed was 360 reciprocating / minute. The cut was about 2 mm long in the width direction at the center of the test piece. The left and right grips were set to make an angle of 45 ° with respect to the reciprocating direction. Bending was repeated under these conditions, and the length of the crack was measured every predetermined number of strokes. The number of strokes referred to here is a value obtained by multiplying the test time by the reciprocating speed. Table 2 shows the crack length for each number of strokes in each example. The test was terminated when the crack length exceeded 15 mm from the initial cut length measurement value (about 2 mm), and an approximate curve of the number of strokes and the crack length was drawn, and the crack length was 15 mm. The number of strokes was read, and the value obtained by dividing the grown crack length (crack length 15 mm—initial cut length measurement value) by the number of strokes at that time was taken as the dematched bending test result.

  From Tables 1 and 2, although the flex resistance of the urethane resin used in the shoe press belt of Example 1 is about 98 degrees compared to about 95 degrees of the hardness of the commercial product, the conventional shoe The performance of the press belt or the resin for shoe press belt described in the patent document (Comparative Example 1) is about 10 times or more that of the conventional shoe press belt or the resin for shoe press belt described in the Patent Document (Comparative Example 2). It is understood that it has more than twice the performance. Similarly, it is understood that the resin according to the present invention is improved by 30% or more in terms of abrasion resistance as compared with the conventional shoe press belt or the resin described in the patent literature.

  Next, the example which manufactures a shoe press belt using the polyurethane composition used for the reference example 1, the reference example 2, the reference example 3, the reference example 4, and the reference example 6 is described.

Example 1
Step 1: A release agent (KS-61: manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of a mandrel having a diameter of 1500 mm that can be appropriately rotated by a driving means. Next, while rotating the mandrel, the urethane prepolymer (PPDI / PTMG-based prepolymer) used in Reference Example 1 and a curing agent made of 1,4-butanediol (manufactured by Mitsubishi Chemical Corporation) are combined with H / NCO. The composition mixed so that the equivalence ratio is 0.95 is applied on a rotating mandrel to a spiral with a thickness of 1.4 mm by an injection molding nozzle that can move parallel to the rotation axis of the mandrel. The urethane resin layer was formed (hereinafter referred to as spiral coating). The mandrel was rotated for 10 minutes at room temperature, and the resin was heated at 127 ° C. for 0.5 hours with a heating device attached to the mandrel and precured to produce a shoe side layer (inner circumferential layer). .

  Step 2: Polyethylene terephthalate fiber 5,000 dtex multifilament yarn twisted weft, polyethylene terephthalate fiber 550 dtex multifilament yarn warp, warp yarn sandwiched between weft yarns, and the intersection of weft and warp yarns by urethane resin adhesion A joined lattice-shaped material (a warp density of 1 / cm and a weft density of 4 / cm) was prepared. A plurality of lattice-like materials were arranged in a single layer on the outer periphery of the shoe side layer with wefts along the mandrel axial direction. Then, a 6,700 dtex multifilament yarn of polyethylene terephthalate fiber was spirally wound at a pitch of 30/5 cm on the outer periphery of the lattice material to form a bobbin layer. Thereafter, the polyurethane composition was applied in an amount of about 1.6 mm so as to close the gap between the lattice-like material and the pincushion layer and integrated to form an intermediate layer reinforced with a fiber base material.

  Step 3: From the top of the pincushion layer, the same polyurethane composition as the resin used for the shoe side layer is impregnated with a spiral coat to a thickness of about 2.5 mm, heated at 127 ° C. for 16 hours and post-cured. A wet paper web side layer (outer peripheral layer) was prepared. The surface of the wet paper web layer is polished so that the total thickness is 5.2 mm, and then a ditch (groove width 0.8 mm, depth 0.8 mm, pitch width 2) in the MD direction of the belt with a rotary blade. .54 mm) were formed to obtain a shoe press belt.

Example 2
A shoe press belt was obtained in the same manner as in Example 1 except that instead of the polyurethane composition of Reference Example 1, the polyurethane composition (a composition of PPDI / PTMG-based prepolymer and HQEE) used in Reference Example 2 was used. .

Example 3
A shoe press belt was obtained in the same manner as in Example 1, except that the polyurethane composition (composition of PPDI / PTMG prepolymer and ETHACURE300) used in Reference Example 3 was used instead of the polyurethane composition of Reference Example 1. .

Comparative Example 1
In Example 1, instead of the polyurethane composition of Reference Example 1, the polyurethane composition (composition of TDI / PTMG prepolymer and ETHACURE300) used in Reference Example 4 was used. A shoe press belt was obtained in the same manner except that the post-curing was 100 hours at 100 ° C. for 5 hours.

Comparative Example 2
A shoe press belt was obtained in the same manner as in Comparative Example 1, except that the polyurethane composition (composition of MDI / PTMG prepolymer and ETHACURE300) used in Reference Example 6 was used instead of the polyurethane composition of Reference Example 4. .

  The obtained shoe press belt was subjected to a wear test and a bending fatigue test. The abrasion test of the belt sample was evaluated with the product belt sample after grooving. Since the product belt sample after grooving has a tendency to wear more than the flat resin test sample, the test conditions were set as follows. For the wear test, use the apparatus shown in FIG. 4 of Japanese Patent Application Laid-Open No. 2006-144139, attach a belt sample to the lower part of the press board, and press a rotating roll with a friction element on the outer surface (surface to be measured). While rotating. At this time, the pressure by the rotating roll was 6.6 kg / cm, the rotating speed of the rotating roll was 100 m / min, and the rotating roll was rotated for 45 seconds. After the rotation, the thickness reduction amount (wear amount) of the belt sample was measured. The abrasion test of the belt sample was evaluated with the sample before grooving. The amount of wear (average of 5 points) is 0.213 mm in Example 1, 0.471 mm in Example 2, 0.501 in Example 3, 0.269 mm in Comparative Example 1, 0.615 mm in Comparative Example 2, Met.

In the bending fatigue test, a crack generation test was performed under the following conditions in an atmosphere of 20 ° C. and a relative humidity of 52% using the apparatus shown in FIG. The size of the test piece 71 was 60 cm wide and the length between grips was 70 mm. By giving an arc-shaped reciprocating motion to the lower gripping tool 72a, the upper gripping tool 72b and the test piece also reciprocated in an arc shape so that the test piece is bent and fatigued at the tip of the lower gripping tool. The distance from the center of the arc to the tip of the lower gripping tool was 168 mm, the moving distance of the lower gripping tool was 161 mm, and the reciprocation speed was 162 reciprocations / minute. The weight of the upper gripping tool was 400 g. The bending was repeated under these conditions, and the number of bendings until a crack occurred was measured.
The number of bendings was 700,000 for Examples 1 to 3 without cracking, 200,000 for Comparative Example 1, and 500,000 for Comparative Example 2.

  From Table 3, the shoe press belts of Example 1, Example 2 and Example 3 are excellent in wear resistance, and the bending resistance is the shoe press belt of the prior art or the shoe press belt described in the patent literature (Comparative Example 1). It is understood that the performance of the shoe press belt is about 1.3 times that of a commercially available product or a shoe press belt described in the patent literature (Comparative Example 2). It is understood that there is a marked improvement.

Example 4
Step 1: A release agent (KS-61: manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of a mandrel having a diameter of 1500 mm that can be appropriately rotated by a driving means. Next, a curing agent (manufactured by Mitsubishi Chemical Corporation) comprising the urethane prepolymer (PPDI / PTMG / 1,4-butanediol) used in Reference Example 1 and 1,4-butanediol on the mandrel surface while rotating the mandrel. ) And a composition in which the H / NCO equivalent ratio is 0.95 is applied to a thickness of 0.8 mm using a doctor bar, and left at room temperature for 10 minutes while rotating the mandrel. The resin was pre-cured by heating at 127 ° C. for 0.5 hours with a heating device attached to the mandrel.

  Step 2: The polyurethane composition (PPDI / PTMG / HQEE) used in Reference Example 2 was applied to the surface of the precured inner peripheral layer polyurethane to a thickness of 1.4 mm using a doctor bar, and the mandrel was rotated. The resin was allowed to stand at room temperature for 10 minutes, and the resin was further pre-cured by heating at 127 ° C. for 0.5 hour using a heating device attached to the mandrel.

  Step 3: Polyethylene terephthalate fiber 5000 dtex multifilament yarn twisted weft, polyethylene terephthalate fiber 550 dtex multifilament yarn warp, warp is sandwiched between wefts, and the intersection of weft and warp is bonded by urethane resin bonding A lattice-shaped material (a warp density was 1 / cm and a weft density was 4 / cm) was prepared. A plurality of lattice-like materials were arranged in a single layer on the outer periphery of the shoe side layer with wefts along the mandrel axial direction. Then, a 6,700 dtex multifilament yarn of polyethylene terephthalate fiber was spirally wound at a pitch of 30/5 cm on the outer periphery of the lattice material to form a bobbin layer. Then, about 1.6 mm of the polyurethane composition of Reference Example 4 was applied and integrated so as to close the gap between the lattice material and the pincushion layer to form an intermediate layer reinforced with a fiber base material.

  Step 4: A polyurethane composition of Reference Example 4 (TDI / PTMG / ETHACURE300) used for the shoe side layer is impregnated and coated to a thickness of 1.4 mm from above the bobbin layer and heated at 100 ° C. for 0.5 hour. Cured to form an intermediate polyurethane layer.

  Step 5: The polyurethane composition of Reference Example 2 (PPDI / PTMG / HQEE) is applied to the outer peripheral surface of the intermediate layer to a thickness of about 2.0 mm and cured by heating at 127 ° C. for 15 hours to form an outer peripheral polyurethane layer. did.

  The outer peripheral polyurethane layer surface of the wet paper web side layer is polished so that the total thickness becomes 5.5 mm, and then a ditch groove (groove width 0.8 mm, depth 0.8 mm, A large number of pitch widths (2.54 mm) were formed to obtain shoe press belts.

Example 5
Step 1: A release agent (KS-61: manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of a mandrel having a diameter of 1500 mm that can be appropriately rotated by a driving means. Next, while rotating the mandrel, the polyurethane composition of Reference Example 4 (TDI / PTMG / ETHACURE300) was applied to the mandrel surface with a spiral coat to a thickness of 1.4 mm, and the mandrel was rotated for 10 minutes at room temperature. The resin was then pre-cured by heating at 100 ° C. for 0.5 hours using a heating device attached to the mandrel.

  Step 2: A piece of woven fabric (weft mesh 30/5 cm, warp mesh 40 / 5 cm) was prepared. A plurality of woven fabric pieces were arranged in a single layer on the outer periphery of the shoe side layer with wefts along the mandrel axial direction. Then, a 7000 dtex multifilament yarn of polyethylene terephthalate fiber was spirally wound at a pitch of 30/5 cm on the outer periphery of the fabric piece to form a wound layer. Then, the polyurethane composition (composition of TDI / PTMG prepolymer and ETHACURE300) used in Reference Example 4 was applied to a thickness of 1.6 mm using a doctor bar so as to close the gap between the fabric piece and the pincushion layer. To form an intermediate layer reinforced with a fiber substrate.

  Step 3: After applying the polyurethane composition of Reference Example 1 (PPDI / PTMG / 1,4-butanediol) to a thickness of about 2.5 mm by spiral coating from above the bobbin layer and heating at 127 ° C. for 16 hours. Cured. The surface of the wet paper web layer is polished so that the total thickness is 5.2 mm, and then a ditch (groove width 0.8 mm, depth 0.8 mm, pitch width 2) in the MD direction of the belt with a rotary blade. .54 mm) were formed to obtain a shoe press belt.

Example 6
Step 1: A release agent (KS-61: manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to a polished surface of a mandrel having a diameter of 1500 mm that can be appropriately rotated by a driving means. Next, while rotating the mandrel, the polyurethane composition (MDI / PTMG / ETHACURE300) used in Reference Example 6 was applied to the mandrel surface to a thickness of 0.9 mm by spiral coating, and the mandrel was rotated at room temperature. The resin was left to stand for 10 minutes, and further, the resin was pre-cured by heating at 100 ° C. for 0.5 hours using a heating device attached to the mandrel.

  Step 2: Polyethylene terephthalate fiber 5000 dtex multifilament yarn twisted weft, polyethylene terephthalate fiber 550 dtex multifilament yarn warp, warp yarn is sandwiched between weft yarns, and the intersection of weft and warp yarns joined by urethane resin bonding A lattice-shaped material (a warp density was 1 / cm and a weft density was 4 / cm) was prepared. A plurality of lattice-like materials were arranged in a single layer on the outer periphery of the shoe side layer with wefts along the mandrel axial direction. Then, a 6,700 dtex multifilament yarn of polyethylene terephthalate fiber was spirally wound at a pitch of 30/5 cm on the outer periphery of the lattice material to form a bobbin layer. After that, the polyurethane composition (MDI / PTMG / ETHACURE300) was applied by using a doctor bar to an extent of about 1.6 mm so as to close the gap between the lattice material and the pincushion layer, and was reinforced with a fiber base material. A layer was formed.

  Step 3: The polyurethane composition of Reference Example 1 (PPDI / PTMG / 1,4-butanediol) is applied to the thickness of about 3 mm by spiral coating from above the pincushion layer, and is post-cured by heating at 127 ° C. for 16 hours. It was. The surface of the wet paper web layer is polished so that the total thickness is 5.2 mm, and then a ditch (groove width 0.8 mm, depth 0.8 mm, pitch width 2) in the MD direction of the belt with a rotary blade. .54 mm) were formed to obtain a shoe press belt.

  The shoe press belt of the present invention is superior in crack resistance, bending fatigue resistance, and wear resistance compared to existing products, and is expected to withstand 1.5 times or more use of conventional shoe press belts. The

It is sectional drawing of a shoe press belt. It is a stress-strain curve (stress-strain curve) of various polyurethanes. It is a correlation diagram of distortion and tear stress of various polyurethanes. It is sectional drawing of a shoe press belt. (Known) It is sectional drawing of the shoe press apparatus for paper manufacture. (Known) It is a figure explaining a Demacha type | formula similar bending test. It is a figure explaining a bending fatigue test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Press roll 2 Paper making shoe press belt 3 Felt 4 Wet paper 5 Shoe 6 Reinforcing fiber base material 2a Outer peripheral layer 2b Inner peripheral layer 21 Outer peripheral layer 22 Inner peripheral layer 24 Concave groove 25 Convex groove

Claims (3)

In a papermaking shoe press belt in which a reinforcing fiber base material and polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane, p-phenylene diisocyanate and polytetramethylene glycol are used as the polyurethane layer. Curing selected from urethane prepolymer (a) having an isocyanate group at the terminal obtained by reaction, 1,4-butanediol, hydroquinone bis-βhydroxylethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine A shoe press belt comprising a polyurethane layer obtained by curing a composition mixed with the agent (b).
(A) a urethane prepolymer having an isocyanate group at a terminal obtained by reacting an isocyanate compound (A) containing 55 to 100 mol% of a p-phenylene-diisocyanate compound with polytetramethylene glycol (B),
(B) A curing agent selected from 1,4-butanediol, hydroquinone bis-β hydroxyl ethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine.   In a shoe press belt for papermaking, in which a reinforcing fiber base material and polyurethane are integrated, and the reinforcing fiber base material is embedded in the polyurethane, an outer peripheral layer and an inner peripheral layer are formed of the polyurethane, forming an outer peripheral layer The polyurethane to be used is a urethane prepolymer (a) having an isocyanate group at the terminal obtained by reacting p-phenylene diisocyanate with polytetramethylene glycol, 1,4-butanediol, hydroquinone bis-β hydroxyl ethyl ether, A polyurethane obtained by curing a composition in which a curing agent (b) selected from 3,5-diethyltoluenediamine and dimethylthiotoluenediamine is mixed, and the polyurethane forming the inner peripheral layer is 2,4- Tolylene diisocyanate, 2,6-tolylene diisocyanate And a urethane prepolymer having an isocyanate group at the terminal obtained by reacting an isocyanate compound selected from 4,4'-methylenebis (phenylisocyanate) with polytetramethylene glycol, dimethylthiotoluenediamine, hydroquinonebis-β The reinforcing fiber base is formed from a polyurethane inner peripheral layer obtained by curing a composition in which a curing agent selected from hydroxyl ethyl ether, 3,5-diethyltoluenediamine and 1,4-butanediol is mixed. A shoe press belt embedded in the inner circumferential layer of the polyurethane.   Papermaking in which a reinforcing fiber base and a polyurethane layer are integrated, the reinforcing fiber base is embedded in the polyurethane intermediate layer, and an outer peripheral polyurethane layer and an inner peripheral polyurethane layer are laminated on both sides of the intermediate layer In the shoe press belt, the polyurethane forming the outer peripheral layer polyurethane layer and the inner peripheral layer polyurethane layer is a urethane prepolymer having an isocyanate group at the terminal obtained by reacting p-phenylene-diisocyanate with polytetramethylene glycol ( a composition obtained by mixing a) with a curing agent (b) selected from 1,4-butanediol, hydroquinone bis-βhydroxylethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine is cured. The intermediate layer is formed with polyurethane obtained by Polyurethane is an isocyanate at the end obtained by reacting an isocyanate compound selected from 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and 4,4′-methylenebis (phenyl isocyanate) with polytetramethylene glycol. From a polyurethane obtained by curing a composition in which a urethane prepolymer having a group and 1,4-butanediol, hydroquinonebis-βhydroxylethyl ether, 3,5-diethyltoluenediamine and dimethylthiotoluenediamine are mixed A formed shoe press belt.

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