JP2011031476A - Suction belt for conveying printing medium in inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suction belt for conveying a printing medium in an inkjet printer having excellent suction function and conveyance precision. <P>SOLUTION: The suction belt 1 for conveying a printing medium in an inkjet printer is so constituted that an elastic layer 3 is provided on one face or both faces of a base material 2 made of a polyimide resin and a plurality of suction holes 5 for suction are provided on the entire face. By providing the elastic layer 3 on the base material 2, a tearing strength of the belt is improved so that it is possible to provide the plurality of suction holes 5 on the whole face of the belt while preventing a crack from being generated around the suction hole 5 by an impact received in a drilling process. In addition, since the base material 2 is made of a polyimide resin, it is possible to obtain an excellent conveyance precision. It is preferable that the elastic layer 3 is made of an imide-modified elastomer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a suction belt used for conveying a print medium such as paper in an inkjet printer.

  In an ink jet printer, an ink jet head is disposed along a transport path formed by a transport belt, and printing is performed by ejecting ink from the ink jet head to a print medium such as paper.

  The print medium is transported to the inkjet head by the transport belt and printed while passing through the transport path. That is, in an inkjet printer, printing is performed by moving a print medium. For this reason, in the ink jet printer, the print medium is likely to be shifted or floated, and printing defects are likely to occur.

  There is a method of using a suction (suction) belt as the transport belt in order to suppress displacement and floating of the print medium (see, for example, Patent Document 1). The suction belt has a plurality of suction holes for suction on the entire surface. When a suction box having a plurality of air inlets is arranged below the suction belt and the inside of the box is set to a negative pressure, air on the belt surface is sucked into the box through the suction hole of the belt, A suction force is generated. Therefore, according to the suction belt, the print medium can be sucked and fixed on the belt surface, and the displacement and the floating of the print medium can be suppressed.

  As the suction belt, a material obtained by punching a canvas impregnated with a resin to form the suction hole is generally used. Recently, with the improvement in image quality of inkjet printers, the conveyance accuracy required for the suction belt has also increased.

  However, in the above-described conventional suction belt, since the canvas has elasticity, the conveyance accuracy is likely to vary, and the required conveyance accuracy cannot be met. In addition, when canvas is used, unevenness is generated on the belt surface due to uneven weaving, and printing accuracy deteriorates. Furthermore, if canvas is used, the belt must have a relatively large thickness, and this is also not suitable for precision conveyance applications.

  On the other hand, there is a belt made of polyimide resin as a belt that hardly causes variations in conveyance accuracy. If the suction hole is formed in this belt, it is considered that a suction belt having excellent conveyance accuracy can be obtained.

  However, since the polyimide resin has a high hardness, if the hole made on the belt made of the polyimide resin is subjected to the perforating process, a crack is generated around the suction hole due to the impact, and the crack propagates to the adjacent suction. There is a problem that the holes communicate with each other and the belt breaks.

JP 2007-130761 A

  An object of the present invention is to provide a suction belt for transporting a print medium of an ink jet printer having an excellent suction function and transport accuracy.

  As a result of intensive studies to solve the above problems, the present inventors have improved the tear strength of the belt when providing an elastic layer on one or both sides of a base material made of polyimide resin. The present inventors have found a new fact that it is possible to suppress the generation of cracks around the suction hole due to the impact received during the drilling process for forming the suction hole, and the present invention has been completed.

That is, the suction belt for conveying a print medium of the inkjet printer of the present invention is characterized in that an elastic layer is provided on one or both sides of a base material made of polyimide resin, and a plurality of suction holes for suction are provided on the entire surface. .
When the elastic layer is made of an imide-modified elastomer, the affinity with a base material made of a polyimide resin is increased.
In addition, the said "imide modified elastomer" in this invention means the elastomer which has an imide component, and is a concept also including resin by the ratio (imide fraction) of the said imide component.

  According to the present invention, an elastic layer is provided on at least one side of a base material made of polyimide resin, so that the tear strength of the belt can be improved, so that a crack is generated around the suction hole due to an impact received during drilling. While suppressing this, a plurality of suction holes can be provided on the entire belt surface, and therefore an excellent suction function can be obtained. And since a base material consists of polyimide resins, the outstanding conveyance precision can also be obtained. Therefore, according to the present invention, it is possible to achieve both the suction function and the conveyance accuracy.

  In particular, when the elastic layer is made of an imide-modified elastomer, the affinity with a base material made of a polyimide resin is increased, so that it is possible to suppress a decrease in durability due to peeling of both.

It is a partial top view which shows the suction belt for printing-medium conveyance of the inkjet printer concerning one Embodiment of this invention. It is an AA line expanded sectional view of FIG.

  Hereinafter, an embodiment of a suction belt for conveying a print medium of an ink jet printer according to the present invention will be described in detail with reference to FIGS. 1 and 2 by taking as an example a case where an elastic layer is made of an imide-modified elastomer.

  As shown in FIGS. 1 and 2, a suction belt 1 according to this embodiment includes a base material 2 and an elastic layer 3 provided on one surface of the base material 2, and suction holes for suction are formed on the entire surface. A plurality of 5 are provided.

  The base material 2 consists of a polyimide resin. The polyimide resin has characteristics such as high strength and low relaxation characteristics due to its structure, and these characteristics are suitable for belt materials used in applications that require precision rotation. Therefore, when the polyimide resin is used for the base material 2, the polyimide resin functions as a tension holder having a low elongation and a high strength, so that the suction belt 1 can be precisely driven and excellent conveyance accuracy can be obtained. .

  The polyimide resin can be obtained, for example, by imidizing polyamic acid synthesized from an acid anhydride and a diamine compound with heat or a catalyst. Examples of the acid anhydride include pyromellitic anhydride, oxydiphthalic dianhydride, biphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, benzophenone-3,4,3 ′, 4′- Tetracarboxylic dianhydride, diphenylsulfone-3,4,3 ′, 4′-tetracarboxylic dianhydride, 4,4 ′-(2,2′-hexafluoroisopropyridin) diphthalic dianhydride, cyclobutane Aromatic tetracarboxylic dianhydrides such as -1,2,3,4-tetracarboxylic dianhydride and the like. Examples of the diamine compound include 1,4-diaminobenzene and 1,3-diaminobenzene. 2,4-diaminotoluene, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3 -Dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,7-diamino-dimethyldibenzothiophene-5,5'-dioxide, 4, Examples include aromatic diamines such as 4′-diaminobenzophenone, 4,4′-bis (4-aminophenyl) sulfide, 4,4′-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, and the like. . As such a polyimide resin, for example, those described in Japanese Patent No. 2560727 can be employed. The polyimide resin is preferably thermosetting.

  The thickness of the substrate 2 is 40 to 120 μm, preferably 70 to 90 μm. If the thickness of the substrate 2 is too thin, it is difficult to obtain the effect of the polyimide resin, and the conveyance accuracy of the suction belt 1 may be reduced. Moreover, when the thickness of the base material 2 is too large, the influence by the high hardness which a polyimide resin has becomes large, and there exists a possibility that a crack may generate | occur | produce by the deformation | transformation in a pulley bending part.

  On the other hand, the elastic layer 3 is made of an imide-modified elastomer. When this elastic layer 3 is provided on one side of the substrate 2, the tear strength of the suction belt 1 is improved. This is presumably because the influence of the high hardness of the polyimide resin is mitigated by the elastic force of the elastic layer 3 and the flexibility of the suction belt 1 is improved. Therefore, when the elastic layer 3 is provided on one surface of the base material 2, it is possible to suppress the generation of cracks around the suction holes 5 due to the impact received during the drilling process for forming the suction holes 5. Moreover, since the elastic layer 3 made of an imide-modified elastomer is excellent in affinity with the base material 2 made of a polyimide resin, it is possible to suppress a decrease in durability due to peeling of both.

  The imide-modified elastomer preferably has the following elastomer component and imide component in the elastomer. That is, examples of the elastomer component include polyurethanes, unsaturated olefin oligomers, acrylic oligomers, fluororubber oligomers, and silicone oligomers. Examples of the imide components include alicyclic monomers and heterocyclic monomers. , Phenyl ether monomers, alkyl side chain monomers, and the like.

  The imide-modified elastomer will be described in more detail by taking an imide-modified polyurethane elastomer (hereinafter referred to as “PIUE”) having polyurethane as an elastomer component as an example. Examples of PIUE include PIUE represented by the following general formula (I) (hereinafter referred to as “PIUE (I)”).

［式中、Ｒ₁は、芳香族環または脂肪族環を含む２価の有機基を示す。Ｒ₂は、重量平均分子量１００〜１０，０００の２価の有機基を示す。Ｒ₃は、芳香族環、脂肪族環または脂肪族鎖を含む２価の有機基を示す。Ｒ₄は、４個以上の炭素を含む４価の有機基を示す。ｎは１〜１００の整数を示す。ｍは２〜１００の整数を示す。］

[Wherein, R ₁ represents a divalent organic group containing an aromatic ring or an aliphatic ring. R ₂ represents a divalent organic group having a weight average molecular weight of 100 to 10,000. R ₃ represents a divalent organic group containing an aromatic ring, an aliphatic ring or an aliphatic chain. R ₄ represents a tetravalent organic group containing 4 or more carbon atoms. n shows the integer of 1-100. m shows the integer of 2-100. ]

In the general formula (I), R ₁ represents a divalent organic group containing an aromatic ring or an aliphatic ring. Examples of the organic group include a polyol (according to the reaction process formula (A) described later) Residues other than the isocyanate group (—NCO) in the diisocyanate (a) that can form the urethane prepolymer (c) together with b) are exemplified.

R ₂ represents a divalent organic group having a weight average molecular weight of 100 to 10,000, preferably 300 to 5,000. Examples of the organic group include diisocyanate according to the reaction process formula (A). Examples of the polyol (b) that can form a urethane prepolymer (c) together with (a) include residues other than two hydroxyl groups (—OH).

R ₃ represents a divalent organic group containing an aromatic ring, an aliphatic ring, or an aliphatic chain. Examples of the organic group include urethane prepolymers (c) according to a reaction process formula (B) described later. ) At least one diamine selected from aromatic diamine compounds having 6 to 27 carbon atoms, aliphatic diamine compounds having 6 to 24 carbon atoms and alicyclic diamine compounds having 6 to 24 carbon atoms Examples of the compound (d) include a residue excluding an amino group (—NH ₂ ). The aliphatic chain includes one having 1 carbon.

R ₄ represents a tetravalent organic group containing 4 or more carbons, and examples of the organic group include carbon capable of introducing an imide unit into a urea bond portion according to a reaction process formula (C) described later, for example. A residue of at least one tetracarboxylic dianhydride (f) selected from an aromatic tetracarboxylic dianhydride having 6 to 18 carbon atoms and an alicyclic tetracarboxylic dianhydride having 4 to 6 carbon atoms; Can be mentioned.
n represents an integer of 1 to 100, preferably 2 to 50. m represents an integer of 2 to 100, preferably 2 to 50.

［式中、ｎは１〜１００の整数を示す。ｍは２〜１００の整数を示す。ｘは１０〜１００の整数を示す。］ Specific examples of PIUE (I) include PIUE represented by the following formula (1).

[Wherein n represents an integer of 1 to 100. m shows the integer of 2-100. x shows the integer of 10-100. ]

  PIUE (I) is a urethane prepolymer obtained from diisocyanate and polyol and having an isocyanate group at both ends of the molecule. The urethane prepolymer is chain-extended with a diamine compound by a urea bond, and an imide unit is formed at the urea bond with tetracarboxylic dianhydride. The introduced block copolymer is preferable. Such PIUE (I) can be produced through reaction process formulas (A) to (C) as shown below, for example.

［式中、Ｒ₁，Ｒ₂，ｎは、前記と同じである。］ [Reaction process formula (A)]

[Wherein R ₁ , R ₂ and n are the same as described above. ]

(Synthesis of urethane prepolymer (c))
As shown in the reaction process formula (A), first, a urethane prepolymer (c) having an isocyanate group at both molecular ends is obtained from the diisocyanate (a) and the polyol (b). Since PIUE (I) uses this urethane prepolymer (c) as an elastomer component, the elastic modulus of the rubber-like region (near room temperature) is lowered, and the urethane prepolymer (c) can be made more elastic. ), The two imide units continuous in the main chain can be introduced at a desired ratio while controlling the distribution thereof.

  Examples of the diisocyanate (a) include 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), and polymeric MDI. (Cr.MDI), dianisidine diisocyanate (DADL), diphenyl ether diisocyanate (PEDI), pitorylene diisocyanate (TODI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HMDI), isophorone Isocyanate (IPDI), lysine diisocyanate methyl ester (LDI), metaxylylene diisocyanate (MXDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), 2,4,4-trimethylhexamethylene Isocyanate (TMDI), dimer acid diisocyanate (DDI), isopropylidenebis (4-cyclohexyl isocyanate) (IPCI), cyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate (hydrogenated TDI) , TDI dimer (TT), and the like. These may be used alone or in combination of two or more, and those distilled under reduced pressure are preferably used.

  Examples of the polyol (b) include polyether polyols such as polypropylene glycol (PPG), polyoxytetramethylene glycol (PTMG), and polymer polyol; polyester polyols such as adipate-based polyol (condensed polyester polyol) and polycaprolactone-based polyol; Polycarbonate polyols; polybutadiene polyols; acrylic polyols and the like may be mentioned, and these may be used alone or in combination of two or more.

  The polyol (b) is preferably used after being dried under reduced pressure under conditions of 70 to 90 ° C., 1 to 5 mmHg, and 10 to 30 hours. The weight average molecular weight of the polyol (b) is 100 to 10,000, preferably 300 to 5,000. The weight average molecular weight is a value obtained by measuring the polyol (b) by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  The reaction is performed by mixing the diisocyanate (a) and polyol (b) exemplified above at a predetermined ratio, and then reacting at room temperature to 100 ° C. for about 1 hour to 5 hours in an inert gas atmosphere such as argon gas. You can do it. The mixing ratio (mole) of diisocyanate (a) and polyol (b) is within the range of diisocyanate (a): polyol (b) = 1.1: 1.0 to 2.0: 1.0. It is preferable to do this.

  The weight average molecular weight of the urethane prepolymer (c) to be obtained is 300 to 50,000, preferably 500 to 47,000. If the molecular weight is too small, PIUE (I) becomes too hard and flexibility may be reduced. On the other hand, if the molecular weight is too large, PIUE (I) becomes too soft and the strength may be lowered. The weight average molecular weight is a value obtained by measuring the urethane prepolymer (c) by GPC and converting the obtained measurement value into polystyrene.

［式中、Ｒ₁〜Ｒ₃，ｎ，ｍは、前記と同じである。］ [Reaction process formula (B)]

[Wherein, R _{1 to} R ₃ , n, m are the same as described above. ]

(Synthesis of polyurethane-urea compound (e))
Using the urethane prepolymer (c) obtained above, a polyurethane-urea compound (e), which is an imide precursor, is synthesized according to the reaction process formula (B). That is, the urethane prepolymer (c) is chain-extended by a urea bond with the diamine compound (d) to obtain a polyurethane-urea compound (e).

  Examples of the diamine compound (d) include 1,4-diaminobenzene (alias: p-phenylenediamine, abbreviation: PPD), 1,3-diaminobenzene (alias: m-phenylenediamine, abbreviation: MPD), 2, 4-diaminotoluene (alias: 2,4-toluenediamine, abbreviation: 2,4-TDA), 4,4′-diaminodiphenylmethane (alias: 4,4′-methylenedianiline, abbreviation: MDA), 4,4 '-Diaminodiphenyl ether (alias: 4,4'-oxydianiline, abbreviation: ODA, DPE), 3,4'-diaminodiphenyl ether (alias: 3,4'-oxydianiline, abbreviation: 3,4'-DPE) ), 3,3′-dimethyl-4,4′-diaminobiphenyl (also known as o-tolidine, abbreviated as TB), 2,2′-dimethyl-4,4′-dia Nobiphenyl (alias: m-tolidine, abbreviation: m-TB), 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (abbreviation: TFMB), 3,7-diamino-dimethyldibenzothiophene -5,5-dioxide (alias: o-tolidine sulfone, abbreviation: TSN), 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-bis (4-aminophenyl) sulfide (alias : 4,4'-thiodianiline, abbreviation: ASD), 4,4'-diaminodiphenylsulfone (also known as 4,4'-sulfonyldianiline, abbreviation: ASN), 4,4'-diaminobenzanilide (abbreviation: DABA) ), 1, n-bis (4-aminophenoxy) alkane (n = 3,4,5, abbreviation: DAnMG), 1,3-bis (4-aminophen) Noxy) -2,2-dimethylpropane (abbreviation: DANPG), 1,2-bis [2- (4-aminophenoxy) ethoxy] ethane (abbreviation: DA3EG), 9,9-bis (4-aminophenyl) fluorene (Abbreviation: FDA), 5 (6) -amino-1- (4-aminomethyl) -1,3,3-trimethylindane, 1,4-bis (4-aminophenoxy) benzene (abbreviation: TPE-Q) 1,3-bis (4-aminophenoxy) benzene (alias: resorcinoxydianiline, abbreviation: TPE-R), 1,3-bis (3-aminophenoxy) benzene (abbreviation: APB), 4,4 ′ -Bis (4-aminophenoxy) biphenyl (abbreviation: BAPB), 4,4'-bis (3-aminophenoxy) biphenyl, 2,2-bis (4-aminophenoxyphenyl) propyl Lopan (abbreviation: BAPP), bis [4- (4-aminophenoxy) phenyl] sulfone (abbreviation: BAPS), bis [4- (3-aminophenoxy) phenyl] sulfone (abbreviation: BAPS-M), 2,2 -Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (abbreviation: HFBAPP), 3,3′-dicarboxy-4,4′-diaminodiphenylmethane (abbreviation: MBAA), 4,6-dihydroxy-1 , 3-phenylenediamine (alias: 4,6-diaminoresorcin), 3,3′-dihydroxy-4,4′-diaminobiphenyl (alias: 3,3′-dihydroxybenzidine, abbreviation: HAB), 3,3 ′ , 4,4′-tetraaminobiphenyl (also known as: 3,3′-diaminobenzidine, abbreviation: TAB) and other aromatics having 6 to 27 carbon atoms Amine compounds; 1,6-hexamethylenediamine (HMDA), 1,8-octamethylenediamine (OMDA), 1,9-nonamethylenediamine, 1,12-dodecamethylenediamine (DMDA), 1-amino-3- C6-C24 aliphatic or cycloaliphatic diamine compounds such as aminomethyl-3,5,5-trimethylcyclohexane (also known as isophoronediamine), 4,4'-dicyclohexylmethanediamine, cyclohexanediamine; Examples thereof include silicone-based diamine compounds such as bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, and these may be used alone or in combination.

In the reaction, the urethane prepolymer (c) and the diamine compound (d) exemplified above are mixed in an equimolar amount, preferably an NCO / NH ₂ ratio of about 1.0, and then inert such as argon gas. What is necessary is just to perform a solution polymerization reaction or a block polymerization reaction in a gas atmosphere at room temperature to 100 ° C. for about 2 to 30 hours.

  Examples of the solvent that can be used for the solution polymerization reaction include N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-hexyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidone, and the like. In particular, N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-hexyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidone are preferable. These solvents may be used singly or in combination of two or more, and it is preferable to use a solvent that has been dehydrated according to a conventional method.

［式中、Ｒ₁〜Ｒ₄，ｎ，ｍは、前記と同じである。］ [Reaction process formula (C)]

[Wherein, R _{1 to} R ₄ , n, m are the same as described above. ]

(Synthesis of PIUE (I))
Using the polyurethane-urea compound (e) obtained above, PIUE (I) is synthesized according to the reaction process formula (C). That is, the imide unit is introduced into the urea bond portion with tetracarboxylic dianhydride (f) to obtain PIUE (I) which is a block copolymer.

  Examples of the tetracarboxylic dianhydride (f) include pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), biphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride ( BPDA), benzophenone-3,4,3 ′, 4′-tetracarboxylic dianhydride (BTDA), diphenylsulfone-3,4,3 ′, 4′-tetracarboxylic dianhydride (DSDA), 4, Carbon number of 4 ′-(2,2-hexafluoroisopropylidene) diphthalic dianhydride (6FDA), m (p) -terphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, etc. 6-18 aromatic tetracarboxylic dianhydrides; cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid- , 6: 3,5 dianhydride alicyclic tetracarboxylic dianhydride of 4-6 carbon atoms such as, and the like. These may be used alone or in combination.

  The reaction is an imidization reaction between the polyurethane-urea compound (e) and the tetracarboxylic dianhydride (f). The imidation reaction may be performed in a solvent or without a solvent. When the imidization reaction is performed in a solvent, first, the polyurethane-urea compound (e) and the tetracarboxylic dianhydride (f) exemplified above are added to the solvent at a predetermined ratio, and an argon gas or the like is added. Under an inert gas atmosphere, the reaction is carried out at 100 to 300 ° C., preferably 135 to 200 ° C., more preferably 150 to 170 ° C. for about 1 hour to 10 hours, and polyurethane amic acid represented by the following formula (g) ( A solution containing PUA) (PUA solution) is obtained.

［式中、Ｒ₁〜Ｒ₄，ｎ，ｍは、前記と同じである。］

[Wherein, R _{1 to} R ₄ , n, m are the same as described above. ]

  Here, the mixing of the polyurethane-urea compound (e) and the tetracarboxylic dianhydride (f) is carried out by mixing the diamine compound (d) and tetracarboxylic dianhydride used in the synthesis of the polyurethane-urea compound (e) ( It is preferable that the mixing ratio (mol) with f) is mixed in such a ratio that the ratio of diamine compound (d): tetracarboxylic dianhydride (f) = 1: 2 to 1: 2.02. Thereby, an imide unit can be reliably introduced into the urea bond portion.

  Examples of the solvent that can be used include the same solvents as those exemplified as the solvent that can be used in the solution polymerization reaction of the reaction process formula (B). In the reaction process formula (B), when the polyurethane-urea compound (e) is obtained by a solution polymerization reaction, an imidization reaction may be performed in the solvent.

  Next, the PUA solution obtained above is heat-treated at 100 to 200 ° C. for 60 to 120 minutes, and further subjected to heat treatment (dehydration condensation reaction) to obtain PIUE (I). The heat treatment is a condition in which PUA is not thermally decomposed, and is preferably performed at 150 to 250 ° C. for 90 to 150 minutes.

  On the other hand, when the imidization reaction is carried out in the absence of a solvent, it can be carried out in an extruder equipped with a heating means having an exhaust system in addition to a normal stirred tank reactor, so that the resulting PIUE (I) Can be extruded and formed into a film as it is.

  PIUE (I) obtained as described above has a glass transition temperature (Tg) of usually −30 to −60 ° C., high elasticity, and a wide temperature range of the rubber-like elastic region. become. The following reason is guessed as this reason. That is, since PIUE (I) can introduce two imide units continuous in the main chain at a desired ratio (imide fraction) while controlling the distribution, aggregation of hard segments composed of the imide units is prevented. It becomes uniform and strong. For this reason, PIUE (I) forms a more uniform and strong microphase separation structure, and the glass transition temperature is lowered, thereby widening the temperature range of the rubber-like elastic region.

  The weight average molecular weight of PIUE (I) is 10,000 to 1,000,000, preferably 30,000 to 800,000, more preferably 30,000 to 500,000. The weight average molecular weight is a value derived from a value obtained by measuring the PUA solution by GPC and converting the obtained measurement value into polystyrene. The reason why PUA solution, not PIUE (I), is measured by GPC is that PIUE (I) is insoluble in the GPC measurement solvent.

  PIUE (I) can adjust the elastic modulus by adjusting the imide fraction (imide component content), that is, the ratio of the imide component in the imide-modified elastomer. The imide fraction may be arbitrarily selected according to the elastic modulus and the like, and is not particularly limited, but is usually 25% by weight or less, preferably 15% by weight or less. Usually, 5% by weight or more is appropriate. The imide fraction is a value calculated from the charged amounts of raw materials, that is, diisocyanate (a), polyol (b), diamine compound (d) and tetracarboxylic dianhydride (f), and more specifically. Is a value calculated from the following formula (α).

The elastic modulus adjusted by the imide fraction is preferably about 1.0 × 10 ^{6 to} 1.0 × 10 ⁹ Pa. The elastic modulus is a value of the storage elastic modulus E ′ at 50 ° C. obtained by measurement using a dynamic viscoelasticity measuring apparatus.

  The elastic layer 3 has a thickness of 10 to 70 μm, preferably 30 to 50 μm. If the elastic layer 3 is too thin, it is difficult to improve the tear strength of the suction belt 1, which is not preferable. Further, if the thickness of the elastic layer 3 is too large, the total thickness of the belt is increased, which adversely affects the flexibility and the like.

  As shown in FIG. 2, the suction hole 5 is a through-hole penetrating the base material 2 and the elastic layer 3. Moreover, as shown in FIG. 1, the diameter D of the suction hole 5 is 1 to 10 mm, preferably 1 to 5 mm. The distance L between the suction holes 5 and 5 adjacent to each other is 5 to 20 mm, preferably 5 to 15 mm. The interval L is the distance from the center of one adjacent suction hole 5 to the center of the other suction hole 5. In addition, the diameter D and the space | interval L of the suction hole 5 are not limited to the numerical range mentioned above, It can adjust arbitrarily so that a desired suction function may be obtained according to a printing medium.

  Next, the manufacturing method of the suction belt 1 will be described by taking the case of using the above-described PIUE (I) as an imide-modified elastomer as an example. In addition, if the suction belt 1 is used in a seamless form, the conveyance accuracy is improved. Therefore, the manufacturing method of the seamless suction belt 1 which makes the base material 2 the surface layer and makes the elastic layer 3 the back layer is demonstrated.

  The seamless suction belt 1 can be obtained by, for example, a centrifugal molding method. First, a polyamic acid solution that is a precursor of a polyimide resin and the PUA solution described above are prepared. The polyamic acid solution is not particularly limited, and a commercially available product may be used in addition to the polyamic acid added to an appropriate solvent. Specific examples include the product name “Ube Industries, Ltd.” U varnish A "and the like are preferred.

  Next, the polyamic acid solution is subjected to centrifugal molding at 100 to 150 ° C. and 100 to 400 rpm for 60 to 120 minutes using a centrifugal molding machine to obtain a cylindrical polyamic acid sheet. The molding drum containing the polyamic acid sheet is removed from the centrifugal molding machine, and the polyamic acid sheet is put into a heat oven together with the molding drum, and subjected to heat treatment at 300 to 350 ° C. for 30 to 90 minutes. To obtain (ie substrate 2).

  The obtained polyimide resin sheet is returned to the centrifugal molding machine together with the molding drum, a PUA solution is poured into the inner surface of the molding drum, and centrifugal molding is performed at 100 to 200 ° C. and 100 to 300 rpm for 60 to 120 minutes to form a cylindrical laminate. Get a sheet.

  The obtained laminated sheet is put into a heating oven together with the forming drum and subjected to heat treatment at 150 to 250 ° C. for 90 to 150 minutes, thereby making the base material 2 a surface layer and the elastic layer 3 a back layer. Get a belt. If a PUA solution and a polyamic acid solution are poured into a centrifugal molding machine in this order, a seamless belt having the elastic layer 3 as a surface layer and the base material 2 as a back layer can be obtained.

  Finally, the seamless belt is drilled to obtain the suction belt 1. At this time, since the elastic layer 3 is provided on one surface of the base material 2, the tear strength of the belt is improved, so that a crack is generated around the suction hole 5 due to an impact received during drilling. A plurality of suction holes 5 can be provided on the entire surface of the belt while being suppressed. The drilling can be performed, for example, by punching with a jig provided with a blade corresponding to the shape of the suction hole 5.

  The obtained suction belt 1 can be used for conveying a print medium of an ink jet printer. As a specific example, first, a suction belt 1 is stretched between a driving pulley and a driven pulley provided in an ink jet printer to form a conveyance path. At this time, it is preferable that the suction belt 1 is stretched so that the elastic layer 3 contacts the driving pulley and the driven pulley. The reason for this is that, usually, the surface friction coefficient (μ) of the elastic layer 3 is larger than the surface friction coefficient (μ) of the base material 2 and is received from the pulley when the elastic layer 3 is brought into contact with each pulley. This is because the power is efficiently transmitted to the suction belt 1.

  Next, a suction box having a plurality of air inlets is disposed below the suction belt 1. When the inside of the box is set to a negative pressure, air on the surface of the suction belt 1 is sucked into the box through the suction holes 5 and a suction force is generated on the surface of the suction belt 1. As a result, a print medium such as paper can be sucked and fixed onto the surface of the suction belt 1, and the print medium can be conveyed to an inkjet head arranged along the conveyance path while suppressing displacement and floating of the print medium. Printing can be performed. Therefore, according to the suction belt 1, it is possible to suppress the occurrence of printing defects due to the printing medium being displaced or floating.

As mentioned above, although preferred embodiment concerning this invention was shown, this invention is not limited to the above embodiment, A various improvement and change are possible within the range as described in a claim. For example, in the above-described embodiment, the case where the elastic layer is made of an imide-modified elastomer has been described as an example, but the present invention is not limited to this. That is, examples of the material constituting the elastic layer according to the present invention include thermoplastic elastomers such as polyurethane elastomers and polyester elastomers, as well as imide-modified elastomers; natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, and ethylene propylene rubber. , Rubbers such as chloroprene rubber, epichlorohydrin rubber, nitrile rubber, acrylic rubber, acrylonitrile-butadiene rubber, urethane rubber, H-NBR (hydrogenated nitrile butadiene rubber), and the like. May be used. The elastic modulus of the elastic layer made of these exemplified materials is preferably about 1.0 × 10 ^{6 to} 1.0 × 10 ⁹ Pa.

  When the elastic layer is made of an imide-modified elastomer, it has a high affinity with a base material made of polyimide resin, so that the elastic layer and the base material can be integrally formed without performing an adhesive treatment with an adhesive. Although it is possible, when an elastic layer consists of the material illustrated above, an elastic layer can be laminated | stacked on a base material by performing an adhesion | attachment process as needed.

  Moreover, you may provide an elastic layer in both surfaces of a base material. Thereby, the elastic layer having a large surface friction coefficient (μ) comes into contact with the print medium, so that the transportability of the print medium can be improved.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples.

［式中、ｎは１〜１００の整数を示す。ｍは２〜１００の整数を示す。ｘは５〜１００の整数を示す。］ <Synthesis example>
A PUA solution was synthesized based on the following formula.

[Wherein n represents an integer of 1 to 100. m shows the integer of 2-100. x shows the integer of 5-100. ]

(Synthesis of urethane prepolymer (j))
First, 4,4′-diphenylmethane diisocyanate (MDI) (h) [manufactured by Nippon Polyurethane Industry Co., Ltd.] was distilled under reduced pressure. Also, polyoxytetramethylene glycol (PTMG) (i) [trade name “PTMG1000” manufactured by Hodogaya Chemical Co., Ltd., weight average molecular weight: 1,000] under the conditions of 80 ° C., 2-3 mmHg, 24 hours. It was dried under reduced pressure.

Next, 23.8 g of the above MDI (h) and 76.2 g of PTMG (i) were added to a 500 ml four-necked separable flask equipped with a stirrer and a gas introduction tube, respectively, and 2 at 80 ° C. under an argon atmosphere. The mixture was stirred for a time to obtain a urethane prepolymer (j) having isocyanato groups at both molecular ends. As a result of measuring this urethane prepolymer (j) by GPC, the weight average molecular weight was 4.6 × 10 ⁴ in terms of polystyrene.

(Synthesis of polyurethane-urea compound (l))
10 g of the urethane prepolymer (j) obtained above was dissolved in 60 ml of dehydrated N-methyl-2-pyrrolidone (NMP), and 0.378 g of 4,4′-diaminodiphenylmethane (MDA) (k). What was dissolved in 20 ml of dehydrated NMP was added to a 500 ml four-necked separable flask equipped with a stirrer and a gas introduction tube, respectively, and stirred at room temperature (23 ° C.) for 24 hours under an argon atmosphere. A solution of the urea compound (l) was obtained.

(Synthesis of PUA solution)
To the solution of the polyurethane-urea compound (l) obtained above, 0.831 g of pyromellitic anhydride (PMDA) (m) is added and stirred at 150 ° C. for 2 hours under an argon gas atmosphere to obtain a PUA solution. It was.

  The PUA solution is poured into a centrifugal molding machine and centrifuged at 150 ° C. and 1,000 rpm for 60 minutes to obtain a PUA sheet. The PUA sheet is heated in a vacuum desiccator at 200 ° C. for 120 minutes (dehydration condensation reaction). As a result, a sheet-like PIUE (1) having a thickness of 100 μm was obtained.

The obtained PIUE (1) had an imide fraction of 25% by weight, an elastic modulus of 4.9 × 10 ⁷ Pa, and a weight average molecular weight of 37,000. The imide fraction was calculated from the formula (α). The elastic modulus is 50 Hz in a temperature rising process of 10 Hz, 5 ° C./min, −100 to 400 ° C. using a dynamic viscoelasticity measuring device “DMS 6100” manufactured by Seiko Instruments Inc. The storage elastic modulus E ′ at 0 ° C. was measured. The weight average molecular weight was derived from a value obtained by measuring the PUA solution by GPC and converting the obtained measurement value into polystyrene.

Further, the obtained PIUE (1), a result of measuring the IR spectrum at ATR method, 1780 cm ^-1, absorption derived from the imide ring to 1720 cm ^-1 and 1380 cm ^-1 were observed.

<Production of suction belt>
First, a polyamic acid solution (trade name “U Varnish A” manufactured by Ube Industries Co., Ltd.) was subjected to centrifugal molding at 120 ° C. and 286 rpm for 90 minutes using a centrifugal molding machine to obtain a cylindrical polyamic acid sheet. It was. Next, the molding drum containing the polyamic acid sheet is removed from the centrifugal molding machine, and the polyamic acid sheet is put together with the molding drum into a heat oven, heated at 320 ° C. for 60 minutes, and a polyimide resin sheet having a thickness of 80 μm is obtained. Obtained.

  The obtained polyimide resin sheet is returned to the centrifugal molding machine together with the molding drum, the PUA solution obtained in the above synthesis example is injected into the molding drum inner surface, and centrifugal molding is performed at 120 ° C. and 165 rpm for 90 minutes to form a cylindrical shape having a thickness of 120 μm. A laminated sheet was obtained.

The obtained laminated sheet was put into a heat oven together with the forming drum and subjected to a heat treatment at 200 ° C. for 120 minutes to obtain a seamless laminated belt having a thickness of 120 μm and having a layer structure shown below.
Surface layer: base material 80 μm thick made of polyimide resin Back layer: elastic layer 40 μm thick made of imide-modified elastomer (PIUE (1))

Finally, a hole was formed on the entire surface of the seamless laminated belt to obtain a suction belt. The perforating process was performed by punching with a jig provided with a blade body capable of forming through-holes with a diameter of 3 mm at intervals of 9 mm. As a result, the following suction holes could be formed without generating cracks around the suction holes due to the impact received during drilling.
Diameter of suction hole: 3mm
Spacing between adjacent suction holes: 9 mm

<Evaluation>
The tear strength in accordance with JIS K7128-1 was evaluated for the belt before drilling, that is, the seamless laminated belt. First, the seamless laminated belt was punched into a strip shape to obtain a test piece having a width of 15 mm and a length of 100 mm. Next, a cut having a length of 40 mm was made at the center of one end of the test piece to form a pair of grips. Of the pair of gripping portions, one was gripped by the upper chuck of the tensile tester and the other was gripped by the lower chuck, and the load was measured by pulling up and down at a tension speed of 50 mm / min. And tear strength (mN / mm) was computed from the obtained load. The results are shown in Table 1.

[Comparative example]
A polyamic acid sheet was obtained in the same manner as in the above example, and the polyamic acid sheet was heat-treated in the same manner as in the above example to obtain a seamless single layer belt made of a polyimide resin sheet having a thickness of 80 μm.

  Drilling was performed on the entire surface of the obtained seamless single layer belt in the same manner as in the above example. As a result, cracks and crests were generated around the suction holes due to the impact received during drilling. Further, the crack propagated and adjacent suction holes communicated with each other, and the belt was broken. The tear strength of the seamless single layer belt was evaluated in the same manner as in the above example. The results are shown in Table 1.

  As is apparent from Table 1, it can be seen that the tear strength is significantly improved in the Examples as compared with the Comparative Examples.

1 Suction belt 2 Base material 3 Elastic layer 5 Suction hole

Claims (2)

  A suction belt for conveying a print medium of an ink jet printer, characterized in that an elastic layer is provided on one or both sides of a base material made of polyimide resin, and a plurality of suction holes for suction are provided on the entire surface.   The suction belt according to claim 1, wherein the elastic layer is made of an imide-modified elastomer.

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