JP5477043B2 - Polyurethane elastomer composition and squeegee for screen printing - Google Patents

Description

  The present invention relates to a polyurethane elastomer composition and a squeegee for screen printing using the same. More specifically, the present invention relates to a polyurethane elastomer composition excellent in handling property and moldability during production because the polyester polyol used is kept in a liquid state at room temperature. The present invention also relates to a squeegee for screen printing that has improved elastomer characteristics (especially rebound resilience) while maintaining good solvent resistance of polyurethane elastomer, and enables precise and precise printing in screen printing.

  Screen printing, for example, is widely used for printing on posters, printed wiring, clothing prints, ceramics and glass products, metals, plastic products, etc. Is a method of printing ink on the surface to be printed through a screen with a tool called "."

  In general, "squeegee" is a rubber plate that presses and slides on the screen and pushes ink onto the surface to be printed. Usually, it is fixed with a holder so that it has a predetermined angle on the surface to be printed. Used. Therefore, the material, shape, hardness, and the like of this squeegee have a substantial influence on the characteristics of the squeegee and, in turn, have an important influence on the printing characteristics.

  Conventionally, squeegees have been manufactured from, for example, polyurethane elastomers, silicone rubbers, chloroprene rubbers, butadiene rubbers, etc. Among them, polyurethane elastomers are widely used because they are excellent in mechanical strength, wear resistance and the like. However, there was a problem that the solvent resistance was still insufficient.

  The screen printing method using a squeegee is used, for example, in the manufacture of electrical / electronic components, printing cream solder on printed wiring boards for ICs and LSIs, and various circuits including hybrid ICs and ceramic multilayer boards. Widely used in advanced and precise printing fields such as thick coating printing of conductive inks in the manufacture of substrates and various electronic components.

  In recent years, with the miniaturization and complexity of electronic devices, high-density mounting of components such as printed wiring boards has been increasingly required, and the amount of cream solder used for fixing components has become smaller. . Therefore, stabilization of the printing pressure on the squeegee substrate is an extremely important factor in completing high-precision mounting using a small amount of cream solder and completing a precise and precise printing finish.

  However, conventional polyurethane elastomer compositions are inferior in handling and moldability during production, and screen printing squeegees using them are inferior in solvent resistance and rebound resilience, resulting in unstable printing pressure and precision. There was a problem that it was not suitable for elaborate printing.

  In order to improve such a problem, various proposals have been made so far.

For example, in a squeegee for screen printing in which ink on a screen is copied onto a substrate, polyester and polyisocyanate by polymerization of ethylene glycol and a dicarboxylic acid having a structural formula of HOOC (CH ₂ ) _m COOH (m is an integer of 3 or less) There is known a screen printing squeegee made of urethane rubber obtained by reaction curing. Such screen printing squeegees have good mechanical properties, abrasion resistance, and ink-containing solvent resistance (see Patent Document 1).

  However, the squeegee for screen printing described in Patent Document 1 is inferior in rebound resilience, and has a problem that it cannot satisfy the printing characteristics required for precise and precise printing in screen printing.

  In particular, polyester polyols obtained by reacting ethylene glycol and succinic acid have very high polarity, so that the microbrown motion of the molecular chain of the obtained polyurethane elastomer (polyurethane resin) is inhibited, resulting in poor low temperature characteristics. Therefore, the squeegee using the polyurethane elastomer has a so-called “hard core phenomenon” in which the core hardness becomes too high under a low temperature condition to deteriorate the mechanical properties, and the printing characteristics can be kept constant. There was a problem that became difficult.

In addition, in a squeegee for screen printing in which the ink on the screen is copied onto the printing material, a lactone using a polyester obtained by condensation polymerization of HOOC (CH ₂ ) _m COOH (m is an integer of 3 or less) and ethylene glycol as a polymerization initiator. A squeegee for screen printing using urethane rubber obtained by reacting polyester with polyisocyanate and a curing agent is known. Such a squeegee for screen printing is resistant to various solvents, has good wear resistance, is highly elastic, and can be printed stably over a long period of time (see Patent Document 2).

  However, the squeegee for screen printing described in Patent Document 2 is also inferior in resilience like Patent Document 1, and has a problem that it cannot satisfy printing characteristics required for precise and precise printing in screen printing. Further, there has been a problem that it is difficult to keep the printing characteristics constant by causing the hard core phenomenon as described above under a low temperature condition.

  Also known is a squeegee for screen printing in which a urethane prepolymer obtained from a polyol comprising 10 to 90% by weight of polyethylene adipate polyol and 90 to 10% by weight of a lactone ester polyol and a polyisocyanate is cured with a curing agent. ing. Such a screen printing squeegee has improved low-temperature properties while maintaining good solvent resistance by using polyethylene adipate polyol and lactone ester polyol in combination at a predetermined ratio as polyols (see Patent Document 3). ).

  However, the squeegee for screen printing described in Patent Document 3 has a problem that since the polyurethane elastomer used is rich in crystallinity, the melting point is high, the moldability is poor, and the productivity is lowered.

  Further, a polyester polyol mixture composed of 10 to 90% by weight of a polyester polyol composed of ethylene glycol, diethylene glycol and succinic acid, and 90 to 10% by weight of a polyester polyol composed of neopentyl glycol, diethylene glycol and succinic acid, and a polyisocyanate and cured A squeegee for screen printing obtained by reacting with an agent is known. Such a screen printing squeegee is said to have good solvent resistance (see Patent Document 4).

  However, the squeegee for screen printing described in Patent Document 4 is a kind of “polyhydric alcohol having a side chain” that is generally known to reduce solvent resistance, although the resilience is relatively good. Since neopentyl glycol as an essential component is contained as an essential component, the solvent resistance to the organic solvent contained in the ink and paste used in screen printing is inferior.

  In the conventional polyurethane elastomer composition, since the polyester polyol used is mainly an ethylene glycol-adipic acid-based or ethylene glycol-succinic acid-based polyester polyol, the glass transition temperature (Tg) is relatively high, and the impact resilience is high. It had the disadvantage of high energy loss.

  As described above, the polyurethane elastomer composition for one-shot molding that excels in handling and moldability during production, and the elastomer properties (especially rebound resilience) are improved while maintaining the good solvent resistance of the polyurethane elastomer. Therefore, the development of a squeegee for screen printing that enables precise and precise printing in screen printing has been desired.

JP 59-129155 A JP 59-212269 A Japanese Patent Laid-Open No. 3-164254 JP-A-4-175325

  The present invention is directed to a polyurethane elastomer composition that is excellent in handling and moldability during production. Another object of the present invention is to provide a squeegee for screen printing in which the elastomer properties (especially rebound resilience) are improved while maintaining good solvent resistance of the polyurethane elastomer, and precise and precise printing is possible in screen printing.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor, as a result, a glycol component containing 1,3-propanediol and diethylene glycol or ethylene glycol as essential, and a polycarboxylic acid component containing succinic acid as essential A polyester polyol composition obtained by reacting a polyester polyol, a chain extender, and if necessary, a polyester polyol composition containing a urethanization catalyst, and a polyurethane elastomer composition containing a polyisocyanate, and having a specific range of use amount 1 , 3-propanediol and diethylene glycol or ethylene glycol are used together so that the polyester polyol is kept in a liquid state at room temperature, and a polyurethane elastomer composition excellent in handling property and moldability during production, and good polyurethane elastomer High solvent resistance While the elastomeric properties (especially impact resilience) is improved, it found that it is possible to obtain a screen printing squeegee capable precise and sophisticated printing in the screen printing, and have completed the present invention.

That is, the present invention uses 1,3-propanediol (a1) and diethylene glycol (a2) as essential components, and uses a polyhydric alcohol (a4) other than the optional components (a1) and (a2). In addition to the total amount of the above (a1) and (a2), a glycol component that is contained in an amount of 20 mol% or less, and a succinic acid (b) as an essential component and a poly component other than the above (b) that is an optional component When carboxylic acid is used, polyester polyol (A), chain extender (B) obtained by reacting with a polycarboxylic acid component contained at 30 mol% or less with respect to the total amount of the polycarboxylic acid component, necessary A polyester polyol composition containing a urethanization catalyst (C) according to the above and a polyurethane elastomer composition containing a polyisocyanate (D), the polyester polyol A polyurethane wherein the amount of 1,3-propanediol (a1) and diethylene glycol (a2) used in A) is in the range of (a1) / (a2) = 25/75 to 75/25 mol% The present invention relates to an elastomer composition.

Further, the present invention uses a polyhydric alcohol (a4) other than the above (a1) and (a3), which is an optional component, and contains 1,3-propanediol (a1) and ethylene glycol (a3) as essential components. In the case, other than the component (b) other than the component (b), which contains the glycol component contained at 20 mol% or less and the succinic acid (b) as an essential component and is an optional component with respect to the total amount of the components (a1) and (a3) When using a polycarboxylic acid, the polyester polyol (A) obtained by reacting the polycarboxylic acid component contained at 30 mol% or less with respect to the total amount of the polycarboxylic acid component, the chain extender (B), A polyester polyol composition containing a urethanization catalyst (C) as necessary and a polyurethane elastomer composition containing a polyisocyanate (D), the polyester polyol ( ) In which the amounts of 1,3-propanediol (a1) and ethylene glycol (a3) used are in the range of (a1) / (a3) = 75/25 to 90/10 mol% The present invention relates to an elastomer composition.

  The present invention also relates to a squeegee for screen printing, which is obtained by thermosetting the polyurethane elastomer composition.

  In the polyurethane elastomer composition of the present invention, since polyester polyol using 1,3-propanediol and diethylene glycol or ethylene glycol in a specific use amount is in a liquid state at room temperature, it is easy to handle and mold during production. Excellent. In addition, the squeegee for screen printing of the present invention has improved elastomer characteristics (particularly rebound resilience) while maintaining the good solvent resistance of the polyurethane elastomer, and enables precise and delicate printing in screen printing.

  The polyurethane elastomer composition of the present invention contains 1,3-propanediol (a1) (hereinafter also referred to as “1,3PDO”) and diethylene glycol (a2) (hereinafter also referred to as “DEG”) as essential components. And a polyester polyol (A) obtained by reacting succinic acid (b) (hereinafter also abbreviated as “SuA”) with a polycarboxylic acid component essential, a chain extender (B), and, if necessary, urethanization It comprises a polyester polyol composition containing a catalyst (C) and a polyisocyanate (D).

  In addition, the polyurethane elastomer composition of the present invention includes a glycol component that essentially includes 1,3PDO (a1) and ethylene glycol (a3) (hereinafter also abbreviated as “EG”), and a poly component that essentially includes SuA (b). A polyester polyol composition obtained by reacting a carboxylic acid component (A), a chain extender (B), a polyester polyol composition containing a urethanization catalyst (C) if necessary, and a polyisocyanate (D). It contains.

  In the present invention, in order to shift the Tg of the polyurethane elastomer (A) to a lower temperature side, the use amounts of 1,3PDO (a1) and DEG (a2) or EG (a3) in the polyester polyol (A) are changed. By limiting to a specific ratio range, a polyurethane elastomer composition having excellent characteristics suitable for screen printing squeegees can be obtained.

  The polyester polyol (A) used in the present invention comprises 1,3PDO (a1) and DEG (a2) as essential components as glycol components, or 1,3PDO (a1) and EG (a3). Must be used together. Of course, three parties of 1,3 PDO (a1), DEG (a2), and EG (a3) may be used.

In the case of using 1,3PDO (a1) alone without using DEG (a2) or EG (a3) as the polyol component, polyester polyol (A) having improved elastomer properties (particularly rebound resilience) is used. Since it becomes wax-like and handling property, productivity, and solvent resistance fall, the objective of this invention cannot be achieved.
In the case of using DEG (a2) alone without using 1,3PDO (a1) together, the polyester polyol (A) becomes liquid at room temperature, and handling properties and productivity are improved, but water absorption becomes too strong. Since the hydrolysis resistance of the polyester is lowered and the durability is lowered, it is not practical.
Further, in the case of using EG (a3) alone without using 1,3PDO (a1) in combination, the resulting polyester is too high in polarity and inferior in rebound resilience particularly in a low temperature range below room temperature. The goal cannot be achieved.
Further, when DEG (a2) and EG (a3) are used in combination without using 1,3PDO (a1) in combination, it is possible to make the polyester polyol liquid depending on the use ratio, but repulsion in elastomer properties. Since the elasticity is low, the object of the present invention cannot be achieved.

  Thus, in the case where DEG (a2) or EG (a3) is not used in combination with 1,3PDO (a1) as the glycol component constituting the polyester polyol (A), excellent elastomer characteristics are exhibited in any case. I can't do it.

  In the glycol component constituting the polyester polyol (A), when the 1,3PDO (a1) and DEG (a2) are used in combination, the amounts used of (a1) and (a2) are (a1) / ( a2) = 25/75 to 75/25 mol%, preferably 50/50 to 25/75 mol%. If the amount used of the above (a1) and (a2) is within such a range, the polarity of the polyester is moderately lowered and micro-Brownian motion is likely to occur even in a low temperature range of room temperature or lower, so that excellent rebound resilience can be expressed. When the amount of (a1) and (a2) used is outside the range, and 1,3PDO (a1) is less than 25 mol%, the solvent resistance tends to be inferior, and 1,3PDO (a1 ) Exceeding 75 mol% is not preferable because the polarity of the polyester is excessively increased and the resilience is lowered.

  In the glycol component constituting the polyester polyol (A), when the 1,3PDO (a1) and EG (a3) are used in combination, the amounts used of (a1) and (a3) are (a1) / (A3) = 75/25 to 90/10 mol%, preferably 75/25 to 85/15 mol%. If the amount of use of (a1) and (a3) is within such a range, the polarity of the polyester is moderately lowered and micro-Brownian motion is likely to occur even in a low temperature range below room temperature, so that excellent rebound resilience can be expressed. When the amount of use of (a1) and (a3) is outside this range, and 1,3PDO (a1) is less than 75 mol%, the polarity of the polyester is too high, and the resilience is reduced, When 1,3PDO (a1) exceeds 90 mol%, it becomes difficult for the polyol (A) to maintain a liquid state at room temperature, and it is not preferable because it solidifies.

  In addition, the polyester polyol (A) includes, as a glycol component, together with 1,3PDO (a1) and DEG (a2), which are essential components, or together with 1,3PDO (a1) and EG (a3), a polyhydric alcohol ( You may use a4) together.

  The polyhydric alcohol (a4) is not particularly limited as long as it does not adversely affect the reaction behavior and the performance and quality of the target product, and any conventionally known alcohol can be used. Polyhydric alcohols that do not have a side chain are preferred because polyhydric alcohols having side chains can provide better physical properties in terms of solvent resistance.

  Examples of the polyhydric alcohol having no side chain include 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Bifunctional components such as triethylene glycol, 1,4-cyclohexanedimethanol, bishydroxyethylbenzene (BHEB), trifunctional components such as trimethylolpropane (TMP), glycerin, hexanetriol, tetrafunctional components such as pentaerythritol, or And dimers such as trimethylolpropane (TMP) and pentaerythritol, and saccharides such as sorbitol and mannitol. Examples of the polyhydric alcohol having a side chain include 1,2-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, dipropylene glycol, 3,3. '-Dimethylol heptane and the like can be mentioned. Among these, 1,2-propanediol and 1,4-butanediol are more preferable because good resilience and solvent resistance can be obtained. These may be used alone or in combination of two or more.

  When using the polyhydric alcohol (a4), which is an optional component, together with the essential 1,3 PDO (a1) and DEG (a2), or the 1,3 PDO (a1) and EG (a3) as the glycol component The amount of (a4) used is preferably not more than 30 mol%, and not more than 20 mol%, based on the total amount of (a1) and (a2) or the total amount of (a1) and (a3). It is more preferable that

  The essential polycarboxylic acid component constituting the polyester polyol (A) is succinic acid (b) (hereinafter also abbreviated as “SuA”).

  All of the polycarboxylic acid components may be SuA (b), and a polycarboxylic acid other than SuA (b) may be used in combination with SuA (b) within a range that does not impair the object of the present invention. .

  When using polycarboxylic acid other than the optional component SuA (b) together with the essential component SuA (b) as the polycarboxylic acid component, the amount used is relative to the total amount of the polycarboxylic acid component. It is preferable not to exceed 50 mol%, more preferably 30 mol% or less.

  The polycarboxylic acid other than SuA (b) is not particularly limited, and examples thereof include aliphatic polycarboxylic acids such as oxalic acid, malonic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and dimer acid, cyclohexane Examples include alicyclic polycarboxylic acids such as pentanedicarboxylic acid and cyclohexanedicarboxylic acid, and aromatic polycarboxylic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. These may be used alone or in combination of two or more. May be.

  The polyester polyol (A) includes a glycol component that essentially contains 1,3PDO (a1) and DEG (a2), or a glycol component that essentially contains 1,3PDO (a1) and EG (a3), and SuA ( It can be obtained by reacting with a polycarboxylic acid component essentially containing b), and the synthesis method may be any known and commonly used method, and is not particularly limited.

  The number average molecular weight of the polyester polyol (A) (hereinafter also referred to as “Mn”, measured under the conditions described later by high performance liquid chromatography) is preferably in the range of 500 to 5000, more preferably 2000 to 3000. It is a range. If the Mn of the polyester polyol (A) is within such a range, the Japanese Industrial Standard (JIS) A hardness of the polyurethane can be set to a range suitable for various applications, and the temperature dependency is low, which is below normal temperature. A urethane elastomer having good impact resilience can be obtained even under low temperature conditions.

  The hydroxyl value of the polyester polyol (A) is preferably in the range of 10 to 100, more preferably in the range of 30 to 60. When the hydroxyl value of the polyester polyol (A) is within such a range, a urethane elastomer having good solvent resistance, elastomer physical properties (rebound resilience, etc.) and workability can be obtained.

  The acid value of the polyester polyol (A) is preferably 1.0 or less, more preferably 0.5 or less. When the acid value of the polyester polyol (A) is within such a range, the hydrolysis resistance of the polyester polyol and the reactivity with the isocyanate are good.

  The melt viscosity (measurement temperature 75 ° C.) of the polyester polyol (A) is preferably in the range of 10,000 mPa · s (hereinafter abbreviated as a unit), more preferably in the range of 5000. If the melt viscosity of the polyester polyol (A) is within such a range, the workability is good and the handling property (resin stirring, etc.) at the time of compounding is also excellent.

  In addition, for example, a polyol other than a polyester polyol such as a polyether polyol or a polycarbonate polyol can be used in combination with the polyester polyol (A) as long as the object of the present invention is not impaired.

  In the present invention, the chain extender (B) is essential. The chain extender (B) is not particularly limited, and any conventionally known one can be used. For example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1, 3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,6- Hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylol heptane, diethylene glycol, dipropylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, bishydroxyethylbenzene (BHEB), bishydroxy Bifunctional compounds such as methyl terephthalate (BHET), trimethylolpropane (TM ), Glycerine, tri-functional components such as hexanetriol, tetrafunctional component such as pentaerythritol or a dimer such as trimethylolpropane (TMP) or pentaerythritol, sorbitol, sugars such as mannitol and the like. Among these, since the impact resilience and solvent resistance can be improved by increasing the cohesion of the hard segment, ethylene glycol, 1,3-propanediol, 1,4-butanediol, trimethylolpropane (TMP) ) And bishydroxyethylbenzene (BHEB) are preferred, and ethylene glycol, 1,4-butanediol, trimethylolpropane, and bishydroxyethylbenzene (BHEB) are more preferred.

  What is necessary is just to set the usage-amount of the said chain extender (B) according to target hardness, and, thereby, the polyurethane elastomer composition excellent in rebound resilience and solvent resistance can be obtained. Usually, the usage-amount of a chain extender (B) becomes like this. Preferably it is the range of 1-25 mass% with respect to the usage-amount of a polyester polyol (A), More preferably, it is the range of 3-15 mass%.

  Moreover, in this invention, you may use a urethanization catalyst (C) as needed. The urethanization catalyst (C) is not particularly limited, and conventionally known catalysts can be used. For example, inorganic acids or organic acids; Li, Na, K, Rb, Ca, Mg, Sr, Zn, AL, Ti, Metal chlorides, oxides, hydroxides or acetic acid, oxalic acid, octylic acid, lauric acid or naphthenic acid such as V, Cr, Mn, Fc, Co, Ni, Cu, Zr, Pd, Sn, Sb, Pb Fatty acid salts such as sodium methylate, sodium ethylate, aluminum triisopropoxide, isopropyl titanate or n-butyl titanate, etc .; phenolates such as sodium phenolate; or Al, Ti, Zn, Sn , Zr, Pb and other metals, and other organometallic compounds.

  The amount of the urethanization catalyst (C) used is preferably in the range of 0.00001 to 5% by mass, more preferably 0, based on the total mass of raw materials used when the polyester polyol (A) is synthesized. The range is 0.001 to 2% by mass.

  Next, the polyisocyanate (D) used with the polyester polyol composition will be described below.

  The polyisocyanate (D) used in the present invention is not particularly limited, and conventionally known polyisocyanate (D) can be used. For example, diphenylmethane diisocyanate (abbreviation: MDI; its 4,4 ′ body, 2,4 ′ body) Or 2,2 ′ form, or a mixture thereof, crude MDI), carbodiimide-modified MDI (modified MDI), polymethylene polyphenyl polyisocyanate, carbodiimidized diphenylmethane polyisocyanate, tolylene diisocyanate (TDI; Or 2,6 or a mixture thereof), xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), aromatic diisocyanate such as tetramethylxylene diisocyanate, or isophorone diisocyanate (IPDI) Hydrogenated diphenyl Alicyclic diisocyanates such as tan diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), aliphatic diisocyanates such as hexamethylene diisocyanate (HDI), dimer acid diisocyanate, norbornene diisocyanate, etc. Among these, MDI, crude MDI, and modified MDI are preferable because they have moderate reactivity, excellent mechanical properties, and rebound resilience. These may be used alone or in combination of two or more.

  When the number of moles of isocyanate groups of the polyisocyanate (D) is represented by [NCO] and the number of moles of hydroxyl groups of the polyester polyol (A) and the chain extender (B) is represented by [OH], the molar ratio ( [NCO] / [OH]) is preferably in the range of 0.70 to 1.20, more preferably in the range of 0.90 to 1.10. When the [NCO] / [OH] molar ratio is within such a range, the polyurethane elastomer can have a high molecular weight, and excellent rebound resilience and durability can be obtained.

  Next, the polyurethane elastomer composition of the present invention will be described below.

  In general, the molding methods of polyurethane elastomer compositions are roughly classified into two methods: prepolymer molding and one-shot molding.

  In the prepolymer molding method, polyisocyanate (D) and polyester polyol (A) are reacted in advance (first step reaction) to synthesize a prepolymer, and then the prepolymer and chain extender (B) are combined. Is a two-stage reaction (second step reaction).

  In the prepolymer molding method, the viscosity of the isocyanate-terminated prepolymer obtained in the first step affects urethane molding. In particular, in the case of succinic polyester, since the viscosity is high, in the reaction with the chain extender (B) in the second step, a stirring failure is likely to occur. Therefore, it is necessary to perform molding while paying attention to how the resin is mixed.

  On the other hand, the one-shot molding method is a one-stage reaction in which a polyester polyol (A), a chain extender (B), and if necessary, a urethanization catalyst (C) and a polyisocyanate (D) are simultaneously mixed and stirred.

  The one-shot molding method has the advantage that the viscosity of the resin is relatively low, so that stirring is easy and molding failure due to poor mixing hardly occurs. Moreover, since the bonding arrangement of the polyester and the chain extender (B) becomes random, an improvement in resilience can be expected. On the other hand, since it is difficult for the resin to have a high molecular weight, it is necessary to sufficiently cure the resin after molding.

  The polyurethane elastomer composition of the present invention has no problem in production even if it is molded using either the prepolymer molding method or the one-shot molding method, but for the above reasons, it is molded using the one-shot molding method. Is preferred.

  The polyurethane elastomer composition of the present invention has a rebound elastic modulus measured according to a rebound resilience test specified in Japanese Industrial Standard JIS K-7312, preferably 35% or more, more preferably 40% or more. It becomes. When the rebound resilience of the cured product is 35% or more, the squeegee for screen printing obtained by thermosetting the polyurethane elastomer composition has excellent resilience, sufficiently stable printing pressure, and precise and precise printing. Is possible.

  The polyurethane elastomer composition of the present invention can contain conventionally known various additives as optional components within a range that does not impair the object of the present invention.

  Examples of such additives include, but are not limited to, plasticizers, antioxidants, defoaming agents, antifoaming agents, ultraviolet absorbers, reaction modifiers, reinforcing agents, fillers, colorants (dyes or pigments), Examples include mold release agents, stabilizers, light stabilizers, electrical insulation improvers, fungicides, metal salts of organic acids, waxes (amides, etc.), metal oxides, metal hydroxides, etc. Can do.

  The method for preparing the polyurethane elastomer composition is not particularly limited. For example, (Method 1) for one-shot molding comprising a polyester polyol (A), a chain extender (B), and a urethanization catalyst (C). A method in which the polyester polyol composition and the polyisocyanate (D) are stirred or mixed in a batch or divided and reacted, or (Method 2) contains the polyester polyol (A) and the chain extender (B). Examples thereof include a method in which the polyester polyol composition for one-shot molding, the urethanization catalyst (C) and the polyisocyanate (D) are stirred or mixed together and mixed to react. In that case, you may add and mix various additives etc. in arbitrary steps. Moreover, it can also prepare by carrying out a vacuum defoaming process as needed.

  The polyurethane elastomer composition of the present invention is excellent in handling and moldability during production because the polyester polyol used is kept in a liquid state at room temperature.

  Next, the screen printing squeegee of the present invention will be described.

  The squeegee for screen printing as used in the present invention is used for the purpose of extruding ink onto the surface to be printed by sliding on the screen under pressure, and is usually attached to the holder so as to have a predetermined angle on the surface to be printed. For example, it is an elastic plate made of a material such as polyurethane elastomer, silicon rubber, chloroprene rubber, butadiene rubber or the like. Therefore, the material, shape, hardness, and the like of this squeegee have a substantial influence on the characteristics of the squeegee and, in turn, have an important influence on the printing characteristics.

  The squeegee for screen printing of the present invention can be obtained by thermosetting the above-described polyurethane elastomer composition of the present invention, and has elastomer characteristics (particularly rebound resilience) while maintaining the excellent solvent resistance of the polyurethane elastomer. Improved and enables precise and fine printing in screen printing.

To produce the squeegee for screen printing of the present invention comprising a polyurethane elastomer composition using the polyester polyol (A), chain extender (B), urethanization catalyst (C) and polyisocyanate (D), for example, The following methods are mentioned.
That is, a polyester polyol (A) that has been dehydrated in advance, a chain extender (B), and a urethanization catalyst (C) are mixed to prepare a polyester polyol composition (polyol compound). The polyurethane elastomer composition was prepared by mixing and stirring at room temperature with polyisocyanate (D) at room temperature for 1 minute, poured into a mold adjusted to a temperature of 120 ° C., heated for 2 hours, and a sheet-like polyurethane elastomer molded article ( A molded sheet).
Furthermore, the squeegee for screen printing according to the present invention can be obtained by heating the molded sheet at 100 ° C. for 24 hours and performing secondary curing.

  In this case, the molar ratio of the polyisocyanate (D) to the polyester polyol composition (polyol compound) is such that the number of moles of isocyanate groups of the polyisocyanate (D) is [NCO] and that of the polyester polyol composition (polyol compound). When the number of moles of hydroxyl groups possessed is represented by [OH], the molar ratio ([NCO] / [OH]) is preferably in the range of 0.7 to 1.2, more preferably 0.9 to 1. .1 range.

  The squeegee for screen printing of the present invention has improved elastomer characteristics (particularly rebound resilience) while maintaining the good solvent resistance of polyurethane elastomers, and enables precise and precise printing in screen printing. It can be widely used for printing on printed wiring, clothing prints, ceramics, glass products, metals, plastic products, etc.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited only to these examples. Further, in the present invention, unless otherwise specified, “part” is “part by mass” and “%” is “mass%”.
The measurement method and evaluation method used in the present invention are as follows.

[Measuring method of melt viscosity of polyester polyol (A)]
The melt viscosity (mPa · s) of each polyester polyol (A) was measured under the following conditions.
Measuring instrument: BM viscometer (manufactured by Tokyo Keiki Co., Ltd.)
Measurement temperature: 75 ° C or 100 ° C
Rotor: No. 3
Number of revolutions: 6 RPM

[Measurement method of rebound resilience of thermosetting polyurethane molded product]
In accordance with the rebound resilience test specified in Japanese Industrial Standard JIS K-7312, a polyurethane elastomer composition was prepared and a thermosetting polyurethane molded article (cylindrical body) prepared as described later using the polyurethane elastomer composition was used as a test body. The elastic modulus was measured.
The measurement results of the resilience modulus were evaluated according to the following criteria.
○: 35% or more △: less than 35% 30% or more ×: less than 30%

[Method for measuring number average molecular weight (Mn) of polyester polyol (A)]
The number average molecular weights (Mn) of the polyester polyols (A1) to (A11) were measured by a calibration curve method using standard molecular weight polystyrene using high performance liquid chromatography (manufactured by Tosoh Corporation, HLC-8220).

[Measurement method of hydroxyl value / acid value / viscosity of polyester polyol (A)]
The hydroxyl value, acid value, and viscosity of the polyester polyol (A) were measured according to JIS K-1557 “Polyurethane Polyether Test Method”. The measurement results are shown in Table 2.

[Method of measuring hardness of polyurethane elastomer molded product]
The hardness of the polyurethane elastomer molded product was evaluated in accordance with JIS K-7311 “Method for testing physical properties of thermosetting polyurethane elastomer molded product”.

[Test method for solvent resistance]
(1) Test method for solvent resistance Each test piece (50 × 25 × 2 mm sheet) of a molded product of a thermosetting polyurethane elastomer composition is respectively a solvent [methyl ethyl ketone (MEK), isopropanol (IPA), butyl cellosolve (BCS). The mass change rate (%) after immersion for 22 hours at 25 ° C. is calculated according to the following formula to evaluate the solvent resistance.
Mass change rate (%) = W ₁ / W ₀ × 100
In the formula, W ₀ and W ₁ mean the following.
W ₀ : Mass of the test piece before the test W ₁ : Mass of the test piece after being immersed in each solvent at 25 ° C. for 22 hours In addition, the measurement result of the mass change rate was evaluated according to the criteria described in Table 1.

<Synthesis of Polyester Polyols (A1) to (A11)> (Synthesis Examples 1 to 11)
[Synthesis Example 1]
In a 5-liter four-necked flask, 1,3-propanediol (hereinafter abbreviated as “1,3PDO”) (a1) 458 parts as a glycol component, diethylene glycol (hereinafter abbreviated as “DEG”) (a2) 1917 parts, As a polycarboxylic acid component, succinic acid (hereinafter abbreviated as “SuA”) (b) 2625 parts and 0.05 part of tetrabutyl titanate (hereinafter abbreviated as “TBT”) as a catalyst were charged, and nitrogen was introduced from a nitrogen introduction tube. The reaction was carried out at 220 ° C. for 24 hours under an air stream.
After the reaction, the obtained polyester polyol (A1) was a pale yellow liquid at room temperature, and had an acid value of 0.45 and a hydroxyl value of 36.3.

[Synthesis Example 2]
A 5-liter four-necked flask was charged with 1,3 PDO (a1) 949 parts, DEG (a2) 1324 parts as a glycol component, 2727 parts SuA (b) as a polycarboxylic acid component, and 0.06 parts TBT as a catalyst, nitrogen The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the obtained polyester polyol (A2) was a pale yellow liquid at room temperature, and had an acid value of 0.50 and a hydroxyl value of 36.5.

[Synthesis Example 3]
A 5-liter four-necked flask was charged with 1,3 PDO (a1) 1477 parts as a glycol component, 687 parts DEG (a2), 2836 parts SuA (b) as a polycarboxylic acid component, and 0.06 parts TBT as a catalyst, and nitrogen The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the resulting polyester polyol (A3) was a pale yellow liquid at room temperature, having an acid value of 0.31 and a hydroxyl value of 36.7.

[Synthesis Example 4]
In a 5-liter four-necked flask, 1,66 PDO (a1) 1566 parts as a glycol component, 417 parts (a3) ethylene glycol (hereinafter abbreviated as “EG”), 3017 parts SuA (b) as a polycarboxylic acid component, and The catalyst was charged with 0.06 part of TBT, and reacted at 220 ° C. for 24 hours under a nitrogen stream from a nitrogen introduction tube.
After the reaction, the obtained polyester polyol (A4) was a pale yellow liquid at room temperature, having an acid value of 0.35 and a hydroxyl value of 37.1.

[Synthesis Example 5]
A 5-liter four-necked flask is charged with 1,856 PDO (a1) 1856 parts as a glycol component, 165 parts EG (a3), 2979 parts SuA (b) as a polycarboxylic acid component, and 0.06 part TBT as a catalyst, and nitrogen. The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the obtained polyester polyol (A5) was a pale yellow liquid at room temperature, and had an acid value of 0.28 and a hydroxyl value of 36.8.

[Synthesis Example 6]
A 5-liter four-necked flask is charged with 1856 parts of 1,3 PDO (a1), 165 parts of DEG (a2) as a glycol component, 2979 parts of SuA (b) as a polycarboxylic acid component, and 0.06 part of TBT as a catalyst, and nitrogen. The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the obtained polyester polyol (A6) was a pale yellow liquid at room temperature, and had an acid value of 0.41 and a hydroxyl value of 37.4.

[Synthesis Example 7]
A 5-liter four-necked flask is charged with 1700 parts of 1,3 PDO (a1), 418 parts of DEG (a2) as a glycol component, 2882 parts of SuA (b) as a polycarboxylic acid component, and 0.06 part of TBT as a catalyst, and nitrogen. The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the obtained polyester polyol (A7) was a pale yellow liquid at room temperature, and had an acid value of 0.38 and a hydroxyl value of 36.6.

[Synthesis Example 8]
A 5-liter four-necked flask was charged with 1,3 PDO (a1) 1065 parts as a glycol component, 852 parts EG (a3), SuA (b) 3083 parts as a polycarboxylic acid component, and 0.06 parts TBT as a catalyst, nitrogen The reaction was carried out at 220 ° C. for 24 hours under a nitrogen stream from the introduction tube.
After the reaction, the resulting polyester polyol (A8) was a pale yellow liquid at room temperature, having an acid value of 0.21 and a hydroxyl value of 38.3.

[Synthesis Example 9]
A 5-liter four-necked flask was charged with 1,46 PDO (a1) 2046 parts as a glycol component, 2954 parts SuA (b) as a polycarboxylic acid component, and 0.06 part TBT as a catalyst, and under a nitrogen stream from a nitrogen introduction tube, The reaction was carried out at 220 ° C. for 24 hours.
After the reaction, the obtained polyester polyol (A9) was a white solid at room temperature, and had an acid value of 0.39 and a hydroxyl value of 36.2.

[Synthesis Example 10]
A 5-liter four-necked flask is charged with 1375 parts of DEG (a2) as a glycol component, 788 parts of EG (a3), 2837 parts of SuA (b) as a polycarboxylic acid component, and 0.06 part of TBT as a catalyst, and a nitrogen introduction tube The reaction was further carried out at 220 ° C. for 24 hours under a nitrogen stream.
After the reaction, the resulting polyester polyol (A10) was a pale yellow liquid at room temperature, having an acid value of 0.16 and a hydroxyl value of 37.0.

[Synthesis Example 11]
A 5-liter four-necked flask was charged with 1777 parts of EG (a3) as a glycol component, 3223 parts of adipic acid (hereinafter abbreviated as “AA”) as a polycarboxylic acid component, and 0.06 part of TBT as a catalyst, and a nitrogen introduction tube The reaction was further carried out at 220 ° C. for 24 hours under a nitrogen stream.
After the reaction, the obtained polyester polyol (A11) was a white solid at room temperature, and had an acid value of 0.28 and a hydroxyl value of 37.2.

[Examples 1-3, 5, 6] and [Comparative Examples 1-6]
<Production of molded product by one-shot molding method 1>
According to the composition shown in Table 2, the polyester polyols (A1) to (A11) obtained in Synthesis Examples 1 to 11 are used, respectively, and the chain extender (B) is abbreviated as bishydroxyethylbenzene (hereinafter abbreviated as “BHEB”). ) Was heated and dissolved at 100 ° C. to prepare a polyester polyol composition (polyol compound).
Next, Coronate MX (trademark, manufactured by Nippon Polyurethane Co., Ltd., liquid MDI) as polyisocyanate (D), and Neostan U-830 (trademark, manufactured by Nitto Kasei Co., Ltd., dioctyltin didecanate) as urethanization catalyst (C) Were mixed and stirred to prepare a polyurethane elastomer composition, which was poured into a centrifugal molding machine set at a mold temperature of 120 ° C. and heated at 120 ° C. for 1 hour to prepare a 2 mm thick sheet-like urethane elastomer molded product. Further, it was secondarily cured at 110 ° C. for 16 hours to prepare a thermosetting polyurethane molded article for squeegee.
The evaluation results of Examples 1 to 3, 5, and 6 and Comparative Examples 1 to 6 are shown in Table 2.

[Examples 4 and 7]
<Creation of molded product by one-shot molding method 2>
According to the formulation shown in Table 2, polyester polyols (A2) and (A4) obtained in Synthesis Examples 2 and 4 were used respectively, and 1,4-butanediol (hereinafter referred to as “1,1,”) as the chain extender (B). 4BG ") / trimethylolpropane (hereinafter abbreviated as" TMP ") = 9/1 mass ratio mixture was mixed at 80 ° C. to prepare a polyester polyol composition (polyol compound).
Next, 4,4′-MDI as polyisocyanate (D) and Neostan U-830 (trademark, manufactured by Nitto Kasei Co., Ltd., dioctyltin didecanate) as a urethanization catalyst (C) are mixed and stirred to obtain a polyurethane elastomer composition. It was prepared, poured into a centrifugal molding machine set at a mold temperature of 120 ° C., and heated at 120 ° C. for 1 hour to prepare a 2 mm thick sheet-like urethane elastomer molded product. Further, it was secondarily cured at 110 ° C. for 16 hours to prepare a thermosetting polyurethane molded product for squeegee.
The evaluation results of Examples 4 and 7 are shown in Table 2.

Chain extender (B1): bishydroxyethylbenzene (BHEB)
Chain extender (B2): 1,4-butanediol / trimethylolpropane = 9/1 mass ratio Urethane catalyst (C): Neostan U-830 (manufactured by Nitto Kasei Corporation)
Polyisocyanate (D): Coronate MX (manufactured by Nippon Polyurethane Industry Co., Ltd.)

From Table 2, it can be seen that the polyester polyols (A1) to (A5) used in Examples 1 to 7 are liquid at room temperature and have excellent handling properties during production. On the other hand, since the polyester polyols (A9) and (A11) used in Comparative Examples 4 and 6 are solid at room temperature, complicated processes such as pulverization and heat-melting are indispensable, and handling properties during production are examples. It is significantly inferior to
Moreover, the polyurethane molded products obtained in Examples 1 to 7 are excellent in resilience and solvent resistance, and can provide a squeegee for screen printing that enables precise and precise printing in screen printing.
In Comparative Examples 1 and 2, since the amounts of 1,3PDO (a1) and DEG (a2) used are outside the range defined in the present invention, the polyurethane molded product obtained in Comparative Example 1 has excellent resilience. It was inferior in solvent resistance, and in Comparative Example 2, although it was excellent in solvent resistance, it was inferior in impact resilience.
In Comparative Example 3, the amount of 1,3PDO (a1) and EG (a3) used was outside the range specified in the present invention. Therefore, the polyurethane molded product obtained in Comparative Example 3 was repulsive although it had excellent solvent resistance. It was extremely inferior in elasticity.
Comparative Example 4 is an example in which only 1,3PDO (a1) is used as the glycol component constituting the polyester polyol (A9), and DEG (a2) or EG (a3) is not used in combination. Since the polyester polyol (A9) is a waxy white solid at room temperature, it was extremely inferior in handling property, productivity and moldability. In addition, the polyurethane molded product obtained in Comparative Example 4 has a rebound resilience and resistance to resistance as compared with Examples using a glycol component that essentially contains 1,3 PDO (a1) and DEG (a2) or EG (a3). It turns out that it is inferior to solvent property.
In Comparative Example 5, 1,3PDO (a1) is not used, and only DEG (a2) and EG (a3) are used together. However, the polyurethane molded product obtained in Comparative Example 5 is excellent in solvent resistance. The rebound resilience was extremely poor.
Comparative Example 6 is a case of polyester polyol (A11) using EG (a3) and adipic acid. Since the polyester polyol obtained from EG (a3) and adipic acid as a raw material is a white solid at room temperature, it is extremely inferior in handling property, productivity and moldability. The polyurethane molded product obtained in Comparative Example 6 was extremely inferior in resilience and solvent resistance.

  The polyurethane elastomer composition of the present invention is excellent in handling property and moldability during production because the polyester polyol is kept in a liquid state at room temperature. In addition, the squeegee for screen printing formed by thermosetting the polyurethane elastomer composition of the present invention has improved elastomer characteristics (particularly rebound resilience) while maintaining the good solvent resistance of the polyurethane elastomer, and is precise in screen printing. Therefore, it can be used for printing on posters, printed wiring, clothing prints, ceramics, glass products, metals, plastic products, and the like.

Claims (7)

When the polyhydric alcohol (a4) other than the above (a1) and (a2), which is an optional component, is essential and contains 1,3-propanediol (a1) and diethylene glycol (a2), ) And (a2) in the case of using a polycarboxylic acid other than the above-mentioned (b) which is an optional component and contains a glycol component contained at 20 mol% or less and succinic acid (b). Is a polyester polyol (A) obtained by reacting a polycarboxylic acid component contained at 30 mol% or less with respect to the total amount of the polycarboxylic acid component, a chain extender (B), and, if necessary, a urethanization catalyst. A polyurethane elastomer composition containing a polyester polyol composition containing (C) and a polyisocyanate (D), wherein 1 in the polyester polyol (A) A polyurethane elastomer composition, wherein the amount of 3-propanediol (a1) and diethylene glycol (a2) used is in the range of (a1) / (a2) = 25/75 to 75/25 (mol%) . In the case where polyhydric alcohol (a4) other than (a1) and (a3), which is an optional component, is essential and contains 1,3-propanediol (a1) and ethylene glycol (a3), When using a polycarboxylic acid other than (b) which is an optional component and contains a glycol component contained at 20 mol% or less and succinic acid (b) with respect to the total amount of a1) and (a3) The polyester polyol (A), the chain extender (B) obtained by reacting the polycarboxylic acid component contained in 30 mol% or less with respect to the total amount of the polycarboxylic acid component, and urethanization as necessary A polyester polyol composition comprising a catalyst (C) and a polyurethane elastomer composition comprising a polyisocyanate (D), wherein 1, 1 in the polyester polyol (A) -Polyurethane elastomer composition, wherein the amount of propanediol (a1) and ethylene glycol (a3) used is in the range of (a1) / (a3) = 75/25 to 90/10 (mol%) . The polyurethane elastomer composition according to claim 1 or 2, wherein the polyhydric alcohol (a4) is at least one selected from 1,2-propanediol and 1,4-butanediol. The polyurethane elastomer composition according to claim 1 or 2, wherein the polyester polyol (A) has a number average molecular weight in the range of 500 to 5,000. The polyurethane elastomer composition according to claim 1 or 2, wherein the chain extender (B) is at least one selected from 1,4-butanediol, trimethylolpropane, and bishydroxyethylbenzene. The polyurethane elastomer composition according to claim 1 or 2, which has a rebound resilience measured in accordance with a rebound resilience test specified in Japanese Industrial Standards JIS K-7312, having a cured product of 35% or more. A squeegee for screen printing, which is obtained by thermally curing the polyurethane elastomer composition according to any one of claims 1 to 6 .