JPH0378416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an elastic sheet-like material. More specifically, the present invention relates to a sheet material coated with an elastic body made of segmented polyurethane that does not contain air bubbles or pinholes, and a method for producing the elastic sheet material.

Segmented polyurethane is a general term for linear or relatively low crosslinking polyurethanes produced by the reaction of long-chain polyols, organic polyisocyanates, and low-molecular-weight diols. It is a block copolymer in which a rich molecular chain portion (soft segment) and a rigid and polar molecular chain portion (hard segment) formed by linking an organic polyisocyanate and a low-molecular diol are bonded alternately. Segmented polyurethane has excellent elasticity and mechanical strength due to its movable chain of soft segments and agglomerated structure of hard segments, making it particularly suitable for applications requiring wear resistance and durability. In addition, such segmented polyurethane can be cured without using harmful vulcanizing agents or peroxides, and has sufficient flexibility and elasticity without adding plasticizers like polyvinyl chloride. There is.

Therefore, it not only has wear resistance and durability, but also has excellent adaptability as a medical material and a material used in contact with food. Sheet materials made of segmented polyurethane are suitable for use with synthetic leather, conveyor belts, etc. A variety of uses have been found, including drive belts, backing and base materials for various mats, blood bag materials, flexible packaging materials, air bags, chipping prevention materials, food packaging materials, and food transportation materials.

Conventionally, such sheet materials made of segmented polyurethane have been produced by extrusion molding, inflation, calendering, etc. of thermoplastic polyurethane, or by coating with segmented polyurethane dope; The disadvantages are that the manufacturing cost is very high due to energy consumption and the large number of manufacturing process units.

Therefore, it would be of great industrial utility if a process could be found to produce coated sheet materials or sheet materials comprising segmented polyurethanes directly from long-chain polyols, organic polyisocyanates, and low molecular weight diols.

Generally, a three-component resin liquid consisting of a long chain polyol, an organic polyisocyanate and a low molecular weight diol, or a prepolymer obtained by reacting a long chain polyol with an excess amount of an organic polyisocyanate and a low molecular weight diol or A method for forming a segmented polyurethane into a coating sheet material or a sheet material from a two-component resin liquid consisting of a mixture of a low molecular weight diol and a long-chain polyol is to measure and mix the resin liquid, then apply it to a sheet-like base material and cure it. There is a method to do this, but there are disadvantages such as the appearance is poor due to the inclusion of voids and the formation of pinholes, and the inability to meet the functional characteristics of the intended use.
This method has hardly been industrialized.

We have intensively investigated methods for producing coated sheet materials or sheet materials made of segmented polyurethane directly from long-chain polyols, organic polyisocyanates, and low molecular weight diols, and
The present inventors have discovered a method for producing the sheet material, which is free from voids and pinholes and has excellent appearance and functional properties in terms of usage, leading to the present invention.

That is, the present invention has a thermal average molecular weight of 500 to 8000,
A three-component resin liquid consisting of a long chain polyol with a hydroxyl value of 20 to 170, an organic polyisocyanate, and a diol (low molecular weight diol) with a molecular weight of 50 to 350, or the above long chain polyol and an excess amount of the organic polyisocyanate. A two-component resin liquid consisting of the above diol of the prepolymer obtained by reacting or a mixture of the above long chain polyol and the above diol.
After measuring and mixing at a NCO group/OH group molar ratio of 0.8 to 1.2,
The curing process in the method of producing an elastic sheet material by flow-forming or coating on the surface of a sheet-like base material consists of the following two steps.

(a) Step of reaction and solidification in an atmosphere of 90°C or lower (b) Step of reaction and hardening in an atmosphere of 95 to 220°C In the present invention, a long-chain polyol with a thermal average molecular weight of 500 to 8000 and a hydroxyl value of 20 to 170 is used. These include polyether polyols, polyester polyols, polybutadiene polyols, polysiloxane polyols, etc., and polyether polyols or polyester polyols having 2- to 3-functionality at terminal hydroxyl groups are particularly preferred.

Typical polyether polyols include polymerized or copolymerized cyclic ethers such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran, or ethylene glycol, propylene glycol, 1,3-butanediol, glycerin, and trimethylolpropane. Those produced by polymerizing or copolymerizing one of the above cyclic ethers in the presence of an alkanediol such as Includes modified polyether polyols in which polymers are dispersed.

Polyester polyols include hydroxy-terminated polyesters in which one or more dicarboxylic acids and one or more aliphatic polyhydroxy compounds are prepared, and cyclic esters in which the aliphatic polyhydroxy compound is used as a reaction initiator to open the cyclic ester. These include hydroxyl-terminated polyesters obtained by ring polymerization, and hydroxyl-terminated polycarbonate esters obtained by transesterification of carbonate esters and aliphatic polyhydroxy compounds. Representative examples of dicarboxylic acids that can be used are succinic acid, glutanic acid, adipic acid, and benzenedicarboxylic acid. Examples of aliphatic polyhydroxy compounds include:
Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-
Butanediol, 1,4-butanediol, 1,
6-hexanediol, diethylene glycol,
Dipropylene glycol, 2,2-dimethyl-
Examples include 1,3-propanediol, glycerin, and trimethylolpropane. Cyclic esters include γ-butyrolactone, ε-caprolactone,
Examples include ζ-enantholactone, η-caprolactone, methyl-ε-caprolactone, and the like. Further, examples of carbonate esters include diethyl carbonate, dipropyl carbonate, ethylene carbonate, diphenyl cardonate, and the like.

Examples of organic polyisocyanates include aliphatic, cycloaliphatic, aromatic-substituted aliphatic, aromatic or heterocyclic polyisocyanates, such as hexamethylene-1,6-diisocyanate, 2,2,
4- or 2,2,6-trimethylhexamethylene-1,6-diisocyanate, 1-isocyanate-3,3,5-trimethyl-5-isocyanate methylcyclohexane, hexahydro-threlin-2,4- or 2,6- diisocyanate,
cis- or trans-cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,
4′-diisocyanate, ω,ω′-diisocyanate-trimethylcyclohexane, tolylene-2,
4- or -2,6-diisocyanate, diphenylmethane-2,4'- or 4,4'-diisocyanate, naphthylene-1,5-diisocyanate, bitolylene diisocyanate, m- or p-phenylene diisocyanate, xylylene-1 , 3- or -1,4-diisocyanates, polyphenylpolymethylene polyisocyanates of the type obtained by condensing aniline with formaldehyde and subsequent phosgenation, triphenylmethane-4,4′,4″-
Triisocyanate, tris(4-isocyanatophenyl)thiophosphate, N,N'-bis(ω-isocyanatepropyl)oxadiazinetrione, room temperature containing carbodiimide group or uretonimine group as described in West German Patent No. 1092007 liquid diphenylmethane diisocyanates, or urethane bonds, biuret bonds, urea bonds, allophanate bonds,
Examples include modified polyisocyanates containing a uretidione ring or an isocyanurate ring structure, and the above organic polyisocyanates can be used alone or as a mixture of two or more.

Among these, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate and all mixtures of these isomers, diphenylmethane-4,4'-disisocyanate, etc. due to ease of handling and commercial availability. Particularly preferred are cyanates and diphenylmethane 2,4'-disisocyanate and all mixtures of these isomers, liquefied diphenylmethane diisocyanates.

Diols with a molecular weight of 50 to 350 used in the present invention include aliphatic, alicyclic, aromatic-substituted aliphatic or heterocyclic diols, such as ethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propane Diol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, bis(β-hydroxyethoxy)benzene, p-xylylene diol, phenyldiethanolamine, methyldiethanolamine, 3,
9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, α,α-(isopropylidenedi-p-phenylene)bis-( ω-hydroxypropylene), etc. These can be used alone or as a mixture of two or more. Among these, because it is liquid at room temperature and easy to obtain commercially,
ethylene glycol, diethylene glycol,
1,4-butanediol and the like are particularly preferred.

The sheet-like base material used in the present invention is, for example,
Releaseable base materials, plastic films, metal thin plates or foils, cloth, paper, non-woven fabrics, sliced wood, etc. Among these, releaseable base materials include silicone-treated engineered paper, fluororesin coated cloth, polyolefin in-film, etc. Examples of plastic films include polyethylene terephthalate film, nylon film, polyvinylidene chloride film, polycarbonate film, polyimide film, and corona discharge treated polyolefin film. Metal thin plates include thin plates unwound from rolled steel coils, copper thin plates, aluminum foil, etc. Cloths include plain woven fabrics, twill woven fabrics, satin woven fabrics made of asbestos, glass, cotton, synthetic fibers, etc. Taffeta,
Tricotto etc. or pile-treated products thereof,
Alternatively, sheet materials such as leather and synthetic leather can also be used.

Further, the apparatus for implementing the present invention includes a blending apparatus, a coating apparatus, a curing apparatus, etc., and a conveying apparatus and a laminating apparatus are used as necessary.

The blending device is preferably a device that can measure each component resin liquid with a gear pump or a plunger pump, mix each component with a mixing head, and then discharge the mixed liquid.

As the coating device, a spread coating device such as a doctor knife, a spray device, or a device that coats the mixture by flowing it down from a slit can be used, and a spread coating method using a knife or blade is particularly suitable.

The curing device is preferably one that applies thermal energy to the sheet material efficiently by irradiating it with infrared rays or blowing hot air, and particularly preferably a device that heats the sheet material by continuously passing it through an oven.

In order to carry out the present invention, the resin liquid consisting of 2 to 3 components has an NCO group/OH group molar ratio of 0.8 to 1.2.
It is weighed and mixed so that it becomes . If the NCO group/OH group molar ratio is outside the above range, the physical properties and curing properties of the segmented polyurethane will deteriorate. NCO group/OH
More preferably, the group molar ratio is 0.95 to 1.05.

The resin that has flowed down or been applied to the sheet-like base material surface is
It can be reacted and solidified in an atmosphere below 90℃. The time required for solidification varies depending on the composition and ambient temperature, and becomes shorter when the segmented polyurethane has a high hard segment content or when the ambient temperature is high. Therefore, a particularly favorable atmosphere is
The temperature is 50-85℃. That is, a temperature of 90° C. or higher is undesirable because pinholes occur, and a temperature of 50° C. or lower is not very suitable in terms of production efficiency because the reaction solidification time becomes long.

The coating material that has reacted and solidified on the sheet substrate surface can be immediately reacted and hardened in an atmosphere of 95 to 220°C, but after cooling to room temperature in a reacted and solidified state, it can be cured in an atmosphere of 95 to 220°C. It can also be cured by reaction. In this case, the leaving time at room temperature is 2
Preferably within a day. If it exceeds 2 days, the physical properties of the segmented polyurethane after reaction curing become poor.

The curing process described above is carried out using a continuous coating device with two heating ovens, one at 90℃ or below and the other at 90℃ or below.
It can be carried out efficiently by keeping the temperature between 95 and 220°C.
In the case of a single heating oven, first set the temperature to 90°C or lower to allow the reaction to solidify, then heat it again to 95-220°C.
This can be carried out by heating and curing the temperature.

The reaction curing temperature is preferably low if the heating time is long, and vice versa. However, if the temperature does not reach 95°C, the physical properties of the segmented polyurethane will be poor, and if the temperature exceeds 220°C, the polyurethane will deteriorate, which is undesirable. A particularly preferred reaction curing temperature is 100 to 140
It is ℃.

In the present invention, fillers, reinforcing materials, catalysts, colorants, plasticizers, stabilizers, or other additives may be added to any of the long-chain polyols, organic polyisocyanates, and diols.

Next, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples.

Preparation of prepolymer Diphenylmethane-4 dissolved at 60℃ in a closed container equipped with a stirrer, thermometer, and nitrogen gas inlet tube.
After charging 508 parts by weight of 4'-diisocyanate and passing nitrogen gas above the liquid surface to fill the space in the closed container, stirring is started. Next, 50 parts by weight of polyoxypropylene triol (using glycerin as an initiator, molecular weight 2100) and 300 parts by weight polyoxypropylene glycol (molecular weight 700) were added.
Continue stirring for 4 hours while keeping the internal temperature at 80-90℃.
Isocyanate prepolymer A having an NCO content of 15.0% and a viscosity of 3800 cps/25°C was obtained.

Example 1 A coating device equipped with a knife-over roll coater and a 6 m long heated air blowing oven was used to
A 50 micron polyethylene terephthalate film was set, the gap for setting the coating thickness of the knife coater was set to 300 microns, and the oven temperature was set at 80°C. 280 parts by weight of isocyanate prepolymer A produced by preparing the prepolymer, poly(diethylene adipate) (hydroxyl value 56.0, acid value
0.1) 153.6 parts by weight, and 1,4-butanediol
38.4 parts by weight of the mixed liquid was heated at 25°C under a reduced pressure of 1 mmHg for 10 minutes.
After degassing for minutes, applying at room temperature, passing through an oven for 5 minutes, and cooling to 25°C, a sheet material with an opaque solid coating layer and almost no tack was obtained. . The oven temperature was then raised to 160° C., and the sheet material was passed through the oven for 6 minutes and cooled to room temperature, yielding a cured elastomer-coated sheet material with no pinholes or voids. When a Taber abrasion test was performed on this coated surface, the CS-17 abrasion wheel showed a wear amount of 5.2 mg per 1000 revolutions under a load of 1 kg.

Example 2 For the same coating equipment as in Example 1, a thickness of 0.6
A polyester plain woven fabric with a fabric weight of 250 g/m ² was set.

Isocyanate prepolymer A produced by preparing the prepolymer was placed in the first tank of Autospenser 201 type two-component compounding machine (manufactured by Automachine Kaihatsu Co., Ltd.).
In addition, the second tank was filled with 80 parts by weight of polyoxypropylene glycol (molecular weight 2000), 20 parts by weight of 1,4-butanediol, and 1 part by weight of Polycat SA-102 (tertiary amine catalyst, manufactured by Sun Abbott). and 1 mmHg under 1 mmHg while stirring at 25℃.
Degassed for an hour. The polymerization ratio of the first component (polyisocyanate component)/second component (polyol component) was maintained at 280/192, mixed and discharged, and first impregnated and coated. The impregnation coating conditions were: knife coater coating gap of 0 mm, coating speed of 2 m/min, and oven temperature of 130°C. With this coating, 105 g of polyurethane/
A plain woven polyester fabric impregnated with m ² was obtained.

The above-mentioned impregnated cloth was set in the coating machine, the coating gap of the knife coater was set to 300 microns, the oven temperature was set to 70°C, the liquid used for impregnation was applied in the same manner, and when the cloth was passed through the oven, it reacted and solidified. A coated sheet material was obtained. Add this material to another
When the mixture was left in an oven controlled at 120° C. for 3 minutes, a cured elastic-coated sheet material with a smooth surface without pinholes or voids was obtained. When a Taber abrasion test was performed on this coated surface, the CS-17 abrasion wheel showed a wear amount of 10.1 mg per 1000 rotations under a load of 1 kg.

Comparative Example 1 In Example 1, when the initial oven temperature was set to 100°C, pinholes and voids were observed, and the appearance was poor. Also, if the initial oven temperature is 80℃ and the next curing is not carried out, it will be a cheese-like solidified product, and if heated to 100℃ or higher,
It turned into mucus.

Comparative Example 2 When coating the impregnated cloth in Example 2, the initial oven temperature was 100°C, but voids and pinholes were generated and a smooth coated surface could not be obtained. Further, when the initial oven temperature was set to 90°C to cause reaction and solidification, no pinholes or voids were observed. This product was further held at 90℃ for 5 hours, and the coated surface was subjected to a Taber abrasion test.
The wear amount was 267 mg per 1000 revolutions, indicating that the physical properties were unfavorable.

Claims (1)

[Scope of Claims] 1. A three-component resin liquid consisting of a long chain polyol with a number average molecular weight of 500 to 8,000 and a hydroxyl value of 20 to 170, an organic polyisocyanate, and a diol with a molecular weight of 50 to 350, or the above long chain polyol and a prepolymer obtained by reacting this with an excess amount of organic polyisocyanate and a mixture of the above diol or the above long chain polyol and the above diol at an NCO/OH group molar ratio of 0.8 to 1.2. After measuring and mixing,
In a method of producing an elastic sheet material by flowing or coating onto the surface of a sheet-like substrate, the curing step includes (a) a step of reacting and solidifying in an atmosphere of 90°C or lower, and (b) a step of reacting and solidifying in an atmosphere of 95 to 220°C. A method for producing an elastic sheet material, comprising two steps: a step of reaction-curing.