JPH0521041B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention enables waste vegetable fine fibers and/or vegetable powder particles (hereinafter referred to as vegetable fibers, etc.) to be cured with an NCO-terminated urethane prepolymer in a short time. The present invention relates to a method of manufacturing a flexible sheet or molded article. [Prior Art/Problems to be Solved by the Invention] A method of molding rice husk or wheat husk using a urethane binder is described in JP-A-55-86736. In this method, a moisture-curing urethane prepolymer is used as a binder to mold rice husks and wheat husks, but the curing is performed simply by heating and pressurizing (because moisture in the air and A method of curing using only the moisture in the adhered body is used), and a method of specifically supplying moisture is not adopted. Therefore, when a urethane prepolymer with a high free NCO content is used as a binder, there is a drawback that moisture is insufficient for curing and molding takes time. On the other hand, JP-A-59-106932 describes a method of compacting hydrophobic adherends such as rubber chips and urethane chips in the presence of water at a construction site. It has poor affinity and does not produce sufficient effects. In these known methods, since the reaction rate between NCO groups and water is slow, there is a problem in that productivity is low even if the production process is integrated into a line to continuously produce products. [Means for solving the problem] The present invention was made to solve the problem, and contains 100 parts (parts by weight,
Terminal NCO urethane prepolymer 1 with a free NCO content of 2 to 15%, which is obtained by reacting a polyol or a monool with an organic isocyanate (the same applies below)
-100 parts of the composition is made into a sheet or shaped and then brought into contact with hot water or steam, or after being brought into contact with hot water or steam and made into a sheet or shaped. related to the manufacturing method of adhesive sheets or molded products. [Example] Specific examples of the vegetable fibers used in the present invention include wood flour, wood chips, cork powder, rice husks, rice husks, smoked charcoal, wheat husks, rice bran, seed lees, bean meal, buckwheat husks, and rice straw. Examples include, but are not limited to, these. These may be used alone or in combination of two or more. The terminal NCO urethane prepolymer used in the present invention is a reaction product of a polyol or monool and an organic polyisocyanate compound, and the equivalent ratio of the isocyanate group to the hydroxyl group of the polyol or monool is 1.5 to 100, preferably 2 to 1. 50% reacted prepolymer with a free NCO content of 2 to 15
%belongs to. If the equivalent ratio is less than 1.5, the viscosity of the urethane prepolymer becomes high, resulting in poor workability, and if it exceeds 100, the cured product tends to become brittle. Note that the prepolymer used in the present invention has terminal
It is an NCO urethane prepolymer, and by using such a prepolymer, it can be cured by moisture and bonded to vegetable fibers and the like. Specific examples of the polyols and monools include ethylene glycol, propylene glycol, hydroquinone, bisphenol A,
1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane,
Low molecular weight polyols such as 1,2,6-hexanetriol, pentaerythritol, α-methyl glycoside, sorbitol, seurose, and striped oil, these polyols, ethylenediamine, diethylenetriamine, piperazine, methylamine, n-butylamine, Polyoxyalkylene polyols are made by adding alkylene oxides to low molecular weight amines such as aniline and xylylene diamine, and alkylene oxides are added to monoalcohols such as methanol, ethanol, butanol, hexanol, octanol, buenol, cresol, and alkylphenols. Added polyoxyalkylene monool, further ethylene glycol, 1,4-butanediol, 1,
Polyester polyols, polycaprolactone polyols, dimer acid polyols, polycarbonate polyols, polybutadiene polyols, acrylic polyols, and ethylene-vinyl acetate polyols obtained by the condensation reaction of polyols such as 6-hexanediol with dibasic acids such as adipic acid and phthalic acid. Examples include polymer hydrolysates and chloroprene polyols. These may be used alone or in combination of two or more. As the organic polyisocyanate compound,
For example, tolylene diisocyanate (TDI), crude tolylene diisocyanate (crude TDI), diphenylmethane diisocyanate (MDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI),
Polymethylene polyphenyl isocyanate (crude
MDI), hexamethylene diisocyanate, xylene diisocyanate (XDI), hydrogenated xylene diisocyanate (hydrogenated XDI), naphthalene diisocyanate, isophorone diisocyanate, etc., but are not limited to these. These may be used alone or in combination of two or more. In the present invention, 100 parts of vegetable fiber etc. and 1 to 100 parts of the above-mentioned terminal NCO urethane prepolymer are used.
After the composition is made into a sheet or formed, it is contacted with hot water or steam, preferably with The composition may be injected or sprayed and cured, or after contacting the composition with hot water or steam, it may be formed into a sheet or molded. Specific examples of surfactants that may be used if necessary include anionic surfactants, cationic surfactants,
Examples include nonionic surfactants, amphoteric surfactants, silicone surfactants, and fluorine surfactants. Examples of the anionic surfactants include higher alcohol sulfate salts such as sodium dodecylbenzenesulfonate, sulfated castor oil, sodium lauryl sulfate, and sodium cetyl sulfate; examples of nonionic surfactants include polyoxy Examples of cationic surfactants include higher aliphatic surfactants, such as aliphatic alcohol polyoxyethylene ether, such as ethylene lauryl ether, polyethylene sorbitan fatty acid ester, such as polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan monolaurate. Examples of amphoteric surfactants include amine salts, higher alkyl quaternary ammonium salts, alkylbenzyl quaternary ammonium salts, and quaternary ammonium salts having a nitrogen ring; silicone surfactants such as betaine type amphoteric surfactants; Examples of the surfactant include dimethylsiloxane containing a polyoxyalkylene group and dimethylsiloxane containing a quaternary ammonium salt. Examples of the fluorine-based surfactant include an adduct of alkylene oxide to a fluorine-containing alcohol. The surfactant used if necessary in the method of the present invention causes the reaction between the terminal NCO urethane prepolymer and water to occur uniformly, accelerates the reaction, and also acts as a foaming agent. Helps to even out the cells. It also helps improve the leakage of urethane prepolymers such as vegetable fibers and moisture. Other additives that may be used as necessary include solvents, plasticizers, colorants, inorganic fillers, catalysts, flame retardants, fungicides, insecticides, and discoloration inhibitors. It is preferable to use it in an amount not exceeding 100 parts per 100 parts of NCO urethane prepolymer. There is no particular limitation on the order of blending each raw material, and the terminal NCO urethane prepolymer and a surfactant to be used if necessary may be mixed in advance and vegetable fiber etc. may be blended. These may be mixed at the same time. When the proportion of the terminal urethane prepolymer used is less than 1 part per 100 parts of vegetable fiber, etc.
The adhesive strength becomes weak, and if the amount exceeds 100 parts, the characteristics of the vegetable ingredients will be lost. Furthermore, the proportion of surfactants used is higher than that of vegetable fibers.
If the amount is less than 0.01 part per 100 parts, the cells of the urethane foam may become uneven, causing poor leakage between vegetable fibers, urethane prepolymer, and water, and if it exceeds 20 parts, the water resistance will deteriorate. This tends to cause the surface to become sticky. There are no particular limitations on the method of forming or molding the composition into a sheet before or after contacting it with hot water or steam, such as putting it into a normal mold or continuously and uniformly arranging it on a belt conveyor. This can be done in the following way. As a mold that can be used during molding, any mold such as a metal mold, resin mold, wooden mold, etc. can be used, and the method of the present invention uses excessive hot water or steam,
These act as mold release agents, making them difficult to adhere to the mold. The temperature of the hot water with which the sheet-like product thus formed is brought into contact to cure the molded product, or the temperature of the hot water with which the composition is brought into contact before being formed into a sheet-like product or molded product, is as follows: A temperature as high as possible, above 50°C, is preferred.
The specific curing method involves spraying, pouring, or press-fitting the composition onto the surface of the composition, sheet-like object, or molded object using a method such as injection or spraying, and then curing at room temperature to 100°C. It is preferable to let Steam may be used instead of hot water, and the pressure in this case is 0.3 to 15 kg/cm ²
G is preferred. The present invention makes effective use of waste materials such as wood flour and rice husks, and uses moisture-curable specific terminals.
NCO urethane prepolymer is used as a binder, and hot water or steam is injected or sprayed into contact with a composition containing a large amount of highly hydrophilic vegetable fibers, etc., so water vapor can be quickly removed from the composition or sheet-like material. It penetrates into molded products and hardens the terminal urethane prepolymer in a short time, making it possible to produce sheets, mats, or molded products. In addition, in the sheets, mats, or molded products obtained by the method of the present invention, the urethane binder is not an elastomer but a foam due to carbon dioxide gas generated by the reaction between NCO groups and moisture and the action of excess moisture during drying. This makes the product very soft and flexible. This is thought to be because the hardening of the urethane surface is accelerated by contact with hot water or steam, and carbon dioxide gas generated inside tends to remain inside the binder, resulting in a foam with a high expansion ratio. Furthermore, in the present invention, since the reaction is accelerated with hot water or steam, almost no unreacted NCO remains, and there is no adverse effect on the human body of the user. Next, the manufacturing method of the present invention will be explained based on Examples and Comparative Examples. Example 1 Terminal NCO urethane prepolymer (free NCO 30 parts of a diluted solution consisting of 90% (3.5% content) and 10% methyl ethyl ketone, wood flour (ground flour discharged from a factory that saws cedar and cypress logs, moisture content 5.9%, particle size passing 60 mesh 20
%, 60-48 mesh 12%, 48% mesh not passed 68
%) 50 parts, rice husk smoked charcoal (average particle size approximately 1.5 mm)
After premixing a composition consisting of 50 parts of Neugen ET137 and 5 parts of Neugen ET137 (a nonionic surfactant manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a height-variable aluminum mold (height: 10 cm,
7 cm in width and 5 cm in height), water vapor with a vapor pressure of 5 Kg/cm ² was injected, and the mixture was held for 5 minutes. When the obtained molded body is dried at 80℃ for 5 hours,
A molded article with a density of 0.29 g/cm ³ was obtained. The compressive strength by autograph is 5.3Kg/cm ² , and the tensile strength of the sheet sliced into 3.5mm thickness (JIS K
6301) was 3.4Kg/ ^cm2 . Example 2 Polyethylene glycol (average molecular weight approximately 2000)
A mixture of 80 parts and 20 parts of propylene oxide adduct of glycerin (average molecular weight approximately 5000) and liquid MDI
100 parts of the prepolymer (free NCO content 13.5%) obtained from 113 parts was diluted with 15 parts of acetone and mixed with 1000 parts of rice husk charcoal, and a mold made of 100 mesh wire mesh (height 50 cm, width 16 cm) was prepared. , height 5 cm) and press-fitted to a volume ratio of 4/5, and then immersed in warm water at 90°C for 3 minutes. The molded product was left to dry at 20°C for one week, and its density was 0.23g/cm ³ and its compressive strength was 4.7kg/cm 3 .
The tensile strength of the sheet sliced into cm ² and 3.5 mm thick sheets was 1.9 Kg/cm ² . Examples 3 to 6 and Comparative Examples 1 to 4 Various prepolymers shown in Table 1 were produced in the same manner as in Example 2, and the compositions shown in Table 1 were prepared and cured, resulting in molded products. The physical properties were measured. The results are shown in Table 1. In addition, the compressive strength is 5 cm in diameter from the molded product obtained.
The core was removed, and the core was compressed from both sides using an autograph to measure the strength at which the core would break.

[Table] From the results in Table 1, it can be seen that in the case of the comparative example, the demolding time was extremely long and the compressive strength was weak. [Effects of the Invention] According to the method of the present invention, a low-density, high-strength flexible sheet or molded product can be obtained in a single time, and continuous production is possible.

Claims (1)

[Claims] 1. Vegetable fine fibers and/or vegetable powder
NCO urethane prepolymer 1 with a free NCO content of 2 to 15%, obtained by reacting 100 parts by weight with a polyol or monool and an organic isocyanate.
~100 parts by weight of the composition is made into a sheet or shaped and then brought into contact with hot water or steam, or alternatively, the composition is made into a sheet or shaped after being brought into contact with hot water or steam. Manufacturing method for flexible sheets or molded products. 2. The method according to claim 1, wherein the composition further contains 0.01 to 20 parts by weight of a surfactant per 100 parts by weight of vegetable fine fibers and/or vegetable powder. 3. Contacting the composition with hot water or steam,
The manufacturing method according to claim 1, which is carried out by injection or injection of hot water or steam.