JPS63303703A - Manufacture of flexible sheet or molding - Google Patents

Abstract

PURPOSE:To obtain a flexible sheet or molding with low density and high strength in a short time by injecting or jetting warm water or steam into the composition composed of the vegetable fine fiber and/or the vegetable powder and grain in a specified amount and NCO-terminated urethane prepolymer in a specified amount. CONSTITUTION:A composition contains 100 pts.wt. vegetable fiver and/or vegetable powder and grain and NCO-terminated urethane prepolymer of 1-100 pts.wt. Obtain this composition has been made into a sheet-shape or molding, warm water or steam is injected or jetted thereinto, or often warm water or steam has been injected into said composition, it is made into a sheet-shape or is molded. Further, the composition contains a surface active agent of 0.01-20 pts.wt. per 100 pts.wt. vegetable fiver. Consequently steam, etc. permeates the composition, a sheet shaped object or a formed ofject in short time, and the terminal urethane prepolymer is cured in a short time, whereby a sheet, a mat or a formed ofject may be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to converting waste vegetable fine fibers and/or vegetable powder (hereinafter referred to as vegetable fibers, etc.) into
This invention relates to a method for producing flexible sheets or molded articles by curing CO urethane prepolymers in a short period of time.

[Prior Art/Problems to be Solved by the Invention] A method for molding rice husks or wheat husks using a urethane binder is described in JP-A-55-86736. In this method, a moisture-curable urethane prepolymer is used as a binder to mold the rice husks and wheat husks, but the curing is performed simply by heating and applying pressure.
A method of curing using only moisture in the air and moisture in the adherend 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 there is insufficient moisture necessary 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. The affinity is poor and the effect is not sufficiently changed.

In these known methods, since the rate of reaction 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 problems]

The present invention was made in order to solve such problems, and a composition containing 100 parts (by weight, the same shall apply hereinafter) of vegetable fibers and the like and 1 to 100 parts of NCO-terminated urethane prepolymer is made into a sheet. The present invention relates to a method for producing a flexible sheet or a molded product, which comprises contacting the flexible sheet or molded product with hot water or steam, or forming or molding the flexible sheet or molded product into a sheet after contacting with hot water or steam.

〔Example〕

Specific examples of the vegetable fibers used in the present invention include wood flour, wood chips, cork flour, rice husks, rice husk charcoal, wheat husks, rice bran, seed lees, bean meal, buckwheat husks, and rice straw. However, it is not limited to these. These may be used alone or in combination of 21iJi or more.

The terminal NCO urethane prepolymer used in the present invention is
It 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, it is a prepolymer reacted at 2 to 5o, and the free M
The NCO content is 1 to 25%, preferably 2 to 15%.

If the equivalent ratio is less than 1.5, the viscosity of the urethane prepolymer becomes high, resulting in poor workability, and lO
If it exceeds O, the cured product tends to become brittle.

The prepolymer used in the present invention is a terminal 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, 1.8-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, 1.2.6-hexanediol, and pentyl glycol. Low molecular weight polyols such as erythritol, α-methyl glycoside, sorbitol, sucrose, and castor oil, and low molecular weight amines such as these polyols and ethylenediamine, diethylenetriamine, piperazine, methylamine, n-butylamine, aniline, and xylylene diamine. polyoxyalkylene polyols with alkylene oxides added to them; polyoxyalkylene monools with alkylene oxides added to monoalcohols such as methanol, ethanol, butanol, hexanol, octatool, phenol, cresol, and alkylphenols; ethylene glycol, 1
．． Polyester polyols, polycaprolactone polyols, dimer acid polyols obtained by the condensation reaction of polyols such as 4-butanediol, l, 6-hexanediol, and dibasic acids such as adipic acid and phthalic acid;
Examples include polycarbonate polyol, polybutadiene polyol, acrylic polyol, ethylene-vinyl acetate copolymer hydrolyzate, chlorobrene polyol, and the like. These may be used alone or in combination of two or more.

Examples of the organic polyisocyanate compound include tolylene diisocyanate (TDI), crude tolylene diisocyanate < in-house TD+), diphenylmethane diisocyanate (MDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), and polymethylene polyphenylisocyanate (crude MDI). ), hexamethylene diisocyanate, xylene diisocyanate (XD
I), 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 28 or more.

In the present invention, 100 parts of vegetable fiber, 1 to 100 parts of a terminal NCO urethane prepolymer, and preferably 0.01 to 20 parts of a surfactant, if necessary, are used.
After the composition is formed into a sheet or shaped, it is brought into contact with hot water or steam, preferably injected or sprayed, and cured, or the composition is heated with hot water or steam. After being brought into contact with each other, it is formed into a sheet or molded.

Specific examples of surfactants that may be used include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, silicone surfactants, and fluorine surfactants. can give.

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 amines, such as aliphatic alcohols such as ethylene lauryl ether polyoxyethylene ether, polyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan monolaurate. Examples of amphoteric surfactants include silicone surfactants such as betaine-type amphoteric surfactants, etc. Examples include dimethylsiloxane containing a polyoxyalkylene group, dimethylsiloxane containing a quaternary ammonium salt, etc. 1. Examples of fluorinated surfactants include alkylene oxide adducts to fluorine-containing alcohols.

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, so that the urethane foam is Helps to even out the cells. It also helps improve the wettability of urethane prepolymers such as vegetable fibers and moisture.

Other additives that may be used as necessary include:
Examples 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 O-urethane prepolymer.

There is no particular limitation on the order of blending each raw material, and the terminal NCO urethane prepolymer and the surfactant used if necessary may be mixed in advance and vegetable fiber etc. may be blended. may be mixed at the same time.

If the proportion of the terminal urethane prepolymer used is less than 1 part per 100 parts of vegetable fiber, the adhesive strength will be weak (
If the amount exceeds 100 parts, the characteristics of the vegetable ingredients will be lost.

Furthermore, if the ratio of surfactant used is less than 0.01 part per 100 parts of vegetable fiber, etc., the cells of the urethane foam will become uneven, and the wetting of the vegetable fiber, etc. with the urethane prepolymer and water will be poor. It may happen, 20
If the water exceeds 100%, the water resistance deteriorates (or the surface tends 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, or wooden mold can be used.In the method of the present invention, excessive hot water or steam is used, but since these act as a mold release agent, the mold hard to adhere to.

The temperature of the hot water that is brought into contact with the thus formed sheet-like article or molded article to cure it, or the temperature of the hot water that is brought into contact with the composition before forming it into a sheet-like article or molded article, is as follows: A temperature as high as possible, above 50°C, is preferred. A specific curing method is to spray, pour, or press-fit the composition onto the surface of the composition, sheet-like object, or molded object by a method such as injection or spraying, and then
It is preferable to cure under heating conditions of room temperature to 100°C.

Steam may be brought into contact instead of hot water, and the pressure in this case is preferably 0.3 to 15 kg/cgfG.

The present invention makes effective use of waste materials such as wood flour and rice husks, and uses a moisture-curable terminal NCO urethane prepolymer as a binder to create a composition containing a large amount of highly hydrophilic vegetable fibers. Because hot water or steam is injected or sprayed into contact with the composition, the steam penetrates into the composition, sheet-like object, or molded object in a short period of time, hardens the terminal urethane prepolymer in a short period of time, and forms a sheet, mat, or molded object. can manufacture products.

In addition, the sheet, mat, or molded product obtained by the method of the present invention has a urethane binder that 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 A mixture of glycerin propylene oxide adduct (average molecular weight approximately 5000)/polyoxypropylene diol (average molecular weight approximately 3000) -50150 and T
30 parts of a diluted solution consisting of 90% NCO-terminated urethane prepolymer (free NCO content 3.5%) obtained from DI-80 and 10% methyl ethyl ketone, wood flour (discharged from a factory that saws logs of cedar and cypress) Moisture content: 5
．． 9%, 20% that passed through 60 mesh, 12% that passed through 60-4B mesh, 68% that did not pass through 48% mesh)
After premixing a composition consisting of 50 parts of rice husk smoked charcoal (average particle size of 1.5 dragons) and 5 parts of Neugen ET137 (a nonionic surfactant manufactured by Daiichi Kogyo Seiyaku ■), the height Variable aluminum mold (vertical IQaa, horizontal 7CI+, height 5
011), water vapor with a vapor pressure of 5 kg/c- was injected and held for 5 minutes.

When the obtained molded body is dried at 80°C for 5 hours, the density becomes 0.
．． The molded product weighing 29g/cs3 was replaced. The compressive strength according to autograph is 5.3 kg/cj, and the tensile strength of the sheet obtained by slicing into 3.5-inch thick sheets (JIS K 6
301) was 3.4 kg/c-.

Example 2 Polyethylene glycol (average molecular weight approximately 2000) 80
and 20 parts of glycerin propylene oxide adduct (average molecular weight approximately 5000) and liquid MDI 1
Prepolymer obtained from 13 parts (free NCO content 1
Dilute 100 parts of 3.5%) with 15 parts of acetone, mix with 1000 parts of rice husk smoked charcoal, and place in a mold made of 100 mesh wire mesh (50 cm long, 18 cm wide, 5 cm high) according to the volume ratio. After press-fitting to a temperature of 415°C, it was immersed in 90°C warm water for 3 minutes.

The molded product taken out was left to dry at 20°C for one week, and the density was 0.23 kg/cII" and the compressive strength was 4.
．． The tensile strength of the sheet obtained by slicing into 7 kg/cj and 3.5 cm thick sheets was 1.9 kg/cd.

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.

The compressive strength was measured by removing a core with a diameter of 5 mm from the molded product, compressing it from both sides using an autograph, and measuring the strength at which the core would break.

[Margin below]

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.

〔Effect of the invention〕

According to the method of the present invention, a low-density, high-strength flexible sheet or molded product can be changed in a single hour, and continuous production is possible.

Claims (1)

[Claims] 1. Vegetable fine fibers and/or vegetable powder 100
parts by weight and 1 to 100 parts by weight of NCO-terminated urethane prepolymer is formed into a sheet or formed and then contacted with hot water or steam, or contacted with hot water or steam and then formed into a sheet. or a method for producing a flexible sheet or molded product. 2 The composition further contains 0.0 parts by weight of a surfactant per 100 parts by weight of the vegetable fine fibers and/or vegetable powder.
The method according to claim 1, comprising 1 to 20 parts by weight. 3. The method according to claim 1, wherein the contact between the composition and hot water or steam is carried out by injection or injection of hot water or steam.