JPS5942697B2 - Method for manufacturing long polyurethane foam sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a modified long polyurethane foam sheet.

In general, polyurethane foam sheets have excellent elasticity and texture, and are therefore used in large quantities for clothing, interior decoration, industrial materials such as adhesive tape materials, and audio-related materials such as speaker edge materials.

By the way, conventionally, polyurethane foam sheets are made of large polyurethane foam blocks of arbitrary thickness (usually 3 to 20 mm).
It is obtained by slicing it into pieces (wrnl).

However, such a method has the disadvantage that it is not possible to consistently and continuously manufacture a foamed sheet, the manufacturing process becomes complicated, and the manufacturing cost of the sheet increases. Furthermore, the resulting foamed sheet had the drawback of insufficient hardness and poor shape retention. For this reason, the present applicant has developed a method for producing a long urethane foam sheet, in which a urethane stock solution is first coated on a continuously running base material using a prepolymer method, and then introduced into a steam tank and foamed. Special application 1977-8
No. 3869, JP-A No. 53-8664), etc.
However, although a long urethane foam sheet of a predetermined thickness can be obtained very efficiently using this method, the sheet is not always fully satisfactory in terms of hardness, that is, shape retention. Therefore, as a result of further intensive research based on the above-mentioned method, the present invention has developed a method in which a polyhydroxyl compound and an organic isocyanate are used as the prepolymer stock solution when applying the urethane prepolymer stock solution onto a continuously running base material and foaming it. By mixing and reacting a modifier consisting of one or more of propylene glycol, saccharides, molasses, and blackstrap molasses, the hardness can be modified and the shape retention can be significantly improved. It has been found that a long polyurethane foam sheet with an improved predetermined thickness can be obtained extremely efficiently.

The present invention will be explained in detail below.

First, a polyhydroxyl compound and an organic isocyanate are mixed and reacted with a modifier consisting of one or more of propylene glycol, saccharides, molasses, and blackstrap molasses, and if necessary, a catalyst and other foam stabilizers ( For example, surfactants, silicone oil, etc.), fillers, water permeable agents such as pulp, etc. are added to prepare a urethane prepolymer stock solution.

Next, a base material (for example, an endless vest with mold releasability) that continuously runs the urethane prepolymer stock solution
After applying it to one end with a discharge doctor knife or using a roll coating method, the urethane prepolymer stock solution of the desired thickness is foamed by introducing it into a steam tank where water vapor has been sprayed, and forming the desired thickness. Depending on the conditions, the polyurethane foam sheet is passed through a dryer and cured to form a long polyurethane foam sheet. (Polyhydroxyl compounds used in the present invention include, for example, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, hexylene glycol (bifunctional), glycerin, trimethylolethane, trimethylolpropane, 1,2,6- Hexatriol (3' functional or pentaerythritol, α-methyl glycoside, ethylenediamine (4 functional)
etc., by addition polymerization of ethylene oxide, 2-butylene oxide, propylene oxide, etc. Examples of the organic isocyanate which is reacted with the polyhydroxyl compound used in the present invention to form the prepolymer include tolylene diisocyanate, naphthalene diisocyanate, diphenylmethane diisocyanate, and the like. The prepolymer in the present invention has free N
It is desirable to use one adjusted to contain 6 to 20% CO. The reason for this is that free NCs in the prepolymer
If the amount of O is less than 6%, the viscosity will increase and workability will be hindered, while if the amount of cut exceeds 20%, urea bonds will increase and the strength of the obtained foam sheet will decrease. . Examples of the catalyst used in the present invention include tin-based catalysts such as stannous octoate, stannous olefinate, and stannous dioctoate, or amine-based catalysts such as ethylenediamine, trimethylamine, ethylmolleforin, and triethanolamine. can be mentioned.

The modifier used in the present invention consists of one or more of propylene glycol, monovalent or polyvalent sugars, molasses, and blackstrap molasses. In particular, propylene glycol or blackstrap molasses improves hardness. It is effective only when the effect is high.

Furthermore, if the waste molasses contains water, it is preferable to dehydrate it.
In the present invention, the modifier is preferably added in an amount of 5 to 150 parts by weight, preferably 10 to 60 parts by weight, per 100 parts by weight of the polyhydroxyl compound in the urethane prepolymer stock solution.

The reason for this is that if the amount of the modifier added is less than 5 parts by weight, the desired hardness modification effect cannot be achieved sufficiently, while if the amount added exceeds 150 parts by weight, This is because the properties such as elasticity of the obtained foam sheet itself are impaired.

In the method of the present invention, if necessary, the urethane prepolymer stock solution may be introduced into a steam tank and foamed, and then compressed to an arbitrary thickness using rolls or the like.

In this way, a long polyurethane foam sheet whose specific gravity is arbitrarily increased can be easily obtained. Next, examples of the present invention will be described.

Example 1 37 parts by weight of tolylene diisocyanate and 15 parts by weight of propylene glycol were mixed with 100 parts by weight of a trivalent polyether polyol (manufactured by Sanyo Kasei Co., Ltd., product name: GP3OOO) with an OH value of 56, and the mixture was heated at 90°C for 2 hours. A polyether urethane prepolymer composition having a free NCO content of 10% was prepared by a stirring reaction for a period of time, and then 100 parts by weight of this composition was mixed with 0.0% of a tin-based catalyst (trade name: U-28, manufactured by Nitto Kasei Co., Ltd.). A urethane prepolymer stock solution was prepared by adding 5 parts by weight of N, 1.0 parts by weight of N Ichino Rumorpholine, 3.0 parts by weight of silicone oil, and 4.0 parts by weight of pulp.

Next, the prepolymer stock solution was discharged onto an endless belt and uniformly coated with a doctor knife, and then passed through a steam tank for 2 minutes to foam, thereby producing a long polyurethane foam sheet with a thickness of 3 wrrrL.

Comparative Example 1 A prepolymer stock solution having the same composition as in Example 1 was used, except that propylene glycol was not blended. After discharging this onto an endless belt and uniformly applying it with a doctor knife, it was passed through a steam tank for 2 minutes. At least foam it to a thickness of 3? A long polyurethane foam sheet was obtained.

Then, the physical properties of the long polyurethane foam sheets of Example 1 and Comparative Example 1 were investigated, and the results were as shown in Table 1 below.

As is clear from the above table, the foamed sheet (Example 1) obtained by the method of the present invention using a prepolymer stock solution to which a modifier (propylene glycol) was added was the same as the foamed sheet obtained using a prepolymer stock solution to which no modifier was added. Compared to the foamed sheet (Comparative Example 1), the hardness was significantly improved and the shape retention was improved.

Example 2 0H6013 functional polyether polyol (trade name: Hybrox 3000, manufactured by Nippon Reichhold Co., Ltd.)
37 parts by weight of tolylene diisocyanate and 15 parts by weight of dehydrated molasses were mixed with 100 parts by weight, and stirred and reacted at 90°C for 2 hours until the amount of free NCO was 10%. After preparing a composition of polyether urethane prepolymer, 100% of this composition was prepared.
Weight part contains tin-based catalyst (product name: U28, manufactured by Nitto Kasei Co., Ltd.)
A urethane prepolymer stock solution was prepared by adding 0.6 parts by weight, 1.0 parts by weight of N-ethylmorpholine, and 2.5 parts by weight of silicone oil.

Next, the prepoly stock solution was discharged onto an endless belt and applied uniformly with a dotter knife, and then passed through a steam tank for 2 minutes to foam, thereby obtaining a long polyurethane foam sheet with a thickness of 5 Tm.

Comparative Example 2 A urethane prepolymer stock solution having the same composition as in Example 2 was used, except that no waste molasses was added. After discharging this onto an endless belt and applying it uniformly with a doctor knife, it was placed in a steam tank. to foam for 2 minutes,
A long polyurethane foam sheet having a thickness of 51 VL was obtained.

When the physical properties of the long polyurethane foam sheets of Example 2 and Comparative Example 2 were investigated, the results were as shown in Table 2 below.

As described in detail above, according to the present invention, it has a predetermined mechanical strength and rebound resilience, and has improved hardness to have excellent shape retention, and can be used as a material for clothing, interior decoration, or adhesive tape. It is possible to obtain a long polyurethane foam sheet at a low cost, which can be suitably used for industrial materials, acoustic materials such as speaker edge materials, and the like.

Claims (1)

[Claims] 1 A polyhydroxyl compound and an organic isocyanate are mixed and reacted with a modifier consisting of one or more of sugars, molasses, and blackstrap molasses to form a urethane prepolymer stock solution, and this is poured onto a continuously running base material. After applying,
A method for producing a long polyurethane foam sheet, which comprises introducing the sheet into a steam tank and foaming it.