JPH11115137A - Shape memory form or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To return to an original shape without retaining a folding line or wrinkle even in the case of folding or wrinkling a form or a polymer substance sheet by coating one or both surfaces of the form or the polymer sheet with crystalline urethane prepolymer and moisture curing it. SOLUTION: The shape memory form or sheet is obtained by coating one or both surfaces of a form or polymer sheet with crystalline urethane prepolymer and moisture curing it. The prepolymer is formed in a molecular arrangement for keeping order. A clear crystal structure is observed by an X-ray diffraction. The prepolymer is obtained by an urethane bond of a crystalline polyesterpolyol having a melting point and a multifunctional isocyanate. A coating amount of the prepolymer for coating a predetermined form or sheet is 10% or more per unit area of the predetermined form or sheet. The prepolymer is sufficiently moisture cured, and a moisture cured shape is a memory shape. If it is 10% or less, it is not returned to its original shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape memory paper or sheet, and more particularly, to a shape memory paper or sheet which can be folded and wrinkled by heating the folded or wrinkled paper to recover the original paper.

[0002]

2. Description of the Related Art Conventionally, various types of paper such as securities paper (stock certificates, securities, etc.), checks, bills, information industry paper (copy paper, computer paper, etc.), typewriter paper, vouchers, election voting paper, prepaid cards, etc. Although sheets are widely used, these papers or sheets are papers or sheets having no shape memory. JP-A-8-34067 is an example of the shape memory paper. This is a polymer obtained by molding a shape memory resin or a composition of a shape memory resin and an animal cellulose or synthetic polymer material sheet on a sheet.

[0003]

Conventionally, the paper and the synthetic polymer sheet used have no shape memory, so that if they are accidentally crumpled or bent, they will always be wrinkled even if they are restored. And folds remain. In particular, things of value per se, such as banknotes, securities, stock certificates, checks, and prepaid cards, may become invalid. Therefore, there is a demand for a sheet or sheet that can be returned to its original shape without wrinkles or folds even if it is folded.

[0004] In addition, at the time of election, voters write candidates in a ballot paper and then fold them in two.
It takes time to open the ballot when counting votes. By changing the voting paper to the shape memory sheet of the present invention, if the temperature is equal to or higher than the shape restoration temperature at the time of counting the votes, the voting paper will naturally open and the work of counting the votes can be omitted, which is desired.

An object of the present invention is to provide a paper or sheet which can return to its original shape without remaining creases or wrinkles even if it is bent or wrinkled, which is the above-mentioned conventional problem. It is to provide a storage sheet or sheet.

In order to solve the above-mentioned problems, the present inventors have proposed that a shape memory resin can be formed by forming a sheet from a crystalline urethane prepolymer in which a crystalline polyester polyol and a polyfunctional isocyanate are urethane-bonded, and curing the sheet with moisture. I found It has been found that even if this shape memory paper or sheet is bent or rolled, it can be restored to the original paper or sheet by heating to a temperature higher than the melting point of the polyester polyol as a raw material. It has been found that this crystalline urethane prepolymer is applied to paper or a sheet made of a vegetable cellulose or synthetic polymer substance sheet and cured by moisture, thereby solving the above problems and finding that it can be used for various purposes.

It has been found that the melting point of this crystalline polyester polyol is approximately the phase transition point of the moisture-cured resin. It has been found that this phase transition point is the temperature at which the deformed resin is restored.

[0008]

A first aspect of the present invention is a shape memory paper or sheet obtained by applying one or both sides of a crystalline urethane prepolymer to paper or a high-molecular material sheet and curing with moisture. A second invention is a shape memory paper or sheet obtained by laminating a paper or a synthetic high molecular material sheet with a crystalline urethane prepolymer and curing it by moisture. According to a third aspect of the present invention, a crystalline urethane prepolymer having terminal isocyanate groups obtained by reacting a crystalline polyester polyol with a polyfunctional isocyanate compound is coated on paper or a polymer substance sheet on one or both sides and moisture-cured. The resulting shape memory paper or sheet.

A fourth invention is to laminate a paper or a synthetic polymer material sheet with a crystalline urethane prepolymer having both terminal isocyanate groups obtained by reacting a crystalline polyester polyol with a polyfunctional isocyanate compound, and then curing the moisture or moisture. This is a shape memory sheet or sheet obtained by the above. A fifth invention is the shape memory paper or sheet according to the third or fourth invention, wherein the crystalline polyester polyol has a melting point of 0 ° C. or more. In a sixth aspect, the equivalent ratio of the OH group of the crystalline polyester polyol to the NCO of the polyfunctional isocyanate is 1: 1.01.
The shape memory paper or sheet according to any one of claims 3 to 4, characterized in that the shape memory paper or sheet is obtained by reacting at a pressure of from 10 to 10 and applying it to paper or a synthetic polymer material sheet or laminating and then curing with moisture.

A seventh invention is characterized in that the crystalline urethane prepolymer is applied or laminated on paper and a polymer substance sheet in an amount of 10% by weight or more.
6 is a shape memory sheet or sheet according to the invention. An eighth invention is the shape memory paper or sheet according to the first to seventh inventions, which is used for securities, ballot papers, and cards.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a shape memory sheet or sheet of the present invention will be specifically described. The crystalline urethane prepolymer used in the present invention has an ordered molecular arrangement, a clear crystal structure is observed by X-ray diffraction, and a crystalline polyester polyol having a melting point and a polyfunctional isocyanate are formed by a urethane bond. It is obtained. The crystalline polyester polyol is a reaction product of one or more aliphatic polycarboxylic acids and one or more aliphatic polyols. In consideration of the temperature at which the shape memory resin recovers, the melting point of the crystalline polyester polyol is desirably 0 ° C. or higher. If the melting point is lower than 0 ° C., the resin recovers its original shape at room temperature and loses the function of the shape memory resin.

The molecular weight of the crystalline polyester is desirably 100 or more, preferably 1,000 or more.

The above-mentioned aliphatic polycarboxylic acids include, for example, oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonamethylene dicarboxylic acid, decamethylene dicarboxylic acid, Undecamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid and the like can be mentioned.

The above aliphatic diols include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14
-Tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol and the like.

In the present invention, the polyfunctional isocyanate compound includes 4,4'-diphenylmethane diisocyanate (MDI), p-phenylenediisocyanate, tolylene diisocyanate (TDI), 1,5-naphthalenediisocyanate (NDI), 4'-diphenylene diisocyanate, 1,5-octylene diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated MDI, hydrogenated XDI, etc. Can be OH of crystalline polyester polyol
Ratio of the NCO group to the NCO group of the polyfunctional isocyanate is 1:
When the ratio is 1.01 or less, the shape does not return to the original shape because the number of moisture-cured polymer crosslinking points is small. If the ratio is more than 1:10, the unreacted isocyanate remains in excess, so that the shape is not restored.

The paper used in the present invention includes art paper, imitation art paper, coated paper, high quality paper, medium quality paper, hard paper, kraft paper, roll paper, glassine paper,
There are industrial photosensitive base paper, tracing paper, Kent paper, tissue paper, cardboard, carbonless paper, imitation paper, copy paper and the like.

The synthetic polymer sheet used in the present invention includes polypropylene, polyvinyl chloride, polystyrene,
Examples include a sheet such as polyethylene terephthalate or a woven fabric such as a nonwoven fabric.

The reaction for synthesizing the crystalline urethane prepolymer is carried out by putting a predetermined amount of the crystalline polyester polyol into a reaction vessel and heating the mixture in a heater capable of controlling the temperature at a uniform temperature.
The mixture is stirred while being heated to 135 ° C., preferably 110 ° C. to 130 ° C., and is sufficiently dried in a vacuum or by blowing dry nitrogen. Next, a predetermined amount of the polyfunctional isocyanate compound (D) is added, and dry nitrogen is blown into the reaction vessel or the inside of the reaction vessel is evacuated to carry out the reaction while preventing moisture from entering. This reaction does not require a solvent such as methyl ethyl ketone, methyl isobutyl ketone, toluene, butyl acetate, and ethyl acetate, but a solvent may be used. In this case, the reaction temperature must be lower than the boiling point of the solvent.

Next, the amount of the obtained crystalline urethane prepolymer applied to a predetermined paper or sheet is 10% or more, preferably 50% or more per unit area of the predetermined paper or sheet. I do. This is fully moisture cured. This moisture-cured shape is the memorized shape.
If it is less than 10%, the strength of the paper or sheet is too strong to return to the original shape.

The conditions for moisture curing are preferably a temperature of 0 ° C. or more, a humidity of 10% or more, and a week or more. If it is below this condition, it is considered that the curing does not occur sufficiently and the shape is not stored.

The shape to be memorized is not limited to a flat shape, and the shape when moisture-cured is memorized. Therefore, it is possible to memorize any shape such as a cylindrical shape and a conical shape.

Next, even if the sheet or sheet storing this shape is bent, rounded, or crumpled, it is placed in an oven, liquid, or the like and heated to a temperature higher than the phase transition point of the shape memory resin. Return to the shape. This phenomenon is
It happens repeatedly.

The phase transition point is a temperature at which the shape memory resin returns to its original shape after being bent or stretched. This shape memory resin retains its shape even when it is bent or stretched below the phase transition point, but when the temperature exceeds the melting point of the polyester used as the raw material, that is, the temperature above the phase transition point, the polyester part softens. And return to the original shape.

In general, rubber and thermoplastic have a phase transition point. That is, at a certain temperature or higher, soft rubber-like elasticity is exhibited, but at a temperature lower than that temperature, the movement of the polymer chain freezes and solidifies, indicating a hard plastic state.
The temperature is called a phase transition point (glass transition point). In general, when a force at room temperature is applied, it is flexible and well deformed, but an elastic body that returns to its original shape when the force is removed is called rubber. On the other hand, even if force is applied at room temperature, it is very difficult to deform, and if you try to forcibly deform it, you can not do it, but the deformation rate is generally small, and if you use it greatly, it will break or break hard Call it plastic.
Even if plastic can be deformed, it is difficult to return to its original shape.

This phenomenon can be explained by the fact that what is called rubber has a much lower phase transition point than room temperature, and what is called plastic has a phase transition point higher than room temperature. It is due to that.

In general, a shape memory resin is a substance that deforms into a resin at a temperature below the phase transition point and into a rubber at a temperature above the phase transition point. That is, the phase transition point of the shape memory resin is higher than normal temperature. In the present invention, the melting point of the crystalline polyester polyol used as the raw material is the phase transition point of the resin obtained by moisture-curing the crystalline urethane prepolymer reacted with the polyfunctional isocyanate. I found it back. In other words, the present shape memory sheet, when the moisture-cured resin is below the phase transition point,
It has a mechanism inside to keep its shape when cured. The shape memory sheet is wrinkled or bent at a temperature below the phase transition point. Furthermore, when it is heated above the phase transition point, it has the property of returning from a wrinkled or bent shape to a moisture-cured prototype. In other words, it utilizes the property that the moisture-cured resin changes into a property similar to rubber at a phase transition point or higher.

In general, a shape memory resin is a substance that deforms into a resin at a temperature below the phase transition point and into a rubber at a temperature above the phase transition point. That is, the phase transition point of the shape memory resin is higher than normal temperature.

[0028]

The present invention will be described below with reference to examples.

Synthesis Example 1 1 equipped with a stirrer, temperature sensor, heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. Crystalline polyester polyol (consisting of succinic acid and 1,8-octanediol and having alcohol groups at both ends, Mw = 17000, Mn = 9000, hydroxyl value 30.7, acid value measured by GPC (gel permeation chromatography) 100 parts by weight After dehydration, 65 parts by weight of a polyfunctional isocyanate compound (4,4'-diphenylmethane diisocyanate) is added (OH group of crystalline polyester polyol and polyfunctional isocyanate are added). The equivalent ratio of NCO groups is 1: 2.2)
Then, the reaction is carried out at 120 ° C. for about 5 hours while blowing dry nitrogen.

The phase transition point of the obtained crystalline urethane prepolymer was measured by DSC (SSC52 manufactured by Seiko Instruments Inc.).
00).

Synthesis Example 2 1 equipped with a stirrer, temperature sensor, heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. Crystalline polyester polyol (consisting of succinic acid and 1,12-octanediol, having alcohol groups at both terminals, Mw = 17000, Mn = 9300, hydroxyl value 28.3, acid value 1 as measured by GPC (gel permeation chromatography). 100 parts by weight After dehydration, 100 parts by weight After dehydration, 65 parts by weight of a polyfunctional isocyanate compound (4,4'-diphenylmethane diisocyanate) was added (the OH group of the crystalline polyester polyol and the NCO of the polyfunctional isocyanate were added). The equivalent ratio of the groups is 1: 2.2)
Then, the reaction is carried out at 120 ° C. for about 5 hours while blowing dry nitrogen.

The phase transition point of the obtained crystalline urethane prepolymer was determined by DSC (SSC52 manufactured by Seiko Instruments Inc.).
00).

Synthesis Example 3 1 equipped with a stirrer, temperature sensor, heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. Crystalline polyester polyol (consisting of succinic acid and 1,10-decanediol, having alcohol groups at both terminals, Mw = 17200, Mn = 9500, hydroxyl value 28.3, acid value by GPC (gel permeation chromatography) measurement) 1.1, the melting point is 70 ° C. based on DSC) 100 parts by weight After dehydration, 65 parts by weight of a polyfunctional isocyanate compound (4,4′-diphenylmethane diisocyanate) is added (the OH group of the crystalline polyester polyol and the polyfunctional isocyanate are added). The equivalent ratio of NCO groups is 1: 2.2)
Then, the reaction is carried out at 120 ° C. for about 5 hours while blowing dry nitrogen.

The phase transition point of the obtained crystalline urethane prepolymer was determined by DSC (SSC52 manufactured by Seiko Instruments Inc.).
00).

Synthesis Example 4 1 equipped with a stirrer, temperature sensor, heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. A crystalline polyester polyol (consisting of succinic acid and 1,8-octanediol, having both terminal alcohol groups, and Mn = 9000, Mw = 17000, Mw / Mn = 1.91 as measured by GPC (gel permeation on chromatography); 100 parts by weight After dehydration, 130 parts by weight of a polyfunctional isocyanate compound (tolylene diisocyanate) was added (equivalent ratio of the OH group of the crystalline polyester polyol to the NCO group of the polyfunctional isocyanate was 1: 100). 2.2)
Then, the reaction is carried out at 120 ° C. for about 5 hours while blowing dry nitrogen.

The phase transition point of the obtained crystalline urethane prepolymer was measured by DSC (SSC52 manufactured by Seiko Instruments Inc.).
00).

Synthesis Example 5 1 equipped with a stirrer, temperature sensor, heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. 100 parts by weight of non-crystalline polyester polyol (DYNACOLL7 130 manufactured by Huls, melting point 30 ° C.) 100 parts by weight After dehydration, 65 parts by weight of a polyfunctional isocyanate compound (4,4′-diphenylmethane diisocyanate) was added (OH of non-crystalline polyester polyol). Ratio of NCO group to NCO group of polyfunctional isocyanate is 1: 2.2)
Then, the reaction is carried out at 120 ° C. for about 5 hours while blowing dry nitrogen.

The phase transition point of the obtained crystalline urethane prepolymer was determined by DSC (SSC52 manufactured by Seiko Instruments Inc.).
00). Synthesis Example 6 1 equipped with a stirring device, a temperature sensor, a heating and vacuum device
Each of the following compositions was mixed in a 000 ml four-necked flask, and dehydrated at 120 ° C. for about 2 hours while stirring in a vacuum. 100 parts by weight of liquid polyester polyol (DYNACOLL7210 manufactured by Huls) After dehydration, 65 parts by weight of a polyfunctional isocyanate compound (4,4′-diphenylmethane diisocyanate) was added (OH group of liquid polyester polyol and NCO group of polyfunctional isocyanate) Is equivalent ratio of 1: 2.2),
The reaction is performed at 120 ° C. for about 5 hours while blowing dry nitrogen.

Examples 1 to 4 The crystalline urethane prepolymers obtained in Synthesis Examples 1 to 4 were applied to fine paper (basis weight: 85 g / m ² ) and tracing paper (basis weight: 40 g / m ² ). Is applied on one or both sides with respect to the weight per unit area. The sheet is placed in a thermo-hygrostat at a temperature of 20 ° C. and a humidity of 65% for 24 hours, and is moisture-cured to obtain a shape memory sheet. The obtained shape memory paper was folded to form wrinkles. The sheet was placed in an oven at 120 ° C. and heat-treated for 3 minutes. Table 1 shows the results.

Example 5 The crystalline urethane prepolymer of Synthesis Example 1 was coated on a high-quality paper (basis weight: 85 g / m ² ) (coating amount: 85 g / m ² ).
Rolled and cured sufficiently in a constant temperature and humidity chamber at a temperature of 20 ° C and a humidity of 65%, then creased and creased, and then placed in an oven at 120 ° C for 3 minutes. The shape memory paper became cylindrical when cured by moisture. Restored.

Example 6 A lacing paper (basis weight: 40 g / m ² ) was laminated on the crystalline urethane prepolymer of Synthesis Example 1 (coating amount: 40 g / m ² ), and the temperature was 20 ° C. and the humidity was 65%. After sufficiently moisture-curing in a thermo-hygrostat, creased and creased, and then placed in a 120 ° C. oven for 3 minutes, the shape memory paper returned to the moisture-cured shape. Comparative Examples 1-2 The urethane prepolymers obtained in Synthetic Examples 5-6 are coated on high-quality paper and tracing paper on one side and on both sides with 50, 100, 500 parts by weight of 100 parts by weight of paper. The sheet is placed in a high-temperature, high-humidity room at a temperature of 20 ° C. and a humidity of 65% for 24 hours to obtain a moisture-cured sheet.

The obtained paper was folded to form wrinkles. This paper was placed in a 120 ° C. oven and subjected to a heat treatment for 3 minutes. Table 1 shows the results.

[0043]

[Table 1]

[0044]

According to the shape memory paper or sheet of the present invention, a crystalline urethane prepolymer is applied to one or both sides of a paper or a synthetic polymer sheet, and is moisture-cured in a desired shape to be memorized. Resin can be easily obtained. Therefore, by applying shape memory resin to securities paper, checks, banknotes, information industry paper, typewriter paper, vouchers, voting paper, prepaid cards, etc. By heating above the point, the original shape can be easily restored.

Claims (8)

[Claims] 1. A shape memory paper or sheet obtained by applying a crystalline urethane prepolymer to one or both sides of paper or a polymer material sheet and curing with moisture. 2. A shape memory paper or sheet obtained by laminating a paper or a synthetic polymer material sheet with a crystalline urethane prepolymer and curing it by moisture. 3. A method in which a crystalline polyester polyol and a polyfunctional isocyanate compound are reacted with each other to form a crystalline urethane prepolymer having both terminal isocyanate groups on one or both sides of paper or a polymer sheet, and then moisture-cured. Shape memory paper or sheet. 4. A sheet obtained by laminating a paper or a synthetic polymer material sheet with a crystalline urethane prepolymer having both terminal isocyanate groups obtained by reacting a crystalline polyester polyol and a polyfunctional isocyanate compound, and then curing by moisture. Shape memory paper or sheet. 5. The shape memory paper or sheet according to claim 3, wherein the melting point of the crystalline polyester polyol is 0 ° C. or higher. 6. An equivalent ratio of OH groups of the crystalline polyester polyol to NCO of the polyfunctional isocyanate of 1: 1.0.
The shape memory paper or sheet according to claim 3, wherein the shape memory paper or sheet is obtained by reacting at 1 to 10 and applying moisture to the paper or synthetic polymer material sheet or laminating and then curing. 7. The shape memory paper or sheet according to claim 1, wherein the crystalline urethane prepolymer is applied or laminated in an amount of 10% by weight or more to the paper and the polymer substance sheet. 8. The shape memory paper or sheet according to claim 1, which is used for securities, voting paper, and cards.