JPS5836104B2 - Acrylic Keyboard Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an acrylic nonwoven fabric manufactured by a completely unprecedented melt extrusion method using a polymer containing acrylonitrile as its main component (hereinafter abbreviated as acrylic polymer). Concerning the manufacturing method.

Conventionally, the production of long-fiber nonwoven fabrics using acrylic polymers
Filaments are produced from an acrylic polymer solution by a conventional wet or dry spinning method, and this is formed into a web by an appropriate means, followed by spraying, printing, or coating with a binder solution to create partial adhesion between the filaments. The typical method is to produce a nonwoven fabric.

However, such conventional methods use a large amount of acrylic polymer solvent and go through extremely complicated wet or dry processes.
It was extremely disadvantageous both technically and economically.

The inventors of the present invention have conducted extensive research in order to eliminate the drawbacks of the prior art as described above and to develop a method for manufacturing acrylic nonwoven fabric with high efficiency. The inventors of the present invention have completed the present invention by discovering that it is possible to produce a desired nonwoven fabric with high efficiency by a different method, that is, by melt extruding an acrylic polymer.

That is, the present invention provides an acrylic polymer (■) and a compound having a solubility in water of 5 g/100 ml or more at 20° C. and a solid state at 20° C. according to the following formula (1) (where Y is a water-soluble solid matter weight (parts by weight relative to 1 part by weight of polymer).

), and the following formula (2) (where A is the acrylonitrile content in the polymer (% by weight), Z is the moisture content (parts by weight relative to 1 part by weight of the polymer)
shows.

) of water (III) at 140°C to 23°C.
The acrylic structure is melted by heating to 0°C and extruded through a die with a slotted orifice to form an acrylic structure, which is then shaken onto a movable net to form a sheet, treated with hot water, and then dried. This is a method for producing acrylic nonwoven fabric.

In the present invention, the acrylic polymer refers to a polymer containing 30 weight φ or more of acrylonitrile.

Monomers other than acrylic acid or methacrylic acid include methyl, ethyl, butyl, 2-ethylhexyl ester, vinyl acetate, acrylamide,
Neutral monomers such as methacrylonitrile, vinyl ethyl ether, allyl alcohol, vinyl chloride, vinylidene chloride, ethylene sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, acrylic acid, methacrylic acid or its ammonium salt, sodium salt Typical monomers include acidic monomers such as , potassium salts, and basic monomers such as vinylpyridine, N,N-dimethylaminoethyl methacrylate, and vinylimidazole. , but is not limited only to the above monomers.

Further, the polymer that can be used in the present invention may be a mixed polymer of two or more types.

Next, in the present invention, the acrylic structure refers to the acrylic polymer (I) and the solubility in water at 20° C. as described above. 9/1 00 1 or more, containing Compound (II) which is solid at 20°C in an amount represented by the following formula (1), and containing an amount of water content represented by the following formula (2). After heating the mixed composition containing the mixture to 140° C. to 230° C. to melt it, extruding it through a die having a slit-like orifice to form a continuous or thin product or tape cut into a desired length. It refers to a shaped object or a sheet shaped object.

Z: Moisture content (parts by weight relative to 1 part by weight of polymer) Y: Weight of water-soluble solids (parts by weight relative to double parts of polymer) A: Acrylonyl content in polymer (weight) These structures Surprisingly, the fibers can be defibrated into fine continuous fibers by hot water treatment, and by laminating these fibers into a sheet, a nonwoven web can be easily obtained.

When manufacturing the above acrylic structure, it is important to keep the amount of water used at that time within the range of the following formula.

(However, Z is the water content (parts by weight relative to 1 part by weight of the polymer), A is the acrylonitrile content in the polymer (weight φ)) Considering the effects of water, for water-soluble compounds, On the other hand, for acrylic polymers,
Due to the plasticizing effect, a mixed composition of a water-soluble compound and an acrylic polymer becomes fluid and moldable when heated under pressure.

Therefore, if the amount of water is less than the amount shown by the above formula, the plasticizing effect and dissolving effect will be reduced, the fluidity of the mixed composition will be poor, and hot molding will be difficult.

Another effect of water on the acrylic polymer is that the amount of water in excess of that required to plasticize the acrylic polymer acts as a foaming agent that boils down foaming during molding.

Therefore, if the amount of water exceeds the amount indicated by the above formula, the instantaneous evaporation of water will become intense, the structure will be torn apart, and it will be difficult to obtain a continuous product.

Next, regarding a compound that has a solubility in water of 5g7100ml or more at 20°C and is solid at 20°C, a structure obtained from a composition containing the compound may be subjected to hot water treatment. It is truly surprising that some or all of the above compounds are removed by
It is defibrated into extremely fine single filaments.

That is, when an acrylic structure obtained by discharging a composite material containing the above compound from a single-hole die is immersed in hot water for a short time, a fiber aggregate (web) with extremely fine fineness can be obtained. be.

This effect largely depends on the content of the above compounds.

If the content of the above-mentioned compound is less than 10φ of the acrylic polymer, even if the obtained structure is treated with hot water for a long time, it will be difficult to defibrate into uniform fine fibers, and therefore it will be difficult to defibrate into uniform fine fibers. becomes difficult to manufacture.

As the content of the above compounds increases, the fineness of the defibrated single fibers tends to become finer. However, if the above compounds are not completely eluted, the texture after drying of the web will become hard and the paper It has a similar texture.

Further, as the elution of the above compound increases, it becomes disadvantageous in terms of recovery. Therefore, it is preferable for the content of the above compound to be within the range of the following formula in order to obtain a suitable product industrially.

0. 1 <Y< 1. 5 (where Y is the weight of the water-soluble solids (parts by weight relative to 1 part by weight of the polymer)) Next, the unique effects of the above compound will be described.

What is truly strange is that the above-mentioned compound has an effect of suppressing foaming caused by water in hot-melt extrusion products.

For example, a tape obtained using a slit-type die from a composite in which the above compound does not exist will be a continuous tape with striped patterns that are traces of water bubbling, whereas a tape obtained from a composite that does not contain the above compound will be a continuous tape with striped patterns that are traces of water bubbling. The resulting tape is a uniform continuous tape with relatively few striped patterns.

The above compound preferably used in the present invention has a solubility in water at 20°C of 5.97100 ml or more,
It is preferable that it is solid at 20° C. and has high heat resistance stability.

When a compound that is liquid at 20°C is used in the present invention, the resulting structure will not be opened into single fibers by hot water treatment, so a compound that is solid at 20°C is used. It is important to do so.

Examples of the above compounds include water-soluble organic polymers such as polyacrylamide, polyvinyl alcohol, partially saponified polyvinyl acetate, polyethylene oxide, partially modified polyacrylonitrile, CMC starch, and sucrose, as well as magnesium sulfate, sodium sulfate, and sulfuric acid. Alkali metals such as potassium and magnesium phosphate, sulfates of alkaline metals,
Although water-soluble inorganic compounds such as phosphates are used, the present invention is not limited only to the above-mentioned compounds.

The optimum extrusion temperature of the present invention needs to be appropriately selected depending on the composition of the polymer, the degree of polymerization, and the type, amount, and moisture content of the water-soluble compound, but is generally 140°C or lower.
The extrusion pressure is high, making it difficult to take out the product continuously.

Although there is no need to specifically limit the upper limit of the extrusion temperature, it is desirable to keep it within 230°C from the viewpoint of coloring the product.

Next, regarding the shape of the die in the present invention,
Although there is no need to specifically limit this, a slit type is preferable from the viewpoint of continuous extraction.

The atmosphere in which the heated molten composite is discharged from the die has a subtle effect on the texture of the resulting product, so it is necessary to select the most suitable atmosphere depending on the desired continuous structure. However, any of atmospheric pressure, pressurized conditions, and even a heated atmosphere can be used.

The manufacture of acrylic structures can be completed by continuously taking out the discharged acrylic structures, but it is necessary to keep in mind that the texture and form of the product will differ depending on the draft at the time of taking out. There is.

In other words, if the draft is small, water foams more actively and tends to form a foaming structure.

For this reason, it is more convenient to make the draft thicker than 1 and take out the water in a direction that suppresses foaming of the water, in order to obtain a continuous and uniform product.

In carrying out the present invention, there is no problem with further applying treatments such as post-stretching or heat compression to the acrylic structure thus obtained.

Next, regarding the hot water treatment of the acrylic structure, the structure after the removal process is shaken down in the state of X into a sheet in the form of a net.

Of course, the structure may be cut to an appropriate length before being shaken off.

A hot water shower is sprayed onto the sheet-like structure transferred onto the net to elute water-soluble compounds.

The hot water shower conditions include the degree of elution of water-soluble compounds,
Depending on the operating time, at least one portion of the hot water should be heated to 10% to improve the uniformity of the product web.
It is preferable to set the temperature to 0°C.

In addition to the hot water shower, it is also possible to adopt a method of immersing the sheet-like Acnor structure in a hot water bath.

After the elution operation of the water-soluble compound is completed as described above, the present invention is completed by attaching a binder liquid if necessary and drying.

The method for preparing the mixed composite in the present invention can be carried out by any method, taking into account that water is used with the two IJ groups during extrusion molding under high temperature and pressure, but any method can be used. Mixed compositions can be used to improve productivity.
If the residence time in the extruder is shortened, water utilization will not proceed sufficiently, making stable operation difficult.

Therefore, during high-speed production, it is preferable to use a water-utilizing product in which the two groups and water are available to some extent.

The water conservancy or entity applies the mixture of the polymer and water under autogenous pressure,
Alternatively, it can be obtained by heating to 100° C. or higher under pressure.

Most advantageously, the usable method for producing the composition of the present invention is that an acrylic polymer produced by underwater polymerization is dehydrated and then dried under autogenous pressure at a temperature of 100° C. or higher to a predetermined moisture content. This is a method of adding water-soluble compounds to food.

In carrying out the present invention, heat-resistant stabilizers, weather-resistant stabilizers,
It is also possible to use colored pigments and other fillers.

Examples of the present invention will be shown below.

All parts and weights in the examples refer to parts by weight.

Example 1 A copolymer slurry of acrylonitrile/methyl acrylate/styrene/sodium sulfonate (copolymerization ratio: 93/6.5/0.5 weight ratio) was produced by aqueous suspension polymerization.

This polymer was dried, dissolved in dimethylformamide,
R. L. Cleland's equation (Journal of Polymer Science, Vol. 17, p. 473, 1955) [η
]=2.43×10′MO·75, the average molecular weight was determined and divided by the molecular weight of acrylonitrile to determine the average degree of polymerization, which was 1050.

The slurry was filtered, dried at 128°C, and apparently
A dried polymer was obtained.

The water content in this polymer is Z/A=O. It was O O 4 2.

Polyethylene oxide (degree of polymerization: 600,000) was mixed with this apparently dry polymer to obtain the composition shown below.

A: y=o B: Y=0.1 C: Y=0.8 These compositions were set at 180°C and 407II
! 1×0.1N. The hopper of the extruder is equipped with a slit-type orifice of
A constant nitrogen pressure was applied and the mixture was discharged into the atmosphere.

The extrusion pressure at this time was 50 Ky/cr/t.

The discharged melt was taken out and heated at 40°C with a draft of 1.3.
It was wound up at a winding speed of m/m.

In the resulting structure, (A) was a tape with a striped pattern, (C) was a tape with relatively few stripes, and (C) was a uniform tape.

When the above structure was immersed in 100°C hot water for 5 minutes,
The material was opened into fine fibers.

A. The mouth part continued to be immersed for a longer time, but there was no change in the part A. Although the mouth part became slightly loosened, it was not opened into single fibers.

Two layers of the tape (C) were stacked and continuously shaken out into a sheet onto a movable net.

The tape on the movable net was sprayed with a 100°C hot water shower to elute the polyethylene oxide, and then dried in a drum dryer at 120°C, resulting in a nonwoven fabric with a flexible feel. obtained continuously.

Approximately 10% of the polyethylene oxide remained in this nonwoven fabric, and the nonwoven fabric had sufficient strength even though no special binder was used.

The basis weight of this nonwoven fabric is s o g 7crd and the tearing length is 16K.
m, and the cantilever bending strength was 57w1.

The average fineness of the structure fibers of this nonwoven fabric was 1.0 denier, and the average strength was 1.2 g/d.

Example 2 The copolymer shown below was manufactured, the composition shown in Table 1 was prepared, and the apparatus of Example 1 was used to discharge and take out (draft 1.3).

The resulting tape was then heated to 50M. It was cut into long pieces and shaken down in a sheet form onto a movable net connected to a water-soluble compound elution tank.

The water-soluble compound elution tank was maintained at 10° C., and the web from the main elution tank was dried in a drum dryer.

Table 1 shows the web state of the obtained nonwoven fabric, and the average fineness and average strength of the structural fibers.

Example 3 In Example 1, the structure C was discharged into a heated gas at 100° C., and the obtained structure was treated in the same manner as in Example 1 to produce a nonwoven fabric.

The obtained nonwoven fabric had a harder feel than that of Example 1.

Comparative Example 1 Acrylic structures were produced in the same manner as in Example 1 except that the extrusion temperature was changed to 235·c, but all of the obtained structures were significantly colored.

Claims (1)

[Claims] 1 A polymer (I) containing acrylonitrile as a main component, and a compound (II) having a solubility in water at 20°C of 5 g/100771l or more and being solid at 20°C.
contains the amount shown by the following formula (1), and the following formula (2)
A composition containing water (II) in an amount shown by 140
The acrylic structure is melted by heating to ℃ to 230℃, extruded through a die with a slit-shaped orifice, and shaped into an acrylic structure.Then, this is shaken onto a movable net to form a sheet, which is then treated with hot water and then dried. A method for producing an acrylic nonwoven fabric characterized by
is the acrylonitrile content (% by weight) in the polymer, Z is the moisture content (parts by weight relative to 1 part by weight of the polymer)