JPH02259189A - Sheet-shaped molded product with excellent alkali resistance - Google Patents

Abstract

PURPOSE:To provide the subject formed product excellent in liquid retentivity, etc., useful for filters, industrial wipers, etc., containing a specified amount of fiber made from a composition containing polysulfone and/or polyethersulfone and polyvinyl chloride. CONSTITUTION:For example, when wet spinning process is to be used, (1) >=15wt.% of polysulfone and/or polyethersulfone and (2) >=20wt.% of polyvinyl chloride are dispersed in a solvent such as dimethylacetamide to prepare a spinning dope, which is then extruded through a spinneret into a coagulating bath (pref, water), thus producing PSV fiber. The fiber is then chopped to an appropriate length. Thence, (A) >=50 (pref. 50 to 90)wt.% of the resulting chopped fiber and (B) binder fiber <=125 deg.C in heat fusing temperature (e.g. polyethylene-based fiber) are put to papermaking process using pref. a wet system (a process where both the fibers are dispersed in water and put to papermaking), thus obtaining the objective sheet like formed product.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sheet-like molded product useful for filters requiring alkali resistance and battery separator-1 industrial wipers.

<Prior Art> In recent years, the applications of sheet-like molded products have expanded, and they are now widely used in various industrial applications, such as industrial filters 1, battery separators, and industrial wipers.

As is well known, the sea-shaped molded products used for filters, separators, wipers, etc. have appropriate air permeability, liquid permeability,
Performance such as appropriate strength, thickness, density, and high liquid retention properties are required, and with the recent advancement of industry, chemical resistance is also required. For example, waste acid and waste alkali treatment filters, battery separators, and the like are required to have a high degree of chemical resistance that hardly dissolves or deteriorates even when used in strong acid or strong alkaline solutions.

However, although conventional sheet-like molded products such as spunbond nonwoven fabrics, dry nonwoven fabrics, and wet nonwoven fabrics have excellent chemical resistance, they are insufficient in terms of air permeability, liquid permeability, liquid retention, paper strength, etc. On the other hand, although it has sufficient air permeability, liquid permeability, and liquid retention, it does not have sufficient chemical resistance.Currently, sheet-shaped molded products with satisfactory alkali resistance have not been replaced. be.

In particular, battery separators are desired to be improved as they are required to have excellent alkali resistance at high temperatures and high liquid retention.

<Problems to be Solved by the Invention> The present invention provides a sheet-like molded product with excellent alkali resistance, and is suitable for use in industrial filters, industrial wipers, etc. that require alkali resistance, especially at high temperatures, and also has liquid retention properties. The object of the present invention is to provide a sheet-like molded product useful as a battery separator by increasing the

<Means for Solving the Problems> The present invention provides fibers 50 made of a composition containing at least 15% by weight of polysulfone and/or polyethersulfone and at least 20% by weight of polyvinyl chloride.
It is a sheet-like molded product with excellent alkali resistance consisting of % by weight or more.

The shape of the sheet-like molded product of the present invention may be dry or wet nonwoven fabric, paper, knitted fabric, etc., and the best choice can be made depending on the application. For example, woven fabrics are most suitable for industrial filter applications in terms of improving the strength of molded products, and for battery separators, paper made by wet papermaking is most desirable from the standpoint of uniformity.

The sheet-like molded product of the present invention must contain at least 50% by weight of fibers made of a composition containing at least 15% by weight of polysulfone and/or polyethersulfone and at least 20% by weight of polyvinyl chloride. It is.

At least 15% by weight of polysulfone and/or polyethersulfone, at least 20% by weight of polyvinyl chloride
Fibers (hereinafter referred to as PSv fibers) composed of a composition containing % by weight have excellent alkali resistance and high liquid retention properties. Therefore, a sheet-like molded product containing PSv fiber as a main component has sufficient alkali resistance and liquid retention, and the content of PSV fiber in the sheet-like molded product is 5.
If the amount is 0% by weight or more, the object of the present invention can be achieved.

As mentioned above, there are nonwoven fabrics, paper, knitted fabrics, etc. as sheet-like molded products whose main component is PSv fibers, but in the case of non-woven fabrics or paper, it is possible to give the strength of the sheet-like molded product by heat fusion. This is preferable in terms of maintaining alkali resistance. Although it is possible to obtain a sheet-like molded product by thermally fusing the PSv fibers themselves, it is possible to eliminate not only the voids in the PSV fibers themselves but also the voids in the resulting sheet-like molded product to improve liquid retention in the sheet-like molded product. This results in loss of sexuality. For this reason, it is desirable to mix appropriate binder fibers and perform heat-fusion molding.

The binder fiber used in the sheet-like molded product of the present invention has a heat-fusion temperature of 125°C or lower, preferably 120°C or lower, and the mixing ratio thereof is 10 to 50% by weight, preferably 15 to 50% by weight. It's heavy.

If the heat fusion temperature of the binder fiber exceeds 125℃, ps
It is close to the heat fusion temperature of V fibers, and the psv during heat fusion molding.
The fibers also cause thermal fusion, impairing the liquid retention properties of the resulting sheet-like molded product. If the blending ratio of binder fibers is less than 10% by weight, the strength of the resulting sheet-like molded product will be insufficient. Even if the blending ratio of binder fibers is less than 10% by weight, it is possible to maintain the strength of the sheet-like molded product by setting the heat-fusion molding temperature high, but on the other hand, it reduces the voids of the sheet-like molded product and reduces liquid retention. This results in loss of sexuality. As described above, the heat fusion temperature and mixing ratio of the binder fibers are taken into consideration from the relationship between the strength and liquid retention properties of the resulting sheet-like molded product.

Binder fibers used in the sheet-like molded product of the present invention include polyethylene fibers and polyvinyl chloride fibers, but it is preferable that these binder fibers also have alkali resistance, and the resulting sheet-like molded product has alkali resistance. There is no particular limitation as long as it satisfies the following.

When used as a knitted fabric, the above-mentioned hinder fibers are not necessarily required.

Other components of the sheet-like molded product of the present invention are not particularly limited as long as they satisfy the alkali resistance and liquid retention properties of the sheet-like molded product, but those having alkali resistance are preferred, such as polyethylene Examples include fibers such as , polypropylene, and polyvinyl chloride.

It is important for the sheet-like molded product of the present invention to have alkali resistance. Specifically, when immersed in a 30 wt% KOI + aqueous solution, the fiber loss after 1 hour in normal pressure boiling is 2.0 wt% or less. This value is lower than the value of a nonwoven fabric made of polypropylene fibers measured by the same method.

Further, the sheet-like molded product of the present invention has a high liquid retention property, and as a guideline, the value determined by the following measurement method is 220% by weight or more. This liquid retention property is obtained not only by the voids in the sheet-like molded product itself, but also by the voids in the PSV fiber itself, and exhibits an excellent effect in applications requiring high liquid retention property.

Evaluation method for liquid retention (weight %) of sheet-like molded product: Cut out three test pieces of 5 cm x 5 cm from any part of the sheet and weigh them (old). After soaking this test piece in water (20° C.) for 1 hour, a droplet was thoroughly cut off, the weight (wi) was measured, and the weight (wi) was calculated using the following formula.

Furthermore, for the purpose of further improving the liquid retention property, it is possible to subject the sheet-like molded product of the present invention to surface treatment with a surfactant, etc., and the liquid-retention property of the sheet-like molded product of the present invention can be further improved. .

The PSV fiber used in the sheet-like molded product of the present invention is prepared by dimethylacetamide, a composition containing polysulfone and/or polyethersulfone, and polyvinyl chloride.
It is obtained by dissolving and dispersing it in dimethylformamide, dimethyl sulfoxide, or acetone, and forming the fiber into fibers, preferably by a wet spinning method.

The composition of PSv fibers includes polysulfone and/or polyethersulfone, polyvinyl chloride, and if necessary, other polymers may be mixed, but the fiber contains at least 15% by weight of polysulfone and/or polyethersulfone. It is necessary to contain

Polysulfone and polyethersulfone, which are the constituent components of PSv fiber, have the molecular structure shown below.
The degree of polymerization is not particularly limited.

Polysulfone; H3 Polyethersulfone; When the content of polysulfone and/or polyethersulfone is less than 15% by weight, the heat-resistant dimensional stability of the obtained fiber decreases, and process passability during heat fusion molding decreases. Alternatively, it becomes a factor that reduces thermal dimensional stability when made into a knitted fabric. Specifically, it is necessary that the fresh water shrinkage rate is 25% or less, and if it is less than this value, the desired sheet-like molded product can be obtained by using the above-mentioned binder fiber and changing the composition ratio. Is possible. It can also be said that it is practically sufficient when used as a knitted fabric.

If the content of polyvinyl chloride is less than 20% by weight, the strength of the obtained fibers will not be sufficient (it will be difficult to put it to practical use in obtaining sheet-like molded products).

Polymerization degree of polyvinyl chloride used for PSv fiber (JI
S-6721) is 800-2500, preferably 900-1800.

If the degree of polymerization is less than 800, the fiber strength will be less than 1.2 g/d, which is insufficient for producing a sheet-like molded product, and if the degree of polymerization exceeds 2,500, gelation of the spinning dope is likely to occur, making it unstable. It becomes difficult to manufacture fibers.

Compositional components other than polysulfone and/or polyethersulfone and polyvinyl chloride of PSv fibers include excellent alkali resistance and spinning solvents such as dimethylacetamide, dimethylformamide, and dimethylsulfochloride. selected from polymers that are soluble in acetone or acetone.

These polymers include acrylic resins such as polymethyl methacrylate, polystyrene, ABS resins, styrene/acrylic acid ester copolymers, etc., but acrylic resins such as polymethyl methacrylate are the most suitable for fiber shaping. preferable. Furthermore, it is preferred that the content of these polymers does not exceed 65% by weight.

In order to maintain the alkali resistance of the sheet-like molded product of the present invention, it is necessary that the PSV fibers also have alkali resistance. Specifically, the PSV fibers must be immersed in the above-mentioned KOH 30% aqueous solution and boiled at normal pressure. The fiber weight loss after leaving for 1 hour is 2.
It is 0% by weight or less, preferably 1.5% by weight or less.

Furthermore, in order to improve the liquid retention property of the sheet-like molded product of the present invention, P
Regarding the liquid retention property of the Sv fiber, it is important that the liquid retention rate as measured by the measurement method shown below is 25% by weight or more. This P
The liquid retention properties of Sv fibers are mainly provided by voids in the fibers obtained by wet spinning, and this is effective in increasing the liquid retention properties of sheet-like molded products.

Method for Measuring Liquid Retentivity of Fibers After soaking fibers in water for 24 hours, they are dehydrated using a centrifugal dehydrator for 10 minutes using weighted LOG, and the fiber weight (W) is measured. The dry weight (W2) of this fiber is measured, and the liquid retention rate is calculated using the following formula.

The cross-sectional shape of the PSv fiber is not particularly limited,
Various selections can be made as long as they do not impair alkali resistance, liquid retention, and fiber properties. In order to improve the liquid retention of the C-shaped molded product of the present invention, it is effective to change the cross section of the fibers to an irregularly shaped cross section such as a figure 7 or a cross to increase the voids between the fibers.

In addition, the fineness of the PSV fiber is preferably a fine denier in order to reduce the thickness of the sheet-like molded product, preferably 3 deniers or less, more preferably 2 deniers or less, but it depends on the use of the sheet-like molded product. selected in a timely manner.

PSV fibers are preferably produced by a wet spinning method, and dimethylacetamide and dimethylformamide are advantageously used as solvents in wet spinning, but dimethyl sulfoxide and acetone can also be used.

A spinning stock solution is prepared by mixing and dispersing polysulfone and/or polyethersulfone, polyvinyl chloride, and other appropriate polymers in these solvents. 50℃ of spinning dope
The viscosity of the stock solution is preferably 100 to 2000 poise, preferably 150 to 1000 poise, and the solid content concentration of the stock solution is adjusted to these values. It is preferably less than % by weight.

In addition to these polymers, it is also possible to add a small amount of a heat stabilizer or the like.

The obtained spinning dope is extruded from a spinneret into a coagulation bath and shaped into fibers. The size of the spinneret is appropriately selected depending on the target fineness of the fiber. As the coagulant in the coagulation bath, water, alcohol, etc., which are non-solvents of the polymer, are used, but water is most preferred from an industrial standpoint. The ratio and temperature of the coagulant and solvent in the coagulation bath can be set as appropriate depending on the polymer composition. The undrawn yarn that has left the coagulation bath is washed, stretched, imparted with mechanical properties, collected dry or undried, and used as a raw material for the sheet-like molded product of the present invention.

Various methods can be selected as the manufacturing method for the sheet-like molded product, but wet papermaking is preferred from the characteristics of PSv fibers and the manufacturing method. In the wet papermaking method, a sheet-like molded product can be obtained by cutting the fibers to an appropriate length without drying them, dispersing them in water with binder fibers, and making paper, which requires a drying process during the fiber manufacturing process. This is because energy costs can be reduced without causing damage, and a uniform sheet-like molded product can be obtained. The cut length of the PSv fibers is usually a length that is applied when wet-processing synthetic fibers.

Furthermore, it is also possible to dry the PSv fibers and wind them up into filaments to obtain a sheet-like molded product as a knitted fabric.

<Example> The present invention will be explained below using examples.

Example 1 Using dimethylacetamide as a solvent, the degree of polymerization was 110.
0 polyvinyl chloride (hereinafter referred to as PvC) and a polymerization degree of 98
0 polymethyl methacrylate (hereinafter referred to as P-A),
Polysulfone (hereinafter referred to as PSF) 30150/20
The mixture was dissolved and dispersed in a solvent at a mixing ratio (wt%) to obtain a spinning stock solution. At this time, the solid content concentration has a viscosity of 20 at 50°C.
It was adjusted to be around 0 poise. This spinning stock solution was mixed with 60% by weight of dimethylacetamide and 40% by weight of deionized water.
The mixture was discharged into a coagulation bath at a temperature of 30° C. to obtain an undrawn yarn. This undrawn yarn was stretched approximately 3 times in boiling water, and then washed in boiling water, resulting in a fineness of 0.93 denier and a strength of 1.29.
g/d, fiber with elongation of 33.1% (hereinafter referred to as psv fiber No.
1) was obtained. The weight loss rate of this fiber after KOI+ treatment is 0.93% by weight, the liquid retention rate is 45.0%, and the water conduction shrinkage rate is 18. .

%Met.

The fibers are collected without drying, and 6an is collected in a wet state.
Vinyl chloride/vinyl acetate copolymer fiber (2 denier, cut length 6 body, hereinafter referred to as VA woven fiber) with a heat fusing temperature of 110°C was used as a binder fiber and the mixing ratio (wt%) shown in Table 1. The paper was wet-paper-formed at 115° C. and then heat-fused and molded at 115° C. to obtain sheet-like molded products (sheet Nos. 1 to 5) shown in Table 1 having a basis weight of 50 g/rrr.

Table 1 Example 2 PSV fiber N produced in the same manner as in Example 1.

1, polypropylene fiber (fineness 1.3 denier, cut length 6 mm) and VA woven fiber at the mixing ratio (wt%) shown in Table 2.
g/n? Sheet-like molded products (sheets) shown in Table 2 No.
, 2-9) were obtained.

Example 3 PSV fiber No. manufactured by the same method as Example 1.

1 and VA woven fibers in a mixing ratio (M amount%) of 80/20, and was heat-fused and molded at the heat-fusion temperature shown in Table 3 to obtain a fabric weight of 50.
Sheet-like molded products shown in Table 3 of g/rrr (sheet No.
, 10-13) were obtained.

Table 3 Example 4 PSV fiber N produced in the same manner as in Example 1.

1 and a polyethylene synthetic pulp having a heat fusing temperature of 120° C. instead of VA woven fiber was mixed in an 80/20 ratio. The solid content concentration at this time was adjusted so that the viscosity at 50°C was around 200 poise.

This spinning stock solution was discharged into a coagulation bath containing 70% by weight of dimethylacetamide and 30% by weight of deionized water at a temperature of 30°C to obtain an undrawn yarn. This undrawn yarn was drawn approximately 4 times in warm water at 70°C, and then washed in water to produce fibers (PS).
V fibers No. 2 to 5) were obtained. The performance of the obtained fibers is shown in Table 4.

A sheet-like molded product with a basis weight of 50 g/r4 was made by wet paper making according to Table 4 (wt%) and heat-sealed at 125°C (Sheet No. I 4
) was obtained. The liquid retention rate of this sheet 4Je molded product is 323
%, the strength was also suitable for practical use.

Comparative example 1 PSV fibers w and N produced in the same manner as in Example 1.

In place of 1 and VA woven fibers, polyethylene synthetic pulp with a heat fusing temperature of 132°C was wet-paper-made at a mixing ratio of 80/20, and 1
A sheet-like molded product with a basis weight of 50 g/rrr was obtained by heat-fusion molding at 35°C. Although the strength of this sheet-like molded product was sufficient, the liquid retention rate was at a low level of 130%.

In addition, an attempt was made to make a mixed paper with the same composition and heat-fusion mold it at 115°C, but the fibers did not fuse and a sheet-like molded product with sufficient strength could not be obtained.

Example 5 Using dimethylacetamide as a solvent, the degree of polymerization was 110.
PVC of 0 and PSF were dissolved and dispersed in a solvent at the composition ratio (wt%) shown in Table 4, and the spinning stock solution was prepared using Example 6 PVC/polyethersulfone composition ratio (wt%) of 70.
/30 in the same manner as in Example 5, with a fineness of 1.01 denier, a strength of 2.1 g/d, an elongation of 24%, and a spring shrinkage rate of 18.
．． A 2% fiber (PSV fiber N06) was obtained. When the weight loss rate and liquid retention rate of this fiber after KOH treatment were measured,
They were 1.4% by weight and 61%, respectively.

Example 7 Using dimethylacetamide as a solvent, the degree of polymerization was 110.
0(7)PVC, PMMA, and PSI' were dissolved and dispersed in a solvent at the composition ratios (wt%) shown in Table 5 to obtain a spinning dope. At this time, the solid content concentration has a viscosity of 200 at 50°C.
It was adjusted so that it was near Boise.

This spinning stock solution was discharged into a coagulation bath containing 60% by weight of dimethylacetamide and 40% by weight of deionized water at a temperature of 30°C.
An undrawn yarn was obtained. This undrawn yarn was drawn approximately 3 times in flowing water and further washed in flowing water to obtain fibers (PSV fibers No. 7 to 9) having a denier of 1.0. The performance of the obtained fibers is shown in Table 5.

Example 8 Using dimethylacetamide as a solvent, PvC/PM
The polymer composition ratio (wt%) of MA/PSF was 30150.
Example 7
Spinning and fiber shaping were performed using the same method as in .

Table 6 shows the performance of the obtained fibers (PSV fibers No. 10 to 12).

Table 6 Example 9 Using dimethylacetamide as a solvent, degree of polymerization 110
0 pvc and polystyrene and PSF 50/30/20
A spinning stock solution was obtained by dissolving and dispersing at a composition ratio (wt%) of .

At this time, the solid content concentration was 8 times so that the viscosity at 50° C. was around 200 voids.

This spinning stock solution was processed using the same method as in Example 7 to obtain a fineness of 1.03.
A fiber (PSV fiber No. 13) having a denier, a strength of 1.22, an elongation of 27.8%, and a spring shrinkage rate of 21.5% was obtained. When the weight loss rate and liquid retention rate of the obtained fibers were measured after Ni-011 treatment, they were 1.09% by weight and 71.2% by weight, respectively.
%Met.

Example 10 The PSV fibers obtained in Example 5.6.7.9 were collected without drying, cut into 6 mm pieces in a wet state, and
Wet paper is made with a mixing ratio (wt%) of VA woven fibers of 80/20, and is heat-fused and molded at 115°C to give a fabric weight of 50 g/r+ (7th paper).
Sheet-like molded products (sheet Nos. 15 to 21) shown in the table were obtained.

Comparative Example 2 Using the PSV fiber No. 4 obtained in Example 5, an attempt was made to manufacture a sheet-like molded product in the same manner as in Example 10. Although it was possible to mold using the wet method, the paper shrunk during heat-sealing, making manufacturing difficult.

Comparative Example 3 Using the PSV fibers No. 5 and No. 7 obtained in Examples 5 and 7, an attempt was made to produce a sheet-like molded product in the same manner as in Example 10. The obtained sheet-like molded product had sufficient alkali resistance and liquid retention properties, but its strength was low and it could not be put to practical use.

Example 11 When Sea 1-No. 2 obtained in Example 1 was subjected to hydrophilic treatment with a surfactant, the liquid retention rate was improved to 465%.

<Effects of the Invention> Since the sheet-like molded product of the present invention has excellent alkali resistance, it can be used as industrial filters such as filters for waste alkali treatment, and because it has high liquid retention properties, it can be used in silver oxide batteries, mercury batteries, air batteries, It is extremely useful as a separator for batteries such as alkaline-manganese batteries, nickel-zinc batteries, nickel-cadmium batteries, and alkaline storage batteries.

Patent applicant: Mitsubishi Rayon Co., Ltd.

Claims (2)

[Claims] (1) A sheet-like molded product with excellent alkali resistance, consisting of 50% by weight or more of fibers made of a composition containing at least 15% by weight of polysulfone and/or polyethersulfone and at least 20% by weight of polyvinyl chloride. (2) Fibers composed of a composition containing at least 15% by weight of polysulfone and/or polyethersulfone and at least 20% by weight of polyvinyl chloride.
A sheet-like molded product having excellent alkali resistance, comprising 90% by weight of binder fibers and 50 to 10% by weight of binder fibers having a heat fusion temperature of 125°C or less.