JPH02190126A - Absorbing sheet for pet animal - Google Patents

Abstract

PURPOSE:To form absorbing sheet for pet animal having excellent liquid- absorbing speed, liquid-absorbing ability and wet strength by applying water- repelling treatment or joining with liquid-impermeable film to one face of sheet comprising compressed cellulosic sponge material containing reinforcing fiber. CONSTITUTION:One face of a sheet composed of compressed cellulosic sponge material containing reinforcing fiber is subjected to water-repelling treatment or joined with liquid-impermeable film to form the subject sheet. Water- absorbing and swelling polymer is preferably contained in the compressed cellulosic sponge material. For instance, natural fiber such as ramie, cotton or pulp or various chemical fiber (e.g. rayon yarn or polypropylene yarn) is utilized as reinforcing fiber. As water-repellent, conventional silicone-based or fluororesin-based agent is shown and film of polyethylene, polypropylene, polyester or polyvinyl chloride, etc., is utilized as liquid-impermeable film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an absorbent sheet for pet animals that has excellent liquid absorption ability and shape retention (strength) when wet.

(Prior art and its problems) For absorbing and processing the urine of pet animals such as dogs and cats.

An absorbent sheet is used. Conventional absorbent sheets are mainly made of absorbent paper and contain water-absorbing and swelling polymers.

However, such absorbent sheets have low wet strength, so when a pet animal moves on it after urinating,
The absorbent sheet may be cut, torn, or twisted into clumps, resulting in problems such as urine leaking from the absorbent sheet.

Such problems can be solved to some extent by using absorbent paper with high wet strength as the absorbent paper. However, when the wet strength of the absorbent paper is increased, the liquid absorption speed and liquid absorption capacity deteriorate, resulting in the inconvenience that it becomes impossible to effectively treat the urine of pet animals.

(Problem of the Invention) An object of the present invention is to provide an absorbent sheet for pet animals that is excellent in liquid absorption speed and ability, and also has excellent wet strength.

(Means for Solving the Problems) The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, they have completed the present invention.

That is, according to the present invention, there is provided an absorbent sheet for pet animals, which is formed by subjecting one side of a sheet made of a compressed cellulose sponge to a water-repellent treatment or bonding a liquid-impermeable film to the sheet.

The cellulose sponge used in the present invention means a sponge having a cellulose skeleton. Examples of such materials include sponges made of cellulose itself, sponges made of cellulose derivatives such as viscose, cellulose ether, cellulose ester, etc., and sponges made of mixtures thereof. Also,
The cellulosic sponge can include reinforcing fibers, for example. This cellulose sponge is usually 1,0
．． 01-0.8g/aJ, preferably 0.03-0.6
g/a+? It has a low density.

Next, an example of manufacturing a cellulose sponge using viscose as a raw material is a mixture obtained by adding reinforcing fibers and other auxiliary ingredients to viscose, and adding and mixing commonly used crystalline sulfate. After molding into a desired shape and coagulating it by heating, it is brought into contact with an acidic aqueous solution to regenerate cellulose, and then washed with water and dried to obtain a sponge.

The cellulose concentration in the raw material viscose is not particularly limited, but it is usually preferably set to 8 to 10% by weight.The alkali concentration in the viscose is 3 to 15% by weight, preferably 5 to 10% by weight. The amount of reinforcing fibers added to the viscose which may be defined is generally such that its proportion in the sponge is 10-50% by weight. That is, it is 10 to 50% by weight based on the total amount of cellulose and reinforcing fibers in the viscose.

Examples of reinforcing fibers include natural fibers such as ramie hemp, cotton, and pulp, as well as various synthetic fibers such as rayon, polypropylene, and polyester fibers. These materials may be used alone or in the form of a mixture of two or more. The crimp rate (JIS
It is preferable to use synthetic fibers with L 1015 (7,12°2)) in the range of 10 to 30% by weight or synthetic fibers with irregular cross sections (cross sections of shapes other than circles or ellipses).The length of the reinforcing fibers is The range is 5-20mm and the fiber thickness is 0.5-20mm.
It is preferable to define the denier to be 15 d (denier), preferably in the range of 1 to 6 d.

Generally, crystalline Glauber's salt having an average particle size of 1 to 5III is used, and the amount added is 20 to 80 times the total amount of cellulose and reinforcing fibers in the viscose. The crystalline mirabilite added to viscose is eluted and removed from the sponge during the coagulation, regeneration process, and water washing process.

Various additives can be added to the raw material viscose in order to improve the physical properties of the resulting sponge. As such additives, various surfactants can be added as dispersants in order to promote dispersion of reinforcing fibers and penetration of viscose into reinforcing fibers. In addition, to improve the performance and flexibility of the sponge, polyol compounds, chemically modified cellulose, urea, etc. can be added as modifiers.The amount of surfactant used as a dispersant is A range of .1 to 2 weight 2 is preferred. The amount of the modifier such as a polyol compound is preferably in the range of 1 to 10% by weight based on viscose.

Examples of the surfactant include water-soluble anionic surfactants such as sodium α-olefin sulfonate having 14 carbon atoms, sodium lauryl sulfate, and sodium polyoxyethylene lauryl ether sulfate (3 moles of ethylene oxide added); , Tween 8Q,
Jetanolamide with 12 carbon atoms, polyoxyethylene lauryl ether (8 moles of ethylene oxide added)
Examples include nonionic surfactants of HLBIO or higher.

Examples of the polyol compound include glycerin and polyalkylene gelylcols such as polyethylene glycol and polypropylene glycol. The average molecular weight of the polyol compound ranges from 90 to too much, preferably from 600 to 6,000.

Furthermore, in order to improve the strength of the sponge, an unsaturated carboxylic acid ester represented by the following general formula is used as at least one monomer component, and the glass transition temperature obtained is in the range of -15 to 20°C. Aqueous emulsions of polymers can be added.

CHR”=CH” C0OR' In the above formula, R1 and R2 represent hydrogen or a methyl group.

R3 represents an alkyl group, particularly preferably a lower alkyl group having 2 to 5 carbon atoms.

Specific examples of the unsaturated carboxylic acid ester include ethyl acrylic acid and methacrylic acid.

Examples include propyl or butyl esters.

Among the above polymers, if a polymer with a glass transition temperature lower than 115°C is used, the resulting viscose sponge will become sticky, which is undesirable.On the other hand, if it exceeds 20°C, the flexibility of the resulting viscose sponge will decrease. The glass transition humidity, which is undesirable because properties become impaired, is the temperature at which a polymer changes from a glassy, hard state to a rubbery state, and is influenced by structural factors of the polymer.

Generally, the glass transition temperature is higher for polymers having a crosslinked structure, and changes depending on the degree of crosslinking. Also.

It decreases when plasticizers are added to the polymer. Therefore.

The glass transition temperature of a polymer can be controlled by adjusting the degree of crosslinking of the polymer, the amount of plasticizer added, and the like.

The aqueous emulsion of the polymer can be obtained by emulsion polymerization of the unsaturated carboxylic acid ester in an aqueous medium in the presence of an emulsifier. Regarding the production of aqueous emulsions of this polymer, see 1, for example, Japanese Patent Publication No. 62-4588.
This method is described in detail in Publication No. 2 and Japanese Patent Application Laid-open No. 109803/1983. The average particle size of the polymer particles in the aqueous emulsion is usually 0.01 to 5.0. However, as the polymer particles become smaller, the specific surface area increases and the adhesive force improves, so it is preferable that the average particle size is smaller.

In addition, the polymer may be a homopolymer or a copolymer of the monomer represented by the general formula (1) described above, or it may be a copolymer with another unsaturated monomer. Can be done. In this case, unsaturated monomers include vinyl chloride, vinyl acetate, styrene, acrylamide, divinylbenzene, etc., but the content in the polymer is 10 mol% or less, preferably 5 mol% or less. be.

In addition, cellulose sponge has 1 colorant, deodorizer,
Auxiliary ingredients such as antibacterial agents and bactericidal agents can be added.

The heating temperature for coagulating the viscose mixture is 90
Temperatures of ˜100° C. are generally employed and treatment times are on the order of about 2 hours. In this case, in order to shorten the heat treatment time, the viscose mixture may be treated with sulfuric acid or sulfuric acid/zinc sulfate in advance during the heat treatment.

The compressed cellulose sponge used in the present invention is obtained by compressing the low-density sponge obtained as described above, and the density thereof is 0.1 to Ig/ad, preferably 0.3 to 0.
, can be obtained by increasing to 5 g/d. If the density of compressed sponge is less than the above range, the strength will be low, while if it is larger than the above range, the flexibility (hand) will be poor.

It is preferable to compress the material to a density within the above range.

It is preferable that the compressed cellulose sponge contains a water-absorbing and swelling polymer. Examples of water-absorbing swelling polymers include conventionally known ones, such as hydrolysates of acrylonitrile-grafted starch, crosslinked polyacrylates, and polyacrylamide-based polymers.

There are vinyl acetate/methyl acrylate copolymer types. Such water-absorbing and swelling polymers are used in the form of granules, powders, fibers, etc., and the shape is not particularly limited. In addition to the method of interposing it in the form of a sandwich between two sponges, it can also be incorporated into the sponge. Furthermore, the monomer that is the raw material for the water-absorbing and swelling polymer can be impregnated into a sponge, and in this state, a polymerization reaction and a crosslinking reaction can be performed to contain it in the sponge. The amount of water-absorbing swelling polymer used is based on the total amount of the sponge and water-absorbing swelling polymer.

The ratio is 5-70% by weight.

To produce the absorbent sheet of the present invention, one side (back side) of the compressed cellulose sponge sheet is subjected to water repellent treatment or a liquid-impermeable film is bonded to it. As the water repellent, a conventional silicone-based or fluorine-based water repellent is used. Liquid-impermeable films include polyethylene, polypropylene, polyester, polyamide,
Films made of various synthetic resins such as polyvinyl chloride can be used.1 Methods of joining the synthetic resin film to the sheet surface of the compressed sponge body include a method using an adhesive, a method of laminating and bonding molten synthetic resin films, etc. be. Further, a liquid permeable sheet such as a nonwoven fabric or a synthetic resin film having pores can be bonded to the surface of the compressed sponge body. Furthermore, on the outer surface of the liquid-impermeable film bonded to the back surface of the compressed sponge sheet, in order to facilitate immobilization of the sheet during use,
An adhesive layer can also be formed.

(Effect of the invention) The absorbent sheet for pet animals of the present invention, as a liquid absorber,
Since a compressed cellulose sponge is used, it can be used as a very compact product. Therefore, it does not take up much space to store or display, and even though it is a compressed body, it has excellent shape retention. Furthermore, it has excellent liquid absorption properties, and when it absorbs urine, it quickly absorbs it, shows an increase in volume, and has the property of returning to its original volume of an incompressible body. In addition, the compressed sponge material has excellent wet strength, so even if a pet animal steps on it when it absorbs urine, it will not cut or tear, and the urine will stick to the animal's paws. There's not much to do.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Example [Production of sponge] To viscose containing 9% by weight of cellulose and 5% by weight of alkali, ramie hemp with a length of 10 mm was added as a reinforcing fiber at a ratio of 40% by weight of the cellulose in the viscose, and crystallized. Glauber's salt (average particle size: 3+am) was added in an amount 50 times the weight of cellulose in the viscose, then an aqueous emulsion of the polymer was added, mixed, and the mixture was shaped into a block. After boiling at 100° C. for 3 hours, it was immersed in 4% sulfuric acid to regenerate cellulose, washed with water, and dried to obtain a viscose sponge.

The performance of the viscose sponge obtained as described above was evaluated as follows. The results are shown in Table-1.

(1) Flexibility (texture) Dry sponge with thickness 10mm, length 100+sm, width 1
A sensory test was conducted on the pieces cut into square pieces of 00+ mm and evaluated by five women.

0...Very good 0...Good Δ...Fair
Passive
A sample cut to m5+ was used as a sample, and after being immersed in water, the tensile strength was measured using a tensile tester at a chuck interval of 100 mm and a tensile speed of 200 m/min.

Table 1 Note that the aqueous emulsion of the polymer used above was obtained using butyl methacrylate as a monomer. That is, by dissolving an emulsifier and a water-soluble catalyst in water according to a conventional method, adding a monomer and a surfactant while stirring, and heating, various glass transition temperatures shown in Table 1 can be achieved. with a concentration of 40% by weight and an average particle size of 0.
An aqueous emulsion of 174 was obtained.

[Manufacture of absorbent sheet]

The block-shaped sponge of Experiment No. 3 was cut into sheets with a thickness of 3 mm and compressed with a roller to form a compressed sponge body (bulk density 0.45 g/cd). A hot polyethylene film was placed on the back of the compressed sheet. An absorbent sheet was obtained by joining using a melt method.

On the other hand, for comparison, a cotton-like valve seat with a thickness of 3 mm (
(bulk density: 0.1 g/aj) was sandwiched between a nonwoven fabric and a polyethylene film, and the peripheral edges were joined to obtain a comparative absorbent sheet.

Next, each absorbent sheet obtained as described above was subjected to a practical test and evaluated as follows. The results are shown in Table-2.

(1) Occurrence of twisting and cracking.Used in 5 households that keep Yorkshire terriers.
The absorbent sheet after use was evaluated based on the overall average score based on a sensory test. The evaluation criteria were as follows, and the average score of the five households was used as the evaluation score.

There is a lot of twisting and sharpness... There is some twisting and sharpness at one point... There is no twisting and sharpness at three points...
・5 points (2) Footprints after a dog steps on a sheet that has absorbed urine.

When walking on wooden floors and tatami mats, whether or not footprints were left due to urine was evaluated based on the overall average score.

The evaluation criteria were as follows, and the average score of the five households was used as the evaluation score.

There are a lot of footprints... There are a few 1-point footprints... There are no 3-point footprints...
- 5-Point Table-2 Example 2 A sponge was produced in the same manner as in Example 1 except that no aqueous emulsion was added to the viscose.

The obtained sponge was cut into sheets with a thickness of 3 mm and rolled to form compressed sponge bodies (bulk density 0.45 g/cd).
I got it. A polyethylene film was bonded to the back surface of this compressed sheet using a hot melt method to obtain an absorbent sheet. When this absorbent sheet was subjected to a practical test, similar good results as in Example 1 were obtained.

Example 3 On the back side of the compressed sheet obtained in Example 2, a coating liquid made of silicone resin, fluororesin, metal soap, etc. was applied as a water repellent and dried to obtain an absorbent sheet. It was confirmed that this absorbent sheet prevents urine absorbed from the front surface from leaking from the back surface.

Example 4 Water-absorbing and swelling polymer particles were dispersed on the surface of the absorbent sheet obtained in Example 2, a nonwoven fabric was layered thereon, and the periphery was adhered to obtain an absorbent sheet containing the water-absorbing and swelling polymer. This absorbent sheet had significantly improved urine absorption ability due to the action of the water-absorbing and swelling polymer.

Claims (2)

[Claims] (1) An absorbent sheet for pet animals, which is made of a sheet made of a compressed cellulose sponge containing reinforcing fibers, and one side of which is treated with water repellent treatment or bonded with a liquid-impermeable film. (2) The sheet according to claim 1, wherein the compressed body contains a water-absorbing and swelling polymer.