Background Art As well known to those skilled in the art, examples of conventional cushion mattresses include a mattress having a sponge as a cushion material, a mattress using a gel cushion body laminated on a sponge cushion body, and a mattress having a gel elastic body as a cushion material. In the case of the mattress using the gel cushion body laminated on the sponge cushion body, the sponge is used as a cushion material in combination with the gel, but this combination does not sufficiently exhibit a combined visco-elastic property of the gel and sponge.

Disclosure of the Invention Therefore, it is an object of the present invention to provide a double cushion mattress, in which two cushion materials are laminated to show combined elastic properties of the two cushion materials.

It is another object of the present invention to provide a double cushion mattress, in which an upper, a middle, and a lower sheet are laminated by Heat welding High frequency, and Vibration, and glued to align upper and lower cells of the mattress to each other in a vertical direction.

It is still another object of the present invention to provide a double cushion mattress, in which upper gel cushion cells are vertically aligned with lower air cushion cells.

It is yet another object of the present invention to provide a double cushion mattress using PU (polyurethane) gel having visco-elastic properties as a filling material.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of a mattress according to a first embodiment of the present invention; Fig. 2 is a plan view of the mattress according to the first embodiment of the present invention; Fig. 3 is a plan view of a mattress according to a second embodiment of the present invention; Fig. 4 is a partially enlarged front view, partly broken away to show interior construction, of a mattress of the present invention; Fig. 5 is an enlarged view of the portion"A"of Fig. 4; Fig. 6 is an enlarged view of the portion"B"of Fig. 4; Fig. 7 is a partially enlarged view of a mattress according to the present invention; Fig. 8 is a picture of the mattress according to the first embodiment of the present invention; Fig. 9 is a front view of Fig. 8 ; and Fig. 10 is a partially enlarged plan view of Fig. 8.

Best Mode for Carrying Out the Invention A double cushion mattress suggested by the present invention is configured such that cells constituting the double cushion mattress are arranged in a matrix array of upper cells and lower cells, and the upper cells are positioned to

correspond vertically to the positions of the lower cells. In other words, the upper cells and lower cells are filled respectively with filling materials comprising elastic bodies as a cushion material, and the upper and lower cells are positioned to be vertically aligned with each other to exhibit combined elastic properties of the two elastic bodies. For example, an air cushion cell in which compressed air is filled in a closed tube has high elasticity without a pleasant feeling to the touch. On the other hand, a gel cushion cell produced by filling gel in a closed tube and conducting a crosslink-reaction of the gel has elasticity similar to that of human skin, in other words, gel in the gel cushion cell is dispersed when the gel cushion cell is compressed, and then slowly recovered to its original form. Accordingly, the present invention provides a mattress in which cushion materials with different elastic properties are filled in vertically corresponding cells.

In this specification, a cushion mattress is defined as a mattress including a cushion, a cushiony underlay larger than the cushion, a mattress for sleeping, or a cushion sheet for leaning a portion of the human body against.

Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

According to the present invention, provided is a double cushion mattress comprising a mattress tube 10 comprising an upper sheet 11, a middle sheet 12, and a lower sheet 13. The upper sheet 11 and middle sheet 12 are bonded together to form a lattice of upper cells 14 therebetween, and the lower sheet 13 is bonded to the middle sheet 12 to form a lattice of lower cells 15 therebetween. In such a case, the upper cells 14 are spaced apart from each other at regular intervals, and, in the same manner, the lower cells 15 are spaced apart from each other at the same regular intervals, so that the upper and lower cells 14 and 15 vertically correspond in position to each other. The cells 14 and 15 constituting the double cushion mattress are thus exactly aligned with each other in a vertical direction to form a matrix array. At this time, each upper cell 14 is positioned to vertically correspond to an associated lower cell 15. The double cushion mattress also includes a first cushion material 16 filled in the upper cells 14, and a second

cushion material 17 filled in the lower cells 15.

Each upper cell 14 comprises a space positioned between the upper sheet 11 and the middle sheet 12, and each lower cell 15 comprises a space positioned between the middle sheet 12 and the lower sheet 13.

The upper, middle, and lower sheet 11, 12, and 13 constituting the mattress tube 10 of the present invention are all made of a plastic film which can realize a mechanical bonding such as a high frequency bonding, a heat fusion, and a vibration bonding, or a chemical bonding with the use of an adhesive.

The upper sheet 11 ranging from 0.05 to 1 mm in thickness is selected from the group consisting of thermoplastic resin such as PE (Polyethylene), PVC (Polyvinyl chloride), TPU (Thermoplastic Urethane), TPS (Thermoplastic styrene), and PP (Polypropylene), and thermosetting film such as PU (Polyurethane), and preferably consists of TPU with excellent softness and texture.

The middle sheet 12 is 0.05 to 1.5 mm in thickness, and is selected from the thermoplastic resin group consisting of PVC, PP, and PE. Preferably, low- priced PE film with excellent mechanical strength and workability is useful as the middle sheet 12.

In addition, the lower sheet 13 is 0.1 to 2 mm in thickness, and selected from the thermoplastic resin film group consisting of PVC, PP, PE, TPE, TPU, TPS, and PC (Polycarbonate). Preferably, PVC or Polyvinylidene chloride film having excellent airtightness, mechanical strength, and heat-adhesive properties is used as the lower sheet 13.

The mattress of the present invention comprises the first cushion material 16 and the second cushion material 17 vertically corresponding to each other, thus showing combined elastic properties of two cushion materials. Examples of cushion materials useful to construct the mattress of the present invention include compressed air, water, and gel. Preferably, air and gel are used as the cushion material in the present invention. Examples of combination of cushion materials using air and gel filled in mattress cells are given in Table 1, below.

TABLE 1 Combinations of cushion materials filled in the upper and lower mattress cells Combination Upper cell Lower cell 1 Gel Gel 2 Gel Air 3 Air Gel 4 Air Air

As described in Table 1, in combination examples 1 and 4, the same cushion materials are used in one mattress. On the other hand, different cushion materials, that is to say, gel and air are used in one mattress in the case of examples 2 and 3. Most useful in the combination of cushion materials according to the present invention is combination example 2. As described above, in the case of combination example 2, gel is filled in the upper cells 14 and air is filled in the lower cells 15.

Gel useful in the mattress cells (upper cells or lower cells) may consist of silicone gel or PU gel. Materials for forming gel are mixed prior to being filled in the mattress cells, and crosslinked after being filled in the mattress cells, to allow the gel cushion cells to act as mattress cells having soft gel visco-elasticity.

Meanwhile, after air is filled in the mattress cells, the mattress acts as an air cushion mattress with sensitive elastic properties. When air is filled in the cells, an air pump is used as an air supplying means. Preferably, a manual pump or a motorized air pump driven by a DC motor is used as the air pump. When air is filled in the lower cells 15 while gel is filled in the upper cells 14, pressure in the upper cells 14 is increased. Accordingly, pressure in the upper gel cushion cells 14 is partially controlled by air pressure in the corresponding lower cells.

Generally, air is filled in the mattress cells just before the mattress is used. At this time, a user may control pressure in the mattress cells while monitoring elasticity of the mattress. Preferably, pressure in the air cushion cells is 0.02 to 1. 5 kg/cm2.

The upper cells 14 comprise an upper edge junction part 22, consisting of the upper sheet 11 and the middle sheet 12, surrounding all upper cells 14 so as to uniformly fill the first cushion material through a first port 21 into all upper cells

14. An upper partition junction part 23 fixes boundaries of the upper cells 14, and an upper communicating channel 24 allows the upper cells 14 to communicate with each other. Likewise, the lower cells 15 comprise a lower edge junction part 32, consisting of the middle sheet 12 and the lower sheet 13, surrounding all lower cells 15 so as to uniformly fill the second cushion material through a second port 31 to all lower cells 15. A lower partition junction part 33 fixes boundaries of lower cells 15, and a lower communicating channel 34 allows the lower cells 15 to communicate with each other. Sizes and shapes of the upper and lower cells 14 and 15 depend on intervals between the upper and lower partition junction parts 23 and 33 and patterns of the partition junction parts 23 and 33. Each of the cells 14 and 15 may have elongated, circular, and polygonal shapes. Ports 21 and 31 are provided with check valves 25 and 35 to prevent the liquid cushion material from undesirably leaking through the ports 21 and 31 from the cells 14 and 15. In the case of producing the mattress tube 10 according to the high frequency induction process, the edge junction parts 22 and 32 and the partition junction parts 23 and 33 are simultaneously formed.

Prior to the process of producing the double cushion mattress of the invention, the upper and lower sheets 11 and 13 may be fabricated with cells previously formed in a raised form like the resulting upper and lower cells having the cushion materials.

A reference character C shown in Fig. 7 denotes a protective film for protecting the mattress during transport, which is removed before being used by a user.

Useful as gel filled in the mattress cells is silicon gel or PU gel, and preferably light PU gel with low price and excellent elasticity.

According to the present invention, materials for forming PU gel are classified into two types of liquid materials. In detail, a PU gel elastic body is produced by filling a mixture of prepolymer with miscellaneous components in the upper cells and maintaining the temperature of the resulting mixture at 80 °C for 30 min.

In addition, PPG 3000 diol is reacted with H-MDI in a stoichiometric ratio

of 1: 1 in the presence of Tin catalyst (0.00077 parts by weight) at 80 °C for 4 hours to produce the prepolymer. The stoichiometric ratio of reactants is described in Table 2, below.

TABLE 2 Stoichiometric ratio of reactants used to produce the prepolymer PPG 3000 diol 1 equivalent H-MDI 1000 1 equivalent

24 to 45 parts by weight of the prepolymer is subjected to a crosslinking reaction in conjunction with 70 to 90 parts by weight of MW 4000 diol, 10 to 30 parts by weight of MW 3000 diol, a proper quantity of plasticizer such as DOP, DINP, DOS, DBP, and polyesters, a proper quantity of DBTDL, and a proper quantity of Tin catalyst at 80 °C for 30 min to produce a PU gel elastic body.

A preferable stoichiometric ratio of reactants used to produce the PU gel elastic body is given in Table 3, below.

TABLE 3 Stoichiometric ratio of reactants used to produce the PU gel elastic body prepolymer 29. 8 parts by weight MW 4000 diol 90 parts by weight MW 3000 diol 10 parts by weight Plasticizer a proper quantity DBTDL a proper quantity Tin catalyst a proper quantity

A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed as the limit of the present invention.

EXAMPLE 1

Materials as described below were filled in the upper cells and then subjected to a crosslinking reaction to produce a PU gel elastic body.

Material Mixing ratio MW 4000 diol 90 parts by weight MW 3000 diol 10 parts by weight DOP 30 parts by weight DBTDL 0.2 parts by weight T-9 0. 085 parts by weight Toner yellow 1 parts by weight Prepolymer 29.8 parts by weight The PU gel elastic body thus produced was tested in terms of elasticity.

The results are described as follows.

Test of penetration 225 (KS-M 2095, JIS K 2207) Test of compression strength 0.158Kgf (KS-M6518) EXAMPLE 2 Materials as described below were filled in the upper cells and then subjected to a crosslinking reaction to produce a PU gel elastic body.

Material Mixing ratio MW 4000 diol 90 parts by weight MW 3000 diol 10 parts by weight DOP 25 parts by weight DBTDL 0.2 parts by weight T-9 0.09 parts by weight Toner red 1 parts by weight Prepolymer 29.8 parts by weight

The PU gel elastic body thus produced was tested in terms of elasticity.

The results are described as follows.

Test of penetration 190 (KS-M 2095, JIS K 2207) Test of compression strength 0.570 Kgf (KS-M6518) EXAMPLE 3 Materials as described below were filled in the upper cells and then subjected to a crosslinking reaction to produce a PU gel elastic body., Material Mixing ratio MW 4000 diol 90 parts by weight MW 3000 diol 10 parts by weight DOP 20 parts by weight DBTDL 0.2 parts by weight T-9 0.09 parts by weight Toner green 1 parts by weight Prepolymer 31 parts by weight The PU gel elastic body thus produced was tested in terms of elasticity.

The results are described as follows.

Test of penetration 130 (KS-M 2095, JIS K 2207) Test of compression strength 0. 85 Kgf (KS-M6518) EXAMPLE 4 Materials as described below were filled in the upper cells and then subjected to a crosslinlcing reaction to produce a PU gel elastic body.

Material Mixing ratio MW 4000 diol 90 parts by weight MW 3000 diol 10 parts by weight DOP 15 parts by weight DBTDL 0.22 parts by weight T-9 0.09 parts by weight Toner blue 1 parts by weight Prepolymer 31 parts by weight The PU gel elastic body thus produced was tested in terms of elasticity.

The results are described as follows.

Test of penetration 95 (KS-M 2095, JIS K 2207) Test of compression strength 0.95 Kgf (KS-M6518) In examples 1 to 4, the gel elastic body was subjected to a crosslinking reaction to form a shape of cell.

In detail, components of the PU gel elastic body were subjected to a crosslinking reaction after being filled in the mattress upper cells, and compressed air was filled in the lower cells to produce a double cushion mattress having combined elasticity of gel and air. The double cushion mattress of the present invention in which PU gel is filled in the upper cells and compressed air is filled in the lower cells has advantages of price lower and weight lighter than a mattress having upper and lower cells all being filled with gel.

Industrial Applicability As described above, the present invention provides a double cushion mattress, in which two cushion materials are filled in upper and lower cells which are spaced apart from each other at regular intervals such that the upper and lower

cells are exactly aligned with each other in a vertical direction to form a matrix array. The double cushion mattress thus shows an elastic property combining elastic properties of the two cushion materials. In order to produce the double cushion mattress, an upper, a middle, and a lower sheet are laminated and glued to allow the upper and lower cells to vertically correspond in their positions, such that the upper gel cushion cells are vertically aligned with the lower air cushion cells, with PU gel used as a gel elastic body.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.