JPH0555633B2 - - Google Patents

Abstract

Process particularly suitable for sheet material of the type comprising a porous polyurethane resin matrix, the latter containing polyester or polyethylene fibres, and a pressed polyurethane resin cover film patterned to imitate real leather; the said process consisting in treating the said material, inside rotary tanning drums, with a trivalent metal salt solution which is brought up to precipitation pH level in such a manner as to fill the pores in the said polyurethane matrix on the said sheet material with a corresponding hydroxide, after which, the material is treated with a dialdehyde, fireproofing, colouring and softening substances.

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention uses as a raw material one of the many synthetic sheet materials known and commercially available under various trade names and commonly referred to as "imitation leather," which is similar to genuine tanned leather. This invention relates to a method of producing artificial leather having a similar appearance and feel. This invention relates to a chemical treatment particularly suitable for synthetic sheet materials comprising porous polyurethane resin matrices. BACKGROUND OF THE INVENTION Various synthetic sheet materials made from polymer resins are known that are designed to resemble and replace various types of genuine leather for a wide range of applications, including, for example, upholstery, shoes, and clothing. These synthetic sheet materials are typically made using two layers of polyurethane resin laminated together, with the bottom layer being a porous matrix (due to the manufacturing process) designed to give stiffness and thickness to the sheet material. The top layer is dense and usually painted and printed with a pattern similar to genuine leather. Of the known materials, the ones most similar to genuine leather in terms of stiffness and appearance are those of the type mentioned above, i.e. polyester or polyurethane fibers formed by a layer of polyurethane resin and free to move along an axis inside the matrix. It consists of a porous, open-cell matrix with embedded pores. A cross-section of this material is shown micrographed in FIG. This material is manufactured and sold by Kuraray Co., Ltd. PROBLEM SOLVED BY THE INVENTION The main drawback of the known materials of the type mentioned above is that they are highly flammable and thus require the addition of fire-retardant substances. Addition of fire-retardant substances not only significantly impairs the appearance, but also makes the material unsuitable for a wide range of applications, such that the appearance, feel, hardness, etc. of the material is inferior to that of genuine leather. becomes. An object of the present invention is to provide a method for producing artificial leather from the above-mentioned type of synthetic sheet material, which has an appearance and hardness almost identical to that of genuine leather, and also has fire retardant properties. Means for Solving the Problems The method for producing artificial leather according to the present invention comprises a layer of porous polyurethane matrix in which polyester and/or polyethylene fibers are embedded, and a layer of porous polyurethane matrix laminated to said matrix layer to resemble genuine leather. pressed polyurethane resin cover film
A method for producing artificial leather similar to genuine leather by chemically processing a type of porous synthetic sheet material consisting of a resin cover film), in which the synthetic sheet material is treatment with an aqueous solution of a metal salt of at least one metal selected from the group so that the aqueous salt solution penetrates substantially the entire synthetic sheet material, and after completion of the salt solution treatment, by adding a strong base. , the PH value of the salt solution is increased to precipitate the corresponding hydroxide of the metal salt in the form of a gel into the pores of the synthetic sheet material, and then the synthetic sheet material is treated with mineral oil and/or It is characterized by applying an oiling treatment consisting of treatment with an emulsion of fatty acid ester. By subjecting porous synthetic sheet materials to a tanning process, which is a process that is very similar to the process of preventing corrosion of genuine leather, the applicant changes the appearance and hardness of the synthetic sheet materials to the point that they closely resemble those of genuine leather. I discovered that. The surprising part about this discovery is that it is well known that tanning has little effect on the appearance or hardness of genuine leather; the purpose of tanning is simply to prevent the leather from corroding; The structure that provides the well-known characteristics remains unchanged. Synthetic sheet materials, known as "imitation leather", are not only naturally non-corrosive but also contain polymer chains with nearly saturated bonds and are therefore susceptible to commonly used tanning agents. I don't receive it. Therefore, tanners and organic chemists in general would consider tanning synthetic sheet materials to be pointless or even completely unreasonable. In experiments conducted by the applicant, porous synthetic sheet materials (i.e., with minute pores visible only with an electron microscope) were first subjected to ``pseudo-sealing''.
treated with a salt solution, i.e. of the type normally used in known tanning processes or of a type with similar physicochemical properties, and then applied to the sheet material with an oil emulsion of the type applied to genuine leather. A greasing process that involves treatment with a slurry solution ensures that the sheet material absorbs and retains at least a portion of the tanning salts contained in the salt solution, resulting in After treatment, the appearance and hardness of the sheet material change significantly. More precisely, the hardness of the sheet material increases, giving it the look and feel characteristic of real tanned leather. Additionally, the process described above reduces the flammability of the sheet material, allows for any dyeing treatment specific to the polymer forming the treated sheet material, and provides a final product that closely resembles genuine leather and has a good appearance. It becomes possible to manufacture products. The applicant has further proposed that the flexibility of the sheet material is brought to almost the same level as that of genuine leather by treatment not only with a pseudo-tanning salt solution and anointing oil, but also with an aqueous solution of at least one dialdehyde or polyaldehyde. I discovered things that could be improved. Also,
Applicants further note that, for best results,
The simulated tanning salt solution treatment differs from the tanning of genuine leather by adding a strong base such as NaOH (sodium hydroxide) in place of the weak base such as sodium bicarbonate used in regular chrome tanning. We discovered that it was necessary to appropriately adjust the pH of the salt solution. The treatment salts are preferably trivalent metal sulfates and/or chlorides and/or divalent metal sulfates (ie, metals such as iron, which can undergo varying degrees of oxidation). In this invention, porous synthetic sheet material (strips typically about 10 meters long) are collected, tied, and charged inside a rotating drum of the type commonly used, for example, in genuine leather tanning operations. You will get a bundle of dimensions. The bundle of synthetic sheet materials thus shaped is placed in a drum, and the sheet materials are chemically treated by supplying various chemical solutions into the drum as the drum rotates. Specifically, in this invention, the porous synthetic sheet material is first subjected to a "soaking" treatment in which it is treated in an aqueous solution of a surfactant at 50°C to 60°C for 10 minutes to 1 hour. Ru. The "infiltration" process completely infiltrates the material, filling virtually all pores in the material with liquid, and in the rotating drum contains a first divalent and/or trivalent metal salt solution. Filled with processing solution. The synthetic sheet material is treated in this salt solution for about 10 minutes to 1 hour, so that substantially the entire sheet material is impregnated with the solution. It is then treated with a pseudo-tanning sodium hydroxide solution to raise the pH value to about 7. At this point, the temperature of the solution rises to about 60°C, and some of the salts contained in the solution in the form of hydroxides are precipitated, increasing the pH value, which exceeds 7.5. Must not be. The hydroxide precipitates in solution in approximately the form of a gel. The longer the treatment of the sheet material in the salt solution of pseudo-tanning, the more fully saturated some of the numerous pores of the sheet material become, so that during the precipitation step some of the hydroxides are in the form of gels. The gel precipitates directly into the pores, filling them with gel, which increases the weight and stiffness of the treated sheet material quite significantly. Furthermore, it is well known that hydroxide is a fairly good fire retardant, so the treated synthetic sheet material is significantly less flammable than its original state. Once the precipitation stage is complete, the sheet material is cleaned and
All traces of hydroxide on the surface are removed. The sheet material is then treated inside a rotating drum with an aqueous solution of dialdehyde or polyaldehyde at a weight ratio of 5 to 10% for 10 minutes to 1 hour. It has been found that treating the sheet material with dialdehyde provides flexibility while also maintaining the excellent properties achieved by the sheet material in normal use. The treated sheet material is also subjected to a series of other treatments, the most important of which is the oiling treatment, in order to achieve the desired result, i.e. convert the raw synthetic material to genuine leather. It was found that this is essential for modifying into almost the same material. The fact that the oiling treatment is performed in a rotating drum is the same as the oiling treatment of genuine leather. However, mineral oil or a fatty acid ester emulsion with a high fatty acid content can be used without discrimination, and it is preferable to insert sulfur and apply at a temperature of about 600°C for several minutes to one hour. composite materials,
In other words, when processing materials in which synthetic fibers are embedded in a porous synthetic matrix, the oil application process removes esters and oils that are not normally retained in dense synthetic resins, and the It is retained in the pores of the treated sheet material, giving the treated sheet material the unique appearance of genuine leather.
In addition, the oils and esters improve fiber flow within the porous matrix, giving the treated sheet material the stiffness and feel unique to genuine leather. In this invention, the subsequent processing of the sheet material includes:
The dyeing process is carried out by known methods, i.e. after washing the sheet material in cold water, and according to the invention, the sheet material is placed in a rotating drum using the usual fire-retardant substances used in the known fire-retardant treatments (with little success). Instead, for several minutes in a fire retardant solution containing flame retardants of the type used to suppress wildfires.
There is a fire prevention treatment that is carried out by treating for one hour. Flame retardant materials are commercially available under various trade names and include ammonium salts. The flame retardant material is, for example, ammonium phosphate. Although the flame retardant material is absorbed into the sheeting material, rendering it non-flammable, the resulting material is hard and completely unusable. However, such hardening is achieved according to the invention by a finishing treatment in which the sheet material is again treated in a rotating drum in a solution of common commercially available softening substances, such as laurates (softening solution), and by fireproofing. ) or flame retardant (fire
retarding) can be overcome in combination with solution treatment. Specifically, according to the invention, the synthetic sheet material is treated in a fire protection solution of PIROFLAM® (ammonium salt);
Then TRIANOLSP® (Laurate)
At this time, a small percentage of ammonium and flame retardant salts absorbed into the sheet material are added to prevent them from decomposing during the fire protection treatment.
Add PIROFLAM. Finally, the sheet material is dried in hot air, then unbundled, and the sheet material is rolled up in exactly the same way as real leather and sent to the finishing process. The finishing step is performed in a well-known manner and is not within the scope of this invention and will not be discussed here. The applicant has proposed a specific group of synthetic sheet materials, namely "imitation leathers", i.e. layers of porous polyurethane matrix in which polyester and/or polyethylene fibers are embedded, and dense pressed leather laminated to said matrix layer. It has been discovered that it is possible to produce high-quality artificial leather almost identical to genuine leather only when the method according to the present invention is applied to a porous synthetic sheet material consisting of a polyurethane resin cover and a film. The dyeing step consists of lubricating the sheet material with a sulfur-saturated ester and then applying a mixture of complex metal coloring substances specifically designed for polyester or polyurethane polymer fibers in a rotating drum. This is done by treating the sheet material for at least 2 hours in a . The dyeing process is carried out in such a way that the colored substance is continuously deposited on the sheet material. The dyeing process is carried out at about 40°C for at least about 1 hour, after which the temperature is increased to about 60°C and the remaining dyeing steps are carried out. The sheet material is then dried in a drum at approximately 70°C by means of forced hot air circulation. The rotational speed of the drum is preferably 4 to 6 rpm. The sheet material used has a thickness of 0.3 to 2 mm depending on the purpose. After being treated in accordance with the present invention, the sheet material preferably looks as shown in the photomicrograph of FIG. 1st and 2nd
The micrographs shown in the figure clearly show the structural differences in the material before (FIG. 1) and after (FIG. 2) treatment according to the invention. Figure 2 shows relatively low quality "imitation leather" according to the invention.
This clearly shows that the material can be converted into very high quality artificial leather for manufacturing interior goods, shoes, clothing, etc., with an appearance and quality almost similar to those produced using genuine leather. Effects of the Invention According to the present invention, as described above, it is possible to produce artificial leather from a porous synthetic sheet material that has the same appearance, hardness, and feel as genuine leather, and has low flammability. Become. Examples Examples of the present invention will be shown below, but the invention is not limited thereto. (1) Example 1 and Comparative Tests 1 and 2 Example 1 12 strips of porous synthetic sheet material (see Figure 1) with a length of 10 m were folded and 12 strips of 250×
They were tied into bundles of 120 x 120 cm and stored in a rotating drum with a volume of approximately 5.6 m ² . The material used is calf skin.
It consisted of a porous polyurethane resin layer covered with a dense polyurethane resin layer that was pressed to resemble leather. The porous polyurethane layer contained a large number of polyester fibers extending in each direction and slidingly housed within the polyurethane matrix. This sheet material has a thickness of
It is 1.2mm and was produced and sold by Kuraray Co., Ltd. After the sheet material was inserted into the drum, 650 liters of water containing a surfactant was added to the drum.
The temperature of the solution was 60°C. And the drums
After spinning for 20 minutes at a speed of 15 rpm, the aqueous solution of surfactant was drained and contained 30% iron sulfate by weight.
Pour 650 liters of solution into the drum and check the pH of the solution.
The level was increased to 3.2 and the temperature of the solution was increased to 60°C. Next, after rotating the drum for about 40 minutes,
Add 10N of NaOH to raise the pH to 7.1 and raise the temperature to 60℃
This caused Fe(OH) ₃ to precipitate in the form of numerous aggregates. Then, after rinsing thoroughly with water and draining the spent solution, 650 liters of an aqueous solution of asparagine aldehyde, 6% by weight, was added to the rotating drum. And the drum 42
After spinning for a minute, the solution was drained and, in a still rotating drum, a solution of 650 liters of a 30% by weight sulfurized fatty acid ester (approximately 17-22 carbon atoms) was added. , at a temperature of 60℃
The sheet material was processed for 45 minutes. After this process,
The sheet material is heated to 3% in a rotating drum.
An aqueous solution of BASACRIL (registered trademark) at a temperature of 40°C.
for 55 minutes, followed by 1 hour at a temperature of 60°C and rinsed thoroughly. After this, the sheet material is transferred to PIROFLAM with a weight ratio of 60% in a rotating drum.
treatment with 252.5 liters of an aqueous solution of ® for 30 minutes, followed by an aqueous solution of 30% by weight PIROFLAM and 20% by weight TRIANOL SP®.
56.25 liters for 15 minutes. And 6rpm
The sheet material was dried with hot air at 60°C in a rotating drum. Comparative Test 1 The sheet material used in Example 1 was divided into 20 20 x 20 cm test pieces after the treatment in Example 1, and tanned pieces of the same size were tested for resistance to tension, abrasion and bending. A comparative test was conducted with a corresponding specimen of cowhide. The results are shown in Table 1.

[Table] Comparative Test 2 The material used in Example 1 before and after treatment was divided into 20 x 20 cm test pieces and made into US Federal Standard No. 3.02 (horizontal test piece). We then conducted a combustion test. A comparative test was conducted between four treated specimens dyed in different colors and four untreated specimens. Table 2 shows the results expressed in combustion rate (mm/min).

[Table] (2) Example 2 Synthetic material strip with a length of 10 m similar to Example 1
Twelve pieces were treated in substantially the same manner as in Example 1, except that chromium sulfate was used in place of the iron sulfate used in Example 1. The finished material is Example 1
It also had excellent firmness and feel and satisfactory appearance. (3) Example 3 The materials used in Example 1 and Example 2 were treated in substantially the same manner as in Example 1, but in Example 1.
An iron salt solution was used instead of the iron sulfate used in . The material after treatment was almost the same as in Example 1. (4) Example 4 The material used in Example 1 was treated in substantially the same manner as in Example 1, except that glutamic dialdehyde was used in place of the asparagine aldehyde used in Example 1. The resulting material had a high degree of flexibility and a fairly good appearance. (5) Example 5 The treatment described in Example 1 was applied to a two-layer sheet material, 0.8 mm thick, consisting of a polyurethane foam sheet covered with a dense polyurethane film of the type commonly used for vehicle sun coverings. It was applied to The resulting product showed similar results to those shown in Tables 1 and 2 in Comparative Tests 1 and 2, but was of lower quality than the final product in Example 1.

[Brief explanation of the drawing]

Figure 1 is a microscopic photograph showing the shape of fibers in a commercially available synthetic sheet material called "imitation leather," and Figure 2 is a microscopic photograph showing the shape of fibers in artificial leather manufactured according to the present invention. It's a photo.

Claims (1)

[Claims] 1. A porous polyurethane matrix layer in which polyester and/or polyethylene fibers are embedded, and a pressed polyurethane resin laminated to the matrix layer and patterned to resemble genuine leather. In a method of chemically processing a type of porous synthetic sheet material consisting of a cover film to produce artificial leather in the same way as genuine leather, the synthetic sheet material is Treating the synthetic sheet material with an aqueous solution of a metal salt of at least one metal selected from the above so that the aqueous salt solution penetrates substantially the entire synthetic sheet material, and after the completion of the salt solution treatment, by adding a strong base, The PH value of the salt solution is increased to precipitate the corresponding hydroxide of the metal salt in the form of a gel into the pores of the synthetic sheet material, and then the synthetic sheet material is treated with mineral oil and/or fatty acids. 1. A method for producing artificial leather, which comprises applying an oil treatment consisting of treatment with an emulsion of ester. 2. The method for producing artificial leather according to claim 1, characterized in that, after the precipitation step, the synthetic sheet material is treated in an aqueous solution of dialdehyde or polyaldehyde. 3. The method for producing artificial leather according to claim 1 or 2, wherein the metal salt is a sulfate. 4. Using synthetic sheet material with a thickness of 0.3 to 2 mm, characterized in that the synthetic sheet material is collected and bundled into suitable sizes for loading into a rotating drum of the type used for tanning genuine leather, A method for producing artificial leather according to any one of claims 1 to 3. 5. The synthetic sheet material is placed in a rotating drum of the type used to tan genuine leather and treated in an aqueous solution of a surfactant, then in a trivalent metal sulfate solution, and treated in a solution of a trivalent metal sulfate. The PH value is initially kept at about 3.2, then NaOH is added to the tanning solution to increase the PH value to about 7-7.5 so that the corresponding hydroxide is precipitated, and then the above synthetic sheet material is washed. 2. The method for producing artificial leather according to claim 1, wherein the artificial leather is treated in a 5 to 10% dialdehyde solution. 6 After dialdehyde treatment, the synthetic sheet material is oiled with an oil solution containing 30% sulfur by weight, dyed with a suitable colorant, washed, treated in a fire retardant treatment solution and finally 6. The method for manufacturing artificial leather according to claim 5, wherein the artificial leather is treated in a softening solution to which the fire prevention treatment solution is added. 7. The matrix of the synthetic sheet material is comprised of a porous polyurethane foam embedded with polyester and/or polyethylene fibers, and the synthetic sheet material is combined with at least one metal complex colorant for the polyester fibers and a colorant for the polyurethane resin. Dyeing using a 3% by weight solution of a mixture with at least one metal complex colorant, the coloring solution being initially maintained at about 40°C and after at least 1 hour of treatment the temperature is brought to about 60°C. 7. The method for producing artificial leather according to claim 6, which comprises: 8 The above synthetic sheet material is finally dried in hot air,
The method for producing artificial leather according to any one of claims 1 to 7, characterized in that the artificial leather is wound up.