JPS6317147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for simultaneously and sequentially reinforcing and coating nonwoven fabrics using a binder and an adhesive, wherein the binder is applied from one side to the adhesive printed on the opposite side. are simultaneously counterprinted in the form of overlapping partial areas, each of which relates to a spaced apart one from the other.

Methods of this type are known from the prior art. Binders and adhesives are then applied when the nonwoven is passed between a pair of gravure or screen rolls. The printed images produced on both sides are therefore identical and do not correspond to the intended use of both materials.

The binder first bonds the fibers of the nonwoven fabric to each other;
This serves to impart strength to the nonwoven fabric. The strength increases as more fibers are bonded together. It is therefore desirable that the binder penetrates into the interior of the treated nonwoven fabric and that its reinforcement is at the same time distributed as evenly as possible over the entire cross section. In particular, polymeric substances capable of cross-linking polymerization are actually used as binders.

Adhesives applied to the surface of the fixed interlining, on the other hand, serve for adhesion to other fabrics. Typical adhesives are thermoplastic materials, and activation is caused by the application of heat and pressure, for example with the aid of an iron. Unlike binders, adhesives therefore penetrate as little as possible into the interior of the nonwoven fabric used and are utilized as completely and intensively as possible for adhesion with the superimposed surfaces on the opposite side during ironing. It is desirable that

The method mentioned at the outset makes it possible to apply the binder and the adhesive in congruent form to the top and bottom sides of the nonwoven fabric used. However, the same printing method used during treatment of the top and bottom surfaces results in the same indentation force, making it extremely difficult to achieve substantially different indentations of the desired bonding agent and adhesive. A relative correction of the size of the applied part area is not possible and higher printing speeds lead to blurring of the printed image, especially in the case of processing non-woven materials that have not been previously reinforced, and therefore also to the fixed interlining obtained. There is a possibility that the various characteristics of

According to JP-A-55-140587 filed by the present applicant, it is shown that the degree of press-fitting from the upper and lower surfaces can be changed by using, for example, a letterpress printing cylinder and a screen printing cylinder. .
However, there are still problems in printing in such a way that the adhesive does not impregnate the inside of the nonwoven fabric, while the binder sufficiently impregnates the inside of the nonwoven fabric. This is because when printing is performed in this manner, the binder flows out or the applied shape is distorted due to its fluidity, making it impossible to obtain a fully satisfactory result.

A method is known from European Patent Application No. 12776 which makes it possible to strengthen non-woven fabrics by printing with a UV-curable binder and subsequent irradiation with a high-pressure mercury lamp at working speeds of more than 50 m/min. Application of adhesive is not claimed.

The present invention further comprises the method mentioned at the outset, in which simultaneous, sequential printing of binder and adhesive in the form of partial areas with congruent center lines on both sides of an unreinforced nonwoven fabric results in an accurate printed image. This is the basis for the task of developing a product in such a way that it is possible to vary the specific application amount on both sides as well as the degree of indentation on both sides.

This object is achieved according to the invention by the features of the first patent claim. Advantageous embodiments are described in the subclaims.

In the method according to the invention, a binder which can be cross-linked by ultraviolet radiation is printed from the underside of the non-woven fabric onto a thermoplastic adhesive applied to its upper side according to the powder spot method or screen printing method. . The binder is subsequently cross-polymerized by means of UV radiation, the radiation dose being at the same time resulting in a geometrical self-stabilization of the shape of the adhesive surface and at the same time reducing the amount of radiation during transport and in the subsequent sintering path or dryer. It is chosen to be sufficient with regard to preventing run-off during processing and therefore also blurring of the printed image.

After printing, the nonwoven is irradiated with ultraviolet radiation with excess energy to achieve complete cross-linking polymerization of the binder, which is distributed over the cross section. This excess advantageously accounts for more than half of the electrical energy used and is essentially due to the adhesive particles which are raised in relief from the surface of the non-woven fabric over the binder-containing partial area according to the invention. The partial area becomes,
To the extent that it prevents the shape from changing, especially from flowing out, during transfer to the subsequent dryer or subsequent heat treatment chamber.
Used for adhesion to each other or to nonwoven surfaces. The electrical or radiation energy used ensures complete crosslinking of the binder pressed into the nonwoven within the partial area and simultaneous stabilization of the adhesive partial area. A particularly advantageous ratio of ultraviolet radiation to thermal radiation is obtained when the medium-pressure and high-pressure mercury lamp radiation is directed onto the printed surface of the nonwoven from both sides without special filters and/or special cooling. The use of an excess of the required energy distribution is generally not disadvantageous, but rather favors good contour sharpness of the printed images obtained on both sides at the highest operating speeds. It is an emphasizing advantage that this is maintained even when vibration or shaking movements are transmitted to the non-woven fabric by external influences. Suppression of vibrations etc. is often extremely difficult at the mentioned method stage, and the nonwoven fabric in question has a flat weight of 10
It should also be taken into account that with working widths of between 50 g/m ² and more than 1 m, they are often very sensitive even to air vibrations.

The printing methods used for the application of adhesives and binders belong to fundamentally different classes, whereby both substances, which have to perform different kinds of tasks in their application, are applied in an advantageous mutual relationship. is achieved. Furthermore, at least one of the two counter-rotating printing rolls exhibits flexible properties, so that the asymmetry in the thickness or elasticity of the printed nonwoven is such that distortion of the resulting printed image is avoided. , it is important that they be offset.

The binder can be applied using a letterpress, lithographic or intaglio roll with a flexible mantle made of rubber.
Good press-in of the binder into the interior of the nonwoven fabric is achieved in all three cases. In addition, letterpress printing itself has the additional advantage of a particularly high surface elasticity and a good resistance to contamination by fiber components coming off the surface of the printed nonwoven.

In letterpress and lithographic printing, the specific application amount of binder can be continuously varied by adjusting the printing equipment used. Insofar as corresponding modifications are necessary when applying the intaglio printing method, it is necessary to use correspondingly modified printing rolls. Furthermore, modified printing rolls are required when modifying the size of partial areas in letterpress, planographic or intaglio printing. Modifications of this type can, for example, increase the diameter when ironing a fixed interlining with a less absorbent outer fabric in order to prevent the adhesive from penetrating into the interior of the interlining.

The adhesive can be printed on the nonwoven fabric in the form of a dry powder using the powder spot method or in the form of a powder suspended in a paste using the screen printing method. The powder spot method consumes less energy because the carrier liquid required for the screen printing application does not have to be removed again afterwards. However, the amount of adhesive applied per unit area cannot be changed continuously by simply changing the set angle of the doctor knife as in the case of screen printing, and a separate application roll is required. For decisive mass production with even specific application rates of adhesive, the powder spot method is therefore recommended, while screen printing is preferred for the production of fixed interlinings in small quantities with special adhesive properties. Ru.

In both cases all properly used adhesives can be processed. For example, those based on polyolefins, polyurethanes, copolyamides or copolyesters. Melting points generally range from 100 to 130°C. The particle size of the powder used must be relatively fine to enable sufficient mutual pre-adhesion by utilizing the excess energy from the UV-induced cross-polymerization of the binder. Good results are generally obtained for the powder point method when the maximum particle size is at least
This is achieved when it is less than 0.2 mm in 95% of cases and less than 0.1 mm in at least 95% of all cases in the case of dispersion printing methods.

Partial surfaces of binder or adhesive are printed on the top and bottom sides of the non-woven fabric in the same plane screen with center lines superimposed. These are formed relatively finely, for example, when the diameter is 0.4 to 0.7 mm, the distance between their centers can be 1 mm. In contrast, the fibers used in the production of fixed interlinings of this type have a length of at least 25 mm and their mutual relationship follows an irregular pattern. If no distortion of the nonwoven fabric is observed during processing in the printing device, it is assumed that all parameters are jointly involved.

Example 1 A non-woven fabric with a length of 25 g/m ² made of 100% polyester fibers (1.7 dtex/40 mm cutting length) is produced at a speed of 60 m/min by means of several card machines arranged in the longitudinal direction. The nonwoven fabric is passed through a pair of rolls placed opposite each other and heated to a surface temperature of 150 DEG C., and is compressed at a linear pressure of 15 kp/cm. Immediately thereafter, the nonwoven fabric is passed through the printing device according to FIG. The upper printing roll is a screen printing template 1 with a 25 mesh grid. The hole diameter is standardized to 0.45mm, and the template thickness is 0.19mm. A doctor knife 3 is provided in the screen printing roll, which can be adjusted to be tilted relative to the vertical.

This screen printing roll 1 is used to print an aqueous adhesive paste 2. This is the maximum particle diameter of 10
Contains 40% by weight of a ternary copolyamide powder consisting of laurin lactam, caprolactam and AH salt (of hexamethylene diamine adipate substrate), with a melting point of 115° C. to 80 μm, with a viscosity increased by the addition of acrylate thickener and ammonia has been adjusted to 15000mPassec. The amount applied to nonwoven fabric 4 is 30 when wet.
g/m ² and 12 g/m ² after drying.

The lower printing roll 5, ie the second roll from the top, is designed as a rubber letterpress roll. This rubber is stable to organic liquids and has a Shore A hardness of
It is 65. The pitch of the letterpress printing pattern is exactly the same as that of the screen printing roll, but the diameter of the printing area is 0.8 mm. The depth of the engraving is 0.4mm.

From a bath of prepolymer 6 preheated to 60°C, the following binder mixture is applied to a rubber dip roll 7 and also at 60°C.
The image is transferred to a rubber letterpress roll through a chrome plating transfer roll 8 which has been heated to 60 mesh gravure. The speed of the dipping roll 7 is such that the printing adhesion from the letterpress roll to the nonwoven fabric is 2.5 g/m ²
Adjust so that

Both printing rolls are adjusted so that the center points of the partial areas printed on both sides coincide and overlap.

The binder has the following composition: 70 parts epoxy acrylate 30 parts oligotriacrylate 20 benzophenone 1 benzyl dimethyl ketal 3 N-methyl diethanolamine 3 optical brightener 0.03 After leaving the printing device, the nonwoven is metallic. It is carried through a light-shielding passageway into the irradiation box by a conveyor belt made of
There, they were guided through two rows of high-pressure mercury lamps with a capacity of 200 W/cm, one from above and one from below. Curing of the binder is instantaneous. After leaving the irradiation box through a second light-tight passage, the nonwoven fabric is guided through a 15 m long tension frame where the circulating air temperature is 115°C.
The adhesive is final dried and final sintered.

At the back of the upholstery, a cutting device cuts off the edges on both sides of the strip material and divides it in the center, resulting in two 90 cm wide strips of interlining nonwoven fabric that can be sold directly.

The interlining nonwovens obtained are extremely soft and pleatable, have excellent washing and dry cleaning resistance, and can be processed satisfactorily in all conventional fixing devices.

Example 2 A horizontal non-woven fabric is unloaded onto a grid table by several card machines and horizontal machines which are perpendicular to the working direction of the machine. The area weight of the band-shaped nonwoven fabric that advances at this speed is 27 g/m ² , and the width of the band is 195 cm. The fiber mixture consists of: Highly wound polyamide fibers
1.7d, cutting length 40mm 40 parts Polyester fiber 1.6d, cutting length 40mm 30 parts Polyester fiber 1.6d, cutting length 40mm 30 parts This fibrous nonwoven fabric is
It is guided between a pair of heated rolls. Roll surface temperature is 190℃, linear pressure is 30kp/cm, peripheral speed is 25
m/min.

Immediately after passing the heated rolls, the nonwoven fabric is passed through the printing device of FIG.

The lower three rolls, the prepolymer tank, the composition and temperature of the prepolymer mixture, and the heating of the transfer roll are the same as in Example 1.

The upper roll is designed as a dust-printing roll. The printed pattern is formed as a 25 mesh dot array. The pitch is the letterpress rubber call 5 below.
It is exactly the same as the 25 mesh screen, and the printing area is 0.8 mm in diameter for the circular one.
The depth of the small hole is 0.25 mm and its diameter is 0.40 mm.

The powder roll is heated to a surface temperature of 68°C. Using this, the maximum particle diameter is 1 to 200μ, the melting range is 120μ.
A ternary copolyamide powder 10 at a temperature between 130°C and 130°C is applied.

At the same time, the UV-curable prepolymer binder mixture according to Example 1 is also applied from below to the same location on the strip by means of a rubber letterpress roll 5.
After leaving the printing device, the strip passes through the irradiation box described in Example 1, during which the binder is sufficiently cured and the adhesive surface is stabilized in shape. The already lightly pre-glued adhesive points are exposed to the subsequent infrared field (irradiation source temperature
Finally, it is sintered solidly at 400°C. After passing through the cooling roll, the strip material was cut into two strips each having a finished width of 90 cm and wound up in the same manner as in Example 1.

Particularly soft, multidirectional, bulky interlining nonwoven fabric with good pleatability and excellent resistance to washing and dry cleaning can be obtained.

The partial area made of bonding agent has a larger diameter in both embodiments than the partial area made of adhesive. This prevents the melting adhesive from penetrating into the fixing interlining during heat setting of the fixing interlining to a better extent than would be the case if the overlapping partial areas were of the same size.
In addition to the regular planar screens mentioned above, all other desired planar screens can also be implemented, for example subareas of distributed gratings with statistical orientation, which is often preferred. Besides circular, all other desired shapes are also possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a printing device for carrying out the method of the invention, and FIG. 2 is a diagram of a further printing device for carrying out the method of the invention. 1... Screen printing template, 2... Adhesive paste, 3... Doctor knife, 4... Nonwoven fabric material, 5... Lower printing roll, 6... Prepolymer, 7... Dipping roll, 8... Transfer roll, 9... Powder spot printing roll, 1
0...Copolyamide powder.

Claims (1)

[Scope of Claims] 1. A method for simultaneously and sequentially reinforcing and coating a non-woven fabric using a binder and an adhesive, the binder being overlapped from one side to the adhesive printed on the opposite side. A thermoplastic adhesive is applied to the upper side of the non-woven fabric according to the powder spot method or screen printing method, in the form of part areas that are printed simultaneously oppositely, each of which is spaced apart from each other. On the other hand, a binder that can be cross-linked and polymerized by ultraviolet rays is printed from the bottom side, and the printing of the binder is carried out so that the binder impregnates the inside of the nonwoven fabric and prevents the adhesive printed on the opposite side from impregnating the nonwoven fabric. irradiation with light in which 10 to 30% of the energy is contained in the form of ultraviolet radiation, the total power of the light being such that the binder is crosslinked and the adhesive is stabilized in its geometric distribution. A method characterized in that the nonwoven fabric is then finished by drying or by sintering the adhesive. 2. Process according to claim 1, characterized in that a medium- or high-pressure mercury lamp with a capacity of 80 watts/cm is used for the crosslinking polymerization of the binder and the stabilization of the adhesive. 3. Process according to claim 1 or 2, characterized in that the adhesive powder is processed in a screen printing method or a powder spot method with a maximum particle diameter of at least 95% between 0.1 and 0.2 mm. 4. A method according to any one of claims 1 to 3, characterized in that the binder and adhesive are printed on the non-woven fabric in uniform or non-uniform flat screens. 5. A method according to any one of claims 1 to 4, characterized in that the binder is printed with a larger area than the opposing adhesive.