Base material for roof underlayment

Abstract

To provide a roof underlayment that offers good workability and possesses sufficient mechanical strength for practical use. [Solution] The base material for the roof underlayment is a nonwoven fabric made of continuous fibers impregnated with asphalt. The nonwoven fabric is formed by heat-sealing the continuous fibers together, and the heat-sealing parts have a continuous woven pattern. The thermoplastic resin constituting the continuous fibers is polyethylene terephthalate, and the thermoplastic resin contains carbon black. The basis weight of the nonwoven fabric is 80-140 g / m². 2 Therefore, the single fiber fineness of the continuous fiber is less than 4 decitex.

Description

[Technical Field]

[0001] This invention relates to a roof underlayment that is laid beneath roofing materials in ordinary houses and used as an auxiliary waterproofing material. [Background technology]

[0002] In general, the roofs of typical houses in Japan have a structure in which a waterproofing sheet or asphalt roofing underlayment is interposed between the roofing base material, such as plywood or sheathing boards, and the roofing material, such as tiles, for waterproofing purposes.

[0003] Patent Document 1 discloses a spunbond nonwoven fabric for asphalt roofing substrates made of polyester fibers with specific parameters for the degree of fiber orientation on one surface and the degree of fiber orientation on the other surface. It is described that by specifying the degree of fiber orientation, the uniformity of the basis weight is improved and the asphalt impregnation processability is enhanced. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2024-65357 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0005] In Patent Document 1, the spunbond nonwoven fabric is formed by heat-sealing the constituent fibers together through heat embossing, thereby achieving strength suitable for practical use. Here, the shape of the heat-sealed areas created by heat embossing is circular, elliptical, square, etc., and there are many such point-like heat-sealed areas dispersed throughout the fabric.

[0006] Nonwoven fabrics in which constituent fibers are integrated by dot-like heat-sealed joints have numerous heat-sealed joints dispersed throughout, resulting in continuous non-heat-sealed areas. In these continuous non-heat-sealed areas, the fibers have a degree of freedom, making them prone to shrinkage due to high temperatures during processing, such as impregnation with molten, high-temperature asphalt, thus posing a problem for workability. Furthermore, when laying asphalt roofing obtained after asphalt impregnation as an underlayment, the edges of adjacent asphalt roofing pieces are overlapped and joined during installation. However, because the heat-sealed joints are dispersed and the non-heat-sealed areas are continuous, the material becomes bulky, resulting in poor adhesion at the overlapping joints and poor workability on site.

[0007] The present invention aims to provide a base material for roof underlayment that has good processability and workability. [Means for solving the problem]

[0008] The present invention achieves the above objectives, and the present invention is a base material for roof underlayment, comprising a nonwoven fabric made of continuous fibers impregnated with asphalt. A nonwoven fabric made of continuous fibers is a nonwoven fabric in which a large number of continuous fibers made of thermoplastic resin are deposited and the continuous fibers are integrated with each other by heat-sealing joints. The heat-sealed portions are continuous, and these continuous heat-sealed portions surround the non-heat-sealed portions, and there are numerous non-heat-sealed portions surrounded by the continuous heat-sealed portions. The thermoplastic resin constituting the continuous fibers is polyethylene terephthalate, and the thermoplastic resin contains carbon black. Nonwoven fabric basis weight: 80-140 g / m² 2 The gist of this invention is a base material for roof underlayment, characterized in that the single fiber fineness of the continuous fibers is less than 4 decitex.

[0009] The base material of the roof underlayment of the present invention is a nonwoven fabric made of continuous fibers impregnated with asphalt, and the nonwoven fabric is a nonwoven fabric in which a large number of continuous fibers made of thermoplastic resin are deposited and the continuous fibers are integrated with each other by heat-sealing portions.

[0010] The thermoplastic resin that makes up the continuous fibers is polyethylene terephthalate. Polyethylene terephthalate has a melting point of approximately 260°C and excellent heat resistance, so it can withstand the heat when impregnating with molten, high-temperature asphalt, and it also has excellent mechanical strength.

[0011] The thermoplastic resin constituting the continuous fibers contains carbon black. The inclusion of carbon black in the thermoplastic resin results in a stronger bond at the heat-sealed joints, improving strength. The amount of carbon black contained in the thermoplastic resin is preferably about 0.5 to 2.0 parts by mass per 100 parts by mass of the thermoplastic resin. A carbon black content of 0.5 parts by mass or more allows for a better improvement in the strength of the heat-sealed joints, while a carbon black content of 2.0 parts by mass or less maintains the strength of the continuous fibers themselves and allows for good spinning without impairing the spinnability during fiber production.

[0012] A good method for incorporating carbon black into polyethylene terephthalate is to mix and knead it using a measuring mixer or similar device until the desired carbon black content is achieved. For example, a masterbatch made by kneading 20-40% by mass of carbon into polyethylene terephthalate and polyethylene terephthalate chips can be dry-blended to achieve the desired carbon black content.

[0013] Furthermore, the thermoplastic resin constituting the continuous fibers may contain any additives such as matting agents, pigments, flame retardants, deodorants, antistatic agents, antioxidants, ultraviolet absorbers, and antibacterial agents, to the extent that they do not hinder the objectives of the present invention.

[0014] In this invention, the basis weight of the nonwoven fabric is 80 to 140 g / m². 2 The nonwoven fabric has a basis weight of 80 g / m². 2 As a result of the above, it is possible to properly impregnate the material with the amount of asphalt necessary to fully exhibit the waterproofing function required for roof underlayment, while maintaining a basis weight of 140g / m². 2As a result of the following, the thickness does not become excessive, allowing for good maintenance of strong bonding strength in the heat-sealed area. In addition, the material weight is not excessive, allowing for weight reduction, making it easier for workers to carry and apply on roofs, thus improving work efficiency.

[0015] The single fiber fineness of the continuous fibers constituting the nonwoven fabric is less than 4 decitex. Because the number of fibers per unit mass is higher when the single fiber fineness is less than 4 decitex, there are more bonding points between fibers in the heat-sealed area, resulting in improved adhesive strength in the heat-sealed area and superior nonwoven fabric strength. When the single fiber fineness is 4 decitex or higher, the number of bonding points between fibers decreases, making it difficult to improve strength. Furthermore, considering the strength of the fibers themselves, a lower limit of 2 decitex for the single fiber fineness is preferable. More preferably, the single fiber fineness of the continuous fibers constituting the nonwoven fabric is 2.5 to 3.8 decitex.

[0016] In nonwoven fabrics, the shape of the heat-sealed portion is such that the heat-sealed portion is continuous, the continuous heat-sealed portion surrounds the non-heat-sealed portion, and there are numerous non-heat-sealed portions surrounded by the continuous heat-sealed portion. In other words, in the present invention, the shape of the partially heat-sealed portion of the nonwoven fabric is such that the heat-sealed portion is not scattered as points, but rather is continuous, and it is important that the non-heat-sealed portions surrounded by the continuous heat-sealed portion are scattered. In the case of a heat-sealed shape where the heat-sealed portion is scattered as points, the non-heat-sealed portions are continuous, which gives the fibers a degree of freedom and makes them more susceptible to thermal shrinkage at high temperatures. On the other hand, in the present invention, non-heat-sealed areas exist in a point-like manner, and continuous heat-sealed areas surround these non-heat-sealed areas. As a result, the continuous heat-sealed areas effectively restrain the continuous fibers, making them less susceptible to thermal shrinkage at high temperatures and resulting in excellent dimensional stability. This also makes the nonwoven fabric less susceptible to thermal shrinkage during impregnation processing with molten, high-temperature asphalt, resulting in good dimensional stability and good processability. This allows for increased production speed and efficient processing in asphalt impregnation processing and other processes. Furthermore, while roof underlayment is typically laid by unwinding a roll of long lengths of underlayment on the roof and overlapping the longitudinal ends of adjacent long lengths, the continuous shape of the heat-sealed areas in the nonwoven fabric constituting the base material allows the underlayment using this base material to adhere well and bond even at overlapping ends, making it easy to bond, improving on-site workability, and ensuring good waterproofing at the overlapping areas.

[0017] A preferred shape for the heat-sealable portion of the nonwoven fabric is, for example, a woven pattern as shown in Figure 1. Figure 1 shows a plain weave pattern in which rectangular non-heat-sealable portions are arranged alternately in the left, right, up, and down directions, with some having their major axes oriented toward the machine direction and others having their major axes oriented perpendicular to the machine direction. The heat-sealable portions surround and are continuous with multiple rectangular non-heat-sealable portions. In Figure 1, the non-heat-sealable portions are rectangular, but the corners of the rectangles may be rounded, and as shown in Figure 2, the non-heat-sealable portions may also be elliptical in shape.

[0018] The area ratio of the thermocompression bonding part is preferably 25 to 50%. The area ratio of the thermocompression bonding part is the ratio of the area of the thermocompression bonding part to the area of the non-woven fabric. By setting the area ratio of the thermocompression bonding part to 25 to 50%, the dimensional stability is good, fiber fluff is less likely to occur, and the workability is good. Also, when the area ratio of the thermocompression bonding part is 25 to 50%, in other words, the area ratio of the non-thermocompression bonding part is 75 to 50%, and at the location where these fibers exist without being thermocompression bonded (non-thermocompression bonding part), it is also possible to have voids that can hold asphalt well.

[0019] The above-mentioned thermocompression bonding part can be imparted by passing it through a thermal embossing device. The thermal embossing device consists of an embossing roll and a flat roll. The embossing roll has concavo-convex parts on the roll surface that impart the thermocompression bonding part to the non-woven fabric. A continuous convex part surrounds the concave part, and a pattern engraving with a large number of concave parts surrounded by the convex part is used. And a thermocompression bonding part is formed at the location where it abuts against the convex part. In the embossing roll, the area ratio occupied by the convex part (the ratio of the area occupied by the convex part to the surface of the embossing roll) is preferably 25 to 50% as in the area ratio of the thermocompression bonding part imparted to the non-woven fabric.

[0020] The non-woven fabric may be one to which a binder resin is applied. Examples of the binder resin include thermosetting resins such as melamine resins, acrylic resins, and epoxy resins, and thermoplastic resins such as polyvinyl alcohol resins and polyurethane resins. When using a thermoplastic resin as the binder resin, it is preferable to use a crosslinked one in consideration of waterproofness and heat resistance.

[0021] The base material of the under-roof covering material is the above-mentioned non-woven fabric impregnated with asphalt. As the basis weight of the non-woven fabric and the basis weight of the impregnated asphalt, about 100 to 1000 parts by mass is preferable with respect to 100 parts by mass of the non-woven fabric. If the proportion of asphalt is small, there is a risk of deterioration in waterproofness. On the other hand, if the proportion of asphalt is too large, the weight of the obtained under-roof covering material becomes large, and there are concerns about handling properties.

[0022] The under - roof covering material has an asphalt layer provided on at least one side of the base material of the under - roof covering material of the present invention. Also, a mineral powder or granular material, or a resin layer may be provided on the asphalt layer to form the under - roof covering material.

[0023] The base material of the under - roof covering material of the present invention can be manufactured by the following method.

[0024] A masterbatch obtained by kneading carbon black into polyethylene terephthalate and polyethylene terephthalate chips are dry - blended so as to have a desired carbon black content. Using this, melt - spinning is carried out to obtain single - phase fibers, and they are manufactured by the spunbond method. Specifically, while taking up a continuous fiber bundle using air pressure, it is stretched, opened electrostatically by a method such as corona discharge, and a large number of continuous fiber groups are deposited on a moving collecting surface to obtain a continuous fiber web with a basis weight of 80 - 140 g / m 2 and then heat embossing is performed.

[0025] The single - fiber fineness of the continuous fiber is set appropriately by the single - hole discharge amount during melt - spinning and the take - up speed during take - up so that it is less than 4 dtex. The take - up speed is preferably set to 2000 - 5000 m / min, and more preferably 3000 - 5000 m / min. When the take - up speed is 2000 m / min or more, molecular orientation in the yarn is promoted, so it is difficult to thermally shrink. On the other hand, when the take - up speed is 5000 m / min or less, the spinning stability is good.

[0026] A group of numerous continuous fibers, thinned to the desired fineness by traction, are opened using a known fiber-opening device, and then opened and deposited on a movable collection surface such as a screen conveyor to form a continuous fiber web. This web is then passed through a thermal embossing device to perform thermal embossing, obtaining a nonwoven fabric in which the continuous fibers are integrated by heat-sealed sections. The thermal embossing device used consists of an embossing roll with the aforementioned engraved pattern of raised and recessed areas and a flat roll. The heat treatment conditions in the thermal embossing device should be set to a temperature of 220-240°C for both rolls, and no gap (clearance) should be provided between the rolls. This is because the fibers in contact with the thermal embossed section are well heat-sealed by eliminating the gap between the rolls. Furthermore, after partially forming heat-sealed sections by thermal embossing, calendering may be performed on the surface of the nonwoven fabric using a flat roll by pressure and / or heat, for the purpose of correcting the thickness of the non-heat-sealed sections and suppressing fibers protruding from the non-heat-sealed sections.

[0027] The nonwoven fabric obtained as described above is impregnated with molten asphalt and integrated to obtain the base material for the roof underlayment of the present invention. The amount of asphalt impregnation is as described above. [Effects of the Invention]

[0028] The base material of the roof underlayment of the present invention has a heat-sealed portion of a specific shape, and can provide a roof underlayment with good processability and workability. [Brief explanation of the drawing]

[0029] [Figure 1] This diagram schematically shows the shape of the heat-sealed portion applied to the nonwoven fabric. [Figure 2] This diagram schematically shows another example of the shape of a heat-sealed portion applied to a nonwoven fabric. [Examples]

[0030] Next, the present invention will be specifically described based on examples, but the present invention is not limited in any way by these examples. In the examples, each characteristic value was measured by the following method. (1) Basis weight (g / m 2 Ten 10cm x 10cm sample pieces were prepared, the mass (g) of each sample piece under standard conditions was weighed, and the average value obtained was converted to a unit area to determine the basis weight (g / m²) of the nonwoven fabric. 2 ) (2) Single fiber fineness (decitex): A continuous fiber web was observed using a microscope, and the fiber diameter of 50 fibers was measured individually. The average value of the fineness obtained by correcting for density was defined as the single fiber fineness (decitex). (3) Thickness (μm): Measured at a pressure of 4 kPa based on the method described in JIS L 1913 (2010) Method A. (4) Tensile strength (N / 5cm width) and tensile elongation (%): Ten strip-shaped test pieces measuring 5cm wide x 20cm long were prepared, and tensile tests were performed using a constant-speed elongation tensile testing machine (Tensilon UTM-4-1-100, manufactured by Orientec Co., Ltd.) with a gripping distance of 10cm and a tensile speed of 20cm / min, and measured in accordance with JIS L1913. The average value of the 10 points was used as the tensile strength (N / 5cm width) and tensile elongation (%). Tensile strength was determined in both the longitudinal direction (machine direction (MD direction)) and the transverse direction (direction perpendicular to the machine direction (CD direction)). (5) Stress at 3% elongation (N / 5cm width): For the load shown at 5% elongation in the elongation-load curve obtained during the tensile strength measurement described above, the average value of 10 samples was calculated and defined as the stress at 5% elongation (N / 5cm width). (6) Thermal shrinkage rate (%): Three test specimens measuring 15 cm (machine direction) × 15 cm (width direction) were taken. A 15 cm straight line parallel to the width direction was marked at the midpoint of the machine direction of each specimen (7.5 cm from the end in the machine direction), and a 15 cm straight line parallel to the machine direction was marked at the midpoint of the width direction (7.5 cm from the end in the width direction). These specimens were placed in a 180°C constant temperature bath, suspended by holding the corners so that they were perpendicular to the machine direction, and left for 30 minutes. After being removed and cooled to room temperature, the lengths of the two sides of the specimen in the machine direction and the length of the line marked parallel to the machine direction at the midpoint of the width direction were measured. The sum of these three lengths was taken as the total length after heat treatment, and the thermal shrinkage rate in the machine direction was calculated using the following formula. Thermal shrinkage rate (%) = 100 × (45 - total length after heat treatment) / 45 Similarly, the thermal shrinkage rate in the width direction was also calculated. This was determined for each of the three sample pieces, and the average value was calculated to determine the thermal shrinkage rate in the machine direction and width direction. (7) Abrasion resistance when wet: After spraying the obtained nonwoven fabric with water using a spray bottle until the surface was sufficiently wet, approximately 60 seconds later, the surface of the nonwoven fabric was rubbed with a finger, and the condition of the nonwoven fabric surface was visually observed and evaluated according to the following criteria. ◎: Even after rubbing back and forth more than 10 times, there was no change in the surface of the nonwoven fabric, and no loosening of fibers was observed. After rubbing back and forth about 10 times, loose fibers were observed on the surface of the nonwoven fabric in the rubbed area. ×: After rubbing back and forth 1 to 3 times, fibers began to lift from the surface of the nonwoven fabric.

[0031] Example 1 A resin pellet of polyethylene terephthalate with an intrinsic viscosity [η] of 0.70 and a melting point of 260°C was prepared, along with a masterbatch made by kneading carbon black into the polyethylene terephthalate. A dry blend was then used, with the carbon black concentration being 1.1 parts by mass per 100 parts by mass of polyethylene terephthalate.

[0032] The dry-blended resin pellets were supplied to the spinning hole, and melt spinning was performed at a spinning temperature of 295°C. After melt spinning, the fibers were taken up and thinned using a suction device (traction speed 4500 m / min), and after the continuous yarn group discharged from the suction device was opened, a large number of polyethylene terephthalate continuous fibers (single fiber fineness 3.5 decitex) were accumulated on a moving collection surface to obtain a continuous fiber web.

[0033] Next, the continuous fiber web was passed through a thermal embossing device to perform thermal embossing. The thermal embossing device used a pattern engraving in which continuous protrusions surround recesses, and in which numerous recesses are surrounded by the protrusions. It consisted of an embossing roll (protrusion area ratio 37%) and a flat roll, both of which had an engraved pattern that created the heat-sealed areas shown in Figure 2. Both rolls were set to a surface temperature of 230°C, and no gap (clearance) was provided between the rolls. Thermal embossing was performed on the continuous fiber web to partially form heat-sealed areas.

[0034] After partially forming heat-sealed sections, the nonwoven fabric is immersed in a binder resin solution containing polyvinyl alcohol resin and a crosslinking agent (waterproofing agent) (the ratio of polyvinyl alcohol resin to crosslinking agent is 32:5). The squeezing ratio is adjusted so that for every 100 parts by mass of nonwoven fabric, there are 16 parts by mass of polyvinyl alcohol resin and 2.5 parts by mass of crosslinking agent. The nonwoven fabric impregnated with the binder resin solution is then dried and heat-set to a basis weight of 100 g / m². 2 We obtained a nonwoven fabric.

[0035] The physical properties of the obtained nonwoven fabric are shown in Table 1.

[0036] Furthermore, the obtained nonwoven fabric was impregnated with asphalt molten at 200°C in a ratio of 200 parts by mass of asphalt per 100 parts by mass of nonwoven fabric to obtain a base material for roof underlayment. During the impregnation process, no thermal shrinkage occurred, the base material exhibited excellent processability and smoothness, and when the edges of the obtained base materials were overlapped, the bonding properties were good.

[0037] Comparative Example 1 In Example 1, only resin pellets of polyethylene terephthalate having an intrinsic viscosity [η] of 0.70 and a melting point of 260°C without containing carbon black were used, polyethylene terephthalate continuous fibers (single fiber fineness: 4.4 dtex) were obtained, and a non-woven fabric having a basis weight of 100 g / m was obtained in the same manner as in Example 1 except that a gap (clearance) between the rolls was provided during the thermo-embossing process. 2 The obtained non-woven fabric had physical properties as shown in Table 1. Compared with the non-woven fabric obtained in the example, the obtained non-woven fabric was inferior in strength in the machine direction, inferior in abrasion resistance when wet, showed slightly more heat shrinkage in the impregnation process with asphalt, was slightly inferior in smoothness, and was also slightly inferior in joining property when the ends of the obtained base materials were overlapped.

[0038]

[0039] Comparative Example 2 In Example 1, as the embossing roll in the thermo-embossing device, an embossing roll having an embossing pattern in which convex portions are engraved in a scattered pattern and forming a large number of circular thermocompression bonding portions in a scattered pattern (area ratio of convex portions: 13%) was used, and a non-woven fabric having a basis weight of 100 g / m was obtained in the same manner as in Example 1 except that a gap (clearance) between the rolls was provided during the thermo-embossing process. 2 The obtained non-woven fabric had physical properties as shown in Table 1. Although the abrasion resistance when wet of the obtained non-woven fabric was good, the heat shrinkage rate was large, heat shrinkage was observed in the impregnation process with asphalt, it was also inferior in smoothness, and it was inferior in processability. Also, when the ends of the obtained base materials were overlapped, it was inferior in joining property.

[0040]

[0041] [[ID=2()]]

Table 1

Claims

1. It is a base material for roof underlayment, and is made of a nonwoven fabric consisting of continuous fibers impregnated with asphalt. A nonwoven fabric made of continuous fibers is a nonwoven fabric in which a large number of continuous fibers made of thermoplastic resin are deposited and the continuous fibers are integrated with each other by heat-sealing joints. The heat-sealed portions are continuous, and these continuous heat-sealed portions surround the non-heat-sealed portions, and there are numerous non-heat-sealed portions surrounded by the continuous heat-sealed portions. The thermoplastic resin constituting the continuous fibers is polyethylene terephthalate, and the thermoplastic resin contains carbon black. Nonwoven fabric basis weight: 80-140 g / m ２ A base material for roof underlayment, characterized in that the single fiber fineness of the continuous fibers is less than 4 decitex.

2. The base material for the roof underlayment according to claim 1, characterized in that a binder resin is attached to a nonwoven fabric.

3. A roof underlayment characterized in that an asphalt layer is laminated on at least one side of the base material according to claim 1 or 2.

4. It consists of polyethylene terephthalate containing carbon black, with numerous continuous fibers having a single fiber fineness of less than 4 decitex, and a basis weight of 80-140 g / m². ２ A continuous fiber web is obtained, Next, when the continuous fiber web is passed through a thermal embossing apparatus consisting of an embossing roll and a flat roll to perform thermal embossing, A nonwoven fabric is obtained in which continuous fibers are integrated by heat-sealing sections, using an embossing roll with a pattern engraved in which continuous protrusions surround recesses, and numerous recesses surrounded by protrusions. A method for manufacturing a base material for roof underlayment, characterized by impregnating the nonwoven fabric with molten asphalt and integrating it.

5. The method for manufacturing a base material for roof underlayment according to claim 4, characterized in that no clearance is provided between the embossing roll and the flat roll when applying heat embossing.

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