JPS6366952B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sound insulating carpet backing resin composition, and more specifically to a sound insulating carpet backing resin that has improved processability, thermal stability, backing suitability, livability, etc. and is suitable for automobiles. This relates to a composition. Traditionally, carpet bucking methods include:
Broadly speaking, there are two types of carpets: those using latex and those using solid synthetic resin as raw materials.Carpets for automobiles are mainly manufactured using the latter method, which allows easy press molding to fit the shape of the car body. It came. Recently, in order to improve the comfort inside a car, there has been an increasing demand for an automobile carpet that has sound insulating properties that reduce noise from the floor. As a measure to reduce noise inside automobiles, efforts began to be made to increase the areal density of the backing layer and make it heavier to provide a sound insulation effect.
3904456, JP-A No. 54-110255, JP-A No. 55-118940, etc. In addition, an example of actually applying this concept to automobile carpets is U.S. Patent No. 4191798,
It is disclosed in JP-A-55-71734 and 55-113533,
Some companies have already developed specific products by combining ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) with a high content of vinyl acetate (hereinafter referred to as VAc) and calcium carbonate. However, the current product uses EVA with a high VAc content, so it has major drawbacks such as a low melting point, poor thermal stability, poor processability, and poor productivity. In addition, as a recent trend, air fresheners specifically designed for the interior of automobiles are being sold, and careful consideration has been given to the environment inside the vehicle. However, if EVA with a high VAc content is used for carpet bagging, In the summer, the inside of a closed car under direct sunlight becomes extremely hot, and the acetic acid odor characteristic of EVA becomes a problem. Furthermore, if the current base resin, EVA with a high VAc content, is used as a base, cheaper low-density polyethylene (hereinafter abbreviated as LDPE) can sufficiently solve the problems of thermal stability and odor. However, it has poor affinity with LDPE and CaCO ₃ , is brittle and easily cracked, and has a significant drop in fluidity, and has poor processability and resin properties compared to EVA with a high VAc.
It is significantly inferior to the combination with CaCO ₃ and cannot be used for sound insulation carpet backing. The present invention was made in view of the current situation, and was achieved as a result of intensive research aimed at solving the various drawbacks mentioned above. That is, according to the present invention, LDPE or VAc
About 60 to about 30 parts by weight of EVA containing less than 5% by weight and about 40 to about 40 parts by weight of a filler mainly composed of barium sulfate.
70 parts by weight essentially provides a sound insulating carpet backing resin composition and a sound insulating carpet in which this resin composition is backed on the back side of a carpet material. In the present invention, the resin composition for sound insulating carpet backing is essentially LDPE or VAc.
It combines low-content EVA with a filler whose main component is BaSO ₄ . The reason for combining LDPE or EVA with a low VAc content with barium sulfate is as follows. In other words, sound insulating carpet suitable for automobiles can have sound insulating properties even if fillers other than BaSO ₄ are added to LDPE, but the fillers themselves, which have a light specific gravity such as CaCO ₃ , talc, clay, etc. ,
Compared to BaSO ₄ , it is necessary to thicken the backing layer in order to obtain an areal density with satisfactory sound insulation properties, which not only causes a decrease in production speed but also reduces the volume ratio (Vol%) occupied by the filler in the composite resin. increases, the affinity between the resin and the filler is poor, it is brittle, the fluidity is significantly reduced, and the motor load increases during processing, making it practically unusable. In addition, filler materials such as zinc oxide, titanium oxide, and iron oxide, which have a relatively heavy specific gravity, are excellent in terms of sound insulation and backing thickness, but CaCO ₃ Like talc, it has problems and is virtually unusable. Furthermore, if the base resin is high-density polyethylene or polypropylene, it is even worse than LDPE in terms of processability, affinity, fluidity, brittleness, etc., and is completely impractical. However, by combining LDPE or EVA with a low VAc content and BaSO ₄ , it is possible to create a composite resin composition that has excellent thermal stability, bucking suitability, livability, sound insulation properties, etc. without impairing processability. It is possible to obtain. In the present invention, LDPE refers to one manufactured by a high-pressure method using an ordinary radical polymerization catalyst;
Alternatively, there is no particular restriction as long as it is produced by a gas phase method or a liquid phase method that does not use a radical polymerization catalyst, but in order to obtain better thread removal strength and sheet bending properties, preferably MI (ASTM,
D-1238 compliant) is 7 g/10 min or more, and density (ASTM, D-1505 compliant) is 0.930 g/cm ³ or less. Also, there are no particular restrictions on EVA as long as the VAc content is less than 5wt%.
Preferably, the MI is 7 for similar reasons to LDPE.
g/10min or more is better. EVA with a VAc content of 5% by weight or more has a high VAc content, resulting in a low melting point, poor thermal stability, strong odor, and a high motor load when extruding with an extruder. This tendency makes it unsuitable for the present invention. The proportion of filler in the resin composition is approximately 40−
About 70 parts by weight, but if it is less than 40 parts by weight,
In order to obtain the areal _density necessary for sound insulation, the backing layer must be too thick, leading to a decrease in productivity. This is because it is inferior and unsuitable for buffeting. Furthermore, there are no particular limitations on the method of obtaining the resin composition of the present invention, and when using an extruder,
You can dry blend the base resin such as LDPE with BaSO ₄ and then feed it, or you can weigh each of them and feed them directly without dry blending, or you can use other general methods. The composition may be obtained by using a mixing/kneading device such as a Banbury mixer or a mixing roll, which is a standard blending means, but it is preferable to obtain the composition so that the sheet has desired physical properties, bucking suitability, sound insulation properties, etc.
It is better to melt and mix uniformly. In the present invention, "filler whose main component is barium sulfate" means that the main component of the filler is BaSO ₄
is the main component in the filler
As long as the BaSO ₄ purity is in the range of 80% by weight or more, components (for example, impurities and other fillers) that do not interfere with the effects of the present invention can be contained at the same time. In addition, "essentially" means that the presence of each component is essential, and it means that the components may be included at the same time as long as they do not interfere with the effects of the present invention (for example, a small amount of additives, etc.). It is. There are no particular restrictions on the type of raw fabric used for the sound insulating carpet made using the composition of the present invention. Furthermore, there are no particular limitations on the method for producing the sound insulating carpet of the present invention from the raw fabric and the resin composition of the present invention, and a method may also be used in which the resin composition of the present invention is extruded from an extruder and then backed onto the carpet raw fabric. However, if desired, a sheet made of the composition may be laminated to provide sound insulation properties to a carpet material that has already been backed by another method. Further, the layer that imparts sound insulation properties to the carpet may be a layer of the composition, and the presence of the layer does not interfere with the effects of the present invention. When the resin composition for sound insulating carpet backing of the present invention is made into a sheet form and the sheet properties are measured,
The density is 1.3 g/cm ³ or more, the elongation at break is 50% or more, and in the sheet bending test, cracks do not easily occur even after repeated bending many times, and the sound insulation properties are good. Furthermore, when the resin composition of the present invention is extruded in the form of a sheet and pasted onto a carpet material to form a sound-insulating carpet, the motor load during extrusion is small, and it is easy to pull out one carpet pile from the sound-insulating carpet. The strength required for this (thread removal strength) also showed a large value of 1.3 kg or more, and the sound-insulating carpet prepared by backing the resin composition of the present invention on the original carpet had almost no odor. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Examples 1 to 3 LDPE [MI = 28, density = 0.9155, Asahi Dow Polyethylene H-6525] and BaSO ₄ [Varico # manufactured by Sosui Kasei Co., Ltd.
200] and 30
Using a mmφ extruder [L/D=28, slow compression type screw with tip damage], resin temperature was 150℃.
The composite resin composition was extruded and pelletized to obtain composite resin composition pellets having respective proportions. A compression sheet for evaluating the physical properties of a resin composition for sound insulating carpet backing was made from the pellets, and the density, stiffness (based on ASTM D-747), and elongation at break (based on ASTM D-1248) of the composite resin were determined. A sheet bending test was conducted. The density must be 1.3 g/cm ³ or more, and the elongation at break must be 50% or more. In addition, in the sheet bending test, a compression sheet with a thickness of 1.2 mm was repeatedly bent 180 degrees by hand, and the number of times until cracking was 10 or more was rated "◎", and the number of times until cracking was rated "◎", and those 5-9 times were rated "``〇'', 2-4 times as ``△'', and 1 time as ``x''. The satisfactory rank is
“◎” or “〇”. The evaluation results are shown in Table 1.
are summarized in the following. In addition, the composition sheets of Examples 2 and 3 further contained the first
Sound insulation was evaluated using the equipment shown in the figure. In the device shown in Figure 1, a bell 1 is installed at the bottom of a box 6 that is lined with a 3 mm thick lead plate 4 and exteriorized with a 20 mm plywood board 5. _A square opening 7 with a diameter of 150 mm is provided. The test sample 2 is placed on the upper periphery of this opening 7.
(200 x 200 mm) is placed and held by a presser frame 8 to be fixed. The distance l ₂ from the outside of the bottom of the box 6 to the sample 2 to be tested is 300 mm. Further, a sound level meter 3 is set above the sample 2 to be tested. The sound insulation characteristics of the sample 2 to be tested are measured by setting the condition as shown in FIG. 90 blanks
FIG. 2 shows the relationship between the sheet thickness and the sound volume (phone) of the sheet-shaped test sample 2 of each resin composition in the case of a phone. As is clear from FIG. 2, the sheet of the resin composition of the present invention was found to have excellent sound insulation properties. Furthermore, since the sheet properties, sound insulation properties, etc. were good, using the composition pellets of Examples 1 to 3, T-
A 65mmφ extruder equipped with a die, a width of 650mm,
T-die part resin temperature 210℃, screw rotation speed
Extruded under the condition of 100 rpm, areal density 2.0Kg/m ²
Then, it was laminated onto the original carpet to obtain a sound-insulating carpet. Table 2 shows the results of the backing suitability evaluation. The motor load had the composition of Example 2,
The increase/decrease is shown in % based on the load of LDPE/BaSO ₄ (50/50% by weight). The suture removal strength refers to the force (Kg) required to pull out one carpet pile, and for practical purposes, 1.3Kg or more is required. The odor can be removed by washing the carpet with the same composition in a glass container.
After aging at 60°C for 8 hours, a sensory test was conducted, and those with no odor were rated "◎", those with very little odor were rated "○", and those with a very strong odor were rated "x". The rank of satisfactory odor is "◎" or "○". Comparative Examples 1 to 2 The same evaluation of sheet physical properties as in Example 2 was carried out by changing the proportion of BaSO ₄ to 20 and 90 parts by weight. The results are shown in Table 1, but satisfactory physical properties could not be obtained, such as the small value of "fracture elongation" which affects the occurrence of cracks in the backing layer during press molding and handling, and poor sheet bending tests. , it turned out to be practically impossible. Comparative Examples 3 to 8 The resin/filler mixing ratio of Example 2 remained the same, but other fillers, CaCO ₃ , [Shiraishi Calcium Co., Ltd., Whiten SSB], talc [Nippon Talc Co., Ltd.], clay [Tsuchiya Kaolin Kogyo Co., Ltd., NH kaolin clay], zinc oxide [manufactured by Hakusui Chemical Industry Co., Ltd., zinc oxide No. 1], titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., Taipei 7R-]
820, A-100], iron oxide [Toda Kogyo, Todaclar
KRR] was used to evaluate the sheet properties in the same manner as above. The results are shown in Table 1, Comparative Example 1,
Similar to 2, a satisfactory composition could not be obtained and it was found to be impractical. Example 4 The LDPE of Example 2 was mixed with EVA [VAc = 3% by weight,
MI = 10, Asahi Dow prototype], and the same sheet property evaluation was performed. As shown in Table 3, the sheet properties were good. Therefore, Example 1 below
A 65φ extruder was operated under the same conditions as in 3-3, and the product was extruded through a T-die, and was buckled onto a carpet material to obtain a sound-insulating carpet. The bucking suitability evaluation results at that time are also summarized in Table 2.

【table】

【table】

[Table] Comparative Example 9 The proportion of BaSO ₄ in Example 4 was changed to 20 parts by weight,
The same sheet properties were evaluated below. The results are shown in Table 3, but like Comparative Example 1, the physical properties were not satisfactory. Comparative Example 10 The same evaluation of the sheet properties was carried out by replacing BaSO ₄ in Example 4 with CaCO ₃ . The results are shown in Table 3, and it was found that it was the same as Comparative Example 3 and could not be used practically. Comparative example 11 EVA of Example 4 was replaced with EVA with high VAc content.
[VAc = 20 wt%, MI = 20 Asahi Dow prototype], the sheet properties were evaluated in the same manner as below, and the results shown in Table 3 were obtained. Furthermore, in this example, the suitability for bucking in a 65φ extruder was evaluated in the same manner as in Example 1. The results are shown in Table 2, and it was found that although the sheet properties were good, the bucking suitability was significantly poor.

[Table] As described above, according to the present invention,
The combination of LDPE or EVA with a low VAc content and a filler whose main component is BaSO ₄ creates a sound-insulating carpet backing resin composition suitable for automobiles with good sheet properties and backing suitability, and low odor. By backing the composition onto carpet material, it is possible to produce sound-insulating carpet that is inexpensive, has good productivity, has excellent livability, and is suitable for automobiles. Summer.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus for evaluating the sound insulation properties of a sheet of the resin composition of the present invention, and FIG. 2 is a graph showing the results of evaluation using the apparatus. 1...Bell, 2...Test sample, 3...Sound level meter,
4... Lead plate, 5... Plywood board, 6... Box body, 7... Opening,
8... Presser frame.

Claims (1)

[Claims] 1 Low-density polyethylene or ethylene-vinyl acetate copolymer containing less than 5% by weight of vinyl acetate
A resin composition for sound insulating carpet backing consisting essentially of 60 to about 30 parts by weight of a filler based on barium sulfate and about 40 to about 70 parts by weight of a filler based on barium sulfate.