JPH0357148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a foamed backing carpet using a powder polyethylene composition for crosslinking and foaming containing a polyethylene resin as a main component. (Prior Art and its Problems) Conventionally, carpets for automobile interiors have mainly been made by laminating a thin layer of low-density polyethylene onto a carpet base fabric. The laminated carpet is usually heated to a temperature at which the laminate softens and then formed by means such as a press to fit the irregularities of the automobile floor. Furthermore, a felt or foam sheet is laminated on the lower layer of the laminated carpet to provide cushioning and sound absorbing properties. Lamination of felt or foam sheets is usually carried out using an adhesive after molding. However, although the carpet laminate for automobile interiors obtained in this way can be molded to fit large unevenness on the floor surface of the automobile, it is difficult to fit small unevenness on the floor surface of the automobile. Even if it appears to fit over the unevenness of the surface, over time the fitting surface will become uneven, causing problems such as spoiling the aesthetic appearance. In particular, sagging on the edge surfaces at corners is the most likely to occur and be noticeable. On the other hand, it is difficult to fit small irregularities during normal manufacturing, and they are often not molded, and even if they are molded, it is insufficient, and the surface is often rather flat at the beginning of manufacturing. However, as the carpet surface is repeatedly pressed against the floor surface over time, small irregularities on the floor surface appear on the carpet surface, resulting in an aesthetic problem. Furthermore, in order to provide cushioning and sound absorption properties, a separate process of laminating felt or foam sheets onto the laminated carpet is required, making the process complicated and significantly increasing manufacturing costs. Improvements are desired. It is rare. Felt, which is mainly used as a cushioning material for automobile interior carpets, is made primarily of accumulated and solidified fiber waste, and has drawbacks such as being prone to dust, having a unique odor, and being poor in water resistance. and
The emergence of alternative materials is strongly desired. Furthermore, the processes that were previously required for automobile interior structures are
The process involves polyethylene lamination on the carpet base fabric, molding process, adhesive application (although this is not necessarily an essential process), and foam sheet or felt lamination process, which requires many processes and is very complicated. It was hot. In other words, as a carpet structure for the interior of an automobile, areas that should be uneven will not lose their shape or sag over a long period of time, and unnecessary unevenness of the floor circle will not appear on the carpet surface, providing more comfortable cushioning and sound absorption properties. Carpet structures have not conventionally existed, and of course, there has also been no known method for manufacturing them with low cost and simple steps. In view of the above-mentioned drawbacks of the conventional products, the present inventors conducted intensive research to solve these problems, and as a result, they came up with the present invention. (Means and Effects for Solving Problems) The present invention provides low-density polyethylene (hereinafter also referred to as PE) having a melt index of 4 or more and 60 or less.
Ethylene vinyl acetate copolymer (hereinafter referred to as EVA), ethylene and acrylic acid ester copolymer (hereinafter referred to as EEA), ethylene and unsaturated carboxylic acid copolymer (hereinafter referred to as EAA, EMA),
or 100 parts of a base resin made of one or more polymers selected from ionomer resins, 2 parts to 15 parts of a blowing agent with a decomposition temperature in the range of 90°C to 190°C, and a half-life temperature of 1 hour. is 100℃
0.2 parts or more of crosslinking agent in the range of 160°C or more and 1.5 parts or more
200 g/m 2 or more 2000 g/m ² of a powder composition consisting of 0.02 parts or more and 7.5 parts or less of an auxiliary agent selected from metal soap or metal oxide ^.
This is a method for producing a closed-cell foam bagging carpet, which is characterized by dispersing in the following range, heating, and foaming after starting crosslinking. By using the powder composition of the present invention, the steps conventionally required to complete a carpet structure for an automobile interior can be greatly shortened. In other words, as already mentioned, the backing process (powder composition It can be simplified into two steps: a spraying step, a crosslinking and foaming step by heating, and a molding step. In the present invention, the carpet structure refers to a carpet molded product obtained through a molding process. In particular, the important point in the present invention is that by using a powder composition for crosslinking and foaming of polyethylene or its copolymer, the lamination process of polyethylene laminate (backing) and cushioning material (foam sheet, felt, etc.), which was previously required, can be eliminated. The adhesive application process (although not necessarily required) is simplified to a simple continuous process of powder dispersion, heating, crosslinking and foaming, and the backing is performed.
Furthermore, in the present invention, since the laminate material and the cushion material are made of the same backing material and are cross-linked and foamed, rigidity and thickness are imparted to the carpet body. At the same time, even if the material is subjected to repeated compression over time, no sagging will occur in the uneven portions, especially at the edges. An example of the present invention is shown in FIG. 1, and an example of a conventional felt laminate product is shown in FIG. In Figure 1, 1 is carpet, 2 is PE foam, and
In the figure, 1 is carpet, 2 is PE laminate, 3 is adhesive, and 4 is felt. Furthermore, since the backing of the present invention is a foamed material, the backing material penetrates into small irregularities on the automobile floor surface during molding, as shown in FIG. 1 is carpet, 2 is
PE foam, 3 indicates the car floor surface. As a result, there is no appearance problem caused by the appearance of small irregularities on the carpet surface (as shown in FIG. 4) after the passage of time, which is seen in conventional polyethylene laminate carpets. In FIG. 4, 1 is a carpet, 2 is a felt, and 3 is an automobile floor surface. The base resin used in the present invention is preferably polyethylene or ethylene copolymer. Various known polymeric materials can be used as foam materials for cushions, but they are industrially inexpensive and stably available, have cushioning properties suitable for carpet backing, and are easy to mold. EVA, EEA,
A base resin which is a polyethylene resin consisting of one or more polymers of EAA, EMA or ionomer resins is suitable. In the present invention, a base resin made of one kind of polyethylene resin or a base resin made of two or more kinds of polyethylene resins can be suitably used. In the case of two or more types, examples include a blend system of low density polyethylene and EVA, EEA, EMA, or ionomer resin. This is suitable for controlling adhesion to carpet, cushioning properties, etc. as carpet backing. For example, when low-density polyethylene alone is too rigid, a blend system with EVA is used to provide appropriate cushioning properties, and when strong adhesion to carpet is required, a blend system with EEA or EAA is preferable. It can be used. In addition, the melt index (hereinafter also referred to as MI) of the polyethylene resin is 4 (g/10 mm) or more 60
(g/10mm) or less (measured according to ASTM D1238)
If the melt index is less than 4, not only a sufficient expansion ratio cannot be obtained but also good adhesion to the carpet base material cannot be obtained. Furthermore, if the melt index exceeds 60, the foaming and cells will be non-uniform and the foam will be open-celled, making it impossible to obtain effective cushioning properties. The more preferable range is 5 to 50.
(g/10mm). As a blowing agent, the decomposition temperature is
90℃ or higher and 190℃ or lower should be selected, such as azodicarbonamide (ADCA),
N,N′ dinitropentamethylenetetramine (DPT), benzenesulfonyl hydrazide (O.
B.SH) Para-toluenesulfonyl hydrazide (TSH) and the like are preferred, and products containing these foaming aids may also be used. The decomposition temperature is 90℃.
If it is less than this, there will be a tendency for foaming to occur when the composition of the present invention is kneaded in an extruder, which is undesirable, and also it will not be possible to obtain sufficiently uniform foamed cells even during bagging. In addition, if the material has a decomposition temperature exceeding 190°C, it not only takes a long time for crosslinking and foaming in the backing process, but also results in only low foaming in the area that contacts the base fabric of the carpet, resulting in poor cushioning properties. You can only get things. A more preferred decomposition temperature is 115-170°C.
Note that it is necessary to add the blowing agent in an amount of 2 parts or more and 15 parts or less. If the amount added is less than 2 parts, a foaming ratio sufficient to provide sufficient cushioning properties cannot be obtained, and if it exceeds 15 parts, the foamed cells will become coarse and at the same time there will be problems in terms of cost. A more preferable addition amount is 4 to 13 parts. The crosslinking agent acts to increase the viscosity of the resin in order to provide membrane strength to the foamed cells during foaming, and in the present invention, it is required to have a one-hour half-life of 100°C or more and 160°C or less. If this temperature is less than 100°C, the composition will undergo crosslinking too quickly upon heating, and not only will it not be possible to obtain a good foamed state, but also the adhesion to the base fabric will not be good. Furthermore, during the production of this composition, early crosslinking also occurs during heating and mixing, which is undesirable. On the other hand, if the temperature exceeds 160°C, foaming occurs before crosslinking, resulting in insufficient membrane strength of the foamed cells and open cells, making it impossible to obtain uniform foamed cells. More preferred crosslinking agents are those with a 1 hour half-life of 105 to 150°C. Foaming aids include metal soaps or metal oxides, such as calcium stearate,
Preferred are zinc stearate, barium stearate, aluminum stearate, lead stearate, zinc oxide, titanium oxide, and the like. In particular, in the composition of the present invention, one or a mixture of two or more of calcium stearate, zinc stearate, zinc oxide, and lead stearate is optimal from the viewpoint of uniformity of foam cells. The amount added is in the range of 0.02 parts or more and 7.5 parts or less, preferably 0.05 to 2.5 parts. If the amount added is less than 0.02 parts, uniform foam cells cannot be obtained, and if it exceeds 2.5 parts, problems will arise in the strength of the foam backing itself and its adhesion to the carpet base material. The present invention is characterized in that the composition is a powder. Performance such as adhesion to the carpet base material, good cushioning properties, and resistance to deformation after molding can be achieved only by dispersing the powder composition of the present invention onto a carpet base material and passing through a crosslinking and foaming process by heating. Ru. These performances cannot be imparted simply by extrusion and lamination of the composition of the present invention. The powder composition of the present invention can be produced by simply dry blending the polyethylene resin powder with a blowing agent, crosslinking agent, auxiliary agent, etc., but these components may be kneaded and pelletized in an extruder to prevent crosslinking and foaming. It is also preferable to use a method in which the powder composition is then mechanically pulverized to form a powder composition. The mechanically pulverized powder has a bulk density of 0.20 or more, preferably 0.25 or more. If it is less than 0.20, it becomes difficult to uniformly spread the powder onto the carpet base material, and the adhesion to the base fabric tends to be poor. The backing of the carpet in the present invention is obtained as follows. That is, the powder composition of the present invention is spread on a carpet base fabric so that it has a uniform thickness. The amount to be sprayed is 200g/ ^m2 or more2000
About g/m ² is preferable. If the amount of spraying is less than 200g/ ^m2 , effective cushioning properties cannot be obtained;
If it exceeds m ² , foaming becomes non-uniform and at the same time, there is almost no foaming in the areas that come into contact with the carpet base fabric, resulting in a tendency to lose cushioning properties. The spraying amount is more preferably in the range of 300 to 1500 g/m ² . The carpet on which the powder has been sprinkled is then heated, such as by passing it through a hot air furnace or an infrared heating furnace, to melt, crosslink, and foam the powder composition of the present invention. It is also possible to divide the heating process into two steps, melting in the first heating process, and crosslinking and foaming in the second heating process. The heating conditions vary depending on the material of the carpet, the composition of the powder, the expansion ratio, the amount of powder sprayed, etc., but the heating treatment is usually carried out at an ambient temperature range of 110°C to 250°C for several tens of seconds to several tens of minutes. The foaming ratio of bucking obtained by the present invention is 2 to 20
It's twice as much. The carpet backing thus obtained is a fine and uniform crosslinked foam backing that firmly adheres to the carpet base fabric and has excellent cushioning properties. The buckled carpet thus obtained (as shown in FIG. 1) is reheated above the softening temperature of the buckling and press-formed in a mold as shown in FIG. In Fig. 5, 3 is the upper mold;
5 is the lower mold, 5 is the carpet, and 6 is the PE foam. At this time, the backing not only tightly fits into the large protrusion 1 of the press mold, but also enters into the small recess 2 because the backing is made of foam.
The carpet structure obtained in this way is then fitted onto the uneven floor of an automobile, etc., and the parts where it is molded as a carpet interior material do not lose their shape over time, and the flat parts do not lose their shape over time. It remains flat forever and small irregularities on the floor will not appear on the surface. (Examples) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. The foaming ratio, cushioning properties, shape retention properties, and adhesion properties of the backed carpets obtained in each example were measured using the following methods. (1) Foaming ratio; foaming ratio is B, unit area (1cm ² )
It was determined as B=(T/W)·ρ, where W is the spray amount per unit, resin density ρ, and backing thickness Tcm. (2) Cushioning property: People actually walk on the carpet and it is judged as having elasticity. (3) Shape retention: A person walked on the carpet shown in Figure 6 and visually judged the sagging in the area shown in Figure 6-1 and the depression in the area shown in Figure 6-2. In the same figure, 1 is a carpet, 2 is a PE foam, and 3 is a steel plate. Those with no sagging or depressions were evaluated as ○, and those with dents were evaluated as ×. (4) Adhesion: Judgment was made by manually peeling off the carpet and backing. Example 1 Low density polyethylene (M6520, manufactured by Asahi Kasei,
MI; 20,) 100 parts (All parts hereinafter refer to parts by weight.) 7 parts of ADCA (Vinihole AC #3, manufactured by Eiwa Kasei) as a blowing agent, α,α′-Bis ( t-betyl peroxy-m-
1 part of isoPropyl) benzene (Parkadox-14, manufactured by Kayaku Nouri, 1 hour half-life: 135°C) and 1 part of zinc stearate as an auxiliary agent were kneaded using an extruder and pelletized. Next, a powder with a 60 mesh pass was obtained using a Pohlmann mill mill (manufactured by Pohlmann, West Germany). The bulk density of the powder was 0.30. The obtained powder was then uniformly spread in an amount of 700 g/m ² on the base fabric side of a polyester-based carpet. Then, the mixture was placed in a hot air oven at 190°C for 10 minutes to obtain a crosslinked foam backing carpet. Table 1 shows the expansion ratio and adhesiveness of this product. The bagged carpet was then reheated to 150 DEG C. in a hot air oven and molded in the mold shown in FIG. Further, the molded carpet structure was fitted onto the steel plate shown in FIG. 6, and its cushioning properties and shape retention properties were evaluated. The results are shown in Table 1. Examples 2, 3, 4 The same procedure as in Example 1 was carried out except that M6545 and M2270 (both manufactured by Asahi Kasei) were used as low-density polyethylene, zinc oxide and calcium stearate were used as auxiliaries, and the formulations shown in Table 1 were used. It was evaluated. Examples 5, 6, 7, 8 EM5822 (EVA, manufactured by Asahi Kasei), DPDJ8026 (EEA, manufactured by Nippon Unicar), Surlyn 1652 (ionomer resin, manufactured by Mitsui Polychemical), and A210M (EAA, manufactured by Mitsubishi Kasei) were used as base resins. , ADCA/DPT mixture (Vinihole AK) as a blowing agent
#2, manufactured by Eiwa Kasei) 1,1-Bis as a crosslinking agent
(t-butyl peroxy)3,3,5-trimethyl
The formulations shown in Table 1 were used except that cyclohexane (Perhexa 3M, manufactured by Nippon Oil & Fats Corporation) was used, and the evaluation was carried out in the same manner as in Example 1. Examples 9 and 10 OBSH (Neocellvon, manufactured by Eiwa Kasei) as a blowing agent, TSH (Uniphor, manufactured by Eiwa Kasei) as a crosslinking agent, t-butyl Peroxyacetate (Perbutyl A,
(NOF), t-butyl Peroxy
Evaluation was conducted in the same manner as in Example 5 except that isopropyl carbonate (Perbutyl, manufactured by NOF Corporation) was used and the formulation in Table 1 was followed.Examples 11 and 12 M6520/
50 parts/50 parts blend of EM5822 and M6520/
Evaluation was carried out in the same manner as in Example 1 except that a blend of 50 parts > 50 parts of DPDJ8026 was used. Table 1 shows the results.
It was shown to. Comparative Example 1 Evaluation was carried out in the same manner as in Example 1 except that no auxiliary agent was used. Comparative Example 2 Evaluation was carried out in the same manner as in Example 1, except that no crosslinking agent or auxiliary agent was used. Comparative Example 3 The formulation was evaluated by laminating foams by T-die extrusion without powder scattering according to Table 1. Comparative Example 4 Example 1 except that the amount of powder sprayed was 180 g/m ²
It was evaluated in the same way. Comparative Example 5 The cushioning properties and shape retention properties of a structure made of carpet/polyethylene laminate/felt were evaluated in the same manner as in Example 1. 【table】

[Brief explanation of drawings]

1, 3, 5, and 6 are explanatory diagrams of an example of the present invention, and FIGS. 2 and 4 are explanatory diagrams of the prior art.

Claims (1)

[Claims] 1 Melt index is 4 or more and 60 or less,
One or more polymers selected from low-density polyethylene, ethylene-vinyl acetate copolymers, copolymers of ethylene and acrylic esters, copolymers of ethylene and unsaturated carboxylic acids, and ionomer resins. 100 parts of base resin, blowing agent 2 whose decomposition temperature is in the range of 90°C or more and 190°C or less
0.2 parts or more and 1.5 parts or less of a crosslinking agent whose half-life temperature per hour is 100°C or more and 160°C or less, and 0.02 parts or more and 7.5 parts or less of an auxiliary agent selected from metal soaps or metal oxides. Production of a closed-cell foam backing carpet characterized in that a powder composition consisting of the following is dispersed on a carpet base fabric in a range of 200 g/m ² or more and 2000 g/m ² or less, heated, and foamed after crosslinking is initiated. Method.