Abstract:
A laminated wooden container is made by sandwiching a bonding layer in between two wooden sheet members to form a laminated sheet material and then heat compressing and cutting the laminated sheet material under a predetermined temperature within 150° C. to 180° C. The bonding layer includes a base sheet material obtained from natural fibers, and a glue covered on two opposite surfaces of the base sheet material.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to the fabrication of food containers and more particularly, to a container fabrication method, which is practical for making laminated wooden food containers.  
         [0003]     2. Description of the Related Art  
         [0004]     Conventional disposable food containers include following five different type: Foamed Plastic Products, Degradable Plastic Products, and Paper Products. These products have drawbacks as outlined hereinafter: 
        1. Foamed Plastic Products: These products are commonly molded from foam EPS (polystyrene) that has a low hardness and low heat resisting power and, is not decomposable for more than one hundred year, and will release toxic substances when above 85° C. or burned. Therefore, these products are harmful to the environment and the immunological system of human beings.     2. Degradable plastic food containers: Plastic material is mixed with a photosensitive agent and a starch and processed into degradable material grains, and the degradable material grains are then molded into the desired degradable food containers. These products are water and oil proof, non-toxic, however its hardness is low. still has drawbacks as followed:     3. Paper food containers: These products are not protective against water and oil and have a low hardness. Therefore, these products can only be used to hold cold, dry food. Further, due to high reproduction cost, these products are not suitable for recycling and reproducing.        
 
         [0008]     In order to eliminate the aforesaid drawbacks, laminated wooden containers are developed. These products may be made by using a bonding glue to bond two wooden or bamboo sheet members together through a hot compression molding process, or bonding a wooden sheet member to a fiber layer and then molding the laminated structure into the desired product through a hot compression molding process. These laminated wooden containers meet environment awareness requirements, and have non-toxic, decomposable, hard and heat resisting characteristics. However, these two methods still have drawbacks as follows:  
         [0009]     The former method which uses a bonding glue to bond two wooden or bamboo sheet members together through a hot compression molding process cannot eliminate the permeation of the bonding glue into the tissues of the wooden or bamboo sheet members. Therefore, the finished products will crack easily. After hot compression molding, a post-processing is required to polish the coarsen surface and edge.  
         [0010]     A finished product made according to the later method which bonds a wooden sheet member to a fiber layer and then mold the laminated structure into the desired product through a hot compression molding will not crack easily due to the support of the fiber layer. However, a container made according to this method is not suitable for holding hot water or food because the fiber layer will decompose at high temperature. It may contaminate the contained food when the container starts to decompose. Further, a product made according to this method has a coarsen edge, which must be polished through a secondary processing process.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a laminated wooden container, which is nontoxic, not harmful, strong, heat resisting, microwavable, freezable, decomposable, sturdy and rigid structure, and clean to the environment.  
         [0012]     It is another object of the present invention to provide laminated wooden container fabrication method, which saves the manufacturing cost.  
         [0013]     The method of making a laminated wooden container comprises the steps of: (a) preparing two wooden sheet members and a bonding layer; (b) laminating the two wooden sheet members and the bonding layer together to have the bonding layer be sandwiched between the wooden sheet members to form a laminated sheet material; (c) preparing a hot compression molding mold; and (d) heat compressing said laminated sheet material by using the hot compression molding mold to form a container. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a schematic drawing showing the processing of laminating the two wooden sheet members and the bonding layer together according to the present invention.  
         [0015]      FIG. 2  is a schematic sectional view showing the use of a hot compression molding mold according to the present invention.  
         [0016]      FIG. 3  corresponds to  FIG. 2 , showing the second die closed on the first die according to the present invention.  
         [0017]      FIG. 4  is an elevated view of a laminated wooden container made according to the present invention.  
         [0018]      FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 4 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     Referring to  FIGS. 1-3 , the method of making a laminated wooden container in accordance with the present invention comprises:  
         [0020]     Step I: preparing two wooden sheet members  11 ,  12  and one bonding layer  13 , where the wooden sheet members  11 ,  12  are respectively obtained from  Albizia falcataria , each of the wooden sheet members  11 ,  12  having a thickness about 0.5 mm; the bonding layer  13  is obtained by covering the top and bottom surfaces of a base sheet material of recyclable natural long fibers with an eatable or biological glue by means of a coating or dipping technique;  
         [0021]     Step II: using rollers  2  to carry the wooden sheet members  11 ,  12  and the bonding layer  13  forwards and to have the wooden sheet members  11 ,  12  and the bonding layer  13  be laminated with the bonding layer  13  sandwiched between the wooden sheet members  11 ,  12 , as shown in  FIG. 1 , and then cutting the laminated structure into a blank sheet material  1  having a predetermined length and width, as shown in  FIG. 2 ;  
         [0022]     Step III: preparing a hot compression molding mold  3 , which comprises a first die  31 , which has a top wall  311 , a cavity  312  formed in the top wall  311 , and a groove  313  formed in the top wall  311  and spaced around the cavity  312 , and a second die  32 , which has a bottom wall  321 , a press block  322  downwardly protruding from the bottom wall  321  corresponding to the cavity  312  of first die  31 , and a cutting edge  323  downwardly protruding from the bottom wall  321  and spaced around the press block  322  corresponding to the groove  313  of the first die  31  (see  FIG. 2 );  
         [0023]     Step IV: placing the blank sheet material  1  on the first die  31  below the second die  2 , and then closing the second die  32  on the first die  31  and employing a pressure to the second die  32  against the blank sheet material  1  and the first die  31  at a temperature about 150-180° C., so as to process the blank sheet material  1  into the desired finished container  1 ′ as shown in  FIGS. 4 and 5 . The hot compression molding process of Step IV includes three continuously proceeded stages. During the first stage, a pressure about 25-55 kg/cm 2  is applied to the second die  32  against the blank sheet material  1  and the first die  31 , thereby causing the bonding layer  13  to be melted to bond the wooden sheet members  11 ,  12  together. During the second stage, a pressure about 35-65 kg/cm 2  is applied to the second die  32  against the blank sheet material  1  and the first die  31 , thereby causing the wooden sheet members  11 ,  12  to be ironed into a respective smooth surface. During the third stage, a pressure about 35-75 kg/cm 2  is applied to the second die  32  against the blank sheet material  1  and the first die  31  to force the cutting edge  323  completely into the groove  313  of the first die  31  to cut off the border area of the shape-formed blank sheet material  1 , and the desired finished container  1 ′ is thus obtained, as shown in  FIGS. 4 and 5 .  
         [0024]     The finished container  1 ′ thus obtained is sterilized by a UV (ultraviolet) sterilizer. When a number of finished containers  1 ′ are obtained and sterilized, they are arranged into stacks and packed by a vacuum packing machine for vending.  
         [0025]     According to the above description, the fabrication method of the present invention and/or the laminated wooden container made therefore have the following advantages: nontoxic, not harmful, strong, heat resisting, decomposable, sturdy and rigid structure, and clean to the environment. 
        1. The laminated wooden container made according to the present invention meets requirements for environmental protection. It has no residue and, is nontoxic, not harmful, strong, heat resisting, microwavable, freezable, decomposable, and clean to the environment. Further, waste laminated wooden containers can be burned to make charcoal, crushed for making furniture, or reclaimed for making paper. The reclamation cost of waste laminated wooden containers is low.     2. Because the invention uses the bonding layer  13  to bond the two wooden sheet members  11 ,  12  together, during heat sealing, only a small amount of the bonding glue will permeate into the tissues of the wooden sheet members  11 ,  12 . Further, due to the effect of the bonding layer  13 , the blank sheet material  1  is tough, and the finished laminated wooden container  1 ′ does not break easily during its use.     3. Except the eatable bonding layer  13 , the invention does not use any water repellent, smoothening agent, or any other chemical substances. The bonding layer  13  makes the container  1 ′ water-resistant. Further, because the bonding layer  13  is sandwiched between the wooden sheet members  11 ,  12 , it is isolated from contacting the food held in the container  1 ′. Therefore, the container  1 ′ is safe in use, and suitable for holding food.     4. Through one single hot compression molding process, the wooden sheet members  11 ,  12  and the bonding layer  13  are bonded together and shape-formed to have a smooth cutting edge. Because no further secondary processing process is needed, the manufacturing time is greatly shortened, and the manufacturing cost is greatly lowered.        
 
         [0030]     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. For example, three wooden sheet members and two bonding layers may be used to make a relatively stronger container through one single hot compression molding process. Accordingly, the invention is not to be limited except as by the appended claims.